Tearable film, multilayer film, packaging material, container, and resin composition for forming tearable film

Abstract

To provide a tearable film with superior linear cuttability and deposition stability, a multilayer film, a packaging material, a container, and a resin composition for forming a tearable film.SOLUTION: A tearable film is composed of a resin composition that contains a polybutylene terephthalate resin and a polyamide resin. When the total amount of the polybutylene terephthalate resin and the polyamide resin is 100 pts.mass, the content of the polybutylene terephthalate resin is 95-75 pts.mass. The polyamide resin contains diamine constitutional units including 70 mol% or more of xylylene diamine constitutional units, and dicarboxylic acid constitutional units including 70 mol% or more of C4-8 α,ω-linear aliphatic dicarboxylic acid constitutional units. The polybutylene terephthalate resin has a melt volume rate (MVR) of 5-15 cm3 / 10 min as measured by at 250°C, 2.16 kg load.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a tearable film, a multilayer film, a packaging material, a container, and a resin composition for forming an easily tearable film, and more particularly to an easily tearable film containing a polyamide resin and a polybutylene terephthalate resin. [Background technology]

[0002] Polybutylene terephthalate resins have been widely used in packaging materials such as films, sheets, hollow containers, etc., because of their excellent mechanical properties, melt stability, etc. However, their gas barrier properties against oxygen, carbon dioxide, etc. are not necessarily good, and therefore their use in applications requiring high gas barrier properties has been limited. On the other hand, polyamide resin obtained by polymerizing metaxylylenediamine and adipic acid (hereinafter sometimes referred to as "polyamide MXD6") has high gas barrier properties and excellent thermal stability when melted. Therefore, it has the advantage of being easily melt-mixed with aromatic polyester resin.

[0003] Here, Patent Document 1 describes a film containing polybutylene terephthalate resin and MXD6. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-302952 A Summary of the Invention [Problem to be solved by the invention]

[0005] The film described in the above Patent Document 1 has excellent gas barrier properties, but no consideration has been given to using it as an easily tearable film. Furthermore, the present inventors conducted research and found that the film described in the above Patent Document 1, for example, a film containing polybutylene terephthalate resin, MXD6, and pyromellitic anhydride (PMDA), has poor linear cut properties. Further investigations by the present inventors revealed that, unlike the case where a polyamide resin is blended with a polyethylene terephthalate resin, blending a polyamide resin with a polybutylene terephthalate resin may result in poor film formation stability. The present invention aims to solve the above problems, and aims to provide a tearable film having excellent linear cut properties and excellent film formation stability, as well as a multilayer film, a packaging material, and a container using the tearable film, and a resin composition for forming the tearable film. [Means for solving the problem]

[0006] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by adjusting the melt volume rate of a polybutylene terephthalate resin and making the resin substantially free of a specified polycarboxylic acid compound. Specifically, the above problems were solved by the following means. <1> An easily tearable film formed from a resin composition containing a polybutylene terephthalate resin and a polyamide resin, the polybutylene terephthalate resin being 95 to 75 parts by mass when the total amount of the polybutylene terephthalate resin and the polyamide resin is taken as 100 parts by mass, the polyamide resin containing a diamine structural unit containing 70 mol % or more of a xylylene diamine structural unit and a dicarboxylic acid structural unit containing 70 mol % or more of an α,ω-linear aliphatic dicarboxylic acid structural unit having 4 to 8 carbon atoms, the polybutylene terephthalate resin having a melt volume rate (MVR) of 5 to 15 cm as measured at 250°C under a load of 2.16 kg. 3 / 10 min, and the total content of a polycarboxylic acid compound having three or more carboxyl groups bonded to an aromatic ring in one molecule and / or a polycarboxylic acid compound in which two or more of the carboxyl groups bonded to the compound form an anhydride ring is 0 parts by mass or more and less than 0.01 parts by mass relative to 100 parts by mass of the total amount of polybutylene terephthalate resin and polyamide resin. <2> 70 mol % or more of the dicarboxylic acid constituent units are adipic acid constituent units. <1> The easily tearable film according to claim 1. <3> The melt volume rate (MVR) of polybutylene terephthalate resin measured at 250°C under a load of 2.16 kg is 8 to 15 cm 3 / 10min, <1> or <2> The easily tearable film according to claim 1. <4> The relative viscosity of the polyamide resin in a 96% sulfuric acid solution measured at 25°C according to JIS K 6920-2 is 1.9 to 2.3. <1> ~ <3> 13. The easily tearable film according to claim 12 . <5> 70 mol % or more of the dicarboxylic acid constitutional units are derived from adipic acid, and the melt volume rate (MVR) of the polybutylene terephthalate resin measured at 250° C. under a load of 2.16 kg is 8 to 15 cm 3 / 10min, and the relative viscosity of the polyamide resin in a 96% sulfuric acid solution measured at 25°C according to JIS K 6920-2 is 1.9 to 2.3. <1> ~ <4> 13. The easily tearable film according to claim 12 . <6> The easily tearable film is a stretched film. <1> ~ <5> 13. The easily tearable film according to claim 12 . <7> <1> ~ <6> A multilayer film having the easily tearable film according to any one of the above. <8> <1> ~ <6> A packaging material having the easily tearable film described in any one of the above. <9> <1> ~ <6> A container having the easily tearable film described in any one of the above. <10> Contains polybutylene terephthalate resin and polyamide resin, A resin composition for forming an easily tearable film, comprising 95 to 75 parts by mass of a polybutylene terephthalate resin when the total amount of the polybutylene terephthalate resin and the polyamide resin is 100 parts by mass, The polyamide resin contains a polyamide resin having a diamine constituent unit containing 70 mol % or more of a xylylenediamine constituent unit and a dicarboxylic acid constituent unit containing 70 mol % or more of an α,ω-linear aliphatic dicarboxylic acid constituent unit having 4 to 8 carbon atoms, and the melt volume rate (MVR) of the polybutylene terephthalate resin measured at 250° C. under a load of 2.16 kg is 5 to 15 cm 3 / 10 min, and the total content of a polyvalent carboxylic acid compound having three or more carboxyl groups bonded to an aromatic ring in one molecule and / or a polyvalent carboxylic acid compound having two or more of the carboxyl groups bonded to the compound forming an anhydride ring is 0 parts by mass or more and less than 0.01 parts by mass relative to 100 parts by mass of the total amount of the polybutylene terephthalate resin and the polyamide resin. Resin composition. Effect of the Invention

[0007] According to the present invention, it is possible to provide a tearable film having excellent linear cut properties and excellent film formation stability, as well as a multilayer film, a packaging material, and a container using the tearable film. It is also possible to provide a resin composition for forming the tearable film. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is an image diagram illustrating a method for evaluating the straight line cutting property in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment. In this specification, the use of "to" means that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23° C. unless otherwise specified.

[0010] In this specification, unless otherwise specified, the number average molecular weight is a value measured by the following method. The number average molecular weight (Mn) is measured by gel permeation chromatography (GPC) using a standard polymethyl methacrylate (PMMA) equivalent value. Two columns packed with styrene polymers are used as the packing material, and hexafluoroisopropanol (HFIP) with a sodium trifluoroacetate concentration of 2 mmol / L is used as the solvent. The resin concentration is 0.02 mass%, the column temperature is 40°C, the flow rate is 0.3 mL / min, and the measurement is performed using a refractive index detector (RI). In addition, the calibration curve is measured by dissolving six levels of PMMA in HFIP.

[0011] In this specification, the melting point (Tm) and glass transition temperature (Tg) are values ​​measured according to differential scanning calorimetry (DSC) in accordance with ISO11357, unless otherwise specified. A differential scanning calorimeter is used, and the resin is placed in the measurement pan of the differential scanning calorimeter, heated to a temperature above the melting point at a heating rate of 10°C / min under a nitrogen atmosphere, and then rapidly cooled before measurement. The measurement conditions are a heating rate of 10°C / min, held at 280°C for 5 minutes, and then cooled down to 100°C at a cooling rate of -5°C / min to determine the melting point (Tm) and glass transition temperature (Tg). As the differential scanning calorimeter, a "DSC-60" manufactured by SHIMADZU CORPORATION is used.

[0012] The terms "film" and "sheet" as used herein refer to generally flat molded bodies that are thin relative to their length and width. The terms "film" and "sheet" as used herein may be single-layer or multi-layer. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards as of January 1, 2023, unless otherwise stated.

[0013] The easily tearable film of the present embodiment contains a polybutylene terephthalate resin and a polyamide resin, and is formed from a resin composition containing 95 to 75 parts by mass of polybutylene terephthalate resin when the total amount of the polybutylene terephthalate resin and the polyamide resin is 100 parts by mass. The polyamide resin contains a polyamide resin (hereinafter sometimes referred to as a "xylylenediamine-based polyamide resin") having diamine structural units containing 70 mol % or more of xylylenediamine structural units and dicarboxylic acid structural units containing 70 mol % or more of α,ω-linear aliphatic dicarboxylic acid structural units having 4 to 8 carbon atoms, and the melt volume rate (MVR) of the polybutylene terephthalate resin measured at 250° C. under a load of 2.16 kg is 5 to 15 cm. 3 / 10 min, and the total content of a polycarboxylic acid compound having three or more carboxyl groups bonded to an aromatic ring in one molecule and / or a polycarboxylic acid compound in which two or more of the carboxyl groups bonded to the compound form an anhydride ring is 0 parts by mass or more and less than 0.01 parts by mass relative to 100 parts by mass of the total amount of the polybutylene terephthalate resin and the polyamide resin. By adopting such a constitution, it is possible to provide an easily tearable film that has excellent linear cuttability and excellent film formation stability. Unlike the blend film of polyethylene terephthalate resin and polyamide resin, the blend film of polybutylene terephthalate resin and polyamide resin tends to have poor film formation stability. One of the reasons for this is that the resin composition containing polybutylene terephthalate resin and polyamide resin has a faster crystallization rate than the resin composition containing polyethylene terephthalate resin and polyamide resin. Therefore, the present inventor decided to rapidly cool the molten resin immediately after extrusion from the die when forming the stretched raw film, and further decided to use a polybutylene terephthalate resin with a higher viscosity, specifically, a resin with a lower melt volume rate (MVR). In addition, it was found that even in the case of a blend film of polybutylene terephthalate resin and polyamide resin, when a film containing pyromellitic anhydride (PMDA) is used, the linear cut property is poor, as described in the above Patent Document 1. When the reason for this was investigated, it was found that linear cut property is due to the ease of peeling between polybutylene terephthalate resin and xylylenediamine-based polyamide resin, and the ease of tearing of xylylenediamine-based polyamide resin, but pyromellitic anhydride (PMDA) inhibits these factors. That is, in Patent Document 1, it was found that pyromellitic anhydride (PMDA) makes it easier to bond between polybutylene terephthalate resin and xylylenediamine-based polyamide resin, and this action rather deteriorates linear cut property. Based on the above findings, the present invention has been completed.

[0014] The easily tearable film of this embodiment will be described below. The easily tearable film of the present embodiment is usually formed from a resin composition for forming an easily tearable film. The resin composition contains a polybutylene terephthalate resin and a polyamide resin, and when the total amount of the polybutylene terephthalate resin and the polyamide resin is 100 parts by mass, the polybutylene terephthalate resin is contained in an amount of 95 to 75 parts by mass, the polyamide resin contains a xylylenediamine-based polyamide resin, and the melt volume rate (MVR) of the polybutylene terephthalate resin measured at 250° C. under a load of 2.16 kg is 5 to 15 cm 3 / 10 min, and the total content of the polyvalent carboxylic acid compound having three or more carboxyl groups bonded to an aromatic ring in one molecule and / or the polyvalent carboxylic acid compound in which two or more of the carboxyl groups bonded to the compound form an anhydride ring is 0 parts by mass or more and less than 0.01 parts by mass relative to 100 parts by mass of the total amount of the polybutylene terephthalate resin and the polyamide resin.

[0015] <Polyamide resin> The resin composition used in the present embodiment contains a polyamide resin (xylylenediamine-based polyamide resin) having diamine constituent units containing 70 mol % or more of xylylenediamine constituent units (preferably xylylenediamine constituent units) and dicarboxylic acid constituent units containing 70 mol % or more of α,ω-linear aliphatic dicarboxylic acid constituent units having 4 to 8 carbon atoms (preferably adipic acid units). By using such a xylylenediamine-based polyamide resin, an easily tearable film with excellent linear cut properties can be obtained.

[0016] The diamine-derived constitutional units of the xylylenediamine-based polyamide resin used in this embodiment are preferably 75 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, and even more preferably 97 mol% or more derived from xylylenediamine. The dicarboxylic acid constitutional units of the xylylenediamine-based polyamide resin are preferably 75 mol% or more, more preferably 75 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, and even more preferably 97 mol% or more derived from α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms. The total amount of the diamine-derived structural units does not exceed 100 mol %, and the total amount of the dicarboxylic acid structural units does not exceed 100 mol %.

[0017] The xylylenediamine is preferably paraxylylenediamine and / or metaxylylenediamine, and preferably contains at least metaxylylenediamine. Specifically, it is preferred that 0 to 100 mol % of the diamine-derived constituent units are meta-xylylenediamine-derived constituent units, and that 0 to 100 mol % of the diamine-derived constituent units are para-xylylenediamine-derived constituent units (however, the total of para-xylylenediamine and meta-xylylenediamine does not exceed 100 mol %), it is more preferred that 50 to 100 mol % of the diamine-derived constituent units are meta-xylylenediamine-derived constituent units, and that 50 to 0 mol % of the diamine-derived constituent units are para-xylylenediamine-derived constituent units, and it is even more preferred that 80 to 100 mol % of the diamine-derived constituent units are meta-xylylenediamine-derived constituent units, and that 20 to 0 mol % of the diamine-derived constituent units are para-xylylenediamine-derived constituent units.

[0018] Diamines other than metaxylylenediamine and paraxylylenediamine that can be used as the raw diamine component of the xylylenediamine-based polyamide resin include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine, 1,3-bis( Examples of the diamines include alicyclic diamines such as bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane; and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenediamine, and bis(aminomethyl)naphthalene. These can be used alone or in combination of two or more.

[0019] Examples of α,ω-linear aliphatic dicarboxylic acids having 4 to 8 carbon atoms that are suitable for use as the raw dicarboxylic acid component of the xylylenediamine-based polyamide resin include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid, and these can be used alone or in combination of two or more. Among these, adipic acid is more preferred because the melting point of the polyamide resin falls within a range suitable for molding.

[0020] Examples of dicarboxylic acid components other than the α,ω-linear aliphatic dicarboxylic acids having 4 to 8 carbon atoms include aliphatic dicarboxylic acids having 9 or more carbon atoms, such as azelaic acid, sebacic acid, and dodecanedioic acid; phthalic acid compounds, such as isophthalic acid, terephthalic acid, and orthophthalic acid; and isomers of naphthalene dicarboxylic acid, such as 1,2-naphthalene dicarboxylic acid, 1,3-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene dicarboxylic acid. These can be used alone or in combination of two or more.

[0021] In addition, the xylylenediamine-based polyamide resin is mainly composed of diamine-derived structural units and dicarboxylic acid structural units, but does not completely exclude other structural units, and may contain lactams such as ε-caprolactam and laurolactam, and structural units derived from aliphatic aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid. Here, the main component means that the total number of diamine-derived structural units and dicarboxylic acid structural units is the largest among all structural units among the structural units constituting the xylylenediamine-based polyamide resin. In this embodiment, the total of diamine-derived structural units and dicarboxylic acid structural units in the xylylenediamine-based polyamide resin preferably accounts for 90% by mass or more of all structural units, more preferably accounts for 95% by mass or more, and even more preferably accounts for 98% by mass or more.

[0022] The melting point of the xylylenediamine-based polyamide resin is preferably 150°C or higher, more preferably 180°C or higher, even more preferably 200°C or higher, and even more preferably 210°C or higher, and is preferably 350°C or lower, more preferably 330°C or lower, even more preferably 300°C or lower, even more preferably 280°C or lower, and even more preferably 260°C or lower. The glass transition temperature of the xylylenediamine-based polyamide resin is preferably 70°C or higher, more preferably 75°C or higher, and even more preferably 80°C or higher, and is preferably 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower. When the resin composition used in the present embodiment contains two or more kinds of xylylenediamine-based polyamide resins, Tm and Tg are each a weighted average value.

[0023] The relative viscosity of the xylylenediamine-based polyamide resin in a 96% sulfuric acid solution measured at 25°C according to JIS K 6920-2 is preferably 3.0 or less, more preferably 2.8 or less, and even more preferably 2.3 or less. By making the relative viscosity equal to or less than the upper limit, the transparency of the film after stretching tends to be improved. The lower limit of the relative viscosity is preferably 1.9 or more, and may be 2.0 or more. By making the relative viscosity equal to or more than the lower limit, the impact resistance of the film tends to be further improved.

[0024] More specifically, the relative viscosity is determined by the following method. Weigh out 0.2 g of polyamide resin and dissolve it in 20 mL of 96% by weight sulfuric acid solution at 25°C with stirring. After complete dissolution, immediately transfer 5 mL of the solution to a Cannon-Fenske viscometer and leave it in a thermostatic bath at 25°C for 10 minutes, then measure the drop time (t) of the solution. Also measure the drop time (t0) of the 96% by weight sulfuric acid solution itself under the same conditions. Calculate the relative viscosity from t and t0 using the following formula. Relative viscosity=t / t0 When the resin composition used in the present embodiment contains two or more kinds of xylylenediamine-based polyamide resins, the weighted average of the relative viscosities of the xylylenediamine-based polyamide resins used is defined as the relative viscosity of the mixture.

[0025] The lower limit of the number average molecular weight (Mn) of the polyamide resin is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 12,000 or more. By setting it to the lower limit or more, the impact resistance of the film tends to be further improved. The upper limit of the Mn is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 25,000 or less, and even more preferably 20,000 or less. By setting it to the upper limit or less, the transparency of the film after stretching tends to be improved. When the resin composition used in the present embodiment contains two or more kinds of xylylenediamine-based polyamide resins, the weighted average of the number average molecular weights of the xylylenediamine-based polyamide resins used is taken as the number average molecular weight of the mixture.

[0026] It is also preferable to use a polyamide resin produced using a biomass raw material (biomass polyamide resin) as the xylylenediamine-based polyamide resin. By using a biomass polyamide resin, it is possible to reduce the environmental load. For xylylenediamine-based polyamide resins, bio-adipic acid can be used as a biomass raw material. Mass balance certified (ISCC PLUS) adipic acid can also be used. Mass balance certification means that the amount of renewable raw materials and bio-raw materials used at each factory or production facility and the amount of products produced or shipped are quantified and guaranteed along with their quality.

[0027] The content of the xylylenediamine-based polyamide resin in the resin composition used in this embodiment is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 18% by mass or more. By making it equal to or more than the lower limit, the linear cut property of the stretched film tends to be improved. The content of the xylylenediamine-based polyamide resin in the resin composition used in this embodiment is preferably 25% by mass or less, more preferably 23% by mass or less, and even more preferably 22% by mass or less. By making it equal to or less than the upper limit, the linear cut property, the maximum strength of the tensile test, and the pinhole resistance tend to be improved. This is because the optimal stretching temperature of the xylylenediamine-based polyamide resin is different from that of the polybutylene terephthalate resin, and if it is made larger than the upper limit, the influence of the difference becomes significant, and stretching defects may easily occur. The resin composition used in the present embodiment may contain only one type of xylylenediamine-based polyamide resin, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0028] The resin composition used in the present embodiment may or may not contain a polyamide resin other than the xylylenediamine-based polyamide resin. The type of polyamide resin other than the xylylenediamine-based polyamide resin is not particularly limited, and it may be either an aliphatic polyamide resin or a semi-aromatic polyamide resin. Examples of the aliphatic polyamide resin include polyamide 6, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, polyamide 612, and polyamide 6 / 66, with polyamide 66 being preferred. The semi-aromatic polyamide resin is composed of a diamine-derived structural unit and a dicarboxylic acid structural unit, and 20 to 80 mol % of the total structural units of the diamine-derived structural unit and the dicarboxylic acid structural unit are structural units containing an aromatic ring. Examples of the semi-aromatic polyamide resin include terephthalic acid-based polyamide resins (polyamide 6T, polyamide 9T, polyamide 10T), polyamide resins synthesized from xylylenediamine and sebacic acid, etc. In particular, one example is blending a polyamide resin synthesized from xylylenediamine and sebacic acid. Since sebacic acid is obtained from plants, the polyamide resin synthesized from xylylenediamine and sebacic acid corresponds to a biomass resin and is preferable from the viewpoint of environmental load.

[0029] The content of the polyamide resin other than the xylylenediamine-based polyamide resin in the resin composition used in this embodiment can be appropriately set according to the application, desired performance, etc., but is preferably 0.5 mass% or more, more preferably 1 mass% or more, even more preferably 1.5 mass% or more, and even more preferably 2 mass% or more. The content of the polyamide resin other than the xylylenediamine-based polyamide resin in the resin composition used in this embodiment is preferably 10 mass% or less, more preferably 7 mass% or less, even more preferably 5 mass% or less, even more preferably 3 mass% or less, even more preferably 1 mass% or less, and may be 0.1 mass% or less. By setting it to the upper limit value or less, the mechanical strength of the molded product tends to be maintained. The resin composition used in the present embodiment may contain only one type of polyamide resin other than the xylylenediamine-based polyamide resin, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0030] <Polybutylene terephthalate resin> The polybutylene terephthalate resin used in this embodiment has a melt volume rate (MVR) of 5 to 15 cm3 measured at 250°C under a load of 2.16 kg. 3 / 10min. By setting the MVR of the polybutylene terephthalate resin to the lower limit or more, the load on the extruder when extruding the stretched raw sheet tends to be reduced. Also, by setting the MVR of the polybutylene terephthalate resin to the upper limit or less, unevenness in the width and thickness of the film tends to be further reduced. The MVR of the polybutylene terephthalate resin is 6 cm 3 / 10min or more is preferable, and 8cm 3 / 10min or more is more preferable, and 13cm 3 / 10min or less is preferable, and 12cm 3 / 10min or less is more preferable, and 11cm 3 / 10min or less is more preferable, and 10cm 3 It is more preferable that the time is 10 min or less. When two or more types of polybutylene terephthalate resin are contained, the MVR is the mixture.

[0031] The polybutylene terephthalate resin used in the resin composition used in this embodiment is a polyester resin having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded, and includes, in addition to polybutylene terephthalate resin (homopolymer), a polybutylene terephthalate copolymer containing other copolymerization components other than terephthalic acid units and 1,4-butanediol units, and a mixture of a homopolymer and a polybutylene terephthalate copolymer. When the polybutylene terephthalate resin is a copolymer, the copolymerization amount is 1 mol% or more and less than 50 mol% of all units of the polybutylene terephthalate resin. In particular, the copolymerization amount is preferably 2 mol% or more and less than 50 mol%, more preferably 3 to 40 mol%, and further preferably 5 to 20 mol%.

[0032] The polybutylene terephthalate resin may contain one or more types of dicarboxylic acid units other than terephthalic acid. Specific examples of other dicarboxylic acids include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis(4,4'-carboxyphenyl)methane, anthracenedicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid; and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and dimer acid. In the polybutylene terephthalate resin used in the present embodiment, terephthalic acid units preferably account for 80 mol % or more of all dicarboxylic acid units, more preferably 90 mol % or more, even more preferably 95 mol % or more, and may be 99 mol % or more. The upper limit may be 100 mol %.

[0033] The diol unit may contain one or more other diol units in addition to 1,4-butanediol. Specific examples of other diol units include aliphatic or alicyclic diols having 2 to 20 carbon atoms, bisphenol derivatives, etc. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4'-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, ethylene oxide adduct diol of bisphenol A, etc. In addition to the above-mentioned bifunctional monomers, a small amount of a trifunctional monomer such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, trimethylolpropane, etc., can be used in combination to introduce a branched structure, or a monofunctional compound such as a fatty acid, etc., can be used in combination to adjust the molecular weight. In the polybutylene terephthalate resin used in the present embodiment, 1,4-butanediol units preferably account for 80 mol % or more of all diol units, more preferably 90 mol % or more, even more preferably 95 mol % or more, and may even be 99 mol % or more. The upper limit may be 100 mol %.

[0034] In the polybutylene terephthalate resin used in the present embodiment, terephthalic acid units and 1,4-butanediol units preferably account for 90 mol % or more of all units excluding terminal groups, more preferably 95 mol % or more, even more preferably 98 mol % or more, and even more preferably 99 mol % or more. The upper limit may be 100 mol %.

[0035] The amount of terminal carboxyl groups in the polybutylene terephthalate resin may be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. By setting it to the above upper limit or less, the alkali resistance and hydrolysis resistance tend to be improved. The lower limit of the amount of terminal carboxyl groups is not particularly set, but considering the productivity of the production of the polybutylene terephthalate resin, it is preferably 5 eq / ton or more.

[0036] The amount of terminal carboxyl groups in the polybutylene terephthalate resin is a value measured by dissolving 0.5 g of the polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating it with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. The amount of terminal carboxyl groups can be adjusted by any conventionally known method, such as adjusting the polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and the pressure reduction method, or by reacting a terminal blocking agent.

[0037] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 dL / g or more, more preferably 0.6 dL / g or more. The intrinsic viscosity is preferably 2 dL / g or less, more preferably 1.5 dL / g or less, even more preferably 1.4 dL / g or less, even more preferably 1.3 dL / g or less, even more preferably 1.26 dL / g or less, and may be 1.0 dL / g or less, or 0.9 dL / g or less. By making the intrinsic viscosity equal to or less than the upper limit, moldability tends to be further improved. When the resin composition used in the present embodiment contains two or more types of polybutylene terephthalate resins, the intrinsic viscosity is the intrinsic viscosity of the mixture. Resin pellets were dissolved in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (mass ratio 1 / 1) by stirring at 110°C for 1 hour to a concentration of 1.00 g / dL. The solution was then cooled to 30°C. The time it took for the sample solution and the solvent alone to fall at 30°C was measured using a fully automatic solution viscometer, and the intrinsic viscosity was calculated using the following formula (A). Intrinsic viscosity=((1+4K H η sp ) 0.5 -1) / (2K H C) …(A) Here, η sp = η / η0-1, where η is the time it takes for the sample solution to fall, η0 is the time it takes for the solvent alone to fall, C is the concentration of the sample solution (g / dL), and K H is Huggins' constant. K H was set to 0.33. The fully automatic solution viscometer used was a product of Shibayama Scientific Co., Ltd.

[0038] The glass transition temperature of the polybutylene terephthalate resin is preferably 35°C or higher, more preferably 40°C or higher, and even more preferably 45°C or higher, and is preferably 65°C or lower, more preferably 60°C or lower, and even more preferably 55°C or lower. When the resin composition used in the present embodiment contains two or more kinds of polybutylene terephthalate resins, Tg is the weighted average value of the respective polybutylene terephthalate resins.

[0039] Polybutylene terephthalate resin can be produced by batch or continuous melt polymerization of a dicarboxylic acid component mainly composed of terephthalic acid or an ester derivative thereof and a diol component mainly composed of 1,4-butanediol. In addition, after producing a low molecular weight polybutylene terephthalate resin by melt polymerization, the degree of polymerization (or molecular weight) can be increased to a desired value by further solid-phase polymerization under a nitrogen gas flow or reduced pressure. The polybutylene terephthalate resin is preferably one obtained by a production method in which a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of 1,4-butanediol are melt-polycondensed in a continuous or batch manner.

[0040] It is also preferable to use a polybutylene terephthalate resin produced from biomass as a raw material (biomass polybutylene terephthalate resin) as the polybutylene terephthalate resin. By using a biomass raw material, it is possible to reduce the environmental load.

[0041] <Blend ratio> The film contains polybutylene terephthalate resin and polyamide resin, and when the total amount of the polybutylene terephthalate resin and the polyamide resin is 100 parts by mass, the content of the polybutylene terephthalate resin is 75 parts by mass or more, preferably more than 75 parts by mass, more preferably 76 parts by mass or more, even more preferably 77 parts by mass or more, even more preferably 78 parts by mass or more, and even more preferably 79 parts by mass or more. By making it equal to or more than the lower limit, the pinhole resistance of the film tends to be further improved. In addition, when the total amount of the polybutylene terephthalate resin and the polyamide resin is 100 parts by mass, the content of the polybutylene terephthalate resin is 95 parts by mass or less, preferably 93 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 89 parts by mass or less, even more preferably 85 parts by mass or less, and even more preferably 82 parts by mass or less. By making it equal to or less than the upper limit, the linear cut property and oxygen barrier property tend to be further improved.

[0042] The total amount of the polybutylene terephthalate resin and the xylylene diamine-based polyamide resin in the resin composition used in this embodiment is preferably 90% by mass or more, more preferably 93% by mass or more, even more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more in 100% by mass of the resin composition. The total amount of the polybutylene terephthalate resin and the xylylene diamine-based polyamide resin in 100% by mass of the resin composition may be 100% by mass. The resin composition used in the present embodiment may contain only one type of polybutylene terephthalate resin and one type of xylylene diamine-based polyamide resin, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0043] <Other ingredients> In the resin composition used in the present embodiment, the total content of the polycarboxylic acid compound in which three or more carboxyl groups are bonded to an aromatic ring in one molecule and / or the polycarboxylic acid compound in which two or more of the carboxyl groups bonded to the compound form an anhydride ring is 0 parts by mass or more and less than 0.01 parts by mass, and more preferably less than 0.001 parts by mass, relative to the total amount of 100 parts by mass of the polybutylene terephthalate resin and the polyamide resin. By adopting such a configuration, the straight line cutting property can be effectively improved. Specific examples of the compounds can be referred to the description in JP-A-2000-302952, the contents of which are incorporated herein by reference.

[0044] The resin composition used in the present embodiment may also contain other components within the scope of the present invention. Specifically, additives such as thermoplastic resins other than polybutylene terephthalate resins and polyamide resins, fillers, matting agents, heat stabilizers, weather stabilizers, antioxidants, UV absorbers, plasticizers, flame retardants, antistatic agents, coloring inhibitors, gelling inhibitors, impact modifiers, lubricants, colorants, and conductive additives can be mentioned. Each of these additives may be one type or two or more types. For details of these, please refer to the descriptions in paragraphs 0130 to 0155 of Japanese Patent No. 4894982 and the descriptions in paragraphs 0047 to 0103 of International Publication No. 2021 / 241471, the contents of which are incorporated herein by reference. When the resin composition used in the present embodiment contains components other than the polybutylene terephthalate resin and the polyamide resin, the total amount thereof is preferably 0 to 5 mass%, more preferably 0 to 3 mass%, and may be 0 to 1 mass%. The other components may be contained in only one type, or in two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0045] <Characteristics of easily tearable film> The easily tearable film of this embodiment has an oxygen permeability coefficient of 3.0 cc mm / (m 2·day·atm) or less, or even 2.8cc·mm / (m 2 ·day·atm) or less, especially 2.5cc·mm / (m 2 The lower limit of the oxygen permeability coefficient at 23°C and a relative humidity of 60% can be 0cc mm / (m 2 ·day·atm) is preferable, but 0.1cc·mm / (m 2 ·day·atm) or more can fully meet the required performance.

[0046] In the case of an unstretched film, the tearable film of the present embodiment has a thickness of preferably 40 μm or more, more preferably 60 μm or more, even more preferably 80 μm or more, even more preferably 100 μm or more, and even more preferably 120 μm or more. By making the thickness equal to or greater than the lower limit, the strength of the film tends to be improved. In addition, the tearable film of the present embodiment has a thickness of preferably 400 μm or less, more preferably 350 μm or less, even more preferably 300 μm or less, even more preferably 250 μm or less, and even more preferably 200 μm or less. By making the thickness equal to or less than the upper limit, the linear cuttability tends to be improved.

[0047] In the case of a stretched film, the tearable film of the present embodiment has a thickness of preferably 5 μm or more, more preferably 8 μm or more, even more preferably 10 μm or more, even more preferably 12 μm or more, and even more preferably 13 μm or more. By making the thickness equal to or greater than the lower limit, the strength of the film tends to be improved. In addition, the tearable film of the present embodiment has a thickness of preferably 35 μm or less, more preferably 30 μm or less, even more preferably 25 μm or less, even more preferably 20 μm or less, and even more preferably 18 μm or less. By making the thickness equal to or less than the upper limit, the transparency of the film tends to be improved.

[0048] <Method of manufacturing easily tearable film> The easily tearable film of the present embodiment is produced by a known film production method. The tearable film of the present embodiment may or may not be stretched, but is preferably stretched. The stretching may be uniaxial or biaxial, but is preferably biaxial. In the case of uniaxial stretching, the stretching ratio is preferably 1.1 times or more, more preferably 1.8 times or more, and even more preferably 2.5 times or more. In the case of uniaxial stretching, the stretching ratio is preferably 5.0 times or less, more preferably 4.0 times or less, and even more preferably 3.5 times or less. In the case of biaxial stretching, it is preferable that the film is stretched at the above stretching ratio in the TD direction and the MD direction, respectively. In the case of biaxial stretching, the total stretching ratio obtained by multiplying the stretching ratios in the TD direction and the MD direction is preferably 1.2 times or more, more preferably 3.2 times or more, and even more preferably 6.3 times or more. In the case of biaxial stretching, the total stretch ratio obtained by multiplying the stretch ratios in the TD and MD directions is preferably 25 times or less, more preferably 16 times or less, and even more preferably 12.3 times or less.

[0049] The stretching temperature is preferably higher than the glass transition temperature of the polybutylene terephthalate resin and not higher than the glass transition temperature of the xylylene diamine polyamide resin + 40° C. More preferably, it is higher than the glass transition temperature of the polybutylene terephthalate resin + 10° C. and not higher than the glass transition temperature of the xylylene diamine polyamide resin + 25° C. The stretching temperature means the temperature of the film when the film is stretched. For details of the manufacturing method of the stretched film, the description in International Publication No. 2017 / 010390 can be referred to.

[0050] The easily tearable film of the present embodiment can be used as a single layer film. The monolayer film can be suitably used for wrapping, pouches of various shapes, container lids, and packaging containers such as bottles, cups, trays, tubes, etc. The details of the containers will be described later.

[0051] This embodiment also discloses a multilayer film having the easily tearable film of this embodiment. Specifically, the multilayer film may include a layer of a polyester resin other than polybutylene terephthalate resin, a layer of a polyolefin resin, or the like. These layers are preferably bonded together with an adhesive. The adhesive layer is preferably an adhesive for dry lamination having adhesive properties. Examples of the adhesive for dry lamination include a one-liquid type that uses a urethane adhesive having an isocyanate group alone, and a two-liquid type that uses a mixture of a base agent having a hydroxyl group and a curing agent having an isocyanate group, and the two-liquid type urethane adhesive is particularly preferred. The thickness of the adhesive layer is preferably 2 to 30 μm, more preferably 3 to 20 μm, and even more preferably 4 to 10 μm, from the viewpoint of ensuring the mechanical strength of the multilayer film while exerting a practical adhesive strength. The multilayer film can be suitably used for wrapping, pouches of various shapes, container lids, bottles, cups, trays, tubes, and other packaging containers. The containers will be described in detail below.

[0052] The stretched laminated film of the present embodiment may have a sealant layer disposed on one or both surfaces. As the film material constituting the sealant layer, various flexible polymer films having heat sealability can be used, and may be appropriately selected from them according to the purpose and use. When considering the development of good heat sealability, it is preferable to use low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polybutene, copolymers thereof, ionomer resins, ethylene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, modified polyolefin resins, and mixtures thereof. Among them, it is preferable to use low density polyethylene, high density polyethylene, linear low density polyethylene, and polypropylene. The surfaces of these films may be subjected to various surface treatments such as flame treatment and corona discharge treatment. The thickness of the sealant layer is preferably in the range of 5 to 300 μm, more preferably 5 to 100 μm, and even more preferably 5 to 80 μm.

[0053] Furthermore, a packaging material having the easily tearable film or the multilayer film of the present embodiment is disclosed. The packaging material of the present embodiment can be preferably used for wraps, or containers such as pouches of various shapes, container lids, bottles, cups, trays, and tubes.

[0054] The container (preferably a multi-layer container) can store and preserve various items whose contents need to be made visible to increase customers' purchasing motivation. Examples include processed seafood products, processed livestock products, rice, and liquid foods. In particular, it is suitable for preserving foods that require high heat sterilization temperatures of 100°C or higher and are susceptible to the effects of oxygen. For details of these, please refer to the descriptions in paragraphs 0032 to 0035 of JP 2011-37199 A, the contents of which are incorporated herein by reference. EXAMPLES

[0055] The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0056] 1. Raw materials The following raw materials were used: <Polybutylene terephthalate resin> NOVADURAN (registered trademark): 5020, manufactured by Mitsubishi Chemical Corporation, MVR (250°C / 2.16kg) 10cm 3 / 10min NOVADURAN: 5026, Mitsubishi Chemical, MVR (250℃ / 2.16kg) 8cm 3 / 10min NOVADURAN: 5010R5, Mitsubishi Chemical, MVR (250℃ / 2.16kg) 21cm 3 / 10min <Pyromellitic anhydride> Pyromellitic anhydride (PMDA): Tokyo Chemical Industry Co., Ltd.

[0057] <Xylylenediamine-based polyamide resin> Polyamide resin A 0.3 g of sodium hypophosphite monohydrate and 0.1 g of sodium acetate were added to 8.9 kg of adipic acid, and the mixture was heated and melted in a reaction vessel at 170°C under 0.1 MPaA. While stirring the contents, 8.3 kg of metaxylylenediamine was gradually dropped over 2 hours to raise the temperature to 250°C. After the temperature increase, the pressure was gradually lowered to 0.08 MPaA over 1 hour and maintained for 0.5 hours. After the reaction was completed, the contents were taken out in a strand shape and pelletized with a pelletizer. The obtained pellets were charged into a tumbler (rotary vacuum chamber) with a heat medium heating jacket and heated at 200°C for 2 hours under reduced pressure (0.5 to 10 Torr), and the obtained pellets were solid-phase polymerized to obtain polyamide resin A (MXD6, melting point: 237°C, relative viscosity: 2.7, number average molecular weight (Mn): 26500).

[0058] Polyamide resin B 7.8g of sodium hypophosphite monohydrate and 4.0g of sodium acetate were added to 8.9kg of adipic acid, and the mixture was heated and melted in a reaction vessel at 170°C under 0.1MPaA. Then, 8.2kg of metaxylylenediamine was gradually dropped over 2 hours while stirring the contents, and the temperature was raised to 250°C. After the temperature was raised, the pressure was gradually lowered to 0.08MPaA over 1 hour and maintained for 0.5 hours. After the reaction was completed, the contents were taken out in a strand shape and pelletized with a pelletizer. The obtained pellets were charged into a tumbler (rotary vacuum chamber) with a heat medium heating jacket, and heated at 180°C for 1 hour under reduced pressure (0.5 to 10 Torr), to carry out solid-state polymerization of the obtained pellets, and polyamide resin B (MXD6, melting point: 237°C, relative viscosity: 2.1, number average molecular weight (Mn): 16000) was obtained.

[0059] 2. Examples 1 to 4 and Comparative Examples 1 to 4 A tearable film was produced using a single-screw extruder with a diameter of 25 mm and an L / D ratio of 25 (PTM25, manufactured by Plastics Engineering Research Institute Co., Ltd.), a head equipped with a 600 mesh filter, a film extruder consisting of a T-die, a cooling roll, a take-up device equipped with a winding machine, etc. The extruder was set to 270°C, the die temperature to 270°C, the cooling roll temperature to 30°C, and the periphery of the cooling roll was cooled by blowing air with a blower, and the polybutylene terephthalate resin and the polyamide resin shown in Table 1 were dry-blended. Note that, for Comparative Example 4, pyromellitic anhydride was further dry-blended. The obtained dry blend was put into an extruder, the screw speed was set to 50 rpm, and the resin composition was extruded into a film shape, and the take-up speed was adjusted to obtain an unstretched film having a width of 15 cm and a thickness of 145 μm. The obtained unstretched film was held for 10 seconds in a clip-type simultaneous biaxial stretching machine at a preheating blowing temperature of 85°C and a preheating furnace temperature of 90°C, after which it was stretched 3.0 times in the longitudinal direction and 3.0 times in the transverse direction, and then heat-set in a tenter oven at 200°C for 30 seconds. The linear cuttability of the obtained biaxially stretched film (easily tearable film, thickness 15 μm) was evaluated. The results are shown in Table 1.

[0060] <Film formation stability> The film formation stability was visually evaluated as follows. The evaluation was performed by five experts and judged by majority vote. A: Stable film formation was achieved B: Other than A (film could not be produced stably, film could not be produced at all, etc.) The films that were rated A for film formation stability were evaluated as follows.

[0061] <Tensile test> The stretched film obtained above was stored in an environment of 23°C and 50% relative humidity for one week, and then a tensile test was performed in the MD direction of the film according to JIS K 7127 using a 10 mm wide strip with a chuck distance of 50 mm and a tensile speed of 50 mm / min.

[0062] <Pinhole resistance> The stretched film obtained above was twisted 360 degrees 500 times using a Gelbo Flex Tester (manufactured by Rigaku Kogyosha) to measure the number of pinholes that occurred. The fewer the number of pinholes, the higher the pinhole resistance.

[0063] <Oxygen permeability coefficient> The oxygen permeability coefficient of the easily tearable films (unstretched film and stretched film) obtained above was measured in accordance with ASTM-D3985 under an atmosphere of 23° C. and a relative humidity (RH) of 60% by the isobaric method. The oxygen permeability coefficient was measured using an oxygen permeability coefficient measuring device (manufactured by MOCON, product name: "OX-TRAN (registered trademark) 2 / 21").

[0064] <Evaluation method for straight line cutting ability> A film with linear cuttability has a property of easily tearing in the MD direction even if it is torn in a direction slightly away (shifted) from the MD direction. On the other hand, even if a film has a property of being easily torn, if the film has low linear cuttability, when it is torn in a direction slightly away from the MD direction, it tends to tear in the direction of the tear, not in the MD direction. In addition, a film with very low linear cuttability tends to have an unstable tear direction to begin with. As shown in Figure 1, a straight line (line A) was drawn in the MD direction of the biaxially stretched film, and two straight lines (line B, line C) were drawn in the TD direction. The distance between the two straight lines (line B, line C) in the TD direction was 20 cm. The intersection of line A and line B was intersection b, and the intersection of line A and line C was intersection c. The position shifted 1 cm in the TD direction from intersection c was point d (i.e., the distance between c and d was 1 cm). A straight line (line D) passing through intersection b and point d was drawn. When the film was torn in the direction from intersection b to point d, the average value of the shift width (unit: mm) in the TD direction from intersection c for 10 times was taken as the straight cut property. Note that Figure 1 is an image and is not to scale.

[0065] <Content visibility> The biaxially stretched film obtained above was placed on a piece of paper on which characters were printed, and the legibility of the characters was evaluated. S: The characters were clearly visible and legible. A: The letters were difficult to see, but were clearly legible. B: The text was legible but not clear. C: I couldn't read the letters.

[0066] [Table 1]

[0067] As is clear from the above results, the easily tearable films of the present embodiment were excellent in film formation stability and linear cutability (Examples 1 to 4). In contrast, when no xylylenediamine-based polyamide resin was blended (Comparative Example 1), when a large amount of xylylenediamine-based polyamide resin was blended (Comparative Example 3), or when pyromellitic anhydride was blended (Comparative Example 4), straight line cutting properties were not achieved. In addition, the MVR of polybutylene terephthalate resin is 5 to 15 cm 3 When the temperature was outside the range of 10 min / 10 min (Comparative Example 2), the film formation stability was poor. Note that, in Comparative Example 2, the film formation stability was very poor, so other evaluations were not performed. In Comparative Example 3, although the film could be formed into a film shape, stable stretching was not possible.

Claims

1. It contains polybutylene terephthalate resin and polyamide resin, A tearable film formed from a resin composition containing 95 to 75 parts by mass of polybutylene terephthalate resin, where the total amount of polybutylene terephthalate resin and polyamide resin is 100 parts by mass. The polyamide resin comprises a polyamide resin having diamine structural units containing 70 mol% or more xylylenediamine structural units and dicarboxylic acid structural units containing 70 mol% or more α,ω-linear aliphatic dicarboxylic acid structural units having 4 to 8 carbon atoms. The melt volume rate (MVR) of polybutylene terephthalate resin measured at 250°C and a 2.16 kg load was 5 to 15 cm³. ３ / 10min, The total content of polycarboxylic acid compounds having three or more carboxyl groups bonded to an aromatic ring in one molecule, and / or polycarboxylic acid compounds in which two or more of the carboxyl groups bonded to said compounds form an anhydrous ring, is 0 parts by mass or more and less than 0.01 parts by mass, per 100 parts by mass of the total amount of polybutylene terephthalate resin and polyamide resin. Tear-resistant film.

2. The tearable film according to claim 1, wherein 70 mol% or more of the dicarboxylic acid constituent units are adipic acid constituent units.

3. The melt volume rate (MVR) of polybutylene terephthalate resin measured at 250°C and a 2.16 kg load was 8–15 cm³. ３ The tear-resistant film according to claim 1 or 2, wherein the length is / 10 min.

4. The tear-resistant film according to claim 1 or 2, wherein the relative viscosity of a 96% sulfuric acid solution of polyamide resin, measured at 25°C according to JIS K 6920-2, is 1.9 to 2.

3.

5. More than 70 mol% of the aforementioned dicarboxylic acid constituent units are derived from adipic acid. The melt volume rate (MVR) of the aforementioned polybutylene terephthalate resin, measured at 250°C and a 2.16 kg load, was 8 to 15 cm³. ３ / 10min, The tearable film according to claim 1, wherein the relative viscosity of a 96% sulfuric acid solution of the polyamide resin, measured at 25°C according to JIS K 6920-2, is 1.9 to 2.

3.

6. The tearable film according to claim 1 or 2, wherein the tearable film is a stretched film.

7. 70 mol% or more of the dicarboxylic acid constituent units are derived from adipic acid, The melt volume rate (MVR) of the aforementioned polybutylene terephthalate resin, measured at 250°C and a 2.16 kg load, was 8 to 15 cm³ / 10 min. The relative viscosity of the polyamide resin in a 96% sulfuric acid solution, measured at 25°C according to JIS K 6920-2, is 1.9 to 2.

3. The tearable film according to claim 1, wherein the tearable film is a stretched film.

8. A multilayer film having the tearable film according to claim 1, 2, or 7.

9. A packaging material having a tearable film according to claim 1, 2, or 7.

10. A container having the easily tearable film according to claim 1, 2, or 7.

11. It contains polybutylene terephthalate resin and polyamide resin, A resin composition for forming easily tearable films, wherein the total amount of polybutylene terephthalate resin and polyamide resin is 100 parts by mass, and the composition contains 95 to 75 parts by mass of polybutylene terephthalate resin, The polyamide resin comprises a polyamide resin having diamine structural units containing 70 mol% or more xylylenediamine structural units and dicarboxylic acid structural units containing 70 mol% or more α,ω-linear aliphatic dicarboxylic acid structural units having 4 to 8 carbon atoms. The melt volume rate (MVR) of polybutylene terephthalate resin measured at 250°C and a 2.16 kg load was 5 to 15 cm³. ３ / 10min, The total content of polycarboxylic acid compounds having three or more carboxyl groups bonded to an aromatic ring in one molecule, and / or polycarboxylic acid compounds in which two or more of the carboxyl groups bonded to said compounds form an anhydrous ring, is 0 parts by mass or more and less than 0.01 parts by mass, per 100 parts by mass of the total amount of polybutylene terephthalate resin and polyamide resin. Resin composition.

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