DE1469550A1 - Synthetic leathers and process for their manufacture - Google Patents

Description

Λ4 TEAfTA AfMSÄi. TE

PATENTANWALT MÖLLER-BÖRNER PATENTANWALT DIPL.-ING. WEY BERLIN-DAHLEM - PODBIELSKIA LLEE 68 MUNICH 22 WIDENMAYERSTRASSE 49 TELEPHONE 762907 - TELEGRAMS: | HUUPINUUA PiLEPU ¹ IH 125585 TELEGRAMS: PROPINDUS

16 676 D _n Expl ^Ber11

Expl.

α, November 16, 1964

Kurashiki Bayon Company Limited, No ₀ I62I, Sakazu, Kurashiki City (Japan)

S ynthetic leathers and processes for their

Manufacturing

The invention relates to supple, air- and water-permeable nonwovens with high strength and a process for their production so-called "synthetic leather ¹¹ , as well as a process for their production,

The new types of "synthetic leathers" have in recent years Attracted worldwide attention to sioh for years. Auoh in Japan, which is not excluded from this development, this led to a certain boom «

For a long time the manufacture of synthetic products * sen, which have the same structure as natural leather, was a dream «-» idea of the experts. First is the so-called "regenerated leather" has been manufactured using a process

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TELEPHONE: 0184OS7

In which pieces of natural leather are crushed in two basic stages and these crushed pieces are then dissolved, whereby the focus was more on the economic use of natural leather waste than on the fact that the synthetic product has the same composition as natural leather. Furthermore, the Versuoh has been undertaken, a product with natural leather characteristic of \, create by such natural leather has given you regenerated leather for Sohein the same scent. These experiments served to investigate the "regenerated leather ¹ · more closely, and in certain areas natural leather has been replaced by" regenerated leather. "There are a number of processes which reveal the prospect that" regenerated leather "also applies However, these efforts did not achieve the desired ideal because it was difficult to produce protein bodies, which are the main constituent of natural leather, and because the leathers produced have some unfavorable properties it cannot be assumed that the desired goal can be achieved in the near future and that "regenerated leather" will be produced on an industrial scale.

In this situation, artificial leather, the so-called "imitation leather", has hitherto been regarded as a substitute for natural leather. Synthetic leather was made by adding fabric initially with nitrocellulose and then with vinyl chloride or rubber

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alternating coatings were coated. The artificial leather he " does the natural leather hold due to the composition of the cover? - similar structure and by pressing in scars the natural " leather-like appearance. The physical strength of the Artificial leather, however, depends solely on the thread used Ah.

However, the developments in the plastics industry have in recently led to a group of worked fabrice, the so-called "synthetic leathers", which exceed the level of "imitation leather" by different types of plastics have been produced whose physical strength and chemical resistance », are not inferior to that of natural leather, for which it has been suggested to use non-woven fabrics instead of fabrics To use textile industry products and a To use a method for obtaining microporous sponges or a wet method, in which, in contrast to the

en
known drying process, a film is formed in a liquid medium. The so-called "synthetic leather" is competitive with natural leather in certain areas and is used in the manufacture of certain products on a larger scale than the latter, since it exceeds natural leather in some properties and is cheaper than this. However, it would appear that the related industries both in Japan and abroad match the one currently on the market

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Synthetic leathers are not fully satisfied because they have an »unsightly external appearance and inadequate properties has «For the sole production in particular, the synthetic leather is so much worse than natural leather that on Intensive investigations and developments in this area with regard to suitable materials and components in are highly desirable and necessary «

In Japan, shoe manufacturers primarily demand a synthetic leather that looks and feels like natural _{leather $} like other synthetic leather-processing industries want it, while processability and other properties are only of secondary importance _# Recently, however, it is becoming more and more important a synthetic leather is desired that has not so much the appearance but rather the qualities of natural leather and surpasses them as much as possible.

The inadequacies of natural leather pose major problems, Seeing synthetic leather in a different light «To make a correct assessment of synthetic leather to come, it is therefore necessary to consider the advantages and disadvantages » to clearly highlight parts of natural leather «In short, the new synthetic leathers should have the desired« have the valuable properties of natural leather without, however, having its disadvantages «

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Natural leather has the following structure: the main part of leather is the Dennis, which essentially determines his qualities. The epidermis determines the external appearance, and the hypodermis, the so-called hypodermal adipose tissue determines the. Type of back surface of the finished leather, if the skin at this point is peeled off «The dermis is made up made of collagen, and the properties of leather due to the collagen are as follows:

1 «The collagen fibers of the dermis are at all angles with connected to the surface of the dermis and thus form a solid network,

2. The collagen fibers also keep their supple then « speed when the moisture is completely removed from them and rarely break when they are in any Direction to be bent »

3 "The collagen adjacent to the papillary surface" fibers extend parallel to the surface of the leather and are stronger than the inner cross-linked sole «Ausser- there are elastic fibers inside that protect the leather surface from breaking and collapse give a pitted appearance »

4 «Every collagen molecule has a weakly linear structure, especially one (herioa $ configuration, and some

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Molecules are one after the other to one million, one Fibril, a visual fiber and the bottom of a three-dimensional fiber connected »

The usefulness of the leather is not limited to its individual Properties attributed, but rather to the fact that these individual properties are so outstandingly interrelated combined are «This is a remarkable characteristic of leather, as it has not been found in other materials · Leather also has it because it is a natural product is, some special properties that are not mimicked * On the other hand, leather has some characteristics see defects, but they are a general characteristic of natural products. That is why it is for the professional world of It is essential to know exactly the advantages and disadvantages of leather, and the explanations in the following paragraphs can be described as general knowledge. Thereby the advantages of the leather with the suitability and workability it is associated with shoe making, while the shortcomings reveal problems that arise in describing the synthetic leather must be specially noted *

Natural leather has the following advantages:

1 «Because of its grained surface, leather has a uniform appearance beautiful appearance «The term" leathery "is commonly used, and leather trim goes well with both Japanese as well as European clothing,

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2, leather fiat high, balanced mechanical strength! ^1st Breakage and shear strength of leather are greater than in other materials that are similar to leather in other properties, and no differences in strength can be determined in the longitudinal and transverse directions as with other materials.

3, the leather has a gleiohförmige Spannung8 "strain" curve, d, h, that leather has a greater modulus than other _A for the same purposes, the materials used, and the difference of tensile strength and elongation in the dry and wet state is not so large as with other materials in view of the great differences in the other properties «

4, The leather is supple, easy to shape and has a low specific weight »This is why leather is highly deformable and very easy to process,

5 · Leather absorbs moisture very well and is moisture and air permeable. This property, combined with others, is extremely essential and desirable in the case of raw materials for products currently in use,! Especially in the case of high humidity, such as is found in Japan * '

6 _β Leather has temperature-retaining and heat-insulating properties. This is evident from its structure, so that it can be used excellently as a heat-insulating material for use in winter *

7 «Leather can be made into products with any desired clip« surface can be deformed, that is why leather has a excellent workability, and is known to be the harmonious interaction of impact resilience and suppleness a characteristic leather property «

8. Leather is easy to cut «Although the fabric is solid and layers with different densities occur " the fact that the leather has this property can be attributed to the composition of the various components.

9. Leather can be dyed with ease «This is why the grained surface is firm and uniform and the leather is suitable for use as ornaments and clothing« -.- ■ ^; - - ■ '* ■■ - ■ ■ · · -''■■ · "· .-- ■ ^-: - ■>^{·:; ··':} · - ^{- 1}

The disadvantages include the following:

1. Depending on the breed of animal and the area in which the animals live / has - the leather has different properties «

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and they are even with the same breed of animals Properties of the leather depending on gender, age, lining, season etc. «different, and in a single piece of leather the properties can give way,

2, leather is different in shape and thickness from piece to piece, so it has to be processed by hand and is difficult to handle by machine ₀

3 _# As described above, the leather is limited in size and the parts with the same properties are small, so that it is difficult to cut a piece of any shape from the leather piece, which of course increases the cost,

4, For this reason, leather is not cheap, and besides it is not manufactured industrially as the main product, but is a by-product of the Meat production, so that the amount of leather available depends on the weather, the meat demand and the Price depends "

5 · To form leather through the skin both a long time is required as well as a complicated Tanning · * _t process and the production and quality control in

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the tanning industry are associated with difficulties because the basic research on raw hide protein body and the punctures and effects when tanning are not fully completed »

6 »It is difficult to protect leather against decay and vermin-» to stabilize infestation at high humidity like in Japan, because it is a natural product and essentially consists of protein bodies.

These are the main defects of the natural product leather * It is therefore a task for the manufacturers of synthetic leathers to see these disadvantages identified in natural leathers off, to improve the advantages of natural leather without deteriorating the other properties and on this way to improve the combined properties.

It is an object of the invention to provide synthetic leather which has the benefits of natural leather and both Defects of the latter are completely eliminated, as well as a Process for its manufacture.

In short, the synthetic leathers according to the invention can be obtained daduroh that one layer or fibrous Mat is formed from intermingled fibers, the intermingled fibers of at least two High molecular substances exist that the Sohioht with the

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Solution of one or more high molecular weight substances is soaked, that the impregnating substance is precipitated by a dry or wet process and that ultimately at least one high molecular substance that is a component of the mixed-spun fibers by treating the layer in a solvent for at least one of the high molecular weight components forming the fibers Substances is extracted and removed,

The intermingled fibers can be processed by a wet, dry or Melt spinning processes are produced from a mixture of two or more high molecular weight substances, whereby the Sohmelzeltspinnverfahren the most advantageous is »The threads are stretched two-fold after spinning.

Polyolefins such as polyethylene and polypropylene, atactic and isotactic, for example, can be used as high molecular weight substances Polystyrenes, alkyl- or halogen-substituted polystyrenes, polyamides such as 6-nylon and 66-nylon, polyesters such as polyethylene terephthalate, Polymethacrylates such as polymethyl methaorylate, polyvinyl ester such as polyvinyl acetate and polyvinyl butylate, polyvinyl alcohol and its derivatives, polyvinyl halides such as polyvinyl chloride, polyacrylonitrile, polyvinylidene halides such as polyvinylidene chloride, Cocondensates or copolymers from various low molecular weight condensed or polymerized substances and high molecular weight grafts used in the graft polymerization of various low molecular weight polymerizable substances with different homopolymers or their cocondensates

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or copolymers are obtained «of course» the selected two or more high molecular weight substances mixed spinnable. The expression "spun mixed" bar "means that necessarily when spinning the fibrous The shape has to be retained, but not that the resulting thread have a uniform internal structure must «It is two-fold if the mixing ratio for these mixed-spun fibers is set in such a way that that at least $ 20 of the one high molecular weight substance compared to the other. The spun from the mixed High molecular substance to be removed and extracted is swollen or in a solvent dissolved, which is a solution of the impregnating layer high molecular weight substance. This Veise is through the pressing action during the precipitation stage is sufficient solid synthetic leather achievable.

The resulting mixed-spun fibers are then formed into a soft or fibrous mat by a wet or dry process. This is very coarse, and if an end product with high strength is to be produced, this sole or fibrous mat must be compacted in a suitable manner. This process is preferably carried out in the following manner ι The mix-spun filaments are cut into staple fibers, which are processed with the aid of a suitable device to an arbitrary layer. The arbitrary sole is then duroh

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a needle prick condensed and three-dimensionalized * When the compression is sufficient, pressure is applied to further compression ^ 'This involves heating the layer expedient. Compression can also be achieved by shrinking of the fibers. To achieve an end product with high strength, the nonwoven can be stretched while preventing shrinkage «

An essential feature of the invention is the production of such three-dimensional non-woven products « For the production of a good synthetic leather it is a basic requirement that the layer is pliable and pliable «To be so pliable and supple To produce a layer, it is twofold to use fibers with a fineness of less than 1 denier, preferably less as 0.5 denier "to use" However, it is difficult to make any material, such fine ones Fibers sent through an Eadiervorriohtung (card silver) and to obtain a non-woven product from it with the help of a needle punch, because only the fine fibers are very difficult to spin "

In contrast, according to the invention, well-spinnable fibers with a thickness of 1.5 to 3.0 denier can be processed into a sole will be «a dioker's thread with a thickness of swisohen 1,5 and 3.0 denier is much easier to spin than fine Threads with a diameter of 0.5 denier and less «one out

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The layer made from 1.5 to 3.0 denier thick fibers is generally not flexible. traction process, however, at least one high molecular weight substance is removed from the paser, which makes it possible becomes a layer having the same flexibility as in the case of very fine fibers of 0.5 denier or less To get thickness,

According to the invention, mixed-spun fibers consisting of at least two components are used as a shaped fibrous mat, wherein in the subsequent stage one component is soluble and the other is insoluble. This has another advantage. If a layer of fibers is to be made, that only consist of a single high-molecular substance, which are difficult to spin, so that only so difficult a Layer can be produced, another can be added to the named high molecular weight substance * The mixture can then be processed into well-mixed spinnable threads, from which then, after they have been turned into fibers have been cut up, a layer can be produced. For example, 6-nylon alone Threads are difficult to spinn because of their Young's modulus and the unfavorable dry-wet ratio of Young's modulus. As mentioned above, 6 nylon threads with a fineness of 0.5 denier can only be sphwered spin. In contrast, have mixed spun threads

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from 6-nylon and polystyrene a better Young module and a better dry-wet ratio of the Young's modulus, such as Table 1 can be taken from *

Table 1

Mix Polystyrene 0 10 20th 10 40 50 60 relationship 6 nylon 100 90 80 70 60 50 40 Young Dry, (g / d) 18th 21 24 30th 33 36 40 module Wet (g / d) 10 21 23 26th 30th 33 38

As can be seen from this table, the 6-nylon and polystyrene mixed-spun fiber have an improved Young's modulus and a significantly better one Young's modulus dry-to-wet ratio. By using a mixed spun fiber with a fineness of 1.5 to 3 »0 denier instead of one with a Fineness of about 0.5 denier, therefore, makes it possible to easily produce a three-dimensional nonwoven layer with the usual equipment and brewing ob-

iy. can

borrowed process conditions are used / because a There is a remarkable improvement in spinnability and better separability from the carding machine *

The layer produced in this way is impregnated with a solution of a high molecular weight substance

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high molecular weight substance can be used 1) one or more high molecular weight substances with rubbery Ela— sticity and 2) mixtures of one or more high molecular weight substances with rubber-like elasticity one or more high molecular weight substances without rubber-like elasticity, the solution does not necessarily have to be a common solution, but it can also be an emulsion be used if this layer is used in— can be impregnated. The solution can contain salts, dyes, pigments, fillers, various surface- » active agents and other additives are mixed in "

These substances must be insoluble in the solvent that for the extraction of the extractable high molecular weight Substance from the mixed spun fiber is used · Examples are elastic high molecular weight Polyurethanes, acrylates, synthetic rubbers ^ chlorinated Polyethylene and polyolefin derivatives, ia internally softened high-molecular substances and other high-molecular substances Elastomers with rubbery elasticity.

As a high molecular substance without rubbery elasticity various polymerized or condensed high molecular weight such as polyvinyl chloride, polyacrylonitrile, poly styrene, polyvinyl alcohol, or its acetalization products, polyvinyl acetate, polyamides, modified polyamides, polypropylene, polyethylene, polyurethane, polyureas, polyesters, polycarbonates or their co-condensed

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or copolymerized compounds as well as high molecular weight Graft polymers are used »

After impregnating the layer with the high molecular weight Substance is the impregnating substance through a wet » or dry process precipitated. It is advantageous if the impregnated Sohioht before, during or after Precipitation process is pressed, possibly hot.

The layer is then treated with a solvent, with at least one of the high molecular weight compounds, which is a component of the mixed spun fibers forming the sole, is extracted · It is two « massive, part of the impregnated high molecular weight substances that are extractable and removable, and one Proportion of a coating film applied to the pitted surface in the manner described below will be removed before, during or after the extraction stage »

According to the invention for the extraction of at least a high molecular weight substance used to form the intermingled spun fibers must be used for at least one high molecular weight substance (soluble component) be a solvent, while for the remaining (insoluble component) high molecular weight substance of the blends spun fiber is a non-solvent. Even though

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the suitable solvent of the nature of the starting materials for the mixed spun fibers for the manufacture development of an artificial leather according to the invention depends, to water, organic solvents such as aromatic Verbin ™ fertilize, cyclic ethers, aliphatic hydrocarbons, ketones, cyclic ketones u "like _a, various salt solutions such as methanolic solutions of calcium chloride, titanium, tetrachloride lithium chloride etc. and mixtures thereof are used "

The synthetic leather obtained in this manner according to the invention is a fibrous layer such as natural leather, a Vo11 can has η fibrous structure, and it has the same external appearance, the texture, feel and other properties like natural leather, "The synthetic leather according to the Invention meets all requirements as set out at the beginning *

The fact that the synthetic leather according to the He FIN "dung ait natural leather is comparable to or even exceed this in all points due to the continuous structure whose properties are described in more detail below"

One of the properties of the synthetic leather according to the invention is that the fiber which forms the leather has numerous micropores and that during the extraction of at least one high molecular weight substance which forms the fiber

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a pitted surface is achieved. Therefore, the synthetic leather of the invention is very flexible and in
its structure is similar to that of natural leather.

This has the following causes: The fiber itself is more flexible due to the micropores formed in it, and those on the
Soluble component present on the surface of the fiber
has been extracted, whereby a number of cavities are formed between the impregnated fabrics and whereby the high molecular weight substances with rubber-like elasticity are separated in the fiber and thereby movable relative to one another.
The micropores and cavities bring about a considerable improvement in the air permeability, the moisture permeability and the air-retaining properties and create a leather-like structure.

A large number of micropores in the moldings after
of the invention results not only from the cavities formed between the fibers which form the shaped body, but also from the spaces between the fibers
itself. The porosity of the fiber depends on the proportions of the two or more high molecular weight substances present in the starting fiber. This is explained in more detail using the following example.

By mixing 6 — nylon and a polystyrene in different Mixing ratios produced Flooken by

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a nozzle nit 100 Löohern of 0.2 mm diameter to form threads with different mixing ratio ge "presses, which at 175 ° G to 300%, and then at 200 ⁰ C to 50 i" are stretched (total draw ratio 500%) "The stretched filaments are extracted from them with benzene at 65.degree. C. to remove the poly styrene. The porous fibers have the following properties:

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OO O co € 0

to

Mixing ratio
of polystyrene (%) Fineness (d) 5 3.0 10 20th 30th 40 50 60 80 Before the
extraction
of the poly
styrene Firmness (g / 31 7.5 3.0 3.Q 3.0 3.1 3.0 3.0 By E
fibrous
reach Uach the
Extraction
of the poly
styrene .Extensibility {%) 21 7.6 \ 7.2 δ. 5 "77Q-- Ό "" B72 " ictraction ke:
ar condition
3 ar A / "Q Fineness (d) 2.9 23 19th 23 24 23 22nd Strength (g / d) 7.2 2.9 2.9 2.4 1.9 1.5 1.2 Extensibility (%) 23 7.5 7.0 6.7 6.8 6.5 6.9 Porosity {%) 3 24 25th 21 23 25th 21 1.01 4th 6th 20th 38 49 60 0.99 1.00 0.98 0.99 0.97 0.98

IO

ro I

A: Cross-sectional area of the fiber after the extraction of the polystyrene

B: cross-sectional area of the fiber before the extraction of the polystyrene

(In the table above, the porosity value is through Divide the denier of the fiber after the extraction of the polystyrene by the denier of the paser that just consists of insoluble component with the same cross-sectional area.)

As can be seen from the table above, the fiber of which the molded product according to the invention is made has a porosity of up to about 70 %.

Another feature of the synthetic leather of the invention is its considerable flexibility.

In order to obtain a flexible mat, it is generally desirable to use a low denier fiber, because a mat of higher denier fibers is too stiff. However, fine fibers are difficult to spin * On the other hand, fibers according to the invention with relatively high denier with good spinnability for processing can be used to form a layer, whereby a synthetic leather can be obtained which is just as flexible as if very fine fibers had been used, because the Young's modulus was reduced by the extraction and at least a high molecular substance constituting the fiber has been removed. By roughening eggs on the back surface of the synthetic leather obtained, the fibers are attached to the roughened * Provides very low denier fibrinates, making the synthetic leather an excellent leather-like appearance Gives structure.

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The process of making synthetic leathers according to the invention will be explained in more detail below with the aid of an example which, however, is in no way restrictive of the invention explained.

Of 40 parts of 6-nylon and 60 parts of polystyrene existing mixed flakes are pressed with a screw press through a spinneret with 300 holes of 0.2 mm diameter at a spinning temperature of 300 ⁰ C in a drawing zone, by blowing air at 120 ⁰ C has cooled down. The resulting threads are wound up at a speed of 600 m / min. The threads mixed in this way are crimped at 24 / inch and cut into fibers 3 cm in length, from which a three-dimensional layer of 330 g / m is formed with the aid of a suitable device (random webber) and a needle prick. The layer is lightly pressed with hot rollers at 100 C. Then it is immersed in a 13% dimethylformamide solution of an elastic high molecular weight polyurethane type, which has been prepared by reacting adipic acid polyester and ethylene glycol and diphenylmethane diisocyanate and glycol, precipitating in water and drying, and to extract the remaining solvent and the polystyrene of the fiber treated with toluene. The flexibility and structure of the layer treated in this way are considerably improved compared to before the extraction, so that the layer has the basic properties of leather, such as air-retaining properties,

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Air and moisture permeability, etc. This has the following reasons: The fiber itself is through enclosed, » coherent and arbitrary micropores, which have been created by extraction of the polystyrene, are more flexible become; polystyrene has been partially removed from the surfaces of the fibers and between the impregnated High molecular weight substance and the fibers have formed cavities, so that the fibers can move easily against each other became ; Air and moisture permeability and air retention are due to the presence of the uniform cavities have been significantly increased. That on Synthetic leather obtained in this way according to the invention has appearance, texture and other properties like natural leather. In other words, the synthetic leather according to the invention is composed of fiber layers, which are perfect have the same fiber structure as natural leather.

A grained surface, which is a characteristic of natural leather, can be produced in synthetic leathers, by applying a film or the like to the surface thereof, which is carried out according to the invention in the following manner can be. On the surface of the synthetic leather produced in the manner described above an appropriate amount of a solution of a high molecular weight Applied substance that is precipitated by a dry or wet process. Precipitation is preferred carried out in a wet process, but can also partly in the dry process and finally mainly in the wet process be made.

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The following are suitable as hoclunolar cover materials: 1) One or more high molecular weight substances with rubbery elasticity and

2; Mixtures of one or more high molecular weight substances with rubbery elasticity and one or more high molecular substances without rubbery elasticity. The terms "high molecular weight Substance with rubber-like elasticity "and" high molecular weight substance without rubber-like elasticity " have the same meaning as already described above. The term "solution" is a High molecular substance means not only "real solution" but also "emulsion".

The solution can contain salts, dyes, pigments, various surfactants and other additives are mixed in.

For the spontaneous removal and extraction of part and part of the impregnating high molecular substance the high molecular substance from the pitted surface with removal of at least one high molecular substance from the fiber it is useful if these three high molecular weight substances are of the same type. However, this is not the case indispensable.

The removal of part of the impregnating high molecular substance and part of the pitted Coating applied high molecular weight substance under

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simultaneous removal of a high molecular weight substance from the paser gives the synthetic leather improved Properties such as sufficient flexibility and air and moisture permeability. According to the invention, the following can also be used to achieve a pitted surface Be made: At any stage in the manufacture of the synthetic leather, an appropriate amount of a high molecular substance on the surface of the layer applied and subsequently precipitated by a dry or wet process; The following are the individual options described in more detail:

1. A layer of mixed-spun fibers is impregnated with the solution of a high molecular substance, after which the impregnating substance is partially or completely precipitated by a wet or dry process will. After that, it becomes a solution of a high molecular substance applied by coating or spraying to form a pitted surface, which is caused by a wet or Dry process is precipitated. Then we-d mixed the layer in a solvent for at least one of the spun fiber-forming high molecular substance is dipped to remove it from the fiber, and finally washed and dried.

2. A layer of mixed-spun fibers is combined with the Solution of a high molecular weight substance is impregnated, and then by coating or spraying the

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Solution of a high molecular weight substance applied so that a pitted surface is formed. Then both high molecular substances are made by a dry or wet process failed. At least one high-molecular substance is extracted from the mixed-spun fiber and the layer thus treated is washed and dried.

3. A layer of mixed-spun fibers is soaked in a solution of a high molecular weight substance that is precipitated by a wet process. The layer is then washed and dried, followed by coating or spraying a solution of a high molecular substance is applied to a pitted surface achieve. Then at least one high molecular weight substance of the fiber is extracted from it and so treated layer washed and dried.

Even if the high molecular weight substance is relatively thick The resulting synthetic leather has a layer that is sprayed or applied to form a grained surface sufficient air and moisture permeability. These are important properties of leather because part of the applied high molecular weight substance is removed by extraction in a subsequent process stage. the Removal of part of the high molecular weight substance causes tiny indentations, causing the synthetic leather to look after the invention is extremely leather-like in its appearance.

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The pitted surface can also be formed by forming a Layer of mixed spun fibers are made »which are made from a genic of a high molecular weight substance with rubber-like elasticity and a high molecular substance without rubber-like elasticity exist, this layer is layered on a synthetic leather produced in the manner already described according to the invention. Afterward the high molecular weight substance becomes completely or almost completely from this layered layer solved, whereby it is firmly connected to the synthetic leather.

In the production of the synthetic leather according to the invention, a step can be added if desired, in which the non-extractable high-molecular substances of the mixed-spun fibers are partially dissolved, so as to to glue the fibers together.

In addition, the mixed spun raw fibers can be used for the synthetic leather according to the invention in a mixture with other fibers, for example monopolymers or natural fibers, be used. In the production of synthetic leather according to the invention, a fabric made of synthetic

exist

fibers made of monopolymers and / or natural fibers, as Core layer or substrate can be used.

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According to the invention, the two stages "precipitation" and "Extraction" can be carried out at the same time.

The invention is explained in more detail below with the aid of examples which, however, do not imply any restriction.

example 1

Stretched and crimped, mixed-spun nylon-polystyrene fibers (40:60) of 2 denier thickness are cut into staple fibers of 5.0 cm in length, which are then punched by a suitable device (random webbing) and needle punching to form a non-woven mat of 220 g / m is processed. This non-woven mat was immersed in an impregnation solution, which was obtained by adding 0.4 % cellulose octadecyl urethane as a plasticizer to an 8 % diethylformamide solution of elastomeric polyurethane, which was obtained by reacting polyethylene propylene adipate (molecular weight 1500, molar ratio of ethylene glycol units to propylene glycol units 0.7: 0.3), ρ, ρ'-diphenylmethane isocyanate and ethylene glycol in a molar ratio of 1: 2.5: 5 was obtained. The mat was then squeezed out from both sides with wipers, the amount of solution taken up by the mat being adjusted to approximately eight times the mat weight. A 10% strength solution of the above-mentioned polyurethane in dimethylformamide was applied to the surface of the mat impregnated in this way in an amount which was four times the weight of the mat. The mat

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then immersed for 15 minutes in a 30% aqueous solution of dimethylformamide of 30 ⁰ C and expressed, wherein the impregnation and coating substances precipitated, then washed briefly with water, after having passed through hot pressing rollers. Finally, at least 95 % of the polystyrene present in the mixed-spun nylon-polystyrene fiber was extracted with toluene at 70 ° C and removed.

The layer thus obtained was due to the low adhesion of the nylon fibers with the polyurethane elastomer and the presence of micropores were formed by ÄK extraction of the polystyrene in the nylon fibers, extremely flexible and had a soft texture. The grained surface of the layer was extremely tough, fine-grained and flexible due to the presence of the fibers and had the same structure as natural leather, in particular one that is suitable for clothing. As the following table shows, the layer had the same properties as sheepskin.

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U69550

Synethetic
Leather after the
invention Sheepskin
(Sweden) Sheepskin 3weight (g / m) 213 269 218 Thickness (mm) 0.68 0.53 0.64 Apparent specifi
shear weight (g / cnw) 0.45 0.51 0.34 Tensile strength (kg / 3 cm) 22.4 21 j4 Tensile strength (kg / mm) (along
χ across)
1 ^ 10 X 1 _χ 09 . __li.35_ _ O _x 30 Extensibility (%) 75.0 39.5 33; 9 Shear strength (kg) 3.0 1.4 2.0 Surface fatigue (time) 150 12th 219 Friction resistance (time) 1,000 -
2,000 500 -
1,000 1,000 -
2,000 Rigidity (mm) 45 52 27 Water content (%) 15th 14th 14th degree of water resistance (cm) 155 143 225 air permeability (see.) 41 19th 48 moisture permeability
[g / m ² / day) 8490 8220 7310

Example 2

A non-woven mat with a weight of 330 g / m, from the mixed spun nylon fibers polystyrene was (40 * 60) was immersed in an impregnating liquid, which had been prepared by adding a 2.5% solution of each monostearate and 3 % Carbon black and titanium dioxide to a 13 % ± gen solution of

809813/1176

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elastomeric polyurethane according to Example 1 in dimethylformamide was obtained, squeezed out with wipers on both sides, the amount of impregnating liquid being adjusted to 10 to 11 times the weight of the mat. On the surface the so impregnated mat was then a 20% solution of elastomeric polyurethane in dimethylformamide in an amount that 2.5 times the weight of the fibrous mat was applied. Then the mat was allowed to precipitate into a 30% for 20 minutes aqueous dimethylformamide solution, after which the polystyrene of the fiber was extracted with toluene at 65 to 70 ° C. The on The layer obtained in this way had an apparent specific gravity of 0.5 to 0/6 and had a solid structure. Besides that the layer had due to the weak adhesion between resin and fibers and the presence of micropores in the fibers that caused by the extraction, a moderate flexibility. It had the structure of natural leather, as it is used for shoe upper leather. The properties are in the table below refer to.

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809813/1170

After the cowhide cowhide
Invention (chrome (lacquered)
upper leather) Sevicht (g / m) 880 553 1160 Thickness (ram) 1.43 O _; 96 1.80 Specific weight (g / cm) 0.61 0.58 0.64 Tensile strength (kg / 3 cm) 55 57 88 Tensile strength (kg / mm) along
χ across)
1 ^ 28 χ 1 _L 2 1j.97 1 ^ 63 Extensibility (%) 58 χ 57 57 74 31 permanent distortion
(1-fold) (%) 1/2 1.8 2/5 Permanent distortion
[10-fold) (%) 2.0 2.4 3.8 Shear strength (kg) 3.3 L ³ ' ² 5.3 tensile strength (time) more than
10,000 more than
10,000 more than
10,000 air permeability (min) 30th 3 more than
2 hours • "Eucntigen permeability
[Ga ^2/24 hrs.) 1280 2580 530

The synthetic leathers produced according to the preceding examples can be dyed or dyed by known methods, such as dyeing, spraying, coating or layering of a solution or emulsion of a high molecular weight substance or embossing, etc. provided with a smooth surface.

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809813/117 ^

Example 3

A mixture of 50 parts of 6-nylon and 50 parts of polystyrene was spun with an extruder in the melt process into filaments of 1.5 denier, which are stretched 6 times, wound up and curled at 18 / in. Then were cut them into fibers of 50 mm length, which with the help of a suitable device (random webber) and a needle loom cross-linked to a layer with three-dimensional

P structure have been processed. The layer was impregnated with a 6 % solution of polyurethane obtained by reacting an adipic acid-ethylene glycol polyester with diphenylmethane diisocyanate to form a prepolymer and reacting the prepolymer with a diol in tetrahydrofuran. Then it was immersed in water to precipitate the polyurethane. After drying, the molded body thus formed was ^{immersed in toluene at 90 °} C. for one hour in order to extract the polystyrene, then washed with methanol and dried.

j The finished molded body according to the invention was very flexible and leathery and had high elasticity.

Example 4

A surface of the pliable obtained according to Example 3 The shaped body was fired and the shaped body was then hot-pressed. Then a 7% solution of a high molecular weight of the polyurethane type as in Example 1 in dimethylformamide sprayed onto the fired surface as a very thin film.

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OC _

In this way, a synthetic leather very similar to natural leather was created Leather preserved.

Example 5

A mixture of 50 parts of polyethylene terephthalate and parts of polystyrene was spun by an extruder into filaments, which were hot drawn 5 times to a thickness of 2 denier. In the manner described in Example 3, the fibers were then processed into a layer with a three-dimensional network structure. This layer was impregnated with a 6% solution obtained by dissolving a mixture of parts of high molecular weight substance of the polyurethane type according to Example 1 and 40 parts of polystyrene in dimethylformamide, and then a 5% solution, which was obtained by Dissolving a mixture of 40 parts of high molecular weight substance of the polyurethane type, 30 parts of polyvinyl chloride and 30 parts of polystyrene in dimethylformamide was sprayed on to obtain a pitted surface. The layer was then precipitated with water and treated ^{with toluene at 80 ° C. to remove the polystyrene completely.} Finally, it was washed with water and dried.

Example 6

Mixed spun threads made from a mixture of 50 parts polyacrylonitrile and 50 parts polyvinyl alcohol (1.5 denier) were crimped at 18 / inch and made into staple fiber of 25 mm

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Cut to length from which a layer of 200 g / m 2 was formed with the aid of a suitable device (random webber) and a needle stick. After hot pressing with hot rollers, this layer was soaked with a 6% solution of polymethyl acrylate in toluene and pressed out with rubber rollers to a solution content which was 600 % of the weight of the layer. The same solution was then sprayed onto the surface of the layer and precipitated ^{with expressing in water at 40 ° C.} The polyvinyl alcohol was then extracted by storing the layer in water at 90 ^° C. and then washed with water and methanol. The synthetic leather obtained in this way according to the invention had the same external appearance, texture and other properties as natural leather.

Example 7

Mixed spun threads (1.5 denier) from a mixture

of 50 parts of polystyrene and 50 parts of polyethylene terephthalate ι

was crimped at 20 / inch and formed into fibers 3 cm in length cut up. This staple fiber became a three-dimensional arbitrary in the manner described in Example 6 Layer processed with a weight of 250 g / m. The layer was impregnated with a 6% dimethylformamide-acetone solution (1: 1) a high molecular weight polyurethane, which by reacting polyethylene adipate with diphenylmethane diisocyanate ■ to a prepolymer and further reacting the prepolymer "with a diol. Then the

809813/1178

The layer was squeezed out with rubber rollers with the solution content adjusted to an amount equal to 600 % of the weight of the layer. The same solution was applied to the surface of the layer and, after being left to stand for a short time, precipitated with a 30% aqueous dimethylformamide solution while squeezing out.The molded body obtained was ^{immersed in toluene at 80 °} C. for 60 minutes to completely extract the polystyrene of the mixed-spun fibers, then washed and dried. The artificial leather produced in this way had the same appearance, structure and other properties as natural leather

Example 8

Filaments spun in a mixture of 40 parts of 6-nylon and 60 parts of polyvinyl alcohol were ^{stretched 6 times at 200 °} C., filaments of 1.5 denier being obtained. The threads were crimped at 18 / inch and cut into fibers 50 mm in length. These were then processed into a layer with a three-dimensional network structure in a suitable device and a needle loom. The layer was impregnated with a 6-Xigen dimethylformamide solution of polyurethane, which had been obtained by reacting polyester from ethylene glycol and adipic acid with diphenylmethane diisocyanate and a diol, and then immersed in water to precipitate the polyurethane, at the same time the polyvinyl alcohol was extracted from the fiber Then it was washed again with water and dried *

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The molded article obtained in this way according to the invention was extremely flexible and leathery and had a high Elasticity.

Example 9

Mixed spun threads of 2 denier which are melt-spun process from a mixture of 45 parts of polyester from terephthalic acid and ethylene glycol and 55 parts of polystyrene 5 times obtained by an extruder and hot drawing were cut into fibers.

This was processed in the manner described in Example 8 to form a layer with a three-dimensional network structure which with a 6% solution of a mixture of 60 parts of high molecular weight Polyurethane according to Example 1 and 40 parts of polystyrene was impregnated in dimethylformamide. Then became a 5% solution of a mixture of 40 parts of high molecular weight polyurethane, 30 parts of polyvinyl chloride and 30 parts Polystyrene in dimethylformamide is sprayed on the pitted surface, after which the layer is completely removed of polystyrene and precipitation of the polyurethane in cyclohexane was treated by 50 C. Finally it was with methanol washed and dried.

The invention includes everything that is contained in the description, including that which deviates from the specific exemplary embodiments are obvious to the person skilled in the art.

Patent claims s BA / Hi - 16 676 809813/1178

Claims (1)

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