JPH10204193A - Sheet molding compound and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet molding compound having good handleability and being capable of being formed under low pressure to give a molding excellent in hot-water resistance. SOLUTION: Compound coating layer 5 and 6 each of which is a compound obtained from a heat-flowable unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, a chemical thickener and a heat-flowable agent having a melting point of 40-150 deg.C and an apparent viscosity of 50,000-200,000P when measured on the compound except the curing catalyst are formed on both surfaces of the body 4 of a sheet molding compound being one obtained from a fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a chemical thickener and a fibrous reinforcement and having an apparent viscosity of 1,000-5,000P at 30 deg.C as measured on the compound except the fibrous reinforcement and the curing catalyst.

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 which can be thermoformed at a low pressure and a method for producing the same.

[0002]

2. Description of the Related Art A sheet molding compound is a material in which a paste-like resin composition obtained by mixing a liquid unsaturated polyester resin with a curing catalyst, an inorganic filler, a chemical thickener and the like is impregnated into a fiber reinforcing material such as glass fiber. This is a sheet-like molding material obtained by forming a sheet-like fiber-reinforced unsaturated polyester resin composition, aging it at a predetermined temperature for a certain period of time, and thickening it by a chemical reaction, and is widely known as SMC.

[0003] This type of sheet molding compound (SMC) is mainly manufactured by a compression molding method using a wash bowl,
Molded into various products such as bathtubs, waterproof pans, and water tanks. In the compression molding method, molding is generally performed under a molding temperature of 110 to 160 ° C. and a molding pressure of 40 to 100 kg / cm ² .

In such a compression molding method, a large molding machine and various molds are used to increase the size and variety of articles to be applied, resulting in high molding costs. Therefore, the handleability of the sheet molding compound as a molding material (easiness of peeling the release film from SMC, SM
The better the workability of charging C into the mold, the better the cost of molding can be reduced. Also, at the time of compression molding, as described above, 40
Molding is performed at a relatively high pressure of １００100 kg / cm ² , and if compression molding can be performed at a lower pressure, molding costs can be reduced, which can contribute to expansion of applicable products.

[0005] However, when the conventional SMC is molded at a pressure lower than the conventional molding pressure, underfilling occurs, and cavities and pinholes tend to be formed on the surface of the molded product. Nests and pinholes not only impair the appearance of the product, but also adversely affect the mechanical strength and durability of the product. Therefore, various attempts have been made in the past to solve the above-mentioned problems when compression molding is performed at low temperature and low pressure. For example, Japanese Patent Application Laid-Open No. 6-200136 discloses a method of adding a fluidity modifier to enhance the fluidity of a liquid unsaturated polyester resin composition.

[0006]

However, SMCs to which such fluidity modifiers have been added to increase the fluidity generally have poor handling properties. SMC obtained by adding a commercially available viscosity reducing agent (for example, BYK-W995 manufactured by BYK-Chemie, Superdyne-V-203 manufactured by Takemoto Yushi Co., Ltd.) or the like as the fluidity adjusting agent.
However, when a molded article obtained from this SMC is immersed in hot water, it easily discolors and has poor hot water resistance. For this reason, there is a problem in applying SMC to water-related products, which is a large application field.

[0007] The present invention solves the above-mentioned problems of the prior art. It is an object of the present invention to provide a molded article which is easy to handle, can be molded under low pressure, and has excellent hot water resistance. An object of the present invention is to provide a sheet molding compound and a method for manufacturing the same.

[0008]

The sheet molding compound of the present invention comprises a liquid unsaturated polyester resin,
A sheet molding compound obtained from a fiber-reinforced unsaturated polyester resin composition containing a curing catalyst, an inorganic filler, a chemical thickener and a fiber reinforcing material, wherein the compound is obtained by removing the fiber reinforcing material and the curing catalyst from the compound. Has an apparent viscosity of 1,000 to 5,000 at 30 ° C.
On both sides of the body of the sheet molding compound, which is poise,

A liquid unsaturated polyester resin, a curing catalyst,
A compound obtained from a heat-fluid unsaturated polyester resin composition containing a chemical thickener and a heat-fluidizing agent having a melting point of 40 to 150 ° C, wherein the compound obtained by removing a curing catalyst from the compound has an apparent viscosity of 50 at 30 ° C.
A compound coating layer having a thickness of 000 to 200,000 poise is formed (the invention of claim 1).

The method for producing a sheet molding compound according to the present invention is characterized in that a liquid unsaturated polyester resin, a curing catalyst, a chemical thickener and a melting point of 40 to 50 are respectively provided inside one of the release films and inside the other of the release films.
A paste of a heat-fluid unsaturated polyester resin composition containing a heat-fluidizing agent at 150 ° C. is applied, and a liquid unsaturated polyester resin, a curing catalyst, and an inorganic filler are provided between the inner application surfaces of the release films. A paste of a fiber-reinforced unsaturated polyester resin composition containing a thickener and a fiber reinforcing material is sandwiched, and the paste is aged and thickened (the invention of claim 2).

Hereinafter, various compounding materials used in the present invention and the sheet molding compound (hereinafter referred to as S
MC) and its manufacturing method will be described in detail.

Liquid unsaturated polyester resin The liquid unsaturated polyester resin used in the present invention is obtained by polymerizing unsaturated polyester obtained by polycondensing unsaturated dibasic acid and glycol and, if necessary, saturated dibasic acid. This is a mixture obtained by diluting with a hydrophilic vinyl monomer and blending a thermoplastic resin for reducing shrinkage as necessary.

The unsaturated dibasic acids include maleic anhydride, fumaric acid, itaconic acid, citraconic acid and the like. As the glycol, ethylene glycol, diethylene glycol, triethylene glycol,
Propylene glycol, 1,3-butanediol, 1,
Examples thereof include 4-butanediol, 1,6-hexanediol, bisphenol A, hydrogenated bisphenol A, an ethylene oxide adduct of bisphenol A, and neopentyl glycol. Also, as the saturated dibasic acid,
Examples thereof include phthalic anhydride, orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, tetrachlorophthalic acid, and heptic acid.

The above polymerizable vinyl monomers include styrene, methylstyrene, dichlorostyrene, vinyltoluene, vinyl acetate, acrylic acid, methacrylic acid, acrylate, methacrylate, diallyl phthalate, triallyl phthalate and the like. Styrene is particularly preferred. These polymerizable vinyl monomers are usually added to the above liquid unsaturated polyester resin in an amount of 20%.
It is contained in the range of ６０60% by weight.

The thermoplastic resin for reducing shrinkage includes polystyrene, polyvinyl acetate, polymethyl methacrylate, polyethylene, poly ε-caprolactone,
Saturated polyester, polyvinyl chloride, polybutadiene,
Examples include a polystyrene-acrylic acid copolymer, a polystyrene-polyvinyl acetate copolymer, an ethylene-vinyl acetate copolymer, a vinyl chloride-vinyl acetate copolymer, and an acrylonitrile-styrene copolymer. These thermoplastic resins are generally blended with the above liquid unsaturated polyester resin in a range of 30% by weight.

Curing Catalyst The curing catalyst used in the present invention includes tertiary butyl peroxyisobutyrate, tertiary butyl peroxy-2-ethylhexanoate, tertiary amyl peroxy-2-ethylhexanoate, , 4,4,
-Trimethylpentylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, tert-butylperoxy-3,5,5-trimethylhexa High and medium temperature systems composed of organic peroxides such as noate, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, benzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide And a low-temperature curing catalyst.

In particular, a medium-temperature or low-temperature curing catalyst is suitable for shortening the molding cycle and improving productivity. These curing catalysts are generally preferably contained in the range of 0.5 to 5 parts by weight based on 100 parts by weight of the liquid unsaturated polyester resin.

Inorganic filler As the inorganic filler used in the present invention, calcium carbonate,
Examples include aluminum hydroxide, calcium sulfate, glass powder, talc, mica and the like. The particle size of the inorganic filler is
0.1 to 200 μm is preferable, and more preferably 0.5 to 200 μm.
〜60 μm. If the particle size is too small, the viscosity of the unsaturated polyester resin composition will be high, the fiber reinforcement will not be sufficiently impregnated, and air bubbles will be mixed into the SMC and cavities will easily enter the molded product. In addition, the fluidity during molding also decreases. Conversely, if the particle size is too large, the specific surface area of the particles will be small, so that the viscosity of the unsaturated polyester resin composition will be low and the fluidity during molding will increase, but the handleability will decrease.

The inorganic filler is preferably contained in an amount of generally from 30 to 350 parts by weight, more preferably from 50 to 300 parts by weight, based on 100 parts by weight of the liquid unsaturated polyester resin. preferable. If the amount is less than 30 parts by weight, the handleability of the SMC will decrease. Conversely, 350
If the amount is more than the weight part, the viscosity is greatly increased, and it becomes difficult to uniformly mix the inorganic filler and the resin, the cured product becomes brittle, and the mechanical strength decreases. In addition, the fluidity at the time of molding is reduced, and the impregnation property of the fiber reinforcing material is reduced, so that air bubbles are mixed in the SMC and cavities easily enter the molded product.

Chemical Thickener The chemical thickener used in the present invention includes oxides or hydroxides of alkaline earth metals such as magnesium oxide, magnesium hydroxide and calcium hydroxide. These chemical thickeners chemically react with the liquid unsaturated polyester resin upon aging to thicken the liquid unsaturated polyester resin, and generally 0.1 parts by weight based on 100 parts by weight of the liquid unsaturated polyester resin. It is preferably contained in the range of 10 to 10 parts by weight.

Fiber Reinforcing Material The fiber reinforcing material used in the present invention includes glass fiber, carbon fiber, asbestos fiber, whisker, organic synthetic fiber, natural fiber and the like, and glass fiber is particularly preferable in terms of physical properties and price. . These fiber reinforcements are typically 1-80 m long
m, preferably 10 to 50 mm in length. If it is shorter than 1 mm, there is no reinforcing effect, and if it is longer than 80 mm, the viscosity increases and the moldability deteriorates. The directionality of the fibers in the liquid unsaturated polyester resin composition is arbitrary, such as randomized, unidirectional, or X-shaped. In addition, continuous fibers can be used as they are, and mat-like or cloth-like ones can also be used.

These fiber reinforcing materials are preferably contained in the fiber reinforced unsaturated polyester resin composition in the range of 2 to 40% by weight. If the content of the fiber reinforcing material is too small, the handleability of the SMC is reduced, the reinforcing effect is reduced, and the molded product is liable to crack or bend. vice versa,
If the content of the fiber reinforcing material is too large, the viscosity of the SMC increases, and the fluidity during molding decreases.

Heat fluidizer The heat fluidizer used in the present invention melts under heating during the compression molding of SMC and is used to reduce the viscosity of the compound coating layer. S
If the melting point of the MC is too low, it becomes difficult to lower the viscosity of the SMC during hot compression molding. Therefore, in the present invention, the melting point is 4
A heat fluidizer at 0-150 ° C is used.

As the above-mentioned heat fluidizer, a melting point of 40
A lubricant of ~ 150 ° C is used. Examples of such a lubricant include hydrocarbon lubricants such as polyethylene wax and liquid paraffin; higher fatty acid lubricants such as stearic acid; fatty acid amide lubricants such as fatty acid amides and alkylene bis fatty acid amides; monohydric alcohol esters of fatty acids; Ester lubricants such as polyhydric alcohol esters and fatty acid polyglycol esters; alcohol-based lubricants such as aliphatic alcohols, polyhydric alcohols, polyglycols and polyglycerols; and lubricants such as metal soaps.

These heat fluidizers are generally used in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the liquid unsaturated polyester resin.
It is preferably contained in parts by weight, more preferably in the range of 0.5 to 10 parts by weight. If the amount is less than 0.1 part by weight, the effect of lowering the viscosity of the SMC during the heat compression molding may not be sufficiently obtained. If the amount is more than 20 parts by weight, cavities, pinholes and the like may be generated on the surface of the molded product.

In particular, the following six types of compounds (a) to (f) are preferably used as the heat fluidizer in consideration of the initial handling property of SMC at room temperature and the viscosity lowering property during compression molding. Used. (A) Monohydric aliphatic alcohol having a melting point of 40 to 100 ° C (b) Sorbitan fatty acid ester having a melting point of 40 to 100 ° C (c) Glycerin fatty acid ester having a melting point of 40 to 100 ° C (d) Neopentyl type having a melting point of 40 to 120 ° C Polyol fatty acid ester (e) Higher alcohol fatty acid ester having a melting point of 40 to 120 ° C (f) Fatty acid amide having a melting point of 80 to 150 ° C

The compounds (a) to (f) will be described in detail below. (A) Monovalent aliphatic alcohol A monovalent aliphatic alcohol is a compound in which one hydrogen of an aliphatic hydrocarbon is substituted with a hydroxyl group, and has a melting point of 40%.
~ 100 ° C. Preferably, it has 10 to 3 carbon atoms.
A compound in which hydrogen bonded to the terminal carbon of an aliphatic hydrocarbon of No. 6 (especially preferably 10 to 25 from the viewpoint of industrial availability stability) is substituted with a hydroxyl group is used. As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

Specific examples include cetyl alcohol, stearyl alcohol, behenyl alcohol and the like. These can be used alone or in combination with each other.

The melting point of the monohydric aliphatic alcohol is from 40 ° C.
100 ° C. Preferably it is 45 to 80 degreeC. 4
If the temperature is lower than 0 ° C., the handleability of the material before molding is reduced. If the temperature is higher than 100 ° C., the effect of lowering the viscosity during hot compression molding is reduced.

(B) Sorbitan fatty acid ester Sorbitan fatty acid ester is obtained by esterifying sorbite (molecular formula: C ₆ H ₁₄ O ₆ ), which is a hexavalent alcohol, with a fatty acid, and has a melting point of 40 to 100 ° C. As the fatty acid, a compound in which hydrogen bonded to a terminal carbon of an aliphatic hydrocarbon having preferably 10 to 36 carbon atoms (especially preferably 10 to 25 in view of industrial availability) is substituted with a carboxyl group is used. . As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

Specific examples include sorbitan palmitate, sorbitan stearate, sorbitan tristearate, sorbitan behenate, sorbitan tribehenate and the like.

The melting point of the sorbitan fatty acid ester is 40 ° C.
１００100 ° C. Preferably it is 50 to 80 degreeC.
If it is lower than 40 ° C., the handleability of the material before molding is reduced, and if it is higher than 100 ° C., the effect of lowering the viscosity during hot compression molding is reduced.

(C) Glycerin fatty acid ester Glycerin fatty acid ester is obtained by esterifying glycerin, which is a trihydric alcohol, with a fatty acid, and has a melting point of 4%.
0-100 ° C. As the fatty acid, a compound in which hydrogen bonded to a terminal carbon of an aliphatic hydrocarbon having preferably 10 to 36 carbon atoms (especially preferably 10 to 25 in view of industrial availability) is substituted with a carboxyl group is used. . As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

Specific examples include glycerin monopalmitate, glycerin monostearate, glycerin monooleate, glycerin monobehenate, glycerin mono 1
2-hydroxystearate, glycerin monocaprate, glycerin monolaurate, glycerin monodipalmitate, glycerin monodistearate, glycerin ditristearate, glycerin monodiolate, glycerin monodibehenate, glycerin mono
Di-12-hydroxystearate and the like.

The melting point of glycerin fatty acid ester is 40 ° C.
１００100 ° C. Preferably it is 50 to 80 degreeC.
If it is lower than 40 ° C., the handleability of the material before molding is reduced, and if it is higher than 100 ° C., the effect of lowering the viscosity during hot compression molding is reduced.

(D) Neopentyl polyol fatty acid ester Neopentyl polyol fatty acid ester is neopentyl glycol (also known as 2,2-dimethyl-1,3-
Propanediol), neopentyltriol (alias:
2-hydroxymethyl-2-methyl-1,3-propanediol) or neopentyltetraol (also known as pentaerythritol) neopentyl polyol esterified with a fatty acid, or these neopentyl polyols are ether-bonded Is a product obtained by esterifying a dimer linked by a fatty acid with a fatty acid and having a melting point of 40 to 120 ° C. Further, a neopentyl-based polyol obtained by esterifying two or more hydroxyl groups is preferable.

The fatty acid preferably has 10 to 36 carbon atoms (especially 10 to 2 carbon atoms from the viewpoint of industrial availability).
5 is preferred) in which the hydrogen bonded to the terminal carbon of the aliphatic hydrocarbon is replaced with a carboxyl group. As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

In particular, a fatty acid ester of pentaerythritol or a fatty acid ester of dipentaerythritol is used. Specific examples include pentaerythritol stearic acid ester, pentaerythritol behenic acid ester, dipentaerythritol stearic acid ester, and dipentaerythritol behenic acid ester.

The melting point of the neopentyl polyol fatty acid ester is from 40 ° C. to 120 ° C. Preferably 50 ° C.
100 ° C. If it is lower than 40 ° C., the handleability of the material before molding is reduced, and if it is higher than 120 ° C., the effect of lowering the viscosity during hot compression molding is reduced.

(E) Higher alcohol fatty acid ester The higher alcohol fatty acid ester is obtained by esterifying a higher alcohol and a fatty acid. The higher alcohol is a compound in which hydrogen bonded to a terminal carbon of an aliphatic hydrocarbon having 10 to 36 carbon atoms (especially preferably 10 to 25 in view of industrial availability) is substituted with a hydroxyl group. As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

Fatty acids are those having 10 to 36 carbon atoms (especially preferably 10 to 25 in view of industrial availability).
Is a compound in which hydrogen bonded to the terminal carbon of the aliphatic hydrocarbon is replaced by a carboxyl group. As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

Usually, both higher alcohols and fatty acids are monovalent compounds, and monoester compounds containing these as constituents are used. Specific examples include stearyl stearate, behenyl behenate, cetyl myristate, and the like. These can be used alone,
They can be used in combination.

The melting point of the higher alcohol fatty acid ester is 4
0 ° C to 120 ° C. Preferably it is 50 to 100 degreeC. If the temperature is lower than 40 ° C., the handleability of the material before molding is reduced. If the temperature is higher than 120 ° C., the effect of lowering the viscosity during hot compression molding is reduced.

(F) Fatty acid amide Fatty acid amide is an amide derived from ammonia or an amino compound and a fatty acid.
It is at 50 ° C. The fatty acid preferably has 10 to 36 carbon atoms (particularly 10 to 36 carbon atoms from the viewpoint of industrial availability).
To 25) are used in which the hydrogen bonded to the terminal carbon of the aliphatic hydrocarbon is substituted with a carboxyl group. As the aliphatic hydrocarbon, any of a saturated hydrocarbon and an unsaturated hydrocarbon may be used, and any of a branched or linear hydrocarbon may be used. Preferably, a linear saturated hydrocarbon is used.

As specific examples, stearic acid amide, behenic acid amide, ethylenebisstearamide, ethylenebis (hydroxystearamide), ethylenebisoleic acid amide, ethylenebiserucic acid amide and the like are used.

The melting point of the fatty acid amide is between 80 ° C. and 150 ° C. Preferably it is 90 to 145 ° C. If the temperature is lower than 80 ° C., the handleability of the material before molding is reduced,
If the temperature is higher than ℃, the effect of lowering the viscosity during hot compression molding is reduced.

Other Compounding Materials In the present invention, in addition to the above-mentioned various compounding materials, compounding agents used in ordinary sheet molding compounds, such as a releasing agent, a stabilizer, and a coloring agent, if necessary, are contained. Is also good. Here, as the release agent, zinc stearate, calcium stearate, or the like is usually used.
As the stabilizer, hydroquinone, parabenzoquinone and the like are usually used. As the coloring agent, titanium dioxide, carbon black, phthalocyanine blue, red iron oxide, and the like are used.

Sheet Molding Compound Body In the present invention, the sheet molding compound body comprises the above-mentioned liquid unsaturated polyester resin, a curing catalyst,
It is prepared by aging and thickening a fiber-reinforced unsaturated polyester resin composition containing an inorganic filler, a chemical thickener and a fiber reinforcing material, and if necessary, other compounding materials at a predetermined temperature for a certain period of time. . Generally, the thickness of the sheet molding compound body is preferably in the range of 1 to 5 mm.

Compound coating layer In the present invention, the compound coating layer comprises the above-mentioned liquid unsaturated polyester resin, a curing catalyst, a chemical thickener, a heat fluidizer having a melting point of 40 to 150 ° C, and if necessary, other components. It is prepared by aging and thickening a thermofluid unsaturated polyester resin composition containing the compounding material at a predetermined temperature for a certain period of time. In general, the thickness of the compound covering layer is preferably in the range of 10 to 30% of the thickness of the sheet molding compound body. When the thickness is less than 10%, the compound coating layer cannot adhere to the sheet molding compound main body, and the handleability is reduced. On the other hand, when the thickness is more than 30%, the proportion of the compound coating layer becomes large, and the fiber reinforcing material as a whole is increased. , The mechanical strength of the molded article may be reduced. Further, there is a possibility that the molded product may be discolored after immersion in hot water.

Apparent viscosity of compound In the present invention, the apparent viscosity of the compound is determined by using a flow tester (constant load extrusion type thin tube rheometer), die: inner diameter 1 mm × length 10 mm, temperature: 30 ° C., pressure:
This is a value measured under the condition of 50 kgf / cm ² . As such a flow tester, for example, there is a Shimadzu flow tester CFT-500C.

The apparent viscosity of the compound (thickened by a chemical thickener) obtained by removing the fiber reinforcing material and the curing catalyst from the sheet molding compound body is as follows:
Must be 1,000-5,000 poise at 30 ° C. If the apparent viscosity is less than 1000 poise at 30 ° C., it is difficult to maintain the shape as a molding material. Conversely, if it exceeds 5,000 poise at 30 ° C., the fluidity under low-pressure compression molding is reduced, and the underfill may occur. A more preferred range is 3,000 to 4,500 poise at 30 ° C. The adjustment of the apparent viscosity is performed by aging. For example, it can be carried out by adjusting the amount and type of the chemical thickener, or by adjusting the aging time and temperature.

The apparent viscosity of the compound (thickened with a chemical thickener) obtained by removing the curing catalyst from the compound coating layer is 50,000-200, at 30 ° C.
Must be 000 poise. This apparent viscosity is
If the viscosity is smaller than 50,000 poise at 30 ° C., the SMC main body cannot be held firmly, and the handleability decreases. Conversely, 20
Above 0000 poise not only adversely affects the fluidity of the SMC body under low pressure compression molding, but also impairs the fluidity of the layer itself. The adjustment of the apparent viscosity is performed by aging. For example, it can be carried out by adjusting the amount and type of the chemical thickener, or by adjusting the aging time and temperature.

The sheet molding compound of the present invention
Specific Configuration of the Mold The sheet molding compound of the present invention has the compound covering layer formed on both surfaces of the sheet molding compound body. FIG. 1 is a sectional view showing an example of the sheet molding compound of the present invention. Here, a sheet molding compound 3 is sandwiched between one release film 1 and the other release film 2. The sheet molding compound 3 has a structure in which compound covering layers 5 and 6 are provided on both surfaces of the sheet molding compound body 4.

The sheet molding compound of the present invention
Specific Manufacturing Method of Molds Various methods are employed to manufacture the sheet molding compound of the present invention. For example, a sheet-like fiber-reinforced unsaturated polyester resin obtained by impregnating a fiber-reinforced material such as glass fiber with a paste-like resin composition obtained by mixing a liquid unsaturated polyester resin with a curing catalyst, an inorganic filler, a thickener, and the like. The resulting composition is aged and thickened to prepare a sheet molding compound body. Then, on both surfaces of the compound body, a liquid unsaturated polyester resin, a curing catalyst, a thickener and a heat-fluid unsaturated polyester resin composition containing a heat-fluidizing agent having a melting point of 40 to 150 ° C. are applied, The sheet molding compound of the present invention can be produced by aging and thickening.

A preferred production method is that, as in the production method of the present invention, a liquid unsaturated polyester resin, a curing catalyst, a thickener and a melting point of 40 are provided inside one release film and inside the other release film, respectively. A heat-fluid unsaturated polyester resin composition containing a heat-fluidizing agent at ~ 150 ° C is applied. Then, a fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a thickener and a fiber reinforcing material is sandwiched between application surfaces on the inner side of each of the release films. This is a method for producing the sheet molding compound of the present invention by aging and thickening.

A specific example of such a manufacturing method will be described with reference to FIGS. However, the manufacturing method of the sheet molding compound shown in FIGS. 2 and 3 is as follows.
Only two examples of the manufacturing method of the present invention are shown, and the present invention is not limited thereto.

FIG. 2 is a side view for explaining an example of the manufacturing method of the present invention. In FIG. 2, one release film 12 is supplied from a roll 11. Rollers 14, 1
5 are arranged at a predetermined distance, and rollers 14,
An endless conveyor belt 13 is stretched around the reference numeral 15. The transport belt 13 is circulated in the direction of arrow A shown in the figure. The release film 12 is moved from the roller 14 side to the transport belt 13.
The paper is sent upward, is conveyed on the conveyor belt 13, and moves toward the take-up roll 16.

First, between the rollers 14 and 15,
A heat-fluid unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, a thickener and a heat-fluidizing agent having a melting point of 40 to 150 ° C. is supplied from a tank 17 disposed above and peeled off. It is applied to the inside (upper surface) of the film 12. Next, an unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler and a thickener is supplied from a tank 18 disposed above, applied to the application surface, and 19 makes the thickness of the unsaturated polyester resin composition constant. Thereafter, the fiber reinforcing agent 20 is sprayed on the application surface of the unsaturated polyester resin composition. Fiber reinforcement 2
0 is supplied by cutting the glass roving into a fixed length by the rotary cutter 21.

Further, after the fiber reinforcing material 20 is sprayed, the other release film 23 is supplied from the roll 24, and at the position where the roller 22 is disposed, the release film 23 is also provided on the inside (upper surface) of the release film 23. Arranged tank 2
5, a heat-fluid unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, a thickener and a heating fluidizing agent having a melting point of 40 to 150 ° C. is supplied and applied, and is further disposed above An unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler and a thickener is supplied and applied from the tank 26, and the unsaturated polyester resin is applied by a doctor blade 29. The thickness of the composition is constant. Therefore, after the fiber reinforcing material 20 is sprayed, the heat-fluid unsaturated polyester resin composition and the unsaturated polyester resin composition are applied to the inside (upper surface) of the portion where the roller 22 is disposed. The peeled films 23 are superposed.

In this manner, one of the release films 12
Inside and the inside of the other release film 23, a liquid unsaturated polyester resin, a curing catalyst, a thickening agent and a heat-fluid unsaturated polyester resin composition containing a melting agent having a melting point of 40 to 150 ° C., respectively. A fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a thickener and a fiber reinforcing material is sandwiched between the applied surfaces of the release films. Is transported on the transport belt 13, and a plurality of pairs of sandwiching rolls 27, 2
The fiber reinforcement 19 is impregnated with the unsaturated polyester resin composition. Then, by passing between the sandwiching rolls 27, 27, an SMC is formed between the release films 12, 13.

Thereafter, the sheet 28 obtained as described above is taken up on the take-up roll 16 and maintained at a predetermined temperature for a predetermined time to be aged and thickened, as shown in FIG. Thus, a sheet molding compound 3 having a structure in which the compound coating layers 5 and 6 are provided on both surfaces is obtained. The apparent viscosity of the compound is adjusted by the aging conditions, and the aging condition is the same as the aging condition for measuring the apparent viscosity of the compound.

Here, S wound by the winding roll 16
To thicken MC, it is usually wrapped in a polyethylene film or the like so that polymerizable monomers such as styrene do not volatilize, for example, in an aging room adjusted to a temperature of 25 to 50 ° C. for half a day to 2 days. It is done by storing.

FIG. 3 is a side view for explaining another example of the manufacturing method of the present invention. In the manufacturing apparatus shown in FIG. 3, one release film 32 is supplied from a roll 31. Rollers 34 and 35 are arranged at a predetermined distance,
An endless transport belt 33 is stretched over rollers 34 and 35. The transport belt 33 is circulated in the direction of arrow A shown in the figure. The release film 32 is sent out onto the transport belt 33 from the roller 34 side, is transported on the transport belt 33, and moves toward the take-up roll 36.

First, between the rollers 34 and 35,
From a tank 37 disposed above, a heat-fluid unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, a thickener, and a heat-fluidizing agent having a melting point of 40 to 150 ° C. is supplied to a release film 32. Is supplied to the inside (upper surface) of the substrate and applied. Next, an unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler and a thickener is supplied between a pair of main rolls 38 and 39 from a slit of a supply device (not shown). While also supplying the fiber reinforcement 40, while kneading both,
The fiber reinforcing material 40 is impregnated with the unsaturated polyester resin composition. The fiber reinforcement 40 is a rotary cutter-4.
In step 1, the glass roving is supplied by cutting it into a fixed length. Thus, the main rolls 38, 3
A fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a thickener, and a fiber reinforcing material is applied to the release film 32 from 9 spaces.

Thereafter, similarly to the case of the manufacturing apparatus shown in FIG. 2, the other release film 43 is supplied from the roll 42, and the inside (upper surface) of the release film 43 is also disposed upward from the tank 44. , Liquid unsaturated polyester resin,
A heat-fluid unsaturated polyester resin composition containing a curing catalyst, a thickener and a heat-fluidizing agent having a melting point of 40 to 150 ° C is supplied and applied.

In this manner, one of the release films 32
The inside of the other and the inside of the other release film 43, respectively, a liquid unsaturated polyester resin, a curing catalyst, a thickener and a heat-fluid unsaturated polyester resin composition containing a melting agent having a melting point of 40 to 150 ° C. A fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a thickener and a fiber reinforcing material is sandwiched between the applied surfaces of the release films. Is transported on the transport belt 33, and a plurality of pairs of sandwiching rolls 46, 4
The pressure is applied between 6 and the fiber reinforcement 40 is impregnated with the unsaturated polyester resin composition. Then, by passing between the sandwiching rolls 46, 46, an SMC is formed between the release films 32, 43.

Thereafter, the sheet obtained as described above is wound on a wind-up roll 36, kept at a predetermined temperature for a predetermined time and aged and thickened, as shown in FIG. A sheet molding compound 3 having a structure in which the compound coating layers 5 and 6 are provided on both surfaces is obtained.

[0068]

According to the sheet molding compound of the present invention, a sheet obtained from a fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a chemical thickener and a fiber reinforcing material. -Tomo-
A sheet molding compound body, which is a compounding compound and has an apparent viscosity of 1,000 to 5,000 poise at 30 ° C. excluding the fiber reinforcing material and the curing catalyst from the compound, the apparent viscosity of the compound is set to be low. As a result, the fluidity under low pressure conditions under heating during compression molding is enhanced.

On the other hand, a compound obtained from a heat-fluid unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, a chemical thickener and a heat fluidizer having a melting point of 40 to 150 ° C. A compound coating layer having an apparent viscosity of 50,000 to 200,000 poise at 30 ° C., excluding the curing catalyst from the compound, has a high apparent viscosity of the compound. Properties (e.g., easy release of the release film from the SMC, easy operation when the SMC is put into the mold). Moreover, the compound coating layer does not hinder the fluidity of the SMC body because the heat fluidizing agent contained therein melts under heating during compression molding to lower the viscosity of the compound coating layer.

According to the method for producing a sheet molding compound of the present invention, the liquid unsaturated polyester resin, the curing catalyst, the chemical thickener and the melting point of 40 to 50% are provided inside one release film and inside the other release film, respectively.
A heat-fluid unsaturated polyester resin composition containing a heat-fluidizing agent at 150 ° C. is applied, and a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a chemical Since the fiber-reinforced unsaturated polyester resin composition containing a thickener and a fiber reinforcing material is sandwiched and matured and thickened, an SMC that can be compression-molded under low pressure conditions as described above can be efficiently obtained.

[0071]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The advantages of the present invention will be described below with reference to examples and comparative examples of the present invention. Examples 1 to 8 Preparation of Liquid Unsaturated Polyester Resin Composition 70 parts by weight of liquid polyester resin obtained by diluting an unsaturated polyester obtained by polycondensing fumaric acid, isophthalic acid and propylene glycol with a styrene monomer, 10 parts by weight of polystyrene Parts, 150 parts by weight of calcium carbonate (average particle size: 2 μm) as an inorganic filler, 5 parts by weight of zinc stearate as a releasing agent, magnesium oxide as a chemical thickener, and Kayabutyl B as a curing catalyst (Akazo Chemicals Co., Ltd.) Tertiary butyl peroxybenzoate: 10 hour half-life temperature 105 ° C) or TMPO-7
0 (2,4,4-trimethylpentylperoxy-2-ethylhexanoate manufactured by Kayaku Akzo Co., Ltd .: 10-hour half-life temperature of 64 ° C.) was blended in the ratios shown in Tables 1 and 2, and the mixture was added to a stirrer. The mixture was sufficiently mixed and kneaded to prepare a liquid unsaturated polyester resin composition.

The heat-fluid unsaturated polyester resin composition
Preparation: 70 parts by weight of a liquid polyester resin obtained by polycondensing fumaric acid, isophthalic acid and propylene glycol with a styrene monomer, 10 parts by weight of polystyrene, 30 parts by weight of polystyrene, and calcium carbonate as an inorganic filler (Average particle size 2 μm) 150 parts by weight, 1.0 part by weight of magnesium oxide as a chemical thickener, and Kayabutyl B or TM as a curing catalyst
PO-70 was blended in the proportions shown in Tables 1 and 2, and stearyl alcohol (melting point 56-60
C) or sorbitan tribehenate (melting point 66-72)
C) or glycerin monostearate (melting point 63-68)
C) or stearyl stearate (melting point: 55 ° C.) in the proportions shown in Tables 1 and 2, and these were sufficiently mixed and kneaded with a stirrer to prepare a heat-fluid unsaturated polyester resin composition.

Production of Sheet Molding Compound Using the SMC production equipment shown in FIG. 2, the above-mentioned heat-fluid unsaturated polyester resin composition was supplied, glass fiber was used as a fiber reinforcing material, and fiber length was used. The cutting width and the number of revolutions of the roving cutter are set so that the glass fiber content is 25 mm and the glass fiber content is 28% by weight. The above-mentioned liquid unsaturated polyester resin composition is impregnated into the glass fiber, and the roll is taken up. Then, the SMC held between a pair of release films was wound up, covered entirely with a polyethylene film, and aged for 24 hours in an aging room adjusted to a temperature of 40 ° C. In this way, as shown in FIG. 1, an SMC having a structure in which the compound coating layers 5 and 6 were provided on both surfaces of the sheet molding compound body 4 was obtained. The thickness of the sheet molding compound main body 4 is 2.5 mm.

For the compound obtained by removing the glass fiber and the curing catalyst from the sheet molding compound body 4 and the compound obtained by removing the curing catalyst from the compound coating layers 5 and 6, a Shimadzu flow tester CFT-500C was used. The apparent viscosity at 30 ° C. was measured and the results are shown in Tables 1 and 2.

Performance of Sheet Molding Compound
Evaluation A 300-ton press molding machine (low pressure specification) manufactured by Kawasaki Yuko Co., Ltd. was used, and a mini-bus mold (650 mm long × 65 mm wide) was used as a molding die.
0 mm x depth 270 mm) and the upper mold (cavity-
Side) and the lower die (core side) are heated to a predetermined temperature by an electric heater, and SMC (4.5 kg in total) cut into 200 mm in length and 200 mm in width is charged on this,
Molding was performed by applying pressure at a predetermined pressure. In this case, Examples 1 to
4 and Examples 7 and 8, the upper mold (cavity side) temperature was set to 135 ° C., and the lower mold (core side) temperature was set to 145 ° C.
Molding was performed at a molding pressure of 10 kg / cm ² and a dwell time of 4 minutes. In Examples 5 and 6, molding was performed at an upper mold (cavity side) temperature of 90 ° C., a lower mold (core side) temperature of 90 ° C., a molding pressure of 10 kg / cm ² , and a dwelling time of 12 minutes.

Tables 1 and 2 show the filling rate and the filling time for forming the SMC as described above. The filling rate indicates the ratio of the developed area of the obtained molded article to the developed area of the molding die. For example, when the filling rate is 100%, it is confirmed that the SMC is a molded article that is surely along the molding die. Is shown.
In addition, the filling time indicates the time required from the time when the mold at the time of pressure molding comes into contact with the SMC until the mold is closed,
The shorter the value, the higher the fluidity of the SMC.

Tables 1 and 2 show the handleability when molding the SMC as described above. Regarding the handleability, the removability (easiness of peeling) of the release film from the SMC was sensory evaluated as ○ (easy to peel) and × (hard to peel). As another evaluation criterion of handleability, assuming workability when the SMC is put into the mold, the degree of deformation when held by hand for 30 seconds is indicated by ○ (almost no deformation), ×
(It was considerably deformed) and the sensory evaluation was performed.

Further, the obtained molded product (minibus) was
Immerse in hot water of 0 ° C for 300 hours,
2 is shown. The hot water resistance was measured on the immersion surface using a color difference meter (color analyzer TC-1800 manufactured by Tokyo Denshoku Co., Ltd.)

Comparative Example 1 An SMC was prepared and its performance was evaluated in the same manner as in Example 1 except that no compound coating layer was provided. Table 2 shows the results.

COMPARATIVE EXAMPLE 2 Except that no compound coating layer was provided and 0.7 parts by weight of magnesium oxide was used as a chemical thickener in the SMC body.
An SMC was manufactured in the same manner as in Example 1, and the performance was evaluated. Table 2 shows the results.

Comparative Example 3 An SMC was prepared in the same manner as in Example 7 except that 0.1 parts by weight of magnesium oxide was used as a chemical thickener, and its performance was evaluated. Table 2 shows the results.

COMPARATIVE EXAMPLE 4 When a liquid unsaturated polyester resin composition was prepared without providing a compound coating layer, 5 parts by weight of a commercially available viscosity reducing agent (BYK-W995 manufactured by BYK-Chemie Co., Ltd.) was added and sufficiently stirred with a stirrer. Mixing and kneading were performed to obtain a liquid unsaturated polyester resin composition. Using this liquid unsaturated polyester resin composition, an SMC was prepared in the same manner as in Example 1, and its performance was evaluated. Table 2 shows the results.

[0083]

[Table 1]

[0084]

[Table 2]

[0085]

As described above, the sheet molding compound of the present invention can improve the fluidity under low pressure conditions by lowering the viscosity of the SMC body,
By providing a relatively high-viscosity compound coating layer on both sides of the main body, the release film can be easily peeled off, while the low-viscosity SMC body in the inner layer also plays a role, ensuring easy handling of the SMC as a whole. did.

The relatively high-viscosity compound coating layer formed on both surfaces of the SMC main body is solid at room temperature due to the addition of a heat fluidizing agent. However, since the viscosity of the coating layer itself is reduced, the fluidity of the SMC body during the heat compression molding is not impaired.

Therefore, according to the sheet molding compound of the present invention, for example, 5-35 kg / cm
^{2 Even} if compression molding is performed under low pressure conditions, preferably about 5 to ²⁰ kg / cm ² , a good molded product can be obtained. Further, a heat fluidizer is added to the compound coating layer.
Since the thickness of the coating layer is smaller than that of the C body and the amount of the heat fluidizer added is very small relative to the entire SMC, the durability of the molded product obtained by hot compression molding, such as hot water resistance, is improved. There is no loss.

Further, according to the method of manufacturing a sheet molding compound of the present invention, the liquid unsaturated polyester resin, the curing catalyst, the chemical thickener and the melting point are provided inside one of the release films and inside the other release film, respectively. A heat-fluid unsaturated polyester resin composition containing a heat-fluidizing agent at 40 to 150 ° C is applied, and a liquid unsaturated polyester resin,
Sandwiching a fiber-reinforced unsaturated polyester resin composition containing a curing catalyst, an inorganic filler, a chemical thickener and a fiber reinforcing material,
Since this is aged and thickened, SMC that can be compression-molded under low pressure conditions as described above can be efficiently obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a sheet molding compound of the present invention.

FIG. 2 is a side view for explaining an example of a method for manufacturing a sheet molding compound of the present invention.

FIG. 3 is a side view for explaining another example of the method for manufacturing a sheet molding compound of the present invention.

[Description of Signs] 1 Release film 2 Release film 3 Sheet molding compound 4 Sheet molding compound body 5 Compound coating layer 6 Compound coating layer

Claims (2)

[Claims] 1. A sheet molding compound obtained from a fiber-reinforced unsaturated polyester resin composition containing a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, a chemical thickener and a fiber reinforcing material. A liquid unsaturated polyester resin, a curing catalyst, and a chemical additive, on both surfaces of a sheet molding compound body having an apparent viscosity of 1,000 to 5,000 poise at 30 ° C. excluding the fiber reinforcing material and the curing catalyst from the compound. A compound obtained from a heat-fluid unsaturated polyester resin composition containing a tackifier and a heat-fluidizing agent having a melting point of 40 to 150 ° C, wherein the compound obtained by removing the curing catalyst from the compound has an apparent viscosity of 30 ° C. 50,000-20
A sheet molding compound comprising a compound covering layer having a thickness of 0000 poise. 2. A liquid unsaturated polyester resin, a curing catalyst, a chemical thickener and a melting point of 40 to 150 ° C., respectively, inside one release film and inside the other release film.
A heat-fluid unsaturated polyester resin composition containing a heat-fluidizing agent is applied, and a liquid unsaturated polyester resin, a curing catalyst, an inorganic filler, and a chemical thickener are applied between the inner coating surfaces of the release films. A method for producing a sheet molding compound, comprising sandwiching a fiber-reinforced unsaturated polyester resin composition containing an agent and a fiber reinforcing material, and aging and thickening the composition.