JP2006150617A - Polyester film laminate and gas barrier easy-opening packaging bag using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film laminate having both of the easy openability and gas barrier properties of a packaging bag easy to tear for food, medicines, general merchandise and the like even if printing is applied. <P>SOLUTION: The polyester film laminate is constituted of a biaxially stretched polyester film, at least one kind of a film other than it, a vapor deposition layer and a printing layer. The biaxially stretched polyester film is manufactured using a raw material prepared by mixing polyethylene terephthalate (PET) and a polyester elastomer in a ratio of PET/polyester elastomer of 70/30-95/5 (mass ratio). The vapor deposition layer comprises at least one kind of a metal compound among aluminum oxide and silicon oxide and is laminated at least on one side of the biaxially stretched polyester film. The printing layer is laminated on the surface of the vapor deposition layer and the tear propagation resistance of the laminate is 1,500 mN or below. This polyester film laminate has gas barrier properties and tear straight advance properties. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyester film laminate having at least a longitudinal tear linearity of a film, a low tear resistance, and an excellent gas barrier property, and a gas barrier easy-open packaging bag using the same. is there.

  Many packaging bags using various plastic films are used for packaging foods, pharmaceuticals, and miscellaneous goods, and it consists of two or more layers laminated with a biaxially stretched plastic film and a heat-sealable non-oriented plastic. Packaging bags are used. In particular, in recent years, the number of cases in which a gas barrier film is used is greatly increased so that the best-before period, the best-before date, and the like can be extended. The biaxially stretched polyester film is excellent in strength, dimensional stability, and fragrance retention, but for food packaging applications that require long-term storage, a higher barrier property against oxygen and water vapor is required. As gas barrier materials for packaging applications, polyvinylidene chloride film, ethylene vinyl alcohol film, and film laminated with aluminum foil are used. The use of materials that generate incineration residues, such as, and materials that generate chlorine gas during incineration, such as polyvinylidene chloride, is restricted. In addition, the use of dioxins, which are subject to emission restrictions in incinerators, is a concern, and it is estimated that usage will be further reduced. There are also aluminum vapor deposition films, but there are problems such as invisible contents and inability to use the range. Therefore, a transparent vapor deposition film is used.

  In addition, the packaging bag is required to have two characteristics that seem to be contradictory to each other in strength and easy tearability when opened. Conventionally used easy-opening techniques include making V-notches and U-notches, tear tapes, perforations, and fine scratches on the film surface. However, with such conventional techniques, there are problems such as requiring more force than necessary even when torn, and troubles such as not being able to tear linearly, and soiling clothes and furniture. . Moreover, as an easily openable material excellent in tearing linearity when the film is torn, there is one obtained by laminating a uniaxially stretched polyolefin film as an intermediate layer. As such a configuration, for example, there is a three-layer laminated film of biaxially stretched polyester film / uniaxially stretched polyolefin film / unstretched polyolefin film, but there is a problem in terms of cost because an intermediate layer must be provided. Applications were limited.

The present applicant previously made a polybutylene terephthalate (modified PBT) containing 5 to 20% by weight of a polytetramethylene glycol (PTMG) unit having a molecular weight of 600 to 4000, and polyethylene terephthalate (PET), PET / modified PBT. By depositing a metal compound such as aluminum oxide or silicon oxide on at least one surface of a biaxially stretched polyester film produced using raw materials mixed at a ratio of 70/30 to 95/5 (weight ratio), The problem was solved (Patent Document 1).
However, when printing is performed on the vapor-deposited layer surface of this film and another film is laminated, the tear resistance may be increased particularly in the printed part, although there is a tearing straightness, and there is a demand for easier tearing. It was.

On the other hand, when a film on which an inorganic material is deposited is processed with another resin film or sheet to form a packaging material, there is a problem that conventional adhesives for laminating or anchor coating agents have low adhesive strength. In order to solve this problem, although the adhesiveness and tearability are improved by using a mixture of a polyurethane resin and a silane coupling agent and / or an adhesive mainly composed of a reaction product, The tearability and straight tearability were insufficient (Patent Document 2).
JP 2001-162752 A JP 2002-275448 A

  The present invention solves the above-mentioned problems and is easy to tear even when printing is performed, and a polyester film laminate that combines easy opening and gas barrier properties of packaging bags for foods, pharmaceuticals, miscellaneous goods, etc. A gas barrier easy-open packaging bag is to be provided.

As a result of intensive studies on methods for solving the above problems, the present inventors have solved the above problems by using the following films. That is, the gist of the present invention is as follows.
(1) A laminate comprising a biaxially stretched polyester film, at least one other type of film, a vapor deposition layer, and a printing layer, wherein the biaxially stretched polyester film comprises polyethylene terephthalate (PET) and a polyester elastomer. And PET / polyester elastomer = 70/30 to 95/5 (mass ratio). The vapor deposition layer is at least one metal compound of aluminum oxide and silicon oxide. The vapor barrier layer is laminated on at least one surface of the biaxially stretched polyester film, the printed layer is laminated on the vapor deposition layer surface, and the tear propagation resistance of the laminate is 1500 mN or less, and has a gas barrier property. A polyester film laminate having straight tearability.
(2) The polyester film laminate according to (1), wherein the polyester elastomer is polybutylene terephthalate (modified PBT) containing 5 to 20% by mass of a polytetramethylene glycol unit having a molecular weight of 600 to 4000.
(3) The polyester film laminate according to (1) or (2), wherein the printed layer is formed of an ink to which a silane coupling agent is added.
(4) A gas-barrier easy-open packaging bag formed by using the laminate according to any one of (1) to (3) above and making the bag so that the easy tear direction is the tear direction of the bag.

  Using the polyester film laminate of the present invention, by making a bag so that the tearing direction is the easy tearing direction of the film, an easy-open bag can be obtained even if printing is performed. It can be usefully used as a packaging bag.

  The PET in the present invention is obtained by a known production method, that is, an ester exchange reaction method from dimethyl terephthalate and ethylene glycol or a direct esterification method from terephthalic acid and ethylene glycol, followed by melt polymerization, Alternatively, it can be obtained by further solid phase polymerization, but other components can be copolymerized as long as the effects of the present invention are not impaired.

  Other copolymer components include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, maleic anhydride, maleic acid Acids, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, dicarboxylic acids such as cyclohexanedicarboxylic acid, 4-hydroxybenzoic acid, ε-caprolactone, oxycarboxylic acids such as lactic acid, 1,3-propanediol, 1,6- Examples thereof include glycols such as hexanediol and cyclohexanedimethanol, and polyfunctional compounds such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin, and pentaerythritol.

  The polyester elastomer in the present invention is composed of a crystalline hard segment and an amorphous soft segment. Examples of the crystalline hard segment include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Terephthalate (PBT) is preferred. On the other hand, examples of the amorphous soft segment include polytetramethylene glycol (PTMG), polyethylene glycol (PEG), and polybutylene glycol (PBG). Among these, PTMG is preferable. A polyester elastomer (modified PBT) in which the crystalline hard segment is PBT and the amorphous soft segment is PTMG is, for example, when a polymerization reaction of polybutylene terephthalate is performed by a conventional method using terephthalic acid and butylene glycol. It can be obtained by adding polytetramethylene glycol.

  In the present invention, when PTMG is used as the amorphous soft segment, the molecular weight is preferably 600 to 4000, more preferably 1000 to 3000, and more preferably 1000 to 2000. When the molecular weight is less than 600, the tear linearity may be deteriorated. When it exceeds 4000, the performance such as mechanical strength, dimensional stability, haze, and the like is deteriorated. May not develop.

  In this invention, 5-20 mass% is preferable, as for content of the PTMG unit which is a structural component of modified PBT, 10-20 mass% is more preferable, and 10-15 mass% is more preferable. When the PTMG content is less than 5% by mass, the obtained biaxially stretched polyester film does not exhibit the tear linearity, and when it exceeds 20% by mass, the resulting film has mechanical strength and dimensional stability. In addition, the performance such as haze is deteriorated, and it is difficult to obtain stable tear linearity of the film. In addition, when the content of PTMG exceeds 20% by mass, a phenomenon in which the film pulsates during extrusion (so-called ballast phenomenon) may occur, particularly when produced on a mass production scale. A problem occurs.

  In order to produce the biaxially stretched polyester film in the present invention, the mixing ratio of PET and polyester elastomer is PET / polyester elastomer = 70/30 to 95/5 (mass ratio), preferably 80/20 to 90/10. (Mass ratio), more preferably 85/15 to 90/10 (mass ratio). When the mixing ratio of the polyester elastomer is less than 5% by mass, the tear linearity cannot be obtained, and when it exceeds 30% by mass, the thickness variation of the film increases or the tear linearity of the obtained film decreases. In addition, mechanical strength, dimensional stability, haze, and other performances are reduced, causing problems in practical performance.

  As a method for producing a polyester elastomer in the present invention, when the polyester elastomer is a modified PBT, it can be obtained by polycondensation by adding PTMG in the polymerization process of PBT. However, as a simpler method, PBT and PTMG can be obtained. Can also be obtained by melt-kneading with an extruder.

  In addition, other polymers such as polyethylene naphthalate and polycyclohexylenedimethylene terephthalate can be mixed into the raw resin for the biaxially stretched polyester film in the present invention as long as the effects of the present invention are not impaired. In addition, ultraviolet absorbers, antioxidants, antistatic agents, surfactants, pigments, fluorescent brighteners, etc., inorganic particles such as silica, calcium carbonate, titanium oxide, etc., organic particles containing acrylic, styrene, etc. as constituent components May be appropriately contained as necessary.

  In order to produce the biaxially stretched polyester film in the present invention, for example, a mixture of modified PBT and PET is put into an extruder, heated and melted, and then extruded into a sheet form from a die orifice of a T die, and an unstretched sheet Manufacturing. Next, the sheet extruded from the die orifice of the T die is cooled by being closely attached to a cooling drum by an electrostatic application casting method or the like, at a temperature of 80 to 140 ° C., and 3.0 to 5. The film is stretched at a magnification of 0, and further heat treated at a temperature of 210 to 245 ° C. to obtain a biaxially stretched film.

  When the stretching temperature is less than 90 ° C, a homogeneous stretched film may not be obtained. When the stretching temperature exceeds 140 ° C, crystallization of PET is promoted and transparency may be deteriorated. When the draw ratio is less than 3.0 times, the strength of the obtained stretched film is low, and pinholes are likely to occur when formed into a bag. When the draw ratio exceeds 5.0 times, stretching becomes difficult. There is a case. Moreover, when the heat treatment temperature is lower than 210 ° C, the heat shrinkage rate of the stretched film obtained is increased, and the bag after bag making may be deformed. When the heat treatment temperature is higher than 245 ° C, the film is blown out. There is a case.

  As the biaxial stretching method, either a tenter simultaneous biaxial stretching method or a sequential biaxial stretching method using a roll and a tenter may be used. Moreover, you may manufacture a biaxially stretched film with a tubular method.

  The polyester film laminate of the present invention is obtained by depositing a metal compound such as silicon oxide or aluminum oxide on at least one side of the biaxially stretched polyester film obtained as described above. These metal compounds deposited on the film can be used alone or in combination. Moreover, as a manufacturing method of a vapor deposition thin film, a vacuum evaporation method, EB evaporation method, sputtering method, an ion plating method, etc. can be used.

  In addition, in order to improve the adhesion between the biaxially stretched polyester film and the deposited film such as aluminum oxide, the surface of the film may be pretreated by a method such as applying a corona discharge treatment or an anchor coating agent in advance. desirable.

  In the present invention, the ink used for forming the printing layer is not particularly limited. Examples include toluene-containing inks, non-toluene inks, and water-based inks. From the viewpoint of the environment, non-toluene ink, water-based ink and the like are preferable.

  In the present invention, the printing layer laminated on the vapor deposition layer is preferably formed with ink added with a silane coupling agent. Examples of the silane coupling agent added to the ink include amino, epoxy, isocyanate, vinyl, and methacryloxy. From the viewpoints of stability and reactivity, amine-based and epoxy-based silane coupling agents are preferred. The addition amount of the silane coupling agent is 0.1 to 5 parts by mass, preferably 0.5 to 4 parts by mass, and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the ink used for printing. If the added amount is less than 0.1 parts by mass, the tearability is not effective. If the added amount exceeds 5 parts by mass, the performance reaches a peak, and at the same time, it is not preferable from the viewpoint of cost.

  The polyester film laminate of the present invention is obtained by laminating at least one kind of film other than the biaxially stretched polyester film in addition to the above-described biaxially stretched polyester film, the vapor deposition layer, and the print layer. For example, when the laminate of the present invention is used for a packaging bag, a film for imparting heat sealability is used as at least one film other than the biaxially stretched polyester film. Specific examples of the film for imparting heat sealability include non-stretched films called sealants such as polyethylene, ethylene-vinyl acetate copolymer, and ionomer. Moreover, when it is desired to obtain further easy tearability in the laminate of the present invention, it can be handled by using an easy tear sealant as at least one film other than the biaxially stretched polyester film. Furthermore, according to the required performance of the laminate of the present invention, for example, a nylon film, a polyester film, a polypropylene film or the like may be laminated. There is no restriction | limiting in particular as a lamination | stacking method of at least 1 type of films other than these biaxially stretched polyester films, Methods, such as a dry lamination method and an extrusion lamination method, are used.

  The polyester film laminate of the present invention needs to have a tear propagation resistance of 1500 mN or less, preferably 1000 mN or less, and more preferably 700 mN. When the tear propagation resistance exceeds 1500 mN, it is necessary to apply an excessive force at the time of tearing, and there is a problem that the contents are scattered depending on the tearing method, and in some cases the tearing is not torn.

  The polyester film laminate of the present invention can be made into a bag to produce a gas barrier easy-open packaging bag. When making a bag, an easy-open packaging bag can be obtained by making the easy tear direction of the laminate the tearing direction of the packaging bag.

  Next, the present invention will be specifically described with reference to examples. In addition, the evaluation method of an Example is as follows.

(1) Tear linearity Using a polyester film laminate, a packaging bag having a longitudinal direction (MD) of 200 mm and a width direction (TD) of 300 mm was prepared. Incisions of 5 mm each on the left and right sides were provided in the TD direction, and the maximum dimension of the deviation width in the MD direction from the notch at the position where 100 mm was torn from the right front to the left front was measured. This operation was performed 5 times. The maximum dimension of the deviation width in the MD direction from the cut portion is less than 5 mm, Δ is 5 mm or more and less than 10 mm, and Δ is 10 mm or more.
(2) Tear propagation resistance (mN)
According to JIS K-7128-1, it measured with respect to the easy tear direction.
(3) Oxygen permeability (ml / m ² · day · MPa)
In accordance with JIS K-7129, measurement was performed under the conditions of a temperature of 20 ° C. and a humidity of 65% RH using an OX-TRAN100 model manufactured by Modern Control.
(4) Water vapor transmission rate (g / m ² · day)
According to JIS K-7129, measurement was performed under the conditions of a temperature of 40 ° C. and a humidity of 90% RH using PARMATRAN W3 / 31 manufactured by Modern Control.
(5) Laminate strength (N / cm)
A polyester film laminate having a width of 15 mm was used as a sample, and peeled at a tensile rate of 300 mm / min in an environment of 20 ° C. × 65% RH, and the laminate strength was measured by a T-type peeling method.

Production Example 1
The manufacturing method of a biaxially stretched polyester film is as follows.
194 parts by mass of dimethyl terephthalate, 108 parts by mass of 1,4-butanediol, and 80 ppm of tetrabutyl titanate (a numerical value converted to the mass of titanium metal with respect to the polymer) were added, and while heating from 150 ° C. to 210 ° C., the temperature was increased to 2.5. The transesterification reaction was performed for a time. After 90 parts by mass of the obtained transesterification reaction product was transferred to a polymerization vessel and 40 ppm of tetrabutyl titanate was added, 10 parts by mass of PTMG having a molecular weight of 1100 was added to obtain a modified PBT having a relative viscosity of 1.60. . A simple chip mixture of PET and modified PBT at a mass ratio of 85/15 was melt extruded at a resin temperature of 280 ° C. using a 200 mmφ extruder equipped with a coat hanger type T die, and the temperature was adjusted to 20 ° C. An applied voltage of 7 kV was applied to the cast roll and the pinning wire was tightly contacted and quenched to obtain an unstretched sheet having a thickness of about 190 μm. The obtained unstretched sheet was stretched 3.5 times at 90 ° C. with a roll longitudinal stretching machine and 4.5 times at 120 ° C. with a tenter transverse stretching machine, and then the transverse relaxation rate was 3% at 235 ° C. It heat-processed and annealed to room temperature, and obtained the biaxially stretched polyester film of thickness 12 micrometers.

The inks used for printing are as follows.
FINE STAR R39 indigo (manufactured by Toyo Ink, non-toluene type)
NEW LP Super R641 White (Toyo Ink Co., Ltd., toluene-containing type)

The silane coupling agent is as follows.
3-aminopropyltrimethoxysilane (KBE-903, manufactured by Shin-Etsu Silicone)

The adhesive / curing agent is as follows.
A968 / A8 (Mitsui Takeda Chemical Co., Ltd.)
TM593 / CAT56 (manufactured by Toyo Morton)

The following three types of sealant films were used for laminating.
TUX-FCS: linear low-density polyethylene film (manufactured by Tosero, thickness 40 μm)
HR-543: Easy tear linear low density polyethylene film (manufactured by KEFI film, thickness 40 μm)
RXC-3: Unstretched polypropylene film (manufactured by Tosero, thickness 40 μm)

Example 1
One side of the film obtained in Production Example 1 was subjected to silicon oxide vapor deposition having a thickness of 500 angstroms by vacuum vapor deposition. Printing was performed on the vapor deposition surface of the obtained silicon oxide vapor-deposited film using a fine star indigo with 2.5 parts by mass of a silane coupling agent added to 100 parts by mass of ink, and the coating amount was 3.0 g / m ^2. Apply TM593 / CAT56 as the adhesive / curing agent to the printing surface, laminate using TUX-FCS as the sealant, and tear the linearity and tear propagation of the film laminate obtained by aging at 40 ° C for 3 days. Table 1 shows the results of measuring resistance, oxygen permeability, water vapor permeability, and laminate strength.

Example 2
Table 1 shows the results of measuring the tear linearity, tear propagation resistance, oxygen permeability, water vapor permeability, and laminate strength of the film laminate obtained in the same manner as in Example 1 except that HR-543 is used as the sealant. Indicated.

Example 3
One side of the film obtained in the same manner as in Production Example 1 except that a modified PBT having a molecular weight of PTMG of 15% by mass and extruding PET and modified PBT at a mass ratio of 90/10 Then, silicon oxide with a thickness of 500 angstroms was deposited by a vacuum deposition method. On the deposition surface of the resulting silicon oxide vapor-deposited film, printing was performed with FINE STAR indigo added with 1.5 parts by mass of a silane coupling agent to 100 parts by mass of ink, and A968 / A8 was applied to the adhesive / curing agent. It is applied in an amount of 3.0 g / m ² , is laminated using RXC-3 as a sealant, and is subjected to aging at 40 ° C. for 3 days. Tear linearity, tear propagation resistance, oxygen permeability, The results of measuring the water vapor transmission rate and the laminate strength are shown in Table 1.

Example 4
Using a modified PBT having a PTMG content of 15% by mass, except that PET and modified PBT were extruded at a mass ratio of 80/20, vacuum deposition was performed on one side of the film obtained as in Production Example 1. The aluminum oxide having a thickness of 500 angstroms was deposited by the above method. On the vapor-deposited surface of the resulting aluminum oxide vapor-deposited film, printing was performed with FINE STAR indigo added with 1.5 parts by mass of a silane coupling agent with respect to 100 parts by mass of ink, and TM593 / CAT56 was applied to the adhesive / curing agent. Coated at a coating amount of 3.0 g / m ² , laminated using HR-543 as a sealant, and a film laminate obtained by aging at 40 ° C. for 3 days, tear linearity, tear propagation resistance, oxygen permeability The results of measuring water vapor permeability and laminate strength are shown in Table 1.

Example 5
It is obtained in the same manner as in Example 4 except that printing is performed with NEW LP Super White in which 1.5 parts by mass of a silane coupling agent is added to 100 parts by mass of ink, and RXC-3 is used as a sealant. Table 1 shows the results of measuring the tear linearity, tear propagation resistance, oxygen permeability, water vapor permeability, and laminate strength of the film laminate.

Example 6
One side of the film obtained as in Production Example 1 except that a modified PBT having a molecular weight of PTMG of 15% by mass was used and PET and modified PBT were extruded at a mass ratio of 85/15. Then, aluminum oxide having a thickness of 500 angstroms was deposited by a vacuum deposition method. On the vapor deposition surface of the resulting aluminum oxide vapor-deposited film, printing is performed with NEW LP Super White in which 1.5 parts by mass of a silane coupling agent is added to 100 parts by mass of ink, and adhesion is performed at a coating amount of 3.0 g / m ² . TM593 / CAT56 was applied to the adhesive / curing agent, the laminate was laminated using HR-543 as the sealant, and the aging was carried out at 40 ° C. for 3 days. The tear linearity, tear propagation resistance, oxygen permeability of the laminated film obtained The results of measuring water vapor permeability and laminate strength are shown in Table 1.

Comparative Example 1
With respect to the laminated film prepared as in Example 1 except that no silane coupling agent was added and HR-543 was used as the sealant, tear linearity, tear propagation resistance, oxygen permeability, water vapor permeability, The results of measuring the laminate strength are shown in Table 1.

Comparative Example 2
Tear linearity, tear propagation resistance, oxygen permeability, water vapor permeability of the laminated film obtained in the same manner as in Comparative Example 1 except that A968 / A8 was used as the adhesive / curing agent and TUX-FCS was used as the sealant. The results of measuring the laminate strength are shown in Table 1.

Comparative Example 3
On one side of the PET film, silicon oxide having a thickness of 500 angstroms was deposited by vacuum deposition. On the vapor deposition surface of the obtained silicon oxide vapor deposition film, printing was performed with FINE STAR indigo added with 2.5 parts by mass of a silane coupling agent with respect to 100 parts by mass of ink, and the adhesive was applied at a coating amount of 3.0 g / m ^2. / A968 / A8 applied to the curing agent, laminated using RXC-3 as the sealant, tearing linearity, tear propagation resistance, oxygen permeability, water vapor of the laminated film obtained by aging at 40 ° C. for 3 days The results of measuring the transmittance and the laminate strength are shown in Table 1.

Claims (4)

A biaxially stretched polyester film, a laminate comprising at least one other film, a vapor deposition layer, and a printed layer, wherein the biaxially stretched polyester film comprises polyethylene terephthalate (PET) and a polyester elastomer, PET / polyester elastomer = manufactured using raw materials mixed at a ratio of 70/30 to 95/5 (mass ratio), and the deposited layer is made of at least one metal compound of aluminum oxide and silicon oxide The vapor barrier layer is laminated on at least one surface of the biaxially stretched polyester film, the printing layer is laminated on the vapor deposition layer surface, and the tear propagation resistance of the laminate is 1500 mN or less, gas barrier property and straight tearing property A polyester film laminate comprising: 2. The polyester film laminate according to claim 1, wherein the polyester elastomer is polybutylene terephthalate (modified PBT) containing 5 to 20% by mass of a polytetramethylene glycol unit having a molecular weight of 600 to 4000. The polyester film laminate according to claim 1 or 2, wherein the printed layer is formed of an ink to which a silane coupling agent is added. A gas barrier easy-open packaging bag produced by using the laminate according to any one of claims 1 to 3 so that the easy tear direction is the tear direction of the bag.