JP2005036205A - Surface protective film, transparent conductive film, and display device - Google Patents

Abstract

[PROBLEMS] To prevent a hard coat-treated surface from being deteriorated even if a protective film attached to a hard-coated surface or the like is peeled off, and to contaminate the hard-coated treated surface after peeling in appearance. In addition, a surface protective film satisfying adhesive strength, and a transparent conductive film and a display device using the surface protective film are provided.
A surface protective film 1 for protecting a surface of a transparent conductive film 2 opposite to a conductive thin film 2b, wherein a pressure-sensitive adhesive layer 1b is provided on one side of a base film 1a. A surface protective film, wherein the pressure-sensitive adhesive layer 1b contains silicone oil.
[Selection] Figure 1

Description

  The present invention relates to a transparent conductive film or a surface protective film used for a display device widely used in the fields of liquid crystal displays, touch panels, sensors, transparent electrodes in solar cells, and the like, and a transparent conductive film using the same The present invention relates to a display device.

In general, as shown in FIG. 3, the transparent conductive film has a conductive thin film 2b made of ITO, ZnO, SnO ₂ or the like on one side of a base film 2a made of polyester or the like and a hard coat layer 2c (or on the other side). An anti-glare layer). In such a transparent conductive film 2, a surface protective film has been conventionally used in the hard coat layer 2c or anti-glare layer on the opposite side of the conductive thin film 2b in order to prevent adhesion of foreign matters and dirt. As the surface protective film, for example, a two-layer tape made of polyethylene / ethylene-vinyl acetate copolymer (PE / EVA) by a coextrusion method is used.

  For example, for the purpose of reducing man-hours and reducing costs while maintaining high quality, a transparent conductive film is formed on one side of a transparent film made of plastic, and an adhesive is applied to the side opposite to the transparent conductive film. In the transparent conductive film in which the protective film is laminated, the pressure-sensitive adhesive is transparent, the adhesive strength to the transparent film is 8.0 N / 50 mm or more, and the adhesive strength to the protective film is 0.1 N / 50 mm to 1.5 N A transparent conductive film with a protective film having a thickness of 50 mm or less is disclosed (Patent Document 1).

  In order to provide a heat-resistant transparent conductive film that can be continuously processed by a roll process that is not damaged by heat and does not damage the surface opposite to the surface on which the transparent conductive thin film is formed. A thin film having transparent conductivity is laminated on a first plastic film substrate having a temperature of 120 ° C. or higher, and a glass transition temperature is 120 ° C. or higher on the opposite side of the surface on which the thin film is laminated. An adhesive layer having a thermal decomposition temperature of 120 ° C. or higher and an adhesive strength of 50 g / cm or lower is provided on a second plastic film substrate having a difference in linear expansion coefficient from that of one plastic film of 20 ppm / ° C. or less. A transparent conductive film obtained by pasting a protective film through an adhesive layer is disclosed (Patent Document 2).

  Furthermore, for the purpose of reducing the warpage in the heating process, reducing the curl due to the heat treatment process, and improving the dimensional stability after the heat treatment, the protective film has a thermal shrinkage ratio of MD and TD after heating at 150 ° C. for 30 minutes. A first film whose direction is 0.5% or less and a second film having a coefficient of linear expansion of 40 ppm / ° C. or less, which is a difference between the coefficient of linear expansion of the transparent conductive film and the plastic film with a protective film; A transparent conductive film provided with the first film and the second film in this order from a plastic film and a plastic film with a protective film are disclosed (Patent Document 3).

However, when the protective film as described above is attached to the hard coat (or anti-glare) treated surface of the transparent conductive film and peeled off, the slipperiness of the hard coat treated surface is deteriorated. And the deterioration of slipperiness will adversely affect the writing condition with a touch pen or the like.
JP 2001-332132 A Japanese Patent Laid-Open No. 7-68690 JP-A-11-268168

  The present invention does not deteriorate the slidability of the hard-coated surface even if the protective film attached to the hard-coated surface is peeled off. It aims at providing the surface protection film which can also satisfy adhesive force without doing. Another object of the present invention is to provide a transparent conductive film and a display device using the same.

  As a result of intensive research to achieve the above object, the present inventors have found that the following problems can be solved by providing the following pressure-sensitive adhesive layer as the pressure-sensitive adhesive layer of the surface protective film, and the present invention has been completed. .

  That is, the surface protective film of the present invention is a surface protective film that protects the surface of the display unit of the display device, and a pressure-sensitive adhesive layer is provided on one side of the base film, and the pressure-sensitive adhesive layer is a silicone oil. It is characterized by containing.

  The surface protective film of the present invention is a film that protects the surface of the transparent conductive film opposite to the conductive thin film, and is provided with a pressure-sensitive adhesive layer on one side of the substrate film. The agent layer contains silicone oil.

  The surface protective film of the present invention contains silicone oil in the pressure-sensitive adhesive layer, and can transfer the silicone component to the surface of the hard coat layer (or anti-glare layer) when pasted on the transparent conductive film. . Therefore, even if the surface protective film is peeled off, the slipperiness of the hard coat treated surface is not deteriorated. Furthermore, the hard coat treated surface after peeling is not contaminated in appearance and the adhesive strength can be satisfied.

  In the present invention, the silicone oil is preferably a carbinol-modified silicone oil in which a part of the methyl group of dimethylpolysiloxane is substituted with a hydroxyalkyl group having 1 to 5 carbon atoms. By carbinol modification, it is possible to improve the releasability and further reduce the contamination of the hard coat layer surface.

Alternatively, the silicone oil is preferably a fluorine-modified silicone oil in which a part of methyl groups of dimethylpolysiloxane is substituted with —CH ₂ CH ₂ CF ₃ groups. By modifying with fluorine, it is possible to improve the releasability and further reduce the contamination of the hard coat layer surface.

  The pressure-sensitive adhesive layer preferably contains a (meth) acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive as a main component. The (meth) acrylic pressure-sensitive adhesive can easily control the adhesive force by adjusting the composition of the raw material, and the rubber-based pressure-sensitive adhesive has low adherend selectivity and can be attached to various adherends. .

  Moreover, it is preferable that the said adhesive layer contains the crosslinked body which consists of a (meth) acrylic-type polymer and a crosslinking agent. As the crosslinking agent, it is preferable to use an epoxy-based crosslinking agent. Use of an epoxy-based crosslinking agent is advantageous for light release at the time of peeling.

  The transparent conductive film of the present invention comprises a conductive thin film on one side of the base film and a hard coat layer or an antiglare layer on the other side, and the adhesive layer of the surface protective film is replaced with the hard coat layer or It is affixed to the surface of the antiglare layer.

  In addition, another transparent conductive film of the present invention includes a conductive thin film on one side of the base film, and the adhesive layer of the surface protective film is attached to the surface on the other side of the base film. It is made.

  On the other hand, the display device of the present invention includes a hard coat layer or an antiglare layer on the surface of the display unit of the display device, and the adhesive layer of the surface protective film according to any one of the above, the hard coat layer or the antiglare layer. Attached to the surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the usage state of the surface protective film of the present invention, and FIG. 2 is a cross-sectional view showing another example of the usage state.

  As shown in FIG. 1, the surface protective film of the present invention is provided with a pressure-sensitive adhesive layer 1b on one side of a base film 1a. The surface protective film of this invention protects the surface on the opposite side to the electroconductive thin film of a transparent conductive film. The embodiment shown in FIG. 1 is an example in which the surface protective film 1 is attached to the surface of the hard coat layer 2c (or the antiglare layer) of the transparent conductive film 2, and the embodiment shown in FIG. This is an example in which the surface protective film 1 is attached to the surface of the base film 2a of the film 2.

  The substrate film 1a is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polycarbonate, polymethyl methacrylate, polystyrene, polyvinyl chloride, polyethylene, Examples include polypropylene, polyethylene / polypropylene blends, polyamide, polyimide, cellulose acetate, polysulfone, and polyethersulfone. Among these, when transparency and heat resistance are required, PET, PEN, and PPS are preferable.

  Although the thickness in particular of the base film 1a is not restrict | limited, It is good to set it as 10-200 micrometers, Preferably it is 15-100 micrometers, More preferably, it is 20-70 micrometers. If the thickness is too thin, the strength when peeling the surface protective film 1 and the surface protective function tend to be insufficient. If the thickness is too thick, it tends to be disadvantageous in terms of handleability and cost. In consideration of anchoring property with the pressure-sensitive adhesive layer 1b, the surface of the base film 1a is preferably subjected to treatment such as corona discharge, electron beam irradiation, sputtering, and easy adhesion treatment.

  As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 1b, a known re-peeling pressure-sensitive adhesive ((meth) acrylic, rubber-based, synthetic rubber-based, etc.) can be used without particular limitation. Of these, a (meth) acrylic pressure-sensitive adhesive whose adhesive force is easily controlled by the composition is preferred. In order to provide excellent tackiness, the pressure-sensitive adhesive layer is preferably cross-linked.

  As the (meth) acrylic adhesive, the base polymer preferably has a weight average molecular weight of about 300,000 to 2.5 million. As a monomer used for the (meth) acrylic polymer which is the base polymer of the (meth) acrylic pressure-sensitive adhesive, various alkyl (meth) acrylates can be used. Examples of the alkyl (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like alone or Can be used in combination.

  The (meth) acrylic pressure-sensitive adhesive uses a copolymer obtained by copolymerizing a functional group-containing monomer with the (meth) acrylic polymer as a base polymer, and a crosslinking agent that undergoes a crosslinking reaction with the functional group of the functional group-containing monomer is blended. Those are preferred.

  Examples of the monomer having a functional group include monomers containing a carboxyl group, a hydroxyl group, an epoxy group, amino and the like. Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, N-methylol (meth) acrylamide, and other monomers containing an epoxy group such as glycidyl ( And (meth) acrylate.

  The (meth) acrylic polymer can be copolymerized with an N element-containing monomer. N element-containing monomers include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, (meth) acryloylmorpholine, (meth) acetonitrile, vinylpyrrolidone, N-cyclohexylmaleimide Itaconimide, N, N-dimethylaminoethyl (meth) acrylamide and the like. In addition, as the (meth) acrylic polymer, vinyl acetate, styrene, or the like can be used as long as the performance of the pressure-sensitive adhesive is not impaired. These monomers can be used alone or in combination of two or more.

  Although the ratio of the copolymerization monomer in the (meth) acrylic polymer is not particularly limited, the copolymerization monomer is about 0.1 to 12 parts by weight with respect to 100 parts by weight of the alkyl (meth) acrylate, The amount is preferably 0.5 to 10 parts by weight.

  Examples of the crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, and a metal chelate crosslinking agent. Examples of the crosslinking agent include polyamine compounds, melamine resins, urea resins, and epoxy resins. Of the crosslinking agents, epoxy-based crosslinking agents are preferred. The blending ratio of the crosslinking agent with respect to the (meth) acrylic polymer is not particularly limited, but is usually 0.01 to 10 parts by weight of the crosslinking agent (solid content) with respect to 100 parts by weight of the (meth) acrylic polymer (solid content). Is preferable, and more preferably 1 to 7 parts by weight.

  Examples of the rubber-based pressure-sensitive adhesive include natural rubber, polyisoprene rubber (IR), butyl rubber (IIR), polyisobutylene rubber, styrene-imprene-styrene block copolymer and hydrogenated product thereof, and styrene-butadiene-styrene block copolymer. It can be obtained by blending a rubber component such as a polymer and its hydrogenated product with a softener, a tackifier, a crosslinking (vulcanizing) agent, an anti-aging agent, a filler and the like. As the tackifier, petroleum resin, phenol resin, rosin resin, terpene resin and the like can be used. Although the compounding quantity of a tackifier is not specifically limited, It is 1-200 weight part per 100 weight part of rubber | gum, Preferably it is 10-170 weight part.

  As the crosslinking (vulcanizing) agent, an isocyanate crosslinking agent, a thiuram vulcanizing agent, a quinoid vulcanizing agent, a quinone dioxime vulcanizing agent, a maleimide vulcanizing agent, or the like can be used. The amount of the crosslinking (vulcanizing) agent is not particularly limited, but is 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight per 100 parts by weight of rubber.

  The surface protective film of the present invention contains silicone oil in the pressure-sensitive adhesive layer. As the silicone oil, liquid or fluid dimethylpolysiloxane (weight average molecular weight, for example, 1000 to 10000, preferably 1500 to 8000) can be used. The silicone oil may be a modified silicone oil in which various organic groups are introduced into part of the methyl group of dimethylpolysiloxane.

  Examples of the modified silicone oil include reactive silicone oils such as amino modification, epoxy modification, carboxyl modification, carbinol modification, methacryl modification, mercapto modification, and phenol modification, polyether modification, methylstyryl modification, alkyl modification, and higher alkoxy. Non-reactive silicone oils such as modified and fluorine-modified may be mentioned.

  Of the modified silicone oil, it is preferable to add a carbinol-modified silicone oil in which a part of the methyl group of dimethylpolysiloxane is substituted with a hydroxyalkyl group having 1 to 5 carbon atoms, and more preferably 2 to 4 carbon atoms. Substituted with a hydroxyalkyl group.

Alternatively, among the modified silicone oils, fluorine-modified silicone oils are preferable, and fluorine-modified silicone oils in which a part of methyl groups of dimethylpolysiloxane is substituted with —CH ₂ CH ₂ CF ₃ groups are particularly preferable. Commercially available fluorine-modified silicone oils such as FL-5, FL-10, FL-100, X-22-821, X-22-822 manufactured by Shin-Etsu Chemical Co., Ltd. can be used. Is mentioned.

  The silicone oil is preferably added in an amount of 0.01 to 5 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. When it is less than 0.01 part by weight, the effect of imparting slipperiness is insufficient, and when it exceeds 5 parts by weight, surface contamination tends to occur.

  Furthermore, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, and the like can be used as appropriate for the pressure-sensitive adhesive.

  The method for forming the pressure-sensitive adhesive layer 1b is not particularly limited, and is a method in which a pressure-sensitive adhesive composition is applied to a release liner, dried and transferred to the base film 1a (transfer method), and directly to the base film 1a. Examples thereof include a method of applying and drying the composition (direct copying method) and a method by coextrusion.

  Although the thickness in particular of the adhesive layer 1b is not restrict | limited, About 3-100 micrometers is preferable and about 5-40 micrometers is more preferable. When the thickness of the pressure-sensitive adhesive layer 1b is too thin, it is difficult to form a coating and the adhesive force tends to be insufficient. If the thickness is too thick, the adhesive strength tends to be too high, which tends to be disadvantageous in terms of cost.

  In addition, the surface protection film 1 of this invention can protect the said adhesive layer 1b with a separator, and can also wind in roll shape, when the mold release property of the base film 1a is favorable. Further, the surface protective film 1 may be subjected to antistatic treatment by ordinary means in order to prevent dust adhesion and the like.

  On the other hand, the transparent conductive film 2 protected by the surface protective film 1 of the present invention is, for example, as shown in FIG. That is, as shown in FIG. 1, the transparent conductive film of the present invention comprises a conductive thin film 2b on one side of the base film 2a and a hard coat layer 2c (or anti-glare layer) on the other side, as well as surface protection. The pressure-sensitive adhesive layer 1b of the film 1 is adhered to the surface of the hard coat layer 2c (or anti-glare layer). Or while providing the electroconductive thin film 2b on the single side | surface side of the base film 2a, the adhesive layer 1b of the surface protection film 1 is stuck on the surface of the other surface side of the base film 2a.

  The conductive thin film 2b is formed of a metal oxide thin film such as ITO (indium / tin oxide), tin / antimony, zinc, tin oxide, or an ultrathin metal such as gold, silver, palladium, or aluminum. Is done. These are formed by vacuum deposition, ion beam deposition, sputtering, ion plating, or the like. The thickness of the conductive thin film 2b is not particularly limited, but is generally 50 mm or more, preferably 100 to 2000 mm.

  As the base film 2a, a film made of a transparent material is usually used. Examples of such transparent materials include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polymethyl methacrylate, styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin), and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefins such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, poly Ether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above-mentioned polymer Examples include blends.

  Although the thickness in particular of the base film 2a is not restrict | limited, Generally, it is about 20-130 micrometers, Preferably it is 30-80 micrometers.

  The hard coat layer 2c may be one having only a hard coat function, one having an anti-glare function at the same time, or one having an anti-glare layer on the surface of the hard coat layer 2c.

  As the hard coat agent used, ordinary ultraviolet (UV) and electron beam curable paints, silicone hard coat agents, phosphazene resin hard coat agents, etc. can be used. In view of the degree of freedom, a UV curable paint is preferable. UV curable paints include vinyl polymerization type, polythiol / polyene type, epoxy type, amino alkyd type, and are classified into alkyd, polyester, polyether, acrylic, urethane, and epoxy types according to prepolymer type. Any type can be used.

  Further, the antiglare layer refers to a layer having functions such as glare prevention and reflection prevention. Specifically, for example, those using a difference in refractive index between layers, those using a difference in refractive index with the contained fine particles, and those having a surface with fine irregularities are included.

  The transparent conductive film 2 of the present invention can be used for, for example, a new display system such as a liquid crystal display and an electroluminescence display, a transparent electrode in a touch panel, a sensor, a solar cell, etc., as well as an antistatic or electromagnetic wave shielding of a transparent article. .

  On the other hand, the display device of the present invention is provided with a hard coat layer or an antiglare layer on the surface of the display portion, but the surface protective film of the present invention is adhered to the surface of a display device without a hard coat layer or an antiglare layer. It is also possible to use it. Further, the display device to be attached is not limited to the one provided with the transparent conductive film as described above, but may be one provided with a non-conductive transparent film or glass on the surface. Examples of the display device that does not include the transparent conductive film include an electromagnetic induction touch panel.

  The electromagnetic induction method is a method of receiving the electromagnetic energy on the panel side by touching with a special pen capable of generating a magnetic field and detecting the position of the pen, and a display device (for example, a tablet) including a tablet as a coordinate input device. Used in PC LCD panels). The display device of the present invention includes these.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

Example A
The following acrylic pressure-sensitive adhesive was applied to the non-antistatic surface of a polyester film with a single-side antistatic layer (Mitsubishi Chemical Polyester Co., Ltd., T100G, thickness 38 μm) so that the thickness after drying was 20 μm, and 90 ° C. And dried to obtain a surface protective film.

<Acrylic adhesive>
By ordinary solution polymerization, an acrylic polymer having a weight average molecular weight of 600,000 was obtained with butyl acrylate / acrylic acid = 100/5 (weight ratio). To 100 parts by weight of this acrylic polymer, 6 parts by weight of an epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C) and carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001) 1 A part by weight was added to obtain a pressure-sensitive adhesive composition.

Comparative Example A
In Example A, a surface protective film was obtained in the same manner as in Example A except that no carbinol-modified silicone oil was used.

〔Evaluation test〕
(1) Adhesive strength On the hard coat surface of an ITO film (Nitto Denko Co., Ltd., G400L-TMP) as an adherend, the adhesive layers of the surface protective films of Examples and Comparative Examples were laminators (linear pressure 78. 5 N / cm, with a speed of 0.3 m / min), and after 30 minutes at room temperature, the adhesive force at 180 ° (peeling angle) at a tensile speed of 0.3 m / min and a tensile speed of 10 m / min (N / 20 mm). Moreover, the adhesive layer of the surface protective film of an Example and a comparative example is bonded together on the hard coat surface of the said ITO film with a laminator (linear pressure 78.5 N / cm, speed 0.3 m / min), and it is 150 degreeC after that. Heated for 1 hour. After cooling to room temperature, the same measurement as described above was performed. The results are shown in Table 1.

(2) Contamination The adhesive layer of the surface protective film of Examples and Comparative Examples was bonded to the hard coat surface of the ITO film with a hand roller, and the surface protective film was peeled off after 30 minutes at room temperature. The condition of the hard coat surface was visually confirmed using a green lamp and evaluated according to the following criteria. Moreover, the adhesive layer of the surface protection film of an Example and a comparative example was bonded together on the hard coat surface of the said ITO film with the hand roller, and it heated at 150 degreeC after that for 1 hour. After cooling to room temperature, it was evaluated by the same method as described above. The results are shown in Table 1.
○: No difference is observed on the surface of the hard coat before and after the surface protective film is applied.
X: A difference is observed on the surface of the hard coat before and after the surface protective film is attached.

(3) Sliding property The adhesive layers of the surface protective films of Examples and Comparative Examples were bonded to the hard coat surface of the ITO film with a laminator (linear pressure: 78.5 N / cm, speed: 0.3 m / min). After 30 minutes, the surface protective film was peeled off, and the hard coat surface after peeling was rubbed with a PDA (Palm Computing Co., Ltd., Palm Vx) touch pen to evaluate the sensitive slipperiness according to the following criteria. Moreover, the adhesive layer of the surface protective film of an Example and a comparative example is bonded together on the hard coat surface of the said ITO film with a laminator (linear pressure 78.5 N / cm, speed 0.3 m / min), and it is 150 degreeC after that. Heated for 1 hour. After cooling to room temperature, it was evaluated by the same method as described above. The results are shown in Table 1.
○: The sliding property of the hard coat surface is equal or improved before and after the surface protective film is attached.
X: The slipperiness of the hard coat surface is deteriorated before and after the surface protective film is attached.

表１の結果が示すように、本発明の表面保護フィルムを用いた場合には、ハードコート処理面の滑り性が悪化することがない。さらに、粘着力や汚染性も満足できるものである。

As shown in the results of Table 1, when the surface protective film of the present invention is used, the slipperiness of the hard coat treated surface is not deteriorated. Furthermore, the adhesive strength and contamination are satisfactory.

Example 1
A low-density polyethylene film having a thickness of 60 μm was obtained with a low-density polyethylene resin (Tosoh Co., Ltd., Petrocene 180) using a blow molding machine at a die temperature of 160 ° C. One side of the low-density polyethylene film is subjected to corona treatment, and an acrylic pressure-sensitive adhesive containing the following silicone oil is applied to the corona-treated surface so that the thickness after drying is 2 μm and dried at 80 ° C. A protective film was obtained.

<Acrylic adhesive>
By ordinary solution polymerization, an acrylic polymer having a weight average molecular weight of 600,000 was obtained with butyl acrylate / acrylic acid = 100/5 (weight ratio). With respect to 100 parts by weight of this acrylic polymer, 6 parts by weight of an epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C), and carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001, weight) An average molecular weight of 2000) 3 parts by weight was added to prepare an adhesive composition.

Example 2
A low-density polyethylene film having a thickness of 60 μm was obtained with a low-density polyethylene resin (Tosoh Co., Ltd., Petrocene 180) using a blow molding machine at a die temperature of 160 ° C. One side of the low-density polyethylene film is subjected to corona treatment, and an acrylic adhesive containing the following silicone oil is applied to the corona-treated surface so that the thickness after drying is 10 μm, and the surface is dried at 80 ° C. A protective film was obtained.

<Acrylic adhesive>
By ordinary solution polymerization, an acrylic polymer having a weight average molecular weight of 600,000 was obtained with 2-ethylhexyl acrylate / vinyl acetate / acrylic acid = 100/80/5 (weight ratio). 2 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C) and carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001) 1 per 100 parts by weight of this acrylic polymer A part by weight was added to obtain a pressure-sensitive adhesive composition.

Example 3
A polypropylene film having a thickness of 40 μm at a die temperature of 250 ° C. was obtained by a T-die method using a polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., Nobrene PP AS171G). One side of the polypropylene film is subjected to corona treatment, coated with a long-chain alkyl (on the other hand, Pyroyl 1010, manufactured by Yushi Kogyo Co., Ltd.) as a release treatment agent on the corona-treated surface, dried at 65 ° C., and then non-long chain A rubber adhesive containing the following silicone oil was applied to the alkyl surface so that the thickness after drying was 15 μm and dried at 80 ° C. to obtain a surface protective film.

<Rubber adhesive>
1 part by weight of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001) was added to 100 parts by weight of polyisobutylene having a molecular weight of 800,000 to obtain a pressure-sensitive adhesive composition.

Example 4
In Example 3, a surface protective film was obtained in the same manner as in Example 3 except that 3 parts by weight was added instead of 1 part by weight of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001). .

Example 5
In Example 1, the thickness of the adhesive was 5 μm, and instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001), fluorine-modified silicone oil (FL-5 manufactured by Shin-Etsu Chemical Co., Ltd.), weight A surface protective film was obtained in the same manner as in Example 1 except that 0.2 part by weight of (average molecular weight 6000) was added.

Example 6
In Example 2, the thickness of the adhesive was 5 μm, and instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001), fluorine-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., FL-5) A surface protective film was obtained in the same manner as in Example 2 except that 0.2 part by weight was added.

Example 7
In Example 3, instead of carbinol-modified silicone oil (Shin-Etsu Chemical Co., Ltd., KF-6001), 1 part by weight of fluorine-modified silicone oil (Shin-Etsu Chemical Co., Ltd., FL-5) was added. Obtained a surface protective film in the same manner as in Example 3.

Example 8
In Example 4, instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001), 3 parts by weight of fluorine-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., FL-5) was added. Obtained a surface protective film in the same manner as in Example 4.

Comparative Example 1
In Example 1, the thickness of the pressure-sensitive adhesive was 5 μm, and 1 part by weight of an acrylic oligomer (manufactured by Enomoto Kasei Co., Ltd., 1970) was added instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001). A surface protective film was obtained in the same manner as in Example 1 except that.

Comparative Example 2
Example 2 except that 0.2 parts by weight of an acrylic oligomer (Enomoto Kasei Co., Ltd., 1970) was added instead of carbinol-modified silicone oil (Shin-Etsu Chemical Co., Ltd., KF-6001) in Example 2. In the same manner as in Example 2, a surface protective film was obtained.

Comparative Example 3
Example 3 is the same as Example 3 except that 1 part by weight of an acrylic oligomer (manufactured by Enomoto Kasei Co., Ltd., 1970) is added in place of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001). A surface protective film was obtained in the same manner.

Comparative Example 4
Example 4 is the same as Example 4 except that 3 parts by weight of an acrylic oligomer (manufactured by Enomoto Kasei Co., Ltd., 1970) is added instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001). A surface protective film was obtained in the same manner.

Comparative Example 5
In Example 1, the thickness of the pressure-sensitive adhesive was 10 μm, and instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001), a perfluoroalkyl group-containing oligomer (manufactured by Dainippon Ink Co., Ltd., F- 470) A surface protective film was obtained in the same manner as in Example 1 except that 3 parts by weight were added.

Comparative Example 6
In Example 2, the thickness of the pressure-sensitive adhesive was 5 μm, and instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001), a perfluoroalkyl group-containing oligomer (manufactured by Dainippon Ink Co., Ltd., F- 470) A surface protective film was obtained in the same manner as in Example 2 except that 1 part by weight was added.

Comparative Example 7
In Example 3, 1 part by weight of a perfluoroalkyl group-containing oligomer (Dainippon Ink Co., Ltd., F-470) was added instead of carbinol-modified silicone oil (Shin-Etsu Chemical Co., Ltd., KF-6001). A surface protective film was obtained in the same manner as in Example 3 except that.

Comparative Example 8
In Example 4, instead of carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001), 3 parts by weight of a perfluoroalkyl group-containing oligomer (manufactured by Dainippon Ink Co., Ltd., F-470) was added. A surface protective film was obtained in the same manner as in Example 4 except that.

Comparative Example 9
In Example 1, a surface protective film was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive was 5 μm and carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001) was not used.

Comparative Example 10
In Example 2, a surface protective film was obtained in the same manner as in Example 2 except that the pressure-sensitive adhesive had a thickness of 3 μm and no carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001) was used.

Comparative Example 11
In Example 3, a surface protective film was obtained in the same manner as in Example 3 except that the pressure-sensitive adhesive had a thickness of 13 μm and carbinol-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6001) was not used.

〔Evaluation test〕
(1) Sliding property The pressure-sensitive adhesive layers of the surface protective films of Examples and Comparative Examples are laminated on a hard coat surface of an ITO film (manufactured by Nitto Denko Corporation, 300L-KMP) as an adherend. The surface protective film was peeled off after 30 minutes at room temperature, and the slidability (friction force) of the hard coat surface after peeling was evaluated. The frictional force is placed with the pen tip down on the hard coat surface where a jig with three pen tips of a touch pen (manufactured by Sony Corporation, PEGA-ST61) attached to a 160 g weight is placed on a horizontal base. The resistance force when pulled at a pulling speed of 0.3 m / min was defined as a friction force. The results are shown in Table 2.
◯: When the blank (the hard coat surface of the ITO film before applying the surface protective film) is less than the smoothness (0.4N).
X: When larger than blank smoothness (0.4N).

(2) Contamination A small piece of polypropylene (φ0.5mm) is placed at the center of the hard coat surface of the ITO film so that the hard coat surface and the surface protective film do not contact only at the small piece portion. The adhesive layer of the surface protective film of the example and the comparative example (about 50 mm × 50 mm) was attached with a finger so that the small piece would be in the center of the protective film, and the surface protective film was peeled off after 1 hour at room temperature. The subsequent hard coat surface condition was visually confirmed under a fluorescent lamp against a black background in a dark room, and evaluated according to the following criteria.
The results are shown in Table 2.
◯: There is no difference between the part where the surface protective film is applied and the part where the surface protective film is not attached (part where a small piece is inserted).
X: A difference is observed between the part where the surface protective film is applied and the part where the surface protective film is not attached (part where a small piece is inserted).

(3) Comprehensive evaluation A case where both the slipping property and the contamination property were good was evaluated as ○, and a case where either one was defective was evaluated as ×.

表２の結果が示すように、本発明の表面保護フィルムを用いた場合には、ハードコート処理面の滑り性が悪化することがなく、汚染性も満足できるものである。これに対して、アクリルオリゴマーを用いた比較例１〜４では滑り性が悪化した。また、パーフルオロアルキル基含有オリゴマーを用いた比較例５〜８では、滑り性が良いものも有るが、汚染性が満足できない。更に、シリコーンオイル等の添加剤を用いない比較例９〜１１では、滑り性が悪化した。

As shown by the results in Table 2, when the surface protective film of the present invention is used, the slipperiness of the hard coat treated surface is not deteriorated, and the contamination is satisfactory. On the other hand, in Comparative Examples 1 to 4 using an acrylic oligomer, the slipperiness deteriorated. Moreover, in Comparative Examples 5 to 8 using the perfluoroalkyl group-containing oligomer, there are some which have good slipping property, but the contamination property cannot be satisfied. Further, in Comparative Examples 9 to 11 in which no additive such as silicone oil was used, the slipperiness deteriorated.

Sectional drawing which shows an example of the use condition of the surface protection film of this invention Sectional drawing which shows the other example of the use condition of the surface protection film of this invention Sectional drawing which shows an example of the transparent conductive film which does not use a surface protection film

Explanation of symbols

1: Surface protective film 1a: Base film 1b: Adhesive layer 2: Transparent conductive film 2a: Base film 2b: Conductive thin film 2c: Hard coat layer

Claims (9)

  A surface protective film for protecting the surface of a display unit of a display device, wherein a pressure-sensitive adhesive layer is provided on one side of the base film, and the pressure-sensitive adhesive layer contains silicone oil. the film.   A surface protective film for protecting a surface of a transparent conductive film opposite to a conductive thin film, wherein a pressure-sensitive adhesive layer is provided on one side of the base film, and the pressure-sensitive adhesive layer contains silicone oil A surface protective film characterized by that.   The surface protection film according to claim 1 or 2, wherein the silicone oil is a carbinol-modified silicone oil in which a part of methyl group of dimethylpolysiloxane is substituted with a hydroxyalkyl group having 1 to 5 carbon atoms. The silicone oil, the surface protective film according to claim 1 or 2 a part of methyl groups of dimethyl polysiloxane is a fluorine-modified silicone oil was replaced by -CH ₂ CH ₂ CF ₃ group.   The surface-protective film according to claim 1, wherein the pressure-sensitive adhesive layer contains a (meth) acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive as a main component.   The said adhesive layer is a surface protection film in any one of Claims 1-4 containing the crosslinked body which consists of a (meth) acrylic-type polymer and a crosslinking agent.   A conductive thin film is provided on one side of the base film and a hard coat layer or an antiglare layer is provided on the other side, and the adhesive layer of the surface protective film according to any one of claims 2 to 6, wherein the hard coat layer or A transparent conductive film that is adhered to the surface of the antiglare layer. A transparent film formed by providing a conductive thin film on one side of the base film, and sticking the pressure-sensitive adhesive layer of the surface protective film according to any one of claims 2 to 6 to the surface of the other side of the base film. Conductive film. A hard coat layer or an antiglare layer is provided on the surface of the display unit of the display device, and the pressure-sensitive adhesive layer of the surface protective film according to any one of claims 1 or 3 to 6 is a surface of the hard coat layer or the antiglare layer. A display device attached to the screen.

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