Produce semi-finished leather
AI Topper A third-generation family business spanning six decades, AI Topper has developed from its beginnings as a merchant trader of Raw Sheepskins and Hides in Australia, to its standing today as a market leader, handling all stages of production from Raw Salted Stocks through to Finished Leathers. We have the knowledge, capability and facility to serve the footwear, furniture, accessories, sporting goods, and automotive crust markets. Over the years, additions to the tannery have made it one of the larger installations in Australia. Conceria Montebello Conceria Montebello produces bovine leathers, full grain and suede for the fashion sector. Both basic and sophisticated articles are designed and produced in collaboration with the most prestigious brands, suited for clothing, leather goods, footwear and interior design. Running since , exporting in 3 continents.VIDEO ON THE TOPIC: How to Tan Quality Leather and Avoid Bad Leather - Saddleback Leather Co.
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Setting an example
In the leather industry, the readily perishable raw material, the animal hide, must be converted into a biologically and mechanically stabilized state in order to be storable and transportable. For this purpose, semifinished leather products are produced by pretanning, as a rule by the following two, basically different processes:. On the one hand, by pretanning with corrosion-containing tanning agents to give the wet blue semifinished product and, on the other hand, by chromium-free pretanning to give the wet white semifinished product.
Wet blue semifinished products have the disadvantage that they are already chromium-containing, i. Resoftening without a reduction in quality is not possible. In contrast, wet white semifinished products have the advantage that they are not contaminated with the heavy metal chromium, but they are very susceptible to attacks by microorganisms, in particular by molds, and are therefore considered to be virtually untransportable. Known semifinished leather products have to be biologically stabilized with addition of biocides.
The main problem associated with known semifinished leather products is therefore that the water content must not fall below a certain level if the quality of the leather to be produced in the subsequent process steps is not to be adversely affected.
On the other hand, however, this still relatively high water content leads to correspondingly high transport costs and in particular to limited transportability and storability since such semifinished leather products are ideal culture media for microorganisms. There has therefore been no lack of attempts to provide processes for the production of semifinished products, which processes meet these contradictory requirements, i. However, this process has the substantial disadvantage that substances which have surface-active properties and determine the basic character of the semifinished product and adversely affect subsequent tanning steps, for example by influencing the fat distribution, are introduced for stabilizing the semifinished product.
It is an object of the present invention to provide a process for the production of a biologically stable semifinished leather product, which process is environmentally friendly, does not adversely affect the quality of the semifinished product and end products produced therefrom and does not impose any restrictions at all in the further processing.
It has surprisingly been found that semifinished leather products dry with a loose structure and isolated fibers as a result of pretanning with the use of finely divided clay minerals having the particle diameter as defined above and, after drying, can be readily resoftened with pure water without additives.
Clay minerals having the particle sizes defined above form stable formulations for use in chromium-free or chrome tanning which ensure improved properties of the leather obtained thereby.
By means of this treatment, it is intended to ensure that the clay mineral is delaminated until the particle size no longer changes. The determination of the particle sizes and particle size distribution was effected according to ISO by combined laser light diffraction and light scattering using a Malvern analysis instrument from Malvern.
It is assumed that, for the action of the clay minerals having the particle sizes defined above, the interaction thereof with the collagen chains of the hide is essential. This interaction is possible, for example, via hydrogen bridges between collagen and the surface hydroxyl groups of the clay minerals. It has surprisingly been found that clay minerals having the defined particle sizes are irreversibly incorporated into the hide. Clay minerals are weathering products of primary aluminosilicates, i.
Silicon is surrounded tetrahedrally by four oxygen atoms, while aluminum is present in octahedral coordination. Clay minerals predominantly belong to the phyllosilicates, also referred to as sheet silicates or leaf silicates, but in some cases also to the band silicates cf. Rompp Chemie Lexikon, 9th edition, , pages and For the novel formulations, it is particularly advantageous if the clay mineral is a phyllosilicate.
Preferably, the phyllosilicate may be a kaolinite, muscovite, montmorillonite, smectite, saponite, vermiculite, hallosite or bentonite, in particular a hectorite or an organically modified variant thereof.
Particularly good results are obtained if substances which, owing to their chemical structure, are capable of forming strong hydrogen bonds with the clay mineral, in particular urea or urea derivatives, alcohols, polyols, propylene carbonate, organic amides, urethanes, saccharides or derivatives of saccharides, in particular nitrocellulose, sulfite cellulose or ethylhexylcellulose, are added to the clay minerals before or during the use thereof as tanning agents.
Inter alia, the delamination of the clay mineral, in particular of the sheet silicate, is supported by this treatment. In addition to the clay mineral, a chromium-free tanning agent, preferably an aldehyde tanning agent, an isocyanate, an aluminum salt, an oxazolidine or tetrakishydroxymethylphosphonium chloride, is used for the pretanning.
By means of drying on a tenter frame, substantially flat and hence easily stackable semifinished products are obtained. A further advantage of the novel process is due to the absorptivity of the substantially dried semifinished leather product: thus, aqueous solutions of tanning assistants having poor affinity to the hide are physically absorbed and uniformly transported and distributed in the inner hide regions, which has to date lead to unsatisfactory results owing to the comparatively low chemical potential when working in an aqueous liquor.
The semifinished leather product produced by the novel process can therefore be moistened in a further processing step with an aqueous solution of a tanning assistant which is absorbed by means of physical forces, in particular osmosis, into the semifinished leather product, preferably generally aqueous solutions of proteins, in particular protein hydrolysis products, or polymers.
This can advantageously be effected simultaneously with the step of resoftening by spraying or immersion. According to the invention, a semifinished leather product which is completely open with respect to further processing to end product is thus provided. Up to the stage of the semifinished leather product, it is possible to operate in the absence of chromium, the further processing being possible either in the absence of chromium or by chrome tanning.
The semifinished leather product can be shaved either prior to drying or after resoftening, chromium-free shaving always being obtained. A further advantage is that hide defects or quality-impairing abnormalities of the hide are more readily observable on the dried semifinished products in terms of defect detection and hence the sorting with respect to hide quality can be carried out more easily, more quickly and with improved reproducibility.
A further advantage is the reduced water content, which leads to obvious economic advantages with regard to transport and storage. Butts of pickled cattle sides, split to a thickness of 3 mm were treated at a pH of 2.
After a drumming time of 90 minutes, the basicity was increased to pH 3. The morphological characteristics are shown in table 1 below. Liquor exhaustion and shavability were assessed visually according to a rating scale of from 1 to 5.
The shrinkage temperature was determined according to DIN , which was modified in the following points, as mentioned below: point 4. The table shows predominantly improved values in the liquor exhaustion, shavability and shrinkage temperature for examples E1 to E5, relative to comparative example C0.
The semifinished products obtained according to C0 and E1 to E5 were dried and then retanned. For this purpose, the hides obtained according to comparative example C0 and examples E1 to E5 were drummed, shaved to 1.
In the comparative experiments below denoted by the letter a, one strip each was left in the moist state, i. For assessing the quality of the dried semifinished products, the latter were subjected to retanning to give furniture leather. The resoftening behavior was rated using a scale from 1 to 5, a good rating indicating that a supple, absorptive hide was obtained without further mechanical treatment.
Rating 5 shows irreversible hornification of the tissue. The appearance of the fibers on the flesh side was rated using a scale from 1 to 5. Here too, rating 5 represents inhomogeneous fiber morphology with a high proportion of fiber adhesions. This was followed by acidification to pH 3.
The evaluation of the leather with respect to the quality properties of body, levelness and grain tightness was effected using a rating scale from 1 to 5. The tensile strength was determined according to DIN The results in table 2 show that, in comparative experiments C0b to C0d, the drying led to an extreme quality deterioration in the fiber appearance on the flesh side and to fiber adhesion during resoftening.
No leather end products could be obtained from the dried experimental strips of series C0. A comparison of the a series without drying with the dried experimental strips of series b to d predominantly showed an improvement in the quality features of body, levelness, grain tightness and tensile strength of the retanning end products. Four pickled cattle sides having a split thickness of 3. The tanning liquor contains no clay mineral in comparative example C6, whereas in each case 2.
The pretanned hides were shaved to 1. Thereafter, the basicity was raised to pH 3. The mixture was acidified to pH 3. The washed leathers were sammed, dried and staked and assessed according to the quality features shown in table 3 below. The chromium concentration of the liquor was determined titrimetrically. The liquor exhaustion is based on substances which are used in the further retanning steps, in particular resin tanning agents, fatliquoring agents or dyes, in each case samples being taken after the dyeing and fatliquoring and being visually assessed.
The table shows that, in examples E7 to E9, all leather properties are improved compared with comparative example C6 and moreover the liquor exhaustion is likewise improved. All rights reserved. A SumoBrain Solutions Company. Login Sign up. Search Expert Search Quick Search. Method for producing a leather semi-finished product. Click for automatic bibliography generation.
The process as claimed in claim 1, wherein the chromium-free tanning agent for the pretanning is selected from the group consisting of aldehyde tanning agents, isocyanates, aluminum salts, oxazolidines and tetrakishydroxymethylphosphonium chloride. The process as claimed in claim 1, wherein substances which, owing to their chemical structure, form strong hydrogen bonds with the clay mineral, are added to the clay mineral before or during the use thereof in the pretanning.
The process as claimed in claim 1, wherein the clay mineral is a phyllosilicate. The process as claimed in claim 6, wherein the phyllosilicate is selected from the group consisting of a kaolinite, muscovite, montmorillonite, smectite, saponite, vermiculite, hallosite, bentonite and organically modified variants thereof.
The process as claimed in claim 1, further comprising: moistening the semifinished leather product with an aqueous solution of a tanning assistant which is absorbed into the semifinished leather product by means of physical forces.
The process as claimed in claim 2, wherein the chromium-free tanning agent, which is an aldehyde tanning agent, is glutaraldehyde. The process as claimed in claim 5, wherein the substances are selected from the group consisting of urea or urea derivatives, alcohols, polyols, propylene carbonate, organic amides, urethanes and saccharides or derivatives of saccharides. The process as claimed in claim 12, wherein the saccharides or derivatives of saccharides are selected from the group consisting of nitrocellulose, sulfide cellulose and ethylcellulose.
The process as claimed in claim 7, wherein the bentonite is a hectorite. The process as claimed in claim 9, wherein the drying is carried out on a tenter frame. The process as claimed in claim 9, wherein the physical forces comprise osmosis. The process as claimed in claim 9, wherein the semifinished leather product is moistened with an aqueous solution of a protein hydrolysis product. The process as claimed in claim 10, wherein the tanning assistant is an amphoteric or cationic polymer.
The process as claimed in claim 10, wherein the resoftening comprises spraying the dried semifinished leather product with the treatment. The present invention relates to a process for the production of a semifinished leather product.
For this purpose, semifinished leather products are produced by pretanning, as a rule by the following two, basically different processes: On the one hand, by pretanning with corrosion-containing tanning agents to give the wet blue semifinished product and, on the other hand, by chromium-free pretanning to give the wet white semifinished product. The examples which follow illustrate the invention.
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Tag: semi-finished leather
In the leather industry, the readily perishable raw material, the animal hide, must be converted into a biologically and mechanically stabilized state in order to be storable and transportable. For this purpose, semifinished leather products are produced by pretanning, as a rule by the following two, basically different processes:. On the one hand, by pretanning with corrosion-containing tanning agents to give the wet blue semifinished product and, on the other hand, by chromium-free pretanning to give the wet white semifinished product. Wet blue semifinished products have the disadvantage that they are already chromium-containing, i. Resoftening without a reduction in quality is not possible.
Ethiopia Tannery are one of the largest and most modern tanneries in Ethiopia. The company are fully equipped with modern production lines for cattle, sheep and goat skins up to the finished stage. The company have made a significant contribution to the improvement of hide and skin quality from Ethiopia and have generated much needed foreign currency for the country. Ethiopia Tannery SC, located in Koka near Modjo, about 90km south of Addis Ababa, are a public enterprise established under a technical cooperation agreement signed between the governments of Ethiopia and the former Czechoslovakia on December 11, The factory was initially established as a share company before being transferred as government property during the change of government in
A mosaic of different realities
The leather manufacturing process is divided into three sub-processes: preparatory stages, tanning and crusting. All true leathers will undergo these sub-processes. A further sub-process, surface coating may be added into the sequence. The list of operations that leathers undergo vary with the type of leather. The leather making process is in general restricted to batch processing, but if the surface coating sub-process is added then some continuous processing can be included. Many options for pretreatment of the skin exist. Not all of the options may be performed. Preparatory stages may include: . Tanning is the process that converts the protein of the raw hide or skin into a stable material which will not putrefy and is suitable for a wide variety of end applications.
COMPARATIVE EXAMPLE C0 AND EXAMPLES E1 TO E5
This book is the most complete, accessible, and up-to-date resource for Ethiopian geography, history, politics, economics, society, culture, and education, with coverage from ancient times to the present. Ethiopia is a comprehensive treatment of this ancient country's history coupled with an exploration of the nation today. Arranged by broad topics, the book provides an overview of Ethiopia's physical and human geography, its history, its system of government, and the present economic situation. But the book also presents a picture of contemporary society and culture and of the Ethiopian people. It also discusses art, music, and cinema; class; gender; ethnicity; and education, as well as the language, food, and etiquette of the country.
James E. Austin, Dr. Austin holds the Eliot I. Strategic Management In Developing Countries.
Current Problems of the Leather Industry
Routledge Bolero Ozon. Small firms - including 'microenterprises' and 'small and medium enterprises' SMEs - play a vital economic role in developing countries. They typically provide half of all jobs.
A collection of articles by Samaddar from leading national dailies and journals between and the downfall of the Left in West Bengal, this books analyses the era of the Left rule, its political decisions and its social and economic viability. Samaddar argues that the Left's rule and its own governmental style destroyed the hegemony it had built up through assiduous work of decades. A commentary on contemporary history and an assessment of it, this work helps the reader understand, better, the re-emergence of the Maoist movement in West Bengal, the governmental techniques of the Left and the dynamics of popular politics. He has worked extensively on issues of justice and rights in the context of conflicts in South Asia. His recent political writings The Emergence of the Political Subject and The Nation Form have signalled a new turn in critical postcolonial thinking and have challenged some of the prevailing accounts of the birth of nationalism and the nation state.
Semi Finished Leather
Reporting today on a market's situation, an industrial sector, it is impossible if we don't bear in mind the very complex reality such as that raised by the world economy and its currencies. The devaluation of the dollar versus the euro is producing conflict and benefit zones because, given the current world situation, it affects every region. While the US is working to reduce its huge commercial deficit, stimulating exports and reducing the cost of imports, the current situation, in terms of fiscal and commercial deficit, unemployment, security and other hot matters, is making all world economy operators nervous. How are weaker structures such as the Latin American economies, with huge debts and dependent on the good will of Washington, going to be in good shape? The region of Latin America, regardless of their dependence on the dollar, is not benefiting from the situation despite most of their trade being developed with their northern neighbour. The economy in most of these countries is not a bed of roses. A large part of the US productive capital has moved to the south-east Asian coast, attracted by the advantageous conditions offered by the strong regional governments. As is well known, due to the growth of that region, highly superior to Latin America's, the companies found their ideal spot for production at very cheap labour costs.
Chrome tanned leather shipments were up Juft leather is a term which is particularly relevant to the Russian leather industry and is described as thick, heavily fatliquored, hard wearing low cost leather. The lowest grades of wet-blue are processed into leather suitable for work boots.
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- Быть может, придется ждать, пока Дэвид не найдет копию Танкадо.
Я люблю тебя, - шептал коммандер. - Я любил тебя. У нее свело желудок. - Останься со. В ее сознании замелькали страшные образы: светло-зеленые глаза Дэвида, закрывающиеся в последний раз; тело Грега Хейла, его сочащаяся кровь на ковре; обгорелый труп Фила Чатрукьяна на лопастях генератора.
Стоящая перед ним задача была крайне деликатна и требовала массу времени - вписать скрытый черный ход в сложный алгоритм и добавить невидимый ключ в Интернете. Тайна имела первостепенное значение. Любое подозрение об изменении Цифровой крепости могло разрушить весь замысел коммандера. Только сейчас она поняла, почему он настаивал на том, чтобы ТРАНСТЕКСТ продолжал работать. Если Цифровой крепости суждено стать любимой игрушкой АНБ, Стратмор хотел убедиться, что взломать ее невозможно.
- Ты по-прежнему хочешь уйти. Сьюзан посмотрела на .
Если ты хочешь назначить мне свидание, я освобожусь. Если же нет, то позвони электрикам. - Джабба, дело очень серьезное.