JP2003286401A - Polylactic acid-containing resin composition, molding and film or sheet therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-containing resin composition excellent in flexibility, having transparency and less in bleeding-out, and to provide a molding and a film or sheet comprising the polylactic acid-containing resin composition. <P>SOLUTION: The polylactic acid-containing resin composition comprises (A) polylactic acid and (B) a polymer essentially comprising an unsaturated carboxylic acid alkyl ester unit, where the weight-average molecular weight of the polymer (B) is ≤30,000. The molding comprising the polylactic acid- containing resin composition, and the film or sheet comprising the polylactic acid-containing resin composition are provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polylactic acid-containing resin composition having excellent flexibility, transparency, and less bleed-out, and a molded article made of the same.

[0002]

2. Description of the Related Art Recently, from the viewpoint of global environmental protection,
Attention has been paid to biodegradable polymers that are decomposed in the natural environment by the action of microorganisms existing in water, and various biodegradable polymers have been developed. Among these, as a biodegradable polymer that can be melt-molded, for example, polyethylene succinate composed of an aliphatic dicarboxylic acid component such as polyhydroxybutyrate, polycaprolactone, succinic acid or adipic acid, and a glycol component such as ethylene glycol or butanediol. Nate, polybutylene adipate, and polylactic acid are known.

Polylactic acid has a relatively low cost, a melting point of about 170 ° C. and heat resistance, and is expected as a melt-degradable biodegradable polymer. Further, recently, lactic acid, which is a monomer, has come to be produced at a low cost by a fermentation method using a microorganism, and since it has become possible to produce polylactic acid at a lower cost, not only as a biodegradable polymer, Utilization as a general-purpose polymer has also been investigated.

However, polylactic acid has the property of being highly rigid and brittle, and thus has a problem that it is difficult to use it in applications requiring flexibility.

As a method for solving this problem, a method of adding a plasticizer has been studied, but when this method is applied to polylactic acid, a so-called bleed-out phenomenon occurs in which the plasticizer is deposited on the surface. And the transparency of polylactic acid is impaired.

[0006] As another method, a method of mixing a polymer having a low glass transition temperature has been studied. However, when this method is applied to polylactic acid, the flexibility is insufficient or the polylactic acid There were problems such as loss of transparency and occurrence of a bleed-out phenomenon.

On the other hand, Polymer, 39 (26), 6
891 (1998) describes that the glass transition temperature of the mixture is lowered by mixing it with polymethyl acrylate having a glass transition temperature lower than that of polylactic acid and having a molecular weight of about 40,000. However, in this method, although the transparency of polylactic acid is not impaired, the glass transition temperature of polymethyl acrylate used is not so low, and therefore the effect of imparting flexibility is insufficient.

[0008] As described above, no method has been found so far which can soften polylactic acid and can suppress the bleed-out phenomenon without impairing the transparency of polylactic acid.

[0009]

The present invention has been achieved as a result of studying the solution of the above-mentioned problems in the prior art, and the object thereof is to achieve the following.
It is an object of the present invention to provide a polylactic acid-containing resin composition having excellent flexibility, transparency, and less bleed-out, and a molded article made of the same.

[0010]

That is, the present invention is
(1) A polymer containing (A) polylactic acid and (B) an unsaturated carboxylic acid alkyl ester-based unit as a main component is contained, and the weight average molecular weight of (B) is 30,000 or less. (2) The polylactic acid-containing resin composition according to (1) above, wherein the weight average molecular weight of (B) is 5000 or less and 300 or more. The glass transition temperature of (B) is 1
The polylactic acid-containing resin composition according to any one of the above (1) to (2), which is 0 ° C. or lower, (4) the (B) further contains a glycidyl group-containing vinyl-based unit and unsaturated. (1) above, which contains at least one selected from dicarboxylic acid anhydride units
The polylactic acid-containing resin composition according to any one of (3),
(5) The polylactic acid-containing resin composition according to any one of (1) to (4) above, wherein the unsaturated carboxylic acid alkyl ester-based unit of (B) is an acrylic acid ester unit, (6) A molded article comprising the polylactic acid-containing resin composition according to any one of (1) to (5) above, and (7) any one of (1) to (5) above. A film or sheet comprising the polylactic acid-containing resin composition described above.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polylactic acid (A) of the present invention is a polymer obtained by polymerizing L-lactic acid and / or D-lactic acid as a main component, but is preferably within the range not impairing the object of the present invention. Is 20 mol% or less, particularly preferably 10 mol% or less, and a copolymerization component other than lactic acid may be copolymerized.

Examples of such other copolymerization component include:
Examples thereof include polyhydric carboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, and lactones. Specifically, oxalic acid,
Malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-
Polyvalent carboxylic acids such as sodium sulfoisophthalic acid and 5-tetrabutylphosphonium sulfoisophthalic acid,
Ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4
-Cyclohexane dimethanol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, bisphenol A, aromatic polyhydric alcohol obtained by addition reaction of ethylene oxide with bisphenol,
Polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, hydroxybenzoic acid Hydroxycarboxylic acids such as acids, glycolide, ε-caprolactone glycolide, ε-
Lactones such as caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone and δ-valerolactone can be used.

In order to obtain high heat resistance with (A) polylactic acid, it is preferable that the lactic acid component has a high optical purity, and it is preferable that 80 mol% or more of L-form or D-form is contained in the total lactic acid component. Further, it is preferably contained at 90 mol% or more, and particularly preferably contained at 95 mol% or more.

As the method for producing (A) polylactic acid, known polymerization methods such as a direct polymerization method from lactic acid and a ring-opening polymerization method via lactide can be used.

(A) The molecular weight and molecular weight distribution of polylactic acid are
The weight average molecular weight is preferably 10,000 or more, more preferably 40,000 or more, and particularly preferably 80,000 or more, as long as it can be substantially molded and processed. . The weight average molecular weight as referred to herein is a weight average molecular weight in terms of polymethylmethacrylate measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

The melting point of (A) polylactic acid is not particularly limited, but is preferably 120 ° C. or higher,
Further, it is preferably 150 ° C. or higher. The melting point can be measured by a differential scanning calorimeter (DSC).

The polymer (B) used in the present invention is a polymer containing an unsaturated carboxylic acid alkyl ester type unit as a main component. If the unsaturated carboxylic acid alkyl ester-based unit in the polymer (B) is the main component,
It may be a homopolymer or a copolymer, and examples of the copolymer include a random copolymer, a block copolymer and a graft copolymer. Here, the main component is a component that accounts for 50 mol% or more, preferably 70 mol% or more, and more preferably 90 mol% with respect to all monomers.
It is a component that accounts for more than mol%. Further, (B) the polymer having an unsaturated carboxylic acid alkyl ester-based unit as a main component may be used alone or in combination of two or more kinds.

In the polymer (B), the raw material monomer for forming the unsaturated carboxylic acid alkyl ester type unit is not particularly limited, but the alkyl moiety in the alkyl ester is an alkyl group having 1 to 6 carbon atoms. Acrylic acid ester and / or methacrylic acid ester having a group or a substituted alkyl group is preferable, and in view of the large effect of improving flexibility,
Acrylic acid esters are more preferred.

Examples of the raw material monomers for forming the unsaturated carboxylic acid alkyl ester type unit include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth).
Acrylic acid-n-propyl, (meth) acrylic acid-n-
Butyl, (meth) acrylic acid-t-butyl, (meth) acrylic acid-n-hexyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid cyclohexyl,
Chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid-2,3, 4,5,6-pentahydroxyhexyl or (meth) acrylic acid-2,
3,4,5-tetrahydroxypentyl and the like can be mentioned. Among them, from the viewpoint of having a great effect of improving flexibility, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid -N-propyl, (meth) acrylic acid-n-butyl, (meth) acrylic acid-t-butyl, (meth) acrylic acid-n-hexyl, and (meth) acrylic acid-2-ethylhexyl are preferable, and further Methyl acrylate or ethyl acrylate is more preferable, and ethyl acrylate is particularly preferable.
These may be used alone or in combination of two or more.

Further, in the polymer (B) containing an unsaturated carboxylic acid alkyl ester type unit as a main component, a polymer further containing other units can be used, if necessary. Glycidyl group-containing vinyl unit, unsaturated dicarboxylic acid anhydride unit, aliphatic vinyl unit, aromatic vinyl unit, vinyl cyanide unit, maleimide unit, unsaturated dicarboxylic acid unit or other vinyl unit It may also contain,
These units may be used alone or in combination of two or more. Among these, those containing at least one selected from a glycidyl group-containing vinyl unit and an unsaturated dicarboxylic acid anhydride unit are particularly preferable from the viewpoint of having a great effect of improving flexibility.

The raw material monomer forming the glycidyl group-containing vinyl unit is not particularly limited,
Examples thereof include glycidyl (meth) acrylate, glycidyl itaconate, diglycidyl itaconate, allyl glycidyl ether, styrene-4-glycidyl ether, and 4-glycidyl styrene. Among them, glycidyl (meth) acrylate is preferably used. These may be used alone or in combination of two or more.

Examples of the raw material monomer forming the unsaturated dicarboxylic acid anhydride unit include maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, and the like. Among them, maleic anhydride is preferred. used. These may be used alone or in combination of two or more.

The raw material monomer forming the aliphatic vinyl-based unit is ethylene, propylene or butadiene, and the aromatic vinyl-based unit is styrene or α.
-Methylstyrene, 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, halogenated styrene, etc. The raw material monomer forming the vinyl cyanide unit is acrylonitrile, methacrylonitrile or ethacrylonitrile, and the raw material monomer forming the maleimide unit is maleimide, N-methylmaleimide, N-ethylmaleimide, N.
-Propylmaleimide, N-isopropylmaleimide,
N-cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide or N-
As a raw material monomer forming an unsaturated dicarboxylic acid-based unit such as (chlorophenyl) maleimide, maleic acid,
As raw material monomers for forming other vinyl units such as maleic acid monoethyl ester, itaconic acid and phthalic acid, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N
-Propylmethacrylamide, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acroyl-oxazoline or 2-styryl-oxazoline and the like can be mentioned, and these can be used alone or in combination of two or more.

The polymer (B) having an unsaturated carboxylic acid alkyl ester type unit as the main component of the present invention is required to have a weight average molecular weight of 30,000 or less. When the weight average molecular weight exceeds 30,000, flexibility, transparency and suppression of bleed-out phenomenon cannot all be satisfied. Also,
The weight average molecular weight is preferably 20,000 or less, more preferably 10,000 or less, and further 500 in terms of higher flexibility, transparency and suppression of bleed-out phenomenon.
It is more preferably 0 or less, and most preferably 3000 or less. Although the lower limit is not particularly limited, it is preferably 200 or more, and more preferably 300 or more. If it is less than 200, the bleed-out phenomenon tends to increase.

Generally, when another polymer or plasticizer having a weight average molecular weight range defined in the present invention is blended with polylactic acid, a remarkable bleed-out phenomenon is usually accompanied, but surprisingly. The bleed-out phenomenon is remarkably suppressed when the polymer containing the unsaturated carboxylic acid alkyl ester type unit as the main component of the present invention (B) is used.

The molecular weight distribution of the ratio (weight average molecular weight / number average molecular weight) of the weight average molecular weight to the number average molecular weight of the polymer (B) having an unsaturated carboxylic acid alkyl ester type unit as a main component in the present invention is as follows: Although not particularly limited, it is preferably 3 or less, more preferably 2 or less, further preferably 1.8 or less, and most preferably 1.6 or less.

The weight average molecular weight and number average molecular weight described above are polystyrene equivalent weight average molecular weights measured by gel permeation chromatography (GPC) using chloroform as a solvent.

The glass transition temperature of the polymer containing the unsaturated carboxylic acid alkyl ester type unit as the main component (B) in the present invention is not particularly limited, but it gives flexibility to the polylactic acid-containing resin composition. From the perspective of doing 10
C. or less is preferable, 5 ° C. or less is more preferable, 0 ° C. or less is more preferable, and −1 is particularly preferable.
Most preferably, the temperature is 0 ° C or lower. The method for measuring the glass transition temperature is not particularly limited, and any of the method of measuring with a differential scanning calorimeter (DSC) and the method of measuring with a dynamic viscoelasticity test can be used.

The polymer (B) containing an unsaturated carboxylic acid alkyl ester type unit as a main component in the present invention usually contains a volatile component because unreacted raw material monomers and solvents remain. The amount of the non-volatile component that is the balance is not particularly limited, but the amount of the non-volatile component is preferably large from the viewpoint of suppressing the generation of gas. Specifically, it is preferably 95% by weight or more, more preferably 97% by weight or more, further preferably 98% by weight or more, and particularly preferably 98.5% by weight or more. preferable. In addition, the non-volatile component mentioned here represents a residual amount ratio when 10 g of the sample is heated at 110 ° C. for 1 hour in a nitrogen atmosphere.

In the polymer (B) having an unsaturated carboxylic acid alkyl ester type unit as a main component in the present invention, a sulfur compound may be used as a chain transfer agent (molecular weight adjusting agent) in order to obtain a low molecular weight product. However, in that case the polymer usually contains sulfur. The sulfur content of the polymer having an unsaturated carboxylic acid alkyl ester-based unit (B) as a main component used in the present invention is not particularly limited, but from the viewpoint of suppressing an unpleasant odor, the sulfur content is The smaller the amount, the better. Specifically, 1000 as a sulfur atom
ppm or less is preferable, 100 ppm or less is more preferable, 10 ppm or less is more preferable, and 1 ppm is particularly preferable.
Most preferably it is:

The method for producing the polymer (B) containing an unsaturated carboxylic acid alkyl ester type unit as a main component in the present invention is not particularly limited, and bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization are carried out. Known polymerization methods such as can be used. When these methods are used, a polymerization initiator, a chain transfer agent, a solvent and the like may be used, but these are mainly composed of the finally obtained (B) unsaturated carboxylic acid alkyl ester type unit. It may remain as an impurity in the polymer. Although the amount of these impurities is not particularly limited, it is preferable that the amount of impurities is small from the viewpoint of suppressing deterioration of heat resistance and weather resistance. Specifically, the amount of impurities is preferably 10% by weight or less, more preferably 5% by weight or less, further preferably 3% by weight or less, and particularly preferably 1% by weight or less with respect to the finally obtained (B) polymer. Most preferably.

[B] Polymer having an unsaturated carboxylic acid alkyl ester-based unit as a main component which satisfies the above-mentioned molecular weight, molecular weight distribution, glass transition temperature, non-volatile component content, sulfur content, impurity content, etc. As a manufacturing method, 15
At a high temperature of 0 ° C or higher and under pressure conditions (preferably 1 MPa
In the above), the method of continuous bulk polymerization in a short time (preferably 5 to 30 minutes) has a high polymerization rate and does not use a polymerization initiator, a chain transfer agent or a solvent which causes impurities or sulfur content. To more preferred.

The weight ratio of the (A) polylactic acid to the (B) polymer having an unsaturated carboxylic acid alkyl ester type unit as a main component in the present invention is not particularly limited,
(A) 100 parts by weight of polylactic acid, (B) 100 parts by weight or less of a polymer containing an unsaturated carboxylic acid alkyl ester-based unit as a main component, more preferably 50 parts by weight or less, and particularly preferably 30 parts by weight or less. Most preferred. Although the lower limit is not particularly limited, it is preferably 1 part by weight or more, more preferably 5 parts by weight or more, and particularly preferably 10 parts by weight or more.

The polylactic acid-containing resin composition of the present invention is
It is composed of a polymer containing (A) polylactic acid and (B) an unsaturated carboxylic acid alkyl ester-based unit as a main component, but in a preferred embodiment, it is a compatible blend. As used herein, "compatibility" is used to describe a mixture of polymers that forms a homogeneous phase in the amorphous phase at the molecular level. When one or both of the formulations form both crystalline and amorphous phases, compatible means that the amorphous phases are mixed at the molecular level.

The determination of compatibility in a formulation can be done in several ways.

The most general method for judging compatibility is the glass transition temperature. In compatible formulations, the glass transition temperature varies from that of each alone and often exhibits a single glass transition temperature. This method can also be used in the present invention, and the polylactic acid-containing resin composition of the present invention preferably exhibits a temperature lower than the glass transition temperature of polylactic acid alone.

The polylactic acid-containing resin composition of the present invention contains a conventional additive such as a filler (talc, clay, mica, sericite, zeolite, bentonite, montmorillonite, etc.) as long as the object of the present invention is not impaired. Synthetic mica, dolomite, kaolin, fine silicic acid, feldspar powder, potassium titanate, shirasu balloon, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, calcium phosphate, magnesium phosphate, calcium oxide, aluminum oxide, titanium oxide, silicic acid Aluminum, silicon oxide, gypsum, glass fiber, carbon fiber, metal fiber, natural fiber, organic fiber, glass flake, glass beads, ceramic fiber, ceramic beads, asbestos, wollastonite, novaculite, dawsonite or clay), ultraviolet Absorber (resorcinol, salicylate, benzotriazole, benzophenone, etc.), heat stabilizer (hindered phenol, hydroquinone, phosphites and their substituted derivatives, etc.), lubricants, release agent (montanic acid and its salts, its esters,
Its half-esters, stearyl alcohol, stearamide and polyethylene wax, etc.), dyes (such as nigrosine) and colorants, including pigments (cadmium sulfide, phthalocyanine, etc.), anti-colorants (phosphites, hypophosphites, etc.), Flame retardant (red phosphorus, phosphoric acid ester, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, magnesium hydroxide, melamine and cyanuric acid or its salt, etc.), conductive agent or colorant (carbon black, etc.), slidability One or more of improving agents (graphite, fluororesin, etc.), crystal nucleating agents (talc, organic carboxylic acid metal salts, etc.), antistatic agents, etc. can be added.

In the polylactic acid-containing resin composition of the present invention, other thermoplastic resins (for example, polyethylene, polypropylene, acrylic resin, polyamide, polyphenylene sulfide resin, etc.) can be used as long as the object of the present invention is not impaired.
Polyetheretherketone resin, polyester, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyetherimide) or thermosetting resin (for example, phenol resin, melamine resin, polyester resin, silicone resin, epoxy resin, etc.)
Alternatively, at least one kind of soft thermoplastic resin (for example, ethylene / glycidyl methacrylate copolymer, polyester elastomer, polyamide elastomer, ethylene / propylene terpolymer, ethylene / butene-1 copolymer, etc.) may be further contained. The method for producing the composition of the present invention that can be carried out is not particularly limited, but for example, (A) polylactic acid, (B) a polymer having an unsaturated carboxylic acid alkyl ester-based unit as a main component, and if necessary, A method in which other additives are pre-blended and then melt-kneaded uniformly with a uniaxial or biaxial extruder at a temperature equal to or higher than the melting point, or a method in which the solvent is mixed and then the solvent is removed is preferably used.

The polylactic acid-containing resin composition of the present invention can be processed into various molded products by a method such as injection molding or extrusion molding and used. As a molded product, a film,
It can be used as a sheet, a fiber, an injection molded product, an extrusion molded product or a blow molded product.

The film or sheet may be unstretched,
Various films or sheets such as uniaxially stretched and biaxially stretched can be used. As the stretching method, a method such as an inflation simultaneous biaxial stretching method, a stenter simultaneous biaxial stretching method or a stenter sequential biaxial stretching method can be used. Among them, in view of film-forming stability and thickness uniformity, a stenter is used. The sequential biaxial stretching method is preferred.

The fibers include undrawn yarn, drawn yarn,
It can be used as various fibers such as super drawn yarn.

Molded articles comprising the polylactic acid-containing resin composition of the present invention are agricultural materials, horticultural materials, fishery materials, civil engineering / construction materials, stationery, medical supplies, automobile parts, electricity / electrical materials.
It can be used for various purposes such as electronic parts and daily necessities.

[0043]

EXAMPLES The constitution and effects of the present invention will be described below in more detail with reference to examples. Here, the number of parts in the examples indicates parts by weight.

(1) Measurement of molecular weight This is the value of the weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC). GPC measurement uses a differential refractometer WATERS410 manufactured by WATERS as a detector and MODEL as a pump.
The column was loaded with S by 510 high performance liquid chromatography.
hodex GPC K-806M and Shodex G
PC K-G was connected in series. The measurement conditions were a flow rate of 0.5 mL / min, chloroform was used as a solvent, and a solution having a sample concentration of 1 mg / mL was 0.1 m.
L was injected.

(2) Glass Transition Temperature (Tg) Each raw material before compounding was measured by a differential scanning calorimeter (Seiko Denshi RDC220). The measurement conditions were as follows: sample 10 mg, under nitrogen atmosphere, heating rate 20 ° C. /
Minutes.

For the polylactic acid-containing resin composition obtained after compounding, tan δ was measured by a dynamic viscoelasticity measuring device (Rheovibron DDV-II-EA manufactured by Toyo Baldwin), and the peak value was taken as the glass transition temperature. The measurement conditions were as follows: After mounting the test piece in the tension mode cell with a chuck distance of 30 mm, the temperature rising rate was 2 ° C / min and the frequency was 3.5 Hz.
Set to. The test piece was molded using a press molding machine.
After pressurizing at 00 ° C. for 5 minutes, it was cooled for 2 minutes using a press molding machine at 30 ° C. to prepare a press film having a thickness of about 0.05 mm, which was cut into a strip of 40 mm × 2 mm to give a test piece.

(3) Judgment was made in three steps based on the flexible tensile modulus. That is, when the tensile modulus is less than 500 MPa (excellent in flexibility)
Is ⊚, the tensile elastic modulus is 500 MPa or more and 1700 MPa
If it is less than (excellent in flexibility), ○, the tensile modulus is 17
When the pressure was 00 MPa or more (inferior in flexibility), the result was x. The tensile modulus was measured using a tensile tester (tensile tester UTA2.5T manufactured by Tensilon) under the conditions of a sample length of 20 mm and a pulling speed of 5 mm / min. The test piece was pressed with a press molding machine at 200 ° C. for 5 minutes and then cooled with a press molding machine at 30 ° C. for 2 minutes, and a press sheet having a thickness of 1 mm was cut out to obtain a test piece.

(4) Transparency It was visually evaluated in three stages. That is, the above (2)
With respect to the press film prepared in (1), the transparency was high (particularly excellent), ∘ when there was some turbidity (excellent), and × when it was cloudy and opaque (poor).

(5) Bleed out The press film produced in (2) above was 30 mm × 20.
After the test piece cut out in a rectangular shape of mm was treated at 140 ° C. for 1 hour, the surface of the test piece was visually and manually touched, and the weight reduction rate before and after the heat treatment was used to judge in three stages. That is, when there is no precipitate on the surface and the weight reduction ratio is less than 1% by weight (especially excellent), ⊚, and when there is some precipitate on the surface and the weight reduction ratio is 1% by weight or more and less than 5% by weight ( (Excellent) was evaluated as ◯, and when there was a precipitate on the surface and the weight reduction ratio was 5% by weight or more (poor), it was evaluated as x.

(6) A non-volatile component was calculated by calculating the residual amount ratio from the residual amount after heating 10 g of the non-volatile component sample at 110 ° C. for 1 hour in a nitrogen atmosphere.

Reference Example 1 Polylactic acid (A-1) (A-1) 50 parts of commercially available L-lactide was uniformly dissolved in a reaction vessel equipped with a stirrer at 120 ° C. under a nitrogen atmosphere, and then, The temperature was brought to 140 ° C. and tin octylate 0.1.
After adding 05 parts, a polymerization reaction was carried out for 1 hour. After the completion of the polymerization reaction, the reaction product was dissolved in chloroform and precipitated in methanol (10 times the amount of chloroform) with stirring to completely remove the monomer, and poly-L-lactic acid (A-
1) was obtained. The obtained Tg of (A-1) was 59 ° C., the melting point was 171 ° C., and the content of D-form was 1.2.
It was mol% and the weight average molecular weight was 160,000.

Reference Example 2 (B) Polymer (B-1) Mainly Containing Unsaturated Carboxylic Acid Alkyl Ester Unit (B-1) Methyl acrylate polymer (weight average molecular weight 1000) manufactured by Soken Chemical Co., Ltd. was used. Tg was -41 ° C, and the nonvolatile component was 98% by weight or more.

(B-2) An ethyl acrylate polymer (weight average molecular weight: 1200) manufactured by Soken Chemical Industry Co., Ltd. was used. Tg
Was -57 ° C, and the nonvolatile component was 97% by weight or more.

(B-3) Using a reaction vessel equipped with a stirrer, a reflux device and a dropping device, 70 parts of methyl acrylate and 30 parts of n-butyl acrylate were used as monomers.
Parts, benzene as a solvent, azobisisobutyronitrile as a polymerization initiator, and n-lauryl mercaptan as a chain transfer agent at 85 ° C. for 1 hour to perform solution polymerization, and after completion of the polymerization reaction, under reduced pressure of 0.13 kPa. At, the solvent and residual monomers are removed, and the acrylic polymer (B
-3) was obtained. The Tg of the obtained (B-3) was -61 ° C.
And the weight average molecular weight was 1,300. The nonvolatile content was 97% by weight or more.

(B-4) Using a reaction vessel equipped with a stirrer, a reflux device and a dropping device, 94 parts of ethyl acrylate and 6 parts of glycidyl methacrylate were used as monomers.
Benzene as a solvent, azobisisobutyronitrile as a polymerization initiator and n-lauryl mercaptan as a chain transfer agent were used to carry out solution polymerization at 80 ° C. for 1 hour, and after completion of the polymerization reaction, under reduced pressure of 0.13 kPa, The solvent and the residual monomer were removed to obtain an acrylic polymer (B-4). The Tg of the obtained (B-4) was -35 ° C,
The weight average molecular weight was 3000. The nonvolatile content was 97% by weight or more.

(B-5) Using a reaction vessel equipped with a stirrer and a dropping device, a mixed monomer of 94 parts of ethyl acrylate and 6 parts of glycidyl methacrylate was used as a monomer, and di-t-butyl peroxide was used as a polymerization initiator. While continuously feeding the mixture of 250 ° C and 2.5MP
Polymerization was carried out under the condition of a with a residence time of 15 minutes. 0.13 kP after continuously removing the polymer from the reaction vessel
The residual monomer was removed under reduced pressure of a to obtain an acrylic polymer (B-5). The obtained Tg of (B-5) was
It was -39 degreeC and the weight average molecular weight was 2200.
Further, the non-volatile component was 99% by weight or more. There was no sulfur odor because no sulfur compound (chain transfer agent) was used.

(B-6) Using a reaction vessel equipped with a stirrer, a reflux device and a dropping device, 100 parts of methyl acrylate as a monomer, benzene as a solvent, azobisisobutyronitrile as a polymerization initiator and chain transfer. Using n-lauryl mercaptan as an agent, solution polymerization was performed at 85 ° C. for 1 hour, and after completion of the polymerization reaction, the solvent and the residual monomer were removed under a reduced pressure of 0.13 kPa to obtain an acrylic polymer (B-6 ) Got. The weight average molecular weight of the obtained (B-6) was 250. The nonvolatile component is 9
It was 6% by weight or more. The Tg could not be observed.

(B-7) Using a reaction vessel equipped with a stirrer, a reflux device and a dropping device, 100 parts of methyl acrylate as a monomer, benzene as a solvent, azobisisobutyronitrile as a polymerization initiator and chain transfer. Solution polymerization was performed using n-lauryl mercaptan as an agent at 80 ° C. for 1 hour, and after completion of the polymerization reaction, the solvent and the residual monomer were removed under a reduced pressure of 0.13 kPa to obtain an acrylic polymer (B-7). Got The obtained Tg of (B-7)
Was 3 ° C. and the weight average molecular weight was 7,900.
The nonvolatile content was 96% by weight or more.

(B-8) Using a reaction vessel equipped with a stirrer, a reflux device and a dropping device, 70 parts of methyl acrylate and 30 parts of n-butyl acrylate were used as monomers.
Parts, benzene as a solvent, azobisisobutyronitrile as a polymerization initiator, and n-lauryl mercaptan as a chain transfer agent at 80 ° C. for 1 hour for solution polymerization,
After completion of the polymerization reaction, the solvent and the residual monomer were removed under a reduced pressure of 0.13 kPa to give an acrylic polymer (B-
8) was obtained. The Tg of the obtained (B-8) was -12 ° C, and the weight average molecular weight was 21,000. The nonvolatile content was 97% by weight or more. [Reference Example 3] (C) Plasticizer and acrylic polymer (C-1) Plasticizer triacetin (molecular weight 218) manufactured by Daihachi Chemical Industry Co., Ltd. was used. Tg could not be observed.

(C-2) Polyethylene glycol 2000 (weight average molecular weight 2000) manufactured by Wako Pure Chemical Industries, Ltd. was used. Tg was -64 ° C.

(C-3) Adipic acid plasticizer PN-400 (weight average molecular weight 2000) manufactured by Asahi Denka Co., Ltd. was used.
Tg was -6 ° C.

(C-4) Polymethyl acrylate (weight average molecular weight 37,000) manufactured by Aldrich was used. Tg
Was 11 ° C.

(C-5) Polyethyl acrylate (weight average molecular weight 95,000) manufactured by Aldrich was used. Tg
Was -15 ° C. (C-6) polybutyl acrylate manufactured by Aldrich (weight average molecular weight of 99,000) was used. Tg was -48 ° C.

(C-7) 2-Ethylhexyl polyacrylate (weight average molecular weight 92,000) manufactured by Aldrich was used. Tg was -55 ° C.

(C-8) Using a reaction vessel equipped with a stirrer, a reflux device and a dropping device, 70 parts of methyl acrylate and 30 parts of -n-butyl acrylate were used as monomers.
Parts, benzene as a solvent, azobisisobutyronitrile as a polymerization initiator, and n-lauryl mercaptan as a chain transfer agent at 80 ° C. for 1.5 hours to carry out solution polymerization, and after completion of the polymerization reaction, 0.13 kPa Under reduced pressure,
The solvent and the residual monomer were removed to obtain an acrylic polymer (C-8). The Tg of the obtained (C-8) was -1.
It was 0 degreeC and the weight average molecular weight was 38,000. The nonvolatile content was 97% or more.

[Examples 1 to 9 and Comparative Examples 1 to 9] According to the composition shown in Table 1, a twin screw extruder was used and the temperature was 210 ° C.
Was melt-extruded to obtain a pelletized polylactic acid-containing resin composition. The obtained pellets were formed into a film or sheet with a press molding machine, and test pieces were cut out and evaluated.

The evaluation results of each test piece are shown in Table 1.

[0068]

[Table 1]

The following are clear from the examples and comparative examples in Table 1. From the comparison between Examples 1 to 9 and Comparative Examples 1 to 9, a single glass was obtained by mixing a polymer containing an unsaturated carboxylic acid alkyl ester-based unit having a weight average molecular weight of 30,000 or less as a main component. It can be seen that a compatible compound having a transition temperature was obtained, and the compatible compound was a material having excellent flexibility and transparency and having little bleed out. Furthermore, in Examples 1 to 6, materials having remarkably excellent flexibility and transparency, an extremely small rate of weight loss due to heating and a particularly small amount of bleed-out were obtained. In Comparative Examples 2 to 4 in which a low molecular weight plasticizer was mixed, a compatible blend was obtained, but the bleed-out phenomenon was remarkable, and a comparative example in which a poly (methyl acrylate) having a weight average molecular weight of 37,000 was mixed. In No. 5, although a compatible composition was obtained, the flexibility was insufficient. Further, in Comparative Examples 6 to 9 in which a polymer having an unsaturated carboxylic acid alkyl ester-based unit as a main component having a weight average molecular weight of more than 30,000 was mixed, 2
Since the glass transition temperature at the point was observed, it was found that a compatible compound could not be obtained, and the flexibility and transparency were poor, and only a remarkable bleed-out phenomenon was obtained.

[0070]

According to the present invention, it is possible to provide a polylactic acid-containing resin composition having excellent flexibility, transparency, and less bleed-out. Further, the polylactic acid-containing resin composition of the present invention can be used as various molded products, particularly films and the like.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA33 AA43 AF26 AF30 AF52                       AH01 AH03 AH04 AH07 AH12                       BB05 BB06 BC01                 4J002 BG03X CF18W GA00 GB00                       GC00 GL00 GN00 GQ00                 4J200 AA04 AA06 BA14 CA01 DA01                       DA07 DA12 DA16 DA22 DA24                       DA28 EA09 EA21 EA22

Claims (7)

[Claims] 1. A polymer containing (A) polylactic acid and (B) a polymer having an unsaturated carboxylic acid alkyl ester type unit as a main component, and (B) having a weight average molecular weight of 30,000 or less. A polylactic acid-containing resin composition comprising: 2. The polylactic acid-containing resin composition according to claim 1, wherein the weight average molecular weight of (B) is 5000 or less and 300 or more. 3. The polylactic acid-containing resin composition according to claim 1, wherein the glass transition temperature of (B) is 10 ° C. or lower. 4. The method according to claim 1, wherein the (B) further contains at least one selected from a glycidyl group-containing vinyl unit and an unsaturated dicarboxylic acid anhydride unit. The polylactic acid-containing resin composition described. 5. The polylactic acid-containing resin composition according to any one of claims 1 to 4, wherein the unsaturated carboxylic acid alkyl ester-based unit (B) is an acrylic acid ester unit. 6. A molded article comprising the polylactic acid-containing resin composition according to any one of claims 1 to 5. 7. A film or sheet comprising the polylactic acid-containing resin composition according to any one of claims 1 to 5.