JPH04370131A - Styrene resin composition - Google Patents

Abstract

PURPOSE:To obtain a styrene resin composition having well-balanced moldability, heat-resistance, strength and rigidity by compounding a styrene resin with a hydrogenated terpene resin. CONSTITUTION:The objective styrene resin composition is produced by mixing (A) 100 pts.wt. of a styrene resin having a molecular weight of 150,000-500,000 (preferably 180,000-450,000) with (B) 0.5-30 pts.wt. (preferably 0.5-30 pts.wt.) of a hydrogenated terpene resin produced by copolymerizing terpene with an aromatic hydrocarbon (preferably styrene) and hydrogenating the copolymer and having a hydrogenation ratio of >=10% (preferably >=20%) (e.g. Clearon P or Clearon M; product of Yasuhara Chemical Co., Ltd.). The mixing of the components is carried out either by dissolving the component B in the monomer mixture before the polymerization of the component A and polymerizing the monomer or by mixing the components A and B and kneading the mixture with an extruder a molding machine, etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrenic resin containing a hydrogenated terpene resin. More specifically, the present invention provides a styrenic resin composition with an excellent balance of heat resistance, moldability, strength, and rigidity.

0002

[Prior Art and Problems] Styrenic resin has long been known as a resin with excellent transparency, moldability, and rigidity.
It has been widely used as a molding material for household goods, electrical appliances, etc. Recently, due to the rising cost of raw materials, there is a trend to replace other high-grade resins with relatively inexpensive resins, and the demand for styrenic resins is on the rise. Along with this, there is an increasing demand for improvements in the strength and moldability of styrenic resins in order to expand the field of use and increase product productivity.

It is a well-known fact that in order to obtain a styrenic resin with high strength, it is sufficient to increase the average molecular weight. However, increasing the average molecular weight inevitably reduces moldability. Furthermore, it is a known method to use a plasticizer to supplement moldability, but adding a plasticizer reduces heat resistance, rigidity, and strength. In some fields, high-speed molding is desired in order to increase product productivity, and this cannot be achieved simply by increasing the molecular weight and improving strength and moldability through the use of plasticizers.

[0004] Furthermore, when using styrenic resins to which a plasticizer, such as white mineral oil, is added, the plasticizer bleeds out during molding.
It is a well-known fact that a sweating phenomenon occurs, leading to a decrease in productivity and quality of molded products.

[0005]

[Problems to be Solved] In view of the current situation, the present inventors have made extensive studies and have found that by blending terpene-based hydrogenated resin with styrene-based resin, moldability, heat resistance, strength, and rigidity can be improved. It was discovered that a styrenic resin composition with excellent elasticity can be obtained, and the present invention was completed. That is, the present invention provides a styrene resin comprising a styrene resin and a terpene hydrogenated resin.

[0006] The styrene resin referred to in the present invention refers to a resin obtained by polymerizing styrene monomers such as styrene, p-methylstyrene, pt-butylstyrene, α-methylstyrene alone or in a mixture, and a styrene monomer. styrene copolymer resin with a monomer copolymerizable with the polymer, such as acrylonitrile, butyl acrylate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylic acid, methacrylic acid, maleic anhydride, etc. These include the above-mentioned styrene-based resins and styrene-based copolymer resins containing rubber-like elastic bodies as dispersed particles, and resins obtained by mixing the above-mentioned styrene-based resins, styrene-based copolymer resins, and rubber-like elastic bodies. The molecular weight of the styrene resin is not particularly limited, but is 15
0000-500000 preferably 180000-45
A styrenic resin in the range of 0,000 is preferably used. If the molecular weight is lower than this range, the strength improvement effect will be small even if terpene hydrogenated resin is blended, and styrenic resins with a molecular weight higher than this range will have poor moldability, and the production of styrenic resin itself will be poor. This is undesirable as it reduces performance.

[0007] Terpene-based hydrogenated resin is a resin obtained by copolymerizing terpene and aromatic hydrocarbon and hydrogenating this copolymer. Styrene is preferably used as the aromatic hydrocarbon. Although there is no particular restriction on the hydrogenation rate, hydrogenation of 10% or more, preferably 20% or more is preferred. If it is less than 10%, the color tone of the styrenic resin deteriorates when exposed to high temperatures, which is not preferable.

[0008] As the terpene-based hydrogenated resin, for example, Clearon P and Clearon M manufactured by Yasuhara Chemical Co., Ltd. can be used. The terpene hydrogenated resin can be added by dissolving it in a styrene monomer or a monomer mixture that can be copolymerized with a styrene monomer, or by adding it to a styrene polymer or a styrene copolymer. During the polymerization process, the terpene-based hydrogenated resin is melted,
Alternatively, methods such as adding the terpene-based hydrogenated resin by dissolving it in a solvent, or adding the terpene-based hydrogenated resin before or after polymerization is completed and unreacted styrene monomers and the like are removed can be used. It is also possible to mix the styrene resin and the hydrogenated terpene resin and knead them using an extruder or molding machine.

[0009] The ratio of styrene resin and terpene resin is 0 terpene resin per 100 parts by weight of styrene resin.
．． 5 to 30 parts by weight is preferred. Furthermore, preferably 0.5 parts of terpene resin per 100 parts by weight of styrene resin.
~30 parts by weight. The styrenic resin of the present invention contains various additives frequently used in conventional styrenic resins, such as stearic acid, behenic acid, metal esters thereof (calcium, magnesium, zinc, etc.), and ethylene bisstearamide. It can also be an antioxidant,
Coloring agents, antistatic agents, etc. may also be added.

[0010] A more detailed explanation will be given below with reference to Examples. However, the present invention is not limited to these Examples in any way.

[0011]

【Example】

(Styrenic polymer-1) In a 10L autoclave equipped with a stirrer, 5 kg of styrene, 0.2 kg of ethylbenzene,
1,1 bis(t-butylperoxy)cyclohexane 1
．． After polymerizing at 110°C for 3 hours, 130°C for 3 hours, and 150°C for 2 hours, unreacted styrene,
Ethylbenzene is recovered to obtain styrenic polymer-1.

Weight average molecular weight measured by GPC is 346
,000. (Styrenic polymer-2) In a 10L autoclave equipped with a stirrer, 5 kg of styrene, 0.5 kg of ethylbenzene,
1,1 bis(t-butylperoxy)cyclohexane 1
g, and heated at 120℃ for 2 hours and at 140℃ for 2 hours, 1
After polymerization at 50° C. for 2 hours, unreacted styrene and ethylbenzene are recovered using an extruder to obtain styrenic polymer-2.

Weight average molecular weight measured by GPC is 297
,000.

[0014]

[Example-1 to Example-3] Styrenic polymer-1
2.4 terpene-based hydrogenated resin per 100 parts by weight
, 6 parts by weight are mixed and granulated using a 20 mm twin-screw extruder to obtain a styrene resin. The physical properties are shown in Table 1. The terpene-based hydrogenated resin used was Clearon P manufactured by Yasuhara Chemical Co., Ltd.

[0015]

[Example 4 to Example 6] Styrenic resins were obtained in the same manner as in Example 1 except that styrene polymer 2 was used. The physical properties are shown in Table 1.

[0016]

[Comparative Examples 1 to 3] Styrenic resins were obtained in the same manner as in Example 1, except that mineral oil was used instead of the terpene hydrogenated resin. The physical properties are shown in Table 1.

[0017]

[Comparative Examples 4 to 6] Styrenic resins were obtained in the same manner as in Example 4, except that mineral oil was used instead of the terpene hydrogenated resin. The physical properties are shown in Table 1.

[0018]

[Comparative Example-7, Comparative Example-8] Table 1 shows the physical properties of Styrenic Polymer-1 and Styrenic Polymer-2. The styrenic resin composition of the present invention has no change in heat resistance and rigidity, and, as shown in FIG. 1, has a better fluidity-strength balance than the styrene resin containing mineral oil.

[0019]

[Table 1]

[0020]

[Effects of the Invention] The styrenic resin composition of the present invention has a significantly better balance of moldability, heat resistance, strength, and rigidity than styrene resin compositions containing plasticizers that have been commonly used in the past.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between fluidity and strength of the styrenic resin composition of the present invention and conventional styrenic resins.

Claims (1)

[Claims] [Claim 1] A styrenic resin composition comprising a styrene resin and a terpene hydrogenated resin.