JPH0448327B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention mainly relates to the production of molded products that require aesthetic appeal, such as bathtubs, table tops, and washstands. [Prior Art and Problems] In order to cure radical-curable resins such as polyester resins and vinyl ester resins at or near room temperature, organic peroxides such as Kent peroxide and cobalt organic acids are required. The combined use of salts (naphthenic acid, octylic acid) is well known and widely used. However, when cobalt naphthenate is used, for example, it has the undesirable drawback that molded products and coatings yellow over time. For example, in the case of artificial marble, which is required to have an extremely light color, discoloration during use must be avoided since this will greatly reduce its commercial value. However, even though the use of cobalt salts is undesirable, until now it has not been possible to cure resins at room temperature without using cobalt salts. [Means and effects for solving the problem] The present inventors have made numerous attempts to avoid the use of cobalt salts, and have found that it is optimal to use a photocuring method in order to avoid coloring when cured at room temperature. This led to the present invention. Initially, photocuring methods were very effective in curing gel coats, but other drawbacks were discovered. The problem is that if it is sufficiently photocured to exhibit sufficient physical properties as a gel coat, it tends to peel off from the next FRP lamination or casting layer. This drawback can be prevented by polishing the gel coat to improve its adhesion, but this significantly increases the number of man-hours and is disadvantageous in terms of productivity. Therefore, in order to eliminate this drawback, the present inventors proposed that light curing be carried out to the desired degree of curing using an organic peroxide in combination, and final curing should be carried out by heat curing using peroxide. . However, as a result of further research, it was found that when a photocurable resin is used for the gel coat and the glass mat layer used in conjunction with it if necessary, acryloyl or methacryloyl groups (hereinafter referred to as It was discovered that the drawback of occurrence of peeling can be overcome by using an unsaturated polymer having a (meth)acryloyl group through an ester bond or a urethane bond, thereby completing the present invention. Since curing with light can be easily controlled, it is easy to adjust the curing of the gel coat and the laminated portion following the gel coat at any necessary stage. As the gel coat resin, a radical curing resin that can be photocured is used. Examples include (1) polyester resins, (2) vinyl ester resins (epoxy acrylates), and (3) unsaturated polymers having (meth)acryloyl groups in their side chains. (1) Polyester resin contains an α-β unsaturated polybasic acid or its acid anhydride as a necessary component, and the unsaturated polyester obtained by esterifying it with a polyhydric alcohol using a saturated acid in combination with a copolymer such as styrene. It is in dissolved form in a polymerizable monomer. For use in the present invention, the polyhydric alcohol component is preferably a component that imparts hot water resistance to the cured resin, such as neopentyl glycol, hydrogenated bisphenol A, or bisphenol A propylene oxide adduct; isophthalic acid and terephthalic acid are preferable. (2) Vinyl ester resins are synthesized by reaction of epoxy groups and carboxyl groups using epoxy resins and (meth)acrylic acid. As the epoxy resin, a bisphenol-glycidyl ether type resin having a molecular weight of 350 to 700 is suitable. In addition to (meth)acrylic acid, it is also practical to use polybasic acids or their acid anhydrides together. The form utilized in the present invention is dissolved in a copolymerizable monomer such as styrene. The appropriate amount of styrene is 30 to 50 (%). (3) An unsaturated polymer having a (meth)acryloyl group in the side chain has a molecular weight of 5000 or more and has one or more (meth)acryloyl groups in the polymer side chain via a urethane bond or an ester bond. Examples include monomer solutions of unsaturated polymers. This unsaturated polymer is used as a casting resin, the details of which will be described later. A photopolymerization initiator is required in order to make the gel coat resin photocurable by using it in combination with these radical curable resins. Various types of photopolymerization initiators can be used, but from the perspective of avoiding coloring of the cured gel coat layer, hydrogen abstraction types that use amines in combination are not suitable, and cleavage type radical generation sources are not suitable. good. Examples include (a) Acetophenone derivatives, such as 2-hydroxy-2-methyl-1 phenylpropan-1-one (Merck & Co., Ltd. "Darocure 1173"); (b) Benzyl ketals, such as hydroxy-cyclohexyl-phenyl ketone ( Ciba Corporation “Irgacure184”) is mentioned. If the gel coat layer is a resin with good hot water resistance,
Since this protects the surface of the molded product, any resin used for casting can be used as long as it has good adhesive properties. A feature of the present invention is that after photo-curing the gel coat layer and the laminated portion that follows it, a casting resin with good adhesion to the gel coat layer is used as a casting resin with a molecular weight of 5000 or more.
The purpose of this invention is to use an unsaturated polymer having more than one (meth)acryloyl group. Examples of the types of unsaturated polymers for this purpose include the following types. (1) An unsaturated polymer that has a (meth)acryloyl group in its side chain via a urethane bond by reacting a polymer with a hydroxy group in its side chain with an unsaturated isocyanate having a (meth)acryloyl group. The most typical unsaturated isocyanate is isocyanate ethyl methacrylate (abbreviated as IEM) shown below. Alternatively, reaction products of diisocyanates and unsaturated monoalcohols having (meth)acryloyl groups are also used. An example of this is as follows. 2,4-tolylene diisocyanate 2-hydroxyethyl methacrylate Unsaturated Isocyanate As the diisocyanate used in this case, it is useful to use diisocyanates in which the two isocyanate groups have different reactivities, such as 2,4-tolylene diisocyanate and isophorone diisocyanate. . There is no need to limit the type of polymer having a hydroxyl group; for example, phenoxy resin,
Examples include cellulose esters, cellulose ethers, and vinyl butyral resin.
Generally, a copolymer of a monomer having a hydroxyl group and another monomer is advantageous in terms of cost and ease of handling. These polymers are conveniently reacted with unsaturated isocyanates in the form of monomer solutions;
If it is difficult to dissolve in styrene, such as phenoxy resin, it is dissolved in a good solvent such as methyl ethyl ketone and then reacted with unsaturated isocyanate to form a monomer-soluble form. will be replaced. (2) React (meth)acrylic acid with a polymer that has epoxy groups in its side chains. It has a so-called vinyl ester resin structure. Conversely, glycidyl methacrylate can also be reacted with a carboxy group-containing polymer. Polymers having epoxy groups in side chains are usually obtained by copolymerizing glycidyl methacrylate with other monomers. In this case, tertiary amine, quaternary ammonium,
The combined use of reaction catalysts such as phosphines is necessary. (3) A polymer having an acid anhydride group in its side chain is reacted with an unsaturated monoalcohol having a (meth)acryloyl group. Furthermore, it is also possible to react with an unsaturated epoxy compound. As the component having an acid anhydride group, copolymerizable acid anhydrides such as maleic anhydride and itaconic anhydride are generally used. Curing of these unsaturated polymers for casting is carried out in combination with an organic peroxide. The cast layer is usually formed with a filler mixed therein. Glass powder, aluminum hydroxide, etc. are commonly used as fillers. In the composition and method of the present invention, a coloring agent, a mold release agent, a thixotropy imparting agent,
Of course, a thermoplastic polymer or the like can also be used in combination. Next, in order to further explain the present invention, Examples are shown below. Example 1 Production of vinyl ester resin (A) for gel coat and gel coat () Epoxy resin and bisphenol type liquid resin with epoxy equivalent of 175 were placed in a separable flask equipped with a stirrer, reflux condenser, gas inlet tube, and thermometer. (Yuka Ciel Co., Ltd. Epicote 827) and 75 g of inphthalic acid were charged at 170-190℃ in a nitrogen stream.
After reacting for 3 hours, the temperature was lowered to 135°C, and 0.3 g of hydroquinone, 86 g of methacrylic acid, 0.5 g of trimethylbenzylammonium chloride, and 1.5 g of chromium naphthenate were added, and the mixture was heated to 135°C in a nitrogen stream.
After reacting at 135℃ for 3 hours, add 100g of styrene and continue the reaction at 115-120℃ for 1 hour.
The acid value was 9.1. At this stage, styrene 380
g was added to synthesize vinyl ester resin (A) for gel coat. This resin has a Hazen color number of 350,
The viscosity was 11.4 poise. (Formation of gel coat layer) Add 5 parts of Erosil R-200 to 100 parts by weight of vinyl ester resin (A) and knead with a triple roll.
Added thixotropic properties. To 100 parts of this resin, 3 parts of "Darocure #1173" manufactured by Merck & Co., Ltd. as a photopolymerization initiator was added to produce a gel coat of the present invention, which was designated as Gel Coat (). Production of side chain double bond type unsaturated polymer (B) Styrene was placed in a two-separable flask equipped with a stirrer, reflux condenser, thermometer, and gas inlet tube.
624g, 2-hydroxyethyl methacrylate 130
g, 5 g of t-butyldodecyl mercaptan, and the polymerization rate was 60-65 at 130-135°C in a nitrogen stream.
(%) After polymerization, hydroquinone 0.3
g, 312 g of styrene, and 100 g of ethylene glycol dimethacrylate, switch to air flow, and lower the temperature to 60°C. Isocyanate ethyl methacrylate 155g,
Add 3g of dibutyltin dilaurate and heat to 60-65℃ for 5 minutes.
After reacting for a period of time, infrared analysis revealed that the isocyanate groups were burned out. An unsaturated polymer (B) having a Hazen color number of 50 and a viscosity of 13.7 poise and having a methacryloyl group in the side chain via a urethane bond was obtained. The average molecular weight of the polymer component was approximately 39,000. On a 30cm x 30cm x 5m/m glass plate coated with a release agent, apply gel coat () to a thickness of 0.5m/m using a bar coater, wait until the coated surface is even, and apply an output of 250W. When irradiated for about 30 minutes at a position 30 cm below a sun lamp (manufactured by Stanley Electric Co., Ltd.), the gel coat layer was cured to a Barcol hardness of about 39. (Casting, heat curing) With the obtained gel coat layer on one side, another FRP with a thickness of 2 m/m and using three layers of white colored glass mat was arranged at an interval of 10 m/m. During this time, as a casting resin, 100 parts by weight of unsaturated polymer (B) (the same applies hereinafter), 170 parts of Fritz manufactured by Nippon Ferro Co., Ltd., 10 parts of styrene, and 1.5 parts of Perbutyl pV manufactured by Nippon Oil & Fats Co., Ltd. were added, The uniformly mixed resin was defoamed and cast. It was heated and cured at 60°C for 2 hours and at 80°C for 4 hours. When the mold was removed after curing, a molded product (A) with a transparent gel coat layer on the surface was obtained. Comparative example: Vinyl ester resin (A) as casting resin
To 100 parts, 200 parts of Nippon Ferro Co., Ltd. frit, 15 parts of styrene, and 1.5 parts of Parkadox #16 were added, and the resin was uniformly kneaded, defoamed, cast, and then heated at 60°C for 2 hours together with the gel coat layer. , and heat-cured at 80°C for 4 hours. The obtained molded product was designated as molded product (b). Each molded product was cut into 15cm x 30cm pieces, placed in a boiling test container with four 10cm diameter circular holes on one side, with the gel coat layer facing inside, and subjected to a boiling test at a temperature of 98 to 99°C. I went. The results are shown in Table 1.

【table】

〔Effect of the invention〕

As described above, the present invention combines a photopolymerization initiator with a photocurable radical curable resin, and uses an unsaturated polymer containing a (meth)acryloyl group in the side chain as a casting resin. Casting of the backing layer without completely photo-curing the gel coat layer,
By performing heat curing, an excellent molded product without yellowing or peeling of the gel coat layer can be obtained.

Claims (1)

[Claims] 1. In the mold, (a) selected from polyester resin (), vinyl ester resin (), and unsaturated polymer () having an acryloyl group or methacryloyl group in the polymer side chain with a molecular weight of 5000 or more via an ester bond or a urethane bond. Applying a gel coat mixed with (b) a photopolymerization initiator to at least one type of photocurable radical curable resin, curing the gel coat to a desired degree of hardening by irradiating light, and backing with glass fiber. A method for manufacturing a molded article, which comprises casting the unsaturated polymer (2) to a required thickness, with or without casting, and then heating and curing the gel coat layer and the casting layer.