KR100363491B1 - Biaxially Oriented Laminated Polyester Film - Google Patents

Abstract

The biaxially oriented laminated polyester film is composed of a polyester having no crystalline melting peak at 230 ° C. or higher in differential thermal analysis, and has an A layer having a thickness of 2 μm or less laminated on at least one surface of another polyester layer; And a coating layer comprising 50 wt% or more of an acrylic resin or a urethane resin as a coating component and formed on the surface of the A layer.

Description

Biaxially Oriented Laminated Polyester Film

The present invention is a biaxially oriented laminated polyester film; And a base film for metallized film capacitors comprising the sublimation type heat transfer base film or the polyester film.

Polyester films such as polyethylene terephthalate (PET) films and polyethylene naphthalate (PEN) films have excellent mechanical strength, heat resistance, dimensional stability, electrical insulation, chemical resistance and optical properties, which require the film to retain Being almost all the characteristics. In other words, polyester films are used between many general purpose films and industrial plastic films and are high quality films with little defects and high cost performance.

The use of polyester films tends to increase rapidly and diversify. As a result, the polyester film is required to meet the required properties of a wider area. In particular, the adhesion of the film surface is one of the important required properties. For example, when a functional layer such as a deposited metal layer, a magnetic layer, a photosensitive layer, a printing layer, an adhesive layer, a release layer, or the like is formed on the polyester film surface or another polymer layer is laminated thereon, the film surface is such a functional layer. It is required to have sufficient adhesion so that the layer does not peel off easily.

It is common to provide an undercoat on the surface of the polyester film in order to improve the adhesion between the polyester film and the functional layer. The method of providing such an undercoat layer can be roughly classified into the following two types: (i) off-line coating method of coating after film is formed, and (ii) coating in film forming process. An in-line coating method in which the coated film is further stretched. The presence of such an undercoat layer can vary the wettability of the polyester film surface in a wide range depending on the undercoat composition, thereby improving the adhesion of the film surface to various functional layers.

However, when the undercoat is provided according to the adhesion to the functional layer, there may be a problem that the undercoat is easily separated from the polyester film surface at the interface due to the low suitability of the undercoat and the film surface. This problem is increased when the functional layer comprises high hydrophilic polymers such as gelatin, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), cellulose or derivatives thereof.

Products having the functional layer include, for example, photographic films, ink image receiving films, and plating-forming films. Acrylic resins are typical examples of resins having good adhesion to the functional layer.

However, the undercoat of the acrylic resin tends to be easily separated from the polyester film at the interface due to its low compatibility with the polyester film.

Heat transfer recording systems are becoming widespread due to advantageous properties such as clean printing, simple equipment and noiselessness. In particular, the sublimable ink transfer recording system designed primarily for use in copying images, such as video printer images, is superior in flattening compared to the application ink transfer type, thus expanding the range of applications of such recording systems and polyesters. The film is used as such a sublimation type base film for heat transfer.

However, in the case of using a sublimable ink layer binder that facilitates sublimation of the ink, the ink layer often adheres to the image receptor during the heat transfer operation due to inadequate adhesion between the sublimable ink layer and the base film. do. In order to improve the adhesion between the ink layer and the base film, attempts have been made to easily provide an adhesive undercoat on the interface. However, when providing an underlayer designed to improve the adhesion to the sublimable ink layer to satisfy the required degree of adhesion, even if the adhesion to the ink layer is improved, the base film due to the low compatibility therebetween There is still a possibility that the undercoat is separated from.

As a result of the inventor's study for overcoming the above problems, it has been found that the use of a polyester film having a specific structure can significantly improve the adhesion of the polyester film layer to all kinds of functional layers. On this basis, the present invention has been accomplished.

It is an object of the present invention to provide improved adhesion to biaxially oriented laminated polyester films.

Another object of the present invention is to provide a sublimation type base film for heat transfer using the biaxially oriented laminated polyester film.

It is still another object of the present invention to provide a base film for a metallized film capacitor using the biaxially oriented laminated polyester film.

In order to achieve the above object, as a first aspect of the present invention, a polyester film (B layer): made of polyester that does not have a crystalline melt peak at 230 ° C. or higher during differential thermal analysis and is a polyester film (B layer) A layer having a thickness of 2 μm or less co-extruded on at least one side of the layer (layer A): and a coating layer comprising 50% by weight or more of an acrylic resin or a urethane resin and formed on the surface of the layer A A biaxially oriented laminated polyester film is provided.

As a second aspect of the present invention, a polyester film (B layer): made of polyester that does not have a crystalline melting peak at 230 ° C. or higher in differential thermal analysis, and is formed on at least one surface of a polyester pearl (B layer) A biaxially oriented laminated polyester film comprising an extrusion-laminated layer having a thickness of 2 μm or less (layer A): and a coating layer formed on the surface of layer A, comprising at least 50% by weight of an acrylic resin or a urethane resin. A sublimation type heat transfer recording base film is provided.

As a third aspect of the present invention, a polyester film (B layer), composed of a polyester having no crystalline melting peak at 230 ° C. or higher in differential thermal analysis and having a hollow on at least one surface of the polyester film (B layer) A biaxially oriented laminated polyester film comprising an extrusion-laminated layer having a thickness of 2 μm or less (layer A): and a coating layer formed on the surface of layer A, comprising at least 50% by weight of an acrylic resin or a urethane resin. A base film for a metallized film capacitor is provided.

The biaxially oriented polyester film according to the present invention has a structure in which a polyester layer (layer A) having certain properties is laminated by co-extrusion on at least one side of a normal polyester layer. The polyester A layer consists of a polyester having the characteristic that no crystalline melt peak is present at 230 ° C. or higher, preferably 210 ° C. or higher in differential thermal analysis. “Differential thermal analysis” as referred to herein means an analysis performed at a heating rate of 10 ° C./minute using a differential scanning calorimeter (DSC). The expression “no crystalline melt peak is present” means that the top of the crystalline melt peak is not present in this temperature range. Polyesters in which the bottom of the crystalline melting peak is in the above temperature range are included in the polyesters usable in the present invention.

When the polyester constituting the A layer is crystalline, it is essential that the crystalline melting peak does not exist below 230 ° C, and the A layer may be composed of a polyester having no crystallinity. The following dicarboxylic acid and diol can be polycondensed to obtain a polyester used in the A layer.

Diols useful as layer A components include ethylene glycol, propanediol, butanediol, neopentyl glycol, pentanediol, diacid diol, octanediol, decanediol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyethylene glycol, tetramethylene and the like. to be. Dicarboxylic acids useful as other A layer components include terephthalic acid, isophthalic acid, phthalic acid, metal salts of naphthalenedicarboxylic acid, 4-sulfonylisophthalic acid, biphenyldicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid and sebacic acid. , Cyclohexanedicarboxylic acid, oxalic acid, malonic acid and the like.

Fine particles may be included in the A layer to improve the sliding characteristics of the film. As such fine particles, particles such as calcium carbonate, calcium phosphate, barium sulfate, titanium oxide, kaolin, talc, clay, alumina, silica, carbon black and the like can be used. It is also possible to use crosslinked organic particles such as crosslinked polystyrene resins and crosslinked acrylic-based resins. Only one kind of the particles may be used or two or more kinds of the particles may be mixed and used. The average size (diameter) of the particles used in the present invention is generally in the range of 0.001 to 3.0 µm, preferably 0.01 to 2.0 µm. The amount of particles used in the present invention is generally 10% by weight or less, preferably 5% by weight or less. Layer A also includes additives known to be included in the polyester film, such as fluorescent brighteners, antistatic agents, ultraviolet absorbers, lubricants, flame retardants and the like.

In the biaxially oriented laminated polyester film according to the present invention, it is essential that the A layer is present on at least one surface of the layer (B layer) composed of polyester different from the surface consisting of the A layer. The laminated structure of the polyester film of the present invention may be A / B, A / B / A or A / B / A ', where A' is the same as layer A in the composition, but the thickness is different from layer A. . The layer B itself has a laminated structure. Layer B is described in more detail later.

In the present invention, the thickness of the A layer needs to be 2 µm or less, preferably 1 µm or less, more preferably 0.5 µm or less. When the thickness of the A layer exceeds 2 µm, the film is likely to be blocked when the produced films are overlapped with each other. Although the following coating layer is provided on the A layer having a thickness of more than 2 mu m, blocking is seldom inevitable. When the thickness of the layer A is in the range of 0.01 to 0.5 μm, blocking of the film does not occur, moreover, the coating layer provided thereon may be strongly bonded. The minimum limit of the layer A thickness is 0.001 mu m. If the thickness of the A layer is less than 0.001 mu m, the bonding effect of such a layer on the coating is lowered. For the same reason, it is preferable that the thickness of the layer A 'of the laminated structure is less than 2 m.

The laminated structure of the biaxially oriented polyester film of the present invention is formed by a coextrusion method in which A and B layers are bonded and laminated when melt-extruded. Known methods such as extrusion lamination and dry lamination can be used to deposit layer A on layer B. However, in known lamination methods it is generally laminated on a film which is already biaxially oriented. On the other hand, biaxial orientation is performed after lamination by the coextrusion method.

That is, the biaxially-oriented laminated polyester film of this invention obtained by the coextrusion method is excellent in the thickness precision of A-layer, and the adhesiveness between A-layer and B-layer.

In addition, in a preferred embodiment of the present invention, which will be described in more detail below, an in-line coating system is used in which a coating solution comprising a water-soluble or water-dispersible resin is applied thereon and the obtained film is stretched in the film stretching step. In such a case, biaxial orientation is performed after lamination of the A and B layers.

The layer B of the biaxially oriented laminated polyester film of the present invention is composed of polyester different from that used for A filling. Preferably, layer B consists of polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or poly-1, 4-cyclohexanedimethylene terephthalate (PCT), and is a mixture or copolymer of said resins and other resins such as It may be composed of up to 10 mol% of the resin used for the A layer. It is recommended to produce B layer raw material by recycling part or all of the fragments produced during the film forming process. In such a case, the copolymer used for A layer is mixed with the said B layer raw material.

In the B layer, fine particles may be present in the A layer as needed. Such fine particles may be of the same kind, size and content as used in layer A. The particles of the A layer and the particles of the B layer may be the same or different from each other.

When the layer B itself has a laminated structure ratio, the fine particles may be added to the entire layer B or only to the layer forming the surface of the layer B or only to the intermediate layer. If desired, various particles may be added to the surface layer and the intermediate layer.

In addition, in the B layer, a mixture of a polymer having a compounding contraindication such as crystalline polyolefin and polyester can be used. When such mixed materials are used, the film density of layer B can be stretched in the range of 0.4 to 1.2 g / cm 3 to form voids around the polymer of the compounding taboo. In this case, the amount of polymer of the compounding contraindications is generally selected in the range of 1 to 25% by weight based on the polyester used for the layer B.

The biaxially oriented laminated polyester film of the present invention is characterized in that a coating layer containing an acrylic or urethane resin is formed on the surface of the A layer.

It will be described an acrylic-based resin that can be used in the present invention.

As the acrylic-crab resin used in the present invention, polymers composed of 70 mol% or less of other vinyl monomers and 30 mol% or more of at least one acrylic-crab monomer which can be co-polymerized with the acrylic monomer are useful.

Examples of acrylic-based monomers usable in the present invention are acrylic acid, methacrylic acid, alkyl acrylates, alkyl methacrylates, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, acrylamides and acrylonitrile. Examples of alkyl groups of alkyl acrylates and alkyl methacrylates include methyl, n-propyl, isopropyl, n-butyl, isobutyl, 2-ethylhexyl, lauryl, stearyl and cyclohexyl.

In particular, when the biaxially oriented laminated polyester film according to the present invention is used as a base film for sublimation heat transfer, preferably, the acrylic resin for coating is at least 30 mol% of at least one acrylic monomer, and It is selected from hard acrylic-based resins containing 70 mol% or less of other copolymerizable vinyl monomers and 30 mol% or less of vinyl monomers (monomers for hard fragments) capable of curing the acrylic resin.

The monomer for hard fragments used here is preferably a monomer having a glass transition temperature (Tg) of at least 30 ° C. when it becomes a homopolymer. The preferable range of Tg is 40 degreeC or more, Most preferably, it is 50 degreeC or more. When a monomer having a Tg of less than 30 ° C. is used, the necessary adhesion may not be obtained when the biaxially oriented laminated polyester film is used as the base film for sublimation heat transfer.

Conventional methods of increasing the Tg of acrylic-made resins by increasing the percentage of monomers for hard fragments have been considered impractical because this method excessively reduces the adhesion to the base polyester film. According to the invention, such a decrease in adhesiveness can be avoided due to the presence of the A layer described above. However, the Tg of the acrylic-based resin used is so high that the minimum film forming temperature is increased so that the highest value of the acrylic-based resin Tg is preferably set to 130 ° C, more preferably 110 ° C.

The monomers for the hard fragments may be acrylic-based monomers or other vinyl monomers. Examples of such monomers are alkyl acrylates, alkyl methacrylates, acrylonitrile, vinyl acetate and styrene monomers. When acrylic-based monomers or other vinyl monomers (such as vinyl acetate) are used as starting monomers of the hard acrylic-based resins, the top of the content is set at 70 mol% or less, consistent with the acrylic-based resins defined above.

In the present invention, it is recommended to use vinyl monomers having functional groups to improve the adhesion to the layer A and other functional layers or to improve the affinity for other coating materials. The functional groups can be bonded to other vinyl monomers or acrylic-based monomers that can be copolymerized together. Preferred examples of the functional group include a carbonyl group and salts thereof, acid anhydride groups, sulfone groups and salts thereof, imide groups, hydroxyalkylated amide groups, amino groups (including substituted amino groups) and salts thereof, hydroxyalkylated amino groups and salts thereof, It is a hydroxyl group and an epoxy group. Carboxyl groups and salts thereof, acid anhydride groups and epoxy groups are particularly preferred. The monomer may have two or more such groups.

As a vinyl monomer which has the said functional group, the compound which has a semi-aromatic functional group, a self-crosslinking functional group, or a hydrophilic group can be used. Examples of such compounds include the following.

Examples of the compound having a carboxyl group or a salt thereof and the compound having an acid anhydride are acrylic acid, methacrylic acid, itaconic acid, maleic acid, metal (sodium) salts of these carboxylic acids, ammonium salts and maleic anhydride.

Examples of compounds having a sulfone group or salts thereof are vinyl sulfonic acid, styrenesulfonic acid, metal (sodium) salts of these styrene sulfonic acids, and ammonium salts.

Examples of the compound having an amide or hydroxyalkylated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, hydroxymethylated acrylamide, hydroxymethylated methacrylamide, ureidovinyl ether, β-ureido Isobutylvinyl ether and ureido are ethyl acrylates.

Examples of compounds having amino groups or hydroxyalkylated amino groups or their salts include diethylaminoethylvinyl ether, 2-aminoethylvinyl ether, 3-aminopropylvinyl ether, 2-aminobutylvinyl ether, dimethylaminoethyl methacrylate, Dimethylaminoethylvinyl ether, a compound having such a hydroxyalkylated amino group; And tetravalent ammonium groups by quadrants such as alkyl halides, dimethyl sulfuric acid and sultone.

Examples of the compound having a hydroxy group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxyvinyl ether, 5- Hydroxypentylvinyl ether, 6-hydroxyhexylvinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate and polypropylene glycol monomethacrylate.

Examples of the compound having an epoxy group are glycidyl acrylate and glycidyl methacrylate.

Other compounds such as butylvinyl ether, maleic acid monoalkyl esters, maleic acid dialkyl esters, fumaric acid monoalkyl esters, fumaric acid dialkyl esters, itaconic acid monoalkyl esters, itaconic acid dialkyl esters, methyl vinyl ketones, vinyl chloride , Vinylidene chloride, vinyl pyridine, vinyl pyrrolidone, vinyltrimethoxysilane and the like can be used with the above-mentioned compounds.

The biaxially oriented laminated polyester film of the present invention is preferably prepared using an in-line system in which a coating solution comprising a water soluble or water dispersible resin is applied onto the base film, and then the coated film is stretched in the film stretching step. do. From this point of view, the acrylic resin used in the present invention preferably contains an anionic or cationic group and is a water-soluble or water-dispersible resin.

Examples of compounds containing anionic groups are carboxyl groups, sulfone groups and salts thereof. Tetravalent ammonium salts are examples of cationic groups. Acrylic-based resins containing anionic or cationic groups can be obtained by selecting the appropriate vinyl monomers above. The content of anionic or cationic groups is preferably in the range of 0.05 to 8% by weight. When the content of the anionic or cationic group is less than 0.05% by weight, the water-soluble or water dispersibility of the acrylic resin may be lowered. When the content is more than 8% by weight, the water resistance of the coating layer is further lowered or the film absorbs the water. Easy to block.

"Urethane-based resins" refer to high molecular weight compounds with urethane bonds and include polyols, polyisocyanates, chain extenders and crosslinkers.

As the polyol, polyethers such as polyoxyethylene glycol, polyoxypropylene glycol and polyoxytetramethylene glycol; Polyesters obtained from dehydration of dicarboxylic acids and glycols such as polyethylene adipate, polyethylene-butylene adipate and polycaprolactone; Polycarbonate having a carbonate bond; Acrylic-based polyols, and castor oil.

As polyisocyanate, polyylene diisocyanate, phenylene diisocyanate, 4,4'- diphenylmethane diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, 4,4'- dicyclohexyl methane diisocyanate, isophorone diisocyanate And the like can be used.

As chain extenders or crosslinkers, ethylene glycol, propylene glycol, butanediol, hexanediol, diethylin glycol, trihydroxymethylated propane, hydrazine, ethylenediamine, diethylenetriamine, 4,4'-diaminodiphenylmethane , 4,4'-diaminodicyclohexylmethane, diethanolamine and water can be used.

The urethane-based resin used in the present invention is preferably a resin containing an anionic or cationic group and is water-soluble or water dispersible for the same reasons as in the case of the acrylic-based resin. Polyurethane-based resins having an anionic group can be obtained by bonding a compound having an anionic group to the resin by copolymerization or graft reaction. The anionic group is suitably selected from sulfonic acid groups, carboxylic acid groups, phosphoric acid groups and salts thereof. The content of anionic or cationic groups is preferably in the range of 0.05 to 8% by weight for the same reasons as for the acrylic-based resins.

In particular, polyurethane-based resins having anionic groups include, for example, methods using polyols, polyisocyanate compounds, chain extenders, and compounds having anionic groups as the polyurethane-forming component; A method in which an unreacted isocyanate group of the produced polyurethane reacts with a compound having an anionic group; Or groups with active hydrogens of the polyurethane can be prepared by the reaction with certain compounds.

The biaxially oriented laminated polyester film according to the present invention has a coating layer containing the aforementioned acrylic-based resin or urethane-based resin (hereinafter referred to as coating material) on the surface of the A layer. The coating solution for forming the coating layer is preferably prepared using an aqueous medium for safety and hygiene, and substantially by dissolving or dispersing the coating material in water. The coating material can be easily dissolved or dispersed in water depending on the type of monomer used. If desired, a small amount of organic solvent can be used as a dissolution or dispersion aid in the preparation of the coating solution.

In the type of coating solution using water as a medium, an acrylic-based resin or a urethane-based resin may be a coating solution forcibly dispersed by a surfactant or other suitable sample, but a hydrophilic nonionic component such as polyether Or a self-dispersing coating solution comprising a coating material comprising a cationic group such as a tetravalent ammonium salt. Most preferred are water soluble or water dispersible coating compositions using coating materials having anionic groups.

Particles may be included in the coating solution to improve the sliding property of the coating layer. Such particles may be inorganic or organic particles.

Examples of inorganic particles suitable for this purpose are silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, calcium phosphate, titanium oxide, barium sulfate, carbon black, molybdenum sulfide and antimony oxide. Examples of organic particles are particles of homopolymers or copolymers such as polystyrene, polyethylene, polyamides, polyesters, polyacrylic acid esters, epoxy resins, polyvinyl acetates and polyvinyl chlorides. Such copolymers may include crosslinkers. Particles such as silicone resins, fluorine resins and the like can also be used as organic particles.

In addition, the coating solution may include a cross-linking agent for improving the semiblock properties, water resistance, solvent resistance and mechanical strength of the coating layer. Examples of crosslinkers that can be used for this purpose are hydroxymethylated or hydroxyalkylated-urea-based compounds, melamine-based compounds, guanamine-crab compounds, acrylamide-crab compounds and polyamide-based compounds. Compounds, isocyanate compounds, epoxy compounds, aziridine compounds, silane coupling agents, titanium coupling agents, zirco-aluminate coupling agents, peroxides, heat- and photo-reactive vinyl compounds, and photosensitive resins.

In addition, the coating solution may include other necessary additives such as antifoaming agent, coating performance improving agent, thickening agent, antistatic agent, organic lubricant, antioxidant, ultraviolet absorbent, foaming agent, dye, pigment and the like.

The content of the coating material in the coating layer is at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, particularly preferably at least 80% by weight. If the content of the coating material in the coating layer is less than 50% by weight, the performance of the preferred adhesive of the present invention cannot be obtained.

The thickness (final dry thickness) of the coating layer is generally in the range of 0.01 to 2 μm, preferably 0.02 to 1 μm, more preferably 0.03 to 0.2 μm. Blocking of the film is caused when the thickness of the coating layer exceeds the above range, whereas when it is below the above range, it is difficult to obtain a uniform coating layer, resulting in a nonuniform coating on the product.

Various coating apparatuses, such as the reverse roll coater, gravure coater, rod coater, air doctor coater, etc. described in `` Yuji Harasaki: Coating System, Maki Shoten, 1979 '', are applied on the polyester film (layer A). It can be used to apply the solution. Application of the coating solution may be carried out at a step outside the film forming process, but is preferably performed during the film forming process. To carry out coating in the film forming process, for example, the following method can be used: The coating solution is applied onto the non-stretched polyester film and the film is subsequently drawn biaxially: continuously or simultaneously: the coating solution is a uniaxially stretched film And then the film is stretched in a direction orthogonal to the initial uniaxial stretching direction: the coating solution is applied onto the biaxially stretched polyester film and the film is then further stretched in the transverse and / or longitudinal direction.

The thickness ratio of the A layer to the B layer (A layer thickness / B layer thickness) of the biaxially oriented laminated polyester film of the present invention is generally 1 or less, preferably 0.7 or less, more preferably 0.5 or less, most preferably Is less than 0.2. When this thickness ratio exceeds 1, the mechanical strength of the film tends to be lowered and the layer A surface is likely to be blocked.

The minimum value of the biaxially oriented laminated polyester film thickness according to the present invention is generally 0.5 탆, preferably 1 탆. If the film thickness is less than 0.5 mu m, the film may not have satisfactory strength. The top of the film thickness is 500 μm, preferably 100 μm, more preferably 50 μm, most preferably 25 μm. The most suitable film thickness is selected in the above range depending on the intended use of the film.

The method for forming the biaxially oriented polyester film according to the present invention is described below.

The polyester resin for layer A and the polyester resin for layer B are each dried and then extruded from each extruder and laminated before the slot die by a feed block coextruder or die head of a multi-manifold coextruder. The layers are applied and extruded onto a sheet and cooled and solidified in a casting drum to obtain an unstretched film. It is recommended to use electrostatic pinning techniques for cooling and can solidify as a good flat film.

Preferably, a # 600-mesh or finer mesh size filter may be provided to each resin extruder for extrusion while filtering to prevent contamination of contaminants and to reduce silver spots. In addition, it is recommended to install a fixed mixer and metering pump at each melting line of the resin as it can contain films of uniform thickness.

In the present invention, the non-stretched film is biaxially stretched so that the non-stretched film is biaxially oriented. For stretching, it is preferable to use the continuous biaxial stretching method in which the film is first drawn in the longitudinal direction and then stretched in the transverse direction. Stretching in the longitudinal direction is performed by selecting suitable conditions (stretching temperature of 50 to 180 ° C and stretching ratio of 2.0 to 9.0 times) according to the polyester composition.

The stretching may be performed in a single step, but in order to improve the uniformity of the A layer thickness, it is preferable to carry out in two or more steps within the stretching temperature and the stretching ratio in the above-defined range. The stretching temperature may be the same at every step or may vary from step to step. The stretching speed for stretching in the longitudinal direction is preferably in the range of 5,000 to 500,000% / min in order to obtain uniformity of the entire film thickness.

In the present invention, the coating treatment is preferably performed in a single step after stretching in the longitudinal direction. In order to improve the coating performance of the coating solution and the adhesion to the film, a chemical treatment or a discharge treatment is applied on the film before the coating treatment.

Tenters are generally used for stretching in the transverse direction. Transverse stretching is preferably performed under the following conditions:

Stretching temperature = 80 to 170 ° C;

Draw ratio = 3.0-6.0 times;

Elongation = 100 to 200,000% / min.

Thereafter, the film is stretched in the longitudinal, transverse or bi-directional as necessary.

In the present invention, the synthesized film is passionate. Thermosetting is preferably carried out at 180 to 250 ° C, more preferably at 210 to 240 ° C for 1 to 600 seconds.

According to the above-described process of the present invention, drying of the coating layer is carried out simultaneously and the coating thickness is set according to the draw ratio so that a film suitable for use as a polyester base film can be produced at a relatively low cost.

In the present invention, the layer A is melted or softened and its planar orientation is almost eliminated by heat-treatment, but it is preferable to set the heat treatment temperature above the crystalline melting point of the polyester constituting the layer A. If the polyester does not have a crystalline melting point, the thermosetting temperature is preferably set above the thermal softening point of the polyester. This can enhance the adhesion between the coating layer and the polyester film. The reason for this phenomenon is not clearly known, but it is believed that the layer A was melted or softened during thermosetting, so that the coatings provided on the layer A and its surface were fused together at the interface to provide strong adhesion.

In the present invention, the coating solution may be applied to both sides of the laminated polyester film or only one side (layer A). When the coating solution is applied only on one side, the coating layer of the composition not included in the present invention may be formed as desired on the other side to impart different properties to the biaxially oriented polyester film of the present invention. The coating solution used in the present invention may be a mixture of acrylic-based resins or urethane-based resins, and other materials such as ester resins, vinyl-based resins, etc. may be used to improve the coating solution or coating layer as necessary. It may include. Further, in order to further improve the adhesion and coating performance of the coating layer of the biaxially oriented laminated polyester film of the present invention, a discharge treatment is applied on the coating layer after formation of the coating layer.

In the biaxially oriented laminated polyester film of the present invention, various functional layers can be formed on the surface of the coating layer. For example, a functional layer comprising at least one resin selected from gelatin-based resins, PVA-based resins, PVB-based resins, cellulose-based resins and derivatives thereof is formed on the polyester film. Can be. All known forms of resin can be used to form such functional layers. Such resins are advantageously used as binders for functional layers in photographic films, ink receptive films and plating-forming films. The biaxially oriented laminated polyester film of the present invention has excellent adhesion to the functional layer comprising the polymer, whereby these films are useful as base films for photographic films, ink receiving films, plating-forming films.

Moreover, due to the good adhesion to the metal-deposited layer, the biaxially oriented laminated polyester film according to the present invention is a packaging material, decorative material, gold or silver thread material, indicator material, wiring board material, magnetic recording material, capacitor Suitable for film, window attachment, etc.

Hereinafter, the sublimation type heat transfer base film which concerns on this invention using the biaxially-oriented laminated polyester film mentioned above is demonstrated.

The base film of the present invention can be used for conventional sublimation heat transfer. The lowest value of the base film thickness is generally 0.5 μm, preferably 1 μm, more preferably 2 μm, most preferably 3 μm for the same reasons as described above. The highest value of the base film thickness is generally 15 μm, preferably 10 μm, more preferably 8 μm, particularly preferably 6 μm. If the base film has a thickness larger than the above-described highest value, satisfactory printing sensitivity cannot be obtained.

The sublimable ink layer formed on the surface of the coating layer of the base film consists of a yellow, magenta or cyan dye dispersed in a sublimable solid dye, such as a binder. Typical examples of sublimable dyes usable in the ink layer are as follows:

(a) Yellow: color index disperse yellow 7 (eg yellow 5RX (trade name, available from BASF).

(b) Magenta: Color Index Disperse Red 60 (e.g., RED-FBL (trade name, available from Sumitomo Chemical Corporation)).

(c) cyan: color index solvent blue 108.

It is ideal to use a sublimable dye that sublimes in a relatively narrow range of moving temperatures close to the optimum temperature. Dyes that can be used for heat transfer are in the form almost molecular weight in the range of 230 to 370. Such dyes not only have sublimation suitable for dyeing, but also allow for easy dispersion of the dye inside the article to be dyed. Structurally, such dyes preferably do not include ionic groups such as sulfonyl groups or carboxyl groups, but suitably include polar groups such as hydroxy groups, amino groups, nitro groups or sulfone groups.

The binder used in the sublimable ink layer is preferably a binder having specific properties that allow the dye molecules to easily sublimate and allow uniform dispersion of the dye. Examples of such binders are cellulose-based resins, acrylic-based resins, polyvinyl alcohol (PVA) -based resins, polyvinyl butyral (PVB) -based resins and polyamide resins. Among these resins, cellulose-based resins and PVB-based resins are preferably used, the former being most preferred.

With regard to the dye content of the sublimable ink layer, more content provides a higher color concentration, but the dye content can cause problems in the dispersibility of the dye in the binder, so it must be determined in consideration of the properties of the product required for the use of the tablet. do. The thickness of the sublimable ink layer is preferably in the range of 0.5 to 10 mu m, most preferably in the range of 1 to 5 mu m.

The base film for sublimation heat transfer according to the present invention has excellent adhesion to the sublimable ink layer, and when used for transfer recording, the sublimation ink layer does not cause peeling and is adhered to the image receiving paper to form an excellent image. do.

Hereinafter, the base film for metallized film capacitors of this invention using the biaxially-oriented laminated polyester film mentioned above is demonstrated.

The biaxially oriented laminated polyester film of the present invention can be used as a base film for conventional metallized film capacitors. The thickness of the base film may be the same as the above-described range.

Metals used for the deposition include aluminum, palladium, zinc, nickel, gold, silver, copper, indium, tin, chromium, titanium, silicon and the like. Of these metals, aluminum is particularly preferred. Oxides of these metals can also be used.

The thickness of the deposited metal film is generally in the range of 1 to 500 nm, but it is preferable to reduce the thickness as much as possible within a range that does not lower the effect. The highest value of the deposition thickness is 500 nm, preferably 100 nm, more preferably 80 nm and most preferably 60 nm.

Deposition is generally carried out by vacuum deposition, but other methods such as electrodeposition or sputtering can be used. A deposited metal film is provided on both sides of the base film. The deposited metal film may be subjected to other treatments such as suitable surface treatment or coating treatment with a resin.

The capacitor can be manufactured according to a conventional method. For example, the two metal films may be overlapped with each other, and may be wound or a plurality of the metallized films may be stacked together to form a capacitor component. Such components may include thermal compression, taping, metallikon, and voltage. Necessary treatments such as treatment, surface sealing at both ends, and bonding of lead wires are applied to form the capacitor. In this process, the capacitor component may be a combination of the biaxially oriented laminated polyester film of the present invention and the other double sided metallized polyester film.

Since the biaxially oriented laminated polyester film according to the present invention has excellent moisture heat resistance, the long-term reliability of the capacitor can be improved.

Example

The invention is illustrated in detail by the following examples. However, these examples are merely illustrative and do not limit the scope of the present invention.

The evaluation method used in the following examples and comparative examples is described below. In addition, in the following examples and a comparative example, all the "parts" are a "weight part" unless there is particular notice.

(1) layer thickness

The biaxially oriented laminated polyester film sample is fixed by being embedded in the resin so that the cross section in the thickness direction can be observed, and is cut to 100 nm thickness by microrom from the sample and is a transmission electron microscope (H-9000, manufactured by Hitachi). Observed to determine the thickness of each layer (10,000 to 20,000 times magnification; acceleration voltage: 100 kV). (2) Crystalline melting point (Tm) of polyester

Using a differential calorimeter (SSC-580 DSC-20, manufactured by Seiko Electronics), about 10 mg of the polymer was heated at a heating rate of 10 ° C./min in medium nitrogen and the temperature corresponding to the top of the heat absorption peak by the crystalline melt was measured. It measures and calls it crystalline melting point (degreeC).

(3) Evaluation of adhesiveness

(i) adhesion to gelatin

Photo gelatin 5% aqueous solution (P-2225, manufactured by Nitta Gelatin) was applied on the surface of the coating layer of the sample film so as to have a dry coating thickness of 0.6 μm, followed by heat-air drying at 80 ° C. for 1 minute, for evaluation. To prepare. Such an evaluation film was placed in an atmosphere of 23 ° C. and 50% RH for 24 hours in order to control its temperature and humidity content, and then an 18 mm wide cellophane adhesive tape (manufactured by Nichihan) was used in such a way that no air cell was held in the tape. The film is glued 7 cm long on the gelatin-coated side of the film and then a constant load is applied on the adhesive tape by manual load rolls so that the tape adheres quickly to the film. Subsequently, the film with the adhesive tape attached thereto is subjected to a 180 ° peel test in which the film is attached in the vertical direction, and 500 g weight is connected to the top of the cellophane tape and dropped by gravity over a gap of 45 cm. Adhesiveness is evaluated based on the following three criteria.

(Circle): The peeled area | region of an ink layer is less than 10% (excellent adhesiveness).

(Triangle | delta): The peeled area | region of an ink layer is 10 to 50% (excellent adhesiveness).

X: The peeled area | region of an ink layer exceeds 50% (inferior adhesiveness)

(ii) adhesion to polyvinyl alcohol (PVA)

Adhesion to PVA was evaluated in the same manner as described in paragraph (i) above except that a 5% aqueous solution of PVA saponified to Nippon Synthetic Chemicals, Inc. was used as the ink.

(iii) adhesion to polyvinyl butyral (PVB)

Adhesion to PVB is described above except that 5% aqueous solution of Butval B-98 (trade name, manufactured by Mitsubishi Monsanto Chemical Co., Ltd., manufactured by butyrating the hydroxy group of butylaldehyde fully saponified PVA with butyral) is used as an ink. It is evaluated in the same way as described in i).

(iv) adhesion to cellulose;

Adhesion to cellulose was evaluated in the same manner as described in (i) above except that hydroxypropylmethyl cellulose 2% aqueous solution (Marpolose MP, manufactured by Matsumato Yushi Seiyaku) was used as the ink. do.

(4) half-block characteristics

The films were placed superimposed on one another and processed under a pressure load of 10 kgf / cm 2 for 20 hours at 40 ° C. and 80% RH-thermostat. The film is then cut to 10 cm width and the (half) block properties of the film are determined according to the ASTM-D-1893 method, where the adhered film is peeled off using the piano wire and evaluated according to the following three criteria:

(Circle): The force required for peeling is less than 30 gf.

(Triangle | delta): The force required for peeling is 30-100 gf.

X: The force required for peeling is 100 gf or more.

(5) adhesiveness to the sublimable ink layer

Adhesive tape Scotch Mending Tape 810 (trade name, manufactured by 3M Corporation) is attached to the sublimable ink layer and peeled off quickly so that no air cells enter. The peeling degree of the ink layer is determined. Using yellow and cyan inks, the adhesion to the sublimable ink layer at 25 ° C. is measured and evaluated according to the following three criteria:

(Circle): The peeled area | region of an ink layer is less than 10% (excellent adhesiveness).

(Triangle | delta): The peeled area | region of an ink layer is 10 to 50% (excellent adhesiveness).

X: The peeled area | region of an ink layer exceeds 50% (inferior adhesiveness)

(6) Disorderly Delivery of Sublimable Ink to Image Receptors

200 µm thick dyed image receptor and heat transfer recording sheet consisting of 10 parts polyester (Vylonal MD-1200, manufactured by Toyo Boseki) and 1 part silica particles (Nipsil E200A, manufactured by Nippon Silica Kogyo) The transfer recording is performed using a thermal head having an 8-dot / mm-heating resistor write density, superimposed on each other on a high quality paper, and applying 0.3 watts / dot of power for 10 ^-3 seconds thereon. Whether or not the sublimable ink has passed on the image receiving surface is visually observed and evaluated according to the following three criteria.

(Circle): The substance letter movement of an ink layer does not occur.

(Triangle | delta): The disordered movement of ink is observed somewhat, and the commercial value of a product falls.

X: Disordered movement of the ink is often observed, and the laminate cannot be used substantially.

(7) adhesion to the deposited metal film

Aluminum is deposited to 45 nm using a resistive heat-type metallization apparatus with the pressure in the vacuum chamber set to 10 ⁻⁴ Torr or less. On the deposited metal surface of the metal and the film, two packs of curable adhesive based on polyurethane-based were coated at a dry weight of 5 g / cm 2 and then a polyester film of the same thickness as the base polyester film was subjected to a general dry lamination method. Followed by aging at 40 ° C. for 48 hours. The resulting laminate was cut into small pieces 15 mm wide and immersed in hot water at 60 ° C. for 30 minutes (hydrothermal treatment).

The chisel of the hydrothermally treated sample is partially stripped off and then the sample is stripped off in a T-shape at a rate of 100 mm / min by the stripping tester. Adhesion is evaluated according to the following three criteria:

(Circle): The force required for peeling is 100 gf or more.

(Triangle | delta): The force required for release is 10 gf or more and less than 100 gf.

X: The force required for peeling is less than 10 gf.

(8) change in capacitance

(i) no load test

The sample capacitor is left for 1000 hours at 60 ° C. and 95% RH-atmosphere, and the change in capacitance is evaluated based on the initial capacitance. That is, the initial capacitance is subtracted from the capacitance after 1000 hours, and the obtained value is divided by the initial capacitance and expressed as a percentage.

(ii) load test

The sample capacitor is left for 1000 hours at 60 ° C. and 95% RH-atmosphere while applying a DC voltage of 60 V / μm through the electrodes, and the change in capacitance is evaluated based on the initial capacitance. That is, the initial capacitance is subtracted from the capacitance after 1000 hours, and the obtained value is divided by the initial capacitance and expressed as a percentage.

The polyester resin used in the following examples is prepared by the following method.

Polyester resin 1

80 parts of dimethyl terephthalate, 20 parts of dimethyl isophthalate, 65 parts of ethylene glycol, 55 parts of 1,4-butanediol and 0.09 parts of magnesium acetate are heated in a reactor to carry out the transesterification reaction while distilling methanol. After the start of the reaction, the reaction mixture is heated to 230 ° C. for about 4 hours to substantially complete the transesterification reaction. Then 0.4 parts of ethyl phosphate and 0.04 parts of antimony trioxide are added and the pressure of the reaction system is gradually reduced to reach 1 mmHg at atmospheric pressure. After 4 hours, the reaction system is returned to atmospheric pressure to yield a polyester resin (polyester 1). No crystalline application peak is observed in differential thermal analysis of polyester 1.

Polyester resin 2

60 parts of dimethyl terephthalate, 40 parts of dimethyl isophthalate, 55 parts of 1,4-butanediol and 0.09 parts of magnesium acetate are heated in a reactor to carry out transesterification while distilling methanol. After the start of the reaction, the reaction mixture is heated to 230 ° C. for about 4 hours to substantially complete the transesterification reaction. Then 0.4 part of ethyl phosphate and 0.04 part of antipan trioxide are added and the pressure of the reaction system is gradually reduced to reach 1 mmHg at atmospheric pressure. After 4 hours, the reaction system is returned to atmospheric pressure to contain the polyester resin (polyester 2). The crystalline melting point of polyester 2 is 151 ° C.

Polyester resin 3

100 parts of dimethyl terephthalate, 65 parts of ethylene glycol and 0.09 parts of magnesium acetate are heated in a reactor to carry out the transesterification reaction while distilling methanol. After the start of the reaction, the reaction mixture is heated to 230 ° C. for about 4 hours to substantially complete the transesterification halftone. At this point, amorphous silica with an average particle diameter of 1.25 μm is added in the form of an ethylene glycol slurry so as to be present at 0.1% concentration in the polymer. Then 0.4 parts of ethyl phosphate and 0.04 parts of antimony trioxide are added and the pressure of the reaction system is gradually reduced to reach 1 mmHg at atmospheric pressure. After 4 hours, the reaction system is returned to atmospheric pressure to yield a polyester resin (polyester 3). The crystalline melting point of polyester 3 is 259 ° C.

Coating materials used in the following examples are as follows.

A1 (acrylic-based resin): 25 mol% of methyl methacrylate (105 캜), 30 mol% of n-butyl acrylate (-54 캜), 40 mol% of styrene (100 캜) and 5 mol% of ammonium salt of acrylic acid A water-dispersible acrylic resin consisting of (106 ° C).

A2 (acrylic-based resin): water-dispersible acrylic consisting of 65 mol% of methyl acrylate (105 ° C), 30 mol% of n-butyl methacrylate (-54 ° C) and 5 mol% (106 ° C) of ammonium salt of acrylic acid Crab resin.

A3 (acrylic-based resin): 50 mol% of ethyl acrylate (22 ° C), 35 mol% of n-butyl methacrylate (-54 ° C), 10 mol% of 2-hydroxyethyl methacrylate (55 ° C) And an ammonium salt of methacrylic acid (130 ° C.).

Note: The temperature in parentheses is the Tg of the homopolymer.

B1 (urethane-based resin): 472 parts of diethyl carbonate, 416 parts of 1,5-pentanediol and 472 parts of 1,6-hexanediol were reacted at 120 to 200 ° C for 15 hours. The reaction system is then set to 150 ° C. and the residual ethanol and unreacted diol are sufficiently distilled under reduced pressure of 10 to 50 mmHg to give polycarbonate polyol. The hydroxyl value of the obtained polyol is about 66, and the average molecular weight is about 2000. 500 parts of such polycarbonate polyol, 160 parts of tolylene diisocyanate, 58.5 parts of dihydroxymethylated propane having a carboxyl group neutralized with triethylamine and 1647 parts of methyl ethyl ketone (MEK) were fed to the reactor for 4 hours at 80 ° C. Reaction. The obtained solution was slowly added to 1562 parts of distilled water with stirring, and 106.5 parts of 20% isophoronediamine aqueous solution were added, and then the mixed solution was heated to 40 ° C for a polymerization reaction for 1 hour. The MEK is removed under reduced pressure to give a polycarbonate polyurethane emulsion B1 of 30% solids.

B2 (urethane-based resin): A polycarbonate polyurethane emulsion B2 is obtained by carrying out the process for producing B1, except that 1,4-butanediol is used instead of 1,5-pentadiol.

B3 (urethane-based resin): A polycarbonate polyurethane emulsion B3 is obtained by performing the above production process of B1, except that 1,4-butanediol is used instead of 1,6-hexanediol.

C1 (polyester resin): The water-dispersible polyester resin consists of 35 mol% of terephthalic acid, 5 mol% of sodium sulfoisophthalic acid, 49 mol% of ethylene glycol and 1 mol% of diethylene glycol.

Example 1

The polyester resin 1 used for the A layer and the polyester resin 3 used for the B layer were dried at 180 ° C. for 4 hours, respectively, and then the three-layer ball was opened at an extrusion temperature of 280 ° C. for the A layer and 290 ° C. for the B layer. Melt extrusion is carried out by an extruder. In this operation, both types of resins are filtered by a # 600-mesh filter and combined and laminated by a feed block to provide an A / B / A laminated structure.

The laminate is released from the slot die into the sheet and cooled and solidified on a 30 ° C. casting roll while applying the electrostatic pinning technique to obtain a three-layer unstretched film. The charge rate of each extruder is set so that the surface of layer A has the thickness shown in Table 1.

The non-stretched film thus obtained is stretched 2.9 times longitudinally at 83 ° C. by roll stretching, and then further stretched 1.25 times at 76 ° C. FIG. Next, the casting solution of the composition of Table 1 is applied on both sides of the stretched film. This film was then introduced into a tenter and stretched 3.8 times in the width direction at 110 ° C. and heat-cured at 230 ° C. for 15 seconds to give a biaxially oriented laminated polyester film having a total thickness of 50 μm and a coating layer thickness of 0.12 μm. The adhesive evaluation result of the obtained film is shown in Table 1.

Example 2-5

The biaxially oriented laminated polyester film was obtained by performing the method of Example 1 except that the composition of the coating solution was changed as shown in Table 1. The adhesive evaluation of the obtained film is shown in Table 1.

Example 6

The polyester resin 3 used in Example 1 was uniformly mixed with 20% by weight of crystalline polypropylene having a melt flow index of 4.5, and the obtained mixture was used as the resin for the B layer (the resin for the B layer was 3 'in Table 1). Is displayed). Polyester resin 1 is used as resin for polyester A layers. The two kinds of resins were each dried and melt extruded by the same three-layer coextruder as used in Example 1 at an extrusion temperature of 280 ° C. for layer A and 290 ° C. for the B layer. In this operation, both types of resins are screened by a # 600-mesh filter and joined and stacked by a feed block to provide an A / B / A lamination structure.

The laminate is extruded from the slot die into sheets and cooled and solidified on a 30 ° C. casting roll while applying electrostatic pinning techniques to obtain a three-layer unstretched film. This film is treated in the same manner as in Example 1 to give a biaxially oriented laminated polyester film. The adhesive evaluation result of the obtained film is shown in Table 1.

Comparative Examples 1 and 2

The biaxially oriented laminated polyester film was obtained by performing the method of Example 1 except that the composition of the coating solution was changed as shown in Table 2. The evaluation result of such a film is shown in Table 2. In Comparative Example 2, the thickness of the A layer was changed to 4.0 μm.

Comparative Example 3

The method of Example 1 was carried out except that polyester resin 3 was used as a starting material and melt-extruded using a single-layer extruder instead of a co-extruder at an extrusion temperature of 290 ° C. without laminating other kinds of polyester. A microaxially oriented polyester film is obtained. The adhesive evaluation results of such a film are shown in Table 2.

Comparative Example 4

The method of Example 1 was followed except that no coating layer was provided to give a biaxially oriented polyester film. The adhesive evaluation result of the obtained film is shown in Table 2.

Table 1

TABLE 2

Example 7-12 and Comparative Example 5-8 (base film for sublimation heat transfer)

The biaxially oriented laminated polyester film was obtained by carrying out the method of Examples 1 to 6 and Comparative Examples 1 to 4, except that the overall film thickness was changed to 4.5 mu m.

Benzophenone-3,3 ', 4,4'-tetracarboxylic anhydride, tolylene diisocyanate (80 mol%) and 4,4'-diphenylmethane diisocyanate (20 mol%) on the uncoated side of the film Heat resistance and high slip of 0.10 μm thickness consisting of 86 parts of polyimide obtained from the above, 7 parts of calcium carbonate particles having an average diameter of 0.07 μm and 7 parts of fluorine-based silicone oil (FL-100, manufactured by Shin-Etsu Chemical Co., Ltd.) It provides a coating layer of the castle.

On a coating surface of the film, a 2.0 μm thick sublimable ink layer consisting of 10 parts of Kayaset B (manufactured by Nippon Kayaku), 15 parts of cellulose acetate propionate, 2 parts of silica gel, and 1 part of hydroxymethylated melamine was formed. A heat transfer recording medium is produced. The evaluation results of the obtained samples of the heat transfer recording medium are shown in Tables 3 and 4.

The test results of the semiblock properties of the biaxially oriented laminated polyester film are shown in Tables 3 and 4.

TABLE 3

Table 4

Examples 13-17 and Comparative Examples 9-12 (base films for metallized film capacitors)

The biaxially oriented laminated polyester film was obtained by performing the method of Example 1 except that the coating layer thickness and the total film thickness were changed to 0.05 µm and 9.0 µm, respectively, and the coating layer composition was changed as shown in Table 5. In Example 17, polyester resin 3 was used for the A layer, and in Comparative Example 11, polyester 3 was used as the starting material, and the material was extruded by a single-screw extruder, not a coextruder, to obtain a 9 μm thick single layer biaxially oriented polyester. To obtain a film.

On each coating side of the film, aluminum was deposited at 45 nm using a resistive heating metallizer under pressure in a vacuum chamber set to less than 10 ⁻⁴ Torr. Aluminum was deposited into marginally small pieces in the longitudinal direction of the polyester film (8 mm wide midpoint and 1 mm wide margin). Each of the obtained metallized polyester films is cut with a 4.5 mm wide tape with a margin of 1 mm along the left or right edge. Then, one sheet of metallized polyester film with left margin and one sheet with right margin are cut. The 0.5 mm long deposits are combined to protrude at an angle and are wound by shifting positions. The wound film is pressurized at a pressure of 50 kg / cm 2 at 150 ° C. for 5 minutes.

Then, both chisels of the wound film are thermally methaconized, followed by bonding lead wires and injecting a liquid bisphenol A epoxy resin, followed by heat-fusion on the surface of the powdered epoxy resin to form a sheath with a minimum thickness of 0.5 mm. To obtain a film capacitor with a static capacitance of 0.1 mu F. The evaluation results of the metalized film capacitors thus obtained are shown in Tables 5 and 5.

As shown in Table 5, the film capacitor metallized using the base film of the present invention has excellent dielectric properties and moisture heat resistance, and the change in capacitance is minimized. In addition, the workability of manufacturing and fixing the capacitor is excellent.

Table 5

Table 6

Note: In Table 6, Comparative Example 11 is a single layer film.

Claims (9)

An A layer having a thickness of 2 μm or less laminated on at least one surface of another polyester layer, the polyester having no crystalline melting peak at 230 ° C. or higher in differential thermal analysis; And a coating layer formed on the surface of layer A, wherein the coating component comprises 50% by weight or more of acrylic resin or urethane resin. The method of claim 1, wherein the acrylic resin is at least 30 mol% of at least one acrylic-based monomer, 70 mol% or less of other vinyl monomers copolymerized with the acrylic-based monomer, and their homopolymers as hard fragment monomers. A biaxially oriented laminated polyester film which is a hard acrylic resin containing 30 mol% or more of a glass monomer having a glass transition temperature (Tg) of 30 ° C. or more and copolymerizable with the acrylic monomer. 3. A biaxially oriented laminated polyester film according to claim 2, wherein said hard fragment monomer is at least one vinyl monomer selected from alkyl acrylate, alkyl methacrylate, acrylonitrile, vinyl acetate and styrene monomer. The biaxially oriented laminated polyester film according to claim 1, wherein the acrylic resin or urethane resin is water-soluble or water dispersible. The biaxially-oriented laminated polyester film of claim 4, wherein the acrylic resin or urethane-resin comprises 0.05 to 8% by weight of an anionic group or a cationic group. Sublimation heat transfer base substrate comprising the biaxially oriented laminated polyester film of claim 1. The base film for sublimation heat transfer according to claim 6, wherein the coating component is an acrylic resin. The base film for metal film capacitors containing the biaxially-oriented laminated polyester film of Claim 1. The base film of claim 8, wherein the coating component is a urethane-based resin.