JPS6361344B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an unsaturated polyester resin composition, and more particularly to a curable unsaturated polyester resin composition to which a low shrinkage agent is added. [Prior Art] Curable unsaturated polyester resin compositions are, for example, sheet molding compounds (SMC),
It is used in various molded products as a bulk molding compound (BMC) and a compound used in the RIM (Resin Injection Molding) method. This curable unsaturated polyester resin composition is made by adding a polymerizable monomer such as styrene to an unsaturated polyester obtained by polycondensing an unsaturated acid such as maleic acid or fumaric acid with a diol. It contains a catalyst, a reinforcing agent, a low shrinkage agent, an internal mold release agent, a thickener, a filler, a coloring agent and other additives, and is itself used as a molding material. This low-shrinkage agent added to unsaturated polyester resin is intended to prevent shrinkage during molding or to prevent reinforcing agents from rising to the surface of the molded product.
Examples include thermoplastic resin powders such as nylon and polyethylene, polymerizable monomer solutions of acrylic and styrene resins, vinyl acetate resin powders, and three-dimensional acrylic and styrene resin powders. [Problems to be Solved by the Invention] Conventional low-shrinkage agents have achieved some success, but each has its own problems. For example, when a thermoplastic resin powder such as nylon or polyethylene that is poorly soluble in polymerizable monomers is used as a low-shrinkage agent, the dispersibility and stability of the low-shrinkage agent are good, and the composition Although it has excellent uniform coloring properties, it has low compatibility with polymerizable monomers, so its shrinkage reduction effect is insufficient, and it is necessary to use it in combination with other shrinkage reduction agents. In addition, when an acrylic, styrene, or vinyl acetate polymerizable monomer solution is used as a low-shrinkage agent, a sufficient low-shrinkage effect can be obtained, but the dispersibility and stability are poor, resulting in poor compositions. It becomes uniform. Similarly, when acrylic, styrene, or vinyl acetate resin powder is used as a low-shrinkage agent, the low-shrinkage agent dissolves in the polymerizable monomer during mixing, causing the same problems as the solution described above. Conventional three-dimensional acrylic, styrene,
When using vinyl acetate resin powder
1276 Publication), when the crosslinking density is less than 0.5%, the resin rapidly absorbs the polymerizable monomer and swells, thickens, and aggregates, making it impossible to obtain a uniform compound.On the other hand, when the crosslinking density is 0.5% or more, Although a uniform compound can be obtained, a sufficient low shrinkage effect cannot be obtained. This invention was made in order to solve the above-mentioned problems of the prior art, and its purpose is to exhibit a sufficient low shrinkage effect, and to have good dispersibility and stability of the low shrinkage agent. Therefore, it is an object of the present invention to provide an unsaturated polyester resin composition having excellent gloss and coloring uniformity of molded articles. [Means for solving the problem] As a result of various research tests, the present inventors found that
The more effective the shrinkage prevention agent, the worse the uniformity and coloring properties, and the more difficult it is to dissolve and dissolve into the polymerizable monomer component.
After obtaining the knowledge that the particles easily swell, they found that treating the surface of the particles of a low shrinkage agent to suppress or prevent dissolution and swelling caused by the polymerizable monomer would be effective in achieving the object of the present invention, and completed the present invention. I came to the point. That is, the unsaturated polyester resin composition of the present invention is a curable composition comprising an unsaturated polyester and a polymerizable monomer, and has a substance on the surface that is not easily soluble with respect to the polymerizable monomer. It is characterized by containing a low shrinkage agent. In a preferred embodiment of this invention, the low shrinkage agent can be a resin powder that swells with the polymerizable monomer, for example, a resin powder with a swelling degree of 2 to 40. In a preferred embodiment of this invention, the low shrinkage agent is
The resin powder may be three-dimensional with a crosslinking density of 0.01% to 5% and selected from acrylic, styrene, vinyl acetate, and copolymer resins thereof. Here, the crosslinking density is the weight percent of a crosslinking monomer (eg, divinylbenzene, trimethylolpropane trimethacrylate, etc.) copolymerized with the resin used as a low shrinkage agent. In a preferred embodiment of the present invention, the substances that are not easily soluble in the polymerizable monomer are tricalcium phosphate, titanium oxide, calcium carbonate, calcium hydroxide, red iron, carbon black, glass, silica, metal powder, and powder. , cellulose powder, polyacrylonitrile, metal salts of polyacrylic acid, metal salts of polymethacrylic acid, and polyacrylamide. This invention will be explained in more detail. In general, unsaturated polyester resin compositions include ester products of unsaturated dibasic acids or their anhydrides alone or mixtures thereof with diols, and saturated or unsaturated dibasic acids such as diacrylphthalates. It contains a substantially uncrosslinked prepolymer (so-called β-polymer) of a basic acid and an unsaturated alcohol, a polyester selected from a mixture thereof, and a polymerizable monomer. As the unsaturated dibasic acid or its anhydride in the unsaturated polyester resin composition, maleic acid or its anhydride having an ethylenic double bond, fumaric acid, mesaconic acid, itaconic acid or its anhydride, etc. are used. Examples of saturated dibasic acids include phthalic acid, substituted phthalic acids, anhydrides thereof, adipic acid, and the like.
Diols that react with these dibasic acids to form esters include ethylene glycol, diethylene glycol, triethylene glycol,
Propylene glycol, dipropylene glycol, butadiol, etc. are used. Moreover, allyl alcohol and the like are used as the unsaturated alcohol. The reaction conditions for obtaining the above-mentioned polyester from these acids and alcohols may be different, but in any case, the polyester can be prepared by a known method. Further, as the polymerizable monomer, styrene, divinylbenzene, vinyltoluene, vinyl acetate, methyl methacrylate, α-methylstyrene, diacryl phthalate, etc. are used. In addition to the above-mentioned components, the unsaturated polyester resin composition of the present invention contains a low-shrinkage agent having on its surface a substance that is not easily soluble with respect to the polymerizable monomer. As the low-shrinkage agent in this invention, organic polymers conventionally used as low-shrinkage agents can be used, such as polyethylene resin powder, nylon resin powder, acrylic resin powder,
Strenic resin powder, vinyl acetate resin powder, crosslinked acrylic resin powder, crosslinked styrene resin powder, crosslinked vinyl acetate resin powder, polypropylene powder, polyvinyl chloride resin powder,
Polyester resin powder, epoxy resin powder, etc. can be used. Preferred low-shrinkage agents include resin powders that swell with polymerizable monomers, preferably resin powders with a swelling degree of 2 to 40, preferably 5 to 20, such as acrylic, styrene, vinyl acetate, and these. Resin powder such as copolymer system of 0.01 to 30%, preferably 0.01 to 5%
Specific examples include methyl methacrylate-divinylbenzene copolymer resin powder, styrene-divinylbenzene copolymer resin powder, styrene-ethylene glycol dimethacrylate copolymer resin powder, etc. be. In the present invention, the substance that is not easily soluble in the polymerizable monomer adheres to or adheres to the surface of the low-shrinkage agent and serves to suppress or prevent the adverse effects of the polymerizable monomer. There are various types of substances that function in this way, and they can be changed as appropriate depending on the type of polymerizable monomer, low shrinkage agent, unsaturated polyester resin, etc. As a specific example,
For example, tricalcium phosphate, titanium oxide, calcium carbonate, calcium hydroxide, red iron, carbon black, glass powder, silica, inorganic materials such as metal powder, starch, cellulose powder, polyacrylonitrile, metal salts of polyacrylic acid. , metal salts of polymethacrylic acid, polyacrylamide, polyvinyl alcohol, and other organic materials. As a method of attaching or coating the above substance to the surface of the low shrinkage agent resin powder, for example, a method of utilizing an inorganic or organic substance used as a protective colloid during suspension polymerization and allowing it to remain on the surface. , A method in which it is added to an emulsion or suspension during polymerization and dried to adhere or coat the resin surface, a method in which it is coated by seed emulsion polymerization, a method in which a substance powder to be attached to the resin powder of the low shrinkage agent is added and mixed by stirring. There is a method of attaching the material by charging it with electricity. When adhering or coating with the above method, the amount of the above substance added is, for example, approximately 1 to 0.01% by weight for very fine inorganic materials such as colloidal silica, and for organic polymers such as polyzinc methacrylate. 0.3% or more is sufficient to coat the surface of particle-based resin powder of about 0.3μ, and
When three-dimensional polystyrene is subjected to suspension polymerization using tricalcium phosphate as a protective colloid, the effects of the present invention are recognized when the tricalcium phosphate content is 25% or more. The low-shrinkage agent used in the present invention may be a mixture of a conventional low-shrinkage agent and the above-mentioned low-shrinkage agent having a substance that is not easily soluble in the polymerizable monomer on its surface. By using this combination, the uniform coloration and glossiness of the molded article can be improved. In addition to the above components, the unsaturated polyester resin composition may contain fillers, thickeners, curing agents (catalysts), colorants, polymerization inhibitors, and other additives as necessary. Fillers that can be used here include aluminum hydroxide, magnesium carbonate, barium sulfate, calcium sulfate, calcium carbonate, alumina, stone powder, FRP waste, silica sand, glass fiber, clay, kaolin, talc, and the like. As the thickener, metals such as magnesium oxide, magnesium hydroxide, calcium oxide, and lithium oxide, preferably alkaline earth metal oxides and hydroxides, can be used. The curing agent (catalyst) includes t-butyl perbenzoate, cumene hydroperoxide, etc. for high-temperature molding, and cumene hydroperoxide for medium-temperature molding, so that an appropriate curing effect can be obtained at the molding temperature of the unsaturated polyester resin composition. For molding, lauroyl peroxide, methyl isobutyl ketone peroxide, etc. are used, and for medium and low temperature molding, bis-(4-butylcyclohexyl) peroxycarbonate, t-
Butyl peroctoate + Co or Ca accelerator,
For room temperature curing, a combination of methyl ethyl ketone peroxide and an organometallic compound accelerator is used. As the coloring agent, known dyes or pigments are used in types and amounts depending on the desired color tone. If necessary, an internal mold release agent such as zinc stearate, a surface improving agent such as finely powdered polyethylene, etc. may be added to this unsaturated polyester resin composition. [Example] The present invention will be specifically explained with reference to the following examples. Note that "parts" below refer to parts by weight unless otherwise specified. Example 1 Preparation of low shrinkage agent A In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 100 parts of styrene was added.
0.1 part of divinylbenzene, 0.3 part of benzoyl peroxide, 130 parts of industrial water, 15 parts of tricalcium phosphate powder, and 0.3 part of sodium lauryl sulfate were added, and suspension polymerization was carried out in a nitrogen stream for 6 hours according to a conventional method. After the polymerization was completed, the reaction solution was filtered, dried, and sieved to obtain 97 parts of three-dimensional polystyrene having an average particle size of 20μ and a crosslinking density of about 0.1%, in which tricalcium phosphate was evenly adhered to the particle surface. The degree of swelling of this low shrinkage agent A was measured as follows. Precisely weigh 0.5 g of the sample into a colorless glass 20 ml measuring cylinder with an inner diameter of 14 mm, a height of 135 mm, and a graduation of 0.2 ml. After tapping the cylinder several times to avoid air bubbles, gently spread the styrene monomer along the wall and add 20 ml of the sample. Fill it up to the mark. 16 hours 20
Leave it at ℃ and read the height of the swollen gel in ml. Degree of swelling = reading value (ml) x 0.5/amount of sample collected (g
) to calculate the degree of swelling. The results are shown in Table 1. Example 2 Preparation of low shrinkage agent A Polymerization was carried out in the same manner as in Example 1. After the polymerization reaction is complete, 700 g of 5% hydrochloric acid is added to dissolve tricalcium phosphate, and the suspension is washed with water, dried, and sieved to determine the average particle size with nothing attached to the particle surface.
20μ three-dimensional polystyrene 80 with a crosslink density of about 0.1%
I got the department. The swelling degree of low shrinkage agent A was measured in the same manner as in Example 1. The results are shown in Table 1. Example 3 Preparation of low shrinkage agent B Prepared in the same manner as in Example 1 except that 20 parts of titanium oxide powder was used instead of 15 parts of tricalcium phosphate powder, and the average particle size with titanium oxide uniformly attached to the particle surface.
15μ three-dimensional polystyrene 99 with a crosslink density of about 0.1%
I got the department. The degree of swelling was measured for low shrinkage agent B in the same manner as in Example 1. The results are shown in Table 1. Example 4 Preparation of low shrinkage agent
1 part, divinylbenzene 0.4 part, polyvinyl alcohol 0.3 part, and 200 parts of industrial water were added, and suspension polymerization was carried out in a nitrogen stream for 4 hours according to a conventional method. After the polymerization was completed, the suspension was washed with water, dried, and sieved to obtain 78 parts of three-dimensional polymethyl methacrylate having an average particle size of 45 μm and a crosslinking density of about 0.4% with no coating on the particle surface. The swelling degree of this low shrinkage agent B was measured in the same manner as in Example 1. The results are shown in Table 1. Example 5 Preparation of low shrinkage agent C After carrying out suspension polymerization for 4 hours in the same manner as in Example 4,
3 parts of methacrylic acid and 0.3 parts of potassium persulfate were added, and the polymerization was further continued for 1 hour. After the polymerization was completed, 2 parts of calcium hydroxide was added to neutralize the polymethacrylic acid and form a salt. The suspension was evaporated to dryness at 80°C, crushed and sieved using a 200-mesh vibrating sieve, and the particles were coated with calcium salt of polymethacrylic acid on the particle surface, with an average particle size of 45μ and a crosslinking density of approximately 0.4. 80 parts of original polymethyl methacrylate were obtained. The swelling degree of this low shrinkage agent C was measured in the same manner as in Example 1. The results are shown in Table 1. Example 6 Preparation of low-shrinkage agent D 100 parts of low-shrinkage agent B from Example 4 and 10 parts of titanium oxide powder were placed in a steel ball mill (1) and mixed for 24 hours, cross-linked with an average particle size of 45μ with titanium oxide attached to the particle surface. 105 parts of three-dimensional polymethyl acrylate having a density of about 0.4% was obtained. The swelling degree of this low shrinkage agent D was measured in the same manner as in Example 1. The results are shown in Table 1. Example 7 Preparation of low shrinkage agent C Put 200 parts of styrene, 1 part of methacrylic acid, and 0.5 part of benzoyl peroxide into the same equipment as in Example 1, polymerize in a nitrogen stream at 60°C for 5 hours, and make a 35% polystyrene-styrene monomer solution. I got it. The swelling degree of low shrinkage agent C was measured in the same manner as in Example 1. The results are shown in Table 1.

[Table] Example 8 Preparation of unsaturated polyester resin composition A curable resin composition having the formulation shown in Table 2 below was prepared. Compositions Nos. 1 to 8 are within the scope of the present invention, and compositions Nos. 9 to 13 are conventional examples.

【table】

【table】

【table】

[Table] Example 9 Preparation of SMC For compositions 1 to 4 and 9 to 11 of Example 8, other components except magnesium oxide and glass fiber were added to 1
The mixture was placed in an S-type double-arm kneader, kneaded for 20 minutes, and left at 30°C for 20 minutes.The mixed state was visually observed, and the viscosity was measured using a Bruckfield viscometer. Furthermore, magnesium oxide was added and kneaded for 30 minutes to impregnate glass fibers, which were then sandwiched between polyethylene sheets to form a sheet to obtain SMC. After allowing each SMC to stand for 7 days, it was molded at a temperature of 140° C., a pressure of 10 Kg/cm ² and a time of 3 minutes, and stains on the mold, coloring, and surface gloss unevenness were observed, and the shrinkage rate was measured. The results are shown in Table 3. Note that the SMC number corresponds to the composition number.

[Table] Here, the shrinkage rate was determined by measuring the dimensions of the mold and the molded article using a caliper, and the shrinkage rate was determined by the equation: Shrinkage rate = Dimension of the mold - Dimension of the molded article/Dimension of the mold x 100. Example 10 Molded product by RIM method For each of compositions 5 to 8 and 12 to 14 of Example 8, polyester, threatin monomer, cobalt naphthenate,
Zinc stearate and a low shrinkage agent were mixed in this order, and the mixture was left at 30°C for 30 minutes, the mixing state was observed, and the viscosity was measured using a Bruckfield viscometer. Furthermore, acetylacetone peroxide was added, mixed quickly, and poured into a mold containing sheet glass fibers in advance at a temperature of 60℃ and a pressure of 10℃.
It was molded under the conditions of Kg/cm ² and 30 minutes. Dirt on the mold,
The surface lifting and surface gloss of the glass fibers were observed, and the dimensions of the mold and the molded product were measured using calipers, and the shrinkage rate was measured. The results are shown in Table 4. Note that the molded product number corresponds to the composition number.

〔Effect of the invention〕

None of the conventional low-shrinkage agents has sufficient low-shrinkage properties and imparts good dispersibility, uniform coloration, etc. to compositions and molded products. As demonstrated in Examples 9 and 10, the curable unsaturated polyester resin composition of the present invention makes it possible to ensure uniformity in coloring and gloss of molded articles, as well as sufficiently low shrinkage. able to demonstrate.

Claims (1)

[Scope of Claims] 1. A curable composition comprising an unsaturated polyester and a polymerizable monomer, which contains a low-shrinkage agent having a substance that is not easily soluble in the polymerizable monomer on its surface. An unsaturated polyester resin composition characterized by: 2. The composition according to claim 1, wherein the low shrinkage agent is a resin powder swollen by a polymerizable monomer. 3. The composition according to claim 2, wherein the low shrinkage agent is a resin powder having a swelling degree of 2 to 40. 4 Acrylic, styrene, and vinyl acetate based low-shrinkage agents made three-dimensional with a crosslinking density of 0.01 to 5%;
The composition according to claim 1, which is a resin powder selected from these copolymer-based resins. 5 Substances that are not easily soluble in polymerizable monomers are
Claim 1, which is at least one kind of powder selected from tricalcium phosphate, titanium oxide, calcium carbonate, calcium hydroxide, red iron, carbon black, glass, silica, and metal.
The composition according to any one of items 1 to 4. 6 Substances that are not easily soluble in polymerizable monomers are
starch, cellulose, polyacrylonitrile,
Claim 1, which is at least one selected from metal salts of polyacrylic acid, metal salts of polymethacrylic acid, and polyacrylamide.
The composition according to any one of items 1 to 4.