JP5242986B2 - Thermoplastic resin composition and method for producing the same - Google Patents

Description

  The present invention relates to a thermoplastic resin composition (methacrylic resin composition) excellent in weather resistance, transparency, warm water whitening property, and low temperature impact resistance, and a method for producing the same.

  Methacrylic resins have excellent weather resistance, gloss and transparency, but have the disadvantage of low impact resistance, and the range of use is limited.

  As a method for imparting impact resistance while maintaining the excellent weather resistance of a methacrylic resin, there is a method of mixing a graft copolymer with a methacrylic resin. However, various types of graft copolymers have been proposed, but compositions having satisfactory physical properties have not yet been obtained. The outline and problems of typical methods (a) and (b) will be described below.

  (A) A rubbery polymer whose main component is an alkyl acrylate having excellent weather resistance and a glass transition temperature of room temperature or lower, and a glass transition temperature of room temperature or higher, which is a structural unit of a relatively hard polymer. A method of mixing a rubber-like polymer-hard polymer two-layer structure graft copolymer obtained by graft polymerization of a monomer component such as a methacrylic acid alkyl ester with a methacrylic resin (Patent Document 1, Patent Document 2) . If this graft copolymer is used, the impact resistance at room temperature is improved, but a satisfactory level of low temperature impact resistance has not been obtained.

(B) A method in which a graft copolymer obtained by graft polymerization of methyl methacrylate on a silicone copolymer is mixed with a methacrylic resin (Patent Document 3). When this graft copolymer is used, impact resistance at room temperature and low temperature is improved, but it has been desired to further improve warm water whitening property.
US Pat. No. 3,808,180 U.S. Pat. No. 3,843,753 JP-T-2004-529992

  The objective of this invention is providing the thermoplastic resin composition excellent in the weather resistance, transparency, warm water whitening property, and low temperature impact resistance, and its manufacturing method.

  As a result of intensive studies to solve the above problems, the present inventors have found that a special effect can be obtained by using a specific acrylic rubber graft copolymer powder, and to complete the present invention. It came.

That is, the present invention is polymethyl methacrylate resin (A), the and, predominantly poly 2-ethylhexyl consisting acrylate in the presence of a latex of a rubber component composed mainly of Bed chill acrylate monomer to emulsion polymerization to obtain In the thermoplastic resin composition comprising an acrylic rubber graft copolymer (B) obtained by graft polymerization of a vinyl monomer (B-2) to a composite rubber (B-1), The rubber component composed of 2-ethylhexyl acrylate is a ratio (dw / dn) of mass average particle diameter (dw) and number average particle diameter (dn) measured by capillary hydrodynamic flow fractionation (CHDF). Is 1.0 to 1.3, the acrylic rubber graft copolymer (B) is in the form of powder, and the primary particle diameter exceeds 500 nm. Is a thermoplastic resin composition characterized by containing no.

The present invention includes a polymethyl methacrylate based resin (A), the obtained mainly poly 2-ethylhexyl consisting acrylate in the presence of a latex of a rubber component composed mainly of Bed chill acrylate monomer to be emulsion polymerized composite The thermoplastic resin composition according to claim 1, wherein the rubber (B-1) is mixed with an acrylic rubber graft copolymer (B) obtained by graft polymerization of a vinyl monomer (B-2). A method for producing a product, wherein a step for obtaining a rubber component mainly composed of poly-2-ethylhexyl acrylate is (1) a vinyl-based monomer mainly comprising poly-2-ethylhexyl acrylate in water containing a surfactant. Adding a body and producing a pre-emulsion by atomizing using a forced emulsification device; and (2) placing the pre-emulsion in water containing a surfactant. By emulsion polymerization to continue dropping, a method for producing a thermoplastic resin composition having mainly a process of manufacturing a rubber component consisting of poly 2-ethylhexyl acrylate, and.

  According to the present invention, there is provided a thermoplastic resin composition (methacrylic resin composition) excellent in hot water whitening property and low temperature impact resistance without impairing the excellent weather resistance and transparency characteristic of a methacrylic resin. Can be obtained.

In the present invention, the acrylic rubber graft copolymer (B) is obtained predominantly poly 2-ethylhexyl consisting acrylate in the presence of a latex of a rubber component composed mainly of Bed chill acrylate monomer the emulsion polymerization The composite rubber (B-1) is obtained by graft polymerization of a vinyl monomer (B-2).

  Specifically, the rubber component mainly composed of poly-2-ethylhexyl acrylate is 50% to 100% by mass of 2-ethylhexyl acrylate, 100% by mass of the entire rubber component, and other vinyl monomers that can be copolymerized 0%. It is preferable to consist of -50 mass% and the polyfunctional monomer 0-10 mass%. In particular, from the viewpoint of the balance between impact resistance and transparency, the amount of 2-ethylhexyl acrylate is 85 to 95% by mass, the copolymerizable vinyl monomer is 3 to 14.99% by mass, and the amount of the polyfunctional monomer is 0. More preferably, the content is 0.01 to 2% by mass.

  Specific examples of other copolymerizable vinyl monomers include aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene; methacrylic acid esters such as methyl methacrylate and 2-ethylhexyl methacrylate; methyl acrylate and ethyl Various vinyl monomers such as acrylic acid esters such as acrylate and n-butyl acrylate (excluding 2-ethylhexyl acrylate); vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; These may be used alone or in combination of two or more in view of transparency after blending, impact resistance and the like.

  As the polyfunctional monomer, a compound having two or more unsaturated bonds in the molecule is usually used. Specific examples thereof include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, divinylbenzene, and silicone-based crosslinking agents (for example, polyfunctional methacrylic group-modified silicones). Cross-linking agents such as allyl methacrylate, triallyl cyanurate, triallyl isocyanurate, and the like.

  Examples of the method for producing rubber mainly composed of poly-2-ethylhexyl acrylate include emulsion polymerization and forced emulsion polymerization. In particular, forced emulsion polymerization is preferred. In the case of ordinary emulsion polymerization, 2-ethylhexyl acrylate is poor in water solubility, so that a large amount of cullet is likely to occur during polymerization.

  As the forced emulsion polymerization method, (1) a pre-emulsion is prepared by adding a vinyl monomer mainly containing poly 2-ethylhexyl acrylate to water containing a surfactant and atomizing it using a forced emulsifier. (2) A method of producing a rubber component mainly composed of poly-2-ethylhexyl acrylate by continuously dropping the pre-emulsion into water containing a surfactant and subjecting it to emulsion polymerization. By this method, a resin composition having a particle diameter within a narrow range and good transparency can be obtained.

  The rubber component mainly composed of poly 2-ethylhexyl acrylate is a ratio of the mass average particle diameter (dw) to the number average particle diameter (dn) measured by capillary hydrodynamic flow fractionation (CHDF) (dw / Dn) is 1.0 to 1.3. Rubber particles that fall within the range of the ratio (dw / dn) are atomized using a forced emulsification device by adding a vinyl-based monomer mainly containing poly-2-ethylhexyl acrylate to water containing a surfactant. After manufacturing a pre-emulsion by this, it can produce by carrying out the emulsion polymerization of the said pre-emulsion continuously by dripping in the water containing surfactant. Specific measurement conditions are as described in the column of Examples described later.

In the present invention, the composite rubber (B-1) is obtained predominantly poly 2-ethylhexyl consisting acrylate in the presence of a latex of a rubber component composed mainly of Bed chill acrylate monomer to emulsion polymerization. The thermoplastic resin composition produced by this method has good transparency and heat stability.

  Specifically, the rubber component mainly composed of polybutyl acrylate is based on 100% by mass of the entire rubber component, and 50-100% by mass of polybutyl acrylate, 0-50% by mass of other vinyl monomers that can be copolymerized. % And the polyfunctional monomer is preferably 0 to 10% by mass. In particular, it is more preferable that the polybutyl acrylate is 70 to 95% by mass, the copolymerizable v-vinyl monomer is 3 to 29.99% by mass, and the amount of the polyfunctional monomer is 0.01 to 2% by mass. .

  Regarding the ratio of the rubber component mainly composed of poly-2-ethylhexyl acrylate and the rubber component mainly composed of polybutyl acrylate in the composite rubber (B-1), the composite rubber (B-1) is mainly based on 100 parts by mass. 10 to 45 parts by mass of a rubber component composed of poly-2-ethylhexyl acrylate, and 55 to 90 parts by mass of a rubber component mainly composed of polybutyl acrylate are preferable. When either component is extremely small, the impact strength at normal temperature or low temperature tends to decrease.

  In emulsion polymerization, an emulsifier and a dispersion stabilizer are usually used. In the present invention, any known emulsifiers and dispersion stabilizers such as anionic surfactants, nonionic surfactants, and cationic surfactants can be used. These may use 2 or more types together as needed.

  Specific examples of emulsifiers include sulfate-based emulsifiers such as sodium lauryl sulfate, sulfonic acid-based emulsifiers such as sodium alkylbenzene sulfonate and sodium alkyldiphenyl ether sulfonate, sulfosuccinic acid-based emulsifiers, amino group-containing emulsifiers, mono fatty acids and succinic acid. Examples thereof include fatty acid-based emulsifiers.

  The radical polymerization initiator and chain transfer agent used for emulsion polymerization are not particularly limited as long as they are usually used in radical polymerization.

  Specific examples of the radical polymerization initiator include cumene hydroperoxide, t-butyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, di-t-butyl peroxide, t-butyl peroxylaurate, lauroyl. Organic peroxides such as peroxide, succinic acid peroxide, cyclohexanone peroxide, acetylacetone peroxide; inorganic peroxides such as potassium persulfate and ammonium persulfate; 2,2′-azobisisobutyronitrile, 2,2 Examples include azo compounds such as' -azobis-2,4-dimethylvaleronitrile. Of these, organic peroxides or inorganic peroxides are particularly preferred because of their high reactivity. When an organic peroxide or an inorganic peroxide is used, a reducing agent can be used in combination. Specific examples of the reducing agent include ferrous sulfate / glucose / sodium pyrophosphate, ferrous sulfate / dextrose / sodium pyrophosphate, or a mixture of ferrous sulfate / sodium formaldehyde sulfoxylate / ethylenediamine acetate. It is done. Use of a reducing agent in combination is particularly preferred because the polymerization temperature can be lowered.

  The use amount of the radical polymerization initiator is usually 0.005 to 10 parts by mass, preferably 0.01 to 5 parts by mass, more preferably 0.02 to 2 parts by mass with respect to 100 parts by mass of the monomer. is there. The lower limits of these ranges are significant in terms of polymerization rate and production efficiency. The upper limit is significant in terms of increasing the molecular weight of the polymer, impact resistance, and powder characteristics.

  Specific examples of the chain transfer agent include t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, and n-hexyl mercaptan. The chain transfer agent is an optional component and may be used as necessary. When using a chain transfer agent, it is preferable that the usage-amount is 0.001-5 mass parts with respect to 100 mass parts of monomers from the point of expression of impact resistance.

  An acrylic rubber graft copolymer (B) is obtained by polymerizing the vinyl monomer (B-2) in the presence of the composite rubber (B-1).

  Specific examples of the vinyl monomer (B-2) include aromatic vinyl monomers such as styrene, α-methylstyrene and paramethylstyrene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; methacryl Acid; Methacrylate monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate; acrylic acid; methyl acrylate, butyl acrylate, glycidyl acrylate, hydroxyethyl acrylate Acrylic acid ester monomers such as These may be used alone or in combination of two or more in view of compatibility with the thermoplastic resin, the refractive index of the thermoplastic resin composition after blending, and the like.

  About the ratio of both components, composite rubber (B-1) 30-98 mass parts on the basis of a total of 100 mass parts of composite rubber (B-1) and a vinyl-type monomer (B-2), vinyl-type single 2 to 70 parts by mass of the monomer (B-2) is preferable, 50 to 92 parts by mass of the composite rubber (B-1), and 8 to 50 parts by mass of the vinyl monomer (B-2) are more preferable. B-1) 70 to 90 parts by mass and vinyl monomer (B-2) 10 to 30 parts by mass are particularly preferable. The lower limit value of the composite rubber (B-1) and the upper limit value of the vinyl monomer (B-2) in the above ranges are significant in that the impact resistance by the rubber part is sufficiently expressed. Moreover, the upper limit value of the composite rubber (B-1) and the lower limit value of the vinyl monomer (B-2) are improved in compatibility with the thermoplastic resin by the graft portion to ensure impact resistance. it makes sense.

  When the vinyl monomer (B-2) is polymerized in the presence of the composite rubber (B-1), a portion corresponding to a branch of the graft copolymer (polymer of the vinyl monomer) becomes a trunk component (composite). A so-called free polymer obtained by polymerizing only the branch component alone without grafting to (rubber) is also produced as a by-product. That is, a graft copolymer in which free polymers are mixed is obtained. In the present invention, the acrylic rubber graft copolymer (B) includes a mixture of such free polymers.

  When the vinyl monomer (B-2) is emulsion polymerized in the latex of the composite rubber (B-1), a latex of the acrylic rubber graft copolymer (B) is obtained. For example, the latex of the graft copolymer (B) can be recovered as a powder by putting it into hot water in which a coagulant is dissolved, coagulating the graft copolymer (B) and separating it from the aqueous solution.

  Specific examples of the coagulant include inorganic salts such as calcium chloride, magnesium chloride and magnesium sulfate; acids such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, sulfuric acid and hydrochloric acid. It can also be recovered by known methods such as spray drying and freeze coagulation.

  In the present invention, the acrylic rubber graft copolymer (B) is in a powder form and does not contain particles having a primary particle diameter exceeding 500 nm. Similar to the above, such particles can be prepared by continuously dropping the obtained pre-emulsion into water containing a surfactant and subjecting it to emulsion polymerization. When the particle | grains whose primary particle diameter exceeds 500 nm, transparency will fall and an external appearance will be inferior.

  Examples of the method for measuring the primary particle size include particle size distribution measurement by dynamic light scattering (DLS) method, direct particle size measurement by electron microscope, and latex by capillary hydrodynamic flow fractionation (CHDF). Particle size distribution measurement. However, the particle size distribution measurement by the DLS method is simple, but the particle size distribution at 1000 nm or less may not be accurately measured. In direct particle size measurement with an electron microscope, the particle size is accurate but requires a large number of measurements. Therefore, for the measurement of the primary particle size of the graft copolymer (B) in the present invention, the particle size distribution of the latex was measured with CHDF, which allows accurate and simple measurement. In the present invention, the fact that the primary particle diameter does not contain particles exceeding 500 nm means that primary particles of 500 nm or more are not detected in the measurement by CHDF. Specific measurement conditions are as described in the column of Examples described later.

  The mass average particle diameter of the acrylic rubber graft copolymer (B) is preferably 10 nm or more and 500 nm or less, and more preferably 100 nm or more and 400 nm or less from the viewpoint of the balance between transparency and impact resistance.

  In the present invention, the polymethyl methacrylate resin (A) is a resin containing a methyl methacrylate monomer unit, and may contain another monomer unit that can be copolymerized as necessary. As the other copolymerizable monomer, the above-mentioned vinyl monomer (B-2) can be used. The proportion of methyl methacrylate monomer units is preferably 50% by mass or more in 100% by mass of all monomer units of the polymethyl methacrylate resin (A), and the proportion of other monomer units capable of copolymerization is 50%. The mass% or less is preferable. When the proportion of the methyl methacrylate monomer unit is 50% by mass or more, the heat resistance of the obtained molded product is improved.

  The method for producing the polymethyl methacrylate resin (A) is not particularly limited. Various known methods such as suspension polymerization, bulk polymerization, and emulsion polymerization can be applied. The molecular weight of the polymethyl methacrylate resin (A) is not particularly limited, but a mass average molecular weight of 100,000 to 300,000 is preferable.

  In the present invention, the blending ratio of the polymethyl methacrylate resin (A) and the acrylic rubber graft copolymer (B) is based on the total of 100 parts by mass of the component (A) and the component (B). 50-95 mass parts of component, (B) 5-50 mass parts of component are preferable, and (A) component 55-80 mass part and (B) component 20-45 mass part are more preferable especially.

  If necessary, the thermoplastic resin composition of the present invention can be blended with other polymer materials. If necessary, a lubricant, an antiblocking agent, an ultraviolet absorber, a light stabilizer, a plasticizer (phthalate ester, etc.), a stabilizer (2-tert-butyl-6- (3-tert-butyl-2-hydroxy) -5-methylbenzyl) -4-methylphenyl acrylate, etc.), colorants (red-mouthed yellow lead, titanium oxide, etc.), fillers (calcium carbonate, clay, talc, etc.), antioxidants (alkylphenols, organic phosphites) Etc.), UV absorbers (salicylic acid esters, benzotriazoles, etc.), flame retardants (phosphate esters, antimony oxides, etc.), antistatic agents, lubricants, foaming agents, antibacterial and antifungal agents, etc. it can. What is necessary is just to determine these compounding quantities suitably according to the intended purpose. A known method may be used as the blending method. For example, mixing and kneading are performed using a mill roll, a Banbury mixer, a super mixer, a single-screw or twin-screw extruder, and the like.

  The thermoplastic resin composition of the present invention can be molded by a known molding method such as an injection method, a melt extrusion method, or a calendar method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. Prior to the examples, a molding method, a melt characteristic measurement method, and a molded body evaluation method in the examples will be described.

(1) Manufacture of pellets Using a twin screw extruder with a diameter of 30 mm and L / D = 20 at a barrel set temperature of 230 ° C. and a screw rotation speed of 200 rpm, a polymethyl methacrylate resin and an acrylic rubber graft copolymer and other additives Was melt-kneaded to obtain thermoplastic resin composition pellets.

(2) Injection Molding Using the thermoplastic resin composition pellets, injection molding was performed at a mold temperature of 80 ° C. with an injection molding device to mold a test piece for measuring Izod impact strength and a test piece for evaluating transparency.

(3) Izod impact strength Izod impact strength at −10 ° C. was evaluated according to ASTM D256.

(4) Transparency Haze value and total light transmittance were measured according to ASTM D1003.

(5) Water whitening resistance A 50 μm film was prepared, and a sample before the test and a sample after the test immersed in water at 100 ° C. for 2 hours under the condition of a tensile stress of 0.02 MPa and then left at room temperature for 24 hours. The haze value was measured by the method described in the preceding item (4).

(6) Measurement of particle size of latex Using the obtained latex diluted with distilled water as a sample, the particle size was measured using a CHDF2000 particle size distribution meter manufactured by MATEC USA. The measurement conditions were standard conditions recommended by MATEC. That is, using a dedicated particle separation capillary cartridge and carrier liquid, a diluted latex having a concentration of 3% while maintaining a neutral liquidity, a flow rate of 1.4 mL / min, a pressure of 28 MPa, and a temperature of 35 ° C. A 0.1 mL sample was used for the measurement. In addition, as the standard particle size substance, a total of 12 monodisperse polystyrenes having a known particle size manufactured by DUKE in the United States were used within a range of 30 nm to 800 nm. Specifically, the particle size distribution, mass average particle size, and number average particle size of the latex were measured.

Abbreviations of raw materials are as follows.
“2EHA”: 2-ethylhexyl acrylate “ST”: styrene “NBA”: n-butyl acrylate “AMA”: allyl methacrylate “PSSL”: sodium alkyldiphenyl ether disulfonate (trade name Plex SS-L, manufactured by Kao Corporation)
“2F”: sodium lauryl sulfate (trade name Emar 2F, manufactured by Kao Corporation)
“FE”: Ferrous sulfate “EDTA”: Disodium ethylenediaminetetraacetate “RON”: Sodium formaldehyde sulfoxylate “PMP”: Diisopropylbenzene hydroperoxide (trade name Parkmill P, Nippon Shokubai Co., Ltd.)
“MMA”: methyl methacrylate “TBHP”: t-butyl hydroperoxide (trade name Perbutyl H, manufactured by Nippon Shokubai Co., Ltd.)
In the following description, “part” means “part by mass”.

(Production Example 1) Production of graft copolymer (Bi) 2F: To 114 parts of distilled water in which 0.5 part (solid content) was dissolved, 2EHA: 91.0 parts, ST: 8.5 parts and AMA : 0.5 parts of the monomer mixture (b-1) was added, and the mixture was pre-stirred with a homomixer at 10,000 rpm for 5 minutes. Thereafter, the emulsion was emulsified and dispersed with a gorin homogenizer at a pressure of 20 MPa to obtain a pre-emulsion.

  A 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, additional monomer port, and thermometer was charged with 0.4 parts of 2F (in terms of solid content) and 60 parts of water, and the system was filled with nitrogen. While replacing, the temperature was raised to 60 ° C., and water: 5.8 parts, FE: 0.00002 parts, EDTA: 0.0006 parts, RON: 0.24 parts were added. 5 minutes after the addition, PMP: 0.5 part added to the pre-emulsion was added dropwise over 90 minutes while maintaining the temperature at 60 ° C., and the polymerization reaction was advanced by holding for another 90 minutes after the completion of the addition. A poly 2-ethylhexyl acrylate acrylic rubber latex was obtained.

  The polymerization rate of this poly-2-ethylhexyl acrylate acrylic rubber latex was 99.8%, and the amount of scale generated during the polymerization was 0.01%. The latex particles have a mass average particle diameter (dw) of 60 nm, a number average particle diameter (dn) of 55 nm, a ratio (dw / dn) of 1.09, and a ratio of particles having a particle diameter exceeding 500 nm is 0. It was mass%.

  Next, 20 parts of the poly-2-ethylhexyl acrylate acrylic rubber latex (in terms of solid content) was charged into the same 5-neck flask as above, and water: 48.7 parts and PSSL: 0.5 parts were added. The temperature was raised to 60 ° C. under a nitrogen stream, and water: 1.0 part, FE: 0.001 part, EDTA: 0.003 part, RON: 0.3 part were added. Thereafter, a mixture (b-2) consisting of NBA: 56.1 parts, ST: 11.5 parts, AMA: 1.4 parts and PMP: 0.3 parts was added dropwise over 180 minutes. The polymerization reaction was advanced by holding for a minute to obtain an acrylic composite rubber latex.

  Subsequently, a mixture (b-3) composed of MMA: 11 parts and TBHP: 0.06 parts was dropped over 30 minutes at 60 ° C. over this acrylic composite rubber latex, and the mixture was held for 60 minutes after the completion of the dropping. As a result, the graft polymerization reaction was advanced to obtain an acrylic rubber graft copolymer latex. Latex particles had a dw of 120 nm and a dn of 115 nm, and the proportion of particles having a particle diameter exceeding 500 nm was 0% by mass.

  100 parts of this acrylic rubber graft copolymer latex (in terms of solid content) is dropped into 200 parts of hot water containing 1.5% by mass of aluminum sulfate, solidified, separated, washed, and washed at 75 ° C. for 16 hours. It dried and obtained the powdery acrylic rubber graft copolymer (Bi).

(Production Example 2) Production of Graft Copolymer (B-ii) Except that the amount of 2F charged in the 5-neck flask to which the pre-emulsion was dropped was changed from 0.4 part to 0.03 part (solid content conversion). An acrylic rubber graft copolymer latex was produced in the same manner as in Production Example 1. The particles of poly-2-ethylhexyl acrylate acrylic rubber latex had a dw of 210 nm, a dn of 200 nm, a dw / dn of 1.05, and the proportion of particles having a particle diameter exceeding 500 nm was 0% by mass. The acrylic rubber graft copolymer latex particles had a dw of 365 nm and a dn of 360 nm, and the proportion of particles having a particle diameter exceeding 500 nm was 0% by mass.

  This acrylic rubber graft copolymer latex was separated and dried by the same method as in Production Example 1 to obtain a powdery acrylic rubber graft copolymer (B-ii).

(Production Example 3) Production of Graft Copolymer (B-iii) PSSL: To 195 parts distilled water in which 1 part (solid content) was dissolved, the same monomer mixture (b-1) as in Example 1 was added, A pre-emulsion was produced under the same conditions as in Example 1.

  This pre-emulsion was transferred to a separable flask equipped with a condenser and a stirring blade, heated with nitrogen substitution and mixing and stirring, and when the temperature was raised to 50 ° C., 0.5 part of TBHP was added. Subsequently, when the temperature was raised to 60 ° C., a mixture of FE 0.002 part, EDTA 0.006 part, RON 0.26 part and distilled water 5 part was added, and the polymerization reaction was advanced by maintaining at 60 ° C. for 5 hours. A poly-2-ethylhexyl acrylate acrylic rubber latex was obtained.

  The polymerization rate of this poly-2-ethylhexyl acrylate acrylic rubber latex was 99.9%. The latex particles had a dw of 170 nm, a dn of 120 nm, a dw / dn of 1.42, and a proportion of particles having a particle diameter exceeding 500 nm was 18% by mass.

  Next, 20 parts of the poly-2-ethylhexyl acrylate acrylic rubber latex (in terms of solid content) was charged into the same 5-neck flask as in Example 1, and 3.5 parts (solid content) of PSSL was added. Furthermore, distilled water was added so that the amount of distilled water in the flask was 195 parts. Thereafter, at 60 ° C. under the same conditions as in Example 1, the polymerization reaction was advanced by adding FE, EDTA, RON, and dropping and holding the mixture (b-2) to obtain an acrylic composite rubber latex.

  Subsequently, the same mixture (b-3) as in Example 1 was added dropwise to this acrylic composite rubber latex at 70 ° C. over 15 minutes, and the graft polymerization reaction was advanced by holding for 4 hours after the completion of the addition. An acrylic rubber graft copolymer latex was obtained. Latex particles had a dw of 210 nm and a dn of 185 nm, and the proportion of particles having a particle diameter exceeding 500 nm was 4% by mass.

  This acrylic rubber graft copolymer latex was separated and dried in the same manner as in Production Example 1 to obtain a powdery acrylic rubber graft copolymer (B-iii).

Production Example 4 Production of Graft Copolymer (B-iv) The composition of the monomer mixture (b-1) for producing the pre-emulsion was 2EHA: 99.5 parts, AMA: 0.5 parts, 2F : 0.5 parts (in terms of solid content), except that the composition of the mixture (b-2) was changed to NBA: 67.6 parts, AMA: 1.4 parts, PMP: 0.3 parts, In the same manner as in Production Example 3, an acrylic rubber graft copolymer (B-iv) was produced.

  The particles of the poly-2-ethylhexyl acrylate acrylic rubber latex had a dw of 200 nm, a dn of 100 nm, a dw / dn of 2, and a ratio of particles having a particle diameter exceeding 500 nm was 22% by mass. Moreover, dw of the particle | grains of acrylic rubber graft copolymer latex was 170 nm, dn was 200 nm, and the ratio of the particle | grains whose particle diameter exceeds 500 nm was 6 mass%.

(Production Example 5) Production of Graft Copolymer (Bv) According to Example 1 of JP-A-2005-171141, a multilayer structure polymer not containing 2EHA is produced, coagulated and recovered, and a powdered graft A copolymer (Bv) was obtained. The acrylic rubber latex particles had a dw of 80 nm and a dn of 75 nm, and the proportion of particles having a particle diameter exceeding 500 nm was 0% by mass. The rubber graft copolymer latex particles had a dw of 150 nm and a dn of 135 nm, and the proportion of particles having a particle diameter exceeding 500 nm was 0% by mass.

(Examples 1 and 2, Comparative Examples 1 to 3)
After blending the raw materials (A), (B), and (C) in the blending amounts shown in Table 1, and producing pellets with an extruder, injection molding is performed, the above-mentioned various test pieces are produced, and physical properties are evaluated. It was. The results are shown in Table 1.

The symbols in the table mean the following materials.
(A): Polymethylmethacrylate resin (trade name Acripet SV, manufactured by Mitsubishi Rayon Co., Ltd.)
(B-1) to (B-5): Graft copolymer produced in Production Examples 1 to 5 (C): Antioxidant (trade name ADK STAB 2112, manufactured by Asahi Denka Kogyo Co., Ltd.).

  As can be seen from the comparison with Comparative Example 1, in Examples 1 and 2, the particle size distribution of the rubber component is narrow, and the graft copolymer (B) does not contain particles having a primary particle diameter of more than 500 nm. It is good. Further, as can be seen from the comparison with Comparative Example 2, Examples 1 and 2 have good transparency with no decrease in transparency due to the difference in refractive index depending on the composition. Further, as can be seen from the comparison with Comparative Example 3, Examples 1 and 2 contain 2EHA components, so that the impact strength at low temperature is excellent.

  Therefore, the thermoplastic resin compositions of Examples 1 and 2 can be effectively used for various uses such as building materials, molded members for automobiles, and lighting members. On the other hand, the thermoplastic resin compositions of Comparative Examples 1 to 3 are limited in use because any of the physical properties is insufficient.

Claims (2)

Polymethyl methacrylate resin (A), and
The predominantly poly 2-ethylhexyl consisting acrylate in the presence of a latex of a rubber component composed mainly of Bed chill acrylate monomer composite rubber obtained by emulsion polymerization (B-1), the vinyl monomer (B -2) is an acrylic rubber graft copolymer (B) obtained by graft polymerization
In a thermoplastic resin composition comprising:
The rubber component mainly composed of poly 2-ethylhexyl acrylate is a ratio of the mass average particle diameter (dw) to the number average particle diameter (dn) measured by capillary hydrodynamic flow fractionation (CHDF) (dw / Dn) is 1.0 to 1.3,
A thermoplastic resin composition characterized in that the acrylic rubber graft copolymer (B) is in a powder form and does not contain particles having a primary particle diameter exceeding 500 nm. A polymethyl methacrylate-based resin (A), the main composite rubber obtained poly 2-ethylhexyl consisting acrylate in the presence of a latex of a rubber component composed mainly of Bed chill acrylate monomer to be emulsion polymerization (B-1 2) and the acrylic rubber graft copolymer (B) obtained by graft polymerization of the vinyl monomer (B-2). In order to obtain a rubber component mainly composed of poly-2-ethylhexyl acrylate,
(1) A step of producing a pre-emulsion by adding a vinyl monomer mainly containing poly-2-ethylhexyl acrylate to water containing a surfactant and atomizing using a forced emulsification device; and
(2) A step of producing a rubber component mainly composed of poly-2-ethylhexyl acrylate by continuously dropping the pre-emulsion into water containing a surfactant to cause emulsion polymerization.
The manufacturing method of the thermoplastic resin composition which has this.