JPH03285947A - Unsaturated polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain an unsaturated polyester resin composition having small shrinkage during curing and excellent tinting, dimensional stability and surface characteristics, by blending an unsaturated polyester with a styrene-vinyl acetate block copolymer and styrene-diene block copolymer. CONSTITUTION:(A) 100 pts.wt. of an unsaturated polyester and a crosslinking agent (25-70 pts.wt. crosslinking agent) are blended with (B) styrene-vinyl acetate block copolymer having preferably <=50% vinyl acetate content and (C) an SBS-based or SIS-based styrene-diene block copolymer using polystyrene as a hard segment and polybutadiene or polyisoprene as a soft segment, a hydrogenated substance or a modified substance thereof in an amount to give 15-50 pts.wt. components B+C and the weight ratio of the component B/C of (20/80)-(80/20) and further mixed with a curing agent, a filler, a mold-release compound, a thickening agent, a fiber reinforcing material, etc., to give an unsaturated polyester resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an unsaturated polyester resin composition. More specifically, the present invention is an unsaturated polyester resin composition that exhibits little shrinkage during curing, has particularly good colorability, and has excellent dimensional accuracy and surface properties (surface smoothness, surface gloss, surface appearance, etc.). It is about things.

[Conventional technology]

Conventionally, unsaturated polyester resin molding materials (BMC, SM
Due to its excellent dimensional accuracy and moldability, C) is widely used in fields where dimensional accuracy is strict, such as the chassis of OA equipment.

In general, low shrinkage of unsaturated polyester resin molding materials is achieved by using polystyrene, polyethylene, styrene-vinyl acetate block copolymer, vinyl acetate resin, styrene-butadiene block copolymer, acrylic resin, cellulose acetate butyrate, saturated polyester This is achieved by using a thermoplastic polymer such as a resin, but the shrinkage rate and colorability of the molded article vary depending on the type and amount of the thermoplastic polymer used.

Polystyrene, polyethylene, etc. have good colorability and excellent surface appearance, but shrinkage during curing is at least 0.
．． 0.3%, and dimensional accuracy and surface smoothness tend to be poor.

On the other hand, if a saturated polyester resin or the like is used, the shrinkage rate during curing is small at -0,010 to +0.010, and the dimensional accuracy and surface smoothness are excellent, but color unevenness may occur and the result is not good. The actual situation was that good coloring properties could not be obtained and the surface appearance was poor.

[Problem to be solved by the invention]

In this way, by simply blending conventional thermoplastic polymers into unsaturated polyester molding materials, it is impossible to improve shrinkage during curing and obtain molded products with good colorability, excellent dimensional accuracy, and surface properties. could not.

In order to improve these drawbacks, attempts have been made to use two or more thermoplastic polymers in combination, such as a combination of polystyrene and polyethylene, but nothing good has yet been obtained.

[Means to solve the problem]

The present inventors have conducted extensive research to improve these drawbacks, and have found that unsaturated polyester resins include styrene-vinyl acetate block copolymers, styrene-diene block copolymers, and their hydrogenated or modified products (hereinafter referred to as , a styrene-diene block copolymer) in a specific ratio, it is possible to create an unsaturated polyester resin composition that exhibits little shrinkage during curing, has good colorability, and has excellent dimensional accuracy and surface properties. The present invention has been completed.

That is, the present invention comprises (b) styrene-vinyl acetate block copolymer and (e) in a range of 15 to 50 parts by weight based on 100 parts by weight of (a) unsaturated polyester and crosslinking agent.
Adding a styrene-diene block copolymer, (b)/
The present invention provides an unsaturated polyester resin composition in which the weight ratio of (c) is in the range of 20/80 to 80/20.

The present invention will be explained in more detail below.

a Bo1Esur The type of unsaturated polyester used in the present invention is not particularly limited, and it is a polycondensation product of polyhydric alcohol, unsaturated polybasic acid, and saturated polybasic acid, and is usually used as a molding material. Any suitable material can be used as long as it is used as a material. Furthermore, a vinyl ester resin and a diallyl phthalate resin may be blended as part of the unsaturated polyester.

Examples of polyhydric alcohols that form unsaturated polyesters include ethylene glycol, propylene glycol,
Examples include butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, bentanediol, hexanediol, neobentanediol, hydrogenated bisphenol A, bisphenol A, glycerin, and the like.

Examples of unsaturated polybasic acids include maleic anhydride, fumaric acid,
Citraconic acid, itaconic acid, etc., and saturated polybasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, het acid, succinic acid, adipic acid, sebacic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, endomethylene Examples include tetrahydrophthalic anhydride.

As for the crosslinking agent, any suitable crosslinking agent can be used as long as it has a polymerizable double bond that can be polymerized with the above-mentioned unsaturated polyester. Examples of such substances include styrene monomers, diallyl phthalate monomers,
Examples include diallyl phthalate prepolymer, methyl methacrylate, and triallyl in cyanurate. The amount used is 25 to 70 parts by weight, preferably 35 to 65 parts by weight, based on 100 parts by weight of unsaturated polyester and crosslinking agent.

In the present invention, a styrene-vinyl acetate block copolymer and a styrene-diene block copolymer are added to the above unsaturated polyester and crosslinking agent together with a curing agent and other compounding agents. However, the styrene-vinyl acetate block copolymer used preferably has a blending ratio of vinyl acetate of 50% or less.

As the C styrene-diene block copolymer, polystyrene was used as the hard segment and polybutadiene or polyisoprene was used as the soft segment.
It is a BS-based or SIS-based thermoplastic elastomer, or a hydrogenated product obtained by hydrogenating the above-mentioned SBS-based or SIS-based elastomer. As the SEBS thermoplastic elastomer or modified product, any of reactive saturated thermoplastic elastomers obtained by imparting reactivity to these with maleic anhydride or the like can be used.

Mixtures of these can also be used.

The bonding mode of the styrene-diene block copolymer is roughly divided into a type in which a polystyrene part and a diene polymer part take a linear bonding mode, and a radial type in which the diene polymer parts are coupled to each other. Can be used.

The ratio of styrene part and diene part is styrene is 50% of the total.
It is preferably 10% or more.

The amount of the styrene-vinyl acetate block copolymer (b) and the styrene-diene block copolymer (c) is determined based on the total of 100 parts by weight of the unsaturated polyester and the crosslinking agent. The total amount of polymerization and styrene-dienepro-y-copolymer is 15 to 50
If the amount is less than 15 parts by weight, shrinkage during curing will be large, and if it is more than 50 parts by weight, the colorability will be impaired, and the good colorability that is the objective of the present invention will not be achieved. A non-shrinkage resin composition is not possible.

Also, the weight ratio (b) of the styrene-vinyl acetate block copolymer (b) and the styrene-diene block copolymer (C)
/c) is preferably in the range of 20/80 to 80/20; if it is less than 20/80, shrinkage during curing will be large and the colorability will not be good; In some cases, although the colorability is good, the shrinkage during curing is large and the effects of the present invention cannot be achieved.

Styrene-vinyl acetate block copolymers and styrene-diene block copolymers are generally convenient to handle if they are dissolved or swollen in the crosslinking agent such as styrene in advance; Alternatively, it can be used without swelling.

Other compounding agents include curing agents, fillers, mold release agents, thickeners,
There are fiber reinforcement materials, pigments, etc.

The curing agent is a peroxide, and an appropriate one can be used.1 For example, t-butyl peroxyoctoate, benzoyl peroxide, 1.1 dibutyl peroxy3
, 3.5 trimethylcyclohexane, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate, dicumyl peroxide, di-t-butyl peroxide, and the like.

Inorganic powders such as silica, alumina, mica, aluminum hydroxide, calcium carbonate, gypsum, barium sulfate, clay, and talc can be used as fillers.

As the mold release agent, for example, stearic acid, oleic acid, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, stearamide, oleic acid amide, carbana wax, silicone oil, synthetic wax, etc. are used in appropriate proportions. It can be used in

Examples of thickeners include metal compounds such as magnesium oxide, magnesium hydroxide, calcium hydroxide, and calcium oxide, and incyanate compounds.

A thickener does not necessarily have to be used.

Chopped strand glass cut into fiber lengths of about 1.5 to 25 mm is used as the fiber reinforcing agent. Further, organic and inorganic fibers such as pulp fiber, Tetoron fiber, vinylon fiber, carbon fiber, aramid fiber, and wollastonite can be used.

Regarding the unsaturated polyester resin composition of the present invention constituted by the above components, there are no particular limitations on the manufacturing method thereof.

Pigments or dyes can be blended into these unsaturated polyester resin compositions by conventional methods, and desired molded products can be obtained by compression molding, transfer molding, or injection molding. There is little shrinkage during curing, and the molded product exhibits good colorability without uneven coloring, and is excellent in dimensional accuracy, surface appearance, surface properties, etc.

[Examples and comparative examples]

Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples. Of course, this invention is not limited to the following examples unless it goes beyond its gist.

12 Uni The respective ingredients were kneaded using a double-arm kneader to obtain an unsaturated polyester resin composition having the composition shown in Table 1. The unsaturated polyester resins used here are the following four types, all of which have a styrene monomer content of 30.
%Met.

A: Fumar M 100 mol, propylene glycol 8
0 mol, hydrogenated bisphenol A 20 mol; B: fumaric acid 80 mol, isophthalic acid 20 mol, propylene glycol 100 mol; C: maleic anhydride 1
00 mol, propylene glycol 100 mol; D: fumaric acid 70 mol, orthophthalic acid 30 mol, propylene glycol 100 mol.

In addition, carbon black was used as a pigment to examine colorability.

This composition was tested and evaluated for molding shrinkage and surface properties. The testing and evaluation methods are as follows.

(1) Mold shrinkage rate A shrinkable disk specified in JIS K-6911 was compression molded at a molding temperature of 150°C, a molding pressure of 100 kg/am2, and a molding time of 3 minutes, and the molding shrinkage rate was determined based on JIS K-6911. was calculated.

(2) Surface properties (2)-1 Evaluation using a flat plate Molding temperature: 150°C, molding pressure: 100 kg/am2,
300x220xt 3 by compression molding in 3 minutes molding time
A flat plate of m- was molded, and colorability, leveling, and gloss were visually evaluated.

(2)-2 Evaluation using a test box As shown in Figures 1 and 2, a test box (3
60 x 120
Injection molding was performed using an injection molding machine N-300 manufactured by Japan Steel Works at 60°C, injection pressure 300 kII/am'', and molding time 2 minutes, and colorability, leveling, and gloss were visually evaluated.

The results of these measurements and evaluations are shown in Table 1.

As shown in Table 1, the molding shrinkage rate was 0.00% or less in all of the Examples, and excellent non-shrinkage properties during curing. In addition, a molded product with good colorability and excellent dimensional accuracy and surface properties was obtained.

In the same manner as in Examples 1 to 6, unsaturated polyester resin compositions having the formulations shown in Table 2 were produced, molded articles were molded in the same manner, the properties were tested and evaluated, and the results were Shown in Table 2.

As is clear from Table 2, in the case of unsaturated polyester compositions to which styrene-vinyl acetate block copolymer and styrene-diene block copolymer are not added, there is no shrinkage during curing as shown in the examples. No results were obtained on the properties of color, coloration, surface appearance, surface properties, or dimensional accuracy.

Even if the composition contains a styrene-vinyl acetate block copolymer and a styrene-diene block copolymer, good molded products may not be obtained if the blending amount is outside the above specified range. I couldn't.

〔Effect of the invention〕

The unsaturated polyester resin composition according to the present invention, which is characterized by the addition of a styrene-vinyl acetate block copolymer and a styrene-diene block copolymer, has non-shrinkage properties during curing that could not be obtained with conventional techniques. Due to its excellent surface appearance, dimensional accuracy, and excellent surface properties, it can be widely used as an unsaturated polyester resin composition useful in the electrical, electronic, and automobile industries, etc. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the test box used in the test, and FIG. 2 is a sectional view taken along line A-A'' in FIG.

Claims (1)

[Claims] (b) styrene-vinyl acetate block copolymer and (c) styrene-diene block copolymer, hydrogenated product thereof in a range of 15 to 50 parts by weight based on 100 parts by weight of (a) unsaturated polyester and crosslinking agent. or by adding a modified product (b
) and (c) weight ratio (b)/(c) is 20/80 to 80
/20.