JP6653485B2 - Release film - Google Patents

Description

  The present invention relates to a release film based on a polyester film. More specifically, the present invention relates to a release film for a high-temperature heating step, which can significantly reduce contamination by oligomers by reducing the amount of oligomers precipitated from a polyester film during high-temperature heating.

  In recent years, the use of various film materials in the field of optical display such as liquid crystal and organic EL has been dramatically increased with the growth of information technology related business.

  A release film based on a polyester film is also one of those materials. In order to manufacture an adhesive sheet (OCA: Optically Clear Adhesive) used for bonding optical films, a release film is used. It is widely used as a structure of release film / OCA / release film.

  As an application of the OCA, there is an application for bonding a transparent conductive film of indium tin oxide laminated film (ITO film) to an adherend such as glass. That is, in this application, one of the release films of the release film / OCA / release film is peeled off and adhered to the ITO film to form an ITO film / OCA / release film. After being cut in this laminated structure, the cut is fired at a high temperature of 140 to 160 ° C. for a long time to increase the crystallinity of ITO. At this time, the oligomer precipitated from the polyester film of the release film may adhere to the OCA or mix into the OCA. Thereafter, the release film is peeled off and adhered to the adherend, which causes problems such as a decrease in the transparency of OCA due to oligomers and the generation of bright spots.

  In order to suppress oligomers precipitated from the polyester film surface, the content of the ethylene terephthalate cyclic trimer is reduced to less than 0.4% by weight based on polyester (Patent Document 1). This polyester film has improved oligomer precipitation prevention performance, but its prevention performance was insufficient. A release film is provided by providing a release layer, and in the above-described ITO manufacturing process, it is baked at a high temperature for a long time in the configuration of ITO film / OCA / release film in order to increase the crystallinity of ITO. Then, the oligomer precipitated from the polyester film used for the release film adheres to and mixes with the OCA, so that when the ITO film with the OCA is laminated, a luminescent spot, surface roughness, and transparency that cause defects are generated. However, the problem of the decrease in the temperature cannot be solved.

  In addition, there is a disclosure of a release film capable of suppressing precipitation of oligomers by providing a release layer having a specific resin composition on a polyester film (Patent Document 2). There is also a disclosure in which a specific coating layer is provided on at least one surface of a polyester film to prevent oligomer precipitation (Patent Documents 3 and 4). However, even when a release layer and a coat layer of these specific resin compositions are provided, oligomers are generated to the same degree as those without a coat layer when heated at a high temperature for a long time, and the effect is limited. It was a target.

JP 2003-119271 A JP-A-2004-82370 JP 2005-89622 A JP 2014-046503 A

  An object of the present invention is to provide a release film capable of highly suppressing the precipitation of oligomers on the surface of a release layer even after a long-time heat treatment at a high temperature.

  In order to solve the above problems, the present invention has the following configurations.

In the first invention, a primer layer and a release layer are formed on a coat layer surface of a polyester film in which a coat layer made of at least one resin selected from polyester resin, acrylic resin or urethane resin is laminated on at least one surface. A release film laminated in sequence, wherein the number of oligomers having a size of 5 μm or more on the surface of the coating layer after heating the release film at 180 ° C. for 180 minutes is 400 or less / mm ² , and a thickness of 5 μm on the surface of the release layer. A release film characterized in that the number of the oligomers is 50 or less / mm ² .

  A second invention is characterized in that the primer layer comprises an organosilicon compound and an organometallic compound.

  A third invention is characterized in that the thickness of the primer layer is in the range of 20 nm to 300 nm.

  A fourth invention is characterized in that the release layer is a silicone resin.

  The release film of the present invention has an oligomer precipitation preventing property that could not be achieved by the prior art, and even when used as a release film of OCA at a high temperature, the amount of oligomer precipitation is suppressed to cause a defect in OCA. Luminescent spots, surface roughness, and decrease in transparency can be prevented.

In the present invention, a primer layer and a release layer are laminated in this order on a coat layer surface of a polyester film in which a coat layer made of at least one resin selected from a polyester resin, an acrylic resin or a urethane resin is laminated on at least one surface. A release film, wherein the number of oligomers of 5 μm or more on the surface of the coating layer after heating the release film at 180 ° C. for 180 minutes is 400 or less / mm ² , and the amount of oligomers of 5 μm or more on the surface of the release layer. Is 50 or less / mm ² .

  The polyester constituting the polyester film in the present invention is preferably a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, and examples thereof include a homopolyester and a copolymerized polyester. As the homopolyester, those obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol are preferable. 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. Representative polyesters include polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like. Examples of the dicarboxylic acid component of the copolymerized polyester include phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acids such as paraoxybenzoic acid. A combination of two or more species is exemplified, and examples of the glycol component include a combination of one or two kinds of ethylene glycol, diethylene glycol, neopentyl glycol and the like.

  The coat layer in the present invention is made of at least one resin selected from a polyester resin, an acrylic resin, and a urethane resin, and may be provided on one side or both sides of the polyester film.

  The polyester resin in the coat layer of the present invention has an ester bond in a main chain or a side chain, and such a polyester resin can be obtained by polycondensation from an acid component and a glycol component. When a polyester resin is used as an aqueous coating liquid, it is preferable to copolymerize a compound containing a sulfonic acid group or a compound containing a carboxylic acid group in terms of adhesion and water solubility. The glass transition temperature of the polyester resin is preferably from 0 to 120C. Further, as the polyester resin, a modified polyester copolymer, for example, a block copolymer or a graft copolymer modified with acryl, urethane, epoxy or the like can be used.

  The acrylic resin in the coating layer of the present invention can be particularly preferably used in a proportion of at least 20 parts by weight of the resin in the coating layer in terms of adhesiveness and oligomer suppressing property among the resins in the coating layer. As a monomer component constituting the acrylic resin, for example, an alkyl acrylate, an alkyl methacrylate, or the like can be used, and these are copolymerized using one kind or two or more kinds. Further, they can be used in combination with other types of monomers. As other types of monomers, for example, a monomer containing a sulfonic acid group or a salt thereof, a monomer containing an acid anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl tris alkoxysilane, alkyl Maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride and the like can be used. The glass transition temperature of the acrylic resin is preferably from 0 to 70C. Further, as the acrylic resin, a modified acrylic copolymer, for example, a block copolymer or a graft copolymer modified with polyester, urethane, epoxy or the like can be used.

  The urethane resin in the coat layer of the present invention is not particularly limited as long as it has a urethane bond in a molecular structure, and a reaction product obtained from a polyol compound and an isocyanate compound has a basic skeleton thereof. is there.

  Further, other resins, for example, an epoxy resin, a silicone resin, a urea resin, a phenol resin and the like may be blended in the coat layer in the present invention as long as the effects of the present invention are not impaired.

  When applying at least one resin selected from a polyester resin, an acrylic resin, and a urethane resin in the coat layer of the present invention as an aqueous coating solution, it is necessary to dissolve or disperse in water, and to use an emulsifier. For example, a surfactant (for example, a polyether-based compound may be mentioned, but not limited thereto) may be used. If the used amount of the emulsifier is too large, the adhesiveness and the oligomer-suppressing property may be impaired, and if the used amount of the emulsifier is too small, the stability as an aqueous coating liquid may be impaired.

  Further, the coating layer in the present invention, within a range that does not impair the effect of the present invention, various additives, for example, antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, lubricants, pigments, dyes , Organic or inorganic fine particles, fillers, antistatic agents, nucleating agents, and the like. In particular, it is optional to add particles, a cross-linking agent, and a surfactant (for example, but not limited to, a polyether-based compound and a fluorine-based compound) to the oligomer precipitation-preventing layer in the present invention. It is preferable because lubricity, blocking resistance, adhesion, appearance after coating, and oligomer suppression are improved.

  In the present invention, it is preferable to use a laminated polyester film having a coat layer in which a polyester film has been coated in-line in advance. The coat layer may have other functions as long as it has a function of preventing oligomer precipitation from polyester, and may have ultraviolet absorption, easy adhesion, hard coat properties, antireflection properties, antiglare properties, It may have a function such as antistatic property.

The oligomer-preventing property of the coat layer according to the present invention requires that the number of precipitated oligomers of 5 μm or more after the heat treatment at 180 ° C. for 180 minutes be 400 or less / mm ² . When the number is 400 or more / mm ² , as a release film, the deposited oligomer leads to a decrease in conductivity, a luminescent spot or surface roughness which causes defects, a decrease in transparency, and a process contamination.

Next, the primer layer in the present invention will be described. The primer layer in the present invention suppresses the oligomer precipitated from the polyester film from adhering to the OCA or mixing into the OCA even if the release film is treated for a long time at a high temperature, and has a bright spot, a rough surface, and transparency. Can be prevented from lowering and poor appearance. The composition preferably contains an organic silicon compound, and it is preferable to use an organic silicon compound represented by the following general formula (1).
Si (X) a (Y) b (R1) c (1)
(X: an alkylene group to which one selected from a glycidoxy group, a mercapto group, a (meth) acryloxy group, and an amino group is bonded, or an alkenyl group, a haloalkyl group, R1: a monovalent hydrocarbon group, Is 1 to 12, Y is a hydrolyzable group, a is 0 or 1, b is 2 or 3, c is an integer of 0 to 2, and a + b + c = 4.)
The organosilicon compound represented by the general formula (1) is a compound having two hydrolyzable groups Y capable of forming a siloxane bond by hydrolysis / condensation reaction (D unit source) or a compound having three hydrolyzable groups Y (T unit). Source) can be used.

  In the general formula (1), the monovalent hydrocarbon group R1 has 1 to 12 carbon atoms, and particularly includes a methyl group, an ethyl group, and a propyl group.

  In the general formula (1), examples of the hydrolyzable group Y include a methoxy group, an ethoxy group, a butoxy group, an isopropenoxy group, an acetoxy group, a butanoxime group, a ketoxime group and an amino group. These hydrolyzable groups may be used alone or in combination. The use of a methoxy group or an ethoxy group is particularly preferred because the primer layer can be formed well and has good hydrolyzability.

  As the organic silicon compound in the present invention, specifically, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyl Triethoxysilane, cyclohexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-mercaptopropyltrimethoxy Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiet Sisilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- ( (Aminoethyl) -3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 5-hexenyltrimethoxysilane Trifluoropropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 −Guri De carboxypropyl methyl di isopropenoxysilane silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like can be exemplified.

  In order to improve the catalytic role of the primer layer in the hydrolysis of the organosilicon compound in the present invention, and to improve the coating adhesion between the release layer and the polyester film, at least one or two kinds of organometallic compounds containing a metal element are used. As described above, it is preferable to contain it in the primer layer. Among them, an organometallic compound containing a metal element selected from aluminum, zirconium, and titanium is preferable, and an organometallic compound having a chelate structure is particularly preferable, since the organometallic compound has particularly good oligomer deposition preventing performance.

  Specific examples of the organometallic compound having an aluminum element include bis (ethylacetoacetate) (2,4-pentanedionate) aluminum, aluminum tris (acetylacetonate), and aluminum monoacetylacetonate bis (ethylacetoacetate). , Aluminum-di-n-butoxide-monoethylacetoacetate, aluminum-di-iso-propoxide-monomethylacetoacetate, aluminum tris (ethylacetoacetate) and the like.

  Specific examples of the organometallic compound having a titanium element include, for example, titanium orthoesters such as tetranormal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate and tetramethyl titanate, and titanium acetylacetonate And titanium chelates such as titanium tetraacetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolaminate, and titanium ethyl acetoacetate.

  Specific examples of the organometallic compound having a zirconium element include, for example, zirconium acetate, zirconium normal propylate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate and the like.

  The amount of the organometallic compound contained in these primer layers is 0.001 to 70% by weight, preferably 5 to 30% by weight, and more preferably 5 to 15% by weight. When the amount of the organometallic compound is 0.001% by weight or less, the curing reaction of the coating layer does not proceed rapidly, and the coating adhesion of the release surface after forming the release layer on the coating layer is deteriorated. May be. When the amount of the organometallic compound is 70% by weight or more, the organometallic compound remaining in the coating layer does not participate in the curing reaction of the coating layer and prevents the curing of the release layer. The film adhesion may be deteriorated.

  Although the primer layer may contain inert fine particles, specific examples of such inert fine particles include, for example, wet and dry silica, colloidal silica, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, barium carbonate, and zinc carbonate. , Calcium silicate, aluminum hydroxide, magnesium hydroxide, calcium sulfate, barium sulfate, calcium phosphate, magnesium phosphate, clay, kaolin, mica, talc, zeolite, diatomaceous earth, crystalline silica, aluminum oxide, titanium oxide, zinc oxide, Examples include inorganic fine particles such as carbon black. The shape of the inorganic fine particles to be used is not limited, and examples thereof include a spherical shape, a massive shape, a rod shape, a flat shape, and a scale shape.

  The particle content in the primer layer is 0.001 to 5% by weight, preferably 0.005 to 3% by weight.

  The thickness of the primer layer is preferably from 20 to 300 nm, more preferably from 50 to 250 nm. If the primer layer is less than 20 nm, the oligomer suppression performance may be insufficient. If the primer layer is too thick, the flatness and the drying property are deteriorated. In addition, the primer layer is a three-dimensionally cross-linked resin layer. Since it is brittle, it may be a starting point of falling off or surface defects when applying a release layer.

  In order to form these primer layers, as a method of applying to a polyester film, a general coating method can be used. For example, a coating method such as a gravure coat, a gravure reverse coat, a lip coat, a die coat, a microgravure coat, a Meyer bar coat, and a multi-stage reverse coat can be used.

  In the primer layer in the present invention, various additives, for example, an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a lubricant, a pigment, a dye, and a charge are added as long as the effects of the present invention are not impaired. An inhibitor, a nucleating agent, and the like may be blended. It is optional to add particles, a crosslinking agent, and a surfactant (for example, but not limited to, a polyether-based compound and a fluorine-based compound) to the primer layer. It is preferable because the adhesiveness, the appearance after application, and the oligomer inhibiting property are improved.

  Known materials can be appropriately used as the release layer forming material in the present invention. For example, alkyd resin-based release agent, polyolefin-based release agent, long-chain alkyl group-containing resin-based release agent, fluorine-based release agent, silicone-based release agent, mixed or copolymerized resin of organic and silicone-based Release agents and the like. Among these, silicone-based release agents are particularly preferred because of their excellent release properties and heat resistance. Silicone release agents can be classified by reaction type into heat-curable types such as addition-reaction type and condensation-reaction type, ultraviolet ray-curable type, electron beam-curable type, and combined use type of heat and ultraviolet ray. A release agent may also be used.

  The thickness of the release layer is preferably from 10 to 500 nm, more preferably from 30 to 200 nm. If the coating layer is too thin, the peeling performance is reduced, and if the coating layer is too thick, flatness, drying properties, and uneven coating of the appearance occur, and in addition, silicone transferability is not preferable.

  As a method of applying these release layer forming agents to a polyester film, a general coating method can be used. For example, a coating method such as a gravure coat, a gravure reverse coat, a lip coat, a die coat, a microgravure coat, a Meyer bar coat, and a multi-stage reverse coat can be used.

In the present invention, the curing conditions for forming the primer layer and the release layer on the polyester film are not particularly limited, and the curing conditions are 60 to 200 ° C. for 3 to 40 seconds, preferably 80 to 180 ° C. for 3 to 40 seconds. Heat treatment is preferably performed for up to 40 seconds. If necessary, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination.
Further, the polyester film constituting the release film may be subjected to a surface treatment such as a corona treatment or a plasma treatment in advance.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

  The measuring method used in the present invention is as follows.

<Oligomer precipitation amount (number confirmation)>
(1) The film is hung on a stand and heated in an oven at 180 ° C. for 180 minutes.
(2) After removing from the oven and cooling to room temperature, the opposite side of the side for confirming the amount of precipitated oligomer is carefully wiped off with a cotton cloth impregnated with toluene.
(3) After air-drying, the measurement surface was observed with an optical microscope (× 400), and the number of oligomers having a maximum length of precipitated oligomers of 5 μm or more was counted. (Target area: 0.056 mm ² ) n = 15 was confirmed by the above method, and the total number of these oligomers was converted per 1 mm ² to obtain the oligomer precipitation amount (number) of the sample.

(Example 1)
"XIAMETER" OFS-6030SILANE which is 3-glycidoxypropyltrimethoxysilane BY24-846B (manufactured by Dow Corning Toray Co., Ltd., content 98% by weight) and 3-methacryloxypropyltrimethoxysilane 1 part by weight (manufactured by Toray Dow Corning Co., Ltd., content: 99% by weight), BY24-846E which is bis (ethylacetoacetate) (2,4-pentanedionate) aluminum (manufactured by Toray Dow Corning Co., Ltd.) , A content of 38% by weight) were mixed with 50 parts by weight of toluene and 50 parts by weight of IPA to prepare a primer coating liquid.

  Addition-reaction type curable silicone resin KS847H (Shin-Etsu Chemical Co., Ltd.) 4 parts by weight, PL-50T (Shin-Etsu Chemical Co., Ltd.) 0.04 parts by weight and toluene 50 parts by weight And a release layer coating liquid mixed with 50 parts by weight of n-heptane.

  A primer coating solution was applied on the coated surface of a 125 μm-thick polyethylene terephthalate film (“Lumirror” (registered trademark) XD1NB1 manufactured by Toray Industries, Inc.) in which an acrylic resin-based coating layer was provided on one side during film formation. The Meyer bar No. was adjusted so that the coating thickness after drying was 50 nm. 3 and dried and cured at 100 ° C. for 5 seconds. Then, a release layer coating liquid is continuously applied to the coating layer of Meyer Bar No. 5 so that the coating thickness becomes 50 nm. 5 and dried and cured at 150 ° C. for 20 seconds to obtain a release film. The amount of oligomer precipitated on the surface of the coating layer and the surface of the release layer of "Lumirror" XD1NB1 was measured. The results are shown in Table 1. An oligomer-preventing property was imparted, and the releasability was good.

(Example 2)
The primer coating solution of Example 1 was applied to a Meyer bar No. 1 such that the coating thickness after drying was 200 nm. A release film was obtained in the same manner except that the coating was performed in Step No. 10. An oligomer-preventing property was imparted, and the releasability was good.

(Example 3)
The primer coating solution of Example 1 was further diluted with 50 parts by weight of toluene and 50 parts by weight of IPA, and the Mayer bar No. 1 was dried so that the coating thickness after drying was 25 nm. A release film was obtained in the same manner except that the coating was performed in Step 3. An oligomer-preventing property was imparted, and the releasability was good.

(Comparative Example 1)
In Example 1, a release film was obtained in which only the release layer coating liquid was applied without applying the primer coating liquid. Many oligomers precipitated on the film surface.

(Comparative Example 2)
The primer coating liquid of Example 1 was further diluted with 110 parts by weight of toluene and 110 parts by weight of IPA to prepare a primer coating liquid, and the primer coating liquid was dried so that the coating thickness after drying was 17 nm. No. A release film was obtained in the same manner except that the coating was performed in Step 3. Many oligomers precipitated on the film surface.

(Comparative Example 3)
In the same manner as in Example 1, except that an acrylic resin-based coating layer was applied on the non-coated surface of a 125 μm-thick polyethylene terephthalate film (“Lumirror” XD1NB1 manufactured by Toray Industries, Inc.) provided on one surface. A release film was obtained. The oligomer precipitation amount on the uncoated surface and the release layer surface of the polyethylene terephthalate film was measured. It was confirmed that oligomers were precipitated on the surface of the release layer.

(Comparative Example 4)
Applying only a release layer coating solution directly to the non-coated surface of a 125 μm-thick polyethylene terephthalate film (“Lumirror” XD1NB1 manufactured by Toray Industries, Inc.) having an acrylic resin-based coating layer provided on one surface, I got It was confirmed that oligomers were precipitated on the surface of the release layer.

(Comparative Example 5)
A release film was prepared in the same manner as in Example 2, except that a 125 μm-thick polyethylene terephthalate film (“Lumirror” U463 manufactured by Toray Industries, Inc.) provided with a polyester resin-based coat layer on one side was used. . The amount of oligomer precipitated on the surface of the coating layer and the surface of the release layer of "Lumirror" U463 was measured. The amount of oligomer on the surface of the release layer could not be reduced to 50 / mm ² or less.

Claims (4)

A mold release in which a primer layer and a release layer are laminated in this order on a coat layer surface of a polyester film in which a coat layer made of at least one resin selected from a polyester resin, an acrylic resin or a urethane resin is laminated on at least one surface. A film, wherein the polyester film on which the coating layer is laminated is subjected to heat treatment at 180 ° C. for 180 minutes , and the number of oligomers of 5 μm or more on the coating layer surface is 400 or less / mm ² , and the release film is release film 5μm or more oligomers in the release layer surface after 180 minutes heat treatment at 180 ° C. is characterized in that it is a 50 or less / mm ^2.   The release film according to claim 1, wherein the primer layer comprises an organosilicon compound and an organometallic compound.   The release film according to claim 1, wherein the thickness of the primer layer is in a range of 20 nm to 300 nm. The release film according to any one of claims 1 to 3, wherein the release layer comprises a silicone resin.