JPH1160917A - Biodegradable resin composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in mechanical performance, moldability, and heat resistance, and usable as a medicine, a cosmetic, a food, a wrapping member, a machine part, a fiber, and clothes as the like by including a specific plasticizer and an aliphatic polyester. SOLUTION: The objective composition comprises (A) a plasticizer containing one kind or more ricinoleic acid derivative (e.g. acetylricinoleic acid), which is the acetylated, methylated or ethylated ricinoleic acid or the like, (B) an aliphatic polyester preferably having >=10,000 weight average molecular weight, and (C) optionally an inorganic filler, a pigment, an antioxidant, a crystalline nucleating agent or the like. The component B is essentially a polyhydroxyalkanoate produced by microorganisms, and can includes the chemically synthesized one from a glycols and an aliphatic dicarboxylic acid, or a hydroxycarboxylic acid. The ratio of the components A to B is preferably 5-40 pts.wt., preferably 10-30 pts.wt. component A to 100 pts.wt. component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent moldability and mechanical performance, and is used as a packaging member, a machine part, a fiber, a monofilament, a garment, etc. of medicines, cosmetics, food and industrial materials and machinery. And a resin composition having excellent biodegradability.

[0002]

2. Description of the Related Art Conventionally, many plastics are used in various industrial fields as molding materials for packaging materials, clothing, fibers, monofilaments, and industrial machine parts. At the same time, from the standpoint of environmental protection, the recycling of plastic is called out, and the use of biodegradable resins that degrade by the action of microorganisms or hydrolysis is strongly demanded in applications where recycling is not possible. Have been.

[0003] Aliphatic polyesters are produced by chemical synthesis or microbial fermentation. Aliphatic polyesters generally exhibit hydrolytic properties and biodegradability due to the action of microorganisms widely distributed in nature, and are thermoplastic, so they are actively used for various applications by existing molding methods. Is being considered. However, many aliphatic polyesters, especially polyhydroxyalkanoic acids produced by microorganisms, have melting points and decomposition onset temperatures close to each other, and furthermore have insufficient thermal stability in a molten state, so that molding is difficult. Furthermore, polyhydroxyalkanoic acids produced by microorganisms mainly contain 3-hydroxybutyric acid as a component,
As the molar ratio of -hydroxybutyric acid increases, the resulting molded article becomes hard and brittle, and the molar ratio of 3-hydroxybutyric acid becomes 10%.
In the case of 0%, the elongation of the molded product is extremely small at about 1%. Therefore, modification by adding a plasticizer such as triacetin has been conventionally attempted. However, for example, when 10% by weight of triacetin is added to poly-3-hydroxybutyric acid, the melting point is reduced by about 10 ° C., and the temperature difference from the decomposition start temperature is increased. The elongation rate of the molded article obtained is about 2%, and the effect is insufficient. In addition, since triacetin has a relatively high amount of evaporation at a high temperature, a gas generated during molding often has a bad influence on a molded product. Recently, the use of tributyl acetyl citrate, which has a small amount of evaporation at a high temperature, has been proposed. However, the elongation of a molded product is not different from that when triacetin is used, and the effect is insufficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a biodegradable resin which solves the above-mentioned problems in the prior art and is excellent in mechanical performance, moldability and heat resistance.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the ricinoleic acid derivative plasticizes the aliphatic polyester, and furthermore, it has been found that this has the effect of expanding the moldable temperature range due to the lowering of the melting point and greatly increasing the elongation of the molded article, and completed the present invention. .

The gist of the present invention is that (1) a biodegradable resin composition comprising a plasticizer containing at least one kind of ricinoleic acid derivative and an aliphatic polyester, and (2) the ricinoleic acid derivative is methyl acetyl ricinoleate. (1) the biodegradable resin composition according to (1), (3) the biodegradable resin composition according to (1), wherein the aliphatic polyester is a polyhydroxyalkanoic acid produced by a microorganism; Contains a 3-hydroxybutyric acid unit (1)
The weight-average molecular weight of the biodegradable resin composition described in (1), wherein the (5) aliphatic polyester is poly-3-hydroxybutyric acid, and (6) the aliphatic polyester, The biodegradable resin composition according to (1), which is 10,000 or more, and further obtained by melt-kneading (7) a plasticizer and an aliphatic polyester.
(6) The method for producing a biodegradable resin composition according to any one of (6) and (8) a temperature at 140 ° C to 220 ° C during melt-kneading.
(7) The method for producing a biodegradable resin composition according to (7).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The ricinoleic acid derivative shown in the present invention indicates ricinoleic acid which has been acetylated, methylated, ethylated and the like. Specifically, methyl acetyl ricinoleate can be mentioned. Methyl acetyl ricinoleate has a boiling point of 218 ° C. (normal pressure) of triacetin, which has been conventionally used as a plasticizer for aliphatic polyester, whereas methyl acetyl ricinoleate has a boiling point of 173 ° C. (1 ° C.).
mmHg under reduced pressure), and there is little possibility that inconvenience such as the expected performance not being obtained due to evaporation may occur.
The small amount of steam generated from the vent port and the die is also excellent in working environment. Methyl acetyl ricinoleate has been used for the plasticization of chewing gum base materials and has a low risk of causing safety problems.

The aliphatic polyester represented by the present invention is mainly a polyhydroxyalkanoate produced by a microorganism, but also includes those chemically synthesized from glycols and aliphatic dicarboxylic acids or from hydroxycarboxylic acids. Polyhydroxyalkanoates are, for example, those of the genus Alcaligenes, Azoto
bacter), Methylobacterium
Genus, Nocardia, Pseudomonas (Pseu)
domonas) by a known fermentation method using a bacterium such as the genus domonas. Regarding the method of separating and purifying the polyhydroxyalkanoic acid obtained by the fermentation method, for example,
U.S. Pat. Nos. 3,036,959 and 4,015,533
No. 3,275,610 and European Patent No. 15123, pyridine, methylene chloride, 1,2
-A purification method using a solvent such as propylene carbonate, chloroform, 1,2-dichloroethane and the like is described, and JP-A-7-177894 discloses that bacterial cells are crushed with a high-pressure homogenizer, and then polyhydroxyalkanoic acid is added. A method is described in which the separated and separated polyhydroxyalkanoic acid is treated with an oxygen bleach.

The aliphatic polyester used in the present invention preferably has a weight average molecular weight of 10,000 or more.
Because, among the aliphatic polyesters, especially polyhydroxyalkanoic acid, some of them have poor thermal stability, the melt viscosity is lowered during melt molding, and a satisfactory molded product cannot be obtained, or the mechanical property of the molded product is poor. This is because problems such as insufficient performance occur.

The ratio of the aliphatic polyester to the plasticizer containing at least one ricinoleic acid derivative in the biodegradable resin composition of the present invention varies depending on the type of the aliphatic polyester used.
The plasticizer is 5 to 40 parts by weight based on 0 parts by weight, and preferably the plasticizer 10 to 10 parts by weight based on 100 parts by weight of the aliphatic polyester.
30 parts by weight.

[0011] The biodegradable composition of the present invention comprises
Depending on the molding method, conventional auxiliary additives such as inorganic fillers, pigments, antioxidants, and crystal nucleating agents can be added in addition to the plasticizer. In the biodegradable resin composition of the present invention, it is desirable that a plasticizer and an aliphatic polyester are melt-kneaded. This is because the melt-kneading uniformly disperses the plasticizer in the aliphatic polyester, and can give the obtained molded product the expected mechanical performance. At that time, the temperature at the time of melt kneading must be lower than the decomposition start temperature of the aliphatic polyester.

The biodegradable resin composition of the present invention is prepared by injection molding, injection blow molding, injection stretch blow molding, extrusion, extrusion blow molding, extrusion stretch blow molding, stretching, rolling, thermoforming, spinning, and spinning involving stretching. Converted into sheets, films, containers, bottles, tubes, monofilaments, multifilaments, fibers, non-woven fabrics, woven fabrics, machine parts, sports equipment parts by molding methods generally applicable to thermoforming resins such as spinning be able to. Particularly specific uses of these molded products include materials that are impossible or difficult to recover or reuse after use, such as medical equipment and fixtures, containers for foods, drugs, spices, garbage bags, fishing lines, fishing nets, etc. Yarns, nets, medical and industrial fabrics, and other industrial and agricultural materials.

[0013]

Industrial Applicability The composition of the present invention is excellent in moldability, mechanical properties, heat resistance and biodegradability, and is suitable for films, sheets, fibers, containers, bottles, tubes, injection molded articles and various molded articles. Give things.

[0014]

(Measurement of weight average molecular weight)

Method: Gel permeation chromatography (GPC) Solvent: chloroform Flow rate: 1 ml / min [Measurement of melting point] Apparatus: Differential scanning calorimeter (DSC) Method: JIS K 7121 [Tensile performance] Apparatus: Tensile tester Test piece Shape: strip-shaped 100 mm long, 10 mm wide, 50 mm between chucks Peeling speed: 50 mm / min Measurement environment: temperature 23 ° C., relative humidity 50%

Examples 1 to 3 A bacterium, Protomonas extorquens, deposited at the Institute of Biotechnology and Industrial Technology, National Institute of Advanced Industrial Science and Technology.
xtorquens) K (Accession number: FERM BP-354)
Using 8), continuous culture was performed aerobically using methanol as a carbon source. The culture conditions were a culture temperature of 32 ° C. and a culture pH of 6.
5. Continuous cultivation was performed so that the average residence time was 40 hours, and the nitrogen supply rate was the rate-determining rate of bacterial cell growth. According to recent literature, this bacterium is methylobacterium (Methylobac
terium) (IJBousfield and PNGr)
een; Int.J.Syst.Bacteriol., 35,209 (1985), T. Urakami
etal .; Int. J. Syst. Bcteriol., 43, 504-513 (1993)). The cells obtained by continuous culturing were subjected to the method described in JP-A-7-17789.
In accordance with the method for separating and purifying poly-3-hydroxybutyric acid described in Japanese Patent Publication No. 4 (1999), after crushing with a high-pressure homogenizer, centrifuging, the separated poly-3-hydroxybutyric acid is first treated with a protease, and then treated with hydrogen peroxide to obtain high purity. Poly-3-
Hydroxybutyric acid was obtained. The weight average molecular weight of this purified poly-3-hydroxybutyric acid was 800,000.
Methyl acetyl ricinoleate was added to 100 parts of this poly-3-hydroxybutyric acid so as to be 10 to 30 parts by weight, mixed, and then pelletized using a screw type extruder. The screw temperature at that time is 170-1
Performed at 80 ° C. The weight average molecular weight at the time of pelletization was 500,000. The poly thus obtained
The melting point of the 3-hydroxybutyric acid pellet was measured.

The plasticizer-added poly-3-hydroxybutyric acid pellets obtained by the above method are subjected to a single screw extruder [Laboplast Mill, manufactured by Toyo Seiki Co., Ltd., screw diameter: 20 m].
m] and a cylinder temperature of 170 to 180 ° C. and a T-die / cooling roll method (cooling roll temperature: 60
° C), and a film having a thickness of about 200 µm was obtained. A strip-shaped test piece having a length of 100 mm and a width of 10 mm was cut out from the obtained film, and the tensile performance was examined. Table 1 shows the results.

Comparative Example 1 Poly-3 purified from cells by the same method as in Examples 1 to 3.
-Hydroxybutyric acid was pelletized using a screw type extruder. The screw temperature at that time is 180-19
Performed at 0 ° C. The weight average molecular weight at the time of pelletization was 450,000. Poly-3 thus obtained
-The melting point of the hydroxybutyric acid pellets was measured. Poly-3
Using a single screw extruder [Labo Plast Mill, manufactured by Toyo Seiki Co., Ltd., screw diameter: 20 mm] with a cylinder temperature of 180 to 190 ° C and a T-die / cooling roll method, the hydroxybutyric acid pellets (cooling roll temperature: 60 ° C.) and a film having a thickness of about 200 μm was obtained. A strip-shaped test piece having a length of 100 mm and a width of 10 mm was cut out from the obtained film, and the tensile performance was examined. Table 1 shows the results.

Comparative Examples 2 to 4 Poly-3 purified from cells by the same method as in Examples 1 to 3
Triacetin was added to 100 parts of hydroxybutyric acid in an amount of 10 to 30 parts, mixed, and then pelletized using a screw type extruder. The screw temperature at that time was 170-180 ° C. The weight average molecular weight at the time of pelletization was 500,000. The melting point of the thus obtained poly-3-hydroxybutyric acid pellets was measured. The plasticizer-added poly-3-hydroxybutyric acid pellets obtained by the above-mentioned method are mixed with a single screw extruder [Labo Plastomill, manufactured by Toyo Seiki Co., Ltd., screw diameter: 20 m]
m] and using a T-die / cooling roll method with a cylinder temperature of 170 to 180 ° C. (cooling roll temperature: 60
° C), and a film having a thickness of about 200 µm was obtained. A strip-shaped test piece having a length of 100 mm and a width of 10 mm was cut out from the obtained film, and the tensile performance was examined. Table 1 shows the results.

Comparative Examples 5 to 7 Poly-3 purified from cells by the same method as in Examples 1 to 3
-To 100 parts of hydroxybutyric acid, 10 to 30 parts of tributyl acetylcitrate was added and mixed, and then pelletized using a screw type extruder.
The screw temperature at that time was 170-180 ° C.
The weight average molecular weight at the time of pelletization is 500,00
It was 0. The melting point of the thus obtained poly-3-hydroxybutyric acid pellets was measured. The plasticizer-added poly-3-hydroxybutyric acid pellets obtained by the above method were subjected to single-screw extruder [Labo Plastmill, manufactured by Toyo Seiki Co., Ltd., screw diameter: 20 mm], and the cylinder temperature was adjusted to 170.
A temperature of about 180 ° C. and a T-die cooling roll method (cooling roll temperature: 60 ° C.) yielded a film having a thickness of about 200 μm. Length 100mm, width 10mm from the obtained film
Was cut out and the tensile performance was examined. Table 1 shows the results.

[0020]

[Table 1]

Claims (8)

[Claims] 1. A biodegradable resin composition comprising a plasticizer containing at least one ricinoleic acid derivative and an aliphatic polyester. 2. The biodegradable resin composition according to claim 1, wherein the ricinoleic acid derivative is methyl acetyl ricinoleate. 3. The biodegradable resin composition according to claim 1, wherein the aliphatic polyester is a polyhydroxyalkanoic acid produced by a microorganism. 4. The biodegradable resin composition according to claim 1, wherein the aliphatic polyester contains a 3-hydroxybutyric acid unit. 5. The biodegradable resin composition according to claim 1, wherein the aliphatic polyester is poly-3-hydroxybutyric acid. 6. The biodegradable resin composition according to claim 1, wherein the aliphatic polyester has a weight average molecular weight of 10,000 or more. 7. The method for producing a biodegradable resin composition according to claim 1, which is obtained by melt-kneading a plasticizer and an aliphatic polyester. 8. The temperature at the time of melt-kneading is from 140 ° C. to 230 ° C.
8. The method for producing a biodegradable resin composition according to claim 7, wherein the method is performed.