JPH0768443B2 - Biodegradable resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a biodegradable resin composition. More specifically, the present invention relates to a biodegradable resin composition having excellent physical properties and processability.

(Prior Art) In recent years, polymer materials that are decomposed in a biological system have been widely studied due to social demands for environmental pollution.

As one of them, for example, polymer modification for the purpose of morphological collapse by mixing corn starch with polypropylene, polyethylene, etc. is performed, but this is not a material that is biodegradable in the essential sense. It was difficult.

On the other hand, it has been confirmed that poly-3-hydroxybutyrate (PHB), which is a polyester in which a certain type of microorganism accumulates in the cells, is decomposed in the environment, and has excellent biodegradability and biocompatibility. It has attracted attention as a material to be shown and was expected to be applied to various fields such as medical materials. However, PH
B has poor impact resistance, is hard and brittle in terms of physical properties, and has the property of having thermoplasticity but begins to undergo thermal decomposition even below its melting point, so it has poor processability and has not been widely applicable.

In recent years, as an attempt to change these physical properties of PHB, D-
(−)-3-Hydroxybutyrate and D-(−)-3-
A copolymer containing hydroxyvalerate or D-(−)-4-hydroxybutyrate as a repeating unit and a method for producing the same have been studied and developed (for example, JP-A-63-269989). The copolymer produced in this manner can be used as a general-purpose material because it has characteristics such as lowering of melting point and imparting of flexibility, but it requires a special substrate and lowers the polymer production amount of bacterial cells. It would be expensive. As described above, in the conventional fermentation synthesis of a copolymer by culture, there are many problems in stably obtaining a large amount of a resin having both excellent physical properties and processability.

Furthermore, modification by blending with other polymers, for example, polymer blend of PHB and polyethylene oxide (Maruizio Avella and Ezio Martuscelli, “Poly-D
(−) (3-hydroxybutyrate) / poly (ethylene oxid
e) blends: phase diagram, thermal and crystallizatio
n behavior ", POLYMER, 1988, Vol 29, Octover 1731
-), A polymer blend of PHB and ethylene-propylene rubber or polyvinyl acetate (Pietro Greco and Ezi
o Martuscelli, “Crystallization and thermal behavi
our of poly (D (−)-3-hydroxybutyrate) −base
d blends ", POLYMER, 1989, Vol 30, August 1475-), or modification by blending sugars, for example, blending polysaccharides into hydroxybutyrate-hydroxyvalerate copolymer (M.Yasin, SJHolland, AMJolly and BJTighe,
“Polymers for biodegradable medical devices: VI.Hy
droxybutyrate-hydroxyvalerate copolymers: accelera
ted degradation of blends with polysaccharides ", Bi
omaterials, 1989, Vol 10 August 400-), etc. have been studied, but stable polymer composition or economical efficiency, and further sufficient improvement of physical properties have not been achieved.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a novel biodegradable resin composition. Another object of the present invention is to provide an inexpensive biodegradable resin composition having excellent physical properties and processability.

(Means for Solving the Problems) The above-mentioned various objects are characterized by containing poly-3-hydroxyalkanoate or a copolymer thereof or a mixture thereof as a main component and containing 0.01 to 60% by weight of a lipid compound. It is achieved by the biodegradable resin composition.

The invention also provides that the poly-3-hydroxyalkanoate is from the group consisting of poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxyvalerate and poly-3-hydroxyoctanoate. The present invention shows one or more selected biodegradable resin compositions. The present invention further provides a biodegradable resin composition in which the lipid compound is one or more compounds selected from fatty acid esters. The present invention also provides a biodegradable resin composition in which the lipid compound is one or more compounds selected from the group consisting of monoglycerides, diglycerides and triglycerides. The present invention further shows a biodegradable resin composition having a glass transition temperature of 0 ° C or lower.

(Function) In recent years, various studies have been conducted on the existence forms of polymers in cells, but PHB granules in cells have a soft amorphous structure (WFDunlop.AWRoberds, J.Bac
teriol., 114, 1271 (1973)), and it has been confirmed that crystallization proceeds by taking it out of the cells. Furthermore, recent analysis results provide data suggesting that there is a lipid-containing layer on the surface of polymer granules inside the bacterial cells (introduction to "bacterial polyester",
See Paper and Paper Cooperative Magazine Vol. 43, No. 10, p23-p38. ).

With reference to these findings, the present inventors have conducted diligent research to improve the properties of poly-3-hydroxyalkanoate typified by PHB that is hard and difficult to process, and as a result, lipids have been added to these resins. By mixing the compound,
The inventors of the present invention have found that a lipid compound acts as a kind of plasticity or flexibility-imparting agent for these resins to form a composition having desirable physical properties at low cost.

Hereinafter, the present invention will be described in more detail based on embodiments.

The biodegradable resin composition of the present invention is characterized by containing poly-3-hydroxyalkanoate or a copolymer thereof as a main component, and containing 0.01 to 60% by weight of a lipid compound.

As the poly-3-hydroxyalkanoate used in the present invention, the side chain bonded to the linear carbon atom at the third position in the repeating unit is hydrogen or has 1 to 12 carbon atoms.
An alkyl group to the extent of, for example, poly-3-hydroxypropionate, poly-3-hydroxybutyrate,
Examples thereof include poly-3-hydroxyvalerate and poly-3-hydroxyoctanoate, and poly-3-hydroxybutyrate is particularly preferable. Further, in the present invention, a copolymer of poly-3-hydroxyalkanoate can also be preferably used. Examples of the copolymer of poly-3-hydroxyalkanoate include, for example, copolymers of 3-hydroxybutyrate and other hydroxyalkanoates having 3 to 12 carbon atoms, specifically (3-hydroxybutyrate). )-(3-Hydroxypropionate) copolymer, (3-hydroxybutyrate)-(3-hydroxypropionate)-(4-hydroxybutyrate) copolymer, (3-hydroxybutyrate)-(3-hydroxy Valerate), copolymer, (3-hydroxybutyrate)-(3-hydroxyvalerate)-(3-hydroxyhexanoate)-(3-hydroxyheptanoate) copolymer, (3-hydroxybutyrate)-
(3-hydroxyvalerate)-(3-hydroxyhexanoate)-(3-hydroxyheptanoate)-
(3-hydroxyoctanoate) copolymer, (3-
Hydroxybutyrate)-(3-hydroxyhexanoate)-(3-hydroxyoctanoate) copolymer, (3-hydroxybutyrate)-(3-hydroxyvalerate)-(3-hydroxyheptanoate)-
(3-hydroxyoctanoate) copolymer, (3-
Hydroxybutyrate)-(3-hydroxyvalerate)-(3-hydroxyhexanoate)-(3-hydroxyheptanoate)-(3-hydroxyoctanoate)-(3-hydroxynonanoate)-(3 -Hydroxydecanoate)-(3-hydroxyundecanoate)-(3-hydroxylaurylate) copolymer,
Examples thereof include (3-hydroxybutyrate)-(4-hydroxybutyrate) copolymer and the like, but are not limited thereto.

Furthermore, a mixture of these poly-3-hydroxyalkanoates or copolymers thereof can be preferably used in the biodegradable resin composition of the present invention.

As is known, these poly-3-hydroxyalkanoates and copolymers thereof are produced by various microorganisms, and any of them may be used in the present invention. Further, it may be obtained by so-called chemical synthesis. Examples of the microorganism that produces poly-3-hydroxyalkanoate include Acinetobactor, Acinetobactor, Actinomycetes, and Alcaligen.
es], Aphanothece, Aquaspirillum, Azospirillu
m], Azotobactor, Bacillus [Baci
llus], Beggiatoa [Beggiatoa], Bayerinkia [B
eijerinckia], Colobacter [Caulobacter], Chloroflex [Chlorofrexeus], Chlorogloea [Chlor
ogloea], Chromatium [Chromobacterium], Clostridium [Clost
ridium, Derxia, Ectothiorhodospira, Echeri
chia], Ferrobacillus [Ferrobacillus], Gamposphaeria [Gamphosphaeria], Haemophilus [Haem
ophilus], Halobacterium [Halobacterium], Hyphomicrobium [Hyphomicrobium], Lamplocytis [Lamprocytis], Lampropedia [Lampropedi
a], Leptospira [Leptospira], Methylobacterium [Methylobacterium], Methylocystis [Methyl
ocystis], Micrococcus, Microcoleus, Microcytis
stis], Moraxella [Moraxella], Mycoplana [Myc
oplana], Nitrobacter [Nitrobacter], Nitrococcus [Nitrococcus], Nocardia [Nocardia], Ocyanospirillum [Oceanospirillum], Paracoccus [Paracoccus], Photobacterium [Photobacteriu
m], Pseudomonas [Pseudomonas], Rhizobium [Rh
izobium], Rhodobacter [Rhodobacter], Rhodospirillum [Rhodospirillum], Spherotilus [Sphaerotil]
us], Spirillum, Spiruli
na], Streptomyces [Streptomyces], Syntrophomonas [Syntrophomonas], Thiobacillus [Thioba]
cillus], thiocapsa [Thiocapsa], thiocytisis [Thiocystis], thiodiction [Thiodictyo
n], Thiopedia [Thiopedia], Thiosfera [Thio
sphaera], Vibrio [Vibrio], Zandobacter [Xan
various bacteria belonging to bacterial species such as thobacter] and Zoogloea [Zoogloea].

The number average molecular weight Mn of these poly-3-hydroxyalkanoates or copolymers thereof fermented and synthesized in this manner is about 10,000 to 3,000,000, but after fermented and synthesized, for example, heat treatment or γ Those whose molecular weight is reduced by post-treatment such as linear treatment, for example, those having a number average molecular weight of about 3,000 to 10,000 can also be used.

On the other hand, as the lipid compound to be blended with these poly-3-hydroxyalkanoate or its copolymer, there are monoglyceride, diglyceride, triglyceride, monocarboxylic acid ester, dicarboxylic acid monoester, dicarboxylic acid diester and the like.

Among them, the glycerides are glycerin esters of fatty acids having 2 to 18 carbon atoms, such as glycerol monoacetate, glycerol monopropionate, glycerol monobutyrate, glycerol monolaurate, glycerol monomyristate, glyceryl monoester. Monoglycerides such as palmitate, glycerol monostearate, diglycerides such as glycerol diacetate, glycerol monopropionate, glycerol dibutyrate, glycerol dilaurate, glycerol dimyristate, glycerol dipalmitate, glycerol distearate, etc. Glycerol triacetate, glycerol tripropionate, glycerol tributyrate, glycerol trilaurate, glycerine Over monomyristate, glycerol monopalmitate, triglycerides such as glycerol monostearate is preferred.

Examples of the carboxylic acid esters include esters composed of a carboxylic acid having 2 to 30 carbon atoms and an alkyl having 2 to 30 carbon atoms, specifically, for example, n-amyl acetate, ethyl propionate, methyl caproate, croton. Saturated or unsaturated monocarboxylic acid esters such as ethyl acid and n-butyl oleate, monomethyl sebacate, mono-n-butyl maleic acid and saturated or unsaturated dicarboxylic acid monoesters such as monoethyl terephthalate, and dimethyl sebacate and terephthalate Saturated or unsaturated dicarboxylic acid diesters such as dimethyl acid, di (2-ethylhexyl) phthalate, and di-n-octyl phthalate are preferable.

In addition, these lipid compounds may be liquid or solid at room temperature.

Furthermore, the blending amount of these lipid compounds in the biodegradable resin composition of the present invention is 0.01 to 60% by weight, preferably 1 to
It is set to 40% by weight. That is, in the biodegradable resin composition of the present invention, when the amount of the lipid compound is less than 0.01% by weight, the effect of improving the physical properties originally possessed by poly-3-hydroxyalkanoate is not sufficient. On the other hand, if the blending amount of the lipid compound exceeds 60% by weight, the lipid compound may undergo phase separation and the physical properties may be deteriorated.

In the biodegradable resin composition of the present invention, these lipid compounds are resins (poly-3-hydroxyalkanoate).
To act as a kind of plasticizer or softening agent,
It lowers the melting point and glass transition temperature of the resin.
Therefore, the biodegradable resin composition of the present invention is poly-3-
The flexibility at the use temperature (for example, room temperature) is remarkably improved as compared with the hydroxyalkanoate itself, and the heating temperature at the time of processing is lowered, so that there is no possibility of causing unnecessary thermal decomposition. Further, since many lipid compounds as described above are generally inexpensive, for example, JP-A-63-
269989, the biodegradable resin composition according to the present invention is more similar than the poly-3-hydroxyalkanoate copolymer synthesized by fermentation from an expensive carbon source using a microorganism. It is quite economically advantageous for obtaining the physical properties. In addition, the biodegradability of the biodegradable resin composition of the present invention in soil or the like does not cause any problem because the compounded lipid compound itself is also decomposed by an enzyme such as esterase, and thus poly-3-hydroxyalkanoate It is comparable to itself.

(Examples) Hereinafter, the present invention will be described more specifically with reference to Examples.

Examples 1 to 3 and Reference Example 1 Commercially available poly-3-hydroxybutyrate as poly-3-hydroxyalkanoate (Mw = 670,000, manufactured by Aldrich / ICI [Aldrich / ICI]) (hereinafter, P
(3HB) is abbreviated. ) Was dissolved in chloroform and reprecipitated with hexane, and glycerol tributyrate (reagent grade, Tokyo Kasei Co., Ltd.) was used as a lipid compound.
(Made by GTB) (hereinafter, abbreviated as GTB) and mixed in chloroform at a predetermined ratio shown in Table 1 and cast at room temperature (20 ± 2 ° C) to a thickness of about 0.05.
A film having a thickness of mm was formed and dried under reduced pressure to obtain a sample.

The melting temperature (Tm), heat of fusion (ΔH), and glass transition temperature (Tg) of the sample thus obtained were investigated by the methods described below. The results are shown in Table 1.

Comparative Example For comparison, P (3HB) alone was dissolved in chloroform, cast at room temperature (20 ± 2 ° C.) to form a film with a thickness of about 0.05 mm, and dried under reduced pressure. The melting temperature (Tm), the heat of fusion (ΔH), and the glass transition temperature (Tg) of the sample were examined in the same manner as in Examples 1 to 7. The results are shown in Table 1.

Examples 4 to 6 and Reference Example 2 Examples 1 to 3 except that glycerol tripropionate (reagent grade, manufactured by Tokyo Kasei Co., Ltd.) (hereinafter abbreviated as GTP) is used as the lipid compound instead of GTB. A sample was prepared in the same manner as in Comparative Example 1, and the melting temperature (Tm), heat of fusion (ΔH), and glass transition temperature (Tg) of the obtained sample were investigated by the methods described below. The results are shown in Table 2.

Examples 7 to 12 and Reference Example 3 Glycerol triacetate (reagent grade, manufactured by Tokyo Kasei Co., Ltd.) (hereinafter abbreviated as GTA) was used as the lipid compound in place of GTB, and the mixing ratio with P (3HB) was used. Samples were prepared in the same manner as in Examples 1 to 3 and Comparative Example 1 except that those shown in Table 3 were obtained, and the melting temperature (Tm) of the obtained sample was
The heat of fusion (ΔH) and the glass transition temperature (Tg) were examined by the methods described below. The results are shown in Table 3.

Examples 13 to 19 Samples were prepared in the same manner as in Examples 7 to 12 except that P (3HB) and GTA were mixed in the proportions shown in Table 4. Then, in order to know the mechanical properties of the obtained sample, the tensile strength, breaking elongation and Young's modulus were measured by the methods described below. The results are shown in Table 4 and FIGS. In addition,
For comparison, the mechanical properties of the samples obtained in the above comparative examples were also examined.

Examples 20 to 21 Glycerol trilaurate (reagent grade, manufactured by Tokyo Kasei Co., Ltd.) (hereinafter abbreviated as GTL) was used as the lipid compound instead of GTB, and the blending ratio with P (3HB) was 5th. Samples were prepared in the same manner as in Examples 1 to 3 except that those shown in the table were obtained, and the melting temperature (Tm) and heat of fusion (Δ
H) and glass transition temperature (Tg) were investigated by the methods described below. The results are shown in Table 5.

Examples 22-28 P (3HB) as poly-3-hydroxyalkanoate
Was redissolved in chloroform and reprecipitated with hexane. On the other hand, various compounds shown in Table 6 were used as lipid compounds, and these were used in a weight ratio of P (3HB): lipid compound of 80:
Mix in chloroform at a ratio of 20 to room temperature (20 ± 2
(° C) to form a film having a thickness of about 0.05 mm and further dried under reduced pressure to obtain a sample.

The Tg and Young's modulus of the obtained sample were examined by the methods described below, and a simple flexibility test as described below was performed. The results are shown in Table 6.

The samples obtained in Examples 1, 4, 10 and 21 and Comparative Example were also subjected to the same flexibility test as above, and the results are shown in Table 6 together.

In addition, the measuring method of each characteristic in this specification is as follows.

Melting temperature (Tm) and heat of fusion (ΔH) were measured by DSC. As the DSC measurement conditions, a thermal analyzer DSC-50 manufactured by Shimadzu Corporation was used, and the temperature rising rate was 10 ° C./min in a nitrogen atmosphere.

Glass transition temperature (Tg) By DSC measurement. As the DSC measurement conditions, a thermal analyzer DSC-50 manufactured by Shimadzu Corporation was used, and the temperature was raised once to a temperature of Tm or more at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere, and immediately after that, liquid It was put into nitrogen and quenched, and the test was again measured from −100 ° C. under the same conditions.

Using a Toyo Seiki Seisakusho Strograph-T as a tensile strength, breaking elongation and Young's modulus measuring device, attach a cut sample to JIS K6301 No. 3 dumbbell (between marked lines 20 mm, parallel part width 5 mm) Then, it was measured at a pulling speed of 20 mm / min. The measurement temperature was 23 ° C.

Flexibility test In order to easily compare flexibility, a tester manually pulled or bent the sample, and judged based on the following criteria.

Criteria for evaluation of flexibility Same as P (3HB) × Slightly better than P (3HB) △ Greater than P (3HB) ○ (Effect of invention) As described above, the biodegradable resin composition of the present invention Is a lipid compound containing poly-3-hydroxyalkanoate or a copolymer thereof or a mixture thereof as a main component.
It is characterized by containing 0.01 to 60% by weight, and the flexibility and processability of poly-3-hydroxyalkanoate are improved, while the biodegradability is similar to that of poly-3-hydroxyalkanoate. Since it is available and inexpensive, it is extremely promising as a medical material or a polymer material in various fields widely from the viewpoint of environmental protection.

In the biodegradable resin composition of the present invention, the poly-3-hydroxyalkanoate is poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-.
One or more selected from the group consisting of hydroxyvalerates and poly-3-hydroxyoctanoates, and the lipid compound is one or more selected from fatty acid esters. Further, when the lipid compound is one or more compounds selected from the group consisting of monoglyceride, diglyceride and triglyceride, the above-mentioned physical properties such as flexibility and processability are further improved. .

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the compounding amount of the lipid compound obtained in the examples of the present invention and the tensile strength and breaking elongation of the biodegradable resin composition, and FIG. It is a graph which shows the relationship between the compounding quantity of the lipid compound obtained in the example, and the Young's modulus of the biodegradable resin composition.

Claims (5)

[Claims] 1. A poly-3-hydroxyalkanoate or a copolymer thereof or a mixture thereof as a main component,
A biodegradable resin composition comprising 0.01 to 60% by weight of a lipid compound. 2. A poly-3-hydroxyalkanoate from the group consisting of poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxyvalerate and poly-3-hydroxyoctanoate. The biodegradable resin composition according to claim 1, which is one or more selected. 3. The biodegradable resin composition according to claim 1, wherein the lipid compound is one or more compounds selected from the group consisting of fatty acid esters. 4. The biodegradable resin composition according to claim 1, wherein the lipid compound is one or more compounds selected from the group consisting of monoglycerides, diglycerides and triglycerides. 5. The biodegradable resin composition according to claim 1, which has a glass transition temperature of 0 ° C. or lower.