JP2003105182A - Plasticizer for lactic acid-based polymer, resin composition and molded article containing the plasticizer and lactic acid-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasticizer with low volatility which gives a lactic acid-based polymer molded article having excellent aging stability and flexibility under use conditions and no bleed-out of a plasticizer, the plasticizer and a lactic acid-based polymer And a molded article thereof. SOLUTION: The dibenzoate of polyethylene glycol having a number average molecular weight of 150 or more, particularly a number average molecular weight of 20
Plasticizer for polylactic acid comprising polyethylene glycol dibenzoate or polyethylene glycol dibenzoate having a number average molecular weight of 300, a lactic acid-based polymer composition containing a plasticized lactic acid-based polymer containing the plasticizer as a main component, and the same. Molding.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a plasticizer for a lactic acid-based polymer, a lactic acid-based polymer composition containing the plasticizer and the lactic acid-based polymer, and a lactic acid-based polymer molding obtained by molding the lactic acid-based polymer composition. Regarding the body

[0002]

2. Description of the Related Art In recent years, from the viewpoint of nature protection, a disposal method after use of general-purpose plastics such as polyethylene, polypropylene, polystyrene and polyvinyl chloride, which are not decomposed in a natural environment, has become a problem. Most of these general-purpose plastics are incinerated or landfilled without being reused or recycled.

However, in the case of incineration, polyethylene, polypropylene, and polystyrene have a high calorific value and easily damage the incinerator. It is known that polyvinyl chloride produces harmful substances such as dioxins when incinerated. In landfills, these general-purpose plastics are chemically stable and remain semi-permanently, causing serious shortages in landfills.

In order to solve these problems, a biodegradable polymer which decomposes in a natural environment and its molded article are required, and a copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, polycaprolactone, poly Studies on spontaneously-degradable aliphatic polyester resins such as butylene succinate have been actively conducted. One of them is a lactic acid type polymer and its copolymer.

Polylactic acid is biodegradable and has a burning calorie of about 1/3 to 1 of polyethylene and polypropylene.
It is as low as / 2, it does not damage the incinerator, and it does not generate toxic gases such as hydrogen chloride, NOx, SOx, especially dioxin during incineration. Furthermore, since polylactic acid can utilize renewable plant resources (corn, etc.) as a starting material every year, it does not need to use fossil resources such as petroleum, and is expected as a substitute material for general-purpose plastics. .

However, polylactic acid itself has excellent rigidity because it has a high crystallinity and a rigid molecular structure, but it has the drawback of being inflexible and brittle. Until now, applications such as molded products and films that require flexibility,
For example, agricultural bags, mulch film, vegetation sheets, curing sheets, agricultural and horticultural and forestry materials such as animal and insect repellent nets, slope protection materials, soil reinforcement materials, civil engineering and construction materials such as drain materials, food packaging films, and stretch films. It could hardly be used for applications such as food packaging materials such as, sanitary goods materials such as paper diapers and sanitary goods packaging, daily life materials such as draining nets, garbage bags and shopping bags. Therefore, general-purpose resins such as polyethylene, polypropylene and polyvinyl chloride have been used for such applications requiring flexibility.

As a method for solving such a problem, a method of adding a plasticizer component to a lactic acid-based polymer has been disclosed. For example, (1) Japanese Patent Application Laid-Open No. 4-335060 discloses a composition in which a plasticizer is added to a lactic acid-based polymer, and as a plasticizer having a good plasticizing effect, diisobutyl adipate, Although dioctyl sebacate and the like are described, its plasticizing effect is small, and its flexibility is practically insufficient for use in general film applications.

Further, the publication describes dioctyl phthalate as a phthalic acid plasticizer. However, dioctyl phthalate has drawbacks such as a small plasticizing effect, easy occurrence of bleed-out, and easy volatilization.

(2) JP-A-8-34913 and JP-A-11-116788 describe a composition obtained by adding tributyl acetylcitrate and triacetin as a plasticizer to a lactic acid-based polymer. Although tributyl acetyl citrate and triacetin have a plasticizing effect, they have drawbacks that they are highly volatile and bleed out easily.

(3) JP-A-8-199052, JP-A-8-199053, and JP-A-8-2835
In JP-A-57-57, it is proposed to use polyethylene glycol dialkyl ester as a plasticizer. However, when these plasticizers are used, the flexibility is high, but the volatility is high, and bleed out easily occurs. It has drawbacks.

Therefore, the molded articles obtained by the conventional methods described in the above (1) to (3) are not always sufficient in stability over time.

(4) Japanese Patent Laid-Open No. 2000-136300 describes polypropylene glycol dibenzoate as a plasticizer for lactic acid-based polymers. These plasticizers have low volatility and little bleed-out, but have low flexibility and cannot be said to have sufficient practicality.

As is apparent from these publications, a lactic acid-based polymer molded body having sufficiently low volatility, excellent stability over time, and excellent flexibility is obtained under the conditions of daily use. Moreover, there is a strong demand for a plasticizer that does not bleed out from a lactic acid-based polymer molded body.

[0014]

An object of the present invention is to produce a molded product which is excellent in stability over time and flexibility and has no plasticizer bleed-out under daily use conditions. It is intended to provide a plasticizer for polymers, a lactic acid-based polymer composition containing the plasticizer and a lactic acid-based polymer, and a molded article obtained by molding the lactic acid-based polymer composition.

[0015]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have added a specific polyethylene glycol dibenzoate as a plasticizer component to a lactic acid-based polymer to prepare a lactic acid-based polymer composition. It was found that, by molding this, a lactic acid-based polymer molded product having sufficiently low volatility under normal use conditions, flexibility, and no plasticizer bleed-out can be obtained, and based on such findings Based on this, the present invention has been completed.

That is, the present invention provides a plasticizer for a lactic acid-based polymer comprising the following polyethylene glycol dibenzoate, a lactic acid-based polymer composition containing the plasticizer and a molded article thereof.

Item 1 A plasticizer for a lactic acid-based polymer, which comprises dibenzoate of polyethylene glycol having a number average molecular weight of 150 or more.

Item 2 The plasticizer for lactic acid-based polymers according to Item 1, wherein the polyethylene glycol has a number average molecular weight of 150 to 5,000.

Item 3 A lactic acid-based polymer composition containing a lactic acid-based polymer and a plasticizer for a lactic acid-based polymer, which comprises dibenzoate of polyethylene glycol having a number average molecular weight of 150 or more.

Item 4 The lactic acid-based polymer composition according to Item 3, wherein the polyethylene glycol has a number average molecular weight of 150 to 5,000.

Item 5 The lactic acid-based polymer composition according to Item 3 or 4, wherein the lactic acid-based polymer has a weight average molecular weight of 50,000 or more.

Item 6. The lactic acid-based polymer composition according to any one of claims 3 to 5, which contains 1 to 300 parts by weight of the plasticizer for lactic acid-based polymer with respect to 100 parts by weight of the lactic acid-based polymer.

Item 7 A molded product obtained by molding the lactic acid-based polymer composition according to any one of Items 3 to 6 above.

Item 8 The molded article according to Item 7 in the form of a sheet or film.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The plasticizer for lactic acid-based polymer of the present invention The polyethylene glycol dibenzoate used as the plasticizer for lactic acid-based polymer in the present invention is esterified with benzoic acid at both terminals (OH groups) of the polyethylene glycol moiety. It is characterized by having a structured structure.

There is no particular limitation on the average molecular weight of polyethylene glycol, which is a raw material of the polyethylene glycol dibenzoate plasticizer, but when the polyethylene glycol dibenzoate has a too high molecular weight, the stability of the lactic acid-based polymer composition with time becomes insufficient. The low-molecular-weight polyethylene glycol dibenzoate is not preferable because the low-temperature characteristics deteriorate. Generally, the number average molecular weight of polyethylene glycol is 150 or more, and particularly 150 to 500.
0, preferably 200 to 2000, more preferably 20
0 to 600.

Examples of such polyethylene glycol dibenzoate include polyethylene glycol dibenzoate having a number average molecular weight of 150 and number average molecular weight of 200.
Polyethylene glycol dibenzoate, number average molecular weight 300 polyethylene glycol dibenzoate, number average molecular weight 400 polyethylene glycol dibenzoate, number average molecular weight 500 polyethylene glycol dibenzoate, number average molecular weight 600 polyethylene glycol dibenzoate Etc. Among them, polyethylene glycol dibenzoate having a number average molecular weight of 200 and polyethylene glycol dibenzoate having a number average molecular weight of 300 are particularly preferable.

The polyethylene glycol dibenzoate used in the present invention can be produced by a conventionally known method. Specifically, esterification reaction of benzoic acid and polyethylene glycol, alkyl (especially C1-C4)
Benzoate and polyethylene glycol or benzoic acid and polyethylene glycol diester (especially di (C1-C
It can be produced by a transesterification reaction with (4 alkyl) ester), a reaction between benzoyl chloride and polyethylene glycol, or the like.

The conditions for these reactions can be ordinary conditions. For example, the esterification reaction is performed by adding 2 mol or more (particularly about 2.1 to 3 mol) of benzoic acid to 1 mol of polyethylene glycol in the presence or absence of a solvent such as xylene or toluene, and para. It is carried out under a temperature condition of about 100 to 250 ° C. using an acid catalyst such as toluenesulfonic acid or tetrabutoxytitanate or a Lewis acid catalyst. In the transesterification reaction, 2 mol or more (particularly about 2.1 to 3 mol) of alkyl (especially C1 to C4) benzoate is used in the presence or absence of a solvent such as xylene or toluene, relative to 1 mol of polyethylene glycol. Under and with a metal oxide such as calcium oxide, tetrabutoxy titanate or a Lewis acid catalyst, 150-250
It is carried out under a temperature condition of about ℃. The reaction between benzoyl chloride and polyethylene glycol is 2 mol or more (especially 2.1 to
About 3 mol) benzoyl chloride in the presence or absence of a solvent such as acetone or methyl ethyl ketone, and in the presence of an amine such as pyridine or sodium hydroxide or an alkali at a temperature of about 30 to 150 ° C. Done in.

Lactic acid-based polymer The "lactic acid-based polymer" as the main component according to the present invention includes (a) lactic acid homopolymer, (b) lactic acid copolymer, and
(c) Examples include blend polymers of at least one selected from the group consisting of lactic acid homopolymers and lactic acid copolymers with other polymers.

The lactic acid component which is a raw material of the lactic acid-based polymer is not particularly limited, but L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof, or
L-lactide, D-lactide, which is a lactic acid cyclic dimer, me
So-lactide or mixtures thereof can be used.

As lactic acid, the ratio of L-form to D-form (L / D)
Is not particularly limited, but a higher optical purity is preferable in order to obtain a high melting point. Specifically, as the lactic acid, it is preferable to include L-form in an amount of 80 mol% or more, and particularly L-form in an amount of 95 mol% or more in the total lactic acid. Also, regarding lactide, it is preferable that the L-form is contained in an amount of 80 mol% or more, and particularly the L-form is contained in an amount of 95 mol% or more in the total lactide.

Of these lactic acid polymers, the weight average molecular weight of lactic acid homopolymer and lactic acid copolymer is not particularly limited and can be appropriately selected from a wide range, but is preferably 50,000 or more, more preferably 50,000 to 500,000, further preferably Is 1
It is from 0,000 to 500,000.

<Lactic acid homopolymer> Lactic acid homopolymers used in the present invention include L-lactic acid, D-lactic acid and DL-lactic acid.
Direct dehydration condensation of lactic acid or a mixture thereof, or
A polymer obtained by ring-opening polymerization of a lactic acid cyclic dimer lactide such as L-lactide, D-lactide, meso-lactide or a mixture thereof can be exemplified.

<Lactic Acid Copolymer> A lactic acid copolymer is a random or block copolymer of the above-mentioned lactic acid monomer, lactide or lactic acid homopolymer and another copolymerizable component.

In this case, as the lactic acid homopolymer used for producing the lactic acid copolymer, a wide range of lactic acid homopolymers can be used, but a weight average molecular weight of about 1,000 to 200,000,
Preferably, it is desirable to use the one of about 5,000 to 100,000.

Examples of the other copolymerizable component include compounds having two or more functional groups capable of forming an ester bond in the molecule, such as a) dicarboxylic acid, b) polyhydric alcohol, and c) lactic acid. Other than hydroxycarboxylic acid, d) lactone, etc., and e) at least one selected from the group consisting of various polyesters, various polyethers, various polycarbonates and the like composed of these various constituent components.

As the a) dicarboxylic acid, specifically, a linear or branched saturated or unsaturated aliphatic dicarboxylic acid having 4 to 50 carbon atoms, particularly 4 to 20 carbon atoms, or 8 to 2 carbon atoms.
Examples thereof include an aromatic dicarboxylic acid having a number of 0 and a polyether dicarboxylic acid having a number average molecular weight of 2000 or less, particularly 1000 or less.

Particularly preferred are straight chain aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as succinic acid, adipic acid, sebacic acid and decanedicarboxylic acid, and aromatic dicarboxylic acids such as phthalic acid, terephthalic acid and isophthalic acid. .

The polyether dicarboxylic acid is preferably a dicarboxylic acid having a carboxyl group at both ends of a polyalkylene ether such as polyethylene glycol, polypropylene glycol, polybutylene glycol or polyethylene polypropylene glycol, and among them, particularly a number average molecular weight. Is 2000 or less, preferably 1000 or less, and more preferably 178 to 1000.

Examples of the polyhydric alcohol b) include aliphatic polyols, aromatic polyhydric alcohols, and polyalkylene ethers.

The aliphatic polyol has 2 to 4 hydroxyl groups such as butanediol, hexanediol, octanediol, decanediol, 1,4-cyclohexanedimethanol, glycerin, sorbitan, trimethylolpropane and neopentyl glycol. Examples thereof include aliphatic polyols having 2 to 50 carbon atoms, particularly 2 to 20 carbon atoms.

Examples of the aromatic polyhydric alcohols include aromatic diols having 6 to 20 carbon atoms such as bis- (ortho, meta or para) hydroxymethylbenzene and hydroquinone, and bisphenols such as bisphenol A and bisphenol F. Aromatic diols having a number average molecular weight of 2000 or less, particularly a number average molecular weight of 1000 or less, which are obtained by addition reaction of an alkylene oxide having 2 to 4 carbon atoms (in particular, ethylene oxide, propylene oxide, butylene oxide, etc.) can be exemplified.

The above polyalkylene ethers include
Ether glycols having a number average molecular weight of 2000 or less, particularly 1000 or less, such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol, can be mentioned.

C) As the hydroxycarboxylic acid,
C2-C18 hydroxycarboxylic acids such as glycolic acid and hydroxybutylcarboxylic acid (excluding lactic acid)
Is mentioned.

D) As the lactone, glycolide,
ε-caprolactone glycolide, ε-caprolactone,
Examples include β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone and δ-valerolactone.

E) The various polyesters, various polyethers, and various polycarbonates of the above e) can be used without particular limitation as long as they have been conventionally used for producing lactic acid copolymers. As 1000 to 150,000, preferably 50
The range of 00 to 100,000 is recommended.

Among the above various polyesters, various polyethers and various polycarbonates, it is particularly preferable to use polyester as a comonomer. As the polyester as the comonomer, for example, an aliphatic polyester composed of an aliphatic dicarboxylic acid and an aliphatic diol is preferable.

The aliphatic dicarboxylic acid which is one of the constituents of the above aliphatic polyester has 4 carbon atoms such as succinic acid, adipic acid, sebacic acid and decanedicarboxylic acid.
Although a straight-chain aliphatic dicarboxylic acid of -20 is preferable, those having a side chain or a double bond can also be used.

As the aliphatic diol which is the other constituent component of the above aliphatic polyester, ethylene glycol,
Propanediol, butanediol, hexanediol, octanediol and other aliphatic diols and polyalkylene ethers (homopolymers or copolymers) such as polyethylene glycol, polypropylene glycol and polybutylene glycol, and polyalkylene carbonates. Is exemplified. As the polyalkylene ether and polyalkylene carbonate, those having a number average molecular weight of 2000 or less, particularly 1000 or less are preferable.

In addition to such aliphatic dicarboxylic acids and aliphatic diols, lactic acid, glycolic acid, and
Hydroxycarboxylic acid such as hydroxybutylcarboxylic acid, butyrolactone, lactone such as ε-caprolactone, a compound having an ester bond-forming functional group such as aromatic dicarboxylic acid, as long as the effect of the present invention is not impaired, It can also be used as a constituent component of the aliphatic polyester.

Among the lactic acid copolymers described above,
In particular, lactic acid and the hydroxycarboxylic acids (excluding lactic acid)
And a lactic acid / diol / dicarboxylic acid copolymer (particularly, a copolymer of lactic acid, the aliphatic diol, and the aliphatic dicarboxylic acid), a copolymer of lactic acid and the lactone, and the like are preferable.

In the lactic acid copolymer used in the present invention, the copolymerization components a) to e) are preferably less than 50% by weight based on the total weight of the lactic acid-based polymer containing lactic acid as a main component.
When the amount of the copolymer component is large, the crystallinity and heat resistance of the lactic acid-based polymer tend to decrease, so the ratio of the copolymer component is appropriately selected depending on the purpose and application, but the total weight of the lactic acid-based polymer is On the other hand, it is recommended that the amount is preferably 1 to 30% by weight, more preferably 5 to 20% by weight.

<Blend Polymer> The blend polymer contains at least one selected from the group consisting of the lactic acid homopolymers and lactic acid copolymers as a main component, and further, as another polymer, polyesters such as aliphatic polyesters and aromatic polymers. Blends containing polyesters or mixtures thereof. As the other polymer, an aliphatic polyester is particularly preferable from the viewpoint of biodegradability.

The blending ratio of the other polymer is appropriately selected depending on the purpose and application, but at least one kind selected from the group consisting of the lactic acid homopolymer and lactic acid copolymer described above is used.
It is preferably in the range of 5 to 50% by weight with respect to 50% by weight of polyester. If the amount of polyester is less than 5% by weight, flexibility and impact resistance tend to be difficult to obtain, and
When the content exceeds 10% by weight, the polyester tends to bleed out on the surface of the molded product, and transparency tends to be difficult to obtain. At least one kind selected from the group consisting of lactic acid homopolymers and lactic acid copolymers 94 to 6
The range of 6 to 40% by weight of polyester is more preferable with respect to 0% by weight.

If the molecular weight of the polyester in such a blended polymer is too low, mechanical properties will be insufficient, which is not preferable. The polyester has a weight average molecular weight of preferably 10,000 or more, more preferably 30,000 or more, further preferably 50,000 or more, and usually 50,000.
The ones up to 300,000 are most widely used.

The aliphatic dicarboxylic acid which is a constituent component of the aliphatic polyester is preferably a straight chain aliphatic dicarboxylic acid having 4 to 20 carbon atoms such as succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, etc. And those having a double bond can also be used.

The aliphatic diol which is the other component is an aliphatic diol having 2 to 20 carbon atoms such as ethylene glycol, propanediol, butanediol, hexanediol and octanediol, and polyethylene glycol, polypropylene glycol, polybutylene. Examples are polyalkylene ethers (homopolymers or copolymers) such as glycols and polyalkylene carbonates. As the polyalkylene ether and polyalkylene carbonate, those having a number average molecular weight of 2000 or less, particularly 1000 or less are preferable.

In addition to such aliphatic dicarboxylic acids and aliphatic diols, lactic acid, glycolic acid, and
Hydroxycarboxylic acid such as hydroxybutylcarboxylic acid, butyrolactone, lactone such as ε-caprolactone, a compound having an ester bond-forming functional group such as aromatic dicarboxylic acid, as long as the effect of the present invention is not impaired, It can also be used as a constituent component of the aliphatic polyester.

The above-mentioned aliphatic polyester can be prepared by subjecting the above-mentioned aliphatic dicarboxylic acid and aliphatic diol (and the above-mentioned compound having an ester bond-forming functional group, if necessary) to a tetraester as an esterification catalyst according to a conventionally known method. Using isopropyl titanate, a reaction temperature of 200 to 22
Finally, at 0 ° C, under reduced pressure of 100 to 500 Pa, 8 to 1
It can be produced by carrying out an esterification reaction for 2 hours.

<Method for Producing Lactic Acid-Based Polymer> The lactic acid-based polymer, which is the main component of the composition of the present invention, can be produced by a conventionally known method.

Specifically, the lactic acid homopolymer can be produced by direct dehydration condensation from a lactic acid monomer or by ring-opening polymerization of a lactic acid cyclic dimer lactide (see, for example, JP-A-7-33861, Kaisho 59-961
No. 23).

L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof can be used as the lactic acid raw material for the direct dehydration condensation. In addition, L-lactide, D-lactide, meso-lactide, or a mixture thereof can be used as a lactic acid raw material when performing ring-opening polymerization.

The synthesis, purification and polymerization procedure of lactide are carried out, for example, in US Pat. No. 4,057,537, Published European Patent Application No. 261572, Polymer Bu.
lletin, 14, 491-495 (1985) and Makromol Chem, 187, 1611-16.
28 (1986) and the like.

The catalyst used in the polymerization reaction is not particularly limited, but known polymerization catalysts such as esterification catalysts, transesterification catalysts and ring-opening polymerization catalysts can be used. Specifically, tin lactate, tin tartrate, tin dicaprylate, tin dilaurate, tin dipalmitate,
Tin compounds such as tin distearate, tin dioleate, α-tin naphthoate, β-naphthoate, tin dioctylate, tin powder, tin oxide; zinc dust, zinc halide, zinc oxide, organic zinc compounds; Titanium compounds such as tetraisopropoxy titanate; zirconium compounds such as zirconium isopropoxide; antimony compounds such as antimony trioxide; bismuth compounds such as bismuth oxide; aluminum compounds such as aluminum oxide and aluminum isopropoxide. It is illustrated. Among these, a catalyst made of tin or a tin compound is particularly preferable from the viewpoint of activity. The amount of these catalysts used is preferably 0.001 to 5% by weight based on the total weight of the reaction components,
More preferably 0.002 from the viewpoint of reaction rate, coloring, etc.
~ 0.5% by weight.

The polymerization reaction is usually carried out in the presence of the above catalyst at 100
It is preferable to carry out at a temperature of 250 to 250 ° C, preferably 125 to 230 ° C, more preferably 150 to 200 ° C. It is also possible to carry out two-step polymerization.

Further, in order to suppress the decomposition and coloration of the lactic acid-based polymer, it is preferable to carry out the reaction in an atmosphere of an inert gas such as nitrogen or argon. Further, the reaction raw materials should be dehydrated and dried before the reaction. Is preferred.

As the lactic acid-based polymer, a copolymer of lactic acid and the hydroxycarboxylic acid of the above c) or lactic acid and the above d)
In the case of using the copolymer with the lactone of, the method for producing the copolymer includes direct dehydration polycondensation of lactic acid and the hydroxycarboxylic acid of the above c), or lactic acid cyclic dimer (lactide) and the above d. A ring-opening polymerization of a lactone of 1) with a fatty acid metal salt such as tin caproate as a catalyst as appropriate (for example, JP-A-6-306264,
U.S. Pat. No. 4,057,537).

As the lactic acid type polymer, lactic acid / diol /
When a dicarboxylic acid copolymer is used, the method for producing the copolymer is not particularly limited, but a method of directly dehydrating a mixture of lactic acid, an aliphatic diol and an aliphatic dicarboxylic acid (for example, US Pat. No. 5,428,126). ), A method of reacting a cyclic dimer of lactic acid with a polyester composed of an aliphatic dicarboxylic acid component having various constituent ratios and a diol component in the presence of a ring-opening polymerization catalyst (see, for example, Japanese Patent Application Laid-Open No. H7-18753).
No. 173266), (i) lactic acid homopolymer, and (i
i) A method of reacting a polyester comprising an aliphatic diol and an aliphatic dicarboxylic acid component in the presence of an organic solvent (for example, EP0712880A2 publication) and the like.

The blended polymer used in the present invention can be obtained by blending at least one selected from the group consisting of the lactic acid homopolymers and lactic acid copolymers and the other polymer according to a conventional method.
The blending method is not particularly limited, but for example, it may be mixed in a molten state or a solution state by mechanical stirring or the like, or a conventionally known method of mixing in a powder form or a particle form and melting or dissolving can be adopted. . Specifically, the above blend polymer can be used by using a Banbury type mixer, an extruder, a reactor, a roll or the like.

Lactic acid-based polymer composition The lactic acid-based polymer composition of the present invention contains the lactic acid-based polymer and the plasticizer for lactic acid-based polymer of the present invention.

The flexibility of the molded article obtained from the lactic acid-based polymer composition according to the present invention can be controlled by the addition amount of the polyethylene glycol dibenzoate plasticizer of the present invention, and the addition amount is 100 parts by weight of the lactic acid-based polymer. To 1 to 30
0 parts by weight is preferred. If it is less than 1 part by weight, sufficient flexibility is difficult to obtain, and if it exceeds 300 parts by weight, the plasticizer bleeds out on the surface of the lactic acid-based polymer composition, and deterioration over time easily occurs, which is not suitable for practical use.

The amount of the polyethylene glycol dibenzoate added is more preferably 5 to 150 parts by weight, further preferably 10 to 100 parts by weight. Within this range, the lactic acid-based polymer molding is generally used. Under the conditions, for example, a temperature condition of 20 to -20 ° C, it exhibits sufficient properties in thermal stability and flexibility. In particular, 20 to 100 parts by weight is preferable for applications requiring flexibility, and 10 to 30 parts by weight is preferable for applications requiring impact resistance. The polyethylene glycol dibenzoate blended with the lactic acid-based polymer is usually used alone, but if necessary, two or more kinds may be used in combination.

The method of blending polyethylene glycol dibenzoate with the lactic acid-based polymer is not particularly limited, and a kneading device conventionally known in this field can be adopted.
For example, extruders, reactors, kneaders, rolls and combinations thereof can be used. As an extruder,
A single-screw extruder or a twin-screw extruder can be used, but a twin-screw extruder is preferable, and more preferably, one having a vent port is used for subsequently removing residual volatile components under reduced pressure after kneading. This mixing and kneading is usually 120 to 2
It is carried out at a temperature of 50 ° C, preferably 150-200 ° C.

Further, a plasticizer may be added at various stages of the polymerization reaction process starting from lactide, lactic acid monomer, lactic acid oligomer and its copolymerization component.

The obtained lactic acid-based polymer composition of the present invention is usually produced in the form of pellets.

Further, in the lactic acid-based polymer composition of the present invention, if necessary, conventionally known plasticizers and additives other than polyethylene glycol dibenzoate having a number average molecular weight of 150 or more are used as long as the effects of the present invention are not impaired. You may mix. Examples of such additives include anti-blocking agents, heat stabilizers, light stabilizers, antioxidants, ultraviolet absorbers,
Matting agent, pigment, colorant, various fillers, antistatic agent,
Examples thereof include release agents, fragrances, lubricants, flame retardants, foaming agents, fillers, antibacterial agents, nucleating agents and the like.

Molded Product of the Present Invention The molded product obtained by molding the lactic acid-based polymer composition of the present invention thus obtained has good biodegradability,
In particular, it is excellent in decomposability in compost and can be decomposed in 3 to 6 months until the outer shape is not maintained. However, under daily use conditions, the volatilization loss is small and the performance as a molded article is maintained, which is excellent in temporal stability.

The lactic acid-based polymer composition of the present invention is produced by the same extrusion molding, injection molding, vacuum molding, or the like as general plastics.
It can be applied to molding such as pressure molding, film, sheet, tape, label, laminate, fiber, knit, woven fabric, non-woven fabric,
Papers, felts, plates, rods, tubes, porous molded products, various containers, various parts, and other molded products can be easily obtained.

The molding conditions can be the same as the conventional one. For example, in the case of extrusion molding, the lactic acid-based polymer composition (pellets) is heated and melted in a cylinder and continuously extruded from the die at a die temperature higher than the melting point of the lactic acid-based polymer composition. Is preferred. In the case of injection molding, the lactic acid-based polymer composition (pellets) is heated and melted in a cylinder, injected into a mold at a temperature equal to or lower than the melting point of the lactic acid-based polymer composition, and then cooled and solidified for molding. Is preferred.

The lactic acid-based polymer molding of the present invention can be used as a substitute for the field of application of a packaging material such as a dust bag or the like, which is formed into a sheet or film requiring flexibility, or a soft PVC material such as a soft tube. , Damping materials, agricultural / horticultural materials, food packaging materials, hygiene materials, daily necessities, industrial materials, automobile interior materials,
It is not limited to these.

The method for producing a molded article from the lactic acid-based polymer composition of the present invention can be applied to extrusion molding, injection molding, vacuum molding, pressure molding and the like similar to general plastics. Various molded products such as containers can be easily obtained.

[0083]

EXAMPLES The present invention will be specifically described with reference to Examples and Comparative Examples below. However, the invention is in no way limited by these examples. In addition, "parts" of Examples and Comparative Examples
Are all on a weight basis.

In the examples and comparative examples, the weight average molecular weight of the lactic acid-based polymer was determined by using HPLC manufactured by Shimadzu Corporation,
The polystyrene conversion value by GPC analysis and the composition ratio of L-form and D-form were analyzed using Shimadzu HPLC.

Production Example In a 0.5 L or 1 L flask equipped with a stirrer, a thermometer, a reflux condenser with a water separator, and a nitrogen gas introduction tube, 1 benzoic acid was added.
28.2 g (1.05 mol), a predetermined amount of polyethylene glycol (0.5 mol), and 0.2 wt% of tetrabutoxy titanate catalyst and 5 wt% of xylene were added to the total weight of the reaction components. , Under nitrogen atmosphere, 220
The dehydration reaction was performed at 5 ° C. for about 5 to 10 hours.

After cooling to room temperature, neutralizing with a 5% NaOH aqueous solution, washing with warm water, and then dehydration and dexylene at 120 to 150 ° C. and a reduced pressure of about 1.5 kPa for 0.5 to 1 hour to give a predetermined polyethylene. Glycol dibenzoate was obtained. As a result of FT-IR analysis, absorption of carboxyl group disappeared and absorption of ester group (1720 cm ⁻¹ ) was observed, so that a predetermined polyethylene glycol dibenzoate described in Examples 1 to 7 below was produced. I confirmed that.

PEG # 300 described in Comparative Examples 1 to 4 below was prepared in the same manner as above using an appropriate starting material.
Dioctate, dipropylene glycol dibenzoate and diethylene glycol dibenzoate were obtained.

Examples 1 to 7 and Comparative Examples 1 to 5 Lactic acid-based polymers (weight average molecular weight 200,000, L-lactic acid / D
-Lactic acid = 99/1, hereinafter abbreviated as "PLA") 100
An extruder having a diameter of 20 mm (length / diameter ratio = 19, manufactured by Toyo Seiki Co., Ltd., trade name " The resin composition was kneaded at 200 ° C. using a “Labo Plastomill”, and the resin composition extruded by a nitrogen purge was cooled with water and then pelletized by a pelletizer.

The obtained pellets were hot pressed at 200 ° C. to prepare a sheet having a size of 200 mm × 250 mm and a thickness of 1 mm.

A test piece was cut out from this sheet and a Crushberg type tester was used as an index of flexibility.
The torsional rigidity at 20 ° C, 0 ° C and -20 ° C was measured. The smaller the value of torsional rigidity, the better the flexibility.

The test piece was placed in a gear oven at 80 ° C., and the volatilization loss after 10 days was measured.

The presence or absence of bleed-out of the plasticizer was evaluated visually by leaving the test piece in a constant temperature room at 25 ° C. and a humidity of 60% for 30 days.

The results are shown in Table 1. In Table 1, polyethylene glycols having number average molecular weights of 200, 300, 600 and 1000 are respectively PEG # 200 and PEG #.
Abbreviated as 300, PEG # 600, and PEG # 1000.

[0094]

[Table 1]

In Table 1, the torsional rigidity, which is an index of flexibility, was judged to be acceptable when it was 0.1 MPa or less at 20 ° C., 0.45 MPa or less at 0 ° C., and 0.60 MPa or less at −20 ° C. A sheet satisfying the acceptance criteria has a clear difference in flexibility when touched by hand, as compared with a sheet not satisfying the acceptance criteria. In addition, the case where the volatilization loss was 7% or less was regarded as acceptable.

As is clear from the results in Table 1, the molded sheet obtained from the composition of the present invention had good flexibility, low volatility, and no bleed-out of the plasticizer was observed. .

On the other hand, the tributyl acetyl citrate of Comparative Example 1 has good flexibility but high volatility.
Bleed out was also recognized. PEG # 30 of Comparative Example 2
0 Dioctate has good flexibility and low volatility,
Marked bleed-out was observed. The dipropylene glycol dibenzoate of Comparative Example 3 had no bleed-out, but had a slightly high volatility and low flexibility. The diethylene glycol dibenzoate of Comparative Example 4 does not show bleed-out, but has high volatility.
It was inflexible.

[0098]

As described above, the plasticizer for lactic acid-based polymers of the present invention comprising dibenzoate of polyethylene glycol having a number average molecular weight of 150 or more has a low volatility and has a high flexibility for lactic acid-based polymer moldings. Moreover, the tendency to bleed out is low.

The lactic acid-based polymer composition of the present invention obtained by adding the above-mentioned plasticizer of the present invention to a lactic acid-based polymer has excellent stability over time under ordinary use conditions, and is a constituent component of the composition. The strength or flexibility of the obtained molded product can be controlled by changing the compounding ratio of.

A molded product obtained by molding the lactic acid-based polymer composition of the present invention has a small amount of volatilization loss in the plasticizer of the present invention, excellent flexibility, and bleed-out of the plasticizer under ordinary conditions. Absent. Therefore, the molded article of the present invention has excellent stability over time under ordinary conditions. Moreover, the molded product of the present invention can be made into a form of a flexible sheet, and can be used as a soft material such as a packaging material and various molded products which require flexibility. On the other hand, when the molded article of the present invention is discarded,
It has good biodegradability, especially excellent in decomposability in compost, and can be decomposed until the outer shape is not maintained in 3 to 6 months.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Kamogawa             13 Yakura-cho, Yashimajima, Fushimi-ku, Kyoto-shi, Kyoto New             Within Nippon Rika Co., Ltd. (72) Inventor Kazuhiro Hattori             13 Yakura-cho, Yashimajima, Fushimi-ku, Kyoto-shi, Kyoto New             Within Nippon Rika Co., Ltd. (72) Inventor Eiichi Kobayashi             Osaka Prefecture Kita-ku Umeda 1-12-39 Stock Association             Inside the company Kuraray F-term (reference) 4F071 AA43 AA51 AC06 AE04 AF52                       AF53 AH05                 4J002 CF181 CH022 ED036 FD022                       FD026 GT00

Claims (8)

[Claims] 1. A plasticizer for a lactic acid-based polymer, which comprises dibenzoate of polyethylene glycol having a number average molecular weight of 150 or more. 2. The plasticizer for a lactic acid-based polymer according to claim 1, wherein the polyethylene glycol has a number average molecular weight of 150 to 5,000. 3. A lactic acid-based polymer composition containing a lactic acid-based polymer and a plasticizer for a lactic acid-based polymer, which comprises dibenzoate of polyethylene glycol having a number average molecular weight of 150 or more. 4. The lactic acid-based polymer composition according to claim 3, wherein the polyethylene glycol has a number average molecular weight of 150 to 5,000. 5. The lactic acid-based polymer composition according to claim 3, wherein the lactic acid-based polymer has a weight average molecular weight of 50,000 or more. 6. Based on 100 parts by weight of the lactic acid-based polymer,
The lactic acid-based polymer composition according to any one of claims 3 to 5, which contains 1 to 300 parts by weight of a plasticizer for a lactic acid-based polymer. 7. A molded product obtained by molding the lactic acid-based polymer composition according to any one of claims 3 to 6. 8. The method of claim 7 in the form of a sheet or film.
The molded article according to.