JP2009173715A - Polylactic acid-based sheet or film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polylactic acid-based sheet or film excellent in impact resistance, tear resistance, heat resistance, rigidity and transparency. <P>SOLUTION: A resin composition is prepared which comprises a polymer (A) consisting primarily of lactic acid, an aliphatic polyester (B) consisting primarily of an aliphatic carboxylic acid and a chain-molecular diol, and core-shell type rubber (C), wherein the total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is 30-80 pts.wt. based on 100 pts.wt. of the polymer (A), and the weight ratio of the aliphatic polyester (B) to the core-shell type rubber (C) is 30/70 to 70/30, provided that (B)+(C)=100. The resin composition is molded to obtain the objective sheet or film in which the aliphatic polyester (B) forms a fibril structure or a continuously ramified or netted three-dimensional structure in the polymer (A). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polylactic acid sheet or film excellent in impact resistance, tear resistance, heat resistance, rigidity, and transparency, and a method for producing the sheet or film.

  In recent years, biomass-derived plastics produced from raw materials derived from natural resources have attracted attention due to concerns such as global warming and depletion of petroleum resources. From the viewpoint of global environmental conservation, biodegradable plastics that are decomposed in the natural environment by the action of microorganisms existing in the soil and water are also attracting attention. Above all, polylactic acid is produced from starch such as corn, so it is a plastic that can circulate carbon dioxide (biomass-derived plastic) and is a plastic that can be decomposed in the natural environment (biodegradable plastic). It has attracted a lot of attention. However, polylactic acid sheets and films have the characteristics of being transparent and having high rigidity, but on the other hand, they have the disadvantages of low impact resistance, tear resistance, and heat resistance, and improvements are desired. .

As a method for improving the impact resistance of polylactic acid, there has been disclosed a method (Patent Document 1) in which a core-shell type rubber is added to polylactic acid as a multilayer structure polymer. By using this method, a modified olefin is added to polylactic acid. It is known that higher impact resistance can be obtained than a method of adding a compound (Patent Document 2) and a method of adding an aliphatic polyester other than polylactic acid and a modified olefin compound to a polylactic acid (Patent Document 3). . However, although the method of Patent Document 1 has a high impact resistance improvement effect, the tear resistance improvement effect is poor. In addition, in order to obtain impact resistance, a large amount of core-shell type rubber must be added, so that the degree of biomass origin and biodegradability, which are the characteristics of polylactic acid, decrease, transparency and rigidity There exists a problem that it falls and heat resistance is not improved.
Further, a method of using a crystal nucleating agent to improve the heat resistance (Patent Document 3) is disclosed, but this method has a drawback that the transparency is remarkably inferior.

JP 2003-286396 A JP 09-316310 A JP 2001-123055 A

  The present invention has been achieved as a result of studying the solution of the above-described problems in the prior art as an object, and the object is to provide impact resistance, tear resistance, heat resistance, rigidity, and transparency. The present invention relates to an excellent polylactic acid-based sheet or film, and a method for producing the sheet or film.

The present invention comprises a polymer (A) mainly composed of lactic acid, an aliphatic polyester (B) mainly composed of an aliphatic carboxylic acid and a chain molecular diol, and a core-shell type rubber (C). (A) The total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is 30 to 80 parts by weight with respect to 100 parts by weight, and the aliphatic polyester (B) and the core-shell type Resin composition whose weight ratio to rubber (C) is 30/70 to 70/30 (where (B) + (C) = 100) in the aliphatic polyester (B) / core-shell type rubber (C) A polylactic acid system characterized in that the aliphatic polyester (B) forms a three-dimensional structure in which the aliphatic polyester (B) is linked to a fibril structure or a branch or network in the polymer (A) It relates to a sheet or film.
Next, a polymer (A) mainly composed of lactic acid, an aliphatic polyester (B) mainly composed of an aliphatic carboxylic acid and a chain molecular diol, and a core-shell type rubber (C). (A) The total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is 30 to 80 parts by weight with respect to 100 parts by weight, and the aliphatic polyester (B) and the core-shell type Resin composition whose weight ratio to rubber (C) is 30/70 to 70/30 (where (B) + (C) = 100) in the aliphatic polyester (B) / core-shell type rubber (C) A polylactic acid sheet or film characterized in that the product is uniaxially or biaxially stretched to form the aliphatic polyester (B) into a fibril structure or a three-dimensional structure in which branches or networks are connected. Regarding the method.
Next, a polymer (A) mainly composed of lactic acid, an aliphatic polyester (B) mainly composed of an aliphatic carboxylic acid and a chain molecular diol, and a core-shell type rubber (C). (A) The total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is 30 to 80 parts by weight with respect to 100 parts by weight, and the aliphatic polyester (B) and the core-shell type Resin composition whose weight ratio to rubber (C) is 30/70 to 70/30 (where (B) + (C) = 100) in the aliphatic polyester (B) / core-shell type rubber (C) A polylactic acid sheet or film characterized in that a product is biaxially stretched and deformed by a calendar molding device or a roll molding device to form a three-dimensional structure in which the aliphatic polyester (B) is continuous or branched. It relates to the manufacturing method.

  The sheet or film of the present invention comprises an aliphatic polyester (A) having a main component of an aliphatic carboxylic acid and a chain molecular diol as a main component (A) (hereinafter also referred to as “polymer (A)”). B) (hereinafter also referred to as “aliphatic polyester (B)”) and core-shell type rubber (C) can be added to the polymer (A) without significantly impairing the transparency and rigidity of the polymer (A). The impact resistance, tear resistance, heat resistance, which are lacking in the above) are improved by the characteristics of the aliphatic polyester (B) and the core-shell rubber (C). It is a sheet or film that has both rigidity and transparency. Polylactic acid-based sheets or films can be obtained without using special molding conditions or molding equipment, so existing equipment can be used at low cost and efficiency. Well sheet or Film can be produced.

First, the polymer (A), aliphatic polyester (B), and core-shell type rubber (C) used in the present invention will be described.
As the polymer (A) of the present invention, a polymer generally called polylactic acid can be suitably used.
Polylactic acid is a thermoplastic resin that is substantially composed only of monomer units derived from L-lactic acid and / or D-lactic acid. Here, “substantially” means that other monomer units not derived from L-lactic acid or D-lactic acid may be included as long as the effects of the present invention are not impaired. As the production method, any known polymerization method can be employed. Most representatively known is a method of ring-opening polymerization of lactide, which is an anhydrous cyclic dimer of lactic acid (lactide method), but lactic acid may be directly subjected to condensation polymerization. The molecular weight is not particularly limited, but is usually 30,000 to 1,000,000 in terms of weight average molecular weight, and preferably in the range of 100,000 to 300,000. When the polymer containing lactic acid as a main component is composed only of monomer units derived from L-lactic acid and / or D-lactic acid, the polymer is crystalline and has a high melting point. L-lactic acid, D-lactic acid By changing the ratio of the derived monomer units, the crystallinity and melting point can be freely adjusted, so that the practical characteristics can be controlled according to the application.
In addition, the polymer (A) used in the present invention can be appropriately selected from polylactic acid according to the desired physical properties and applications. Further, two or more types of polylactic acid may be used in combination as necessary.

  Incidentally, some polymers (A) that can be used in the present invention are already on the market. Launched by Lacia (trade name) launched by Mitsui Chemicals, U'z (trade name) launched by Toyota Motor Corporation, Rakurie (trade name) launched by Fuji Chemical, and Unitika Ltd. In the present invention, such a polymer mainly composed of lactic acid can be suitably used.

Next, as the aliphatic polyester (B) of the present invention, a polymer generally referred to as an aliphatic polyester can be preferably used.
The aliphatic polyester is a polymer substantially obtained by polycondensation of an aliphatic dicarboxylic acid and a chain molecular diol. Here, “substantially” means that other monomer units not derived from the aliphatic dicarboxylic acid or the chain molecular diol may be included as long as the effects of the present invention are not impaired.
Specific examples of the aliphatic polyester include polyethylene adipate, polypropylene adipate, polybutylene adipate, polyhexene adipate, polybutylene succinate, polybutylene succinate adipate, and the like.
The molecular weight is 20,000 to 1,000,000 in terms of weight average molecular weight, but preferably in the range of 80,000 to 300,000 from the viewpoint of molding processability and physical properties of the obtained molded body. Is done.
The aliphatic polyester (B) used in the present invention can be appropriately selected from aliphatic polyesters according to the desired physical properties and applications. Moreover, you may combine 2 or more types of aliphatic polyester as needed.

  Incidentally, as the aliphatic polyester (B) that can be used in the present invention, there are those already on the market. Lunare SE (trade name) marketed by Nippon Shokubai, Bionore (trade name) marketed by Showa Polymer Co., Ltd., GSPla (trade name) marketed by Mitsubishi Chemical Co., Ltd. In the present invention, an aliphatic polyester mainly composed of such an aliphatic carboxylic acid and a chain molecular diol can be preferably used.

  Next, the core-shell type rubber (C) of the present invention is generally composed of a core layer composed of a polymer having rubber elasticity and one or more shell layers covering the core layer, which are adjacent to each other. A core-shell type rubber whose layer is composed of different polymers can be preferably used.

  The core layer of the core-shell type rubber may be a polymer composed of a component having rubber elasticity, for example, an acrylic component such as an ethyl acrylate unit or a butyl acrylate unit, a styrene unit or α-methylstyrene. Styrene components such as units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, nitrile components such as acrylonitrile units and methacrylonitrile units, conjugated diene components such as butadiene units and isoprene units, and urethane components. Coalescence is mentioned. Moreover, the copolymer comprised by combining 2 or more types of these components is also mentioned, for example, from acrylic components, such as an ethyl acrylate unit and a butyl acrylate unit, and silicone components, such as a dimethylsiloxane unit and a phenylmethylsiloxane unit. Copolymer composed, copolymer composed of acrylic component such as ethyl acrylate unit and butyl acrylate unit and styrene component such as α-methylstyrene unit, acrylic such as ethyl acrylate unit and butyl acrylate unit A copolymer composed of conjugated diene components such as butadiene units and isoprene units, acrylic components such as ethyl acrylate units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, and styrene units. And the like formed copolymer of styrene component such as α- methylstyrene units.

  In the present invention, a polymer or copolymer composed of the above components can be suitably used for the core layer of the core-shell type rubber (C). Especially, since it is excellent in impact resistance, the glass transition temperature of a polymer or a copolymer is preferably 20 ° C. or less, and more preferably 0 ° C. or less.

  As the shell layer of the core-shell type rubber, a polymer composed of a thermoplastic component and having a glass transition temperature higher than that of the core layer polymer is generally used. For example, thermoplastic polymers include unsaturated carboxylic acid alkyl ester units, glycidyl group-containing vinyl units, aliphatic vinyl units, aromatic vinyl units, vinyl cyanide units, maleimide units, Examples thereof include polymers obtained from saturated dicarboxylic acid units, unsaturated dicarboxylic acid anhydride units or other vinyl units.

  In the present invention, the above polymer can be suitably used for the shell layer of the core-shell type rubber (C). Of these, unsaturated carboxylic acid alkyl ester units, unsaturated glycidyl group-containing units and / or unsaturated dicarboxylic anhydrides are preferred from the viewpoints of adhesion and transparency with the polymer (A) and the aliphatic polyester (B). A polymer obtained from the unit is preferred, and a polymer obtained from the unsaturated carboxylic acid alkyl ester unit is more preferred. As the unsaturated carboxylic acid alkyl ester unit, (meth) acrylic acid alkyl ester is preferable, and methyl (meth) acrylate is more preferable because of excellent impact resistance.

  Preferable examples of the core-shell type rubber (C) of the present invention include acrylic core-shell type rubbers, styrene / butadiene type core-shell type rubbers, and silicone / acrylic type core-shell type rubbers. The core layer is butyl acrylate polymer, the shell layer is methyl methacrylate polymer, the core layer is butadiene / styrene polymer, the shell layer is methyl methacrylate polymer, the core layer is butyl acrylate / styrene copolymer Combined, shell layer is methyl methacrylate polymer, core layer is silicone-acrylic polymer, shell layer is methyl methacrylate polymer, core layer is silicone / acrylic copolymer, shell layer is methyl methacrylate / meta Examples thereof include a glycidyl acrylate copolymer.

  The average particle size of the core-shell type rubber (C) of the present invention is preferably from 0.01 to 100 μm, more preferably from 0.01 to 10 μm, more preferably from 0.01 to 10 μm, because of excellent impact resistance. A thickness of 01 to 3 μm is preferable.

  The weight ratio of the core layer to the shell layer of the core-shell type rubber (C) of the present invention is not particularly limited, but the core layer is 50 to 90% by weight with respect to the entire core-shell type rubber. It is preferable that it is 60 to 80% by weight.

  Incidentally, some core-shell type rubbers (C) that can be used in the present invention are already on the market. Marketed as Metabrene, marketed by Mitsubishi Rayon, Kaneace, marketed by Kaneka, Paraloid, marketed by Kureha, Staphyloid, marketed by Takeda Pharmaceutical, and Parapet, marketed by Kuraray In the present invention, such a core-shell type rubber can be preferably used.

  The total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is 30 to 80 parts by weight, preferably 30 to 70 parts by weight, based on 100 parts by weight of the polymer (A) used in the present invention. More preferably, it is 30-50 weight part. When the total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is less than 30 parts by weight, it becomes difficult to obtain an effect of improving impact resistance and tear resistance, and when it exceeds 80 parts by weight, the transparency is remarkably transparent. Becomes worse.

In the present invention, the weight ratio of the aliphatic polyester (B) to the core-shell type rubber (C) is 30/70 to 70/30, preferably 40 for the aliphatic polyester (B) / core-shell type rubber (C). / 60-60 / 40 (aliphatic polyester (B) + core-shell type rubber (C) = 100). The weight ratio of the aliphatic polyester (B) is lower than 30 and the core-shell type rubber (C) is higher than 70, or the weight ratio of the aliphatic polyester (B) is higher than 70 and the core-shell type rubber ( When C) is lower than 30, it becomes difficult to obtain a sheet or film having heat resistance, impact resistance, and tear resistance.
In the sheet or film of the present invention, it is preferable that at least 50% or more of the core-shell type rubber (C) contained in the composition is dispersed in the aliphatic polyester (B). Although it is not, it can be set as the sheet | seat or film which has high impact resistance and tear resistance by setting it as this form. That at least 50% or more of the core-shell type rubber (C) is dispersed in the aliphatic polyester (B) means that the polymer (A) is dissolved in the sheet or film of the present invention and the aliphatic polyester ( The weight of the undissolved component recovered after dipping in B) a solvent that cannot be dissolved is measured, and the value is [the blending amount of aliphatic polyester (B) + the blending amount of core-shell type rubber (C) × 0. .5].

  In the composition mainly composed of the polymer (A), the aliphatic polyester (B), and the core-shell type rubber (C), the aliphatic polyester (B) is a fibril structure or a branched structure in the polymer (A). Alternatively, in order to take a three-dimensional structure connected in a network, a composition mainly composed of the polymer (A), the aliphatic polyester (B), and the core-shell type rubber (C) is formed uniaxially or biaxially at the time of molding. It is preferable that the shaft is elongated and deformed.

  In the present invention, the uniaxial elongation deformation refers to a deformation mode described in “Rectology / Rheology” edited by the Japan Rheology Association. For example, a polymer composition (including a blend) is melted vertically, horizontally, and diagonally. And a method of stretching in any one direction. Specifically, molding (melt stretching) is performed by stretching a melt extruded from a die by a uniaxial or biaxial extrusion molding apparatus in either the flow direction (MD direction) or the direction perpendicular to the flow direction (TD direction). Can be mentioned.

  The term “melt” as used herein refers to a state in which a resin in a composition (including a blend) is melted. Specifically, a higher temperature of the melting temperature or glass transition temperature of the resin in the composition. This is the state described above (when the composition contains a plurality of resins, the melting temperature or the glass transition temperature of each of the resins contained in the composition is higher than the highest temperature). It refers to the state at a temperature that is not adversely affected by deterioration or the like. Also, melt stretching refers to stretching the melt.

  In the present invention, at the time of molding, in the polymer (A), the composition mainly composed of the polymer (A), the aliphatic polyester (B) and the core-shell type rubber (C) is uniaxially extended and deformed. The aliphatic polyester (B) can have a fibril structure.

  Here, the fibril structure is an incompatible resin mixed (polymer blend) body, and a spherical (or elliptical) minute phase of a resin having a low volume fraction (in the present invention, an aliphatic polyester (B)). The main (50% or more) form excluding the gel-like phase (foreign matter) is a rod-like piece or fiber, and is distributed substantially parallel to the outer surface (front and back planes) of the film or sheet. Point to.

  Although it does not specifically limit about the rod-shaped piece or fibrous fibril structure which aliphatic polyester (B) in the sheet | seat or film of this invention forms, Preferably it is 0.15 micrometer-10.0 micrometers, More preferably, it is 0.5-6. It is a rod-like piece or fibrous fibril structure having a thickness of 0.0 μm. When the thickness of the rod-like piece or fiber is less than 0.15 μm, the obtained sheet or film may be inferior in tear resistance and impact resistance, whereas when it exceeds 10.0 μm, the transparency is poor. It may get worse.

  The set temperature of the apparatus when the sheet or film of the present invention is uniaxially extended and deformed is preferably 150 to 250 ° C, more preferably 180 to 230 ° C. When the set temperature is less than 150 ° C., the viscosity at the time of melting is high and hard, so that processing may be difficult, and the obtained sheet or film may be inferior in surface smoothness. On the other hand, when the temperature exceeds 250 ° C., the viscosity at the time of melting is low and the fluidity is high, so that processing may be difficult, and thermal degradation may occur.

  The melt draw ratio when the sheet or film of the present invention is formed by uniaxial elongation deformation is preferably 200% to 3000%, more preferably 500 to 2000%. When a sheet or film is produced at a draw ratio of less than 200%, there is a possibility of transparency, impact resistance, tear resistance, and heat resistance. When a sheet or film is produced at a draw ratio of 3000% or more, stretch unevenness is produced. May occur, and it may be difficult to obtain a sheet or film having a uniform thickness. Here, the draw ratio in the case of melt stretching refers to 100 × [thickness of sheet or film before melt stretching] / [thickness of sheet or film after melt stretching].

  Although the thickness of the sheet | seat or film obtained by shaping | molding by the uniaxial extension deformation | transformation of this invention is not specifically limited, Less than 1.00 mm is preferable, More preferably, it is 0.50 mm or less, More preferably, it is 0.30 mm or less. When the thickness of the sheet or film is 1 mm or more, the surface smoothness of the sheet or film is inferior. When obtaining a sheet or film having a thickness of 1.0 mm or more, it is preferable to produce a sheet or film by laminating a plurality of sheets having a thickness of less than 1.00 mm. On the other hand, the lower limit of the thickness is preferably 0.01 mm or more, more preferably 0.03 mm or more in consideration of workability and thickness uniformity, although it depends on the molding apparatus.

  The biaxial elongation deformation in the present invention refers to a deformation mode described in “Rectology / Rheology” edited by the Japan Rheology Association, and for example, a polymer composition (including a blend) is formed into a gap such as a roll. And forming a molten resin pool (usually referred to as a bank) and rolling through a gap narrower than the formed bank. Specifically, molding by a roll molding device, a calendar molding device, an extrusion molding device equipped with a facility for rolling molten resin extruded from a die with a roll, the flow direction (MD direction) of the molten resin extruded from a die, and Examples include molding that simultaneously extends in the flow direction height and the vertical direction (TD direction). In calendar molding or roll molding, the molten resin is stretched two-dimensionally simultaneously in the roll axis direction (TD direction) and in the direction perpendicular to the roll axis direction (roll gap traveling direction, MD direction) as it passes through the bank. As a result, the melt is deformed biaxially.

  In the present invention, at the time of molding, the polymer (A), the aliphatic polyester (B), and the core-shell type rubber (C) as a main component are biaxially stretched and deformed, whereby the polymer (A) Thus, the aliphatic polyester (B) can have a three-dimensional structure connected in a branch or network.

  Here, the three-dimensional structure connected in the form of branches or networks generally means that the resin component contained in the composition is thermally measured (for example, measured by a differential scanning calorimeter) or viscoelastic. Even in a state where a sea-island structure is formed by a measurement method (for example, measurement by dynamic viscoelasticity), an observation method by a microscope (observation by a scanning electron microscope or a transmission electron microscope), etc. Instead, each resin component indicates a state in which a three-dimensionally continuous structure is formed in the molded body, and the present concept is applied also in the present invention.

  The three-dimensional structure connected to the branch or network formed by the aliphatic polyester (B) in the sheet or film of the present invention is not particularly limited, but is preferably 0.3 μm to 10.0 μm, more preferably 0.00. A structure in which branches or spherical particles are continuously connected three-dimensionally with a thickness of 5 to 6.0 μm is preferable. When the thickness of the structure in which the branch-like or spherical particles are continuously linked three-dimensionally is less than 0.3 μm, the obtained sheet or film may be inferior in heat resistance and tear resistance, whereas 10 When the thickness exceeds 0.0 μm, the transparency may be deteriorated.

  150-230 degreeC is preferable and, as for the preset temperature of the apparatus at the time of shaping | molding the sheet | seat or film of this invention by biaxial expansion | extension deformation, 170-200 degreeC is preferable. When the set temperature is less than 150 ° C., the viscosity at the time of melting is high and hard, so that processing may be difficult, and the obtained sheet or film may be inferior in surface smoothness. On the other hand, when the temperature exceeds 230 ° C., the viscosity at the time of melting is low and the fluidity is high, so that the processing may become difficult, and further heat deterioration may occur.

When the sheet or film of the present invention is produced by an apparatus for molding by biaxial elongation deformation, a thinner sheet or film can be produced efficiently by melt-drawing in at least one direction.
The stretch ratio in the case of melt stretching is preferably 120 to 500%, more preferably 130 to 400%, and still more preferably 150 to 350%. When a sheet or film is produced at a draw ratio of less than 120%, the improvement in production efficiency by melt-drawing is poor, and when a sheet or film is produced at a draw ratio of 500% or more, stretching unevenness occurs. It may be difficult to obtain a sheet or film having a uniform thickness. Here, the draw ratio in the case of melt stretching refers to 100 × [thickness of sheet or film before melt stretching] / [thickness of sheet or film after melt stretching].

  The thickness of the sheet or film obtained by forming by biaxial elongation deformation of the present invention is not particularly limited, but is preferably less than 1.00 mm, more preferably 0.50 mm or less, and even more preferably 0.30 mm or less. . When the thickness of the sheet or film is 1 mm or more, the surface smoothness of the sheet or film may be inferior. When obtaining a sheet or film having a thickness of 1.0 mm or more, it is preferable to produce a sheet or film by laminating a plurality of sheets or films having a thickness of less than 1.00 mm. On the other hand, although the lower limit of the thickness depends on the molding apparatus, it is preferably 0.03 mm or more, and more preferably 0.05 mm or more in consideration of workability and thickness uniformity.

  In the composition mainly comprising the polymer (A), the aliphatic polyester (B) and the core-shell type rubber (C) of the present invention, the aliphatic polyester (B) is a fibril structure in the polymer (A). Alternatively, when forming a sheet or film having a three-dimensional structure connected in a branch or network, biaxial stretching deformation is preferable from the viewpoint of transparency and impact resistance, and the forming apparatus produces a sheet or film. From the viewpoint of the speed to perform and the thickness accuracy of the obtained sheet or film, a roll forming apparatus and a calendar forming apparatus are preferable.

In the composition (A), the aliphatic polyester (B) and the core-shell type rubber (C) used as main components in the present invention, and the sheet or film of the present invention, if necessary, Hindered phenol-based, thioether-based, amine-based, phosphorus-based antioxidants, plasticizers, inorganic fillers, UV absorbers, light stabilizers, UV shielding agents, antistatic agents, flame retardants, anti-coloring agents, increase You may add the other compounding agents generally added to resin, such as a sticky agent, an antibacterial agent, an antifungal agent, surfactant, a fluorescent agent, and a crosslinking agent.
If necessary, a lubricant generally added to the resin can be used alone or in combination. The type of lubricant is not particularly limited, but when the sheet or film of the present invention is molded, deterioration or evaporation may occur depending on the molding conditions, and the molding process may be difficult. It is preferable to blend a fatty acid and / or a fatty acid ester having 20 or more carbon atoms and / or a fatty acid metal salt having 20 or more carbon atoms. Specific examples include behenic acid, behenic acid ester, calcium behenate, zinc behenate, magnesium behenate, lithium behenate, montanic acid, montanic acid ester, sodium montanate, calcium montanate, and magnesium montanate. .

  The blending amount of the lubricant is added within a range that does not impair the mechanical properties of the molded article to be obtained. Usually, it is 0.1 to 5 parts by weight, preferably 0 to 100 parts by weight of the resin constituting the molded article. 0.5 to 2 parts by weight, and a composition comprising a polymer (A), an aliphatic polyester (B) and a core-shell type rubber (C) used in the present invention as main components (the resin constituting the molded product is The same applies to the weight parts of the polymer (A), the aliphatic polyester (B) and the core-shell type rubber (C).

  When pre-kneading is necessary for obtaining the sheet or film of the present invention, a known apparatus usually used in thermoplastic resins can be used. For example, a polymer (A), an aliphatic polyester (B), a core-shell type rubber (C), and those to which compounding agents such as a lubricant and an antioxidant are added as necessary are a high-speed stirrer, a low-speed stirrer, a Henschel It may be mixed uniformly with a mixer, melt-mixed with a batch-type kneading mixer, Banbury mixer, kneader, extruder, etc., and molded immediately. Moreover, after melt mixing, it may be once pelletized and then molded.

  The sheet or film of the present invention is preferably melt-stretched as necessary, and then cooled by contacting with a drum or the like. The set temperature of the drum to be cooled is preferably 30 to 120 ° C, more preferably 40 to 100 ° C, and still more preferably 50 to 80 ° C. If the temperature is higher than 120 ° C, cooling may be insufficient and the molded sheet or film may shrink or stretch. If the temperature is lower than 30 ° C, the sheet or film may be wrinkled due to rapid cooling or molding. It is not preferable because there is a possibility of cutting inside.

  The sheet or film of the present invention is subjected to melt stretching as necessary after uniaxial stretching deformation or biaxial stretching deformation, and after cooling, stretched at a temperature not lower than the glass transition temperature of the polymer (A) and lower than the melting temperature ( (Cold drawing) may be used. The draw ratio (cold draw ratio) at this time is 101% or more and less than 150%, preferably 103% or more and less than 130%, and more preferably 105% or more and less than 120%. When the cold draw ratio is less than 101%, sagging may occur in the sheet or film during molding. When the draw ratio is 150% or more, the film is oriented and the tear strength in the length direction becomes weak, or the drawing unevenness Occurs, and a sheet or film with a uniform thickness cannot be obtained, or the sheet or film may be cut or broken during production. The term “cold drawing ratio” as used herein means 100 × [thickness of sheet or film before cold drawing] / [thickness of sheet or film after cold drawing].

  The sheet or film of the present invention may be subjected to a surface treatment generally performed in order to improve printability, laminating properties, and coating suitability. Examples of the surface treatment method include corona discharge treatment, plasma treatment, and acid treatment.

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
First, materials used in Examples or Comparative Examples will be described below, and then the present invention will be described more specifically with Examples and Comparative Examples.

<Polymer (A)>
A-1: Polylactic acid resin in pellet form with a glass transition point of 63 ° C. and a melting point of 156 ° C. in DSC method and MFR (190 ° C., under 2.16 kg load) = 2.4 (g / 10 min) (trade name Lacia H -440, manufactured by Mitsui Chemicals, Inc.)
A-2: Polylactic acid resin in the form of pellets having a glass transition point of 63 ° C. and a melting point of 175 ° C. in the DSC method and MFR (190 ° C. under 2.16 load) = 3.5 (g / 10 min) (trade name U ′ z S-06, manufactured by Toyota Motor Corporation)
A-3: Polylactic acid resin in pellet form with MFR (190 ° C., under 2.16 kg load) = 2.5 (g / 10 min) at a glass transition point of 63 ° C. in DSC method (trade name Lacia H-280, Mitsui) (Chemical company)

<Aliphatic polyester (B)>
B-1: Pellet-shaped polyester resin having a glass transition point in the DSC method of −32 ° C. and a melting point of 115 ° C. and MFR (190 ° C. under a load of 2.16 kg) = 4.5 (g / 10 minutes) (trade name; (GSPlaAZ91T, manufactured by Mitsubishi Chemical Corporation)
B-2: Polyester resin in pellet form with MFR (190 ° C. under 2.16 kg load) = 20.0 (g / 10 min) at a glass transition point of −32 ° C. and a melting point of 115 ° C. in the DSC method (trade name; (GSPlaAZ71T, manufactured by Mitsubishi Chemical Corporation)

<Core-shell type rubber (C)>
C-1: Acrylic core-shell type rubber (trade name; Parapet SA, manufactured by Kuraray Co., Ltd.)
C-2: Acrylic core-shell type rubber (trade name; Methabrene W-341, manufactured by Mitsubishi Rayon Co., Ltd.)
C-3: Styrene / butadiene core-shell type rubber (trade name; Kane Ace B11A, manufactured by Kaneka Chemical Co., Ltd.)

<Lubricant (D)>
D-1: Montanic acid (trade name; Licowax S, manufactured by Clariant Japan)
<Antioxidant (E)>
E-1: Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate] methane (trade name; ADK STAB AO-60, manufactured by Asahi Denka Co., Ltd.)

<Examples 1 to 10, Comparative Examples 1 to 11> (Roll molding)
A compound consisting of the polymer (A), aliphatic polyester (B), core-shell type rubber (C), lubricant (D), and antioxidant (E) shown in Tables 1 to 4 has a capacity of 100 cc (0 (.0001 cubic meter) batch-type mixer for 5 minutes. Next, after rolling using a 10-inch (diameter 0.254 m) two-roll molding apparatus set at 180 ° C., melt stretching was immediately performed at a stretch ratio of 300% to prepare a sheet having a thickness of 100 μm. Here, the draw ratio refers to 100 × [thickness of sheet or film before melt drawing] / [thickness of sheet or film after melt drawing].

<Example 11> (Calendar molding)
A blend of polymer (A), aliphatic polyester (B), core-shell rubber (C), lubricant (D), and antioxidant (E) shown in Table 2 is uniformly mixed with a Henschel mixer. After that, the mixture was kneaded with a Banbury mixer until the resin temperature was within a range of 170 ° C. This was rolled using an inverted L-shaped four-calender molding device set at 180 ° C., and immediately subjected to melt drawing at a draw ratio of 300% to produce a sheet having a thickness of 100 μm. Here, the draw ratio refers to 100 × [thickness of sheet or film before melt drawing] / [thickness of sheet or film after melt drawing].

<Example 12> (extrusion molding)
After dry blending the blend of polymer (A), aliphatic polyester (B), core-shell rubber (C), lubricant (D), and antioxidant (E) shown in Table 2, 180 ° C. Melt-mixing pelletizing was performed using a twin-screw extrusion molding apparatus set to 1.
The obtained pellets were melt-kneaded using a T-die uniaxial extrusion molding apparatus set at 180 ° C. and immediately melt-stretched to 1500% to prepare a sheet having a thickness of 100 μm.

<Comparative Example 12> (Press molding)
The capacity | capacitance which set the compound (A) shown in Table 4, the aliphatic polyester (B), the core-shell type rubber (C), the lubricant (D), and the antioxidant (E) to 180 ° C. It was melt-kneaded with a 100 cc (0.0001 cubic meter) batch mixer for 5 minutes. Subsequently, using a compression molding machine, it heated at 180 degreeC for 10 minute (s), after compression, it cooled at 30 degreeC for 5 minutes, and produced the sheet | seat of thickness 100 micrometers.

<Heat resistance>
For Examples 1 to 12 and Comparative Examples 1 to 12, a 150 mm square sheet was cut out from the obtained sheet, and the sheet was heat treated in an oven set at 100 ° C. for 20 minutes, and then taken out before and after the heat treatment. The heat shrinkage rate was determined from the change in length in the sheet length direction (MD direction). About Comparative Example 12, since there is no distinction between the length direction (MD) and the width direction (TD), Examples 1 to 12 and Comparative Examples 1 to 12 and Evaluation was performed in the same manner. About the result, the case where the heat shrinkage rate is less than 5.0% is evaluated as ◯, the case where it is 5.0% or more and less than 10.0% is evaluated as Δ, and the case where it is 10.0% or more is evaluated as ×, and each is described in the table. did.

<Impact resistance>
It measured with the film impact tester by Toyo Seiki Co., Ltd. using the obtained sheet | seat.

<Tear strength>
About Examples 1-12 and Comparative Examples 1-12, about the length direction (MD) according to JIS K-7128 by the Toyo Seiki Seisakusho make and an Elmendorf tear tester using the obtained sheet | seat, respectively. It was measured. About Comparative Example 12, since there was no distinction between the length direction (MD) and the width direction (TD), it was evaluated in the same manner as Examples 1 to 12 and Comparative Examples 1 to 12 except that measurement was performed only in one direction. .

<Tensile modulus>
About Examples 1-12 and Comparative Examples 1-12, the sheet length direction (MD direction) in the form based on JIS K-7127 by the Toyo Seiki Seisakusho make and the Tensilon tensile tester using the obtained sheet | seat. The tensile elastic modulus was measured. About Comparative Example 12, since there is no distinction between the length direction (MD) and the width direction (TD), Examples 1 to 12 and Comparative Examples 1 to 12 are performed except that measurement is performed in only one direction without distinguishing the direction. And evaluated in the same manner.

<Transparency> (Haze)
Using the obtained sheet, it was measured with Nippon Denshoku Industries Co., Ltd., HazeMeter NDH2000. In order to remove the influence of external haze, the sample was put into a square quartz cell filled with liquid paraffin.

<Test Example 1>
About 0.02 g of the sheet obtained in Examples 1 to 12 was placed in 20 g of a 60/40 (w / w) solution of chloroform (for high performance liquid chromatography manufactured by Kanto Chemical Co., Ltd.) / Acetone (special grade manufactured by Kanto Chemical Co., Ltd.). As a result of immersing and observing the form after 24 hours, the sheet obtained in Examples 1 to 11 was a sheet, and the sheet obtained in Example 12 was a fiber. After taking out the sheet-like material and the fibrous material remaining in the solvent, drying at room temperature for 3 days, and measuring the weight, both are shown in Tables 1 and 2 [Amount of aliphatic polyester (B) + The amount of the core-shell type rubber (C) x 0.7] was almost the same.
Next, the dried sheet-like material is DSC (model; Pyris1, manufactured by Perkin Elmer).
First step: room temperature → (80 ° C./min)→200° C. (holding 5 min)
Second step: 200 ° C. → (40 ° C./min)→−40° C.
Third step: −40 ° C. → (10 ° C./min)→200° C.
As a result of the measurement by raising and lowering the temperature under the conditions, only the melting peak derived from the aliphatic polyester (B) was observed in the third step.
By the way, about 0.02 g of the sheet obtained in Comparative Example 2 was immersed in 20 g of a 60/40 (w / w) solution of chloroform / acetone, and the form after 24 hours was observed. The obtained sheet was a sheet-like material similar to the sheets obtained in Examples 1 to 11. The sheet-like material remaining in the solvent was taken out, dried at room temperature for 3 days, and then weighed. As a result, all agreed with the amount of the aliphatic polyester (B) shown in Table 3.
And the above-mentioned dried sheet-like material is DSC (model: Pyris1, manufactured by Perkin Elmer),
First step: room temperature → (80 ° C./min)→200° C. (holding 5 min)
Second step: 200 ° C. → (40 ° C./min)→−40° C.
Third step: −40 ° C. → (10 ° C./min)→200° C.
As a result of the measurement by raising and lowering the temperature under the conditions, all the sheet-like materials were observed only in the melting peak derived from the aliphatic polyester (B) in the third step, and the sheet-like materials were the aliphatic used in Comparative Example 2. The polyester (B) was continuous.
On the other hand, about 0.02 g of the sheet obtained in Comparative Example 3 was immersed in 20 g of a 60/40 (w / w) solution of chloroform / acetone, and the form after 24 hours was observed. As a result, the sheet shape was maintained. There wasn't.
From the experimental example of the sheet obtained in Comparative Example 2 and the experimental example of the sheet obtained in Comparative Example 3, the sheet-like material remaining after the solvent immersion in the experimental example of the sheet obtained in the previous Examples 1 to 11 is It can be said that this is a sheet in which an amount exceeding 50% of the blended amount of the core-shell type rubber (C) is dispersed in the continuously continuous aliphatic polyester (B). Further, in the experimental example of the sheet obtained in Example 12, the fibrous material remaining after the solvent immersion exceeds 50% of the blending amount of the core-shell type rubber (C) in the fibrous aliphatic polyester (B). It can be said that it is a fibrous material in which the amount is dispersed.

<Test Example 2>
After the solvent immersion test carried out in Test Example 1, the sheet and fibrous material remaining in the solvent were taken out and washed three times with a solution of chloroform / acetone = 60/40 (w / w). After being immersed for a period of time, it was taken out from the methanol solution, dried at room temperature for 3 days, and observed with a scanning electron microscope (SEM).
As a result, a three-dimensional structure in which all the sheet-like materials remaining undissolved in Examples 1 to 11 were connected in a branch shape or a net shape was observed. In addition, after the solvent immersion test of the sheet obtained in Example 2, a scanning electron micrograph at a magnification of 3,500 times of the sheet-like material (sheet washed and dried by the above-described method) remaining in the solvent is shown in FIG. Shown in
Further, fibrils were observed in the fibrous material remaining undissolved in Example 12. In addition, after the solvent immersion test of the sheet obtained in Example 12, a scanning electron micrograph at a magnification of 3,500 times of the fibrous material (sheet washed and dried by the above-described method) remaining in the solvent is shown in FIG. Shown in

<Comparative Test Example 1>
As a result of immersing about 0.02 g of the sheet obtained in Comparative Example 12 in 20 g of a 60/40 (w / w) solution of chloroform / acetone and observing the form after 24 hours, the sheet could not keep its shape. , Has fallen apart. The components that could not retain their shape in the solvent were recovered and dried at room temperature for 3 days and then weighed. As a result, the aliphatic polyester (B) and the core-shell rubber (shown in Table 4) About 80% of the combined amount of C).
Next, the dried product of the above-described floating component was obtained by DSC (model: Pyris1, manufactured by Perkin Elmer).
First step: room temperature → (80 ° C./min)→200° C. (holding 5 min)
Second step: 200 ° C. → (40 ° C./min)→−40° C.
Third step: −40 ° C. → (10 ° C./min)→200° C.
As a result of the measurement by raising and lowering the temperature under the conditions, only the melting peak derived from the aliphatic polyester (B) was observed in the third step, and the aliphatic polyester (B) was present in a discontinuous state. It was.

<Comparative Test Example 2>
After the solvent immersion test performed in Comparative Test Example 1, the components that could not retain their shape in the solvent and were suspended were collected, washed three times with a solution of chloroform / acetone = 60/40 (w / w), and methanol. After being immersed in the solution for 24 hours, it was recovered from the methanol solution, dried at room temperature for 3 days, and observed with a scanning electron microscope (SEM).
As a result, the component that could not retain its shape in the solvent and floated was particles having a diameter of 5 to 30 μm, and in the sheet prepared in Comparative Example 12, the aliphatic polyester (B) did not form a continuous phase, It was present in the form of particles.

  The sheet or film of the present invention maintains the rigidity and transparency of the polymer (A) by adding the aliphatic polyester (B) and the core-shell rubber (C) to the polymer (A). Impact resistance, tear resistance and heat resistance, which are lacking in the coalescence (A), are improved by the characteristics of the aliphatic polyester (B) and the core-shell type rubber (C). It is a sheet or film that combines heat resistance, rigidity, and transparency. Polylactic acid-based sheets or films can be obtained efficiently and inexpensively using existing equipment without using special molding conditions or molding equipment. Therefore, it can be widely used as a sheet or film for cosmetics for building materials, packaging, display labels, and the like.

It is a scanning electron micrograph of the magnification of 3,500 times of the sheet-like thing which remained in the solvent after the solvent immersion test of the sheet | seat obtained in Example 2. FIG. It is a scanning electron micrograph of the magnification of 3,500 times of the fibrous material which remained in the solvent after the solvent immersion test of the sheet | seat obtained in Example 12. FIG.

Claims (3)

  A polymer (A) mainly composed of lactic acid, an aliphatic polyester (B) mainly composed of an aliphatic carboxylic acid and a chain molecular diol, and a core-shell rubber (C). The total amount of the aliphatic polyester (B) and the core-shell type rubber (C) is 30 to 80 parts by weight with respect to 100 parts by weight, and the aliphatic polyester (B) and the core-shell type rubber (C ) And a resin composition having a weight ratio of 30/70 to 70/30 ((B) + (C) = 100) of the aliphatic polyester (B) / core-shell type rubber (C) The poly (lactic acid) -based sheet or film, wherein the aliphatic polyester (B) forms a fibril structure or a three-dimensional structure connected in a branch or network form in the polymer (A). .   The resin composition according to claim 1 is uniaxially or biaxially stretched to form the aliphatic polyester (B) into a fibril structure or a three-dimensional structure connected in a branch or network form. A method for producing a polylactic acid-based sheet or film.   The resin composition according to claim 1 is biaxially stretched and deformed by a calender molding apparatus or a roll molding apparatus to form a three-dimensional structure in which the aliphatic polyester (B) is continuous in a branch or network. The method for producing a polylactic acid sheet or film according to claim 2.

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