JP2009242596A - Thermoplastic resin composition and film or sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film or a sheet excellent in whitening resistance and strength. <P>SOLUTION: The thermoplastic resin composition comprises a 5-95 wt.% polylactic acid resin (A) and a 95-5 wt.% copolymer (B) obtained by polymerization of a monomer mixture comprised of butyl(meth)acrylate and/or butadiene of 5-40 wt.% with at least one sort of monomer of 95-60 wt.% selected from acrylonitrile, styrene, α-methyl styrene, phenyl methacrylate, methyl methacrylate, maleimide, N-phenyl maleimide, N-cyclohexyl maleimide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin composition. More specifically, the present invention relates to a film or sheet comprising the thermoplastic resin composition, which is excellent in low whitening property and excellent in film strength.

Since polyethylene terephthalate (hereinafter referred to as PET) is excellent in transparency and strength, it is used as an optical component such as a PET bottle, various packaging materials, a polarizing plate or a diffusion plate.
However, although PET is excellent in transparency and strength, it is inferior in moldability, printing characteristics or adhesiveness, and further, the molded product can be easily deformed depending on use conditions due to insufficient heat resistance, and the molding cycle is long. It is known to have the disadvantages.
To solve these problems, it has been proposed to add a crystal nucleating agent that promotes crystallization, or to alloy with other polyester resins (for example, polybutylene terephthalate or polycarbonate resin) or ABS resin. Due to the problem of deterioration in characteristics, the problem has not been solved sufficiently.
In addition, PET is used for various packaging materials and industrial products from the viewpoint of punching workability or low whitening property, but problems such as poor surface hardness and weather resistance have been pointed out. On the other hand, as other transparent resins, polymethyl methacrylate resin and polycarbonate resin, methyl methacrylate-styrene copolymer, acrylonitrile-styrene copolymer, polystyrene, etc. are known, but its cost and punching workability, Or the present condition is that there is no material which replaces PET from the point of low whitening property, such as bending whitening property.
On the other hand, in recent years, as an environmental problem on a global scale, the future of petroleum resources due to increased use of petrochemical products has been threatened. For example, a polylactic acid resin is a resin made of lactic acid obtained from plant corn and potatoes as a raw material, and is known as an environmentally friendly resin that does not use petroleum as a raw material. However, the polylactic acid resin has a drawback that it is inferior in moldability and strength in film or sheet molding.
JP 2004-292547 A JP 2002-194167 A JP 2004-189833 A JP 2007-246678 A

  The objective of this invention is providing the film or sheet | seat which is excellent in low whitening property and has favorable intensity | strength.

  That is, the present invention comprises polylactic acid resin (A) 5 to 95% by weight, butyl (meth) acrylate and / or butadiene 5 to 40% by weight, acrylonitrile, styrene, α-methylstyrene, phenyl methacrylate, methyl methacrylate, maleimide, From 95 to 5% by weight of copolymer (B) obtained by polymerizing a monomer mixture consisting of 95 to 60% by weight of at least one monomer selected from N-phenylmaleimide and N-cyclohexylmaleimide A thermoplastic resin composition, and a film or sheet comprising the thermoplastic resin composition.

  The film or sheet of the present invention is low in cost, excellent in whitening properties and excellent in strength, and can be effectively used as various packaging materials and various industrial products.

Hereinafter, the present invention will be described in detail.
The polylactic acid (A) in the present invention means polylactic acid and a copolymer of lactic acid and hydroxycarboxylic acid. Starch obtained from plants such as corn is fermented into lactic acid and polymerized by chemical synthesis.
Examples of lactic acid include L- and / or D-lactic acid, lactone which is a dimer of lactic acid, and the like. Furthermore, examples of the hydroxycarboxylic acid copolymerizable with lactic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, and hydroxycaproic acid, and one or more can be used.
In the present invention, commercially available poly L-lactic acid is preferred.
The molecular weight of polylactic acid is not particularly limited, but the weight average molecular weight is preferably 30,000 or more from the viewpoint of physical and thermal properties.
Polylactic acid is marketed under the names of “LACEA” manufactured by Mitsui Chemicals, “Nature Works” manufactured by Nature Works LLC of the United States, “Terramac” manufactured by Unitika, “Ecodia” manufactured by Toray Industries, and “Ecorouge” manufactured by Mitsubishi Plastics. You can use what you have.

The copolymer (B) in the present invention contains 5 to 40% by weight of butyl (meth) acrylate and / or butadiene, acrylonitrile, styrene, α-methylstyrene, phenyl methacrylate, methyl methacrylate, maleimide, N-phenylmaleimide, N -A copolymer obtained by polymerizing a monomer mixture consisting of 95 to 60% by weight of at least one monomer selected from cyclohexylmaleimide, and having a glass transition temperature of 40 ° C or higher.
Less than 5% by weight of butyl (meth) acrylate and / or butadiene (at least one selected from acrylonitrile, styrene, α-methylstyrene, phenyl methacrylate, methyl methacrylate, maleimide, N-phenylmaleimide, N-cyclohexylmaleimide) When the monomer exceeds 95% by weight, sufficient punching strength cannot be obtained, and butyl (meth) acrylate and / or butadiene exceeds 40% by weight (acrylonitrile, styrene, α-methylstyrene, phenyl methacrylate, methyl). (At least one monomer selected from methacrylate, maleimide, N-phenylmaleimide and N-cyclohexylmaleimide is less than 60% by weight) and the rigidity required for the final product tends to be insufficient.
Moreover, there is no restriction | limiting about the glass transition temperature of the copolymer in this invention, However, It is preferable that it is 20 degreeC or more, and it is especially preferable that it is 30-120 degreeC from the point of coloring of a final product or a moldability.
In addition, about glass transition temperature, it is possible to adjust arbitrarily by the kind and usage ratio of the monomer used above. The glass transition temperature was measured using a differential scanning calorimeter (DSC6200) manufactured by Seiko Instruments Inc. under conditions of a starting temperature of 50 ° C. and a heating rate of 2 ° C./min under a nitrogen stream.

  In the copolymer (B), it is also possible to use other vinyl monomers within a range that does not impede its purpose. Examples of such other vinyl monomers include ethyl (meth) acrylate, propyl (meth) acrylate 2-ethylexyl acrylate, methacrylonitrile, ethacrylonitrile, fumaronitrile, divinylbenzene, N-hexylmaleimide, anhydrous Examples include maleic acid, acrylic acid, methacrylic acid and the like.

  The copolymer (B) in the present invention preferably has a number average polystyrene-reduced molecular weight of 20,000 or more and a molecular weight distribution (Mw / Mn) of less than 3.0 from the viewpoint of moldability or the strength of the final product. About these number average polystyrene conversion molecular weight and molecular weight distribution, it is possible to change the reaction temperature and time at the time of polymerization, the addition amount of additives such as an initiator during polymerization, and the like. In addition, the number average polystyrene conversion molecular weight and molecular weight distribution can be measured using general GPC (gel permeation chromatography).

  The copolymer (B) in the present invention can be produced by a known polymerization method such as an emulsion polymerization method, a suspension polymerization method, a solution polymerization method or a bulk polymerization method.

In the present invention, if the copolymer (B) contains a large amount of volatile components at 200 ° C., it may cause eye cracks during film or sheet processing and easily cause defects that impair the appearance of the product. Therefore, the amount of volatile components is preferably less than 0.2% by weight. The amount of volatile components is adjusted by, for example, stripping operation at the end of polymerization or using a vented granulator as a granulator during granulation, and changing granulation conditions such as granulation temperature and discharge rate. Is possible.
The amount of volatile components was TG / DTA 6300 manufactured by Seiko Instruments Inc., and the weight loss at 200 ° C. when the temperature was raised under the measurement conditions of 50 ° C. and 2 ° C./min under nitrogen flow. It was determined by measuring the rate.

  The thermoplastic resin composition in the present invention comprises the polylactic acid resin (A) 5 to 95% by weight and the copolymer (B) 95 to 5% by weight. If the polylactic acid resin (A) is less than 5% by weight, the moldability tends to be inferior, and if it exceeds 95% by weight, sufficient strength required for the final product tends not to be obtained. The polylactic acid resin (A) is preferably in the range of 20 to 80% by weight.

In the thermoplastic resin composition of the present invention, benzotriazole ultraviolet absorbers such as Tinuvin P, 234, 326, 329, 360 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Sumisorb 100, 110, 130 (Sumitomo Chemical Co., Ltd.) Benzophenone-based ultraviolet absorbers such as Sumisorb 400 (manufactured by Sumitomo Chemical Co., Ltd.), Adekastab LA-77 (manufactured by Asahi Denka Kogyo Co., Ltd.), Uvinul 4050H, 5050H (manufactured by BASF) It is possible to add one or more hydrolysis stabilizers such as a light stabilizer selected from hindered amine light stabilizers such as polycarbodiimide.
Furthermore, inorganic fine particles such as silica, barium sulfate, calcium carbonate, etc., organic cross-linked fine particles made of methacrylic resin, silicon resin, etc., other dyes, pigments, lubricants, flame retardants, mold release agents and antioxidants are added according to the purpose. It is also possible to do.

The film or sheet molded product in the present invention is prepared by directly feeding the polylactic acid (A) and the copolymer (B) into a molding machine, or the polylactic acid (A) and the copolymer (B) are prepared in a usual manner. After melt-kneading using a granulator (for example, Banbury, roll, single-screw extruder, twin-screw extruder, etc.), a molding machine suitable for the purpose such as an inflation molding machine, a calendar molding machine, a sheet extruder, a film extruder, etc. Can be created using. Moreover, it is also possible to make a multilayer film or a multilayer sheet with other resins by a multilayer molding machine or a laminate method.
The molding temperature is preferably 160 to 280 ° C. If the molding temperature is less than 160 ° C, the molding machine is not sufficiently melted, and the molding machine is likely to be burdened. If the molding temperature exceeds 280 ° C, it tends to cause discoloration or appearance defects due to contamination by burnt foreign matter.

Furthermore, in the present invention, it is preferable that there are less than 20 defects (foreign substances such as polymer aggregates contained in the film or sheet) having a diameter of 100 to 500 μm per 1 m ² of the obtained film or sheet. The number of the disadvantages is that a granulator or a molding machine is particularly suitable for adjusting reaction conditions such as reaction temperature and reaction time during the polymerization of the copolymer (B), or when granulating or molding the composition of the present invention. It is possible to adjust by attaching a filter (for example, a metal mesh or a sintered filter).

  Specific uses of the sheet / film molded article of the present invention include packaging materials such as food packaging and seal laminate, various industrial materials such as magnetic tapes and capacitors, diffusion plates and polarizing plates, masking films and release papers.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not restrict | limited at all by these.

〔Example〕
-Polylactic acid resin (A)-
Polylactic acid resin A-1: LACEA H-400 manufactured by Mitsui Chemicals, Inc. was used.

-Copolymer (B)-
Copolymer B-1: A monomer mixture comprising 35 parts by weight of butyl acrylate, 15 parts by weight of acrylonitrile, 50 parts by weight of styrene, and 0.03 parts by weight of t-dodecyl mercaptan was polymerized by a known bulk polymerization method. . Subsequent to polymerization, the polymerization liquid continuously extracted from the reaction vessel is supplied to a devolatilizer to separate volatile components such as unreacted monomers and organic solvents, and then set to a cylinder temperature of 200 ° C. The pelletization of resin was performed using the manufactured extruder, and the copolymer B-1 was created.
The obtained resin had a glass transition temperature of 47 ° C., a number average molecular weight of about 60,000, and a volatile content of 0.19% by weight.

Copolymer B-2: A monomer mixture consisting of 25 parts by weight of butadiene, 15 parts by weight of methyl methacrylate, 60 parts by weight of styrene, and 0.1 parts by weight of t-dodecyl mercaptan was polymerized by a known emulsion polymerization method. It was. The obtained latex was stripped (60 ° C., −0.1 Mpa for 8 hours), and then salted out and dehydrated using sulfuric acid to prepare a copolymer B-2.
The obtained resin had a glass transition temperature of 63 ° C., a number average molecular weight of about 40,000, and a volatile content of 0.16% by weight.

Copolymer B-3: Polymerization of a monomer mixture comprising 40 parts by weight of butyl acrylate, 10 parts by weight of acrylonitrile, 50 parts by weight of α-methylstyrene, and 0.1 parts by weight of t-dodecyl mercaptan by a known emulsion polymerization method. Went. The obtained latex was stripped (60 ° C., −0.1 MPa for 8 hours), and then salted out and dehydrated using sulfuric acid to prepare a copolymer B-3.
The obtained resin had a glass transition temperature of 71 ° C., a number average molecular weight of about 40,000, and a volatile content of 0.17% by weight.

Copolymer B-4: A monomer mixture composed of 15 parts by weight of butyl acrylate, 15 parts by weight of acrylonitrile, 70 parts by weight of styrene, and 0.1 parts by weight of t-dodecyl mercaptan was polymerized by a known emulsion polymerization method. . The obtained latex was stripped (60 ° C., −0.1 Mpa for 8 hours), and then salted out and dehydrated using sulfuric acid to prepare a copolymer B-4.
The obtained resin had a glass transition temperature of 78 ° C., a number average molecular weight of about 40,000, and a volatile content of 0.15% by weight.

Copolymer B-5: Polymerization of a monomer mixture comprising 35 parts by weight of butyl acrylate, 60 parts by weight of methyl methacrylate, 5 parts by weight of styrene, and 0.3 parts by weight of t-dodecyl mercaptan by a known emulsion polymerization method. went. The obtained latex was stripped (60 ° C., −0.1 Mpa for 8 hours), and then salted out and dehydrated with sulfuric acid to prepare a copolymer B-5.
The obtained resin had a glass transition temperature of 46 ° C., a number average molecular weight of about 30,000, and a volatile content of 0.16% by weight.

Copolymer Bi: A monomer mixture comprising 20 parts by weight of acrylonitrile, 80 parts by weight of styrene and 0.1 parts by weight of t-dodecyl mercaptan was polymerized by a known emulsion polymerization method. The obtained latex was stripped (60 ° C., −0.1 Mpa for 8 hours), and then salted out and dehydrated using sulfuric acid to prepare a copolymer Bi.
The obtained resin had a glass transition temperature of 114 ° C., a number average molecular weight of about 40,000, and a volatile content of 0.18% by weight.

Copolymer B-ii: A monomer mixture comprising 25 parts by weight of styrene and 75 parts by weight of methyl methacrylate was polymerized by a known emulsion polymerization method. The resulting latex was stripped (60 ° C., −0.1 Mpa for 8 hours), and then salted out and dehydrated using sulfuric acid to obtain a copolymer B-ii.
The obtained resin had a glass transition temperature of 106 ° C., a number average molecular weight of about 40,000, and a volatile content of 0.18% by weight.

Graft copolymer B-iii: Polymerization of a monomer mixture comprising 25 parts by weight of styrene and 75 parts by weight of methyl methacrylate in the presence of 100 parts by weight of polybutadiene latex (solid content 50% by weight) by a known emulsion polymerization method. Was done. After stripping the obtained latex (60 ° C., −0.1 MPa for 8 hours), salting out and dehydration were performed using sulfuric acid to prepare graft polymer B-iii.
The obtained resin had a glass transition temperature of 106 ° C., a number average molecular weight of about 40,000, and a volatile content of 0.1% by weight.

[Examples 1-7, Comparative Examples 1-3]
Based on the composition ratio shown in Table 1, after mixing the polylactic acid resin (A-1) and the copolymers (B-1 to 5, Bi to iii), carbodilite (LA- per 100 parts by weight of the mixture). 1 part Nisshinbo Co., Ltd.) was added, and kneaded together with a twin screw extruder (set temperature 220 ° C.) to obtain various compositions. The pellets thus obtained were pre-dried at 80 ° C., and then 100 μm thick at a cylinder setting temperature of 230 ° C. using a film molding machine (manufactured by Tanabe Plastic Machinery Co., Ltd.) equipped with a Nagase Sangyo Dena filter. The film was made and various tests were conducted. The results are shown in Table 1. Various test conditions are as follows.

Transparency : The total light transmittance was measured using a haze meter (HM-150 Murakami Color Research Laboratory). unit:%
Bending strength test : Using a MIT-D testing machine manufactured by Toyo Seiki Co., Ltd., the number of bendings until breakage was measured. Unit: times
Low whitening property : According to JIS K 7113, the degree of whitening of the sample whose tensile strength was measured was visually evaluated.
○: No whitening ×: Whitening is observed
Defect inspection : The number of defects having a diameter of 100 to 500 μm was measured using a surface defect inspection apparatus (FITS-L manufactured by Ayaha Engineering Co., Ltd.).
Unit: piece / 1m ²

  The film / sheet molded article obtained in the present invention can be used particularly effectively as various packaging or industrial products as a film or sheet having excellent whitening property and good punching property.

Claims (3)

Polylactic acid resin (A) 5 to 95% by weight, butyl (meth) acrylate and / or butadiene 5 to 40% by weight, acrylonitrile, styrene, α-methylstyrene, phenyl methacrylate, methyl methacrylate, maleimide, N-phenylmaleimide, Thermoplastic resin composition comprising 95 to 5% by weight of copolymer (B) obtained by polymerizing a monomer mixture comprising 95 to 60% by weight of at least one monomer selected from N-cyclohexylmaleimide object. The thermoplastic resin composition according to claim 1, wherein a volatile content at 200 ° C contained in the copolymer (B) is less than 0.2% by weight. The film or sheet according to claim 1 or 2, wherein there are less than 20 defects having a diameter of 100 to 500 µm per 1 m ² .