JP2024033227A - Biodegradable film and lid material - Google Patents

Abstract

[Problem] The problem to be solved by the present invention is to realize easy openability (easy peelability) due to stable cohesive failure over a wide range of heat sealing temperatures for various containers using biodegradable polyester resin, Another object of the present invention is to provide a biodegradable film that has good rigidity, film formability, impact resistance, blocking resistance, etc., and can be suitably used for packaging purposes. [Solution] The present invention includes a heat-sealing layer (A) containing a biodegradable polyester resin, a fluidity modifier, and an inorganic filler, and the inorganic filler is contained in the heat-sealing layer (A). 10% by mass or more, the fluidity modifier is a polyester having a carboxyl group at at least one end, and the ratio of the inorganic filler to the fluidity modifier is inorganic filler/fluidity modifier. The above-mentioned problem is solved by a biodegradable film characterized in that the agent is in the range of 1 to 20. [Selection diagram] None

Description

The present invention relates to a biodegradable film that has good adhesion to adherends such as the heat-sealed portion of a biodegradable packaging container, and can be easily peeled and easily opened. It is.

Conventionally, materials such as polyethylene, polypropylene, and polyethylene terephthalate have been widely used for various plastic packaging materials such as packaging bags and packaging containers. In recent years, these plastic packaging materials have a large impact on the environment, as they use fossil resources as raw materials and do not decompose for a long time if discarded in the environment, so the use of plant-derived raw materials has become increasingly popular. The use of materials with low environmental impact is being considered, such as bioresins that have a low environmental impact, and biodegradable resins that decompose in soil or water through hydrolysis or biodegradation.

In addition, packaging materials and lid materials for packaging containers are required to have easy-to-open properties that allow them to be opened without applying force. Means for imparting easy-openability include an interlayer peeling type in which the seal layer peels off from a base layer directly laminated thereon, and an interfacial peeling type in which peeling occurs between the seal layer and the adherend. It is broadly classified into the cohesive failure type, in which the sealing layer is destroyed and peeled off. Interfacial peeling type lidding materials generally tend to exhibit large fluctuations in sealing strength due to the effects of sealing temperature and sealing pressure, and are also susceptible to the surface condition of the adherend. On the other hand, a cohesive failure type seal layer has relatively excellent stability in sealing strength and is also excellent in sealing off foreign substances. Furthermore, the cohesive failure type has the advantage that the peeled area turns white and leaves clear peeling marks, which serves as proof that the package has been opened and prevents tampering.

As an easy-to-open packaging material that is environmentally friendly, the applicant has developed a packaging material that has heat-sealing properties and easy-to-open properties that are suitable for various materials including environmentally friendly materials. We are developing a laminated film that can be suitably used for various purposes (see Patent Document 1). However, the laminated film described in Patent Document 1 is a film that is easily opened due to interfacial peeling, and the sealing strength may fluctuate due to the effects of sealing temperature and sealing pressure. Furthermore, the sealing strength and airtightness of the laminated film may deteriorate due to the influence of foreign substances. Furthermore, the laminated film does not leave any marks at the location where it is peeled off, and does not have a tamper-proofing function.

Further, as a cohesive failure type laminated film, a film containing inorganic fine particles and a dispersant in a thermoplastic resin has been disclosed (see Patent Document 2). However, since biodegradable resins, especially biodegradable polyester resins, are generally highly polar, they have poor fluidity and tend to be difficult to mix with inorganic fillers. It could not be applied to other resins.

WO2021/002206 publication JP2015-63125A

The problem to be solved by the present invention is to realize easy openability (easy peelability) due to stable cohesive failure over a wide range of heat sealing temperatures for various containers using biodegradable polyester resin, and to achieve good peelability. The object of the present invention is to provide a biodegradable film that has rigidity, film formability, impact resistance, blocking resistance, etc. and can be suitably used for packaging purposes.

The present invention includes a heat-sealing layer (A) containing a biodegradable polyester resin, a fluidity modifier, and an inorganic filler, and the inorganic filler is contained in the heat-sealing layer (A) in an amount of 10% by mass or more. and the fluidity modifier is a polyester having a carboxyl group at at least one end, and the ratio of the inorganic filler to the fluidity modifier is inorganic filler/fluidity modifier = 1 to The above-mentioned problem is solved by a biodegradable film characterized in that the molecular weight is within the range of 20.

The biodegradable film of the present invention has good rigidity, film formability, impact resistance, blocking resistance, etc., and can be suitably used for packaging purposes. Furthermore, the biodegradable film of the present invention has stable heat-sealability and easy-opening properties over a wide temperature range, and therefore can be suitably used as various packaging materials. Furthermore, since it is possible to achieve easy opening due to cohesive failure over a wide range of heat-sealing temperatures, production line control is easy.

Furthermore, since the biodegradable film of the present invention is of a cohesive failure type, it is less affected by the surface condition of the adherend than an interfacial peeling type, and has excellent contaminant sealing properties. Furthermore, the cohesive failure type is particularly suitable for food and medical packaging applications because the peeled areas turn white, which serves as proof of tampering and prevents tampering.

Furthermore, the biodegradable film of the present invention contains a biodegradable resin in the heat-sealing layer, and the resin layer laminated with the heat-sealing layer also contains a biodegradable resin. It is also highly environmentally friendly.

The biodegradable film of the present invention includes a heat-sealing layer (A) containing a biodegradable polyester resin, a fluidity modifier, and an inorganic filler, and the inorganic filler is contained in the heat-sealing layer (A). 10% by mass or more, the fluidity modifier is a polyester having a carboxyl group at at least one end, and the ratio of the inorganic filler to the fluidity modifier is inorganic filler/fluidity modifier. The biodegradable film is characterized in that the quality factor is in the range of 1 to 20.

[Heat seal layer (A)]
The heat seal layer (A) used in the present invention contains a biodegradable polyester resin, a fluidity modifier, and an inorganic filler. When the heat seal layer (A) is sealed to an adherend, cohesive failure occurs when the seal is opened, thereby realizing easy opening.

[Biodegradable polyester resin]
In the present invention, "biodegradable" means that it can be decomposed down to the molecular level by the action of microorganisms present in soil, water, the ocean, etc.
Examples of the biodegradable polyester resin used in the heat seal layer (A) of the present invention include polylactic acid resin, polybutylene succinate resin, and other biodegradable polyester resins. Among these, polylactic acid resins and polybutylene succinate resins are preferred, and polybutylene succinate resins are more preferred. It is also preferable to use a polylactic acid resin and a polybutylene succinate resin together.

Examples of the polylactic acid resin include polylactic acid (poly(D-lactic acid), poly(L-lactic acid)), copolymers of D-lactic acid and L-lactic acid, and copolymers of D-lactic acid and other hydroxycarboxylic acids. Examples include copolymers, copolymers of L-lactic acid and other hydroxycarboxylic acids, and polymers obtained by copolymerizing a polyester component obtained by ester reacting a dicarboxylic acid and a diol with a lactic acid component. Among these, polylactic acid is preferred from the viewpoint of film formation stability and availability, and polylactic acid whose main structural unit is L-lactic acid is more preferred. These polymers may be used alone or in combination.

Examples of the hydroxycarboxylic acids, diols, and dicarboxylic acids include hydroxycarboxylic acids such as hydroxycaproic acids such as glycolic acid, hydroxybutyric acid, and hydroxycaproic acid; hydroxycarboxylic acids such as cyclic lactones such as caprolactone, butyrolactone, lactide, and glycolide; ethylene glycol; Aliphatic diols such as propylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalene dicarboxylic acid; succinic acid, adipic acid, suberic acid, and sebacic acid Examples include aliphatic dicarboxylic acids such as.

The polylactic acid resin has a melt flow rate (190°C, 21.18N) of preferably 0.5 to 30 g/10 minutes, more preferably 2 to 25 g because it can easily achieve good fluidity during extrusion molding. /10 minutes. When the melt flow rate is within this range, extrusion molding is easy, and when multi-layered by coextrusion, a biodegradable film with good fluidity with adjacent layers and an excellent appearance can be easily obtained.

Further, the density of the polylactic acid resin is preferably 1.20 to 1.26 g/cm ³ , more preferably 1.23 to 1.25 g/cm ³ .

Examples of the polybutylene succinate resin include poly(butylene succinate) (PBS) and poly(butylene succinate/adipate) copolymer (PBSA). The poly(butylene succinate) is a polycondensate of 1,4-butanediol and succinic acid, and the poly(butylene succinate/adipate) copolymer is a polycondensate of 1,4-butanediol and succinic acid. , is a polycondensate with adipic acid added. Such poly(butylene succinate and poly(butylene succinate/adipate) copolymers) can be made to have a high molecular weight using lactic acid or a polyfunctional isocyanate compound in order to increase the molecular weight, and can be adjusted to an appropriate molecular weight.

The melt flow rate (190°C, 21.18N) of the polybutylene succinate resin is preferably about 0.5 to 25 g/10 minutes from the viewpoint of film extrusion moldability, and more preferably 1 to 20 g/10 minutes. .

Further, the density of the polybutylene succinate resin is preferably 1.20 to 1.29 g/cm ³ , more preferably 1.21 to 1.27 g/cm ³ .

(Other biodegradable polyester resins)
Examples of the other biodegradable polyester resins include aliphatic polyester compounds such as polyglycolic acid, polycaprolactone, ring-opening polymers such as β-propiolactone and γ-valerolactone; adipic acid and 1.4 - Copolyester of butanediol and terephthalic acid (polybutylene adipate terephthalate), polyester of succinic acid and ethylene glycol (polyethylene succinate), polyester of adipic acid and 1,4-butanediol, succinic acid and 1. Examples include polyesters made of an aliphatic dibasic acid and aliphatic diol, such as polyesters made of 6-hexanediol; and copolymers thereof.

Further, as a copolymer of an aliphatic polyester and an aromatic polyester, the above-mentioned aliphatic polyester compound or 1 to 50% by mass, preferably 5 to 30% by mass of terephthalic acid or isophthalic acid when synthesized. Examples include resins reacted with aromatic dicarboxylic acids and aromatic oxycarboxylic acids such as naphthalene dicarboxylic acid, P-hydroxybenzoic acid, P-hydroxyethylbenzoic acid, and P-hydroxyphenylacetic acid.

Examples of copolymers of polylactic acid and aliphatic polyester include polylactic acid and ethylene glycol, 1,2-butylene glycol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, triethylene glycol, dipropylene glycol, and dipropylene glycol. Polyhydric alcohols such as butanediol and polytetramethylene glycol, and polyhydric alcohols such as succinic acid, methylglutaric acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, maleic anhydride, and fumaric acid. Examples include copolymers of aliphatic polyesters obtained from carboxylic acids. Polymerization catalysts used in the production of lactic acid-based polyesters include, for example, metals such as tin, zinc, lead, titanium, bismuth, zirconium, germanium, cobalt, etc., known as transesterification catalysts, and their compounds, especially metal organic compounds, and carbonic acid. Salts, halides, among others tin octoate, zinc chloride, alkoxy titanium, etc. may be mentioned.

As the biodegradable polyester resin used in the present invention, commercially available products may be used. Commercially available products include the "PLAXEL" series (polycaprolactone, manufactured by Daicel Corporation), "BIOMAX" (modified polyester, manufactured by DuPont), and the like.

The content of the biodegradable polyester resin in the heat-sealing layer (A) is preferably 80% by mass or more, and preferably 90% by mass or more of the resin component contained in the heat-sealing layer (A). More preferred. In addition, when using multiple biodegradable polyester resins together, it is preferable that the total content is 80% by mass or more, and 90% by mass or more in the resin component contained in the heat seal layer (A). It is more preferable that there be some, and the resin component may substantially consist only of these resins. With such a content, biodegradability can be exhibited, leading to a reduction in environmental load.

(Other biodegradable resins)
The heat-sealing layer (A) may contain other biodegradable resins other than those mentioned above to the extent that the effects of the present invention are not impaired. Examples of other biodegradable resins include poly(3-hydroxybutyric acid), copolymers of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, copolymers of 3-hydroxybutyric acid and 4-hydroxybutyric acid, etc. Polyhydroxyalkanoates; polyvinyl alcohol; pullulan; natural biodegradable resins such as chitosan, starch-based green plastic, esterified starch, cellulose, and cellulose acetate; and the like.

The other biodegradable resins mentioned above may be used alone or in combination.
Furthermore, commercially available products may be used as the other biodegradable resins mentioned above. Commercially available products include "Matabee" (starch-based, manufactured by Novamont), "Exeval" (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), "Pullulan" (manufactured by Hayashibara Co., Ltd.), and the like.

When using the above-mentioned other biodegradable resins, it is preferably less than 20% by mass, more preferably less than 10% by mass in the resin component contained in the heat seal layer (A). With such a content, it becomes easy to obtain suitable heat-sealability, easy-openability, impact resistance, etc. for various materials.

(Other resins)
Further, the heat-sealing layer (A) may contain resins other than the above-mentioned biodegradable resins to the extent that the effects of the present invention are not impaired. Preferred examples of the other resins include polyolefin resins such as polyethylene resins and polypropylene resins, and polyester resins. It is preferable that the other resin is derived from plants from the viewpoint of reducing environmental load.
Examples of polyethylene resins include polyethylene resins such as linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE), and ethylene-vinyl acetate copolymers. , ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, and the like.
Examples of the polypropylene resin include propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, metallocene catalyst polypropylene, and the like.

Examples of resins other than the polyolefin resins mentioned above include ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, and ethylene-methyl methacrylate copolymer (EMMA). Ethylene copolymers such as ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); Ionomers of acrylic acid copolymers, ionomers of ethylene-methacrylic acid copolymers, etc. can be used.

In addition, polyester resins include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalene dicarboxylic acid as dicarboxylic acid components that are constituent monomers of polyester, and include polyethylene terephthalate (PET), polyethylene naphthalate, etc. (PEN) etc. are known. Further, there is no particular restriction on the diol component which is the other constituent monomer of these aromatic polyester resins. Usually, aliphatic diols such as ethylene glycol and 1,4-butanediol are often used, but in order to reduce crystallinity without lowering Tg, aliphatic diols such as cyclohexanedimethanol are used. Aromatic aliphatic polyester resins (PETG) are also commonly used.

When using the above-mentioned other resins, the amount thereof is preferably 10% by mass or less, more preferably 5% by mass or less in the resin component contained in the heat seal layer (A).

[Flowability modifier]
The heat-sealing layer (A) of the present invention contains a fluidity modifier which is a polyester having a carboxyl group at at least one end. The fluidity modifier has a function of increasing the fluidity of the mixture of the biodegradable polyester resin and inorganic filler. The heat seal layer (A) can be processed into a film even if it is a biodegradable polyester resin composition containing a large amount of inorganic filler by using the fluidity modifier. As a result, the heat seal layer (A) becomes easily openable due to cohesive failure.

The biodegradable polyester resin used in the present invention is generally highly polar and tends to have a high viscosity due to entanglement of molecular chains. When a polyester having a carboxyl group at at least one end is added as a fluidity modifier to the biodegradable polyester resin, the carboxyl group contained in the fluidity modifier will be adsorbed to the inorganic filler, and at the same time It is thought that the main chain of the fluidity modifier, which has a polarity close to that of the biodegradable polyester, ensures compatibility with the biodegradable resin. Further, the fluidity modifier is considered to have the effect of lowering the viscosity because it disentangles the molecular chains of the biodegradable polyester. It is presumed that this increases the fluidity of the biodegradable polyester resin containing the inorganic filler, making it possible to add a large amount of the inorganic filler.

The fluidity modifier is a polyester having a carboxyl group at at least one end, and preferably contains a repeating unit represented by the following general formula (A) and a repeating unit represented by the following general formula (G). or a polyester having a repeating unit represented by the following general formula (L), a repeating unit represented by the following general formula (A), and a repeating unit represented by the following general formula (G) It is.

（上記一般式（Ａ）、（Ｇ）及び（Ｌ）中、Ａは、炭素原子数２～１２の脂肪族二塩基酸残基又は炭素原子数６～１５の芳香族二塩基酸残基であり、Ｇは、炭素原子数２～９の脂肪族ジオール残基であり、Ｌは、炭素原子数２～１８のヒドロキシカルボン酸残基である。）

(In the above general formulas (A), (G) and (L), A is an aliphatic dibasic acid residue having 2 to 12 carbon atoms or an aromatic dibasic acid residue having 6 to 15 carbon atoms. (G is an aliphatic diol residue having 2 to 9 carbon atoms, and L is a hydroxycarboxylic acid residue having 2 to 18 carbon atoms.)

The polymerization type of the fluidity modifier is not particularly limited, and may be a random copolymer containing the above repeating unit or a block copolymer containing the above repeating unit.

The fluidity modifier is more preferably a polyester represented by the following general formula (1) and/or a polyester represented by the following general formula (2).

（上記一般式（１）及び（２）中、Ａ１、Ａ２及びＡ３は、それぞれ独立に、炭素原子数２～１２の脂肪族二塩基酸残基又は炭素原子数６～１５の芳香族二塩基酸残基であり、Ｇ１及びＧ２は、それぞれ独立に、炭素原子数２～９の脂肪族ジオール残基であり、ｎは、繰り返し数を表し、０～２０の範囲の整数である。
ただし、括弧で括られた繰り返し単位毎にＡ１及びＧ１はそれぞれ同じでもよく、異なっていてもよい。）

(In the above general formulas (1) and (2), A1, A2 and A3 are each independently an aliphatic dibasic acid residue having 2 to 12 carbon atoms or an aromatic dibasic acid residue having 6 to 15 carbon atoms. G1 and G2 are each independently an aliphatic diol residue having 2 to 9 carbon atoms, and n represents the number of repeats and is an integer in the range of 0 to 20.
However, A1 and G1 for each repeating unit enclosed in parentheses may be the same or different. )

Note that the "dibasic acid residue" is an organic group obtained by removing a basic acid functional group from a dibasic acid.
For example, when the dibasic acid residue is a dicarboxylic acid residue, the dicarboxylic acid residue refers to the remaining organic group of the dicarboxylic acid excluding the carboxyl group.
Regarding the number of carbon atoms in the dicarboxylic acid residue, carbon atoms in the carboxyl group are not included.
Furthermore, the term "diol residue" refers to the organic group remaining after removing the hydroxyl group from the diol.
Furthermore, the term "hydroxycarboxylic acid residue" refers to the organic group remaining after removing the hydroxyl group and carboxyl group from the hydroxycarboxylic acid.
Regarding the number of carbon atoms in the hydroxycarboxylic acid residue, carbon atoms in the carboxyl group are not included.

The aliphatic dibasic acid residues having 2 to 12 carbon atoms as A, A1, A2 and A3 may contain an alicyclic structure and/or an ether bond (-O-).
The aliphatic dicarboxylic acid residues having 2 to 12 carbon atoms as A, A1, A2, and A3 are preferably aliphatic dicarboxylic acid residues having 2 to 12 carbon atoms; Examples of aliphatic dicarboxylic acid residues include succinic acid residue, adipic acid residue, maleic acid residue, pimelic acid residue, suberic acid residue, azelaic acid residue, sebacic acid residue, cyclohexanedicarboxylic acid residue, Examples include dodecanedicarboxylic acid residues and hexahydrophthalic acid residues.

The aliphatic dibasic acid residues having 2 to 12 carbon atoms as A, A1, A2 and A3 are preferably aliphatic dicarboxylic acid residues having 2 to 10 carbon atoms, more preferably succinic acid residues, These include sebacic acid residues, maleic acid residues, and adipic acid residues, and more preferably sebacic acid residues, maleic acid residues, and adipic acid residues.

The aromatic dibasic acid residues having 6 to 15 carbon atoms as A, A1, A2, and A3 are preferably aromatic dicarboxylic acid residues having 6 to 15 carbon atoms, such as phthalic acid residues. etc.

A, A1, A2 and A3 are preferably aliphatic dibasic acid residues having 2 to 12 carbon atoms, more preferably aliphatic dicarboxylic acid residues having 2 to 12 carbon atoms, even more preferably It is an aliphatic dicarboxylic acid residue having 2 to 10 carbon atoms.

Examples of aliphatic diol residues having 2 to 9 carbon atoms for G, G1 and G2 include ethylene glycol residues, 1,2-propylene glycol residues, 1,3-propylene glycol residues, and 1,2-butanediol. residue, 1,3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1 , 3-propanediol (neopentyl glycol) residue, 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane) residue, 2-n-butyl-2-ethyl-1,3 -Propanediol (3,3-dimethylolheptane) residue, 3-methyl-1,5-pentanediol residue, 1,6-hexanediol residue, 2,2,4-trimethyl 1,3-pentanediol residue, 2-ethyl-1,3-hexanediol residue, 2-methyl-1,8-octanediol residue, 1,9-nonanediol residue, etc.

The aliphatic diol residues of G, G1 and G2 having 2 to 9 carbon atoms may contain an alicyclic structure and/or an ether bond (-O-).
Examples of the aliphatic diol residues having 2 to 9 carbon atoms containing an alicyclic structure include 1,3-cyclopentanediol residues, 1,2-cyclohexanediol residues, and 1,3-cyclohexanediol residues. , 1,4-cyclohexanediol residue, 1,2-cyclohexanedimethanol residue, 1,4-cyclohexanedimethanol residue, etc.
Examples of the aliphatic diol residues having 2 to 9 carbon atoms containing an ether bond include diethylene glycol residues, triethylene glycol residues, tetraethylene glycol residues, dipropylene glycol residues, tripropylene glycol residues, etc. can be mentioned.

The aliphatic diol residues having 2 to 9 carbon atoms in G, G1 and G2 are preferably aliphatic diol residues having 3 to 8 carbon atoms, more preferably ethylene glycol residues, diethylene glycol residues, 1 , 2-propylene glycol residue, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-butanediol or 1,3-butanediol residue.

Hydroxycarboxylic acid residues having 2 to 18 carbon atoms for L include propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, caprylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, and pentadecyl acid. Examples include residues of hydroxycarboxylic acids in which one hydroxyl group is substituted in the aliphatic chain of aliphatic carboxylic acids having 3 to 19 carbon atoms such as palmitic acid, margaric acid, and stearic acid; specific examples include lactic acid residues. , 9-hydroxystearic acid residue, 12-hydroxystearic acid residue, 6-hydroxycaproic acid residue, 3-hydroxybutyric acid residue, 3-hydroxyvaleric acid residue, 3-hydroxyhexanoic acid residue, 3- Examples include hydroxypropionic acid residue, 4-hydroxybutyric acid residue, 5-hydroxyvaleric acid residue, and the like.

The hydroxycarboxylic acid residue having 2 to 18 carbon atoms in L is preferably an aliphatic hydroxycarboxylic acid residue having 4 to 18 carbon atoms, more preferably a 12-hydroxystearic acid residue.

The repeating number of n is an integer in the range of 0 to 20, preferably an integer in the range of 1 to 20, more preferably an integer in the range of 5 to 20.

The number average molecular weight (Mn) of the polyester is, for example, in the range of 100 to 5,000, preferably in the range of 300 to 4,000, more preferably in the range of 500 to 3,000, and It is preferably in the range of 800 to 2,400.
The above number average molecular weight (Mn) is a value converted to polystyrene based on gel permeation chromatography (GPC) measurement, and is measured by the method described in Examples.

The lower limit of the acid value of the fluidity modifier is not particularly limited, but is preferably 20 or more, more preferably 25 or more. The upper limit of the acid value is also not particularly limited, but is preferably 400 or less, more preferably 200 or less, 150 or less, 120 or less, 100 or less, and 95 or less.
The above acid value is confirmed by the method described in Examples.

The hydroxyl value of the fluidity modifier is also not particularly limited, but may be, for example, 0 or more, preferably in the range of 10 to 200, more preferably in the range of 20 to 150, even more preferably 50 to 120. is within the range of
The above hydroxyl value is confirmed by the method described in Examples.

The properties of the fluidity modifier vary depending on the number average molecular weight, composition, etc., but are usually liquid, solid, paste, etc. at room temperature.

The content of the fluidity modifier is not particularly limited, but for example, the fluidity modifier is in the range of 5 to 100 parts by mass, preferably 5 to 50 parts by mass, per 100 parts by mass of the inorganic filler. The amount is preferably in the range of 5 to 30 parts by mass.

The fluidity modifier described above is obtained using a reaction raw material containing an aliphatic dibasic acid and/or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid.
Here, the reaction raw material means a raw material constituting the fluidity modifier, and does not include a solvent or a catalyst that does not constitute polyester.
Moreover, "any hydroxycarboxylic acid" means that hydroxycarboxylic acid may or may not be used.
The method for producing the fluidity modifier is not particularly limited, and it can be produced by a known method, and can be produced by the production method described below.

The reaction raw materials for the fluidity modifier may include an aliphatic dibasic acid and/or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid, and may also contain other raw materials.
The reaction raw material of the fluidity modifier is preferably 90% by mass or more of aliphatic dibasic acid and/or aromatic dibasic acid, aliphatic diol, and any hydroxycarboxylic acid based on the total amount of the reaction raw material. More preferably, it consists only of an aliphatic dibasic acid and/or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid.

The aliphatic dibasic acid used in the production of the fluidity modifier is an aliphatic dibasic acid corresponding to the aliphatic dibasic acid residues of A, A1, A2 and A3 having 2 to 12 carbon atoms, The aliphatic dibasic acids used may be used alone or in combination of two or more.
The aromatic dibasic acid used in the production of the fluidity modifier is an aromatic dibasic acid corresponding to the aromatic dibasic acid residues of A, A1, A2 and A3 having 6 to 15 carbon atoms, The aromatic dibasic acids used may be used alone or in combination of two or more.
The aliphatic diol used in the production of the fluidity modifier is an aliphatic diol corresponding to the aliphatic diol residues having 2 to 9 carbon atoms in G, G1, and G2, and one type of aliphatic diol is used. They may be used alone or in combination of two or more.
The hydroxycarboxylic acid used in the production of the fluidity modifier is a hydroxycarboxylic acid corresponding to the hydroxycarboxylic acid residue having 2 to 18 carbon atoms in L, and the hydroxycarboxylic acid used may be used alone. or two or more types may be used in combination.
The reaction raw materials used also include derivatives of the above-mentioned esters, the above-mentioned acid chlorides, the above-mentioned acid anhydrides, and the like.
For example, hydroxycarboxylic acids also include compounds having a lactone structure such as ε-caprolactone.

The above-mentioned fluidity modifier uses an aliphatic dibasic acid and/or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid constituting each residue of the fluidity modifier as a reaction raw material. It can be produced by reacting under conditions in which the equivalent weight of carboxyl groups contained is greater than the equivalent weight of hydroxyl groups.
The fluidity modifier contains an aliphatic dibasic acid and/or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid constituting each residue of the fluidity modifier as a reaction raw material. After obtaining a polyester having a hydroxyl group at the end of the main chain by reacting under conditions such that the equivalent of the hydroxyl group contained is greater than the equivalent of the carboxyl group, the resulting polyester is further treated with an aliphatic dibasic acid and/or an aromatic acid. It can also be produced by reacting dibasic acids.

The fluidity modifier preferably contains one or more aliphatic dibasic acids selected from the group consisting of succinic acid, sebacic acid, azelaic acid, maleic acid, and adipic acid residues, and ethylene glycol, diethylene glycol, , 2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentane Diol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 3-methyl-1 , 5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8 - A polyester whose raw material is reacted with one or more aliphatic diols selected from octanediol and 1,9-nonanediol.

The fluidity modifier is more preferably one or more aliphatic dibasic acids selected from the group consisting of sebacic acid, maleic acid, and adipic acid, and ethylene glycol, diethylene glycol, 1,2-propanediol, , 3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-butanediol and 1,3-butanediol. This is polyester used as a reaction raw material.
Regarding these reaction raw materials, those derived from biomass can be used. Thereby, the biomass degree of the obtained polyester can be improved.
From the viewpoint of sustainability, it is preferable to use polyester with a high degree of biomass as the biodegradable resin.

In the production of the fluidity modifier, the reaction of the reaction raw materials is carried out in the presence of an esterification catalyst if necessary, for example, at a temperature range of 180 to 250°C for 10 to 25 hours. Good.
Note that conditions such as temperature and time for the esterification reaction are not particularly limited and may be set as appropriate.

Examples of the esterification catalyst include titanium catalysts such as tetraisopropyl titanate and tetrabutyl titanate; zinc catalysts such as zinc acetate; tin catalysts such as dibutyltin oxide; and organic sulfonic acid catalysts such as p-toluenesulfonic acid. Examples include catalysts.

The amount of the esterification catalyst to be used may be determined as appropriate, but it is usually used in the range of 0.001 to 0.1 part by mass based on 100 parts by mass of the total amount of reaction raw materials.

[Inorganic filler]
The heat seal layer (A) of the present invention contains an inorganic filler. Inorganic fillers are not particularly limited, and include, for example, calcium carbonate, talc, silica, alumina, clay, antimony oxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, calcium silicate, magnesium oxide, potassium titanate, barium titanate, Examples include titanium oxide, calcium oxide, magnesium oxide, manganese dioxide, boron nitride, aluminum nitride, and the like.
The above inorganic fillers may be used alone or in combination of two or more.

The inorganic filler is preferably one or more selected from the group consisting of calcium carbonate, silica, alumina, aluminum hydroxide, barium titanate, talc, boron nitride, and aluminum nitride, more preferably calcium carbonate, alumina, One or more types selected from the group consisting of aluminum hydroxide and talc.

The particle size, fiber length, fiber diameter, and other shapes of the inorganic filler are not particularly limited, and may be adjusted as appropriate depending on the intended use. Furthermore, the surface treatment state of the inorganic filler is not particularly limited, and the surface may be modified with, for example, saturated fatty acids depending on the intended use.

The content of the inorganic filler is, for example, in the range of 1 to 200 parts by mass, 1 to 100 parts by mass, 5 to 100 parts by mass, based on 100 parts by mass of the biodegradable polyester resin in the heat seal layer (A). It may be in the range of 70 parts by weight, in the range of 10 to 60 parts by weight, or in the range of 15 to 55 parts by weight.
Further, the inorganic filler is contained in the heat seal layer (A) in an amount of 10% by mass or more, preferably 10 to 70% by mass, more preferably 15 to 60% by mass, and 20 to 50% by mass. It is more preferable that the content is % by mass.

Furthermore, the ratio of the inorganic filler to the fluidity modifier is in the range of inorganic filler/fluidity modifier = 1 to 20. When the ratio is within this range, the increase in viscosity caused by adding a large amount of inorganic filler can be suppressed to a range that allows film formation with the fluidity modifier. Further, the range is preferably 2 to 20, more preferably 3 to 20, since film forming properties are improved.

(Other additives)
Various additives may be added to the heat-sealing layer (A) as long as they do not impair the effects of the present invention.
Examples of such additives include antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, lubricants, nucleating agents, pigments, and biodegradability promoting additives.
In addition, especially when using a resin other than the above-mentioned biodegradable resin, it is preferable to use a biodegradability-promoting additive so that the film exhibits biodegradability.
Examples of the biodegradability-promoting additive include an additive containing an enzyme, an additive containing a microorganism, an additive containing a microorganism attractant, and the like.

(Resin layer (B))
The biodegradable film of the present invention may be a multilayer film including a resin layer (B) directly laminated with the heat seal layer (A).
As the resin layer (B), it is preferable to use the biodegradable polyester resins listed for the heat seal layer (A), and the resin layer contains the above polylactic acid resin and the above polybutylene succinate resin as the main resin components. It is more preferable to do so, and may contain the other biodegradable polyester resins mentioned above, or may contain the other biodegradable resins mentioned above.
By using the resin layer (B), it is possible to suitably laminate it with the heat seal layer (A) while using an environmentally friendly material, and it is possible to realize good releasability of the resulting multilayer film.
In the resin layer (B), the biodegradable polyester resin may be used alone or in combination.

As the polylactic acid resin, the same ones as the polylactic acid resin in the heat-sealing layer (A) can be used, and the preferable types, preferable ranges of melt flow rate and density, etc. are also the same.

As the polybutylene succinate resin, the same ones as the polybutylene succinate resin in the heat seal layer (A) can be used, and the preferable types, melt flow rate, preferable range of density, etc. are also the same.

As the other biodegradable polyester resin, the same ones as the other biodegradable polyester resin in the heat seal layer (A) can be used.
As the other biodegradable resin, the same one as the other biodegradable resin in the heat seal layer (A) can be used.

The total content of the biodegradable polyester resin in the resin layer (B) is preferably 80% by mass or more, and 90% by mass of the resin components contained in the resin layer (B). It is more preferable that it is the above, and it is also preferable that it consists essentially only of these resins.

The resin layer (B) may contain other resins other than those mentioned above, and as the other resins, those exemplified as other resins in the heat seal layer (A) can be used. The content in the resin layer (B) is preferably less than 10% by mass, more preferably less than 5% by mass.

Various additives may be added to the resin layer (B) within a range that does not impair the effects of the present invention.
Examples of such additives include antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, lubricants, nucleating agents, pigments, and biodegradability promoting additives.
In addition, especially when using a resin other than the above-mentioned biodegradable resin, it is preferable to use a biodegradability-promoting additive so that the film exhibits biodegradability.
Examples of the biodegradability-promoting additive include an additive containing an enzyme, an additive containing a microorganism, an additive containing a microorganism attractant, and the like.

[Biodegradable film]
The biodegradable film of the present invention is a biodegradable film having the heat-sealing layer (A), and is a multilayer film in which the heat-sealing layer (A) and the resin layer (B) are directly laminated. is preferred.
By having the above structure, the biodegradable film of the present invention can achieve suitable heat-sealability and easy-opening properties for packaging materials made of various materials including environmentally friendly materials.
Moreover, since each layer can be composed mainly of biodegradable resin, the biodegradable film itself has high environmental friendliness.
Furthermore, since easy opening can be achieved through cohesive failure of the heat-sealing layer (A), stable opening strength can be exhibited even if there is fluctuation in the production of the biodegradable film of the present invention or fluctuation in heat-sealing temperature. can. In addition, a lid material with excellent foreign substance sealing properties can be obtained. Furthermore, since it is possible to achieve easy opening due to cohesive failure, the peeled area turns white, which becomes proof that the package has been opened and prevents tampering.

In the biodegradable film of the present invention, the heat seal layer (A) constitutes one surface layer of the film.
The surface layer other than the heat seal layer (A) may be a resin layer (B), but the thickness of the heat seal layer may be suitably adjusted to obtain stability during manufacturing and suitable film formability. It is also preferable to laminate another resin layer (C) constituting the surface layer.

As the resin layer (C), the same resin layer as the resin layer (B) can be preferably used, and it may have the same resin composition as the resin layer (B) or a different resin composition.
It is preferable to use the same resin formulation because manufacturing is easy.
Furthermore, by using different resin formulations, it becomes easy to adjust the physical properties of the multilayer film.

Furthermore, another resin layer (D) may be provided between the resin layer (C) and the resin layer (B), and in particular, in the present invention, the proportion of layers other than the heat seal layer (A) in the total thickness Therefore, in order to facilitate thickness adjustment with the heat-sealing layer (A) when using a coextrusion method, it is preferable to have a four-layer structure because it is easy to obtain a multilayer film with excellent homogeneity.
Even when a resin layer (D) is provided, the resin layer (D) may be a layer using a resin or composition preferable to the resin layer (B) or the resin layer (C). The resin composition may be the same mixture as the resin layer (B) and the resin layer (C), or may be a mixture having different resin compositions, MFRs, and densities.

Examples of specific preferred layer configurations include heat seal layer (A)/resin layer (B), heat seal layer (A)/resin layer (B)/resin layer (C), and heat seal layer (A)/resin layer (C). Examples include resin layer (B)/resin layer (C), heat seal layer (A)/resin layer (B)/resin layer (D)/resin layer (C), and the like.

The thickness (total thickness) of the biodegradable film of the present invention is preferably 20 to 70 μm, particularly in the range of 20 to 50 μm, from the viewpoint of reducing the weight of the packaging material and ease of opening. It is more preferable that there be.

The thickness of the heat seal layer (A) is preferably in the range of 8 to 90% of the total thickness of the film, more preferably in the range of 10 to 70%.
When the biodegradable film has a three-layer structure of heat seal layer (A)/resin layer (B)/resin layer (C), the thickness of the resin layer (B) is 10 to 82% of the total thickness of the film. The thickness of the resin layer (C) is preferably 10 to 40%, the thickness of the resin layer (B) is 20 to 60%, and the thickness of the resin layer (C) is 10 to 30%. is more preferable.
When the biodegradable film has a four-layer structure of heat seal layer (A)/resin layer (B)/resin layer (D)/resin layer (C), the thickness of the resin layer (B) with respect to the total thickness of the film. The thickness of the resin layer (C) is preferably 20 to 60%, the thickness of the resin layer (D) is 10 to 35%, and the thickness of the resin layer (B) is 10 to 30%. More preferably, the thickness of the resin layer (C) is 25 to 55%, and the thickness of the resin layer (D) is 10 to 30%.

As for the specific thickness, the heat seal layer (A) preferably has a thickness of 2 to 45 μm, more preferably 3 to 35 μm.

The biodegradable film of the present invention can realize excellent environmental friendliness because each layer can be composed of a biodegradable resin.
In particular, since it has excellent environmental friendliness, the total amount of biodegradable resin in the resin component of the biodegradable film is preferably 80% by mass or more, more preferably 90% by mass or more, and Particularly preferable is one in which the component consists essentially only of these resins because the biodegradability of the film itself can be ensured.
In addition, by using polylactic acid resin and/or polybutylene succinate resin as the main resin component of the resin layer (B), resin layer (C), and resin layer (D), biodegradability and film It is preferable because it is easy to achieve both characteristics.
Furthermore, when a plant-derived biomass resin is used as the resin component of each layer, environmental friendliness can be imparted at a relatively low cost.

(Method for manufacturing biodegradable film)
The method for producing the biodegradable film of the present invention is not particularly limited, but for example, each resin or resin mixture used for each layer is heated and melted in separate extruders, and coextrusion multilayer die method, feed block method, etc. Heat-sealing layer (A) only, heat-sealing layer (A)/resin layer (B), heat-sealing layer (A)/resin layer (B)/resin layer (C), or heat-sealing in a molten state by the method of Examples include a coextrusion method in which layer (A)/resin layer (B)/resin layer (D)/resin layer (C) are laminated and then formed into a film by inflation, T-die chill roll method, or the like.
The coextrusion method is preferable because it allows the ratio of the thickness of each layer to be adjusted relatively freely, and a multilayer film with excellent hygiene and cost performance can be obtained. Furthermore, the biodegradable film of the present invention contains a fluidity modifier and has excellent processability.
When resins with a large difference in melting point and Tg are laminated, the appearance of the film may deteriorate during coextrusion processing, or it may become difficult to form a uniform layer structure. In order to suppress such deterioration, the T-die chill roll method, which allows melt extrusion to be performed at a relatively high temperature, is preferred.
Alternatively, a single-layer film consisting only of the heat-sealing layer (A) may be extruded, or a resin film corresponding to the resin layer (B) may be laminated on one surface of the single-layer film by dry lamination or the like. It may also be a multilayer film.

In addition, as a resin mixture used for the heat-sealing layer (A), a masterbatch is prepared in which the blending ratio of the above-mentioned inorganic filler and the above-mentioned fluidity modifier to the resin is increased, and this masterbatch is mixed with biodegradable polyester. The resin mixture may be diluted with a system resin to be used in the heat seal layer of the present invention. The blending ratio of each component in the masterbatch is preferably 20 to 80% by mass of inorganic filler, 1 to 20% by mass of fluidity modifier, and 20 to 79% by mass of resin.

Furthermore, as a resin mixture used for the heat-sealing layer (A), a masterbatch with a high blending ratio of the fluidity modifier to the resin is prepared, and an inorganic filler is kneaded into this masterbatch. It may also be used as a resin mixture for the heat seal layer. The blending ratio of each component in the masterbatch is preferably 1 to 20% by mass of the fluidity modifier and 80 to 99% by mass of the resin.

What is the heat-sealing layer (A)? When printing or laminating on the other surface, the heat-sealing layer (A) is a layer that is added to the other surface to improve adhesion with printing ink or adhesive. It is preferable to perform treatment.
Examples of such surface treatments include surface oxidation treatments such as corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, ozone/ultraviolet treatment, and surface roughening treatments such as sandblasting. Corona treatment is preferred.

[Laminate film]
Since the biodegradable film of the present invention can be suitably used as a lid material for various packaging containers, it is also preferable to laminate a laminate base material on the other surface of the heat seal layer (A) to form a laminate film.
The laminating base material is not particularly limited, but it is generally a stretched base film because it ensures strength without breaking, ensures heat resistance during heat sealing, and improves the design of printing. It is preferable.
As the stretched base film, biaxially stretched polyester film, biaxially stretched nylon film, biaxially stretched polypropylene film, etc. can be used. Further, it is preferable to laminate a biodegradable base film such as a stretched polylactic acid film, paper, or cellophane, because the biodegradability of the entire laminate film can be ensured. Note that the base film may be subjected to easy tearing treatment or antistatic treatment, depending on necessity.

The method for producing the laminate film is not particularly limited, but for example, a laminate base material is placed on the heat seal layer (A), resin layer (B), or resin layer (C) that forms the surface of the biodegradable film. An example is a method of laminating.
Examples of methods for laminating the biodegradable film of the present invention with a laminate base material include dry lamination, thermal lamination, multilayer extrusion coating, and the like, and among these, dry lamination is more preferred.
Further, examples of the adhesive used when laminating the biodegradable film and the laminate base material in the dry lamination method include polyether-polyurethane adhesives, polyester-polyurethane adhesives, and the like.
Furthermore, it is preferable to subject the surface of the biodegradable film of the present invention to a corona discharge treatment before laminating the biodegradable film of the present invention and the base material, since this improves the adhesion to the base material.

[Package]
The biodegradable film and laminate film of the present invention can be suitably used as various packaging materials.
In particular, it can be suitably used for dairy products, yogurt, jelly, tofu, pickle containers, kimchi containers, sweets containers, rice containers, instant noodle containers, etc., and the lid material uses a packaging container with an opening as an adherend. It can be particularly suitably used as

The packaging container with an opening that serves as an adherend is preferably biodegradable, and may be made of polylactic acid polymer, polybutylene succinate polymer, paper/polylactic acid polymer, paper/polybutylene succinate polymer, etc. Examples include various packaging containers using biodegradable polyester resins such as nate-based polymers and polyethylene terephthalate. In particular, it is preferable to use a packaging container in which a polybutylene succinate polymer is used for the adhesion surface.
The biodegradable film of the present invention can achieve suitable heat-sealability and easy-opening properties for packaging containers made of these various materials.

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

<Synthesis of fluidity modifier>
(Synthesis example 1)
In a 2-liter four-necked flask equipped with a thermometer, stirrer, and reflux condenser, add 876.8 g of adipic acid, 612.7 g of 1,3-butanediol, 78.7 g of neopentyl glycol, 0.047 g of tetraisopropyl titanate was charged as an esterification catalyst, and the temperature was raised stepwise to 220° C. while stirring under a nitrogen stream to carry out a condensation reaction for a total of 14 hours. For 250 g of the obtained reaction product, 13.1 g of maleic anhydride was further charged, the reaction was completed at 120°C, and polyester fluidity modifier A (acid value: 29, hydroxyl value: 73, number average molecular weight: 1,290) was obtained.

(Synthesis example 2)
In a four-neck flask with an internal volume of 0.5 liters equipped with a thermometer, stirrer, and reflux condenser, 200 g of GI-1000 (manufactured by Nippon Soda Co., Ltd., polybutadiene with hydrogenated hydroxyl groups at both ends) and maleic anhydride were added. A polyolefin fluidity modifier B (acid value: 30, number average molecular weight: 2,600) was obtained by charging 10.5 g and reacting at 120° C. for 3 hours.

(Synthesis example 3)
In a four-neck flask with an internal volume of 0.5 liters equipped with a thermometer, stirrer, and reflux condenser, 200 g of GI-3000 (manufactured by Nippon Soda Co., Ltd., polybutadiene with hydrogenated hydroxyl groups at both ends) and maleic anhydride were added. A polyolefin fluidity modifier C (acid value: 30, number average molecular weight: 5,920) was obtained by charging 10.5 g and reacting at 120° C. for 3 hours.

(Measurement of number average molecular weight)
In the Examples of the present application, the number average molecular weight of the fluidity modifier is a polystyrene equivalent value based on GPC measurement, and the measurement conditions are as follows.
[GPC measurement conditions]
Measuring device: High-speed GPC device “HLC-8320GPC” manufactured by Tosoh Corporation
Column: "TSK GURDCOLUMN SuperHZ-L" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation + “TSK gel SuperHZ-2000” manufactured by Tosoh Corporation
Detector: RI (differential refractometer)
Data processing: “EcoSEC Data Analysis version 1.07” manufactured by Tosoh Corporation
Column temperature: 40℃
Developing solvent: Tetrahydrofuran Flow rate: 0.35 mL/min Measurement sample: 7.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran, and the resulting solution was filtered with a microfilter to obtain the measurement sample.
Sample injection volume: 20μl
Standard sample: The following monodisperse polystyrene with a known molecular weight was used in accordance with the measurement manual for the above-mentioned "HLC-8320GPC".

(Monodisperse polystyrene)
"A-300" manufactured by Tosoh Corporation
"A-500" manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation
"F-40" manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
"F-128" manufactured by Tosoh Corporation
"F-288" manufactured by Tosoh Corporation

In the Examples of the present application, the values of acid value and hydroxyl value are values evaluated by the following method.
Acid value: Measured by a method according to JIS K0070-1992.
Hydroxyl value: Measured by a method according to JIS K0070-1992.

<Evaluation of compatibility>
100 parts by mass of polybutylene succinate (PTTMCC Biochem "Bio-PBS FZ91PM") and 5 parts by mass of a fluidity modifier were kneaded with a mixer at 120°C for 10 minutes, and then pressed into a 1 mm thick press sheet using a hot press machine. . After the obtained sheet was left at room temperature for 10 days, the surface condition of the sheet was checked by touch. If the surface is not sticky and bleeding of the fluidity modifier is not observed, the compatibility is rated as ◎, and if the surface is sticky and bleeding of the fluidity modifier is observed, the compatibility is rated as ×.

<Preparation of sample for disintegration test>
(Sample 1)
As the resin components forming each layer of the heat seal layer (A) and the resin layer (B), resin mixtures forming each layer were prepared at the blending ratios shown in Table 1 below. The resin mixtures forming each layer are melted and supplied to two extruders respectively, and the thickness of each layer of the multilayer film formed by the heat seal layer (A)/resin layer (B) is 3 μm/27 μm. As shown, the coextrusion multilayer film production apparatus using a T-die chill roll method having a feed block (feed block and T die temperature: 200°C) is fed to coextrude, and the film is cooled with a water-cooled metal cooling roll at 40°C. A biodegradable film with a total thickness of 30 μm was molded. The film was cut out to a size of 3 cm x 3 cm to obtain Sample 1.

(Samples 2 and 3)
Samples 2 and 3 were prepared in the same manner as Sample 1 except that the blending ratio of each layer and the layer thickness were changed as shown in Table 1.

(Sample 4)
Polypan Mat 7283-2 (manufactured by DIC Corporation, low-density polyethylene-based talc masterbatch) was melted and supplied to an extruder to form a 30 μm film. The obtained sheet was cut out into a size of 3 cm x 3 cm to obtain Sample 4.

<Evaluation of disintegration>
A glass bottle was filled with soil (moisture 30 wt%) collected from a field in Ichihara City, Chiba Prefecture, and a test piece was buried in this soil. After closing the lid of the glass bottle and leaving it in a constant temperature bath at 60°C for 4 weeks, the test piece was collected. A test piece whose decomposition progressed to such an extent that visual recovery was difficult was judged as ◎, and a test piece with no change in appearance or weight was judged to have a disintegrability of ×.

The ingredients in Table 1 are as follows.
PBS: polybutylene succinate copolymer (PTTMCC Biochem "FZ91PB", density: 1.26 g/cm ³ , melting point 115°C, MFR: 5g/10 min (190°C, 21.18N))
Fluidity modifier A: Fluidity modifier A of Synthesis Example 1
Talc (hydrated magnesium silicate: 3MgO・4SiO ₂・H ₂ O): Micron White 5000A (manufactured by Hayashi Kasei Co., Ltd.)

As is clear from the above results, Samples 1 to 3, which are resin mixtures used in the heat seal layer of the present invention, had good biodegradability. On the other hand, Sample 4, which does not have biodegradability, did not biodegrade.

<Manufacture of biodegradable film>
(Example 1)
As the resin components forming each layer of the heat seal layer (A) and the resin layer (B), resin mixtures forming each layer were prepared at the blending ratios shown in Table 1 below. The resin mixture forming each layer is melted and supplied to two extruders, and the thickness of each layer of the multilayer film formed by the heat seal layer (A)/resin layer (B) is 7.5 μm/22 .5 μm, each is supplied to a coextrusion multilayer film manufacturing apparatus using a T-die/chill roll method having a feed block (feed block and T-die temperature: 200°C), and coextruded to a water-cooled metal chill roll at 40°C. The biodegradable film of Example 1 having a total thickness of 30 μm was molded.

(Examples 2 to 4)
The biodegradable films of Examples 2 to 4 were molded in the same manner as in Example 1, except that the blending ratio of each layer and the layer thickness were changed as shown in Table 3.

(Comparative Examples 1 to 3)
Biodegradable films of Comparative Examples 1 to 3 were molded in the same manner as in Example 1, except that the blending ratio of each layer and the layer thickness were changed as shown in Table 4.

The raw materials used are as follows.
PBS: polybutylene succinate copolymer (PTTMCC Biochem "FZ91PB", density: 1.26 g/cm ³ , melting point 115°C, MFR: 5g/10 min (190°C, 21.18N))
PLA: Polylactic acid resin (“3001D” manufactured by Nature Works, density: 1.24 g/cm ³ (ASTM D792), MFR: 22 g/10 minutes (210°C, 1.26 kg)
Talc (hydrous magnesium silicate: 3MgO・4SiO ₂・H ₂ O): Micron White 5000A (manufactured by Hayashi Kasei Co., Ltd.)
Fluidity modifiers A to C: Fluidity modifiers A to C of Synthesis Examples 1 to 3

The films obtained in the above Examples and Comparative Examples were evaluated as follows.
The results obtained are shown in Tables 4 and 5.

(Preparation of laminate film)
A cellophane film (thickness: 20 μm) was attached to the base layer (B) side surface of the biodegradable film obtained in the above Examples and Comparative Examples or the single layer film surface by dry lamination to obtain a laminate film. . At this time, a two-component curing adhesive (polyester adhesive "LX500" and curing agent "KR-90") manufactured by DIC Corporation was used as the adhesive for dry lamination.

(Evaluation of film formability)
During the production of the films prepared in Examples and Comparative Examples, the occurrence of gel and holes was confirmed.
○: A film can be formed, and the number of holes is 1/ ^m2 or less.
△: Film could be formed, but 2 holes/m2 ^or more were formed.
×: Film cannot be formed.

(Rigidity evaluation)
The 1% secant modulus of the films obtained in the Examples and Comparative Examples described above was determined as the rigidity (hardness), and was evaluated based on the following criteria. The 1% secant modulus was measured using a film cut out as a test piece with a length of 300 mm x width of 25.4 mm (marked line interval 200 mm) so that the longitudinal direction was the film flow direction (vertical direction), and ASTM D- 882 at a tensile speed of 20 mm/min.
○: 350 MPa or more.
×: Less than 350 MPa.

(Impact resistance evaluation)
Test pieces were prepared in which the films obtained in Examples and Comparative Examples were allowed to stand for 4 hours in a thermostatic chamber adjusted to below 0°C. For each test piece, the impact strength was measured by the film impact method using a BU-302 film impact tester manufactured by Tester Sangyo, with a 1.5-inch head attached to the tip of a pendulum.
○: Impact strength is 0.10J or more ×: Impact strength is less than 0.10J

(Evaluation of blocking resistance)
A load of 400 g was applied to 10 film pieces cut into 10 cm square pieces from the films obtained in Examples and Comparative Examples and stored at 40° C. for one month. Thereafter, the strength of the attached films was measured by cutting out a 15 mm wide strip into a test piece, and using a tensile tester (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH. , 90° peeling was performed at a speed of 300 mm/min, and the blocking strength was measured.
○: Blocking strength is less than 100 g/15 mm.
×: Blocking strength is 100 g/15 mm or more.

(Evaluation of heat sealability (easy peelability) to PBS sheet)
The laminate film obtained in the above laminate film production and a PBS sheet (polybutylene succinate resin, thickness 100 μm) were heat-sealed at temperatures of 110 to 150°C in 10°C increments (0.2 MPa, 1 seconds). The seal sample was cut into 15 mm strips, used as test pieces, and tested at a speed of 300 mm/min using a tensile tester (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH. Peeling was performed at 180°, and the heat seal strength was measured and evaluated based on the following criteria.
◎: Heat seal strength at all temperatures is 5 N/15 mm or more and 20 N/15 mm or less.
○: Heat seal strength at all temperatures is 5 N/15 mm or more and 35 N/15 mm or less.
Δ: There are 1 to 2 temperatures at which the heat seal strength is less than 5 N/15 mm or more than 35 N/15 mm.
×: The heat seal strength is less than 5 N/15 mm, or there are 3 or more temperatures at which the film does not peel off on the sealing surface and the film breaks.

(Peeling marks)
The laminate film obtained in the above laminate film production and the PBS sheet (thickness 100 μm) were heat-sealed at 140° C. (0.2 MPa, 1 second). The seal sample was cut into 15 mm strips to be used as test pieces, and the test pieces were tested at a speed of 300 mm/min using a tensile tester (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH. Peeling was performed at 180°, and the appearance of peeling was evaluated based on the following criteria.
○: The force required for peeling is constant, smooth peeling is easy, and peeling marks are clear.
×: The force required for peeling is not constant, and peeling lacks smoothness. Or no peeling marks are seen.

(Evaluation of heat sealability (easy peelability) to PLA sheet)
The laminate film obtained in the above laminate film production and a PLA sheet (thickness: 300 μm) were heat-sealed at 120° C. and 150° C. (0.2 MPa, 1 second). The seal sample was cut into 15 mm strips to be used as test pieces, and the test pieces were tested at a speed of 300 mm/min using a tensile tester (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH. Peeling was performed at 180°, and the heat seal strength was measured and evaluated based on the following criteria.
◎: Heat seal strength at all temperatures is 5 N/15 mm or more and 20 N/15 mm or less.
○: Heat seal strength at all temperatures is 5 N/15 mm or more and 35 N/15 mm or less.
×: The heat seal strength is less than 5 N/15 mm or the sealing surface does not peel off, and the temperature at which the film breaks occurs is 1 level or higher.

(Evaluation of heat sealability (easy peelability) between surfaces)
The laminate films obtained in the production of the laminate film described above were stacked with their heat-sealing layer (A) sides on top of each other, and heat-sealed at 120°C and 150°C (0.2 MPa, 1 second). The seal sample was cut into 15 mm strips to be used as test pieces, and the test pieces were tested at a speed of 300 mm/min using a tensile tester (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH. Peeling was performed at 180°, and the heat seal strength was measured and evaluated based on the following criteria.
◎: Heat seal strength at all temperatures is 5 N/15 mm or more and 20 N/15 mm or less.
○: Heat seal strength at all temperatures is 5 N/15 mm or more and 35 N/15 mm or less.
×: The heat seal strength is less than 5 N/15 mm or the sealing surface does not peel off, and the temperature at which the film breaks occurs is 1 level or higher.

As is clear from the above Tables 4 and 5, the biodegradable films of the present invention of Examples 1 to 4 use biodegradable resins, and biodegradable polyester resins such as polybutylene succinate resin and polylactic acid. It exhibited stable and easy peelability over a wide range of heat-sealing temperatures, and had rigidity, film-forming properties, impact resistance, anti-blocking properties, etc. suitable for packaging applications. In addition, it is clear that the peeling was caused by cohesive failure because peeling marks remain firmly, and the seal strength and sealing performance are unlikely to deteriorate even if there are foreign substances. Furthermore, since the peeling marks make it visible that the package has been opened, unauthorized opening can be prevented.
On the other hand, the biodegradable film of Comparative Example 1 contained neither a fluidity modifier nor an inorganic filler, and therefore had poor peelability. The biodegradable film of Comparative Example 2 contained talc as an inorganic filler but did not contain a fluidity modifier, and therefore could not be formed. The biodegradable film of Comparative Example 3 contains an inorganic filler and a fluidity modifier, but the ratio is inorganic filler/fluidity modifier = 30, and the fluidity modifier is in proportion to the amount of inorganic filler. Due to insufficient amount, it was not possible to form a film. The biodegradable films of Comparative Examples 4 and 5 could not be formed because the fluidity modifier used was not a polyester having a carboxyl group at at least one end.

Claims (6)

Including a heat seal layer (A) containing a biodegradable polyester resin, a fluidity modifier, and an inorganic filler,
The heat seal layer (A) contains 10% by mass or more of the inorganic filler,
The fluidity modifier is a polyester having a carboxyl group at at least one end,
A biodegradable film, characterized in that the ratio of the inorganic filler to the fluidity modifier is in the range of inorganic filler/fluidity modifier = 1 to 20. The biodegradable film according to claim 1, wherein the content of biodegradable polyester resin in the resin component constituting the heat seal layer (A) is 80% by mass or more. The biodegradable film according to claim 1, which has easy openability due to cohesive failure in the heat seal layer (A) when applied to an adherend. A laminate film comprising the biodegradable film according to claims 1 to 3. The layer that adheres to the heat-sealing layer (A) of the adherend is composed of the biodegradable film according to any one of claims 1 to 3 and an adherend, and the layer that adheres to the heat seal layer (A) of the adherend has a polybutylene succinate resin as its main resin component. A package containing as. The package according to claim 5, wherein the adherend is biodegradable.