JPS6081206A - Modified polypropylene - Google Patents

Abstract

PURPOSE:To obtain a modified polypropylene of improved moldability and impact resistance, by incorporating organic peroxide in a crystalline ethylene-propylene block copolymer of high melt flow rate (MFR) fallowed by heat treatment in a specific condition. CONSTITUTION:(A) 100pts.wt. of a crystalline ethylene-propylene block copolymer with a MFR 3-15g/10min is admixed with (B) pref. 0.01-0.2pt.wt. of an organic peroxide (e.g., t-butyl peroxyacetate), followed by heat treatment at 180-300 deg.C so that the MFR of said copolymer (MFRA) and that of the final modified polypropylene (MFRB) satisfy the equation: logMFRB/logMFRA=1.25- 5.0, thus obtaining the objective polypropylene. EFFECT:Capable of obtaining high-MFR polypropylene using conventional equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to modified overmodified propylene with improved moldability and impact resistance.

Conventionally, polypropylene with excellent impact resistance has been typified by crystalline ethylene-propylene Bronok copolymer, which is a copolymerization of ethylene and propylene. (increasing the rate), the impact resistance tends to decrease.

For this reason, even a crystalline ethylene-propylene Bronoch copolymer with a high melt flow rate has a nord flow rate of about 9 to 15y/1o at most, and in recent years, there has been an emphasis on cost saving and energy saving.

There is a demand for higher flow materials and thinner products.
Furthermore, polypropylene with high melt flow rate and excellent impact resistance is expected to be produced.

As a method for improving impact resistance, the ethylene concentration in the polypropylene resin can be increased, or the ethylene concentration in the polypropylene resin can be improved.
Polymer alloys and the like are common.

However, even if this method is applied to produce polypropylene with a high melt flow rate and excellent impact resistance, it is not practical due to the following drawbacks. In other words, if you want to increase the ethylene concentration in polypropylene resin, you can't do it with the current manufacturing equipment.

There is a limit to the copolymerization of ethylene and propylene, and as the ethylene concentration increases, more atactic polypropylene components are removed in the deashing step, which lowers productivity and increases costs. On the other hand, in the case of polymer alloys whose impact resistance is improved by adding commercially available ethylene-propylene rubber, etc., ethylene-propylene rubber is more expensive than polypropylene resin, and an extruder with good kneading effect is used. If the temperature is too high, the effect will not be fully demonstrated, resulting in a considerable increase in cost.

The inventors conducted extensive research with the aim of producing polypropylene with a high melt flow rate and excellent impact resistance using conventional polypropylene production equipment. One of the major characteristics of this polymer is that it exhibits a unique behavior in that it retains some of the performance of the starting material polypropylene before decomposition, even after decomposition. They discovered that by reducing the molecular weight with peroxide, a modified polypropylene with a high melt flow rate and excellent impact resistance could be obtained, and the present invention was completed.

That is, in this invention, the melt flow rate is 3 to 15.
L? When the crystalline ethylene-propylene block copolymer and organic peroxide are mixed and heat-treated for 710 minutes, the Nordfluororate of the crystalline ethylene-propylene block copolymer before heat treatment is MFRA g/10. If the nord fluororate of modified polypropylene obtained by heat treatment is M F RBy/1o min, then 10 g M F
The present invention relates to a modified polypropylene with improved moldability and impact resistance, which is obtained by heat treatment at 180 to 000C so that RB/10gMFRA is 1.25-5.0.

The crystalline ethylene-propylene block copolymer used in this invention has a melt flow rate of 5.
~152/10 minutes are used, and known antioxidants, ultraviolet absorbers, organic carbo/acid metal salts such as aluminum salts and sodium salts of benzoic acid, inorganic substances such as talc, pigments and antistatic agents, Glycolic acid, carbon number 10-2
A slip agent such as fatty acid No. 2 may be appropriately blended. If the melt flow rate of the crystalline ethylene-propylene block copolymer used is outside the above range, the melt flow rate will be large and the moldability will be improved, and it is possible to obtain a modified polypropylene with excellent impact resistance. I can't.

1ri as the organic peroxide used in this invention.
, an organic peroxide having a one-minute half-life temperature near the melting temperature of the crystalline ethylene-prohymbronochloride copolymer, and the like.

For example, t-butyl peroxide acetate, t-butyl peroxide/PETZ, dicumyl peroxide 1
t-butyl peroxyinbropyl carbonate, di-t
-butylshiba-oxy7phthalate 1,2.5-dimethyl-2,5-di(penzoylbaroxy)hexene-3,
Examples include t-butyl peroxylaure i-, t-butyl peroxide/maleic acid, methyl ethyl ketone peroxide, and 1-butyl cumyl peroxide. In particular, as the organic peroxide, a powdered peroxide made from a mixture of the above-mentioned organic peroxide and highly dispersed silicic acid anhydride can be suitably used. The organic peroxide is preferably blended in an amount of 0.01 to 0.2 parts by weight per 100 parts by weight of the crystalline 1-niethylene-70-pyreno block copolymer.

The modified polypropylene of the present invention is prepared by mixing the crystalline ethylene-propylene/block copolymer and an organic peroxide at 180 to 500°C, preferably at 19°C using a mixer such as an extruder.
The melt flow rate of the crystalline ethylene-propylene block copolymer before the heat treatment and the melt flow rate of the modified polypropylene obtained by the heat treatment are calculated as MFRAf/10 min and MFRB7, respectively. /10 minutes = 10g MF RB
/1 og M FRA can be obtained by heat treatment so that RA is 1.25 to 5.0. In this invention, it is necessary that the melt flow rate of the crystalline ethylene-propylene block copolymer before heat treatment and the melt flow rate of the modified polypropylene obtained by heat treatment are within the above-mentioned limited ranges. Nord flow rate is 2o7/1o or more, especially 3
0f710 minutes or more, and the fracture energy (-1o℃) showing impact resistance according to the measurement method described below is 300Kg.
-6 m or more, it is possible to obtain modified polypropylene with excellent moldability and impact resistance.

According to this invention, there is no need to increase the ethylene concentration in the crystalline ethylene-propylene block copolymer, and there is no need to add a dynamometer impact modifier or the like like in ethylene-propylene rubber.

Modified polypropylene with a high melt flow rate and excellent impact resistance can be obtained, but if necessary, it is necessary to increase the ethylene concentration in the crystalline ethylene-propylene block copolymer and add ethylene-propylene rubber, etc. If appropriate, the impact resistance can be further improved without the effect being significantly affected by peroxide decomposition.

Examples and comparative examples are shown below.

The impact resistance of modified polypropylene was evaluated on each side by dropping a steel missile at high speed onto a sample (disk molded using an injection molding machine) fixed to a frame using a high-speed impact tester. The stress at the time of destruction is measured using a load cell.The falling speed of the missile is determined by measuring the speed just before it hits the sample using a phototube.The stress-strain curve at the time of destruction is created by creating a stress-strain curve 'i= This was done by calculating the area of the quadrupled portion and calculating the fracture energy (K9 cm).

The melt flow rate of polypropylene was measured on each side below.

Examples 1 to '5 Ethylene content 5.5% by weight, melt flow rate filter,
BHTO to 100 parts by weight of powder of crystalline ethylene-propylene bronok copolymer of 9 and 15S'710 min.
, 1 part by weight, Irganox 1 0 1 00, 1
Parts by weight, 0.1 parts by weight of stearic acid/calcium acid, and 2,5 13-40 parts by weight of Bar Hekiza were mixed in the proportions shown in Table 1, premixed in a Henschel mixer, and then this mixture was set at 190 to 250°C. A pellet of modified polypropylene was obtained by melt-kneading using an extruder. Using this modified polypropylene pellet, a disk with a diameter of 100 m and a thickness of 1.6 pieces was molded using an injection molding machine. Using this disc, a high speed impact tester (High Speed Impact Tester) was used.
Impact Tesjer), the fracture energy at -10°C.

The impact resistance was evaluated. The results are shown in Table 1.

Example 4 Ethylene content 5.5% by weight, Melt Flow Ray 1-9
1'710 minutes of crystalline ethylene-propylene alcohol//
95 parts by weight of copolymer powder, ethylene-propylene rubber (Tafmer P-0280 manufactured by Mitsui Petrochemicals)
5 parts by weight, BHTo. 1 part by weight, Irganox 1
01 0 0.1 parts by weight, calcium stearate 0
．． 1 part by weight and 0.08 part by weight of the peroxide used in Example 1, and in the same manner as in Example 1, modified polypropylene was prepared. 4) I did.

Comparative Example 1 - ethylene content 5.5% by weight, Melt Flow Ray 1-9
．． BH to 100 parts by weight of powder of crystalline ethylene-propylene broth copolymer with
T 0. 1 part by weight, Irganox 1 0 1
The fracture energy was measured in the same manner as in Example 1, and the results are shown in Table 1.

Claims (1)

[Claims] A method of mixing a crystalline ethylene-glopyrene bronoch copolymer having a melt 70 rate of 3 to i5f'/1o with an organic peroxide and heat-treating the mixture. Melt flow rate of crystalline ethylene-propylene broth copolymer before heat treatment M F RA! 7'1o minutes. Melt of modified polypropylene obtained by heat treatment 7C
1-v Itowo MFR” 7710 minutes Tosult 1ogMF
yc ia so that RB/log MF RA is 1.25 to 5.0. A modified polypropylene with improved moldability and impact resistance, characterized in that it is obtained by heat treatment at ~00°C.