JP3256350B2 - Lactic acid based polymer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lactic acid-based polymer composition having improved weather resistance. More specifically, the present invention relates to a lactic acid-based polymer composition such as a polylactic acid and a lactic acid-hydroxycarboxylic acid copolymer having an improved weather resistance containing an ultraviolet absorber, a light stabilizer and the like.

[0002]

2. Description of the Related Art Hitherto, polylactic acid has been widely known as a hydrolyzable polymer. Particularly when applied to the body, lactic acid produced by hydrolysis is non-toxic, and carbon dioxide and water are metabolized. And are safely discharged outside the body, so that various applications for medical use are expected. For example, Japanese Patent Publication No. 41-2734 discloses a bioabsorbable surgical suture composed of a filament of polylactic acid.
No. 55 discloses an osteosynthesis pin formed by molding polylactic acid.

[0003] The hydrolysis rate of polylactic acid depends on its crystallinity and molecular weight. L-lactic acid and D-lactic acid are present in lactic acid, and poly (L-lactic acid) or poly (D-lactic acid) whose structural unit consists only of L-form or only D-form is a crystalline polymer. And poly (DL-) in which structural units of L-form and D-form are mixed in comparison with a low hydrolysis rate.
Lactic acid) has a high hydrolysis rate.

In order to improve the hydrolyzability and mechanical properties of polylactic acid, copolymers of lactic acid with various hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid have been disclosed. For example,
JP-A-9-36597 discloses that 65 to 85% by weight of lactic acid units
A surgical aid comprising a lactic acid-glycolic acid copolymer composed of glycerol and 35 to 15% by weight of glycolic acid units is disclosed. Japanese Patent Application Publication No. 62-501611 discloses caprolactone and lactide. A medical implant comprising a copolymer with (a cyclic dimer of lactic acid) is disclosed.

[0005] Since polylactic acid or lactic acid-hydroxycarboxylic acid copolymer is effectively hydrolyzed even by moisture in the air, it has recently been applied as a basic raw material of degradable general-purpose materials for disposable uses other than medical uses as described above. Is considered.

There are various findings regarding the hydrolysis rate of polylactic acid and lactic acid-hydroxycarboxylic acid copolymer.
Therefore, when making a disposable decomposable material using these resins, it is relatively easy to design the material in accordance with the decomposition time required for the application. For example,
If the period of use is about six months, high molecular weight poly (L
(Lactic acid) is preferable, and the use period is about several days, and it is preferable to use the lactic acid-glycolic acid copolymer for the purpose of decomposing as quickly as possible after use.

[0007]

However, according to the knowledge of the present inventors, when a resin molded product made from a lactic acid-based polymer such as polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer is used outdoors, the resin molded product cannot be used indoors. It was found that the strength decreased clearly earlier than when used in a dark place or in a living body, and phenomena such as embrittlement, destruction, and disappearance occurred earlier than expected.

For example, according to the knowledge of the rate of hydrolysis, a film made in the hope of maintaining its strength for at least half a year at a normal temperature was used outdoors. It no longer fulfills its function. To make matters worse,
The extent to which this degradation rate was enhanced was completely unpredictable, and the duration of the degradation varied.

As described above, in order to decompose faster than expected when used outdoors, it is necessary to use lactic acid-based polymers such as polylactic acid and lactic acid-hydroxycarboxylic acid copolymer as degradable resin molded material. And sometimes it can be serious, a major drawback that can never be overlooked.

[0010] It is an object of the present invention to solve the above problems and to provide a lactic acid-based polymer composition excellent in weather resistance in which premature decomposition outdoors is suppressed.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, by adding a specific amount of an ultraviolet absorber or a light stabilizer to a lactic acid-based polymer, the lactic acid-based polymer was decomposed too early in the outdoors. Have been found to be able to be effectively suppressed, and the present invention has been completed.

That is, the present invention provides a lactic acid-based polymer 10
A lactic acid-based polymer composition comprising 0.001 to 5 parts by weight of at least one additive selected from an ultraviolet absorber and a light stabilizer with respect to 0 parts by weight.

The lactic acid-based polymer composition of the present invention can be obtained by adding and mixing an ultraviolet absorber or a light stabilizer to a lactic acid-based polymer such as polylactic acid or lactic acid-hydroxycarboxylic acid copolymer. The lactic acid-based polymer composition of the present invention is excellent in weather resistance and, furthermore, maintains the inherent hydrolyzability of the lactic acid-based polymer, so that a molded article obtained therefrom can be used outdoors or indoors or in the dark. It shows the same decomposition behavior as when used in places. Therefore, it is useful mainly as a material for molded articles used outdoors.

Hereinafter, the present invention will be described in detail. In the present invention, the lactic acid-based polymer refers to polylactic acid and lactic acid-hydroxycarboxylic acid copolymer. Lactic acid has an L-form and a D-form. In the present invention, lactic acid is simply referred to as lactic acid, and unless otherwise specified, L-form is used.
It refers to both body and D-body. Further, the molecular weight of the polymer refers to the weight average molecular weight unless otherwise specified.

The lactic acid-based polymer used in the present invention is a copolymer of polylactic acid and another hydroxycarboxylic acid copolymerizable with lactic acid, and a copolymer preferably used is a copolymer of lactic acid or lactide and a hydroxycarboxylic acid. It is.

The polylactic acid used in the present invention includes a poly (L-lactic acid) whose structural unit is composed of only L-lactic acid, a poly (D-lactic acid) composed of only D-lactic acid, and a polylactic acid unit composed of L-lactic acid and D-lactic acid. Lactic acid units and poly (DL-)
Lactic acid) can be used. Examples of the hydroxycarboxylic acid which is a comonomer of the lactic acid-hydroxycarboxylic acid copolymer used in the present invention include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, and hydroxyheptanoic acid.

Lactic acid polymers such as polylactic acid and lactic acid-hydroxycarboxylic acid copolymer used in the present invention are L
-It can be obtained by selecting a required one from lactic acid, D-lactic acid and hydroxycarboxylic acid as a raw material monomer and performing dehydration polycondensation. Examples of the method of dehydration polycondensation include a method of performing a heat dehydration condensation reaction of lactic acid or lactic acid and other hydroxycarboxylic acids, preferably in an organic solvent, and while removing generated water out of the reaction system. It can also be obtained by ring-opening polymerization of cyclic esters such as lactide, which is a cyclic dimer of lactic acid, and glycolide, caprolactone, propiolactone, butyrolactone, and valerolactone, which are cyclic dimers of glycolic acid. .

The molded product obtained from the lactic acid-based polymer is hydrolyzed after disposal by water or rainwater in the air, not only in water or soil, but also during use. Therefore, the molecular weight of the lactic acid-based polymer is related to properties such as tensile strength of molded products such as films and sheets, and the lower the molecular weight, the lower the tensile strength, and the higher the molecular weight, the higher the tensile strength. But,
If it is too high, molding processability tends to decrease, and molding tends to be difficult. From such a viewpoint, the molecular weight of the lactic acid-based polymer used in the present invention is preferably in the range of 10,000 to 1,000,000. More preferably, 30,0
00 to 500,000.

When the lactic acid-based polymer is polylactic acid, a sheet, film or other molded product is molded by melt extrusion molding, calender molding, injection molding or the like, and is vacuum-formed, air-pressure formed or vacuum-pressure formed under heating. If heat treatment such as heat setting is performed, crystallization may proceed in some cases and the transparency of the molded product may be lost. In particular,
100 mol% poly (L-lactic acid) and L
-In the case of poly (D-lactic acid) having 100 mol% of lactic acid units, in order to obtain a transparent molded product, the above-mentioned vacuum molding, air pressure molding or vacuum pressure molding, or heat treatment such as heat fixing is performed. It is necessary to perform the process at a low temperature of about 60 to 90 ° C., and there is a drawback that the temperature range of forming processing is narrow.

In view of the above, in order to obtain a transparent molded product, poly (L-lactic acid) comprising only L-lactic acid units or poly (D-lactic acid) comprising only D-lactic acid units is more preferable than poly (D-lactic acid). -Poly (DL-lactic acid) comprising lactic acid units and D-lactic acid units is preferred. Specifically, the polylactic acid preferably used has a weight average molecular weight of 30,000.
~ 500,000, and the L-lactic acid unit is 50 ~
100 mol% (more preferably 70 to 100 mol%)
Poly (D-lactic acid) and poly (DL-lactic acid) having 50-100 mol% (more preferably 70-100 mol%) of D-lactic acid units. ).

When the lactic acid-based polymer is a lactic acid-hydroxycarboxylic acid copolymer, the degradability is affected by the content of lactic acid units. When the content of the lactic acid unit is small, the decomposition may be extremely slow or insufficient when the product is discarded after use. From such a viewpoint, the content of the lactic acid unit in the copolymer is preferably 10 mol% or more.

Specifically, a preferred lactic acid-glycolic acid copolymer has a weight average molecular weight of 30,000 to 50.
000 and a copolymer having 30 to 98 mol% of lactic acid units and 2 to 70 mol% of glycolic acid units. A more preferred composition is 70-98 mol% of lactic acid units.
And a copolymer having 2 to 30 mol% of glycolic acid units. A preferred lactic acid-hydroxycaproic acid copolymer has a weight average molecular weight of 30,000 to 50.
000 and is a copolymer having 10-98 mol% of lactic acid units and 2-90 mol% of hydroxycaproic acid units. More preferred compositions are lactic acid units 20-9
A copolymer having 8 mol% and 2-80 mol% of hydroxycaproic acid units.

The optimum molecular weight and copolymer composition of the lactic acid-based polymer used in the present invention are appropriately selected from the above ranges in accordance with the longest sticking period in the intended use. For example, based on the findings of the present inventors, when the use period is six months or more, it is preferable to use poly (L-lactic acid) having a molecular weight of 150,000 or more. For example, when the use period is about one month, poly (L-lactic acid) having a molecular weight of 50,000 or more or poly (DL-lactic acid) having a molecular weight of 100,000 or more and containing less than 5 mol% of D-lactic acid units ) Is preferably used. When the use period is only a few days to a few weeks, in addition to the above-mentioned polymer, poly (DL-lactic acid) containing less than 25 mol% of D-lactic acid units or lactic acid-glycolic acid containing less than 15 mol% of glycolic acid units Copolymers are preferably used. When a molded product having high flexibility is required, for example, a molded product suitable for use for about 3 months can be obtained by using a lactic acid-hydroxycaproic acid copolymer containing about 60 mol% of hydroxycaproic acid units. Can be

The lactic acid-based polymer composition of the present invention comprises a lactic acid-based polymer 10 obtained by ring-opening polymerization or dehydration polycondensation.
0.001 to 5 parts by weight of at least one additive selected from an ultraviolet absorber and a light stabilizer with respect to 0 parts by weight,
More preferably, it is obtained by adding and mixing 0.05 to 5 parts by weight. When the added amount of the ultraviolet absorber and the light stabilizer is small, the weather resistance when the molded article is used outdoors, that is, the effect of suppressing the promotion of decomposition due to exposure to ultraviolet light or the like is not sufficiently recognized, or is too large. And the lactic acid-based polymer tends to lose its inherent properties. In consideration of this, it is preferable that the addition amounts of the ultraviolet absorber and the light stabilizer are within the above ranges.

The ultraviolet absorber absorbs ultraviolet light having a destructive high energy in the wavelength range of 250 to 380 nm, changes the wavelength to a nondestructive wavelength, and re-emits the light. It does not absorb ultraviolet light,
Photodegradation of a material is suppressed by some mechanism, such as non-radical decomposition of hydroperoxide, which is a photodegradation initiator, and capture and removal of radicals generated by photodecomposition. The distinction between UV absorbers and light stabilizers may not always be clear.

The ultraviolet absorber and light stabilizer used in the present invention include phenyl salicylate, p-tert-
Salicylic acid derivatives such as butylphenyl salicylate,

2,4-dihydroxybenzophenone, 2
-Hydroxy-4-methoxybenzophenone, 2,2 '
-Dihydroxy-4-methoxybenzophenone, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2 ', 4,4'-tetra Benzophenones such as hydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane;

2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'- Hydroxy-3'-ter
t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-ter
t-octylphenyl) benzotriazole, 2-
(2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- [2'-hydroxy-3'-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2'-methylenebis [4- (1,
1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like.

Trade name SanduvorEPU and Sand
oxalic anilide derivatives known as uvorVSU and the like, 2-
Ethoxy-5-tert-butyl-2'-ethyl oxalic acid bisanilide, 2-ethoxy-2-ethyl oxalic acid bisanilide, 2,4-di-tert-butylphenyl-3,5-
Di-tert-butyl-4-hydroxybenzoate,
2-ethylhexyl-2-cyano-3,3-diphenylacrylate, 1,3-bis- (4-benzoyl-3-
(Hydroxyphenoxy) -2-propyl acrylate,
1,3-bis- (4-benzoyl-3-hydroxyphenoxy) -2-propyl methacrylate, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, methyl ortho-benzoylbenzoate, ethyl-2-cyano-3 , 3-diphenyl acrylate, 2-hydroxy-
Known as 4-benzyloxybenzophenone, nickel dibutyldithiocarbamate, nickel / titobisphenol complex, nickel-containing organic light stabilizer, barium, sodium, phosphorus-containing organic / inorganic complex, semicarbazone light stabilizer, trade name Sanshade, etc. Zinc oxide UV stabilizers and synergists

Bis (2,2,6,6-tetramethyl-4
-Piperidyl) sebacate, bis (1,2,2,6,6)
-Pentamethyl-4-piperidyl) sebacate, 1-
[2- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4
-{3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6
-Tetramethylpiperidine, 8-benzyl-7,7,
9,9-tetramethyl-3-octyl-1,2,3-triazaspiro [4,5] undecane-2,4-dione;
4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate polycondensate,

Poly [6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-
Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-
Tetramethyl-4-piperidyl) imino]], 2-
Bis (1,2,2,2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate
6,6-pentamethyl-4-piperidyl), tetraxy (2,2,6,6-tetramethyl-4-piperidyl)
1,2,3,4-butanetetracarboxylate, 1,
2,3,4-butanetetracarboxylic acid and 1,2,2
Condensate of 6,6-pentamethyl-4-piperidinol with tridecyl alcohol, 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and tridecyl alcohol Condensate of 1,
2,3,4-butanetetracarboxylic acid and 1,2,2
6,6-pentamethyl-4-piperidinol and β, β,
β ′, β′-tetramethyl-3,9- (2,4,8,1
Condensate with 0-tetraoxaspiro [5,5] undecane) diethanol, 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and β, β, β ', β'-tetramethyl-3,9-
Condensate with (2,4,8,10-tetraoxaspiro [5,5] undecane) diethanol;

1,2,2,6,6-pentamethyl-4-
Hindered amines such as piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate are exemplified.

It should be noted that 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, which is known as an ultraviolet absorber for water-based paints, promotes unpredictable decomposition in outdoor use which is the object of the present invention. Is small and is not suitable for the present invention.

Further, [2,2'-thiobis-] which is known as a light stabilizer such as polyethylene and polypropylene
(4-tert-octylphenolite)]-n-butylamine nickel or [2,2′-thiobis- (4-te
rt-octylphenolite)]-2-ethylhexylamine nickel, when mixed with polylactic acid and a lactic acid-hydroxycarboxylic acid copolymer, may cause decomposition of the polylactic acid and the lactic acid-hydroxycarboxylic acid copolymer. Is not suitable.

As a method for producing a lactic acid-based polymer composition by mixing an ultraviolet absorber and / or a light stabilizer with a lactic acid-based polymer, a predetermined amount of an ultraviolet absorber and / or a light stabilizer is added to the lactic acid-based polymer. And mixing at a temperature near room temperature using a mixer such as a ribbon blender or a Henschel mixer.
A method of heating and melting at 280 ° C., adding and kneading a predetermined amount of an ultraviolet absorber and / or a light stabilizer, or using a lactic acid-based polymer and an ultraviolet absorber and / or a light stabilizer in chloroform, methylene chloride, benzene, toluene , Xylene, dimethylformamide, dimethylsulfoxide,
Examples thereof include a method of dissolving and mixing in a solvent such as dimethylimidazolidinone.

The lactic acid-based polymer composition of the present invention contains, if necessary, other additives such as a plasticizer, an antioxidant, a heat stabilizer, a lubricant, a pigment, and a coloring agent in addition to the above-mentioned ultraviolet absorber and stabilizer. It can be mixed.

Phthalic acid derivatives such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, diisodecyl phthalate, ditridecyl phthalate and diundecyl phthalate;
Isophthalic acid derivatives such as diisooctyl phthalate; adipic acid derivatives such as di-n-butyl adipate and dioctyl adipate; maleic acid derivatives such as di-n-butyl maleate; citric acid derivatives such as tri-n-butyl citrate; Itaconic acid derivatives such as butyl itaconate,
Oleic acid derivatives such as butyl oleate, ricinoleic acid derivatives such as glycerin monoricinoleate, low molecular weight compounds such as phosphate esters such as tricresyl phosphate and trixylenyl phosphate, and high molecular weight plastics such as polyethylene adipate and polyacrylate Agents and the like. Among the above plasticizers, preferred plasticizers include glycerin triacetate (triacetin), lactic acid, lactide, lactic acid oligomers having a degree of polymerization of about 2 to 10, and the like.

When a plasticizer is added to the lactic acid-based polymer composition, the amount added is appropriately selected according to the degree of flexibility required for the molded product. If too much is added, it is not preferable because it bleeds out (embosses to the surface) on the surface of the molded article. Therefore, the added amount of the plasticizer is 100
The amount is preferably from 1 to 50 parts by weight, more preferably from 5 to 20 parts by weight based on parts by weight. When a plasticizer is contained in the lactic acid-based polymer, it is preferable that the polymer has low crystallinity in terms of plasticization efficiency, prevention of bleed-out, and the like. Therefore, when including a plasticizer in the lactic acid-based polymer composition,
It is preferable to use poly (DL-lactic acid) or lactic acid-hydroxy acid copolymer as the lactic acid-based polymer. More preferably, the content of L-lactic acid unit is 50 to 98 mol% and D
Poly (DL-lactic acid) having 2 to 50 mol% of lactic acid units, poly (DL-lactic acid) having 50 to 98 mol% of D-lactic acid units and 2 to 50 mol% of L-lactic acid units, Lactic acid-glycolic acid copolymer having 2-70 mol% of glycolic acid units and 30-98 mol% of lactic acid units, 2-90 mol% of hydroxycaproic acid units and 10-98 of lactic acid units
Lactic acid-hydroxycaproic acid copolymer having a mole% is used. These polymers are effectively plasticized by the plasticizer and can prevent bleed-out of the plasticizer.

[0039]

The present invention will be described below in further detail with reference to examples. Preparation Examples 1 to 9 <Preparation of lactic acid-based polymer by ring-opening polymerization> Commercially available L-lactide (hereinafter, referred to as L-LTD), DL-lactide (50 mol of D-form / 50 mol of L-form, hereinafter, DL- LT
D), and glycolide (hereinafter, GLD)
Was purified by recrystallization four times using ethyl acetate. Commercially available ε-caprolactone (hereinafter referred to as CL) was dried over calcium hydride and then purified by distillation.
In a glass-made reaction vessel whose surface was treated with silane, L-LTD and DL-LT in the amounts shown in [Table 1] and [Table 2] were added.
D, GLD, CL, stannous octoate as a catalyst and lauryl alcohol (Preparation Examples 1 and 2) as a molecular weight regulator were charged, and the inside of the vessel was degassed under reduced pressure and dried overnight. The reaction vessel was sealed under reduced pressure, heated to the temperature shown in [Table 1] and [Table 2], and polymerized for a predetermined time. After the completion of the reaction, the content in the reaction vessel was dissolved in 20 times the volume of chloroform, and further poured into 5 times the volume of hexane. The precipitated polymer was recovered and dried to obtain lactic acid-based polymers P-1 to P-9. The molecular weight of the obtained lactic acid-based polymer can be determined by gel permeation chromatography using chloroform as a solvent (hereinafter referred to as G
PC) and calculated in terms of polystyrene. [Table 1] and [Table 2] show polymerization conditions and measurement results of molecular weights of the obtained various lactic acid-based polymers.

[0040]

[Table 1]

[0041]

[Table 2]

Preparation Examples 10 to 13 <Preparation of lactic acid-based polymer by direct dehydration polycondensation>
n Stark Trap was placed in a reactor equipped with commercially available 90% L-lactic acid (hereinafter referred to as LA), 90% D-lactic acid (hereinafter referred to as DA), and glycolic acid (hereinafter referred to as GA) in the amounts shown in Table 3. ) And hydroxycaproic acid (hereinafter referred to as HCA).
After distilling water while stirring at 50 mmHg for 3 hours,
6.2 g of tin powder was added, and the mixture was further stirred at 150 ° C. and 30 mmHg for 2 hours to be oligomerized. To this oligomer were added 28.8 g of tin powder and 21.1 kg of diphenyl ether, and an azeotropic dehydration reaction was carried out at 150 ° C. and 35 mmHg. The distilled water and the solvent were separated by a water separator, and only the solvent was returned to the reactor. . After 2 hours, 4.6 g of organic solvent was returned to the reactor.
kg of molecular sieve 3A, and then returned to the reactor at 150 ° C. and 35 mmHg.
For 40 hours to obtain a polylactic acid solution. The solution was diluted by adding 44 kg of dehydrated diphenyl ether, cooled to 40 ° C., and the precipitated crystals were filtered.
kg n-hexane for 3 times, 60 ° C., 50 mmH
g. 0.5N-HCl 12.0k
g and 12.0 kg of ethanol, stirred at 35 ° C. for 1 hour, filtered, dried at 60 ° C. and 50 mmHg, and the powder of lactic acid-based polymer P-10 to P-13 was obtained at a yield of about 85%.
I got The obtained P-10 to P-13 were dissolved in chloroform, and the molecular weight in terms of polystyrene was measured by GPC (gel permeation chromatography).
Similarly, P-10 was dissolved in acetonitrile and HL
The content of the residual monomer in the polymer was 0.2% by weight as measured by the C (high performance liquid chromatography) method.
Met. [Table 3] shows the polymerization conditions and the results of the molecular weight measurements of the obtained various lactic acid-based polymers.

[0043]

[Table 3]

Preparation Example 14 <Preparation of plasticizer> L-lactide 1.8k put in a reactor
g of lactic acid aqueous solution (concentration: 87% by weight)
Heated at 100 ° C. for 2 hours. Upon cooling, a viscous transparent liquid was obtained at room temperature. The oligomer was dissolved in chloroform, and the degree of polymerization distribution was measured by gel permeation chromatography. As a result, lactic acid and lactic acid oligomer were contained. Average degree of polymerization is 2.8
Met. Hereinafter, it is referred to as LA oligomer.

Examples 1 to 7, Comparative Examples 1 to 10 Each of P-1, P-4 and P-5 obtained in the preparation examples was dissolved in chloroform (concentration: 10% by weight), to which [Table 4] , [Table 7] or [Table 8]
(2′-hydroxy-5′-methylphenyl) benzotriazole (hereinafter referred to as TP), 2-hydroxy-4
-N-Octoxybenzophenone (hereinafter, referred to as HOB) or 4-dodecyloxy-2-hydroxybenzophenone (hereinafter, referred to as DHB) was added and mixed well to obtain a solution of a lactic acid-based polymer composition containing an ultraviolet absorber. The solution was cast on a glass surface and air-dried, and then the solvent was completely removed by drying under reduced pressure to obtain a transparent film having a thickness of 100 μm. In addition, P-2 and P obtained in Preparation Examples
-3 using a Brabender Plast Bluff type kneader
While melting at 20 ° C, a predetermined amount of bis (2,2,6,6-tetramethyl-4-) shown in [Table 5] or [Table 6] was obtained.
Piperidyl) sebacate (hereinafter referred to as HAL), TP
Or 2- (2'-hydroxy-3 ', 5'-di-te
rt-butylphenyl) benzotriazole (hereinafter referred to as T
320) was added and mixed to obtain a lactic acid-based polymer composition containing an ultraviolet absorber. The obtained polymer composition was treated at a temperature shown in [Table 5] or [Table 6] at 50 kg / cm ^2.
To produce a transparent sheet having a thickness of 0.5 mm.

In Examples 1 to 3 and Comparative Example 1, the film was fixed and left in a place where it was frequently outdoors (hereinafter, this condition is simply referred to as outdoors). In Comparative Example 2, it was also placed inside a box covered outdoors (rain was allowed to enter) so that the sun did not shine (this condition is simply referred to as a dark place). On days 24 and 44, a part of the film was taken and the molecular weight was measured by GPC. The decomposition of the polymer composition to which TP was added (Examples 1 to 3) was clearly suppressed as compared to the product left outdoors without adding TP (Comparative Example 1). In particular, in Examples 2 and 3, The decomposition behavior was almost the same as that in the dark place (Comparative Example 2).
The results obtained are shown in [Table 4].

[0047]

[Table 4] In Example 4 and Comparative Example 3, as in Example 1, outdoors.
In Comparative Example 4, similarly to Comparative Example 2, each sheet was left in a dark place, and a tensile strength test was performed on the sheet after a lapse of a predetermined number of days. The results obtained are shown in [Table 5].

[0048]

[Table 5] In Example 5 and Comparative Example 5, each sheet was left outdoors, and in Comparative Example 6, the sheet was left in a dark place and subjected to a tensile strength test after a lapse of a predetermined number of days. The results obtained are shown in [Table 6].

[0049]

[Table 6] In Example 6 and Comparative Example 7, the film was left outdoors. In Comparative Example 8, it was left in a dark place. Three months later, a part of the film was taken and its molecular weight was measured by GPC. The results obtained are shown in [Table 7].

[0050]

[Table 7] In Example 7 and Comparative Example 9, the film was left outdoors. In Comparative Example 10, it was left in a dark place. Two months later, a part of the film was taken and the molecular weight was measured by GPC. The results obtained are shown in [Table 8].

[0051]

[Table 8]

Examples 8 to 11 The ultraviolet absorbers shown in Table 9 were added to P-10 to P-13 obtained in the preparation examples, and mixed at room temperature using a Henschel mixer to contain the ultraviolet absorbers. A lactic acid-based resin composition was obtained. Next, triacetin was added as a plasticizer to the lactic acid-based resin composition obtained from P-10 and P-11 in the amount shown in [Table 9].
The mixture was mixed at 0 ° C. to obtain a lactic acid-based resin composition containing an ultraviolet absorber and a plasticizer. The obtained lactic acid-based resin composition was pelletized using a twin-screw extruder, and then melt-extruded using a single-screw extruder to obtain a film having a thickness of 150 μm. Degradability of the obtained film was evaluated in the same manner as in Example 7. However, the leaving period in Examples 10 to 11 was one month. The formulation, extrusion temperature and molecular weight change are shown in [Table 9].

[0053]

[Table 9]

Examples 12 to 16 To the lactic acid-based polymers P-5 to P-9 obtained in the preparation examples, an ultraviolet absorbent shown in Table 10 was added and mixed at room temperature using a Henschel mixer to absorb ultraviolet light. A lactic acid-based polymer composition containing the agent was obtained. Next, triacetin was used as a plasticizer in the composition obtained from P-7 and P-8, and the LA oligomer obtained in Preparation Example 6 was used as a plasticizer in the composition obtained from P-9. After addition at the indicated ratio, P-7 and P-8 were 150 ° C., and P-9 was 130 ° C.
And mixed using a plastmill. Furthermore, these are
-6 is 210 ° C, P-7 and P-8 are 150 ° C, P-
9 is 130 ℃, P-5 is 100 ℃ and pressure is 50kg
/ Cm ² and processed into a sheet having a thickness of 1 mm. Next, these sheet materials were cooled using liquid nitrogen and pulverized using a hammer mill pulverizer to obtain a lactic acid-based polymer composition. Then, it was extruded with a single screw extruder from a T-die at the temperature shown in [Table 10],
10-120 μm lactic acid-based polymer films F-1 to F
-5 was obtained. The formulation, extrusion temperature and film thickness are shown in [Table 10]. Obtained lactic acid-based polymer film F
-1 to F-5 were buried in the soil at a depth of 20 cm and taken out 12 months later, and the molecular weight retention was evaluated by the following method. The results obtained are shown in [Table 10].

<Molecular Weight Retention> A lactic acid-based polymer film left in the soil for 12 months was dissolved in chloroform,
The molecular weight in terms of polystyrene is measured by the PC method, the difference from the molecular weight immediately before production is calculated, and the difference is determined by the following equation. DW = 100 W ₁ / W _{0 In the} above formula, DW: molecular weight retention W ₀ : molecular weight immediately before production W ₁ : molecular weight after use and standing in soil for 12 months Further, lactic acid obtained in Example 13 The tensile breaking strength of the system polymer film F-2 was measured at a tensile speed of 50 cm / min using a tensile tester. As a result, the tensile strength at break was 4.6 kgf / mm ² . Also, F-2 is 2
Tensile rupture strength after standing at 3 ° C. for 21 days is 2.
It was 4 kgf / mm ² .

Comparative Example 11 100 parts by weight of polyvinyl chloride (average degree of polymerization: 1100)
Resin composition containing 35 parts by weight of dioctyl phthalate, 2 parts by weight of a composite stabilizer, 1.0 part by weight of TP as an ultraviolet absorber and 1 part by weight of a complex fatty acid amide (stearic acid: palmitic acid amide, 7: 3 weight ratio) Was kneaded and rolled by a calender method to obtain a soft vinyl chloride film having a thickness of 100 μm. The obtained soft vinyl chloride film was buried in the soil for 12 months in the same manner as in Example 12, then dissolved in tetrahydrofuran, and the molecular weight retention was evaluated by GPC in the same manner as in Example 12 to obtain a film. The results are shown in [Table 10].

[0057]

[Table 10]

[0058]

The lactic acid-based polymer composition of the present invention provides a molded article having excellent weather resistance. In addition, the lactic acid-based polymer composition of the present invention maintains the original hydrolyzability of the lactic acid-based polymer, so that a molded product obtained from the composition is subjected to a natural environment when discarded after use. Does not decompose and accumulate as waste.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References WO 90/1521 (WO, A1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C08L 67/04

Claims (7)

(57) [Claims] 1. A lactic acid-based polymer composition comprising 0.001 to 5 parts by weight of at least one additive selected from an ultraviolet absorber and a light stabilizer based on 100 parts by weight of a lactic acid-based polymer. 2. The method according to claim 1, wherein the additives are 2-hydroxy-4-n-octoxybenzophenone and 4-dodecyloquin-2-ene.
Benzophenones including hydroxybenzophenone, 2
-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ',
Benzotriazoles, including 5′-di-tert-butylphenyl) benzotriazole, and bis (2,
The lactic acid-based polymer composition according to claim 1, which is at least one additive selected from sebacates including (2,6,6-tetramethyl-4-piperidyl) sebacate. 3. The lactic acid-based polymer composition according to claim 1, wherein the lactic acid-based polymer is at least one polymer selected from polylactic acid and a lactic acid-hydroxycarboxylic acid copolymer. 4. A lactic acid-based polymer having a molecular weight of 30,000
4. The lactic acid-based polymer composition according to claim 1, wherein the lactic acid-based polymer composition has a molecular weight of about 500,000. 5. The polylactic acid is an L-lactic acid unit of 50 to 100.
Poly (L-lactic acid), poly (DL-lactic acid),
5. The lactic acid-based polymer composition according to claim 4, wherein the polymer is at least one polymer selected from poly (D-lactic acid) and poly (DL-lactic acid) having 50 to 100 mol% of D-lactic acid units. object. 6. A lactic acid-hydroxycarboxylic acid copolymer comprising 30 to 98% by mole of lactic acid units and 2 to 2 glycolic acid units.
At least one polymer selected from lactic acid-glycolic acid copolymer having 70 mol% and lactic acid-hydroxycaproic acid copolymer having 10-98 mol% of lactic acid units and 2-90 mol% of hydroxycaproic acid units. The lactic acid-based polymer composition according to claim 4, characterized in that: 7. The lactic acid-based polymer composition is prepared by adding 1 to 50 parts by weight of at least one plasticizer selected from glycerin triacetate, lactic acid, a lactic acid oligomer having a polymerization degree of 2 to 10 and lactide to 100 parts by weight of the lactic acid-based polymer. The lactic acid-based polymer composition according to claim 1, wherein the composition comprises parts by weight.