KR840000373B1 - Polypropylene composition - Google Patents

Abstract

Polypropylene compositions comprise 0.005- 8 wt.% of 1,3,2,4-di(alkylbenzylidene)sorbitol based on 100 wt.% of polypropylene. The formula of the sorbitol is indicated in the following where R is C2-4 alkyl. Obtained polypropylene compositions have much improved transparency suitable to make molded products, such as plastic vessels, packing materials, and other industrial parts.

Description

Polypropylene composition

The present invention relates to a polypropylene composition for obtaining a molded article with improved transparency and bleeding phenomenon of additives.

Since polypropylene has excellent mechanical, thermal, chemical, and electrical properties, it is used in various applications as a main raw material of the plastics industry, such as miscellaneous goods containers, packaging materials, and industrial parts. However, since polypropylene has high crystallinity, there is a strong demand for the development of polypropylene having improved transparency due to the lack of transparency of the obtained molded article.

In order to improve the transparency, various additives, such as dibenzylidene sorbitol, have been described in Japanese Laid-open Patent Publication No. 22740/76, but this method is not only insufficient in improving transparency, but also molded. There is a drawback that a bleeding phenomenon of the additive substance occurs during processing. In addition, a method of adding 1, 3, 2, 4-di (methylbenzylidene) sorbitol as reducing and reducing the bleeding phenomenon is described in Japanese Laid-Open Patent Publication No. 117,044 / 78. The problem of transparency has been solved quite a bit, but it still suffers from bleeding.

An object of the present invention is to provide a polypropylene composition useful for the production of molded articles having excellent transparency.

It is another object of the present invention to provide a polypropylene composition with little bleeding phenomenon of additives which is frequently found in conventional polypropylene compositions.

According to the present invention, the aforementioned objects of the present invention are 0.005 to 8 parts by weight, preferably 0.1 to 0.3 parts by weight of 1,3, 2,4-di (100 parts by weight of polypropylene having 2 to 18 carbon atoms per alkyl group). By adding alkylbenzylidene) sorbitol.

According to the present invention, 0.005 to 8 parts by weight of 1,3, 2,4-di (alkylbenzylidene) sorbitol represented by the following general formula is added to 100 parts by weight of polypropylene.

(Wherein R represents an alkyl group having 2 to 18 carbon atoms). When the amount of dibenzylidene sorbitol is less than 0.005% by weight, the transparency of the polypropylene is not sufficiently improved, and when the amount of dibenzylidene sorbitol is less than 8% by weight, a bleeding phenomenon occurs, so that the amount outside the above-mentioned range is not preferable.

Suitable amounts of dibenzylidene sorbitol vary slightly depending on the number of carbon atoms of the alkyl. For example, in the case of 1,3,2,4-di (alkylbenzylidene) sorbitol having an alkyl group of 2 to 8, preferably 2 to 4 carbon atoms, it is used in an amount of 0.05 to 1 parts by weight, In the case of 2,4-di (ethylbenzylidene) sorbitol, from 0.01 to 8 parts by weight, preferably from 0.05 to 1 part by weight, more preferably from 0.1 to 0.3 parts by weight, as is apparent from the examples described below. do.

The polypropylene used in the present invention includes not only isotactic polypropylene but also crystalline copolymers of propylene and ethylene or propylene and α-olefins, and mixtures thereof.

When the molded article is manufactured using the composition of the present invention, transparency equivalent to 1/2 to 1/3 of the amount of conventional additives added can be obtained. The additive used in the present invention does not cause a bleeding phenomenon even if the additive is added in the same amount as the conventional additive, and since the addition amount can be reduced as described above to obtain the required degree of practical use, substantially during molding Bleed does not happen at all. The use of known dibenzylidene sorbitol and 1,3,2,4-di (methylbenzylidene) sorbitol in the propylene homopolymer cannot improve the transparency, but the substituted dibenzylidene having the aforementioned alkyl substituents can be expected. If sorbitol is used, the transparency of the propylene homopolymer can be greatly improved, and this effect cannot be expected by the prior art.

The alkyl groups in the 1,3,2,4-di (alkylbenzylidene) sorbitol used in the present invention are all 2 to 18 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 4 carbon atoms. Examples of the preferred additive compounds having a carbon atom therein include 1, 3, 2, 4-di (ethylbenzylidene) sorbitol, 1,3,2,4-di (propylbenzylidene) sorbitol, and 1,3,2. 4-di (butylbenzylidene) sorbitol, 1,3,2,4-di (hexylbenzylidene) sorbitol and 1,3,2,4-di (octylbenzylidene) sorbitol can be enumerated. According to the position of the substituent R in the general formula, ortho, meta and para isomers exist, and all of these isomers can be used in the present invention. Although there is little difference in performance between the obtained 1,3, 2,4-di (alkylbenzylidene) sorbitol isomers, a pisomer that is practically available is preferable.

In order to improve the mechanical strength of the molded article using the composition of the present invention, it is preferable to use sorbitol and an antioxidant together.In addition to the antioxidant, hydrochloric acid inhibitors such as calcium or aluminum salts of fatty acids, ultraviolet absorbers and other stabilizers may be used. It can also be used in combination.

In preparing the composition of the present invention, sorbitol and, if necessary, antioxidants and other additives can be prepared by uniformly dispersing in polypropylene by a known means such as Henschel mixer. Particularly convenient pellets can be obtained by mixing these additives with polypropylene powder, followed by melt extruding the mixture in, for example, an extruder.

In the following, the present invention will be described in more detail by synthesizing Examples and Examples.

Synthesis Example 1

A 2-liter four-necked flask equipped with a paddle-type stirrer with a good stirring power, a temperature crab and a reflux condenser on the top, sorbitol 38.2 g (0.21 mol), p-ethylbenzaldehyde 53.7 g (0.40 mol), benzene 720 ml and p 0.38 g of toluenesulfonic acid was introduced. While stirring vigorously, heating was carried out in a hot water bath until benzene was refluxed, the reaction was continued for 8 hours, and the resulting water was collected by a liquid separator. The benzene was then distilled off, 1 L of isopropanol was added to heat the mixture until the isopropanol was refluxed, and the reaction mixture was held for 1 hour. The product was cooled, filtered and air dried, then dried in a desiccator to give 71 g of white crystals of 1,3, 2,4-di (ethylbenzylidene) sorbitol.

Elemental Analysis, C ₂₄ H ₃₀ O ₆

C (%) H (%)

Theoretic 69.54 7.29

Found 69.63 7.24

Synthesis Example 2

In Synthesis Example 1, 64.1 g (0.40 mol) of n-butylbenzaldehyde instead of p-ethylbenzaldehyde and 720 ml of toluene instead of benzene were used to carry out the same reaction as in Synthesis Example 1, and then toluene was distilled off, methanol and water And a mixture (1: 1) were added to disperse the solid. The product was filtered, air dried and dried in a desiccator to obtain 50 g of a pale yellow solid, which was 1,3,2,4-di (propylbenzylidene) sorbitol.

Elemental Analysis, C ₂₄ H ₃₄ O ₆

C (%) H (%)

Theoretical 70.56 7.74

Found 71.3 7.81

Synthesis Example 3

In Synthesis Example 1, 64.1 g (0.40 mol) of n-butylbenzaldehyde instead of p-ethylbenzaldehyde and 720 ml of toluene instead of benzene were used to carry out the same reaction as in Synthesis Example 1. Next, toluene was distilled off, and a mixture of methanol and water (1: 1) was added to disperse the solid. The product was filtered, air dried and dried in a desiccator to obtain 63 g of a white solid that was 1,3, 2,4-di (butylbenzylidene) sorbitol.

Elemental Analysis, C ₂₈ H ₃₈ O ₆

C (%) H (%)

Theoretical 71.46 8.14

Found 72.1 8.22

Example 1

100 parts by weight of propylene homopolymer having an intrinsic viscosity of 1.62 and tetrakis [methylene-3 ', 5'-tert-butyl-4'-hydroxyphenyl) propionate] methane at 135 ° C Part and 0.1 to 0.3 part of each of the sorbitol derivatives obtained in Synthesis Examples 1 to 3 were blended in a Henschel mixer, and then pelletized through an extruder maintained at a maximum temperature of 200 ° C. Next, a sheet having a thickness of 2 mm was formed by an injection molding machine holding the pellet at a maximum temperature of 210 ° C., and the haze meter was measured by a haze meter (TC-H2 type, manufactured by Tokyo Color Co., Ltd.). And bleeding to the mold surface during injection molding were observed.

The results are shown in the first table.

From the results of Table 1, the composition containing the above-described sorbitol derivatives of the present invention is, of course, not mixed with dibenzylidene sorbitol and 1,3,2,4-di (meth-methylbenzylidene) sorbitol of Comparative Example. Transparency was remarkably superior to the same amount, respectively, and the bleeding phenomenon was not observed.

TABLE 1

( ^* ) The bleed shape was determined as follows.

0: no bleed phenomenon

1: slightly bleed

2: bleeding phenomenon

3: fairly bleeding phenomenon

Example 2

The procedure of Example 1 was followed except that ethylene-propylene random copolymer having an ethylene content of 3.3% by weight and an intrinsic viscosity of 1.62 measured in tetralin at 135 ° C. was used instead of the propylene homopolymer. It was repeated. The results of the channel measurement and the observation results of the bleed are listed in Table 2 below.

From the results of the following Table 2, the composition containing the aforementioned sorbitol derivatives of the present invention was, of course, unmixed, and of course, dibenzylidene sorbitol and 1,3, 2,4-di (meth-methylbenzylidene) sorbitol and The transparency was remarkably superior to that in which the same amount was respectively added, and the bleeding phenomenon was not observed.

TABLE 2

( ^* ) The same meaning as in the first table.

Claims (1)

1,3,2,4-di (alkylbenzylidene sorbitol, represented by the following general formula and wherein R represents an alkyl group having 2 to 4 carbon atoms, is added in an amount of 0.005 to 8 parts by weight based on 100 parts by weight of polypropylene: Polypropylene composition, characterized in that.