JPS6140532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding method for obtaining a composite consisting of an olefinic thermoplastic elastomer and a polyamide resin.

Olefin-based thermoplastic elastomers, which have rubber-like properties without being vulcanized, can be applied to conventional plastic molding methods, and are used in various industrial rubber products such as shock absorbers and vibration isolators in place of vulcanized rubber. There is a lot going on. Many of these industrial rubber products are often used in the form of a composite body using a rigid body such as metal or plastic as a base material, core material, attachment material to other members, etc. In particular, polyamide resins are often selected as plastics due to their mechanical or chemical properties.

Therefore, composites made of olefinic thermoplastic elastomers and polyamide resins are important industrial rubber products, but in such cases, strong bonding is often required at their interfaces. Conventionally, methods such as screwing, caulking, and adhesive bonding have been used, but items joined using these methods are
All of these methods have problems in terms of strength or cost at the joint, and are unsatisfactory.

Furthermore, insert molding is an important joining method, but even if a polyamide resin molded product is inserted and olefin elastomer is injection molded, the molding temperature of the general olefin elastomer is lower than the melting point of polyamide resin. without joining,
Furthermore, if the molding temperature is made higher than the melting point of the polyamide resin, deterioration of the olefin thermoplastic elastomer will be accelerated, which is undesirable.

The present inventors have conducted intensive research to develop a method for inserting a polyamide resin molded product into an olefin thermoplastic elastomer and achieving strong bonding at the interface. A film or sheet made of a thermoplastic polymer that can be melt-welded to both is inserted into a first mold, a polyamide resin is melt-welded to the film or sheet, and then the polyamide resin molded product is molded into a second mold. A strong bond can be obtained at the interface between the polyamide resin insert molded product and the olefin thermoplastic elastomer by inserting it into a mold and melting and press-welding the olefin thermoplastic elastomer to the film or sheet surface of the molded product. They discovered this and completed the present invention.

In the present invention, a sheet or film is first obtained by a molding method such as injection, extrusion, or compression from a thermoplastic polymer that can be melt-bonded to both an olefin elastomer and a polyamide resin, and then the film or sheet is molded by any method. The film or sheet is inserted into a first mold, and the polyamide resin is injection molded to melt and press the polyamide resin and the film or sheet.

At this time, the surface of the film or sheet is melted or softened by the thermal energy possessed by the polyamide resin in the molten state, and then the film or sheet is pressed by injection pressure. It is sometimes undesirable for the film or sheet to melt or soften and flow in the entire thickness direction before it is brought into close contact with the mold surface, which is required as the bonding surface between the polyamide resin molded article and the olefinic thermoplastic elastomer. That is, it is preferable that the film or sheet can be easily deformed to a large extent even if it has a complicated shape by the resin pressure of the polyamide resin melt. Therefore, the film or sheet is preferably made of, for example, a thermoplastic elastomer, and has a thickness of It can be determined as appropriate depending on the shape of the joint surface, but it is required to be 0.03 mm or more.

Next, the polyamide resin molded product with a film or sheet melt-pressed on a part of the surface is inserted into a second mold, and the olefin thermoplastic elastomer is injected or compression molded.
By melt-pressing the olefinic thermoplastic elastomer onto the film or sheet surface of the insert, the inserted polyamide resin molded product and the olefinic thermoplastic elastomer can be firmly bonded.

In this case, the molding temperature of the olefinic thermoplastic elastomer needs to be higher than the melting or softening flow temperature of the film or sheet. Further, the surface of the insert to be melt-pressed is preferably subjected to physical or chemical treatment such as plasma treatment, corona discharge treatment, flame treatment, oxidizing agent treatment, or the like. Melt pressure welding refers to bringing molten polyamide resin or olefin thermoplastic elastomer into pressure contact with a film or sheet made of thermoplastic polymer for a certain period of time, preferably 1 second or more, thereby bonding the two. This can be carried out during extrusion molding, compression molding or injection molding, but it is suitable for the present invention to carry out during injection molding.

The olefin thermoplastic elastomer in the present invention is a partially cured thermoplastic elastomer made of monoolefin copolymer rubber (e.g., EPM, EPDM) and polyolefin plastic (e.g., polyethylene, polypropylene), For example, it is something like Uniroyal's TPR, which is used as a filler.
It may also contain organic or inorganic fillers.

In addition, examples of the polyamide used in the present invention include nylon 6, nylon 66, nylon 6.10, and copolymers thereof, and naturally include those to which inorganic fillers such as glass fiber, calcium carbonate, and talc are added. It can be done.

Furthermore, the olefinic thermoplastic elastomer and polyamide may contain other commonly used additives such as stabilizers, antioxidants, heat resistant agents, molding aids, pigments, and weathering agents.

The thermoplastic polymer material that can be melt-welded to both the olefinic thermoplastic elastomer and the polyamide resin used in the present invention is one that melts or softens during molding of the olefinic thermoplastic elastomer and polyamide resin, and can adhere to the resin. That's fine. For example, a film or sheet of olefinic thermoplastic elastomer can also be used. Even if an olefin thermoplastic elastomer is injection molded by inserting a polyamide resin molded product, the molding temperature of the olefin thermoplastic elastomer is lower than the melting point of the polyamide resin, so joining is not possible, but the olefin thermoplastic elastomer film or sheet cannot be joined. is inserted into a first mold, and then a polyamide resin is injection molded to obtain a laminate of sheets.The laminate is inserted into a second mold, and an olefin resin is injected onto the polyolefin-based thermoplastic elastomer film or sheet. A laminate consisting of a polyamide resin/olefin thermoplastic elastomer film or sheet/olefin thermoplastic elastomer can be obtained by molding the thermoplastic elastomer. Other thermoplastic polymer materials include thermoplastic urethane elastomers, which are addition polymers consisting of soft segments and hard segments reacted with bifunctional polyols, glycols, and diisocyanates, and polystyrene-polybutadiene (or polyisoprene) block copolymers. Thermoplastic styrenic elastomers, ionomer resins made of partially ionically crosslinked polyolefin compounds, and ethylene-vinyl acetate copolymers are suitable, but essentially both polyamide resins and polyolefin elastomers can be melt-pressed. Any possible thermoplastic polymer material,
It is applicable to the present invention.

Examples of the present invention will be described below with reference to the drawings, but these are merely exemplary and can be modified and implemented as appropriate within the scope of the present invention.

A film 1 made of a thermoplastic polymer that can be melt-welded to both a polyamide resin and a polyolefin elastomer is held by air suction through the narrow groove 2 of the mold shown in FIG.
Insert into. Next, resin flow grooves 3, 4, 5
Polyamide resin is injected from the film, and one surface of the film is brought into contact with the molten polyamide resin. As a result, as shown in FIG. 2, the film 1 is brought into close contact with the mold surface, the void 7 is filled with the polyamide resin 8, and the film 1 and the polyamide resin 8 are melted and pressed together. After the polyamide resin has sufficiently cooled and solidified,
The mold was opened to obtain a polyamide resin molded product shown in FIG.

The molded product is then inserted into another mold as shown in FIG. 4, and a polyolefin elastomer 11 is injection molded through the resin flow groove 10.
The elastomer 11 is melt-pressed onto one side of the film of the insert molded product, and after the elastomer 11 is sufficiently cooled and solidified,
The mold was opened to obtain the molded product shown in FIG. The polyamide resin 8 and the olefin thermoplastic elastomer 11 were completely bonded via the film 1 made of a thermoplastic polymer.

This molded product was sufficiently practical as a bumper guard that could be attached to a bumper, which is a protective part of an automobile, with a single touch via the snap fit part 12.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of the mold, and are explanatory diagrams of the polyamide resin molding process. Figure 3 is a cross-sectional view of a polyamide resin molded product, and Figure 4 is a cross-sectional view of the mold. An explanatory diagram of the melt-pressing process of plastic elastomer, FIG. 5 is a sectional view of the product of the present invention.

Claims (1)

[Claims] 1. When insert molding a polyamide resin molded product into an olefinic thermoplastic elastomer, a film or sheet made of a thermoplastic polymer that can be melted and pressure bonded to both the olefinic thermoplastic elastomer and the polyamide resin is inserted into the first mold. After that, a polyamide resin is melt-welded to the film or sheet, the resulting molded product is inserted into a second mold, and an olefin thermoplastic elastomer is melt-welded to the film or sheet surface of the molded product. Features: Insert molding method for polyamide resin molded products into olefin thermoplastic elastomer.