JP2016050254A - Antistatic surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antistatic surface protective film hardly causing staining on an adherend, not causing deterioration with time, and having excellent peeling antistatic performance.SOLUTION: An adhesive layer 2 made of an adhesive composition that comprises an acrylic polymer of copolymer including (A) at least one (meth)acrylic acid ester monomer including an alkyl group having 4-18 carbon atoms, and (B) at least one copolymerizable monomer containing a hydroxyl group, and not including a copolymerizable monomer containing a carboxyl group, and further contains (C) a bifunctional or more isocyanate compound, (D) a crosslinking accelerator, and (E) a keto-enol tautomeric compound is formed on one surface of a substrate film 1 made of a resin having transparency, and a release film 5 on which a release agent layer 4 is laminated is stuck on the surface of the adhesive layer 2. The release agent layer 4 comprises a release agent containing dimethylpolysiloxane as a main component and an antistatic agent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive composition and a surface protective film. More specifically, the present invention relates to an antistatic surface protective film having antistatic performance. More specifically, the present invention provides a method for producing an antistatic surface protective film that is less contaminated with respect to an adherend and has excellent peeling antistatic performance without deterioration over time, and an antistatic surface protective film.

When manufacturing and transporting optical products such as polarizing plates, retardation plates, lens films for displays, antireflection films, hard coat films, transparent conductive films for touch panels, and displays using the same. In this method, a surface protective film is bonded to the surface of the optical film to prevent the surface from being soiled or scratched in the subsequent step. The appearance inspection of the optical film, which is a product, may be performed while the surface protective film is bonded to the optical film in order to remove the trouble of bonding the surface protective film and increase the work efficiency again.
Conventionally, a surface protective film provided with a pressure-sensitive adhesive layer on one surface of a base film is generally used in order to prevent adhesion of scratches and dirt in the manufacturing process of optical products. The surface protective film is bonded to the optical film via a pressure-sensitive adhesive layer. The adhesive layer has a slight adhesive force because it can be easily removed when the used surface protection film is removed from the surface of the optical film and the adhesive is an adherend. This is to prevent the adhesive film from adhering and remaining on the optical film (preventing the occurrence of so-called adhesive residue).

In recent years, in the production process of a liquid crystal display panel, for controlling the display screen of the liquid crystal display panel by the peeling voltage generated when the surface protective film bonded on the optical film is peeled off and removed, A phenomenon in which circuit components such as driver ICs are destroyed and a phenomenon in which the orientation of liquid crystal molecules is damaged occur although the number of occurrences is small.
In addition, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material has been lowered, and along with this, the breakdown voltage of the driver IC has also been lowered. Recently, it has been required to set the peeling band voltage within the range of +0.7 kV to -0.7 kV.
Therefore, when the surface protective film is peeled off from the optical film as the adherend, an adhesive layer containing an antistatic agent for suppressing the peeling voltage is kept low in order to prevent problems caused by a high peeling voltage. A surface protective film using a material has been proposed.

For example, Patent Document 1 discloses a surface protective film using an adhesive made of an alkyltrimethylammonium salt, a hydroxyl group-containing acrylic polymer, and a polyisocyanate.
Patent Document 2 discloses a pressure-sensitive adhesive composition comprising an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and a pressure-sensitive adhesive sheet using the same.
Patent Document 3 discloses an adhesive composition composed of an alkali metal salt treated with an acrylic polymer, a polyether polyol compound, an anion adsorbing compound, and a surface protective film using the same.
Patent Document 4 discloses an adhesive composition comprising an ionic liquid, an alkali metal salt, a polymer having a glass transition temperature of 0 ° C. or less, and a surface protective film using the same.
Patent Documents 5 and 6 show that polyether-modified silicone is mixed in the pressure-sensitive adhesive layer of the surface protective film.

JP 2005-131957 A JP 2005-330464 A JP 2005-314476 A JP 2006-152235 A JP 2009-275128 A Japanese Patent No. 4537450

  In the above Patent Documents 1 to 4, an antistatic agent is added to the inside of the pressure-sensitive adhesive layer. However, as the thickness of the pressure-sensitive adhesive layer increases and the elapsed time passes, the surface protective film is bonded. The amount of the antistatic agent transferred from the pressure-sensitive adhesive layer to the adherend increases with respect to the adherend. In addition, in an optical film such as an LR (Low Reflective) polarizing plate or an AG (Anti Glare) -LR polarizing plate, the surface of the optical film is antifouling treated with a silicone compound or a fluorine compound. When the surface protective film used for such an optical film is peeled off from the optical film that is the adherend, the peeling voltage increases.

  In addition, when polyether-modified silicone is mixed in the pressure-sensitive adhesive layer described in Patent Documents 5 and 6, it is difficult to finely adjust the pressure-sensitive adhesive force of the surface protective film. In addition, since polyether-modified silicone is mixed in the pressure-sensitive adhesive layer, when the conditions for applying and drying the pressure-sensitive adhesive composition on the base film change, the pressure-sensitive adhesive layer on which the surface protective film is formed is changed. The surface characteristics change slightly. Furthermore, from the viewpoint of protecting the surface of the optical film, the thickness of the pressure-sensitive adhesive layer cannot be extremely reduced. Therefore, it is necessary to increase the amount of polyether-modified silicone added in the pressure-sensitive adhesive layer according to the thickness of the pressure-sensitive adhesive layer. As a result, the surface of the adherend is easily contaminated, and the adhesive strength over time is increased. Contamination to the adherend changes.

  In recent years, with the widespread use of 3D displays (stereoscopic displays), there are films in which an FPR (Film Patterned Retarder) film is bonded to the surface of an optical film such as a polarizing plate. After peeling off the surface protective film bonded to the surface of the optical film such as a polarizing plate, the FPR film is bonded. However, if the surface of an optical film such as a polarizing plate is contaminated with the pressure-sensitive adhesive or antistatic agent used in the surface protective film, there is a problem that the FPR film is difficult to adhere. For this reason, the surface protection film used for the said use is a thing with little contamination with respect to a to-be-adhered body.

  On the other hand, in some liquid crystal panel manufacturers, as a method for evaluating the contamination of the adherend of the surface protective film, the surface protective film bonded to the optical film such as a polarizing plate is peeled off once and air bubbles are mixed in. In this state, a method is employed in which the re-bonded material is heat-treated under predetermined conditions, and then the surface protective film is peeled off to observe the surface of the adherend. In such an evaluation method, even if the surface contamination of the adherend is very small, the difference in surface contamination of the adherend between the portion where the bubbles are mixed and the portion where the adhesive of the surface protection film is in contact If there is, it remains as a trace of bubbles (sometimes called bubble bubbles). Therefore, it is a very strict evaluation method as a method for evaluating the contamination on the surface of the adherend. In recent years, there has been a demand for a surface protective film that does not have a problem of contamination on the surface of an adherend even as a result of such strict evaluation. However, the surface protection film using the pressure-sensitive adhesive layer containing an antistatic agent, which has been proposed so far, is in a situation where it is difficult to solve the problem.

  For this reason, there is a need for a surface protective film used for an optical film, which has very little contamination on the adherend and whose contamination on the adherend does not change with time. Furthermore, there is a demand for a surface protective film that suppresses the peeling voltage when peeling from an adherend.

The present inventors diligently studied to solve this problem.
In order to reduce the contamination of the adherend and reduce the change in antistatic performance with time, it is necessary to reduce the addition amount of the antistatic agent that is presumed to be a cause of contamination of the adherend. However, when the addition amount of the antistatic agent is reduced, the peeling voltage when the surface protective film is peeled from the adherend becomes high. The inventors of the present invention have studied a method for suppressing the peeling voltage when the surface protective film is peeled off from the adherend without increasing the absolute amount of the antistatic agent added. As a result, instead of adding an antistatic agent to the pressure-sensitive adhesive composition to form a pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition is applied and dried to laminate the pressure-sensitive adhesive layer, It has been found that by applying an appropriate amount of an antistatic agent component to the surface of the layer, the peeling voltage can be kept low when the surface protective film is peeled off from the optical film as the adherend. Was completed.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an antistatic surface protective film that has less contamination to the adherend and has excellent anti-peeling performance without deterioration over time. And

  In order to solve the above problems, the antistatic surface protective film of the present invention is prepared by applying and drying an adhesive composition and laminating an adhesive layer, and then applying an appropriate amount of an antistatic agent to the surface of the adhesive layer. The technical idea is to suppress the contamination voltage with respect to the adherend to a low level and to suppress the peeling voltage when peeling from the optical film as the adherend.

In order to solve the above problems, the present invention is an antistatic surface protective film comprising the following steps (1) to (2):
Step (1): Monomer copolymerizable with at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms on one side of a base film made of a resin having transparency. As a group, it comprises an acrylic polymer of a copolymer containing no copolymerizable monomer containing a carboxyl group, but containing (B) at least one copolymerizable monomer containing a hydroxyl group, C) forming a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing a bifunctional or higher functional isocyanate compound, (D) a crosslinking accelerator, and (E) a ketoenol tautomer compound;
Step (2): a step of bonding a release film in which a release agent layer containing an antistatic agent is laminated on one surface of the resin film on the surface of the pressure-sensitive adhesive layer via the release agent layer;
The release agent layer is formed of a resin composition containing a release agent mainly composed of dimethylpolysiloxane and an antistatic agent, and the release voltage of the adhesive layer is ± Provided is an antistatic surface protective film characterized by being 0.6 kV or less.

  In addition, the copolymerizable monomer group preferably further includes (F) a polyalkylene glycol mono (meth) acrylate monomer.

  Further, the (D) crosslinking accelerator is at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound, and 100 parts by weight of the acrylic polymer of the copolymer 0.001 to 0.5 parts by weight with respect to the above (E) 0.1 to 300 parts by weight of the ketoenol tautomer compound, and the weight of (E) / (D) The part ratio is preferably 70 to 1000.

  Further, the copolymerizable monomer (B) containing a hydroxyl group may be 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) ) At least one selected from the group consisting of acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide, It is preferable that it is 0.1-10 weight part with respect to 100 weight part of acrylic polymers.

  In addition, the copolymerizable monomer group further includes (F) a polyalkylene glycol mono (meth) acrylate monomer, or (F) a polyalkylene glycol mono (meth) acrylate monomer. At least one selected from the group consisting of polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate, and 100 wt. It is preferable that it is 0-50 weight part with respect to a part.

  In addition, as the (C) bifunctional or higher functional isocyanate compound, the bifunctional isocyanate compound is an acyclic aliphatic isocyanate compound, which is a compound formed by reacting a diisocyanate compound and a diol compound, Is an aliphatic diisocyanate, and one kind selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate, and diol compound as 2-methyl-1 , 3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propane Consisting of a compound selected from the group consisting of all, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, polypropylene glycol, 3 Examples of functional isocyanate compounds include isocyanurates of hexamethylene diisocyanate compounds, isocyanurates of isophorone diisocyanate compounds, adducts of hexamethylene diisocyanate compounds, adducts of isophorone diisocyanate compounds, burettes of hexamethylene diisocyanate compounds, and isophorone diisocyanate compounds. Burette body, isocyanurate body of tolylene diisocyanate compound, isocyanurate body of xylylene diisocyanate compound, hydrogenated An isocyanurate of a silylene diisocyanate compound, an adduct of a tolylene diisocyanate compound, an adduct of a xylylene diisocyanate compound, an adduct of a hydrogenated xylylene diisocyanate compound, and 100 parts by weight of the acrylic polymer of the copolymer. 0.1 to 10 parts by weight is preferable.

  In addition, (G) a polyether-modified siloxane compound having an HLB value of 7 to 15 is added to the pressure-sensitive adhesive composition in an amount of 1.0 part by weight or less (0 part by weight based on 100 parts by weight of the acrylic polymer of the copolymer). It is preferable to include it.

  The antistatic agent in the release agent layer is preferably an alkali metal salt.

Further, the antistatic agent in the release agent layer is a Li salt, and at least selected from a compound group consisting of Li (CF ₃ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, and LiCF ₃ SO ₃ One or more are preferred.

  Moreover, in order to solve said subject, this invention is the (meth) acrylic acid ester monomer whose carbon number of (A) alkyl group is C4-C18 on the single side | surface of the base film which consists of resin which has transparency. A copolymer containing at least one kind and a copolymerizable monomer group which does not contain a copolymerizable monomer containing a carboxyl group, but (B) at least one kind of copolymerizable monomer containing a hydroxyl group. A pressure-sensitive adhesive layer comprising an acrylic polymer and further comprising (C) a bifunctional or higher functional isocyanate compound, (D) a crosslinking accelerator, and (E) a ketoenol tautomer compound. A release film in which a release agent layer containing an antistatic agent is laminated on one surface of a resin film is attached to the surface of the pressure-sensitive adhesive layer via the release agent layer. Becomes Te Align, the release agent layer, provides a release agent composed mainly of dimethyl polysiloxane, an antistatic surface protecting film characterized by comprising formed of a resin composition containing an antistatic agent.

  In addition, the copolymerizable monomer group preferably further includes (F) a polyalkylene glycol mono (meth) acrylate monomer.

  In addition, (G) a polyether-modified siloxane compound having an HLB value of 7 to 15 is added to the pressure-sensitive adhesive composition in an amount of 1.0 part by weight or less (0 part by weight based on 100 parts by weight of the acrylic polymer of the copolymer). It is preferable to include it.

  The antistatic agent in the release agent layer is preferably an alkali metal salt.

Further, the antistatic agent in the release agent layer is a Li salt, and at least selected from a compound group consisting of Li (CF ₃ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, and LiCF ₃ SO ₃ One or more are preferred.

  Moreover, this invention provides the film for optics by which said antistatic surface protection film is bonded together.

  Moreover, this invention provides the optical component formed by bonding said antistatic surface protection film.

The antistatic surface protective film of the present invention has little contamination on the adherend, and the low contamination on the adherend does not change with time. Further, according to the present invention, even if the surface of an adherend such as an LR polarizing plate or an AG-LR polarizing plate is an optical film that has been subjected to antifouling treatment with a silicone compound, a fluorine compound, or the like, it is antistatic. It is possible to provide an antistatic surface protective film that can suppress a peeling voltage generated when the surface protective film is peeled from the adherend, and has excellent peeling antistatic performance without deterioration over time.
According to the antistatic surface protective film of the present invention, the surface of the optical film can be reliably protected, so that productivity and yield can be improved.

It is sectional drawing which showed the concept of the antistatic surface protection film of this invention. It is sectional drawing which shows the state which peeled off the peeling film from the antistatic surface protection film of this invention. It is sectional drawing which showed one of the Examples of the optical component of this invention.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is a sectional view showing the concept of the antistatic surface protective film of the present invention. The antistatic surface protective film 10 has a pressure-sensitive adhesive layer 2 formed on one surface of a transparent substrate film 1. A release film 5 having a release agent layer 4 formed on the surface of the resin film 3 is bonded to the surface of the pressure-sensitive adhesive layer 2.

As the base film 1 used for the antistatic surface protective film 10 according to the present invention, a base film made of a resin having transparency and flexibility is used. Thereby, the external appearance inspection of an optical component can be performed in the state which bonded the antistatic surface protection film to the optical component which is a to-be-adhered body. The film made of a resin having transparency used as the base film 1 is preferably a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate. In addition to the polyester film, a film made of another resin can be used as long as it has a required strength and optical suitability. The base film 1 may be an unstretched film or a uniaxially or biaxially stretched film. Moreover, you may control the draw ratio of a stretched film, and the orientation angle of the axial method formed with crystallization of a stretched film to a specific value.
The thickness of the base film 1 used for the antistatic surface protective film 10 according to the present invention is not particularly limited. For example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is easy to handle. More preferable.
Further, if necessary, an antifouling layer for preventing surface contamination, an antistatic layer, a hard coat layer for preventing scratches, etc. on the surface opposite to the surface on which the adhesive layer 2 of the base film 1 is formed. Can be provided. Further, the surface of the base film 1 may be subjected to easy adhesion treatment such as surface modification by corona discharge and application of an anchor coating agent.

  The pressure-sensitive adhesive layer 2 used in the antistatic surface protective film 10 according to the present invention is a pressure-sensitive adhesive that adheres to the surface of an adherend and can be easily peeled off after use and hardly contaminates the adherend. If it is not particularly limited, it is common to use an acrylic pressure-sensitive adhesive obtained by crosslinking a (meth) acrylate copolymer in consideration of durability after bonding to an optical film. .

In particular, the main component of the acrylic pressure-sensitive adhesive is a copolymer containing a carboxyl group as a monomer group copolymerizable with (A) at least one of (meth) acrylic acid ester monomers having an alkyl group of C4 to C18. A pressure-sensitive adhesive layer made of an acrylic polymer of a copolymer that does not contain a polymerizable monomer but contains (B) at least one copolymerizable monomer containing a hydroxyl group is preferred.
The copolymerizable monomer group may further include (F) polyalkylene glycol mono (meth) acrylate monomer.
Furthermore, in addition to the acrylic polymer, a pressure-sensitive adhesive composition comprising (C) a bifunctional or higher functional isocyanate compound, (D) a crosslinking accelerator, and (E) a ketoenol tautomer compound. An agent layer is preferred.

(A) As a (meth) acrylic acid ester monomer having an alkyl group with a carbon number of C4 to C18, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl ( (Meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl ( (Meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadec (Meth) acrylate, octadecyl (meth) acrylate, myristyl (meth) acrylate, isomyristyl (meth) acrylate, cetyl (meth) acrylate, isocetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, etc. Is mentioned.
When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, (A) the alkyl group has a C4-C18 (meth) acrylic acid ester monomer in a proportion of 50 to 95 parts by weight. Preferably it is.

(B) As a copolymerizable monomer containing a hydroxyl group, 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate And hydroxyalkyl (meth) acrylates such as N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and hydroxyl-containing (meth) acrylamides such as N-hydroxyethyl (meth) acrylamide.
8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meta It is preferably at least one selected from the group consisting of acrylamide and N-hydroxyethyl (meth) acrylamide.
When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, it is preferable that the copolymerizable monomer (B) containing a hydroxyl group is contained in a proportion of 0.1 to 10 parts by weight.

(C) The bifunctional or higher functional isocyanate compound may be at least one selected from polyisocyanate compounds having at least two or more isocyanate (NCO) groups in one molecule. Polyisocyanate compounds are classified into aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, and alicyclic isocyanates, and any of them may be used. Specific examples of the polyisocyanate compound include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI). And aromatic isocyanate compounds such as hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylene diisocyanate (TOID), and tolylene diisocyanate (TDI).
As trifunctional or higher functional isocyanate compounds, trifunctional or higher valences of bifunctional isocyanate compounds (compounds having two NCO groups in one molecule) such as burette modified products and isocyanurate modified products, trimethylolpropane (TMP) and glycerin are used. And adduct bodies (polyol-modified bodies) with polyols (compounds having at least 3 or more OH groups in one molecule).
(C) It is also possible to use only the (C-1) trifunctional isocyanate compound or the (C-2) bifunctional isocyanate compound as the bifunctional or higher functional isocyanate compound. Moreover, it is also possible to use together (C-1) trifunctional isocyanate compound and (C-2) bifunctional isocyanate compound.

  Furthermore, as the (C-1) trifunctional isocyanate compound used in the present invention, an isocyanurate body of a hexamethylene diisocyanate compound, an isocyanurate body of an isophorone diisocyanate compound, an adduct body of a hexamethylene diisocyanate compound, an adduct body of an isophorone diisocyanate compound, At least one selected from the group of (C-1-1) first aliphatic isocyanate compounds, consisting of a burette of hexamethylene diisocyanate compound and a burette of isophorone diisocyanate compound, and a tolylene diisocyanate compound Isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, tolylene diisocyanate Selected from the group (C-1-2) second aromatic isocyanate compound group consisting of an adduct of a compound, an adduct of a xylylene diisocyanate compound, and an adduct of a hydrogenated xylylene diisocyanate compound, It is preferable to contain at least one or more. It is preferable to use together the (C-1-1) first aliphatic isocyanate compound group and the (C-1-2) second aromatic isocyanate compound group. In the present invention, as the (C-1) trifunctional isocyanate compound, (C-1-1) at least one selected from the first aliphatic isocyanate compound group, and (C-1-2) ) By using in combination with at least one selected from the group of the second aromatic isocyanate compounds, the balance of the adhesive force in the low-speed peeling region and the high-speed peeling region can be further improved.

  The (C-1) trifunctional isocyanate compound may be at least one selected from the group (C-1-1) of the first aliphatic isocyanate compound group, and the (C-1-2). ) At least one selected from the group of second aromatic isocyanate compounds, and a total of 0.5 to 5.0 with respect to 100 parts by weight of the acrylic polymer of the copolymer. It is preferable that a part by weight is contained. Also, (C-1-1) at least one selected from the first aliphatic isocyanate compound group and (C-1-2) the second aromatic isocyanate compound group. The mixing ratio with at least one or more selected from (C-1-1) :( C-1-2) is within a range of 10%: 90% to 90%: 10% by weight. Is preferred.

Furthermore, the (C-2) bifunctional isocyanate compound used in the present invention is preferably a compound produced by reacting a diisocyanate compound and a diol compound with an acyclic aliphatic isocyanate compound.
For example, the diisocyanate compound represented by the general formula “O═C═N—X—N═C═O” (where X is a divalent group), the general formula “HO—Y—OH” (where Y is a divalent group). ) Represents a compound represented by the following general formula Z, for example, as a compound produced by reacting a diisocyanate compound with a diol compound.

[General formula Z]
O═C═N—X— (NH—CO—O—Y—O—CO—NH—X) _n —N═C═O

  Here, n is an integer of 0 or more. When n is 0, the general formula Z represents “O═C═N—X—N═C═O”. As the bifunctional acyclic aliphatic isocyanate compound, a compound in which n is 0 in the general formula Z (an unreacted diisocyanate compound with respect to the diol compound) may be included, but a compound in which n is an integer of 1 or more is an essential component. It is preferable to include as. The bifunctional acyclic aliphatic isocyanate compound may be a mixture composed of a plurality of compounds having different n in the general formula Z.

  The diisocyanate compound represented by the general formula “O═C═N—X—N═C═O” is an aliphatic diisocyanate. X is preferably an acyclic and aliphatic divalent group. The aliphatic diisocyanate is preferably one or more selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

  The diol compound represented by the general formula “HO—Y—OH” is an aliphatic diol. Y is preferably an acyclic and aliphatic divalent group. Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2-ethyl-2. -From the compound group consisting of butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, polypropylene glycol It is preferable that it consists of 1 type or 2 types or more selected.

  The weight ratio (C-1 / C-2) between the (C-1) trifunctional isocyanate compound and the (C-2) bifunctional isocyanate compound is preferably 1 to 90. The (C) bifunctional or higher isocyanate compound is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer of the copolymer.

  (D) The crosslinking accelerator may be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent when a polyisocyanate compound is used as the crosslinking agent. An amine compound such as an organic metal compound, an organic metal compound such as an organic tin compound, an organic lead compound, and an organic zinc compound. In the present invention, a metal chelate compound or an organic tin compound is preferable as the crosslinking accelerator.

The metal chelate compound is a compound in which one or more multidentate ligands L are bonded to the central metal atom M. The metal chelate compound may or may not have one or more monodentate ligands X bonded to the metal atom M. For example, when the general formula of a metal chelate compound having one metal atom M is represented by M (L) _m (X) _n , m ≧ 1 and n ≧ 0. When m is 2 or more, the m Ls may be the same ligand or different ligands. When n is 2 or more, the n Xs may be the same ligand or different ligands.

Examples of the metal atom M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, and Sn.
As the polydentate ligand L, β-ketoester such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, acetylacetone (also known as 2,4-pentanedione), Examples include β-diketones such as 2,4-hexanedione and benzoylacetone. These are ketoenol tautomeric compounds, and the polydentate ligand L may be an enolate (for example, acetylacetonate) in which enol is deprotonated.
As monodentate ligand X, acyloxy such as halogen atom such as chlorine atom and bromine atom, pentanoyl group, hexanoyl group, 2-ethylhexanoyl group, octanoyl group, nonanoyl group, decanoyl group, dodecanoyl group and octadecanoyl group Group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, alkoxy group such as butoxy group, and the like.

  Specific examples of the metal chelate compound include tris (2,4-pentanedionato) iron (III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum tris Acetylacetonate, zirconium tetrakisacetylacetonate, tris (2,4-hexanedionate) iron (III), bis (2,4-hexanedionate) zinc, tris (2,4-hexanedionate) titanium, tris (2,4-Hexanedionato) aluminum, tetrakis (2,4-hexanedionato) zirconium and the like can be mentioned.

Examples of the organic tin compound include dialkyl tin oxide, fatty acid salt of dialkyl tin, fatty acid salt of stannous and the like. Conventionally, many dibutyltin compounds have been used. Recently, however, the problem of toxicity of organic tin compounds has been pointed out, and in particular, tributyltin (TBT) contained in dibutyltin compounds is also a concern as an endocrine disrupting substance. From the viewpoint of safety, long-chain alkyl tin compounds such as dioctyl tin compounds are preferred. Specific examples of the organic tin compound include dioctyl tin oxide and dioctyl tin dilaurate. Temporarily, Sn compounds can also be used, but in the future, in view of the demand for the use of safer substances, such as Al, Ti, Fe, etc., which are safer than Sn. It is preferable to use a metal chelate compound.
(D) The crosslinking accelerator in the pressure-sensitive adhesive composition according to the present invention is preferably at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound and an iron chelate compound.
(D) It is preferable that a crosslinking accelerator is contained 0.001-0.5 weight part with respect to 100 weight part of acrylic polymers of a copolymer.

(E) Ketoenol tautomeric compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, acetylacetone, 2,4-hexanedione And β-diketones such as benzoylacetone. In the pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, by blocking the isocyanate group of the cross-linking agent, excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after blending of the cross-linking agent are suppressed. The pot life of the pressure-sensitive adhesive composition can be extended.
(E) It is preferable that 0.1-300 weight part of keto enol tautomer compound is contained with respect to 100 weight part of acrylic polymers of a copolymer.

  Since the (E) ketoenol tautomer compound has an effect of suppressing crosslinking, as opposed to the (D) crosslinking accelerator, the ratio of the (E) ketoenol tautomer compound to the (D) crosslinking accelerator. Is preferably set appropriately. In order to increase the pot life of the pressure-sensitive adhesive composition and improve the storage stability, it is preferable that the ratio by weight of (E) / (D) is 70 to 1000.

The acrylic polymer can further optionally contain (F) a polyalkylene glycol mono (meth) acrylate monomer as the copolymerizable monomer group. The (F) polyalkylene glycol mono (meth) acrylate monomer may be a compound in which one hydroxyl group is esterified as a (meth) acrylate ester among a plurality of hydroxyl groups of the polyalkylene glycol. Since the (meth) acrylic acid ester group becomes a polymerizable group, it can be copolymerized with the main polymer. The other hydroxyl group may be OH or may be an alkyl ether such as methyl ether or ethyl ether, or a saturated carboxylic acid ester such as acetate.
Examples of the alkylene group of the polyalkylene glycol include, but are not limited to, an ethylene group, a propylene group, and a butylene group. The polyalkylene glycol may be a copolymer of two or more polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Examples of the polyalkylene glycol copolymer include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol, and the copolymer includes: It may be a block copolymer or a random copolymer.
(F) It is preferable that the polyalkylene glycol mono (meth) acrylic acid ester monomer has an average number of repeating alkylene oxides constituting the polyalkylene glycol chain of 3 to 14. The “average number of repeating alkylene oxides” is the average number of repeating alkylene oxide units in the “polyalkylene glycol chain” part of the molecular structure of the (F) polyalkylene glycol mono (meth) acrylate monomer. is there.

(F) As polyalkylene glycol mono (meth) acrylate monomer, selected from polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (meth) acrylate, ethoxy polyalkylene glycol (meth) acrylate, It is preferable that it is at least one or more.
More specifically, polyethylene glycol-mono (meth) acrylate, polypropylene glycol-mono (meth) acrylate, polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polypropylene glycol-mono (meth) acrylate, polyethylene glycol-poly Butylene glycol-mono (meth) acrylate, polypropylene glycol-polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polypropylene glycol-polybutylene glycol-mono (meth) acrylate; methoxypolyethylene glycol- (meth) acrylate, methoxypolypropylene glycol -(Meth) acrylate, methoxypolybutylene glycol- (meth) acrylate, methoxy Polyethylene glycol-polypropylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, methoxy-polypropylene glycol-polybutylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol -(Meth) acrylate; ethoxy polyethylene glycol- (meth) acrylate, ethoxy polypropylene glycol- (meth) acrylate, ethoxypolybutylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polypropylene glycol- (meth) acrylate, ethoxy-polyethylene Glycol-polybutylene glycol- (meth) acrylate Ethoxy - polypropylene glycol - polybutylene glycol - (meth) acrylate, ethoxy - polyethylene glycol - polypropylene glycol - polybutylene glycol - such as (meth) acrylate.
When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, it is preferable that the (F) polyalkylene glycol mono (meth) acrylate monomer is contained in a proportion of 0 to 50 parts by weight. In the pressure-sensitive adhesive layer according to the present invention, the pressure-sensitive adhesive composition may not contain (F) polyalkylene glycol mono (meth) acrylate monomer.

The pressure-sensitive adhesive composition can optionally contain (G) a polyether-modified siloxane compound having an HLB value of 7 to 15. The polyether-modified siloxane compound is a siloxane compound having a polyether group. In addition to a normal siloxane unit [—SiR ¹ ₂ —O—], a siloxane unit having a polyether group [—SiR ¹ (R ² O ( having _{^{R 3 O) n R 4)}} -O- ]. Here, R ¹ is one or more alkyl groups or aryl groups, R ² and R ³ are one or more alkylene groups, and R ⁴ is one or more alkyl groups or acyl groups. Etc. (terminal group). Examples of the polyether group include polyoxyalkylene groups such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] and a polyoxypropylene group [(C ₃ H ₆ O) _n ].

The polyether-modified siloxane compound is preferably a (G) polyether-modified siloxane compound having an HLB value of 7 to 15. Moreover, it is preferable that 0.01-1.0 weight part of polyether modified siloxane compounds whose (G) HLB value is 7-15 are contained with respect to 100 weight part of acrylic polymers of a copolymer. More preferably, it is 0.1-0.5 weight part.
HLB is a hydrophilic / lipophilic balance (hydrophilic / lipophilic ratio) defined in, for example, JIS K3211 (surfactant term).

The polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a silicon hydride group by a hydrosilylation reaction. Specifically, dimethylsiloxane-methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane-methyl (polyoxyethylene) siloxane-methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane-methyl (polyoxypropylene) Examples thereof include siloxane polymers. The HLB value of the polyether-modified siloxane compound can be adjusted by selecting the ratio between the polyether group and the siloxane group.
(G) The adhesive force and rework performance of an adhesive can be improved by mix | blending the polyether modified siloxane compound whose HLB value is 7-15 with an adhesive composition. When the pressure-sensitive adhesive composition does not contain a polyether-modified siloxane compound, the cost becomes lower.

  Further, as other components, copolymerizable (meth) acrylic monomer containing alkylene oxide, (meth) acrylamide monomer, dialkyl-substituted acrylamide monomer, surfactant, curing accelerator, plasticizer, filler, curing retarder, Known additives such as processing aids, anti-aging agents, and antioxidants can be appropriately blended. These may be used alone or in combination of two or more.

The copolymer of the main agent used in the pressure-sensitive adhesive composition of the present invention is a monomer group that can be copolymerized with (A) at least one of (meth) acrylic acid ester monomers having an alkyl group of C4 to C18. However, it can be synthesized by copolymerizing (B) at least one copolymerizable monomer containing a hydroxyl group, but not containing a copolymerizable monomer containing a carboxyl group. The copolymerizable monomer group may further contain (F) polyalkylene glycol mono (meth) acrylate monomer. The polymerization method of the copolymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.
The pressure-sensitive adhesive composition of the present invention comprises (C) a bifunctional or higher isocyanate compound, (D) a crosslinking accelerator, (E) a ketoenol tautomer compound, and any appropriate additive. It can prepare by mix | blending.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth) acrylic acid ester monomer, (meth) acrylic acid, or (meth) acrylamide.
Since the acrylic polymer does not contain a copolymerizable monomer containing a carboxyl group as a copolymerizable monomer group, it is effective in improving the crosslinking rate and stabilizing the adhesive force. As the monomer that reacts with the (C) bifunctional or higher functional isocyanate compound used as the crosslinking agent, it is preferable to use a copolymerizable monomer (B) containing a hydroxyl group. Preferred monomer compositions of the copolymer include one or more types from (A) and (B), one or more types from (A), (B), and (F), respectively. Can be mentioned.

  The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition has an adhesive strength of 0.05 to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min, and a high speed peeling speed of 30 m / min. The adhesive strength is preferably 1.0 N / 25 mm or less. Thereby, the performance with little change in the adhesive force depending on the peeling speed can be obtained, and it is possible to peel quickly even by high speed peeling. In addition, when the surface protective film is once peeled off for re-sticking, excessive force is not required and it is easy to peel off from the adherend.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition preferably has a surface resistivity of 5.0 × 10 ⁺¹² Ω / □ or less and a peeling voltage of “± 0.6 kV or less”. In the present invention, “± 0.6 kV or less” means 0 to −0.6 kV and 0 to +0.6 kV, that is, −0.6 to +0.6 kV. If the surface resistivity is large, the performance of releasing static electricity generated by electrification at the time of peeling is inferior. Therefore, peeling caused by static electricity generated when the adherend peels off the adhesive layer by sufficiently reducing the surface resistivity. The charged voltage is reduced, and it is possible to suppress the influence on the electric control circuit and the like of the adherend.

  The gel fraction of the pressure-sensitive adhesive layer (cross-linked pressure-sensitive adhesive) obtained by crosslinking the pressure-sensitive adhesive composition of the present invention is preferably 95 to 100%. Because of the high gel fraction, the adhesive force does not become excessive at a low peeling speed, and the elution of unpolymerized monomers or oligomers from the copolymer is reduced, resulting in reworkability and high temperature / high humidity. Durability is improved and contamination of the adherend can be suppressed.

  The pressure-sensitive adhesive film of the present invention is formed by forming a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present invention on one side or both sides of a resin film. Moreover, the surface protective film of this invention is a surface protective film formed by forming the adhesive layer formed by bridge | crosslinking the adhesive composition of this invention on the single side | surface of a resin film. In the pressure-sensitive adhesive composition of the present invention, the above components (A) to (E) are blended in a well-balanced manner, so that it has excellent antistatic performance, and at a low peeling speed and a high peeling speed, Excellent balance of adhesive strength, and also excellent durability and rework performance (no contamination transfer on the adherend after tracing the surface protection film with a ballpoint pen through the adhesive layer) Become. For this reason, it can be used suitably as a use of the surface protection film of a polarizing plate.

  The thickness of the pressure-sensitive adhesive layer 2 used in the antistatic surface protective film 10 according to the present invention is not particularly limited, but for example, a thickness of about 5 to 40 μm is preferable, and a thickness of about 10 to 30 μm is more preferable. From the adherend, the peel strength (adhesive strength) of the antistatic surface protective film to the surface of the adherend is about 0.03 to 0.3 N / 25 mm, and the pressure-sensitive adhesive layer 2 has a slight adhesive strength. It is preferable because it is excellent in operability when peeling off the antistatic surface protective film. Moreover, since it is excellent in the operativity at the time of peeling the peeling film 5 from the antistatic surface protection film 10, it is preferable that the peeling force from the adhesive layer 2 of the peeling film 5 is 0.2 N / 50mm or less.

  Moreover, the release film 5 used for the antistatic surface protective film 10 according to the present invention is a resin composition containing a release agent mainly composed of dimethylpolysiloxane and an antistatic agent on one side of the resin film 3. The release agent layer 4 used is formed.

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, and a polyimide film, and a polyester film is particularly preferable because of its excellent transparency and a relatively low price. . The resin film may be an unstretched film or a uniaxially or biaxially stretched film. Moreover, you may control the draw ratio of a stretched film, and the orientation angle of the axial method formed with crystallization of a stretched film to a specific value.
Although the thickness of the resin film 3 is not particularly limited, for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is more preferable because it is easy to handle.
Further, if necessary, the surface of the resin film 3 may be subjected to easy adhesion treatment such as surface modification by corona discharge or application of an anchor coating agent.

  Examples of the release agent mainly composed of dimethylpolysiloxane constituting the release agent layer 4 include known silicone release agents such as an addition reaction type, a condensation reaction type, a cationic polymerization type, and a radical polymerization type. Examples of products that are commercially available as addition reaction type silicone release agents include KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (manufactured by Shin-Etsu Chemical Co., Ltd.). SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Toray Dow Corning Co., Ltd.), and the like. Examples of products marketed as a condensation reaction type include SRX-290 and SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.). Examples of products marketed as a cationic polymerization type include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). ) And the like. Examples of the product marketed as a radical polymerization type include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

  The antistatic agent constituting the release agent layer 4 has good dispersibility in a release agent solution mainly composed of dimethylpolysiloxane and inhibits curing of the release agent mainly composed of dimethylpolysiloxane. Those that do not are preferred. As such an antistatic agent, an alkali metal salt is suitable.

Examples of the alkali metal salt include metal salts composed of lithium, sodium, and potassium. Specifically, for example, a cation composed of Li ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , A metal salt composed of an anion composed of (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ is preferable. Used for. Among these, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, lithium salt (Li salt) such as Li (CF ₃ SO ₂ ) ₃ C, in particular Li (CF ₃ SO ₂ ) ₂ N “abbreviation symbol LiTFSI”, Li (FSO ₂ ) ₂ N “abbreviation symbol LiFSI ", LiCF ₃ SO ₃ " abbreviated symbol LiTF or LiTf "is preferably used. These alkali metal salts may be used alone or in combination of two or more. In order to stabilize the ionic substance, a compound containing a polyoxyalkylene structure may be added.
The amount of antistatic agent added to the release agent based on dimethylpolysiloxane varies depending on the type of antistatic agent and the degree of affinity with the release agent, but when the antistatic surface protective film is peeled off from the adherend. These may be set in consideration of the desired stripping voltage, contamination to the adherend, adhesive properties, and the like.

  There is no particular limitation on the method of mixing the release agent mainly composed of dimethylpolysiloxane and the antistatic agent. A method of adding an antistatic agent to a release agent based on dimethylpolysiloxane and mixing and then adding and mixing a catalyst for curing the release agent. Method of adding and mixing antistatic agent and release agent curing catalyst after diluting with solvent, diluting release agent mainly composed of siloxane in organic solvent, adding and mixing catalyst, then antistatic agent Any method may be used, such as a method of adding and mixing. Moreover, you may add the material which assists the antistatic effect, such as adhesion improving agents, such as a silane coupling agent, and the compound containing a polyoxyalkylene group as needed.

  The mixing ratio of the release agent mainly comprising dimethylpolysiloxane and the antistatic agent is not particularly limited, but the antistatic agent is solid relative to the solid content 100 of the release agent mainly containing dimethylpolysiloxane. A ratio of about 5 to 100 is preferable as a minute. When the addition amount of the antistatic agent in terms of solid content is less than 5 to the solid content 100 of the release agent mainly composed of dimethylpolysiloxane, the transfer amount of the antistatic agent to the surface of the pressure-sensitive adhesive layer is also reduced. As a result, the antistatic function is hardly exhibited in the adhesive. Further, when the addition amount of the antistatic agent in terms of solid content exceeds 100 with respect to the solid content 100 of the release agent containing dimethylpolysiloxane as a main component, dimethylpolysiloxane is used as the main component together with the antistatic agent. Since the release agent is also transferred to the surface of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive properties of the pressure-sensitive adhesive may be reduced.

  The method for forming the pressure-sensitive adhesive layer 2 and the method for bonding the release film 5 to the base film 1 of the antistatic surface protective film 10 according to the present invention may be carried out by known methods, and are not particularly limited. Specifically, (1) A method of laminating the release film 5 after applying a resin composition for forming the pressure-sensitive adhesive layer 2 on one side of the base film 1 and drying to form a pressure-sensitive adhesive layer, (2) On the surface of the release film 5, after applying and drying the resin composition for forming the pressure-sensitive adhesive layer 2 to form the pressure-sensitive adhesive layer, a method of pasting the base film 1 can be mentioned. Any method may be used.

  Moreover, what is necessary is just to perform the adhesive layer 2 on the surface of the base film 1 by a well-known method. Specifically, known coating methods such as reverse coating, comma coating, gravure coating, slot die coating, Mayer bar coating, and air knife coating can be used.

  Similarly, the release agent layer 4 may be formed on the resin film 3 by a known method. Specifically, known coating methods such as gravure coating, Mayer bar coating, and air knife coating can be used.

FIG. 2 is a cross-sectional view showing a state where the release film is peeled off from the antistatic surface protective film of the present invention.
By removing the release film 5 from the antistatic surface protective film 10 shown in FIG. 1, a part of the antistatic agent (symbol 7) contained in the release agent layer 4 of the release film 5 is antistatic surface protective film. It is transferred (attached) to the surface of the ten pressure-sensitive adhesive layers 2. Therefore, in FIG. 2, the antistatic agent transferred to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protective film is schematically indicated by the reference numeral 7.
In the antistatic surface protective film according to the present invention, the antistatic surface protective film 11 with the release film shown in FIG. 2 peeled off is transferred to the surface of the pressure-sensitive adhesive layer 2 before being bonded to the adherend. In addition, the antistatic agent contacts the surface of the adherend. As a result, the stripping voltage when the antistatic surface protective film is peeled from the adherend again can be kept low.

FIG. 3 is a cross-sectional view showing an embodiment of the optical component of the present invention.
From the antistatic surface protective film 10 of the present invention, the release film 5 is peeled off and the pressure-sensitive adhesive layer 2 is exposed, and is bonded to the optical component 8 that is an adherend through the pressure-sensitive adhesive layer 2. The
That is, FIG. 3 shows an optical component 20 to which the antistatic surface protective film 10 of the present invention is bonded. Examples of the optical component include optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate that also serves as a retardation plate, and a polarizing plate that also serves as a lens film. Such an optical component is used as a constituent member of a liquid crystal display device such as a liquid crystal display panel and an optical system device of various instruments. Examples of the optical component include optical films such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel. In particular, anti-fouling of optical films such as a low reflection treatment polarizing plate (LR polarizing plate) and an anti-glare low reflection processing polarizing plate (AG-LR polarizing plate) whose surface is antifouling treated with a silicone compound or a fluorine compound. It can be suitably used as an antistatic surface protective film that is bonded to the contaminated surface.
According to the optical component of the present invention, when the antistatic surface protection film 10 is peeled off from the adherend optical component (optical film), the stripping voltage can be suppressed sufficiently low. There is no fear of destroying circuit components such as ICs, TFT elements, and gate line driving circuits, and the production efficiency in the process of manufacturing a liquid crystal display panel or the like can be increased and the reliability of the production process can be maintained.

  Next, the present invention will be further described with reference to examples.

<Manufacture of an adhesive composition>
[Example 1]
Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and the air in the reactor was replaced with nitrogen gas. Thereafter, 100 parts by weight of 2-ethylhexyl acrylate, 4.5 parts by weight of 8-hydroxyoctyl acrylate, 10 parts by weight of polypropylene glycol monoacrylate (n = 12) and 60 parts by weight of a solvent (ethyl acetate) were added to the reactor. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was dropped over 2 hours and reacted at 65 ° C. for 6 hours to obtain an acrylic copolymer solution of Example 1 having a weight average molecular weight of 500,000. Obtained. To this acrylic copolymer solution, 8.5 parts by weight of acetylacetone was added and stirred, and then 2.5 parts by weight of coronate HX (isocyanurate of hexamethylene diisocyanate compound) and 0.1% by weight of titanium trisacetylacetonate. The pressure-sensitive adhesive composition of Example 1 was obtained by adding parts and stirring and mixing.

[Examples 2-6 and Comparative Examples 1-3]
The pressure-sensitive adhesive compositions of Examples 2 to 6 and Comparative Examples 1 to 3 were the same as Example 1 except that the compositions of the pressure-sensitive adhesive compositions of Example 1 were as shown in Tables 1 and 2, respectively. I got a thing. In Tables 1 and 2, monomers included (copolymerized) in the acrylic copolymer are (A), (B), (F), and “carboxyl group-containing monomer”.

Tables 1 and 2 are obtained by dividing the integrated table showing the blending ratio of each component into two, and in both cases, the numerical values of parts by weight calculated with the total of group (A) as 100 parts by weight are enclosed in parentheses. It shows with. In addition, Table 3 and Table 4 show the names of the abbreviations of the components used in Tables 1 and 2. Coronate (registered trademark) HX, HL and L are trade names of Nippon Polyurethane Industry Co., Ltd., and Takenate (registered trade marks) D-140N, D-127N and D-110N are trade names of Mitsui Chemicals, Inc. It is. In “Antistatic Agent” in Table 2 and Table 7 described later, LiTFSI represents Li (CF ₃ SO ₂ ) ₂ N, LiFSI represents Li (FSO ₂ ) ₂ N, LiTF represents LiCF ₃ SO ₃ , and SH8400. Represents polyether-modified silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SH8400, main component: dimethyl, methyl (polyethylene oxide acetate) siloxane).

<Synthesis of bifunctional isocyanate compound>
The bifunctional isocyanate compounds of Synthesis Examples 1 and 2 were synthesized by the following method. As shown in Table 5 and Table 6, the diisocyanate and the diol compound were mixed at a molar ratio of NCO / OH = 16 and reacted at 120 ° C. for 3 hours, and then under reduced pressure using a thin film evaporator. Unreacted diisocyanate was removed to obtain the desired bifunctional isocyanate compound.

<Preparation of antistatic surface protective film>
[Example 1]
Addition reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345) 5 parts by weight, Li (CF ₃ SO ₂ ) ₂ N 0.5 part by weight, 1: 1 mixed solvent of toluene and ethyl acetate 95 parts by weight and platinum catalyst (Toray Dow Corning Co., Ltd., product name: SRX-212 Catalyst) 0.05 parts by weight are mixed, stirred and mixed to form the release agent layer of Example 1 Adjusted. The paint for forming the release agent layer of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm with a Mayer bar so that the thickness after drying was 0.2 μm, and a 120 ° C. hot-air circulating oven And dried for 1 minute to obtain a release film of Example 1.
The pressure-sensitive adhesive composition of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried in a hot air circulation oven at 100 ° C. for 2 minutes. Thus, an adhesive layer was formed. Then, the release agent layer (silicone treatment surface) of the release film of Example 1 produced above was bonded to the surface of this adhesive layer. The obtained pressure-sensitive adhesive film was kept warm at 40 ° C. for 5 days to cure the pressure-sensitive adhesive, and the antistatic surface protective film of Example 1 was obtained.

[Example 2]
Example 2 is the same as Example 1 except that the pressure-sensitive adhesive composition of Example 1 is changed to the pressure-sensitive adhesive composition of Example 2 and the antistatic agent used in the release agent layer is LiCF ₃ SO _3. An antistatic surface protective film was obtained.

[Examples 3 to 6]
The pressure-sensitive adhesive composition of Example 1 was changed to the pressure-sensitive adhesive composition of Examples 3 to 6, respectively, and the antistatic agent used in the release agent layer was Li (FSO ₂ ) ₂ N. Thus, antistatic surface protective films of Examples 3 to 6 were obtained.

[Comparative Example 1]
Addition reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345), 95 parts by weight of 1: 1 mixed solvent of toluene and ethyl acetate, and platinum catalyst (manufactured by Toray Dow Corning Co., Ltd.) (Product name: SRX-212 Catalyst) 0.05 parts by weight were mixed and stirred and mixed to prepare a coating material for forming the release agent layer of Comparative Example 1. A paint for forming the release agent layer of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm with a Mayer bar so that the thickness after drying was 0.2 μm, and a 120 ° C. hot air circulation oven And dried for 1 minute to obtain a release film of Comparative Example 1.
The pressure-sensitive adhesive composition of Comparative Example 1 was applied on the surface of a polyethylene terephthalate film having a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried in a hot air circulation oven at 100 ° C. for 2 minutes. Thus, an adhesive layer was formed. Thereafter, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1 prepared above was bonded to the surface of this pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive film was kept warm at 40 ° C. for 5 days to cure the pressure-sensitive adhesive, and the antistatic surface protective film of Comparative Example 1 was obtained.

[Comparative Example 2]
An antistatic surface protective film of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the pressure-sensitive adhesive composition of Comparative Example 1 was changed to the pressure-sensitive adhesive composition of Comparative Example 2.

[Comparative Example 3]
The pressure-sensitive adhesive composition of Example 1 was changed to the pressure-sensitive adhesive composition of Comparative Example 3, and the antistatic agent used in the release agent layer was changed to Li (FSO ₂ ) ₂ N. An antistatic surface protective film of Comparative Example 3 was obtained.

  Table 7 shows the composition of the release agent layer in the antistatic surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3.

<Test method and evaluation>
The surface protective films in Examples 1 to 6 and Comparative Examples 1 to 3 were aged in an atmosphere of 23 ° C. and 50% RH for 7 days, and then the release film (silicone resin-coated PET film) was peeled off. The material layer exposed was used as a sample for measuring surface resistivity.
Further, the surface protective film on which the pressure-sensitive adhesive layer was exposed was bonded to the surface of the polarizing plate attached to the liquid crystal cell via the pressure-sensitive adhesive layer, and allowed to stand for 1 day, then at 50 ° C., 5 atm, 20 minutes. What was autoclaved and allowed to stand at room temperature for another 12 hours was used as a sample for measuring adhesive strength, peeling band voltage, and reworkability.

<Adhesive strength>
The measurement sample obtained above (25 mm wide surface protective film bonded to the surface of the polarizing plate) was peeled at a low peeling speed (0.3 m / min) and high speed using a tensile tester in the 180 ° direction. The peel strength measured at the peel speed (30 m / min) was measured as the adhesive strength.

<Surface resistivity>
After aging, before bonding to the polarizing plate, peel off the release film (silicone resin-coated PET film) to expose the adhesive layer, and use a resistivity meter Hiresta UP-HT450 (manufactured by Mitsubishi Chemical Analytech) The surface resistivity of the pressure-sensitive adhesive layer was measured.

<Peeling voltage>
When the measurement sample obtained above is peeled 180 ° at a tensile speed of 30 m / min, the voltage (charge voltage) generated by charging the polarizing plate is measured with high-precision electrostatic sensors SK-035 and SK-200 (stocks). (Manufactured by Keyence Co., Ltd.), and the maximum value of the measured value was defined as the peeling voltage.

<Reworkability>
After the surface protective film of the measurement sample obtained above was traced with a ballpoint pen (load 500 g, 3 reciprocations), the surface protective film was peeled off from the polarizing plate, the surface of the polarizing plate was observed, and the polarizing plate was contaminated. Confirmed that there was no migration. Evaluation target criteria are “O” when there is no contamination transfer on the polarizing plate, “△” when contamination transfer is confirmed at least partially along the trace traced with the ballpoint pen, and along the trace traced with the ballpoint pen. The case where contamination transfer was confirmed and the release of the adhesive was also confirmed from the adhesive surface was evaluated as “x”.

Table 8 shows the evaluation results. The surface resistivity was expressed by a system in which “m × 10 ^{+ n} ” is “mE + n” (where m is an arbitrary real value and n is a positive integer).

From the measurement results shown in Table 8, the following can be understood.
The antistatic surface protective films of Examples 1 to 6 according to the present invention have moderate adhesive strength, no contamination to the surface of the adherend, and when the antistatic surface protective film is peeled off from the adherend. The peel voltage is low.
On the other hand, the antistatic surface protective film of Comparative Example 1 in which a silicone compound and an antistatic agent are added to the adhesive layer has a low surface resistivity of the adhesive layer and is good, but has a high adhesive force, so that the stripping voltage is High and inferior to reworkability. In Comparative Example 2, the pressure-sensitive adhesive gelled due to the large amount of the crosslinking accelerator added, and the coating could not be performed. Moreover, in the comparative example 3, since the monomer containing a carboxyl group was included, adhesive force was large and rework property was a little inferior.
That is, in Comparative Examples 1 and 2 in which a silicone compound and an antistatic agent are mixed in the pressure-sensitive adhesive, it is difficult to achieve both reduction of the stripping voltage and contamination to the adherend. On the other hand, in Examples 1 to 6, in which the antistatic agent was transferred to the surface of the pressure-sensitive adhesive layer after the antistatic agent was added to the release agent layer, there was an effect of reducing the peeling voltage with a small addition amount. A good antistatic surface protective film was obtained without contamination of the adherend.

The antistatic surface protective film of the present invention is, for example, a surface of the optical component in a production process of an optical film such as a polarizing plate, a retardation plate, a lens film for display, and other various optical components. Can be used to protect. In particular, when used as an antistatic surface protective film for an optical film such as an LR polarizing plate or an AG-LR polarizing plate, the surface of which is antifouling treated with a silicone compound or a fluorine compound. The amount of static electricity generated can be reduced.
The antistatic surface protective film of the present invention is less contaminated on the adherend, and further has excellent peeling antistatic performance without deterioration over time, so that the production process yield can be improved, and the industrial utility value Is big.

DESCRIPTION OF SYMBOLS 1 ... Base film, 2 ... Adhesive layer, 3 ... Resin film, 4 ... Release agent layer, 5 ... Release film, 7 ... Antistatic agent, 8 ... Adhering body (optical component), 10 ... Antistatic surface protection Film, 11 ... Antistatic surface protective film from which release film has been peeled off, 20 ... Optical component bonded with antistatic surface protective film.

Claims (16)

An antistatic surface protective film comprising the following steps (1) to (2):
Step (1): Monomer copolymerizable with at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms on one side of a base film made of a resin having transparency. As a group, it comprises an acrylic polymer of a copolymer containing no copolymerizable monomer containing a carboxyl group, but containing (B) at least one copolymerizable monomer containing a hydroxyl group, C) forming a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing a bifunctional or higher functional isocyanate compound, (D) a crosslinking accelerator, and (E) a ketoenol tautomer compound;
Step (2): a step of bonding a release film in which a release agent layer containing an antistatic agent is laminated on one surface of the resin film on the surface of the pressure-sensitive adhesive layer via the release agent layer;
Are made in order,
The release agent layer is formed of a resin composition containing a release agent mainly composed of dimethylpolysiloxane and an antistatic agent, and the release voltage of the adhesive layer is ± 0.6 kV or less. An antistatic surface protective film.   The antistatic surface protective film according to claim 1, further comprising (F) a polyalkylene glycol mono (meth) acrylate monomer as the copolymerizable monomer group.   The (D) crosslinking accelerator is at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound, and relative to 100 parts by weight of the acrylic polymer of the copolymer 0.001 to 0.5 parts by weight, 0.1 to 300 parts by weight of the (E) ketoenol tautomer compound, and (E) / (D) parts by weight ratio The antistatic surface protective film according to claim 1, wherein is from 70 to 1,000.   The copolymerizable monomer containing the (B) hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate. , N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and at least one selected from the group of compounds consisting of N-hydroxyethyl (meth) acrylamide, and the acrylic of the copolymer The antistatic surface protective film according to any one of claims 1 to 3, wherein the amount is 0.1 to 10 parts by weight with respect to 100 parts by weight of the polymer. The copolymerizable monomer group further includes (F) polyalkylene glycol mono (meth) acrylic acid ester monomer or not,
The (F) polyalkylene glycol mono (meth) acrylate monomer is selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol (meth) acrylate, The antistatic surface protective film according to claim 1, wherein the antistatic surface protective film is at least one kind and is 0 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer of the copolymer.   As the (C) bifunctional or higher functional isocyanate compound, the bifunctional isocyanate compound is an acyclic aliphatic isocyanate compound, which is a compound produced by reacting a diisocyanate compound and a diol compound. As the diisocyanate compound, An aliphatic diisocyanate, which is selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and diol compounds include 2-methyl-1,3 -Propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol A trifunctional compound selected from the group consisting of 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, and polypropylene glycol. Isocyanurates of hexamethylene diisocyanate compounds, isocyanurates of isophorone diisocyanate compounds, adducts of hexamethylene diisocyanate compounds, adducts of isophorone diisocyanate compounds, burettes of hexamethylene diisocyanate compounds, burettes of isophorone diisocyanate compounds , Isocyanurate of tolylene diisocyanate compound, isocyanurate of xylylene diisocyanate compound, hydrogenated xylylene A diisocyanate compound isocyanurate, an adduct of a tolylene diisocyanate compound, an adduct of a xylylene diisocyanate compound, an adduct of a hydrogenated xylylene diisocyanate compound, and 100 parts by weight of the acrylic polymer of the copolymer. The antistatic surface protective film according to claim 1, wherein the content is 0.1 to 10 parts by weight.   In the pressure-sensitive adhesive composition, (G) a polyether-modified siloxane compound having an HLB value of 7 to 15 is 1.0 part by weight or less (0 part by weight of 100 parts by weight of the acrylic polymer of the copolymer). The antistatic surface protective film according to any one of claims 1 to 6, further comprising:   The antistatic surface protective film according to claim 1, wherein the antistatic agent in the release agent layer is an alkali metal salt. The antistatic agent in the release agent layer is a Li salt, and at least one selected from the group consisting of Li (CF ₃ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, and LiCF ₃ SO _3. The antistatic surface protective film according to claim 1, wherein   On one side of a base film made of a resin having transparency, (A) a carboxyl group as a monomer group copolymerizable with at least one of (meth) acrylic acid ester monomers having an alkyl group of C4 to C18. And (B) at least one copolymerizable monomer containing a hydroxyl group, and (C) a bifunctional or higher functional polymer. The pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing an isocyanate compound of (D), a crosslinking accelerator, and (E) a ketoenol tautomer compound, is formed on the surface of the pressure-sensitive adhesive layer, A release film in which a release agent layer containing an antistatic agent is laminated on one side of a resin film is bonded to the release film through the release agent layer, A release agent composed mainly of Rokisan, antistatic surface protecting film characterized by comprising formed of a resin composition containing an antistatic agent.   The antistatic surface protective film according to claim 10, further comprising (F) a polyalkylene glycol mono (meth) acrylate monomer as the copolymerizable monomer group.   In the pressure-sensitive adhesive composition, (G) a polyether-modified siloxane compound having an HLB value of 7 to 15 is 1.0 part by weight or less (0 part by weight of 100 parts by weight of the acrylic polymer of the copolymer). The antistatic surface protective film according to claim 10, wherein the antistatic surface protective film is included.   The antistatic surface protective film according to claim 10, wherein the antistatic agent in the release agent layer is an alkali metal salt. The antistatic agent in the release agent layer is a Li salt, and at least one selected from the group consisting of Li (CF ₃ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, and LiCF ₃ SO _3. The antistatic surface protective film according to any one of claims 10 to 13, wherein   The film for optics by which the antistatic surface protection film in any one of Claims 1-14 is bonded together.   An optical component comprising the antistatic surface protective film according to claim 1 attached thereto.

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