JPH0140059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an unsaturated polyester having a low shrinkage rate upon curing, and more particularly to a one-component low shrinkage unsaturated polyester resin composition.

Unsaturated polyester resin has 5 to 10
It is accompanied by a volumetric contraction of about %. Such curing shrinkage is the cause of many defects in resin mortar and resin concrete filled with glass fiber reinforced molding materials or sand, such as impeding the surface smoothness of the molded product due to embossment of the reinforcing material, and causing warping and cracking. Become.

By the way, as a method to reduce such curing shrinkage of unsaturated polyester resin, polyethylene,
Addition of thermoplastic resins such as acrylic resins and saturated polyesters is generally employed. As a low-shrinkage unsaturated polyester resin material containing acrylic resin, "Paraplex" manufactured by Rohm and Haas is known, and this molding material has a very low molding shrinkage rate and improves the surface smoothness of molded products. Are better. However, such materials have poor solution stability, and unless they are mixed and stirred immediately before use, the thermoplastic resin, which is the low-shrinkage imparting agent, will separate and lose the low-shrinkage effect. Furthermore, in order to obtain a sufficient low-shrinkage effect, a considerable amount of a low-shrinkage imparting agent is required, which causes problems such as a decrease in the strength of the molded product.

For this reason, the present inventors have conducted extensive research to overcome the above drawbacks, and as a result, they have used an extremely low molecular weight acrylic resin (component A) as a low-shrinkage agent, and have also used an unsaturated polycarboxylic acid. An unsaturated monomer (component C) that can be copolymerized with the unsaturated polyester (component B) is blended with an unsaturated polyester (component B) having a defined molar ratio of
By using these together, we have discovered a low-shrinkage unsaturated polyester resin composition in which each component is uniformly compatible and has excellent solution stability.

That is, the present invention comprises: (A) polymethyl methacrylate having a degree of polymerization of 100 to 200;
Or polymerization degree consisting of methyl methacrylate and acrylic acid alkyl ester or methacrylic acid alkyl ester other than methyl methacrylate
100 to 200 copolymers of 4 to 9% by weight each; (B) an unsaturated polyester having a molar ratio of saturated polycarboxylic acid to unsaturated polycarboxylic acid of 1.0 or less; and (C) copolymer with unsaturated polyester. It is characterized in that it consists of a polymerizable unsaturated monomer, and the above (A), (B), and (C) are homogeneously dissolved.

Component (A) in the present invention is a homopolymer or copolymer containing methyl methacrylate as a monomer. Examples of acrylic acid alkyl esters to be copolymerized with this monomer include ethyl acrylate, and examples of methacrylic acid alkyl esters other than methyl methacrylate include butyl methacrylate. The reason why the degree of polymerization of the polymethyl methacrylate and copolymer of component (A) is limited to the above range is that if the degree of polymerization is less than 100, the shrinkage effect cannot be sufficiently exerted;
This is because when it exceeds 200, the compatibility with each component decreases.

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 reason for limiting the molar ratio of the saturated polycarboxylic acid to the unsaturated polycarboxylic acid in these unsaturated polyesters is that if the molar ratio exceeds 1.0, the compatibility with component (A) will decrease. be.
In addition, the molecular weight of unsaturated polyester is approximately 10,000 ~
A range of 20000 is recommended.

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 component (A) is preferably in the range of 4 to 9% by weight. The reason for this is
This is because if the amount is less than 4% by weight, it is difficult to sufficiently exhibit the low shrinkage effect, whereas if it exceeds 9% by weight, there is a risk of negative effects 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, the present invention will be explained by examples. Note that parts in the examples mean parts by weight.

Example 1 First, polymethyl methacrylate having a molecular weight of 15,000 was synthesized from methyl methacrylate and dissolved in styrene to obtain a resin liquid () with a solid content of 30%. Synthesize an unsaturated polyester with a molecular weight of 1500 from 0.6 mol of fumaric acid, 0.4 mol of phthalic anhydride, and 1.1 mol of propylene glycol, and dissolve it in styrene to obtain a solid content of 60%.
A resin liquid () was obtained. Next, 20 parts of the above resin liquid ( ) and 80 parts of the above resin liquid ( ) were mixed to obtain 100 parts of a resin composition.

The resulting composition did not become cloudy upon mixing and became transparent, and no separation into layers was observed even after it was left at a temperature of 30° C. for one month. Further, 1 part of benzoyl peroxide was added to 100 parts of this composition, and the mixture was cured by heating at 120° C. for 30 minutes to form a cast plate. This molded product is a slightly cloudy, smooth plate with a cured dimensional change rate of +0.05%.

Furthermore, calcium carbonate is added to 100 parts of the above resin composition.
100 parts of river sand, 300 parts of river sand, 1.5 parts of methyl ethyl ketone peroxide, 1.0 part of cobalt octenoate, and 0.1 part of dimethylaniline were mixed to make a resin mortar.
The specimen was molded at room temperature. The cured dimensional change rate of this specimen was +0.03%, and the bending strength was 290 Kg/cm ² .

Example 2 First, a copolymer with a molecular weight of 20,000 was synthesized from 0.85 mol of methyl methacrylate and ethyl methacrylate,
A resin liquid (2) with a solid content of 30% was obtained by dissolving in styrene. An unsaturated polyester with a molecular weight of 2000 was synthesized from 1.0 mol of maleic anhydride, 0.7 mol of propylene glycol, and 0.4 mol of ethylene glycol, and dissolved in styrene to obtain a resin liquid () with a solid content of 65%. Next, 25 parts of the above resin liquid () and 75 parts of the above resin liquid (2) were mixed to obtain 100 parts of a resin composition.

The resulting composition did not become cloudy upon mixing and was transparent, and no separation into layers was observed even after it was left at a temperature of 30° C. for one month. Calcium carbonate per 100 parts of this composition
200 parts chopped glass fiber 100 parts, zinc stearate 4 parts t-butyl peroxybenzoate 1 part were mixed and aged to obtain a molding compound. This was compression molded at a temperature of 180°C. This molded article had good surface smoothness and a cured dimensional change of -0.01%.

Comparative Example 1 First, 0.4 mol of maleic anhydride 0.6 mol of phthalic anhydride
Synthesize an unsaturated polyester with a molecular weight of 2000 from 0.7 moles of propylene glycol and 0.4 moles of ethylene glycol, and dissolve it in styrene to obtain a solid content of 60%.
A resin liquid () was obtained. Next, the resin liquid ()
Mix 20 parts and 80 parts of resin liquid () to make a resin composition.
Got 100 copies. This composition became slightly cloudy upon mixing, and was separated into layers by standing at a temperature of 30° C. for 3 days. Add 1 part of benzoyl peroxide to 100 parts of this composition and heat at 120°C.
A cast plate was formed by heating and curing for 30 minutes. The cured dimensional change rate of this molded article was -2.0%.

Comparative Example 2 First, from 0.85 mol of methyl acrylate, 0.125 mol of ethyl acrylate, and 0.025 mol of acrylic acid, the molecular weight
A copolymer of 150,000 was synthesized and dissolved in styrene to obtain a resin liquid () with a solid content of 30%. Next, 25 parts of this resin liquid ( ) and 75 parts of the resin liquid ( ) were mixed to obtain 100 parts of a resin composition. This composition became cloudy upon mixing, and was separated into layers by standing at a temperature of 30° C. for one day. In addition, this resin composition
When a molding compound was obtained from 100 parts using the same formulation as in Example 2 and compression molded, the cured dimensional change rate of the molded product was -0.8%.

As detailed above, according to the present invention, it is possible to provide a low-shrinkage unsaturated polyester resin composition that has remarkable effects such as excellent low-shrinkage property and solution stability, and enables molding of various molded products with high reliability. It is something.

Claims (1)

[Scope of Claims] 1 (A) Polymethyl methacrylate with a polymerization degree of 100 to 200, or a copolymer with a polymerization degree of 100 to 200 consisting of methyl methacrylate and an acrylic acid alkyl ester or a methacrylic acid alkyl ester other than methyl methacrylate. 4 to 9% by weight of each polymer; (B) an unsaturated polyester having a molar ratio of saturated polycarboxylic acid to unsaturated polycarboxylic acid of 1.0 or less; and (C) an unsaturated polyester that can be copolymerized with the unsaturated polyester. 1. A low-shrinkage unsaturated polyester resin composition comprising a monomer, wherein (A), (B), and (C) are homogeneously dissolved.