JP5952049B2 - Adhesive film - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive film that has antistatic properties and does not deteriorate in appearance even after being exposed to a high temperature, for example.

  Biaxially stretched polyester film is excellent in transparency, dimensional stability, mechanical properties, heat resistance, electrical properties, etc. Adhesive films based on this biaxially stretched polyester film are also used in many fields. .

  However, a pressure-sensitive adhesive film using a biaxially stretched polyester film as a base material has a characteristic that it is easy to be charged due to static electricity as a common problem with plastic films. For this reason, problems such as poor running performance of the processed film or processed product, and surrounding dust are caused.

  In order to suppress such charging, a mixture of an antistatic agent and an adhesive has been proposed (Patent Document 1). However, the pressure-sensitive adhesive mixed with the antistatic agent has a problem that the antistatic agent bleeds from the pressure-sensitive adhesive layer with time, and the performance deteriorates or the pressure-sensitive adhesive property changes.

  On the other hand, in recent years, as an application in which an adhesive film is used, those subjected to processing at a high temperature are increasing. For example, in a protective film that is increasingly used for a touch panel or the like and bonded to a transparent conductive laminate, there is a treatment such as heat treatment at 150 ° C. for crystallization of ITO (Patent Document 2). However, as a problem of the polyester film, when exposed to such high-temperature and long-time treatment, oligomers contained in the film (low molecular weight components of polyester, particularly cyclic trimers) are precipitated from the inside of the film. The oligomer thus precipitated crystallizes inside the pressure-sensitive adhesive layer and becomes a foreign substance, thereby causing a problem that the visual inspection is hindered.

  Therefore, the pressure-sensitive adhesive sheet using a biaxially stretched polyester film as a base material does not have sufficient characteristics to withstand use depending on applications, and improvement is required.

Japanese Patent Application Laid-Open No. 5-2799641 JP 2007-200823 A

  The present invention has been made in view of the above-mentioned circumstances, and the problem to be solved is that the problem due to charging is suppressed, for example, suppressing oligomers that precipitate from the film when exposed to high temperatures, and during film storage and film use. An object of the present invention is to provide an adhesive film that does not cause problems associated with oligomers during film processing.

  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by providing a specific undercoat layer between the polyester film substrate and the adhesive layer. It came to complete.

  That is, the gist of the present invention is to have a subbing layer obtained by applying a coating liquid containing a quaternary ammonium group-containing polymer and a polyvalent aldehyde compound to a substrate made of a biaxially stretched polyester film and drying it. And it exists in the adhesive film characterized by the adhesive layer being laminated | stacked on the said undercoat layer.

  According to the laminated polyester film of the present invention, since charging during film running is suppressed, it can be used without causing processing troubles such as attracting dust, and even when subjected to high temperature and long time processing, Since the oligomer precipitation is suppressed, it is possible to obtain a product having an excellent appearance without generation of foreign matter on the adhesive layer, and its industrial utility value is high.

The base film of the pressure-sensitive adhesive film of the present invention is made of polyester. Such polyesters include dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid or esters thereof. It is a polyester produced by melt polycondensation with glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol. Polyesters composed of these acid components and glycol components can be produced by arbitrarily using a commonly used method.
For example, a transesterification reaction between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or a direct esterification of an aromatic dicarboxylic acid and a glycol, to form a substantially bisglycol of an aromatic dicarboxylic acid A method is employed in which an ester or a low polymer thereof is formed and then polycondensed by heating under reduced pressure. Depending on the purpose, an aliphatic dicarboxylic acid may be copolymerized.

  Typical examples of the polyester of the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. It may be a polymerized polyester and may contain other components and additives as necessary.

  The polyester film in the present invention has a single layer or multilayer structure. In the case of a multilayer structure, the surface layer and the inner layer, or both the surface layer and each layer can be made of different polyesters depending on the purpose.

  Moreover, when adding an additive in a film, it can add to a single layer film, or it can add only to the one part layer of a multilayer film. For example, the film has a three-layer structure, and particles are not added to the inner layer, but particles are added to one or both outer layers, thereby making it possible to achieve both the slipperiness and the transparency.

  The polyester film in the present invention can contain particles for the purpose of ensuring the film runnability and preventing scratches. Examples of such particles include inorganic particles such as silica, calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Further, organic particles such as crosslinked polymer particles and calcium oxalate, and precipitated particles during the polyester production process can be used.

The particle size and content of the particles to be used are selected according to the use and purpose of the film, but the average particle size (d50) is usually 0.01 to 3 μm, preferably 0.02 to 2.5 μm, more preferably Is in the range of 0.03 μm to 2 μm. If the average particle size exceeds 3.0 μm, the surface roughness of the film becomes too rough, or the particles are likely to fall off from the film surface. When the average particle size is less than 0.01 μm, the surface roughness is too small and sufficient slipperiness may not be obtained.

  About particle content, it is 0.0003 to 1.0 weight% normally with respect to the polyester layer containing particle | grains, Preferably it is the range of 0.0005 to 0.5 weight%. When the particle content is less than 0.0003% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 1.0% by weight, the transparency of the film is poor. It may be enough. In addition, when it is particularly desired to ensure transparency, smoothness, etc. of the film, it can also be configured so as not to substantially contain particles. Further, various stabilizers, lubricants, antistatic agents and the like can be appropriately added to the film.

  The haze of the polyester film that is the base film of the present invention is preferably 10% or less. More preferably, it is 5% or less, More preferably, it is 3% or less. If it is larger than this range, it may be difficult to use in appearance in optical applications.

  As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, a sheet obtained by melt extrusion is first stretched 2 to 6 times at 70 to 145 ° C. by a roll stretching method to obtain a uniaxially stretched polyester film, and then perpendicular to the previous stretching direction in the tenter. A film is obtained by extending | stretching 2 to 6 times at 80-160 degreeC to the direction, and also heat-processing at 150-250 degreeC for 1 to 600 seconds. Further, at this time, a method of relaxing 0.1 to 20% in the longitudinal direction and / or the transverse direction in the heat treatment zone and / or the cooling zone at the heat treatment outlet is preferable.

  The undercoat layer of the present invention can be provided by either so-called off-line coating, in which a coating layer is provided later on the formed film, or so-called in-line coating, in which a coating layer is provided during film formation. However, it is preferably provided by in-line coating, particularly a coating stretching method in which stretching is performed after coating.

  In-line coating is a method of coating within the process of manufacturing a polyester film. Specifically, it is a method of coating at any stage from melt extrusion of polyester to biaxial stretching and then heat setting and winding. is there. Normally, it is coated on either a substantially amorphous unstretched sheet obtained by melting and quenching, then a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction), or a biaxially stretched film before heat setting. To do. In particular, as a coating stretching method, a method of stretching in the transverse direction after coating on a uniaxially stretched film is excellent.

  According to such a method, since film formation and coating layer coating can be performed at the same time, there is a merit in manufacturing cost. Stabilize. Moreover, the polyester film before biaxial stretching is first covered with a resin layer constituting the coating layer, and then the base film and the coating layer are firmly adhered by stretching the film and the coating layer simultaneously. become. In addition, the biaxial stretching of the polyester film is achieved by stretching the film in the lateral direction while holding the film end with a tenter clip, so that the film is constrained in the longitudinal / lateral direction and is flat without wrinkles or the like in heat setting. High temperature can be applied while maintaining the properties. Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the coating layer is improved, and the coating layer and the polyester film are firmly adhered. As the polyester film provided with the coating layer, the uniformity of the coating layer, the improvement of the film forming property, and the adhesion between the coating layer and the film often produce preferable characteristics. However, since heat resistance is required for the resin used as the coating layer, it is necessary to sufficiently study the selection of the resin to be used.

  In the case of the coating stretching method, the coating solution to be used is preferably an aqueous solution or an aqueous dispersion for safety reasons in terms of handling, working environment, but water is the main medium and does not exceed the gist of the present invention. If so, an organic solvent may be contained.

  The undercoat layer of the present invention is obtained by applying a coating solution containing a quaternary ammonium group-containing polymer and a polyvalent aldehyde compound and drying. The coating solution may contain other components.

  The quaternary ammonium group-containing polymer here refers to a polymer compound having a quaternized ammonium group in the molecule.

  In the present invention, for example, a polymer containing as a component a monomer having a quaternary ammonium group and an unsaturated double bond can be used.

  Specific examples of such a polymer include a polymer having a constituent represented by the following formula 1 or 2 as a repeating unit. These homopolymers and copolymers, and other plural components may be copolymerized.

In the above formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is —O— or —NH—, R ³ is an alkylene group having 1 to 6 carbon atoms or the structure of formula 1 Other possible structures, R ¹ , R ² and R ³ are each a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X ⁻ is a monovalent anion.

In the above formula, R ¹ and R ² are each a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X ⁻ is a monovalent anion.

A polymer having a component represented by Formula 1 is preferable because of excellent transparency of the resulting coating layer. However, in the coating stretching method, heat resistance may be inferior, and when used in the coating stretching method, X ⁻ is preferably not a halogen.

  The compound represented by Formula 2 and other compounds having a quaternary ammonium base in the polymer skeleton are excellent in heat resistance, and antistatic properties are easily obtained even in a coating stretching method.

  In addition, the polymer in which the component represented by the formulas 1 and 2 and the polyethylene glycol-containing (meth) acrylate are copolymerized has a flexible structure, and has a uniform coating layer during coating and stretching. Is preferable.

  Alternatively, a coating layer having excellent uniformity can also be obtained by coating a polyethylene glycol-containing (meth) acrylate polymer in a coating solution.

  Specific examples of the polyethylene glycol-containing (meth) acrylate include polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, polyethylene glycol diacrylate (the polymerization degree of polyethylene glycol units is preferably in the range of 4 to 14), and polypropylene glycol diacrylate. Acrylate, polytetramethylene glycol diacrylate, poly (ethylene glycol-tetramethylene glycol) diacrylate, poly (propylene glycol-tetramethylene glycol) diacrylate, polyethylene glycol-polypropylene glycol-polyethylene glycol diacrylate, polypropylene glycol-polybutylene glycol Monomethacrylate, methoxypolyethylene glycol Methacrylate, methoxy polyethylene glycol monoacrylate, octoxy polyethylene glycol-polypropylene glycol monomethacrylate, octoxy polyethylene glycol-polypropylene glycol monoacrylate, lauroxy polyethylene glycol monomethacrylate, lauroxy polyethylene glycol monoacrylate, stearoxy polyethylene glycol monomethacrylate, steer Examples include polymers starting from loxypolyethylene glycol monoacrylate, allyloxypolyethylene glycol monomethacrylate, allyloxypolyethylene glycol monoacrylate and the like.

  The proportion of the quaternary ammonium group-containing polymer in the entire nonvolatile content in the coating solution is usually 10% by weight or more, preferably 15% by weight or more, and more preferably 20% by weight or more. When the content is less than this, the antistatic performance may be insufficient. On the other hand, the upper limit is 90% by weight, preferably 80% by weight or less, and more preferably 60% by weight or less. When there is more content than this, the uniformity and external appearance of the coating film obtained may be inferior.

  Examples of the polyvalent aldehyde compound in the present invention include glyoxal, glutaraldehyde, terephthalaldehyde, cyclohexanedialdehyde, tricyclodecanedialdehyde, norbornanedialdehyde, and suberaldehyde. Further, those obtained by reacting these aldehyde groups with glycol or amide can also be used. In particular, a product obtained by reacting glyoxal with a polyhydric alcohol such as ethylene glycol or glycerin, a monosaccharide such as glucose or galactose, or a cyclic amide can be preferably used. These reactants suppress the reactivity of polyaldehyde at room temperature, and after coating and drying, glycols such as ethylene glycol and cyclic amides are removed, and the reaction of aldehyde starts in the coating layer, making it easy to handle. In addition, once the glycols such as ethylene glycol and the cyclic amide are removed, there are fewer free reactive residues due to their high reactivity, and there are advantages in terms of performance stability over time and safety and health.

  The coating solution for obtaining the undercoat layer of the present invention preferably contains polyvinyl alcohol. When the pressure-sensitive adhesive film having the undercoat layer thus obtained is heated, precipitation of the oligomer component from the base film tends to be further suppressed.

  The polyvinyl alcohol used in the present invention can be synthesized by a normal polymerization reaction and is preferably water-soluble.

  The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. When the degree of polymerization is 100 or less, the water resistance of the coating layer tends to decrease. The saponification degree of polyvinyl alcohol is not particularly limited, but a polyvinyl acetate saponified product that is usually 70 mol% or more, preferably 80 mol% or more and 99.9 mol% or less is practically used.

  In addition, it is preferable that the coating solution contains a thermosetting crosslinking component because the durability of the undercoat layer is improved. Examples of such cross-linking components include amino resin-based, isocyanate-based, oxazoline-based, and epoxy-based components. Also included are polymer-type cross-linking reactive compounds having reactive groups in other polymer skeletons. As a particularly preferred embodiment in the present invention, an amino resin-based crosslinking agent can be exemplified. Examples of amino resin-based crosslinking agents include alkylolized melamine-based, benzoguanamine-based, and urea-based agents. In particular, an amino film obtained by converting an amino group into methylol and further methylating a part of the methylol group is water-soluble, easy to handle, highly reactive, and provides a pressure-sensitive adhesive film with less oligomer precipitation from a base film.

  When such a crosslinking component is contained, a component for accelerating crosslinking, for example, a crosslinking catalyst can be used in combination.

  In the coating liquid for providing the undercoat layer, components other than those described above can be included as necessary. For example, surfactants, other binders, particles, antifoaming agents, coatability improvers, thickeners, antioxidants, ultraviolet absorbers, foaming agents, dyes, pigments and the like. These additives may be used alone or in combination of two or more as necessary.

  Further, the thickness of the undercoat layer is usually in the range of 0.003 μm to 1 μm as the film thickness on the biaxially stretched polyester film. Preferably it is 0.005 micrometer-0.5 micrometer, More preferably, it is the range of 0.01 micrometer-0.2 micrometer. When the thickness is smaller than this, the amount of oligomers precipitated from the film may not be sufficiently reduced. If it is thicker than this, problems such as deterioration of the appearance of the undercoat layer and easy blocking may occur.

  The thickness of the undercoat layer is determined by dyeing the coated film with a heavy metal such as a ruthenium compound or an osmium compound, adjusting the section of the coated film by an ultrathin section method, and then coating the section of the coated film with a transmission electron microscope. This can be confirmed by observing multiple layers and averaging the measured values.

  As a method for applying the coating solution to the polyester film, for example, a coating technique as shown in “Coating system” published by Yuji Harasaki, Tsuji Shoten, published in 1979 can be used. Specifically, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar coater And a technique such as an extrusion coater.

  In order to improve the applicability and adhesion of the coating agent to the film, the film may be subjected to chemical treatment, corona discharge treatment, plasma treatment or the like before coating.

  In the present invention, an adhesive layer is further provided on the undercoat layer of the film obtained as described above. Although there is no restriction | limiting in particular as how to provide this adhesion layer, The method of bonding the adhesion layer provided on the releasable base material to the undercoat layer of this invention, and the coating liquid containing an adhesion layer component There are methods such as direct application.

  In the method of bonding from a releasable base material, it is necessary to be concerned about bubbles and wrinkles entering when bonding, but there is an advantage that a process such as heat is not added to the final adhesive film is there. In particular, when another functional layer is provided on the surface of the adhesive film opposite to the adhesive layer, damage to the functional layer can be avoided.

  The direct application method is that when the adhesive layer is provided, the film is heated for drying and curing, and when a functional layer is provided on the opposite side of the adhesive layer, troubles in the processing step of providing the adhesive layer If the product is soiled by the above, there is a problem that the loss including the processing of the functional layer is caused and the economic disadvantage is increased, but there is an advantage that the obtained adhesive layer is uniform.

  Generally, it can be appropriately selected according to the configuration and purpose of the final product.

  Although there is no restriction | limiting in particular in the thickness of an adhesion layer, about 3-100 micrometers is preferable and about 5-40 micrometers is more preferable. If it is thinner than this, coating formation becomes difficult and the adhesive strength tends to be insufficient. If it is thicker than this range, the adhesive strength tends to be too high, and the cost tends to be disadvantageous.

  As the pressure-sensitive adhesive, it is possible to use generally known pressure-sensitive adhesives such as acrylic, silicone, rubber, and synthetic rubber. In particular, an acrylic pressure-sensitive adhesive is preferable because it has excellent transparency and heat resistance and can easily adjust the peeling force.

  As the base polymer of the acrylic pressure-sensitive adhesive, a (meth) acrylic acid alkyl ester copolymer is suitable. The alkyl group has an average carbon number of about 1 to 12, and examples include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like. These may be used alone or in combination. What has a C1-C9 alkyl group especially is preferable.

  Furthermore, one or more kinds of various monomers are introduced into the base polymer by copolymerization for the purpose of improving adhesiveness and heat resistance. Specific examples of such copolymerization monomers include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid 6 Hydroxyl group-containing monomers such as hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate Carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride Monomer-containing monomer; Caprolac of acrylic acid Adducts such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, etc. A sulfonic acid group-containing monomer, and a phosphoric acid group-containing monomer such as 2-hydroxyethylacryloyl phosphate. In addition, (N-substituted) amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Monomer; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid t-butylaminoethyl and other (meth) acrylic acid alkylaminoalkyl monomers; (meth) acrylic (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acid and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- ( (Meta) acryloyl- -Succinimide monomers such as oxyoctamethylene succinimide and N-acryloylmorpholine are also exemplified as examples of monomers for modification, and vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, Vinyl monomers such as vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic amides, styrene, α-methylstyrene, N-vinylcaprolactam; acrylonitrile, methacrylo Cyanoacrylate monomers such as nitriles; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; Polyethyleneglycol (meth) acrylate Glycol-based acrylic ester monomers such as (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol; (meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate Acrylic acid ester monomers such as silicone (meth) acrylate and 2-methoxyethyl acrylate can also be used.

  In particular, a carboxyl group-containing monomer such as acrylic acid is preferably used.

  The ratio of the copolymerization monomer in the acrylic polymer is not particularly limited, but is preferably about 0.1% to 10% in weight ratio.

  The pressure-sensitive adhesive is preferably a pressure-sensitive adhesive composition containing a crosslinking agent. Examples of the polyfunctional compound that can be incorporated into the pressure-sensitive adhesive include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, and an imine crosslinking agent. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable.

  The blending ratio of the base polymer such as an acrylic polymer and the crosslinking agent is not particularly limited, but usually, the crosslinking agent (solid content) is preferably about 0.01 to 10 parts by weight with respect to 100 parts by weight of the base polymer (solid content). Furthermore, about 0.1-5 weight part is preferable.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method in an Example and a comparative example is as follows.

(1) Measuring method of intrinsic viscosity of polyester 1 g of polyester was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) was added and dissolved, and the measurement was performed at 30 ° C.

(2) Measuring method of average particle size (d50: μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Coating layer thickness A film was fixed with an embedding resin, a cross section was cut with a microtome, and a sample was prepared by staining with 2% osmic acid at 60 ° C. for 2 hours. The obtained sample was observed with a transmission electron microscope (JEM2010 manufactured by JEOL Ltd.), and the thickness of the coating layer was measured. A total of 15 points on the film are measured, and an average of 9 points excluding 3 points from the larger value and 3 points from the smaller value is defined as the coating layer thickness.

(4) Surface resistivity value A high resistance measuring instrument manufactured by Hewlett-Packard Japan: HP4339B and measuring electrode: HP16008B were used, and the sample was sufficiently conditioned in a measurement atmosphere of 23 ° C. and 50% RH, and then 1 The surface resistivity of the measurement surface after the minute was measured.

(5) Dust adhesion evaluation (ash test)
After fully adjusting the pressure-sensitive adhesive film in a measurement atmosphere of 23 ° C. and 50% RH, the release film on the surface of the pressure-sensitive adhesive layer is peeled off, and then the pressure-sensitive adhesive layer is gently brought close to the finely crushed cigarette ash. The ash adhesion status was evaluated according to the following criteria.
○: Adhesion film does not adhere even when it is close to ash △: Adhesion film is slightly attached when it is close to ash ×: Adhesion film is attached in large quantities just by bringing it close to ash

(6) Adhesive layer optical defect inspection The release film of the adhesive film was peeled off, a sample was prepared by attaching the adhesive layer to a glass plate, and the sample was allowed to stand at 150 ° C. for 3 hours in a nitrogen atmosphere and subjected to heat treatment. Subsequently, the foreign material produced in the adhesive layer was examined under an optical microscope. In the inspection, an area of 100 mm × 100 mm was selected from 12 arbitrary positions of the sample, and the number of foreign matters having a size of 5 μm or more was counted. Except for the two inspection areas with the largest number of foreign objects, the number of foreign objects within the 10 inspection areas was determined according to the following criteria.
○: Foreign matter is not found △: Foreign matter is 1 or more and less than 3 (slightly problematic)
×: 3 or more foreign matters (problem in practical use)

The polyester used in the Examples and Comparative Examples is as follows.
(Polyester 1): 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol are used as starting materials, 0.09 part by weight of magnesium acetate tetrahydrate as a catalyst is taken in a reactor, the reaction start temperature is 150 ° C., and methanol The reaction temperature was gradually raised as the solvent was distilled off, and the temperature reached 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part of ethyl acid phosphate to this reaction mixture, 0.04 part of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.63 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester 1 was 0.63.

(Polyester 2): In the method for producing polyester 1, after adding 0.04 part of ethyl acid phosphate, 0.3 part of silica particles having an average particle diameter (d50) of 1.6 μm dispersed in ethylene glycol were added. Polyester 2 was obtained using the same method as the production method of polyester 1 except that 0.04 part of antimony oxide was added and the polycondensation reaction was stopped at a time corresponding to an intrinsic viscosity of 0.65. The obtained polyester 2 had an intrinsic viscosity of 0.65.

Moreover, the following was used as a composition contained in the coating liquid for providing an undercoat layer.
(E1): Copolymer having a weight ratio of 75/12/15/30 of 2- (trimethylamino) ethyl methacrylate / ethyl methacrylate / butyl methacrylate / polyethylene glycol-containing monoacrylate whose counter ion is methyl sulfonate.
(E2): A 2-hydroxy3-methacryloxypropyltrimethylammonium salt polymer in which the counter ion is methylsulfonate.
(E3): a polymer compound having a number average molecular weight of 20000, obtained by copolymerizing a structural unit of the following formula 1-1 and a structural unit of the following formula 1-2 at a weight ratio of 95/5.

(A1): Polyhydric aldehyde compound obtained by reacting glyoxal with anhydrous glucose (B1): Polyethylene glycol-containing monoacrylate polymer (B2) having a number average molecular weight of 20000: Polyvinyl alcohol having a saponification degree = 88 mol% and a polymerization degree of 500 (C1): Hexamethoxymethylolated melamine having a molar ratio of imino group / methylol group / methoxy group of 1.5 / 2 / 2.5 (F1): surface alumina-coated silica sol, average particle diameter of 15 nm by BET method

Comparative Example 1:
A blend of polyester 1 and polyester 2 at a weight ratio of 90/10 was used as a raw material for layer A, and polyester 1 alone was used as a raw material for layer B. And heat-melting, layer A is divided into two layers, the outer layer (surface layer) is co-extruded in a layer configuration of two types and three layers (layer A / layer B / layer A) with the layer B as an intermediate layer, electrostatic adhesion method Is used to cool and solidify while adhering to a mirror surface cooling drum having a surface temperature of 40 to 50 ° C., and the thickness composition ratio becomes A layer / B layer / A layer = 2.5 / 45 / 2.5, unstretched polyethylene terephthalate A film was created. This film was stretched 3.7 times in the longitudinal direction while passing through a heating roll group at 85 ° C. to obtain a uniaxially oriented film. Next, this film was guided to a tenter stretching machine, stretched 4.0 times in the width direction at 100 ° C., and further subjected to heat treatment at 230 ° C., followed by a 2% relaxation treatment in the width direction, and a film thickness of 50 μm. An axially oriented polyethylene terephthalate film was obtained. The properties of this film are shown in Table 2.

  Furthermore, an isocyanate-based crosslinking agent is used for a solution of an acrylic polymer having a weight average molecular weight of 2 million comprising a copolymer of butyl acrylate / acrylic acid / 2-hydroxyethyl acrylate in a weight ratio of 100/6 / 0.1. A certain Nippon Polyurethane Coronate L, Shin-Etsu Chemical Co., Ltd. silane coupling agent KBM403, and ethyl acetate were added to prepare a pressure-sensitive adhesive solution having a solid content concentration of 10%. In terms of solid content in the solution, acrylic copolymer / coronate L / KBM403 = 100/3 / 0.6.

  This pressure-sensitive adhesive solution was applied and dried on a release film MRF38 manufactured by Mitsubishi Plastics so that the thickness after drying was 25 μm. This release film with an adhesive layer was bonded to a biaxially stretched polyester film to obtain an adhesive film with a release film. The properties of this adhesive film are shown in Table 3 below.

Examples 1-9, Comparative Examples 2-4:
A coating solution as shown in Table 1 below was applied to one side of a uniaxially oriented film obtained in the same process as Comparative Example 1. Next, the film was guided to a tenter stretching machine, and the coating composition was dried using the heat, and the film was formed on a biaxially oriented polyethylene terephthalate film having a film thickness of 50 μm by the same process as in Comparative Example 1. A laminated polyester film provided with a coating layer having a thickness of 1 or shown in Table 2 below was obtained. The properties of this film are shown in Table 3. In addition, the surface specific resistance value in Table 3 is a numerical value obtained by measuring the obtained coating layer surface.

  Further, in the same manner as in Comparative Example 1, an adhesive film with a release film having an undercoat layer between the polyester film and the adhesive layer is bonded to the coating layer of the biaxially stretched polyester film. Obtained. The properties of this adhesive film are shown in Table 3.

  However, the weight ratios in Table 1 and Table 2 below represent the weight ratio of each component in the coating solution.

  The film of the present invention can be suitably used as an adhesive film in applications that require excellent antistatic properties and the ability to prevent foreign matters from being generated in the adhesive layer even after exposure to high temperatures.

Claims (4)

A base material composed of a biaxially stretched polyester film is coated with a coating solution containing a quaternary ammonium group-containing polymer and a polyvalent aldehyde compound, and has an undercoat layer obtained by drying, on the undercoat layer An adhesive film, wherein an adhesive layer is laminated. The pressure-sensitive adhesive film according to claim 1, wherein the quaternary ammonium group-containing polymer is a polymer obtained by copolymerizing polyethylene glycol-containing (meth) acrylate. The pressure-sensitive adhesive film according to claim 1 or 2, wherein the coating solution contains a polyethylene glycol-containing (meth) acrylate polymer. The pressure-sensitive adhesive film according to claim 1, wherein the coating solution contains polyvinyl alcohol.