SU523644A3 - The method of obtaining artificial leather - Google Patents

Description

(54) METHOD FOR OBTAINING ARTIFICIAL SKIN

The invention relates to light industry, namely the production of artificial leather.

A method of producing artificial leather is known by applying a polymer solution (polyurethane) to a porous base moistened with a non-solvent, coagulating the polymer by passing a semi-finished product to a bath with a non-solvent or spraying a layer with a non-solvent, washing and then drying, while having a coating along with small pores. macropores and is characterized by a ribbed surface.

In order to obtain a polymer coating with a resistant microporous structure, it has been proposed to coagulate the polymer solution layer by contacting the substrate side opposite to the coating layer with a fibrous material moistened with a solvent. The solvent is dimethylformamide, and water serves as both a non-solvent and a wetting liquid. Mixtures of dimethylformamide and water can be used as a non-solvent and wetting liquid. It is also possible to use organic solvents which have the same ability to dissolve and be mixed with a solvent as DMF has. Such blends may contain from about 10 to about 90% water. Especially preferred

a mixture of water and dimethylformamide, containing 30% by weight first.

Only one water can be used as a non-solvent, although previously made

Attempts to apply water alone did not give satisfactory material. A particular advantage of the process envisioned by this invention is that the face layer is placed as on the surface of the base,

and inside it, and not in the form of a thin layer only on the surface of the base. This improves the appearance of the material and improves the physical properties of the latter, especially the peeling resistance.

A vapor permeable and capable of forming a polymeric face layer is deposited on the base when the substrate is treated with a wetting fluid due to the contact of the bottom surface of the base with a source of non-solvent (which may be identical with the wetting fluid), resulting in diffusion of the wetting fluid into the solution used for coating the upper surface of the base, and the deposition of the polymer in the form of a film. The coated and wetted base is applied to a porous carrier saturated with a wetting fluid and in contact with a source of additional wetting fluid or other non-solvent.

The base and the carrier are in contact with each other, whereby the wetting liquid diffuses through the base into the wet film and the elastomer is deposited.

A suitable porous carrier can be selected from a number of known materials, including wool felt, reinforced paper, polyurethane or other polymeric foams, and so on.

Some bases suitable for making imitation leathers can be very porous and allow molecular diffusion of the non-solvent at such a rate that the polymer will deposit too quickly, resulting in macropores. Other bases may be somewhat less porous. With bases of the first type, carriers can be used that do not very quickly transfer the non-solvent, while using less porous bases, carriers are used that hold the non-solvent less firmly.

Preferred polymers in accordance with this invention are polyurethanes.

Polyvinyl chloride is used with polyurethanes.

In the manufacture of elastic material for the top of shoes or other similar material from a mixture of polyurethane and polyvinyl chloride, it is often desirable to use a larger amount (more than 50%) of the first and a smaller amount (less than 50%) of the second. However, suitable films are prepared in accordance with the present invention with a greater proportion (at least 51% by weight) of polyvinyl chloride.

Stabilizers, colorants, plasticizers, etc. are added to the elastomer solution to improve the properties or appearance of the final product.

Nonwoven fabric, fabric, knitwear, polyurethane foam are used as the basis, which fill the polyurethane with a porous structure obtained by the coagulation method. Complex basics are also being prepared. Preferred complex bases are three-component (foam-filler) bases. They are prepared by crosslinking with foam before forming the main web. The upper batt consists of two types of fibers, one of which is thermoplastic and is stitched to the main canvas to form a complex web. Complex canvas is subjected to pressing treatment at elevated temperatures. Typically, such treatment is performed at a temperature in the range of from about 121 to 190 ° C and a pressure in the range from 0.035 to 7 kg / cm for a period of from 20 seconds to 5 minutes. Then the compressed composite canvas is impregnated with a solution of an elastomeric filler, preferably a polyurethane elastomer, with the result that the filler is deposited inside the web. This can be done by immersing the scrim in a liquid that is miscible with the applied solvent, but not a solvent elastomer.

Any of the elastomers described above may be used as suitable for the formation of a face layer.

After that, a complex base with an elastomeric filler deposited in it can be dried, softened mechanically and subjected to heat treatment at a temperature in the range of about 149-176 ° C and a pressure of 0.14-0.36 kg / cm for sec.

The resulting base is moistened with a non-solvent and coated with a solution of polyurethane. The coating can be applied in one or several strokes. Fillers, stabilizers and other special additives are introduced into the polyurethane solution.

The following examples are provided to clarify the invention.

Example 1. By air laminating fibers 100% from nylon-66 is obtained

it is combed and combined with a 0.63 mm thick sheet of polyurethane foam.

Then, the resulting canvas is in contact with the fiber side up with a freshly prepared web as a mixture (2: .1) of nylon.

and polyester fiber. The canvas is again passed through the shuttleless rapier weaving machine with the fiber side upward to form a complex canvas.

The resulting composite canvas is passed through a cylindrical press with a residence time of 1 minute and a pressure of 0.35 kg / cm heated on the fiber side at a temperature of 157 ° C to bond the nylon fiber at selected points. Then complex canvas

impregnated with a solution of polyurethane elastomer in dimethylformamide containing 15% solids, and passed through a roller in such a way that the total weight gain is increased to 500%.

The elastomer used was the reaction product of toluene diisocyanate with diethylene glycol ether and adipic acid, which resulted in a prepolymer. Chain last lengthened when exposed

He, L-methylenedianyl. Thereafter, the impregnated composite web is passed through a water bath to deposit an elastomer therein. Water on Vania is equipped with rollers to move the material. The latter is washed with water by passing it through a second water bath, also equipped with rollers, and dried.

The resulting dry base is immersed in a nu-bath. The material wetted with water is squeezed out on rollers to obtain a base that does not have a surface liquid film. A solution containing 25% by weight of a polyurethane elastomer in dimethylformamide is applied onto the surface of the base with a squeegee.

forming a film about 0.76 mm thick. The coated base is placed on the bottom surface on an endless felt belt saturated with water. Almost immediately, a polymer film began to deposit on the surface of the substrate. A few minutes later formed

Lenka sufficient thickness. The base with the foil passes through the squeezing rolls into the military tank. Washed material after drying Rygoda as leatherette. The elastomer solution used to form the face layer gave, during the reaction, 74 parts by weight of adipate to an ethylene glycol field with terminal and hydroxyl groups that had a molecular weight of about 2000 and a hydroxyl content of 1.5%. Reaction from 19.75 wt. Part p, p-methylene diphenyl diisocyanate in anhydrous dimethylformamide is carried out at a temperature of 100-PO C for 1 hour.

The chain is extended by reacting the prepolymer at 35 ° C for 1 hour with 7.1 parts by weight of n, (7) -methylene dianiline in the form of a 30% solution in dimethylformamide. The resulting solution contained about 25% by weight elastomer.

Example 2. Polypropylene film is coated with a squeegee with a film with a thickness of 0.10 mm of the following composition, weight. h .: Polyurethane elastomer of example 1 (25% solution in dimethylformamide) 100

Dimethylformamide 25

Azo dye 0.15

Technical objective16

Colloidal silica 1.5

A complex base, identical to that used in Example 1, is immersed in water and squeezed out on a roller mill. A polyurethane layer is applied to the total amount of water added to 60%.

A polypropylene film is applied to the wet substrate and passed through rollers into water to deposit the elastomer. The propylene film is then removed.

The resulting material is pressed so that it remains wet, but does not have a film of wetting liquid on the surface. A film with a thickness of 0.89 mm of the same composition that was used to prepare the base layer of the first layer was applied to the surface already bearing the face layer. The coated composite canvas is applied with the coated side up onto polyurethane foam with open pores and saturated with water, and is kept for 10 minutes until the elastomer is deposited as a thin film. Then the material is washed with water and dried. This soft material is similar to skin, both in appearance and touch. The face layer about 0.25 mm thick had no macropests in cross section. Its surface is smooth

and attractive. Bending resistance 4000 cycles. Vapor permeability is 135 mg / cm per 24 hours.

The same results were obtained when applying the wool felt as a carrier.

instead of polyurethane foam. Both materials are suitable for making shoe upper.

Example 3. The procedure of Example 2 is repeated, except that a mixture (70:30 by weight) of dimethylformamide and water is used as a wetting liquid and a non-solvent. The properties of the material obtained are the same as the material of example 2.

Example 4. Material similar to the material of Example 2 was prepared by repeating.

the procedure described in Example 2, except that the solution used to produce a film with a thickness of 0.89 mm is converted into a colloidal dispersion by adding water before casting the wet film on the base.

Claims (1)

Invention Formula The method of obtaining artificial leather by applying a polyurethane solution or its mixture with polyvinyl chloride to the non-solvent moistened base, coagulation of the polymer in the layer, washing and subsequent essence, characterized in that in order to obtain a polymer coating with a fine microporous structure, as well as to simplify the technological of the process, the coagulation of the polymer in the layer is carried out by contacting the substrate side opposite to the coating layer with a fibrous material moistened with a non-solvent.