DE1779417A1 - Multi-layer synthetic leather and process for its manufacture - Google Patents

Description

PATENTANWXL ' DR. E. WIEGAND DIPL-ING. W. NIEMANN 1779417 DR. M. KÖHLER DIPL-ING. C. GERNHARDT MÖNCHEN HAMBURG

TELEPHONE, 55547 «8000 MONCH EN 15, AUGUST 9, 1968

TELEGRAMS. KARPATENT NUSSBAUMSTRASSE 10 "

W. 13 810/68 7 / Loe

The Toy ο Rubber Industry Co., Ltd. Osaka (Japan)

Multi-layer synthetic leather and process for its manufacture. ·

The invention relates to a multilayer synthetic leather and an improved process for its manufacture, wherein a porous layer of coagulated Polymers on a surface of a sheet or a Forms a web having a structure in which a polymer is in the porous state between fibers in a fibrous material is coagulated.

The object of the invention is in particular to create a method for producing synthetic leather with high adhesive strength or adhesive strength between the layers

Another object of the invention is to provide a soft synthetic leather with excellent air and water resistance Moisture permeability by forming a layer of porous polymer that has a more uniform porous structure

having. ...

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Studies dealing with synthetic loading " have already been carried out in large numbers, and various processes for its preparation are known. In Recently, the manufacture of synthetic leather by a wet process has been attracting attention because it has been recognized that this is suitable to "when making a synthetic Leather one. common film formation process for polymers

P "apply, in which a polymer solution with one the polymer non-solvent solvent, which is miscible with the solvent of the polymer, is treated so that the porous Structure is formed. As a result of the need to have a resemblance to the macrostructure of natural leather achieve or for reasons of strength or other physiial properties in synthetic leather Structure of the synthetic leather by the wet process is generally composed of a multilayer structure composed of a fibrous base layer and a porous layer of the coagulated polymer.

en
Thus, in the known method of manufacture

of synthetic leather after the wet process fiber materials, such as fabrics or non-woven textiles (non-woven fabrics) impregnated with a polymer solution, then in a liquid which does not dissolve the polymer and which is mixed with the solvent of the Polymer is miscible, immersed to the solvent

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to extract and to form the fiber base. Below • For the sake of simplicity, the liquid is called "nonsolvent" designated. After the polymer solution has been applied to the fiber base, it is re-introduced into the Non-solvent immersed to the coating applied Coagulate polymer layer in a porous structure. In the known method, the polymer solution is immediate applied as a coating to the fiber base without any special pretreatment of the base taking place, and coagulated in the nonsolvent so that the adhesion between the base and the coagulated porous polymer layer is unsatisfactory and with prolonged use, especially with frequent bending stress a separation between the layers was often observed. Furthermore, in the known method, the Fiber base as a coating applied polymer solution only generally by the action of the nonsolvent coagulated from the surface of the coated layer, "

so that the formation of a uniform fine porous Shift is difficult.

According to the invention these difficulties of the known method are overcome and soft synthetic ones Get leathers that contain a polymer layer composed of a uniform foam structure, a high Have adhesive strength between the layers and have excellent air and moisture permeability.

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According to the invention, the multilayer structure is produced. made by carrying out a special pretreatment of the Paser base, in which the polymer in the porous state is coagulated, whereupon a coagulated polymer of a polyurethane elastomer in the porous state this pretreated fiber base is formed.

The inventive method for producing a multilayer synthetic leather consists in the fact that, as the first stage, a fiber material with a polyurethane elastomer containing polymer solution, then impregnated with a liquid which is mixed with the solvent of the polymer is miscible and is a nonsolvent for the polymer, treats the polymer in a porous structure to coagulate and obtain a fiber base than second stage an aqueous solution containing at least one component from the group of water, solvents for the polyurethane elastomer and surface-active agents, applies to this fiber base and, as a third stage, one a polyurethane elastomer-containing polymer solution applied to the pretreated fiber base as a coating, whereupon then the polymer is coagulated into a porous structure by treatment with the nonsolvent. (The liquid, which is miscible with the solvent of the polymer and is a nonsolvent for the polymer simply referred to as nonsolvent.)

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According to the invention, polymers containing a polyurethane elastomer as the main component can be used, because these not only have a chemical similarity to the collagen fibers that make up natural leather, but also resemble natural leather in appearance as coagulated polymers.

The polyurethane elastomers can be prepared by reacting an end "permanent hydroxyl group-containing linear polymers' λ an organic diisocyanate and optionally a chain extender via the terminal isocyanate groups-containing .Vorpolymeren · or in one step without the application,

(in bulk) prepolymers and in a solvent or in the block without a solvent.

The terminal hydroxyl-containing linear polymers are, for example, polyester glycols obtained by reacting dicarboxylic acids with an excess number of moles of glycols, polyalkylene ether glycols obtained by ring-opening polymerization of cyclic ethers, and poly-acetal glycols obtained by polymerizing Organic diisocyanates that can be used include, for example, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, m-phenylene diisocyanate, biphenylene-4,4'-diisocyanate, methylene-bis (4-phenyl isocyanate ), 4-Ghlor-1,3-phenylene, naphthalene-1 _s 5-diisocyanate, tetramethylene diisocyanate-1,4, decamethylene diisocyanate 1,10-, cyclohexylene-1,4-diisocyanate, diisocyanate, and similar compounds 2etrahydrοnaphthalin- are used to react with the polymers,

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As chain lengthening agents, ζ.B. Water, ethylene glycol, Diethylene glycol, propylene glycol, hydrazine, ethylenediamine, Propylenediamine, tetramethylenediamine, xylylenediamine and the like Connections are used. Desires also know others Polymers, for example polyamides, polyvinyl acetate, polyvinyl chloride, cellulose acetate, polyacrylonitrile, acrylonitrile-vinyl chloride copolymers, AcrylonitaiL-Butadiene-Styrene Terpolymers and like soluble polymers can be added to the polyurethane elastomers.

In such cases it is advantageous if the polyurethane elastomer at least 50% by weight, based on the total number of polymers, in terms of the properties required for a permeable sheet material.

These polymers are in a solvent such as acetone, Tetrahydrofuran, acetonitrile, dimethyl sulfosyd, N, If-dimethylformamide, .Ν, Ν-dimethylacetamide, Tetramethylurea or mixtures thereof are dissolved and then used with the resulting solution impregnates the fiber material.

Fiber materials which can be used in the context of the invention are woven, knitted and non-woven Textiles. Suitable fiber materials are also roughened or napped woven or knitted fabrics and fiber mats.

In the impregnation process of the fiber material with the polymer solution, if the viscosity of the polymer

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solution is relatively low, the impregnation in be carried out in an adequate manner by simply immersing the fiber material in a bath of the polymer solution, and, if the viscosity is above 1 <r cPS, a more stringent impregnation process, for example roller impregnation, can be used to adequately impregnate the inner parts *

The impregnated in this way with the polymer solution fibrous material is then treated with a liquid like is miscible with the solvent of the polymer solution and represents a non-solvent for the polymer, for example, water, lower alcohols such as methanol or ethanol, ethylene glycol or glycerine to to coagulate the polymer in a porous state. As the treatment method with the nonsolvent, an immersion method in a bath of the nonsolvent is generally effective. If desired, the nonsolvent can also be applied in the mist state by a sprayer or shower, or it can be applied in the vapor state.

Thus, on the fibrous base material obtained in the above first stage ■ water or an aqueous solution, the at least one component of the group consisting of solvents for the polyurethane elastomers and surface-active agents Contains agent, applied.

The water or the aqueous solution can be sprayed onto the surface of the fibrous base or a shower can be applied or the fibrous base «

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location can be made up of water or in a steam atmosphere alone
aqueous solution are allowed to stand. The most effective method is to immerse the fiber base in water or; the, aqueous solution and subsequent squeezing. The amount
of the water or that applied to the fiber base
aqueous solution is favorably between 20 and 100 wt .- ^ *
based on the fibrous base. Palis it is less than 20 wt ■ i, - # is, according to the invention desired effect is not obtained · in sufficient degree, and if it is above. Is 100% by weight, the polymer solution drawn up in the third stage quickly becomes in the interface between solution and
fibrous basis coagulated so that the objectives of the He '{invention may not be reached *

In case of application of an aqueous solution, the nitrile of the urethane elastomers, such as tetrahydrofuran, Ac'eto- i contains a solution B "· i medium, N, N-dimethylformamide, Ν, Ν-diethylformamide and K, H-dimethylacetamide, has the The concentration of the solvent should be less than 90? 4. If 'an aqueous solution with
a high concentration above 90 f> is used
the polymer film coagulated on the fibrous base
often resolved and the eoagulation speed of the on; the fiber-containing base in the third stage drawn) polymer solution is lowered, so that the objects of the invention are not achieved to a sufficient extent.

The surface active agents dissolved in the water or an aqueous solution of a solvent for the urethane elastomer ";

Means are ζ "Β. anionic surfactants such as fatty acid salts and amine salts, cationic surfactants such as amine salts, nonionic surfactants such as polyoxyalkylenes and amphoteric surfactants. The amount of the surfactant is less than 1 wt _# - # of the aqueous solution

According to the invention, the adhesive strength between the fibrous base obtained in the first stage and the coagulated porous polymer layer obtained in the third stage is remarkably improved by the second stage.

The reason can be assumed that the contact angle to the polymer solution drawn up in the third stage is caused by the or the water or aqueous solution applied in the second stage is lowered, so that the so-called moisture (wetness) is improved, or that the coagulation of the'aufzugenen Polymer solution runs slowly in the interface.

Actually, however, the reason why goals of the invention are achieved stage by the second, until now not known λ, as the mechanism for "Koaguliererscheinung of polymer solutions is not sufficiently clear.

However, according to the invention, the adhesive strength is between all of the layers are remarkably improved, and the polymer layer formed in the third stage becomes a unitary one Soil structure coagulated *

After the second stage, a polymer solution, which contains as the main constituent a Polyurethanelaatomeres, on the fiber-containing base and coated with a non-tufted

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agent for the agulation of the polymer in the porous state as third stage treated. The polymer solution used in the third stage is suitably the same as in the first Level due to miscibility. However, depending on the properties desired in the product, the composition slightly different from the one used in the first stage. Application rollers, calendering rollers or coating processes be performed. If the viscosity of the polymer solution. is low, a common drawing process can be, for example a spray process can be used »

Treatment with a nonsolvent for eoagulation the coated polymer solution layer can be carried out in the same manner as in the first stage.

The foam structure of the soagulated polymer layer is essential for the handle, the feel and the physical properties of the product. In general, the &> agulierung <j _he polymer solution is affected in the liichtlösungsmittel the foam structure through the Koagulierbedingungen in Pall in "game, the kind of the polymer and solvent, the concentration of the solution, the composition bades of coagulated and the temperature of the coagulating bath. For example, the use of homogeneous solutions, the addition of a ^ _,? Surface-active agents for this purpose, use of heterogeneous polymer solutions with the addition of small amounts of a nonsolvent, or use of a solution with the addition of insoluble ones

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Polymer particles, short fibers, leather powders or anorganic

en

see particles, such as magnesium carbonate, making the foam structure remarkable different from each other, even if the coagulation

respectively
lation takes place under the same respective conditions. According to the invention, synthetic leathers of a suitable structure can be obtained by suitable choice of these factors which have a direct influence on the foam structure of the coagulated polymer layer in the first or third stage.

The following example serves to further explain the Λ Invention »

example

5 kg (5 mol) of a polypropylene glycol with a molecular weight of 1000 were ^{heated to 50 °} C., and then 2.5 kg (-10 mol) of molten diphenylmethane-4,4'-diisocyanate were added 80 ¹ C carried out for 1.5 hours under dry air with sufficient stirring. An ITorpolymer containing terminal isocyanate groups and having 5 _f 3 # free isocyanate groups was obtained. After cooling the product to 30 ⁰ C,

i added 11.2 kg N,! ^ dimethylformamide (DMP) was added and a "·

uniformly dissolved, after which it was then cooled to 22 ° C.

To this, a solution which had been obtained by dissolving 250 g (4.2 mol) of ethylenediamine and 39 g (0.3 mol) of di-n-butylamine in 3.0 kg of DMP was added over a period of 10 minutes, while stirring and was cooled with water, then were added 8.0 kg DMP, so that the solution 25 f> of the poly ·· · propylenäther- "Urethanharnstoffelastomeren contained and a viscosity at 11 000 cpe had 3QK.

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One made by needles one on one side of fluffy j

Cotton flannel of 180 g / m and a fabric of 200 g / m from S.

fibers

Nylo.nstapel- from 3 denier χ 51mm "existing stack by means of)

fiber material obtained from the fabric side of a conifer

was used· · . |

The fiber material was mixed with a $ 12 solution of the * |

• i '

Polyurethane elastomers impregnated in DMP, then in water from · j

Immersed in 45 ^° C. for 3 hours, washed with water and cleaned.

dries · This preserves the fibrous base · \.

On the fibrous base was water or an aqueous solution of DMP or a surfactant Emuigen 220 (a non-tonic surfactant the Kao Soap Κ »Κ ·) applied in the quantities listed in the following table» The produced in the following way * » put polymer solution was on this pretreated fibrous |

Base raised · ■. I.

) To the above 25? »Solution of the polypropylene ether

Urethane urea elastomers in DMP were polyvinyl chloride in V

an amount of 10 parts by weight to 100 parts of the polyurethane /

· added elastomeric This mixed solution was ι calcium carbonate powder in an amount of 25 percent by "parts by 100 parts of poly urethane elastomer ·· added and uniformly by means of a

Dispersed homogenizer. The defoaming of the mixed solution y

was carried out under reduced pressure. The solution was y mm onto the pretreated fibrous vprstehende basis in a thickness of 1.5 by means of a doctor blade on Eye- »subjected · The coated product was dissolved in water of 35 ¹ G while V

. ) 109841/0559 [

Immersed for 5 minutes and then placed in warm water of 65 ⁰ C and left to stand for 10 minutes * It was then 10 times between rollers under a linear

. 2

Pressure of 4 kg / cm pressed and dried at 100 to 105 ⁰ C.

The resulting multilayer synthetic leather .hatte a structure in which a uniformly coagulated porous polymer layer was layered on the fibrous base and it had a flexible handle.

The moisture permeability of the leather was 1460 (g / 24 hrp m ² ) and the Garley stiffness was 2910 (mg). The relationship between the amount of water or an aqueous solution of DME ¹ or Emuigen 220 applied to the fibrous base and the adhesive strength is shown in the following table:

Application of water or
aqueous solution lot Separation strength no 0 0.2 kg / cm water 34 Destruction of the structure 25 $ aqueous DMP solution 33 Il 50 # aqueous DMF solution 36 Il Qi 05 $ aqueous emulsifying
solution 30th It aqueous solution of 25 #
DMP and 0.05 * emuigen 30th It

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Footnotes;

The amount used is given in wt _# - $ based on the dry fibrous base.
The structure is destroyed when the adhesive strength of the sample is higher than the separation strength between the fibrous base and the porous polymer layer coagulated on it, so that it indicates the destruction of the inner layer of the sample.

According to the invention, a multi-layer synthetic leather with a high adhesive strength between the layers, excellent flexibility and excellent moisture « get permeability.

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Claims (11)

Claims (1 V / process for the production of a multilayer synthetic leather, characterized in that a fiber material is impregnated as a first step with a polymer solution containing a polyurethane elastomer as the main component, then with a liquid designated as a nonsolvent which is % miscible with the solvent of the polymer solution and is a nonsolvent for the polymer, treated with eoagulation of the polymer into a porous structure to obtain a fiber base, as a second stage water or an aqueous solution containing solvents for the polyurethane elastomer and / or surfactants is applied to the fiber base and as a third step, a polymer solution containing a polyurethane elastomer as a main component is applied to the pretreated fiber base as a coating and then the polymer is coagulated to form a porous structure by treatment with the nonsolvent. 2) Method according to claim 1, characterized in that the main component containing a polyurethane elastomer Polymer solution more than 5o wt .-%, based on the contains all polymers, polyurethane elastomers and optionally polyamides, polyvinyl acetate, polyvinyl chloride, Cellulose acetate, polyacrylonitrile, acrylonitrile-vinyl chloride copolymers c ".?. r acrylonitrile-bitadiene-styrene terpolymers as Contains polymers. 109841/0659 3) Method according to claim 1 or 2, characterized in that the solvent as the main component Polymer solution containing polyurethane elastomers acetone, Tetrahydrofuran, acetonitrile, dimethyl sulfoxide, Ν, ϊϊ-dimethyl " formamide, ϊϊ, Ν-dimethylacetamide, tetramethylurea or mixtures of which is used. In to 3, characterized W 4) A method according to any one of claims 1 ", that are used as fibrous material woven, knitted or non-woven textiles. 5) Method according to one of claims 1 to 4, thereby characterized that water, methanol, Ethanol, ethylene glycol or glycerin is used. • 6) Method according to one of claims 1 to 51 thereby characterized in that water or an aqueous solution, the solvent for the polyurethane elastomer and / or surface-active Contains funds to the. fiber base obtained in the first stage in an amount of 2o to 1oo wt. based on the basis. 7) The method according to claim 6, characterized in that that the aqueous solution is less than 9o wt .-% of the solvent for the polyurethane elastomer tetrahydrofuran, acetonitrile, Ν, Ν-dimethylformamide, Ν, Ν-diethylformamide or N, N-dimethylacetamide contains. 109841 / HS59 • 8. The method according to claim 6, characterized in that the aqueous solution contains less than 1 % by weight of at least one anionic surfactant, a cationic surfactant, a nonionic surfactant or an amphoteric surfactant. 9) Method according to claim 6, characterized in that the aqueous solution is less than 9o wt .-% of the solvent for the polyurethane elastomer tetrahydrofuran, acetonitrile, Ν, Ν-dimethylformamide, Ν, Ν-diethylformamide or N, N-dimethy! Acetamide and less than 1 wt. -ψο at least one anionic surfactant, cationic surfactant, nonionic surfactant or amphoteric surfactant contains · 10) Method according to one of claims 1 to 9 »thereby characterized in that as the main component of the polyurethane elastomer containing polymer solution {particles such as short fibers, leather powder or magnesium or calcium carbonate, contains. 11) Multi-layer synthetic leather obtained according to any one of claims 1 to "to. 109841/0559