JP2003113326A - Biodegradable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable resin composition which exhibits biodegradability, has excellent mechanical strength such as modulus of elasticity, etc., excellent long-term durability and can finally be biodegraded. SOLUTION: This biodegradable resin composition comprises 100 parts wt. of a water-insoluble biodegradable resin such as an aliphatic polyester, polyamino acid, polyamide/polyester copolymer, polypeptide, lignin, cellulose, etc., and 0.1-50 parts wt. of a phyllosilicate. The laminar silicate has >=3 nm average interlayer distance of face (001) measured by wide-angle X-ray diffraction measurement method and a part or the whole of the phyllosilicate is dispersed in <=5 layers.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable resin composition containing a water-insoluble biodegradable resin and a layered silicate. More specifically, the biodegradable resin composition has a slow biodegradation rate and excellent mechanical strength. And a thermally stable biodegradable resin composition.

[0002]

2. Description of the Related Art Conventionally, various methods of dispersing inorganic particles in a biodegradable resin have been tried in order to improve properties such as mechanical properties, thermal characteristics, gas barrier properties and molding processability of the biodegradable resin. ing.

For example, Japanese Unexamined Patent Publication No. 9-169893 discloses an aliphatic polyester resin composition comprising an aliphatic polyester resin which is a kind of biodegradable resin and a layered silicate. The composition of layered silicate improves the moldability during injection molding. That is, by increasing the crystallization speed, molding stability during molding is secured. However, the strength, biodegradability and heat resistance of the finally obtained molded body are not improved.

Further, in Japanese Patent Laid-Open No. 2001-89646, a biodegradable resin composition having an average particle size of 1 μm or less and having a layered viscous mineral organized by an organic agent is dispersed in the biodegradable resin. It has been disclosed that the material comprising the composition has sufficiently high rigidity, and the biodegradability rate is also high.

However, although these methods ensure the rigidity and moldability of the structure made of the biodegradable resin composition, the durability of the structure is not sufficient. For example,
Structures that are used for a long period of time in a natural environment must have sufficient durability and must be biodegradable in the end. Further, long-term durability is required for housing members, automobile members, etc., and finally it is required to be able to be recycled by a method with a low environmental load by microbial treatment such as composting and methane fermentation. further,
A material comprising the composition described in the above-mentioned prior art for a food container or the like which is required to have durability and heat resistance that can be used several times, and which is finally treated by a microbial treatment, such as a certain food container. Was difficult to use.

[0006]

In view of the above-mentioned state of the art, it is an object of the present invention to exhibit excellent mechanical strength and thermal properties, a moderately delayed biodegradation rate, and sufficient durability. It is to provide a biodegradable resin composition.

[0007]

A biodegradable resin composition according to the present invention contains 100 parts by weight of a water-insoluble biodegradable resin and 0.1 to 50 parts by weight of a layered silicate, and the layered silicic acid is used. The salt is a layered silicate having an average inter-layer distance of (001) plane of 3 nm or more measured by a wide-angle X-ray diffractometry and a part or all of which is dispersed in 5 layers or less. To do.

In a particular aspect of the present invention, the water-insoluble biodegradable resin is at least one selected from the group consisting of aliphatic polyester, polyamino acid, polyamide / polyester copolymer, polypeptide, lignin and cellulose. Species or derivatives thereof.

In the present invention, montmorillonite and / or swelling mica is preferably used as the layered silicate. In another specific aspect of the present invention, the layered silicate is a layered silicate pretreated with an alkylammonium ion having 6 or more carbon atoms, and the hydroxyl group on the crystal side surface of the layered silicate is chemically combined with a hydroxyl group. It is chemically modified with a chemical substance having a functional group having a binding property or a chemical affinity at the molecular end.

In a more limited aspect of the present invention, the functional group having a chemical bond or affinity with the hydroxyl group is
It is at least one selected from the group consisting of an alkoxy group, an alkoxysilyl group, an epoxy group, a carboxyl group, a hydroxyl group, a maleic anhydride group, an isocyanate group and an aldehyde group.

The present invention will be described in detail below. The layered silicate used in the present invention means a silicate mineral having an exchangeable cation between layers. In layered silicate,
Generally, the thickness is about 1 nm, and the average aspect ratio is about 20-2.
Fine flaky crystals of about 00 are aggregated by ionic bonds.

The type of the layered silicate is not particularly limited, and examples thereof include smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite or nontronite, vermiculite, halloysite, and swelling mica. The layered silicate may be natural or synthetic.

Considering the mechanical strength of the material finally obtained from the biodegradable resin composition and the degrading enzyme barrier property for delaying biodegradation, the shape difference defined by the following formula (1) is considered. Particularly preferred are montmorillonite and swelling mica, which have a large tonic effect.

Shape anisotropy effect = side surface area of flaky crystal / area of principal surface of flaky crystal ... Formula (1) In addition, the side surface and the major surface of the flaky crystal in Formula (1) are as shown in FIG. The side surface A and the main surface B of the flaky crystal 1 in the layered silicate schematically shown in FIG.

The cation exchange capacity of the layered silicate used in the present invention is not particularly limited, but a range of 50 to 200 meq / 100 g is preferable. 50 meq / 100g
If less than 20%, the amount of the cationic surfactant intercalated between the flaky crystals by ion exchange may be small, and the layers may not be sufficiently depolarized.
When it exceeds 0 meq / 100 g, the bonding force between the layers of the layered silicate becomes strong, and it may be difficult to delaminate the flaky crystals.

In the present invention, a layered silicate having an average interlayer distance of (001) plane of 3 nm or more measured by a wide-angle X-ray diffractometry and having 5 or less dispersed layers is used.
By having an average interlayer distance of 3 nm or more and being dispersed in 5 layers or less, the mechanical properties of the material made of the biodegradable resin composition according to the present invention are good, and its degrading enzyme, microorganisms, water, etc. The effect of delaying the biodegradability by is obtained.

In the present specification, the average interlaminar distance of the layered silicate is the average interlaminar distance when the fine flaky crystal is used as a layer. The average interlayer distance of the layered silicate in this specification is a wide-angle X-ray diffractometer (manufactured by Rigaku Corporation, product number: R
It is a value obtained by measuring 2θ of a diffraction peak obtained by diffraction of a laminated surface of a layered silicate in a material according to INP1100) and using the following Bragg's diffraction formula.

Λ = 2 dsin θ where λ = 1.54, d is the interplanar spacing of the layered silicate, that is, the interlayer distance, and θ is the diffraction angle.

The flaky crystals in the layered silicate, that is, the state of exfoliation of the layers, was examined by a transmission electron microscope photograph using a transmission electron microscope (manufactured by JEOL Ltd., product number: JEM-1200EX II). It is determined by observing the exfoliation state of the layered silicate.

The state where the average interlayer distance is 3 nm or more and dispersed in 5 layers or less means that some or all of the fine flaky crystals of the layered silicate are dispersed. , Means that the interaction between layers is weakened. More preferably, it is desirable that the average interlayer distance is 3 nm or more and the particles are dispersed in a single layer.

Furthermore, the average interlayer distance of the layered silicate is 6n.
When it is at least m, the mechanical properties of the material comprising the biodegradable resin composition of the present invention will be further enhanced, and the biodegradability retarding effect due to degrading enzymes, microorganisms, etc. will be even greater. When the average interlayer distance is 6 nm or more, the crystal flakes of the layered silicate are separated into layers, and the interaction between the layers in the layered silicate becomes almost negligible. Therefore, the fine crystal flakes constituting the layered silicate are further dispersed in the resin. As the dispersion state of the layered silicate, 10% by volume or more of the layered silicate is preferably dispersed in 5 layers or less, and more preferably 20% by volume or more is dispersed in 5 layers or less.

If the flaky crystals are dispersed so that the number of laminated flaky crystals of the layered silicate in the biodegradable resin composition is 5 or less, the biodegradable resin composition can be prepared according to the present invention. The effect that the mechanical strength of the material is increased and the biodegradation rate is moderately delayed can be obtained, but it is more preferable that the material is dispersed in 3 layers or less, and further, it is dispersed in a single layer as described above. Is more desirable.

In the present invention, preferably, the carbon number is 6
A layered silicate pretreated with the above alkylammonium ion is used, and the hydroxyl group on the crystal side surface of the layered silicate preferably has a functional group having a chemical bond or a chemical affinity with the hydroxyl group at the molecular end. It is chemically modified with the chemical substances it has.

The compound for pretreatment with the alkylammonium ion having 6 or more carbon atoms is not particularly limited, but it is a primary, secondary, tertiary or quaternary compound.
Any of the grade organic ammonium compounds can be used. Preferred are quaternary ammonium salts, quaternary phosphonium salts and the like, and particularly preferred are quaternary ammonium salts having an alkyl chain having 8 or more carbon atoms. When the alkyl chain having 8 or more carbon atoms is not contained, the alkylammonium ion has strong hydrophilicity, and it becomes difficult to sufficiently depolarize the layers of the layered silicate.

Such organic 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. Compound, decyl trimethyl ammonium compound, dodecyl trimethyl ammonium compound, tetradecyl trimethyl ammonium compound, hexadecyl trimethyl ammonium compound, octadecyl trimethyl ammonium compound, dodecyl dimethyl ammonium compound, dodecyl methyl ammonium compound, dioctadecyl ammonium compound, dioctadecyl dimethyl ammonium compound Onium compounds such bets are exemplified.

Particularly, as the quaternary ammonium salt, for example, lauryl trimethyl ammonium salt, stearyl trimethyl ammonium salt, trioctyl ammonium salt, distearyl dimethyl ammonium salt (hereinafter referred to as DS
(Sometimes abbreviated as DM), di-hardened tallow dimethyl ammonium salt, distearyl dibenzyl ammonium salt, and the like. These organic ammonium compounds may be used alone, or may be used in combination of two or more kinds.
tyl dihydrogenated tal
It may be a mixture of several kinds of alkyl chains such as low ammonium).

Examples of the organically modified layered silicate treated with such a quaternary ammonium salt include the following products. Southern Clay Products, trade name: Cloisit
e10A ... Dimethyl, benzyl, hydr
originated tallow, quaternar
Organic modified montmorillonite Southern clay products Co., Ltd., trade name: Cloisit
e30B ... methyl, tallow, bis-2-
hydroxyethyl, quaternary a
Organic modified montmorillonite substituted by mmmonium chloride Made by Southern Clay Products, Inc., trade name: Cloisit
e93A ... methyl, dihydrogenate
d tallow, ternary ammonium
Organic modified montmorillonite substituted with hydrogen sulphate Further, the above-mentioned "functional group having a chemical bond or chemical affinity with a hydroxyl group" is not particularly limited, but it is necessary that it is a functional group having at least a chemical affinity with a hydroxyl group. And an alkoxy group, an alkoxysil group, an epoxy group, a carboxyl group, a hydroxyl group, a maleic anhydride group, an isocyanate group, an aldehyde group and the like are preferably used.

The chemical substance having a functional group having a chemical bond or chemical affinity with the hydroxyl group at the molecular end may be a compound, an oligomer or a polymer. Examples of such chemical substances include silane compounds, titanate compounds, glycidyl compounds, carboxylic acids or alcohols containing the above functional groups. Preferably, a chemical substance having an alkoxysil group is used. Examples of the compound containing an alkoxysil group include silane coupling agents,
It is represented by the following general formula (2).

[0029]

[Chemical 1]

In the general formula (2), examples of R1 include methyl, ethyl, propyl, isopropyl, hexyl, octadecyl, and alkyl groups having 12 or more carbon atoms. Preferably, an alkyl group having 12 or more carbon atoms is used. That is, the chemical substance that reacts with or hydrogen bonds with the hydroxyl group on the crystal side surface of the layered silicate, when being kneaded with the water-insoluble biodegradable resin, is entangled with the molecular chain of the resin to peel off the crystal flakes. Acts as a physicochemical origin. Therefore, when the molecular weight of the chemical substance increases, the effect of entanglement of molecular chains increases, and as a result, the flaky crystals of the layered silicate are more easily exfoliated.

In addition, R1 may contain a reactive functional group at the molecular end in addition to the above-mentioned functional group having a chemical bond or a chemical affinity with a hydroxyl group. Examples of such a reactive functional group include an aminopropyl group, N-β (aminoethyl) γ-aminopropyl group, vinyl group and the like. Further, the above-mentioned functional group having chemical bondability or chemical affinity with the hydroxyl group also acts in the same manner as this reactive functional group.

Substitution by reacting a suitable reagent that reacts with the reactive functional group with a silane coupling agent having the reactive functional group or with a layered silicate pretreated with the silane coupling agent. The group R1 can be chain-extended, whereby the effect of the above entanglement of the molecular chains is further enhanced, and the flaky crystals of the layered silicate are more easily exfoliated. The reagent that reacts with the reactive functional group is not particularly limited. The chain extension of the substituent R1 may be achieved by directly reacting the water-insoluble biodegradable resin used as the matrix resin with the reactive functional group in the chemical substance.

As the above-mentioned reactive functional group, a vinyl group, an amino group or an epoxy group is particularly preferably used. In this case, the amino group and the epoxy group also act as the above-mentioned “functional group having chemical bondability or chemical affinity with the hydroxyl group”.

When a vinyl group is used as the reactive functional group, it is bound to a reagent having a vinyl group or an alkyl group,
A chemical bond can be easily formed by heat, a radical initiator, ultraviolet rays, an electron beam, or the like. When an amino group is used as the reactive functional group, a chemical bond is formed with a reagent having an isocyanate group, a maleic anhydride group, a carboxyl group, or a carbonyl group by using heat, an acid, a base or the like. It can be easily formed. When an epoxy group is used as the reactive functional group, a chemical bond can be easily formed by reacting with a reagent having a hydroxyl group and by using heat, acid, or base.

In the above-mentioned general formula (2), R2, R
3 and R4 may not have a functional group having a chemical bond or a chemical affinity with a hydroxyl group, in which case R
2, R3 and R4 are not particularly limited, and examples thereof include a methyl group, an ethyl group, a methoxy group and an ethoxy group.

Specific examples of the chemical substance having a functional group having a chemical bond or chemical affinity with the hydroxyl group at the molecular end include a silane coupling agent represented by the above general formula (2), for example, Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (βmethoxyethoxy) silane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane,
γ-aminopropyldimethylmethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyldimethylethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, hexyltrimethoxysilane , Hexyltriethoxysilane, N
-Β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, octadecyltrimethoxysilane, octadecyl Triethoxysilane, γ-
Methacryloxypropylmethyldimethoxysilane, γ-
Methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyltriethoxysilane, γ-glyce Cidoxypropyltriethoxysilane etc. can be mentioned.

In the present invention, the layered silicate includes
An organically modified layered silicate is preferably used. The organically modified layered silicate is a layered silicate in which the layers of the layered silicate are pretreated with the above-described alkylammonium ion having 6 or more carbon atoms.

Generally, the crystal flakes of the layered silicate (1) are tetrahedral (1) in which four oxygen ions are coordinated around ions of silicon or the like, such as montmorillonite shown in FIG.
1) or octahedron in which 6 oxygen ions or hydroxyl ions are coordinated around ions such as aluminum (12)
Each of the crystal flakes is bound by the ionic bonding force by the ions such as sodium and calcium arranged on the main surface.

In the layered silicate, sodium ions and calcium ions between the layers can be ion-exchanged with a cationic surfactant such as an alkylammonium salt. By using a highly non-polar cation species such as distearyl dimethyl ammonium salt as the alkyl ammonium salt, the crystal main surface (B) is made non-polar, and the dispersibility of the layered silicate in the non-polar polymer is increased. Is relatively improved.

However, the hydroxyl group present on the crystal side surface (A) remains as a polar site even after the above-mentioned ion exchange, which is one reason why the organized layered silicate cannot be uniformly dispersed in the nonpolar polymer. . In the present invention, the hydroxyl group present on the crystal side surface (A) is chemically modified with a chemical substance having a functional group having a chemical bond or chemical affinity with the hydroxyl group at the end of the molecule, so that the water-insoluble product The compatibility between the degradable resin and the layered silicate is remarkably improved, and the layered silicate can be easily and uniformly dispersed in the polymer.

Further, the above chemical substance that reacts with or hydrogen bonds with the hydroxyl group on the crystal side surface (A) is entangled with the molecular chain of the resin when kneading with the water-insoluble biodegradable resin, thereby pulling the crystal flakes. Acts as a physicochemical point of peeling That is, the stress for peeling off the crystal flakes (= delamination) is much smaller than when the chemical substance is present on the layered silicate (B).

Generally, the more the crystal flakes of the layered silicate are dispersed in the polymer, the remarkably improved the elastic modulus of the composite material of the water-insoluble biodegradable resin and the layered silicate. This phenomenon can be explained by the fact that the area of the interface between the layered silicate and the resin increases as the dispersion of the crystal flakes increases. That is, since the molecular motion of the polymer is restrained at the bonding surface between the polymer and the inorganic crystal, the mechanical strength such as the elastic modulus of the polymer is increased, so that the higher the dispersion ratio of the crystal flakes, the more efficiently the polymer strength is increased. Can be increased.

The water-insoluble biodegradable resin used in the present invention includes aliphatic polyester, polyamino acid,
At least one selected from the group consisting of polyamide / polyester copolymer, polypeptide, lignin, and cellulose, or a derivative thereof can be used. More specifically, as the aliphatic polyester, polyethylene succinate obtained by polycondensation of glycol and aliphatic dicarboxylic acid, polybutylene succinate, polyhexamethylene succinate, polyethylene adipate, polyhexamethylene adipate, poly Butylene adipate, polyethylene oxalate, polybutylene oxalate, polyneopentyl oxalate, polyethylene sebacate, polybutylene sebacate, polyhexamethylene sebacate and the like can be mentioned. Plural kinds of these may be used, or two or more kinds of copolymers may be used. In addition, the water-insoluble biodegradable resin may contain other components such as aromatic dicarboxylic acid or polyfunctional hydroxyl group and carboxylic acid, as long as these are the main components. .

Further, poly (α-hydroxy acids) such as polyglycolic acid and polylactic acid or copolymers thereof, and poly (ω-) such as poly (ε-caprolactone) and poly (β-propiolactone). -Hydroxyalkanoate), poly (3-hydroxybutyrate), poly (3
-Hydroxyvalbarate), poly (3-hydroxycaprate), poly (3-hydroxyheptanoate), poly (3-hydroxyoctanoate) such as
-Hydroxyalkanoates) and aliphatic polyesters such as poly (4-hydroxybutyrate) may be used.

Commercially available aliphatic polyesters include Lacty (manufactured by Shimadzu Corporation), Lacia (manufactured by Mitsui Chemicals, Inc.), Nature Works (Nature Works) (manufactured by Cargill Dow), Terramac (manufactured by Unitika), and Bionore (Showa High School). Molecule Co., Ltd., Ecoflex
ex) (manufactured by BASF), Biomax (Bioma)
x) (manufactured by du Point), Eastavio (Eas
terBio) (manufactured by Eastman Chemical Co., Ltd.), Enpole (manufactured by Ire Chemical Co., Ltd.), Cell Green (manufactured by Daicel Co., Ltd.), Lunare (manufactured by Nippon Shokubai Co., Ltd.), Bio Green (manufactured by Mitsubishi Gas Chemical Co., Inc.) and the like. . Polyamides include polyaspartic acid, polyγ-glutamic acid, polyamino acids such as poly (ε-lysine), and celluloses include bacterial cellulose, cellulose acetate, and the like, and also chitin, chitosan, β-1, Examples include natural proteins such as 3-glutan, casein collagen, soy protein, and wheat protein.

In the biodegradable resin composition according to the present invention, 0.1 to 50 parts by weight of the layered silicate is mixed with 100 parts by weight of the water-insoluble biodegradable resin. If the mixing ratio of the layered silicate is less than 0.1 part by weight, the effect of increasing the mechanical strength of the material made of the biodegradable resin composition is not sufficient, and if it exceeds 50 parts by weight, the biodegradability is excessively reduced. To do.

The biodegradable resin composition of the present invention contains
Other appropriate additives may be added. Examples of the additives include antioxidants, light stabilizers, ultraviolet absorbers, lubricants, flame retardants, antistatic agents and the like. In addition, a small amount of an additive serving as a crystal nucleating agent may be added to make the crystals finer and uniform the physical properties.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail by giving specific examples and comparative examples of the present invention. The present invention is not limited to the examples below. [Raw materials used] (1) Layered silicate As a comparative example, the following minerals were used as the layered silicate in which interlayer ions were not exchanged with a cationic surfactant.

-Montmorillonite: Southern clay products, product number: CloisiteNa ^{+ The} following minerals were used as the organically modified layered silicate in which interlayer ions were exchanged.・ Quaternary ammonium salt treatment Montmorillonite Southern Clay Products, trade name: Cloisit
e93A ... methyl, dihydrogenate
d tallow, ternary ammonium
Organically modified montmorillonite swellable mica substituted with hydrogen sulphate: swellable mica manufactured by Corp Chemical (trade name: ME-100)

(2) Chemical composition for modifying the crystal side surface (A) The following compositions were used as the chemical composition for modifying the crystal side surface (A).・ Aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) ・ Octadecictrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) ・ Methacryloxytrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
Reagent) -Vinyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., reagent) -γ-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., reagent) -Both-terminal alkoxysilyl polyisobutylene (weight average molecular weight 20,000, Kanebuchi Kagaku) (Product name: Epion)

(3) Water-insoluble biodegradable resin, polybutylene succinate / adipate (IreCh
manufactured by ECOMAL, product name: Enpol) Polylactic acid (manufactured by Shimadzu, product name: Lacty)

(4) For the purpose of grafting an unsaturated bond contained in peroxide methacryloxymethoxysilane or vinyltrimethoxysilane to a water-insoluble biodegradable resin,
The following peroxides were used.・ 2,5-Dimethyl-2,5-bis (t-butylperoxy) hexane (trade name: Perhexa 2 manufactured by NOF Corporation)
5B, half-life 1 minute temperature 180 ° C)

(5) Reactive Reagents The following compounds were used as reagents for chemically reacting the layered silicic acid treated with aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.).・ Stearyl alcohol (made by Wako Pure Chemical Industries, Ltd.) ・ Epichlorohydrin (made by Wako Pure Chemical Industries, Ltd.)

(6) Organic Solvent for Preparing Dispersion Slurry The following organic solvent was used as a solvent for comparison with the prior art. It is used for the purpose of expanding the interlayer distance by impregnating the layers of the organic slurry.・ Xylene (Wako Pure Chemical Industries, reagent)

[Method of Treating Crystal Side (A)] Treated powders A to F and untreated powder were prepared by the following methods. Treated powder A: Organically modified montmorillonite Cloisit
While stirring 500 g of e93A in a Henschel mixer, 100 g of a 2 wt% aqueous solution of aminopropyltriethoxysilane was added dropwise over 3 minutes. After the dropping was completed, stirring was further performed for 10 minutes. The treated powder was held in a vacuum dryer whose temperature was adjusted to 70 ° C., and dried for 8 hours to obtain a treated powder A.

Treated powder B: Treated powder B was prepared by using octadecyltrimethoxysilane instead of aminopropyltrimethoxysilane in the method for producing treated powder A.

Treated powder C: Methacryloxytrimethoxysilane was used in place of aminopropyltrimethoxysilane in the method for producing treated powder A, and treated powder C was used.
Was prepared.

Treated powder C-2: In the process for preparing treated powder A above, treated powder C-2 was prepared by using vinyltrimethoxysilane instead of aminopropyltrimethoxysilane.
Was prepared.

Treated powder C-3: Glycidoxypropyltrimethoxysilane was used in place of aminopropyltrimethoxysilane in the method for producing treated powder A above.
Treated powder C-3 was prepared.

Treated powder C-4: In the method for producing the treated powder A, alkoxy silyl polyisobutylene at both ends was used in place of aminopropyltrimethoxysilane.
Treated powder C-4 was prepared.

Treated powder D: Treated powder D was prepared by using organized swelling mica instead of the organically modified montmorillonite in the method of preparing treated powder A. Treated powder E: In the method for producing the treated powder A, montmorillonite (Cl
Treated powder E was prepared using oisite Na ⁺ ).

Treated powder F: In the method for producing the treated powder A, montmorillonite (Cloisite Na ⁺ ) was used in place of the organically modified montmorillonite, and octadecyltrimethoxysilane was used in place of aminopropyltrimethoxysilane. Treated powder F was prepared.

Untreated powder: Organically modified montmorillonite was used. Reaction of treated powder C-3 with epichlorohydrin: Five times as much epichlorohydrin as glycidoxypropyltrimethoxysilane was reacted.

Reaction of treated powder A with epichlorohydrin and stearyl alcohol: After reacting aminopropyltrimethoxysilane with epichlorohydrin, stearyl alcohol was further added and reacted.

[Method for preparing sample for evaluation] The resin and each of the treated powders were fed into a small extruder (TEX30) manufactured by Japan Steel Works so that the weight ratio was 92.7 / 7.7,
The strands were melt-kneaded at a set temperature of 130 ° C., and the extruded strands were pelletized with a pelletizer. The obtained pellets are hot-pressed with the temperature adjusted to 150 ° C, and the thickness is 2 mm.
Alternatively, a plate-like material having a thickness of 100 μm was formed. When the charge was a liquid, a plunger pump or a gear pump was used so that the mixture was charged from the middle of the extruder to a predetermined mixing ratio.

[Sample Evaluation Method] (Flexural Elastic Modulus) A test piece was cut out from the plate-like material having a thickness of 2 mm, and the method was specified in JIS K7207.
It was measured using a Tensilon tester.

(Biodegradability) The plate-like material having a thickness of 2 mm was cut into about 1 mm square with a cutter, and JISK695 was used.
According to 0, the decomposition rate was calculated by measuring oxygen consumption. Coulometer OM3001 manufactured by Okura Electric Co., Ltd.
Type A was used.

(Examples 1 to 11 and Comparative Examples 1 to 9) The above water-insoluble biodegradable resin and various treated powders are shown in Table 1 below.
A biodegradable resin composition sample was prepared according to the above sample preparation method. The samples of Examples 1 to 11 and Comparative Examples 1 to 9 thus obtained were evaluated according to the above sample evaluation method. The results are shown in Table 2 below.

[0069]

[Table 1]

[0070]

[Table 2]

Comparative Example 1 is an evaluation of the physical properties of a sample extruded with a biodegradable resin alone. The extruded resin alone had a flexural modulus of 0.6 Gpa and a biodegradation rate of 38% after 3 months.

In Comparative Example 2, clay not treated with the cationic surfactant was used. In this case, the dispersion of clay in the prepared sample was insufficient, the average interlayer distance of clay by X-ray diffraction was 2.4 nm, and the layers were not separated and dispersed even by observation with a transmission electron microscope. The flexural modulus was 0.3 Gpa, which was worse than that of the resin alone, and the biodegradation rate was 63%, which was faster than the resin alone.

On the other hand, as shown in Comparative Example 3, in the case of using the layered silicate organically treated with only the cationic surfactant, the average interlayer distance of clay was 3 nm, but It was not peeled off. The flexural modulus was 0.8 Gpa, which was slightly improved as compared with the resin alone, but the biodegradation rate was 65%, which was even faster.

On the other hand, as shown in Examples 1 to 7, when the chemical composition for modifying the crystal side surface (A) was used, the average interlayer distance was 3 mm or more, and the layers were partially peeled. Alternatively, all were dispersed in 5 layers or less. The flexural modulus was twice as much as that of the single biodegradable resin alone, and the biodegradation rate after 3 months was 20 to 30%, which was 1/2 or less of the biodegradable resin alone, and the degradability was delayed. Was there. Further, the flexural modulus was 1.5 times or more as compared with the case where only untreated clay was dispersed, and the degradability after 3 months was delayed. However, it was confirmed that the degradation rate after 6 months was 90% or more, that is, the degradation was almost complete, and that there was no problem in the final biodegradation.

This is because the unsaturated bond at the end of the chemical composition for modifying the crystal side surface (A) is chemically bonded to the water-insoluble biodegradable resin main chain, so that the crystal flakes of the layered silicate are peeled off. It is considered that the dispersion of the crystal flakes proceeded further, and as a result, the biodegradation rate decreased due to the crystallization effect of the resin and the barrier effect of the clay against the enzyme / microorganism. In addition, Example 3 aims at enhancing the effect of peeling off the crystal flakes of the layered silicate by increasing the molecular weight of the chemical composition for treating the layered silicate,
A high flexural modulus and a decrease in biodegradability were observed, and it was confirmed that there was no problem in the final biodegradation rate.

Further, as shown in Example 7, when the layered silicate (swelling mica) having high shape anisotropy is used, the effect of improving the physical properties is further enhanced.

[0077]

The biodegradable resin composition according to the present invention,
100 parts by weight of water-insoluble degradable resin and 0.1% layered silicate
The average interlayer distance of the (001) plane of the layered silicate was 3n measured by wide-angle X-ray diffractometry.
m or more, and part or all of which is dispersed in 5 layers or less, the material composed of the biodegradable resin composition has excellent mechanical strength, sufficient durability, and biodegradability. Can be done.

Particularly, the hydroxyl groups on the crystal side surface of the layered silicate are
When chemically bonded with a hydroxyl group or chemically modified with a chemical substance having a functional group having chemical affinity at the molecular end, the elastic modulus of the water-insoluble biodegradable resin is significantly increased and It is possible to provide a material composed of a biodegradable resin composition having a delayed decomposition rate and capable of exhibiting long-term durability.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the structure of a layered silicate.

FIG. 2 is a diagram schematically showing montmorillonite as an example of a layered silicate.

[Explanation of symbols]

A ... Crystal side B: Crystal main surface

Claims (5)

[Claims] 1. A water-insoluble biodegradable resin 100 parts by weight,
0.1 to 50 parts by weight of layered silicate, and the layered silicate was measured by wide-angle X-ray diffractometry (001)
A biodegradable resin composition, which is a layered silicate having an average inter-layer distance of 3 nm or more, and a part or all of which is dispersed in 5 layers or less. 2. The water-insoluble biodegradable resin is at least one selected from the group consisting of aliphatic polyester, polyamino acid, polyamide / polyester copolymer, polypeptide, lignin and cellulose, or a derivative thereof. The biodegradable resin composition according to claim 1. 3. The biodegradable resin composition according to claim 1, wherein the layered silicate is montmorillonite and / or swellable mica. 4. The layered silicate is a layered silicate pretreated with an alkylammonium ion having 6 or more carbon atoms, and the hydroxyl group on the crystal side surface of the layered silicate has a chemical bond or chemical affinity with the hydroxyl group. The biodegradable resin composition according to claim 1 or 2, which is chemically modified with a chemical substance having a functional group having a property at a molecular end. 5. The functional group having a chemical bond or chemical affinity with the hydroxyl group is selected from the group consisting of an alkoxy group, an alkoxysilyl group, an epoxy group, a carboxyl group, a hydroxyl group, a maleic anhydride group, an isocyanate group and an aldehyde group. The biodegradable resin composition according to claim 4, which is at least one selected.