Biodegradable film and lid material

Abstract

To provide a biodegradable film which achieves stable easy openability (easy peelability) by cohesive failure at a wide heat seal temperature for various containers using a biodegradable polyester-based resin, has good rigidity, film-forming property, impact resistance and blocking resistance, and is suitably usable for packaging.SOLUTION: A biodegradable film includes a heat seal layer (A) containing a biodegradable polyester-based resin, a flowable modifier, and an inorganic filler, wherein 10 mass% or more of the inorganic filler is contained in the heat seal layer (A), the flowable modifier is polyester having a carboxyl group at least one terminal, and a ratio of the inorganic filler to the flowable modifier is within a range of 1 to 20.SELECTED DRAWING: None

Description

[Technical Field]

[0001] 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 achieve easily peelable and easily openable properties. [Background technology]

[0002] Traditionally, various plastic packaging materials such as packaging bags and containers have widely used materials such as polyethylene, polypropylene, and polyethylene terephthalate. In recent years, these plastic packaging materials have been found to have a significant environmental impact due to their use of fossil resources as raw materials and their inability to decompose for long periods after being discarded in the environment. Therefore, the use of materials with a lower environmental impact, such as bio-resins made from plant-derived raw materials and biodegradable resins that decompose through hydrolysis or biodegradation in soil or water, is being considered.

[0003] Furthermore, packaging materials and lids for packaging bodies and containers are required to be easy to open without applying force. Methods for providing easy opening can be broadly classified into interlayer delamination type, where delamination occurs between the seal layer and the substrate layer directly laminated to it; interfacial delamination type, where delamination occurs between the seal layer and the adherend; and cohesive failure type, where the seal layer is destroyed and delaminates. Interfacial delamination type lids generally tend to have greater fluctuations in seal strength due to the influence of sealing temperature and sealing pressure, and are also susceptible to the influence of the surface condition of the adherend. In contrast, cohesive failure type seal layers have relatively superior stability of seal strength and also have excellent sealing properties against contaminants. In addition, cohesive failure type seals have the advantage of preventing tampering because the delaminated area turns white and the delamination mark remains clearly visible, serving as evidence of opening.

[0004] As an environmentally conscious, easily openable packaging material, the applicants have previously developed a laminated film that possesses suitable heat-sealing properties and easy-opening properties for various materials, including environmentally friendly materials, and is suitable for packaging applications (see Patent Document 1). However, the laminated film described in Patent Document 1 is a film that has easy-opening properties due to interfacial peeling, and the seal strength may fluctuate depending on the sealing temperature and sealing pressure. In addition, the seal strength and airtightness of the laminated film may decrease due to the influence of impurities. Furthermore, the laminated film does not leave any traces at the peeled area and does not have an anti-tampering function.

[0005] Furthermore, a laminated film of the cohesive failure type has been disclosed, which contains inorganic fine particles and a dispersant in a thermoplastic resin (see Patent Document 2). However, because biodegradable resins, especially biodegradable polyester resins, are generally highly polar and have poor fluidity, and tend not to mix well with inorganic fillers, the invention described in Patent Document 2 could not be applied to biodegradable polyester resins. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] WO2021 / 002206 publication [Patent Document 2] Japanese Patent Publication No. 2015-63125 [Overview of the project] [Problems that the invention aims to solve]

[0007] The problem that this invention aims to solve is to provide a biodegradable film that can be used for packaging purposes, which provides stable easy opening (easy peeling) through cohesive failure over a wide range of heat sealing temperatures for various containers made of biodegradable polyester resin, and also has good rigidity, film-forming properties, impact resistance, blocking resistance, etc. [Means for solving the problem]

[0008] The present invention solves the above problems with a biodegradable film comprising a biodegradable polyester resin, a flow modifier, and a heat seal layer (A) containing an inorganic filler, wherein the heat seal layer (A) contains 10% by mass or more of the inorganic filler, the flow modifier is a polyester having a carboxyl group at at least one end, and the ratio of the inorganic filler to the flow modifier is in the range of inorganic filler / flow modifier = 1 to 20. [Effects of the Invention]

[0009] The biodegradable film of the present invention possesses excellent rigidity, film-forming properties, impact resistance, and blocking resistance, making it suitable for packaging applications. Furthermore, the biodegradable film of the present invention exhibits stable heat-sealability and easy-open properties over a wide temperature range, making it suitable for various packaging materials. Moreover, because it achieves easy-open properties through cohesive breakdown over a wide range of heat-sealing temperatures, production line control is simplified.

[0010] Furthermore, because the biodegradable film of the present invention is of the cohesive-breaking type, it is less affected by the surface condition of the adherend compared to the interfacial peel-off type, and has excellent sealing properties for contaminants. In addition, the cohesive-breaking type is particularly suitable for food and medical packaging applications because the peeled area turns white, serving as an indicator of opening and preventing tampering.

[0011] Furthermore, since the biodegradable film of the present invention contains a biodegradable resin in the heat-seal layer and also contains a biodegradable resin in the resin layer laminated with the heat-seal layer, the biodegradable film itself has high environmental compatibility. [Modes for carrying out the invention]

[0012] The biodegradable film of the present invention comprises a biodegradable polyester resin, a flow modifier, and a heat-seal layer (A) containing an inorganic filler, wherein the heat-seal layer (A) contains 10% by mass or more of the inorganic filler, the flow modifier is a polyester having a carboxyl group at least at one end, and the ratio of the inorganic filler to the flow modifier is in the range of inorganic filler / flow modifier = 1 to 20.

[0013] [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, it causes cohesive failure upon opening, thereby achieving easy opening.

[0014] [Biodegradable polyester resin] In this invention, "biodegradable" means that it can be broken down to the molecular level by the action of microorganisms present in soil, water, ocean, etc. Examples of biodegradable polyester resins used in the heat-seal layer (A) of the present invention include polylactic acid resins, polybutylene succinate resins, 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 polylactic acid resins and polybutylene succinate resins in combination.

[0015] Examples of the polylactic acid-based resins mentioned above include polylactic acid (poly(D-lactic acid), poly(L-lactic acid)), copolymers of D-lactic acid and L-lactic acid, copolymers of D-lactic acid and other hydroxycarboxylic acids, copolymers of L-lactic acid and other hydroxycarboxylic acids, and polymers obtained by copolymerizing a polyester component obtained by esterifying dicarboxylic acids and diols with a lactic acid component. Among these, polylactic acid is preferred from the viewpoint of film formation stability and availability, and polylactic acid in which the main structural unit is L-lactic acid is more preferred. These polymers may be used alone or in combination.

[0016] Examples of the hydroxycarboxylic acid, diol, and dicarboxylic acid include hydroxycarboxylic acids such as glycolic acid, hydroxybutyric acid, and hydroxycaproic acids such as hydroxycaproic acid, cyclic lactones such as caprolactone, butyrolactone, lactide, and glycolide; aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; and aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, and sebacic acid.

[0017] Since the polylactic acid-based resin easily realizes good fluidity during extrusion molding, the melt flow rate (190 ° C, 21.18 N) is preferably 0.5 to 30 g / 10 min, more preferably 2 to 25 g / 10 min. When it is within the range of such melt flow rate, extrusion molding is easy, and when co-extrusion multilayered, the fluidity with an adjacent layer is also good, and it becomes easy to obtain a biodegradable film having better appearance.

[0018] Further, the density of the polylactic acid-based resin is preferably 1.20 to 1.26 g / cm 3 and more preferably 1.23 to 1.25 g / cm 3 is more preferable.

[0019] Examples of the polybutylene succinate-based 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 obtained by adding adipic acid in addition to 1,4-butanediol and succinic acid. Such poly(butylene succinate) and poly(butylene succinate / adipate) copolymer can be polymerized to a high molecular weight with lactic acid or a polyfunctional isocyanate compound in order to increase the molecular weight, and can be adjusted to an appropriate molecular weight.

[0020] The melt flow rate (190 °C, 21.18 N) of the polybutylene succinate resin is preferably about 0.5 to 25 g / 10 min, more preferably 1 to 20 g / 10 min, from the viewpoint of film extrusion moldability.

[0021] Also, the density of the polybutylene succinate resin is preferably 1.20 to 1.29 g / cm 3 and more preferably 1.21 to 1.27 g / cm 3

[0022] (Other biodegradable polyester resins) Examples of the other biodegradable polyester resins include aliphatic polyester compounds such as polyglycolic acid, polycaprolactone, and ring-opening polymers such as β-propiolactone and γ-valerolactone; copolyesters of adipic acid, 1,4-butanediol, and terephthalic acid (polybutylene adipate terephthalate), polyesters composed of succinic acid and ethylene glycol (polyethylene succinate), polyesters composed of adipic acid and 1,4-butanediol, polyesters composed of succinic acid and 1,6-hexanediol, etc., i.e., polyesters composed of aliphatic dibasic acids and aliphatic diols; and copolymers thereof.

[0023] Examples of the copolymers of aliphatic polyesters and aromatic polyesters include the above-mentioned aliphatic polyester compounds, or resins obtained by reacting 1 to 50% by mass, preferably 5 to 30% by mass, of aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and p-hydroxybenzoic acid, p-hydroxyethylbenzoic acid, p-hydroxyphenylacetic acid, and aromatic oxycarboxylic acids during the synthesis of these compounds.

[0024] ​Copolymers of polylactic acid and aliphatic polyesters include copolymers of polylactic acid with polyhydric alcohols such as ethylene glycol, 1,2-butylene glycol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, triethylene glycol, dipropylene glycol, dibutanediol, and polytetramethylene glycol, and aliphatic polyesters obtained from polyhydric carboxylic acids such as succinic acid, methylglutaric acid, adipic acid, azelaic acid, sebacic acid, brassic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, maleic anhydride, and fumaric acid. Polymerization catalysts used in the production of lactic acid-based polyesters include, for example, metals and their compounds, particularly metal-organic compounds, carbonates, halides, and especially tin octanoate, zinc chloride, and alkoxytitanium, which are known as transesterification catalysts.

[0025] Commercially available biodegradable polyester resins may be used in this invention. Examples of commercially available products include the "Plaxel" series (polycaprolactone, manufactured by Daicel Corporation) and "BIOMAX" (modified polyester, manufactured by DuPont).

[0026] The biodegradable polyester resin content in the heat seal layer (A) is preferably 80% by mass or more, and more preferably 90% by mass or more, of the total resin components contained in the heat seal layer (A). Furthermore, when multiple biodegradable polyester resins are used in combination, their total content is preferably 80% by mass or more, and more preferably 90% by mass or more, of the total resin components contained in the heat seal layer (A), and the resin components may consist substantially of only these resins. By achieving such a content, biodegradability can be achieved, leading to a reduction in environmental impact.

[0027] (Other biodegradable resins) The heat-seal layer (A) may contain other biodegradable resins as long as they do not impair the effects of the present invention. Examples of other biodegradable resins include polyhydroxyalkanoates such as poly(3-hydroxybutyric acid), copolymers of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, copolymers of 3-hydroxybutyric acid and 4-hydroxybutyric acid; polyvinyl alcohol; pullulan; natural biodegradable resins such as chitosan, starch-based green plastic, esterified starch, cellulose, and cellulose acetate; and the like.

[0028] The other biodegradable resins mentioned above may be used individually or in combination. In addition, commercially available biodegradable resins may be used for the other biodegradable resins mentioned above. Examples of commercially available products include "Mataby" (starch-based, manufactured by Novamont), "Exceval" (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), and "Pullulan" (manufactured by Hayashibara Co., Ltd.).

[0029] When using the above-mentioned other biodegradable resins, it is preferable that the amount of the resin component in the heat seal layer (A) be less than 20% by mass, and more preferably less than 10% by mass. By using such a content, it becomes easier to obtain suitable heat sealability, ease of opening, impact resistance, etc. for various materials.

[0030] (Other resins) Furthermore, the heat-seal layer (A) may contain other resins besides the biodegradable resin described above, as long as they do not impair the effects of the present invention. Examples of such other resins include polyolefin resins such as polyethylene resins and polypropylene resins, and polyester resins. From the viewpoint of reducing environmental impact, it is preferable that such other resins are plant-derived. 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), as well as ethylene-vinyl acetate copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-methacrylic acid copolymers. Examples of polypropylene-based resins include propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, and metallocene catalyst-based polypropylene.

[0031] In addition, resins other than the polyolefin resins mentioned above include, for example, ethylene copolymers such as ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); and furthermore, ionomers of ethylene-acrylic acid copolymer and ionomers of ethylene-methacrylic acid copolymer can be used.

[0032] Furthermore, polyester resins include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid as the dicarboxylic acid component, which is a constituent monomer of polyester. Examples include polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). There are no particular restrictions on the diol component, which is the other constituent monomer of these aromatic polyester resins. Aliphatic diols such as ethylene glycol and 1,4-butanediol are commonly used, but aromatic aliphatic polyester resins (PETG) using aliphatic diols such as cyclohexanedimethanol to reduce crystallinity without lowering the Tg are also frequently used.

[0033] When using any of the above-mentioned other resins, it is preferable that the amount of resin components in the heat seal layer (A) be 10% by mass or less, and more preferably 5% by mass or less.

[0034] [Flow modifier] The heat seal layer (A) of the present invention contains a flow modifier which is a polyester having a carboxyl group at at least one end. This flow modifier has the function of increasing the flowability of the mixture of the biodegradable polyester resin and the inorganic filler. With this flow modifier, the heat seal layer (A) can be made into a film even if the biodegradable polyester resin composition contains a large amount of inorganic filler. As a result, the heat seal layer (A) has easy opening due to cohesive failure.

[0035] The biodegradable polyester resin used in this invention is generally highly polar and prone to becoming highly viscous due to molecular chain entanglement. When a polyester having a carboxyl group at at least one end is added to the biodegradable polyester resin as a fluidity modifier, the carboxyl groups contained in the fluidity modifier are adsorbed onto the inorganic filler, and at the same time, the main chain of the fluidity modifier, which is close in polarity to that of the biodegradable polyester, is thought to ensure compatibility with the biodegradable resin. Furthermore, the fluidity modifier is thought to have the effect of reducing viscosity by interlocking with the molecular chains of the biodegradable polyester and thus untangling them. This is expected to increase the fluidity of the biodegradable polyester resin containing the inorganic filler, making it possible to add a large amount of inorganic filler.

[0036] The above-mentioned fluidity modifier is a polyester having a carboxyl group at least at one end, preferably a polyester having repeating units represented by the following general formula (A) and repeating units represented by the following general formula (G), or a polyester having repeating units represented by the following general formula (L), repeating units represented by the following general formula (A), and repeating units represented by the following general formula (G).

[0037] [ka] (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.)

[0038] The polymerization form of the above-mentioned fluid modifier is not particularly limited and may be a random copolymer containing the above-mentioned repeating units, or a block copolymer containing the above-mentioned repeating units.

[0039] The above-mentioned 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).

[0040] [ka] (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 repetitions and is an integer in the range of 0 to 20.) However, A1 and G1 may be the same or different for each repeating unit enclosed in parentheses.

[0041] A "dibasic acid residue" is an organic group obtained by removing the basic acid functional group from a dibasic acid. For example, if the dibasic acid residue is a dicarboxylic acid residue, the dicarboxylic acid residue refers to the remaining organic group of the dicarboxylic acid after removing the carboxyl group. The number of carbon atoms in a dicarboxylic acid residue does not include the carbon atoms in the carboxyl group. Furthermore, a "diol residue" refers to the remaining organic group after the hydroxyl group has been removed from a diol. Furthermore, "hydroxycarboxylic acid residue" refers to the remaining organic group after removing the hydroxyl group and carboxyl group from a hydroxycarboxylic acid. The number of carbon atoms in a hydroxycarboxylic acid residue does not include the carbon atoms in the carboxyl group.

[0042] The aliphatic dibasic acid residues A, A1, A2, and A3, having 2 to 12 carbon atoms, may include an alicyclic structure and / or an ether bond (-O-). The aliphatic dibasic acid residues A, A1, A2, and A3, having 2 to 12 carbon atoms, are preferably aliphatic dicarboxylic acid residues having 2 to 12 carbon atoms. Examples of such aliphatic dicarboxylic acid residues include succinic acid residues, adipic acid residues, maleic acid residues, pimelic acid residues, suberic acid residues, azelaic acid residues, sebaciic acid residues, cyclohexanedicarboxylic acid residues, dodecanedicarboxylic acid residues, and hexahydrophthalic acid residues.

[0043] The aliphatic dibasic acid residues A, A1, A2, and A3, having 2 to 12 carbon atoms, are preferably aliphatic dicarboxylic acid residues having 2 to 10 carbon atoms, more preferably succinic acid residues, sebacic acid residues, maleic acid residues, and adipic acid residues, and even more preferably sebacic acid residues, maleic acid residues, and adipic acid residues.

[0044] The aromatic dibasic acid residues A, A1, A2, and A3, having 6 to 15 carbon atoms, are preferably aromatic dicarboxylic acid residues having 6 to 15 carbon atoms, and examples of these include phthalic acid residues.

[0045] 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, and even more preferably aliphatic dicarboxylic acid residues having 2 to 10 carbon atoms.

[0046] Examples of aliphatic diol residues with 2 to 9 carbon atoms in G, G1, and G2 include ethylene glycol residues, 1,2-propylene glycol residues, 1,3-propylene glycol residues, 1,2-butanediol residues, 1,3-butanediol residues, 2-methyl-1,3-propanediol residues, 1,4-butanediol residues, 1,5-pentanediol residues, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) residues, and 2,2-diethyl Examples include -1,3-propanediol (3,3-dimethylolpentane) residues, 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane) residues, 3-methyl-1,5-pentanediol residues, 1,6-hexanediol residues, 2,2,4-trimethyl-1,3-pentanediol residues, 2-ethyl-1,3-hexanediol residues, 2-methyl-1,8-octanediol residues, and 1,9-nonanediol residues.

[0047] The aliphatic diol residues of G, G1, and G2, having 2 to 9 carbon atoms, may include an alicyclic structure and / or an ether bond (-O-). Examples of aliphatic diol residues having 2 to 9 carbon atoms and containing the above-mentioned alicyclic structure include 1,3-cyclopentanediol residues, 1,2-cyclohexanediol residues, 1,3-cyclohexanediol residues, 1,4-cyclohexanediol residues, 1,2-cyclohexanedimethanol residues, and 1,4-cyclohexanedimethanol residues. Examples of aliphatic diol residues with 2 to 9 carbon atoms containing the ether bond mentioned above include diethylene glycol residues, triethylene glycol residues, tetraethylene glycol residues, dipropylene glycol residues, and tripropylene glycol residues.

[0048] The aliphatic diol residues of G, G1, and G2 having 2 to 9 carbon atoms are preferably aliphatic diol residues having 3 to 8 carbon atoms, and more preferably ethylene glycol residues, diethylene glycol residues, 1,2-propylene glycol residues, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-butanediol, or 1,3-butanediol residues.

[0049] Examples of hydroxycarboxylic acid residues with 2 to 18 carbon atoms in L include hydroxycarboxylic acid residues in which one hydroxyl group is substituted on the fatty chain of aliphatic carboxylic acids with 3 to 19 carbon atoms, such as propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, caprylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid. Specific examples include lactic acid residues, 9-hydroxystearic acid residues, 12-hydroxystearic acid residues, 6-hydroxycaproic acid residues, 3-hydroxybutyric acid residues, 3-hydroxyvaleric acid residues, 3-hydroxyhexanoic acid residues, 3-hydroxypropionic acid residues, 4-hydroxybutyric acid residues, and 5-hydroxyvaleric acid residues.

[0050] The hydroxycarboxylic acid residue of L having 2 to 18 carbon atoms is preferably an aliphatic hydroxycarboxylic acid residue having 4 to 18 carbon atoms, and more preferably a 12-hydroxystearic acid residue.

[0051] The number of repetitions of n is an integer in the range of 0 to 20, preferably an integer in the range of 1 to 20, and more preferably an integer in the range of 5 to 20.

[0052] The number-average molecular weight (Mn) of the above 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 even more 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 the examples.

[0053] The lower limit of the acid value of the above-mentioned fluidity modifier is not particularly limited, but is preferably 20 or higher, and more preferably 25 or higher. Similarly, the upper limit of the acid value is not particularly limited, but is preferably 400 or lower, and more preferably 200 or lower, 150 or lower, 120 or lower, 100 or lower, and 95 or lower, in that order. The above acid value is confirmed by the method described in the examples.

[0054] The hydroxyl value of the above-mentioned fluid modifier is not particularly limited, but for example, it should be 0 or greater, preferably in the range of 10 to 200, more preferably in the range of 20 to 150, and even more preferably in the range of 50 to 120. The above hydroxyl value is confirmed by the method described in the examples.

[0055] The properties of the above-mentioned fluidity modifiers vary depending on the number-average molecular weight and composition, but they are usually liquid, solid, or paste-like at room temperature.

[0056] The content of the above-mentioned fluidity modifier is not particularly limited, but for example, the fluidity modifier is in the range of 5 to 100 parts by mass per 100 parts by mass of inorganic filler, preferably in the range of 5 to 50 parts by mass, and more preferably in the range of 5 to 30 parts by mass.

[0057] The above-mentioned fluidity modifier can be obtained using reaction raw materials comprising an aliphatic dibasic acid and / or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid. Here, "reaction raw materials" refers to the raw materials that constitute the fluidity modifier in question, and does not include solvents or catalysts that do not constitute the polyester. Furthermore, "any hydroxycarboxylic acid" means that a hydroxycarboxylic acid may or may not be used. The method for producing the fluidity modifier is not particularly limited and can be produced by known methods, or by the production method described later.

[0058] The reaction raw materials for the above-mentioned fluidity modifier may include an aliphatic dibasic acid and / or an aromatic dibasic acid, an aliphatic diol, and any hydroxycarboxylic acid, and may also include other raw materials. The reaction raw materials for the fluidity modifier preferably consist of 90% by mass or more of aliphatic dibasic acids and / or aromatic dibasic acids, aliphatic diols, and any hydroxycarboxylic acids, and more preferably consist only of aliphatic dibasic acids and / or aromatic dibasic acids, aliphatic diols, and any hydroxycarboxylic acids.

[0059] The aliphatic dibasic acid used in the production of the above-mentioned fluidity modifier is an aliphatic dibasic acid corresponding to the aliphatic dibasic acid residues A, A1, A2, and A3 having 2 to 12 carbon atoms. The aliphatic dibasic acid used may be used alone or in combination of two or more types. The aromatic dibasic acid used in the production of the said fluidity modifier is an aromatic dibasic acid corresponding to the aromatic dibasic acid residues A, A1, A2, and A3 having 6 to 15 carbon atoms. The aromatic dibasic acid used may be one type alone or two or more types may be used in combination. The aliphatic diol used in the production of the fluidity modifier is an aliphatic diol corresponding to the aliphatic diol residues with 2 to 9 carbon atoms in G, G1, and G2. The aliphatic diol used may be used alone or in combination of two or more types. The hydroxycarboxylic acid used in the production of the said fluidity modifier is a hydroxycarboxylic acid corresponding to a hydroxycarboxylic acid residue of L having 2 to 18 carbon atoms, and the hydroxycarboxylic acid used may be one type alone or two or more types may be used in combination. The reaction raw materials used include derivatives of the above-mentioned esterified products, acid chlorides, and acid anhydrides. For example, hydroxycarboxylic acids include compounds having a lactone structure, such as ε-caprolactone.

[0060] The above-mentioned fluidity modifier can be produced by reacting aliphatic dibasic acids and / or aromatic dibasic acids, aliphatic diols, and any hydroxycarboxylic acids that constitute each residue of the fluidity modifier under conditions in which the equivalent amount of carboxyl groups contained in the reaction raw materials is greater than the equivalent amount of hydroxyl groups. The fluidity modifier can also be produced by reacting aliphatic dibasic acids and / or aromatic dibasic acids, aliphatic diols, and any hydroxycarboxylic acids that constitute each residue of the fluidity modifier under conditions in which the equivalent amount of hydroxyl groups in the reaction raw materials is greater than the equivalent amount of carboxyl groups to obtain a polyester having hydroxyl groups at the ends of the main chain, and then further reacting the obtained polyester with aliphatic dibasic acids and / or aromatic dibasic acids.

[0061] The above-mentioned fluidity modifier preferably comprises 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, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 2,2-dimethyl-1,3-propanediol. This polyester is reacted with one or more aliphatic diols selected from 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-octanediol, and 1,9-nonanediol as a reaction material.

[0062] The above-mentioned fluidity modifier is a polyester reacted with one or more aliphatic dibasic acids selected from the group consisting more preferably sebacic acid, maleic acid, and adipic acid, and one or more aliphatic diols selected from ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-butanediol, and 1,3-butanediol. These reaction materials can be derived from biomass. This can improve the biomass content of the resulting polyester. Using polyester with a high biomass content in biodegradable resins is preferable from a sustainability perspective.

[0063] In the production of the above-mentioned fluidity modifier, the reaction of the reaction raw materials may be carried out in the presence of an esterification catalyst as needed, for example, at a temperature range of 180 to 250°C for 10 to 25 hours. Furthermore, the temperature, time, and other conditions for the esterification reaction are not particularly limited and may be set as appropriate.

[0064] Examples of the esterification catalysts mentioned above include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; zinc-based catalysts such as zinc acetate; tin-based catalysts such as dibutyltin oxide; and organic sulfonic acid-based catalysts such as p-toluenesulfonic acid.

[0065] The amount of the esterification catalyst used can be set as appropriate, but it is usually used in the range of 0.001 to 0.1 parts by mass per 100 parts by mass of the total amount of reaction raw materials.

[0066] [Inorganic filler] The heat seal layer (A) of the present invention contains an inorganic filler. The inorganic filler is not particularly limited and includes, for example, calcium carbonate, talc, silica, alumina, clay, antimony oxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, calcium silicate, magnesium oxide, potassium titanate, barium titanate, titanium oxide, calcium oxide, magnesium oxide, manganese dioxide, boron nitride, aluminum nitride, and the like. The above inorganic fillers may be used individually or in combination of two or more types.

[0067] 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, and more preferably one or more selected from the group consisting of calcium carbonate, alumina, aluminum hydroxide, and talc.

[0068] The particle size, fiber length, fiber diameter, and other characteristics of the inorganic filler are not particularly limited and may be adjusted as appropriate depending on the intended application. Furthermore, the surface treatment of the inorganic filler is not particularly limited and may be modified with, for example, saturated fatty acids, depending on the intended application.

[0069] The amount of the inorganic filler is, for example, in the range of 1 to 200 parts by mass per 100 parts by mass of the biodegradable polyester resin in the heat seal layer (A), and may be in the range of 1 to 100 parts by mass, 5 to 70 parts by mass, 10 to 60 parts by mass, or 15 to 55 parts by mass. Furthermore, 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 even more preferably 20 to 50% by mass.

[0070] Furthermore, the ratio of the inorganic filler to the fluidity modifier is in the range of inorganic filler / fluidity modifier = 1 to 20. When this ratio is within this range, the increase in viscosity caused by adding a large amount of inorganic filler can be suppressed to a range where film formation is possible by the fluidity modifier. In addition, this range is preferably 2 to 20, and more preferably 3 to 20, as this improves film formation.

[0071] (Other additives) Various additives may be incorporated into the heat-seal layer (A) to the extent that 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 biodegradation-promoting additives. Furthermore, especially when using resins other than the biodegradable resins mentioned above, it is preferable to use biodegradation-promoting additives in order for the film to exhibit biodegradability. Examples of biodegradation-promoting additives include additives containing enzymes, additives containing microorganisms, and additives containing microbial attractants.

[0072] (Resin layer (B)) The biodegradable film of the present invention may be a multilayer film containing a resin layer (B) that is directly laminated with the heat-seal layer (A). The resin layer (B) is preferably made of the biodegradable polyester resin listed in the heat seal layer (A), and more preferably contains the polylactic acid resin and the polybutylene succinate resin as the main resin components. It may also contain other biodegradable polyester resins or other biodegradable resins. By using the resin layer (B), it is possible to suitably laminate it with the heat seal layer (A) while using environmentally friendly materials, and to achieve good peelability of the resulting multilayer film. In the resin layer (B), the biodegradable polyester resin may be used alone or in combination with other resins.

[0073] As the polylactic acid resin, the same type as the polylactic acid resin used in the heat seal layer (A) can be used, and the preferred types, melt flow rate, and density ranges are also the same.

[0074] As the polybutylene succinate resin, the same type as the polybutylene succinate resin used in the heat seal layer (A) can be used, and the preferred types, melt flow rate, and density ranges are also the same.

[0075] As the other biodegradable polyester resins mentioned above, those similar to the other biodegradable polyester resins used in the heat seal layer (A) can be used. Other biodegradable resins can be the same as those used in the heat seal layer (A).

[0076] The content of the biodegradable polyester resin in the resin layer (B) is preferably 80% by mass or more of the total amount of the resin components contained in the resin layer (B), more preferably 90% by mass or more, and preferably substantially consisting only of these resins.

[0077] The resin layer (B) may contain other resins other than those mentioned above, and such other resins may be those exemplified as other resins in the heat seal layer (A). The content of such other resins in the resin layer (B) is preferably less than 10% by mass, and more preferably less than 5% by mass.

[0078] Various additives may be incorporated into the resin layer (B) to the extent that 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 biodegradation-promoting additives. Furthermore, especially when using resins other than the biodegradable resins mentioned above, it is preferable to use biodegradation-promoting additives in order for the film to exhibit biodegradability. Examples of biodegradation-promoting additives include additives containing enzymes, additives containing microorganisms, and additives containing microbial attractants.

[0079] [Biodegradable film] The biodegradable film of the present invention is a biodegradable film having the heat-seal layer (A), and it is preferable that the heat-seal layer (A) and the resin layer (B) are directly laminated to form a multilayer film. The biodegradable film of the present invention, with this configuration, can achieve suitable heat-sealability and easy-open properties for packaging materials of various materials, including environmentally friendly materials. Furthermore, since each layer can be constructed primarily from biodegradable resin, the biodegradable film itself has high environmental compatibility. Furthermore, because easy opening is achieved by cohesive failure of the heat-seal layer (A), stable opening strength can be maintained even if there are fluctuations in the manufacturing process of the biodegradable film of the present invention or fluctuations in the heat-seal temperature. In addition, a lid material with excellent impurity sealing properties can be obtained. Moreover, because easy opening is achieved by cohesive failure, the peeled area turns white, which serves as proof of opening and prevents unauthorized opening.

[0080] In the biodegradable film of the present invention, the heat-seal layer (A) constitutes one of the surface layers of the film. The surface layer opposite the heat seal layer (A) may be a resin layer (B), but it is also preferable to laminate another resin layer (C) that constitutes the surface layer, as this can make it easier to obtain stability during manufacturing and suitable film formation properties while appropriately adjusting the thickness of the heat seal layer.

[0081] The resin layer (C) can preferably be the same as the resin layer (B), and may have the exact same resin composition as resin layer (B), or a different resin composition. Using the same resin formulation is preferable because it simplifies manufacturing. Furthermore, by using different resin formulations, it becomes easier to adjust the physical properties of the multilayer film.

[0082] Furthermore, another resin layer (D) may be provided between resin layer (C) and resin layer (B). In particular, in the present invention, since the proportion of layers other than the heat seal layer (A) is high, a four-layer structure is preferable because it facilitates thickness adjustment with respect to the heat seal layer (A) when using the co-extrusion method, and makes it easier 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 formulation preferred to that of the resin layer (B) and resin layer (C). The resin composition of resin layer (D) may be the exact same mixture as that of resin layer (B) and resin layer (C), or it may be a mixture with different resin formulations, MFRs, and densities.

[0083] Examples of specific preferred layer configurations include heat seal layer (A) / resin layer (B), heat seal layer (A) / resin layer (B) / resin layer (C), heat seal layer (A) / resin layer (B) / resin layer (C), heat seal layer (A) / resin layer (B) / resin layer (D) / resin layer (C), and so on.

[0084] The thickness (total thickness) of the biodegradable film of the present invention is preferably 20 to 70 μm, and more preferably in the range of 20 to 50 μm, from the viewpoint of reducing the weight of the packaging material and from the viewpoint of easy opening.

[0085] The thickness of the heat seal layer (A) is preferably in the range of 8 to 90% of the total film thickness, and more preferably in the range of 10 to 70%. When a biodegradable film has a three-layer structure consisting of a heat-seal layer (A), a resin layer (B), and a resin layer (C), it is preferable that the thickness of resin layer (B) be 10-82% of the total film thickness and the thickness of resin layer (C) be 10-40%, and more preferably that the thickness of resin layer (B) be 20-60% and the thickness of resin layer (C) be 10-30%. When a biodegradable film has a four-layer structure consisting of a heat-seal layer (A), a resin layer (B), a resin layer (D), and a resin layer (C), it is preferable that the thickness of resin layer (B) be 10-30% of the total film thickness, the thickness of resin layer (C) be 20-60%, and the thickness of resin layer (D) be 10-35%, and more preferably that the thickness of resin layer (B) be 10-25%, the thickness of resin layer (C) be 25-55%, and the thickness of resin layer (D) be 10-30%.

[0086] Specifically, the thickness of the heat seal layer (A) is preferably 2 to 45 μm, more preferably 3 to 35 μm.

[0087] The biodegradable film of the present invention can achieve excellent environmental compatibility because each layer is composed of a biodegradable resin. Because of its particularly 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 a film in which the resin component consists substantially only of these resins is also particularly preferable because it ensures the biodegradability of the film itself. Furthermore, using polylactic acid-based resin and / or polybutylene succinate-based resin as the main resin components of resin layers (B), (C), and (D) is preferable as it makes it easier to achieve both biodegradability and film properties. Furthermore, using plant-derived biomass resin as the resin component for each layer allows for environmental friendliness to be added relatively inexpensively.

[0088] (Method for manufacturing biodegradable film) The method for producing the biodegradable film of the present invention is not particularly limited, but examples include a co-extrusion method in which each resin or resin mixture used in each layer is heated and melted in separate extruders, and then, in a molten state, only a heat-seal layer (A), a heat-seal layer (A) / resin layer (B), a heat-seal layer (A) / resin layer (B) / resin layer (C), or a heat-seal layer (A) / resin layer (B) / resin layer (D) / resin layer (C) is laminated, and then formed into a film by inflation or a T-die chill roll method. The co-extrusion method is preferable because it allows for relatively free adjustment of the thickness ratio of each layer, resulting in a multilayer film that is hygienic and cost-effective. Furthermore, the biodegradable film of the present invention contains a flow modifier and exhibits excellent processability. When laminating resins with a large difference between their melting point and Tg, the film's appearance may deteriorate or it may become difficult to form a uniform layer structure during co-extrusion. To suppress such deterioration, the T-die chill-roll method, which allows for melt extrusion at relatively high temperatures, is preferred. Alternatively, a single-layer film consisting only of a heat-seal layer (A) may be extruded, or a resin film corresponding to a resin layer (B) may be laminated onto one surface of the single-layer film by dry lamination or the like to form a multilayer film.

[0089] Furthermore, as a resin mixture to be used for the heat seal layer (A), a masterbatch may be prepared by increasing the blending ratio of the inorganic filler and the fluidity modifier relative to the resin, and this masterbatch may be diluted with a biodegradable polyester resin to be used as the resin mixture for the heat seal layer of the present invention. The preferred blending ratio of each component in the masterbatch is 20-80% by mass for the inorganic filler, 1-20% by mass for the fluidity modifier, and 20-79% by mass for the resin.

[0090] Furthermore, as the resin mixture used for the heat seal layer (A), a masterbatch may be prepared in which the ratio of the fluidity modifier to the resin is increased, and an inorganic filler may be kneaded into this masterbatch to obtain the resin mixture used for the heat seal layer of the present invention. Preferably, the ratio of each component in the masterbatch is 1 to 20% by mass of the fluidity modifier and 80 to 99% by mass of the resin.

[0091] When printing or laminating is performed on the surface other than the heat-seal layer (A), it is preferable to apply a surface treatment to the surface other than the heat-seal layer (A) in order to improve adhesion with printing inks and adhesives. 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, or surface roughening treatments such as sandblasting, but corona treatment is preferred.

[0092] [Laminating 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 substrate onto the surface other than the heat-seal layer (A) to form a laminate film. While there are no particular limitations on the laminating substrate, it is generally preferable to use a stretched substrate film, as this ensures sufficient strength to prevent breakage, provides heat resistance during heat sealing, and improves the design of the printed surface. As the stretched base film, biaxially oriented polyester film, biaxially oriented nylon film, biaxially oriented polypropylene film, etc., can be used. Furthermore, laminating with a biodegradable base film such as stretched polylactic acid film, paper, or cellophane is preferable because it ensures the biodegradability of the entire laminate film. The base film may be treated with tear-resistant or antistatic treatments as needed.

[0093] The method for manufacturing the laminate film is not particularly limited, but one example is to laminate a laminate substrate onto a heat-seal layer (A), a resin layer (B), or a resin layer (C) that forms the surface of the biodegradable film. Methods for laminating a laminate substrate to the biodegradable film of the present invention include, for example, dry lamination, heat lamination, and multilayer extrusion coating, but among these, dry lamination is more preferred. Furthermore, examples of adhesives used when laminating the biodegradable film with the laminate substrate using the dry lamination method include polyether-polyurethane adhesives and polyester-polyurethane adhesives. Furthermore, it is preferable to apply corona discharge treatment to the surface of the biodegradable film before laminating the biodegradable film with the substrate, as this improves adhesion to the substrate.

[0094] [Packaging] 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, confectionery containers, rice containers, instant noodle containers, etc., and is especially suitable as a lid material to be attached to a packaging container having an opening.

[0095] The packaging container having an opening to be adhered to is preferably biodegradable, and examples include various packaging containers made from biodegradable polyester resins such as polylactic acid polymers, polybutylene succinate polymers, paper / polylactic acid polymers, paper / polybutylene succinate polymers, and polyethylene terephthalate. In particular, it is preferable to use a packaging container with a polybutylene succinate polymer on the adherend surface. The biodegradable film of the present invention can achieve suitable heat-sealability and easy-open properties for packaging containers made of these various materials. [Examples]

[0096] Next, the present invention will be described in more detail with reference to examples and comparative examples.

[0097] <Synthesis of fluidity modifiers> (Synthesis Example 1) In a 2-liter four-necked flask equipped with a thermometer, stirrer, and reflux condenser, 876.8 g of adipic acid, 612.7 g of 1,3-butanediol, 78.7 g of neopentyl glycol, and 0.047 g of tetraisopropyl titanate as an esterification catalyst were charged. The mixture was then heated in stages under a nitrogen atmosphere with stirring until it reached 220°C, and the condensation reaction was carried out for a total of 14 hours. 13.1 g of maleic anhydride was then added to 250 g of the resulting reaction product, and the reaction was completed at 120°C to obtain polyester-based fluidity modifier A (acid value: 29, hydroxyl value: 73, number average molecular weight: 1,290).

[0098] (Synthesis Example 2) In a 0.5-liter four-necked flask equipped with a thermometer, stirrer, and reflux condenser, 200 g of GI-1000 (manufactured by Nippon Soda Co., Ltd., hydroxylated polybutadiene at both ends) and 10.5 g of maleic anhydride were charged and reacted at 120°C for 3 hours to obtain polyolefin-based fluidity modifier B (acid value: 30, number average molecular weight: 2,600).

[0099] (Synthesis Example 3) In a 0.5-liter four-necked flask equipped with a thermometer, stirrer, and reflux condenser, 200 g of GI-3000 (manufactured by Nippon Soda Co., Ltd., hydroxylated polybutadiene at both ends) and 10.5 g of maleic anhydride were charged and reacted at 120°C for 3 hours to obtain polyolefin-based fluidity modifier C (acid value: 30, number average molecular weight: 5,920).

[0100] (Measurement of number-average molecular weight) In the embodiments of this invention, the number-average molecular weight of the fluidity modifier is a value converted to polystyrene based on GPC measurement, and the measurement conditions are as follows. [GPC measurement conditions] Measurement device: Tosoh Corporation high-speed GPC system "HLC-8320GPC" Columns: Tosoh Corporation's "TSK GURDCOLUMN SuperHZ-L" + Tosoh Corporation's "TSK gel SuperHZM-M" + Tosoh Corporation's "TSK gel SuperHZM-M" + Tosoh Corporation's "TSK gel SuperHZ-2000" + Tosoh Corporation's "TSK gel SuperHZ-2000" Detector: RI (Differential Refractometer) Data processing: EcoSEC Data Analysis version 1.07 manufactured by Tosoh Corporation. Column temperature: 40℃ Developing solvent: tetrahydrofuran Flow rate: 0.35mL / min Measurement sample: 7.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran, and the resulting solution was filtered through a microfilter to be used as the measurement sample. Sample injection volume: 20 μl Standard sample: In accordance with the measurement manual for "HLC-8320GPC" mentioned above, the following monodisperse polystyrenes with known molecular weights were used.

[0101] (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 Tosoh Corporation's "F-10" F-20 manufactured by Tosoh Corporation Tosoh Corporation's "F-40" Tosoh Corporation's "F-80" Tosoh Corporation's "F-128" Tosoh Corporation's "F-288"

[0102] In the embodiments of this invention, the acid value and hydroxyl value are values ​​evaluated by the following method. Acid value: Measured according to the method in accordance with JIS K0070-1992. Hydroxyl value: Measured according to the method in accordance with JIS K0070-1992.

[0103] <Evaluation of compatibility> 100 parts by mass of polybutylene succinate (Bio-PBS FZ91PM, manufactured by PTTMCC Biochem) and 5 parts by mass of a fluidity modifier were mixed in a mixer at 120°C for 10 minutes, and then pressed into a 1 mm thick sheet using a hot press. The resulting sheet was left at room temperature for 10 days, and the surface condition of the sheet was checked by touch. Sheets with no stickiness on the surface and no bleeding of the fluidity modifier were judged as having excellent compatibility (◎), while sheets with stickiness on the surface and bleeding of the fluidity modifier were judged as having poor compatibility (×).

[0104] [Table 1]

[0105] <Preparation of samples for disintegration testing> (Sample 1) As resin components forming the heat-seal layer (A) and the resin layer (B), resin mixtures for each layer were prepared according to the blending ratios shown in Table 1 below. The resin mixtures for each layer were melted and supplied to two extruders, respectively, and co-extruded into a T-die chill-roll co-extrusion multilayer film manufacturing apparatus (feed block and T-die temperature: 200°C) equipped with a feed block, so that the thickness of each layer of the multilayer film formed by the heat-seal layer (A) and resin layer (B) was 3 μm / 27 μm. The mixtures were cooled with a water-cooled metal cooling roll at 40°C to form a biodegradable film with a total thickness of 30 μm. This film was cut into 3 cm x 3 cm pieces and designated as Sample 1.

[0106] (Samples 2, 3) Samples 2 and 3 were prepared in the same manner as Sample 1, except that the mixing ratios and layer thicknesses of each layer were changed as shown in Table 1.

[0107] (Sample 4) Polypan Mat 7283-2 (manufactured by DIC Corporation, a low-density polyethylene-based talc masterbatch) was melted and fed into an extruder to produce a 30 μm film. The resulting sheet was cut into 3 cm x 3 cm sections, which were designated as Sample 4.

[0108] <Assessment of disintegration potential> A glass bottle was filled with soil (30 wt% moisture content) collected from a field in Ichihara City, Chiba Prefecture, and a test specimen was buried in the soil. The glass bottle was then sealed and left in a 60°C constant temperature bath for four weeks before the test specimen was retrieved. A test specimen that had decomposed to the point where it was difficult to retrieve visually was judged to have excellent disintegration properties (◎), while a test specimen whose appearance and weight had not changed was judged to have poor disintegration properties (×).

[0109] [Table 2]

[0110] [Table 3]

[0111] The ingredients listed in Table 1 are as follows: PBS: Polybutylene succinate copolymer (PTTMCC, Biochem "FZ91PB", density: 1.26 g / cm³) 3 Melting point 115℃, MFR: 5g / 10min (190℃, 21.18N) Fluidity modifier A: Fluidity modifier A from synthesis example 1 Talc (hydrated magnesium silicate: 3MgO·4SiO2·H2O): Micron White 5000A (manufactured by Hayashi Chemical Co., Ltd.)

[0112] 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, showed good biodegradability. On the other hand, sample 4, which does not exhibit biodegradability, did not biodegrade.

[0113] <Manufacturing of biodegradable films> (Example 1) As resin components for forming the heat-seal layer (A) and the resin layer (B), resin mixtures for each layer were prepared according to the blending ratios shown in Table 1 below. The resin mixtures for each layer were melted and supplied to two extruders, respectively, and co-extruded into a T-die chill-roll co-extrusion multilayer film manufacturing apparatus (feed block and T-die temperature: 200°C) with a feed block, so that the thickness of each layer of the multilayer film formed by the heat-seal layer (A) and resin layer (B) was 7.5 μm / 22.5 μm. The mixtures were then cooled with a water-cooled metal cooling roll at 40°C to form the biodegradable film of Example 1 with a total thickness of 30 μm.

[0114] (Examples 2-4) Biodegradable films of Examples 2-4 were molded in the same manner as in Example 1, except that the mixing ratio and thickness of each layer were changed as shown in Table 3.

[0115] (Comparative Examples 1-3) The biodegradable films of Comparative Examples 1 to 3 were molded in the same manner as in Example 1, except that the mixing ratio and thickness of each layer were changed as shown in Table 4.

[0116] [Table 4]

[0117] [Table 5]

[0118] The ingredients used are as follows: PBS: Polybutylene succinate copolymer (PTTMCC, Biochem "FZ91PB", density: 1.26 g / cm³) 3 Melting point 115℃, MFR: 5g / 10min (190℃, 21.18N) PLA: Polylactic acid resin (Nature Works "3001D", density: 1.24 g / cm³) 3(ASTM D792), MFR: 22 g / 10 min (210 °C, 1.26 kg) Talc (hydrated magnesium silicate: 3MgO·4SiO2·H2O): Micron White 5000A (manufactured by Hayashi Kasei Co., Ltd.) Flowability modifiers A - C: Flowability modifiers A - C of Synthesis Examples 1 - 3

[0119] The following evaluations were performed on the films obtained in the above Examples and Comparative Examples. The obtained results are shown in Tables 4 and 5.

[0120] (Production of laminated film) A cellophane film (thickness 20 μm) was dry - laminated onto the surface of the biodegradable film substrate layer (B) side or the surface of the single - layer film obtained in the above Examples and Comparative Examples to obtain a laminated film. At this time, as the dry - lamination adhesive, a two - component curing adhesive (polyester - based adhesive "LX500" and curing agent "KR - 90") manufactured by DIC Corporation was used.

[0121] (Evaluation of film - forming property) During the film production in the Examples and Comparative Examples, the occurrence of gels and holes was confirmed. 〇: Film can be formed, and the number of holes generated is 1 hole / m 2 as follows. △: Film can be formed, but the number of holes generated is 2 holes / m 2 or more. ×: Film cannot be formed.

[0122] (Evaluation of rigidity) The 1% secant modulus measured as follows for the films obtained in the above Examples and Comparative Examples was used as the rigidity (hardness), and evaluated according to the following criteria. The measurement of the 1% secant modulus was carried out using a film cut out to a size of 300 mm in length × 25.4 mm in width (gage length 200 mm) with the longitudinal direction being the flow direction (vertical direction) of the film as a test piece, and in accordance with ASTM D - 882 under the condition of a tensile speed of 20 mm / min. ○: 350 MPa or more. ×: Less than 350 MPa.

[0123] (Impact resistance evaluation) Test specimens were prepared by leaving the films obtained in the examples and comparative examples to stand for 4 hours in a constant temperature room adjusted to 0°C. For each test specimen, the impact strength was measured using the film impact method with a BU-302 film impact tester manufactured by Tester Industries, using a 1.5-inch head attached to the tip of a pendulum. ○: Impact strength of 0.10J or more ×: Impact strength less than 0.10J

[0124] (Evaluation of blocking resistance) Ten 10cm square pieces of film obtained from the examples and comparative examples were cut and subjected to a 400g load, and stored at 40°C for one month. The strength of the adhered films was then measured by cutting them into 15mm wide strips and using a tensile testing machine (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50%RH to perform a 90° peel at a speed of 300mm / min, and measuring the blocking strength. ○: Blocking strength is less than 100g / 15mm. ×: Blocking strength of 100g / 15mm or more.

[0125] (Evaluation of heat sealability (ease of peeling) to PBS sheets) The laminate film obtained in the above-mentioned lamination process and a PBS sheet (polybutylene succinate resin, 100 μm thick) were heat-sealed at temperatures ranging from 110 to 150 °C in 10 °C increments (0.2 MPa, 1 second). The sealed samples were cut into 15 mm strips to form test pieces. These test pieces were then subjected to a 180° peel at a speed of 300 mm / min using a tensile testing machine (manufactured by A&D Co., Ltd.) in a constant temperature room at 23 °C and 50% RH to measure the heat seal strength, which was then evaluated according to the following criteria. ◎: Heat seal strength of 5N / 15mm or more and 20N / 15mm or less at all temperatures. ○: Heat seal strength of 5N / 15mm or more and 35N / 15mm or less at all temperatures. △: There are 1-2 temperature levels where the heat seal strength is less than 5N / 15mm or greater than 35N / 15mm. ×: Heat seal strength is less than 5N / 15mm, or there are three or more temperatures at which the film breaks without peeling off the seal surface.

[0126] (Scratches) The laminate film obtained in the above lamination process and a PBS sheet (thickness 100 μm) were heat-sealed at 140°C (0.2 MPa, 1 second). The sealed samples were cut into 15 mm strips to form test pieces. These test pieces were then peeled 180° at a speed of 300 mm / min using a tensile testing machine (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH, and the peeling process was evaluated according to the following criteria. ○: The force required for peeling is constant, smooth peeling is easy, and the peeling marks are clear. ×: The force required for peeling is inconsistent, resulting in a lack of smoothness in the peeling process. Alternatively, no peeling marks are visible.

[0127] (Evaluation of heat sealability (ease of peeling) to PLA sheets) The laminate film obtained in the above-mentioned lamination process and a PLA sheet (300 μm thick) were heat-sealed at 120°C and 150°C (0.2 MPa, 1 second). The sealed samples were cut into 15 mm strips to form test pieces. These test pieces were then peeled 180° at a speed of 300 mm / min using a tensile testing machine (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH to measure the heat seal strength, which was evaluated according to the following criteria. ◎: Heat seal strength of 5N / 15mm or more and 20N / 15mm or less at all temperatures. ○: Heat seal strength of 5N / 15mm or more and 35N / 15mm or less at all temperatures. ×: Heat seal strength is less than 5N / 15mm, or the temperature at which film breakage occurs without peeling at the seal surface is 1 level or higher.

[0128] (Evaluation of heat sealability (ease of peeling) on ​​each surface) The laminate films obtained in the above-mentioned preparation process were stacked with their heat-sealed (A) layers facing each other, and heat-sealed at 120°C and 150°C (0.2 MPa, 1 second). The sealed samples were cut into 15 mm strips to form test pieces. These test pieces were then subjected to a 180° peel at a speed of 300 mm / min using a tensile testing machine (manufactured by A&D Co., Ltd.) in a constant temperature room at 23°C and 50% RH to measure the heat-seal strength, which was then evaluated according to the following criteria. ◎: Heat seal strength of 5N / 15mm or more and 20N / 15mm or less at all temperatures. ○: Heat seal strength of 5N / 15mm or more and 35N / 15mm or less at all temperatures. ×: Heat seal strength is less than 5N / 15mm, or the temperature at which film breakage occurs without peeling at the seal surface is 1 level or higher.

[0129] As is clear from Tables 4 and 5 above, the biodegradable films of the present invention in Examples 1 to 4, while using biodegradable resins, exhibited stable and easy peelability over a wide range of heat-seal temperatures on adherends made of biodegradable polyester resins such as polybutylene succinate resin and polylactic acid, and possessed rigidity, film-forming properties, impact resistance, and blocking resistance suitable for packaging applications. Furthermore, the clear peel marks indicate that the peeling is due to cohesive failure, and the seal strength and airtightness do not deteriorate easily even in the presence of impurities. In addition, the peel marks make it visible that the package has been opened, thus preventing unauthorized opening. On the other hand, the biodegradable film of Comparative Example 1 lacked both a fluidity modifier and an inorganic filler, resulting in poor peelability. The biodegradable film of Comparative Example 2 contained talc as an inorganic filler but lacked a fluidity modifier, making film formation impossible. The biodegradable film of Comparative Example 3 contained both an inorganic filler and a fluidity modifier, but the ratio was inorganic filler / fluidity modifier = 30, and the amount of fluidity modifier was insufficient relative to the amount of inorganic filler, making film formation impossible. The biodegradable films of Comparative Examples 4 and 5 could not be film-formed because the fluidity modifier used was not a polyester having a carboxyl group at at least one end.

Claims

1. It comprises a biodegradable polyester resin, a flow modifier, and a heat seal layer (A) containing 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 of its ends. The acid value of the aforementioned fluidity modifier is 20 or more and 95 or less. The number average molecular weight of the aforementioned fluid modifier is 100 to 5,000. 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.

2. 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.

3. The biodegradable film according to claim 1, wherein the biodegradable polyester resin used in the heat seal layer (A) is a polylactic acid resin or a polybutylene succinate resin.

4. The biodegradable film according to Claim 1, wherein the fluidity modifier is a polyester having repeating units represented by the following general formula (A) and repeating units represented by the following general formula (G), or a polyester having repeating units represented by the following general formula (L), repeating units represented by the following general formula (A), and repeating units represented by the following general formula (G). (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.)

5. The biodegradable film according to claim 1, which, when adhered to an object, has easy opening due to cohesive failure of the heat seal layer (A).

6. A laminate film comprising the biodegradable film described in claims 1 to 5.

7. A packaging body comprising a biodegradable film according to any one of claims 1 to 5 and an adherend, wherein the layer that adheres to the heat-seal layer (A) of the adherend contains a polybutylene succinate resin as the main resin component.

8. The packaging according to claim 7, wherein the adherend is biodegradable.

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