JPH0135004B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an unsaturated polyester resin that has a low shrinkage rate upon curing, and specifically relates to a one-component low shrinkage unsaturated polyester resin composition. When the unsaturated polyester resin is cured, the
It is accompanied by a volumetric contraction of about 10%. Such curing shrinkage causes many defects in resin mortar and resin concrete made of glass fiber reinforced molding compounds or sand, etc., such as impeding the surface smoothness of the molded product due to embossment of the reinforcing material, and causing warping and cracking. Cause. By the way, as a method of reducing curing shrinkage of the unsaturated polyester resin, a method of adding various thermoplastic resins is generally employed. Typical thermoplastic resins include polystyrene, acrylic resin, polyvinyl acetate, and saturated polyester. In this case, when uncured unsaturated polyester resin and thermoplastic resin added as a low-shrinkage agent are mixed, there is a type in which they are uniformly miscible (one-component type), and a type in which they phase separate (two-component type). type). Two-component types are widely used, but when mixed and left for a long time, the thermoplastic resin separates into layers and loses its low shrinkage effect. There are problems such as requiring a large amount of thermoplastic resin and causing a decrease in the strength of the molded product. On the other hand, 1
The liquid type has problems such as its low shrinkage mechanism is complex, there is no suitable thermoplastic resin, the composition and molecular weight of the unsaturated polyester are extremely limited, and the low shrinkage is insufficient. Polyvinyl acetate is a typical one-component low-shrinkage agent.
However, it was found that sufficient shrinkage reduction effects were only observed for relatively low-reactivity, high-molecular-weight unsaturated polyesters, which is thought to be due to too good compatibility with unsaturated polyesters. . In order to solve these drawbacks, the present invention aims to provide a low-shrinkage unsaturated polyester resin composition that sufficiently suppresses shrinkage due to curing and has excellent solution stability that can be applied to a wide range of unsaturated polyesters. It is something to do. That is, the present invention comprises (A) 95 to 50% by weight of a copolymer of vinyl acetate and an alkyl methacrylate or alkyl acrylate, (B) an unsaturated polyester, and (C) An unsaturated monomer that can be copolymerized with an unsaturated polyester and is liquid at room temperature selected from styrene, chlorostyrene, and alkyl methacrylate, and (A), (B), and (C) are It is characterized by being uniformly miscible with each other. In the present invention, as the methacrylic acid alkyl ester in the copolymer which is component (A), for example, methyl methacrylate, ethyl methacrylate, etc. are used, and as the acrylic acid alkyl ester, for example, methyl acrylate, ethyl acrylate, etc. are used. can do. In the copolymer that is component (A), the content of the methacrylic acid alkyl ester or acrylic acid alkyl ester component is from 5% by weight.
A range of up to 50% by weight is suitable. The reason for this is that if it is less than 5% by weight, it is difficult for the copolymer to exhibit its full effect, whereas if it exceeds 50% by weight,
This is because the compatibility with unsaturated polyester may decrease. A particularly preferred content ranges from 10 to 30% by weight. Furthermore, the molecular weight of this copolymer is preferably in the range of 10,000 to 100,000.
This is because the low shrinkage effect is not sufficient outside this range. A particularly preferred molecular weight is in the range of 20,000 to 50,000. In the present invention, the unsaturated polyester as component (B) is produced from raw materials such as unsaturated polycarboxylic acids, saturated polycarboxylic acids, and polyhydric alcohols.
Examples of such unsaturated polycarboxylic acids include maleic anhydride, fumaric acid, itaconic acid, etc.; examples of saturated polycarboxylic acids include phthalic anhydride,
Isophthalic acid, terephthalic acid, succinic acid, adipic acid, etc. can be used, and as the polyhydric alcohol, for example, ethylene glycol, propylene glycol, diethylene glycol, etc. can be used. The unsaturated monomer that is component (C) in the present invention is
Copolymerized with the unsaturated polyester, and the above (A) and
Component (B) may be uniformly dissolved, and specifically, styrene, chlorostyrene, alkyl methacrylate, or a mixture thereof can be used. In the present invention, the blending ratio of the copolymer as component (A) is preferably in the range of 3 to 9% by weight. The reason for this is that if the blending amount is less than 3% by weight, it is difficult to sufficiently exhibit the low shrinkage effect;
This is because if it exceeds this, it may cause damage such as a decrease in the strength of the molded product. In order to cure the resin composition according to the present invention, a known curing agent such as benzoyl peroxide,
Methyl ethyl ketone peroxide or the like is used, and if necessary, a curing accelerator such as an organic metal salt such as cobalt octenoate, aromatic amines, β-diketones, etc. is used in combination. Next, examples of the present invention will be described. Note that parts in the examples mean parts by weight. Example 1 First, 90 parts of vinyl acetate, 10 parts of methyl methacrylate
A copolymer with a molecular weight of 40,000 was synthesized from this mixture and dissolved in styrene to obtain a resin liquid (1) with a solid content of 30%. Similarly, a copolymer with a molecular weight of 35,000 was synthesized from 70 parts of vinyl acetate and 30 parts of methyl methacrylate, and dissolved in styrene to obtain a resin liquid (2) with a solid content of 30%. Similarly, a copolymer was synthesized from 85 parts of vinyl acetate and 15 parts of ethyl acrylate, and dissolved in styrene to obtain a resin liquid (3) with a solid content of 30%. Additionally, an unsaturated polyester with an acid value of 25 was synthesized from 0.6 mol of fumaric acid, 0.4 mol of phthalic anhydride, and 1.1 mol of propylene glycol, and dissolved in styrene to obtain a resin liquid () with a solid content of 30%. Similarly, 0.4 mol of maleic anhydride, 0.6 mol of phthalic anhydride, 0.7 mol of propylene glycol, ethylene glycol
An unsaturated polyester with an acid value of 35 was synthesized from 0.4 mol and dissolved in styrene to obtain a resin liquid () with a solid content of 60%. Next, add the above resin liquid (1) or (2) or (3).
20 parts and 80 parts of the above resin solution () or (2) were mixed to obtain 100 parts of six types of resin compositions. All of these compositions did not become cloudy upon mixing and became transparent and uniformly miscible. Further, 1 part of benzoyl peroxide was added to 100 parts of these resin compositions, and the mixture was cured by heating at 120°C for 30 minutes to form a cast plate of 4 x 16 x 1 cm. The cured dimensional change rate and bending strength of these molded products were investigated. The results are shown in Table 1 below. Example 2 300 parts of sand, 100 parts of calcium carbonate, 3.0 parts of methyl ethyl ketone peroxide, 1.0 part of cobalt octenoate, and 0.2 parts of dimethylaniline were mixed with 100 parts of the six resin compositions of Example 1 to prepare a resin mortar. A specimen measuring 6 x 6 x 24 cm was molded at room temperature. The curing dimensional change rate and bending strength of these specimens were investigated. The results are shown in Table 2 below. Example 3 First, an unsaturated polyester having an acid value of 35 was synthesized from 1.0 mol of maleic anhydride and 1.05 mol of propylene glycol, and dissolved in styrene to obtain a resin liquid () with a solid content of 65%. Resin liquid (1) of Example 1 or
25 parts of (2) or (3) and the resin liquid (2) were mixed to obtain 100 parts of three types of resin compositions. Upon mixing, these compositions became transparent without producing cloudiness and were uniformly miscible. In addition, for 100 parts of these resin compositions, 200 parts of calcium carbonate and 100 parts of chopped glass fiber are added.
1 part, 4 parts of zinc stearate, and 1 part of t-butyl peroxybenzoate were blended and aged to obtain a molding compound. These molding compounds are heated to
Compression molding was performed at 180°C to obtain a molded product of 10 x 10 x 0.5 cm. These molded products have good surface smoothness.
Further, when the cured dimensional change rate and bending strength of these were investigated, the results were as shown in Table 3 below. Comparative example First, polyvinyl acetate with a molecular weight of 40,000 was synthesized from vinyl acetate, and dissolved in styrene to give a solid content of 30%.
A resin liquid (4) was obtained. 20 parts of resin liquid (4) and Example 1
100 parts of two types of resin compositions were obtained by mixing 80 parts of the resin liquid () or (2). For 100 parts of these resin compositions, 300 parts of sand, 100 parts of calcium carbonate,
Mix 3.0 parts of methyl ethyl ketone peroxide, 1.0 part of cobalt octenoate, and 0.2 parts of dimethylaniline to make a resin mortar, and make a 6 x 6 x 24 resin mortar at room temperature.
A specimen of cm was molded. When the cured dimensional change rate and bending strength of these specimens were investigated, the results were as shown in Table 4 below.

【table】

【table】

【table】

[Table] As shown in Tables 1 to 4 above, unsaturated polyester resin compositions according to the present invention (a to o in the table)
The molded product obtained from the same conventional composition (p, q in the table)
It can be seen that the cured dimensional change rate was significantly smaller than that of the molded product obtained from the molded product, and the molded product had excellent low shrinkage. In addition, the resin mortar (g to l in the table) obtained by adding calcium carbonate etc. to the unsaturated polyester resin composition according to the present invention has a higher level of improvement than the resin mortar obtained from the conventional same composition (p, q in the table). It can be seen that it is also excellent in terms of bending strength. Furthermore, as described above, the resin composition according to the present invention is one in which each component is uniformly miscible with each other and has excellent solution stability. Furthermore, since a liquid unsaturated monomer is used, room temperature molding and casting molding are possible. As detailed above, the present invention sufficiently suppresses shrinkage due to curing, is applicable to a wide range of unsaturated polyesters, has excellent solution stability, and improves reliability and workability when forming various molded products. It is possible to provide a low shrinkage unsaturated polyester resin composition having the above remarkable advantages.

Claims (1)

[Scope of Claims] 1 (A) 95-50% by weight of a copolymer of vinyl acetate and an alkyl methacrylate or alkyl acrylate, (B) an unsaturated polyester, (C ) an unsaturated monomer that can be copolymerized with an unsaturated polyester and is liquid at room temperature selected from styrene, chlorostyrene, and alkyl methacrylate; 1. A low-shrinkage unsaturated polyester resin composition characterized by being uniformly miscible with each other.