JPH0542930B2 - - 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 Issues] Radical-curable resins, such as polyester resins and vinylester resins, can be cured by heating, but attempting to do so industrially requires large heating equipment and is costly, so it is not possible. There is a need for a method of curing at as low a temperature as possible, preferably at room temperature. However, in order to cure these curable resins at or near room temperature, organic peroxides such as ketone peroxide are used as curing agents, and cobalt organic hydrochloric acid (naphthenate, octyl It is necessary to use it in combination with an acid salt). 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 is not desirable because its commercial value will be greatly reduced. In particular, since gel coat constitutes the surface layer of a resin molded article, discoloration of this layer must be avoided. However, although the use of cobalt salts is undesirable from the standpoint of yellowing of the resin, until now, effective room-temperature or low-temperature curing of the resin has not been possible without the use of cobalt salts. . In addition, the water resistance of the gel coat layer is also different from that of conventional resins.
This was not necessarily sufficient, and the crack resistance and transparent appearance of the cast part were still insufficient. [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 in order to prevent coloring during room temperature curing, it is necessary to accelerate the curing of peroxide-based curing agents. without using organic acid salts of cobalt as agents.
I learned that it is best to use the photocuring method,
This led to the present invention. Although the photocuring method has been very effective in curing gel coats, other drawbacks have been discovered. The problem is that when it is completely photocured to show 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 avoid this drawback, instead of completely curing with light curing, photo curing is used to advance the curing to an intermediate curing stage, and the final complete curing (cure) is performed using organic peroxide. I discovered that I could achieve my goals by making things work. In addition, because we used a radically curable polymer with a molecular weight of 5000 or more and one or more (meth)acroyl groups in the side chain for the gel coat layer () and the casting layer (), the water resistance of the gel coat layer and the casting layer The crack resistance of the layer and the transparent appearance have also been improved. Since the curing by light in step () of the present invention can be easily controlled, the curing of the gel coat or the subsequent laminated portion can be adjusted to the necessary degree. After the gel coat layer or, if necessary, the laminated portion has been photocured, casting is performed using a radical curing resin containing a radical curing agent, and this is heated and cured together with the gel coat layer. As a result, the casting part and the gel coat part are cured and bonded together, and a strong molded product without peeling can be obtained. Heating temperature for curing is 100℃
The temperature below is preferably about 70 to 80°C. The gel coat uses a radical curing resin that can be photocured and cured with organic peroxide. In particular, in the present invention, when the molecular weight is 5000
A monomer solution of a radically curable polymer having one or more (meth)acryloyl groups in the polymer side chain is suitable. By selecting this polymer, the water resistance of the gel coat layer can be improved. This unsaturated polymer having a (meth)acryloyl group in its side chain (hereinafter simply referred to as unsaturated polymer) is synthesized by the following method. (i) A polymer having a hydroxyl group in its side chain,
An unsaturated isoyanate having a methacryloyl group is reacted. (ii) A polymer having an epoxy group in its side chain is reacted with (meth)acrylic acid. (iii) A polymer having an acid anhydride group in its side chain is reacted with an unsaturated alcohol having a (meth)acryloyl group. This is shown in the formula below. (a) Urethane type unsaturated polymer Side chain hydroxyl group polymer isocyanate ethyl methacrylate (unsaturated isocyanate) Urethane type unsaturated polymer (b) Vinyl ester type unsaturated polymer Side chain epoxy group polymer methacrylic acid Vinyl ester type unsaturated polymer (c) Ester side unsaturated polymer Ester-type unsaturated polymers The raw materials for unsaturated polymers are all synthesized by polymerizing monomers, but for urethane-type unsaturated polymers, side-chain hydroxy polymers such as cellulose derivatives can also be used, but they are expensive and durable. From the viewpoint of boilability, vinyl monomer polymerization types are preferred. Existing methods can be used for polymerization, but direct polymerization is convenient in terms of handling of subsequent steps. These casting unsaturated polymers are used as a mixture with a monomer solution, for example styrene monomer. The mixing ratio is 30~30 depending on the concentration of unsaturated polymer.
70%, preferably 40-60%. The above-mentioned unsaturated polymers are used for the gel coat in step () and the cast layer in step (). Further, polyester resins and vinyl ester resins can also be used in combination if necessary. In order to make these radically curable unsaturated polymers photocurable as the gel coat resin of the present invention, it is necessary to use a photopolymerization initiator together. 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 generators are preferable. . Examples thereof include (a) acetophenone derivatives, such as 2-hydroxy-2-methyl-1-phenylpropane-1;
-one (Merck & Co. “Darocure #1173”) (b) Benzyl ketals, e.g. hydroxy-
Examples include cyclohexyl phenyl ketone (Ciba "Irgacure #184"). The gel coat resin of the present invention uses an organic peroxide in combination for final complete curing. The type of organic peroxide used for this is not particularly specified, but in reality the operation to form the cast layer is often performed at a temperature of 100°C or less, so it is kept at a relatively low temperature. For example, a type that decomposes at 80°C or lower is desirable. Examples include ketone peroxides, peroxyketals, peroxycarbonates, diacyl peroxides, and peroxyesters whose decomposition temperature is below 120°C to obtain a half-life of 10 hours.
Among these, peroxycarbonate and peroxy esters are advantageous, and if appropriate curing temperature and handling safety are taken into account, bis(t-butylcyclohexyl) peroxydicarbonate (Kayaku Nouri) is preferred. Company “Parkadox #16”) is suitable. Combination use with other peroxides is also possible. When casting and curing resin, a filler is usually used in combination with the casting resin to provide a suitable degree of transparency and to prevent cracks due to heat generation during curing and molding. Glass powder, aluminum hydroxide, etc. are generally used as fillers. Furthermore, in the composition and method of the present invention, it is of course possible to use a coloring agent, a mold release agent, a thixotropy imparting agent, a thermoplastic polymer, etc. in combination, if necessary. Next, in order to further explain the present invention, Examples are shown below. Example 1 (Synthesis of gel coat resin (A) (urethane type unsaturated polymer A)) Styrene was placed in a two-separable flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer.
Weighed out 936 g and 130 g of 2-hydroxyethyl methacrylate (HEMA), and heated them at 120°C in a nitrogen stream for 6 hours.
After heating for an hour, the reaction rate reaches about 42%, and the free
As a result of glass chromatography analysis, HEMA was determined to be approximately 14% of the initial amount. Add 0.2g of hydroquinone and lower the temperature to 70℃.
Switching to air flow, 140 g of isocyanate ethyl methacrylate and 3 g of dibutyltin dilaurate were added, and the mixture was reacted at 70° C. for 5 hours. As a result of infrared analysis, it was confirmed that free isocyanate had disappeared. A urethane-type unsaturated polymer (A) with a Hazen color number of 30 and a viscosity of 11.4 poise was obtained. (Production of casting resin (B) (vinyl ester type unsaturated polymer B)) Styrene was added to a two-separable flask equipped with a stirrer, reflux condenser, thermometer, and gas inlet tube.
When 936g of glycidyl methacrylate and 142g of glycidyl methacrylate were charged and heated at 120 to 122℃ for 6 hours in a nitrogen stream,
The polymer content reached approximately 43%, and the residual rate based on the amount of glycidyl methacrylate charged was approximately 16%. This includes 0.3g of hydroquinone and 95g of methacrylic acid.
g, and 5 g of trimethylbenzylammonium chloride were added, the temperature was lowered to 100-105°C, and the reaction was carried out in an air stream for 12 hours. As a result of infrared analysis, it was determined that the absorption of epoxy groups had disappeared. In addition, ethylene glycol dimethacrylate
A casting resin (B) having a Hazen color number of 100 and a viscosity of 14.1 poise was obtained by adding 130 g. (Formation of gel coat layer) 100 parts of unsaturated polymer (A), 10 parts of ethylene glycol dimethicrylate, 3 parts of Erosil R-200, silane coupling agent (Shin-Etsu Chemical Co., Ltd. KBM)
-503) as a photoinitiator, Merck & Co., Ltd.
Add 2 parts of “Darocure #1173” and 1 part of organic peroxide (Kayaku Nouri Co., Ltd. “Parkadox #16”),
A photocurable gel coat composition (a) was obtained by roll kneading. As a comparative example, a gel coat composition (b) was prepared by adding 0.1 part of cobalt naphthenate (6% Co) to 100 parts of the unsaturated polymer (A). Apply gel coat to a thickness of 0.5 mm on a 30 cm x 30 cm x 5 mm glass plate coated with a release agent using a bar coater, wait until the coated surface is even, and then apply a 250 W sun lamp ( Stanley Electric Co., Ltd.
After approximately 15 irradiations at a distance of 30 cm below the gel coat (manufactured by Manufacturer Co., Ltd.), the gel coat layer was hardened to the extent that it was dry to the touch. (Casting, heating, and curing) FRP with a cured gel coat layer on one side and 2 mm thick glass matte colored white on the other side.
100 parts of casting resin (B) and Nippon Ferro's frit B-
Mix 200 parts of Nippon Oil Co., Ltd. Perbutyl PV and 1.5 parts of Nippon Oil & Fats Co., Ltd. Perbutyl PV.
Cure for 2 hours. A molded article using the gel coat composition (a) was designated as a molded article (a), and a molded article using the gel coat composition (b) was designated as a molded article (b). Both molded products were cut into 15cm x 15cm pieces, placed in a boiling test container with four 10cm diameter circular holes on one side with the gel coat layer on the inside, and boiled at a temperature of 98 to 99°C. I went there. The results are shown in Table 1. As can be seen from this table, the present invention, which does not use cobalt naphthenate, showed extremely excellent performance.

[Table] Example 2 The vinyl ester resin type unsaturated polymer (B) used for casting in Example 1 was used for gel coat. Polymer (B) 100 parts, Erosil 3 parts, coupling agent 0.5
Ciba's “Irgacure” is used as a photopolymerization deactivator.
Knead 2 parts of #181” and 1 part of Perbutyl PV,
This was designated as gel coat composition (c). (Casting resin (C) (ester type unsaturated polymer)
synthesis) stirrer, heated dropping funnel, reflux condenser,
A two-separable flask equipped with a thermometer equipped with a gas inlet tube was charged with 936 g of styrene, and 98 g of molten maleic anhydride was added dropwise over 3 hours at a temperature of 120°C, followed by keeping the temperature at the same temperature for an additional 1.5 hours. Then 2-hydroxyethyl methacrylate
200 g, dibutyltin dioxide 5 g, and hydroquinone 0.1 g were added, and the mixture was reacted at 85 to 90°C for 22 hours.
Casting resin (C) with Hazen color number 50 and viscosity 5.9 poise
was gotten. As a result of infrared analysis, approximately 80 of the acid anhydride groups
% was determined to be ring-opened. (Formation, casting, heating, and curing of gel coat layer) After coating and photocuring the gel coat composition (c) under the same conditions as in Example 1, a #360 silane-treated glass mat was further placed, and the gel coat composition was coated. After impregnating and degassing (c), it was photocured in the same manner. FRP colored white is used as a backing layer, and 100 parts of casting resin (C), 180 parts of frit, and 2 parts of Perkyure 0 (t-butylperoxy-2-ethylhexanate) manufactured by NOF Corporation are kneaded. the thickness of 10
It was cast into a mold of 1.0 mm in size, initially cured at 80°C for 2 hours, and then removed from the mold. This was cut and a boiling resistance test was conducted in the same manner as in Example 1. Even after the 1000 hour boiling test, no abnormality was observed in the appearance of the surface gel coat layer.

Claims (1)

[Claims] 1 ()(1) As a photocurable resin (a) A radically curable polymer having one or more (meth)acryloyl groups in the side chain with a molecular weight of 5000 or more (b) A photopolymerization initiator (c) Applying a composition mixed with an organic peroxide and substantially free of cobalt organic hydrochloric acid to a mold as a gel coat, and curing the gel coat to a desired degree of hardening by irradiating it with light; () A monomer solution of a radically curable polymer having one or more (meth)acryloyl groups in the side chain with a molecular weight of 5000 or more is cast with or without backing using glass fiber, and then a gel coat layer is formed. and a method for producing a molded article, which comprises heating and curing a cast layer.