JPH0571617B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is a polyester film having improved slip properties and a coating layer with improved adhesion, antistatic properties, transparency, coating strength, etc. It is useful as a base material in various applications. [Prior art] Biaxially stretched polyester film has excellent transparency, dimensional stability, mechanical properties, heat resistance, electrical properties, gas barrier properties, chemical resistance, etc., and is used as a packaging material,
It is used as a base material for electrical insulating materials, metal vapor deposition materials, photosensitive materials using silver salts, diazo compounds, photosensitive resins, etc., electrophotographic materials, magnetic recording materials, etc. Recently, as magnetic recording media have become more densely recorded and capacitors have become more capacitive, polyester films used are increasingly required to be flat and have good sliding properties, that is, smoothness. Films with smoothness and good transparency are required for plate making, electrophotography, labels, window affixing films, vapor-deposited decorative films, and the like. Even the back-treated layers of magnetic recording paper, thermal transfer paper, etc. are required to have high coating strength and slip properties. Furthermore, in these applications, a film that is not easily charged is required as well as the above characteristics. Conventional methods for improving the slipperiness of polyester films include adding fine organic or inorganic particles to the film (added particle method);
There are methods based on the composition of the polyester film, such as a method in which transesterification catalyst residue is precipitated during polyester polymerization (precipitated particle method), a method using polymer blends, and a method in which an organic lubricant is blended. However, in the methods using these compositions, if one of the slipperiness and flatness improves, the other one deteriorates, and the reality is that it is difficult to improve both of them. Furthermore, methods based on composition may have limitations in optical applications that require transparency. There is a method to achieve smoothness by laminating a polyester with improved composition with a flat layer by co-extrusion, but there are problems with the composition mentioned above, as well as shape transfer of polyester with improved composition onto the flat layer. There are other problems. There is also a method of forming protrusions on the surface by stretching a film that has been surface-treated by solvent treatment, corona discharge treatment, etc., but there are various restrictions on the shape of the protrusions, and the slipperiness is often insufficient. In contrast to these methods, a method of forming fine and dense protrusions on the coating layer is attracting attention as a method for smoothing the film. As a method for forming protrusions on the coating layer, the method of incorporating fine inorganic particles is widely used to improve slipperiness and adhesion (blocking properties). A method of using a compound with characteristics of phase separation in the coating layer and elongation characteristics during coating and stretching as a coating agent in a method of stretching (hereinafter referred to as coating and stretching method) is attracting attention as a new method for producing smooth films. ing. For example, in JP-A-54-43017, gelatin is blended with polyester as a coating agent, and a polyester film with good slip properties is obtained by coating and stretching. Since then, JP-A-56-10455, JP-A-57-18254, and JP-A-58-62826 have been published.
A smooth film produced by coating and stretching has been proposed in Japanese Patent Publication No. These are applied to a film that has been uniaxially stretched vertically and then stretched in the horizontal direction, and the protrusion shape of the coating layer is long in the vertical direction, so the name of the protrusion shape is
It is described as a ``worm-like process'' or a ``mountain-like process'' (hereinafter abbreviated as a vertically long process). Furthermore, as a special type of vertically long protrusions, "discontinuous film-like protrusions" in which the surface of the base polyester film is exposed due to breakage of the coating layer have also been proposed. Furthermore, in order to improve slipperiness and the like, it has been proposed to use a silicone compound, a fluorine compound, a polyolefin compound, etc. in combination with particles or a longitudinal protrusion forming agent in a coating/stretching method. [Object of the Invention] The present inventors have previously developed a polyester film with excellent adhesiveness that has a coating layer made of polyurethane and polyester (Japanese Unexamined Patent Publication No. 78761/1983), or a coating layer made of acrylic resin and polyester. A polyester film with excellent adhesive properties (Japanese Patent Application Laid-open No. 124651/1982), a polyester film with excellent slipperiness and adhesive properties with a coating layer made of acrylic resin, silica sol, and/or a specific soluble resin Publication No. 60-61259, Japanese Patent Publication No. 1983
-63161, Japanese Unexamined Patent Publication No. 60-63162). An object of the present invention is to further improve the slip properties of these polyester films, and to provide a polyester film with improved antistatic properties and coating strength. [Structure of the Invention] The present inventors investigated particles or a specific anionic compound as a composition of polyurethane or acrylic resin, and found that the particles and a specific anionic compound, especially in the case of an ultra-flat base film. The present inventors have discovered that when a polyester film is produced by a coating and stretching method using a compound in combination, the slipperiness is improved, leading to the present invention. That is, the present invention provides an alkyl sulfonate and/or a polyester film on at least one side of the polyester film.
Alternatively, it is a polyester film obtained by applying a coating liquid consisting of an alkyl sulfate salt, particles, a polyurethane and/or acrylic resin having an anionic group, and, if necessary, a polyester having an anionic group, and then stretching the film. The polyester of the polyester film constituting the substrate in the present invention is polyethylene terephthalate in which 80 mol% of the constituent components are ethylene terephthalate, or polyethylene naphthalate in which 80 mol% or more of the constituent components are ethylene naphthalate. Examples of polyester components other than ethylene terephthalate and ethylene naphthalate include diethylene glycol, propylene glycol, neopentyl glycol, 1,4-butylene glycol, 1,4-cyclohexanedimethanol, polyethylene glycol, and polytetramethylene glycol. Diol components, dicarboxylic acid components such as isophthalic acid, 5-sodiosulfoisophthalic acid, adipic acid, sebacic acid and its ester-forming derivatives, oxycarboxylic acids such as oxybenzoic acid and its ester-forming derivatives, etc. can be used. Yes, but not limited to these. The polyester film constituting the substrate in the present invention may contain so-called additive particles or precipitated particles, a polyester having different properties from the polyester of the substrate, or a polymer other than polyester in order to form protrusions on the surface of the film. . The surface roughness of the base polyester film can be determined by a person skilled in the art who can select the type, size, and amount of the protrusion-forming agent depending on the required characteristics such as slipperiness and transparency of the product in which the polyester film of the present invention is used. This can be achieved using well-known methods. Compositions other than the protrusion-forming agent for the polyester film constituting the base may include antistatic agents, stabilizers, lubricants, colorants, light blocking agents, etc., depending on the required characteristics of the product in which the polyester film of the present invention is used. may contain. Orientation of the polyester film that constitutes the base,
Properties such as crystallinity, mechanical properties, and dimensional stability can be achieved by selecting film manufacturing conditions well known to those skilled in the art depending on the required properties of the product in which the polyester film of the present invention is used. The anionic group-containing polyurethane of the present invention not only serves as a binder for the alkyl sulfonate, alkyl sulfate salt, and particles, but also serves as a binder for the alkyl sulfonate, alkyl sulfuric acid ester salt, and particles, and also serves as a coating layer, vapor deposition layer, etc. on the coating layer of the polyester film of the present invention. In some cases, it exhibits the effect of improving adhesion. The anionic group-containing polyurethane used in the present invention is preferably water-soluble or water-dispersible.
Markomol.Chem., 98 133-165 (1981), Special Publication No. 42-24194, Special Publication No. 7720, No. 46-77, Special Publication No. 46-
No. 10193, Special Publication No. 49-37839, Japanese Patent Publication No. 123197-1977
No., JP-A-53-126058, JP-A-54-138098,
Polyurethanes known in JP-A-61-36314, JP-A-57-125048, etc., or polyurethanes similar thereto can be used. The main components of the polyurethane-forming component are polyisocyanates, polyols, chain extenders, crosslinkers, and the like. Examples of polyisocyanates include tolylene diisocyanate, phenylene diisocyanate,
Examples include 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate. Examples of polyols include polyoxyethylene glycol, polyoxypropylene glycol,
Examples include polyethers such as polyoxytetramethylene glycol, polyesters such as polyethylene adipate, polyethylene-butylene adipate, polycabrolactone, acrylic polyols, and castor oil. Examples of chain extenders or crosslinking agents include ethylene glycol, propylene glycol, butanediol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine,
Examples include diethylenetriamine, 4,4'-diaminediphenylmethane, 4,4'-diaminodicyclohexylmethane, and water. Polyurethane having an anionic group can be produced by using a compound having an anionic group as a polyurethane forming component such as a polyol, a polyisocyanate compound, or a chain extender, or by combining an unreacted isocyanate group of the produced polyurethane with a compound having an anionic group. It can be produced using a method in which a group having an active hydrogen of polyurethane is reacted with a compound having an anionic group, and the like. In the method of using a compound having an anionic group as a polyurethane forming component, for example, a compound obtained by a method of sulfonating an aromatic isocyanate compound, a diaminocarboxylic acid salt, a sulfuric acid ester salt of amino alcohols, etc. can be used. The method of reacting an unreacted isocyanate group of polyurethane with a compound having an anionic group is as follows:
For example, bisulfites, aminosulfonic acids and salts thereof, aminocarboxylic acids and salts thereof, sulfuric acid esters of amino alcohols and salts thereof, hydroxyacetic acid and salts thereof, etc. can be used. Examples of the compound having an anionic group to be reacted with the group having active hydrogen of polyurethane include dicarboxylic acid anhydride, tetracarboxylic acid anhydride,
From a three-membered ring indicating a salt type group or a group capable of forming a salt after ring opening, such as sultone, lactone, epoxycarboxylic acid, epoxysulfonic acid, 2,4-dioxo-oxazolidine, isatoic anhydride, hostone, carbyl sulfate, etc. A 7-membered cyclic compound can be used. In the case of polyester polyurethane, an anionic group can be introduced into the polyurethane by using a polyester having an anionic group. A polyester having an anionic group is one in which a compound having a sulfonic acid group or a carboxylic acid group is bonded to a polyester by copolymerization, graft polymerization, or the like. The polyurethane is preferably a resin comprising a polyol having a molecular weight of 300 to 20,000, a polyisocyanate, a chain extender having a reactive hydrogen atom, a group that reacts with an isocyanate group, and a compound having at least one anionic group. The anionic groups in polyurethane are -SO ₃ H, -
Lithium salts, sodium salts such as _OSO3H , COOH, etc.
Used as potassium salt, magnesium salt, or ammonium salt. The amount of anionic groups in polyurethane is 0.05% by weight to polyurethane having anionic groups.
8% by weight is preferred. If the amount of anionic groups is low, the water solubility or water dispersibility of polyurethane will be poor, and if the amount of anionic groups is high, the water resistance of the undercoat layer after coating will be poor, and the films will tend to stick to each other due to moisture absorption. It is. The acrylic resin in the present invention not only serves as a binder for the alkyl sulfonate, alkyl sulfate salt, and particles, but also when forming a coating layer, a printed layer, a vapor deposition layer, etc. on the coating layer of the polyester film of the present invention. It exhibits the effect of improving adhesion. The acrylic resin in the present invention is preferably water-soluble or water-dispersible, and preferably contains alkyl acrylate or alkyl methacrylate as a main component.
30 to 90 mol% of said components and 70 to 10 mol% of a vinyl monomer component copolymerizable with these components and having a functional group.
A water-soluble or water-dispersible resin containing is preferred. Vinyl monomers that can be copolymerized with alkyl acrylates or alkyl methacrylates and have a functional group can be used to impart hydrophilicity to the resin and improve its water dispersibility, or to bind the resin to a polyester film or to the undercoat layer. It is preferable to have a functional group that improves the adhesion with other coating layers or the affinity with the resin blended as a coating agent. Preferred functional groups include carboxyl groups or their salts, acid Anhydride groups, sulfonic acid groups, or salts thereof, amide groups, alkylolated amide groups, amino groups (including substituted amino groups) or alkylolated amino groups, or salts thereof, hydroxyl groups, epoxy groups, etc. It is.
Particularly preferred are carboxyl groups or salts thereof, acid anhydride groups, epoxy groups, and the like. Two or more types of these groups may be contained in the resin. The reason why it is preferable that the alkyl acrylate or alkyl methacrylate in the acrylic resin is 30 mol% or more is because of the coating formability, the strength of the coating film,
This is because blocking resistance becomes better. The reason why the alkyl acrylate or alkyl methacrylate content in the acrylic resin is preferably 90 mol% or less is that by introducing a compound having a specific functional group into the acrylic resin as a copolymerization component, it can be made water-soluble or water-dispersible. This is to make it easier to use and to stabilize its state over a long period of time.Furthermore, it improves the adhesion between the coating layer and the polyester film layer, and improves the strength, water resistance, and chemical resistance of the coating layer due to reactions within the coating layer. Furthermore, it is possible to improve the adhesion between the film of the present invention and other materials. Examples of alkyl groups in alkyl acrylates and alkyl methacrylates include methyl group, ethyl group, n-propyl group, isopropyl group, n-
Examples include butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, and cyclohexyl group. As the vinyl monomer having a functional group copolymerizable with alkyl acrylate or alkyl methacrylate, the following compounds having functional groups such as a reactive functional group, a self-crosslinking functional group, and a hydrophilic group can be used. Examples of compounds having a carboxyl group or a salt thereof, or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid,
Examples include crotonic acid, metal salts of these carboxylic acids with sodium, ammonium salts, maleic anhydride, etc. Compounds having sulfonic acid groups or their salts include vinyl sulfonic acid, styrene sulfonic acid,
Examples include metal salts and ammonium salts of these sulfonic acids with sodium and the like. Examples of compounds having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide,
Examples include methylolated acrylamide, methylolated methacrylamide, ureido vinyl ether, β-ureido isobutyl vinyl ether, and ureido ethyl acrylate. Examples of compounds having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether,
Dimethylaminoethyl methacrylate, dimethylaminoethyl vinyl ether, methylolated amino groups thereof, alkyl halides,
Examples include those converted into quaternary chlorides with dimethyl sulfate, sultone, etc. Examples of compounds having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate,
Examples include β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, and polypropylene glycol monomethacrylate. Examples of compounds having an epoxy group include glycidyl acrylate and glycidyl methacrylate. Furthermore, in addition to the above compounds, the following compounds may be used in combination. namely, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, maleic acid mono- or dialkyl esters, fumaric acid mono- or dialkyl esters,
Examples include, but are not limited to, itaconic acid mono- or dialkyl esters, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, and vinyl trimethoxysilane. The acrylic resin may contain a surfactant. However, when the ratio of acrylic resin to polyester resin is high, the low molecular weight surfactant contained in the acrylic resin becomes concentrated during the film forming process and accumulates at the interface between particles. It may migrate to the interface of the coating layer, causing problems in the mechanical strength, water resistance, and adhesion to the laminate of the coating layer. In such a case, a polymer obtained by so-called soap-free polymerization that does not contain a surfactant can be used. The method for producing acrylic resins that do not contain surfactants is published in "Water-soluble Polymers/Water-Dispersible Resins Comprehensive Technical Data Collection" No. 389, edited by Management Development Center Publishing Department, published by Management Development Center Publishing Department, January 1981. It is possible to use the methods shown in the lecture text (December 1982) titled "~Prospecting the future from the latest research results~ New developments in emulsions and future technical issues" sponsored by the Industrial Technology Research Institute. can. For example, use of oligomers or polymeric surfactants instead of low molecular weight surfactants, introduction of hydrophilic groups into polymers by using polymerization initiators such as potassium persulfate or ammonium persulfate, and monomers having hydrophilic groups. copolymerization, the use of reactive surfactants, and so-called shell-core polymers in which the composition of the inner and outer layers of dispersion particles are changed. It can be used as a manufacturing technology. In the present invention, the polyester having an anionic group is used as the base material of the polyurethane and/or acrylic resin in the present invention to improve coatability, adhesion and strength of the coated layer to the film, and to form the coated layer of the polyester film of the present invention. It may be used as necessary to improve the formability of the laminated material and the adhesion after formation. The polyester having an anionic group in the present invention is preferably water-soluble or water-dispersible, and the dicarboxylic acid component is
Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,5-naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, oxycarboxylic acids such as oxybenzoic acid, and their ester-forming properties. Derivatives and the like can be used. In the present invention, the glycol component of the polyester having an anionic group includes aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol, and triethylene glycol, and alicyclic glycols such as 1,4-cyclohexanedimethanol. glycol,
Aromatic diols such as p-xylene diol, poly(oxyalkylene) glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. can be used. The polyester having an anionic group in the present invention includes not only the saturated linear polyester comprising the above-mentioned ester-forming component, but also the polyester having an anionic group.
The polyester component may be a compound having more than one ester-forming component or a compound having a reactive unsaturated group. In the present invention, the anionic group of the polyester having an anionic group is a sulfonic acid, a carboxylic acid, or a salt thereof. These sulfonate and carboxylate salts include ammonium salts,
These are amine salts such as methylamine and ethanolamine, and metal salts such as lithium, sodium, potassium, and magnesium. As polyesters having sulfonic acid groups, Japanese Patent Publication No. 47-40873,
Polyesters known in JP-A-50-83497, JP-A-50-121336, JP-A-52-155640, etc. or polyesters similar thereto can be used. A method for introducing a sulfonic acid group into a polyester is to transesterify the polyester with a metal salt such as sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and its ester-forming derivatives or during the polymerization process. A method of sulfonating an unsaturated group of a polyester copolymerized with an ester-forming aliphatic unsaturated compound with a sulfonating agent such as sodium bisulfite or sodium metasulfite, a method of adding styrene sulfonate to There is a method of grafting methacryl sulfonate or the like onto polyester using a radical initiator or the like. Methods for introducing carboxylic acid groups into polyester include the method of reacting a dioxy compound having a carboxylic acid group with polyester as shown in JP-A-61-228030, and the method of reacting acrylates, methacrylates, etc. with radicals. There is a method of introducing it into polyester using an initiator or the like. The amount of anionic groups in the polyester is preferably in the range of 1% to 10% by weight based on the weight of the sulfonic acid groups or carboxylic acid groups based on the total polyester. If the amount of anionic groups in the polyester is less than 1% by weight, the solubility and dispersibility of the polyester in water will be insufficient;
If the amount is greater than % by weight, the water resistance of the coated layer after coating tends to decrease. In the present invention, the polyester having an anionic group includes a silicon group, a fluorinated alkyl group,
A modified material obtained by grafting a compound having a carbon double bond with an epoxy group, an amide group, etc. may also be used. The molecular weight of the anionic group-containing polyester that can be used in the present invention is preferably 5,000 to 50,000. As commercially available polyesters having anionic groups, products available from Dainippon Ink Chemical Co., Ltd., Nippon Gosei Co., Ltd., Toyobo Co., Ltd., Gyooh Kagaku Co., Ltd., Takamatsu Yushisha Co., Ltd., etc. can be used, but are not limited to these. The alkyl sulfonate or alkyl sulfate salt in the present invention is represented by the structural formula RSO ₃ M or ROSO ₃ M. Here R
preferably has 8 to 30 carbon atoms. When the number of carbon atoms is less than 8, the compatibility with the resin to be blended is poor, and the effect of improving slippage is often not effective, probably because the so-called blooming effect is small, and the effect of improving antistatic properties is also small. When the number of carbon atoms is greater than 30, the proportion of sulfonic acid groups effective in preventing static electricity decreases, so it is necessary to increase the amount of this compound, and in such cases, the polyester film of the present invention can be applied. The adhesion of the layer may be reduced. In the structural formula, R may have an aromatic group having a saturated aliphatic alkyl group, but is preferably a saturated aliphatic straight chain or branched alkyl group. In the structural formula, M is selected from an ammonium group and potassium metals Li, Na, and K, with Na being preferred. The proportion of the alkyl sulfonate or alkyl sulfate salt in the coating layer in the present invention is preferably 2 wt% to 30 wt%, more preferably 5 wt% to 20 wt%. If the amount of this compound is less than 2wt%, the slipperiness or antistatic effect will not be significant, and if it is more than 30wt%, the slipperiness or antistatic effect will not necessarily be further improved, and the polyester of the present invention The adhesion of the coating layer of the film deteriorates, and the film becomes sticky. The particles in the present invention may be inorganic particles, organic particles, organic/inorganic composite particles, or may have a hollow structure. Inorganic particles include silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc,
Examples include, but are not limited to, calcium carbonate, titanium oxide, barium salt, carbon, molybdenum sulfide, antimony oxide sol, and so-called conductive metal particles. Examples of organic particles that can be used include those obtained by crushing and classifying polymers, those obtained by dissolving in a solvent and mixing with a poor solvent to precipitate particles, and those obtained by growing and precipitating particles during the polymerization process. Commercially available organic particles include, but are not limited to, benzoguanamine, silicone, fluorine resin, styrene-acrylic resin, acrylic resin, epoxy resin, and nylon resin. Organic and inorganic composite particles can be, for example, silica sol and core coated with acrylic resin using a so-called seed polymerization method, or organic particles with an inorganic compound or metal compound precipitated on them. It is not limited to these. The particle size of the particles in the present invention is determined by the thickness of the coating layer,
Although it varies depending on the required film slipperiness, transparency, and recording accuracy in information recording applications, it is preferably 0.01μ to 5μ, more preferably 0.02μ to 1μ.
It is. If the particle size of the particles in the present invention is less than 0.01μ, it is often not effective in improving slipperiness.
If it is larger than 5μ, deterioration of transparency etc. may be observed. In the present invention, it is preferable to use particles with a narrow particle size distribution, since this makes it easier to control the surface shape of the coating layer. Recently, monodispersed particles have become available, and particles with different particle sizes may be combined to design a particle system with a particle size distribution depending on the application and used in the coating layer. The proportion of particles in the coating layer in the present invention is preferably 1% to 70% by weight, more preferably 2% to 60% by weight. If the amount of particles in the coating layer is less than 1% by weight, the effect of improving slipperiness will be small, especially if the base film is flat, and if it is more than 70% by weight, the strength of the coating may decrease. Depending on the type of particles of the present invention, due to the type of surface functional group or ionicity, polyurethane having an anionic group, polyester having an anionic group, acrylic resin, alkyl sulfonate, etc. of the present invention may be used. Agglomeration may occur with alkyl sulfate salts. In such cases, care should be taken in the order of mixing particles and other components, or protection may be introduced by introducing specific low-molecular compounds or polymers onto the particle surface through reaction or adsorption. Those that form a layer are preferred. The coating liquid used in the present invention includes methylol- or alkylol-based urea-based, melamine-based, and guanamine-based crosslinking agents to improve the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer. , acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compounds,
It may contain blocked polyisocyanates, silane coupling agents, titanium coupling agents, zirco-aluminate coupling agents, heat, peroxides, photoreactive vinyl compounds, photosensitive resins, and the like. Additionally, it may contain antifoaming agents, coating properties improvers, thickeners, antistatic agents, organic lubricants, antioxidants, ultraviolet absorbers, foaming agents, dyes, pigments, etc., as necessary. . Furthermore, the coating solution of the present invention may contain a polymer other than the polymer of the present invention in order to improve the properties of the coating solution or the coating layer. Methods for applying the above-mentioned coating liquid to polyester film include a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or other coating equipment as shown in "Coating Method" by Yuji Harasaki, published by Maki Shoten in 1979. A method in which a coating solution is applied to an unstretched polyester film using a polyester film and biaxially stretched sequentially or simultaneously; a method in which the coating solution is applied to a uniaxially stretched polyester film and further stretched in a direction perpendicular to the previous uniaxial stretching direction; Alternatively, there is a method in which a biaxially stretched polyester film is coated and further stretched in the horizontal and/or vertical directions. The above-mentioned stretching step is preferably carried out at 60-130°C, and the stretching ratio is at least 4 in terms of area ratio.
It is more than twice as much, preferably 6 to 20 times. The stretched film is heat treated at 150-250°C. Further, it is preferable that the material is relaxed by 0.2 to 20% in the longitudinal and transverse directions in the highest temperature zone of the heat treatment and/or in the cooling zone at the exit of the heat treatment. In particular, 2 to 6
Apply the coating solution to a uniaxially stretched polyester film that has been stretched twice, and dry it appropriately, or immediately coat the uniaxially stretched polyester film without drying at 80 to 130°C in a direction perpendicular to the previous stretching direction. A preferred method is to stretch the film to 6 times and heat treat it at 150 to 250°C for 1 to 600 seconds. According to this method, it is possible to dry the coated layer at the same time as stretching, and the thickness of the coated layer can be reduced according to the stretching ratio, and a film suitable as a polyester film base material can be produced at a relatively low cost. can. The coating liquid in the present invention may be applied to only one side of the polyester film, or may be applied to both sides. When the polyester film of the present invention is coated only on one side, a coating layer other than the coating liquid of the present invention can be formed on the opposite side as necessary to impart other properties to the polyester film of the present invention. In addition, in order to improve the applicability and adhesion of the coating agent to the film,
The film may be subjected to chemical treatment or electrical discharge treatment before coating. Furthermore, in order to improve the adhesion, coating properties, etc. of the biaxially stretched polyester film of the present invention to the coating layer, the coating layer may be subjected to a discharge treatment after the coating layer is formed. The polyester film coated with the coating solution of the present invention obtained as described above preferably has a thickness of 3 to 500μ, and the thickness of the coating layer preferably ranges from 0.01μ to 5μ. , more preferably in the range of 0.02μ to 1μ. If the thickness of the coating layer is less than 0.01 μm, it is difficult to obtain a uniform coating layer and uneven coating is likely to occur on the product. If it is thicker than 5 μm, the slipperiness decreases and handling of the film becomes difficult, which is not preferable. Hereinafter, the present invention will be explained based on examples.
In addition, evaluation in Examples is based on the following method. (1) Film haze Measured according to JIS K6714 using an integrating sphere turbidity meter NDH-20D (trade name) manufactured by Nippon Denshoku Industries. (2) Slip property The coefficient of friction between films was measured according to ASTM D1894/63. (3) Antistatic property A Charge decay property Using a static honest meter (product name) manufactured by Anato Shokai, the discharge electrode was placed at a height of 2 cm above the sample in an atmosphere of 23°C and 50% RH.
Apply a voltage of 10kV to charge the film,
Discharge is stopped after the amount of charge is saturated. Thereafter, the charge decay property of the sample is measured using an electrometer placed 2 cm above the sample, and the half-life is determined. 5 seconds or less Very good 5-30 seconds Good 30-600 seconds Fairly good 600 seconds or more Poor In addition, if the charge decay property of the sample charged by the above method is poor, the sample should be heated at 35℃ and 100%RH.
Blow air for 1 second and evaluate whether any charge remains (forced humidification method). B Surface resistivity 16008A (product name), a concentric circular electrode manufactured by Yokogawa-Heuret-Paccard with an inner electrode diameter of 50 mm and an outer electrode diameter of 70 mm, was installed on the sample in an atmosphere of 23°C and 50% RH, and a voltage of 100 V was applied. Apply voltage and use the company's high resistance meter 4329A (product name)
Measure the surface resistivity of the sample. (4) Workability When the film is slit and wound into a roll, check whether the appearance of the roll is good without any so-called dents or steps, and whether the film is charged with static electricity when unwound from the roll. The running properties of the film during the processing process were evaluated, including whether the film was free of defects and had good performance. (5) Paint film strength: Surface property measuring device manufactured by Shinto Kagaku Co., Ltd.
Using HEIDON-14 (product name), the load was varied on a 0.25 mm diameter saphire needle, and the scratching speed was 100.
Measured in mm/min. The load at which the coating layer peels off from the polyester base is determined by taking a surface photograph of the film after the scratch test using a microscope. Examples 1 to 4, Comparative Examples 1 to 5 Intrinsic viscosity containing 10 ppm of Thyroid 266 (trade name), a silica particle manufactured by Fuji Devison Co., Ltd.
0.66 polyethylene terephthalate 280℃~300
The mixture was melt extruded at a temperature of 0.degree. C. and cast onto a cooling drum using an electrostatic adhesion method to obtain an amorphous film with a thickness of 820 .mu.m. This film was stretched 3.3 times in the longitudinal direction at 95°C, each of the following coating solutions A to I was applied to one side of the film, and then stretched 3.3 times in the transverse direction at 110°C.
Stretched twice and heat treated at 210°C to reduce the thickness of the coating layer.
A biaxially stretched polyester film having a thickness of 0.08μ and a base film thickness of 75μ was obtained. Haze of this film,
Table 1 shows the coefficient of static friction, coating strength, charge attenuation, surface resistivity, and workability of the coated layer surface and the surface without the coated layer.
Shown below.

[Table] As seen in Table 1, polyurethane and/or
Alternatively, it can be seen that when the acrylic resin, alkyl sulfonate, and particles are used together, the slipperiness and antistatic properties of the polyester film are improved without deteriorating the transparency. The reason why alkyl sulfonate increases the strength of the coating film in the scratch test method is thought to be because it reduces the frictional resistance with the scratching needle, as it improves the coefficient of static friction. It will be done. That is, the polyester film of the present invention is
Useful for applications that require transparency, slipperiness, and antistatic properties. Coating liquids A to I were prepared by blending the following coating agents in the parts shown in Table 2.

【table】

[Effects and uses of the invention]

By providing a coating layer made of polyurethane or acrylic resin, the polyester film of the present invention not only has a surface with good adhesive properties, but also has excellent slipperiness and antistatic properties, and in some cases, transparency. Since the slipperiness is improved without degrading it, it can be used for various purposes including plate making, magnetic recording, vapor deposition, thermal transfer, etc.

Claims (1)

[Claims] 1 consisting of an alkyl sulfonate and/or alkyl sulfate salt and a polyurethane and/or acrylic resin having an anionic group on at least one side of the polyester film,
A polyester film coated with a coating solution containing fine particles and then stretched.