JP3008773B2 - Multilayer plastic container - Google Patents

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 Heretofore, containers made of a single polyolefin resin such as polypropylene have been widely used from the viewpoints of sanitary properties, moisture resistance, excellent physical properties such as excellent chemical resistance, and price. However, these containers have conventionally been pointed out as having a problem of poor gloss and surface properties in appearance.

As a countermeasure, there is a method in which a container is formed into a multilayer structure and a resin having good gloss and surface properties, for example, a polypropylene homopolymer, an ethylene-propylene random copolymer, or the like is used as an outer layer. In the case of using an ethylene-propylene random copolymer, in one case, ethylene is contained in an amount of 3 to 8% by weight.
Conventionally, there is a container in which an ethylene-propylene random copolymer having a melt flow rate (JIS-K6758, unit g / 10 minutes) of about 2.5 is disposed in an outer layer. However, the impact strength at the time of dropping at a low temperature and the surface gloss were not sufficient.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and has properties such as sanitary properties, moisture resistance, and excellent chemical resistance. An object of the present invention is to provide a plastic container having excellent surface gloss and surface properties while maintaining the impact strength of the container due to dropping.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a multi-layer plastic container comprising a polypropylene random copolymer resin as an outermost layer and one or more polyolefin resin layers provided inside thereof. The polypropylene random copolymer resin used for the outermost layer contains 0.5 to 2.0% by weight of ethylene and has a density of 0.94 g.
/ Cm ³ or less of polyethylene resin from 2.0 to 15.0.
% By weight, 500-3000 ppm of nucleating agent, ethylene /
Melt flow rate to which 2.0 to 30.0% by weight of an α-olefin copolymer resin is added (JIS-K6758,
This is a multi-layer plastic container which is a resin having a unit of g / 10 min (hereinafter, referred to as MFR) of 40.0 or less. Further, in a multilayer plastic container in which a polypropylene random copolymer resin is used for the outermost layer and one or more polyolefin resin layers are provided on the inner side, the polypropylene random copolymer resin used for the outermost layer is 0.5 to 2.0% by weight. % Of a polyethylene resin having a density of 0.94 g / cm ³ or less, 2.0 to 15.0% by weight, and a nucleating agent of 50%.
A multi-layer plastic container which is a resin having an MFR of 40.0 or less to which 0 to 3000 ppm of a propylene / α-olefin copolymer resin is added in an amount of 2.0 to 30.0% by weight.

According to an embodiment of the present invention, there is provided a multi-layer plastic container having at least two layers in which a recycled material comprising the multi-layer plastic container is added to the innermost layer. A multilayer plastic container having at least three layers in which a recycled material comprising the present multilayer plastic container is added to the second layer from the innermost layer.

The multilayer plastic container of the present invention is a multilayer blow-molded container, a multilayer injection-molded container, a multi-layer sheet-shaped cup, and other containers made by forming a parison by laminating extrusion and blowing compressed air into the parison. Or it may be a packaging material.

Hereinafter, the present invention will be described in detail. As the nucleating agent used for the outermost layer, a fatty acid metal salt, a benzylidene sorbitol compound, a metal organic phosphate, or the like can be used.

As the polyolefin resin used for the inner layer, a polypropylene resin such as a block copolymer or a random copolymer, a polyethylene resin belonging to a density range of about 0.85 to 0.97, for example, ultra-low density, low density,
It is possible to use a linear low-density or high-density polyethylene resin alone, a mixture of these resins, or a mixture of these resins with another polyolefin resin.

As a method of reducing the recycled material obtained by pulverizing the top flash and the bottom flash generated at the time of molding the present plastic container to the present plastic container, the innermost layer or the outer layer thereof is composed of the recycled material alone or It can be mixed with a polypropylene resin such as a block copolymer or a random copolymer, or a polyethylene resin belonging to a density range of about 0.85 to 0.97.

[0011]

The multilayer plastic container of the present invention has a hygienic feature.
While maintaining content resistance such as heat resistance, moisture resistance, and excellent chemical resistance.
The outermost layer in the multilayer structure has a polypropylene random
The polymer contains 0.5 to 2.0% by weight of ethylene
And the density is 0.94 g / cm ^ThreeThe following polyethylene resin
2.0 to 15.0% by weight, and a nucleating agent of 500 to 300
0 ppm, ethylene / α-olefin copolymer resin
Melt flow rate added 2.0 to 30.0% by weight
(JIS-K6758, hereinafter referred to as MFR, unit g / 1
0 min) is 40.0 or less, or the ethylene /
Instead of the α-olefin copolymer resin, propylene /
Using a resin composition to which an α-olefin copolymer resin is added
To maintain the impact strength of the container due to falling, etc.
Plastic containers with excellent surface gloss and surface properties
To gain.

The ethylene component contained in the polypropylene random copolymer is preferably 0.5% by weight or more. If the content is too small, it is meaningless as a random copolymer. There is a possibility that surface strength, which is an excellent property as a resin, may be impaired. When the amount of the low density polypropylene to be added is 2% or less, the effect of improving the impact strength is small, and the effect of improving the surface properties at the time of molding is also small. If the added amount of the polyethylene is too large, the surface glossiness of the molded article decreases, so it is necessary to consider the balance with the required glossiness.

Regarding the nucleating agent to be added, if the amount is too small, the effect of improving the glossiness is small, and conversely, 3000 ppm
If the addition amount exceeds the range, there is a great possibility that the moldability will be impaired due to bleed-out during molding.

Further, as the elastomer which is an ethylene / α-olefin or propylene / α-olefin copolymer resin, those used as ordinary resin modifiers can be used. When the amount is less than the above, the effect of improving the impact strength is small. On the contrary, when the amount exceeds 30% by weight, the excellent gloss and surface strength of the polyethylene random copolymer resin are reduced.

Further, in the case of the random polypropylene resin mixture used as the mixture used as the outer layer, if the MFR is too high, air escape during molding is deteriorated, and irregular appearance due to poor air escape occurs on the surface of the molded product. , M
FR is preferably 40 or less, more preferably 20 or less.

[0016]

【Example】

<Example 1> Using a multilayer blow molding machine having two screw extruders as described below, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. Was placed in a blow mold having a cylindrical bottle-shaped cavity with a capacity of 500 ml, and after cutting the upper part of the parison, 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 ２１０ 210 ° C.

Resin Screw A: A polypropylene random copolymer resin containing 1.9% by weight of ethylene and having a density of 0.87
Melt flow rate (JIS) in which 10.0% by weight of an ultra-low density polyethylene resin of g / cm ³ , 1000 ppm of a benzylidene sorbitol compound as a nucleating agent, and 5.0% by weight of an ethylene / α-olefin copolymer resin are added.
-K6758, hereinafter referred to as MFR, in units of g / 10 minutes) A polypropylene random copolymer resin mixture having a 10.0 screw B: an ethylene-propylene block copolymer resin having an MFR of 0.5

Example 2 Using a multilayer blow molding machine having the following two screw extruders, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, 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 Screw A: A polypropylene random copolymer resin containing 1.9% by weight of ethylene was added with a density of 0.87%.
g / cm ^{3 of} an ultra-low density polyethylene resin of 10.0 wt%, a benzylidene sorbitol-based compound as a nucleating agent of 1000 ppm, and a propylene / α-olefin copolymer resin of 5.0 wt% of MFR of 10.0 wt%. Screw B: Ethylene-propylene block copolymer resin with MFR of 0.5

Example 3 Using a multilayer blow molding machine having two screw extruders as described below, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed via a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, 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 Screw A: A polypropylene random copolymer resin containing 1.9% by weight of ethylene and having a density of 0.87
g / cm ^{3 of} an ultra-low-density polyethylene resin at 10.0% by weight, a benzylidene sorbitol compound as a nucleating agent at 1000 ppm, and an MFR containing 5.0% by weight of an ethylene / α-olefin copolymer resin at 10.0% by weight. Screw B: A material obtained by mixing an ethylene-propylene block copolymer resin having an MFR of 0.5 and a recycled material of the molded article in a ratio of 1: 1.

Example 4 Using a multilayer blow molding machine having the following three screw extruders, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, blow molding was performed using compressed air.

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

Resin used Screw A: A polypropylene random copolymer resin containing 1.9% by weight of ethylene and a density of 0.87
g / cm ^{3 of} an ultra-low-density polyethylene resin at 10.0% by weight, a benzylidene sorbitol compound as a nucleating agent at 1000 ppm, and an MFR containing 5.0% by weight of an ethylene / α-olefin copolymer resin at 10.0% by weight. Screw B: Ethylene-propylene block copolymer resin having an MFR of 0.5 and a recycled material of this molded article mixed at a ratio of 1: 1 Screw C: Ethylene having an MFR of 0.5 -Propylene block copolymer

Example 5 Using a multilayer blow molding machine having three screw extruders as described below, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, 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 screw A: A polypropylene random copolymer resin containing 1.9% by weight of ethylene was added with a density of 0.87%.
g / cm ^{3 of} an ultra-low-density polyethylene resin at 10.0% by weight, a benzylidene sorbitol compound as a nucleating agent at 1000 ppm, and an MFR containing 5.0% by weight of an ethylene / α-olefin copolymer resin at 10.0% by weight. Screw B: A high-density polyethylene resin having an MFR of 0.5 and a density of 0.95 and a recycled material of the molded article are as follows:
Screw C: High-density polyethylene resin with MFR of 0.5 and density of 0.95

Example 6 Using a multilayer blow molding machine having the following three screw extruders, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, blow molding was performed using compressed air.

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

Resin Screw A: A polypropylene random copolymer resin containing 1.8% by weight of ethylene was added with a density of 0.87%.
g / cm ³ , 8.0 wt% of ultra low density polyethylene resin, 3000 ppm of benzylidene sorbitol compound as a nucleating agent, and 20.5 wt% of ethylene / α-olefin copolymer resin, MFR 8.5 Screw B: Ethylene-propylene block copolymer resin having an MFR of 0.5 and a recycled material of this molded article mixed at a ratio of 1: 1 Screw C: Ethylene having an MFR of 0.5 -Propylene block copolymer

Example 7 Using a multilayer blow molding machine having the following three screw extruders, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed via a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, blow molding was performed using compressed air.

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

Resin screw A: A polypropylene random copolymer resin containing 1.2% by weight of ethylene was added with a density of 0.90.
g / cm ³ of a low-density polyethylene resin at 15.0% by weight, a metal nucleating agent as a nucleating agent at 1000 ppm,
A polypropylene random copolymer resin mixture having an MFR of 11 obtained by adding 1000 ppm of electrostripper EA and 20.0% by weight of an ethylene / α-olefin copolymer resin as an antistatic agent. Screw B: ethylene having an MFR of 0.5 A material in which a propylene block copolymer resin and a recycled material of the present molded article are mixed at a ratio of 1: 1 Screw C: an ethylene-propylene block copolymer having an MFR of 0.5

Comparative Example 1 Using a multilayer blow molding machine having one screw extruder as described below, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. The parison was inserted into a blow mold having a capacity of 500 ml and having a cylindrical bottle-shaped cavity. After cutting the upper part of the parison, 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: containing 2.5% by weight of ethylene;
Screw: B: ethylene-propylene block copolymer resin with MFR of 0.5

<Comparative Example 2> Using a multilayer blow molding machine having the following two screw extruders, the following resin was plasticized and extruded by an extruder, and a laminated parison was formed through a blow head. The parison was sandwiched in a blow mold having a cylindrical bottle-shaped cavity with a capacity of 300 ml, and after cutting the upper part of the parison, 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: polypropylene homopolymer having MFR of 0.5 Screw B: ethylene-propylene block copolymer resin having MFR of 0.5

The appearance of the molded article in each of the examples was good.

[0044] Note) Gloss is based on JIS Z8741 60 degree mirror gloss. Drop strength n = 10, each sample 10 times, 1.2m
Drop, 5 ° C.

[0045]

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

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yusuke Terauchi 1-1-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. Examiner Yurika Ashihara (58) Field surveyed (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 B65D 1/00-1/48 B29C 49/00-49/80

Claims (4)

(57) [Claims] 1. A multilayer plastic container having a polypropylene random copolymer resin as an outermost layer and one or more polyolefin resin layers provided inside thereof, wherein the polypropylene random copolymer resin used as the outermost layer is 0.5 to 2 parts. Containing 0.04% by weight of ethylene and having a density of 0.94 g
/ Cm ³ or less of polyethylene resin from 2.0 to 15.0.
% By weight, 500-3000 ppm of nucleating agent, ethylene /
Melt flow rate to which 2.0 to 30.0% by weight of an α-olefin copolymer resin is added (JIS-K6758,
A multilayer plastic container characterized by being a resin having a unit of g / 10 min (hereinafter, referred to as MFR) of 40.0 or less. 2. A multilayer plastic container having a polypropylene random copolymer resin as an outermost layer and one or more polyolefin resin layers provided inside thereof, wherein the polypropylene random copolymer resin used as the outermost layer is 0.5 to 2 parts. Containing 0.04% by weight of ethylene and having a density of 0.94 g
/ Cm ³ or less of polyethylene resin from 2.0 to 15.0.
A multi-layered plastic container having a MFR of 40.0 or less in which a nucleating agent of 500 to 3000 ppm and a propylene / α-olefin copolymer resin of 2.0 to 30.0% by weight are added. . 3. A multilayer plastic container having at least two layers, wherein a recycled material comprising the multilayer plastic container is added to the innermost layer in the multilayer plastic container according to claim 1. 4. The multilayer plastic container according to claim 1, wherein a recycled material composed of the multilayer plastic container is added to the second layer from the innermost layer and has at least three layers.