JP2000129143A - Biodegradable molded product, its material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject material having excellent mechanical performances, biodegradability and performances capable of standing a use as a molding material even in a relatively low specific gravity, capable of providing a molded product having a woody handle by mixing a biodegradable resin with a natural organic material. SOLUTION: This material is obtained by mixing (A) a biodegradable resin, preferably an aliphatic polyester containing a poly-3-hydroxybutyric acid unit with (B) 1-60 wt.% of a natural organic material, preferably wood flour and/or cellulose powder. In order to obtain a molded product, preferably the aliphatic polyester containing the poly-3-hydroxybutyric acid unit is mixed with 1-60 wt.% of wood flour and/or cellulose powder having <=5 wt.% water content and molded at 130-250 deg.C. A polyhydroxyalkanoate containing the 3- hydroxybutyric acid unit obtained by a fermentation method using a bacterium such as Alcaligenes, etc., is preferably used as the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable molding material containing a natural organic material such as wood flour or cellulose powder.
The present invention relates to a biodegradable molded article comprising the biodegradable molding material and a method for producing the biodegradable molded article. More specifically, high physical properties such as high rigidity, high shape stability, low specific gravity compared to inorganic compounding materials, and excellent biodegradable wood flour, natural biomaterials such as cellulose powder, etc. The present invention relates to a biodegradable resin molding material, a biodegradable molded product comprising the biodegradable molding material, and a method for producing the biodegradable molded product.

[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. Known biodegradable resins are aliphatic polyesters and starch modified starch.

[0003] Aliphatic polyesters can be produced by a fermentation method using a microorganism, a chemical synthesis method, or the like. The aliphatic polyester obtained by the fermentation method is generally a polyhydroxyalkanoate and usually contains a 3-hydroxybutyric acid unit. However, it has been widely studied that its molecular composition and molar ratio bring out performances suitable for the intended use. ing.
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. With respect to starch, improvement of water resistance and improvement of moldability have been carried out by the modification technology, and application development has been promoted. For applications where high rigidity is required, for example, joining members, rigid daily necessities, other rigid medical, industrial and agricultural materials,
The use of aliphatic polyesters and polylactic acids containing a large amount of 3-hydroxybutyric acid units is expected.

However, aliphatic polyesters and polylactic acids containing a large amount of 3-hydroxybutyric acid units cannot be used due to insufficient rigidity in some applications.
Shape stability at 60 ° C. or higher may be poor depending on molding conditions. Japanese Patent Publication No. Hei 7-37560, Japanese Patent Application No. Hei 10-
Japanese Patent No. 128996 describes a material in which calcium carbonate, magnesium carbonate, glass fiber, and the like are mixed with a biodegradable resin. However, after biodegradation, it is not suitable for applications that dislike the deposition of these inorganic substances. Further, since these inorganic substances have a large specific gravity, the specific gravity of the obtained molded article becomes large, and there is a possibility that the use thereof is limited. In addition, in the case of glass fiber, there is a problem that the screw of the extruder and the barrel are worn due to long-term use. For these reasons, at present, active use of biodegradable resins in fields requiring high rigidity has not been achieved.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and has excellent mechanical performance and biodegradability, and a biodegradable molding material and a molded article comprising the biodegradable molding material. Is to provide

[0006]

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. In other words, by blending a natural organic material such as wood powder and cellulose powder with a biodegradable resin, the mechanical performance and shape stability are improved, and the performance can be sufficiently used as a molding material even at a relatively low specific gravity. It has been found that, when wood powder is used, it is possible to obtain a molded product having a wood-like texture depending on the molding method, and the present invention has been completed.

[0007] The gist of the present invention is to provide (1) a biodegradable molding material comprising a biodegradable resin and a natural organic material, and (2) a biodegradable molding material comprising a biodegradable resin and a natural organic material. And (3) an aliphatic polyester containing poly-3-hydroxybutyric acid units containing 1 to 60 wood flour and / or cellulose powder having a water content of 5% by weight or less.
The present invention relates to a method for producing a biodegradable molded article, which is blended at 130 to 250 ° C by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable resin represented by the present invention refers to a polyhydroxyalkanoate containing a 3-hydroxybutyric acid unit produced by a microorganism, a polylactic acid, a polymer derived from a glycol and an aliphatic carboxylic acid, etc. Starch, modified starch and the like and mixtures thereof are included. Polyhydroxyalkanoates containing 3-hydroxybutyric acid units include, for example, the genera Alcaligenes, Azotobacter, and Methylobact.
erium), Nocardia, Pseudomonas, etc. by a known fermentation method.

Regarding the method of separating and purifying the polyhydroxyalkanoate obtained by the fermentation method, for example, US Pat. Nos. 3,036,959, 4,015,533, 3,275,610, and European Patent No. 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, and JP-A-7-177894 crushes bacterial cells with a high-pressure homogenizer and then 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. Further, 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, a method of ring-opening polymerization after forming lactide, or a method of directly polymerizing 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.

As natural organic materials such as wood flour and cellulose powder shown in the present invention, wood is crushed by a millstone, stamp mill, roll mill, impact mill or the like (preferably removing foreign matter such as bark). And a cellulose powder purified by removing lignin contained in wood flour. The type of wood used as the material is not particularly limited, and may be, for example, rice toga. Natural organic materials such as wood powder and cellulose powder are hygroscopic and contain several parts by weight of moisture when left in the air. When natural organic materials such as wood powder and cellulose powder are blended with the biodegradable resin, it is preferable that the water content of these organic materials be 5 parts by weight or less. Further, the content is preferably 1 part by weight or less. This is because biodegradable resins often show reduced moldability and performance due to water.
This is because such a problem may occur.

In the present invention, when a natural organic material such as wood powder or cellulose powder is blended with the biodegradable resin, it is preferable to carry out melt kneading. This is because the melt-kneading disperses these reinforcing materials evenly in the biodegradable resin, brings out better performance, and reduces the variation in the performance of the product. There are several methods for melt-kneading, and examples thereof include a method of kneading by rotation of a screw using a screw-type extruder and a method of melting, kneading, and granulating by heating in a Henschel mixer.

The molding method of the natural organic material compounding material according to the present invention is not particularly limited, and can be used for general injection molding and extrusion molding. A method of adding additives from a side feed can be included. Natural organic materials such as wood flour and cellulose powder are preferably blended at a ratio of 1 to 60% by weight. Further, the content is preferably 1 to 40% by weight. When the content is less than 1% by weight, the effects of imparting rigidity and imparting strength are not sufficiently exhibited, and a molded article having excellent performance cannot be obtained. On the other hand, if it exceeds 60% by weight, smooth production of the molding material becomes difficult, and disadvantages such as deterioration of the appearance of the molded product are noticeable, which is not preferable.

When the molded article according to the present invention is obtained, the molding is preferably performed at a resin temperature of 130 to 250 ° C., more preferably 140 to 200 ° C. This is because if the temperature is lower than 130 ° C., the biodegradable resin is not sufficiently plasticized or the viscosity is too high, which causes problems such as poor appearance. On the other hand, if the temperature exceeds 250 ° C., deterioration of the biodegradable resin, carbonization of wood powder, etc. become remarkable, and the expected performance may not be obtained. When the molded article according to the present invention is obtained, the temperature of the mold member used for cooling after molding is preferably 20 ° C to 100 ° C, and more preferably 40 ° C to 80 ° C. The reason is that the molding cycle time for injection molding is shortened,
Alternatively, this temperature range is appropriate in order to increase the take-up speed in the case of sheet / film production by extrusion molding.

[0014] Substances other than natural organic materials such as biodegradable resins, wood flours and cellulose powders, such as inorganic fillers, coloring agents, plasticizers, etc., do not depart from the scope of the present invention and do not impair the objects of the present invention. Conventional additives such as an agent, a nucleating agent, a release agent, a lubricant, an ultraviolet absorber, an antistatic agent, a flame retardant, and an antioxidant can be added according to the purpose. The biodegradable molding material of the present invention is injection molding, extrusion molding and other molding methods applicable to thermoplastic resins, industrial, civil engineering, agricultural and fishing materials, machine parts, medical parts, Fibers and the like can be obtained. Particularly specific uses of these molded articles include materials that are impossible or difficult to recover or reuse after use, such as building materials, joining members for civil engineering, medical instruments and equipment, packaging materials for food, medicine, and fragrances, Examples include binding members, shopping bags, compost bags, fishing nets / nonwoven fabrics, clothing fibers, industrial nonwoven fabrics, agricultural film / sheets, and the like.

[0015]

According to the present invention, a molded article having excellent mechanical performance and biodegradability and having high rigidity is provided, and can be applied to various members.

[0016]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Various measurements were performed by the following methods. Specific gravity measurement: Underwater displacement method Tensile test: JIS K 7213 Bending test: JIS K 7203 Deflection temperature under load: JIS K 7207 (Load 1
8.6 kg / cm ² ) Impact strength measurement: JIS K 7110

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. Wood flour with a moisture content of 0.7% was added to this poly-3-hydroxybutyric acid (Shimada Shokai,
Cellulosine 100M) or cellulose powder (KC Floc W100 manufactured by Nippon Paper Industries) was added to 10% by weight (see Table 1), and 0.5% of boron nitride was further mixed as a crystal nucleating agent. Pelletization was performed using an extruder. The resin temperature at that time is 180 ° C
I went in. The pellets thus obtained are clamped at a mold clamping pressure of 10
Using a 0 ton / cm ² injection molding machine, a tensile test, a bending test, an impact test, and a test piece for measuring a deflection temperature under load were performed. At that time, the resin temperature was 185 ° C and the mold temperature was 60.
C. was performed. Various measurements were made, and the test results are shown in Table 1.

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 resin temperature at that time was 180 ° C. The pellets thus obtained were subjected to a tensile test, a bending test, and the same method as in Examples 1 and 2.
An impact test and a test piece for measuring a deflection temperature under load were produced. At that time, the resin temperature was 185 ° C. and the mold temperature was 60 ° C. Various measurements were made, and the test results are shown in Table 1.

Comparative Example 2 Poly-3 purified from cells by the same method as in Examples 1 and 2.
After adding calcium carbonate (NS100, manufactured by Nitto Powder Chemical Co., Ltd.) to hydroxybutyric acid so as to be 30% by weight, and further mixing 0.5% of boron nitride as a crystal nucleating agent, using a screw type twin screw extruder. And pelletized. The resin temperature at that time was 180 ° C. The pellets thus obtained were subjected to a tensile test, a bending test, an impact test, and a test piece for measuring a deflection temperature under load using an injection molding machine having a mold clamping pressure of 100 ton / cm ² . At that time, the resin temperature was 185 ° C. and the mold temperature was 60 ° C. Various measurements were made, and the test results are shown in Table 1.

[0020]

TABLE 1 Example Example Comparative Example Comparative Example Example Comparative Example 1 2 1 2 compounding materials wood flour CP * - CaCO ₃ Amount (parts by weight) 10 10 30 density 1.27 1.27 1.25 1.48 Tensile Properties Tensile strength ^{(kgf / cm 2) 341 370} 330 310 bending properties flexural strength ^{(kgf / cm 2) 554 579} 552 530 flexural modulus ^{(tonf / cm 2) 39 41} 36 44 bar impact strength notched (kgf · cm / cm) 2.3 2.3 2.0 1.3 Deflection temperature under load (℃) 97 101 87 125 CP: Cellulose powder

Continued on the front page F term (reference) 4F071 AA09 AA44 AA73 AF14 AF52 AH12 AH17 BA01 BB05 BB06 BC07 4J002 AB01X AH00X CF03W GA00 GB01 GE00 GG00 GK00 GL00

Claims (7)

[Claims] 1. A biodegradable molding material comprising a biodegradable resin and a natural organic material. 2. The biodegradable molding material according to claim 1, wherein the biodegradable resin is an aliphatic polyester containing a poly-3-hydroxybutyric acid unit. 3. The biodegradable molding material according to claim 1, wherein 1 to 60% by weight of wood powder and / or cellulose powder is blended as a natural organic material. 4. A biodegradable molded article comprising a biodegradable molding material obtained by blending a biodegradable resin with a natural organic material. 5. The biodegradable molded article according to claim 4, wherein the biodegradable resin is an aliphatic polyester containing a poly-3-hydroxybutyric acid unit. 6. The biodegradable molded product according to claim 4, comprising a biodegradable molding material containing 1 to 60% by weight of wood powder and / or cellulose powder as a natural organic material. 7. An aliphatic polyester containing poly-3-hydroxybutyric acid units is blended with 1 to 60% by weight of wood flour and / or cellulose powder having a water content of 5% by weight or less.
A method for producing a biodegradable molded article, comprising molding at 30 to 250 ° C.