JP2013087163A - Surface protection film, and optical member plastic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protection film, which can be exfoliated excellently from a plastic sheet being an adherend and in which an adhesive and a polypropylene film are used as base materials.SOLUTION: The surface protection film includes: the base material of the polypropylene film; a first adhesive layer formed on the base material; and a second adhesive layer formed on the first adhesive layer; wherein the first adhesive layer has polyolefin polyol as a main component.

Description

The present invention relates to a surface protective film and an optical member plastic sheet having the surface protective film adhered to the surface.

  Various plastic sheets are used as optical members used in display products such as liquid crystal panels and PDP panels.

  Before being assembled as a panel of a display product, a surface protective film is stuck on the surface of these optical member plastic sheets so as not to be stained or damaged during transportation or storage.

  It is necessary that the surface protective film does not peel off without permission or that the adhesive does not remain on the plastic sheet when peeled off.

  Further, the surface shape of the optical member plastic sheet is various, such as a smooth shape, a mat shape, a triangular prism shape, and a kamaboko prism shape. Therefore, even if the surface protective film has the same adhesive force, the force required for peeling becomes stronger or weaker due to the different surface shape of the plastic sheet, which causes a problem in the peeling operation. When the peel strength is different, it is necessary to adjust the automatic machine individually, particularly when the surface protective film is peeled off by the automatic machine.

  Conventionally, Patent Document 1 has been proposed in which a polymer containing an α-olefin is used as a main agent as a pressure-sensitive adhesive for a surface protective film that is adhered to a metal steel plate or the like to protect the surface.

Further, Patent Document 2 in which two types of pressure-sensitive adhesives are laminated is proposed as a surface protective film for a resin plate having an uneven shape.

Japanese Patent No. 3370198 JP 2011-6523 A

  For example, when the optical member plastic sheet is inspected without peeling off the surface protective film in the process of assembling the display panel, it is preferable to use a transparent polypropylene film as the surface protective film.

However, since the optical member plastic sheet is easy to mold and requires transparency, a resin having relatively good adhesion such as an acrylic resin is often used. If an ordinary adhesive is used to adhere the optical member plastic sheet, the adhesive strength of the adhesive to the optical member plastic sheet is greater than the adhesive strength of the adhesive to the polypropylene film. It tends to remain on the sheet.

  Then, this invention makes it a subject to provide the surface protection film which makes a polypropylene film a base material and can be peeled favorably from a to-be-adhered body.

  1st invention is equipped with the base material of a polypropylene film, the 1st adhesion layer formed on this base material, and the 2nd adhesion layer formed on this 1st adhesion layer, The 1st adhesion layer Is a surface protective film characterized by comprising a polyolefin polyol as a main component.

The second invention is an optical member plastic sheet having a convex shape on the surface, and the surface protective film of the first invention adhered to the convex surface, the convexity of the surface of the optical member plastic sheet An optical member plastic sheet characterized in that the shape passes through the second adhesive layer of the surface protective film and penetrates to the first adhesive layer.

  A third invention is the surface protective film according to the first invention, wherein the polyolefin polyol is a hydroxyalkyl vinyl ether polymer or a copolymer of hydroxyalkyl vinyl ether and alkyl vinyl ether.

  A fourth invention is the surface protective film according to the first invention, wherein the polyolefin polyol is a polyolefin polyol crosslinked with a urethane bond.

ADVANTAGE OF THE INVENTION According to this invention, the surface protection film which can make it peel favorably from a to-be-adhered body can be provided which uses a polypropylene film as a base material.

It is a structure sectional view of the surface protection film of the present invention. It is the schematic diagram which stuck the surface protection film on both surfaces of the plastic sheet of the to-be-adhered body. It is the schematic diagram which stuck the surface protection film whose adhesion layer is one layer. A plastic sheet formed on a film.

  The surface protective film of the present invention comprises a polypropylene film substrate, a first adhesive layer formed on the substrate, and a second adhesive layer formed on the first adhesive layer. The layer is based on polyolefin polyol.

  The polyolefin polyol is preferably a hydroxyalkyl vinyl ether polymer or a copolymer of hydroxyalkyl vinyl ether and alkyl vinyl ether. Alternatively, the polyolefin polyol is preferably a polyolefin polyol crosslinked with a urethane bond.

  The surface protective film retains moderate protection against the surface of the adherend, that is, flexibility that does not damage the surface, elongation with time and temperature, scratches, mechanical strength, heat resistance, corrosion resistance, and other physical properties. Is required. The surface protective film of the present invention is excellent in these characteristics because polypropylene is used for the base material.

  Moreover, the surface protection film which can give a certain fixed peeling strength and peeling sensation to the to-be-adhered body surface of various shapes and the to-be-adhered body surface from which average roughness differs is calculated | required. Furthermore, a surface protective film that can be used on both sides with one type of surface protective film is also required for a plastic sheet having a flat surface and a lens surface. The surface protective film of the present invention is formed by forming a first adhesive layer and a second adhesive layer on a polypropylene film substrate, and the first adhesive layer contains a polyolefin polyol.

  In addition, the optical member plastic sheet is subjected to various inspections while the surface protection film is adhered during the assembly process of the display panel. Since the surface protective film of the present invention uses polypropylene having high optical transparency for the substrate, the influence on the inspection is small.

  The optical member plastic sheet is formed by extruding molten acrylic resin from a die having a shape such as a prism. Alternatively, it is molded by embossing an acrylic sheet that is easy to mold by heating.

  Furthermore, a plastic sheet of an optical member having a more precise shape can be formed by applying a resin that is cured by ultraviolet rays or visible light on a polyester (PET) film and exposing the resin while being pressed against a mold. In this case, as shown in FIG. 4, the concavo-convex surface is an acrylic curable resin, and the opposite surface is a plastic sheet of an optical member having a two-layer structure that becomes a polyester film.

  Acrylic pressure sensitive adhesives and pressure sensitive adhesives with polar groups of vinyl acetate are weak in adhesive strength to polypropylene film, but on plastic sheets using acrylic resin, etc., to be adhered. Since it adheres well, when the surface protective film is peeled off, the pressure-sensitive adhesive having a polar group is easily detached from the polypropylene film and remains on the adherend.

The inventors have found that among olefin-based pressure-sensitive adhesives, in particular, pressure-sensitive adhesives mainly composed of polyolefin polyol exhibit good adhesion to polypropylene films.
However, the polyolefin polyol pressure-sensitive adhesive showing good adhesion to polypropylene film did not exhibit sufficient adhesion to the plastic sheet of an optical member formed of an acrylic resin.

  In addition, one side of the plastic sheet of the optical member has a flat plane or a fine matte plane, but the other side has an uneven surface in which triangular prisms and semi-cylinders are arranged side by side. In order to adjust the adhesive strength and peel strength to appropriate values, it was necessary to use an adhesive other than the adhesive mainly composed of polyolefin polyol.

For this purpose, an adhesive mainly composed of polyolefin polyol is provided as a first adhesive layer on a polypropylene film base material, and the adhesive sheet of the optical member exhibits good adhesiveness on the first adhesive layer. The present invention is achieved by providing the second pressure-sensitive adhesive layer with a pressure-sensitive adhesive that protects the surface during transportation and storage and can be easily peeled off during use.

Furthermore, by having a two-layer structure of the first adhesive layer and the second adhesive layer, the peel force hardly changes even if the surface protective film is peeled off from the smooth surface of the adherend or peeled off from the uneven surface. Thus, the present invention has been found.

The present invention will be described below with reference to the drawings. As shown in FIG. 1, the surface protective film 15 is obtained by laminating a first adhesive layer 1 and a second adhesive layer 2 on a base material 11.

FIG. 2 shows the surface protection film 15 of the present invention attached to both surfaces of a plastic sheet 21 of an optical member provided with a plurality of triangular prisms on the sheet surface.

The lower surface of the plastic sheet 21 is often smooth or fine matte, but it is adhered with a second adhesive layer having an appropriate peel strength, and the peel is good.

The upper surface of the plastic sheet has a triangular prism protrusion, and when the adhesive layer is a single layer, the area in contact with the adhesive increases as shown by 2 'in FIG. The force is larger than the force for peeling the surface protective film from the lower surface.

As shown in FIG. 2, the surface protective film of the present invention has a triangular surface of the plastic sheet that bites into the first adhesive layer, so that the area where the second adhesive layer and the triangular prism on the surface of the plastic sheet are in contact with each other is a lower surface with a smooth surface. Compared to the case, it will not be large. In addition, the first adhesive layer adheres firmly to the polypropylene substrate, but does not require extra force during peeling because the adhesive strength is small for the plastic sheet.

In this way, the surface protective film of the present invention can make the force required for peeling substantially equal on the smooth surface or the uneven surface of the plastic sheet of the adherend. Moreover, since the adhesion layer 1 is firmly adhered to the polypropylene film substrate, the adhesive does not remain on the adherend.

Hereinafter, the material used for this invention is demonstrated in detail.
≪Base material≫
The polypropylene film used as the base material can be any film as long as it is transparent and smooth by forming a resin composition mainly composed of molten polypropylene into a predetermined thickness by an inflation method or an extrusion method using a T-die. Available. The thickness is appropriately selected in the range of 30 μm to 200 μm, more preferably 50 to 125 μm.

When a film having no optical retardation is required, an unstretched film formed by an extrusion method using a T die is suitable, and polypropylene polymerized with a metallocene catalyst is suitable for the resin to be used. In addition, the resin film is rarely produced only with the resin as the main component, and may contain other resins, inorganic particles, additives, etc. for adjustment of processability and various physical properties, for example. It is normal. Therefore, the polypropylene film in the present invention means a resin film mainly composed of polypropylene which can be generally called a polypropylene film.

If necessary, the surface of the polypropylene film may be subjected to corona treatment, flame treatment, chemical treatment, or primer treatment in order to increase the adhesive strength with the adhesive.

"First adhesive layer"
≪Polyolefin polyol adhesive≫
The first adhesive layer ensures adhesion between the polypropylene film substrate and the second adhesive layer, and in particular, ensures adhesiveness that is peelable from the surface of the optical member plastic sheet having a convex shape on the surface. In the present invention, a polyolefin polyol is the main component. In order to ensure such adhesion and adhesiveness, the polyolefin polyol is preferably contained in the first adhesive layer at least 50% or more, more preferably 70% or more, and more preferably 90% or more. It is particularly preferred that it is contained.
As the polyolefin polyol, either a polymer or a crosslinked product can be used. Although only a polymer or a crosslinked product can be used, the polymer and the crosslinked product may be mixed. Moreover, you may add a tackifier (tackifier) in order to adjust adhesive strength. In the present invention, the polymer refers to a resin obtained by polymerizing monomers, and the crosslinked body refers to a resin obtained by crosslinking an oligomer or polymer having a functional group.

(Polyolefin polyol polymer)
As the polyolefin polyol polymer, a hydroxyalkyl vinyl ether polymer, a hydroxyalkyl vinyl ether and an alkyl vinyl ether copolymer, or a mixture of both is used. Each polymer is obtained by cationic polymerization of each monomer.

  Examples of the hydroxyalkyl vinyl ether monomer include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 5- Examples thereof include hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, and the like.

  Examples of the alkyl vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2 -Alkyl vinyl ethers having no substituent such as ethylhexyl vinyl ether, alkyl vinyl ethers having substituents other than hydroxy groups such as chloromethyl vinyl ether, chloroethyl vinyl ether, benzyl vinyl ether, phenylethyl vinyl ether, or cyclopentyl vinyl ether, cyclohexyl vinyl ether Or methylcyclohexyl vinyl ether It includes cyclic alkyl vinyl ethers of. Or what has two vinyl groups in a molecule | numerator, such as 4-butanediol divinyl ether and cyclohexane dimethanol divinyl ether, is mentioned.

(Polymerization initiator)
Vinyl ethers are cationically polymerized using Bronsted acid or Lewis acid as an initiator.
For example, in general, inorganic protons such as hydrochloric acid, phosphoric acid, sulfuric acid, odorous acid and hydrogen iodide, organic acids such as formic acid, acetic acid and trifluoroacetic acid, as well as protic solvents such as water and alcohol can coexist the protons. Examples thereof include a metal or a metal compound to be generated. Specifically, proton acids (sulfuric acid, phosphoric acid, hydrochloric acid, odorous acid, nitric acid, hydrogen fluoride, hydrogen iodide, formic acid, acetic acid and its chlorinated products, propionic acid, butyric acid, trifluoroacetic acid, p-toluenesulfonic acid, Metal oxides and other solid acids (chromium oxide, phosphorus oxide, titanium oxide, aluminum oxide, cobalt oxide, manganese oxide, molybdenum oxide, silica-alumina, vanadium oxide, aluminum sulfate, iron sulfate, chromium sulfate, Etc.), halogen (iodine, bromine, chlorine, iodine bromide, iodine chloride, bromine chloride), metal halide (beryllium, magnesium, zinc, cadmium, mercury, boron, aluminum, gallium, titanium, zirconium, tin, phosphorus, Antimony, niobium, bismuth, thallium, uranium, rhenium, iron, bromides, chlorides or fluorides) .

  Alternatively, a Lewis acid catalyst such as boron trifluoride, polymerization in a heterogeneous system using a solid acid such as chromium (III) oxide or silica alumina, sulfate or acidic clay, silicon dioxide and aluminum oxide, magnesium oxide, A catalyst comprising one or more metal oxides selected from iron oxide and titanium oxide can be used.

  Furthermore, as a catalyst for cationic polymerization, heteropolyacids such as phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, borotungstic acid, boromolybdic acid, cobalt molybdic acid, cobalt tungstic acid, arsenic tungstic acid Germanium tungstic acid, phosphorus molybdotungstic acid, boromolybdotungstic acid and the like. Among these, phosphotungstic acid and phosphomolybdic acid are particularly preferable in terms of no coloring, solubility, and polymerization initiation ability.

(Polymerization stabilizer)
In cationic polymerization, various side reactions such as transfer reaction are likely to occur, so that a polymer having a wide molecular weight distribution is easily formed. When a weak base of Lewis base is introduced, the reactive species at the growth end is stabilized, so that side reactions can be suppressed and a polymer having a narrow molecular weight distribution can be obtained.

  Examples of the Lewis base include ester compounds such as ethyl acetate, n-butyl acetate, and phenyl acetate. Examples thereof include pyridine derivatives such as pyridine and 2,6-dimethylpyridy, and amide compounds such as N, N-dimethylacetamide and N, N-dimethylformamide. These Lewis bases can be used alone or in appropriate combination of two or more.

(Polymerization solvent)
Examples of the polymerization solvent include aromatic hydrocarbon solvents such as toluene, xylene, and benzene, aliphatic hydrocarbon solvents such as n-hexane and n-heptane, and halogen-based solvents such as dichloromethane, dichloroethane, and carbon tetrachloride. It is used alone or in combination of two or more. Regarding the polymerization solvent, the addition amount can be determined in accordance with the state of the polymerization system.

As the polymerization temperature, the same conditions as in the usual living cationic polymerization of a vinyl compound can be employed, and it is not necessarily limited, but in general, it is appropriately selected from the range of −150 ° C. to + 60 ° C. be able to. The polymerization time is set based on the required degree of polymerization and is not limited, but is generally in the range of 0.2 to 50 hours.

(Polyolefin polyol cross-linked product)
Further, a polyolefin polyol obtained by crosslinking both polyolefin end diols with a polyfunctional isocyanate can also be used as the pressure-sensitive adhesive of the present invention.

  The polyolefin terminal diol preferably includes one or more polyolefin polyols selected from the group consisting of polyols having a polyolefin structure. Examples of polyols having a polyolefin structure include polyethylene both-end diol, polypropylene both-end diol, hydrogenated polybutadiene both-end diol, hydrogenated polyisoprene both-end diol, and other polyolefin polyols.

Polyolefin polyols having a number average molecular weight (Mn) of 1500 to 50000, preferably 1500 to 5000, more preferably 1500 to 4000, and most preferably 1500 to 3000 are suitable as the polyolefin both-end diol that can be used in the crosslinked product.
The polyolefin polyol preferably has a hydroxyl value (mgKOH / g) of 20 or more from the viewpoint of the strength of the release agent coating film, curability and solubility in a solvent, and from the viewpoint of influence on the peeling force, the hydroxyl value ( mgKOH / g) is preferably 75 or less. More preferably, the hydroxyl value (mgKOH / g) is 25-60.
Therefore, a hydrogenated polybutadiene both-end diol, a hydrogenated polyisoprene both-end diol, or the other polyolefin both-end diol having a hydroxyl value of 20 to 75 mgKOH / g is preferable.

Commercially available products can be used as the polyolefin both-end diol that can be used in the crosslinked product. For example, Polybd (registered trademark) R-45HT (hydroxyl-terminated liquid polybutadiene: Mn = 2800, hydroxyl value = 46.6 mg KOH / g, manufactured by Idemitsu Kosan Co., Ltd.), Poly jp (registered trademark) (hydroxyl-terminated liquid polyisoprene: Mn = 2500, hydroxyl value = 46.6 mg KOH / g, manufactured by Idemitsu Kosan Co., Ltd., Epol (registered trademark) (hydroxyl-terminated liquid hydrogenated polyisoprene: Mn = 2500, hydroxyl value = 50.5 mg KOH / g, Idemitsu Kosan Co., Ltd.) GI-1000 (hydroxyl group-containing liquid hydrogenated polybutadiene: Mn = 1500, hydroxyl value = 60 to 75 mgKOH / g, manufactured by Nippon Soda Co., Ltd.), GI-2000 (hydroxyl group-containing liquid hydrogenated polybutadiene: Mn = 2100, hydroxyl group) Value = 40-55 mg KOH / g, manufactured by Nippon Soda Co., Ltd.), GI-3000 (Hydroxyl-containing liquid hydrogenated polybutadiene: Mn = 3000, hydroxyl value = 25-35 mg KOH / g, manufactured by Nippon Soda Co., Ltd.) and the like. All of these polyols are liquid at normal temperature.

Alternatively, other polyolefin polyols that are solid at normal temperature include, for example, Unistor (registered trademark) P-801 (16% toluene solution of hydroxyl group-containing polyolefin, hydroxyl value 40 mgKOH / g, manufactured by Mitsui Chemicals, Inc.) When toluene is removed, it is solid and sticky. Alternatively, Unistor (registered trademark) P-901 (22% toluene solution of hydroxyl group-containing polyolefin, hydroxyl value 50 mgKOH / g, manufactured by Mitsui Chemicals, Inc.) can also be used.

Examples of the polyfunctional isocyanate that can be used as a cross-linking agent include polyisocyanate compounds such as hexamethylene diisocyanate, tolylene diisocyanate, diphenimemethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, or prepolymerized polyisocyanates. A modified form of isocyanate can be used.

A tackifier (tackifier) can be added to adjust the adhesive strength of the adhesive. The tackifier includes rosin resin, terpene resin, and petroleum resin, and the addition amount is 20% to 30% with respect to the main component polyolefin polyol elastomer.

The rosin resin is an ester resin derived from rosin, a natural resin, and as commercially available products, Pencel (registered trademark) A, AZ, C, D-125, D-135, D-160, etc. manufactured by Arakawa Chemical Industries, Ltd. There are ester gum AAL, A, AAV, AT, H, HP and the like.

In general, rosin-based resins are colored, while there are light-colored rosin derivatives with little coloration, and commercially available Pine Crystal (registered trademark) KE-100, KE-311, and KE-359 manufactured by Arakawa Chemical Industries, Ltd. and so on.

The terpene resin is a terpene phenol resin derived from rosin which is a natural resin, and commercially available products include terpene phenol resins Tanomaru (registered trademark) 803L and 901 manufactured by Arakawa Chemical Industries, Ltd.

The petroleum-based resin is an alicyclic saturated hydrocarbon resin, and commercially available products are Alcon (registered trademark) P-90, P-100, P-115, P-125, P-140, M-140 manufactured by Arakawa Chemical Industries, Ltd. 90, M-100, M-115, and M-135.
While tackifiers from natural products are colored, alkone is colorless and transparent, and is suitable as an additive for the adhesive of the surface protective film of optical members.

In addition to tackifier, plasticizers, fats and oils, antioxidants and the like may be added as necessary.

"Second adhesive layer"
≪Adhesive used for the second adhesive layer≫
The second adhesive layer 13 is weakly adhesive, and a coating-type weakly adhesive type adhesive can be used. For example, an acrylic adhesive, a rubber adhesive, and a urethane adhesive are appropriately used. Among them, an acrylic pressure-sensitive adhesive having stable stability and adhesiveness is preferably used. Specifically, the acrylic adhesive is an organic solvent-diluted acrylic adhesive mainly composed of a methacrylic acid alkyl ester, an acrylic acid alkyl ester polymer or a copolymer, and the rubber adhesive is a polybutylene adhesive. Examples of the coating adhesive and the urethane adhesive include coating adhesives such as polybutylene adhesive.

Homopolypropylene (density = 0.900 g / cm ³ , MFR = 5 g / 10 min, melting point = 155 ° C.) was used as the base material, and a 40 μm-thick film (haze 3%) using a single-layer T-die cast film forming machine ), And the one-sided surface of the monolayer film was subjected to corona treatment in the following examples.

(Polymer A of vinyl ether polymer)
The inside of the glass reaction vessel equipped with a three-way stopcock was purged with nitrogen, and then heated at 150 ° C. while introducing dry nitrogen gas to remove adsorbed water on the glass surface. After returning the glass reaction vessel to room temperature, a solvent and a monomer having the following composition were introduced.

Cyclohexanedimethanol monovinyl ether: 5 parts by weight 4-hydroxybutyl vinyl ether: 3.5 parts by weight Normal propyl vinyl ether: 2.5 parts by weight Cyclohexanedimethanol divinyl ether: 1 part by weight 1-isobutoxyethyl acetate: 0.04 parts by weight Ethyl acetate: 8 parts by weight Toluene: 40 parts by weight

The glass reaction vessel was cooled, and when the temperature reached 0 ° C., 1 mmol of ethylaluminum sesquichloride and 9 ml of toluene that had been cooled to 0 ° C. in advance were added dropwise to initiate polymerization.

The polymerization reaction was continued for 24 hours while maintaining a temperature of 0 ° C., and then a 0.3 wt% ammonia / methanol solution was added to the glass reaction vessel to stop the polymerization reaction.
A polymer A solution of a vinyl ether polymer having a solid content concentration of 20% was obtained.

Example 1
An ink having the following composition was prepared to obtain an adhesive B ink.

Polymer A solution of vinyl ether polymer: 100 parts by weight Hydrogenated petroleum resin “Alcon (registered trademark) P-90”: 3 parts by weight (manufactured by Arakawa Chemical Industries, Ltd.)

An ink having the following composition was prepared and diluted to a solid content concentration of 15% to obtain an adhesive C ink.

Acrylic resin “Nissetsu (registered trademark) KP-1420”: 13.3 parts by weight (manufactured by Nippon Carbide Industries Co., Ltd.)
Curing agent “CK-101”: 0.1 part by weight (manufactured by Nippon Carbide Industries Co., Ltd.)
Toluene, methyl ethyl ketone 1: 1 solvent: 74.4 parts by weight

  On the corona-treated surface of the polypropylene film, the adhesive B ink was applied by a roll coating method so as to have a dry film thickness of 2.0 μm and dried. A pressure-sensitive adhesive C ink was applied thereon with a comma coater so as to have a dry film thickness of 10 μm and dried to obtain a surface protective film of Example 1.

  The adhesive strength of the surface protective film second adhesive layer 2 of Example 1 is 0.3 N / 25 mm with respect to the acrylic mirror plate, and the adhesive strength of the first adhesive layer 1 is 0.2 N / 25 mm with respect to the acrylic mirror plate. Met.

  When the surface protective film of Example 1 was bonded to the plastic sheet 21 as the adherend, it showed an adhesive strength of 0.15 N / 25 mm with respect to the smooth surface of one side of the PET substrate, and the high surface of the opposite surface. The adhesive strength of 0.2 N / 25 mm was shown with respect to the acrylic lens shaping surface having a triangular protrusion of 30 μm.

  From the visual observation of the state of bonding, no defects such as lifting and peeling of the surface protective film were observed, the adhesive was not peeled off, and the peeling work could be easily performed. In addition, the bonding method to the plastic sheet 21 was performed using a multilaminator (Multilaminator GL835PRO manufactured by Nippon GC Corporation) under the conditions of 23 ° C., pressure 0.5 MPa, and speed 600 mm / min. The measuring method of adhesive strength was measured from the method based on JIS Z-0237.

(Example 2)
A commercially available hydrogenated polyolefin solution was used as adhesive D ink.
Unistor P-901 has a performance as a hot melt adhesive when applied and dried, and has a number average molecular weight of not less than 5000 and a hydroxyl value of 50 mgKOH / g.

22% toluene solution of hydroxyl group-containing polyolefin Unistor (registered trademark) P-901 (manufactured by Mitsui Chemicals, Inc.)

  Adhesive D ink was applied to the corona-treated surface of the polypropylene film by a gravure reverse coating method so as to have a dry film thickness of 2.0 μm and dried. The adhesive C ink was applied thereon by a gravure reverse coating method so as to have a dry film thickness of 10 μm and dried to obtain a surface protective film of Example 2.

  The adhesive strength of the surface protective film second adhesive layer 2 of Example 2 is 0.3 N / 25 mm with respect to the acrylic mirror plate, and the adhesive strength of the first adhesive layer 1 is 0.2 N / 25 mm with respect to the acrylic mirror plate. Met.

  When the surface protective film of Example 2 was bonded to the plastic sheet 21 as the adherend, it showed an adhesive strength of 0.15 N / 25 mm with respect to the smooth surface of one side of the PET substrate, and the high surface of the opposite surface. The adhesive strength of 0.2 N / 25 mm was shown with respect to the acrylic lens shaping surface having a triangular protrusion of 30 μm.

  From the visual observation of the state of bonding, no defects such as lifting and peeling of the surface protective film were observed, the adhesive was not peeled off, and the peeling work could be easily performed. In addition, the bonding method to the plastic sheet 21 was performed using a multilaminator (Multilaminator GL835PRO manufactured by Nippon GC Corporation) under the conditions of 23 ° C., pressure 0.5 MPa, and speed 600 mm / min. The measuring method of adhesive strength was measured from the method based on JIS Z-0237.

(Example 3)
An ink having the following composition was prepared to obtain an adhesive E ink.

Hydroxyl-containing polyolefin “Unistor (registered trademark) P-801”: 100 parts by weight (manufactured by Mitsui Chemicals, 16% toluene solution, hydroxyl value 40 mgKOH / g)
Hydrogenated petroleum resin “Alcon (registered trademark) P-100”: 1 part by weight (Arakawa Chemical Industries, Ltd.)

  On the corona-treated surface of the polypropylene film, the adhesive E ink was applied by a roll coating method so as to have a dry film thickness of 1.0 μm and dried. A pressure-sensitive adhesive C ink was applied thereon with a comma coater so as to have a dry film thickness of 9.0 μm and dried to obtain a surface protective film of Example 3.

  The adhesive strength of the surface protective film second adhesive layer 2 of Example 3 is 0.3 N / 25 mm with respect to the acrylic mirror plate, and the adhesive strength of the first adhesive layer 1 is 0.2 N / 25 mm with respect to the acrylic mirror plate. Met.

  When the surface protective film of Example 3 was bonded to the plastic sheet 21 as the adherend, it showed an adhesive strength of 0.15 N / 25 mm with respect to the smooth surface of the PET substrate on one side, and the high surface on the opposite side. The adhesive strength of 0.2 N / 25 mm was shown with respect to the acrylic lens shaping surface having a triangular protrusion of 30 μm.

  From the visual observation of the state of bonding, no defects such as lifting and peeling of the surface protective film were observed, the adhesive was not peeled off, and the peeling work could be easily performed. In addition, the bonding method to the plastic sheet 21 was performed using a multilaminator (Multilaminator GL835PRO manufactured by Nippon GC Corporation) under the conditions of 23 ° C., pressure 0.5 MPa, and speed 600 mm / min. The measuring method of adhesive strength was measured from the method based on JIS Z-0237.

Example 4
An ink having the following composition was prepared to obtain an adhesive F ink.

Hydroxyl-terminated liquid polyisoprene “Poly ip (registered trademark)”: 100 parts by weight (manufactured by Idemitsu Kosan Co., Ltd., Mn = 2500, hydroxyl value = 46.6 mgKOH / g)
Hydroxyl-containing liquid hydrogenated polybutadiene “GI-1000”: 100 parts by weight (manufactured by Nippon Soda Co., Ltd., Mn = 1500, hydroxyl value = 60 to 75 mgKOH / g)
Hexamethylene diisocyanate: 9 parts by weight Tolylene diisocyanate: 9 parts by weight Hydrogenated petroleum resin “Alcon (registered trademark) P-90”: 3 parts by weight (manufactured by Arakawa Chemical Industries, Ltd.)
Toluene, methyl ethyl ketone 1: 1 solvent mixture: 900 parts by weight

  On the corona-treated surface of the polypropylene film, the adhesive F ink was applied by a roll coating method so as to have a dry film thickness of 2.5 μm and dried. A pressure-sensitive adhesive C ink was applied thereon with a comma coater to a dry film thickness of 10 μm and dried to obtain a surface protective film of Example 4.

  The adhesive strength of the surface protective film second adhesive layer 2 of Example 4 is 0.3 N / 25 mm with respect to the acrylic mirror plate, and the adhesive strength of the first adhesive layer 1 is 0.2 N / 25 mm with respect to the acrylic mirror plate. Met.

  When the surface protective film of Example 4 was bonded to the plastic sheet 21 as the adherend, it exhibited an adhesive strength of 0.15 N / 25 mm with respect to the smooth surface of one side of the PET substrate, and the high surface of the opposite surface. The adhesive strength of 0.2 N / 25 mm was shown with respect to the acrylic lens shaping surface having a triangular protrusion of 30 μm.

From the visual observation of the state of bonding, no defects such as lifting and peeling of the surface protective film were observed, the adhesive was not peeled off, and the peeling work could be easily performed. In addition, the bonding method to the plastic sheet 21 was performed using a multilaminator (Multilaminator GL835PRO manufactured by Nippon GC Corporation) under the conditions of 23 ° C., pressure 0.5 MPa, and speed 600 mm / min. The measuring method of adhesive strength was measured from the method based on JIS Z-0237.

  It is possible to provide a surface protective film that does not change the force when peeling on a smooth surface or an uneven surface.

DESCRIPTION OF SYMBOLS 1: 1st adhesion layer 2: 2nd adhesion layer 2 ': 2nd adhesion layer 11: Surface protection film base material 15: Surface protection film of this invention 21: Plastic sheet of an optical member 22: Film 25: Formation on a film Optical member plastic sheet

Claims (4)

  A polypropylene film substrate, a first adhesive layer formed on the substrate, and a second adhesive layer formed on the first adhesive layer, the first adhesive layer comprising a polyolefin polyol as a main component A surface protective film characterized by comprising:   An optical member plastic sheet having a convex shape on the surface, wherein the surface protective film according to claim 1 is bonded to the convex surface, wherein the convex shape of the surface of the optical member plastic sheet is the surface protective material. An optical member plastic sheet, which passes through the second adhesive layer of the film and penetrates to the first adhesive layer.   The surface protective film according to claim 1, wherein the polyolefin polyol is a hydroxyalkyl vinyl ether polymer or a copolymer of hydroxyalkyl vinyl ether and alkyl vinyl ether.   The surface protective film according to claim 1, wherein the polyolefin polyol is a polyolefin polyol crosslinked with a urethane bond.

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