JP3211364B2 - Laminated polyethylene-2,6-naphthalate film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to polyethylene-2,6
The present invention relates to a naphthalate film, and more particularly to a polyethylene-2,6-naphthalate film suitable as a magnetic recording medium.

[0002]

2. Description of the Related Art Conventionally, polyethylene terephthalate film is mainly used as a film used for industrial applications, and is excellent in mechanical and electrical properties. It is used in various fields such as magnetic tape applications, electrical insulation applications such as capacitors, packaging applications, photo and plate making applications. In particular, as a base material for a magnetic recording material, the base material had remarkably excellent characteristics and was in a situation where other films could not follow. However, in recent years, magnetic recording media have been rapidly improved, and from the viewpoint of improving information recording density, demands for thinning and flattening the base film of the magnetic recording media have become more severe than ever. Was. In order to improve the recording area per unit volume by reducing the thickness, it has been difficult to achieve a sufficient reduction in thickness of the polyethylene terephthalate film while maintaining practical strength. Furthermore, such base density recording medium - but the scan film surface is Ru is required to be more flat, appears various evils accordance film surface becomes flat. For example, like a magnetic tape,
When the metal pin and the tape come into contact with each other at high speed, friction and wear between the two become large, causing scratches on the tape,
Wear powder is generated.

[0003]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems, and as a result, have found that certain polyethylene-2,
6-naphthalate film was found to be useful, and the present invention was completed.

That is, the gist of the present invention is to provide an aqueous polyester or aqueous polyacrylate containing 0.5 to 20% by weight of a lubricant on at least one surface of a polyethylene-2,6-naphthalate film having a thickness of 9 μ or less. And a laminated film having a coating layer made of at least one resin selected from water-based polyurethane, and simultaneously satisfying the following formulas (1) to (4). F5 value in film longitudinal direction ≧ 1.5 × 10 ⁸ Pa ... Young's modulus in film longitudinal direction ≧ 5.9 × 10 ⁹ Pa… Young's modulus in film lateral direction ≧ 5.9 × 10 ⁹ Pa… 70 ° ≦ coating layer Water droplet contact angle ≤ 85 ° on the surface ...

Hereinafter, the present invention will be described in more detail. In the present invention, polyethylene-2,6-naphthalate means that at least 80 mol% of its constituent units are ethylene-2,6-naphthalate.
-Polyethylene-2,6-naphthalate which is naphthalate. Examples of copolymerization components other than the above-mentioned superior constituents include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol and polytetramethylene glycol, and terephthalic acid. Dicarboxylic acid components such as isophthalic acid, 2,7-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid and ester-forming derivatives thereof, oxybenzoic acid and ester-forming derivatives thereof Can be used.

The polyethylene-2,6-naphthalate used in the present invention has an intrinsic viscosity of usually 0.40 or more, preferably 0.5 to 0. 7 range. The carboxyl group value of the polyethylene-2,6-naphthalate used in the present invention is preferably 15 to 100 equivalents / ton, more preferably 40 to 95 equivalents / ton, and particularly preferably 50 to 90 equivalents / ton. is there. Since the adhesion to the coating layer is improved by the presence of the carboxyl group, the carboxyl group value is preferably 15 or more. If the carboxyl group value is too large, the heat resistance and mechanical properties of polyethylene-2,6-naphthalate have. It is preferable that the ratio be 100 or less, since this may deteriorate the mechanical characteristics.

The polyethylene-2,6-naphthalate film of the present invention contains so-called added particles, precipitated particles, catalyst residues, etc., which form projections on the film surface, as long as the electromagnetic conversion characteristics described below are not deteriorated. May be. In addition, as an additive other than the above-mentioned protrusion-forming agent, if necessary, an antistatic agent, a stabilizer, a lubricant, a crosslinking agent, an anti-blocking agent, an antioxidant, a coloring agent, a light blocking agent,
It may contain an ultraviolet absorber or the like. The polyethylene-2,6-naphthalate film of the present invention may have a multilayer structure as long as the properties finally obtained satisfy the requirements of the present invention. In the case of a multilayer structure, some of the layers may be layers other than the polyethylene-2,6-naphthalate film.

In the present invention, a coating layer containing a lubricant is provided on at least one side of the polyethylene-2,6-naphthalate film in order to impart lubricity while maintaining the surface flatness of the base film. . As the lubricant used in the present invention, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, amphoteric surfactants, nonionic surfactants, fluorine surfactants, organic carboxylic acids and derivatives thereof , Higher aliphatic alcohols, paraffins, waxes and the like, and particularly preferred are polyolefins and silicone-based lubricants. Examples of the polyolefin-based lubricant include waxes, resins, and rubber-like materials such as polyethylene, propylene, 1-butene, and a homo- or copolymer of 1-olefin-based unsaturated hydrocarbons such as 4-methyl-1-pentene. , Polypropylene, poly-1-butene, poly-4-methyl-
1-pentene, ethylene-propylene copolymer, aliphatic dicarboxylic acids such as azelaic acid and sebacic acid, oxycarboxylic acids such as oxybenzoic acid, and ester-forming derivatives thereof can be used.

[0009] Silicon-based lubricants include unmodified silicones such as dimethylpolysiloxane, fatty acids,
Any of silicones modified with polar groups such as polyethers, alcohols and alkyl groups can be used. Silicone modified with a polar group is particularly preferred because of its good affinity with the binder resin. Further, the lubricant used in the present invention is blended in at least one resin selected from the group consisting of aqueous polyurethane, aqueous polyacryl and aqueous polyester as a binder, applied to a polyester film, stretched, and heat-fixed. It is preferable that an appropriate amount of water springs on the surface of the membrane. The lubricant on the surface layer of the coating film that formed well forms a lubricious layer on the surface layer of the film, thereby improving the handling workability when reworking the film, preventing contact scratches with the transport roll,
The effect of preventing adhesion to the heating roll becomes remarkable.

The content of the lubricant is 0.5 to 20 in the coating layer.
% By weight. If the content is 0.5% by weight or less, the amount of the lubricant flowing out to the surface layer of the coating film is too small to exert a sufficient effect. On the other hand, when the content exceeds 20% by weight, the amount of the swelling is too large, and the effect of the binder easily adhering to the overcoat ink or the like is impaired. The most effective anti-adhesion effect is obtained when the lubricant that has sprung out is coordinated with the hydrophobic group on the outside. As a measure of this coordination situation, when expressed in terms of the contact angle of a water drop,
It was found that the anti-adhesion effect was exhibited when the water droplet contact angle on the coating film surface was within the range of 70 to 85 °.

In order to further enhance the lubricating effect and the anti-adhesion effect, it is preferable to incorporate particles in the coating layer. Examples of the type of particles used include inorganic particles, organic particles, and the like.Examples of the inorganic particles include silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, calcium phosphate, titanium oxide,
Barium sulfate, carbon black, molybdenum sulfide, antimony oxide sol and the like can be used. The organic particles include polystyrene, polyethylene, polyamide, polyester, polyacrylate, epoxy resin, homo- or copolymers of polyvinyl acetate or polyvinyl chloride, etc., and fine particles containing a crosslinking agent as necessary, silicone resin, fluorine, etc. Fine particles such as a resin may be used. As the binder resin constituting the coating layer, at least one resin selected from aqueous polyesters, aqueous polyacrylates and aqueous polyurethanes having excellent adhesion to a magnetic layer or the like is used, and a copolymer of these resins is used. It may be contained.

As the components constituting the aqueous polyester resin, the following polyvalent carboxylic acids and polyvalent hydroxy compounds can be exemplified. That is, terephthalic acid, isophthalic acid, orthophthalic acid,
Phthalic 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, glutar 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; Compounds include ethylene glycol, 1,2-propylene glycol, 1,3
-Propylene glycol, 1,3-propanediol,
1,4-butanediol, 1,6-hexanediol,
2-methyl-1,5-pentaneddiol, neopentyl glycol, 1,4-cyclohexanedimethanol, p
-Xylylene glycol, bisphenol A-ethylene 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.

[0013] One or more of these compounds are appropriately selected, and a polyester resin is synthesized by a conventional polycondensation reaction. In addition, in addition to the above,
A composite polymer having a polyester component, such as a so-called acrylic graft polyester or a polyester polyurethane obtained by chain-extending a polyester polyol with isocyanate, described in Japanese Patent No. 65633, is also included in the polyester resin of the present invention. When using water as the medium,
A coating agent forcibly dispersed by a surfactant or the like may be used, but a self-dispersion coating having a hydrophilic nonionic component such as polyethers or a cationic group such as a quaternary ammonium salt is preferable. And more preferably a water-soluble or water-dispersible resin coating agent having an anionic group. The resin having an anionic group as referred to herein is a resin obtained by bonding a compound having an anionic group to a resin by copolymerization, grafting, or the like, and includes sulfonic acid, carboxylic acid, phosphoric acid, and lithium salts and sodium salts thereof. , Potassium salts, ammonium salts and the like. The ratio of the anionic group to the resin solid content is as follows:
The range of 0.05 to 8% by weight is preferred. When the amount of the anionic group is less than 0.05% by weight, the water solubility or water dispersibility of the resin tends to deteriorate, and the amount of the anionic group is 8% by weight.
If the ratio exceeds the above range, the water resistance of the coating layer may be poor, or the films may adhere to each other due to moisture absorption.

The water-based polyacrylic used in the present invention is a water-soluble or water-dispersible acrylic resin, which preferably contains alkyl acrylate or alkyl methacrylate as a main component.
A water-soluble or water-dispersible resin containing 70 to 10 mol% of a vinyl monomer component having a functional group and being copolymerizable and having a mol% is preferred. When the alkyl acrylate or alkyl methacrylate in the acrylic resin is at least 30 mol%, the coating formability, the strength of the coating film, and the blocking resistance will be good. 90 mole% of alkyl acrylate or alkyl methacrylate in acrylic resin
In the following, by introducing a compound having a compound having a specific functional group as a copolymer component into an acrylic resin, it is possible to easily make water-soluble and water-dispersible and to stabilize the state for a long time. Improvement of the adhesion between the coating layer and the polyester film layer, improvement of the strength, water resistance and chemical resistance of the coating layer due to the reaction in the coating layer, and further improvement of the adhesion between the film of the present invention and other materials. Can be measured.

Examples of the alkyl group of the alkyl acrylate and the alkyl methacrylate include a methyl group and n-
Examples include a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 2-ethylhexyl group, a lauryl group, a stearyl group, and a cyclohexyl group. The vinyl monomer copolymerizable with the alkyl acrylate or alkyl methacrylate and having a functional group may be used to impart hydrophilicity to the resin to improve the water dispersibility of the resin, or to combine the resin with a polyester film or a coating layer. It is preferable to improve the adhesiveness with another coating layer provided thereon, or to have a functional group that improves the affinity with a polyester resin to be blended as a coating agent. A salt thereof, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylolated amide group, an amino group (including a substituted amino group) or an alkylolated amino group or a salt thereof;
Examples thereof include a hydroxyl group and an epoxy group, and 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.

As the vinyl monomer having a functional group copolymerizable with an alkyl acrylate or an alkyl methacrylate, compounds having a functional group such as a reactive functional group, a self-crosslinkable functional group, and a hydrophilic group can be used. Specifically, acrylic acid, methacrylic acid, itaconic acid, alkali metal salts such as maleic acid or alkaline earth metal salts,
Examples thereof include ammonium salts and maleic anhydride. 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,
Examples include methylolated acrylamide, methylolated methacrylamide, ureido vinyl ether, β-ureidoisobutyl vinyl ether, ureidoethyl acrylate, and the like.

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,
-Aminobutyl vinyl ether, dimethylaminoethyl methacrylate, dimethylaminoethyl vinyl ether, methylolated amino groups thereof, alkyl halides, quaternized with dimethyl sulfate, sultone and the like. Examples of the compound having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxyvinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, and polyethylene glycol. Monoacrylate,
Examples include polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, and polypropylene glycol monomethacrylate. Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

Other compounds that can be used in combination with the above compounds include acrylonitrile, styrenes, butyl vinyl ether, mono or dialkyl maleate, mono or dialkyl fumarate, mono or dialkyl itaconate, methyl vinyl ketone,
Examples include, but are not limited to, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, vinyl trimethoxysilane, and the like. The acrylic resin may contain a surfactant, but when the ratio of the acrylic resin to the polyester resin or the urethane resin is large, the low molecular weight surfactant contained in the acrylic resin is used. Is concentrated during the film formation process and accumulates at the interface between particles or migrates to the interface of the coating layer, causing problems in the mechanical strength of the coating layer, water resistance, and adhesion to the laminate. There are cases. In such a case,
A polymer obtained by so-called soap-free polymerization containing no surfactant can be used.

The method for producing an acrylic resin containing no surfactant is described in "Management Development Center Publishing Department, Edited by Management Development Center Publishing Department, published in January 1981," Water-soluble polymer / water-dispersed resin general technical data ". Use the method shown in p. 309 or the textbook of the lecture "Looking forward into the future from the latest research results-New development of emulsion and future technical issues" sponsored by the Industrial Technology Research Association (December 1981) Can be. For example, use of an oligomer or a polymer surfactant instead of a low molecular weight surfactant, introduction of a hydrophilic group into a polymer by use of a polymerization initiator such as potassium persulfate or ammonium persulfate, having a hydrophilic group Copolymerization of monomers, use of reactive surfactants, so-called shell-core type polymers in which the structure of the inner layer and outer layer of the dispersion particles are changed, and so-called water-dispersible acrylics containing no surfactant It can be used as a resin manufacturing technique.

The aqueous polyurethane used in the present invention refers to a water-soluble or water-dispersible polyurethane resin and is disclosed in JP-B-42-24194, JP-B-46-7720, JP-B-46-10193, and JP-B-Sho. 49-37
839, JP-A-50-123197, JP-A-53-126058, JP-A-54-13809
For example, a polyurethane resin described in JP-A No. 8 or the like or a polyurethane resin similar thereto can be used. The main components of the polyurethane-forming component are a polyisocyanate, a polyol, a chain extender, a crosslinking agent, and the like.

Examples of the polyisocyanate include tolylene diisocyanate, phenylene diisocyanate,
4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate and the like. Examples of the polyol, polyoxyethylene glycol, polyoxypropylene glycol, polyethers such as polyoxytetetramethylene glycol, polyethylene adipate, polyethylene butylene adipate, polyesters such as polycaprolactone, acrylic polyol, And castor oil.

Examples of the chain extender or the crosslinking agent include ethylene glycol, propylene glycol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine,
4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, water and the like. In order to make the compound water-soluble or water-dispersible, it may be forcibly dispersed with a surfactant or the like, but preferably, a hydrophilic nonionic component such as polyethers or a cation such as a quaternary ammonium salt is used. A self-dispersing coating agent having a functional group, more preferably a water-soluble or water-dispersible polyurethane resin coating agent having an anionic group is used.

The polyurethane resin having an anionic group can be obtained by a method using a compound having an anionic group as a polyol, a polyisocyanate compound, a chain extender or the like as a polyurethane-forming component, an unreacted isocyanate group of an produced polyurethane and an anion. It can be produced by a method of reacting a compound having an acidic group, a method of reacting a group having an active hydrogen of polyurethane with a specific compound, and the like.
When a compound having an anionic group is used as the polyurethane-forming component, for example, a compound obtained by a method of sulfonating an aromatic isocyanate compound, a diaminocarboxylate, a sulfate of an amino alcohol, or the like can be used.

The method of reacting an unreacted isocyanate group of a polyurethane with a compound having an anionic group includes, for example, bisulfite, aminosulfonic acid and salts thereof, aminocarboxylic acid and salts thereof, sulfate of amino alcohols and salts thereof. Salts, hydroxyacetic acid and salts thereof can be used. Methods for reacting a specific compound with a group having an active hydrogen of polyurethane include, for example, dicarboxylic anhydride, tetracarboxylic anhydride, sultone, lactone, epoxycarboxylic acid, epoxysulfonic acid, 2,4-dioxo-oxazolidine, isato Cyclic compounds such as acid anhydrides, hostons and carboxylate can be used.

The polyurethane resin used in the present invention has a polyol having a molecular weight of 300 to 20,000, a polyisocyanate, a chain extender having a reactive hydrogen atom, a group which reacts with an isocyanate group, and at least one anionic group. Resins consisting of compounds are preferred.
The anionic group in the polyurethane resin is -SO3H,
-OSO ₃ H, a lithium salt such as -COOH, sodium salt, used as a potassium salt or magnesium salt, among these, sulfonate and carboxylate is particularly preferred. The amount of the anionic group in the polyurethane resin is preferably in the range of 0.05 to 8% by weight. When the amount of the anionic group is small, the water solubility or water dispersibility of the polyurethane resin tends to be poor, and when the amount of the anionic group is large, the water resistance of the coating layer after coating is poor,
In some cases, moisture is absorbed and the films are easily fixed to each other.

The final dry coating layer thickness of the laminated film of the present invention is preferably from 0.003 to 2 μm, more preferably from 0.01 to 1 μm, and particularly preferably from 0.03 to 1 μm.
The range is 0.2 μm. When the thickness of the coating layer is more than 2 μm, the films are likely to adhere to each other,
In particular, when the coated film is re-stretched for the purpose of increasing the strength of the film, the film may be easily adhered to the roll during the process. On the other hand, if the thickness of the coating layer is 0.0
If it is less than 03μm, it may not be possible to Ru obtain a uniform coating.

In the coating solution for obtaining the coating layer in the present invention, a methylol compound is used as a crosslinking agent in order to improve the fixability (blocking property), water resistance, solvent resistance and mechanical strength of the coating layer. Alternatively, alkylated urea-based, melamine-based, guanamine-based, acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compounds, block polyisocyanates, silane coupling agents, titanium coupling agents, zirco-alumines -A coupling agent, a peroxide, a heat or photoreactive vinyl compound, a photosensitive resin, or the like. Further, if necessary, it may contain an antifoaming agent, a coating improver, a thickener, an antistatic agent, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment and the like.

The above coating solution was applied to polyethylene-2,6-
As a method of applying to a naphthalate film, "Coating method", published by Yuji Harasaki, Maki Shoten, 1979
Using a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or any other coater shown in (1) above to apply it to a film that has already been biaxially stretched. And may be applied in a biaxially stretched film manufacturing process. As a method of applying in a biaxially stretched film manufacturing process, a polyethylene-2,6-naphthalate film stretched uniaxially in the longitudinal direction is applied, and in a dried or undried state, a direction perpendicular to the further uniaxially stretched direction. The method of performing heat treatment after stretching the film has a great advantage in view of the production cost since film formation and coating and drying can be performed at the same time, and is particularly preferably employed, but is not limited thereto.

The stretching step for obtaining the above-mentioned film comprises:
Preferably, the stretching is performed at 120 to 180 ° C, and the stretching ratio is at least 4 times or more, preferably 6 to 20 times, in area ratio. The stretched film is heat-treated at 150 to 250 ° C., and is further relaxed by 0.1 to 20% in the machine direction and / or the cooling zone at the heat treatment outlet in the machine direction and the transverse direction. Is preferred. In particular, 12
The coating solution is applied to a uniaxially stretched polyethylene-2,6-naphthalate film stretched 2 to 6 times in the longitudinal direction of the film by a roll stretching method at 0 to 180 ° C., and subjected to appropriate drying or drying. The polyethylene-2,6-naphthalate uniaxially stretched film was immediately stretched 2 to 6 times at 120 to 180 ° C. in the direction perpendicular to the previous stretching direction, and 1.01 to 1201 ° C. in the longitudinal direction of the film. A method in which the film is re-stretched to 1.9 times and heat-treated at 150 to 250 ° C for 1 to 600 seconds is preferable. Before the heat treatment, it is also preferable to increase the strength in the transverse direction by re-stretching the film in a direction perpendicular to the longitudinal direction of the film at 120 to 230 ° C. by 1.01 to 1.9 times.
According to this method, the coating layer can be dried at the same time as the stretching, and the thickness of the coating layer can be reduced according to the stretching ratio. Thus, a film suitable as a polyethylene-2,6-naphthalate film substrate Can be manufactured relatively inexpensively.

The coating liquid in the present invention is polyethylene-
It may be applied to only one side of the 2,6-naphthalate film or may be applied to both sides. When applied to only one side, a coating layer using a coating solution other than the coating liquid of the present invention is formed on the opposite side as necessary, and the polyethylene-2,6-naphthalate film of the present invention has other properties. It can also be provided. Note that the film may be subjected to a chemical treatment or a discharge treatment before application in order to improve the coating property and adhesion of the coating agent to the film. Further, in order to improve the surface characteristics of the coating layer of the biaxially stretched polyethylene-2,6-naphthalate film of the present invention, the coating layer may be subjected to a discharge treatment after the formation of the coating layer.

The strength F5 at 5% elongation in the longitudinal direction of the film of the present invention is 1.5 × 10 ⁸ Pa or more, the Young's modulus in the longitudinal direction is 5.9 × 10 ⁹ Pa or more, and the Young's modulus in the transverse direction is Is 5.9 × 10 ⁹ Pa or more. With a film that does not satisfy such strength, it is difficult to achieve thinning. That is, when tension is applied during use, the elongation of the film is undesirably increased. In particular, when used as a base film of a magnetic recording medium, large elongation is not preferable because distortion of a screen called skew occurs and sound quality deteriorates. The term “thinning” as used in the present invention means that the thickness of the base film is 9 μm or less, preferably 7 μm or less, more preferably 5 μm or less.

The density of the polyethylene-2,6-naphthalate film is usually at least 1.360 g / cm 3, preferably at least 1.370 g / cm 3. If the density is low, the dimensional stability of the film may be deteriorated. In order to maintain the dimensional stability of the film, the shrinkage at 150 ° C. for 30 minutes in both the vertical and horizontal directions is preferably 5% or less, preferably 3% or less, more preferably 2% or less. Can be achieved by relaxation at the time of heat setting. The center line average roughness (Ra) of the surface of the coating layer formed as described above is usually 0.020 μm or less, preferably 0.002 to 0.020 μm, and more preferably 0.003 to 0.1 μm. 015 μm, particularly preferably in the range of 0.003 to 0.010 μm. Ra is 0.
If it is less than 002 μm, the slipperiness tends to be insufficient and the workability tends to deteriorate. On the other hand, when Ra exceeds 0.020 μm, when used as a base film of a magnetic recording medium, magnetic conversion characteristics such as S / N ratio may be deteriorated, and dropout may increase.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In addition, the measuring method and definition of various physical properties and characteristics in the present invention are as follows. In Examples and Comparative Examples,
"" Means "parts by weight". (1) Tensile strength (F5 value) Tensile tester Intesco Model 20 manufactured by Intesco Corporation
Using a type 01, a sample film having a length of 50 mm and a width of 15 mm was pulled at a speed of 50 mm / min in a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH, and the strength at 5% elongation was defined as F5 value. .

(2) Young's modulus Tensile tester Intesco Model 200 manufactured by Intesco Corporation
A sample film having a length of 300 mm and a width of 20 mm was pulled at a strain rate of 10% / min in a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH using a mold 1, and the first linear part of the tensile stress-strain curve was obtained. And is calculated by the following equation. E = Δσ / Δε (where E is Young's modulus (Pa), and Δσ is 2
The stress difference due to the original average cross-sectional area between points, Δε is the strain difference between the same two points)

(3) Center line average surface roughness (Ra) The center line average surface roughness was determined as follows using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Co., Ltd. That is, a reference length L (2.55 mm) from the film cross-section curve in the direction of its center line.
, And the center line of the extracted part is the x-axis,
When the roughness curve was represented by y = f (x) using the direction of the vertical magnification as the y-axis, ten values given by the following equations were measured, and the average value was defined as Ra. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

[Number 1] Ra = (1 / L) ∫ 0 L | f (x) | dx

(4) Sticking property The sticking property (blocking property) was tested by ASTM-D-18 using a film kept in a thermo-hygrostat at 40 ° C., 80% RH and 10 kgf / cm 2 for 20 hours.
The peel strength was measured by the method of No. 93. (5) Sliding property (F / F μd) On a smooth glass plate, two films cut to a width of 15 mm and a length of 150 mm are stacked, and a rubber plate is placed thereon, and a load is further placed thereon. With the contact pressure between the two films being 2 g / cm2, the films were slid at 20 mm / min to measure the frictional force. The coefficient of friction at the point of sliding by 5 mm was defined as the dynamic friction coefficient (F / F μd).

(6) Abrasion resistance While contacting the film with the hard chrome fixing pin,
After running for 00 m, abrasion white powder adhering to the hard chrome fixing pin was visually observed, and evaluated by the following three grades of ○, Δ, and ×. The film speed was 13 m / min, the tension was about 200 g, and the angle at which the film was sown on the pin was 135.
°. ：: No white powder generated △: Small white powder generated ×: Large white powder generated

(7) Magnetic Tape Characteristics (Characteristics of Magnetic Recording Medium) First, the following magnetic paint was applied to a film, and a magnetic layer was formed so that the film thickness after drying was 5 μm. That is,
200 parts of magnetic fine powder, 30 parts of polyurethane resin, 10 parts of nitrocellulose, 10 parts of polyvinyl chloride copolymer, lecithin 5
, 100 parts of cyclohexanone and 300 parts of methyl ethyl ketone were mixed and dispersed in a ball mill for 48 hours, and then 5 parts of a polyisocyanate compound was added to form a magnetic paint. After this was applied to a film, it was magnetically oriented before the paint was sufficiently dried and solidified. And then dried. Further, this coated film is subjected to a surface treatment with a super calender, and
Video tape was slit to inch width. This video tape was evaluated for the following magnetic tape characteristics at normal speed using an NV-3700 type video deck manufactured by Matsushita Electric Corporation.

(A) VTR head output The VTR head output at a measuring frequency of 4 MHz was measured with a synchroscope, the reference tape was set to 0.0 decibel (dB), and the relative value was determined based on the following criteria. . ：: +2 dB or more Δ: +0 dB to +2 dB ×: +0 dB or less (B) Skew A video tape on which a chroma video signal is recorded is played back.
Perform a delayed sweep operation on the Shiva-Soku Color Monitor CMM20-11, read the amount of distortion on the screen with a measure, convert it to one horizontal scanning time using the ratio of the entire width of the monitor screen, and convert the value expressed in μsec to the following standard. Judged. ：: 2 μsec or less Δ: 2 μsec to 5 μsec ×: 5 μsec or more

(8) Adhesive Strength of Magnetic Layer The adhesive strength of the magnetic layer was determined by measuring the above-mentioned video tape with a double-sided tape No. manufactured by Scotch Corporation. 665, using a tensile tester Intesco Model 2001 manufactured by Intesco Corporation,
In a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH, 180 ° peeling was performed at a speed of 500 mm / min, and the applied load was measured. (9) Carboxyl value Pohl's method (Anal. Chem., 26, 161)
4 (1954)). (10) Contact angle of water droplet The contact angle was determined by a droplet method using a contact angle meter CA-DA type manufactured by Kyowa Interface Science. The water used was Millipore's MILLI-Q REAGENT-WATER-S
Pure water purified by a YSTEM device was used. The time from the dropping of the droplet to the measurement was about 30 seconds, the measurement was performed six times, and the average value was adopted.

Example 1 (Production of polyethylene naphthalate)
100 parts of dimethyl 6-dicarboxylate, 60 parts of ethylene glycol and 0.1 part of calcium acetate monohydrate were placed in a reactor, and a transesterification reaction was performed. That is, the reaction start temperature was set to 180 ° C., and the reaction temperature was gradually increased with the distillation of methanol. After 4 hours, the temperature was raised to 230 ° C. to substantially end the transesterification reaction. Next, 0.04 part of phosphoric acid was added, and 0.04 part of antimony trioxide was added.
And 0.2 parts of 0.5 μm silica particles were added, and a polycondensation reaction was carried out by a conventional method. That is, the temperature was gradually increased and the pressure was gradually decreased. After 2 hours, the temperature was 290 ° C. and the pressure was 0.3 mmHg. 4 after the start of the reaction
After a lapse of time, the reaction was stopped, and polyethylene naphthalate was discharged under nitrogen pressure. The molten polymer was directly connected to an extruder as it was, filtered with a filter, and then extracted in a strand shape and cut into chips to obtain a polymer raw material. The resulting polyethylene naphthalate polymer raw material had an intrinsic viscosity of 0.68 and a carboxyl group value of 80 equivalents / ton.

(Production of polyethylene naphthalate film) Next, the obtained polyethylene naphthalate raw material was dried,
The sheet was extruded at 300 ° C. from an extruder into an amorphous sheet using an electrostatic application cooling method. The obtained amorphous sheet was first stretched 3.0 times at 135 ° C. in the machine direction. Subsequently, a water-soluble polyester comprising 92 mol% of terephthalic acid, 8 mol% of sodium sulfoisophthalic acid, 75 mol% of ethylene glycol and 25 mol% of diethylene glycol (details)
The details are as follows) 95 parts and polyolefin wax as lubricant (San Nopco Nopcoat PEM-17)
An aqueous coating agent consisting of 5 parts and 1900 parts of water was applied to one surface, stretched 4.0 times in the transverse direction at 140 ° C.
The film is stretched 1.8 times again at 60 ° C., then stretched 1.3 times at 220 ° C. in the transverse direction, heat-set at 230 ° C. while stretching, and relaxed 4% in the longitudinal and transverse directions upon cooling. And the thickness of the coating layer is 0.06 μm and the film thickness is 4.5 μm.
m, F5 value 2.1 × 10 ⁸ Pa, Young's modulus in vertical direction
1 × 10 ⁹ Pa, Young's modulus in the horizontal direction 7.6 × 10 ⁹ P
a, density 1.375 g / cm ³ , Ra 0.
A 008 μm biaxially stretched polyethylene-2,6-naphthalate film was obtained. The properties of the obtained film are as shown in Table 1, and the film was excellent in process stability. When this film was used as a VTR tape, the VTR head output and the skew characteristics were both good. ・ 80 parts of water-soluble polyester dimethyl terephthalate, 5-sodium sulfoiso
10 parts of dimethyl phthalate, 50 parts of ethylene glycol,
10 parts of diethylene glycol and 0.1 of calcium acetate
Parts, lithium acetate 0.3 parts, antimony trioxide 0.03
And transesterification according to the usual method.
0.05 parts of trimethyl acid were added. Then gradually rise
Reduce the temperature and pressure and finally compress at 280 ° C and 1mmHg or less.
The combined reaction was performed to obtain a water-dispersible polyester. Got
The composition of the polyester was measured by H-NMR.
As an acidic component, 92 mol% of terephthalic acid, 5-sodium
8 mol% of sulphoisophthalic acid, as a glycol component
75% by mole of ethylene glycol, diethylene glycol
Was 25 mol%.

Example 2 Same as Example 1 except that 90 parts of a water-soluble polyester, 5 parts of a water-soluble polyalkylene glycol (PAG) modified silicon (Toshiba Silicon YF3842) as a lubricant, and 5 parts of 0.1 μm silica particles were used. To obtain a film. The properties of the obtained film are as shown in Table 1, and showed excellent adhesiveness and excellent process stability.

Example 3 In place of the water-soluble polyester of Example 1, Dainippon
Hydran manufactured by Ki Kagaku Kogyo Co., Ltd. (94 parts of polyester having 60 mol% of terephthalic acid and 40 mol% of isophthalic acid in the dicarboxylic acid component, 61 mol% of ethylene glycol in the glycol component, and 39 mol% of diethylene glycol) It consists of 90 parts of a carboxyl group-modified polyester which is a reaction product composed of 6 parts of 2,2-dimethylolpropionic acid and 10 parts of isophorone diisocyanate.
A film was obtained in the same manner as in Example 1 except that water-soluble polyurethane) was used. The properties of the obtained film are as shown in Table 1, and showed excellent adhesiveness and excellent process stability.

Example 4 A water-soluble polyacrylate ( 51 parts of ethyl acrylate , methacrylic acid ) was used in place of the water-soluble polyester of Example 1.
40 parts of methyl and 9 parts of methacrylic acid in 400 parts of distilled water
Into a polymerization initiator while heating and expanding to about 60 ° C.
Emulsion polymerization by adding potassium sulphate
Ammonia water to the aqueous polyacrylate
A film was obtained in the same manner as in Example 1 except that a polyacrylate emulsion adjusted to H7.5 was used. The properties of the obtained film are as shown in Table 1, and showed excellent adhesiveness and excellent process stability.

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that no coating layer was provided. The properties of the obtained film are as shown in Table 1. Many contact flaws were generated on the film surface with the transport roll, and the film was not usable for magnetic recording. Comparative Example 2 A film was obtained in the same manner as in Example 4, except that 100 parts of the water-soluble polyacrylate was used without adding a lubricant. The properties of the obtained film are as shown in Table 1. The film had to be cleaned every 5 to 8 hours due to abrasion powder attached to the re-stretching roll, and the film was extremely poor in production efficiency.

Comparative Example 3 A film was obtained in the same manner as in Example 5 except that the amount of the lubricant was 30 parts and the amount of the water-soluble polyacrylate was 70 parts. The properties of the obtained film are as shown in Table 1. Although there was no problem in re-stretching, the amount of blooming of the lubricant was extraordinarily large, and the adhesion to the magnetic layer was poor. Comparative Example 4 A water-soluble polyester was added in an amount of 0.2 part by weight of a lubricant.
A film was obtained in the same manner as in Example 1 except that the amount was changed to 00 parts. The properties of the obtained film are as shown in Table 1. Adhesive breakage to the redraw roll frequently occurred, and stable production of the product was impossible.

Comparative Example 5 A polyethylene terephthalate raw material obtained according to a conventional method was dried and extruded at 290 ° C. from an extruder into a sheet.
An amorphous sheet was formed using an electrostatic application cooling method. The obtained amorphous sheet was stretched in the machine direction by 4.5 times at 90 ° C., followed by 92 mol% of terephthalic acid, 8 mol% of sodium sulfoisophthalic acid, 75 mol% of ethylene glycol and 25 mol% of diethylene glycol. An aqueous coating agent consisting of 95 parts of polyester, 5 parts of polyolefin wax (San Nopco's Nopcoat PEM-17) and 1900 parts of water as a lubricant was applied on one side, and then 100 ° C. in the lateral direction.
And stretched 3.8 times. Further, the film was stretched 1.3 times again at 130 ° C., and then stretched 1.1 times at 190 ° C. in the transverse direction.
Heat set at 230 ° C while stretching, relax 4% in the vertical and horizontal directions during cooling, apply coating layer thickness 0.06μ
m, film thickness 4.5 μm, F5 value 1.4 × 10 ⁸ P
to give a, longitudinal Young's modulus 6.3 × 10 ⁹ Pa, a biaxially stretched polyethylene terephthalate film in the transverse direction Young's modulus 6.3 × 10 ⁹ Pa. The characteristics of the obtained film are as shown in Table 1, and the film was poor in skew characteristics and could not be put to practical use.

[0049]

[Table 1] (The abbreviations in the table are as follows: PES: polyester, PAc: polyacrylate, PU: polyurethane, PE: polyethylene)

[0050]

Industrial Applicability The film of the present invention has excellent adhesiveness and mechanical strength, is excellent in stable productivity, and has high industrial value.

Claims (1)

(57) [Claims] 1. A polyethylene-2,6-naphthalate film having a thickness of not more than 9 .mu.
A laminated film having a coating layer comprising at least one resin selected from the group consisting of aqueous polyester, aqueous polyacrylate and aqueous polyurethane, containing a lubricant by weight, and simultaneously satisfying the following formulas: Laminated film. F5 value in film longitudinal direction ≧ 1.5 × 10 ⁸ Pa ... Young's modulus in film longitudinal direction ≧ 5.9 × 10 ⁹ Pa… Young's modulus in film lateral direction ≧ 5.9 × 10 ⁹ Pa… 70 ° ≦ coating layer Water droplet contact angle ≤ 85 ° on the surface ...