JPH06270355A - Multilayered plastic container - Google Patents

Abstract

PURPOSE:To obtain a plastic container having superior surface glossiness and surface properties while keeping hygienic qualities, moisture resistance, and resistance to contents, such as superior resistance to chemicals. CONSTITUTION:In a multilayered plastic container provided with an outermost layer of a polypropylene random coplymer resin and one or more polyolefin resin layers inside the layer, the resin used for the outermost layer is a polypropylene random copolymer resin containing 0.5-3.0wt.% ethylene content, containing 500-2000ppm of a nucleating agent, and having a melt flow rate (JIS-K6758, unit; g/10min) of 40.0 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic plastic container, and more particularly to a multilayer plastic container having excellent gloss and surface properties.

[0002]

2. Description of the Related Art Conventionally, containers made of a single polyolefin resin such as polyethylene and polypropylene have been widely used from the viewpoints of sanitary characteristics, moisture resistance, content resistance such as excellent chemical resistance, and price. However, it has been conventionally pointed out that these containers have poor gloss and surface properties in terms of appearance.

As a measure against this, there is a method in which the container is multi-layered and a resin having a certain degree of gloss such as propylene homopolymer or ethylene-propylene random copolymer is used for the outer layer. When an ethylene-propylene random copolymer is used, one is ethylene-propylene random containing about 3 to 8% by weight of ethylene and having a melt flow rate (JIS-K6758, unit g / 10 minutes) of about 2.5. Conventionally, there has been a container in which a copolymer is arranged as an outer layer, but even such a container is not sufficient in terms of appearance, that is, surface glossiness.

[0004]

The present invention has been made in order to solve the problems of the prior art as described above, and has sanitary characteristics, moisture resistance, excellent chemical resistance, and other contents resistance. The object is to provide a plastic container having excellent surface gloss and surface property while maintaining the above.

[0005]

In order to solve the above problems, the present invention provides a multilayer plastic container in which a polypropylene random copolymer resin is used as the outermost layer, and one or more polyolefin resin layers are provided on the inside thereof. Melt flow rate (JIS-K6758, unit g / 10) in which the resin used for the outermost layer contains 0.5 to 3.0% by weight of ethylene and 500 to 2000 ppm of a nucleating agent.
Is a polypropylene random copolymer resin having a content of 40.0 or less.

Further, as an embodiment of the present invention, in the above-mentioned multi-layered plastic container, a multi-layered plastic container having a layer structure of at least two layers in which a recycled material comprising the multi-layered plastic container is added to the innermost layer, or the above-mentioned multi-layered plastic container Examples of the plastic container include a multilayer plastic container having a layer structure of at least three layers in which a recycled material composed of the present multilayer plastic container is added to the second layer from the innermost layer.

The multi-layer plastic container of the present invention is a multi-layer blow-molded container, a multi-layer injection-molded container, a cup made of a multi-layer sheet material, and other containers produced by forming a parison by stacking and extruding compressed air. Or it may be a packaging material.

The present invention will be described in detail below. The resin used for the outermost layer has a melt flow rate (JIS-K6758, unit g / 10 minutes) containing 0.5 to 3.0% by weight of ethylene and 500 to 2000 ppm of a nucleating agent. It is a polypropylene random copolymer resin of 40.0 or less.

As the nucleating agent used in the outermost layer, a fatty acid metal salt, a benzylidene sorbitol compound, an organic phosphoric acid metal salt or the like can be used.

The polyolefin resin used for the inner layer is a polypropylene resin such as a block copolymer or a random copolymer, a polyethylene resin belonging to a density region of about 0.85 to 0.97, such as an ultra-low density or a low density,
A linear low-density or high-density polyethylene resin can be used alone, a mixture of these resins, or a mixture of these resins and another polyolefin resin.

As a method for reducing the recycled material obtained by crushing the top flash and the bottom flash generated during the molding of the present plastic container to the present plastic container, the innermost layer or the outer layer thereof, the recycled material alone, or , Block copolymer, random copolymer polypropylene resin, 0.85-0.97
It can be used as a mixture with a polyethylene resin belonging to a density region of a certain degree.

[0012]

The multi-layered plastic container of the present invention has a content of 0.5 to 3.0% by weight of ethylene in the outermost layer in the multi-layered structure while maintaining the contents resistance such as hygienic properties, moisture resistance and excellent chemical resistance. Content of 500 to 2000 ppm of nucleating agent
By using a polypropylene random copolymer resin having a melt flow rate (JIS-K6758, unit g / 10 minutes) of 40.0 or less, excellent surface gloss,
It is intended to realize a plastic container having a surface property.

[0013]

【Example】

<Example 1> Using a multilayer blow molding machine having the following two screw extruders, the following resins were plasticized and extruded by an extruder to form a laminated parison through a blow head, and the parison was formed. Was sandwiched in a blow mold having a cylindrical bottle-shaped cavity with a capacity of 500 ml, the upper part of the parison was cut, and blow molding was performed using compressed air.

Screw diameter Temperature Molded product layer ratio Screw A 25 mm φ 210 ° C. 10% Screw B 50 mm φ 210 ° C. 90% Die head — 210 ° C.

Resin used Screw A: Contains 1.9% by weight of ethylene and 100% of benzylidene sorbitol compound as a nucleating agent.
Melt flow rate containing 0 ppm (JIS-K67
58, hereinafter referred to as MFR, unit g / 10 minutes) is 10.0
Random Polypropylene Copolymer Resin of Screw B: Ethylene-Propylene Block Copolymer Resin with MFR of 0.5

Example 2 Using a multilayer blow molding machine having the following two screw extruders, the following resins were plasticized and extruded by an extruder to form a laminated parison through a blow head. The parison with a capacity of 500 ml was sandwiched in a blow mold having a cylindrical bottle-shaped cavity, the upper part of the parison was cut, and then blow molding was performed using compressed air.

Screw diameter Temperature Molded product layer ratio Screw A 25 mmφ 210 ° C. 10% Screw B 50 mmφ 210 ° C. 90% Die head ─ 210 ° C.

Resin used Screw A: 1.9% by weight ethylene content, 100 benzylidene sorbitol compound as a nucleating agent
Polypropylene random copolymer resin with an MFR of 10.0 containing 0 ppm Screw B: A material in which an ethylene-propylene block copolymer resin with an MFR of 0.5 and a recycled material of this molded product were mixed at a ratio of 1: 1.

<Example 3> Using a multi-layer blow molding machine having the following three screw extruders, the following resins were plasticized and extruded by an extruder to form a laminated parison through a blow head. The parison with a capacity of 500 ml was sandwiched in a blow mold having a cylindrical bottle-shaped cavity, the upper part of the parison was cut, and then blow molding was performed using compressed air.

Screw diameter Temperature Molded product layer ratio Screw A 25 mmφ 210 ° C. 10% Screw B 50 mmφ 210 ° C. 80% Screw C 25 mmφ 210 ° C. 10% Die head ─ 210 ° C.

Resin used Screw A: Benzylidene sorbitol-based compound as a nucleating agent was added as an nucleating agent with an ethylene content of 1.9% by weight.
Polypropylene random copolymer resin having an MFR of 10.0 and containing 0 ppm Screw B: a material in which an ethylene-propylene block copolymer resin having an MFR of 0.5 and a recycled material of this molded product are mixed at a ratio of 1: 1 Screw C: Ethylene-propylene block copolymer resin with MFR of 0.5

<Example 4> Using a multilayer blow molding machine having the following three screw extruders, the following resins were plasticized and extruded by an extruder to form a laminated parison through a blow head. The parison with a capacity of 500 ml was sandwiched in a blow mold having a cylindrical bottle-shaped cavity, the upper part of the parison was cut, and then blow molding was performed using compressed air.

Screw diameter Temperature Molded product layer ratio Screw A 25 mmφ 210 ° C. 10% Screw B 50 mmφ 200 ° C. 80% Screw C 25 mmφ 190 ° C. 10% Die head ─ 210 ° C.

Resin to be used Screw A: Ethylene content of 1.9% by weight, 100 benzylidene sorbitol type compound as a nucleating agent
Polypropylene random copolymer resin with MFR of 10.0 containing 0 ppm Screw B: High density polyethylene resin with MFR of 0.5 and density of 0.95 and recycled material of this molded article 1:
Material mixed in 1 Screw C: High density polyethylene resin with MFR of 0.5 and density of 0.95

Comparative Example 1 Using a multilayer blow molding machine having the following two screw extruders, the following resins were plasticized and extruded by an extruder to form a laminated parison through the blow head. The parison with a capacity of 500 ml was sandwiched in a blow mold having a cylindrical bottle-shaped cavity, the upper part of the parison was cut, and then blow molding was performed using compressed air.

Screw diameter Temperature Molded product layer ratio Screw A 25 mmφ 210 ° C. 10% Screw B 50 mmφ 210 ° C. 90% Die head ─ 210 ° C.

Resin used Screw A: MF containing ethylene content of 1.9% by weight
R is 10.0 polypropylene random copolymer resin Screw B: MFR is 0.5 ethylene-propylene block copolymer resin

In each of the examples, the appearance of the molded product was good.

[0029] Note) Gloss is based on JIS Z8741 60 degree specular gloss.

[0030]

According to the method of the present invention, a plastic container having a good appearance, a good surface gloss, and various physical properties such as a drop impact at a low temperature was obtained.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideo Fukushima 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Yusuke Terauchi 1-5-1, Taito, Taito-ku, Tokyo Toppan Imprint Co., Ltd.

Claims (3)

[Claims] 1. A multi-layer plastic container comprising a polypropylene random copolymer resin as the outermost layer and one or more polyolefin resin layers provided inside thereof, wherein the resin used as the outermost layer is 0.5 to 3.0% by weight. Contains ethylene,
A multi-layer plastic container characterized by being a polypropylene random copolymer resin having a melt flow rate (JIS-K6758, unit g / 10 minutes) of 40.0 or less containing 500 to 2000 ppm of a nucleating agent. 2. The multilayer plastic container according to claim 1, which has a layered structure of at least two layers in which a recycled material comprising the multilayer plastic container is added to the innermost layer. 3. The multi-layer plastic container according to claim 1, wherein the recycled material of the multi-layer plastic container is added to the second layer from the innermost layer to have a layer structure of at least three layers.