JP2000318079A - Multilayered stretched film and stretched polyethylene-2,6-naphthalate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered stretched film well keeping stretchability and thickness irregularity, reduced in cutting in a separation process and excellent in productivity, and a first polymer layer peeled from the multilayered stretched film. SOLUTION: In a multilayered stretched film wherein at least one first polymer layer comprising a thermoplastic resin and at least one second polymer layer comprising a thermoplastic resin incompatible with the first polymer layer are adjacent to each other and the interlaminar strength of these two layers is 0.1-20 g/cm and at least one outermost layer comprises the first polymer layer and the first and second polymer layers are present alternately, the thickness of the first polymer layer is 1-5 μm and that of the second polymer layer is 3-10 μm and the melt viscosity of the thermoplastic resin constituting the first polymer layer at 280 deg.C and a shearing speed of 100 sec-1 is higher than that of the thermoplastic resin constituting the second polymer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer stretched film in which mutually incompatible polymer layers are laminated adjacently, and a stretched polyethylene-2,6-naphthalate film (single-layer film) obtained by peeling off the multilayer stretched film. More specifically,
Multi-layer stretched film with less delamination and cutting in the manufacturing process and less cutting of each layer when separating and separating a single-layer film, and thermal transfer printer ribbon with good thickness unevenness and few surface defects obtained by peeling from it Polyethylene having suitable surface properties for base film
It relates to a 2,6-naphthalate film.

[0002]

2. Description of the Related Art A polyester film has mechanical properties,
It has excellent properties such as dimensional stability and heat resistance, and has been used in many fields to date. One of them is the use as a base film of a thermal transfer printer ribbon (thermal transfer ribbon).

[0003] In recent years, as the printing speed of a thermal transfer printer has been required to be increased, the temperature of a thermal head for printing has increased, resulting in an increase in the amount of heat received by the thermal transfer ribbon. High heat resistance is required for films. On the other hand, in order to increase the printing speed, it is necessary to improve the heat transfer of the thermal transfer ribbon, and it is necessary to reduce the thickness of the ribbon. Therefore, a thin film having high strength and high Young's modulus is desired for the base film in addition to heat resistance.

[0004] Base films for thermal transfer ribbons include:
Conventionally, a polyethylene terephthalate film has been used. However, in order to produce a thin, high-strength, high Young's modulus polyethylene terephthalate film that satisfies recent requirements, it is necessary to stretch the film at a higher magnification than before, and the resulting film is extremely thin, Problems occur such as frequent cutting in the manufacturing process, and poor handling in the processing process.

In order to alleviate such a problem, a multi-layer film in which a carrier film of a material incompatible with polyethylene terephthalate is laminated and reinforced is processed, and after the processing is completed, the polyethylene terephthalate film is peeled off from the carrier film to form a product film. (JP-A-64-14092, JP-A-04-71)
No. 98 publication) has been proposed.

[0006] Japanese Patent Application Laid-Open No. Sho 60-178031 discloses a method for producing an ultrathin polyethylene terephthalate film in which the intrinsic viscosity and melting point of polypropylene used for a carrier film of a multilayer film are specified, and the cut and uneven thickness are excellent. It has been proposed.

Further, as a method of obtaining an ultra-thin polyethylene-2,6-naphthalate film for use in a capacitor or the like, a polyethylene-2,6-naphthalate film is prepared from a multilayer film of polyethylene-2,6-naphthalate and ethylene copolymerized polypropylene. Method for obtaining a film
No. 62136) has also been proposed.

[0008]

However, the prior art has the following problems. Since the multilayer stretched film as described above has a low interlayer adhesive strength, there is a problem in the manufacturing process such that the film is easily delaminated or cut on a roll in the step of longitudinal stretching.

When a polyethylene terephthalate film obtained by peeling from a multilayer stretched film as described above is used as a base film for a thermal transfer ribbon, there are a number of crater-like transfer defects on the surface peeled from the carrier film. This is a serious surface defect such as adversely affecting printing.

Further, when the above-mentioned polyethylene-2,6-naphthalate film obtained by peeling off the polyethylene-2,6-naphthalate and ethylene copolymerized polypropylene multilayer stretched film is used as a base film for a thermal transfer ribbon. , In addition to the crater-like transfer defect,
The surface peeled from the carrier film becomes too smooth, resulting in poor film winding properties, poor coating properties of the ink layer and the back coat layer (anti-fusing layer), and also poor running properties of the thermal transfer ribbon. There is.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that a thermoplastic resin having a specific melt viscosity is used as a resin constituting the first polymer layer and the second polymer layer. In the case of a multilayer film having a specific thickness of the polymer layer, it is found that a multilayer film can be obtained with less delamination in the manufacturing process of the multilayer film and less cutting when separating and separating the single-layer film from the multilayer film. This has led to the present invention. Furthermore, the inventors have found that a single-layer film obtained by peeling from the above-mentioned multilayer film has few defects on the peeled surface and has particularly excellent surface characteristics as a base film of a ribbon for thermal transfer, and has reached the present invention.

That is, according to the present invention, at least one layer of a first polymer layer made of a thermoplastic resin and at least one layer of a second polymer layer made of a thermoplastic resin incompatible with the polymer layer are adjacent to each other, The interlayer adhesion between these two layers is in the range of 0.1 to 20 g / cm, at least one of the outermost layers is composed of the first polymer layer, and the second polymer layer and the first polymer layer are present alternately. A multilayer stretched film, wherein the thickness of the first polymer layer is in the range of 1 to 5 μm,
The thickness of the second polymer layer is in the range of 3 to 10 μm, and the shear rate at 280 ° C. of the resin constituting the first polymer layer is 1
It is a multi-layer stretched film, wherein the melt viscosity at 00sec ^-1 is high viscosity than the melt viscosity at a shear rate 100 sec ^-1 at 280 ° C. of the resin constituting the second polymer layer.

[0013] The present invention also relates to a polyethylene film obtained by peeling the first polymer layer from the multilayer stretched film.
A 2,6-naphthalate film, having a major axis of 5 to 20 μm present on the release surface of the film from the second polymer layer;
m is a stretched polyethylene-2,6-naphthalate film having 30 or less crater-shaped defects per 4 mm square.
Hereinafter, the present invention will be described in detail.

[Resin Constituting First Polymer Layer] In the present invention, the thermoplastic resin constituting the first polymer layer is:
280 incompatible with the resin constituting the second polymer layer
The melt viscosity at a shear rate of 100 sec ^-1
Shear rate at 280 ° C. of the resin constituting the polymer layer is 10
It is a thermoplastic resin having a higher viscosity than the melt viscosity at ⁰ sec ^-1 .

As such a thermoplastic resin, a linear polyester is preferable. In particular, polyethylene-2,6-naphthalate containing ethylene-2,6-naphthalenedicarboxylate as a main repeating unit is peeled off and separated from the multilayer film. Even if the obtained single-layer film is thin, heat resistance, strength, and Young's modulus are excellent, which is preferable.

As the polyethylene-2,6-naphthalate used in the present invention, it is necessary to select a polyethylene-2,6-naphthalate having a higher melt viscosity at a shear rate of 100 sec ^-1 at 280 ° C. than that of the thermoplastic resin constituting the second polymer layer. It is. For example, the thermoplastic resin constituting the second polymer layer is MFR
In the case of an ethylene copolymerized polypropylene of 0.5 or more, polyethylene-2,6-naphthalate preferably has a melt viscosity at 280 ° C. and a shear rate of 100 sec ⁻¹ of 500 Pa · s or more, particularly preferably 600 Pa · s or more.

The polyethylene-2,6-naphthalate may contain a copolymer component in such a proportion that the Young's modulus in the longitudinal direction of the film can be satisfied when the film is used as a base film for a thermal transfer ribbon. .

As the copolymerization component, a compound having two ester-forming functional groups, for example, oxalic acid, adipic acid,
Phthalic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, terephthalic acid, 2-potassium sulfoterephthalic acid,
2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, phenylindanedicarboxylic acid, diphenyletherdicarboxylic acid and lower alkyl esters thereof;
Oxycarboxylic acids such as p-oxyethoxybenzoic acid and lower alkyl esters thereof; propylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, , 6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylylene glycol, ethylene oxide adduct of bisphenol A, ethylene oxide adduct of bisphenol S Body, diethylene glycol, triethylene glycol,
Examples include polyethylene oxide glycol, polytetramethylene oxide glycol, neopentyl glycol and the like.

Polyethylene-2,6-naphthalate is obtained by blocking a terminal hydroxyl group and / or a carboxyl group partially or entirely with a monofunctional compound such as naphthoic acid, benzoic acid or methoxypolyalkylene glycol. Alternatively, it may be modified with a very small amount of an ester-forming compound having three or more functional groups such as glycerin and pentaerythritol within a range where a substantially linear polymer can be obtained.

The thermoplastic resin constituting the first polymer layer according to the present invention may contain additives such as stabilizers, dyes, lubricants, ultraviolet absorbers, and flame retardants, if desired. Also, if necessary, a lubricant, an antioxidant, an antistatic agent, a colorant, a pigment, a tendency brightener, a plasticizer,
UV absorbers, other resins and the like can be added.

The thermoplastic resin constituting the first polymer layer has a volume resistivity in a molten state at a temperature higher by 15 ° C. than the melting point (Tm) of 0.5 × 10 ⁹ Ω · m under the measurement condition of an AC voltage of 50 Hz. cm or less.
When the volume resistivity is in this range, the application of electrostatic charge to the multilayer film during casting becomes strong, and the adhesion between the cooling drum and the multilayer film becomes good.

The thermoplastic resin having such a volume resistivity can be obtained, for example, by blending a compound having an alkali metal salt or by copolymerizing a quaternary phosphonium salt of sulfonic acid. Good adhesion to the drum can be obtained.

[Resin Constituting the Second Polymer Layer]
The thermoplastic resin forming the second polymer layer is
Incompatible with the resin constituting one polymer layer, 280 ° C
Shearing speed 100sec^-1The melt viscosity at
Shear rate at 280 ° C. of the resin constituting the limmer layer is 100
sec ^-1Thermoplastic resin with lower viscosity than melt viscosity
is there.

As such a thermoplastic resin, a polyolefin is preferable, and in particular, the first polymer layer is made of polyethylene.
In the case of 2,6-naphthalate, an ethylene copolymerization ratio of 3
Preferred is ethylene copolymerized polypropylene having a MFR of 0.5 to 50 g / 10 min.

If the ethylene copolymerization ratio of the ethylene copolymerized polypropylene is less than 3 mol%, the adhesive strength of the first polymer layer to polyethylene-2,6-naphthalate cannot be sufficiently obtained, so that the longitudinal stretching step of the multilayer film is not possible. May cause peeling, this is cut in the horizontal stretching process,
It may cause a surface defect of the first polymer layer. On the other hand, if the ethylene copolymerization ratio exceeds 20 mol%, the stretchability becomes poor, and it becomes difficult to form a stable film. For this reason, the ethylene copolymerization ratio of the second polymer layer is 3 to 20.
mol%, preferably 4 to 15 mol%, more preferably 7 to
10 mol% is preferred.

Further, ethylene copolymerized polypropylene is
Those having an MFR of 0.5 to 50 g / 10 minutes are preferred. MF
If R is less than 0.5 / 10 minutes, a problem may occur in the flow characteristics of the resin in the die during multilayer extrusion. On the other hand, if the MFR is larger than 50 g / 10 minutes, a defect may occur on the peeled surface of the first polymer layer.

The copolymer structure of the ethylene copolymerized polypropylene is not particularly limited as long as it is an ethylene-propylene copolymer, but a random copolymer and a block copolymer are preferred. In particular, it is preferable to use ethylene random copolymerized polypropylene because the peeling surface characteristics of the first polymer layer are improved.

The ethylene copolymerized polypropylene according to the present invention has a quaternary phosphonium sulfonic acid salt of 0.001 to 0.001.
The content of 1 wt% is preferable because the electrostatic adhesion to the casting drum when casting the multilayer film becomes sufficient.

Further, ethylene copolymerized polypropylene is
Melting point (Tm) of the thermoplastic resin constituting the first polymer layer
The specific volume resistance in the molten state at a temperature higher by 15 ° C. is 0.5 × under the measurement condition of the AC voltage of 50 Hz.
It is preferably 10 ⁹ Ω · cm or less. When the volume resistivity is in this range, the application of electrostatic charge to the multilayer film during casting becomes strong, and the adhesion between the cooling drum and the multilayer film becomes good.

In the present invention, the thermoplastic resin constituting the second polymer layer has an average particle diameter of 0.001 to 0.002 in order to improve the winding property of the second polymer layer film separated and separated from the multilayer stretched film. It is preferable that organic or inorganic fine particles of about 5.0 μm are mixed and contained, for example, at a ratio of 0.01 to 2.0 wt%. Such fine particles include, for example, dry silica, wet silica, zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, titanium oxide, alumina, zirconia, aluminum hydroxide, calcium oxide, zinc oxide,
Examples include inorganic particles such as silicon carbide and silver oxide, and organic particles such as crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles.

Further, the thermoplastic resin constituting the second polymer layer may contain, if necessary, an antioxidant, an antistatic agent, a coloring agent, a pigment, a tendency brightener, a plasticizer, an ultraviolet absorber, and other additives. Resins and the like can be added.

[Multilayer stretched film] The multilayer structure of the multilayer stretched film of the present invention is such that the thickness of the first polymer layer is 1 to 5 μm.
m, and the thickness of the second polymer layer is in the range of 3 to 10 μm. When the thickness of the second polymer layer is less than 3 μm, the first polymer layer is cut off when the first polymer layer is separated from the multilayer stretched film, resulting in poor productivity. On the other hand, when the thickness is more than 10 μm, the raw material cost of the second polymer layer increases, and the production cost increases.

On the other hand, the thickness of the first polymer layer is 1 to 5 μm
However, it is preferably 1.5 to 5 μm, more preferably 1.5 to 3 μm.
μm is preferred. When the thickness is less than 1 μm, when the first polymer layer film obtained by peeling from the multilayer stretched film is used as a base film for a thermal transfer printer ribbon, ribbon cutting frequently occurs, which is not preferable.
If it exceeds 5 μm, the sharpness at the time of high-speed printing by thermal transfer becomes insufficient.

The multilayer film according to the present invention has a structure in which at least one first polymer layer and at least one second polymer layer are adjacent to each other and at least one outermost layer is composed of the first polymer layer. The number of layers is not particularly limited. However, when the film is a multilayer film of three or more layers, the first polymer and the second polymer layer are alternately provided.

A specific example of this layer structure will be described in the case where the first polymer layer is composed of a linear polyester layer (E layer) and the second polymer layer is composed of a polyolefin layer (O layer). Two-layer film consisting of E layer / O layer / E
Three-layer film consisting of layers, E layer / O layer / E layer / O layer / E
Preferable examples include a five-layer film composed of layers. Among them, a three-layer film composed of E layer / O layer / E layer is particularly preferable.

The multilayer film according to the present invention has an interlayer adhesion between the first polymer layer and the second polymer layer of 0.1 to 20 g.
/ Cm, particularly preferably in the range of 0.1 to 10 g / cm. This interlayer adhesion is 0.1 g / c
If it is smaller than m, delamination or delamination occurs when the multilayer film is wound into a roll and stored or transported,
Troubles such as wrinkles and tears may occur, and troubles may occur in which the multilayer film peels off before being subjected to the stretching treatment. On the other hand, if the interlayer adhesive strength is more than 20 g / cm, the interlayer adhesive strength is too strong, so that when the multilayer film is separated, the film is broken or a pinhole is formed, which is not preferable.

In order to adjust the adhesive strength between the first polymer layer and the second polymer layer, a lubricant can be blended into the second polymer layer, if desired. For example, when ethylene copolymerized polypropylene is used for the second polymer layer, the lubricant is used in an amount of, for example, 0.001 to 1 wt%, and more preferably 0.005 to 1 wt%.
0.5 wt% can be blended.

The lubricant may be liquid or solid at room temperature, but preferably has a melting point or softening point of 200 ° C. or less. Specific examples of the lubricant include the following, and two or more of these may be used.

A. Aliphatic hydrocarbons: liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyethylene wax, polypropylene wax, etc. Higher fatty acids or metal salts thereof: stearic acid, calcium stearate, hydroxystearic acid, hydrogenated oil, sodium montanate, etc. Aliphatic amide: stearamide, oleamide, erucamide, ricinoleamide, behenamide, methylenebisstearamide, etc. Fatty acid esters: n-butyl stearate, methylhydroxystearate, myristyl celloate, high alcohol fatty acid esters, ester waxes, etc. Fatty acid ketone: ketone wax, etc. Fatty alcohol: lauryl alcohol, stearyl alcohol, myristyl alcohol, cetyl alcohol, etc. Partial esters of fatty acids and polyhydric alcohols: glycerin fatty acid esters, hydroxystearic acid triglycerides, sorbitan acid esters, etc. Nonionic surfactants: polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene alkyl amide, polyoxyethylene fatty acid ester, etc. Silicon oil: straight-chain methyl silicone oil, methylphenyl silicone oil, modified silicone oil, etc. Fluorinated surfactants: fluoroalkyl carboxylic acid, perfluoroalkyl carboxylic acid, monoperfluoroalkyl ethyl phosphate, perfluoroalkyl sulfonic acid salt, etc.

The multilayer stretched film in the present invention may be either a uniaxially stretched film or a biaxially stretched film.
In particular, a biaxially stretched film is preferable because a single-layer film having excellent biaxial mechanical properties can be obtained.

At the time of film formation, it is preferable to use a filter in order to remove foreign matters in the second polymer layer and reduce fish eyes and the like. At this time, the average aperture of the filter is preferably 35 μm or less, and more preferably 28 μm.
m or less. The material of the filter may be metal or ceramic, but stainless steel is preferable because it can be recycled. The filter may be manufactured in any of a mesh type, a non-woven cloth type, a sintered type, and the like.

[Stretched polyethylene-2,6-naphthalate film] In the present invention, stretched polyethylene-2,6-naphthalate film is used.
6-naphthalate film is polyethylene-2,6-
At least one layer of a first polymer layer made of naphthalate and at least one layer of a second polymer layer made of a thermoplastic resin incompatible with polyethylene-2,6-naphthalate are adjacent to each other, and the layer is indirect between these two layers. Strength is 0.1-2
0 g / cm, at least one of the outermost layers is a first polymer layer, and the second polymer layer and the first polymer layer are alternately present in a multilayer stretched film,
The thickness of the first polymer layer is in the range of 1 to 5 μm, the thickness of the second polymer layer is in the range of 3 to 10 μm, and the resin constituting the first polymer layer has a shear rate at 280 ° C. of 100 sec.
^-1 is a film obtained by peeling the first polymer layer from a multilayer stretched film having a higher viscosity than the melt viscosity of the resin constituting the second polymer layer at a shear rate of 280 ° C. at a shear rate of 100 sec ⁻¹ at 280 ° C. .

The stretched polyethylene-2,6 of the present invention
The naphthalate film has 4 to 20 μm long crater-like defects on the surface peeled from the second polymer layer.
The number is 30 or less per mm square.

This crater-like defect is a transfer of crater-like irregularities present on the surface of the second polymer layer. A typical shape is a circle or an ellipse, and the length of the minor axis is the length of the major axis. It is about one-fifth to one.

This crater-like defect is 30 mm per 4 mm square.
If the number exceeds the number, when a stretched polyethylene-2,6-naphthalate film is used as a base film of a thermal transfer ribbon, print defects become remarkable and the use cannot be tolerated. Since the stretched polyethylene-2,6-naphthalate film is thin, this printing defect occurs when the heat-sensitive ink layer is provided on either the peeled side or the non-peeled side of the film. It is preferable to provide it on the side, since the printing defect becomes small.

A stretched polyethylene-2,6-naphthalate film having a crater-like irregularity having a major axis of 5 to 20 μm and having a length of 30 or less per 4 mm square present on the peeled surface is, for example, polyethylene-2,6-naphthalate in the first polymer layer. Used, a shear rate of 100 sec at 280 ° C. for the second polymer layer.
The melt viscosity at c ^-1 is lower than that of polyethylene-2,6-naphthalate.
It can be obtained by peeling and separating the first polymer layer from a multilayer stretched film obtained using 1% ethylene copolymerized polypropylene.

The lower limit of the number of crater-shaped defects per 4 mm square is 0. For this purpose, in addition to using the polymer having the above melt viscosity, for example, when forming a film,
Using a thermoplastic resin with very few foreign materials in the polymer layer,
It is effective to use a filter having an extremely fine average opening for melt extrusion of the second polymer layer, but the filter is clogged in a short time and needs to be frequently replaced. In some cases, there is a difficulty in economy, for example, the recycled thermoplastic resin is not used. For this reason, the number of crater-shaped defects per 4 mm square is preferably 1 or more, particularly 5 or more.

The number of crater-like defects is polyethylene-
As 2,6-naphthalate, the melt viscosity can be reduced by using one having a sufficiently higher viscosity than the melt viscosity of the thermoplastic resin constituting the second polymer layer. For example, the first polymer layer may have a shear rate of 100 s at 280 ° C.
The melt viscosity at ec ^-1 is 500 Pa · s or more, especially 6
A polyethylene-2,6-naphthalate of at least 00 Pa · s is used, and a shear rate of 100 at 280 ° C.
To obtain a stretched polyethylene-2,6-naphthalate film having a small number of crater-like defects by using a material having a melt viscosity at sec- ¹ of 1/2 or less, particularly 1/3 or less of polyethylene-2,6-naphthalate. Can be.

The stretched polyethylene-2,6 according to the present invention
-The naphthalate film may be either a uniaxially stretched film or a biaxially stretched film, but a biaxially stretched film is particularly preferred because it has excellent mechanical properties in the biaxial direction and is suitable for a base film of a thermal transfer ribbon.

In the stretched polyethylene-2,6-naphthalate film, the number of protrusions at a slice level of 800 nm in the surface protrusion distribution on the surface peeled off from the second polymer layer is smaller than the protrusion count on the surface not peeled off from the second polymer layer. It is preferably at least 80% of the number.

The number of protrusions on the peeled surface is 80% or more of the number of protrusions on the surface not peeled.
The 2,6-naphthalate film has a melt viscosity of polyethylene-2,6-naphthalate of the first polymer layer of the second polymer layer.
It can be obtained by peeling and separating the first polymer layer from a multilayer stretched film obtained using a polymer layer having a higher viscosity than the melt viscosity of ethylene copolymerized polypropylene.

When the number of protrusions is less than 80%, when a stretched polyethylene-2,6-naphthalate film is used as a base film of a thermal transfer ribbon, a back coat (fusion prevention layer) or an ink layer may not be formed. It is not preferable because the coating property and the film take-up property become poor, and the running property of the thermal transfer ribbon also becomes poor.

The stretched polyethylene-2,6-naphthalate film has a Young's modulus in the longitudinal direction of 650 to 1000.
kg / mm ² is preferable, and more preferably 700 to 1000
A range of kg / mm ² is preferred. Young's modulus in vertical direction is 6
If less than 50 kg / mm ² , stretched polyethylene-2,
When the 6-naphthalate film is used as the base film of the thermal transfer ribbon, the Young's modulus is insufficient, so that it cannot withstand head rubbing during thermal transfer printing, causing wrinkles or cutting. Further, a film exceeding 1000 kg / mm ² is difficult to produce because the film-forming conditions are severe and cutting occurs frequently when forming a multilayer stretched film.

In order to obtain a stretched polyethylene-2,6-naphthalate film, a multilayer stretched film using polyethylene-2,6-naphthalate as the first polymer layer is produced. , 6-
Shear rate 100 sec at 280 ° C as naphthalate
^-1, the rigidity of the polyethylene-2,6-naphthalate film in the stretching step is sufficiently increased by selecting a resin having a melt viscosity higher than the melt viscosity of the resin constituting the second polymer layer. The transfer to the polyethylene-2,6-naphthalate film surface is small even when there are fish eyes and large projections, and when used as a base for a thermal transfer ribbon, there is little adverse effect on printability.

The stretched polyethylene-2,6 in the present invention
-The naphthalate film preferably has a dimensional change with respect to the original length of the film up to a temperature of 200 ° C. within 1.0%, particularly preferably 0.1% when a temperature dimensional change curve under a vertical load is measured. The dimensional change under a load relative to the original length of the film up to 230 ° C. is preferably within 3.0%, particularly preferably within 1%.

The temperature dimensional change curve under a load in the vertical and horizontal directions (hereinafter, also referred to as a “TMA curve”) is defined by holding both ends of the film in the vertical or horizontal direction and applying a constant load of a certain value. While the film was heated at a constant heating rate, the temperature was plotted on the horizontal axis, and the dimensional change rate with respect to the original length of the film was plotted on the vertical axis.

The oriented polyethylene-2,6-naphthalate film may contain additives such as stabilizers, dyes, lubricants, ultraviolet absorbers, and flame retardants, if desired.

In particular, it is preferable to contain a small amount of inert particles in order to impart favorable lubricity to the film. Such inert particles include, for example, spherical silica,
Porous silica, calcium carbonate, silica alumina, alumina, titanium dioxide, kaolin clay, barium sulfate,
Examples thereof include inorganic particles such as zeolite, or organic particles such as silicon resin particles and crosslinked polystyrene particles. The inorganic particles are preferably synthetic products rather than natural products for reasons such as uniform particle size, and inorganic particles of any crystal form, hardness, specific gravity, and color can be used.

The inert particles have an average particle size of 0.05 to
It is preferably in the range of 5.0 μm, and 0.1 to 3.0 μm.
More preferably, it is 0 μm. Further, the content of the inert particles is preferably from 0.001 to 1.0% by weight, and more preferably from 0.03 to 0.5% by weight. The inert particles to be added to the film may be a single component selected from those exemplified above, or a multi-component containing two or more components. The addition time of the inert particles is not particularly limited as long as it is a stage until the multilayer stretched film is formed. For example, the inert particles may be added at the polymerization stage of polyethylene-2,6-naphthalate. It may be added.

By adding a lubricant in this way, a stretched polyethylene-2,6-naphthalate film having an average surface roughness of 0.01 to 0.2 μm can be obtained. When the average surface roughness of the film is smaller than 0.01 μm, sufficient slip properties cannot be obtained, and it becomes difficult to wind the film. On the other hand, if the average surface roughness is larger than 0.2 μm, the heat transfer becomes poor when printing at high speed with a thermal transfer printer, and the printing becomes unclear. If the particle size of the inorganic or organic lubricant to be added is smaller than 0.05 μm, a sufficiently large surface roughness cannot be obtained, and the winding property is reduced, and the productivity is reduced. When it is larger than 5.0 μm, the film is likely to be broken in the stretching step.

[Easy-Adhesive Layer] An easily-adhesive layer can be provided on at least one surface of the multilayer stretched film of the present invention to improve the adhesion to the heat-sensitive ink layer and the like.

In particular, when a stretched polyethylene-2,6-naphthalate film is used as a base film for a thermal transfer ribbon, the film easily adheres to the outer surface of the stretched polyethylene-2,6-naphthalate film which is the outermost layer of the multilayer stretched film. It is preferable to provide a heat-sensitive transfer layer, because the adhesion between the heat-sensitive transfer ink layer or the anti-fusing layer and the base film becomes strong.

The easily adhesive layer is a coating layer made of at least one aqueous resin (a water-soluble or water-dispersible resin) selected from the group consisting of a urethane resin, a polyester resin, an acrylic resin and a vinyl resin-modified polyester resin. Preferably, there is.

The urethane resin constituting the easily adhesive layer includes, as components constituting the urethane resin, the following polyvalent hydroxy compounds, polyvalent isocyanate compounds, chain extenders,
Crosslinking agents and the like can be exemplified. That is, as the polyvalent hydroxy compound, polyoxyethylene glycol, polyoxypropylene glycol, polyethers such as polyoxytetramethylene glycol, polyethylene adipate, polyethylene-butylene adipate, polyesters such as polycaprolactone, polycarbonates, Acrylic polyols, castor oil and the like can be used. As polyvalent isocyanate compounds, tolylene diisocyanate, phenylene diisocyanate,
4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like can be used. Examples of the chain extender or the crosslinking agent include ethylene glycol, propylene glycol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, ethylenediamine-sodium acrylate adduct, 4,4′-diaminodiphenylmethane, and 4,4′- Diaminodicyclohexylmethane, water and the like can be used. One or more of these compounds are appropriately selected, and a urethane resin is synthesized by a conventional polycondensation-crosslinking reaction.

The following polyvalent carboxylic acids and polyvalent hydroxy compounds can be exemplified as constituents of the polyester resin constituting the easily adhesive layer. That is, as the polycarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5
-Naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid , Succinic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, monopotassium trimellitic acid and their ester-forming derivatives and the like can be used, and polyhydric hydroxy compounds can be used. Are ethylene glycol, 1,2-propylene glycol, 1,3
-Propylene glycol, 1,4-butanediol,
1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol,
Bisphenol A-ethylene glycol adduct, bisphenol A-1,2-propylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin,
Trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate and the like can be used. One or more of these compounds are appropriately selected, and a polyester resin is synthesized by a conventional polycondensation reaction. In addition to the above, a composite polymer having a polyester component such as a polyester polyurethane obtained by chain-extending a polyester polyol with an isocyanate is also included in the polyester resin referred to in the present invention.

The acrylic resin constituting the easy-adhesive layer preferably contains alkyl acrylate or alkyl methacrylate as a main component, and the component is preferably 30 to 9%.
It is a water-soluble or water-dispersible resin containing 0 to 10 mol% of a copolymerizable vinyl monomer component having a functional group. Vinyl monomers having a functional group copolymerizable with an alkyl acrylate or an alkyl methacrylate have a carboxyl group or a salt thereof, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylol group as a functional group. It is a vinyl monomer having an amide group, an amino group (including a substituted amino group) or an alkylolated amino group or a salt thereof, a hydroxyl group, an epoxy group and the like. Of these, particularly preferred are a carboxyl group or a salt thereof, an acid anhydride group, and an epoxy group. Two or more of these groups may be contained in the resin. Examples of the alkyl group of the alkyl acrylate and the alkyl methacrylate include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-
Examples thereof include a butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, a lauryl group, a stearyl group, and a cyclohexyl group.

As the vinyl monomer having a functional group copolymerizable with an alkyl acrylate or an alkyl methacrylate, the following compounds having a functional group such as a reactive functional group, a self-crosslinkable functional group, and a hydrophilic group can be used. . Examples of the compound having a carboxyl group or a salt thereof, and an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, metal salts of these carboxylic acids with sodium, ammonium salts, maleic anhydride, and the like. . Examples of the compound having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, metal salts of these sulfonic acids with sodium and the like, and ammonium salts. Examples of the compound having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide, methylolated methacrylamide, ureido vinyl ether, β-ureido isobutyl vinyl ether, ureido ethyl acrylate, and the like. No. Examples of the compound having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, and dimethylaminoethyl. Vinyl ethers, those whose amino groups are methylolated,
Examples thereof include those quaternized with an alkyl halide, dimethyl sulfate, sultone, or the like. As the compound having a hydroxyl group, β-hydroxyethyl acrylate, β
-Hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxyethyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, Examples of the compound having an epoxy group, such as polypropylene glycol monomethacrylate, include glycidyl acrylate and glycidyl methacrylate. Other compounds having a functional group include vinyl isocyanate and allyl isocyanate.
Further, olefins such as ethylene, propylene, methylpentene, butadiene, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, vinyl trialkoxysilane, acrylonitrile,
Methacrylonitrile, vinylidene chloride, vinyl chloride, vinylidene fluoride, ethylene tetrafluoride, vinyl acetate, and the like are also examples of the vinyl monomer compound.

The vinyl resin-modified polyester resin constituting the easily adhesive layer can be synthesized by polymerizing the vinyl resin in an aqueous solution or aqueous dispersion of a water-soluble or water-dispersible polyester resin. Examples of the components constituting the vinyl-based resin-modified polypolyester include the following polybasic acids or their ester-forming derivatives and polyols or their ester-forming derivatives. That is, polybasic acid components include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, and pyromellitic acid And dimer acid. A copolymerized polyester resin is synthesized using two or more of these acid components. Also, it is possible to use a small amount of an unsaturated polybasic acid component such as maleic acid, itaconic acid and the like, and hydroxycarboxylic acids such as p-hydroxybenzoic acid and the like. As the polyol component, ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylene glycol, dimethylolpropane, poly (ethylene oxide) glycol, And poly (tetramethylene oxide) glycol. Two or more of these can be used. Further, vinyl-based monomers such as those exemplified below are exemplified. Examples of the vinyl monomer include alkyl acrylates and alkyl methacrylates (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, Cyclohexyl group); 2
Hydroxy-containing monomers such as -hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate; acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N, N-dialkylacrylamide , N,
N-dialkyl methacrylate (as the alkyl group,
Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-
Ethylhexyl group, cyclohexyl group, etc.), N-alkoxyacrylamide, N-alkoxymethacrylamide, N, N-dialkoxyacrylamide, N, N-dialkoxymethacrylamide (as the alkoxy group,
Methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylolacrylamide, N-methylolmethacrylamide, N-phenylacrylamide, N-
Amide group-containing monomers such as phenylmethacrylamide;
Glycidyl acrylate, glycidyl methacrylate,
Epoxy group-containing monomers such as allyl glycidyl ether; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.) ) Or a monomer containing a galoxy group or a salt thereof; a monomer of an acid anhydride such as maleic anhydride or itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, vinyl Trialkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, alkyl itaconic acid monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, pig Monomers such as ene. In addition, these monomers are exemplified, but not limited thereto. These monomers may be used alone or in combination.
Copolymerization can be carried out using more than one species.

The aqueous coating liquid used for coating the easily adhesive layer on the surface of the multilayer film may contain a small amount of an organic solvent as long as it does not affect the aqueous resin and other additives.

The aqueous coating solution can be used by adding a necessary amount of a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant. As such a surfactant, the surface tension of the aqueous coating solution is 40 dyn.
e / cm or less, which promotes wetting to the polyester film. For example, polyoxyethylene alkylphenyl ether, polyoxyethylene-fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate , Alkyl sulfonates, alkyl sulfosuccinates, quaternary
Grade ammonium chloride salt, alkylamine hydrochloride, betaine type surfactant and the like.

In the easily adhesive layer of the present invention, an isocyanate-based compound, an epoxy-based compound, an oxazoline-based compound, and the like are used as crosslinking agents in order to improve fixation (blocking properties), water resistance, solvent resistance, and mechanical strength. It may contain an aziridine compound, a melamine compound, a silane coupling agent, a titanium coupling agent, a zirco-aluminate coupling agent, or the like. If the resin component of the easily adhesive layer has a crosslinking reaction point, a reaction initiator such as a peroxide or an amine, or a sensitizer may be contained in a photosensitive resin or the like.
In order to improve the sticking property and the sliding property, silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, calcium phosphate, titanium oxide, barium sulfate, carbon black are used as inorganic fine particles in the easily adhesive layer. , Molybdenum sulfide, antimony oxide sol, etc., as organic fine particles, polystyrene,
It may contain polyethylene, polyamide, polyester, polyacrylate, epoxy resin, silicone resin, fluorine resin and the like. Further, if necessary, an antifoaming agent, a coating improver, a thickener, an antistatic agent, an organic lubricant, an antioxidant, a foaming agent, a dye, a pigment and the like may be contained.

The easily adhesive layer according to the present invention comprises the urethane resin, polyester resin, acrylic resin and vinyl resin-modified polyester resin on one or both sides of the multilayer film before the crystal orientation of the first polymer layer is completed. It can be obtained by applying an aqueous coating liquid containing at least one selected from the group, drying, stretching, and further performing a heat treatment.

The application of the aqueous coating solution may be carried out separately from the production process of the multilayer film. However, in this case, dust and dirt are easily entrained, and the portion becomes a defect at the time of printing. desirable. Coating during the manufacturing process of the multilayer film is particularly preferable because a suitable film can be manufactured at relatively low cost. At that time, the solid content concentration of the coating solution is usually 0.1 to 30% by weight, more preferably 1 to 10% by weight.
% By weight. The coating amount is preferably 0.5 to 50 g per 1 m ^{2 of the} running film.

[Fusing prevention layer] Stretched polyethylene-2,6
-When a naphthalate film is used as the base film for a thermal transfer ribbon, it is preferable to provide a fusion prevention layer for preventing sticking of the thermal head on the surface opposite to the surface on which the thermal transfer ink layer is laminated.

As the anti-fusion layer, a silicone resin, an acrylate or a methacrylate having a crosslinkable functional group, or a polyester copolymer thereof is an isocyanate,
Epoxy, crosslinked with melamine, fluorine resin,
It is preferably made of silicone oil, mineral oil or the like.

The fusion preventing layer is made of stretched polyethylene-2,6
After the naphthalate film is separated from the stretched multi-layer film, it can be coated (off-line coating) by applying a coating solution containing the above components to the surface, but a multilayer stretched film is formed. In the process, it can be applied to the outer surface of the polyethylene-2,6-naphthalate film. When the anti-fusing layer is applied in the process of forming the multilayer stretched film, a coating solution containing the above components is applied to the outer surface of the multilayer film before the completion of the crystal orientation, and then dried, stretched, and further heat-treated. Can be obtained. By doing so, the heat history at the time of processing into a transfer ribbon can be reduced, and a film with less wrinkles can be obtained.

A known method can be applied as a coating method. For example, roll coating, gravure coating, roll brushing, spray coating, air knife,
An impregnation method, a curtain coating method, or the like may be applied alone or in combination.

[Production of Multilayer Stretched Film] In the production of the multilayer stretched film in the present invention, first, a thermoplastic resin forming the first polymer layer, for example, a linear polyester, and a thermoplastic resin forming the second polymer layer adjacent thereto are formed. A multilayer molten sheet of a resin, for example, an ethylene copolymerized polypropylene, particularly a random copolymerized polypropylene, is co-extruded onto a rotary cooling drum, brought into close contact with the rotary cooling drum, and cooled to form an unstretched multilayer sheet.

At this time, preferably, one or both of the polymers constituting the first polymer layer and the second polymer layer are
0.001 to 1 wt% of quaternary phosphonium sulfonate
%, And an electrostatic charge is applied to the molten surface of the sheet in a non-contact manner in the vicinity where the multilayered molten sheet reaches the rotating cooling drum.

For example, the ethylene copolymerized polypropylene and the linear polyester are supplied to separate extruders and melted at a temperature not lower than the melting point of each polymer and up to 350 ° C., preferably at the same temperature. A non-stretched multilayer sheet is produced by merging inside a die (die) to form a multilayer state, discharging this from the die, applying an electrostatic charge to the discharge sheet, and cooling and solidifying while closely adhering to the cooling drum. Can be.

The unstretched multilayer sheet may have any number of layers as long as the multilayer sheet has two or more adjacent first and second polymer layers.

The raw material of the thermoplastic resin is preferably dried before being supplied to the extruder. For example, when the thermoplastic resin constituting the first polymer layer is a linear polyester, 1
Those dried at a temperature of from 00 ° C to 200 ° C can also be used. Of course, when the thermoplastic resin constituting the second polymer layer is ethylene copolymerized polypropylene, it is not necessary to dry this material, but it is also possible to use a material dried at a temperature of 100 ° C. or more and less than Tm (melting point). it can.

The multilayer stretched film of the present invention is preferably heat-set after stretching. In particular, when a linear polyester is used for the first polymer layer, it is preferable to heat-set the multilayer film after biaxial stretching. In this case, the heat setting treatment is preferably performed by the following method. That is, the heat fixing zone (X1, X2,...) Divided into two or more sections
The temperature of the first zone (X1) is set to (TSD + 40) ° C. or more with respect to the stretching temperature (TSD, ° C.).
D + 100) ° C. or lower, and further, in the heat setting zones after the first zone, zones having a temperature higher than the temperature of the first zone are provided, and the film is set in the heat fixing zones by 4 hours.
Heat set while extending ~ 35%. At this time, the temperature of the highest temperature heat fixing zone is 225 ° C. or more, preferably 235 ° C.
The temperature is preferably in the range of not less than 250 ° C. and not more than the zone where the maximum temperature is reached, and it is preferable that the relaxation treatment and the tension treatment are not performed.

The first polymer layer has polyethylene-2,6-
In the case of using naphthalate, particularly preferable production conditions are described below. That is, polyethylene-2,6-naphthalate and ethylene copolymerized polypropylene are supplied to separate extruders, and are melted at a temperature not lower than the melting point of each polymer and up to 350 ° C., preferably at the same temperature. Alternatively, an unstretched multilayer sheet is manufactured by merging inside a molding die (die) to form a multilayer state, discharging the film from the die, applying an electrostatic charge to the discharge film, and cooling and solidifying the film while closely contacting the cooling drum. I do.

The obtained unstretched multilayer sheet was subjected to a glass transition temperature (Tg, ° C.) of polyethylene-2,6-naphthalate.
(Tg + 50) C. or less in the vertical direction at a temperature of not more than
6.0 times, preferably 4.1 to 5.5 times, more preferably 4.6 to 5.2 times, 2.1 to 4.5 times in the horizontal direction, preferably 2.8 to 4.0 times. After stretching biaxially at a stretching ratio of, a heat setting zone (X1,
In the first zone (X1) in (X2,...), A temperature of (lateral stretching temperature + 40) ° C. to (lateral stretching temperature + 100) ° C., preferably (lateral stretching temperature + 45) ° C. to (lateral stretching temperature + 100) ° C. The heat setting is performed at the temperature for 1 to 50 seconds, and the heat setting is continued in the remaining heat setting section. At this time, the film is heat-set while the film is stretched so that the width of the exit of the final section becomes wider by 4 to 35% as compared with the width of the entrance of the first section (X1) of the heat-setting zone. At this time, the film may be stretched only in the first one zone, or may be stretched in two or more continuous zones or intermittently.

When the relaxation treatment is carried out, it is preferable to carry out the treatment in a zone before the maximum heat setting temperature. However, the relaxation treatment method is to reduce the tenter width in the middle of the heat fixing zone and to reduce the width by -5 to 5% in the film width direction. Is preferred.

From the stretched (biaxially stretched) multilayer film obtained under such production conditions, the polyethylene-2,6-naphthalate layer was separated and separated, and further slit into a predetermined width.
A stretched (biaxially oriented) polyethylene-2,6-naphthalate film can be obtained.

The biaxially oriented polyethylene-2,6-naphthalate film thus obtained is provided with the above-mentioned thermal transfer ink layer and the anti-fusing layer and slit to a predetermined width to produce a thermal transfer ribbon. can do.

The stretched multilayer film has, for example,
JP-B-56-183815 and JP-B-57-30854
A surface activation treatment (for example, a plasma treatment, an amine treatment, a corona treatment, or the like) as known in Japanese Patent Application Laid-Open (Kokai) No. 2000-216, etc. may be performed.

The multilayer stretched film of the present invention may be used as it is, or a single-layer stretched film obtained by peeling and separating the first polymer layer or the second polymer layer may be used for various purposes. good. For example, when an ultra-thin polyester film having a thickness of 3 μm or less is manufactured as a single layer,
There is a disadvantage that the production yield is extremely low because breakage or poor winding in the stretching process is likely to occur, but if the multilayer stretched film of the present invention is separated into a single-layer stretched film,
An ultra-thin film can be easily obtained. In addition, the ultrathin film is not easy to handle even on the handling surface, but in the multilayer stretched film of the present invention, in the processing step that requires handling, it is handled as a multilayer stretched film, and after handling, the handling is improved by separating. Can be.

The polyester single-layer stretched film obtained by peeling from the multilayer stretched film of the present invention is required to be extremely thin and have a high Young's modulus for capacitors, magnetic recording, etc., in addition to the base film of a ribbon for a thermal transfer printer. It is useful for the used application.

Further, the multilayer film has a sandwich structure such as E layer (linear polyester layer) / O layer (polyolefin layer) / E layer. By peeling and separating, it is possible to obtain an ultra-clean O layer (polyolefin single-layer film) with a very small amount of oxide film on the surface and little adhesion of foreign matter on the surface. Further, the multilayer stretched film has a sandwich structure of five layers such as E layer / O layer / E layer / O layer / E layer, and the E layer of the intermediate layer is separated and separated.
An ultra-clean (E-layer) linear polyester single-layer film having an extremely small amount of an oxide film on the surface and little foreign matter adhering to the surface can be obtained. Further, by peeling and separating each layer from the stretched multilayer film of the present invention, two or more biaxially stretched single-layer films can be obtained simultaneously in two or more sheets, and high efficiency and low cost can be obtained. .

[0093]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value was measured by the following method.

1. Melt Flow Mate (MFR) The weight of the polymer extruded for 10 minutes is measured by using an MFR measuring device manufactured by Takara Kogyo Co., Ltd., heated at 260 ° C., using a nozzle having a diameter of 1 mm and a length of 10 mm, and is defined as MFR. (J
IS K6758)

2. Film thickness The film thickness is measured by a gravimetric method for a film peeled and separated from the multilayer stretched film.

3. Interlayer Adhesive Force The film width is 10 mm, the chuck interval is 100 mm, and the tension (g) applied when the first polymer layer is peeled from the second polymer layer at a peel angle of 180 degrees at a speed of 2 m / min is measured. The average value of the tension and the tension per 1 cm of the width obtained from the sample width (10 mm) were calculated as the interlayer adhesion force: T (g /
cm).

4. Melt viscosity Nozzle diameter 1mm using Shimadzu flow tester
The melt viscosity is defined as the apparent viscosity at a shear rate of 100 SEC ^-1 measured after holding at 280 ° C. for 5 minutes using a die.

5. Melting point The temperature corresponding to the top of the endothermic peak accompanying melting when a sample (10 mg) was heated at a heating rate of 20 ° C./min using DSC (V4.OB2000 model manufactured by DuPont). Determine the melting point.

6. Glass transition temperature The sample (10 mg) was heated at a heating rate of 20 ° C./min using a DSC (V4.OB2000 type device manufactured by DuPont) to measure the glass transition temperature.

7. Vertical Young's modulus The film peeled from the multilayer stretched film is cut into a sample width (horizontal direction) of 10 mm and a length (vertical direction) of 150 mm.
100mm between chucks, pulling speed 10mm / mi
n, the sample is pulled with an Instron type universal tensile tester under the conditions of a chart speed of 500 m / min. Then, the Young's modulus (longitudinal Young's modulus) is calculated from the tangent to the rising portion of the obtained weight-elongation curve.

8. Surface property (peeling rate of peeling surface protrusion) The peeling surface and non-peeling surface of the first polymer layer film peeled from the multilayer film are measured at a cutoff of 0.25 mm using a non-contact surface roughness meter HYPOS manufactured by Kosaka Laboratory. 100 scans of 1 mm in length are made at a pitch of 2 μm, and the number of protrusions at a slice level of 800 nm is measured. The ratio (%) of the number of protrusions on the peeled surface to the number of protrusions on the non-peeled surface is defined as the percentage of peeled surface protrusions.

9. Number of transfer surface transfer defects (number of crater-shaped defects) A 4 mm x 4 mm frame was drawn on the release surface of the first polymer layer film peeled from the multilayer stretched film, and the inside of the frame was observed with an optical microscope, and the major axis was 5 to 20 m. Are counted at n = 3, and the average value is defined as the number of transfer surface transfer defects.

10. Temperature Dimension Change Curve (TMA Curve) A longitudinal TMA curve of the first polymer layer film peeled from the multilayer stretched film is measured using TMA / SS120C manufactured by Seiko Instruments Inc. However, the measurement conditions were as follows: the sample was 15 mm in length (longitudinal direction) and 4 mm in width (horizontal direction). Using a quartz holder, the measurement temperature range was 0 to 280 ° C., the temperature rising rate was 5 ° C./min, and the load was Is 5 g.

11. Printability (Printer print evaluation) A thermal transfer ribbon is prepared using the first polymer layer film peeled from the multilayer stretched film as a base film, and the image receiving sheet VY 200 (standard paper product manufactured by Hitachi, Ltd.) is used by using this ribbon. Is printed so as to have the maximum optical density using a printer Hitachi VY-200 (trade name, manufactured by Hitachi, Ltd.). With respect to the produced thermal transfer ribbon, printability and wrinkles generated on the ribbon are evaluated according to the following criteria. ：: The image is printed clearly. Δ: Printing density is not uniform. X: The ribbon is wrinkled and the print is disturbed.

12. Coating property of anti-fusing layer (coatability of back coat) After coating the anti-fusing layer, the coated surface is observed and evaluated according to the following criteria. ：: Level applied without unevenness even when seeing through the web △: Level where unevenness is seen when looking through the web ×: Level where application missing occurs in some places

13. Process peelability The state of occurrence of delamination at the time of forming a multilayer film is evaluated based on the following criteria. ◎: Level at which no peeling occurs in the longitudinal stretching step during film formation. ○: Peeling occurs in the vertical stretching step at startup, but peeling is eliminated by nipping the peeled part. △: Peeling occurs in the longitudinal stretching step. ×, level at which horizontal stretching is possible ×: level at which horizontal stretching is impossible due to peeling in longitudinal stretching

14. Process cutting property The state of occurrence of film cutting during multilayer film formation is evaluated based on the following criteria. ：: Level not cut for 24 hours or more. ：: The level of cutting once on average during 24 hours. Δ: The level of cutting once on average in 16 hours. X: A level of cutting once or more on average in 8 hours.

15. Wound appearance The multilayer film is wound with a roll width of 1 m, and the measurement result of ASKA hardness is evaluated according to the following criteria. ◎: The level of variation in ASKA hardness within 2 degrees over the entire width of 1 m roll. ○: The level of variation in ASKA hardness within 3 degrees over the entire width of 1 m roll. Δ: The level of variation in ASKA hardness within 4 degrees over the entire width of the 1-m roll. X: The level of variation in ASKA hardness of 4 degrees or more over the entire width of the 1-m roll.

16. Breakability at the time of peeling The state of breakage of the film when each layer is wound into a roll while separating and separating the first polymer layer and the second polymer layer from the multilayer film wound up with a 1 m roll width is based on the following criteria. To evaluate. A: A level at which the first polymer layer and the second polymer layer are not broken at all. ：: Breakage of the first polymer layer and the second polymer layer was 300
A level that occurs once every 000 m. Δ: Breakage of first polymer layer and second polymer layer was 100
A level that occurs once every 000 m. ×: Breakage of the first polymer layer and the second polymer layer was 100
A level that occurs once every 00m.

Examples and comparative examples are shown below.

Example 1 To a mixture of 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylate and 60 parts of ethylene glycol, 0.03 part of manganese acetate tetrahydrate was added.
The transesterification reaction was performed while gradually raising the temperature from 50 ° C to 240 ° C. On the way, when the reaction temperature reached 170 ° C., 0.024 parts of antimony trioxide was added, and 0.4 parts by weight of spherical silica particles having an average particle diameter of 1.2 μm were added, and then the temperature reached 220 ° C. At this time, a mixture of 0.042 parts (corresponding to 2 mmol%) of 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt and 0.124 parts of ethylene glycol was added as a solution heated to 40 ° C. Subsequently, a transesterification reaction is carried out, and after the transesterification reaction is completed, trimethyl phosphate is dissolved in ethylene glycol at 135 ° C for 5 hours at 1.1 to 1.6 kg / c.
A solution heat-treated under a pressure of m ² (0.023 parts in terms of trimethyl phosphate) was added. Thereafter, the reaction product was transferred to a polymerization reactor, and the temperature was raised to 290 ° C.
g at a high vacuum of 35 ° C.
0.62 g of intrinsic viscosity measured in chlorophenol
/ Dl and a melt viscosity of 820 Pa · s at 280 ° C and a shear rate of 100 sec ^-1 to obtain pellets of polyethylene-2,6-naphthalate polymer. This pellet is
After drying at 60 ° C. for 5 hours, the mixture was supplied to an extruder for the first polymer layer and melt-extruded at 280 ° C.

On the other hand, ethylene-propylene random copolymerized polypropylene (3,5-
0.05% by weight of tetra-n-butylphosphonium dicarboxybenzenesulfonate, melting point 137 ° C, MF
R12 g / 10 min., Pellets having a melt viscosity of 250 Pa · s at 280 ° C. and a shear rate of 100 sec ⁻¹
After drying for an hour, feed the extruder for the second polymer layer,
It was melt extruded at 280 ° C.

Next, the melt-extruded polymers described above are combined in a die, and polyethylene-2,6-naphthalate / ethylene copolymerized polypropylene / polyethylene-
After forming a three-layer multilayer structure of 2,6-naphthalate, a three-layer molten sheet was discharged from a die. This molten sheet is
It was brought into close contact with a water-cooled casting drum (cooling drum) rotating at a peripheral speed of 7.5 m / min and solidified by cooling to obtain a three-layer unstretched sheet. This unstretched sheet was stretched 4.5 times at 144 ° C. with a high-speed roll at 150 m / min in the longitudinal direction (machine axis direction) by roll stretching to obtain a longitudinally stretched multilayer film.

Next, a coating composition having the following composition 1 was applied to both sides of this longitudinally stretched multilayer film as an easily adhesive layer using a gravure coater so that the coating thickness after drying was 0.1 μm.

Thereafter, the first heat-fixing zone was subjected to a biaxial stretching in the transverse direction (width direction) at 140 ° C. by 3.2 times successively to make the first heat-setting zone 180 ° C.
In the second heat-setting zone, the outlet width is increased to 240 ° C. and at 180 ° C., respectively, so that the inlet width and the outlet width are kept the same. By operating continuously for a time, a biaxially stretched multilayer film having an easily adhesive layer coated on both sides of the layer constitution, layer thickness and interlayer adhesive force shown in Table 1 was obtained. Further, continuous operation was performed for 24 hours under the same conditions except that the application of the easy-adhesion layer was stopped to obtain a biaxially stretched multilayer film having no easy-adhesion layer applied.

The biaxially stretched multilayer film was extremely good in film-forming properties without delamination or cutting of the film after 48 hours of continuous film formation.

<Composition 1 of coating agent> The acrylic resin was 65 mol% of methyl methacrylate / 28 mol% of ethyl acrylate.
/ 2-hydroxyethyl methacrylate 2 mol% / N-
It is composed of 5 mol% of methylol acrylamide, 42 wt% in terms of solid content, and the polyester resin is composed of 35 mol% of terephthalic acid / 13 mol% of isophthalic acid as an acid component.
5-sodium sulfoisophthalic acid 2 mol%, ethylene glycol 45 mol% / diethylene glycol 5 mol% as a glycol component, 42 wt% in terms of solid content, N, N, N ', N'- as an epoxy crosslinking agent The content of tetraglycidyl-m-xylylenediamine is 6% by weight of solid content, and the content of lauryl polyoxyethylene as a wetting agent is 10% by weight of solid content.

Each layer was peeled off and separated from the biaxially stretched multilayer film coated on both sides with the easily adhesive layer obtained by carrying out the above, and the film constituting each layer was wound into a roll with a width of 1 m. I took it. At this time, the separation winding property is such that the peel strength between the layers is 0.9 g / cm, and the layer can be peeled off without any problem. It was good. The unevenness in the vertical thickness of the first layer was 0.3 μm, which was good.

Film thickness, melt viscosity, longitudinal Young's modulus, TMA curve, peeling of the first polymer layer (polyethylene-2,6-naphthalate film having an easily adhesive layer coated on one side) obtained by separation The evaluation result of the number of surface transfer defects
It was good as shown in Table 1. In addition, the surface roughness (peeling surface projection ratio) of the polyethylene-2,6-naphthalate single-layer film obtained by separating the first polymer layer from the biaxially stretched multilayer film not provided with the easy-adhesive layer was measured. Table 1 shows the results.

Next, the polyethylene-2,6-naphthalate film coated with the above-mentioned easy-adhesion layer was coated on the non-adhesion-layer-uncoated surface (peeled surface) with the following composition 2 as an anti-fusing layer. A gravure coater is applied with a thermal transfer ink of the following composition 3 on the surface of the easily adhesive layer so that the coating thickness after drying the agent is 0.5 μm and the coating thickness after drying is 1.0 μm. , And slit to a predetermined width to produce a thermal transfer ribbon.

<Coating composition 2 (anti-fusing layer)> Acrylic ester 14.0% by weight Amino-modified silicone 5.9% by weight Isocyanate 0.1% by weight Water 80.0% by weight <Coating composition 3 (Thermal transfer ink layer)> Magenta dye (MSRedG) 3.5% by weight Polyvinyl acetoacetal resin 3.5% by weight Methyl ethyl ketone 46.5% by weight Toluene 46.5% by weight

The adhesiveness and printability of the ink were evaluated for the produced thermal transfer ribbon. Table 1 shows the evaluation results.

The longitudinal Young's modulus of the first polymer layer is 75%.
It was 0 kg / mm ² , and as a result of evaluating printability and wrinkles at the time of printing occurring on the ribbon, it was good as shown in Table 1. The number of projections at a height of 800 nm of the peeled surface was 90% of the number of projections of the non-peeled surface, and the peelability of the release film and the base film for a thermal transfer printer ribbon was good.

[Examples 2 to 9] The film forming conditions were changed as shown in Table 1, and in Example 4, the longitudinal stretching ratio was 4.0 times.
In Example 5, a biaxially stretched multilayer film was obtained in the same manner as in Example 1 except that the longitudinal stretching ratio was 5.5 times. Next, each layer was separated and separated from the multilayer film, and the film constituting each layer was wound into a roll with a width of 1 m. Further, a thermal transfer ribbon was produced using the first polymer layer film in the same manner as in Example 1. As a result, the film-forming property and the separation-winding property were extremely good, and the first polymer layer film obtained by peeling had extremely good properties as a base film for a thermal transfer ribbon.

[0125]

[Table 1]

Examples 10 to 13 and Comparative Examples 1 to 5
The film forming conditions were changed as shown in Table 2. In Example 12, the longitudinal stretching ratio was 3.5 times, and in Example 13, the longitudinal stretching ratio was 6.0 times, and the transverse stretching ratio was 3.2 times. Except for the above, a biaxially stretched multilayer film was obtained in the same manner as in Example 1. Next, each layer was separated and separated from the multilayer film, and the film constituting each layer was wound into a roll with a width of 1 m. Furthermore,
A thermal transfer ribbon was produced using the first polymer layer film in the same manner as in Example 1. As a result, in Examples 10 to 13, the film formability and the separation and winding property were good, and the first polymer layer film obtained by peeling had good properties as a base film for a thermal transfer ribbon. , Comparative Examples 1 to 5
The film (1) suffers from various obstacles, and it is extremely difficult to form a film and peel off or separate, or it is impossible to use the first polymer layer film obtained by peeling as a base film for a thermal transfer ribbon. Was.

[0127]

[Table 2]

[0128]

According to the present invention, the melt viscosity of the resin of the product layer in the multilayer film is made higher than the melt viscosity of the resin constituting the layer corresponding to the support, and the ethylene copolymerization ratio is selected. The unstretched film does not peel off in the longitudinal stretching step, stretchability, thickness unevenness is good, stable film formation is possible, vertical Young's modulus is high, surface defects are few, and the peeled surface and non-peeled surface Polyethylene-2,6-dicarboxylate for a thermal transfer ribbon having a small difference in surface properties, good printability, and good blocking on the front and back sides can be obtained with high productivity.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B41M 5/40 B29C 55/12 5/38 C08J 5/18 CFD // B29C 55/12 B41M 5/26 B C08J 5/18 CFD 101A B29K 23:00 35:00 67:00 75:00 B29L 9:00 C08L 67:00 F term (reference) 2H111 AA01 AA26 AA27 BB02 BB05 BB06 BB08 4F071 AA12X AA22X AA33X AA34X AA43 AA61 AF62Y AH16 BA01 BB08 BC01 BC10 BC12 BC13 BC14 4F100 AK01A AK01B AK25C AK41A AK41C AK51C AK64B BA02 BA03 BA05 BA06 BA07 BA10A BA10C BA25A BA25B BA31A BA31B DD07B EH46C EJ373 GB41 GB90 JA06A JA06B JB05C JB16A JB16B JK06 JK07B JK14B JL04B JL11A JL11B JL11C YY00 YY00A YY00B 4F210 AA04 AA11 AA20 AA26 AD05 AD08 AG01 AG03 AH33 AH38 QA03 QC06 QD21 QG01 QG15 QG18 QW07

Claims (8)

[Claims] At least one layer of a first polymer layer made of a thermoplastic resin and at least one layer of a second polymer layer made of a thermoplastic resin incompatible with the polymer layer are adjacent to each other. Has an interlayer adhesion of 0.1 to 20 g / c
m, at least one of the outermost layers is a first polymer layer, and the second polymer layer and the first polymer layer are present alternately in a multilayer stretched film, wherein the thickness of the first polymer layer is The range of 1 to 5 μm, the thickness of the second polymer layer is 3 to 10 μm, and the melt viscosity of the resin constituting the first polymer layer at a shear rate of 100 sec ⁻¹ at 280 ° C. constitutes the second polymer layer. 280 ° C of resin
A multi-layer stretched film having a higher viscosity than the melt viscosity at a shear rate of 100 sec ^-1 . 2. The resin constituting the first polymer layer is polyethylene-2,6-naphthalate, and the resin constituting the second polymer layer has an ethylene copolymerization ratio of 3 to 20 mol.
The multilayer stretched film according to claim 1, which is an ethylene copolymerized polypropylene having a MFR of 0.5 to 50 g / 10 minutes. 3. A polyethylene obtained by peeling a first polymer layer from the multilayer stretched film according to claim 1.
A 2,6-naphthalate film, having a major axis of 5 to 20 μm present on the release surface of the film from the second polymer layer;
m is a stretched polyethylene-2,6-naphthalate film having 1 to 30 crater-shaped defects per 4 mm square. 4. A polyethylene-2,6-naphthalate film obtained by peeling the outermost first polymer layer from the multilayer stretched film according to claim 1 or 2, wherein the polyethylene-2,6-naphthalate film is formed from the second polymer layer of the film. The number of protrusions at a slice level of 800 nm in the distribution of surface protrusions on the peeled surface of Example 3 is 8 of the count of protrusions on the surface not peeled from the second polymer layer.
A stretched polyethylene-2,6-naphthalate film having 0% or more. 5. The longitudinal Young's modulus is 650 to 1000 k.
oriented polyethylene-2,6-naphthalate film according to claim 3 or 4, wherein the range of g / mm ^2. 6. In a temperature dimensional change curve under a vertical load, a dimensional change with respect to a film original length up to a temperature of 200 ° C. is 1% or less, and a dimensional change with respect to the film original length up to 230 ° C. 6. The stretched polyethylene-2,6-naphthalate film according to claim 3, which is within 3%. 7. At least one selected from the group consisting of a urethane resin, a polyester resin, an acrylic resin, and a vinyl resin-modified polyester resin is provided on at least one surface of the multilayer film before the crystal orientation of the first polymer layer is completed. The outermost first polymer layer is peeled off from the multilayer stretched film according to any one of claims 1 to 2, which has an easily adhesive layer obtained by applying an aqueous coating liquid as a component, drying, stretching, and further performing a heat treatment. 7. The stretched polyethylene-2,6 according to claim 3, wherein said polyethylene-2,6-naphthalate film is obtained, and said easy-adhesive layer is laminated on a surface of said film which is not peeled off from said second polymer layer. -Naphthalate films. 8. The stretched polyethylene according to claim 3, which is used as a base film for a thermal transfer printer ribbon.
2,6-naphthalate film.