JP4866027B2 - Protective film for optics - Google Patents

Description

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

  A general optical protective film has a structure of surface protective layer / water resistant layer / antistatic layer / base film / antistatic layer / adhesive layer / separate film layer, and one side of the base film ( (Separate film layer side) is the side to be bonded to the polarizing plate, and consists of a separate film layer, an adhesive layer and an antistatic layer. The adhesive layer uses an adhesive with little adhesive residue, and the antistatic layer is antistatic. Functions are granted. The other surface of the optical protective film is composed of an antistatic layer, a water-resistant layer and a surface protective layer, and the antistatic layer is as described above, and the water-resistant layer affects the antistatic layer from the external environment (humidity). The surface protective layer has many functions.

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

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

  Further, the surface protective layer on the outer side of the other surface different from the adhesive layer of the optical protective film is provided with antistatic, scratch prevention, easy cleaning of contaminants, and the like. The necessity to give each is as follows. The antistatic function is as described above, and the scratch preventing function is cut and laminated according to the necessary specifications as a polarizing plate, especially when the polarizing plate and the optical protective film are bonded together with a roll. This is to cope with the problem that the polarizing plate is easily damaged when it is removed during storage or during storage.

  Contaminant easy-cleaning properties: Adhesive that adheres to the protective layer when the polarizing plate and optical protective film are bonded together, or adheres to the required specifications as a polarizing plate, and adheres when laminated and stored 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.

  Examples of the method for removing the adhesive attached to the optical protective film include a method of 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. Furthermore, in such operations, the protective layer side is wiped off with a solvent such as alcohol or ethyl acetate, so that the layers constituting the protective side (protective layer or antistatic layer) are solvent resistant (isopropyl alcohol, ethyl acetate, methyl ethyl ketone). , Toluene, etc.) are required to have no change in the appearance of the protective layer.

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

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

JP 2001-305346 A JP 11-256115 A JP 11-256116 A

  However, the proposed technique does not satisfy all the functions described above. In addition, there is a demand for a material for forming a surface protective layer for an optical protective film that has higher performance than before. Furthermore, the 3-coat system (surface protective layer / water resistant layer / antistatic layer / base film), which is a construction system of the current surface protective layer, is applied to the 2-coat system (surface protective layer / There is also a demand for a change in the configuration system to an antistatic layer / base film) or a reduction in thickness, and an improvement in necessary specifications is desired.

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 object of the present invention is to provide a two-coat system of surface protective layer / antistatic layer / base film as the structure of the surface protective layer, and an optical protective film further provided with a solvent resistance function for thinning. Is to provide.

The above object is achieved by the present invention having the following structure.
1. In the optical protective film comprising a base film, an adhesive layer provided on one side of the base film, and a surface protective layer provided on the other side of the base film via an antistatic layer, The surface protective layer is formed using a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, and a polyisocyanate (C) as a film-forming component, and the above antistatic An optical protective film, wherein the layer is formed using a resin (A) having an active hydrogen group in the molecule, a polyisocyanate (C), and an antistatic agent (D) as a film-forming component.

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

3. The polyurethane resin (B) containing a polysiloxane group is a polysiloxane compound having at least one active hydrogen group in the molecule and / or a compound obtained by copolymerizing the polysiloxane compound and a lactone, a polyisocyanate, and a polyol. Or the protective film for optics of said 1 which is a polyurethane resin obtained by making polyamine react, Comprising: The weight average molecular weight is 5,000-500,000.

4). 2. The optical protective film as described in 1 above, wherein the antistatic agent is a conductive filler.
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). The optical protective film according to any one of 1 to 5 above, wherein the resin (A) having an active hydrogen group in the molecule, the polyisocyanate (C), and the antistatic agent (D) are formed as a film forming component. An organic solvent comprising a resin (A) having an active hydrogen group in the molecule and a polyurethane resin (B) containing a polysiloxane group , which is a coating for forming a surface protective layer provided via an antistatic layer. In addition, the polyisocyanate (C) is added before use, or a stabilized polyisocyanate (C) is contained (except when an antistatic agent is included) . A coating material for forming a surface protective layer, comprising A), the resin (B), and the polyisocyanate (C) as film-forming components.
7). The resin (A) is an ethylene-vinyl alcohol copolymer, a partially saponified polyvinyl alcohol or a phenoxy resin, and the resin (B) contains a polysiloxane compound containing an amino group or a hydroxyl group in the molecule, and a lactone. The coating material for forming a surface protective layer as described in 6 above, which is a reaction product of a copolymer of the above, a polyisocyanate and a polyol.

8). The resin (A) is 20 to 80% by mass of the total amount (100% by mass) of the resin (A) and the resin (B), and the resin (B) is 80 to 20% by mass. The coating material for forming a surface protective layer according to the description .

  According to the present invention, the construction system of the surface protective layer of the optical protective film is a two-coat system such as surface protective layer / antistatic layer / base film, and has antistatic properties, scratch resistance, and easy cleaning of contaminants. Provided is an optical protective film having excellent properties (solvent resistance), printability, adhesion to a substrate film, transparency, and moderate slipperiness.

Next, the present invention will be described in more detail with reference to preferred embodiments.
The protective film for optics of the present invention includes a base film, an adhesive layer provided on one side of the base film, and a surface protective layer provided on the other side of the base film via an antistatic layer. It is made up of. In other words, the structure of the optical protective film on the surface protective layer side is characterized by the structure of a two-coat system such as a surface protective layer / an antistatic layer / a substrate film. Layer / water resistant layer / antistatic layer / base film). That is, the number of coatings during production is reduced, and the surface protective layer has excellent cost performance.

Next, the surface protective layer and the antistatic layer will be described in detail.
The surface protective layer is formed using a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, and a polyisocyanate (C) as a film forming component. It is preferable to dissolve in a solvent or the like, or to apply a coating on the antistatic layer as a coating material for forming a surface protective layer without solvent and dry it to form a surface protective layer. The coating material for forming the surface protective layer in this case contains a resin (A) having an active hydrogen group in the molecule and a polyurethane resin (B) containing a polysiloxane group. Preferably it is added or contains a stabilized polyisocyanate.

  As the resin (A) having an active hydrogen group in the molecule, the following resins are preferably used. Polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer Resin, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin, alkyd resin, phenol resin, polyether, polyester, celluloses Chitosan and urethane resin can be used. Furthermore, at least one selected from these is preferably used. Of these, ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol and phenoxy resin are particularly preferable.

The active hydrogen group in the resin (A) having an active hydrogen group in the molecule is, for example, a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NRH (R is a hydrocarbon group), —NH _2. Etc.) and a thiol group (-SH). Among these, a hydroxyl group is preferably used. When the resin has an active hydrogen group in the molecule, it can be used as the resin (A) 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 polyurethane resin (B) containing a polysiloxane group will be described below. The polysiloxane group is contained as a polysiloxane segment in the polyurethane resin (B) containing the polysiloxane group, and is contained in the main chain of the polyurethane resin or in a branched state. That is, if the polysiloxane used as a raw material is a double-end reactive type, it is contained in the trunk portion which is the main chain of the polyurethane resin, and if it is a single-end or branched reaction type, it is contained in a state branched from the main chain of the polyurethane resin. Become.

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

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

(1) Amino-modified polysiloxane compound

(2) Epoxy-modified polysiloxane compound

(3) Alcohol-modified polysiloxane compound

(4) Mercapto-modified polysiloxane compound

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

  Particularly preferred compounds in the present invention are polysiloxane compounds having two hydroxyl groups or amino groups. In addition to these, a polylactone (polyester) -polysiloxane compound obtained by modifying a polysiloxane compound with a lactone, a polyethylene oxide-polysiloxane compound modified with ethylene oxide or propylene oxide, a polypropylene oxide-polysiloxane compound, and the like are also preferably used.

  Particularly preferred are compounds obtained by modifying polysiloxane compounds with lactones, and more preferred are polylactone-polysiloxane compounds obtained by modifying polysiloxane compounds having one or more active hydrogen groups in the molecule with lactones. Preferred lactones used here are β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, 7-heptanolide, 8-octanolide, γ-valerolactone, γ-caprolactone and δ-caprolactone. .

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

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

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

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

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

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

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

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

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

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

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

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

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

  The amount of the resin (A) having an active hydrogen group in the molecule and the polyurethane resin (B) containing a polysiloxane group is 100% by mass with respect to 100% by mass of the resin (A) and the resin (B). Resin (A) is 20-80 mass%, Preferably it is 30-60 mass%. On the other hand, the resin (B) is 80 to 20% by mass, preferably 70 to 40% by mass. If the amount of the resin (A) used exceeds 80% by mass, the reaction with the polyisocyanate (C) is accelerated, which causes a decrease in usable time and a decrease in adhesion, which is not preferable. If it is less than 20% by mass, the crosslinking density of the surface protective layer is lowered, and therefore, the solvent resistance to the solvent used for removing the contaminants and the scratch resistance are lowered, which is not preferable.

  The polyisocyanate (C), which is a component for forming the surface protective layer, can be either aromatic or aliphatic. Preferably, in the aromatic system, metaxylylene diisocyanate (MDI), toluylene diisocyanate (TDI). ), In the aliphatic system, it is a modified product such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and preferably contains three or more isocyanate groups in the molecule. Adducts of the above, and urethane prepolymers obtained by reacting low molecular weight polyols and polyamines to form terminal isocyanates are also preferably used. These are exemplified below with structural formulas, but are not limited thereto.

  The amount of polyisocyanate (C) used is 5 to 60 parts by mass with respect to 100 parts by mass of the resin (A) having an active hydrogen group in the molecule and the polyurethane resin (B) containing a polysiloxane group. Is 10-40 parts by mass. If the amount of the polyisocyanate (C) used exceeds 60 parts by mass, it is not preferable because the use time decreases and the physical properties of the surface protective layer decrease due to the increase of unreacted polyisocyanate. Since the crosslinking density is lowered, the solvent resistance, scratch resistance, adhesion to the substrate film and the like are lowered, which is not preferable.

  The antistatic layer is formed of a resin (A) having an active hydrogen group in the molecule, a polyisocyanate (C), and an antistatic agent (D) as a film-forming component, and these are dissolved in a solvent or the like. The antistatic layer is preferably formed by coating and drying on a base film as a coating material for forming an antistatic layer without solvent. In this case, the antistatic layer-forming coating material contains a resin (A) having an active hydrogen group in the molecule and an antistatic agent (D), and a polyisocyanate is added before use, or It preferably contains a stabilized polyisocyanate.

  As described above, the resin (A) having an active hydrogen group in the molecule is preferably the following resin. Polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer Resin, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin, alkyd resin, phenol resin, polyether, polyester, celluloses Chitosan and urethane resin can be used. Furthermore, at least one selected from these is preferably used. Of these, ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol and phenoxy resin are particularly preferable.

The active hydrogen group in the resin (A) having an active hydrogen group in the molecule includes, for example, a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NRH, —NH ₂ etc.) and a thiol group (— SH) and the like, and among these, a hydroxyl group is preferably used. When the resin has an active hydrogen group in the molecule, it can be used as the resin (A) as it is, but when the resin molecule does not have an active hydrogen group, a treatment such as modification is performed. An active hydrogen group can be added.

  As a preferable antistatic agent (D) used for the antistatic layer provided on the other surface different from the adhesive layer of the base film, polyvinyl alcohol, cation-modified polyvinyl alcohol, alkali metal salt-containing polyether (for example, polyethylene oxide) Alkali metal salt), alkali metal salt-containing ether polyurethane, polyamine, quaternary cation salt-containing acrylic resin, specially modified polyester, special cationic resin, cellulose derivative, polyacetylene, polyparaphenylene, polythiophene, polypyrrole, polyaniline and sulfonation Containing organic conductive materials such as polyaniline, metal oxides such as carbon black, tin oxide, zinc oxide and titanium oxide, various metal alkoxides, zinc antimonate sol and ITO powder. It is from the one or more selected such. Among these, a conductive filler is particularly preferable. An antistatic function is imparted by coating these with a thin film to form a film.

  Among the antistatic agents, 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 hexafluoride. Examples include lithium phosphate, lithium trifluoromethanesulfonate, lithium pentafluoroethanesulfonate, lithium bispentafluoroethanesulfonimide, tetraethylammonium borofluoride, tetraethylammonium hexafluorophosphate, and potassium bistrifluoromethanesulfonimide. .

  Among the antistatic agents, for example, polyamines include epomin (manufactured by Nippon Shokubai Co., Ltd.), polyallylamine (manufactured by Nitto Boseki Co., Ltd.), etc., and quaternary cationic polymers include, for example, elecondo (manufactured by Soken Chemical Co., Ltd.), dirimer ( Nippon Pure Chemical 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.), Fcol (manufactured by Matsumoto Yushi Co., Ltd.) In the metal alkoxide system, for example, use of various alkoxysilanes, various alumina sols, Colcoat (manufactured by Colcoat Co.), Cellax (zinc antimonate sol, Nissan Chemical Co., Ltd.) and the like is preferable.

  The polyisocyanate (C), which is a component for forming the antistatic layer, can be either aromatic or aliphatic. Preferably, in the aromatic system, metaxylylene diisocyanate (MDI), toluylene diisocyanate (TDI). ), In the aliphatic system, it is a modified product such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and preferably contains three or more isocyanate groups in the molecule. Adducts of the above, and urethane prepolymers obtained by reacting low molecular weight polyols and polyamines to form terminal isocyanates are also preferably used.

  The amount of the polyisocyanate (C) used is 5 to 60 parts by mass, preferably 10 to 40 parts by mass with respect to 100 parts by mass of the resin (A) having an active hydrogen group in the molecule and the antistatic agent (D). Part. If the amount of the polyisocyanate (C) used exceeds 60 parts by mass, it is not preferable because the use time decreases, and the physical properties of the antistatic layer deteriorate due to the increase of unreacted polyisocyanate. Since the crosslinking density is lowered, the solvent resistance, scratch resistance, adhesion to the substrate film and the like are lowered, which is not preferable.

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

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

  In addition, when forming the surface protective layer of this invention, the resin (A) which has an active hydrogen group in the said molecule | numerator, the polyurethane resin (B) containing a polysiloxane group, and polyisocyanate (C) are contained. Use a coating for forming the surface protective layer. When the antistatic layer of the present invention is formed, the antistatic layer is formed containing the resin (A) having an active hydrogen group in the molecule, the antistatic agent (D), and the polyisocyanate (C). Use paint. 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 film thickness of the base film is preferably 20 to 100 μm, more preferably 25 to 40 μm. These base films may be subjected to corona treatment, antistatic treatment, easy adhesion treatment, itro treatment, and the like, if necessary.

  The optical protective film of the present invention can be manufactured by a conventionally known method using the antistatic layer-forming coating material and the surface protective layer-forming coating material, and the manufacturing method itself is not particularly limited. In addition, the materials other than the surface protective layer forming material such as the base film and the adhesive layer forming material and the antistatic layer forming material can be known materials, and are not particularly limited. In the formation of the surface protective layer and the antistatic layer of the optical protective film of the present invention, the surface protective layer-forming coating material and the antistatic layer-forming coating material of the present invention are coated on the surface of the substrate film by a conventionally known method ( The back surface is coated on the pressure-sensitive adhesive layer) so that the dry thickness is about 0.01 to 0.5 μm to form a film.

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

  The polyisocyanate (C) that forms the surface protective layer and the antistatic layer crosslinks the components in the surface protective layer forming material and the components in the antistatic forming material. It is possible to further improve the solvent resistance and scratch resistance (up to surface hardness) that can withstand contamination removal. The antistatic function is maintained because the base film is charged, but the function as an anchor layer is maintained by coating the surface protective layer forming coating with a thin film. Will not drop.

  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. Further, “parts” in the following text indicate mass parts, and “%” indicates mass%.

[Synthesis Examples 1 to 3]
A reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a reflux condenser was substituted with nitrogen gas, and then the lactone compound and siloxane compound described in Table 1 were added to predetermined concentrations, and 100 ° C. under a nitrogen stream. The mixture was stirred until uniform. Subsequently, predetermined tetra-n-butyl titanate was added and reacted for 10 hours at a temperature of 180 ° C. under a nitrogen stream. As the reaction proceeds, the viscosity of the reactant increases. Thereafter, the reaction was continued at 180 ° C. under a reduced pressure of 5 mmHg for 1 hour to complete the reaction, and the non-reactive siloxane compound and unreacted substances contained in the starting siloxane compound were completely removed. The composition and properties of the resulting siloxane-modified polyester oligomer are shown in Table 1.

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

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

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

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

Aging condition: 40 ° C., 2 days EVOH; ethylene vinyl alcohol, trade name; F104 (ethylene copolymerization ratio = 32 mol%, melt index = 4.5 g / min .; 190 ° C., 2,160 g, Kuraray Co., Ltd.) Made)
-PVA; Partially saponified polyvinyl alcohol, trade name: PVA-217 (degree of saponification = 87 to 89, degree of polymerization = 1,700, manufactured by Kuraray Co., Ltd.)
YP-50S; phenoxy resin, trade name: phenotote YP-50S, (weight average molecular weight = 40,000, manufactured by Toto Kasei Kogyo Co., Ltd.)
BL-S; butyral group / acetyl group-containing polyvinyl alcohol copolymer, trade name: BL-S (hydroxyl group = 22 mol%, acetyl group = 3-5 mol%, butyral degree = 70 mol% or less, Sekisui Chemical Co., Ltd. ) Made)
-PHDI; HDI biuret type polyisocyanate, trade name: Duranate 24A-100 (manufactured by Asahi Kasei Chemicals Corporation)
D-1; cationic (quaternary ammonium salt) polyacrylic ester, trade name: Jurimer SP-50TF (manufactured by Nippon Pure Chemical Co., Ltd.)
D-2; polyester / siloxane hybrid, trade name: Colcoat SP-2014S (manufactured by Colcoat)
DMF: dimethylformamide

  Using the paints obtained in the above Examples and Comparative Examples, the thickness after drying the antistatic layer-forming paint on the surface of a 38 μm thick polyethylene terephthalate film (manufactured by Toray) by gravure printing is 0.3 μm. Then, after drying the water in a dryer at 110 ° C. for 60 seconds, each of the surface protective layer-forming paints obtained in each of the Examples and Comparative Examples has a thickness after drying of 0. After coating to a thickness of 2 μm, the solvent was dried in a dryer at 110 ° C. for 90 seconds. When the paints of Examples 1 to 4 and Comparative Examples 1 and 3 were used, they were aged in an oven at 40 ° C. for 48 hours after application and drying to form a surface protective layer and an antistatic layer. Since Comparative Example 2 did not use PHDI, it was tested with the solvent dried without aging.

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

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

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

<Transparency>
Using a direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd., the haze value of the protective film for optics was measured.
Haze value = Measured value−Haze value of substrate ○: Haze value is less than 1.0 Δ: Haze value is 1.0 or more and less than 5.0 ×: Haze value is 5.0 or more

<Solvent resistance>
1 g of a solvent was hung on the surface of the optical protective film, and the appearance of the coating film on the surface protective layer when rubbed with a load of 50 g / cm ² was observed. The evaluation was performed on four types of solvents, methyl ethyl ketone (MEK), toluene, isopropyl alcohol (IPA), and ethyl acetate (EA).
○: There is no change in the coating film appearance of the surface protection layer △: The coating film appearance of the surface protection layer is slightly changed ×: The coating film appearance of the surface protection layer is changed

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

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

<Adhesion>
The adhesion between the coating film of the surface protective layer of the protective film for optics and the substrate PET film was measured by a cross cut test (cellophane tape peeling cross-cut method).
◎: Unpeeled squares are 95% or more ○: Unpeeled squares are less than 95% 70% or more Δ: 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 temperature: 23 ° C., humidity: 65% RH, and an average value of 5 measurements. The dynamic friction coefficient is preferably in the range of 0.18 to 0.28.

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

According to the present invention, in addition to antistatic properties, scratch prevention (scratch properties), and easy cleaning of contaminants (solvent resistance is required because they are washed with an organic solvent), printing suitability (used for process control) An optical protective film excellent in the suitability of the printer ink), adhesion to the film substrate, transparency, and moderate slipperiness. Furthermore, an optical protective film capable of a two-coat system having a surface protection function and an antistatic function is provided.

Claims (8)

  In the optical protective film comprising a base film, an adhesive layer provided on one side of the base film, and a surface protective layer provided on the other side of the base film via an antistatic layer, The surface protective layer is formed using a resin (A) having an active hydrogen group in the molecule, a polyurethane resin (B) containing a polysiloxane group, and a polyisocyanate (C) as a film-forming component, and the above antistatic An optical protective film, wherein the layer is formed using a resin (A) having an active hydrogen group in the molecule, a polyisocyanate (C), and an antistatic agent (D) as a film-forming component.   Resin (A) having an active hydrogen group in the molecule is polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl Alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin The optical protective film according to claim 1, which is at least one selected from alkyd resins, phenol resins, polyethers, polyesters, celluloses, chitosan, and urethane resins.   The polyurethane resin (B) containing a polysiloxane group is a polysiloxane compound having at least one active hydrogen group in the molecule and / or a compound obtained by copolymerizing the polysiloxane compound and a lactone, a polyisocyanate, and a polyol. The protective film for optical use according to claim 1, which is a polyurethane resin obtained by reacting with a polyamine and having a weight average molecular weight of 5,000 to 500,000.   The optical protective film according to claim 1, wherein the antistatic agent is a conductive filler. The optical protective film according to claim 1, wherein the surface resistance value is 10 ¹⁰ Ω / cm ² or less. In the optical protective film according to any one of claims 1 to 5, a resin (A) having an active hydrogen group in the molecule, a polyisocyanate (C), and an antistatic agent (D) are used as a film forming component. A paint for forming a surface protective layer provided via a formed antistatic layer, comprising a resin (A) having an active hydrogen group in the molecule, and a polyurethane resin (B) containing a polysiloxane group Is dissolved in an organic solvent, and polyisocyanate (C) is added before use, or stabilized polyisocyanate (C) is contained (except when an antistatic agent is included) . A paint for forming a surface protective layer, wherein the resin (A), the resin (B), and the polyisocyanate (C) are used as film-forming components.   The resin (A) is an ethylene-vinyl alcohol copolymer, a partially saponified polyvinyl alcohol or a phenoxy resin, and the resin (B) contains a polysiloxane compound containing an amino group or a hydroxyl group in the molecule, and a lactone. The coating material for forming a surface protective layer according to claim 6, which is a reaction product of a copolymer of the above, a polyisocyanate, and a polyol.   The resin (A) is 20 to 80% by mass of the total amount (100% by mass) of the resin (A) and the resin (B), and the resin (B) is 80 to 20% by mass. The coating material for forming a surface protective layer according to 1.