JP6759758B2 - Laminated film, laminate and packaging - Google Patents

Description

The present invention relates to a laminated film having excellent barrier properties and heat-sealing strength, and is particularly suitable for a sealant application having excellent heat-sealing strength with a polyester-based film, and a laminated body and a packaging bag using the same. Regarding.

Conventionally, a laminated film obtained by heat-sealing or laminating a sealant film on a biaxially stretched film as a base film has been used as a packaging material for many of the distribution articles represented by foods, pharmaceuticals and industrial products. The innermost layer of the packaging material constituting the packaging bag, lid material, etc. is provided with a sealant layer made of a polyolefin resin such as polyethylene or polypropylene showing high sealing strength, or a copolymer resin such as ionomer or EMMA. It is known that these resins can achieve high adhesion strength by heat sealing.

However, the non-stretched sealant film made of a polyolefin resin as described in Patent Document 1 is excellent in heat seal strength between polyolefin films, but heat seals with a film made of another material such as polyester. It has the disadvantage of low strength. In addition, since the unstretched sealant film made of polyolefin resin easily adsorbs components made of organic compounds such as fats and oils and fragrances, the packaging material in which the sealant film is the innermost layer, that is, the layer in contact with the contents, has the scent of the contents. It has the disadvantage that it easily changes the taste and taste. Therefore, it is often unsuitable to use a sealant layer made of a polyolefin resin as the innermost layer for packaging chemical products, pharmaceuticals, foods, and the like. Further, since the gas barrier property and the light blocking property are poor, there are cases where deterioration of the contents cannot be sufficiently suppressed.

A polyester-based film as described in Patent Document 2 has excellent gas barrier properties and suppresses deterioration of the contents due to oxygen or the like, and is therefore suitable for applications requiring long-term storage. Furthermore, since the excellent gas barrier property suppresses the odor of the contents from coming out to the outside of the packaging material, it is possible to prevent the solvent odor from drifting to the outside when wrapping the solvent, and conversely, the scent can be trapped. , It is possible to keep the scent of the contents. Further, the polyester-based film is suitable for use as the innermost layer of a packaging material because it does not easily adsorb organic compounds contained in chemical products, pharmaceuticals, foods and the like. However, the polyester-based film described in Patent Document 2 does not have sufficient heat-sealing strength, and it is difficult to use the film as the innermost layer of the packaging material. Further, since the light-shielding property is poor, there are cases where deterioration of the contents due to light cannot be sufficiently suppressed.

Patent Document 3 discloses a polyester-based film for use as a sealant. However, the polyester film of Patent Document 3 has a disadvantage that it has a high heat shrinkage rate. For example, when the film of Example 1 of Patent Document 3 is heat-sealed, there is a problem that the original shape cannot be maintained due to the shrinkage of the sealed portion. Further, since the polyester-based film of Patent Document 3 has low thickness accuracy, there is a problem that missing dots and faint characters occur when printing is performed. Further, if heat treatment is performed to reduce the shrinkage of the film of Patent Document 3, the thickness accuracy is further lowered and devitrification (whitening) occurs due to an increase in haze. It was not possible to obtain a reduced polyester film for sealant use. In addition, deterioration of the contents could not be sufficiently suppressed because the gas barrier property and the light blocking property were not sufficient.

JP-A-2002-256116 Japanese Patent No. 5055660 International Publication No. 2014/175313

An object of the present invention is to solve the above-mentioned problems of the prior art. That is, not only has high heat-sealing strength between the polyester-based laminated films of the present invention, but also excellent heat-sealing strength with a non-stretched polyester-based film made of crystalline polyester and a biaxially stretched polyester-based film made of crystalline polyester. Further, it is an object of the present invention to provide a polyester-based laminated film suitable for sealant applications, which not only does not easily adsorb various organic compounds but also has less shrinkage during heating and is excellent in thickness accuracy, light-shielding property, hygiene property, and gas barrier property. This is the gist of the invention. Further, the present invention is intended to provide a laminate containing at least one layer of a polyester-based laminated film suitable for the above-mentioned sealant application including a metal thin film, and a packaging bag using the same.

The present invention has the following configuration.
1. 1. A laminated film obtained by laminating a metal thin film layer on a base film made of a polyester resin containing at least ethylene terephthalate as a main component, wherein the base film satisfies the following requirements (1) and (2). ..
(1) The base film is composed of two or more layers having at least one heat-sealing layer, and has a heat-sealing layer on the surface layer of any one of the base film surfaces.
(2) In the heat-sealing layer, the total amount (amorphous component amount) of one or more monomer components that can be amorphous components is 12 mol% or more and 30 mol% or less, and the heat-sealed layer The difference in the amount of the amorphous component obtained by subtracting the amount of the amorphous component in the other layers of the base film from the amount of the amorphous component is 4 mol% or more and 30 mol% or less.
2. 2. The main component of the metal film layer is aluminum. The laminated film described in.
3. 3. 1. The thickness of the metal thin film layer is 10 nm or more and 120 nm or less. ~ 2. The laminated film according to any one of.
4. 1. The oxygen permeation amount in an atmosphere of a temperature of 23 ° C. and a relative humidity of 65% RH is 1.0 ml / m ² 24 h MPa or more and 100 ml / m ² 24 h MPa or less. ~ 3. The laminated film according to any one of.
5. The above 1. ~ 4. A packaging bag characterized in that the laminated film according to any one of the above is used for at least a part thereof.
6. The above 1. ~ 4. A laminated body characterized by having at least one layer of the laminated film according to any one of.
7. The above 1. ~ 6. A packaging bag characterized in that at least a part of the laminate described in the above is used.

The polyester-based laminated film of the present invention not only exhibits high heat-sealing strength between itself, but also has a heat-sealing strength with a non-stretched polyester-based film made of crystalline polyester and a biaxially stretched polyester-based film made of crystalline polyester. Is also excellent. Further, since the polyester-based laminated film of the present invention does not easily adsorb various organic compounds, it is possible to hygienically wrap articles containing oils and fragrances such as chemical products, pharmaceuticals and foods. Further, since the film shrinks less when heated, its shape can be maintained even after heat sealing. In addition, the polyester-based laminated film of the present invention has good thickness accuracy and therefore good printability. Further, by including a metal thin film, it has high gas barrier property and light shielding property. By having an excellent gas barrier property, deterioration of the contents due to oxygen outside the packaging material is suppressed. In addition, since the odor of the contents is suppressed from being released to the outside of the packaging material, it is possible to prevent the solvent odor from drifting to the outside when the solvent or the like is wrapped, and conversely, the scent or the like can be trapped. It is possible to keep the scent. Further, it is possible to provide a laminate containing the polyester-based laminated film as at least one layer and a packaging bag using the laminate.

The laminated film of the present invention is a laminated film having at least a base film made of a polyester resin containing ethylene terephthalate as a main component and an aluminum film layer, and is characterized by satisfying the following requirements (1) and (2). It is a film.
(1) The base film is composed of two or more layers having at least one heat-sealing layer, and has a heat-sealing layer on the surface layer of any one of the base film surfaces.
(2) In the heat-sealing layer, the total amount (amorphous component amount) of one or more monomer components that can be amorphous components is 12 mol% or more and 30 mol% or less, and the heat-sealed layer The difference in the amount of the amorphous component obtained by subtracting the amount of the amorphous component in the other layers of the base film from the amount of the amorphous component is 4 mol% or more and 30 mol% or less.

The polyester-based laminated film of the present invention that satisfies the above requirements is a polyester-based laminated film having excellent heat-sealing properties. In particular, it is a film suitable for sealant applications having good heat sealability with a biaxially stretched polyester film made of crystalline polyester and a non-stretched polyester film made of crystalline polyester. Further, since it is difficult to adsorb various organic compounds, it is possible to provide a sealant material suitable as a packaging bag. Further, since the film shrinks less when heated, its shape can be maintained even after heat sealing. In addition, the polyester-based laminated film of the present invention has good thickness accuracy, so that it has good print processability and high transparency. Further, by including an inorganic thin film, it has a high barrier property.
In particular, in the base film, the heat-sealing property and low shrinkage property, and the heat-sealing property and good thickness accuracy are each two contradictory characteristics, and a polyester-based laminated film that can satisfy all of these characteristics has been conventionally used. There wasn't. Hereinafter, the polyester-based laminated film of the present invention will be described.

1. 1. Layer structure of polyester-based laminated film The polyester-based laminated film of the present invention has at least a base film made of a polyester resin containing ethylene terephthalate as a main component and an inorganic thin film layer. The base film must have two or more layers of the film in order to achieve both low shrinkage and heat sealability, and either one of the surface layers must be a heat seal layer. The surface layer of either one of the base film surfaces has a heat seal layer, and the other has an inorganic thin film layer.
The constituent requirements for the heat seal layer and other layers will be described later.
The layer ratio of the heat seal layer in the base film is preferably 20% or more and 80% or less. If the layer ratio of the heat seal layer is less than 20%, the heat seal strength of the film is lowered, which is not preferable. When the layer ratio of the heat-sealing layer is higher than 80%, the heat-sealing property of the film is improved, but the shrinkage rate is higher than 15%, which is not preferable. The layer ratio of the heat seal layer is more preferably 30% or more and 70% or less.
Further, the heat seal layer and the other layers may be provided with a layer subjected to corona treatment, coating treatment, flame treatment, etc. in order to improve the adhesiveness of the film surface, which deviates from the requirements of the present invention. It can be provided arbitrarily as long as it does not.

2. 2. Polyester raw materials constituting the polyester-based base film 2.1. Types of polyester raw materials The polyester used in the present invention contains an ethylene terephthalate unit as a main component.
Further, it is preferable that the polyester used in the present invention contains at least one monomer component that can be an amorphous component (hereinafter, simply referred to as an amorphous component) as a component other than the ethylene terephthalate unit. This is because the heat-sealing strength of the film is improved by the presence of the amorphous component. Since the content of each component differs between the heat seal layer and the other layers, it will be described later. Examples of the monomer of the carboxylic acid component that can be an amorphous component include isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid.
Examples of the monomer of the diol component that can be an amorphous component include neopentyl glycol, 1,4-cyclohexanedimethanol, 2,2-diethyl1,3-propanediol, and 2-n-butyl-2-ethyl-1. , 3-Propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, and hexanediol.
Among these, by using any one or more of isophthalic acid, neopentyl glycol, and 1,4-cyclohexanedimethanol, the amorphousness of the film is enhanced and the heat seal strength can be easily increased to 4N / 15 mm or more. It is more preferable to use any one or more of neopentyl glycol and 1,4-cyclohexanedimethanol, and it is particularly preferable to use neopentyl glycol.

In the present invention, a component other than ethylene terephthalate or an amorphous component may be contained. Examples of the dicarboxylic acid component constituting the polyester include aromatic dicarboxylic acids such as orthophthalic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and decandicarboxylic acid, and alicyclic dicarboxylic acids. .. However, it is preferable that the polyvalent carboxylic acid having a valence of 3 or more (for example, trimellitic acid, pyromellitic acid and their anhydrides) is not contained in the polyester.
Examples of diol components other than ethylene glycol constituting polyester include long-chain diols such as diethylene glycol and 1,4-butanediol, aliphatic diols such as hexanediol, and aromatic diols such as bisphenol A. it can. However, the polyester may not contain a diol having 8 or more carbon atoms (for example, octanediol) or a polyhydric alcohol having 3 or more valences (for example, trimethylolpropane, trimethylolethane, glycerin, diglycerin, etc.). preferable.
Further, as a component constituting the polyester, a polyester elastomer containing ε-caprolactone, tetramethylene glycol or the like may be contained. Since the polyester elastomer has the effect of lowering the melting point of the film, it can be particularly preferably used for the heat seal layer.

In the polyester film of the present invention, various additives such as waxes, antioxidants, antistatic agents, crystal nucleating agents, thickeners, heat stabilizers, coloring pigments, and colorings are used as required. An inhibitor, an ultraviolet absorber, etc. can be added. Further, it is preferable to add fine particles as a lubricant that improves the slipperiness of the film, at least to the surface layer of the film. Any fine particles can be selected. For example, examples of the inorganic fine particles include silica, alumina, titanium dioxide, calcium carbonate, kaolin, barium sulfate, and the like, and examples of the organic fine particles include acrylic resin particles, melamine resin particles, silicone resin particles, and crosslinked polystyrene. Particles and the like can be mentioned. The average particle size of the fine particles can be appropriately selected within the range of 0.05 to 3.0 μm when measured with a Coulter counter, if necessary.
As a method of blending particles into the polyester-based film of the present invention, for example, it can be added at any stage of producing a polyester-based resin, but a polycondensation reaction is carried out at the esterification stage or after the transesterification reaction is completed. It is preferable to add it as a slurry dispersed in ethylene glycol or the like at a stage before the start to proceed with the polycondensation reaction. In addition, a method of blending a slurry of particles dispersed in ethylene glycol, water, or other solvent with a polyester resin raw material using a kneading extruder with a vent, or a method of kneading and extruding dried particles and a polyester resin raw material. There is also a method of blending using a machine.
The preferable amorphous component contained in the heat seal layer will be described below.

2.2. Acrylic component of polyester raw material contained in heat seal layer The polyester used in the heat seal layer of the present invention preferably has an amorphous component content of 12 mol% or more, more preferably 13 mol% or more, and 14 mol% or more. Is particularly preferable. The upper limit of the amount of amorphous components is 30 mol%. The amount of the amorphous component here refers to the total amount of the carboxylic acid or diol monomer component that can be the amorphous component. This means that for one unit of an ester component (one unit in which a carboxylic acid monomer and a diol monomer are connected by an ester bond), if either the acid component or the diol component can be an amorphous component, the ester unit is not. This is because it can be regarded as crystalline.
If the amount of amorphous components in the heat seal layer is lower than 12 mol%, even if the molten resin is extruded from the die and then rapidly cooled and solidified, it will crystallize in the subsequent stretching and heat fixing steps, so the heat seal strength will be 4N. It is not preferable because it becomes difficult to make it / 15 mm or more.
Further, when the total amount of amorphous components in the heat seal layer is 30 mol% or more, the heat seal strength of the film can be increased, but the thickness accuracy of the film is extremely deteriorated, resulting in poor printability. It ends up. Further, if the amount of the amorphous component of the heat seal layer is 30 mol% or more, the heat resistance of the film is lowered, so that the periphery of the seal portion is blocked during heat sealing (intentionally due to heat conduction from the heating member). (Phenomenon that the seal is sealed in a wider range than the specified range), which makes proper heat sealing difficult.

The ethylene terephthalate unit contained in the heat seal layer is preferably 50 mol% or more and 85 mol% or less in 100 mol% of the polyester constituent units. If the ethylene terephthalate unit is less than 50 mol%, the mechanical strength and heat resistance of the film may be insufficient. On the other hand, if the number of ethylene terephthalate units is more than 85 mol, the amount of amorphous components is relatively small, so that it is difficult to set the heat seal strength to 4 N / 15 mm or more.
Further, the amount of the amorphous component contained in the heat-sealed layer of the present invention is 4 mol% or more and 30 mol% or less (the amount of the amorphous component contained in the heat-sealed layer) than the amount of the amorphous component contained in the layer other than the heat-sealed layer. The difference when the amount of the amorphous component contained in the layer other than the heat seal layer is subtracted from the amount is preferably in the range of 4 mol% to 30 mol%). When the difference in the amount of amorphous components is less than 4 mol%, the raw material composition of each layer approaches a single layer, so that the heat seal strength and shrinkage rate of the film cannot be compatible with each other. The difference in the amount of amorphous components is more preferably 4.5 mol% or more. Further, since the upper limit of the amount of the amorphous component contained in the heat seal layer is 30 mol%, the upper limit of the difference in the amount of the amorphous component is 30 mol%.

3. 3. Characteristics of the Polyester-based Laminated Film of the Present Invention Next, the characteristics required for using the polyester-based film of the present invention as a sealant will be described.
3.1. Heat-seal strength First, it is preferable that the heat-seal strength when the polyester-based laminated films of the present invention are heat-sealed at a temperature of 160 ° C., a seal bar pressure of 2 MPa, and a sealing time of 2 seconds is 2N / 15 mm or more and 25N / 15 mm or less. ..
If the heat seal strength is less than 2N / 15 mm, the seal portion is easily peeled off, so that it cannot be used as a packaging bag. The heat seal strength is preferably 2.5 N / 15 mm or more, and more preferably 3 N / 15 mm or more. It is preferable that the heat seal strength is high, but the upper limit that can be obtained at present is about 25 N / 15 mm.
Further, the polyester-based film of the present invention has a heat-sealing strength of 2N / 15 mm or more and 20N / 15 mm or less when the film and a biaxially stretched polyester-based film made of crystalline polyester are heat-sealed at 160 ° C. preferable. If the heat seal strength is less than 2N / 15 mm, the seal portion is easily peeled off, which is not preferable. The heat seal strength is preferably 2.5 N / 15 mm or more, and more preferably 3 N / 15 mm or more. This heat seal strength is preferably high, but the upper limit currently available is about 20 N / 15 mm.
Further, the polyester-based film of the present invention preferably has a heat-sealing strength of 2N / 15 mm or more and 25N / 15 mm or less when heat-sealed with a non-stretched polyester-based film made of crystalline polyester at 160 ° C. If the heat seal strength is less than 2N / 15 mm, it is easily peeled off, which is not preferable. 3.5N / 15mm or more is preferable, and 3N / 15mm or more is more preferable. The heat seal strength is preferably high, but the upper limit currently available is about 25 N / 15 mm.
The heat-sealing strength of the polyester-based laminated film of the present invention varies depending on the mating material, but correlates with the heat-sealing strength of the polyester-based laminated films of the present invention. Therefore, when the term "heat seal strength" is used in the following description, it refers to the heat seal strength between the polyester-based laminated films of the present invention unless otherwise specified.

3.2. Shrinkage rate The polyester-based laminated film of the present invention must have a hot water heat shrinkage rate of 0% or more and 15% or less in both the width direction and the longitudinal direction when treated in hot water at 80 ° C. for 10 seconds. ..
If the shrinkage rate exceeds 15%, the shrinkage becomes large when the film is heat-sealed, and the flatness after sealing deteriorates. The hot water heat shrinkage rate is more preferably 14% or less, and further preferably 13% or less. On the other hand, when the heat shrinkage rate of hot water is less than zero, it means that the film is stretched, which is not preferable because it becomes difficult for the film to maintain its original shape as in the case of a high shrinkage rate.

3.3. Thickness unevenness in the longitudinal direction The polyester-based laminated film of the present invention preferably has a thickness unevenness of 18% or less when the measurement length is 10 m in the longitudinal direction. If the thickness unevenness in the longitudinal direction exceeds 18%, printing defects are likely to occur when printing the film, which is not preferable. The thickness unevenness in the longitudinal direction is more preferably 16% or less, and particularly preferably 14% or less. Further, the smaller the thickness unevenness in the longitudinal direction is, the more preferable it is, but it is considered that the lower limit is about 1% from the performance of the film forming apparatus.

3.4. Thickness unevenness in the width direction In the width direction, the thickness unevenness when the measurement length is 1 m is preferably 18% or less. If the thickness unevenness in the width direction exceeds 18%, printing defects are likely to occur when printing the film, which is not preferable. The thickness unevenness in the width direction is more preferably 16% or less, and particularly preferably 14% or less. It is preferable that the thickness unevenness in the width direction is close to 0%, but the lower limit is considered to be 1% from the viewpoint of the performance of the film forming apparatus and the ease of production.

3.5. Thickness The thickness of the polyester-based laminated film of the present invention is not particularly limited, but is preferably 3 μm or more and 200 μm or less. If the thickness of the film is thinner than 3 μm, the heat seal strength may be insufficient and processing such as printing may become difficult, which is not very preferable. Further, the film thickness may be thicker than 200 μm, but this is not preferable because the weight of the film used increases and the chemical cost increases. The thickness of the film is more preferably 5 μm or more and 160 μm or less, and further preferably 7 μm or more and 120 μm or less.

3.6. Light-shielding property The light-shielding property of the polyester-based laminated film of the present invention is preferably 20% or less when evaluated by the total light transmittance. If the total light transmittance exceeds 20%, it may be difficult to use it in foods, pharmaceuticals, industrial products, etc. that require light shielding properties, which is not very preferable. Further, the lower the light-shielding property, the better, and it is more preferably 10% or less, and further preferably 5% or less.

3.7. Gas barrier property The gas barrier property of the polyester-based laminated film of the present invention is that the oxygen permeation amount in an atmosphere with a temperature of 23 ° C and a relative humidity of 65% RH is 1.0 ml / m ² 24h MPa or more and 100 ml / m ² 24h MPa or less. preferable. If the gas barrier property exceeds 100 ml / m ² 24h MPa, it may be difficult to use it in foods, pharmaceuticals and industrial products, which is not very preferable. The lower the gas barrier property, the better, but at the current state of the art, the lower limit of the barrier property in this configuration is 1.0 ml / m ² 24 h MPa, and even 1.0 ml / m ² 24 h MPa is practically sufficient. I can say.

4. Film formation conditions for polyester-based base film 4.1. Melt extrusion The polyester-based base film of the present invention has the above 2. The polyester raw material described in "Polyester raw material constituting the raw material of the polyester-based base film" is melt-extruded by separate extruders in the heat seal layer and the other layers to form an unstretched laminated film, which is then formed. It can be obtained by uniaxial stretching or biaxial stretching by a predetermined method shown below. The film obtained by biaxial stretching is more preferable. As described above, the polyester can be obtained by polycondensing by selecting the type and amount of the dicarboxylic acid component and the diol component so as to contain an appropriate amount of a monomer that can be an amorphous component. Further, two or more kinds of chip-shaped polyester can be mixed and used as a raw material for a film.
When the raw material resin is melt-extruded, it is preferable to dry the polyester raw material of each layer using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer. After the polyester raw material of each layer is dried in this way, it is melted at a temperature of 200 to 300 ° C. using an extruder and extruded as a laminated film. For extrusion, any existing method such as a T-die method or a tubular method can be adopted.
Then, the unstretched laminated film can be obtained by quenching the laminated film melted by extrusion. As a method for rapidly cooling the molten resin, a method of casting the molten resin from a base onto a rotating drum and quenching and solidifying the molten resin to obtain a substantially unoriented resin sheet can be preferably adopted. The film may be stretched in at least one of the longitudinal (longitudinal) direction and the horizontal (width) direction. In the following, the sequential biaxial stretching method by longitudinal stretching-transverse stretching in which longitudinal stretching is first performed and then transverse stretching will be described. However, even in the case of transverse stretching-longitudinal stretching in which the order is reversed, the main orientation direction is It doesn't matter because it only changes. Further, the simultaneous biaxial stretching method may be used.

4.2. Longitudinal stretching For stretching in the longitudinal direction, it is preferable to introduce the non-stretched film into a longitudinal stretching machine in which a plurality of roll groups are continuously arranged. In the longitudinal stretching, it is preferable to preheat the film with a preheating roll until the film temperature reaches 65 ° C. to 90 ° C. If the film temperature is lower than 65 ° C., it becomes difficult to stretch the film when it is stretched in the vertical direction, and breakage is likely to occur, which is not preferable. Further, if the temperature is higher than 90 ° C., the film tends to adhere to the roll, and the film is easily wrapped around the roll or the roll is easily soiled due to continuous production, which is not preferable.
When the film temperature reaches 65 ° C. to 90 ° C., longitudinal stretching is performed. The longitudinal stretching ratio is preferably 1 to 5 times or less. Since 1x is not longitudinally stretched, the longitudinal stretching ratio is 1x to obtain a horizontally uniaxially stretched film, and 1.1 times or more is required to obtain a biaxially stretched film. The upper limit of the longitudinal stretching ratio may be any number, but if the longitudinal stretching ratio is too high, it becomes difficult to laterally stretch and fracture is likely to occur, so it is preferably 5 times or less.
Further, by relaxing the film in the longitudinal direction after longitudinal stretching (relaxation in the longitudinal direction), the shrinkage rate in the longitudinal direction of the film caused by the longitudinal stretching can be reduced. Furthermore, the Boeing phenomenon (distortion) that occurs in the tenter can be reduced by relaxing in the longitudinal direction. Since the polyester-based film of the present invention uses an amorphous raw material, it is considered that the shrinkage in the longitudinal direction caused by longitudinal stretching is dominant for Boeing strain. This is because in the lateral stretching and final heat treatment in the subsequent process, both ends in the film width direction are gripped and heated, so that only the central portion of the film shrinks in the longitudinal direction. The relaxation rate in the longitudinal direction is preferably 0% or more and 70% or less (a relaxation rate of 0% means that relaxation is not performed). Since the upper limit of the relaxation rate in the longitudinal direction is determined by the raw materials used and the longitudinal stretching conditions, relaxation cannot be performed beyond this. In the polyester film of the present invention, the relaxation rate in the longitudinal direction is up to 70%. Relaxation in the longitudinal direction can be performed by heating the film after longitudinal stretching at a temperature of 65 ° C. to 100 ° C. or lower and adjusting the speed difference of the rolls. As the heating means, any of roll, near infrared ray, far infrared ray, hot air heater and the like can be used. Further, relaxation in the longitudinal direction can be performed not immediately after longitudinal stretching, but also in lateral stretching (including preheating zone) and final heat treatment by narrowing the clip interval in the longitudinal direction (in this case, both ends in the film width direction). (Because it is relaxed in the longitudinal direction, Boeing distortion is reduced), it can be performed at any time.
After relaxing in the longitudinal direction (longitudinal stretching if not relaxing), it is preferable to cool the film once, and it is preferable to cool it with a cooling roll having a surface temperature of 20 to 40 ° C.

4.3. Lateral Stretching After the longitudinal stretching, it is preferable to carry out the transverse stretching at a stretching ratio of about 3.5 to 5 times at 65 ° C. to 110 ° C. while holding both ends of the film in the width direction with clips in the tenter. Preheating is preferably performed before stretching in the lateral direction, and the preheating is preferably performed until the film surface temperature reaches 75 ° C. to 120 ° C.
After transverse stretching, it is preferable to pass the film through an intermediate zone where no aggressive heating operation is performed. Since the temperature is higher in the next final heat treatment zone than in the transverse stretching zone of the tenter, the heat of the final heat treatment zone (hot air itself or radiant heat) will flow into the transverse stretching process unless the intermediate zone is provided. In this case, since the temperature of the laterally stretched zone is not stable, not only the thickness accuracy of the film deteriorates, but also the physical properties such as heat seal strength and shrinkage rate vary. Therefore, it is preferable that the film after the transverse stretching is passed through the intermediate zone and a predetermined time has passed, and then the final heat treatment is performed. In this intermediate zone, when a strip of paper is hung without passing through the film, the strip-shaped piece of paper hangs down almost completely in the vertical direction, so that the accompanying flow accompanying the running of the film, the lateral stretching zone, and the final It is important to block hot air from the heat treatment zone. The transit time of the intermediate zone is sufficient to be about 1 second to 5 seconds. If it is shorter than 1 second, the length of the intermediate zone becomes insufficient and the heat blocking effect is insufficient. On the other hand, it is preferable that the intermediate zone is long, but if it is too long, the equipment will become large, so about 5 seconds is sufficient.

4.4. Final heat treatment After passing through the intermediate zone, it is preferable to perform heat treatment in the final heat treatment zone at a transverse stretching temperature of 180 ° C. or lower. If the heat treatment temperature is not equal to or higher than the transverse stretching temperature, the effect of the heat treatment will not be exhibited. In this case, the shrinkage rate of the film at 80 ° C. is higher than 15%, which is not preferable. The higher the heat treatment temperature, the lower the shrinkage rate of the film, but if it is higher than 180 ° C., the haze of the film becomes higher than 15% and the transparency cannot be maintained, which is not preferable.
At the time of the final heat treatment, the shrinkage ratio in the width direction can be reduced by reducing the distance between the clips of the tenter at an arbitrary magnification (relaxation in the width direction). Therefore, in the final heat treatment, it is preferable to relax in the width direction in the range of 0% or more and 10% or less (a relaxation rate of 0% means that relaxation is not performed). The higher the relaxation rate in the width direction, the lower the shrinkage rate in the width direction, but the upper limit of the relaxation rate (shrinkage rate in the width direction of the film immediately after lateral stretching) is the raw material used, the stretching conditions in the width direction, and the heat treatment temperature. It is not possible to carry out relaxation beyond this, as it is determined by. In the polyester-based base film of the present invention, the relaxation rate in the width direction is limited to 10%.
The passage time of the final heat treatment zone is preferably 2 seconds or more and 20 seconds or less. If the passing time is 2 seconds or less, the surface temperature of the film passes through the heat treatment zone without reaching the set temperature, which makes the heat treatment meaningless. The longer the transit time, the higher the effect of the heat treatment. Therefore, it is preferably 2 seconds or longer, and more preferably 5 seconds or longer. However, if the transit time is to be lengthened, the equipment will become huge, so 20 seconds or less is sufficient for practical use.
After that, a polyester-based base film roll can be obtained by winding while cutting and removing both ends of the film.

5. Film formation conditions for a metal thin film In order to exhibit sufficient gas barrier properties and light-shielding properties, it is necessary to form a metal thin film on the polyester-based base film roll. The metal thin film layer is preferably a thin film layer whose main component is aluminum in terms of workability and the like. In addition, other components may be contained as long as this characteristic is not lost. The film thickness of the thin film is not particularly limited, but is preferably 10 to 120 nm, and more preferably 20 to 100 nm from the viewpoint of gas barrier properties. If it is thinner than 10 nm, it is difficult to develop sufficient barrier properties, and the light-shielding properties deteriorate. Further, even if the thickness is thicker than 100 nm, there is no corresponding effect of improving the gas barrier property, which is rather disadvantageous in terms of manufacturing cost.
A known production method can be used as long as the object of the present invention is not impaired. For example, a PVD method (physical vapor deposition method) such as a vacuum vapor deposition method, a sputtering method, and ion plating, or a CVD method (chemical vapor deposition method) can be mentioned. In particular, the vacuum deposition method is preferable from the viewpoint of production speed and stability. As the heating method, resistance heating, high frequency induction heating, electron beam heating and the like can be used. Further, the film forming conditions may be changed as long as the object of the present invention is not impaired, such as applying a bias to the substrate, raising the substrate temperature, or cooling the substrate.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the aspects of such Examples, and may be appropriately modified without departing from the spirit of the present invention. Is possible.
The evaluation method of the film is as follows. If the longitudinal direction and the width direction cannot be specified immediately due to the small area of the film, the longitudinal direction and the width direction may be determined and the measurement may be performed, and the temporarily determined longitudinal direction and the width direction become the true direction. On the other hand, the difference of 90 degrees does not cause any problem.

<Film evaluation method>
[Heat seal strength]
The heat seal strength was measured according to JIS Z1707. The specific procedure is briefly shown. With a heat sealer, the heat-sealed surfaces that had not been coated or corona-treated were bonded to each other. The sealing conditions were an upper bar temperature of 160 ° C., a lower bar temperature of 100 ° C., a pressure of 2 kg / cm2, and a time of 2 seconds. The adhesive sample was cut out so that the seal width was 15 mm. The peel strength was measured at a tensile speed of 200 mm / min using a universal tensile tester "DSS-100" (manufactured by Shimadzu Corporation). The peel strength is indicated by the strength per 15 mm (N / 15 mm).
The biaxially stretched polyester film used in the heat seal strength measurement with the biaxially stretched polyester film made of crystalline polyester was E5100-12 μm (manufactured by Toyo Boseki Co., Ltd.), and the non-stretched polyester film made of crystalline polyester. The non-stretched polyester film used in the heat seal strength measurement of A-PET-30 μm (manufactured by Toyo Boseki Co., Ltd.).

[Hot water heat shrinkage rate]
The film was cut into 10 cm × 10 cm squares, immersed in warm water at 80 ± 0.5 ° C. for 10 seconds under no load to shrink, and then immersed in water at 25 ° C. ± 0.5 ° C. for 10 seconds. I took it out of the water. Then, the vertical and horizontal dimensions of the film were measured, and the shrinkage ratio in each direction was determined according to the following formula 1. The measurement was performed twice, and the average value was calculated.

Shrinkage rate = {(length before contraction-length after contraction) / length before contraction} x 100 (%) Equation 1

[Haze]
The measurement was performed using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., 300A) in accordance with JIS-K-7136. The measurement was performed twice, and the average value was calculated.

[Thickness unevenness in the longitudinal direction]
The film was sampled in a roll shape of 11 m in the longitudinal direction and 40 mm in the width direction, and the measurement speed was 5 m / min using a continuous contact type thickness gauge manufactured by Micron Measuring Instruments Co., Ltd. The thickness was continuously measured along the longitudinal direction of the film (measurement length was 10 m). The maximum thickness at the time of measurement was Tmax., The minimum thickness was Tmin., And the average thickness was Tave., And the thickness unevenness in the longitudinal direction of the film was calculated from the following equation 2.

Thickness unevenness = {(Tmax.-Tmin.)/Tave.} × 100 (%) ・ ・ Equation 2

[Thickness unevenness in the width direction]
The film was sampled into a wide strip of 40 mm in length and 1.2 m in width, and the measurement speed was 5 m / min using a continuous contact type thickness gauge manufactured by Micron Measuring Instruments Co., Ltd. The thickness was continuously measured along the width direction of the film sample (measurement length was 1 m). The maximum thickness at the time of measurement was Tmax., The minimum thickness was Tmin., And the average thickness was Tave., And the thickness unevenness in the longitudinal direction of the film was calculated from the above equation 2.

[Light blocking effect]
The light-shielding property was evaluated by the total light transmittance of the film. The total light transmittance was evaluated using a haze meter (NGH500 manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

[Gas barrier property]
The oxygen permeation amount was measured in an atmosphere of a temperature of 23 degrees and a humidity of 65% RH by preparing an oxygen permeation amount measuring device (manufactured by OXTRAN 2/21 MOCOM) according to the JIS K7126-2A method. The amount of oxygen permeated was measured in the direction in which oxygen permeated from the heat-sealed layer side of the surface layer to the inorganic thin film layer side.

[Film thickness of inorganic thin film]
A sample cut out to a size of 1 mm × 10 mm was wrapped in an epoxy resin for an electron microscope and then fixed in a sample holder of an ultramicrotome to prepare a thin section having a cross section parallel to the short side of the wrapped sample piece. Next, observation was performed using a transmission electron microscope (JEM2010, manufactured by JEOL Ltd.) at a site where the section thin film was not significantly damaged. After observing at an accelerating voltage of 200 kV and 20000 times, the film thickness of each layer was measured at 100 points, and the average was taken as the film thickness.

<Preparation of polyester raw material>
[Synthesis Example 1]
A stainless steel autoclave equipped with a stirrer, a thermometer and a partial recirculation cooler contains 100 mol% of dimethyl terephthalate (DMT) as a dicarboxylic acid component and 100 mol% of ethylene glycol (EG) as a polyhydric alcohol component. Ethylene glycol was charged so as to be 2.2 times the molar ratio of dimethyl terephthalate, and 0.05 mol% (relative to the acid component) of zinc acetate was used as a transesterification catalyst to distill off the produced methanol. While doing so, the transesterification reaction was carried out. Then, 0.225 mol% of antimony trioxide (relative to the acid component) was added as a polycondensation catalyst, and the polycondensation reaction was carried out at 280 ° C. under a reduced pressure of 26.7 Pa to obtain an intrinsic viscosity of 0.75 dl / g. Polyester (A) was obtained. This polyester (A) is polyethylene terephthalate. The composition of the polyester (A) is shown in Table 1.
[Synthesis Example 2]
Polyesters (B) to (E) having different monomers were obtained in the same procedure as in Synthesis Example 1. The composition of each polyester is shown in Table 1. In Table 1, TPA is terephthalic acid, BD is 1,4-butanediol, NPG is neopentyl glycol, CHDM is 1,4-cyclohexanedimethanol, and DEG is diethylene glycol. In the production of the polyester (E), SiO2 (Silicia 266 manufactured by Fuji Silysia Chemical Ltd.) was added as a lubricant at a ratio of 7,000 ppm to the polyester. Each polyester was appropriately formed into chips.
[Evaluation film]
The films used other than the films shown in the examples of this patent are a commercially available 30 μm unstretched polypropylene-based film for sealants and a commercially available 30 μm polyacrylonitrile-based film for sealants.

[Example 1]
Polyester A, polyester B, polyester D, and polyester E are mixed as raw materials for the heat seal layer (A layer) at a mass ratio of 10:75: 10: 5, and polyester A and polyester are used as raw materials for the other layers (B layer). B, polyester D and polyester E were mixed at a mass ratio of 55:30: 10: 5.
The mixed raw materials of the A layer and the B layer were put into separate twin-screw extruders, and both were melted at 270 ° C. Each molten resin was joined by a feed block in the middle of the flow path, discharged from a T-die, and cooled on a chill roll set to a surface temperature of 30 ° C. to obtain an unstretched laminated film. The flow path of the molten resin is set so that both surface layers of the laminated film are A layer and the central layer is B layer (2 types of 3 layers of A layer / A layer / A layer), and the thickness of A layer and B layer. The discharge amount was adjusted so that the ratio was 50:50.
The unstretched laminated film obtained by cooling and solidifying is guided to a longitudinal stretching machine in which a plurality of roll groups are continuously arranged, preheated on preheating rolls until the film temperature reaches 90 ° C., and then stretched 4.1 times. did. The film immediately after longitudinal stretching was passed through a heating furnace set at 95 ° C. with a hot air heater, and a 20% relaxation treatment was performed in the longitudinal direction by utilizing the speed difference between the rolls at the inlet and the outlet of the heating furnace. Then, the vertically stretched film was forcibly cooled by a cooling roll set to a surface temperature of 25 ° C.
The film after the relaxation treatment was guided to a transverse stretching machine (tenter), preheated for 5 seconds until the surface temperature reached 95 ° C., and then stretched 4.0 times in the width direction (lateral direction). The film after the transverse stretching was directly led to the intermediate zone and passed in 1.0 second. In the intermediate zone of the tenter, the hot air from the final heat treatment zone and the lateral stretching zone so that when the strip-shaped piece of paper hangs down without passing through the film, the piece of paper hangs down almost completely in the vertical direction. The hot air from was cut off.
Then, the film that passed through the intermediate zone was led to the final heat treatment zone and heat-treated at 115 ° C. for 5 seconds. At this time, the heat treatment was performed and at the same time, the clip interval in the film width direction was narrowed to perform a 3% relaxation treatment in the width direction. After passing through the final heat treatment zone, the film was cooled, both edges were cut and removed, and the film was wound into a roll with a width of 500 mm to continuously produce a biaxially stretched film having a thickness of 30 μm over a predetermined length. ..
Particulate aluminum (purity 99.5%) having a size of about 3 to 5 mm is used as a vapor deposition source on the biaxially stretched film, and one electron gun (hereinafter referred to as an EB gun) is used as a heating source. An aluminum thin film was formed.
The properties of the obtained film were evaluated by the above method. The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 3.

[Example 2]
The raw materials for the A layer and the B layer used the same polyester raw materials as in Example 1, and were not stretched under the same conditions as in Example 1 except that the discharge amount was adjusted so that the film thickness after biaxial stretching was 12 μm. A laminated film was obtained. Then, a film was formed under the same conditions as in Example 1 to obtain a biaxially stretched film having a width of 500 mm and a thickness of 12 μm. The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 3.

[Example 3]
The raw materials of the A layer and the B layer were the same polyester raw materials as in Example 1, and were not stretched under the same conditions as in Example 1 except that the discharge amount was adjusted so that the film thickness after biaxial stretching was 60 μm. A laminated film was obtained. Then, a film was formed under the same conditions as in Example 1 to obtain a biaxially stretched film having a width of 500 mm and a thickness of 60 μm. The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 3.

[Example 4-9]
The film was formed under the same conditions as in Example 1 except that the film thickness of the aluminum thin film was changed by changing the feed rate of the film when the aluminum thin film was formed. The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 3.

[Comparative Example 1]
A metal thin film was formed on a commercially available unstretched polypropylene film for sealant having a thickness of 30 μm by the same method as in Example 1, and then evaluated by the above method. The evaluation results are shown in Table 3.

[Comparative Example 2]
A metal thin film was formed on a commercially available polyacrylonitrile-based film for sealant having a thickness of 30 μm by the same method as in Example 1, and then evaluated by the above method. The evaluation results are shown in Table 3.

[Comparative Example 3]
A copolymer of polyethylene isophthalate and polyethylene terephthalate having a melting point of 218 ° C. as a raw material for layer B, and polyethylene terephthalate having a melting point of 265 ° C. containing 1000 ppm of silica particles having an average particle diameter of 1.5 μm as a raw material for layer A. Melted by separate extruders at a temperature of ° C, the melts are merged with a composite adapter, extruded from a T-die, and rapidly cooled with a cooling drum at 30 ° C to form a three-layer unstretched laminated film with a B / A / B structure. Got The unstretched laminated film is first preheated to 95 ° C. using a metal roll, further heated using three infrared heaters having a surface temperature of 750 ° C., stretched 1.5 times at 115 ° C. in the vertical direction, and further rolled. After cooling and heating the film to 95 ° C., the film was stretched three times in the longitudinal direction. The film is then preheated to 110 ° C in a tenter and laterally 110 ° C.
After stretching 4.0 times while raising the temperature to 150 ° C, then stretching 1.1 times while raising the temperature to 223 ° C, and performing heat treatment at 223 ° C while keeping the width direction constant, 223. A 30 μm film was obtained by performing a relaxation treatment of 3% in the width direction while lowering the temperature from ° C. to 150 ° C. The thickness ratio of each B / A / B layer of this film was 4/92/4, respectively. A metal thin film was formed on the film by the same method as in Example 1. The evaluation results are shown in Table 3.

[Comparative Example 4]
The film was formed by the same method as in Example 1 except that the aluminum thin film was not formed. The evaluation results are shown in Table 3.

The present invention relates to a polyester-based laminated film having excellent heat-sealing strength and gas barrier properties, and not only has excellent heat-sealing strength with a polyester-based film, but also has less shrinkage during heating, and has thickness accuracy, light-shielding properties, and so on. It has excellent gas barrier properties and can be suitably used as a sealant. Further, the polyester-based laminated film of the present invention may be used as at least one layer to form a laminated body with another film, and a packaging bag can be provided from the laminated body.

Claims (7)

In a laminated film in which a metal thin film layer is laminated on a base film made of a polyester resin containing at least ethylene terephthalate as a main component, the base film satisfies the following requirements (1) and (2) and measures the length in the longitudinal direction. A laminated film characterized in that the thickness unevenness when the measurement length is 10 m and the thickness unevenness when the measurement length is 1 m in the width direction are both 18% or less.
(1) The base film is composed of two or more layers having at least one heat-sealing layer, and has a heat-sealing layer on the surface layer of any one of the base film surfaces.
(2) The total amount (amorphous component amount) of one or more monomer components that can be amorphous components in the heat seal layer is 13 mol% or more and 30 mol% or less, and becomes the amorphous component. The obtained monomer components are isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, neopentyl glycol, 1,4-cyclohexanedimethanol, 2,2-diethyl1,3-propanediol, 2-. Consists of n-butyl-2-ethyl-1,3-propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, and hexanediol Selected from the group, the amount of the amorphous component of the layer other than the heat-sealed layer of the base film is 8.8 mol% or more, and the amount of the amorphous component of the heat-sealed layer is determined from the amount of the amorphous component of the base film. The difference in the amount of the amorphous component obtained by subtracting the amount of the amorphous component is 4 mol% or more. The laminated film according to claim 1, wherein the main component of the metal film layer is aluminum. The laminated film according to any one of claims 1 and 2, wherein the thickness of the metal thin film layer is 10 nm or more and 120 nm or less. Claims 1 to 3, wherein the oxygen permeation amount in an atmosphere of a temperature of 23 ° C. and a relative humidity of 65% RH is 1.0 ml / m ² 24 h MPa or more and 100 ml / m ² 24 h MPa or less. The laminated film according to any one of. A packaging bag comprising the laminated film according to any one of claims 1 to 4 at least in part. A laminated body comprising the laminated film according to any one of claims 1 to 4 as at least one layer. A packaging bag comprising the laminate according to claims 1 to 6 at least in part.