JP3359764B2 - Heat-resistant lactic acid-based polymer molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant lactic acid-based polymer molded product. More specifically, the present invention relates to a heat-resistant lactic acid-based polymer molded article having excellent heat resistance and impact resistance and decomposing in a natural environment after use.

[0002]

2. Description of the Related Art Generally, resins such as polypropylene and crystalline polyethylene terephthalate (hereinafter abbreviated as PET) are used as raw materials for containers having excellent heat resistance and impact resistance. Further, since PET has a disadvantage that crystallization is slow and a molding cycle requires a long time, this disadvantage is overcome by increasing the mold temperature or using a crystallization nucleating agent.

[0003] However, molded articles produced from such resins are excellent in heat resistance. However, when discarded, they increase the amount of dust and are hardly decomposed in the natural environment. Also remain semi-permanently in the ground. In addition, abandoned plastics cause problems such as degrading the landscape and destroying the living environment of marine life.

On the other hand, polylactic acid or a copolymer of lactic acid and another hydroxycarboxylic acid (hereinafter abbreviated as a lactic acid-based polymer) has been developed as a thermoplastic resin having biodegradability. These polymers are 100% biodegradable within the animal's body within months to a year, and when placed in soil or seawater, begin to degrade in a few weeks in a humid environment, from about one year to several years. Decomposes in a year, and the decomposition products have the property of becoming lactic acid, carbon dioxide, and water that are harmless to the human body. Lactic acid, which is a raw material of the lactic acid-based polymer, is produced by fermentation or chemical synthesis. In particular, L-lactic acid produced by fermentation has been produced in large quantities and has become inexpensive. Because of its high rigidity, use of various polymers having a high L-lactic acid content is expected at present.

A container formed by injection molding of a lactic acid-based polymer or the like is excellent in rigidity, but has low heat resistance or low heat resistance and impact resistance. For example, hot water or a microwave oven can be used in a packaging container. Use is limited.
In order to have heat resistance, it is necessary to cool the mold for a long time during the molding process, or it is necessary to anneal the molded article after the molding to highly crystallize. However, a long cooling step during molding is not practical, and crystallization tends to be insufficient,
In addition, post-crystallization by annealing has a disadvantage that the molded article is easily deformed in the course of crystallization.

As a method for increasing the crystallization speed, Japanese Patent Application Laid-Open No. 60-86156 discloses a wholly aromatic polyester containing terephthalic acid and resorcin as main crystallization nucleating agents in order to promote crystallization of PET. As described for adding a fine powder, a method of adding a nucleating agent for promoting crystallization is known.

On the other hand, an example of adding such an additive to a polymer having biodegradability is disclosed in Japanese Patent Application Laid-Open No. 5-706.
No. 96, Japanese Translation of PCT International Publication No. 4-5047731, USP
JP-A-5-180765, JP-A-6-504799, and JP-A-4-220456. Japanese Patent Application Laid-Open No. 5-70696 discloses that, as a material for a plastic container, a biodegradable plastic such as poly-3-hydroxybutyrate / poly-3-hydroxyvalerate copolymer, polycaprolactone or polylactic acid is used. It is disclosed that calcium carbonate having a diameter of 20 μ or less and hydrous magnesium silicate (talc) are mixed in a weight ratio of 10 to 40%. However, this technique is intended to promote the decomposition of the biodegradable plastic after disposal by adding a large amount of an inorganic filler, but does not improve the heat resistance by crystallizing the polymer. In addition, Japanese Patent Publication No. 4-5047
No. 31 (WO 90/01521) describes that the properties of hardness, strength and temperature resistance can be changed by adding a filler of an inorganic compound such as silica or kaolinite to a lactide thermoplastic. In the examples, 5% by weight of calcium lactate as a nucleating agent was blended with an L, DL-lactide copolymer with a heating roll at a temperature of 170 ° C. for 5 minutes, and the sheet was rigid, strong and cloudy. , The degree of crystallinity increased.

Further, Japanese Patent Application Laid-Open No. 6-504799 (W)
O 92/04413) describes lactate and benzoate as core materials. Examples thereof include 1% calcium lactate mixed with a polylactide copolymer and a residence time of about 2 minutes. Injection molding was performed in a mold maintained at 85 ° C., but due to insufficient crystallization, about 110
An example of annealing at ~ 135 ° C is described.

[0009] In fact, injection molding was attempted using talc, silica, calcium lactate or sodium benzoate as a nucleating agent for a lactic acid-based polymer, but the crystallization rate was slow and the molded product was brittle. It was not possible to obtain a molded product that could withstand practical use. Therefore, such a lactic acid-based polymer has a low crystallization rate even when used for general injection molding, blow molding, and compression molding using ordinary talc, silica, etc., and the obtained molded article has a practical heat resistance of 100. Since the temperature is low below ℃ and the impact resistance is not strong, the application is restricted.

In Japanese Patent Application Laid-Open No. Hei 4-220456, polyglycolic acid and its derivatives are added to poly L-lactide and the like as nucleating agents, and the crystallization temperature is increased to shorten the injection molding cycle time. Moreover, it is described that it has excellent mechanical properties. As an example of injection molding, the crystallization temperature without a nucleating agent is a cooling time of 60
22.6% in seconds and 45.5% in nucleating agent addition. However, when injection molding was attempted without actually adding a nucleating agent to the lactic acid-based polymer, molding was performed under conditions where the mold temperature was equal to or higher than the Tg point, as described in JP-A-4-220456. I couldn't do that.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a molded article made of a lactic acid-based polymer having excellent heat resistance and impact resistance.

[0012]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have reached the present invention. That is, the present invention relates to lactic acid-based polymers 75 to 9
5% by weight and 5 to 25% by weight of poly-ε-caprolactone are mixed so that the L-lactic acid ratio becomes 75% by weight or more, and a crystalline inorganic material containing 50% or more of SiO _{2 in} 100 parts by weight of the composition Mix and melt 0.1 to 15 parts by weight of powder,
A heat-resistant lactic acid-based polymer molded product which is filled in a mold of a molding machine set at 85 to 125 ° C. and is molded while being crystallized, and a lactic acid having an L-lactic acid ratio of 75% by weight or more. -Based polymer 100 parts by weight, SiO ₂ 50%
0.1 to 15 parts by weight of a crystalline inorganic powder containing the above, and a polyester of an aliphatic polyhydric alcohol and an aliphatic polybasic acid or a polyester of an aliphatic polyhydric alcohol, an aliphatic polybasic acid and a hydroxycarboxylic acid Is mixed with 1 to 20 parts by weight, melted, filled in a mold of a molding machine set at 85 to 125 ° C., and molded while crystallizing, and a heat-resistant lactic acid-based polymer molded product, , 75 to 95% by weight of a lactic acid-based polymer and 5 to 25% by weight of poly-ε-caprolactone are mixed so that the L-lactic acid ratio becomes 75% by weight or more.
Crystalline inorganic powder 0.1-15 parts by weight, containing _two or more 50%, and an aliphatic polyhydric alcohol polyesters or aliphatic aliphatic polybasic acid polyhydric alcohol and aliphatic polybasic acid and hydroxycarboxylic 1 polyester acid
The present invention relates to a heat-resistant lactic acid-based polymer molded product which is mixed and melted in an amount of about 20 parts by weight, filled in a mold of a molding machine set at 85 to 125 ° C., and molded while being crystallized.

In the present invention, the lactic acid-based polymer is polylactic acid, lactic acid-hydroxycarboxylic acid copolymer, or a mixture of polylactic acid and lactic acid-hydroxycarboxylic acid copolymer, wherein the ratio of L-lactic acid in the polymer is 75% by weight or more. It is. Lactic acid and hydroxycarboxylic acid are used as raw materials for the polymer. As lactic acid, any of L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof, or lactide which is a cyclic dimer of lactic acid can be used. These lactic acids can be used in various combinations so that the L-lactic acid content in the obtained L-lactic acid-based polymer is 75% by weight or more. Hydroxycarboxylic acids that can be used in combination with lactic acids include glycolic acid,
There are 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, and 6-hydroxycaproic acid.
It is also possible to use monomers, for example, glycolide, which is a dimer of glycolic acid, or a cyclic ester intermediate such as ε-caprolactone.

The lactic acid-based polymer used in the present invention is L
-Direct dehydration using lactic acid having a lactic acid content of 75% by weight or more as a raw material or using a mixture of lactic acid and hydroxycarboxylic acid such that the L-lactic acid content in the mixture becomes 75% by weight or more. A method of polycondensation, or a cyclic dimer of lactic acid or hydroxycarboxylic acid as the cyclic dimer of lactic acid, for example, a cyclic ester intermediate such as glycolide or ε-caprolactone as a dimer of glycolic acid To obtain a ring-opening polymer.

In the case of production by direct dehydration polycondensation, the starting materials lactic acid or lactic acid and hydroxycarboxylic acid are azeotropically dehydrated and condensed, preferably in the presence of an organic solvent, especially a phenyl ether solvent, and particularly preferably azeotropically. The high-molecular-weight lactic acid-based polymer having a strength suitable for the present invention can be obtained by polymerizing the distilled solvent by removing water from the distilled solvent and returning the substantially anhydrous solvent to the reaction system. The weight average molecular weight of the lactic acid-based polymer is preferably a high molecular weight as long as the moldability is possible, and more preferably 30,000 or more. If the weight-average molecular weight is less than 30,000, the strength of the molded product may be low, which may be unsuitable for practical use. Even if the weight average molecular weight is 1,000,000 or more, it can be used for the production of the molded article of the present invention if the moldability is devised. On the other hand, if the weight average molecular weight exceeds 5,000,000, the moldability may be poor.

In the present invention, when a specific crystallization nucleating agent (hereinafter abbreviated as a nucleating agent) is used to crystallize a lactic acid-based polymer, the nucleating agent acts as a heterogeneous nucleus,
Nucleation is accelerated by reducing the surface free energy associated with nucleation. As a result, the polymer is faster during the molding process, and the molded product obtained by reaching a certain crystallization rate is expected to have improved heat resistance.

The nucleating agent is not limited to any commonly used nucleating agent. The nucleating agent generally used cannot increase the crystallization rate of the lactic acid-based polymer so much that the purpose cannot be achieved. As a nucleating agent suitable for crystallizing a lactic acid-based polymer, a crystalline inorganic powder is preferable, and a nucleating agent containing 50% by weight or more of SiO ₂ and having a hydroxyl group and being crystalline is preferable. When the nucleating agent Si0 ₂ minutes is less than 50 wt%, or if Si0 ₂ minutes amorphous even when more than 50% by weight,
The crystallization speed is too slow to be practical. The fact that the crystallization rate is low is also apparent from the fact that the heat of crystallization at the time of temperature decrease by differential scanning calorimetry (hereinafter abbreviated as DSC) of the molded product is small. The pH is not particularly limited,
In order to prevent a decrease in strength due to a decrease in the molecular weight of the lactic acid-based polymer, it is preferably 8.5 or less, more preferably 4 to 8. Specifically, crystalline Si0 ₂ minutes more than 50%, pH 8.5 following talc, crystalline Si0 ₂ minutes more than 50%, pH 8.5
The following kaolin and the like are particularly preferred. The amount used is 0.1 to 100 parts by weight of the lactic acid-based polymer and the dispersant.
15 parts by weight, preferably 0.5 to 7 parts by weight. 0.
If the amount is less than 1 part by weight, the effect of the nucleating agent may not be exhibited, and if the amount exceeds 15 parts by weight, the molecular weight tends to decrease, and as a result, unfavorable results in terms of physical properties are obtained. There is.

In the present invention, when a composition of a lactic acid-based polymer and a nucleating agent is crystallized, if a dispersing agent is used, the dispersibility of the nucleating agent in the lactic acid-based polymer is improved, and the crystallization speed is increased. A molded article excellent in heat resistance and impact resistance can be obtained uniformly. Preferred dispersants are poly-ε-caprolactone or styrene-butadiene-based thermoplastic elastomers. The poly-ε-caprolactone preferably has a weight average molecular weight of 50,000 to 250,000, and is preferably 100,000 to 15
Ten thousand are more preferred. When mixed with a lactic acid-based polymer, those having a high molecular weight can be used as long as they can be uniformly dispersed. Also, when using poly-ε-caprolactone,
In addition to the dispersing effect, the impact resistance is also improved.

The styrene-butadiene-based thermoplastic elastomer is a block copolymer using polystyrene as a hard segment and polybutadiene as a soft segment, and has a composition having a styrene / butadiene weight ratio of 20/80 to 45/55. Range, preferably 30
Those in the range of / 70 to 40/60 are preferred.

When mixing the dispersant with the lactic acid-based polymer,
Those having an L-lactic acid ratio of 75% by weight or more based on the whole mixture of the lactic acid-based polymer and the dispersant preferably have crystallinity. L-
If the lactic acid ratio is less than 75% by weight, the crystallinity may be inferior and a molded article having the desired heat resistance may not be obtained. When this is used, the amount of the dispersant added is preferably 5 to 25% by weight, more preferably 10 to 20% by weight, based on the lactic acid-based polymer. If the content exceeds 25% by weight, the strength of the molded product may be weak, and the molding processability may be poor and not suitable for practical use. If it is less than 5% by weight, the effect of the addition may be insufficient.

In the present invention, in order to promote crystallization,
Processability improvers can be used. Thereby, the crystallization rate of the lactic acid-based polymer is greatly accelerated, so that a molding cycle can be obtained as in a general-purpose resin such as a polypropylene resin. The processability improver of the present invention is not particularly limited, but has a weight average molecular weight of 10,000 to 1,000,000, preferably 50,000 to 500,000, more preferably 80,000 to 300,000, and more preferably 80,000 to 300,000. Polyesters of polybasic acids or polyesters of aliphatic polyhydric alcohols, aliphatic polybasic acids and hydroxycarboxylic acids are preferred. These polyesters include those in which the polymer chain is extended by a diisocyanate.

The amount of the processability improver used is 1 part by weight of the lactic acid-based polymer when used, and 1 part by weight based on 100 parts by weight of the lactic acid-based polymer and the dispersant when the dispersant is used. Preferably, it is added in an amount of 20 to 20 parts by weight, more preferably 5 to 15 parts by weight. If the amount exceeds 20 parts by weight, the rigidity of the molded product may be inferior, and a molded product not suitable for practical use may be produced. If the amount is less than 5 parts by weight, the effect of the addition may be insufficient. come. The aliphatic polyhydric alcohol is not particularly limited, but for example, 1,4-butanediol, ethylene glycol and the like can be used. The aliphatic polybasic acids are not particularly limited, and for example, succinic acid, adipic acid, and the like can be used. Further, the hydroxycarboxylic acid is not particularly limited, and examples thereof include lactic acid and the like. The diisocyanate is not particularly limited, but hexamethylene diisocyanate or the like can be used.

In the present invention, if necessary, a crystallization accelerator can be used to promote crystallization. By using a crystallization accelerator in combination with a nucleating agent, the crystallization rate of the lactic acid-based polymer is accelerated. As a result, the molding cycle is shortened, and a heat-resistant lactic acid-based polymer molded article having excellent heat resistance and impact resistance is obtained. Obtainable.

The crystallization accelerator of the present invention includes diisodecyl adipate (hereinafter abbreviated as DIDA), aliphatic dibasic acid esters such as n-octyl-n-decyl adipate, and polyhydric esters such as guserine triacetate. Alcohol esters and tributyl hydroxycarboxylates such as tributyl acetylcitrate are preferred. The amount of the crystallization promoter used is 0.1 to 8 parts by weight based on 100 parts by weight of the lactic acid-based polymer when using this, and 100 parts by weight of the lactic acid-based polymer and the dispersant when using the dispersant. Is preferable, and 1 to 5 parts by weight is more preferable. If the amount is less than 0.1 part by weight, the effect of the addition may be insufficient,
If it exceeds 8 parts by weight, undesired results may be given in terms of physical properties.

A composition comprising the lactic acid-based polymer of the present invention, a nucleating agent, and, if necessary, a dispersant, a processability improver, and a crystallization accelerator (hereinafter abbreviated as a lactic acid-based polymer composition).
, Various other modifiers may be added according to the purpose. Examples of the modifier include a stabilizer and an ultraviolet absorber. The lactic acid-based polymer composition can be kneaded by using a usual kneading method. To crystallize the lactic acid-based polymer composition, there are a method of annealing a molded product at a crystallization temperature, and a method of setting a molding die to the crystallization temperature when molding the composition and keeping it for a certain period of time.

A method for maintaining the crystallization temperature at a certain time when molding the composition is to set the mold temperature of the injection molding, blow molding and compression molding machines in a range from the crystallization start temperature to the end temperature when the temperature of the DSC is lowered. Then, the composition of the present invention is crystallized in a mold. By this method, a heat-resistant lactic acid-based polymer molded article having excellent heat resistance and impact resistance can be obtained. The mold temperature is 85-125 ° C, 90-1
15 ° C is preferred, and 100 to 110 ° C is more preferred.
Within this temperature range, the molded product can be easily crystallized and solidified when the molded product is taken out of the mold after molding, and a molded product with good dimensional accuracy can be obtained. If the temperature is out of this range, the crystallization speed may be low, and the solidification time of the molded product is required.

In the present invention, the lactic acid-based polymer composition can be produced by a known kneading technique, for example, mixing using a Henschel mixer, a ribbon blender, or the like, or further using a method involving hot melting using an extruder or the like. . The shape of the lactic acid-based polymer composition to be molded is a pellet, a rod,
Powders and the like are preferred.

Next, a method for producing a molded article using the lactic acid-based polymer composition of the present invention will be described in detail. A method for producing a lactic acid-based polymer molded product is produced by homogenizing a lactic acid-based polymer composition with a mixer, injection molding, blow molding, and compression molding.

As a method for producing a molded article having excellent heat resistance, the temperature of the mold for injection molding is 85 to 125 ° C., which is the temperature range from the crystallization start temperature to the end temperature when the DSC falls, preferably 95 to 110 ° C. In general, a lactic acid-based polymer is melted at 180 to 250 ° C. in a cylinder of a molding machine, filled in the mold, and then a crystallized molded product is taken out. For example, when 1 part by weight of a predetermined talc is added to 100 parts by weight of a lactic acid-based polymer, the crystallization start temperature at descent is 120.
° C and the end temperature are 95 ° C, and when 3 parts by weight of talc and 5 parts by weight of DIDA are used, the crystallization start temperature at descent is 114 ° C and the end temperature is 90 ° C. By setting the mold temperature within the crystallization temperature range, the effect of heat resistance can be obtained. In the case of blow molding, a parison extruded from a die attached to the tip of an extruder is inserted into a mold set at the above temperature, blown with air, and crystallized. In the case of compression molding, the composition is charged into a mold having a shape of a molded product set at 180 to 250 ° C., compression-molded, and then the mold is cooled to the above temperature to perform crystallization. The cooling time varies depending on the molding method and the shape and thickness of the molded product, but is approximately 1
0 to 100 seconds.

In the present invention, the heat resistant temperature means a Vicat softening point. Vicat softening point (ASTM-D152
5) refers to the temperature at which the needle enters the sample by 1 mm when the temperature is raised with a 1-mm diameter cylindrical needle placed on the sample and a load of 1 kg is applied. The Vicat softening point of the heat-resistant lactic acid-based polymer molded product of the present invention varies depending on the amount of a nucleating agent, dispersant, processability improver, crystallization accelerator, etc. 100-160 ° C, 120-160 ° C
Is preferably 130 to 150 ° C., and 140
C. to 150 C. is more preferred. The Vicat softening point of the lactic acid-based polymer molded article almost corresponds to the heat resistance test of the plastic container test method for a microwave oven (JIS-S 2033) which indicates the heat resistance of the molded article.
When the lactic acid-based polymer molded product was kept at 150 ° C. for 1 hour in a thermostat equipped with an air stirrer, no abnormality such as deformation of the container after cooling was observed. The molded article of the present invention can be molded efficiently with a molding machine that molds a general-purpose resin such as a polystyrene resin into a container having excellent heat resistance, and the molded article can be used for various purposes from daily necessities to sundries.
Especially used for microwave ovens.

[0031]

Next, the present invention will be described in detail with reference to examples. First, production of the lactic acid-based polymer used in the present invention will be described. In the following description, parts are all based on weight. The average molecular weight of the polymer (weight average molecular weight)
Was measured by gel permeation chromatography using polystyrene as a standard under the following conditions. Apparatus: Shimadzu LC-10AD Detector: Shimadzu RID-6A Column: Hitachi Chemical GL-S350DT-5, GL-S3
70DT-5 Solvent: chloroform Concentration: 1% Injection volume: 20 μl Flow rate: 1.0 ml / min

Production Example 1 100 parts of L-lactide and stannous octoate
01 parts and 0.03 parts of lauryl alcohol were sealed in a thick cylindrical stainless steel polymerization vessel equipped with a stirrer, degassed under vacuum for 2 hours, and then replaced with nitrogen gas. The mixture was heated at 200 ° C. for 3 hours with stirring under a nitrogen atmosphere. While maintaining the temperature as it was, the air was gradually degassed by a vacuum pump through an exhaust pipe and a glass receiver, and the pressure in the reaction vessel was reduced to 3 mmHg. One hour after the start of degassing, the distillation of the monomer and low-molecular-weight volatile components disappeared, so the inside of the container was replaced with nitrogen, the monomer was drawn out from the lower part of the container in a string form, and pelletized. A lactic acid-based polymer A was obtained. Weight average molecular weight Mw of this polymer
Was about 100,000. Tg was 59 ° C.

Production Example 2 A 100-liter reactor equipped with a Dien-Stark trap was charged with 90% pure L-lactic acid (L-lactic acid ratio: 100%).
After distilling water while stirring 0 kg at 150 ° C./50 mmHg for 3 hours, 6.2 g of tin powder was added, and 150 ° C./3
The mixture was stirred at 0 mmHg for another 2 hours to oligomerize.
To this oligomer, 28.8 g of tin powder and 21.1 kg of diphenyl ether were added, and an azeotropic dehydration reaction at 150 ° C./35 mmHg was carried out. The distilled water and the solvent were separated by a water separator, and only the solvent was returned to the reactor. Two hours later, the organic solvent to be returned to the reactor was passed through a column packed with 4.6 kg of molecular sieve 3A, and then returned to the reactor.
The reaction was performed at mmHg for 40 hours to obtain a polylactic acid solution having an average molecular weight of 110,000. The solution was diluted by adding 44 kg of dehydrated diphenyl ether, cooled to 40 ° C., and the precipitated crystals were filtered, washed three times with 10 kg of n-hexane, and dried at 60 ° C./50 mmHg. Add this powder to 0.
Add 12 kg of 5N HCl and 12 kg of ethanol and add 3
After stirring at 5 ° C for 1 hour, the mixture was filtered, and the mixture was filtered at 60 ° C / 50 mmHg.
Then, 6.1 kg of polylactic acid powder (85% yield) was obtained. This powder was melted and pelletized by an extruder to obtain a lactic acid polymer B having an L-lactic acid ratio of 100% by weight. The weight average molecular weight of this polymer was 110,000, and Tg was 59 ° C.

Production Example 3 A pellet was produced in the same manner as in Production Example 2 except that 100 parts of L-lactic acid was changed to 100 parts of DL-lactic acid to obtain a DL-lactic acid polymer C having an L-lactic acid ratio of 50% by weight. This polymer had a weight average molecular weight of about 110,000 and a Tg of 50 ° C.

Production Example 4 The procedure of Production Example 2 was repeated except that 100 parts of L-lactic acid was changed to 80 parts of L-lactic acid and 20 parts of glycolic acid as a hydroxycarboxylic acid component. A pellet D of the hydroxycarboxylic acid copolymer was obtained. The weight average molecular weight of this polymer was about 100,000. Tg is 4
9 ° C.

Production Example 5 Next, production of the processability improver used in the present invention will be described.
50.5 g of 1,4-butanediol and 66.5 succinic acid
g to 293.0 g of diphenyl ether and 2.02 to tin metal
g was added and heated and stirred at 130 ° C./140 mmHg for 7 hours while distilling water out of the system to oligomerize. Attach Dean Stark trap to this, 14
Perform azeotropic dehydration at 0 ° C./30 mmHg for 8 hours, and then
A tube filled with 40 g of molecular sieve 3A was attached, and the distilled solvent was returned to the reactor through the molecular sieve layer and stirred at 130 ° C./17 mmHg for 49 hours. The reaction mass was dissolved in 600 ml of chloroform, re-precipitated in 4 liters of acetone, sludged with an IPA solution of HCl (0.7 wt% of HCl) for 0.5 hour (three times), and washed with IPA. Reduced pressure from 60
The polymer was dried at 6 ° C. for 6 hours to obtain a polymer PSB. The weight average molecular weight of this polymer was 118,000.

Production Example 6 18.9 g of ethylene glycol and 34.25 g of succinic acid
Was added with 0.210 g of metallic tin, and 0.5 l /
Then, the mixture was heated and stirred while distilling water out of the system by flowing the solution for 1 minute, and the temperature was raised from room temperature to 150 ° C./1 atm over 1 hour. This is Dean S
Attach mark trip and diphenyl ether 1
55 g was added, and an azeotropic dehydration reaction was performed at 150 ° C./38 mmHg for 8 hours to remove water, and thereafter, Dean Sta.
Remove rk trip and remove molecular sieve 5A, 2
A tube filled with 0 g was attached so that the distilling solvent returned to the system again through the molecular sieve. 13
The reaction was performed at 0 ° C. for 34 hours. Before stopping this reaction,
As a result of sampling and analyzing a small amount of the distilled solvent just before returning to the reaction mass after coming into contact with the molecular sieve, the amount of water in the solvent was 5 ppm or less and the amount of ethylene glycol was 10 ppm or less, which is the detection limit. Next, the reaction mass was dissolved in 500 ml of chloroform, and 5.8 was added.
After adding to 1 liter of acetone and reprecipitating, it was dried at 60 ° C. under reduced pressure for 6 hours to obtain a polymer PSE. The weight average molecular weight of this polymer was 139,000.

Hereinafter, an example of a method for producing a molded product of an L-lactic acid-based polymer according to the present invention using the lactic acid-based polymer obtained in Production Examples 1 to 4 will be described. The main measurement conditions of physical properties are as follows. 1) Crystallization temperature at the time of DSC descent According to differential scanning calorimetry (DSC-50, manufactured by Shimadzu Corporation), a sample amount of 5 mg of pellets was 200 at 10 ° C./min.
After raising the temperature to ° C, the sample held for 5 minutes was measured at a temperature decreasing rate of 5 ° C / min. 2) Crystallinity X-ray diffractometer (Rig 1500 type, manufactured by Rigaku Corporation)
Measure the test specimen after molding. 3) Heat resistance The Vicat softening temperature (ASTM-D1525) is set at a load of 1k.
Measure the test piece after molding under the condition of gf. 4) Impact strength Measured using a notched specimen of Izod impact strength (ASTM-D256). 5) Degradability test A 2 × 5 cm test piece was sampled, and the test piece was taken at a temperature of 35 ° C.
The sample was buried in a soil having a water content of 30% and subjected to a decomposition test to determine the change in appearance and the rate of weight loss.

In the following examples, examples are shown in which a dispersant is added to a lactic acid-based polymer. [Use of dispersant] Examples 1 to 5 Lactic acid polymers A to D obtained in Production Examples 1 to 4 and poly-ε-capractone as a dispersant (trade names: TONE, P
-787 or less, abbreviated as PCL) or a styrene-butadiene-based thermoplastic elastomer (trade name; abbreviated as SB, hereinafter referred to as Asahi Kasei, Tufprene A), and talc as a nucleating agent (60% of SiO ₂ made by Fuji Talc, crystalline), As crystallization promoters, diisodecyl adipate (hereinafter abbreviated as DIDA) and tributyl acetyl citrate (hereinafter ATBC)
) In a ratio shown in Table 1 using a Henschel mixer, and then pelletized under the conditions of an extruder cylinder set temperature of 170 to 210 ° C. The pellets were heated at a cylinder setting temperature of 180-200 JSW-75 injection molding machine manufactured by Japan Steel Works, Ltd.
Melted under the condition of 200 ° C., filled in a mold at a set temperature of 100 ° C., and obtained a molded product of a test piece for ASTM physical properties in Examples 1 to 3 and 5 for 30 seconds and Example 4 for 80 seconds. Was. Table 1 shows the evaluation results of the test pieces.

[Use of processability improver] Examples 6 to 7 Lactic acid polymer B obtained in Production Example 2, nucleating agent, crystallization accelerator, and PS obtained in Production Example 5 as a processability improver
B or PSE obtained in Production Example 6 was mixed at a ratio shown in Tables 1 and 2 with a Henschel mixer, and then pelletized in the same manner as in Example 1 to obtain a molded product of a test piece for ASTM physical properties.
The cooling time of the mold could be reduced to 20 seconds. Tables 1 and 2 show the evaluation results of the test pieces.

[Use of dispersant and processability improver] Example 8 Lactic acid polymer B obtained in Production Example 2, dispersant, nucleating agent,
The crystallization accelerator and the processability improver were mixed in a Henschel mixer at the ratios shown in Table 2, and then pelletized in the same manner as in Example 2 to obtain a molded product of a test piece for ASTM physical properties. The cooling time of the mold could be reduced to 20 seconds. Table 2 shows the evaluation results of the test pieces.

[Types of nucleating agent] Examples 9 to 11 As the lactic acid-based polymer B obtained in Example 2, a dispersant, a crystallization accelerator and a nucleating agent, kaolin JP-100 (SiO ₂
Min 80%, crystalline), silica (SiO ₂ min 97%,
(Crystallinity) and kaolin clay (SiO ₂ content: 80%, crystallinity) were added in an amount of 3% by weight, and pelletized in the same manner as in Example 1 to obtain a molded product of a test piece for ASTM physical properties. Table 2 shows the test results. The nucleating agent is crystalline and the SiO ₂ content is 50
% Or more, the moldability and the heat resistance of the molded product were good.

[No use of dispersant and processability improver] Comparative Example 1 Using the lactic acid-based polymer B obtained in Production Example 2, without mixing the dispersant, the nucleating agent and the crystallization accelerator are shown in Table 3. After mixing with the Henschel mixer shown, the mixture was pelletized in the same manner as in Example 1 to obtain a molded product of a test piece for ASTM physical properties. Table 3 shows the test results. Since the molded product did not contain the dispersant PCL, the nucleating agent was poorly dispersed and was locally aggregated. Also, the impact strength was reduced.

[L-lactic acid ratio] Comparative Example 2 The lactic acid-based polymers A and C obtained in Production Examples 1 and 3 were mixed with a dispersant to make the L-lactic acid ratio 60%, and the nucleating agent and the crystal were mixed. The mixing accelerators were mixed at the ratios shown in Table 3 using a Henschel mixer, and then pelletized in the same manner as in Example 2 to obtain molded articles of test pieces for ASTM physical properties. Table 3 shows the evaluation results of the test pieces. Even when a nucleating agent was added to the obtained molded product, the L-lactic acid ratio of the polymer was less than 75% by weight, so that the molded product was deformed when removed from the mold.

[No nucleating agent, crystallization accelerator, processability improver used] Comparative Example 3 Using the lactic acid-based polymer B pellets obtained in Production Example 2, a cylinder set temperature of an injection molding machine of 180 to 200 ° C
Was melted under the following conditions, filled in a mold at a set temperature of 100 ° C., and a molded product of a test piece for ASTM physical properties was obtained under the conditions of a cooling time of 80 seconds. Table 3 shows the evaluation results of the test pieces. Since the obtained molded product did not contain a nucleating agent in the polymer, it was too soft when taken out of the mold and was greatly deformed.

[Amount of nucleating agent] Comparative Example 4 The lactic acid-based polymer B obtained in Production Example 2 was changed to the dispersing agent, except that the nucleating agent was changed from 0.1 to 15 parts by weight to 20 parts by weight. A molded product was obtained in the same manner as in Example 2. Table 3 shows the results.
In the obtained molded product, a decrease in strength due to a decrease in molecular weight was observed.

[Amount of Crystallization Accelerator] Comparative Example 5 11 parts by weight of lactic acid-based polymer B, dispersant and nucleating agent obtained in Production Example 2 exceeding 0.1 to 8% by weight of crystallization accelerator A molded article was obtained in the same manner as in Example 2 except that the composition was changed to. Table 3 shows the results. In the obtained molded product, a decrease in strength due to a decrease in molecular weight was observed.

[Amount of processability improver] Comparative Example 6 The lactic acid-based polymer B obtained in Production Example 2, the dispersant and the processability improver were changed to 30 parts by weight exceeding 1 to 20 parts by weight. A molded product was obtained in the same manner as in Example 6. Table 3 shows the results. The dimensional accuracy of the obtained molded product was poor, and a stable molded product could not be obtained.

[Types of Nucleating Agent] Comparative Examples 7 to 11 The lactic acid-based polymer B obtained in Production Example 2, a dispersing agent, a crystallization promoter and a nucleating agent containing less than 50% of SiO ₂ and containing crystalline kaolin UW (SiO ₂ content 45%, crystalline), Kaolinite (SiO ₂ content 45%, crystalline), Talc R
F (SiO ₂ content 40%, crystalline) and SiO ₂ 50%
As described above, amorphous synthetic silica (SiO ₂ content: 90%) and silica (SiO ₂ content: 90%) were added in an amount of 3% by weight, and pelletized in the same manner as in Example 1 to form test pieces for ASTM physical properties. Tried. Table 4 shows the composition ratio. However, the molded product was too soft when taken out of the mold, was greatly deformed, and the physical properties could not be measured.

[Evaluation of Moldability According to Molding Conditions] Examples 12 to 13 Lactic acid polymer B obtained in Production Example 2, dispersant, nucleating agent,
And a crystallization accelerator in the proportions shown in Table 5 in the same manner as in Example 2 and pelletized.
Melt under the condition of 0 to 200 ° C and set the mold temperature to DS
95 within the peak range of the crystallization temperature at the time of cooling measured at C
C. and 110 ° C. to obtain a molded product in the same manner as in Example 2. Table 5 shows the evaluation results of the test pieces.

Comparative Examples 12 to 14 The lactic acid-based polymer B obtained in Production Example 2, a dispersant, a nucleating agent,
And a crystallization accelerator in the proportions shown in Table 5 in the same manner as in Example 2, and pelletized at an injection molding machine cylinder set temperature of 1
Melted under the condition of 80 to 200 ° C and set the mold temperature to D
A molded product was obtained in the same manner as in Example 2 except that the temperature was lowered outside the peak range of the crystallization temperature upon cooling measured by SC. Comparative Example 12: The set temperature of the mold was set to 30 ° C.
Comparative Example 13 was set at 130 ° C., and Comparative Example 14 was set at 80 ° C. Table 5 shows the evaluation results of the test pieces.
Shown in The molded product obtained in Comparative Example 7 was inferior in heat resistance due to its amorphous nature. The molded articles obtained in Comparative Examples 8 and 9 were amorphous when the mold temperature was equal to or higher than the Tg point, and were too soft when taken out of the mold and were greatly deformed.

Comparative Example 15 A polypropylene resin was used in place of the lactic acid-based polymer A of Example 1, and the mold temperature was set to a normal set temperature of 30 ° C.
A molded product of a test piece for ASTM physical properties was obtained in the same manner as in Example 1 except for the above. Table 5 shows the measurement results of the test pieces. The obtained molded product has poor soil degradability.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

The lactic acid-based polymer molded article of the present invention is excellent in heat resistance and impact resistance, and is suitably used for heat resistance of microwave ovens, food trays, drink cups and the like. Furthermore, when it is buried underground or dumped into the sea or river as waste, it decomposes into harmless water and carbon dioxide within a relatively short period of time in the natural environment, just like natural products such as paper and wood. I do.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhiro Kitahara 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Masanobu Amioka 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical (56) References JP-A-5-247245 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 67/04

Claims (10)

(57) [Claims] 1. A composition 100 containing 75 to 95% by weight of a lactic acid-based polymer and 5 to 25% by weight of poly-ε-caprolactone so that the ratio of L-lactic acid is 75% by weight or more.
0.1 to 15 parts by weight of a crystalline inorganic powder containing 50% or more of SiO ₂ is mixed and melted at 85 to 125 ° C.
A method for producing a heat-resistant lactic acid-based polymer molded product, wherein the molded product is filled in a mold of a molding machine set in (1) and crystallized while being crystallized. 2. 100 parts by weight of a lactic acid-based polymer having an L-lactic acid ratio of 75% by weight or more, 0.1 to 15 parts by weight of a crystalline inorganic powder containing 50% or more of SiO ₂ , and an aliphatic polyhydric alcohol. 1 to 20 parts by weight of an aliphatic polybasic acid polyester or an aliphatic polyhydric alcohol, an aliphatic polybasic acid and a hydroxycarboxylic acid polyester are mixed and melted, and the gold of a molding machine set at 85 to 125 ° C. A method for producing a heat-resistant lactic acid-based polymer molded article, wherein the molded article is filled in a mold and crystallized while being crystallized. 3. The polyester of an aliphatic polyhydric alcohol and an aliphatic polybasic acid, or 1 to 20 parts by weight of a polyester of an aliphatic polyhydric alcohol, an aliphatic polybasic acid and a hydroxycarboxylic acid. A method for producing the heat-resistant lactic acid-based polymer molded article according to the above. 4. A molding machine injection molding machine, one of the claims 1-3 is either blow molding machine or compression molding machine
Method for producing a heat-resistant lactic acid-based polymer molded article of Kaniki mounting. 5. The aliphatic dibasic acid ester, polyhydric alcohol ester or any of claims 1-3 hydroxy polyvalent carboxylic acid tributyl mixing 0.1-8 parts by weight,
Method for producing a heat-resistant lactic acid-based polymer molded article of Kaniki mounting. 6. 100 parts by weight of a composition comprising 75 to 95% by weight of a lactic acid-based polymer and 5 to 25% by weight of poly-ε-caprolactone and having an L-lactic acid ratio of 75% by weight or more;
crystalline inorganic powder containing iO ₂ 50% or more 0.1
A heat-resistant lactic acid-based polymer molded product comprising 5 parts by weight and having a heat-resistant temperature of 100 to 160 ° C. 7. 100 parts by weight of a lactic acid-based polymer having an L-lactic acid ratio of 75% by weight or more, 0.1 to 15 parts by weight of a crystalline inorganic powder containing 50% or more of SiO ₂ , and an aliphatic polyhydric alcohol. A lactic acid-based polymer composition comprising 1 to 20 parts by weight of a polyester of an aliphatic polybasic acid or a polyester of an aliphatic polyhydric alcohol, an aliphatic polybasic acid and a hydroxycarboxylic acid. 8. The heat-resistant temperature obtained by molding the lactic acid-based polymer composition according to claim 7 is 100 to 160.
Heat-resistant lactic acid-based polymer molded product whose temperature is ° C. 9. 100 parts by weight of a composition comprising 75 to 95% by weight of a lactic acid-based polymer and 5 to 25% by weight of poly-ε-caprolactone and having an L-lactic acid ratio of 75% by weight or more, Si
0.1 to 15 crystalline inorganic powder containing 50% or more of O ₂
Parts by weight, polyester of aliphatic polyhydric alcohol and aliphatic polybasic acid or polyester of aliphatic polyhydric alcohol, aliphatic polybasic acid and hydroxycarboxylic acid 1
A lactic acid-based polymer composition comprising -20 parts by weight. 10. The heat-resistant temperature obtained by molding the lactic acid-based polymer composition according to claim 9 is 100 to 16.
A heat-resistant lactic acid-based polymer molded article at 0 ° C.