JP2022145493A - Biodegradable resin composition, biodegradable resin molding, and method for producing biodegradable resin composition - Google Patents

Abstract

To provide a composition of a biodegradable resin and a molding of the same, the biodegradable resin including an aliphatic polyester resin, an aliphatic-aromatic polyester resin, an aliphatic oxycarboxylic acid-based resin, and the like, which has an improved biodegradation rate and degradation ratio in a home compost and ocean.SOLUTION: Provided is a biodegradable resin composition comprising a biodegradable resin and galactomannan, where the biodegradable resin is a polyester resin comprising, as main constitutional components, a constitutional unit derived from a diol and a constitutional unit derived from a dicarboxylic acid. The biodegradable resin composition contains galactomannan in an amount of more than 0.1 pts.mass and 30 pts.mass or less relative to 100 pts.mass of the biodegradable resin.SELECTED DRAWING: None

Description

The present invention relates to a biodegradable resin composition and a biodegradable resin molding. More specifically, a biodegradable resin composition containing a biodegradable resin such as an aliphatic polyester, an aliphatic-aromatic polyester, or polylactic acid, and extrusion molding or injection molding of this biodegradable resin composition It relates to a biodegradable resin molding.

In recent years, concerns about ecological and environmental pollution due to marine disposal of plastic products have become apparent. In countries around the world, various regulations are being enacted from the viewpoint of environmental pollution prevention. For example, in Europe, regulations and laws are being enacted banning the use of single-use plastic shopping bags and single-use plastic container cups and plates in retail. In order to be exempt from the use prohibition measures of this law, it is necessary to use biomass that contains more than the minimum biomass content stipulated here as a raw material and that can be composted at home (home compostable products) ). Recently, there is a growing demand for marine biodegradable plastic products that can be decomposed even in the sea.

Conventionally, biodegradable plastics (biodegradable resins) include polybutylene terephthalate/adipate (hereinafter abbreviated as PBAT), polylactic acid (hereinafter abbreviated as PLA), and polybutylene succinate (hereinafter abbreviated as PLA). PBS), polybutylene succinate/adipate (hereinafter abbreviated as PBSA), polyhydroxyalkanoate (hereinafter abbreviated as PHA), and the like are known. Furthermore, PHA includes poly(3-hydroxybutyrate) (hereinafter abbreviated as PHB), poly(3-hydroxybutyrate/3-hydroxyvalerate) (hereinafter abbreviated as PHBV), poly(3-hydroxy butyrate/3-hydroxyhexanoate) (hereinafter abbreviated as PHBH), poly(3-hydroxybutyrate/4-hydroxybutyrate), and the like.

These resins not only have different biodegradation speeds and decomposition rates, but also have different mechanical properties such as tensile elongation at break and flexural modulus. These resins are combined or mixed with other secondary materials and additives to improve physical properties such as mechanical strength.

Patent Document 1 discloses a resin composition containing a biodegradable resin and a mannan degradation product, specifically polylactic acid and galactomannooligosaccharide.
Patent Document 2 discloses a resin composition containing polylactic acid, a mannan decomposition product, and an aliphatic polyester containing glycol and an aliphatic dicarboxylic acid or its anhydride as main components.
Patent Document 3 discloses a resin composition containing an aliphatic polyester, starch, and a water-soluble polymer, and exemplifies guar gum, which is a kind of galactomannan, as the water-soluble polymer.

WO01/042367 JP-A-2004-91681 JP 2018-53165 A

For home compostable plastic products and marine biodegradable plastic products, the biodegradation rate or rate is more biodegradable than under conventional conditions where they are generally considered biodegradable. Faster biodegradation rate than conventional biodegradable resins such as PBAT, PBS, PBSA, PLA, and PHBH under difficult environment (for example, environment with low temperature and few degrading bacteria), and more biodegradation in the same time is required.

Although it has been shown that the resin composition described in Patent Document 1 above is biodegraded to some extent in activated sludge and soil, it took several months to decompose, and the rate of decomposition was not sufficient. Moreover, the biodegradable resin actually used is polylactic acid, which is known to hardly decompose in seawater, and its marine biodegradability is also insufficient.

It has been shown that the resin composition described in Patent Document 2 is decomposed by a specific enzyme. It was not rapidly decomposed in water or in seawater).

The resin composition described in Patent Document 3 is a composition containing a water-soluble polymer for the purpose of increasing the affinity between an aliphatic polyester resin and starch and uniformly dispersing it, and is biodegradable and No attention has been paid to its promoting effect. In addition, for that purpose, it is characterized by blending the water-soluble polymer as an aqueous solution and performing melt-kneading, which requires special equipment and a drying process. There has been a problem such as deterioration of physical properties due to hydrolysis of the resin due to moisture sometimes contained.

The present invention has been made in view of this background, and the biodegradation speed and decomposition rate in home compost and the sea required for home compostable plastic products and marine biodegradable plastic products that are required in recent years An object of the present invention is to provide a resin composition containing a biodegradable resin such as an aliphatic polyester-based resin, an aliphatic-aromatic polyester-based resin, an aliphatic oxycarboxylic acid-based resin, etc., and a molded product thereof.

As a result of extensive studies to solve the above problems, the present inventors found that by adding a specific amount of galactomannan, which is a type of polysaccharide, to a biodegradable resin, the biodegradation rate of conventional biodegradable resins In particular, it was found that the acceleration of the biodegradation rate is remarkable in environments such as home compost and the sea, leading to the present invention.

That is, the gist of the present invention resides in the following [1] to [7].
[1] A biodegradable resin composition containing a biodegradable resin and a galactomannan, wherein the biodegradable resin contains a structural unit derived from a diol and a structural unit derived from a dicarboxylic acid as main structural components Polyester A biodegradable resin composition containing more than 0.1 parts by mass and 30 parts by mass or less of galactomannan with respect to 100 parts by mass of the biodegradable resin.
[2] The biodegradable resin composition according to [1], wherein the galactomannan is one or more selected from the group consisting of fenugreek gum, guar gum, tara gum, locust bean gum and cassia gum.
[3] The biodegradable resin composition according to [1] or [2], wherein the diol is an aliphatic diol and the dicarboxylic acid is an aliphatic dicarboxylic acid and/or an aromatic dicarboxylic acid. [4] The biodegradability according to any one of [1] to [3], wherein the biodegradable resin is an aliphatic polyester resin (A) and/or an aliphatic-aromatic polyester resin (B). Resin composition.
[5] A biodegradable resin molded article that is an extruded or injection molded article of the biodegradable resin composition according to any one of [1] to [4].
[6] A biodegradable resin composition containing a biodegradable resin and a galactomannan, wherein the biodegradable resin is an aliphatic oxycarboxylic acid-based resin, based on 100 parts by mass of the biodegradable resin and a biodegradable resin composition containing more than 0.1 parts by mass and 6.6 parts by mass or less of galactomannan. [7] A method for producing a biodegradable resin composition, comprising the step of melt-kneading a biodegradable resin and galactomannan powder.

INDUSTRIAL APPLICABILITY According to the present invention, a biodegradable resin molded article having excellent biodegradability even in home compost and the sea, and a biodegradable resin composition capable of molding the molded article are provided.

Embodiments of the present invention will be described in detail below.
The present invention is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention. In this specification, when a numerical value or a physical property value is sandwiched before and after the "~", it is used to include the values before and after it.

[Galactomannan]
A biodegradable resin composition, which is one embodiment of the present invention, is characterized by containing a certain amount of galactomannan relative to the biodegradable resin. Galactomannan is a polysaccharide composed of mannose and galactose, and galactose (α-D-galactose Pyranose) has a structure of α1-6 linkage.

Although the mechanism by which galactomannan promotes biodegradation is not sufficiently clear, it is considered as follows.
Many microorganisms such as bacteria and fungi that decompose vegetable waste and dead land plants live in home compost and soil. Galactomannan is a polysaccharide contained in terrestrial plants such as leguminous plants, and a large number of microorganisms that decompose it for nutrition live there. Unlike cellulose, galactomannan is amorphous and has a high affinity for water, so it is easily decomposed by microorganisms. Therefore, when the biodegradable resin composition of the present embodiment is left in home compost or soil, the galactomannan portion is rapidly decomposed first, and the biodegradable resin becomes susceptible to decomposition due to the increase in surface area. In addition, it is thought that microorganisms that decompose the biodegradable resin using the decomposition product of galactomannan as a nutrient source proliferate, and the decomposition is promoted.
Although the ocean is an environment with fewer microorganisms and nutrients than land, microorganisms that decompose seaweed are widely distributed. Main polysaccharides constituting seaweed include alginic acid contained in brown algae and agarose and carrageenan contained in red algae. Among these, alginic acid has mannuronic acid, which is an oxide of mannose, as a basic skeleton, and agarose and carrageenan have galactose as a basic skeleton, so there are many microorganisms in the ocean that use mannose and galactose as their nutrient sources. . Since the galactomannan contained in the biodegradable resin composition of the present invention is composed of mannose and galactose, it is rapidly degraded by these microorganisms even in the sea. Therefore, as in the case of home compost and soil, it is thought to have the effect of increasing the surface area, increasing the number of microorganisms, and promoting decomposition.

Galactomannans are abundant in some plants and fungi, and polysaccharide thickeners are obtained from the seeds of leguminous plants in particular. Examples of such galactomannans include fenugreek gum, guar gum, tara gum, locust bean gum, cassia gum and the like, preferably guar gum and locust bean gum.

A plant-derived galactomannan can be obtained by selecting plant seeds or the like as a raw material, and performing processes such as extraction, filtration, purification, drying, and pulverization. In addition, depending on the application of the biodegradable resin composition and its molded product, the extraction and purification steps may be omitted, and a part of the plant containing a large amount of galactomannan may be dried and pulverized and used as it is.

In the biodegradable resin composition, the molecular weight of the galactomannan is not particularly limited, but the weight average molecular weight (Mw) is preferably 20000 or more, more preferably 30000 or more, and even more preferably 50000 or more. is. When the molecular weight is in the above range, it is difficult to dissolve in cold water or hot water, suppresses the occurrence of problems such as stickiness when the molded article gets wet, and can suppress deterioration of the contents when used as a container. . On the other hand, it is preferably 400,000 or less, more preferably 350,000 or less, even more preferably 300,000 or less. When the molecular weight is within the above range, galactomannan can be easily extracted and purified, and can be produced efficiently. The average molecular weight of galactomannan can be measured by size exclusion chromatography (SEC). For example, from the chromatogram obtained by measuring an aqueous solution of galactomannan with HPLC equipped with a commercially available aqueous SEC column (eg, Shodex OHpak SB-804 HQ (Showa Denko)), a pullulan standard with a known molecular weight It can be obtained as a relative molecular weight.

The biodegradable resin composition may be a polyester in which the biodegradable resin contains structural units derived from a diol and structural units derived from a dicarboxylic acid, which will be described later, as main structural components. In that case, it is preferable to contain more than 0.1 parts by mass and 30 parts by mass or less of galactomannan with respect to 100 parts by mass of the biodegradable resin. Within the above range, the effect of promoting biodegradation by the galactomannan can be sufficiently obtained, and the strength and aesthetic appearance of the resulting molded product are also sufficient. Also, it is preferably 0.4 parts by mass or more and 20 parts by mass or less, and more preferably 0.8 parts by mass or more and 15 parts by mass or less.

In the biodegradable resin composition, the biodegradable resin may be an aliphatic oxycarboxylic acid resin described later. In that case, it is preferable to contain more than 0.1 parts by mass and 6.6 parts by mass or less of galactomannan with respect to 100 parts by mass of the biodegradable resin. By setting it as the said range, the effect of biodegradation acceleration|stimulation by galactomannan can fully be acquired, and it is preferable. Specifically, it is more preferably 0.4 parts by mass or more and 6.3 parts by mass or less, and still more preferably 0.8 parts by mass or more and 5 parts by mass or less.
In addition, only 1 type of galactomannan may be contained in the biodegradable resin composition, and 2 or more types may be contained. Moreover, a commercially available galactomannan can be used for the biodegradable resin composition.

[Biodegradable resin]
The biodegradable resin contained in the biodegradable resin composition is a biodegradable plastic, and conventionally known biodegradable plastics can be used.
The biodegradable resin may be a polyester containing structural units derived from a diol and a structural unit derived from a dicarboxylic acid as main structural components, or may be an aliphatic oxycarboxylic acid-based resin. The "main structural unit" is usually a structural unit whose structural unit is contained in the polyester resin in an amount of 80% by mass or more, and may be 90% by mass or more, and a structural unit other than the main structural unit is It may be not contained at all, ie 100% by weight.

The polyester containing structural units derived from diols and structural units derived from dicarboxylic acid as main constituents is not particularly limited, but aliphatic polyester resin (A), aliphatic - aromatic polyester resin (B) is mentioned.
Two or more of the aliphatic polyester resin (A) and the aliphatic-aromatic polyester resin (B) may be mixed and used.

Each biodegradable resin is described below.
Incidentally, the aliphatic polyester resin (A) and the aliphatic - aromatic polyester resin (B) are polymers each having repeating units, but each repeating unit is a compound derived from each repeating unit. Also called a compound unit for For example, a repeating unit derived from an aliphatic diol is an "aliphatic diol unit", a repeating unit derived from an aliphatic dicarboxylic acid is an "aliphatic dicarboxylic acid unit", and a repeating unit derived from an aromatic dicarboxylic acid is an "aromatic dicarboxylic acid unit". Also called "acid unit".

<Aliphatic polyester resin (A)>
As the aliphatic polyester-based resin (A), an aliphatic polyester-based resin containing an aliphatic diol unit and an aliphatic dicarboxylic acid unit as main structural units is preferable.

The aliphatic polyester-based resin (A) preferably has succinic acid units, and more preferably the proportion of succinic acid units in all dicarboxylic acid units is 5 mol % or more and 100 mol % or less. The aliphatic polyester-based resin (A) may be a mixture of aliphatic polyester-based resins having different amounts of succinic acid units. containing only succinic acid units as) and an aliphatic polyester resin containing an aliphatic dicarboxylic acid unit other than succinic acid are blended, and the succinic acid unit amount in the aliphatic polyester resin (A) can be adjusted within the above preferred range.

More specifically, the aliphatic polyester resin (A) is a polyester resin containing an aliphatic diol unit represented by the following formula (1) and an aliphatic dicarboxylic acid unit represented by the following formula (2) is.
-OR ¹ -O- (1)
-OC-R ² -CO- (2)

In formula (1), R ¹ represents a divalent aliphatic hydrocarbon group. In formula (2) above, R ² represents a divalent aliphatic hydrocarbon group. The aliphatic diol units and aliphatic dicarboxylic acid units represented by the above formulas (1) and (2) may be derived from compounds derived from petroleum or from compounds derived from plant materials. No, but preferably derived from compounds derived from plant sources.

When the aliphatic polyester resin (A) is a copolymer, even if two or more aliphatic diol units represented by formula (1) are contained in the aliphatic polyester resin (A) Well, the aliphatic polyester resin (A) may contain two or more kinds of aliphatic dicarboxylic acid units represented by the formula (2).

As described above, the aliphatic dicarboxylic acid units represented by formula (2) preferably contain 5 mol % or more and 100 mol % or less of succinic acid units relative to all dicarboxylic acid units. By setting the amount of succinic acid constitutional units in the aliphatic polyester resin (A) within the predetermined range, it is possible to obtain a biodegradable resin composition with improved moldability and excellent heat resistance and degradability. becomes. For the same reason, the amount of succinic acid units in the aliphatic polyester resin (A) is preferably 10 mol% or more, more preferably 50 mol% or more, and still more preferably 64 mol% or more with respect to all dicarboxylic acid units. , particularly preferably 68 mol % or more.
Hereinafter, the ratio of succinic acid units to all dicarboxylic acid units in the aliphatic polyester resin (A) may be referred to as "amount of succinic acid units".

In addition, the aliphatic dicarboxylic acid unit represented by formula (2) contains 5 mol% or more and 50 mol% or less of one or more kinds of aliphatic dicarboxylic acid units in addition to succinic acid with respect to the total dicarboxylic acid units. more preferably. By copolymerizing aliphatic dicarboxylic acid units other than succinic acid within the predetermined range, the degree of crystallinity of the aliphatic polyester resin (A) can be lowered, and the biodegradation rate can be increased. For the same reason, the amount of aliphatic dicarboxylic acid units other than succinic acid in the aliphatic polyester resin (A) is preferably 10 mol% or more and 45 mol% or less with respect to all dicarboxylic acid units, more preferably It is 15 mol % or more and 40 mol % or less.

The aliphatic diol that gives the diol unit represented by formula (1) is not particularly limited, but from the viewpoint of moldability and mechanical strength, aliphatic diols having 2 to 10 carbon atoms are preferable, and 4 or more carbon atoms. Aliphatic diols of 6 or less are particularly preferred. Examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, etc. Among them, 1,4-butanediol is particularly preferred. Two or more kinds of the aliphatic diols may be used.

The aliphatic dicarboxylic acid component that provides the aliphatic dicarboxylic acid unit represented by formula (2) is not particularly limited, but aliphatic dicarboxylic acids having 2 to 40 carbon atoms and derivatives thereof such as alkyl esters are preferable. Aliphatic dicarboxylic acids having 4 to 10 carbon atoms and their derivatives such as alkyl esters are particularly preferred. Examples of aliphatic dicarboxylic acids having 2 to 40 carbon atoms other than succinic acid and derivatives such as alkyl esters thereof include adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, and alkyl esters thereof. Among them, adipic acid and sebacic acid are preferred, and adipic acid is particularly preferred. Two or more types of the aliphatic dicarboxylic acid components may be used, and in this case, a combination of succinic acid and adipic acid is preferred.

The aliphatic polyester-based resin (A) may have a repeating unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of aliphatic oxycarboxylic acid components that give aliphatic oxycarboxylic acid units include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy -3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, 6-hydroxycaproic acid, etc., or derivatives such as lower alkyl esters or intramolecular esters thereof. When optical isomers exist in these compounds, they may be D-, L-, or racemic, and may be solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid or derivatives thereof are particularly preferred. These aliphatic oxycarboxylic acids may be used alone or as a mixture of two or more.

When the aliphatic polyester-based resin (A) contains these aliphatic oxycarboxylic acid units, the content thereof is, from the viewpoint of moldability, 100 mol% of all structural units constituting the aliphatic polyester-based resin (A). is preferably 20 mol % or less, more preferably 10 mol % or less, still more preferably 5 mol % or less, and most preferably 0 mol % (not included).

In addition, the aliphatic polyester resin (A) is a trifunctional or higher aliphatic polyhydric alcohol, a trifunctional or higher aliphatic polycarboxylic acid or its acid anhydride, or a trifunctional or higher aliphatic polyoxycarboxylic acid component. The melt viscosity may be increased by copolymerizing the.

Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane and glycerin, and specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol. These may be used alone or in combination of two or more.
Specific examples of trifunctional aliphatic polycarboxylic acids or acid anhydrides thereof include propanetricarboxylic acid or acid anhydrides thereof, and specific examples of tetrafunctional polycarboxylic acids or acid anhydrides thereof include: cyclopentanetetracarboxylic acid or its acid anhydride, and the like. These may be used alone or in combination of two or more.

In addition, the trifunctional aliphatic oxycarboxylic acid includes (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Any type can be used, but from the viewpoint of moldability, mechanical strength and molded product appearance, (i) two carboxyl groups and one hydroxyl group such as malic acid are combined in the same molecule. A type having such an acid is preferable, and more specifically, malic acid is preferably used. In addition, the tetrafunctional aliphatic oxycarboxylic acid component has (i) a type in which three carboxyl groups and one hydroxyl group are shared in the same molecule, (ii) two carboxyl groups and two hydroxyl groups. and (iii) a type in which three hydroxyl groups and one carboxyl group are shared in the same molecule. Those having more than one are preferable, and more specific examples include citric acid, tartaric acid, and the like. These may be used alone or in combination of two or more.

When the aliphatic polyester resin (A) contains such structural units derived from trifunctional or higher functional components, the content thereof is 100 mol% of the total structural units constituting the aliphatic polyester resin (A), The lower limit is usually 0 mol % or more, preferably 0.01 mol % or more, and the upper limit is usually 5 mol % or less, preferably 2.5 mol % or less.

As the method for producing the aliphatic polyester-based resin (A), a known method for producing polyester can be employed. Moreover, the polycondensation reaction at this time is not particularly limited, as it is possible to set appropriate conditions that have been conventionally employed. In general, a method is adopted in which the degree of polymerization is further increased by carrying out an operation under reduced pressure after allowing the esterification reaction to proceed.

When the diol component forming the diol unit and the dicarboxylic acid component forming the dicarboxylic acid unit are reacted during the production of the aliphatic polyester resin (A), the produced aliphatic polyester resin (A) is the target The usage amounts of the diol component and the dicarboxylic acid component are set so as to have a composition of Usually, the diol component and the dicarboxylic acid component are reacted in substantially equimolar amounts, but since the diol component distills out during the esterification reaction, it is usually 1 to 20 mol % in excess of the dicarboxylic acid component. Used.

When the aliphatic polyester resin (A) contains components (optional components) other than essential components such as aliphatic oxycarboxylic acid units and polyfunctional component units, the aliphatic oxycarboxylic acid units and polyfunctional component units are also included. The corresponding compounds (monomers and oligomers) are subjected to the reaction so as to obtain the desired composition. At this time, there are no restrictions on the timing and method of introducing the above optional components into the reaction system, and they are optional as long as the aliphatic polyester resin (A) can be produced.

For example, the timing and method of introducing the aliphatic oxycarboxylic acid into the reaction system is not particularly limited as long as it is before the polycondensation reaction between the diol component and the dicarboxylic acid component. (2) a method in which the catalyst is introduced into the reaction system at the time of charging the raw materials and mixed at the same time;

As for the timing of introduction of the compound forming the polyfunctional component unit, it may be charged at the same time as other monomers or oligomers in the initial stage of polymerization, or may be charged before starting pressure reduction after the transesterification reaction, but other monomers may be introduced. In terms of simplification of the process, it is preferable to charge simultaneously with or oligomer.

Aliphatic polyester resin (A) is usually produced in the presence of a catalyst. As the catalyst, any catalyst that can be used in the production of known polyester-based resins can be arbitrarily selected as long as the effects of the present invention are not significantly impaired. Metal compounds such as germanium, titanium, zirconium, hafnium, antimony, tin, magnesium, calcium, and zinc are suitable. Among them, germanium compounds and titanium compounds are preferable.

Germanium compounds that can be used as catalysts include, for example, organic germanium compounds such as tetraalkoxygermanium, and inorganic germanium compounds such as germanium oxide and germanium chloride. Among them, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are preferable in terms of price and availability, and germanium oxide is particularly preferable.

Examples of titanium compounds that can be used as catalysts include organic titanium compounds such as tetraalkoxy titanium such as tetrapropyl titanate, tetrabutyl titanate, tetraphenyl titanate and the like. Among them, tetrapropyl titanate, tetrabutyl titanate, and the like are preferable in terms of price and availability.

In addition, other catalysts may be used in combination as long as the object of the present invention is not impaired. In addition, a catalyst may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The amount of the catalyst used is arbitrary as long as it does not significantly impair the effects of the present invention. % by mass or less, preferably 1.5% by mass or less. Below the lower limit of this range, the effect of the catalyst may not appear, and above the upper limit, the production cost may increase, the resulting polymer may be markedly colored, and the hydrolysis resistance may decrease.

The introduction timing of the catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be introduced at the time of charging the raw materials or at the start of depressurization. When introducing an aliphatic oxycarboxylic acid unit, either introduce it at the same time as a monomer or oligomer that forms an aliphatic oxycarboxylic acid unit such as lactic acid or glycolic acid at the time of raw material charging, or dissolve the catalyst in an aqueous aliphatic oxycarboxylic acid solution. A method of dissolving the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introducing the catalyst is particularly preferable because the rate of polymerization increases.

Reaction conditions such as temperature, polymerization time, and pressure when producing the aliphatic polyester-based resin (A) are arbitrary as long as they do not significantly impair the effects of the present invention. And/or the reaction temperature of the transesterification reaction has a lower limit of usually 150° C. or higher, preferably 180° C. or higher, and an upper limit of usually 260° C. or lower, preferably 250° C. or lower. Moreover, the reaction atmosphere is usually an inert atmosphere such as nitrogen or argon. Furthermore, the reaction pressure is usually from normal pressure to 10 kPa, with normal pressure being preferred. The reaction time has a lower limit of generally 1 hour or longer and an upper limit of generally 10 hours or shorter, preferably 6 hours or shorter, and more preferably 4 hours or shorter. If the reaction temperature is too high, excessive formation of unsaturated bonds may occur, and gelation may occur due to the unsaturated bonds, making it difficult to control the polymerization.

Further, in the polycondensation reaction after the ester reaction and/or transesterification reaction between the dicarboxylic acid component and the diol component, the lower limit of the pressure is usually 0.01×10 ³ Pa or more, preferably 0.03×10 ³ Pa or more. , the upper limit of which is usually 1.4×10 ³ Pa or less, preferably 0.4×10 ³ Pa or less. In addition, the lower limit of the reaction temperature at this time is usually 150
°C or higher, preferably 180°C or higher, and the upper limit is usually 260°C or lower, preferably 250°C or lower. Furthermore, the lower limit of the reaction time is usually 2 hours or more, and the upper limit is usually 15 hours or less, preferably 10 hours or less. If the reaction temperature is too high, excessive formation of unsaturated bonds may cause gelation caused by the unsaturated bonds, making it difficult to control the polymerization.

A chain extender such as a carbonate compound or a diisocyanate compound may be used during the production of the aliphatic polyester resin (A). In this case, the amount of the chain extender is usually 10 as a ratio of carbonate bonds and urethane bonds in the aliphatic polyester resin (A) when the total structural units constituting the aliphatic polyester resin are 100 mol%. mol % or less, preferably 5 mol % or less, more preferably 3 mol % or less. However, the presence of urethane bonds and carbonate bonds in the aliphatic polyester resin (A) may inhibit biodegradability. Therefore, for all structural units constituting the aliphatic polyester resin (A), The carbonate bond is less than 1 mol%, preferably 0.5 mol% or less, more preferably 0.1 mol% or less, and the urethane bond is 0.55 mol% or less, preferably 0.3 mol% or less, more preferably is 0.12 mol % or less, more preferably 0.05 mol % or less. This amount is 0.9 parts by mass or less, preferably 0.5 parts by mass or less, more preferably 0.2 parts by mass or less, still more preferably 0 parts by mass when converted to 100 parts by mass of the aliphatic polyester resin (A). .1 part by mass or less. In particular, if the amount of urethane bonds exceeds the above upper limit, the decomposition of the urethane bonds in the film forming process, etc., may cause problems such as smoke and odor from the molten film from the die outlet. In some cases, film breakage due to foaming may occur and stable molding may not be possible.
The amount of carbonate bonds and the amount of urethane bonds in the aliphatic polyester-based resin (A) can be obtained by calculation from NMR measurement results such as ¹ H-NMR and ¹³ C-NMR.

Specific examples of the carbonate compound as the chain extender include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and ethylene carbonate. , diamyl carbonate, dicyclohexyl carbonate and the like. In addition, carbonate compounds composed of the same or different hydroxy compounds derived from hydroxy compounds such as phenols and alcohols can also be used.

Specific examples of diisocyanate compounds include 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, 2,4,6-triisopropylphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, tolidine diisocyanate, etc. are exemplified by the known diisocyanates of

Other chain extenders such as dioxazolines and silicate esters may also be used.
Specific examples of silicate esters include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane.

High-molecular-weight polyester resins using these chain extenders (coupling agents) can also be produced using conventional techniques. After completion of the polycondensation, the chain extender is added to the reaction system in a uniform molten state without a solvent, and reacted with the polyester obtained by the polycondensation.

More specifically, a terminal group obtained by catalytically reacting a diol component and a dicarboxylic acid component has substantially a hydroxyl group, and has a weight average molecular weight (Mw) of 20,000 or more, preferably 40,000. By reacting the above polyester with the chain extender, a polyester resin having a higher molecular weight can be obtained. Prepolymers with a weight-average molecular weight of 20,000 or more can be used with a small amount of a chain extender even under severe conditions such as a molten state. Molecular weight polyester resins can be produced. Here, the weight-average molecular weight (Mw) of the polyester-based resin is obtained as a value converted to monodisperse polystyrene from a value measured by gel permeation chromatography (GPC) at a measurement temperature of 40° C. using chloroform as a solvent.

Therefore, for example, when the diisocyanate compound described above is used as a chain extender to further increase the molecular weight of the polyester resin, a prepolymer having a weight average molecular weight of 20,000 or more, preferably 40,000 or more can be used. preferable. If the weight-average molecular weight is less than 20,000, the amount of the diisocyanate compound used to increase the molecular weight is increased, which may result in a decrease in heat resistance. Using such a prepolymer, a polyester resin having a urethane bond having a linear structure linked via a urethane bond derived from a diisocyanate compound is produced.

The pressure during chain extension is usually 0.01 MPa or more and 1 MPa or less, preferably 0.05 MPa or more and 0.5 MPa or less, more preferably 0.07 MPa or more and 0.3 MPa or less, but normal pressure is most preferable.

Regarding the reaction temperature during chain extension, the lower limit is usually 100°C or higher, preferably 150°C or higher, more preferably 190°C or higher, most preferably 200°C or higher, and the upper limit is usually 250°C or lower, preferably 240°C or lower. More preferably, it is 230° C. or less. If the reaction temperature is too low, the viscosity will be high, making uniform reaction difficult and high stirring power will be required.

The lower limit of chain extension time is usually 0.1 minute or more, preferably 1 minute or more, more preferably 5 minutes or more, and the upper limit is usually 5 hours or less, preferably 1 hour or less, more preferably 30 minutes or less. , most preferably 15 minutes or less. If the chain extension time is too short, the effect of adding the chain extender tends not to be exhibited, and if it is too long, the polyester resin tends to gel or decompose.

The molecular weight of the aliphatic polyester resin (A) can be measured by gel permeation chromatography (GPC). It is preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less, because it is advantageous in moldability and mechanical strength.

The melt flow rate (MFR) of the aliphatic polyester resin (A) is a value measured at 190° C. under a load of 2.16 kg based on JIS K7210 (1999), and is usually 0.1 g/10 min or more and 100 g/10 minutes or less, preferably 50 g/10 minutes or less, particularly preferably 40 g/10 minutes or less, from the viewpoint of moldability and mechanical strength. The MFR of the aliphatic polyester-based resin (A) can be adjusted by the molecular weight.

The melting point of the aliphatic polyester resin (A) is preferably 70°C or higher, more preferably 75°C or higher, and preferably 170°C or lower, more preferably 150°C or lower, and particularly preferably lower than 130°C. . When there are multiple melting points, at least one melting point is preferably within the above range.
Further, the elastic modulus of the aliphatic polyester resin (A) is preferably 180-1000 MPa.
If the melting point is outside the above range, moldability is poor, and if the elastic modulus is less than 180 MPa, problems with moldability tend to occur.

The method of adjusting the melting point and elastic modulus of the aliphatic polyester resin (A) is not particularly limited. It can be adjusted by adjusting the polymerization ratio or by combining them.

The aliphatic polyester resin (A) is not limited to one type, and two or more types of aliphatic polyester resins (A) having different constitutional unit types, constitutional unit ratios, production methods, physical properties, etc. can be blended and used.

<Aliphatic-aromatic polyester resin (B)>
As the aliphatic-aromatic polyester resin (B), at least part of the repeating units of the above-mentioned aliphatic polyester resin (A) is replaced with an aromatic compound unit, preferably the above-mentioned aliphatic A polyester containing an aliphatic diol unit, an aliphatic dicarboxylic acid unit and an aromatic dicarboxylic acid unit as main structural units, in which a part of the aliphatic dicarboxylic acid units of the polyester resin (A) is replaced with an aromatic dicarboxylic acid unit system resin is exemplified.

Examples of the aromatic compound unit include an aromatic diol unit having an optionally substituted aromatic hydrocarbon group, and an aromatic dicarboxylic acid having an optionally substituted aromatic hydrocarbon group. unit, an aromatic dicarboxylic acid unit having an optionally substituted aromatic heterocyclic group, an aromatic oxycarboxylic acid unit having an optionally substituted aromatic hydrocarbon group, and the like. . The aromatic hydrocarbon group and aromatic heterocyclic group may be monocyclic, or may be a combination of multiple rings bonded or condensed. Specific examples of the aromatic hydrocarbon group include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, dinaphthylene group, diphenylene group and the like. A specific example of the aromatic heterocyclic group includes a 2,5-furandyl group.

Specific examples of aromatic dicarboxylic acid components that provide aromatic dicarboxylic acid units include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 2,5-furandicarboxylic acid. Among them, terephthalic acid is preferred.

The aromatic dicarboxylic acid component may be a derivative of an aromatic dicarboxylic acid compound. For example, derivatives of the aromatic dicarboxylic acid components exemplified above are preferable, and among them, lower alkyl esters having 1 to 4 carbon atoms, acid anhydrides, and the like can be mentioned. Specific examples of derivatives of aromatic dicarboxylic acid compounds include lower alkyl esters such as methyl esters, ethyl esters, propyl esters and butyl esters of the aromatic dicarboxylic acid components exemplified above; aromatic dicarboxylic acids exemplified above such as succinic anhydride. Cyclic acid anhydrides of acid components; and the like. Among them, dimethyl terephthalate is preferred.

Specific examples of aromatic diol components that provide aromatic diol units include xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis(4′-hydroxyphenyl)propane, 2,2-bis( 4'-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, bis(4-β-hydroxyethoxyphenyl)sulfonic acid and the like. The aromatic diol component may be a derivative of an aromatic diol compound. A compound having a structure in which a plurality of aliphatic diol compounds and/or aromatic diol compounds are dehydrated and condensed with each other may also be used.

Specific examples of aromatic oxycarboxylic acid components that give aromatic oxycarboxylic acid units include p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid. The aromatic oxycarboxylic acid component may be a derivative of an aromatic oxycarboxylic acid compound. It may also be a compound (oligomer) having a structure in which a plurality of aliphatic oxycarboxylic acid compounds and/or aromatic oxycarboxylic acid compounds are dehydrated and condensed with each other. That is, an oligomer may be used as the raw material.

When optical isomers exist in the aromatic compound components that provide these aromatic compound units, any of the D-, L-, and racemic isomers may be used. Further, the aromatic compound component is not limited to the above examples as long as it can provide aromatic compound units. Furthermore, one aromatic compound component may be used alone, or two or more thereof may be used in any combination and ratio.

As the aliphatic-aromatic polyester resin (B), it is preferable to use an aromatic dicarboxylic acid component as a component that provides aromatic compound units. It is preferably 10 mol % or more and 80 mol % or less based on the total amount of units and aromatic dicarboxylic acid units (100 mol %). Further, it is preferable to use terephthalic acid or 2,5-furandicarboxylic acid as the aromatic dicarboxylic acid component. In that case, the aliphatic-aromatic polyester resin (B) is polybutylene terephthalate adipate and/or polybutylene. A terephthalate succinate resin is preferred. Polybutylene-2,5-furandicarboxylate-based resins are also preferred as the aliphatic-aromatic polyester-based resin (B).

The aliphatic-aromatic polyester resin (B) can be produced in the same manner as the above-described aliphatic polyester resin (A) using at least an aromatic compound component as a raw material.

The molecular weight of the aliphatic-aromatic polyester resin (B) can be measured by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) using monodisperse polystyrene as a standard is usually 10,000 or more and 1,000,000 or less, but since it is advantageous in terms of moldability and mechanical strength, it is preferably 30,000 or more and 800,000 or less, more preferably 50,000 or more and 600,000 or less. .

The melt flow rate (MFR) of the aliphatic-aromatic polyester resin (B) is JIS
Based on K7210 (1999), the value measured at 190 ° C. and a load of 2.16 kg is usually 0.1 g / 10 minutes or more and 100 g / 10 minutes or less, but from the viewpoint of moldability and mechanical strength, preferably 50 g /10 minutes or less, particularly preferably 30 g/10 minutes or less. The MFR of the aliphatic-aromatic polyester resin (B) can be adjusted by the molecular weight.

The melting point of the aliphatic-aromatic polyester resin (B) is usually 60°C or higher, preferably 70°C or higher, more preferably 80°C or higher, and preferably 150°C or lower, more preferably 140°C. Below, it is 120 degrees C or less especially preferably. When there are multiple melting points, at least one melting point is preferably within the above range.
The elastic modulus of the aliphatic-aromatic polyester resin (B) is preferably 180-1000 MPa.
If the melting point is outside the above range, moldability is poor, and if the elastic modulus is less than 180 MPa, problems with moldability tend to occur.

The method of adjusting the melting point and elastic modulus of the aliphatic-aromatic polyester resin (B) is not particularly limited, but for example, the type of copolymerization component of an aliphatic dicarboxylic acid component other than the aromatic dicarboxylic acid component is selected, It is possible to adjust by adjusting each copolymerization ratio or by combining them.

The aliphatic-aromatic polyester resin (B) is not limited to one type, and two or more types of aliphatic-aromatic polyester resins (B) having different types of structural units, structural unit ratios, manufacturing methods, physical properties, etc. It can be used by blending.

<Aliphatic oxycarboxylic acid-based resin (C)>
The aliphatic oxycarboxylic acid-based resin (C) has aliphatic oxycarboxylic acid units as main structural units, and the aliphatic oxycarboxylic acid units are preferably represented by the following formula (3).
-OR ³ -CO- (3)
(In formula (3) above, R ³ represents a divalent aliphatic hydrocarbon group or a divalent alicyclic hydrocarbon group.)

Specific examples of the aliphatic oxycarboxylic acid component that gives the aliphatic oxycarboxylic acid unit of formula (3) include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 2-hydroxy-3, 3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, 6-hydroxycaproic acid, mixtures thereof, and the like. When optical isomers exist in these, either D-isomer or L-isomer may be used. Preferred among these are lactic acid and 6-hydroxycaproic acid. These aliphatic oxycarboxylic acid components can also be used in combination of two or more.

In addition, urethane bonds, amide bonds, carbonate bonds, ether bonds and the like can be introduced into the aliphatic oxycarboxylic acid resin (C) within a range that does not affect biodegradability.

The method for producing the aliphatic oxycarboxylic acid-based resin (C) is not particularly limited, and it can be produced by a known method such as a direct polymerization method of oxycarboxylic acid or a ring-opening polymerization method of a cyclic body.

The molecular weight of the aliphatic oxycarboxylic acid-based resin (C) can be measured by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) using monodisperse polystyrene as a standard substance is usually 10. ,000 or more and 1,000,000 or less, preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less, because they are advantageous in terms of moldability and mechanical strength.

The melt flow rate (MFR) of the aliphatic oxycarboxylic acid-based resin (C) is a value measured at 190° C. and a load of 2.16 kg based on JIS K7210 (1999), and is usually 0.1 g/10 min or more and 100 g /10 minutes or less, preferably 50 g/10 minutes or less, particularly preferably 40 g/10 minutes or less from the viewpoint of moldability and mechanical strength. The MFR of the aliphatic oxycarboxylic acid resin (C) can be adjusted by the molecular weight.

The melting point of the aliphatic oxycarboxylic acid resin (C) is preferably 50°C or higher, more preferably 55°C or higher, and preferably 200°C or lower, more preferably 190°C or lower, and particularly preferably less than 180°C. is. When there are multiple melting points, at least one melting point is preferably within the above range.
The elastic modulus of the aliphatic oxycarboxylic acid resin (C) is preferably 180-4000 MPa.
If the melting point is outside the above range, moldability is poor, and if the modulus of elasticity is less than 180 MPa, problems with moldability tend to occur.

The method of adjusting the melting point and elastic modulus of the aliphatic oxycarboxylic acid-based resin (C) is not particularly limited. Adjustments can be made by adjusting the ratio or by combining them.

As the aliphatic oxycarboxylic acid-based resin (C), polyhydroxyalkanoate (D) described below can also be preferably used.
Polyhydroxyalkanoate (hereinafter sometimes referred to as PHA) (D) has the general formula: [-CHR-CH ₂ -CO-O-] (wherein R is an alkyl group having 1 to 15 carbon atoms ) and is a copolymer containing a 3-hydroxybutyrate unit as a main structural unit.

Polyhydroxyalkanoate (D) preferably contains 80 mol % or more, more preferably 85 mol % or more, of 3-hydroxybutyrate units as a constituent component from the viewpoint of moldability and thermal stability. Also, those produced by microorganisms are preferred. Specific examples of polyhydroxyalkanoate (D) include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyvalerate- co-3-hydroxyhexanoate) copolymer resin and the like.
In particular, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, ie, PHBH, is preferred from the viewpoint of molding processability and physical properties of the resulting molded product.

In the polyhydroxyalkanoate (D), 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) and comonomers such as 3-hydroxyhexanoate (hereinafter sometimes referred to as 3HH) copolymerized , that is, the monomer ratio in the copolymer resin, from the viewpoint of molding processability and molded product quality, 3-hydroxybutyrate / comonomer = 97/3 to 80/20 (mol% / mol%) and more preferably 95/5 to 85/15 (mol%/mol%). If the comonomer ratio is less than 3 mol %, molding may be difficult because the molding temperature and the thermal decomposition temperature are close to each other. When the comonomer ratio exceeds 20 mol %, the crystallization of the polyhydroxyalkanoate (D) slows down, which may deteriorate the productivity.

Each monomer ratio in the polyhydroxyalkanoate (D) can be measured by gas chromatography as follows.
To about 20 mg of dry PHA, 2 ml of a mixture of sulfuric acid/methanol (15/85 (mass ratio)) and 2 ml of chloroform are added, and the mixture is tightly stoppered and heated at 100° C. for 140 minutes to obtain a methyl ester of a PHA decomposition product. After cooling, 1.5 g of sodium bicarbonate is added little by little to neutralize and allowed to stand until the evolution of carbon dioxide ceases. After adding 4 ml of diisopropyl ether and mixing well, the monomer unit composition of the PHA decomposition product in the supernatant is analyzed by capillary gas chromatography to determine the ratio of each monomer in the copolymer resin.

The weight average molecular weight (hereinafter sometimes referred to as Mw) of the polyhydroxyalkanoate (D) can be measured by the gel permeation chromatography (GPC) described above, using monodisperse polystyrene as a standard substance. The weight average molecular weight (Mw) is usually 200,000 or more and 2,500,000 or less, but is advantageous in terms of moldability and mechanical strength, so it is preferably 250,000 or more and 2,000,000 or less, more It is preferably 300,000 or more and 1,000,000 or less. If the weight-average molecular weight is less than 200,000, the mechanical properties may be poor, and if it exceeds 2,500,000, molding may become difficult.

The melt flow rate (MFR) of the polyhydroxyalkanoate (D) is a value measured at 190°C under a load of 2.16 kg based on JIS K7210 (1999), and is preferably 1 g/10 min or more and 100 g/10 min or less. However, from the viewpoint of moldability and mechanical strength, it is more preferably 80 g/10 minutes or less, particularly preferably 50 g/10 minutes or less. The MFR of polyhydroxyalkanoate (D) can be adjusted by the molecular weight.

The melting point of the polyhydroxyalkanoate (D) is preferably 100°C or higher, more preferably 120°C or higher, and preferably 180°C or lower, more preferably 170°C or lower, particularly preferably lower than 160°C. When there are multiple melting points, at least one melting point is preferably within the above range.

Polyhydroxyalkanoate (D) is, for example, Alcaligenes eutrophus AC32 strain (international deposit based on the Budapest Treaty, international depository authority: National Institute of Advanced Industrial Science and Technology Patent Biological Depositary Center (1-1-1-Central 6, Higashi Tsukuba City, Ibaraki Prefecture, Japan) Transferred from deposit FERM P-15786)) (J. Bacteriol., 179, 4821 (1997)).

A commercially available product can also be used as the polyhydroxyalkanoate (D). , "PHBH X331N", "PHBH X131A", and "PHBH X151A" manufactured by Kaneka Corporation can be used.

In the present embodiment, the aliphatic oxycarboxylic acid-based resin (C) including the polyhydroxyalkanoate (D) is not limited to one type, and two different types of structural units, structural unit ratios, production methods, physical properties, etc. More than one kind of aliphatic oxycarboxylic acid resin (C) can be blended and used.

<Other ingredients>
In addition to the galactomannan described above, the biodegradable resin composition contains fillers (fillers), plasticizers, antistatic agents, antioxidants, light stabilizers, ultraviolet absorbers, dyes, pigments, hydrolysis inhibitors, Various additions such as crystal nucleating agents, anti-blocking agents, weathering agents, heat stabilizers, flame retardants, mold release agents, anti-fogging agents, surface wettability improving agents, combustion aids, dispersing aids, various surfactants, slip agents, etc. One or more agents may be included as "other ingredients".
The biodegradable resin composition may also contain a freshness-keeping agent, an antibacterial agent, and the like as functional additives.

These other components can be arbitrarily blended within a range that does not impair the effects of the present invention, and may be used singly or in combination of two or more.

The content of these other components in the biodegradable resin composition usually does not impair the physical properties of the biodegradable resin composition, so the total amount of the other components is It is preferably 0.01% by mass or more and 40% by mass or less with respect to the total amount.

<Method for producing biodegradable resin composition>
The biodegradable resin composition is produced by kneading the biodegradable resin and galactomannan in a kneader to disperse the galactomannan in the biodegradable resin. In addition, other resins and other components used as necessary may be mixed in the kneader together with the galactomannan and the biodegradable resin.

In this mixing step, the galactomannan and the biodegradable resin, and other resins and other components that are used as necessary, are mixed in a predetermined ratio at the same time or in any order, in a tumbler, a V-type blender, a Nauta mixer. , a Banbury mixer, a kneading roll, an extruder or the like, and preferably further melt-kneaded.

The kneader used in the mixing step may be a melt kneader. The extruder may be either a twin-screw extruder or a single-screw extruder, but a twin-screw extruder is more preferred.

The temperature during melt-kneading is preferably 140 to 220°C. Within this temperature range, the time required for the melting reaction can be shortened, the deterioration of the resin and the deterioration of the color tone due to the carbonization of the galactomannan can be prevented, and the impact resistance, moist heat resistance, etc. can be improved. Physical properties in practical use can be further improved. From the same point of view, the melt-kneading temperature is more preferably 150 to 210°C.

In addition, the melt-kneading time should be avoided from the viewpoint of avoiding deterioration of the resin more reliably as described above, and is preferably 20 seconds or more and 20 minutes or less, more preferably 30 seconds. 15 minutes or less. Therefore, it is preferable to set the melt-kneading temperature and time so as to satisfy the melt-kneading conditions.

The galactomannan is desirably powdered in advance before being mixed with the biodegradable resin. By doing so, the galactomannan is uniformly dispersed in the biodegradable resin composition, and a molded article having excellent biodegradability and excellent mechanical properties and appearance can be obtained.

Methods for obtaining powdery galactomannan include, for example, a method of pulverizing with a pulverizer such as a stone mill, a cutter mill, a jet mill, or a crush mill; a method of spray drying an aqueous solution; There are methods such as precipitation. The particle size of the powdery galactomannan is usually 500 μm or less, preferably 300 μm or less, more preferably 100 μm or less, from the viewpoint of being more easily mixed with the biodegradable resin and easily obtaining the effect of promoting biodegradation. be. In order to obtain good mechanical properties and appearance as well as the effect of promoting biodegradation, the particle size is preferably 15 μm or less, particularly preferably 10 μm or less. Various known methods such as a sieving method, a laser diffraction method, and a microscopy method can be used to measure the particle size of the galactomannan.

Also, the galactomannan is preferably dried in advance before being mixed with the biodegradable resin. If the drying is insufficient, the biodegradable resin hydrolyzes when mixed with the biodegradable resin, resulting in a decrease in molecular weight and insufficient mechanical strength. The moisture content of the dried galactomannan is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

Galactomannan can be dried using, for example, batch-type dryers such as hot-air dryers, vacuum dryers and inert ovens, and continuous dryers such as vibrating fluidized-bed dryers, flash dryers and cylindrical dryers. . The drying temperature is usually in the range of 40°C to 200°C. If the drying temperature is too low, the drying efficiency will decrease, and if the drying temperature is too high, problems such as poor appearance due to discoloration and generation of odor due to deterioration may occur.

[Molded body]
The biodegradable resin composition can be molded by various molding methods applied to general-purpose plastics. Examples of the molding method include compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding and co-extrusion molding (film molding by inflation method or T-die method, laminate molding, pipe molding, wire / cable molding , profiled material molding), hot press molding, blow molding (various blow molding), calendar molding, solid molding (uniaxial stretching molding, biaxial stretching molding, roll rolling molding, stretch orientation nonwoven fabric molding, thermoforming (vacuum molding, air pressure molding) molding), plastic processing, powder molding (rotation molding), various non-woven fabric molding (dry method, adhesion method, entanglement method, spunbond method, etc.), etc. Among them, injection molding, extrusion molding, compression molding, or hot press Molding, especially extrusion molding or injection molding, is preferably applied, and as specific shapes, application to sheets, films and containers is preferred.

In addition, the biodegradable resin molding obtained by molding the biodegradable resin composition has chemical functions, electrical functions, magnetic functions, mechanical functions, friction/wear/lubricating functions, optical functions, heat It is also possible to perform various secondary processing for the purpose of imparting surface functions such as biocompatibility and biocompatibility. Examples of secondary processing include embossing, painting, adhesion, printing, metallizing (plating, etc.), machining, surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

[Use]
Biodegradable resin moldings are suitably used in a wide range of applications such as packaging materials for packaging liquids, powders, and solids such as various foods, medicines, miscellaneous goods, agricultural materials, and construction materials. Specific uses include injection molded products (e.g. fresh food trays, fast food containers, coffee capsule containers, cutlery, outdoor leisure products, etc.), extrusion molded products (e.g. films, sheets, fishing lines, fishing nets, etc.). vegetation nets, secondary processing sheets, water-retaining sheets, etc.), hollow molded products (bottles, etc.), and the like. In addition, other agricultural films, coating materials, fertilizer coating materials, nursery pots, laminated films, boards, stretched sheets, monofilaments, nonwoven fabrics, flat yarns, staples, crimped fibers, creased tapes, split yarns, composite fibers, Blown bottles, shopping bags, garbage bags, compost bags, cosmetic containers, detergent containers, bleach containers, ropes, binding materials, sanitary coverstock materials, cooler boxes, cushioning films, multifilament, synthetic paper, medical surgeries Threads, sutures, artificial bones, artificial skins, DDS such as microcapsules, wound dressings, and the like.

In particular, it is suitable as a packaging material for shopping bags, packaging films, fresh food trays, fast food containers, lunch boxes and the like.

EXAMPLES The content of the present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited by the following examples as long as the gist thereof is not exceeded. Various production conditions and values of evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention. It may be a range defined by the value of the example or a combination of the values of the examples.

[Biodegradable resin]
As biodegradable resins, the following aliphatic polyester resin (A), aliphatic-aromatic polyester resin (B), and aliphatic oxycarboxylic acid resin (C) were used.
Aliphatic polyester resin (A)-1: Polybutylene succinate adipate (PBSA) "BioPBS FD92PM" manufactured by PTTMCC Biochem
Aliphatic polyester resin (A)-2: Polybutylene succinate (PBS) "BioPBS FZ91PM" manufactured by PTTMCC Biochem
Aliphatic-aromatic polyester resin (B): polybutylene adipate terephthalate (PBAT) BASF "ecoflex F Blend C1200"
Aliphatic oxycarboxylic acid-based resin (C): Polylactic acid (PLA) "Ingeo 4060D" manufactured by NatureWorks

[Galactomannan]
As the galactomannan, powder obtained by passing the following materials through a sieve with an opening of 150 μm was used.
Galactomannan-1 (guar gum): "Guar gum (purified product) RG100" manufactured by Mitsubishi Chemical Foods Co., Ltd. Weight average molecular weight: 260,000
Galactomannan-2 (Locust bean gum): "Soar Locust A220C" manufactured by Mitsubishi Chemical Foods Co., Ltd. Weight average molecular weight: 300,000
Galactomannan-3 (guar gum): "Guar gum" manufactured by Tokyo Chemical Industry Co., Ltd. Weight average molecular weight: 210,000
Galactomannan-4 (locust bean gum): Fujifilm Wako Pure Chemical Industries, Ltd. “Locust bean gum” Weight average molecular weight: 250,000

[Other ingredients]
As polysaccharides and monosaccharides other than galactomannan, powders obtained by passing the following materials through a sieve with an opening of 150 μm were used.
Cellulose: "KC Flock W-400Y" manufactured by Nippon Paper Industries Co., Ltd.
Starch: "Starch (soluble)" manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.
Glucose: Fujifilm Wako Pure Chemical Co., Ltd. "D (+)-glucose" (ground in a mortar)

[Biodegradability test]
The biodegradability of the biodegradable resin composition was evaluated by the following two methods.
<Home compost biodegradability test>
A sheet-shaped resin composition was cut into a rectangle of 50 mm x 30 mm, and was placed in a polyethylene Tupperware container. Yawata Bussan Co., Ltd., inoculum for biodegradation test) was buried in a mixture with a mass ratio of 1:1, closed with a lid, and allowed to stand in a constant temperature bath at 28°C for 2 weeks. For each test piece, the weight change before and after standing was measured, and the weight loss rate (ratio of weight loss to weight before standing) was calculated. In addition, since the rate of biodegradation may vary depending on the test lot, even with the same composition, the relative ratio to the weight reduction rate in the comparative example consisting of only biodegradable resin that was tested at the same time was calculated. It was also described as a degradability improvement rate.

<Marine biodegradability test>
Seawater was sampled at a sandy beach (around 34.94 degrees north latitude and 136.64 degrees east longitude) in Yokkaichi Port, Yokkaichi City, Mie Prefecture, and filtered through a nylon mesh with an opening of 11 μm. In addition, sea sand under the sea surface of the same sandy beach is collected, sand grains under the sieve with a mesh size of 2 mm and above a sieve with a mesh size of 0.3 mm are selected, washed with filtered seawater to remove floating matter. removed. A glass water tank (width 60 cm, depth 30 cm, height 23 cm) equipped with a seawater circulation device, a temperature control device, and an air stone was laid with sea sand to a thickness of about 1 cm. ) to make a test tank.
A 30 mm square test piece was cut out of the resin composition molded into a sheet shape, and placed on sand. Seawater was circulated while air was blown in from an air stone. In addition, in order to prevent difficulty in recovering the test piece that has begun to disintegrate due to progressing decomposition, it is put into a polyethylene mesh bag with an opening of about 1.2 mm, together with pebbles as a weight, and tested. continued.

The weight loss per unit area (mg/cm ² ) was calculated by measuring the weight of the test piece before and after the test and dividing the amount of weight loss by the total surface area of the front and back surfaces of the test piece. The calculation formula is as follows.
Weight loss per unit area (mg/cm ² ) = (weight loss (g) x 10 ³ )/(30 x 30 x 2 x 10 ^-2 )
In addition, the rate of biodegradation may change even if the composition is the same if the timing of water sampling or testing is different. was calculated as the marine biodegradability improvement rate.

[Examples 1 to 4, Comparative Examples 1 to 4]
A biodegradable resin, galactomannan or other components are blended at the ratios shown in Tables 1 and 2, and a small twin-screw kneader (manufactured by DSM "Xplore Micro 15cc Twin
Screw Compounder") was used to perform melt-kneading at 170° C. for 4 minutes in a nitrogen atmosphere. The resulting resin composition was molded into a sheet having a thickness of about 120 μm with a hot press molding machine at 170°C.

The sheet-shaped compacts obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to the above home compost biodegradability test, and the results are shown in Tables 1 and 2.

[Examples 5 to 9, Comparative Examples 5 to 11]
A biodegradable resin, galactomannan or other components are blended at the ratios shown in Tables 3 and 4, and a small twin-screw kneader (manufactured by DSM "Xplore Micro 15cc Twin
Screw Compounder") was used to perform melt-kneading at 170° C. for 4 minutes in a nitrogen atmosphere. The resulting resin composition was molded into a sheet having a thickness of about 120 μm with a hot press molding machine at 170°C.

The sheet-shaped moldings obtained in Examples 5-9 and Comparative Examples 5-11 were subjected to the above marine biodegradability test, and the results are shown in Tables 3-5.

[Example 10, Comparative Examples 12 to 14]
Biodegradable resin and galactomannan are blended in the proportions shown in Table 6, and are compounded at 190°C under a nitrogen atmosphere using a small twin-screw kneader (manufactured by DSM, "Xplore Micro 15cc Twin Screw Compounder"). Melt-kneading was performed for a minute. The resulting resin composition was molded into a sheet having a thickness of about 120 μm with a hot press molding machine at 190°C.

For the sheet-shaped compacts obtained in Example 10 and Comparative Examples 12 to 14, the test period of the home compost biodegradability test was changed to 18 weeks, and the marine biodegradability test was performed. The results are shown in Table 6.

From Tables 1 to 6, the biodegradable resin composition of the present invention containing galactomannan in a predetermined ratio to the biodegradable resin promotes biodegradation more than conventional biodegradable resins in home compost and the sea. , has excellent biodegradability.

Claims (7)

A biodegradable resin composition containing a biodegradable resin and a galactomannan, wherein the biodegradable resin is a polyester containing structural units derived from a diol and structural units derived from a dicarboxylic acid as main structural components, , A biodegradable resin composition containing more than 0.1 parts by mass and 30 parts by mass or less of galactomannan with respect to 100 parts by mass of the biodegradable resin. 2. The biodegradable resin composition according to claim 1, wherein said galactomannan is one or more selected from the group consisting of fenugreek gum, guar gum, tara gum, locust bean gum and cassia gum. 3. The biodegradable resin composition according to claim 1, wherein said diol is an aliphatic diol and said dicarboxylic acid is an aliphatic dicarboxylic acid and/or an aromatic dicarboxylic acid. The biodegradable resin composition according to any one of claims 1 to 3, wherein the biodegradable resin is an aliphatic polyester resin (A) and/or an aliphatic - aromatic polyester resin (B). . A biodegradable resin molded article, which is an extruded or injection molded article of the biodegradable resin composition according to any one of claims 1 to 4. A biodegradable resin composition containing a biodegradable resin and a galactomannan, wherein the biodegradable resin is an aliphatic oxycarboxylic acid-based resin, and galactomannan is added to 100 parts by mass of the biodegradable resin A biodegradable resin composition containing more than 0.1 parts by mass and 6.6 parts by mass or less of mannan. A method for producing a biodegradable resin composition, comprising a step of melt-kneading a biodegradable resin and galactomannan powder.