KR20000055011A - Polypropylene resin composition with good processibility and transparency - Google Patents

Abstract

The present invention comprises 0.01 to 0.04 parts by weight of peroxide and 0.1 to 0.3 parts by weight of sorbitol-based nucleating agent based on 100 parts by weight of propylene-ethylene random copolymer resin having an ethylene content of 2 to 5 mol%. It is related with the polypropylene resin composition which improves workability as a melt index becomes high, and also improves transparency, and also has more excellent transparency using a sorbitol-type nucleating agent.

Description

Polypropylene resin composition excellent in processability and transparency {POLYPROPYLENE RESIN COMPOSITION WITH GOOD PROCESSIBILITY AND TRANSPARENCY}

The present invention relates to a polypropylene resin composition having excellent processability and transparency, and more particularly, to a polypropylene resin, which includes a propylene-ethylene random copolymer resin, a peroxide and a sorbitol-based nucleating agent, and has excellent processability and improved transparency. It relates to a polypropylene resin composition having.

Among polyolefin resins, polypropylene is generally used as a transparent injection product because polypropylene has excellent rigidity, rigidity, tensile strength, and heat resistance. Of these, polypropylene polymerized solely with propylene has a limitation in improving transparency because it is basically high in isotacticity. In order to increase the low transparency, a propylene-ethylene random copolymer has been developed in which a certain amount of ethylene is added and copolymerized when the propylene is polymerized. The propylene-ethylene random copolymer is synthesized into a powder having a suitable melt index having good processability in a resin production reactor, and a kneaded benzylidene sorbitol-based nucleating agent, calcium stearate, and an oxidation stabilizer are added and kneaded to prepare a resin composition. A related domestic patent is 87-009914.

However, the conventional transparent injection-molding resin composition prepared as described above increases the amount of nucleating agent added for improving transparency, and the transparency improving ability of the nucleating agent also reaches its limit. In addition, since the resin synthesized in the production process is generally high in molecular weight, it is difficult to produce a resin with a high melt index to improve processability.

It is an object of the present invention to improve the above problems and to provide a polypropylene resin composition having excellent processability and particularly excellent transparency by adding a peroxide and a sorbitol-based nucleating agent to a propylene-ethylene random copolymer resin.

The polypropylene resin composition of the present invention contains 0.01 to 0.04 parts by weight of peroxide and 0.1 to 0.3 parts by weight of sorbitol-based nucleating agent based on 100 parts by weight of propylene-ethylene random copolymer resin having an ethylene content of 2 to 5 mol%.

In the present invention, as the propylene-ethylene random copolymer resin, propylene-ethylene random copolymer resin containing 2 to 5 mol% of ethylene which is a copolymerization monomer and having a melt index of 4 to 10 g / min is used.

As the peroxide used in the present invention, for example, bis (tert-butylperoxyiso-propyl) benzene (bis) or dicumyl peroxide is used, and propylene-ethylene random It is preferable to add 0.01-0.04 weight part with respect to 100 weight part of copolymer resins. If it is less than 0.01 part by weight or more than 0.04 part by weight, workability is inferior.

The reason for adding the peroxide in the present invention is to compensate for the disadvantage of poor processability of propylene-ethylene random copolymer having a large ethylene content of 2 to 5 mol% and to improve transparency. In other words, by using a peroxide, controlled chain scission is performed to decompose long chains of high molecular weight, thereby improving flowability, thereby improving processability. As a result, the crystallization rate is reduced, thereby improving transparency.

Compared to polypropylene polymerized only with propylene, propylene-ethylene copolymers require the addition of higher amounts of peroxide to obtain the desired melt index. This is because when the propylene alone, the peroxide only undergoes a chain decomposition reaction, but when ethylene is copolymerized, branching and crosslinking are caused to decrease the increase of the melt index.

The nucleating agent used in the present invention may be a benzylidene sorbitol-based nucleating agent (DBS) that has been conventionally used for improving transparency, but 3,4-dimethylbenzylidene sorbitol-based nucleating agent (DMDBS), which is known to be excellent in transparency and stability, may be used. It is preferable to use, and it is preferable to add 0.1-0.3 weight part with respect to 100 weight part of propylene ethylene random copolymer resins. When the content of the added nucleating agent is less than 0.1 parts by weight, the transparency is inferior, and when the content of the nucleating agent is more than 0.3 parts by weight, the effect of improving transparency due to the increase of the nucleating agent content is insufficient.

The present invention can be understood in more detail by the following examples and comparative examples, the following examples are only for illustrating the present invention and are not intended to limit the protection scope of the present invention.

How to measure

Melt Index: ASTM D1238, 230 ℃, 2.16kg

Haze: ASTM D1003A

Example 1

0.01 parts by weight of peroxide, 0.2 parts by weight of nucleating agent, 0.2 parts by weight of other additives (0.1 parts by weight of neutralizing agent, 0.05 parts by weight of antioxidant, 0.05 parts by weight of antioxidant, 0.05 parts by weight based on the composition shown in Table 1 below). B) was added and kneaded and extruded at 210 ° C. using a twin screw extruder to prepare pellets having a diameter of about 2 mm. Melt index was measured to measure the workability of the prepared pellets, and 2 mm sheet specimens were made by using an injection machine to measure transparency. The injection machine used was Samsung Klimkner FM140TON, the injection conditions were nozzle temperature 200 ℃, mold temperature 60 ℃ was fixed and the injection pressure was carried out in the range of 50 ~ 120 bar. Table 2 shows the melt index (processability) and the haze value (transparency).

Examples 2-4

The same resin as in Example 1 was used, and the peroxide content was changed as shown in Table 1 to evaluate workability and transparency after fabrication of the specimen in the same manner as in Example 1. The results are shown in Table 2.

Examples 5-6

Using the same resin as in Example 1, experiments were carried out by changing the peroxide and nucleating agent type as shown in Table 1, and evaluated the workability and transparency after fabrication of the specimen in the same manner as in Example 1. The results are shown in Table 2.

Examples 7-8

The random copolymer resin having a different ethylene content from Example 1 was experimented with the same amount as in Example 1 to evaluate the processability and transparency after fabrication of the specimen in the same manner as in Example 1. The results are shown in Table 2.

Comparative Examples 1 to 4

The resin, nucleating agent, and peroxide composition were changed as shown in Table 1, and the processability and transparency were evaluated after fabrication of the specimen in the same manner as in Example 1. The results are shown in Table 2.

(Unit: parts by weight based on 100 parts by weight of resin) Suzy Peroxide Nuclear agent Other additives Kinds Kinds amount Kinds amount amount Example 1 Resin 4 P 1 0.01 Nucleus 1 0.2 0.2 Example 2 Resin 4 P 1 0.02 Nucleus 1 0.2 0.2 Example 3 Resin 4 P 1 0.03 Nucleus 1 0.2 0.2 Example 4 Resin 4 P 1 0.04 Nucleus 1 0.2 0.2 Example 5 Resin 4 P 1 0.02 Nucleus 2 0.2 0.2 Example 6 Resin 4 P 2 0.02 Nucleus 1 0.2 0.2 Example 7 Resin 2 P 1 0.02 Nucleus 1 0.2 0.2 Example 8 Resin 3 P 1 0.02 Nucleus 1 0.2 0.2 Comparative Example 1 Resin 1 P 1 0.02 Nucleus 1 0.2 0.2 Comparative Example 2 Resin 4 - - Nucleus 1 0.2 0.2 Comparative Example 3 Resin 4 - - - - 0.2 Comparative Example 4 Resin 4 - - Nucleus 1 0.3 0.2

※ In Table 1,

(1) resin

Resin 1: Homopolypropylene, melt index 7-9 g / min

Resin 2: Propylene-ethylene random copolymer, melt index 7-9 g / min,

Ethylene Content 2.6 mol%

Resin 3: propylene-ethylene random copolymer, melt index 7-9g / min,

4 mol% of ethylene content

Resin 4: propylene-ethylene random copolymer, melt index 7-9g / min,

Ethylene Content 4.5 mol%

(2) peroxide

P 1: bis (tertiary-butylperoxyiso-propyl) benzene

P 2: Daikyu Mill Peroxide

(3) nuclear agent

Nucleating agent 1: 3,4-dimethylbenzylidene sorbitol (DMDBS)

Nucleating agent 2: benzylidene sorbitol (DBS)

(4) other additives

Antioxidant 1: Iganox-1010

Antioxidant 2: Igafos-168

Neutralizer: Calcium Stearate

division Haze (%) Melt Index (g / min) Example 1 35 16 Example 2 31 22 Example 3 28 34 Example 4 28 40 Example 5 32 24 Example 6 31 23 Example 7 36 26 Example 8 35 23 Comparative Example 1 48 31 Comparative Example 2 40 8 Comparative Example 3 69 8 Comparative Example 4 36 8

* Haze indicates that the lower the value, the better the transparency.

As shown in Table 2, in Examples 1 to 4, the nucleation was fixed at 0.2 parts by weight, and the peroxide content was changed from 0.01 to 0.04 parts by weight, while the transparency and the comparison with the comparative example 4 without the peroxide added. It can be seen that the processability is improved. In particular, it can be seen that the melt index can be adjusted to a desired range from 10 to 40.

As in the case of Examples 5 to 6 and Comparative Example 1, when the peroxide content was the same and the propylene-ethylene random copolymer resin and the homopolypropylene resin were used, the propylene-ethylene random copolymer resin was added. In this case, it can be seen that transparency is better.

As shown in Comparative Examples 2 to 4, when the nucleation was changed from 0 to 0.3 parts by weight without adding peroxide, the workability was decreased, and when 0.3 parts by weight, the degree of transparency improvement was very small.

As can be seen from the above, the polypropylene resin composition prepared by the present invention has excellent transparency and processability, which is superior in transparency to conventional polypropylene resin compositions, and can be easily adjusted to suit various users. Can be applied.

Claims (4)

A polypropylene resin composition comprising 0.01 to 0.04 parts by weight of peroxide and 0.1 to 0.3 parts by weight of sorbitol-based nucleating agent, based on 100 parts by weight of propylene-ethylene random copolymer. The polypropylene resin composition according to claim 1, wherein the propylene-ethylene random copolymer has an ethylene content of 2 to 5 mol% and a melt index of 4 to 10 g / min. The polypropylene resin composition according to claim 1, wherein the peroxide is bis (tertiary-butylperoxyiso-propyl) benzene. The polypropylene resin composition according to claim 1, wherein the sorbitol-based nucleating agent is 3,4-dimethylbenzylidene sorbitol.