CS239984B1 - Mixture with improved adhesion on polyvinylchloride base - Google Patents

Abstract

The present invention relates to polymer blends based on polyvinyl chloride plastisols. The compositions contain at least two Different types of PVC, one of which is increased the ability of the plasticizer to be absorbed characterized by the time of absorption of the plasticizer standard conditions within 4-14 minutes in this case the ratio of the amount of PVC to said absorption capacity to other polymers is 0.2: 1 to 4: 1. PVC with increased absorption capacity reduces the amount of free plasticizer in the mixture, thereby increasing adhesion to different substrates while maintaining rheological properties in particular the viscosity required from the technological reasons. Other blend advantages according to the invention there are also shorter times a lower gelation temperatures.

Description

The invention relates to polyvinyl chloride-based polymer compositions with improved adhesive properties. Properties · Mixtures are intended for protective coatings of steel sheets, fittings, profiles and their joints after heat treatment.

It is known that the adhesion of gelled mixtures of vinyl polymers to various surfaces depends on n _and the concentration of unbound plasticizer in the mixture when the adhesion creates · Irrespective of the type of plasticizer or substrate adhesion increases with increasing concentration up to a certain maximum. As the plasticizer content increases further, the adhesion decreases due to a decrease in the cohesive strength of the coating and a reduction in the contact area of the polymer with the substrate.

However, when selecting the composition of the compositions, in particular the emollient content, it is not possible to follow only the described relationships with regard to the adhesion of the coating. The compositions are most often applied by spraying or spraying. The condition of satisfactory operation of these technological operations is certain values of theological properties, especially viscosity. Practically lowering the viscosity to the required value generally assumes the use of such a high amount of plasticizer in the composition that is already beyond the maximum dependence of adhesive strength on the plasticizer concentration. This deficiency can only be partially eliminated by gelatinisation with a high content of plasticizers at higher temperatures and for extended periods of time, which, however, entails prolonging the entire process and increasing energy costs.

It is therefore an object of the present invention to find plastisol coating compositions which suitably satisfy both the process requirements and the quality requirements of the gelatinous coating itself, in particular its sufficient adhesion.

It has now been found that compositions of this invention essentially meet 10-50% by weight of at least two types of polyvinyl chloride, at least one of which has a plasticizer absorption time under standard conditions of from 4 to 14 minutes with a polyvinyl chloride ratio of with said absorbency to polyvinyl chloride having a different absorbency is 0.2: 1 to 4: 1/3, preferably 0.4: 1 to 2: 1 and 20-70% by weight of an plasticizer or an ester-type plasticizer mixture; 70% by weight filler, 0.1-6% by weight adhesive and 0.1-10% by weight other conventional additives such as pigments, stabilizers or blowing agents ·

The absorption time of the plasticizer under standard conditions is defined herein. The time determined by the method according to ASTM D 2396-69. The vinyl polymer powder is mixed in a Brabender plastigraph kneader and after preheating at 93 ° C dioctyl phthalate is added. free-flowing powder · The transition from a wet lump to a dry powder is accompanied by a rather significant change in torsional moment. The dry powder formation time, i.e. the time from the addition of the dioctyl phthalate to the point where the mixture becomes dry, characterizes the absorption rate of the vinyl polymers. Typical absorption times for vinyl polymers having a high plasticizer-binding capacity are in the range of from 4 to 14 minutes, in particular from 4 minutes to 10 minutes. Vinyl polymers that do not have an increased plasticizer absorption capability do not exhibit the described torsional moment change.

Polymers with enhanced plasticizer absorption capacity are used to prepare plasticized dry extruded compositions.

When used in gelling compositions, said type of polymer is exerted by its plasticizer binding ability such that:

239 984 at the beginning of the gelatinization process there is a rapid absorption and a reduction of the free plasticizer content in the mixture. Since the adhesive properties of the composition are related specifically to the free plasticizer content, the adhesion value will approach the maximum values of _t , even at a higher total plasticizer content in the composition. At the same time, the conditions of adhesive bond formation have a favorable effect on lower temperatures and shorter gelation times.

The preferred weight ratio of the different vinyl polymers to each other is given by the ratio of the weight of the polymers with increased absorbency to the weight of the other polymers and is in the range of from 0.2: 1 to 4: 1, preferably 0.4: 1 to 2: 1.

In order to further elucidate the invention, the following examples are provided:

Example 1

Mixture

A B

Polyvinyl chloride pasty form 18.00 10.00 Polyvinyl chloride with increased absorption (absorption rate 8.5 minutes according to ASTM D 2396-69) 0 8.00 Dioctyl phthalate 25.85 25.85 2,2,4-trimethyl-1,3-pentanediol diisobutyrate 4.00 4.00 tribasic lead sulphate 0.35 0.35 resorcin 0.35 0.35 hexamethylenetetramine 0.15 0.15 silicon dioxide 0.75 0.75 calcium carbonate 48.55 48.55 calcium oxide 2.00 2.00

239 984

The adhesion of the polyvinyl chloride mixtures A and B to the raw, non-degreased steel sheet was evaluated by a peel test on a 10 mm wide strip after gelation:

(a) at 140, 150 and 160 ° C and a gelling time of 15 minutes

140 ° C 150 ° C 160 ° C

b) at temperature easy peel easy peel can not peel can not peel can not peel can not peel

120, 130 and 140 ° C and a gel time of 30 minutes

120 ° C 130 ° C 140 ° C

And easy peel easy peel cannot be peeled off

B Cannot Peel Cannot Peel Cannot Peel

For mixture A without a polyvinyl chloride combination, adhesion to the substrate was achieved at a gelatinization temperature of 160 ° C in 15 minutes and at a gelatinization temperature of 140 ° C in 30 minutes, whereas for the same comparative mixture B with the combination according to the invention at 20 ° C lower, i.e. 15 minutes at a gelatinization temperature of 140 ° C in 30 minutes at a gelatinization temperature of 120 ° C. At the same gelation temperature / e.g. 140 ° C adhesion to the substrate was achieved for mixture A in 30 minutes and for mixture B in 15 minutes.

Example 2

Mixture

C D Polyvinyl chloride pasty form 18.00 10.00 Polyvinyl chloride with increased absorption. (absorption rate 8.5 minutes according to ASTM D 2396-69) 0 8.00 Dioctyl phthalate 26,00 26,00 2,2,4-trimethyl-1,3-pentanediol sobutyrate 4.00 4.00 silicon dioxide 0.50 0.50 amineamide resin 1.00 1.00 calcium oxide 1.00 1.00 calcium carbonate 49.50 49.50

239 984

The adhesion of the mixtures C and D to the electrophoretic priming varnish was evaluated by a peel test on a 10 mm wide strip after gelation:

(a) at temperature

140 ° C 150 ° C 160 ° C

(b) at temperature

120 ° C 130 ° C 140 ° C

140, 150 and 160 ° C and a gelling time of 15 minutes C D

120, easy peel can not easy peel can not peel very difficult can not

130 and 140 ° C and the gelation time 30

C D Peel Peel Peel Minutes Easy Peel Easy Peel Can't Peel Can't Peel Can't Peel Can't Peel

For mixture C without a polyvinyl chloride combination, adhesion to the substrate was achieved at a gelatinization temperature of 160 ° C in 15 minutes and at a gelatinization temperature of 140 ° C in 30 minutes, whereas for the same comparative mixture D with the combination according to the invention at 20 ° C lower, i.e. 15 minutes at a gelatinization temperature of 140 ° C and 30 minutes at a gelatinization temperature of 120 ° C. At the same gelatinization temperature of e.g.

Example 3

Mixture

E F

Polyvinyl chloride paste - forming 22,00 14.00 Polyvinyl chloride with increased absorption (absorption rate 4.5 minutes according to ASTM D 2396-69) 0 8.00 Dioctyl phthalate 35,00 35,00 Calcium carbonate 40.00 40.00 Stabilizer Ca / Zn 0.65 0.65 Resorcin 0.50 0.50 Hexamethylenetetramine 0.35 0.35 Calcium oxide 1.50 1.50

239 984

The adhesion of the mixtures E and F to the raw, non-degreased steel sheet was evaluated by a peel test on a 10 mm wide strip after gelation at 140, 150, 160 and 170 ° C and a gelation time of 20 minutes:

E F 140 [deg.] C easy peeling peeling very difficult 150 [deg.] C easy peeling cannot peel off 160 ° C odlup difficult cannot peel off 170 [deg.] C cannot peel off cannot peel off

For the mixture without the polyvinyl chloride combination, adhesion was achieved at a gelatinization temperature of 170 ° C in 20 minutes, while for the same comparative mixture F e by the combination according to the invention at a temperature of 20 to 30 ° C lower.

Claims (1)

Mixtures with increased adhesion to polyvinyl chloride-based substrates, characterized in that they contain 10-50% by weight of at least two types of polyvinyl chloride, at least one of which has a plasticizer absorption time under standard conditions of from 4 to 14 minutes, the absorbency to polyvinyl chloride having a different absorbency is 0.2: 1 to 4: 1, preferably 0.4: 4 to 2: 1, and 20-70% by weight of an emollient or ester-type plasticizer mixture, 0.1-70% by weight % filler, 0.1-6% by weight adhesive and 0.1-10% by weight other conventional additives such as pigments, stabilizers or blowing agents *