DE967403C - Process for the manufacture of a breathable synthetic leather from polyvinyl chloride - Google Patents

Description

ISSUED NOVEMBER 7, 1957

CLASS 8 1 GROUP INTERNAT. CLASS D 06η

Di34i7lVc / 8l

Dr. Karl Stiehl, Hanau / M.,

It is known that by coating fabrics, nonwovens or the like. With plasticizer and pigment-containing polyvinyl chloride pastes and subsequent gelling and embossing artificial leather-like Products can be manufactured. Such artificial leather can also be used in the form of linerless foils be made. Compared to natural leather, the same have the disadvantage that they are neither water vapor nor air permeable. Because of this, these artificial leathers are made for the Manufacture of articles of clothing not very suitable.

There are already several ways of making breathable synthetic leather based on polyvinyl chloride have been labeled. It has been proposed to perforate the finished synthetic leather. this can be made, for example, with the help of needle rollers or embossing rollers, which have needle-like extensions on the raised points in order to thereby achieving a piercing of the artificial leather. Furthermore, a method has become known in which a breakthrough of the synthetic leather web by means of electrical sparks in the electrical High voltage field is made, whereby a fine and uniform pore formation is achieved can be. The disadvantages of these known methods are mainly to be seen in the fact that such mechanically perforated synthetic leather panels not only air and water vapor, but also Allow water to pass through in liquid form without further ado. There is also the risk that both through the mechanical and through the perforation generated in the high-voltage electrical field the strength values of the carrier material

708-751 / 4

To suffer. Also the surface image, on that of artificial leather Great importance is attached to suffering from this mechanical treatment. One has therefore endeavors to remedy these disadvantages by abandoning the well-known use of Propellants makes use of the production of fine pores. Furthermore, one tried to get through Mixing in liquids with a suitable boiling point, which during the gelation process ίο evaporate, creating pores. Although this process results in porous, for air and layers permeable to water vapor. However, these will take place during the subsequent The embossing process is so strongly compressed that the desired Effect of water vapor and air permeability is not achieved satisfactorily. Also through that Mixing in of water-soluble substances or of substances that result from subsequent treatment Can be made water-soluble, to the polyvinyl chloride spreading pastes and leaching out Attempts have been made to make a porous material of these water-soluble components after the gelling process to obtain. This last-mentioned procedure could not prevail in practice because it was too is cumbersome and expensive. The mechanical nature of the aforementioned Treatment process very spongy polyvinyl chloride layer left something to be desired. Pastes made from powdered polyvinyl chloride were also used in the past and only when they were heated gelling plasticizers mixed with inorganic fillers, which are insoluble in the plasticizers Contain liquid, in particular water, in mechanically bound form; also has new, pasty, aqueous dispersions based on polyvinyl chloride or its copolymers a certain grain size (1 to 30 μ), which is used to make porous, breathable Synthetic leather can be used.

Finally, it is known, aqueous emulsions of rubber, rubber-like substances or of synthetic resins, which contain certain amounts of soluble starch or glue, for impregnation of fiber masses to be used. This process is therefore limited to working in an aqueous one Medium and did not suggest what the properties of anhydrous pastes would be which swellable high molecular weight substances have been incorporated.

It has now been found, surprisingly, that by mixing in water or organic Solvents swellable high molecular weight 'substances such. B. Strength, in the amount of preferably 5. to 200/0, to one of the usual polyvinyl chloride, Plasticizer and pigment paint containing coating slip and some water in which a part or the entire amount of starch is swollen, a spread for a suitable urite layer can get; the spread is very porous after gelling, the porosity in the subsequent Embossing, which can be carried out in the previously customary procedure, received remain. Instead of starch, other swellable high molecular weight substances, preferably such, can also be used hydrophilic in nature, such as B. viscose, casein, gelatin, agar-agar, polyvinyl alcohol, polyamides or cellulose ethers or cellulose esters can also be used. Also polystyrene or other polyvinyl compounds, those in suitable solutions or swelling agents, expediently those whose boiling point is below the gelation temperature of the polyvinyl chloride, is dissolved or swollen, can be used for the purpose of the invention. The incorporation of this swellable High molecular weight substances is expediently carried out in such a way that these initially in the Swelling agents, i.e. in water or organic solvents, optionally with additives an emulsifying agent, can be made into a paste with a high viscosity. This paste is made using a high-speed stirrer in a polyvinyl chloride compound containing plasticizer and color suitable for the manufacture of artificial leather incorporated.

The effect that can be achieved with the aid of these high molecular weight substances can be increased by adding generally known propellants if one wants to achieve particularly high air permeability of the artificial leather. Propellants are to be understood as meaning all substances that ^{decompose between 20 and 200 c} with formation of gas and leave no residues that damage the polyvinyl chloride compound or are physiologically imperfect. In addition, ammonium carbonate, ammonium bicarbonate, iron oxalate, ethylmalonic acid, 0- and m-benzoic acid, o- and m-azoxybenzoic acid, diaminodiphenylamine, hydrabenzene, citric acid, and also per compounds such as benzoyl peroxide, percarbamide, optionally in the presence of activators, may be mentioned. These substances can be used in amounts of ο to 10 %, preferably 0.2 to 50/0. They are either dissolved in a little water or finely powdered and added to the coating slip. Depending on the decomposition point of the coating agent, it is then necessary to carry out the drying and gelling process at the temperature corresponding to this decomposition point.

On the other hand, the hydrophilic character of the synthetic leather material can be reduced by adding hydrophilic capillary-active fillers to the poly- no vinyl chloride-containing coating material, such as, for. B. of cellulose fibers (cotton, rayon, rayon flakes, paper flour, wood flour, cork flour) or of protein-containing products (leather flour, leather powder or flakes from animal hair), where- ¹¹ S can be varied greatly by the water vapor permeability. The addition or complete replacement of the plasticizers commonly used in polyvinyl chloride pastes by those of a hydrophilic nature has an effect in the same way, provided that they are compatible with polyvinyl chloride, e.g. B. such as castor oil fatty acid derivatives.

Examples

i. A cotton fabric (cross body) of about 27og / qm is made with a mass of the following

Composition coated in a thickness of around 35og / qm :

48.90 / 0 polyvinyl chloride,

31.50 / 0 dioctyl phthalate,

9.8 0/0 pigment color,

0.70 / 0 leather flour,

6.20 / 0 thickness,

2.90 / 0 ammonium carbonate.

to ΐοο, οθ / o

The preparation of this coating composition is carried out in such a way that polyvinyl chloride, plasticizer and pigment color are rubbed together in the usual way and easily gelled. The other components are mixed in as usual in a suitable mixing device. This allows the spreadability of the paste to be varied within certain limits. The ammonium carbonate is dissolved in a little water and incorporated as the last component of the coating mass.

The so coated fabric happens within 4 to 6 minutes at a temperature of about 170 ⁰ a heating duct. Immediately after leaving the heating channel, the same is provided with a leather-like grain by embossing with an embossing device customary for polyvinyl chloride synthetic leather.

The artificial leather material produced in this way shows a water vapor permeability of about 200 to 240 mg / 1000 mm ² within 24 hours compared to absolutely dry air. At an excess pressure of 50 cm water column and 100 cm ² surface, the air permeability is about 600 to 700 ecm within 1 minute.

2. A cotton fabric (cross body) of about 3oog / qm weight is made with a mass of the following Composition with a thickness of 4oog / qm coated:

50.00 / 0 polyvinyl chloride,
21.0 0/0 dioctyl phthalate,

8.00 / 0 dibutyl phthalate,
11, ο 0/0 pigment paint,
0.80 / 0 leather dust,
0.20 / 0 paper flour,
6, ο o / o strength,

1.50 / 0 ammonium carbonate,
1.50 / 0 ammonium percarbonate.

100.0 o / o

In the usual way, the polyvinyl chloride, plasticizers and pigment paint rubbed together and the mass slightly gelled. Then the leather dust and the paper flour and Finally, the other 'additives are incorporated in a kneading device.

The coated fabric passes with this mass within 4 to 6 minutes at a temperature of about 170 ⁰ a heating duct, immediately after leaving the heating channel a leather-like grain pattern is produced by embossing with a customary for polyvinyl chloride imitation leather embossing device.

The synthetic leather produced in this way and suitable for upholstery purposes shows a water vapor permeability of 200 to 300 mg per 1000 mm ² within 24 hours with respect to absolutely dry air. The air permeability is at an excess pressure of cm water column and 100 cm ² surface within ι minute between 500 and 700 ecm.

Claims (3)

Patent claims: 1. A method for producing a breathing synthetic leather from polyvinyl chloride, characterized in that that the usual polyvinyl chloride, plasticizer and pigment-containing anhydrous coatings are low Quantities, preferably 5 to 20% high molecular weight, organic substances swellable in water or organic solvents, these are swollen in a little water or solvent, incorporated and this mass in the usual way by applying heat either processed into foils or coated with woven or nonwoven webs. 2. The method according to claim 1, characterized by the additional use of hydrophilic, capillary active fillers. 3. A process according to claims 1 and 2, characterized by the additional concomitant use of _go propellants. Considered publications:
French Patent No. 909808;
U.S. Patent No. 2335702;
British Patent No. 644856. © 509704/350 4.56 (709 751/4 10.57)