JP3404942B2 - Resin composition and molded article using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a resin composition mainly composed of a polycarbonate resin having an improved gas barrier property and having a good thermoplastic moldability, and a molded product using the same.

[0002]

2. Description of the Related Art Polycarbonate resins have excellent impact resistance, heat resistance and transparency and are widely used as engineering plastics. Further, due to its excellent characteristics, it is also used as a material for containers such as bottles. However, the polycarbonate resin has a large gas permeability to oxygen and carbon dioxide gas, and the storage performance for the contents deteriorated by the permeation of these gases is not satisfactory. For the purpose of reducing the gas permeability of the polycarbonate resin and improving the content storability, a method of forming a laminated structure with a gas barrier material having a low gas permeability such as saponified ethylene-vinyl acetate copolymer has been proposed. . However, in order to obtain a laminated structure, an adhesive resin is usually required between the polycarbonate resin and the gas barrier material, and a special molding device for laminating these plural materials is required, which complicates the manufacturing process. Is not preferable.

In order to improve the gas barrier performance of the polycarbonate resin, blending with a material having a small gas permeability, for example, a saponified ethylene-vinyl acetate copolymer is considered. Generally, the polycarbonate resin is a compound having a hydroxyl group. It is known that when they are mixed with each other at a high temperature, a chemical reaction is caused to cause a remarkable decrease in physical properties, and it is considered not preferable to blend a saponified ethylene-vinyl acetate copolymer with a polycarbonate resin.

Further, the polycarbonate resin has a relatively large viscosity and is insufficient in fluidity during melt molding, and
Since it is an amorphous resin and its viscosity is highly dependent on temperature, it is necessary to mold at a high temperature. As a method for improving this, blending with another material having excellent fluidity is widely performed.

As a partner polymer for blending for improving fluidity, for example, polyolefin such as polyethylene (PE), polypropylene (PP), polybutene, ethylene-
Styrene-based polymers such as vinyl acetate copolymer (EVAc), ethylene-propylene copolymer (EPR) and other rubber-like polymers, polystyrene (PS), high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS), etc. , Polyethylene terephthalate (P
A large number of polyesters such as ET) and polybutylene terephthalate (PBT) have been investigated, and many of them have already been put to practical use. However, any of these blends has a small effect of improving the gas barrier performance.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a resin composition improved in gas barrier performance of a polycarbonate resin and thermoplastic molding processability, and a molded article using the same.

[0007]

Means for Solving the Problems The present inventors have selected an ethylene-vinyl acetate copolymer saponified product which is considered to be unsuitable as a blending partner for a polycarbonate resin, and as a result of diligent examination of the blending ratio and blending conditions, Weight ratio of the saponified ethylene-vinyl acetate copolymer in the range of 1 to 30% by weight of the blended ratio of the saponified ethylene-vinyl acetate copolymer in the blend of the polycarbonate resin and the saponified product of the ethylene-vinyl acetate copolymer. X
(%) Solves the above problems by performing thermoplastic molding by melt-blending under the condition that the resin temperature T (° C.) does not exceed T = 0.5x + 260.

The ethylene content of the saponified ethylene-vinyl acetate copolymer used in the present invention is preferably in the range of 20 to 60 mol%. Ethylene content 20
When it is less than mol%, the thermoplastic moldability is poor, and when it is 60 mol% or more, the effect of improving the gas barrier performance is small. Further, as the polycarbonate resin used in the present invention,
Known polycarbonate resins can be used, but poly-4,4'-dioxydiphenyl-2,2 'propane carbonate is preferred.

Ethylene in the blend according to the invention
The blend ratio of saponified vinyl acetate copolymer is 1 to 30.
It is preferably in the range of% by weight. Blend ratio is 1
% Or less, the effect of improving the physical properties of the polycarbonate resin is small, and if it is 30% or more, the impact resistance and heat resistance, which are excellent properties of the polycarbonate resin, are remarkably deteriorated, which is not suitable for practical use.

In addition, the blending operation is performed by adjusting the weight ratio of the saponified ethylene-vinyl acetate copolymer in the blend to x (%).
The inventors have found that a good blended product and a molded product using the same can be obtained by melt-blending under the condition that the resin temperature T (° C.) does not exceed T = 0.5x + 260. In a temperature range exceeding this condition, the polycarbonate resin and the saponified product of the ethylene-vinyl acetate copolymer cause a chemical reaction and the blended product is significantly deteriorated.

The resin composition of the present invention may be used as a composite molded product in combination with other materials, if necessary. For example, polyethylene for the purpose of imparting water vapor permeability resistance,
For example, it is used as a container having a multi-layered structure with polyolefin such as polypropylene, or as a composite sheet with a polyester film having excellent non-adsorption of aroma components.

[0012]

In the present invention, by blending a saponified ethylene-vinyl acetate copolymer having a very low gas permeability with a polycarbonate resin having a high gas permeability, it is possible to improve the gas barrier performance with a relatively small amount of addition. It is possible. The blending method is the melt blending under the condition that the resin temperature T (° C.) does not exceed T = 0.5x + 260 when the weight ratio of the saponified ethylene-vinyl acetate copolymer in the blend is x (%) as described above. By doing so, a good blended product and a molded product using the same can be obtained.This is because the polycarbonate resin has a relatively large viscosity and the fluidity during melt molding is insufficient, and the viscosity of the amorphous resin is high. Since it is necessary to mold at a high temperature of about 280 ° C. or higher due to its high temperature dependency, it is necessary to blend a saponified ethylene-vinyl acetate copolymer having good fluidity to obtain fluidity at low temperature. It is thought that it has become possible to mold in such a temperature range because of the improvement in At the same time, the chemical reaction between the polycarbonate resin and the saponified ethylene-vinyl acetate copolymer can be suppressed by performing the blending operation and the molding in the above temperature range.

[0013]

EXAMPLES Next, the present invention will be described more specifically by way of examples.

<Example 1> Polycarbonate resin (Upilon S2000 manufactured by Mitsubishi Gas Chemical Co., Inc.) and ethylene-vinyl acetate copolymer saponified product having ethylene content of 29 mol% and saponification degree of 99% or more (Nippon Synthetic Chemical Industry ( Co., Ltd.
Soarnol D2908) or the same ethylene content 44 mol% (Soarnol A4412 by Nippon Synthetic Chemical Industry Co., Ltd.)
The blending conditions were evaluated by changing the blending ratio and the resin temperature during blending.

Pellet-shaped polycarbonate resin and saponified ethylene-vinyl acetate copolymer were mixed in a predetermined ratio sufficiently uniformly, and this was mixed with φ20 mm and L / D = 2.
6. A strand type die was attached to a full flight screw type single-screw extruder, the temperature of the resin was changed, and melt extrusion was performed to evaluate the degree of decomposition of the resin. The evaluation results are shown in Table 1.

[0016]

[Table 1]

Example 2 A polycarbonate resin (Upilon S2000 manufactured by Mitsubishi Gas Chemical Co., Inc.) and an ethylene-vinyl acetate copolymer saponified product having an ethylene content of 29 mol% and a saponification degree of 99% or more (Nippon Synthetic Chemical Industry ( Co., Ltd.
Soarnol D2908) with 95: 5, 90:10, 8
Mix well in a pellet state at a weight ratio of 0:20,
After melt-blending this with an in-line injection molding machine with a screw diameter of φ32 mm at a temperature at which decomposition does not occur,
The body was molded into a cup shape having a thickness of 0.8 mm and a capacity of 180 ml, and the oxygen permeability was measured according to the method of JIS K7126. For comparison, a container of a single polycarbonate resin was molded and the oxygen permeability was measured in the same manner.

[0018]

[Table 2]

[0019]

According to the present invention, when the saponified product of the ethylene-vinyl acetate copolymer is blended with the polycarbonate resin, the saponification of the ethylene-vinyl acetate copolymer is carried out under the temperature condition depending on the weight ratio of the saponified product of the ethylene-vinyl acetate copolymer. It is possible to obtain a resin composition having improved gas barrier performance of a polycarbonate resin and thermoplastic molding processability, and a molded product obtained by thermoplastic molding using the same.

Claims (3)

(57) [Claims] 1. A thermoplastic polymer (A) having a carbonate bond in its main chain (99 to 70% by weight) and an ethylene content of 20.
To 60 mol%, saponified ethylene-vinyl acetate copolymer (B) having a saponification degree of the vinyl acetate component of 90% or more (B) 1 to 30
A resin composition comprising a blended product in an amount of 1% by weight, where the resin temperature T (° C) does not exceed T = 0.5x + 260 when the weight ratio of (B) in the resin composition is x (%). A resin composition characterized by being melt-blended in. 2. A thermoplastic polymer having a carbonate bond in the main chain is poly-4,4'-dioxydiphenyl-2,
The resin composition according to claim 1, which is 2'propane carbonate. 3. A molded article formed by thermoplastic molding using the resin composition according to claim 1 or 2, wherein the weight ratio of the saponified ethylene-vinyl acetate copolymer in the resin composition is adjusted. A molded product obtained by melt blending under the condition that the resin temperature T (° C.) does not exceed T = 0.5x + 260 when x (%).