Mold in leather production

Mold growth in leather
Fungal deterioration is apparent from the growth on the leather of molds. Moulds are part of the group known as fungi - a group of unique organisms that sit uneasily between microbiology and botany. They are neither filamentous bacterium nor are they similar to green plants.
There are many strains of mold that are capable of growing on leather, but often the presence of one strain suppresses the appearance of others. Aspergillus niger, for example, usually results in the inhibition of other strains, although the others are quite capable of widespread growth in the absence of A. niger.
Like all living organisms they need certain basics to grow and multiply: a source of moisture and a source of nutrient. In wet-blue leather the source of moisture is clear.
In finished leather the moisture content is very much lower and the growth of mold is less, but when transporting leather between different climatic zones, or if storing leather in an inappropriate manner, moisture build up in certain areas, such as just inside any packaging, can readily lead to the growth of mold. Many of the process chemicals used in the manufacture of leather act as nutrients for mould growth, examples include ammonium salts, phosphates, surfactants, fatliquoring agents and other organic agents.
The appearance of the mold growth is related to the type of mold present. In the minds of many people mould is usually associated with green/grey growths. Tanners, however, may also be familiar with the red spots or red discolouration caused by Paecilomyces ehrlichii, P. aculeatum, P. purpurogenum and P. roseopurpureum.
In poorly controlled drying operations, where the humidity remains high or air circulation is poor, other types of growths may also be found, giving rise to other coloured appearance such as green, yellow-brown, dark-brown and grey. Strains associated with damage arising from poor drying control, include A. ochraceus, A. wentii, P. rugulosum, P. funiculosum, P. variotii and V. glaucum.
Tropical chamber mold resistance test
Test method
The leather samples were evaluated for their resistance to mold growth by exposure in a tropical chamber for 28 days.
The tropical chamber consists of an insulted cabinet that is maintained at a temperature of 27 to 30 degree Celsius and a humidity level of 95 to 100 %, and has been inoculated with the spores of fungal species that commonly attack leather, including Aspergillus and Penicillium species. This tropical chamber environment is highly conductive to fungal growth and this method is intended for the accelerated evaluation of mold resistance.
Several replicate test pieces measuring 7cm by 10 cm are cut from each leather sample and exposed in the tropical chamber. The leather pieces are inspected weekly and rated for fungal growth. The rating system is based on the percentage of the leather surface covered with mold. The scale is from 0 to 100: 0 mean 0% of the surface is covered with mold and 100 mean 100% of the surface is covered.
Interpretation of the mold resistance ratings:
 Long-term mold resistance : a rating of 0 to 20 in week 4
 Medium-term mold resistance: a rating of 0 to 20 in 3 week
 Short-term mold resistance: a rating of 0 to 20 in 2 week
 Limited mold resistance: a rating of 0 to 20 in 3 week
 No mold resistance: a rating greater than in 1 week

Shafi Reso chem.
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The annual leather article show fashion forecast spring summer 2011 was held at National Institute of Leather Technology on Thursday 25, February by Shafi Reso Chem. a leading leather chemical producer in Pakistan. The new season of spring leather fashion collection and the range of new or modified product were introduced. Shafi Reso is helping hand of Pakistan leather industry as local supplier of leather chemical with low cost. Products range from biocide, degreasing agents batting agents and finishing pigment.


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SHAFI RESO-CHEM is a part of the Shafi Group, a leading Pakistani producer for the leather and leather article industry. Since its inception in 1994, the company has enjoyed a successful and continuous growth in both domestic and international (South & Middle Eastern) markets. In today's competitive arena, where customization and professionalism are at a premium, we feel we offer our customers an unparalleled blend of quality, consistency, responsiveness, and innovation.

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leather point: Vegetable tanning

leather point: Vegetable tanning

leather point: Vegetable tanning

leather point: Vegetable tanning

Vegetable tanning

Vegetable tanning
With the industrial application of chrome tannage rapidly advancing since the end of the last century vegetable tannage has been ousted from its predominant position into second place. Moreover synthetic tanning agents were invented by the condensation of phenols with formaldehyde and further developed with great number of aromatics. In the past decades syntans having very particular properties have been produced. In many cases they improved the vegetable tanning agents in terms of tanning technique and were sometime even superior. This led to a great number of combinations of vegetable tanning agents with syntans, which modified the tanning methods and also the properties of the leather.
Vegetable tanning materials
Vegetable tanning agents most commonly used worldwide:
Barks: mimosa, mangrove, acacia negra, eucalyptus
Fruits: myrobracho, chestnut, oak
Leaves: sumac, gambir
Tanning properties of the most important tanning agents
Hydrolysable tanning agents (pyrogallol=acid former)

---------Color--------- fullness--------------tannage---------------other

Oak------yellow, brown, dark cut--- full--------very firm -----------acid forming

Chestnut--pale,yellow olive tinge-----full-------firm-------------bloom forming

Myrobalan----pale-colored---------medium------little strength-----strongly sludging

Sumac----almost white tanning------ medium -----soft supple------good light fastness

Valonea grey-brown pale-colored -----medium full------tough firm------low content of insoluble matter

Condensable tanning materials (catechol=phlobaphene former

------------Color---------Fullness----------Tanning------------- Other
Pine ------- pale –brown --------- medium fullness-----------firm hard------------become darker on exposure to light

Mangroves-intensive red brown-----medium------------loose, spongy-----------strongly sludging

Mimosa--pale, slightly reddish tinge----full---------quick firm supple-------becomes darker on exposure to light
Untreated

Mimosa-sulphited-bleaching dull beige—medium full---medium-full----medium firm fine grain—bleaching readily soluble

Quebracho-ordinary ---very intensive reddish tinge----full---slightly softer than mimosa-----strongly sludging
Quebracho sulphited- intensive reddish tinge---medium full------ slightly softer than mimosa—cold soluble



Light and heat fastness modified mimosa for vegetable tanning


Tanac specialise in providing the leather industry with Mimosa based products farmed from their FSC certified plantations of Acacia in Brazil. By modifying the extract they have devised new high-performance extracts for upholstery and upper leathers

Mimosa or Acacia are native Australian species introduced to southern Brazil in the 1920s and rapidly becoming a sustainable economic product. At present, there are 150,000 hectares of Acacia forests in Brazil of which 30,000 hectares belong to Tanac. There are also more than 30,000 small farms, which supply Tanac with enough bark to produce 36,000 tons of vegetable products per year. These products are used in various areas such as the production of leather and adhesives as well as in water and effluent treatment.
The forests belonging to Tanac are certified by the FSC (Forest Stewardship Council), which guarantees a sustainable raw material complying with
the most stringent environmental regulations. Conventional Mimosa extracts are versatile and provide a variety of characteristics such as naturally light colouration, low acid and salt content, low viscosity and natural pH ranging from 4.0 to 5.0. They also provide stability to hydrolysis and electrolytes, good resistance to iron salts, fast penetration and stability to damage caused by microorganisms.
In spite of their wide application and versatility, the Mimosa extracts which are available on the market do not fully satisfy all the needs of upholstery leather makers, especially those of automotive leather. Thanks to its chemical structure, Acacia tannin is a natural antioxidant (figure 1), being often used to this end. This feature alters the colouration of the leather produced when exposed to light or heat.
Production of furniture, automotive, aviation and aquatic upholstery articles as well as footwear upper and leathergoods requires a high specification. The demand for these leather types is growing, particularly if they have good physical and environmental credentials. Characteristics such as light shades and heat and lightfastness are important. The products currently used to this end are not extracts but ground products obtained from irregular sources and contain impurities (some insoluble ones) that affect the quality of the final goods.

Modifying Mimosa
By means of chemical modification of Mimosa extracts, lightfastness may be increased so that significant leather colouration changes do not occur after upholstery articles have been produced. These alterations take place through chemical modification where specific radicals are added to the original molecule so that they provide the extract with the capacity to reduce oxidation when exposed to sunlight or other sources of light, resulting in a lower degree of colour alteration.
Organic chemical reactions are the best way to provide heat and light stability to raw materials by using efficient protective groups. These groupings prevent electronic resonance between the B aromatic link and its free hydroxyls thus stabilising the molecular structure and guaranteeing a lower degree of alteration of the extract colour and, consequently, that of the leather tanned with new modified Mimosa (such as Tanac’s Supertan LTA).
Using modified Mimosa with such characteristics makes it possible to produce tanned and retanned leather where a light colour as well as heat and lightfastness are possible.
These additional properties are added to other favourable characteristics of Mimosa extracts such as fast penetration, smooth open grain, good filling and excellent softness. Figure 2 shows a significant improvement in heat and lightfastness when using modified Mimosa compared with standard Mimosa extract. In figure 2 the samples were treated with heat, natural and UV light and the discolouration measured.
The colouration provided by modified Mimosa and Tara are quite similar.
Physical, chemical and mechanical tests carried out on automotive upholstery leather, comparing modified and standard products, showed a significant improvement in the results obtained from the article that used modified Mimosa compared to regular Mimosa extract. It may also be noted that both products reached
the parameters required in OEM upholstery leathermaking including a significant increase in the tensile strength in the sample, which used modified Mimosa as the retanning agent.

Footwear upper
Taking into consideration that the production of upper leather accounts for more than 50% of global leather consumption and that this market is evolving fast as far as quality of the final goods are concerned, Tanac have also developed modified Mimosa as a sustainable alternative for the market.
Table 1 highlights the results of the physical and mechanical tests carried out on footwear leather samples. It shows an improvement in the results obtained from leathers where modified Mimosa was applied compared to standard Mimosa extracts.
Vegetable tanning method
1. Old pit method
Tannage, lasting about 12-18 months, is performed according to the counter –current principle with thin tanning liquors in the color pit. Long duration required in this method now only used in isolated cases. The label “old pit method means” tanning with oak and pine bark which provides specially compact and firm sole leather having a low content of substances removable by washing. Prolonged tanning is a disadvantage.
2. Accelerated tannage with tan solutions of higher concentration
Final tanning is performed by further increasing the concentration using higher- percentage tanning agents and tan liquors of higher concentration, in the handler and lay-away respectively, and by additional mechanical agitation in the drum. Duration reduced 2-6 months. Compared to slow pit method bonding of tannin is slightly reduced and the content of substances removable by washing is considerably higher.
3. Quick tanning methods
They are all based on the principle of increased concentration, mechanical agitation, increased temperature and pH variation. The duration of tanning is reduced to 4-20 days, depending on the operational condition and type of leather.
4. Rapid tanning method
These are powder tanning substances without float. The best known methods are
1. RFP process of BAYER
2. Rapitan process of BASF
They reduced the duration of tanning to 2-3 days. The hides should be well prepared for these tanning methods and the vessels should be suitable in order to reduce possible error and avoid case-harding.
Vegetable tanning process
1. Complete soaking and liming
2. Complete removal of the subcutaneous tissue by through fleshing
3. Complete deliming of all sections of the skin. Dry deliming and the addition of sodium hydrogen sulfide as well as aromatic sulpho acids are good for thick pelts.
4. The formation of false backs is avoided by slashing the butts along the backbone line.
5. Pretanning with small particle synthetic pretanning agents of low astringency. Also preliminary treatment with glutaraldehyde, polyphosphates or pickles containing chrome salts or chromiferrous syntans.
6. Through washing after pretannage and good draining of the residual liquor.
7. Addition of the powder tanning agents for final tanning in 2-3 portions and addition of dispersing tanning agents in appropriate quantities. Temperature raises not exceeding 38 ⁰ C.
8. Addition of a slip additive or untreated oil to reduce friction.

tanning

Tanning is the process of making leather, which does not easily decompose, from the skins of animals, which do. Often this uses tannin, an acidic chemical compound. Coloring may occur during tanning. A tannery is the term for a place where these skins are processed. Tanning leather involves a process which permanently alters the protein structure of skin so that it cannot ever return to rawhide. Making rawhide does not require the use of tannin and is made simply by removing the flesh and fat and then the hair by way of soaking in an aqueous solution (often called liming when using lime and water or bucking when using wood ash (lye) and water), then scraping over a beam with a somewhat dull knife, and then leaving to dry, usually stretched on a frame so that it dries flat. The two aforementioned solutions for removing the hair also act to clean the fiber network of the skin and therefore allow penetration and action of the tanning agent.
The English word for tanning is from medieval Latin tannāre, deriv. of tannum (oak bark), related to Old High German tanna meaning oak or fir (related to modern Tannenbaum). This refers to use of the bark of oaks (the original source of tannin) in some kinds of hide preservation. [1]
In ancient history, tanning was considered a noxious or "odiferous trade" and relegated to the outskirts of town, amongst the poor. Indeed, tanning by ancient methods is so foul smelling that tanneries are still isolated from those towns today where the old methods are used. Ancient civilizations used leather for waterskins, bags, harnesses, boats, armor, quivers, scabbards, boots and sandals. Tanning was being carried out by the South Asian inhabitants of Mehrgarh between 7000–3300 BC.[2] Around 2500 BC, the Sumerians began using leather, affixed by copper studs, on chariot wheels.
Skins typically arrived at the tannery dried stiff and dirty with soil and gore. First, the ancient tanners would soak the skins in water to clean and soften them. Then they would pound and scour the skin to remove any remaining flesh and fat. Next, the tanner needed to remove the hair fibers from the skin. This was done by either soaking the skin in urine, painting it with an alkaline lime mixture, or simply letting the skin putrefy for several months then dipping it in a salt solution. After the hair fibers were loosened, the tanners scraped them off with a knife.
Once the hair was removed, the tanners would bate the material by pounding dung into the skin or soaking the skin in a solution of animal brains. Among the kinds of dung commonly used were that of dogs or pigeons. Sometimes the dung was mixed with water in a large vat, and the prepared skins were kneaded in the dung water until they became supple, but not too soft. The ancient tanner might use his bare feet to knead the skins in the dung water, and the kneading could last two or three hours.
It was this combination of urine, animal feces and decaying flesh that made ancient tanneries so odiferous.
Children employed as dung gatherers were a common sight in ancient cities. Also common were "piss-pots" located on street corners, where human urine could be collected for use in tanneries or by washerwomen. In some variations of the process, cedar oil, alum or tannin were applied to the skin as a tanning agent. As the skin was stretched, it would lose moisture and absorb the agent.
Leftover leather would be turned into glue. Tanners would place scraps of hides in a vat of water and let them deteriorate for months. The mixture would then be placed over a fire to boil off the water to produce hide glue.
Variations of these methods are still used by do-it-yourself outdoorsmen to tan hides. The use of brains and the idea that each animal (except buffalo) has just enough brains for the tanning process have led to the saying "Every animal has just enough brains to preserve its own hide, dead or alive".[citation needed]
[edit] Modern methods


Tanneries of Marrakech


Two men pressing the leather near the end of the tanning process in an American tannery. circa: 1976
The first stage is the preparation for tanning. The second stage is the actual tanning and other chemical treatment. The third stage, known as retanning, applies retanning agents and dyes to the material to provide the physical strength and properties desired depending on the end product. The fourth and final stage, known as finishing, is used to apply finishing material to the surface or finish the surface without the application of any chemicals if so desired.
Preparing hides begins by curing them with salt. Curing is employed to prevent putrifaction of the protein substance (collagen) from bacterial infection during the time lag that might occur from procuring the hide to when it is processed. Curing removes excess water from the hides and skins using a difference in osmotic pressure. The moisture content of hides and skins get greatly reduced. In wet-salting, the hides are heavily salted, then pressed into packs for about 30 days. In brine-curing the hides are agitated in a salt water bath for about 16 hours. Generally speaking, methods employed for curing make the chance of bacterial growth greatly unfavorable. Curing can also be done by preserving the hides and skins at a very low temperature.
In a process known as soaking, the hides are then soaked in clean water to remove the salt and increase the moisture so that the hide or skin can be further treated.
[edit] Liming process of hides and skins
After soaking, the soaked hides and skins are taken for the next operation where these are treated with milk of lime (a basic agent) with or without the addition of "sharpening agents" (disulfide reducing agents) like sodium sulfide, cyanides, amines etc. The objective of this operation are mainly to:
• Remove the hairs, nails and other keratinous matters
• Remove some of the interfibrillary soluble proteins like mucins
• Swell up and split up the fibers to the desired extent
• Remove the natural grease and fats to some extent
• Bring the collagen in the hide to a proper condition for satisfactory tannage
The weakening of hair is dependent on the breakdown of the disulfide link of the amino acid called cystine, which is the characteristic of the keratin class of protein which gives strength to hair and wools (keratin typically makes up 90% of the dry weight of hair). The hydrogen atoms supplied by the sharpening agent reduce the cystine molecular link to cysteine, and the covalent disulfide bond links are ruptured. This weakens the keratin. To some extent, the weakening produced by sharpening also contributes to "unhairing," as the hairs break down.
The isoelectric point of the collagen in the hide (this is a tissue strengthening protein unrelated to keratin) is also shifted to around 4.7 due to liming, which is an acidic type of tannage.
Unhairing agents used during liming are:
• Sodium sulfide
• Sodium hydroxide
• Sodium hydrosulfite
• Arsenic sulfide
• Calcium hydrosulfide
• Dimethyl amine
• Sodium sulphydrate
The majority of hair is then removed using a machine, with remaining hair being removed by hand using a dull knife, a process known as scudding. Depending on the end use of the leather, hides may be treated with enzymes to soften them in a process called "bating." But before bating, the pH of the collagen is brought down to a lower level so that enzymes may act on it. This process is known as "deliming."
Once bating is complete, the hides and skins are treated with a mixture of common (table) salt and sulphuric acid, in case a mineral tanning is to be done. This is done to bring down the pH of collagen to a very low level so as to facilitate the penetration of mineral tanning agent into the substance. This process is known as "pickling." The common salt (sodium chloride) penetrates the hide twice as fast as the acid and checks the ill effect of sudden drop of pH.
Tanning can be performed with either vegetable or mineral methods. Before tanning, the skins are unhaired, degreased, desalted and soaked in water over a period of 6 hours to 2 days. To prevent damage of the skin by bacterial growth during the soaking period, biocides, such as pentachlorophenol, are used.
Vegetable tanning uses tannin (this is the origin of the name of the process). The tannins (a class of polyphenol astringent chemical) occur naturally in the bark and leaves of many plants. Tannins bind to the collagen proteins in the hide and coat them causing them to become less water-soluble, and more resistant to bacterial attack. The process also causes the hide to become more flexible. The primary barks used in modern times are chestnut, oak, tanoak, hemlock, quebracho, mangrove, wattle (acacia; see catechu), and myrobalan. Hides are stretched on frames and immersed for several weeks in vats of increasing concentrations of tannin. Vegetable tanned hide is flexible and is used for luggage and furniture.
Mineral tanning
Chrome tanning:
Tanner`s golden rule
Colloid-chemical:
Hydrophilic –pretanning with small particles
Hydrophobic-final tanning with large particles
Or tannage
Start with low astringency and low propensity for bonding,
Finish with high astringency and high propensity for bonding
Or according to the countercurrent principle
Fresh tan / spent tan
The basicity of chrome tannage should be in a range of about 50-60% in order to achieve the best possible tang effect and sufficient resistance to boiling and also to attain a good bonding to skin fibers and a high degree of exhaustion of the tan liquor this is done by means of products with an alkaline reaction during or at the end of tanning process.

Usually uses chromium in the form of basic chromium sulfate. It is employed after picking. Once the desired level of penetration of chrome into the substance is achieved, the pH of the material is raised again to facilitate the process. This is known as "basification". In the raw state chrome tanned skins are blue and therefore referred to as "wet blue." Chrome tanning is faster than vegetable tanning (less than a day for this part of the process) and produces a stretchable leather which is excellent for use in handbags and garments.
High-extraction chrome tanning process
United States Patent 4919680
Crome tanning of pickled animal hides with a tanning agent comprising a reaction product of a basic chromium (III) sulfate and aliphatic C4 -C6 dicarboxylic acids or their salts is improved by preparing the reaction product in an aqueous solution from basic chromium (III) sulfate and 0.2 to 0.8 mol of the aliphatic dicarboxylic acids per mol chromium oxide of the basic chromium sulfate with subsequent adjustment of the theoretical basicity to 0 to 50% with alkali metal hydroxide or carbonate, the reaction product being added to a hide pickling liquor in the form of an aqueous solution having a chromium oxide content of at least 5% or in powder form in a quantity of 0.9 to 1.5% chromium oxide, based on hide weight, with a liquor volume less than 100%, based on hide weight, the final pH value being above 4.0 and the final temperature above 40° C.
US Patent References:
Tanning with carboxylic acid carrying ester, urethane and/or amide group
Traubel et al. - November, 1978 - 4126413

Tanning skins using polycarboxylic acid partial esters
Bockelman et al. - July, 1978 - 4101271

Tanning of hides
Backer et al. - August, 1977 - 4042321


Inventors:
Wehling, Bernhard (Bergisch-Gladbach, DE)
Makowka, Bernd (Bergisch-Gladbach, DE)
Klein Deceased., Heinz-gunter (late of Bergisch-Gladbach, DE)
Klein, Heir Gertrud (Cologne, DE)
Rosentreter, Helga (Leverkusen, DE)
Application Number:
07/231233
Publication Date:
04/24/1990
Filing Date:
08/11/1988
View Patent Images:
Download PDF 4919680 PDF help
Export Citation:
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Assignee:
Bayer Aktiengesellschaft (Leverkusen, DE)
Primary Class:
8/94.270
Other Classes:
8/94.260, 8/94.250
International Classes:
C14C3/06; C14C3/00; C14C3/06
Field of Search:
8/94.26, 8/94.27, 252/8.57
Foreign References:
DE3636002 April, 1988 89/427
FR2271290 May, 1975
Primary Examiner:
Lieberman, Paul
Assistant Examiner:
Mcnally, John F.
Attorney, Agent or Firm:
Connolly, And Hutz
Claims:
What is claimed is:

1. In an improved process for the chrome tanning of pickled hides with a tanning agent comprising a reaction product of a basic chromium (III) sulfate and aliphatic C4 -C6 dicarboxylic acids or salts thereof,
the improvement comprises preparing said reaction product in an aqueous solution from basic chromium (III) sulfate and 0.2 to 0.8 mol of the aliphatic dicarboxylic acids per mol chromium oxide of the basic chromium sulfate to 50° to 100° C. over a period of 30 to 180 minutes with subsequent adjustment of the theoretical basicity to 0 to 50% with alkali metal hydroxide or carbonate,
the reaction product being added to a hide pickling liquor in the form of an aqueous solution having a chromium oxide content of at least 5% or in powder form in a quantity of 0.9 to 1.5% chromium oxide, based on hide weight, the liquor volume comprising less than 100%, based on hide weight, the final pH value being above 4.0 and the final temperature above 40° C.


2. A process as claimed in claim 1 wherein the reaction product is added to the hide pickling solution in the form of a spray-dried product.

3. A process as claimed in claim 1 wherein said reaction product is in spray-dried form in admixture with acid-binding agents.

4. A process as claimed in claim 3 wherein the acid-binding agent comprises dolomite.

5. A process as claimed in claim 3 wherein the acid-binding agent comprises low-reactivity magnesium oxide.

6. A process as claimed in claim 1 wherein said C4 -C6 dicarboxylic acids comprise a technical mixture of glutaric, succinic and adipic acid.


Description:
The present invention relates to an improved process for high-extraction chrome tanning of animal hides.
BACKGROUND OF THE INVENTION
Efforts to improve the environmental situation around leather factories are very much concerned with reducing the chromium content of the wastewater. In addition to the recovery of unused chromium from residual tanning and retanning liquors, high-extraction chrome tanning processes have been adopted with a view to achieving this objective (K. Faber, Bibliothek des Leders, Vol. 3, pages 158 et seq, UmschauVerlag, Frankfurt/Main, 1st Edition, 1985). In Faber excesses of chromium which are not actually required and which always have to be circulated are not used for tanning as they are in recycling processes. Instead, only that quantity of chromium which is needed to establish the desired chromium content in the leather is used for tanning. Accordingly, the residual tanning and retaining liquors contain only small quantities of chromium.
To improve the extraction of chromium, it has been proposed, inter alia, to use so-called crosslinking aliphatic dicarboxylic acids, such as for example succinic acid, adipic acid and glutaric acid, for pickling or for chrome tanning (see for example Das Leder 23 (1972), 174 et seq; Das Leder 28 (1977), 155 et seq; Leder- und Hautemarkt 30 (1978), 132 et seq).
The aliphatic dicarboxylic acids are added to the chrome tanning liquor after the chrome tanning material in the form of their disodium salts. Although the extraction of chromium is distinctly improved in relation to a conventional tanning process, the quality of the leather can nevertheless be adversely affected (cf. K. Faber, loc. cit., page 83). The distribution of chromium and dyeability are impaired, particularly with thick or unskived hides. Another negative factor is that, in the described process, the penetration of the chrome tanning agent through the skin cross-section is impeded by the presence of the dicarboxylic acids (Leder- und Hautemarkt 30 (1978) 140).
To improve the situation, it is recommended to work at final pH values in the tanning liquor below 4.0 and at final temperatures of around 40° C. However, this only provides for extraction levels of up to 95% (Das Leder 28 (1977), 157).
In addition, it is recommended to add the dicarboxylic acid salts in several portions. However, this is an additional complication of the chrome tanning process.
The difficulties described above are eliminated by the process described in German 2,424,301, in which tanning mixtures consisting of chromium(III) salts, acid-binding agents and aliphatic C 4 -C 6 dicarboxylic acids or salts thereof are initially used together with conventional chrome tanning agents for chrome tanning. To obtain high extraction, at least 1.6 mol dicarboxylic acid has to be used per mol chromium oxide in the tanning mixture for full tanning.
In addition, it is known that solutions of chromium(III) salts and sodium adipate can be used for the chrome tanning of calf skins (Journal of the International Society of Leather Trades Chemists 27 (1943), 83 et seq). In this case, however, more than 1.5% chromium oxide (based on pickle weight, corresponds to considerably more than 1.5% chromium oxide, based on skin weight) has to be used to obtain an adequate tanning effect (boil dressing). The chrome liquors used have a chromium oxide content of at most only 2.8% and are therefore unsuitable for use on a commercial scale. Where more than 1.5% chromium oxide (based on pickle weight) is available, the extraction of chromium is distinctly in excess of 1.0 g chromium oxide/l.
Accordingly, in all hitherto known high-extraction chrome tanning processes where aliphatic dicarboxylic acids are co-used, the total quantity of chrome tanning material and the dicarboxylic acids always have to be added to the liquor in unreacted form in at least two portions.
BRIEF DESCRIPTION OF THE INVENTION
It has now been found that high extraction chrome tanning with uniform distribution of the chromium throughout the leather can be carried out with only one addition of the total quantity of the chrome tanning material and the dicarboxylic acids providing the pickled hides are chrome-tanned with a reaction product of a basic chromium sulfate and 0.2 to 0.8 mol/mol chromium oxide of the basic chromium sultat of an aliphatic C 4 -C 6 dicarboxylic acid or mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTION
The present high-extraction chrome tanning of pickled animal hides is achieved with a tanning agent comprising a reaction product of a basic chromium (III) sulfate and aliphatic C 4 -C 6 dicarboylic acids or their salts wherein the reaction product is prepared in an aqueous solution from basic chromium (III) sulfate and 0.2 to 0.8 mol of the aliphatic dicarboxylic acids per mol chromium oxide of the basic chromium sulfate with subsequent adjustment of the theoretical basicity to 0 to 50% alkali metal hydroxyde or carbonate, the reaction product being added to hide pickling liquor in the form of an aqueous solution having a chromium oxide content of at least 5% or in powder form in a quantity of 0.9 to 1.5% chromium oxide, based on hide weight, with a float volume less than 100%, based on hide weight, the final pH value being above 4.0 and the final temperature above 40° C. In addition, the reaction product of basic chromium (III) sulfate and dicarboxylic aids may contain monocarboxylic acids, such as formic acid or acetic acid as masking agents.
In one preferred embodiment of the process, the reaction product used in accordance with the invention, referred to hereinafter as a chromium-dicaroxylate complex, is dried and optionally mixed with the usual acid-binding agents.
The process according to the invention is carried out in a liquor volume of less than 100% and preferably 10 to 50% (based on hide weight) at a final pH value above 4.0 and preferably from 4.2 to 4.6 and at a final temperature above 40° C. and preferably from 42° to 50° C. If the chromium-dicarboxylate complex is not used together with acid-binding agents in the chrome tanning liquor, alkalis are used in the usual way for basification to the desired pH value. The term alkali is intended to mean the hydroxides and carbonates of alkali metals such as lithium, sodium, and potassium, as well as ammonia.
The chromium oxide content of the residual chrome tanning liquors obtained in the process according to the invention is below 1 g/l.
The chromium-dicarboxylate complex is prepared by reaction of basic chromium(III) sulfates withe the corresponding aliphatic C 4 -C 6 dicarboxylic acids or mixtures thereof in aqueous solution for 30 to 80 minutes at temperatures of 50° to 100° C. The desired theoretical basicity of 0 to 50% is then adjusted with alkali solution, preferably with soda solution (for calculation of the theoretical basicity, see German 3,519,287).
The chromium-dicarboxylate complex thus obtained may be used in the existing solution for chrome tanning. In one preferred embodiment of the process, the solution is concentrated by evaporation and preferably spray-dried. The powder-form tanning material obtained in this way may be used for chrome tanning either as such or in admixture with acid-binding agents.
Suitable basic chromium(III) sulfates are the reaction products of hexavalent chromium compounds with reducing agents normally used in chrome tanning (cf. K. Faber, loc. cit., page 83). They may additionally contain monocarboxylic acids (for example formic or acetic acid) or salts thereof as masking agents.
The chromium oxide content of the solutions according to the invention should be at least 5% and preferably 10 to 15%.
Aliphatic C 4 -C 6 dicarboxylic acids are, for example, succinic, glutaric, adipic, maleic, fumaric, aspartic and glutamic acid and mixtures thereof. It is preferred to use glutaric acid and adipic acid or mixtures of these acids, optionally together with other dicarboxylic acids.
Suitable acid-binding agents (basifying agents) are, for example, dolomite, alkali carbonates and bicarbonates and magnesium oxides.
The mineral double salt CaCO 3 .MgCO 3 , which has a CaO content of 20 to 40% CaO and preferably 25 to 35% CaO and an MgO content of 10 to 25% and preferably 16 to 24% MgO, is used as dolomite.
Mixtures containing at least 40% of the total quantity of acid-binding agents used in the form of dolomite and/or low-reactivity magnesium oxides are particularly suitable.
Low-reactivity magnesium oxides are, for example, commercially available products, such as ®TANBASE (a product of Steetley Quarry Products Ltd.) or ®NEUTRIGAN MO (a product of BASF).
The chromium-dicarboxylate complexes according to the invention are also suitable for use in the retanning of chrome leathers. In this case, 0.3 to 1.5% chromium oxide (based on sharing weight) is available.
The value of the process according to the invention lies primarily in the fact that the use of the chromium-dicarboxylate complex according to the invention provides for high extraction levels in chrome tanning coupled with a particularly simple procedure involving very little effort without the quality of the leather being adversely affected. Residual liquors containing less than 1 g chromium oxide/l are obtained for only a single addition of chrome tanning material and dicarboxylic acid. It was not foreseeable that the use of the chromium-dicarboxylate complexes according to the invention would greatly improve tanning or that such high extraction levels would be obtained, despite the small quantity of dicarboxylic acid, based on the chromium available.
The process according to the invention is illustrated by the following Examples in which percentages are percentages by weight unless otherwise indicated.
EXAMPLE 1
In a 1000 liter reactor, 722 kg of a chromium(III) sulfate solution having a basicity of 33.2% (according to Stiasny) and a chromium(III) oxide content of 16.8% are heated to 80° C. 42 kg technical glutaric acid (40% glutaric acid, 30% succinic acid and 30% adipic acid) are added, followed by stirring for 30 minutes. After addition of 100 ml polysiloxane-based foam inhibitor (foam inhibitor E 100, a product of Bayer AG), 347 kg of a 3N soda solution are pumped in over a period of about 120 minutes. The reaction solution is then stirred for 60 minutes at 80° C. and has a theoretical basicity of 40% for a chromium oxide content of 10.9%. The solution is then dried while still hot in a spray dryer (entry temperature: 185° C., exit temperature: 120° C.). 490 kg chromium-dicarboxylic complex containing 24% chromium oxide and 0.4 mol technical glutaric acid per mol chromium oxide and having a theoretical basicity of 40% are obtained.
EXAMPLE 2
In a 1 m 3 stirred reactor, 735 kg of a chromium(III) sulfate solution having a basicity of 33.2% (according to Stiasny) and a chromium oxide content of 15.6% are heated to around 80° C. and reacted with 64 kg technical glutaric acid. After stirring for 30 minutes at 80° C., the chrome tanning solution (basicity 13%, chromium oxide content 15.2%) is dried in a spray dryer (entry temperature: 185° C., exit temperature: 115° C.). 485 kg chromium-dicarboxylate complex tanning material having a theoretical basicity of 13% and a chromium oxide content of 23.5% (molar ratio of chromium oxide to glutaric acid 1:0.6) are obtained.
EXAMPLE 3
In a 1 m 3 stirred reactor, 700 kg of a solution of chromium sulfate having a basicity of 33.2% (according to Stiasny) and a Cr 2 O 3 content of 18% are heated to a temperature of 80° C. 43.8 kg of a mixture consisting of 32% succinic acid, 39% glutaric acid and 29% adipic acid are then dissolved therein, followed by stirring for 30 minutes. The liquid mixture obtained has a theoretical basicity of approximately 20% and a Cr 2 O 3 content of 16.9%; the molar ratio of chromium oxide to dicarboxylic acid is 1:0.4. The quantities used for the preparation of other chromium-dicarboxylate complex tanning materials suitable for use in liquid form are shown in the following Table as Examples 3a-3d (method of preparation as in Example 3).
________________________________________________________ __________________
pbw* pbw* Exam- Molar ratio Cr 2 O 3 : chromium sul- glutaric ple glutaric acid fate sol.** acid Basicity % Cr 2 O 3
________________________________________________________ __________________

3a 1:0.2 700 21.9 26.5%
17.5
3b 1:0.3 700 32.8 23.2%
17.2
3c 1:0.6 700 65.6 13.2%
16.5
3d 1:0.8 700 87.5 6.5%
16.0
________________________________________________________ __________________
*pbw = parts by weight **composition as in Example 3
EXAMPLE 4
In a 1000 liter reactor, 750 kg of a 33.2% basic chromium(III) sulfate solution having a chromium oxide content of 16.2% are heated to around 90° C. 70 kg adipic acid are then added, followed by stirring with heating for 30 minutes. After addition of a commercial foam inhibitor (E 100, a product of Bayer AG), 343 kg of a 20% soda solution are pumped in over a period of 180 minutes. The reaction solution is then stirred with heating for 60 minutes. It has a theoretical basicity of approximately 40% and a chromium oxide content of 10.4%. The still hot, liquid tanning mixture is then spray-dried (entry temperature: 180° C., exit temperature: 118° C.).
A chromium-dicarboxylate tanning material containing 22.8% chromium oxide and 0.6 mol adipic acid per mol chromium oxide and having a theoretical basicity of approximately 40% is obtained.
EXAMPLE 5
To make shoe upper leather, 100 kg cowhides (unskived) limed in the usual way are first washed for 10 minutes with 150% (based on hide weight) water at 38° C. in a tanning drum (diameter 2 m, width 2.25 m, rotational speed 12 r.p.m.). The liquor is drained off and, after deliming for 60 minutes with 2.5% ammonium sulfate, 0.3% sodium bisulfate and 0.4% formic acid in the absence of liquor, 50% water at 35° C. is added and the hides bated for 50 minutes with 0.5% of a standard commercial bate (1500 trypt. units), pH value of solution 7.5. The cross-section of the hides produces no further red coloration with phenolphthalein. The hides are then washed twice with 150% water at 20° C. and the liquor is drained off to a residual liquor of around 50%. 5 minutes after the addition of 6% sodium chloride, 1.6% sulfuric acid (diluted 1:10) are added and the hides are pickled for 120 minutes (pH 1.8).
6.7% of the tanning mixture described below are added to the pickling solution, followed by tumbling for another 20 hours. The final pH is 4.5 and the final temperature 50° C.
The residual liquor contains 0.6 g chromium oxide/l. On examination after skiving, the chrome leathers show outstanding full tanning. Finishing in the usual way gives upper leathers having a soft, full feel, a fine grain and very even coloring.
The tanning mixture used consists of:
800 parts of the powder-form chromium-dicarboxylic complex prepared in accordance with Example 1 and
174 parts dolomite.
The chromium oxide content is 19.7%.
EXAMPLE 6
7 parts of the tanning mixture described below are added to 100 parts cowhides pretreated as in Example 5, followed by tumbling for 20 hours. The final pH is 4.6 and the final temperature 48° C. The residual liquor contains 0.6 g Cr 2 O 3 /l.
The tanning mixture used, which has a Cr 2 O 3 content of 18.6%, has the following composition:
100 parts of the chromium-dicarboxylate complex tanning material prepared in accordance with Example 2,
5 parts TANBASE (Steetley, Gt. Britain) and
21 parts dolomite.
EXAMPLE 7
7.9 parts of a chromium-dicarboxylate complex solution prepared in accordance with Example 2 are added to 100 parts cowhides pretreated as in Example 5. After 1 hour, the tanning liquor is basified with 1.8% soda (dissolved in a ratio of 1:15) in 1 hour, followed by further tumbling for 15 hours. The final temperature is 46° C. and the final pH value 4.3. The residual liquor contains 0.5 g Cr 2 O 3 /l.
EXAMPLE 8
Corresponding cowhide halves pretreated as in Example 5 up to and including pickling are comparatively chrome-tanned.
100 parts hides of one half A are tumbled for 20 hours with 7.6 parts of the tanning mixture described below. Composition of the tanning mixture containing 17.4% chromium oxide (molar ratio of Cr 2 O 3 to glutaric acid 1:0.4) for A: 500 parts of a powder-form 33% basic chromium(III) sulfate containing 26% chromium oxide,
45 parts techn. glutaric acid,
86 parts sodium bicarbonate,
118 parts dolomite.
The final tanning temperature is 42° C. and the final pH value 4.3. The residual liquor contains 0.6 g Cr 2 O 3 /l.
100 parts cowhides of the corresponding half B are treated for 20 hours with 6.7 parts of the following mixture: Composition of the mixture containing 19.7% Cr 2 O 3 for B: 80 parts of the chromium-dicarboxylate complex prepared in accordance with Example 1 and 18 parts dolomite.
The temperature reached at the end of the tanning process is 42° C. and the final pH value 4.3. The residual liquor has a chromium oxide content of 0.8 g/l.
By comparison with B, the leathers of the corresponding pieces A show much poorer full tanning after skiving.
The dye finishes subsequently applied in the usual way are also distinctly less uniform in the case of A.
EXAMPLE 9
For the production of upper leather, 3000 kg cowhides (skived to approx. 3.5 mm) limed in the usual way are first washed for 10 minutes with 150% (based on hide weight) water at 38° C. in a tanning drum (diameter 3 m, width 3 m, rotational speed 5 and 10 r.p.m.). The liquor is drained off and, after deliming for 30 minutes with 30% water at 35° C. containing 2% ammonium sulfate, 0.2% sodium bisulfate and 0.2% formic acid, the hides are bated for 30 minutes with 0.5% of a standard commercial bate (1500 tryptic units), pH value of the solution 8.3.
The cross-section of the hides produces no further red coloration with phenolphthalein. The hides are then washed twice with 150% water at 20° C. and the liquor drained off to a residual liquor of approximately 20%. 5 minutes after the addition of 4% sodium chloride, 0.5% formic acid (diluted in a ratio of 1:5) and, after 10 minutes, 0.8% sulfuric acid (diluted in a ratio of 1:10) are added and the hides pickled for 60 minutes (pH 2.7). 8.1% of the chromium-dicarboxylate complex solution prepared in accordance with Example 3d are pumped into the pickling solution.
After 1 hour, the liquor is basified with 2.2% soda (dissolved in water in a ratio of 1:15) in 6 portions in 1 hour, after which tumbling is continued for 18 hours.
Towards the end of the tanning process, the temperature is 40° C. and the pH value 4.0. The residual liquor has a chromium(III) oxide concentration of 0.4 g/l.
Finishing in the usual way gives full, soft leathers distinguished by an extremely even dye finish.
EXAMPLE 10
6.7 parts of the tanning mixture described below are added to 100 parts cowhides pretreated as in Example 9 (skived to approx. 3.5 mm) in the pickling solution.
The tanning mixture, which has a Cr 2 O 3 content of 21.0%. has the following composition:
100 parts of the chromium-dicarboxylate complex tanning material produced in accordance with Example 4 and
8.5 parts TANBASE.
The final pH value is 4.3 and the final temperature 45° C. The residual liquor contains 0.5 g/l Cr 2 O 3 .
EXAMPLE 11
To make furniture leather, 300 kg cowhides (skived to approx. 2 mm) limed in the usual way are first washed for 10 minutes with 150% (based on hide weight) water at 38° C. in a tanning drum (diameter 3 m, width 3 m, rotational speed 5 and 10 r.p.m.). The liquor is drained off and, after deliming for 40 minutes with 50% water at 35° C. containing 2.5% ammonium chloride, 0.3% sodium bisulfite and 0.2% formic acid, the hides are bated for 45 minutes with 0.7% of a standard commercial bate (1500 tryptic units), pH value of the solution 8.5.
The cross-section of the hides produces no further red coloration with phenolphthalein. The hides are then washed twice with 150% water at 20° C. and the liquor drained off to a residual liquor of approximately 50%. 5 minutes after addition of 6% sodium chloride, 1.1% sulfuric acid (diluted 1:10) is added and the hides pickled for 120 minutes (pH 2.7).
6.3% of the tanning solution described in Example 3 is added to the pickling solution and, after 1 hour, the liquor is basified in 1 hour with 1.4% soda (dissolved in a ratio of 1:15), followed by further tumbling for 15 hours. The final pH is 4.2 and the final temperature 45° C.
The residual liquor contains 0.2 g/l chromium oxide. Finishing in the usual way gives furniture leather having a soft feel and very even dye finishes.
EXAMPLE 12
5.5 parts of the tanning mixture described below are added to 100 parts cowhides (skived to approx. 2 mm) limed, delimed, bated and pickled as in Example 11 in the pickling solution, followed by further tumbling for 18 hours. The final pH value is 4.5 and the final temperature 45° C. The residual liquor has a chromium oxide content of 0.3 g/l. Composition of the powder-form tanning mixture containing 19% Cr 2 O 3 :
750 parts of a chromium-dicarboxylate complex tanning material prepared in accordance with Example 4 and
151 parts dolomite.
EXAMPLE 13
500 kg wet blues (sharing thickness 1.5) are tumbled for 90 minutes in a tanning drum (diameter 2.5 m, width 2 m, rotational speed 12 r.p.m.) with 200% water at 55° C. and 2.5% (based on sharing weight) of the tanning mixture described in Example 5 with a chromium oxide content of 19.7% and then circulated for 5 minutes every hour overnight via an automatic switch mechanism. The chrome retanning liquor has a pH value of 4.6 and contains 0.1 g Cr 2 O 3 /l. The leathers are finished in the usual way for upper leather. Very evenly dyed, grain-stable upper leathers are obtained.
EXAMPLE 14
100 parts cowhides (skived to 3.5 mm) pretreated as in Example 9 are tanned in the pickling solution with 6.75 parts of the following tanning mixture:
500 parts of the chromium-dicarboxylate complex tanning material produced in accordance with Example 1 and 101 parts dolomite.
Cr 2 O 3 content: 20%.
After tumbling for 12 hours, the final temperature was 42° C. for a final pH value of 4.1. The liquor contains 0.9 g Cr 2 O 3 per liter.





Tawing is a method that uses alum and aluminum salts, generally in conjunction with other products such as egg yolk, flour, and other salts. The leather becomes tawed by soaking in a warm potash alum and salts solution, between 20°C and 30°C. The process increases the leather's plyability, stretch, softness, and quality. Adding egg yolk and flour to the standard soaking solution further enhances its fine handling characteristics. Then, the leather is air dried ("crusted") for several weeks, which allows it to stabilize. Tawing is traditionally used on pigskins and goatskins to create whitest colors. However, exposure and aging may cause slight yellowing over time and, if it remains in a wet condition, tawed leather will suffer from decay. Technically, tawing is not tanning.[3]
Depending on the finish desired, the hide may be waxed, rolled, lubricated, injected with oil, split, shaved and, of course, dyed. Suedes, nubucks etc. are finished by raising the nap of the leather by rolling with a rough surface.

Enzymes in leather production

Enzymes in leather making
Enzymes have an important role in leather manufacture and the use of biocatalysts is now considered to be state-of-the-art for the processing of animals skins and hides. There is very important use of them in leather industry in soaking, liming, especially in batting.Enzymatic liming isolated bacterial and fungal proteinases, which are also used in combination.
The most important enzyme types for leather processing are proteases and lipases, which are active against protein and fat components of the skin respectively. Other enzyme activities against other biological components present in the skin may also present future opportunities for green processing, especially in the beamhouse. Currently proteases are used extensively for the soaking, liming and bating operations and lipase formulations are commercially available to assist with the dispersion of natural fat within the skin substrate.
Research into the use of enzymes for other applications include the use of transglutaminase to facilitate tanning and dyeing reactions and phospholipase to target specific complex lipids such as sebaceous grease has also shown promise. In addition there has been a renewed emphasis on the use of enzymes to add value to waste products from the leather making process; examples include the use of lipases to produce biodiesel from waste animal fats and the use of a thermophilic protease to convert waste protein to bioethanol. The use of proteases to recover chromium from chrome containing protein waste has been the subject of considerable research.
Whilst commercial enzymes are a staple component of many commercial leather processing systems, their use is often feared due to the fact that good process control is required to both optimise their activity and prevent side activities which can cause complications such as grain damage. Furthermore, in view of the fact that enzymes are biological molecules, they are sensitive to their environment in terms of both physical conditions and chemical content and concentration that may act as both activators and inhibitors of the enzyme. An important consideration for enzyme activity is their local environment which is governed by the chemicals added to the processing vessel. Typically, this could include biocides, surfactants, metal cations and specific anions such as sulphide and chloride ions, all of which may have either a positive (activation) or negative (inhibition) effect on activity (see Figure 1).
Whilst there are a number of factors to take into consideration when handling and using enzymes, if used appropriately their benefits far outweigh any sensitivities associated with their use and often the results achieved are not possible with simple chemical systems. This is particularly relevant with properties such as softness, area yield and uniformity of the resulting leather.
One area of particular value in terms of environmental improvement is in the unhairing process. Chemical unhairing of cattle hides relies on significant concentrations of alkali, most usually calcium hydroxide which has a very low solubility, and sulphide based depilatory chemicals, both of which contribute a significant environmental burden.

Process but its mean purpose is same for unwanted protein decomposition such as albumin, gelatin and opening up of collagen protein.The process of converting hides and skins into leather involves a sequence of complex chemical reactions and mechanical processes. Although the leather industry is environmentally important as a user of a by-product, it is perceived as a consumer of resources and a producer of pollutants. In order to reach a position of sustainability, the industry must aim to reduce the consumption of chemical, water and energy resources. The impact of this processing on the environment and the safety of the resulting leather to be used throughout the supply chain to the end consumer is related to the chemical applied, the raw materials used and the effluents, waste and emissions generated through-out processing. Provisions to control these outputs and ensure eventual consumer
safety are, therefore, paramount and at the forefront of the
consumer products industry.
With the ever increasing emphasis on cleaner production, sustainable processing and greener materials, the application of enzymes to both replace and enhance chemical systems has never been more relevant. Enzyme systems that can minimize the effluent burden and replace chemicals which have an undesirable environmental profile will become of increasing interest. In an environment where brands and retailers are keen to demonstrate good environmental credentials, material selection based on green criteria will become even more important.
Green chemistry, also called sustainable chemistry, is a chemical philosophy encouraging the design of products and processes that reduce or eliminate the use and generation of hazardous substances. Green chemistry embraces many of the chemical disciplines including inorganic chemistry, organic chemistry, analytical chemistry and biochemistry and its major application is in industrial processing.
The application of enzymes fits many of the principles of green chemistry. The world market for industrial enzymes was estimated as $2.3 billion in 2008 and is estimated to rise at a growth rate of 4% per annum to $2.7 billion in 20121.

Catalytic effect
Enzymes are vital for sustaining life; without those chemical reactions in biological systems would rarely occur. Enzymes, therefore, act as powerful catalysts and are capable of increasing the rate of reactions by at least a factor of 1 million. Enzymes are generally small globular proteins, although some structural proteins such as the protein filaments of muscle can also have a catalytic role. Enzymes have a number of advantages over their chemical counterparts in that they are highly specific, operate at low temperatures and at atmospheric pressure and act rapidly. Furthermore, being diverse, they can be used over a wide range of temperature and pH conditions and can, therefore, be selected or even engineered for a specific purpose. There are thousands of known enzymes which, coupled with the capabilities of genetic manipulation and protein engineering, make the possibilities for enzyme technology almost limitless.

Conclusion
Enzymes have been used successfully to aid unhairing either as a pre-treatment in the soaking process or as an addition or pre-cursor to the liming process. When used effectively, enzymes can both speed up the process and reduce the amount of chemicals used with the resulting hides often being cleaner.
There remains much interest in the future direction of enzyme research for the leather industry. Based on the understanding that enzymes are available to carry out almost all chemical reactions, the future options for leather applications are considerable. Enzymology and green chemistry will continue to play a major part in the evolution of the leather making process, ensuring cleaner processing and the production of greener materials.
Reference:
1. BCC Research Report B10030E, 2007.

Leather for safety and work protection

Leather for safety and work protection
All leathers of this group are designated as workers` protective leathers (in German: ASA leather). Protection and safety leathers have to meet very high requirements depending on their use, e.g. compact, firm texture, high fastness to abrasion, good softness, high distension, good stability under radiant heat, high resistance to naked flames or glow heat and to the action of chemical. Special DIN standards exist for these leather sorts with distinctions made according to use in dry or wet areas, light or heavy mechanical loading and use in the industrial sectors mining, construction, non-metallic mineral industry.
The most important quality requirements for safety leathers for footwear:
Test Requirement
Shaft upper material----- insole leather-------- lining tongue
Thickness min.................... min........................... min
For dry areas -.........................2.0 ...........................0.8mm
All other areas -.......................... 2.5........................... 0.8mm.
Ladies` footwear 1.5mm..................... -............................. -
Men`s shoes 1.8........................... - ...............................-
Men`s boots 2.4.......................... - ................................ -
Abrasion - ............................max.5% .................... -
Distension of grain min.7.4mm ................. -...................... -
Split tear force min. 100 N................ - .......................min. 18 N
water vapor permeability min.0.85 mg*h-1 -cm-2 .. - .............2.0 mg *h-1 *cm2

Water absorption - .............................. after 8 h35%..............-

Release of water - ............................after 16h min 40 %........ -
Water proofing
(depending on type of shoe) min 60/90 min ................- ............................-

Water penetration < style="color: rgb(51, 51, 255); font-weight: bold; font-style: italic;">Protective gloves
Requirements of the leather the thickness of leather firmness and softness varies considerably depending on the field of application proper safe handle good fatness to cleaning are fixed in the standard and should be observed.
Safety clothing
in this group includes leathers which protect large parts of the body such ass safety suits leather aprons lap leathers protective leathers for the head or face chest protections and in a wider sense also the protective suits for motor cyclists made of special garment leathers requirements of the leathers in greater thicknesses chiefly made by pure chrome tanning with moderate fat liquoring they should receive a water repellent treatment for use in wet areas special surface finishes for instance containing reflective aluminum powder are applied to protect against high temperatures from radiant heat hygienic wearing properties should also be taken into consideration when making leathers for safety clothing it is important that they have a high capacity for absorbing and releasing transpiration under the effect of high temperatures

Leather for safety shoes

Requirements of the leather: only grain leather may be used to make safety footwear. A light correcting buffing of grain is permitted. Leathers used for insoles, lining and tongues must not be purely chrome-tanned.

Leather industry news

Pakistan tanners visit South East Asia
Pakistan/Vietnam/Indonesia
Published: 11 February, 2010
Eleven member tanners of Pakistan Tanners Association (PTA) led by their chairman, Gulzar Firoz, visited Vietnam and Indonesia between February 1-6 says a press release from the PTA.

The delegation visited Ho Chi Minh City where they met the Ho Chi Minh Shoes & Leather Association and other members of the association. One to one meetings were also held with buyers and successful trial orders were obtained say the PTA, with many further orders in the pipeline. The footwear industry in Vietnam is predicted to export footwear worth $4.2 billion in the future. The delegation also visited some Vietnamese based tanneries and large shoe factories.
On the second part of the trip the delegation visited Jakarta, Indonesia where they met the Footwear Association and Tanners Association of Indonesia. A detailed program was organised by the Pakistan Embassy who invited more than 50 buyers from tanneries, shoes factories and glove manufacturers to the meeting. Members of the PTA held one to one meetings and successful initial orders were placed. According to the PTA, Indonesian tanneries are producing only 30% of the leather required for their own manufacturing sectors and therefore it has great potential for selling semi and fully finished leathers into the country




Fujian authorities may compensate tanners

China
Problem facing the tanners in China for further leather industry construction work.
According to the sources in China, some members of the local authorities in Zhangpu, Fujian Province are considering stopping any further construction of the part-built tannery cluster in the area.
If this decision is confirmed and implemented it will affect a number of tanneries who have already invested significant time and funds constructing new facilities within the proposed cluster site.
It is understood that the local authorities, before they make their final decision on the matter, will have detailed discussions with the tanners who have invested in Zhangpu to hear their comments and will compensate any losses born by those tanneries if the stoppage becomes permanent.
At the moment it is not clear when this situation will be resolved one way or the
DyStar restart dye production in Leverkusen
Germany
The DyStar production facility in Leverkusen has been started again according to press statement released on October 28 by the preliminary insolvency administrator of DyStar Textilfarben GmbH & Co. Deutschland KG, Dr Stephan Laubereau. ‘We are very happy’, explained Laubereau.
First they will concentrate the production programme of dyestuffs and intermediate products for the paper, leather and plastics manufacturing industries but not for the textile industry. This contributes 20 percent of the facilities total capacity.
‘In addition we are working at full speed and checking the production of dyestuffs for the textile manufacturing industry’, said Laubereau. All 383 employees at the location in Leverkusen are involved in the restart.
Purchase agreement for DyStar executed - leather unit excluded
Germany
Operations at DyStar Textilfarben GmbH and DyStar Textilfarben GmbH & Co. KG at the four German DyStar sites in Brunsbüttel, Leverkusen, Frankfurt am Main and Ludwigshafen are now set to restart under the new management of Kiri Dyes & Chemicals Ltd. (KDCL). The deal does not include DyStar’s leather chemical activities or the manufacturing site at Gerestried.
‘The investor has secured financing of the purchase price and also met other conditions. The purchase agreement concerning operations of the German DyStar Group, the necessary assets and the 36 international subsidiaries has been executed’, insolvency administrators Miguel Grosser from the law firm JAFFÉ Rechtsanwälte Insolvenzverwalter and Dr. Stephan Laubereau from PLUTA Rechtsanwalts GmbH confirmed on February 4. This leaves up to 750 jobs in Germany and some 2,000 jobs worldwide secure. The exact purchase price was not disclosed.
The investor, BSE-listed Indian manufacturer and supplier Kiri Dyes & Chemicals Ltd., plans to continue the sites in Frankfurt/Main, Leverkusen, Ludwigshafen and Brunsbüttel and resume production as quickly as possible. After the German DyStar Group filed for insolvency at the end of September, only the indigo production in Ludwigshafen continued without interruptions.
Meanwhile, DyStar Textilfarben GmbH was also able to carry on full operations, the global supply of dyes, additives and services for the textile and leather processing industries, under the responsibility of insolvency administrator Miguel Grosser even after opening insolvency proceedings on December 1, 2009.
Productions in Brunsbüttel, Geretsried and Leverkusen, on the other hand, needed to be halted at the end of November 2009, requiring staff involved to be laid off. Upon execution of the purchase agreement, the vast majority of the staff laid-off in total can now be reemployed at their old workplaces.
Along with the 90 jobs in Ludwigshafen, KDCL’s buyer concept also provides new jobs for around 130 employees in Brunsbüttel, some 260 in Frankfurt, including the 50 employees of DyStar Textilfarben GmbH in Frankfurt who previously performed central functions from purchasing to sales for the DyStar Group, and roughly 236 in Leverkusen.
‘From where we stand, this is a major success to be able to save four production sites in Germany with so many jobs given the current difficult economic setting’, the insolvency
administrators underlined. ‘Looked at this way and from the point of view of the creditors, Kiri’s concept was without alternative. There was no other binding offer meeting the requirements and the necessary financing conditions.’
After an intensive worldwide search for investors, three potential buyers remained in the end with whom negotiations continued. In December 2009, the purchase agreement was finally signed with KDCL. Its execution, however, was conditional on the availability of financing, the necessary anti-trust approvals, and other conditions (consent of the banking consortium and other creditors). The banking consortium and the creditor committees had already given their consent. Now, KDCL has met the financing conditions and the relevant Cartel Authorities have given their approval.
‘Synergies of both the companies, DyStar and KDCL, will provide long term sustainable and successful future to DyStar. Dystar and KDCL jointly have created competitive advantages with completion of this acquisition, which will strengthen global leadership of DyStar, and will create high values for all their stake holders such as investors, employees, creditors and vendors. DyStar will continue to operate as an independent company in the market’, said Manish Kiri, managing director of KDCL.
Further information:
Founded in Ahmedabad in 1998, Kiri Dyes & Chemicals Ltd. today is a global market leader in the manufacture and supply of dyes and intermediates, focussing primarily in the Asian and North American markets. The acquisition of the DyStar Group will provide KDCL access to new markets and customer groups, specifically in Europe.

Sadesa Sena gets gold medal
Thailand

Sadesa have 3 gold and 1 silver LWG medals
International tanning group, Sadesa announced on November 13, that their Sena tannery in Thailand has been awarded the highest-level 'gold medal' against the Leather Working Group (LWG) environmental protocol. Certification was given following a LWG leather-manufacturing audit.
Now in its fourth year the LWG environmental stewardship programme only awards the highest gold medal rating to tanneries which meet the highest environmental standards set-out in the LWG audit protocol.
Sadesa’s Sena plant in Ayutthaya, Thailand is the groups third gold medal rated tannery following awards to their Sadesa Kabinburi tannery in Thailand and Sadesa San Luis plant in Naschel, Argentina. The company also have silver medal status for their tannery in Jiangmen, China.
The LWG is made up of leading international brands, tanneries and leather chemical suppliers and aims to raise environmental standards throughout the leather supply chain.
Clariant colour forecast – autumn/winter 2010/11
First published in June 09
Within Clariant`s globally launched shoe concept, the Leather Business have launched their new shades and trends for the autumn/winter 2010/11 fashion season. The latest Global Colour Card illustrates the four stylish themes: Go West, Lakeland, Locomotive and Modern Sculpture.
They have also developed innovative colour recipes and processes to satisfy specific demands of their clients by using Clariant’s dye and pigment ranges. With this service the leather specialists from Clariant provide their customers with exclusive fashion trend information well in advance of the season.
Based on the input of internationally known trend institutes and fashion specialists, Clariant unveil four fashion themes for the autumn/winter 2010/11 season:
Go West
This theme reflects the rugged outdoor life of cowboys and ranch hands of the old Wild West with golden saddlery browns, cactus greens and blanket reds – full of winter warmth.

Locomotive
From the feeling of nature this group uses tones of dust and smoke evocative of early steam train rides with dusty winter neutrals, travel-worn effects, soft pinks, greens and browns.

Lakeland
Is inspired by wild nature from the windswept hills and stormy skies. Colours such as lichen gold and foxglove mauve contrast with a moody blue palette. It throws new light on natural tones.
Modern Sculpture
A trick of light and shadow on contemporary art sculptures contrast with sharp bright colours and harmonious dark shades. Crisp black and white add a modern edge.
Dye and pigment ranges
All four themes are illustrated on leather samples showing both wet-end formulations produced with Clariant’s range of Melioderm dyes to cover every tanner’s dyeing needs and the finishing recipes are based on Clariant’s Neosan 2000 and PPE pigment ranges.
In addition, all colours shown are pantone specific and can be easily adapted to any finishing formulation needed. Together with Pelcroma – the professional colour management system from Clariant – an accurate, fast and simple colour matching is guaranteed.

Clariant announce plant and job cuts
Worldwide
Clarinet has its own technical lab and its technical leather staff in all over the leather industrial world.
Clariant, the specialty chemicals maker which includes leather chemicals, announced on November 19 plans to further optimise their global production network in order to address overcapacities and to reduce costs.
The proposals are the first conclusions of Clariant's 'Global Asset Network Optimization' (GANO) project, which comprises a detailed evaluation of Clariant's entire production network. The sites nominated for closure are Huningue, France; Pontypridd, UK; CIVAC, Cuernavaca in Mexico; and parts of two plants at Clariant sites in Germany, at Gendorf and Frankfurt. In addition, Clariant will now initiate an evaluation of all strategic options for its site in Onsan, South Korea.
Approximately 570 jobs worldwide will be affected by the proposals. Clariant has entered into consultation with employee representatives and authorities in the affected countries. The company is committed to treating all employees in a fair and transparent manner.
Project GANO is part of a wider restructuring program at Clariant aimed at closing the gap the company has compared to peers regarding several key performance indicators. The Project addresses the structural deficits of Clariant's production network as well as long term overcapacity issues. It will continue to identify further optimisation potential.
Full implementation of the initial Project GANO proposals affecting the nominated sites, including transferring production to other parts of the Clariant site network, is expected to be completed between 2011 and 2013. The restructuring costs amount to approximately CHF 150 million (€99 million), the vast majority of which will be made in 2009 and 2010.
Clariant ceo, Hariolf Kottmann commented: ‘As we have stated 2009 and 2010 will be years of restructuring for Clariant. Project GANO is a key component of that process. Once completed, it will significantly improve the efficiency of our production network and increase Clariant's competitiveness.'
Specific information on how the cuts will affect the leather chemicals business to follow.
Clariant team-up with Modeurop
Worldwide

Clariant's global colour concepts
Modeurop, the fashion forecast group at DSI (Das Schuhinstitut) and Clariant, the maker of colorants and chemicals for the dyeing, tanning, retanning and finishing of leather, have established an innovative, colour forecasting partnership, it was announced on December 3. This cooperation will provide tailored, reliable and consistent colour forecast to the footwear leather processing industry. It targets the entire value chain, from tanneries through to shoe manufacturers and retailers.
The cooperation between the two partners will bring considerable benefits to shoe makers and their suppliers. Shoe manufacturers and tanneries can be provided with information on colour and trends well in advance of the season. In the future all Clariant colour charts will include Modeurop specified colours. Thanks to Clariant’s international presence, Modeurop’s colour information will now reach the most important tanneries worldwide. Marga Indra-Heide, fashion consultant at Modeurop, comments on the cooperation agreement made in October 2009: ‘As a result of our partnership with Clariant, Modeurop colours have been elevated onto the prestigious global stage, adding an international dimension to our business.’ Clariant have years of expertise in colorants and chemicals for leather manufacturing.
Clariant’s leather chemicals lend the various shoe leather grades the properties that are highly valued by the industry and consumers, such as abrasion resistance, lightfastness, water repellency or tear strength. Within the scope of its worldwide Global Shoe Concept, Clariant already offers its customers from the shoe leather industry a world-established fashion trend forecast also interpreting colour previews, future trends and effects on leather.
‘The cooperation with Modeurop in the field of colours provides real added value for our customers in the shoe leather upper business, and is a further piece in the overall mosaic of our Global Shoe Concept’, explains Ralph Walter Schneider, Clariant’s head of PM Finishing.
Famous Vic tanners scale down
Spain
The Catalonian town of Vic in Spain has one of the highest tannery concentrations in the country but has seen some of its most famous names scale back their activities this year.
The oldest and once largest tannery in the town, Colomer Munmany have dramatically reduced their processing of sheepskins especially doubleface in the town since their JV with Chinese processor, Henan Prosper was announced a year ago. The Chinese hold a 90% stake in the recently formed Colomer Moda. Much of the processing equipment from Vic has now been transferred to the new plant in China which will begin operation early next year, leaving an R&D facility in Vic. Leather International contacted Colomer Munmany concerning the ownership of other elements of business such as Ledexport and their international processors and trading companies but no formal response was provided.
Curtidos Codina another famous name from the town have confirmed that they no longer process ovine leathers in Spain. Instead, Codina have long established plants in Brazil processing hairsheep and goat skins and are now the largest single exporter of finished hairsheep and goat leathers from Brazil. Codina Group own the Curtume Cobrasil tannery in Parnaiba, Piauí and a finishing plant situation in Novo Hamburgo, Rio Grande do Sul.
They also have established a commercial office in Dongguan, China. They supply major brands in China, Europe, Brazil and USA.
National Beef report higher profits
United States
National Beef Packing have posted a 13% increase in profits this year thanks to reduced cattle purchases, lower cattle prices and other cost cutting, according to a recent filing with the Securities and Exchange Commission.
For the fiscal year ended August 29, the Kansas City based company said net earnings were $149.2 million, compared with $124.5 million in the fiscal 2008, which was one week longer than this year's reporting period. The profit came despite a decrease in sales to $5.45 billion, some $400 million less than total revenues in 2008.
‘The decrease resulted partially from a decrease of approximately 2.5% in the number of live cattle purchased on a per week basis in addition to the additional week in fiscal year 2008’, the company stated in its filing. ‘Also contributing to this decrease was a lowering of live cattle prices of approximately 7.4%.’ Operating income was $174.7 million for fiscal year 2009, a 12.9% increase over 2008, primarily resulting from increased profitability from sales of commodity beef products, exports and value-added products. Improved profitability in commodity beef sales primarily resulted from better demand relative to the price of cattle, the company said.
National Beef includes a tanning division known as National Beef Leather processing cattle hides from their own packing plants in the USA.
Source: Hidenet.com
Stahl appoint fashion design team
Worldwide


Carmen Rimoldi and Sergio Belloni of Bianco & White
Stahl have appointed a new team of Italian fashion consultants, Bianco & White, to support their fashion design, colour and advice programme. Based in the fashion centre of Milan, the consultancy is run by Carmen Rimoldi and Sergio Belloni, both of whom have had many experience of working with the various sectors of the leather industry on a worldwide basis.
Bianco & White first appeared on the fashion scene when it was founded by Rimoldi and Belloni in July 2000. Rimoldi is a fashion, design and scene-designer graduate from NABA and an inventor of exclusive graphic images. Among her current projects are a range of specially branded shoes and bags.
Her colleague, Belloni, is a stylist for women’s shoes working with some of the world’s most prestigious brands. He is also a shoe technician. He is also an advisor to the chemical industry and to tanneries in the field of finishing and the study of new colours and products.
Together they will provide Stahl with an in-depth knowledge of colours, trends and new materials almost two years ahead of the season to which they refer. This knowledge will be invaluable for Stahl’s exclusive strategic and stylistic fashion support for contemporary leather finishing.
Belloni’s and Rimoldi’s first collaboration with Stahl will be the summer 2011 colour preview, details of which will be
ISA Tan Tec celebrate opening of new eco-tannery
Vietnam

More than 350 invited guests of the China based German leather producer ISA Tan Tec attended the opening of its new tannery in Vietnam on January 22. ISA Tan Tec are aiming to provide a new standard for sustainability in leather making combining environmental and socially responsible leather production. ‘It is surprising to see solutions for so many challenging issues put into action by the company’, said Tran Van Lieu head of Binh Duong Industrial and Export Processing Zones Authority (BDIZA), Vietnam.
The new tannery features innovative use of renewable energy and utilisation of waste heat from production processes and the company has applied German standards to working conditions, efficiency and environmental technology with the new plant. ‘For many years, we have been working on the vision of fundamentally overhauling leather production in a bid to make it green. We have now achieved that goal. With this tannery, we show how economic success goes hand in hand with ecologically and socially sustainable economic practices’, says Tom Schneider, ceo, ISA Tan Tec.
The ISA Tan Tec team would like to see the efforts put into this project serving as an example for future enterprises expanding not only into Vietnam but also other major Asian countries. At the new tannery a total of 250 employees will process twenty million square feet of leather every year for customers such as Timberland, New Balance, Keen, Patagonia and Merrell.
The guests attending the opening ceremony included Conrad Cappell, Consul General of Germany and Aneta Nikolova of UNESCAP. ‘I’m passionate about finding strong solutions which were thought not easy to implement, but ISA have managed to turn into a successful tool’, Aneta Nikolova said.
Guests at the opening were shown the creative atmosphere and the ingenious, economical use of resources, such as a windmill used for pumping water and that the wastewater is cleaned in an engineered constructed wetland and subsequently reused. Likewise, the tannery also collects rainwater for use in production processes and water is heated in a solar thermal system without CO2 emissions. A half-open bamboo wall ensures natural cooling and a pleasant temperature inside the production building.
Tom Schneider took the opportunity to thank customers and partners for their support: ‘We know that many of our friends share our vision. Without the generous support of government officials from both international and local community, the science and financial sectors, we would not have been able to achieve our goals so fast and comprehensively.’
Cotance statement on Greenpeace report
Worldwide
The Social Partners of the European Leather Industry (Cotance) addressed, in their Social Sectoral Dialogue Committee Meeting of December 15, 2009 (in Brussels), the allegations made to the leather industry in general and to certain European tanneries and their customers in particular in the Greenpeace report released over internet on the deforestation of the Amazon (http://www.greenpeace.org/international/press/reports/slaughtering-the-amazon).
They appreciate the gravity of the problem uncovered by Greenpeace and express upfront their solidarity with the objective of preserving the environment and notably the avoidance of irresponsible harm to the Amazon rainforest. The European Social Partners dissociate themselves from any form of unsustainable generation of hides and skins notably the one highlighted in the Greenpeace report.
However, Cotance and ETUF-TCL regret the distorted vision with regard to the link made in the report between the deforestation issue and the leather industry that has been further conveyed in the general press, amplifying the damage caused to the image of the leather industry and to the reputation of the people who work in the leather value chain including European tanners and their customers.
Social Partners understand that the general public deserves to know that the leather industry does not drive the demand for animal breeding and the development of herds or flocks for an increased supply of raw materials anywhere in the world and can thus not be accused of driving the deforestation of the Amazon rainforest. The supply of hides and skins is independent from the demand for raw materials in the leather sector. Hides and skins are residues produced in the process of generating food for the people. If not processed to leather, the amount of hides and skins generated by the meat industry would become a significant waste disposal problem for society in general. The leather sector fulfils thus an important societal role in the management of waste and the valorisation of a residue generating wealth and employment in the process.
Besides, tanners face a real challenge in influencing up-stream operators’ policies also because of their size and relative bargaining power with regard to their suppliers. The vast majority of the European leather sector is composed of SME’s, while the suppliers of raw materials are generally large industries.
The Social Partners of the European leather industry would welcome increased transparency in the hides and skins supply chain. Cotance and ETUF-TCL are in fact the first to call for support in improving the traceability of raw materials in the supply chain for fulfilling sustainability objectives such as the one highlighted by Greenpeace, but also others, such as those related to animal welfare. Presently, companies have difficulties in obtaining information on the concrete origin of the raw hide or skin and face problems in recognising and prevent the procurement of raw materials from unsustainable sources.
Meanwhile, the Social Partners of the European Leather industry intend to go further in their sustainability agenda by developing together an appropriate Code of Conduct for their supplies of raw materials and effective instruments for transparency on the origin of hides and skins that should allow the sector’s operators to identify the origin and communicate with the animal husbandry sector on common sustainability objectives.
Indian market on the up
India
Indian leather fair was in full swing in 2nd day too as it was in 1st day and great attraction from Indian leather producer to the world’s leather trader.
The second day of the India International Leather Fair (IILF) held in Chennai, India was just as busy as the first day on February 2. Crowds flocked to a hot and sultry Chennai Trade Centre to visit companies supplying the tanning and finished leather products industries.
Following a fall in growth in 2009 the Council for Leather Exports (CLE) have announced the market started to grow again from October 2009. 'Though exports increased towards the end of 2009 we expect the export turnover to reduce by 10% for 2009', said Habib Hussain, chairman, CLE.
Despite the fall, if the IILF is anything to go by, then the Indian leather industry should recover in 2010 and everyone Leather International spoke at the show was positive about the event and the general condition of the market. 'In recent times we have taken market share from China and a lot of business from Turkey', says Dr Zackeria Sait, regional chairman - south, CLE.
Indian tanneries produce around 2 billion square feet of leather per annum (10% of the world total) with major tanning clusters in Chennai, Ambur, Ranipet, Kolkata, Kanpur and Jalandhar. India is home to 2091 tanneries (45% in Tamil Nadu, 26% in West Bengal and 18% in Uttar Pradesh.
The final day of the IILF is due to take place on Februar
Overall slaughter decreases
Although in the month of Eid-Ul-Adha rate slaughtering rapidly increases in Islamic country but in world wide it over all does not.
Federally Inspected Slaughter in the four week period ended October 31, 2009, amounted to an average weekly kill of 640,750 (651,250 in our previous report). Last year the average for the month was 639,250.
Overall, slaughter was down 4.3% on last year. Cattle and calves on feed for slaughter at feedlots with a capacity of 1,000/plus head totalled 10.5 million head on October 1. The inventory was 1% above the previous year and included 6.42 million steers.
Export sales of raw hides
during the period under review showed China once more in their regular top position but with markedly fewer hides. China purchased 775,100 (713,300 in an earlier report and 1,074,300 previously). With Hong Kong in fifth place taking 55,500 (16,900), the region accounted for a combined total of 830,600 (730,200).
Korea was again in second place with 375,700 (266,400) followed by Taiwan with 125,300 (66,200). Next came Mexico with 62,900 (74,500).
In sixth place Vietnam came in for 36,700 (70,500); Japan 28,100 (12,900); Italy 26,500 (52,500); Canada 24,800 (14,400); Thailand 19,700 (14,800); and Brazil 6,000.
India purchased 4,500 (10,900); Tunisia 3,000; Egypt 900; and Croatia 800.
During this period Hong Kong took 2,800 kip; China 1,900 calf and Mexico 1,400 kip.
Sales of wet-blue for export during the period under review showed China back in first place with 214,400 (69,600 previously and 214,000 the period before that).
Italy took second slot with 160,000 (52,500); then Mexico with 69,800 (135,900); Taiwan 57,600 (53,800); Vietnam 48,000 (25,700); the Dominican Republic 16,000 (16,100); Korea 14,300 (18,000); Indonesia 3,600; and Japan 1,400 (9,100).