JP4611858B2 - Protective film for optics - Google Patents

Description

  The present invention relates to an optical protective film used in manufacturing a polarizing plate used for a liquid crystal display. More specifically, the present invention relates to an optical protective film provided with antistatic properties, easy cleaning of contaminants, and scratch prevention functions.

  A general optical protective film has a structure of surface protective layer / water resistant layer / antistatic layer / base film / antistatic layer / adhesive layer / separate film layer, and one side of the base film (separate film layer) Side) is the side to be bonded to the polarizing plate and consists of a separate film layer, an adhesive layer and an antistatic layer. The adhesive layer uses an adhesive with little adhesive residue, and the antistatic layer has an antistatic function. Has been granted. The other surface of the optical protective film is composed of an antistatic layer, a water resistant layer and a surface protective layer. The antistatic layer is as described above, and the water resistant layer is formed by removing the antistatic layer from the external environment (humidity). There is a function to minimize the influence, and the surface protective layer has many functions.

  At the time of manufacturing a polarizing plate used for liquid crystal displays, an optical protective film is bonded to the surface of the polarizing plate so that the polarizing plate is not soiled or scratched, and the optical protective film is peeled off from the polarizing plate at the time of use. Is.

  The reason for imparting an antistatic function to the adhesive layer side of the protective film for optics is that defective products may occur due to dust generated by the process of manufacturing a polarizing plate or static electricity generated when peeling from the polarizing plate. So to prevent it.

  Further, the surface protective layer on the outer side of the other surface different from the adhesive layer of the optical protective film is provided with antistatic, scratch prevention, easy cleaning of contaminants, and the like. The necessity to give each is as follows. The antistatic function is as described above, and the scratch prevention function is intended to prevent scratches that occur during the manufacturing process of the polarizing plate, and in particular, the polarizing plate and the optical protective film are attached with a roll. When aligning, cut according to the required specifications as a polarizing plate, and when it is laminated and stored, or when it is extracted during storage, it is easy to be damaged, so it is for dealing with these .

  Contaminant easy-cleaning properties: Adhesive attached to protective layer when laminating polarizing plate and optical protective film, or attached when laminated and stored, cut according to necessary specifications as polarizing plate This is because the pressure-sensitive adhesive or the like contaminates the surface of the optical protective film and becomes a problem as a defective product in appearance inspection, so that it can be easily wiped off. As a method for removing the adhesive attached to the optical protective film, for example, there is a method of performing dry wiping or wiping with a cloth soaked with an organic solvent such as alcohol or ethyl acetate. Easy cleaning is required at the time of such wiping.

  As an example of the production of an optical protective film having the above functions, an acrylic pressure-sensitive adhesive is applied to one side of the base film, and a silicone acrylate is applied to the other side of the base film that has been subjected to antistatic treatment. Example of coating (see Patent Document 1) that prevents film blocking during stacking by sticking out the adhesive of the protective film for optical use and easy cleaning of contaminants, and polyvinyl alcohol or polyethyleneimine on the surface protective layer Examples have been proposed in which a long-chain alkylated copolymer or the like is applied and a function that prevents the adhesive protruding from the cut surface from adhering to the surface of the optical protective film is given (see Patent Documents 2 and 3). ing.

In addition to the antistatic properties, scratch prevention, and easy cleaning of contaminants, the surface protective layer of the optical protective film has printing suitability (printer ink suitability for process control), film substrate Adhesion, scratch resistance, and moderate slipperiness are also required.
JP 2001-305346 A JP 11-256115 A JP 11-256116 A

  However, the proposed technique does not satisfy all the functions described above. In addition, there is a demand for a material for forming a surface protective layer for an optical protective film that has higher performance than before. From the current 3-coat system (surface protective layer / water resistant layer / antistatic layer / base film) to the 2-coat system (surface protective layer / antistatic layer / base film) For the purpose of simplifying the manufacturing method, there is also a demand for a change in the configuration system to a one-coat system (surface protective layer / base film having an antistatic function).

Therefore, the object of the present invention is to provide antistatic properties, scratch resistance, easy cleaning of contaminants (solvent resistance is also required because it may be washed with an organic solvent), printability (used for process control) To provide an optical protective film having adhesiveness with a substrate film, transparency, moderate slipperiness, and the like.
Furthermore, an object of the present invention is to provide an optical protective film capable of a one-coat system of antistatic surface protective layer / base film as the structure of the surface protective layer.

The above object is achieved by the present invention having the following constitution.
1. From a base film, an adhesive layer provided on one side of the base film, and an antistatic surface protective layer (surface protective layer having an antistatic function) provided on the other side of the base film in the optical protective film consisting of the antistatic surface protective layer, the resin (a) having an active hydrogen group in the molecule, a polyurethane resin containing a polysiloxane group (B), the polyisocyanate (C), The polyurethane resin (B), which is formed by coating one coat using the carbon nanotube (D) as a film-forming component, is a polysiloxane compound having a hydroxyl group at both ends, A compound obtained by copolymerizing a polysiloxane compound having at least one active hydrogen group and a lactone, a polyisocyanate, a polyol or a poly Protective film for optical, characterized in that a polyurethane resin obtained by reacting an amine.

2. Resin (A) having an active hydrogen group in the molecule is polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl Alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin 2. The optical protective film as described in 1 above, which is at least one selected from alkyd resins, phenol resins, polyethers, polyesters, celluloses, chitosan and urethane resins.

3. 2. The protective film for optics according to 1, wherein the polyurethane resin (B ) containing the polysiloxane group has a weight average molecular weight of 5,000 to 500,000.

4). ^2. The optical protective film as described in 1 above, wherein the surface resistance value is 10 ¹⁰ Ω / cm ² or less.
5. 2. A paint for forming an antistatic surface protective layer in the optical protective film according to 1 above, wherein the resin (A) has an active hydrogen group in the molecule and a polyurethane resin (B) contains a polysiloxane group. ) And carbon nanotubes (D) are dissolved or dispersed in an organic solvent, and polyisocyanate (C) is added before use, or stabilized polyisocyanate (C) is contained. A polyurethane resin (B) containing a siloxane group, a polysiloxane compound having hydroxyl groups at both ends, or a compound in which a polysiloxane compound having at least one active hydrogen group in the molecule and a lactone are copolymerized; A polyurethane resin obtained by reacting a polyisocyanate with a polyol or a polyamine. Surface for forming a protective layer paint that.

6). The resin (A) is an ethylene - vinyl alcohol copolymer, partially saponified polyvinyl alcohol or a phenoxy resin a paint according to the 5 is.

7). Resin (A) is 15-95 mass% of the total amount (100 mass%) of resin (A), resin (B), and carbon nanotube (D), and resin (B) is 60-5 mass. %, And the carbon nanotube (D) is 25 to 0.1% by mass .

  According to the present invention, the construction system of the surface protective layer of the optical protective film comprises a one-coat system such as an antistatic surface protective layer / base film, and is antistatic, scratch resistant, easy to clean contaminants, Provided is an optical protective film excellent in printability, adhesion to a substrate film, transparency, moderate slipperiness, and the like.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a base film, an adhesive layer provided on one side of the base film, and a charging provided on the other side of the base film. In an optical protective film comprising a protective surface protective layer (hereinafter sometimes referred to simply as “surface protective layer”), the surface protective layer is made of a polyurethane containing a resin having an active hydrogen group in the molecule and a polysiloxane group. The present inventors have found that an optical protective film having an excellent function can be obtained by forming a resin, a polyisocyanate, and a carbon nanotube as a film-forming component. A resin having an active hydrogen group in the molecule, a polyurethane resin containing a polysiloxane group, and a polyisocyanate bring out surface characteristics such as easy cleaning and scratch resistance, and carbon nanotubes exhibit antistatic properties.

Next, the present invention will be described in more detail with reference to preferred embodiments.
The optical protective film of the present invention comprises a base film, an adhesive layer provided on one surface of the base film, and a surface protective layer provided on the other surface of the base film. That is, the structure of the optical protective film on the surface protective layer side is characterized by the structure of a one-coat system such as a surface protective layer / base film, and the structure of a conventional three-coat system (surface protective layer / water resistant layer). / Antistatic layer / base film) or a two-coat system construction (surface protective layer / antistatic layer / base film). That is, the surface protection layer is excellent in cost performance by reducing the number of coatings during production.

  Next, the surface protective layer will be described in detail. The surface protective layer is formed using a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, a polyisocyanate (C), and a carbon nanotube (D) as a film forming component. It is preferable that these materials are dissolved in a solvent or the like, or applied onto a substrate film as a coating material for forming a surface protective layer and dried without solvent to form a surface protective layer. The coating material for forming the surface protective layer in this case contains a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, a polyisocyanate (C), and a carbon nanotube (D). is doing.

  Examples of the resin (A) having an active hydrogen group in the molecule include polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, Ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin , Melamine resin, alkyd resin, phenol resin, polyether, polyester, celluloses, chitosan and urethane resin. Furthermore, at least one selected from these is preferably used. Of these, ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol and phenoxy resin are particularly preferable. Furthermore, resins obtained by modifying acrylic resins, phenoxy resins, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, butyral group-modified polyvinyl alcohols with fluorine-modified silicone groups or long-chain alkyl groups can also be used.

The active hydrogen group in the resin (A) having an active hydrogen group in the molecule is, for example, a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NRH (R: hydrocarbon group), —NH _2. Etc.) and a thiol group (-SH). Among these, a hydroxyl group is preferably used. When the resin has an active hydrogen group in the molecule, it can be used as it is as the resin (A), but when the resin does not have an active hydrogen group in the molecule, a treatment such as modification is performed. To give an active hydrogen group.

  The polyurethane resin (B) containing a polysiloxane group will be described below. The polysiloxane group is contained as a polysiloxane segment in the polyurethane resin (B), and is contained in the main chain of the polyurethane resin or in a branched state. That is, if the polysiloxane used as a raw material is a double-end reactive type, it is contained in the trunk portion which is the main chain of the polyurethane resin, and if it is a single-end or branched reaction type, it is contained in a state branched from the main chain of the polyurethane resin. Become.

  As the polyurethane resin (B) containing a polysiloxane group, the following are preferably used. A polysiloxane group obtained by reacting a polysiloxane compound having at least one active hydrogen group in the molecule and / or a compound obtained by copolymerizing the polysiloxane compound and a lactone, a polyisocyanate, and a polyol or polyamine. The preferred weight average molecular weight is 5,000 to 500,000.

The raw material component used as the said polysiloxane group used by this invention is demonstrated.
As the polysiloxane compound having at least one active hydrogen group used in the present invention, for example, the following compounds are preferably used (in this, an epoxy-modified polysiloxane modified by using active hydrogen groups). A siloxane compound is also included, but it is included because it reacts with an isocyanate group and is contained in a polyurethane resin).

(1) Amino-modified polysiloxane compound

(2) Epoxy-modified polysiloxane compound

上記のエポキシ変性ポリシロキサン化合物はポリオール、ポリアミド、ポリカルボン酸などと反応させ末端活性水素を有するようにして使用することができる。

The epoxy-modified polysiloxane compound can be used by reacting with a polyol, polyamide, polycarboxylic acid or the like so as to have terminal active hydrogen.

(3) Alcohol-modified polysiloxane compound

(4) Mercapto-modified polysiloxane compound

  The polysiloxane compounds having active hydrogen groups listed above are preferred compounds used in the present invention, but the present invention is not limited to these exemplified compounds. Accordingly, not only the above-exemplified compounds but also other compounds that are currently commercially available and can be easily obtained from the market can be preferably used in the present invention. Particularly preferred compounds in the present invention are polysiloxane compounds having two hydroxyl groups or amino groups.

  In addition to these, a polylactone (polyester) -polysiloxane compound obtained by modifying a polysiloxane compound with a lactone, a polyethylene oxide-polysiloxane compound modified with ethylene oxide or propylene oxide, a polypropylene oxide-polysiloxane compound, and the like are also preferably used. Particularly preferred are compounds obtained by modifying polysiloxane compounds with lactones, and more preferred are polylactone-polysiloxane compounds obtained by modifying polysiloxane compounds having one or more active hydrogen groups in the molecule with lactones. Preferred lactones used here are β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, 7-heptanolide, 8-octanolide, γ-valerolactone, γ-caprolactone and δ-caprolactone. .

  In the present invention, the polylactone-polysiloxane compound, that is, the polylactone-polysiloxane compound obtained by modifying a polysiloxane compound having at least one active hydrogen group in the molecule with a lactone is one or more in the molecule. An active hydrogen atom group of a siloxane compound having an active hydrogen group, for example, an amino group, a hydroxyl group, a carboxyl group or the like, is obtained by subjecting the lactone to ring-opening polymerization and then subjecting it to a reduced pressure treatment.

  The polyol used in the polyurethane resin (B) containing a polysiloxane group is preferably a conventionally known one such as a short-chain diol, a polyhydric alcohol compound and a polymer polyol conventionally used in the production of polyurethane. However, as the polyamine, a short-chain diamine conventionally used in the production of polyurethane can be used, but these are not particularly limited. Each compound used below is described.

  Examples of the short-chain diol include aliphatic glycols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, and neopentyl glycol. And its alkylene oxide low mole adduct (number average molecular weight less than 500), alicyclic glycols such as 1,4-bishydroxymethylcyclohexane and 2-methyl-1,1-cyclohexanedimethanol, and its alkylene oxide low mole Adducts (number average molecular weight less than 500), aromatic glycols such as xylylene glycol and their alkylene oxide low molar adducts (number average molecular weight less than 500), bisphenol A, thiobisphenol and sulfone bisphenol Phenols and alkylene oxide low mol adduct (number average molecular weight of less than 500), and compounds such as alkyl dialkanolamines, such as alkyl diethanolamine of C1~C18 thereof. Examples of the polyhydric alcohol compound include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, tris- (2-hydroxyethyl) isocyanurate, 1,1,1-trimethylolethane, and 1,1, Examples thereof include 1-trimethylolpropane. These can be used alone or in combination of two or more.

Examples of the polymer polyol include the following.
(1) Polyether polyols such as those obtained by polymerizing or copolymerizing alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.) and / or heterocyclic ethers (tetrahydrofuran, etc.) are specifically exemplified. Are polyethylene glycol, polypropylene glycol, polyethylene glycol-polytetramethylene glycol (block or random), polytetramethylene ether glycol and polyhexamethylene glycol,

(2) Polyester polyols such as aliphatic dicarboxylic acids (eg succinic acid, adipic acid, sebacic acid, glutaric acid and azelaic acid) and / or aromatic dicarboxylic acids (eg isophthalic acid and terephthalic acid) And low molecular weight glycols (for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol and 1,4-bishydroxy For example, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butyle. Adipate diol, polyneopentyl / hexyl adipate diol, poly-3-methylpentane adipate diol, and polybutylene isophthalate diol, etc.,

(3) Polylactone polyols such as polycaprolactone diol or polycaprolactone triol and poly-3-methylvalerolactone diol,
(4) Polycarbonate diol, such as polyhexamethylene carbonate diol,
(5) Polyolefin polyol, such as polybutadiene glycol and polyisoprene glycol, or a hydride thereof,
(6) Polymethacrylate diols such as α, ω-polymethylmethacrylate diol and α, ω-polybutylmethacrylate diol are exemplified.

  Although the molecular weight of these polyols is not particularly limited, the number average molecular weight is usually preferably about 500 to 2,000. Moreover, these polyols can be used individually or in combination of 2 or more types.

  Examples of preferred polyamines as the polyamine include short-chain diamines, aliphatic, aromatic diamines, and hydrazines. Examples of the short-chain diamine include aliphatic diamine compounds such as ethylene diamine, trimethylene diamine, hexamethylene diamine and octamethylene diamine, phenylene diamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane, and 4,4 ′. -Aromatic diamine compounds such as methylene bis (phenylamine), 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl sulfone, cyclopentanediamine, cyclohexyldiamine, 4,4-diaminodicyclohexylmethane, 1,4-diamino And alicyclic diamine compounds such as cyclohexane and isophorone diamine. Further, hydrazines such as hydrazine, carbohydrazide, adipic acid dihydrazide, sebacic acid dihydrazide and phthalic acid dihydrazide can be mentioned. These can be used alone or in combination of two or more. As the polyol and polyamine, a diol compound and a diamine compound are preferable.

  As the polyisocyanate compound used for the synthesis of the polyurethane resin (B) containing the polysiloxane group, any of those conventionally used for producing a polyurethane can be used and is not particularly limited. Preferred examples of the polyisocyanate compound include toluene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, and 4-chloro-1,3-phenylene diisocyanate. 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4′-methylenebis (phenylene isocyanate) (MDI), jurylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate (XDI), 1, Aromatic diisocyanates such as 5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate and 4,4′-diisocyanate dibenzyl, methyl Diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate and other aliphatic diisocyanates, 1,4-cyclohexylene diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate) 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, alicyclic diisocyanates such as hydrogenated MDI and hydrogenated XDI, etc., or these diisocyanate compounds and low molecular weight polyols or polyamines are reacted so that the terminal is isocyanate. Naturally, the obtained polyurethane prepolymer can also be used.

  In the polyurethane resin (B) containing a polysiloxane group, the method for producing a polyurethane resin containing a polysiloxane group using the above raw materials is not particularly limited, and a conventionally known method for producing a polyurethane can be used. For example, a compound in which at least one active hydrogen group and a polysiloxane segment coexist in the same molecule in the presence or absence of an organic solvent not containing active hydrogen in the molecule, a polyol and / or a polyamine, A polyisocyanate and optionally a low molecular diol or low molecular diamine as a chain extender, and the equivalent ratio of isocyanate group to active hydrogen-containing functional group is usually 1.0, a one-shot method, or By a multistage method, a polyurethane resin containing a polysiloxane group can be obtained by reacting usually at 20 to 150 ° C., preferably 60 to 110 ° C. until almost no isocyanate groups are present.

  In addition, about the polyurethane resin containing a polysiloxane group, you may synthesize | combine without a solvent or may synthesize | combine using an organic solvent. Preferable examples of the organic solvent include methyl ethyl ketone, methyl-n-propyl ketone, methyl isobutyl ketone, diethyl ketone, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, butyl acetate and cyclohexanone. Further, acetone, cyclohexane, tetrahydrofuran, dioxane, methanol, ethanol, isopropyl alcohol, butanol, toluene, xylene, dimethylformamide, dimethyl sulfoxide, perchlorethylene, trichloroethylene, methyl cellosolve, butyl cellosolve, cellosolve acetate and N-methyl-2- Pyrrolidone and the like can also be used.

  In the case of producing a polyurethane resin containing a polysiloxane group, the above-mentioned polysiloxane compound containing at least one active hydrogen group in the same molecule is 0.01 to 30% by mass, preferably 0.5%. -20% by weight, polyol and / or polyamine 20-90% by weight, preferably 30-80% by weight, chain extender 40-1% by weight, preferably 20-2% by weight (the total of these components is 100% by weight) The ratio of polyisocyanate is synthesized with NCO / OH≈1.0. In addition, when there are many polysiloxane compounds (when it exceeds 30 mass%), optical protective films will slip too much and it is impossible to pile up at the time of cutting storage, and it is used for quality process control by an unreacted polysiloxane component. Since the phenomenon of repelling ink occurs, it is not preferable. On the other hand, when the amount of the polysiloxane compound is small (less than 0.01% by mass), the slippage between the protective films for optics is insufficient, the cleaning performance of contaminants is insufficient, the solvent resistance and the humidity control of the outside air are not preferable. .

  The molecular weight of the polyurethane resin (B) containing a polysiloxane group used in the present invention is preferably in the range of 5,000 to 500,000 in terms of weight average molecular weight (measured by GPC, converted to standard polystyrene).

  The carbon nanotube used in the present invention is not particularly limited, and examples thereof include a material having a single-layer structure in which carbon hexagonal mesh surfaces are closed in a cylindrical shape or a multilayer structure in which cylindrical structures are arranged in a nested manner. The shape is a hollow cylinder having a diameter of 1 to 100 nm and a length of 1 to 50 μm. The method for producing the carbon nanotube is not particularly limited, and the carbon nanotube can be obtained by chemical vapor deposition, catalytic vapor deposition, chemical vapor deposition, arc discharge, laser evaporation, and the like. Either can be used in the present invention.

  The amount of the resin (A), the resin (B), and the carbon nanotube (D) used is 15% of the total amount (100% by mass) of (A), (B), and (D). -95 mass%, (B) is 60-5 mass%, and (D) is 25-0.1 mass%. If the amount of use of (A) exceeds 95% by mass, the working life of the paint and the adhesion of the surface protective layer to the base film are unfavorable, and if it is less than 15% by mass, the crosslinking density and solvent resistance decrease. This is not preferable. If the amount of (B) used exceeds 60% by mass, the protective films for optics will slip too much, and this will lead to poor ink suitability and a decrease in solvent resistance. It is not preferable because it is easily affected by deterioration of properties and environmental humidity. On the other hand, if the amount of (D) used exceeds 25% by mass, the solvent resistance and scratch properties are lowered and the paint becomes unstable, which is not preferred. This is not preferable because the antistatic performance is lowered.

  In the said polyisocyanate (C), the well-known thing used conventionally can be used and it does not specifically limit. For example, dimer of 2,4-toluylene diisocyanate, triphenylmethane triisocyanate, tris- (p-isocyanatephenyl) thiophosphite, polyfunctional aromatic isocyanate, polyfunctional aromatic aliphatic isocyanate, polyfunctional aliphatic Examples thereof include blocked polyisocyanates such as isocyanate, fatty acid-modified polyfunctional aliphatic isocyanate, and blocked polyfunctional aliphatic isocyanate, and polyisocyanate prepolymers. Of these, it is possible to use either an aromatic or aliphatic type, preferably a modified product such as diphenylmethane diisocyanate and tolylene diisocyanate for an aromatic type, hexamethylene diisocyanate and isophorone diisocyanate for an aliphatic type, and a molecule. A urethane prepolymer obtained by reacting a polyisocyanate multimer or an adduct with another compound, or a low molecular weight polyol or polyamine so as to be a terminal isocyanate is preferable. Etc. are also preferably used. These are exemplified below with structural formulas, but are not limited thereto.

  The use amount of these polyisocyanates (C) is 5 to 60 parts by mass, preferably 5 to 40 parts by mass with respect to 100 parts by mass in combination of the above (A), (B) and (D). If it exceeds 60 parts by mass, it is not preferable because the working life of the paint is reduced, and if it is less than 5 parts by mass, the crosslinking density of the surface protective layer is reduced, which is not preferable.

  In the coating material for forming the surface protective layer, if necessary, a curing catalyst, a reaction inhibitor and other additives can be appropriately used. Examples of the curing catalyst include dibutyltin laurate, dioctyltin laurate, stannous octoate, lead octylate, tetra-n-butyl titanate, and salts of organic or inorganic acids and organometallic derivatives such as triethylamine. And organic amines such as diazabicycloundecene catalysts. Examples of the reaction inhibitor include phosphoric acid, acetic acid, tartaric acid, phthalic acid, and formic acid ester.

  Further, for the purpose of imparting slipperiness and water resistance, for example, silicone oil and / or modified silicone oil (for example, polydimethylsiloxane, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane and aralkyl-modified polydimethylsiloxane), various types Additives such as waxes, acrylic polymers, long chain alkyl modified polymers, fluorine modified polymers and siloxane modified polymers can be added.

  Furthermore, for the purpose of use in combination with other antistatic agents, for example, polyvinyl alcohol, cation-modified polyvinyl alcohol, alkali metal salt-containing polyether, alkali metal salt-containing siloxane-modified polyether, alkali metal salt-containing ether polyurethane, polyamine, quaternary Organic conductive materials such as cation salt-containing acrylic resins, specially modified polyesters, special cationic resins, cellulose derivatives, polyacetylene, polyparaphenylene, polythiophene, polypyrrole, polyaniline and sulfonated polyaniline, carbon black, tin oxide, zinc oxide and Additives such as metal oxides such as titanium oxide and various metal alkoxides and conductive filler-containing polymers such as ITO powder can be added.

  Among the compounds, alkali metal salt-containing polyether, alkali metal salt-containing siloxane-modified polyether and alkali metal salt in the alkali metal salt-containing ether polyurethane, for example, lithium perchlorate, lithium bistrifluoromethanesulfonimide, Lithium borofluoride, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium pentafluoroethanesulfonate, lithium bispentafluoroethanesulfonimide, tetraethylammonium borofluoride, tetraethylammonium hexafluorophosphate and potassium bistrifluoromethanesulfone An imide etc. can be mentioned.

  When the surface protective layer is formed in the present invention, the resin (A) having an active hydrogen group in the molecule, the polyurethane resin (B) containing a polysiloxane group, the polyisocyanate (C), and the carbon nanotube A coating material for forming a surface protective layer containing (D) is used. The paint may be prepared without a solvent or may be prepared using an organic solvent. Preferable examples of the organic solvent include methyl ethyl ketone, methyl-n-propyl ketone, methyl isobutyl ketone, cyclohexanone, diethyl ketone, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate and butyl acetate. Acetone, cyclohexane, tetrahydrofuran, N-methyl-2-pyrrolidone, dioxane, toluene, xylene, dimethylformamide, dimethyl sulfoxide, perchlorethylene, trichloroethylene, methyl cellosolve, butyl cellosolve and cellosolve acetate can also be used. Although the solid content of the coating material prepared using the organic solvent is not particularly limited, it is preferably about 3 to 95% by mass.

  As the base film, for example, a film containing polyester, polyimide, polyethylene, polypropylene or the like as a component is used. Particularly preferred is a biaxially stretched polyethylene terephthalate film having an appropriate and necessary strength suitable for an optical protective film. The film thickness of the base film is preferably 20 to 100 μm, more preferably 25 to 40 μm. These base films may be subjected to corona treatment, antistatic treatment, easy adhesion treatment, and the like as necessary.

  The optical protective film of the present invention can be produced by a conventionally known method using the above-mentioned coating material for forming the surface protective layer, and the production method itself is not particularly limited. Moreover, as for materials other than surface protective layer forming materials, such as a base film and an adhesion layer forming material, all can use a well-known material and are not specifically limited. When forming the surface protective layer of the optical protective film of the present invention, the surface protective layer-forming coating material of the present invention is dried on the surface of the base film (the back surface is an adhesive layer) by a conventionally known method. A coating film is formed by coating so as to be about 0.01 to 1 μm.

  The surface protective layer thus obtained has a molecular structure due to the difference in surface energy between the resin (A) having an active hydrogen group in the molecule and the polysiloxane group in the polyurethane resin (B) containing a polysiloxane group. The active hydrogen group of the resin (A) having an active hydrogen group therein is hydrophilic and therefore is oriented on the surface of the base film to improve the adhesion of the surface protective layer to the base film. On the other hand, the component containing a polysiloxane group having a low surface energy is oriented on the opposite side (air side) of the base film, thereby imparting antifouling properties and moderate slipperiness.

  The polyisocyanate (C) forming the surface protective layer crosslinks the components in the material for forming the surface protective layer, so that it has solvent resistance and scratch resistance (up to surface hardness) that can withstand contamination removal of the surface protective layer. Further improvement can be achieved. As for the antistatic function, the carbon nanotube (D) is contained in the coating material for forming the surface protective layer, and the function is maintained.

Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples and comparative examples, but the present invention is not limited thereto. Moreover, in the following sentence, “part” indicates mass part, and “%” indicates mass%.
[Synthesis Examples 1 to 3]
A reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a reflux condenser was replaced with nitrogen gas, and then the lactone compound and siloxane compound shown in Table 1 were charged to a predetermined concentration and 100 ° C. under a nitrogen stream. The mixture was stirred until uniform. Subsequently, predetermined tetra-n-butyl titanate was added and reacted for 10 hours at a temperature of 180 ° C. under a nitrogen stream. As the reaction proceeds, the viscosity of the reaction product increases. Thereafter, the reaction was continued at 180 ° C. under a reduced pressure of 5 mmHg for 1 hour to complete the reaction, and the non-reactive siloxane compound and unreacted substances contained in the starting siloxane compound were completely removed. Table 1 shows the composition and properties of the obtained polycaprolactone-modified polysiloxane compound.

The siloxane compound (a) in Table 1 has the following structure.

[Synthesis Examples 4 to 7]
After replacing the reaction vessel equipped with a stirrer, reflux condenser, thermometer, nitrogen blowing tube and manhole with nitrogen gas, polycaprolactone-modified polysiloxane compound having a hydroxyl group of Synthesis Examples 1 to 3, polyol compound, chain extender compound And a predetermined amount of the solvent were added and dissolved uniformly, and the solution concentration was adjusted to 30%. Subsequently, a predetermined amount of diisocyanate compound (equal mole to 1 mole of active hydrogen groups) is added and the reaction is carried out at 80 ° C., and the reaction is continued until no absorption due to 2,270 cm ⁻¹ free isocyanate groups is observed in the infrared absorption spectrum. Went. Table 2 shows the raw material composition, properties and physical properties of the resulting siloxane-containing polyurethane resin.

PCD: polycarbonate diol (manufactured by Daicel Chemical Industries, trade name CD-220, average molecular weight 2,000)
1,3-BD: 1,3-butanediol HDI: hexamethylene diisocyanate MEK: methyl ethyl ketone

[Examples 1-4, Comparative Examples 1-4]
The paints for forming the surface protective layer of the present invention and comparative examples (solid content 5%) were prepared according to the compositions shown in Tables 3 and 4.

Aging condition: 40 ° C., 2 days EVOH; ethylene vinyl alcohol, trade name: F104 (ethylene copolymerization ratio = 32 mol%, melt index = 4.5 g / min .; 190 ° C., 2,160 g, Kuraray Co., Ltd.) Made)
-PVA; partially saponified polyvinyl alcohol, trade name: PVA-217 (degree of saponification = 87-89, degree of polymerization = 1,700, manufactured by Kuraray Co., Ltd.)
YP-50S; phenoxy resin, trade name: phenototo YP-50S (weight average molecular weight = 40,000, manufactured by Toto Kasei Kogyo Co., Ltd.)
BL-S; butyral group / acetyl group-containing polyvinyl alcohol copolymer, trade name: BL-S (hydroxyl group = 22 mol%, acetyl group = 3 to 5 mol%, butyral degree = 70 mol% or less, Sekisui Chemical Co., Ltd. ) Made)
-PHDI; HDI biuret type, trade name: Duranate 24A-100 (manufactured by Asahi Kasei Chemicals Corporation)
・ CNT; Carbon nanotube ・ DMF; Dimethylformamide ・ Anone; Cyclohexanone

  The paint used for the optical protective film of the present invention is a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, and a carbon nanotube (D) dissolved in an organic solvent. Or create it in a distributed manner. Any known dispersion method may be used as the dissolution or dispersion method, and is not particularly limited. For example, a paint is prepared by dispersing with a ball mill, basket mill, sand mill, roll mill, attritor, wet jet mill, dissolver, paint shaker, extrusion mixer, homogenizer, ultrasonic disperser or the like. After preparing this coating material, a polyisocyanate-based crosslinking agent is added and used as a coating for forming a surface protective layer.

  Using each paint obtained in each Example and Comparative Example, it was applied to the surface of a 38 μm thick polyethylene terephthalate (PET) film (manufactured by Toray) by gravure printing so that the thickness after drying would be 0.5 μm. After that, the solvent was dried in a dryer. When the paints of Examples 1 to 4 and Comparative Examples 1, 2, and 4 were used, after coating and drying, they were aged in an oven at 40 ° C. for 48 hours to form a surface protective layer. Since Comparative Example 3 did not use PHDI, the test was performed using a solvent dried without aging.

  Next, an adhesive composition was prepared with the following formulation. An adhesive layer was formed on the back surface of each PET film on which the surface protective layer had been formed by applying a gravure roll so that the thickness after drying was 25 μm, and optical protective films of Examples and Comparative Examples were obtained.

[Adhesive composition]
・ SK Seikadyne 1491H (manufactured by Soken Chemical Co., Ltd.) 100 parts ・ Curing agent L-45 (manufactured by Soken Chemical Co., Ltd.) 0.9 parts

[Test example]
The performances of the coating films of the surface protective layers and the protective films for optics of the Examples and Comparative Examples obtained above were tested for the following items, and the results shown in Table 5 were obtained.
<Surface resistance value>
The antistatic property of the optical protective film is measured using MCP-HT450 manufactured by Mitsubishi Chemical Corporation. The measurement conditions were a temperature of 23 ° C., a humidity of 65% RH, an applied voltage of 100 V, and 30 seconds. In order to exhibit the antistatic effect, 1 × 10 ¹⁰ Ω / cm ² or less is desirable.

<Transparency>
Using a direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd., the haze value of the protective film for optics was measured.
Haze value = Measured value−Haze value of substrate ○: Haze value is less than 5.0 Δ: Haze value is 5.0 or more and less than 10.0 ×: Haze value is 10.0 or more

<Ethyl acetate resistance>
1 g of ethyl acetate was hung on the surface of the optical protective film, and the appearance of the coating film of the surface protective layer when rubbed with a load of 50 g / cm ² was observed.
○: There is no change in the coating film appearance of the surface protection layer △: The coating film appearance of the surface protection layer is slightly changed ×: The coating film appearance of the surface protection layer is changed

<Easy to clean>
1 g of the pressure-sensitive adhesive composition (SK Seikadyne 1491H (manufactured by Soken Chemical Co., Ltd.) / Curing agent L-45 (manufactured by Soken Chemical Co., Ltd.) = 100 / 0.9) was rubbed against the coating film of the surface protective layer, and Kimwipe The ease of cleaning at the time of wiping was confirmed with dry wiping or using ethyl acetate.
○: Adhesive deposits can be easily washed (dry wipe)
Δ: Adhesive deposits can be washed (using ethyl acetate)
×: Adhesive deposits cannot be washed

<Scratch resistance>
The coating film of the surface protective layer of the optical protective film was rubbed with Scotch Bright (manufactured by Sumitomo 3M Co., Ltd.) under a load of about 10 g / cm ² , and the surface was visually checked for scratches.
○: 0 or more and less than 5 scratches that can be confirmed Δ: 5 or more and less than 10 scratches that can be confirmed ×: 10 or more scratches that can be confirmed

<Adhesion>
The adhesion between the coating film of the surface protective layer of the protective film for optics and the substrate PET film was measured by a cross cut test (cellophane tape peeling cross-cut method).
◎: Unpeeled squares are 95% or more ○: Unpeeled squares are less than 95% 70% or more △: Unpeeled squares are less than 70% 40% or more X: Unpeeled squares are less than 40%

<Slipperiness>
The dynamic friction coefficient of the optical protective film is measured using HEIDON-14DR manufactured by Shinto Kagaku Co., Ltd. The measurement conditions were a temperature of 23 ° C., a humidity of 65% RH, and an average value of 5 measurements. The dynamic friction coefficient is preferably in the range of 0.18 to 0.28.

<Printability>
Magic Ink No. manufactured by Teranishi Chemical Industry Co., Ltd. 500 was written on the coating surface of the surface protective layer, and the ink writing situation was observed.
○: The writing status of magic ink is good. △: There is a slight ink repellency, but there is no problem. ×: The ink cannot be repelled and written.

As described above, according to the present invention, in addition to antistatic properties, scratch resistance (scratch properties), and easy cleaning of contaminants (solvent resistance is required for cleaning with an organic solvent), printability (process) An optical protective film having the suitability of the printer ink used for management), adhesion to the substrate, transparency, moderate slipperiness, and the like can be obtained. Also provided is an optical protective film capable of a one-coat system having a surface protection function and an antistatic function.

Claims (7)

In the optical protective film comprising a base film, an adhesive layer provided on one side of the base film, and an antistatic surface protective layer provided on the other side of the base film, the antistatic property described above The surface protective layer comprises a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, a polyisocyanate (C), and a carbon nanotube (D) as a film forming component. A coat is formed with one coat,
The polyurethane resin (B) containing the polysiloxane group is a polysiloxane compound having hydroxyl groups at both ends, or a compound obtained by copolymerizing a siloxane with a polysiloxane compound having at least one active hydrogen group in the molecule. And a polyurethane resin obtained by reacting a polyisocyanate with a polyol or a polyamine.   Resin (A) having an active hydrogen group in the molecule is polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl Alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin The optical protective film according to claim 1, which is at least one selected from alkyd resins, phenol resins, polyethers, polyesters, celluloses, chitosan, and urethane resins.   The optical protective film according to claim 1, wherein the polyurethane resin (B) containing the polysiloxane group has a weight average molecular weight of 5,000 to 500,000. The optical protective film according to claim 1, wherein the surface resistance value is 10 ¹⁰ Ω / cm ² or less. A paint for forming an antistatic surface protective layer in the optical protective film according to claim 1, wherein the resin (A) has an active hydrogen group in the molecule and a polyurethane resin containing a polysiloxane group ( B) and carbon nanotubes (D) are dissolved or dispersed in an organic solvent, and polyisocyanate (C) is added before use, or stabilized polyisocyanate (C) is contained. A polyurethane resin (B) containing a polysiloxane group is a polysiloxane compound having hydroxyl groups at both ends, or a compound in which a polysiloxane compound having at least one active hydrogen group in the molecule and a lactone are copolymerized; It is a polyurethane resin obtained by reacting polyisocyanate with polyol or polyamine A surface protective layer-forming coating material.   The paint according to claim 5, wherein the resin (A) is an ethylene-vinyl alcohol copolymer, a partially saponified polyvinyl alcohol, or a phenoxy resin.   The resin (A) is 15 to 95% by mass of the total amount (100% by mass) of the resin (A), the resin (B) and the carbon nanotube (D), and the resin (B) The coating material according to claim 5, wherein the content is 60 to 5 mass% and the carbon nanotube (D) is 25 to 0.1 mass%.