JP2006028289A - Easily tearable biaxially oriented polyamide film and its application - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially oriented polyamide film that has excellent transparency and flexural fatigue resistance and is extremely excellent in easy tearability upon tearing the film in the longitudinal direction. <P>SOLUTION: The easily tearable biaxially oriented polyamide film is made of the polyamide composition comprising 65-95 wt% of an aliphatic polyamide (A) and 35-5 wt% of a semi-aromatic polyamide (B) consisting of a diamine unit comprising 1,9-nonanediamine and/or 2-methyl-1,8-octadiamine unit to the total diamine unit, and a diamine unit having the same carbon number as that of the repetition structure unit of the aliphatic polyamide (A) in an amount of ≥60 mol% to the total diamine unit, and a dicarboxylic acid unit containing 60 mol% or more telephthalic acid to the total dicarboxylic acid unit. The easily tearable biaxially oriented polyamide film satisfies ¾Tm(B)-Tm(A)¾<40°C when the melting point of the aliphatic polyamide(A) is Tm(A) and the melting point of the semi-aromatic polyamide is TM(B). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention comprises a polyamide composition containing an aliphatic polyamide and a specific semi-aromatic polyamide, and is excellent in straightness (hereinafter referred to as easy tearability) when tearing in the film longitudinal (MD) direction. The present invention relates to a biaxially stretched polyamide film having excellent transparency and bending fatigue resistance.

  Many plastic film packaging bags are used for packaging foods, pharmaceuticals, miscellaneous goods, etc., and a packaging bag in which two or more layers of biaxially stretched plastic film and heat-sealable unstretched plastic film are laminated. Is widely used. Especially in food packaging fields where bending fatigue resistance, impact resistance, drop-off bag resistance, etc. are required, the tenter simultaneous biaxial stretching method, the tenter sequential biaxial stretching method, the tubular method, etc. are used. A high-strength biaxially stretched polyamide film manufactured in this manner is used.

  By the way, a product packaged with a biaxially stretched polyamide film needs to be opened at the time of use, and is generally often torn by hand when opened. Therefore, the demand for easy tearability is also increasing. There is a case where a notch is added to the heat seal portion as a device for improving the openability by hand. However, when tearing from this notch, a phenomenon that does not tear linearly in the longitudinal or lateral direction of the packaging bag often occurs. Also, if it is forcibly torn, it tears diagonally, and not only the contents are scattered and wasted at the same time as opening, but it also stains clothes etc. especially when the contents are liquid, semi-fluid or powdery Accidents are easy to happen.

  As a method for improving easy tearability, there is a method in which a uniaxially stretched polyolefin film is laminated as an intermediate layer. For example, a three-layer laminate film of biaxially stretched polyamide film / uniaxially stretched polyolefin film / non-oriented polyolefin film can be mentioned. However, although the easy tearability in the stretching direction of this uniaxially stretched film is improved, since it becomes a laminated structure in which a new intermediate layer is provided only for easy tearability improvement, problems such as high cost remain, Applications were limited.

  In order to improve the easy tearability of the biaxially stretched polyamide film, a method of changing the longitudinal and lateral stretch ratios for the biaxially stretched film, etc., a method of adding a polyolefin resin to the polyamide resin, and a method for forming this into a film are proposed. Has been. In the method of changing the draw ratio, the tearability is insufficient, and in order to improve the easy tearability, when the longitudinal and transverse stretch ratio is increased, good physical properties such as the strength of the biaxially stretched film are sacrificed. Will do. Moreover, when the polyolefin resin is added, the transparency of the polyamide film is inevitably lowered.

  In recent years, as an easy tear film, a biaxially stretched film composed of a mixed polyamide obtained by mixing polymetaxylylene adipamide (polyamide MXD6) with polycaprolactam (polyamide 6) and a laminate film thereof have been proposed (Patent Document 1, (See Patent Document 2 and Patent Document 3). However, in this technique, when the ratio of polyamide MXD6 is increased in order to improve easy tearability, there is a problem that the bending fatigue resistance of the film is lowered, and in particular, the frequency of occurrence of pinholes due to bending fatigue is high. Further, as a means for solving the bending fatigue resistance of the film, a biaxially stretched polyamide film mainly composed of polyamide 6 and a mixture of aliphatic polyamides satisfying a specific surface tension condition other than polyamide 6 has been proposed. (See Patent Document 4). However, the addition of a specific aliphatic polyamide is effective in improving bending fatigue resistance, but is not sufficient for easy tearing. In order to improve easy tearing, an aliphatic polyamide other than polyamide 6 is used. When the blending amount is increased, the transparency is lowered, and it is difficult to achieve both easy tearability and transparency of the film.

Japanese Patent Laid-Open No. 5-220837 Japanese Patent Laid-Open No. 5-200958 JP-A-7-1113015 JP-A-8-47972

  In view of such circumstances, the present invention intends to provide a biaxially stretched polyamide film having excellent transparency and bending fatigue resistance, and extremely excellent tearability when tearing in the longitudinal direction of the film. is there.

  As a result of intensive studies to solve such problems, the present inventors have found that a biaxially stretched polyamide film comprising a polyamide composition comprising an aliphatic polyamide and a specific semi-aromatic polyamide is torn in the longitudinal direction. As a result, the present inventors have found that it has excellent balance of performance such as bending fatigue resistance and transparency as well as easy tearability.

That is, the present invention
(A) 65-95% by weight of aliphatic polyamide and (B) total diamine units, (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine units, and (B3) other than (b1) and (b2) satisfying the condition of the formula (1) (b3) a diamine unit containing 60 mol% or more of an aliphatic diamine unit, and a terephthalic acid unit relative to all dicarboxylic acid units Is a biaxially stretched polyamide film comprising a polyamide composition comprising 35 to 5% by weight of a semi-aromatic polyamide composed of a dicarboxylic acid unit containing 60 mol% or more, and satisfying the condition of the following formula (2) An easily tearable biaxially stretched polyamide film is provided.
[CH ₂ ] / [NHCO] -2 ≦ n ≦ [CH ₂ ] / [NHCO] +4 (1)
(In the formula (1), [CH ₂ ] and [NHCO] represent the number of methylene groups and the number of amide groups in the (A) aliphatic polyamide, respectively.)
| Tm (B) -Tm (A) | <50 ° C. (2)
(In Formula (2), Tm (A) and Tm (B) represent the melting points of (A) aliphatic polyamide and (B) semi-aromatic polyamide, respectively).

  In a preferred embodiment, (A) the aliphatic polyamide is at least one homopolymer or copolymer selected from the group consisting of polycaprolactam (polyamide 6) and polyhexamethylene adipamide (polyamide 66). , (B) diamine unit of semi-aromatic polyamide, (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine unit, and carbon number satisfying the condition of formula (1) The ratio with (b3) aliphatic diamine units other than (b1) and (b2) having n is ((b1) + (b2)) :( b3) = 30: 70 to 90:10 (mol%) This is an easily tearable biaxially stretched polyamide film.

  The easily tearable biaxially stretched polyamide film of the present invention has excellent transparency and bending fatigue resistance, and is extremely excellent in tearability when tearing in the longitudinal direction of the film. Furthermore, also in the laminated film and packaging bag body which use the easily tearable biaxially stretched polyamide film of this invention, favorable tearability is shown. Therefore, it is useful as a film for packaging bags for foods such as soups, jams, retort pouches, medical products, medicines, daily necessities, toiletries and the like.

Hereinafter, the present invention will be described in detail.
The easily tearable biaxially stretched polyamide film in the present invention comprises (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1, based on (A) aliphatic polyamide and (B) all diamine units. A diamine unit containing 60 mol% or more of an (b3) aliphatic diamine unit other than (b1) and (b2) having an n-octanediamine unit and a carbon number n satisfying the condition of the following formula (1): It consists of the raw material polyamide composition containing the semi-aromatic polyamide which consists of the dicarboxylic acid unit which contains 60 mol% or more of terephthalic acid units with respect to a unit (it may be hereafter called a raw material polyamide composition).
[CH ₂ ] / [NHCO] -2 ≦ n ≦ [CH ₂ ] / [NHCO] +4 (1)
(In the formula (1), [CH ₂ ] and [NHCO] represent the number of methylene groups and the number of amide groups in the (A) aliphatic polyamide, respectively.)
The (A) aliphatic polyamide in the raw material polyamide composition refers to a polyamide comprising an amide bond (—NHCO—) in the main chain and comprising an aliphatic polyamide forming unit. (A) Aliphatic polyamide is polymerized by a known method such as melt polymerization, solution polymerization or solid phase polymerization using lactam, aminocarboxylic acid, or nylon salt composed of aliphatic diamine and aliphatic dicarboxylic acid, or Obtained by copolymerization.

  Examples of lactam include ε-caprolactam, enantolactam, undecane lactam, dodecane lactam, α-pyrrolidone, α-piperidone and the like, and aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11- Examples thereof include aminoundecanoic acid and 12-aminododecanoic acid.

  Examples of the aliphatic diamine constituting the nylon salt include ethylenediamine, 1,3-propylenediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-peptanediamine, , 8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1, 15-pentadecanediamine, 1,16-hexadecanediamine, 1,17-heptadecanediamine, 1,18-octadecanediamine, 1,19-nonadecanediamine, 1,20-eicosanediamine, 2 / 3-methyl-1 , 5-pentanediamine, 2-methyl-1,8-octanediamine, 2,2,4 2,4,4-trimethylhexamethylene diamine, can be mentioned 5-methyl-1,9-nonanediamine or the like.

  Examples of the aliphatic dicarboxylic acid constituting the nylon salt include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, pentadecanedicarboxylic acid, hexadecanedicarboxylic acid. Examples include acid, octadecanedicarboxylic acid, eicosanedicarboxylic acid and the like.

  (A) As the aliphatic polyamide, polycaproamide (polyamide 6), polyundecanamide (polyamide 11), polydodecanamide (polyamide 12), polyethylene adipamide (polyamide 26), polytetramethylene adipamide (polyamide) 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene azelamide (polyamide 69), polyhexamethylene sebamide (polyamide 610), polyhexamethylene undecamide (polyamide 611), polyhexamethylene dodeca Polyamide (polyamide 612), polynonamethylene adipamide (polyamide 96), polynonamethylene azelamide (polyamide 99), polynonamethylene sebamide (polyamide 910), polynonamethylene undecamide (polyamide 91) ), Polynonamethylene dodecamide (polyamide 912), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212) and other homopolymers, and co-polymerization using several raw material monomers forming these A coalescence etc. can be mentioned.

  Among these, polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), polyhexamethylene dodecane (polyamide 612), polyundecanamide (polyamide 11), polydodecanamide (polyamide 12) and these A copolymer using several kinds of raw material monomers to be formed is preferable. In particular, a homopolymer of polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), and a copolymer using raw material monomers forming these are preferable.

The (B) semi-aromatic polyamide in the raw material polyamide composition used in the present invention comprises (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8- (B3) Aliphatic diamine units other than (b1) and (b2) (b3) other than (b1) and (b2) (b3) )) Aliphatic diamine unit ")) and a dicarboxylic acid unit containing 60 mol% or more of terephthalic acid units with respect to all dicarboxylic acid units (hereinafter referred to as ( B) Sometimes referred to as semi-aromatic polyamide).
[CH ₂ ] / [NHCO] -2 ≦ n ≦ [CH ₂ ] / [NHCO] +4 (1)
(In the formula (1), [CH ₂ ] and [NHCO] represent the number of methylene groups and the number of amide groups in the (A) aliphatic polyamide, respectively.)

  The content of the unit consisting of terephthalic acid in the (B) semi-aromatic polyamide is 60 mol% or more, preferably 75 mol% or more, more preferably 90 mol%, based on all dicarboxylic acid units. That's it. When the content of the terephthalic acid unit is less than 60 mol%, various physical properties such as heat resistance and easy tearability of the resulting film are not preferable.

  The dicarboxylic acid unit of the (B) semi-aromatic polyamide is a dicarboxylic acid unit other than the terephthalic acid unit as long as the excellent properties of the easily tearable biaxially stretched polyamide film of the present invention are not impaired. May be included. Examples of the other dicarboxylic acid units include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 2,2- Aliphatic dicarboxylic acids such as diethyl succinic acid, azelaic acid, sebacic acid, suberic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, and fats such as 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid Cyclic dicarboxylic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydi Acetic acid, diphenic acid, dibenzoic acid, 4,4'-oxydibenzoic acid, diphenylmeth -4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, units derived from aromatic dicarboxylic acid such as 4,4'-biphenyldicarboxylic acid, etc. Species or two or more can be used. Among the above units, units derived from aromatic dicarboxylic acids are preferred. The content of these other dicarboxylic acid units is 40 mol% or less, preferably 25 mol% or less, and preferably 10 mol% or less, based on all dicarboxylic acid units in the (B) semi-aromatic polyamide. It is more preferable that Furthermore, polycarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid can be used within a range where melt molding is possible.

Further, (B1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine unit in (B) semi-aromatic polyamide, and (b3) other than (b1) and (b2) ) The content of the aliphatic diamine unit is 60 mol% or more, preferably 75 mol% or more, more preferably 90 mol% or more based on the total diamine units. The content of (b1) 1,9-nonanediamine unit and / or (b2) 2-methyl-1,8-octanediamine unit and (b3) aliphatic diamine unit other than (b1) and (b2) is 60 mol. If it is less than%, various physical properties such as heat resistance and transparency of the resulting film are not preferred.
Further, the ratio of (b1) 1,9-nonanediamine and (b2) 2-methyl-1,8-octanediamine unit is (b1) :( b2) = from the viewpoint of the balance between moldability and impact resistance. It is preferably in the range of 30:70 to 99: 1 (mol%), more preferably in the range of 40:60 to 95: 5 (mol%), and 40:60 to 90:10 (mol). %) Is more preferable. By adjusting the composition ratio, it is possible to appropriately adjust the melting point of the (B) semi-aromatic polyamide.

(B3) Aliphatic diamine units other than (b1) and (b2) in the semi-aromatic polyamide (B) are appropriately selected from the conditions of the number of carbons calculated according to the type of (A) aliphatic polyamide. (A) Aliphatic diamine units other than (b1) 1,9-nonanediamine and (b2) 2-methyl-1,8-octanediamine units described in the explanation of aliphatic polyamide Can do.
The (b3) aliphatic diamine unit other than (b1) and (b2) preferably has carbon number n that satisfies the condition of the following formula (1), preferably the condition of the following formula (1 ′).
[CH ₂ ] / [NHCO] -2 ≦ n ≦ [CH ₂ ] / [NHCO] +4 (1)
[CH ₂ ] / [NHCO] ≦ n ≦ [CH ₂ ] / [NHCO] +2 (1 ′)
(In the formula (1) and the formula (1 ′), [CH ₂ ] and [NHCO] represent the number of methylene groups and the number of amide groups in the (A) aliphatic polyamide, respectively.

As described above, the aliphatic polyamide (A) in the raw material polyamide composition used in the present invention is at least one selected from the group consisting of polycaproamide (polyamide 6) and polyhexamethylene adipamide (polyamide 66). It is preferably a seed homopolymer or copolymer. Therefore, for example, when (A) the aliphatic polyamide is polycaproamide (polyamide 6) and polyhexamethylene adipamide (polyamide 66), [CH ₂ ] / [NHCO] = 5, and (B) semi-aromatic As (b3) aliphatic diamine units other than (b1) and (b2) in the aliphatic polyamide, an aliphatic diamine unit having 3 ≦ n ≦ 9, preferably 5 ≦ n ≦ 7 is selected. , 5-pentanediamine unit, 1,6-hexanediamine unit, 1,7-peptanediamine unit and the like. More preferred are 1,6-hexanediamine units. When (A) the aliphatic polyamide is a caproamide / hexamethylene adipamide copolymer (polyamide 6/66 copolymer), the [CH ₂ ] / [ NHCO] = 5, and similarly, (b3) an aliphatic diamine unit other than (b1) and (b2), an aliphatic diamine having 3 ≦ n ≦ 9, preferably 5 ≦ n ≦ 7. The unit is selected, and examples thereof include 1,5-pentanediamine unit, 1,6-hexanediamine unit, 1,7-peptanediamine unit and the like. More preferred are 1,6-hexanediamine units. When the aliphatic polyamide is polyhexamethylene dodecamide (polyamide 612), [CH ₂ ] / [NHCO] = 8, and (B) other than (b1) and (b2) in the semi-aromatic polyamide ( b3) As an aliphatic diamine unit, an aliphatic diamine unit having 6 ≦ n ≦ 12, preferably 8 ≦ n ≦ 10 (provided that (b1) 1,9-nonanediamine, (b2) 2-methyl- 1,8-octanediamine units are selected, preferably 1,8-octanediamine units, 2,2,4 / 2,4,4-trimethylhexamethylenediamine units, 1,10-decanediamine units Etc. In addition, the type of (b3) aliphatic diamine unit other than (b1) and (b2) is appropriately selected so as to satisfy the melting point condition described later in the raw material polyamide composition.

  (A) Aliphatic polyamide in the raw material polyamide composition used in the present invention is polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), caproamide / hexamethylene adipamide copolymer ( Polyamide 6/66 copolymer), and (B) semi-aromatic polyamide is nonamethylene terephthalamide / hexamethylene terephthalamide copolymer (polyamide 9T / 6T copolymer), nonamethylene terephthalate. A phthalamide / hexamethylene terephthalamide / hexamethylene adipamide copolymer (polyamide 9T / 6T / 66 copolymer) is preferred.

  Furthermore, in the raw material polyamide composition used in the present invention, (A) the melting point Tm (A) of the aliphatic polyamide and (B) the melting point Tm (B) of the semi-aromatic polyamide are | Tm (B)- It is necessary to satisfy Tm (A) | <50 ° C. Furthermore, it is preferable that | Tm (B) −Tm (A) | <40 ° C. When | Tm (B) −Tm (A) | ≧ 50 ° C., the film-forming stability is poor, and the transparency of the resulting film may be inferior.

  In this invention, melting | fusing point means the temperature of the peak of the heat of fusion curve measured using the differential scanning calorimeter normally used. Specifically, using a DSC-II manufactured by PERKIN-ELMER Co., Ltd., the sample was heated to a temperature above the expected melting point, and then the sample was cooled at a rate of 10 ° C. per minute, 30 The melting point is defined as the temperature of the peak of the heat of fusion curve measured by cooling to 0 ° C., leaving it for about 1 minute, and then raising the temperature at a rate of 10 ° C. per minute.

  In the diamine unit in the (B) semi-aromatic polyamide used in the present invention, (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine unit, (b1), It is preferable that the ratio with (b3) aliphatic diamine units other than (b2) is ((b1 + b2)) :( b3) = 30: 70 to 90:10 (mol%). When (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine unit is less than 30 mol%, the transparency of the film is excellent, but (A) a phase with an aliphatic polyamide In some cases, the solubility becomes too good, and good easy tearability is not exhibited. Moreover, when it exceeds 90 mol%, since it is inadequate in compatibility with (A) aliphatic polyamide, the transparency of the film may be inferior. The melting point of (B) semi-aromatic polyamide in the present invention is (b1) 1,9-nonanediamine unit and / or (b2) 2-methyl-1,8-octanediamine unit, and (b1), (b2 It is possible to satisfy the melting point condition defined in the present invention by adjusting the content ratio of (b3) aliphatic diamine units other than (b3), and (B1) in (B) semi-aromatic polyamide. The content ratio of 1,9-nonanediamine unit and / or (b2) 2-methyl-1,8-octanediamine unit and (b3) aliphatic diamine unit other than (b1) and (b2) is: In consideration of the compatibility with the group polyamide, it is determined to achieve both transparency and easy tearability of the resulting film.

  The diamine unit of the (B) semi-aromatic polyamide includes other diamine units other than the diamine unit as long as the excellent properties of the easily tearable biaxially stretched polyamide film of the present invention are not impaired. You may go out. Examples of the other diamine units include cycloaliphatic diamine, methylcyclohexanediamine, isophoronediamine and other alicyclic diamines, p-phenylenediamine, m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, 4,4 ′. -Units derived from aromatic diamines such as diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether can be mentioned, and one or more of these are used. be able to. The content of these other diamine units is 40 mol% or less, preferably 25 mol% or less, and preferably 10 mol% or less, based on all diamine acid units in (B) semi-aromatic polyamide. More preferably.

  The production apparatus used in the production of (A) aliphatic polyamide and (B) semi-aromatic polyamide used in the present invention includes a batch-type reaction kettle, a single-tank or multi-tank continuous reaction apparatus, and a tubular continuous A known polyamide production apparatus such as a reaction apparatus, a kneading reaction extruder such as a uniaxial kneading extruder or a biaxial kneading extruder can be used. As a polymerization method, a known method such as melt polymerization, solution polymerization, or solid phase polymerization can be used, and polymerization can be performed by repeating normal pressure, reduced pressure, and pressure operations. These polymerization methods can be used alone or in appropriate combination.

  The (A) aliphatic polyamide has a relative viscosity measured in accordance with JIS K-6920, preferably in the range of 2.0 to 5.0, more preferably 2.0 to 4.5. Within range. The relative viscosity of the (B) semi-aromatic polyamide is preferably in the range of 1.5 to 4.0, more preferably in the range of 1.8 to 3.5. When the relative viscosity is smaller than the above value, the mechanical properties of the obtained film may be lowered. On the other hand, if the value is larger than the above value, the viscosity at the time of melting increases, and it may be difficult to form a film.

  In addition, there is no special restriction | limiting in the kind of the terminal group of (A) aliphatic polyamide and (B) semi-aromatic polyamide, its density | concentration, and molecular weight distribution. One or more of monoamines, diamines, monocarboxylic acids, and dicarboxylic acids can be added in combination as appropriate for molecular weight adjustment and melt stabilization during molding. For example, alicyclic such as aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, cyclohexylamine, dicyclohexylamine Aromatic monoamines such as monoamine, aniline, toluidine, diphenylamine, and naphthylamine, aliphatic diamines such as 1,6-hexanediamine, 1,10-decanediamine, and 1,12-dodecanediamine, cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine Aromatic diamine such as alicyclic diamine, p-phenylenediamine, m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, and acetic acid Aliphatic monocarboxylic acids such as propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid, and cycloaliphatic carboxylic acid Aromatic monocarboxylic acids such as monocarboxylic acid, benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, phenylacetic acid, adipic acid, trimethyladipic acid, pimelic acid, azelaic acid, Aliphatic dicarboxylic acids such as sebacic acid, suberic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, 2,6 -Naphthalenedicarboxylic acid, 2,7-naphtha Njikarubon acid, and aromatic dicarboxylic acids such as 1,4-naphthalene dicarboxylic acid.

The amount of these molecular weight regulators to be used varies depending on the reactivity of the molecular weight regulator and the polymerization conditions, but is appropriately determined so that the relative viscosity of the finally obtained polyamide falls within the above range.
The specific amount used varies depending on the reactivity, boiling point, reaction apparatus, reaction conditions, etc. of the end-capping agent to be used, but is usually in the range of 0.1 to 10 mol% with respect to the total number of moles of raw material monomers. Used in.
In particular, the (B) semi-aromatic polyamide preferably has its molecular chain end sealed with an end-capping agent (monocarboxylic acid and / or monoamine) from the viewpoint of controlling the degree of polymerization. It is preferable that 10% or more is sealed, more preferably 40% or more of the end groups are sealed, and still more preferably 60% or more of the end groups are sealed. From the viewpoint of little discoloration of the resulting polymer, it is preferable that the end of the molecular chain is blocked with a monocarboxylic acid.

  The easily tearable biaxially stretched polyamide film of the present invention comprises a raw material polyamide composition containing (A) an aliphatic polyamide and (B) a semi-aromatic polyamide, and the weight ratio thereof is 65:35 to 95: 5. The ratio is preferably 70:30 to 90:10. When the ratio of (B) semi-aromatic polyamide is less than 5% with respect to the total weight of (A) aliphatic polyamide and (B) semi-aromatic polyamide, easy tearability when tearing in the longitudinal direction of the film When the ratio of (B) semi-aromatic polyamide exceeds 35% with respect to the total weight of (A) aliphatic polyamide and (B) semi-aromatic polyamide, the bending fatigue resistance of the film, The transparency is lowered, which is not preferable.

  In order to obtain the raw material polyamide composition in the present invention, (A) aliphatic polyamide and (B) semi-aromatic polyamide may be weighed, mixed and mixed in predetermined amounts. There is no restriction | limiting in particular in the method of mix | blending and mixing, The various methods conventionally known are employable. For example, it can be produced by a method of dry blending the two, a method of melt kneading them together with other components blended as necessary. The melt kneading can be performed using a kneader such as a single screw extruder, a twin screw extruder, a kneader, or a Banbury mixer.

  In the raw material polyamide composition used in the present invention, a lubricant, an antioxidant, a heat stabilizer, a weather resistance imparting agent, an antistatic agent, a water repellent, An anti-blocking agent, a bending fatigue resistance improving material, other thermoplastic resins, and the like can be blended.

In the present invention, as described above, (A) aliphatic polyamide and (B) semi-aromatic polyamide are used, and (A) the melt viscosity ratio R of (B) semi-aromatic polyamide to aliphatic polyamide is 0.2. It is preferred to select a polyamide that will be ~ 2.5. More preferably, it is 0.3-1.5. If the melt viscosity ratio R is larger than the above range, the dispersed particles of (B) semi-aromatic polyamide in the aliphatic polyamide (A) become large, and the number of dispersed particles per unit area expresses easy tearability. May be insufficient. On the other hand, when the melt viscosity ratio R is smaller than the above range, the difference in viscosity between the polyamides is large, and not only the film cannot be formed well, but the transparency of the film may be inferior. The melt viscosity ratio mentioned here is a shear rate of 1000 sec based on a shear rate-melt viscosity curve of (A) aliphatic polyamide and (B) semi-aromatic polyamide measured at a melting point + 30 ° C. with a known capillometer. ^{The value} of the apparent melt viscosity at ^-1 o'clock can be read and calculated.

  Next, the manufacturing method of the easily tearable biaxially stretched polyamide film of this invention is demonstrated. The easily tearable biaxially stretched polyamide film in the present invention can be produced by a conventionally known general method using the above polyamide composition as a raw material. For example, a raw material polyamide composition is melt-kneaded with an extruder, extruded into a flat film shape with a T-die or a coat hanger die, cast on a casting roll surface, cooled, and a film is produced by casting. A tubular method for producing a film by air-cooling or water-cooling a tubular product melt-extruded into a shape. By these methods, a substantially non-oriented unstretched film is obtained.

  When obtaining an unstretched film, pay attention to the maximum shear rate of the screw metering section in the extruder, the residence time of the resin, the resin temperature, and the draft ratio of the melt extrusion process (die lip clearance / film thickness after take-up). It becomes possible to obtain a film excellent in easy tearability. These are important factors that determine the dispersion shape of the (B) semi-aromatic polyamide particles in the (A) aliphatic polyamide, and optimal conditions are appropriately selected according to the specification conditions of the apparatus.

  The unstretched film obtained can be stretched by a conventionally known industrial method. For example, a film produced by the casting method is a tenter simultaneous biaxial stretching method in which an unstretched sheet is stretched simultaneously in the longitudinal and transverse directions with a tenter-type simultaneous biaxial stretching machine, and an unstretched sheet melt-extruded from a T-die is longitudinally stretched with a roll-type stretching machine. A tenter sequential biaxial stretching method in which the film is stretched in the direction and then stretched in the transverse direction by a tenter type stretching machine. Moreover, the tubular extending | stretching method which extends | stretches the tubular sheet | seat shape | molded from the cyclic | annular die | dye vertically and horizontally simultaneously with the pressure of gas is mentioned. The stretching step may be carried out continuously following the production of the polyamide film, or the polyamide film may be wound once and then stretched as a separate step. Alternatively, the unstretched sheet may be immersed in warm water to adjust the moisture content of the sheet to 0.3 to 10% by weight. Due to moisture management of the unstretched film, there is an effect of preventing the occurrence of localized stretch spots when stretching.

  The stretch ratio of the stretched film varies depending on the intended use, but is usually 1.5 to 4.0 times in both the longitudinal direction and the transverse direction in both the tenter-type biaxial stretching method and the tubular method. More preferably, the vertical and horizontal directions are 2.5 to 4.0 times. The stretching temperature is preferably 30 to 210 ° C, more preferably 50 to 200 ° C.

It is desirable that the film stretched by the above method is subsequently heat treated. Dimensional stability at room temperature can be imparted by heat treatment. The heat treatment temperature in this case is preferably selected in a range where the lower limit is 110 ° C. and the upper limit is a temperature 5 ° C. lower than the melting point of the raw material polyamide composition. A stretched film having the above can be obtained. The easily tearable biaxially stretched polyamide film of the present invention preferably has poor heat shrinkability or substantially does not have it. Therefore, in the heat treatment conditions performed after stretching, the treatment temperature is preferably 150 ° C. or higher, more preferably 180 to 220 ° C., and the relaxation rate is preferably within 20% in the width direction, and more preferably 3 to 10 %.
The stretched film that has been sufficiently heat-set by the heat treatment operation can be cooled and wound up according to a conventional method.

  Furthermore, the easily tearable biaxially stretched polyamide film of the present invention can be subjected to surface treatment such as corona discharge treatment, plasma treatment, flame treatment, acid treatment, etc., in order to improve the printability, laminating properties, and adhesive application properties. . Moreover, after performing such a process as needed, it can be used for each intended use through secondary processing steps such as printing, laminating, adhesive application, and heat sealing.

  The easily tearable biaxially stretched polyamide film according to the present invention has excellent tearability and transparency, and has a high utility value by itself. However, by laminating other thermoplastic resins, more properties can be added. It is possible. Specifically, a layer made of a thermoplastic resin can be laminated on at least one surface of the easily tearable biaxially stretched polyamide film of the present invention to be used as a laminated film.

  In producing the laminated film, another substrate is laminated on one side or both sides of the layer made of the raw material polyamide composition. Examples of the laminating method include a co-extrusion method, an extrusion laminating method, and a dry laminating method. It is done. The coextrusion method is a method of coextruding the raw material polyamide composition and another thermoplastic resin, and examples thereof include coextrusion sheet molding, coextrusion casting film molding, and coextrusion inflation film molding. In the case of the extrusion laminating method, each roll is applied while melt-extrusion of the thermoplastic resin or the like is applied between the anchor coat agent on the easily tearable biaxially stretched polyamide film of the present invention and the thermoplastic resin, respectively, and drying. A laminate film can be obtained by cooling between the layers and press-bonding them under pressure. In the case of the dry laminating method, a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound is applied to the easily tearable biaxially stretched polyamide film of the present invention, and after drying, a thermoplastic resin or the like is used. A laminate film is obtained by laminating with a substrate. The film after lamination can be increased in adhesive strength by aging. When laminating, it is preferable to use one or both sides of the film after corona treatment.

  Other thermoplastic resins to be laminated include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra high molecular weight polyethylene (UHMWPE), Polypropylene (PP), ethylene / propylene copolymer (EPR), ethylene / butene copolymer (EBR), ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl acetate copolymer saponified product (EVOH), ethylene / Acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EMAA), ethylene / methyl acrylate copolymer (EMA), ethylene / methyl methacrylate copolymer (EMMA), ethylene / ethyl acrylate Polyolefin resins such as copolymers (EEA), acrylic acid, Tacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, mesaconic acid, citraconic acid, glutaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endobicyclo- [2.2.1] -5 Carboxyl groups such as heptene-2,3-dicarboxylic acid and metal salts thereof (Na, Zn, K, Ca, Mg), maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo- [2.2.1] Contains functional groups such as acid anhydride groups such as -5-heptene-2,3-dicarboxylic acid anhydride, epoxy groups such as glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, and glycidyl citraconic acid. The above-mentioned polyolefin resin, polybutylene terephthalate (PBT), polyethylene modified with the above compound Polyester resins such as rephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), polyethylene naphthalate (PEN), liquid crystal polyester (LCP) Polyether resins such as polyacetal (POM) and polyphenylene oxide (PPO), polysulfone resins such as polysulfone (PSF) and polyethersulfone (PES), polyphenylene sulfide (PPS), polythioethersulfone (PTES) and other polysulfone resins Polyketone resins such as thioether resin, polyether ether ketone (PEEK), polyallyl ether ketone (PAEK), polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / Styrene copolymer (AS), methacrylonitrile / styrene copolymer, polynitrile resin such as acrylonitrile / budadiene / styrene copolymer (ABS), methacrylonitrile / styrene / butadiene copolymer (MBS), poly Polymethacrylate resins such as methyl methacrylate (PMMA) and polyethyl methacrylate (PEMA), polyvinyl ester resins such as polyvinyl acetate (PVAc), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / Polyvinyl chloride resins such as vinylidene chloride copolymers, vinylidene chloride / methyl acrylate copolymers, cellulose resins such as cellulose acetate and cellulose butyrate, polycarbonate resins such as polycarbonate (PC), thermoplastic polyimide (PI) ,polyamide Polyimide resin such as imide (PAI), polyetherimide, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene / Chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene / hexafluoropropylene copolymer (TFE / HFP, FEP), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (TFE / HFP / VDF) , THV), fluororesins such as tetrafluoroethylene / fluoro (alkyl vinyl ether) copolymer (PFA), thermoplastic polyurethane resins, polyurethane elastomers, polyester elastomers, polyamide elastomers It can be mentioned over and the like. Other polyamide resins include polyhexamethylene terephthalamide (polyamide 6T), polyhexamethylene isophthalamide (polyamide 6I), polytrimethylhexamethylene terephthalamide (polyamide TMHT), polymetaxylylene adipamide ( Polyamide MXD6), polybis (4-aminocyclohexyl) methane dodecamide (polyamide PACM12), polybis (3-methyl-4-aminocyclohexyl) methane dodecamide (polyamide dimethyl PACM12), polyisophorone adipamide (polyamide IPD6), poly Isophorone terephthalamide (polyamide IPDT), polynonamethylene hexahydroterephthalamide (polyamide 9T (H)), polynonamethylene isophthalamide (polyamide 9I), polynonameti Nonaphthalamide (polyamide 9N), polydecamethylene terephthalamide (polyamide 10T), polydecamethylene isophthalamide (polyamide 10I), polydecamethylene hexahydroterephthalamide (polyamide 10T (H)), polydecamethylene naphthalamide ( Polyamide 10N), polyundecamethylene terephthalamide (polyamide 11T), polyundecamethylene isophthalamide (polyamide 11I), polyundecamethylene hexahydroterephthalamide (polyamide 11T (H)), polyundecamethylene naphtha Lamid (polyamide 11N), polydodecamethylene terephthalamide (polyamide 12T), polydodecamethylene isophthalamide (polyamide 12I), polydodecamethylene hexahydroterephthalamide (polyamide 1) T (H)), poly dodecamethylene naphthalate La bromide (polyamide 12N) and can be exemplified those polyamide raw material monomers and a copolymer using several kinds of. Furthermore, (A) aliphatic polyamide and (B) semi-aromatic polyamide can be laminated, and from the viewpoint of balance of film strength and gas barrier properties, (A) aliphatic polyamide and polymetaxylylene adipamide It is preferable to laminate (polyamide MXD6).

  In the easily tearable biaxially stretched polyamide film of the present invention, it is desirable to provide a sealant layer from the viewpoint of imparting heat sealability. The material used for the sealant layer may be any resin that can be heat-sealed, and generally includes polyolefin resins, polyester resins, and the like, and it is preferable to use polyolefin resins. Specifically, polypropylene (PP), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene / vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer (EAA), ethylene / Methacrylic acid copolymer (EMAA), ethylene / methyl acrylate copolymer (EMA), ethylene / methyl methacrylate copolymer (EMMA), ethylene / ethyl acrylate copolymer (EEA), ionomer resin, amorphous Polyester (A-PET) etc. are mentioned as a preferable thing.

  It is also possible to laminate any substrate other than thermoplastic resin, such as paper, metal-based material, non-stretched, uniaxially or biaxially stretched plastic film or sheet, woven fabric, non-woven fabric, metal cotton, wood, etc. is there. Examples of the metal-based material include aluminum, iron, copper, nickel, gold, silver, titanium, molybdenum, magnesium, manganese, lead, tin, chromium, beryllium, tungsten, cobalt, and other metals and metal compounds, and two or more of these. Examples include alloy steels such as stainless steel, aluminum alloys, copper alloys such as brass and bronze, and alloys such as nickel alloys.

  Furthermore, the laminated film including the easily tearable biaxially stretched polyamide film of the present invention is used as a constituent material of any base material such as a thermoplastic resin, paper, or metal foil as described above. The number of layers is not particularly limited as long as the easily tearable biaxially stretched polyamide film is used in at least one layer and the laminated film has easy tearability. In order not to destroy the excellent tearability of the easy-tearable biaxially stretched polyamide film of the present invention, the base material to be laminated is carefully considered in the direction in which the film is easy to tear, and the type and the order of lamination are determined. It is good to decide.

  The thickness of the easily tearable biaxially stretched polyamide film of the present invention is not particularly limited as long as it is appropriately determined depending on the use. However, the thickness of the film improves the strength of the polyamide film, but the transparency and easy tear Therefore, in the case of a single layer film, the thickness is preferably 5 to 100 μm, more preferably 10 to 80 μm, and further preferably 10 to 60 μm. In the case of a laminated film, the thickness of the raw material polyamide composition layer is preferably 2 to 100 μm, more preferably 5 to 80 μm, and still more preferably 10 to 60 μm.

  The easily tearable biaxially stretched polyamide film of the present invention has excellent toughness, bending fatigue resistance, dimensional stability, and excellent tearability in the longitudinal direction of the film, and is therefore suitable as a packaging bag body. . Laminate films are laminated to each other by thermally welding the end portions of the thermoplastic resin films so that the longitudinal direction of the film of the present invention is the tear direction, and an easily openable packaging bag body is obtained. . There is no restriction | limiting in the method at the time of manufacturing a bag body, It is set as a bag body by methods, such as a conventional palm joining, a three-sided seal, and envelope pasting. It is preferable to make a notch in the tearing part of the seal part of the bag so that it can be easily torn. The form of the notch is not particularly limited as long as it is a generally adopted form. Thus, since this packaging bag body has excellent easy tearability, it is useful as a packaging bag body for foods such as soups, jams, retort pouches, medical products, medicines, daily necessities, toiletries and the like.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited thereto.
In addition, the analysis in an Example and a comparative example, the measuring method of a film physical property, and the used material are shown below.

[Relative viscosity]
According to JIS K-6920, the measurement was performed in 96% sulfuric acid under the conditions of a polyamide concentration of 1% and a temperature of 25 ° C.
[Melting point]
Using a DSC-II manufactured by PERKIN-ELMER, the sample was heated to a temperature above the expected melting point, and then the sample was cooled at a rate of 10 ° C. per minute, cooled to 30 ° C. The temperature of the peak of the heat of fusion curve measured by standing for about 1 minute and then raising the temperature at a rate of 10 ° C. per minute was read.

[Film physical property evaluation]
[transparency]
Haze, which is a measure of transparency, was measured using a direct reading haze computer (HGM-2DP) manufactured by Suga Test Instruments Co., Ltd. according to ASTM D-1003. When the haze value was 4.0% or less, it was judged that the transparency was excellent.

[Easily tearable]
Cut one end in the TD direction of the film at intervals of 20 mm (W0), and measure the deviation width (W1) of the other end without a cut when tearing 200 mm in the MD direction of the film along these. The deviation rate D (%) at the time of tearing was calculated from the equation. When the deviation rate was 15% or less, it was judged that the easy tearability was excellent.
D = (W1 / W0) × 100

[Bending fatigue resistance]
A film cut to a size of 8 inches × 11 inches was conditioned for 24 hours or more under the conditions of a temperature of 23 ° C. and a relative humidity of 65%, and a gelbo flex tester manufactured by Rigaku Industry Co., Ltd. was used. The number of pinholes generated after 2000 bending tests at a temperature of 23 ° C. was measured by a method based on MIL-B-131C. When the number of pinholes was 10 or less, it was judged that the bending fatigue resistance was excellent.

[Materials Used in Examples and Comparative Examples]
(A) Aliphatic polyamide (A-1) Polyamide 6 (UBE Nylon 1022B relative viscosity 3.35 melting point 220 ° C., manufactured by Ube Industries, Ltd.)
(A-2) Polyamide 66 (UBE Nylon 2026B relative viscosity 3.36 melting point 255 ° C., manufactured by Ube Industries, Ltd.)
(A-3) Polyamide 12 (UBESTA 3020B relative viscosity 1.80 melting point 178 ° C., manufactured by Ube Industries, Ltd.)

(B) Production of semi-aromatic polyamide (B-1) semi-aromatic polyamide 32927 g (198.2 mol) of terephthalic acid, 11080 g (70 mol) of 1,9-nonanediamine (b2) 2-methyl-1 , 8-octanediamine 11080 g (70 mol), (b3) 1,6-hexanediamine 6972 g (60 mol), benzoic acid 586.2 g (4.8 mol), sodium hypophosphite monohydrate 63 g (raw material) 0.1 wt%) and 40 L of distilled water were placed in an autoclave and purged with nitrogen.
The mixture was stirred at 100 ° C. for 30 minutes, and the internal temperature was raised to 190 ° C. over 2 hours. At this time, the autoclave was pressurized to 2.2 MPa. The reaction was continued as it was for 1 hour, then the temperature was raised to 200 ° C., and then the temperature was maintained at 200 ° C. for 2 hours, and the reaction was carried out while gradually removing water vapor and keeping the pressure at 2.2 MPa. Next, the pressure was reduced to 1 MPa over 30 minutes, and the reaction was further continued for 1 hour to obtain a prepolymer. This was dried at 100 ° C. under reduced pressure for 12 hours and pulverized to a size of 2 mm or less. This was subjected to solid phase polymerization at 210 ° C. and 0.013 kPa for 8 hours to obtain a semi-aromatic polyamide having a melting point of 245 ° C. and a relative viscosity of 2.15 (hereinafter, this semi-aromatic polyamide (B- 1)).

(B-2) Production of semi-aromatic polyamide (B-1) In production of semi-aromatic polyamide, (b1) 1,1080 g (70 mol) of 1,9-nonanediamine, (b2) 2-methyl-1,8-octane Diamine 11080 g (70 mol), (b3) 1,6-hexanediamine 6972 g (60 mol) (b1) 1,9-nonanediamine 9497 g (60 mol), (b2) 2-methyl-1,8-octanediamine 9497 g (B-1) Except for changing to 9297 g (80 mol) of (b3) 1,6-hexanediamine, (B-1) The melting point was 226 ° C. and the relative viscosity was the same as the production of the semi-aromatic polyamide. 2.20 semi-aromatic polyamide was obtained (hereinafter, this semi-aromatic polyamide is referred to as (B-2)).

(B-3) Production of semi-aromatic polyamide (B-1) In the production of semi-aromatic polyamide, except that the solid-state polymerization time was changed from 8 hours to 10 hours, A semi-aromatic polyamide having a melting point of 245 ° C. and a relative viscosity of 2.35 was obtained in the same manner as in the production (hereinafter, this semi-aromatic polyamide is referred to as (B-3)).

(B-4) Production of semi-aromatic polyamide (B-1) In production of semi-aromatic polyamide, (b1) 1,1080 g (70 mol) of 1,9-nonanediamine, (b2) 2-methyl-1,8-octane Diamine 11080 g (70 mol), (b3) 1,6-hexanediamine 6972 g (60 mol), (b1) 1,9-nonanediamine 26909 g (170 mol), (b2) 2-methyl-1,8-octanediamine A semi-aromatic polyamide having a melting point of 306 ° C. and a relative viscosity of 2.20 was obtained in the same manner as in the production of (B-1) semi-aromatic polyamide except that the amount was changed to 4748.7 g (30 mol) ( Hereinafter, this semi-aromatic polyamide is referred to as (B-4)).

(C) Polyamide MXD6 (Mitsubishi Gas Chemical Co., Ltd., MX-6011)

Example 1
With respect to 100 parts by weight of the polyamide composition blended with (A) aliphatic polyamide (A-1) and (B) semi-aromatic polyamide (B-1) in the ratio shown in Table 1, ethylene bisstearylamide (EBS) ) In a 40 mmφ extruder equipped with a circular die, melted at an extrusion temperature of 270 ° C., and cooled with 20 ° C. water. The tubular polyamide unstretched film which was taken up was substantially amorphous and not oriented. Subsequently, stretching was performed at a stretching temperature of 180 ° C. and a stretching ratio (both longitudinal and lateral) of 3.0 times by a tubular stretching method in which a longitudinal and lateral stretching was simultaneously performed in an inflation type with a gas pressure. Then, the end of the tubular film was cut open, the flat film was introduced into the tenter, and heat-fixed at 210 ° C. while performing relaxation treatment in the width direction. Both ends of the film were released from the clip, and the ears were trimmed and wound to obtain a biaxially stretched polyamide film having a thickness of 15 μm. The melting point Tm (A) of the (A) aliphatic polyamide (A-1) constituting the polyamide composition is 220 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-1) is 245 ° C. Yes, | Tm (B) −Tm (A) | = 25 <50 ° C. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Examples 2-3
Example 1 is the same as Example 1 except that the blending ratio of (A) aliphatic polyamide (A-1) and (B) semi-aromatic polyamide (B-1) is changed to the ratio shown in Table 1. A biaxially stretched polyamide film was obtained by this method. The melting point Tm (A) of the (A) aliphatic polyamide (A-1) constituting the polyamide composition is 220 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-1) is 245 ° C. Yes, | Tm (B) −Tm (A) | = 25 <50 ° C. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Example 4
In Example 1, the same method as in Example 1 except that (A) the aliphatic polyamide (A-1) was changed to (A-2), the stretching temperature was changed to 200 ° C, and the heat setting temperature was changed to 230 ° C. A biaxially stretched polyamide film was obtained. The melting point Tm (A) of the (A) aliphatic polyamide (A-2) constituting the polyamide composition is 255 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-1) is 245 ° C. Yes, | Tm (B) −Tm (A) | = 10 <50 ° C. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Example 5
In Example 1, the biaxially stretched polyamide film was prepared in the same manner as in Example 1 except that (B) the semi-aromatic polyamide (B-1) was changed to (B-2) and the extrusion temperature was changed to 250 ° C. Got. The melting point Tm (A) of the (A) aliphatic polyamide (A-1) constituting the polyamide composition is 220 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-2) is 226 ° C. Yes, | Tm (B) −Tm (A) | = 6 <50 ° C. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Example 6
A biaxially stretched polyamide film was obtained in the same manner as in Example 1, except that (B) the semi-aromatic polyamide (B-1) was changed to (B-3) in Example 1. The melting point Tm (A) of the (A) aliphatic polyamide (A-1) constituting the polyamide composition is 220 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-1) is 245 ° C. Yes, | Tm (B) −Tm (A) | = 25 <50 ° C. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Example 7
After corona treatment on both sides of the biaxially stretched polyamide film (ONY) obtained in Example 1, an isocyanate anchor coating agent (AD-900 / AD-RT-10 manufactured by Toyo Morton Co., Ltd.) was applied to the corona treatment surface. After applying 0.4 g / m ² as a solid content and evaporating the solvent, an unstretched polypropylene film (CPP) having a thickness of 60 μm and a polyethylene terephthalate film (PET) having a thickness of 12 μm were laminated, and 40 ° C., 48 hours. By aging, a laminate film of PET / ONY / CPP was obtained. Using this film, a four-side sealed bag consisting of 200 mm each in the longitudinal direction and the width direction was produced, and easy tearability was evaluated by the above method. The deviation rate was 12%, indicating good tearability.

Comparative Examples 1-3
Example 1 is the same as Example 1 except that the blending ratio of (A) aliphatic polyamide (A-1) and (B) semi-aromatic polyamide (B-1) is changed to the ratio shown in Table 1. A biaxially stretched polyamide film was obtained by this method. The melting point Tm (A) of the (A) aliphatic polyamide (A-1) constituting the polyamide composition is 220 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-2) is 245 ° C. Yes, | Tm (B) −Tm (A) | = 25 <50 ° C. However, the blending ratio of (A) aliphatic polyamide and (B) semi-aromatic polyamide specified in the present invention is not satisfied. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Comparative Example 4
A biaxially stretched polyamide film was prepared in the same manner as in Example 1, except that (B) the semi-aromatic polyamide (B-1) was changed to (B-4) and the extrusion temperature was changed to 330 ° C. However, stable film formation was not possible. The melting point Tm (A) of the (A) aliphatic polyamide (A-1) constituting the polyamide composition is 220 ° C., and the melting point Tm (B) of the semi-aromatic polyamide (B-4) is 306 ° C. Yes, | Tm (B) −Tm (A) | = 86> 50 ° C., which does not satisfy the provisions of the present invention.

Comparative Example 5
In Example 1, biaxially stretched polyamide was prepared in the same manner as in Example 1 except that (B) semi-aromatic polyamide (B-1) was changed to (C) polyamide MXD6 and the blending ratio shown in Table 1 was changed. A film was obtained. The (C) polyamide MXD6 used is a polyamide other than the (B) semi-aromatic polyamide defined in the present invention. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Comparative Example 6
In Example 1, (B) semi-aromatic polyamide (B-1) was changed to (A) aliphatic polyamide (A-3), the extrusion temperature was changed to 260 ° C., and the mixing ratio shown in Table 1 was changed. Except for this, a biaxially stretched polyamide film was obtained in the same manner as in Example 1. The (A) aliphatic polyamide (A-3) used is a polyamide other than the (B) semi-aromatic polyamide defined in the present invention. The physical property measurement results of the obtained biaxially stretched polyamide film are shown in Table 1.

Comparative Example 7
In Example 7, the laminate film was obtained in the same manner as in Example 7 except that the biaxially stretched polyamide film obtained in Example 1 was changed to the biaxially stretched polyamide film obtained in Comparative Example 1. It produced and evaluated easy tearability by said method. The deviation rate was 105% and did not show good easy tearability.

Claims (5)

(A) 65-95% by weight of aliphatic polyamide and (B) total diamine units, (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine units, and (B3) other than (b1) and (b2) satisfying the condition of the formula (1) (b3) a diamine unit containing 60 mol% or more of an aliphatic diamine unit, and a terephthalic acid unit relative to all dicarboxylic acid units Is a biaxially stretched polyamide film comprising a polyamide composition comprising 35 to 5% by weight of a semi-aromatic polyamide comprising 60 mol% or more of a dicarboxylic acid unit, the (A) aliphatic polyamide and the (B) half An easily tearable biaxially stretched polyamide film, wherein the aromatic polyamide satisfies the condition of the following formula (2).
[CH ₂ ] / [NHCO] -2 ≦ n ≦ [CH ₂ ] / [NHCO] +4 (1)
(In the formula (1), [CH ₂ ] and [NHCO] represent the number of methylene groups and the number of amide groups in the (A) aliphatic polyamide, respectively.)
| Tm (B) -Tm (A) | <50 ° C. (2)
(In Formula (2), Tm (A) and Tm (B) represent the melting points of (A) aliphatic polyamide and (B) semi-aromatic polyamide, respectively).   (A) The aliphatic polyamide is at least one homopolymer or copolymer selected from the group consisting of polycaprolactam (polyamide 6) and polyhexamethylene adipamide (polyamide 66). Item 2. The easily tearable biaxially stretched polyamide film according to Item 1.   (B) In the diamine unit of the semi-aromatic polyamide, (b1) 1,9-nonanediamine and / or (b2) 2-methyl-1,8-octanediamine unit and carbon number n satisfying the condition of formula (1) The ratio with (b3) aliphatic diamine units other than (b1) and (b2) is ((b1) + (b2)) :( b3) = 30: 70 to 90:10 (mol%) The easily tearable biaxially stretched polyamide film according to claim 1 or 2.   The laminated film which has the tear property which uses the biaxially stretched polyamide film in any one of Claims 1-3 for at least 1 layer.   An easy-open packaging bag body having easy tearability, wherein the laminated film according to claim 4 is used to make a bag so that the longitudinal direction of the biaxially stretched polyamide film is the tear direction.