CS197043B1 - Thermoplast based on polypropylene - Google Patents

Description

The invention relates to the use of polyethylene filled with finely dispersed inorganic fillers as an additive for improving the performance properties of polypropylene.

Polypropylene is known to have a relatively high softening point on the one hand, and low toughness on the other hand, especially at temperatures below 0 ° C.

It is known that the toughness of polypropylene can be improved by copolymerizing propylene with ethylene, but this process is expensive because it considerably prolongs the manufacturing process.

Therefore, the use of additives, in particular ethylene-propylene rubber, has been used in practice. However, the disadvantage of copolymerization of rubber additives is, at the same time, a deterioration in other utility properties of polypropylene, in particular a decrease in the modulus of elasticity at higher temperatures.

It is known that polypropylene cannot be modified by the addition of polyethylene, since cooling of the mixture of the two polymers leads to phase separation, i.e. both polymers form their own crystalline phases. That is why the toughness of the polypropylene cannot be increased in this way.

When studying the supramolecular structure of the finely dispersed kaolin-filled polyethylene, it was found that in the presence of the filler deep changes in the crystalline phase structure of the polyethylene occur. When the filler concentration is high, only the transcrystalline phase is practically present, the configuration of which is different from the conventional crystalline phase of unfilled polyethylene. For example, in the study of oxidative degradation in nitric acid, it has been found that the rate of degradation of the transcrystalline phase is greater than that of the crystalline phase and less than that of the amorphous phase of pure polyethylene.

It has now been found that polyethylene containing a high proportion of finely dispersed inorganic filler is readily miscible with polypropylene and that the properties of polypropylene can be modified very effectively in this way.

The use of a three-component polypropylene-polyethylene-filler mixture makes it possible, on the one hand, to achieve increased toughness even at low temperatures, on the other hand to maintain or even increase the high modulus of elasticity of polypropylene. At the same time, the filler imparts excellent processing properties to the polypropylene, which in particular include low shrinkage and easier cooling, resulting in reduced production times for injection molded, blown and extruded products.

The invention relates to a thermoplastic based on polypropylene, polyethylene and filler, characterized in that it contains 50 to 95 parts by weight of polypropylene and 5 to 50 parts by weight of polyethylene whose supermolecular structure is modified by 20 to 300% by weight of an inorganic filler such as kaolin or calcium carbonate %, based on the weight of polyethylene.

The material prepared according to the present invention has a very wide application for injection molded products (crates, machine parts), blow molded products (bottles, canisters), extruded products (profiles, tubes) and products formed from sheets and foils.

In view of its excellent mechanical properties and easy thermoplastic processing, the new material is also advantageous for the production of so-called structural foams.

The following examples illustrate the invention but do not limit or limit it.

The percentages given in the examples are by weight, with the exception of the ductility where the% is linear.

Example 1-6

The granulated polypropylene (Mosten 55 · 212 - PP I and Mosten 52.492 - PP II) was mixed with a granulate containing 50% linear polyethylene PE (liten 27 * 107, copolymer with IT flow index «0.17) and 50% modified kaolin 1 * aminopropyltriethoxysilane. The mixture of both granulates was remelted in an extruder, and the test granules of type II according to ČSN 64 0605 were made from the resulting granulate by injection molding.

From the results shown in Table I, it is evident that, while maintaining good flowability, the modulus of elasticity was increased while notch toughness was improved at 0 ° C.

Table I

Example PP% PE% Kaolin % l.T. Flexural modulus (GPa) Vrub. touževnatost Limit yield (MPa) Ductility <%) (kJ.m ² ) 23 ° C 0 ° 0 1 AND 100 ALIGN! - - 0,5 ' 1.05 21 3.5 34.5 88 2 AND 70 15 Dec 15 Dec 0.4 1.69 20 May 5.8 35.2 140 3 AND 60 20 May 20 May 0.4 1.77 17 6.2 32.9 130 4 II 100 ALIGN! - - 2.8 1.32 3.8 2,0 35.9 36 5 II 70 15 Dec 15 Dec 1.7 1.66 4.9 2.5 36.1 91 6 II 60 20 May 20 May 1.3 1.97 4.9 2.8 33.3 66

197 043

Example 7-10

Granular polypropylene (As in Examples 1-6) was mixed with a granular composite containing 50% linear polyethylene (as in Examples 1-6) and 50% micronized limestone treated with 1% stearic acid. Processing and evaluation performed as in Examples 1-6. It can be seen from Table 11 that, in this case, both the modulus of elasticity and toughness were simultaneously improved.

Table II

Example PP % PE% CaC0 ₃ % I.T. Module in bending (GPa) Notch. toughness Limit yield (MPa) Ductility % (kJ.m ^-2 ) 23 ° C Low: 14 ° C 1 AND 100 ALIGN! - - 0.5 1.05 21 3.5 34.5 88 7 AND 70 15 Dec 15 Dec 0.5 1.39 21 6.5 30.9 330 8 AND 60 20 May 20 May 0.5 1.55 28 8.3 29.7 150 4 II 100 ALIGN! - - 2.8 1.32 3.8 2,0 35.9 36 9 II 70 15 Dec 15 Dec 1.7 1.66 4.9 2.7 31.4 100 ALIGN! 10 II 60 20 May 20 May 1.45 1.71 6.0 3.6 30.0 89

Object of the invention

Claims (1)

Object of the invention Thermoplastic based on polypropylene, polyethylene and filler, characterized in that it contains 50 to 95 parts by weight of polypropylene and 5 to 50 parts by weight of polyethylene whose supermolecular structure is modified by 20 to 300% by weight of an inorganic filler such as kaolin or calcium carbonate weight of polyethylene.