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Injection molded body having excellent barrier property

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Injection molded body having excellent barrier property


An injection molded article comprising: (A) 10 to 60% by mass of a polyamide resin comprising a diamine unit 70 mol % or more of which is one or more m-xylylenediamine units and a dicarboxylic acid unit 70 mol % or more of which is one or more dicarboxylic acid units comprising a C4 to C20 α,ω-linear aliphatic dicarboxylic acid and isophthalic acid at a molar ratio of from 30:70 to 100:0; and (E) 40 to 90% by mass of a mixed polyolefin comprising (C) 40 to 100% by mass of a polyolefin and (B) 0 to 60% by mass of a modified polyolefin, wherein at least a part of the polyamide resin (A) is dispersed in a layered state.

Browse recent Mitsubishi Gas Chenical Company, Inc. patents - Chiyoda-ku, JP
Inventors: Kazunobu Sato, Katsuya Maruyama
USPTO Applicaton #: #20120263962 - Class: 4284769 (USPTO) - 10/18/12 - Class 428 
Stock Material Or Miscellaneous Articles > Composite (nonstructural Laminate) >Of Polyamide >Next To Addition Polymer From Unsaturated Monomer(s) >Polymer Of Monoethylenically Unsaturated Hydrocarbon

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The Patent Description & Claims data below is from USPTO Patent Application 20120263962, Injection molded body having excellent barrier property.

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CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims the benefits of priority to U.S. Ser. No. 13/252,302, filed Oct. 4, 2011, which is a continuation of and claims the benefit of priority to U.S. Ser. No. 12/446,111, filed Apr. 17, 2009, which is a national stage of International Application No. PCT/JP2007/070432, filed Oct. 19, 2007. The contents of these applications are incorporated herein by reference in their entireties. The International Application is based on and claims the benefits of priority to Japanese Patent Application Nos. 2006-284766, 2006-284767 and 2007-038070.

TECHNICAL FIELD

The present invention relates to injection-molded articles having excellent barrier property and appearance, etc., and more particularly to multilayer injection molded articles that are excellent in barrier property, appearance, delamination resistance, heat resistance, etc., and single-layer injection-molded articles that are excellent in barrier property, appearance, etc.

BACKGROUND ART

Injection molding has been widely spread and used in various applications such as mechanical parts, automobile parts, electric and electronic parts and containers for food and drugs because it is capable of producing molded articles having a complicated shape with a high productivity. In particular, containers for beverages, etc., have been frequently constructed from an injection molded article because a mouth portion of these containers is formed into an excellent threaded shape in order to ensure sufficient tightening of a cap thereon.

As the material for injection molding articles, there have been used various general resins including polyolefins such as polyethylene and polypropylene, polyesters and polystyrenes. Of these resins, polyolefins such as polypropylene have been extensively used in various applications such as containers because they are excellent in flowability and heat resistance upon molding as well as exhibit a light weight and a low moisture absorption and are available at low costs.

However, the polyolefins tend to be deteriorated in barrier property against gases such as oxygen and are, therefore, unsuitable as containers for preserving contents that are apt to be adversely affected by oxygen, etc., or as containers for food or drugs which are required to exhibit a good keeping property under severe environmental conditions such as high-temperature conditions. In consequence, there are disclosed methods in which a barrier material such as polyamides is blended in the polyolefins to improve a barrier property of the polyolefins (refer to Patent Documents 1 and 2).

These methods might improve a barrier property of the polyolefins to some extent. However, the barrier material to be blended must be dispersed in the polyolefins in a specific condition, so that the polyolefins tend to be improved in barrier property only to an insufficient extent. In addition, these methods also have such a problem that molded articles obtained from the resin mixture tend to have a poor appearance owing to the polyamides that are locally present near a surface thereof. More specifically, the method of the Patent Document 1 requires a biaxial stretch blow molding procedure, and the molded articles obtained without conducting the biaxial stretch blow molding procedure tend to be deteriorated in barrier property. Whereas, the Patent Document 2 discloses the composite molded article made of a polyolefin matrix and an amorphous polyamide in the form of a plurality of masses dispersed in the polyolefin, but is silent about crystalline polyamides and polyamides having a m-xylylene skeleton.

Upon producing a molded article having a multilayer structure including polyolefin layers and a barrier layer by injection molding method, since a material for the barrier layer exhibit no adhesion to the polyolefin layers, the molded article is required to have, for example, a structure having at least five layers, i.e., a layer structure of polyolefin layer/adhesive layer/barrier layer/adhesive layer/polyolefin layer. The production of the molded article having such a multilayer structure tends to be accompanied with difficulties in view of its structure and moldability and, therefore, has been rarely practiced from industrial viewpoints. In consequence, there is disclosed a method in which a polyolefin is compounded with a modified polyolefin to enhance adhesion of a polyolefin layer to a barrier layer and necessitate no adhesive layer therebetween (refer to Patent Document 3). The method of the Patent Document 3 improves adhesion between the polyolefin layer and barrier layer, but requires a large amount of the expensive modified polyolefin to ensure sufficient adhesion between these layers. In addition, this method has such a problem that the resulting molded article tends to be deteriorated in heat resistance owing to addition of the modified polyolefin thereto.

The present inventors have previously proposed the polyamide resin obtained by polycondensation of a diamine component containing 70 mol % or more of m-xylylenediamine and a mixed dicarboxylic acid component containing an α,ω-linear aliphatic dicarboxylic acid and isophthalic acid (refer to Patent Document 4). The polyamide resin exhibits an excellent barrier property. However, it has been still required that a multilayer injection molded article produced using the polyamide resin is further improved in delamination resistance. Patent Document 1: JP 2004-292037A Patent Document 2: JP 2005-8664A Patent Document 3: JP 2006-131275A Patent Document 4: JP 2004-352985A

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

An object of the present invention is to solve the above conventional problems encountered in containers obtained by injection molding, and provide a multilayer injection molded article that is excellent in barrier property, appearance, delamination resistance and heat resistance, as well as a single-layer injection molded article that is excellent in barrier property, appearance, etc., which is capable of being produced in an economically advantageous manner.

Means for Solving the Problem

As the result of extensive and intensive researches for achieving the above object, the present inventors have found that the object is suitably achieved by a multilayer injection molded article including a resin layer composed of a specific polyamide resin and a modified polyolefin or a resin layer composed of the polyamide resin, the modified polyolefin and the other polyamide resin as a barrier layer, or by an injection molded article in which the above specific polyamide resin is dispersed in a layered state in a mixed polyolefin. The present invention has been accomplished on the basis of the above finding.

Thus, the present invention relates to the injection molded articles as described in the following aspects.

1. An injection molded article with a multilayer structure including at least one layer of a barrier resin composition including (A) 10 to 70% by mass of a polyamide resin including a diamine constitutional unit 70 mol % or more of which is derived from m-xylylenediamine and a dicarboxylic acid constitutional unit 70 mol % or more of which is derived from a dicarboxylic acid containing a C4 to C20 α,ω-linear aliphatic dicarboxylic acid and isophthalic acid at a molar ratio of from 30:70 to 100:0; (B) 90 to 30% by mass of a modified polyolefin; and (C) 0 to 50% by mass of a polyolefin.

2. An injection molded article with a multilayer structure including at least one layer of a barrier resin composition including (A) 50 to 90% by mass of a polyamide resin including a diamine constitutional unit 70 mol % or more of which is derived from m-xylylenediamine and a dicarboxylic acid constitutional unit 70 mol % or more of which is derived from a dicarboxylic acid containing a C4 to C20 α,ω-linear aliphatic dicarboxylic acid and isophthalic acid at a molar ratio of from 30:70 to 100:0; (B) 2 to 45% by mass of a modified polyolefin; and (D) 2 to 45% by mass of a m-xylylene group-free polyamide (D).



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stats Patent Info
Application #
US 20120263962 A1
Publish Date
10/18/2012
Document #
13531825
File Date
06/25/2012
USPTO Class
4284769
Other USPTO Classes
International Class
32B27/08
Drawings
0



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