JP2007108362A - Optical protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical protective film having antistatic property, scratching preventiveness, suitability to simple cleaning to remove contaminants, printability, adhesion to a base material, tansparency, and moderate lubricity. <P>SOLUTION: The optical protective film comprises a base film, an adhesive layer provided on one surface of the base film and an antistatic surface protective layer provided on another surface of the base film, wherein the antistatic surface preventive layer is formed using a siloxane copolymer (A), a carbon nanotube (B), and a polyisocyante (C) as coating film forming components. <P>COPYRIGHT: (C)2007,JPO&INPIT

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, adhesive layer and antistatic layer. The adhesive layer uses an adhesive with little adhesive residue, and the antistatic layer has an antistatic function. Has been. 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.

  In addition, the surface protective layer on 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 siloxane acrylate is applied to the other side of the base film that has undergone 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 production method, there is also a demand for changing the configuration system to a one-coat system (antistatic surface protective layer / base film).

  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. 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 An optical protective film, wherein the surface protective layer is formed using a siloxane copolymer (A), a carbon nanotube (B), and a polyisocyanate (C) as a film-forming component.

2. 2. The optical protective film as described in 1 above, wherein the siloxane copolymer (A) is at least one selected from the following A-1 to A-9.
A-1: A siloxane-modified urethane resin obtained by reacting a resin having an active hydrogen group in the molecule, a polysiloxane compound having at least one active hydrogen group in the molecule, and a polyisocyanate,
A-2: a siloxane-modified acrylic resin containing at least a siloxane macromonomer ((meth) acrylic group-containing siloxane macromer) unit,
A-3: a siloxane-modified polyester resin obtained by a condensation reaction between a compound having an alkoxysilyl group or a silanol group and a hydroxyl group-containing polyester resin,
A-4: A siloxane-modified polyester resin obtained by reacting an epoxy group, a carboxyl group and / or a hydroxyl group-containing siloxane compound with a monomer compound used in the polyester resin,
A-5: A siloxane-modified polycarbonate resin obtained by reacting a phenol group-containing siloxane compound with a monomer compound used in the polycarbonate resin (a phenol resin having two or more phenolic hydroxyl groups in one molecule),
A-6: a siloxane-modified epoxy resin obtained by reacting an epoxy group-containing siloxane compound with an amine compound,
A-7: A siloxane-modified epoxy resin obtained by reacting an epoxy resin (an epoxy resin having at least two epoxy groups in one molecule) with an amino group-containing siloxane compound,
A-8: A siloxane-modified polyimide resin obtained by reacting an amino group-containing siloxane compound with tetracarboxylic dianhydride,
A-9: A siloxane-modified polyalkylene glycol obtained by reacting a hydroxyl group-containing siloxane compound with an alkylene oxide compound.

3. Resins having an active hydrogen group in the molecule are polyether diol, polyester diol, polycarbonate diol, 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 2. The above 1, which is at least one selected from fluorine-based resins, melamine resins, alkyd resins, phenol resins, celluloses and chitosan Protective film for optical.

4). 2. The optical protective film as described in 1 above, wherein the polysiloxane group component in the siloxane copolymer is 0.0001 to 30% by mass.
5. ^2. The optical protective film as described in 1 above, wherein the surface resistance value is 10 ¹⁰ Ω / cm ² or less.
6). 2. The optical protective film as described in 1 above, wherein the surface protective layer has a function of easily cleaning contaminants and preventing scratches.

7). A coating material for forming a surface protective layer, comprising a siloxane copolymer (A), a carbon nanotube (B), and a polyisocyanate (C) dissolved and dispersed in an organic solvent.
8). The siloxane copolymer (A) is 50 to 99.9% by mass of the total amount (100% by mass) of the siloxane copolymer (A) and the carbon nanotube (B), and the carbon nanotube (B) is 50%. 8. The paint according to 7 above, which is ˜0.1% by mass.
9. 8. The coating material according to 7 above, further comprising adding a polyisocyanate before use or containing a stabilized polyisocyanate.

  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, An optical protective film excellent in printability, adhesion to a substrate film, transparency, and appropriate slipperiness can be obtained.

  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. An optical protective film comprising a protective surface protective layer, wherein the antistatic surface protective layer is formed of a siloxane copolymer, a carbon nanotube, and a polyisocyanate as film-forming components, so that the optical film has an excellent function. It was found that a protective film was obtained.

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 side of the base film, and an antistatic surface protective layer provided on the other side of the base film. Yes. That is, the structure on the surface protective layer side of the protective film for optics is characterized by the structure of a one-coat system such as an antistatic surface protective layer / base film, and the structure of the conventional three-coat system (surface protective layer) / Water resistant layer / antistatic layer / base film) or a 2-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 antistatic surface protective layer (hereinafter simply referred to as “surface protective layer”) will be described in detail.
The surface protective layer is formed by using the siloxane copolymer (A), the carbon nanotube (B), and the polyisocyanate (C) as film-forming components, and these are dissolved or dispersed in a solvent or the like, or are not present. It is preferable to apply and dry on a base film as a coating material for forming a surface protective layer with a solvent to form a surface protective layer.

As said siloxane copolymer (A), the said siloxane copolymer (A-1)-siloxane copolymer (A-9) are mentioned.
Siloxane copolymer (A-1): obtained by reacting a resin having an active hydrogen group in the molecule, a polysiloxane compound having at least one active hydrogen group in the molecule, and a polyisocyanate. When these materials are reacted, they may be reacted all at once, or after a polysiloxane compound having at least one active hydrogen group in the molecule and a polyisocyanate are reacted first, Although it may be reacted with a resin having an active hydrogen group, the latter reaction method is more preferred.

  Examples of the resin having an active hydrogen group in the molecule include polyether diol, polyester diol, polycarbonate diol, 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 Examples include ester resins, fluorine resins, melamine resins, alkyd resins, phenol resins, celluloses, and chitosan. Of these, ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol and phenoxy resin are particularly preferable.

Examples of the active hydrogen group in the resin having an active hydrogen group in the molecule include a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NRH (R: hydrocarbon group), —NH _2, etc.). And a thiol group (—SH), among which a hydroxyl group and an amino group are preferably used. When the resin has an active hydrogen group in the molecule, the active hydrogen group can be used for the reaction as it is, but when the resin does not have an active hydrogen group in the molecule, modification, etc. It can be used after being treated to give an active hydrogen group.

  As the polysiloxane compound having at least one active hydrogen group in the molecule used in the present invention, for example, the following compounds are preferably used (in this, modified using active hydrogen groups) An epoxy-modified polysiloxane 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 above epoxy-modified polysiloxane compound can be used by reacting with a polyol, polyamide, polycarboxylic acid or the like to have terminal active hydrogen.

(3) Alcohol-modified polysiloxane compound

(4) Mercapto-modified polysiloxane compound

  The polysiloxane compounds having an active hydrogen group in the molecule 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.

  As said polyisocyanate which can react with the said polysiloxane compound, what is used for manufacture of a conventionally well-known polyurethane can be used, and it does not specifically limit. 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), durylene diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), 1,5 Aromatic diisocyanates such as 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 particular, diisocyanate compounds having a difference in reaction rate between the primary reaction and the secondary reaction in the diisocyanate are preferable. Examples of such a compound include isophorone diisocyanate. Furthermore, a combination with a catalyst in which a difference in reaction rate between the primary reaction and the secondary reaction is remarkably shown by the reaction catalyst effect is more preferable.

  A method for producing a polysiloxane copolymer (A-1), in which a resin having an active hydrogen group in the molecule, a polysiloxane compound having at least one active hydrogen group in the molecule, and a polyisocyanate compound are reacted. Is not particularly limited, and a method similar to a conventionally known polyurethane production method can be used. For example, in the presence or absence of an organic solvent containing no active hydrogen in the molecule, first, equimolar amounts of a siloxane compound having at least one active hydrogen group in the molecule and a bifunctional diisocyanate compound are used. A compound having a polysiloxane group and a terminal isocyanate group in the same molecule is produced by reacting with a number. Next, a resin having an active hydrogen group and a polysiloxane group in the same molecule is produced by reacting this compound with an active hydrogen group in the resin having an active hydrogen group in the molecule. The reaction temperature is usually 20 to 150 ° C., preferably 60 to 110 ° C., and finally the reaction is completed until almost no isocyanate groups are present.

  In the present invention, the polysiloxane copolymer (A-1) may be synthesized without a solvent or may be produced 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, and butyl acetate. Acetone, cyclohexane, tetrahydrofuran, dioxane, methanol, ethanol, isopropyl alcohol, butanol, toluene, xylene, dimethylformamide, dimethyl sulfoxide, perchlorethylene, trichloroethylene, methyl cellosolve, butyl cellosolve, cellosolve acetate, and the like.

Siloxane copolymer (A-2): A siloxane-modified acrylic resin containing at least a siloxane macromonomer ((meth) acrylic group-containing siloxane macromer) unit. As the polysiloxane compound having at least one (meth) acryl group in the molecule used here, for example, the following compounds are preferably used.

  Examples of the acrylic monomer compound copolymerized with the siloxane macromonomer include methacrylic acid such as methacrylic acid, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, benzyl methacrylate, trimethylsilylpropyl methacrylate, and the like. Ester monomers, alkyl acrylates having 1 to 12 carbon atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and styrene, α- Examples thereof include aromatic vinyl monomers such as methylstyrene, and vinyl cyanide monomers such as acrylonitrile and methacrylonitrile. These may be used alone or in combination of two or more. The production method for reacting the siloxane macromonomer ((meth) acrylic group-containing siloxane macromer) with the acrylic monomer is not particularly limited, and a method similar to a conventionally known method for producing an acrylic resin can be used.

  Siloxane copolymer (A-3): A siloxane-modified polyester resin obtained by a reaction between a compound having an alkoxysilyl group or silanol group and a hydroxyl group-containing polyester resin. The siloxane copolymer (A-3) is obtained by subjecting a hydroxyl group of a saturated polyester and / or unsaturated polyester generally used to a condensation reaction of a silanol group or an alkoxide group of a siloxane compound using an organic titanate catalyst. .

  Siloxane copolymer (A-4): A siloxane-modified polyester resin obtained by reacting an epoxy group, carboxyl group and / or hydroxyl group-containing siloxane compound with a monomer compound used in the production of a polyester resin. As the modified siloxane compound used for the production of the copolymer, the aforementioned epoxy group, carboxyl group and / or hydroxyl group-containing siloxane compound is preferable.

  Examples of the monomer compound used for the production of the siloxane copolymer (A-4) include polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrachlorophthalic acid, Examples include acids, malonic acid, succinic acid, adipic acid, sebacic acid, cyclopentanedicarboxylic acid, trimellitic acid, pyromellitic acid and the like. On the other hand, as polyhydric alcohol, ethylene glycol, propylene glycol, butanediol, hexamethylene glycol, hydrogenated bisphenol A, neopentyl glycol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, etc. Is mentioned. A method for producing the siloxane-modified polyester resin of the siloxane copolymer (A-4) using such a monomer compound is not particularly limited, and a method similar to a conventionally known method for producing a polyester resin can be used.

Siloxane copolymer (A-5): A siloxane-modified polycarbonate resin obtained by reacting a phenol group-containing siloxane compound with a monomer compound used in the polycarbonate resin (a phenol resin having two or more phenolic hydroxyl groups in one molecule). . The general phenol group-containing siloxane compound used here is shown as follows.

  As the phenol resin having two or more phenolic hydroxyl groups in one molecule used above, a phenol resin having two or more phenolic hydroxyl groups in one molecule can be preferably used. Biphenyl phenols such as A type and bisphenol F type, novolaks such as phenol novolak and cresol novolak, triphenol alkane type resins such as triphenolmethane type and triphenol propane type, cyclopentadiene type phenol, and carbonic acid diester compound include diphenyl carbonate And dialkyl carbonates such as dimethyl carbonate and diethyl carbonate. These can be used alone or in admixture of two or more. For the siloxane copolymer (A-5), a method similar to a conventionally known method for producing a polycarbonate resin can be used.

Siloxane copolymer (A-6): A siloxane-modified epoxy resin obtained by reacting an epoxy group-containing siloxane compound with an amine compound.
Siloxane copolymer (A-7): A siloxane-modified epoxy resin obtained by reacting an epoxy resin (an epoxy resin having at least two epoxy groups in one molecule) with an amino group-containing siloxane compound.

  Examples of the epoxy group-containing siloxane compound and the amino group-containing siloxane compound used for the production of the siloxane copolymer (A-6) and the siloxane copolymer (A-7) may be those described above. Examples of the epoxy resin having at least two epoxy groups in one molecule used above include glycidyl ether type epoxy resins such as bisphenol A type, phenol novolak type, and cresol novolak type, and glycidyl ester type epoxy resins. , Known alicyclic epoxy resins, halogenated epoxy resins and the like, and epoxy group-containing siloxane compounds such as aliphatic amines such as diethylenetriamine, aromatic amines such as metaphenylenediamine, phthalic anhydride and maleic anhydride, etc. Curing with organic carboxylic acid anhydride, glycidyl ether type epoxy resin such as bisphenol A type, phenol novolak type, cresol novolak type, glycidyl ester type epoxy resin, alicyclic epoxy resin, halogenated epoxy And known ones such as butter, and the like method of reacting an amino group-containing siloxane compound. In addition, commercially available siloxane-modified epoxy resins can also be used.

  Siloxane copolymer (A-8): A siloxane-modified polyimide resin obtained by reacting an amino group-containing siloxane compound with tetracarboxylic dianhydride. Examples of the amino group-containing siloxane compound used here may be those shown above, and it is desirable to use a reaction of a known tetracarboxylic dianhydride, a diamine compound and an amino group-containing siloxane compound.

  Siloxane copolymer (A-9): A siloxane-modified polyalkylene glycol obtained by reacting a hydroxyl group-containing siloxane compound with an alkylene oxide compound. As the hydroxyl group-containing siloxane compound, the above hydroxyl group-containing siloxane compound is used, and in order to obtain the molecular chain of the oxyalkylene polymer, alkylene oxides, specifically, ethylene oxide, propylene oxide, α-butylene oxide, β- Examples include butylene oxide, hexene oxide, cyclohexene oxide, styrene oxide, α-methylstyrene oxide, and the like, and can be obtained by ring-opening polymerization of alkylene oxide in the presence of various catalysts. Examples of the polymerization catalyst include alkali catalysts such as KOH and NaOH.

  The amount of the polysiloxane group in the polysiloxane copolymer is 0.0001 to 30% by mass, preferably 0.01 to 20% by mass, based on the entire copolymer. When there are many polysiloxane groups (over 30% by mass), the resulting optical protective film is too slippery to be stacked during cutting and storage, and used for quality process control due to the presence of unreacted polysiloxane compounds. This is not preferable because a phenomenon of repelling ink occurs. On the other hand, when the polysiloxane group is small (less than 0.0001% by mass), the resulting optical protective film is insufficiently slippery, lacks the ability to easily clean contaminants, and makes it impossible to control the solvent resistance and humidity of the outside air. Absent.

  The carbon nanotube (B) 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. Can be mentioned. 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.

  By using the hollow cylindrical carbon nanotube as described above, the transparency and film forming property of the coating film are improved. In addition, the antistatic protective layer using carbon nanotubes having ultrafine and high conductivity can exhibit the antistatic effect with a small content compared to the conventional antistatic protective layer using carbon black.

  The amount of the siloxane copolymer (A) and the carbon nanotube (B) used is (A) 50 to 99.9% by mass, preferably 70 to 100% by mass in total of (A) and (B). It is -99 mass%, (B) is 50-0.1 mass%, Preferably it is 30-1 mass%. If the amount of (A) used exceeds 99.9% by mass, the antistatic function cannot be obtained, and it is not preferable, and if it is less than 50% by mass, the solution stability and scratch resistance are deteriorated.

  As the polyisocyanate (C) for forming the surface protective layer, known ones conventionally used can be used and are not particularly limited. 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 amount of the polyisocyanate (C) used is 5 to 100 parts by mass, preferably 5 to 55 parts by mass, based on 100 parts by mass of the siloxane copolymer (A) and the carbon nanotube (B). . If the amount of (C) used exceeds 100 parts by mass, it is not preferable because the usable time 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.

  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.

  Furthermore, for the purpose of imparting slipperiness and water resistance, for example, siloxane oil and / or modified siloxane oil (for example, polydimethylsiloxane, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane and aralkyl-modified polydimethylsiloxane), various types Additives such as waxes, 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.

  In the present invention, when the surface protective layer is formed, the siloxane copolymer (A) having an active hydrogen group and a polysiloxane group in the molecule, the carbon nanotube (B), and the polyisocyanate (C) are added. Use the coating for forming the surface protective layer. 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, diethyl ketone, cyclohexanone, 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 thickness of a base film becomes like this. Preferably it is 20-100 micrometers, More preferably, it is 25-40 micrometers. 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. Is applied to form a film.

  The surface protective layer obtained in this manner is in contact with the base film of the surface protective layer due to the difference in surface energy between the siloxane copolymer (A) and the carbon nanotube (B). The anti-contamination property and moderate slipperiness are imparted by improving the properties and aligning the surface of the siloxane component. The antistatic function is maintained by incorporating carbon nanotubes in the surface protective layer-forming coating material.

  Since the polyisocyanate (C) forming the surface protective layer crosslinks the components in the material for forming the surface protective layer, 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.

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 1-2]
A reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a reflux condenser is replaced with nitrogen gas, and then a predetermined amount of a polyisocyanate compound, a reaction catalyst and an organic solvent (solid content = 30%) is charged. Warm to ° C. Subsequently, a predetermined polysiloxane compound was added to a predetermined concentration and stirred at 80 ° C. in a nitrogen stream until uniform. Table 1 shows the composition and properties of the obtained oligomer having a polysiloxane group and an isocyanate group.

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

[Synthesis Examples 3 to 6]
A reaction vessel equipped with a stirrer, reflux condenser, thermometer, nitrogen blowing tube and manhole was replaced with nitrogen gas, and then a predetermined amount of a resin (base resin) having an active hydrogen group in the molecule and a solvent was added, To dissolve the resin. Subsequently, a predetermined amount of the oligomer having the polysiloxane group and the isocyanate group prepared above was added, and the reaction was performed at 90 ° C. until the absorption by the free isocyanate group of 2,270 cm ⁻¹ was not observed in the infrared absorption spectrum. Went. Table 2 shows the raw material composition and properties of a resin having an active hydrogen group and a polysiloxane group in the molecule.

Si-NCO (H); oligomer having polysiloxane group and isocyanate group EVOH; ethylene vinyl alcohol, trade name: F104 (ethylene copolymerization ratio = 32 mol%, melt index = 4.5 g / min .; 190 ° C., 2,160g, manufactured by Kuraray Co., Ltd.)
-PVA; partially saponified polyvinyl alcohol, trade name: PVA-217 (degree of saponification = 87-89, degree of polymerization = 1700, manufactured by Kuraray Co., Ltd.)
YP-50S; phenoxy resin, trade name: phenototoy YP-50S (weight average molecular weight = 40,000, manufactured by Toto Kasei Kogyo Co., Ltd.)
BL-1; butyral group / acetyl group-containing polyvinyl alcohol copolymer, trade name: BL-1 (hydroxyl group = 36 mol%, acetyl group = 3 mol% or less, butyral degree = 63 mol%, manufactured by Sekisui Chemical Co., Ltd.) )
・ MEK; Methyl ethyl ketone ・ DMF; Dimethylformamide

[Synthesis Example 7]
After replacing the reactor equipped with a stirrer, reflux condenser, thermometer, nitrogen blowing tube and manhole with nitrogen gas, 70 g of ethyl methacrylate, 2 g of 2-hydroxyethyl methacrylate, 18 g of n-butyl acrylate and siloxane macromonomer ((Meth) acrylic group-containing siloxane macromer) (b-1) 10 g, a mixed solvent of toluene / methyl ethyl ketone = 1/1 was added so that the non-volatile content was 30%, and azobisisobutyronitrile was added as an initiator. 0 g was added, heated to 70 ° C. while bubbling nitrogen, and stirred for 8 hours to synthesize a siloxane-modified acrylic resin.

[Synthesis Example 8]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube and a manhole was replaced with nitrogen gas, and then 5 g of a hydroxyl group-containing siloxane compound (a-2) and 95 g of butanediol were charged. After adding an amount of isophthalic acid and injecting nitrogen gas, heating to 140 ° C and reacting for 1 hour, adding 0.1% tetrabutyl titanate as a transesterification catalyst, heating at 190 ° C and reacting for 5 hours And then reacted at 190 ° C. and 15 mm / Hg or less for 2 hours to obtain a siloxane-modified polyester resin.

[Synthesis Example 9]
After replacing a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube and a manhole with nitrogen gas, 71 g of pyromellitic dianhydride and a predetermined N-methyl-2-containing compound having a nonvolatile content of 10% Pyrrolidone was added and dissolved by stirring. Next, 29 g of amino group-containing siloxane compound (c-1) was added dropwise over 1 hour and reacted at room temperature for 2 hours. Subsequently, 57 g of 4,4′-oxydianiline was added and reacted at room temperature for 2 hours to obtain a siloxane-modified polyimide precursor resin.

[Paint preparation 1]
・ X-22-4272 ^{* 1} 10.0 parts ・ ADEKA POLYOL G-1500 ^{* 2} 90.0 parts ・ MEK 400.0 parts * 1: manufactured by Shin-Etsu Chemical Co., Ltd., polyether group-containing siloxane compound, hydroxyl value 48
* 2: Polyether polyol compound, hydroxyl value 110, manufactured by Asahi Denka Kogyo Co., Ltd.

[Paint preparation 2]
・ KF-105 ^{* 3} 10.0 parts ・ Epicoat 1001B80 ^{* 4} 90.0 parts ・ MEK 320.0 parts * 3: manufactured by Shin-Etsu Chemical Co., Ltd., epoxy group-containing siloxane compound, epoxy equivalent 450
* 4: Epoxy equivalent 475, manufactured by Japan Epoxy Resin Co., Ltd.

[Examples 1-9, Comparative Examples 1-2]
The surface protective layer-forming paints (solid content 5%) of Examples 1 to 9 and Comparative Examples 1 and 2 were prepared according to the compositions of Tables 3, 4, 5 and Table 6.

Aging condition: 40 ° C., 2 days PHDI: HDI biuret type, Duranate 24A-100 (manufactured by Asahi Kasei Chemicals Corporation)
· MEK; methyl ethyl ketone · DMF; dimethylformamide · CNT; carbon nanotubes · anone: cyclohexanone · NMP: N-methyl-2-pyrrolidone · PA: epicure 3080: manufactured by Japan Epoxy Resins Co., Ltd., modified aliphatic amine

  The paint used for the optical protective film of the present invention is prepared by dissolving or dispersing the siloxane copolymer (A) and the carbon nanotube (B) in an organic solvent. 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. A polyisocyanate-based crosslinking agent is added to this paint (Example 9 contains a modified aliphatic amine) and used as a paint 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 coating materials of Examples 1 to 9 and Comparative Example 2 were used, the surface protective layer was formed by aging in an oven at 40 ° C. for 48 hours after application and drying. Comparative Example 1 was evaluated by drying at 110 ° C. for 90 seconds without aging. Moreover, the coating material using the siloxane modified polyimide precursor of Example 7 was evaluated after heat treatment at 120 ° C. for 30 minutes.

  Next, an adhesive composition was prepared according to 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 performance 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 7 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 as follows: temperature 23 ° C., humidity 65% RH, applied voltage 100 V, 30 seconds. In order to exert the antistatic effect, 1 × 10 ¹¹ 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 appearance of the coating film of the surface protection layer. Δ: The appearance of the coating film of the surface protection layer is slightly changed. X: The appearance of the coating film of the surface protection layer is changed.

<Easy cleaning of contaminants>
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 during wiping was confirmed.
○: Adhesive deposits can be easily washed △: Adhesive deposits remain a little ×: 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 the 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) Printer ink used for management), optical protective film with adhesion to substrate, transparency and moderate slipperiness, etc. can be created, one coat that has both surface protection function and antistatic function An optical protective film capable of the system is provided.

Claims (9)

  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 An optical protective film, wherein the surface protective layer is formed using a siloxane copolymer (A), a carbon nanotube (B), and a polyisocyanate (C) as a film-forming component. The optical protective film according to claim 1, wherein the siloxane copolymer (A) is at least one selected from the following A-1 to A-9.
A-1: A siloxane-modified urethane resin obtained by reacting a resin having an active hydrogen group in the molecule, a polysiloxane compound having at least one active hydrogen group in the molecule, and a polyisocyanate,
A-2: a siloxane-modified acrylic resin containing at least a siloxane macromonomer ((meth) acrylic group-containing siloxane macromer) unit,
A-3: a siloxane-modified polyester resin obtained by a condensation reaction between a compound having an alkoxysilyl group or a silanol group and a hydroxyl group-containing polyester resin,
A-4: A siloxane-modified polyester resin obtained by reacting an epoxy group, a carboxyl group and / or a hydroxyl group-containing siloxane compound with a monomer compound used in the polyester resin,
A-5: A siloxane-modified polycarbonate resin obtained by reacting a phenol group-containing siloxane compound with a monomer compound used in the polycarbonate resin (a phenol resin having two or more phenolic hydroxyl groups in one molecule),
A-6: a siloxane-modified epoxy resin obtained by reacting an epoxy group-containing siloxane compound with an amine compound,
A-7: A siloxane-modified epoxy resin obtained by reacting an epoxy resin (an epoxy resin having at least two epoxy groups in one molecule) with an amino group-containing siloxane compound,
A-8: A siloxane-modified polyimide resin obtained by reacting an amino group-containing siloxane compound with tetracarboxylic dianhydride,
A-9: A siloxane-modified polyalkylene glycol obtained by reacting a hydroxyl group-containing siloxane compound with an alkylene oxide compound.   Resins having an active hydrogen group in the molecule are polyether diol, polyester diol, polycarbonate diol, 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 The fluorine resin, melamine resin, alkyd resin, phenol resin, celluloses and chitosan are at least one selected from the group consisting of Optical protective film of.   The protective film for optics according to claim 1, wherein the polysiloxane group component in the siloxane copolymer is 0.0001 to 30% by mass. The optical protective film according to claim 1, wherein the surface resistance value is 10 ¹⁰ Ω / cm ² or less.   The optical protective film according to claim 1, wherein the surface protective layer has a function of easily cleaning contaminants and preventing scratches.   A coating material for forming a surface protective layer, comprising a siloxane copolymer (A), a carbon nanotube (B), and a polyisocyanate (C) dissolved and dispersed in an organic solvent.   The siloxane copolymer (A) is 50 to 99.9% by mass of the total amount (100% by mass) of the siloxane copolymer (A) and the carbon nanotube (B), and the carbon nanotube (B) is 50%. The coating material according to claim 7, which has a content of ˜0.1% by mass. Furthermore, the polyisocyanate is added before use, or the coating material of Claim 7 containing the stabilized polyisocyanate.