JP5583884B2 - Thermoplastic resin composition - Google Patents

Description

  The present invention relates to a thermoplastic resin composition. More specifically, the present invention relates to a thermoplastic resin composition containing a polylactic acid resin having an excellent balance of impact strength, heat resistance, workability, and appearance uniformity.

In recent years, as an environmental problem on a global scale, the future of petroleum resources due to increased use of petrochemical products has been threatened. For example, polylactic acid resin is a resin made of lactic acid obtained from plant corn and potatoes as a raw material, and is known as an environmentally friendly resin that does not use petroleum as a raw material. However, the polylactic acid resin has the disadvantages that it is inferior in notched impact strength and heat resistance.
On the other hand, ABS resin has excellent physical property balance and molding processability and is used in a wide range of fields.
The raw material depends on petroleum resources. The following conventional technologies have been proposed to compensate for these disadvantages, but they cannot satisfy all of the physical properties of impact strength, heat resistance, workability, and uniformity of appearance, and improvements are desired. It is rare.
JP 2000-327847 A JP 2004-269720 A JP-A-2005-171204 JP 2006-137908 A JP 2006-161024 A JP 2007-63368 A JP 2007-126535 A

  The present invention has been made to solve the above-mentioned problems, and provides a thermoplastic resin composition containing a polylactic acid resin having an excellent balance of impact strength, heat resistance, workability, and appearance uniformity. It is intended.

That is, the present invention comprises polylactic acid resin (L) 5 to 50 parts by weight, rubber-containing graft copolymer (G) 10 to 60 parts by weight, (meth) acrylic ester polymer (M) 15 to 50 parts by weight, α-methylstyrene-acrylonitrile copolymer (A) comprising 5 to 70 parts by weight of a thermoplastic resin composition (however, the total of (L), (G), (M), (A) is 100 parts by weight).

  The thermoplastic resin composition according to the present invention has an excellent balance of impact strength, heat resistance, processability, and uniformity of appearance, and particularly as an environmentally friendly material that can contribute to the suppression of petroleum resource consumption. It can be widely used in the field of building materials and sanitary.

Hereinafter, the thermoplastic resin composition of the present invention will be described in detail.
In the present invention, the polylactic acid resin constitutes an essential component of the thermoplastic resin composition. Examples of the commercially available polyresin include, but are not limited to, product names: Lacia, manufactured by Mitsui Chemicals, Inc., and product names: Terramac, manufactured by Unitika Ltd.

The rubber-containing graft copolymer (G) in the present invention is obtained by polymerizing a vinyl monomer to a rubber-like polymer. Examples of the rubber-like polymer include polybutadiene, polyisoprene, and butadiene. Diene rubber such as styrene copolymer, isoprene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-isoprene-styrene copolymer, polychloroprene, ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene Examples thereof include copolymers, ethylene-butene-1-nonconjugated diene copolymers, acrylic rubbers such as polybutyl acrylate, polyorganosiloxane rubbers, and composite rubbers composed of two or more of these rubbers. 1 type, or 2 or more types can be used. Among these, conjugated diene rubber is particularly preferable from the viewpoint of impact strength development.
Examples of the vinyl monomer suitably used for the production of the rubber-containing graft copolymer include a styrene monomer, a vinyl cyanide monomer, and a (meth) acrylic acid ester monomer.
Examples of the styrene monomer include styrene, α-methylstyrene, paramethylstyrene, bromostyrene, and the like, and one or two or more types can be used. In particular, styrene and α-methylstyrene are preferable.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile. Particularly preferred is acrylonitrile.
Examples of the (meth) acrylic acid ester monomer include methyl acrylate and methyl acrylate. Particularly preferred is methyl methacrylate.
Moreover, it is also possible to use an unsaturated acid monomer such as maleic anhydride and dimethyl maleate, a maleimide monomer such as N-phenylmaleimide, N-cyclohexylmaleimide, and the like together with the vinyl monomer. .
The composition ratio of each component constituting the rubber-containing graft copolymer is not particularly limited, but preferably 5 to 70% by weight of a rubbery polymer and a styrene monomer, a vinyl cyanide monomer, It is 30 to 95% by weight of a vinyl monomer selected from (meth) acrylic acid ester monomers.
The polymerization method of the rubber-containing graft copolymer is not particularly limited, and can be produced by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or a combination thereof, but is stable over time in a high temperature and high humidity environment. From the viewpoint of maintaining the property, the content of the alkali metal contained in the rubber-containing graft copolymer is preferably 0.01% by weight or less.

  Examples of the monomer suitably used for the production of the (meth) acrylic acid ester polymer (M) in the present invention include methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, etc., and particularly methyl methacrylate alone or methyl It is preferable to use methacrylate in combination with mainly methyl acrylate. Also, if necessary, other monomers may be used in combination with other monomers such as styrene monomers and vinyl cyanide monomers, but these other monomers in the (meth) acrylate polymer Is preferably less than 20% by weight, more preferably 10% by weight.

The composition ratio of the α-methylstyrene-acrylonitrile copolymer (A) in the present invention is particularly preferably 60 to 80% by weight of α-methylstyrene and 20 to 40% by weight of acrylonitrile.
Moreover, there is no restriction | limiting in particular also about the polymerization method of (alpha) -methylstyrene acrylonitrile copolymer (A), It can manufacture by emulsion polymerization, suspension polymerization, block polymerization, solution polymerization, or these combination.

The thermoplastic resin composition of the present invention comprises a polylactic acid resin (L) 5 to 70 parts by weight, a rubber-containing graft copolymer (G) 10 to 60 parts by weight, and a (meth) acrylic acid ester polymer (M) 1 To 50 parts by weight, α-methylstyrene-acrylonitrile copolymer (A) 5 to 84 parts by weight (however, the total of (L), (G), (M), (A) is 100 weights) Part.)
When the blending ratio of the polylactic acid resin (L) is less than 5 parts by weight, the environmental burden that most of the raw material depends on petroleum resources is not reduced, and when it exceeds 70 parts by weight, the heat resistance is lowered. Preferably it is 10-60 weight part, More preferably, it is 15-50 weight part.
When the blending ratio of the rubber-containing graft copolymer (G) is less than 10 parts by weight, the impact strength is inferior, and when it exceeds 60 parts by weight, workability and heat resistance are lowered. Preferably it is 10-55 weight part, More preferably, it is 15-55 weight part.
If the blending ratio of the (meth) acrylic acid ester polymer (M) is less than 1 part by weight, the uniformity of the appearance is poor, and if it exceeds 50 parts by weight, the heat resistance and impact strength are lowered. Preferably it is 10-45 weight part, More preferably, it is 15-40 weight part.
When the blending ratio of the α-methylstyrene-acrylonitrile copolymer (A) is less than 5 parts by weight, the heat resistance is poor, and when it exceeds 84 parts by weight, the impact strength is lowered. Preferably it is 10-70 weight part, More preferably, it is 10-60 weight part.

  In addition to the above components, the thermoplastic resin composition according to the present invention includes stabilizers, pigments, dyes, reinforcements at the time of resin mixing and molding depending on the purpose, as long as the physical properties are not impaired. Agents (talc, mica, clay, glass fiber, etc.), colorants (carbon black, titanium oxide, etc.), UV absorbers, antioxidants, lubricants, mold release agents, plasticizers, antistatic agents, inorganic and organic antibacterials Known additives such as an agent can be blended.

  Examples of the method for mixing the thermoplastic resin composition in the present invention include a method using a known kneader such as a Banbury mixer or an extruder. Further, there is no limitation on the mixing order, and it is possible to mix the remaining components after mixing two to three components in advance, as well as batch mixing of the four components.

〔Example〕
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these.
Unless otherwise specified,% and parts are based on weight.

Polylactic acid resin (L)
LACEA H-400 manufactured by Mitsui Chemicals, Inc. was used as the polylactic acid resin (L).

Preparation of rubber-containing graft copolymers G1 to G3 Rubber-containing graft copolymer G1: In a pressure-resistant polymerization reactor made of stainless steel, 21.9 parts of pure water, 1.0 part of potassium oleate, and sodium naphthalenesulfonate were added under reduced pressure. Formalin condensate 0.5 part, sodium hydroxide 0.15 part, butadiene-styrene copolymer latex (styrene content 10 wt%, gel content 85 wt%, weight average particle size 430 nm) as rubber-like polymer 65 parts in solids, 0.25 part of t-dodecyl mercaptan, 0.08 part of glucose and 0.002 part of ferrous sulfate were charged and heated to 67 ° C. with sufficient stirring, and then t-butyl hydroperoxide 0.08 part was charged and polymerization was started at 67 ° C. Immediately after the start, a monomer mixture of 27 parts of styrene and 8 parts of acrylonitrile was continuously added over 2 hours. When the polymerization conversion rate exceeded 63%, 0.04 part of t-butyl hydroperoxide was added, and the reaction temperature was adjusted. The temperature was raised to 72 ° C and the reaction was continued for 2 hours. After confirming that the polymerization conversion rate exceeded 97%, the temperature in the tank was cooled to 40 ° C or lower. The obtained latex-like rubber-containing graft copolymer was poured into a large amount of methanol, precipitated, poured into a 100-mesh stainless steel wire mesh, and then washed with an appropriate amount of methanol and then with a large amount of pure water. Thereafter, methanol remaining under reduced pressure was removed and dried in a hot air oven at 85 ° C. until the water content became 1% by weight or less to obtain a powdery rubber-containing graft copolymer G1.
The obtained rubber-containing graft copolymer G1 was incinerated and then dissolved in an acid, and the alkali metal content was measured by ICP emission spectroscopy and atomic absorption spectroscopy. As a result, it was 0.002% by weight.

Rubber-containing graft copolymer G2: In stainless steel pressure-resistant polymerization reactor, 65.7 parts pure water, 1.5 parts potassium oleate, 0.8 parts formalin condensate of sodium naphthalenesulfonate under reduced pressure, potassium hydroxide 0.20 parts, butadiene-acrylonitrile copolymer latex (acrylonitrile content 2% by weight, gel content 90% by weight, weight average particle size 370 nm) as a rubbery polymer, 40 parts by solids, t-dodecyl mercaptan 0 20 parts, 0.05 parts of glucose and 0.003 part of ferrous sulfate were added and the temperature was raised to 65 ° C. with sufficient stirring, followed by 0.07 parts of t-butyl hydroperoxide and polymerization at 65 ° C. Started. Immediately after the start, a monomer mixture of 30 parts of styrene, 10 parts of acrylonitrile and 20 parts of methyl methacrylate was continuously converted over 4 hours, and when the conversion rate exceeded 65%, 0.06 part of cumene hydroperoxide was charged and reacted. The temperature was raised to 70 ° C. and the reaction was continued for 2 hours. After confirming that the polymerization conversion rate exceeded 97%, the temperature in the tank was cooled to 40 ° C. or lower. The obtained latex-like rubber-containing graft copolymer was poured into a large amount of methanol, precipitated, poured into a 100-mesh stainless steel wire mesh, and then washed with an appropriate amount of methanol and then with a large amount of pure water. Thereafter, the remaining methanol was removed under reduced pressure, and it was dried in a hot air oven at 85 ° C. until the water content became 1% by weight or less to obtain a powdery rubber-containing graft copolymer G2.
The obtained rubber-containing graft copolymer G2 was incinerated, dissolved in an acid, and the alkali metal content was measured by ICP emission spectroscopy and atomic absorption spectroscopy. As a result, it was 0.004% by weight.

Rubber-containing graft copolymer G3: A continuous block polymerization apparatus in which two 10-liter complete mixing tanks were connected in series to a plug flow tower type reaction tank having a volume of 15 liters was used. The plug flow tower type reaction vessel constitutes the particle formation step, the first complete mixing vessel as the second reactor constitutes the particle size adjustment step, and the third reactor constitutes the post-polymerization step.
In a plug flow column reactor, 22 parts by weight of ethylbenzene, 49.1 parts by weight of styrene, 16.4 parts by weight of acrylonitrile, 12.5 parts by weight of Nipol NS320S manufactured by Nippon Zeon Co., Ltd. as a diene rubbery polymer, t-dodecyl A raw material consisting of 0.20 part by weight of mercaptan, 0.045 part by weight of 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane was prepared, and this raw material was added to a three-stage stirred polymerization tank row The monomer was polymerized by continuously feeding the reactor at 10 kg / hr. The polymerization solution was led from the third-stage tank to a separation and recovery step comprising a preheater and a decompression chamber.
The resin from the recovery step was subjected to an extrusion step to obtain a rubber-containing graft copolymer G3 as granular pellets. When the composition analysis of the pellets was performed by pyrolysis chromatography, the diene rubber component was 25% by weight, the styrene monomer component was 56% by weight, and the acrylonitrile monomer component was 19% by weight.
The obtained rubber-containing graft copolymer G3 was incinerated and then dissolved in an acid, and the alkali metal content was measured by ICP emission spectroscopy and atomic absorption spectrometry. As a result, it was 0.0005% by weight.

Production of (meth) acrylic acid ester copolymers M1 and M2 (Meth) acrylic acid ester copolymer M1: Two 10 liter complete mixing tanks are connected in series to a 15 liter plug flow tower type reaction tank. A connected continuous bulk polymerization apparatus was used.
20 parts by weight of ethylbenzene, 72 parts by weight of methyl methacrylate, 8 parts by weight of methyl acrylate, 0.15 parts by weight of t-dodecyl mercaptan, 1,1-bis (t-butylperoxy) 3, 3, A raw material consisting of 0.050 part by weight of 5-trimethylcyclohexane was prepared, and this raw material was continuously fed to a three-stage stirred polymerization tank train reactor at 12 kg / hour to polymerize the monomer. The polymerization solution was led from the third-stage tank to a separation and recovery step comprising a preheater and a decompression chamber.
The resin from the recovery step was subjected to an extrusion step to obtain a (meth) acrylate copolymer M1 as granular pellets. When the composition analysis of the pellets was performed by pyrolysis chromatography, the methyl methacrylate monomer component was 90% by weight and the methyl acrylate monomer component was 10% by weight.

(Meth) acrylic ester copolymer M2: A continuous bulk polymerization apparatus in which two 10 liter complete mixing tanks were connected in series to a 15 liter plug flow column reactor.
In a plug flow tower type reaction vessel, ethylbenzene 25 parts by weight, methyl methacrylate 67.5 parts by weight, methyl acrylate 1.5 parts by weight, styrene 3 parts by weight, acrylonitrile 3 parts by weight, t-dodecyl mercaptan 0.20 parts by weight, A raw material consisting of 0.042 parts by weight of 1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane was prepared, and this raw material was continuously supplied to a three-stage stirred polymerization tank train reactor at 10 kg / h. The monomer was polymerized by feeding. The polymerization solution was led from the third-stage tank to a separation and recovery step comprising a preheater and a decompression chamber.
The resin from the recovery step was subjected to an extrusion step to obtain a (meth) acrylate copolymer M1 as granular pellets. The composition of the pellet was analyzed by pyrolysis chromatography. As a result, 90% by weight of the methyl methacrylate monomer component, 2% by weight of the methyl acrylate monomer component, 4% by weight of the styrene monomer component, and 4% of the acrylonitrile monomer component. % By weight.

Production of α-methylstyrene-acrylonitrile copolymers A1 to A2 α-methylstyrene-acrylonitrile copolymer A1: Two 10-liter complete mixing tanks were connected in series to a 15-liter plug flow column reactor. A continuous bulk polymerization apparatus was used.
In a plug flow column type reaction vessel, 25 parts by weight of ethylbenzene, 52.5 parts by weight of α-methylstyrene, 22.5 parts by weight of acrylonitrile, 0.10 parts by weight of t-dodecyl mercaptan, 1,1-bis (t-butylperoxy ) A raw material consisting of 0.090 parts by weight of 3,3,5-trimethylcyclohexane was prepared, and this raw material was continuously fed to a three-stage stirred polymerization tank train reactor at 10 kg / h to polymerize the monomer. went. The polymerization solution was led from the third-stage tank to a separation and recovery step comprising a preheater and a decompression chamber.
The resin from the recovery step was subjected to an extrusion step to obtain α-methylstyrene-acrylonitrile copolymer A1 as granular pellets. The composition analysis of the pellets was carried out by pyrolysis chromatography. As a result, the α-methylstyrene monomer component was 70% by weight and the acrylonitrile monomer component was 30% by weight.

  α-methylstyrene-acrylonitrile copolymer A2: In a pressure-resistant polymerization reactor made of stainless steel, 155 parts of pure water under reduced pressure, 3.0 parts of potassium rosinate as an emulsifier, 0.7 parts of formalin condensate of sodium naphthalenesulfonate, 0.08 parts of sodium hydroxide, 75 parts of α-methylstyrene, 25 parts of acrylonitrile and 0.18 parts of t-dodecyl mercaptan were added and the mixture was heated to 72 ° C. with sufficient stirring, and then charged with 0.5 parts of potassium persulfate. Polymerization was started at 72 ° C. When the polymerization conversion rate exceeded 63%, the reaction temperature was raised to 77 ° C. and the reaction was continued. After confirming that the polymerization conversion rate exceeded 97%, the temperature in the tank was cooled to 40 ° C. or less. The obtained α-methylstyrene-acrylonitrile copolymer was salted out using an aqueous magnesium sulfate solution, and after washing, dried in a hot air oven at 90 ° C. until the water content became 1% by weight or less. A methylstyrene-acrylonitrile copolymer A2 was obtained.

[Examples 1-5, Comparative Examples 1-6]
Polylactic acid resin (L), rubber-containing graft copolymer (G1 to G3), (meth) acrylic acid ester copolymer (M1 to M2), α-methylstyrene-acrylonitrile copolymer (A1 to A2) ) At a blending ratio shown in Table 1, melt mixed at 220 ° C. to 250 ° C. using a 30 mm twin screw extruder, pelletized, and various physical properties were evaluated by preparing various test pieces with an injection molding machine. did. Each evaluation method is shown below, and the evaluation results are summarized in Table 1.

Evaluation method of each physical property Workability: Melt index was measured at 220 ° C. and 10 kg based on ISO 1133. The unit is g / 10 minutes. Based on the measurement results obtained, relative classification was performed as follows.
◎ (excellent): 40 or more ○ (good): 20 or more to less than 40 △ (slightly inferior): 5 or more to less than 20 × (defect): less than 5

Impact strength: Based on ISO 179, a Charpy impact value with a notch was measured. The unit is kJ / m2.
Based on the measurement results obtained, relative classification was performed as follows.
◎ (Excellent): 15 or more ○ (Good): 10 or more and less than 15 △ (Slightly inferior): 5 or more and less than 10 × (Bad): Less than 5

Heat resistance: Based on ISO 75, the deflection temperature under load of 1.8 MPa was measured. The unit is ° C.
Based on the measurement results obtained, relative classification was performed as follows.
◎ (excellent): 75 ° C or higher ○ (good): 70 ° C or higher to lower than 75 ° C △ (slightly inferior): 65 ° C or higher to lower than 70 ° C × (defect): lower than 65 ° C

Appearance uniformity: The test piece for measuring DuPont impact with two gates is judged with the naked eye,
The relative classification was as follows.
◎ (Excellent): No weld line is observed and surface gloss is good.
○ (Good): No clear weld line is observed, but the gloss at the center of the test piece is slightly uneven.
Δ (slightly inferior): Weld line is observed and gloss is not uniform.
X (defect): A clear weld line is recognized.

As described above, the present invention provides a thermoplastic resin composition having an excellent balance of impact strength, heat resistance, workability, and uniformity of appearance, and includes the vehicle field, home appliance field, building material field, and sanitary. It can be widely used in fields.
It is also an environmentally friendly material that can contribute to the reduction of petroleum resource consumption.

Claims (4)

5 to 50 parts by weight of polylactic acid resin (L), 10 to 60 parts by weight of rubber-containing graft copolymer (G), 15 to 50 parts by weight of (meth) acrylate polymer (M), α-methylstyrene A thermoplastic resin composition comprising 5 to 70 parts by weight of the acrylonitrile copolymer (A) (provided that the total of (L), (G), (M) and (A) is 100 parts by weight. .)
  The thermoplastic resin composition according to claim 1, wherein the α-methylstyrene-acrylonitrile copolymer (A) is a copolymer comprising 60 to 80% by weight of α-methylstyrene and 20 to 40% by weight of acrylonitrile.   The thermoplastic resin composition according to claim 1 or 2, wherein the rubber-containing graft copolymer (G) is a conjugated diene rubber-containing graft copolymer.   The thermoplastic resin composition according to any one of claims 1 to 3, wherein the rubber-containing graft copolymer (G) has an alkali metal content of 0.01% by weight or less.