JP2004174970A - Biaxially-oriented laminated polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soft polyester film having flexibility and transparency and excellent in slipping characteristics. <P>SOLUTION: The biaxially-oriented laminated polyester film is a co-extrusion laminated film comprising at least three layers, A, B, and C of polyester. The outermost layers, A and C layers, consist of a polyester which uses 1,4-cyclohexane dimethanol as one of the glycol components and which contains 0.01-1.0 wt.% of an inactive particle having an average particular size of 0.1-5.0 μm. The intermediate layer, B layer, consists of a polyester mainly composed of an aliphatic or cycloaliphatic diol component and a polyalkylene ether glycol component having a number average mol.wt. of 300-4,000. The proportion of the thickness of the B layer occupying in the total thickness of the film is 60-95%, and a Young's modulus at least in one direction of the film is 0.1-3.5 GPa. <P>COPYRIGHT: (C)2004,JPO

Description

【００５６】
上記表１中、ＣＨＤＭは１，４−シクロヘキサンジメタノール、ＴＰＡはテレフタル酸、ＥＧはエチレングリコール、ＰＴＭＧはポリテトラメチレンエーテルグリコールをそれぞれ意味する。
【００５７】
【表２】

【００５８】
本発明の要件を満たす実施例１〜３の二軸配向積層ポリエステルフィルムは、柔軟性、透明性、滑り性、巻き特性、耐ブロッキング性に優れるものであった。これに対し、比較例１〜１３の積層ポリエステルフィルムは、本発明の要件を満たしていないため、フィルムの柔軟性、透明性、滑り性、巻き特性、耐ブロッキング性に劣るものであった。
【００５９】
【発明の効果】
以上、詳述したように、本発明の二軸配向積層ポリエステルフィルムは、柔軟性、透明性、滑り性、巻き特性、耐ブロッキング性に優れるものであり、その工業的価値は高い。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a biaxially oriented laminated polyester film. More specifically, the present invention relates to a laminated flexible polyester film having flexibility, transparency, slipperiness, and blocking resistance, and having excellent winding properties.
[0002]
[Prior art]
Biaxially stretched polyester film represented by polyethylene terephthalate is excellent in physical properties such as transparency, mechanical strength, dimensional stability, and chemical properties such as chemical resistance. It is used in a wide range of fields such as industrial materials. However, since the biaxially stretched polyester film lacks flexibility, it cannot have deformation followability to an external force after being formed into a fixed shape, and its use is limited (for example, Patent Documents 1 and 2). etc).
[0003]
[Patent Document 1] JP-A-2001-34931
[Patent Document 2] Japanese Patent Application Laid-Open No. Hei 10-321559
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and a problem to be solved is to provide a flexible polyester film having flexibility, transparency, and excellent slipperiness.
[0005]
[Means for Solving the Problems]
The present inventor has conducted intensive studies in view of the above circumstances, and as a result, has found that a film having a specific configuration can easily solve the above-mentioned problems, and has completed the present invention.
That is, the gist of the present invention is a co-extruded laminated film including at least three polyester layers of an A layer, a B layer, and a C layer. The intermediate layer B is composed of a polyester containing 0.01 to 1.0% by weight of inert fine particles of 1 to 5.0 μm and having 1,4-cyclohexanedimethanol as one of the glycol components. Component, a polyester having an aliphatic or alicyclic diol component and a polyalkylene ether glycol component having a number average molecular weight of 300 to 4000 as a main component, and the thickness ratio of the B layer to the total film thickness is 60 to 95%. Characterized in that the film has a Young's modulus in at least one direction of 0.1 to 3.5 GPa. Exist for.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The polyester film of the present invention is a film in which at least three layers are extruded from an extrusion die by a so-called co-extrusion method, and is a film which is later oriented biaxially in a vertical direction and a horizontal direction.
In the present invention, the polyester constituting the outermost layers A and C is preferably composed of a polyester comprising an aromatic dicarboxylic acid and a glycol component.
[0007]
Examples of the aromatic dicarboxylic acid constituting the polyester include terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. As a glycol component, 1,4-cyclohexanedimethanol is an essential component, and other glycol components include ethylene glycol, diethylene glycol, trimethylene glycol, neopentyl glycol and the like.
In any case, the polyester used in the present invention must have 1,4-cyclohexanedimethanol as one component as a glycol component, and its content is usually 10 to 35 mol%, preferably 15 to 30 mol%. %, More preferably 20 to 30 mol%. 1,4-cyclohexanedimethanol, which is essential as a glycol component of the polyester of the present invention, has cis and trans isomers depending on the bonding position of the hydroxymethyl group to the cyclohexane ring, and the cyclohexane ring itself has a chair type or a boat type. Because of the presence, the crystallinity, melting point and the like are different, but in the present invention, the kind of 1,4-cyclohexanedimethanol used is not particularly limited.
[0008]
The polyester constituting the intermediate layer B of the film of the present invention is a polyester mainly composed of a dicarboxylic acid component, an aliphatic or alicyclic diol component and a polyalkylene ether glycol having a number average molecular weight of 300 to 4000. It is. The term "main component" as used herein means that 80% by weight or more of all the components are occupied by the above components. As for the constituent components, for example, the polyester B layer can be decomposed with an alkali and analyzed by chromatography. It is preferable that 50 mol% or more of the dicarboxylic acid component constituting the B layer is terephthalic acid, but another dicarboxylic acid component may be copolymerized. Specific examples of the carboxylic acid component other than terephthalic acid include, for example, isophthalic acid, orthophthalic acid, phenylenedioxydiacetic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, Aromatic dicarboxylic acids such as 4,4'-diphenylethercarboxylic acid, 4,4'-diphenylcarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4 -Alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid, etc., aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, etc., among which isophthalic acid, 2,6-naphthalenedicarboxylic acid One or more selected from acids and cyclohexanedicarboxylic acids are preferred.
[0009]
In the present invention, at the stage of the raw material, the dicarboxylic acid component may contain, for example, an ester-forming derivative such as an alkyl ester having about 1 to 4 carbon atoms.
As the aliphatic or alicyclic diol constituting the B layer, it is preferable that 50 mol% or more is ethylene glycol, but other aliphatic or alicyclic diol components are copolymerized. Is also good. Specific examples of the aliphatic or alicyclic diol component other than ethylene glycol include 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,4-butanediol. 1,1-pentanediol, 1,6-hexanediol, 1,10-decanediol, 2,2-dimethyl-1,3-propanediol, aliphatic diols such as diethylene glycol, 1,1-cyclohexanedimethanol, Alicyclic diols such as 1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol, 1,2-cyclohexane diol, and 1,4-cyclohexane diol; 1,4-butanediol, diethylene glycol, 1,4-cyclohexanedimeta Lumpur, one or more selected from 2,2-dimethyl-1,3-propanediol are preferred.
[0010]
In the present invention, the aliphatic or alicyclic diol component may be an ester-forming derivative at the raw material stage.
The content of the aliphatic or alicyclic diol component other than ethylene glycol is usually 30 mol% or less, preferably 5 to 30 mol%, more preferably 10 to 20 mol% of the total diol component. By copolymerizing an aliphatic or alicyclic diol component other than ethylene glycol, flexibility and transparency may be improved.However, when the copolymerization amount is outside the above range, mechanical properties of the obtained copolymerized polyester film are reduced. The properties are inferior.
[0011]
In the B layer of the polyester film of the present invention, furthermore, for example, 4,4-dihydroxybiphenyl, 2,2-bis (4′-hydroxyphenyl) propane, and the like, as long as the effects of the present invention are not impaired. Aromatic diols such as 2,2-bis (4′-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, glycolic acid, p-hydroxy Hydroxycarboxylic acids and alkoxycarboxylic acids such as benzoic acid and p-β-hydroxyethoxybenzoic acid; monofunctional components such as stearic acid, stearyl alcohol, benzyl alcohol, benzoic acid, t-butylbenzoic acid, and benzoylbenzoic acid; tricarbaryl Acid, hexanetricarboxylic acid, trimellitic acid, trimesic acid, pyro Trifunctional such as lithic acid, benzophenonetetracarboxylic acid, naphthalenetetracarboxylic acid, 1,2,6-hexanetriol, gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sorbitol, dipentaerythritol and polyglycerol The above polyfunctional components may be copolymerized.
[0012]
The layer B of the polyester film of the present invention needs to contain a polyalkylene ether glycol as a component, and has a number average molecular weight of 300 to 4,000, preferably 400 to 3,000, more preferably 500 to 2,000. When the number average molecular weight is less than 300, the heat resistance of the film is inferior, or a low molecular weight substance is precipitated. On the other hand, when the number average molecular weight exceeds 4000, the transparency of the film is poor.
Examples of the polyalkylene ether glycol include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene ether glycol, polyhexamethylene glycol, and a block or random copolymer of ethylene oxide and propylene oxide. Among them, polytetramethylene ether glycol is preferred.
[0013]
A plurality of polyalkylene ether glycols having different number average molecular weights may be used in combination. When two or more are used in combination, the value measured by mixing uniformly may be within the above range.
Here, the number average molecular weight of polytellamethylene glycol can be measured by a general method such as gel permeation chromatography.
The polyalkylene ether glycol is preferably contained in the copolymerized polyester in an amount of 5 to 35% by weight, more preferably 10 to 30% by weight. When the content of the polyalkylene ether glycol is less than 5% by weight, the flexibility of the film tends to be poor. On the other hand, if it exceeds 35% by weight, the flexibility of the film is excellent, but the transparency of the film may be impaired.
[0014]
The polyester resin constituting the film of the present invention is basically composed of a dicarboxylic acid component, a diol component and a polyalkylene ether glycol component, and a component that is further added if necessary, using a conventional method for producing a polyester resin, that is, It is produced palindrically or continuously by a direct polymerization method or a transesterification method.
Here, the polyalkylene ether glycol and optionally used copolymerization components can be added at any stage of the polycondensation reaction process.
Furthermore, the polyester of the invention can also be obtained by previously producing an oligomer having a low degree of polymerization comprising a dicarboxylic acid and an aliphatic and / or alicyclic diol, and polycondensing the oligomer with a polyalkylene ether glycol. it can.
[0015]
The resin obtained by the polycondensation reaction is usually withdrawn in the form of a strand from a withdrawal port provided at the bottom of the polycondensation reaction tank, and cut with a cutter with or after cooling with water, into pellets. Furthermore, the pellets after the polycondensation are subjected to a solid phase polycondensation by heat treatment, whereby the degree of polymerization can be further increased and acetaldehyde, low molecular oligomer, and the like, which are reaction by-products, can be reduced.
[0016]
In the production method, the esterification reaction is performed, if necessary, for example, in the presence of an esterification catalyst such as an organic acid salt such as antimony trioxide, antimony, titanium, magnesium, or calcium, or an organic metal compound. The exchange reaction is performed, if necessary, in the presence of an ester exchange catalyst such as an organic acid salt such as lithium, potassium, sodium, magnesium, calcium, manganese, titanium, or zinc, or an organometallic compound.
The polycondensation reaction is carried out, for example, in the presence of orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid and phosphorus compounds such as esters and organic acid salts thereof, and, for example, antimony trioxide, germanium dioxide, tetroxide. This is performed in the presence of a metal compound such as germanium, or a polycondensation catalyst such as an organic acid salt such as antimony, germanium, zinc, titanium, or cobalt, or an organic metal compound. Among these polycondensation catalysts, one or more selected from tetrabutoxytitanate, antimony trioxide, and germanium dioxide are preferably used.
[0017]
Furthermore, in order to promote defoaming in the polycondensation process, it is preferable to add an antifoaming agent such as silicone oil.
The polyester constituting the outermost layers A and C of the film of the present invention preferably contains inert fine particles in order to impart anti-blocking properties, slipperiness, and the like. The content is 0.01 to 1.0% by weight, preferably 0.05 to 0.5% by weight, more preferably 0.05 to 0.3% by weight, based on the film. When the content of the inert fine particles is less than 0.01% by weight, the transparency is excellent, but the handleability of the slippery film is poor, which is not preferable. On the other hand, when the content of the inert fine particles exceeds 1.0% by weight, the lubricity is excellent, but the transparency is deteriorated and the particles aggregate to form coarse projections, which is not preferable.
[0018]
Examples of the inert fine particles used in the present invention include inorganic particles such as calcium carbonate, silica, calcium phosphate, kaolin, talc, titanium dioxide, alumina, barium sulfate, lithium fluoride, zeolite, and molybdenum sulfide; calcium oxalate; Examples include organic particles such as molecular particles, but are not limited thereto.
[0019]
The average particle size of the inert fine particles used is in the range of 0.1 to 5.0 μm, preferably 0.2 to 4.0 μm, and more preferably 0.3 to 3.0 μm. If the average particle size is less than 0.1 μm, the transparency is excellent, but the winding properties in the film production process are inferior, which is not preferable. On the other hand, when the thickness exceeds 5.0 μm, the lubricity is excellent, but the degree of surface roughening of the film becomes too large, and the transparency is impaired, and a lumpy defect (marbling) is likely to occur. Not preferred.
A known method can be adopted as a method for incorporating inert fine particles into the polyester constituting the outermost layers A and C. For example, it can be added at any stage of producing the polyester, but is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or after the end of the transesterification reaction and before the start of the polycondensation reaction. Then, the polycondensation reaction may proceed. Further, using a kneading extruder with a vent, a method of blending a slurry of particles dispersed in water or an organic solvent having a boiling point of 200 ° C. or less with a polyester raw material, or particles dried using a kneading extruder And a method of blending the polyester raw material.
[0020]
It is also a preferable method that the layer A and the layer C contain an organic lubricant in addition to the above-mentioned particles in order to improve the lubricity of the film.
The kind of the organic lubricant is not particularly limited, but an aliphatic compound, an aliphatic ester, an alkylenebisaliphatic, an aromatic amide and the like are preferable. As the aliphatic compound, a compound having a large number of carbon atoms, such as montanic acid, is preferable. Examples of the aliphatic ester include montanic acid ethylene glycol ester. Examples of the alkylenebisaliphatic and aromatic amides include hexamethylenebisbehenamide, N, N'-distearylterephthalamide, hexamethylenebisstearylamide, hexamethylenebisstearylamide and the like. The content of these organic lubricants in the film is preferably 500 ppm or less, more preferably 200 ppm or less. If these lubricants are mixed in an excessively large amount, there is a possibility that the adhesiveness may be reduced when various coatings are applied to the film, or the yellow tint of the film may become too strong.
[0021]
In the present invention, the center line average roughness (Ra) of the film surface is in the range of 0.010 to 0.100 μm in order to highly satisfy the slipperiness, winding property, blocking resistance, and workability. The range is preferably 0.015 to 0.080 μm, and more preferably 0.020 to 0.060 μm, and it is desirable to appropriately select conditions so as to be within such a range.
The degree of plane orientation (ΔP) of the polyester film of the present invention is usually 0.030 to 0.150, preferably 0.040 to 0.145, more preferably 0.050 to 0.140. When the content is in the above range, flexibility and handleability of the film are improved.
[0022]
In the present invention, the composite polyester film needs to have a Young's modulus in at least one direction in the range of 0.1 to 3.5 GPa, preferably 0.1 to 3.0 GPa, more preferably 0.2 GPa to 0.2 GPa. It is in the range of 2.5 GPa. The Young's modulus (Y) in all directions of the film is preferably in the above range. If the Young's modulus (Y) is less than 0.1 GPa, it is difficult to form the film itself, and if it exceeds 3.5 GPa, the flexibility and rubbing resistance of the film are impaired.
In the present invention, the tensile elongation at break in the longitudinal direction and the width direction of the composited polyester film is usually in the range of 100 to 200%, preferably 110 to 190%, more preferably 120 to 180%. If the tensile elongation at break is less than 100%, the flexibility tends to be poor. On the other hand, when the tensile elongation at break exceeds 200%, the film is too soft, and the winding work and the handleability of the film may be deteriorated due to wrinkles and elongation.
[0023]
In the polyester film of the present invention, the ratio of the thickness of the layer B to the total thickness of the film is from 60 to 95%, preferably from 65 to 95%, particularly preferably from 70 to 95%. If this value is less than 60%, the flexibility is unfavorably deteriorated. On the other hand, if it exceeds 95%, it is not preferable because the lamination thickness in the width direction becomes uneven.
In the present invention, a coating layer may be provided in order to impart adhesiveness, antistatic property and lubricity to the composited polyester film. As components constituting the coating layer, resins such as polyester, polyamide, polystyrene, polyacrylate, polycarbonate, polyarylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyral, polyvinyl alcohol, polyurethane, and copolymers of these resins, etc. Can be mentioned. One or two or more of such resins may be simultaneously contained.
[0024]
As a method of applying the above-mentioned coating liquid to a film, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, and other coating apparatuses described in “Coating System”, written by Yuji Harasaki, Maki Shoten, 1979 Can be used. The coating layer may be provided in the film manufacturing process, or may be applied after the film is manufactured. In particular, from the viewpoint of uniformity of coating thickness and production efficiency, a method of coating in a film manufacturing process is preferable.
As a method of applying in the film manufacturing process, a coating liquid is applied to an unstretched sheet, a method of sequentially or simultaneously biaxially stretching, applying to a uniaxially stretched film, and further in a direction perpendicular to the uniaxially stretching direction. There is a method of stretching, or a method of applying to a biaxially stretched film and further stretching in the transverse and / or longitudinal directions.
[0025]
The thickness of the coating layer is usually in the range of 0.005 to 1.0 μm, preferably in the range of 0.01 to 0.5 μm. When the coating thickness exceeds 1.0 μm, continuity during film production may be deteriorated. On the other hand, when the coating thickness is less than 0.005 μm, coating dropping and coating unevenness tend to occur.
The coating layer may be provided on only one side of the film, but is preferably provided on both sides. In addition, when the coating is applied to only one surface, a coating layer other than the coating layer of the present invention may be formed on the opposite surface as needed to impart other properties to the film of the present invention.
The film may be subjected to a chemical treatment or a discharge treatment before application in order to improve the film coating property and adhesiveness of the coating agent. Further, in order to improve the adhesiveness, coatability, etc. of the coating layer in the film of the present invention, the coating layer can be subjected to a discharge treatment after the formation of the coating layer.
[0026]
Next, the method for producing the polyester film of the present invention will be specifically described, but is not limited to the following examples as long as the constitutional requirements of the present invention are satisfied.
That is, using the polyester raw material described above, using a plurality of extruders, a plurality of layers of a multi-manifold die or a feed block, laminating each polyester, extruding a plurality of layers of a molten sheet from a die, and cooling rolls. A method of obtaining an unstretched sheet by cooling and solidifying is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to increase the adhesion between the sheet and the rotary cooling roll, and the electrostatic application adhesion method and / or the liquid application adhesion method are preferably employed.
[0027]
Next, the obtained unstretched sheet is biaxially stretched and biaxially oriented. That is, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 40 to 100 ° C., preferably 60 to 90 ° C., and the stretching ratio is usually 3.0 to 5 times, preferably 3.5 to 4.5 times. Next, stretching is performed in a direction orthogonal to the first-stage stretching direction. The stretching temperature is usually 50 to 100 ° C, preferably 60 to 95 ° C, and the stretching ratio is usually 3.0 to 5 times, preferably 3.5 to 4.5 times. In addition, a method of performing unidirectional stretching in two or more stages can be used, but in such a case, it is desirable that the final stretching ratio falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area magnification becomes 10 to 40 times.
[0028]
The thus obtained film is preferably subjected to a heat treatment at 150 to 210 ° C. for 1 to 600 seconds. Further, at this time, a method of relaxing 0.1 to 20% in the vertical and / or horizontal direction in the maximum temperature zone of the heat treatment and / or the cooling zone at the outlet of the heat treatment is preferable. Further, re-longitudinal stretching and re-lateral stretching can be added as necessary.
[0029]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The methods for measuring physical properties and characteristics used in the present invention are as follows. In Examples and Comparative Examples, “parts” means “parts by weight”.
[0030]
(1) Average particle size (μm)
It measured with the centrifugal sedimentation type particle size distribution analyzer (SP-CP3 type) made by Shimadzu Corporation.
In the present invention, the average particle diameter is defined as an average particle diameter of 50% of an integrated volume fraction of an equivalent spherical distribution regardless of its shape.
[0031]
(2) Intrinsic viscosity of polymer [η] (dl / g)
1 g of the polymer was dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) and measured at 30 ° C. with an Ubbelohde viscometer.
[0032]
(3) Film surface roughness (μm)
The surface roughness is defined as the center line average roughness Ra (μm). It was obtained as follows using a surface roughness measuring instrument (SE-3F type) manufactured by Kosaka Laboratory Co., Ltd. That is, a portion of the reference length L (2.5 mm) is extracted from the film cross-sectional curve in the direction of the center line, and the center line of the extracted portion is the x-axis, and the direction of the vertical magnification is the y-axis, and the roughness curve y = f When represented by (x), the value given by the following equation is represented by μm. The center line average roughness was obtained by calculating ten cross-sectional curves from the surface of the sample film, and expressing the average value of the center line average roughness of the extracted portion obtained from these cross-sectional curves. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.
Ra = (1 / L) ∫₀ ¹| F (x) | dx
[0033]
(4) Degree of plane orientation of film (ΔP)
Using an Abbe refractometer manufactured by Atago Optical Co., the maximum value of the refractive index in the plane of the film (nγ), the refractive index in the orthogonal direction (nβ) and the refractive index in the thickness direction of the film (nα) were measured. The degree of plane orientation (ΔP) was calculated from the equation. The measurement of the refractive index was performed at 23 ° C. using a sodium D line.
ΔP = (nγ + nβ) / 2−nα
[0034]
(4) Young's modulus of film (GPa)
Using a tensile tester (model 2001) manufactured by Intesco Corporation, a sample film having a length (between chucks) of 300 mm and a width of 20 mm was placed at a temperature of 23 ° C. and a humidity of 50% RH at a rate of 25 mm / min. The tension was calculated at the following speed using the initial linear portion of the tensile stress-strain curve.
Y = Δσ / Δε
(Where Y is the Young's modulus (GPa), Δσ is the stress difference (GPa) due to the original average cross-sectional area between two points on the straight line, and Δε is the strain difference between the two points / initial length (−). Represents)
[0035]
(5) Tensile elongation at break of film (%)
Using a tensile tester (model 2001) manufactured by Intesco Corporation, a sample film having a length (between chucks) of 50 mm and a width of 15 mm was placed at a temperature of 23 ° C. and a humidity of 50% RH at a rate of 200 mm / min. , And the tensile stress-strain curve was determined by the following equation.
E = (L−L₀) × 100 ÷ L₀
(Where E is the tensile elongation at break (%), L is the film length at break (mm), L₀Represents the original film length (mm))
[0036]
(6) Slip property of film
Two films cut to a width of 15 mm and a length of 150 mm are stacked on a smooth glass plate, and a rubber plate is placed thereon, and the film contact pressure of the two films is set to 2 g / cm.²The frictional force was measured by sliding the films at 20 mm / min, and the coefficient of friction at the point of sliding by 5 mm was determined as the dynamic friction coefficient. The measurement was performed in an atmosphere at a temperature of 23 ° C. and a humidity of 50% RH.
[0037]
(7) Film haze (%)
According to JIS-K7136, the turbidity of the film was measured with a spectroscopic turbidity meter (NDH-2000) manufactured by Nippon Denshoku Industries.
[0038]
(8) Lamination thickness of film
This was performed by observing the cross section of the film with a transmission electron microscope (TEM). That is, a small piece of the film sample was embedded in a resin in which a curing agent and an accelerator were mixed with an epoxy resin, and a section having a thickness of about 200 nm was prepared with an ultramicrotome to obtain a sample for observation. The obtained sample was observed with a transmission electron microscope (H-9000) manufactured by Hitachi, Ltd. In the cross section, the interface is observed by light and dark almost in parallel with the film surface. The distance between the interface and the surface of the film was averaged for one transmission electron micrograph and used as the thickness. However, the acceleration voltage was set at 300 KV, and the magnification was set within the range of 10,000 to 100,000 times according to the surface layer thickness. This was performed on at least 50 photographs, and 10 points from the thicker and 10 points from the thinner measured values were deleted, and the arithmetic mean value at 30 points was defined as the film thickness. Based on this film thickness, the intermediate layer ratio was calculated by the following equation.
Middle layer ratio = (thickness of middle layer / total thickness) × 100 (%)
[0039]
(9) Film winding characteristics
Films produced on a paper tube having a diameter of 15 cm at a line speed of about 170 m / min were inspected for the 3000 m winding end face and the state of the winding roll surface defect, and classified into the following four ranks.
A: The end faces are all aligned, and there is no roll surface defect.
B: The end faces are almost aligned, and there is no roll surface defect.
C: A part of the end face is irregular, and a slight roll surface defect is observed.
D: A considerable portion of the end face is irregular, and many roll surface defects are observed.
[0040]
(10) Blocking resistance
The films were overlaid and pressed. The pressing was performed in an atmosphere of a temperature of 40 ° C. and a humidity of 80% RH at a pressure of 98 Pa for 20 hours. Then, after leaving the film in a room at room temperature of 23 ° C. and humidity of 50% RH for one day and night, the films were peeled off from each other by ASTM-1893, and the degree of blocking was determined based on the peeling load and determined based on the criteria.
…: Good. Peeling load less than 20g
△: Normal. Peeling load 20 g or more and less than 50 g
×: Bad. Peeling load 50g or more
[0041]
Example 1
(Production of polyester A)
100 parts of dimethyl terephthalate, 85 parts of ethylene glycol, 15 parts of 1,4-cyclohexanedimethanol, and 0.005% by weight of tetrabutyl titanate were placed in a reactor, and the reaction initiation temperature was set to 150 ° C. The temperature was gradually increased to 210 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially completed. After adding 0.005% by weight of tetrabutyl titanate to the reaction mixture, 0.1 part of amorphous fine silica particles having an average particle diameter of 2.4 μm was added as an ethylene glycol slurry to carry out a polycondensation reaction. . At this time, the temperature was gradually raised from 220 ° C. to 250 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally was 40 Pa. After 5 hours from the start of the reaction, when the reaction was obtained, the reaction was stopped, the polymer was drawn out into a strand under nitrogen pressure, and after cooling, the polymer was cut with a pelletizer and recovered in the form of pellets.
The intrinsic viscosity of the thus obtained polyester resin pellet was 0.66.
[0042]
(Production of polyester B)
59 parts of terephthalic acid, 21 parts of ethylene glycol, 20 parts of polytetramethylene glycol (number average molecular weight 1000), 0.009 parts of tetrabutoxytitanate, 0.025 parts of ethyl acid phosphate, 0.025 parts of ethyl acetate as a catalyst and a co-catalyst. 05 parts were placed in a reactor, and a polyester resin was obtained by a direct polymerization method at 270 ° C. and 400 Pa. The polyester resin was withdrawn in a strand form from the polymerization tank, cooled, and then cut with a pelletizer to collect in a pellet form.
The intrinsic viscosity of the thus obtained polyester resin pellet was 0.79.
[0043]
(Manufacture of polyester film)
Polyester A and polyester B are fed to separate vented twin-screw extruders, melt-kneaded under reduced pressure of the vents, and these polymers are combined in a feed block and laminated, and a temperature of 20 ° C. is passed through a slit die. The sheet was extruded into a sheet on a rotating cooling roll, and rapidly cooled by a rotating cooling roll using an electrostatic contact method to obtain a laminated unstretched sheet. Next, the obtained sheet was stretched 3.5 times in length at 60 ° C. Next, the film was guided to a tenter and laterally stretched 3.5 times at 75 ° C., and then heat-treated at 200 ° C. for 3 seconds, and the layer configuration was polyester A / polyester B / polyester A, and the thickness of each layer was 2/21 / 2 (μm) to obtain a laminated film having a total thickness of 25 μm.
[0044]
Example 2
In Example 1, the layer composition was polyester A / polyester B / polyester A, and the thickness of each layer was 2 in the same manner as in Example 1 except that the composition of polyester B was changed as shown in Table 1. A laminated film having a thickness of 25 μm, which was / 21/2 (μm), was obtained.
[0045]
Example 3
In Example 1, the layer composition was polyester A / polyester B / polyester A, and the thickness of each layer was 2 in the same manner as in Example 1 except that the composition of polyester B was changed as shown in Table 1. A laminated film having a thickness of 25 μm, which was / 21/2 (μm), was obtained.
[0046]
Comparative Example 1
In Example 1, the layer constitution was set to polyester B / polyester B / polyester B, and a laminated film having a thickness of 25 μm in which the thickness of each layer was 2/21/2 (μm) was obtained.
[0047]
Comparative Example 2
In Example 1, the layer configuration was polyester A / polyester B / polyester A, except that the glycol component of polyester A, 1,4-cyclohexanedimethanol, was changed to 5 parts. A 25 μm-thick laminated film having a thickness of 2/21/2 (μm) was obtained.
[0048]
Comparative Example 3
In Example 1, the layer configuration was polyester A / polyester B / polyester A, except that the glycol component of polyester A, 1,4-cyclohexanedimethanol, was changed to 40 parts. A 25 μm-thick laminated film having a thickness of 2/21/2 (μm) was obtained.
[0049]
Comparative Example 4
In Example 1, except that the composition of the polyester B was changed as shown in Table 1, the layer configuration was changed to polyester A / polyester B / polyester A, and the thickness of each layer was 2 / A laminated film having a thickness of 25 μm, which is 21/2 (μm), was obtained.
[0050]
Comparative Example 5
In Example 1, each layer composition was polyester A / polyester B / polyester A, and the layer thickness was 2 in the same manner as in Example 1 except that the composition of polyester B was changed as shown in Table 1. A laminated film having a thickness of 25 μm, which was / 21/2 (μm), was obtained.
[0051]
Comparative Examples 6 and 7
In Example 1, the layer structure was changed to polyester A / polyester B / polyester A in the same manner as in Example 1 except that the number average molecular weight of the polytetramethylene ether glycol of the polyester B was changed to that shown in Table 1. There was obtained a laminated film having a thickness of 25 μm in which the thickness of each layer was 2/21/2 (μm).
[0052]
Comparative Example 8
In Example 1, the layer structure was polyester A / polyester B / polyester A, and a laminated film having a thickness of 25 μm in which each layer had a thickness of 6/13/6 (μm) was obtained.
[0053]
Comparative Example 9
In Example 1, the layer constitution was set to polyester A / polyester B / polyester A, and a laminated film having a thickness of 25 μm in which each layer had a thickness of 0.5 / 24 / 0.5 (μm) was obtained.
[0054]
Comparative Examples 10 to 13
In Example 1, the layer configuration was polyester A / polyester B / polyester A, in the same manner as in Example 1, except that the particle size and the concentration of the added particles of the polyester A were changed as shown in Table 1. A 25 μm-thick laminated film having a thickness of each layer of 2/21/2 (μm) was obtained.
[0055]
[Table 1]

[0056]
In Table 1, CHDM means 1,4-cyclohexanedimethanol, TPA means terephthalic acid, EG means ethylene glycol, and PTMG means polytetramethylene ether glycol.
[0057]
[Table 2]

[0058]
The biaxially oriented laminated polyester films of Examples 1 to 3 satisfying the requirements of the present invention were excellent in flexibility, transparency, slipperiness, winding characteristics, and blocking resistance. On the other hand, since the laminated polyester films of Comparative Examples 1 to 13 did not satisfy the requirements of the present invention, they were inferior in film flexibility, transparency, slipperiness, winding characteristics, and blocking resistance.
[0059]
【The invention's effect】
As described above in detail, the biaxially oriented laminated polyester film of the present invention is excellent in flexibility, transparency, slipperiness, winding properties, and blocking resistance, and has high industrial value.

Claims (1)

A co-extruded laminated film comprising at least three polyester layers, A layer, B layer and C layer, wherein the outermost layers A and C have an average particle diameter of 0.1 to 5.0 µm. The layer B, which is an intermediate layer, is composed of a polyester containing 0.01 to 1.0% by weight of fine particles and having 1,4-cyclohexanedimethanol as one of the glycol components. A diol component and a polyester having a polyalkylene ether glycol component having a number average molecular weight of 300 to 4,000 as a main component. A biaxially oriented laminated polyester film having a Young's modulus in the direction of 0.1 to 3.5 GPa.