JPS60223857A - Resin composition for molding - Google Patents

Abstract

PURPOSE:A resin composition for molding giving a painted, molded part with good paint adhesion only by top coating without priming, which contains an unsaturated polyester and a specified thermoplastic resin as a resin component. CONSTITUTION:A mixture, in a weight ratio of 8:2-6:4, of an unsaturated polyester (A), and a thermoplastic resin (B) comprising a blend (B1) of a vinyl acetate polymer and an acrylic polymer in a weight ratio of 1:3-3:1 or a copolymer (B2) of vinyl acetate and an acrylic monomer in a weight ratio of 1:3-3:1 is mixed with about 70-180pts.wt., based on 100pts.wt. component A, crosslinking monomer (C) (e.g. styrene), a curing agent (D) (e.g. benzoyl peroxide), and a thickening agent (E) (e.g. magnesium oxide).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to molding resin compositions such as sheet molding compounds and bulk molding compounds.

[Prior art]

In recent years, the use of resin molded products has been increasing for the outer panels of automobile bodies due to their weight reduction, improved rust prevention performance, and increased design freedom. A sheet molding compound (hereinafter referred to as SMO) or a bulk molding compound (hereinafter referred to as BMO) is considered to be a suitable material because of its high hardness and good appearance.

SMQ and BMO generally contain unsaturated polyester, thermoplastic resin or elastomer (hereinafter referred to simply as thermoplastic resin), crosslinking monomers such as styrene, hardeners, thickeners, and fillers such as glass fibers. It is a sheet-like or block-like molding material used as a component.

In some cases, a one-coat paint system consisting of only a top coat has poor adhesion to the top coat, so a primer is used to ensure paint film adhesion, but the use of a primer increases costs accordingly. So I don't like it. In some cases, only a top coat is applied, but the paint film has poor adhesion, so it cannot be used as the outer panel of a car body. In addition, the surface of SMO and BMO molded products is sanded to improve the adhesion of the top coat.
This is also undesirable as it leads to an increase in costs.

[Purpose of the invention]

In view of the above-mentioned points, the object of the present invention is to provide SMQ, BMO, which can obtain sufficient paint film adhesion only by topcoating.
Our objective is to provide molding materials such as

[Structure of the invention,]

The present invention is a molding resin composition comprising (Al unsaturated polyester, (B) thermoplastic resin, (C) crosslinking monomer, (D) curing agent, (E) thickener, and CF) filler. (B) The acid component (B) is a blend of vinyl acetate polymer and acrylic monomer polymer, with a blend ratio of 1:6 to 6:1 (weight ratio, the same applies hereinafter). or (B2) a copolymer of vinyl acetate and an acrylic monomer with a copolymerization ratio of 1:6 to 3:1 (weight ratio, the same applies hereinafter), and (A) component. and (B
) The present invention relates to a molding resin composition characterized in that the ratio of components is 8:2 to 6:4 (weight ratio, the same applies hereinafter).

The present invention is based on conventional SIMO, EM (1!
It is characterized in that the above-mentioned specific blend or copolymer is used as the thermoplastic resin of the component (B), and this is used in the above-mentioned specific ratio with the unsaturated polyester of the component (A).

In the present invention, it has been found that the composition of the SMO1BMO composition and the type of thermoplastic resin as the component (B) have a large influence on coating adhesion.
B) Vinyl acid, polyacrylic acid ester, l-styrene, rubber, etc. have been used individually as the thermoplastic resin of component B), but when these are used alone, even if other compositions are adjusted, sufficient coating is not achieved. Membrane adhesion cannot be changed. However, unexpectedly, when a blend of a vinyl acetate polymer and a polymer of acrylic monomers in a specific ratio or a copolymer of these seven polymers in a specific ratio is used, (A)
It has been found that coating film adhesion can be improved even without the use of specially modified components.

1. However, in the case of the molding resin composition of the present invention, sufficient film adhesion can be achieved even if a top coat is applied without performing primer treatment, sanding treatment, etc. on the surface of the molded product, thereby reducing costs. It is possible to ensure the quality of the coating film while ensuring the same.

[Embodiments of the invention]

The unsaturated polyester of the +A+ component in the molding resin composition of the present invention is not particularly limited, and suitable results can be obtained using ordinary unsaturated polyesters.

For example, one type of unsaturated polybasic acid such as maleic anhydride and fumaric acid, or one type of unsaturated polybasic acid such as maleic anhydride and fumaric acid, or a saturated polybasic acid such as cifuric acid and isophthalic acid. Examples include unsaturated polyesters which are condensation products of a mixture of one or more basic acids and polyhydric alcohols such as ethylene glycol, propypyrene glycol, diethylene glycol, and neopentyl glycol.

In the present invention, as the thermoplastic resin of component (B), (
B) A blend of vinyl acetate polymer and acrylic monomer polymer, with a blend ratio of 1:5 to 6:
1, or (B2) a copolymer of vinyl acetate and an acrylic monomer, with a copolymerization ratio of 1:! 1~
It is necessary to use a ratio of 3:1. Excellent film adhesion can be achieved by using such specific blends or copolymers.

As the acrylic monomer polymer in component (B), (1) a polymer of acrylic ester and/or methacrylic ester, or (2) a polymer of acrylic ester and/or methacrylic ester and acrylic acid and/or ) and copolymers with melauric acid. The content of the acid component in the copolymer is 0.1 to
A range of 10% by weight is preferred.

The copolymer of vinyl acetate and an acrylic monomer as component CB2) includes (1) a copolymer of vinyl acetate and an acrylic ester and/or a methacrylic ester; or (2) a copolymer of vinyl acetate and an acrylic ester and/or a methacrylic ester. (or) methacrylic acid ester and acrylic acid and (
or) a copolymer with methacrylic acid. In the latter copolymer, it is appropriate that the proportion of the acid component be 1.1 to 10% by weight of the combined amount of the acrylic monomer.

Examples of the acrylic ester and methacrylic ester include lower alkyl esters having 1 to 2 carbon atoms.

When the blend ratio or copolymerization ratio of component (B) is outside the above range, the coating film adhesion is not sufficiently improved.

The ratio of component (A) to component (B) is 8:2 to 6:4.
It is necessary to be within the range of . If the ratio of component (A) to component (B) is outside this range, the improvement in coating film adhesion will not be sufficient. In addition, the molding shrinkage rate should be kept as low as possible.
For example, from the viewpoint of preventing molding defects such as sink marks and warpage by reducing the O, OX% or less, the ratio of the Al component to the (B) component is preferably in the range of 7:6 to 6:4.

Styrene is usually used as the crosslinking monomer of component (a). Component (0) is usually used in an amount of about 70 to 180 parts per 100 parts (heavy needle part, hereinafter the same) of the N component.

As the curing agent for component CD), organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, cyclohexanone peroxide, and cumene hydroperoxide are used. The curing agent is usually (A), (B
) and (a) 0.6 to 100 parts of the total amount of components
Approximately 3 copies are used.

Thickeners for component (E) include gold mrs oxides, hydroxides, and mixtures thereof of groups 1, 2, and 2 of the periodic table, such as magnesium oxide, magnesium hydroxide, calcium hydroxide, and calcium oxide, or calcium propionate. Examples include fatty acid gold tetrasalts such as , calcium laurate, and aluminum octoate. (E) Component is usually (
A.I.

Combination of components (B), (a), (D) and (F') ii1
It is used at a ratio of 0.01 to 1 part per 1100 parts of 'fi.

The filler of component (F) consists of fibrous and non-fibrous fillers, and glass fiber is usually used as the fibrous filler, but organic fibers, carbon fibers, etc. can also be used.

As the glass fiber, glass mat, glass cloth, chopped strand, etc. are used.

Examples of non-fibrous materials include calcium carbonate, mica, wollastenite, barium sulfate, talc, and kaolin. The fibrous filler and the non-fibrous filler are 20 to 200 parts and 80 to 80 parts, respectively, per 100 parts of the total amount of the (A)N, (B), (D), and (ln) components.
A proportion of 220 parts is used.

To make a molded product using the molding resin composition of the present invention, S
In the case of MO, if the desired number of sheets is desired, the bulk may be filled into a mold. Molding conditions are normal SM
O, it may be the same as in the case of BMC molding, for example, 50~
150k 9101112 pressure 1165~155°C
A certain degree of humidity is adopted.

For coating molded articles obtained from the molding resin composition of the present invention, a conventional top coating paint is used.

Since the molding resin composition of the present invention has excellent coating film adhesion, it can be suitably used as a molding material for automobile body outer panels, hoods, trunk lids, roofs, fender panels, skirt panels, and grille panels. Ru.

〔Example〕

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Examples 1 to 4 and Comparative Examples 1 to 2 A film with a thickness of 2 m was prepared using the SMO compositions shown in Table 1.
A test piece with a thickness of 5 mm was produced by laminating three sheets and press-molding them in a mold at 80kp10n2 and humidity of 140°C for 4 minutes.

acrylic urethane paint whose main ingredients are styrene and styrene) and baked at 80°C for 60 minutes to a thickness of 6.
A coating film of 0μ was formed.

The initial adhesion of the coating film, the adhesion after the water resistance test, and the adhesion after the weather resistance test were measured for the obtained painted test piece under the following conditions. The results are shown in Table 2.

(1) Measurement of adhesion Measurement was performed according to the square test method of J Engineering SD 0202 (8, 12). However, the inside of the rice was set at 2 mm.

(2) Water resistance test Painted test pieces were tested under standard conditions (temperature 20°C, humidity 50-60°C).
%R)I) for 72 hours, and then immersed in water at 40°0 for 240 hours. The measurement of adhesion after this test was carried out within one hour after the test piece was taken out of the water.

(8) Weathering test Outdoor Bakuro (south facing 35 degrees) was carried out for 12 months.

Note 1: Polycondensation of fumaric acid, turnip water 7, taric acid, ethylene glycol, and propylene glycol Special order 2 = Polycondensation of fumaric acid, isophthalic acid, propylene glycol, and neopentyl glycol Physical properties 3: Diameter 1
6μ, length 2.50m Table 2

Claims (1)

[Claims] 1 (A) unsaturated polyester, (B) thermoplastic resin,
A molding resin composition comprising (0) a crosslinking monomer, (D) a curing agent, (E) a thickener, and fF) a filler,
As component (B), a blend of vinyl acetate polymer and acrylic monomer polymer in a blend ratio of 1=6 to 3:1 (weight ratio), or (B)
2) A copolymer of vinyl acetate and an acrylic monomer with a copolymerization ratio of 1:6 to 6:1 (weight ratio) is used, and the ratio of components (A) and (B) is 8=2~6:
4 (weight ratio).