JPS6241538B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyphenylene ether resin composition that provides molded products with high gloss and excellent appearance. A polyphenylene resin composition composed of polyphenylene ether and a rubber-modified polystyrene resin is well known as a resin composition having excellent impact resistance and heat resistance. However, polyphenylene ether resin compositions have low gloss in molded products, and various improvements have been proposed. For example, Japanese Patent Publication No. 51-28659 describes a polyphenylene ether resin composition having an elastic phase of dispersed particles having an average maximum particle size of about 2 microns. Although these prior art compositions have a high luster, they have the technical drawback of exhibiting a pearl-like appearance upon close inspection. That is, when a fluorescent light is projected onto the flat surface of a molded product made from the composition of the prior art, the outline becomes blurred and a slight iridescent color appears, giving it a pearl-like appearance. This improvement was requested because the practical value of the product was impaired. The object of the present invention is to provide a polyphenylene ether resin composition that improves this phenomenon of poor appearance and provides high gloss. In order to achieve this objective, the present inventor used polybutadiene having a specific structure as a rubber-like elastic body in a rubber-modified styrene resin that is a component of a polyphenylene ether resin composition, and The present invention was completed based on the discovery that it is effective to impart a specific structure to the soft component of To achieve the object of the present invention, in the polyphenylene ether resin composition, the structure of polybutadiene, which is a rubbery elastic body used as a raw material for the rubber-modified styrene resin, which is a constituent component, and the structure of polybutadiene, which is a rubbery elastic body, The particle size of rubber particles (hereinafter referred to as soft component particles) produced by graft polymerization of monomers such as styrene and R R = g ₁ - g ₂ /r defined by the following formula (the symbols will be described later). It is necessary to specify each of the values of but

[Formula] (However, R ₁ , R ₂ , R ₃ , R ₄ are the same or different alkyl groups having 3 or less carbon atoms, and Q ₁ , Q ₂ , Q ₃ , Q ₄ are hydrogen or the same alkyl groups having 3 or less carbon atoms. or represents a different alkyl group.m and n represent 0 or a natural number; m=
Except when n=0. ) It is a polymer represented by An example of polyphenylene ether is poly(2,6-dimethyl-1,4
-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), and the like. This can be done using known methods, such as the
It is easily produced by oxidative polymerization of the corresponding alkylphenol according to the method described in No. 1869.
The preferred degree of polymerization of polyphenylene ether (i.e., m+n in the above general formula) is such that the number average degree of polymerization is
The range is 50-400. If the number average degree of polymerization is less than 50, the mechanical properties, particularly the rigidity, of the resin composition will deteriorate, which is undesirable, and if it exceeds 400, the moldability will markedly deteriorate, which is undesirable. The monovinyl aromatic monomer used in the present invention is styrene alone or a mixture of styrene and other vinyl monomers that can be copolymerized with styrene.
Examples of other vinyl monomers that can be copolymerized with styrene include acrylonitrile, methyl methacrylate, α-methylstyrene, and nuclear-substituted monobromstyrene. The proportion of these monomers is usually 30% by weight or less, preferably 10% by weight of the total monomers.
% by weight or less. The rubber-like elastic body used in the present invention has 10 to 25 mol% of 1,2-vinyl bonds and 25 to 45 mol% of 1,4-cis bonds.
The essential requirements are a microstructure defined by mol %, 30-65 mol % 1,4-trans bonds, and a solution viscosity of 30-60 centistokes. Rubber-like elastic materials outside this range, such as high-cis polybutadiene with 1,4-cis bonds of 90 mol% or more,
When using polybutadiene with a solution viscosity of more than 60 centistokes, polybutadiene with a solution viscosity of less than 30 centistokes, styrene-butadiene copolymer rubber (SBR), etc., the resulting resin composition has poor gloss, appearance, and impact resistance. This is because it is significantly inferior to a resin composition using polybutadiene, which is a constituent element of the present invention. That is, if the 1,2-vinyl bond content is less than 10 mol%, the appearance of the composition will be poor, and if it exceeds 25 mol%, the impact resistance of the composition will decrease. If the content of 1,4-cis bonds is less than 25 mol%, impact resistance decreases, and if it exceeds 45 mol%, the appearance deteriorates. Also, the solution viscosity is 30
Impact resistance decreases below 60 centistokes.
If centistokes are exceeded, the appearance deteriorates. The solution viscosity referred to in the present invention is the solution viscosity measured using an Ubbelohde viscometer at 30° C. for a solution prepared by dissolving 5 g of rubbery elastic material in 45 g of styrene. The microstructure of polybutadiene referred to in the present invention is determined as follows. That is ^, polybutadiene is dissolved in carbon disulfide, and the infrared absorption spectrum of ^the solution is measured ^. , 4-cis bonds, the Morello method [D.Morero et al. Chim.Ind.,
41758 (1959)]. The polybutadiene used in the present invention is produced by polymerizing 1,3-butadiene using an organolithium catalyst using a known method, for example, as disclosed in JP-A-53-130793. As a method for producing the rubber-modified styrenic resin of the present invention, any known polymerization method such as emulsion polymerization, bulk polymerization, bulk-suspension two-stage polymerization, etc. can be used. Preferably, a bulk polymerization method or bulk polymerization method in which styrene or the like is polymerized in the presence of a rubber-like elastic material.
A suspension two-stage polymerization method is applied. As an example, a two-stage bulk-suspension polymerization method will be explained. First, the polybutadiene described above is added to styrene and heated to 60 to 80°C to dissolve it. It is preferable that this dissolution be as uniform as possible. then 90-120
Bulk polymerization is carried out at °C with stirring until the polymerization rate of styrene is 10-40%. This step will be referred to as a "preliminary polymerization step." In the prepolymerization step, the rubber-like elastic body is dispersed into particles under the action of stirring. After the prepolymerization step is completed, it is suspended in an aqueous phase containing tertiary calcium phosphate or the like as a suspending agent, and suspension polymerization is performed. The step after this preliminary polymerization will be referred to as the "main polymerization step." If necessary, following the main polymerization step,
A "post-heating step" may be performed in which heating is continued after the amount of monomer is reduced. The slurry thus obtained is dehydrated, and the beads are collected and dried. When polymerization is completely completed, the soft component is dispersed as particles in the hard phase of the styrene polymer in the rubber-modified styrenic resin.
The particles of the soft component are composed of a rubber-like elastic material graft-copolymerized with styrene and a styrenic polymer encapsulated therein. In order to achieve the object of the present invention, it is necessary that the average particle diameter of the soft component particles be in the range of 0.1 to 1.0 μ. If the average particle size is less than 0.1μ, the resin composition will have poor impact resistance, and if the average particle size exceeds 1.0μ, the resin composition will have poor gloss. Here, the average particle size is the one obtained by taking an electron microscope photograph of the resin using an ultra-thin section method, measuring the particle diameters of 200 to 500 soft component particles in the photograph, and averaging them by weight according to the following formula. Weight average diameter=ΣnD ⁴ /ΣnD ³ where n is the number of soft component particles having particle diameter D. The average particle diameter range specified in the present invention can be achieved by appropriately determining the stirring conditions in the prepolymerization step. In other words, increasing the number of stirrings by the stirring blade will reduce the average particle size, and decreasing the number of stirrings will increase the average particle size, so by selecting an appropriate number of stirrings, the desired average particle size can be achieved. can. In order to achieve the object of the present invention, it is necessary that R defined by the following formula satisfy 0.5<R<5.0. R=g ₁ - g ₂ /r where g ₁ is the methyl ethyl ketone insoluble content (weight percentage) after heating the rubber-modified styrenic resin in nitrogen at 300°C for 5 hours, and it is contained in the rubber-like elastic body. This means the content of soft components including monovinyl aromatic polymers. g ₂ is the methyl ethyl ketone insoluble content (weight percentage) of the rubber-modified styrene resin, and indicates the content of soft components without inclusion of monovinyl aromatic polymer. r indicates the weight percentage of the rubber-like elastic body in the rubber-modified styrene resin. Therefore, R is considered to be a measure indicating the ratio of the monovinyl aromatic polymer encapsulated in the rubbery elastic body to the rubbery elastic body. If R is less than 0.5 or more than 5.0, the appearance of the composition will deteriorate. When R is 0.7 to 2.0, the appearance of the composition is particularly good, which is preferable. R referred to in the present invention is determined as defined above, and the methyl ethyl ketone insoluble content in the definition is the weight percentage of the substance insoluble in methyl ethyl ketone, and is determined as follows. In other words, 2.0g of rubber-modified styrenic resin is mixed with methyl ethyl ketone.
Pour into 50ml and leave under reflux for 5 hours. After cooling, the insoluble matter is centrifuged, the solution is removed by slanting, the solution is dried, and the insoluble matter is weighed. When the insoluble content is xg, the methyl ethyl ketone insoluble content is determined by the following formula. Methyl ethyl ketone insoluble matter content = x / 2.0 × 100 The range of R specified in the present invention is determined by adjusting the operating conditions such as polymerization temperature and initiator used in each production method when producing a polymer by a known method. This can be achieved by properly determining. Usually this is adjusted by selecting a suitable temperature in the after-heating step and/or by adding crosslinking aids such as peroxides. In other words, the higher the temperature in the post-heating step, the smaller R will be, and when an organic peroxide is added in this step, the larger the amount of organic peroxide decomposed, the smaller R will be.
becomes smaller. Alternatively, R can also be adjusted by the polymerization temperature and decomposition amount of the initiator in the main polymerization step. That is, the lower the polymerization temperature and the greater the amount of decomposition of the initiator, the greater R becomes. This R is thought to be correlated with the amount of monovinyl aromatic polymer that is not chemically bonded to the rubber encapsulated in the soft component, and the behavior of the rubber particles when molding the resin composition is affected by this R. Since it changes depending on R, it is presumed that the appearance also changes. Any known production method can be used to produce the resin composition of the present invention. Usually, a resin composition is produced by mixing polyphenylene ether and rubber-modified styrene resin using an extruder. In the composition of the present invention, the proportion of polyphenylene ether and rubber-modified styrenic resin is about 20 to 80% by weight of polyphenylene ether, and about 80 to 20% by weight of rubber-modified styrenic resin.
It is desirable that the ratio is . If polyphenylene ether is less than 20% by weight, the heat resistance of the resin composition will be poor;
This is because if the amount exceeds 80% by weight, the molding processability will be poor. The appearance improvement (prevention of pearl pattern) of the resin composition of the present invention is clearly different from that of the prior art, and the gloss is significantly improved. The resin composition of the present invention has not only the high impact resistance and heat resistance inherent to polyphenylene ether resin compositions, but also high gloss and excellent appearance, so it is used in industrial fields such as electrical equipment. It has extremely high utility value. Specifically, it can be suitably used for housings of televisions, hair dryers, etc. This will be explained in detail below using Examples. Note that unless otherwise specified, "parts" indicate parts by weight. Example 1 A. Production of polyphenylene ether Poly(2,6-dimethyl-1,4-phenylene ether) was synthesized according to Example 1 of JP-A-50-97695. 0.41 parts of cupric bromide and 10.9 parts of di-n-butylamine were added to 100 parts of toluene and stirred to prepare a catalyst solution. While blowing air into this catalyst solution, a solution of 70 parts of 2,6-xylenol dissolved in 100 parts of toluene was added.
Added over 15 minutes. The reaction system was maintained at 30° C., and stirring and air blowing were continued for 3 hours. After the reaction
Three parts of 50% acetic acid solution was added to decompose the catalyst. The polymer solution phase was centrifuged, methanol was added to precipitate the polymer, and the polymer was separated and dried.
The number average degree of polymerization of the obtained polymer was 200. B Production of rubber-modified styrenic resin Asaprene 700X (polybutadiene, manufactured by Asahi Kasei Corporation) in a stirred polymerization tank 7 parts styrene 93 parts tertiary dodecyl mercaptan 0.05 parts (Here, Asaprene 700X contains 17 mol% of 1,2-vinyl bonds, 1 ,4-cis bond 38 mol%, 1,4
- It has a microstructure of 45 mol% trans bonds and a solution viscosity of 45 centistokes. ) and heated at 75°C for 2 hours with stirring to form a homogeneous solution. Thereafter, the stirring speed was increased to 270 rpm, and preliminary polymerization was carried out at 110° C. for 7 hours, resulting in a styrene polymerization rate of 30%. Then, the following aqueous phase was prepared in another polymerization tank with stirring, and the polymerization mixture obtained in the above prepolymerization was added and dispersed in the form of particles. Water 150 parts Tertiary calcium phosphate 3 parts Sodium dodecylbenzenesulfonate 0.02 parts Add benzoyl peroxide to this suspension.
0.30 parts and 0.02 parts of dicumyl peroxide were added, main polymerization was carried out at 85°C for 8 hours, and then at 130°C.
Heating was carried out after 2 hours. The obtained suspended particles were separated and dried. The average particle size of the particles of the soft component dispersed in this rubber-modified styrene resin was 0.70μ, and R was 1.1. C. Production of polyphenylene ether resin composition The following compound was extruded using an extruder and pelletized to obtain a resin composition. Poly(2,6-dimethyl-1,4
- Phenylene ether) 45 Rubber-modified polystyrene resin produced in Part B 55 Polyethylene 1.5 Tridecyl phosphite 0.5 Ethylene bisstearylamide 0.3 Titanium dioxide 2 D Evaluation Using the pellets obtained in C, injection molding Test pieces were prepared for measuring impact resistance and gloss, respectively, and the following measurements were performed. The results are summarized in Table 1. (1) Impact resistance measurement A 1/4 inch R striking center was applied to a square plate measuring 50m/m x 50m/m x 2.5m/m, a constant load was dropped from the top, and 50% of the test piece was destroyed. It is expressed by the energy of Fracture energy (Kg-cm) = Height of falling load (cm) x Load (Kg) (2) Gloss measurement A square plate of 140 m/m x 80 m/m x 4 m/m was polished using the JISK8741 method. It was measured. (3) Measurement of appearance Using the square plate described in (2) above, visual judgment was made according to the following criteria. Rating 1: There is no pearl-like appearance defect, and when the fluorescent light is photographed, the outline of the fluorescent light is not blurred. 2...The above phenomenon is slightly observed. 3...The above phenomenon is clearly observed. Comparative Examples 1 to 6 Resin compositions were obtained in accordance with Example 1, except that the stirring number in the rubber-like elastic material prepolymerization step as a raw material was changed as shown in Table 1. These pellets were injection molded in the same manner as above to make test pieces, and impact resistance, gloss, and appearance were measured. Comparative Examples 1, 2, and 3 have poor appearance, while Comparative Examples 4 and 6
had low impact resistance, and Comparative Example 5 had poor appearance and impact resistance, both of which were inferior in performance to the resin composition of the present invention.

[Table] Example 2 E According to the production of polyphenylene ether described in A of Example 1, 60 parts of 2,6-xylenol was used instead of 70 parts of 2,6-xylenol 2,3,6
- Polyphenylene ether, which is a copolymer of 2,6 xylenol and 2,3,6-trimethylphenol, was produced using a mixture of 10 parts of trimethylphenol. F A rubber-modified styrenic resin was produced in accordance with the production of a rubber-modified styrenic resin described in Example 1, B, using a mixture of 78 parts of styrene and 15 parts of nuclear-substituted monobrom styrene in place of 93 parts of styrene. G According to the production of the resin composition described in C of Example 1, pellets of the resin composition were obtained using the following formulation. Polyphenylene ether manufactured in E 50 parts Rubber-modified styrenic resin manufactured in F 50〃 Polyethylene 1.0〃 Tridecyl phosphite 0.70〃 Ethylene bisstearylamide 0.20 parts Titanium dioxide 3.0〃 H Using the pellets obtained in G, Measurements similar to those described in Example 1 D were performed. Table 2 shows the results.
Shown below. Comparative Example 7 Resin composition pellets were obtained in accordance with Example 2, except that the number of stirrings in the prepolymerization step was changed as shown in Table 2. These pellets were injection molded in the same manner as above to make test pieces, and impact resistance, gloss, and appearance were measured. Comparative Example 7, in which the particle size of the soft component was outside the range of the present invention, had poor gloss.

【table】

[Table] Examples 3 and 4 Resin composition pellets were obtained according to Example 1 except that the conditions of the main polymerization step and post-heating step were changed as shown in Table 3.These pellets were treated in the same manner as in Example 1. Test pieces were made by injection molding, and impact resistance, gloss, and appearance were measured. Comparative Examples 8 and 9 A resin composition having R outside the range of the present invention was produced in accordance with Example 1, except that the conditions of the main polymerization step and the post-heating step were changed as shown in Table 3. The results are shown in Table 3. Both Comparative Examples 8 and 9 had poor appearance.

【table】

【table】

Claims (1)

[Claims] 1. A composition comprising (A) a polyphenylene ether having a number average degree of polymerization of 50 to 400 and (B) a rubber-modified styrenic resin, wherein the rubber-modified styrenic resin (B) has a monovinyl aromatic A resin obtained by dissolving and polymerizing 1 to 15 parts by weight of a rubbery elastic material in 85 to 99 parts by weight of a group monomer, wherein (a) the rubbery elastic material contains 10 to 50 moles of 1,2-vinyl bonds; %, 1,4-cis bond 25-45 mol%, 1,4
- a polybutadiene having a microstructure of 30 to 65 mol % trans bonds and a solution viscosity of 30 to 60 centistokes; (b) soft component particles (the rubber-like Rubber-like particles produced by graft polymerization of an elastic body with a monovinyl aromatic monomer) are 0.1 to 1μ
(c) R defined by the following formula is 0.5 < R < 5.0 R = g ₁ - g ₂ /r (where g ₁ is 300 g ℃, is the methyl ethyl ketone insoluble content after heating for 5 hours, _g2 is the methyl ethyl ketone insoluble content in the rubber modified styrenic resin before heating, and r is the rubber-like elasticity in the rubber modified styrenic resin. body weight percentage).