JP2015160396A - Laminate polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film that can be suitably used as a process film used in various processes, for example, process sheets for transferring such as simultaneous molding and transferring, for manufacturing a flexible printed wiring board, and for manufacturing a plastic sheet, and that can be particularly suitably used in a process where smoothness and less degradation in releasing property by heat in processing are required.SOLUTION: A laminate polyester film is provided, which has a coating layer formed from a coating liquid comprising a release agent and an isocyanate compound on at least one surface of a polyester film; and the laminate polyester film has a center line average roughness (Ra) of 8 nm or less on a surface of the coating layer.

Description

  The present invention relates to a release film, especially for applications requiring smoothness and heat resistance, for example, for transfer of molding simultaneous transfer, for manufacturing flexible printed wiring boards, for process paper for manufacturing plastic sheets, etc. The present invention relates to a release polyester film suitable as a process film used in various processes.

  Conventionally, polyester films represented by polyethylene terephthalate and polyethylene naphthalate have excellent mechanical properties, dimensional stability, flatness, heat resistance, chemical resistance, optical properties, etc., and cost performance. It is used for various purposes. When a polyester film is used as a release film, it has a drawback of poor practicality because of its insufficient release properties for various resins and adhesives. For this reason, a method for laminating a releasable coating film on the surface of a polyester film has been studied. For example, a method of applying and laminating a long chain alkyl group-containing resin on the surface of a polyester film (Patent Document 1) has been proposed.

  Examples of applications that use polyester film as a release film include heat and pressure applied to the film during various processes, such as transfer for molding simultaneous transfer, manufacturing of flexible printed wiring plates, and process paper for manufacturing plastic sheets. There is something. When used for these heat-sensitive applications, the release film produced by the above-described method has poor film release properties, and the film cannot be removed smoothly, or the release agent is transferred to the other side. There is a need for a release film having excellent heat resistance.

  Further, when a polyester film having large unevenness is used as a process film, for example, when manufacturing a plastic sheet, the unevenness on the surface of the polyester film is transferred to the plastic, resulting in a product with poor smoothness.

JP 2002-240016 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is in various processes such as transfer for molding simultaneous transfer, for manufacturing a flexible printed wiring board, for process paper for manufacturing a plastic sheet, etc. An object of the present invention is to provide a smooth release polyester film with less deterioration of release properties due to heat during processing as a process film to be used.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the use of a laminated polyester film having a specific configuration can easily solve the above-described problems, and have completed the present invention.

  That is, the gist of the present invention is that at least one surface of a polyester film has a coating layer formed from a coating solution containing a release agent and an isocyanate compound, and the center line average roughness (Ra) of the coating layer surface. Is in a laminated polyester film characterized by being 8 nm or less.

  According to the laminated polyester film of the present invention, when used as a film for various processes such as for production of an antireflection film for transfer, the heat resistance is high, and smoothness with little deterioration of releasability due to heat during processing. A release polyester film can be provided, and its industrial value is high.

  The polyester film constituting the laminated polyester film in the present invention may have a single layer structure or a multilayer structure, and may have four or more layers as long as it does not exceed the gist of the present invention other than a two-layer or three-layer structure. It may be a multilayer, and is not particularly limited.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyester includes polyethylene terephthalate and the like. On the other hand, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid, etc.), etc. 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexane dimethanol, neopentyl glycol, is mentioned.

  There is no restriction | limiting in particular as a polymerization catalyst of polyester, A conventionally well-known compound can be used, For example, an antimony compound, a titanium compound, a germanium compound, a manganese compound, an aluminum compound, a magnesium compound, a calcium compound etc. are mentioned. Among these, titanium compounds and germanium compounds have high catalytic activity and can be polymerized in a small amount, and since the amount of metal remaining in the film is small, it is difficult to become a foreign substance and to form unevenness on the film surface. Therefore, it is preferable. Furthermore, since a germanium compound is expensive, it is more preferable to use a titanium compound.

  In the case of polyester using a titanium compound, the titanium element content is preferably 50 ppm or less, more preferably 1 to 30 ppm, and still more preferably 2 to 20 ppm. If the content of the titanium compound is too high, the polyester may be deteriorated in the process of melt-extruding the polyester, resulting in a strong yellowish film. If the content is too low, the polymerization efficiency is poor and the cost is low. In some cases, a film having a sufficient strength or a sufficient strength cannot be obtained. Moreover, when using the polyester by a titanium compound, it is preferable to use a phosphorus compound in order to reduce the activity of a titanium compound for the purpose of suppressing deterioration in the step of melt extrusion. As the phosphorus compound, orthophosphoric acid is preferable in view of the productivity and thermal stability of the polyester. The phosphorus element content is preferably in the range of 1 to 300 ppm, more preferably 3 to 200 ppm, and still more preferably 5 to 100 ppm with respect to the amount of polyester to be melt-extruded. If the content of the phosphorus compound is too large, it may cause gelation or foreign matter. If the content is too small, the activity of the titanium compound cannot be lowered sufficiently, and the yellowish It may be a film.

  In the present invention, it is an essential requirement that the center line average roughness Ra of the release layer surface of the polyester film is 8 nm or less.

  When a polyester film with a large surface irregularity is used as, for example, a film for a process during the production of a plastic sheet, the irregularity on the surface of the polyester film is transferred to the plastic, resulting in a product with a poor appearance, but the center line average roughness By using the surface of the polyester film with (Ra) of 8 nm or less, this problem can be suppressed.

  In the present invention, it is an essential requirement that the center line average roughness (Ra) of the coating layer surface is 8 nm or less, preferably 6 nm or less, more preferably 4 nm or less, and further preferably 3 nm or less. As the center line average roughness Ra is smaller, there is less unevenness transfer, and a good sheet can be produced.

  In the polyester layer of the film of the present invention, it is preferable to blend particles mainly for the purpose of imparting slipperiness and preventing scratches in each step. When there are no particles, or when there are few particles, the transparency of the film will be high and a good film will be obtained, but the slipperiness may be insufficient, so the film is easily scratched, and in the coating layer In some cases, it is necessary to improve the slipping property by adding particles. When the particles are blended, the kind of the particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples include, for example, a styrene resin, an acrylic resin, a urea resin, and phenol. Examples thereof include organic particles such as resin, epoxy resin, and benzoguanamine resin, and inorganic particles such as calcium carbonate, aluminum oxide, silica, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, and titanium oxide. From the viewpoint of good transparency, organic particles are preferable, and styrene resins and acrylic resins are more preferable. Further, from the viewpoint of improving the hardness of the film, a metal oxide is preferable, and aluminum oxide is more preferable in consideration of transparency and handleability. In addition, it is also possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed during the polyester production process.

  The organic particles described above may contain a metal compound or a silicon compound in order to improve the dispersibility of the particles, the affinity with polyester, and the like. Examples of the metal compound include an aluminum compound, a titanium compound, a zirconium compound, and an yttrium compound. Particularly, oxides of these metal compounds are preferable, and aluminum oxide and zirconium oxide are particularly preferable. Similarly, the silicon compound is preferably a silicon oxide compound.

  The organic particles are preferably a crosslinked type from the viewpoint of heat resistance. Examples of the crosslinkable compound include divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and the like, and divinylbenzene is particularly preferable from the viewpoint of excellent strength.

  The most preferred form of organic particles is a crosslinkable organic particle, for example, a copolymer of styrene or (meth) acrylate and divinylbenzene, such as a copolymer of styrene and divinylbenzene, and as a dispersant, It contains aluminum oxide or zirconium oxide.

In the case where particles are contained in the polyester film, the structure is preferably three or more layers from the viewpoint of ensuring transparency without deteriorating the slipperiness, and further considering the ease of production, it is a three-layer structure. Is more preferable, and the structure containing the particles in the outermost layer is optimal.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, although the average particle diameter of the particle | grains to be used also depends on the thickness of the layer containing particle | grains, Preferably it is 3.0 micrometers or less, More preferably, it is 0.01-2.5 micrometers, More preferably, it is 0.02-2. It is 0 μm, particularly preferably in the range of 0.03 to 0.5 μm. By using the above range, for example, when used for molding a plastic sheet, a sheet with less unevenness due to transfer of the film surface shape can be obtained.

  The content of the particles depends on the average particle size of the particles. When the average particle diameter of the particles is larger than 1.0 μm, the polyester film layer containing the particles preferably has a concentration of 3000 ppm or less, more preferably 50 to 1000 ppm, and still more preferably 100 to 200 ppm. Moreover, when the average particle diameter of particle | grains is 1.0 micrometer or less, in the layer of the polyester film containing particle | grains, Preferably it is 8000 ppm or less, More preferably, it is 100-5000 ppm or less, More preferably, it is 300-4000 ppm or less. By making it into said range, it can be set as the film which is excellent in handleability and has few unevenness | corrugations.

  The thickness of the polyester film layer containing the particles depends on the average particle size and content of the particles, but is preferably in the range of 0.5 to 125 μm, more preferably 1 to 10 μm, and still more preferably 1 to 5 μm. . By making it into said range, drop-off | omission of particle | grains can be prevented and it can be set as a smooth film.

  The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  The thickness of the polyester film in the present invention is not particularly limited as long as it can be formed as a film, but it is preferably from 5 to 300 μm, more preferably from the viewpoint of mechanical strength, handling properties and productivity. Is preferably in the range of 10 to 125 μm.

  As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, when producing a biaxially stretched polyester film, first, the polyester raw material described above is melt-extruded from a die using an extruder, and the molten sheet is cooled and solidified with a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in the direction perpendicular to the first-stage stretching direction at usually 70 to 170 ° C. and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, a method of obtaining a biaxially oriented film by performing heat treatment at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% can be mentioned. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the present invention, the simultaneous biaxial stretching method can be adopted for the production of the polyester film constituting the laminated polyester film. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature controlled normally at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 270 ° C. under tension or relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.

  Next, formation of the coating layer which comprises the laminated polyester film in this invention is demonstrated. Regarding the coating layer, it may be provided by in-line coating which treats the film surface during the process of forming a polyester film, or offline coating which is applied outside the system on a once produced film may be adopted. More preferably, it is formed by in-line coating.

  In-line coating is a method of coating within the process of manufacturing a polyester film, and specifically, a method of coating at any stage from melt extrusion of a polyester to heat setting after stretching and winding up. Usually, it is coated on any of an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, and a film after heat setting and before winding. Although not limited to the following, for example, in sequential biaxial stretching, a method of stretching in the transverse direction after coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) is particularly excellent. According to such a method, film formation and coating layer formation can be performed at the same time, so there is an advantage in manufacturing cost. In addition, in order to perform stretching after coating, the thickness of the coating layer can be changed by the stretching ratio. Compared to offline coating, thin film coating can be performed more easily. Further, by providing the coating layer on the film before stretching, the coating layer can be stretched together with the base film, whereby the coating layer can be firmly adhered to the base film. Furthermore, in the production of a biaxially stretched polyester film, the film can be restrained in the longitudinal and lateral directions by stretching while gripping the film end with a clip, etc. High temperature can be applied while maintaining the properties. Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the coating layer can be improved, and the coating layer and the base film can be more firmly adhered to each other. Furthermore, it can be set as a firm coating layer, and the performance and durability of the coating layer can be improved.

  In the present invention, it is an essential requirement to have a coating layer formed from a coating solution containing a release agent and an isocyanate compound.

  The coating layer in the present invention has a release performance suitable as a process film used in various processes such as transfer for molding simultaneous transfer, for manufacturing flexible printed wiring boards, for process paper for manufacturing plastic sheets, etc. It is provided in order to improve.

  The release agent used for forming the coating layer of the film of the present invention is used for improving the release property of the film, and is not particularly limited, and a conventionally known release agent can be used. Examples thereof include long-chain alkyl compounds, waxes, fluorine compounds, and silicone compounds. Among these, a long-chain alkyl compound is preferable from the viewpoint of little contamination and excellent releasability. These release agents may be used alone or in combination.

  The long-chain alkyl compound is a compound having a linear or branched alkyl group having usually 6 or more, preferably 8 or more, more preferably 12 or more carbon atoms. Examples of the alkyl group include hexyl group, octyl group, decyl group, lauryl group, octadecyl group, and behenyl group. Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing quaternary ammonium salts. . In view of heat resistance and contamination, a polymer compound is preferable. Further, from the viewpoint of effectively obtaining releasability, a polymer compound having a long-chain alkyl group in the side chain is more preferable.

The polymer compound having a long-chain alkyl group in the side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxyl group, and an acid anhydride.
Examples of the compound having such a reactive group include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a reactive group-containing polyester resin, and a reactive group-containing poly (meth) acrylic resin. Among these, polyvinyl alcohol is preferable in view of releasability and ease of handling.

  Examples of the compound having an alkyl group capable of reacting with the reactive group include, for example, long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, and behenyl isocyanate, hexyl chloride, and octyl chloride. Long chain alkyl group-containing acid chlorides such as decyl chloride, lauryl chloride, octadecyl chloride, and behenyl chloride, long chain alkyl group-containing amines, and long chain alkyl group-containing alcohols. Among these, long chain alkyl group-containing isocyanates are preferable, and octadecyl isocyanate is particularly preferable in consideration of releasability and ease of handling.

  In addition, a polymer compound having a long-chain alkyl group in the side chain can also be obtained by copolymerization of a long-chain alkyl (meth) acrylate polymer or a long-chain alkyl (meth) acrylate and another vinyl group-containing monomer. . Examples of the long-chain alkyl (meth) acrylate include hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, octadecyl (meth) acrylate, and behenyl (meth) acrylate. It is done.

  The wax is a wax selected from natural waxes, synthetic waxes, and blended waxes thereof. Natural waxes are plant waxes, animal waxes, mineral waxes, and petroleum waxes. Examples of plant waxes include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil. Animal waxes include beeswax, lanolin, and whale wax. Examples of the mineral wax include montan wax, ozokerite, and ceresin. Examples of petroleum wax include paraffin wax, microcrystalline wax, and petrolatum. Synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, and ketones. As synthetic hydrocarbons, Fischer-Tropsch wax (also known as Sazoir wax) and polyethylene wax are famous, but in addition to this, low molecular weight polymers (specifically, polymers having a viscosity number average molecular weight of 500 to 20000) Some of the following polymers are also included. That is, there are polypropylene, ethylene / acrylic acid copolymer, polyethylene glycol, polypropylene glycol, polyethylene glycol and polypropylene glycol block or graft conjugate. Examples of the modified wax include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivative herein is a compound obtained by any of purification, oxidation, esterification, saponification treatment, or a combination thereof. Hydrogenated waxes include hardened castor oil and hardened castor oil derivatives.

  The fluorine compound is a compound containing a fluorine atom in the compound. Organic fluorine compounds are preferably used in terms of the appearance of coating by in-line coating, and examples thereof include perfluoroalkyl group-containing compounds, polymers of olefin compounds containing fluorine atoms, and aromatic fluorine compounds such as fluorobenzene. . From the viewpoint of releasability, a compound having a perfluoroalkyl group is preferable. Furthermore, the compound containing the long-chain alkyl compound which is mentioned later can also be used for a fluorine compound.

  Examples of the compound having a perfluoroalkyl group include perfluoroalkyl (meth) acrylate, perfluoroalkylmethyl (meth) acrylate, 2-perfluoroalkylethyl (meth) acrylate, and 3-perfluoroalkylpropyl (meth) acrylate. Perfluoroalkyl group-containing (meth) acrylates such as 3-perfluoroalkyl-1-methylpropyl (meth) acrylate and 3-perfluoroalkyl-2-propenyl (meth) acrylate, and polymers thereof, and perfluoroalkylmethyl vinyl ether 2-perfluoroalkyl ethyl vinyl ether, 3-perfluoropropyl vinyl ether, 3-perfluoroalkyl-1-methylpropyl vinyl ether, 3-perfluoroalkyl-2-propenyl vinyl Perfluoroalkyl group-containing vinyl ether and polymers thereof such as ether, and the like. In view of heat resistance and contamination, a polymer is preferable. The polymer may be a single compound or a polymer of multiple compounds. From the viewpoint of releasability, the perfluoroalkyl group preferably has 3 to 11 carbon atoms. Further, it may be a polymer with a compound containing a long-chain alkyl compound as described later. Moreover, from a viewpoint of adhesiveness with a base material, it is more preferable that it is a polymer with vinyl chloride.

The silicone compound is a compound having a silicone structure in the molecule, and examples thereof include silicone emulsion, acrylic graft silicone, silicone graft acrylic, amino-modified silicone, perfluoroalkyl-modified silicone, and alkyl-modified silicone. In view of heat resistance and contamination, it is preferable to contain a curable silicone resin.
As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, and an electron beam curable type can be used.

The isocyanate compound used for forming the coating layer is a compound having an isocyanate derivative structure typified by a blocked isocyanate having a structure in which the isocyanate group of the isocyanate compound as a precursor is protected with a blocking agent. . Examples of the isocyanate include aliphatic isocyanate compounds, alicyclic isocyanate compounds, and aromatic isocyanate compounds. These isocyanate compounds are more preferably compounds having a plurality of isocyanate groups, that is, polyisocyanate compounds, from the viewpoint that they can be reacted to a higher degree and can improve the heat resistance of the release layer. Further, when an aqueous coating solution is used, it is more preferably a blocked isocyanate.

  Examples of the aliphatic polyisocyanate compound are derived from aliphatic diisocyanates such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-diisocyanatohexane, and lysine diisocyanate. Polyisocyanate compounds, lysine triisocyanate, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, bis (2-isocyanatoethyl) 2-isocyanatoglutarate, or compounds derived from these isocyanate compounds be able to. Of these, hexamethylene diisocyanate is preferred because of its industrial availability.

  Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate (1,3-bis (isocyanatomethyl) -cyclohexane, 4,4′-dicyclohexylmethane diisocyanate, norbornene diisocyanate, hydrogenated xylylene diisocyanate, or these isocyanates. Examples include compounds derived from compounds, etc. Among them, isophorone diisocyanate is preferred from the viewpoint of weather resistance and industrial availability.

  Examples of the aromatic polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, or these isocyanate compounds. A compound etc. can be mentioned.

  Among these polyisocyanate compounds, aliphatic polyisocyanate compounds and alicyclic polyisocyanate compounds are preferable because of excellent weather resistance. Furthermore, among aliphatic polyisocyanate compounds, aliphatic polyisocyanate compounds derived from aliphatic diisocyanates are preferred. Among these, hexamethylene diisocyanate is particularly preferable. Moreover, these isocyanate compounds may be used independently and may use 2 or more types together.

  The block polyisocyanate compound can be synthesized by reacting the isocyanate group of the polyisocyanate compound with a blocking agent.

Examples of the blocking agent include active methylene, oxime, pyrazole, alcohol, alkylphenol, phenol, mercaptan, acid amide, acid imide, imidazole, urea, amine, imine, heavy Examples thereof include a sulfite blocking agent. Among these, an active methylene blocking agent is preferable from the viewpoint that the peeling characteristics after heating are particularly difficult to change. Moreover, these blocking agents may use 2 or more types together.

  Examples of the active methylene-based blocking agent include isobutanoyl acetate, n-propanoyl acetate, n-butanoyl acetate, n-pentanoyl acetate, n-hexanoyl acetate, 2-ethylheptanoyl acetate, malonate, Examples thereof include acetoacetic acid esters and acetylacetone. Among them, isobutanoyl acetate, n-propanoyl acetate, n-butanoyl acetate, n-pentanoyl acetate, n-hexanoyl acetate, 2- Ethylheptanoyl acetate is preferable, more preferably isobutanoyl acetate, n-propanoyl acetate, n-pentanoyl acetate, and still more preferably isobutanoyl acetate. More specifically, examples of isobutanoyl acetate include methyl isobutanoyl acetate, ethyl isobutanoyl acetate, n-propyl isobutanoyl acetate, isopropyl isobutanoyl acetate, n-butyl isobutanoyl acetate, isobutyl isobutanoyl acetate, t-butyl isobutanoyl acetate, and isobutanoyl acetate. Examples include n-pentyl, n-hexyl isobutanoyl acetate, 2-ethylhexyl isobutanoyl acetate, phenyl isobutanoyl acetate, and benzyl isobutanoyl acetate. Of these, methyl isobutanoyl acetate and ethyl isobutanoyl acetate are preferred. Examples of n-propanoyl acetate include n-propanoyl methyl acetate, n-propanoyl ethyl acetate, n-propanoyl acetate isopropyl, n-propanoyl acetate n-butyl, n-propanoyl acetate t-butyl and the like. Among these, n-propanoyl methyl acetate and n-propanoyl ethyl acetate are preferable. Examples of n-pentanoyl acetate include n-pentanoyl methyl acetate, n-pentanoyl ethyl acetate, n-pentanoyl acetate isopropyl, n-pentanoyl acetate n-butyl, and n-pentanoyl acetate t-butyl. Among these, n-pentanoyl methyl acetate and n-pentanoyl ethyl acetate are preferable.

  In the active methylene blocked isocyanate compound used in the film of the present invention, the active methylene blocking agent shown above can be used alone or in combination of two or more. As the active methylene-based blocking agent used in combination, dimethyl malonate and diethyl malonate are preferable in that they are excellent in low-temperature curability and excellent in heat resistance of the formed release layer.

  Examples of the oxime blocking agent include formaldehyde oxime, acetoald oxime, acetone oxime, methyl ethyl ketoxime, and cyclohexanone oxime. Examples of the pyrazole-based blocking agent include pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like. Examples of the alcohol blocking agent include methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol and the like. It is done. Examples of the alkylphenol-based blocking agent include monoalkylphenols such as n-propylphenol, isopropylphenol, n-butylphenol, sec-butylphenol, t-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, and n-nonylphenol. Di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-t-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n- And dialkylphenols such as nonylphenol. Examples of the phenolic blocking agent include phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester, and the like. Examples of the mercaptan block agent include butyl mercaptan and dodecyl mercaptan. Examples of the acid amide blocking agent include acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam and the like. Examples of the acid imide blocking agent include succinimide and maleic imide. Examples of the imidazole blocking agent include imidazole and 2-methylimidazole. Examples of the urea blocking agent include urea, thiourea, ethylene urea, and the like. Examples of amine blocking agents include diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, and the like. Examples of the imine blocking agent include ethyleneimine and polyethyleneimine.

  The blocked isocyanate compound used in the film of the present invention preferably contains a hydrophilic part in order to enhance the compoundability in water-based paints. As a method for adding a hydrophilic part to the blocked isocyanate compound, for example, a precursor is used. The method of making the isocyanate group of an isocyanate compound and the hydrophilic compound which has active hydrogen react is mentioned.

  Examples of the hydrophilic compound having active hydrogen used in the blocked isocyanate compound used in the film of the present invention include a polyethylene glycol compound, a carboxylic acid-containing compound, a sulfonic acid-containing compound, and an amine-containing compound. These hydrophilic compounds may be used alone or in combination of two or more.

  Examples of the polyethylene glycol compound include monoalkoxy polyethylene glycol, polyethylene glycol, polyoxypropylene polyoxyethylene copolymer diol, polyoxypropylene polyoxyethylene block polymer diol, and the like. Monoalkoxy polyethylene glycols such as ethoxy polyethylene glycol are preferred.

  Examples of the carboxylic acid group-containing compound include monohydroxycarboxylic acid, dihydroxycarboxylic acid, and derivatives thereof. Among the carboxylic acid group-containing compounds, monohydroxycarboxylic acid or dihydroxycarboxylic acid is preferable, and monohydroxycarboxylic acid is more preferable.

  Specific examples of the carboxylic acid-containing compound include, for example, hydroxypivalic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, or polycaprolactone diol or polyether polyol using these as initiators. Derivatives, and salts thereof.

  Examples of the sulfonic acid group-containing compound include aminoethylsulfonic acid, ethylenediamino-propyl-β-ethylsulfonic acid, 1,3-propylenediamine-β-ethylsulfonic acid, N, N-bis (2-hydroxyethyl) -2. -Aminoethanesulfonic acid, and salts thereof.

  Examples of the amine-containing compound include a hydroxyl group-containing amino compound. Specific examples include dimethylethanolamine and diethylethanolamine.

  In addition, the block isocyanate compound used for this invention is used by the design which makes it react in a drying process or a film forming process, and improves the performance of a coating layer. It can be inferred that unreacted products of these crosslinking agents, compounds after the reaction, or mixtures thereof exist in the finished coating layer.

  In the formation of the coating layer of the film of the present invention, various polymers and crosslinking agents can be used in combination in order to improve the coating appearance and transparency and to control the release property.

  Specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches and the like. . Among these, polyester resin, acrylic resin, and urethane resin are preferable, and polyester resin is more preferable in terms of easy control of releasability.

  The polyester resin includes, for example, those composed of the following polyvalent carboxylic acid and polyvalent hydroxy compound as main constituent components. That is, as the polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6 -Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutar Acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and ester-forming derivatives thereof can be used. As the polyvalent hydroxy compound, ethylene Recall, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol , Neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol Polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like can be used. One or more compounds may be appropriately selected from these compounds, and a polyester resin may be synthesized by a conventional polycondensation reaction.

  The acrylic resin is a polymer composed of a polymerizable monomer including acrylic and methacrylic monomers. These may be either homopolymers or copolymers, and copolymers with polymerizable monomers other than acrylic and methacrylic monomers. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyester solution or a polyester dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer in a polyurethane solution or a polyurethane dispersion (sometimes a mixture of polymers) is also included. Similarly, a polymer (in some cases, a polymer mixture) obtained by polymerizing a polymerizable monomer in another polymer solution or dispersion is also included. Moreover, in order to improve adhesiveness more, it is also possible to contain a hydroxyl group and an amino group.

  The polymerizable monomer is not particularly limited, but particularly representative compounds include, for example, various carboxyl groups such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid. Monomers, and salts thereof; such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, monobutyl hydroxy itaconate Various hydroxyl group-containing monomers; various (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate; (Meth) acrylamide, Various nitrogen-containing compounds such as acetone acrylamide, N-methylol acrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, and various vinyls such as vinyl propionate Esters; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc .; phosphorus-containing vinyl monomers; various vinyl halides such as vinyl chloride and biridene chloride Various conjugated dienes such as butadiene.

  The urethane resin is a polymer compound having a urethane bond in the molecule. Usually, urethane resin is prepared by reaction of polyol and isocyanate. Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

Polycarbonate polyols are obtained from a polyhydric alcohol and a carbonate compound by a dealcoholization reaction. Examples of the polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane. Diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Diol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylol heptane and the like can be mentioned. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate. Examples of polycarbonate polyols obtained from these reactions include poly (1,6-hexylene) carbonate, poly (3- And methyl-1,5-pentylene) carbonate.

  Polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides. Product and polyhydric alcohol (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol 2-methyl-2-propyl-1 3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexane Diol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyl dialkanolamine, lactone diol, etc.).

  Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, and the like.

  Examples of the polyisocyanate compound used for obtaining the urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, α, α, α ′, α ′. -Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl Methanzi Cyanate, alicyclic diisocyanates such as isopropylidene dicyclohexyl diisocyanates. These may be used alone or in combination.

  A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Alternatively, a chain extender having two amino groups can be mainly used.

  Examples of the chain extender having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and esters such as neopentyl glycol hydroxypivalate. And glycols such as glycols. Examples of the chain extender having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3- Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliphatic diamines such as decane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isopropylidenecyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1, 3-Bisaminomethylcyclohexa And alicyclic diamines such as

  The urethane resin in the present invention may use a solvent as a medium, but preferably uses water as a medium. In order to disperse or dissolve the urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsification type in which a hydrophilic group is introduced into the urethane resin, and a water-soluble type. In particular, the self-emulsification type in which an ionic group is introduced into the structure of the urethane resin to form an ionomer is preferable because of excellent storage stability of the liquid and water resistance and transparency of the resulting coating layer. Examples of the ionic group to be introduced include various groups such as a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, quaternary ammonium salt, and the like, and a carboxyl group is preferable. As a method for introducing a carboxyl group into a urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a carboxyl group-containing resin as a copolymer component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as polyol, polyisocyanate, and chain extender. In particular, a method in which a desired amount of carboxyl groups is introduced using a carboxyl group-containing diol depending on the amount of this component charged is preferred. For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid and the like are copolymerized with a diol used for polymerization of a urethane resin. Can do. The carboxyl group is preferably in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali or the like. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a polyurethane resin, a carboxyl group from which a neutralizing agent is removed in a drying step after coating can be used as a crosslinking reaction point by another crosslinking agent. Thereby, it is possible to further improve the durability, solvent resistance, water resistance, blocking resistance, and the like of the obtained coating layer, as well as excellent stability in a liquid state before coating.

  Specific examples of the crosslinking agent include melamine compounds, epoxy compounds, carbodiimide compounds, oxazoline compounds, aziridine compounds, silane coupling compounds, and the like. Among these, melamine compounds, epoxy compounds, carbodiimide compounds, and oxazoline compounds are preferable, and melamine compounds are particularly preferable from the viewpoint of improving the coating strength.

  The melamine compound is a compound having a melamine skeleton in the compound. For example, an alkylolized melamine derivative, a compound partially or completely etherified by reacting an alcohol with an alkylolated melamine derivative, and these Mixtures can be used. As alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used. Moreover, as a melamine compound, either a monomer or a multimer more than a dimer may be sufficient, or a mixture thereof may be used. Further, a product obtained by co-condensing urea or the like with a part of melamine can be used, and a catalyst can be used to increase the reactivity of the melamine compound.

  Moreover, in the range which does not impair the main point of this invention, it is also possible to use particle | grains together for the purpose of the formation of the coating layer of the film of this invention for the purpose of the blocking property of a coating layer, slipperiness improvement, etc.

  Further, in the range not impairing the gist of the present invention, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, and an antioxidant are formed as necessary for forming the coating layer. It is also possible to use a foaming agent, a dye, a pigment and the like in combination.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the coating layer which comprises the laminated polyester film in this invention, a mold release agent is the range of 5-97 weight% normally, Preferably it is the range of 15-90 weight%, Furthermore, Preferably it is the range of 25-80 weight%. If the amount is less than 5% by weight, sufficient release performance may not be obtained. If the amount is more than 97% by weight, sufficient heat resistance may not be obtained because other components are small.

  As a ratio with respect to all the non-volatile components in the coating liquid which forms the coating layer which comprises the laminated polyester film in this invention, an isocyanate type compound is the range of 3-95 weight% normally, Preferably it is the range of 10-85 weight%, Furthermore, Preferably it is the range of 20 to 75 weight%. When it is out of the above range, the release performance after heating may not be sufficiently obtained.

  Analysis of the components in the coating layer can be performed by analysis of TOF-SIMS, ESCA, fluorescent X-rays, and the like, for example.

  When providing a coating layer by in-line coating, the above-mentioned series of compounds is applied as an aqueous solution or dispersion, and the coating solution adjusted to a solid content concentration of about 0.1 to 50% by weight as a guide is applied onto the polyester film. It is preferable to produce a laminated polyester film. Moreover, in the range which does not impair the main point of this invention, a small amount of organic solvents may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, and the like. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

  Regarding the laminated polyester film in the present invention, the thickness of the coating layer provided on the polyester film is preferably 0.003 to 1 μm, more preferably 0.005 to 0.5 μm, and still more preferably 0.01 to 0.2 μm. Range. When the film thickness exceeds 1 μm, the appearance and transparency may be deteriorated, and when the film thickness is less than 0.005 μm, sufficient releasability may not be obtained.

  Examples of the method for forming the coating layer of the present invention include gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, and impregnation. Conventionally known coating methods such as coat, kiss coat, spray coat, calendar coat, and extrusion coat can be used.

  In the present invention, the drying and curing conditions for forming the coating layer on the polyester film are not particularly limited. For example, when the coating layer is provided by off-line coating, it is usually 3 to 40 at 80 to 200 ° C. The heat treatment should be performed for 2 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

  On the other hand, when the coating layer is provided by in-line coating, it is usually preferable to perform heat treatment at 70 to 270 ° C. for 3 to 200 seconds as a guide.

  Further, irrespective of off-line coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination as required. The polyester film constituting the laminated polyester film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  The peeling force before heating of the polyester film of the present invention to the adhesive tape is preferably 2000 mN / cm or less, more preferably 1500 mN / cm or less, and still more preferably 1000 mN / cm or less. By setting the amount within the above range, the peeling operation is facilitated.

  The peel strength of the polyester film of the present invention after heating to the adhesive tape depends on the value of the peel strength before heating, but is preferably 2500 mN / cm or less, more preferably 2000 mN / cm or less, and even more preferably 1500 mN / cm or less. It is. By setting it in the above range, the material on the release layer can be peeled off well even after heat processing.

  In the present invention, it is preferable that the peeling force of the coating layer is little changed before and after heating. Usually, the peeling force tends to increase due to heating, and the smaller the increase, the easier it is to predict the peeling characteristics after heating from the peeling characteristics before heating, and the method of peeling work is the same as before heating. It becomes possible to adjust. The peel force before and after heating is compared, and the value of difference in heat peel force = (peel force after heating−peel force before heating) is preferably 2000 mN / cm or less, more preferably 1600 mN / cm or less. More preferably, it is 1200 mN / cm or less.

  The surface of a plastic sheet or the like produced by transfer using the polyester film of the present invention preferably has a center line average roughness Ra of 8 nm or less, more preferably 6 nm or less, and 4 nm or less. More preferably, it is particularly preferably 3 nm or less.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measurement method and evaluation method used in the present invention are as follows.

(1) Method for measuring the intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. And dissolved at 30 ° C.

(2) Measurement of average particle diameter (d50) The average particle diameter d50 is the average particle diameter of 50% in the equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type) manufactured by Shimadzu Corporation. It was.

(3) Method for measuring film thickness of coating layer The surface of the coating layer was dyed with RuO ₄ and embedded in an epoxy resin. Thereafter, the section prepared by ultramicrotomy stained with RuO _4, a coating layer cross-section was measured by using a TEM (Hitachi High Technologies Corporation H-7650, accelerating voltage 100 V).

(4) Center line average roughness (Ra) of film surface
Using a surface roughness measuring machine (SE-3F, manufactured by Kosaka Laboratory Ltd.), the measurement was performed at a measurement length of 2.5 mm according to JIS B0601-1994.

(5) Evaluation of Peeling Force before Heating of Release Film Adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation) was reciprocated once with a 2 kg rubber roller on the release layer surface of the sample film, and 1 at room temperature. The peel force after standing for a period of time was measured. For the peeling force, “Ezgraph” manufactured by Shimadzu Corporation was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.

(6) Evaluation of peel strength after heating of release film After pressure-reducing the adhesive tape ("No. 31B" manufactured by Nitto Denko Corporation) with a 2 kg rubber roller on the surface of the release layer of the sample film, 100 ° C Heated in an oven for 1 hr. Thereafter, the peel force after standing at room temperature for 1 hour was measured. For the peeling force, “Ezgraph” manufactured by Shimadzu Corporation was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.

(7) Transfer Product Smoothness Evaluation Method 85 parts by mass of dipentaerythritol hexaacrylate, 15 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate, photopolymerization initiator (trade name: Irgacure 184, Ciba Specialty Chemicals Co., Ltd.) 5 parts by mass of the mixed coating solution was applied, pressed from above on the surface of the coated layer of another laminated polyester film, and cured by irradiation with ultraviolet rays. Thereafter, the upper and lower polyester films were peeled off, and Ra on the surface of the obtained hard coat sheet was measured. In addition, when the peeling characteristic of a film is inadequate and a sheet | seat was not able to be peeled, the measurement is not implemented.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (A)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 30 ppm of ethyl acid phosphate with respect to the resulting polyester, and 100 ppm of magnesium acetate tetrahydrate with respect to the resulting polyester as the catalyst at 260 ° C. in a nitrogen atmosphere at 260 ° C. The reaction was allowed to proceed. Subsequently, 50 ppm of tetrabutyl titanate was added to the resulting polyester, the temperature was raised to 280 ° C. over 2 hours and 30 minutes, the pressure was reduced to 0.3 kPa in absolute pressure, and melt polycondensation was further carried out for 80 minutes. 0.63 polyester (A) was obtained.

<Method for producing polyester (B)>
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, and magnesium acetate tetrahydrate as a catalyst were subjected to an esterification reaction at 225 ° C. in a nitrogen atmosphere at 900 ppm with respect to the produced polyester. Subsequently, 3500 ppm of orthophosphoric acid was added to the produced polyester, and 70 ppm of germanium dioxide was added to the produced polyester. The temperature was raised to 280 ° C. over 2 hours and 30 minutes, and the pressure was reduced to an absolute pressure of 0.4 kPa. After 85 minutes of melt polycondensation, polyester (B) having an intrinsic viscosity of 0.64 was obtained.

<Method for producing polyester (C)>
In the production method of polyester (A), polyester (C) is obtained using the same method as the production method of polyester (A) except that 0.5% by weight of particles X is added to the produced polyester before melt polymerization. It was.
<Method for producing polyester (D)>
In the production method of polyester (A), polyester (D) is obtained using the same method as the production method of polyester (A) except that 1.0% by weight of particles Y is added to the produced polyester before melt polymerization. It was.

<Method for producing polyester (E)>
In the production method of polyester (A), polyester (E) is obtained using the same method as the production method of polyester (A) except that 1.5% by weight of particles Z is added to the produced polyester before melt polymerization. It was.
<Method for producing polyester (F)>
In the production method of polyester (A), polyester (F) is obtained using the same method as the production method of polyester (A) except that 0.5 wt% of particles W is added to the produced polyester before melt polymerization. It was.

Examples of particles contained in the polyester film are as follows.
Particle X: An organic particle having an average particle size of 1.4 μm, which is a copolymer of styrene and divinylbenzene and contains aluminum oxide.
Particle Y: calcium carbonate particles having an average particle diameter of 1.0 μm.
Particle Z: Aluminum oxide particles having an average particle diameter of 0.05 μm.
Particle W: Silica particles having an average particle diameter of 3.2 μm.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
・ Releasing agent (long-chain alkyl compound): (I)
To a four-necked flask, 200 parts of xylene and 600 parts of octadecyl isocyanate were added and heated with stirring. From the time when xylene began to reflux, 100 parts of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added in small portions over a period of about 2 hours. After the addition of polyvinyl alcohol, the reaction was completed by further refluxing for 2 hours. When the reaction mixture was cooled to about 80 ° C. and added to methanol, the reaction product was precipitated as a white precipitate. This precipitate was filtered off, added with 140 parts of xylene, and heated to dissolve completely. After repeating the operation of adding methanol again to precipitate several times, the precipitate was washed with methanol and dried and ground.

Active methylene block polyisocyanate: (II)
1000 parts of block polyisocyanate hexamethylene diisocyanate synthesized by the following method was stirred at 60 ° C., and 0.1 part of tetramethylammonium capryate was added as a catalyst. After 4 hours, 0.2 part of phosphoric acid was added to stop the reaction, and an isocyanurate type polyisocyanate composition was obtained. 100 parts of the obtained isocyanurate type polyisocyanate composition, 42.3 parts of methoxypolyethylene glycol having a number average molecular weight of 400, and 29.5 parts of propylene glycol monomethyl ether acetate were charged and maintained at 80 ° C. for 7 hours. Thereafter, the reaction solution temperature was kept at 60 ° C., 35.8 parts of methyl isobutanoyl acetate, 32.2 parts of diethyl malonate, and 0.88 part of 28% methanol solution of sodium methoxide were added and kept for 4 hours. Block polyisocyanate obtained by adding 58.9 parts of n-butanol and maintaining the reaction solution temperature at 80 ° C. for 2 hours, and then adding 0.86 part of 2-ethylhexyl acid phosphate.

・ Polyester resin: (IIIA)
Water dispersion of polyester resin copolymerized with the following composition: Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1,4-butanediol / diethylene glycol = 56/40/4 // 70/20/10 (mol%)
Acrylic resin: (IIIB) Aqueous dispersion of acrylic resin polymerized with the following composition: ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2 (% by weight) Emulsion polymer (emulsifier: anionic surfactant)
-Urethane resin: (IIIC)
Carboxylic acid water-dispersed polyester formed from isophorone diisocyanate unit / terephthalic acid unit / isophthalic acid unit / ethylene glycol unit / diethylene glycol unit / dimethylolpropanoic acid unit = 12/19/18/21/25/5 (mol%) Urethane resin

・ Hexamethoxymethylolmelamine: (IVA)
Epoxy compound: (IVB) polyglycerol polyglycidyl ether

Example 1:
Polyester (A), (B), (C) was mixed at a ratio of 92%, 5%, and 3%, respectively, and a mixed raw material (particle content 150 ppm) was used as a raw material for the outermost layer (surface layer). Cooling rolls set to 40 ° C., each of which is fed to two extruders, mixed at a ratio of 95% and 5% of (B), and fed to two extruders, respectively, melted at 285 ° C. The unstretched sheet was obtained by co-extrusion and cooling and solidifying with a layer configuration of two types and three layers (surface layer / intermediate layer / surface layer = 1: 35: 1 discharge amount). Next, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the difference in peripheral speed of the roll, and then the coating solution 1 shown in Table 1 below was applied to one side of the longitudinally stretched film, which was led to a tenter. The film was stretched 4.3 times at 110 ° C. in the transverse direction, heat treated at 235 ° C., then relaxed by 2% in the transverse direction, and having a release layer with a thickness (after drying) of 0.03 μm. A polyester film was obtained.

  When the obtained polyester film was evaluated, it was smooth, had good releasability before and after heating, and had little change in peeling force due to heating. Moreover, when the hard coat sheet created using the obtained polyester film was evaluated, a smooth sample was obtained. The properties of this film are shown in Table 3 below.

Examples 2-26:
In Example 1, the amount and thickness of the particles contained in the surface polyester film layer were changed to the film conditions shown in Table 1, and the coating composition was changed to the coating composition shown in Table 2 with Example 1. In the same manner, a polyester film was obtained. As shown in Table 3, the finished polyester film had good release properties and smoothness.

Comparative Example 1:
In Example 1, it manufactured like Example 1 except not providing an application layer, and obtained the polyester film. When the completed laminated polyester film was evaluated, it was as shown in Table 3 and was inferior in releasability.

Comparative Examples 2-6:
In Example 1, the amount and thickness of the particles contained in the surface polyester film layer were changed to the film conditions shown in Table 1, and the coating composition was changed to the coating composition shown in Table 2 with Example 1. In the same manner, a polyester film was obtained. When the finished laminated polyester film was evaluated, it was as shown in Table 3, and the release property before heating and after heating was inferior, the change in peel strength by heating was large, the smoothness was inferior, and obtained. The smoothness of the hard coat sheet was inferior.

  The release film of the present invention is particularly smooth as a process film used in various processes, for example, for transfer such as simultaneous molding transfer, for manufacturing flexible printed wiring boards, and for process paper for manufacturing plastic sheets. And can be suitably used in applications requiring heat resistance.

Claims (1)

It has a coating layer formed from a coating solution containing a release agent and an isocyanate compound on at least one surface of a polyester film, and the center line average roughness (Ra) of the coating layer surface is 8 nm or less. A laminated polyester film.