DE1635500A1 - Process for the production of synthetic shoe upper leather - Google Patents

Description

Carl Freudenberg Weinheim / Bergstr., December 21, 1 '

Process for the production of synthetic shoe upper leather

In recent years, new synthetic leathers have been offered to replace natural leather. The PVC synthetic leatherette SKAI and HELIA are well known. To produce them, a thin layer of a PVC paste is spread on a textile carrier material (woven, knitted or non-woven fabric) - directly or in one of the numerous so-called reverse processes Z ₀ B _{0 according to US Pat} allowed to gel at 160 ° C.

The resulting products are leather-like after printing Pattern on the PVC surface of natural leather externally no longer distinguishable and are often made into suitcases or handbags. Because they are completely impermeable to water and air are, in this respect, they are often preferred to natural leather »

On the other hand, PVC synthetic leatherette is suitable as a shoe upper leather but precisely because of their complete impermeability to water not.

However, other methods have been developed for the production of synthetic shoe upper leathers. They essentially consist of that a fleece made of NYLON or polyester fibers is needled, whereupon this needle fleece, which is sometimes also synthetic Contains shrink fibers, impregnated with a binder. as Binding agents, latices or Vulkollan solutions can be used. Corresponding methods are described in U.S. Patents 3,067 and 3,067,483 and 2,723,935.

These synthetic shoe upper leathers, which are available under the trade names CORPAM, CLARINO, XYLEE, SKAILEN, are permeable to water vapor, however, their water storage capacity leaves a lot to be desired ο natural leather can hold up to 35 # of its own weight, for example Absorb water without the wearer having the feeling of walking in a damp shoe. In the case of the above synthetic In shoe upper leathers, this barrel storage capacity is about 10 times less If your foot sweats easily in summer, then it's all in one Synthetic upper leather shoe quickly absorbs water Reached from $ 1 - $ 4, and the wearer has it even in dry weather constant uncomfortable feeling of walking in damp shoes.

One has therefore already proposed another method for the production of synthetic upper leather, which products with better

Water balance supplies. In this process, the animal skin (often waste) in collagen fibers from o, oo1 "to 4 mm Length ο These fibers are slurried in water. Then pour this collagen fiber dispersion on a mostly lightly pre-needled synthetic fleece. The collagen fibers should be in the Distribute the round skeleton of the fiber fleece while the water drips off “The collagen fibers wrap around the synthetic fibers of the basic skeleton so intimately that a solidification of the fiber sheet, which now consists of plastic and collagen fibers is achieved.

Since the collagen fibers still contain a lot of water, the latter must be used still to be removed. This is done by immersing the resulting fiber sheet in acetone. The latter is suppressed the water from the collagen fibers. The acetone is then also removed from the fibrous sheetlike structure at a higher temperature The fibrous sheet is then dipped into a conventional, diluted chrome tanning broth to remove the collagen fibers in the fibrous sheet to tan. It is then washed and, if necessary, still pressed. in the Swiss patent specification 412 325.

Those made from synthetic fibers (nylon, polyester fibers) and from, through mechanical Splitting of skins formed, collagen fibers existing artificial leather have a better water balance than the

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Shoe upper leather consisting only of synthetic fibers, such as GOEi ¹ AM; their mechanical strength, however, often leaves something to be desired. In addition, because of the strong swelling of the collagen, it is difficult to handle aqueous collagen slurries with a high dry matter content and even to penetrate the fleece evenly The synthetic shoe upper leathers described below combine the strength of CORFAM leathers with the good water balance of synthetic leathers containing collagen fibers.

To represent the synthetic shoe upper leather according to the invention, a "fleece" consisting entirely of plastic fibers is first prepared with the help of a card and a cross-layer by laying several piles on top of one another. (Details of this known device can be found on page 69 of the book "Textile _{Composites" by Dr e} R _e Krcma, VEB Fachbuchv.erlag Leipzig, 1963, can be taken »)

During the laying of the individual coming from the cross-layer Pile for a fleece is sprinkled dry, ground (preferably already tanned) collagen powder on the individual Flore »In this way, the largely dehydrated collagen powder is evenly distributed in the fleece. This uniform distribution is particularly easy to reach in the present case because the collagen - not as before in fibers, but is introduced in powder form.

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Then the synthetic fleece is needled with the introduced collagen powder and then with a latex dispersion or Acronal dispersion (Acronal is a trade name for polyacrylate esters) impregnated and dried at temperatures at which the binder vulcanizes or hardens. Even binders dissolved in organic solvents such as in particular Vulkollan (registered trademark of Bayer, Leverkusen) are ideal.

The resulting products have excellent tear and abrasion resistance. At the same time their water balance becomes much better than that of all known synthetic breathable shoe upper leathers.

The dry, ie largely dehydrated, collagen powder required according to the invention can be produced, for example, from skin waste using known comminuting machines and drying systems. It can be untanned or tanned by known methods and contain ο - 2o i ° moisture. If you use untanned collagen powder in the manufacture of the fleece, in order to prevent the protein from rotting, you have to tan, namely by the fact that the plastic fleece together with the untanned collagen powder before or after impregnation with a binding agent exposed to the action of tanning agents, e.g. veget. Exposing tannins, chrome broths, formaldehyde or dialdehyde.

The production of the fleece with card and cross-layer "at the same Incorporation of collagen powder has already been mentioned. However, the fleece can also be made with the help of a so-called rando weaver (Details can be found in the book NONWOVEN FABRICS by F.M. Buresh, Reinhold Publishing Corp., New York, 1962, p. 14 to 18).

In this case, the collagen powder is whirled up in the air together with the fibers and the whole thing on a suction drum collected. In this case, too, an even distribution of all components is achieved.

The amount of collagen powder introduced into the synthetic fleece can be obtained within wide limits e.g. Io - 5o $ on the weight of the finished product.

The base fleece used according to the invention (into which dry collagen powder is sprinkled) should consist entirely or at least largely of synthetic fibers, in particular nylon, perlon, polypropylene or polyester fibers of medium titre (1 to 5 denier). If large amounts of cotton wool or cotton are used, the mechanical properties of the synthetic upper leather drop sharply ₀ On the other hand, a small addition, e.g. up to 5 # wool, is beneficial because the wool shrinks considerably when the impregnated product dries, creating a denser structure that is more leather-like as a bulky fleece mixture.

Since today almost all synthetic fibers can also be produced in a strongly shrinking variation, it is advisable to add about 3o "to 60 $> _ of these shrink fibers to the starting fleece, then sprinkle the collagen powder and then needle the whole thing and finally a heat treatment in a hot air chamber, steam chamber, etc. The initial fleece shrinks considerably. Before the heat treatment, the collagen must have been tanned. Subsequently, it is impregnated in such a way that 10 to 60 10 binder based on the dry weight of the binder, and the total weight (i.e. fiber - Collagen binding agent).

The products according to the invention are then treated with a customary porous cover layer made of PVC, polyurethane, synthetic rubber such as neoprene, copolymers made of butadiene-u-styrene, etc. Mistake. These cover layers can for their part again according to known ones Process are printed and / or embossed in order to increase the leather-like appearance.

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Claims (7)

1. Process for the production of synthetic leather based on fiber fleece, suitable for the shoe and upholstery industry with a water balance that is largely that of natural leather equals, characterized in that in the production of the initial fleece from non-swellable fibers dry collagen powder sourced in amounts from Io to $ 50 adds to the weight of the end product. 2. The method according to claim 1, characterized in that the Fleece containing collagen powder is additionally needled. 3. The method according to claim 1 or 2, characterized in that the sheet is then impregnated with a binder will. 4. The method according to claim 1 to 3, characterized in that the collagen powder in the untanned state in the fleece incorporated and treated there with known tanning agents. 5. The method according to claim 1 to 3, characterized in that the collagen powder in the pre-tanned state in the fleece incorporated " 6. The method according to claim 1 to 5, characterized in that the fabric is provided with a customary top layer, 7. The products produced according to claims 1-6. 209821/0737