CS265102B1 - A composition based on aliphatic polyesterurethanes for forming a cover layer for plastic materials - Google Patents

Abstract

The solution concerns the improvement and expansion of the application possibilities of mixtures based on aliphatic polyesterurethanes, intended for the covering layers of materials based on plasticized PVC. The purpose of the invention is to expand the application possibilities of aliphatic polyesterurethanes as covering layers of PVC materials, created by indirect application, to areas of medium-deep sharply drawn patterns, to further expand the range of release papers usable for the given purpose also from the point of view of the so-called "release" and to prevent the formation of defects in the covering layer. The above is achieved by using, instead of the usual solutions of aliphatic polyesterurethanes, a mixture whose dry matter contains 30 to 90 weight percent of aliphatic polyesterurethanes and 10 to 70 weight percent, preferably 50 weight percent, of a PVC plasticizer, preferably di-2-ethylhexyl phthalate, which during gelation passes from the PUR layer to the PVC layer as a result of the establishment of an equilibrium between the two polymer phases.

Description

The invention relates to solutions of polyurethanes, in particular aliphatic polyester urethanes and aliphatic polyester urethane, used to form a cover layer for plastics materials whose top layer is formed by a deposit of polymers or copolymers of vinyl chloride.

In the production of these materials, the so-called indirect application technology prevails, which enables the production of materials of the required mechanical properties, coloring, tread, matt or glossy surface on a single production equipment in one working cycle. The polyurethane coating provides excellent abrasion and repeated bending resistance. At the same time, it gives the materials a dry, leathery feel and prevents the migration of plasticizers from the softened layers of vinyl chloride polymers. Their resistance to light is also significant.

The polyurethane layer is applied first to the release paper, usually in the form of a solution in organic volatile solvents. A mixture of isopropyl alcohol and toluene is used. A relatively low temperature and a short period of time is sufficient for their evaporation. However, the volatility of solvents is disadvantageous when forming a higher layer of deposition of said solutions. The solvent is closed under the dried top layer, which then causes bubbles in the coating or separates the film from the release paper. These defects occur even at relatively low build-up if the design of the release paper is not completely shallow. These drawbacks considerably limit the choice of release papers and hence the aesthetic value of the materials produced. To overcome these drawbacks, a greater amount of higher boiling solvents, such as glycol ethers or dimethylformamide, is usually added to the polyurethane solutions. The disadvantage, however, is the high toxicity of said substances and only a partial improvement in the quality of the deposited coating. Defects arise easily when handling PUR-coated release paper. Due to the high rigidity of the dried PUR film itself, the tension between the paper and the PUR film is handled resulting in a local tear of the film from the paper. This leads to a further reduction in the choice of release papers, in terms of the so-called release, which is a measure of the adhesion of the PUR film to the surface of the design paper. However, this relationship varies during production due to the diffusion of a portion of the plasticizers from the subsequently applied paste layer of polymers or copolymers of vinyl chloride as a result of establishing a thermodynamic equilibrium between the two polymer phases.

These drawbacks are eliminated according to the invention by reversing the direction of diffusion, i.e. by adding an amount of a suitable PVC plasticizer to the PUR solution. This in the drying phase facilitates solvent flow and later positively counteracts the tearing off of the PUR film from the release paper due to its softening. After application of the PVC layer and subsequent gelation, it then diffuses into the PVC layer. Due to the high ratio of PVC layer to PUR layer and the very small thickness of the PUR coating layer (10 to 30 pm), which allows a considerable extent of the diffusion process and thus a significant approximation to the equilibrium state of the resulting material, changes only slightly. Another advantage is the saving of part of the solvents.

Thus, the proposed process does not require the use of toxic glycol ethers or dimethylformamide for PUR base solutions used as coatings for PVC coatings. Also, when diluting them before application to the embossing paper, the need for the use of toluene, which can be replaced by a PVC plasticizer, can be eliminated or eliminated. Di-2-ethylhexyl phthalate, butylbenzyl phthalate, dioctyladipate and the like may be used in an amount of from 10 to 200% plasticizer per PUR solids, most preferably di-2-ethylhexyl phthalate in an amount of about 100% per PUR solid. The most advantageous type and amount of plasticizer used depends to some extent on the type of the embossing paper, the type of PUR and the nature of the PVC coating.

Example 1

To 100 g of a 25% aliph. polyesterurethanes in toluene isopropyl alcohol: 2-methoxypropanol 50: 45: 5 (supplied by the manufacturer) is added:

g of di-2-ethylhexyl phthalate g of isopropyl alcohol

After thorough mixing and venting, apply to Chevreau TK V.N.S.

(by Warren) using a roller against a roller in a wet coating thickness of 80 g / m ² .

The coating is dried at 60 to 120 ° C for 2 min. The PUR coating is overcoated with two coatings of PVC paste consisting of 100 parts PVC and 65 parts di-2-ethylhexyl phthalate. The cotton fabric is laminated to the last PVC layer after pre-gelatinizing the first PVC layer for 1 min at 120 ° C and gelling for 3 minutes at 180 ° C. After cooling, the material is separated from the release paper. The obtained material is defect-free, has a dry and wet abrasion resistance higher than 100 kc, and a repeated bending resistance higher than 150 kc.

Example 2

A PUR solution according to Example 1) was prepared and the material was prepared as described above using Delta TK IR (Warren) release paper.

Example 3

A PUR solution according to Example 1) was prepared with an increased amount of 30 g of di-2-ethylhexyl phthalate and the material produced using the Ultracast II release paper as described above. Aries (medium deep tread).

He attaches

It shall apply:

100 g of 25% aliph. g of toluene g of isopropanol g of di-2-ethylhexyl phthalate are added as in example 1.

Example5

It shall apply:

100 g of 25% aliph. polyesterurethane (as in Example 1) g toluene g isopropyl alcohol g butylbenzyl phthalate is added as in Example 1).

In all of the above examples of material manufacture, the resulting product is free from defects, otherwise it does not differ in appearance, feel and mechanical testing from the material produced in the original softener-free process, differing only in appearance defects represented by non-tinted glossy areas caused by premature separation of PUR. paper or bubbles enclosed in the PUR layer.

Claims (1)

Mixture based on aliphatic polyesterurethanes for the formation of a coating for plastic materials based on polymers or copolymers of vinyl chloride, characterized in that it consists of a solution in a mixture of alcohols and aromatic hydrocarbons, containing from 30 to 90% by weight of aliphatic polyurethane and 10 to 70 weight percent of a plasticizer of polyvinyl chloride, preferably di-2-ethylhexyl phthalate.