JP3496196B2 - Method for producing biodegradable resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable resin composition and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, various resin molded products have been used as agricultural / horticultural materials (for example, polyvinyl chloride film) and fishery materials (for example, polyethylene fiber fishing nets). , These materials will eventually be discarded. Therefore, there is a demand for a resin that does not become a pollution source even when it is discarded and is hydrolyzed with time or biodegraded by microorganisms in the soil. The present inventors have previously utilized such materials for agriculture and horticulture, materials for fisheries, etc., and even if they are discarded after use, they are hydrolyzed and / or decomposed into carbon dioxide and water by microorganisms in the soil. Invented a method for easily producing a polyhydroxycarboxylic acid resin and filed an application (Japanese Patent Application No. 8-561).
No. 81), the present invention increases the melting point of the hydrolyzable and / or biodegradable polyhydroxycarboxylic acid resin,
Moreover, by increasing the resin strength and melt viscosity, it is an object (problem) to provide a resin composition that facilitates foaming by a low boiling point solvent method, a gas injection method, a chemical foaming agent method, etc. To do.

[0003]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that carbon black as a filler for a polyhydroxycarboxylic acid resin which is a hydrolyzable and / or biodegradable resin. It was discovered that the melting point of the resin can be increased and the resin strength and the melt viscosity can be increased by adding the above, and the present invention has been completed.

The preparation process of a biodegradable resin composition of Sunawa Chi invention, mixtures of hydroxycarboxylic acids or two or more hydroxycarboxylic acids, mixtures of hydroxycarboxylic acids and saccharides, or hydroxycarboxylic acids and metal hydrosulfide and a polymerization catalyst into a mixture of oxides and / or inorganic acids
Then 1,3-substituted-1,1,3,3-tetraorganodi
Stannoxane is added, azeotropic dehydration polymerization is performed in an organic solvent, or a polyhydroxycarboxylic acid resin is synthesized by heating and stirring under reduced pressure, and carbon black is added as a filler to the polyhydroxycarboxylic acid resin. It is a thing.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyhydroxycarboxylic acid resin used in the present invention is an aliphatic carboxylic acid having a hydroxyl group, and in the case of having an asymmetric carbon, one or two of D-form, L-form and racemic form. It is obtained by polymerizing the above hydroxycarboxylic acid. Further, instead of the hydroxycarboxylic acid polymer, a copolymer may be synthesized from hydroxycarboxylic acid and starch, hydroxycarboxylic acid and metal hydroxide and / or inorganic acid and used.

The carbon black as a filler used in the present invention may be either activated carbon or inert carbon, and examples of the inert carbon include hard carbon and soft carbon.

The amount of carbon black added is preferably 1 to 300 parts by weight based on 100 parts by weight of the polyhydroxycarboxylic acid resin. If it is less than 1 part by weight, the thickening effect cannot be obtained,
If it exceeds 300 parts by weight, the viscosity is remarkably increased and the workability is deteriorated. The resin and carbon black may be kneaded using any of an extruder, a kneader, a roll and various mixers.

As the catalyst for polymerizing the hydroxycarboxylic acid, any catalyst used in general ester polymerization may be used, but 1,3-substituted-1,1, which has high catalytic activity and hydrolysis resistance, 3,3-Tetraorganodistannoxane is preferred. The organo group bonded to the tin atom of 1,3-substituted-1,1,3,3-tetraorganodistannoxane is a methyl group, an ethyl group, a butyl group, an octyl group, an allyl group, a benzyl group, a phenyl group, It may be any such as a naphthyl group, and the substituents at the 1,3 position are halogens,
It may be any of thiocyano group, hydroxyl group, alkoxy group and carboxyl group.

Hydroxycarboxylic acids which are raw materials for synthesizing polyhydroxycarboxylic acid resins include lactic acid, glycolic acid, tartaric acid, citric acid, malic acid, oxyvaleric acid, and 2
-Hydroxystearic acid, salicylic acid, o-oxycinnamic acid, or a mixture thereof can be mentioned, with lactic acid being particularly preferred. Further, a hydroxycarboxylic acid dimer or a hydroxycarboxylic acid oligomer may be used instead of the hydroxycarboxylic acid.

The saccharides to be copolymerized with hydroxycarboxylic acid are preferably natural ones, such as D-glucose,
Monosaccharides such as D-fructose, D-mannose and D-galactose, oligosaccharides such as maltose and sugar (sucrose), starch, especially polysaccharides such as corn starch, sweet potato starch, wheat starch, or the like. Can be mentioned.

As the metal hydroxide to be copolymerized with hydroxycarboxylic acid, aluminum hydroxide, calcium hydroxide, zinc hydroxide, barium hydroxide, magnesium hydroxide, or a mixture thereof is used, and as the inorganic acid, , Boric acid, silicic acid, phosphoric acid, or a mixture thereof.

The polymerization catalyst used in the polymerization or copolymerization of hydroxycarboxylic acid is 1,3-substituted-1,
Mention may be made of 1,3,3-tetraorganodistanoxane. Here, the organo group bonded to the tin atom may be any of a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, an allyl group, a benzyl group, and a phenyl group, but considering the solubility and cost, the butyl group is considered. Is preferred. Further, the substituents at the 1 and 3 positions may be any of halogen, thiocyano group, hydroxyl group, alkoxy group and carboxyl group.

As the organic solvent used in the reaction, any organic solvent may be used as long as it has a boiling point higher than that of water and is not compatibilized with water. D-limonene or decalin which has less adverse effect on

[0014]

The polyhydroxycarboxylic acid resin to which carbon black is added as a filler according to the present invention has a higher melt viscosity than the polyhydroxycarboxylic acid resin to which carbon black is not added. And foaming by chemical foaming method are easy. Further, even if the composition according to the present invention is discarded, the polyhydroxycarboxylic acid resin is hydrolyzed and decomposed into carbon dioxide and water by microorganisms in the soil, while carbon black is chemically stable and is environmentally friendly. Has little effect.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

(Example 1) 90% L-lactic acid 3 kg (30 mol) and 1,3 in a 5 liter planetary mixer
-Dichloro-1,1,3,3-tetrabutyl distannoxane (1.5 g, 3 mmol) was added, and the mixture was vacuum-stirred at 170 ° C for 24 hours to synthesize polylactic acid. Soft carbon was added thereto in an amount of 40 parts by weight with respect to 100 parts by weight of polylactic acid, and the mixture was further vacuum stirred at 170 ° C. for 4 hours. In addition, as soft carbon, SRF grade, FEF
Grade and HAF grade carbon black were used. The melting point of polylactic acid increased from 88 ° C. to 108 ° C. as compared with before the addition of carbon black. Further, when the melt viscosity of the polylactic acid before and after the addition of carbon black was measured, it increased from 19850 poise to 99280 poise. A constant load extrusion type thin tube rheometer CFT-500C (manufactured by Shimadzu Corporation) was used for measuring the melting point and the melt viscosity.

(Example 2) 90% L-lactic acid 3 kg (30 mol) and 1,3 in a 5 liter planetary mixer.
-Dichloro-1,1,3,3-tetrabutyl distannoxane (1.5 g, 3 mmol) was added, and the mixture was vacuum-stirred at 170 ° C for 24 hours. Activated carbon powder was added thereto in an amount of 40 parts by weight with respect to 100 parts by weight of polylactic acid,
Furthermore, it mixed at 170 degreeC for 4 hours. The melting point of polylactic acid increased from 88 ° C. to 114 ° C. as compared with before the addition of activated carbon powder. Further, when the melt viscosity of the polylactic acid before and after the addition of the activated carbon powder was measured, it increased from 19850 poise to 45130 poise.

[0018]

As described above, according to the present invention, the polyhydroxycarboxylic acid resin composition containing carbon black as a filler has a melting point higher than that of the polyhydroxycarboxylic acid resin composition containing no carbon black. It is easy to foam by low boiling point solvent method, gas injection method, chemical blowing agent method, etc. due to its high resin strength and melt viscosity, and polyhydroxycarboxylic acid resin hydrolyzes even when it is discarded. While it does not become a pollution source by being decomposed into carbon dioxide and water by microorganisms in the soil, etc., carbon black is chemically stable and has little impact on the environment. There is a great possibility that the molded product can be used for agricultural and horticultural materials and fishery materials.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 63/00-63/91 C08L 67/04 WPI / L (QUESTEL)

Claims (3)

(57) [Claims] 1. A hydroxycarboxylic acid or two or more hydroxycarboxylic acids.
A mixture of droxycarboxylic acids, hydroxycarboxylic acids
Mixture with sugar or hydroxycarboxylic acid and metallic water
With a polymerization catalyst in a mixture with oxides and / or inorganic acids
Then 1,3-substituted-1,1,3,3-tetraorganodi
Add stannoxane and perform azeotropic dehydration polymerization in an organic solvent.
Or polyhydric acid by heating and stirring under reduced pressure
Roxycarboxylic acid resin was synthesized and used as a filler.
Biodegradability characterized by adding carbon black
A method for producing a resin composition. 2. A hydroxycarboxylic acid or two or more hydroxycarboxylic acids.
A mixture of droxycarboxylic acids, hydroxycarboxylic acids
Mixture with sugar or hydroxycarboxylic acid and metallic water
Polymerization catalyst in a mixture with oxides and / or inorganic acids
Add and perform azeotropic dehydration polymerization in organic solvent or reduce
Polyhydroxycarboxylic acid by heating and stirring under pressure
Acid resin was synthesized and carbon black was used as a filler.
Biodegradable foaming characterized by adding foam to foam
For producing a synthetic resin composition. 3. The polymerization catalyst is 1,3-substituted-1,1,3,3
-Tetraorganodistannoxane
A method for producing the biodegradable foamed resin composition according to claim 2.
Law.