JP4679201B2 - Thermoplastic resin composition - Google Patents

Description

  The present invention relates to a thermoplastic resin composition having excellent thermal stability.

  Thermoplastic resins are excellent in electrical insulation, mechanical properties and chemical resistance, have low specific gravity, and are used in various applications such as daily necessities, home appliances, office machines, and industrial parts because of their excellent molding processability. However, since it is molded by injection molding, compression molding, blow molding or the like, it is required that the material that has received heat does not deteriorate, and it is often used by adding a heat stabilizer. For example, in the case of rubber reinforced polystyrene, 2,6-di-tert-butyl-4-methylphenol, which is generally a hindered phenol compound, n-octadecyl-3- (3,5 di-tert-butyl-4) -Hydroxyphenyl) propionate, triethylene glycol-N-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, etc. are used as heat stabilizers. These hindered phenol-based heat stabilizers are known to exert excellent effects on polybutadiene-based rubbers, and are particularly widely used as heat stabilizers for rubber-reinforced styrene resin compositions. These heat stabilizers generally have a low molecular weight, and it has been feared that not only the heat resistance is lowered but also volatile gas is generated during processing. In the case of methacrylic resins, there is no useful heat stabilizer, and it is necessary to control the molding temperature and the like.

  On the other hand, polyphenylene ether is not used alone in injection molding applications and has been developed as a polymer alloy blended with other resins. In particular, blends with polystyrene resins are manufactured and sold in various ratios because they are completely compatible in all ratios. Patent Document 1 describes a resin composition of polyphenylene ether and polystyrene resin as a polyphenylene ether resin composition having excellent thermal stability. However, in this resin composition, 2,6-ditertiarybutyl-4-methylphenol and bis (2,6-ditertiarybutyl-4-methylphenyl) entaerythritol-di-phos are used as heat stabilizers. The addition of fights is described. The polyphenylene ether used also has a relatively large molecular weight of intrinsic viscosity η = 0.4, and the content is 5 to 85 parts by weight with respect to 100 parts by weight of the total of polyphenylene ether and polystyrene resin, and is used as a heat stabilizer. More than quantity.

Also, a method for producing a low molecular weight polyphenylene ether having a reduced viscosity η (sp / c) of 0.07 to 0.30 is disclosed in Patent Document 2, and the blending composition of the low molecular weight polyphenylene ether is blended because of its good fluidity. There is a description that it has been found that the blend composition obtained by mixing them with other resins exhibits extremely excellent characteristics. However, the blend composition is not specified and there is no detailed description regarding the superior properties.
Japanese Patent No. 3473628 Japanese Patent Publication No. 50-6520

  An object of this invention is to provide the thermoplastic resin composition excellent in thermal stability.

As a result of intensive studies to solve the above problems, the present inventors have added a small amount of polyphenylene ether having a specific concentration of hydroxyl group to the thermoplastic resin, thereby improving the thermal stability without changing the physical properties of the thermoplastic resin. As a result, the present invention has been found.
That is, the present invention
1. A thermoplastic resin composition comprising 0.03 to 3 parts by weight of a polyphenylene ether (A) having a hydroxyl group of 120 to 2000 μmol / g as a heat stabilizer with respect to 100 parts by weight of the thermoplastic resin (B). 2. 2. The reduced viscosity (ηsp / c) of polyphenylene ether (A) measured at 30 ° C. with a chloroform solution having a concentration of 0.5 g / dl is 0.04 to 0.25 dl / g. 2. The thermoplastic resin composition described 3. The thermoplastic resin composition according to claim 1 or 2, wherein the thermoplastic resin (B) is an aromatic monovinyl resin. The thermoplastic resin composition according to claim 1 or 2, wherein the thermoplastic resin (B) is a methacrylic resin.

  According to the present invention, it is possible to provide a thermoplastic resin composition having excellent thermal stability.

  The polyphenylene ether (A) used as a heat stabilizer in the present invention is required to have a hydroxyl group of 120 to 2000 μmol / g, preferably 300 to 1500 μmol / g, more preferably 400 to 1000 μmol / g. The polyphenylene ether (A) of the present invention has a phenolic hydroxyl group at the end of the molecular chain, but may have a hydroxyl group at one or both ends. Furthermore, the hydroxyl group is not limited to the hydroxyl group at the end of the molecular chain, but includes those present in the molecular chain. When the number of hydroxyl groups per molecular chain is the same, the lower the molecular weight, the higher the hydroxyl group concentration. In order to have a hydroxyl group concentration of 120 to 2000 μmol / g, the molecular weight is inevitably relatively low. Since polyphenylene ethers usually used for injection molding and the like have a relatively large molecular weight, they generally have a hydroxyl group of 100 μmol / g or less. A hydroxyl group, particularly a phenolic hydroxyl group at the molecular chain terminal, is presumed to have an effect of trapping radicals, and polyphenylene ether having a hydroxyl group of 120 to 2000 μmol / g exhibits an effect as a heat stabilizer.

  The polyphenylene ether (A) of the present invention is a phenol homopolymer or copolymer. Specific examples of polyphenylene ether homopolymers that can be used in the present invention include poly (2,6-dimethyl-1,4-phenylene ether) and poly (2-methyl-6-phenyl-1,4-phenylene ether). , Poly (2,6-dichloro-1,4-phenylene ether) and the like. Specific examples of the polyphenylene ether copolymer include 2,6-dimethylphenol and other monohydric phenols (for example, 2,3,6-trimethylphenol and 2-methyl-6-methylbutylphenol), 2,6-dimethylphenol. And a copolymer of divalent phenols (for example, tetramethylbisphenol A). Among them, poly (2,6-dimethyl-1,4-phenylene ether), a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, 2,6-dimethylphenol and tetramethylbisphenol A These copolymers can be preferably used.

In general, polyphenylene ethers can be produced by the methods disclosed in U.S. Pat. Nos. 3,306,875, 3,344,116 and 3,342,466, JP-B 36-18692, JP-B 60-34571, and JP-A-62. Many production methods have been proposed including the -39628 publication. When producing a low molecular weight polyphenylene ether, a method of controlling the molecular weight at the time of polymerization or a method of mixing a high molecular weight polyphenylene ether with a phenolic compound, a peroxide, etc., and heating and reacting can be used.
The polyphenylene ether (A) of the present invention may contain a functional group in the molecular chain, and the hydroxyl group may be modified with a functional group, a resin having a functional group, or the like as long as the effects of the present invention are not impaired. Examples of the functional group include a vinyl group, an allyl group, an epoxy group, a carboxyl group, an acid anhydride group, an ester group, a hydroxyl group, an amino group, an amide group, and an imide group, and one or more selected from these groups. Can be included. Examples of the resin having a functional group include an epoxy resin.

The polyphenylene ether (A) of the present invention has a reduced viscosity (ηsp / c) measured at 30 ° C. with a chloroform solution having a concentration of 0.5 g / dl of 0.04 to 0.25 dl / g, preferably 0. 0.04 to 0.18 dl / g, more preferably 0.06 to 0.13. Polyphenylene ether having a hydroxyl group of 120 μmol / g and a reduced viscosity (ηsp / c) in the range of 0.04 to 0.25 dl / g has the most effective effect as a heat stabilizer.
The polyphenylene ether (A) of the present invention needs to be added in an amount of 0.03 to 3 parts by weight, preferably 0.05 to 1.5 parts by weight, more preferably 100 parts by weight of the thermoplastic resin (B). Is 0.05 to 0.8 part by weight. When the content is in the range of 0.03 to 3 parts by weight, the thermal decomposition temperature can be increased and thermal stability can be imparted without changing the heat resistance and mechanical properties of the thermoplastic resin. Further, since the polyphenylene ether (A) of the present invention has a high thermal stability with a thermal decomposition starting temperature of 450 ° C., it does not thermally decompose to generate a volatile gas.

The polyphenylene ether (A) of the present invention can be used in combination with other heat stabilizers such as hindered phenol stabilizers. Particularly in the case of polystyrene reinforced with rubber, the polyphenylene ether (A) of the present invention is effective for increasing the thermal decomposition temperature of polystyrene, and the hindered phenol compound is effective for improving the thermal stability of rubber.
Examples of the thermoplastic resin (B) used in the present invention include aromatic monovinyl resin, methacrylic resin, polyvinyl chloride, polyamide, polycarbonate, fluororesin, and polyaceter.
Le, Po triethylene terephthalate, polybutylene terephthalate, do not, but aromatic polyester Le etc. is not limited thereto. Of these, aromatic monovinyl resins and methacrylic resins are preferred. The thermoplastic resin used in the present invention is not limited to one type, and two or more types can be mixed and used.

  The aromatic monovinyl resin used in the present invention includes not only styrene alone but also a mixture of styrene with other vinyl monomers copolymerizable with styrene as the aromatic monovinyl monomer used as a raw material. Can do. Other vinyl monomers copolymerizable with styrene include methyl methacrylate, methyl acrylate, butyl acrylate, ethyl methacrylate, halogen-containing vinyl monomers, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl There are styrene, acrylonitrile and the like, and one or more of these can be used. The resin comprising an aromatic monovinyl monomer may contain polybutadiene, styrene-butadiene copolymer, polyisoprene, nitrile rubber, natural rubber or the like as a rubber component.

  The methacrylic resin used in the present invention is a methyl methacrylate homopolymer or a copolymer of a mixture of methyl methacrylate and another copolymerizable monomer having a vinyl group. Examples of monomers that can be copolymerized include methacrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, and 2,2,2-trifluoroethyl methacrylate. Examples thereof include vinyl compounds such as esters, acrylonitrile and styrene, acid anhydrides such as maleic anhydride and itaconic anhydride, and maleimide compounds such as cyclohexylmaleimide and phenylmaleimide.

The production method of the aromatic monovinyl resin and methacrylic resin of the present invention is not particularly limited, and can be produced by an existing polymerization method.
Moreover, the manufacturing method of the resin composition of this invention is not specifically limited. A method of blending with a Henschel mixer, tumbler, blender or the like and then melt-kneading with an extruder, kneader or the like is generally used. A method is also used in which polyphenylene ether is blended with a thermoplastic resin at a high concentration and melted to obtain pellets and then added to the thermoplastic resin as a master batch.
Moreover, a flame retardant, various stabilizers, a dye / pigment, and a filler can be added to the resin composition of this invention as needed.

<Polyphenylene ether>
[Synthesis Example 1]
・ Polyphenylene ether-1
A reactor with a jacket of 1.5 liters equipped with a sparger for introducing an oxygen-containing gas at the bottom of the reactor, a stirring turbine blade and a baffle, and a reflux condenser in the vent gas line at the top of the reactor was added with 0.2512 g of chloride chloride. Dicopper dihydrate, 1.1062 g of 35% hydrochloric acid, 3.6179 g of di-n-butylamine, 9.5937 g of N, N, N ′, N′-tetramethylpropanediamine, 211.63 g of methanol and 493.80 g of n-butanol and 180.0 g of 2,6-dimethylphenol containing 2.5 mol% of 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane were charged. The composition weight ratio of the solvent is n-butanol: methanol = 70: 30. Next, oxygen was introduced from the sparger into the reactor at a rate of 180 ml / min with vigorous stirring, and at the same time, the polymerization temperature was adjusted by passing a heating medium through the jacket so as to maintain 40 ° C. The polymerization solution gradually became a slurry. No adhesion was observed in the reactor during the polymerization. After 120 minutes from the start of oxygen introduction, the ventilation of oxygen was stopped, and a 10% aqueous solution of ethylenediaminetetraacetic acid tripotassium salt (a reagent manufactured by Dojindo Laboratories) was added to the resulting polymerization mixture, and the mixture was warmed to 50 ° C. Subsequently, hydroquinone (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added little by little, and the temperature was kept at 50 ° C. until the slurry polyphenylene ether became white. After completion, the mixture was filtered, and the residual wet polyphenylene ether was added to a methanol washing solvent containing 50% water, followed by stirring at 60 ° C. Subsequently, the mixture was filtered again, and the residue was sprinkled with methanol containing 50% water to obtain wet polyphenylene ether. Subsequently, it vacuum-dried at 110 degreeC and obtained polyphenylene ether-1. Reduced viscosity ηsp / c 0.115, hydroxyl group 600 μmol / g

[Synthesis Example 2]
・ Polyphenylene ether-2
The polyphenylene ether 2 was prepared in the same manner as in Synthesis Example 1 except that the composition weight ratio was n-butanol: methanol = 30: 70 and 2,6-dimethylphenol was used as the phenol compound without changing the total amount of the solvent used. Obtained. Reduced viscosity ηsp / c 0.085, hydroxyl group 420 μmol / g

[Synthesis Example 3]
・ Polyphenylene ether 3
The composition was synthesized except that the composition weight ratio was xylene: n-butanol: methanol = 60: 20: 20, methanol was used as the washing solvent, and the phenol compound was used as 2,6-dimethylphenol without changing the total amount of the solvent used. Polyphenylene ether 3 was obtained by the method of Example 1. Reduced viscosity ηsp / c 0.476, hydroxyl group 60 μmol / g

[Reduced viscosity (ηsp / c)]
The polyphenylene ether was measured as a 0.5 g / dl chloroform solution at 30 ° C. using an Ubbelohde viscosity tube. The unit is dl / g.

[Number of hydroxyl groups]
Polymer Papers, vol. 51, no. 7 (1994), according to the method described on page 480, the change in absorbance at 318 nm when a tetraammonium hydroxide solution was added to a methylene chloride solution of polyphenylene ether was measured by an ultraviolet-visible absorptiometer and calculated.

<Aromatic monovinyl resin>
Rubber-reinforced polystyrene (PSJ-polystyrene H9407 manufactured by PS Japan Co., Ltd.)
<Methacrylic resin>
Methyl methacrylate / methyl acrylate copolymer (Delpet 80NH, manufactured by Asahi Kasei Chemicals Corporation)
<Hindered phenol compounds>
n-octadecyl-3- (3,5di-t-butyl-4-hydroxyphenyl) propionate (Irganox 1076, manufactured by Ciba Specialty Chemicals)
<Thermal decomposition temperature>
The temperature was increased at 20 ° C./min under a nitrogen atmosphere using TGA-50 manufactured by Shimadzu Corporation, and the thermogravimetric change was measured. The temperature at which 5% and 10% weight decreased was defined as the thermal decomposition temperature.

[Examples 1 to 5 and Comparative Examples 1 to 4]
They were blended at the composition ratio shown in Table 1, mixed, melt-kneaded at 200 ° C. using a 30 mmφ single-screw extruder (Ishikawa Tekko Co., Ltd. HS-30), and pelletized. The pyrolysis temperature was measured using the obtained pellets.

  It can be seen that the thermal decomposition temperature of the thermoplastic resin is increased by blending a predetermined amount of the polyphenylene ether defined in the present invention.

  The resin composition of the present invention can be suitably used for various applications such as daily necessities, household appliances, office machines, and industrial parts in which a thermoplastic resin is used.

Claims (4)

  A thermoplastic resin composition comprising 0.03 to 3 parts by weight of a polyphenylene ether (A) having a hydroxyl group of 120 to 2000 μmol / g as a heat stabilizer with respect to 100 parts by weight of the thermoplastic resin (B). .   2. The reduced viscosity (ηsp / c) of polyphenylene ether (A) measured at 30 ° C. in a chloroform solution having a concentration of 0.5 g / dl is 0.04 to 0.25 dl / g. The thermoplastic resin composition as described.   The thermoplastic resin composition according to claim 1 or 2, wherein the thermoplastic resin (B) is an aromatic monovinyl resin.   The thermoplastic resin composition according to claim 1 or 2, wherein the thermoplastic resin (B) is a methacrylic resin.