JP5026012B2 - In-mold coating composition and in-mold coating product using the same - Google Patents

Description

  The present invention relates to an in-mold coating composition and an in-mold coating product using the same. In particular, the present invention relates to, for example, compression molding, injection molding of thermosetting resins such as SMC and BMC, reaction injection molding (RIM molding) mainly composed of dicyclopentadiene, and heat such as ABS resin and polystyrene resin. The present invention relates to an in-mold coating composition used for injection molding, injection compression molding, and injection press molding of a plastic resin, and a molded product thereof.

  In recent years, many thermosetting resin molded products or thermoplastic resin molded products have been used for automobiles, weak electricity, building materials, and the like. The major drawbacks of compression-molded fiber reinforced thermosetting resin moldings are the burrows, surface undulations, and sink marks that require pre-treatment such as putty filling or sanding when painting is required. It is a surface defect and requires a lot of man-hours and costs.

  In order to solve such drawbacks, a low shrinkage in-mold coating composition is known (Patent Documents 1 and 2).

  However, in the in-mold coating compositions of Patent Documents 1 and 2, although there are some effects in improving surface waviness and sink marks due to glass fibers, there are burrows with a depth of about 200 to 300 μm or more The mold coating composition itself has a drawback that it is slightly shrinkaged or wrinkled in the coating film due to curing shrinkage of the coating composition itself or thermal shrinkage from curing at high temperature to cooling.

  In the case of a reaction injection molded product containing dicyclopentadiene as a main component, the curing shrinkage of the molding material itself is large, and the thick part of the molded product such as a rib or a boss has a large sink. In addition to not being able to cover the sink marks with the composition, there was a disadvantage that wrinkles occurred in the cured coating film in the mold coating composition on the ribs and bosses in some cases.

In the case of injection molding, injection compression molding and injection press molding of thermoplastic resins such as ABS resin, polystyrene resin and polypropylene resin, the molding material is plasticized to about 200 ° C. to 240 ° C. in an injection cylinder and then 60 ° C. to 80 ° C. It is molded by injection into a mold adjusted to about 0 ° C., and shrinkage due to resin cooling is large, and the thick part of the molded product such as ribs and bosses has large sink marks. The in-mold coating composition has a drawback that not only the sink cannot be obscured, but the coating film is sometimes wrinkled.
Japanese Patent Publication No.59-19583 JP-A-6-107750 Japanese Patent Laid-Open No. 11-300776 JP-A-8-258080 Japanese Patent Laid-Open No. 11-300776 JP 2002-249680 A JP 2003-137944 A JP 2003-138165 A

  The problems of the present invention are, for example, compression molding, injection molding of thermosetting resins such as SMC and BMC, reaction injection molding (RIM molding) mainly composed of dicyclopentadiene, and heat such as ABS resin and polystyrene resin. An object of the present invention is to ameliorate the above-mentioned drawbacks with regard to a composition for molding a low shrinkage inner coating used for injection molding, injection compression molding and injection press molding of a plastic resin and its molded product. In other words, it is possible to provide a coating composition that effectively fills burrows, undulations, sink marks, etc. generated on the surface of a resin molded product, and provides a smooth coating film, and further uses this in-mold coating composition. By doing so, it is easy and practical to provide an excellent coated molded product.

  As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be achieved by the following configurations, and have reached the present invention. That is, the present invention relates to the following inventions.

1. (A) an oligomer having at least two (meth) acrylate groups, or an unsaturated polyester resin, (B) an ethylenically unsaturated monomer copolymerizable with the component (A), (C) a polylactic acid resin compound, (D) An organic peroxide initiator is an essential component, and (A) / (B) = 70/30 to 30/70 (parts by mass), and (A) + (B) with respect to 100 parts by mass, In-mold coating composition, wherein component C) is 20 to 100 parts by mass and component (D) is 0.2 to 5 parts by mass.

  2. A thermosetting resin molded article or a thermoplastic resin molded article, which is coated with the in-mold coating composition described above.

  According to the present invention, it is possible to provide a coating composition that effectively fills burrows, undulations, sink marks, and the like generated on the surface of a resin molded product, and provides a smooth coating film. By using the composition, an easily and practically excellent coated molded article is provided.

  Hereinafter, the present invention will be described in detail.

  The in-mold coating composition used in the present invention includes (A) an oligomer having at least two (meth) acrylate groups, or an unsaturated polyester resin, and (B) ethylene copolymerizable with the component (A). (C) Cellulose-based resin compound or polylactic acid-based resin compound (D) Organic peroxide initiator as an essential component, and if necessary, an internal mold release agent, a color pigment , Pigments such as extender pigments and conductive pigments, oxides such as silica and alumina having a particle size of 0.1 μm or less, modified resins, antioxidants, ultraviolet absorbers, curing accelerators, various dispersants, antifoaming agents And other optional components.

[(1) (A) component]
Component (A) used in the in-mold coating composition of the present invention is an oligomer having at least two (meth) acrylate groups, or an unsaturated polyester resin.

[(1-1) Oligomer having at least two (meth) acrylate groups]
Examples of the oligomer having at least two (meth) acrylate groups include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, polyether (meth) acrylate, and silicon (meth) acrylate oligomer. And so on.

  The mass average molecular weight of these oligomers may vary depending on the type of the oligomer, but is generally about 300 to 10,000, preferably 500 to 5,000. The oligomer having the (meth) acrylate group preferably has at least 2, preferably 2-6, (meth) acrylate groups in one molecule.

[(1-1-1) Urethane (meth) acrylate oligomer]
The urethane (meth) acrylate oligomer as an oligomer used in the present invention includes, for example, (i) an organic diisocyanate compound, (ii) an organic polyol compound, and (iii) a hydroxyalkyl (meth) acrylate. For example, the OH ratio is 0.8 to 1.0, preferably 0.9 to 1.0. An oligomer having a large number of hydroxyl groups can be obtained by using excessive hydroxyl groups or using a large amount of hydroxyalkyl (meth) acrylate.

  Specifically, an isocyanate-terminated polyurethane prepolymer is obtained by reacting (i) an organic diisocyanate compound and (ii) an organic polyol compound in the presence of a urethanization catalyst such as dibutyltin laurate. Subsequently, the urethane (meth) acrylate oligomer can be produced by reacting (iii) hydroxyalkyl (meth) acrylate until almost the free isocyanate group is reacted. The ratio of (ii) the organic polyol compound and (iii) hydroxyalkyl (meth) acrylate is, for example, about 0.1 to 0.5 mol for the former with respect to 1 mol of the latter.

  Examples of the (i) organic diisocyanate compound used in the above reaction include 1,2-diisocyanatoethane, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane, hexamethylene diisocyanate, and lysine diisocyanate. , Trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, bis (4-isocyanatocyclohexyl) methane, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatoethyl) cyclohexane, 1,3-bis (isocyanatomethyl) benzene, 1,3-bis (isocyanato-1-methylethyl) benzene and the like can be used. These organic diisocyanate compounds can be used alone or as a mixture of two or more thereof.

  The organic polyol compound (ii) used in the above reaction is preferably an organic diol compound, for example, alkyl diol, polyether diol, polyester diol and the like. Examples of the alkyl diol include ethylene glycol, 1,3-propanediol, propylene glycol, 2,3-butanediol, 1,4-butanediol, 2-ethylbutane-1,4-diol, and 1,5-pentane. Diol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,4-cyclohexanediol, 1,4-dimethylolcyclohexane, 4,8-dihydroxy Typical examples include tricyclo [5.2.1.02,6] decane, 2,2-bis (4-hydroxycyclohexyl) propane and the like.

  The polyether diol as the organic diol compound can be synthesized, for example, by polymerization of aldehyde, alkylene oxide, glycol or the like by a known method. For example, polyether diol can be obtained by addition polymerization of formaldehyde, ethylene oxide, propylene oxide, tetramethylene oxide, epichlorohydrin or the like to alkyl diol under appropriate conditions. Examples of the polyester diol as the organic diol compound include esterification reaction products obtained by reacting saturated or unsaturated dicarboxylic acids and / or their acid anhydrides with excess alkyl diols, and alkyl diols. An esterification reaction product obtained by polymerizing hydroxycarboxylic acid and / or lactone which is an intramolecular ester thereof and / or lactide which is an intermolecular ester can be used. The organic diol compounds mentioned above may be used alone or in combination of two or more thereof.

  As said (iii) hydroxyalkyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. can be mentioned. In addition, the urethane (meth) acrylate oligomer as the oligomer used in the present invention is a compound having a (meth) acrylate group and a hydroxyl group in one molecule and an organic diisocyanate, and the NCO / OH ratio is, for example, 0. It can also be produced by reacting in the presence of a urethanization catalyst such as dibutyltin dilaurate at a ratio of .9 to 1.0.

[(1-1-2) Polyester (meth) acrylate oligomer]
The polyester (meth) acrylate as an oligomer used in the present invention can be produced, for example, by a reaction between a polyester polyol having a hydroxyl group at the terminal and an unsaturated carboxylic acid. Such a polyester polyol can be typically produced by esterifying a saturated or unsaturated dicarboxylic acid or an acid anhydride thereof with an excess amount of an alkylene diol. Typical examples of the dicarboxylic acid used include oxalic acid, succinic acid, adipic acid, phthalic acid, maleic acid and the like. Examples of alkylene diols that can be used include ethylene glycol, propylene glycol, butane diol, pentane diol, and the like. Here, as unsaturated carboxylic acid, acrylic acid, methacrylic acid, etc. can be mentioned as a typical thing, for example.

[(1-1-3) Epoxy (meth) acrylate oligomer]
The epoxy (meth) acrylate oligomer as an oligomer used in the present invention includes, for example, an epoxy compound and an unsaturated carboxylic acid as described above per carboxyl group equivalent, for example, 0.5 to It is used at a ratio of 1.5, and is produced by a ring-opening addition reaction of an acid to a normal epoxy group. As an epoxy compound used here, bisphenol A type epoxy, phenolic novolak type epoxy, etc. can be mentioned suitably, for example.

  The polyether (meth) acrylate as an oligomer used in the present invention can be produced, for example, by reacting a polyether polyol such as polyethylene glycol or polypropylene glycol with the aforementioned unsaturated carboxylic acid.

[(1-1-4) Silicon (meth) acrylate oligomer]
The silicon (meth) acrylate oligomer as an oligomer used in the present invention is produced, for example, by an esterification reaction between a hydroxyl group of an alcoholic siloxane compound and (meth) acrylic acid. Silicon (meth) acrylate oligomers are particularly excellent in light stability or light resistance, and are effective when used outdoors for a long period of time.

[(1-2) Unsaturated polyester resin]
On the other hand, in the present invention, the unsaturated polyester resin used as the component (A) is, for example, a reaction between an organic polyol and an unsaturated carboxylic acid by a known method, and, if necessary, a saturated polycarboxylic acid. Can be made to react. Typical examples of the organic polyol to be used include ethylene glycol, propylene glycol, triethylene glycol, trimethylolpropane, glycerin, bisphenol A, and the like. Moreover, as unsaturated polycarboxylic acid to be used, (anhydrous) maleic acid, (anhydrous) fumaric acid, (anhydrous) itaconic acid etc. can be mentioned as a typical thing, for example. As the component (A), the (meth) acrylate group-containing oligomer and an unsaturated polyester resin may be used in combination.

[(2) (B) component]
The component (B) used in the present invention is an ethylenically unsaturated monomer that can be copolymerized with the component (A).

  Examples of such ethylenically unsaturated monomers include styrene, α-methylstyrene, chlorostyrene, vinyltoluene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. , 2-ethylhexyl (meth) acrylate, ethylene glycol (meth) acrylate, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid Amides, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, ethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) Acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, triallyl isocyanurate, and the like as a representative.

  As the component (B), an ethylenically unsaturated monomer may be used alone, or a mixture thereof can be used. Moreover, as an ethylenically unsaturated monomer, the ethylenically unsaturated monomer containing hydroxyl groups, such as 2-hydroxyethyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate, is included as mentioned above.

  The mass ratio of the component (A) to the component (B) depends on the type of the compound used as the component (A) and the component (B), but usually the component (A): component (B) = 90. : 10-5: 95, preferably 80: 20-20: 80, more preferably 70: 30-30: 70. If it is this range, the coating composition which has a moderate hardening characteristic and viscosity will be obtained.

  Particularly, it is preferable that a part of the component (A) and / or the component (B) contains 3 to 8 (meth) acrylates. As the component amount of the three (meth) acrylate compounds, it is appropriate to use 10 to 80, preferably 15 to 60, more preferably 20 to 50 parts by mass in 100 parts by mass of (A) + (B). is there. If the amount of the three (meth) acrylate compounds is 10 parts by mass or more, the cured coating film of the coating composition has a small shrinkage and is excellent in smoothness and excellent adhesion to various plastic substrates. On the other hand, if it is 80 mass parts or less, since the cured coating film of a coating composition does not become hard too much, or adhesiveness with various plastics is not inhibited, it is preferable.

  The component amount of the 4 to 8 (meth) acrylate compounds is 5 to 50, preferably 10 to 45, more preferably 15 to 40 parts by mass in 100 parts by mass of (A) + (B). Is appropriate. When the amount of 4 to 8 (meth) acrylate compounds is 5 parts by mass or more, the cured coating film of the coating composition has small shrinkage, excellent smoothness, and excellent adhesion to various plastic substrates. Therefore, it is preferable. On the other hand, if it is 50 mass parts or less, since the cured coating film of a coating composition does not become hard too much, or adhesiveness with various plastics is not inhibited, it is preferable.

[(3) (C) component]
Component (C) used in the present invention is cellulose derivative nitrocellulose, acetyl cellulose, cellulose acetate butyrate, cellulose acetate propionate, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, methyl Resins such as hydroxypropyl cellulose and / or polylactic acid resins can be used. Particularly preferred are nitrocellulose, cellulose acetate butyrate, cellulose acetate propionate, and an amorphous polylactic acid resin having a weight average molecular weight of about 15,000 to 80,000 with a D-lactic acid concentration increased to about 20 mol%. can give.

  (C) The compounding quantity of a component is 10-100 mass parts with respect to a total of 100 mass parts of the said (A) and (B) component, Preferably it is suitable that it is 20-80 mass parts. When the blending amount of the component (C) is 10 parts by mass or more, the curing shrinkage of the coating composition can be reduced, and it is excellent in smoothness and does not hinder adhesion with various plastics, which is preferable. On the other hand, if it is 100 parts by mass or less, it is preferable because curing shrinkage of the coating composition is eliminated, excellent smoothness and excellent adhesion to various plastic substrates are obtained.

[(4) (D) component]
The component (D) used in the present invention generates free radicals and is used for polymerizing the components (A) and (B). As polymerization initiators, tertiary butyl peroxybenzoate, tertiary butyl peroxy 2-ethylhexanoate, tertiary amyl peroxy 2-ethylhexanoate, tertiary butyl peroxyisopropyl carbonate, lauroyl peroxide, tertiary Typical examples include libutyl oxylaurate and 1,1-bis (tertiary butyl peroxy) -3,3,5-trimethylcyclohexane.

  The blending amount of the polymerization initiator is suitably 0.2 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass in total of the components (A) and (B). is there. Within this range, the curing reaction is suitably exhibited.

[(5) Internal mold release agent]
In the present invention, a release agent is used to release the cured coating film smoothly from the mold. Examples of mold release agents include stearic acid, stearic acid such as hydroxystearic acid, zinc stearate, aluminum stearate, magnesium stearate, calcium stearate, soybean oil lecithin, silicone oil, fatty acid ester, fatty acid alcohol dibasic Examples include acid esters. The compounding amount of the release agent is 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass with respect to 100 parts by mass in total of the components (A) and (B). It is. Within this range, the mold release effect is suitably exhibited.

[(6) Pigment]
The in-mold coating composition of the present invention further includes various color pigments conventionally used for plastics and paints as conventional pigments, extender pigments, conductive pigments, and particles having a particle size of 0.1 μm or less as necessary. Oxides such as silica and alumina can be used in combination. Color pigments include, for example, white dioxide for titanium dioxide, yellow for benzidine yellow, titanium yellow, hansa yellow, orange for molybdate orange, hanzazine orange, red for quinacridone, and green for chrome. For green, phthalocyanine green, and blue, pigments such as carbon black and iron oxide can be used for phthalocyanine blue, cobalt blue, ultramarine, and black. As extender pigments, for example, calcium carbonate, talc, barium sulfate, aluminum hydroxide, clay and the like can be preferably mentioned. As the conductive pigment, for example, carbon black, graphite, zinc oxide, titanium dioxide or the like coated with a conductive metal oxide such as antimony oxide, carbon fiber, or the like can be used.

  The pigment colors the molded article to give it an aesthetic appearance, to improve the appearance of the surface of the molded article, to give the cured coating film conductivity for the purpose of preventing static charge, and to prevent the surface from being damaged.

[(7) Others]
In the in-mold coating composition of the present invention, various modified resins such as polyisocyanate, resin particles having a particle size of 0.1 to 30 μm, antioxidants, ultraviolet absorbers, curing accelerators are further included as necessary. Various additives such as a pigment dispersant and an antifoaming agent may be blended.

  The in-mold coating composition of the present invention is substantially free of solvent. It is preferable that the solvent substantially not be contained because the solvent vapor is not taken into the coating composition in the mold at the time of flowing in the mold, and pinholes are not generated, and the coating film does not become brittle. It is. In addition, “substantially free” means that, for example, even if included, it is at most less than 1% and substantially 0% of the mass of the coating composition. For example, when a polyisocyanate compound is used, it is important to use one that does not substantially contain a solvent.

[(8) Resin molded product]
As the synthetic resin molded product to which the in-mold coating composition of the present invention is applied, conventionally known various thermosetting molding materials and various thermoplastic synthetic resin molding materials can be used. Examples of the thermosetting molding material include SMC using unsaturated polyester resin, epoxy acrylate resin, phenol resin as a matrix, fiber reinforced plastic molding material called BMC, unsaturated polyester resin, epoxy acrylate resin, and epoxy resin as matrix. RTM molding materials, RIM molding materials using dicyclopentadiene, polyurethane and the like. Examples of the thermoplastic synthetic resin molding material include polystyrene resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene oxide resin, polyphenylene ether resin, polyamide resin, polyimide resin, polyvinyl chloride resin, polyvinyl acetate. Examples thereof include resins, polylactic acid resins, ASA resins, ABS resins, AES resins, ASA resins, and various alloy materials of these resins.

  An alloy material is a composite material in which the above-mentioned thermoplastic synthetic resin and one or more other polymers are physically mixed, and is generally understood as a material having a synergistic effect on the overall practical performance. ing. Such a thermoplastic synthetic resin is, for example, an ultraviolet absorber, an antioxidant, a release agent, an antistatic agent, a colorant, a flame retardant, a plasticizer, and a glass fiber so as to satisfy characteristics according to the use. Such as fiber reinforcing agents, inorganic fillers and the like can be contained.

[(9) Method for producing in-mold coated product]
Hereinafter, a configuration of a molding machine, a molding die, and a coating composition injection device for carrying out the method for producing an in-mold coated molded product of the present invention will be specifically described with reference to the drawings. Is not limited by such a specific molding machine, mold and coating composition injection apparatus.

  FIG. 1 shows an apparatus for performing a compression molding method using a glass fiber reinforced thermosetting molding material called, for example, SMC (sheet molding compound). As the molding method, a conventional method of molding in a mold can be used without any particular limitation. Preferably, the method described in JP-B-55-9291, JP-A-61-273921, etc. is used. it can.

  In the apparatus shown in FIG. 1, the upper mold 1 and the lower mold 2 of the split mold are molding mold members facing each other. The upper mold 1 and the lower mold 2 are respectively fixed to a movable platen 3 and a fixed platen 4 of the mold clamping device, and the movable platen 3 is configured to move forward and backward by a mold clamping cylinder 5. A split mold cavity 6 having a required shape can be formed by the upper mold 1 and the lower mold 2, and the cavity can be expanded in the direction of the surface of the in-mold molded product covered by the mold by moving the upper mold 1. . The surface to be coated in the mold may be one surface or two or more surfaces. Therefore, the extension of the cavity in the direction of the surface to be coated in the mold may be one direction or more than two directions. May be. The above glass fiber reinforced plastic molding material is put between the upper mold 1 and the lower mold 2, the mold clamping cylinder 5 is operated, and the upper mold 1 and the lower mold 2 are brought close to each other to make the molding material into the shape of the cavity. Mold and harden by applying clamping pressure.

  Further, in the apparatus shown in FIG. 1, an injector 7 having a shut-off pin 7A which is an injection means for the in-mold coating composition, a measuring cylinder 8 for supplying a predetermined amount of the in-mold coating composition to the injector 7, and A supply pump 9 for supplying the in-mold coating composition from the storage unit 10 to the measuring cylinder 8 is provided. Note that the measuring cylinder 8 is provided with a plunger regulator 8A for injecting the composition for in-mold coating.

At the time of molding, first, the clamping cylinder 5 is operated to separate the upper mold 1 from the lower mold 2, and the glass fiber reinforced plastic molding material is placed on the lower mold 2, and then the clamping cylinder 5 is operated, The upper mold 1 and the lower mold 2 are brought close to each other to mold the molding material into a cavity shape, and a mold clamping pressure is applied. This mold clamping pressure is usually ^{2 to} 15 MPa (20 to 150 kgf / cm ² ). The molding temperature is arbitrarily determined depending on the molding time, the type of molding material, etc., but usually 120 to 180 ° C. is appropriate. Before putting the molding material, the mold is set to the above-mentioned temperature in advance and described later. It is desirable to maintain the temperature until a cured coating is obtained.

  Next, at the stage where the molded product in the cavity is cured to the extent that it can withstand the injection pressure and flow pressure of the in-mold coating composition, the mold clamping pressure is maintained while maintaining the mold clamping pressure as it is. After lowering the pressure, or larger than the desired cured film thickness described below, the upper mold 1 is molded by a distance that does not cause the fitting between the upper mold 1 and the lower mold 2 to be released, preferably 0.2 to 5 mm. After separating from the surface of the product, the inner coating of the upper mold 1 and the mold of the molded product are transferred from the injector 7 in an amount sufficient to obtain a desired film thickness, preferably a cured film of 20 to 1,000 μm. Inject between the surface to be coated.

After injecting the composition for in-mold coating, the injection port is closed with the shut-off pin 7A, the mold clamping cylinder 5 is operated as necessary, and the mold clamping operation is performed, and the mold is formed on the surface of the molded product in the cavity 6 The inner coating composition is cured. In general, about 1 to 10 MPa (10 to 100 Kgf / cm ² ) (re) pressurization is performed so that the in-mold coating composition uniformly covers the surface of the molded product, and the pressure is usually about about until a cured film is formed. Hold for about 30-300 seconds. After the cured film is formed on the surface of the molded product in this way, the mold clamping cylinder 5 is operated, the upper mold 1 and the lower mold 2 are separated, and the molded product having the cured film is taken out from the mold.

  FIG. 2 shows an embodiment in the case of an injection molding method of a thermoplastic resin molding material. In FIG. 2, reference numeral 11 denotes a stationary platen of a mold clamping device of an injection molding machine, and 12 denotes a movable platen, each having a fixed mold part 13 and a movable mold part 14 which are molding members facing each other. The movable platen 12 is configured to be moved back and forth by the mold clamping cylinder 15. A cavity 16 having a required shape is formed at a fitting portion of the fixed mold part 13 and the movable mold part 14, and a molten or soft thermoplastic resin molding material is injected and filled into the cavity 16. And solidify. When the molten resin molding material is injected and filled, the resin molding material can be injected into the cavity 16 from an injection cylinder 17 having a screw through a nozzle 18 and a sprue 19. In FIG. 2, reference numeral 20 denotes a rib part (boss part) 21, which is an ejector pin at the time of mold release.

  Further, in FIG. 2, the injection means for the in-mold coating composition includes an injector 22 having a shut-off pin 22A, a measuring cylinder 23 for supplying a predetermined amount of the in-mold coating composition to the injector 22, and an in-mold coating. A supply pump 25 is provided for supplying the composition from the reservoir 24 to the metering cylinder 23. The measuring cylinder 23 is provided with a plunger regulator 23A for injecting the mold coating composition.

At the time of molding, first, the mold clamping cylinder 15 is operated to close the molds (the fixed mold part 13 and the movable mold part 14) and apply the mold clamping pressure. This clamping pressure needs to be able to counter the injection pressure of the resin molding material. Usually, this injection pressure is a high pressure of 40 to 250 MPa (400 to 2,500 Kgf / cm ² ) at the nozzle 18 portion. In this process, the supply pump 25 operates to supply a necessary amount of coating material to the measuring cylinder 23.

  Next, the molten or softened resin molding material is injected from the injection cylinder 17 into the cavity 16 through the nozzle 18 and the sprue 19. When the resin molding material is properly solidified in the mold (to the extent that it can withstand the injection pressure and flow pressure of the in-mold coating composition), the mold clamping pressure is reduced, or the desired cured coating described below. Although it is larger than the thickness, the movable mold part 14 is retracted by a distance that does not cause the fitting of the fixed mold part 13 and the movable mold part 14 to be released, preferably 0.2 to 5 mm. Next, the shutoff pin 22A is operated to open the injection port of the injector 22. Then, the plunger regulator 23A for injecting the in-mold coating composition of the measuring cylinder 23 is operated, and a desired space is formed between the cavity 16, that is, the inner wall of the fixed mold portion 13 and the surface of the resin molded product to be coated in the mold. An in-mold coating composition is injected in an amount sufficient to obtain a film thickness, preferably a cured coating of 20 to 1,000 μm.

  After injecting the in-mold coating composition, the injection port is closed again with the shut-off pin 22A, the mold clamping cylinder 15 is operated as necessary, and the mold clamping operation is performed. The surface of the molded product is diffused and coated, and the in-mold coating composition is cured on the surface of the molded product of the cavity 16. Next, the clamping cylinder 15 is operated, the fixed mold part 13 and the movable mold part 14 are separated from each other, and a molded product having a cured film is taken out from the mold.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, the scope of the present invention is not limited at all by these Examples and comparative examples.

[ Reference Examples 1-5, 8-11, Examples 6, 7 and Comparative Examples 1-5]
A mold having a cavity for obtaining a resin molded product having a box shape of 1000 mm in length, 500 mm in width, 30 mm in height, and 3 mm in thickness, and having a boss with an outer diameter of 15 mm, an inner diameter of 5 mm, and a height of 13 mm. In-mold coating was performed on the molded product according to the embodiment shown in FIG. In this case, the mold temperature is set to 150 ° C. for the upper mold and 140 ° C. for the lower mold. First, the SMC molding material is placed on the lower mold, clamped with a clamping pressure of 500 tons, and held for 90 seconds. The surface of the molded SMC product was cured to such an extent that it could withstand the injection and flow pressure of the in-mold coating composition. Next, after separating the upper mold by about 2 mm, 70 cm ³ of each of the in-mold coating compositions having the compositions shown in Tables 1 and 2 was injected between the mold surface and the surface of the molded article over about 5 seconds. did. After completion of the injection, the clamping pressure was increased to 300 tons over 1 second and held for 2 seconds. The mold clamping pressure was then reduced to 200 tons and held for 2 seconds, then the mold clamping pressure was reduced to 150 tons and held for 86 seconds to cure the in-mold coating composition. The appearance of the obtained molded product, the presence or absence of coating film wrinkles on the boss, and the adhesion of the in-mold coating composition were evaluated according to the following evaluation methods. The results are shown in Tables 3 and 4.

<Appearance of molded product>
The cured state of the coating film covering the surface of the molded product, bubble entrainment, coating film swelling, coating film peeling, and the like were visually observed and evaluated according to the following criteria.

○: Good for all △: Some defectives ×: Significant defects

<Presence / absence of wrinkles on the boss>
It observed visually and evaluated by the following reference | standard.

○: Wrinkle is not recognized at all △: Slightly wrinkled is observed ×: Wrinkle is remarkably recognized

<Adhesiveness>
According to JIS K 5600-5-6: Adhesion (cross-cut method), an initial coating adhesion test was performed. The adhesion of the coating film was evaluated on the basis of the following 0 to 5 based on the classification of the test results described in JIS K 5600-5-6.

<6-level evaluation>
0: The edges of the cut are completely smooth, and there is no peeling of any lattice.

  1 ... Small peeling of the coating film at the intersection of cuts. It is clearly not more than 5% that the crosscut is affected.

  2 ... The coating is peeled along the edge of the cut and / or at the intersection. The cross-cut part is clearly affected by more than 5% but not more than 15%.

  3 ... The coating film is partially or completely peeled along the edge of the cut, and / or various parts of the eye are partially or completely peeled off. The cross-cut portion is clearly affected by more than 15% but not more than 35%.

  4 ... The coating film is partially or completely peeled along the edge of the cut, and / or some eyes are partially or completely peeled off. The cross-cut portion is clearly affected by more than 35% but not more than 65%.

  5 ... When the degree of peeling exceeds Category 4.

<Adhesion after hot water resistance test>
JIS K 5600-6-2: According to liquid resistance (water immersion method), the test piece was immersed in warm water of 40 ± 1 ° C. for 240 hours. After completion of the prescribed test period, the test piece is taken out and placed at room temperature for 24 hours, and the adhesion of the coating film is evaluated based on the classification of the test result described in JIS K 5600-5-6 in the following 6 levels of 0-5. did.

<6-level evaluation>
0: The edges of the cut are completely smooth, and there is no peeling of any lattice.

  1 ... Small peeling of the coating film at the intersection of cuts. It is clearly not more than 5% that the crosscut is affected.

  2 ... The coating is peeled along the edge of the cut and / or at the intersection. The cross-cut part is clearly affected by more than 5% but not more than 15%.

  3 ... The coating film is partially or completely peeled along the edge of the cut, and / or various parts of the eye are partially or completely peeled off. The cross-cut portion is clearly affected by more than 15% but not more than 35%.

  4 ... The coating film is partially or completely peeled along the edge of the cut, and / or some eyes are partially or completely peeled off. The cross-cut portion is clearly affected by more than 35% but not more than 65%.

  5 ... When the degree of peeling exceeds Category 4.

[In Tables 1 and 2]
-UAC-1 (corresponding to component (A)): 1 mol of isophorone diisocyanate, Plaxel FM-3 (manufactured by Daicel Chemical Industries) [number average having one methacryloyl group and one primary hydroxyl group in a polycaprolactone oligomer Compound of molecular weight 472] Reaction product (hydroxyl group-containing urethane oligomer) with 1.8 mol (two methacryloyl groups in the molecule).

EAC-1 (corresponding to component (A)): oligomer of epoxy compound (“Epicoat 828” (manufactured by Yuka Shell Epoxy)) and methacrylic acid (two methacryloyl groups in the molecule)
・ Styrene (corresponding to (B) component)
-Trimethylolpropane triacrylate (corresponding to component (B)): There are three acryloyl groups in the molecule.

  Dipentaerythritol hexaacrylate (corresponding to component (B)): 6 acryloyl groups in the molecule.

・ Industrial nitrified cotton HIG1 / 2 seconds (corresponding to the component (C)): Nitrocellulose (Asahi Kasei Kogyo Co., Ltd.)
CAB321-0.1 (corresponding to component (C)): cellulose acetate butyrate, number average molecular weight 12,000 (manufactured by Eastman Kodak Company)
CAB551-0.01 (corresponding to component (C)): cellulose acetate butyrate, number average molecular weight 16,000 (manufactured by Eastman Kodak Company)
CAP-504-0.2 (corresponding to component (C)): cellulose acetate propionate, number average molecular weight 15,000 (manufactured by Eastman Kodak Company)
-Viro Ecole BE-400 (corresponding to component (C)): Amorphous polylactic acid resin (manufactured by Toyobo Co., Ltd.)
・ T-Butylperoxybenzoate (corresponding to component (D))
T-Butylperoxy 2-ethylhexanoate (corresponding to component (D))
・ Zinc stearate (internal release agent)
・ Titanium dioxide (color pigment)
・ Phthalocyanine blue (coloring pigment)
・ Carbon black (color pigment)
・ Talc (external pigment)

[ Reference Examples 12-14, 16-21, Examples 15, 22 and Comparative Examples 6-10]
A mold having a cavity for obtaining a resin molded product having a boss with a length of 300 mm, a width of 200 mm, a height of 30 mm, and a plate thickness of 2 mm and a boss having an outer diameter of 7 mm, an inner diameter of 4 mm, and a height of 10 mm is used. In-mold coating was performed on the molded article according to the embodiment shown in FIG. The mold temperature is set to 95 ° C, the barrel temperature is heated to 200 ° C, ABS resin is first heated and dissolved in the injection cylinder, and it takes about 1 second in the mold that is clamped with a clamping pressure of 350 tons. Injected and cooled for 30 seconds, the surface of the obtained molded article was solidified to such an extent that it could withstand the injection and flow pressure of the in-mold coating composition. Next, after the movable mold was separated by about 1 mm, each coating composition 6 cm ³ described in Tables 5 and 6 was injected between the mold surface and the surface of the molded article over about 0.5 seconds. After completion of injection, the mold clamping pressure was increased to 20 tons over 1 second and held for 60 seconds to cure the in-mold coating composition. The appearance of the obtained molded product, the presence or absence of coating film wrinkles on the boss, and the adhesion of the in-mold coating composition were evaluated in the same manner as in Reference Example 1. The results are shown in Tables 7 and 8.

[In Tables 5 and 6]
NK oligo U-4H (corresponding to component (A)): Urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.), 4 acryloyl groups in the molecule.

  -NK oligo U-6H (corresponding to component (A)): Urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.), 6 acryloyl groups in the molecule.

  -1,6 hexanediol diacrylate (corresponding to component (B)): There are two acryloyl groups in the molecule.

・ Bis (4-t-butylcyclohexyl) peroxydicarbonate (corresponding to component (D))
・ ZELEC-NE (internal release agent)

Sectional drawing which shows the structure of one compression molding apparatus suitable for forming a coating molding using the in-mold coating composition of this invention. Sectional drawing which shows the structure of another one injection molding apparatus suitable for forming a coating molding using the in-mold coating composition of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Split type upper mold 2 Split type lower mold 3 Movable plate of mold clamping device 4 Fixed plate of mold clamping device 5 Clamping cylinder 6 Split die 7 Injector 7A Shut-off pin 8 Measuring cylinder 8A Plunger regulator 9 Supply pump DESCRIPTION OF SYMBOLS 10 Storage part 11 Clamping board 12 of mold clamping apparatus Movable board 13 of mold clamping apparatus Fixed mold part 14 Movable mold part 15 Clamping cylinder 16 Cavity 17 Injection cylinder 18 Nozzle 19 Sprue 20 Rib 21 Ejector pin 22 at the time of mold release Injector 22A Shut-off pin 23 Metering cylinder 23A Plunger regulator 24 Storage unit 25 Supply pump

Claims (6)

(A) an oligomer having at least two (meth) acrylate groups, or an unsaturated polyester resin, (B) an ethylenically unsaturated monomer copolymerizable with the component (A), (C) a polylactic acid resin compound, (D) An organic peroxide initiator is an essential component, and (A) / (B) = 70/30 to 30/70 (parts by mass), and (A) + (B) with respect to 100 parts by mass, In-mold coating composition, wherein component C) is 20 to 100 parts by mass and component (D) is 0.2 to 5 parts by mass.
  The in-mold coating composition according to claim 1, wherein the polylactic acid resin compound as the component (C) is an amorphous polylactic acid resin compound. The in-mold coating composition according to claim 1 or 2 , wherein at least one of the components (A) and (B) has three (meth) acrylate groups. The in-mold coating composition according to claim 1 or 2 , wherein at least one of the components (A) and (B) has 4 to 8 (meth) acrylate groups. The in-mold coating composition according to any one of claims 1 to 4, further comprising a pigment.   A thermosetting resin molded article or a thermoplastic resin molded article, which is coated with the in-mold coating composition according to any one of claims 1 to 5.

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