JP2003292647A - Sheet molding compound and method for producing molded article of sheet molding compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a molded article of a sheet molding compound (SMC) capable of obtaining the SMC molded article which excels in heat insulating properties, and additionally is rendered lightweight in one step, and the SMC therefor. <P>SOLUTION: The sheet molding compound is obtained by impregnating a foam in the form of a sheet with a saturated polyester composition comprising an unsaturated polyester resin, a polymerizable monomer, a shrinkage reducing agent, a curing agent, and a thickening agent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet molding compound (hereinafter referred to as SMC) which is a molding material used for bathroom wall panels, bathroom equipment such as floor pans, panel assembly type water storage tanks, etc., and its SMC. SM to use
The present invention relates to a method for manufacturing a C molded product.

[0002]

2. Description of the Related Art SMC is an unsaturated polyester diluted with a vinyl monomer, and has additives such as a low-shrinking agent, a curing agent, a polymerization inhibitor, a filler, a thickener, a release agent, and coloring. It is a molding material obtained by impregnating glass fiber into a paste mixed with an agent or the like to form a sheet, covering both sides with a carrier film, aging and semi-solidifying. This SMC is placed on a mold and pressure-heat molded, and is manufactured as an SMC molded product such as a bath, a panel assembly type water storage tank, and a septic tank.

[0003]

The SMC molded article which has been pressure-heat molded as described above has excellent durability, water resistance, mechanical strength, gloss of the surface of the molded article, and the degree of freedom of shape. It is widely used as bathroom equipment such as bathtubs, panel assembly type water storage tanks, septic tanks, etc. because of its large size and excellent design. However, the above-mentioned SMC molded product is a rigid molded product having unsaturated polyester resin, inorganic filler such as calcium carbonate / aluminum hydroxide and glass fiber as main components and a specific gravity of 1.6 to 1.9. , Insulation performance is not sufficient, especially when used in cold regions,
In order to improve the heat retention performance by spraying a urethane foam or a polystyrene foam on the back surface of the molded product, it is necessary to impart heat insulation.

The present invention has been made in view of the above problems, and provides a method for producing an SMC molded product which can obtain an SMC molded product which is excellent in heat insulation properties and can be reduced in weight in one step, and an SMC therefor. The purpose is to do.

[0005]

The present invention relates to the following. 1. A sheet molding compound obtained by impregnating a sheet-like foam with an unsaturated polyester composition containing an unsaturated polyester resin, a polymerizable monomer, a low-shrinking agent, a curing agent and a thickener. 2. Item 2. The sheet molding compound according to item 1, wherein glass fibers are arranged on one side or both sides of a sheet-shaped foam. 3. A method for producing a sheet molding compound molded article, comprising arranging a sheet molding compound containing a glass fiber on both sides or one side of the sheet molding compound according to Item 1 or 2 and performing thermocompression molding.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The unsaturated polyester resin composition of the present invention comprises an unsaturated polyester resin, a polymerizable monomer, a low-shrinking agent, a curing agent and a thickening agent.

The unsaturated polyester resin in the present invention is obtained by reacting a polybasic acid component containing α, β-unsaturated polybasic acid or its anhydride as an essential component with a polyhydric alcohol. In the present invention, as the α, β-unsaturated polybasic acid or its anhydride, which is a synthetic raw material of the unsaturated polyester resin, for example, α, β-unsaturated dibasic acid or its anhydride, for example, maleic acid, Examples thereof include fumaric acid, itaconic acid, citraconic acid, maleic anhydride, and their anhydrides. You may use 2 or more types together. Examples of the polybasic acid component include α, β-unsaturated polybasic acids or their anhydrides as well as saturated polybasic acids in order to adjust the concentration of unsaturated groups, and impart properties such as flexibility and heat resistance. It is preferable to use a basic acid or its anhydride together. At this time, α, β-
The unsaturated polybasic acid or its anhydride is preferably 40 mol% or more of the polybasic acid component. α, β-
When the unsaturated polybasic acid or its anhydride is less than 40 mol%, the strength of the obtained molded article tends to gradually decrease. From this, it is more preferable that the α, β-unsaturated polybasic acid or its anhydride is 45 to 80 mol%.
It is particularly preferably from 0 to 70 mol%.

Examples of the saturated polybasic acid or its anhydride used in combination include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, Hexahydrophthalic acid, hexahydrophthalic anhydride, glutaric acid, adipic acid, sebacic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, dimer acid, succinic acid, azelaic acid, rosin-maleic acid adduct, etc. To be These may be used in combination of two or more.

As the polyhydric alcohol which is another raw material for synthesizing the unsaturated polyester resin, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,
6-hexanediol, neopentyl glycol, 1,
Examples thereof include dihydric alcohols such as 4-cyclohexanediol and hydrogenated bisphenol A, trihydric alcohols such as glycerin and trimethylolpropane, and tetrahydric alcohols such as pentaerythritol. These may be used in combination of two or more.

The polybasic acid component and the polyhydric alcohol are preferably used in an equivalent ratio of 1 to 1.3 when the polybasic acid component is 1.
It is more preferable to use in the range of 1.05. When the amount of polyhydric alcohol is small, the molecular weight of the unsaturated polyester resin obtained tends to be small, and when it is large, the acid value is small and the progress of thickening by the thickener tends to be slow.

The unsaturated polyester resin can be produced by a conventionally known method. For example,
Condensation reaction of polybasic acid component and polyhydric alcohol component,
The process proceeds while removing the condensation water generated when both components react with each other. Removal of the condensed water to the outside of the system is preferably carried out by natural distillation or reduced pressure distillation by passing an inert gas. A solvent such as toluene or xylene can be added to the system as an azeotropic component in order to accelerate the distillation of the condensed water. The progress of the reaction can be generally known by measuring the amount of distillate produced by the reaction, quantifying the terminal functional group, measuring the viscosity of the reaction system, and the like. The reaction temperature is preferably 150 ° C. or higher, and the reaction is preferably carried out while aerating an inert gas such as nitrogen or carbon dioxide to prevent side reactions due to oxidation. From this, as the reaction apparatus, those made of glass, stainless steel or the like are selected, and the stirring apparatus, the fractionation apparatus for preventing the distillation of the alcohol component due to the azeotropic distillation of water and the alcohol component, and the temperature of the reaction system are increased. It is preferable to use a reaction device equipped with a heating device, a temperature control device for this heating device, and a device for blowing in an inert gas such as nitrogen.

The unsaturated polyester has a number average molecular weight of 25.
It is preferably from 00 to 4500. Molecular weight is 250
When it is lower than 0, the viscosity does not increase even if an appropriate amount of the thickener is added, and when it is made into a resin composition, it is soft and the workability is deteriorated. When the molecular weight is larger than 4,500, the viscosity is high and impregnation of the glass fiber is caused to cause poor surface gloss when molded.

Examples of the polymerizable monomer used in the present invention include styrene, chlorostyrene, divinylbenzene, tert-butylstyrene, styrene derivatives such as styrene bromide, methyl methacrylate, ethyl methacrylate, ethyl acrylate. , Methacrylic acid such as butyl acrylate or alkyl ester of acrylic acid, β-hydroxyethyl methacrylate, methacrylic acid such as ethyl β-hydroxyacrylate or hydroxyalkyl ester of acrylic acid, diallyl phthalate, acrylamide, phenylmaleimide, etc. To be Also, polyfunctional methacrylic acid or acrylic acid esters such as ethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and trimethylol propane trimethacrylate can be used.

An unsaturated polyester resin composition is prepared by blending an unsaturated polyester resin and a polymerizable monomer, and optionally adding a polymerization inhibitor and the like. The mixing ratio of the unsaturated polyester resin and the polymerizable monomer at this time is 25 to 80 parts by weight of the unsaturated polyester resin and 75 to 100 parts by weight of the polymerizable monomer when the total amount of the two is 100 parts by weight. It is preferably 20 parts by weight. When the amount is less than 25 parts by weight, the viscosity of the unsaturated polyester resin composition is too low to be applied in a sheet form, and it is difficult to uniformly mix with other components due to sedimentation and the like. Even when the material is molded, the curing shrinkage rate is large and the molded product may be cracked or cracked. 80 unsaturated polyester resin
If the amount is more than parts by weight, the viscosity may be too high and it may be difficult to apply or mix with other components. From this, it is more preferable that the unsaturated polyester resin is 40 to 65 parts by weight and the polymerizable monomer is 60 to 35 parts by weight. Examples of the polymerization inhibitor include p-benzoquinone, naphthoquinone, toluquinone, hydroquinone, mono-t-butylhydroquinone, dibutylhydroxytoluene and the like. The polymerization inhibitor is preferably used in an amount of 0.5% by weight or less based on the total amount of the unsaturated polyester resin and the polymerizable monomer. When the curing agent is blended, it is preferably contained in an amount of 0.05% by weight or more for storage stability.

As the low-shrinkage agent used in the present invention, thermoplastic resins such as polymethylmethacrylate, polystyrene, polycaprolactone, polyvinyl acetate, polyethylene and butadiene rubber are used. The amount used is determined in consideration of the shrinkage rate, surface smoothness, and surface gloss of the molded product, and is not particularly limited. The low-shrinking agent is preferably used in the range of 20 to 50% by weight based on the total amount of the unsaturated polyester resin and the polymerizable monomer.

As the curing agent used in the present invention, ketone peroxides, peroxydicarbonates, hydroperoxides, diacyl peroxides,
Peroxyketals, dialkyl peroxides,
Examples thereof include peroxyesters and alkyl peresters. The amount of the curing agent affects not only the molding cycle but also the storability of the material, color unevenness, and the like, and thus is determined depending on each. From the standpoint of the storability of the material and the molding cycle, it is preferably 0.5 to 5% by weight, more preferably 1 to 3% by weight, based on the total amount of the unsaturated polyester resin and the polymerizable monomer.

Magnesium oxide, magnesium hydroxide, potassium oxide, potassium hydroxide and the like are used as the thickener, but magnesium oxide is generally used. The amount of the thickener is determined according to the workability of the molding material, but is preferably 0.5 to 5% by weight, and more preferably the total amount of the unsaturated polyester resin and the polymerizable monomer. It is 0.7 to 2% by weight. If the amount of the thickener is too small, the viscosity of the resin composition may not increase. On the other hand, if the amount of the thickener is too large, the viscosity may increase too much to be controlled.

Inorganic fillers, mold release agents, stabilizers, colorants and the like are further added to the unsaturated polyester resin composition.

Examples of the inorganic filler include silica sand, calcium carbonate, talc and clay. The compounding amount of the inorganic filler is 100 to 200 with respect to 100 parts by mass of the mixture of the unsaturated polyester resin, the polymerizable monomer and the low-shrinking agent.
It is preferably part by mass.

As the release agent, zinc stearate, calcium stearate and the like are used. The amount of the releasing agent is preferably 1 to 10% by weight, and more preferably 2 to 10% by weight based on the total amount of the unsaturated polyester resin and the polymerizable monomer.
It is 4% by weight. If the amount of the release agent is too small, the amount of less than 1 part by weight may cause the molded product to stick to the mold, make it difficult to remove the mold, and cause the molded product to be cracked. Further, if the amount of the release agent is too much, the strength of the molded product tends to be lowered.

In addition to the sheet-like foam, a glass fiber layer may be provided on one or both sides of the foam by sprinkling cut glass fibers on the foam on one or both sides, as in the conventional production of SMC. It is possible.

The above unsaturated polyester composition is impregnated with a sheet-like foam, and is subjected to an aging step with a thickener to be thickened to be the SMC of the present invention.

As the sheet-like foam, polyurethane, polyethylene, polypropylene or the like foam is used. The sheet-like foam is impregnated with the unsaturated polyester resin composition into an unsaturated polyester resin composition layer uniformly applied by a doctor blade or the like on the upper and lower carrier films in the same manner as in ordinary SMC coating. It is carried out by continuously supplying a sheet-shaped foam body wound in a roll and passing through an impregnation step. In this step, glass fibers cut by a normal glass roving cutter can be sprinkled on one side or both sides of the sheet foam.

The SMC of the present invention has, on both sides or one side thereof,
A conventional SMC is placed and hot-pressed to form a molded product. The SMC layer containing glass fiber is provided on both sides or one side in order to secure the strength of the molded product. That is, SM using only sheet foam
This is because the strength of C alone is insufficient as a structure such as a bathroom wall panel or floor pan. Since the molded product thus obtained has a foam in the middle thereof, it is provided with heat insulation performance and, in comparison with the conventional SMC molded product,
It has a low specific gravity, can be made lightweight, and can be easily installed. The conventional SMC referred to here is obtained by impregnating a fiber reinforcing material with the above-mentioned unsaturated polyester resin composition and aging the same as above. As the fiber reinforcing material, glass fiber,
Carbonate fiber, aramid fiber, polyvinyl alcohol fiber and the like can be used, and glass fiber is generally used. These fiber reinforcements are used in the form of continuous fibers, woven fabrics, non-woven fabrics, etc., but it is preferable to use roving-shaped ones cut to an appropriate length (for example, 20 to 30 mm). The amount of fiber reinforcement used is
Although it depends on the required strength, it is preferably in the range of 15 to 42% by weight based on the total amount of the unsaturated polyester resin and the polymerizable monomer in the unsaturated polyester resin composition. If the content of the fiber reinforcing agent is less than 15% by mass, the strength of the molded product will decrease, and
If it exceeds 2% by mass, the compound may not be sufficiently impregnated into the fiber reinforcing agent, and on the contrary, the strength as a molded article may be lowered. As the fiber reinforcing material, glass fiber is most preferable.

[0025]

EXAMPLES In the following, Polyset PS-9415 was used as an unsaturated polyester resin diluted with styrene.
(60% by mass unsaturated polyester resin in styrene solution,
Hitachi Chemical Co., Ltd., trade name) and polystyrene (Dencast styrol, Denki Kagaku Kogyo Co., Ltd. trade name) were used as the low-shrinking agent.

Example 1 (Preparation of SMC) 80 parts by mass of an unsaturated polyester resin dissolved in styrene (40 parts by mass of styrene) and 20 parts by mass of a styrene solution of polystyrene dissolved in styrene (30% by mass of polystyrene), and , 100 parts by weight of a mixture of the unsaturated polyester resin diluted with styrene and polystyrene dissolved in styrene, 1 part by weight of t-butyl peroxybenzoate as a curing agent, and 0.05 parts by weight of parabenzoquinone as a polymerization inhibitor. , 4 parts by mass of zinc stearate as a release agent, 130 calcium carbonate as a filler
An unsaturated polyester resin composition was produced by blending parts by mass and 0.8 parts by mass of magnesium oxide as a thickener.
(Production of SMC) The above unsaturated polyester resin composition was impregnated into a flexible polyurethane foam having a thickness of 10 mm and a foaming ratio of 30 times and aged at 40 ° C. for 24 hours to produce SMC. The component ratio of SMC was adjusted to 83% by mass of the unsaturated polyester resin composition and 17% by mass of the polyurethane foam. As the polyurethane foam, a 5 mm thick long roll product of Everlight Slab Foam manufactured by Bridgestone Chemical Co., Ltd. was used. Manufacture of Molded Product Using the SMC obtained above, a 220 cm square flat plate was pressure-heated and molded. The molding conditions are as follows: SMC input weight 1.5 kg, charge area 0.05 m ² (15 cm
Corner), molding pressure 1 MPa, pressure holding time 4 minutes.

Example 2 (Preparation of SMC) 83% by mass of the unsaturated polyester resin composition prepared in Example 1 and polyurethane foam 17
Mass% SMC (hereinafter referred to as foam SMC) was used. Separately, 75% by weight of the unsaturated polyester resin composition is impregnated into 25% by weight of "glass fiber",
The glass fiber-containing SMC was produced by aging at 40 ° C. for 24 hours. “Glass fiber” had a fiber diameter of 13 μm and a roving having a TEX of 4800, which was cut into 1-inch lengths with a roving cutter in the same manner as in a normal SMC manufacturing method, and was scattered on a sheet. A glass fiber-containing SMC was placed on the foam SMC, and a 220 cm square flat plate was pressure-heated and molded. The molding conditions are: SMC input weight 1.5k
g, charging area 0.05 m ² (15 cm square), molding pressure 1 MPa, pressure holding time 4 minutes.

Example 3 (Production of SMC) The foamed SMC produced in Example 1 and the glass fiber-containing SMC produced in Example 2 were used.
A glass fiber-containing SMC was placed on the foam SMC, and a 220 cm square flat plate was pressure-heated and molded. The molding conditions were as follows: SMC input weight 1.5 kg, charge area 0.05 m ² (15 cm square), molding pressure 1 MPa, pressure holding time 4 minutes.

Strength (bending strength) of the obtained SMC molded product,
Table 1 shows the results of measurement of the specific gravity of the molded product and the heat transmission coefficient indicating the heat insulation performance. Test method (1) Specific gravity of molded product Measured with an electronic balance-type specific gravity meter. (2) Bending strength According to JIS K 6911, it was measured by a tensile tester manufactured by Orientec Co., Ltd. (3) Thermal transmission coefficient It was measured by a thermal resistance measuring device manufactured by Ozawa Scientific Co., Ltd.

[0030]

[Table 1] The molded product of the SMC according to the present invention has a low specific gravity of the molded product, is effective in reducing the weight of the product, has a lower heat transmission coefficient than the conventional SMC molded product, and is excellent in heat insulating performance.

[0031]

EFFECTS OF THE INVENTION The SMC according to the present invention has a sheet-like foam layer instead of glass fiber, so that it is superior in heat insulation performance to conventional SMC molded products and has a low specific gravity and a light weight. You can get the goods. Moreover, sufficient strength can be ensured by stacking the conventional SMC on the above SMC.

Claims (3)

[Claims] 1. A sheet molding compound obtained by impregnating a sheet-shaped foam with an unsaturated polyester composition containing an unsaturated polyester resin, a polymerizable monomer, a low-shrinking agent, a curing agent, and a thickening agent. 2. The sheet molding compound according to claim 1, wherein glass fibers are arranged on one side or both sides of the sheet-shaped foam. 3. A method for producing a sheet molding compound molded article, comprising arranging a sheet molding compound containing glass fibers on both sides or one side of the sheet molding compound according to claim 1 or 2, and thermocompressing the sheet molding compound.