JP3684095B2 - Slippery composite polyester film - Google Patents

Description

【００７１】
表１から明らかなように、本発明による易滑性複合ポリエステルフイルムは摩擦係数が低く、フイルム間のブロッキングがなく、また耐削れ性に優れて蒸着時の熱負けもない。これに対し、本発明の要件を満たさないものはこれら特性を同時に満足することができない。
【００７２】
【発明の効果】
本発明によれば、表面平坦性、製膜・加工時の易滑性、耐ブロッキング性、耐削れ性に優れ、種々の用途、中でも高密度磁気記録媒体のベースフイルムとして有用な複合ポリエステルフイルムを提供することができる。
【図面の簡単な説明】
【図１】連続皮膜層の微細網目凹凸構造を模式的に示した図である。
【図２】連続巻取り式蒸着装置の概略構成図である。
【符号の説明】
１：真空室
２：冷却キャン
３：蒸着源
４：フイルム供給ロール
６：蒸着材料
７：フイルム巻取りロール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a slippery composite polyester film. More specifically, it is excellent in flatness, slipperiness during film formation / processing, blocking resistance, abrasion resistance, magnetic recording medium, various photographic materials, packaging materials, electrical insulation. The present invention relates to a base film used for materials, general industrial materials and the like, and more particularly to a slippery composite polyester film suitable as a base film for a ferromagnetic metal thin film type magnetic recording medium.
[0002]
[Prior art]
Biaxially stretched polyester film, represented by polyethylene terephthalate film, has excellent mechanical properties, heat resistance, chemical resistance, etc., so audio tape, video tape, computer tape, floppy disk, video floppy, photo film, packaging As a material such as a film for a film, a metallizing film for a capacitor, an electrical insulating film, or an OHP film, the demand has recently been particularly remarkable.
[0003]
However, in order to smoothly produce the film and apply it to the above-mentioned uses, it is inevitable to improve the slipperiness of the film.
[0004]
For example, in the case of a film with a particularly flat surface, the slipping property of the film is insufficient, which causes serious troubles in operations such as winding, rewinding, coating, and slitting. Cause trouble. For example, when various molded products manufactured by subjecting an unstretched or uniaxially stretched film of polyethylene terephthalate to pressure molding or vacuum molding are overlapped, the molded products are mutually attached if the surface lubricity is insufficient. Accordingly, the flow workability in the machining process is significantly reduced.
[0005]
Conventionally, as means for improving the slipperiness of a polyester film, for example, a film is formed using polyester added with fine particles of various fillers such as silicon oxide, kaolin, talc, calcium carbonate or alumina, and then in a biaxial stretching process. When the film thickness is reduced, it has been put into practical use that a phenomenon in which a filler protrudes as a fine protrusion on the film surface. Similarly, as a technique for improving slipperiness using microprojections, a method of converting a catalyst used during polymerization of polyester into particles insoluble in the polymer is also known.
[0006]
Although these methods have been successful in improving the slipperiness of the film, the presence of fine particles in the film composition naturally reduces the transparency of the film, Large particle size particles mixed in a minute proportion in fine particles can cause coarse protrusions on the film surface, that is, F / S, frequently generate D / O of video tape, or generate voids in the film composition. There are still problems to be improved. In particular, diazo film, metalizing film, photographic film, or polyester film as a material such as magnetic tape or floppy disk that requires surface flattening by densification, decrease in transparency or formation of voids and coarse protrusions Is a serious obstacle.
[0007]
As another means for improving slipperiness, a method is known in which a coating film containing fine particles is provided on at least one surface of a film, and fine protrusions are formed on the film. This method has a problem that even if the slipperiness can be secured, the adhesion of the polyester film is not sufficient and the abrasion resistance is poor.
[0008]
In particular, as a base film of an extremely high density magnetic recording medium, particularly a magnetic recording medium having a magnetic layer made of a ferromagnetic metal thin film, there is a contradiction between ultra-flatness for high output and easy slipping for film winding. However, with respect to the slipperiness, a method of providing a film that imparts slipperiness on the side of the tape on which the backcoat layer is provided is known. However, even though the conventional film can ensure the slipperiness, there is a problem of so-called heat loss phenomenon that the film melts by the heat of the metal particles when the metal thin film is provided by vapor deposition.
[0009]
[Problems to be solved by the invention]
The object of the present invention is to eliminate such problems, excellent flatness, slipperiness during film formation and processing, blocking resistance, abrasion resistance, magnetic recording media, various photographic materials, packaging materials, electrical insulating materials, It is an object of the present invention to provide a slippery composite polyester film suitable as a base film used for general industrial materials and the like, particularly as a base film for a ferromagnetic metal thin film type magnetic recording medium.
[0010]
[Means for Solving the Problems]
  An object of the present invention is, according to the present invention, a composite polyester film in which a continuous film layer having a fine network uneven structure is provided on at least one side of a polyester film,,It has inert fine particles having an average particle diameter of 10 to 200 nm, and Ra (root mean square roughness) by an AFM (atomic force microscope) of the outer surface of the coating layer is 3 to 20 nm.The area ratio of the convex part / concave part is 0.2-5, and the frequency of projections by the inert fine particles present in the concave part is 10 ^Four -10 ⁸ Piece / mm ² And concaveThis is achieved by an easy-slip composite polyester film characterized in that the height of the protrusions due to the fine particles present in the part is 0.3 to 3 times the height of the convex part of the coating layer.
[0011]
The present invention is described in detail below.
Preferred examples of the polyester constituting the polyester film of the present invention include polyethylene terephthalate, polyethylene isophthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and the like. can do. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are particularly preferred.
[0012]
The polyester may be a homopolyester or a copolyester. In the case of copolyester, the copolymerization component of polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate includes, for example, diethylene glycol, propylene glycol, neopentyl glycol, polyoxyethylene glycol, p-xylene glycol, 1,4-cyclohexane. Diol components such as dimethanol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (for polyethylene-2,6-naphthalenedicarboxylate), 2,6-naphthalenedicarboxylic acid (for polyethylene terephthalate) ) Other dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid. In addition, it is preferable that the quantity of a copolymerization component shall be 20 mol% or less with respect to all the acid components, and also 10 mol% or less.
[0013]
Furthermore, trifunctional or more polyfunctional compounds such as trimellitic acid and pyromellitic acid can be copolymerized. In this case, it is preferable to copolymerize the polymer in a substantially linear amount, for example, 2 mol% or less.
[0014]
The thickness of the polyester film in the present invention is preferably 1 to 20 μm, more preferably 2 to 10 μm.
[0015]
The polyester film in the present invention may or may not contain inert particles. In the case of inclusion, organic particles or inorganic particles may be used.
[0016]
In such inert particles, organic particles include polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, methyl methacrylate copolymer cross-linked product, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resin. Preferred examples include particles composed of polymers such as the above, and core-shell structured particles composed of graft copolymers containing these polymers as components, and examples of inorganic particles include silica, alumina, titanium dioxide, feldspar, kaolin, talc, graphite. Preferred examples include particles made of inorganic compounds such as calcium carbonate, molybdenum disulfide, carbon black, and barium sulfate.
[0017]
These particles are usually used as a reaction system, preferably as a slurry in glycol, at any time during the production of polyester, for example during transesterification or polycondensation reaction by transesterification, or by direct polymerization. Add in. The average particle size of the inert particles is preferably 0.005 to 2 μm, more preferably 0.01 to 1.8 μm, and the addition amount is 0.001 to 2% by weight, more preferably 0.01 to 1.5 μm. It is preferable that it is weight%.
[0018]
The polyester film in the present invention preferably has an AFM Ra (root mean square roughness) of 0.1 to 5 nm, more preferably 0.3 to 4 nm. The polyester film may be a single-layer film or a multilayer film composed of two or more layers, each of which has a different composition.
[0019]
The continuous film layer having a fine network uneven structure in the present invention is preferably composed of a layer containing a binder resin, inert fine particles and a surfactant.
[0020]
Examples of the binder resin constituting the continuous film in the present invention include alkyd resins, phenol resins, epoxy resins, amino resins, polyurethane resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, and the like. . From the viewpoint of adhesion to the polyester film, protrusion retention, slipperiness, etc., water-soluble or water-dispersible polyester resins, acrylic resins and acrylic-polyester resins are preferred. These resins may be a single polymer or a copolymer, and may be a mixture.
[0021]
Examples of the acid component constituting the water-soluble or water-dispersible polyester resin include terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-diphenyl. Dicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, 5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid Examples thereof include polyvalent carboxylic acids such as acid and trimellitic acid monopotassium salt.
[0022]
Examples of the hydroxy compound component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p- Xylylene glycol, ethylene oxide adduct of bisphenol A, diethylene glycol, triethylene glycol, polyethylene oxide glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropanoate And the like. A polyester resin can be produced from these compounds by a conventional method. From the viewpoint of producing an aqueous coating material, it is preferable to use an aqueous polyester resin containing a 5-sodium sulfoisophthalic acid component or a carboxylate group. Such a polyester resin can be a self-crosslinking type having a functional group in the molecule, or can be crosslinked using a curing agent such as a melamine resin or an epoxy resin.
[0023]
Examples of the acrylic component used in the production of the water-soluble or water-dispersible acrylic resin include acrylic acid esters (the alcohol residues include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group). Group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.); methacrylate ester (alcohol residue is the same as above); 2-hydroxyethyl acrylate, 2 -Hydroxy-containing monomers such as hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate; acrylamide, methacrylamide, N-methyl methacrylamide, N-methyl acrylamide, N-methylol acrylamide, N- Amide group-containing monomers such as tyrolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide; N, N-diethylaminoethyl acrylate, N, N-diethylamino Examples include amino group-containing monomers such as ethyl methacrylate. These monomers include monomers containing sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (for example, sodium salt, potassium salt, ammonium salt, etc.) or salts thereof; crotonic acid, itaconic acid, acrylic acid, Monomer containing a carboxyl group such as maleic acid, fumaric acid, and salts thereof (for example, sodium salt, potassium salt, ammonium salt, etc.) or a salt thereof; monomer containing anhydride such as maleic anhydride, itaconic anhydride, etc. Other vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid mono ester, acrylonitrile, methacrylonitrile, alkyl itaconic acid mono Ester, vinylidene chloride, vinyl acetate, may be used vinyl chloride, and monomers such as allyl glycidyl ether combination. In this case, it is preferable that components of (meth) acrylic monomers such as acrylic acid derivatives and methacrylic acid derivatives are contained in an amount of 50 mol% or more, and it is particularly preferable that a component of methyl methacrylate is contained.
[0024]
The water-soluble or water-dispersible acrylic resin can be self-crosslinked with a functional group in the molecule, or can be crosslinked using a crosslinking agent such as a melamine resin or an epoxy compound.
[0025]
In the present invention, the water-soluble or water-dispersible acrylic-polyester resin is used to include an acrylic-modified polyester resin and a polyester-modified acrylic resin, and the acrylic resin component and the polyester resin component are bonded to each other. For example, a graft type, a block type, etc. are included. Acrylic-polyester resin, for example, adds a radical initiator to both ends of the polyester resin to polymerize the acrylic monomer, or adds a radical initiator to the side chain of the polyester resin to polymerize the acrylic monomer. Or by adding a hydroxyl group to the side chain of the acrylic resin and reacting with a polyester having an isocyanate group or a carboxyl group at the terminal to form a comb polymer.
[0026]
Examples of the component constituting the acrylic-polyester resin include the compounds exemplified as the component constituting the acrylic resin and the polyester resin.
[0027]
The content in the continuous film of at least one resin selected from the group consisting of a water-soluble or water-dispersible polyester resin, acrylic resin and acrylic-polyester resin in the present invention is preferably 20 to 80% by weight. If it is less than 20% by weight, the adhesion to the film is lowered, whereas if it exceeds 80% by weight, other components (inert fine particles, surfactants, etc.) are insufficient, and the overall properties cannot be satisfied.
[0028]
As shown in FIG. 1, the continuous film layer having a fine mesh concavo-convex structure in the present invention is a continuous film having a surface shape of a mesh and having inert fine particles in the mesh part.
[0029]
As a means for making the surface of the continuous film layer into a fine mesh concavo-convex structure, a resin having poor spreadability (stretchability) such as polyvinyl alcohol, gelatin, cellulose, sulfonate group-containing styrene copolymer is used as a part of the binder resin. The method used is preferably applicable. The content of these poorly spreadable resins in the continuous film is preferably 5 to 50% by weight, more preferably 10 to 40% by weight. If this amount is less than 5% by weight, the continuous film does not have a sufficient fine network structure, so that the slipperiness is insufficient. On the other hand, if it exceeds 50% by weight, the abrasion resistance of the continuous film itself is reduced. It is not preferable.
[0030]
As the material of the inert fine particles contained in the continuous film layer, polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, methyl methacrylate copolymer crosslinked product, polytetrafluoroethylene, polyvinylidene fluoride, Any of organic materials such as polyacrylonitrile and benzoguanamine resin, and inorganic materials such as silica, alumina, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black, and barium sulfate may be used. Further, a core-shell type particle having a multilayer structure composed of substances having different properties on the inside and outside may be used.
[0031]
The average particle diameter of the inert fine particles is preferably 10 to 200 nm, more preferably 20 to 100 nm, and the content of the fine particles in the continuous film layer is preferably 5 to 40% by weight, more preferably 5 to 20% by weight. It is. Further, the particle size of the fine particles is preferably narrowly distributed, and more preferably substantially uniform. When the average particle size is less than 10 nm or the content is less than 5% by weight, the slipping property of the film is insufficient, the winding property and the transportability in the film forming process are insufficient, and blocking is likely to occur. On the other hand, when the average particle diameter exceeds 200 nm or the content exceeds 40% by weight, there arises a problem that the film is easily scraped.
[0032]
The surfactant contained in the continuous film layer in the present invention is not particularly limited, and examples thereof include nonionic surfactants, anionic surfactants, and cationic surfactants. The content of this surfactant is preferably in the range of 5 to 40% by weight.
[0033]
Although the coating layer in the present invention is a continuous coating, Ra (root mean square roughness) by an AFM (atomic force microscope) on the outer surface thereof is 3 to 20 nm, preferably 4 to 15 nm. When this Ra is less than 3 nm, the slipperiness is insufficient, the film winding property and the transportability in the film-forming process are insufficient, and blocking easily occurs. On the other hand, when Ra exceeds 20 nm, the coating layer is easily scraped.
[0034]
In the continuous film layer of the present invention, the height of protrusions due to the inert fine particles present in the concave part of the continuous film is required to be 0.3 to 3 times, preferably 0.5 to 2 times the height of the convex part of the continuous film layer. There is. If this height is less than 0.3 degrees, blocking is likely to occur, while if it exceeds 3 times, scraping tends to occur.
[0035]
In addition, the area ratio of the convex portion / concave portion of the continuous film layer is preferably 0.2 to 5, more preferably 0.3 to 3, and particularly preferably 0.5 to 2. When this ratio is less than 0.2, the friction coefficient becomes high and the slipperiness becomes insufficient. On the other hand, when it exceeds 5, it becomes easy to cause blocking.
[0036]
The frequency of protrusions due to the inert fine particles present in the concave portions of the continuous film layer is 1 × 10^Four~ 1x10⁸Piece / mm²It is preferable that This frequency is 1 × 10^FourPiece / mm²If it is less than 1, the slipperiness is insufficient, whereas 1 × 10⁸Piece / mm²If it exceeds, it will be easy to cut.
[0037]
In addition to the binder resin, the inert fine particles, and the surfactant, other components may be added to the continuous film layer in the present invention as long as they do not affect the present invention. For example, in order to further improve the blocking resistance, a method of adding a silicone wax or a siloxane copolymer is preferably used.
[0038]
1-100 nm is preferable and, as for the thickness of the continuous film layer in this invention, More preferably, it is 3-30 nm.
[0039]
The composite polyester film of the present invention can be produced according to a conventionally known method.
[0040]
For example, when the polyester film is a single layer, the polyester is extruded into a film shape from the base at a melting point of Tm ° C. to (Tm + 70) ° C., and then rapidly cooled and solidified at 40 to 90 ° C. to obtain an unstretched film. Thereafter, the unstretched film is uniaxially (longitudinal or transverse) uniaxially (longitudinal or transverse) at a temperature of (Tg-10) to (Tg + 70) ° C. (where Tg is the glass transition temperature of the polyester). The film is stretched at a magnification of 0.0, preferably 3.0 to 7.5, and then a coating solution for forming a film is applied to at least one surface of the film, and then Tg to a direction perpendicular to the above direction. The film is stretched at a temperature of (Tg + 70) ° C. at a magnification of 2.5 to 8.0 times, preferably a magnification of 3.0 to 7.5 times. Further, if necessary, the film may be stretched again in the longitudinal direction and / or the transverse direction.
[0041]
That is, it is preferable to perform stretching in two, three, four or even more stages. The total draw ratio is usually 9 times or more, preferably 12 to 35 times, more preferably 15 to 32 times as the area draw ratio. Subsequently, excellent dimensional stability is imparted by thermally fixing and crystallizing the biaxially oriented film at a temperature of (Tg + 70) to (Tm-10) ° C., for example, 180 to 250 ° C. The heat setting time is preferably 1 to 60 seconds.
[0042]
The composite polyester film of the present invention is used in various fields, and is particularly useful as a base film for high-density magnetic recording media, particularly ferromagnetic metal thin film type magnetic recording media.
[0043]
The composite polyester film of the present invention is formed on the surface opposite to the surface on which the continuous film layer is formed by a method such as vacuum deposition, sputtering, ion plating, etc. And a protective layer such as diamond-like carbon (DLC) and a fluorine-containing carboxylic acid-based lubricating layer are sequentially provided on the surface of the ferromagnetic metal thin film layer. By providing a known backcoat layer on the surface of the film, it is excellent in electromagnetic conversion characteristics such as output in the short wavelength region, S / N, C / N, etc., and has low dropout and error rate. It can be a medium. This vapor deposition type electromagnetic recording medium can be used as Hi8 for analog signal recording, digital video cassette recorder (DVC) for digital signal recording, data 8 mm, tape medium for DDSIV, and is extremely useful.
[0044]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. The measuring method used in the present invention is as follows.
[0045]
(1) Average particle size of fine particles
Measure using light scattering method. That is, the “equivalent sphere diameter” of a particle at a point of 50% by weight of the total particle determined by NICOM MODEL 270 SUBMICRON PARTIC SIZER manufactured by Nicom Instruments Inc. is displayed.
[0046]
(2) Surface roughness by AFM (Atomic Force Microscope)
Using an atomic force microscope Nano ScopeIII AFM J scanner manufactured by Digital Instruments, Ra (22th power average roughness) measured under the following conditions is measured under the following conditions, and an average value of n = 10 is used. .
Probe; single bond silicon sensor
Scanning mode: Tapping mode
Scanning range: 10 μm × 10 μm
Number of pixels: 256 x 256 data points
Scanning speed: 2.0Hz
Measurement environment: room temperature, air
[0047]
(3) Area ratio of convex part / concave part of continuous film layer
From the 10 μm × 10 μm AFM image measured in (2), the ratio of the convex part / concave part is calculated by an image analysis method. An average value of n = 10 is used.
[0048]
(4) Projection height due to inert fine particles present in the recesses of the continuous coating layer
From the 10 μm × 10 μm AFM image measured in (2), the height of 10 protrusions is randomly measured for each image, and the average of the total of 100 AFM images is calculated as the height of the protrusions ( nm).
[0049]
(5) Height of convex part of continuous film layer
From the 10 μm × 10 μm AFM image measured in (2), the height of 10 continuous film convex portions is randomly measured per image, and the total height of 100 continuous convex portions of 10 AFM images is measured. The height is measured, and the average value of 100 positions in total of 10 AFM images is defined as the height of the convex portion (nm).
[0050]
(6) Frequency of protrusions due to inert particles in the presence of recesses in the continuous coating layer
The number of protrusions present in the recesses is counted from the 10 μm × 10 μm AFM image measured in (2), and the frequency is calculated by dividing by the area of the recesses, and the average value of the 10 AFM layers is calculated as the protrusion frequency (number / Mm²).
[0051]
(7) Friction coefficient of film (μs)
Place a fixed glass plate on the lower side of the two overlapped films, take the film on the lower side of the overlapped film (the film in contact with the glass plate) with a low speed roll (about 10 cm / min), A detector is fixed to one end of the upper film (opposite to the take-off direction of the lower film) to detect the starting tensile force between the films. The thread used at that time weighs 1 kg and lower area is 100 cm.²Use one.
[0052]
The friction coefficient (μs) is obtained from the following equation.
μs = Starting tensile force (kg) / Load 1kg
Evaluation is performed according to the following criteria.
○: Less than 0.7
Δ: 0.7 or more and less than 0.80
×: 0.80 or more
[0053]
(8) Blocking resistance
Overlap the processing surface of the two films with the surface to be processed, and add 150kg / cm to this.²Is peeled after 65 hours in an atmosphere of 80% RH at 60 ° C., and the peel strength is evaluated (g number per 5 cm).
In addition, evaluation is performed on the following reference | standard from peeling force.
○: 0 to less than 10 g / cm
Δ: 10 g / cm or less to less than 15 g / cm
X: 15 g / cm or more to tear
[0054]
(9) Scratch resistance
The film was sampled 25 to 30 cm long and 1/2 inch wide, the leather blade was applied to the surface of the coating layer at an angle of 90 ° and a depth of 0.5 mm, a load of 500 g / 0.5 inch, When running at a speed of 6.7 cm / sec, the width in the depth direction of the shavings adhering to the leather is obtained by microscopic photography (× 160 times).
[0055]
The width of the shaving powder in the depth direction is determined as follows. The smaller the width in the depth direction of the shaving powder, the better the shaving property.
○: Less than 3 nm
Δ: 3 nm to less than 5 nm
×: 5 nm or more
[0056]
(10) Heat loss
The presence or absence of heat loss of the composite polyester film is confirmed using a continuous winding vacuum deposition apparatus as shown in FIG.
[0057]
The continuous winding vacuum deposition apparatus is configured for so-called oblique deposition, and the inside is in a vacuum state (for example, about 10^-3In the vacuum chamber 1 defined as Pa), the vapor deposition source 3 for the metal magnetic thin film is rotated counterclockwise (arrow Z direction) in the figure and faces the cooling can 2 cooled to -20 ° C. Is placed.
[0058]
Then, the composite polyester film is fed out from the supply roll 4 rotating in the counterclockwise direction in FIG. 2 in the direction of the arrow D and moved along the peripheral surface of the cooling can 2, and from the vapor deposition source 3 with the electron beam 5. Heated and evaporated vapor deposition material 6 is adhered, a metal magnetic thin film is vapor deposited, and then wound on a winding roll 7. Guide rollers 8 and 9 are disposed between the supply roll 4 and the cooling can 2 and between the cooling can 2 and the take-up roll 7, respectively. A predetermined tension is applied to the composite polyester film running from 2 to the take-up roll 7 so that the composite polyester film runs smoothly.
[0059]
The vapor deposition source 3 is a container 10 in which the above-described metal magnetic material Co—Ni alloy is accommodated, and this vapor deposition source (metal magnetic material) is accelerated by irradiating the electron beam 5 from the electron beam generation source 11 with metal. The magnetic material 6 is heated and evaporated, and this is deposited (evaporated) on the composite polyester film running along the peripheral surface of the cooling can 2 to form a metal magnetic thin film, thereby producing a magnetic recording medium. At this time, an adhesion preventing plate 12 is provided between the vapor deposition source 3 and the cooling can 2, and a shutter 13 is provided so that the position can be adjusted, so that only vapor deposition particles incident on the composite polyester film at a predetermined angle are allowed to pass. . Thus, a metal magnetic thin film is formed by the oblique deposition method.
[0060]
When the surface of the continuous film layer side of the composite polyester film is in contact with the cooling can, and a metal magnetic thin film having a film thickness of 180 nm is formed on the opposite film surface on which the continuous film is formed, evaluation of heat loss is performed according to the following criteria. (The width of the polyester film is 500mm)
○: Heat loss
Δ: Heat loss of 5 mm or more in diameter occurs 3/10 m or more
×: Heat loss of 5 mm or more in diameter occurs 10 pieces / 10 m or more
[0061]
[Example 1]
Polymerization was carried out in a conventional manner by adding dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol, manganese acetate as the transesterification catalyst, antimony trioxide as the polymerization catalyst, and phosphorous acid as the stabilizer. Polyethylene-2,6-naphthalate (PEN) containing no active particles was obtained.
[0062]
This polyethylene-2,6-naphthalate is dried at 170 ° C. for 6 hours and then supplied to an extruder, melted at a melting temperature of 280 to 300 ° C., extruded into a sheet form from a die, and rapidly cooled to an uncoated 82 μm-thickness. A stretched film was obtained.
[0063]
The obtained unstretched film is preheated, further stretched 3.2 times in the machine direction at a film temperature of 95 ° C. between low-speed and high-speed rolls, quenched, and then on one side of the longitudinally stretched film as shown in Table 1. Apply the water-soluble coating liquid having the composition of the continuous film layer, and apply the water-soluble coating liquid of the other film layer on the other side to a thickness of 0.020 μm and 0.009 μm (after stretching and drying), respectively, followed by the stenter And stretched 5.6 times in the transverse direction at 150 ° C. The obtained biaxially stretched film was heat-fixed with hot air at 200 ° C. for 4 seconds to obtain a 4.9 μm thick slippery composite polyester film. Table 1 shows the characteristics of this film.
[0064]
(Composition of other side film)
・ Binder resin
70 parts by weight of acrylic modified polyester SH551A manufactured by Takamatsu Yushi Co., Ltd.
・ Inert particles Acrylic particles (average particle size 40 nm) 10 parts by weight
・ Surfactant Nippon Oil & Fats Co., Ltd. Nonion NS-240 20 parts by weight
[0065]
[Example 3, Comparative Examples 1 and 5]
A slippery composite polyester film was obtained in the same manner as in Example 1 except that the composition of the continuous film layer was changed as shown in Table 1. Table 1 shows the characteristics of this film.
[0066]
[Examples 2 and 4, Comparative Examples 2 to 4]
Polyethylene terephthalate containing dimethyl terephthalate and ethylene glycol, polymerized in a conventional manner by adding manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, and phosphorous acid as a stabilizer, and containing substantially no inert particles (PET) was obtained.
[0067]
This polyethylene terephthalate was dried at 170 ° C. for 3 hours, then supplied to an extruder, melted at a melting temperature of 280 to 300 ° C., extruded into a sheet form from a die, and rapidly cooled to obtain an unstretched film having a thickness of 82 μm. .
[0068]
The obtained unstretched film is preheated, further stretched 3.2 times in the machine direction at a film temperature of 95 ° C. between low-speed and high-speed rolls, quenched, and then on one side of the longitudinally stretched film as shown in Table 1. Apply the water-soluble coating liquid having the composition of the coating layer on the other surface to the thickness of 0.020 μm and 0.009 μm (after stretching and drying), respectively. Then, it was supplied to a stenter and stretched 4.1 times in the transverse direction at 110 ° C. The obtained biaxially stretched film was heat-fixed with hot air at 220 ° C. for 4 seconds to obtain a composite polyester film having a thickness of 6.0 μm. Table 1 shows the characteristics of this film.
[0069]
[Comparative Examples 6 and 7]
A composite polyester film was obtained in the same manner as in Example 2 except that the composition of the continuous film layer and the coating thickness were changed as shown in Table 1. Table 1 shows the characteristics of this film.
[0070]
[Table 1]

[0071]
As apparent from Table 1, the slippery composite polyester film according to the present invention has a low coefficient of friction, no blocking between films, excellent abrasion resistance, and no heat loss during deposition. On the other hand, those that do not satisfy the requirements of the present invention cannot simultaneously satisfy these characteristics.
[0072]
【The invention's effect】
According to the present invention, a composite polyester film excellent in surface flatness, slipperiness during film formation / processing, blocking resistance, abrasion resistance, and useful as a base film for high-density magnetic recording media in various applications. Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a fine network uneven structure of a continuous film layer.
FIG. 2 is a schematic configuration diagram of a continuous winding type vapor deposition apparatus.
[Explanation of symbols]
1: Vacuum chamber
2: Cooling can
3: Deposition source
4: Film supply roll
6: Vapor deposition material
7: Film take-up roll

Claims (6)

On at least one surface of a polyester film, a composite polyester film having a continuous coating layer having a fine mesh concave-said coating layer has a inert fine particles having an average particle diameter of 10 to 200 nm, by AFM of the outer surface Ra (root mean square roughness) is 3 to 20 nm, the area ratio of protrusions / recesses is 0.2-5, and the frequency of protrusions due to inert fine particles present in the recesses is 10 ⁴ to 10 ⁸ / mm ^2. in, and the height of the projection by fine particles present in the recessed portion, lubricity composite polyester film which is a 0.3 to 3 times the convex height of the said coating layer.   The slippery polyester film according to claim 1, wherein the continuous film layer comprises a binder resin, inert fine particles and a surfactant. The easy-slippery according to claim 1 or 2 , wherein the binder resin forming the continuous film layer contains at least one resin selected from the group consisting of water-soluble or water-dispersible polyester resin, acrylic resin and acrylic-polyester resin. Composite polyester film.   The slippery composite polyester film according to claim 1, wherein the polyester film is a film made of polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate.   The back coat layer is provided on the continuous film layer of the composite polyester film according to claim 1 having a continuous film layer having a fine network uneven structure on one side of the film, and the magnetic recording layer is provided on the opposite surface of the film. Magnetic recording medium. 6. The magnetic recording medium according to claim 5 , wherein the magnetic recording layer is a ferromagnetic metal thin film layer.

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