JPH03222706A - Manufacture of colored molding - Google Patents

Abstract

PURPOSE:To form a colored film superior in heat resistance, water resistance and adhesion on the surface of a molding by a method wherein a composition containing polyepoxide-polyacrylate, polymeric unsaturated monomer and a coloring pigment is cast into a mold where a thermosetting sheet molding compound or a bulk molding compound is heated and molded and heating and pressurization are performed. CONSTITUTION:A thermosetting molding compound or a bulk molding compound is heated and molded within a mold. A coating composition containing a mixed polyepoxide comprised of glycidyl ether type polyepoxide possessing at least three epoxy groups and glycidyl ether type polyepoxide possessing the two epoxy groups at 95:5-5:95 (weight ratio) and a vehicle ingredient consisting mainly of polyepoxide-polyacrylate which is a reaction product with acrylic acid or methacrylic acid and a coloring pigment is cast into a mold. Then a colored coating is molded on the surface of the foregoing molding by performing heating and pressurization.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a colored molded article having excellent heat resistance, hot water resistance, etc.

<Conventional technology and problems to be solved> In recent years, plastic materials have been used in place of materials such as metal, wood, and ceramics in a wide range of fields, including residential equipment such as kitchens and bathrooms, and electrical equipment such as motor housings. This is becoming more and more common. As such plastic materials, fiber-reinforced sheet molding compounds (SMC) and bulk molding compounds (BMC), which have good moldability and are excellent in mass production, are mainly used. .

Molded products made of these plastic materials are usually colored to give them an aesthetic appearance, but there are two methods of coloring: (a) using a colored plastic material in which a coloring pigment is mixed into the plastic material in advance, and (b) a method of using colored plastic materials. The method of painting colored paint on the surface of a molded article is known as a typical method.

However, method (a) requires compounding a large number of colored pigments, resulting in high costs, and the plastic composition needs to be changed each time the color is changed, making it necessary to manufacture a wide variety of molded products in small quantities. It is inappropriate for Furthermore, it is difficult to produce the desired subtle color, and holes, pinholes, etc. are likely to occur, resulting in problems such as poor appearance.

In addition, although the method (b) above solves the above problems to some extent, it requires various steps such as surface treatment, painting, and drying, which not only complicates the process but also requires equipment for each step. Furthermore, it is difficult to form a uniform coating on a molded article having a complicated shape, and the adhesion of the obtained coating is also insufficient.

The present inventors have discovered a method that solves the above-mentioned problems and forms a colored film with excellent heat resistance, hot water resistance, adhesion, etc. on the surface of a molded article by a simple means, and has arrived at the present invention. It is something that

Means for Solving the Problems> That is, the present invention provides: (1) A thermosetting sheet molding compound (hereinafter abbreviated as rsMcJ) or a bulk molding compound (hereinafter abbreviated as rBMCJ) in a molding mold. Heating and molding in a mold, (2) (i > glycidyl ether type polyepoxide having 3 or more epoxy groups and glycidyl ether type polyepoxide having 2 epoxy groups (95:5 ~
5:95) [weight ratio] mixed polyepoxide;
A coating composition containing a vehicle component mainly composed of polyepoxide-polyacrylate and a polymerizable unsaturated polymer, which are reaction products with acrylic acid or methacrylic acid, and (ii) a color pigment, is placed in the mold. The present invention relates to a method for manufacturing a colored molded article, comprising: injecting the molded article, and then (3) heating and pressurizing the molded article, thereby forming a colored film on the surface of the molded article.

The present invention will be explained in detail below.

SMCXBM, a plastic material used in the present invention
As for C, conventionally known ones can be used without any particular restrictions. Specifically, typical examples include thermosetting fiber-reinforced plastics having a matrix of unsaturated polyester resin, epoxy acrylate resin, phenol resin, epoxy resin, etc.

The coating composition used in the present invention contains as essential components a vehicle component (i) mainly composed of polyepoxide-polyacrylate and a polymerizable unsaturated monomer, a color pigment (ii), and a polymerization initiator, and is further modified as necessary. resin, filler,
Consists of a mold release agent and various other additives.

The polyepoxide-polyacrylate is produced by reacting polyepoxide with a stoichiometric equivalent of acrylic acid or methacrylic acid, as described in US Pat. No. 3,301,743 and US Pat. No. 3,373,075.

In addition, the above-mentioned "reaction product of mixed polyepoxide and acrylic acid or methacrylic acid" in the present invention refers to the above-mentioned 2.
Not only reaction products of mixtures of different types of polyepoxides and acrylic acid or methacrylic acid, but also glycidyl ether type polyepoxides having three or more epoxy groups (hereinafter referred to as
A reaction product of acrylic acid or methacrylic acid and a glycidyl ether type polyepoxide having two epoxy groups (hereinafter referred to as ``polyfunctional polyepoxide'') and acrylic acid or methacrylic acid.
It also includes products in which a reaction product of "functional polyepoxide" (abbreviated as "functional polyepoxide") and acrylic acid or methacrylic acid is produced separately and mixed afterwards.

In the present invention, the polyepoxide is preferably a polyfunctional polyepoxide with an epoxy equivalent of about 150 to 5000 and a bifunctional polyepoxide (95:5 to 5:95), preferably (85:15 to 30 nia 0) [weight ratio] A mixed polyepoxide is used. By using the above mixing ratio, it is possible to combine the excellent performance of multifunctional polyepoxide, such as heat deterioration resistance, heat discoloration resistance, hot water resistance, and chemical resistance, with the excellent performance of bifunctional polyepoxide, such as flexibility and adhesion. The synergistic effect results in a coating with excellent durability. If the proportion of the polyfunctional polyepoxide exceeds the above range, the resulting coating will be hard and brittle, and will easily peel off due to impact. On the other hand, if the amount is too small than the above range, heat resistance, chemical resistance, etc. will deteriorate, which is not preferable. Typical examples of the polyfunctional polyepoxide include phenol novolac type polyepoxide, orthocresol novolac type polyepoxide, dephenynolpropane novolac type polyepoxide, dicyclopentadienephenol type polyepoxide, glycidylamine type polyepoxide, etc. It is not limited.

Note that polyfunctional polyepoxide has three or more epoxy groups, and there is no particular upper limit, but considering the difficulty of unreacted epoxy groups remaining in the reaction with acrylic acid or methacrylic acid, up to about 5 epoxy groups are recommended. Appropriate.

Commercially available products of these polyfunctional polyepoxides include Epicote 154 and Epicote 155 manufactured by Yuka Shell Epoxy Co., Ltd.
, Epicort 181, Epicort 157S65, Epicort) 180562, Epicort) YL933, Epicort E-10313, Epicort) 1032, Epicort 60
4; An example is DCE400 manufactured by Sanyo Kokusaku Pulp Co., Ltd.

As the bifunctional polyepoxide, bisphenol A
Typical examples include alkyl bisphenol A polyepoxide, spirocyclic polyepoxide, bisphenol F polyepoxide, bisphenol S polyepoxide, naphthalene skeleton-containing polyepoxide, aliphatic polyepoxide, and bromine-containing bisphenol A polyepoxide. , but not limited to these.

These bifunctional polyepoxides include Epicort 807, Epicort 828, x Hicoat YX-4000, and Epicuron YX-7 manufactured by Yuka Shell Epoxy Co., Ltd.; Epiclon EXA 1514, x Pigron 830, and Epiclon EXA4032 manufactured by Dainippon Ink and Chemicals. Examples include DE732, DE736, DR542, etc. manufactured by Dow Chemical Company.

The polymerizable unsaturated monomer has a function as a viscosity modifier for the coating composition, and is blended in order to undergo radical polymerization with the polymerizable unsaturated group in the polyepoxide-polyacrylate to form a cured film.

Specifically, the polymerizable unsaturated monomers include styrene, α
- Methylstyrene, divinylbenzene, vinyltoluene; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate; ethylene glycol, diethylene glycol, trimethylolpropane Typical examples include functional group-containing monomers such as di- or tri-(meth)acrylate; (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, and glycidyl (meth)acrylate.

The ratio of polyepoxy dopo IJ7 acrylate and polymerizable unsaturated salt as a vehicle component is (30:TO
~95:5)C weight ratio] is suitable. In addition, if the amount of polymerizable unsaturated salt is added in excess of the above ratio,
Warpage may occur in the molded product due to volumetric shrinkage during polymerization and curing.
Adhesion tends to decrease due to shrinkage stress within the coating. On the other hand, if the ratio is too low, the viscosity of the coating composition will increase, the dispersibility of the color pigment described below will decrease, and the fluidity during injection into a mold will tend to decrease.

Further, it is appropriate that the total amount of polyepoxide polyacrylate and polymerizable unsaturated polymer as a vehicle component is 35 to 90% by weight in the coating composition.

As the coloring pigment, any pigment conventionally used for plastics or paints can be used without any particular restriction, as long as it does not adversely affect the curability of the film and is resistant to discoloration. Specifically, titanium oxide for the white type; benzidine yellow, titanium yellow, and Hansa yellow for the yellow type; molybdate orange, yellow lead, and benzidine orange for the seed yarn; quinacridone and maroon for the red type; chromium green and chromium oxide green for the marginal type; In the case of ultramarine, cobalt blue, ultramarine; in the case of black, powdered pigments such as carbon black, iron oxide, or flaky iron oxide,
Typical examples include scaly pigments such as mica treated with nickel, titanium oxide, etc. Note that the amount of color pigment is arbitrarily determined depending on its type. However, it is usually appropriate to incorporate it in an amount of 0.5 to 40% by weight in the coating composition.

The polymerization initiator generates free radicals and is used to polymerize the vehicle component. As a polymerization initiator, tertiary butyl perbenzoate, tertiary
Typical examples include butyl peroctoate, methyl ethyl ketone peroxide, tert-benzyl perbenzoate, dicumyl peroxide, cumyl hydroperoxide, diacetyl peroxide, prylyl peroxide, tert-butyl hydroperoxide and the like. The amount is 0.1-3 based on the vehicle component.
It is appropriate to add about % by weight.

The modifying resin, which is blended as necessary, is used to improve the dispersibility, in-mold fluidity, storage stability, etc. of the pigment, or to improve the flexibility, adhesion, curability, etc. of the resulting film. used for.

Modifying resins are broadly classified into non-reactive resins and reactive resins, mainly in terms of radical reactivity, but it is desirable that any of them be soluble or stably dispersed in the polymerizable unsaturated resin.

Non-reactive resins include polystyrene, polyvinyl acetate,
Polyvinyl acetate-acrylic copolymer, polyvinyl chloride,
Thermoplastic or thermosetting polymers such as polyvinyl chloride-vinyl acetate copolymer, polyvinyl chloride-acrylic copolymer, polyacrylate, polystyrene-butadiene copolymer, polyester, butyral resin, melamine resin, rosin, cellulose, etc. is mentioned as a typical example, and the amount can be blended up to about 30% by weight in the coating composition.

On the other hand, reactive resins include polyols having hydroxyl groups such as polyesters, polyacrylates, polybutadiene, polycarbonates, polyethers, polyalkylene glycols, etc., to which polyisocyanate is added, and (meth)acrylates are added to the terminals, or Urethane acrylate oligomer or urethane acrylate polymer, which is a reaction product of a compound having a hydroxyl group and a polymerizable unsaturated group with a polyisocyanate; a polymerizable unsaturated group in the main chain or side chain of an unsaturated polyester, diallylphthalate polymer, etc. Typical examples include polymers containing The amount thereof can be incorporated up to about 40% by weight in the coating composition.

In addition, the filler disperses the shrinkage stress caused by the hardening of the film, improves adhesion to the substrate, fills the many pores existing on the surface of the molded product, and smooths minute irregularities (wavyness) on the surface. It is added for the purpose of improving surface appearance.

Typical fillers include calcium carbonate, talc, barium sulfate, aluminum hydroxide, etc., each having a maximum particle size of 20 μm or less. The amount is 50% in the coating composition.
It is possible to mix up to about 10% by weight, preferably 15 to 40% by weight.

The release agent is added so that the cured film can be smoothly released from the mold, and its types include stearates such as zinc, aluminum, magnesium, and calcium, lecithin, and alkyl phosphates. is mentioned as a typical example, and the amount is 0 in the coating composition.
．． It is appropriate to mix 0.05 to 2% by weight.

Furthermore, various additives such as curing accelerators, dispersants, antisettling agents, flow aids, and polymerization inhibitors can be optionally added as the additives.

The coating composition used in the present invention consists of the components described above.

Next, a method for producing a colored molded article according to the present invention will be explained.

As the manufacturing method of the present invention, injection molding method, compression molding method, etc. can be used, but preferred are the methods described in Japanese Patent Application Laid-open No. 61273921 and Japanese Patent Publication No. 55-9291.

That is, by fitting one mold into the other mold (hereinafter, for convenience, the former is referred to as the "E lower mold" and the latter as the "upper mold"), a cavity having the shape of the desired molded product is formed. A plastic material is placed between the molds forming a space, and heated and pressurized within the fitting molds to melt the plastic material and cause a thermosetting reaction to mold it into the desired shape.

The heating temperature for molding is arbitrarily determined depending on the molding time, the type of plastic material, etc., but 130 to 200°C is usually appropriate, and the mold is set at this temperature before adding the plastic material to form a cured coating as described below. It is desirable to maintain this temperature until the temperature is obtained.

The molding pressure is arbitrarily determined depending on the heating temperature, type of plastic material, etc., but is usually 50 to 140 kg/c.
nf is appropriate.

The molding time may be until the thermosetting reaction of the plastic material is completely completed, but when the coating composition described below is injected,
It is sufficient if the curing is strong enough not to damage the shape of the molded product, and usually about 40 to 120 seconds is appropriate.

Next, the upper mold is separated from the surface of the molded product to provide a gap that is larger than the desired cured film thickness described below but insufficient to disengage the mold, or after the mold is fitted. or while maintaining the molding pressure in the state of 20 to 4
After reducing the pressure to about 0 kg/cnf, an amount of the coating composition to obtain a cured film with a desired film thickness, preferably 10 to 500 μm, is press-injected (injection injection) between the upper mold and the surface of the molded product. do.

Next, while maintaining the heating temperature at approximately the above-mentioned temperature, the coating composition is heated for approximately 20 to 20 minutes to uniformly cover and permeate the surface of the molded article.
Pressure is (re)applied to 140 kg/cnf and maintained for approximately 30 to 120 seconds until a cured film is formed. After a cured film is formed on the surface of the molded product in this manner, the mold is opened and the molded product is taken out, thereby obtaining the colored molded product of the present invention.

<Effects of the Invention> Since the method of the present invention performs everything from molding to forming a colored film in the same mold, there is no need for various equipment such as surface treatment equipment, painting equipment, drying ovens, etc., as in conventional methods. Since the manufacturing process is simple, costs and man-hours can be significantly reduced.

In addition, since the coating is formed under pressure, it penetrates into the minute pores on the surface of the molded product, resulting in a coating with good appearance such as smoothness.Furthermore, the specific coating composition mentioned above is used. Therefore, it is possible to obtain a film that has excellent heat resistance without deterioration or discoloration even when heat cycles are applied, and has excellent chemical resistance and adhesion.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the examples, "parts" and "%" are expressed on a weight basis.

Preparation of Coating Compositions A-J> The components shown in Table 1 (excluding the polymerization initiator) were kneaded and dispersed, and the polymerization initiator was added immediately before use to prepare coating compositions A-J.

Examples 1 to 6 and Comparative Examples 1 to 4 Molded articles having coatings were manufactured under the following conditions according to the molding apparatus and molding method described in JP-A-61-273921.

Using a chrome-plated box-shaped test mold with a length of 250 mm, a width of 150 mm, and a height of 50 mm, the molding temperature was set to the upper mold 1.
The temperature was set at 50°C and the lower mold temperature was 145°C.

First, a heat-resistant unsaturated polyester thermosetting glass fiber reinforced plastic (glass fiber content 30%) is placed on the lower mold.
350g of SMC material was set, and the molding pressure was 130k.
It was molded under the conditions of g/cut and molding time of 50 seconds.

Next, after reducing the molding pressure to 30 kg/cnf, 25 g of each coating composition was injected between the upper mold and the molded article, and the molding pressure was again increased to 70 kg/cut and maintained for 90 seconds.

Then, the mold was opened and the molded product was taken out. As a result, a molded article covered with a colored film (film thickness: 120 μm) was obtained.

Various tests were conducted on the obtained film. The results are shown in Table 2.

As is clear from Table 2, the coating obtained by the method of the present invention has excellent adhesion, heat resistance, heat cycle resistance, boiling water resistance,
The impact resistance was also good.

On the other hand, in Comparative Examples 1 to 4, in which a mixed polyepoxide of a polyepoxide with three or more epoxy groups and a polyepoxide with two epoxy groups was not used as the polyepoxide-polyacrylate, all of them had poor heat resistance, heat cycle resistance, etc. It was unsuitable for colored molded products for applications requiring heat resistance.

Claims (1)

[Claims] A method for producing a colored molded article, comprising: (1) heating and molding a thermosetting sheet molding compound or a bulk molding compound in a mold; (2) (i) ) Glycidyl ether type polyepoxide having three or more epoxy groups and glycidyl ether type polyepoxide having two epoxy groups (95:5 to 5:
95) A vehicle component whose main components are polyepoxide-polyacrylate and a polymerizable unsaturated monomer, which are the reaction products of a mixed polyepoxide consisting of [weight ratio] and acrylic acid or methacrylic acid, and (ii) a colored pigment. A method characterized by forming a colored film on the surface of the molded article by injecting a coating composition containing the mold into the mold, and then (3) heating and pressurizing the molded article.