JP2000355089A - Biodegradable polymer laminate or container provided with conductivity - Google Patents

Abstract

(57) [Problem] To solve the problem to be solved by the present invention is a conductive lactic acid-based polymer laminate having practical conductivity, biodegradability, good appearance, rigidity, impact resistance, and heat workability. An object of the present invention is to provide a body and a sheet or container comprising the laminate. SOLUTION: A lactic acid-based polymer containing 17 to 40% by weight of a conductivity-imparting agent is provided on at least one surface of a base layer (I) composed of a lactic acid-based polymer (A) containing 12% by weight or less of a conductivity-imparting agent. A conductive lactic acid-based polymer laminate having a surface resistance value of 10 ¹⁰ Ω or less on the side of the conductivity-imparting layer (II) on which the conductivity-imparting layer (II) made of the polymer (B) is formed, and the laminate Sheet or container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive lactic acid-based polymer laminate containing a conductivity-imparting agent such as carbon black produced by an extrusion molding method or the like. % Secant modulus), excellent strength such as impact resistance, pressure forming, vacuum forming,
The present invention relates to a biodegradable conductive lactic acid-based polymer laminate having good thermoformability according to press molding and the like and having practical conductivity even after molding. The molded container produced by thermoforming the conductive lactic acid-based polymer laminate can be suitably used for trays, carrier tapes and the like of electronic parts, industrial parts and the like.

[0002]

2. Description of the Related Art Conventionally, in the field of packaging of electronic parts and industrial parts, the material of a sheet or a container formed by molding the sheet, which is required to have conductivity, has various properties due to its good heat workability and light weight. A resin obtained by adding a conductivity-imparting agent such as carbon black to a plastic resin is used. Since these thermoplastic resins are required to have balanced rigidity and impact resistance, polypropylene resin (PP), polyvinyl chloride resin (PVC), high impact polystyrene resin (HIPS) or acrylonitrile Butadiene-styrene copolymer resin (ABS) and the like are used.

[0003] These thermoplastic resins are carbon black,
Conductivity is exhibited by containing a conductivity-imparting agent such as carbon fiber, fine powder of metal or metal oxide, fiber, and whisker. The thermoplastic resin containing the conductivity-imparting agent is processed into a sheet having a certain thickness by extrusion molding or the like. The sheet is formed into a conductive container by thermoforming such as vacuum forming, air forming or press forming, and is used for various electronic components and industrial parts as a conductive tray, carrier tape and the like.

Although these molded articles are often discarded after a single use, these thermoplastic resins have a high chemical stability, so that they do not decompose and remain semi-permanently in their original form. Since it remains, its disposal has caused environmental problems. When discarded in a natural environment without care, the appearance is impaired, marine organisms, birds, and the like are erroneously eaten, leading to a decrease in valuable biological resources. Recently, biodegradable polymers have been actively studied to solve these environmental problems.

[0005] Biodegradable polymers readily degrade in the natural environment, eventually resulting in water and carbon dioxide. In addition, since it has a low calorie burn, it does not hurt the furnace even when incinerated, and does not generate harmful gas during combustion. In addition, it is an environmentally circulating polymer that is easy to regenerate as a starting material. From these advantages, it is expected as a substitute for the thermoplastic resin derived from petroleum resources which has been conventionally used.

Japanese Unexamined Patent Publication No. 9-263690 describes a plastic composition having conductivity and biodegradability, but the balance between conductivity and strength suitable for thermoforming is not always sufficient.

[0007]

The problems to be solved by the present invention are practical conductivity, biodegradability, good appearance,
It is an object of the present invention to provide a conductive lactic acid-based polymer laminate having rigidity, impact resistance, and heat workability, and a sheet or container made of the laminate.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the problems and found that at least one surface of a substrate layer made of a lactic acid-based polymer containing 12% by weight or less of a conductivity-imparting agent. Having a conductivity-imparting layer made of a lactic acid-based polymer containing 17 to 40% by weight of a conductivity-imparting agent, has a good balance between conductivity and strength suitable for thermoforming. The present inventors have found that a polymer laminate can be obtained, and have completed the present invention.

That is, the present invention relates to (1) a base layer (I) comprising a lactic acid-based polymer (A) containing 12% by weight or less of a conductivity-imparting agent, on at least one surface of which 17% to 40% by weight of A conductive lactic acid-based polymer laminate having a conductivity-imparting layer (II) comprising a lactic acid-based polymer (B) containing a conductivity-imparting agent and having a surface resistance value of 10 ¹⁰ Ω or less on the side of the conductivity-imparting layer (II). Body and

(2) The conductive lactic acid-based polymer laminate according to (1), wherein the lactic acid-based polymer (A) and / or the lactic acid-based polymer (B) is polylactic acid;

(3) A lactic acid-based polymer (A) and / or a lactic acid-based polymer (B) is a polyester structural unit obtained by dehydration-condensation of a dicarboxylic acid and a diol and / or a polyether obtained by dehydration-condensation of a dicarboxylic acid and a polyether polyol. A conductive lactic acid-based polymer laminate according to (1), which is a lactic acid-based polymer containing 3 to 40% by weight of a structural unit;

(4) Thickness D (II) of conductivity imparting layer (II)
And the ratio of the thickness D (I) of the base material layer (I) is D (II) / D
(I) the conductive lactic acid-based polymer laminate according to any one of (1) to (3), wherein 0.03 to 0.8;

(5) Lactic acid-based polymers (A) and (B) are lactic acid-based polymers whose molecular weight has been increased by adding a high-molecular-weight agent such as polyvalent carboxylic acid, acid anhydride or polyvalent isocyanate. 1) to the conductive lactic acid-based polymer laminate according to any one of (4),

(6) The lactic acid-based polymer (A) or (B) is a lactic acid-based polymer in which the polymerization catalyst is deactivated by a deactivator of the polymerization catalyst, or the residual monomer is reduced by devolatilization or reprecipitation. A conductive lactic acid-based polymer laminate according to any one of (1) to (4),

(7) 1% Secant Modulus is 1.2
The conductive lactic acid-based polymer laminate according to any one of (1) to (4), which has GPa or more;

(8) Any one of the above (1) to (7)
A sheet extruded from the conductive lactic acid-based polymer laminate according to

(9) Any one of the above (1) to (7)
And a container obtained by thermoforming the conductive lactic acid-based polymer laminate described in (1).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in detail. In the present invention, 17 to 40% by weight of a conductivity-imparting agent is contained on at least one surface of a base layer (I) composed of a lactic acid-based polymer (A) containing 12% by weight or less of a conductivity-imparting agent. A conductive lactic acid-based polymer laminate having a conductivity-imparting layer (II) made of a lactic acid-based polymer (B) formed thereon, a sheet comprising the laminate, or a container obtained by thermoforming the laminate.

Considering the practical impact resistance of the conductive lactic acid-based polymer laminate, the lactic acid-based polymer of the base layer (I)
The content of the conductivity-imparting agent in (A) must be 12% by weight or less. Interestingly, a lactic acid-based polymer containing 1 to 12% by weight of carbon black as a conductivity-imparting agent
(A) has the effect of improving the impact resistance and improving the impact resistance of the laminate. However, if the content of the conductivity-imparting agent in the lactic acid-based polymer (A) exceeds 12% by weight, the impact resistance of the conductive lactic acid-based polymer laminate rapidly decreases.

Therefore, the content of the conductivity-imparting agent in the lactic acid-based polymer (A) constituting the base layer (I) of the conductive lactic acid-based polymer laminate of the present invention is 12% by weight or less, The lactic acid-based polymer (A) of the layer (I) that does not contain a conductivity-imparting agent is also included in the present invention. However, the amount of the conductivity-imparting agent in the lactic acid-based polymer (A) is more preferably 2 to 10% by weight, and still more preferably 3 to 10% by weight, from the viewpoint of improving the impact resistance of the laminate.

In order to have sufficient conductivity to protect the electronic components from static electricity or to remove dust, the surface resistance of the thermoformed conductive lactic acid-based polymer laminate on the side of the conductivity-imparting layer must be 10%. Must be ¹⁰ Ω or less. Further, the conductive lactic acid-based polymer laminate after the molding process tends to have lower conductivity than before the molding. In order to impart sufficient conductivity to the molded product, the surface resistance of the conductivity-imparting layer should be 10
^In order to reduce the resistance to ¹⁰ Ω or less and maintain good thermoformability, the conductivity-imparting layer (II) composed of the lactic acid-based polymer (B) is required.
The content of the conductivity-imparting agent contained in 17% by weight or more,
It needs to be 40% by weight or less.

If the content is less than 17% by weight, the conductive lactic acid-based polymer laminate after thermoforming does not exhibit effective conductivity for use as a conductive tray. If it exceeds 40% by weight, the lactic acid-based polymer (B) has poor elongation during thermoforming, and the moldability of the lactic acid-based conductive lactic acid-based polymer laminate deteriorates. In addition, the conductivity-imparting agent is remarkably dropped off due to friction or the like, and the usability becomes extremely poor. Therefore, the content of the conductivity-imparting agent in the conductivity-imparting layer (II) composed of the lactic acid-based polymer (B) is 1
The content is 7 to 40% by weight, more preferably 17 to 35% by weight, and still more preferably 20 to 30% by weight.

In order to evaluate the moldability of the lactic acid-based conductive lactic acid-based polymer laminate of the present invention, it is necessary to evaluate various physical property values.
There is a 1% secant modulus value using a tensile tester. The 1% secant modulus value of the conductive lactic acid-based polymer laminate sheet needs to be 1.2 GPa or more. 1%
The measurement of the secant modulus value is performed according to JIS K-7127.
Corresponds to the measurement of the tensile secant modulus at 1% strain.

As a scale for judging the superiority of impact resistance,
There is a DuPont impact strength measurement method in which a weight having a constant weight is dropped at different heights to obtain a 50% breaking energy. In the measurement, the impact value of the conductive lactic acid-based polymer laminate sheet is preferably 0.1 J or more.

Considering the conductivity and impact resistance of the conductive lactic acid-based polymer laminate, the thickness D (II) of the conductivity-imparting layer (II) formed on the surface of the base material layer (I) and the thickness The layer composition ratio of the thickness D (I) of the material layer (I) is D (II) / D (I) = 0.0
Must be between 3 and 0.8. If it is less than 0.03, the conductive tray or the like after thermoforming of the conductive lactic acid-based polymer laminate does not exhibit effective conductivity. If it exceeds 0.8, the impact resistance of the conductive lactic acid-based polymer laminate becomes poor, which is not practical.
More preferably, D (II) / D (I) = 0.03 to 0.7.
And more preferably 0.05 to 0.6.

The conductivity-imparting agent contained in the lactic acid-based polymers (B) and (A) is selected from carbon black, carbon fiber, fine powder of metal or metal oxide, fiber, and whisker. These may be used alone or in combination. Among them, carbon black is more excellent in expressing conductivity.
Carbon fiber, more preferably carbon black.

With respect to conductivity, it is preferable that carbon black has a large specific surface area and a small particle size. However, considering mechanical properties, a specific surface area of 10 to 300 m ² / g and a particle size of 10 to 100 nm are appropriate.

The lactic acid-based polymer used in the present invention is a polylactic acid or a structural unit obtained by dehydrating and condensing polylactic acid or lactic acid.
A lactic acid-based polymer containing a polyester structural unit obtained by dehydrating and condensing a dicarboxylic acid component and a diol component and / or a polyether structural unit obtained by dehydrating and condensing a dicarboxylic acid and a polyether polyol component, and a mixture thereof.

When the ratio of the polyester structural unit and / or the polyether structural unit in the lactic acid-based polymer is large, the impact resistance of the lactic acid-based polymer is improved, and the impact resistance of the conductive lactic acid-based polymer laminate is improved. Can be. But,
When the amount of the polyester structural unit and / or the polyether structural unit exceeds 40% by weight, the rigidity of the laminate decreases, and it becomes difficult to support the contents. Therefore, the proportion of the polyester structural unit and / or polyether structural unit in the lactic acid-based polymer is preferably 40% by weight or less, more preferably 3 to 4%.
0% by weight.

Carbon black is added to the lactic acid-based polymer.
By containing 12% by weight, the impact resistance can be further improved without lowering the rigidity (1% secant modulus). In particular, the impact resistance is remarkably improved by adding 1 to 12% by weight of carbon black to a lactic acid-based polymer containing a polyester structural unit obtained by dehydrating and condensing a dicarboxylic acid component and a diol component in a structural unit obtained by dehydrating and condensing polylactic acid or lactic acid. Can be improved.

The impact resistance is further improved by increasing the molecular weight of the lactic acid-based polymer. From this viewpoint, the weight average molecular weight of the lactic acid-based polymer used in the present invention is from 50,000 to 50
About 10,000 is appropriate, and more preferably 70,000 to 450,000. If it is less than 50,000, the mechanical properties are inferior and impractical.
If it exceeds 10,000, the resulting conductive lactic acid-based polymer laminate becomes inferior in heat workability, which is not preferable.

The lactic acid component used in the lactic acid-based polymer is L-, D-, DL-lactic acid, which is an optical isomer, and the dicarboxylic acid component is, for example, adipic acid, sebacic acid, succinic acid, dimer acid, or the like. No. Examples of the diol component include those having 2 to 6 carbon atoms in the main chain, such as ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, and 1,6-hexanediol.

Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polybutylene glycol and the like. Among these, it is most preferable to use adipic acid, sebacic acid, and dimer acid as the dicarboxylic acid component, propylene glycol as the diol component, and polypropylene glycol as the polyether polyol component.

As a method for producing polylactic acid, a method of obtaining a high molecular weight polylactic acid by ring-opening polymerization of lactide, which is a cyclic dimer of lactic acid, is often used. Is also used.
Further, the copolymer of the lactic acid-based polymer is added with one or more of aliphatic polyester, aromatic polyester, caprolactone, vinyl acetate, ethylene terephthalate polymer, ethylene vinyl alcohol and the like at the time of or immediately after the polymerization of polylactic acid, and the polymerization is further advanced. It can be obtained by:

Although any stage of these polymerization reactions may be used, the addition of a polycarboxylic acid and / or a high molecular weight agent such as an oxide anhydride thereof or a polyvalent isocyanate makes it possible to further increase the lactic acid-based polymer if necessary. It can be made molecular weight. Examples of the polycarboxylic acid include trimellitic acid and pyromellitic acid, and examples of the oxide anhydride include succinic anhydride, trimellitic anhydride, and pyromellitic anhydride.

As the polyvalent isocyanate, 2,4-
Tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, And triphenylmethane-4,4 ', 4 "-triisocyanate.

The amount of the high molecular weight agent to be added may be about 0.01 to 5% by weight based on the lactic acid-based polymer. Usually, the weight average molecular weight of about 300,000 is increased to about 600,000 to 700,000. Can be. A conductive lactic acid-based polymer laminate using a high-molecular-weight lactic acid-based polymer is preferable because the impact resistance is improved. In particular, when the base layer (I) composed of the high molecular weight lactic acid-based polymer (B) contains 1 to 12% by weight of carbon black, a higher impact resistance improving effect can be obtained.

Further, a chelating agent and an acid phosphate are added as deactivators of the polymer polymerization catalyst during and / or after the completion of the polymerization of the polymer.
Thermal stability and storage stability of the polymer can be greatly improved. They form a complex with a metal ion of a polymerization catalyst contained in a lactic acid-based polymer and lose catalytic activity.

As the chelating agent used, there are an organic chelating agent and an inorganic chelating agent. Organic chelating agents include, but are not limited to, amino acids, phenols, hydroxycarboxylic acids, diketones, amines,
Oximes, phenanthrolines, pyridine compounds, dithio compounds, N-containing phenols as coordinating atoms, N-containing carboxylic acids as coordinating atoms, diazo compounds, thiols,
And porphyrins.

The inorganic chelating agent has a high hygroscopic property, and if it absorbs moisture, its effect is lost. Specific examples include phosphoric acids such as phosphoric acid, phosphorous acid, pyrophosphoric acid, and polyphosphoric acid. Further, a mixture of an organic chelating agent and an inorganic chelating agent may be used.

The amount of the organic chelating agent or the inorganic chelating agent to be added depends on the type and amount of the lactic acid component and the polymerization catalyst contained in the lactic acid-based polymer comprising the dicarboxylic acid component and the diol component. But,
The lactic acid component or the lactic acid component, and the lactic acid-based polymer composed of the dicarboxylic acid component and the diol component is 0.00
It is preferable to add 1 to 5 parts by weight, or 0.1 to 100 parts by weight based on 1 part by weight of the used catalyst.

The acidic phosphoric acid esters include acidic phosphoric acid esters, phosphonic acid esters, alkylphosphonic acids, and the like, and mixtures thereof.

[0043]

Embedded image

(In the formula, R1 represents an alkyl group or an alkoxyl group, and R2 represents an alkyl group, an alkoxyl group, or a hydroxyl group.) Among the acidic phosphoric acid esters, the acidic phosphoric acid ester is particularly effective in deactivating the catalyst. . The amount of the acidic phosphoric acid ester varies depending on the type thereof, the type of the catalyst used, and the kneading conditions. It is preferable to add 0.1 to 100 parts by weight to 1 to 5 parts by weight or 1 part by weight of the used catalyst.

The lactic acid-based polymer (A) and / or the lactic acid-based polymer (B) used in the present invention may be a lactic acid-based polymer in which the polymerization catalyst has been deactivated by a polymerization catalyst deactivator and / or devolatilization and / or regeneration. It is preferable that the lactic acid-based polymer has a residual monomer reduced by precipitation.

After the polymerization of the lactic acid-based polymer, the polymerization catalyst is deactivated by a deactivator or devolatilized or re-precipitated to reduce the residual monomer or oligomer, thereby promoting the residual monomer or oligomer. Lactic acid-based polymer is prevented from decomposing to improve the storage stability of the polymer, and furthermore, by preventing residual monomers and oligomers from being precipitated and deposited on a cooling roll or a forming die during extrusion molding, the conductive lactic acid-based polymer is prevented. The appearance of the polymer laminate sheet can be prevented from being impaired.

The lactic acid-based polymer (A) and / or lactic acid-based polymer (B) used in the conductive lactic acid-based polymer laminate of the present invention can be prepared by deactivating a polymerization catalyst with a deactivator after polymerization of the lactic acid-based polymer. By devolatilizing and / or reprecipitating, the residual monomer and oligomer content is 2% by weight or less, more preferably 1% by weight or less, further preferably,
It is preferable to use one having a content of 0.1% by weight or less.

In addition to deactivating the polymerization catalyst with the deactivator of the polymerization catalyst, there is a devolatilization method of heating and devolatilizing the lactic acid-based polymer under reduced pressure as a method for physically reducing the residual monomers and oligomers. Concrete devolatilization is performed by a single-screw or twin-screw extruder, a thin-film evaporator, a pot-type decompression device, or the like.

For the devolatilization, it is preferable to take out the lactic acid-based polymer while heating under reduced pressure after the polymerization. The devolatilization conditions for not lowering the molecular weight of the lactic acid-based polymer are as follows: devolatilization time is 10 seconds to 10 minutes, temperature is 100 to 230 ° C., degree of reduced pressure is 0.1 to 50 Torr, more preferably 0.1 to 1 Torr.
0 Torr, and more preferably 0.1 to 5 Torr.

Further, there is a method in which after the polymerization is completed, the lactic acid-based copolymer is pelletized or pulverized, and is taken out while heating under reduced pressure. Also in this case, for the purpose of not lowering the molecular weight of the lactic acid-based polymer, the devolatilization time is 2 to 400 minutes, the temperature is 60 to 200 ° C., the degree of reduced pressure is 0.1 to 50 Torr, more preferably 0.1 to 10 Torr, and still more preferably. Is 0.1 to 5 Torr.

Further, after the polymerization, the lactic acid-based polymer is taken out, and a vent or the like is installed in the extruder when performing thermoforming into a film or sheet using a single-screw or twin-screw extruder. Even if devolatilization is performed, the same devolatilization effect can be obtained.
Also in this case, for the purpose of not lowering the molecular weight of the lactic acid-based polymer, the devolatilization time is 10 seconds to 10 minutes, and the temperature is 145 to 230.
° C, the degree of reduced pressure is 0.1 to 50 Torr, preferably 0.1
10 to 10 Torr, more preferably 0.1 to 5 Torr.

Further, there is a reprecipitation method in which a lactic acid-based polymer is dissolved in a solvent after completion of the polymerization reaction and added to a poor solvent to obtain a lactic acid-based polymer. Solvents that dissolve lactic acid-based polymers include benzene, toluene, ethylbenzene,
Xylene, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, methyl isobutyl ketone, methyl ethyl ketone, isopropyl ether, dichloromethane, chloroform,
Examples thereof include carbon tetrachloride, chlorobenzene, dichlorobenzene, trichlorobenzene, and chloronaphthalene.

These solvents may be used alone or as a mixture. Examples of the poor solvent include water, methanol, ethanol, propanol, butanol, pentane, octane, nonane, decane, diesil ether and the like, and a mixed solvent thereof. In the reprecipitation method, a lactic acid-based polymer having a concentration of 2 to 20% by weight is dissolved in a solvent at room temperature or while heating, and gradually added to a 2 to 15-fold amount of poor solvent with stirring, and left standing for 10 to 180 minutes. A precipitate is formed and removed. The removed precipitate removes residual solvent under reduced pressure and / or under heating.

The lactic acid-based polymer used in the present invention is preferably a lactic acid-based polymer in which residual monomers and oligomers have been reduced by any one of these methods. May be used.

The laminate according to the present invention has a thickness of 5000 μm.
Refers to the following plate-like ones. The lactic acid-based polymer of the conductive lactic acid-based polymer laminate of the present invention, as long as the expression of conductivity and the moldability are not impaired, as necessary, as the second and three components,
A small amount of other polymers such as polyvinyl alcohol, polyhydroxybutyrate-hydroxyvalerate, and starch-based polymers, and known and commonly used plasticizers, stabilizers, antioxidants, antiblocking agents, antifogging agents, coloring agents, and the like. An additive such as an agent may be included.

Examples of these additives include polyester plasticizers such as 1,3-butanediol and adipic acid, plasticizers such as dioctyl phthalate and polyethylene glycol adipic acid, and stable additives such as epoxidized soybean oil and carbodiimide. Agents, 2,6-di-tert-butyl-4-methylphenol (BHT), butyl hydroxyanisole (BH
Antioxidants such as A), antiblocking agents such as silica and talc, glycerin fatty acid esters, antifogging agents such as monostearyl citrate, titanium oxide, coloring agents such as ultramarine blue, stearic acid, oleic acid, Dispersants such as fatty acids of lauric acid and the like can be mentioned.

The conductive lactic acid-based polymer laminate of the present invention comprises:
At least one surface of a base layer (I) composed of a lactic acid-based polymer (A) containing not more than 12% by weight of a conductivity-imparting agent,
Lactic acid-based polymer containing up to 40% by weight of a conductivity-imparting agent
(B) formed with a conductivity imparting layer (II).

As the forming method, the most practical and efficient lamination of the base material layer (I) and the conductivity imparting layer (II) by coextrusion molding using two or more extruders. Other methods of melt-extruding and laminating the conductivity-imparting layer (II) or the substrate layer (I) on the preliminarily formed substrate layer (I) or the conductivity-imparting layer (II), respectively. (I) or the conductivity imparting layer (II) and the conductivity imparting layer (II) or the base material layer (I)
Are laminated via an adhesive.

As long as the performance is not hindered, a metal or metal oxide may be deposited on the surface of the conductive lactic acid-based polymer laminate, a printed surface may be formed, or a release of silicone or the like may be performed. Agent may be applied, or a conductive ink containing a conductivity-imparting agent such as carbon black may be applied. Further, two or more of these processes may be performed. The thickness of the conductive lactic acid-based polymer laminate is preferably from 5 to 5000 μm, and more preferably from 50 to 3000 μm from the viewpoint of strength and economy.

Next, a method of extruding a lactic acid-based polymer and its conditions will be described. Since lactic acid-based polymers have high hygroscopicity and strong hydrolyzability, it is necessary to control the water content.When extruding using a general single-screw extruder, make sure that dehydration is efficiently performed through the vent of the extruder. Alternatively, the polymer needs to be dehumidified and dried by a dehumidifying dryer or a vacuum dryer before film formation. Film formation by a vented twin-screw extruder has a high dewatering effect, and enables efficient film formation.

The melt extrusion temperature for forming the lactic acid-based polymer is not particularly limited, but is usually in the range of 150 to 250 ° C. The melt-extruded sheet is cast to a predetermined thickness, and is cooled if necessary. At this time, when the sheet is thick, a uniform sheet is obtained by using a touch roll and an air knife, and when the sheet is thin, using an electrostatic pinning. The interval between the lips for performing the melt extrusion is set to 0.2 to 5.0 mm, but is preferably set to 0.2 to 3.0 mm in consideration of the film forming property.

Next, the lamination method will be specifically described.
First, as a method for producing a lactic acid-based polymer laminate by coextrusion molding, the base material layer (I) and the conductivity-imparting layer (II) are melted and kneaded by separate extruders, and are fed in a T-die or before. The layers are stacked in a block or the like, and a film is formed through a T die. The extrusion method and conditions are basically the same as those described above.

At this time, in order to prevent the lactic acid-based polymer from absorbing moisture, it is desirable that the raw material supply port of the extruder be in an absolutely dry state or an environment in which nitrogen or the like is purged. Furthermore,
The addition of the conductivity-imparting agent to the lactic acid-based polymer (B) may be performed by blending with the lactic acid-based polymer in advance before extrusion molding, or at a desired mixing ratio into the raw material supply port of the extruder during extrusion molding. It may be carried out using a device capable of continuous compounding such as an auto feeder.

A more preferable method is to use a twin-screw extruder to improve dispersibility and handling in the lactic acid-based polymer.
Using a Banbury mixer or the like, a master badge is prepared by mixing a lactic acid-based polymer with a conductivity-imparting agent at a high concentration of about 50% by weight or more in advance. The master badge is added to a lactic acid-based polymer so that the desired concentration is obtained.

In the melt extrusion lamination, the conductivity imparting layer (II) or the base material guided from the extruder to the T-die for a laminator is added to the base material layer (I) or the conductivity imparting layer (II) fed by the feeding machine. This is a method in which the layer (I) and the layer (I) are bonded by a laminator and laminated. The extrusion method and conditions are basically the same as those described above.

When the adhesion to the substrate layer (I) or the conductivity-imparting layer (II) is poor, a corona discharge treatment is performed before the substrate layer (I) or the conductivity-imparting layer (II) is sent to the laminator. Adhesion is improved by chemical etching such as flame plasma treatment and chromic acid treatment, surface treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting, or by selecting an appropriate anchor coating agent. Performance can be improved. Since the lactic acid-based polymer according to the present invention is produced from two layers having the same or similar thermal properties, a molded article having a good appearance can be obtained even when extrusion molding is performed.

The conductive lactic acid-based polymer laminate of the present invention can be subjected to a stretching treatment at a temperature not lower than the glass transition point of the lactic acid-based polymer, if necessary, for the purpose of improving mechanical properties and the like. The stretching method is not particularly limited, but may be any of rolling, longitudinal uniaxial stretching, horizontal uniaxial stretching, simultaneous biaxial stretching, and sequential biaxial stretching immediately after melt-extruding the lactic acid-based polymer or after storage. Performed by

Next, the thermoforming of the conductive lactic acid-based polymer laminate into a container or the like will be described. As a method for forming the conductive lactic acid-based polymer laminate into a container such as a tray for packaging electronic parts and industrial parts, a commonly used method of forming into a mold using air pressure can be used. In particular,
Vacuum forming or vacuum press forming in which heating is performed indirectly using a heater such as an infrared or far infrared ray, and hot plate press forming in which a heater is brought into direct contact with a hot plate and heated.

When the sheet made of the conductive lactic acid-based polymer laminate is indirectly heated, the heater temperature is 300 to 55.
0 ° C. is appropriate. If the temperature is lower than 300 ° C., the sheet cannot be efficiently heated. If the temperature exceeds 550 ° C., the drawdown occurs rapidly, making it difficult to measure the timing of molding.
Molded articles tend to have uneven thickness variation. The temperature of a heating body such as a hot plate when directly heating is suitably 55 to 160 ° C.

If the temperature is lower than 55 ° C., the heat for forming the sheet cannot be obtained. If the temperature is higher than 160 ° C., the sheet tends to be fused to the heating body, impairing the appearance of the molded product, and furthermore, the molding becomes difficult due to the adhesion of the hot plate. Become. Since vacuum molding and vacuum pressure molding can use a guide to a mold called a plug, it is advantageous for stabilizing the shape of a deep container or the like.

In particular, in the vacuum press forming, an air pressure of 105 to 106 Pa can be used, so that forming with better mold reproducibility is possible. On the other hand, in hot plate pressure forming, since an object to be heated such as a sheet is heated by directly contacting the same, heating can be performed more uniformly than indirect heating. For this reason, the molding area can be increased, and a large number of molded articles can be produced efficiently.

Press molding is generally used for molding the carrier tape. In this method, molding is performed by matching a male mold with a female mold of metal or the like, and the indirect heating method is mainly used as a heating method. In the press molding, a hole for feeding may be continuously formed in a sheet to be formed. However, since the conductive lactic acid-based polymer laminate of the present invention has a good impact resistance, breakage at the time of forming a hole may be caused. And a good molded state can be obtained.

The conductive lactic acid-based polymer laminate of the present invention is suitable for storing or packaging electronic parts, industrial parts, etc. by any of the molding methods described above. A molded container can be obtained. The method for producing a molded container comprising the conductive lactic acid-based polymer laminate of the present invention is not particularly limited to these thermoforming methods.
By using the conductive lactic acid-based polymer laminate according to the present invention, it is possible to obtain a biodegradable molded container suitable for storing or packaging electronic components and industrial components.

[0074]

EXAMPLES The present invention will be described in detail with reference to examples. First, a method for producing the lactic acid-based polymer used in the present invention will be described.

(Preparation of lactic acid-based polymer) Aliphatic polyester (weight average molecular weight: 35,000 (GPC, in terms of polystyrene), sebacic acid 50 mol%, 1,6 hexanediol 20 mol%, ethylene glycol 20 mol% ,
97 parts by weight of lactide (99 mol% of L-lactide, 1 mol% of D-lactide) were added to 3 parts by weight of 1,3 butanediol (10%), and the atmosphere was replaced with an inert gas. After mixing, 0.02 parts by weight of tin octoate was added as an esterification catalyst, and the mixture was reacted for 8 hours.

Thereafter, 0.04 parts by weight of an acidic phosphoric acid ester as a deactivator was added and kneaded. Further, devolatilization was carried out under heating and reduced pressure by a twin screw extruder. The conditions for devolatilization are as follows:
For 20 seconds, the temperature is 200 ° C., and the degree of reduced pressure is 5 Torr.
The obtained lactic acid-based polymer was a colorless and transparent resin, and the weight-average molecular weight was 200,000 as measured by GPC. This polymer is called P1.

Aliphatic polyester (weight average molecular weight:
35,000 (GPC, polystyrene equivalent), sebacic acid 5
0 mol%, 1,6 hexanediol 20 mol%, ethylene glycol 20 mol%, 1,3 butanediol 10
%) 30 parts by weight and 70 parts by weight of lactide (98 mol% of L-lactide, 2 mol% of D-lactide),
The atmosphere was replaced with an inert gas, the mixture was mixed at 170 ° C. for 1 hour, and 0.02 parts by weight of tin octoate was added as an esterification catalyst, followed by a reaction for 8 hours.

Thereafter, 0.04 parts by weight of an acidic phosphoric acid ester as a deactivator was added and kneaded. Further, devolatilization was carried out under heating and reduced pressure by a twin screw extruder. The conditions for devolatilization are as follows:
For 20 seconds, the temperature is 200 ° C., and the degree of reduced pressure is 5 Torr.
The obtained lactic acid-based polymer was a colorless and transparent resin, and the weight average molecular weight was 140,000 based on the result of GPC measurement. This polymer is called P2.

Aliphatic polyester (weight average molecular weight:
650,000 (GPC, polystyrene equivalent), dimer acid 5
0 mol%, 50 mol% of propylene glycol) and 20 parts by weight of lactide (96 mol% of L-lactide, 4 mol% of D-lactide) were added, and the atmosphere was replaced with an inert gas. The mixture was mixed for 1 hour, and 0.02 parts by weight of tin octoate was added as an esterification catalyst, followed by a reaction for 8 hours.

Thereafter, 0.04 parts by weight of an acidic phosphoric acid ester as a deactivator was added and kneaded. Further, devolatilization was carried out under heating and reduced pressure by a twin screw extruder. The conditions for devolatilization are as follows:
For 20 seconds, the temperature is 200 ° C., and the degree of reduced pressure is 5 Torr.
The obtained lactic acid-based polymer was a transparent resin, and the weight-average molecular weight was 1370,000 as measured by GPC. This polymer is called P3.

Aliphatic polyester (weight average molecular weight:
34,000 (GPC, polystyrene equivalent), sebacic acid 5
0 mol%, ethylene glycol 25 mol%, 1,6 hexanediol 25 mol%) 40 parts by weight of lactide (L
-97 mol% of lactide, 3 mol% of D-lactide) 6
0 parts by weight, and the atmosphere was replaced with an inert gas.
The mixture was mixed at 65 ° C. for 1 hour, and 0.02 parts by weight of tin octoate was added as an esterification catalyst, followed by a reaction for 8 hours.

Thereafter, 0.04 parts by weight of an acidic phosphoric acid ester as a deactivator was added and kneaded. After the completion of the combined reaction, reprecipitation was performed using tetrahydrofuran as a solvent and methanol as a poor solvent. The obtained lactic acid-based polymer (A) was a colorless and transparent resin, and the weight average molecular weight was 102,000 based on the result of GPC. This polymer is called P4.

The atmosphere was replaced with an inert gas containing 96 mol% of L-lactide and 4 mol% of D-lactide, mixed at 165 ° C. for 1 hour, and added with 0.02 parts by weight of tin octoate as an esterification catalyst to give 8 parts. A time reaction was performed. After this,
As a deactivator, 0.04 parts by weight of an acidic phosphoric acid ester was added and kneaded. Further, devolatilization was carried out under heating and reduced pressure by a twin screw extruder. The conditions of devolatilization are as follows: devolatilization time is 120 seconds, temperature is 200
° C, and the degree of reduced pressure is 5 Torr. The obtained lactic acid-based polymer was a colorless and transparent resin, and the weight average molecular weight was 272,000 from the result of GPC measurement. This polymer is called P5.

Aliphatic polyester (weight average molecular weight:
35,000 (GPC, polystyrene equivalent), sebacic acid 5
0 mol%, 1,6 hexanediol 20 mol%, ethylene glycol 20 mol%, 1,3 butanediol 10
%) 3 parts by weight and 97 parts by weight of lactide (L-lactide 99 mol%, D-lactide 1 mol%)
The atmosphere was replaced with an inert gas, mixed at 170 ° C. for 1 hour, added with 0.02 parts by weight of tin octoate as an esterification catalyst, and added with 1% of pyromellitic acid as a high molecular weight agent, and reacted for 8 hours. went.

Thereafter, 0.04 parts by weight of an acidic phosphoric acid ester as a deactivator was added and kneaded. Further, devolatilization was carried out under heating and reduced pressure by a twin screw extruder. The conditions for devolatilization are as follows:
For 20 seconds, the temperature is 200 ° C., and the degree of reduced pressure is 5 Torr.
The obtained lactic acid-based polymer was a colorless and transparent resin, and the weight average molecular weight was 350,000 based on the result of GPC measurement. This polymer is called P6.

(Examples 1 to 12) Lactic acid polymers shown in Tables 1 to 3 and carbon black (Toka Black # 4500 manufactured by Tokai Carbon Co., Ltd .: specific surface area 5)
(8 m ² / g, particle diameter 40 nm) so that the co-extrusion device (manufactured by Tanabe Plastics Co., Ltd.) extrudes the lactic acid-based polymer so that the content of the conductivity-imparting agent becomes the value shown in the table. An evaluation sheet having a thickness of 0.3 mm made of a lactic acid-based polymer laminate of two or two layers or two or three layers was prepared. Tables 1 to 3 show the layer constitution ratio and various evaluation results of the lactic acid-based polymer laminate sheet. The appearance of the sheet obtained in each example was smooth, and all were good.

(Method of Evaluating Thermoformability) (1) Vacuum Formability The obtained sheet having a thickness of 0.3 mm was placed with an opening of 100 × 80 mm and a depth of 30 mm so that the conductivity-imparting layer side was the inner surface of the molded product. Using the mold described above, vacuum molding was performed under the molding conditions of a heater temperature of 450 ° C., a heating time of 9 seconds, and a mold temperature of 30 ° C., and the appearance of the molded product was evaluated. It was confirmed whether or not there was a defect phenomenon such as a mold reproduction defect or a thin portion such as a corner portion or a crack. The evaluation criteria are as follows. ：: good appearance, × poor appearance

(2) Press Formability The obtained sheet having a thickness of 0.3 mm was heated using a female mold having an opening of 68 × 68 mm and a depth of 11 mm so that the conductivity-imparting layer side was the inner surface of the molded product. Press molding was performed at a temperature of 450 ° C., a heating time of 7 seconds, and a mold temperature of 30 ° C., and the appearance of the molded product was evaluated. It was confirmed whether or not there was a defect phenomenon such as a mold reproduction defect or a thin portion such as a corner portion or a crack. The evaluation criteria are as follows. ：: good appearance, × poor appearance

(Surface Resistance Value of Molded Product Obtained by Thermoforming)
Using a commercially available tester (Digital Ultra High Resistance Meter R8340 and Tweezers Probe R12604, manufactured by Advantest), the electrodes were brought into contact with the bottom surface of the inner side of the molded product on the side of the conductivity imparting layer at 10 mm intervals, and the resistance value was measured. . The evaluation criteria are as follows. ：: less than 10 ⁸ Ω ○: 10 ⁸ Ω or more and less than 10 ¹⁰ Ω ×: 10 ¹⁰ Ω or more

(Method of evaluating rigidity) Obtained thickness 0.3 m
The tensile secant modulus (1% secant modulus) at 1% strain was measured using a No. 1 type test piece at a tensile speed of 10 mm / min according to JISK-7127 using a sheet of m. The evaluation criteria are as follows. ◎: 1.6 GPa or more ○: 1.2 GPa or more, less than 1.6 GPa ×: less than 1.2 GPa

(Evaluation method of impact resistance) Using a Dupont impact strength measurement method, a weight having a constant weight was dropped at different heights, and depending on the presence or absence of breakage, a sheet having a thickness of 0.3 mm was obtained. The 50% breaking energy was determined. The striking portion with the sheet is made of steel and has a smooth hemisphere with a radius of 6.3 mm. In addition, the measurement was performed by setting a sheet so that the conductivity-imparting layer side was the hitting side. ◎: 0.5 J or more ○: 0.1 J or more, less than 0.5 J ×: less than 0.1 J

(Method of evaluating biodegradability) 5 kg of garbage was put into an outdoor compost (capacity: 100 liters), and cut out from a sheet having a thickness of 0.3 mm obtained thereon.
A test piece of cm square was placed. Further, the state of the test piece was visually evaluated one month after placing garbage having a thickness of about 5 cm. This test was performed in summer. The evaluation criteria are as follows. When the physical properties were remarkably deteriorated and the shape was difficult to maintain, it was evaluated as "O".

[0093]

[Table 1]

[0094]

[Table 2]

[0095]

[Table 3]

(Comparative Examples 1 to 4) Lactic acid-based polymers shown in Table 4 and carbon black (Toka Black # 4500 manufactured by Tokai Carbon Co., Ltd .; specific surface area: 58 m ² ) as a conductivity-imparting agent
/ G, particle diameter 40 nm) when extruded with a co-extrusion apparatus (manufactured by Tanabe Plastics Co., Ltd.) so that the content of the conductivity-imparting agent of each lactic acid-based polymer becomes the value shown in the table. An evaluation sheet having a thickness of 0.3 mm made of a two-layer lactic acid-based polymer laminate was prepared. Table 4 shows the layer composition ratio of the lactic acid-based polymer laminate sheet and various evaluation results.
Each evaluation method was performed in the same manner as in Examples 1 to 12.

[0097]

[Table 4]

Reference Examples 1 to 3 Carbon black (Toka Black # 4500 manufactured by Tokai Carbon Co., Ltd .: specific surface area: 58) was obtained by extrusion molding using the lactic acid-based polymer shown in Table 5.
A lactic acid-based polymer sheet was prepared using an extruder (manufactured by Tanabe Plastics Co., Ltd.) such that the content of m ² / g and the particle diameter was 40 nm as shown in the table. The thickness of the sheet is 0.3mm
And was used as an evaluation sheet. Table 5 shows the evaluation results. Each evaluation method was performed in the same manner as in Examples 1 to 12.

[0099]

[Table 5]

[0100]

According to the present invention, practical conductivity, biodegradability,
It is possible to provide a conductive lactic acid-based polymer laminate having good appearance, rigidity, impact resistance, and heat workability, and a sheet or container comprising the laminate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B29L 22:00 F term (reference) 4F100 AA37 AK41A AK41B AK54A AK54B BA02 BA26 CA21A CA21B DA01 EH17 GB16 GB41 JA07A JA07B JC00 JG01A JG01B JG04B JK01 JK10 JL01 YY00 YY00A YY00B 4F207 AA24 AA32 AB13 AE03 AE09 AE10 AG03 AG07 KA01 KB26 KE06 KF01 KF02 KJ09 KK82 4F208 AA24 AA32 AB13 MG01 MG01 MG01 MG01 MG01 MG01 MG01 MG01 MG03 FD116

Claims (9)

[Claims] 1. Lactic acid containing 17 to 40% by weight of a conductivity-imparting agent on at least one surface of a base layer (I) comprising a lactic acid-based polymer (A) containing 12% by weight or less of a conductivity-imparting agent. A conductive lactic acid-based polymer laminate having a surface resistance value of 10 ¹⁰ Ω or less on the side of the conductivity-imparting layer (II), on which the conductivity-imparting layer (II) made of the polymer (B) is formed. 2. The conductive lactic acid-based polymer laminate according to claim 1, wherein the lactic acid-based polymer (A) and / or the lactic acid-based polymer (B) is polylactic acid. 3. A lactic acid-based polymer (A) and / or a lactic acid-based polymer (B) is a polyester structural unit obtained by dehydration-condensation of a dicarboxylic acid and a diol and / or a polyether structure obtained by dehydration-condensation of a dicarboxylic acid and a polyether polyol. The conductive lactic acid-based polymer laminate according to claim 1, which is a lactic acid-based polymer containing 3 to 40% by weight of a unit. 4. A thickness D (II) of the conductivity-imparting layer (II),
The ratio of the thickness D (I) of the base material layer (I) is D (II) / D (I) =
The conductive lactic acid-based polymer laminate according to any one of claims 1 to 3, which has a value of 0.03 to 0.8. 5. The lactic acid-based polymer (A) or (B) is a lactic acid-based polymer whose molecular weight has been increased by adding a high-molecular-weight agent such as a polycarboxylic acid, an acid anhydride, or a polyvalent isocyanate. Item 5. The conductive lactic acid-based polymer laminate according to any one of Items 1 to 4. 6. The lactic acid-based polymer (A) or (B) is a lactic acid-based polymer in which the residual monomer is reduced by deactivating the polymerization catalyst with a deactivator for the polymerization catalyst, or by devolatilizing or reprecipitating. The conductive lactic acid-based polymer laminate according to any one of claims 1 to 4. 7. The 1% secant modulus is 1.2 GP.
The conductive lactic acid-based polymer laminate according to any one of claims 1 to 4, which is at least a. 8. A sheet obtained by extruding the conductive lactic acid-based polymer laminate according to claim 1. 9. A container obtained by thermoforming the conductive lactic acid-based polymer laminate according to any one of claims 1 to 7.