Support film for solution casting and method for manufacturing the same

Abstract

The present invention provides a film used as a support in the process of manufacturing resin films by the solution casting method, which exhibits excellent surface flatness, solvent resistance, and dimensional stability. The support film of the present invention has a structure in which a resin layer is provided on at least one surface of a polyester film. The resin layer contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more. The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. The dimensional change rate in the TD direction is 2.0% or less after heat treatment at 160°C for 15 minutes, and the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction is 0.5 to 1.5.

Description

[Technical Field]

[0001] The present invention relates to a film used as a support in the process of manufacturing a resin film by a solution casting method, and to a method for manufacturing the same. [Background technology]

[0002] The solution casting method, also known as the solution pouring method, is a method of producing a cast film by dissolving the resin to be made into a film in an organic solvent, pouring the resulting casting solution onto a flat support, and removing the solvent by heating and drying, then peeling the resulting thin film from the support. This method places minimal physical stress on the material. As a result, the resulting resin film is anisotropic, optically stable, and has extremely high thickness accuracy, making it widely used in the manufacture of high-performance materials.

[0003] The support material may be a metal drum or stainless steel belt, or it may be a plastic film or metal film. In particular, plastic films are suitable for obtaining good cast films because they have excellent transportability, flexibility, and operability. Among these, polyester films are preferably used because they have high mechanical strength, dimensional stability, transparency, and excellent coating properties for the casting liquid.

[0004] It is known that the polyester film used as the support may have a resin layer on its surface for the purpose of improving surface flatness and improving the release properties of the cast film (for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-208465 [Patent Document 2] Japanese Patent Publication No. 2023-145416 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the polyester film having a resin layer as described in Patent Document 1 has a difference in shrinkage rate in the MD direction and the TD direction. As a result, wrinkles may form in the polyester film under high-temperature conditions. When used as a support in the process of manufacturing resin films by the solution casting method, these wrinkles may be transferred to the resulting cast film, resulting in a decrease in surface flatness. Furthermore, the polyester film equipped with the resin layer described in Patent Document 2 has insufficient heat resistance, and its dimensional stability and release properties deteriorate under high-temperature conditions. Therefore, it is difficult to use a high-boiling point solvent that requires high-temperature heating and drying as the casting fluid, and the low solvent selectivity has been a problem.

[0007] Therefore, the object of the present invention is to provide a support film used as a support in the solution casting method that exhibits excellent surface flatness, solvent resistance (the property that the surface of the resin layer maintains excellent surface flatness even after being coated with an organic solvent and undergoing a high-temperature drying process for a certain period of time), and dimensional stability. Another object of the present invention is to provide a support film for use as a support in a solution casting method, which has excellent surface flatness, solvent resistance, dimensional stability, and coatability, as well as appropriate adhesion to the adherend and good release properties. Another object of the present invention is to provide a method for manufacturing the support film. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors of the present invention have found that a film in which the following resin layer is formed on a polyester film has excellent surface flatness, solvent resistance, and dimensional stability, and is suitable for use as a support in the process of manufacturing resin films by the solution casting method. The present invention was completed based on these findings.

[0009] In other words, the present invention relates to a film used as a support in the process of manufacturing a resin film by a solution casting method, The structure has a resin layer provided on at least one surface of the polyester film. The resin layer contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more. The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. The present invention provides a film in which the dimensional change rate in the TD direction is 2.0% or less after heat treatment at 160°C for 15 minutes, and the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) is 0.5 to 1.5.

[0010] The present invention also provides a film having an arithmetic mean roughness Sa of 20 nm or less on the resin layer surface.

[0011] The present invention also includes xylene at 0.5 g / m². 2 The present invention provides a film that is coated in such a manner, dried by heating at a temperature of 160°C for 20 seconds, and then has a residual adhesion rate of 70% or more as measured using an acrylic adhesive tape (manufactured by Nitto Denko Corporation, No. 31B).

[0012] The present invention also provides a film in which the arithmetic mean roughness Sa(1) of the resin layer surface after dropping xylene onto it, holding it in a 25°C environment for 30 minutes, and then drying it at 160°C for 5 minutes, and the arithmetic mean roughness Sa(2) of the resin layer surface before dropping xylene onto it, satisfy the following formula (a). [{Sa(1)-Sa(2)} / Sa(2)]×100≦20 (a)

[0013] The present invention also provides a film in which the crosslinking agent content is 1 to 40 parts by mass per 100 parts by mass of acid-modified polyolefin resin.

[0014] The present invention also provides the film wherein the crosslinking agent is an oxazoline group-containing compound.

[0015] The present invention also provides a laminate in which a cast film is laminated on the resin layer surface of the film.

[0016] The present invention also provides a method for manufacturing the film, comprising: Step 1 of applying the following composition for forming a resin layer onto at least one surface of a polyester film, drying it, and forming a laminate of a coating film and the polyester film; Step 2 of stretching the laminate; Step 3 of subjecting the stretched laminate to a relaxation treatment of 0.1 to 2.0%; and provides a method for manufacturing a film having the above steps. Composition for forming a resin layer: containing an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol having a saponification degree of 99.0% or less and an average polymerization degree of 1000 or more, and the content of the polyvinyl alcohol is 5 to 500 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin

Effects of the Invention

[0017] The support film of the present invention is excellent in surface flatness, solvent resistance, and dimensional stability of the resin layer surface, and has appropriate adhesion to an adherend and good releasability. Therefore, if the support film of the present invention is used as a support, a solution resin is applied to the resin layer surface and dried at a high temperature to form a cast film, the resin layer can hold the formed cast film with appropriate adhesion, and when peeling the cast film from the resin layer, it can be easily peeled off.

Modes for Carrying Out the Invention

[0018] [Support Film] The film of the present invention (hereinafter sometimes referred to as "support film" in this specification) has a structure in which a resin layer is laminated on at least one surface of a polyester film. The support film is used as a support in the process of manufacturing a resin film by the solution casting method.

[0019] <Resin layer> The resin layer of the support film of the present invention contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more.

[0020] From the viewpoint of suppressing costs while obtaining sufficient release properties, the thickness of the resin layer is preferably 0.01 to 5.0 μm, more preferably 0.03 to 3.0 μm, and even more preferably 0.05 to 1.0 μm.

[0021] (Acid-modified polyolefin resin) Acid-modified polyolefin resin is a resin obtained by reacting a polyolefin resin with an unsaturated monomer having an acidic functional group, and contains at least constituent units derived from olefins and constituent units derived from unsaturated monomers having an acidic functional group.

[0022] Examples of the olefins include chain-like olefins such as ethylene, propylene, 1-butene, 1-pentene, and 1-octene (preferably C 2-12 Alkenes, particularly preferably C 2-5 Alkenes include cyclic olefins such as cyclopentene, cyclohexene, cycloheptene, norbornene, 5-methyl-2-norbornene, and tetracyclododecene. These can be contained individually or in combination of two or more.

[0023] The aforementioned olefin preferably contains at least one selected from ethylene, propylene, butene, pentene, hexene, heptene, and octene, as it ensures appropriate adhesion and excellent release properties, prevents the cast film from peeling off when transporting the resin layer with the cast film laminated on it, and improves productivity. Therefore, it is particularly preferable to contain at least ethylene, and most preferably to contain ethylene and at least one α-olefin.

[0024] Therefore, as the polyolefin resin, an ethylene-α-olefin copolymer, which is a copolymer of ethylene and at least one type of α-olefin, is preferred.

[0025] The carbon number of the α-olefin is preferably 5 or more, more preferably 6 or more, and most preferably 8 or more. By making the carbon number of the α-olefin 5 or more, the flexibility of the ethylene-α-olefin copolymer is increased and the release properties of the adherend are improved. Examples of α-olefins with 5 or more carbon atoms include 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, etc. 5-15 α-olefins are one example. Among these, C1-hexene, 1-heptene, 1-octene, etc. are used to improve release properties. 5-10 α-olefins are preferred.

[0026] In ethylene-α-olefin copolymers, the preferred mass ratio of ethylene to α-olefin (ethylene / α-olefin) is 60 / 40 to 99 / 1. By setting the mass ratio (ethylene / α-olefin) within this range, it becomes easier to adjust the content of constituent units derived from unsaturated carboxylic acids, and the resulting acid-modified polyolefin resin can be easily dispersed in an aqueous medium. Furthermore, by setting the α-olefin component content in the ethylene-α-olefin copolymer to 1 to 40% by mass, the release properties from the adherend after high-temperature drying can be improved.

[0027] Polyolefin resins are preferably produced by copolymerizing monomer components containing olefins in the presence of a metallocene catalyst. This method allows for the production of a uniform polymer with a narrow molecular weight distribution and a low amount of low molecular weight components.

[0028] As ethylene-α-olefin copolymers in which the α-olefin has 5 or more carbon atoms, commercially available products such as the Esprene series from Sumitomo Chemical, the Tuffmer series from Mitsui Chemicals, and the Engage and Affinity series from Dow Chemical can also be used.

[0029] The polyolefin resin may also be a copolymer of the olefin and an ethylenically unsaturated compound having a side chain containing an oxygen atom. That is, the acid-modified polyolefin resin may contain constituent units derived from the olefin, constituent units derived from an unsaturated carboxylic acid, and constituent units derived from an ethylenically unsaturated compound having a side chain containing an oxygen atom.

[0030] When an acid-modified polyolefin resin contains structural units derived from ethylenically unsaturated compounds having side chains containing oxygen atoms, appropriate adhesion to the cast film laminated on the resin layer surface can be achieved. Therefore, even when transporting the resin layer with the cast film laminated on it, the cast film can be prevented from peeling off, thereby improving productivity.

[0031] Examples of ethylenically unsaturated compounds having a side chain containing an oxygen atom include (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include (meth)acrylic acid C 1-30 Alkyl esters are one example, and among them, (meth)acrylate C is particularly readily available. 1-20Alkyl esters are preferred. Specific examples of the (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate. These can be contained individually or in combination of two or more. In the present invention, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl acrylate, and octyl acrylate is preferred, with ethyl acrylate and / or butyl acrylate being more preferred, and ethyl acrylate being particularly preferred. Note that "(meth)acrylic acid~" includes "acrylic acid~" and "methacrylic acid~".

[0032] The polyolefin resin may further be copolymerized with other monomers, to the extent that it does not impair the effects of the present invention. Examples of other monomers include dienes, (meth)acrylonitrile, vinyl halides, pyrinidene halides, carbon monoxide, and sulfur disulfide. From the viewpoint of improving adhesion to the polyester film while enhancing release properties from the adherend, the content of constituent units derived from other monomers is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably none, per 100 parts by mass of the acid-modified polyolefin resin.

[0033] The weight-average molecular weight of the polyolefin resin is preferably 15,000 to 200,000, more preferably 15,000 to 150,000, and even more preferably 20,000 to 100,000. By using a polyolefin resin having a weight-average molecular weight within the above range, the content and molecular weight of unsaturated carboxylic acid-derived constituent units in the acid-modified polyolefin resin can be adjusted to the range described later, making it possible to obtain a desirable film.

[0034] As an unsaturated monomer having an acidic functional group, an unsaturated carboxylic acid (i.e., an unsaturated monomer having a carboxyl group) is preferred.

[0035] Examples of unsaturated carboxylic acids include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and crotonic acid; unsaturated dicarboxylic acids such as maleic anhydride, itaconic acid, fumaric acid, citraconic acid, mesaconic acid, and allyl succinic acid; unsaturated polycarboxylic acids such as aconitic acid and aconitic anhydride; half-esters of the aforementioned unsaturated dicarboxylic acids; and half-amides of the aforementioned unsaturated dicarboxylic acids. These can be contained individually or in combination of two or more.

[0036] Among the unsaturated carboxylic acids, at least one selected from acrylic acid, methacrylic acid, maleic acid, and maleic anhydride is preferred, particularly in terms of improving the dispersion stability of the acid-modified polyolefin resin in an aqueous medium.

[0037] The proportion of constituent units derived from unsaturated monomers (especially unsaturated carboxylic acids) having acidic functional groups in the total amount of acid-modified polyolefin resin is preferably 1 to 10% by mass, and more preferably 1 to 9% by mass. When the proportion of constituent units derived from unsaturated monomers (especially unsaturated carboxylic acids) having acidic functional groups is 1% by mass or more, the proportion of polar groups in the acid-modified polyolefin resin contained in the resin layer is appropriate, so it adheres well to the polyester film and can suppress the transfer of resin components to the adherend and the contamination of the adherend. Furthermore, it also has the effect of improving the dispersion stability of the acid-modified polyolefin resin in an aqueous medium. In addition, when the proportion of constituent units derived from unsaturated monomers (especially unsaturated carboxylic acids) having acidic functional groups is 10% by mass or less, it is possible to maintain high adhesion between the resin layer and the polyester film while improving the release properties between the resin layer and the adherend.

[0038] There are no particular restrictions on the copolymerization form of each component constituting the acid-modified polyolefin resin, and include random copolymerization, block copolymerization, and graft copolymerization (graft modification).

[0039] Acid-modified polyolefin resins can be produced, for example, by radical polymerization of a polyolefin resin and an unsaturated carboxylic acid.

[0040] The method for reacting the polyolefin resin with the unsaturated carboxylic acid is not particularly limited. For example, one method involves heating and melting the polyolefin resin and the unsaturated carboxylic acid above the melting point of the polyolefin resin in the presence of a radical generator, or dissolving the polyolefin resin and the unsaturated carboxylic acid in an organic solvent, and then heating and stirring in the presence of a radical generator to react them. The former method is preferred because it is easy to operate.

[0041] Examples of the radical generating agents include organic peroxides such as di-tert-butyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, tert-butylcumyl peroxide, benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, and di-tert-butyl diperphthalate, as well as azonitriles such as azobisisobutyronitrile. These can be appropriately selected and used depending on the reaction temperature.

[0042] The weight-average molecular weight of the acid-modified polyolefin resin is preferably 20,000 to 300,000, more preferably 20,000 to 200,000, and even more preferably 30,000 to 100,000, in terms of obtaining a coating film that exhibits excellent dispersibility in aqueous media, excellent coating properties, and excellent release properties from the adherend.

[0043] As acid-modified polyolefin resins, commercially available products such as "AN42115C," "N1050H," and "N1110H" from Mitsui Dow Polychemical Co., Ltd.'s Nucrel series, "A210K" from Nippon Polyethylene Co., Ltd.'s Rexpearl series, and "Yumex 1001" from Sanyo Chemical Industries, Ltd. can be used.

[0044] Furthermore, as acid-modified polyolefin resins containing ethylenically unsaturated compounds with oxygen-containing side chains, commercially available products such as "LX-4110," "HX-8210," "HX-8290," and "TX-8030" from Arkema's Bondine series (ethylene / ethyl acrylate / maleic anhydride copolymer) can be used.

[0045] Acid-modified polyolefin resins possess acidic functional groups and therefore react with crosslinking agents. By reacting with crosslinking agents to form a three-dimensional crosslinked structure, acid-modified polyolefin resins improve release properties, solvent resistance, and dimensional stability. Furthermore, improved cohesiveness suppresses the migration of resin components to the adherend during delamination.

[0046] (Crosslinking agent) As a crosslinking agent, it is preferable to use a compound having multiple functional groups in its molecule that are reactive with acidic functional groups (preferably carboxyl groups) contained in acid-modified polyolefin resin and / or hydroxyl groups contained in polyvinyl alcohol.

[0047] Examples of crosslinking agents include polyfunctional epoxy compounds, polyfunctional isocyanate compounds, polyfunctional aziridine compounds, carbodiimide group-containing compounds, oxazoline group-containing compounds, phenolic resins, and amino resins such as urea compounds, melamine resins, and benzoguanamine resins. These can be included individually or in combination of two or more.

[0048] In the present invention, at least one selected from polyfunctional isocyanate compounds, melamine resins, urea compounds, polyfunctional epoxy compounds, carbodiimide group-containing compounds, and oxazoline group-containing compounds is preferred as the crosslinking agent, at least one selected from carbodiimide group-containing compounds, polyfunctional epoxy compounds, and oxazoline group-containing compounds is more preferred, and an oxazoline group-containing compound is even more preferred. By using an oxazoline group-containing compound, the release properties from the adherend can be improved and the adhesion to the polyester film can be improved.

[0049] The oxazoline group-containing compound is not particularly limited as long as it has two or more oxazoline groups in its molecule.

[0050] Examples of oxazoline group-containing compounds include 2,2'-bis(2-oxazoline), 2,2'-ethylene-bis(4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis(2-oxazoline), and bis(2-oxazolinylcyclohexane) sulfide, which have an oxazoline group.

[0051] Examples of oxazoline group-containing compounds include oxazoline group-containing polymers obtained by polymerizing addition-polymerizable oxazolines such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline. Other monomers may be copolymerized into the oxazoline group-containing polymer as needed. The polymerization method for the oxazoline group-containing polymer is not particularly limited, and various known polymerization methods can be employed.

[0052] Among oxazoline group-containing compounds, oxazoline group-containing polymers are preferred due to their ease of handling. Commercially available oxazoline group-containing polymers include the Epocross series from Nippon Shokubai Co., Ltd. (water-soluble types "WS-300", "WS-500", "WS-700", and solid type "RPS-1005", etc.).

[0053] From the viewpoint of improving adhesion between the resin layer and the cast film after high-temperature treatment, improving release properties from the adherend, and improving solvent resistance, the crosslinking agent content is preferably 1 to 40 parts by mass per 100 parts by mass of acid-modified polyolefin resin. From the viewpoint of ensuring adequate adhesion with the cast film, the upper limit of the crosslinking agent content is more preferably 30 parts by mass, particularly preferably 20 parts by mass, and most preferably 15 parts by mass. From the viewpoint of improving solvent resistance, the lower limit of the crosslinking agent content is more preferably 3 parts by mass, even more preferably 5 parts by mass, particularly preferably 7 parts by mass, and most preferably 10 parts by mass.

[0054] In the resin layer of the support film of the present invention, the crosslinking agent reacts with acidic functional groups (e.g., carboxyl groups) in the acid-modified polyolefin resin to form a three-dimensional crosslinked structure. As a result, the cohesive force is improved, and the migration of the resin layer to the adherend after peeling can be suppressed. Furthermore, the resin layer has excellent adhesion to the polyester film, and when the resin layer is applied to the polyester film and then stretched, the resin layer stretches in accordance with the stretching of the polyester film, thereby suppressing the peeling of the resin layer from the polyester film. The resin layer also has excellent solvent resistance.

[0055] (Polyvinyl alcohol) The resin layer in the support film of the present invention contains, together with the acid-modified polyolefin resin, polyvinyl alcohol with a degree of saponification of 99.0% or less and an average degree of polymerization of 1000 or more. The presence of the polyvinyl alcohol dispersed in the resin layer improves the film-forming properties of the resin layer and suppresses the occurrence of coating defects such as coating gaps in the resin layer. By suppressing the occurrence of coating defects in the resin layer, peeling problems and transfer of the resin layer to the cast film are suppressed. Furthermore, it is possible to maintain the flatness of the resin layer even after the application of an organic solvent.

[0056] Polyvinyl alcohol includes vinyl ester polymers that have undergone complete or partial saponification. The water solubility of polyvinyl alcohol varies depending on the degree of saponification. In this invention, since the polyvinyl alcohol is used in combination with an acid-modified polyolefin resin dispersed in an aqueous medium, it is preferable that it has high water solubility, and therefore, a polyvinyl alcohol in which the vinyl ester polymer has undergone partial saponification is preferred.

[0057] The degree of saponification of polyvinyl alcohol is 99.0% or less. From the viewpoint of reducing the surface tension of the resin layer-forming composition to improve film-forming properties, improving solvent resistance, and suppressing the occurrence of coating defects such as coating gaps in the resin layer, thereby suppressing the occurrence of defects in the cast film and a decrease in release properties due to the transfer of these coating defects, a degree of saponification of 98.5% or less is preferred, a degree of 98.0% or less is more preferred, and a degree of 97.0% or less is even more preferred.

[0058] Furthermore, the degree of saponification of polyvinyl alcohol is preferably 90.0% or higher, more preferably 93.0% or higher, and even more preferably 95.0% or higher.

[0059] The average degree of polymerization of the polyvinyl alcohol is 1000 or higher, and more preferably 1500 or higher, from the viewpoint of improving solvent resistance, improving the flatness of the resin layer surface after solvent application, and improving the heat resistance of the resin layer. Furthermore, from the viewpoint of maintaining the flatness of the resin layer surface and suppressing the transfer of surface irregularities of the resin layer to the cast film, the average degree of polymerization of the polyvinyl alcohol is preferably 5000 or lower, more preferably 3000 or lower, and even more preferably 2500 or lower.

[0060] The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of acid-modified polyolefin resin. If the polyvinyl alcohol content is 5 parts by mass or more, excellent release properties from the cast film are obtained. If the polyvinyl alcohol content is 500 parts by mass or less, a good balance of moderate adhesion and release properties from the cast film is obtained. The upper limit of the polyvinyl alcohol content is preferably 300 parts by mass, more preferably 250 parts by mass, even more preferably 200 parts by mass, and particularly preferably 150 parts by mass. The lower limit of the polyvinyl alcohol content is preferably 20 parts by mass, more preferably 50 parts by mass.

[0061] Examples of commercially available polyvinyl alcohols that can be used include "JC-25", "JF-20", "JM-17L", and "JMR-10HH" from Nippon Vinegar Vinegar Co., Ltd.; "60-98" and "27-96" from Kuraray Co., Ltd., and "RS-2117" and "HR-3010" from Exceval; and "H-12" and "K-17C" from Denka Co., Ltd.

[0062] (Other ingredients) In addition to the acid-modified polyolefin resin, crosslinking agent, and polyvinyl alcohol described above, the resin layer of the support film of the present invention may contain one or more other components, as long as they do not impair the effects of the present invention.

[0063] Other components include, for example, organic or inorganic compounds such as wetting agents, defoaming agents, anti-wrinkle agents, antistatic agents, pigment dispersants, UV absorbers, pigments (e.g., titanium dioxide, zinc oxide, carbon black), dyes, catalysts, antioxidants, UV absorbers, and lubricants.

[0064] Wetting agents are compounds that have the function of improving leveling properties (ease of wetting) and defoaming properties by changing the rheological properties of the resin layer-forming composition. Examples include nonionic surfactants, acetylene-based surfactants, and amphiphilic oligomers.

[0065] As wetting agents, commercially available products such as "Surfinol PSA-336," "Surfinol 61," "Surfinol 420," "Surfinol 440," "Surfinol 485," "Orfin EXP.4200," "Orfin E1004," "Orfin E1006," "Orfin E1010," and "Orfin D-10" from Nisshin Chemical Industry Co., Ltd., and "Polyflow KL-900" from Kyoeisha Chemical Co., Ltd. can be used.

[0066] <Polyester film> The support film of the present invention contains a polyester film as a base material.

[0067] The polyester film contains a polyester resin as a resin component. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), poly(1,4-cyclohexylenedimethylene terephthalate), and polylactic acid (PLA), as well as polymers and copolymers. These can be contained individually or in combination of two or more.

[0068] The glass transition temperature (Tg) of the polyester resin is, for example, 50 to 120°C, preferably 60 to 100°C, and more preferably 65 to 90°C.

[0069] The melting point (Tm) of the polyester resin is, for example, 200 to 300°C, preferably 220 to 280°C.

[0070] In addition to the resin component, the polyester film may contain one or more known additives (such as fillers like silica particles, stabilizers, antistatic agents, plasticizers, lubricants, and antioxidants).

[0071] The surface of the polyester film may be treated with corona treatment, plasma treatment, ozone treatment, chemical treatment, solvent treatment, etc., to improve adhesion with the resin layer. In addition, the polyester film may have laminated layers such as silica or alumina, a barrier layer, an easy-adhesion layer, an antistatic layer, or an ultraviolet absorbing layer.

[0072] The polyester film may have a single-layer structure consisting of one type of layer, or it may have a multilayer structure consisting of two or more layers laminated together. Among these, the polyester film of the present invention is preferably one having a multilayer structure because the surface roughness of both surfaces can be controlled independently.

[0073] When a polyester film has a multilayer structure, it is preferable that the outer layer on the side where the resin layer is provided does not contain any substances that may roughen the surface of the outer layer (for example, fillers such as silica particles). This suppresses the bleeding out of substances that may roughen the surface of the outer layer, thereby improving the flatness of the outer layer surface and enhancing the adhesion between the polyester film and the resin layer.

[0074] The thickness of the polyester film is not particularly limited, but is preferably 12 to 200 μm, and more preferably 12 to 50 μm.

[0075] [Method for manufacturing support film] The above-mentioned support film can be manufactured, for example, through the following steps 1 to 3. Step 1: A process of applying a resin layer-forming composition to at least one side of a polyester film and drying it to form a laminate of the coating and the polyester film. Step 2: A step of stretching the laminate. Step 3: A process of applying a 0.1-2.0% relaxation treatment to the stretched laminate.

[0076] The resin layer forming composition contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a degree of saponification of 99.0% or less and an average degree of polymerization of 1000 or more, wherein the content of the polyvinyl alcohol is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin.

[0077] As a method for manufacturing the support film of the present invention, it is preferable to use an in-line method in which a resin layer forming composition is applied during the manufacturing process of a polyester film to form a coating film, the formed coating film is dried together with the polyester film, and further stretching and relaxation treatments are performed.

[0078] Furthermore, stretching methods include sequential biaxial stretching and simultaneous biaxial stretching. In the present invention, among these, the sequential biaxial stretching method is preferred for simplicity and operational reasons, in which case the resin layer forming composition is applied to a uniaxially stretched polyester film to form a coating, the formed coating is dried together with the polyester film, and then the film is stretched in a direction perpendicular to the uniaxial stretching direction and heat-set.

[0079] (Process 1) Step 1 is a step of coating a resin layer-forming composition onto at least one surface of a polyester film and drying it to form a laminate of the coating and the polyester film.

[0080] The resin layer-forming composition is preferably applied to the flat side of the polyester film. The resin layer-forming composition may also be applied to both sides of the polyester film.

[0081] As the polyester film to which the resin layer-forming composition is coated, an unstretched polyester film or a uniaxially stretched polyester film is preferred, and a uniaxially stretched polyester film is particularly preferred in terms of workability, with a polyester film uniaxially stretched in the MD direction being the most preferred.

[0082] Uniaxially stretched polyester film can be manufactured, for example, by the following method.

[0083] The polyester resin to be used as raw material is thoroughly dried, and the dried polyester resin is supplied to an extruder (for example, a single extruder). It is melted at a temperature above the temperature at which it becomes sufficiently plasticized and fluid, passed through a filter as needed, and then extruded into a sheet through a T-die. The sheet is then cooled in close contact with a cooling drum adjusted to a temperature below the glass transition temperature (Tg) of the polyester resin. This yields an unstretched polyester film.

[0084] Next, the obtained unstretched polyester film is uniaxially stretched. Uniaxial stretching is preferably performed by heating the unstretched polyester film using a heated roll or infrared light, etc., at a temperature of (Tg)°C to (Tg+40)°C based on the glass transition temperature (Tg) of the polyester resin, and utilizing the difference in peripheral speed of two or more rolls to uniaxially stretch it in either the MD direction or the TD direction (preferably in the MD direction) to a stretch ratio of about 2.5 to 4.0 times.

[0085] A uniaxially oriented polyester film having a single-layer structure can be obtained by the above manufacturing method. A uniaxially oriented polyester film having a multilayer structure can be manufactured by melting each of the polyester resins constituting multiple layers, extruding them using a multilayer die, laminating and fusing them, then solidifying and stretching, or by separately melting and extruding two or more polyester resins and solidifying them, then laminating and fusing the resulting films in an unstretched state or after stretching. In the present invention, the former method is preferred in terms of the simplicity of the process.

[0086] Examples of resin layer-forming compositions include compositions comprising a dispersion of acid-modified polyolefin resin in an organic solvent or aqueous medium, to which a crosslinking agent, polyvinyl alcohol, and optionally other components are blended; and compositions comprising a solution of acid-modified polyolefin resin dissolved in an organic solvent or aqueous medium, to which a crosslinking agent, polyvinyl alcohol, and optionally other components are blended.

[0087] Examples of the other components include organic or inorganic compounds such as wetting agents, defoaming agents, anti-wrinkle agents, antistatic agents, pigment dispersants, ultraviolet absorbers, pigments (e.g., titanium dioxide, zinc oxide, carbon black), dyes, catalysts, antioxidants, ultraviolet absorbers, and lubricants.

[0088] Among the compositions for forming a resin layer, a composition comprising an aqueous dispersion of an acid-modified polyolefin resin in an aqueous medium, blended with a crosslinking agent and polyvinyl alcohol, is preferred due to its ease of handling and excellent safety.

[0089] An aqueous medium is a liquid medium whose main component is water, and the water content is 2% by mass or more of the total volume of the liquid medium. In addition to water, the aqueous medium may contain an amphiphilic organic solvent for the purpose of promoting the dispersion of the acid-modified polyolefin resin. An amphiphilic organic solvent is an organic solvent in which the solubility of water at 20°C is 5% by mass or more (the solubility of water in organic solvents at 20°C is described in literature such as, for example, the "Solvent Handbook" (Kodansha Scientific, 10th edition, 1990)).

[0090] The particle size of the acid-modified polyolefin resin dispersed in the aqueous medium is preferably 1 μm or less, and more preferably 0.8 μm or less, from the viewpoint of stability when mixed with other components and storage stability after mixing. The number-average particle size of the acid-modified polyolefin resin is measured by dynamic light scattering.

[0091] The content of acid-modified polyolefin resin in the resin layer forming composition is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 5 to 35% by mass, from the viewpoint of maintaining an appropriate viscosity of the resin layer forming composition and forming a resin layer without coating defects.

[0092] The solid content concentration of the resin layer forming composition is not particularly limited, but in terms of maintaining the viscosity of the resin layer forming composition appropriately and improving the coating properties, it is preferably 1 to 60% by mass, more preferably 3 to 40% by mass, and even more preferably 3 to 35% by mass.

[0093] The method for dispersing the acid-modified polyolefin resin in an aqueous medium is not particularly limited, but examples include the method described in International Publication No. 02 / 055598.

[0094] The crosslinking agent content in the resin layer forming composition is preferably 1 to 40 parts by mass, more preferably 3 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass, per 100 parts by mass of acid-modified polyolefin resin.

[0095] The polyvinyl alcohol content in the resin layer-forming composition is 5 to 500 parts by mass per 100 parts by mass of acid-modified polyolefin resin. The upper limit of the polyvinyl alcohol content is preferably 300 parts by mass, more preferably 250 parts by mass, even more preferably 200 parts by mass, and particularly preferably 150 parts by mass. The lower limit of the polyvinyl alcohol content is preferably 20 parts by mass, more preferably 50 parts by mass.

[0096] The content of the wetting agent (total amount if two or more types are included) is preferably 0.05% by mass or more relative to the total amount of the resin layer forming composition. Furthermore, the content of the wetting agent is preferably 1.5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, relative to the total amount of the resin layer forming composition.

[0097] The resin layer-forming composition is preferably applied to the flat surface of the polyester film.

[0098] Known methods for applying a resin layer-forming composition to a polyester film include gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dipping coating, and brush coating. In the present invention, the gravure roll coating method is preferred among these.

[0099] After applying the resin layer-forming composition to the polyester film, an aging treatment may be performed in a controlled temperature environment to promote the reaction between the acid-modified polyolefin resin and the crosslinking agent contained in the applied resin layer-forming composition, and / or the reaction between the polyvinyl alcohol and the crosslinking agent. From the viewpoint of reducing damage to the polyester film, a relatively low aging treatment temperature is preferable, but from the viewpoint of ensuring the reaction proceeds sufficiently and rapidly, a high temperature is preferable. The aging treatment temperature is preferably 20 to 100°C, more preferably 30 to 70°C, and even more preferably 40 to 60°C.

[0100] (Process 2) Step 2 is a process of stretching the laminate of the coating film and polyester film obtained in Step 1.

[0101] If the polyester film constituting the laminate is a polyester film uniaxially stretched in the MD direction, the step is to stretch the laminate in the TD direction.

[0102] The stretching temperature in the TD direction is preferably set to begin at (Tg)°C to (Tg+40)°C, based on the glass transition temperature (Tg) of the polyester resin, and the maximum temperature is preferably set to (Tm-100)°C to (Tm-40)°C, based on the melting point (Tm) of the polyester resin. The stretching ratio in the TD direction is appropriately adjusted according to the required physical properties of the final film, but is preferably 3.5 times or more, more preferably 3.8 times or more, and even more preferably 4.0 times or more. After stretching in the TD direction, the film may be further stretched in the MD direction and / or TD direction to improve the elastic modulus and dimensional stability of the film.

[0103] (Step 3) Step 3 is a step of subjecting the stretched laminate to a relaxation treatment of 0.1 to 2.0%. The relaxation rate is, for example, 0.1 to 2.0%, preferably 0.1 to 1.0%, and more preferably 0.15 to 0.5%.

[0104] The relaxation treatment is preferably performed simultaneously with the heat setting treatment, and the heat setting treatment temperature is preferably (Tm-50)°C to (Tm-10)°C, based on the melting point (Tm) of the polyester resin. The relaxation treatment time is, for example, 1 to 60 seconds, preferably 1 to 30 seconds, and more preferably 1 to 10 seconds.

[0105] After the relaxation treatment, the support film of the present invention is obtained by cooling the film to a temperature below the glass transition temperature (Tg) of the polyester resin. The support film may be in the form of a roll.

[0106] [Characteristics of the support film] When the support film of the present invention is used as a support in the process of manufacturing a resin film by the solution casting method, it exhibits excellent release properties from the cast film formed on the resin layer.

[0107] Furthermore, when the support film is wound into a roll, it can suppress the migration of components from the resin layer to the back surface of the polyester film.

[0108] Furthermore, the support film has appropriate adhesion to the cast film formed on the resin layer, and the coefficient of dynamic friction between the resin layer and the cast film is, for example, 0.2 or more, preferably 0.3 or more. Because the support film of the present invention has the above coefficient of dynamic friction, even when the cast film is laminated on the support film and transported, it is possible to suppress the cast film from sliding off or shifting.

[0109] Furthermore, the coefficient of dynamic friction is preferably less than 0.6, and more preferably less than 0.5, from the viewpoint of suppressing scratches and other damage to the cast film when peeling it off.

[0110] The support film has excellent release properties, which can suppress the transfer of resin components to the adherend and the contamination of the adherend. Therefore, when an acrylic adhesive tape is attached to the support film and the attached acrylic adhesive tape is peeled off the support film, the residual adhesion rate of the acrylic adhesive tape is, for example, 70% or more, preferably 80% or more, and more preferably 85% or more.

[0111] Furthermore, the support film has excellent solvent resistance, and even when it comes into contact with the solvent contained in the casting solution, it can suppress changes in the surface condition of the resin layer. Therefore, when the support film is used as a support in the process of manufacturing a resin film by the solution casting method, it can suppress weakening of the resin layer and roughening of the surface of the resin layer due to the solvent, and it can suppress the transfer of resin components to the cast sheet.

[0112] Therefore, 0.5 g / m² of xylene as a solvent is added to the resin layer of the support film. 2The film is coated in such a manner, heated at 160°C for 20 seconds to dry, and then an acrylic adhesive tape is applied in the same manner as described above. The residual adhesion rate of the acrylic adhesive tape after peeling it off is, for example, 70% or more, preferably 80% or more, and more preferably 85% or more. Furthermore, the change in the residual adhesion rate of the acrylic adhesive tape due to contact of the support film with a solvent is, for example, 10% or less, preferably 5% or less, and more preferably 2% or less.

[0113] Furthermore, the support film exhibits excellent dimensional stability. The dimensional change rate in the TD direction of the support film after heat treatment at 160°C for 15 minutes is 2.0% or less, preferably 1.6% or less, and particularly preferably 1.2% or less. In addition, the dimensional change rate in the MD direction of the support film after heat treatment at 160°C for 15 minutes is preferably 2.0% or less, and more preferably 1.6% or less.

[0114] Furthermore, the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) of the support film after heat treatment at 160°C for 15 minutes is 0.5 to 1.5, preferably 0.6 to 1.3, and more preferably 0.7 to 1.2.

[0115] If the dimensional change rates in the TD direction and the MD direction, and the ratio (anisotropy) of the dimensional change rates in the MD direction and the TD direction are within the above range, then even if the casting liquid is applied to the support film and heated and dried, thermal deformation of the support film is suppressed, and thus wrinkles in the resulting cast film can be suppressed.

[0116] The surface roughness Sa of the resin layer constituting the support film is preferably 20 nm or less, more preferably 13 nm or less, even more preferably 10 nm or less, particularly preferably 9 nm or less, and most preferably 5 nm or less.

[0117] Furthermore, the surface roughness Sa of the polyester film surface of the support film is preferably 2 nm or more. When the surface roughness Sa is 2 nm or more, the slipperiness is improved, which prevents problems such as wrinkles forming when winding the support film into a roll, scratches forming when storing it in a roll, and the film surface becoming rough when unwinding due to blocking.

[0118] The maximum surface height Sz of the resin layer surface constituting the support film is preferably 1 μm or less, more preferably 0.5 μm or less, and most preferably 0.2 μm or less.

[0119] The surface condition of the support film is transferred to the cast film, and if the surface roughness Sa and maximum surface height Sz of the resin layer are within the aforementioned range, it is possible to suppress the occurrence of defects in the resulting cast film.

[0120] The support film exhibits excellent solvent resistance, and even after coating the resin layer surface with various organic solvents and drying, it can maintain a flat surface shape that remains unchanged from before coating. The change rate of the resin layer surface roughness Sa before and after solvent application, as determined by the method described in the examples, is, for example, 20% or less, and preferably 10% or less. Therefore, there is a wide range of organic solvents that can be used as the casting liquid.

[0121] Examples of organic solvents that can be used in the casting solution include alcohols such as ethanol and methanol; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate; ethers; aliphatic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as toluene and xylene; and glycols. These can be used individually or in combination of two or more.

[0122] As described above, the support film of the present invention has appropriate adhesion to the cast film and excellent release properties, dimensional stability, and solvent resistance, making it suitable for use as a support in the process of manufacturing cast films.

[0123] There are no particular restrictions on the resin used as the raw material for the cast film, but examples include (meth)acrylic resins, cycloolefin resins, polycarbonate resins, polyimide resins, LCP resins, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, triacetylcellulose, polyethersulfone, norbornene polymers, polyurethanes, polyvinyl chloride, and silicones. These can be used individually or in combination of two or more.

[0124] Commercially available (meth)acrylic resins include, for example, "Acrypet" from Mitsubishi Rayon Co., Ltd. and "Parapet" from Kuraray Co., Ltd. Commercially available cycloolefin resins include, for example, "ARTON" from JSR Corporation and "ZEONOR" from Nippon Zeon Co., Ltd. Commercially available polycarbonate resins include, for example, "Taflon" from Idemitsu Kosan Co., Ltd. and "Upilon" from Mitsubishi Gas Chemical Company, Inc. Commercially available polyimide resins include, for example, "Surprim" from Mitsubishi Gas Chemical Company, Inc. and "Aurum" from Mitsui Chemicals, Inc. Commercially available LCP resins include, for example, "Sumika Super" from Sumitomo Chemical Co., Ltd. and "Vecter" from Kuraray Co., Ltd.

[0125] The configurations and combinations thereof described above are merely examples, and additions, omissions, substitutions, and modifications to the configurations are permitted as appropriate, without departing from the spirit of the present invention. Furthermore, the present invention is not limited by its embodiments. [Examples]

[0126] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to these examples.

[0127] 1. Evaluation Method In this invention, various evaluations were performed using the following methods. (1) Amount of acid modification of acid-modified polyolefin resin Fourier transform infrared spectrophotometer (PerkinElmer, System-2000 type, resolution 4 cm -1 ) was used to perform infrared absorption spectrum analysis to determine the content of the structural units derived from unsaturated carboxylic acids, and this was taken as the amount of acid modification.

[0128] (2) Among the components constituting the acid-modified polyolefin resin, components other than unsaturated carboxylic acids Using orthodichlorobenzene (d4) as a solvent, at 120 °C, 1 H-NMR, 13 13C-NMR analysis (manufactured by Varian, 300 MHz) was performed to determine it. In addition, 13 In the 13C-NMR analysis, a gated decoupling method considering quantitative properties was used.

[0129] (3) The weight average molecular weight of the polyolefin resin used in the synthesis of the acid-modified polyolefin resin GPC analysis (manufactured by Shimadzu Corporation, LC-10AD type, columns used were two "KF-804L" and one "KF805L" manufactured by SHODEX connected in series) was used. Using tetrahydrofuran as an eluent, the measurement was carried out under the conditions of a flow rate of 1 ml / min and a temperature of 40 °C. Approximately 10 mg of the (co)polymer was dissolved in 5.5 mL of tetrahydrofuran and filtered through a PTFE membrane filter to obtain a measurement sample. The weight average molecular weight was determined from the calibration curve prepared with a polystyrene standard sample.

[0130] (4) The solid content concentration of the water-dispersed acid-modified polyolefin resin An appropriate amount of the water-dispersed acid-modified polyolefin resin was weighed, heated at 150 °C until the mass of the residue (solid content) reached a constant weight, and the mass of the residue (solid content) was weighed to determine the solid content concentration.

[0131] (5) Evaluation of the flatness of the resin layer surface (surface roughness Sa) For 10 locations on the resin layer surface of the support film, using a nano 3D optical interferometric measurement system VS1800 manufactured by Hitachi High-Tech Corporation, the surface roughness parameter Sa (arithmetic mean height, nm) was measured, and the average value was taken as the surface roughness Sa.

[0132] (6) Evaluation of solvent resistance of the resin layer surface (rate of change in Sa before and after solvent application) 0.5 mL of a solvent (water, ethanol, acetone, ethyl acetate, THF (tetrahydrofuran), cyclohexane, toluene, or xylene) was dropped onto the resin layer surface of the support film, held at room temperature for 30 minutes, and then dried for 5 minutes at a drying temperature approximately 20°C higher than the boiling point of each solvent under normal pressure. The drying temperatures for each solvent are as follows: Water: 120℃ Ethanol: 100℃ Acetone: 80℃ Ethyl acetate: 90℃ THF: 90℃ Cyclohexane: 100℃ Toluene: 130℃ Xylene: 160℃ Subsequently, the surface roughness Sa of the resin layer of the support film was determined using the same method as in "(5) Evaluation of flatness of the resin layer surface (surface roughness Sa)". Then, the rate of change of the resin layer surface roughness Sa before and after solvent dropping was calculated using the following formula. Note that a smaller rate of change of Sa indicates better solvent resistance. Sa change rate (%) = [(Sa after solvent addition - Sa before solvent addition) / Sa before solvent addition] × 100

[0133] (7) Evaluation of the release properties of the cast film An acrylic resin (Acripet VH-001, manufactured by Mitsubishi Chemical Corporation) dissolved in toluene was coated onto the resin layer surface of the support film. The coated surface was then heated at 150°C for 30 seconds to dry, forming a cast film approximately 2 μm thick. This resulted in a laminate in which the cast film was laminated onto the resin layer surface of the support film. A 100mm x 100mm test piece was cut from the obtained laminate. Adhesive tape (CT-18, manufactured by Nichiban Co., Ltd.) was then applied to the edge of the cast film surface of the test piece, and the peel strength was measured by peeling it off at a constant speed. The release properties were evaluated according to the following criteria. The peel strength was measured in a constant temperature room at 25°C. <Evaluation Criteria for Mold Release Properties> Excellent (◎): The cast film could be peeled off from the resin layer surface without tearing. Good (〇): The cast film was partially torn, but the entire cast film could be peeled off from the resin layer surface. Acceptable (△): The cast film broke midway, but by continuing to peel from the broken point, the entire cast film could be separated from the resin layer surface. Impossible (×): The cast film and resin layer were adhered together and could not be separated. Unacceptable (-): The adhesion between the cast film and the resin layer was weak, causing the cast film to slip off the resin layer.

[0134] (8) Evaluation of adhesion with cast film A laminate was obtained using the same method as described in "(7) Evaluation of release properties of cast film" above. The coefficient of dynamic friction between the cast film surface of the obtained laminate and the resin layer surface of the support film that does not have a cast film laminated on it was measured using a method in accordance with JIS K 7125, and the adhesion was evaluated according to the following criteria. <Evaluation Criteria for Adhesion> Good (○): 0.3 or higher and less than 0.5 Acceptable (△): 0.2 or more and less than 0.3, or 0.5 or more and less than 0.6 Unacceptable (×): Less than 0.2, or 0.6 or higher.

[0135] (9) Evaluation of the ability of the resin layer to prevent transfer of resin components to the adherend. Under normal temperature and pressure conditions, an acrylic adhesive tape was applied to the resin layer side of the support film using a rubber roller to prepare the sample. The obtained sample was sandwiched between metal plates / rubber plates / sample / rubber plate / metal plate in that order, and left for 24 hours under a 2kPa load and in an atmosphere of 70°C. Subsequently, the acrylic adhesive tape was peeled off the resin film from the sample from which the rubber and metal plates had been removed. The peel strength of the peeled acrylic adhesive tape was measured using the following method. Specifically, the peeled acrylic adhesive tape was attached to a stainless steel plate (SUS304, 1 mm thick) and left at room temperature for 20 hours under a load of 2 kPa. After that, the peel strength (F1) required to peel the acrylic adhesive tape from the stainless steel plate was measured. In addition, the peel strength (F0) of unused acrylic adhesive tape was measured using the same method as described above. Then, the residual adhesion rate (1) was calculated using the following formula, and the transfer prevention performance of the support film was evaluated. Note that a higher residual adhesion rate indicates superior transfer prevention performance. The residual adhesion rate of acrylic adhesive tape (1)(%) = (F1 / F0) × 100

[0136] The peel strength was measured in a constant temperature chamber at 25°C using a tensile testing machine (Intesco Corporation, Precision Universal Material Testing Machine Model 2020) under conditions of a peel angle of 180 degrees and a peel speed of 300 mm / min.

[0137] As the acrylic adhesive tape used, we used acrylic adhesive tape (No. 31B) manufactured by Nitto Denko Corporation, which has the following configuration. Composition: Acrylic adhesive layer / Polyester film laminate Tape thickness: 0.025mm Tape width: 50mm

[0138] (10) Evaluation of the solvent resistance of the resin layer and the ability to prevent the transfer of resin components to the substrate. Add xylene at a rate of 0.5 g / m² to the resin layer surface of the support film. 2 The material was coated in the manner described above and heated and dried at 160°C for 20 seconds. Subsequently, the peel strength (F2) was measured using the same method as for evaluating the transfer prevention of the resin components of the resin layer to the substrate in (9) above, and the residual adhesion rate (2) after xylene coating was calculated using the following formula. Note that the higher the residual adhesion rate, the better the solvent resistance and transfer prevention. The residual adhesion rate of acrylic adhesive tape (2) (%) = (F2 / F0) × 100 Furthermore, the residual adhesion rate (1) obtained in the evaluation of the transfer prevention properties of the resin components of the resin layer to the adherend described in (9) above was used as the residual adhesion rate before xylene coating, and the change in the residual adhesion rate due to xylene coating was calculated using the following formula. Change in residual adhesion rate due to xylene coating (%) = Residual adhesion rate (1) - Residual adhesion rate (2)

[0139] (11) Evaluation of dimensional stability For the support film, five samples measuring 10 cm in the MD direction and 1 cm in the TD direction were cut out to measure the dimensional change rate in the MD direction under conditions of 23°C and 50% RH. In addition, five samples measuring 10 cm in the TD direction and 1 cm in the MD direction were cut out to measure the dimensional change rate in the TD direction. The obtained samples were allowed to stand for 30 minutes at 23°C and 50% RH to conditioned humidity, and their lengths in the MD and TD directions (L1 (before heat treatment)) were measured. Subsequently, the sample was heat-treated at 160°C for 15 minutes using an oven, and then allowed to stand again at 23°C and 50% RH for 30 minutes to allow for humidity control. The lengths (L2 (after heat treatment)) in the MD and TD directions were then measured. For five samples, the dimensional change rates in the MD direction and TD direction were calculated using the following formulas, and the average values ​​were determined. Dimensional change rate (%) = (L1 - L2) / (L1) × 100 Furthermore, using the obtained dimensional change rates in the MD and TD directions, the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) was calculated.

[0140] (12) Evaluation of film-forming properties of resin layer Five 1000mm x 500mm samples were cut from the support film. In a darkroom, the obtained sample is illuminated with an LED light from the resin layer surface, and the 10mm depth of the resin layer is measured. 2 The presence or absence of coating defects was visually confirmed. The same procedure was performed five times, the average number of coating defects was calculated, and the film-forming properties were evaluated according to the following criteria. <Evaluation Criteria> Good (〇): No paint defects were found. Acceptable (△): Some areas with paint defects were found, but the number was two or less. Unacceptable (×): Coating defects were found, and there were three or more of them.

[0141] 2.Material <Acid-modified polyolefin resin> The acid-modified polyolefin resin used was obtained in the synthesis example described below.

[0142] Synthesis Example 1: Synthesis of acid-modified polyolefin resin E-1 and aqueous dispersion of acid-modified polyolefin resin E-1 80 g of ethylene-octene copolymer (ethylene / octene = 7 1 / 29 (mass ratio), weight-average molecular weight 68,000) was placed in a four-necked flask and heated and dissolved in 350 g of xylene under a nitrogen atmosphere. Then, while maintaining the system temperature at 140°C and stirring, 30 g of maleic anhydride as an unsaturated carboxylic acid and 5 g of di-t-butyl peroxide as a radical generator were added over 2 hours each, and the reaction was continued for 6 hours. After the reaction was complete, the resulting reaction product was placed in a large amount of acetone to precipitate the resin. This resin was further washed several times with acetone to remove unreacted maleic anhydride, and then dried under reduced pressure to obtain acid-modified polyolefin resin E-1 (acid modification amount 4.1% by mass).

[0143] Using a stirrer equipped with a heater and a sealed, pressure-resistant 1L glass container, 30g of the obtained acid-modified polyolefin resin E-1, 100g of THF, 18g of triethylamine, and 252g of distilled water were charged into the glass container, and the mixture was stirred for 30 minutes at a rotation speed of 300 rpm. While maintaining this state, the heater was turned on and the mixture was heated, and the system temperature was maintained at 120°C while stirring for 60 minutes. After that, the mixture was cooled to room temperature (approximately 25°C) while being stirred in a water bath, and 64.5g of distilled water was added. The obtained dispersion was placed in a 1L round-bottom flask, and 176g of aqueous medium was removed by distillation under reduced pressure using an evaporator while the flask was placed in a water bath heated to 60°C. After cooling, the liquid components in the flask were pressure filtered (air pressure 0.2 MPa) using a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave). This yielded a milky white, uniform aqueous dispersion of acid-modified polyolefin resin E-1.

[0144] Synthesis Example 2: Synthesis of acid-modified polyolefin resin E-2 and aqueous dispersion of acid-modified polyolefin resin E-2 280 g of an ethylene copolymer (ethylene / ethyl acrylate / maleic anhydride = 91 / 7 / 2 (mass ratio)) was placed in a four-necked flask and heated to melt under a nitrogen atmosphere. Then, while maintaining the system temperature at 170°C and stirring, 6.0 g of di-t-butyl peroxide was added over 1 hour as a radical generator, and the reaction was continued for another hour. After the reaction was complete, the resulting reaction product was placed in a large amount of acetone to precipitate the resin. This resin was further washed several times with acetone to remove unreacted maleic anhydride, and then dried under reduced pressure in a vacuum dryer to obtain acid-modified polyolefin resin E-2.

[0145] An aqueous dispersion of acid-modified polyolefin resin E-2 was obtained in the same manner as in Synthesis Example 1, except that acid-modified polyolefin resin E-2 was used instead of acid-modified polyolefin resin E-1.

[0146] Synthesis Example 3: Synthesis of Acid-Modified Polyolefin Resin E-3 280 g of propylene-ethylene copolymer (propylene / ethylene = 99 / 1 (mass ratio)) was placed in a four-necked flask and heated to melt under a nitrogen atmosphere. While maintaining the system temperature at 170°C and stirring, 35.0 g of maleic anhydride as an unsaturated carboxylic acid and 6.0 g of di-t-butyl peroxide as a radical generator were added over 2 hours, followed by a reaction for 1 hour. After the reaction was complete, the resulting reaction product was placed in a large amount of acetone to precipitate the resin. This resin was further washed several times with acetone to remove unreacted maleic anhydride, and then dried under reduced pressure in a vacuum dryer to obtain acid-modified polyolefin resin E-3.

[0147] An aqueous dispersion of acid-modified polyolefin resin E-3 was obtained in the same manner as in Synthesis Example 1, except that acid-modified polyolefin resin E-3 was used instead of acid-modified polyolefin resin E-1.

[0148] Synthesis Example 4: Synthesis of Acid-Modified Polyolefin Resin Aqueous Dispersion E-4 280 g of propylene-butene-ethylene ternary copolymer (propylene / butene / ethylene = 68.0 / 16.0 / 16.0 (mass ratio)) was placed in a four-necked flask and heated to melt under a nitrogen atmosphere. Then, while maintaining the system temperature at 170°C and stirring, 32.0 g of maleic anhydride as an unsaturated carboxylic acid and 6.0 g of di-t-butyl peroxide as a radical generator were added over 1 hour each, and the reaction was continued for another hour. After the reaction was complete, the resulting reaction product was placed in a large amount of acetone to precipitate the resin. This resin was further washed several times with acetone to remove unreacted maleic anhydride, and then dried under reduced pressure in a vacuum dryer to obtain acid-modified polyolefin resin E-4.

[0149] An aqueous dispersion of acid-modified polyolefin resin E-4 was obtained in the same manner as in Synthesis Example 1, except that acid-modified polyolefin resin E-4 was used instead of acid-modified polyolefin resin E-1.

[0150] <Crosslinking agent> • WS-700: Oxazoline group-containing compound, manufactured by Nippon Shokubai Co., Ltd., "Epocross WS-700", solid content concentration 25% by mass • V-02-L2: Carbodiimide group-containing compound, "Carbodilite V-02-L2" manufactured by Nisshinbo Chemical Co., Ltd., solid content concentration 40% by mass

[0151] <Polyvinyl alcohol> Polyvinyl alcohol was prepared by dissolving the following in water to a solid content concentration of 8.0% by mass. • JM-17L: "JM-17L" manufactured by Nippon Vivipar Vinegar Co., Ltd., saponification degree 95.0%, average degree of polymerization 1700 • JF-10: "JF-10" manufactured by Nippon Vivaceus Vinegar Co., Ltd., saponification degree 98.5%, average degree of polymerization 1000 • JM-23: "JM-23" manufactured by Nippon Vivipar Vinegar Co., Ltd., saponification degree 95.0%, average degree of polymerization 2300 • JT-05: "JT-05" manufactured by Nippon Vivaceus Vinegar Co., Ltd., saponification degree 94.5%, average degree of polymerization 500 • VC-10: VC-10 manufactured by Nippon Vivaceuil Co., Ltd., saponification degree 99.4%, average degree of polymerization 1000

[0152] <Wetting agent> • Polyflow KL-900: Amphiphilic oligomer, manufactured by Kyoeisha Chemical Co., Ltd. • Olphine E1004: Ethylene oxide adduct of acetylene glycol, manufactured by Nisshin Chemical Industry Co., Ltd.

[0153] Preparation Example 1: Preparation of resin layer forming composition A-1 Composition A-1 for forming a resin layer was obtained by mixing an aqueous dispersion of acid-modified polyolefin resin E-1 with WS-700 as a crosslinking agent, an aqueous solution of JM-17L as polyvinyl alcohol, and Polyflow KL-900 as a wetting agent. Furthermore, 100 parts by mass of acid-modified polyolefin resin E-1 were mixed with 15 parts by mass of crosslinking agent solids and 100 parts by mass of polyvinyl alcohol solids. The amount of wetting agent mixed was 0.2% by mass of the total composition.

[0154] Preparation Examples 2-21: Preparation of resin layer forming compositions A-2-A-21 Resin layer-forming compositions A-2 to A-21 were obtained in the same manner as in Preparation Example 1, except that the formulation was modified as shown in Table 1 below.

[0155] [Table 1]

[0156] <Polyethylene terephthalate> The polyethylene terephthalate B-1 and B-2 constituting the support film were obtained from the synthesis examples described below.

[0157] Synthesis Example 5: Synthesis of Polyethylene Terephthalate B-1 Using antimony oxide as a catalyst, terephthalic acid and ethylene glycol were melt-polymerized by a conventional method to obtain polyethylene terephthalate B-1 (intrinsic viscosity: 0.62, glass transition temperature: 78°C, melting point: 255°C) that is substantially particle-free.

[0158] Synthesis Example 6: Synthesis of Polyethylene Terephthalate B-2 Polyethylene terephthalate B-2 (silica particle content: 0.07 mass%) was obtained in the same manner as in Synthesis Example 5, except that silica particles with an average particle size of 2.3 μm were added during melt polymerization.

[0159] Example 1 Polyethylene terephthalate B-1 and polyethylene terephthalate B-2 were fed into extruder I (screw diameter: 50 mm) and melted at 280°C to obtain a molten material. Polyethylene terephthalate B-1 was also fed into extruder II (screw diameter: 65 mm) and melted at 280°C to obtain another molten material. These molten materials were then merged and laminated in layers before reaching the exit of the T-die, with a layer thickness ratio (I / II) of 4 / 6 and a total thickness of 600 μm. The resulting material was extruded from the T-die exit and rapidly cooled and solidified to obtain an unstretched polyester film. The obtained unstretched polyester film was stretched 3.2 times in the MD direction at 85°C using a roll-type longitudinal stretcher to obtain a uniaxially oriented film in the MD direction. Next, resin layer forming composition A-1 was applied at a rate of 5 g / m² on the polyester film surface on the extruder II side (polyethylene terephthalate B-1 side) of the longitudinally oriented film using a 120-mesh gravure roll. 2 It was applied in this manner. Subsequently, the ends of the uniaxially stretched film in the MD direction were continuously gripped by clips on a flat stretcher, and stretched 4.3 times in the TD direction under conditions of 100°C. After that, a relaxation treatment was performed by heating at 230°C for 3 seconds with a relaxation rate of 0.3% in the TD direction. This resulted in a support film with a total thickness of 38 μm, in which a resin layer with a thickness of 0.1 μm was provided on one side of a two-layer polyester film of two types.

[0160] Examples 2-20, Comparative Examples 1-5 In Example 1, the same procedure as in Example 1 was followed, except that the manufacturing conditions for the support film were changed as shown in Table 2 below, to obtain a support film.

[0161] The process films obtained in the examples and comparative examples were evaluated in various ways, and the results are shown in Tables 3 and 4 below.

[0162] [Table 2]

[0163] [Table 3]

[0164] [Table 4]

[0165] The support films obtained in Examples 1 to 20 have a flat resin layer surface, excellent solvent resistance, good release properties from the cast film, and moderate adhesion. Furthermore, the resin layer is free of coating defects, has a small dimensional change rate in the TD direction, and the ratio of the dimensional change rates of MD to TD (MD dimensional change rate / TD dimensional change rate) is within a specific range. Therefore, these support films can be suitably used as support materials in the process of manufacturing resin films by the solution casting method.

[0166] The support film obtained in Comparative Example 1 had poor solvent resistance and poor surface flatness of the resin layer after solvent application because the average degree of polymerization of the polyvinyl alcohol contained in the resin layer did not meet the range specified in the present invention. Furthermore, the heat resistance of the resin layer was also insufficient.

[0167] In Comparative Example 2, the support film obtained had a degree of saponification of polyvinyl alcohol contained in the resin layer that exceeded the range specified in the present invention. As a result, the surface tension of the resin layer forming solution increased, the coating was unstable, and coating defects occurred on the surface of the resin layer.

[0168] The support film obtained in Comparative Example 3 had a large degree of relaxation in the TD direction during film formation, resulting in a ratio of the dimensional change rates in the MD direction to the TD direction (MD dimensional change rate / TD dimensional change rate) exceeding the range defined in this invention. Using such a support film as a support in the process of manufacturing a resin film by the solution casting method is undesirable because it causes wrinkles in the cast film.

[0169] The support film obtained in Comparative Example 4 had a high polyvinyl alcohol content in the resin layer, which resulted in an excessively low coefficient of dynamic friction between the cast film and the resin layer, thus reducing adhesion. When used as a support in the process of manufacturing resin films by the solution casting method, the cast film tends to slip during the process, making it undesirable.

[0170] The support film obtained in Comparative Example 5 had a low polyvinyl alcohol content in the resin layer, which prevented the removal of the cast film.

[0171] In summary, the configuration of the present invention and its variations are described below. [1] A configuration having a resin layer provided on at least one surface of a polyester film, The resin layer contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more. The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. A film in which the dimensional change rate in the TD direction is 2.0% or less after heat treatment at 160°C for 15 minutes, and the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) is 0.5 to 1.5. [2] The film according to [1], wherein the arithmetic mean roughness Sa of the resin layer surface is 20 nm or less. [3] Xylene 0.5 g / m 2 The film described in [1] or [2], which is coated in such a manner, heated at 160°C for 20 seconds to dry, and then measures with an acrylic adhesive tape (manufactured by Nitto Denko Corporation, No. 31B) to obtain a residual adhesion rate of 70% or more. [4] A film according to any one of [1] to [3], wherein the arithmetic mean roughness Sa(1) of the resin layer surface after dropping xylene onto it, holding it in a 25°C environment for 30 minutes, and drying it at 160°C for 5 minutes, and the arithmetic mean roughness Sa(2) of the resin layer surface before dropping xylene onto it, satisfy the following formula (a). [{Sa(1)-Sa(2)} / Sa(2)]×100≦20 (a) [5] The film according to any one of [1] to [4], wherein the crosslinking agent content is 1 to 40 parts by mass per 100 parts by mass of acid-modified polyolefin resin. [6] A film according to any one of [1] to [5], wherein the crosslinking agent is an oxazoline group-containing compound. [7] A film used as a support in the process of manufacturing a resin film by the solution casting method, as described in any one of [1] to [6]. Use of any one of the films described in [8], [1], to [6] as a support in the process of manufacturing a resin film by the solution casting method. A laminate in which a cast film is laminated on the resin layer surface of a fill described in any one of [9][1] to [6]. A method for manufacturing fill as described in any one of

[10] [1] to [6], Step 1 involves applying the following resin layer-forming composition to at least one surface of a polyester film and drying it to form a laminate of the coating and the polyester film. Step 2 of stretching the laminate, Step 3 involves subjecting the stretched laminate to a relaxation treatment of 0.1-2.0%, A method for manufacturing a film having the following characteristics. Composition for forming a resin layer: Contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a degree of saponification of 99.0% or less and an average degree of polymerization of 1000 or more, wherein the content of the polyvinyl alcohol is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. [Industrial applicability]

[0172] The support film of the present invention exhibits excellent surface flatness, solvent resistance, and dimensional stability of the resin layer surface. Therefore, it can be suitably used as a support in the process of manufacturing resin films by the solution casting method. Furthermore, when a cast film is formed using the support film of the present invention as a support, the resin layer can hold the formed cast film with appropriate adhesion, and the cast film can be easily peeled off the resin layer.

Claims

1. A film used as a support in the process of manufacturing a resin film by the solution casting method, The structure has a resin layer provided on at least one surface of the polyester film. The resin layer contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more. The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. The arithmetic mean roughness Sa of the surface of the resin layer is 20 nm or less. A film in which the dimensional change rate in the TD direction is 2.0% or less after heat treatment at 160°C for 15 minutes, and the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) is 0.5 to 1.

5.

2. A film used as a support in the process of manufacturing a resin film by the solution casting method, The structure has a resin layer provided on at least one surface of the polyester film. The resin layer contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more. The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. The dimensional change rate in the TD direction after heat treatment at 160°C for 15 minutes is 2.0% or less, and the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) is 0.5 to 1.

5. A film coated with xylene at a concentration of 0.5 g / m², dried by heating at 160°C for 20 seconds, and then measuring the residual adhesion rate using acrylic adhesive tape (manufactured by Nitto Denko Corporation, No. 31B) to a level of 70% or higher.

3. A film used as a support in the process of manufacturing a resin film by the solution casting method, The structure has a resin layer provided on at least one surface of the polyester film. The resin layer contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a saponification degree of 99.0% or less and an average degree of polymerization of 1000 or more. The polyvinyl alcohol content is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. The dimensional change rate in the TD direction after heat treatment at 160°C for 15 minutes is 2.0% or less, and the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (MD dimensional change rate / TD dimensional change rate) is 0.5 to 1.

5. A film in which the arithmetic mean roughness Sa(1) of the resin layer surface after dropping xylene onto it, holding it in a 25°C environment for 30 minutes, and drying it at 160°C for 5 minutes, and the arithmetic mean roughness Sa(2) of the resin layer surface before dropping xylene onto it, satisfy the following formula (a). [{Sa(1)-Sa(2)} / Sa(2)]×100≦20 (a)

4. The film according to any one of claims 1 to 3, wherein the crosslinking agent content is 1 to 40 parts by mass per 100 parts by mass of the acid-modified polyolefin resin.

5. The film according to any one of claims 1 to 3, wherein the crosslinking agent is an oxazoline group-containing compound.

6. A laminate comprising a cast film laminated on the resin layer surface of a film according to any one of claims 1 to 3.

7. A method for manufacturing a film according to any one of claims 1 to 3, Step 1 involves applying the following resin layer-forming composition to at least one surface of a polyester film and drying it to form a laminate of the coating and the polyester film. Step 2 of stretching the laminate, Step 3 involves subjecting the stretched laminate to a relaxation treatment of 0.1 to 2.0%, A method for manufacturing a film having the following characteristics. Composition for forming a resin layer: Contains an acid-modified polyolefin resin, a crosslinking agent, and polyvinyl alcohol with a degree of saponification of 99.0% or less and an average degree of polymerization of 1000 or more, wherein the content of the polyvinyl alcohol is 5 to 500 parts by mass per 100 parts by mass of the acid-modified polyolefin resin.

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