JP2009132776A - Thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain improvement of balance of impact strength, heat-resistance, processability and uniformness of appearance of a thermoplastic resin composition containing a poly-lactic acid resin. <P>SOLUTION: The thermoplastic resin composition comprises 5-70 pts.wt. of the poly-lactic acid resin (L), 10-60 pts.wt. of a non-conjugated diene based rubber-containing graft copolymer (G), 1-50 pts.wt. of a (meth)acrylate based hard polymer (M) and 5-84 pts.wt. of an α-methylstyrene-acrylonitrile copolymer (A) comprising 60-80 wt.% of an α-methylstyrene and 20-40 wt.% of acrylonitrile (provided that total of (L), (G), (M) and (A) is 100 pts.wt.). <P>COPYRIGHT: (C)2009,JPO&INPIT

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, a 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 an excellent balance of physical properties and moldability and is used in a wide range of fields, but the raw material depends on petroleum resources. The following prior arts have been proposed for the purpose of compensating both of these drawbacks, but they cannot satisfy all physical properties such as impact strength, heat resistance, workability, and uniformity of appearance, and improvements are desired. ing.
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 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 the purpose.

  That is, the present invention relates to polylactic acid resin (L) 5 to 70 parts by weight, non-conjugated diene rubber-containing graft copolymer (G) 10 to 60 parts by weight, (meth) acrylic acid ester hard polymer (M) 1 -50 parts by weight, α-methylstyrene-acrylonitrile copolymer (A) 5 to 84 parts by weight thermoplastic resin composition (however, (L), (G), (M), ( The sum of 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 non-conjugated diene rubber-containing graft copolymer (G) in the present invention is obtained by polymerizing a vinyl monomer on a non-conjugated diene rubber-like polymer. Examples of the polymer include ethylene-propylene rubber polymers such as ethylene-propylene copolymers, ethylene-propylene-nonconjugated diene copolymers, and ethylene-butene-1-nonconjugated diene copolymers, and acrylic rubber-like heavy polymers. A coalescence is exemplified, but an acrylic rubber-like polymer is particularly preferable.
The acrylic rubbery polymer is 90 to 99% by weight of (meth) acrylic acid ester of alkyl alcohol excluding methyl alcohol, 1 to 10% by weight of monomers having a plurality of vinyl groups, and other copolymerizable It is composed of 0 to 9% by weight of a vinyl monomer. Examples of (meth) acrylic acid esters of alkyl alcohol excluding methyl alcohol include ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. In particular, butyl acrylate is preferred. The monomers having a plurality of vinyl groups include (meth) acrylic acid esters of polyhydric alcohols such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol-1,6-dimethacrylate, allyl acrylate, allyl. (Meth) acrylic acid esters of allyl alcohol such as methacrylate, divinylbenzene and the like.
Examples of other copolymerizable monomers constituting the rubbery polymer include styrene monomers, vinyl cyanide monomers, methyl (meth) acrylate monomers, and the like. Among the styrene monomers, styrene and α-methylstyrene are particularly preferable, and among the vinyl cyanide monomers, acrylonitrile is particularly preferable.

Examples of vinyl monomers used for graft polymerization of the non-conjugated diene rubber-containing graft copolymer (G) include styrene monomers, vinyl cyanide monomers, and methyl (meth) acrylate monomers. Etc.
Examples of the styrenic monomer include styrene, α-methylstyrene, paramethylstyrene, bromostyrene, and the like, and one or more of them 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.
The (meth) acrylic acid methyl monomers are 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 ratio of the rubber-like polymer constituting the non-conjugated diene rubber-containing graft copolymer (G) and the vinyl monomer used for the graft polymerization is not particularly limited, but is preferably a rubber-like polymer. 5 to 70% by weight and 30 to 95% by weight of a vinyl monomer selected from a styrene monomer, a vinyl cyanide monomer, and a methyl (meth) acrylate monomer.
The polymerization method of the non-conjugated diene rubber-containing graft copolymer (G) is not particularly limited and can be produced by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or a combination thereof. From the viewpoint of maintaining stability over time in a high humidity environment, the content of 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 ester hard polymer (M) in the present invention include methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, etc., and particularly methyl methacrylate alone or The combined use of methyl methacrylate mainly with methyl acrylate and the like is preferable. Ethyl acrylate, butyl acrylate, and the like can be used in a small amount, but it is desirable that the monomer constituting the (meth) acrylic ester polymer (M) is limited to 10% by weight or less from the viewpoint of heat resistance. In addition, if necessary, other monomers such as styrene monomers and vinyl cyanide monomers may be used in combination, but the monomer constituting the (meth) acrylate hard polymer (M). Among the monomers, the copolymerization ratio of other monomers is preferably less than 20% by weight, more preferably 10% by weight.
Moreover, there is no restriction | limiting in particular also about the polymerization method of a (meth) acrylic-ester type hard polymer (M), It can manufacture by emulsion polymerization, suspension polymerization, block polymerization, solution polymerization, or these combination.

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 5 to 70 parts by weight of a polylactic acid resin (L), 10 to 60 parts by weight of a non-conjugated diene rubber-containing graft copolymer (G), and a (meth) acrylic acid ester-based hard heavy. 1 to 50 parts by weight of the union (M) and 5 to 84 parts by weight of the α-methylstyrene-acrylonitrile copolymer (A) (however, (L), (G), (M), (A) Is 100 parts by weight.)
If the blending ratio of the polylactic acid resin (L) is less than 5 parts by weight, the environmental load that most of the raw materials depend on petroleum resources is not reduced, and if it exceeds 70 parts by weight, impact strength and heat resistance are reduced. Preferably it is 10-60 weight part, More preferably, it is 15-55 weight part.
When the blending ratio of the non-conjugated diene 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 15-50 weight part.
If the blending ratio of the (meth) acrylic ester hard 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 is lowered. Preferably it is 10-45 weight part, More preferably, it is 10-40 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. Agent (talc, mica, clay, glass fiber, etc.), colorant (carbon black, titanium oxide, etc.), UV absorber, antioxidant, flame retardant, lubricant, mold release agent, plasticizer, antistatic agent, inorganic and Known additives such as organic antibacterial agents 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 rubbery polymers 1-2 Rubbery polymer 1: A formalin condensate of 130 parts of pure water, 0.8 parts of potassium alkenyl succinate and sodium naphthalenesulfonate in a pressure-resistant polymerization reactor made of stainless steel under reduced pressure. 2 parts, potassium hydroxide 0.05 parts, butyl acrylate 93 parts, methyl methacrylate 3 parts, allyl methacrylate 2 parts, t-dodecyl mercaptan 0.18 parts, glucose 0.08 parts, ferrous sulfate 0.005 parts After charging and heating to 53 ° C. while stirring, 0.3 part of potassium persulfate was charged and polymerization was started at 53 ° C. The reaction temperature was raised to 63 ° C. over 210 minutes from the start of polymerization, and the reaction was continued. When the polymerization conversion rate exceeded 67%, 0.02 part of glucose and 0.05 part of t-butyl hydroperoxide were added. The temperature was raised to 70 ° C. and the reaction was continued. After confirming that the polymerization conversion rate exceeded 98%, the temperature in the tank was cooled to 35 ° C. or less, and the polymer particles were enlarged by the phosphoric acid agglomeration method to obtain a latex-like rubbery polymer 1. The solid content concentration was 38.0% by weight, pH 9.7, and the average particle size was 290 m.

  Rubbery polymer 2: In a stainless steel pressure-resistant polymerization reactor, 135 parts of pure water, 1.1 parts of potassium alkenyl succinate, 0.2 parts of formalin condensate of sodium naphthalenesulfonate, 0.03 potassium hydroxide Part, butyl acrylate 92 parts, styrene 5 parts, allyl methacrylate 3 parts, t-dodecyl mercaptan 0.25 part, glucose 0.15 part, ferrous sulfate 0.005 part Then, 0.1 part of t-butyl hydroperoxide was charged and polymerization was started at 62 ° C. The reaction was continued while maintaining the temperature at 62 ° C, and when the polymerization conversion rate exceeded 65%, 0.02 part of glucose and 0.05 part of cumene hydroperoxide were added, and the temperature was raised to 70 ° C to react. Continued. After confirming that the polymerization conversion rate exceeded 98%, the temperature in the tank was cooled to 35 ° C. or less, and the polymer particles were enlarged by the phosphoric acid agglomeration method to obtain a latex-like rubber-like polymer 2. The solid content concentration was 37.2% by weight, pH 9.4, and the average particle size was 380 nm.

Preparation of rubber-containing graft copolymers G1 to G2 Rubber-containing graft copolymer G1: In a stainless steel pressure-resistant polymerization reactor, 33.9 parts of pure water, 0.3 parts of potassium rosinate, and 1. 0 parts, 0.5 parts of formalin condensate of sodium naphthalenesulfonate, 0.15 parts of sodium hydroxide, 65 parts of solid polymer 1 in solid content, 0.08 parts of glucose, 0.004 parts of ferrous sulfate Was added, and the temperature was raised to 63 ° C. with sufficient stirring. Then, 0.08 part of t-butyl hydroperoxide was added and polymerization was started at 63 ° C. Immediately after the start, a mixture of 27 parts of styrene, 8 parts of acrylonitrile and 0.25 part of t-dodecyl mercaptan was continuously added over 2 hours. When the polymerization conversion exceeded 65%, 0.04 part of t-butyl hydroperoxide was added. The reaction temperature was raised to 70 ° C. and the reaction was continued for 1 hour or longer. 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 150-mesh stainless steel wire mesh, and then washed with an appropriate amount of methanol and then with a large amount of pure water. Then, it was dried until the water content became 1% by weight or less under reduced pressure to obtain a powdery rubber-containing graft copolymer G1.
The obtained rubber-containing graft copolymer G1 was incinerated, dissolved in pure water, and the alkali metal content was measured by ICP method and atomic absorption method. The result was 0.003% by weight.

Rubber-containing graft copolymer G2: In a stainless steel pressure-resistant polymerization reactor, 47.2 parts pure water, 1.5 parts potassium oleate, 0.8 parts formalin condensate of sodium naphthalenesulfonate under reduced pressure, potassium hydroxide After adding 0.20 part, 55 parts of rubbery polymer 2 in solid content, 0.10 part of glucose, and 0.005 part of ferrous sulfate and heating to 65 ° C. with sufficient stirring, cumene hydroperoxide 0.07 part was charged and polymerization was started at 65 ° C. Immediately after the start, a mixture of 30 parts of styrene, 5 parts of methyl methacrylate, 10 parts of acrylonitrile and 0.20 part of t-dodecyl mercaptan was continuously added over 3 hours. When the polymerization conversion exceeded 66%, t-butyl hydroper 0.05 parts of oxide was added, the reaction temperature was raised to 70 ° C., and the reaction was continued for 2 hours or more. After confirming that the polymerization conversion rate exceeded 98%, the temperature in the tank was cooled to 40 ° C. or less. The obtained latex-like rubber-containing graft copolymer was poured into a large amount of methanol, precipitated, poured into a 150-mesh stainless steel wire mesh, and then washed with an appropriate amount of methanol and then with a large amount of pure water. Then, it was dried until the water content became 1% by weight or less under reduced pressure to obtain a powdery rubber-containing graft copolymer G2.
The obtained rubber-containing graft copolymer G2 was incinerated, dissolved in pure water, and the alkali metal content was measured by ICP method and atomic absorption method. The result was 0.004% by weight.

Production of (meth) acrylic ester hard polymers M1 and M2 (meth) acrylic ester hard polymer M1: Two 10 liter complete mixing tanks in series in a 15 liter plug flow column reactor 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 discharged from the recovery step was subjected to an extrusion step to obtain a (meth) acrylate hard 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 hard polymer M2: A continuous bulk 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.
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 process was subjected to an extrusion process to obtain a (meth) acrylate hard copolymer M2 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 80 ° C. until the water content became 1% by weight or less. A methylstyrene-acrylonitrile copolymer A2 was obtained.

[Examples 1 to 4, Comparative Examples 1 to 6]
Polylactic acid resin (L), rubber-containing graft copolymer (G1 to G2), (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 230 ° C. to 250 ° C. using a 30 mm twin screw extruder, pelletized, and various physical properties were evaluated by making 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. Unit is kJ ^{/ m} 2.
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

Appearance uniformity: DuPont impact measurement test pieces having gates at two locations were judged with the naked eye, and were classified relative to each other 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 appearance uniformity, and is used in the vehicle field, home appliance field, building material field, and sanitary field. Can be used widely.
It is also an environmentally friendly material that can contribute to the reduction of petroleum resource consumption.

Claims (4)

  5 to 70 parts by weight of a polylactic acid resin (L), 10 to 60 parts by weight of a non-conjugated diene rubber-containing graft copolymer (G), 1 to 50 parts by weight of a (meth) acrylate hard polymer (M), α-methylstyrene-acrylonitrile copolymer (A) comprising 5 to 84 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 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-like polymer of the non-conjugated diene rubber-containing graft copolymer (G) is an acrylic rubber-like polymer.   The thermoplastic resin composition according to any one of claims 1 to 3, wherein the non-conjugated diene rubber-containing graft copolymer (G) has an alkali metal content of 0.01% by weight or less.