JP2013035977A - Surface protection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new surface protection film, which is capable of achieving sufficiently high antistatic characteristics and wettability, and furthermore, has excellent reworkability (lightly peelable).SOLUTION: This surface protection film, having a base material layer and a pressure-sensitive adhesive layer, contains an alkali metal salt in the pressure-sensitive adhesive layer.

Description

  The present invention relates to a surface protective film. The surface protective film of the present invention has a base material layer and a pressure-sensitive adhesive layer, and is used for applications such as affixing to the surface of a display member or an image recognition member to protect the surface.

  A surface protective film may be bonded to the surface of the display member or the image recognition member in order to prevent scratches or dirt on the surface.

  Such a surface protective film is often bonded manually. Thus, in the case of pasting together by hand, there is a problem that air bubbles are often involved between the adherend and the surface protective film.

  A plasticizer is added to the adhesive layer of the surface protection film as a technique to prevent air bubbles from being caught between the adherend and the surface protection film when the adherend and the surface protection film are bonded manually. Thus, a technique for improving wettability has been reported (Patent Document 1).

  Furthermore, when the adherend and the surface protective film are bonded together by hand, anti-static properties are often required in addition to wettability. Since the same surface protective film is often manually bonded and peeled many times, peeling of the adherend occurs when the protective film is peeled off in the case of an adherend that has not been subjected to antistatic treatment. The charged voltage increases and causes problems.

  For example, foreign matter collects on the adherend and contaminates the optical member. Further, in the case of an optical member such as a polarizing plate, when applied to the liquid crystal with a large amount of static electricity, the alignment of liquid crystal molecules is lost or the panel is lost.

JP 2010-209324 A

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to produce sufficiently high wettability without entrainment of bubbles, reworkability (light releasability), and during peeling. An object of the present invention is to provide a novel surface protective film having excellent antistatic properties.

The surface protective film of the present invention is
A surface protective film having a base material layer and an adhesive layer,
An alkali metal salt is contained in the pressure-sensitive adhesive layer.

  In preferable embodiment, the content rate in the said adhesive layer of the said alkali metal salt is 0.04-0.3 weight%.

  In preferable embodiment, the peeling band voltage of the said adhesive layer is 0.7 kV or less.

In preferable embodiment, the wetting speed | rate with respect to an acrylic board in the surface which contacts the adherend of the said adhesive layer is 5.0 cm < ² > / sec or more.

  In preferable embodiment, the adhesive force with respect to an acrylic board in the surface which contacts the adherend of the said adhesive layer is 0.02-0.5 N / 25mm.

  In a preferred embodiment, the surface protective film of the present invention is used on the surface of a display member or an image recognition member.

The present invention also provides a display member.
The display member of the present invention is covered with the surface protective film of the present invention.

The present invention also provides an image recognition member.
The image recognition member of the present invention is covered with the surface protective film of the present invention.

  According to the present invention, by including an alkali metal salt in the pressure-sensitive adhesive, a sufficiently high antistatic property can be expressed, a sufficiently high wettability can be expressed, and reworkability (light release property) is also excellent. A novel surface protective film can be provided.

It is a schematic sectional drawing of the surface protection film by preferable embodiment of this invention. It is a schematic sectional drawing which shows the state before bonding of the acrylic board and test piece in the measurement of a wetting speed.

≪A. Surface protection film >>
The surface protective film of the present invention includes a base material layer and an adhesive layer. FIG. 1 is a schematic cross-sectional view of a surface protective film according to a preferred embodiment of the present invention. The surface protective film 10 includes a base material layer 1 and an adhesive layer 2. The surface protective film of the present invention may further have any appropriate other layer as required (not shown).

  For the purpose of forming a wound body that can be easily rewound on the surface of the base material layer 1 that is not provided with the pressure-sensitive adhesive layer 2, for example, the base material layer includes a fatty acid amide, polyethyleneimine, and a long-chain alkyl series. A release treatment can be performed by adding an additive or the like, or a coating layer made of any appropriate release agent such as silicone, long-chain alkyl, or fluorine can be provided.

  The surface protective film of the present invention may be bonded with a release liner having releasability.

  The thickness of the surface protective film of the present invention can be set to any appropriate thickness depending on the application. From the viewpoint of fully expressing the effects of the present invention, the thickness is preferably 10 to 300 μm, more preferably 15 to 250 μm, still more preferably 20 to 200 μm, and particularly preferably 25 to 150 μm.

  In the surface protective film of the present invention, the release voltage of the pressure-sensitive adhesive layer is preferably 0.7 kV or less, more preferably 0.5 kV or less, still more preferably 0.3 kV or less, and particularly preferably 0. 0.2 kV or less, and most preferably 0.1 kV or less. If the release voltage of the pressure-sensitive adhesive layer is within the above range, the surface protective film of the present invention can exhibit sufficiently high antistatic properties, sufficiently high wettability, and reworkability (light release properties). ) Is also excellent. The measurement of the stripping voltage will be described later.

In the surface protective film of the present invention, the wetting speed with respect to the acrylic plate on the surface of the pressure-sensitive adhesive layer in contact with the adherend is preferably 5.0 cm ² / sec or more, more preferably 10 cm ² / sec or more, More preferably, it is 15 cm ² / sec or more, particularly preferably 20 cm ² / sec or more, and most preferably 30 cm ² / sec or more. The upper limit value of the wetting rate is not particularly limited, but in reality, it is preferably 1000 cm ² / sec or less, more preferably 100 cm ² / sec or less. If the wetting speed for the acrylic plate on the surface of the pressure-sensitive adhesive layer in contact with the adherend is within the above range, the surface protective film of the present invention can exhibit sufficiently high wettability. The measurement of the wetting rate will be described later.

  In the surface protective film of the present invention, the adhesive force to the acrylic plate on the surface of the pressure-sensitive adhesive layer in contact with the adherend is preferably 0.02 to 0.5 N / 25 mm, more preferably 0.02 to 0.00. It is 4N / 25mm, More preferably, it is 0.02-0.3N / 25mm. If the adhesive force with respect to an acrylic board in the surface which contact | connects the to-be-adhered body of an adhesive layer exists in the said range, the surface protection film of this invention is excellent in rework property (light peelability). The measurement of the adhesive strength will be described later.

<A-1. Base material layer>
Any appropriate thickness can be adopted as the thickness of the base material layer depending on the application. The thickness of the base material layer is preferably 5 to 300 μm, more preferably 10 to 250 μm, still more preferably 15 to 200 μm, and particularly preferably 20 to 150 μm.

  The base material layer may be a single layer or a laminate of two or more layers. The base material layer may be stretched.

  Any appropriate material can be adopted as the material of the base material layer depending on the application. For example, a plastic, paper, a metal film, a nonwoven fabric, etc. are mentioned. Preferably, it is a plastic. The base material layer may be composed of one kind of material, or may be composed of two or more kinds of materials. For example, you may be comprised from 2 or more types of plastics.

  Examples of the plastic include a polyester resin, a polyamide resin, and a polyolefin resin. Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin resin include olefin monomer homopolymers, olefin monomer copolymers, and the like. Specific examples of polyolefin resins include homopolypropylene; block-type, random-type, and graft-type propylene copolymers having an ethylene component as a copolymer component; reactor TPO; low density, high density, linear Low density, ultra-low density, etc. ethylene polymers; ethylene / propylene copolymer, ethylene / vinyl acetate copolymer, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / acrylic acid And ethylene copolymers such as butyl copolymer, ethylene / methacrylic acid copolymer, and ethylene / methyl methacrylate copolymer.

  The base material layer may contain any appropriate additive as required. Examples of the additive that can be contained in the base material layer include an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a filler, and a pigment. The kind, number, and amount of additives that can be contained in the base material layer can be appropriately set according to the purpose. In particular, when the material of the base material layer is plastic, it is preferable to contain some of the above additives for the purpose of preventing deterioration. From the viewpoint of improving weather resistance and the like, particularly preferred additives include antioxidants, ultraviolet absorbers, light stabilizers, and fillers.

  Any appropriate antioxidant can be adopted as the antioxidant. Examples of such antioxidants include phenol-based antioxidants, phosphorus-based processing heat stabilizers, lactone-based processing heat stabilizers, sulfur-based heat-resistant stabilizers, phenol-phosphorus-based antioxidants, and the like. The content of the antioxidant is preferably 1 part by weight or less with respect to 100 parts by weight of the base resin of the base layer (when the base layer is a blend, the blend is the base resin), More preferably, it is 0.5 weight part or less, More preferably, it is 0.01-0.2 weight part.

  Arbitrary appropriate ultraviolet absorbers can be employ | adopted as a ultraviolet absorber. Examples of such UV absorbers include benzotriazole UV absorbers, triazine UV absorbers, and benzophenone UV absorbers. The content of the ultraviolet absorber is preferably 2 parts by weight or less with respect to 100 parts by weight of the base resin forming the base layer (when the base layer is a blend, the blend is the base resin). More preferably 1 part by weight or less, still more preferably 0.01 to 0.5 part by weight.

  Any appropriate light stabilizer can be adopted as the light stabilizer. Examples of such light stabilizers include hindered amine light stabilizers and benzoate light stabilizers. The content ratio of the light stabilizer is preferably 2 parts by weight or less with respect to 100 parts by weight of the base resin forming the base layer (in the case where the base layer is a blend, the blend is the base resin). More preferably 1 part by weight or less, still more preferably 0.01 to 0.5 part by weight.

  Any appropriate filler can be adopted as the filler. Examples of such fillers include inorganic fillers. Specific examples of the inorganic filler include carbon black, titanium oxide, and zinc oxide. The content of the filler is preferably 20 parts by weight or less with respect to 100 parts by weight of the base resin forming the base layer (when the base layer is a blend, the blend is the base resin). More preferably, it is 10 weight part or less, More preferably, it is 0.01-10 weight part.

  Furthermore, as the additive, for the purpose of imparting antistatic properties, inorganic, low molecular weight and high molecular weight antistatic agents such as surfactants, inorganic salts, polyhydric alcohols, metal compounds, carbon and the like are also preferred. In particular, a high molecular weight antistatic agent and carbon are preferable from the viewpoint of contamination and adhesiveness maintenance.

<A-2. Adhesive layer>
The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive. Only one type of adhesive may be used, or two or more types may be used.

  The pressure-sensitive adhesive preferably contains polymer P as a main component. The content ratio of the polymer P in the pressure-sensitive adhesive is preferably 50% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

  The polymer P may be a crosslinked polymer.

  Arbitrary appropriate adhesives can be employ | adopted for the adhesive which comprises an adhesive layer. Examples of such adhesives include silicone adhesives, urethane adhesives, acrylic adhesives, rubber adhesives, and the like. From the viewpoint that the effects of the present invention can be further exhibited, the pressure-sensitive adhesive is preferably a silicone-based pressure-sensitive adhesive or a urethane-based pressure-sensitive adhesive.

  Arbitrary appropriate silicone adhesives can be employ | adopted as a silicone adhesive. As such a silicone-based pressure-sensitive adhesive, one obtained by blending or agglomerating a silicone resin can be preferably used.

  Examples of the silicone pressure sensitive adhesive include addition reaction curable silicone pressure sensitive adhesives and peroxide curable silicone pressure sensitive adhesives. Among these silicone pressure-sensitive adhesives, peroxides (benzoyl peroxide and the like) are not used, and decomposition products are not generated. Therefore, an addition reaction curable silicone pressure-sensitive adhesive is preferable.

  As a curing reaction of the addition reaction curable silicone pressure-sensitive adhesive, for example, when obtaining a polyalkyl silicone pressure-sensitive adhesive, generally, a method of curing a polyalkylhydrogensiloxane composition with a platinum catalyst can be mentioned.

  Any appropriate urethane-based pressure-sensitive adhesive can be adopted as the urethane-based pressure-sensitive adhesive. As such a urethane type adhesive, Preferably, what consists of urethane resin obtained by making a polyol and a polyisocyanate compound react is mentioned. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and the like.

  The pressure-sensitive adhesive layer contains an alkali metal salt. By including an alkali metal salt in the pressure-sensitive adhesive layer, the surface protective film of the present invention can exhibit sufficiently high antistatic properties, sufficiently high wettability, and reworkability (light peelability). Also excellent.

  The content of the alkali metal salt in the pressure-sensitive adhesive layer is preferably 0.04 to 0.3% by weight. If the content ratio of the alkali metal salt in the pressure-sensitive adhesive layer is within the above range, the surface protective film of the present invention can exhibit sufficiently sufficiently high antistatic properties and wettability, and further, reworkability (light release property). Even better.

Any appropriate alkali metal salt can be adopted as the alkali metal salt. Specific examples thereof include metal salts composed of lithium, sodium, and potassium. Specifically, any one of cations composed of Li ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , BF _{^{4 -, PF 6 -, SCN}} -, ClO 4 -, C n F n + 1 SO 3 -, (CF 3 SO 2) 2 n -, (C 2 F 5 SO 2) 2 n -, (SO 2 F ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , and a metal salt composed of any of anions composed of boron-containing compounds are preferably used. Among these, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ A lithium salt such as SO ₂ ) ₃ C is preferably used. These alkali metal salts may be used alone or in combination of two or more.

  Any appropriate additive may be contained in the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer. Examples of such additives include softeners, tackifiers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, heat stabilizers, polymerization inhibitors, silane cups. Examples include ring agents, lubricants, inorganic or organic fillers, metal powders, pigments, and solvents. Moreover, you may add an alkylene oxide group containing compound. Although the reason is not clear, the alkylene oxide group-containing compound can interact with the alkali metal salt and can efficiently exhibit peeling chargeability. Examples of the alkylene oxide group-containing compound include polyether polyol compounds and derivatives thereof, and other polyether-modified compounds. In the present invention, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer preferably does not contain a plasticizer. This is because, when a pressure-sensitive adhesive layer to which a plasticizer is added is used, wettability is improved, but the adherend may be contaminated by the plasticizer.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer can be produced by any appropriate method. As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, for example, a polymerization method generally used as a polymer synthesis method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, polymerization by ultraviolet rays (UV), etc. is used. It can be produced by adopting an appropriate crosslinking method and using any appropriate additive as required.

  The surface protective film of the present invention can be used for any appropriate application. Preferably, the surface protective film of the present invention is used on the surface of a display member or an image recognition member.

  The display member covered with the surface protective film of the present invention can be bonded and peeled many times manually.

  The image recognition member covered with the surface protective film of the present invention can be bonded and peeled many times manually.

≪B. Manufacturing method of surface protective film >>
The surface protective film of the present invention can be produced by any appropriate method. As such a manufacturing method, for example,
(1) A method of applying a solution of a pressure-sensitive adhesive solvent or a hot melt to a substrate,
(2) A method for transferring the pressure-sensitive adhesive layer applied and formed in the form of a separator according to that,
(3) A method of forming and applying an adhesive layer forming material onto a substrate,
(4) A method of extruding a base material and an adhesive layer in two layers or multiple layers,
(5) A method of laminating a pressure-sensitive adhesive layer on a substrate or a method of laminating two layers of pressure-sensitive adhesive layers together with a laminate layer,
(6) A method of laminating a pressure-sensitive adhesive layer and a base material forming material such as a film or a laminate layer in two or multiple layers,
It can be performed according to any appropriate production method.

  Examples of the coating method include a method using a bar coater, a gravure coater, a spin coater, a roll coater, a knife coater, an applicator and the like.

  From the viewpoint of productivity and cost, the method for producing the surface protective film of the present invention is particularly preferably a method of applying a solution of a pressure-sensitive adhesive solvent or a hot melt to a substrate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples at all.

  In addition, the test and evaluation method in an Example etc. are as follows.

(Measurement of peeling voltage)
A surface protective film is cut to a size of 70 mm in width and 130 mm in length, the separator is peeled off, and then the surface of the acrylic panel (Mitsubishi Rayon Co., Ltd., Acrylite) with a thickness of 1 mm, width 70 mm and length 100 mm previously removed. The one end was pressed with a hand roller so that it protruded 30 mm. After being left in an environment of 23 ° C. × 25% RH for one day, one end protruding 30 mm was fixed to an automatic winder, and peeled at a peeling angle of 150 ° and a peeling speed of 10 m / min. The peeled surface protective film was placed on a sample fixing base, and the potential of the pressure-sensitive adhesive layer surface was measured with a potential measuring device (KSD-0103, manufactured by Kasuga Denki Co., Ltd.). The measurement was performed in an environment of 23 ° C. × 25% RH.

(Measurement of wetting speed)
Test piece: 2.5 cm × 8.0 cm
Substrate: Acrylic board (Made by Mitsubishi Rayon, trade name: Acrylite L)
Number of measurements: 3 (adopts average value of 3 independent measurements)
Measurement environment: Class 10000 clean room (temperature 23 ° C, humidity 50% RH)
(1) In FIG. 2, the state before bonding of an acrylic board and a test piece in the measurement of a wetting rate is shown. As shown in FIG. 2, the angle is set to 20 to 30 degrees in a state where a part of the pressure-sensitive adhesive layer surface of the test piece (surface protective film) is in contact with the acrylic plate.
(2) Next, remove the hand from the test piece, attach it only with its own weight, and record the state that the adhesive layer of the test piece spreads on the acrylic plate with a digital camera at the same time as the hand is released. .
(3) The image analysis software “ImageJ” shows how the adhesive layer surface other than the portion in contact with the acrylic plate in (1) touches the acrylic plate as an initial point, and then spreads out every 0.2 seconds. To analyze.
(4) The wetting rate is calculated using the following calculation formula.
Wetting rate ^(cm 2 / sec) = ^(wetted area of 0.2 seconds after the initial point (cm ²⁾ - wetted area of the initial point ^{(cm 2)) / 0.2 (} sec)

(Measurement of adhesive strength)
The surface protective film was cut into a width of 25 mm and a length of 150 mm to obtain a sample for evaluation.
In an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH, the pressure-sensitive adhesive layer surface of the sample for evaluation was attached to an acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acrylite L) by one reciprocation of a 2 kg roller. After curing at 23 ° C. for 30 minutes, the adhesive strength was measured using a universal tensile tester (manufactured by Minebea Co., Ltd., product name: TCM-1kNB) at a peeling angle of 180 ° and a pulling speed of 10 m / min.

[Example 1]
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst 0.015 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.05 part by weight of LiN (CF ₃ SO ₂ ) ₂ (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent And it stirred with the disper and produced the urethane type adhesive composition.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (1) was produced.
The results are shown in Table 1.

[Example 2]
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst 0.015 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.10 parts by weight of LiN (CF ₃ SO ₂ ) ₂ (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent And it stirred with the disper and produced the urethane type adhesive composition.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (2) was produced.
The results are shown in Table 1.

Example 3
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.30 part by weight of LiN (CF ₃ SO ₂ ) ₂ (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent And it stirred with the disper and produced the urethane type adhesive composition.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (3) was produced.
The results are shown in Table 1.

Example 4
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst As a mixture, 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.05 part by weight of LiClO ₄ (manufactured by Wako Pure Chemical Industries, Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent are mixed and stirred with a disper And the urethane type adhesive composition was produced.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (4) was produced.
The results are shown in Table 1.

Example 5
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst As a mixture, 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.10 part by weight of LiClO ₄ (manufactured by Wako Pure Chemical Industries, Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent are mixed and stirred with a disper And the urethane type adhesive composition was produced.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (5) was produced.
The results are shown in Table 1.

Example 6
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst As a mixture, 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.30 part by weight of LiClO ₄ (manufactured by Wako Pure Chemical Industries, Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent are mixed and stirred with a disper And the urethane type adhesive composition was produced.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (6) was produced.
The results are shown in Table 1.

Example 7
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst As a compound, 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.05 part by weight of LiCF ₃ SO ₃ (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent are mixed. Stirring to prepare a urethane-based pressure-sensitive adhesive composition.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (7) was produced.
The results are shown in Table 1.

Example 8
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst As a compound, 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.10 part by weight of LiCF ₃ SO ₃ (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent are mixed. Stirring to prepare a urethane-based pressure-sensitive adhesive composition.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (8) was produced.
The results are shown in Table 1.

Example 9
100 parts by weight of “PREMINOL 7012” (100% solids, manufactured by AGC Asahi Glass Co., Ltd.) as a urethane-based adhesive, 13.2 parts by weight of “Coronate L” (75% solids, manufactured by Nippon Polyurethane Co., Ltd.), a crosslinking catalyst As a compound, 0.015 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution), 0.30 part by weight of LiCF ₃ SO ₃ (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt, and 100 parts by weight of toluene as a solvent are mixed. Stirring to prepare a urethane-based pressure-sensitive adhesive composition.
The obtained urethane-based pressure-sensitive adhesive composition was applied to a base material “Lumirror S10” (thickness 38 μm, manufactured by Toray Industries, Inc.) made of a polyester resin so that the thickness after drying with a fountain roll was 21 μm. It was cured and dried under the condition of a drying time of 1 minute.
Next, the surface of the pressure-sensitive adhesive layer is pasted with a silicone-treated surface of a base material made of a polyester resin having a thickness of 25 μm and subjected to silicone fluoride treatment on one side, and subjected to aging at an aging temperature of 50 ° C. for 2 days, A surface protective film (9) was produced.
The results are shown in Table 1.

[Comparative Example 1]
A surface protective film (C1) was produced in the same manner as in Example 1 except that no alkali metal salt was used.
The results are shown in Table 1.

  The surface protective film of the present invention is suitably used for applications such as affixing to the surface of a display member or an image recognition member to protect the surface.

DESCRIPTION OF SYMBOLS 1 Base material layer 2 Adhesive layer 10 Surface protection film

Claims (8)

A surface protective film having a base material layer and an adhesive layer,
An alkali metal salt is contained in the pressure-sensitive adhesive layer.
Surface protective film.   The surface protection film of Claim 1 whose content rate in the said adhesive layer of the said alkali metal salt is 0.04-0.3 weight%.   The surface protection film of Claim 1 or 2 whose peeling voltage of the said adhesive layer is 0.7 kV or less. The surface protection film according to any one of claims 1 to 3, wherein a wetting speed with respect to the acrylic plate on a surface of the pressure-sensitive adhesive layer in contact with the adherend is 5.0 cm ² / sec or more.   The surface protection film in any one of Claim 1 to 4 whose adhesive force with respect to an acrylic board in the surface which contact | connects the adherend of the said adhesive layer is 0.02-0.5 N / 25mm.   The surface protection film according to any one of claims 1 to 5, which is used on a surface of a display member or an image recognition member.   The display member coat | covered with the surface protection film in any one of Claim 1-6. An image recognition member coated with the surface protective film according to claim 1.