CS232497B1 - Method of hygienic refining of synthetic leather on polyurethan base - Google Patents

Abstract

The purpose of the present invention is to further approximate the existing synthetic leather to natural materials by adjusting organoleptic and hygienic properties. It is an adequate coloring of the back, an increase in the water vapor sorption of the back layer and the delivery of a fragrance reminiscent of natural leather. So far, most of these parameters have not been adjusted because of the cost or volume of equipment, time-consuming, costly raw materials or complexity of technology. According to the invention, a dye in an optional shade, a sorption agent and a characteristic natural leather aroma can be supplied in the back of the poromeric sheet material in a single short-term operation and cold on a low-cost manufacturing facility. It introduces into the material a solution or dispersion containing a penetration and sorption agent - a surfactant with good penetration ability; carrier polymeric binder - polyacrylate, polyurethane; non-migrating dye - metal complex, corresponding to the color of the cheek; optionally perfume and finally water. The material is then dried at 80 to 100 C. At the same time, the desired coloring of the back, durable perfuming treatment and increased sorption of the backing layer are achieved, while the other material parameters remain unchanged.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for the orgenoleptic and hygienic treatment of synthetic leather, used primarily for the manufacture of footwear uppers and approaching their use as natural leather.

Existing synthetic materials of this kind have two- or multi-layer construction. The top face layer is made of polyetherurethane, polyesterurethane or polyurethane and has a microporous structure.

On its outer surface there is an aesthetic and protective layer of the finish whose shade, appearance and touch are given by the present coloring agents, binders, additives and desen.

The backsheet is composed of a nonwoven web of most blended fibers, and is also permeated by microporous polyether urethane, polyester urethane or polyurethane urea.

Some of the synthetic leathers also contain a reinforcing interlayer, most commonly a mixed fiber fabric. The layers are bonded by lamination and / or gluing. The bonded formation is characterized by softness and flexibility, adequate mechanical strength and elongation in both longitudinal and transverse directions, water vapor permeability from back to face, water and dust impermeability in the opposite direction, and leather imitating the finish of the face. The basis weight of these bodies is in the range of 400 to 1200 gm, usually 500 to 600 gm ² .

While the microporous facing layer is colored to 7 to 8 shades, which are adequate to the colors of the subsequent finishes of the finished material, the coloring of the back is economically limited to a uniform neutral gray, gray-green or brown shade, or the back is not colored at all. Rarely is the backing layer dyed in a few other shades.

The known methods for coloring the backing layer can be summarized in two different processes: water and solvent. The aqueous process involves dyeing the polyurethane component of the synthetic leather in hot aqueous solutions or dispersions of dyes in anionic, chromium or generally mellitic dyes. These dyes bind to the substrate by chemical bonds and do not migrate to adjacent materials.

Both the microporous facing layer and the microporous portion of the polymeric binder embedded in the interspaces of the nonwoven fibrous backing layer are subjected to dyeing simultaneously. However, the coloring of the formation to a sufficient depth requires a nearly boiling dyeing bath, in the case of chrome dyes a hot chroming bath - a fixative and finally a system of scrubbing baths in which the material gets rid of excess dye. The main disadvantage of this method, however, is that it requires the establishment of a cleaning station in which the scrubbing water is freed of dye and returned for further use.

Polyurethanes, which are mostly a major component of modern synthetic leather, can also be dyed with disperse dye, soluble or dispersed metal complex dyes and selected vat dyes.

This method, known from dyeing elastomeric fibers from linear polyurethanes in boiling water baths, requires a very long contact time of the fiber with the bursting bath - 60 to 180 min - and is therefore not suitable for continuous production.

The solvent process involves coloring the polyurethane components in the mass, i.e. in the form of a solution in a non-aqueous solvent, especially in dimethylformamide. Dyeing is done with pigments and carbonblack.

The dyed polyurethane solution to which the nonwoven fibrous backing layer is bonded forms a microporous structure in the set shade by precipitation on the non-solvent segments of the fibers.

In particular, water is used as a non-solvent, so this process also requires a system of iodine baths. First, the polyurethane is precipitated and another bath is used to wash the solvent residue, which must then be regenerated from these baths, which is a costly process.

Production lines for both water and solvent dyeing processes take up considerable space and are very expensive. The coloring of the backing layer to a color matching the cheek color plays an important role in creating the appearance of natural leather, which has a considerable impact on their attractiveness and marketability in synthetic leather.

Of course, the requirements for a maximum level of hygienic properties of these materials, in particular sorption and water vapor permeability, remain. In the primary consumer assessment, however, the organoleptic properties are applied, that is to say, in addition to the adequate color of the reverse side, also suitable fragrances reminiscent of natural leather.

Synthetic waist blanks of plasticized polyvinyl chloride and other plastics where it is desirable to mask their specific odor or the unpleasant odor of additives such as plasticizers and blowing agents are subject to some of the following perfuming treatments:

- incorporation of perfume oils into the polymer together with a plasticizer,

- stretching through a perfumed bath,

- spraying of materials with diluted perfumes.

The first of these methods has the most lasting effect. Rubber mixtures can also be treated with it. However, the condition for using this process is that the perfume compositions can withstand the thermal stresses of the processing without decomposition and without serious loss, which is often problematic.

The second and third processes are less advantageous in terms of duration of action and, moreover, less economical due to the cost of the perfume compositions.

Natural leathers are sometimes subject to original odor correction to achieve a new product dimension to increase consumer interest. This treatment is carried out either by spraying or by applying perfume by injection technology to the pores of the leather, which is a relatively durable treatment, however, demanding on equipment.

Synthetic polyurethane leather has no specific odor that needs to be masked. The perfuming treatment of these materials can bring their organoleptic parameters closer to natural leather.

The above-mentioned disadvantages of the known processes for the organoleptic treatment of synthetic leather are eliminated by the organoleptic and hygienic treatment method according to the invention. SUMMARY OF THE INVENTION The backing layer of polyurethane-based synthetic leather is introduced into the pores at room temperature with an aqueous solution or dispersion containing a non-migrating dye, a penetration and sorption agent, a carrier binder and optionally a perfume. to 100 ° C.

The individual components are present in the following amounts and form:

10 to 20 wt. % non-migrating dye • - (III) solution or dispersion 5 to 20 wt. % suž. 5 to 10 wt. % penetration and sorption agent (I) solution 20 May eŽ 40 wt. % dry. 10 to 30 wt. % npsná polymerní colloidal solution or dispersion 25 to 40 wt. % dry. 0 to 3 wt. % perfume (ΙΪ) solution to 2 £ g OF? to 37 haotr.3 water;-

The solution, if any dispersion containing said reagents, panther upon controlled contact into the interstices of the backsheet. The next pass through a heated drying room evaporates more quantitatively! components, especially water.

Xa rolls of binder, an absorbent, a colorant and a scattered perfume composition are anchored to the cylinders of the inner surface of the interconnected mlcopores and entrained, without clogging the pores,

The inventive baking process can be supplied to the backing layer of a non-migrating dye-like non-migratory sheet material in a selectable shade, a pleasant leather scent, and a sorbent, in a single short-term and cold operation on an undemanding production facility.

If the backing layer is already dyed in the mass with pigments, it can be treated as easily as described above, but the resulting shade is additive. The main component of the impregnating solution with the above properties is water, so it is non-flammable.

Suitable binders are aqueous solutions or dispersions of polyacrylates, polyurethanes and mixtures thereof and copolymers, preferably colloidal polyethylene acrylate solutions of the polyesterurethane dispersion.

Anionic or nonionic surfactants, in particular alkoxylated alkyl sulfonates or phosphoric acid esters, can be used as microporous penetration enhancers and to increase the water vapor sorption capacity in the dry matter.

Among the coloring agents, non-migrating organic dyes with increased water and sweat resistance are preferred. These are in particular pallets of leather metal-complex dyes 1: 2 in liquid form, intermixable and dilutable with water and polar organic solvents such as alcohols, ketones, polyesters and the like.

These dyes color polyacrylate, polyurethane and other binders to almost any shade, while firmly anchoring them without significantly reducing their transparency.

The choice of fragrances, i.e. the quality of the perfume compositions, is not limited to the condition that they are not, readily volatile or decomposable at temperatures below 100 ° C. However, due to the use of poromeric materials, perfumes with the scent of natural leather are preferred to cosmetic, food, etc.

The solutions are prepared by mixing components 1, II, III, IV into water. The prepared mixtures do not have thixotropic behavior; their viscosity, measured in a Ferd crucible with an outlet of 004 mm, is at 25 ° C for only 10 to 15 s. The solutions have a pH of 6-8 and are stable.

•

The impregnating solution or dispersion can be dispensed in a variety of ways: by spraying the reverse side, pulling the reverse side over a layer of coarse-porous materials that are continuously replenished with the solution, by fractionated roller coating, and the like.

Advantageously, however, the solution is dispensed in a controllable and uniform manner into the backing layer by means of a constructionally simple machine, which consists essentially of two vertically mounted, motor driven rollers with a continuously variable speed in the range of 0.5 to 16 a. Min ^-1 and a pressure roller. , which can be approached to the lower cylinder in a horizontal direction. .

The upper roller has a smooth vulcanized rubber surface with a hardness of 70 ° Sh and serves to press the belt poromeric backing to the lower roller. The lower cylinder has a very indented (well-shaped) rubber surface and wads in the impregnation solution.

Using the side metal roller, the dose of solution that the lower roller is transferred into the material is regulated by appropriate squeezing.

The impregnated material emerges from a gap between the upper and lower cylinders of the dryer. After leaving the dryer, it is cooled on the surface of the cooling cylinder and coiled upside down.

The following examples serve to illustrate the synthetic leather process according to the invention.

Example l

Solution composition: wt. %

I - ethoxylated alkyl sulphonate enyαηΐ cocenate-ca 40 wt. % dry matter

XI - water-soluble polyethyl acrylate water concentrate - approx. % dry matter 18

XXX - dark brown metal-complex water concentrate - approx. % dry matter 12

IV - yeast solution in ethanol 20% 2 distilled water 60

Procedure: The solution was introduced using a laboratory model of the apparatus described above into the backsheet of a poromeric leather with a dark brown standard face finish at a material movement rate of 1.0 m / min in a quantity of 125 gm ^-2 . The treated poromeric material was dried in an oven at 80-100 ° C.

Properties:

mechanical - unchanged - 2 - 1 water vapor permeability - unchanged - 2.3 mg.cm .h —2 water vapor sorption from the back - increased from 3.08 to 5.20 mg.cm reverse color - uniform dark brown smell - strong, constant depth of backing - 0.4 to 0.6 mm, ie 1/4 to 1/2 thickness. reverse water resistance - dye non-extractable by water

Example 2.

The solution contained the same ingredients as in Example 1 and in the same amount, but a 1: 1 mixture of yellow and brown metal-complex dye was used instead of the dark brown dye, and the perfume used was a skin type of 10% solution in ethyl alcohol.

The solution was introduced in a controlled manner into the backsheet of the finished poromeric material with a light brown face finish, at a rate of 2.8 m / min, at a rate of 330 g.m. After drying, the material exhibited the following properties:

mechanical including flexibility water vapor permeability water vapor sorption reverse side color fragrance reverse saturation reverse color stability unchanged - despite addition of 28.9 gm solids unchanged - 2.19 mg.cm “ ² .h ^-1 increased from 3.12 to 4» 10 mg.cm “ ² uniform light brown distinctive, stable

1.2 mm - the whole thickness of the back in water and abrasion

Example 3

Solution composition:

I - ethoxylated alkyl sulfonate water concentrate - approx. 8%

II - water-soluble polyethylene acrylate water concentrate - approx. % dry matter

III - deep red-brown, metal-complex water concentrate - approx. % 18 denineralized water 47

Method:

The solution was entrapped in a light gray backing layer 1 and a wide pore of crude porous material - not yet coated, at a web speed of 4.0 m / min ^- at a rate of 75 gm using a metal screen roller.

After cleaning, the material was wound up and then underwent a complete standard face finish to a dark Servenbrown shade.

Properties:

reverse color - reddish-brown, corresponding to the face “2 water vapor sorption from the reverse - increased from 3.0 to 4.3 mg.ca other properties - unchanged

Example 4

Composition of dispersion:

AND phosphoric acid ester water concentrate - 23 ha. % dry matter 10 II - Polyesterurethane based on hexamethylenediisocyanate water dispersion - 37 wt. % dry matter 30 III - saffron yellow, metal complex water concentrate - 20 wt. % dry matter 16 IV - soft leather solution in ethyl alcohol 10% 3 Distilled water 41

Method:

The dispersion was applied by means of a roller with a surface of a plush textile-pipe layer _- 2 poromeric material with a bright yellow opaque finish in the amount of 155 gm. The treated material was dried in an oven.

Properties:

reverse coloring - yellow, corresponding to the color of the face of water vapor sorption from the reverse side - increased from 3.10 to 5.06 mg.m “^ aroma - distinctive, constant depth of saturation of the reverse side - 0.8 mm, ie 2/3 of the reverse thickness properties - unchanged

Claims (7)

SUBJECT OF THE INVENTION Process for the organoleptic and hygienic treatment of synthetic leather based on polyurethanes, characterized in that an aqueous solution or dispersion consisting of 0 to 20 wt. % of a solution or dispersion of a non-migrating dye containing 5 to 20 wt. % solids, 5 to 10 wt. % of a solution of penetration and absorbent composition containing 20 to 40 wt. % dry matter, 10 to 30 wt. % colloidal solution or dispersion of carrier polymeric binder containing 25 to 40 wt. % dry matter, 37 to 75 wt. % water and optionally up to 3 wt. The perfume solution is fixed in the pores by drying at 80-100 ° C. 2. Process for the organoleptic and hygienic treatment of synthetic leather according to claim 1, characterized in that the aqueous solution or dispersion is introduced in a controlled amount into the pores of the backing layer of the treated synthetic material at a speed of 0.5 to 16 m.min *. 3. The process for the organoleptic and hygienic treatment of synthetic leather according to claim 1, characterized in that, in the case of perfume application, the treatment is carried out as a last operation in the process of production and processing of synthetic leather. 4. The method according to claim 1, characterized in that the non-migrating dye is an organic dye resistant to water and sweat, preferably a leather metal-composite dye 1: 2. 5. Process according to claim 1, characterized in that the penetration and sorption agent is anionic or non-ionic surfactants, preferably alkoxylated alkylsulfonams or phosphoric acid esters. 6. A method according to claim 1, wherein the carrier polymeric binder is polyethylene acrylate in the form of a colloidal solution or polyesterurethane in the form of a dispersion. 7. Process according to claim 1, characterized in that the perfume is a special leather perfume, optionally diluted with a volatile solvent, preferably ethyl alcohol.