DE1444165B - - Google Patents

Description

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The invention relates to a method for producing essential colloidal dispersion only at very low

of vapor-permeable synthetic leather with microporous measurement of the amount of the polymer

this polymer layer is obtained in the form of nonsolvent added with microporous solution.

Porous fibrous material provided with coatings If too much nonsolvent is added, the

layers or self-supporting microporous poly- 5 is a gel that, in the sense of the French patent

Merisatfolien by applying a layer of a blotting script for the production of the microporous covering is not

Solution of a polymer in an organic solution can be used.

medium on the fibrous material underlay or an impermeable According to an older proposal (German open-label Carriers, coagulating the in the layer against (14 44 164) can cause this disadvantage retained polymer and removal of the solvent io avoided that one to the polymer solution means of the layer by treating the coated a sufficient amount of water or another Carrier with a miscible with the solvent, nonsolvent for the polymer added to the polymer non-dissolving liquid and the mixture in a polymeric gel portion and a final drying, as well as in the case of use to make the liquid fraction separable, whereupon the an impermeable carrier stripping off the micro-gel fraction and for coating the sub-porous layer of the same. location is used.

Such methods are known per se and are suitable. The object of the invention is to provide a versieh for the production of artificial leather of good improved process for the production of steam permeability. to provide casual synthetic leather that

For example, French patent specification 1 197 876 20 permits on the one hand the rapid coagulation of the polymer, a process for the production of microporous foils to form a microporous layer, on the other hand lien or coatings by applying hygroscopic, the production of an essentially colloidal polyurethane solution on carrier and Removal of polymer dispersion by adding a very precisely measured amount of nonsolvent to the solvent by washing with water, in which one avoids merisate solution using solutions and finally not using a gel for polyether urethanes in hygroscopic solutions Coating instructed mean the carrier coated with the solution is through, which has to be separated from the air in a special process stage of the action of a humid atmosphere from a liquid portion.
Lets water attract, whereby the polymer solution Product dries. from the point in time at which the solvent has been removed from the polymer in the polymer layer until the time-coated layer takes place very slowly, which is a disadvantage for point at which the non-solvent means the mass production. 35 polymer layer has been removed, a maximum

An improvement of this known method is elastic deformation ^{resistance of at least 7 kg / cm 2} described in French patent specification 1,225,729, and where appropriate, the ben. This patent specification describes a process for polymer solution in addition to a non-solvent miscible with the organic production of foils or coatings on porous solvents for the fiber-like substrates, which are particularly suitable as leather 4 ° polymer in amounts of about 40 to 95% of the substitute materials, which consists of it that the amount that would lead to the incipient conversion of a polymer solution, the at least one vinyl poly solution in a colloidal polymer dispersion and / or a chain extension of the add, and the coagulation reaction product of at least one polyalky- des Polymer by treating the coated lenätherglykol and at least one diisocyanate with 45 carrier with a mixture of an organic aid of a two-functional, amino nitrogen-containing solvent for the polymer and a reactive hydrogen atom bonded solvent at least partially miscible non-group-containing compound containing poly-solvent for the polymer in the case of a weight urethane in an organic solvent, the ratio of solvents to nonsolvents does not dissolve the polymer and with the organic 50 of 10:90 to 95: 5,
see solvent miscible, against the polymer It should also be mentioned that from the German Aus and the underlay ineite liquid up to the formation of legal documents 1 004 136 and 1 084 686 process for a cloudy or opalescent dispersion of fine- Production of porous "breathing" Fiber art-dispersed polymer is added, the dispersion on a leather is known, in which the synthetic leather bil-impermeable underlay or soluble fibers are added to a porous fibrous fiber layer, applies like underlay, the coated underlays are then removed later. In this case, the polymerizate and the coagulation of the layer form but no microporous products,
An essential feature of the invention is that the organic solvent does not dissolve and with the organic solvent that it is not a dispersion, miscible solvents, inert to the polymer and the base applied to the substrate, but rather a solution of the polymer Liquid treated and that is so that there is no risk that the product already held dries and, in the case of use, coagulation occurs after application. After an impermeable base, the polymer layer, preferred embodiment of the invention, can be stripped from the base. This process allows a solution of the polymer in it as a starting solution, microporous films an organic solvent can be used much more quickly, or coatings which are particularly suitable as those which are already a nonsolvent in amounts of 40 leather substitutes, but has the disadvantage that contains up to 95 ° / ₀ that amount, the formula used to beginnendie for coating the substrate, in the conversion of the solution in a colloidal di-

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Spersion would be required, so that even with this Aus capable hydrogen atoms-containing polymers, such as management form no risk of premature coagulation, a polyalkylene ether glycol or a polyester lation of the solution. Ultimately, the hydroxyl terminated by it becomes a poly selection of the polymers according to their maximum urethane with terminal isocyanate groups elastic deformation resistance ensures that 5 and this prepolymer with a chain extension in the coagulation resulting micropores can react in the medium, in the case of two more reaction The course of the procedure does not disappear again. capable hydrogen atoms to amino nitrogen atoms ; Contrary to the procedure of the French are bound. Hydrazine and N-methyl-bis-amino-J patent specification 1,225,729 will result in the beneficial eropropylamine being used as a chain extender the preferred embodiment of the- i ° preferred; however, other chains according to the invention can also be used Process achieved by using a lengthening agent, such as dimethylpiperazine, Non-solvent for the solution of the polymer 4-methyl-m-phenylenediamine, m-phenylenediamine, 1,4- ■ in a wide range of endpoints is added, the diaminopiperazine, ethylenediamine or mixtures below and outside the endpoint range of the same.

known procedure. 15 The polyurethane elastomer can be manufactured

Process according to the invention does not run the risk of initially having a molar excess of

the end point in the formation of a polymer diisocyanate with the reactive hydrogen

spersion is missed. The polymer according to the invention containing atom mixed and that

Driving is even surprisingly effective when the mixture is heated to around 50 to 120 ° C until the

the polymer solution has not formed any non-solution prepolymer at all. You can do the same

medium is added. The process allows diisocyanate with a molar excess of the

a relatively rapid coagulation of the coating containing reactive hydrogen atoms poly-

in a liquid bath, without the coating initially reacting and the reaction product

an atmosphere of carefully controlled humidity - in turn with further diisocyanate to the pre

activity content needs to be exposed, as it does with 25 polymerisat implement.

the process of French patent specification 1197 876. For the preparation of the prepolymer you can

is required. Furthermore, in the inventive aromatic, aliphatic, cycloaliphatic diiso-

Process do not use phase separation, the cyanates or mixtures thereof. Such

Turning an extremely viscous coating compound Diisocyanates are z. B. toluene-2,4-diisocyanate, To-

of high solids content required, as it is according to 30 luylen - 2,6 - diisocyanate, m - phenylene diisocyanate, bi-

the older proposal of the German disclosure phenylene-4,4'-diisocyanate, methylene-bis- (4-phenyl-

font 1 444 164 is the case. isocyanate), 4-chloro-1,3-phenylene diisocyanate, naph-

Since the polymer solution in the case of the ethylene-l, 5-diisocyanate, tetramethylene-l, 4-diisocyanate of the invention, the process should never be converted into hexamethylene-l, 6-diisocyanate, decamethylene-l ^ O-di- ^! it comes dangerously close to its gel formation point, 35 isocyanate, cyclohexylene 1,4-diisocyanate, methylene it is practically free of polymer gel particles. The bis (4-cyclohexyl isocyanate) and tetrahydronaphthy occasional occurrence of such gel particles was an alkali diisocyanate. Arylene diisocyanates, ie isocyanates, a disadvantage of the older methods in which one worked with an aromatic solution in which the isocyanate groups bonded very close to their gel ring, are preferred. They respond to education; this is because the gel particles generally lead to 40 faster than the alkylene diisocyanates. a reduction in the evenness of the covering as it contains reactive hydrogen atoms and its resistance to damage Polymers are used in the manufacture of Voipoly when bending. merisats polyalkylene ether glycols are preferred. The on

According to a particularly preferred embodiment, the most suitable polyglycols have molecular

Form of the invention is the solution of the polymer, 45 weights from 300 to 5000, preferably from 400 to

before it is applied to the carrier, with a 2000; they include B. polyethylene ether glycol,

at least partially mixed with the solvent- polypropylene ether glycol, polytetramethylene ether glycol

non-solvent for the polymer in a kol, polyhexamethylene ether glycol, polyoctamethylene

Volume mixed ° / ₀ of that amount to 95, the ether glycol, Polynonamethylenätherglykol, Polydeca-

Polymer solution not yet in an essentially 5 ° methylene ether glycol, polydodecamethylene ether glycol

colloidal polymer dispersion to pass over and mixtures of the same. Polyglycols, which are several

lets begin. To this end, the addition of the various radicals contained in the molecular chain is

Non-solvent interrupted before the poly ζ. B. the compound HO (CH ₂ OC ₂ H ₄ O) _n H, at the η

merisat begins to take the form of colloidal or im an integer greater than 1 means can also

essential colloidal particles used in contrast 55.

to the relatively clear appearance of the poly-polyesters, which are used in place of the polyalkylene ether glycols

merisate solution is a cloudy or iridescent dispersion or can be used together with the same

result to be eliminated from the solution. The expression can include, for example, those who implement through

"Polymer" is used here for polymeric, film-forming carboxylic acids, esters or acid halides

Substances used that are either obtained from a pure poly-60 with glycols. _ Suitable glycols

merisate or from mixtures of such with zu- are polymethylene glycols, such as ethylene, propylene,

Sentences, e.g. B. hardeners, coloring additives, tetramethylene, decamethylene glycol, substituted

Plasticizers, stabilizers and fillers, polymethylene glycols such as 2,2-dimethylpropanediol

exist. 1,3, cyclic glycols, such as cyclohexanediol, and aro-

For the production of artificial leather, 65 matic glycols, such as xylylene glycol. When the micro-

Polymer component of the polymer solution Poloporous products have the greatest possible flexibility

urethane elastomers which are to be produced are preferred, aliphatic glycols are preferred

by adding a diisocyanate to a reaction. These glycols are mixed with aliphatic, cyclo-

aliphatic or aromatic dicarboxylic acids, lower alkyl esters or ester-forming derivatives thereof converted to polycondensates of relatively low molecular weight, which preferably have a melting point of less than about 70 ⁰ C and the same molecular weights that were specified for the polyalkylene ether glycols. Acids for the production of such polyesters are, for. B. succinic acid, adipic acid, suberonic acid, sebacic acid, terephthalic acid and hexahydroterephthalic acid and the alkyl- and halogen-substituted derivatives of these acids.

The chain extension reaction is usually carried out at a temperature below 120 ^° C. and often at room temperature, especially when hydrazine is used as a chain extension agent. In this reaction, the molecules of the prepolymer combine with one another to form an essentially linear polyurethane, the molecular weight of which is usually at least 5,000 and sometimes even 300,000. The reaction can be carried out without a solvent using a high-performance mixer or in a homogeneous solution. In the latter case it is advisable to use one of the same organic solvents that are used to prepare the polymer solution.

Since the resulting polyurethane has rubber-like elasticity, it is referred to as an »elastomer«, although the degree of rubbery elasticity depends on the chemical structure of the polymer and the in combination with the same substances used from one product to another within further Limits can fluctuate.

Another preferred component of the polymer solution in the production of artificial leather is a polymer of vinyl chloride. A particularly high abrasion resistance of the product is achieved if a polymer of vinyl chloride is used together with an elastomer such as the polyurethane described above. For the production of artificial shoe upper leather from a mixture of a polyurethane elastomer and a polymer of vinyl chloride, the former is generally preferably used in a predominant proportion (more than 50 percent by weight) and the latter in a smaller proportion (less than 50 percent by weight). Suitable polymers of vinyl chloride are polyvinyl chloride and copolymers, which, preferably at least 80 ° / _0, of vinyl chloride and a minor portion of another ethylenically unsaturated monomer such as vinyl acetate, vinylidene chloride or Maleinsäurediäthylester, consist for the greater part.

Many other polymers, either alone or in combination with one another, can also be used as the polymer component of the polymer solution. The polymer component is selected so that it has a maximum from the point in time at which virtually all of the solvent for the polymer has been removed from the solution layer on the support to the point in time at which virtually all of the nonsolvent has been removed from the layer elastic deformation strength of at least 7 kg / cm ² (preferably about 9.14 to 21 kg / cm ² ). The liquids and the temperature in the process stages of coagulation and drying are further factors which, together with the properties of the polymer, influence the maximum elastic deformation resistance, and these factors are adjusted to the respective properties of the polymer component so that the maximum elastic deformation resistance of the polymer component does not drop below 7 kg / cm ^a. Various additives that can be contained in the polymer component also influence the maximum elastic deformation resistance.

ίο So z. B. the maximum elastic deformation resistance is reduced by plasticizers and by Fillers increased.

The maximum elastic deformation resistance of the polymer component used to produce the microporous layer is determined by measuring the curve of the dependence of the relative elongation on the stress on a pore-free (e.g. cast from solution) film of the polymer and entering it in a diagram and a Tangent from the initial rectilinear part of the strain-stress curve. From the point at which the tangent separates from the strain-stress curve, the perpendicular is dropped on the stress coordinate, and this point on the stress coordinate indicates the maximum elastic deformation strength. If the polymer is used in a mixture with additives, the maximum elastic deformation strength is measured on the mixture of polymer and additives. The strain voltage values are preferably with an Instron tensile tester at a strain rate of 100 ° / ₀ per minute at a 12.7 mm wide and about 0.25 to 0.5 mm thick rectangular sample at an initial distance of 25.4 mm determined between the gripper jaws. The test temperature for determining the maximum elastic deformation resistance of the respective polymer by this method is taken to be the highest temperature to which the microporous covering is exposed in the process according to the invention during coagulation and drying. In order to determine the effect of the coagulation liquid during drying on the coagulated product still soaked with the liquid, the maximum elastic deformation strength is determined on a pore-free, saturated sample in equilibrium with the last coagulation liquid used before drying. The polymer component and the coagulation liquid are then selected so that the polymer component in the coating at the end of the process stages of coagulating and removing the solvent, when the coating is removed from the coagulation liquid, and during and after the drying process stage, a maximum elastic deformation resistance above the limit given above.

The polymer component can have an initial maximum elastic deformation strength of slightly less than 7 kg / cm ² if, at the point in time at which practically all of the solvent has been removed from the layer, the maximum elastic deformation strength of the polymer is at least 7 kg / cm ² has risen. If the maximum elastic deformation resistance of the polymer component is too low, the product has no or only insufficient vapor permeability because the micropores during drying, especially towards the end of the drying process (ie during removal

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the last fractions of the nonsolvent) together - ethanol, hexane, benzene, gasoline, toluene, tetrachloride, ethylene, chloroform. If possible, be water

Within the above range of and mixtures thereof with water-miscible

maximum elastic deformation strengths, liquids can be preferred.

the polymer component of the solution, which is added to the polymer solution before the water or the other non-dissolving layers of the carrier is used, will contain several types of polymers, for which it is preferably with a substantial amount, eg. B. the following examples are given: Polyurethanes, about 2 to 5 times its own weight, of vinyl halide polymers, polyamides, polyester an organic solvent of the same amide, polyester, polyvinyl butyral, poly-a-methyl io type, as it to produce the polymer solution, styrene, polyvinylidene chloride, alkyl ester of acrylic is mixed. The addition of the non-dissolving acid and methacrylic acid, chlorosulfonated polymer to the solution should be made gradually with stirring, ethylene, copolymers of butadiene and acrylic, in order to avoid local coagulation.
Acid nitrile, cellulose esters and ethers, polystyrene and the nonsolvent may be added at most in such other polymers of vinyl groups containing 15 that the solution just barely monomers. Synthetic organic polymers are not preferred in a colloidal dispersion of Polymerisatwerden in general, and begins to move particles elastic poly-, and this amount bemerisate of relatively high molecular contributes about 40 to 95 ° / _0, preferably 70 to 90 ° / _0, the weight are particularly preferred. Amount, when added, the first signs of a

If the polymer used occurs with soft cloudy colloidal dispersion. If the

Makers is compatible, such as B. Vinylchloridpoly- Polymerisatlösung was initially clear, it is with the

merisate, it can normally also be used with known plasticizers in the process according to the invention

such amounts are mixed that the maximum after the addition of the nonsolvent is still in the

elastic deformation strength not less than 7 kg / cm ² essentially clear.

sinks. In addition, the polymer component can also be added to the polymer solution

other known additives, such as pigments, fillers, a thickener to add before this on the

Stabilizers and anti-oxidation agents, beige-carrier is applied to increase, preferably-

be mixed. wise a considerable increase in the viscosity of the

The polymerization component is brought about in a solution. This is especially true then

organic solvent to a solution of the 30 is expedient if a solution is used

desired solids content and the desired level of little or no nonsolvent

Viscosity solved. Has been clogged for application with the squeegee.

a solution is preferably used which, after the addition of nonsolvent to the solution of the addition of the nonsolvent, if such an excess polymer is added, in particular in the above-mentioned main, a polymer content of 35, range from 40 to 95 ° / ₀ , ' In the method according to the invention, about 10 to 30 percent by weight and a viscosity-moderate method is usually preferred because it has from about 10 to 500 P. The in the polymer this measure helps to prevent the formation of solution and larger cavities used in the coagulation liquid in the coating, organic solvents should be relatively less with the non-dissolving, especially if the carrier is a fibrous web of medium miscible, preferably completely miscible 40 Be liquid permeability. Ν, Ν-Dimethylformamide is in view of its is and the coated material is quickly immersed in the Koaguhhigh dissolving power for many of the preferred polylation liquid. This is based on its good miscibility with the fact that the presence of a considerable amount of preferred non-dissolving liquids includes non-solvents in the polymer solution, making water the preferred solvent for the use therein of a smaller amount of organic soluble polymers. Other suitable solvent solvents for the polymer in the process medium are dimethyl sulfoxide, tetrahydrofuran, tetra stage of coagulation, which in turn methylurea, N, N-dimethylacetamide, N-methyl- reduces the tendency of the coagulation liquid 2-pyrrolidone, ethyl acetate, dioxane, Butylcarbinol, in the first stages of the coagulation process, is toluene, phenol, chloroform and γ-butyrolactone. To force 50 air bubbles out of the carrier into the pavement. Mixtures of these solutions can also be used. In other words, the content of nonsolvents in the liquid, such as ketones and alcohols, which are miscible with water in the coagulation liquid, which can generally be higher, the higher the face alone, often poor Solvent for the poly content of the polymer solution is nonsolvent, are merisat. A very valuable mixture consists of 55 and vice versa.
Dimethylformamide and methyl ethyl ketone. Another reason why adding non-

An optionally applicable, but generally solvent, to the polymer solution in the area

preferred process stage after the production of the from 40 to 95 ° / ₀ of the initial conversion

Polymer solution consists in that the solution with the coating material from the state of a

a nonsolvent for the polymer dissolves in that of a colloidal dispersion

is mixed, with a required amount being usually preferred as the nonsolvent

Liquid used with the organic of that at the process stage of coagulation

Solvent in the solution at least partially faster coagulation conditions can be used

is miscible. Non-solvents, which in the sense of the can without the emergence of a product

Invention to be mixed with the polymer solution 65 with fine micropores, high vapor permeability

are water, ethylene glycol, glycerin, glycol and resistance to repeated bending as a result

monoethyl ether, hydroxyethyl acetate, tert. is affected. Under certain circumstances, each

Butyl alcohol, 1,1,1-trimethylolpropane, methanol, but little or all of the coating solution

no nonsolvent too, e.g. B. if allowed or desired, slow coagulation processes to be used, or if other properties of the product than those specified above are important.

An experienced operator has little difficulty in determining the most favorable amount of nonsolvent which must be added to the solution of a particular polymer in order to obtain a particular product. An inexperienced operator can easily determine the most favorable range of nonsolvents beforehand by doing a little preliminary experiment. He can z. B. to five small samples of the main mass of the solution 0%, 30 ° / ₀ , 60 ° / _? , 80% or 90 ° / ₀ non-solvent, based on the previously determined amount required for the initial conversion of the solution into a colloidal dispersion, then carry out the process within the meaning of the invention and according to its judgment, which is for the intended Select the most suitable sample for the intended purpose and calculate the corresponding amount of nonsolvent that he then has to add to the bulk of the solution.

After adding the nonsolvent to the polymer solution (if such a nonsolvent is added at all) a layer of the solution is applied to a carrier. The application can e.g. B. with a doctor blade, by pressing, dipping, spraying, brushing or rolling.

Synthetic leather and similar reinforced, vapor-permeable laminates are made by a layer of the solution on one or both sides of a flexible, porous fiber support, ζ. Β. on a nonwoven, unsized paper, woven or knitted fabric, leather, suede or artificial Leather. The fibers of the backing can be natural or synthetic, crimped or straight, organic or inorganic continuous filaments, staple fibers or fibers of the length of the paper pulp fibers being. After coagulation and drying, the solution layer turns into a microporous polymer layer, which is firmly united in one piece with the carrier.

A self-supporting microporous film is obtained by applying the solution layer to a removable one Carrier, preferably a smooth, impermeable carrier such as polished glass, stainless steel, Aluminum foil, plastic foil or one coated with a covering that facilitates detachment Fiber carrier, subsequent coagulation, removal of the solvent, drying and stripping.

The layer of the polymer solution located on the carrier is mixed with a organic solvent for the polymer and one with the solvent at least partially miscible non-solvents for the polymer treated, - until they form a cellular structure of interconnected micropores is coagulated. The weight ratio of solvent to Non-solvent in the treatment or coagulation liquid should be 10:90 to 95: 5. Therefor Suitable solvents and nonsolvents are the same as those already used for making the Polymer solution were specified. Usually one works preferably with a treatment or coagulation liquid with a solvent content of at least 50 percent by weight.

Preferably, the solution layer is immediately in contact with a mass of the coagulation liquid either by dipping it quickly or by putting the layer on the first Allows liquid to float. The coagulation process step can, however, also be carried out by exposing the layer to a spray mist or a vapor of the coagulating liquid, or by a combination of these or other known methods.

The preferred weight ratio of solvent to nonsolvent in the coagulation liquid is usually about 50:50 to 95: 5 and especially about 70:30 to 90:10. It is seldom appropriate to work with a ratio below 40:60. The best ratio to be used in each case depends largely on the amount of nonsolvent that was added to the polymer solution, the viscosity of the layer of polymer solution carried by the carrier, the viscosity and the temperature of the coagulation liquid and the fact whether the coagulation liquid is in In the form of a uniform body of liquid or in finely divided form, e.g. B. as a spray or steam is applied. If you z. B. adding in the production of artificial leather from a polymer solution of the solution 50 ° / ₀ that amount of water would occur if the initial signs of the formation of a colloidal dispersion, and the aufgetragnen layer in a mixture of 70 parts dimethylformamide and 30 parts of water at 20 ° C and it is found that the coagulated layer is "large-pored" instead of microporous (i.e. that the layer contains pores that are visible to the naked eye), then it is advisable to take a sample of the solution and add more water. z. B. about 80% of the amount at which an initial conversion of the polymer solution into a colloidal dispersion would take place. If the coagulated layer then still has large pores, it is advisable to modify the process in one or more of the following respects: (a) To increase the viscosity of the layer to be applied, for example by increasing the solids content of the polymer solution by replacing part of the polymer by another polymer, which provides a more viscous solution, or by adding a thickening agent; (b) to increase the viscosity of the coagulation liquid, e.g. B. by replacing part of the water with glycerine; (c) the temperature of the coagulating liquid, e.g. B. to 50 ° C to increase; (d) to apply the coagulation liquid in the form of a fine mist; (e) the quantitative ratio of dimethylformamide to water in the coagulation liquid, e.g. B. to about 90:10.

If the carrier is a relatively dense fibrous web and there is a tendency for bubbles, air pockets or similar larger voids to form in the coating when the coated web is immersed in the coagulation liquid, it is not advisable to start the coated carrier with the coated side down at least to float on the coagulation liquid so that air trapped in the carrier is not forced into the coating. This is particularly recommended when the polymer solution to no non-solvent has been added little or and the coagulating liquid has a content of organic solvent in the vicinity of the maximum allowable value of about 95 ° / _0th

In the process stage of coagulating a The ratio of organic solvents to non-solvents of more than 95: 5 is avoided, so that the coagulation liquid does not have such a strong dissolving effect on the covering that a sufficient one Coagulation with the formation of micropores is prevented or the pores that are formed to coincide.

On the other hand, particularly with the preferred polyurethane and polyvinyl chloride resins and mixtures thereof, there is usually no benefit in using a coagulation bath with a solvent content lower than that required for the solvent to nonsolvent ratio to be 70:30. This also applies in the event that up to about 95% of the amount of nonsolvent has been added to the polymer solution which would be required to bring about an initial conversion of the solution into a colloidal dispersion. However, this does not mean that with certain polymer solutions or under certain process conditions it could not be advantageous if the ratio of solvent to nonsolvent is less than 70:30 or less than 50:50. In general, however, there is a tendency for pore collapse at the lower ratios. As mentioned earlier, the desired pore formation can often be controlled by other means, one of the most practical of which is to keep the temperature of the first coagulation bath well above room temperature, e.g. B. to about 40 to 60 ⁰ C to increase.

In the next stage of the process, practically all of the solvent for the polymer is removed from the coagulated microporous layer removed before at least the last significant amount of nonsolvent is removed from it. This is done by treating the microporous layer with water or another nonsolvent for the polymer, which at least partially with the solvent for the polymer is miscible until the layer is practically free of the solvent. Because of this Washing out of the solvent from the polymer layer prevents the micropores when subsequent removal of the nonsolvent, which is still after washing out the solvent remains in the layer, largely or completely collapse.

To wash out the solvent and coagulate the polymer, the layer can be in a separate one Bath of nonsolvent or in a series of baths with gradually decreasing Solvent content can be immersed. One can also have a stream of the nonsolvent in the first bath initiate, while the layer remains in the bath, until the solvent content of the bath and thus the The solvent content of the layer has fallen to or almost to zero. After another process can use the nonsolvent throughout the washing and coagulating stage or part thereof in finely divided form, e.g. B. as a spray, are used.

The drying for removal of at least the last significant portion of the non-solvent is preferably carried out in a heating zone with air circulation at a temperature of about 80 to 130 ⁰ C.

This method results in microporous layers that are surprisingly smooth and free of the "Orange peel-like" surface irregularities are the most similar to those known so far Have products of this type.

If the microporous films obtained by the process according to the invention at or after their Formation can be combined into one piece with a porous fiber carrier, one can create an artificial leather that surpasses the previously known leather substitutes or even natural leather in many respects. So you can z. B. Manufacture artificial shoe upper leather, which leather-like appearance, durability and is convenient to wear without sacrificing the large periodic fluctuations in cost and having to accept properties that occur in natural leather. Furthermore, manufacturability means of the product in continuous lengths of any width and in a uniform, flawless condition a significant advance compared to natural leather for such purposes as upholstery

Extra covers, luggage, table and roller coverings, paint rollers and sports jackets.

The inventive method is suitable for the rapid and economical production of vapor-permeable Artificial leather, which is partially or completely made of a microporous polymer layer consists. In the process according to the invention, a constantly constant yield can be achieved achieve a uniform upper leather of a high quality.

The more important advantages of the method according to the invention can be briefly summarized as follows :

The most favorable endpoint range for adding nonsolvents to the polymer solution is so far that there is little risk that the endpoint will be missed, the solution unusable and the end product becomes faulty.

Valuable results are also achieved if the polymer solution is not given any nonsolvent clogs.

The best results are obtained when the layer of the polymer solution is immediately applied Brings contact with a body of liquid, in order to coagulate it relatively quickly and economically, without first conditioning the layer in an atmosphere of precisely controlled humidity needs to become.

The polymer content and the viscosity of the polymer solution used for coating can can be varied within wide limits, so that the process can be applied to any coating method and any Layer thickness can be adjusted.

There is no phase separation stage before the polymer solution is applied to the support will.

The products obtained by the process have improved smoothness, uniformity and flexural fatigue strength.
In the following examples, all amounts relate to amounts by weight, unless otherwise stated.

example 1

It is a 20 / manufactured ° _o by weight solution of a polyurethane elastomer by first Polytetramethylenätherglykol 3343 parts toluene diisocyanate 2,4-mixed by a molecular weight of about 1000 with 291 parts and the mixture 3 hours

heated to 90 ° C. 2485 parts of the resulting hydroxyl-terminated dimer are mixed with 570 parts of methylene bis (4-phenyl isocyanate). The mixture is heated to 80 ° C. for 1 hour, during which it changes into a prepolymer with terminal isocyanate groups. The prepolymer is dissolved in 10,000 parts of N, N-dimethylformamide (also referred to as dimethylformamide) and the solution is slowly added to a solution of 50 parts of a chain extender in 1710 parts of dimethylformamide. The chain extender is a mixture of N-methyl-bis-aminopropylamine and hydrazine hydrate in a molar ratio of 40:60. The reaction mixture is stirred for 30 minutes at 40 ° C., whereby a polyurethane solution with a viscosity of about 115 P and a polymer content of about 20 ° is obtained / ₀ receives.

A polymer solution consisting of 10.5 ° / ₀ Polyurethanelastomerem, 5.7% polyvinyl chloride and 83.8 ° / ₀ of dimethylformamide is prepared by reacting a 12 ° / o solution of polyvinyl chloride in dimethylformamide with the required amount of the above hergestellten20 ° / ₀ igenPolyurethanlösungmischt. By casting a pore-free film from a sample of the solution, treating for several days in water and determining the maximum elastic deformation strength by the method given above, the maximum elastic deformation strength of the polymer component of this solution is determined to be 12.65 kg / cm ² . At 100 ° C., the temperature used for drying the coated textile material in this example, the film has a maximum elastic deformation strength of more than 7 kg / cm ² .

10 parts of a mixture of 1 part of water and 4 parts of dimethylformamide are gradually added with stirring added to 100 parts of the polymer solution. Water is a nonsolvent for the polymer component of the solution and is highly miscible with dimethylformamide, which is used as a solvent serves.

If the mixture of nonsolvent and solvent is slowly and carefully added to a sample of the polymer solution in such an amount that there are initial signs of the transition of the solution into a cloudy, essentially colloidal dispersion, then it is found that this is 18 parts of the mixture required are. If about 2 more parts are added, the solution comes very close to its gel point. The amount of to be added in this example, the solution is non-solvent as .10 / 18 x 100 = 55.5 ° / ₀ that amount which would have to be up to the occurrence of the first signs of the formation of a colloidal dispersion.

The polymer solution modified by the addition of water, which does not yet have a milky appearance or iridescence, is applied by means of a doctor blade to one side of a porous, non-woven fiber material in a wet layer thickness of 1.65 mm. The non-woven textile is a fiber fleece impregnated with a polyurethane elastomer, which is produced according to Example 1 of US Pat. No. 3,067,483 or German Auslegeschrift 1,419,149. The nonwoven has a basis weight of 220.4 g / m ^2, and by needling a mat of shrinkable Polyäthylenterephthalatfäden of 0.5 and the impregnation with about 35 ° / _0, based on the fiber content of the mat, similar to a chain-extended polyurethane elastomers with hydrazine that described in this example with the difference that the chain extender in this case consists exclusively of hydrazine. The coating process is carried out at 21 ⁰ C and a relative humidity of 2O ° / o> dner for coating güntigen room atmosphere.

The layer of polymer solution applied to the nonwoven fabric is quickly coagulated to a porous structure by allowing the coated material to ^{float with the coated side down for 30 seconds at 27 °} C. on a mixture of 90 parts of dimethylformamide and 10 parts of water and then allowing it to float Completely immersed in the liquid for 2.5 minutes. Examination of the surface and cross-sections of the coagulated layer with the naked eye and with a magnifying glass shows that it is practically free of macropores; microscopic examination reveals a structure of interconnected micropores.

The coated material is then immersed in a 16 ° C water bath for 10 hours to remove practically everything Remove dimethylformamide.

Finally, the coated textile fabric is dried at 100.degree. After drying, it is microporous White polymer covering, about 0.38 mm thick and extremely permeable to water vapor. The topping can dyed, pinned and subjected to other manufacturing treatments, as is the case with leather and artificial leather can be applied. It can also be heated to 165 ° C for 5 minutes, which improves its abrasion resistance is improved.

The product has a water vapor permeability value of 6000. This value, which is also referred to as the leather permeability value, is named after the von K a η a g y and V i c k e r s in "Journal of the Leather Chemists Association", Volume 45, Pages 211 bis 242 of April 19, 1950, described method. The surface of the product is unusual smooth and uniform in appearance.

The product is suitable as a leather substitute for shoe upper leather, upholstery materials, handbags, Jackets, hats or hat linings.

Particularly important properties of the product "regarding Its usefulness as a shoe upper are: (a) Its wearing comfort, such as that Flexibility, the softness of the side of the fiber support that comes into contact with the foot, the ability to breathe and the ability to repel water when worn in the rain, (b) its external appearance including the absence of macropores through the entire thickness of the pavement, see above that the surface is subjected to manufacturing processing by roughening, pumicing, polishing, coloring and embossing without the risk of exposing ugly holes, and (c) his Durability including tear strength and resistance to bending and abrasion.

Example 2

A 16 ° / _o by weight solution of a mixture of 65 parts by weight polyurethane and 35 parts by weight of polyvinyl chloride in dimethylformamide is prepared according to Example. 1 The polyurethane elastomer may come from a different formulation and may therefore have somewhat different properties than that used in Example 1, although it is produced under conditions that are as similar as possible.

15 parts of the mixture of nonsolvent and solvent according to Example 1 (mixture of water and dimethylformamide in a ratio of 1: 4) are gradually added to 150 parts of the polymer solution with stirring. The amount of nonsolvent added to the solution is therefore 15/28 x 100 = 53.6% of that amount which leads to the appearance of the first signs of the formation of a colloidal dispersion. From here on, the procedure is the same as that of Example 1 with the following differences: (a) The layer of polymer solution on the nonwoven fabric is coagulated by immediately placing the coated fabric in a coagulating bath (ratio 90:10) at 50 for 5 minutes ⁰ C is immersed, and (b) the coated fabric is then immersed in running water at 20 ° C for 24 hours and then in boiling water for 1 hour. It is believed that treatment with boiling water makes the cellular structure more resistant to breakdown when oven-dried.

When dry, the product has good water vapor permeability and is suitable for same uses as the product of example 1.

B e i s ρ i e 1 3

Example 2 is used, but with the following differences:

(a) The amount of nonsolvent added to the solution is 22 / 88-100 = 78.6% of that of the amount required to form a colloidal dispersion.

(b) The ratio of dimethylformamide to water in the coagulating bath is 80:20, and the coated one Fabric is first coated side down on the bath surface for 30 seconds floated and then completely immersed in the bath for 5 minutes.

After drying, the product has a leather permeability value of 8300 and an edge abrasion resistance of 1000 cycles (using a No. 10 canvas for apparent roughening). After 5 minutes of heat treatment in the oven at 165 ° C. and cooling to room temperature, the product has an edge abrasion resistance of more than 2000 cycles and a Shildknecht flexural strength of more than 10 ₇ cycles. The applicability of the product is the same as that of the product described in Example 1.

Similar results are obtained when using a coagulating bath made from 70 parts of dimethylformamide and 30 parts of water.

To prepare a comparative sample is carried out according to Example 3, except that in place of the group consisting of 80 parts dimethylformamide and 20 parts of water coagulation bath a bath of 100 ° / ₀ water. The product obtained in this way has pores which are visible to the naked eye and scattered throughout the pore structure of the covering. These macropores severely limit the usability of the product because they impair the appearance, the manufacturing properties, the water-repellent properties and the durability of the product.

B e i s ρ i e 1 4

Example 2 is used, but with the following differences:

(a) No water or any other nonsolvent is added to the polymer solution.

(b) The ratio of dimethylformamide to water in the coagulating bath is 93: 7, and that of the coated one Fabric is allowed to float on the bath surface with the coated side down for 1 minute and then fully immersed for 9 minutes.

When dry, the product has sufficient water vapor permeability and is suitable for the same purposes as that of Example 1.

Example 5

Example 2 is used, but with the following differences:

(a) The weight ratio of polyurethane to polyvinyl chloride in the 16% strength polymer solution is 80:20.

(b) The amount of nonsolvent (water) added to the polymer solution is 72% of that Amount until the first appearance of signs of the formation of a colloidal dispersion would have to be added.

(c) The ratio of dimethylformamide to water in the coagulating bath is 80:20, and the coated one Fabric will float on the surface of the bath with the coated side down for 1 minute left and then immersed for 9 minutes.

(d) When the coated fabric is immersed in the water bath, the water temperature is 50 ° C. During the first 30 minutes of the water treatment, the bath is allowed to cool to room temperature the temperature of the water will drop by 1 ° C per minute.

The dried product has the same properties and applicability as that of example 3.

Example 6

A 16% solution of a mixture of 80 parts by weight of polyurethane and 20 parts by weight of polyvinyl chloride in dimethylformamide using the polyurethane elastomer described in Example 1 manufactured.

Then a carboxyvinyl polymer of high molecular weight is used as a hydrophobic thickener Polymer solution added in an amount of 1.5 percent by weight of the polymer solids content of the solution. After thorough distribution of the thickener in the solution, it has a viscosity of 400 P at 24 ° C.

The thickened solution is freed from trapped bubbles under reduced pressure in a vacuum chamber and filtered through gauze to remove any large particles.

The polymer solution to which no water or other liquid nonsolvent has been added, is then with the help of the doctor blade on one side of a porous non-woven fabric according to Example 1 bis applied to a wet layer thickness of 0.76 mm.

The viscous layer of the polymer solution on the non-woven textile quickly turns into a microporous one The structure coagulates by turning the coated material with the coated side down Floating on a mixture of 90% dimethylformamide and 10% water at 24 ° C for 30 seconds and then completely immersed in the liquid for 2 minutes.

Then, the coated fabric is dipped in a water bath at 50 ⁰ C, which is allowed to cool to room temperature over the next 30 minutes at a rate of 1 ° C per minute. The treatment in this water bath is continued for a further 24 hours, after which the coated fabric is immersed in boiling water for 1 hour.

The fabric is then dried in a heating zone at 100 ° C. After drying, the extremely vapor-permeable microporous covering can be colored, peened or be subjected to another manufacturing treatment for natural leather. The product has a Leather permeability value of 6000 and properties similar to the product according to Example 1.

Similar results are obtained if other substances are used as thickeners in Example 6, which form a viscous sol at relatively low concentrations, such as. B. the following: methyl cellulose, Sodium carboxymethyl cellulose, polyacrylic acid salts, polyvinyl alcohol or certain copolymers from methyl vinyl ether and maleic anhydride.

Example 7

Water is gradually added to a 22% solution of polyvinyl chloride resin in tetrahydrofuran. The amount of water is 91.2% of the amount that would be required for the first signs to appear occur for the conversion of the solution into an essentially colloidal polymer dispersion.

This polymer solution, modified with water, is applied to one side of a porous non-woven fabric with a doctor blade Textile according to Example 1 applied in a wet layer thickness of 0.76 mm.

The layer of polymer solution on the non-woven textile becomes a microporous structure coagulates by standing the coated fabric with the coated side down for 30 seconds on one Mixture of 90 parts of tetrahydrofuran and 10 parts of water is allowed to float at 24 ° C and then 5 minutes completely immersed in the liquid. The coated fabric is then mixed in for 5 minutes Immersed 10 parts of tetrahydrofuran and 90 parts of water at 24 ° C.

Finally, the coated material is dried at 100 ° C. in a heating zone. When drying is done first the tetrahydrofuran and only then the water practically completely expelled from the coagulated layer, whereby the breakdown of the cell structure is prevented. The dried, vapor-permeable Product is suitable for the manufacture of insoles for shoes.

You can also work according to the above example with the difference that the layer of the polymer solution applied to a polished glass plate and the resulting microporous polyvinyl chloride film after removed from the glass plate after bathing and drying.

Claims (5)

Patent claims: 1. Process for the production of vapor-permeable synthetic leather with microporous polymer 60 sat layer in the form of porous fiber substrates provided with microporous coatings or self-supporting microporous polymer films by applying a layer of a solution of a polymer in an organic solvent to the fiber substrate or an impermeable carrier, coagulating the polymer contained in the layer and removing the solvent from the layer by treating the coated carrier with a solvent-miscible liquid that does not dissolve the polymer and then drying, and in the case of turning an impermeable carrier, stripping the microporous layer therefrom, characterized in that solutions of such polymers are used which are derived from Point in time at which the solvent has been removed from the polymer layer, up to the point in time at which the nonsolvent has been removed from the polymer layer, a maximum elastic deformation strength comprise of at least 7 kg / cm ^2, and optionally wherein the polymer solution additionally a solvent miscible with the organic solvent non-solvent for the polymer in amounts of about 40 to 95 ° / ₀ of that amount which bring about the onset of conversion of the solution in a colloidal polymer dispersion and the coagulation of the polymer is carried out by treating the coated support with a mixture of an organic solvent for the polymer and a nonsolvent for the polymer which is at least partially miscible with the solvent at a weight ratio of solvent to nonsolvent of 10:90 to 95 : Performs 5. 2. The method according to claim 1, characterized in that the polymer solution before it on the carrier is applied, a thickener is added to increase its viscosity. 3. The method according to claim 1 or 2, characterized in that the predominant portion of the Polymerisats a polyurethane elastomer is used, which by reaction of a diisocyanate with a polyalkylene ether glycol containing reactive hydrogen atoms or Polyester with terminal hydroxyl groups to form a polyurethane prepolymer with terminal Isocyanate groups and further reaction of this prepolymer with a chain extender has been obtained in which two reactive hydrogen atoms to amino nitrogen atoms are bound. 4. The method according to claim 3, characterized in that a polymer is used which contains a smaller proportion of a polymer of vinyl chloride. 5. The method according to claim 1 to 4, characterized in that with a fiber base a nonwoven fabric impregnated with a polyurethane elastomer is used.