JP2007002211A - Polylactic acid resin composition and method for producing polylactic acid resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-containing resin composition obtained by modifying an originally fragile polylactic acid contributing to reduction of the amount of fossil fuel used and the discharge amount of carbon dioxide and enabling reduction of the waste amount by utilizing decomposition by microorganisms so as to have properties excellent in toughness, flexibility, ductility and impact resistance and to provide a method for producing the resin composition. <P>SOLUTION: The resin composition is obtained by melting and kneading a mixture composed of (A) 30-99 wt.% polylactic acid with (B) 70-1 wt.% copolymer having a functional group having reactivity with the polylactic acid. The resin composition has a structure in which the reactive copolymer (B) is discontinuously dispersed as a disperse phase in the range from 10 μm average particle diameter to 10 nanometer average particle diameter into a continuous phase composed of the polylactic acid (A). In the profile of X-ray diffraction of the resin composition, broad hallow diffraction figure derived from an amorphous substance is predominant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polylactic acid resin composition and a method for producing the polylactic acid resin composition.

In recent years, the development of plant-derived resins has been actively promoted.
Polylactic acid resin (also referred to as PLA), which is a representative of these plant-derived resins, has advantages such as excellent transparency, rigidity, and processability compared to other general-purpose plastics, but it is pointed out as a problem It is said that the resin lacks mechanical strength when used as a film.

  Then, the improvement which makes a resin strong is produced by producing | generating a copolymer with another polyester compound etc., and performing extending | stretching operation. And it becomes a physical property which improves mechanical strength by biaxial stretching and can be used as a film. This is a heat-shrinkable film, and it is known that dimensional stability can be imparted by subsequent heat treatment (Patent Document 1, Patent Document 2 and Patent Document 3). Those disclosed in these publications are biaxially stretched films by the tenter method, and improvements have been made in terms of tensile breaking strength and tensile breaking elongation, but only films having inferior tear strength have been obtained.

Also, an easily tearable biaxially stretched film of a blend comprising a polylactic acid polymer and a crystalline aliphatic polyester (Patent Document 4), and an easily tearable polylactic acid based film comprising polylactic acid and polyethylene terephthalate and / or polyethylene isophthalate. Although there exists an axial stretched film (patent document 5), only the film which is excellent in tearing linearity and hand cutting property and inferior in tearing strength is obtained.
Further, a stretched film excellent in dimensional stability, high-speed cutting properties and impact properties (eg, an aliphatic polyester obtained by polycondensation of polylactic acid, aliphatic dicarboxylic acid and aliphatic diol (glass transition point _Tg of 10 ° C. or less)) Similarly, there is a film (Patent Document 7) having a high tear strength measured by the JIS-K-7128 method and a high impact strength measured by the ASTM-D 1709-91 method.
Also, a biaxially stretched film containing a polylactic acid polymer and an aliphatic-aromatic copolymer polyester, with a constant heat shrinkage difference in the machine direction and the transverse direction being less than a certain value, and drawing at 100 ° C. or less A film is also known (Patent Document 8).
Furthermore, there is an invention (Patent Document 9) in which impact resistance can be improved by mixing segmented polyester, natural rubber, and styrene-butadiene copolymer with polylactic acid. In general, compatibility between these materials and polylactic acid is known. However, when the impact resistance is improved but blend unevenness is likely to occur, not only the appearance is inferior but also the mechanical strength is not stable.
Heating and plasticizing natural rubber and synthetic rubber, adding polylactic acid powder, kneading at a temperature below the melting point of polylactic acid to form a mixture, and further kneading at a temperature above the melting point (Patent Document 10) is complicated. Requires a lot of manipulation.

  As mentioned above, the patent described in the previous section is a system that does not react with another polymer added to polylactic acid, but melts while reacting between different polymers in order to improve moldability. A kneading method (reactive processing method) has also been reported. For example, there are an example in which epoxidized isoprene is added as an additive to polylactic acid (Patent Document 11), and a method in which polyurethane or an epoxy group-containing thermoplastic elastomer is melt-mixed (Patent Document 12). Here, attempts have been made to improve the melting characteristics, mechanical characteristics, impact resistance, appearance of the molded product, etc., but the impact strength has been improved only by a factor of at most. Furthermore, a composition comprising polylactic acid and an epoxidized diene block copolymer, and a composition obtained by adding polycaprolactone to this system have also been reported (Patent Document 13), and mechanical properties and biodegradability have been studied. In order to improve the impact resistance, the amount of the diene block copolymer has to be increased, but it has been reported that the biodegradability decreases. Similarly, there is a report (Patent Document 14) on mechanical properties including impact strength and biodegradability in a system in which a modified olefin compound is added to polylactic acid. In these reports, although the composition is limited, the structure of the composition that largely controls these physical properties (for example, the size of the dispersed phase in the composition and the crystal structure of the composition) is mentioned. Absent.

  In addition, examples of polylactic acid-based compositions comprising three components with reaction, such as polylactic acid, polyacetal resin, and impact-resistant agent (Patent Documents 15 and 16), polylactic acid, aliphatic polyesters other than polylactic acid, and modified olefins An example composed of a compound (Patent Document 17) has been reported.

  However, a polymer composition composed of polylactic acid and an epoxy group-containing resin has a uniform composition, but has characteristics that can withstand use in terms of tensile strength, elongation at break and impact strength. It has not been obtained yet. Against this background, materials with improved physical properties such as tensile strength, elongation at break and impact strength are desired.

  With regard to polymer compositions and resins containing polylactic acid, which is a biodegradable material, the tensile strength, elongation at break and flexibility are good in spite of the inherently weak polylactic acid. It was considered impossible to expect a material with the property of being destructive. An invention was desired to challenge this point.

Japanese Patent Laid-Open No. 06-23836 Japanese Patent Application Laid-Open No. 07-207041 Japanese Patent Application Laid-Open No. 07-267553 JP 2000-198913 A JP 2001-64413 A JP 2003-286354 A JP 2003-292642 A JP 2003-342391 A Japanese Patent No. 2725870 JP 2004-143315 A JP 2000-95898 A JP 2002-37995 A JP 2000-219803 A JP 09-316310 A JP 2003-277594 A JP 2003-286400 A JP 2001-123055 A

  An object of the present invention is to modify a polylactic acid-containing resin composition having a property not inferior to that of a general-purpose petroleum-derived resin by modifying inherently fragile polylactic acid into a material excellent in toughness, flexibility, ductility, and impact resistance. Is to provide.

The present inventors diligently researched on the above problems and obtained the following knowledge.
A mixture of 30 to 99% by weight of polylactic acid (A) and 70 to 1% by weight (B) of a copolymer having a functional group reactive with the polylactic acid is melt-kneaded to obtain polylactic acid (A). In which the reactive copolymer (B) has a structure in which the reactive copolymer (B) is discontinuously dispersed as a dispersed phase having an average particle size ranging from 10 microns to 10 nanometers, and is amorphous in the X-ray diffraction profile. When obtaining a resin composition characterized by a dominant halo diffraction pattern derived from a porous material, the composition may be a material with improved toughness, flexibility, ductility and impact resistance. When the physical properties of the resin composition of the present invention are compared with those of polylactic acid alone, the impact value of the resin composition of the present invention is remarkably improved (in the range of about 2 to 20 times) while maintaining the thermal stability, and the brittleness to ductility ( The elongation at break should be 5% to 200%) Heading, it has led to the completion of the present invention.

According to the present invention, the following inventions are provided.
(1) From a resin composition obtained by melt-kneading 30 to 99% by weight (A) of polylactic acid and 70 to 1% by weight (B) of a copolymer having a functional group reactive with the polylactic acid The resin composition has a structure in which a reactive copolymer (B) is discontinuously dispersed as a dispersed phase having an average particle size in the range of 10 microns to 10 nanometers in a continuous phase composed of polylactic acid (A). And a broad halo diffraction pattern derived from an amorphous substance is dominant in the X-ray diffraction profile.
(2) The resin composition as described in (1), wherein the polylactic acid (A) has a weight average molecular weight of 5,000 to 1,000,000.
(3) The copolymer (B) having a functional group reactive with polylactic acid is a copolymer having an epoxy group, wherein the copolymer has an epoxy group (1) or (2) Resin composition.
(4) The copolymer (B) having an epoxy group contains 0.1 to 30% by weight of an unsaturated carboxylic acid glycidyl ester unit and / or an unsaturated glycidyl ether unit (1) to (3) ).
(5) The resin composition according to any one of (1) to (4), wherein the copolymer (B) having an epoxy group contains a structure of an olefin compound.
(6) The copolymer (B) having an epoxy group comprises (a) 60 to 99% by weight of ethylene units, and (b) 0.1 to 20 of unsaturated carboxylic acid glycidyl ester units and / or unsaturated glycidyl ether units. The resin composition according to any one of (1) to (5), which is an epoxy group-containing ethylene copolymer comprising 0% to 40% by weight of (c) an ethylenically unsaturated ester compound. .
(7) The resin composition according to any one of (1) to (6), wherein the copolymer (B) having an epoxy group has a heat of fusion of less than 3 J / g.
(8) The resin composition according to any one of (1) to (7), wherein the copolymer (B) having an epoxy group has a Mooney viscosity in the range of 3 to 70.
(9) The resin composition according to any one of (1) to (8), wherein the copolymer (B) having an epoxy group is rubber.
(10) The rubber having an epoxy group is a (meth) acrylic acid ester-ethylene- (unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer, Resin composition.
(11) The (meth) acrylic acid ester is methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl. The resin composition as described in (10), comprising at least one selected from methacrylates.
(12) A block in which the copolymer (B) having a functional group reactive with polylactic acid contains a structure of at least one vinyl aromatic compound, and a block containing a structure of at least one conjugated diene compound The functional group in the copolymer (B) component showing a microphase-separated structure is on the block side in direct contact with the component (A) which is polylactic acid. The resin composition according to any one of (1) to (3).
(13) The resin composition according to (12), wherein the copolymer (B) having a functional group reactive with polylactic acid is a styrene elastomer.
(14) The resin composition according to any one of (12) and (13), wherein the copolymer (B) is a triblock copolymer containing an epoxy group.
(15) From a resin composition obtained by melt-kneading 30 to 99% by weight (A) of polylactic acid and 70 to 1% by weight (B) of a copolymer having a functional group reactive with the polylactic acid The resin composition has a structure in which a reactive copolymer (B) is discontinuously dispersed as a dispersed phase having an average particle size in the range of 10 microns to 10 nanometers in a continuous phase composed of polylactic acid (A). And a broad halo diffraction pattern derived from an amorphous substance is dominant in the X-ray diffraction profile.
(16) A molded product obtained by molding the resin composition according to any one of (1) to (14).
(17) The molded product according to (16), wherein the molding process is injection molding.
(18) The molded product according to (16), wherein the molding process is press molding.
(19) The molded product according to (16), wherein the molding process is extrusion molding.
(20) The molded product according to (16), wherein the molding process is film molding.
(21) The molded product according to (16), wherein the molded product has a film shape, a sheet shape, or a plate shape.
(22) The molded body according to (16), wherein the shape obtained by processing the molded body is a net, fiber, nonwoven fabric, woven fabric, or filament.
(23) The molded body according to (16), wherein the molded body has a rod-like shape or an irregular shape.
(24) The molded product according to (16), wherein the molded product has a shape of a tube, a tube, a bottle, or a column.
(25) The molded body is a container, a part for household electrical appliances, a part for electric transmission, a housing material, a toy, a daily necessities, a material for agricultural / fishing industry, a mobile device part, a packaging material, a medical part, or an automobile part (16 ) The molded product described.

The resin composition obtained by the present invention is prepared by melt kneading 30 to 99% by weight of polylactic acid and 70 to 1% by weight (B) of a copolymer having a functional group reactive with the polylactic acid, In the continuous phase consisting of A), the reactive copolymer (B) has a discontinuously dispersed structure as a dispersed phase with an average particle size ranging from 10 microns to 10 nanometers, and in the X-ray diffraction profile The halo diffraction pattern derived from an amorphous substance is dominant, and this resin composition is a material with improved ductility, toughness, flexibility and impact resistance. When these properties are compared with the case of consisting only of polylactic acid, the impact strength is remarkably improved (about 2 to 20 times) while maintaining the thermal stability, particularly from brittleness to ductility (breaking elongation is 5% to 200%). The material is modified to one having the above.
It is a new environmentally safe material that takes into account the environment that replaces plastics that have been used in the past. For everyday items including toys and baby products, automotive parts, electrical and electronic parts, clothing, housing materials, and mobile equipment parts. A wide range of applications are expected.

  In order to produce the resin composition of the present invention, the blending ratio of polylactic acid (A) and copolymer (B) having a functional group reactive with the polylactic acid is set to A / B = 99.0. /1.0 to 30.0 / 70.0 (weight ratio), preferably 95/5 to 50/50 (weight ratio). Since a hydroxyl group and / or a carboxylic acid group is present at the chain end of polylactic acid (A), another function that causes a reaction such as a coupling reaction or an addition reaction with these functional groups at a high temperature at which melt kneading is performed. If the functional group is present in the copolymer (B), a new copolymer (AB) containing A and B is formed at the interface, and the copolymer (AB) is an emulsifier for an incompatible resin composition. It is possible to contribute to stabilizing dispersion, improving interfacial adhesion, and improving mechanical properties.

  In order to make polylactic acid into a continuous phase, the polylactic acid weight is not necessarily 50% or more of the total weight of the component polymer, and if the melt viscosity of the reactive copolymer at the kneading temperature is higher than the melt viscosity of polylactic acid, Even if the weight of polylactic acid is 50% or less, polylactic acid can be a continuous phase. When polylactic acid is no longer a continuous phase, the degree of biodegradation is significantly lost.

The resin composition obtained by the melt-kneading has a reactive phase in which the reactive copolymer (B) has a mean particle size ranging from 10 microns to 10 nanometers in a continuous phase composed of polylactic acid (A). It is characterized by comprising discontinuously dispersed states. Depending on the molecular weight and melt viscosity of the component polymer, the concentration and type of reactive groups contained in the reactive copolymer (B), and the conditions for molding, the reactive copolymer (B) has an average particle size of 10 to 10 microns. It varies over the nanometer range. When the particle size is 10 microns or more, the miscibility of the two component polymers is poor, and the characteristics as seen in the present invention are not exhibited. On the other hand, considering the dimension of the polymer chain, it is difficult to obtain a dispersed phase of 10 nanometers or less by melt kneading.
As an example, an electron micrograph (TEM) of (80/20) polylactic acid (A) / reactive copolymer (B) is shown in FIGS. 1a, 1b, and 1c. As is clear from these photographs, it is understood that the dispersion state changes in a wide range when the molecular weight and molding conditions of polylactic acid (A) are changed and melt kneaded. Specifically, the particle sizes of the dispersed phases in FIGS. 1a, 1b, and 1c are about 1-2 microns, 0.5 microns, and 0.1 microns, respectively.

  In addition, in the melt-kneading stage, if too much kneading is performed, polylactic acid (A) not only causes chemical degradation due to hydrolysis, but also mechanically causes chain scission and mechanical properties deteriorate, so care should be taken. is there. The L / D value of the melt kneader is preferably 70 or less. As an example, Table II was repeatedly melted and kneaded, and the results of the test of impact resistance of the obtained samples were shown for the L / D values described at that time. Here, when the L / D is in the range of 30 to 60, the notched impact test sample piece shows a partial fracture that is not divided into two, and although it has a high impact strength, the L / D value is At 90, it became clear that the test piece broke into two, causing complete destruction, and the impact strength decreased.

The component polymer of the resin composition of the present invention contains almost no higher-order crystal structure. This can be confirmed by the fact that when X-ray diffraction measurement is performed, the scattered X-rays have dominant diffraction patterns called broad halos derived from amorphous substances. Polylactic acid (A) has three crystal structures, α-type, β-type, and γ-type. The α type is the most stable structure, the β type appears when highly stretched at high temperatures, and the γ type is found in epitaxial crystallization. In order to express the characteristics of the resin composition of the present invention, the composition under molding processing conditions in which the crystal peak of polylactic acid (regardless of crystal structure) does not appear with a stronger intensity than the background halo of the diffraction pattern. Need to get. For example, it is not necessary to use amorphous D, L-form (racemic) polylactic acid, or crystalline L-form polylactic acid or D-form polylactic acid with high optical purity. Even if not, it is possible to avoid gradual cooling, which causes crystallization when solidifying in the molding process, and to cool as quickly as possible.
For example, scattering from α-type (110) crystal plane and (203) plane appears in the vicinity of 2q = 16.5 ^o and 19 ^{o in} wide angle X-ray diffraction (WAXD) measurement, so confirm crystallization. Can do. It has been confirmed that as the crystal structure is formed, the mechanical properties change greatly, and in particular, the ductile properties rapidly decrease.
[Polylactic acid (weight average molecular weight ( _Mw ) = about 140 to 150,000)] in FIG. 2a, [Polylactic acid ( _Mw = about 200,000)] in FIG. 2b, and [Screw rotation speed of 200 rpm]. (80/20) Polylactic acid (M _w = about 14-150,000) / resin composition produced from reactive polyethylene copolymer], FIG. 2d [(80/20) poly produced at a screw rotation speed of 200 rpm Wide angle X-ray diffraction measurement (WAXD) profile of lactic acid (M _w = about 200,000) / resin composition produced from reactive polyethylene copolymer] was shown. These polylactic acids contained 98% or more of L-form, but were molded under conditions where crystallization did not occur as much as possible. As is clear from this result, the sharp crystal peak due to the component polymer does not appear clearly, the amorphous halo diffraction pattern is dominant, and the component polymer in the resin composition is almost an amorphous substance. I understand that.
As a result of calculating the crystallinity of the sample by differential scanning calorimetry (DSC) and calculating the heat of fusion (ΔH _f ) of 93 (J / g), the crystallinity of these samples is the PLA in FIGS. 2a and 2b. It was about 5% by itself, and about 10% with the PLA alloy of FIGS. 2c and 2d.

The polylactic acid (A) is as follows.
Lactic acid has L-lactic acid and D-lactic acid as optical isomers, and polylactic acid obtained by polymerizing them contains about 10% or less of D-lactic acid unit and about 90% or more of L-lactic acid unit, Or a polylactic acid having an L-lactic acid unit of about 10% or less and a D-lactic acid unit of about 90% or more, an optical purity of about 80% or more, and a D-lactic acid unit of 10% to 90% It is known that there are polylactic acid having an L-lactic acid unit of 90% to 10% and amorphous polylactic acid having an optical purity of about 80% or less. The polylactic acid used in the present invention may be a D-form, an L-form, or a mixture D or L-form thereof, but higher-order crystals are used when crystalline polylactic acid (D-form, L-form) is used. In order not to form the structure, it is necessary to be careful not to perform slow cooling from the molten state. In that respect, when using amorphous polylactic acid (D, L-form), such a caution is not necessary, so that it is a more preferable raw material for the present invention.
The weight average molecular weight of g polylactic acid is in the range of 5,000 to 1,000,000. If it is less than this range or exceeds this range, a sufficient effect cannot be expected when a polymer composition is obtained. In particular, when the molecular weight is too high, the concentration of polylactic acid end groups causing the reaction is too low, and the melt viscosity becomes too high to cause an interfacial reaction with the reactive copolymer. The range is preferably 20,000 to 700,000, more preferably 20,000 to 500,000.

  In order to improve the moldability of polylactic acid, for example, a small amount of polyol, glycol, or acid may be added to partially block the end group of polylactic acid to adjust the molecular weight. As an example, it can be stably molded by copolymerizing polyethylene glycol with polylactic acid in an amount of 0.5 to 10% by weight.

  The functional group of the copolymer (B) having a functional group reactive with the polylactic acid may be any one that reacts with the polylactic acid (A) end group (hydroxyl group, carboxylic acid group). Amino group, isocyanate group, oxazoline group, carbodiimide group, ortho-ester group, maleic anhydride, phthalic anhydride and the like. An epoxy group is preferable.

  Epoxy groups and the like may be present as part of other functional groups, and examples thereof include glycidyl groups.

As such a monomer having a functional group, a monomer containing a glycidyl group is particularly preferably used. As an example of a monomer containing a glycidyl group, an unsaturated carboxylic acid glycidyl ester or an unsaturated glycidyl ether represented by the following general formula is preferably used.

  Examples of the unsaturated carboxylic acid glycidyl ester include glycidyl acrylate, glycidyl methacrylate, itaconic acid diglycidyl ester, butenetricarboxylic acid triglycidyl ester, and p-styrene carboxylic acid glycidyl ester.

Examples of the unsaturated glycidyl ether include vinyl glycidyl ether, allyl glycidyl ether, 2-methylallyl glycidyl ether, methacryl glycidyl ether, and styrene-p-glycidyl ether.
Specifically, it is preferable to contain 0.1-30 mass% of unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether units, and it is more preferable to contain 0.1-20 mass%.

  The method for introducing such a functional group into the copolymer (B) is not particularly limited, and can be performed by a known method. For example, it can be introduced by copolymerizing the monomer having the functional group at the stage of synthesis of the copolymer, or the monomer having the functional group can be grafted onto the copolymer. It is also possible to do. It is also possible to introduce an epoxy group by an unsaturated bond chemical reaction.

  The method for introducing the above functional group into the rubber in the composition containing the rubber in the copolymer (B) is not particularly limited, and can be performed by a known method. For example, at the rubber synthesis stage, the monomer having the functional group can be introduced by copolymerization, or the monomer having the functional group can be graft-copolymerized on the rubber.

The copolymer (B) having a functional group reactive with polylactic acid may be a thermoplastic resin, a rubber, or a mixture of rubber and a thermoplastic resin. Good.
Examples of the thermoplastic resin having an epoxy group include a resin comprising (a) an ethylene unit, (b) an unsaturated carboxylic acid glycidyl ester unit and / or an unsaturated glycidyl ether unit, and (c) an ethylenically unsaturated ester compound copolymer. be able to.
Specific examples of rubber are as follows.
(1) (acrylic) rubber having an epoxy group, (2) vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer, and the like.

  For example, as a thermoplastic resin having an epoxy group, (a) ethylene unit is 60 to 99% by weight, (b) unsaturated carboxylic acid glycidyl ester unit and / or unsaturated glycidyl ether unit is 0.1 to 20% by weight. (C) An epoxy group-containing ethylene copolymer comprising 0 to 40% by weight of an ethylenically unsaturated ester compound unit.

  The definition and specific examples of the (b) unsaturated carboxylic acid glycidyl ester unit and / or unsaturated glycidyl ether unit are the same as described above.

  Examples of the ethylenically unsaturated ester compound (c) include vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Examples include esters and α, β-unsaturated carboxylic acid alkyl esters. In particular, vinyl acetate, methyl acrylate, and ethyl acrylate are preferable.

  Examples of the epoxy group-containing ethylene copolymer include a copolymer composed of ethylene units and glycidyl methacrylate units, a copolymer composed of ethylene units, glycidyl methacrylate units and methyl acrylate units, ethylene units, glycidyl methacrylate units and acetic acid. Mention may be made of copolymers comprising vinyl units.

The epoxy group-containing ethylene copolymer is preferably in the range stiffness modulus of 10~1300kg / cm ^2, further preferably from 20~1100kg / cm ^2. If the flexural modulus is outside this range, the mechanical properties of the composition may be insufficient.

  The copolymer (B) may be a copolymer having a heat of fusion of less than 3 J / g in order to improve the thermal stability and flexibility of the molded article of the present invention. preferable.

  The epoxy group-containing ethylene copolymer is usually an unsaturated epoxy compound and ethylene in the presence of a radical generator at 500 to 4000 atm and 100 to 300 ° C. in the presence or absence of a suitable solvent or chain transfer agent. It can also be produced by a method in which a high-pressure radical generator to be copolymerized is mixed and melt graft copolymerized in an extruder.

  The melt index of the epoxy group-containing ethylene copolymer (hereinafter sometimes referred to as MFR. JIS K6760, 190 ° C., 2.16 kg load) is preferably 0.5 to 100 g / 10 min, more preferably 2 ~ 50 g / 10 min. When the melt index exceeds 100 g / 10 min, it is not preferable in terms of mechanical properties when it is made into a composition, and when it is less than 0.5 g / 10 min, the compatibility with the component (A) is inferior.

  The copolymer (B) preferably has a Mooney viscosity of 3 to 70, more preferably 3 to 30, and particularly preferably 4 to 25. The Mooney viscosity here is a value measured using a 100 ° C. large rotor according to JIS-K6300.

The (acrylic) rubber having an epoxy group in the specific example (1) of the rubber is as follows.
A (meth) acrylic acid ester (or methacrylic acid ester) -ethylene- (unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer rubber is preferred.

  Examples of the (meth) acrylic acid ester include methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. Can be mentioned.

  In the case of a system that does not show a microphase-separated structure such as a random copolymer, it does not matter so much where a functional group is introduced in the polymer chain. However, it is more preferable that it is introduced into the side chain than in the main chain, and the reaction proceeds more efficiently.

The vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer having an epoxy group in specific example (2) of the rubber is as follows.
Examples of the vinyl aromatic hydrocarbon compound in the vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer rubber include styrene, vinyl toluene, divinyl benzene, α-methyl styrene, p-methyl styrene, vinyl naphthalene, and the like. be able to. Of these, styrene is preferred. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, 3-butyl-1,3-octadiene, and butadiene or isoprene is preferable.
Such a vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer or a hydrogenated product thereof can be produced by a known method. For example, in Japanese Patent Publication No. 40-23798 and Japanese Patent Application Laid-Open No. 59-133203. Are listed.

  A vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer rubber that forms a copolymer with a monomer having a functional group reactive with polylactic acid is a vinyl aromatic carbonization obtained by the above-described method. The hydrogen compound-conjugated diene compound block copolymer can be obtained by introducing a monomer having reactivity with polylactic acid such as an epoxy group. The method for introducing such a monomer into the vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer is not particularly limited, but is preferably introduced by graft copolymerization or the like.

  The copolymer (B) having a functional group reactive with polylactic acid may be a triblock copolymer.

  The functional group in the block copolymer (B) component showing a microphase-separated structure is added on the block side in direct contact with the polylactic acid (A) component (for example, one block of the component (B) is spherical or rod-shaped) If the microphase separation structure is taken, it means the other block side having a continuous structure surrounding the microphase separation structure, and in the case of taking a microphase separation structure such as a layer structure or a co-continuous structure, either block may be used. It is preferable.

  Examples of the triblock copolymer as the component (B) of the present invention also include a styrene-ethylene-butylene-styrene block copolymer having a functional group reactive with polylactic acid.

  The styrene content of the styrene-butadiene block copolymer is preferably 5 to 80% by mass, and more preferably 2 to 50% by mass. The same applies to other styrenic block copolymers (for example, SEBS, SEB, SBS, SB, SI, SIS, SEP, SEPS, etc.).

On the other hand, if the block copolymer has a heterogeneous structure such as microphase separation, such as styrenic thermoplastic elastomers (eg, SEBS, SEB, SBS, SB, SI, SIS, SEP, SEPS, etc.) The position where the group is introduced is important. In the case of a structure having a sea-island structure (spherical or rod-like dispersed phase in three dimensions), when a group that reacts with polylactic acid is introduced into the dispersed phase, the continuous phase surrounding the group causes contact with polylactic acid. The reaction does not proceed efficiently because it is hindered.
In particular, when a reactive group (for example, maleic anhydride or the like) that is not highly reactive with polylactic acid is introduced, the influence becomes greater.

  For example, when a hard elastomer having a high styrene content is used in a styrene-butadiene block copolymer, styrene is a continuous phase and butadiene is a dispersed phase, and therefore a group having reactivity with polylactic acid exists in the styrene block. Is preferable.

For example, in a styrene-butadiene block copolymer, when the butadiene content is high, butadiene is a continuous phase, and styrene is a dispersed phase, if the reactive group is present in the continuous phase of butadiene, the reaction with the polylactic acid end group is not caused. Since it becomes easy, the efficiency of reaction rises and it is more preferable. This effect is particularly great when the copolymer has reactive groups that are not very reactive with polylactic acid such as maleic anhydride.
Thus, Table I shows an example in which reactive groups are introduced in different blocks. The modified styrene block (copolymer-2) with maleic anhydride (MAH) attached to the styrene block, which is the dispersed phase of styrene-ethylene-butadiene-styrene triblock copolymer (SEBS), and the ethylene-butadiene block in the continuous phase The results of alloying with polylactic acid using modified SEBS (copolymer-3) are shown. (Polylactic acid content = 80% by weight, SEBS content = 20% by weight) As a comparison, the results of non-reactive SEBS (copolymer-1) having no functional groups are also listed. As is clear from this table, the modified SEBS (copolymer-3) in which MAH groups are introduced in the continuous phase is alloyed with polylactic acid, and the modified phase in which MAH groups are introduced in the dispersed phase It can be seen that the reaction with polylactic acid is easier than SEBS (copolymer-2), and the effect of alloying is remarkably enhanced.

  As described above, when styrene becomes a dispersed phase in a styrene-based elastomer composed of triblocks, the functional group is added to the continuous phase even if the synthesis becomes two steps by taking the trouble of introducing the functional group. It is preferable to introduce N because the reaction efficiency with polylactic acid increases. However, in reality, if a functional group is introduced at the synthesis stop stage, the synthesis is completed in one stage. Therefore, there are many examples in which the functional group is introduced into the terminal styrene block from the viewpoint of cost and labor.

  The rubber as the copolymer (B) used in the present invention can be vulcanized as necessary and used as a vulcanized rubber.

  In the case of vulcanization of acrylic acid ester (or methacrylic acid ester) -ethylene- (unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer rubber, polyfunctional organic acid, polyfunctional amine compound, imidazole This is achieved by using a compound or the like, but is not limited thereto.

  In the method for producing the polymer composition of the present invention, the respective components are kneaded (melt kneaded) in the molten state of the pellet mixture. In the melt-kneading, generally used kneading apparatuses such as a single-screw or twin-screw extruder, various kneaders, and a mixer can be used. Among these, a twin screw extruder is preferable. The melt kneading temperature is in the range of about 180 to 250 ° C. In order to prevent hydrolysis during melt-kneading, the pellets must be sufficiently dried in advance. If the drying is not performed sufficiently, a composition showing good physical properties cannot be obtained.

When melt kneading too much, kneading too much should not only cause polylactic acid (A) to undergo chemical degradation due to hydrolysis, but also mechanically cause chain breakage, resulting in deterioration of mechanical properties. . Table as an example
The results obtained by repeating melt melting and kneading in II and summarizing the test results of the impact resistance of the obtained samples with respect to the stated L / D values are shown. Here, when the L / D is in the range of 30 to 60, the notched impact test sample piece shows a partial fracture that is not divided into two, and although it has a high impact strength, the L / D value is At 90, it was found that the test piece was broken into two, causing complete destruction, and the impact strength decreased. That is, it is not necessary to knead a lot, but in the case of polylactic acid, the influence of deterioration that occurs during kneading should be taken into consideration, and the L / D value is preferably 70 or less.

  By melt-kneading, it is possible to obtain a polymer composition in which a copolymer (B) having a functional group reactive with polylactic acid is finely dispersed in a matrix of polylactic acid (A).

At the time of melt kneading, each component may be supplied to the kneading apparatus after the components are uniformly mixed in advance by a device such as a tumbler or a Henschel mixer, or a method in which each component is separately metered into the kneading apparatus. Can also be used.
The temperature in the tumbler or Henschel mixer is 180 ° C or higher. Usually, the temperature may be about 210 ° C., and a temperature that is higher than 280 ° C. should be avoided.

The resin composition comprising the polylactic acid (A) and the copolymer (B) having a functional group reactive with the polylactic acid includes a lubricant and, if necessary, a static if used as a film. You may contain additives, such as a metal compound as an electro pinning property imparting agent, or a flame retardant (organic phosphorus type, boric acid type, aluminum hydroxide, etc.), an antifoamer.
In addition, organic fillers, antioxidants, heat stabilizers (phenolic, aromatic amine, organic sulfur, organic phosphorus, etc.), light stabilizers, inorganic or organic colorants, rust inhibitors, crosslinkers, Various additives such as a foaming agent, a fluorescent agent, a surface smoothing agent, a surface gloss improving agent, and a mold release improving agent such as a fluororesin may be contained.

  As for the method of adding these additives, if they have heat stability, they may be added during resin kneading, and if they do not have heat stability, they are separately applied, contained, or surface treated after kneading. The method is not particularly limited, and an optimum method may be used according to the application. When these additives are kneaded in a small amount or when the surface is mainly treated, the mechanical properties of the resin composition of the present invention are mainly determined by bulk properties, so that the ductility, toughness, flexibility, The properties such as impact properties are retained and can be used in fields where these are utilized.

Each molded body can be obtained by molding the polymer composition into a desired shape by various known molding methods. Specifically, the following molding methods can be mentioned. Extrusion molding, injection molding, rotational molding, blow molding, blow molding, transfer molding, press molding, solution casting, and the like.
In accordance with the molding method, the molded bodies obtained by these molding methods are sequentially formed into an extruded molded body, an injection molded body, a rotational molded body, a blow molded body, a blow molded body, a transfer molded body, a press molded body, and a solution. It is called a cast method molding.
In the present invention, an amorphous polylactic acid resin composition is targeted. In order to prevent crystallization at the molding stage, it is necessary to set the mold temperature as low as possible and obtain a molded body by rapid cooling. If the control at this stage is not performed, the crystallinity of the composition is greatly changed, and different physical properties are obtained.

  When an impact test is performed on a sample obtained by injection molding according to JIS K7111 (ISO 179), as shown in Tables III and IV, the Charpy impact value with a notch is higher than that of polylactic acid alone. A thing with an impact value of about 2 to 20 times is obtained. A wide range of uses such as automobile parts, household appliance parts and housing materials, baby products and toys can be considered as safe and non-breakable materials using this characteristic.

  To obtain home appliance parts, electric parts, automobile parts (bumpers, instruments, etc.) by injection molding, the molten resin composition is transferred from the extruder into the mold using an injection molding machine. A method of injecting at high pressure can be used.

  When the sample obtained by injection molding was tested according to JIS K7113, as shown in Tables III and IV, the resin composition of the present invention has a breaking elongation of about 40 times or more compared to polylactic acid alone. Is obtained. Thereby, it turns out that the originally weak polylactic acid was modified into a ductile material.

  When the sample obtained by injection molding was tested according to JIS K 7191-1 method (ISO75-1), as shown in Table III and Table IV, the heat deformation temperature (T ° C.) The heat distortion temperature of the resin composition is in the range of (T−5 ° C.) to (T + 5 ° C.). Specifically, the difference in heat distortion temperature (HDT) is about 2 ° C., and the heat stability of the polylactic acid-containing resin composition is almost the same as that of polylactic acid.

To obtain the films by molding the resin composition of the present invention. For example, the method of supplying the said resin composition to the extruder provided with die | dye (die) can be used.
As a die used for manufacturing films, a T die and a cylindrical slit die are preferably used. Moreover, the casting method, the heat press method, etc. are applicable to manufacture of films.

When the said molded object is films, the thickness is not specifically limited, However, The range of 1-1000 micrometers is preferable practically, The range of 1-500 micrometers is more preferable. The film surface can be subjected to surface treatment as necessary. Examples of such surface treatment methods include irradiation with α rays, β rays, γ rays or electron beams, corona discharge treatment, plasma treatment, flame treatment, infrared treatment, sputtering treatment, solvent treatment, polishing treatment and the like. Furthermore, there are cases where application of a resin such as polyamide or polyolefin, vapor deposition of a metal such as laminate or aluminum oxide, or a coating such as silicon oxide or titanium oxide may be performed.
These treatments may be performed during the molding process or may be performed on the film or sheet after the molding process. However, such a process may be performed in the molding process, particularly before the winder. preferable.

  In order to further improve the film production and process passability, it is desirable to add a necessary amount of an inorganic lubricant such as silica, alumina, kaolin and the like to form a film to impart slip properties to the film surface. Furthermore, in order to improve the printing processability of the film, for example, an antistatic agent or the like can be contained.

  The film of the present invention has improved toughness, flexibility, impact resistance, and significantly improved impact value while maintaining thermal stability, and from brittleness to ductility (40% elongation at break) than the film of polylactic acid alone. In addition, it has excellent flexibility, oil resistance, adhesiveness, and heat sealability. Therefore, food packaging films and tapes that make use of these properties, garbage packaging bags, laminate films, electricity -It can also be suitably used for applications such as wrapping of electronic parts, recording media shrink films, agricultural and fishery films.

  Moreover, in order to obtain a filament by molding, a method of winding the resin composition at a high speed after melt extrusion into a strand die by an extruder can be used.

  In order to obtain a hollow molded body such as a container or a bottle by molding the resin composition, for example, a blow molding machine is used to blow a fluid pressure such as air or water into the resin composition, thereby A method (blow molding) for close contact with the mold can be used. Injection molding can also be applied.

  Moreover, in order to shape | mold said resin composition and to obtain a pipe | tube and a tube, the method of melt-extrusion from an extruder to a tube die can be used using a tube molding machine.

  As described above, the shape of the molded body may be a film shape, a sheet shape or a plate shape, a net shape, a fiber shape, a nonwoven fabric shape, a woven fabric shape, or a filament shape. , Containers and the like. The shapes of these molded products are film (film, sheet, etc.), plate, columnar, box, filament, nonwoven fabric, woven fabric, tubular, tube, and other irregular shapes.

  As mentioned above, safe and excellent mechanical properties, environmentally friendly materials such as toys, baby goods, household goods including containers, home appliance parts, office equipment, automobile parts, medical equipment, electrical / electronic parts, It is also suitable for AV equipment, nets in the fisheries field, filters, clothing applications, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited only to these. Moreover, the test of this invention is based on the following method.

(1) Tensile test
The test was carried out according to JIS K7113 using an injection molded (about 4 mm thickness) ISO 3167 type A multipurpose test piece. The testing machine used UTM-III-10T Orientec Tensilon. The measurement was repeated 3-5 times on the same sample.
The tensile modulus and elongation at break were determined from the above tensile test.

(2) Flexural modulus ISO 3167 type A multi-purpose test pieces were prepared by injection molding, and the three-point bending property test method was performed at a test speed of 2 mm / min according to JIS K7171 (ISO 178). The test machine used the same model as (1).

(3) Measurement of heat distortion temperature (HDT) A multi-purpose test piece of ISO 3167 type A was prepared by injection molding, a sample piece (thickness of about 4 mm) was cut out according to JIS K7191 (ISO 75-2), and the deflection temperature under load The following tests were conducted. The test conditions were a bending stress applied to the test piece of 1.80 MPa and a flat-wise method for placing the test piece. The testing machine used was a Toyo Seiki thermal deformation (HDT) testing machine (3M-2).

(4) Tensile impact test After a 0.5 mm thick quenched film was prepared by hot pressing, the test piece was punched into a dumbbell type (1/2 size of JIS K7163 (ISO527-3) type 5 test piece), and JIS A tensile impact test (manufactured by Toyo Seiki Co., Ltd.) was conducted according to K7160 (ISO 8256). The results in Table I used this method.

(5) Charpy impact test with notch ISO 3167 Type A multi-purpose test piece (about 4 mm thick) is made by injection molding, cut out a sample piece according to JIS K7111 (ISO 179), and has a type A notch, edgewise method A Charpy impact test (manufactured by Toyo Seiki) was conducted. Table II, Table III, and Table IV determined the impact strength by this method.

(6) Wide-angle X-ray diffraction (WAXD) measurement Using a Rigaku Ultrax 8000 by the transmission method, measurement was performed under the conditions of a CuKα radiation source and 40 kV 70 mA.

The raw materials used in the examples and comparative examples are as follows.
(A) component: Polylactic acid (PLA)
(I) H-100 manufactured by Mitsui Chemicals (hereinafter, this may be abbreviated as PLA-1) [MFR at 190 ° C. is 8 g / 10 min, weight average molecular weight M _w = about 140 to 150,000, D-form Content = 1-2%, glass transition point 62.5 ° C, melting point 164 ° C]
(B) H-400 manufactured by Mitsui Chemicals (hereinafter sometimes abbreviated as PLA-2) [MFR at 190 ° C. is 3 g / 10 min, weight average molecular weight M _w = about 200,000, D-form content = 1-2%, glass transition point 63 ° C, melting point 166 ° C]
Component (B): copolymer reactive with polylactic acid (a) non-reactive styrene-ethylene-butadiene-styrene block copolymer (this may hereinafter be abbreviated as copolymer-1) [M _n = 50,000, styrene content = 31.5 wt%, hydrogenation rate = 93%, functional group concentration = 0 wt%]
(B) Maleic anhydride-modified styrene-ethylene-butadiene-styrene block copolymer (hereinafter sometimes abbreviated as Copolymer-2) [M _n = 40,000, styrene content = 30% by weight Hydrogenation rate = 81%, maleic anhydride concentration = 0.7 to 0.8% by weight, position where functional group is introduced = one-end styrene block]
(C) Maleic anhydride-modified styrene-ethylene-butadiene-styrene block copolymer (hereinafter sometimes abbreviated as copolymer-3) [M _n = 50,000, styrene content = 30% by weight Hydrogenation rate = 93%, maleic anhydride concentration = 0.6% by weight, position where functional group is introduced = ethylene-butadiene block]
(D) Epoxy-modified copolymer (hereinafter sometimes abbreviated as Copolymer-4) [Sumitomo Chemical Co., Ltd., Bond First 7L [ethylene / methyl acrylate / glycidyl methacrylate random copolymer] Polymer = 67/30/3 weight ratio, MFR (190 ° C., 2.16 kg) = 9 g / 10 min]
(E) Epoxy-modified copolymer (hereinafter, this may be abbreviated as Copolymer-5) [Epofriend AT501 (styrene-butadiene-styrene block copolymer, styrene, manufactured by Daicel Chemical Industries, Ltd.) / Butadiene = 40/60 weight ratio, MFR (190 ° C., 2.16 kg) = 7 g / 10 min), hydrogenation rate is 0%. Functional group introduction position is butadiene block]
(F) Epoxy-modified copolymer (hereinafter, this may be abbreviated as Copolymer-6) [Epofriend HT302 (styrene-butadiene-styrene block copolymer, styrene, manufactured by Daicel Chemical Industries, Ltd.) / Butadiene = 20/80 Weight ratio, MFR (190 ° C., 2.16 kg) = 2 g / 10 min) Hydrogenation rate is about 50%. Functional group introduction position is butadiene block]

Next, each experimental method will be described.
In Table I, the PLA-1 (A) was vacuum-dried at 80 ° C. for 8 hours, and the three types of component (B) of the copolymer-1, copolymer-2 and copolymer-3 were 60 ° C. For 4 hours. Then, 80 parts by weight of raw material PLA-1 and 20 parts by weight of copolymer are mixed and mixed in a batch type small twin screw extruder (HAAKE Minilab Rheomex) at 210 ° C., screw rotation speed = 100 rpm, reaction time = 7. The mixture was melt kneaded in minutes to obtain a composition. The obtained sample was vacuum-dried at 60 ° C., and then a quenched film having a thickness of 0.5 mm was prepared by hot pressing, and the dumbbell type (1/2 size of JISK7163 (ISO527-3) type 5 test piece) was used. The specimen was punched out and a tensile impact test (manufactured by Toyo Seiki) was performed.

  In the experiment of Table II, the PLA-1 (A) was vacuum-dried at 80 ° C. for 8 hours, the copolymer-6 (B) was vacuum-dried at 60 ° C. for 4 hours, and then the following raw material PLA-1 80 2 parts by weight, copolymer-6 20 parts by weight of pellets are mixed to produce a twin screw extruder [Technobel's twin screw extruder KZW15-30MG (screw outer diameter 15 mm, segment type screw, L / D = 30) ] Melt-kneaded. At this time, in order to see the effect of kneading, the obtained mixture was repeated and put into a twin screw extruder to obtain a highly kneaded composition. The pellets of the composition thus obtained were vacuum-dried at 60 ° C, and then ISO dumbbell-type sample pieces were prepared on an injection molding machine (FANAC ROBOSHOT α-100A type) set at a mold temperature of 35 ° C. A Charpy impact test with a notch was conducted.

  Next, the experimental methods in Tables III and IV are as follows.

  The PLA-1 (A) was vacuum-dried at 80 ° C. for 8 hours, and the copolymer-4 (B) was vacuum-dried at 60 ° C. for 4 hours. Then, the following raw material PLA-1 95 parts by weight, copolymer -4 5 parts by weight of the pellets was mixed and melt-kneaded with a twin-screw extruder [Technobel's twin-screw extruder KZW15-30MG (screw outer diameter 15 mm, segment type screw, L / D = 30)]. A twin-screw extruder with a vacuum vent is heated to 170-215 ° C., the above pellets are mixed and added, kneaded at a screw speed of 30 rpm, and the molten strand discharged from the extruder is cooled in water. A pellet was obtained with a pelletizer. The pellets were vacuum-dried at 60 ° C., and ISO dumbbell-type sample pieces were prepared with an injection molding machine (FANAC ROBOSHOT α-100A type) set at a mold temperature of 35 ° C. The heat distortion temperature (HDT) was measured, and a notched Charpy impact test, a tensile test, and a bending test were performed. The results are summarized in Table III.

  The procedure was the same as in Example 1 except that 80 parts by weight of PLA-1 and 20 parts by weight of copolymer-4 were used, and the results of physical property tests are summarized in Table III.

  Using the pellets of PLA-1 80 parts by weight and copolymer-4 20 parts by weight, the same procedure as in Example 1 was carried out except that the melt rotation kneading was performed at a screw rotation speed of 200 rpm. It is summarized in Table III.

  Using pellets of PLA-2 80 parts by weight and copolymer-4 20 parts by weight, the same procedure as in Example 1 was performed except that the melt rotation was carried out at a screw rotation speed of 200 rpm. It is summarized in Table III.

  PLA-1 was processed in the same manner as in Example 1 except that 80 parts by weight of the pellets and 20 parts by weight of copolymer-5 were melt kneaded at a screw rotation speed of 200 rpm. It is summarized in Table III.

  PLA-1 was treated in the same manner as in Example 1 except that pellets consisting of 80 parts by weight and copolymer-6 20 parts by weight were melt kneaded at a screw rotation speed of 200 rpm. It is summarized in Table III.

Comparative Example 1

  The same operation as in Example 1 was conducted except that the raw material pellets consisted of 100 parts by weight of PLA-1 and the results of the physical property tests are summarized in Table IV.

Comparative Example 2

The same operation as in Example 1 was performed except that the raw material pellets consisted of 100 parts by weight of PLA-2, and the results of physical property tests are summarized in Table IV.

Table I Influence of position of functional group of component (B) having micro phase separation structure

Table I shows the relationship between the position of the functional group in the SEBS copolymer and the impact value of the alloy for an alloy composed of a modified SEBS elastomer having a microphase separation structure and polylactic acid. Here, copolymer-1 is a non-reactive SEBS containing no functional group, copolymer-2 is a modified SEBS in which a maleic anhydride group (MAH) is introduced into a terminal styrene block, and a copolymer -3 is a modified SEBS in which a maleic anhydride group (MAH) is introduced into the EB block at the center of the polymer chain. Here, in these three kinds of elastomers, a styrene block having a low content forms a dispersed phase, and an EB block having a high content forms a continuous phase.
As is clear from Table I, the copolymer-3 in which the reactive group was introduced toward the continuous phase was markedly different from the copolymer-2 in which the functional group was introduced into the dispersed phase. Interfacial reaction is effective. Furthermore, the tensile impact value of copolymer-2 was only about the same as that of copolymer-1 which is non-reactive SEBS.

Table II Influence of melt kneading on mechanical properties of polylactic acid alloy ((80/20) PLA-1 / copolymer-6)
* A more kneaded sample piece was prepared by repeatedly using a twin screw extruder. The L / D value here is the L / D value described.

There are many descriptions of sufficient melt-kneading in the patents so far, but Table II shows the results of studying whether this is the case with the system of the present invention. Here, the L / D value in the description of melt kneading was changed, and the impact values of the obtained compositions were compared. As a result, it was clearly shown that even if the L / D value is up to 60, even if the high impact strength is maintained, too much kneading causes a decrease in physical properties. In other words, in the case of polylactic acid, not only chemical degradation due to hydrolysis occurs, but also mechanical chain force may cause chain breakage of the polymer, so better physical properties can be obtained by increasing the kneading. It does n’t mean you can.

Table III Examples

Table IV Comparative example

  As is clear from the comparison between Examples 2, 3, 5, and 6 and Comparative Example 1, and the comparison between Example 4 and Comparative Example 2, the polylactic acid-containing resin composition of the present invention has a much higher tensile strength than the raw polylactic acid. The elongation at break (about 8 to 40 times or more) was exhibited, and ductility was added. Further, the flexural modulus was reduced to about 40 to 67%, and the flexibility was improved.

  As is clear from the comparison between Examples 1, 2, 3, 5, 6 and Comparative Example 1 (about 2 to 20 times), and the comparison between Example 4 and Comparative Example 2 (about 2 times), the product of the present invention is It showed much higher impact strength than polylactic acid. The 20% containing system was superior in impact resistance to the 5% copolymer containing system. Also, there is a difference depending on the component polymer used even if it is molded under the same conditions, and the impact strength is particularly dramatic in the system using copolymer-6 or the system using PLA with a low molecular weight (PLA-1). Improved.

  As can be seen from the comparison between Examples 2, 3, 5, and 6 and Comparative Example 1 and between Example 4 and Comparative Example 2, the heat distortion temperature of the polylactic acid-containing resin composition of the present invention and the polylactic acid alone is shown. The difference in (HDT) was 2 ° C or less, and it became clear that the thermal stability was almost the same as that of polylactic acid.

  Next, in FIGS. 1 (a), (b) and (c), the poly (lactic acid) produced from (80/20) polylactic acid (A) / reactive copolymer (B) shown in Examples 2 to 4, respectively. The electron micrograph of the lactic acid containing resin composition was shown. In FIG. 1 (a), a copolymer dispersed phase having a particle size of about 1 to 2 microns, FIG. 1 (b) about 0.5 microns, and FIG. 1 (c) about 0.1 microns is a polylactic acid continuous phase. It exists in the sea island structure. It can also be seen that the dispersion state varies widely depending on the molding conditions and the molecular weight of polylactic acid.

The figure which shows the electron micrograph of the polylactic acid containing resin composition of this invention.
Example 2: Melting and kneading with a polylactic acid-1 (A) / copolymer-4 (B) weight ratio of 80/20 and a screw rotation speed of 30 rpm. Example 3: Melt kneading with a polylactic acid-1 (A) / copolymer-4 (B) weight ratio of 80/20 and a screw rotation speed of 200 rpm. Example 4: Melting and kneading with a polylactic acid-2 (A) / copolymer-4 (B) weight ratio of 80/20 and a screw rotation speed of 200 rpm. The spectrum of the wide angle X-ray diffraction (transmission method) of the polylactic acid containing resin composition of this invention. [(a) Comparative Example 1: Polylactic acid-1 (A), (b) Comparative Example 2: Polylactic acid-2 (A), (c) Example 3: Polylactic acid-1 (A) / copolymer (D) Example 4: Polylactic acid-2 (A) / copolymer-4 (B) weight ratio is 80/20. The weight ratio of 4 (B) is 80/20 and the screw rotation speed is 200 rpm. 20. Melting and kneading at a screw rotation speed of 200 rpm. ]

Claims (25)

  It comprises a resin composition obtained by melt-kneading 30 to 99% by weight (A) of polylactic acid and 70 to 1% by weight (B) of a copolymer having a functional group reactive with the polylactic acid, The resin composition has a structure in which a reactive copolymer (B) is discontinuously dispersed as a dispersed phase having an average particle size ranging from 10 microns to 10 nanometers in a continuous phase composed of polylactic acid (A). A broad halo diffraction pattern derived from an amorphous substance is dominant in the X-ray diffraction profile.   The resin composition according to claim 1, wherein the polylactic acid (A) has a weight average molecular weight of 5,000 to 1,000,000.   3. The resin composition according to claim 1, wherein the copolymer (B) having a functional group reactive with polylactic acid is a copolymer having an epoxy group.   The copolymer (B) having an epoxy group contains 0.1 to 30% by weight of an unsaturated carboxylic acid glycidyl ester unit and / or an unsaturated glycidyl ether unit. The resin composition as described.   The resin composition according to any one of claims 1 to 4, wherein the copolymer (B) having an epoxy group contains a structure of an olefinic compound.   The copolymer (B) having an epoxy group is (a) 60 to 99 wt% of ethylene units, (b) 0.1 to 20 wt% of unsaturated carboxylic acid glycidyl ester units and / or unsaturated glycidyl ether units, The resin composition according to any one of claims 1 to 5, which is an epoxy group-containing ethylene copolymer comprising (c) 0 to 40% by weight of an ethylenically unsaturated ester compound.   The resin composition according to any one of claims 1 to 6, wherein the copolymer (B) having an epoxy group has a heat of fusion of less than 3 J / g.   The resin composition according to any one of claims 1 to 7, wherein the Mooney viscosity of the copolymer (B) having an epoxy group is in the range of 3 to 70.   The resin composition according to any one of claims 1 to 8, wherein the copolymer (B) having an epoxy group is rubber.   The resin composition according to claim 9, wherein the rubber having an epoxy group is a (meth) acrylic acid ester-ethylene- (unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer. .   The (meth) acrylic acid ester is selected from methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. The resin composition according to claim 10, comprising at least one selected from the group consisting of:   A block in which the copolymer (B) having a functional group reactive with polylactic acid has a block containing at least one vinyl aromatic compound structure and a block containing at least one conjugated diene compound structure The functional group in the copolymer (B) component, which is a copolymer and exhibits a microphase-separated structure, is added on the block side in direct contact with the polylactic acid (A) component. The resin composition in any one of 1-3.   13. The resin composition according to claim 12, wherein the copolymer (B) having a functional group reactive with polylactic acid is a styrene-based elastomer.   The resin composition according to any one of claims 12 and 13, wherein the copolymer (B) is a triblock copolymer containing an epoxy group.   It comprises a resin composition obtained by melt-kneading 30 to 99% by weight (A) of polylactic acid and 70 to 1% by weight (B) of a copolymer having a functional group reactive with the polylactic acid, The resin composition has a structure in which a reactive copolymer (B) is discontinuously dispersed as a dispersed phase having an average particle size ranging from 10 microns to 10 nanometers in a continuous phase composed of polylactic acid (A). And a broad halo diffraction pattern derived from an amorphous substance is dominant in the X-ray diffraction profile.   A molded body obtained by molding the resin composition according to claim 1.   The molded body according to claim 16, wherein the molding process is injection molding.   The molded body according to claim 16, wherein the molding process is press molding.   The molded body according to claim 16, wherein the molding process is extrusion molding.   The molded body according to claim 16, wherein the molding process is film molding.   The molded body according to claim 16, wherein the molded body has a film shape, a sheet shape or a plate shape.   The molded body according to claim 16, wherein a shape obtained by processing the molded body is a net shape, a fiber shape, a nonwoven fabric shape, a woven fabric shape, or a filament shape.   The molded body according to claim 16, wherein the molded body has a rod-like shape or an irregular shape.   The shaped body according to claim 16, wherein the shape of the shaped body is a tube, a tube, a bottle, or a columnar shape. The molded body is a container, a part for household appliances, a part for electric transmission, a housing material, a toy, a daily necessities, a material for agricultural and fisheries industry, a mobile device part, a packaging material, a medical part, or an automobile part. Molded body.