JP2000248163A - Composition of lactic acid series having graft chain and its molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition of lactic acid series having a graft chain for having transparency, flexibility, an aging stability, and excellent moldability by comprising a lactic acid component of not less than a specific amount, and graft polymerizing a plasticizer of a weight-average molecular weight and solubility parameter(SP) with specific values thereof to a lactic acid series polymer having not less than a specific value of a weight-average molecular weight. SOLUTION: A composition of lactic acid series having a graft chain comprises a lactic component of at least 50% based on the weight fraction and is obtained by graft polymerizing a plasticizer having a weight-average molecular weight of 100-5,000 and a solubility parameter(SP) value of 9.0-11.0 to a lactic acid series polymer having a weight-average molecular weight of at least 10,000. The composition is obtained by melt mixing and polymerizing the lactic acid series polymer and the plasticizer at a temperature of 100-180 deg.C. An additional amount of the plasticizer is preferably 5-500 pts.wt. per 100 pts.wt. of the lactic acid series polymer. To be more specific, the plasticizer is preferably dimethyl phthalate, diethyl phthalate, ethyl phthalyl ethyl glycolate, triethylene glycol diacetate, an ether ester, tributyl acetylcitrate or triacetin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lactic acid composition characterized by having a plastic component in a graft group. This biodegradable polylactic acid-based polymer is used for packaging materials, industrial materials,
Although it can be used for various uses such as industrial supplies and containers, it is particularly suitable as a material for films, tapes and sheets requiring flexibility and transparency. In addition, it has stability over time because of the structure containing a plasticizer in the graft chain. Further, since it has a branched structure, the rubber-like elastic region is wide and has excellent shock absorbing properties, and is suitable for use as a shock absorbing material, a vibration damping material and a vibration damping material.
Furthermore, since it has biodegradability, the problem of waste disposal like conventional plastics is reduced.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of protection of the natural environment, biodegradable polymers that can be decomposed in the natural environment and molded products thereof have been demanded, and studies on naturally degradable resins such as aliphatic polyesters have been actively conducted. . In particular, the lactic acid-based polymer has a glass transition point of 60 ° C and a melting point of 170 to 180 ° C, and has high thermal stability and excellent transparency.・ It is expected to spread. Of these, the development of alternatives to soft vinyl chloride materials, which are likely to generate dioxins, is desired, but lactic acid-based polymers have high crystallinity and their rigid molecular structure makes it difficult to realize flexible physical properties. Met.
At the present time, there is no transparent and flexible material for other biodegradable polymers.

JP-A-8-199052 and JP-A-8-199052
JP-A-199053 and JP-A-8-283557 disclose compositions containing a (poly) ester plasticizer using an ether bond-containing glycol such as polyethylene glycol. And high stability with time. In addition, there was a problem in the melting characteristics in forming a film or the like. US Patent 5180
No. 765 discloses a composition in which a low molecular weight product of lactic acid or lactide which is a raw material of a lactic acid polymer is added as a plasticizer as a plasticizer. However, there is a problem in stability over time because the temperature is reduced and decomposition is promoted.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lactic acid-based copolymer composition having transparency and controllable plasticity and having stability over time. .

[0005]

Means for Solving the Problems In order to solve such problems, the present inventors have made intensive studies and have found a composition which has stability over time, is transparent and can control plasticity. That is, an object of the present invention is to provide a composition having transparency and flexibility, stability over time, and excellent moldability by graft-polymerizing a plastic component to a lactic acid-based polymer.
In the present invention, the lactic acid-based polymer (A) and the plasticizer (B)
The present invention relates to a lactic acid-based graft copolymer composition that is melt-mixed at 0 to 180 ° C and polymerized. Furthermore, the present invention relates to a molded article of the composition obtained by the present invention.

Hereinafter, the lactic acid-based polymer (A) and the plasticizer (B) used in the present invention will be described in order. The lactic acid-based polymer (A) in the present invention includes a lactic acid homopolymer, a lactic acid copolymer, and a blend polymer. Examples of the lactic acid homopolymer include L-lactide comprising two L-lactic acids, D-lactide comprising D-lactic acid, and meso-lactide comprising L-lactic acid and D-lactic acid. The polymer used as a main raw material may be used, and is obtained by performing a polymerization reaction in the presence of a catalyst. L-lactide or D-
The copolymer containing only lactide can be crystallized to obtain a high melting point copolymer. In the copolymer of the present invention, even better properties can be obtained by combining these three lactides. A lactic acid copolymer is a lactic acid monomer or lactide copolymerized with another copolymerizable component. Examples of such other components include dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, and lactones having two or more ester bond-forming functional groups, and various polyesters and polyethers composed of these various components. And various polycarbonates.

The dicarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid and the like. Examples of polyhydric alcohols include aromatic polyhydric alcohols such as those obtained by adding ethylene oxide to bisphenol, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylolpropane, neomethyl Aliphatic polyhydric alcohols such as pentyl glycol, diethylene glycol,
Examples include ether glycols such as triethylene glycol, polyethylene glycol, and polypropylene glycol. Examples of hydroxycarboxylic acids include glycolic acid, hydroxybutylcarboxylic acid, and others described in
And those described in US Pat. Examples of the lactone include glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, and δ-valerolactone.

[0008] The lactic acid-based polymer is synthesized by a conventionally known method. That is, direct dehydration condensation from a lactic acid monomer as described in JP-A-7-33861, JP-A-59-96123, and Proceedings of the Society of Polymer Discussion, Vol. 44, pp. 3198-3199, or lactic acid cyclic dimer It can be synthesized by ring-opening polymerization of lactide. When performing direct dehydration condensation, L-lactic acid, D-lactic acid, DL-lactic acid,
Alternatively, lactic acid of any of these mixtures may be used.
Also, when performing ring-opening polymerization, L-lactide, D-lactide,
-Lactide, DL-lactide or any mixture of these may be used.

If the lactic acid component is less than 50% by weight in the lactic acid-based polymer, it is not preferable because the unique properties of polylactic acid such as transparency, heat resistance and biodegradability are lost. Further, when the weight average molecular weight is 10,000 or less, it is not preferable because sufficient adhesive strength and elastic modulus are impaired especially for use in adhesives and adhesives.

Lactide synthesis, purification and polymerization procedures are described, for example, in US Pat. No. 4,057,537, published European Patent Application No. 261572, Polymer Bulletin, 14, 49.
1-495 (1985) and Makromol Chem., 187, 1611-16
28 (1986). The catalyst used for this polymerization reaction is not particularly limited, but a known lactic acid polymerization catalyst can be used. For example, tin compounds such as tin tin lactate, tin tartrate, tin dicaprylate, tin dilaurate, tin dipalmitate, tin distearate, tin dioleate, tin α-naphthoate, tin β-naphthoate, and tin octylate , Powdered tin, tin oxide; zinc dust, zinc halide, zinc oxide,
Organic zinc compounds, titanium compounds such as tetrapropyl titanate, zirconium compounds such as zirconium isopropoxide, antimony compounds such as antimony trioxide, bismuth compounds such as bismuth (III) oxide, aluminum oxide, and aluminum isopropoxy And aluminum-based compounds such as aluminum. Among them, a catalyst composed of tin or a tin compound is particularly preferable from the viewpoint of activity. The amount of these catalysts used is, for example, in the case of performing ring-opening polymerization, 0.001 to 5% by weight based on lactide.
It is about. The polymerization reaction can be usually carried out at a temperature of 100 to 220 ° C in the presence of the above catalyst, depending on the type of the catalyst. It is also preferable to carry out two-stage polymerization as described in JP-A-7-247345.

As the plasticizer (B) used in the present invention, a plasticizer generally used for plasticizing polylactic acid or a modified product of polylactic acid can be used. Examples of such plasticizers include many plasticizers that are widely developed for vinyl chloride polymers, but preferably include phthalates,
Adipic acid ester, glycolic acid derivative, ether ester derivative, glycerin derivative, alkyl phosphate ester, dialkylater, diester, tricarboxylate ester, polyester, polyglycol diester, alkyl alkylate diester, aliphatic diester,
A single or a plurality of mixtures selected from alkylator monoesters, citrates, and aromatic hydrocarbons can be used. More specifically, the plasticizer (B) is a single or a plurality of plasticizers selected from dimethyl phthalate, diethyl phthalate, ethyl phthalyl ethyl glycolate, triethylene glycol diacetate, ether ester, tributyl acetyl citrate, and triacetin. Mixtures are preferred.

Regarding the solubility parameter (SP) value,
Generally, it is known that those having close SP values have high compatibility. Since the lactic acid-based polymer has an SP value of about 9.7,
A plasticizer having a P value of 9.0 to 11.0 is preferred. More preferably, it is 9.5 to 10.5. In particular, a higher SP value than a lactic acid-based polymer tends to have higher compatibility than a lower lactic acid-based polymer. If it is smaller than 9.0 or larger than 11.0, the compatibility is poor and the transparency is reduced.

The weight average molecular weight of the plasticizer (B) is from 100 to
5000 is preferable, and 200-3000 is more preferable.
Is good. When the weight average molecular weight is less than 100, a sufficient plasticizing effect cannot be obtained, and when it is more than 5,000, a sufficient plasticizing effect cannot be obtained, and the molecular properties of the plasticizer become remarkable, and heat resistance and transparency are reduced. Is not preferred.
The blending amount of the plasticizer (B) is 100 parts of the lactic acid-based polymer (A).
5 to 500 parts by weight, preferably 20 to 1 part by weight per part by weight
00 parts by weight. If the amount of the plasticizer is less than 5 parts by weight, the softening temperature of the lactic acid-based polymer cannot be sufficiently lowered, and if the amount is more than 100 parts by weight, the efficiency of the copolymerization reaction decreases. Specifically, for example, as a compounding example effective for plasticizing a lactic acid-based polymer, lactic acid-based polymer 100
10 to 100 parts by weight of dimethyl phthalate based on parts by weight,
And / or 10 to 100 parts by weight of diethyl phthalate can be used. Alternatively, similarly, RS1000 manufactured by Asahi Denka Kogyo KK may be used as triacetin and / or triethylene glycol diacetate and ether ester. By using these plasticizers (B), it is possible to lower the softening temperature of the lactic acid-based polymer while maintaining the transparency and hue. As a result, the color of the copolymer can be kept good, and a sufficient plastic effect can be imparted to the molded article.

The weight average molecular weight of the lactic acid-based polymer is 10,000 or more, preferably 50,000 to 30.
It is 0000.

Next, the manufacturing method will be described in order. The lactic acid-based polymer (A) and the plasticizer (B) are melt-mixed in advance. The method of plasticizing the lactic acid-based polymer (A) with the plasticizer (B) is as follows.
Known methods can be used. For example, 10 to 50 parts by weight of dimethyl phthalate and 10 to 50 parts by weight of diethyl phthalate are added to 100 parts by weight of the lactic acid-based polymer (A),
It is obtained by extruding at 0 ° C. and stirring and melting under a nitrogen atmosphere. When the lactic acid-based polymer (A) and the plasticizer (B) are melt-mixed in advance, the lactic acid-based polymer (A) and the plasticizer (B) are preferably mixed at a temperature of, for example, 180 ° C. in a dry nitrogen stream in order to prevent water from being mixed. The temperature for melt-mixing is preferably equal to or higher than the melting temperature of the lactic acid-based polymer (A). If the melting temperature is too high, the plasticizer (B) is volatilized and reduced, and the physical properties of the composition become insufficient. Is preferably performed in the range of 80 to 180 ° C. Next, free radicals are generated in the obtained mixture, and a grafting reaction is performed. As a method for generating free radicals, a known method such as a method of adding a radical initiator such as a peroxide or a method of irradiating an electron beam with a wavelength of 400 nm or less and an intensity of 120 mW / cm ² or more can be used. For example, 0.1 to 10 parts by weight of peroxide is
The reaction is performed by adding parts by weight.

Furthermore, when the lactic acid-based polymer (A) and the plasticizer (B) are melt-mixed, free radicals can be simultaneously generated and reacted. For example, when a biaxial horizontal reactor is used for the polymerization reaction, the lactic acid-based polymer (A) and the plasticizer (B) may be added simultaneously with the radical initiator, and only the radical initiator may be added from the middle of the reactor. May be thrown. Further, it is possible to carry out a mixing reaction while irradiating the above-mentioned electron beam, or to perform a reaction by irradiating an electron beam again to a mixture obtained by melting and mixing the lactic acid-based polymer (A) and the plasticizer (B).

When only the radical initiator is charged in the middle, the lactic acid-based polymer (A) and the plasticizer (B) can be melt-kneaded in advance, so that the temperature at the point where the radical initiator is charged can be lowered. Thus, the radical reaction can proceed slowly, and the reaction can be performed without lowering the activity of the radical initiator. The reaction temperature is 120
Perform in the range of -180 ° C. If the reaction temperature is lower than 120 ° C., the reaction does not proceed sufficiently, and the reaction at a temperature higher than 180 ° C. promotes the deterioration of the radical initiator or accelerates the decomposition reaction of the lactic acid-based polymer by free radicals. Further, since the amount of the plasticizer is also reduced, the physical properties are also reduced. In the case of using a biaxial horizontal reactor, for example, when the reaction is performed at 120 to 180 ° C., the residence time is 5 to 20 minutes, and the reaction proceeds sufficiently, depending on the relationship with the reaction temperature. A graft copolymer of a system polymer and a plasticizer can be obtained.

[0018] The obtained copolymer is a thermoplastic resin having a flexible property in which the plasticizer (B) is contained in the molecular structure. The molding temperature of this copolymer can be set lower than that of polylactic acid alone, and there is little molecular degradation during molding, and it is difficult to color, and a transparent molded article can be obtained. Further, since the molding temperature can be set low, the cooling time after molding can be shortened, and good moldability is exhibited. The flexibility of the copolymer can be controlled by appropriately changing the composition and amount of the plasticizer (B) used. Further, by subjecting the mixture to a reduced pressure in the latter stage of the reaction or after the completion of the reaction, unreacted lactide monomers and reaction by-products remaining in about 1 to 3% can be removed. As a specific method of the decompression treatment, the latter half of the biaxial horizontal reaction apparatus can be maintained at 120 to 160 ° C. and 1 to 50 Torr, and retained and devolatilized for 3 to 15 minutes.
The lactide monomer and the copolymer from which by-products have been removed in this manner can provide an excellent copolymer having greatly improved stability over time.

In a simple blend of a lactic acid-based polymer and a plasticizer, the amount of the plasticizer is reduced due to crystallization of the lactic acid-based polymer, and the flexibility is reduced. In addition, unreacted products and by-products remain and contribute as hydrolysis promoters.

The copolymer of the present invention can be prepared in a well-known reaction vessel in addition to the above-described two-axis horizontal reaction apparatus.
A vertical reaction vessel or a horizontal reaction vessel provided with a shaft or a plurality of shaft stirrers, a horizontal reaction vessel provided with a scraping blade of one or more shafts, or a kneader of one or more shafts, 1
A single or multiple-screw extruder or other reactor may be used alone, or a plurality of reactors may be connected in series or in parallel.

The composition of the present invention can be modified in various ways by adding a secondary additive. Examples of secondary additives include ultraviolet absorbers, pigments, colorants, various fillers, electrostatic agents, release agents, fragrances, antibacterial agents, nucleating agents, stabilizers such as antioxidants and regulators, and the like. , And other similar ones. Furthermore, it is also possible to add and use a plasticizer as a secondary plasticizer as needed.

In the present invention and the following Examples and Comparative Examples, the weight average molecular weight of the polymer is the value measured by GPC analysis in terms of polystyrene, the glass transition point, the crystallization point, and the melting point are the values measured by a scanning differential calorimeter (DSC). It is.

[0023]

The present invention will be described more specifically with reference to examples and comparative examples. In this example, an experiment was conducted using the following lactic acid-based polymer, plasticizer, and peroxide. <Polylactic acid (P1)> 90 parts by weight of L-lactide, D-
Lactide (10 parts by weight) was added and melt-mixed under an inert gas atmosphere. Then, 0.24 parts by weight of tin octylate as a ring-opening polymerization catalyst was polymerized at 190 ° C. for 15 minutes while stirring with a twin-screw kneader, and then 2 mm in diameter. The mixture was extruded with a nozzle, cooled with water and cut to obtain a low-crystalline polylactic acid chip C1. Chip C
1 in nitrogen at 120 ° C. and 1.5 kg / cm ² pressure.
Treat for 2 hours to remove unreacted monomer (lactide)
Chip P1 was obtained. The weight average molecular weight of chip P1 is 16
3,000, the residual monomer (lactide) was 0.5% or less. As a result of measuring DSC, the glass transition temperature was 55.3 ° C., the crystallization temperature was 144.9 ° C., and the melting point was 17
Observed at 5.7 ° C.

<Polylactic acid (P2)> To 75 parts by weight of L-lactide, 25 parts by weight of D-lactide were added and melt-mixed under an inert gas atmosphere, and 0.24 parts by weight of tin octylate as a ring-opening polymerization catalyst was added. 1 at 190 ° C while stirring with a twin-screw kneader
After polymerization for 5 minutes, the mixture was extruded with a nozzle having a diameter of 2 mm, cooled with water and cut to obtain an amorphous polylactic acid chip C2. The chip C2 was heated at 120 ° C. under a pressure of 1.5 kg / cm ^2.
For 12 hours to remove unreacted monomer (lactide) to obtain chip P2. Chip P2 has a weight average molecular weight of 117,000 and a residual monomer (lactide)
Was 1.5% or less. As a result of DSC measurement, the glass transition temperature was 51.7 ° C., and the crystallization temperature and melting point were not observed.

<Polylactic acid (P3)> To 99 parts by weight of L-lactide, 1 part by weight of D-lactide was added and melted and mixed under an inert gas atmosphere, and 0.24 part by weight of tin octylate as a ring-opening polymerization catalyst was added. 1 at 190 ° C while stirring with a twin-screw kneader
After polymerization for 5 minutes, the mixture was extruded with a nozzle having a diameter of 2 mm, cooled with water and cut to obtain a crystalline polylactic acid chip C3. The chip C3 was heated at 120 ° C. under a pressure of 1.5 kg / cm ^2.
For 12 hours to remove unreacted monomer (lactide) to obtain chip P3. Chip P3 has a weight average molecular weight of 188,000 and a residual monomer (lactide)
Was 0.1% or less. As a result of measuring DSC, the glass transition temperature was 60.0 ° C., and the crystallization temperature was 137.3.
° C and melting point was observed at 171.3 ° C.

<Plasticizer: Triacetin (manufactured by Daihachi Chemical Industry Co., Ltd.) (S1)> Acid value: 0.05 or less, hue (APHA): 20 or less, molecular weight: 218, specific gravity (20/20 ° C.): 1 .160 ±
0.003, solubility parameter (HOY): 9.9

<Plasticizer: ADEKA SIZER RS-1000
(Asahi Denka Kogyo Co., Ltd.) (S2)> Acid value: 0.08, hue (APHA): 120, molecular weight:
500-1000, viscosity (25 ° C.): 43 cp, specific gravity (25/25 ° C.): 1.10, solubility parameter (H
OY): 9.7

<Peroxide: Kayahexa AD40C (manufactured by Kayaku Akzo) (O1)> Content: 40%, active oxygen content: 4.4%, molecular weight: 29
0.44, 10 hour half-life temperature: 118 ° C., activation energy: 36.0 kcal / kmol (CAS No.
78-63-7)

Example 1 100 parts by weight of P1, 40 parts by weight of S1, and 2.5 parts by weight of O1 were mixed,
The mixture was melt-mixed on average with a twin-screw extruder at 5 ° C. for 5 minutes, extruded with a nozzle having a diameter of 2 mm, cooled with water and cut to obtain a lactic acid-based polymer chip (PC1). 75 ° C
After drying in vacuum to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. In addition, DSC measurement was performed using the chip PC1. Further, DSC measurement was performed using the chip PC1 which was left in the air at room temperature (25 ° C.) for 3 months.

(Example 2) 100 parts by weight of P1, 40 parts by weight of S2, and 2.5 parts by weight of O1 were mixed, and 180 parts by weight were mixed.
The mixture was melt-mixed for 5 minutes on average with a twin-screw extruder at ℃, extruded with a nozzle having a diameter of 2 mm, cooled with water and cut to obtain a lactic acid-based polymer chip (PC2). 75 ℃ of the chip PC2
After drying in vacuum to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. In addition, DSC measurement was performed using the chip PC2. Further, DSC measurement was performed using the chip PC2 which was left in the air at room temperature (25 ° C.) for 3 months.

Example 3 100 parts by weight of P2, 40 parts by weight of S1, and 2.5 parts by weight of O1 were mixed,
The mixture was melt-mixed for 5 minutes on average with a twin-screw extruder at ℃, extruded with a nozzle having a diameter of 2 mm, cooled with water and cut to obtain a lactic acid-based polymer chip (PC3). The chip PC3 is set at 50 ° C
After drying in vacuum to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PC3. Further, DSC measurement was performed using the chip PC3 which was left in the air at room temperature (25 ° C.) for 3 months.

Example 4 100 parts by weight of P2, 40 parts by weight of S2, and 2.5 parts by weight of O1 were mixed,
The mixture was melt-mixed for 5 minutes on average with a twin-screw extruder at ℃, extruded with a nozzle having a diameter of 2 mm, cooled with water and cut to obtain a lactic acid-based polymer chip (PC4). The chip PC4 is set at 50 ° C
After drying in vacuum to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PC4. Further, DSC measurement was performed using the chip PC4 which was left in the air at room temperature (25 ° C.) for 3 months.

Example 5 100 parts by weight of P3, 40 parts by weight of S1, and 2.5 parts by weight of O1 were mixed, and the mixture was mixed with 180 parts by weight.
The mixture was melt-mixed for 5 minutes on average with a twin-screw extruder at 0 ° C., extruded with a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PC5). 75 ℃ of the chip PC5
After drying in vacuum to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PC5. Further, DSC measurement was performed using Chip PC5 which was left in the air at room temperature (25 ° C.) for 3 months.

Example 6 100 parts by weight of P3, 40 parts by weight of S2 and 2.5 parts by weight of O1 were mixed,
The mixture was melt-mixed for 5 minutes on average with a twin-screw extruder at 0 ° C., extruded with a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PC6). 75 ℃ of the chip PC6
After drying in vacuum to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PC6. Further, DSC measurement was performed using the chip PC6 which was left in the air at room temperature (25 ° C.) for 3 months.

(Comparative Example 1) After P1 was vacuum-dried at 75 ° C to make it absolutely dry, a business card large plate (1 m
mt). DSC measurement was performed using P1. Further, DSC measurement was performed using the chip P1 left in the room temperature (25 ° C.) atmosphere for 3 months.

(Comparative Example 2) After P2 was vacuum-dried at 50 ° C to make it absolutely dry, a business card large plate (1 m
mt). DSC measurement was performed using P2. Further, DSC measurement was performed using the chip P2 left in the air at room temperature (25 ° C.) for 3 months.

(Comparative Example 3) P3 was vacuum-dried at 75 ° C to make it completely dry, and then a business card large plate (1 m
mt). DSC measurement was performed using P3. Further, DSC measurement was performed using the chip P3 left in the room temperature (25 ° C.) atmosphere for 3 months.

(Comparative Example 4) 100 parts by weight of P1 and 40 parts by weight of S1 were mixed, and an average of 5 parts was obtained with a twin-screw extruder at 180 ° C.
The mixture was melt-mixed for 1 minute, extruded with a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PS1). After vacuum drying the chip PS1 at 75 ° C. to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PS1. Further, DSC measurement was performed using the chip PS1 left in the air at room temperature (25 ° C.) for 3 months.

(Comparative Example 5) 100 parts by weight of P1 and 40 parts by weight of S2 were mixed, and an average of 5 parts was obtained with a twin-screw extruder at 180 ° C.
The mixture was melt-mixed for 1 minute, extruded with a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PS2). After the chip PS2 was vacuum dried at 75 ° C. to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PS2. Further, DSC measurement was performed using the chip PS2 which was left in the air at room temperature (25 ° C.) for 3 months.

(Comparative Example 6) 100 parts by weight of P2 and 40 parts by weight of S1 were mixed, and an average of 5 parts was obtained with a twin-screw extruder at 160 ° C.
The mixture was melt-mixed for 1 minute, extruded through a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PS3). After vacuum drying the chip PS3 at 50 ° C. to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PS3. Further, DSC measurement was performed using the chip PS3 left in the air at room temperature (25 ° C.) for 3 months.

(Comparative Example 7) 100 parts by weight of P2 and 40 parts by weight of S2 were mixed, and an average of 5 parts was obtained with a twin-screw extruder at 160 ° C.
The mixture was melt-mixed for 1 minute, extruded with a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PS4). After vacuum drying the chip PS4 at 50 ° C. to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PS4. Further, DSC measurement was performed using the chip PS4 which was left in the air at room temperature (25 ° C.) for 3 months.

(Comparative Example 8) 100 parts by weight of P3 and 40 parts by weight of S1 were mixed, and an average of 5 parts was mixed with a twin-screw extruder at 180 ° C.
The mixture was melt-mixed for 1 minute, extruded through a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PS5). After the chip PS5 was vacuum dried at 75 ° C. to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PS5. Further, DSC measurement was performed using the chip PS5 left in the room temperature (25 ° C.) atmosphere for 3 months.

(Comparative Example 9) 100 parts by weight of P3 and 40 parts by weight of S2 were mixed, and an average of 5 parts was mixed with a twin-screw extruder at 180 ° C.
The mixture was melt-mixed for 1 minute, extruded with a nozzle having a diameter of 2 mm, cooled with water, and cut to obtain a lactic acid-based polymer chip (PS6). After vacuum drying the chip PS6 at 75 ° C. to make it absolutely dry, a business card large plate (1 mmt) was prepared by injection molding. DSC measurement was performed using the chip PS6. Further, DSC measurement was performed using the chip PS6 which was left in the air at room temperature (25 ° C.) for 3 months. Table 1 shows the results of Examples 1 to 6 and Comparative Examples 1 to 9.

[Table 1]

The polymers of Comparative Examples 1 to 3 have a high glass transition point and do not have sufficient flexibility. In the polymers of Comparative Examples 4 to 9, the melt viscosity is so low that the MFR cannot be measured, and molding is difficult. Further, the glass transition point increases, the flexibility is lost, and the stability over time is poor. Various moldings were possible with the polymer compositions of Examples 1 to 6. In addition, it was found that the glass transition point was low, sufficient flexibility was provided, and transparency was also obtained. Furthermore, the stability over time has also been improved,
It can be seen that the balance between flexibility, moldability and stability over time is excellent.

According to the present invention, since a plasticizer is graft-polymerized to a lactic acid-based polymer, it can be decomposed in a natural environment, has transparency and flexibility, and has moldability and stability over time. The present invention can provide a biodegradable polylactic acid-based polymer composition and a molded article having excellent properties. This biodegradable polylactic acid-based polymer is used for packaging materials, industrial materials, industrial supplies,
Although it can be used for various applications such as containers, it is particularly suitable as a material for films, tapes and sheets requiring flexibility and transparency. Also, because of the structure containing a plasticizer in the graft chain, it has excellent stability over time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 167/04 C09D 167/04 4J029 C09J 167/04 C09J 167/04 4J031 D01F 6/62 305 D01F 6/62 305Z 4J038 D04H 1/42 D04H 1/42 T 4J040 D21H 19/28 D21H 19/28 4L035 // B29C 45/00 B29C 45/00 4L047 47/00 47/00 4L055 49/00 49/00 (72) Inventor Eiichi Koseki 1-term, Kuwabaracho, Nishinokyo, Nakagyo-ku, Kyoto F-term in Shimadzu Corporation (reference) 4J002 BN171 CF181 CF191 EH056 EH096 EH146 EH156 FD026 GG00 GH01 GJ01 GK00 GK04 4J029 AA02 AA05 AB07 AC01 AC02 AC05 AD01 AE01 AE02 AE03 AE11 AE13 AE18 BA02 BA03 BA04 BA05 BA07 BA08 BA09 BA10 CA02 CA04 CA06 CB05A CB06A EA02 EA03 EG02 EG03 EG04 EG01 E03 E03 E03 E03 E03 E03 E03 H03 FC3 AE13 AF10 AF11 AF12 AF13 AF15 4J038 CP121 DD011 DD241 JA21 JA59 JA61 JA62 JC24 KA10 MA14 4J040 ED011 HB10 HB24 HB32 HB34 HD44 JA09 JB09 KA31 LA01 LA05 4L035 AA05 GG06 HH10 KK05 4A037AA29A48A29A29A48A29A48A29A48A30A48 EA32 FA11 FA14

Claims (4)

[Claims] 1. A plasticizer (B) having a weight average molecular weight of 100 to 5,000 and a solubility parameter (SP) value of 9.0 to 11.0 contains at least 50% by weight or more of a lactic acid component by weight fraction, A lactic acid-based composition characterized by being graft-polymerized to a lactic acid-based polymer (A) having a weight average molecular weight of 10,000 or more. 2. The lactic acid composition according to claim 1, wherein the amount of the plasticizer (B) is 5 to 500 parts by weight based on 100 parts by weight of the lactic acid polymer (A). 3. The plasticizer (B) is a phthalate ester, an adipic ester, a glycolic acid derivative, an ether ester derivative, a glycerin derivative, an alkyl phosphate, a dialkylater, a diester, a tricarboxylate, a polyester, a polyglycol diester, an alkylalkyl. The lactic acid composition according to claim 1 or 2, wherein the lactic acid composition is a single or a plurality of mixtures selected from the group consisting of a lateter diester, an aliphatic diester, an alkylate monoester, a citrate ester, and an aromatic hydrocarbon. 4. A film, sheet, coated paper, blow-molded product, injection-molded product, extruded product, fiber or non-woven fabric, viscous / adhesive agent, paint agent, packaging material comprising the composition according to claim 1. .