JP3868444B2 - Resin composition for reinforcing layer formed on surface of acrylic resin molded article and acrylic resin product using the same - Google Patents

Description

The present invention relates to a resin composition for a reinforcing layer formed on the surface of an acrylic resin molded article and an acrylic resin product reinforced using the same.

  Acrylic resin molded products are excellent in transparency, gloss, surface hardness, weather resistance, heat resistance, etc., but they are not strong enough, and on the back side in applications such as bathtubs, pools, live fish tanks, wash basins, etc. Reinforced acrylic resin molded products in which a reinforcing layer is formed are widely used. In recent years, bathtubs are required to have high productivity, but the shape is complicated due to the demand for excellent design, making it difficult to ensure strength and hot water resistance that can be used. ing.

  Generally, an acrylic resin bathtub is manufactured by the following procedure. First, a transparent (clear) or colored acrylic sheet having a thickness of 4 to 8 mm is formed into a bathtub-shaped acrylic shell by vacuum forming. Next, in the case of a clear acrylic shell, a colored primer mainly composed of a vinyl ester resin is applied to the back surface for coloring or patterning, and then a reinforcing layer is formed thereon to obtain an acrylic resin bath. On the other hand, in the case of a colored acrylic shell, an acrylic resin bathtub is obtained by forming a reinforcing layer on the back surface without applying a primer.

For the reinforcing layer of the acrylic resin bathtub manufactured as described above, a liquid acrylic resin, vinyl ester resin or unsaturated polyester resin, in which reinforcing fibers are blended as necessary, is generally used. And since the performance of the acrylic resin bathtub such as strength and hot water resistance is greatly influenced by the adhesion between the acrylic shell or primer and the reinforcing layer, various reinforcing resins for improving the adhesion have been proposed. Yes.
Although liquid acrylic resin has good adhesion to the acrylic shell without primer applied, it has poor adhesion to the acrylic shell with primer applied, so when used for clear acrylic shell, it will reinforce the primer layer with long-term hot water use. There is a problem that peeling easily occurs between the layers (backing layers). In addition, the cost of the resin itself is high and disadvantageous in terms of economics, and there is an odor caused by the MMA (methyl methacrylate) monomer, and it falls under the Fire Service Act Article 2, Class 4, Class 1 petroleum. However, there is a problem in that there is a restriction in terms of storage amount, and it is difficult to add an amine-based curing accelerator in advance, so that it is necessary to add a curing accelerator immediately before molding.
When vinyl ester resin is used, there is a problem that whitening occurs on the acrylic shell surface because moisture tends to accumulate at the interface between the acrylic shell and the reinforcing layer as compared with liquid acrylic resin and unsaturated polyester resin. is there.
Although the unsaturated polyester resin has low resin cost and is excellent in economic efficiency, there is a problem that adhesion between the acrylic shell and the unsaturated polyester resin is low.

Therefore, in order to improve the adhesion between the acrylic shell and the unsaturated polyester resin, a low shrinkage imparting agent (styrene-vinyl acetate copolymer) and medium temperature are added to the unsaturated polyester resin composed of an unsaturated dibasic acid and a glycol component. The manufacturing method of the acrylic molded article using the unsaturated polyester resin composition which added the hardening | curing agent for shaping | molding is disclosed (for example, refer patent document 1).
However, when the bathtub obtained by the above manufacturing method is brought into contact with warm water for a long period of time, the chemical bonding force between the acrylic shell and the reinforcing layer is weak, which may cause poor adhesion. Furthermore, in resin transfer molding (RTM) molding methods for acrylic baths, etc., high cycle molding is required, and it is necessary to cure quickly, but if this is done, cracks and delamination will occur in the reinforcing layer at the initial stage of curing. There is also a problem that productivity is not improved.

JP 2003-170443 A

Acrylic resin bathtubs with a reinforcing layer are required to have no cracks in the reinforcing layer and the acrylic shell, no peeling between the reinforcing layer and the acrylic shell, no distortion on the acrylic shell surface, etc. The peeling of the acrylic shell can be confirmed from the observation of the cross section when the end of the acrylic bath is subjected to a cutting process called trimming after molding). Cracks and peeling are closely related to the rapid curability (high cycle productivity) of the resin. In other words, the faster the curing rate, the greater the shrinkage stress generated in the resin. This shrinkage stress is caused by cracks in the reinforcing layer, separation between the reinforcing layer and the acrylic shell, cracks in the acrylic shell, and stress in the reinforcing layer. This is because it is released in any form of absorption. Therefore, at the initial stage of curing, sufficient adhesion strength and strength and toughness that the reinforcing layer itself can absorb shrinkage stress are required.
In particular, the reinforcement layer of the acrylic resin bathtub is required to have hardness, strength, rigidity, heat resistance, hot water resistance, etc., but the emphasis on practical use is reinforcement after contact with hot water for a long period of time. The adhesion between the layer and the acrylic shell. For example, in the stage immediately after the molding, even if it is sufficiently adhered, it may cause peeling or swelling of the acrylic shell due to contact with hot water for a long time.

As mentioned above, none of the above-mentioned conventional resin compositions for reinforcing acrylic resin molded articles satisfy all excellent adhesion, economic efficiency and productivity with an acrylic shell or a primer applied to the acrylic shell. It was.
Accordingly, the present invention has been made to solve the above-described problems, and has excellent adhesion with an acrylic shell or primer, has low resin cost, is economical, and does not cause cracks or peeling. An object of the present invention is to provide a resin composition for reinforcing an acrylic resin molded product that can be molded in a short cycle (high cycle).

The reason why the adhesion between the acrylic shell and the unsaturated polyester resin is low is that there is a large difference in polarity between the two. If the composition of the unsaturated polyester resin itself is changed, the adhesiveness with the acrylic shell can be improved to some extent, but it is difficult to solve the above-mentioned problems only by this. In particular, when the curing speed is increased in order to improve productivity, a larger shrinkage stress is generated. Therefore, it is essential to develop an adhesion force that overcomes the shrinkage stress from the initial stage of curing.
Therefore, the present inventors paid attention to a resol type phenol resin having a methylol group which is a polar group in the molecule, and as a result of earnestly examining the combination of the resol type phenol resin and the unsaturated polyester resin, the unsaturated polyester resin was obtained. By using a resin composition obtained by adding 0.2 to 5 parts by mass of a resol type phenolic resin to 100 parts by mass as a reinforcing layer of an acrylic resin molded product, adhesion with an acrylic shell or primer is remarkably improved, and peeling is performed. The inventors have found that molding can be performed in a short cycle without occurrence, and the present invention has been completed.

That is, the present invention provides a reinforcing layer formed on the surface of an acrylic resin molded article , which contains 0.2 to 5 parts by mass of a resol type phenolic resin with respect to 100 parts by mass of an unsaturated polyester resin. It is a resin composition.
It is preferable that the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article further contains 40 to 100 parts by mass of vinyl ester resin with respect to 100 parts by mass of the unsaturated polyester resin.
Furthermore, the vinyl ester resin is preferably a bisphenol type vinyl ester resin.
The unsaturated polyester resin is preferably composed of an isophthalic acid unsaturated polyester resin, a terephthalic acid unsaturated polyester resin, or a mixture thereof.
The unsaturated polyester resin is also preferably composed of an isophthalic acid unsaturated polyester resin, a terephthalic acid unsaturated polyester resin or a mixture thereof, and a dicyclopentadiene-modified unsaturated polyester resin.
Further, the present invention is that the reinforcing layer made of pre Bark fat composition is an acrylic resin product characterized by comprising forming on the surface of the acrylic resin molded article.

According to the present invention, it is formed on the surface of an acrylic resin molded product that has excellent adhesion to an acrylic shell or primer, has low resin cost, is economical, and can be molded in a short cycle without causing cracks or peeling. A resin composition for the reinforcing layer can be provided.

The resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article according to the present invention is 0.2 to 5 parts by mass, preferably 0, of resol type phenolic resin with respect to 100 parts by mass of the unsaturated polyester resin. 4 to 2 parts by mass are contained. When the resol type phenolic resin is less than 0.2 part by mass relative to 100 parts by mass of the unsaturated polyester resin, the adhesion with the acrylic shell is insufficient, and when it exceeds 5 parts by mass, the curability and hardness developability are increased. descend.

(Unsaturated polyester resin)
As the unsaturated polyester resin in the present invention, an esterification reaction between a polyhydric alcohol and an unsaturated polybasic acid and / or an acid anhydride thereof (and a saturated polybasic acid and / or an acid anhydride as required). Any conventionally known product obtained by dissolving the resulting condensation product (unsaturated polyester) in a polymerizable monomer can be used without limitation. Here, when using a saturated polybasic acid and / or acid anhydride thereof as a raw material, the total amount of the unsaturated polybasic acid and / or acid anhydride thereof from the viewpoint of improving the heat resistance and water resistance of the reinforcing layer. Is preferably 50 mol% or more of the total acid component. Such known unsaturated polyester resins are described in, for example, “Polyester Resin Handbook” (Nikkan Kogyo Shimbun, published in 1988) and “Paint Glossary of Terms” (edited by Color Material Association, published in 1993). .
Further, it can be obtained by adding dicyclopentadiene during esterification reaction of polyhydric alcohol with unsaturated polybasic acid and / or acid anhydride thereof (saturated polybasic acid and / or acid anhydride if necessary). A dicyclopentadiene-modified unsaturated polyester resin can also be used.

Here, examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2- Examples include methyl-1,3-propanediol, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct.
Examples of the unsaturated polybasic acid and its acid anhydride include maleic acid, fumaric acid, itaconic acid, maleic anhydride and the like.
Examples of the saturated polybasic acid and its acid anhydride include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, trimellitic acid, trimellitic anhydride, adipic acid, and sebacic acid.
Examples of the polymerizable monomer include styrene, vinyl toluene, chlorostyrene, dichlorostyrene, α-methylstyrene, tert-butylstyrene, divinylbenzene, methyl methacrylate, methyl acrylate, ethyl acrylate, vinyl acetate, and phthalic acid. Although diallyl etc. are mentioned, Styrene is preferable.

  Among the unsaturated polyester resins obtained from the above raw materials, isophthalic acid-based unsaturated polyester resins, terephthalic acid-based unsaturated polyester resins, or mixtures thereof are preferable from the viewpoint of further improving the heat resistance and water resistance of the reinforcing layer.

  In addition, by blending dicyclopentadiene-modified unsaturated polyester resin with isophthalic acid-based unsaturated polyester resin, terephthalic acid-based unsaturated polyester resin, or a mixture thereof, the viscosity of the resin composition is reduced, and workability, in particular, The injection property of the resin compound in the RTM molding can be improved. When dicyclopentadiene-modified unsaturated polyester resin is used in combination, isophthalic acid-based unsaturated polyester resin, terephthalic acid-based unsaturated polyester resin or a mixture thereof is 40 to 80% by mass, dicyclopentadiene-modified unsaturated polyester resin 20 to 60% by mass. When the dicyclopentadiene-modified unsaturated polyester resin is less than 20% by mass, the effect of reducing the viscosity is low, which is not preferable. Moreover, when it exceeds 60 mass%, since adhesiveness with an acrylic shell and the impact strength of a reinforcement layer fall, it is unpreferable.

(Resol type phenol resin)
In the present invention, the resol type phenolic resin has an effect of improving the adhesion to the acrylic shell and does not adversely affect the adhesion to the primer layer applied on the acrylic shell.
The resol-type phenol resin in the present invention is a compound obtained by reacting phenols and aldehydes in an equimolar ratio or in excess of aldehydes in the presence of a basic catalyst, and a methylol group or dimethylol is present in the molecule. It has a group. The production method is not particularly limited, and is usually obtained by reacting 1 to 5 mol of aldehyde with 1 mol of phenol at 40 to 100 ° C. for 1 to 7 hours in the presence of a basic catalyst. it can.

Here, the phenols may include all those having one or more phenolic hydroxyl groups in the molecule. More specifically, phenol, cresol, xylenol, tert-butylphenol, phenylphenol, nonylphenol, cumylphenol, isopropenylphenol, bromophenol, fluorophenol, aminophenol, resorcinol, catechol, isopropylcatechol, pyrogallol, glycinol, bisphenol A, bisphenol F, bisphenol S, biphenol, naphthol, etc. are mentioned, These can be used individually or in combination of 2 or more types.
Examples of aldehydes include, but are not limited to, formalin, paraformaldehyde, trioxane, tetraoxane, acetal, glyoxal, acetaldehyde, butyraldehyde, benzaldehyde, acrolein, furfural and the like.
Examples of the basic catalyst include alkaline chemical species such as sodium hydroxide, sodium carbonate, alkaline earth metal oxides and hydroxides, ammonia, and hexamine.

  Among the resol-type phenolic resins obtained from the above raw materials, it improves adhesion to the acrylic shell and does not cause polymerization inhibition when added to an unsaturated polyester resin or a mixture of an unsaturated polyester resin and a vinyl ester resin. Therefore, the total amount of monomer to trimer of phenols having two or more methylol groups in one molecule is 80% by mass or more, and unreacted phenol monomers and phenol monomethylolated products And the total amount of the tetramer or higher component of phenols is preferably less than 20% by mass.

(Vinyl ester resin)
Moreover, the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article according to the present invention may further contain 40 to 100 parts by mass of vinyl ester resin with respect to 100 parts by mass of unsaturated polyester resin. Good. In particular, when a dicyclopentadiene-modified unsaturated polyester resin is used as the unsaturated polyester resin, the adhesion between the acrylic shell and the reinforcing layer can be further improved by adding a vinyl ester resin to the resin composition.
The vinyl ester resin in the present invention is sometimes referred to as an epoxy acrylate resin, and a compound having a polymerizable unsaturated bond (vinyl ester) obtained by an esterification reaction of an epoxy compound and acrylic acid or methacrylic acid is used as a polymerizable monomer. Conventionally known products obtained by dissolving in can be used without limitation. Such known vinyl ester resins are described in, for example, “Polyester Resin Handbook” (published by Nikkan Kogyo Shimbun, 1988) and “Paint Glossary of Terms” (edited by Color Material Association, published in 1993).

Here, examples of the epoxy compound include bisphenol type glycidyl ether and novolac type glycidyl ether. More specifically, as a raw material for vinyl ester resin, a reaction product of bisphenol A and epichlorohydrin, a reaction product of hydrogenated bisphenol A and epichlorohydrin, a reaction product of cyclohexanedimethanol and epichlorohydrin, a norbornane dialcohol and epichlorohydrin Reaction product, reaction product of tetrabromobisphenol A and epichlorohydrin, reaction product of tricyclodecane dimethanol and epichlorohydrin, alicyclic diepoxy carbonate, alicyclic diepoxy acetal, alicyclic diepoxycarboxylate, novolak type Examples thereof include glycidyl ether and cresol novolac glycidyl ether.
As a polymerizable monomer, the thing similar to what was used by unsaturated polyester resin can be used.
In addition, as the vinyl ester resin in the present invention, a terminal carboxyl group-saturated polyester or unsaturated polyester obtained from a saturated dicarboxylic acid and / or an unsaturated dicarboxylic acid and a polyhydric alcohol without using the above epoxy compound as a raw material. A saturated polyester obtained by reacting an α, β-unsaturated carboxylic acid ester having an epoxy group or a polyester (meth) acrylate of an unsaturated polyester can also be used.

  Examples of the saturated dicarboxylic acid include dicarboxylic acids having no active unsaturated group, such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, adipic acid, and sebacic acid. Examples of the unsaturated dicarboxylic acid include dicarboxylic acids having an active unsaturated group, such as fumaric acid, maleic acid, maleic anhydride, and itaconic acid. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl- Examples include 1,3-propanediol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A.

  Among the vinyl ester resins obtained from the above raw materials, bisphenol type vinyl ester resins are preferred from the viewpoint of preventing cracks when the reinforcing layer is cured.

In addition, the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article of the present invention does not refuse the addition of known additives, and depending on the intended use, a curing accelerator and a curing acceleration aid. An agent, a thermoplastic polymer component, an antifoaming agent, a dispersant, an impregnating agent, a pigment, an internal mold release agent and the like may be added.
Examples of the curing agent (organic peroxide) include ketone peroxides, diacyl peroxides, hydroperoxides, diallyl peroxides, peroxyketals, alkyl peresters, and carbonates.
As a hardening accelerator, well-known metal soaps, such as cobalt naphthenate and cobalt octenoate, are mentioned.
As the curing accelerating aid, known amines and the like are used. More specifically, dimethylaniline, diethylaniline, dimethylparatoluidine, triethanolamine, acetylacetone and the like can be mentioned.

  The resole-type phenol resin has a structure similar to a polymerization inhibitor typified by hydroquinone, and tends to delay room temperature curing. An effective curing system to offset this delay effect and increase the curing rate at room temperature is a combination of ketone peroxides acetylacetone peroxide, cobalt naphthenate and dimethylparatoluidine. Further, when a small amount of a medium temperature decomposition type organic peroxide (such as an alkyl perester) is used in combination as a curing agent, adhesion strength at the initial stage of curing can be further expressed.

In addition, the shape and design of acrylic resin bathtubs are becoming more and more complex year by year, and the shape of the curved surface portion is becoming sharper. When the shape of the acrylic shell becomes complicated, the preform glass cannot follow the shape of the acrylic shell, and there is almost no glass fiber, and a resin-only portion (resin rich portion) tends to occur.
The resin-rich portion is liable to crack when cured, particularly when the curing rate is high. In such a case, a thermoplastic polymer component may be added to the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article of the present invention. Examples of the thermoplastic polymer component include polystyrene, polyvinyl acetate, styrene / vinyl acetate copolymer, styrene / olefin copolymer, and the like.

The resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article of the present invention can be prepared by mixing each of the above components at a desired ratio. The method of mixing each component is arbitrary, For example, it can carry out by preparing each component in a stainless steel container at room temperature of 25 ° C. and stirring for 60 minutes with a stirrer. The resol type phenol resin is solid (powder), but is dissolved in the resin by the above operation. The order of mixing the components is also arbitrary.

Next, the performance and properties required for the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded product will be described below. In terms of workability and productivity in the resin injection manufacturing process such as RTM that forms a reinforcing layer on acrylic molded products, the resin requires low viscosity, fast curability, good for reinforcing fibers such as glass fiber Such as good impregnation.
From the viewpoint of cost and strength improvement of the reinforcing layer, it is preferable to add 20 to 70 parts by mass of a filler such as calcium carbonate, aluminum hydroxide or magnesium silicate with respect to 100 parts by mass of the resin composition. Therefore, it is desirable to design the viscosity of the resin composition before adding the filler to 300 mPa · s / 25 ° C. or less. Thereby, for example, the viscosity of the resin composition (resin compound) to which 60 parts of calcium carbonate is added is about 1000 mPa · s, and the acrylic bathtub reinforcing layer molding of 1600 mm size (large bathtub for private houses) is performed by RTM molding. In this case, the time required to inject about 30 kg of resin compound into the RTM mold is about 5 minutes, which can contribute to high cycle productivity.
The curability of the resin compound is preferably such that the gelation time is 7 to 9 minutes and the time to reach the maximum exothermic temperature (curing time) is 10 to 13 minutes. If it has such a fast curing property, it can be removed from the RTM mold without gelation during the injection for about 5 minutes, and about 20 minutes after the injection is completed. It can be completed in about 30 minutes.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, these are merely examples and do not limit the present invention.

Each resin used for the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article was prepared according to Synthesis Examples 1 to 4 below.

(Synthesis Example 2)
A reactor equipped with a stirrer, a fractionation condenser, a gas introduction tube and a thermometer was charged with 110 mol of dicyclopentadiene, 110 mol of water and 105 mol of maleic anhydride, and reacted at 130 ° C. for 2 hours. Got the rate. Further, 65 mol of propylene glycol was added to conduct esterification reaction, and when the acid value reached 15 mgKOH / g, the reaction was terminated to obtain dicyclopentadiene-modified unsaturated polyester. 60 parts by mass of this dicyclopentadiene-modified unsaturated polyester was dissolved in 40 parts by mass of styrene to which 0.01 part by mass of hydroquinone was added to obtain a dicyclopentadiene-modified unsaturated polyester resin (UP-2).

(Synthesis Example 3)
In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas introduction tube, and a thermometer, 189 parts by mass of Epicoat 828 (manufactured by Yuka Shell Co., Ltd., epoxy resin; epoxy equivalent 189), 23 parts by mass of bisphenol A, triethylamine 0 .32 parts by mass was charged and reacted at 150 ° C. for 2 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled to 90 ° C, charged with 69 parts by weight of methacrylic acid, 0.3 parts by weight of tris (dimethylamino) phenol and 0.08 parts by weight of methylhydroquinone, and reacted at 125 ° C for 5 hours while blowing air. The reaction was terminated when the acid value reached 12 mgKOH / g, and a bisphenol type vinyl ester was obtained. 60 parts by mass of this bisphenol type vinyl ester was dissolved in 40 parts by mass of styrene added with 0.02 part by mass of hydroquinone to obtain a bisphenol type vinyl ester resin (VE-1).

(Synthesis Example 4)
To a reaction apparatus equipped with a stirrer, a reflux condenser, a gas introduction pipe and a thermometer, 500 parts by mass of phenol, 1750 parts by mass of 37% formalin and 15 parts by mass of calcium hydroxide are added, and the temperature is gradually raised. Reacted for hours. Next, the mixture was cooled to near room temperature, and the calcium sulfate produced after adjusting to pH 7 with sulfuric acid was filtered, and the water was removed under reduced pressure to obtain 863 parts by mass of a resol type phenolic resin (PH-1). .
When analyzed by GPC using tetrahydrofuran as a solvent, the total content of polycondensates of phenol monomer, monomethylolphenol, tetramer or higher phenol and formaldehyde was 8% by mass.

(Example 1)
100 parts by mass of UP-1 obtained in Synthesis Example 1 and 0.8 part by mass of PH-1 obtained in Synthesis Example 4 were blended, and 0.6% of 6% cobalt naphthenate was added to the resin mixture as a curing accelerator. 0.7 parts by mass of dimethyl paratoluidine as a curing accelerator, 0.03 parts by mass of tert-butylcatechol for adjusting the curing time, and BYK-A515 (manufactured by Big Chemie Japan KK) as an antifoaming agent The reinforcing resin composition of Example 1 was obtained by blending 0.15 parts by mass. 20 parts by mass of calcium carbonate (manufactured by Nitto Flour Chemical Co., Ltd., NS100) was mixed with 100 parts by mass of this reinforcing resin composition to obtain a resin compound. The viscosity of the resin compound was 1150 mPa · s that can be injected by an RTM molding machine.

The resin compound was injected with an RTM injection machine into an RTM mold of 25 to 30 ° C. in which an acrylic shell having a length of 1600 mm and a preform not set on the surface and a preform were set. The curing agent acetylacetone peroxide (Trigonox 40 manufactured by Kayaku Akzo KK) was mixed with the resin compound at the tip of the injector (immediately before being injected into the RTM mold). The addition amount of the curing agent was 1.2 parts by mass.
When 50 shots (about 30 kg) were injected with an RTM injection machine, the resin compound overflowed from the mold, and the injection was completed. The infusion took 5.1 minutes. After completion of the injection, the resin compound gelled in about 3 minutes and reached the maximum exothermic temperature in about 9 minutes. Thereafter, it was naturally cooled and removed from the RTM mold 20 minutes after the completion of the injection to obtain an acrylic resin bathtub. The obtained acrylic resin bathtub had good appearance on both the acrylic shell side (front side) and the reinforcing layer side (back side). The barcol hardness on the reinforcing layer side reached 30 to 35 after 30 minutes from demolding.
When the end of this acrylic resin bath was cut (trimmed) with a cutting machine and the cross section was observed, the acrylic shell and the reinforcing layer were sufficiently adhered, and no peeling was observed.
Similarly, an acrylic resin bath was obtained by injecting RTM into an acrylic shell having a vinyl ester resin coated on its surface as a primer. The obtained acrylic resin bathtub had good appearance on both the acrylic shell side (front side) and the reinforcing layer side (back side), and no peeling was observed on the trimming section.
When the obtained two acrylic resin bathtubs (with primer and without primer) were subjected to an 80 ° C. continuous hot water resistance test for 1000 hours, neither of the bathtubs was swollen or whitened.

(Example 2)
30 parts by mass of UP-1 obtained in Synthesis Example 1, 30 parts by mass of UP-2 obtained in Synthesis Example 2, 40 parts by mass of VE-1 obtained in Synthesis Example 3 and PH- obtained in Synthesis Example 4 0.6 parts by mass of 1 and 0.7 parts by mass of 6% cobalt naphthenate as a curing accelerator and 0.8 parts by mass of dimethylparatoluidine as a curing accelerator were added to the resin mixture. Therefore, 0.02 parts by mass of tert-butylcatechol and 0.15 parts by mass of BYK-A515 (manufactured by Big Chemie Japan Co., Ltd.) as an antifoaming agent were blended to obtain a reinforcing resin composition of Example 2. . 60 parts by mass of calcium carbonate (manufactured by Nitto Flour Chemical Co., Ltd., NS100) was mixed with 100 parts by mass of this reinforcing resin composition to obtain a resin compound. The viscosity of the resin compound was 920 mPa · s (25 ° C.) that can be injected by an RTM molding machine.

In the same manner as in Example 1, two acrylic resin baths were RTM molded. The injection took 4.5 minutes. After completion of the injection, the resin compound gelled in about 3 minutes and reached the maximum exothermic temperature in about 10 minutes. Thereafter, it was naturally cooled and removed from the RTM mold 20 minutes after the completion of the injection to obtain an acrylic resin bathtub. The barcol hardness on the reinforcing layer side reached 35-40 after 30 minutes from demolding.
The two acrylic resin baths obtained had good appearance on the acrylic shell side (front side) and the reinforcing layer side (back side), and no peeling was observed on the trimming section.
In addition, when two acrylic resin bathtubs were subjected to an 80 ° C. continuous hot water resistance test for 1000 hours, none of the bathtubs were swollen or whitened.

Example 3
20 parts by mass of UP-1 obtained in Synthesis Example 1, 30 parts by mass of UP-2 obtained in Synthesis Example 2, 50 parts by mass of VE-1 obtained in Synthesis Example 3, and PH- obtained in Synthesis Example 4 1.0 parts by mass of 1 and 0.8 parts by mass of 6% cobalt naphthenate as a curing accelerator, 0.8 parts by mass of dimethyl paratoluidine as a curing accelerator, and curing time For adjustment, 0.01 parts by mass of tert-butylcatechol and 0.15 parts by mass of BYK-A515 (manufactured by Big Chemie Japan KK) as an antifoaming agent were blended to obtain a resin composition. A resin compound was prepared by mixing 70 parts by mass of calcium carbonate (NS100 manufactured by Nitto Flour Chemical Co., Ltd.) with 100 parts by mass of the resin composition. The viscosity of the resin compound was 970 mPa · s (25 ° C.) that can be injected by an RTM molding machine.

In the same manner as in Example 1, two acrylic bathtubs were RTM molded. The addition amount of the curing agent (Trigonox 40) was 1.5 parts by mass. The injection took 4.5 minutes. After completion of the injection, the resin compound gelled in about 5 minutes and reached the maximum exothermic temperature in about 12 minutes. Thereafter, it was naturally cooled, and was removed from the RTM mold 20 minutes after the completion of the injection to obtain an acrylic bathtub. The barcol hardness on the reinforcing layer side reached 30 to 35 after 30 minutes from demolding.
The two acrylic resin baths obtained had good appearance on the acrylic shell side (front side) and the reinforcing layer side (back side), and no peeling was observed on the trimming section.
In addition, when two acrylic resin bathtubs were subjected to an 80 ° C. continuous hot water resistance test for 1000 hours, none of the bathtubs were swollen or whitened.

Example 4
70 parts by mass of UP-1 obtained in Synthesis Example 1, 30 parts by mass of VE-1 obtained in Synthesis Example 3, 0.4 parts by mass of PH-1 obtained in Synthesis Example 4 were further blended, and this resin mixture 0.5 parts by mass of 6% cobalt naphthenate as a curing accelerator, 0.6 parts by mass of dimethyl paratoluidine as a curing accelerator, 0.03 parts by mass of tert-butylcatechol for adjusting the curing time As a defoaming agent, 0.15 parts by mass of BYK-A515 (manufactured by Big Chemie Japan KK) was blended to obtain a resin composition. 40 parts by mass of calcium carbonate (NS100 manufactured by Nitto Flour Industry Co., Ltd.) was mixed with 100 parts by mass of this resin composition to obtain a resin compound. The viscosity of the resin compound was 1100 mPa · s (25 ° C.) that can be injected by an RTM molding machine.

In the same manner as in Example 1, two acrylic bathtubs were RTM molded. The addition amount of the curing agent was 1.0 part by mass. The infusion took 5.2 minutes. After completion of the injection, the resin compound gelled in about 4 minutes and reached the maximum exothermic temperature in about 11 minutes. Thereafter, it was naturally cooled, and was removed from the RTM mold 20 minutes after the completion of the injection to obtain an acrylic bathtub. The barcol hardness on the reinforcing layer side reached 30 to 35 after 30 minutes from demolding.
The two acrylic resin baths obtained had good appearance on the acrylic shell side (front side) and the reinforcing layer side (back side), and no peeling was observed on the trimming section.
In addition, when two acrylic resin bathtubs were subjected to an 80 ° C. continuous hot water resistance test for 1000 hours, none of the bathtubs were swollen or whitened.

(Comparative Example 1)
30 parts by mass of UP-1 obtained in Synthesis Example 1, 30 parts by mass of UP-2 obtained in Synthesis Example 2 and 40 parts by mass of VE-1 obtained in Synthesis Example 3 were further blended, and this resin mixture was cured. 0.3 parts by mass of 6% cobalt naphthenate as an accelerator, 0.1 parts by mass of dimethylparatoluidine as an accelerator for curing, 0.007 parts by mass of tert-butylcatechol for adjusting the curing time, an antifoaming agent As a result, 0.15 parts by mass of BYK-A515 (manufactured by Big Chemie Japan Co., Ltd.) was blended to obtain a reinforcing resin composition of Comparative Example 1. This reinforcing resin composition is obtained by adjusting curability after removing the resol type phenol resin (PH-1) from Example 2. A resin compound was prepared by mixing 60 parts by mass of calcium carbonate (manufactured by Nitto Flour Chemical Co., Ltd., NS100) with 100 parts by mass of this resin composition.
In the same manner as in Example 1, two acrylic resin baths were RTM molded. When the two acrylic resin bathtubs were trimmed and the cross section was observed, the acrylic shell and the reinforcing layer were in close contact with each other, and no peeling was observed. On the other hand, for the acrylic shell to which the primer was not applied, peeling was observed on a part of the trimming surface.
When the 80 ° C continuous hot water resistance test was carried out for the two acrylic resin baths obtained (with primer and without primer), the acrylic resin bath with primer was subjected to the 80 ° C continuous hot water test after 1000 hours. No blistering or whitening occurred. On the other hand, the tub without primer had several bulges at 200 hours.

(Comparative Example 2)
100 parts by mass of a liquid acrylic resin (made by Nippon Lucas Co., Ltd., Modal M972), 0.2 parts by mass of dimethylparatoluidine as a curing accelerator, and 0.5 parts by mass of Floren AC-326F (manufactured by Kyoeisha Chemical Co., Ltd.) as an antifoaming agent 0.4 parts by mass of BYK-9010 (manufactured by Big Chemie Japan KK) as a part and a dispersant were blended to obtain a reinforcing resin composition of Comparative Example 2. This reinforcing resin mixture was mixed with 70 parts by mass of calcium carbonate (NS100 manufactured by Nitto Flour Industries) to obtain a resin compound. The viscosity of the resin compound was 940 mPa · s, which was a level that could be injected by an RTM molding machine.

1.2 parts by mass of a benzoyl peroxide derivative (NIPPER BTM-M, manufactured by NOF Corporation) as a curing agent is mixed at the tip of the RTM injector, and two acrylic resin bathtubs are formed in the same manner as in Example 1. Obtained. The injection took 5.0 minutes. After completion of the injection, the resin compound gelled in about 5 minutes and reached the maximum exothermic temperature in about 10 minutes. Thereafter, it was naturally cooled and removed from the RTM mold 20 minutes after the completion of the injection to obtain an acrylic resin bathtub. The obtained acrylic resin bathtub had good appearance on both the acrylic shell side (front side) and the reinforcing layer side (back side). The barcol hardness on the reinforcing layer side reached 35 to 45 after 30 minutes from demolding.
When the 80 ° C continuous hot water resistance test was conducted on the two acrylic resin baths obtained (with primer and without primer), the acrylic resin bath with primer had a diameter of about 5 mm at the corner at 800 hours. Several blisters occurred. On the other hand, the tub without primer did not swell or whiten after 1000 hours of continuous 80 ° C. hot water resistance test.

As is clear from the above results, the acrylic resin bath reinforced with the resin composition for the reinforcing layer formed on the surface of the acrylic resin molded article obtained in Examples 1 to 4 is injected, cured and Even if the cycle of demolding is performed in less than 30 minutes, cracks and peeling do not occur in the reinforcing layer at the initial stage of curing, and sufficient adhesion strength is expressed at the initial stage of curing. Furthermore, even after a hot water resistance test at 80 ° C. for 1000 hours, swelling and whitening do not occur, and thus the adhesion strength after contact with warm water over a long period of time is excellent. In addition, the resin compositions obtained in Examples 1 to 4 have a low resin cost and are very excellent in economic efficiency as compared with the acrylic resin as in Comparative Example 2.

Claims (6)

A resin composition for a reinforcing layer formed on the surface of an acrylic resin molded article , comprising 0.2 to 5 parts by mass of a resol type phenolic resin with respect to 100 parts by mass of an unsaturated polyester resin. 2. The reinforcing layer formed on the surface of the acrylic resin molded product according to claim 1, further comprising 40 to 100 parts by mass of a vinyl ester resin with respect to 100 parts by mass of the unsaturated polyester resin . Resin composition. The resin composition for a reinforcing layer formed on the surface of an acrylic resin molded article according to claim 2, wherein the vinyl ester resin is a bisphenol type vinyl ester resin. The said unsaturated polyester resin consists of an isophthalic acid type unsaturated polyester resin, a terephthalic acid type unsaturated polyester resin, or these mixtures, The acrylic resin molded article as described in any one of Claims 1-3 characterized by the above-mentioned. The resin composition for the reinforcement layer formed in the surface of this. The said unsaturated polyester resin consists of an isophthalic acid type unsaturated polyester resin, a terephthalic acid type unsaturated polyester resin, or a mixture thereof, and a dicyclopentadiene modified unsaturated polyester resin. The resin composition for the reinforcement layer formed in the surface of the acrylic resin molding as described in any one. Acrylic resin product characterized in that a reinforcing layer made of tree fat composition according to any one of claims 1 to 5 obtained by forming on the surface of the acrylic resin molded article.