CS225404B1 - Treatment of the micro-milled mica for filing of plastics - Google Patents

Description

The present invention relates to a method for treating micronized mica for the filling of plastics.

The physico-mechanical properties of polymers are improved when filling plastics with treated micronized mica. The enhancement of the physico-mechanical properties is accomplished by several known methods which modify the existing properties of the polymers. To enhance the physico-mechanical properties, the polymer matrix is reinforced by the addition of particulate and fibrous fillers of organic and inorganic origin. As fillers, for example, micronized calcium carbonate, kaolin, glass microspheres, talc, glass and carbon fibers, cellulose fibers, and micronized mica are applied.

A final increase in the physico-mechanical properties of the polymers in the mixture with fillers occurs only when perfect adhesion is achieved at the phase interface of the polymer-transition layer-filler system. The degree of adhesion is influenced, inter alia, by the content and shape of the filler particles used, its form, chemical structure, reactivity and type of finishing system. The finish of the filler is a surface treatment in which the filler becomes a chemically active component of the system by bonding it to the polymeric matrix forming the base.

Surface treatment has become quite common in the treatment of glass fibers and glass microspheres. Other fillers are prepared analogously. Calcium carbonate is treated with stearic acid or castor oil esters, calcined kaolin amines or organofunctional silanes, etc. Generally, agents containing a polymeric functional group and a mineral-functional group are applied to fillers.

It has now been found that the treatment of micronized mica for the filling of plastics, in particular polypropylene, can be advantageously carried out by the method according to the invention.

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According to the invention, the micronised mica particles are first treated with organo-functional silanes from the group of gamma-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane and vinyltris (beta-methoxyethoxy) silane or acrylic acid in an amount of 0.1 to 5 parts by weight per 100 parts by weight of mica, stabilizing, the sulfur-containing phenolic antioxidant being used in particular 2,2 * thiodiethylbis (3 (3,5-di-tert-butyl-9-hydroxyphenyl)) propionate, distearylthiodipropionate and dilaurylthiodipropionate in an amount of 0.2 to 2.0 parts by weight or its parts a mixture with an organic phosphite of the formula PO- ^R 1, ^R 2 ^{, R} 1, ^R 2 ^{, R} 2 ^{and R} 3 are alkylated phenyls having a number of carbon atoms in the alkyl radical of 9 to 18 and the ratio between phenolic antioxidant and organic phosphite in this mixture is 0.2: 1 to 20: 1, all per 100 parts by weight of mica.

The optimal concentration of antioxidants is dependent on the particle size of the filler. The following examples illustrate the method of microfining mica for polypropylene-based composites and the effect of the mica treated on the mechanical properties of the composite.

Example 1

In a Papenmeier fluidized bed mixer, micronised mica with a particle size of up to 70 µm, 1 part by weight of gamma-methylcryloxypropyltriraethoxysilane, commercial product Z-6O3O, was prepared from a 1% solution in methanol. Subsequently, 0.20 parts by weight of the antioxidant 2,2'thiodiethylbis / $ (3,5-di-tert-butyl-9-hydroxyphenyl) propionate, a commercial product of Irganox 1035, was added to stabilize the solvent. The solvent was evaporated.

The micronized mica treated in this way was used to fill polypropylene. Tested specimens were prepared from filled polypropylene and mechanical properties were determined.

Table 1 shows the effect of the addition of surface mica on the mechanical properties of the composite:

Table 1

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Mixture no. PP52492 (wt%) micronized mica? (% by weight) E-module (MPa) 1 100 ALIGN! - 1 210 2 70 30 not edit. 2 240 3 70, 30 uprav. 3 480

Example 2

In a Papenmeier fluidized bed mixer, micronised mica having a particle size of up to 70 _µm acrylic acid was _prepared in an amount of 4 parts by weight. After finishing, the mica was stabilized with a mixture of phenolic antioxidant and organic phosphite in a ratio of 1 l. The amount of phenolic antioxidant is 0.25 parts by weight. As these materials, 2,2 * thiodiethylbis [3- (3,5-di-tert-butyl-9-hydroxyphenyl) / propionate of the commercial product AO-6 was used, the exact composition of which is not mentioned, but is generally alkylphenyl phosphite. The treated micronized mica was used to fill polypropylene.

Tested specimens were prepared from filled polypropylene and mechanical properties were determined. Table 2 shows the effect of the addition of surface-treated micronised mica in comparison with untreated mica on the mechanical properties of the composite.

Claims (1)

Process for treating micronized mica for filling plastics, in particular polypropylene, characterized in that the micronised mica particles are first treated with organofunctional silanes from the group of gamma-methacryloxypropyltrimethoxysilane, vinyltriethoxy silane and vinyltris (beta-methoxyethoxy) silane or acrylic acid in an amount of 0.1 to 5% by weight parts per 100 parts by weight of mica, then the finished mica particles are stabilized using a sulfur-containing phenolic antioxidant, in particular 2,2 * thiodiethylbis / 3- (3,5-di-tert-butyl-9-hydroxylphenyl) propionate, distearyl thio dipropionate and dilauryl thiodipropionate in an amount of 0.2 to 2.0 parts by weight or a mixture thereof with an organic phosphite of the general formula Pff 1 R 2 R 6 R 6 R 6 wherein R 1, R 6 and R 6 are alkylated phenyls. with a number of carbon atoms in the alkyl radical of from 9 to 18 and a ratio between phenolic antioxidant and organic phosphite in this mixture of 0.2: 1 to 20: 1, all per 100 parts by weight of mica #