JP2008106090A - Resin composition containing polylactic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition containing a polylactic acid giving a molded article having excellent impact resistance and applicable in the field of materials such as a protective plate of a liquid crystal panel and an illuminated advertising display. <P>SOLUTION: The resin composition containing a polylactic acid and having a polylactic acid resin content of ≥20 wt.% is produced by adding ≥0.5 pt.wt. of an acrylic copolymer having a weight-average molecular weight (Mw) of ≥800,000 and free from rubber components to 100 pts.wt. of a mixed resin composition containing a polylactic acid resin and one or both of an ABS resin and a polycarbonate resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polylactic acid-containing resin composition suitable for obtaining a molded product that requires impact resistance, such as a protective plate for a liquid crystal panel and a sign for lighting.

  Polylactic acid resin is a plant-derived resin obtained from plants such as corn, and unlike conventional petroleum resins such as polystyrene resin, polypropylene resin, polyvinyl chloride resin, polyethylene resin, etc., prevention of petroleum resource depletion It is said that it has effects such as suppression of carbon dioxide emission, and is expected as a material to replace petroleum resin. In particular, a polylactic acid-containing resin composition containing 20% by weight or more of a polylactic acid resin is being applied to various fields of use as reducing the environmental burden.

  However, since the polylactic acid resin is inferior in impact resistance as compared with existing petroleum resins, the polylactic acid-containing resin composition containing 20% by weight or more of polylactic acid resin is inferior in impact resistance. It is difficult to apply to the field of materials that require impact resistance, such as a protective plate and a sign for lighting, and the improvement is desired from an early stage.

  In general, in order to improve the impact resistance of petroleum-based thermoplastic resins, methods of blending other petroleum-based thermoplastic resins that are superior in impact resistance to the petroleum-based thermoplastic resins have been studied. Kaihei 06-80842 (Patent Document 1) describes a rubbery heavy material such as acrylonitrile-butadiene-styrene copolymer (hereinafter referred to as ABS resin) having higher impact resistance than vinyl chloride resin and styrene resin. JP-A-2002-97361 (Patent Document 2) suggests a method of blending a coalescence and a method of blending a polycarbonate resin.

  Moreover, the method of improving impact resistance is generally performed by blending the additive containing the rubber component marketed as an impact resistance improver.

  In addition, a method for improving impact resistance by graft copolymerization has been studied, and JP 2003-286396 (Patent Document 3) suggests a polymer obtained by grafting a methyl methacrylate resin or the like to a rubbery polymer. Yes.

Therefore, a similar study has been made for polylactic acid resin, and Japanese Patent Application Laid-Open No. 2006-137908 (Patent Document 4) shows an example in which impact resistance is improved by blending ABS resin with polylactic acid resin. JP 2006-199743 (Patent Document 5) shows an example in which impact resistance is improved by blending a polycarbonate resin with a polylactic acid resin, and JP-A 2003-286396 (Patent Document 6) contains a rubber component in the polylactic acid resin. An example in which impact resistance is improved by blending a multilayer structure polymer has been reported. However, in any case, the impact resistance cannot be improved sufficiently, and it is not satisfactory in the material field.
JP 06-80842 JP 2002-97361 JP 2003-286396 A JP 2006-137908 A JP 2006-199743 A JP 2003-286396 A

  An object of the present invention is to provide a polylactic acid-containing resin composition capable of obtaining a molded article having excellent impact resistance, which can be applied to a material field such as a protective plate of a liquid crystal panel or a sign for lighting. .

  As a result of diligent efforts by the present inventors, in a polylactic acid-containing resin composition containing 20% by weight or more of a polylactic acid resin, the polylactic acid resin and a mixture containing either or both of an ABS resin and a polycarbonate resin It was found that a resin composition having very high impact resistance can be obtained by adding an acrylic copolymer containing no rubber component to the resin composition, and the present invention has been completed.

  That is, in the invention according to claim 1, in the polylactic acid-containing resin composition containing 20% by weight or more of the polylactic acid resin, the polylactic acid resin and either or both of the ABS resin and the polycarbonate resin are contained. The polyresin characterized in that an acrylic copolymer having a weight average molecular weight (Mw) of 800,000 or more and no rubber component is added by 0.5 parts by weight or more with respect to 100 parts by weight of the mixed resin composition. The gist of the present invention is a lactic acid-containing resin composition.

  In the invention according to claim 2, the acrylic copolymer containing no rubber component is a copolymer of a styrene monomer and a (meth) acrylic acid ester monomer or a (meth) acrylic acid ester unit. The polylactic acid-containing resin composition according to claim 1, which is at least one selected from the group consisting of copolymers of monomers.

  In the invention according to claim 3, the copolymer of the (meth) acrylic acid ester monomers is a copolymer of methyl methacrylate and butyl methacrylate or a copolymer of methyl methacrylate and butyl acrylate. The gist of the polylactic acid-containing resin composition according to claim 2, which is one of coalesced ones.

  According to the present invention, in a polylactic acid-containing resin composition containing 20% by weight or more of a polylactic acid resin, a mixed resin composition containing the polylactic acid resin and / or both of an ABS resin and a polycarbonate resin. Polylactic acid containing excellent impact resistance by adding 0.5 parts by weight or more of an acrylic copolymer having a weight average molecular weight (Mw) of 800,000 or more and no rubber component to 100 parts by weight Resin compositions can be obtained, and the molded products can be applied to applications that require impact resistance, such as protective plates such as liquid crystal panels, thin products such as cards, and lighting signs that could not be applied until now. Therefore, it can contribute to prevention of oil resource depletion and carbon dioxide emission control.

  The polylactic acid resin according to the present invention is obtained by dehydration condensation of L-lactic acid, D-lactic acid, LD-lactic acid, or a mixture thereof, or obtained by ring-opening polymerization of lactide of lactic acid. The content ratio of L-polylactic acid and D-polylactic acid is not limited.

  Moreover, you may copolymerize other copolymerization components other than lactic acid. As a monomer used as a copolymerization component with lactic acid, as hydroxycarboxylic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid Etc.

  Examples of the aliphatic cyclic ester include glycolide, lactide, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, and lactones substituted with various groups such as a methyl group.

  Examples of the dicarboxylic acid include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid. Examples of the polyhydric alcohol include aromatic polyhydric alcohols such as bisphenol / ethylene oxide addition reaction products, Aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylolpropane, neopentyl glycol, ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, etc. Is mentioned.

  The ABS resin used in the present invention includes a thermoplastic graft copolymer obtained by graft polymerization of a vinyl cyanide compound and an aromatic vinyl compound to a diene rubber component, and a copolymer of the vinyl cyanide compound and the aromatic vinyl compound. A mixture with coalescence. As the diene rubber component forming this ABS resin, for example, a rubber having a glass transition temperature of −30 ° C. or lower such as polybutadiene, polyisoprene and styrene-butadiene copolymer is used, and the proportion thereof is 100% by weight of the ABS resin component. The content is preferably 5 to 80% by weight, more preferably 8 to 50% by weight, and particularly preferably 10 to 30% by weight. As the vinyl cyanide compound grafted on the diene rubber component, acrylonitrile is particularly preferably used.

  As the aromatic vinyl compound grafted on the diene rubber component, styrene and α-methylstyrene are particularly preferably used. The ratio of the component grafted to the diene rubber component is preferably 95 to 20% by weight, more preferably 92 to 50% by weight, and particularly preferably 90 to 70% by weight in 100% by weight of the resin component. Further, the vinyl cyanide compound is preferably 5 to 50% by weight and the aromatic vinyl compound is preferably 95 to 50% by weight with respect to 100% by weight of the total amount of the vinyl cyanide compound and the aromatic vinyl compound. Further, methyl (meth) acrylate, ethyl acrylate, maleic anhydride, N-substituted maleimide and the like can be mixed and used for a part of the components grafted to the diene rubber component, and the content ratio thereof is in the ABS resin component. What is 15 weight% or less is preferable. Furthermore, conventionally known various initiators, chain transfer agents, emulsifiers and the like can be used as necessary.

  In the ABS resin of the present invention, the rubber particle diameter is preferably 0.1 to 5.0 μm, more preferably 0.2 to 3.0 μm, and particularly preferably 0.3 to 1.5 μm. As the distribution of the rubber particle diameter, both a single distribution and a rubber particle having a plurality of peaks can be used, and the rubber particles have a single phase in the morphology. Alternatively, it may have a salami structure by containing an occluded phase around the rubber particles.

  Further, it is well known that the ABS resin contains a vinyl cyanide compound and an aromatic vinyl compound that are not grafted to the diene rubber component, and the ABS resin of the present invention is also generated during such polymerization. It may contain a free polymer component.

  The ratio of the grafted vinyl cyanide compound and the aromatic vinyl compound is preferably 20 to 200%, more preferably 20 to 70%, expressed as a graft ratio (% by weight) with respect to the diene rubber component. Is.

  The ABS resin may be produced by any one of bulk polymerization, suspension polymerization, and emulsion polymerization, but is preferably bulk polymerization. This is because the ABS resin obtained by bulk polymerization does not basically contain impurities derived from an emulsifier and the like, and therefore causes less rust generation. The copolymerization method may be copolymerized in a single stage or in multiple stages.

  Moreover, what blended the vinyl resin polymer obtained by copolymerizing an aromatic vinyl compound and a vinyl cyanide component separately to the ABS resin obtained by this manufacturing method can also be used preferably.

  The polycarbonate resin used in the present invention is not particularly limited. For example, an aromatic homo- or copolycarbonate obtained by reacting an aromatic dihydric phenol compound with phosgene or a carbonic acid diester can be used. An aromatic polycarbonate is mentioned.

  Examples of the aromatic dihydric phenol compound include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4- Hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-diphenyl) butane, 2 , 2-bis (4-hydroxy-3,5-diethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-diethylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane or the like can be used, and these can be used alone or as a mixture.

  The molecular weight of the aromatic polycarbonate resin is not particularly limited, but the viscosity average molecular weight is preferably 10,000 to 60,000, and more preferably 15,000 to 50,000.

  The polylactic acid-containing resin composition of the present invention is composed of the above-mentioned polylactic acid resin and a mixed resin composition containing either or both of ABS resin and polycarbonate resin, and 100 parts by weight of this mixed resin composition On the other hand, an acrylic copolymer having a weight molecular weight (Mw) of 800,000 or more and containing no rubber component is added by 0.5 parts by weight or more. The content ratio of the polylactic acid resin in this polylactic acid-containing resin composition is 20% by weight or more. When the content of the polylactic acid resin is less than 20% by weight, it is not suitable in terms of effects such as prevention of petroleum resource depletion and suppression of carbon dioxide emission.

  Examples of the acrylic copolymer containing no rubber component used in the present invention include a copolymer of a styrene monomer and a (meth) acrylate ester monomer, a styrene monomer and an acrylate ester monomer. Copolymers of monomers, copolymers of (meth) acrylate monomers, copolymers of acrylate monomers, (meth) acrylate monomers and acrylate esters Examples thereof include copolymers of monomeric monomers. Among these, a copolymer of a styrene monomer and a (meth) acrylic acid ester monomer or a copolymer of (meth) acrylic acid ester monomers is preferable. By selecting these copolymers, the impact resistance of the polylactic acid-containing resin composition can be improved more effectively.

  Examples of (meth) acrylic acid ester monomers include alkyl groups (including cycloalkyl groups) such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and isobornyl methacrylate. (Meth) acrylic acid alkyl ester monomers having 1 to 18 carbon atoms, (meth) acrylic acid aryl ester monomers such as phenyl methacrylate, (meth) acrylic acid aralkyl esters such as benzyl methacrylate Monomers and the like can be mentioned, and these monomers can be used alone or in admixture of two or more. Furthermore, the copolymer of (meth) acrylic acid ester monomers is either a copolymer of methyl methacrylate and butyl methacrylate, or a copolymer of methyl methacrylate and butyl acrylate. Is preferred. By selecting these copolymers, the impact resistance of the polylactic acid-containing resin composition can be improved more effectively.

  Here, the acrylic copolymer according to the present invention needs to contain no rubber component. When the rubber component is not contained, good impact resistance can be exhibited when added to the polylactic acid-containing resin. Examples of the rubber component include acrylic rubber, butadiene rubber, silicone rubber, urethane rubber, and the like. Although an acrylic copolymer that does not contain a rubber component is added to the polylactic acid-containing resin composition, the reason why it can exhibit good impact resistance is not understood in detail, but the polylactic acid resin, the ABS resin, It is thought that it may act as a compatibilizing agent for improving fluidity or compatibility when both or either of the polycarbonate resins is mixed. On the other hand, it is considered that an acrylic copolymer containing a rubber component cannot sufficiently function as a compatibilizing agent.

  The acrylic copolymer containing no rubber component in the present invention needs to have a weight average molecular weight (Mw) of 800,000 or more from the viewpoint of ensuring impact resistance. When the weight average molecular weight (Mw) of the acrylic copolymer containing no rubber component is less than 800,000, since the melting temperature is low, the polylactic acid resin, the ABS resin and / or the polycarbonate resin are either Since it becomes difficult to mix at the time of melt molding with the contained mixed resin composition, sufficient impact resistance cannot be obtained. The upper limit of the weight average molecular weight (Mw) of the acrylic copolymer that does not contain a rubber component is not particularly limited, and can be used within a manufacturable range.

  The addition amount of the acrylic copolymer containing no rubber component is 0.5 parts by weight or more with respect to 100 parts by weight of the mixed resin composition. If the amount of the acrylic copolymer not containing the rubber component is less than 0.5 parts by weight, sufficient impact resistance cannot be obtained.

  In the polylactic acid-containing resin composition of the present invention, various additives can be blended within a range in which the polylactic acid resin is contained in an amount of 20% by weight or more, if necessary. Specific examples include known antioxidants, ultraviolet absorbers, lubricants, plasticizers, stabilizers, mold release agents, antistatic agents, colorants, flame retardants, glass fibers, carbon fibers, and anti-drip agents. .

  Hereinafter, the details of the polylactic acid-containing resin composition of the present invention will be described by way of examples.

The resins used are as follows.
<Polylactic acid resin>
Product name Lacia H400 manufactured by Mitsui Chemicals, Inc.
<ABS resin (1)>
Product name SANAC ST-55 made by Nippon A & L Co., Ltd.
<ABS resin (2)>
Nippon A & L Co., Ltd. Product name Clarastic SRE
<Polycarbonate resin (1)>
Product name Iupilon E2000 manufactured by Mitsubishi Engineering Plastics Co., Ltd.
<Polycarbonate resin (2)>
Product name Iupilon H3000 manufactured by Mitsubishi Engineering Plastics Co., Ltd.
<Acrylic copolymer having a weight average molecular weight (Mw) of 7,000,000 and no rubber component>
Kaneka Corporation Product Name Kane Ace PA PA-60
<Acrylic copolymer having a weight average molecular weight (Mw) of 800,000 and no rubber component>
Kaneka Corporation Product Name Kane Ace PA PA-10
<Acrylic copolymer having a weight average molecular weight (Mw) of 100,000 and no rubber component>
Kaneka Corporation Product Name Kane Ace PA PA-100
<Multilayer structure polymer containing rubber component>
Product name manufactured by Mitsubishi Rayon Co., Ltd. Metablen C-223

<Example 1>
Weight average molecular weight (Mw) is 800,000 with respect to 100 parts by weight of a mixed resin composition comprising 25% by weight of polylactic acid resin, 25% by weight of ABS resin (1), and 50% by weight of polycarbonate resin (1), rubber 10 parts by weight of an acrylic copolymer containing no components was added, and extrusion molding was carried out using a single screw extruder having a screw diameter of 40 mm and L / D = 32 to prepare a sheet having a thickness of 3.0 mm.

<Example 2>
Weight average molecular weight (Mw) is 800,000 with respect to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin, 30% by weight of ABS resin (1) and 20% by weight of polycarbonate resin (2), and rubber A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 0.5 part by weight of the acrylic copolymer containing no component was added.

<Example 3>
The weight average molecular weight (Mw) is 7,000,000 with respect to 100 parts by weight of the mixed resin composition comprising 80% by weight of polylactic acid resin, 10% by weight of ABS resin (1) and 10% by weight of polycarbonate resin (1). A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 5 parts by weight of an acrylic copolymer containing no rubber component and no rubber component was added.

<Example 4>
The weight average molecular weight (Mw) is 800,000 with respect to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin, 20% by weight of ABS resin (2) and 30% by weight of polycarbonate resin (2), and rubber A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 10 parts by weight of an acrylic copolymer containing no component was added.

<Example 5>
An acrylic copolymer having a weight average molecular weight (Mw) of 800,000 and no rubber component with respect to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin and 50% by weight of ABS resin (2). A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 5 parts by weight was added.

<Example 6>
An acrylic copolymer having a weight average molecular weight (Mw) of 800,000 and no rubber component with respect to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin and 50% by weight of polycarbonate resin (1). A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 5 parts by weight was added.

Comparative example

<Comparative Example 1>
Weight average molecular weight (Mw) is 800,000 with respect to 100 parts by weight of a mixed resin composition comprising 10% by weight of polylactic acid resin, 40% by weight of ABS resin (1) and 50% by weight of polycarbonate resin (1), and rubber A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 8 parts by weight of an acrylic copolymer containing no component was mixed.

<Comparative example 2>
Weight average molecular weight (Mw) is 800,000 with respect to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin, 20% by weight of ABS resin (1) and 30% by weight of polycarbonate resin (1), and rubber A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 0.3 part by weight of an acrylic copolymer containing no component was mixed.

<Comparative Example 3>
The weight average molecular weight (Mw) is 7,000,000 per 100 parts by weight of the mixed resin composition comprising 50% by weight of polylactic acid resin, 20% by weight of ABS resin (2) and 30% by weight of polycarbonate resin (2). A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 0.1 part by weight of an acrylic copolymer containing no rubber component was added.

<Comparative Example 4>
The weight average molecular weight (Mw) is 100,000 with respect to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin, 20% by weight of ABS resin (2), and 30% by weight of polycarbonate resin (2), and rubber. A sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1 except that 10 parts by weight of an acrylic copolymer containing no component was added.

<Comparative Example 5>
5 parts by weight of a multilayer structure polymer containing a rubber component was added to 100 parts by weight of a mixed resin composition comprising 50% by weight of polylactic acid resin, 30% by weight of ABS resin (1) and 20% by weight of polycarbonate resin (2). Otherwise, a sheet having a thickness of 3.0 mm was prepared in the same manner as in Example 1.

<Izod impact strength>
The Izod impact strength of the obtained sheet was measured. In addition, evaluation was performed according to ASTM D256, the thing of 100 J / m or more was made into (circle), and the following were made into x.

<Prevention of oil resource depletion / CO2 emission control effect>
The effect of preventing oil resource depletion / suppressing carbon dioxide emissions is indicated by ○ and ×. In the polylactic acid-containing resin composition, the content of the polylactic acid resin was 20% by weight or more, and that of less than 20% by weight was rated as x.

  From the results of Table 1 and Table 2, the acrylic copolymer having a polylactic acid resin, ABS resin, polycarbonate resin, and weight average molecular weight (Mw) of 800,000 or more as shown in the scope of the present invention and containing no rubber component In Examples 1 to 6, which are polylactic acid-containing resin compositions containing a coalescence, good results are shown in impact resistance and oil resource depletion prevention / carbon dioxide emission suppression effect. On the other hand, in Comparative Examples 1-5 which deviate from the technical scope of this invention, it was inferior to either an impact resistance or a petroleum resource depletion prevention / carbon dioxide emission suppression effect.

Claims (3)

  In a polylactic acid-containing resin composition containing 20% by weight or more of a polylactic acid resin, a mixed resin composition comprising a polylactic acid resin, and / or an acrylonitrile-styrene-butadiene copolymer and / or a polycarbonate resin Polylactic acid-containing resin characterized in that an acrylic copolymer having a weight average molecular weight (Mw) of 800,000 or more and not containing a rubber component is added to 100 parts by weight of a product. Composition.   The acrylic copolymer containing no rubber component is a group consisting of a copolymer of a styrene monomer and a (meth) acrylate monomer or a copolymer of (meth) acrylate monomers. The polylactic acid-containing resin composition according to claim 1, which is at least one selected from the group consisting of:   The copolymer of the (meth) acrylic acid ester monomers is either a copolymer of methyl methacrylate and butyl methacrylate or a copolymer of methyl methacrylate and butyl acrylate. 2. The polylactic acid-containing resin composition according to 2.