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- The Major Challenges facing the French Leather Industry
- Study on the Leaching Performance of Chrome in Waste Leather Products
- Clothing Weldability Sif ESF4011 Chrome Leather Bolero Occupational Health & Safety Products
- Apron Chrome Leather
- Conventional chrome
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- Table of Contents
- Chrome VI Audits for Leather Manufacturers
- Tanning (leather)
The Major Challenges facing the French Leather IndustryVIDEO ON THE TOPIC: How to Tan Quality Leather and Avoid Bad Leather - Saddleback Leather Co.
United States Patent Oflfice 3,, Patented Mar. Telander, Ashtabula, hio, and Melvin L. Continuation of application Ser. This application Feb. This invention relates generally to the tanning of leather. More particularly, this invention relates to an improved process of retanning chrome tanned leather in the manufacture of retan leathers.
This invention also relates to the processing of runaway liquor in preparing novel vegetable retanning compositions for the treatment of chrome leather. Vegetable tannage or mineral tannage have long constituted the major tanning processes in the manufacture of leathers of different types. Each process has its advantages as Well as limitations and the choice of method is necessarily determined on the basis of the properties of the leather desired and other considerations such as cost, availability of reagents, etc.
The vegetable tanning process, for example, is desirable particularly in the tanning of heavy leathers such as sole leather since superior Plumping and fullness is obtained thereby accounting for high yields of leather from the hide or skin stock. The rate of diffusion of vegetable tannin into hides, however, is very slow and a long time is required to sufficiently tan the hide.
The use of concentrated vegetable tanning liquors to circumvent the slow diffusion has not proven successful since the rate of combination of the tannin with the protein of the hide is greater than the rate of diffusion of the tannin into the interior of the hide.
Consequently, the outer layers of the hide become contracted to a greater extent than the inner layer and a distortion results which detracts from the appearance and value of the leather.
To overcome this difiiculty, tanners are compelled to use a multiple step process when tanning with vegetable tannins which involves the moving of the hides or skins into progressively stronger tanning liquors until they are completely tanned. In some cases, as in the tanning of sole leather, months may be required to complete the tanning of the leather. Mineral tannage, on the other hand, the most Widely used process being chrome tanning, is capable of drastically reducing the period required for tanning the hide or skin stock.
Chrome tanning also imparts to the leather the properties of greater resistance to heat and abrasion than does vegetable tanning. Although a good portion of the worlds supply of light leathers is tanned by means of chromium salts, the chrome tanning processes are incapable of producing the properties of plumpness, fullness, and other characteristics required for many specific uses for leather.
Several approaches have been used in attempting to overcome the above difiiculties and limitations. One approach has been the search for new types of tanning materials commonly referred to as syntans. Another has been the use of combined chrome and vegetable tannage using, for example, a chrome tanning operation first and then vegetable tannage or vice versa to supplement or combine the characteristics or results inherent in each tanning process.
The products from such combination type of tanning process are called retan leathers. In effect, the chrome tanning step when used in combination with a vegetable tanning step makes it possible to more or less average the advantages and disadvantages of both tanning procedures. The chrome tanning or pretanning thus enables a rapid penetration of the mineral tanning liquor into the entire mass and imparts to the leather the improved resistance to heat and abrasion.
The chrome leather is then subjected to the action of fresh vegetable tanning liquors to permit the desired degree of retanning to occur whereby a plumper and fuller retanned product is obtained. Other changes such as properties pertinent to tooling "and embossing the leather are also significantly improved by the retanning. One basic disadvantage of the combination tannage is the increased cost of tanning reagents inasmuch as both the chrome tanning and vegetable tanning reagents are necessarily involved in the process.
The cost of the relatively expensive vegetable tannin materials is a particularly important factor in the production of retan leathers. We have now found that chrome leather can be retanned by treating the same with concentrated runaway liquor.
Surprisingly enough, this spent vegetable tanning liquor which heretofore has been considered to be of no value for further vegetable tanning purposes has now been found to be an excellent retanning agent for chrome leather.
Until the present discovery, the discarding of this runaway liquor has constituted a major waste disposal problem. In addition to eliminating this waste disposal problem, the newly discovered utility of this formerly rejected material now makes possible the retanning of chrome leather at a substantially lower cost.
The retan leather made in accordance with the present invention is not only as good as the chrome leather conventionally retanned with fresh vegetable tanning liquor but is actually superior in so far as qualities and properties such as grain texture and strength, yield of leather breaking characteristics, feel, etc. The runaway liquor concentrate described hereinafter in detail has also been found to be highly desirable as a color mordant for chrome-tanned leather.
It is therefore an object of this invention to provide a process for retanning chrome leather without requiring the use of fresh vegetable tannin liquors heretofore used in the process for vegetable retanning of chrome leather. It is another object to provide a process for retanning chrome leather wherein runaway liquor extract can be utilized as a complete or partial replacement for natural vegetable tanning substances as the retanning agent.
It is another object to provide novel retanning mixtures useful in the treatment of chrome leather. It is a further object to provide a process for retanning chrome leather at a substantially reduced cost. It is yet another object of this invention to provide a process for applying spent vegetable tanning liquors after treatment of the same to retanning and mordanting of chrome leathers thereby eliminating a Waste disposal problem.
Yet another object is to provide a chrome leather retanning process which results in the production of retan leathers having superior tooling and embossing characteristics as well as improved grain texture and strength, yield, feel, appearance, etc. Yet another object is to provide a process for treating runaway liquor for converting the same to a desirable form for utilization as a vegetable retanning and mordanting agent for chrome leathers.
Further objects ment. Conventional vegetable tannery liquor is made up of extracts from quebracho, chestnut, wattle, valonia, myrobalons, spruce, gambier, divi-divi, and other nut, wood, root or bark concentrates. Following its conventional use in vegetable tannery operations wherein the active tannin content is considered substantially exhausted to a degree wherein the liquor is of no further use for tanning purposes, this material depending upon its initial composition and the vegetable tanning process in which it has been used has the following approximate composition:.
Total solids percent 2. The spent vegetable tanning liquor constitutes the socalled runaway liquor the bulk of which is routinely discharged to sewers thereby creating a serious disposal problem. Usually, active remedial steps involving substantial cost must be taken to eliminate odor and pollution problems created by the waste disposal.
Some limited uses of the material have been heretofore made as, for example, in connection with the treatment of boiler water, oil well applications, leather dressing, etc. This invention is based in part on the discovery that runaway liquor concentrates prepared in accordance with the process hereinafter described in detail can be used as a retanning and mordanting agent for chrome leather. Although this material is by no means a suitable substitu te for fresh vegetable tanning liquors in so far as vegetable tanned leather is concerned, it has now been found to be an excellent vegetable retanning agent for chrome leather in place of the fresh vegetable tanning liquor heretofore required for the purpose.
In other words, despite the fact that the components in the concentrate are substantially rejected in conventional vegetable tanning operations, in the case of chrome leather, an almost complete takeup of the tannin, insolubles and non-tannin occurs. Thus, the processed runaway liquor when used for retanning chrome leather functions in a manneli similar to fresh vegetable tanning liquors'resulting in an almost complete exhaustion of the liquor- In.
The mechanism for this phenomenon is not clear-;. Atthe same time, chrome leather treated with the runaway liquor extract is of better quality than when retanned with natural vegetable tanning agents in accordance with conventionalpractice. This improve ment of quality of the finished leather is particularly evident in the flanks and heads as compared to leather retanned with conventional fresh vegetable extracts.
The, treatment of runaway liquor or vegetable tanning sewer liquor prior to its utilization as a retanning or rnorda nting agent for chrome leather can be readily achieved on a commercial basis in conventional equip- Prior to the processing of the waste liquor, the discharge liquor from thevegetable tanning rocker sec tions is collected in a tank and allowed to settle for a brief period.
Prolonged standing and the use of dirty tanks should be avoided to prevent excessive contamination and bacterial decomposition which cause undesirable odor development. Solid materials of relatively large particle size such as fibrous flesh materials, bark fragments, etc.
In order to reduce handling and shipping costs, it may be desirable to evaporate the runaway liquor extract to complete dryness or powder form by conventional spray or flash drying methods. The concentrate in either the liquid or powder form can be readily reconstituted or adjusted to any desired total solids level prior to its mordanting and retanning usage without any loss or. For evaporating or condensing runaway liquor, conventional equipment such as single stage, double stage or multiple stage evaporators can be used.
Triple effect vacuum evaporators have been found to be especially practical for processing runaway liquor in commercial quantities. The condensation or evaporation treatment produces certain changes in the non-tannin content of the liquor. Although the mechanism for the changes is not fully understood, it can be readily determined by standard tannin analyses and evaluation of the purity that a conversion of non-tannins to tannin actually occurs.
If no changes in non-tannins and insolubles took place, the composition of the tannin in the concentrate would vary only in proportion to the extent of concentration. Such is not the case, however, as seen from the following data which are representative of the values at various stages of the treatment of runaway liquor as compared to calculated values which would otherwise be expected if no conversion of non-tannin to tannin occurred:. Although the conversion of insolubles and non-tannins materials varies somewhat depending upon the starting material as determined by the composition and usage of the original vegetable tanning solution, the increase in active tannin is nevertheless consistently obtained by virtue of the evaporation process.
As previously indicated, the non-tannins and insolubles present in the concentrate are also consumed in the retanning process. Therefore the high degree of retanning action achieved by the use of runaway extract cannot be explained solely on the basis of the tannin content alone.
Although the mechanism of the retanning action is not clearly understood, it is believed that the non-tannin content acts as a buffer thereby preventing drawing of the grain of the leather particularly in the neck and flank portion of the hides.
The use of the concentrates prepared from difierent sources in accordance with the method herein disclosed occasionally results in considerable variation of the color of the finished leather when applied to the retanning of chrome leather. For eliminating or minimizing this difficulty, changing the dyes used in coloring the leather has been found to be helpful. Color improvement may be more effectively achieved however, by lowering the pH of the concentrate. Further improvement of coloring properties and characteristics is obtained by adding a sequestering agent which modifies the effect of iron and other metal salts present in the concentrate through its chelating action.
The use of both measures are preferred for establishing a firmer combination of the retanning ingredients in the leather and improving the coloring properties of the concentrate. The acids which may be used for lowering the pH may be either organic or mineral acids including acetic, oxalic, lactic, formic, citric, hydrochloric, sulfuric, phosphoric acids, etc.
Very good results are obtained, for example, by the use of combinations of acids such as acetic-hydrochloric or sulfuric-oxalic, etc. The amount of acid to be used can be varied rather broadly but the pH adjustment should not be excessively low below 4.
The use of runaway concentrate at a pH below about 4. The adjustment of pH between the range 4. The acid or acids used for adjusting the pH of the extract may be incorporated into the concentrate either during the condensation process or prior to the utilization of the concentrate in the retanning or mordauting process.
Commercially available sequestering agents of the ethylenediamine tetraacetic acid type and its salts are especially desirable. Excellent results are obtained by the use of the various sodium salts thereof. The quantity of sequestering agent to be added to the concentrate can be varied broadly as from.
Good results are obtained when from. This concentrate referred to as first run extract is allowed to settle in a tank whereby the coarser insoluble particles become separated and are removed. Sufficient acetic acid is then added along with about. During the evaporation process, conventional antifoaming agents can be used if desired to eliminate or minimize losses of the material caused by excessive foaming.
A further modification consists of the addition of a masking agent to improve the odor characteristics of the product. Preferably, the masking agent should also possess bactericidal properties for improving the keeping qualities of the concentrate. Silicofiuoride salts, phenolic compounds, mercurials and other preservatives can be used but it is preferred to use phenolic compounds such as phenol, cresol, etc.
Mixed cresols or cresylic acid are particularly desirable when added in concentrations up to about 0.
Accordingly, it is not intended to be limited thereby as to the specific degree of concentrations of the runaway liquor and to the manner in which the concentration is achieved. For treating chrome leather with runaway liquor concentrate or extract, any of the conventional vegetable retanning procedures for chrome leather can be used. The concentrate may be used as is, depending upon its total solids content as determined by the degree of concentration or it may be diluted or reconstituted for use in the retanning process.
The extract can also be used alone or with other materials as a vegetable retanning and mordanting material on chrome leather. The pH of the leather can be adjusted during the course of the retanning procedure as desired without impairing the retanning properties of the extract or causing undesirable pile-up of the grain. Organic acids such as acetic, formic, lactic, oxalic, etc.
Using the best quality material, we are successfully supplying a wide range of Apron Chrome Leathers to our esteemed clients all over the country. We procure these leathers from our trusted vendors in the market. Our offered leathers are tested by our skilled professionals to ensure the superior quality. These leather aprons are used in various cooking and industrial applications.
Study on the Leaching Performance of Chrome in Waste Leather Products
Tanning is the process of treating skins and hides of animals to produce leather. A tannery is the place where the skins are processed. Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition , and also possibly coloring it. Before tanning, the skins are unhaired, degreased, desalted and soaked in water over a period of 6 hours to 2 days. Historically this process was considered a noxious or "odoriferous trade" and relegated to the outskirts of town. Traditionally, tanning used tannin , an acidic chemical compound from which the tanning process draws its name.
Clothing Weldability Sif ESF4011 Chrome Leather Bolero Occupational Health & Safety Products
Journal of Biotechnology and Biomedicine. O Box: Journal of Biotechnology and Biomedicine 2 : Tanning system was conducted in industrial research consultancies center, Sudan.
The peculiar mechanical properties of leather depend on the hide composition, a dense collagen feltwork. Unfortunately, due to their proteic composition, rawhides may undergo microbial attack and biodeterioration. Over centuries, different processes and treatments brining, vegetal or chrome tanning, tawing, etc. Nevertheless, even present-day rawhides are subjected to biological colonisation, and traces of this colonisation are clearly shown in Chrome III tanned leathers in the wet blue stage , with obvious economic damages. The colonisation traces on tanned leathers consist of isolated or coalescent red patches, known as red heat deterioration. Parchments are rawhide products, too; they derive from another manufacturing procedure. Even parchments undergo microbial attack; the parchment biodeterioration seems comparable to leather red heat deterioration and is known as purple spots. Recently, an ecological succession model explained the process of historical parchment purple spot deterioration; the haloarchaea Halobacterium salinarum is the pioneer organism triggering this attack. The marine salt used to prevent rawhide rotting is the carrier of haloarchaea colonisers Migliore et al. A bioinformatic comparison between chrome tanned leather vs.
Apron Chrome Leather
Conventional chrome tanning methods employed in the leather processing industry subject the hides and skins to treatment with a wide variety of chemicals and passage through various unit operations. All this involves an enormous amount of time and they contribute to an increase in COD, chlorides, sulfates and other mineral salts, which end up as effluent. But, perhaps more alarmingly, the process uses profuse quantities of water in areas where there is rapid depletion of ground water. To overcome this, a process has been explored to reduce water usage, vis-a-vis deliming, pickle and basification-free chrome tanning for the stabilisation of cow, buffalo and goat skins.
The leaching experiments of finished pigskin, finished cowhide and finished sheepskin are conducted in this essay with liquor of different pH to research the leaching performance of chrome. After continuous leaching of hours, it turns out that chrome is leached out most under the effect of the liquor whose pH is 2, and it is intermittent. Comparing the content of extracted chrome, it turns out those samples, treated with liquor whose pH is 2, has increased values, which proves that the stability of chrome in leather declines. Request Permissions. China leather, , 41 3 : Kolomaznik, M. Adamek, I. Leather waste— potential threat to human health and a new technology of its treatment, Journal of Hazardous Materials, : — Study on the leaching experiment of hazardous trace elements in coal-fired residues: Review [J]. Leaching experiments on heavy metal Mo release from sharn molybdenum ore tailings[J]. Ecology and environment, , 17 2 :
United States Patent Oflfice 3,, Patented Mar. Telander, Ashtabula, hio, and Melvin L. Continuation of application Ser. This application Feb. This invention relates generally to the tanning of leather.
The chrome extraction from leather waste takes place by alkaline means without heating, or by acid means with heating, and in both processes, the leather is not dissolved on the solution, maintaining a solid st-ate, and co- products generated in this process have value for animal feed industry or for agriculture, as a fertilizer. The leather without chrome, and on solid state, is a protein with high value for agriculture, the organic-free protein chrome is utilized as raw material for the chemical industry. Organization of the United Nations, the environmental problems related to leather processing, that demands hazardous chemical products such as chrome, are increasing. However, one of its main drawbacks comes from the toxicity of its hexavalent form, such as chromates, due to its solubility in physiological pH and capacity of bioaccumulation in water organisms. However, chrome recovery via incineration presents a restriction regarding to the mixture of waste from tannery and from other sources. Generally, solid tannery waste must not be mixed with other waste, in order to avoid diluting the chrome; this way, the feasibility of the chrome incineration involves the need of accumulating large quantities of chromed waste, to attend the concentration limits of Chrome present on waste treated in an incinerator. Waste containing chrome can be incinerated only with a very strict and expensive treatment of atmospheric effluents, to attend the applicable law, and it still does not ensure the complete recovery of the Chrome. Due to the difficulty of recovering the chrome from the waste, currently, these wastes are commonly sent to industrial landfills.
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Chrome VI Audits for Leather Manufacturers
The Conseil National du Cuir CNC is an inter-professional organisation that brings together 19 professional federations from the leather industry. It represents the entire French leather industry, ranging from animal breeding to the distribution of finished products, including raw materials processing and the manufacturing of finished products. In , they exported goods to a total value of 9.
Account Options Connexion. Hugh D. Page Industry and Commerce.
General Profile Debra Osinsky. Tanning and Leather Finishing Dean B. Fur Industry P.