JPH03277656A - Biodegradable resin composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. excellent in physical properties and processability at a low cost by using a polyhydroxyalkanoate (copolymer) or a mixture of the polymers as the main component and compounding it with a specified amt. of a liqid compd. CONSTITUTION:The main component comprising a polyhydroxyalkanoate (copolymer) or a mixture of the polymers (e.g. poly-3-hydroxybutyrate) is compounded with 0.01-60wt.% lipid compd. (e.g. glycerol tributyrate).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biodegradable resin composition. Specifically, the present invention relates to a biodegradable resin composition having excellent physical properties and processability.

(Prior Art) In recent years, due to social demands regarding environmental pollution, polymeric materials that are decomposed in biological systems have been widely studied.

One example of this is the modification of polymers by mixing corn starch with polypropylene, polyethylene, etc. to break down their morphology, but this is not a biodegradable material in an essential sense. It was difficult.

On the other hand, poly-3-hydroxybutyrate (PHB), a polyester that accumulates inside the cells of certain microorganisms,
It has been confirmed that it decomposes in the environment, and it has attracted attention as a detergent that exhibits excellent biodegradability and biocompatibility, and is expected to be used in a variety of fields such as medical materials. however,
PHB has poor impact resistance, hard and brittle physical properties, and
Although it has thermoplastic properties, it has poor processability because it begins to decompose even below its melting point, so it has not been able to be used in a wide range of applications.

In recent years, in an attempt to change these physical properties of P)(B), D-
(-)-3-hydroxybutyrate and D-(-)-3-
Copolymers containing hydroxyvalerate or D(-)-4-hydroxybutyrate as repeating units and methods for producing the same have been studied and developed (for example, JP-A-63-269989). Although the copolymers prepared in this way have properties such as lowering the melting point and imparting flexibility, they require special substrates and reduce the amount of polymer produced by the bacterial cells, so they are used as general-purpose materials. This resulted in an expensive product. As described above, in the conventional fermentation synthesis of copolymers using culture, there are many problems in stably obtaining a large amount of resin having excellent physical properties and processability.

Furthermore, modifications by blending with other polymers, such as polymer blends of PHB and polyethylene oxide (Maruizio Avella and Ezfo
Martuscelli, “Poly-D(->(
3-hydroxybutyrate)/poly(e
thylene oxide) blends: ph
ase diagram, thermalland c
rystallization behavior
, POLYMER, 1988, Vol 29.0ct
over 1731-), polymer blends of PHB and ethylene-propylene rubber or polyvinyl acetate (Pietro Greco and Ezio
Martuscelli, “Crystalliza
tion and thermal behavj.

ur of poly(D(-)-3-hydroxy
butyrate)-based blends”,
POLYMER, 1989, Vol 30. August
ust 1475-), or alternatively modifications by incorporation of sugars, e.g. incorporation of polysaccharides into hydroxybutyrate-hydroxyvalerate copolymers (M, Yasin,
S, J, Ho1land.

A, M, Jolly and B, J
, Tighe, “Polymers for
biodcgradablc mcdfcal
devices 2 Vl, 1lydroxyb
utyrata-hydroxyvaIerata c
opoIyrners: accelerated
degradation of blends
with polysaccharides, old om
atcrials, 1989, Vol 10 Aug
UST 400-) and the like have been studied, but they have not yet achieved a stable polymer composition, economic efficiency, or sufficient improvement in physical properties.

(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 with excellent physical properties and processability.

(Means for Solving the Problems) The above-mentioned composition is characterized in that it contains polyhydroxyalkanoate, a copolymer thereof, or a mixture thereof as a main component, and contains 0.01 to 60% by weight of a lipid compound. This is achieved by a resin composition.

The present invention also provides that the polyhydroxyalkanoate is
This shows a resin composition that is a 3-hydroxyalkanoate. The present invention further provides that the poly-3-hydroxyalkanoate is poly-3-hydroxypropionate,
The resin composition is one or more selected from the group consisting of poly-3-hydroxybutyrate, poly-3-hydroxyvalyrate, and poly-3-hydroxyoctanoate. The present invention also provides a resin composition in which the polyhydroxyalkanoate is poly-4-hydroxyalkanoate. The present invention also provides that poly-4-hydroxyalkaate is poly-4-hydroxyalkaate.
This shows a resin composition that is 4-hydroxybutyrate. The present invention further provides a resin composition in which the lipid compound is one or more compounds selected from the group consisting of monoglycerides, diglycerides, triglycerides, monocarboxylic acid esters, dicarboxylic acid monoesters, and dicarboxylic acid diesters. It shows.

The present invention further provides a resin composition having a glass transition temperature of 0°C or lower.

(Function) In recent years, various studies have been conducted on the existence form of polymers within a bacterial cell, and it has been found that PHB granules within a bacterial cell have a soft amorphous structure (W, P).

Dunlop, A.W., Roberts, J.
Bacteriol,, 114.1271 (19
73)), and it has been confirmed that crystallization progresses when taken out of the bacterial cell. Furthermore, recent analysis results suggest that there is a layer containing lipids on the surface of polymer granules inside the bacterial cells (
“Bacterial Polyester” General Theory, Paper and Paper Technology Association Journal No. 43
See Vol. 10, p23-38. ).

With reference to these findings, the present inventors conducted intensive research to improve the hardness and poor processability properties of polyhydroxyalkanoates represented by PHB, and as a result, they discovered that a lipid compound was mixed into these resins. The inventors have discovered that by doing so, the lipid compound acts as a kind of plasticizing or softening agent for these resins, resulting in a composition that has desirable physical properties at low cost, leading to the present invention.

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

The resin composition of the present invention contains polyhydroquine alkanoate or its copolymer as a main component, and contains no lipid compound.
．． It is characterized by containing 01 to 60% by weight of tzG.

The polyhydroxyalkanoate used in the present invention is one in which the number of carbon atoms in the hydroxyalkanoate monomer is about 3 to 12, such as polyhydroxyalkanoate.
Poly-3-hydroxyalkanoates such as 3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxyvalyrate and poly-3-hydroxyoctanoate, poly-4-hydroxybutyrate, etc. -4-hydroxyalkanoate and the like are preferred, and poly-3-hydroxybutyrate is particularly preferred.

Furthermore, in the present invention, copolymers of polyhydroxyalkanoates can also be suitably used. Examples of the copolymer of polyhydroxyalkanoate include copolymers of 3-hydroxybutyrate and other hydroxyalkanoates having 3 to 12 carbon atoms, specifically (3hydroxybutyrate)-(3 -hydroxypropionate) copolymer (3-hydroxybutyrate)-(3-
Hydroxypropionate) (4-hydroxybutyrate) copolymer (3-hydroxybutyrate))-(3
-hydroxyvalerate) 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-hydroxyheptanony)) −(
3-hydroquine octanony 1-) copolymer (3-
hydroxybutyrate)-(3-hydroxyvalerate)-(3-hydroxyhexanoate)-(3-hydroxyheptanoate)=(3-hydroxyoctanoate)-(3-hydroxyvalerate)- (3-hydroxyvalerate)-(3-hydroquine undecanoate)
Examples include (3-hydroxyvalerate) copolymer (3-hydroxybutyrate)-(4-hydroxybutyrate) copolymer, but are not limited thereto.

Furthermore, mixtures of these polyhydroxyalkanoates or copolymers thereof may also be suitably used in the resin composition of the present invention.

These polyhydroxyalkanoates and copolymers thereof are produced by various microorganisms, as is known, and any of them may be used in the present invention. Furthermore, it may be obtained by so-called chemical synthesis.

Examples of microorganisms that produce polyhydroxyalkanoates include Acinetobacter [Ac1nctobacillus].
torco, Actinomycetus [Acti
nomyeetcs], Alcaligenes [Alc
a I i genesco, Aphanosisse [Aphan
othece], Aquaspirillum CAquaspi
ri l Iumko, Azospirillum [Azospj
ri l l um], Azotobacter [Azotob
actor, Bacillus [Bac411us, Beggiatoa], Beierinckia [Be
1jerinckia, Caulobacter [Caulo]
bacter], riooflex [Ch Iorof
Ch Iorog
1oea, Chromatium [Chromatium,
Taromobacterium [Chromobacterium]
], Clostridium [CIostridium
, Derxia, Ectothiorhodospira, Echerichia, Ferobacillus.
Perrobaci I Ius, Gamphosphaeria, Haemophilus aemophilus, Ha
lobacterium, Hyphomicrobium CH
yphomicrobium, lamprosyteis [
Lamprocytis Co., Lampropedia [Lam
Propedia, Leptospira: Leptosp
ira], Methylobacterium [Methylobacterium
cterium], Methylocystice [Methyl
.

Cystis, Micrococcus [Mi croeoe]
cusco, micrococcus [Mjeroeoleus]
, Microcystis
, Moraxella, Mycoplana, Nitrobacter
bacter, Nitrococc [N1trococc]
usco, Nocardia, Oecanospirillum, Paraeoccus, Photobacterium, Pseudomonas, Rhizobium
biu Tako, Rhodobacter 〇? [hodobacter]
, o dospirillum 0? hodospfrillum]
, Sphaerotilus [5phaerotillus], Spirillum [Spirillum], Spirulina [
5pirulina, Streptomyces [Stre
ptomyces] Syntrophomonas [5yntr
ophhoIIIonas], Thiobacillus [Th1ob
acillus, thiocapsa [Th1ocapsa]
, thiocystis mouth'l"hiocystis],
Thiodiction
, Thiopedia [1゛old opedia, Th1osphaera, Vibrio
Examples include various bacteria belonging to bacterial species such as Xanthobacter, Xanthobacter, and Zoog I oea.

In addition, the number average molecule ffl of these polyhydroxyalkanoates or their copolymers synthesized by fermentation in this way
M n is about 10,000 to 3,000°000, or it is synthesized by fermentation and then has its molecular weight reduced by post-treatment such as heat treatment or γ-ray treatment, for example, a number average molecular weight of 3 ,000 to about 10,000 can also be used.

On the other hand, examples of lipid compounds to be incorporated into these polyhydroxyalkanoates or copolymers thereof include monoglycerides, diglycerides, triglycerides, monocarboxylic acid esters, dicarboxylic acid monoesters, and dicarboxylic acid diesters.

Among these, glycerides include glycerol esters of fatty acids having 2 to 1 g of carbon atoms, such as glycerol monoacetate, glycerol monopropionate, glycerol monobutyrate, glycerol monolaure-1, glycerol mono Monoglycerides like myristate, glyceryl monopalmitate, glycerol monostearate etc., glycerol diacetate, glycerol monopropionate, glycerol diphthylate, glycerol dilaurate, glycerol simiristate, glycerol dipalmitate, glycerol distear Preferred are diglycerides such as glycerol triacetate, glycerol tripropionate, glycerol tributyrate, glycerol trilaurate, glycerol monomyristate, glycerol monopalmitate, glycerol monostearate, and the like.

In addition, as carboxylic acid esters, carbon numbers 2 to 30
An ester consisting of a carboxylic acid and an alkyl having 2 to 30 carbon atoms, specifically, saturated or unsaturated esters such as n-amyl acetate, ethyl propionate, methyl caproate, ethyl crotonate, n-butyl oleate, etc. Monocarboxylic acid esters, saturated or unsaturated dicarboxylic acid monoesters such as monomethyl sebacate, mono-n-butyl maleate, monoethyl terephthalate, and dimethyl sebacate, dimethyl terephthalate, di(2) phthalate, etc.
-ethylhexyl), di-n-octyl phthalate, and other saturated or unsaturated dicarboxylic acid diesters are preferred.

Note that these lipid compounds may be in liquid or solid form at room temperature.

Furthermore, the blending amount of these lipid compounds in the resin composition of the present invention is 0.01 to 60% by weight, preferably 1 to 4% by weight.
It is assumed to be 0% by weight. That is, in the resin composition of the present invention, if the amount of the lipid compound is less than 0.01% by weight, the effect of improving the inherent physical properties of polyhydroxyalkanoate will not be sufficient; This is because if the amount of the compound exceeds 60% by weight, the lipid compound may undergo phase separation, leading to a decrease in physical properties.

In the resin composition of the present invention, these lipid compounds are
It acts as a kind of plasticizer or flexibility imparting agent for the resin (polyhydroxyalkanony 1.), lowering the melting point and glass transition temperature of the resin. Therefore, the resin composition of the present invention has significantly better flexibility than the polyhydroxyalkanoate itself (at 1M degrees (for example, room temperature)), and the heating temperature during processing can be lowered. This eliminates the risk of unnecessary thermal decomposition.Furthermore, since many of the above-mentioned lipid compounds are generally inexpensive, for example, as in JP-A No. 63-269989, it is possible to eliminate the risk of unnecessary thermal decomposition. Compared to polyhydroxyalkanoate copolymers synthesized from expensive carbon sources using microorganisms, the resin composition according to the present invention is considerably more economically advantageous in obtaining similar physical properties. ,
The biodegradability of the resin composition of the present invention in soil etc. does not pose any problems because the blended lipid compound itself is decomposed by enzymes such as esterase, and is inferior to polyhydroxyalkanoate itself. It's something that doesn't exist.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 3 and Reference Example 1 Commercially available poly-3- as polyhydroxyalkanoate
Hydroxybutyre) (Mw = 670°000, manufactured by Aldrich/IC+1) (hereinafter abbreviated as P (3HB)) was redissolved in chloroform and reprecipitated with hexane. On the other hand, glycerol tributyrate (reagent grade, manufactured by Tokyo Kasei ■) (hereinafter abbreviated as GTB) was used as a lipid compound, and these were mixed in chloroform at the predetermined ratio shown in Table 1. A film was formed to a thickness of about 0.05 mm by casting at a temperature of ±2° C.), and then 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 examined by the methods described below. The results are shown in Table 1.

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

Table 1 Mixing ratio (weight ratio) Tm ΔHT
gP (3HB) :GTB ('c) (1/
g) ('C) Comparative example 100:0 177.
1 83.7 1.5 Example 1 80:20
164.5 72.1 -29.4 Example 2 6
0:40 151.1 48.3 Example 3 4
0:60 145.9 36.4 Reference example 1 2
0:80 138.2 20.6 In Table 1, each of Tm, ΔH and Tg is the average value of two data.

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

Table 2 Mixing ratio (weight ratio) Tm ΔHT
gP (3HB) :GTP ('C) (J/
g) ('C) Comparative example 100: Oty7. t
83.7 1.5 Example 4 80:20 1
62.7 72.6 -29.1 Example 5 60:
40 151.3 75.0 Example 6 40:
60 154J 21.1 Reference Example 2 20:
80 150.8 8.6 In Table 2, each of Tm, ΔH and Tg is the average value of two data.

Examples 7 to 12 and Reference Example 3 Glycerol triacetate (reagent grade, manufactured by Tokyo Kasei) (hereinafter abbreviated as GTA) was used instead of GTB as a lipid compound, and the blending ratio with P (3HB) was adjusted to 3. Samples were prepared in the same manner as in Examples 1 to 3 or Comparative Example 1 except for the changes shown in the table, and the melting temperature (T
m), heat of fusion (ΔH), and glass transition temperature (Tg) were investigated by the methods described below. The results are shown in Table 3.

Table 3 Mixing ratio (weight ratio) Tm ΔHT
gP (311B) :GTA ('C) (J
/g) ('C) Comparative example 100:0 177
．． 1 83.7 1.5 Example 7 98:2
176.6 85.7 -2.3 Example 8 9
5:5 176.5 86.9 -2.6 Example 9 90:10 173.5 B7.0
zu, 0 Example 10 80:20 1B1.5
70.0 -22.1 Example 11 60:40
146.0 40.5 -38.0 Example 12
40:60 L32.8 20.9 -71
．． 8 Reference Example 3 20:80 127.0 3.
9 -71.8 In Table 3, each of Tm, ΔH and Tg is the average value of two data.

Examples 13-19 Samples were prepared in the same manner as Examples 7-1.2, except that the blending ratios of P (3HB) and GTA were as shown in Table 4. Then, in order to know the mechanical properties of the obtained sample,
Tensile strength, elongation at break, and Young's modulus were measured by the methods described below. The results are shown in Table 4 and Figures 1-2. For comparison, the mechanical properties of the sample obtained in the above comparative example were also investigated in the same manner.

Blending ratio (weight ratio) 1) (3HB):GTA Comparative example 100:0 Example 13 95:5 Example 14 90:10 Example 15 80:20 Example 16 70:30 Example 17 60:40 Example Ht 50:50 Example 19 40:60 Table 4 Tensile strength Elongation at break (MPa) (%) Young's modulus (MPa) Examples 20 to 21 Glycerol trilaurate (reagent grade, Tokyo Samples were prepared in the same manner as in Examples 1 to 3, except that the mixture ratio with P (3HB) was as shown in Table 5. The melting temperature (Tm), heat of fusion (ΔH), and glass transition temperature (Tg) of the obtained samples were investigated by the methods described below. The results are shown in Table 5.

Table 5 Mixing ratio (weight ratio) Tm ΔHT
gP (311B) :GTL ('C) (J
/g) ('C) Comparative example 100:0 177
．． 1 83.7 1.5 Example 20 91:9
175.4 76J-1,1 Example 21
67:33 176.4 58.5 -1.
5 Examples 22 to 28 P (3HB) redissolved in chloroform and reprecipitated with hexane was used as the polyhydroxyalkanoate, while various compounds shown in Table 6 were used as the lipid compound, and these were mixed at the polymerization ratio. DeP(3HB): lipid compound is 8
Mix in chloroform at a ratio of 0.20 and leave at room temperature (
By casting at 20±2℃), the thickness is approximately 0.
A film was formed to a thickness of 0.05 mm and further dried under reduced pressure to obtain a sample.

The obtained sample was examined for Tg and Young's modulus by the method described below, and was further subjected to a simple flexibility test as described below. 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 in "-2", and the results are shown in Table 6.

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

Melting temperature (T m ) and heat of fusion (ΔH) were determined by DSC measurements. The DSC measurement conditions were as follows: under a nitrogen atmosphere, using a thermal analyzer DSC-50 manufactured by Shimadzu Corporation.
The temperature increase rate was set at 10°C/min.

Glass transition temperature (Tg) Based on DSC Hori determination. The DSC measurement conditions were as follows: Using a thermal analyzer DSC-50 manufactured by Shimadzu Corporation, the temperature was raised by 1 degree to a temperature higher than Tm at a heating rate of 10°C/min in a nitrogen atmosphere, and then immediately replaced with liquid nitrogen. The sample was then placed in a container and rapidly cooled, and the sample was measured again under the same conditions from -100°C.

As a measuring device for tensile strength, elongation at break, and Young's modulus, a newly manufactured Strograph-T manufactured by Toyo Seiki was used, and the cut sample was mounted on a JIS K6301 No. 3 dumbbell (distance between gauge lines 20 mm, parallel part width 5 mm). , at a tensile speed of 20 mm/min. Note that the measurement temperature was 23°C.

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

Flexibility evaluation standard P (3HB) and same level as XP (3H
Slightly better than B) △P Better than (3HB) with greater elongation ○ (Effects of the invention) As stated above, the resin composition of the present invention contains bodhydroquine alkanoate, its copolymer, or a mixture thereof. as a main component, and a lipid compound of 0.01 to 6
It is characterized by containing 0% by weight, and improves the flexibility and processability of polyhydroxyalkanoate. On the other hand, it has the same biodegradability as polyhydroxyalkanoate, and is inexpensive. In order to become something,
It is extremely promising as a medical material or as a polymer material in a wide variety of fields from the standpoint of environmental protection.

In the resin composition of the present invention, the polyhydroxyalkanoate is poly-3-human 0xyalkanoate, and the poly-3-hydroxyalkanoate is poly-3-hydroxypropionate, poly-3-hydroxybutyrate, Poly-3-hydroxyvalerate and poly-3
- hydroxyoctanoate, or polyhydroxyalkanoate is poly-4-hydroxyalkanoate, and poly-4-hydroxyalkanoate is poly-4-hydroxyalkanoate. -hydroxybutyrate, and the lipid compound is one or more compounds selected from the group consisting of monocrycerides, diclycerides, triglycerides, monocarboxylic acid esters, dicarboxylic acid monoesters, and dicarboxylic acid diesters, The physical properties such as flexibility and processability as described above become more excellent.

[Brief Description of the Drawings] ': fS1 is a graph showing the relationship between the blending amount of the lipid compound obtained in the Examples of the present invention and the tensile strength and elongation at break of the resin composition, and Fig. 2 is a graph showing the relationship between the blending amount of a lipid compound and the Young's modulus of a resin composition obtained in an example of the present invention.

Claims (7)

[Claims] (1) A resin composition comprising a polyhydroxyalkanoate, a copolymer thereof, or a mixture thereof as a main component, and containing 0.01 to 60% by weight of a lipid compound. (2) The resin composition according to claim 1, wherein the polyhydroxyalkanoate is poly-3-hydroxyalkanoate. (3) Poly-3-hydroxyalkanoate is poly-3
- one or more selected from the group consisting of -hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxyvalerate and poly-3-hydroxyoctanoate. The resin composition described. (4) The resin composition according to claim 1, wherein the polyhydroxyalkanoate is poly-4-hydroxyalkanoate. (5) Poly-4-hydroxyalkaate is poly-4-
The resin composition according to claim 4, which is hydroxybutyrate. (6) The lipid compound is monoglyceride, diglyceride,
The resin composition according to any one of claims 1 to 5, which is one or more compounds selected from the group consisting of triglycerides, monocarboxylic acid esters, dicarboxylic acid monoesters, and dicarboxylic acid diesters. (7) The resin composition according to any one of claims 1 to 6, which has a glass transition temperature of 0°C or lower.