JP2000044716A - Composition for producing polylactate foam, production of foam, and foam obtained thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having excellent foamability and moldability by incorporating a dispersible copolymer obtained by dehydratively condensing a polysaccharide with at least either lactic acid or a polylactic acid and having a specified melt tension with an inorganic filler foaming nucleator a blowing aid, and a volatile blowing agent. SOLUTION: A polysaccharide such as acetylcellulose having a weight-average molecular weight of 3,000-500,000 is dehydratively condensed with at least either lactic acid or a polylactic acid to obtain a degradable copolymer having a melt tension of 0.7-20 g at a melt flow index of 10 g/10 min. 100 pts.wt. obtained copolymer is mixed with 0.1-5 pts.wt. inorganic filler blowing nucleator such as talc having a mean particle diameter of 1-10 μm, 0.01-0.5 pt.wt. blowing aid such as calcium stearate, and 0.1-20 pts.wt. volatile blowing agent such as methyl chloride or carbon dioxide to obtain the objective composition. This composition is extruded at 150-250 deg.C with e.g. a tandem foaming extruder to obtain a foam having an expansion ratio of 5-30 and a cell diameter of 100-600 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composition for producing a polylactic acid-based foam. Further, the present invention relates to a method for producing a polylactic acid-based foam, a foamed article as a molded product, and a sheet.

[0002]

2. Description of the Related Art In general, foamed materials are manufactured from resins such as polyethylene, polypropylene, and polystyrene, and are used in other fields by making use of performances such as light weight, heat insulation, sound insulation, and cushioning. However,
These foamed materials are difficult to be recovered and reused after use, and are hardly decomposed in a natural environment, so that they remain semi-permanently in the ground. In addition, abandoned plastics have caused problems such as spoiling the landscape and destroying the living environment of marine life.

On the other hand, lactic acid-based polymers such as polylactic acid and copolymers of lactic acid and other aliphatic hydroxycarboxylic acids, and aliphatic polyhydric alcohols and aliphatic polyhydric alcohols include thermoplastic resins having biodegradability. Aliphatic polyesters derived from carboxylic acids have been developed.

Some of these polymers are 100% biodegradable within a few months to a year in animals or, when placed in soil or seawater, begin to degrade within weeks in moist environments. Disappears in about one to several years. Furthermore, the decomposition products have the property of becoming lactic acid, carbon dioxide, and water that are harmless to the human body.

[0005] In particular, polylactic acid, in particular, has recently been able to produce L-lactic acid as a raw material in large quantities and inexpensively by a fermentation method, has a high decomposition rate in compost, has resistance to mold, and has a high resistance to food. Due to its excellent characteristics such as odor resistance and coloring resistance, it is expected that its field of use will be expanded. However, since polylactic acid generally has a low melt tension, there remains an insufficient point for molding methods such as foam molding. That is, since there is no sufficient melt tension when melt-molding, it is difficult to obtain a high-magnification foam molded body,
Another problem is that it is difficult to find appropriate foam molding conditions.

JP-A-4-304244, JP-A-5-304244
JP-A-140361, JP-A-6-287347, etc., describe a molding technique relating to foaming of a polylactic acid-based resin composition, but effectively perform foam molding of an aliphatic polyester such as polylactic acid. The method is still inadequate.

Japanese Patent Application Laid-Open No. 9-143253 discloses a technique in which a polysaccharide and an aliphatic polyester such as lactic acid are copolymerized to increase the melt tension. There are problems such as difficulty in uniformity and control, and it is not yet sufficient.

In general, when the cell diameter is large, the cell becomes conspicuous to the naked eye and the appearance is deteriorated. Therefore, usually, to improve the appearance, a method is adopted in which the surface is quenched with water or air after extrusion to suppress the generation of bubbles only on the surface. Although the physical properties tend to be better when the cell diameter is uniform up to the inner layer, a technique for controlling the cell diameter up to the inner layer of the foam has not yet been found.

[0009]

The problem to be solved by the present invention is to provide a polylactic acid-based resin composition having excellent foamability and moldability during foam molding, a method for producing a foam,
It is to provide a foam and a sheet.

[0010]

Means for Solving the Problems The present inventors have made intensive studies on polylactic acid-based resins, and as a result, added a specific foaming nucleating agent and a foaming auxiliary to a copolymer comprising a polysaccharide and an aliphatic polyester at a specific ratio. As a result, the present inventors have found a foamable resin composition and a method for producing a foam that satisfy the above-mentioned problems, and have completed the present invention. That is, the present invention is specified by the following items [1] to [17].

[1] (1) Polysaccharide (A) and (b1)
A melt tension of 0.7 to 20 g at a melt flow index of 10 g / 10 min obtained by subjecting at least one kind (B) selected from the group consisting of lactic acid and (b2) polylactic acid to a dehydration polycondensation reaction; Degradable copolymer 100
At least (2) an average particle diameter of 1 to 10 μm with respect to parts by weight
0.1 to 5.0 parts by weight of an inorganic filler foam nucleating agent,
(3) 0.01 to 0.5 parts by weight of a foaming aid, and (4) 0.1 to 20 parts by weight of a volatile foaming agent.
A composition for producing a polylactic acid-based foam.

[2] The inorganic filler foam nucleating agent is talc,
The composition for producing a polylactic acid-based foam according to [1], wherein the foaming aid is a stearic acid-based compound and / or a montanic acid-based compound.

[3] The composition for producing a polylactic acid-based foam according to [1] or [2], wherein the polysaccharide is acetyl cellulose and / or ethyl cellulose.

[4] A polylactic acid-based foam obtained by melt-kneading the composition according to any one of [1] to [3].

[5] A polylactic acid-based foamed sheet obtained by melt-kneading the composition according to any one of [1] to [3].

[6] A method for producing a polylactic acid-based foam, which comprises melt-kneading the composition according to any one of [1] to [3] to obtain a foam.

[7] A method for producing a polylactic acid-based foam sheet, comprising melt-kneading the composition according to any one of [1] to [3] to obtain a foam sheet.

[8] A polylactic acid-based molded article obtained by subjecting the foamed sheet according to [5] to either a vacuum forming method or a vacuum pressure forming method.

[9] (1) Polysaccharide (A) and (b1)
A melt tension of 0.7 to 20 g at a melt flow index of 10 g / 10 min obtained by subjecting at least one kind (B) selected from the group consisting of lactic acid and (b2) polylactic acid to a dehydration polycondensation reaction; Degradable copolymer 100
At least (2) an average particle diameter of 1 to 10 μm with respect to parts by weight
0.1 to 5.0 parts by weight of an inorganic filler foam nucleating agent,
(3) When melt molding a resin composition comprising 0.01 to 0.5 parts by weight of a foaming aid, (4) a volatile foaming agent of 0.1 to 0.5 parts by weight.
A method for producing a polylactic acid-based foam, comprising adding 20 parts by weight and foaming.

[10] (1) Polysaccharide (A) and (b)
1) Lactic acid, (b2) obtained by a dehydration polycondensation reaction with at least one kind (B) selected from the group consisting of polylactic acid,
Degradable copolymer 1 having a melt flow index in the range of 0.7 to 20 g at a melt flow index of 10 g / 10 min.
At least (2) an average particle size of 1 to 1
When melt molding a resin composition comprising 0.1 to 5.0 parts by weight of an inorganic filler foam nucleating agent of 0 μm and (3) 0.01 to 0.5 part by weight of a foaming aid, (4) volatile type Foaming agent 0.
A method for producing a polylactic acid-based foamed sheet, comprising adding 1 to 20 parts by weight and foaming.

[11] The method for producing a polylactic acid-based foam according to [9], wherein the inorganic filler foam nucleating agent is talc and the foaming aid is a stearic acid-based compound and / or a montanic acid-based compound.

[12] The method for producing a polylactic acid-based foam according to [9] or [11], wherein the polysaccharide is acetyl cellulose and / or ethyl cellulose.

[13] The method for producing a polylactic acid foam sheet according to [10], wherein the inorganic filler foam nucleating agent is talc and the foaming aid is a stearic acid compound or a montanic acid compound.

[14] The polysaccharide is acetyl cellulose and / or ethyl cellulose [10] or [13].
The method for producing a polylactic acid-based foamed sheet described in 1 above.

[15] A polylactic acid-based foam obtained by any method according to any one of [9] to [14].

[16] A polylactic acid-based foam sheet obtained by any of the methods described in any of [9] to [14].

[17] A polylactic acid-based molded article obtained by subjecting the foamed sheet according to [16] to either a vacuum forming method or a vacuum pressure forming method.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[Degradable copolymer] The degradable copolymer in the present invention includes polysaccharide (A), (b1) lactic acid, (b)
2) A copolymer obtained by a dehydration polycondensation reaction with at least one kind (B) (polylactic acid component) selected from the group consisting of polylactic acid.

[Copolymerization of polysaccharide and polylactic acid component] In the present invention, the copolymerization of the polysaccharide and the polylactic acid component is carried out by mixing the polysaccharide and lactic acid and copolymerizing them. Mixed with
Copolymerization Method Any method of mixing a polysaccharide with lactic acid and a previously produced polylactic acid and copolymerizing the mixture may be used.

[Melt Tension of Degradable Copolymer] The melt tension of the degradable copolymer of the present invention is in the range of 0.7 to 20 g. If it is less than 0.7 g, the melt tension is not sufficient, so that a good foam cannot be obtained. If the amount exceeds 20 g, foaming may be more difficult depending on foaming extrusion conditions.

[Molecular Weight of Degradable Copolymer] The molecular weight of the degradable copolymer obtained in the present invention is determined by the weight average molecular weight (Mw).
Is in the range of 30,000 to 2,000,000. Preferably 50,000 to 15
The range is 100,000, more preferably 100,000 to 1,000,000. If it is less than 10,000, the mechanical properties of the foamed molded article obtained may not be sufficient or the melt tension may not be sufficiently improved. If it exceeds 2,000,000, handling becomes difficult, for example, the viscosity becomes too high and foaming becomes difficult, or the production cost is high, which may be uneconomical.

[Raw material of polylactic acid component] In the present invention,
Specific examples of lactic acid as a raw material of polylactic acid include 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 mentioned.

[Polysaccharide] The polysaccharide in the present invention includes:
For example, regenerated cellulose such as cellulose, cellulose nitrate, acetylcellulose, methylcellulose, ethylcellulose, CMC, nitrocellulose, cellophane, viscose rayon and cupra, hemicellulose, starch, amylopectin, dextrin, dextran, glycogen, pectin, chitin, chitosan or a mixture thereof Derivatives and the like. Among these, acetyl cellulose and ethyl cellulose are particularly preferred. These may be used alone or in combination of two or more.

[Molecular Weight of Polysaccharide] The molecular weight of the polysaccharide in the present invention depends on the kind of the polysaccharide, but the weight average molecular weight (Mw) is in the range of 3000 to 500,000. It is preferably in the range of 10,000 to 400,000, more preferably in the range of 100,000 to 300,000. If it is less than 3000, the melt tension may not be sufficiently improved. If it exceeds 500,000, melting and melting may be difficult.

[Addition amount of polysaccharide] The amount of polysaccharide used in the present invention is 0.1 to 10 based on the obtained degradable copolymer.
%, Preferably in the range of 0.5 to 5% by weight. If the amount is less than 0.1% by weight, the obtained decomposable copolymer has insufficient melt tension, and if it exceeds 10% by weight, it becomes difficult to obtain a copolymer having a high molecular weight.

[Production Method] As a specific example of the production method used in the present invention, for example, a method in which lactic acid is used as a raw material for direct dehydration polycondensation (for example, disclosed in US Pat. No. 5,310,865) Production method), a ring-opening polymerization method for melt-polymerizing a cyclic dimer of lactic acid (lactide) (for example, a production method disclosed in US Pat. No. 2,758,987), a cyclic method of lactic acid and an aliphatic hydroxycarboxylic acid. Dimer,
For example, a ring-opening polymerization method in which lactide or glycolide and ε-caprolactone are melt-polymerized in the presence of a catalyst (for example, a production method disclosed in US Pat. No. 4,057,537), and the like can be mentioned. However, the production method is not particularly limited.

As a method for producing a degradable copolymer of a polysaccharide and polylactic acid, a method similar to the above-mentioned method for producing polylactic acid can be used, but the method is not limited thereto.

The molecular weight may be increased by using a binder (polymer chain extender) such as a diisocyanate compound.

[Production method] As a production technique for copolymerizing a polysaccharide and an aliphatic polyester such as lactic acid, Japanese Patent Application Laid-Open No. 9-143 is disclosed.
253 can be used.

[Types of volatile blowing agent] Examples of the volatile blowing agent used in the present invention include hydrocarbons such as ethane, butane, pentane, hexane, heptane, ethylene, propylene, petroleum ether, methyl chloride, and monochloro. Examples include halogenated hydrocarbons such as trifluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane, carbon dioxide gas, and water.

[Amount of Volatile Foaming Agent] The amount of volatile foaming agent added was 0.1 to 100 parts by weight of the decomposable copolymer.
It is in the range of ２０20 parts by weight. Preferably, 0.5 to 15
Parts by weight, more preferably in the range of 1.0 to 10 parts by weight. If the amount is less than 0.1 part by weight, the effect as a foaming agent is not sufficient. If the amount exceeds 20 parts by weight, poor appearance may be caused.

[Types of Foaming Aids] The foaming aids in the present invention include calcium stearate, zinc stearate, barium stearate, magnesium stearate, aluminum stearate, stearic acid and other stearic acid-based compounds, and calcium montanate. , Zinc montanate, barium montanate, magnesium montanate,
Examples thereof include montanic acid compounds such as aluminum montanate and montanic acid, paraffin, and stearamide. Of these, stearic acid compounds and montanic acid compounds are particularly preferred. Further, calcium stearate and calcium montanate are particularly preferred.

[Types of Inorganic Filler Foaming Nucleating Agent] As the inorganic filler foaming nucleating agent in the present invention, talc, silica,
Examples include inorganic fillers such as calcium carbonate, clay, zeolite, kaolin, bentonite, aluminum oxide, and magnesium carbonate. Of these, talc is particularly preferred. Especially Micro Ace L-1 (manufactured by Nippon Talc)
Is preferred.

[PH of talc] The talc used in the present invention preferably has a pH of 5 to 10. More preferably, it is in the range of 7-10. If the pH is less than 5,
In some cases, the metal parts of the extruder cylinder may be oxidized and damaged. If the pH exceeds 10, the molecular weight of the degradable copolymer may be significantly reduced in some cases.

[Average Particle Size of Inorganic Filler Foaming Nucleating Agent] The average particle size of the inorganic filler foaming nucleating agent in the present invention is from 0.1 to 0.1%.
It is in the range of 10 μm. It is preferably in the range of 1 to 10 μm, more preferably 1 to 5 μm, and still more preferably 1 to 2 μm. Outside this range, a foam having a uniform cell diameter cannot be obtained.

[Amount of Inorganic Filler Foaming Nucleating Agent and Foaming Aid] The amount of the inorganic filler foaming nucleating agent is in the range of 0.1 to 5.0 parts by weight based on 100 parts by weight of the decomposable copolymer. The amount of the foaming aid is 0.1 to 100 parts by weight of the decomposable copolymer.
The range is from 0.01 to 0.5 parts by weight. It is preferably in the range of 0.5 to 1.0 part by weight of a foam nucleating agent and 0.1 to 0.5 part by weight of a foaming aid. Outside of these ranges, a foam having a desired uniform cell diameter cannot be obtained. In addition, there are cases where molding cannot be performed stably.

[Foam Extrusion Molding] As a foam extrusion apparatus used to obtain a foam or a foam sheet by extrusion foam molding, a single-screw extruder, a twin-screw extruder, and a tandem-type foam in which two single shafts are connected. Extrusion equipment is mentioned. For the production of the foam and the foamed sheet of the present invention, a tandem type foam extruder is more preferable in terms of efficiency. As the screw used for the extruder, a screw used for ordinary extrusion molding may be used, and an L / D in the range of 28 to 35 is usually good. As the die used for the extruder, any of a circular die, a capillary die, a T die and the like may be used according to a desired foam shape.

The die pressure is usually in the range of 2 to 10 MPa. The die temperature depends on the type and molecular weight of the polylactic acid-based resin composition to be used, but is usually in the range of 130 to 150 ° C. The extruder is usually fitted with a gas leakage prevention ring. Cylinder temperature around the ring is 170-200 ° C
It is essential that the resin is completely melted.

The extrusion temperature is usually in the range of 150 to 250 ° C., though it depends on the type and molecular weight of the polylactic acid resin composition to be used. It is more preferably in the range of 160 to 230 ° C, most preferably in the range of 170 to 200 ° C.

It is preferable to rapidly cool the resin extruded from the die at the time of foaming to prevent dissipation of the foaming agent. For this purpose, it is desirable to install a cooling device after the extruder, and the cooling is performed by a method of blowing air or the like, a method of passing the same through water, a method of spraying them, or the like. The extruded foam can be wound into a roll by installing a mandrel, a cutter, a take-up machine and a take-up machine.

[Cell diameter of foam] In general, the cell diameter of a foam affects the appearance. The cell diameter of the foam obtained by the present invention is in the range of 100 to 600 μm. Preferably 1
00 to 500 μm, more preferably 100 to 400 μm
m, most preferably in the range of 100 to 300 μm.
If there is a cell exceeding 600 μm, the appearance becomes poor. In the present invention, cells having a size of less than 100 μm accounted for a very small percentage of the whole and were ignored.

[Expansion Ratio] The expansion ratio of the foam obtained by the present invention is in the range of 5 to 30 times. Preferably 10-2
The range is 5 times, more preferably 10 to 20 times. When the volatile foaming agent is used, the one having a cell diameter less than 5 times or more than 30 times cannot obtain a cell having a uniform cell diameter.

[Other Additives] In the present invention, a lubricant, a filler, a coloring agent, a plasticizer, an ultraviolet absorber, an antioxidant, etc. may be added as long as the purpose is not impaired.

[Foam Sheet] The foam sheet obtained by the present invention can be subjected to secondary processing such as vacuum forming and vacuum pressure forming.

[Vacuum Forming] A method in which a foamed sheet heated and softened in a vacuum forming or vacuum pressure forming mold is guided into a mold, and at the same time, the inside of the mold is formed under reduced pressure by a vacuum pump. In particular, when it is desired to make the deep drawing container or the wall thickness uniform, it is desirable to use a molding plug and synchronize with the compressed air for molding. The sheet heating method is roughly classified into two methods, an "indirect heating method" and a "direct heating method". The "indirect heating method" is a method of heating the sheet by irradiating the sheet with far infrared rays such as a ceramic heater, while the "direct heating method" is a method of heating the sheet by directly contacting the sheet with a heating plate. In the present invention, there is no limitation on the heating method of the sheet, and any method can be used. The heating temperature of the sheet when performing vacuum forming or vacuum pressure forming can be generally performed in a temperature range from the glass transition temperature to the melting point of the aliphatic polyester resin, and may be any condition, and there is no limitation. The degree of pressure reduction and the pressure of the compressed air are not particularly limited, and conditions having good shapeability of the molding container can be appropriately selected.

[Applications] The foams and foam sheets obtained by the present invention, and the molded products obtained by vacuum-forming and vacuum-pressure forming them (these are referred to as “foam products obtained by the present invention”) It can also be used as a substitute for the use of publicly known foams. In particular, the foamed product of the present invention is suitably used as a substitute for a general-purpose resin foam used for difficult-to-collect or disposable foamed containers, cushioning (packaging) materials, materials for the civil engineering industry, materials for the agricultural and marine industries, and leisure goods. be able to.

General-purpose use The foamed product obtained by the present invention can be used, for example, in a lunch box, tableware, a container for lunches and prepared dishes, a cup for cup ramen, and a vending machine for beverages, which are sold in convenience stores. Cups, containers and trays for foodstuffs such as fresh fish, meat, fruits and vegetables, tofu, prepared foods, etc., containers for dairy products such as milk, yogurt, lactic acid bacteria drinks, etc. used in the fresh fish market Used for transportation of carbonated beverages, soft drinks, liquor drinks such as beer and whiskey, cosmetics containers, detergent containers, bleach containers, cool boxes, flower pots, tapes, home appliances such as TVs and stereos. Cushioning materials and packaging materials, cushioning materials for transportation of precision machines such as computers, printers and watches, and optical machines such as cameras, glasses, microscopes, and telescopes. Shock absorber, loose cushioning material (easy packing material that can be packed at the site), light shielding material, heat insulating material (extruded board etc.), soundproofing / sound insulating material (extruded board etc.), extruded foam sheet (Food related polymer paper, pre-packaged, mainly applied to food packaging and containers),
It can also be suitably used as a non-foamed film bonded to a foamed sheet, a filter for filtering sewage, a net-like foam, a foamed product, and the like.

General Industrial Use and Recreational Use The foamed product obtained by the present invention is suitable for general industrial use including agriculture, fishing, forestry, industry, construction and civil engineering, transport and transportation, and recreational use including leisure and sports. Can be used. For example, cold gauze for agriculture,
Oil absorbing material, soft ground reinforcement, artificial leather, floppy disk lining, sandbag bag, heat insulating material, soundproofing material, cushioning material, cushioning material for beds and chairs, floor cushioning material, packaging material, binding material It can be suitably used as a non-slip material for muddy or snowy roads.

[0060]

The present invention will be described in detail with reference to the following examples, but it should not be construed that the invention is limited thereto without departing from the technical scope of the present invention. The weight average molecular weight (Mw) of the polylactic acid-based resin, the cell diameter in the examples, the average cell diameter, the dispersion of the cell diameter, and the melt tension were measured by the following methods.

Weight average molecular weight (Mw) Measured by gel permeation chromatography (GPC) using a polystyrene as a standard and a column temperature of 40 ° C. in a chloroform solvent.

Cell Diameter, Average Cell Diameter The equivalent layer diameter of a cell in 100 mm × 80 mm in a photograph (50 ×) of the inner layer portion of the cross section of the obtained foamed sheet taken by an optical microscope was calculated and defined as the cell diameter. . The average cell diameter is an average value of cells in 100 mm × 80 mm in the above photograph. Most cells in the present invention have a cell diameter of 10
In the present invention, cells having a size of 0 μm or more and less than 100 μm occupy a very small percentage of the whole and are ignored.

Cell Diameter Variation Judgment was made from the difference between the maximum cell diameter and the minimum cell diameter in the same photograph.・ ・ ・: Aligned (difference is within 500 μm) △: Slightly varied (difference is 500 to 1000 μm)
m) × ・ ・ ・ There is variation (the difference is 1000 μm or more)

Melt tension (MT value) After measuring the melt flow index at two appropriate temperatures using a load of 2160 g, the temperature-melt flow index-plot was used to determine the temperature at which the melt flow index was 10 g / 10 min. The melt tension was measured at that temperature.

Production Example 1 In a reactor equipped with a Dien-Stark trap, 9
8.93 kg of 0% L-lactic acid, weight average molecular weight (Mw) 3
10,000, 0.19 kg of acetylcellulose with a substitution degree of 1.5,
After charging 45 g of tin dust and distilling water while stirring at 150 ° C./50 mmHg for 3 hours, 150 ° C./30 mmHg
g was further stirred for 2 hours to oligomerize. 21.1 kg of diphenyl ether is added to this oligomer, and 15
An azeotropic dehydration reaction at 0 ° C./35 mmHg was performed, and 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 filled with 4.6 kg of molecular sieve 3A, and then returned to the reactor. The reaction was carried out at 130 ° C./17 mmHg for 20 hours, and the weight average molecular weight (Mw) was obtained. 73,000 degradable copolymers were obtained. 44 kg of dehydrated diphenyl ether was added to this solution for dilution, and then cooled to 40 ° C.
The precipitated crystals were filtered. 0.5N HCl
12 kg and 12 kg of ethanol were added, and the mixture was stirred at 35 ° C. for 1 hour, filtered, dried at 60 ° C./50 mmHg,
6.3 kg of polylactic acid-based decomposable copolymer powder was obtained. This powder was melted and pelletized by an extruder to obtain a polylactic acid-based resin. The weight average molecular weight (Mw) of this polymer was 69.
It was 50,000. The melt tension was 11.0 g.

Production Example 2 In a reactor equipped with a Dien-Stark trap, 9
8.93 kg of 0% L-lactic acid, weight average molecular weight (Mw)
67,000, 0.19k of ethyl cellulose with a degree of substitution of 1.9
g, tin powder 45 g, 150 ° C./50 mmHg 3
After distilling water while stirring for 150 hours, 150 ° C / 30m
The mixture was further stirred for 2 hours at mHg to be oligomerized. To this oligomer was added 21.1 kg of diphenyl ether,
An azeotropic dehydration reaction at 150 ° C./35 mmHg was performed, and 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 filled with 4.6 kg of molecular sieve 3A, and then returned to the reactor. The reaction was carried out at 130 ° C./17 mmHg for 20 hours, and the weight average molecular weight (Mw) was obtained. 73,000 degradable copolymers were obtained. 44 kg of dehydrated diphenyl ether was added to this solution to dilute it, and then cooled to 40 ° C., and the precipitated crystals were filtered. 0.5N-H
Add 12 kg of Cl and 12 kg of ethanol.
After stirring for an hour, the mixture was filtered and dried at 60 ° C./50 mmHg to obtain 5.9 kg of a polylactic acid-based decomposable copolymer powder.
This powder was melted and pelletized by an extruder to obtain a polylactic acid-based resin. The weight average molecular weight (Mw) of this polymer is 3
It was 50000. The melt tension was 13.0 g.

Production Example 3 9 reactor was equipped with a Dien-Stark trap.
10 kg of 0% L-lactic acid and 45 g of tin powder are charged, and 150 ° C.
After distilling water while stirring at / 50 mmHg for 3 hours, the mixture was stirred at 150 ° C / 30 mmHg for 2 hours to oligomerize. 21.1 kg of diphenyl ether was added to this oligomer, and an azeotropic dehydration reaction at 150 ° C./35 mmHg was performed. 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 carried out at 17 mmHg for 20 hours to obtain a polylactic acid solution having a weight average molecular weight (Mw) of 150,000. 44 kg of dehydrated diphenyl ether was added to this solution to dilute it, and then cooled to 40 ° C., and the precipitated crystals were filtered. 12 kg of 0.5 N HCl and 12 k of ethanol
g, and the mixture was stirred at 35 ° C. for 1 hour, and then filtered.
Drying at 50 mmHg yielded 6.1 kg of polylactic acid powder (85% yield). This powder was melted and pelletized by an extruder to obtain polylactic acid. The weight average molecular weight (Mw) of this polymer was 1470,000. The melt tension was 0.6 g.

Example 1 To 100 parts by weight of the polylactic acid-based resin obtained in Production Example 1, calcium stearate as a foaming aid and talc as an inorganic filler foaming nucleating agent were mixed with a Henschel mixer, and the mixture was extruded with a φ50 mm single screw. A machine (manufactured by Frontier) and a screw were subjected to foam extrusion molding using a full-flight type L / D = 30, T-die having a width of 650 mm and a land length of 10 mm while injecting carbon dioxide as a volatile foaming agent. Cylinder temperature is 170-180 ° C, temperature near gas leakage prevention ring is 180 ° C, T-die temperature is 140 ° C
I went in. The resin kneaded material was discharged into the atmosphere from the slit to obtain a foamed sheet having a width of 650 mm. The foaming ratio of the obtained sheet was 13.0, the cell diameter was 100 to 500 μm, and the cell diameter was good without any variation. The raw materials used in the experiment are as follows. Talc 1 ... microace L-1 (manufactured by Nippon Talc) talc 2 ... NK48 (manufactured by Fuji Talc) calcium stearate ... calcium montanate manufactured by NOF Corporation・ Hoechst

Examples 2 to 5 As shown in Table 1 [Table 1], a polylactic acid-based resin, a foaming aid, and a nucleating agent were mixed using a Henschel mixer and the same as in Example 1 while injecting carbon dioxide. The experiment was performed. The results are summarized in Table 1 [Table 1].

Comparative Examples 1 to 7 As shown in Table 1 [Table 1] and Table 2 [Table 2], a polylactic acid resin, a foaming aid, and a nucleating agent were mixed using a Henschel mixer, and carbon dioxide was removed. An experiment was performed in the same manner as in Example 1 while injecting. The results are shown in Table-1 [Table 1] and Table-2.
Table 2 summarizes the results.

[0071]

[Table 1] [Legend] “←”; “Same on the left. ] Means.

[0072]

[Table 2] [Legend] “←”; “Same on the left. ] Means.

[0073]

According to the composition for producing a polylactic acid-based resin foam of the present invention, a molded article having a uniform cell diameter can be obtained. The obtained molded article and sheet have improved foam moldability as compared with conventional polylactic acid.

Continued on the front page (72) Inventor Takayuki Watanabe 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsui Chemical Co., Ltd. Person Tomoyuki Nakata 1190 Kasama-cho, Sakae-ku, Yokohama City, Kanagawa Prefecture F-term (reference) 4F074 AA68 AB01 AB05 AD10 AE01 BA31 BA32 BC12 CC22X DA03 DA33 DA34 DA43 DA55 DA58 4F208 AA24 AB02 AB16 AB19 AE10 AG01 AG20 MA01 MA03 MB01 MG13 4J002 AB011 AB021 AB031 AB051 AE042 CF181 CF191 DE018 DE028 DE076 DE146 DE236 DJ006 DJ016 DJ036 DJ046 EA018 EA028 EB028 EB068 EF057 EG037 EG047 FD202 FD206 FD207 FD328

Claims (17)

[Claims] (1) Polysaccharide (A) and (b1) lactic acid,
(B2) at least one selected from the group consisting of polylactic acid
With respect to 100 parts by weight of the decomposable copolymer having a melt tension in the range of 0.7 to 20 g at a melt flow index of 10 g / 10 minutes obtained by subjecting the seed (B) to a dehydration polycondensation reaction, at least (2) 0.1) to 5.0 parts by weight of an inorganic filler foam nucleating agent having an average particle size of 1 to 10 μm;
(3) 0.01 to 0.5 parts by weight of a foaming aid, and (4) 0.1 to 20 parts by weight of a volatile foaming agent.
A composition for producing a polylactic acid-based foam. 2. The composition for producing a polylactic acid-based foam according to claim 1, wherein the inorganic filler foam nucleating agent is talc, and the foaming aid is a stearic acid-based compound and / or a montanic acid-based compound. 3. The composition for producing a polylactic acid-based foam according to claim 1, wherein the polysaccharide is acetyl cellulose and / or ethyl cellulose. 4. A polylactic acid-based foam obtained by melt-kneading the composition according to any one of claims 1 to 3. 5. A polylactic acid-based foamed sheet obtained by melt-kneading the composition according to any one of claims 1 to 3. 6. A method for producing a polylactic acid-based foam, comprising melt-kneading the composition according to claim 1 to obtain a foam. 7. A foamed sheet obtained by melting and kneading the composition according to any one of claims 1 to 3.
A method for producing a polylactic acid-based foam sheet. 8. A polylactic acid-based molded article obtained by subjecting the foamed sheet according to claim 5 to a molding method of vacuum molding or vacuum pressure molding. 9. A polysaccharide (A), (b1) lactic acid,
(B2) at least one selected from the group consisting of polylactic acid
With respect to 100 parts by weight of the decomposable copolymer having a melt tension in the range of 0.7 to 20 g at a melt flow index of 10 g / 10 minutes obtained by subjecting the seed (B) to a dehydration polycondensation reaction, at least (2) 0.1) to 5.0 parts by weight of an inorganic filler foam nucleating agent having an average particle size of 1 to 10 μm;
(3) When melt molding a resin composition comprising 0.01 to 0.5 parts by weight of a foaming aid, (4) a volatile foaming agent of 0.1 to 0.5 parts by weight.
A method for producing a polylactic acid-based foam, comprising adding 20 parts by weight and foaming. 10. A melt obtained by a dehydration polycondensation reaction between (1) a polysaccharide (A) and at least one kind (B) selected from the group consisting of (b1) lactic acid and (b2) polylactic acid. With respect to 100 parts by weight of the degradable copolymer having a melt index in the range of 0.7 to 20 g at a flow index of 10 g / 10 min, at least (2) the average particle size is 1 to 10 μm.
0.1 to 5.0 parts by weight of an inorganic filler foam nucleating agent,
(3) When melt molding a resin composition comprising 0.01 to 0.5 parts by weight of a foaming aid, (4) a volatile foaming agent of 0.1 to 0.5 parts by weight.
A method for producing a polylactic acid-based foam sheet, comprising adding 20 parts by weight and foaming. 11. The method for producing a polylactic acid-based foam according to claim 9, wherein the inorganic filler foam nucleating agent is talc, and the foaming aid is a stearic acid-based compound and / or a montanic acid-based compound. 12. The method for producing a polylactic acid-based foam according to claim 9, wherein the polysaccharide is acetyl cellulose and / or ethyl cellulose. 13. The method for producing a polylactic acid-based foamed sheet according to claim 10, wherein the inorganic filler foam nucleating agent is talc, and the foaming aid is a stearic acid-based compound or a montanic acid-based compound. 14. The method according to claim 10, wherein the polysaccharide is acetylcellulose and / or ethylcellulose. 15. A polylactic acid-based foam obtained by the method according to any one of claims 9 to 14. 16. A polylactic acid-based foamed sheet obtained by the method according to any one of claims 9 to 14. 17. A polylactic acid-based molded article obtained by subjecting the foamed sheet according to claim 16 to a molding method of vacuum molding or vacuum pressure molding.