JPH03126764A - Resin composition for molding - Google Patents

Abstract

PURPOSE:To provide a molding resin composition having excellent blow moldability, solvent resistance, etc., and especially suitable for preparing blow moldings for automotive exteriors by comprising polyphenylene ether resin, a specific impact-resistant polystyrene and a rubbery elastomer. CONSTITUTION:A resin composition comprises (A) 15-80 pts.wt. of polyphenylene ether resin, preferably poly (2,6-dimethyl-1,4-phenylene) ether having a reducing viscosity of 0.3-0.7dl/g (25 deg.C, in chloroform), (B) 20-85 pts.wt. of impact-resistant polystyrene resin having an elastomer content of 1-20wt.%, a swelling degree of 10-16 times using toluene as a swelling agent and a graft degree of 150-250% wherein an elastomer phase comprising polybutadiene as a main component and having a number-average particle size of 2-8mum is dispersed in polystyrene having a weight-average mol.wt. of 2X10<5> to 5X10<5>, and (C) 0-25 pts.wt. of a rubbery elastomer.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a polyphenylene ether resin composition having excellent solvent resistance and impact resistance, and in particular to a resin composition suitable for blow molding for automobile exteriors. .

(Conventional technology) In the past, most automotive air spoilers were manufactured using sheet molding compound (SMC), but in recent years, more and more cases have been manufactured using blow molding for the purpose of reducing costs and weight. .

There are various resins for blow molding, but modified polyphenylene ether resin has good parison stability during blow molding, with almost no sagging of the parison, and it can be stretched relatively evenly during molding. Because of this, molded products with uniform wall thickness can be obtained. In addition, modified polyphenylene ether resin is used for blow molding of automotive exterior parts because it has excellent performance as a blow molding resin with superior impact resistance and heat resistance compared to other blow molding resins such as polypropylene. In most cases, .

[Problem to be solved by the invention]

Automotive exterior parts such as air spoilers are painted and then attached to the vehicle body. After installation, a special wax is applied to the entire vehicle body to protect the paint film. This wax is removed using a wax remover immediately before sale.

However, when automotive exterior parts are molded with modified polyphenylene ether resin, removing the wax with a wax remover can cause cracks to occur in the parts where stress is concentrated, such as when installing exterior parts made using the metal insert method. The problem was that there was a lot to do.

By the way, this wax remover is usually a petroleum-based solvent, and wax removers with ingredients similar to kerosene are also used.

(Means for Solving the Problems) The present inventors have developed a modified polyphenylene ether resin that has excellent wax remover resistance without reducing its suitability for blow molding, such as the excellent heat resistance, impact resistance, and parison stability of modified polyphenylene ether resin. As a result of intensive studies to obtain an ether resin, a method was found that could solve this problem by blending a specific impact-resistant polystyrene resin, and the present invention was achieved.

That is, the gist of the present invention is that, when the total amount of the following components is 100 parts by weight, (A) 15 to 80 parts by weight of polyphenylene ether resin, (B) polystyrene with a weight average molecular weight of 2 x 105 to 5 x 105, containing polybutadiene as the main component. impact-resistant polystyrene in which an elastic phase with a number average particle diameter of 2 to 8 μm is dispersed, the content of the elastic body is 1 to 20% by weight, and the swelling measured using toluene as a swelling agent. A molding resin composition comprising 20 to 85 parts by weight of an impact-resistant polystyrene resin having a polystyrene of 10 to 16 times and a graft ratio of 150 to 250%, and (C) 0 to 25 parts by weight of a rubber-like elastic material. .

- The polyphenylene ether resin (A) used in the present invention is a homopolymer or copolymer represented by the following formula.

(In the formula, Q1 to Q' are each independently selected from hydrogen, a lower alkyl group, and a phenyl group, and examples of the lower hydrocarbon group include a methyl group, an ethyl group, a propyl group, and a butyl group.As a phenyl group, a toluyl group is used. (2,6-cymethyl-1.4
-phenylene)ether, poly(2,6-diethyl-1)
, 4-phenylene) ether, poly(2,6-diprobyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4 phenylene) ether, poly(2-phenylene) ether,
-methyl-6-broby-1,4-phenylene) ether, poly(2-ethyl-6-broby-1,4-phenylene) ether, (2,6-dimethyl-1,4-phenylene) ether and (2,3, 6-)dumethyl-1,4-
Copolymer with (2,6-diethyl-1,4-phenylene)ether and (2,3,6-)phenylene)ether
A copolymer with dimethyl-1,4-phenylene) ether, a copolymer with (2,6-dimethyl-1,4-phenylene) ether and (2,3,6-driethyl-1,4 phenylene) ether, etc. can be mentioned. Among these, poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-dimethyl-1,4-phenylene) ether and (2,3,6-dimethyl-1,4-phenylene) ether A copolymer of poly(2,
More preferred is 6-dimethyl-1,4-phenylene)ether.

These polyphenylene ether resins are compatible with polystyrene resins at all blending ratios.

The degree of polymerization of the polyphenylene ether resin used in the present invention is not particularly limited, but the reduced viscosity at 25°C in chloroform solvent is 0.3 to 0.7 dfl/
g is preferably used. Reduced viscosity is 0.3
If the reduced viscosity is less than dI2/g, the thermal stability tends to decrease, and if the reduced viscosity exceeds 0.7d, 9/g, the moldability tends to be impaired. These polyphenylene ether resins may be used alone or in combination of two or more.

The impact-resistant polystyrene used in the present invention is a polystyrene containing 1 to 20% by weight of an elastic body mainly composed of polybutadiene, and if this content is less than 1% by weight, the impact resistance will be poor; If it exceeds %, the viscosity becomes high during polymerization, resulting in poor productivity. Further, the elastic body contained in this impact-resistant polystyrene is dispersed in the form of particles, and the dispersed particle size must be 2 to 8 μm. The dispersed particle size can be measured by staining a molded sample with osmium tetroxide and observing an ultrathin section with a transmission microscope. If the particle size is less than 2 μm, molded products made from the composition will have poor solvent resistance, cracks will occur on the surface upon contact with the solvent, and the product will sometimes break.

On the other hand, if the size exceeds 8 .mu.m, the surface appearance of the resin molded product will be significantly degraded, and surface polishing treatment before painting will become difficult. Note that the polystyrene herein is not limited to a styrene homopolymer, and may be a copolymer with a styrene derivative such as chlorstyrene or α-methylstyrene as long as the styrene component is 50% by weight or more. The weight average molecular weight of this polystyrene is 2 x 105
~5x105. Weight average molecular weight is 2X
If it is less than IO5, the solvent resistance will be poor, and if it is more than 5XIO5, the fluidity will be too low and molding will tend to be difficult. This high-impact polystyrene must have a degree of swelling of the elastomer phase of 10 to 16 times as measured using toluene as a swelling agent. This degree of swelling is determined by adding 50 mj2 of toluene to about 1 g of high-impact polystyrene sample at room temperature.
After swelling for 8 hours, toluene-soluble components (mainly polystyrene) were removed by decanting method, and the weight of the toluene-swollen product (X)
is then vacuum dried to obtain the weight of the dry product (Y
) to measure. The degree of swelling is determined by X/Y. If the degree of swelling is less than 10 times, the impact resistance will be insufficient, and if it exceeds 16 times, the solvent resistance will be insufficient. The degree of swelling of the elastic 8-body phase can be adjusted by adjusting the amount of organic peroxide added, polymerization conditions, etc. during styrene polymerization in the presence of polybutadiene, and is also influenced by the thermal history experienced by the rubbery polymer.

The grafting rate of high-impact polystyrene is 150-250%
and preferably 170 to 230%. This grafting rate can be measured by the following method.

Precisely weigh out approximately 1.5 g of impact-resistant polystyrene resin (this will be referred to as P (g)), and add 30 m of methyl ethyl ketone to this.
After centrifugation, the soluble components were removed by decanting, and after vacuum drying, the weight of the insoluble components (X, (g)
). From these values, a value G (%) defined as the gel content is determined by equation (1). This value and the weight fraction R of the elastic body present in the impact-resistant polystyrene resin
(%), the grafting rate Y (%) is determined by equation (2). Note that R is determined from the composition of impact-resistant polystyrene at the time of manufacture.

Gel content G (%) - X/PX100 (1,) Grafting rate Y (%) = [(G/R) -1] If it is less than 150%, solvent resistance will be insufficient and impact resistance will also decrease.

This grafting rate can be adjusted by adjusting the charging ratio of monomer and rubbery polymer during production, the amount of chain transfer agent such as mercaptan, the amount of organic peroxide, etc.

The above-mentioned components (A) and (B) are essential for the composition of the present invention, but in addition to these components, a rubber-like elastic body (C) may be added if necessary.

The term "rubber-like elastic material" as used herein refers to a polymer that exhibits rubber elasticity at room temperature, including polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, styrene-butadiene-styrene block copolymer, polyisoprene, and isoprene. - Diene rubbers such as styrene copolymers and polychlorobutadiene; Isobutylene rubbers; (meth)acrylate rubbers such as butyl acrylate crosslinked polymers; Olefin rubbers such as EPDM; Urethane rubbers; Examples include ether rubber, silicone rubber, and epichlorohydrin rubber.

Furthermore, a graft-modified rubber-like elastomer obtained by graft-polymerizing various monomers onto the above-mentioned rubber can also be used. Styrene, α-
Examples include styrene monomers such as methylstyrene and vinyltoluene, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, and (meth)acrylate monomers such as methyl methacrylate, ethyl acrylate and butyl acrylate. It is also possible to use a combination of two or more types. These rubber-like elastic bodies or graft-modified rubber-like elastic bodies contain the above-mentioned components (A) and (B).
When mixed with the resin composition to form the composition of the present invention, it is preferable that the particles are dispersed in the resin composition as particles having an average particle size of 1 μm or less. Among the graft-modified rubbers mentioned above, butadiene rubber grafted with styrene or acrylonitrile/styrene, dimethylsiloxane rubber grafted with styrene or methyl methacrylate or acrylonitrile/styrene, and composite rubber in which dimethylsiloxane rubber and butyl acrylate rubber are intertwined with each other and styrene or methyl Preferred examples include graft composite rubbers grafted with methacrylate or acrylonitrile/styrene.

In the present invention, when the total amount of resin components is 100 parts by weight,
Component (A) is 15 to 80 parts by weight, preferably 30 to 70 parts by weight.
parts, component (B) is 20 to 85 parts by weight, preferably 30 to 70 parts by weight, and component (C) is 0 to 25 parts by weight. If the amount of component (A) is less than 15 parts by weight, heat resistance will be insufficient, and the parison will noticeably sag during blow molding, making molding difficult. Ingredient (A)
If it exceeds 80 parts by weight, fluidity decreases and molding becomes difficult. If component (B) is less than 20 parts by weight, impact resistance will be low, and if it exceeds 85 parts by weight, heat resistance will be reduced. If component (C) exceeds 25 parts by weight, the amounts of component (A) and component (B) will decrease accordingly, and the heat resistance and stability of the parison during blow molding will decrease.

The resin composition of the present invention is obtained by mechanically mixing component (A), component (B), and if necessary component (C), and if necessary, a flame retardant, an antioxidant, etc. This can be carried out using a Banbury mixer, roll mill, twin-screw kneading extruder, etc. as appropriate.

(Example) The present invention will be explained in more detail using Examples below. In the Reference Examples and Examples, "parts" indicate parts by weight unless otherwise specified.

In addition, the Izot impact strength is ASTM D-256 (6
For the solvent resistance test, a wax remover resistance test was conducted using a cantilever method. Three types of wax removers were used: CPC, Sr1, and Uncoater A manufactured by Yushiro Chemical Co., Ltd.

The cantilever method involves applying a solvent to one side of a test piece that is 6 inches long, 1/2 inch wide, and 1/8 inch thick, so that the side to which the solvent is applied is the side that will be stretched. The maximum stress is 200 k when supported at 3 points at room temperature (23℃).
This is a method of applying stress to a value of g/cm2 and determining the time until the test piece breaks.

In addition, the moldability was evaluated using a DA50S type blow forming machine (horizontal extrusion part screw diameter 50 mm) manufactured by Braco, with cylinder temperature of the horizontal extrusion part set at 260°C, cylinder temperature of the vertical extrusion part 270°C, and a weight part of 1 kg. The moldability was determined by whether or not the intended molded product was obtained by molding the blow-molded product, and whether or not the thickness of the molded product was constant when the molded product was obtained.

A solution of polybutadiene with a molecular weight of 180,000.1,2-vinyl content of 10% dissolved in styrene monomer at the blending ratio shown in Table 1 was added to a solution containing 0.0% of the styrene monomer.
088m01% benzoyl peroxide was added, and the conversion rate of styrene monomer was about 3 at the temperature listed in Table 1 while stirring.
Initial polymerization was carried out until it reached 5%. Next, dicumyl peroxide was added and dissolved in the amount shown in Table 1, and 3 times the amount of distilled water containing 0.64% by weight of sodium carboxycellulose was added and stirred to form a styrene monomer solution of the polymer. suspended in water. While further stirring, the mixture was allowed to react at 12'O<0>C for 5 hours and then at 14<0>C for 5 hours. The weight average molecular weight of the polystyrene in the resulting impact resistant polystyrene was determined by extracting a soluble component (styrene homopolymer) from this impact resistant polystyrene with methyl ethyl ketone, and determining the weight average molecular weight by gel permeation.

The number average particle diameter of the elastic phase was determined from the diameters of 200 to 300 particles in a thin layer photograph taken using a transmission microscope. These values, toluene swelling degree, and grafting rate are shown in Table 1.

Reference Example 2 A rubber-based graft polymer (B-1 2 parts of tetratechnoxysilane, 0.5 parts of γ-methacryloyloxybrobyl dimethoxysilane and 97.5 parts of octamethylcyclotetrasiloxane were mixed to form siloxane mixture 1.
I got 00 copies.

Distilled water in which 1 part each of sodium dodecylbenzenesulfonate and dodecylbenzenesulfonic acid was dissolved 200
100 parts of the above siloxane mixture were added to the mixture, prestirred using a homomixer at a rotational speed of 11,000 rpm, and then emulsified and dispersed using a homogenizer at a pressure of 300 kg/cm2 to obtain an organosiloxane latex. This latex is transferred to a separable flask equipped with a condenser and a stirring blade, heated at 80°C for 5 hours with stirring, then left at 20°C for 48 hours, and then neutralized with an aqueous sodium hydroxide solution. Polyorganosiloxane latex is produced by terminating the polymerization.
I got 1. The polymerization rate of the obtained polyorganosiloxane rubber was 89.7%, and the average particle diameter was 0.16 μm.

Put 25 parts by weight of this polyorganosiloxane latex into a flask, add 53.3 parts by weight of distilled water, replace the inside of the flask with nitrogen, set the internal temperature to 60°C, and add 7.35 parts by weight of n-butyl acrylate. A mixed solution of 0.15 parts by weight of allyl methacrylate and 0.038 parts by weight of tert-butyl hydroperoxide was added, and in this state 3 parts by weight were added.
This mixture was allowed to permeate into the polyorganosiloxane rubber particles by allowing the mixture to stand for 0 minutes with stirring. Next, a mixed solution of 0.00025 parts by weight of ferrous sulfate, 0.00075 parts by weight of ethylenediaminetetraacetic acid disodium salt, 0.06 parts by weight of Rongalit and 4.2 parts by weight of distilled water was added to this to initiate radical polymerization. The polymerization was completed by maintaining the internal temperature at 70° C. for 2 hours to obtain a composite rubber latex.

The average particle diameter of this composite rubber was 0.20 μm. The gel content of this composite rubber measured by extraction with toluene at 90° C. for 12 hours was 98.0% by weight.

A mixed solution of 0.048 parts by weight of tert-butylhydro1 peroxide and 10 parts by weight of styrene was added dropwise to this composite rubber latex at 70°C over 60 minutes, and after the dropwise addition was completed, the graft polymerization was maintained at 70°C for 4 hours. I let it happen. The polymerization conversion rate of styrene was 98.5%.

The obtained graft copolymer latex was dropped into 200 parts by weight of hot water containing 1.5% by weight of calcium chloride to coagulate the latex, which was separated, dehydrated, washed, and then dried to form a composite rubber graft copolymer. Combined product (B-1) was obtained.

Examples 1 to 5, Comparative Examples 1 to 7 Impact-resistant polystyrene A-1 to A- synthesized in Reference Example 1
6. Composite rubber-based graft copolymer B synthesized in Reference Example 2
-1 and polyphenylene ether resin (poly(2,6-
dimethyl-1,4-phenylene) ether, reduced viscosity (
25°C, CHCl, ) 0.4 dl/g) were mixed at the ratio shown in Table 2 to prepare a blow molding composition.

From these compositions, a twin-screw kneading extruder (ZSK-30 model manufactured by Unirna Freibler, screw diameter 30 mm) was used.
Melt kneading extrusion at a cylinder temperature of 270°C using
Pelletize and use an injection molding machine (Promat 165/75 model manufactured by Sumitomo Heavy Industries, Ltd., mold clamping pressure 75 tons) at a cylinder temperature of 280℃ and a mold temperature of 70℃. Test pieces were molded and evaluated for impact resistance and wax remover resistance. Blow moldability was also evaluated. The results are shown in Table 2. It can be seen from this that the composition of the present invention exhibits excellent blow moldability, impact strength, and wax remover resistance.

In comparison, when impact-resistant polystyrene is not used (Comparative Example 1), when the average particle size of the elastic phase in impact-resistant polystyrene is too small (Comparative Example 2.3), the degree of toluene swelling of the elastic phase is When the grafting ratio of the impact-resistant polystyrene (more precisely, the grafting ratio of the elastic phase) is out of the range of the present invention (Comparative Example 4.5), the wax remover resistance is low, and the polyphenylene ether content is large. In this case (Comparative Example 6), the fluidity was extremely poor and molding could not be performed under the blow molding conditions described above, and the cylinder temperature was set to 30°C.
Although molding was possible for the first time as 0'C, the stability of the parison was poor, and the surface appearance, impact resistance, and wax remover resistance were also poor. Furthermore, when the amount of impact-resistant polystyrene was too large (Comparative Example 7), the parison sagged significantly and the wax remover resistance was also poor.

Note that among Examples 1 to 5, Examples 1 to 3 were more preferable from the viewpoint of moldability.

(Effects of the Invention) The composition of the present invention has excellent blow moldability and impact resistance, and also has excellent durability against solvents such as wax remover.
It has excellent performance as a blow molding resin for automobile exteriors.

3-

Claims (1)

[Scope of Claims] 1) When the total amount of the following components is 100 parts by weight, (A) polyphenylene ether resin 15 to 80 parts by weight, (B) weight average molecular weight 2 x 10^5 to 5 x 10^5. Impact-resistant polystyrene consisting of an elastomer phase with a number average particle diameter of 2 to 8 μm, which is mainly composed of polybutadiene, dispersed in polystyrene, and the elastic material content is 1 to 20% by weight, and is swollen with toluene. 20 to 85 parts by weight of a high-impact polystyrene resin with a swelling degree of 10 to 16 times as measured when used as an agent and a graft ratio of 150 to 250%, and (C) 0 to 25 parts by weight of a rubber-like elastic material. Molding resin composition.