JPH11323116A - Biodegradable molding material, biodegradable molded article, and molding method for the biodegradable molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable molding material which has a good moldability and gives a molded article excellent in biodegradability and mechanical properties by compounding an aliph. polyester contg. at least a specified amt. of a resin contg. 3-hydroxybutyric acid units with glass fibers. SOLUTION: This molding material comprises 40-95 wt.% aliph. polyester and 5-60 wt.% glass fibers. The aliph. polyester contains at least 50 wt.% resin contg. 3-hydroxybutyric acid units. Pref., the resin contg. 3-hydroxybutyric acid has a wt. average mol.wt. of 100,000 or higher, and the rest of the aliph. polyester resin has a wt. average mol.wt. of 100,000-1,000,000. This aliph. polyester is a copolymer of a polyhydroxyalkanoate contg. 3-hydroxybutyric acid units, polylactic acid, a glycol, an aliph. carboxylic acid, etc. Glass fibers are added e.g. by coating with the aliph. polyester resin by melt extrusion followed by pelletizing or by mixing in an injection molding machine followed by molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable molding material containing glass fibers and a molded product. More specifically, a biodegradable resin molding material blended with glass fibers having excellent moldability such as shortening the molding cycle time, high rigidity, excellent physical performance such as high shape stability, and excellent biodegradability, The present invention relates to a biodegradable molded product obtained from the biodegradable molding material and a method for forming and processing the biodegradable molding material.

[0002]

2. Description of the Related Art Conventionally, many plastics have been used as molding materials for industrial materials, machine parts, automobile parts and the like. At the same time, from the standpoint of environmental protection, the recycling of plastics is called for, and the use of biodegradable resins, which degrade by the action of microorganisms or hydrolysis, is strongly used in applications where recycling is not possible. It has been requested.

[0003] It is widely known that aliphatic polyesters have biodegradability, and can be produced by a fermentation method using a microorganism, a chemical synthesis method, or the like. Aliphatic polyesters obtained by fermentation are generally polyhydroxyalkanoates and usually contain 3-hydroxybutyric acid units, but their molecular compositions and molar ratios have been widely studied to derive performance suitable for the application. I have. In the chemical synthesis method, polycaprolactone, polybutylene succinate,
Polyethylene succinate, polyester carbonate, polylactic acid, and the like are well known, and application development according to their characteristics is widely studied. For applications where high rigidity is required-for example, joining members, rigid daily necessities, other rigid medical, industrial and agricultural materials-
-Use of aliphatic polyesters and polylactic acids containing many hydroxybutyric acid units is expected. However, some aliphatic polyesters and polylactic acids containing a large amount of 3-hydroxybutyric acid units, such as poly-3-hydroxybutyric acid, have insufficient rigidity depending on the intended use, and in addition, contain a large amount of 3-hydroxybutyric acid units. Aliphatic polyesters have low tensile strength and bending strength, and polylactic acid takes a long time to solidify from a molten state, so a long molding cycle time is required.
The shape stability described above is inferior. For these reasons, the use of biodegradable resins in fields requiring high rigidity is currently limited.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and provides a biodegradable molding material and a molded article having excellent moldability, mechanical performance and biodegradability. The subject.

[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, by blending the glass fiber with the aliphatic polyester, high rigidity is achieved, the moldability, the effects of improving shape stability, etc. are obtained, and it is found that the performance can be sufficiently used as a molding material. Completed. That is, the present invention relates to (1) aliphatic polyesters 40 to 9
5% by weight and 5-60% by weight of glass fiber,
And a biodegradable molding material in which the aliphatic polyester is a resin containing 50% by weight or more of a resin containing a 3-hydroxybutyric acid unit, and (2) a resin containing a 3-hydroxybutyric acid unit has a weight average molecular weight of 100,000 or more. The biodegradable molding material according to (1), wherein the aliphatic polyester other than the resin containing 3-hydroxybutyric acid unit has a weight average molecular weight of 10,000 to 1,000,000, The biodegradable molding material according to (1) or (2), wherein the resin containing a butyric acid unit is poly-3-hydroxybutyric acid.
(4) a biodegradable molded product obtained from the biodegradable molding material according to (1), and (5) an aliphatic polyester 40 to
A biodegradable molding material comprising 95% by weight and glass fiber of 5 to 60% by weight, and wherein the aliphatic polyester is a resin containing 50% by weight or more of a resin containing a 3-hydroxybutyric acid unit. The present invention relates to a method for forming a biodegradable molding material at 90 ° C.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The aliphatic polyesters represented by the present invention include polyhydroxyalkanoates containing 3-hydroxybutyric acid units produced by microorganisms, polylactic acids, polymers from glycols and aliphatic carboxylic acids, and the like. Is a copolymer of Examples of the resin containing a 3-hydroxybutyric acid unit include poly-3-hydroxybutyric acid, a copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, and a copolymer of 3-hydroxybutyric acid and 4-hydroxyvaleric acid. is there. Poly-3-hydroxybutyric acid is, for example, alkaligenes (Alca)
Ligenes), Azotobacter, Methylobacterium, Nocardia, Pseudomonas, and other known fermentation methods. Regarding a method for separating and purifying poly-3-hydroxybutyric acid obtained by a fermentation method from bacterial cells, for example, US Pat. Nos. 3,036,959, 4,015,533, 3,275,610, and European Patent 1
No. 5123, pyridine, methylene chloride, 1,2-
A purification method using a solvent such as propylene carbonate, chloroform, and 1,2-dichloroethane is described. Japanese Patent Application Laid-Open No. 177894/1995 crushes bacterial cells with a high-pressure homogenizer and separates polyhydroxyalkanoate. A method of treating the separated polyhydroxyalkanoate with an enzyme bleach is disclosed. Recently, a method for producing a polyhydroxyalkanoate containing a 3-hydroxybutyric acid unit by chemical synthesis without using a fermentation method has been reported.

[0007] Polylactic acid can be produced by using lactic acid obtained by a chemical synthesis method or a fermentation method as a raw material, for example, lactide, followed by ring-opening polymerization, or by direct polymerization of lactic acid. The polymer from glycols and aliphatic carboxylic acids can be produced, for example, from succinic acid and butanediol, and the molecular weight can be adjusted by urethane bonds or carbonate bonds as needed. In the present invention, there are several methods for adding glass fibers to the aliphatic polyester. When the aliphatic polyester is melt-extruded using an extruder, a glass fiber roving is passed through a die, the periphery of the glass fiber roving is coated with an aliphatic polyester by a method similar to the electric wire coating, and then cooled and solidified to a predetermined length. By cutting into pieces, a pellet-shaped molding material can be produced. In addition, a roving cutter is installed in the hopper of the extruder, and the roving is cut into a predetermined length and dropped at a predetermined speed to the extruder hopper. Is maintained at a desired value, and at the same time, the aliphatic polyester is melt-transferred in the extruder, and at the same time, the glass fibers are uniformly dispersed in the aliphatic polyester, extruded into strands, cooled, solidified and cut into pellet-shaped molding materials. Can also. It is also possible to blend a chopped strand-like glass fiber having a length of 2 to 10 mm and an aliphatic polyester at a predetermined ratio in advance and drop the mixture into an extruder to form a pellet-shaped molding material. . In addition to the above, a chopped glass fiber strand and an aliphatic polyester may be dry blended to form a molding material.

Further, a molded article included in the present invention is:
Even without using an extruder as described above, an aliphatic polyester and glass fiber can be mixed into a molded product as it is in a molding machine such as an injection molding machine. For example, a roving cutter is installed at a supply port, and the glass fiber roving is cut into a predetermined length and supplied to a predetermined supply port, and at the same time, a predetermined amount of aliphatic polyester is supplied to a material supply port of an injection molding machine, and the inside of the molding machine is supplied. In this method, the aliphatic polyester and glass fiber are mixed to form a molded product as it is. Further, when blending the glass fiber with the aliphatic polyester, the blended pellets having a high glass fiber content and the aliphatic polyester pellets are blended by the same means as described above, and the glass fiber content can be adjusted, A pellet having a high glass fiber content and an aliphatic polyester can be supplied to a molding machine to obtain a molded product having a low glass fiber.

The amount of the glass fiber is from 5 to 60% by weight, preferably from 10 to 50% by weight, from the viewpoint of the mechanical properties, thermal properties and molding process of the molded article. When the glass fiber content is lower than 5% by weight, the effects of imparting rigidity and strength by the glass fibers are not sufficiently exhibited, and a molded article having excellent performance cannot be obtained. If the glass fiber content exceeds 60% by weight, smooth production of the molding material becomes difficult,
Defects such as increased wear of the machine used in each step, difficulty in uniformly dispersing the glass fibers in the molded article, and deterioration of the appearance of the molded article are conspicuous and undesirable. In the aliphatic polyester in the present invention, the content of the resin containing a 3-hydroxybutyric acid unit is 50% by weight or more. The reason is that when a resin other than the resin containing a 3-hydroxybutyric acid unit is a highly flexible resin such as polycaprolactone, polybutylene succinate, polyethylene succinate, or polyester carbonate, and the content thereof is 50% by weight or more, rigidity is reduced. Insufficient molding may not be obtained. In addition, when polylactic acid having high rigidity is used in an amount of 50% by weight or more, the molding cycle time becomes long.

When blending a resin containing a 3-hydroxybutyric acid unit with another aliphatic polyester, a blend pellet may be prepared before blending the glass fiber, or at the same time as blending the glass fiber. good. Alternatively, another aliphatic polyester may be blended after blending glass fibers with a resin containing a 3-hydroxybutyric acid unit. The weight average molecular weight of the resin containing a 3-hydroxybutyric acid unit to be used is 10.0 or less from the viewpoint of melt viscosity and the like.
It is preferably at least 00, more preferably at least 50,000. This is because if the weight average molecular weight of the resin containing the 3-hydroxybutyric acid unit is 10,000 or less, the melt viscosity is too low, and there is a possibility of causing poor appearance such as burrs and sink marks. Further, the aliphatic polyester other than the resin containing a 3-hydroxybutyric acid unit preferably has a weight average molecular weight of 10,000 to 100,000,
More preferably, it is 30,000 to 500,000. This is because if the weight average molecular weight is 10,000 or less, the melt viscosity is too low, and if it is 100,000 or more, the melt viscosity may be too high to make molding such as extrusion and injection impossible.

When the molded article according to the present invention is to be obtained, the mold temperature is preferably from 20 ° C. to 90 ° C., more preferably from 40 ° C. to 80 ° C. This is because the molding cycle time of an aliphatic polyester containing a 3-hydroxybutyric acid unit occupying 50% or more of the aliphatic polyester has the highest crystallization rate at around 60 ° C. Without departing from the scope of the present invention, aliphatic polyesters, in a range that does not impair the object of the present invention,
Depending on the purpose, substances other than glass fibers, such as inorganic fillers, colorants, plasticizers, crystal nucleating agents, lubricants, ultraviolet absorbers, antistatic agents, flame retardants, antioxidants, etc. Can be added.

[0012]

According to the present invention, a molded article which is excellent in moldability, excellent in biodegradability and requires high rigidity is provided.
It can be adapted to various members.

[0013]

(Measurement of weight average molecular weight)

Method: Gel permeation chromatography (GPC) Solvent: chloroform Flow rate: 1 ml / min [Tensile performance] Apparatus: Orientec Tensilon measurement: JIS K 7213 [Bending performance] Apparatus: Orientec Tensilon measurement: JIS K 7203 compliant [Impact test] Equipment: Kamishima Seisakusho impact tester Measurement: JIS K 7110 compliant [Heat deformation temperature measurement] Equipment: Toyo Seiki HDT TESTER Measurement: JIS K 7207 compliant

Examples 1-2 A bacterium, Protomonas e, deposited with 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.
According to the method for separating and purifying poly-3-hydroxybutyric acid described in JP-A-4, after crushing with a high-pressure homogenizer, centrifugation was performed.
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. A glass fiber having a fiber length of 3 mm and a diameter of 13 μm was added to this poly-3-hydroxybutyric acid so as to be 30% and 50% of the total weight, and further, 0.5% of boron nitride was mixed as a crystal nucleating agent. Pelletization was performed using a twin screw extruder. The screw temperature at that time is 150
Performed at １７０170 ° C. The weight average molecular weight at the time of pelletization was 400,000. The pellets thus obtained were subjected to a tensile test, a bending test, an impact test, and a test piece for HDT measurement using an injection molding machine having a mold clamping pressure of 100 ton / cm ² . At that time, the screw temperature was 17
The test was performed at 0 to 190 ° C and a mold temperature of 60 ° C. Table 1 shows the molding cycle time and each measurement result.

Comparative Example 1 Poly-3 purified from cells by the same method as in Examples 1 and 2.
-0.5% by weight of boron nitride was added to -hydroxybutyric acid and pelletized using a screw type twin screw extruder. The screw temperature at that time was performed at 150 to 170 ° C. The weight average molecular weight at the time of pelletization was 400,000. The pellets thus obtained were subjected to a tensile test, a bending test, an impact test, and a test piece for HDT measurement in the same manner as in Examples 1 and 2. Table 1 shows the molding cycle time and various measurement results.

Comparative Examples 2-3 Polylactic acid (trade name: Lacty Part No. 1012, manufactured by Shimadzu Corporation) was prepared in the same manner as in Examples 1-2 to produce a tensile test, a bending test, an impact test, and a test piece for HDT measurement. Was done.
However, the screw temperature of the injection molding machine is 200 to 230.
C., a mold temperature of 30 ° C. and 100 ° C. Table 1 shows the molding cycle time and various measurement results.

COMPARATIVE EXAMPLE 4 Pellets containing 50% by weight of the glass fibers prepared in Examples 1 and 2 were used except that the mold temperature was changed to 100.degree.
Injection molding was performed in the same manner as in Nos. 1 to 2. Table 1 shows the molding cycle time.

Examples 3-4 Polylactic acid (trade name: Lacty Part No. 1012, manufactured by Shimadzu Corporation) or polybutylene succinate (commercially available) was added to the pellets containing 50% by weight of the glass fibers prepared in Examples 1-2. (Bionore # 1001, manufactured by Showa Polymer Co., Ltd.) was blended at 20% of the total weight, and tensile tests, bending tests, impact tests, HD
A test piece for T measurement was produced. At this time, the screw temperature of the injection molding machine was 170 to 190 ° C, and the mold temperature was 60 ° C.
I went in. Table 1 shows the molding cycle time and various measurement results.

Comparative Example 5 19.8% by weight of PHB prepared in Examples 1 and 2; 29.7% by weight of polylactic acid (trade name: Lacty part number 1012; manufactured by Shimadzu Corporation); 50% by weight of glass fiber; Pellets containing 0.5% by weight of boron were prepared, and injection molding was performed in the same manner as in Examples 1 and 2. At this time, the screw temperature of the injection molding machine was 170 to 190 ° C., and the mold temperature was 3
Performed at 0 ° C. Table 1 shows the molding cycle time.

[0020]

[Table 1]

Claims (5)

[Claims] 1. A resin comprising 40 to 95% by weight of an aliphatic polyester and 5 to 60% by weight of glass fiber, wherein said aliphatic polyester contains a 3-hydroxybutyric acid unit.
A biodegradable molding material containing 0% by weight or more. 2. The resin containing 3-hydroxybutyric acid units has a weight average molecular weight of 100,000 or more, and the aliphatic polyester other than the resin containing 3-hydroxybutyric acid units has a weight average molecular weight of 10,000 to 1, , 000,000
The biodegradable molding material according to claim 1, which is: 3. The biodegradable molding material according to claim 1, wherein the resin containing a 3-hydroxybutyric acid unit is poly-3-hydroxybutyric acid. 4. A biodegradable molded article obtained from the biodegradable molding material according to claim 1. 5. Biodegradation comprising 40 to 95% by weight of an aliphatic polyester and 5 to 60% by weight of glass fibers, wherein said aliphatic polyester is a resin containing at least 50% by weight of a resin containing a 3-hydroxybutyric acid unit. Characterized in that the molding material is molded at a mold temperature of 20 ° C to 90 ° C,
Molding method for biodegradable molding materials.