JPH04144745A - Coated molded form - Google Patents

Abstract

PURPOSE:To obtain a coated molded form having excellent adhesive properties by doubly molding a thermoplastic resin for an outer layer having a specific functional group to a polyamide resin molded form. CONSTITUTION:A thermoplastic resin for an outer layer having at least one kind or more of functional groups selected from a vinyl group, a carboxylic group, an epoxy group, a hydroxyl group, an amino group, a nitrile group, an acrylamide group, an isocyanate group, an acrylate group, an acryl group and an aldehyde group is doubly molded to a polyamide resin molded form, thus acquiring a coated molded form. Polystyrene, an ABS resin, polyethylene, polypropylene, etc., are cited as the thermoplastic resin employed for the doubly molded outer layer. The coated molded form having excellent water resistance and weather resistance can be obtained by using the thermoplastic resin or a thermoplastic resin composition. It is desirable that functional group content is employed within a range of 0.05-25wt.%, preferably 0.1-15wt.% to the thermoplastic resin for the doubly molded outer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coated molded product that provides an outer layer with excellent adhesion when double-molding a thermoplastic resin for an outer layer onto a polyamide resin molded product.

[Prior art] Polyamide resin generally has highly crystalline properties,
Therefore, when double molded into a polyamide resin molded article, the adhesion with the outer layer cannot be said to be good.

Polyamide resins are generally excellent in heat resistance, rigidity, strength, solvent resistance, and moldability, and have therefore come to be widely used in mechanical parts, electrical equipment, automobile parts, and the like.

However, polyamide resins usually have the disadvantage of poor water resistance and weather resistance.

In order to improve the above drawbacks, a method is known in which another thermoplastic resin having excellent water resistance and weather resistance is double molded on the surface of a polyamide resin molded product.

Generally, when double-molding a thermoplastic resin for the outer layer on a polyamide resin molded product, a known pretreatment method is to apply an adhesive or hot melt adhesive that has excellent adhesion to both resins to the surface of the polyamide resin molded product. It is being

However, these methods have many practical disadvantages, such as complicating the process and increasing costs.

[Problems to be Solved by the Invention] It is an object of the present invention to solve the problems of the prior art and to obtain a coated molded product that provides an outer layer with excellent adhesion to a polyamide resin molded product.

[Means for Solving the Problems] As a result of intensive studies, the present inventors have found that when double molding a polyamide resin molded product, it is better if the thermoplastic resin for the outer layer used has a specific functional group. The inventors have discovered that it is possible to obtain an outer layer with excellent adhesion, and have completed the present invention.

That is, the present invention provides polyamide resin molded articles with at least one group selected from vinyl groups, carboxyl groups, epoxy groups, hydroxyl groups, amino groups, nitrile groups, acrylamide groups, isocyanate groups, acrylate groups, acyl groups, and aldehyde groups. This invention relates to a coated molded product obtained by double molding a thermoplastic resin for an outer layer having more than one type of functional group.

Examples of the polyamide resin used in molding the polyamide resin molded article in the present invention include polyamide resins obtained by polycondensation of lactams or ω-amino acids having four or more membered rings, or polycondensation of dibasic acids and diamines. .
Examples of the lactam or ω-amino acid having four or more membered rings include ε-caprolactam, ω-laurolactam, ω-aminocaprylic acid, and ω-aminolauric acid.

Polyamides obtained from dibasic acids and diamines include geltaric acid, adipic acid, azelaic acid, sebacic acid,
From dibasic acids such as speric acid, dodecanniic acid, eicosionic acid, isophthalic acid, and terephthalic acid, and diamines such as tetramethylene diamine, hexamethylene diamine, octamethylene diamine, metaxylylene diamine, paraxylylene diamine, and paraphenylene diamine. The resulting polymer or copolymer can be exemplified.

Specific examples of the polyamides include nylon 4, nylon 6, nylon 12, nylon 66, nylon 610, nylon 612, polymethaxylylene adipamide, polymethaxylylene adipamide, polymethaxylylene dodecamide, polyhexamethylene Examples include, but are not limited to, phthalamide and mixtures or copolymers thereof.

In addition, the polyamide resin used in the present invention includes, in addition to the above-mentioned single polyamide resin, those blended with other thermoplastic/thermosetting resins, glass fibers, carbon fibers, mineral whiskers,
Formulated with one or more inorganic fillers such as calcium carbonate, talc, mica, and wollastonite, as well as stabilizers against deterioration caused by oxidation heat and ultraviolet rays, crystal nucleating agents, and plasticizers that are usually added to resin compositions. , antistatic agents, lubricants, etc. are also included.

Thermoplastic resins used for the outer layer of the double molding of the present invention include polystyrene, ABS resin, polyethylene, polypropylene, petroleum resin, vinyl chloride resin, acrylic resin,
Polyamide, vinyl acetate resin, polybutylene terephthalate, ethylene vinyl alcohol resin, ethylene vinyl acetate resin, polyacetal, polyphenylene ether,
Examples include phenoxy resin, polyurethane, thermoplastic elastomer, and thermoplastic resin compositions obtained by mixing these resins, but these resins and resin compositions may also contain glass fibers, carbon fibers, mineral whiskers, calcium carbonate,
1 inorganic filler such as talc, mica, wollastonite, etc.
It also includes those containing at least one type of stabilizer, a crystal nucleating agent, a plasticizer, an antistatic agent, a lubricant, etc., which are usually added to resin compositions to prevent deterioration due to heat of oxidation and ultraviolet rays.

By using the above thermoplastic resin or thermoplastic resin composition, a coated molded article with excellent water resistance or weather resistance can be obtained.

In the present invention, the functional groups used in the plastic resin for the outer layer are:
It is at least one selected from a vinyl group, a carboxyl group, an epoxy group, a hydroxyl group, an amino group, a nitrile group, an acrylamide group, an isocyanate group, an acrylate group, an acyl group, and an aldehyde group.

The above functional groups have a good affinity with the polyamide resin or react with the polyamide resin during molding, so the outer layer obtained by double molding has excellent adhesion to the inner layer polyamide resin molded product. .

°In addition, whether the above functional groups are directly chemically bonded to the thermoplastic resin for the outer layer by addition, grafting, polycondensation, etc., or whether the functional groups themselves are reacted, and whether substances containing these functional groups are blended. It doesn't matter what happens.

The content of these functional groups in the present invention is 0.05 to 25% by weight based on the thermoplastic resin for the outer layer to be double molded, preferably,
A range of 0.1 to 15% by weight is desirable.

When the functional group content is small, the effect of improving adhesion in double molding is small, and when it is too large, the effect of improving adhesion is not improved.

The coated molded article of the present invention is obtained by injection molding a thermoplastic resin for an outer layer on a molded article obtained by injection molding using a polyamide resin in a conventional manner.

[Actions and Effects of the Invention] By double-molding the polyamide resin molded product of the present invention with a thermoplastic resin for an outer layer having a specific functional group, a coated molded product with excellent adhesion can be obtained, and the polyamide resin molded product It becomes possible to add new functions to products.

[Examples] The present invention will be explained in more detail below using Examples and Comparative Examples.

The adhesion of the outer layer of the coated molded product obtained by double molding was evaluated based on T-peel strength.

That is, a 1/2" (12.7 mm) wide cut was made in the outer thermoplastic resin layer of a double-molded covering molded product, and the load (kg) when this outer layer was peeled off in the right angle direction was measured. , T peel strength.

Example 1 Poly(methaxylylene adipamide) manufactured by Mitsubishi Gas Chemical ■
pellets (1 g of polymer dissolved in 100 ml of 98% sulfuric acid, relative viscosity of 2.10 measured at 25°C) were injection molded at a mold temperature of 130°C and a molten resin temperature of 250°C. A rectangular molded product measuring 2"Xi/16" x 5" was obtained.

After installing this molded product in a mold with a shape of 1/2" x 1/8" x 5", the mold temperature was 50°C and the resin temperature was 230°C.
Maleic anhydride modified polypropylene (polypropylene 1
(obtained by reacting 00 parts by weight with 2 parts by weight of maleic anhydride) was injection molded.

The T-peel strength of the polypropylene outer layer of the obtained coated molded article was measured.

The results are shown in Table 1.

Example 2 A coated molded article was obtained in exactly the same manner as in Example 1 except that poly(ethylene vinyl alcohol) (hydroxyl group concentration in the resin = 15% by weight) was used instead of maleic anhydride-modified polypropylene.

Table 1 shows the results of measuring the T-peel strength of the outer layer.

Example 3 Except for changing the maleic anhydride-modified polypropylene in Example 1 to ethylene, ethyl acrylate, and maleic anhydride copolymer resin (blending weight ratio 28071515), all (
A coated molded article was obtained in the same manner. Table 1 shows the results of measuring the T-peel strength of the outer layer.

Example 4 In Example 1, the polyamide resin was changed to poly (hexamethylene adipamide) (manufactured by Toshi ■, product name: Amilan CM30).
01N), the mold temperature is 80 degrees, and the molten resin temperature is 27 degrees.
A coated molded product made of a maleic anhydride-modified ethylene/propylene copolymer (100 parts by weight of the copolymer was reacted with 1.5 parts by weight of maleic anhydride) in the same manner except that it was molded at 8 degrees Celsius). was obtained, and the T peel strength of the outer layer was measured.

Comparative Example 1 A coated molded product was obtained in exactly the same manner as in Example 1 except that the polypropylene was not treated, and the T-peel strength of the outer layer was measured. The results are shown in Table 1.

Table 1 Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Agent Patent Attorney Sadafumi Kohori

Claims (3)

[Claims] (1) At least one type of polyamide resin molded product selected from vinyl groups, carboxyl groups, epoxy groups, hydroxyl groups, amino groups, nitrile groups, acrylamide groups, isocyanate groups, acrylate groups, acyl groups, and aldehyde groups. A coated molded product obtained by double molding a thermoplastic resin for the outer layer that has a functional group. (2) A coated molded article characterized in that the thermoplastic resin for the outer layer used in claim (1) has a functional group concentration of 0.05 to 25% by weight. (3) A coated molded article according to claim (1), characterized in that an ethylene-propylene copolymer is used as the thermoplastic resin for the outer layer.