JP2009102458A - Protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective film having high solvent resistance against an alcohol-based solvent and suppressing reduction in an antistatic function by an alcohol-based solvent. <P>SOLUTION: The protective film comprises a base film, a contamination preventing layer containing a boron-based antistatic agent and a release agent formed on one surface of the base film, and a tacky layer formed on the other surface of the base film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a protective film that protects, for example, the surface of an optical member, and more specifically, relates to a protective film that has excellent solvent resistance against alcohol solvents.

  In general, the protective film is bonded to the protected body with an adhesive layer provided on the protective film in order to prevent scratches, contamination, and the like on the protected body. For example, such a protective film is bonded to an optical member such as a polarizing plate or a retardation plate to be bonded to a liquid crystal cell via an adhesive layer in order to protect it from scratches and dirt. Then, the protective film is peeled off and removed at the stage where the surface protection is no longer necessary by bonding the optical member to the liquid crystal cell.

  As such a protective film, one having an antistatic function has been conventionally known. This function is to prevent dust or the like from adhering to the surface of the protected object or destroying the TFT element of the liquid crystal cell due to static electricity generated when the protective film is peeled off from the protected object. It is. On the other hand, what has a peeling function is conventionally known as a protective film. This function, for example, when the laminated body in which the protective film and the object to be protected are bonded is cut, the adhesive protrudes from the cut surface, and as a result, the laminated body is cut out. It is a function for preventing the malfunction that an adhesive will adhere to a base film.

  As a protective film having an antistatic function and a peeling function, a protective film in which an antistatic layer and a peeling layer are laminated as separate layers is generally known. On the other hand, a protective film having a layer having an antistatic function and a peeling function has been developed. For example, Patent Document 1 discloses a surface protective film in which a layer including a component having antistatic properties and a component having antifouling properties (peelability) is provided on one side of a plastic film. As described above, by providing a layer having both an antistatic function and a peeling function, the manufacturing process can be simplified as compared with the case where two antistatic layers and a peeling layer are separately provided. Have.

  Patent Document 2 discloses an antistatic agent comprising a charge transfer-type conjugate obtained by reacting a specific polyamino compound with a semipolar organic boron compound having a specific atomic group. Has been.

JP 11-256116 A Japanese Patent No. 2872817

  However, the protective film described in Patent Document 1 described above has a problem of low solvent resistance against alcohol solvents. In the actual manufacturing process, when a laminated body in which a protective film and an object to be protected are bonded is cut, and the cut laminated body is cut into pieces, a magic is used to protect various information such as product information. May be described directly. The information written in Magic is wiped off with an alcohol solvent when it is no longer needed. At that time, the alcohol-based solvent wipes off the antistatic component present on the surface of the protective film together with the magic ink component, and there is a problem that the antistatic function of the protective film is greatly reduced. Further, even when the surface of the protective film is washed with an alcohol-based solvent, there is a problem that the antistatic function of the protective film is also greatly reduced.

  The present invention has been made in view of the above circumstances, and has as its main object to provide a protective film that has high solvent resistance to alcohol solvents and can suppress a decrease in the antistatic function due to alcohol solvents. To do.

  In order to solve the above problems, in the present invention, a base film, a stain preventing layer formed on one surface of the base film and containing a boron-based antistatic agent and a release agent, and the base material And a pressure-sensitive adhesive layer formed on the other surface of the film.

  According to the present invention, by adding a boron antistatic agent to the antifouling layer, a antifouling layer having a high solvent resistance against alcohol solvents such as isopropyl alcohol (IPA) and having an excellent antistatic function can be obtained. Can do. Thereby, even if it is a case where the dirt prevention layer of a protective film is wiped off with the waste containing an alcohol solvent, the fall of the antistatic function of a dirt prevention layer can be suppressed.

In the said invention, it is preferable that the surface specific resistance value of the said antifouling layer is 1.0 × 10 ⁹ Ω / □ or less. It is because it can be set as the protective film excellent in antistatic property.

In the said invention, when the solvent wiping test which wipes off the surface of the said antifouling layer was performed using the waste impregnated with isopropyl alcohol, the surface intrinsic value of the said antifouling layer after the said solvent wiping test is 1. It is preferably 0 × 10 ¹¹ Ω / □ or less. This is because, within the above range, a sufficient antistatic function can be exhibited even after wiping off the solvent.

  In the said invention, it is preferable that the film thickness of the said stain | pollution | contamination prevention layer exists in the range of 0.50 micrometer-1.50 micrometer. If the film thickness is too small, the desired antistatic function and peeling function may not be exhibited. If the film thickness is too large, the effect does not change and the cost increases.

  In the said invention, it is preferable that the said peeling agent is a polymer which has long-chain alkyl. This is because a good peeling function can be exhibited.

  Further, in the present invention, an antifouling layer-forming coating solution used for forming an antifouling layer of a protective film, comprising a boron-based antistatic agent and a release agent, A forming coating solution is provided.

  According to the present invention, by using a boron antistatic agent, it is possible to obtain an antifouling layer having high solvent resistance against alcohol solvents such as IPA.

  In this invention, there exists an effect that the solvent resistance with respect to alcohol solvent is high, and the protective film which can suppress the fall of the antistatic function by alcohol solvent can be obtained.

  Hereinafter, the protective film and antifouling layer forming coating solution of the present invention will be described in detail.

A. Protective film First, the protective film of this invention is demonstrated. The protective film of the present invention is a base film, a stain preventing layer formed on one surface of the base film, containing a boron antistatic agent and a release agent, and the other surface of the base film. And an adhesive layer formed on the substrate.

  According to the present invention, by adding a boron antistatic agent to the antifouling layer, it is possible to obtain an antifouling layer having high solvent resistance against alcoholic solvents such as IPA and excellent antistatic function. Thereby, even if it is a case where the dirt prevention layer of a protective film is wiped off with the waste containing an alcohol solvent, the fall of the antistatic function of a dirt prevention layer can be suppressed. Furthermore, as a result, it is possible to prevent dust or the like from adhering to the surface of the protected body or destroying the TFT element of the liquid crystal cell or the like due to static electricity generated when the protective film is peeled from the protected body.

  In addition, according to the present invention, since the antifouling layer has both an antistatic function and a peeling function, the manufacturing process can be simplified and the thickness of the protective film can be reduced. Have advantages. By reducing the film thickness of the protective film, for example, when the protective film is wound up in a roll shape, a smaller original fabric can be obtained.

  Next, the protective film of this invention is demonstrated using drawing. FIG. 1 is a schematic cross-sectional view showing an example of the protective film of the present invention. A protective film 10 shown in FIG. 1 includes a base film 1, a stain preventing layer 2 formed on one surface of the base film 1 and containing a boron-based antistatic agent and a release agent, and a base film. 1 and the pressure-sensitive adhesive layer 3 formed on the other surface. FIG. 2 is a side view showing a winding state of the protective film 10 shown in FIG.

  Next, the reason why the protective film of the present invention is excellent in solvent resistance against alcohol solvents will be described. The following general formula (I) shows an example of a conventional quaternary ammonium salt antistatic agent.

The conventional quaternary ammonium salt antistatic agent has a long alkyl chain, and the hydrophobicity of this part is high. However, as indicated by the broken line portion, the ionized functional group (CH ₃ Cl ⁻ ) portion has high hydrophilicity and high affinity with an alcohol solvent such as IPA. Therefore, it is considered that a conventional protective film having a quaternary ammonium salt antistatic agent has low solvent resistance against alcohol solvents.
On the other hand, the following general formula (II) shows an example of an atomic group of a semipolar organic boron compound constituting the boron antistatic agent used in the present invention.

In general formula (II), q is 0 or 1, and A represents “— (X) _a — (Y) _b — (Z) _c —”. X and Z are each a C100 or less polyether compound residue having one ether residue at the end, and Y is represented by the following general formula (III-1) or general formula (III-2). It is what is done. A, b, and c are 0 or 1, respectively. P is an integer of 10 to 1,000.

  The boron antistatic agent represented by the general formula (II) has a weak polar state although the broken line portion is in a polar state. Furthermore, there are few polar groups in the structure. As a result, the overall hydrophobicity is high, and the affinity with alcohol solvents such as IPA is low. Therefore, the protective film having a boron antistatic agent is considered to have high solvent resistance against alcohol solvents.

Further, as described later, the protective film of the present invention may have a separator that covers the adhesive layer, or may have no separator (separator-less type). It is preferable that This is because the cost can be reduced because there is no separator discarded after peeling.
Hereinafter, the protective film of the present invention will be described for each configuration.

1. Antifouling Layer The antifouling layer used in the present invention will be described. The antifouling layer used in the present invention is formed on one surface of a base film described later and contains a boron antistatic agent and a release agent. In the present invention, by using a boron-based antistatic agent, a protective film having excellent solvent resistance against alcohol solvents and excellent antistatic function can be obtained.

(1) Boron antistatic agent First, the boron antistatic agent used in the present invention will be described. The boron antistatic agent used in the present invention has at least boron (B) as a constituent element. The boron antistatic agent used in the present invention is not particularly limited as long as it has solvent resistance to an alcohol solvent and an antistatic function, but specifically, the main chain and / or Alternatively, a charge transfer conjugate obtained by reacting a polyamino compound having at least two basic nitrogen atoms in the side chain with a semipolar organic boron compound having an atomic group represented by the following general formula (IV) And the like.

(In general formula (IV), R ₁ , R ₂ , R ₃ and R ₄ are the same or different and each represents hydrogen, a lower alkyl group, a lower alkoxyl group or a lower alkoxy lower alkyl group, and n is 0 or 1 .)

  In the present invention, a reaction product of a semipolar organic boron polymer compound and a monoamine is referred to as a nitrogen-boron complex (hereinafter abbreviated as N · B complex). First, the polyamino compound that is a raw material of the N component of the N · B complex has at least two basic nitrogens in the main chain and / or side chain, such as ethylenediamine, propylenediamine, hexamethylenediamine, dimethyl. Aminopropylamine, phenylenediamine, tolylenediamine, methyliminobispropylamine, piperazine, polyethyleneimino and its ethylene oxide adduct, propylene oxide adduct or ethylene oxide-propylene oxide coadduct, triethylenediamine, polyvinylpyridine, poly (dimethyl) Aminoethyl) acrylate, poly (dimethylaminoethyl) metallate, poly (diethylaminoethyl) acrylate, poly (diethylaminoethyl) methacrylate, poly (dimethyl) Le aminopropyl) acrylamide, poly (dimethylaminopropyl) methacrylamide, poly (dimethylaminomethyl styrene), diallylamine - isobutylene alternating copolymer, diallylamine - sulfur dioxide alternating copolymer, and the like.

On the other hand, a semipolar organic boron compound having an atomic group represented by the general formula (IV) is used as a raw material for the component B. In the formula, “lower” in the substituents represented by R ₁ , R ₂ , R ₃ and R ₄ refers to those having 1 to 6 carbon atoms, more preferably those having 1 to 2 carbon atoms. Specific examples of the semipolar organoboron compound include two to three adjacent hydroxyl groups or α-position, γ shown in, for example, Yukagaku, Vol. 29, No. 12, 893-900 (1980). Di (glycerin) borate of 2: 1 type polyol borates and monovalent carboxylic acid esters thereof, alkylene of di (glycerin) borate, which are composed of polyhydric alcohol residues having two hydroxyl groups which are opposite in positional relationship Oxide adduct and monovalent carboxylic acid ester, di (catechol) borate, di (1,2-propylene glycol) borate, di (1,3-propylene glycol) borate, di (1,3-butylene glycol) borate, di (2-Methyl-2,4-pentanediol) borate, di (2,2,4-trimethyl-1,3-pentanediol) bora , Di (2-ethyl-1,3-hexanediol) borate, di (2-methoxy-1,3-propylene glycol) borate, di (2-ethoxy-1,3-propylene glycol) borate, di ( 2-methyl-2-methoxymethyl-1,3-propylene glycol) borate, di (2-methyl-2-ethoxymethyl-1,3-propylene glycol) borate, di (2-ethyl-2-methoxymethyl-1) , 3-propylene glycol) borate, di (2-ethyl-2-ethoxymethyl-1,3-propylene glycol) borate, di (2,2-di (methoxymethyl) -1,3-propylene glycol) borate, di (2,2-di (ethoxymethyl) -1,3-propylene glycol) borate and the like. Moreover, you may use the semipolar organic boron high molecular compound represented by general formula (II) mentioned above.

  Various methods can be employed for producing an N · B complex type charge transfer type conjugate using the above N component and B component raw materials, but it is preferable to satisfy the following conditions. Specifically, the charging ratio is such that the amount of semipolar boron in the B component is 0.01 to 1, preferably 0.05 to 1, with respect to one basic nitrogen in the N component. The two components are reacted at 20 to 200 ° C., preferably 50 to 150 ° C. under normal pressure. In this case, the reaction proceeds more easily when a polar solvent such as alcohol, ether or ketone is added.

  The amount of the boron antistatic agent contained in the antifouling layer is not particularly limited as long as a desired antistatic function can be exhibited. For example, the amount is within the range of 10 wt% to 99 wt%, and in particular 30 It is preferable to be in the range of 80% by weight to 80% by weight, particularly 40% by weight to 60% by weight.

(2) Release agent Next, the release agent used in the present invention will be described. The release agent used in the present invention imparts a release function to the antifouling layer. The release agent used in the present invention is not particularly limited as long as it can exhibit a desired release function, and a general release agent can be used.

  Among them, in the present invention, the release agent is preferably a polymer having a long-chain alkyl, and more preferably a copolymer of alkyl acrylate and acrylic acid having an alkyl chain having 12 or more carbon atoms, particularly 16 to 20 carbon atoms. This is because a good peeling function can be exhibited.

  Among these, particularly preferred is a copolymer obtained by long-chain alkylation of polyvinyl alcohol or polyethyleneimine with chlorinated alkyloyl or alkyl isocyanate. Specifically, polyvinyl--obtained by reaction of polyvinyl alcohol with octadecyl isocyanate. Examples thereof include N-octadecyl carbamate and polyethylene imine-N-octadecyl carbamate obtained by reaction of polyethylene imine and octadecyl isocyanate. In the present invention, a silicone release agent or a fluorine release agent can be used as the release agent.

  The ratio of the content of the release agent and boron antistatic agent in the antifouling layer varies depending on the type of release agent and boron antistatic agent used, etc., but relative to 100 parts by weight of the boron antistatic agent. The release agent is, for example, preferably in the range of 10 parts by weight to 500 parts by weight, more preferably in the range of 20 parts by weight to 350 parts by weight, and particularly preferably in the range of 30 parts by weight to 250 parts by weight.

  The amount of the release agent contained in the antifouling layer is not particularly limited as long as a desired release function can be exhibited. For example, the amount is within the range of 30% by weight to 80% by weight, especially 40% by weight to 60%. It is preferable to be in the range of% by weight.

(3) Other components In this invention, in order to improve the intensity | strength of a stain | pollution | contamination prevention layer, the adhesiveness to a base film, etc., you may add a binder to a stain | pollution | contamination prevention layer.

  The binder is not particularly limited. For example, thermoplastic resins such as thermoplastic polyester resins, acrylic resins, and polyvinyl resins and / or thermosetting acrylic resins, urethane resins, melamine resins, epoxy resins, and the like are used. It is preferable to contain a polymer compound such as a curable resin, and the crosslinking agent is selected from methylolated or alkylolized melamine-based, urea-based, glyoxal-based, acrylamide-based compounds, epoxy compounds, and polyisocyanates. It is particularly preferable to contain at least one kind.

  The amount of the binder contained in the antifouling layer is not particularly limited, and it is preferable to select appropriately so that the desired antistatic function and peeling function can be obtained.

(4) Antifouling layer The antifouling layer used in the present invention contains at least a boron antistatic agent and a release agent. Furthermore, you may contain the binder etc. which were mentioned above as needed.

The antistatic function of the antifouling layer used in the present invention can be evaluated by the surface resistivity of the antifouling layer. The surface resistivity value of the antifouling layer is, for example, 1.0 × 10 ¹¹ Ω / □ or less, particularly 1.0 × 10 ¹⁰ Ω / □ or less, and particularly 1.0 × 10 ⁹ Ω / □ or less. preferable. This is because a sufficient antistatic function can be exhibited within the above range. In the present invention, the surface specific resistance value can be measured with a digital insulation meter (for example, Lorester GP MCP-T610, manufactured by Mitsubishi Chemical Corporation) in accordance with JIS K7194 in accordance with JIS K7194. In addition, the value of said surface specific resistance value says the value before the solvent wiping test using the alcohol solvent normally described below.

In the present invention, when a solvent wiping test using an alcohol solvent is performed, it is preferable that the antistatic property of the antifouling layer is little deteriorated before and after the test. The “solvent wiping test” in the present invention is a test in which the operation of wiping the surface of the antifouling layer of the protective film under a load of 500 g using a cloth impregnated with isopropyl alcohol (IPA) is performed five times. Say. In the present invention, the surface intrinsic value of the antifouling layer after the solvent wiping test is preferably 1.0 × 10 ¹¹ Ω / □ or less, more preferably 6.0 × 10 ¹⁰ Ω / □ or less.

  The peeling function (peeling force) of the antifouling layer used in the present invention can be evaluated by measuring the peel strength using a predetermined adhesive tape. In the present invention, the peel strength of the antifouling layer refers to the peel strength measured by the following method. Peel strength is obtained by cutting a protective film into a strip-shaped test piece having a width of 25 mm and a length of 150 mm, and then having a pressure-sensitive adhesive tape having an acrylic pressure-sensitive adhesive (manufactured by Nitto Denko Corporation) Polyester adhesive tape No. 31B) is affixed to the test piece, and then measured by peeling the adhesive tape in the length direction of the test piece at a peeling angle of 180 °, a peeling speed of 300 mm / min, and room temperature. Can do. For example, a universal testing machine 5565 manufactured by Instron can be used for the peel strength measurement. The peeling force of the antifouling layer is, for example, in the range of 0.01 N / 25 mm to 3.00 N / 25 mm, in particular in the range of 0.10 N / 25 mm to 2.00 N / 25 mm, particularly 0.20 N / 25 mm to 1. A range of 50 N / 25 mm is preferable.

  The film thickness of the antifouling layer is, for example, preferably in the range of 0.05 μm to 5.00 μm, more preferably in the range of 0.10 μm to 3.00 μm, and particularly preferably in the range of 0.50 μm to 1.50 μm. If the film thickness is too small, the desired antistatic function and peeling function may not be exhibited. If the film thickness is too large, the effect does not change and the cost increases.

2. Next, the adhesive layer used in the present invention will be described. The pressure-sensitive adhesive layer used in the present invention is formed on the surface of the substrate film on the side opposite to the above-described stain prevention layer. The adhesive layer used in the present invention is not particularly limited as long as desired adhesiveness can be exhibited, and the same adhesive layer as that used for a general protective film can be used.

  The pressure-sensitive adhesive layer used in the present invention contains at least a pressure-sensitive adhesive, and may contain a crosslinking agent or the like as necessary. In the present invention, when the pressure-sensitive adhesive layer contains a crosslinking agent, the pressure-sensitive adhesive layer is obtained by crosslinking the pressure-sensitive adhesive with a crosslinking agent. Hereinafter, each member will be described.

(1) Adhesive The adhesive used in the present invention is not particularly limited as long as it has desired adhesiveness. Examples thereof include acrylic, urethane, rubber, and silicone adhesives. be able to. In the present invention, an acrylic pressure-sensitive adhesive is particularly preferable. This is because it is excellent in transparency, durability and heat resistance, and is low in cost. Examples of the acrylic pressure-sensitive adhesive include an acrylate copolymer obtained by copolymerizing an acrylate ester with another monomer.

  Examples of the acrylate ester include ethyl acrylate, acrylate-n-butyl, acrylate-2-ethylhexyl, isooctyl acrylate, isononyl acrylate, hydroxylethyl acrylate, propylene glycol acrylate, acrylamide, and glycidyl acrylate. Etc. In the present invention, ethyl acrylate, acrylate-n-butyl, acrylate-2-ethylhexyl, and the like are particularly preferable. This is because the adhesiveness to the protected object is good. Moreover, the said acrylic ester may be used independently, and multiple may be used in mixture.

  Examples of the other monomer include, for example, methyl acrylate, methyl methacrylate, styrene, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, itaconic acid, hydroxylethyl acrylate, hydroxylethyl methacrylate, propylene glycol acrylate, Examples include acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate, and n-ethylhexyl methacrylate. In the present invention, n-ethylhexyl methacrylate is particularly preferable. Moreover, the said other monomer may be used independently, and two or more may be mixed and used.

  The weight average molecular weight (Mw) of the acrylic ester copolymer used as the acrylic pressure-sensitive adhesive used in the present invention is particularly limited as long as the acrylic pressure-sensitive adhesive exhibits a desired adhesive force. However, it is preferably in the range of 200,000 to 2,500,000, and more preferably in the range of 600,000 to 2,200,000. The weight average molecular weight is a value in terms of polystyrene when measured by gel permeation chromatography (GPC).

(2) Crosslinking agent Examples of the crosslinking agent used in the present invention include an epoxy crosslinking agent and an isocyanate crosslinking agent.
As said epoxy type crosslinking agent, a polyfunctional epoxy type compound can be mentioned, for example. Specific examples of the polyfunctional epoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neodymium Examples include pentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutadiene diglycidyl ether.

  Examples of the isocyanate-based crosslinking agent include a polyisocyanate compound, a trimer of a polyisocyanate compound, a urethane prepolymer having an isocyanate group at a terminal obtained by reacting a polyisocyanate compound and a polyol compound, or such Examples include trimers of urethane prepolymers. Specific examples of the polyisocyanate compound include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and diphenylmethane-4,4 ′. -Diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate and the like.

  The content of the crosslinking agent used in the present invention varies depending on the type of the crosslinking agent, but is within the range of 2.0 parts by weight to 10.0 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. Among these, it is preferable that the content be in the range of 3.5 parts by weight to 6.0 parts by weight.

(3) Other additives The pressure-sensitive adhesive layer used in the present invention contains a metal chelating agent, an antioxidant, an ultraviolet absorber, a photopolymerization initiator, and the like as necessary in addition to the above-described crosslinking agent. May be.

(4) Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer used in the present invention contains at least a pressure-sensitive adhesive, and may contain a crosslinking agent or the like as necessary. The thickness of the pressure-sensitive adhesive layer is appropriately set according to the use of the protective film, but is, for example, in the range of 3 μm to 200 μm, especially in the range of 4 μm to 100 μm, particularly in the range of 5 μm to 50 μm. It is preferable.

3. Next, the base film used in the present invention will be described. The base film used in the present invention retains the above-described antifouling layer and adhesive layer. As a base film used for this invention, if it has desired flexibility and transparency, it will not specifically limit, The same thing as the base film used for a general protective film is used. be able to. Especially, in this invention, it is preferable that the transparency of a base film is high. This is because an optical inspection can be performed with high accuracy in a state where a protective film is attached to an object to be protected such as an optical member.

  Specific examples of the base film include olefin resins such as polyethylene, polypropylene, polyvinyl alcohol or ethylene-vinyl alcohol copolymer, polyfluorinated ethylene, polyvinylidene fluoride, or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. Fluorine resin such as polyvinyl chloride, polyvinyl chloride such as polyvinyl chloride or polyvinylidene chloride, acrylic resin such as polymethyl methacrylate, sulfone resin such as polyethersulfone, ketone resin such as polyetheretherketone, polyethylene terephthalate And thermoplastic polyester resins such as polyethylene naphthalate, polyimide resins, and polyamide resins. In the present invention, among them, a thermoplastic polyester resin is preferable, and polyethylene terephthalate is particularly preferable. It is because it is excellent in transparency.

  The base film used in the present invention has a surface treatment such as corona treatment and plasma treatment and a primer (primer) on the surface of the base film in order to improve the adhesion with the adhesive layer and / or the antifouling layer. May be applied.

  The thickness of the base film is not particularly limited as long as it can be bonded with good adhesion when bonded to a protected body and can be sufficiently protected from scratches, etc. Although it is appropriately set according to the use of the protective film, it is preferably in the range of 12 μm to 100 μm, in particular in the range of 16 μm to 50 μm, particularly in the range of 25 μm to 38 μm. This is because if it is thicker than the above range, it may be difficult to bond to the protected body with good adhesion. Further, if it is thinner than the above range, it may be difficult to sufficiently protect from scratches and the like.

4). Protective film The protective film of this invention has a base film, a stain | pollution | contamination prevention layer, and an adhesion layer at least. As described above, since the protective film of the present invention has a great feature in the structure of the antifouling layer, the protective film may have a separator that covers the adhesive layer, or may not have a separator (separator-less Type). Especially, in this invention, it is preferable that a protective film is a separatorless type. This is because the cost can be reduced because there is no separator discarded after peeling.

  As shown in FIG. 2 described above, the protective film of the present invention is usually wound in a roll shape. That is, in this invention, the protective film original fabric by which the protective film mentioned above was wound by roll shape can be provided.

  Moreover, it is preferable that the protective film of this invention is excellent in light transmittance. This is because an optical inspection can be performed with high accuracy in a state where a protective film is attached to an object to be protected such as an optical member. The total light transmittance of the protective film is, for example, preferably in the range of 85% to 99%, and more preferably in the range of 90% to 99%. In the present invention, the total light transmittance can be measured with an integrating sphere turbidimeter (for example, NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K-7361. On the other hand, the haze of the protective film is, for example, preferably in the range of 0.5% to 12.0%, and more preferably in the range of 1.0% to 10.0%. In the present invention, haze can be measured with an integrating sphere turbidimeter (for example, NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K-7136.

  Examples of the use of the protective film of the present invention include an optical member use. That is, the protective film of the present invention is preferably used for protecting the surface of the optical member. Specific examples of the optical member include an optical member for a liquid crystal cell, an optical member for a lens, an optical member for optical nanoimprint, and the like. Among these, an optical member for a liquid crystal cell is preferable. This is because in recent years, the liquid crystal cell has been greatly increased in screen size and definition, and an improvement in the antistatic function has been demanded. Specific examples of the optical member for a liquid crystal cell include a deflection plate and a retardation plate. Specific examples of the optical member for lenses include a microlens array. Specific examples of the optical member for optical nanoimprinting include a template for optical nanoimprinting. On the other hand, applications other than optical members include, for example, steel plate protection, window glass protection, and plastic protection (for example, a personal computer housing).

  The method for producing the protective film of the present invention is not particularly limited as long as a desired protective film can be obtained. As an example of a method for producing a protective film, a stain prevention layer is formed by applying and drying a coating solution for forming a stain prevention layer (a coating solution for forming a stain prevention layer) on one side of a base film. Then, an adhesive layer is formed by applying and drying a coating liquid for forming an adhesive layer (coating liquid for forming an adhesive layer) on the surface of the base film on which the antifouling layer is not formed. The method of doing can be mentioned. In addition, the order which forms a stain | pollution | contamination prevention layer and an adhesion layer can be selected arbitrarily.

  As a coating method for applying each coating solution, various known coating methods can be used, and examples thereof include a die coater, a comma coater, a knife coater, a gravure coater, and a roll coater.

  Further, the adhesive layer may be formed by directly applying to the base film as described above. For example, when the base film does not have solvent resistance to the solvent of the coating liquid, or for removing the solvent. In the case of not having the heat resistance required for the drying treatment, an adhesive layer may be formed by a transfer method. As an example of the transfer method, for example, by forming a stain prevention layer or an adhesive layer on a release film obtained by releasing the surface of a PET film with a fluorine release agent or a silicone release agent, There can be mentioned a method of preparing a transfer sheet, laminating the transfer sheet and the substrate film, and finally peeling the peelable film.

B. Next, the antifouling layer forming coating solution of the present invention will be described. The antifouling layer forming coating solution of the present invention is an antilayer forming coating solution used for forming the antifouling layer of the protective film, and contains a boron-based antistatic agent and a release agent. It is a feature.

  According to the present invention, by using a boron antistatic agent, it is possible to obtain an antifouling layer having high solvent resistance against alcohol solvents such as IPA.

  The antifouling layer-forming coating solution of the present invention contains at least a boron antistatic agent and a release agent, and usually contains a binder, a solvent, and the like. Since the boron-based antistatic agent, the release agent and other matters used in the present invention are the same as the contents described in the above “A. Protective film”, description thereof is omitted here.

  The solvent used in the antifouling layer forming coating solution is not particularly limited as long as it can dissolve and disperse the boron-based antistatic agent and the release agent. Specifically, methyl isobutyl ketone, Examples include cyclohexanone, benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, 1,4-dioxane, 1,2-dichloroethane, dichloromethane, chloroform, etc. Among them, toluene, methyl ethyl ketone, and methyl glycol ether are preferable.

  The solid content concentration of the antifouling layer forming coating solution is not particularly limited as long as a desired antifouling layer forming coating solution can be obtained. For example, it is 10.0% by weight or less. It is preferably within the range of 5% by weight to 5.0% by weight.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
(1) Formation of antifouling layer A single-sided corona-treated PET (S105 manufactured by Toray Industries, Inc.) having a thickness of 38 μm is prepared as a base film, and the antifouling layer-forming coating having the following composition is applied to the corona-treated surface of single-sided corona-treated PET. The working solution was applied by a gravure printing method under a drying condition of 50 ° C. for 30 seconds so that the film thickness after drying was 1 μm, and a stain prevention layer was formed on the base film. In this way, a laminate A was obtained.

(Composition of coating liquid for forming antifouling layer)
・ Release agent (polymer having long-chain alkyl, Pyroyl 1010 manufactured by Yushi Kogyo Co., Ltd.)
0.025 parts by weight-Boron-based antistatic agent represented by the following structural formula (A) 0.025 parts by weight-Toluene 4.95 parts by weight

[Example 2 to Example 4]
Laminates B to D were obtained in the same manner as in Example 1 except that the formulation of the antifouling layer forming coating solution was changed as shown in Table 1.

[Comparative Example 1]
A laminate E was obtained in the same manner as in Example 1 except that the stain prevention layer forming coating solution having the following composition was used.

(Composition of coating liquid for forming antifouling layer)
・ Release agent (polymer having long-chain alkyl, Pyroyl 1010 manufactured by Yushi Kogyo Co., Ltd.)
0.05 parts by weight, quaternary ammonium salt antistatic agent (Colcoat 121X-9, manufactured by Colcoat)
0.05 part by weight, toluene 4.5 part by weight, isopropyl alcohol (IPA) 0.4 part by weight

[Evaluation]
The laminates obtained in Examples 1 to 4 and Comparative Example 1 were subjected to a solvent wiping test and initial peel strength evaluation.

(1) Solvent wiping test Using a waste impregnated with IPA, an operation of wiping the surface of the antifouling layer of the laminate with a load of 500 g was performed 5 times. The antistatic property, haze and total light transmittance before and after the solvent wiping were measured by the following methods.

(I) Antistatic property It evaluated by measuring the surface specific resistance value of the antifouling layer of a laminated body. The surface specific resistance value was measured by using a digital insulation meter (Mitsubishi Chemical Co., Ltd. product: Lorestar GP MCP-T610) in accordance with JIS K7194.
(Ii) Haze The laminate was measured using an integrating sphere turbidimeter (NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K-7136.
(Iii) Total light transmittance The laminate was measured according to JIS K-7361 using an integrating sphere turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000). These results are shown in Table 2.

  As shown in Table 2, in Examples 1 to 4, the antistatic property is ensured even after the wiping test with IPA, and the solvent resistance to alcohol solvents is improved. It was confirmed that it was excellent. On the other hand, in Comparative Example 1, the antistatic property was completely lost after the wiping test with IPA. Although the comparative example 1 uses the same quaternary ammonium salt as a conventional antistatic agent, it was confirmed that it does not have solvent resistance to alcohol solvents. Further, no significant changes were observed in haze and total light transmittance.

(2) Initial peel strength evaluation After the obtained laminate is cut into a strip-shaped test piece having a width of 25 mm and a length of 150 mm, it has an acrylic pressure-sensitive adhesive under conditions in accordance with the standard of JIS Z0237. An adhesive tape (polyester adhesive tape No. 31B manufactured by Nitto Denko Corporation) was attached to the test piece. Thereafter, the peel strength was measured when the adhesive tape was peeled in the length direction of the test piece under the conditions of a peel angle of 180 °, a peel speed of 300 mm / min, and room temperature. A universal testing machine 5565 manufactured by Instron was used for the peel strength measurement. These results are shown in Table 3.

  As shown in Table 3, the laminates obtained in Examples 1 to 4 exhibited good peelability. Moreover, the comparative example 1 was also a favorable result about peelability.

It is a schematic sectional drawing which shows an example of the protective film of this invention. It is a side view which shows the winding-up state of the protective film shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base film 2 ... Antifouling layer 3 ... Adhesion layer

Claims (6)

  A base film, an antifouling layer formed on one surface of the base film and containing a boron-based antistatic agent and a release agent, and an adhesive layer formed on the other surface of the base film; The protective film characterized by having. 2. The protective film according to claim 1, wherein a surface specific resistance value of the antifouling layer is 1.0 × 10 ⁹ Ω / □ or less. When a solvent wiping test for wiping the surface of the antifouling layer with a waste impregnated with isopropyl alcohol was performed, the surface intrinsic value of the antifouling layer after the solvent wiping test was 1.0 × 10 ¹¹ Ω. The protective film according to claim 1, which is / □ or less.   4. The protective film according to claim 1, wherein the antifouling layer has a thickness in a range of 0.50 μm to 1.50 μm.   The protective film according to any one of claims 1 to 4, wherein the release agent is a polymer having a long-chain alkyl. It is a coating solution for forming a protective layer used to form a stain prevention layer of a protective film,
A coating liquid for forming an antifouling layer, comprising a boron antistatic agent and a release agent.

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