JPH0212181B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to so-called fiber-reinforced plastic bathtubs made of unsaturated polyester resin and reinforcing materials, and particularly to reinforced plastic bathtubs (hereinafter referred to as FRP bathtubs) having a gel coat layer on the surface of glass fiber-reinforced plastic bathtubs, which are the mainstream. It is. The gel coat resin for FRP bathtubs has heat resistance,
Performance requirements include water resistance, crack resistance, and high hardness to prevent scratches on the surface. Furthermore, in order to obtain a colorful FRP bathtub, the gel coat resin is required to be easily colored with pigments and to have good pigment dispersibility in order to stabilize the colored tone. Conventionally, unsaturated polyester resins (for example, isophthalic acid-based or bisphenol-based unsaturated polyester resins) have been used as gel coat resins for FRP bathtubs, but unsaturated polyester resins generally have a low elongation rate when they have good heat resistance and water resistance. becomes small and brittle, resulting in poor crack resistance. On the other hand, if the elongation rate is increased to improve crack resistance, the heat resistance and water resistance will deteriorate, and the hardness will decrease, making it difficult to satisfy all the performance requirements for a gel coat layer in an FRP bathtub. Furthermore, examples of resins having good heat resistance, water resistance, and crack resistance include epoxy acrylate resins. However, epoxy acrylate resin has poor pigment dispersibility compared to conventional unsaturated polyester resin, resulting in uneven coloring and color separation, making it fatal as a gel coat resin for FRP bathtubs. It has some disadvantages. The present inventors have arrived at the present invention as a result of intensive research to improve these drawbacks of conventional resins for use in gel coat layers of FRP bathtubs. That is, by using a specific resin for the gel coat layer, the present invention has a long life that is resistant to blistering and cracking even when boiled in water for a long time, and is resistant to scratches.Moreover, colorful coloring is easy and there is no uneven color. The purpose is to provide an FRP bathtub with high commercial value and no color separation. That is, the first invention is based on the general formula (a) (However, in the formula, R ₁ and R ₂ each represent hydrogen or a methyl group and may be the same or different, A represents an alkylene group having 2 to 4 carbon atoms, and m and n
each represents an integer satisfying 2≦n+m≦10. ) consisting of 100 parts by weight of (meth)acrylate (A) and 10 to 100 parts by weight of polymerizable monomer (C) (meth)
This invention relates to a reinforced plastic bathtub having a gel coat layer on its surface using acrylate resin (1). Further, the second invention is based on the general formula (a) (However, in the formula, R ₁ and R ₂ each represent hydrogen or a methyl group and may be the same or different, A represents an alkylene group having 2 to 4 carbon atoms, and m and n
each represents an integer satisfying 2≦n+m≦10. ) 100 parts by weight of (meth)acrylate (A),
This invention relates to a reinforced plastic bathtub having a gel coat layer on its surface using a (meth)acrylate resin () consisting of 100 to 700 parts by weight of an unsaturated polyester (B) and 40 to 800 parts by weight of a polymerizable monomer (C). (Meth)acrylate (A) used in the present invention
is represented by the above-mentioned general formula, and a typical example of its production method includes a reaction method according to a two-step process as shown below. First step: hydroxyalkyl etherification step of divalent phenol (a) 3 to 5 moles of alkylene oxide (b) per mole of divalent phenol (a), if necessary, (1) triethylamine, triethanolamine,
Amine compounds such as trimethylbenzylammonium chloride; Lewis acids such as boron trifluoride and tin tetrachloride; alkali metal compounds such as sodium, lithium, and potassium; reaction catalysts such as alkaline earth metal compounds such as calcium and magnesium (2) Acetone, tricrene, dichloromethane, methyl ethyl ketone, methyl isobutyl ketone,
A process of converting the hydroxyl group of divalent phenol (a) into a hydroxyalkyl ether at room temperature or under heating in the presence of an organic solution such as benzene, toluene, xylene, etc. 2nd step: Esterification step per equivalent of the reaction product (c) obtained in the 1st step
More than 0.9 equivalents of acrylic acid and/or methacrylic acid or their acid chlorides are added as necessary to (1) a reaction catalyst such as para-toluenesulfonic acid, sulfuric acid, Lewis acids, titanate esters, etc. (2) First step (3) Tertiary amines such as triethylamine and pyridine; organic solvents such as those exemplified in (3) tertiary amines such as triethylamine and pyridine; A step of converting the hydroxyl group of the reaction product (c) obtained in step 1 into an ester of acrylic acid and/or methacrylic acid. However, the present invention is not dependent on such a method for producing (meth)acrylate (A). In addition, in the general formula (a) representing (meth)acrylate (A), if m and n are outside the range of 2≦n+m≦10, an excellent gel coat layer cannot be obtained. It is desirable that the unsaturated polyester (B) has good water resistance, and preferred raw materials for the unsaturated polyester for this purpose include isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, and endomethylene as saturated polybasic acids. Examples include tetrahydrophthalic anhydride, and polyhydric alcohols include propylene glycol, 1,3-butanediol, neopentyl glycol, hydrogenated bisphenol A, and 2,2-di(4-hydroxypropoxyphenyl)propane. can be mentioned. Examples of the polymerizable monomer (C) include vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, methyl (meth)acrylate, and ethyl (meth)acrylate. The (meth)acrylate resin () used as the gel coat layer in the first invention consists of 100 parts by weight of (meth)acrylate (A) and 10 to 100 parts by weight of a polymerizable monomer (C). Polymerizable monomer (C)
If the ratio exceeds 100 parts by weight, curing shrinkage will increase, and cracks may occur in the gel coat layer due to curing shrinkage. In addition, the (meth)acrylate resin () used as the gel coat layer in the second invention is
100 parts by weight of acrylate (A), unsaturated polyester
It consists of 100 to 700 parts by weight of (B) and 40 to 800 parts by weight of polymerizable monomer (C). (meth)acrylate
The combined use of (A) and the unsaturated polyester (B) is advantageous in terms of cost compared to the case where the unsaturated polyester (B) is not used together. Unsaturated polyester (B)
If the ratio is less than 100 parts by weight, the effect of the combination will not be exhibited, and if the ratio exceeds 700 parts by weight (meta)
The properties of acrylate (A) are not exhibited and an excellent gel coat layer cannot be obtained. In general, in FRP bathtubs, the gel coat layer absorbs water when water is boiled, the water permeates, and the hot water affects the FRP lining layer that reinforces the gel coat layer, so it is not used for the FRP lining layer. Resins are required to have water resistance and heat resistance. However, the (meth)acrylate resin () or (meth)acrylate resin () used in the present invention has excellent heat resistance, water resistance, and crack resistance. When (meth)acrylate resin () is used as the gel coat layer of an FRP bathtub, compared to unsaturated polyester resin or epoxy acrylate resin, water absorption due to water boiling is extremely low, and the influence of hot water on the FRP backing layer is reduced. It almost disappears. Therefore, the unsaturated polyester resin used for the FRP backing layer is not particularly required to have water resistance, and it is possible to select an unsaturated polyester resin with a high elongation rate and good crack resistance. A structure with good crack resistance can be obtained. Furthermore, (meth)acrylate resin () and (meth)acrylate resin () have the feature of excellent pigment dispersibility. Next, examples are shown below to help understand the present invention, but the present invention is not limited thereto. In the examples, "parts" and "%" refer to "parts by weight" and "% by weight" unless otherwise specified. Reference Example 1 In a flask, add 162 parts of "Uniol DA-350" (addition reaction product of bisphenol A and ethylene oxide manufactured by NOF Corporation, addition molar ratio ethylene oxide/bisphenol A = 2.3) and toluene.
500 parts, methacrylic acid 130 parts, hydroquinone
Adding 0.1 part and 4 parts of para-toluenesulfonic acid, esterification was carried out at 105 to 110°C while removing toluene-water azeotrope in a fractionating tube, followed by washing with water and removing volatile components to form "UNIOL DA-". 350” of methacrylate was obtained. Dissolve 100 parts of this methacrylate in 30 parts of styrene to create methacrylate resin.
(1). Reference Example 2 In a flask, add 200 parts of "Uniol DA-400" (addition reaction product of bisphenol A and ethylene oxide manufactured by NOF Corporation, addition molar ratio ethylene oxide/bisphenol A = 4.0) and toluene.
500 parts, methacrylic acid 130 parts, hydroquinone
0.1 part and 4 parts of para-toluenesulfonic acid were added, and methacrylate was obtained by the same reaction method as in Example 1. 100 parts of this methacrylate was dissolved in 30 parts of styrene to obtain methacrylate resin (2). Reference Example 3 In a flask, add 200 parts of "Uniol DB-400" (addition reaction product of bisphenol A and propylene oxide manufactured by NOF Corporation, addition molar ratio propylene oxide/bisphenol A = 3.0) and toluene.
500 parts, methacrylic acid 130 parts, hydroquinone
0.1 parts and 4 parts of para-toluenesulfonic acid were added, and 100 parts of methacrylate obtained in the same manner as in Example 1 was dissolved in 10 parts of styrene to obtain methacrylate resin (3). Reference Example 4 532 parts of propylene glycol, 840 parts of hydrogenated bisphenol A, 498 parts of isophthalic acid and 686 parts of maleic anhydride were heated at 190 to 210°C in an inert gas flow.
After esterification to an acid value of 30, the mixture was dissolved in 1,500 parts of styrene containing 0.4 parts of hydroquinone to obtain a bisphenol-based unsaturated polyester resin (1). Reference Example 5 In a flask, add a bisphenol type epoxy resin with an epoxy equivalent of 473 (manufactured by Ciba Co., Ltd., “Araldite #
6071”) 615 parts, bisphenol type epoxy resin with an epoxy equivalent of 185 (manufactured by Ciba, “Araldite
GY-260") 130 parts, 176 parts of methacrylic acid, 0.1 part of hydroquinone, and 3.2 parts of triethylamine were charged and reacted at 110°C for 5 hours while introducing air, and the reaction was terminated when the acid value reached 7. Then, 650 parts of styrene monomer was added to the system containing the reaction product to obtain vinyl ester resin (1). Example 1 Each methacrylate resin, unsaturated polyester resin, and vinyl ester resin obtained in Reference Examples 1 to 5 100 parts each of methyl ethyl ketone peroxide (peroxide content 55%) 1
parts and cobalt octenoate (metal content 8%)
It was cured using 0.3 parts to obtain a casting plate with a thickness of 3 mm. Tensile strength, elongation rate and water boiling of this cast plate
The water absorption rate after 1000 hours was measured according to JIS K 6911. The results were as shown in Table 1.

[Table] Example 2 Using each resin obtained by mixing each methacrylate resin obtained in Reference Examples 1 to 2 and 4 and an unsaturated polyester resin in the proportions shown in Table 2, A cast plate was prepared in the same manner as above, and its performance was then evaluated. The results were as shown in Table 2.

[Table] Example 3 (gel coat formulation) Resin 100 parts Titanium oxide 15 parts Blue pigment 0.8 parts Silicic anhydride fine powder 2.5 parts Styrene 7 parts Methyl ethyl ketone peroxide 1.5 parts (Peroxide content 55%) Cobalt octoate 0.3 parts (Metal content: 8%) Using a gel coat formulation consisting of the above composition, spray coat the gel coat layer to a thickness of 0.4 mm, and after curing, unsaturated polyester resin (manufactured by Nippon Shokubai Chemical Co., Ltd.) “Epolack N-
350PTMY”), Surf Ace pine (30p) and chopped strand pine (#380) to obtain reinforced plastic bathtubs.
Table 3 shows the resin used for the gel coat layer, the appearance of the reinforced plastic bathtub, and the change in appearance when the bathtub was boiled in water.

[Table] As described above, the (meth)acrylate resin () or (meth)acrylate resin () of the present invention
It can be seen that reinforced plastic bathtubs using this material have excellent heat resistance, water resistance, and crack resistance.

Claims (1)

[Claims] 1 General formula (a) (However, in the formula, R ₁ and R ₂ each represent hydrogen or a methyl group and may be the same or different, A represents an alkylene group having 2 to 4 carbon atoms, and m and n
each represents an integer satisfying 2≦n+m≦10. ) consisting of 100 parts by weight of (meth)acrylate (A) and 10 to 100 parts by weight of polymerizable monomer (C) (meth)
A reinforced plastic bathtub with a gel coat layer on its surface using acrylate resin. 2 General formula (a) (However, in the formula, R ₁ and R ₂ each represent hydrogen or a methyl group and may be the same or different, A represents an alkylene group having 2 to 4 carbon atoms, and m and n
each represents an integer satisfying 2≦n+m≦10. ) 100 parts by weight of (meth)acrylate (A),
A reinforced plastic bathtub having a gel coat layer on its surface using a (meth)acrylate resin () consisting of 100 to 700 parts by weight of an unsaturated polyester (B) and 40 to 800 parts by weight of a polymerizable monomer (C).