JPH05239164A - Thermosetting resin composition for in-mold coating molding and coated molding - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a thermosetting resin composition for in-mold coating molding, which makes it possible to obtain a coated molded article having a coating layer with good adhesion. [Structure] A thermosetting resin composition used for a substrate in an in-mold coating molding method, which comprises coating a thermosetting coating material on a substrate to form a coating layer. A compound having a heavy bond and an isocyanate group, and /
Alternatively, a thermosetting resin composition comprising a compound having a copolymerizable double bond and an isothiocyanate group in the molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin composition used in an in-mold coating molding method for molding a coating layer on a base material in a mold, and in particular, adhesion between the base material and the coating layer. The present invention relates to a thermosetting resin composition that makes it possible to obtain a coated molded article having excellent properties, and a coated molded article using the thermosetting resin composition.

[0002]

2. Description of the Related Art In recent years, a molded product made of a thermosetting molding material has been widely used for industrial parts and the like as a substitute member for metal parts and the like. As the thermosetting molding material, a sheet molding compound (hereinafter abbreviated as SMC) or a bulk molding compound (hereinafter abbreviated as BMC) is generally used. However, in the molded product obtained by molding SMC or BMC by heating / pressurizing in a mold, pores, microcracks,
Surface defects such as sink marks and undulations tended to occur. When such a surface defect is present, it is difficult to form a coating film having sufficient adhesion and surface properties even if the molded product is coated by a usual method.

Therefore, a so-called in-mold coating molding method has been proposed as a method for concealing the above-mentioned surface defects. For example, Japanese Patent Application Laid-Open No. 53-71167 discloses a method of forming a coating layer on a molded article by heating and pressurizing the SMC in the mold to semi-cure the SMC, then opening the mold and injecting a coating material. It is disclosed. On the other hand, JP-A-61-273
No. 921 discloses a method of forming a coating layer on the surface of a molded article by injecting a coating material at an injection pressure higher than the molding pressure and curing the same during compression molding.

[0004]

However, the in-mold coating molding method described in the above-mentioned prior art has a problem that the adhesiveness to the coating layer is not sufficient. An object of the present invention is to provide a thermosetting resin composition for in-mold coating molding, which enables to obtain a coated molded article having good coating layer adhesion in the above-mentioned in-mold coating molding method, and such a coating. It is to provide molded products.

[0005]

The invention according to claim 1 relates to an in-mold coating molding method in which a thermosetting coating material is coated on a base material to form a coating layer. A curable resin composition, a compound having a copolymerizable double bond and an isocyanate group in the molecule (hereinafter abbreviated as unsaturated isocyanate), and / or a copolymerizable double bond and an isothiocyanate group in the molecule It is characterized by containing a compound having the following (hereinafter abbreviated as unsaturated isocyanate).

The invention according to claim 2 is a substrate,
A coated molded article, comprising a coating layer formed on a substrate, wherein the substrate is formed by using the thermosetting resin composition according to the invention of claim 1. .. Hereinafter, the details of the invention described in claims 1 and 2 will be described.

Unsaturated Isocyanate The unsaturated isocyanate used in the invention described in claim 1 can be obtained by reacting an alkali metal isocyanic acid salt with an alkenyl halide by a known and conventional method. Specific examples of unsaturated isocyanates include allyl isocyanate, 1-butene 3 isocyanate, 2 methyl propene 3 isocyanate and the like. In addition,
The unsaturated isocyanate can also be synthesized by an addition reaction of an unsaturated alcohol and polyisocyanate.

Unsaturated Isothiocyanate The unsaturated isothiocyanate used in the invention of claim 1 is produced by reacting an alkali metal isothiocyanate with an alkenyl halide by a known and conventional method. .. Specific examples of unsaturated isothiocyanates include allyl isothiocyanate, 1-butene 3 isothiocyanate, 2 methylpropene 3 isothiocyanate and the like. The unsaturated isothiocyanate can also be synthesized by addition reaction of unsaturated alcohol and polyisothiocyanate.

Unsaturated isocyanate and unsaturated isothio
Amount of cyanate blended In the invention according to claim 1, the unsaturated isocyanate and / or unsaturated isothiocyanate as described above is blended in the thermosetting resin composition for constituting the substrate,
This blending ratio is preferably 0.1 to 70% by weight based on the total resin content of the thermosetting resin composition (the total amount of the thermosetting resin, the copolymerizable monomer and the thermoplastic resin described below). Is. If it is less than 0.1% by weight, it is difficult to obtain the effect of improving the adhesiveness with the coating layer. On the contrary, if it is compounded in an amount of more than 70% by weight, the viscosity of the thermosetting resin composition becomes too low, This is because it becomes difficult to form SMC or BMC (that is, solid).

The thermosetting resin used in the thermosetting resin composition for constituting the thermosetting resin substrate is a three-dimensional network by cleavage addition reaction of a double bond using a thermally decomposable radical catalyst. An unsaturated polyester resin having a reactive double bond in the molecule, which can form a structure, a vinyl ester (epoxy acrylate) resin, a urethane acrylate resin, or the like can be used. These resins may be used alone or in combination of two or more.

The above-mentioned unsaturated polyester resin is usually produced by a known and commonly used method, usually an organic polyol, an aliphatic unsaturated polycarboxylic acid and, if necessary, an aliphatic saturated polycarboxylic acid and / or an aromatic polycarboxylic acid. Manufactured from. On the other hand, the vinyl ester resin is also generally produced by a known and commonly used method from an epoxy resin and a monocarboxylic acid having a reactive double bond such as (meth) acrylic acid.

Further, the urethane acrylate resin is
Usually, it is produced by reacting an organic polyol such as an alkylene diol, an alkylene diol ester, an alkylene diol ether, a polyether polyol or a polyester polyol with an organic polyisocyanate and further reacting with a hydroxyalkyl (meth) acrylate.

Examples of the organic polyol used for the unsaturated polyester resin include diols, triols, tetrols and mixtures thereof, and they are mainly classified into aliphatic polyols and aromatic polyols. Typical examples of the aliphatic polyol include ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, triethylene glycol, neopentyl glycol, dibromoneopentyl glycol, hexamethylene glycol, trimethylene glycol, trimethylolpropane, There are glycerin, pentaerythritol diallyl ether, hydrogenated bisphenol A, and the typical aromatic polyols are bisphenol A or bisphenol S or bisphenol A or bisphenol S of ethylene oxide, propylene oxide or butylene oxide. Polyoxyalkylene obtained by adding such an aliphatic oxirane compound in an average of 1 to 20 in one molecule There is scan phenol A or polyoxyalkylene bisphenol S and the like.

The aliphatic unsaturated carboxylic acid is (anhydrous) maleic acid, fumaric acid, (anhydrous) itaconic acid or the like, and the aliphatic saturated carboxylic acid is sebacic acid, adipic acid, (anhydrous) succinic acid or the like. However, as the aromatic carboxylic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride and the like are used.

The epoxy resin used for the vinyl ester resin is also a bisphenol A type epoxy resin produced from epichlorohydrin and bisphenol A, a bromine produced from epichlorohydrin and brominated bisphenol A, also by a known method. Bisphenol A type epoxy resin, novolac type epoxy resin produced by glycidyl etherification of phenol novolac or orthocresol novolak, obtained by reacting various amines with epichlorohydrin,
Tetraglycidyl metaxylene diamine, tetraglycidyl 1,3-bisaminomethylcyclohexane, tetraglycidyl aminodiphenylmethane, triglycidyl-
Glycidyl amine compounds such as p-aminophenol, triglycidyl-m-aminophenol, diglycidyl aniline and diglycidyl orthotoluidine are used.

Examples of the polyol used in the urethane acrylate resin include alkylene diols such as ethylene glycol, propylene glycol, diethylene glycol, diisopropylene glycol, polyethylene glycol, polypropylene glycol, butane diol, and other hydroxyalkyl ethers. Polyoxymethylene, polyethylene oxide, polypropylene oxide and the like are used as the polyether polyol, and polyester polyols having hydroxyl groups at both ends which are produced from the above-mentioned organic polyol and polycarboxylic acid are used as the polyester polyol.

As the polyisocyanate used for the urethane acrylate resin, tolylene diisocyanate, isophorone diisocyanate, polymethylene polyphenyl diisocyanate and the like are used.

The hydroxyalkyl (meth) acrylate used in the urethane acrylate resin is usually hydroxyethyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. are used, and the hydroxyl group is usually bonded to the carbon at the beta position of the alkyl group. Alkyl groups can usually contain up to 8 carbon atoms.

The thermosetting resin composition of the present invention also contains
Copolymerizable monomers such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, diallylphthalate, various acrylate monomers, various methacrylate monomers and low-shrinking agents, polyvinyl acetate, polymethyl (meth) acrylate, polyethylene, ethylene Thermoplastic resins such as vinyl acetate copolymers, vinyl acetate-styrene copolymers, polybutadiene, saturated polyesters, saturated polyethers and the like can be used in appropriate amounts as needed.

Further, the thermosetting resin composition of the present invention may contain an appropriate amount of inorganic filler depending on the purpose and application. Examples of usable inorganic fillers are as follows. Ie sulfur, graphite,
Elemental minerals such as diamond, sulfide minerals such as pyrite, halogenated minerals such as rock salt and potassium rock salt, carbonate minerals such as calcium carbonate, phosphate minerals such as cyanite, vanadate minerals such as carnotite, and heavy crystals Sulfate minerals such as stone (barium sulfate), gypsum (calcium sulfate), borate minerals such as borax, titanate minerals such as perovskite, mica, talc (talc), pyrophyllite, kaolin, quartz, Natural or artificial minerals centered on silicate minerals such as feldspar, titanium oxide, steel balls (aluminum oxide), metal (hydr) oxides such as aluminum hydroxide, and glass products such as (hollow) glass spheres. What was processed, refined | purified or processed, and those mixtures are used. Further, the filler is preferably added in a ratio of 0 to 300 parts by weight with respect to 100 parts by weight of the thermosetting resin. When the amount added exceeds 300 parts by weight, it becomes difficult to uniformly disperse the filler in the resin and the monomer, and the viscosity becomes too high, so the fluidity in the mold decreases and the dimensional stability Is reduced.

Further, in the thermosetting resin composition of the present invention,
As a reinforcing material, various reinforcing fibers, that is, glass fibers, carbon fibers, and the like can be added in appropriate amounts as needed. Furthermore, in the thermosetting resin composition of the present invention, if necessary, ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, alkyl peresters, percarbonates, and peroxy compounds. Known polymerization initiators such as ketals, known curing accelerators such as dimethylaniline and cobalt naphthenate, polymerization inhibitors such as parabenzoquinone, carbon black, titanium oxide, iron oxide, cyanine pigments, aluminum flakes, nickel powder. , Pigments such as gold powder and silver powder, azo dyes and anthraquinone dyes, indigoid dyes, stilbene dyes, conductivity imparting agents such as carbon black, emulsifiers, metal soaps such as zinc stearate, aliphatic phosphates, lecithin A releasing agent or the like can be added in an appropriate amount according to the use and purpose.

Thermosetting Coating Material The thermosetting resin composition according to the invention of claim 1 is
It is used in combination with a thermosetting coating material that has been conventionally used in the in-mold coating molding method. In this case, as the thermosetting coating material, an unsaturated polyester resin, a vinyl ester resin and / or a urethane acrylate resin as a thermosetting resin mixed with various fillers and additives as required. Used.

Molding method The thermosetting resin composition of the invention according to claim 1 is made into a thermosetting molding material in the form of SMC or BMC by a conventionally known method, and together with the thermosetting coating material, a mold Used in the inner coating molding method. The steps other than the use of the specific thermosetting molding material may be carried out according to a conventionally known in-mold coating molding method. For example, 130-1
Put SMC in the molding die heated to 60 ° C
After pressure 30 seconds to 5 minutes pressed at a 120 kg / cm ^2, the mold slightly open injected mold coating composition, then 5~120kg / cm ^2, 30 at 130 to 160 ° C. By reheating and repressurizing for 2 seconds to 5 minutes, the in-mold coating composition can be spread over the entire surface of the molded SMC and cured to form a coating layer.

Further, as disclosed in Japanese Patent Laid-Open No. 61-273921, SMC at 130 to 160 ° C., 40 to 1
Mold coating composition at a high pressure of 100 to 300 / cm ² using a high pressure injection machine in a state where the pressure was reduced to 10 to 30 kg / cm ² after several tens of seconds to several minutes pressed at 20 kg / cm ² Is injected into the mold and again 30 to 100 kg / cm
There is also a method of increasing the pressure to ² to spread-cure the composition for in-mold coating. When the thermosetting resin composition of the present invention is used in the in-mold coating method as described above, the coated molded article according to claim 2 can be easily obtained.

[0025]

In the thermosetting resin composition according to the invention of claim 1, since the unsaturated isocyanate and / or unsaturated isothiocyanate is contained, the unsaturated isocyanate and / or unsaturated isothiocyanate The polymerizable double bond undergoes a copolymerization reaction with a thermosetting resin at the time of pressure molding to expose an isocyanate group or an isothiocyanate group on the surface of the thermosetting molding material constituting the substrate. The exposed isocyanate group or isothiocyanate group has a function of reacting with active hydrogen such as OH group and NHCO group in the thermosetting resin composition constituting the thermosetting coating material to form a chemical bond. Therefore, the adhesiveness between the coating layer and the substrate is enhanced by the chemical bond.

[0026]

According to the invention described in claim 1, since the unsaturated isocyanate and / or unsaturated isothiocyanate is contained in the thermosetting resin composition for constituting the substrate, When used in the coating molding method, an isocyanate group or an isothiocyanate group is exposed on the surface of the base material and reacts with active hydrogen such as OH group or NHCO group in the thermosetting coating material to form a chemical bond. Therefore, it is possible to obtain the coated molded article according to claim 2 having excellent adhesion between the coating layer and the substrate.

[0027]

EXAMPLES Examples of the present invention will be described below. In the following, "parts" means parts by weight unless otherwise specified.

Preparation of Resin Liquid In the following examples, the unsaturated polyester resin liquid obtained by the following steps was used. That is, 5 mol of isophthalic acid, 5 mol of maleic acid and 10 mol of polypropylene glycol were condensed according to a conventionally known method to obtain an unsaturated polyester resin having a molecular weight of about 1,000. The unsaturated polyester resin obtained was dissolved in a styrene monomer to obtain an unsaturated polyester resin liquid. The styrene content in this unsaturated polyester resin liquid was 40% by weight.

Example 1 As the thermosetting resin composition for forming the base material, the following composition was prepared. Unsaturated polyester resin liquid: 70 parts Polystyrene low-contracting agent (containing about 30% by weight of polystyrene resin and about 70% by weight of styrene): 30 parts Allyl isocyanate (manufactured by Wako Pure Chemical Industries, Ltd.): 5 parts

Calcium carbonate powder (manufactured by Nitto Koka Co., Ltd., trade name: NS-100) ... 120 parts Hardener (t-butylperoxybenzoate) ... 1 part Thickener (magnesium oxide powder, manufactured by Kyowa Chemical Industry Co., Ltd., Product name: Kyowamu 150) ... 1 copy

After thoroughly mixing the above compositions and stirring, S
60 parts of glass fiber (ER4630LBD166W manufactured by Asahi Fiber Glass Co., Ltd., cut into a length of 25 mm) was impregnated with an MC impregnation device to obtain SMC as a thermosetting resin composition. On the other hand, 100 parts of the unsaturated polyester resin liquid, calcium carbonate powder (NS-100) 10
0 part and curing agent (t-butyl peroxybenzoate)
A thermosetting coating material was obtained by thoroughly mixing 1 part and stirring.

Using the SMC and thermosetting coating material prepared as described above, a molded product was obtained by the following procedure. 30 cm x 30 with the upper mold heated to 150 ° C and the lower mold heated to 150 ° C
Approximately 700g of the above SMC in a square flat metal mold.
I charged. The charged SMC had a thickness of about 4 mm. Then, at a pressure of 100 kg / cm ² , 1
Molding by press-molding for 00 seconds, then slightly opening the mold, injecting 10 ml of the thermosetting coating material, closing the mold again, and reheating and repressurizing at 80 kg / cm ² for 120 seconds. A thermosetting coating material was spread and cured on the entire surface of the obtained SMC to form a coating layer. Next, the mold was removed to obtain a coated molded product whose surface was coated with a coating layer having a thickness of about 100 μm.

A straight line reaching 11 bases (base) is drawn in parallel at a distance of 2 mm on the surface of the obtained molded product with a cutter knife, and 11 straight lines orthogonal to these straight lines are 2 mm. It was drawn at intervals to form a grid-like portion. Next, stick an adhesive tape (made by Sekisui Chemical Co., Ltd., product name: Cellotape) on the grid-shaped part, and then peel it off to remove the remaining number of squares in the grid, that is, the number of residuals of the coating layer that will not peel off. (Hereinafter, referred to as a cross-cut adhesion test). As a result, the ratio (adhesion) of the coating layer which did not peel off was 100 pieces / 100 pieces.

Example 2 The amount of the unsaturated polyester resin liquid used was 30 parts,
An SMC was prepared in the same manner as in Example 1 except that the amount of allyl isocyanate was 40 parts. A molded article having a coating layer was obtained in exactly the same manner as in Example 1 except that the obtained SMC was used. When the obtained molded product was subjected to a cross-cut adhesion test in the same manner as in Example 1, the ratio of the coating layer not peeling was 1
The number was 00/100.

Example 3 Except that 12 parts of allyl isothiocyanate (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 5 parts of allyl isocyanate,
An SMC was manufactured in exactly the same manner as in Example 1. Thereafter, the SMC was used and the subsequent steps were performed in exactly the same manner as in Example 1 to obtain a molded article with a coating layer. A cross-cut adhesion test was conducted on the obtained molded article with the coating layer in the same manner as in Example 1. As a result, the rate of the coating layer not peeling was 100 pieces / 100 pieces.

Comparative Example 1 An SMC was prepared in the same manner as in Example 1 except that allyl isocyanate was not used. Using this SMC, a coated molded article was obtained in the same manner as in Example 1 except for the other steps. About the obtained coated molded article, Example 1
When a cross-cut adhesion test was conducted in the same manner as above, the ratio of the coating layer not peeling was 31 pieces / 100 pieces.
Table 1 below shows the composition of the thermosetting resin compositions for forming the substrates for Examples 1 to 3 and Comparative Example 1 and the results of the cross-cut adhesion test.

[0037]

[Table 1]

Claims (2)

[Claims] 1. A thermosetting resin composition used for the base material in an in-mold coating molding method for forming a coating layer by coating a thermosetting coating material on a base material in a mold, comprising: In-mold coating molding heat containing a compound having a copolymerizable double bond and an isocyanate group in the molecule, and / or a compound having a copolymerizable double bond and an isothiocyanate group in the molecule Curable resin composition. 2. A coated molded article comprising a base material and a coating layer formed on the base material, wherein the base material comprises the thermosetting resin composition according to claim 1.