DE1635690A1 - Process for the production of leather-like, microporous surface structures - Google Patents

Description

VOF

Process for the production of leather-like microporous fabrics

United Glanzstoff-Fabriken AO Wuppertal-Elberfeld

It is known, leather-like fabric from a textile Produce base layer in which you can put an elastomeric binder equally distributed. For the formation of the textile base layer it is preferable to use felt-like non-woven fabrics Fiber mats, but can also be woven and knitted or multi-weave Find use. As elastomeric binders suitable for distribution in these base layers were for example polyurethanes, polyvinyl chloride and butadiene-acrylate copolymers known. These polymers are sprayed onto the textile layers in the form of solutions Dipping or squeegeeing applied. The polymeric binder introduced into the textile base layer is then precipitated. The best results have hitherto been achieved by treating the impregnated product with a non-solvent, which is at least partially miscible with the solvent for the applied binder. After impregnation and precipitation will wash away the solvent and nonsolvent and the finished product dried. Although these prepared base layers provided with an elastomeric binder have leather-like properties, let it be necessary to

BATH ORIGINAL -2-

109817/1921

Improvement of the surface structure and thus the appearance and the waterproofing of the impregnated base layer to apply a top layer.

Processes for forming cover layers have already become known. One proceeds in such a way that one polyurethane or mixtures of polyurethanes with polyvinyl chloride converted into the gel form and the gels on the textile orundic layer coagulated by treatment with nonsolvents, preferably water. The polymers are converted into gel form in such a way that a solution is first prepared - for polyurethanes, dimethylformamide is particularly suitable as a solvent - and a certain amount of non-solvent in the solution, like water or alcohol. The amount of nonsolvent is dosed in such a way that the polymer just gels. Such gels can be viewed as two-phase systems. In the at least one substance is dispersed in a dispersant, the dispersed substance and the dispersant represent interpenetrating coherent systems. Well that Application of the polymer gel to the textile base layer is used as a precipitation bath with water or a mixture of water Dimethylformamide.

When using this known process orphan, however, it has been found that it is seldom possible to produce cover layers which are completely free of macropores. A further disadvantage of the known methods for producing top layers is to be seen in the fact that the metering of nonsolvents and solvents must be adhered to very precisely. Even relatively small deviations, which can easily be verified operationally, lead to a gel structure that leads to undesirable results. "Macropores" are to be understood as meaning pores occurring in the top layer that are already old and stupid

TÖ9 8T7 / 1921

BATH ORIGINAL

. VOP 1281

Can be recognized by the eye, up to those that are still recognizable as small vacu © l © n on photographic cross-sectional recordings enlarged approximately to the It100 scale and are mostly directly on the surface of the cover layer have a very unfavorable effect on the moisture and water conductivity of the leather but also on its elastic properties. On the other hand, one speaks of a microporous deek »layer when no vacuoles show up in a photographic cross-sectional _{image Θ}

The present invention is an improved process for the production of leather-like microporous sheet composed of a text lien Grundschieht _s in an elastomeric binder is uniformly distributed, "as well as a covering layer composed. It has been found that microporous in a particularly advantageous manner covering layers chireh applying a polyurethane-containing polymer gel In © INEM suitable for polyurethane Lösungssiittel, precipitation obtained de © polymer followed by washing and drying k © AEI _D when after application of the gel to the Grundsehiefofe ül @ Precipitation at temperatures between 5 and 8o ° G with © in ©? ¹ wt.% Electrolyte solution which has a p - »value between 3 and 9 and an electrolyte concentration between 15% by weight and the sustaining value.

It is suitable for use in accordance with the method according to the invention practically all polyurethane © «that were converted into gel form permit. However, polyurethanes containing them are particularly suitable Polymer gels containing 15 to 35 percent by weight of a linear polyurethane, 0 to 15 percent by weight of one or more others

αϊ 0 9 8 1 7/1 9 2 1 BAD ORIGINAL

Until JO weight percent of a Nichtlösungsmlttels for polyurethanes and 20 to 80 weight percent polymer contained 5 of a solvent for polyurethanes by the non-solvent is at least partially soluble. A preferred embodiment provides for the use of polymer gels which contain 20 to 30 percent by weight of polyurethanes, 0 to 10 percent by weight of one or more other polymers, 5 to 15 percent by weight of nonsolvents and 45 to 75 percent by weight of solvents 20 ⁰ C have a viscosity of 20 to 10CF ⁰ ", are particularly suitable for conversion into the gel form.

The polymer gel to be used according to the invention can contain, in addition to polyurethane, one or more further polymers which are at least partially miscible with polyurethane. Preferably used as further gel component homopolymer polyvinyl chloride, polyvinyl chloride copolymers, butadiene / acrylonitrile or butadiene / styrene mixed polymers. Also chlorinated rubber or nitrocellulose are particularly suitable · Among the polyvinyl chloride copolymers are preferred to mention those with maleic anhydride or polyvinyl acetate. The nitrocellulose used preferably contains an N content of 10.8 to 14 percent by weight.

Some polymers suitable for joint processing with polyurethane are listed in Table I below.

Table I.

Examples of copolymers suitable for processing with polyurethane! a) Copolymers of polyvinyl chloride:

1) Vinyl chloride BO% by weight + ethyl maleate 10% by weight

Methylmaleate + 10% wt.

1098 1 7/2

BAD ORiGJNAL

2) vinyl chloride 80% by weight + methyl acrylate 20% by weight *

3) vinyl chloride 80 wt.Ji + methyl acrylate Io wt.Ji

+ Isobutylra alelnate Io wt. $

4) Vinyl chloride 87% by weight + vinyl acetate 15% by weight *

5) vinyl chloride 80% by weight + MalelnsKurediaethlester 20 Qeyt.fi

6) vinyl chloride 85 g by weight + vinylidene chloride 15 Oew.ji Ä

7) vinyl chloride 80 wt. # + Maleic anhydride 20 wt

8) vinyl chloride 70 Oew.ji + vinyl isobutyl ether JO Oew.ji

b) Butadiene / acrylonitrile mixture polymer

9) Butadiene 72% by weight + acrylonitrile 28 Oew.ji

10) Butadiene 10 Qe \ t, i6 + acrylonitrile 90%

(and all mixtures lying between these limits «)

c) styrene / butadiene copolymer

11) styrene 80 wt. £ + butadiene 20 wt. Ji

d) vinylidene chloride / acrylonitrile / methacrylic * te

10981

. Suitable nonsolvents for the preparation of the gels are Water and low molecular weight alcohols, such as methyl or ethyl alcohol, are well suited · The ones to be used according to the invention Oils preferably contain 5 to 10 as nonsolvents Weight percent water or 5 to 30 weight percent ammonium nitrate.

Good solvents for polyurethanes are known to be dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, ^ butyrolactam, J ~ butyrolaoton, 6-caprolactara. That to be used according to the invention Polymer gel preferably contains dimethylformamide as solvent.

The polymer gel containing polyurethane can be applied to the textile base layer by spraying, dipping or knife coating without particular difficulties. The aim should be an application in a layer thickness of 0.4 to 1.5 mm. 5 and 8 give the lying Pjj value. It has also been found that the presence of 5 to 10 weight percent dimethylformamide in the electrolyte solution can be very beneficial. Salt mixtures can also be used as the electrolyte, provided that the mixtures are soluble in water in the required concentration. According to a preferred embodiment, the concentration of the electrolyte solution should be between 20 percent by weight and the saturation value. The saturation value is to be understood as the electrolyte concentration which occurs when the precipitation bath is saturated at the temperatures provided for the precipitation, ie between 5 and 80 ° C. Particularly favorable results were obtained at a Oelfällung, which was carried out at temperatures between 15 and 60 ^0C.

.7.

10 9 8 17/1921

BATH ORIGINAL

635690 "VGP 1281

The optimal electrolyte concentrations required to achieve a microporous cover layer can easily be determined in each individual case by means of experiments. It turned out that "in general, no further advantages are achieved if the concentration of the salt solution is increased far beyond the minimum salt concentration required to achieve a microporous structure. Of course, resulting in a higher Salzkonzentratlon no disadvantages, so it is recommended that the required Mindestkonzen- {tratlon sufficient degree to work remotely · If you give abundant electrolyte one than the minimum concentration, calculated as the special additional advantage of erfindungsgenäßen process a relatively high operational reliability, since then, as was found,. Concentration fluctuations or temperature fluctuations in the end product have practically no effect «

A number of salts which can be used as electrolytes in the context of the invention and their solubility in water at 20 ^° C. are compiled in Table II below.

Table II Salt solubility in Water at 20 ^° C

NaCl - 26.4

NaNO, 46.8

NH ₄ Cl 27.1

NH ^ NO, 65.2

10 9 81 7 ⁸ Λ1 9 2 1

BAD ORtGJNAU

1B35690 vop I28i

KCl 25.6 %

ZnSO ^ 62.9 #

CaCl ₂ 43.0 %

(NH ^) ₂ SO ₄ 43.0 %

MgCl ₂ 75.2 %

Are preferably suitable for the precipitation of the polyurethane aqueous solutions of alkali »alkaline earth, ammonium or. Zinc salts. The precipitation of the polyurethane-containing polymer gel in the catfish according to the invention is not in itself attached to that Adherence to a certain precipitation time bound. However, longer tents than 15 minutes not required. Of course that depends on the precipitation of the oil depends on the temperature of the precipitation bath. Often times when it is very hot, close to 80 ° warm precipitation baths, the precipitation is complete after just 1 minute. To achieve a uniform top layer structure, it has It has been found to be particularly advantageous to carry out the precipitation of the oil with the electrolyte solution within 2 to 10 minutes. After the polymer gel has precipitated, the top layer is completely covered with water in a manner known per se Removal of solvents and nonsolvents and special washed of the salts and finally dried. It was found that the use of saline solutions, usually Wash tent required to remove unwanted foreign matter is not extended. The salts can be clearly seen easier to remove than the solvents wash out.

__ ..-- -9-1 0 9 8 17/1921 ^{BAD 0RIG} 'NAL

The outer layers produced according to the invention also have an excellent microporous structure has a significantly better flexural strength than top layers in which Macropores are included. In the case of top layers with macropores, the thin skin tends to break over in the endurance test the vacuoles on «At such a rupture point, the rupture in the top layer continues to tear very quickly Fatigue strength according to IUP 20 in a Ballyflexometer (Pa. BaIIy AO., Schönenwerd / Switzerland) it could be determined that macropore-containing top layers on average after 10000 plexings are destroyed, while the micro- I Porous top layers can withstand at least 2oo,000 flexings without damage.

The following examples are intended to explain the invention in more detail » example 1

According to known methods, the usual staple length was initially established by carding polyamide and regenerated cellulose fibers a fiber fleece is produced, which is then used as usual impregnated with a linear polyester polyurethane. After the textile fabric had been washed and dried, it was washed with A polymer gel with a thickness of 1.1 mm was applied using a doctor blade. The polymer gel was composed of 20 weight percent linear Polyester urethane, 4 percent by weight polyvinyl chloride, about 6 percent by weight ammonium nitrate and about 70 percent by weight dimethyl

-10-

BATH ORIGINAL 10 9 817/1921

formamid together. The coated with this polymer gel textile base layer, which is also called "substrate" it is then carried out through a length of 20 ° to 20 ° C adjusted sodium chloride solution. After a contact time of 5 minutes, it is washed with water and dried. The emerging The product has a very even and fine-pored top layer. Pores with a diameter of ΙΟ / ** were not observed. Most of the micropores formed were much smaller. The finished fabric showed a water vapor permeability of 65 ff / m / day. In a counter-attempt was the precipitation in a known manner with the help of pure Water carried out. The top layer was interspersed with micropores with a diameter greater than 20 / ".

Example 2

As described in Example 1, a fiber fleece is coated with a polymer gel. However, to carry out the precipitation an electrolyte bath was used which contained 20 percent by weight of sodium chloride and 10 percent by weight of dimethylformamide. The precipitation was carried out at a bath temperature of 50.degree. The resulting leather-like microporous sheet-like structure showed an extremely fine pore structure. The exam the water vapor permeability according to DIN 53533 gave a value of 750 g / m / day.

Example 3

A known method is used to produce aue polyamide and Regenerated cellulose short fibers on a paper machine one fiber

-11-

10 9 8 17/1921 BAD ORlGi? 4AL

-11- VGP 1281

fleece that is impregnated with a linear polyurethane mixed with polyvinyl chloride. After washing and drying a 0.8 mm thick layer of a polymer gel is applied to the substrate and has approximately the following composition has: 25 percent by weight polyurethane and 5 percent by weight of a copolymer, from 80 parts of polyvinyl chloride and 20 Parts of maleic anhydride, 10 percent by weight of water and 60 percent by weight of dimethylformamide. The appropriately coated The substrate is passed through a precipitation bath containing 32 percent by weight of potassium nitrate and with a residence time of 3 minutes set to 65 ° C 1st. After washing and drying it was made get a flat structure with a very finely porous top layer "

Example 4

As described in Example 3, a polymer gel is applied to a substrate made from a fiber fleece. The composition of the gel corresponds to that of Example 3, but instead of the polyvinyl chloride copolymer, the same amount of nitrocellulose was used. To precipitate the polymer gel, the coated substrate is passed through a 50 # strength ammonium nitrate solution, the temperature of which was 23 ^° C., for a dwell time of 8 minutes. After washing and drying, a sheet-like structure was obtained which, when the flexural fatigue strength was checked in accordance with IUP 20 with a Bally flexometer, remained undamaged after 500,000 flexings.

-12-

109817/192 1 BADOR ₁ G ₁ NAL

Example 5

A nonwoven fabric impregnated onto a polyurethane was used Polymer gel applied, which contained about the following substances »24 percent by weight linear polyester urethane, 6 percent by weight ammonium nitrate and 70 percent by weight dimethylformamide. For the precipitation of the in one layer thickness of 0.5 "in the applied polymer gel became a 30 ° warm aqueous 225έ electrolyte solution used, the 70 parts Contained sodium chloride and 50 parts potassium chloride. To a very fine-pored top layer was obtained after washing and drying. A photographic cross-sectional view showed a through and at a magnification of It100 due to the microporous structure of the top layer produced.

109817/192 1

Claims (1)

Claims 1) Process for the production of leather-like microporous flat structures, which consist of a textile base layer, in which an elastomeric binder is evenly distributed 1st, as well as a top layer are made by applying a polyurethane-containing polymer gel in a solvent suitable for polyurethanes, precipitation of the polymer with subsequent washing out and Drying is produced, characterized in that, after the gel has been applied to the base layer, the Precipitation at temperatures between 5 and 80 ° C with an aqueous electrolyte solution takes place in between 3 and 9 lying p ^ -value and one between 15 weight percent and the saturation value lying electrolyte * has concentration * 2) The method according to claim 1, characterized in that a polyurethane-containing polymer gel is applied to form the top layer, the 15 to 35 percent by weight of a linear polyurethane, 0 to 15 percent by weight of one or more other polymers, 5 to] 50 percent by weight of a nonsolvent for polyurethanes and contains 20 to 80 percent by weight of a solvent for polyurethanes, in that the non-solvent is at least partially soluble. 109817/1921 BATH ORIGINAL -14- VQP 1281 3) Process according to claims 1 and 2, characterized in that the Polyraergel contains 20 to JO weight percent polyurethane, 0 to 10 weight percent of one or more other polymers, 5 to 15 weight percent non-solvent and 45 to 75 weight percent solvent * 4) Method according to claims 1 to 3, characterized characterized in that linear polyurethanes are used which, in 20 # strength DlmethylformanildlOsung at 20 ⁰ C have a relative viscosity of 20 to poise. 5) Process according to claims 1 to 4, characterized in that the polymer present in the gel is homopolymeric polyvinyl chloride or polyvinyl chloride copolymer, preferably with maleic anhydride or with polyvinyl acetate used" 6) Process according to claims 1 to 4, characterized in that there is another polymer present in the gel butadiene / aorylnitrile and / or Butadiene / styrene mixed polymers used. -15- .0 9 81 7/1921 BAD original 7) Process according to claims 1 to 4, characterized in that there is another present in the OeI Polymeric nitrocellulose used « 8) Process according to claims 1 to 7 »characterized in that one is used as a non-solvent 5 to 10 weight percent water is used. 9) Process according to claims 1 to 7, characterized in that one is used as a non-solvent 5 to 30 weight percent ammonium nitrate is used. 10) Process according to claims 1 to 9 »characterized in that the solvent Dimethylformamide is used. 11) Process according to claims 1 to 10, characterized in that the precipitation is carried out at temperatures between 15 and 60 ° C. 12) Process according to claims 1 to 11, characterized in that the precipitation is carried out with an electrolyte solution which has a power between 4.5 and 8. -16- 109817/1921 _wawlft IJ) Process according to claims 1 to 12, characterized characterized in that the precipitation is carried out with an electrolyte solution «the one between 20 percent by weight and the saturation value lying electrolyte concentration. 14) Method according to claims 1 to 13 »thereby characterized in that the electrolyte solution additionally contains 5 to 10 Oewlchtzentrale dimethylformamide. 15) Method according to claims 1 to 14, characterized characterized in that alkali, alkaline earth, ammonium or zinc salts are used as the electrolyte 16) Process according to claims 1 to 15, characterized in that salt mixtures are used as the electrolyte. 17) Method according to claims 1 to 16, characterized characterized in that the gel is precipitated with the electrolyte solution within a period of time from 1 to 15 minutes. l8) Process according to claims 1 to 17 * thereby characterized by the fact that the geis are precipitated with the electrolyte solution within a room of 2 to 10 minutes. • "" "—INAL