JP2003292706A - Stabilized thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermoplastic resin composition having sufficient stability even under high-temperature processing conditions. <P>SOLUTION: This thermoplastic resin composition comprises a synthetic resin stabilizer whose added amount is in a fixed range based on a fixed weight of a styrene-based resin and which is added with a lactone-based additive having a specific structure whose added amount is in a fixed range. The thermoplastic resin composition is obtained by adding the synthetic resin stabilizer having the specific structure and whose added amount is in the fixed range and the lactone based additive having the specific structure, and whose added amount is in the fixed range to a fixed weight of the resin composition containing a styrene resin having a content in a fixed range and a polyphenylene ether resin having a content in a fixed range. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermoplastic resin composition having sufficient stability even under high-temperature processing conditions.

[0002]

2. Description of the Related Art The heat resistance of polystyrene resin is
It is not so expensive, but it has excellent fluidity and processability and is used in many applications. In addition, at normal processing temperature, the processing temperature is not so high. Therefore, by using the conventionally known phenol-based stabilizer or phosphorus-based stabilizer, the processing stability is sufficiently improved in practical use. ing. However, since the polystyrene resin has not so high heat resistance, its use is limited. On the other hand, a polyphenylene ether (hereinafter sometimes referred to as “PPE”) resin is a resin having excellent mechanical strength and heat resistance, but as the heat resistance increases, the fluidity deteriorates, Often the temperature has to be increased. Therefore, a resin composition composed of the above-mentioned polystyrene resin and polyphenylene ether resin has been proposed. Since the processing temperature of the resin composition comprising the polystyrene resin and the polyphenylene ether resin is significantly higher than the processing temperature of the polystyrene resin, the stability of the polystyrene resin at this processing temperature is still insufficient. Is.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic resin composition having sufficient stability even under high temperature processing conditions.

[0004]

Means for Solving the Problem The present inventor has found that a stabilizer for a synthetic resin having a specific structure and having a specific amount of the styrene-based resin added in a certain range with respect to a constant weight of the styrene-based resin has a constant addition amount. And a thermoplastic resin composition to which a lactone-based additive having a specific structure is added, and a styrene-based resin whose content is in a certain range, and a polyphenylene whose content is in a certain range. With respect to a constant weight of a resin composition containing an ether-based resin, the addition amount is in a constant range, a stabilizer for synthetic resin having a specific structure, and the addition amount is in a constant range, a specific structure It was found that a thermoplastic resin composition to which a lactone-based additive having the above is added can solve the above problems, and has completed the present invention.

That is, the present invention is based on 100 parts by weight of (A) polystyrene resin, 0.05 to 2 parts by weight of a stabilizer for synthetic resin represented by the following general formula (I), and the following general formula ( II) Lactone-based additive represented by 0.02
˜2 parts by weight is added to the thermoplastic resin composition. (In the formula, R ₁ represents an alkyl group having 1 to 3 carbon atoms) (In the above formula, R ₂ , R ₃ and R ₄ each independently represent a hydrocarbon group or a substituted hydrocarbon group, and R ₂ , R ₃ and R ₄
Two or more of them may combine with each other to form a saturated or unsaturated hydrocarbon ring. )

Further, the present invention is based on 100 parts by weight of a resin composition containing (A) a polystyrene resin of 5 to 95% by weight and (B) a polyphenylene ether resin of 5 to 95% by weight. 0.05 to 2 parts by weight of the stabilizer for synthetic resin represented by the formula (I) and the above general formula (I
The present invention relates to a thermoplastic resin composition to which 0.02 to 2 parts by weight of the lactone-based additive represented by I) is added.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polystyrene-based resin (A) used in the present invention is a known polystyrene-based resin, and a repeating structural unit derived from an aromatic vinyl compound represented by the following general formula is used as a polymer thereof. Those having at least 25% by weight or more are preferable. (In the formula, R ₇ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, Z represents a substituent which is a halogen atom or an alkyl group having 1 to 4 carbon atoms, and p represents an integer of 0 to 5. .)

Examples of such styrenic polymers include styrene and its derivatives such as p-methylstyrene and α-
Examples thereof include homopolymers and copolymers of methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene and the like. Further, a rubber-modified high impact polystyrene (HIP) containing 70 to 99% by weight of the above aromatic vinyl compound and 1 to 30% by weight of diene rubber.
S) can be used.

As the diene rubber which constitutes HIPS,
Examples thereof include homopolymers of conjugated diene compounds such as butadiene, isoprene, and chloroprene, copolymers of conjugated diene compounds with unsaturated nitrile compounds or aromatic vinyl compounds, and natural rubber. These may be used alone or in combination. More than one species can be used. Particularly, polybutadiene and butadiene-styrene copolymer are preferable. HIPS is obtained by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or a combination thereof.

The stabilizer for synthetic resin represented by the general formula (I) used in the present invention is a phenolic compound, and is 8,9-bis (2-hydroxy-1,1-dimethylethyl)- 2,4,8,10-Tetraoxaspiro {5.5} undecane and 3- (3-alkyl-5-t-
It can be produced by a conventional transesterification reaction with butyl-4-hydroxyphenyl) propionic acid or an acid halide thereof, an acid anhydride thereof or a lower alkyl ester thereof.

In the stabilizer for synthetic resin represented by the general formula (I) used in the present invention, the substituent R1 is an alkyl group having 1 to 3 carbon atoms.

The lactone type additive used in the present invention is
It is a compound represented by the following general formula (II) and having a lactone structure. (In the formula below, R ₂ , R ₃ and R ₄ each independently represent a hydrocarbon group or a substituted hydrocarbon group, and R ₂ , R ₃ and R ₄
Two or more of them may combine with each other to form a saturated or unsaturated hydrocarbon ring. )

Each of R ₂ , R ₃ and R ₄ is a hydrocarbon group or a substituted hydrocarbon group. Specific examples of the hydrocarbon group include an alkyl group and an aryl group, and these hydrocarbon groups are It may be substituted with a substituent containing halogen, oxygen or nitrogen. As an alkyl group,
Methyl, ethyl, i-propyl, n-, i- or t
A butyl group can be mentioned, and a phenyl group can be mentioned as an aryl group. Two or more of R ₂ , R ₃ and R ₄ may combine with each other to form a saturated or unsaturated hydrocarbon ring. Preferably, any one of R _{2 to} R ₄ is an aryl group and any other two form a ring.

Specifically, it is represented by the following formula (III). In the above formula, R ₅ and R ₆ are alkyl groups having 1 to 8 carbon atoms, and m and n are integers of 1 to 3. Examples of the alkyl group for R ₅ include a methyl group, an ethyl group, a propyl group, a t-, i- or n-butyl group, a hexyl group, an octyl group, and a t-pentyl group, preferably having 1 to 10 carbon atoms. 3 is an alkyl group, and a methyl group is particularly preferable. Examples of the alkyl group for R ₆ include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a t-butyl group, and a t-pentyl group, and a branched chain having 3 to 5 carbon atoms is particularly preferable. Alkyl groups, especially butyl groups are preferred. Further, m and n are preferably 2.

As the compound having this lactone structure,
Specifically, 5,7-di-t-butyl-3- (3,4-
Dimethylphenyl) -3H-benzofuran-2-one,
5,7-di-t-butyl-3- (3,5-dimethylphenyl) -H-benzofuran-2-one, 5,7-di-t
-Butyl-3- (3,4,5-trimethylphenyl)-
3H-benzofuran-2-one, 5,6,7-di-t-
Butyl-3- (3,4-dimethylphenyl) -3H-benzofuran-2-one, 5,7-di-t-butyl-3-
(4-Methylphenyl) -3H-benzofuran-2-one, 5-t-butyl-3- (3,4-dimethylphenyl) -3H-benzofuran-2-one, 5,7-di-t.
-Butyl-3- (3,4-dimethylphenyl) -3H-
Benzofuran-2-one, 5,7-dimethyl-3-
(3,4-Dimethylphenyl) -3H-benzofuran-
2-one, 5,7-dimethyl-3- (3,5-di-t-
Butylphenyl) -3H-benzofuran-2-one,
5,7-di-t-butyl-3- (3,5-di-t-butylphenyl) -3H-benzofuran-2-one, 5,7
-Di-t-pentyl-3- (3,5-dimethylphenyl) -3H-benzofuran-2-one, 5,7-di-t
-Pentyl-3- (3,5-dipentylphenyl) -3
H-benzofuran-2-one, 5,7-di-t-butyl-3- (3,4-dioctylphenyl) -3H-benzofuran-2-one and the like can be mentioned. In particular, the following formula (Formula 1)
5,7-di-t-butyl-3- (3,4-dimethylphenyl) -3H-benzofuran-2-one represented by (Chemical formula 1)

The amount of the stabilizer for synthetic resin represented by the general formula (I) used in the present invention is 0.05 to 2 parts by weight with respect to 100 parts by weight of the polystyrene resin (A). It is preferably 0.1 to 1 part by weight. If it is too small, the effect of improving heat resistance may be poor, and if it is too large, problems may occur during molding due to evaporation of additives and the like.

The amount of the lactone-based additive represented by the general formula (II) used in the present invention is 0.02 to 2 parts by weight, preferably 100 parts by weight of the polystyrene-based resin (A). Is 0.08 to 1 part by weight. If it is too small, the effect of improving heat resistance may be poor, and if it is too large, problems may occur during molding due to evaporation of additives and the like.

The polyphenylene ether (PPE) resin (B) used in the thermoplastic resin composition of the present invention is a known one, and is, for example, a general term for polymers represented by the following general formula, The polymers shown may be a single kind or a copolymer in which two or more kinds are combined. (In the formula, R ₈ , R ₉ , R ₁₀ and R ₁₁ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or at least two carbon atoms between the halogen atom and the phenyl ring. Represents a monovalent substituent selected from haloalkyl groups or haloalkoxy groups having no tertiary α-carbon, and n is an integer representing the degree of polymerization.)

In a preferred embodiment in the above formula, R ₈ and R ₉ are alkyl groups having 1 to 4 carbon atoms, and R ₁₀ and R _{11 are}
Is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
For example, poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6-diethyl-1,4-phenylene) ether, poly (2-methyl-6-ethyl-1,4-phenylene) ether , Poly (2-methyl-6-propyl-1,4-
Phenylene) ether, poly (2,6-dipropyl-1,4)
-Phenylene) ether, poly (2-ethyl-6-propyl-1,4-phenylene) ether and the like. Further, as the PPE copolymer, an alkyl trisubstituted phenol, for example, 2, in the above polyphenylene ether repeating unit,
A copolymer containing a part of 3,6-trimethylphenol can be mentioned. Further, it may be a copolymer obtained by grafting a styrene compound on these PPE. The styrene compound-grafted polyphenylene ether is a copolymer obtained by graft-polymerizing styrene compounds such as styrene, α-methylstyrene, vinyltoluene, and chlorostyrene as the above PPE.

An impact resistance improver may be added to the thermoplastic resin composition of the present invention. As an impact resistance improving material,
A styrene elastomer or polyolefin is used. Here, a known styrene elastomer can be used. For example, one or more styrene-butadiene block copolymers each having one or more polystyrene and polybutadiene segments, one or more styrene-isoprene copolymers each having one or more polystyrene and polyisoprene segments, and one or more polystyrene and isoprene-butadiene copolymers, respectively. A block copolymer having, or a block copolymer in which unsaturated portions of these isoprene part and butadiene part are selectively hydrogenated,
It is obtained by graft-polymerizing styrene onto a polyolefin elastomer obtained by copolymerizing ethylene, propylene, butene and diene components.

The length of the molecular chain of the polystyrene segment in these styrene elastomers is preferably 10,000 or more in terms of weight average molecular weight. If the polystyrene segment is too short, the compatibility with the PPE-based resin composition is reduced, and layered peeling may occur during injection molding, or sufficient impact resistance cannot be obtained, which is not preferable. Examples of the polyolefin include polyethylene, polypropylene, polybutene, polypentene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, chlorinated polyethylene, ethylene-propylene rubber (EPR), ethylene-propylene-.
Examples thereof include diene rubber (EPDM). Among them, preferred impact modifiers are styrene block copolymers in which unsaturated portions of isoprene and butadiene are selectively hydrogenated and polyolefin elastomers obtained by copolymerizing ethylene, propylene, butene and diene components. Graft-polymerized styrene.

When an impact resistance improver is added for the purpose of improving impact strength, polystyrene resin (A) is 5 to 95% by weight and polyphenylene ether resin (B) is 5 to 95%.
5 to 100 parts by weight of the resin composition containing
20 parts by weight is preferred.

The thermoplastic resin composition of the present invention comprises a stabilizer for synthetic resin represented by the general formula (I), a lactone-based additive represented by the following general formula (II), and optional additives. It is obtained by mixing the components in a predetermined ratio and melt-kneading. A twin-screw kneading extruder or a multi-screw kneader is preferable because PPE has high melt viscosity. Therefore, it is effective to control the kneading conditions at the time of melt kneading and knead at the lowest possible temperature. Specifically, it is preferable to use the one having a small molecular weight of each component within a range in which the shear rate is kept low, the cylinder temperature of the kneading machine is lowered to promote heat removal, and the mechanical strength is not significantly impaired. It is also effective to remove low molecular weight components generated by decomposition or the like with a vacuum vent. In addition to the synthetic resin stabilizer represented by the general formula (I) and the lactone-based additive represented by the following general formula (II), a commercially available stabilizer may be added.

Further, in the thermoplastic resin composition of the present invention,
If necessary, various known additives such as flame retardants, flame retardant aids, stabilizers, antioxidants, light stabilizers, lubricants, plasticizers,
An antistatic agent, a release agent, a coloring agent, an inorganic filler, and other thermoplastic resins can be blended.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
The following compounds were used in the examples. PS : polystyrene, Sumibright E183K (trademark: manufactured by Sumitomo Chemical Co., Ltd.), which corresponds to the component (A) of the present invention. Additive-1 : Sumilizer-GA80 (trademark: manufactured by Sumitomo Chemical Co., Ltd.): 3,9-bis (2- (3- (3-t-butyl-4-hydroxy-5-methylphenyl) -propionyloxy) -1,1-dimethylethyl) -2,
4,8,10-Tetraoxspio (5,5) undecane is a compound belonging to the general formula (I) of the present invention. Additive-2 : 5,7-di-t-butyl-3- (3,4di-methylphenyl) -3H-benfuran-2-one (the following formula (Formula 1)), the general formula (II) of the present invention. ) Is a compound belonging to. (Chemical formula 1) Additive-3 : Irganox 1010 (trademark: manufactured by Ciba Specialty Chemicals Co., Ltd.): Triskis (methylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) methane. Additive-4 : Sumilizer-TP-D (trademark: manufactured by Sumitomo Chemical Co., Ltd.): Pentaerythrityl-tetrakis (3
-Lauryl thiopropionate).

Example 1 and Comparative Examples 1-2 After blending the respective components in the proportions (weight ratios) shown in Table 1,
Toyo Seiki Co., Ltd. Labo Plastomill 280 ℃ 8
Knead at 0 rpm for 5 minutes, observe the final kneading torque,
The sample after kneading was taken out and pulverized, and then the melt index (MI) was measured. The less the polystyrene deteriorates, the higher the final kneading torque and the lower the MI. The results are shown in Table 1.

(1) Melt Index (MI) The melt index of each resin composition was measured at 200 ° C. under a load of 5 kg.

[0028]

[Table 1]

As shown in Example 1 and Comparative Examples 1 and 2 above, by using the specific additive of the present invention,
It was found that the decomposition of the polystyrene resin at high temperature can be significantly suppressed.

[0030]

As described above, according to the present invention,
It is possible to obtain a thermoplastic resin composition having sufficient stability even under high temperature processing conditions.

Claims (2)

[Claims] 1. A synthetic resin stabilizer represented by the following general formula (I) in an amount of 0.05 to 2 parts by weight and 100 parts by weight of a polystyrene resin (A) and the following general formula (II). The lactone-based additive is added in an amount of 0.02 to 2 parts by weight. (In the formula (I), R ₁ represents an alkyl group having 1 to 3 carbon atoms.) (In the formula (II), R _2, R ₃ and R ₄ each independently represents a hydrocarbon group or substituted hydrocarbon group, R _2, R ₃ and R ₄ and the other two or more of them with each other They may combine with each other to form a saturated or unsaturated hydrocarbon ring.) 2. A polystyrene resin (A) 5 to 95% by weight, and a polyphenylene ether resin (B) 5 to 95
% Of the resin composition containing 100% by weight, and 0.05 to 2 parts by weight of the stabilizer for synthetic resin represented by the general formula (I) of claim 1 and the general formula of claim 1. (I
A thermoplastic resin composition comprising 0.02 to 2 parts by weight of a lactone-based additive represented by I).