JP4956384B2 - Protective film for display screen and manufacturing method thereof - Google Patents

Description

  The present invention relates to a protective film for a display screen of an image display device and a method for producing the same. Specifically, the adhesive film has an adhesive layer excellent in sticking property and removability. A protective film for a display screen, which has excellent hot water adhesion, the peel strength between the pressure-sensitive adhesive layer and the separate film is appropriately controlled, the transparency is high, and the reduction in the sharpness of the image on the display screen is suppressed, and its It relates to a manufacturing method.

  A pressure-sensitive adhesive sheet having a silicone rubber layer as a pressure-sensitive adhesive layer has excellent adhesion and removability, and is therefore used in a wide range of fields as a pressure-sensitive adhesive sheet that requires removability (repairability). Various films including a protective film for a display screen having a silicone adhesive layer using a silicone rubber compound as a raw material have already been disclosed by the present inventors (see, for example, Patent Documents 1 to 7).

  The film described in each patent document is suitably used in various applications. However, in recent years, along with the spread of its applications, there are cases where it does not satisfy the market requirements for quality and price, and improvements have been demanded.

  For example, when a display screen protective film is used as a touch panel member, in car navigation applications and the like, the temperature inside the vehicle varies considerably from a low temperature to a high temperature, so it is necessary to withstand severe conditions of use. There was room for improvement in the durability of adhesion between the film and the substrate film.

  In addition, the above display screen protective film is shipped in a form in which a separate film is laminated on the surface of the adhesive layer in order to improve its handleability. When actually used, the separate film is peeled off and attached to the target article. However, depending on the application, there is a strong demand for reducing the peeling force. However, if the peel strength of the separate film is too small, when the pressure-sensitive adhesive sheet is wound up in the manufacturing process of the protective film for display screen, partial separation of the separate film occurs, and the air is perpendicular to the sheet winding direction. In some cases, a so-called channeling phenomenon in which a layer enters was generated. Further, in optical applications, a high transparency and stability of the protective film for display screens are required, but there is a problem that it is difficult to cope with them.

Further, the raw material of the silicone rubber disclosed in the above patent document is a millable type silicone rubber compound, but such a compound has a reduced solubility in a solvent depending on its storage state, and the silicone rubber layer May be deteriorated in appearance quality due to undissolved material. In addition, the coating liquid in which the silicone rubber compound is dissolved in a solvent has various problems in quality stabilization and stable production, such as gelation of the solution depending on the storage state, and it cannot be used as the coating liquid. It has become an obstacle to answering the demand for cost reduction, and the resolution of these problems is strongly envyed.
JP-A-11-320762 JP 2000-56694 A JP 2001-83886 A JP 2001-139903 A JP 2003-263115 A JP 2004-163636 A JP 2007-47954 A

  Therefore, in the present invention, the adhesion between the silicone pressure-sensitive adhesive layer and the base film is excellent, in particular, heat-resistant water adhesion, the peeling force between the silicone pressure-sensitive adhesive layer and the separate film is appropriately controlled, and the transparency is high and the visibility of the display screen is high. The problem was to provide an excellent protective film for display screen and to provide a method for efficiently and economically manufacturing the protective film for display screen.

  The protective film for a display screen of the image display device of the present invention that has solved the above problems is a polyester base film (A), a heat resistant water adhesion improving layer (B), and a crosslinked silicone compound having a polydimethylsiloxane skeleton. The protective film for a display screen in which the adhesive layer (C), the release layer (D) and the separate film (E) are laminated in the order of A to E, and measured by the method defined in the specification. The main point is that the peel strength between the adhesive layer (C) and the release layer (D) is 0.03 to 1.0 N / 20 mm.

  Moreover, it is preferable that the said adhesion layer (C) is a thing which does not peel when evaluating the heat-resistant water adhesiveness defined by the method mentioned later.

  The release layer (D) is preferably made of a non-silicone compound, and the release layer (D) is a layer containing a binder resin, a polymer wax component and an antistatic agent. Is desirable. Moreover, it is more preferable that the crosslinked silicone compound constituting the adhesive layer (C) is a crosslinked silicone compound having a polydimethylsiloxane skeleton having a number average molecular weight of 50,000 to 500,000.

  The thickness of the heat resistant water adhesion improving layer (B) is preferably 0.01 to 0.5 μm, and the heat resistant water adhesion improving layer (B) is selected from the group consisting of polyester, polyurethane and acrylic polymers. It is desirable to include a reaction product of one or more selected polymers and a crosslinking agent.

  Further, as the crosslinking agent, melamine crosslinking agent, oxazoline crosslinking agent, isocyanate crosslinking agent, aziridine crosslinking agent, epoxy crosslinking agent, methylolated or alkylolized urea crosslinking agent, acrylamide crosslinking agent, It is recommended that it is at least one selected from the group consisting of polyamide resins, amide epoxy compounds, silane coupling agents and titanate coupling agents. Further, the heat resistant water adhesion improving layer (B) may include a self-crosslinked one or more types of self-crosslinked polymers selected from the group consisting of self-crosslinked polyester, polyurethane and acrylic polymers. Good.

There are several methods of the present invention for producing the protective film for display screen as described later, but if one representative example is shown,
A step of laminating the heat resistant water adhesion improving layer (B) on one side of the polyester base film (A) to form a laminate (1);
A step of laminating a layer containing an uncrosslinked product of a silicone compound having a polydimethylsiloxane skeleton on the surface of the heat resistant water adhesion improving layer (B) of the laminate (1) to form a laminate (2);
A step of laminating the release layer (D) on one side of the polyester film (E) to form a laminate (3);
The laminates (2) and (3) are formed so that the release layer (D) of the laminate (3) is in contact with the surface of the layer (2) containing an uncrosslinked silicone compound having a polydimethylsiloxane skeleton. ) And forming a laminate (4),
A step of crosslinking a non-crosslinked body of the silicone compound having a polydimethylsiloxane skeleton of the laminate (4) to form a laminate (4 ′) having an adhesive layer (C);
Including the gist.

  Further, the layer containing only a crosslinked product of the silicone compound containing the polydimethylsiloxane skeleton has a silicone compound having a number average molecular weight of 50,000 to 500,000 as a main component, and a polyhydric alcohol acrylic as an adhesion improver. It is preferably formed from a composition containing at least one of an acid ester and a polyhydric alcohol methacrylate.

  The protective film for display screens of the present invention is formed with an adhesive layer containing a cross-linked silicone compound of a polydimethylsiloxane skeleton that has both adhesive properties and removability, so even when an adhesive error occurs It can be easily peeled off and reattached. Moreover, since the protective film for display screens of this invention has the high transparency, it can be used conveniently also as a surface protective film for optical members.

  Furthermore, since the protective film for display screens of the present invention is provided with the heat resistant water adhesion improving layer (B) between the pressure-sensitive adhesive layer and the base polyester film, it has excellent adhesion durability under severe conditions. It can use suitably also as a protective film for display screens used. In addition, the peeling force of the separate film laminated on the surface of the silicone adhesive layer is controlled to an appropriate range, and the above-described channeling phenomenon occurs even in the process of winding up the protective film for display screen during manufacturing. Therefore, it is possible to stably produce a high-quality protective film for display screen.

  The manufacturing method of the protective film for display screens of this invention can manufacture the protective film for display screens which has the said characteristic economically. In particular, since the adhesive layer is formed by crosslinking an uncrosslinked polydimethylsiloxane skeleton silicone compound, it is more transparent than a silicone rubber layer made from a conventionally known millable silicone rubber compound. In addition, since it is excellent in clarity and operability, it has a feature that it is excellent in cost performance as compared with a conventionally known method.

  The protective film for a display screen of the image display device of the present invention includes a polyester base film (A), a heat resistant water adhesion improving layer (B), and an adhesive layer (C) made of a crosslinked silicone compound having a polydimethylsiloxane skeleton. ), The release layer (D) and the separate film (E) include a laminate in which A to E are laminated in order, and the adhesive layer (C) and the release layer (D) measured by the method described later The delamination force is 0.03 to 1.0 N / 20 mm.

[Polyester base film (A) and polyester film (E)]
The polyester base film (A) and the polyester film (E) can be arbitrarily used as long as the main component (80% by mass or more) is polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, or the like. In particular, a biaxially stretched one is desirably used. The production method of the biaxially stretched polyester film is not particularly limited. For example, after drying the polyester as necessary, it is supplied to a known melt extruder, extruded into a sheet form from a slit die, and electrostatically applied. It is sufficient that the unstretched sheet is stretched after being brought into close contact with the casting drum by a method such as the above, cooled and solidified to obtain an unstretched sheet. The biaxial stretching method may be either simultaneous biaxial stretching or sequential biaxial stretching.

  The polyester-based substrate film (A) may be subjected to known adhesion improving treatment such as corona treatment, frame treatment, plasma treatment and the like.

  Moreover, it is a preferable embodiment that the polyester-based substrate film (A) is subjected to a surface treatment for imparting characteristics necessary for use as a display screen protective film. For example, hard coat layer for preventing scratches on the surface, antireflection layer for preventing reflection of external light, light diffusion layer, antifouling layer for preventing adhesion of fingerprints and improving wiping property, and suppressing the growth of fungi Lamination | stacking, such as an antimicrobial layer etc. (or killed) etc., and the functional layer which combined or laminated | stacked these, is mentioned.

[Heat resistant water adhesion improving layer (B)]
The heat resistant water adhesion improving layer (B) is a layer provided on the surface of the polyester base film (A), and the adhesive layer (C) is not peeled in the evaluation of the heat resistant water adhesion described later. Is a layer. The thickness of the heat resistant water adhesion improving layer (B) is preferably 0.01 to 0.5 μm. If the thickness of the heat resistant water adhesion improving layer (B) is 0.01 to 0.5 μm, good heat resistant water adhesion is exhibited, but it is preferable because the heat resistant water adhesion may be difficult to obtain outside the above range. Absent. A more preferable thickness range is 0.03 to 0.4 μm, and 0.05 to 0.3 μm is even more preferable.

  Preferred as the heat resistant water adhesion improving layer (B) is a cross-linked polymer layer (cross-linked polymer layer), which is a layer obtained by cross-linking a polymer with a cross-linking agent or a layer using a self-cross-linking polymer There is.

  The polymer that can be used in the method of crosslinking with a crosslinking agent is not particularly limited, but is preferably at least one selected from the group consisting of polyesters, polyurethanes, and acrylic polymers. The above polymers may be used alone or in combination of two or three different types.

[Polyester for heat resistant water adhesion improving layer (B)]
The polyester has an ester bond in the main chain or side chain, and is obtained by polycondensation of polyvalent carboxylic acid and glycol.

  As the polyvalent carboxylic acid component constituting the polyester, aromatic, aliphatic, and alicyclic dicarboxylic acids, trivalent or higher polyvalent carboxylic acids, and ester derivatives thereof can be used.

  Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxy Ethane-p, p′-dicarboxylic acid, phenylindanedicarboxylic acid and the like can be used. From the viewpoint of the strength and heat resistance of the heat resistant water adhesion improving layer (B), these aromatic dicarboxylic acids are preferably 30 mol% or more, more preferably 35 mol% or more in 100 mol% of the polyvalent carboxylic acid component, More preferably, it is preferable to use polyester occupying 40 mol%.

  Examples of the aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like, and ester-forming derivatives thereof can be used.

  Examples of the glycol component of polyester include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, , 6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol Neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2, 4-trimethyl-1,6-hexanediol, 1,2-cyclo Xanthodimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4′-thiodiphenol, bisphenol A, 4,4′-methylenediphenol, 4,4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o-, m- and p-dihydroxybenzene, 4,4′-isopropylidenephenol, 4,4′-isopropylidenevindiol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and the like can be used.

  In addition, when using polyester as an aqueous liquid as a coating liquid, a compound containing a carboxylic acid (salt) group or a compound containing a sulfonic acid (salt) group is used to facilitate water-solubilization or water-dispersion of the polyester. It is preferable to copolymerize a compound containing a phosphonic acid (salt) group.

  Examples of the compound containing a carboxylic acid (salt) group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1 , 2,3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 5- (2,5-dioxotetrahydro Furfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-1,2-dicarboxylic acid, cyclopentanetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bistrimellite 2,2 ′, 3,3′-diphenyltetracarboxylic acid, thiophene-2,3,4,5-tetracarboxylic acid, ethylenetetracarboxylic acid, etc., or alkali metal salts, alkaline earth metal salts thereof, An ammonium salt etc. can be mentioned.

  Examples of the compound containing a sulfonic acid (salt) group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo-1,4-bis (hydroxyethoxy) benzene or the like, or an alkali metal salt, alkaline earth metal salt, or ammonium salt thereof can be used.

  Examples of the compound containing a phosphonic acid (salt) group include phosphoterephthalic acid, 5-phosphoisophthalic acid, 4-phosphoisophthalic acid, 4-phosphonaphthalene-2,7-dicarboxylic acid, phospho-p-xylylene glycol, 2-phospho-1,4-bis (hydroxyethoxy) benzene or the like, or an alkali metal salt, alkaline earth metal salt, or ammonium salt thereof can be used.

  In the present invention, for example, a modified polyester copolymer such as a block copolymer or a graft copolymer modified with acrylic, urethane, epoxy, or the like can be used as the polyester.

  Preferred polyesters include those selected from terephthalic acid, isophthalic acid, sebacic acid, 5-sodium sulfoisophthalic acid as the acid component, and ethylene glycol, diethylene glycol, 1,4-butanediol, and neopentyl glycol as the glycol component. And the like. When water resistance is required, a copolymer or the like containing trimellitic acid as its copolymer component can be suitably used instead of 5-sodium sulfoisophthalic acid.

  The polyester can be produced by the following production method. For example, a polyester having a dicarboxylic acid component consisting of terephthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid and a glycol component consisting of ethylene glycol and neopentyl glycol can be directly esterified with these monomers. Or it can manufacture by the method etc. which manufacture by the 1st step which transesterifies, and the 2nd step which carries out the polycondensation reaction of the reaction product of this 1st step.

  At this time, for example, alkali metal, alkaline earth metal, manganese, cobalt, zinc, antimony, germanium, titanium compound, or the like can be used as the reaction catalyst.

  Further, as a method for obtaining a polyester having many carboxyl groups at the terminal and / or side chain, JP-A-54-46294, JP-A-60-209073, JP-A-62-240318, JP JP 53-26828, JP 53-26829, JP 53-98336, JP 56-116718, JP 61-124684, JP 62-240318 Although it can be produced by copolymerizing a trivalent or higher polyvalent carboxylic acid described in a publication or the like, it is needless to say that other methods may be used.

  Further, as the water-dispersed polyester resin, for example, a commercially available “Vaironal (registered trademark)” series (manufactured by Toyobo Co., Ltd.) can be used.

  The intrinsic viscosity of the polyester is not particularly limited, but is preferably 0.3 dl / g or more in terms of adhesiveness, more preferably 0.35 dl / g or more, and most preferably 0.4 dl / g or more. It is. The glass transition temperature (hereinafter sometimes abbreviated as Tg) of the polyester is preferably 0 to 130 ° C, more preferably 10 to 85 ° C. Use of polyester with a Tg of 0 ° C. or higher improves heat resistant water adhesion, and when the heat resistant water adhesion improved layer (B) is laminated on the surface of the polyester-based substrate film (A) and then wound up once Such a blocking phenomenon can be suppressed. Moreover, stability and water dispersibility can be favorably maintained by using polyester with Tg of 130 ° C. or lower.

[Polyurethane for heat resistant water adhesion improving layer (B)]
Next, polyurethane will be described. The polyurethane is not particularly limited as long as it has a urethane bond, and the main component is obtained by polymerizing a polyol compound and a polyisocyanate compound.

  Examples of the polyol compound include polyethylene glycol, polypropylene glycol, polyethylene / propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene. Adipate, polytetramethylene adipate, trimethylolpropane, trimethylolethane, glycerin, acrylic polyol and the like can be used.

  Examples of the polyisocyanate compound include tolylene diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, an adduct of hexamethylene diisocyanate and trimethylolethane, and the like. it can.

  In the synthesis of the polyurethane, a known chain extender, a crosslinking agent, and the like may be included in addition to the polyol compound and the polyisocyanate compound. As the chain extender or crosslinking agent, ethylene glycol, propylene glycol, butanediol, diethylene glycol, ethylenediamine, diethylenetriamine, or the like can be used.

  In order to obtain a stable polyurethane water dispersion, it is preferable to synthesize polyurethane having an increased affinity for water. Specifically, an appropriate amount of anionic groups may be introduced into the polyurethane. For example, a method of using a compound having an anionic group for polyol, polyisocyanate, chain extender, etc., a method of reacting an unreacted isocyanate group of the produced polyurethane with a compound having an anionic group, or having an active hydrogen of polyurethane It can be produced by a method of reacting a group with a specific compound.

  The anionic group in the polyurethane is preferably used as a sulfonic acid group, a carboxylic acid group, and an ammonium salt, lithium salt, sodium salt, potassium salt or magnesium salt thereof. In particular, a sulfonate group is preferable.

  The amount of the unit having an anionic group in the polyurethane is preferably 0.05% by mass to 15% by mass from the viewpoint of water dispersibility of the polyurethane.

  For example, as a polyurethane water dispersion, “Hydran (registered trademark)” series (manufactured by Dainippon Ink & Chemicals, Inc.) can be used.

[Acrylic polymer for heat resistant water adhesion improving layer (B)]
Examples of the monomer component constituting the acrylic polymer include, for example, alkyl acrylate, alkyl methacrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and t-butyl groups. Hydroxy group-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate), 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.) ; (Meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-phenyl (meth) acrylamide, etc. Mido group-containing monomer; amino group-containing monomer such as N, N-diethylaminoethyl (meth) acrylate; epoxy group-containing monomer such as glycidyl (meth) acrylate; (meth) acrylic acid and salts thereof (lithium salt, sodium salt, A monomer containing a carboxyl group such as potassium salt or the like or a salt thereof can be used, and these are (co) polymerized using one kind or two or more kinds. Furthermore, these can be used in combination with other types of monomers.

  Examples of other types of monomers include epoxy group-containing monomers such as allyl glycidyl ether; sulfonic acids such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.) Monomer containing a group and a salt thereof; a monomer containing a carboxyl group or a salt thereof such as crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.) Monomers containing acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoe Ether, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, may be used vinyl chloride.

  Moreover, as said acrylic polymer, a modified acrylic polymer, for example, a block copolymer modified with polyester, polyurethane, epoxy resin, etc., a graft copolymer, etc. can be used.

  The lower limit of Tg of the acrylic polymer is preferably −10 ° C., more preferably 0 ° C., and most preferably 10 ° C. from the viewpoint of hot water adhesion and blocking resistance. On the other hand, the upper limit of Tg of the acrylic polymer is preferably 90 ° C., more preferably 50 ° C., and most preferably 40 ° C. from the viewpoints of heat resistant water adhesion and film-forming properties. If the Tg is too low, the hot water adhesion tends to be difficult to obtain or tends to block, while if too high, the adhesiveness and film-forming property may decrease. Further, the weight average molecular weight (Mw) of the acrylic polymer is preferably 50,000 or more, and more preferably 300,000 or more from the viewpoint of heat resistant water adhesion.

  Preferable examples of the acrylic polymer include copolymers composed of monomers selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, and acrylic acid.

  It is preferable to dissolve, emulsify, or suspend an acrylic polymer in water and use it as an aqueous liquid from the viewpoint of environmental pollution and explosion-proof properties during coating. Such water-based acrylic polymers are copolymerized with monomers having a hydrophilic group (acrylic acid, methacrylic acid, acrylamide, vinyl sulfonic acid and salts thereof, etc.) and emulsion polymerization using reactive emulsifiers and surfactants, It can be prepared by a method such as suspension polymerization or soap-free polymerization.

  Commercially available acrylic emulsions may also be used, for example, “Jonkrill (registered trademark)” series (manufactured by BASF Japan).

[Crosslinking agent used for heat resistant water adhesion improving layer (B)]
In the present invention, the polyester, polyurethane and acrylic polymer are preferably crosslinked. When the above polymer is cross-linked using a cross-linking agent, as the cross-linking agent, a functional group present in the above-described polymer, such as a carboxyl group, a hydroxyl group, a methylol group, an amide group, or the like can be used. Good. For example, melamine-based crosslinking agent, oxazoline-based crosslinking agent, isocyanate-based crosslinking agent, aziridine-based crosslinking agent, epoxy-based crosslinking agent, methylolized or alkylolized urea-based crosslinking agent, acrylamide-based crosslinking agent, polyamide-based resin, amide epoxy A compound, various silane coupling agents, various titanate coupling agents, etc. can be used. In particular, a melamine-based crosslinking agent and an oxazoline-based crosslinking agent can be suitably used from the viewpoints of compatibility with the above-described polymer, heat resistant water adhesion, and the like.

  The melamine-based crosslinking agent is not particularly limited, but is a melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting a methylolated melamine with a lower alcohol, or these A mixture of the above can be used. Moreover, as a melamine type crosslinking agent, a monomer, the condensate which consists of a multimer more than a dimer, a mixture thereof, etc. can be used. As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be used. Methylated melamine resins such as methylated trimethylol melamine and butylated hexamethylol melamine are preferred. Furthermore, in order to accelerate | stimulate the thermosetting of a melamine type crosslinking agent, you may use acidic catalysts, such as p-toluenesulfonic acid, for example.

  Further, the oxazoline-based crosslinking agent is not particularly limited as long as it has an oxazoline group as a functional group in the compound, but includes at least one monomer containing an oxazoline group, and at least one kind of What consists of an oxazoline group containing copolymer obtained by copolymerizing another monomer is preferable.

  Monomers containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like can be used, and one or a mixture of two or more thereof can also be used. Of these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

  In the oxazoline group-containing copolymer, the at least one other monomer used together with the oxazoline group-containing monomer is not particularly limited as long as it is a monomer copolymerizable with the oxazoline group-containing monomer. (Meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid Unsaturated nitriles such as (meth) acrylonitrile; unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; methyl vinyl ether and ethyl vinyl ether vinyl Ethers; olefins such as ethylene and propylene; halogen-containing α, β-unsaturated monomers such as vinyl chloride, vinylidene chloride and vinyl fluoride; α, β-unsaturated aromatics such as styrene and α-methylstyrene Monomers etc. can be used and these can use 1 type, or 2 or more types of mixtures.

  As the oxazoline group-containing polymer, for example, “Epocross (registered trademark)” series (manufactured by Nippon Shokubai Co., Ltd.) is available.

  The isocyanate-based crosslinking agent is not particularly limited as long as it has an isocyanate group as a functional group in the compound, but it is preferable to use a polyfunctional isocyanate compound containing two or more isocyanate groups in one molecule.

  As the polyfunctional isocyanate compound, a low-molecular or high-molecular aromatic or aliphatic diisocyanate or a trivalent or higher polyisocyanate can be used. Examples of the polyisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds. Furthermore, an excess amount of these isocyanate compounds and low molecular active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, or polyester polyols, poly The terminal isocyanate group containing compound obtained by making it react with polymer active hydrogen compounds, such as ether polyols and polyamides, can be mentioned.

  In addition, when using an isocyanate compound as a crosslinking agent, it is also possible to use a block type isocyanate compound. The blocked isocyanate can be prepared by subjecting the isocyanate compound and the blocking agent to an addition reaction by a conventionally known method. Examples of the isocyanate blocking agent include phenols such as phenol, cresol, xylenol, resorcinol, nitrophenol and chlorophenol; thiophenols such as thiophenol and methylthiophenol; oximes such as acetoxime, methylethylketoxime and cyclohexanone oxime; Alcohols such as methanol, ethanol, propanol and butanol; halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol; -Lactams such as caprolactam, δ-valerolactam, γ-butyrolactam, β-propyllactam; aromatic amines; imides; acetylacetone, acetoacetate, malonic acid Active methylene compounds such as glycol ester; mercaptans; imines; ureas; diaryl compounds; can be mentioned sodium bisulfite and the like.

  The epoxy-based crosslinking agent is not particularly limited as long as it has an epoxy group as a functional group in the compound. However, it is preferable to use a polyfunctional epoxy compound having two or more epoxy groups in one molecule. .

  Examples of the polyfunctional epoxy compound include diglycidyl ether of bisphenol A and oligomer thereof, diglycidyl ether of hydrogenated bisphenol A and oligomer thereof, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-oxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, propylene Glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and Polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-diglycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol triglycidyl Examples include ether, triglycidyl ether of glycerol alkylene oxide adduct, and the like.

  As the cross-linking agent, a phenol formaldehyde resin of a condensate with formaldehyde such as alkylated phenols and cresols; an adduct of urea, melamine, benzoguanamine and the like with formaldehyde, this adduct and an alcohol having 1 to 6 carbon atoms An amino resin such as an alkyl ether compound consisting of can also be used.

  Examples of the phenol formaldehyde resin include alkylated (methyl, ethyl, propyl, isopropyl or butyl) phenol, p-tert-amylphenol, 4,4′-sec-butylidenephenol, p-tert-butylphenol, o-, m-, p-cresol, p-cyclohexylphenol, 4,4'-isopropylidenephenol, p-nonylphenol, p-octylphenol, 3-pentadecylphenol, phenol, phenyl-o-cresol, p-phenylphenol, xylenol, etc. And the condensates of phenols and formaldehyde.

  Examples of amino resins include methoxylated methylol urea, methoxylated methylol N, N-ethylene urea, methoxylated methylol dicyandiamide, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol benzoguanamine, and the like. However, preferably, methoxylated methylol melamine, butoxylated methylol melamine, methylolated benzoguanamine and the like can be mentioned.

  The polymer (polyester, polyurethane, acrylic polymer) and the crosslinking agent can be mixed and used in an arbitrary ratio. However, in order to express the hot water adhesive effect of the present invention more remarkably, the crosslinking agent is: The addition of 2 to 50 parts by mass with respect to 100 parts by mass of the polymer is preferred, more preferably 3 to 25 parts by mass. When the addition amount of the crosslinking agent is less than 2 parts by mass, the effect of addition is small, and when it exceeds 50 parts by mass, the hot water resistant adhesiveness tends to be lowered.

[Self-crosslinking polymer of heat resistant water adhesion improving layer (B)]
In the present invention, in addition to the above method, for example, the heat resistant water adhesion improving layer (B) may be formed using a self-crosslinking type polymer in which a crosslinkable functional group is introduced into the above-described polymer. In the case of using a self-crosslinking type polymer, the crosslinking method may be, for example, thermal crosslinking, or may be crosslinking with high energy active rays such as ultraviolet rays, electron beams and γ rays.

  Hereinafter, a specific method will be illustrated for the case of polyester as the self-crosslinking polymer.

  The self-crosslinking type polyester preferably used in the present invention is a polyester graft copolymer obtained by grafting a hydrophobic copolymer polyester with a compound having at least one radical polymerizable double bond. The “grafting” of the polyester-based graft copolymer in the present invention is to introduce a branched polymer made of a polymer different from the main chain into the backbone polymer which is the main chain. Graft polymerization is usually carried out by reacting at least one radically polymerizable monomer using a radical initiator in a state where a hydrophobic copolyester is dissolved in an organic solvent. Hydrophobic copolyesters are essentially water-insoluble polyesters that do not inherently dissolve in water, so they are more heat resistant than using polyester resins that are soluble in water as the backbone polymer for graft polymerization. Excellent water adhesion.

  The hydrophobic copolyester is composed of 60 to 99.5 mol% of aromatic dicarboxylic acid, 0 to 39.5 mol% of aliphatic dicarboxylic acid and / or alicyclic dicarboxylic acid in 100 mol% of dicarboxylic acid component, radical It is preferable that the dicarboxylic acid containing a polymerizable double bond is 0.5 to 10 mol%. More preferably, the aromatic dicarboxylic acid is 68 to 98 mol%, the aliphatic dicarboxylic acid and / or the alicyclic dicarboxylic acid is 0 to 30 mol%, and the dicarboxylic acid containing a radical polymerizable unsaturated double bond is 2 to 2 mol. 7 mol%.

  When the aromatic dicarboxylic acid is 60 mol% or more and the aliphatic dicarboxylic acid and / or alicyclic dicarboxylic acid is 39.5 mol% or less, the heat resistant water adhesion is good. Moreover, the grafting of the radically polymerizable monomer with respect to the polyester resin can be efficiently performed by using 0.5 mol% or more of the dicarboxylic acid containing a radically polymerizable double bond. On the other hand, the content of 10 mol% or less is preferable because the viscosity of the reaction solution can be prevented from significantly increasing in the later stage of the grafting reaction, and the reaction can proceed uniformly.

  As the aromatic dicarboxylic acid, aliphatic and / or alicyclic dicarboxylic acid, any of the compounds exemplified above can be used. Examples of the dicarboxylic acid containing a radical polymerizable double bond include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid and other α, β-unsaturated dicarboxylic acids; 2,5-norbornene dicarboxylic acid anhydride, Examples thereof include alicyclic dicarboxylic acids containing unsaturated double bonds such as tetrahydrophthalic anhydride. From the viewpoint of polymerizability, fumaric acid, maleic acid, and 2,5-norbornene dicarboxylic acid are preferable among these dicarboxylic acids containing a polymerizable unsaturated double bond.

  As the glycol component, any of the compounds exemplified above can be used. Two or more glycol components may be used in combination. Especially, C2-C10 aliphatic glycol, C6-C12 alicyclic glycol, etc. are preferable.

  The hydrophobic copolymerized polyester may be copolymerized with 0 to 5 mol% of a trifunctional or higher polycarboxylic acid and / or polyol. The tri- or higher functional polycarboxylic acid includes (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) benzophenone tetracarboxylic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anne) Hydrotrimellitate) and the like. As the trifunctional or higher functional polyol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, or the like is used.

  The tri- or higher functional polycarboxylic acid and / or polyol is copolymerized in the range of 0 to 5 mol%, preferably 0 to 3 mol%, based on the total acid component or the total glycol component. Gelation can be suppressed.

  In addition, the lower limit of the weight average molecular weight of the hydrophobic copolyester is preferably 5,000 from the viewpoint of heat resistant water adhesion. Moreover, it is preferable that an upper limit is 50,000 at points, such as gelatinization at the time of superposition | polymerization.

  After synthesizing the hydrophobic copolyester, graft polymerization is performed. Graft polymerization is carried out by reacting at least one radical polymerizable monomer using a radical polymerization initiator in a state where the hydrophobic copolyester is dissolved in an organic solvent. The reaction product after completion of the grafting reaction is not limited to the graft copolymer of the desired hydrophobic copolymerized polyester and the radically polymerizable monomer, but also the hydrophobic copolymerized polyester and the hydrophobic copolymer that were not subjected to grafting. It also contains a (co) polymer obtained from a radically polymerizable monomer that has not been grafted to the polyester. The polyester-based graft copolymer in the present invention includes not only the above-described polyester-based graft copolymer, but also a hydrophobic copolymerized polyester that has not been grafted, and a radically polymerizable monomer that has not been grafted. Also included is a reaction mixture comprising the resulting (co) polymer and monomer (residual monomer).

In the present invention, the acid value of a reaction product obtained by graft polymerization of a radically polymerizable monomer to a hydrophobic copolymerized polyester is preferably 600 eq / 10 ⁶ g or more from the viewpoint of heat resistant water adhesion. More preferably, the acid value of the reactant is 1200 eq / 10 ⁶ g or more. When the acid value of the reaction product is less than 600 eq / 10 ⁶ g, the hot water adhesion may be lowered.

  The mass ratio of the desired hydrophobic copolymerized polyester and the radical polymerizable monomer suitable for the purpose of the present invention is preferably in the range of polyester / radical polymerizable monomer = 40/60 to 95/5, more preferably 55/45. ~ 93/7, most desirably in the range of 60/40 to 90/10.

  By setting the mass ratio of the hydrophobic copolyester to 40% by mass or more, the excellent adhesiveness of the polyester can be exhibited. On the other hand, when the mass ratio of the hydrophobic copolymerized polyester is 95% by mass or less, the blocking resistance can be improved and the acid value of the reaction product can be adjusted to the above range.

  The graft polymerization reaction product is in the form of an organic solvent solution or dispersion or an aqueous solvent solution or dispersion. In particular, a dispersion of an aqueous solvent, that is, a form of an aqueous dispersion is preferable in terms of working environment and applicability. Therefore, as the radical polymerizable monomer to be grafted, it is preferable to use a radical polymerizable monomer that essentially contains a hydrophilic radical polymerizable monomer. And after carrying out the graft polymerization in an organic solvent, the aqueous dispersion can be obtained by distilling off the organic solvent and adding water.

  The hydrophilic radical polymerizable monomer means a radical polymerizable monomer having a hydrophilic group or a group that can be changed to a hydrophilic group later. Examples of the radical polymerizable monomer having a hydrophilic group include a radical polymerizable monomer containing a carboxyl group, hydroxyl group, phosphoric acid group, phosphorous acid group, sulfonic acid group, amide group, quaternary ammonium base and the like. . On the other hand, examples of the radical polymerizable monomer having a group that can be changed into a hydrophilic group include radical polymerizable monomers containing an acid anhydride group, a glycidyl group, a chloro group, and the like. Among these, from the viewpoint of water dispersibility, a carboxyl group is preferable, and a radical polymerizable monomer having a carboxyl group or a group capable of generating a carboxyl group is preferable.

  In order to bring the acid value of the graft reaction product into the above preferred range, it is preferable that a radical polymerizable monomer containing a carboxyl group or having a group capable of generating a carboxyl group is contained. Such monomers include fumaric acid, monoethyl fumarate; maleic acid and its anhydride, monoethyl maleate; itaconic acid and its anhydride, monoester of itaconic acid; acrylic acid, methacrylic acid; and salts thereof (sodium Salt, potassium salt, ammonium salt) and the like. Maleic anhydride is preferable. The said monomer can be copolymerized using 1 type, or 2 or more types.

  The radically polymerizable monomer to be grafted may contain other types of monomers as long as the acid value is within the above-mentioned preferable range. As other types of monomers, monomers that can be used when synthesizing the acrylic polymer described above can be used as they are.

  Examples of the graft polymerization initiator used in the present invention include organic peroxides and organic azo compounds known to those skilled in the art. Examples of the organic peroxide include benzoyl peroxide, t-butyl peroxypivalate, and examples of the organic azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2, 4-dimethyl pareronitrile). The amount of the polymerization initiator used for the graft polymerization is at least 0.2% by mass, preferably 0.5% by mass or more, based on the radical polymerizable monomer.

  In addition to the polymerization initiator, a chain transfer agent for adjusting the chain length of the branched polymer, for example, octyl mercaptan, mercaptoethanol, 3-t-butyl-4-hydroxyanisole may be used as necessary. In this case, it is desirable to add in the range of 0 to 5% by mass with respect to the polymerizable monomer.

  The grafting reaction product is preferably neutralized with a basic compound, and can be easily dispersed in water by neutralization. As the basic compound, a compound that volatilizes at the time of coating film formation is desirable, and ammonia, organic amines, and the like are preferable. Desirable compounds include, for example, triethylamine, N, N-diethylethanolamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine , 3-ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanol An amine etc. can be mentioned.

  The basic compound has a pH value of the aqueous dispersion in the range of 5.0 to 9.0 by at least partial neutralization or complete neutralization according to the carboxyl group content contained in the grafting reaction product. It is desirable to use it as follows. When a basic compound having a boiling point of 100 ° C. or less is used, the amount of residual basic compound in the coating film after drying is reduced, and for example, the resistance to hot water in a harsh environment such as high temperature and high humidity is improved. .

  In the grafting reaction product, the weight average molecular weight of the polymer of the radical polymerizable monomer is preferably 500 to 50,000. It is generally difficult to control the weight average molecular weight of the polymer of the radical polymerizable monomer to be less than 500, the graft efficiency is lowered, and there is a tendency that hydrophilic groups are not sufficiently imparted to the copolymer polyester. In addition, the graft polymer of the radical polymerizable monomer forms a hydrated layer of dispersed particles. To obtain a stable aqueous dispersion with a sufficient thickness of the hydrated layer, graft polymerization of the radical polymerizable monomer is performed. The weight average molecular weight of the product is desirably 500 or more.

  The upper limit of the weight average molecular weight of the graft polymer of the radical polymerizable monomer is preferably 50,000 from the viewpoint of polymerizability in solution polymerization. In order to make the weight average molecular weight of the graft polymer of the radical polymerizable monomer within the range of 500 to 50,000, the initiator amount, the monomer dropping time, the polymerization time, the reaction solvent, the monomer composition, or the chain as necessary. It is preferable to carry out by appropriately combining a transfer agent and a polymerization inhibitor.

  The glass transition temperature of the graft copolymer is not particularly limited, but it is preferably 20 ° C. or higher, more preferably 40 ° C. or higher in consideration of heat resistant water adhesion.

  In the present invention, a reaction product obtained by graft polymerization of a radically polymerizable monomer to a hydrophobic copolymerized polyester has a self-crosslinking property because a hydroxyl group in the polyester and a carboxyl group present in the graft portion react. Moreover, although it does not bridge | crosslink at normal temperature, it carries out intermolecular reaction, such as a hydrogen abstraction reaction by a thermal radical, with the heat at the time of drying at the time of coating film formation, and bridge | crosslinks without a crosslinking agent. As a result, a high degree of heat-resistant water adhesion is exhibited. The degree of crosslinking of the coating film can be evaluated by various methods, and examples thereof include a method of measuring the insoluble fraction in a chloroform solvent or the like that dissolves both the hydrophobic copolymerized polyester and the grafted polymer.

  The insoluble fraction of the coating film obtained by drying at about 80 ° C. and heat-treating at 120 ° C. for 5 minutes is preferably 50% by mass or more, more preferably 70% by mass from the viewpoints of heat resistant water adhesion and blocking resistance. That's it.

  As the self-crosslinking polyester resin aqueous dispersion, for example, a commercially available product such as “Vylonal (registered trademark) AGN702” (manufactured by Toyobo Co., Ltd.) can be used.

  In addition, a grafted polyurethane can be prepared by a method similar to the above.

[Additive for heat resistant water adhesion improving layer (B)]
Various additives such as antioxidants, heat stabilizers, weathering stabilizers, ultraviolet absorbers, and organic easiness can be used in the heat resistant water adhesion improving layer (B) within the range where the effects of the present invention are not impaired. A lubricant, a pigment, a dye, organic or inorganic fine particles, a filler, an antistatic agent, a nucleating agent, and the like may be blended.

  In particular, in the case of adding inorganic particles in the heat resistant water adhesion improving layer (B), for example, the heat resistant water adhesion improving layer (B) is laminated on the surface of the polyester base film (A), and then wound once. Since slipperiness and blocking resistance, such as when taking, improve, it is preferable. In this case, silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate, or the like can be used as the inorganic particles to be added. The average particle size used is preferably 0.005 to 5 μm, more preferably 0.01 to 3 μm, and most preferably 0.05 to 2 μm. Although the usage-amount of an inorganic particle is not specifically limited, It is preferable to mix 0.05-10 mass parts with solid content with respect to 100 mass parts of polymers in a heat-resistant water adhesive improvement layer (B), More preferably, it is 0.00. 1 to 5 parts by mass.

[Method of forming heat resistant water adhesion improving layer (B)]
The heat resistant water adhesion improving layer (B) is an aqueous dispersion of a mixture of at least one polymer selected from the group consisting of polyester, polyurethane and acrylic polymer and a crosslinking agent, or water of a self-crosslinking polymer. Since it is formed from a dispersion, it is the easiest to form by a coating method, and it may be applied to the surface of the polyester base film (A). Suitable is a method of applying to an unstretched film of the polyester base film (A) and then stretching in at least one direction, a method of applying after longitudinal stretching, a method of applying to the film surface after the orientation treatment, etc. A method is also possible. In particular, when the polyester base film (A) is produced, it is applied before the crystal orientation of the film is completed, and then stretched in at least one direction, and then the so-called in-line coating is completed to complete the crystal orientation of the polyester film. Since the method can easily form a thin film, the effects of the present invention can be more remarkably exhibited.

  For example, when the coating liquid is applied to the unstretched film of the polyester base film (A), various coating methods such as reverse coating method, gravure coating method, rod coating method, bar coating method, Meyer bar A coating method, a die coating method, a spray coating method, or the like can be used.

  You may provide a heat-resistant water adhesive improvement layer (B) on both surfaces of a polyester-type base film (A).

[Adhesive layer (C)]
In the protective film for display screen of the present invention, it is the adhesive layer (C) that contacts the release layer (D) described later. This adhesive layer (C) contains a crosslinked silicone compound having a polydimethylsiloxane skeleton as a main component (70% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass).

  The crosslinked silicone compound having the polydimethylsiloxane skeleton is preferably a crosslinked silicone compound having a number average molecular weight (Mn) of 50,000 to 500,000. The uncrosslinked Mn is more preferably 80,000 to 400,000, and more preferably 100,000 to 350,000.

  By using an uncrosslinked product of the silicone compound, solubility in a solvent and fluidity can be ensured, and formation of the adhesive layer (C) is facilitated. Moreover, since Mn of 50,000 or more of an uncrosslinked body improves crosslinkability, it is suitable. When the Mn of the uncrosslinked product is 500,000 or less, deterioration in operability during production such as the viscosity of the coating solution becoming too high can be suppressed.

  As an uncrosslinked silicone compound satisfying the above contents, for example, a commercially available silicone oil can be used. When silicone oil is used, non-reactive dimethyl silicone oil is preferably used among straight silicone oils. Thereby, the silicone compound after crosslinking has a polydimethylsiloxane skeleton. The methyl phenyl type silicone oil has poor crosslinkability, and the reactive methyl hydrogen type silicone oil has poor storage stability, which may adversely affect the quality and operability. If it is less than (more preferably less than 5 mass%), you may mix | blend and use the silicone compound which does not have polydimethylsiloxane frame | skeleton, such as a methylphenyl type, a methyl hydrogen type, or various modified types.

  The uncrosslinked silicone compound may contain a polyalkylalkenylsiloxane skeleton silicone compound as long as it is less than 10% by mass. Most preferably, it consists only of a polydimethylsiloxane skeleton silicone compound that does not contain a polyalkylalkenylsiloxane skeleton silicone compound.

  The pressure-sensitive adhesive layer (C) in the present invention may contain a reinforcing agent such as silica as long as it does not interfere with the effects of the present invention, but it is particularly preferred that no reinforcing agent is contained.

  By using the above-mentioned uncrosslinked silicone compound, as described above, it is superior in terms of quality, quality stability, operability during production, etc., as compared with the case where a conventionally known millable type silicone compound is used as a raw material. The effect is manifested.

  The pressure-sensitive adhesive layer (C) includes an adhesion improver for increasing the adhesive strength between the pressure-sensitive adhesive layer (C) and the heat resistant water adhesion improving layer (B) and making it difficult to peel off the pressure-sensitive adhesive layer (C). It may be. As the adhesion improver, it is preferable to use a compound containing a reactive group active against radical reaction. Examples of this compound include (meth) acrylic acid derivatives and allyl derivatives. Among them, derivatives having 2 or more, particularly 3 or more unsaturated bonds are preferred. These compounds are widely used as rubber co-crosslinking agents, and examples include esters of polyhydric alcohol and (meth) acrylic acid, allyl esters of polycarboxylic acid, triallyl isocyanurate, triallyl cyanurate, and the like. .

  The ester of the polyhydric alcohol and (meth) acrylic acid is an ester compound obtained by esterifying two or more alcoholic hydroxyl groups of a polyhydric alcohol having two or more alcoholic hydroxyl groups with (meth) acrylic acid. Specifically, for example, ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Neopentyl glycol di (meth) acrylate, 2,2'-bis [4- (meth) acryloxydiethoxyphenyl] propane, glycerol di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, tetramethylolmethane di (meth) acrylate, tetramethylolmethanetri (meth) acrylate, Tiger methylol tetra (meth) acrylate, dimer diol di (meth) acrylate and the like, particularly compounds containing three or more (meth) acryloyl group is preferred. In addition, although said compound illustrated each single ester compound of acrylic acid and methacrylic acid, the form of mixed ester of acrylic acid and methacrylic acid may be sufficient.

  Examples of the allyl ester of polyvalent carboxylic acid include phthalic acid diarylate, trimellitic acid diarylate, and pyromellitic acid tetraarylate.

  Any one of the above-mentioned adhesiveness improvers may be used alone, or two or more thereof may be used in combination. Further, the adhesion improver used in the present invention is not limited to the above exemplary compounds.

  0.2-20 mass parts is preferable with respect to 100 mass parts of silicone compound components, and, as for the compounding quantity of the said adhesive improvement agent, 0.5-10 mass parts is more preferable. By making the compounding amount of the adhesion improver 0.2 parts by mass or more, the effect of improving the hot water adhesion of the pressure-sensitive adhesive layer (C) is further increased. On the other hand, when the compounding amount of the adhesion improver exceeds 20 parts by mass, the effect of improving the hot water adhesiveness not only reaches saturation, but conversely, this effect may be deteriorated.

  The lower limit of the thickness of the adhesive layer (C) is preferably 3 μm, more preferably 5 μm, and even more preferably 8 μm from the viewpoint of adhesive strength. On the other hand, the upper limit of the thickness of the pressure-sensitive adhesive layer (C) may be determined within a range in which the pressure-sensitive adhesive force can be stably maintained from the viewpoint of economy. For example, 100 μm is preferable, 80 μm is more preferable, and 50 μm is further preferable.

  In the present invention, the method for forming the above-mentioned pressure-sensitive adhesive layer (C) is not limited, but the above-mentioned uncrosslinked silicone compound is dissolved or dispersed in a solvent, and an adhesion improver is added as necessary to apply the coating solution. It is a preferred embodiment that is prepared by applying a coating method, followed by crosslinking treatment.

  For example, uncrosslinked silicone oil dissolves well in aromatic hydrocarbons such as toluene. Therefore, it is preferable to dissolve in these solvents and apply by a coating method. When an uncrosslinked silicone oil is used, a compound plasticizing step by kneading or the like necessary for dissolving a conventional millable type silicone rubber compound in a solvent becomes unnecessary. In addition, the obtained coating solution has good storage stability, and does not cause a thickening phenomenon such as gelation, which is often seen when preparing a solution of a silicone rubber compound. Furthermore, since the production | generation of the foreign material by the silicone rubber compound not melt | dissolving which may generate | occur | produce in the solutionization of a silicone rubber compound is suppressed, there exists a merit that a coating liquid with high clarity is obtained.

  For example, the pressure-sensitive adhesive layer (C) is formed by applying a coating liquid containing the above silicone oil or the like to the surface of the heat resistant water adhesion improving layer (B) formed on the surface of the polyester base film (A), or the polyester film ( It can form by apply | coating to the surface of the mold release layer (D) formed in the surface of E), and laminating | stacking another layer, or not laminating | stacking.

  The crosslinking method of the silicone compound may be, for example, thermal crosslinking, or may be crosslinking with high energy active rays such as electron beams and γ rays. It is considered that when an active ray is irradiated on a silicone compound, hydrogen is extracted from the methyl group of polydimethylsiloxane, and a crosslinking reaction occurs between adjacent silicone compounds from which hydrogen is extracted from the methyl group. Therefore, in the crosslinking method using actinic radiation, it is not necessary to add an additive such as a peroxide for radical generation or a crosslinking catalyst to the silicone compound. For this reason, the contamination of the adherend due to the residue of these additives is suppressed, and it is not necessary to consider the pot life after blending the crosslinking catalyst, etc., so that the crosslinking is completed efficiently in a short time. There is an advantage that becomes higher.

  Among the actinic rays, the electron beam cross-linking method is preferable because of the availability of an irradiation device (EB irradiation device). As an electron beam irradiation amount by EB irradiation apparatus, the range of 5-50 Mrad is preferable. By setting the electron beam irradiation amount to 5 Mrad or more, the crosslinking reaction of the silicone compound can be promoted, and the adhesive residue on the adherend can be reduced and the repairability can be improved when re-peeling. On the other hand, by setting the electron beam irradiation amount to 50 Mrad or less, it is possible to suppress a decrease in adhesiveness due to excessive progress of the crosslinking reaction.

  The lower limit of the adhesive strength of the adhesive layer (C) is 0.01 N / 20 mm (against a 180-degree peel test, a pulling speed of 300 mm / min) from the viewpoint of reliability when used when attached to a display screen. Is more preferable, and 0.05 N / 20 mm is more preferable. On the other hand, the upper limit of the adhesive strength of the adhesive layer (C) is preferably 1.0 N / 20 mm, more preferably 0.5 N / 20 mm from the viewpoint of improving removability and ensuring good repairability. is there. Moreover, it is preferable from the point of repair property that the adhesion layer does not remain on the glass surface when evaluated by the above evaluation method, that is, there is no adhesive residue.

[Release layer (D)]
The release layer (D) in the protective film for display screen of the present invention is preferably made of a composition containing a binder resin, a polymer wax component and an antistatic agent. The release layer (D) is a set with the polyester film (E) and becomes a separate film (DE) of the adhesive layer (C). The binder resin is preferably one or more polymers selected from the group consisting of polyesters, polyurethanes and acrylic polymers. These polymers may be used alone, or two or three different types may be used. May be used in combination.

  As the polyester, polyurethane, and acrylic polymer, the same polymers as those described later can be used as the constituent polymer of the heat resistant water adhesion improving layer (B). Although the binder resin has a low necessity for crosslinking, a crosslinking agent may be used in the same manner as in the heat resistant water adhesion improving layer (B), or a self-crosslinking polymer may be used.

  As the polymer wax component used in the present invention, conventionally known materials can be used. For example, wax emulsions such as polyethylene, polypropylene, acrylic, and fatty acid are shown, but a polymer wax agent that is particularly hard and does not have a sticky feeling and has excellent thermal decomposition stability is effective in improving peelability. Further, it is preferable because the transfer of wax to the opposite surface can be suppressed during film winding. Moreover, the preferable number average molecular weights of these wax agents are 1000-10000, More preferably, it is the range of 1500-6000.

  The polymer wax component is preferably contained in a solid content of 2 to 10% by mass when the total with the binder resin is 100% by mass. More preferably 3 to 8% by mass is contained. By making the addition amount of the polymer wax component 2% by mass or more, the peelability from the adhesive layer (C) after the crosslinking treatment can be improved, and the slipperiness of the separate film (DE) can be improved. . On the other hand, by setting the addition amount of the polymer wax component to 10% by mass or less, it is possible to maintain the peeling force and suppress the occurrence of the channeling phenomenon in the manufacturing process of the display screen protective film. Furthermore, since the migration of the polymer wax component from the release layer (D) can be suppressed, the surface of the pressure-sensitive adhesive layer (C) after the crosslinking treatment is less contaminated.

  The antistatic agent used in the release layer (D) is not particularly limited as long as it can be mixed with the binder resin or is compatible with the binder resin. For example, any of anionic, cationic, nonionic, amphoteric surfactants, polymeric surfactants, and the like can be used. Preferably, a polymer type antistatic agent with little bleed out to the laminated surface is preferred.

  As the polymer type antistatic agent, any of anionic, cationic and nonionic types can be used, and among them, anionic and nonionic type polymeric surfactants are preferable.

  As the anionic polymer type surfactant, for example, a polar polymer having at least one polar group selected from a sulfonic acid group, a carboxyl group, and a sulfate group, or a salt thereof is preferable. The polar group needs 5 mol% or more per polymer molecule. These polar polymers having electrical conductivity may contain hydroxyl groups, amino groups, epoxy groups, aziridine groups, active methylene groups, sulfinic acid groups, aldehyde groups, and vinyl sulfone groups as polar groups. Among these, a surfactant containing styrene sulfonic acid or a salt thereof as a repeating unit is preferable.

  Examples of such a surfactant include polystyrene sulfonic acid or a salt thereof. Examples of the salt include ammonium salt, lithium salt, and sodium salt. Polystyrene sulfonic acid or a salt thereof is, for example, commercially available from Nippon SC under the trade name VERSA-TL (registered trademark) and various types of unneutralized salts having different molecular weights. Further, as a surfactant containing styrene sulfonic acid or a salt thereof as a repeating unit, a styrene sulfonic acid-maleic acid copolymer can be used and is commercially available from Nippon SC.

  On the other hand, nonionic high molecular surfactants include aniline or derivatives thereof, pyrrole or derivatives thereof, isothianaphthene or derivatives thereof, acetylene or derivatives thereof, thiophene or derivatives thereof, and the like. Is preferred. Among them, a π-electron conjugated conductive polymer containing thiophene or a derivative thereof as a structural unit is preferable because it is less colored. The π-electron conjugated conductive polymer may be a homopolymer containing only one type of structural unit as a repeating unit or a copolymer containing two or more types of structural units as a repeating unit.

  Examples of the conductive polymer containing thiophene or a derivative thereof as a constitutional unit include, for example, “BYTRON (registered trademark) P” series manufactured by Starck Vitech, and “Denatron (registered trademark) P-502RG” manufactured by Nagase ChemteX. "Denatron (registered trademark) P-502S", Conisole F202, F205, F210, P810 (above, trade name) manufactured by Inscontec, CPS-AS-X03 (trade name) manufactured by Shin-Etsu Polymer, etc. are commercially available. .

  The blending amount of the antistatic agent in the release layer (D) cannot be determined uniquely because the preferred range varies depending on the type of the binder resin and the type of the antistatic agent, and the adhesive of the release layer (D). What is necessary is just to adjust so that the peeling strength from a layer (C) may become the range mentioned later.

  For example, when an anionic surfactant is used as the antistatic agent, the blending amount of the antistatic agent is such that the peel strength of the release layer (D) from the adhesive layer (C) is within the above range. When the total amount with the binder resin is 100% by mass, the solid content is preferably 2 to 10% by mass, and more preferably 3 to 8% by mass. By making the blending amount of the anionic surfactant 2% by mass or more, the peelability from the adhesive layer (C) after the crosslinking treatment is improved and the antistatic property of the separate film (DE) is also improved. . On the other hand, by setting the blending amount of the antistatic agent to 10% by mass or less, it is possible to maintain the peeling force and suppress the occurrence of the channeling phenomenon in the manufacturing process of the display screen protective film. Furthermore, since the migration of the polymer wax component from the release layer (D) can be suppressed, the surface of the pressure-sensitive adhesive layer (C) after the crosslinking treatment is hardly contaminated.

  In order to form the release layer (D) having the above structure on the polyester film (E), other additives such as a binder resin, a polymer wax component, an antistatic agent, and a surface roughening substance as required The resin composition may be prepared by mixing a predetermined amount in advance and coated. The resin composition may contain a surfactant for improving coatability, an ultraviolet ray inhibitor, an antioxidant, and the like. The coating method may be applied using a normal coating apparatus such as a gravure coater, reverse roll coater, reverse kiss coater, air knife coater, bar coater, etc., and the method is not limited to these. As in the case of the heat resistant water adhesion improving layer (B) described above, when obtaining a separate film (DE), a resin composition is applied to one side of the uniaxially stretched film (E), and further Examples thereof include a so-called in-line coating method in which stretching is performed in a direction perpendicular to uniaxial stretching, a so-called offline coating method in which coating is performed after biaxial stretching.

  The thickness of the release layer (D) is preferably 0.03 to 1 μm and more preferably 0.05 to 0.5 μm in a dry state in order to make the peeling force within an appropriate range.

  Generally, a silicone compound is used as the release layer. For example, when the release layer (D) is made of a cured product of a general-purpose curable silicone compound, it has a high affinity with the adhesive layer (C), so that the silicone compound in the adhesive layer (C) is crosslinked. At this time, the pressure-sensitive adhesive layer (C) and the release layer (D) may undergo a crosslinking reaction, and the peelability may be reduced. In order to obtain stable peelability, the release layer (D) preferably has the above composition. That is, it is preferable to form using a release agent that does not substantially contain a silicone compound. Here, “the release layer (D) is made of a non-silicone compound” means that the release layer (D) is formed of a compound (or composition) containing 10% by mass or less of a silicone compound. This means that the more preferable amount of the silicone compound is 5% by mass or less, and the most preferable amount of the silicone compound is 0% by mass.

  The release layer (D) may be made of a metal or an inorganic thin film. However, from the viewpoint of peeling stability and cost, the release layer (D) is made of the above composition. Is preferred.

[Peel strength between adhesive layer (C) and release layer (D)]
In the display screen protective film of the present invention, it is preferable that the peel strength between the adhesive layer (C) and the release layer (D) is 0.03 to 1.0 N / 20 mm. When the peel strength is 0.03 N / 20 mm or more, the film exhibits good peelability and can suppress the separation film (DE) from being lifted when the display screen protective film is wound up. The quality of the film can be kept high. On the other hand, if it is 1.0 N / 20 mm or less, the peelability of a separate film (DE) is favorable. When the peel strength is greater than 1.0 N / 20 mm, cohesive failure of the adhesive layer (C) and cutting of the separate film (DE) may occur, and the peelability may deteriorate. In order to control the peel strength within the above range, it is preferable to provide the release layer (D) having the above configuration on the surface of the polyester film (E). The peel strength is measured as follows.

  A protective film sample for a display screen having a length of about 200 mm and a width of 20 mm is peeled off slightly at the interface between the adhesive layer (C) and the release layer (D) to expose each of the adhesive layer (C) and the release layer (D). Let Next, the laminate of the polyester-based substrate film (A) to the adhesive layer (C) is held with one chuck, and the separate film (D) composed of the release layer (D) and the polyester film (E) with the other chuck ( DE). Then, the T-type peel strength is measured by the method described in JIS K6854-3. As a tensile tester, a trade name “Autograph” (manufactured by Shimadzu Corporation) can be used, and a T-type peel test is performed under conditions of a distance between chucks of 50 mm, a temperature of 23 ° C., and a tensile speed of 200 mm / min. During peeling, the end of the film is lifted with a stick so that the T-shape is maintained. The maximum strength at the time of T-type peeling is defined as peeling strength.

  Hereinafter, in the present invention, the above characteristic may be simply referred to as peelability.

[Adhesiveness]
In the present invention, the pressure-sensitive adhesive layer (C), the heat resistant water adhesion improving layer (B), the heat resistant water adhesion improving layer (B), and the polyester base film (A) are firmly bonded. preferable. Here, the term “adhering firmly” specifically refers to inserting a cutter knife between the adhesive layer (C) and the polyester base film (A) and applying force with a finger. This means that when peeling (exposing the interface) is carried out, the two are firmly bonded and the interfacial cannot be formed. In the present invention, the heat resistant water adhesion improving layer (B) exists between the pressure-sensitive adhesive layer (C) and the polyester base film (A). The true interface of is not clear. In short, it is preferable that the pressure-sensitive adhesive layer (C) and the polyester-based substrate film (A) are firmly bonded and the interface cannot be formed. Hereinafter, in the present invention, this characteristic may be simply referred to as adhesiveness.

  Moreover, it is more preferable that the protective film for display screens of the present invention is excellent in the adhesive hot water resistance. Hereinafter, this characteristic is sometimes referred to as heat resistant water adhesion. The hot water adhesion is measured as follows.

[Heat resistant water adhesion]
The protective film for display screen is cut into 50 mm × 50 mm, and the separate film (DE) is peeled from the protective film for screen. The sample is submerged in a 500 cc cylindrical glass container with a lid containing 400 cc of distilled water so that the adhesive layer (C) is on the lower side, and the entire sample is immersed in water. Put the lid on. In the case where the sample is not immersed in water by its own weight, for example, a polyester film having a size of 60 mm × 60 mm and a thickness of 188 μm may be placed on the sample and weighted. The size and material of the weight are not particularly limited, and the entire sample may be immersed in water. The container containing the sample is placed in a gear oven set at 80 ° C. and allowed to stand for 24 hours. After the heat treatment, the container is taken out from the oven, the sample is quickly taken out, the surface of the adhesive layer (C) is rubbed 10 times with the finger pad from the end of the sample toward the center of the sample, and the adhesive layer (C) It is evaluated whether or not the polyester base film (A) is peeled off, and the case where the pressure-sensitive adhesive layer (C) is not peeled is indicated by ◯, and the case where the pressure-sensitive adhesive layer (C) is peeled is indicated by x. In this heat resistant water adhesion, by selecting a heat resistant water adhesion improving layer (B) that does not peel off the pressure sensitive adhesive layer (C), for example, when used as a protective film for display screens of various display devices, Since the water-resistant adhesion durability between the layer (C) and the polyester base film (A) can be improved, the reliability as a protective film for a display screen is improved.

[Optical characteristics of protective film for display screen]
The display screen protective film of the present invention has a total light transmittance of 85% or more and a haze of 10% in a state where a separate film (DE) is peeled from the film in applications requiring high transmittance. The following is preferable. More preferably, the total light transmittance is 90% or more and the haze is 5% or less. Furthermore, it is preferable that the total light transmittance and haze are within the above-described preferred range even after storage at 65 ° C. and 85 RH% for 200 hours.

  The display screen protective film of the present invention can be suitably used as a protective film for a display device screen of an optical member by having the above properties, but is not limited to this application.

[Method for producing protective film for display screen]
The display screen protective film is not particularly limited, but is preferably manufactured by any of the following methods. This is because the above-described characteristics can be stably expressed and the economy is excellent. In each production method, each process is basically performed in the order described. A step not described may be performed between a certain step and the next step.

The first method is as follows.
A step of laminating the heat resistant water adhesion improving layer (B) on one side of the polyester base film (A) to form a laminate (1);
A step of laminating a layer containing an uncrosslinked product of a silicone compound having a polydimethylsiloxane skeleton on the surface of the heat resistant water adhesion improving layer (B) of the laminate (1) to form a laminate (2);
A step of laminating the release layer (D) on one side of the polyester film (E) to form a laminate (3);
The laminates (2) and (3) are formed so that the release layer (D) of the laminate (3) is in contact with the surface of the layer (2) containing an uncrosslinked silicone compound having a polydimethylsiloxane skeleton. ) To form a laminate (4),
A step of crosslinking a non-crosslinked body of the silicone compound having a polydimethylsiloxane skeleton of the laminate (4) to form a laminate (4 ′) having an adhesive layer (C);
It is a manufacturing method containing.

The second method is as follows.
Forming the laminate (3);
A step of laminating a layer containing an uncrosslinked product of a silicone compound having a polydimethylsiloxane skeleton on the surface of the release layer (D) of the laminate (3) to form a laminate (5);
Forming the laminate (1);
Laminate (5) so that the layer containing the uncrosslinked product of the silicone compound having a polydimethylsiloxane skeleton in the laminate (5) is in contact with the surface of the heat resistant water adhesion improving layer (B) of the laminate (1). And laminating the laminate (1) to form the laminate (4),
Forming the laminate (4 ′);
It is a manufacturing method containing.

[How to use display screen protection film]
The protective film for a display screen of the present invention is a display screen when using various image display devices such as a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence panel (ELP), a touch panel, and a CRT (cathode ray tube) display. In addition to protection of the above, it is also suitably used for protection of a display screen in the manufacturing process of the device.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, but may be implemented with appropriate modifications within a scope that can meet the gist of the present invention. These are all included in the technical scope of the present invention. The measurement / evaluation methods employed in the examples are as follows. In the examples, “parts” means “parts by mass”, and “%” means “% by mass” unless otherwise specified.

1. Peelability A protective film sample for a display screen having a length of about 200 mm and a width of 20 mm is peeled off slightly at the interface between the adhesive layer (C) and the release layer (D), and each of the adhesive layer (C) and the release layer (D) Was exposed. Next, the laminate of the polyester-based substrate film (A) to the adhesive layer (C) is held with one chuck, and the separate film (D) composed of the release layer (D) and the polyester film (E) with the other chuck ( DE) was gripped. And T-type peeling strength was measured by the method as described in JIS K6854-3. The tensile tester used was a trade name “Autograph” (manufactured by Shimadzu Corporation), and a T-type peel test was performed under conditions of a distance between chucks of 50 mm, a temperature of 23 ° C., and a tensile speed of 200 mm / min. During peeling, the end of the film was lifted with a bar so that the T-shape was maintained. The maximum strength at the time of T-type peeling was defined as the peeling strength. The release layer (D) and the pressure-sensitive adhesive layer (C) are firmly adhered to each other, or the pressure-sensitive adhesive layer (C) is agglomerated and broken or the separation film (DE) is cut off. When (C) did not peel, it was not measured as difficult to peel. In this case, it indicates that the release layer (D) does not function as a release layer. Note that “difficult to peel” indicates that the peel strength is greater than 1.0 N / 20 mm.

2. Adhesiveness A cutter knife was inserted between the pressure-sensitive adhesive layer (C) and the polyester base film (A), and peeling was performed by applying force with a finger (exposing the interface). The case where the peel strength was strong and the interface could not be evaluated was evaluated as ◯, and the case where the interface could be aligned was evaluated as ×.

3. Heat-resistant water adhesion The double-sided PSA sheet was cut into 50 mm x 50 mm, and the separate film (DE) composed of the polyester film (E) and the release layer (D) was peeled off. The sample is submerged in a 500 cc cylindrical glass container with a lid containing 400 cc of distilled water so that the adhesive layer (C) is on the lower side, and the entire sample is immersed in water. Covered. When the sample was not immersed in water by its own weight alone, for example, a polyester film having a size of 60 mm × 60 mm and a thickness of 188 μm was placed on the sample to form a weight.

  The container containing the sample was placed in a gear oven set at 80 ° C. and allowed to stand for 24 hours. After the heat treatment, take out the container from the oven, quickly take out the sample, rub the adhesive layer (C) surface 10 times from the end of the sample toward the center with finger pad, and the adhesive layer (C) is polyester It evaluated whether it peeled from the type | system | group base film (A) side, and what evaluated the thing which the adhesion layer (C) does not peel as (circle) and the adhesion layer (C) peeled as x.

4). Adhesive strength The adhesive strength of the adhesive layer (C) to the glass was measured by a 180-degree peeling method according to JIS Z0237. As the glass, heat resistant glass having a thickness of 3 mm and a width of 30 mm was used. The sample had a width of 20 mm, and was adhered to the glass by reciprocating twice at a speed of about 29 mm / second using a 2 kg roller. The tensile speed was 300 mm / min, a tensile test was performed in an atmosphere at 23 ° C., and the maximum tensile strength was the adhesive strength (N / 20 mm).

5. Total light transmittance and haze The total light transmittance was measured according to JIS K7361-1, and the haze was measured according to JIS K7136 using a Nippon Denshoku Industries Co., Ltd. haze measuring instrument “NDH-2000”. This measurement was performed with the separate film (DE) peeled off.

6). Clarity of the coating solution 100cc of the coating solution for forming the adhesive layer (C) is filtered through a wire mesh of 200mm (wire diameter 0.04mm) of 40mmφ, and the presence or absence of insoluble matter is confirmed with the naked eye. The case was marked with ○ and the case with insoluble matter was marked with ×.

7). Solution stability of the coating solution The coating solution for forming the adhesive layer (C) was evaluated by the change in viscosity of the solution when stored in a sealed state at room temperature (23 ° C) for 90 days to determine solution stability. The case where the change in viscosity of the solution was within ± 20% was marked as ◯, and the case where the change in viscosity of the solution exceeded ± 20% was marked as x. The viscosity was measured with a B-type viscometer.

Example 1
(1) Preparation of coating solution for forming heat resistant water adhesion improving layer (B) [Preparation of water dispersible copolyester resin]
A copolyester was synthesized in a batchwise manner using one pressure esterification reaction vessel with a distillation column and two polycondensation reaction vessels with a vacuum generator.

  First, 229 kg of terephthalic acid, 222 kg of isophthalic acid, 191 kg of 5-sodiumsulfoisophthalic acid di (hydroxyethyl) ester (ethylene glycol solution containing 34%) and 213 kg of neopentyl glycol melted at 140 ° C. in a nitrogen atmosphere in an esterification reaction tank Furthermore, 87 kg of a mixed solution of ethylene glycol and neopentyl glycol (mass ratio 45:55) recovered and refined (mass ratio 45:55) and 39 kg of an antimony trioxide ethylene glycol solution (antimony trioxide concentration 1.3%) were added while stirring. (0.05 mol% as antimony trioxide with respect to the acid component) and then pressurizing with nitrogen, raising the temperature of the reaction vessel with a heat medium and controlling the top temperature to 150 ° C., glycol in the reaction vessel Under a pressure of 0.3 MPa (gauge pressure). ℃ performed 130 minutes esterification reaction to obtain an oligomer of copolyester.

  Next, the oligomer was transferred to the first polycondensation reaction tank, and while stirring, the pressure was reduced to 40 kPa at a pressure reduction rate of 5 kPa / min, and then to 0.3 kPa at a pressure reduction rate of 0.8 kPa / min. And a prepolymer of copolyester was obtained. Thereafter, the prepolymer was transferred to a second polycondensation reaction tank in which a spiral stirring blade was rotated under a vacuum of 0.13 kPa, and subjected to late condensation at a temperature of 265 ° C. for 120 minutes to obtain a reduced viscosity of 0.41. It was set as the copolymer ester polymer of this. Nitrogen was introduced into the second polycondensation reaction tank, and the copolymerized ester polymer was taken out as a 7 mm thick sheet with a gear pump, and crushed with a sheet cutter while cooling with water to obtain a crushed copolymerized polyester.

[Preparation of coating solution]
100 parts of the crushed material was dispersed in water by a conventional method. With respect to 100 parts of the solid content of this aqueous dispersion, 5 parts of methylol melamine resin “Cymel (registered trademark) 303” (manufactured by Mitsui Cytec Co., Ltd.) is used as the catalyst, and “Catalyst 600” (Mitsui Cytec Co., Ltd.) as the catalyst. Product) was added and stirred well to obtain a coating solution (B-1).

(2) Production of polyester base film (A) and lamination of heat resistant water adhesion improving layer (B) Amorphous silica (Silycia; manufactured by Fuji Silysia) with an average particle diameter (SEM method) of 1.5 μm is 0. 0.04% polyethylene terephthalate pellets (intrinsic viscosity 0.65 dl / g) pellets were sufficiently dried in vacuum, then supplied to an extruder heated to 280 ° C., extruded into a sheet from a T-shaped die, and electrostatically applied Using a casting method, it was wound around a mirror casting drum having a surface temperature of 30 ° C. and cooled and solidified. The unstretched film was stretched 3.5 times in the longitudinal direction while passing through a heating roll group at 95 ° C. to obtain a uniaxially stretched film. Both surfaces of this film were subjected to corona discharge treatment, and the coating liquid (B-1) was applied to both treatment surfaces. The uniaxially stretched film was guided to a preheating zone while being held with a clip, dried at 110 ° C., and continuously stretched 3.5 times in the width direction in a heating zone at 125 ° C. Further, heat treatment was performed for 6 seconds at 225 ° C. while relaxing 6% in the width direction. A laminate (i) having a thickness of 100 μm was obtained in which a 0.08 μm-thick crosslinked heat-resistant water adhesion improving layer (B1) was laminated on both sides of the biaxially stretched polyethylene terephthalate base film (A1). .

(3) Lamination of hard coat layer 5 parts by mass of methyl ethyl ketone is added to 5 parts by mass of hard coat agent (manufactured by Dainichi Seika, Seika Beam EXF01 (B); solid content 100% by mass) on one side of the above laminate (i). The solution was applied using a # 8 wire bar and dried at 70 ° C. for 1 minute to remove the solvent. Next, while the laminate (i) coated with the hard coat layer was run at a feeding speed of 5 m / min, ultraviolet light was applied to the hard coat layer surface under the conditions of irradiation energy of 200 mJ / cm ² and irradiation distance of 15 cm using a high pressure mercury lamp. Irradiated to obtain a hard coat laminated film (ii) having a hard coat layer having a thickness of 3 μm.

(4) Lamination of antireflection layer The surface of the hard coat layer of the hard coat laminate film (ii) is coated with a high refractive index coating agent obtained by the following method, dried at 150 ° C. for 2 minutes, and a film thickness of 0.1 μm. The high refractive index layer was formed. On this high refractive index layer, the low refractive index coating agent obtained by the following method was applied and dried at 150 ° C. for 2 minutes to form a low refractive index layer having a thickness of 0.1 μm. The obtained laminated film was irradiated with ultraviolet rays at 1000 mJ / cm ² to completely cure the antireflection layer and the hard coat layer, thereby obtaining a laminate (iii) having an antireflection layer.

(4-1) Preparation of High Refractive Index Coating Agent 80 parts of methyl methacrylate, 20 parts of methacrylic acid, 1 part of azoisobutyronitrile, and 200 parts of isopropyl alcohol are charged into a reaction vessel, and a nitrogen atmosphere is maintained at 80 ° C. for 7 hours. By reacting, an isopropyl alcohol solution of a polymer having a weight average molecular weight of 30,000 was obtained.

  The obtained polymer solution was further diluted with isopropyl alcohol to a solid content of 5% to obtain an acrylic resin solution.

The obtained acrylic resin solution was mixed according to the following composition to obtain a high refractive index coating agent.
Acrylic resin solution: 5 parts Bisphenol A diglycidyl ether: 0.25 parts Titanium oxide particles having an average particle diameter of 20 nm: 0.5 parts Triphenylphosphine: 0.05 parts Isopropyl alcohol: 14.25 parts

(4-2) Preparation of low refractive index coating agent 45 parts of 2,2,2-trifluoroethyl acrylate, 45 parts of perfluorooctylethyl acrylate, 10 parts of acrylic acid, 1.5 parts of azoisobutyronitrile, methyl ethyl ketone 200 Part was charged into a reaction vessel and reacted at 80 ° C. for 7 hours under a nitrogen atmosphere to obtain a methyl ethyl ketone solution of a polymer having a weight average molecular weight of 20,000.

  The obtained polymer solution was diluted with methyl ethyl ketone to a solid content of 5% to obtain a fluoropolymer solution.

The obtained fluoropolymer solution was mixed according to the following composition to obtain a low refractive index coating agent.
Fluoropolymer solution: 44 parts 1,10-bis (2,3-epoxypropoxy) -2,2,3,3,4,4,5,5,6,6,7,7,8,8,9, 9-hexadecafluorodecane (fluorite FE-16: manufactured by Kyoeisha Chemical Co., Ltd.): 1 part Triphenylphosphine: 0.1 part Methyl ethyl ketone: 19 parts

(5) Preparation of Release Layer (D) Forming Coating Liquid “Vylonal (registered trademark) MD-1200” (manufactured by Toyobo Co., Ltd.), which is a water-dispersible copolyester resin, is used as a binder resin. Polyethylene emulsion wax agent (manufactured by Riken Vitamin Co., Ltd.) as an anionic antistatic agent (sodium dodecyl diphenyl oxide disulfonate; trade name TB702; manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) as an antistatic agent. Styrene-benzoguanamine-based spherical organic particles “Eposter (registered trademark) MS” (manufactured by Nippon Shokubai Co., Ltd.) having a particle size of 2 μm and colloidal silica “Snowtex (registered trademark) XL” (Nissan Chemical Industries) having an average particle size of 0.05 μm Were used respectively.

  Using a homogenizer, the organic spherical fine particles of the surface roughening material are sufficiently dispersed in a mixed solution of water and isopropyl alcohol (mass ratio 80/20), and then the binder with respect to the total mass of the coating solution. The coating solution is thoroughly mixed so that the resin is 2.5%, the polymer wax component is 0.13%, the antistatic agent is 0.13%, the organic spherical fine particles are 0.025%, and the colloidal silica is 0.3%. (D-1) was prepared.

(6) Manufacture of polyester film (E) and lamination of release layer (D) Pellets of polyethylene terephthalate (intrinsic viscosity 0.65 dl / g) are sufficiently vacuum dried and then supplied to an extruder heated to 280 ° C. Then, the sheet was extruded from a T-shaped base into a sheet shape, wound around a mirror casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method, and cooled and solidified. The unstretched film was stretched 3.5 times in the longitudinal direction while passing through a heating roll group at 95 ° C. to obtain a uniaxially stretched film. The coating liquid (D-1) prepared by the above method was applied to both surfaces of this uniaxially oriented film. The coated uniaxially stretched film was guided to a preheating zone while being held with a clip, dried at 110 ° C., and continuously stretched 3.5 times in the width direction in a heating zone at 125 ° C. Further, heat treatment was performed for 6 seconds at 225 ° C. while relaxing 6% in the width direction. A laminated body (iv) (corresponding to a separate film DE-1) having a thickness of 50 μm in which a release layer (D1) having a thickness of 0.15 μm was laminated on both sides of the polyester film (E1) was obtained.

(7) Lamination of pressure-sensitive adhesive layer (C) Non-reactive comprising a non-crosslinked polydimethylsiloxane skeleton having substantially no reinforcing agent such as silica and having a number average molecular weight of 150,000 (measured by GPC method, converted to polystyrene) The silicone compound (KF-96H-500,000 cs; manufactured by Shin-Etsu Chemical Co., Ltd.) was weighed so that the mass ratio to toluene was 23%, and was put together with toluene into a stirrer equipped with a vacuum defoaming device. The mixture was stirred at room temperature for 15 hours and dissolved in toluene. To the obtained solution, trimethylolpropane trimethacrylate was added to 100 parts of the silicone compound so as to be 2 parts, and after stirring uniformly, the vacuum deaerator was driven and the gauge pressure was -750 mmHg. Stir under vacuum for another 20 minutes and degas. Next, the defoamed silicone compound solution is supplied to a roll coater, and the silicone compound solution is applied to the surface of the heat resistant water adhesion improving layer (B) of the laminate (iii) so that the thickness after drying is 25 μm. Subsequently, it was introduced into an oven and dried at 80 ° C. A laminate (v) in which an uncrosslinked adhesive layer (C-1) was formed on the surface of the laminate (iii) was obtained.

The laminate (iv) was stacked on the surface of the uncrosslinked adhesive layer (C-1) of the laminate (v) while being pressed with a pressure roller (pressure 30 N / cm ² ) and continuously laminated. The resulting laminate (vi) was further continuously introduced into an electron beam irradiation apparatus, and the adhesive layer was irradiated with energy of 200 KV and 18 Mrad from the side of the separate film (DE) to crosslink the adhesive layer. The laminate (vi ′) having the adhesive layer (C) was rolled up. In the manufacturing process so far, the occurrence of the channeling phenomenon of the separate film (DE) was not observed.

  Table 1 shows the characteristics of the protective film for display screen obtained in Example 1 and the characteristics of the coating liquid for forming the adhesive layer (C).

  The protective film for display screens obtained in this example is excellent in transparency, and the adhesive layer (C) is strong with the polyester base film (A) through the heat resistant water adhesion improving layer (B). It was excellent in adhesion and hot water adhesion. Moreover, the peeling force between the release layer (D) and the pressure-sensitive adhesive layer (C) was moderate and excellent in peelability, and it was a high-quality display screen protective film. Furthermore, it was also excellent in the clarity and stability of the coating liquid for forming the adhesive layer (C) in the production of the protective film for display screens, and it was confirmed that it was excellent in operability and operational stability. .

Comparative Example 1
In the method of Example 1, a protective film for display screen was obtained in the same manner as in Example 1 except that the application of the coating liquid (B-1) for forming the heat resistant water adhesion improving layer (B) was stopped. It was. The evaluation results are shown in Table 1.

  The protective film for display screen obtained in Comparative Example 1 is more resistant to water and water than the film of Example 1 in adhesiveness and adhesion between the pressure-sensitive adhesive layer (C) and the polyester-based substrate film (A). The quality was inferior and the quality was low.

Comparative Example 2
In the method of Example 1, it was the same as Example 1 except that the blending of the methylolated melamine resin as a crosslinking agent was stopped in the coating liquid (B-1) for forming the heat resistant water adhesion improving layer (B). Thus, a protective film for display screen was obtained. The evaluation results are shown in Table 1.

  The protective film for display screen obtained in this Comparative Example 2 has good peel strength between the adhesive layer (C) / release layer (D) and between the polyester-based substrate film (A) / adhesive layer (C). However, the heat resistant water adhesion between the pressure-sensitive adhesive layer (C) and the polyester base film (A) was inferior.

Comparative Example 3
In the method of Example 1, the same method as in Example 1 except that the combination of the polymer wax component and the antistatic agent in the coating liquid (D-1) for forming the release layer (D) was stopped. A protective film for display screen was obtained. The evaluation results are shown in Table 1.

  The protective film for display screen obtained in Comparative Example 3 tried to peel the separate film (DE) from the adhesive layer (C), but could not be peeled off, and the peelability was poor. Therefore, since it cannot be used as a protective film for a display screen, no evaluation other than the peel strength was performed.

Comparative Examples 4 and 5
In the method of Example 1, in the release layer (D) forming coating liquid (D-1), the polymer wax component in Comparative Example 4 and the blending of the antistatic agent in Comparative Example 5 are stopped. Except for the above, a display screen protective film was obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

  The protective film for display screen obtained in Comparative Example 4 could not separate the separate film (DE) from the adhesive layer (C). Therefore, the surface protective film of Comparative Example 4 was not evaluated except for the peel strength. In Comparative Example 5, the peel strength of the separate film (DE) was high, and the peelability of the separate film (DE) was inferior.

Comparative Example 6
In the method of Example 1, the same method as in Example 1 was used, except that a silicone-treated polyester film for release having a thickness of 38 μm (E7002; manufactured by Toyobo Co., Ltd.) was used as the separate film (DE). A protective film for display screen was obtained. The evaluation results are shown in Table 1.

  The protective film for display screen obtained in this Comparative Example 6 tried to peel the separate film (DE) from the adhesive layer (C) as in Comparative Example 3, but could not be peeled off and was inferior in peelability. It is presumed that the cross-linking adhesion phenomenon occurred due to the EB cross-linking. Therefore, it could not be used as a display screen protective film. The surface protective film of Comparative Example 6 was not evaluated except for the peel strength.

Comparative Example 7
In the method of Example 1, a display screen protective film was obtained in the same manner as in Example 1 except that the thickness of the heat resistant water adhesion improving layer (B) was changed to 0.7 μm. The evaluation results are shown in Table 1.

  The display screen protective film obtained in Comparative Example 7 has good adhesion between the pressure-sensitive adhesive layer (C) / release layer (D) and between the polyester-based substrate film (A) / pressure-sensitive adhesive layer (C). However, compared with the display screen protective film of Example 1, the adhesive layer (C) was inferior in heat resistant water adhesion.

Comparative Example 8
In the method of Comparative Example 2, a protective film for display screen was obtained in the same manner as in Comparative Example 2, except that the preparation of the coating liquid for forming the adhesive layer (C) was changed as shown below. The evaluation results are shown in Table 1.

[Preparation of adhesive layer (C) forming coating solution]
High transparency silicone rubber compound ("TSE260-3U"; rubber hardness 30 degrees) consisting of 60 parts of a polydimethylsiloxane skeleton silicone compound, 25 parts of a polydimethylalkenylsiloxane skeleton silicone compound and 15 parts of silica; Momentive Performance Materials (Made by Japan) was weighed so that the mass ratio with respect to toluene might be 23%, and it poured into the stirrer with a vacuum degassing apparatus with toluene, and it stirred at room temperature for 15 hours under atmospheric pressure, and was dissolved in toluene. To the obtained solution, trimethylolpropane trimethacrylate was added so as to be 2 parts with respect to 100 parts of the rubber compound, and after stirring uniformly, the vacuum deaerator was driven and the gauge pressure was -750 mmHg. The mixture was further stirred for 20 minutes and degassed. In addition, the said silicone rubber compound used what passed 6 months after purchase.

  In addition to the problem of the display screen protective film obtained in Comparative Example 2, the display screen protective film obtained in Comparative Example 8 was inferior in the clarity and storage stability of the coating solution.

Reference example 1
In the method of Example 1, 8 parts of organic silicone (“KS-744”; manufactured by Shin-Etsu Chemical Co., Ltd.) and a catalyst “PL-3” (Shin-Etsu) were used as the coating liquid for forming the heat resistant water adhesion improving layer (B). A double-sided PSA sheet was obtained in the same manner as in Example 1 except that 0.06 part (made by Chemical Industry Co., Ltd.) was changed to a solution in which 100 parts by mass of toluene was dissolved. The evaluation results are shown in Table 1.

  The double-sided PSA sheet obtained in Reference Example 1 was inferior in heat-resistant water adhesion between the PSA layer (C) and the polyester-based substrate film (A), and was of low quality.

Example 2
In the production of the polyester-based substrate film (A) of Example 1, the polyester-based substrate film (A) was produced in the same manner as in Example 1 except that the application of the coating liquid (B-1) was stopped. -2) was obtained. Corona treatment was performed on both sides of this polyester base film (A-2). Separately, a copolymerized polyester resin solution (“Byron (registered trademark) 30SS”; manufactured by Toyobo Co., Ltd.) and a polyisocyanate-based crosslinking agent (“Coronate (registered trademark) HX”; manufactured by Nippon Polyurethane Co., Ltd.) It mix | blended so that it might become 100: 3 (part), and prepared the coating liquid (B-2) for heat-resistant water adhesive improvement layers (B). This coating liquid (B-2) was applied to both sides of the polyester base film (A-2) after the corona treatment using a coater and dried. The laminated body by which the hot-water-resistant adhesiveness improvement layer (B-2) bridge | crosslinked by the both sides of the polyester-type base film (A-2) was laminated | stacked was obtained. Using this laminate, a protective film for display screen was obtained in the same manner as in Example 1. In addition, the thickness of the hot water resistant adhesiveness-improving layer (B-2) after biaxial stretching was 0.31 μm. The evaluation results are shown in Table 2.

  The display screen protective film obtained in this example had the same characteristics as the display screen protective film obtained in Example 1, and was of high quality.

Comparative Example 9
In the preparation of the coating liquid (B-2) of Example 2, in the same manner as in Example 1, except that the formulation of “Coronate HX” as a crosslinking agent was canceled and only “Byron 30SS” was used. A protective film for display screen was obtained. The evaluation results are shown in Table 2.

  The protective film for display screen obtained in Comparative Example 9 has good peelability between the adhesive layer (C) / release layer (D) and between the polyester base film (A) / adhesive layer (C). However, the adhesive layer (C) had poor heat-resistant water adhesion.

Examples 3-6
A protective film for a display screen was obtained in the same manner as in Example 1 except that the coating solution for heat resistant water adhesion improving layer (B-1) in Example 1 was changed to the following composition. The evaluation results are shown in Table 2.

  The protective film for display screens obtained in these examples had the same characteristics as the protective film for display screens obtained in Example 1, and was high quality.

[Coating fluid for heat resistant water adhesion improving layer of Example 3]
10 parts of the “Cymel 303” and 0.04 part of the “Catalyst 600” with respect to 100 parts of the solid content of the acrylic emulsion (“Joncrill (registered trademark) PDX-7630A”; manufactured by BASF Japan). Were mixed to obtain a coating solution for heat resistant water adhesion improving layer (B-3).

[Coating fluid for heat resistant water adhesion improving layer of Example 4]
As an oxazoline-based cross-linking agent ("Epocross (registered trademark) WS-700"; Nippon Shokubai Co., Ltd.) with respect to 100 parts of a solid content of a polyurethane-based aqueous dispersion ("Hydran (registered trademark) AP40"; manufactured by Dainippon Ink and Industry). 3 parts by solid content was added to obtain a coating solution for heat resistant water adhesion improving layer (B-4).

[Coating fluid for heat resistant water adhesion improving layer of Example 5]
7.5 parts of water-dispersible copolyester “Vylonal (registered trademark) MD-1200” (manufactured by Toyobo Co., Ltd.), 20% aqueous solution of self-crosslinking polyurethane containing isocyanate groups blocked with sodium bisulfite (“Elastron ( (Registered trademark) H-3 "; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 11.3 parts, catalyst for elastron (" Cat 64 "; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.3 parts, water 39.8 parts and isopropyl alcohol Four parts were placed in a container and mixed well.

  Further, 0.6 parts of a 10% aqueous solution of a fluorine-based nonionic surfactant (“Megafac (registered trademark) F142D”; manufactured by Dainippon Ink & Chemicals, Inc.), colloidal silica (“Snowtex (registered trademark) OL”) Average particle size 40 nm; 2.3 parts of 20% aqueous dispersion of Nissan Chemical Industries, Ltd., dry silica (“Aerosil OX50”; “Aerosil” is a registered trademark of Degussa; average particle size 200 nm; average primary particle; 0.5 parts of a 3.5% aqueous dispersion of 40 nm in diameter; manufactured by Nippon Aerosil Co., Ltd. was added. Next, the pH of the coating solution is adjusted to 6.2 with a 5% aqueous sodium bicarbonate solution, and the solution is precisely filtered through a felt type polypropylene filter having a filtration particle size (initial filtration efficiency: 95%) of 10 μm, and is resistant to hot water. It was set as the coating liquid for improved layers (B-5).

[Coating fluid for heat resistant water adhesion improving layer of Example 6]
40 parts of a self-crosslinking polyester resin aqueous dispersion “Vylonal (registered trademark) AGN702” (manufactured by Toyobo Co., Ltd.), 24 parts of water and 36 parts of isopropyl alcohol are mixed, and a 10% aqueous solution of an anionic surfactant 0.6 Part, propionate 1 part, colloidal silica particles (“Snowtex (registered trademark) OL”; average particle size 40 nm; manufactured by Nissan Chemical Industries, Ltd.)) 1.8% 20% aqueous dispersion, dry process silica particles (“ Aerosil OX50 "; average particle size 200 nm; average primary particle size 40 nm; manufactured by Nippon Aerosil Co., Ltd. did.

Example 7
In the method of Example 1, a display screen protective film was obtained in the same manner as in Example 1 except that a separate film (DE-2) produced by the following method was used. The evaluation results are shown in Table 2.

[Preparation of Separate Film (DE-2)]
The coating liquid (D-1) used in the production of the separate film (DE-1) of Example 1 was applied onto a polyester film (A: 100 μm) using a wire bar (No. 5). The coating amount of the coating liquid (D-1) was about 8 to 10 g (wet state) per 1 m ^{2 of the} base film. The film was dried at 160 ° C. for about 60 seconds to obtain a separate film (DE-2).

  The display screen protective film obtained in Example 7 had the same characteristics as the display screen protective film obtained in Example 1 and was of high quality. Further, as in Example 1, the separation film (DE) was not lifted during the production of the display screen protective film.

Example 8
In the method of Example 1, the polymer wax of the release layer coating solution used for the production of the separate film (DE-1) was converted into an acrylic wax agent emulsion (“ST-200”; manufactured by Nippon Shokubai Co., Ltd.). A display screen protective film was obtained in the same manner as in Example 1 except that the change was made. The evaluation results are shown in Table 2.

  The display screen protective film obtained in Example 8 had the same characteristics as the display screen protective film obtained in Example 1 and was of high quality. Further, as in Example 1, the separation film (DE) was not lifted during the production of the display screen protective film.

Example 9
In the method of Example 1, the antistatic agent of the release layer coating solution used for the production of the separate film (DE-1) was changed to an anionic antistatic agent (“TB214”; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). Except for this, a double-sided PSA sheet was obtained in the same manner as in Example 1. The evaluation results are shown in Table 3.

  The display screen protective film obtained in Example 9 had the same characteristics as the display screen protective film obtained in Example 1 and was of high quality. Further, as in Example 1, the separation film (DE) was not lifted during the production of the display screen protective film.

Example 10
In the method of Example 1, the polymer wax component of the release layer coating solution used for the production of the separate film (DE-1) was changed to 0.2% and the antistatic agent to 0.3%. A display screen protective film was obtained in the same manner as in Example 1 except that. The evaluation results are shown in Table 3.

  The display screen protective film obtained in Example 10 had the same characteristics as the display screen protective film obtained in Example 1 and was of high quality. Further, as in Example 1, the separation film (DE) was not lifted during the production of the display screen protective film.

Comparative Example 10
In the method of Example 1, the polymer wax component of the release layer coating solution used for the production of the separate film (DE-1) was changed to 1.3% and the antistatic agent to 1.5%. A double-sided PSA sheet was obtained in the same manner as in Example 1 except that. The evaluation results are shown in Table 3.

  The peel strength of the separate film (DE) of the double-sided pressure-sensitive adhesive sheet obtained in Comparative Example 10 was approximately 0 N / 20 mm, and the peelability was very good. However, when the protective film for display screen was produced, the separate film (DE) may occur.

Example 11
Using the coating liquid for the adhesive layer (C) prepared by the following method on the surface of the laminate (iv) which is a separate film prepared in the method of Example 1, the adhesive layer ( C) was laminated to obtain a laminate (vii). The pressure roller (pressure 30 N / cm ² ) was applied to the surface of the pressure-sensitive adhesive layer (C) of the obtained laminate (vii) while the surface of the laminate (iii) produced in Example 1 was improved in the heat resistant water adhesion improving layer (B). ) And laminated continuously. The obtained laminate (viii) was further continuously introduced into an electron beam irradiation apparatus, and irradiated with an electron beam at an energy of 200 KV and 18 Mrad from the laminate (iv) side, which is a separate film, to form an adhesive layer (C- Crosslinking of 2) was performed, and the laminate (viii ′) after crosslinking was wound into a roll. In the manufacturing process so far, the occurrence of the channeling phenomenon of the separate film (DE) was not observed.

  The display screen protective film obtained in this example had the same characteristics as the display screen protective film obtained in Example 1 and was of high quality.

[Preparation of coating solution for adhesive layer (C-2)]
A non-reactive silicone compound (KF-96H-1 million) comprising an uncrosslinked polydimethylsiloxane skeleton having substantially no reinforcing agent such as silica and having a number average molecular weight of 170,000 (measured by GPC method, converted to polystyrene) cs; manufactured by Shin-Etsu Chemical Co., Ltd.) was weighed so that the mass ratio with respect to toluene was 23%, and was put together with toluene into a stirrer equipped with a vacuum deaerator and stirred in atmospheric pressure at room temperature for 15 hours to dissolve in toluene. I let you. To the obtained solution, trimethylolpropane trimethacrylate was added to 100 parts of the silicone compound so as to be 2 parts, and after stirring uniformly, the vacuum deaerator was driven and the gauge pressure was -750 mmHg. Stir under vacuum for another 20 minutes and degas.

  The protective film for the display screen of the image display device of the present invention has a sticking mistake because an adhesive layer containing a cross-linked silicone compound having a polydimethylsiloxane skeleton having both sticking property and removability is formed. In this case, it can be easily peeled off and reattached.

  The manufacturing method of the protective film for display screens of this invention can manufacture the protective film for display screens which has the said characteristic economically. In particular, since the adhesive layer is formed by crosslinking an uncrosslinked polydimethylsiloxane skeleton silicone compound, it is more transparent than a silicone rubber layer made from a conventionally known millable silicone rubber compound. In addition, since it is excellent in clarity and operability, it is excellent in cost performance as compared with conventionally known methods.

Claims (9)

A protective film for a display screen of an image display device,
Polyester base film (A), heat resistant water adhesion improving layer (B), adhesive layer (C) comprising a crosslinked silicone compound having a polydimethylsiloxane skeleton, binder resin, polymer wax component and antistatic agent A release film (D) and a polyester film (E) made of a non-silicone compound containing a protective film for display screens laminated in the order of A to E,
Peel strength of the adhesive layer to be measured by the following peel Measurement methods and (C) a release layer and (D) is Ri 0.03~1.0N / 20mm der, and,
A protective film for a display screen , wherein the adhesive layer (C) does not peel when the hot water adhesion is evaluated by the following method .
[Peelability]
A protective film sample for a display screen having a length of about 200 mm and a width of 20 mm is peeled off slightly at the interface between the adhesive layer (C) and the release layer (D) to expose each of the adhesive layer (C) and the release layer (D). Let Next, the laminate of the polyester base film (A) to the adhesive layer (C) is held with one chuck of the tensile tester, and from the release layer (D) and the polyester film (E) with the other chuck. A separate film (DE) is gripped, a T-type peel test is performed under the conditions of a distance between chucks of 50 mm, a temperature of 23 ° C., and a tensile speed of 200 mm / min, and the maximum strength at the time of T-type peel is defined as the peel strength.
[Heat resistant water adhesion]
The protective film for display screen is cut to 50 mm x 50 mm, the separate film (DE) consisting of the polyester film (E) and the release layer (D) is peeled off, and a cylindrical shape with a 500 cc lid containing 400 cc of distilled water In the glass container, the sample is submerged in water so that the adhesive layer (C) is on the lower side, and the container is covered with the entire sample immersed in water.
The container containing the sample is placed in a gear oven set at 80 ° C., left to stand for 24 hours, heat-treated, and then the surface of the adhesive layer (C) of the sample taken out of the oven is directed from the end of the sample toward the center. Applying force with the finger pad and rubbing 10 times, it is evaluated whether or not the adhesive layer (C) is peeled from the polyester base film (A) side. The case where the pressure-sensitive adhesive layer (C) does not peel is evaluated as ◯, and the case where the pressure-sensitive adhesive layer (C) peels is evaluated as x. The protective film for a display screen according to claim 1, wherein the crosslinked silicone compound is obtained by crosslinking an uncrosslinked product of a silicone compound having a polydimethylsiloxane skeleton having a number average molecular weight of 50,000 to 500,000. The protective film for display screen according to claim 1 or 2 , wherein the thickness of the heat resistant water adhesion improving layer (B) is 0.01 to 0.5 µm. The hot-water proof adhesion improving layer (B) is polyester, and one or more polymers selected from the group consisting of polyurethane and acrylic polymers, according to claim 1 to 3 comprising the reaction product of a crosslinking agent The protective film for display screens in any one. The crosslinking agent is a melamine crosslinking agent, oxazoline crosslinking agent, isocyanate crosslinking agent, aziridine crosslinking agent, epoxy crosslinking agent, methylolated or alkylolized urea crosslinking agent, acrylamide crosslinking agent, polyamide resin. The display screen protective film according to claim 4 , which is at least one selected from the group consisting of amide epoxide compounds, silane coupling agents, and titanate coupling agents. 2. The heat-resistant water adhesion improving layer (B) contains a self-cross-linked one or more self-cross-linked polymers selected from the group consisting of self-crosslinking polyesters, polyurethanes and acrylic polymers. display screen protection film according to any one of 1 to 4. A method of manufacturing a display screen protection film according to any one of claims 1 to 6
A step of laminating the heat resistant water adhesion improving layer (B) on one side of the polyester base film (A) to form a laminate (1);
A step of laminating a layer containing an uncrosslinked product of a silicone compound having a polydimethylsiloxane skeleton on the surface of the heat resistant water adhesion improving layer (B) of the laminate (1) to form a laminate (2);
A step of laminating a release layer (D) made of a non-silicone compound containing a binder resin, a polymer wax component and an antistatic agent on one side of the polyester film (E) to form a laminate (3);
The laminates (2) and (3) are formed so that the release layer (D) of the laminate (3) is in contact with the surface of the layer (2) containing a non-crosslinked silicone compound having a polydimethylsiloxane skeleton. ) And forming a laminate (4),
A step of crosslinking a non-crosslinked body of the silicone compound having a polydimethylsiloxane skeleton of the laminate (4) to form a laminate (4 ′) having an adhesive layer (C);
The manufacturing method of the protective film for display screens characterized by including. A method of manufacturing a display screen protection film according to any one of claims 1 to 6
Forming the laminate (3) according to claim 7 ,
A layer containing an uncrosslinked product of a silicone compound having a polydimethylsiloxane skeleton on the surface of a release layer (D) comprising a non-silicone compound containing a binder resin, a polymer wax component and an antistatic agent of the laminate (3) A step of forming a laminate (5),
Forming the laminate (1) according to claim 7 ,
Layer containing uncrosslinked silicone compounds having a polydimethylsiloxane skeleton of the laminate (5) is laminated in contact with the surface of the heat water adhesion improving layer of the layered product (1) (B), claim 7 A step of forming the laminate (4) according to claim 1,
Forming the laminate (4 ') according to claim 7 ,
The manufacturing method of the protective film for display screens characterized by including. The silicone compound containing the polydimethylsiloxane skeleton is mainly composed of a silicone compound having a number average molecular weight of 50,000 to 500,000, and an acrylic acid ester of a polyhydric alcohol and a methacrylic polyhydric alcohol as an adhesion improver. The method for producing a protective film for a display screen according to claim 7 or 8 , wherein the protective film is formed from a composition containing at least one of an acid ester.