JP2011063712A - Surface protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface protective film inhibiting the generation of static electricity itself on peeling and capable of inhibiting the soiling of an adherend by peeling electrostatic charge and the generation of hindrance caused by spark, etc., by the peeling electrostatic charge, even in the cases of applying the surface protective film on a hard coat treatment by using a fluorine-containing compound or silicon-containing compound, or on a functional layer formed by a low reflection treatment or an anti-fouling treatment as the adherend. <P>SOLUTION: This surface protective film pasted on the adherend by taking the functional layer formed by the treatment using the fluorine-containing compound or silicon-containing compound as the adherend is provided by having an adhesive layer formed on the substrate film surface and at least adding an antistatic agent and >0.005 and <5 pts.mass range compound containing fluorine or silicon in its structure from outside based on 100 pts.mass acrylic adhesive, to the acrylic adhesive constituting the adhesive layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a surface protective film having excellent antistatic properties even on an adherend having a functional layer provided on the surface thereof, and less adherend adherent contamination.

  In recent years, in the flat panel display field, there has been a demand for improvement in water resistance and oil resistance in touch panel displays, as well as surface reflection prevention, antifouling suitability, and scratch resistance in liquid crystal displays and plasma displays applied to large-sized televisions and the like. Due to demand, products having functional layers laminated on the surface are increasing. For example, a polarizing plate provided with a hard coat (HC) layer coated with a fluorine-containing compound or a silicon-containing compound on its surface, an antireflection (Anti Reflection: AR) film provided with a low reflection layer, and a low reflection layer And an anti-glare treatment (AG; anti-glare treatment) AGLR (Anti Glare Low Reflection) polarizing plate, etc., which are appropriately selected according to the purpose and are widely used. More specifically, for example, in the case of touch panel applications, a hard coat layer is provided to prevent scratches on the panel surface. At the same time, fluorine-containing compounds and silicon-containing compounds are added for the purpose of water resistance and fingerprint adhesion reduction (antifouling). The thing provided with the coating film containing is widely used. Further, the AR film has both reflectance reduction and antifouling properties, and is used for, for example, a front filter of a plasma display.

  For the purpose of preventing scratches and contamination of the surface portion on which these functional layers are provided, which may occur in the manufacturing, transportation and sales processes of these products, In addition, a surface protective film (adhesive film) coated with a releasable adhesive is widely applied on the body. The surface protection film is easily and integrally peeled off from the adherend (product) during use, etc., but static electricity is generated at the time of peeling, and the surface protection film and the adherend have opposite polarities. So-called peeling electrification, which is charged as the charge it has, occurs. This peeling charge not only causes dust in the air to cause contamination of the product, but depending on the use of the product, a failure such as a breakdown of the electronic circuit occurs due to a spark caused by the peeling charge. There is also danger. For this reason, the pressure-sensitive adhesive for the surface protective film is required to have a low antistatic function, particularly a low charged voltage (amount) when the protective film is peeled off. As a specific means, conventionally, an antistatic agent is applied to the surface of the base material on which the functional layer is provided, or an antistatic agent such as a surfactant, an alkali metal salt or an ionic liquid is used in the adhesive of the protective film. An agent is added. There is also a proposal for a method for adjusting the peel chargeability of an adhesive film and an adherend to a good state in an adhesive film composed of a base material layer and an adhesive layer (see Patent Document 1). That is, in this document, when a low molecular weight component that can change the charging order of the pressure-sensitive adhesive layer other than the pressure-sensitive adhesive agent is contained in the pressure-sensitive adhesive layer, the amount of addition is measured when the peel charge amount is measured according to JIS. If the charge amount of the adherend is adjusted to be 10 nC or less, a film having a small peeling charge generated when peeling is easily obtained.

JP 2003-147296 A

  However, although the above prior art is useful for verifying whether or not the target film exhibits good release chargeability, the release charge occurs due to the balance between the adherend (functional layer) and the pressure-sensitive adhesive layer. In order to obtain an optimum surface protection film for each of the adherends made of various materials, it is necessary to examine each adherend, and the optimum content to be contained in the adhesive layer of the surface protection film is required. It is not easy to configure. According to the study by the present inventors, in particular, a hard coat (HC) provided with a functional layer obtained by imparting functionality to the surface using a fluorine-containing compound or a silicon-containing compound, which has been frequently used in recent years. For adherends such as polarizing plates and the above-mentioned AR films and AGLR polarizing plates, conventional surface protection films cannot suppress the peeling charge to a low level, and are optimal for such adherends. Recognized that it was an urgent need to develop a surface protective film (adhesive film).

  Therefore, an object of the present invention is to provide a functional layer obtained by subjecting a surface protective film to a hard coat treatment using a fluorine-containing compound or a silicon-containing compound, or a functional layer subjected to a low reflection or antifouling treatment using these compounds. When applied to any adherend on the surface, generation of static electricity at the time of peeling can be suppressed, and contamination of the adherend due to peeling electrification, destruction of electronic circuits due to sparks caused by peeling charging, etc. An object of the present invention is to provide a surface protection film having a high practical value and capable of suppressing the occurrence of obstacles.

  Said subject is achieved by the following this invention. That is, the present invention provides a surface protective film to be adhered to a functional layer formed by treatment with a fluorine-containing compound or a silicon-containing compound, and is attached to the adherend. The acrylic adhesive that forms the adhesive layer has at least an antistatic agent and more than 0.005 parts by mass with respect to 100 parts by mass of the acrylic adhesive. Provided is a surface protective film characterized in that a compound containing fluorine or silicon is externally added to the structure in a range smaller than the mass part.

  Preferred forms include the following. The compound containing fluorine or silicon in the structure is selected from the group consisting of a polyether-modified polyorganosiloxane, a fluorine-containing alkyl group-containing fluorosurfactant, and an acrylic polymer containing fluorine or silicon in the structure. The surface protective film selected. The compound containing fluorine or silicon in the structure is in the range of 0.05 to 4 parts by mass with respect to 100 parts by mass of the acrylic adhesive, and the antistatic agent is 100 parts by mass of the acrylic adhesive. The surface protective film is externally added in the range of 0.1 to 3 parts by mass. The said surface protection film in which the said to-be-adhered body is formed in the surface of a polarizing plate.

  According to the present invention, the adherend to which the surface protective film is stuck is formed by, particularly, a hard coat treatment using a fluorine-containing compound or a silicon-containing compound, or a low reflection treatment or an antifouling treatment with these compounds. Even in the case of a functional layer, the occurrence of static electricity during peeling is suppressed, and adherence contamination due to peeling electrification, and the occurrence of failures such as destruction of electronic circuits due to sparks caused by peeling charging, etc. An excellent surface protective film that can be suppressed is provided. As a result, the high quality can be reliably protected without impairing the commercial value of the product provided with the surface protective film.

It is a schematic diagram of a peeling test. It is a figure which shows the result of an Example. It is a figure which shows the result of a comparative example. It is a figure which shows the result of an Example. It is a figure which shows the result of an Example and a comparative example.

  Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention. In particular, the present inventors provide a hard coat (HC) polarizing plate having a functional layer formed on the surface by treatment with a fluorine-containing compound or a silicon-containing compound, and imparts low reflectivity and antifouling properties. As a result of intensive studies on the optimum surface protective film applicable to both the AR polarizing plate and the AGLR polarizing plate, conventional surface protective films are insufficient for these adherends (functional layers). In this case, it was found that the generation of static electricity itself is not sufficiently reduced but rather increased. In the above case, the present inventors have explained why the amount of static electricity generated cannot be reduced, because the surface of the polarizing plate is covered with a fluorine compound or a silicon compound, so that the difference between the adherend and the adhesive in the charged column is widened. For this reason, it is considered that the amount of static electricity generated during peeling increased. In this case, for example, there is a method of keeping the peeling charge low by causing the pressure-sensitive adhesive layer to contain a surfactant or the like to bleed out to the interface between the pressure-sensitive adhesive and the adherend. However, in this method, it is necessary to add a large amount of a surfactant to the pressure-sensitive adhesive layer, but this is not an appropriate method because it causes a decrease in peeling force and serious adherend contamination after peeling.

  On the other hand, the present inventors may add a pressure-sensitive adhesive layer constituting a surface protective film to an acrylic pressure-sensitive adhesive, an antistatic agent, and further add a compound having fluorine or silicon in its structure. In the present invention, the functional layer treated with a fluorine-containing compound or silicon-containing compound on the surface is used as an adherend, and is found to be effective as a means for suppressing the generation of static electricity upon peeling. It came. More specifically, as a compound containing fluorine or silicon in the structure, polyether-modified polyorganosiloxane, fluorine-containing alkyl group-containing cationic surfactants, anionic surfactants, nonionic surfactants In addition, the inventors have found that it is effective to include an acrylic polymer containing fluorine or silicon in the structure in the pressure-sensitive adhesive layer.

  The present inventors consider the reason why the above-described excellent effect can be obtained by the configuration of the present invention as follows. That is, as a result of adding a compound having fluorine or silicon in its structure to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer and a fluorine-containing compound or silicon-containing compound that becomes an adherend are treated. This is considered to be because the difference in the charge train with the functional layer formed on the surface is reduced, and the amount of static electricity generated at the time of peeling can be suppressed. More specifically, in the charge row order, (plus charge) acrylic resin> silicon resin> fluorine resin (minus charge), the acrylic resin is plus in the peeling charge between the acrylic resin and the silicon resin, and the silicon resin Are negatively charged. On the other hand, in the peeling charging between the silicon resin and the fluororesin [for example, Teflon (registered trademark)], the silicon resin is positively charged and the fluororesin is negatively charged. Thus, the silicon resin is charged positively or negatively depending on the other party. For this reason, the inventors of the present invention could easily neutralize the generated charge by adding a compound having fluorine or silicon in the structure to the pressure-sensitive adhesive layer, and as a result, the peel charge could be lowered. I think that. In particular, when there is a substance to be peeled or a third substance located in the middle of the charge train of the substance to be peeled, it is considered that the peeling charge may be lowered, but the polyether preferably used in the present invention It is inferred that the same effect was exhibited by adding a modified polyorganosiloxane, a fluorine-containing alkyl group-containing fluorosurfactant, and an acrylic polymer containing fluorine or silicon in the structure. For the polarizing plate that has been subjected to AG treatment only, the addition of an antistatic agent alone can lower the peeling charge, and the conventional surface protective film can cope with it. For conventional hard coat (HC) polarizing plates equipped with a functional layer formed by imparting functionality to the surface using a fluorine-containing compound or silicon-containing compound, the conventional surface protective film peels off. This is consistent with the fact that the charge could not be kept low. That is, the present invention uses a functional layer formed by treatment with a fluorine-containing compound or a silicon-containing compound, which has been insufficient for conventional surface protective film products, as an adherend, and is applied to the adherend. It is particularly useful as a surface protective film for the purpose.

  According to the study by the present inventors, in particular, acrylic pressure-sensitive adhesives, polyether-modified polyorganosiloxane, fluorine-containing alkyl group-containing cationic, anionic and nonionic fluorine-based surfactants, etc. It was found that by forming a pressure-sensitive adhesive layer in combination with an antistatic agent, static electricity generated at the time of peeling is quickly eliminated and a more excellent antistatic effect is exhibited. Based on the above reasoning, when a compound having fluorine or silicon in its structure is added to the pressure-sensitive adhesive layer, it has the effect of reducing the amount of static electricity generated (but is effective in neutralizing the generated charge). On the other hand, the addition of an antistatic agent such as an ionic liquid is considered to work effectively to neutralize a small amount of generated charge. In the case of the above-described functional layer that is an adherend to be used in the present invention, the amount of static electricity generated is too large, and the amount of common antistatic agent added exceeds the charge neutralization ability, which is a conventional protection. It is considered that the film was not able to keep the peeling charge low. On the other hand, increasing the addition amount of the antistatic agent causes another problem of adherend contamination, and is not an effective solution.

  According to the study by the present inventors, among them, it is preferable to add a compound containing fluorine in the structure rather than a compound containing silicon in the structure because a more balanced effect is obtained. . In addition, according to the configuration of the present invention, since the amount of the additive used as a whole can be reduced, there is little decrease in peeling force that may occur due to the inclusion of the additive, and there is very little contamination of the adherend. I understood. If contamination of the adherend can be reduced, the commercial value of the adherend after peeling will not be lowered. In addition, if the decrease in the peel force can be reduced, for example, even in the panel manufacturing process, even if the punching, pressurizing and heating processes are performed, the protective film will not be lifted or peeled off, so the product will be protected more reliably. be able to.

  Further, according to the study by the present inventors, in particular, the acrylic pressure-sensitive adhesive is configured such that an acrylic polymer containing fluorine or silicon in its structure, such as a fluoroalkyl group-containing acrylic polymer, is added. For example, the following effects can be obtained in addition to reducing the difference between the charged columns of the adherend and the adhesive and suppressing the amount of static electricity generated. Since the additive and the polymer serving as the base of the pressure-sensitive adhesive layer are both blends of acrylic components, it is possible to reduce opacification of the coating film due to poor compatibility and migration to the interface. Furthermore, if necessary, a fluoroalkyl group-containing acrylic polymer or the like is provided with a functional group and crosslinked with a curing agent, so that the reduction of adherend contamination can be further greatly improved. Also in this case, since the decrease in the peeling force is small, a surface protective film having a good peeling balance can be obtained. Further, as described above, if the adherend contamination can be reduced, the commercial value of the adherend after peeling will not be lowered. Furthermore, if the decrease in the peel force can be reduced, for example, even if the panel manufacturing process is performed by removing, pressing and heating, the protective film will not be lifted or peeled off, so the product can be protected more reliably. be able to.

  A base polymer that is a material for forming the pressure-sensitive adhesive layer constituting the surface protective film of the present invention, a compound added to this, a compound having fluorine or silicon in its structure, an antistatic agent, and a curing used as necessary The agent (crosslinking agent) will be described.

(Base polymer)
In the present invention, an acrylic resin is used as the base polymer of the pressure-sensitive adhesive. An acrylic copolymer suitable for the present invention includes a monomer including an acrylic monomer having an alkylene oxide group (hereinafter referred to as an AO group-containing monomer) and an acrylic monomer having a hydroxyl group (hereinafter referred to as an OH group-containing monomer). It can be obtained by appropriately selecting and copolymerizing. For example, content of 1 to 50% of the AO group-containing monomer in the total monomer in used in the reaction, more preferably 5-20%, the content of the OH group-containing monomer is about 0.1 to 10%, more preferably Is preferably copolymerized at a mass ratio of 0.5 to 5%.

  More specifically, a (meth) acrylic acid ester having 1 to 18 side chain carbon atoms and a (meth) acrylic acid ester having an alkylene oxide group and a hydroxyl group-containing (meth) acrylic acid ester monomer are included. In the above range to obtain a copolymer. Specific monomers that can be used in the above are not particularly limited, and examples thereof include lauryl methacrylate (LMA), 2-propylheptyl acrylate (2PHA), 2-ethylhexyl acrylate (2EHA), and butyl acrylate (BA). , Ethyl acrylate (EA), methyl acrylate (MA), # 400 methoxy polyethylene glycol monomethacrylate [MPEGMM (# 400)], # 200 methoxy polyethylene glycol monoacrylate [MPEGMA (# 200)], 2-hydroxyethyl acrylate (2HEA ), 4-hydroxybutyl methacrylate (4HBA), and can be used in appropriate combination.

  The base polymer (acrylic copolymer) can be produced, for example, as follows. In a reactor equipped with a reflux condenser, 75 to 90 parts by mass of a (meth) acrylic acid ester having 1 to 18 side chain carbon atoms, 5 to 20 parts by mass of an AO group-containing monomer, and 2 to 5 of an OH group-containing monomer. It can be easily obtained by adding an organic solvent and a polymerization initiator such as azobisisobutyronitrile to parts by mass and reacting for several hours at the reflux temperature of the organic solvent while stirring.

(Additive)
Examples of the compound containing fluorine or silicon in the structure to be added to the above base polymer characterizing the present invention include the following. For example, polyether-modified polyorganosiloxanes, of the fluorine-containing alkyl group, cationic, anionic, nonionic, can be used each fluorine-based surfactants. As commercially available products, KF-6011, KF-6012, KF-6015, KF-6017, X-22-3939A, X-22, which are polyether-modified polyorganosiloxanes having a polyether chain in the side chain. -4741, KF-1002 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.) and polyether modified polyorganosiloxanes having polyether chains at both ends, X-22-4952, X-22-4272, X -22-6266 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.).

上記式（１）中のＲ²、Ｒ⁴、Ｒ⁵は、アルキレン基であり、ｎは１〜１００の整数、ａおよびｂはそれぞれ０〜１００の整数である。 In the present invention, a compound comprising an organopolysiloxane having a structure represented by the following formula (1) or (2) can also be suitably used.

R ² , R ⁴ and R ⁵ in the above formula (1) are alkylene groups, n is an integer of 1 to 100, and a and b are integers of 0 to 100, respectively.

上記式（２）中の、Ｒ¹は１価の有機基、Ｒ²〜Ｒ⁴はアルキレン基、Ｒ⁵は水素又は１価の有機基、ｍは０〜１００の整数、ｎは１〜１００の整数、ａおよびｂはそれぞれ０〜１００の整数である。

Of the above formula (2), R ¹ represents a monovalent organic group, R ² to R ⁴ is an alkylene group, R ⁵ is hydrogen or a monovalent organic group, m is an integer of 0 to 100, n represents 1 to 100 , A and b are each an integer of 0 to 100.

  Nonionic fluorine-containing compounds include perfluoroalkyl group / hydrophilic group / lipophilic group-containing oligomers, Megafuck 477, Megafuck 470, Megafuck 444, Megafuck 445 (trade name: above, manufactured by DIC Corporation) Etc. Examples of the anion-type fluorine-containing compound include MegaFac 410 (trade name: manufactured by DIC Corporation), which is a carboxylic acid containing a perfluoroalkyl group, a hydrophilic group, and a lipophilic group.

  Fluorosurfactants include, for example, Footent 222F [trade name: polyoxyethylene type (nonionic)] having a perfluoroalkenyl group developed from a hexafluoropropene oligomer, and Footgent 310 [trade name: (Trimethyl {3- {4- [3,4,4,4-tetrafluoro-2- (perfluoroisopropyl) -1,3-bis (trifluoromethyl) -1-butenyloxy] benzoylamino} propyl} ammonium iodide (Cationic type)], and further 100 [trade name: (perfluoroalkenyl (C = 3, 9) oxybenzene sulfonate (Na, K)], 110 [trade name: (4-perfluorohexenyl). Sodium oxybenzenesulfonate) (anionic)] Is. Above are both made of Corporation Neos.

  The amount of these compounds to be added varies depending on the amount of the antistatic agent added to the adhesive, but is more than 0.005 parts by mass with respect to 100 parts by mass of the acrylic adhesive in the adhesive. The range is less than 5 parts by mass. More preferably, it may be externally added in the range of 0.05 to 3 parts by mass, and further in the range of 0.1 to 3 parts by mass. If the content is increased, the peeling force may be reduced to cause adherend contamination, which is not preferable. According to the study by the present inventors, the effect of the present invention is not sufficiently observed when the amount is extremely too small, 0.005 parts by mass or less, but 0.1 to 3 parts by mass, and further 0.1 to 1. A sufficient effect can be obtained with a small amount of about 0 part by mass. Moreover, what is necessary is just to perform the addition to the adhesive layer of these compounds by the following methods. For example, the above-described compound and an organic solvent such as an antistatic agent and toluene described later are added to and mixed with the base polymer obtained as described above. In this case, an acrylic copolymer composition solution having a viscosity at 25 ° C. of 3,000 to 5,000 mPa · s and a solid content of about 34 to 36% can be obtained. The pressure-sensitive adhesive composition used in the present invention Is obtained by appropriately adjusting properties such as adhesiveness by adding a curing agent (crosslinking agent) and a curing retarder as described later to this solution and mixing them well.

  Furthermore, in the present invention, an acrylic polymer containing fluorine or silicon in the structure may be used as a compound containing fluorine or silicon in the structure to be added to the base polymer (acrylic copolymer). it can. Such a polymer has good compatibility with the base polymer, and can be mixed in a good state in the pressure-sensitive adhesive layer to exert the effects of the present invention. Specifically, (meth) acrylic acid ester having a fluoroalkyl group in its structure, (meth) acrylic acid ester having silicon in its structure, etc., as a monomer used when synthesizing the above base polymer It is possible to use a polymer containing fluorine or silicon obtained by adding the above fluorine-containing or silicon-containing monomer. Examples of the monomer containing fluorine or silicon in the structure used in the present invention include the following.

  For example, trifluoroethyl (meth) acrylate, tetrafluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, nonafluorobutyl (meth) acrylate, octafluoropentyl (meth) acrylate, pentadecafluorooctyl (meth) acrylate Fluoroalkyl (meth) acrylates such as perfluorolauryl (meth) acrylate, tridecafluorohexylethyl (meth) acrylate, heptadecafluorooctylethyl (meth) acrylate, perfluorolaurylethyl (meth) acrylate, etc. it can.

  In addition, α-fluoro-ω- [2-((meth) acryloyloxy) ethyl] polydifluoromethylene, 2- [N-methyl-N- (perfluoro-n-alkylsulfonyl) amino] ethyl (meth) acrylate, etc. Fluorine-containing hydrophilic nonions or anionic monomers can be used.

  Also, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3 -(Meth) acryloxyalkylsilanes such as acryloxypropyltrimethoxysilane can be used.

  The amount of these fluorine-containing or silicon-containing monomers in the total monomer used when synthesizing a polymer containing fluorine or silicon is 1 to 99%, more preferably 5 to 90%, in mass ratio. At this time, a (meth) acrylic acid ester having 1 to 18 side chain carbon atoms may be added to the above as a base. Further, in addition to such a base monomer, for example, the AO group-containing monomer is about 1 to 80%, more preferably 5 to 50%, and the OH group-containing monomer is about 0.1 to 50%, more preferably. You may synthesize | combine using it by the mass ratio which will be 1-30%. As the AO group-containing monomer and the OH group-containing monomer, any of those mentioned in the description of the base polymer can be used.

  An acrylic polymer containing fluorine or silicon in its structure can be obtained by the same method as the base polymer described above, but in this case, an organic solvent is not used, and a polymerization chain is used if necessary. It is produced by adding a transfer agent and polymerizing while refluxing at a temperature of around 80 ° C. After the reaction, the polymer obtained by cooling to room temperature is obtained with a viscosity at 25 ° C. of 50,000 to 200,000 mPa · s and a solid content of about 99%, and this is added to the aforementioned base polymer. Is preferred. The average molecular weight is preferably about 1,000 to 100,000. The amount of the acrylic polymer containing fluorine or silicon in its structure varies depending on the amount of the antistatic agent added together, but is 0.1 to 5 on a mass basis in the pressure-sensitive adhesive. It is good to make it contain in about%, More preferably in 0.5 to 3% of range. The method for adding an acrylic polymer containing fluorine or silicon in its structure to the base polymer is preferably as follows. First, after synthesizing both of them, an antistatic agent and an organic solvent are added to the synthesized base polymer, and then cooled, an acrylic system containing fluorine or silicon is added to a solution having a viscosity of about 3,000 mPa · s. Add polymer and stir well to make uniform solution. Then, the adhesive composition used in the present invention can be obtained by adding a curing agent (crosslinking agent) and a curing retarder as described later to this solution and mixing them as necessary.

(Antistatic agent)
As the antistatic agent used in the present invention, any of metal salts, organic salts such as ionic liquids, and the like conventionally used for the purpose of reducing peeling charge can be used. In the present invention, since an antistatic agent is used particularly in order to quickly neutralize the bias of charge generated by peeling charging, a material having high electrical conductivity is preferable. Specifically, the antistatic agent used in the present invention preferably has an electrical conductivity value of 0.1 mS / cm or more. Any of the organic salts listed below has an electrical conductivity value of 0.1 mS / cm or more, and all are suitable for the present invention.

  Examples of the metal salt that can be used in the present invention include lithium = trifluoromethanesulfonate, lithium = bis (fluorosulfonyl) imide, lithium = bis (trifluoromethylsulfonyl) imide, lithium = bis (pentafluoroethylsulfonyl) imide, and the like. The thing containing these fluorine is mentioned. Organic salts include 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, 1-octylpyridinium bis (fluorosulfonyl) imide, N, N, N-trimethyl-N-propylammonium bis (Trifluoromethanesulfonyl) imide, N-methyl-N-propylpiperidinium = bis (fluorosulfonyl) imide, 3-methylpyrazolium = bis (pentafluoroethylsulfonyl) imide, trimethylsulfonium = bis (fluorosulfonyl) imide 1-hexyl-2,3-dimethylimidazolium bis (trifluoromethanesulfonyl) imide, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium bis (trifluoromethanesulfonyl) imide, -Butyl Lidinium = tetrafluoroborate, 1-butylpyridinium = bis (trifluoromethanesulfonyl) imide, 1-hexylpyridinium = bis (fluorosulfonyl) imide, 1-octylpyridinium = bis (fluorosulfonyl) imide, 4-methyl-1-octyl Pyridinium = bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium = hexafluorophosphate, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium bromide, 1 -Butyl-2,3-dimethylimidazolium = bis (pentafluoroethylsulfonyl) imide and the like. The amount of these antistatic agents added depends on the amount of the compound containing fluorine or silicon in the structure described above, which is added together with the antistatic agent, but with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive. The external addition may be in the range of 0.1 to 3 parts by mass, more preferably in the range of about 0.1 to 2 parts by mass.

(Curing agent)
Pressure-sensitive adhesive layer to characterize the surface protective film of the present invention, in addition to the above, and further a curing agent (crosslinking agent) may be formed so as to crosslink the part. If it does in this way, the adhesiveness and peelability of an adhesive layer will be improved, and the problem of the adherend contamination which arises when peeling a surface protection film can be improved more significantly. As the curing agent used in this case, any of isocyanate, epoxy, aziridine, melamine, metal and the like can be used. Specifically, Duranate TPA-100 (trade name: hexamethylene diisocyanate polyisocyanate, manufactured by Asahi Kasei Chemicals), Duranate T4330-75B (trade name: hexamethylene diisocyanate / isophorone diisocyanate = 70/30, manufactured by Asahi Kasei Chemicals), etc. Can be used. As addition amount of these hardening | curing agents, it is good to make it contain in the adhesive composition in about 0.1 to 5% by mass reference | standard, More preferably, it is 0.5 to 3% of range. In this case, the cured (crosslinked) state may be appropriately adjusted by blending a curing retarder such as acetylacetone in combination.

(Creation of surface protective film)
The surface protective film of the present invention can be prepared by the following method using a pressure-sensitive adhesive composition comprising the above components. First, a plastic film such as polyester, polyethylene, polypropylene and vinyl chloride is prepared as a base material. The thickness of the substrate is usually about 40 μm. The pressure-sensitive adhesive composition is directly applied to such a film using a bar coater or the like so that the pressure-sensitive adhesive layer thickness is about 25 μm. After drying this at a temperature of about 90 ° C. for about 60 seconds to form a pressure-sensitive adhesive layer, on the obtained pressure-sensitive adhesive layer, from a plastic film such as polyester having one surface water-repellent treated with a silicone coat or the like. The surface protection film of this invention is obtained by coat | covering the separator which becomes. The surface protective film of the present invention, especially if the addition of the curing agent or the like, in this state for several days, after curing, if to apply the product, becomes a more stable effect can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. In the following description, “parts” and “%” are based on mass unless otherwise specified.

<Example 1>
Using a reactor equipped with a stirrer, thermometer, reflux condenser and nitrogen introduction tube, after nitrogen gas was sealed, 75 parts of ethyl acetate, 15 parts of acetone, 80 parts of 2-ethylhexyl acrylate, # 400 methoxy were charged in the reaction vessel. 20 parts of polyethylene glycol monomethacrylate, 2 parts of 2-hydroxyethyl acrylate, and 0.2 part of a polymerization initiator (azobisisobutyronitrile) were charged. Next, it was made to react at the reflux temperature of a solvent for 7 hours, stirring with a stirrer. After completion of the reaction, 0.1 part of granol 100 (trade name: polyether modified polyorganosiloxane of AO terminal hydroxyl group type, manufactured by Kyoeisha Chemical Co., Ltd.) which is a silicon-containing compound, and lithium bis (trifluoromethylsulfonyl) as an antistatic agent 0.3 parts of imide and 95 parts of toluene are added and mixed, the mixture is cooled to room temperature, and a copolymer composition solution A having a viscosity at 30 ° C. of 3,000 mPa · s and a solid content of 30% is obtained. Obtained.

  Duranate TPA-100 (trade name: hexamethylene diisocyanate = isocyanurate type cross-linking agent, manufactured by Asahi Kasei Chemicals) as a curing agent (cross-linking agent) with respect to 100 parts of the solid content of the copolymer composition solution A obtained above. 2 parts and 2 parts of acetylacetone were added and mixed well to obtain an adhesive composition.

  The pressure-sensitive adhesive composition was directly applied to a 38 μm-thick polyester film as a substrate using a bar coater so that the pressure-sensitive adhesive layer thickness was 25 μm. Thereafter, after drying at 90 ° C. for 60 seconds to form an adhesive layer, the adhesive layer was coated with a 38 μm thick polyester film separator coated with silicone to produce a surface protective film of this example. Furthermore, the surface protective film obtained above was cured for 7 days in 23 ° C. and 50% RH, and used as a sample for each evaluation test.

<Examples 2 to 5>
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the types and composition ratios of the monomer, silicon-containing compound and antistatic agent used in Example 1 were changed as shown in Table 1. It was. And the surface protection film of Examples 2-5 was obtained by the method similar to Example 1 using each obtained adhesive composition.

<Comparative Examples 1-5>
The type and composition ratio of the monomers used in Example 1 were changed as shown in Table 2, and as shown in Table 2, an adhesive composition containing either a silicon-containing compound or an antistatic agent was prepared. I got each. And the surface protection film of Comparative Examples 1-4 was obtained by the method similar to Example 1 using each obtained adhesive composition. Comparative Examples 1 and 2 have a configuration in which only an antistatic agent is added, and Comparative Examples 3 and 4 have a configuration in which only a silicon-containing compound is added. Also, give none of the silicon-containing compound and an antistatic agent does not contain the pressure-sensitive adhesive composition and used to obtain a surface protective film of Comparative Example 5 in the same manner as in Example 1.

<Evaluation method>
Using HC polarizing plates hard-coated with a fluorine-based hard coat agent as adherends, the surface protective films of the examples and comparative examples obtained above were applied to these surfaces, and then peeled as follows. The force and peel voltage were measured respectively. The same applies to the AG polarizing plate whose surface is not coated with a fluorine-based hard coat agent. In addition, although the polarizing plate which performed only such AG process has a functional layer, even if only an antistatic agent is added, peeling electrification can be lowered to some extent. That is, the present invention is particularly useful as a surface protective film having a functional layer formed by treatment with a fluorine-containing compound or a silicon-containing compound, which was insufficient with a conventional surface protective film, as an adherend. It is.

  The effect of reducing the stripping voltage was examined by using a polytetrafluoroethylene (hereinafter referred to as PTFE) plate for the adherend so as to be easily confirmed. According to the study by the present inventors, it was confirmed that the PTFE plate had a higher peeling band voltage than the polarizing plate having a surface treated with a fluorine compound, but both showed a good correlation. Therefore, if a good result is obtained with a PTFE plate, it can be concluded that a polarizing plate whose surface is treated with a fluorine compound is also good. Moreover, after sticking on each polarizing plate, the contamination state of the adherend when peeled off was examined and evaluated. Furthermore, the surface resistance of the pressure-sensitive adhesive surface was measured. Detailed methods are as follows.

[Peeling force]
(1) Low-speed peeling force Each surface protection film obtained previously is bonded to the surface of each functional layer of the above-described AG polarizing plate and HC polarizing plate and the PTFE plate by one reciprocation with 2 kgf rollers, After 24 hours from the pasting, the low-speed peel force was measured using a Tensilon tensile tester RTG-1210 (trade name: manufactured by A & D). The measurement conditions are as follows. The measurement results are shown in Tables 1 and 2.
・ Tensile speed: 0.3 m / min
・ Peeling direction: 180 °
・ Sample size: 25mm x 100mm

(2) High-speed peeling force Each surface protection film obtained above is bonded to the surface of each functional layer of the above-described AG polarizing plate and HC polarizing plate and the PTFE plate by reciprocating each with 2 kgf rollers, After 24 hours from the pasting, the high speed peel force was measured using a high speed peel tester (manufactured by Tester Sangyo). The measurement conditions are as follows. The measurement results are shown in Tables 1 and 2.
・ Tensile speed: 30 m / min
・ Peeling direction: 180 °
・ Sample size: 25mm × 200mm

[Peeling voltage]
24 hours after pasting each surface protective film obtained above by pressing and reciprocating each 2 kgf roller on the surface of each functional layer of the AG polarizing plate and HC polarizing plate and the PTFE plate. After the elapse of time, the film is peeled off using a high speed peel tester (manufactured by Tester Sangyo). Then, the amount of static electricity generated at that time was measured with high precision electrostatic sensor SK-200, SK-030 (trade name: manufactured by Keyence Corporation). FIG. 1 is a schematic diagram showing a measurement state. A is the pressure-sensitive adhesive layer formed on the surface of the base film B, which is the side to be affixed to the protective film. C denotes a film having a functional layer provided on the surface of the adherend, E is a glass plate, D is the adhesive used for fixing the C and E, F is an aluminum plate It is. G indicates an electrostatic sensor. The conditions for peeling are as follows.
・ Tensile speed: 30 m / min
・ Peeling direction: 180 °
-Sample size: A4 (210 mm x 297 mm)

  The measurement results are shown in Tables 1 and 2, and the evaluation of the stripping voltage was shown by the maximum value and the minimum value of the generated static electricity. The measurement results are shown in FIGS. In the measurement method described above, the amount of static electricity of the adhesive applied to the protective film is measured until the protective film to be measured is peeled off, and the protective film is peeled off and falls out of the measurement range of the electrostatic sensor G. After that, the amount of static electricity of the remaining adherend will be measured. If the protective film is positively charged, the adherend should be negatively charged with the same size, but in the HC polarizing plate and PTFE plate treated with the fluorine-based surface treating agent examined above, If the opponent is acrylic, it is expected to be negatively charged. On the other hand, as shown in FIGS. 2 and 3, the actual measurement result is almost the same.

[Adherent contamination]
On the surface of the functional layer side of the above-mentioned AG polarizing plate and HC polarizer was bonded and pressed to the surface protective film obtained earlier in each 2kgf roller one round trip. And these samples are left to stand for 3 days in 70 degreeC environment. Thereafter, the sample was taken out and allowed to stand at 23 ° C. and 50% RH for 24 hours, and then the sample was peeled off from the adherend, and the degree of contamination was visually observed and evaluated according to the following criteria. The measurement results are shown in Tables 1 and 2.
○: No contamination is observed △: Slight contamination is observed ×: Contamination is observed

[Surface resistance value]
The surface resistance value of the adhesive surface of each surface protective film was measured using a high resistivity meter MCP-HT450 (trade name: manufactured by Mitsubishi Chemical Corporation). The measurement results are shown in Tables 1 and 2.

<Result 1>
As a result of comparing Table 1 and Table 2, the following points were found. The peel strength of the adhesive itself can be seen from the data of Comparative Example 5. The peel strength when only the antistatic agent is added to the pressure-sensitive adhesive is only slightly reduced if the addition amount is at this level, based on a comparison between the data of Comparative Example 1 or 2 and the data of Comparative Example 5. I understand. Comparing Comparative Example 3 in which a small amount of a nonionic fluorosurfactant was added to the case of Comparative Example 5, since Comparative Example 3 was added in a small amount, the adherend was not contaminated and the peeling force was slightly reduced. Although there is no effect of suppressing the stripping voltage. On the other hand, in Comparative Example 4 in which the amount of addition was very large, the peeling band voltage for the Teflon (registered trademark) plate and the HC polarizing plate was low, but the peeling force was considerably reduced and the adherend was contaminated. . From these facts, it can be seen that the additive amount is optimum when it is more than 0.005 parts and less than 5.0 parts.

  From the comparison of the results of Examples 1 to 5 and the results of Comparative Example 1 or 2 shown in Tables 1 and 2 and FIGS. 2 and 3, the following was confirmed. In the examples in which an appropriate amount of a compound containing fluorine or silicon is contained in the structure in addition to the antistatic agent, the surface of the pressure-sensitive adhesive layer is more than in the comparative example in which only the antistatic agent is added. The resistance value could be reduced. Furthermore, the peeling voltage was very low when peeling from any adherend, confirming that the generation of static electricity was reduced. Further, the decrease in peel strength remained at the same level or slightly inferior to that when only the antistatic agent was added, and did not affect the adherend contamination.

  The difference due to the compound containing fluorine or silicon in the structure as an additive was considered. As a result, in the case of the example in which the compound containing fluorine in Examples 3 to 5 was added, the peeling band voltage was the same or slightly inferior to the example in which the compound containing silicon in Examples 1 and 2 was added. However, it was confirmed that the degree of decrease in peeling force was small, while the surface resistance value became smaller, the generation of static electricity itself could be reduced, and a balanced effect was obtained.

<Example 6>
Using a reactor equipped with a stirrer, thermometer, reflux condenser and nitrogen introduction tube, after nitrogen gas was sealed, 75 parts of ethyl acetate, 15 parts of acetone, 73 parts of 2-ethylhexyl acrylate, 20 parts of butyl acrylate were added to the reaction vessel. Part, 7 parts of # 400 methoxypolyethylene glycol monomethacrylate, 3 parts of 4-hydroxyethyl acrylate and 0.2 part of a polymerization initiator (azobisisobutyronitrile) were charged. Next, it was made to react at the reflux temperature of a solvent for 7 hours, stirring with a stirrer. After completion of the reaction, 1.0 parts of lithium = bis (trifluoromethylsulfonyl) imide as an antistatic agent, and 95 parts of toluene were added and mixed, the mixture was cooled to room temperature, the viscosity at 30 ° C. is 3, A copolymer composition solution A-1 having a solid content of 35% was obtained.

  On the other hand, a polymer for additives was synthesized as follows. A reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube was used. After nitrogen gas was sealed, 47.5 parts of 2-ethylhexyl acrylate and 47.5 parts of # 400 methoxypolyethylene glycol monomethacrylate were placed in the reaction vessel. Part, light ester FM-108 [trade name: 2- (perfluorooctyl) ethyl methacrylate, manufactured by Kyoeisha Chemical Co., Ltd.], 3 parts triglycol dimercaptan and polymerization initiator V-65 (trade name: [2,2 0.02 part of '-Azobis (2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.] was added, and the reaction was continued for 7 hours while maintaining the temperature at 80 ° C. while stirring with a stirrer. The copolymer composition solution B-1 having a viscosity at 30 ° C. of 70,000 mPa · s and a solid content of 99% was obtained.

  2 parts of the copolymer composition solution B-1 was added to 100 parts of the solid content of the copolymer composition solution A-1 obtained previously and mixed well. As a crosslinking agent, 2 parts of Duranate TPA-100 (hexamethylene diisocyanate = isocyanurate type crosslinking agent) manufactured by Asahi Kasei Chemicals Co., Ltd. as a crosslinking agent with respect to 100 parts of the solid content of the copolymer composition solution obtained above, and acetylacetone 2 parts was added and mixed well to obtain an adhesive composition.

  The pressure-sensitive adhesive composition was directly applied to a 38 μm-thick polyester film as a substrate using a bar coater so that the pressure-sensitive adhesive layer thickness was 25 μm. Thereafter, after drying at 90 ° C. for 60 seconds to form an adhesive layer, the adhesive layer was coated with a 38 μm thick polyester film separator coated with silicone to produce a surface protective film of this example. Furthermore, the surface protection film obtained above was cured for 7 days in 23 ° C. and 50% RH, and used as a sample for each evaluation test. The evaluation was performed by measuring each of the peeling force, the peeling band voltage, and the surface resistance in the same manner as in Example 1. The evaluation results are shown in Table 5.

<Synthesis of polymers used in Examples 7-12 and Comparative Examples 6-8>
(1) Synthesis of copolymer composition solution A-2 The monomer composition was 90 parts of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 2 parts of 2-hydroxyethyl acrylate, and 1-octylpyridinium = except that bis (fluoro sulfonyl) imide was added 1.0 parts, in a similar manner to the copolymer composition solution a-1 prepared in example 6, to obtain a copolymer composition solution a-2 .

(2) a copolymer composition solution monomer composition of B-1 produced in Synthesis Example 6 of polymer additives, except that were changed as shown in Table 4, in each similar manner, copolycondensation Combined composition solutions B-2 to B-7 were synthesized.

<Examples 7 to 12 and Comparative Examples 6 to 8>
Copolymer composition solution A-1 or A-2 obtained above, the type shown copolymer composition is a polymer of additive solution B-2 to B-7, and a curing agent in Tables 5 Each pressure-sensitive adhesive composition was obtained in the same manner as in Example 6 except that it was used in an amount. And the surface protection film was produced by the method similar to having performed in Example 6 using the obtained adhesive composition. Furthermore, the obtained surface protective film was cured for 7 days at 23 ° C. and 50% RH, and it was evaluated in the same manner as in Example 6 as a sample for each evaluation test. The evaluation results are shown in Tables 5 and 6. .

<Result 2>
As a result of comparing Table 5 and Table 6, the following points can be understood. In the embodiment of adding an acrylic polymer having an antistatic agent and a fluorine-containing or silicon-containing pressure-sensitive adhesive, the peeling electrification voltage was confirmed that the much lower than the comparative examples do not. Furthermore, the surface resistance value of the pressure-sensitive adhesive layer was also reduced as compared with those not added, and it was confirmed that the generation of static electricity itself was reduced. Moreover, when the adherend contamination during the peel test was observed, no contamination was observed in any of the examples.

Claims (4)

  A functional protective layer formed by treatment with a fluorine-containing compound or a silicon-containing compound as an adherend, and a surface protective film to be attached to the adherend, the adhesive layer formed on the surface of the base film In the acrylic pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, at least the antistatic agent and the acrylic pressure-sensitive adhesive in an amount of more than 0.005 parts by mass and less than 5 parts by mass A surface protective film obtained by externally adding a compound containing fluorine or silicon in the structure.   The compound containing fluorine or silicon in the structure is any one of a polyether-modified polyorganosiloxane, a fluorine-containing alkyl group-containing fluorosurfactant, and an acrylic polymer containing fluorine or silicon in the structure. The surface protective film according to claim 1, selected from:   The compound containing fluorine or silicon in the structure is in a range of 0.05 to 3 parts by mass with respect to 100 parts by mass of the acrylic adhesive, and the antistatic agent is 100 parts by mass of the acrylic adhesive. The surface protective film according to claim 1, wherein the surface protective film is externally added in a range of 0.1 to 3 parts by mass with respect to parts.   The surface protection film according to claim 1, wherein the adherend is formed on a surface of a polarizing plate.

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