JP4420841B2 - In-mold coating composition and method for producing in-mold coated molded article - Google Patents

Description

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

  In recent years, thermoplastic resin molded products used in automobiles, light electrical appliances, or building materials are often painted with paints containing aluminum pigments, pearls, mica, etc. when design is required. However, for this painting, it is necessary to prepare a separate painting facility, and because of the man-hours for painting and the increase in facilities for reducing volatile organic solvents generated by painting, The resin molded product is very expensive. Under such circumstances, there is an attempt to color the thermoplastic resin molded product with aluminum pigment in advance and omit the painting process, but the appearance is poor due to the orientation of the aluminum pigment flowing in the mold and the occurrence of weld lines. , The impact strength of the thermoplastic resin molded product is significantly reduced, the surface hardness is low, the surface is easily scratched, the weather resistance is inferior, the surface gloss is reduced by light, There was a drawback that the value decreased.

In order to solve such a drawback, a colored thermoplastic resin molding material is molded by an injection molding method, and (A) an oligomer having at least two (meth) acrylate groups in the same mold, or Contains at least one unsaturated polyester resin, (B) an ethylenically unsaturated monomer, (C) a scaly pigment having an average particle diameter of 5 to 150 μm, an aspect ratio of 1.5 to 100, and (D) a polymerization initiator. In a method for producing a thermoplastic resin molded article produced by injecting a coating agent, a method for producing a thermoplastic resin molded article having a concealment ratio of 0.6 or less when the coating amount is 1 ml / 100 cm ² (for example, patent document) 1) is known.
However, the method of Patent Document 1 has the drawback that the aluminum pigment flows in the mold and the generation of weld lines cannot be sufficiently prevented.

Japanese Patent Laid-Open No. 11-240042

  The present invention has been made on the basis of the above circumstances, and is used for in-mold coating molding in which the surface of a resin molded product is coated with a coating agent in the molding die during molding such as resin injection molding and injection compression molding. The present invention relates to a composition and a method for producing an in-mold coated molded article.

  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 fiber-based resin,
(D) a scaly pigment having an average particle diameter of 1 to 200 μm and an aspect ratio of 1 to 100, and (E) a polymerization initiator,
As an essential component, (A) / (B) = 80/20 to 20/80 (parts by mass), and (A) + (B) 100 parts by mass with respect to (C) component 1 to 20 The composition for in-mold coating molding, wherein the component is 0.1 to 20 parts by mass of the component (D) and 0.1 to 10 parts by mass of the component (E).
2. (1) A resin molded product is formed by injection molding, injection compression, injection press, reaction injection molding or compression molding in a cavity formed by a mold that is separable into at least two and relatively accessible. Process,
(2) After the molded product is cured or solidified to the extent that it can withstand the injection pressure and flow pressure of the in-mold coating molding composition described in 1 above, the molded product and the inner wall of the mold are contained in the same mold. And injecting and curing the in-mold coating molding composition,
(3) A step of removing the coated molded product from the mold,
A method for producing an in-mold coated product, comprising:

  According to the present invention, in a coating film having a so-called metallic feeling using a scaly pigment, it is possible to provide a coating composition which is excellent in the orientation of scaly pigments and does not cause weld lines. By using the inner coating composition, an easy and practical method for producing a 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). As essential components, a polymerizable unsaturated monomer, (C) a fiber-based resin, (D) a scaly pigment having an average particle diameter of 1 to 200 μm and an aspect ratio of 1 to 100, and (E) a polymerization initiator Contains optional components such as release agents, pigments such as color pigments and conductive pigments, modified resins, antioxidants, ultraviolet absorbers, curing accelerators, various dispersants, antifoaming agents, etc. Is included.

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

(1-1) Oligomer having at least two (meth) acrylate groups As the oligomer having at least two (meth) acrylate groups, for example, urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) Examples include acrylates, polyether (meth) acrylates, and oligomers of silicon (meth) acrylate.
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) ) Hydroxyalkyl (meth) acrylate is mixed with an abundance ratio such that the NCO / OH ratio is, for example, 0.8 to 1.0, preferably 0.9 to 1.0. Can be manufactured. 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 most of the free isocyanate groups are 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-pentanediol. 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,4-cyclohexanediol, 1,4-dimethylolcyclohexane, 4,8-dihydroxytri Cyclo [5.2.1.02,6] decane, 2,2-bis (4-hydroxycyclohexyl) propane, and the like can be given as representative examples.

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 an all compound when organic include, for example, an esterification reaction product obtained by reacting a saturated or unsaturated dicarboxylic acid and / or acid anhydride thereof with an excess of alkyl diol, and alkyl diol. 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 thereof 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 an 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 is produced, for example, by a reaction between a polyester polyol having a hydroxyl group at the terminal and an unsaturated carboxylic acid. be able to. 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 comprises, for example, an epoxy compound and an unsaturated carboxylic acid as described above as an epoxy group 1. It is produced by a ring-opening addition reaction of an acid to a normal epoxy group, using a carboxyl group equivalent per equivalent, for example, at a ratio of 0.5 to 1.5. 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, for example, an esterification reaction between a hydroxyl group of an alcoholic siloxane compound and (meth) acrylic acid. It was manufactured by. 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, If necessary, it can be produced by reacting a saturated polycarboxylic acid. 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) Component (B) 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, triallyl isocyanurate mentioned as representative.

Preferably, it has an aliphatic (meth) acrylate monomer such as tripropylene glycol diacrylate (TPGDA) and 1,6-hexanediol diacrylate (1,6HDDA), and an alicyclic structure such as cyclohexyl methacrylate ( It is a (meth) acrylate monomer.
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) = 20. : 80-80: 20, preferably 33: 67-77: 23 is suitable. If it is this range, the coating composition which has a moderate hardening characteristic and viscosity will be obtained.
In particular, the component (B) is suitably used in an amount of 25 to 400 parts by mass, preferably 30 to 200 parts by mass with respect to 100 parts by mass of the component (A). If the amount of the component (B) is 25 parts by mass or more, it is preferable because a uniform coating can be obtained without the viscosity of the coating composition becoming too high or the fluidity in the mold being inferior. On the other hand, if the amount of component (B) is 400 parts by mass or less, the viscosity of the coating composition will not be too low, and bubbles will not be taken into the coating composition when flowing in the mold, and it will be robust. This is preferable because a cured film can be obtained.

(3) Component (C) The component (C) used in the present invention uses a cellulose resin such as nitrocellulose, acetyl cellulose, cellulose acetate butyrate, cellulose propionate, ethyl cellulose, or other fibrous resin. be able to.
(C) The compounding quantity of a component is 1-20 mass parts with respect to a total of 100 mass parts of the said (A) and (B) component, Preferably it is 2-10 mass parts. When the blending amount of the fiber-based resin is 1 part by mass or more, a coating film having a metallic feel without aggregation of scaly pigments at the fluid end of the coating composition can be obtained. On the other hand, if the blending amount of the fiber-based resin is 20 parts by mass or less, the movement of the scaly pigment in the coating molding composition can be stopped in the mold, and the orientation of the scaly pigment is excellent. A coating composition free of weld lines is obtained.

(4) (D) Component The scaly pigment of the (D) component used in the present invention has an average particle diameter of 1 to 200 μm and an aspect ratio of 1 to 100. Specifically, aluminum, nickel, graphite, Typical examples include mica surface-treated with titanium oxide and the like, and glass flakes surface-treated with brass and silver. The scaly pigment may completely hide the color of the thermoplastic resin molded product, or does not completely hide the color of the thermoplastic resin molded product, that is, the color of the thermoplastic resin molded product. It has a specific particle size and aspect ratio in order to create a metallic appearance due to the glitter of the scaly pigment in the coating while preventing weld lines due to the surface orientation of the scaly pigment. is necessary. Therefore, the scaly pigment has an average particle diameter of 1 to 200 μm, preferably 15 to 80 μm, and an aspect ratio of 1 to 100, preferably 2 to 85.

  When the average particle size is larger than 200 μm, scaly pigments cue from the surface of the coating film, which is liable to cause poor appearance and discoloration due to acid / alkali. On the other hand, when the particle diameter is smaller than 1 μm, the metallic feeling tends to be insufficient. On the other hand, when the aspect ratio exceeds 100, the orientation of the pigment becomes remarkable and the weld line tends to become prominent, which is not preferable in terms of appearance. On the other hand, when the aspect ratio is less than 1, it is not preferable because a feeling of brightness is easily lost and a metallic feeling is insufficient.

The amount of the scaly pigment is 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, with respect to 100 parts by mass in total of the components (A) and (B). is there. When the amount of the scaly pigment exceeds 20 parts by mass, the scaly pigment begins to cue from the surface of the coating film, and it is not preferred because it tends to cause poor appearance and discoloration due to acid / alkali. On the other hand, if the amount of the scaly pigment is less than 0.1, the luminance feeling tends to be lost and the metallic feeling is insufficient, which is not preferable.
Moreover, the scale-like pigment may be resin-coated as another aspect of the present invention.

(5) (E) component (E) component used by this invention generate | occur | produces a free radical, and is used in order to superpose | polymerize the said (A) component and (B) component. Examples of the polymerization initiator include tertiary butyl peroxybenzoate, tertiary butyl peroxy 2-ethylhexanoate, tertiary butyl peroxyisopropyl carbonate, lauroyl peroxide, tertiary butyl oxylaurate, 1,1- A typical example is bis (tertiary butyl peroxy) -3,3,5-trimethylcyclohexane.
The blending amount of the polymerization initiator is 0.1 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.

(6) Release agent In this invention, in order to release a cured coating film smoothly from a metal mold | die, a release agent can be used together arbitrarily. For example, a release agent having a melting point of 125 ° C. or lower, preferably 122 ° C. or lower, more preferably having a liquid at room temperature is suitable. For example, if it is 125 degrees C or less, even if the desired mold release effect is about 40-110 degreeC, the reaction heat accompanying hardening of dicyclopentadiene and urethane exists, and high temperature melting of 200-240 degreeC Considering that the ABS resin is cooled and solidified in the mold, the surface temperature of the molded product when the coating composition is injected is considered to be sufficiently higher than the melting point of the mold release agent of 125 ° C. is there. Examples of such 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. Examples thereof include alcohol dibasic acid esters. The compounding quantity of a mold release agent is 0.1-10 mass parts with respect to a total of 100 mass parts of the said (A) component, (B) component, and (E) component, Preferably, it is 0.2-3. It is suitable that it is a mass part. Within this range, the mold release effect is suitably exhibited.

(7) Pigment The in-mold coating molding composition of the present invention further includes various color pigments, extender pigments, conductive pigments, etc. that have been conventionally used for other plastics and paints as needed. Can be used in combination. Color pigments include, for example, white 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 product, gives it an aesthetic appearance, disperses the shrinkage stress associated with the film effect, improves adhesion to the molded product, smoothes the surface irregularities, and improves the appearance of the molded product surface. Or added for the purpose of preventing charging by imparting conductivity to the cured coating film. In the case of a clear metallic finish, it is not always necessary to add a color pigment.

(8) Others In the in-mold coating molding composition of the present invention, if necessary, polymethyl methacrylate resin, saturated polyester resin, vinyl acetate resin, resin particles having a particle size of 0.1 to 30 μm, etc. Various additives such as a modified resin, an antioxidant, an ultraviolet absorber, a curing accelerator, a pigment dispersant, and an antifoaming agent may be blended.
The in-mold coating molding composition of the present invention contains substantially no solvent. If the solvent is not substantially contained, solvent vapor is not taken into the mold coating composition during flow in the mold, and pinholes are not generated. It is because it is preferable. 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.

(9) Resin Molded Article As the synthetic resin molded article to which the in-mold coating molding composition of the present invention is applied, conventionally known various thermosetting molding materials and various thermoplastic synthetic resin materials can be used. . As thermosetting molding materials, for example, SMC using unsaturated polyester resin, epoxy acrylate resin, phenol resin as matrix, fiber reinforced plastic molding material called BMC, RTM molding using unsaturated polyester resin, epoxy acrylate resin as matrix Examples thereof include RIM molding materials using materials, 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. Resin, ASA resin, ABS resin, AES resin, ASA resin, or various alloy materials of these resins can be used.
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.

(10) Manufacturing method of in-mold coated molded product Hereinafter, a configuration of a molding machine, a molding die and a coating composition injection device for carrying out the manufacturing method of an in-mold coated molded product of the present invention will be described with reference to the drawings. Although specifically described, the scope of the present invention is not limited by such a specific molding machine.
In FIG. 1, reference numeral 1 is a fixed plate of a mold clamping device of an injection molding machine, and 2 is a movable plate, each having a fixed mold part 3 and a movable mold part 4 which are molding members facing each other. The movable platen 2 is configured to be moved back and forth by the mold clamping cylinder 5. Then, a cavity 6 having a required shape is formed at a fitting portion between the fixed mold part 3 and the movable mold part 4, and a molten or soft synthetic resin molding material is injected, filled, and cured therein. Or it solidifies. When the molten synthetic resin molding material is injected and filled, the synthetic resin molding material can be injected into the cavity 6 from the injection cylinder 7 having a screw through the nozzle 8 and the sprue 9. In the figure, reference numeral 10 denotes a rib part (boss part), and 11 denotes an ejector pin at the time of mold release. In the in-mold coating molding method of the present invention, a toggle type injection molding machine is suitably used for injection molding, injection compression molding, and injection press molding. (Not shown)

In addition, a shear edge structure portion is formed at a fitting portion of the fixed mold 3 and the movable mold 4, and a fitting groove (not shown) is provided in the shear edge structure portion, and a heater is fitted therein. This improves the sealing performance of the shear edge structure portion with respect to the coating agent.
On the other hand, in FIG. 1, as the coating agent injection means, an injector 12 having a shut-off pin 12A, a coating metering cylinder 13 for supplying a predetermined amount of coating material to the injector 12, and a coating agent from its storage section 14 are used. A supply pump 15 for supplying the measuring cylinder 13 is provided. The metering cylinder 13 is provided with a plunger regulator 13A for injecting a coating material.
Thus, when molding, first, the mold clamping cylinder 5 is operated to close the molds (the fixed mold part 3 and the movable mold part 4) and apply the mold clamping pressure. This mold clamping pressure must be able to counter the injection pressure of the synthetic resin molding material. Usually, this injection pressure is a high pressure of 39 to 245 MPa (400 to 2,500 kgf / cm ² ) at the nozzle 8 portion. In this process, the supply pump 15 is operated to supply a necessary amount of coating material to the metering cylinder 13.

Next, a molten or softened synthetic resin molding material is injected from the injection cylinder 7 into the cavity 6 via the nozzle 8. When the synthetic resin molding material is properly cured or solidified in the mold (to the extent that it can withstand the coating injection pressure and flow pressure), the mold clamping pressure is reduced or the fixed mold part 3 and the movable mold part. 4 is opened to such an extent that the fitting part does not leave. Next, the injector 12 operates its shut-off pin 12A to open its injection port. Next, the plunger regulator 13A for injecting the coating material of the measuring cylinder 13 is operated to inject and fill the coating material between the cavity 6, that is, between the inner wall of the fixed mold part 3 and the surface of the synthetic resin molded product.
After the coating agent is injected, the injection port is closed again with the shut-off pin 12A, the mold clamping cylinder 5 is operated to perform the clamping operation, and the coating agent is diffused in the mold to achieve coating on the surface of the molded product.

In FIG. 2, the method of implementing the reaction injection molding method (RIM) using the molding material which has dicyclopentadiene as a main component as a thermosetting molding material is shown. The upper mold 21 and the lower mold 22 are molding mold members that face each other. The upper mold 21 and the lower mold 22 are fixed to a movable platen (not shown) and a fixed platen (not shown) of the mold clamping device, respectively, and the movable plate is moved forward and backward by a mold clamping cylinder (not shown). It is configured to be. A cavity 23 having a required shape is formed by both mold members 21 and 22, and a molding material containing dicyclopentadiene as a main component is filled therein and cured. A molding material mainly composed of dicyclopentadiene is filled in the cavity 23 by an apparatus located on the left side in the drawing. Specifically, after the temperature of the molding material is adjusted in the storage tanks 24 and 25, the pressure is increased to 5 to 50 MPa (50 to 500 kgf / cm ² ) by the operation of the hydraulic cylinders 30 and 31 by the measuring cylinders 26 and 27. Then, they are mixed by being ejected from the opposed nozzles in the mixing head 33 and colliding with each other.

In the embodiment shown in FIG. 2, the coating composition is injected by a device on the right side of the drawing, which device comprises a mixing head 35 with a piston 34 with shutoff and injection functions, and a predetermined amount in the mixing head 35. Metering cylinders 36 and 37 for supplying the coating composition and hydraulic cylinders 30 and 31 for pressurizing the coating composition are provided on these metering cylinders. In the mixing head 35, the coating composition is ejected from the opposed nozzles and mixed by colliding with each other. Other methods for mixing the coating composition include, for example, a method using a static mixer, a method using a dynamic mixer, and an atomizing method, but are not limited thereto.
In the case of molding using the mold shown in FIG. 2, first, a mold clamping cylinder (not shown) is operated to close the upper mold 21 and the lower mold 22 and apply mold clamping pressure. This clamping pressure is usually 0.3 to 1 MPa (3 to 10 kgf / cm ² ). Next, a molding material (monomer) containing dicyclopentadiene as a main raw material is injected from the mixing head 33 into the cavity 33 and reacted in the mold to form a thermosetting resin molding. At the stage where the molding material is cured to the extent that it can withstand the injection pressure and flow pressure of the coating composition in the mold, the mold clamping pressure is left as it is, or the pressure is reduced or released.

The mixed coating composition is then injected immediately before injection. When injecting the coating composition, the liquid composed mainly of the resin main component, which is the raw material of the coating composition, and the liquid composed of the curing agent that cures the main component are heated in the raw material storage tanks 23 and 24 of the coating composition, respectively. After the adjustment, the pressure is increased by the measuring cylinders 36 and 37 by the action of the hydraulic cylinders 40 and 41, and the liquid is ejected from the opposed nozzles in the mixing head 35, collides with each other, and is mixed. A coating composition is injected into the mixing head portion between the inner wall of the upper mold 21 and the surface of the synthetic resin molding material by a piston 34 that also serves as a shut-off pin.
In this way, by mixing the raw material agent of the coating composition to be reacted immediately before injection to form a coating composition, thickening and gelation occur compared to using a coating composition prepared by mixing in advance. Therefore, fluidity during injection is good, and clogging of the injection device can be prevented.
After the injection of the raw material of the coating composition is completed, if necessary, the mold clamping cylinder is operated to perform a mold clamping operation, and the coating composition is cured in the mold. Next, the mold clamping cylinder is operated, the molds 1 and 2 are separated, and the coated molded product 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.

Example 1 and Comparative Example 1
A mold having a cavity for obtaining a synthetic resin molded product having a side cover shape having a length of 300 mm, a width of 170 mm, and a height of 40 mm was subjected to in-mold coating on the molded product according to the embodiment of FIG. In this case, the mold temperature is set to 95 ° C. and heated to a barrel temperature of 200 ° C. First, the ABS resin is heated and dissolved in the injection cylinder, and the mold is clamped at a mold clamping pressure of 300 tons. Injection was performed for 1 second, and cooling was performed for 40 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 coating composition. Next, after the movable mold was separated by about 1 mm, each coating composition 6 cm ³ described in Table 1 was injected between the mold surface and the surface of the molded article over about 0.5 seconds. After completion of the injection, the clamping pressure was increased to 10 tons over 1 second and held for 5 seconds. The mold clamping pressure was then increased to 20 tons and held for 55 seconds to cure the coating composition. The composition of the coating composition is shown in Table 1 below. Further, the appearance of the obtained molded product and the adhesion of the coating composition are shown in Table 2 below.

note)
UAC-1 (corresponding to component (A))
Reaction reaction between 1 mol of isophorone diisocyanate and 1.8 mol of Plaxel FM-3 (manufactured by Daicel Chemical Industries, Ltd.) [a compound having a number average molecular weight of 472 having one methacryloyl group and one primary hydroxyl group in a polycaprolactone oligomer] (Hydroxyl group-containing urethane oligomer) (two methacryloyl groups in the molecule).
UAC-2 (corresponding to component (A))
Synthesized from 2 mol of bis (4-isocyanatocyclohexyl) methane, 1 mol of ethylene oxide adduct (number average molecular weight 1,000) of 2,2-bis (4-hydroxycyclohexyl) propane, and 2.1 mol of 2-hydroxyethyl methacrylate Urethane methacrylate oligomer (two methacryloyl groups in the molecule)
1,6HDDA (corresponding to (B) component)
6-hexanediol diacrylate
Industrial nitrified cotton HIG1 / 2 seconds (corresponding to component (C))
Nitrocellulose (Asahi Kasei Kogyo Co., Ltd.)
CAB551-0.2 (corresponding to the component (C))
Cellulose acetate butyrate (Eastman Kodak)

CAB381-2 (corresponding to component (C))
Cellulose acetate butyrate (Eastman Kodak)
CAB381-20 (corresponding to the component (C))
Cellulose acetate butyrate (Eastman Kodak)
Metashine MC5090RS (corresponding to (D) component)
Average particle size 90μm, aspect ratio 18 (Nippon Sheet Glass Co., Ltd.)
Metashine MC1080RS (corresponding to (D) component)
Average particle size 80μm, aspect ratio 80 (manufactured by Nippon Sheet Glass Co., Ltd.)
Metashine MC1080RB (corresponding to (D) component)
Average particle size 80μm, aspect ratio 80 (manufactured by Nippon Sheet Glass Co., Ltd.)
Bis (4-t-butylcyclohexyl) peroxydicarbonate (corresponding to component (E))
Cross-linking efficiency 24.0, 1 minute half-life temperature 92 ° C
ZELEC-UN (corresponding to (6) release agent)
Phosphate alcohol (DuPont)
TITUVIN123 (corresponding to (8) antioxidant)
(Ciba Specialty Chemical Co., Ltd.)
TITUVIN400 (corresponding to (8) UV absorber)
(Ciba Specialty Chemical Co., Ltd.)

Note 1) Appearance of coating film: The appearance of the obtained coated molded product was visually determined for the presence or absence of weld line of scaly pigments and the presence or absence of aggregation of scaly pigments at the flow end of the coating composition.
Note 2) According to JIS K 5400 8.5.2 grid cellophane tape method. However, the interval between the cuts is 1 mm, and the square is 100.
Evaluation criteria: Best 10 → Worst 0

Example 2 and Comparative Example 2
A mold having a cavity for obtaining a synthetic resin molded product having a side cover shape having a length of 300 mm, a width of 170 mm, and a height of 40 mm was subjected to in-mold coating on the molded product according to the embodiment of FIG. In this case, the mold temperature is set to 95 ° C. and heated to a barrel temperature of 200 ° C. First, the ABS resin is heated and dissolved in the injection cylinder, and the mold is clamped at a mold clamping pressure of 300 tons. Injection was performed for 1 second, and cooling was performed for 40 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 coating composition. Next, after moving the movable mold about 1 mm, 6 cm ^{3 of} each coating composition described in Table 3 was injected between the mold surface and the surface of the molded article over about 0.5 seconds. After completion of the injection, the clamping pressure was increased to 10 tons over 1 second and held for 5 seconds. The mold clamping pressure was then increased to 20 tons and held for 55 seconds to cure the coating composition. The composition of the coating composition is shown in Table 3 below. Table 4 below shows the appearance of the obtained molded product and the adhesion of the coating composition.

note)
TAYCA PEARL TP-690 (corresponding to component (D))
Titanium oxide coated mica, particle size 7-45 μm (manufactured by Teika) (average particle size 25 μm, aspect ratio 70)

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed platen of mold clamping device 2 Movable platen of mold clamping device 3 Fixed mold part 4 Movable mold part 5 Clamp cylinder 6, 23 Cavity 7 Injection cylinder 8 Nozzle 9 Sprue 21 Upper mold 22 Lower mold 24, 25 RIM molding Resin raw material tank 33, 35 Mixing head 43, 44 Coating composition raw material storage tank

Claims (3)

(A) a urethane (meth) acrylate oligomer having at least two (meth) acrylate groups,
(B) an ethylenically unsaturated monomer copolymerizable with the component (A), wherein the monomer is selected from an aliphatic (meth) acrylate monomer or a (meth) acrylate monomer having an alicyclic structure ;
(C) a fibrous resin selected from nitrocellulose, acetylcellulose, cellulose acetate butyrate, cellulose propionate, or ethylcellulose ;
(D) a scaly pigment having an average particle diameter of 1 to 200 μm and an aspect ratio of 1 to 100, and (E) a polymerization initiator,
As an essential component, (A) / (B) = 80/20 to 20/80 (parts by mass), and (A) + (B) 100 parts by mass with respect to (C) component 1 to 20 The composition for in-mold coating molding, wherein the component is 0.1 to 20 parts by mass of the component (D) and 0.1 to 10 parts by mass of the component (E). The composition for in-mold coating molding according to claim 1, wherein the scaly pigment of the component (D) is resin-coated. (1) A resin molded product is formed by injection molding, injection compression, injection press, reaction injection molding or compression molding in a cavity formed by a mold that is separable into at least two and relatively accessible. Process,
(2) After the molded product is cured or solidified to such an extent that it can withstand the injection pressure and flow pressure of the in-mold coating molding composition according to claim 1 or 2 , the molding is performed in the same mold. Injecting and curing the in-mold coating molding composition between the product and the inner wall of the mold,
(3) A step of removing the coated molded product from the mold,
A method for producing an in-mold coated product, comprising:

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