JP2004224018A - Soft resin material for multicolor injection molding improving adhesiveness on interface between rigid resin material and soft resin material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a adhesiveness at the interface between two materials in a multicolor injection molding of a material comprising a polyolefinic based rigid resin and an elastomer soft resin. <P>SOLUTION: The adhesiveness at the interface between two materials is improved by giving a high compatibility to a PP in the polyolefinic rigid resin and an EP rubber component by saturating a double bond of at least 60 % in a conjugated diene part in an SEBS to be used as the elastomer soft resin. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor injection-molded part for the interior and exterior of an automobile, and more particularly to a dashboard, a door trim and a floor console of an automobile requiring a soft touch, and a seat shield requiring a deformable function. Trim etc.
[0002]
2. Description of the Related Art Among multicolor injection moldings in which different materials are molded simultaneously or successively, a combination of materials most frequently used for automobiles has a polyolefin resin and a soft resin material on a hard resin material side. Is a polyolefin-based thermoplastic elastomer. However, this polyolefin-based thermoplastic elastomer needs to incorporate a large amount of a plasticizer (hereinafter referred to as an oil component) into the material for reasons such as softening and cost reduction. Therefore, when multicolor injection molding is performed, this oil precipitates at the bonding interface with the hard resin layer, and this causes a problem that the adhesive strength between the two materials is reduced. In addition, there are also problems such as stickiness of the surface due to precipitation on the surface of the molded product and deterioration of the scratch resistance, which impairs the merchantability.
[0003]
SUMMARY OF THE INVENTION An object of the present invention is to provide a soft resin material having no oil component in the material and having improved compatibility with a polyolefin resin which is a hard resin material. An object of the present invention is to provide a soft resin material which improves the adhesiveness to a hard resin material and is soft and excellent in scratch resistance by applying a simple substance or a blend material with a polyolefin resin.
[0004]
Means for Solving the Problems To achieve the above object, the polyolefin resin is made to have a saturation of the double bond of the conjugated diene portion of SEBS or SEBC (hereinafter referred to as "saturation") of 60% or more. And the adhesion at the interface between the two materials in multicolor injection molding.
[0005]
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist thereof.
A test piece shown in FIG. 1 was prepared using a two-color molding machine comprising two injection units, using polypropylene as a hard resin material and SEBS as a soft resin, and evaluating the joining strength. SEBS prepared several kinds from which the saturation of the double bond of a conjugated diene part differs. For comparison, a test piece prepared by applying a polyolefin-based thermoplastic resin having a Shore A hardness of 70 to the soft resin material was prepared. Both ends of these test pieces were gripped, stretched at a speed of 50 mm / min, and a load was applied to the joint interface to break the test piece. The quality of the adhesiveness was determined based on the following criteria.
：: 100% cohesive failure (hard resin material or soft resin material is broken)
△: Cohesive failure and interfacial fracture mixed ×: 100% interfacial fracture (peeling off at interface between hard resin material and soft resin material)
In the case of SEBS having different degrees of saturation, the adhesiveness to the hard resin material was improved from a point where the degree of saturation exceeded 40%, and stabilization was observed when the degree of saturation exceeded 60%. On the other hand, a remarkable improvement was observed for the polyolefin-based thermoplastic resin. FIG. 2 shows the evaluation results.
[Brief description of the drawings]
FIG. 1 is a diagram of a test piece for evaluating adhesiveness.
FIG. 2 is a diagram of an evaluation result.

Claims (1)

A multicolor injection-molded article in which the following (A) is a hard resin material, and a composition comprising (A) 0 to 95% by mass and (B) 100 to 5% by mass is a soft resin material.
The composition may optionally contain various additives such as an antioxidant, a light-resistant material, a light stabilizer, and a reinforcing material such as talc.
(A) Polyolefin-based resin (b) A hydrogenated diene-based copolymer having a number average molecular weight of 50,000 to 700,000, wherein the double bond of the conjugated diene portion of the conjugated diene-based copolymer is saturated by 60% or more. For example, it refers to a styrene ethylene butadiene styrene block copolymer (hereinafter, referred to as SEBS) or a styrene ethylene butadiene olefin crystal block copolymer (hereinafter, referred to as SEBC).

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