JP2001089646A - Biodegradable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable resin composition which shows a sufficiently high rigidity and a high biodegradation rate. SOLUTION: This biodegradable resin composition contains a biodegradable resin and a layered clay mineral which is organized by an organizing agent dispersed in the biodegradable resin. Here, the organized layered clay mineral has an average particle size of <=1 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a biodegradable resin composition containing an organized layered clay mineral.

[0002]

2. Description of the Related Art Aliphatic polyester resins, copolymers of aliphatic polyester resins and polyamide resins, and the like are known as resins having biodegradability. These biodegradable resins are decomposed by the action of microorganisms and enzymes, but their biodegradation rates are not always fast. Therefore, it has been conventionally attempted to improve the biodegradation rate by adding a natural resin such as starch. However, since the rigidity and heat resistance of the resin are reduced by the addition of a natural resin such as starch, there is a problem that applicable applications are limited.

As another method for improving the performance by adding an additive to a biodegradable resin, for example, Japanese Patent Application Laid-Open No. 9-1698
A method disclosed in Japanese Patent Publication No. 93 is known. That is, this is a method using a resin composition obtained by adding a layered silicate to a biodegradable polyester resin. According to this publication, by the addition of a layered silicate,
It is said that the crystallization rate of the polyester resin can be increased without impairing the intrinsic property of biodegradability, and as a result, cutting properties, moldability, and the like can be improved. However, the disclosed resin composition has not been improved in rigidity or biodegradation rate, and has not been able to solve the above-mentioned problems.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional technical problems, and provides a biodegradable resin composition having sufficiently high rigidity and a high biodegradation rate. The purpose is to do.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, finely disperse a layered clay mineral organically treated with an organic agent in a biodegradable resin. As a result, it has been found that the rigidity of the biodegradable resin composition can be sufficiently increased, and that the biodegradability rate can be increased, and the present invention has been completed.

That is, the biodegradable resin composition of the present invention comprises a biodegradable resin and a layered clay mineral which has been organically dispersed by an organic agent dispersed in the biodegradable resin. Average particle size of organic layered clay mineral is 1μm
It is characterized by the following.

[0007] In the present invention, the organic agent is preferably an organic onium compound, and the biodegradable resin is at least one selected from the group consisting of aliphatic polyesters, polysaccharides, polypeptides and lignin. It is preferably a resin or a derivative thereof.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in more detail. The biodegradable resin composition of the present invention comprises a biodegradable resin, and a layered clay mineral that has been organically dispersed by an organic agent dispersed in the biodegradable resin, and Average particle size of mineral is 1μm
A composition characterized by the following.

The biodegradable resin used in the present invention is not particularly limited as long as it is a resin that can be decomposed or reduced in molecular weight by microorganisms or enzymes, but is not particularly limited. Aliphatic polyester, polysaccharide, polypeptide, lignin, Preferably, it is a derivative. These resins can basically be used alone as a biodegradable resin. However, in practice, rigidity and / or biodegradation rate are not always sufficient, so that these resins are suitable as the biodegradable resin used in the present invention. It is.

Examples of the aliphatic polyester include polyethylene succinate, polybutylene succinate, polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene oxalate, polybutylene oxalate, and polyhexamethylene oxalate. , Represented by polyethylene sebacate, polybutylene sebacate, etc.
Examples of the polyester include a polyester obtained by a polycondensation reaction between at least one kind of glycol and at least one kind of aliphatic dicarboxylic acid.

As a raw material of the polyester, a polyester obtained by partially adding a trifunctional or higher functional polyol to a glycol as a main component may be used, and an aromatic dicarboxylic acid and / or a tricarboxylic acid may be added to an aliphatic dicarboxylic acid as a main component. What added the polycarboxylic acid of a function or more partially may be used. The aliphatic polyester used in the present invention may be a blend or copolymer of two or more of the above-mentioned polyesters.

In addition to the above aliphatic polyesters, poly (α-hydroxy acids) such as polylactic acid and polyglycolic acid
Or a copolymer thereof, poly (ε-caprolactone),
Aliphatic polyesters such as poly (β-prochiolactone), poly (3-hydroxyvalerate), poly (3-hydroxybutyrate) and poly (3-hydroxycaprate) can also be used as the biodegradable resin. .

The polysaccharide used as the biodegradable resin of the present invention includes cellulose, hemicellulose, chitin, chitosan and the like. These polysaccharides may be polysaccharide derivatives in which at least a part of the molecule is replaced with another chemical substance, or at least a part of the molecule is added with another chemical substance. Examples of cellulose derivatives include methyl cellulose and carboxymethyl cellulose.

The polypeptide used as the biodegradable resin of the present invention includes, for example, collagen and collagen derivatives. Lignin used as the biodegradable resin may be any resin having a phenylpropane skeleton obtained from lignified plants and derivatives thereof, and the method for isolating the lignin is not limited.

The above aliphatic polyesters, polysaccharides, polypeptides and lignins may be used alone or as a mixture of two or more.

The layered clay mineral used in the present invention includes, for example, kaolinites such as kaolinite and halosite; smectites such as montmorillonite, beidellite, saponite, hectorite and mica; and layered clay minerals such as vermiculite. No. The layered clay mineral may be derived from a natural product, a processed product of a natural product, or a synthetic product such as swellable fluorinated mica. The above-mentioned layered clay minerals may be used alone or as a mixture of two or more. The ion exchange capacity is 50 to 2
It is preferably 00meq / 100g.

In the present invention, the term "organization" means that an organic substance is adsorbed and / or bound to the surface and / or interlayer of the above-mentioned layered clay mineral by a physical or chemical method.
The term “organizing agent” refers to an organic substance capable of such adsorption and / or binding, and an organic compound having a polar group that generates an ion in a solvent is usually used.

Such organic agents include organic ammonium compounds, organic phosphonium compounds, organic pyridinium compounds, and organic sulfonium compounds from the viewpoint of reactivity to the layered clay mineral and dispersibility of the layered clay mineral in the biodegradable resin. It is preferable to use an organic onium compound such as a compound. Among them, it is more preferable to use an organic ammonium compound and an organic phosphonium compound, since the generated organic onium ion has good reactivity.

The number of carbon atoms of an organic group bonded to a compound having a lone pair of electrons (for example, nitrogen in an organic ammonium compound) in the above-mentioned organic onium compound is not particularly limited, but the number of carbon atoms in the longest chain organic group is 6 to 6. It is preferably 24, more preferably 6-18.
When the carbon number of the longest chain is less than 6, the effect of organizing the layered clay mineral tends to be insufficient, and when it exceeds 24, the dispersion of the layered clay mineral in the biodegradable resin is insufficient. Tend to be. The number of organic groups bonded to the compound having a lone electron pair in the organic onium compound is one or more and the maximum number of bondings or less. In addition,
This organic group may have a carboxyl group, a hydroxyl group, a thiol group, a nitrile group, or the like.

As the organic ammonium compound used as the organic agent, any of primary, secondary, tertiary and quaternary organic ammonium compounds can be used. Such ammonium compounds include hexyl ammonium compounds, octyl ammonium compounds, decyl ammonium compounds, dodecyl ammonium compounds, tetradecyl ammonium compounds, hexadecyl ammonium compounds, octadecyl ammonium compounds, hexyl trimethyl ammonium compounds, octyl trimethyl ammonium compounds, decyl trimethyl compounds. Ammonium compounds, dodecyl trimethyl ammonium compounds, tetradecyl trimethyl ammonium compounds, hexadecyl trimethyl ammonium compounds, octadecyl trimethyl ammonium compounds, dodecyl dimethyl ammonium compounds, dodecyl methyl ammonium compounds, dioctadecyl ammonium compounds, dioctadecyl dimethyl ammonium compounds, etc. And the like. These organic ammonium compounds may be used alone or in combination of two or more.

The organic formation of the layered clay mineral can be performed, for example, by the method disclosed in Japanese Patent No. 2627194 by the present applicant. That is, it can be performed by ion-exchanging inorganic ions in the layered clay mineral with organic onium ions generated from the above-mentioned organic onium compound (for example, organic ammonium ion in the case of an organic ammonium compound).

When an organic ammonium compound is used, for example, the organic compound can be organized by the following method. That is, when a massive layered clay mineral is used, it is first ground into a powder by a ball mill or the like. Next, this powder is dispersed in water using a mixer or the like to obtain an aqueous dispersion of the layered clay mineral. Separately, an acid such as hydrochloric acid and an organic amine are added to water to prepare an aqueous solution of an organic ammonium compound. By adding and mixing this aqueous solution with the aqueous dispersion of the layered clay mineral, inorganic ions in the layered clay mineral are ion-exchanged with organic ammonium ions generated from an organic ammonium compound. By removing water from this mixture, an organized layered clay mineral can be obtained. As a dispersion medium of the organic ammonium compound and the layered clay mineral, in addition to water, methanol, ethanol, propanol, isopropanol, ethylene glycol, a mixture thereof, a mixture thereof, and a water can also be used.

The biodegradable resin composition of the present invention contains the above-mentioned biodegradable resin and an organized layered clay mineral. The biodegradable resin composition is, for example, a biodegradable resin and an organic resin. The dispersed layered clay mineral can be obtained by dispersing or dissolving the layered clay mineral in a solvent such as water or an organic solvent, and then removing the solvent.

Alternatively, it can also be obtained by mixing the biodegradable resin and the organic layered clay mineral and heating the mixture to a temperature higher than the melting point or softening point of the biodegradable resin. At the time of heating, it is preferable to apply a shearing force to uniformly disperse the organic layered clay mineral, and it is preferable to use an extruder as a means for applying the shearing force while heating. At this time, an organic solvent, oil, or the like can be added, and the biodegradable resin may be crosslinked after or during the dispersion of the layered clay mineral.

In addition to the above method, for example, an organically modified layered clay mineral is added to a monomer that forms a biodegradable resin, and the monomer is polymerized in the presence of the organically modified layered clay mineral to perform biodegradation. It is possible to obtain a conductive resin composition.

The mixing ratio of the biodegradable resin and the organically modified layered clay mineral is preferably from 0.01 to 200 parts by weight, more preferably from 0.1 to 200 parts by weight, based on 100 parts by weight of the former.
1 to 100 parts by weight, particularly preferably 0.1 to 30 parts by weight.
Parts by weight. If the weight part of the layered clay mineral is less than 0.01 part by weight, the rigidity of the biodegradable resin composition and the degree of improvement in the biodegradation rate tend to be insufficient, and on the other hand, when it exceeds 200 parts by weight. However, the biodegradable resin tends to be unable to form a continuous layer, and the rigidity of the biodegradable resin composition may be reduced.

In the present invention, a pigment, a heat stabilizer, a flame retardant, an antioxidant, a weathering agent, a release agent, a plasticizer, a reinforcing agent, as long as the properties of the biodegradable resin composition are not significantly impaired. Etc. can be added.

The organic layered clay mineral can be dispersed in the biodegradable resin by the method described above, and the dispersed layered clay mineral has an average particle size of 1 μm or less. In other words, the layered clay mineral is well-organized with the biodegradable resin because it is organically treated, and when mixing both, one is prevented from aggregating and separating, and the dispersion is effectively performed. In addition, the average particle size of the layered clay mineral dispersed in the biodegradable resin can be reduced to 1 μm or less as described above.

The layered clay mineral has a structure in which clay minerals are layered in a layered manner. However, the biodegradable resin can be inserted between the layers due to the organic treatment. As a result, it becomes possible to disperse the layered clay mineral in the biodegradable resin with an average particle size considerably smaller than 1 μm (for example, an average particle size of several to several hundred nm). On the other hand, a layered clay mineral that has not been subjected to organic treatment is poorly compatible with the biodegradable resin, and the insertion of the biodegradable resin between layers does not occur. It is very difficult to disperse.

In the present invention, the organized layered clay mineral dispersed in the biodegradable resin is 0.01 to 1 μm.
m having an average particle size of 0.05 to
More preferably, it has an average particle size of 1 μm. When the average particle size of the organic layered clay mineral exceeds 1 μm, the rigidity of the biodegradable resin tends not to be sufficiently high.

In the present invention, it is preferable that the biodegradable resin is inserted (intercalated) between the layers of the organized layered clay mineral. The interface between the layered clay mineral and the biodegradable resin is increased by the intercalation, and the reinforcing effect of the layered clay mineral on the biodegradable resin is further improved.

The interlayer distance of the layered clay mineral is preferably expanded by 10 angstroms or more, more preferably 20 angstroms or more, than the original interlayer distance by intercalation. The distance between the layers is more preferably 30 Å or more, particularly preferably 100 Å or more. Also,
Most preferably, the interlayer distance is widened to such an extent that the layer structure of the layered clay mineral disappears. As the interlayer distance increases, the proportion of the biodegradable resin restricted by the layered clay mineral increases, and the reinforcing effect of the layered clay mineral on the biodegradable resin improves.

A feature of the biodegradable resin composition of the present invention described above is that an organic layered clay mineral is used as the layered clay mineral to be added to the biodegradable resin. Further, the organic layered clay mineral dispersed in the biodegradable resin has an average particle size of 1 μm or less.

The average particle size of the organic layered clay mineral is 1
By setting the particle size to μm or less, the interface (contact surface) with the biodegradable resin increases as described above, whereby the proportion of the biodegradable resin whose movement is restricted increases, and the biodegradable resin composition It is considered that the rigidity (flexural modulus, flexural strength, etc.) is improved.

Further, by using an organically modified layered clay mineral, the rate of biodegradation is increased as compared with a case where no layered clay mineral is used or a case where an unorganized layered clay mineral is used. Although the mechanism that exerts this effect is not yet clear, the fact that the layered clay mineral is organic and the layered clay mineral is finely dispersed increases the propagation site of the decomposing bacteria and the like. It is thought that effects such as facilitation of reproduction are brought about.

[0036]

Hereinafter, preferred embodiments of the present invention will be described in more detail, but the present invention is not limited to these embodiments.

Example 1 80 g of sodium montmorillonite (a layered clay mineral manufactured by Kunimine Industries Co., Ltd., trade name: Knipia F) was dispersed in 5000 ml of water at 80 ° C. 17.9 g of decylamine and 4.2 g of concentrated hydrochloric acid were added to 80 ° C. water 2
000 ml, and this solution was added to the montmorillonite dispersion to obtain a precipitate. The precipitate was filtered, washed three times with water at 80 ° C., and freeze-dried to obtain montmorillonite organically treated with decyl ammonium. Hereinafter, this montmorillonite is referred to as C10-Mt.

C10-Mt and polylactic acid (manufactured by Shimadzu Corporation,
Lacti 9000) with a twin screw extruder (manufactured by Nippon Steel Works, T
EX-30αII, L / D = 45.5, screw diameter 30
mm) and melt-kneaded at 160 ° C. The mixing ratio of polylactic acid and C10-Mt is the former 1
The latter was 3.9 parts by weight with respect to 00 parts by weight. Also,
The content of montmorillonite in the obtained composition was 3% by weight in terms of an inorganic amount. Next, when this composition was observed with a transmission electron microscope, C10-M dispersed in the composition was observed.
It was confirmed that t had an average particle size of 100 nm.

The obtained composition was formed into a sheet to form a test piece, which was buried in compost at 60 ° C. to reduce the weight of the composition by 5%, 30%, and 90%. The number of days until it became. Furthermore, a test piece of 150 mm × 10 mm × 6 mm was prepared according to ASTM D-790,
A load was applied at a deformation rate of 1 mm / min, and the flexural modulus and flexural strength were measured.

Example 2 Montmorillonite organically treated with decyltrimethylammonium was obtained in the same manner as in Example 1 except that 22.8 g of decyltrimethylamine was used instead of 17.9 g of decylamine. Hereinafter, this montmorillonite is referred to as C10TM-Mt. Also, C10-
Example 1 except that C10TM-Mt was used instead of Mt
In the same manner as in the above, kneading with polylactic acid was performed using a twin-screw extruder. The mixing ratio of polylactic acid and C10TM-Mt was 4.0 parts by weight with respect to 100 parts by weight of the former, and the montmorillonite content of the obtained composition was 3% by weight in terms of inorganic amount. Next, when the obtained composition was observed with a transmission electron microscope, C10TM-
It was confirmed that Mt had an average particle size of 100 nm. Further, the same test pieces as in Example 1 were prepared and subjected to a biodegradability test, a flexural modulus test and a flexural strength test.

Example 3 Montmorillonite organically treated with octadecyl ammonium was obtained in the same manner as in Example 1 except that 30.7 g of octadecylamine was used instead of 17.9 g of decylamine. Hereinafter, this montmorillonite is referred to as C18-Mt. In addition, kneading with polylactic acid was performed using a twin-screw extruder in the same manner as in Example 1 except that C18-Mt was used instead of C10-Mt. The mixing ratio of polylactic acid and C18-Mt was 4.4 parts by weight of the former with respect to 100 parts by weight of the former, and the content of montmorillonite in the obtained composition was 3% by weight in terms of inorganic amount. Then, when the obtained composition was observed with a transmission electron microscope, it was confirmed that C18-Mt dispersed in the composition had an average particle size of 100 nm. Further, a test piece similar to that of Example 1 was prepared and subjected to a biodegradability test, a flexural modulus test, and a flexural strength test.

Example 4 Montmorillonite organically treated with octadecyltrimethylammonium was obtained in the same manner as in Example 1 except that 35.6 g of octadecyltrimethylamine was used instead of 17.9 g of decylamine. Hereinafter, this montmorillonite is referred to as C18TM-Mt.
In addition, kneading with polylactic acid was performed using a twin screw extruder in the same manner as in Example 1 except that C18TM-Mt was used instead of C10-Mt. The mixing ratio of polylactic acid and C18TM-Mt was 4.5 parts by weight with respect to 100 parts by weight of the former, and the content of montmorillonite in the obtained composition was 3% by weight as an inorganic amount. Next, when the obtained composition was observed with a transmission electron microscope, it was confirmed that C18TM-Mt dispersed in the composition had an average particle diameter of 100 nm. Further, a test piece similar to that of Example 1 was prepared and subjected to a biodegradability test, a flexural modulus test, and a flexural strength test.

(Example 5) In the same manner as in Example 3, C18
-Mt was produced. Next, C18-M was added to a solution prepared by dissolving 19 g of a cellulose derivative (manufactured by Shin-Etsu Chemical Co., Ltd .: cellulose derivative 90SH) in 50 ml of dimethylacetamide.
A dispersion obtained by dispersing t450 mg in dimethylacetamide (10 ml) was added and mixed. Next, a composition was obtained by removing dimethylacetamide as a solvent. Observation of this composition with a transmission electron microscope confirmed that C18-Mt dispersed in the composition had an average particle size of 120 nm. Further, a test piece similar to that of Example 1 was prepared and subjected to a biodegradability test.

(Embodiment 6) In the same manner as in Embodiment 4, C18
TM-Mt was produced. Next, 10 g of a lignin derivative (manufactured by Nippon Paper Industries: Lignin derivative Pearlrex CP)
Was dissolved in 50 ml of dimethylacetamide,
450 mg of C18TM-Mt in dimethylacetamide 1
A dispersion dispersed in 0 ml was added and mixed.
Next, a composition was obtained by removing dimethylacetamide as a solvent. When this composition was observed with a transmission electron microscope, C18TM-Mt dispersed in the composition was analyzed.
Has an average particle size of 120 nm. Further, a test piece similar to that of Example 1 was prepared and subjected to a biodegradability test.

(Comparative Example 1) A test piece similar to that of Example 1 was prepared using polylactic acid which is the same as the polylactic acid used in Examples 1 to 4 and to which no organic montmorillonite was added, and biodegraded. An elasticity test, a flexural modulus test and a flexural strength test were performed.

(Comparative Example 2) Using the same polylactic acid as the polylactic acid used in Examples 1 to 4 and sodium montmorillonite, which is the same as that used in Examples 1 to 4 and is not organized, These were kneaded with a twin-screw extruder in the same manner as in Example 1 to obtain a composition. The mixing ratio of polylactic acid and non-organized sodium montmorillonite was 3.1 parts by weight with respect to 100 parts by weight of the former, and the montmorillonite content of the obtained composition was 3 parts by weight in inorganic amount. %
Met. Observation of this composition with a transmission electron microscope revealed that sodium montmorillonite dispersed in the composition had a particle size of several tens to hundreds of μm (average particle size: 20 μm). Further, a test piece similar to that of Example 1 was prepared and subjected to a biodegradability test, a flexural modulus test, and a flexural strength test.

(Comparative Example 3) A test piece similar to that of Example 1 was prepared using the same cellulose derivative as used in Example 5 except that the organically treated montmorillonite was not added. Was done.

(Comparative Example 4) A test piece similar to that of Example 1 was prepared by using the same lignin derivative as used in Example 6 except that the organic montmorillonite was not added. Was done.

Table 1 shows the results of biodegradability tests, flexural modulus and flexural strength tests of Examples 1 to 6 and Comparative Examples 1 to 4.
Shown in When an organic layered clay mineral (montmorillonite) is added to polylactic acid which is a synthetic polymer (Example 1)
4) The biodegradation rate is higher and the stiffness is higher than when the layered clay mineral is not added (Comparative Example 1) and when the unorganized layered clay mineral is added (Comparative Example 2). I understood. Further, a case where an organic layered clay mineral (montmorillonite) is added to a cellulose derivative which is a natural polymer (Example 5) and a case where an organic layered clay mineral (montmorillonite) is added to a lignin derivative which is a natural polymer. In the case (Example 6), it was found that the biodegradation rate was higher, though not as remarkable as when polylactic acid was used, as compared with the case where the layered clay mineral was not used (Comparative Examples 3 and 4). .

[0050]

[Table 1]

[0051]

As described above, according to the present invention,
It is possible to provide a biodegradable resin composition having sufficiently high rigidity and a high biodegradation rate.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 77/04 C08L 77/04 89/00 89/00 97/00 97/00 (72) Inventor Hirotaka Okamoto 41, Chuo-Yokomichi, Nagakute-cho, Aichi-gun, Aichi-gun, Toyota-Chuo Research Institute, Inc. (72) Inventor Makoto Kato Makoto Kato, 41-Cho, Yakumichi, Nagakute-cho, Aichi-gun, Aichi, Japan 72) Inventor: Atsumitsu Usuki, 41-Cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor: Norio Sato 41-Cho, Yokomichi, Nagakute-machi, Aichi-gun F-term in Toyota Central R & D Laboratories Inc. (reference) 4J002 AB021 AB031 AB051 AD001 AH001 CF031 DJ036 DJ056 EN137 EV297 EW177 FA086 FB086 FD200

Claims (3)

[Claims] Claims: 1. An organic layered clay mineral comprising a biodegradable resin, and a layered clay mineral which is organically dispersed by an organic agent dispersed in the biodegradable resin, wherein the average particle diameter of the organically layered clay mineral is A biodegradable resin composition having a particle size of 1 μm or less. 2. The biodegradable resin composition according to claim 1, wherein the organic agent is an organic onium compound. 3. The biodegradable resin is at least one resin selected from the group consisting of aliphatic polyesters, polysaccharides, polypeptides and lignin, or a derivative thereof. A biodegradable resin composition.