JP2019034987A - Aliphatic polyester resin composition and molded body - Google Patents

Abstract

To provide an aliphatic polyester resin composition containing poly(3-hydroxyalkanoate) providing a molded body with enhanced strength, and having improved molding processability, and a molded body by molding the same.SOLUTION: There is provided an aliphatic polyester resin composition containing poly(3-hydroxyalkanoate) and modified nanocellulose. In the modified nanocellulose, a hydroxyl group obtained by cellulose is preferably esterified, and the hydroxyl group obtained by cellulose is preferably esterified by dicarboxylic acid.SELECTED DRAWING: None

Description

  The present invention relates to an aliphatic polyester resin composition containing poly (3-hydroxyalkanoate), which is a biodegradable resin, and a molded body formed by molding the same.

  Conventionally, plastics have been disposable from the viewpoints of ease of processing and use, difficulty of reuse, and sanitary problems. However, as plastics are used and disposed of in large quantities, the problems associated with landfilling and incineration are getting closer. Such problems include, for example, the shortage of landfills, the impact on the ecosystem due to the presence of non-degradable plastic in the environment, the generation of harmful gases during combustion, and global warming due to a large amount of combustion heat. A big load on the environment.

  In recent years, biodegradable plastics have been actively developed as a solution to the problem of plastic waste. In general, biodegradable plastics are 1) microbially-produced aliphatic polyesters such as polyhydroxyalkanoates, 2) chemically synthesized aliphatic polyesters such as polylactic acid and polycaprolactone, and 3) natural products such as starch and cellulose acetate. There are three main types: molecules. Most chemically synthesized aliphatic polyesters do not undergo anaerobic decomposition, so there are restrictions on the decomposition conditions at the time of disposal, and polylactic acid and polycaprolactone have a problem in heat resistance. In addition, starch is non-thermoplastic, brittle, and has poor water resistance.

  On the other hand, among polyhydroxyalkanoates, poly (3-hydroxyalkanoate) (hereinafter abbreviated as P3HA) is excellent in degradability in both aerobic and anaerobic environments and generates toxic gases during combustion. In addition, it is possible to increase the molecular weight of a plastic that can be produced by microorganisms using plant raw materials, and has excellent characteristics such as carbon neutrality without increasing carbon dioxide on the earth. The P3HA is classified as an aliphatic polyester, but the properties of the polymer are greatly different from the above-mentioned chemically synthesized aliphatic polyester and natural polymer, and the property of decomposing under anaerobic and excellent moisture resistance, The fact that high molecular weight is possible is a notable performance. When P3HA is a copolymer, physical properties such as melting point, heat resistance and flexibility can be changed by controlling the composition ratio of the constituent monomers. For this reason, P3HA is expected to be used as a molding material applicable to packaging materials, tableware materials, construction / civil engineering / agriculture / horticultural materials, automobile interior materials, adsorption / carrier / filter materials and the like.

  On the other hand, P3HA has two major problems regarding processability. One is a decrease in molecular weight due to thermal decomposition when heated to a high temperature, and the other is poor processability due to a slow crystallization rate. Among P3HA, polyhydroxybutyrate (hereinafter sometimes abbreviated as PHB) has a high melting point of about 175 ° C. and excellent heat resistance. However, since the processing temperature is high, it is very thermally decomposed during heat processing. This is easy and the molecular weight of the molded body is lowered, so that even a high heat resistance tends to be a brittle molded body.

  On the other hand, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter sometimes abbreviated as PHBH), which is a copolymer of P3HA, is 3-hydroxyhexanoate among the copolymer components. Since the melting point is lowered by increasing the ratio of ate, the temperature during heat processing can be lowered, and processing while suppressing the thermal decomposition and maintaining the molecular weight becomes possible.

  In addition, regarding the slow crystallization rate of P3HA, many studies have been made to add a crystal nucleating agent in order to improve this. Inorganic substances such as boron nitride, ammonium chloride and talc are well known as crystal nucleating agents that can be suitably used.

  By the way, the technique of mixing wood powder and cellulose with biodegradable plastic has been known for a long time. Patent Document 1 and Patent Document 2 disclose that wood powder or cellulose is blended with a biodegradable resin to achieve good biodegradability and mechanical performance. Patent Document 3 discloses providing a card having biodegradability with less deformation during embossing by blending a wood component into a biodegradable resin to produce a sheet base material.

  Wood powder mixed with plastics and softwood, which is a raw material for cellulose, absorb and fix carbon dioxide during its growth, so the use of wood powder and cellulose is expected to prevent global warming. Carbon dioxide immobilization substances are very attractive and are expected to be actively used.

JP-A-5-320524 JP 2000-129143 A JP 2003-1987

  The present invention relates to an aliphatic polyester resin composition containing poly (3-hydroxyalkanoate), which is a biodegradable resin, in which a molded article with improved strength is obtained, and the molding processability is improved, And it aims at providing the molded object formed by shape | molding it.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention improve the strength of the molded product by blending modified nanocellulose with poly (3-hydroxyalkanoate), and further improve molding processability. Has been found to be improved, and the present invention has been completed.

  That is, the first of the present invention relates to an aliphatic polyester resin composition containing poly (3-hydroxyalkanoate) and modified nanocellulose.

  The modified nanocellulose is preferably modified nanocellulose in which the hydroxyl group of cellulose is esterified, more preferably modified nanocellulose in which the hydroxyl group of cellulose is esterified with dicarboxylic acid, and the cellulose has More preferred is a modified nanocellulose in which the hydroxyl group is esterified with succinic acid having an alkyl group or an alkenyl group.

The poly (3-hydroxyalkanoate) has the formula: [—CHR—CH ₂ —CO—O—] (wherein R represents a linear or branched alkyl group having 1 to 15 carbon atoms). It is preferable to include the repeating unit shown, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate). Rate-co-3-hydroxyhexanoate), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate), and poly (3-hydroxybutyrate-co-4-hydroxybutyrate) More preferably, it is at least one selected from the group.

  The content of the modified nanocellulose is preferably 1 to 100 parts by weight with respect to 100 parts by weight of poly (3-hydroxyalkanoate).

  2nd of this invention is related with the molded object formed by shape | molding the said aliphatic polyester resin composition.

  According to the present invention, an aliphatic polyester resin composition containing poly (3-hydroxyalkanoate), in which a molded body with improved strength is obtained and molding processability is improved, and is formed by molding the same. A molded body can be provided.

Photomicrograph of the test piece of Example 1 kneaded three times

The present invention is described in detail below.
The present invention relates to an aliphatic polyester resin composition containing poly (3-hydroxyalkanoate) and modified nanocellulose. In the following, poly (3-hydroxyalkanoate) is referred to as P3HA for short.

(P3HA)
P3HA used in the present invention is a polyester containing a 3-hydroxyalkanoic acid unit as a monomer unit. In particular, the formula: [—CHR—CH ₂ —CO—O—] (wherein R is C _n H _{2n + 1} represents a linear or branched alkyl group, and n is an integer of 1 or more and 15 or less. The polyester may be a homopolymer or a copolymer containing two or more of the repeating units. Such a copolymer is preferable because the melting point can be lower than that of a homopolymer, the temperature at the time of melting can be lowered, and the modification of the modified nanocellulose due to the high temperature can be suppressed.

  In addition, P3HA may be a polyester containing only 3-hydroxyalkanoic acid units as monomer units, but other hydroxyalkanoic acid units (for example, 4-hydroxyalkanes) together with 3-hydroxyalkanoic acid units as monomer units. It may be a copolyester containing acid units). In the copolymerized polyester, the content ratio of the 3-hydroxyalkanoic acid unit among the total hydroxyalkanoic acid units is not particularly limited, but is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more. More preferably, 80 mol% or more is particularly preferable, and 90 mol% or more is most preferable.

  Specific examples of P3HA in the present invention include, for example, PHB [poly (3-hydroxybutyrate) or poly-3-hydroxybutyric acid], PHBH [poly (3-hydroxybutyrate-co-3-hydroxyhexanoate)]. Or poly (3-hydroxybutyric acid-co-3-hydroxyhexanoic acid)], PHBV [poly (3-hydroxybutyrate-co-3-hydroxyvalerate), or poly (3-hydroxybutyric acid-co-3- Hydroxyvaleric acid)], P3HB4HB [poly (3-hydroxybutyrate-co-4-hydroxybutyrate) or poly (3-hydroxybutyric acid-co-4-hydroxybutyric acid)], poly (3-hydroxybutyrate- Co-3-hydroxyoctanoate), or poly (3-hydroxybutyrate-co-3-hydroxyoctane) Decanoate), and the like. Of these, PHB, PHBH, PHBV, and P3HB4HB are preferable, and PHBH is more preferable, as industrially easy production.

  P3HA is preferably a homopolymer or a copolymer containing 3-hydroxybutyrate units from the viewpoints of flexibility and strength. Among these, from the viewpoint of balance between flexibility and strength, it is more preferable that the average composition ratio of 3-hydroxybutyrate units contained in P3HA is 80 mol% to 99 mol%, and 85 mol% to 97 mol%. What is shown is more preferred. If the average composition ratio of the 3-hydroxybutyrate unit is less than 80 mol%, the rigidity tends to be insufficient, and if it exceeds 99 mol%, the flexibility tends to be insufficient.

  In the present invention, P3HA may be used alone or in combination of two or more. When a copolymer such as PHBH is used as P3HA, two or more types of copolymers having different average composition ratios of monomer units such as 3-hydroxybutyrate units can be mixed and used.

  The molecular weight of P3HA used in the present invention is not particularly limited as long as the final molded article is intended for the intended use and exhibits substantially sufficient physical properties. However, if the molecular weight is low, the strength of the molded product tends to be reduced. Conversely, if the molecular weight is high, the workability may be reduced and the processing may be difficult. Therefore, the molecular weight may be determined in consideration of them. From this viewpoint, the range of the weight average molecular weight of P3HA used in the present invention is preferably 50,000 to 3,000,000, and more preferably 100,000 to 1,500,000. In addition, the weight average molecular weight here means what was measured as a molecular weight of polystyrene conversion using gel permeation chromatography (GPC) using chloroform eluent. As a column in the GPC, a column suitable for measuring the molecular weight may be used.

  Although the glass transition temperature of P3HA used by this invention is not specifically limited, -30-10 degreeC is preferable. In the present invention, the glass transition temperature is measured at a rate of temperature increase of 10 ° C./min by differential scanning calorimetry.

  Although it does not specifically limit as a method to manufacture P3HA, For example, the method of producing P3HA with the microorganisms which have P3HA production ability is mentioned. Although it does not specifically limit as such microorganisms, For example, as a PHB producing microbe, in addition to Bacillus megaterium discovered in 1925, Capriavidus necator (former classification: Alcaligenes eutrophus (Alcaligenes eutrophus, Ralstonia Examples include Ralstonia eutropha), Alcaligenes latus, etc. Examples of the copolymer-producing bacteria of 3-hydroxybutyrate and other hydroxyalkanoates include Aeromonas, which are PHBV and PHBH-producing bacteria.・ Aeromonas caviae, Alkalinegenes Yu which is a P3HB4HB producing bacterium In particular, as the PHBH-producing bacteria, Alkaligenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) into which a gene of the PHA synthase group has been introduced in order to increase the productivity of PHBH. (T. Fukui, Y. Doi, J. Bacteriol., 179, p4821-4830 (1997)).

  P3HA can be produced by culturing these microorganisms under appropriate conditions, accumulating P3HA in the cells, and recovering the P3HA. The culture conditions including the type of substrate can be optimized according to the microorganism used. In addition to the microorganisms listed above, P3HA can also be produced by culturing genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced in accordance with the P3HA to be produced.

(Modified nanocellulose)
Next, the modified nanocellulose in the present invention will be described.
Cellulose microfibrils (single cellulose nanofibers) with a width of about 4 nm are present in the plant cell wall as the smallest unit, and these cellulose microfibrils gather to form cellulose fibers to form a plant skeleton. . The term “nanocellulose” as used in the present invention means a cellulose nanofiber obtained by treating a plant material (for example, wood pulp) containing cellulose fibers and unraveling the fibers to a nanosize level (defibrating treatment). It means (CNF).

CNF is a fine fiber obtained by subjecting cellulose fibers to treatment such as mechanical defibration, and is a fiber having a fiber diameter of about 4 to 200 nm and a fiber length of about 5 μm or more. The specific surface area of the CNF, preferably about 70~300m ² / g, more preferably about 70 to 250 ² / g, more preferably about 100 to 200 m ² / g. By increasing the specific surface area of CNF, the contact area increases when the resin composition is combined with P3HA, and the strength of the molded body can be improved. However, when the specific surface area of CNF becomes extremely large, aggregation of CNF tends to occur in the resin composition, and the intended high-strength material may not be obtained.

  The average fiber diameter of CNF is usually about 4 to 200 nm, preferably about 4 to 150 nm, and particularly preferably about 4 to 100 nm. In addition, the average value of the fiber diameter of CNF (also referred to as average fiber diameter, average fiber length, average crystal width, and average crystal length) is an average when measured for at least 50 nanocellulose in the field of view of an electron microscope. Value.

  Although it does not specifically limit as a plant fiber used as a raw material of CNF, For example, pulp obtained from natural plant materials, such as wood, bamboo, hemp, jute, kenaf, cotton, beet, agricultural waste, cloth, paper, rayon, Examples include regenerated cellulose fibers such as cellophane. Examples of wood include Sitka spruce, cedar, cypress, eucalyptus, acacia, and examples of paper include, but are not limited to, deinked waste paper, corrugated waste paper, magazines, copy paper, and the like. . Only one plant fiber may be used alone, or two or more plant fibers may be used in combination.

  Among plant fibers, pulp and fibrillated cellulose obtained by fibrillating pulp are preferable raw materials. Although it does not specifically limit as said pulp, For example, the chemical pulp (craft pulp (KP), sulfite pulp (SP)) obtained by pulping a plant raw material chemically or mechanically or using both together , Semi-chemical pulp (SCP), chemi-ground pulp (CGP), chemi-mechanical pulp (CMP), groundwood pulp (GP), refiner mechanical pulp (RMP), thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), And deinked waste paper pulp, corrugated waste paper pulp, magazine waste paper pulp and the like mainly composed of these pulps. These raw materials can be delignified or bleached as necessary to adjust the amount of lignin in the pulp.

  Among these pulps, kraft pulp derived from softwood having strong fiber strength is preferable, and softwood unbleached kraft pulp (NUKP), softwood oxygen-bleached unbleached kraft pulp (NOKP), and softwood bleached kraft pulp (NBKP) are more preferable.

  Pulp is mainly composed of cellulose, hemicellulose, and lignin. The lignin content in the pulp is not particularly limited, but is usually about 0 to 40% by weight, preferably about 0 to 10% by weight. The lignin content can be measured by the Klason method.

  Examples of a method for defibrating plant fibers and preparing CNF include a method for defibrating cellulose fiber-containing materials such as pulp. As the defibrating method, for example, an aqueous suspension or slurry of a cellulose fiber-containing material is mechanically ground by a refiner, a high-pressure homogenizer, a grinder, a uniaxial or multiaxial kneader (preferably a biaxial kneader), a bead mill or the like. A method of defibration by crushing or beating can be used. You may process combining the said defibrating method as needed. As these defibrating methods, for example, the defibrating methods described in JP2011-213754A and JP2011-195738A can be used.

  The modified nanocellulose used in the present invention refers to CNF in which the hydroxyl group (hydroxyl group of sugar chain) contained in cellulose constituting CNF is chemically modified. In the modified nanocellulose of the present invention, it is not necessary that all the hydroxyl groups of the cellulose constituting CNF are modified, and only a part of the hydroxyl groups of the cellulose constituting CNF may be modified. .

  Specific examples of the modified nanocellulose include hydrophobized CNF in which a hydroxyl group present on the surface of CNF is hydrophobized by modification with an acyl group or an alkyl group; a silane coupling agent having an amino group, or a glycidyl trialkyl ammonium halide. Or modified CNF in which the hydroxyl group present on the surface of CNF is cation-modified by modification of its halohydrin type compound; monoesterification with cyclic acid anhydride such as succinic anhydride, alkyl group or succinic anhydride having alkenyl group Further, modified CNF in which the hydroxyl group present on the surface of CNF is anion-modified by modification with a silane coupling agent having a carboxyl group can be used.

  Among these modified nanocelluloses, modified nanocellulose in which the hydroxyl group of cellulose is esterified is preferable. In such modified nanocellulose, the hydroxyl group of cellulose has saturated fatty acid, unsaturated carboxylic acid, monounsaturated fatty acid, diunsaturated fatty acid, triunsaturated fatty acid, tetraunsaturated fatty acid, pentaunsaturated fatty acid, hexaunsaturated fatty acid. Carboxyl of at least one compound selected from the group consisting of saturated fatty acids, aromatic carboxylic acids, dicarboxylic acids, amino acids, maleimide derivatives having a carboxyalkyl group on the nitrogen atom, and phthalimide derivatives having a carboxyalkyl group on the nitrogen atom Preference is given to modified nanocellulose substituted by a residue in which a hydrogen atom is removed from the group.

  Examples of the saturated fatty acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, pivalic acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, Pentadecyl acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid and the like are preferable.

  As said unsaturated carboxylic acid, acrylic acid, methacrylic acid, etc. are preferable.

  As the monounsaturated fatty acid, crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, ricinoleic acid and the like are preferable. As the diunsaturated fatty acid, sorbic acid, linoleic acid, eicosadienoic acid and the like are preferable. As the triunsaturated fatty acid, linolenic acid, pinolenic acid, eleostearic acid and the like are preferable. The tetraunsaturated fatty acid is preferably selected from stearidonic acid and arachidonic acid. The pentaunsaturated fatty acid is preferably boseopentenoic acid or eicosapentaenoic acid. As the hexaunsaturated fatty acid, docosahexaenoic acid, nisic acid and the like are preferable.

  Examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid (3,4,5-trihydroxybenzenecarboxylic acid), and cinnamic acid (3-phenylprop-2-ene). Acid) and the like are preferable.

  As the amino acid, glycine, β-alanine, ε-aminocaproic acid (6-aminohexanoic acid) and the like are preferable.

  According to a preferred embodiment of the present invention, in the modified nanocellulose, the hydroxyl group of the cellulose is modified to a structure represented by the following formula (1).

  In the formula, X can represent an alkyl group, an alkenyl group, an alkyl group including an aromatic ring, an alkenyl group including an aromatic ring, a cyclic alkyl group, a cyclic alkenyl group, or a monovalent aromatic ring group. The group may have a substituent such as a carboxyl group, a halogen, an amino group, a thiol group, a sulfide group, or a disulfide group.

As the alkyl group, a linear or branched alkyl group having 1 to 30 carbon atoms (—C _n H _2n —) is preferable, and examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl and the like. The number of carbon atoms in the alkyl group is more preferably 1-18.

  The alkenyl group is preferably a linear or branched alkenyl group having 2 to 30 carbon atoms, and examples thereof include vinyl (ethenyl), allyl (propenyl), butenyl, pentenyl, hexenyl and the like. The number of carbon atoms in the alkenyl group is more preferably 6-18. The unsaturated bond of the alkenyl group is not limited to a double bond, and may be a triple bond. Further, it may be a group containing one unsaturated bond or a group containing two or more unsaturated bonds. When the unsaturated bond is a double bond, it may be either a cis isomer or a trans isomer.

  An alkyl group containing an aromatic ring or an alkenyl group containing an aromatic ring is one in which the above-described alkyl group or alkenyl group contains a monovalent or divalent aromatic ring. Examples of aromatic rings include benzene rings, condensed benzene rings (naphthalene rings, pyrene rings, anthracene rings, biphenyl rings, etc.), non-benzene aromatic rings (tropylium rings, cyclopropenium rings, etc.), heteroaromatic rings (pyridine rings). , Pyrimidine ring, pyrrole ring, thiophene ring, etc.).

  The cyclic alkyl group or cyclic alkenyl group is preferably a cyclic alkyl group having 5 to 30 carbon atoms or a cyclic alkenyl group, and examples thereof include cyclopentyl and cyclohexyl.

  Examples of the monovalent aromatic ring group include monovalent groups composed of the above-described aromatic rings.

  X may be a substituent containing a structure formed by living polymerization of at least one monomer selected from the group consisting of an olefin monomer, a styrene monomer, and an acrylic monomer. Examples of acrylic monomers include acrylic acid monomers such as acrylic acid, allyl acrylate, ethyl acrylate, and methyl acrylate, methacrylic acid, allyl methacrylate, ethyl methacrylate, glycidyl methacrylate, vinyl methacrylate, and methacrylic acid. And methacrylic acid monomers such as methyl. The degree of living polymerization is preferably about n = 10 to 100, and more preferably about n = 10 to 30. X may be a substituent containing a structure obtained by block polymerization of an acrylic polymer, a methacrylic polymer or the like.

  X may be a halogen or a substituent containing an amino group. The halogen may be fluorine (F) having water repellency, chemical resistance, and heat resistance. Chlorine (Cl), bromine (Br), iodine ( I). When X contains an amino group, amidation with a functional carboxylic acid derivative is possible, and a modified nanocellulose suitable for preparing a composite material with P3HA is obtained.

X may be a substituent containing a thiol group (—SH), a sulfide group (—SR ² ), or a disulfide group (—SSR ³ ). When these groups are included, various metal nanoparticles (for example, Au) can be adsorbed by chemical bonding, and it becomes possible to produce modified nanocellulose having conductivity and specific light absorption characteristics. R ² or R ^{3 in} these groups is not particularly limited, and examples thereof include the alkylene group, alkenylene group, alkylene group containing an aromatic ring, alkenylene group containing an aromatic ring, and the like.

  Among such modified nanocelluloses, from the viewpoint of improving the strength of the molded product, modified nanocellulose in which the hydroxyl group of cellulose is esterified with dicarboxylic acid is more preferable. When the hydroxyl group of cellulose is monoesterified with dicarboxylic acid, the hydroxyl group is modified to a substituent having a carboxyl group. Thereby, the modified nanocellulose has a carboxyl group. By introducing a carboxyl group into cellulose, it has a structure similar to that of poly (3-hydroxyalkanoate). As a result, the interfacial adhesive strength of modified nanocellulose / poly (3-hydroxyalkanoate) is improved. It is estimated that the strength of the molded body is improved.

  According to a more preferred embodiment of the present invention, in the modified nanocellulose monoesterified with such a dicarboxylic acid, the hydroxyl group of the cellulose is modified to a structure represented by the formula (I).

In formula (I), R ¹ represents a direct bond, a divalent aromatic ring, or a linear or branched alkylene group, alkenylene group, cyclic alkylene group, or cyclic alkenylene group.

  Although it will not specifically limit if it is a compound which has two carboxyl groups in 1 molecule as said dicarboxylic acid, A C2-C30 dicarboxylic acid is preferable and a C4-C30 dicarboxylic acid is preferable. Specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, phthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, Examples thereof include methyl tetrahydrophthalic acid, methyl nadic acid, trimellitic acid, pyromellitic acid, alkenyl succinic acid, dodecenyl succinic acid and the like. Of these, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid are preferred. These various dicarboxylic acids may have a substituent such as an alkyl group or an alkenyl group. Dicarboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Among them, the dispersibility of the modified nanocellulose in P3HA is high, the molded article can be given extremely high strength, the conditions during the esterification reaction are mild, and CNF is hardly damaged, and the heat stability of the modified nanocellulose is high. In view of this point, the dicarboxylic acid is preferably a succinic acid having an alkyl group or an alkenyl group. Succinic acid may have one or two alkenyl groups or alkenyl groups. The alkyl group or alkenyl group preferably has 1 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, and still more preferably 8 to 20 carbon atoms. Specifically, alkyl succinic acid such as octyl succinic acid, dodecyl succinic acid, hexadecyl succinic acid, octadecyl succinic acid; pentenyl succinic acid, hexenyl succinic acid, octenyl succinic acid, decenyl succinic acid, undecenyl succinic acid, dodecenyl succinic acid, Examples thereof include alkenyl succinic acids such as tridecenyl succinic acid, hexadecenyl succinic acid, and octadecenyl succinic acid. These may be used individually by 1 type and may use 2 or more types together.
The ester substitution degree of the modified nanocellulose used in the present invention is not particularly limited, and can be appropriately adjusted from the viewpoint of the strength of the molded product and the molding processability. However, from the viewpoint of uniformly dispersing the modified nanocellulose in P3HA and easily obtaining the effect of modification, it is preferably about 0.05 to 2.0, more preferably about 0.1 to 2.0, About 0.8 is more preferable. In addition, with the said ester substitution degree, it substituted by ester among three hydroxyl groups (2nd-position, the 3rd-position, and the 6th-position hydroxyl group) which exist in the glucose frame | skeleton (glucopyranose unit) which comprises the cellulose in modified | denatured nanocellulose. Shows the number of items (average value). The degree of ester substitution can be calculated by titrating the amount of carboxylic acid generated by adding an alkali and hydrolyzing the ester bond.

  The particle size (mesh diameter) of the modified nanocellulose before kneading with P3HA is not particularly limited and is appropriately adjusted depending on the ability of the kneading apparatus. Usually, the modified nanocellulose is a fine particle from the viewpoint of improving dispersibility. It is desirable. Preferably, it can pass 50 meshes, more preferably it can pass 200 meshes. However, when mixing with a kneading apparatus such as an extruder, the modified nanocellulose particles may be pulverized with a high shear stress depending on the type and conditions of the kneading apparatus even if they cannot pass 50 mesh. Therefore, the particle size of the modified nanocellulose is such that the modified nanocellulose can be charged into the extruder, and the dispersion after kneading does not leave a non-dispersed mass, and the pulverization of the particles proceeds to a level that does not significantly reduce the mechanical properties. If it is, it will not specifically limit.

  In addition, since modified nanocellulose has hygroscopicity, it is preferably dried in advance when blended with P3HA. The drying may be appropriately performed to a level that does not generate bubbles due to water vaporization when the resin composition is thermoformed. Further, when the modified nanocellulose is appropriately dried, it is easily dispersed when kneaded with P3HA. However, when the modified nanocellulose is dried at a high temperature exceeding 160 ° C., the free hydroxyl group in the cellulose degenerates or decreases, and the deterioration proceeds, so the affinity with P3HA and the adhesiveness may deteriorate.

(Method for producing modified nanocellulose)
A method for producing modified nanocellulose by modifying CNF may be in accordance with a conventional method. In particular, a method for producing a modified nanocellulose esterified with a dicarboxylic acid will be described. By reacting an anhydride of dicarboxylic acid (anhydrous dicarboxylic acid) with CNF to form a monoester, Modified nanocellulose having the structure represented can be produced. Use of dicarboxylic anhydride is preferable because monoesterification can be carried out without using a catalyst, and CNF can be efficiently modified.

  At this time, about 0.1 mol or more is preferable with respect to 1 mol of hydroxyl groups in CNF, and, as for the compounding quantity of dicarboxylic anhydride, about 0.3 mol or more is more preferable. By setting the blending amount of the dicarboxylic anhydride within the above range, modified nanocellulose having a desired degree of ester substitution can be obtained.

  Although it does not specifically limit as a reaction solvent at the time of esterifying CNF with dicarboxylic anhydride, For example, aprotic solvents, such as NMP, DMF, and DMAc; Ketone type solvents, such as acetone and methyl ethyl ketone, Ester type solvents, such as ethyl acetate Etc. Among these solvents, NMP and acetone are preferable from the viewpoint of dispersibility of CNF. In addition, when the unreacted dicarboxylic anhydride is not removed after the reaction, it is particularly desirable to use acetone as a solvent so that the solvent is easily removed during mixing with the resin.

  Although it does not specifically limit as reaction temperature at the time of esterifying CNF with dicarboxylic anhydride, For example, about 30-200 degreeC is preferable and about 50-150 degreeC is more preferable.

  After esterifying CNF with dicarboxylic anhydride, unreacted dicarboxylic anhydride may be left as it is, or may be removed as necessary. Moreover, in order to make a solvent easy to remove at the time of mixing with resin, the modified | denatured nano cellulose after esterification reaction may be wash | cleaned with another solvent, and the solvent used at the time of reaction may be removed. Solvents used for washing after the esterification reaction include, for example, ketone solvents such as acetone and methyl ethyl ketone; alcohol solvents such as methanol and ethanol; ester solvents such as ethyl acetate; aprotic such as NMP, DMF, and DMAc A solvent is mentioned. Among these, acetone, methyl ethyl ketone, ethyl acetate and the like are preferable from the viewpoint that the solvent can be easily removed and the modified nanocellulose can be favorably dispersed.

(Content)
Although content of P3HA in the aliphatic polyester resin composition of this invention is not specifically limited, 50 to 99 weight% is preferable, More preferably, it is 60 to 98 weight%, More preferably, it is 70 to 95 weight%.

  In the aliphatic polyester resin composition of the present invention, the content of the modified nanocellulose is not particularly limited, but is preferably 1 to 100 parts by weight, more preferably 1.5 to 60 parts by weight based on 100 parts by weight of P3HA. Part by weight, more preferably 2 to 50 parts by weight. When the content of the modified nanocellulose is less than 1 part by weight, the effect of adding the modified nanocellulose may not be seen. When kneading with a roll forming machine or an open kneader, a large amount of modified nanocellulose can be mixed. However, when kneading is performed with a general-purpose extruder, if the content of the modified nanocellulose exceeds 100 parts by weight, the viscosity of the kneaded product becomes too high and it becomes difficult to function as a thermoplastic resin. May be difficult to implement stably. However, even when the amount exceeds 100 parts by weight, the load on the extruder can be reduced by using low molecular weight, low viscosity P3HA, or by mixing a plasticizer, a lubricant, other low viscosity resin, etc. It is possible to obtain the resin composition of the present invention using an extruder that can be kneaded even by viscosity and can give a composition having homogeneity. In addition, since a resin composition in which a large amount of modified nanocellulose is blended with P3HA and its molded body are finally biodegraded when discarded, a conventional resin composition in which a large amount of an inorganic nucleating agent is blended with P3HA. Compared to the molded product and its molded product, it is excellent in that there is no problem of a residue at the time of disposal.

(Optional component)
Known additives can be added to the resin composition of the present invention as long as the effects of the present invention are not impaired. Specifically, a thickener or a crystal nucleating agent for general-purpose plastics and polylactic acid-based resins can be added as an additive. Such a thickener or crystal nucleating agent is not particularly limited, but for example, carbon black, calcium carbonate, silicon oxide, silicate, zinc white, high-site clay, kaolin, basic magnesium carbonate, mica, talc, Quartz powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride, ammonium chloride, crosslinked polymer polystyrene, rosin metal salt, glass fiber And inorganic fibers such as whiskers and carbon fibers, and organic fibers such as human hair, wool, bamboo fibers, and pulp fibers.

  If necessary, the resin composition of the present invention includes pigments, dyes and other colorants, inorganic or organic particles, antioxidants, UV absorbers and other stabilizers, lubricants, mold release agents, and water repellents. Secondary additives such as antibacterial agents may be blended. These additives may be used individually by 1 type, and may be used in combination of 2 or more type.

  You may mix | blend a plasticizer (lubricant) with the resin composition of this invention in the range which does not inhibit the effect of this invention. By blending a plasticizer, it is possible to reduce the melt viscosity during heat processing, especially during extrusion processing, and to suppress a decrease in molecular weight due to shearing heat generation, etc.In some cases, an improvement in crystallization speed can also be expected. Furthermore, when a film or sheet is obtained as a molded product, extensibility can be imparted.

  Although it does not specifically limit as a plasticizer, For example, an ether plasticizer, ester plasticizer, a phthalic acid plasticizer, and a phosphorus plasticizer are preferable, and an ether plasticizer and ester are excellent from the point of having excellent compatibility with P3HA. A plasticizer is more preferable. Examples of ether plasticizers include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of ester plasticizers include esters of aliphatic dicarboxylic acids and aliphatic alcohols, and examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, sebacic acid, adipic acid, and the like. Examples of aliphatic alcohols include monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-hexanol, n-octanol, 2-ethylhexanol, n-dodecanol, stearyl alcohol; ethylene glycol, 1, 2 -Dihydric alcohols such as propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, polyethylene glycol; glycerin, Trimethylolpropane, it may be mentioned polyhydric alcohols pentaerythritol and the like. Further, the copolymer (di-copolymer, tri-copolymer, tetra-copolymer, etc.) containing a combination of two or more of the above aliphatic dicarboxylic acids and / or aliphatic alcohols, or homopolymers and copolymers thereof are selected. Two or more kinds of blends may be mentioned. Furthermore, the esterified product of hydroxycarboxylic acid is also mentioned. The said plasticizer may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the resin composition of the present invention, a fatty acid amide may be blended within a range that does not impair the effects of the present invention. In the resin composition of the present invention, it is considered that the fatty acid amide can act as a crystal nucleating agent or as an internal lubricant and an external lubricant.

Examples of fatty acid amides include compounds represented by the formula: R ⁴ —C (═O) —NR ⁵ R ⁶ . Here, R < ⁴ >, R < ⁵ >, R < ⁶ > represents a hydrogen atom or a C1-C30 hydrocarbon group each independently. The hydrocarbon group may be saturated or unsaturated. Moreover, the said hydrocarbon group may not have a substituent and may have substituents, such as a hydroxyl group, an alkoxy group, a halogen group, a carboxyl group, an amino group, and an amide group. Furthermore, R ⁴ and R ⁵ or R ⁶ may combine to form a cyclic structure.

  Specific examples of fatty acid amides include palmitic acid amide, stearic acid amide, erucic acid amide (EA), behenic acid amide (BA), ricinoleic acid amide, hydroxy stearic acid amide, N-oleyl palmitic acid amide, N-stearyl elca Acid amide, methylene bis lauric acid amide, methylene bis stearic acid amide, methylene bis hydroxy stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid Examples thereof include amides, ethylene biscaprylic amides, ethylene bishydroxystearic amides, N, N′-distearyl sebacic amides, hexanemethylene bisstearic amides, and the like. One type of fatty acid amide may be used alone, or two or more types may be used in combination.

  The fatty acid amide is preferably a compound having a melting point of about 100 to 150 ° C. (particularly 100 to 120 ° C.). When a fatty acid amide having such a melting point is blended with P3HA having a melting point of 90 ° C. or higher, the crystallization speed is improved in the molding process at a temperature 10 to 30 ° C. higher than the melting point of the P3HA, and the moldability Can be improved.

Of the fatty acid amides, primary amides in which R ⁴ in the above formula represents an aliphatic hydrocarbon group having 1 to 30 carbon atoms (particularly 10 to 20 carbon atoms) and R ⁵ and R ⁶ represent a hydrogen atom are preferred. Among them, behenamide (melting point: 114 ° C.), stearic acid amide (melting point: 102 ° C.), ethylenebisstearic acid amide (melting point: 147 ° C.), hydroxystearic acid amide (107 ° C.), methylol behenic acid amide (melting point: 110 ° C.) Is preferred.

  The content of the fatty acid amide in the resin composition of the present invention is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, and still more preferably 0 with respect to 100 parts by weight of P3HA. 0.5 to 3 parts by weight. By controlling the content of the fatty acid amide within the above range, the moldability of the resin composition tends to be further improved.

(Production method of resin composition)
The resin composition of the present invention can be produced by a known method. For example, P3HA, modified nanocellulose, and other additives can be mixed while being heated and melted. In that case, mixing by mechanical stirring using a single-screw extruder, twin-screw extruder, kneader, gear pump, kneading roll, tank with a stirrer, etc., or static mixing that repeats splitting and merging with a flow guide device A vessel can be applied. More specifically, P3HA, modified nanocellulose, and other additives are melt-kneaded with an extruder, roll mill, Banbury mixer, etc. to form a pellet, and used for molding, containing P3HA and high-concentration modified nanocellulose Examples include a method of preparing a master batch to be prepared in advance, melt-kneading this and P3HA at a desired ratio, and using them for molding. P3HA and modified nanocellulose may be added to the kneader at the same time, or after melting P3HA, the modified nanocellulose may be added to carry out melt kneading of both components.

  The heating and melting is preferably performed at a temperature of 180 ° C. or lower in order to avoid or suppress a decrease in the molecular weight of P3HA due to thermal decomposition, and in order to suppress deterioration of the modified nanocellulose due to a high temperature, the temperature is lower than 160 ° C. It is preferable to implement. A particularly preferred heating and melting temperature is the melting point of P3HA ± 10 ° C. When the resin composition melted at such a temperature is cooled to a temperature below the crystallization temperature of P3HA, the crystallization of the resin is promoted, and the melt has a high viscosity and improved adhesion to the modified nanocellulose. Further, the modified nanocellulose and P3HA have a high affinity, and the fine dispersion of the modified nanocellulose in the resin composition is more preferable.

  The resin composition of the present invention is melt-kneaded as described above, then extruded into a strand shape and then cut into pellets having a particle shape such as a cylindrical shape, an elliptical column shape, a spherical shape, a cubic shape, a rectangular parallelepiped shape, etc. be able to. After the obtained pellets are sufficiently dried at 40 to 80 ° C. to remove moisture, the pellets can be molded by a known molding method, and an arbitrary molded body can be obtained. Examples of the molding method include film molding, sheet molding, injection molding, blow molding, blow molding, fiber spinning, extrusion foaming, and bead foaming.

  Examples of the method for producing a film molded body include T-die extrusion molding, calendar molding, roll molding, and inflation molding. However, the film forming method is not limited to these. Moreover, the film obtained from the resin composition of the present invention can be thermoformed by heating, vacuum formed, and press formed.

  As a method for producing an injection-molded body, for example, an injection molding method such as an injection molding method, a gas assist molding method, or an injection compression molding method generally employed when molding a thermoplastic resin can be employed. In addition to the above methods, an in-mold molding method, a gas press molding method, a two-color molding method, a sandwich molding method, PUSH-PULL, SCORIM, or the like can also be employed in accordance with other purposes. However, the injection molding method is not limited to these.

  The resin composition of the present invention may be processed into a pellet, or a molded body such as a film, a sheet, or a fiber using an extrusion molding machine, or processed into a predetermined shape by injection molding. It is also possible. The pellets are once processed into pellets so that the dispersibility of the modified nanocellulose in P3HA and the adhesion (adhesion) between P3HA and modified nanocellulose are good, and the pellets are then formed into a film or sheet using an extruder. Alternatively, it may be processed into a fiber or the like, or injection molding may be performed. Moreover, if a roll molding machine is used as described above, a film or sheet can be formed by melt-kneading even when the mixing ratio of the modified nanocellulose is high.

  Moreover, when the resin composition of this invention contains a foaming agent, a foaming molded object may be sufficient as a molded object of this invention, and it is good also as a molded foam by making it foam after a process.

  The film or sheet obtained from the resin composition of the present invention is superior in the drawdown property and releasability at the time of melting than the resin composition containing no modified nanocellulose, so that it is easy to perform mold vacuum molding by heating. There are advantages.

  The resin composition of the present invention can be processed into molded articles having various shapes. Examples of the molded body include paper, film, sheet, tube, plate, bar, container, bag, and parts. Further, in order to improve the physical properties of the molded product of the present invention, a molded product composed of a material different from the resin composition of the present invention (for example, fiber, yarn, rope, woven fabric, knitted fabric, nonwoven fabric, paper, Film, sheet, tube, plate, bar, container, bag, component, foam, etc.). The use of the molded article of the present invention is not particularly limited, and can be suitably used in agriculture, fishery, forestry, horticulture, medicine, hygiene, clothing, non-clothing, packaging, automobiles, building materials, and other fields.

  EXAMPLES Next, although this invention is demonstrated further in detail based on an Example, this invention is not restrict | limited only to this Example.

<Molecular weight measurement method>
The weight average molecular weight Mw of PHBH was determined by GPC measurement. The GPC apparatus used LC-10A system (made by Shimadzu Corporation), the column used GPCK-806M (made by Showa Denko), and the column temperature was 40 degreeC. 10 μl of 3 mg of the target substance dissolved in 2 ml of chloroform was injected, and Mw was determined by polystyrene conversion.

<P3HA>
In each example or comparative example, PHBH: poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) was used as P3HA. This PHBH was obtained by culturing a PHBH-producing bacterium, and then collecting the resin component from the microbial cells. The HH ratio: the molar fraction (mol%) of 3-hydroxyhexanoate in PHBH was 5.8 mol. %, Mw is 556,000. As a PHBH-producing bacterium, Alcaligenes eutrophus AC32 (J. Bacteriol., 179, 4821 (1997)) in which a PHA synthase gene derived from Aeromonas caviae was introduced into Alcaligenes eutrophus was used.

<Modified nanocellulose>
In each Example, modified nanocellulose obtained by monoesterifying nanocellulose with succinic anhydride having a hexadecenyl group (alkenyl group having 16 carbon atoms) was used as the modified nanocellulose. The modified nanocellulose was produced by the production method disclosed in Japanese Patent No. 5496435.

Example 1
A dry blend of 0.5 parts by weight of behenamide (BA) and 0.5 parts by weight of erucamide (EA) with respect to 100 parts by weight of PHBH (hereinafter sometimes referred to as “powder mixture”). Got).

To 60 parts by weight of the powder mixture, 40 parts by weight of modified nanocellulose was added and mixed with a Henschel mixer to obtain a mixture. Since the mixture contains 30% cellulose, the mixture is hereinafter referred to as 30% powder master batch or 30% powder MB.
First, 66 parts by weight of the powder mixture and 33 parts by weight of 30% powder MB are mixed outside the extruder, then supplied to the extruder, pelletized, and then subjected to injection molding to form a strip of 10 mm × 80 mm × 4 mm in size. A test piece was obtained. Hereinafter, this is referred to as a once-kneaded test piece.

  Further, 30% powder MB was kneaded with an extruder to obtain pellets. Hereinafter, the pellet is referred to as 30% pellet MB. After mixing 66 parts by weight of the powder mixture and 33 parts by weight of 30% pellets MB outside the extruder, the mixture was fed to the extruder and pelletized, and then subjected to injection molding to form a strip of 10 mm × 80 mm × 4 mm in size. A specimen was obtained. Hereinafter, this is referred to as a twice-kneaded test piece.

  Furthermore, after 30% powder MB was kneaded with an extruder to obtain 30% pellet MB, the 30% pellet MB was again kneaded with an extruder to obtain 30% pellet MB (2). After 66 parts by weight of the powder mixture and 33 parts by weight of 30% pellets MB (2) were mixed outside the extruder, they were supplied to the extruder, pelletized, and then injection molded to give a size of 10 mm × 80 mm × 4 mm. A strip-shaped test piece was obtained. Hereinafter, this is referred to as a three-time test piece.

  Each test piece contains the modified nanocellulose in such an amount that the nanocellulose excluding the weight of the portion derived from the modifying agent (alkenyl group-containing succinic anhydride) accounts for 10% by weight with respect to the entire resin composition.

  In the above, a twin screw extruder (Technobel, φ15 mm, L / D45 twin screw) is used as the extruder, each cylinder temperature of the extruder is 150 ° C., the die head temperature is 160 ° C., and the screw rotation speed is Set to 200 rpm. NPX7 manufactured by Nissei Plastic Industry Co., Ltd. was used for injection molding, and the cylinder temperature was set to 140 to 150 ° C and the mold temperature was set to 17 ° C.

  In order to advance crystallization of PHBH in each test piece, after injection molding, each test piece was allowed to stand overnight in a dryer set at 70 ° C. for annealing. However, when annealing was not carried out, each test was carried out without being put in a dryer.

(Comparative Example 1)
After the powder mixture was supplied to an extruder and pelletized, injection molding was performed to obtain a strip-shaped test piece having a size of 10 mm × 80 mm × 4 mm. The manufacturing conditions are the same as in Example 1 except that the mold temperature during injection molding is changed to 35 ° C. The test piece does not contain a cellulosic material.

(Comparative Example 2)
Each test piece was obtained in the same manner as in Example 1 except that unmodified nanocellulose (Serisch KY100G, manufactured by Daicel Finechem Co., Ltd.) was used instead of the modified nanocellulose. However, the mold temperature during injection molding was changed to 35 ° C. Each test piece contains nanocellulose in an amount accounting for 10% by weight with respect to the entire resin composition.

(Comparative Example 3)
Each test piece was obtained in the same manner as in Example 1 except that unmodified bleached pulp was used instead of the modified nanocellulose. However, the mold temperature during injection molding was changed to 35 ° C. Each test piece contains bleached pulp in an amount occupying 10% by weight based on the entire resin composition.

(Optical microscope observation)
The test piece of Example 3 that was not annealed was heat-pressed at 150 ° C. and polarized light was observed under an optical microscope under crossed Nicols. The photographed micrograph is shown in FIG.

  From the photomicrograph of FIG. 1, it can be seen that fibrous modified nanocellulose is dispersed in the resin matrix.

(Bending test)
Using a universal testing machine (manufactured by Shimadzu Corporation, AG5000E type), a three-point bending test was performed at a speed of 10 mm / min and a distance between supporting points = 64 mm, and the bending elastic modulus and bending strength of each test piece were measured. The results are shown in Tables 1 and 2.

  From the above results, regardless of the number of times of kneading, each test piece of Example 1 to which modified nanocellulose was added was Comparative Example 1 to which cellulose-based material was not added, and Comparative Example 2 to which unmodified nanocellulose was added. It can be seen that the flexural modulus and the bending strength are greatly improved as compared with the test piece of Comparative Example 3 to which unmodified bleached pulp was added. From this, it was confirmed that the molded object which improved the intensity | strength is obtained by mix | blending modified | denatured nanocellulose with P3HA.

(Differential scanning calorimetry)
The crystallization peak temperature (Tch) was measured by raising the temperature of each test piece from 23 ° C. to 200 ° C. and then lowering it to 23 ° C. using DSC 6220 manufactured by Hitachi High-Tech Science Co., Ltd. In addition, the crystallinity is measured by Macromolecules, 28 (1995), pp. 4822-4828 (referred to as “reference”) crystallinity of P (3HB-co-5% 3HH) (described in Table 2, no2 of reference) and crystallization peak area (ΔHm, reference Based on the value of Table 3, no2), the crystallization peak area (ΔHm) of each test piece was multiplied by a coefficient of 0.609 (coefficient calculated from Non-Patent Document 1) and divided by the resin component content. It was calculated by the following formula 1. The results are shown in Table 3.
Crystallinity (%) = ΔHm x 0.609 / (resin component content)

  From the above results, in the test piece of Example 1, the crystallization temperature (Tch) is shifted to the high temperature side, P3HA is more easily crystallized, and the crystallinity is increased. It can be seen that the amount of crystals increases. All the results indicate that the molding processability of P3HA is improved by the addition of the modified nanocellulose.

(Examples 2 to 5 and Comparative Example 4)
<Preparation of pellet>
The powder mixture described above and 30% powder MB were mixed outside the extruder at a ratio such that the modified nanocellulose concentration relative to the entire resin composition was 0.25 wt%, 5.0 wt%, or 10 wt%. . Next, using a twin-screw extruder TEM26SS manufactured by Toshiba Machine Co., Ltd., each concentration mixture was melt-kneaded at a cylinder temperature of 120 to 140 ° C., and the molten resin was discharged from a strand of φ4 mm, 3 holes. It was crystallized and solidified by passing through a 1.5 m long hot tub filled with warm water, and was cut into pellets with a pelletizer. The last cut pellets were dried at 60 ° C. for a whole day and night and used for the solidification test.

<Solidification test>
The solidification test was performed as follows. Using a small kneader XPlor series MC5 manufactured by DSM, each pellet having different modified nanocellulose concentrations was melt-kneaded at a set temperature of 170 ° C., a screw rotation speed of 100 rpm, and a kneading time of 3 minutes, and then the molten resin was heated to about 55 ° C. It was put into a warm bath and the time required for the molten resin to solidify was measured. The faster the crystallization, the shorter the solidification time. In the solidification test, the smaller the number, the better the solidification characteristics. The excellent solidification characteristic means that the solidified product can be quickly solidified during the molding process, and the molded product can be produced with excellent productivity (that is, excellent in molding processability). The solidification time was measured three times in the same procedure, and the average value is shown in Table 4.

  In addition, the result obtained by using 30% powder MB as it is for the solidification test is the result of the modified nanocellulose concentration of 30%, and the powder mixture was used as it is for the solidification test, and the modified nanocellulose concentration was 0. % Results.

From the above results, it was confirmed that the blending of modified nanocellulose shortens the solidification time of P3HA and provides a resin composition having excellent moldability. The reason why such an effect was obtained is presumed that the modified nanocellulose acted as a crystal nucleating agent for P3HA.

Claims (8)

  An aliphatic polyester resin composition comprising poly (3-hydroxyalkanoate) and modified nanocellulose.   The aliphatic polyester resin composition according to claim 1, wherein the modified nanocellulose is a modified nanocellulose in which a hydroxyl group of cellulose is esterified.   The aliphatic polyester resin composition according to claim 1, wherein the modified nanocellulose is a modified nanocellulose in which a hydroxyl group of cellulose is esterified with a dicarboxylic acid.   The aliphatic polyester resin composition according to claim 1, wherein the modified nanocellulose is a modified nanocellulose in which a hydroxyl group of cellulose is esterified with succinic acid having an alkyl group or an alkenyl group. The poly (3-hydroxyalkanoate) has the formula: [—CHR—CH ₂ —CO—O—] (wherein R represents a linear or branched alkyl group having 1 to 15 carbon atoms). The aliphatic polyester resin composition of any one of Claims 1-4 containing the repeating unit shown.   Poly (3-hydroxyalkanoate) is poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate). Rate-co-3-hydroxyhexanoate), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate), and poly (3-hydroxybutyrate-co-4-hydroxybutyrate) The aliphatic polyester resin composition according to any one of claims 1 to 4, which is at least one selected from the group.   The aliphatic polyester resin composition according to any one of claims 1 to 6, wherein the content of the modified nanocellulose is 1 to 100 parts by weight with respect to 100 parts by weight of poly (3-hydroxyalkanoate). The molded object formed by shape | molding the aliphatic polyester resin composition of any one of Claims 1-7.