JP2009263414A - Thermoformable material excellent in biodegradability, method for producing the same, and thermoformed article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a thermoformable material excellent in biodegradability and thermoformability, and capable of molding a thermoformed article improved in elastic modulus; a method for producing the thermoformable material; and the thermoformed article. <P>SOLUTION: This thermoformable material consists of: a hydroxy group-containing substance of natural origin as a base material; and a mixture of a biodegradable thermoplastic polymer (component A) having an aliphatic polyester chain as a graft chain and powder (component B) of the natural substance, wherein the ratio of the component B is 5 to 900 pts.wt. based on 100 pts.wt. component A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermoforming material having excellent biodegradability, a method for producing the same, and a thermoformed article having excellent biodegradability.

Biodegradable thermoplastic polymers having a hydroxyl group derived from a natural substance as a base material and an aliphatic polyester chain as a graft chain are known (Patent Documents 1 and 2).
Such a thermoplastic polymer is excellent in biodegradability and thermoformability, but according to the study of the present inventors, the thermoform is unsatisfactory in terms of elastic modulus, for example, It was not yet satisfactory as an agricultural film, garbage bag, or food wrap film.

Japanese Patent Laid-Open No. 9-12588 JP-A-11-71401

  The present invention provides a thermoforming material that gives a thermoformed article having excellent biodegradability and thermoformability and improved elastic modulus, and also provides a method for producing the thermoformed material and a thermoformed article. Let that be the issue.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, according to the present invention, the following inventions are provided.
[1] A mixture of a biodegradable thermoplastic polymer (component A) having a hydroxyl group derived from a natural material as a base material and an aliphatic polyester chain as a graft chain, and a natural material powder (component B). The thermoforming material, wherein the proportion of component B is 5 to 900 parts by weight per 100 parts by weight of component A.
[2] The thermoforming material according to [1], wherein the natural substance powder (component B) is a natural polymer substance powder selected from cellulose powder, chitin powder, and wood powder.
[3] The thermoforming material according to [1] or [2], wherein the average particle size of the component B is 12 mesh size or less.
[4] A graft polymerization reaction step of forming a biodegradable thermoplastic polymer (component A) by subjecting a hydroxyl group-derived substance derived from a natural substance to a graft polymerization reaction with an aliphatic polyester chain-forming component in a dissolved state; The powder (component B) is mixed with a hot melt of component A, and the proportion of component B is 5 to 900 parts by weight per 100 parts by weight of component A Material manufacturing method.
[5] A film molded body formed by thermoforming the thermoforming material according to any one of [1] to [3].

According to the thermoforming material of the present invention, a molded product such as a film, a sheet, or a block can be easily obtained by thermoforming. And the molded product in this case is remarkably excellent in biodegradability. Furthermore, the thermoformed body obtained from the thermoforming material of the present invention has a feature of having a high elastic modulus.
The film molded body of the present invention is excellent in biodegradability and rich in elasticity, and is suitable as an agricultural film, a garbage bag, a food wrap film and the like. Moreover, since the film molded object of this invention is excellent in biodegradability, it can also be landfilled after the use.

Hereinafter, the thermoforming material of the present invention and the production method thereof will be described in detail.
The thermoforming material of the present invention comprises a mixture of a biodegradable thermoplastic polymer (component A) and a natural substance powder (component B), and the biodegradable thermoplastic polymer (component A). Is a graft polymer in which a hydroxyl group-derived substance derived from a natural substance (hereinafter also simply referred to as a natural substance) is used as a base material and an aliphatic polyester chain is graft-polymerized on the base material.

  In the present invention, a hydroxyl group-containing substance (natural substance) derived from a natural substance is used as a base material for obtaining a biodegradable thermoplastic polymer (graft polymer: component A). Such base materials include lignin-based substances (craft lignin, alcoholysis lignin, hydrolyzed lignin, lignosulfonate, etc.), sugar-based substances (monosaccharides, disaccharides, oligosaccharides, polysaccharides (cellulosic substances, starch) And polysaccharide substances such as chitin-based substances, chitosan-based substances and chitosan-based substances).

  In the present invention, an aliphatic polyester-forming material is used as a graft polymer chain material for a natural substance substrate. Examples thereof include cyclic lactones, oxycarboxylic acids, and mixtures of aliphatic dicarboxylic acids and aliphatic diols.

  Examples of the cyclic lactone include methyl ε-caprolactone, ε-caprolactone, β-propiolactone, β-butyrolactone, and δ-valerolactone.

  Examples of the oxycarboxylic acid include lactic acid, α-oxybutyric acid, glyceric acid, malic acid, tartaric acid, mandelic acid, tropic acid, glucosacric acid, and derivatives thereof.

Examples of the dicarboxylic acid component and the diol component that constitute the mixture of the aliphatic dicarboxylic acid and the diol include the following.
Dicarboxylic acid components include adipic acid, trimethyladipic acid, sebacic acid, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, 2,2-dimethylglutaric acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and the like can be used.
Examples of the diol component include ethylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

The biodegradable thermoplastic polymer (component A) used in the present invention is a graft polymerization reaction of a graft polymer chain material (aliphatic polyester chain material) to a hydroxyl group-derived substance (natural substance base material) derived from a natural substance. Can be obtained. In this case, the natural substance substrate is kept in a dissolved state and reacted with the graft polymer chain material. In order to keep the natural substance base in a dissolved state, a method of solubilizing the natural substance base in the graft polymer chain material, or an organic solvent that dissolves the natural substance base, for example, N-methylpyrrolidone, acetone, dioxane And so on.
The natural substance base can be reacted with a graft polymer chain material such as a cyclic lactone in the presence of a polyhydric alcohol.

  The graft polymerization reaction is performed at a polymerization temperature of room temperature to 180 ° C, preferably 30 to 170 ° C. The reaction time is 1 to 24 hours, preferably 2 to 20 hours. When the natural substance base material is dissolved in the organic solvent, the amount of the organic solvent used is 100 to 1000 parts by weight, preferably 200 to 500 parts by weight, per 100 parts by weight of the natural substance base material.

By the graft polymerization reaction, a graft polymer represented by the following general formula (I) is obtained.

  In the general formula (I), Z represents a hydroxyl group-containing substance residue (natural substance residue) derived from natural substances such as saccharides and lignin, R represents an alkylene group, and n represents a hydroxyl group contained in the natural substance. P represents the number of hydroxyl groups to be esterified in the hydroxyl group-containing material, which is 1 or more and less than n, and q is 1 or more, preferably 3 or more. The upper limit of q is about 100. In addition, np is the number of hydroxyl groups in the hydroxyl group-containing residue remaining without being esterified, and represents a number in the range of 0 to (n-1).

  The substitution rate p / n of the hydroxyl group contained in the natural substance substrate is 1/100 to 100/100, preferably 5/100 to 100/100. The product of p and q indicates the number of polyester chain forming components (lactone, oxycarboxylic acid or dicarboxylic acid) added to the hydroxyl group in the natural substance.

  When Z is derived from a saccharide, examples of the saccharide include monosaccharides such as glucose, fructose, mannose, arabinose, xylose and galactose, disaccharides such as sucrose, cellobiose and maltose, and cellotriose. Oligosaccharide, cellulose powder, starch, glycogen, caroten, laminaran, dextran, inulin, levan, mannan, xylan, pectic acid, alginic acid, chitin powder, guaran, heparin, chondroitin sulfate, hyaluronic acid, meskit gum, gatch gum, gum arabic, Examples include polysaccharides such as plant mucilage and bacterial polysaccharides. Moreover, you may utilize the molasses which are these mixtures. Molasses is obtained from sugarcane, sugar beet, etc., and may be refined molasses, ice molasses, or waste molasses obtained after sugar production, but it is advantageous from the economical point of view. is there.

  In the present invention, when a biodegradable thermoplastic polymer (component A) is produced, 1 to 100 graft chain forming components (lactone, oxycarboxylic acid or dicarboxylic acid) are added per mole of hydroxyl group contained in the natural substance. The molar ratio is preferably 4 to 70 mol. Examples of the polyester forming catalyst used in the present invention include conventional catalysts such as (eg, metal alcoholates such as tin, lead, manganese, and aluminum, catalysts such as metal carboxylates, alkyl metals, and chelate metals, and more specifically, For example, di-n-butyltin dilaurate, di (2-ethylhexanoate) tin, titanium tetraisopropoxide, aluminum triisopropoxide) and the like are used.

  The aforementioned graft polymer is described in detail in Patent Documents 1 and 2.

In the thermoforming material of the present invention, as the component B, powders of various natural substances are used. Examples of preferable component B include, for example, powders of natural polymer substances such as cellulose powder, chitin powder, and wood powder, and powders of natural inorganic substances such as silica, zeolite, calcium carbonate, and aluminum hydroxide. Two or more kinds of these solid powders can be mixed and used.
However, when the landfill treatment is performed after use, the whole is biodegraded in the soil, so that natural polymer substances such as cellulose powder, chitin powder, and wood powder are preferable from the viewpoint of reducing the burden on the environment.

  In the present invention, component A and component B are mixed. In this case, a method of mixing the component B into the heated melt of the component A can be preferably used. In this case, the mixing ratio of component B is 5 to 900 parts by weight, preferably 10 to 800 parts by weight, and more preferably 15 to 80 parts by weight per 100 parts by weight of component A. When mixing component A and component B, if the proportion of component B is too small, the elastic modulus of the resulting thermoformed article will not be satisfactory. On the other hand, if the proportion of component B is too large, a uniform mixture cannot be obtained, and the thermoforming of the resulting thermoforming material becomes poor, which is not preferable.

  When mixing component B with component A, component A is preferably heated to 50 to 250 ° C., more preferably 60 to 180 ° C., and melted. When heating at less than 50 ° C., component A may not melt. On the other hand, when heated above 250 ° C., thermal decomposition may occur.

  The particle size of component B is preferably 12 mesh size (L = 1.399 mm) or less, more preferably 60 mesh size (L = 0.246 mm) or less, from the viewpoint of improving the elastic modulus of the obtained molded body. More preferably, the size is 250 mesh size (L = 0.061 mm) or less. The lower limit particle size is not particularly limited, but is generally about 400 mesh size (L = 0.033 mm) from the viewpoint of availability. The mesh size is a Tyler mesh size.

  When using wood flour as component B, it can be used regardless of the type. For example, those obtained from conifers such as pine, cedar, and oak, and broad-leaved trees such as lauan, capol, chestnut, and poplar can be used.

  When cellulose powder is used as Component B, easily available high-purity cellulose powder can be used, or cellulose powder containing impurities such as wood can be used. Specific examples include cotton lint, cotton linter, and refined pulp. Further, squirt cellulose powder, bacterial cellulose powder or regenerated cellulose powder may be used.

  When chitin powder is used as component B, those obtained from crab or shrimp shells are readily available, but are not limited thereto, and may be obtained from insects, squids, shellfish, mushrooms and the like.

  The thermoforming material of the present invention comprises a graft polymer (component A) having a hydroxyl group derived from a natural product as a graft polymer substrate and an aliphatic polyester chain as a graft polymer chain, and a natural substance powder (component B). The component A is excellent in biodegradability, and therefore has excellent biodegradability as a whole. The thermoforming material of the present invention has thermoformability because the thermoformable graft polymer (component A) is obtained by dispersing the powdery component B in the matrix phase (continuous phase). Also, the thermoformability is excellent. Furthermore, the thermoforming material of the present invention has a structure in which a natural substance powder is dispersed in a graft polymer, and thus has a high elastic modulus and excellent mechanical strength. For example, when comparing a thermoformed article comprising only component A and a thermoformed article comprising component A and component B, the thermoformed article of the present invention comprising component A and component B has its tensile elastic modulus ( JIS K7113) is about twice, and its compressive strength (JISK7113) is 2.3 times or more, which is very excellent.

  The thermoforming material of the present invention is excellent in thermoformability. In this case, the thermoforming method includes hot pressing, extrusion molding, injection molding, foam molding and the like. In addition, the thermoformed product obtained from the thermoformed material of the present invention includes a film, a sheet, a plate, a pellet, various blocks of various containers, and the like.

The thermoforming temperature of the thermoforming material of the present invention is 50 to 250 ° C, preferably 60 to 180 ° C.

  Since the thermoforming material of the present invention is a thermodegradable biodegradable material, it can be used as an agricultural film or a food wrapping film, and can be landfilled after use. Particularly, those having excellent light transmittance can be suitably used as agricultural films, garbage bags, and food wrapping films that can be easily discarded.

  Next, the present invention will be described in detail by examples. In addition, all the parts and% shown in others are on the basis of weight.

Examples 1-3
Hydrolyzed lignin (HL1) obtained as a residue of the wood saccharification process was dehydrated by azeotropy with benzene. Next, 1 part by weight of the dehydrated hydrolyzed lignin (HL1) and 100 times mol (79.9 parts by weight) of caprolactone monomer in the hydrolyzed lignin (HL1) are mixed with a catalytic amount of dilauric acid. Graft polymerization was performed at 170 ° C. for 5 hours in the presence of dibutyltin to obtain an HL polycaprolactone derivative (HL1-PCL: Component A).

Next, using 80 parts by weight of HL1-PCL heated and melted at 60 ° C., 20 parts by weight of cellulose powder a (250 mesh size (fiber length L = 0.061 mm or less)) as a natural substance powder (component B) is used. A thermoforming material was prepared (Example 1). A thermoforming material was prepared using 20 parts by weight of chitin powder a (60 mesh size (L = 0.246 mm or less)) as natural substance powder (component B) (Example 2), and natural substance powder (component B). ) Was used to prepare a thermoforming material using 20 parts by weight of wood flour a (60 mesh size (L = 0.246 mm) or less) (Example 3). The thermoforming material obtained in Examples 1 to 3 was molded into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) with a hot press (heating temperature: 120 ° C.).
The mesh size is a Tyler mesh size (hereinafter the same in the examples).

Comparative Example 1
The HL polycaprolactone derivative (HL1-PCL) obtained in the same manner as in Example 1 was molded into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) by hot pressing (heating temperature: 120 ° C.). did.

  About the sheet | seat obtained in Examples 1-3 and the comparative example 1, the tension test was done based on JISK7113 (plastic tensile test method), and the tensile strength ((sigma)) and the tensile elasticity modulus (E) were measured. Further, thermogravimetric analysis (temperature increase rate: 10 ° C./min) was performed in a nitrogen stream to determine the pyrolysis temperatures (low temperature side Td1 and high temperature side Td2). Table 1 shows the results.

Example 4
Hydrolyzed lignin (HL2) obtained as a residue of a wood saccharification step different from that in Example 1 was dehydrated by azeotropy with benzene. Next, 1 part by weight of the dehydrated hydrolyzed lignin (HL2) and 100 times mole (79.9 parts by weight) of caprolactone monomer in the hydrolyzed lignin (HL2) are combined with a catalytic amount of dilauric acid. Polymerization was carried out at 170 ° C. for 5 hours in the presence of dibutyltin to obtain an HL polycaprolactone derivative (HL2-PCL: Component A).

  Next, 20 parts by weight of cellulose powder a (250 mesh size (fiber length L = 0.061 mm or less)) as a natural substance powder (component B) is mixed with 80 parts by weight of HL2-PCL heated and melted at 60 ° C. A thermoforming material was prepared. The obtained thermoplastic polymer was molded into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) with a hot press (heating temperature: 120 ° C.).

Comparative Example 2
The HL polycaprolactone derivative (HL2-PCL) obtained in the same manner as in Example 4 was molded into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) by hot pressing (heating temperature: 120 ° C.). did.

  About the sheet | seat obtained in Example 4 and the comparative example 2, the tensile test was done based on JISK7113 (plastic tensile test method), and the tensile strength ((sigma)) and the tensile elasticity modulus (E) were measured. Further, thermogravimetric analysis (temperature increase rate: 10 ° C./min) was performed in a nitrogen stream to determine the pyrolysis temperatures (low temperature side Td1 and high temperature side Td2). Table 2 shows the results.

Example 5
Waste molasses (ML) was dehydrated by azeotropy with benzene. Next, 1 part by weight of the dehydrated molasses (ML) and 100 times mol (131 parts by weight) of caprolactone monomer in the amount of hydroxyl groups in the molasses (ML) are present in a catalytic amount of dibutyltin dilaurate. Below, it superposed | polymerized at 170 degreeC for 5 hours, and obtained ML polycaprolactone derivative (ML-PCL: component A).

  Next, 80 parts by weight of ML-PCL heated and melted at 60 ° C. is mixed with 20 parts by weight of wood flour (60 mesh size (L = 0.246 mm or less)) as a mixture (component B) to obtain a thermoforming material. Prepared. The obtained thermoforming material was formed into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) with a hot press (heating temperature: 120 ° C.).

Comparative Example 3
ML polycaprolactone derivative (ML-PCL) obtained in the same manner as in Example 5 was molded into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) by hot pressing (heating temperature: 120 ° C.). did.

  The sheets obtained in Example 5 and Comparative Example 3 were subjected to a tensile test according to JIS K7113 (plastic tensile test method), and the tensile strength (μm) and the tensile modulus (E) were measured. Further, thermogravimetric analysis (temperature increase rate: 10 ° C./min) was performed in a nitrogen stream to determine the pyrolysis temperatures (low temperature side Td1 and high temperature side Td2). Table 3 shows the results.

Examples 6-16
Sucrose (S) was dehydrated by azeotropy with benzene. Next, 1 part by weight of the dehydrated sucrose (S) and 100 times mole (267 parts by weight) of caprolactone monomer in the amount of hydroxyl groups in the sucrose (S) were added in the presence of a catalytic amount of dibutyltin dilaurate. Polymerization was carried out at 5 ° C. for 5 hours to obtain an S-polycaprolactone derivative (S-PCL: Component A).

  Next, the S-PCL heated and melted at 60 ° C. was mixed with the natural substance powder (component B) shown in Table 4 in the formulation shown in Table 4 to prepare a thermoforming material. The obtained thermoforming material was molded into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) with a hot press (heating temperature: 120 ° C.). In addition, the natural substance powders (cellulose a, chitin a, wood powder a) shown in Table 4 are the same as in Examples 1 to 3. Aluminum hydroxide has a size of 270 mesh (L = 0.053 mm) or less.

Comparative Example 4
S-PCL obtained in the same manner as in Examples 6 to 14 was formed into a sheet (thickness: 1.0 mm, length: 100 mm, width: 100 mm) with a hot press (heating temperature: 120 ° C.).

  The sheets obtained in Examples 6 to 16 and Comparative Example 4 were subjected to a tensile test according to JIS K7113 (plastic tensile test method), and the tensile strength (σ) and the tensile modulus (E) were measured. Further, thermogravimetric analysis (temperature increase rate: 10 ° C./min) was performed in a nitrogen stream to determine the pyrolysis temperatures (low temperature side Td1 and high temperature side Td2). Table 4 shows the results.

Claims (5)

  A mixture of a biodegradable thermoplastic polymer (component A) having a hydroxyl group derived from a natural material as a base material and an aliphatic polyester chain as a graft chain, and a powder of the natural material (component B). A thermoforming material, wherein the proportion of B is 5 to 900 parts by weight per 100 parts by weight of component A.   2. The thermoforming material according to claim 1, wherein the natural substance powder (component B) is a natural polymer substance powder selected from cellulose powder, chitin powder, and wood powder.   The thermoforming material according to claim 1 or 2, wherein the average particle size of the component B is 12 mesh size or less.   In a dissolved state, a hydroxyl group-derived substance derived from a natural substance is subjected to a graft polymerization reaction with an aliphatic polyester chain forming component to form a biodegradable thermoplastic polymer (component A), and a natural substance powder ( Production of thermoforming material characterized in that it comprises a mixing step in which component B) is mixed with the hot melt of component A, and the proportion of component B is 5 to 900 parts by weight per 100 parts by weight of component A Method.   The film molded object made by thermoforming the thermoforming material in any one of Claims 1-3.