JP2006045465A - Thermoplastic resin composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition endowed with manufacturing stability, heat resistance and impact resistance, and a molded article. <P>SOLUTION: The thermoplastic resin composition comprises a graft polymer (C), obtained by emulsion graft polymerization of a monomer mixture (B) comprising an aromatic vinyl monomer and a vinyl cyanide monomer onto a rubbery polymer (A) comprising an ethylene-propylene-non-conjugated diene copolymer having a Mooney viscosity (ML<SB>1+4</SB>(125°C)) of 15-30 and a low-molecular weight modified α-olefin copolymer, a heat-resistant polymer (D) comprising an N-substituted maleimide monomer unit, and a copolymer (E) of the aromatic vinyl monomer with the vinyl cyanide monomer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoplastic resin composition and a molded article used for automobile exterior parts and the like.

  For example, molded articles of thermoplastic resin compositions are used for automobile exterior parts such as bumpers, door mirrors, and rear spoilers. The molded product for that purpose is required to have high impact resistance and good appearance, and examples of materials that satisfy the requirements include thermoplastic resins such as ABS resin, ASA resin, and polymethyl methacrylate resin. Further, among ABS resins, a copolymer comprising an aromatic vinyl monomer, a vinyl cyanide monomer and an N-aromatic substituted maleimide, and an aromatic vinyl monomer and cyanide in the presence of a conjugated diene rubber. A heat resistant ABS resin composed of a graft polymer obtained by copolymerizing a vinyl fluoride monomer may be used.

Also, an AES resin containing a graft polymer obtained by graft polymerization of an aromatic vinyl monomer or vinyl cyanide monomer in the presence of ethylene / propylene / non-conjugated diene copolymer rubber is used. Sometimes. Since this AES resin uses an ethylene / propylene / non-conjugated diene copolymer having no double bond in the main chain as a rubber component, ultraviolet rays, oxygen and ozone are used in comparison with an ABS resin using a conjugated diene rubber. Resistance to weathering, and excellent weather resistance.
As the AES resin, for example, Patent Document 1 proposes a resin containing a graft polymer obtained by emulsion graft polymerization of an aromatic vinyl monomer to an ethylene / propylene / non-conjugated diene copolymer rubber latex. Patent Documents 2 and 3 disclose emulsion graft polymerization of an aromatic vinyl monomer and a vinyl cyanide monomer with a specific production method on an ethylene / propylene / non-conjugated diene copolymer rubber latex having a specific gel fraction. The thing containing the graft polymer obtained by this is proposed (refer patent document 2, 3).
JP-A 63-291913 Japanese Patent Laid-Open No. 63-291194 Japanese Unexamined Patent Publication No. 63-291944

However, although the AES resins described in Patent Documents 1 to 3 are excellent in production stability and heat resistance, the impact resistance may not reach a required level. That is, the AES resins described in Patent Documents 1 to 3 did not have manufacturing stability, heat resistance, and impact resistance.
An object of the present invention is to provide a thermoplastic resin composition and a molded article that solves the above-described problems and has manufacturing stability, heat resistance, and impact resistance.

The thermoplastic resin composition of the present invention is a rubbery material containing an ethylene / propylene / non-conjugated diene copolymer having a Mooney viscosity (ML _{1 + 4} (125 ° C.)) of 15 to 30 and a low molecular weight modified α-olefin copolymer. A graft polymer (C) obtained by emulsion graft polymerization of a monomer mixture (B) containing an aromatic vinyl monomer and a vinyl cyanide monomer to the polymer (A);
A heat-resistant polymer (D) containing an N-substituted maleimide monomer unit;
And an aromatic vinyl monomer-vinyl cyanide monomer copolymer (E).
In the thermoplastic resin composition of the present invention, the heat resistant polymer (D) is preferably a copolymer containing 5 to 30% by mass of an N-substituted maleimide monomer unit.
In the thermoplastic resin composition of the present invention, the content of the graft polymer (C) is 10 to 40 parts by mass with respect to a total of 100 parts by mass of the components (C) to (E). The content of D) is preferably 80 to 30 parts by mass.
The molded article of the present invention is characterized by comprising the above-described thermoplastic resin composition.

  The thermoplastic resin composition and the molded product of the present invention are excellent in manufacturing stability, heat resistance and impact resistance. Furthermore, it is excellent also in mechanical characteristics other than impact resistance.

  The thermoplastic resin composition of the present invention comprises a graft polymer (C), a heat resistant polymer (D), and an aromatic vinyl monomer-vinyl cyanide monomer copolymer (E). It is included.

<Graft polymer (C)>
The graft polymer (C) is obtained by adding a rubber polymer (A) containing an ethylene / propylene / non-conjugated diene copolymer (hereinafter abbreviated as “EPDM”) and a low molecular weight modified α-olefin copolymer. The monomer mixture (B) is obtained by emulsion graft polymerization.

[Rubber polymer (A)]
The EPDM contained in the rubber polymer (A) has a Mooney viscosity (ML _{1 + 4} (125 ° C.)) of 15 to 30. When the Mooney viscosity is less than 15, the impact resistance is insufficient and impractical, and when it exceeds 30, the emulsion stability (manufacturing stability) during production is low and impractical. Here, Mooney viscosity (ML _{1 + 4} (125 ° C.)) was measured according to JIS K 6300.

 The non-conjugated diene component in EPDM is not particularly limited, but 1,4-hexadiene, 5-ethylidene-2-norbornene, 5-vinylnorbornene, dicyclopentadiene, and the like are preferable.

  The rubber polymer (A) may contain a rubber component other than EPDM. Examples of rubber components other than EPDM include polybutadiene, hydrogenated polybutadiene, polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-butene-1- (non- Conjugated diene) copolymer, isobutylene-isoprene copolymer, acrylic rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, SEBS and other hydrogenated diene systems (block, random and homo ) (Co) polymer, polyurethane rubber, silicone rubber and the like.

The low molecular weight-modified α-olefin copolymer is one in which the α-olefin copolymer is modified with a compound having a functional group and the mass average molecular weight is 1000 to 5000. Examples thereof include modified polyethylene obtained by copolymerization of 99.8 to 80% by mass of an α-olefin and 0.2 to 20% by mass of an unsaturated carboxylic acid compound. Here, examples of the α-olefin include ethylene, and examples of the unsaturated carboxylic acid compound include acrylic acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, and maleic acid monoamide.
When this low molecular weight modified α-olefin copolymer is contained in the rubber polymer (A), the emulsion stability can be increased.

  The content of the low molecular weight modified α-olefin copolymer in the rubber polymer (A) is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of EPDM. If the content of the low molecular weight modified α-olefin copolymer is 0.1 parts by mass or more, emulsion graft polymerization can be performed more stably, but if it exceeds 30 parts by mass, the physical property balance of the obtained thermoplastic resin composition is lowered. Tend to.

  The rubbery polymer (A) preferably has an average particle size of 0.2 to 1 μm because it is excellent in the physical property balance of the obtained thermoplastic resin composition. When the average particle size is less than 0.2 μm, the impact resistance of the resulting thermoplastic resin composition may be low. When it exceeds 1 μm, the gloss tends to decrease and the surface appearance tends to deteriorate. is there.

The rubbery polymer (A) is subjected to emulsion graft polymerization in a latex state.
As a method for preparing a rubbery polymer latex, a predetermined amount of EPDM and a low molecular weight modified α-olefin copolymer is kneaded by a known melt kneading means, and sufficiently dispersed by applying a mechanical shearing force. And a method of adding the product to an aqueous medium containing an emulsifier. According to this method, a stable rubber polymer latex can be obtained.
The melt kneading means in the latex preparation method is not particularly limited, but a kneader, a Banbury mixer, and a multi-screw extruder are preferable. Moreover, as an emulsifier, anionic surfactants, such as potassium oleate and disproportionated potassium rosinate, are used, for example. The addition amount of the emulsifier is preferably 1 to 10 parts by mass with respect to 100 parts by mass of EPDM. The emulsifier may be added by, for example, mixing oleic acid in advance with EPDM and a low molecular weight modified α-olefin copolymer, and adding potassium hydroxide aqueous solution thereto to form potassium oleate. .

  The rubber polymer (A) may be one obtained by crosslinking a non-crosslinked rubber polymer. As a method for the crosslinking treatment, 0.1 to 5 parts by mass of an organic peroxide such as di-t-butyl-oxytrimethylcyclohexane and divinyl are used with respect to 100 parts by mass of the solid content of the uncrosslinked rubber polymer latex. Examples include a method in which 0.1 to 5 parts by mass of a polyfunctional compound such as benzene is added and reacted at 60 to 140 ° C. for about 0.5 to 5 hours.

[Monomer mixture (B)]
The monomer mixture (B) is a mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components and another vinyl monomer polymerizable with these as an optional component.
Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, and the like.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile.
Examples of other vinyl monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate, methyl methacrylate, ethyl methacrylate, propylene methacrylate and butyl methacrylate. Methacrylic acid alkyl ester and the like. Among these, butyl acrylate or methyl methacrylate is preferably used.
Other vinyl monomers include maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (4-hydroxyphenyl) maleimide, N -N-substituted maleimide monomers such as cyclohexylmaleimide.

  Since the composition of the monomer compound (B) is excellent in the physical property balance of the resulting thermoplastic resin composition, the aromatic vinyl monomer is 60 to 76% by mass, and the vinyl cyanide monomer is 40 to 40%. The content is preferably 24% by mass, and other vinyl monomers are 0 to 20% by mass.

[Production method of graft polymer (C)]
Examples of the method for producing the graft polymer (C) include a method in which the monomer mixture (B) is added to the latex of the rubber-like polymer (A), and the emulsion graft polymerization is performed by heating to a predetermined polymerization temperature. . In particular, the monomer mixture (B) may be continuously added to the latex of the rubbery polymer (A) over a period of 1 hour or more after mixing the redox initiator with the monomer mixture (B). preferable. When the addition time of the monomer mixture (B) is less than 1 hour, the latex stability may be lowered and the polymerization yield may be lowered.
You may add antioxidant to the graft polymer (C) after superposition | polymerization as needed.

  The redox initiator used here is preferably a combination of an oil-soluble organic peroxide and a ferrous sulfate-chelating agent-reducing agent. Examples of the oil-soluble organic peroxide include cumene hydroperoxide, diisopropylbenzene hydroperoxide, and tertiary butyl hydroperoxide. More preferred redox initiators include cumene hydroperoxide, ferrous sulfate, sodium pyrophosphate, and dextrose.

  In the graft polymer (C), 60 to 20% by mass of the monomer mixture (B) is polymerized to 40 to 80% by mass (as a solid content) of the rubbery polymer (A) ((A) and (B). ) Is preferably 100% by mass). When the rubber polymer (A) is less than 40% by mass (monomer mixture exceeds 60% by mass), the rubber polymer (A) exceeds 80% by mass (monomer mixture is 20 parts by mass). In any case, the impact resistance tends to decrease.

  A graft polymer latex is obtained by the above-described method for producing a graft polymer. As a method for recovering the graft polymer (C) from the graft polymer latex, for example, a precipitant is added to the graft polymer latex, and after heating and stirring, the precipitant is separated, washed with water, dehydrated and dried. A precipitation method is employed. As the precipitation agent in the precipitation method, for example, an aqueous solution of sulfuric acid, acetic acid, calcium chloride, magnesium sulfate, or the like can be used alone or in combination.

<Heat resistant polymer (D)>
The heat-resistant polymer (D) is not limited as long as it contains an N-substituted maleimide monomer unit, but an N-substituted maleimide monomer includes an aromatic vinyl monomer and vinyl cyanide. A copolymer obtained by copolymerizing at least one monomer selected from a system monomer and another vinyl monomer copolymerizable therewith is preferable. This heat resistant polymer (D) increases the heat resistance of the resulting thermoplastic resin composition.
The composition of the heat resistant polymer (D) is preferably 5 to 30% by mass of N-substituted maleimide monomer units. When the N-substituted maleimide monomer unit is less than 5% by mass, the heat resistance may not be increased, and when it exceeds 30% by mass, the impact resistance may be decreased.
Further, the aromatic vinyl monomer unit is preferably 40 to 60% by mass, and the vinyl cyanide monomer unit is preferably 35 to 10% by mass.
Specific examples of the aromatic vinyl monomer, vinyl cyanide monomer, N-substituted maleimide monomer, and other vinyl monomers are the same as those in the monomer mixture (B). Can be mentioned.

For the production of the heat-resistant polymer (D), a polymerization method such as emulsion polymerization or suspension polymerization is employed. When the heat-resistant polymer (D) is produced by emulsion polymerization, each monomer, an emulsifier, a polymerization initiator, and a chain transfer agent are charged into the reactor and polymerized by heating to obtain the heat-resistant polymer. The heat resistant polymer (D) is recovered from the latex by a precipitation method.
Here, general emulsifiers for emulsion polymerization such as potassium rosinate and sodium alkylbenzenesulfonate can be used as the emulsifier. Moreover, organic and inorganic peroxide initiators can be used as the polymerization initiator, and mercaptans, α-methylstyrene dimers, terpenes, and the like can be used as the chain transfer agent. As the precipitation method, a method similar to the method of recovering the graft polymer (C) from the graft polymer latex can be employed.

When producing by suspension polymerization, each monomer, suspending agent, suspending aid, polymerization initiator, and chain transfer agent are charged into the reactor, polymerized by heating, and the resulting heat resistant polymer The slurry is dehydrated to recover the heat resistant polymer (D).
Here, as the suspending agent, tricalcium phosphite, polyvinyl alcohol or the like can be used, and as the suspending aid, sodium alkylbenzene sulfonate or the like can be used. Further, organic peroxides can be used as the polymerization initiator, and mercaptans, α-methylstyrene dimer, terpenes, and the like can be used as the chain transfer agent.

<Aromatic vinyl monomer-vinyl cyanide monomer copolymer (E)>
The aromatic vinyl monomer-vinyl cyanide monomer copolymer (E) is a copolymer of an aromatic vinyl monomer and a vinyl cyanide monomer. The copolymer (E) may be copolymerized with another vinyl monomer copolymerizable with the aromatic vinyl monomer and the vinyl cyanide monomer.
Specific examples of the aromatic vinyl monomer, vinyl cyanide monomer, and other vinyl monomers include the same as the monomer mixture (B).
As a method for producing the aromatic vinyl monomer-vinyl cyanide monomer copolymer (E), the same method as the method for producing the heat-resistant polymer (E) can be employed. Moreover, you may manufacture by a block polymerization method.
Impact resistance can be ensured by including such an aromatic vinyl monomer-vinyl cyanide monomer copolymer (E) in the thermoplastic resin composition.

<Thermoplastic resin composition>
In the thermoplastic resin composition containing these (C), (D), and (E) components, the content of the graft polymer (C) is 10 to 40 parts by mass, and the content of the heat-resistant polymer (D) is It is preferable that it is 80-30 mass parts. If the graft polymer (C) and the heat resistant polymer (D) are within the above ranges, the balance between heat resistance and impact resistance is particularly excellent.

  The thermoplastic resin composition includes a graft polymer (C), a heat-resistant polymer (D), an aromatic vinyl monomer-vinyl cyanide monomer copolymer (E), and, if necessary, Antioxidants, lubricants, processing aids, pigments and fillers are mixed and pelletized with, for example, an extruder, a Banbury mixer or a kneading roll.

<Molded product>
Next, the molded product of the present invention will be described. The molded article of the present invention is obtained by molding the above-described thermoplastic resin composition. Examples of the molding method include an injection molding method, a press molding method, an extrusion molding method, a vacuum molding method, and a blow molding method.
The molded article of the present invention is suitable for automotive exterior parts such as bumpers, door mirrors, rear spoilers, etc., but can also be applied to other uses.

  EXAMPLES Hereinafter, although a manufacture example, an Example, and a comparative example are given and this invention is demonstrated further more concretely, unless this summary is exceeded, this invention is not limited to a following example. In the following, “part” means “part by mass” and “%” means “mass%”.

"Production Example 1" Production of rubbery polymer (A-1) EPDM (G2470-LM manufactured by Bayer Co., Ltd., Mooney viscosity; 20) 90 parts, low molecular weight modified polyethylene (High Wax 2203A manufactured by Mitsui Chemicals, Inc.) 10 parts and further 5 parts of potassium oleate were mixed. Then, the mixture was supplied at 4 kg / hour from the hopper of a twin screw extruder (Ikegai Steel Co., Ltd. PCM-30 type, L / D = 40), and a potassium hydroxide 15% aqueous solution was supplied at 110 g / hour. While continuously feeding, the melt was kneaded at a heating temperature of 180 ° C. to extrude the melt. Subsequently, the melt was continuously supplied to a cooling single screw extruder attached to the tip of the extruder and cooled to 90 ° C. The taken-out solid was poured into warm water at 80 ° C. and continuously dispersed to obtain a rubber polymer latex having an average particle size of 0.45 μm.

  1.15 parts of di-t-butylperoxytrimethylcyclohexane and 1.0 part of divinylbenzene are added to 100 parts of the solid content of the latex and reacted at 120 ° C. for 1 hour to give a rubbery polymer (A -1) was prepared.

[Production Example 2] Production of rubber polymer (A-2) A rubbery polymer (A-2) was produced in the same manner as in Production Example 1 except that TP3180 (Mooney viscosity; 9) manufactured by Mitsui Chemicals, Inc. was used as EPDM. -2) was produced.

“Production Example 3” Production of Graft Polymer (C-1) In a stainless steel polymerization tank equipped with a stirrer, 200 parts of ion exchange water, 50 parts of rubber polymer (A-1) as a solid content, 2 parts of potassium oleate, 0.004 part of ferrous sulfate, 0.2 part of sodium pyrophosphate and 0.2 part of dextrose were charged, and the temperature was 80 ° C. Next, a monomer mixture composed of 17 parts of acrylonitrile and 33 parts of styrene and 0.3 part of cumene hydroperoxide were continuously added for 2 hours, and emulsion graft polymerization was carried out while keeping the polymerization temperature constant at 80 ° C. The monomer conversion after the polymerization was 95%.
After the polymerization, an antioxidant is added to the obtained graft polymer latex, solid content is precipitated with sulfuric acid, and after washing, dehydration and drying, the powdered graft polymer (C-1) is obtained. Obtained.

“Production Example 4” Production of Graft Polymer (C-2) The same manner as in Production Example 3 except that the type and addition amount of the rubbery polymer and the addition amount of the monomer compound are as shown in Table 1. A graft polymer (C-2) was obtained.

[Production Example 5] Production of heat-resistant polymer (D-1) In a nitrogen-substituted stainless steel reactor with a stirrer equipped with a stirrer, 120 parts of ion-exchanged water, 0.1 part of polyvinyl alcohol, azobisisobutyronitrile, 0. 3 parts, 26 parts of acrylonitrile, 20 parts of styrene, 34 parts of α-methylstyrene, 20 parts of N-phenylmaleimide, and 0.3 part of t-dodecyl mercaptan were charged. The reactor was heated to 50 ° C. for 5 hours, heated to 120 ° C., polymerized for 4 hours, and then extracted to obtain a heat resistant polymer (D-1). The monomer conversion in the polymerization was 98%, and the obtained heat-resistant polymer (D-1) had a mass average molecular weight of 1.0 × 10 ⁵ .

"Production Example 6" Production of heat-resistant polymer (D-2) The same as Production Example 5 except that 29 parts of acrylonitrile, 24 parts of styrene, 37 parts of α-methylstyrene and 10 parts of N-phenylmaleimide were charged. A heat resistant polymer (D-2) was obtained.
The compositions of the heat resistant polymers (D-1) and (D-2) are shown in Table 2.

[Production Example 7] Production of styrene-acrylonitrile copolymer (E) In a stainless steel polymerization reactor equipped with a nitrogen-replaced stirrer, 120 parts of ion exchange water, 0.1 part of polyvinyl alcohol, azobisisobutyronitrile, 0. 3 parts, 30 parts of acrylonitrile, 70 parts of styrene, and 0.35 part of t-dodecyl mercaptan were charged. The reactor was heated to 60 ° C. for 5 hours, heated to 120 ° C., polymerized for 4 hours, and then extracted to obtain a styrene-acrylonitrile copolymer (E). The monomer conversion in the polymerization was 96%, and the mass average molecular weight of the obtained styrene-acrylonitrile (ST-AN) copolymer (E) was 1.0 × 10 ⁵ .

(Examples 1 and 2 and Comparative Examples 1 to 4)
Each component obtained by the method described above was mixed in the formulation shown in Table 3, and the mixture was melt-kneaded with an extruder to obtain a thermoplastic resin composition.

The mechanical strength, impact resistance, and heat resistance of the obtained thermoplastic resin composition were evaluated as follows. The evaluation results are shown in Table 3.
Mechanical strength: Using Toshiba Machine's injection molding machine IS55FP-1.5A, a test piece was prepared according to ISO 3167, and the bending strength was measured according to the method of ISO 178.
Impact resistance: Using Toshiba Machine's injection molding machine IS55FP-1.5A, a test piece was prepared according to ISO 3167 and measured according to the method of ISO 179.
Heat resistance: The heat distortion temperature was measured according to ASTM D648-56.

In Examples 1 and 2 satisfying claim 1 of the present application, both heat resistance and impact resistance were provided, and the bending strength was also high. Moreover, the emulsion stability during production was high and the production stability was excellent. On the other hand, Comparative Examples 1 and 2 having a Mooney viscosity of less than 15 were inferior in impact resistance. Moreover, the comparative examples 3 and 4 which do not contain a heat resistant polymer were inferior in heat resistance.
Further, when Example 1 and Comparative Example 3 having the same blending ratio are compared with Example 2 and Comparative Example 4, respectively, the higher the Mooney viscosity of EPDM (Examples 1 and 2), the higher the impact resistance. It turns out that the nature is high.
From the comparison between Example 1 and Comparative Example 4, and Comparative Example 1 and Comparative Example 3, it was found that the heat resistance was improved by blending the heat resistant polymer.

Claims (4)

A rubbery polymer (A) containing an ethylene / propylene / non-conjugated diene copolymer having a Mooney viscosity (ML _{1 + 4} (125 ° C.)) of 15 to 30 and a low molecular weight modified α-olefin copolymer is added to an aromatic vinyl. A graft polymer (C) obtained by emulsion graft polymerization of a monomer mixture (B) containing a monomer and a vinyl cyanide monomer;
A heat-resistant polymer (D) containing an N-substituted maleimide monomer unit;
A thermoplastic resin composition comprising an aromatic vinyl monomer-vinyl cyanide monomer copolymer (E).   The thermoplastic resin composition according to claim 1, wherein the heat-resistant polymer (D) is a copolymer containing 5 to 30% by mass of an N-substituted maleimide monomer unit.   The content of the graft polymer (C) is 10 to 40 parts by mass and the content of the heat resistant polymer (D) is 80 to 30 parts by mass with respect to 100 parts by mass of the total of the components (C) to (E). The thermoplastic resin composition according to claim 1 or 2, wherein   A molded article comprising the thermoplastic resin composition according to any one of claims 1 to 3.