CN115247034A

CN115247034A - Surface protective film and optical component

Info

Publication number: CN115247034A
Application number: CN202210396973.6A
Authority: CN
Inventors: 小林弘幸; 五十岚智美; 新见洋人; 积田幸衣; 山口和哉; 林益史
Original assignee: Fujimori Kogyo Co Ltd
Current assignee: Fujimori Kogyo Co Ltd
Priority date: 2021-04-28
Filing date: 2022-04-15
Publication date: 2022-10-28
Also published as: KR20220148096A; JP2022170032A; TW202311465A

Abstract

Provided are a surface protective film and an optical component. The surface protection film (10) is provided with: a base film (1) made of a transparent resin; an antistatic agent layer (2) formed on one surface of the base film (1); and a pressure-sensitive adhesive layer (3) formed on the surface of the base film (1) opposite to the antistatic agent layer (2). The antistatic agent layer (2) is provided with: a first layer (2 a) comprising an electrically conductive polymer; and a second layer (2 b) which is provided on the opposite side of the substrate film (1) with respect to the first layer (2 a) and which contains nanocarbon.

Description

Surface protective film and optical component

Technical Field

The present invention relates to a surface protective film and an optical component.

Background

In the production and transportation of optical films such as polarizing plates, retardation plates, lens films for displays, antireflection films, hard coat films, and transparent conductive films for touch panels, and displays and other optical products using these films, a surface protective film is bonded to the surface of the optical film to prevent stains or scratches on the surface in the subsequent steps. In order to eliminate the trouble of peeling off the surface protective film and bonding it again, and to improve the work efficiency, the visual inspection of the optical film as a product may be performed in a state where the surface protective film is bonded to the optical film.

Conventionally, in the production process of optical products, in order to prevent scratches and stains from adhering to the surface of the optical products, a surface protective film in which an adhesive layer is provided on one surface of a base film has been generally used. The surface protective film is bonded to the optical film via a micro-adhesive layer. The reason why the pressure-sensitive adhesive layer has a micro-adhesive force is that when the used surface protective film is peeled off and removed from the surface of the optical film, the surface protective film can be easily peeled off, and the pressure-sensitive adhesive is prevented from adhering to the optical film of the adherend, i.e., the product, and remaining (so-called adhesive residue is prevented from occurring).

As the surface protective film, a film in which an antistatic layer is provided on the surface of the base film opposite to the pressure-sensitive adhesive layer is frequently used. By providing an antistatic layer on the surface of the surface protective film, static electricity generated when the optical product to which the surface protective film is attached is conveyed or handled in the manufacturing process of the optical product is suppressed. This prevents dust and dust from being adsorbed in the environment, and facilitates the appearance inspection of the optical film in a state where the surface protective film is bonded thereto. In addition, when the used surface protective film is peeled and removed from a polarizing plate or a retardation plate incorporated in a liquid crystal display panel, significant peeling static electricity is suppressed, and destruction of circuits such as a driver IC is also suppressed.

As an antistatic layer on the surface of the surface protective film, a layer in which various surfactants (nonionic, cationic, anionic, amphoteric surfactants) or polymers containing ionic groups are combined, a layer in which metal or metal oxide is deposited, a layer in which particles of metal or metal oxide are combined, and the like have been proposed.

An antistatic layer combined with a surfactant, an ionic group-containing polymer, or the like is susceptible to humidity in the environment, and has a high antistatic effect in an environment with high humidity, but has a problem in that antistatic performance is remarkably deteriorated in an environment with low humidity. On the other hand, an antistatic layer to which particles of a metal or a metal oxide are added is less likely to be affected by humidity in the environment, but is less likely to exhibit transparency, and cannot be used for inspection of optical products, particularly inspection in a state where a surface protective film is attached. As the antistatic layer which is hardly affected by humidity in the environment and has transparency, there is an antistatic layer in which a metal oxide such as Indium Tin Oxide (ITO) or Antimony Tin Oxide (ATO) is deposited, but there is a problem in that the cost for deposition is very high.

Patent document 1 discloses a surface protective film in which an antistatic layer is provided on one surface of a polyester film, an antifouling layer is provided on the antistatic layer, and a micro-adhesive layer is provided on the opposite surface. The antistatic layer contains a conductive polymer obtained by polymerizing thiophene and/or a thiophene derivative. However, there is a problem that, when an antistatic layer is formed using the conductive polymer, problems such as an increase (deterioration) in surface resistivity accompanying oxidative deterioration or photo-deterioration occur with the passage of time.

In order to solve such a problem of an increase (deterioration) in surface resistivity with time, patent document 2 proposes a surface protective film in which an antistatic layer contains polyaniline sulfonic acid, polythiophene doped with a polyanion, and a binder. This surface protective film suppresses an increase (deterioration) in surface resistivity with time by using polyaniline sulfonic acid in addition to the antistatic layer, but may be colored from yellow to green by polyaniline, and is not easily used for optical components.

Patent document 3 proposes an antistatic film having good transparency (total light transmittance) and good adhesion to an antistatic layer of a base material, further having a conductive layer containing nanocarbon and a polymer, and having a surface resistivity of 1 × 10 ¹¹ Omega/\ 9633and the following antistatic film. However, since the antistatic film uses nanocarbon such as carbon nanotubes as an antistatic agent, although the surface resistance value is little increased with time, there is a problem in that the surface resistance value is increased (deteriorated) when the film is in a hot and humid environment (for example, a condition of 60 ℃ and 90% relative humidity).

Patent document 4 proposes a heat-curable antistatic coating agent containing polythiophene and a conductive filler. The thermosetting antistatic coating agent has little change in surface resistivity with time. However, there is a problem in that when the heat-curable antistatic coating agent is in a hot and humid state (conditions of 60 ℃ C., 90% relative humidity, etc.) at a high temperature, the surface resistance value is increased (deteriorated).

Patent document 1: japanese patent laid-open publication No. 2000-026817

Patent document 2: japanese Re-Table 2018-012545

Patent document 3: japanese patent laid-open publication No. 2012-166452

Patent document 4: japanese patent laid-open publication No. 2016-216714

Disclosure of Invention

In view of the above circumstances, an object of one embodiment of the present invention is to provide a surface protective film and an optical component that are less likely to cause an increase in surface resistance value.

One embodiment of the present invention provides a surface protective film, including: a base film made of a resin having transparency; an antistatic agent layer formed on one surface of the base material film; and a pressure-sensitive adhesive layer formed on a surface of the base film opposite to the antistatic agent layer, the antistatic agent layer including: a first layer comprising a conductive polymer; and a second layer which is provided on the opposite side of the base material film with respect to the first layer and contains nanocarbon.

The surface protective film may be formed by bonding a release film to the side of the pressure-sensitive adhesive layer opposite to the base film.

Preferably, the adhesive layer is composed of an acrylic adhesive.

Another embodiment of the present invention provides an optical member to which the surface protective film is bonded.

An embodiment of the present invention can provide a surface protective film and an optical component in which a surface resistance value is not easily increased.

Drawings

Fig. 1 is a sectional view showing a surface protective film of an embodiment.

Fig. 2 is a sectional view showing a surface protective film with a release film in which a release film is bonded to the surface protective film of the embodiment.

Fig. 3 is a sectional view showing one embodiment of the optical member of the present invention.

(description of reference numerals)

1: substrate film, 2: antistatic agent layer, 2a: first layer, 2b: second layer, 3: adhesive layer, 4: release film, 5: adherend (optical member), 10: surface protective film, 11: surface protective film with release film, 20: an optical component.

Detailed Description

The present invention will be described in detail below based on embodiments.

Fig. 1 is a sectional view showing a surface protective film of an embodiment. As shown in fig. 1, the surface protection film 10 according to the embodiment has an antistatic agent layer 2 formed on one surface (upper surface in fig. 1) of a base film 1. The pressure-sensitive adhesive layer 3 is formed on the surface (lower surface in fig. 1) of the base film 1 opposite to the antistatic agent layer 2.

[ base film ]

As the base film 1, a base film made of a resin having transparency and flexibility is used. Thus, the surface protective film 10 can be attached to the optical member as an adherend, and the optical member can be visually inspected. As the substrate film 1 used as the substrate film 1, a film (polyester film) formed of a polyester such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate or the like is preferably used. In addition to the polyester film, a film made of another resin may be used as long as it has a desired strength and optical compatibility. The substrate film 1 may be a non-stretched film, or may be a uniaxially or biaxially stretched film. The stretch ratio of the stretched film and the orientation angle of the axial direction method associated with the formation of crystallization of the stretched film may be controlled to specific values.

"transparent" means that, for example, when measured in a measurement wavelength range of 380nm to 780nm, the visible light transmittance calculated as the average value of the transmittances in the thickness direction in the entire wavelength region is 50% or more (preferably 70% or more, and more preferably 80% or more). The light transmittance may be measured according to JIS K7375: the "method for determining the plastic-total light transmittance and the total light reflectance" defined in 2008 is measured.

The thickness of the base film 1 is not particularly limited, but is preferably about 12 to 100 μm, and more preferably about 20 to 50 μm, because handling is easy.

If necessary, the surface of the base material film 1 may be subjected to an easy adhesion treatment such as surface modification by corona discharge or coating with a primer.

[ antistatic agent layer ]

The antistatic agent layer 2 is formed by laminating a first layer 2a containing a conductive polymer and a second layer 2b containing nanocarbon in this order from the substrate film 1 side. The second layer 2b is provided on the opposite side (upper side in fig. 1) of the base film 1 from the first layer 2a.

The layer containing a conductive polymer may have an increase (deterioration) in surface resistivity with oxidation deterioration or photo-deterioration with the lapse of time, but in the surface protective film 10, the second layer 2b containing nanocarbon is provided on the surface of the first layer 2a (the surface opposite to the base film 1), thereby overcoming the technical problem of oxidation deterioration or photo-deterioration of the first layer 2a containing a conductive polymer.

When the layer containing nanocarbon is in a moist heat environment (e.g., 60 ℃, a condition of 90% relative humidity, etc.), the surface resistance value may be raised (deteriorated), but, in the surface protection film 10, the technical problem of deterioration of the second layer 2b in a moist heat environment is also overcome by the antistatic effect of the first layer 2a existing between the second layer 2b and the substrate film 1.

Examples of the conductive polymer used for the first layer 2a include: polyaniline, polythiophene, polypyrrole, and derivatives thereof.

As polyaniline and its derivatives, there can be obtained: polyaniline (manufactured by ALDRICH Co., ltd.), polyaniline (emeraldine salt) (manufactured by ALDRICH Co., ltd.), OMEGACON (registered trademark) D1033W, OMEGACON (registered trademark) NW-D102MT, OMEGACON (registered trademark) NW-F102ET, OMEGACON (registered trademark) NW-F101MEK (manufactured by Nissan chemical industries, ltd.), \1245012463971X (manufactured by Mitsubishi chemical Co., ltd.), a toluene solution PANT (manufactured by chemical industries, ltd.), and the like.

Commercially available products of polythiophene and its derivatives can be obtained: 3,4-ethylenedioxythiophene (3, 4-ethylenedioxythiophene) (BAYTRON (registered trademark) MV 2), 3,4-polyethylenedioxythiophene/polystyrene sulfonate (3, 4-polyethylenedioxythiophene/polystyrene sulfonate) (BAYTRON (registered trademark) P, BAYTRON (registered trademark) C), BAYTRON (registered trademark) FE, BAYTRON (registered trademark) MV2, BAYTRON (registered trademark) P, BAYTRON (registered trademark) PAG, BAYTRON (registered trademark) PHC 4, BAYTRON (registered trademark) PH500, BAYTRON (registered trademark) PH510 (or more, EGK (manufactured by EGPRON), SEYDA (registered trademark) AS-Q, SEYD A (registered trademark) PH500, conductive coat S800 (manufactured by SEYTRON-200 or more), conductive coat S800 (manufactured by SEYTRON-1000), conductive coat S800 or more), conductive coat S-800 (conductive coat S-800, and so on conductive coat S-200).

As polypyrrole and its derivatives, there can be obtained: polypyrrole (ALDRICH corporation), SSPY (chemical industry corporation), and the like.

The conductive polymer is preferably polythiophene in view of antistatic property and coloring property (color tone). The polythiophene is preferably polyethyleneoxythiophene (polyethyleneoxythiophene), and particularly preferably Polyethylenedioxythiophene (PEDOT). The polyethylenedioxythiophene is preferably doped polystyrenesulfonic acid (PSS) as dopant (dopant). The PSS-doped polyethylene dioxythiophene has the property of being easily dissolved in water, and has the advantages of excellent heat resistance, moisture resistance and UV stability.

The conductive polymer may be used alone or in combination of two or more. In addition, in order to improve the coatability of the antistatic agent to the base film 1, the adhesiveness of the antistatic agent layer to the base film, the film strength of the antistatic agent layer, and the durability (abrasion resistance, solvent resistance, and the like) of the film, a binder resin, a crosslinking agent, an ultraviolet absorber, an antioxidant, a leveling agent (a wettability improving agent), an adhesiveness improving agent, and the like may be added to the electroconductive polymer.

In order to form the first layer 2a, it is preferable to form a film of a conductive polymer to which a binder resin is added, rather than a film of a conductive polymer alone. Examples of the binder resin include: acrylic resins, epoxy resins, urethane resins, phenolic resins, polyester resins, and the like. In order to crosslink (also referred to as cure) these resins, a crosslinking agent may be added to the binder resin as necessary. Examples of the crosslinking agent include: isocyanate compounds, melamine compounds, epoxy compounds, metal chelate compounds, and the like.

The method for forming the first layer 2a on the substrate film 1 may be a known method. For example, a coating material containing an antistatic agent (a coating material containing an antistatic agent and a binder resin) is applied to the base film 1 by a known coating method. The formed coating is cured by heating or ultraviolet irradiation, whereby the first layer 2a can be formed. Examples of the coating method include reverse coating, comma blade coating, gravure coating, slit coating, mayer rod coating, and air knife coating.

Examples of the nanocarbon used for the second layer 2b include: carbon Nanotubes (CNTs), graphene, fullerenes, and the like. Carbon nanotubes include single-layer CNTs and multi-layer CNTs. The antistatic function of single-layer CNTs, multi-layer CNTs, graphene, and fullerenes is excellent, but the single-layer CNTs, graphene, and fullerenes are expensive, and therefore the multi-layer CNTs are easy to use. In order to prevent the first layer 2a from being exposed to the air, the second layer 2b is formed on the surface of the first layer 2a. Thus, the first layer 2a is not directly exposed to the air, and therefore the first layer 2a is less susceptible to oxidative deterioration.

Since nanocarbon alone cannot exhibit film strength, it is preferably used as a coating material by adding a binder resin, a dispersant, or the like. In addition, in order to improve the coating property of the antistatic agent, the adhesiveness of the antistatic agent layer (adhesiveness to the first layer 2 a), the film strength of the antistatic agent layer, and the durability of the film (abrasion resistance, solvent resistance, and the like), a crosslinking agent, an ultraviolet absorber, an antioxidant, a leveling agent (wettability improver), an adhesiveness improver, and the like may be added to the nanocarbon.

One kind of nanocarbon may be used, or a plurality of kinds of nanocarbon may be used in combination. Examples of the binder resin include: acrylic resins, epoxy resins, urethane resins, phenolic resins, polyester resins, and the like. In order to crosslink (also referred to as cure) these resins, a crosslinking agent may be added to the binder resin as needed. Examples of the crosslinking agent include: isocyanate compounds, melamine compounds, epoxy compounds, metal chelate compounds, and the like.

For forming the second layer 2b, a commercially available coating material can be used as a coating material for the antistatic agent. Examples of commercially available products include: dentron C-300, dentron CD-001 (manufactured by NAGASE CHEMTEX Co., ltd.), COLCOAT CS-3002, COLCOAT CS-3202 (manufactured by COLCOAT Co., ltd.), and the like.

The method of forming the second layer 2b on the surface of the first layer 2a may be a known method. For example, a coating material containing nanocarbon (coating material containing nanocarbon and binder resin) is applied to the surface of the first layer 2a by using a known coating method. The formed coating is cured by heating or ultraviolet irradiation, whereby the second layer 2b can be formed. Examples of the coating method include reverse coating, comma blade coating, gravure coating, slit coating, mayer rod coating, and air knife coating.

The thicknesses of the first layer 2a and the second layer 2b are not particularly limited. The thickness of the first layer 2a is determined by the amounts of the conductive polymer and the binder resin. The thickness of the second layer 2b is determined by the amounts of nanocarbon and binder resin. The thicknesses of the first layer 2a and the second layer 2b can be adjusted to 7 th power (10) of 10 in the state where the first layer 2a and the second layer 2b are laminated such that the surface resistivity becomes 10 ⁷ ) 9 th power of 10 (10) ⁹ ) Left and right.

[ adhesive layer ]

The pressure-sensitive adhesive layer 3 preferably has properties of adhering to the surface of an adherend, being easily peeled off after use, and being less likely to contaminate the adherend. Examples of the adhesive used for the adhesive layer 3 include: and adhesives such as acrylic adhesives, urethane adhesives, and rubber adhesives. As the binder, an adhesive resin such as a polyethylene vinyl acetate resin may be used. Among these, acrylic adhesives and urethane adhesives are particularly preferable.

As the acrylic pressure-sensitive adhesive, a pressure-sensitive adhesive obtained by adding a crosslinking agent to a (meth) acrylic polymer (acrylic resin composition) is preferable. The (meth) acrylic polymer is preferably: the main monomers of n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate and the like; comonomers such as acrylonitrile, vinyl acetate, methyl methacrylate, and ethyl acrylate; and polymers obtained by copolymerizing functional monomers such as acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, and N-methylolmethacrylamide. The monomer composition constituting the (meth) acrylic polymer is preferably 50% or more of the (meth) acrylic monomer, and may be 100% of the (meth) acrylic monomer.

The crosslinking agent crosslinks the (meth) acrylic polymer. Examples of the crosslinking agent include: isocyanate compounds, epoxy compounds, melamine compounds, metal chelate compounds, and the like. The amount of the crosslinking agent to be added may be determined in consideration of the kind, polymerization degree, functional group amount, and the like of the (meth) acrylic polymer. The amount of the crosslinking agent to be added is not particularly limited, but is preferably about 0.5 to 1.0 part by mass per 100 parts by mass of the (meth) acrylic polymer.

The urethane adhesive is preferably a polyurethane resin containing a polyol component and a polyisocyanate component. The polyurethane resin may be selected in consideration of adhesiveness, wettability, staining of an adherend, and the like. The polyol component and the polyisocyanate component are not particularly limited. The polyurethane resin may be used alone or in combination of two or more.

Examples of the polyol component include: polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, castor oil polyols, and the like. These polyol components may be used alone or in combination of two or more.

As the polyisocyanate component, aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, polymer of diisocyanate, or the like is used. These polyisocyanate components may be used alone or in combination of two or more.

Commercially available products of polyurethane-based adhesives include: \12469. The adhesive layer may be formed by crosslinking or curing a polyurethane adhesive.

In order to promote the crosslinking reaction, a crosslinking catalyst may be added as an additive to the adhesive layer 3 as necessary. In order to improve the adhesion between the base film 1 and the pressure-sensitive adhesive, an adhesion improving agent such as a silane coupling agent may be added as an additive to the pressure-sensitive adhesive layer 3 as necessary. Additives such as antistatic agents, antioxidants, and ultraviolet absorbers may be added to the pressure-sensitive adhesive layer 3 as needed.

The thickness of the pressure-sensitive adhesive layer 3 is not particularly limited, and is, for example, preferably about 5 μm to 40 μm, and more preferably about 10 μm to 30 μm. The adhesive strength (low-speed adhesive strength) of the surface of the adherend to the surface protective film at a peeling speed of 0.3 m/min is preferably 0.3N/25mm or less, and more preferably 0.2N/25mm or less. The adhesive strength (high-speed adhesive strength) at a peeling speed of 30 m/min is preferably 0.8N/25mm or less. If the high-speed adhesive strength is more than 0.8N/25mm, workability in peeling off the post-use protective film may be deteriorated. For the adjustment of the adhesive force, known methods such as a change in the composition of the adhesive, an adjustment of the addition amount of a curing agent, and an adjustment of the addition amount of a tackifier or an adhesive force adjuster can be used. By these methods, the adhesive force of the adhesive layer 3 may be matched to a predetermined adhesive force.

As a method for forming the pressure-sensitive adhesive layer 3 on the surface of the base film 1, a known method can be used. Specifically, a known coating method such as reverse coating, comma blade coating, gravure coating, slot coating, mayer rod coating, or air knife coating can be used.

Fig. 2 is a sectional view showing a surface protection film with a release film 11 in which the release film 4 is bonded to the surface protection film 10. As shown in fig. 2, a known release film may be used as the release film 4. As the release film 4, a polyolefin film such as a polyethylene film or a polypropylene film, a fluorine film, or the like can be used as a film material. The release film 4 may be a release film in which a resin film is treated with a release agent (also referred to as a release agent). Examples of the resin film include: polyester films such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), and polyamide films. Examples of the release agent include: silicone resins, resins containing long-chain alkyl groups, fluorine resins, and the like. Among them, a release film obtained by treating a PET film with a silicon-based release agent is preferable.

The thickness of the release film is not particularly limited, and a release film having a thickness of 12 μm to 38 μm is frequently used in view of workability and cost.

The method of forming the pressure-sensitive adhesive layer 3 on the base film 1 and the method of bonding the release film 4 to the pressure-sensitive adhesive layer 3 can be carried out by known methods and are not particularly limited. Specifically, there may be mentioned: (1) A method of applying and drying a resin composition for forming the pressure-sensitive adhesive layer 3 on one surface of the base film 1 to form the pressure-sensitive adhesive layer 3, and then bonding the pressure-sensitive adhesive layer 3 to the pressure-sensitive adhesive layer 3, and a method of (2) applying and drying a resin composition for forming the pressure-sensitive adhesive layer 3 on the surface of the release film 4 to form the pressure-sensitive adhesive layer 3, and then bonding the base film 1 to the pressure-sensitive adhesive layer 3, and the like.

Fig. 3 is a sectional view showing an embodiment of the optical member of the present invention. Fig. 3 shows the optical member 20 to which the surface protective film 10 is attached. As shown in fig. 3, the surface protection film with release film 11 (see fig. 2) is in a state where the release film 4 is peeled off and the pressure-sensitive adhesive layer 3 is exposed. The surface protective film (see fig. 1) is bonded to an optical member 5 as an adherend via an adhesive layer 3.

Examples of the optical member include: optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate which also serves as a retardation plate, and a polarizing plate which also serves as a lens film. Such optical members are used as components of liquid crystal display devices such as liquid crystal display panels, and optical devices such as various meters. Further, as the optical member, there can be mentioned: optical films such as antireflection films, hard coat films, and transparent conductive films for touch panels.

According to the optical member of the embodiment, in a state where the surface protective film is bonded to the optical member (optical film) as an adherend, the antistatic agent layer is present on the surface of the surface protective film. Thus, static electricity generated when the optical component is conveyed or handled can be suppressed to be low. Therefore, adsorption of substances that cause foreign matter such as dust and dust in the process can be suppressed, and an optical component with few defects can be obtained. Further, when the surface protective film is peeled off and removed from the optical member, peeling static electricity can be suppressed to be low, and thus, there is little possibility that circuit components such as a driver IC, a TFT element, a gate line driver circuit, and the like are damaged. Therefore, for example, it is possible to improve the production efficiency in the process of manufacturing a liquid crystal display panel or the like and to maintain the reliability of the production process.

The surface protective film of the embodiment can suppress an increase (deterioration) in the surface resistance value of the antistatic agent layer on the surface even when exposed to an external gas or a moist heat environment, and therefore the above effects are less likely to change over time, and the industrial value is high.

[ examples ]

The present invention will be further illustrated by examples.

(example 1)

As an antistatic agent composition containing a conductive polymer, an antistatic agent a containing a polythiophene type antistatic agent (BAYTRON (registered trademark) PAG manufactured by STARK corporation), an acrylic resin (SWX-079R manufactured by kokusoh oil and fat corporation) \\\ 1250612473125247231 (pessresin; registered trademark) and a methylated melamine crosslinking agent (124911241245912521246363 (nicaak; registered trademark).

As an antistatic agent composition containing nanocarbon, an antistatic agent B containing a carbon nanotube dispersion (1248790124881252512531 (DENATRON; registered trademark) CD-100, manufactured by NAGASE CHEMTEX, a blend of (12506124731257212531 (PERSESIN; registered trademark) SWX-079R) and a methylated melamine crosslinking agent (12491124591242112412412412463manufactured by JASCENE INDUSTRIAL.

An adhesive comprising a copolymer of 80 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of butyl acrylate, 7 parts by mass of methoxypolyethylene glycol (400) methacrylate, and 3 parts by mass of 2-hydroxyethyl acrylate was formulated. The adhesive is an acrylic adhesive. 0.3 part by mass of lithium bis (trifluoromethanesulfonyl) imide as an antistatic agent and 2 parts by mass of "TOSOH corporation \\12425124931251254088 (CORONATE; registered trademark) HX" (manufactured by TOSOH corporation) as an isocyanate curing agent were added to 100 parts by mass of the 40% ethyl acetate solution of the adhesive, and mixed with stirring to obtain an adhesive composition 1.

The antistatic agent a was diluted 10 times with water/ethanol (water/ethanol mass ratio 50/50) to obtain a first dope. The first coating material was applied to the surface of a polyethylene terephthalate film (PET film, base film) having a thickness of 38 μm so that the thickness after drying became 0.15 μm, and dried in a hot air circulating oven at 120 ℃ for 1 minute. Thereby, the first layer is formed.

The antistatic agent B was diluted 10 times with water/ethanol (water/ethanol mass ratio 50/50) to obtain a second dope. The second coating material was applied to the surface of the first layer so that the thickness after drying became 0.05 μm, and dried in a hot air circulation type oven at 120 ℃ for 1 minute. Thereby, the second layer is formed.

Through the above steps, an antistatic film in which the base film (PET film)/the first layer (antistatic agent a)/the second layer (antistatic agent B) were laminated in this order was obtained.

On the surface of the PET film on which the antistatic agent layer was not laminated, the adhesive composition 1 was applied with an applicator so that the thickness after drying became 20 μm, and dried in a hot air circulation oven at 120 ℃ for 3 minutes. Thereby, an adhesive layer is formed.

A release film (25 μm thick) treated with a silicon-based release agent was applied to the surface of the adhesive layer (a film having a thickness of (v) \124801245212512516. The obtained surface protective film with a release film was aged at 40 ℃ for 3 days to obtain a surface protective film of example 1.

(example 2)

A surface protective film of example 2 was produced in the same manner as in example 1, except that the thickness of the first layer and the thickness of the second layer were each set to 0.1 μm.

(example 3)

A surface protective film of example 3 was produced in the same manner as in example 1, except that the thickness of the first layer was set to 0.05 μm and the thickness of the second layer was set to 0.15 μm.

(example 4)

A surface protective film of example 4 was produced in the same manner as in example 2, except for the adhesive and the curing agent.

As the adhesive, a urethane adhesive (v manufactured by mitaka chemical industries, inc. \\ 124501\\ 124674012588; registered trademark) FT 200) instead of the acrylic adhesive. As the curing agent, 5.7 parts by mass of "CL 2503 (content of non-volatile components of curing agent: 40% by mass)" was used in place of 2 parts by mass of "1246712525125938820 manufactured by TOSOH Corona chemical industries, inc..

(example 5)

The surface protective film of example 5 was produced in the same manner as in example 2 except that polyester resin (Toyo spinned \\12496124521252590125125125231250 (VYLONAL; registered trademark) MD-1480) was used in place of acrylic resin (\1250612473125125241247212512512531 (PESRESIN; registered trademark) SWX-079R.

Comparative example 1

A surface protective film of comparative example 1 was obtained in the same manner as in example 1, except that the thickness of the first layer was set to 0.2 μm and the second layer was not present.

Comparative example 2

A surface protective film of comparative example 2 was obtained in the same manner as in example 1, except that the first layer was not provided and the thickness of the second layer was set to 0.2 μm.

Comparative example 3

A surface protective film of comparative example 3 was produced in the same manner as in example 2, except that the antistatic agent layer having a single-layer structure was used instead of the antistatic agent layer having a two-layer structure.

The antistatic agent layer having a single-layer structure is formed by applying an antistatic agent in which an antistatic agent a and an antistatic agent B are mixed so that the solid content mass ratio becomes 50/50, so that the thickness after drying becomes 0.2 μm.

Comparative example 4

A surface protective film of comparative example 4 was obtained in the same manner as in example 2, except that the positions of the first layer and the second layer were reversed.

Comparative example 5

A surface protective film of comparative example 5 was produced in the same manner as in example 1, except that the first layer and the second layer were not provided.

The method and results of the evaluation test are shown below.

(method of measuring surface intrinsic resistance value of surface protective film)

The surface resistivity of the surface protective film was measured using a high-performance high resistivity meter (V124951252412524796 (HIRESTA; registered trademark) -UP) under the conditions of an applied voltage of 100V and a measurement time of 30 seconds (Ω/\9633.

(method of evaluating moist Heat resistance)

The surface protective film was left at 60 ℃ and 90% relative humidity for a predetermined period of time (1 day or 30 days), and then left at 23 ℃ and 50% relative humidity for 1 hour. The surface resistivity of the surface protective film was measured using a high-performance high resistivity meter (V124951252412524796 (HIRESTA; registered trademark) -UP) under the conditions of an applied voltage of 100V and a measurement time of 30 seconds (Ω/\9633.

(method of evaluating Exposure resistance)

The surface protective film was left to stand in a state where the surface was exposed to air at a temperature of 23 ℃ and a relative humidity of 50% for a predetermined time (1 day or 30 days). The surface resistivity of the surface protective film was measured using a high-performance high resistivity meter (V12495v (1245212524792, manufactured by Mitsubishi chemical analysis technologies, inc.).

Method for measuring low-speed adhesive force of surface protective film

And adhering the TAC film to the surface of the glass plate by using an adhering machine. Then, the surface protective film cut to a width of 25mm was attached to the surface of the polarizing plate, and then stored for 1 day in a test environment of 23 ℃. Times.50% RH. Then, the strength when the surface protective film was peeled in a 180 ° direction at a peeling speed of 0.3 m/min was measured using a tensile tester, and this was regarded as a low-speed adhesive force (N/25 mm).

Method for measuring high-speed adhesive force of surface protective film

And adhering the TAC film to the surface of the glass plate by using an adhering machine. Then, the surface protective film cut to a width of 25mm was attached to the surface of the polarizing plate, and then stored for 1 day in a test environment of 23 ℃x50% rh. Then, the strength of the surface protective film when peeled at a peeling rate of 30m per minute was measured by using a high speed peeling TESTER (manufactured by TESTER INDUSTRIAL Co., ltd.) and was defined as a high speed adhesive strength (N/25 mm).

Method for measuring electrostatic voltage for peeling surface protective film

And adhering the TAC film to the surface of the glass plate by using an adhering machine. Then, the surface protective film cut to a width of 25mm was attached to the surface of the polarizing plate, and then stored for 1 day in a test environment of 23 ℃. Times.50% RH. Then, the maximum value of the absolute value of the surface potential when the surface protective film was peeled at a peeling rate of 30m per minute using a high speed peeling TESTER (manufactured by TESTER industries), and the surface potential of the surface of the polarizing plate was measured every 10ms using a surface potentiometer (manufactured by KEYENCE corporation) was set as the peeling electrostatic voltage (kV).

Method for confirming surface contamination of surface protective film

And adhering the TAC film to the surface of the glass plate by using an adhering machine. Then, the surface protective film cut to a width of 25mm was attached to the surface of the polarizing plate, and then stored for 3 days in a test environment of 23 ℃x50% rh. After that, the surface protective film was peeled off, and the staining property of the surface of the polarizing plate was visually observed. As a criterion for judging the surface contamination property, a case where no contamination migration was observed in the polarizing plate was judged as "o" (good), and a case where contamination migration was observed in the polarizing plate was judged as "x" (bad).

The measurement results of the surface protective films of examples 1 to 5 and comparative examples 1 to 5 are shown in tables 1 to 3. In tables 1 to 3, "CNT" represents a ratio of the thickness of the second layer to the total thickness of the first layer and the second layer. "PEDOT" denotes the ratio of the thickness of the first layer relative to the total thickness of the first and second layers. "CNT/PEDOT (Mix)" represents a mixing ratio of the antistatic agent B and the antistatic agent a in the antistatic agent (mixture) when the antistatic agent layer having a single-layer structure is used. "100 (50/50)" means that the solid content mass ratio of the antistatic agent A and the antistatic agent B are both 50%.

"antistatic agent layer lamination order" means the lamination order of the first layer and the second layer. "o" indicates that the order of lamination of the substrate film, the first layer, and the second layer is "substrate film/second layer/first layer".

The "∘" in the "acrylic resin" means that the binder resin of the first layer and of the second layer is an acrylic resin. The "∘" in "polyester resin" means that the binder resin of the first layer and the second layer is a polyester resin.

The ". Smallcircle" in "acrylic adhesive" indicates that an acrylic adhesive was used as the adhesive. The ". Smallcircle" in "urethane adhesive" indicates that a urethane-based adhesive is used as the adhesive. 1.0E +09 of the surface intrinsic resistance value represents a power of 9 of 1.0X 10. 1.0E +13< represents exceeding the measurement limit (13 th power of 1.0X 10) of the measurement device (high-performance high-resistivity meter) to become an overrange.

TABLE 1

	Example 1	Example 2	Example 3	Example 4
					CNT(％)	25	50	75	50
PEDOT(％)	75	50	25	50
					CNT/PEDOT(Mix)
Antistatic agent layer lamination forward and backward
					Acrylic resin	○	○	○	○
Polyester resin
					Acrylic adhesive	○	○	○
Urethane adhesive				○
					Surface intrinsic resistance value (omega/\9633;)	1.0E+09	9.4E+08	8.2E+08	9.2E+08
Wet heat resistance for 1 day	8.7E+08	9.1E+08	8.8E+08	9.2E+08
					30 days	9.8E+08	9.6E+08	1.0E+09	9.7E+08
Resistance to Exposure for 1 day	1.1E+09	9.5E+08	8.3E+08	9.3E+08
					30 days	1.3E+09	9.3E+08	8.6E+08	9.3E+08
Low adhesion (N/25 mm)	0.04	0.04	0.04	0.02
					High speed adhesion (N/25 m)	0.62	0.60	0.62	0.43
Peel off static voltage (kV)	0.3	0.3	0.2	0.3
					Surface contamination for 3 days	○	○	○	○

TABLE 2

	Example 5	Comparative example 1	Comparative example 2	Comparative example 3
					CNT(％)	50		100
PEDOT(％)	50	100
					CNT/PEDOT(Mix)				100(50/50)
Antistatic agent layer lamination forward and backward
					Acrylic resin		○	○	○
Polyester resin	○
					Acrylic adhesive	○	○	○	○
Urethane adhesive
					Surface intrinsic resistance value (omega/\ 9633;)	8.4E+08	9.0E+08	7.5E+08	8.3E+08
Wet heat resistance for 1 day	8.3E+08	5.3E+08	8.9E+08	8.8E+08
					30 days	9.1E+08	5.1E+10	6.8E+10	4.2E+09
Resistance to Exposure for 1 day	8.4E+08	1.1E+09	7.7E+09	8.6E+08
					30 days	9.5E+08	7.7E+11	8.9E+11	3.7E+10
Low adhesion (N/25 mm)	0.04	0.04	0.03	0.04
					High adhesion (N/25 mm)	0.61	0.64	0.60	0.61
Peel off static voltage (kV)	0.3	0.3	0.3	0.3
					Surface contamination for 3 days	○	○	○	○

TABLE 3

	Comparative example 4	Comparative example 5
			CNT(％)	50
PEDOT(％)	50
			CNT/PEDOT(Mix)
Lamination of antistatic agent layers	○
			Acrylic resin	○	○
Polyester resin
			Acrylic adhesive	○	○
Urethane adhesive
			Surface intrinsic resistance value (omega/\9633;)	9.1E+08	1.0E+13<
Moisture and heat resistance for 1 day	8.7E+08	1.0E+13<
			30 days	9.8E+09	1.0E+13<
Resistance to Exposure for 1 day	1.03E+09	1.0E+13<
			30 days	4.4E+10	1.0E+13<
Low adhesion (N/25 mm)	0.04	0.04
			High adhesion (N/25 mm)	0.61	0.68
Peel off static voltage (kV)	0.3	0.9
			Surface contamination for 3 days	○	○

The following results were obtained from the measurement results shown in tables 1 to 3.

The surface protective films of examples 1 to 5 did not increase (deteriorate) the surface resistance value of the antistatic agent layer even when exposed to the external air and the moist heat environment.

On the other hand, in comparative example 1 in which the antistatic agent layer was formed only of the first layer (containing a conductive polymer), it was observed that the surface resistance value of the antistatic agent layer was increased (deteriorated) when exposed to the external gas.

In comparative example 2 in which the antistatic agent layer was formed of only the second layer (containing nanocarbon), it was observed that the surface resistance value of the antistatic agent layer on the surface was increased (deteriorated) under a moist heat environment.

In comparative example 3 in which the antistatic agent layer was not a two-layer structure but a single-layer structure composed of a mixture of the antistatic agents a, B, the surface resistance value of the antistatic agent layer slightly increased (deteriorated) under a moist heat environment. In an environment exposed to external gas, the surface resistance value of the antistatic agent layer on the surface is greatly increased (deteriorated).

In comparative example 4 in which the order of laminating the antistatic agent layers is reversed from examples 1 to 5, it was observed that the surface resistance value of the antistatic agent layer on the surface was increased (deteriorated) under the environment exposed to the external air and the moist heat environment.

In comparative example 5 in which no antistatic agent layer was provided, it is estimated that static electricity is likely to be generated in the process because the surface resistance value of the surface protective film is high.

The surface protective film according to the embodiment can be used for protecting the surface by being bonded to an optical film such as a polarizing plate, a retardation plate, or a lens film, or other various optical members in a production process thereof. The surface protective film of the embodiment can suppress an increase (deterioration) in the surface resistance value of the antistatic agent layer on the surface even when exposed to an external gas or a moist heat environment. The surface protective film according to the embodiment can suppress static electricity generated when an optical product to which the surface protective film is attached is conveyed or handled in a manufacturing process of the optical product, thereby reducing adsorption of dust or dust in the environment. The surface protective film according to the embodiment can suppress significant peeling static electricity when the used surface protective film is peeled and removed from a polarizing plate or a retardation plate incorporated in a liquid crystal display panel, and thus has a low possibility of damaging a circuit such as a driver IC. Therefore, the yield of the production process can be improved, and the industrial utility value is high.

Claims

1. A surface protective film is provided with:

a base film made of a transparent resin;

an antistatic agent layer formed on one surface of the base material film; and

an adhesive layer formed on the surface of the base film opposite to the antistatic agent layer,

the antistatic agent layer is provided with:

a first layer comprising a conductive polymer; and

a second layer disposed opposite to the base material film with respect to the first layer, and including nanocarbon.

2. The surface protective film according to claim 1,

a release film is bonded to the side of the pressure-sensitive adhesive layer opposite to the base film.

3. The surface protective film according to claim 1 or 2,

the adhesive layer is composed of an acrylic adhesive.

4. An optical member to which the surface protective film according to any one of claims 1 to 3 is attached.