JPS60125627A - Blow-molded container - Google Patents

Abstract

PURPOSE:To improve transparency and eliminate non-uniformity in thickness of the titled container, by making injection stretching blow molding of a random copolymer of propylene and alpha-olefin whose melt flow index is 4-50g/10min. CONSTITUTION:A container made of polypropylene is obtained by making injection stretching blow molding of copolymer which is a random copolymer of alpha- olefin and ethylene, 1-butene, 1-pentane and 1-hexene having propylene for their main ingredient and a melt flow index of 4-50g/10min. As for the molded container, a nucleating agent can be kept loaded to the same as transparency of the same becomes far favorable, and in this case, the nucleating agent of less than 1wt% is favorable to a propylene-alpha-olefin copolymer. In addition to the above, an anti-oxidizing agent, a ultraviolet absorbing agent, an antistatic agent, lubricant and a coloring agent can be added to.

Description

[Detailed description of the invention] This invention relates to a blow-molded container made of polypropylene resin.

Polypropylene resin has excellent heat resistance, chemical resistance, and safety and hygiene, and its blow-molded products also have excellent rigidity and impact strength, so it is widely used in food containers, detergent containers, medical containers, etc. However, since blow molded products have insufficient transparency, the reality is that they do not fully meet market demands for transparency.

Conventionally, known methods for improving the transparency of polypropylene resin include adding a nucleating agent and copolymerizing α-olefin with propylene, but these measures cannot be taken in normal blow molding. Even if it is done, it is difficult to obtain sufficient transparency.

In addition, in conventional blow molding,
The polypropylene resin used for this purpose has good rigidity and transparency, so its melt flow indenox (M
FI) is at most 4S'/10 minutes, especially 1
~2fI of about 710 minutes is often used.

On the other hand, in recent years, an injection stretch blow molding method has been developed, and blow molded products using this method have also been prototyped, but the reality is that a polypropylene resin blow molded container with sufficient transparency and no uneven thickness has not been obtained. .

The present inventors have achieved excellent transparency using the injection stretch blow molding method,
Polypropylene 11 also has no uneven thickness.As a result of studying to obtain a blow-molded container for clothing, it was found that if a propylene-α-olefin copolymer having a specific MFI is used as the polypropylene resin, a good blow-molded container can be obtained. We have finally arrived at the present invention.

That is, the present invention is a polypropylene container made by injection stretch blow molding a random copolymer of propylene and α-olefin, wherein the propylene-α-olefin random copolymer is melt flow intex 4 to soy/io.
This is a polypropylene resin blow molded container with improved transparency and no uneven thickness.

The propylene-α-olefin random copolymer used in the present invention is a random copolymer mainly composed of propylene with α-olefins such as ethylene, 1-butene, 1-pentene, and 1-hexene, and its JIS K-7210
It is desirable that the MFI measured under condition 14 is 4 to 50 f710 minutes. Furthermore, a copolymer with ethylene is particularly desirable because it provides good transparency. Furthermore, polyglopylene homopolymer has significant thickness deviation and poor moldability.

MFI of propylene-α-olefin random co-M composite
If it is less than 4f/1[] minutes, sufficient transparency cannot be obtained.

However, if the MFI exceeds 10, it is impossible to stably obtain a good container because the unevenness of thickness becomes significant.

In the present invention, a nucleating agent can be added because the transparency is further improved. In that case, it is appropriate that the amount is 1M or less relative to the propylene-α-olefin random copolymer.

Furthermore, antioxidant5. Ultraviolet absorber 1. Additives such as antistatic agents, lubricants, and colorants, as well as other cooking fats and elastomers may be added and blended.

The injection stretch blow molding method, which is the molding method of the present invention, is a molding method in which a bottomed parison is molded by injection molding, and then a product is obtained by pre-blowing, stretching temperature adjustment, and stretch blowing. A combination of mechanical vertical stretching using a rod and air blowing is performed. As a molding machine suitable for this molding method, for example, injection stretch blow molding machine manufactured by Nissei ASB Machinery Co., Ltd.: AS
B-50.

Examples include ASB-150, ASB-250, and ASB-650.

In the present invention, in order to obtain particularly excellent transparency, the following conditions are desirable when, for example, an injection stretch blow molding machine ASB-50 is used as the molding machine.

Injection molding temperature: 200-260℃ Pre-blow stretching ratio: 10-1.8 times vertically, 12-20 times horizontally
Double preliminary blow air pressure = 3~7 K9/7 Stretching temperature adjustment mold temperature = 90~140℃ Stretching blow Stretching ratio: Longitudinal 12
- 65 times, width 1.2 - 60 times stretching blow air pressure 4 - 20 Ky/cη The polypropylene blow container of the present invention contains polypropylene with a stabilizer, an antistatic agent, an ultraviolet absorber, and a coloring agent. After adding additives such as a nucleating aid, the body is usually manufactured to a thickness of 0.2 to 10 mm by the above-mentioned injection stretch blowing. Sword 1,
It has excellent transparency, heat resistance, and #r4 impact resistance, so it can be suitably used for tableware containers, detergent containers, baby food containers, toiletry containers, medical containers, etc. by utilizing these properties.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Incidentally, the body haze was measured using a haze meter manufactured by Nihon Juishoku Co., Ltd. according to the method described in JIS K-6714.

Example 1 Ethylene content 4% by weight as polypropylene pattern fat, M
A propylene-ethylene random copolymer having an FI of 15 g/10 minutes and containing a nucleation aid of 0.3 weight percent was molded using an injection stretch blow molding machine ASB-Nail under the following conditions to obtain a body diameter of 70 mm. A round bottle with a content of 500 lbs was molded.

Injection molding temperature = 220°C Injection molding mold temperature: 15°C Pre-blow stretching ratio: 1x length, $14x Pre-blow air pressure = 51<+n/crl Stretching temperature adjustment mold depth: 1
00°C Stretch blow Stretch ratio: 18 times vertical, 12 times horizontal Stretch Flow air pressure = 91 (ri/Cf1t') The weight of the obtained hotlet was 247, and it was a polypropylene blow-molded container with extremely excellent transparency. 1. The wall thickness of the body was 0.58 mm, the degree of haze was 31%, and the transparency when the liquid was added was also good.

Examples 2 to 4, Comparative Examples 1 to 3 In Example 1, propylene-α- having the ethylene content and M F I shown in Table 1 was used as the polypropylene resin.
A master bottle was molded in the same manner as in Example 1 except that an olefin copolymer was used.

Table 1 shows the performance of the obtained bottle.

Table 1 Reference Example 1 A bottle similar to Example 1 obtained by extrusion stretch blow molding using the propylene-ethylene random copolymer used in Comparative Example 1 had a body wall thickness (058 mm).
Although it was uniform, it was pale white and hazy, and its transparency was insufficient, with a haze level of 60%.

The extrusion stretch blow molding method is a molding method in which an extrusion-molded pipe is cut into a certain length to obtain a parison, which is then reheated in a stretching temperature chamber and then stretch-blown to obtain a product. .

patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Scope of Claims] A blow-molded container made of a polypropylene resin made by injection stretch blow-molding a random copolymer of 1 propylene and an α-olefin, the propylene-α-olefin random copolymer being Meltflow Indenox 4. ~50ft'
A blow-molded container made of polypropylene resin with improved transparency and no uneven thickness, characterized in that it has a thickness of 710 minutes. Claim 1 in which the 2α-olefin is ethylene
A blow-molded polypropylene resin container as described in Section 1.