JP2006175848A - Protection film for optical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection film for optical uses, having antistatic properties, scratch resistance, ready cleanability for pollutant, printability, good adhesion to a substrate film, transparency, a moderate slippage, etc. <P>SOLUTION: The protection film for optical uses consists of the substrate film, an adhesive layer arranged on one side of the substrate film, and an antistatic surface protective layer arranged on the other side of the substrate film, and the above surface protective layer is formed in such a manner that a resin (A) having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent (B), and a polyisocyanate (C) serve as a film forming component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 an antistatic function, a contaminant easy cleaning function, a scratch preventing function, and the like.

  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 a side to be bonded to the polarizing plate, and is composed of a separate film layer, an adhesive layer and an antistatic layer. The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive with little adhesive residue, and the antistatic layer has an antistatic function. An antistatic layer, a water resistant layer and a surface protective layer are formed on the other surface of the optical protective film. The function of the antistatic layer is as described above, and the function of the water resistant layer is to minimize the influence of the external environment (humidity) on the antistatic layer, and the surface protective layer has many functions. Yes.

  When manufacturing polarizing plates used for liquid crystal displays, etc., an optical protective film is bonded to the surface of the polarizing plate so that the polarizing plate is not soiled or scratched, and when used, the optical protective film is peeled off from the polarizing plate. To do.

  The reason for imparting an antistatic function to the adhesive layer side of the optical protective film is that when dust is attached to the polarizing plate due to static electricity generated in the process of manufacturing the polarizing plate, or when the optical protective film is peeled off from the polarizing plate. This is to prevent a defective product from occurring in the polarizing plate due to the generated static electricity.

  Further, the outer surface protective layer opposite to the adhesive layer of the optical protective film is provided with an antistatic function, an anti-scratch function, an easily-cleaning function for 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 laminated and stored, or when removing it during storage, etc., the polarizing plate is likely to be damaged. Is.

  Contaminant easy-cleaning function adheres when adhesive is attached to the protective layer when the polarizing plate and optical protective film are bonded together, or is cut according to the required specifications as a polarizing plate, and stacked and stored. This is because an 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. During such wiping, the protective film for optics is required to have a function of easily cleaning contaminants.

  As an example of production of an optical protective film having the above functions, an acrylic pressure-sensitive adhesive is applied to one side of a base film, and a silicone acrylate is applied to the other side of the base film that has been subjected to an antistatic treatment. Examples of the protective film adhesive sticking prevention by sticking out of the film and the function of easily cleaning contaminants (see Patent Document 1), and the surface protective layer was long-chain alkylated with polyvinyl alcohol or polyethyleneimine Examples have been proposed (see Patent Documents 2 and 3) in which a copolymer or the like is applied to prevent adhesion of the pressure-sensitive adhesive protruding from the cut surface to the surface of the optical protective film.

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

  However, the proposed protective film for optics 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. In addition, from the 3 coat system (surface protective layer / water resistant layer / antistatic layer / base film), which is the construction system of the current surface protective layer, to the 2 coat system (surface protective layer / antistatic layer / base film), Furthermore, for the purpose of simplifying the manufacturing method, there is a demand for a change in 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, the objective of this invention is providing the protective film for optics in which 1 coat system called the surface protective layer / base film which also has the antistatic function as a structure of a surface protective layer is possible.

  As a result of intensive studies to solve the above-mentioned problems, the inventors have made 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 the optical protective film comprising the protective surface protective layer, the surface protective layer is formed by forming a resin having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent, and a polyisocyanate as a film forming component. The present inventors have found that an optical protective film having an excellent function can be obtained, and have reached the present invention.

That is, the present invention has the following configuration.
1. 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 (hereinafter sometimes referred to simply as “surface protective layer”) In the optical protective film, the surface protective layer comprises a resin (A) having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent (B), and a polyisocyanate (C) as a film forming component. An optical protective film characterized by being formed.

2. The resin (A) is a 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. The protective film for optics as described in 2.
3. 2. The optical protective film as described in 1 above, wherein the resin (A) contains 0.0001 to 30% by mass of a polysiloxane group component in the resin.

4). A resin in which the resin (A) has a hydroxyl group, a carboxyl group, an amino group, a thiol group and / or an epoxy group in the main chain and / or side chain, and a polysiloxane compound having an amino group or a hydroxyl group in the molecule 2. The optical protective film as described in 1 above, which is a reaction product of polyisocyanate.
5. 2. The optical protective film as described in 1 above, wherein the antistatic agent (B) is at least one selected from a conductive polymer, an ion conductive polymer, a metal oxide, a metal alkoxide, and a conductive filler-containing polymer substance.

6). ^2. The optical protective film as described in 1 above, wherein the surface resistance value is 10 ⁵ to 10 ¹² Ω / cm ² .
7). 2. The optical protective film as described in 1 above, wherein the surface protective layer has a haze value of 0 to 1.2%.
8). 2. The optical protective film as described in 1 above, wherein the surface protective layer has a dynamic friction coefficient of 0.15 to 0.30.

9. A coating material for forming a surface protective layer, comprising a resin (A) having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent (B), and a polyisocyanate (C) dissolved in an organic solvent.
10. The resin (A) is 20 to 98% by mass of the total amount (100% by mass) of the resin (A) and the antistatic agent (B), and the antistatic agent (B) is 80 to 2% by mass. 10. The paint according to 9 above.
11. Furthermore, the coating material of said 9 which adds polyisocyanate before use or contains 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 a surface protective layer / base film, and is antistatic, scratch resistant, easily washed out of contaminants, and printable. An optical protective film excellent in adhesion to a substrate film, transparency, moderate slipperiness, and the like is provided.

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 comprising a structure of one coat system such as a 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 two-coat system construction (surface protective layer / antistatic layer / base film). That is, the surface protective layer of the protective film for optics of the present invention is a surface protective layer that is excellent in cost performance by reducing the number of coatings during production.

Next, the surface protective layer in the present invention will be described in detail.
The surface protective layer is formed using a resin (A) having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent (B), and a polyisocyanate (C) as a film forming component. It is preferable to dissolve and disperse the components in a solvent or the like, or to apply and dry as a surface protective layer-forming coating material on a base film without using a solvent to form a surface protective layer. The coating material for forming the surface protective layer in this case is a composition comprising the resin (A), the antistatic agent (B) and the polyisocyanate (C).

  As the resin (A), it is preferable to use a reaction product of 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. In reacting these components, all of these components may be reacted together, or a polysiloxane compound having at least one active hydrogen group in the molecule and a polyisocyanate are reacted first. The obtained reaction product may be reacted with a resin having an active hydrogen group in the molecule, but the resin (A) obtained by the latter reaction method is more preferred.

  Examples of the resin 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, phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin, alkyd resin, phenol resin, polyether , Polyesters, celluloses, chitosan and urethane resins. 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 is a divalent organic group), —NH. ₂ ), a thiol group (-SH) and / or an epoxy group, among which a hydroxyl group and an amino group are preferably used. In the resin having an active hydrogen group in the molecule, the active hydrogen group can be used for the reaction as it is, but when the resin molecule does not have an active hydrogen group, a treatment such as modification is performed. It can be used with an active hydrogen group.

  The polysiloxane group in the resin (A) will be described. In order to obtain the resin (A), it is preferable to use a polysiloxane compound having at least one active hydrogen group in the molecule and react with the resin having an active hydrogen group in the molecule via polyisocyanate. Therefore, the polysiloxane compound will be described. 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

(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 compound 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, aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate and 1,10-decamethylene diisocyanate, 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 primary reaction and secondary reaction in diisocyanate are preferable. Examples of such a compound include isophorone diisocyanate. Furthermore, a combination with a catalyst in which a reaction difference between the primary reaction and the secondary reaction is remarkably shown by the reaction catalyst effect is more preferable.

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

  The synthesis of the resin (A) may be performed without a solvent, or may be performed using an organic solvent. Preferable examples of the organic solvent used here 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.

  When the resin (A) is produced, the polysiloxane group in the resin (A) is contained in an amount of 0.0001 to 30% by mass, preferably 0.01 to 20% by mass, based on the entire resin (A). Is desirable. If there are many polysiloxane groups (exceeding 30% by mass), the optical protective film finally obtained is too slippery, and it is impossible to stack the optical protective film during cutting and storage. The presence of the siloxane compound in the surface protective layer is not preferable because a phenomenon of repelling ink used for quality process control of the optical protective film (or polarizing plate) may occur. On the other hand, if there are too few polysiloxane groups (less than 0.0001% by mass), the optical protective film is insufficiently slipped, the surface protective layer is not easily cleaned of contaminants, the solvent resistance of the surface protective layer and / or the outside air Humidity control is impossible, which is not preferable.

  A preferable material as the antistatic agent (B) which is a component forming the surface protective layer is at least one selected from a conductive polymer, an ion conductive polymer, a metal oxide, a metal alkoxide, and a conductive filler-containing polymer substance. Is mentioned. For example, polyvinyl alcohol, cation-modified polyvinyl alcohol, alkali metal salt-containing polyether (eg, Li salt of polyethylene oxide), alkali metal salt-containing ether polyurethane, polyamine, quaternary cation salt-containing acrylic resin, specially modified polyester, Special cationic resins, cellulose derivatives, polyacetylene, polyparaphenylene, polythiophene, polypyrrole, polyaniline, sulfonated polyaniline and other organic conductive materials, carbon black, tin oxide, zinc oxide, titanium oxide and other metal oxides, various metal alkoxides And one or more selected from conductive filler-containing polymers such as zinc antimonate sol and ITO powder.

  Among the above-mentioned compounds, examples of the alkali metal salt in the alkali metal salt-containing polyether and the alkali metal salt-containing ether polyurethane include lithium perchlorate, lithium bistrifluoromethanesulfonimide, lithium borofluoride, and hexafluorophosphoric acid. Examples include lithium, lithium trifluoromethanesulfonate, lithium pentafluoroethanesulfonate, lithium bispentafluoroethanesulfonimide, tetraethylammonium borofluoride, tetraethylammonium hexafluorophosphate, and potassium bistrifluoromethanesulfonimide.

Among the above compounds, examples of the ionic liquid compound in the alkali metal salt-containing polyether and the alkali metal salt-containing ether polyurethane include 1-ethyl-3-methylimidazolium ( Compounds such as alkyl imidazolium cation, alkyl pyridinium cation, alkyl ammonium cation, alkyl phosphonium cation and alkyl sulfonium cation represented by EMI) can be used. As the anionic component constituting the ionic liquid, AlCl ₄ ^- anion, the anion compounds such as fluorine-containing anions and nitric anion and acetate anion can be used.

  The ionic liquid used in the present invention is not particularly limited, and any known ionic liquid may be used. However, since it is difficult to purify impurities by complicated synthesis, both anionic compounds and cationic compounds are usually used. It is desirable to select organic ones.

  Among the compounds, for example, for polyamines, epomin (manufactured by Nippon Shokubai Co., Ltd.), polyallylamine (manufactured by Nitto Boseki Co., Ltd.), etc., for quaternary cationic polymers, for example, Elecondo (manufactured by Soken Chemical Co., Ltd.), Jurimer (Nippon Pure) Yakuhin Co., Ltd.), TK cation B (manufactured by Takamatsu Yushi Co., Ltd.), Texnol (manufactured by Nippon Emulsifier Co., Ltd.), NK polymer (manufactured by Shin-Nakamura Chemical Co., Ltd.), Efcol (manufactured by Matsumoto Yushi Co., Ltd.) and Sharol (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) However, in the metal alkoxy system, for example, various alkoxysilanes, various alumina sols, Colcoat (manufactured by Colcoat) and Cellnax (zinc antimonate sol, Nissan Chemical) are preferably used.

  The amount of the resin (A) and the antistatic agent (B) used is 20 to 98% by mass, preferably 50 to 95% by mass, when both are combined to 100% by mass, An antistatic agent (B) is 80-2 mass%, Preferably it is 50-5 mass%. When the amount of the resin (A) used exceeds 98% by mass, it is not preferable because a sufficient antistatic function cannot be obtained for the surface protective layer, and when the resin (A) is less than 20% by mass, the finally obtained surface It is not preferable because the solvent resistance and scratch resistance of the protective layer are lowered.

  As polyisocyanate (C) which forms a surface protective layer, the conventionally well-known thing 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 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 resin (A) and the antistatic agent (B). . When the amount of the polyisocyanate (C) used exceeds 100 parts by mass, it is not preferable because the usable time of the coating material used for forming the surface protective layer is decreased, and when the amount of the polyisocyanate (C) used is less than 5 parts by mass. Since the crosslink density of the surface protective layer to be formed is lowered, it is not preferable. When the polyisocyanate (C) has a free isocyanate group, the polyisocyanate (C) is preferably added to the paint containing the resin (A) and the antistatic agent (B) immediately before use of the paint. ) Is a stabilized polyisocyanate, it may be added to the paint before use.

  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 of the surface protective layer, for example, silicone oil and / or modified silicone oil (for example, polydimethylsiloxane, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, and aralkyl-modified polydimethylsiloxane). Etc.), additives such as various waxes, long chain alkyl-modified polymers, fluorine-modified polymers and siloxane-modified polymers can be added.

  In addition, when forming a surface protective layer in a base film, the coating material for surface protective layer formation which consists of said resin (A), antistatic agent (B), and polyisocyanate (C) 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, 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 a base film used for the optical protective film of the present invention, 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. The surface protective layer of the optical protective film of the present invention is prepared by applying the surface protective layer-forming coating composition of the present invention to the surface of the base film (back surface is an adhesive layer) by a conventionally known method. It is formed by coating so as to be about 01 to 1 μm.

  In the surface protective layer thus obtained, the active hydrogen group in the resin (A) is hydrophilic on the surface of the base film due to the difference in surface energy between the resin (A) and the antistatic agent (B). Many are oriented to improve the adhesion of the surface protective layer to the substrate film. On the other hand, many of the polysiloxane groups with low surface energy and the antistatic agent are oriented on the opposite side (air side) of the base film, giving the surface protective layer antistatic properties, antifouling properties and moderate slipperiness. Is done.

  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. With respect to the antistatic function, the function is maintained by incorporating an antistatic agent into the coating material for forming the surface protective layer.

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, thermometer, nitrogen gas inlet tube and reflux condenser is replaced with nitrogen gas, and then a predetermined amount of polyisocyanate compound, reaction catalyst, and organic solvent (solid content is 30%) are added. And warm to 60 ° 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 were added, and 60 ° C. To dissolve the resin. Subsequently a predetermined amount charged oligomers having a polysiloxane group and an isocyanate group prepared (Si-NCO) in the conducting reactions at 90 ° C., absorption by free isocyanate groups 2,270Cm ^-1 in the infrared absorption spectrum The reaction was continued until it was not observed. Table 2 shows the raw material composition and properties of the resin (A) thus obtained.

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 = 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-1; butyral group / acetyl group-containing polyvinyl alcohol copolymer (trade name: BL-1, hydroxyl group = 36 mol%, acetyl group = 3 mol% or less, degree of butyral = 63 mol%, manufactured by Sekisui Chemical Co., Ltd. )
・ MEK; Methyl ethyl ketone ・ DMF; Dimethylformamide

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

Aging condition: 40 ° C., 2 days PHDI: HDI biuret type (trade name: Duranate 24A-100, manufactured by Asahi Kasei Chemicals Corporation)
B-1; a compound obtained by subjecting a cationic type (quaternary ammonium salt) polyacrylate (trade name: Jurimer SP-50TF, manufactured by Nippon Pure Chemical Co., Ltd.) to DMF as a solvent)
B-2; a compound obtained by subjecting a cationic type (quaternary ammonium salt) polyacrylate (trade name: Electon PQ-50B, manufactured by Soken Chemical Co., Ltd.) to DMF as a solvent)
B-3; a compound obtained by subjecting a cationic polymer (trade name: Texnol CP-81, manufactured by Nippon Emulsifier Co., Ltd.) to DMF as a solvent)
B-4; a compound obtained by subjecting a cationic acrylic polymer (trade name: TK cation B, manufactured by Takamatsu Yushi Co., Ltd.) to DMF as a solvent)
MEK; methyl ethyl ketone, DMF, dimethylformamide, modified polymer (S), resin (A)

  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 1.0 μm. After that, the solvent was dried in a dryer. When the paints of Examples 1 to 4 and Comparative Example 1 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 2 was evaluated by drying at 110 ° C. for 90 seconds without aging.

  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 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, 10 ⁵ to 10 ¹² Ω / cm ² is preferable, and 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 base material If the haze value is 1.2% or less, the transparency is high and it is suitable for an optical protective film.

<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 surface protective coating film △: The appearance of the surface protective coating film is slightly changed ×: The appearance of the surface protective coating film 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 (Registered trademark) The ease of cleaning at the time of 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).

<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 0.15 to 0.30, and 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 resistance), and easy cleaning of contaminants (solvent resistance is required because it is washed with an organic solvent), printability is also achieved. (Printer ink used for process control), providing an optical protective film with adhesion to the substrate, transparency, and moderate slipperiness, and has both surface protection and antistatic functions An optical protective film capable of a one-coat system is provided.

Claims (11)

  In the optical protective film comprising a base film, an adhesive layer provided on one surface of the base film, and an antistatic surface protective layer provided on the other surface of the base film, the surface protective layer Is formed using a resin (A) having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent (B), and a polyisocyanate (C) as a film-forming component. .   The resin (A) is a resin obtained by reacting a resin having an active hydrogen group in a molecule, a polysiloxane compound having at least one active hydrogen group in the molecule, and a polyisocyanate. The protective film for optics according to 1.   The optical protective film according to claim 1, wherein the resin (A) contains 0.0001 to 30% by mass of a polysiloxane group component in the resin.   A resin in which the resin (A) has a hydroxyl group, a carboxyl group, an amino group, a thiol group and / or an epoxy group in the main chain and / or side chain, and a polysiloxane compound having an amino group or a hydroxyl group in the molecule The protective film for optics according to claim 1, which is a reaction product of polyisocyanate.   The optical protective film according to claim 1, wherein the antistatic agent (B) is at least one selected from a conductive polymer, an ion conductive polymer, a metal oxide, a metal alkoxide, and a conductive filler-containing polymer substance. The optical protective film according to claim 1, wherein the surface resistance value is 10 ⁵ to 10 ¹² Ω / cm ² .   The optical protective film according to claim 1, wherein the surface protective layer has a haze value of 0 to 1.2%.   The optical protective film according to claim 1, wherein the surface protective layer has a dynamic friction coefficient of 0.15 to 0.30.   A coating material for forming a surface protective layer, comprising a resin (A) having an active hydrogen group and a polysiloxane group in the molecule, an antistatic agent (B), and a polyisocyanate (C) dissolved in an organic solvent.   The resin (A) is 20 to 98% by mass of the total amount (100% by mass) of the resin (A) and the antistatic agent (B), and the antistatic agent (B) is 80 to 2% by mass. The paint according to claim 9.   Furthermore, the polyisocyanate is added before use, or the coating material of Claim 9 containing the stabilized polyisocyanate.