Surface protective film, optical member, and electronic member

Abstract

The invention discloses a surface protective film, an optical component and an electronic component, and belongs to the technical field of protective films, and a carbamate adhesive composition at least comprises a carbamate prepolymer and an antistatic functional agent; the antistatic functional agent is composed of an ionic compound and a surfactant, and the addition ratio of the ionic compound to the surfactant is greater than or equal to 2 and less than or equal to 50; the carbamate prepolymer is obtained through reaction of first polyol and an organic polyisocyanate compound, the first polyol comprises polyether polyol and polyester polyol, and the adding proportion of the polyether polyol to the polyester polyol meets the condition that the ratio of the polyether polyol to the polyester polyol is larger than or equal to 5 and smaller than or equal to 50. According to the invention, the problem of ionic compound precipitation is solved through the specific addition proportion of polyether polyol and polyester polyol, and mutual balance of low stripping charged voltage and low ion precipitation concentration of the surface protection film is finally realized through mutual cooperation with the specific addition proportion of the ionic compound and the surfactant.

Description

Technical Field

[0001] The present invention belongs to the technical field of protective films, and particularly relates to a surface protective film, an optical component, and an electronic component. Background Art

[0002] During the production process of optical and electronic devices, the surface protective film, as an important protective layer to prevent scratches during processing, assembly, inspection, and transportation, its peelability is particularly crucial. Especially during the assembly process of precision devices such as organic EL displays, for the consideration of improving production efficiency, rapid peeling is often required. This requires that when the protective film completes its protective mission, it must be able to achieve clean peeling between the substrate interfaces, avoiding residues or damages.

[0003] Currently, the adhesive layer of the surface protective film usually adopts a polyurethane-based adhesive layer. With its excellent reprocessing performance, surface wetting characteristics, and optical transparency, it has become the preferred material for the protective film of optical and electronic devices. To address the problem of static charge accumulation during the peeling process, the conventional method is to add ionic compounds to the adhesive to reduce the surface resistance value. However, it is found in practical applications that the electrostatic discharge performance of the polyurethane adhesive modified solely by ionic compounds shows obvious fluctuations under high-speed peeling conditions, with a relatively high and unstable peeling charged voltage.

[0004] Chinese Patent No. CN117210145A discloses an antistatic surface protective film. The antistatic surface protective film adds an antistatic functional agent to the adhesive composition. Among them, the antistatic agent is composed of an ionic compound and a surfactant, and the addition ratio of the ionic compound to the surfactant satisfies: 2 < ionic liquid / surfactant < 250. This invention enables the protective film to be rapidly peeled and reduces the peeling charged voltage by using these two different antistatic agents, namely ionic liquid and surfactant, in a specific ratio.

[0005] However, this patent still has some points for improvement: it does not consider the problem that ionic compounds will precipitate in the polyurethane-based adhesive (the precipitation is particularly serious under high temperature and high humidity conditions), and instead will corrode the protected components.

[0006] Therefore, there is an urgent need to provide a protective film to solve the above problems.

[0007] It should be noted that this part of the content of the present invention only provides the background technology related to the present invention, and does not necessarily constitute the prior art or the well-known technology. Summary of the Invention

[0008] The present invention provides a surface protective film, an optical component, and an electronic component, which at least solve the problems of high peeling voltage and precipitation of ionic compounds existing in the polyurethane-based adhesive layer of the surface protective film in the prior art.

[0009] To achieve the above object, in a first aspect, the present invention provides a surface protective film, comprising a urethane-based adhesive layer, the urethane-based adhesive layer being composed of a urethane-based adhesive, the urethane-based adhesive being formed from a urethane-based adhesive composition, the urethane-based adhesive composition at least comprising a urethane prepolymer and an antistatic functional agent; the antistatic functional agent being composed of an ionic compound and a surfactant, the addition ratio of the ionic compound to the surfactant satisfying: 2 ≤ ionic compound / surfactant ≤ 50; the urethane prepolymer being obtained by reacting a first polyol and an organic polyisocyanate compound, the first polyol including a polyether polyol and a polyester polyol, the addition ratio of the polyether polyol to the polyester polyol satisfying: 5 ≤ polyether polyol / polyester polyol ≤ 50.

[0010] Further, the addition ratio of the ionic compound to the surfactant satisfies: 2 ≤ ionic compound / surfactant ≤ 30; the addition ratio of the polyether polyol to the polyester polyol satisfies: 5 ≤ polyether polyol / polyester polyol ≤ 25.

[0011] Further, the mass ratio of the ionic compound to the polyester polyol is 1:(1 - 10).

[0012] Further, the crosslinking density of the urethane prepolymer is 76% - 80%.

[0013] Further, the molecular weight of the polyether polyol is 50,000 - 100,000, and the PDI is 5 - 10.

[0014] Further, the molecular weight of the polyester polyol is 30,000 - 80,000, and the PDI is 5 - 10.

[0015] Further, the equivalent ratio of the NCO group of the organic polyisocyanate compound to the OH group of the first polyol, calculated as NCO group / OH group, is 1.0 - 2.0.

[0016] Further, the surface energy of the urethane prepolymer is 38 mN / m - 43 mN / m.

[0017] Further, the surfactant is a fluorine-based additive, specifically selected from at least one of a fluorine-containing compound, a fluorine-based compound containing a hydroxy group, and a fluorine-based compound containing a crosslinkable functional group.

[0018] Further, the ionic compound is a composition of at least one of an onium cation and a metal cation and a fluoroorganic anion.

[0019] Further, based on the urethane-based adhesive composition being 100% by mass percentage, the content ratio of the antistatic functional agent is 0.1% or more.

[0020] Furthermore, the urethane-based adhesive composition further includes a second polyol and a polyfunctional isocyanate compound.

[0021] Furthermore, after the surface protective film is pasted on the glass, when the surface protective film is peeled off at a peeling speed of 15 m / min, the peeling charged voltage is less than 100 V.

[0022] Furthermore, after the surface protective film is pasted on the copper foil, the copper foil is tested at 20 V for 15 min, and there is no corrosion and yellowing of the copper foil.

[0023] On the other hand, the present invention also provides an optical member with the above-mentioned surface protective film attached thereto.

[0024] On the other hand, the present invention also provides an electronic member with the above-mentioned surface protective film attached thereto.

[0025] The beneficial effects of the present invention are as follows: In the present invention, by using a combination of a polyether polyol and a polyester polyol as the first polyol for preparing the urethane prepolymer, and through a specific addition ratio of the polyether polyol and the polyester polyol, the problem that ionic compounds will precipitate in the polyurethane-based adhesive is successfully solved, and it synergistically interacts with the specific addition ratios of the ionic compounds and the surfactant, and finally realizes the mutual balance between the low peeling charged voltage and the low ionic precipitation concentration of the surface protective film. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 A schematic cross-sectional view of the surface protective film according to a preferred embodiment of the present invention; Figure 2 The XPS spectrum of the surface protective film obtained in Example 1 of the present invention; Figure 3 The XPS spectrum of the surface protective film obtained in Example 9 of the present invention; Figure 4 The XPS spectrum of the surface protective film obtained in Comparative Example 4 of the present invention.

[0028] Explanation of the reference numerals: 100, surface protective film; 10, substrate layer; 20, adhesive layer. Detailed Description of the Embodiments

[0029] In the present invention, unless otherwise specified, directional words such as "upper, lower, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0033] ≪≪1. Surface protection film≫≫ The surface protection film according to the embodiment of the present invention includes a urethane-based pressure-sensitive adhesive layer. Any appropriate release liner having a releasable property may be bonded to the adhesive surface side of the urethane-based pressure-sensitive adhesive layer within a range not impairing the effects of the present invention.

[0034] The surface protection film according to the embodiment of the present invention preferably has a substrate layer and a urethane adhesive layer. The substrate layer may be one layer or more than two layers. The urethane adhesive layer may be only one layer or more than two layers. The surface protection film of the present invention may have any other appropriate layers in addition to the substrate layer and the urethane adhesive layer, within the scope of not impairing the effect of the present invention.

[0035] Figure 1It is a schematic cross-sectional view of a surface protective film according to a preferred embodiment of the present invention. The surface protective film 100 includes a substrate layer 10 and an adhesive layer 20. The surface protective film of the present invention may further have any other appropriate layers such as a release liner (not shown) as needed.

[0036] For the side of the substrate layer 10 where the adhesive layer 20 is not attached, in order to form a winding body that is easy to unwind, for example, fatty acid amide, polyethyleneimine, long-chain alkyl-based additives, etc. can be added to the substrate layer for release treatment, or a coating layer composed of any appropriate release agent such as a silicone-based, long-chain alkyl-based, fluorine-based release agent can be provided on the substrate layer.

[0037] Examples of the release liner that can be provided on the adhesive surface side of the urethane-based adhesive layer include: a release liner obtained by subjecting the surface of a substrate such as paper and a plastic film (liner substrate) to silicone treatment, and a release liner obtained by laminating a polyolefin-based resin on the surface of a substrate such as paper and a plastic film (liner substrate).

[0038] Examples of the plastic film as the substrate of the release liner include: polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

[0039] The thickness of the release liner is preferably 1 μm to 500 μm, more preferably 3 μm to 450 μm, further preferably 5 μm to 400 μm, and particularly preferably 10 μm to 300 μm.

[0040] The thickness of the surface protective film according to the embodiment of the present invention can be set to any appropriate thickness according to the use. Representatively, it is preferably 10 μm to 300 μm, more preferably 15 μm to 250 μm, further preferably 20 μm to 200 μm, and particularly preferably 25 μm to 150 μm.

[0041] ≪1-1. Urethane-based adhesive layer≫ The urethane-based adhesive layer is composed of a urethane-based adhesive. The urethane-based adhesive is formed from a urethane-based adhesive composition. That is, the adhesive layer is obtained by laminating a layer of the urethane-based adhesive formed from the urethane-based adhesive composition.

[0042] The urethane-based adhesive can be defined as an adhesive formed from a urethane-based adhesive composition. This is because, since the urethane-based adhesive composition becomes a urethane-based adhesive through a crosslinking reaction or the like caused by heating or ultraviolet irradiation, etc., it is impossible to directly specify the urethane-based adhesive by its structure, and there may be impractical situations ("impossible / impractical situations"). Therefore, according to the definition of "formed from a urethane-based adhesive composition", the urethane-based adhesive is properly specified as a "substance".

[0043] As the thickness of the urethane-based adhesive layer, it is preferably 1 μm to 150 μm, more preferably 5 μm to 150 μm, further preferably 10 μm to 150 μm, further preferably 20 μm to 150 μm, further preferably 30 μm to 150 μm, further preferably 40 μm to 150 μm, further preferably 50 μm to 150 μm, particularly preferably 60 μm to 150 μm, and most preferably 65 μm to 150 μm. If the thickness of the urethane-based adhesive layer can be increased as above, the surface protective film according to the embodiment of the present invention can well follow the unevenness when protecting a display with relatively large unevenness such as an organic EL display.

[0044] The urethane-based adhesive is formed from a urethane-based adhesive composition. As such a forming method, any appropriate forming method can be adopted within the range that does not impair the effects of the present invention. As such a forming method, for example, a method of directly applying the urethane-based adhesive composition to an arbitrary appropriate base film (for example, the base layer in the surface protective film according to the embodiment of the present invention) and drying or curing it (direct method), a method of laminating a urethane-based adhesive layer formed on the surface of a release liner (release surface) by applying the urethane-based adhesive composition thereto and drying or curing it to a base film (for example, the base layer in the surface protective film according to the embodiment of the present invention) to transfer the urethane-based adhesive layer (transfer method) can be cited. From the viewpoint of the anchoring property of the adhesive layer, the direct method can be preferably adopted representatively.

[0045] As a method of applying (representatively, coating) such a urethane-based adhesive layer, various conventionally known methods such as a roll coating method, an intaglio coating method, a reverse coating method, a slot coating method, a dip coating method, a bar coating method, a roller brush coating method, a spraying method, a doctor blade coating method, an air knife coating method, a spraying method, a comma knife coating method, a direct coating method, and a coating method using a slot die coater can be appropriately adopted.

[0046] The drying of the urethane-based adhesive composition can be carried out under heating as needed (for example, by heating to about 60°C to 150°C). As a method for curing the urethane-based adhesive composition, for example, ultraviolet rays, laser, α-rays, β-rays, γ-rays, X-rays, and electron beams can be appropriately used.

[0047] The urethane-based adhesive composition contains a urethane prepolymer, a second polyol, and a polyfunctional isocyanate compound.

[0048] The weight ratio of the total amount of the urethane prepolymer, the second polyol, and the polyfunctional isocyanate compound in the urethane-based adhesive composition is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, still more preferably 90% by weight to 100% by weight, particularly preferably 95% by weight to 100% by weight, and most preferably 98% by weight to 100% by weight. By adjusting the weight ratio of the total amount of the urethane prepolymer and the second polyol in the urethane-based adhesive composition within the above range, the surface protective film of the present invention can effectively exhibit the effects of the present invention.

[0049] The equivalent ratio of the NCO group to the OH group in the urethane prepolymer and the polyfunctional isocyanate compound is preferably 1.0 to 2.0 in terms of NCO group / OH group, more preferably 1.1 to 1.9, still more preferably 1.2 to 1.8, and particularly preferably 1.2 to 1.7. By adjusting the equivalent ratio of the NCO group / OH group within the above range, the surface protective film according to the embodiment of the present invention has more excellent wettability and more excellent unevenness followability even when adhered to an adherend with large surface unevenness, and thus a more sufficient high adhesion rate can be achieved.

[0050] The content ratio of the polyfunctional isocyanate compound in the urethane-based adhesive composition is preferably 2.5 parts by weight to 40 parts by weight, more preferably 4 parts by weight to 30 parts by weight, still more preferably 5 parts by weight to 20 parts by weight, and particularly preferably 6 parts by weight to 15 parts by weight relative to 100 parts by weight of the urethane prepolymer. By adjusting the content ratio of the polyfunctional isocyanate compound within the above range, the surface protective film according to the embodiment of the present invention has more excellent wettability and more excellent unevenness followability even when adhered to an adherend with large surface unevenness, and thus a more sufficient high adhesion rate can be achieved.

[0051] <1-1-1. Urethane prepolymer> The urethane prepolymer is typically a polyurethane polyol, preferably a substance obtained by reacting a first polyol, which specifically includes a polyester polyol (p1) and a polyether polyol (p2), with an organic polyisocyanate compound (p3) in the presence or absence of a catalyst.

[0052] The urethane prepolymer can be only one kind, or two or more kinds.

[0053] The number average molecular weight Mn of the urethane prepolymer is preferably 1000 - 100000.

[0054] As the polyester polyol (p1), within the range not impairing the effects of the present invention, any suitable polyester polyol can be used. As such a polyester polyol (p1), for example, a polyester polyol obtained by reacting an acid component and a diol component can be cited. As the acid component, for example: terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, trimellitic acid. As the diol component, for example: ethylene glycol, propylene glycol, diethylene glycol, butanediol, 1,6 - hexanediol, 3 - methyl - 1,5 - pentanediol, 3,3'-dimethylolethane, polyethylene glycol, polypropylene glycol, 1,4 - butanediol, neopentyl glycol, butylethylpentanediol; as the polyol component, glycerol, trimethylolpropane, pentaerythritol can be cited. As the polyester polyol (p1), in addition, for example, a polyester polyol obtained by ring - opening polymerization of lactones such as polycaprolactone, poly(β - methyl - γ - valerolactone), and polyvalerolactone can also be cited.

[0055] Regarding the molecular weight of the polyester polyol (p1), it can be used from low molecular weight to high molecular weight. Regarding the molecular weight of the polyester polyol (p1), the number average molecular weight is preferably 500 - 5000. If the number average molecular weight is less than 500, the reactivity may increase, leading to easy gelation. If the number average molecular weight exceeds 5000, the reactivity may decrease, and further the cohesion of the polyurethane polyol itself may become smaller.

[0056] As the polyether polyol (p2), within the range not impairing the effects of the present invention, any suitable polyether polyol can be used. As such a polyether polyol (p2), for example: a polyether polyol obtained by polymerizing an ethylene oxide compound such as water, propylene glycol, ethylene glycol, glycerol, trimethylolpropane, etc. as an initiator and ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc. As such a polyether polyol (p2), for example: polyether polyols having a functionality of 2 or more such as polypropylene glycol, polyethylene glycol, and polybutylene glycol can be cited.

[0057] The polyether polyol (p2) can have a part of it replaced with, for example, glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, pentaerythritol, or polyamines such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, and xylenediamine, and then used in combination.

[0058] As the polyether polyol (p2), a bifunctional polyether polyol can be used alone, or a polyether polyol having at least three or more hydroxyl groups in one molecule can be used partially or entirely.

[0059] As the organic polyisocyanate compound (p3), any suitable organic polyisocyanate compound can be used within the range that does not impair the effects of the present invention. Examples of such organic polyisocyanate compounds (p3) include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates.

[0060] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-toluene triisocyanate, 1,3,5-phenylene triisocyanate, benzidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4''-triphenylmethane triisocyanate.

[0061] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0062] Examples of araliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylbenzene dimethyl diisocyanate, and 1,3-tetramethylbenzene dimethyl diisocyanate.

[0063] As alicyclic polyisocyanates, examples include: 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane.

[0064] As the organic polyisocyanate compound (p3), it is possible to use in combination the trimethylolpropane adduct, the biuret formed after reaction with water, and the trimer having an isocyanurate ring.

[0065] As the catalyst that can be used when producing a urethane prepolymer (typically a polyurethane polyol), any suitable catalyst can be used within the range that does not impair the effects of the present invention. Examples of such catalysts include: tertiary amine compounds and organometallic compounds.

[0066] Examples of the tertiary amine compounds include: triethylamine, triethylenediamine, 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU).

[0067] Examples of the organometallic compounds include: tin-based compounds and non-tin-based compounds.

[0068] Examples of the tin-based compounds include: dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, tin 2-ethylhexanoate.

[0069] Examples of the non-tin-based compounds include: titanium-based compounds such as dibutyltitanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead-based compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron-based compounds such as iron 2-ethylhexanoate and iron acetoacetate; cobalt-based compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc-based compounds such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium-based compounds such as zirconium naphthenate.

[0070] When a catalyst is used in the production of urethane prepolymers (typically polyurethane polyols), in a system containing two types of polyols, namely polyester polyol (p1) and polyether polyol (p2), due to the difference in their reactivity, if a single catalyst system is used, problems such as gelation or turbidity of the reaction solution are likely to occur. Therefore, by using two catalysts in the production of urethane prepolymers (typically polyurethane polyols), it is easy to control the reaction rate, catalyst selectivity, etc., and these problems can be solved. Examples of such a combination of two catalysts include, for example: tertiary amine / metal organic system, tin-based / non-tin-based, tin-based / tin-based, preferably tin-based / tin-based, and more preferably a combination of dibutyltin dilaurate and tin 2-ethylhexanoate. As the mixing ratio, in terms of weight ratio, tin 2-ethylhexanoate / dibutyltin dilaurate is preferably less than 1, and more preferably 0.2 - 0.6. If the mixing ratio is 1 or more, gelation may easily occur due to the balance of catalyst activities.

[0071] When a catalyst is used in the production of urethane prepolymers (typically polyurethane polyols), the amount of the catalyst used is preferably 0.01 wt% - 1.0 wt% relative to the total amount of the polyester polyol (p1), polyether polyol (p2), and organic polyisocyanate compound (p3).

[0072] When a catalyst is used in the production of urethane prepolymers (typically polyurethane polyols), the reaction temperature is preferably below 100 °C, and more preferably 85 °C - 95 °C. If it reaches 100 °C or higher, it may be difficult to control the reaction rate and crosslinked structure, and thus it may be difficult to obtain a urethane prepolymer (typically polyurethane polyol) with a specified molecular weight.

[0073] When producing urethane prepolymers (typically polyurethane polyols), a catalyst can also be used. In this case, the reaction temperature is preferably 100 °C or higher, and more preferably 110 °C or higher. In addition, when obtaining a urethane prepolymer (typically polyurethane polyol) without a catalyst, it is preferably reacted for 3 hours or more.

[0074] Examples of methods for producing urethane prepolymers (typically polyurethane polyols) include: 1) a method of adding all of the polyester polyol (p1), polyether polyol (p2), catalyst, and organic polyisocyanate compound (p3) to a flask; 2) a method of adding the polyester polyol (p1), polyether polyol (p2), and catalyst to a flask and then dropwise adding the organic polyisocyanate compound (p3). As a method for producing urethane prepolymers (typically polyurethane polyols), in terms of controlling the reaction, the method of 2) is preferred.

[0075] When manufacturing urethane prepolymers (representatively polyurethane polyols), any suitable solvent can be used within the range that does not impair the effects of the present invention. Examples of such solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Among these solvents, ethyl acetate is preferred.

[0076] <1-1-2. Second polyol> Examples of the second polyol include polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols. As the second polyol, polyester polyols and polyether polyols are more preferred.

[0077] As the polyester polyol, for example, it can be obtained by the esterification reaction of a polyol component and an acid component.

[0078] Examples of the polyol component include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecane diol, glycerol, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol.

[0079] Examples of the acid component include succinic acid, methyl succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and their acid anhydrides.

[0080] Examples of the polyether polyol include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using water, low molecular weight polyols (such as propylene glycol, ethylene glycol, glycerol, trimethylolpropane, pentaerythritol, etc.), bisphenols (such as bisphenol A, etc.), and dihydroxybenzenes (such as catechol, resorcinol, hydroquinone, etc.) as initiators. Specifically, examples include polyethylene glycol, polypropylene glycol, and polybutylene glycol.

[0081] Examples of the polycaprolactone polyol include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

[0082] Examples of the polycarbonate polyol include: a polycarbonate polyol obtained by polycondensing the above polyol component with phosgene; a polycarbonate polyol obtained by transesterification condensation of the above polyol component with a dicarbonate such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethyl butyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, or dibenzyl carbonate; a copolycarbonate polyol obtained by using two or more of the above polyol components; a polycarbonate polyol obtained by esterifying the above various polycarbonate polyols with a carboxyl group-containing compound; a polycarbonate polyol obtained by etherifying the above various polycarbonate polyols with a hydroxyl group-containing compound; a polycarbonate polyol obtained by transesterifying the above various polycarbonate polyols with an ester compound; a polycarbonate polyol obtained by transesterifying the above various polycarbonate polyols with a hydroxyl group-containing compound; a polyester-based polycarbonate polyol obtained by polycondensing the above various polycarbonate polyols with a dicarboxylic acid compound; a copolyether-based polycarbonate polyol obtained by copolymerizing the above various polycarbonate polyols with an alkylene oxide.

[0083] Examples of the castor oil-based polyol include: a castor oil-based polyol obtained by reacting castor oil fatty acid with the above polyol component. Specifically, examples include a castor oil-based polyol obtained by reacting castor oil fatty acid with polypropylene glycol.

[0084] The second polyol contains a polyol (A1) having a number average molecular weight Mn of 5000 to 20000 and a polyol (A2) having a number average molecular weight Mn of 300 to 4999. By making the second polyol contain a polyol (A1) having a number average molecular weight Mn of 5000 to 20000 and a polyol (A2) having a number average molecular weight Mn of 300 to 4999, the effects of the present invention can be more significantly exhibited.

[0085] The polyol (A1) may be only one kind or two or more kinds.

[0086] The polyol (A2) may be only one kind or two or more kinds.

[0087] In terms of being able to more significantly exhibit the effects of the present invention, the content ratio of the total amount of the polyol (A1) and the polyol (A2) in the second polyol is preferably 80% by weight to 100% by weight, more preferably 90% by weight to 100% by weight, further preferably 95% by weight to 100% by weight, particularly preferably 98% by weight to 100% by weight, and most preferably substantially 100% by weight.

[0088] The number-average molecular weight Mn of the polyol (A1) is from 5000 to 20000, preferably from 6000 to 18000, more preferably from 7000 to 16000, still more preferably from 8000 to 15000, and particularly preferably from 9000 to 14000. If the number-average molecular weight Mn of the polyol (A1) is within the above range, the effects of the present invention can be more prominently shown.

[0089] The number-average molecular weight Mn of the polyol (A2) is from 300 to 4999, preferably from 350 to 4500, more preferably from 400 to 4000, still more preferably from 500 to 3800, and particularly preferably from 700 to 3500. If the number-average molecular weight Mn of the polyol (A2) is within the above range, the effects of the present invention can be more prominently shown.

[0090] The weight ratio of the polyol (A1) to the polyol (A2) is preferably 1.0 ≤ (A1 / A2) ≤ 3.5, more preferably 1.0 ≤ (A1 / A2) ≤ 3.0, still more preferably 1.0 ≤ (A1 / A2) ≤ 2.5, and particularly preferably 1.0 ≤ (A1 / A2) ≤ 2.0. If the weight ratio of the polyol (A1) to the polyol (A2) is within the above range, the effects of the present invention can be more prominently shown.

[0091] As the polyol (A1), in terms of being able to more prominently show the effects of the present invention, the number of OH groups it has is preferably from 3 to 6, more preferably from 3 to 5, still more preferably from 3 to 4, and particularly preferably 3.

[0092] As the polyol (A1), in terms of being able to more prominently show the effects of the present invention, the triol having 3 OH groups preferably contains 50% to 100% by weight, more preferably 70% to 100% by weight, still more preferably 90% to 100% by weight, particularly preferably 95% to 100% by weight, and most preferably substantially 100% by weight.

[0093] As the polyol (A2), in terms of being able to more prominently show the effects of the present invention, the number of OH groups it has is preferably from 3 to 6, more preferably from 3 to 5, still more preferably from 3 to 4, and particularly preferably 3.

[0094] As the polyol (A2), in terms of being able to more prominently show the effects of the present invention, the triol having 3 OH groups preferably contains 50% to 100% by weight, more preferably 70% to 100% by weight, still more preferably 90% to 100% by weight, particularly preferably 95% to 100% by weight, and most preferably substantially 100% by weight.

[0095] <1-1-3. Polyfunctional Isocyanate Compounds> The polyfunctional isocyanate compound may be only one kind, or two or more kinds.

[0096] As the polyfunctional isocyanate compound, any suitable polyfunctional isocyanate compound that can be used in the carbamate esterification reaction can be used. Examples of such polyfunctional isocyanate compounds include: polyfunctional aliphatic isocyanate compounds, polyfunctional alicyclic isocyanates, and polyfunctional aromatic isocyanate compounds.

[0097] Examples of the polyfunctional aliphatic isocyanate compound include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate.

[0098] Examples of the polyfunctional alicyclic isocyanate compound include: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated tetramethylbenzene dimethyl diisocyanate.

[0099] Examples of the polyfunctional aromatic diisocyanate compound include: phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate.

[0100] As the polyfunctional isocyanate compound B, addition products of trimethylolpropane with various polyfunctional isocyanate compounds as described above, biuret bodies obtained by reaction with water, and trimers having an isocyanurate ring can also be cited. In addition, the above substances can be used in combination.

[0101] <1-1-4. Other Components> In addition to the urethane prepolymer, the second polyol, and the polyfunctional isocyanate compound, within the scope not impairing the effects of the present invention, the urethane-based adhesive composition may further contain any other appropriate components. Examples of such other components include: resin components other than the urethane prepolymer and the second polyol, crosslinking agents other than the polyfunctional isocyanate compound, crosslinking retardants, ionic compounds, fluorine-based additives, silicone-based additives, fatty acid esters, tackifiers, inorganic fillers, organic fillers, metal powders, pigments, foils, softeners, anti-aging agents, conductive agents, ultraviolet absorbers, antioxidants, light stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants, solvents, and catalysts.

[0102] 〔Ionic compound〕 If an ionic compound is included as another component, the antistatic performance of the surface protective film according to the embodiment of the present invention can be improved.

[0103] As the content ratio of the ionic compound, any appropriate content ratio can be adopted within the scope not impairing the effects of the present invention. In terms of being able to further improve the antistatic performance of the surface protective film of the present invention, the content ratio of the ionic compound relative to the total amount of the urethane prepolymer and the second polyol is preferably 0.05% by weight or more, more preferably 0.10% to 50% by weight, further preferably 0.20% to 30% by weight, particularly preferably 0.30% to 10% by weight, and most preferably 0.50% to 3% by weight. If the content ratio of the ionic compound relative to the total amount of the urethane prepolymer and the second polyol is within the above range, the antistatic performance of the surface protective film of the present invention can be further improved. If the content ratio of the ionic compound relative to the total amount of the urethane prepolymer and the second polyol is less than the above range, sufficient antistatic performance may not be imparted to the surface protective film of the present invention. If the content ratio of the ionic compound relative to the total amount of the urethane prepolymer and the second polyol is greater than the above range, contamination of the adherend may increase.

[0104] As the ionic compound, any appropriate ionic compound can be adopted within the scope not impairing the effects of the present invention. The ionic compound can be only one kind, or two or more kinds.

[0105] As the ionic compound, in terms of being able to more prominently exhibit the effects of the present invention, an ionic compound containing at least one selected from onium cations and metal cations and a fluoro-organic anion, and an organosilicon oligomer containing an ionic group are preferred. In terms of being able to make the appearance of the adhesive layer more excellent, an ionic compound containing at least one selected from onium cations and metal cations and a fluoro-organic anion is more preferred.

[0106] The ionic compound can be an ionic liquid. An ionic liquid refers to a molten salt (ionic compound) that is in a liquid state at 25°C.

[0107] As the ionic group-containing organosilicon oligomer, any suitable ionic group-containing organosilicon oligomer can be used within the scope not impairing the effects of the present invention. Examples of the ionic group-containing organosilicon oligomer include, for example, D product name “X-40-2450” manufactured by Shin-Etsu Chemical Co., Ltd.

[0108] As the onium cation, any suitable onium cation can be used within the scope not impairing the effects of the present invention. In terms of being able to more prominently show the effects of the present invention, as such an onium cation, it is preferably at least one selected from an ammonium cation (nitrogen-containing onium cation), a sulfonium cation (sulfur-containing onium cation), and a phosphorus-containing onium cation (phosphonium cation), and more preferably an ammonium cation.

[0109] As the metal cation, any suitable metal cation can be used within the scope not impairing the effects of the present invention. In terms of being able to more prominently show the effects of the present invention, as such a metal cation, it is preferably an alkali metal cation such as a Li cation, a Na cation, or a K cation.

[0110] As the fluoroorganic anion, any suitable fluoroorganic anion can be used within the scope not impairing the effects of the present invention. The fluoroorganic anion can be fully fluorinated (perfluorinated) or partially fluorinated.

[0111] Examples of such fluoroorganic anions include, for example: fluorinated aryl sulfonates, perfluoroalkane sulfonates, bis(fluorosulfonyl)imide, bis(perfluoroalkanesulfonyl)imide, cyano perfluoroalkanesulfonyl amide, bis(cyano)perfluoroalkanesulfonyl methylide, cyano-bis(perfluoroalkanesulfonyl)methylide, tris(perfluoroalkanesulfonyl)methylide, trifluoroacetate, perfluoroalkane compounds, tris(perfluoroalkanesulfonyl)methylide, (perfluoroalkanesulfonyl)trifluoroacetamide, etc.

[0112] Among these fluoroorganic anions, in terms of being able to more prominently show the effects of the present invention, perfluoroalkyl sulfonates, bis(fluorosulfonyl)imide, and bis(perfluoroalkanesulfonyl)imide are preferred; more specifically, for example, trifluoromethane sulfonate, pentafluoroethane sulfonate, heptafluoropropane sulfonate, nonafluorobutane sulfonate, bis(fluorosulfonyl)imide, bis(trifluoromethanesulfonyl)imide; bis(fluorosulfonyl)imide and bis(trifluoromethanesulfonyl)imide are preferred.

[0113] As the ionic compound, in terms of being able to more prominently show the effects of the present invention, an ionic compound composed of an onium cation and a fluoroorganic anion is more preferred.

[0114] As an onium cation, it is preferably at least one having a structure represented by any one of general formulas (1) to (4).

[0115]

Chemical Formula 1

[0116] In general formula (2), Rd represents a hydrocarbon group having 2 to 20 carbon atoms, which may contain a heteroatom, and Re, Rf, and Rg are the same or different and represent hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, which may contain a heteroatom.

[0117] In general formula (3), Rh represents a hydrocarbon group having 2 to 20 carbon atoms, which may contain a heteroatom, and Ri, Rj, and Rk are the same or different and represent hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, which may contain a heteroatom.

[0118] In general formula (4), Z represents a nitrogen atom, a sulfur atom, or a phosphorus atom, and Rl, Rm, Rn, and Ro are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms, which may contain a heteroatom. Among them, when Z is a sulfur atom, there is no Ro.

[0119] Examples of the cation structure represented by general formula (1) include a pyridinium cation structure, a pyrrolidinium cation structure, a piperidinium cation structure, a cation structure having a pyrroline skeleton, a cation structure having a pyrrole skeleton, and the like.

[0120] As specific examples of the cation represented by the general formula (1), for example, pyridinium cations such as 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-ethyl-3-methylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation; pyrrolidinium cations such as 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidinium cation, 1-methyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium cation, 1-ethyl-1-propylpyrrolidinium cation, 1-ethyl-1-butylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation, 1-ethyl-1-heptylpyrrolidinium cation, 1,1-dipropylpyrrolidinium cation, 1-propyl-1-butylpyrrolidinium cation, 1,1-dibutylpyrrolidinium cation; piperidinium cations such as 1-propylpiperidinium cation, 1-pentylpiperidinium cation, 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-methyl-1-pentylpiperidinium cation, 1-methyl-1-hexylpiperidinium cation, 1-methyl-1-heptylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1-ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1-propyl-1-butylpiperidinium cation, 1,1-dimethylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1,1-dibutylpiperidinium cation; 2-methyl-1-pyrroline cation; 1-ethyl-2-phenylindole cation; 1,2-dimethylindole cation; 1-ethylcarbazole cation; and these cations further have a cation having at least one selected from vinyl (CH2=CH-group) and allyl (CH2=CH-CH2-group).

[0121] Among them, in terms of further showing the effects of the present invention, preferably, examples include: pyridinium cations such as 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-ethyl-3-methylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-octyl-4-methylpyridinium cation; pyrrolidinium cations such as 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidinium cation, 1-methyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium cation, 1-ethyl-1-propylpyrrolidinium cation, 1-ethyl-1-butylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation, 1-ethyl-1-heptylpyrrolidinium cation; piperidinium cations such as 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-methyl-1-pentylpiperidinium cation, 1-methyl-1-hexylpiperidinium cation, 1-methyl-1-heptylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1-ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1-propyl-1-butylpiperidinium cation; cations such as these cations further having at least one of vinyl (CH2=CH-group) and allyl (CH2=CH-CH2-group), more preferably 1-hexylpyridinium cation, 1-ethyl-3-methylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, 1-methyl-1-propylpyrrolidinium cation, 1-methyl-1-propylpiperidinium cation, and these cations further having at least one selected from vinyl (CH2=CH-group) and allyl (CH2=CH-CH2-group).

[0122] As the cation structure represented by the general formula (2), examples include: imidazolium cation structure, tetrahydropyridinium cation structure, dihydropyridinium cation structure, etc.

[0123] Specific examples of the cation represented by the general formula (2) include, for example: 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3-dimethylimidazolium cation and other imidazolium cations; 1,3-dimethyl-1,4,5,6-tetrahydropyridinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyridinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyridinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyridinium cation and other tetrahydropyridinium cations; 1,3-dimethyl-1,4-dihydropyridinium cation, 1,3-dimethyl-1,6-dihydropyridinium cation, 1,2,3-trimethyl-1,4-dihydropyridinium cation, 1,2,3-trimethyl-1,6-dihydropyridinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyridinium cation, 1,2,3,4-tetramethyl-1,6-dihydropyridinium cation and other dihydropyridinium cations; and these cations further having at least one cation selected from vinyl (CH2=CH- group) and allyl (CH2=CH-CH2- group).

[0124] Among them, in terms of being able to further exhibit the effects of the present invention, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, and these cations further having at least one cation selected from vinyl (CH2=CH- group) and allyl (CH2=CH-CH2- group) are preferred, and 1-ethyl-3-methylimidazolium cation and 1-hexyl-3-methylimidazolium cation, and these cations further having at least one cation selected from vinyl (CH2=CH- group) and allyl (CH2=CH-CH2- group) are more preferred.

[0125] Specific examples of the cation structure represented by the general formula (3) include, for example: pyrazolium cation structure, pyrazolinium cation structure, etc.

[0126] Specific examples of the cation represented by the general formula (3) include, for example: pyrazolium cations such as 1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation, 1-ethyl-2,3,5-trimethylpyrazolium cation, 1-propyl-2,3,5-trimethylpyrazolium cation, 1-butyl-2,3,5-trimethylpyrazolium cation; pyrazolinium cations such as 1-ethyl-2,3,5-trimethylpyrazolinium cation, 1-propyl-2,3,5-trimethylpyrazolinium cation, 1-butyl-2,3,5-trimethylpyrazolinium cation; and cations having at least one selected from vinyl (CH2=CH- group) and allyl (CH2=CH-CH2- group).

[0127] Specific examples of the cation structure represented by the general formula (4) include, for example: tetraalkylammonium cation structure, trialkylsulfonium cation structure, tetraalkylphosphonium cation structure, and structures in which a part of the above alkyl groups is replaced by alkenyl, alkoxy or epoxy groups.

[0128] As specific examples of the cation represented by the general formula (4), for example, tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, trimethylpropylammonium cation, trimethyldecylammonium cation, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N,N-dimethyl-N-ethyl-N-propylammonium cation, N,N-dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl-N-ethyl-N-hexylammonium cation, N,N-dimethyl-N-ethyl-N-heptylammonium cation, N,N-dimethyl-N-ethyl-N-nonylammonium cation, N,N-dimethyl-N,N-dipropylammonium cation, N,N-diethyl-N-propyl-N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl-N-hexylammonium cation, N,N-dimethyl-N-propyl-N-heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-diethyl-N-butyl-N-heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexylammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N-propylammonium cation, N,N-diethyl-N-methyl-N-pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N,N-dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N,N-dipropyl-N,N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, N-methyl-N-ethyl-N-propyl-N-pentylammonium cation and other tetraalkylammonium cations; trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation and other trialkylsulfonium cations; tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrahexylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation and other tetraalkylphosphonium cations; and cations having at least one selected from vinyl (CH2=CH-group) and allyl (CH2=CH-CH2-group).

[0129] As an ionic compound, an ionic compound containing at least one selected from the above-mentioned onium cations and the above-mentioned metal cations and the above-mentioned fluoroorganic anions, and an ionic group-containing organosilicon oligomer are preferred. More preferably, an ionic compound containing at least one selected from the above-mentioned onium cations and the above-mentioned metal cations and the above-mentioned fluoroorganic anions is used. Further preferably, an ionic compound containing the above-mentioned onium cation and the above-mentioned fluoroorganic anion is used.

[0130] In terms of being able to more prominently show the effects of the present invention, as ionic compounds, specifically, 1-hexylpyridinium bis(fluorosulfonyl)imide, 1-ethyl-3-methylpyridinium trifluoromethanesulfonate, 1-ethyl-3-methylpyridinium pentafluoroethanesulfonate, 1-ethyl-3-methylpyridinium heptafluoropropanesulfonate, 1-ethyl-3-methylpyridinium nonafluorobutanesulfonate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium heptafluoropropanesulfonate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-hexyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-allyl-3-methyl-imidazolium trifluoromethanesulfonate, 1-allyl-3-methyl-imidazolium heptafluoropropanesulfonate, 1-allyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, 1-allyl-3-methyl-imidazolium bis(fluorosulfonyl)imide, methyltrioctylammonium bis(trifluoromethanesulfonyl)imide, trimethylpropylammonium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide are preferred; more preferably, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-allyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, methyltrioctylammonium bis(trifluoromethanesulfonyl)imide, trimethylpropylammonium bis(trifluoromethanesulfonyl)imide are preferred; particularly preferably, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-allyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, methyltrioctylammonium bis(trifluoromethanesulfonyl)imide, trimethylpropylammonium bis(trifluoromethanesulfonyl)imide.

[0131] The ionic compounds can be commercially available compounds or compounds synthesized by any suitable method. For example, ionic liquids can be synthesized by methods such as the halide method, the hydroxide method, the acid ester method, the complex method, and the neutralization method.

[0132] [Surfactant] If a fluorine-based additive as a surfactant is included as other components, the easy peelability and antistatic performance of the surface protective film according to the embodiment of the present invention can be further improved.

[0133] As the fluorine-based additive, any suitable fluorine-based additive can be used within the range that does not impair the effects of the present invention.

[0134] The fluorine-based additive can be only one kind or two or more kinds.

[0135] The content ratio of the fluorine-based additive relative to the total amount of the urethane prepolymer and the second polyol is preferably 0.01% by weight or more, more preferably 0.03 parts by weight to 30 parts by weight, further preferably 0.05 parts by weight to 10 parts by weight, and particularly preferably 0.05 parts by weight to 1 part by weight. If the content ratio of the fluorine-based additive relative to the total amount of the urethane prepolymer and the second polyol is within the above range, the easy peelability and antistatic performance of the surface protective film according to the embodiment of the present invention can be further improved.

[0136] In terms of being able to more prominently exhibit the effects of the present invention, the total content of the fluorine-based additive and the silicone-based additive described later relative to the total amount of the urethane prepolymer and the second polyol is 0.01% by weight or more, more preferably 0.03 parts by weight to 30 parts by weight, further preferably 0.05 parts by weight to 10 parts by weight, and particularly preferably 0.05 parts by weight to 1 part by weight.

[0137] Examples of the fluorine-based additive include at least one selected from fluorine-containing compounds, fluorine-containing compounds with a hydroxyl group, and fluorine-containing compounds with a crosslinkable functional group.

[0138] Examples of the fluorine-containing compound include compounds having a fluorinated aliphatic hydrocarbon skeleton, fluorinated organic compounds obtained by copolymerizing an organic compound and a fluorine-based compound, and fluorine-containing compounds containing an organic compound. Examples of the fluorinated aliphatic hydrocarbon skeleton include fluoromethane, fluoroethane, fluoropropane, fluoroisopropane, fluorobutane, fluoroisobutane, fluorotert-butane, fluoropentane, fluorohexane, and other fluorinated C1-C10 alkanes. Herein, the notation "C1-C10" indicates that the number of carbon atoms is 1 to 10.

[0139] A preferred embodiment of the fluorine-containing compound is an oligomer having a fluorine-containing group and a hydrophilic group and / or a lipophilic group (“specific fluorine-based compound”). By using such a “specific fluorine-based compound”, the easy peelability and antistatic performance of the surface protective film according to the embodiment of the present invention can be improved. In particular, by using such a “specific fluorine-based compound” in combination with an ionic compound, the easy peelability and antistatic performance of the surface protective film according to the embodiment of the present invention can be further improved. It is speculated that this is because the specific fluorine-based compound makes the ionic compound uneven on the surface side (the side in contact with the adherend) of the urethane-based adhesive layer. As the fluorine-containing group, typically, a fluoroalkyl group (e.g., CF3−, etc.) and / or a fluoroalkylene group (e.g., -CF2-CF2−, etc.) can be cited. The hydrophilic group refers to a group having hydrophilicity. The hydrophilicity is translated as “hydrophilic” and means the property of having an affinity for water, which is a property generally understood by those skilled in the art. The lipophilic group refers to a group having lipophilicity. The lipophilicity is translated as “lipophilic” and means the property of having an affinity for oil, which is a property generally understood by those skilled in the art.

[0140] As the fluorine-containing compound, from the viewpoint of further improving the easy peelability of the surface protective film according to the embodiment of the present invention, the surface tension when prepared as a 0.1% toluene solution is preferably 19.0 mN / m to 26.0 mN / m (the surface tension of toluene is 27.9 mN / m). In this way, if the surface tension of the fluorine-containing compound when prepared as a 0.1% toluene solution is within the narrow specific range of 19.0 mN / m to 26.0 mN / m, the easy peelability of the surface protective film according to the embodiment of the present invention can be further improved.

[0141] As the fluorine-containing compound, from the viewpoint of further improving the antistatic performance of the surface protective film according to the embodiment of the present invention, the surface tension when prepared as a 0.1% toluene solution is preferably 26.0 mN / m to 28.0 mN / m (the surface tension of toluene is 27.9 mN / m). In this way, if the surface tension of the fluorine-containing compound when prepared as a 0.1% toluene solution is within the narrow specific range of 26.0 mN / m to 28.0 mN / m, the antistatic performance of the surface protective film according to the embodiment of the present invention can be further improved.

[0142] As the fluorine-containing compound, in terms of commercially available products, for example, the following substances can be cited.

[0143] DMAGAFACE series manufactured by DIC Corporation: Typically, "MAGAFACEF-114", "MAGAFACEF-251", "MAGAFACEF-253", "MAGAFACEF-281", "MAGAFACEF-410", "MAGAFACEF-430", "MAGAFACEF-444", "MAGAFACEF-477", "MAGAFACEF-510", "MAGAFACEF-551-A", "MAGAFACEF-553", "MAGAFACEF-554", "MAGAFACEF-555-A", "MAGAFACEF-556", "MAGAFACEF-557", "MAGAFACEF-558", "MAGAFACEF-559", "MAGAFACEF-560", "MAGAFACEF-561", "MAGAFACEF-562", "MAGAFACEF-563", "MAGAFACEF-565", "MAGAFACEF-568", "MAGAFACEF-569", "MAGAFACEF-570", "MAGAFACEF-576", "MAGAFACER-01", "MAGAFACER-40", "MAGAFACER-40-LM", "MAGAFACER-41", "MAGAFACER-41-LM", "MAGAFACER-94", "MAGAFACERS-56", "MAGAFACERS-72-K", "MAGAFACERS-75-A", "MAGAFACERS-75-NS", "MAGAFACERS-78", "MAGAFACERS-90", etc.

[0144] DSURFLON series manufactured by AGC SEIMI CHEMICAL Co., Ltd.: Typically, "S-242", "S-243", "S-386", etc.

[0145] DFC series manufactured by Sumitomo 3M Co., Ltd.: Typically, "FC-4430", "FC-4432", etc.

[0146] DFTERGENT series manufactured by NEOS Co., Ltd.: Typically, "FTERGENT100", "FTERGENT100C", "FTERGENT110", "FTERGENT150", "FTERGENT150CH", "FTERGENT250", "FTERGENT400SW", etc.

[0147] DPF series manufactured by Kitamura Chemical Industry Co., Ltd.: Typically, “PF-136A”, “PF-156A”, “PF-151N”, “PF-636”, “PF-6320”, “PF-656”, “PF-6520”, “PF-651”, “PF-652”, “PF-3320” and the like.

[0148] As the hydroxy group-containing fluorine compound, for example, known resins can be used. Examples include hydroxy group-containing fluorine resins described in International Publication No. 94 / 06870 Pamphlet, Japanese Patent Laid-Open No. 8-12921, Japanese Patent Laid-Open No. 10-72569, Japanese Patent Laid-Open No. 4-275379, International Publication No. 97 / 11130 Pamphlet, International Publication No. 96 / 26254 Pamphlet and the like. As other hydroxy group-containing fluorine resins, examples include fluorine-olefin copolymers described in Japanese Patent Laid-Open No. 8-231919, Japanese Patent Laid-Open No. 10-265731, Japanese Patent Laid-Open No. 10-204374, Japanese Patent Laid-Open No. 8-12922 and the like. In addition, copolymers of compounds having a fluorinated alkyl group in the hydroxy group-containing compound, fluorinated organic compounds copolymerized from a hydroxy group-containing compound and a fluorine-containing compound, fluorine-containing compounds containing a hydroxy group-containing organic compound and the like can be cited. As such hydroxy group-containing fluorine compounds, commercially available products include, for example, the trade name “LUMIFLON” (manufactured by Asahi Glass Co., Ltd.), the trade name “CEFRALCOAT” (manufactured by Central Glass Co., Ltd.), the trade name “ZAFLON” (manufactured by Toagosei Co., Ltd.), the trade name “ZEFFLE” (manufactured by Daikin Industries, Ltd.) and the like.

[0149] As the crosslinkable functional group-containing fluorine compound, examples include carboxylic acid compounds having a fluorinated alkyl group such as perfluorooctanoic acid, copolymers of compounds having a fluorinated alkyl group in the crosslinkable functional group-containing compound, fluorinated organic compounds copolymerized from a crosslinkable functional group-containing compound and a fluorine-containing compound, fluorine-containing compounds containing a crosslinkable functional group-containing compound and the like. As such crosslinkable functional group-containing fluorine compounds, commercially available products include, for example, the trade names “MEGAFAC F-570”, “MEGAFAC RS-55”, “MEGAFAC RS-56”, “MEGAFAC RS-72-K”, “MEGAFAC RS-75”, “MEGAFAC RS-76-E”, “MEGAFAC RS-76-NS”, “MEGAFAC RS-78”, “MEGAFAC RS-90” (manufactured by DIC Corporation) and the like.

[0150] In terms of being able to more prominently show the effects of the present invention, the total content of the aforementioned fluorine-based additives is 0.01% by weight or more, more preferably 0.03% by weight to 30 parts by weight, further preferably 0.05% by weight to 10 parts by weight, and particularly preferably 0.05% by weight to 1% by weight, relative to the total content of the urethane prepolymer and the second polyol.

[0151] 〔Antioxidant〕 From the aspect of suppressing the deterioration of the urethane-based adhesive layer, etc., the urethane-based adhesive composition may further contain an antioxidant as other components. The antioxidant may be only one kind or two or more kinds.

[0152] As the content ratio of the antioxidant in the urethane-based adhesive composition, any appropriate content ratio can be adopted within the range that does not impair the effects of the present invention. Taking the content ratio of the antioxidant relative to the total content of the urethane prepolymer and the second polyol, such a content ratio is preferably 0.01% by weight to 10% by weight or more, more preferably 0.05% by weight to 5% by weight, further preferably 0.1% by weight to 3% by weight, and particularly preferably 0.2% by weight to 1% by weight.

[0153] Examples of the antioxidant include, for example: free radical chain inhibitors, peroxide decomposing agents, etc.

[0154] Examples of the free radical chain inhibitor include, for example: phenolic antioxidants, amine-based antioxidants, etc.

[0155] Examples of the peroxide decomposing agent include, for example: sulfur-based antioxidants, phosphorus-based antioxidants.

[0156] Examples of the phenolic antioxidant include, for example: monophenolic antioxidants, bisphenolic antioxidants, polymer-type phenolic antioxidants.

[0157] Examples of the monophenolic antioxidant include, for example: 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0158] Examples of the bisphenolic antioxidant include, for example: 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane.

[0159] As polymer phenolic antioxidants, examples include: 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetra-[methylene-3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate]methane, bis[3,3’-bis(4’-hydroxy-3’-tert-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3’,5’-di-tert-butyl-4’-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, tocopherol.

[0160] As sulfur antioxidants, examples include: dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate.

[0161] As phosphorus antioxidants, examples include: triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite.

[0162] Ultraviolet absorber From the aspect of suppressing the deterioration of the urethane-based adhesive layer, etc., the urethane-based adhesive composition may further contain an ultraviolet absorber as other components. The ultraviolet absorber may be only one kind, or two or more kinds.

[0163] As the content ratio of the ultraviolet absorber in the urethane-based adhesive composition, any appropriate content ratio can be adopted within the range that does not impair the effects of the present invention. Taking the content ratio of the ultraviolet absorber relative to the total amount of the urethane prepolymer and the second polyol, such a content ratio is preferably 0.01% by weight to 10% by weight or more, more preferably 0.05% by weight to 5% by weight, further preferably 0.1% by weight to 3% by weight, and particularly preferably 0.2% by weight to 1% by weight.

[0164] As ultraviolet absorbers, examples include: benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, oxanilide-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, triazine-based ultraviolet absorbers.

[0165] As benzophenone-based ultraviolet absorbers, examples include: 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2’-dihydroxy-4-dimethoxybenzophenone, 2,2’-dihydroxy-4,4’-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane.

[0166] Examples of benzotriazole-based ultraviolet absorbers include, for example: 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-[2'-hydroxy-3'-(3'',4'',5'',6''-tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], [2(2'-hydroxy-5'-methacryloyloxyphenyl)-2H-benzotriazole.

[0167] Examples of salicylic acid-based ultraviolet absorbers include, for example: phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate.

[0168] Examples of cyanoacrylate-based ultraviolet absorbers include, for example: 2-ethylhexyl 2-cyano-3,3'-diphenylacrylate, ethyl 2-cyano-3,3'-diphenylacrylate.

[0169] [Light stabilizer] From the aspect of suppressing the deterioration of the urethane-based adhesive layer, etc., the urethane-based adhesive composition may further contain a light stabilizer as other components. The light stabilizer may be only one kind, or two or more kinds.

[0170] As the content ratio of the light stabilizer in the urethane-based adhesive composition, any appropriate content ratio can be adopted within the range that does not impair the effects of the present invention. Based on the content ratio of the light stabilizer relative to the total amount of the urethane prepolymer and the second polyol, such a content ratio is preferably 0.01% by weight to 10% by weight or more, more preferably 0.05% by weight to 5% by weight, further preferably 0.1% by weight to 3% by weight, and particularly preferably 0.2% by weight to 1% by weight.

[0171] Examples of light stabilizers include, for example: hindered amine-based light stabilizers, ultraviolet stabilizers.

[0172] Examples of hindered amine-based light stabilizers include, for example: [bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate], bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate.

[0173] Examples of the ultraviolet stabilizer include, for example, bis(octylphenyl) nickel sulfide, [2,2'-thiobis(4-tert-octylphenol)]-n-butylamine nickel, 3,5-ditert-butyl-4-hydroxybenzyl phosphoric acid monoethyl ester nickel complex, nickel dibutyldithiocarbamate, a quencher of the benzoate type, and nickel dibutyldithiocarbamate.

[0174] Fatty acid ester From the viewpoint of improving the wettability of the urethane-based adhesive layer and the like, the urethane-based adhesive composition may further contain a fatty acid ester as another component. The fatty acid ester may be only one kind or two or more kinds.

[0175] The number average molecular weight Mn of the fatty acid ester is preferably from 200 to 400, more preferably from 210 to 395, still more preferably from 230 to 380, particularly preferably from 240 to 360, and most preferably from 250 to 350. By adjusting the number average molecular weight Mn of the fatty acid ester within the above range, the wetting rate can be further improved. If the number average molecular weight Mn of the fatty acid ester is too small, the wetting rate may not be improved even if the addition amount is large. If the number average molecular weight Mn of the fatty acid ester is too large, the curability of the adhesive during drying deteriorates, which may have an adverse effect not only on the wetting properties but also on other adhesive properties.

[0176] As the fatty acid ester, any suitable fatty acid ester can be used within the range that does not impair the effects of the present invention. Examples of such fatty acid esters include, for example, polyoxyethylene bisphenol A laurate, butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, monoglyceryl behenate, cetyl 2-ethylhexanoate, isopropyl myristate, isopropyl palmitate, cholesterol isostearate, lauryl methacrylate, methyl coconut fatty acid, methyl laurate, methyl oleate, methyl stearate, myristyl myristate, octyldodecyl myristate, pentaerythritol monooleate, pentaerythritol monostearate, pentaerythritol tetrapalmitate, stearyl stearate, isotridecyl stearate, triglycerol 2-ethylhexanoate, butyl laurate, and octyl oleate.

[0177] ≪1-2. Substrate layer≫ As the thickness of the substrate layer, any suitable thickness can be adopted according to the use. The thickness of the substrate layer is preferably from 5 μm to 300 μm, more preferably from 10 μm to 250 μm, still more preferably from 15 μm to 200 μm, and particularly preferably from 20 μm to 150 μm.

[0178] The substrate layer may be a single layer or a laminate of two or more layers. The substrate layer may be stretched.

[0179] As the material of the base material layer, any suitable material can be adopted according to the use. Examples include plastics, paper, metal films, non-woven fabrics, etc. Plastics are preferred. The base material layer can be composed of only one material or two or more materials. For example, it can be composed of two or more plastics.

[0180] Examples of the above plastics include polyester resins, polyamide resins, and polyolefin resins. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include homopolymers of olefin monomers and copolymers of olefin monomers. Specifically, examples of polyolefin resins include homopolypropylene; block, random, and graft polypropylene copolymers with ethylene as a copolymer component; reactor TPO; ethylene polymers such as low-density, high-density, linear low-density, and ultra-low-density; and ethylene copolymers such as ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methacrylic acid copolymer, and ethylene-methyl methacrylate copolymer.

[0181] The base material layer can contain any suitable additives as needed. Examples of the additives that can be contained in the base material layer include antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, fillers, and pigments. The type, 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, in order to prevent deterioration, etc., it is preferred to contain a variety of the above additives. From the viewpoint of improving weather resistance, etc., as additives, particularly preferably, antioxidants, ultraviolet absorbers, light stabilizers, and fillers can be cited.

[0182] As the antioxidant, any suitable antioxidant can be adopted. Examples of such antioxidants include phenolic antioxidants, phosphorus-based processing heat stabilizers, lactone-based processing heat stabilizers, sulfur-based heat stabilizers, and phenol-phosphorus-based antioxidants. The content ratio of the antioxidant relative to the base resin of the base material layer (in the case where the base material layer is a blend, the blend is the base resin) is preferably 1% by weight or less, more preferably 0.5% by weight or less, and further preferably 0.01% by weight to 0.2% by weight.

[0183] As the ultraviolet absorber, any suitable ultraviolet absorber can be used. Examples of such ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, etc. The content ratio of the ultraviolet absorber is preferably 2% by weight or less, more preferably 1% by weight or less, and further preferably 0.01% to 0.5% by weight based on the base resin forming the base material layer (in the case where the base material layer is a blend, the blend is the base resin).

[0184] As the light stabilizer, any suitable light stabilizer can be used. Examples of such light stabilizers include hindered amine-based light stabilizers, benzoate-based light stabilizers, etc. The content ratio of the light stabilizer is preferably 2% by weight or less, more preferably 1% by weight or less, and further preferably 0.01% to 0.5% by weight based on the base resin forming the base material layer (in the case where the base material layer is a blend, the blend is the base resin).

[0185] As the filler, any suitable filler can be used. Examples of such fillers include inorganic fillers, etc. Specifically, examples of inorganic fillers include carbon black, titanium oxide, zinc oxide, etc. The content ratio of the filler is preferably 20% by weight or less, more preferably 10% by weight or less, and further preferably 0.01% to 10% by weight based on the base resin forming the base material layer (in the case where the base material layer is a blend, the blend is the base resin).

[0186] In addition, as additives, in order to impart antistatic properties, surfactants, inorganic salts, polyhydric alcohols, metal compounds, carbon, etc., which are inorganic, low molecular weight, and high molecular weight antistatic agents, are also preferably listed. In particular, from the viewpoints of pollution and maintaining adhesiveness, high molecular weight antistatic agents and carbon are preferred.

[0187] ≪≪2. Manufacturing method of the surface protective film≫≫ The surface protective film of the present invention can be manufactured by any suitable method. As such a manufacturing method, for example, it can be carried out according to any suitable manufacturing method, such as: (1) A method of coating a solution or a hot melt of the forming material of the adhesive layer on the base material layer; (2) Accordingly, a method of transferring the coated and formed diaphragm-shaped adhesive layer onto the base material layer; (3) A method of extruding the forming material of the adhesive layer onto the base material layer to form and coat; (4) A method of extruding the base material layer and the adhesive layer into a double layer or multiple layers; (5) A method of laminating the adhesive layer on the base material layer alone, or a method of double laminating the adhesive layer together with the laminated layer; (6)A method of forming a material by a double-layer or multi-layer laminate adhesive layer and a substrate layer such as a film or a laminate layer.

[0188] As a coating method, for example, a roll coater method, a comma coater method, a slot die coater method, a reverse coater method, a screen printing method, an intaglio coater method, etc. can be used.

[0189] ≪≪3. Use of the surface protective film≫≫ The surface protective film according to an embodiment of the present invention can be used for any suitable purpose. Preferably, the surface protective film of the present invention causes very little contamination of the adherend. Preferably, it has excellent wettability and reprocessability, and thus is preferably used for surface protection of, for example, optical components and electronic components.

[0190] Components pasted with the surface protective film according to an embodiment of the present invention, such as optical components and electronic components, can repeatedly attach and peel the pasted surface protective film by manual operation.

[0191] That is, the optical component according to an embodiment of the present invention is pasted with the surface protective film of the present invention. In addition, the electronic component according to an embodiment of the present invention is pasted with the surface protective film of the present invention.

[0192] The present invention provides a surface protective film, including a urethane-based adhesive layer, the urethane-based adhesive layer is composed of a urethane-based adhesive, the urethane-based adhesive is formed by a urethane-based adhesive composition, the urethane-based adhesive composition at least includes a urethane prepolymer and an antistatic functional agent; the antistatic functional agent is composed of an ionic compound and a surfactant, and the addition ratio of the ionic compound to the surfactant satisfies: 2 ≤ ionic compound / surfactant ≤ 50; the urethane prepolymer is obtained by reacting a first polyol and an organic polyisocyanate compound, the first polyol includes a polyether polyol and a polyester polyol, and the addition ratio of the polyether polyol to the polyester polyol satisfies: 5 ≤ polyether polyol / polyester polyol ≤ 50.

[0193] The ionic compound added in the present application achieves charge dissipation by reducing the surface resistance, while the surfactant can inhibit the aggregation of the ionic compound and improve the dispersion uniformity. The synergistic effect of the two can stabilize the charge release during the peeling process and reduce the sudden change of the static voltage caused by charge accumulation. In the prior art, a pure polyether polyol is generally used to prepare the urethane prepolymer. However, compared with the polyester polyol (-COO-) adhesive, the polyether polyol (-C-O-C-) adhesive has a lower polarity, weaker intermolecular force and is usually a non-crystalline material, and has poor compatibility with the ionic compound with low polarity or non-polarity, resulting in the easy migration of the ionic compound in the material. The present invention reduces the precipitation of the ionic compound by reasonably compounding the polyether polyol and the polyester polyol while ensuring the properties of the adhesive itself.

[0194] Furthermore, the addition ratio of the ionic compound to the surfactant satisfies: 2 ≤ ionic compound / surfactant ≤ 30; the addition ratio of the polyether polyol to the polyester polyol satisfies: 5 ≤ polyether polyol / polyester polyol ≤ 25.

[0195] It can be understood that the reasonable compounding of the ionic compound and the surfactant can ensure the balance between the charge dissipation efficiency and the dispersibility. The reasonable compounding of the polyether polyol and the polyester polyol optimizes the balance between the peel electrification voltage and the ionic stability.

[0196] It can be understood that the limitation of the ratio range of the ionic compound and the surfactant in this application, as well as the limitation of the ratio range of the polyether polyol and the polyester polyol, can also be understood as the component compounding ratio range of the antistatic functional agent and the component compounding ratio range of the first polyol. In fact, the prior art usually does not consider the addition ratio of the polyether polyol and the polyester polyol. The prior art usually uses a pure polyether system, or simply mixes the polyether polyol and the polyester polyol in a one-to-one ratio, without considering the technical effect that adding the polyester polyol can reduce the precipitation of the ionic compound in the adhesive.

[0197] Furthermore, the addition ratio of the polyether polyol and the polyester polyol and the addition ratio of the ionic compound and the surfactant in this application actually have a synergistic effect within a certain specific range. The content of the polyester polyol does not have a simple linear relationship with the precipitation of the anti-ionic compound. When the amount of the polyester polyol is too small, the polymer network is not dense enough, so the ionic compound is prone to precipitation. However, after the polyester polyol reaches a certain specific limit, even if it exceeds this limit, the precipitation concentration of the ionic compound will no longer decrease, indicating that the crosslinking density of the polymer network under this limit is sufficient to control the precipitation of the ionic compound. However, when the amount of the polyester polyol is too large, the polymer network is too dense, which will instead affect the property of the ionic compound itself to reduce the peel electrification voltage. Therefore, this application reasonably sets the addition ratio of the polyether polyol and the polyester polyol and the addition ratio of the ionic compound and the surfactant, and finally realizes the balance between the low peel electrification voltage and the low ionic precipitation concentration of the surface protective film.

[0198] Furthermore, the mass ratio of the ionic compound to the polyester polyol is 1:(1 - 10). In the present application, the mass ratio of the ionic compound to the polyester polyol is reasonably set, which can effectively balance the ability to reduce the peel charging voltage and resist ion precipitation. With respect to the mass of the ionic compound, when the polyester polyol is excessive, the polymer network is too dense, resulting in difficulty for ions to move and neutralize the static charges at the peel interface, instead leading to an increase in the peel charging voltage. At the same time, when the polyester content is too high, the flexibility of the adhesive decreases, and the stress concentration during the peeling process intensifies, further increasing the peel charging voltage. When the polyester polyol is too little, the ionic compound is excessive beyond the matrix bearing capacity and easily migrates to the surface from the polymer network, resulting in a decrease in the anti-precipitation ability during long-term use, and then polluting the contact interface and causing corrosion of the adhered object.

[0199] Furthermore, the crosslinking density of the urethane prepolymer is 76% - 80%. In the present application, the ratio of the polyether polyol to the polyester polyol is reasonably set, and then the crosslinking density of the urethane prepolymer can be controlled. The pure polyether polyol has an ether bond (-O-) as the main chain structure, and the crosslinking environment has an ether bond (-O-) as the main chain structure. The free volume that can move is about 7% - 10%, and the crosslinking density only depends on the crosslinking of urethane bonds, with less physical crosslinking and a relatively low crosslinking density (about 74%), which is beneficial for the diffusion of small molecules. In the polyether / polyester mixed system, the polyester chain has an ester group (-COO-) as the main chain structure. As the proportion of the polyester system added increases, the rigid chains gradually increase, resulting in a decrease in the free volume that can move to 3 - 6%. Compared with the pure polyether system, in the polyether / polyester mixed system, the ester group can form a hydrogen bond network with the urethane, thereby enhancing physical crosslinking, effectively increasing the crosslinking density, and reducing the precipitation of ionic compounds.

[0200] Furthermore, the molecular weight of the polyether polyol is 50,000 - 100,000, and the PDI is 5 - 10. Furthermore, the molecular weight of the polyester polyol is 30,000 - 80,000, and the PDI is 5 - 10. Polymer dispersity index (PDI) is the polymer dispersity index, which is used to describe the molecular weight distribution of the polymer. In the present application, the molecular weights of the polyether polyol and the polyester polyol and the PDI are reasonably controlled, and then the lengths and distributions of the polyether chain and the polyester chain are adjusted, and the overall content and distribution uniformity of the ether bond and the ester group are controlled, so as to optimize the crosslinking structure, free volume, and ion migration path of the material, and finally achieve better antistatic performance and anti-precipitation ability.

[0201] It is understandable that pure polyether polyol has an ether bond (-O-) as the main chain structure. The dipole moment of the ether bond is 1.3D, with relatively low polarity. The polarity difference between the inside and the surface of the adhesive is small, and it is easy to form a uniform but low-polarity cross-linking environment. The polyether / polyester mixed polyester chain contains an ester group (-COO-) as the main chain structure. The dipole moment of the ester group is 1.7D, with higher polarity. Due to the influence of polarity, the ester group tends to accumulate on the surface of the adhesive. The polarity of the adhesive surface is higher than that of the inside, thereby forming a polarity gradient. A denser and more stable high-polarity region is formed on the adhesive surface, which helps to effectively reduce the precipitation of ionic compounds.

[0202] Furthermore, the equivalent ratio of the NCO group of the organic polyisocyanate compound to the OH group of the first polyol is 1.0 to 2.0 in terms of NCO group / OH group. The ester group and the ether bond form a polarity gradient. In this application, the ratio of the NCO group and the OH group is reasonably set, so that the ester groups enriched on the surface have sufficient NCO groups to participate in cross-linking, and a dense interfacial layer is formed after curing, thereby effectively reducing the precipitation of ionic compounds.

[0203] Furthermore, the surface energy of the urethane prepolymer is 38 mN / m to 43 mN / m. Pure polyether polyol has an ether bond (-O-) as the main chain structure, and the surface energy of the prepolymer is about 30 mN / m. In this application, polyester polyol is added to the system. The addition of the polar group ester group increases the surface energy of the prepolymer to 38 mN / m to 43 mN / m, enhances the intermolecular force, effectively increases the cross-linking density, and thereby reduces the precipitation of ionic compounds.

[0204] Furthermore, the surfactant is a fluorine-based additive, specifically selected from at least one of fluorine-containing compounds, fluorine-containing compounds with hydroxyl groups, and fluorine-containing compounds with cross-linkable functional groups. When the surfactant is a fluorine-containing compound, the low surface energy of the fluorine-containing compound can effectively reduce the migration of the surfactant and extend the antistatic life. More preferably, when the surfactant is a fluorine-containing compound with hydroxyl groups or a fluorine-containing compound with cross-linkable functional groups, the groups of the surfactant can react and cross-link with the polyester, which can increase the cross-linking density and further limit ion migration.

[0205] Furthermore, the ionic compound is a composition of at least one of onium cations and metal cations and fluoro-organic anions. When the ionic compound is a metal cation, the lone pair electrons of the ester group can accept protons and can combine with the metal cation to form a weak coordination interaction. More preferably, when the ionic compound is an onium cation, the carbonyl oxygen (C=O) in the ester group (-COO-) of the polyester polyol has strong electronegativity and can generate electrostatic attraction with the onium cation and combine through dipole-charge interaction. The ether bond (-O-) of the polyether polyol has relatively weak polarity (dipole moment about 1.3D), and the proportion of non-polar methylene (-CH2-) in its molecular chain segment is relatively high, forming a hydrophobic micro-region, which is the same as the perfluoroalkyl chain of the fluoroanion (such as CF3(CF2)3- 1) Achieve efficient binding of non-polar regions through hydrophobic interaction (van der Waals force). The low surface tension property of fluoride anions can reduce the interfacial energy of polyether polyols and promote the enrichment of fluoride anions in hydrophobic microdomains.

[0206] Furthermore, based on the urethane-based adhesive composition being 100% by mass percentage, the content ratio of the antistatic functional agent is 0.1% or more.

[0207] Furthermore, the urethane-based adhesive composition further includes a second polyol and a polyfunctional isocyanate compound.

[0208] Furthermore, when the surface protective film is pasted on the glass and peeled off at a peeling speed of 15 m / min, the peeling charged voltage is less than 100 V.

[0209] Furthermore, when the surface protective film is pasted on the copper foil and the copper foil is tested at 20 V for 15 min, there is no corrosion and yellowing of the copper foil. The surface protective film disclosed in this application has the advantage of low ion precipitation and can effectively prevent the object to be pasted from being corroded by the precipitated ionic compounds. The relevant principles will be specifically introduced below: In the polyurethane system containing ionic compounds, the corrosion of metals mainly involves electrochemical oxidation and anion complexation. Here, Cu is used as an example.

[0210] (1) Basic steps of electrochemical corrosion: Anodic reaction (copper dissolution): Cu → Cu 2+ + 2e − ; Cathodic reaction (oxygen reduction or hydrogen evolution): O2 + 2H2O + 4e − → 4OH − (neutral / alkaline environment) or 2H + + 2e − → H2 (acidic environment); The above are the reasons for the corrosion of copper under normal circumstances.

[0211] (2) Catalytic effect of ionic compound anions: CF3SO3 in the ionic compound - can form a soluble complex with Cu 2+ and further accelerate anodic dissolution. The specific reaction is as follows: Cu 2+ + 2CF3SO3 - → Cu(CF3SO3)2 (soluble). This reaction will reduce the local Cu 2+ concentration, promote the continuous progress of the anodic reaction, and accelerate anodic dissolution.

[0212] (3) Oxide layer destruction and prevention of repassivation: The initial oxide layer on the copper surface is Cu2O or CuO, and the specific reactions are as follows: 4Cu + O2 → 2Cu2O (cuprous oxide); However, the anions of ionic compounds will weaken the oxide layer structure through adsorption and hinder repassivation. The specific reactions are as follows: Cu2O + 4CF3SO3 - + H2O → 2Cu(CF3SO3)2 + 2OH − .

[0213] In summary, it can be seen that when no measures are taken to prevent the precipitation of ionic compounds from the surface protective film, especially when the adherend is a metal, the surface protective film cannot play a protective role, but will cause the metal to be corroded.

[0214] The following will explain in detail the principle of the polyether polyol and polyester polyol mixed system in inhibiting the corrosion of metals by ionic compounds: (1) Polar binding effect of the polyester system: The polyester system can effectively inhibit the migration of ionic compounds. The ester groups (-COO-) of the polyester chain and the sulfonyl groups (-SO2-) of the ionic compounds reduce the diffusion coefficient (D) of the ionic compounds through dipole-dipole interactions, reducing surface enrichment.

[0215] (2) Complex formation competition: The ester groups can form stable complexes (such as Cu-OOCR) with Cu 2+ , reducing the formation of Cu(CF3SO3)2 and inhibiting anodic dissolution. The specific reactions are as follows: Cu 2+ + 2RCOO − → Cu(OOCR)2.

[0216] (3) Water and oxygen barrier of the crosslinked network: The low crosslinking density of the pure polyether system allows the free diffusion of water and oxygen, providing sufficient reactants for electrochemical corrosion. The high crosslinking density and hydrogen bond network formed by the polyether polyol and polyester polyol system of the present application can reduce the water molecule permeability, reduce the supply of water and oxygen required for the cathodic reaction, and inhibit the overall corrosion rate.

[0217] In summary, the pure polyether system provides a higher ability for the free diffusion of water and oxygen than the polyester system, supplying sufficient media for electrochemical reactions. The ester groups can form stable complexes with Cu 2+ , and the high crosslinking and hydrogen bonds can effectively block and reduce the electrochemical reactants. Therefore, adding polyester to the pure polyether system with ionic compounds will result in more excellent electrochemical properties.

[0218] The following will specifically explain the curing differences between the pure polyether system and the polyether / polyester combined system: The curing reactions of both polyurethane systems are based on the addition polymerization of polyols (polyethers or polyesters) and isocyanates (TDI). However, the ester groups (-COO-) in the polyester chain introduce additional polar groups, significantly affecting the crosslinked network, as shown below: (1) Curing reaction of pure polyether polyurethane: The reaction of polyether triol (PPG) with TDI generates urethane bonds: PPG-(OH)3 + 3TDI → PPG-(O-C(=O)-NH-TDI)3 + 3H2O (main reaction); Characteristics: It only relies on the chemical crosslinking of urethane bonds, with less physical crosslinking (such as hydrogen bonds) and a lower crosslinking density.

[0219] (2) Curing reaction of polyether / polyester hybrid polyurethane: When polyester polyol (PBA) reacts with TDI, the ester groups participate in the formation of hydrogen bonds: PBA-(OH) n + nTDI → PBA-(O-C(=O)-NH-TDI) n + nH2O (main reaction); Characteristics: The ester groups (-COO-) form hydrogen bonds with the N-H in the urethane: -COO−···H-N- (urethane). It can be seen that after adding polyester, in addition to chemical crosslinking, there is also physical crosslinking (such as hydrogen bonds) in the system, effectively increasing the crosslinking density.

[0220] It can be understood that in the main chain of the polyurethane molecules in the pure polyether system, in addition to urethane groups, there are also ether bond groups. Due to the presence of a large number of ether bond groups, hydrogen bonds can be formed within and between polyurethane molecules. The soft segments and hard segments are induced to form hard segment and soft segment microdomains and generate a microphase separation structure due to thermodynamic incompatibility, but the degree of microphase separation is not high. And in this application, polyester polyol is also added, which increases the degree of microphase separation between the soft segments (polyether / polyester) and the hard segments (urethane). The hard segments form dense microdomains through hydrogen bonds and van der Waals forces as physical crosslinking points, thereby effectively enhancing the physical crosslinking of the polymer.

[0221] On the other hand, the present invention also provides an optical member with the above surface protection film attached to its surface. The surface protection film can specifically include, but is not limited to, an encapsulation layer of an organic light-emitting diode (OLED), a protective layer or an optical film of a display, an optical film with a surface uneven structure (such as a diffusion film, a brightness enhancement film, etc.), components in an optical laminate (such as a polarizer, a retardation film, etc.), and a protective film for a thin optical element.

[0222] On the other hand, the present invention also provides an electronic component with the above surface protection film attached thereto. The electronic component may include, but is not limited to, an overcurrent protection element, a circuit board assembly, an organic light-emitting electronic device, an electronic device module, a consumer electronic component, and a semiconductor device.

[0223] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by any of these examples. The surface protection films in each of the examples and comparative examples were prepared according to the ratios listed in Table 1.

[0224] Table 1

[0225] It should be noted that when "parts" are described, it means "parts by weight" unless otherwise specified, and when "% " is described, it means "weight % " unless otherwise specified.

[0226] 〔Production Example〕: Production of polyurethane-based prepolymer solution 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol, and 10 parts by mass of adipic acid-methylpentanediol were charged into a polymerization experimental apparatus equipped with a 1 L round-bottom separable flask, a separable lid, a separatory funnel, a thermometer, a nitrogen inlet tube, a Liebig condenser, a vacuum seal ring, a stir bar, and a stirring blade. While stirring, 0.01 part by mass of dibutyltin (IV) dilaurate as a catalyst was charged, and nitrogen substitution was carried out at room temperature for 1 hour. Then, under nitrogen introduction, 5 parts by mass of hexamethylene diisocyanate was charged while stirring, and the temperature of the solution in the experimental apparatus was controlled to reach 90 ± 2 °C in a water bath and maintained for 4 hours to obtain a polyurethane-based prepolymer solution. It should be noted that during the polymerization, ethyl acetate was appropriately added dropwise in order to control the temperature during the polymerization process and prevent the decrease in stirrability due to an increase in viscosity. The solid content concentration of the polyurethane-based prepolymer solution was 50% by weight.

[0227] Among them, the molecular weights of polybutylene glycol and polypropylene glycol were 80,000, and the PDI was 7; the molecular weight of adipic acid-methylpentanediol was 50,000, and the PDI was 7; the equivalent ratio of the NCO group of hexamethylene diisocyanate to the OH group of polybutylene glycol and polypropylene glycol was 1.5 in terms of NCO group / OH group.

[0228] 〔Example 1〕: The polyurethane-based prepolymer of Example 1 was prepared with reference to the preparation method of the production example.

[0229] In such a way that the total solid content reaches 50% by weight, 50 parts by weight of a polyurethane prepolymer, 50 parts by weight of a polyol having three hydroxyl groups as a polyol, 10 parts by weight of an isocyanate compound as a crosslinking agent, 1.5 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound, 0.3 parts by weight of a fluorine-based oligomer MEGAFAC EDF-477 (manufactured by DIC Corporation), and 0.03 parts by weight of ferric tris(acetylacetonate) as a catalyst are diluted with ethyl acetate to obtain a urethane-based adhesive solution. Then, the urethane-based adhesive solution is coated on a substrate composed of a polyester resin (trade name "T100-75S", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation), and after drying, the thickness is 75 μm, and it is cured and dried under the conditions of a drying temperature of 130 °C and a drying time of 3 minutes to produce an adhesive layer composed of an adhesive composition. Then, the silicone-treated surface of a 25-μm-thick release sheet composed of a polyester resin (trade name "MRF25", thickness 25 μm, manufactured by Mitsubishi Chemical Corporation) with silicone treatment applied on one side is adhered to the surface of the obtained adhesive layer to obtain a surface protective film. It is aged at room temperature for 5 days and evaluated.

[0230] 〔Example 2〕: The polyurethane prepolymer of Example 2 was prepared with reference to the preparation method of the production example.

[0231] The preparation method of the surface protective film of Example 2 was referred to that of Example 1, except that 1.5 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound and 0.75 parts by weight of a fluorine-based oligomer MEGAFAC EDF-477 (manufactured by DIC Corporation) were used.

[0232] 〔Example 3〕: The polyurethane prepolymer of Example 3 was prepared with reference to the preparation method of the production example.

[0233] The preparation method of the surface protective film of Example 3 was referred to that of Example 1, except that 1.5 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound and 0.1 parts by weight of a fluorine-based oligomer MEGAFAC EDF-477 (manufactured by DIC Corporation) were used.

[0234] 〔Example 4〕: The polyurethane prepolymer of Example 4 was prepared with reference to the preparation method of the production example.

[0235] The preparation method of the surface protective film of Example 4 is referred to that of Example 1, except that 1.5 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound and 0.05 parts by weight of a fluorine-based oligomer MEGAFACED F-477 (manufactured by DIC Corporation) are used.

[0236] 〔Example 5〕: The polyurethane prepolymer of Example 5 is prepared with reference to the preparation method of the production example.

[0237] The preparation method of the surface protective film of Example 5 is referred to that of Example 1, except that 3 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound and 0.06 parts by weight of a fluorine-based oligomer MEGAFACED F-477 (manufactured by DIC Corporation) are used.

[0238] 〔Example 6〕: The polyurethane prepolymer of Example 6 is prepared with reference to the preparation method of the production example, except that 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol, and 20 parts by mass of adipic acid-methylpentanediol are used.

[0239] The preparation method of the surface protective film of Example 6 is referred to that of Example 1.

[0240] 〔Example 7〕: The polyurethane prepolymer of Example 7 is prepared with reference to the preparation method of the production example, except that 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol, and 6.7 parts by mass of adipic acid-methylpentanediol are used.

[0241] The preparation method of the surface protective film of Example 7 is referred to that of Example 1.

[0242] 〔Example 8〕: The polyurethane prepolymer of Example 8 is prepared with reference to the preparation method of the production example, except that 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol, and 4 parts by mass of adipic acid-methylpentanediol are used.

[0243] The preparation method of the surface protective film of Example 8 is referred to that of Example 1.

[0244] 〔Example 9〕: The polyurethane prepolymer of Example 9 is prepared with reference to the preparation method of the production example, except that 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol, and 2 parts by mass of adipic acid-methylpentanediol are used.

[0245] The preparation method of the surface protective film of Example 9 is referred to that of Example 1.

[0246] 〔Example 10〕: The polyurethane prepolymer of Example 10 was prepared according to the preparation method of the reference Production Example, except that the molecular weights of polybutylene glycol and polypropylene glycol were 50,000 and the PDI was 10.

[0247] For the preparation method of the surface protective film of Example 10, refer to Example 1.

[0248] 〔Example 11〕: The polyurethane prepolymer of Example 11 was prepared according to the preparation method of the reference Production Example, except that the molecular weight of the polyester polyol was 30,000 and the PDI was 10.

[0249] For the preparation method of the surface protective film of Example 11, refer to Example 1.

[0250] 〔Comparative Example 1〕: The polyurethane prepolymer of Comparative Example 1 was prepared according to the preparation method of the reference Production Example.

[0251] For the preparation method of the surface protective film of Comparative Example 1, refer to Example 1, except that 0.3 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound and 0.3 parts by weight of a fluorine-based oligomer MEGAFACED F-477 (manufactured by DIC Corporation) were used.

[0252] 〔Comparative Example 2〕: The polyurethane prepolymer of Comparative Example 2 was prepared according to the preparation method of the reference Production Example.

[0253] For the preparation method of the surface protective film of Comparative Example 2, refer to Example 1, except that 1.5 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic compound and 0.015 parts by weight of a fluorine-based oligomer MEGAFACED F-477 (manufactured by DIC Corporation) were used.

[0254] 〔Comparative Example 3〕: The polyurethane prepolymer of Comparative Example 3 was prepared according to the preparation method of the reference Production Example, except that 40 parts by mass of polybutylene glycol, 10 parts by mass of polypropylene glycol and 50 parts by mass of adipic acid-methylpentanediol were used.

[0255] For the preparation method of the surface protective film of Comparative Example 3, refer to Example 1.

[0256] 〔Comparative Example 4〕: The polyurethane prepolymer of Comparative Example 4 was prepared according to the preparation method of the reference Production Example, except that 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol and 1 part by mass of adipic acid-methylpentanediol were used.

[0257] For the preparation method of the surface protective film of Comparative Example 4, refer to Example 1.

[0258] 〔Comparative Example 5〕: The polyurethane prepolymer of Comparative Example 5 was prepared with reference to the preparation method of the production example, except that 80 parts by mass of polybutylene glycol, 20 parts by mass of polypropylene glycol and 0 part by mass of adipic acid-methylpentanediol were used.

[0259] For the preparation method of the surface protective film of Comparative Example 5, refer to Example 1.

[0260] Test Example To verify the performance of the products of the present invention, the surface protective films prepared in the examples and comparative examples were respectively subjected to relevant performance tests. The specific method is as follows. For the specific test results, refer to Table 2: <Test Method and Evaluation> Under the condition that a 2 kg roller was reciprocated once, the surface protective film with the adhesive layer exposed was attached to the surface of the glass through the adhesive layer. After standing for 30 minutes, it was used as a sample for measuring the peeling charged voltage.

[0261] <Peeling Charged Voltage> Using a tensile testing machine, the above-obtained measurement sample was peeled off at a high-speed peeling speed (15 m / min) in the 180° direction. Using a high-precision electrostatic sensor SK-035, SK-200 (manufactured by Keyence Corporation), the voltage (charged voltage) generated by the electrification of the glass was measured, and the maximum value of the measured value was used as the peeling charged voltage.

[0262] <Color Change Test> A copper sheet with a thickness of 36 μm (length and width: 50 mm × 50 mm) was designated as A; a copper foil with a thickness of 36 μm (length and width: 120 mm × 120 mm) was designated as C. The surface protective film was laminated (thickness, length and width: 75 μm × 100 mm × 100 mm) and designated as B. B was placed between A / C. The copper foils of A / C were connected to the positive and negative electrodes, and the voltage was output at 20 V or 30 V. After 15 minutes, it was checked whether the copper foil changed color.

[0263] <Crosslinking Density> Within 10 minutes after the production of the protective film is completed, peel the release liner from the protective film, scrape about 0.1 g from the adhesive layer as Sample 1. After wrapping the above Sample 1 with a PTFE filter membrane with a diameter accuracy of 0.2 μm, tie it with a kite string, and use it as Sample 2. Measure the weight of Sample 2 before the following tests, and use it as Weight A. It should be noted that the above Weight A is the total weight of Sample 1 (adhesive layer), PTFE membrane, and kite string. In addition, use the total weight of the above PTFE membrane and kite string as Weight B. Next, put the above Sample 2 into a 50 ml container filled with ethyl acetate and leave it standing at 23 °C for 1 week. Then, take out Sample 2 from the container, dry it in a dryer at 130 °C for 2 hours to remove ethyl acetate, and then measure the weight of Sample 2. Measure the weight of Sample 2 after the above tests, and use it as Weight C. Calculate the crosslink density according to the following formula.

[0264] Crosslink density (%) = [(C - B) / (A - B)] * 100%.

[0265] <Surface energy of the urethane prepolymer> By measuring the contact angle formed by the liquid (diiodomethane) on the surface of the prepolymer and combining the Young-Laplace equation and the Owens-Wendt formula, calculate the surface energy.

[0266] Table 2

[0267] From the above results, it can be seen that in the present invention, by using a combination of polyether polyol and polyester polyol for the first polyol in the production of the urethane prepolymer, and through a specific addition ratio of polyether polyol and polyester polyol, the problem that ionic compounds will precipitate in the polyurethane-based adhesive is successfully solved, and it synergistically interacts with the specific addition ratio of ionic compounds and surfactants, ultimately achieving a balance between the low peeling charged voltage and the low ionic precipitation concentration of the surface protective film.

[0268] Furthermore, as Figures 2 to 4 shown, Figure 2 is the XPS spectrum of the surface protective film obtained in Example 1, Figure 3 is the XPS spectrum of the surface protective film obtained in Example 9, Figure 4 is the XPS spectrum of the surface protective film obtained in Comparative Example 4. The present application further verifies through the XPS spectrum that adding a specific proportion of polyester polyol in the present application improves the surface polarity, increases the polarity gradient, thereby increasing the crosslink density, restricting the migration ability of small molecules, and significantly reducing the precipitation of fluorine.

[0269] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combinations of each technical feature in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A surface protection film, characterized in that: The surface protection film includes a urethane adhesive layer, the urethane adhesive layer is composed of a urethane adhesive, the urethane adhesive is formed of a urethane adhesive composition, and the urethane adhesive composition includes at least a urethane prepolymer and an antistatic functional agent; The antistatic functional agent is composed of an ionic compound and a surfactant, and the addition ratio of the ionic compound to the surfactant satisfies: 2≤ionic compound / surfactant≤50; The urethane prepolymer is obtained by reacting a first polyol and an organic polyisocyanate compound, wherein the first polyol comprises a polyether polyol and a polyester polyol, and the addition ratio of the polyether polyol to the polyester polyol satisfies: 5≤polyether polyol / polyester polyol≤50.

2. The surface protection film according to claim 1, characterized in that: The addition ratio of the ionic compound to the surfactant satisfies: 2≤ionic compound / surfactant≤30; the addition ratio of the polyether polyol to the polyester polyol satisfies: 5≤polyether polyol / polyester polyol≤25.

3. The surface protection film according to claim 1, characterized in that The mass ratio of the ionic compound to the polyester polyol is 1:(1-10).

4. The surface protection film according to claim 1, characterized in that The crosslinking density of the urethane prepolymer is 76% to 80%.

5. The surface protection film according to claim 1, characterized in that: The molecular weight of the polyether polyol is 50,000-100,000, and the PDI is 5-10.

6. The surface protection film according to claim 1, characterized in that: The molecular weight of the polyester polyol is 30,000-80,000, and the PDI is 5-10.

7. The surface protection film according to claim 1, characterized in that The equivalent ratio of the NCO group of the organic polyisocyanate compound to the OH group of the first polyol is 1.0 to 2.0 in terms of NCO group / OH group.

8. The surface protection film according to claim 1, characterized in that The surface energy of the urethane prepolymer is 38 mN / m to 43 mN / m.

9. The surface protection film according to claim 1, characterized in that: The surfactant is a fluorine-based additive, specifically at least one selected from fluorine-containing compounds, fluorine-based compounds containing hydroxyl groups, and fluorine-based compounds containing crosslinkable functional groups.

10. The surface protection film according to claim 1, characterized in that The ionic compound is a combination of at least one of an onium cation and a metal cation and a fluorine organic anion.

11. The surface protection film according to claim 1, characterized in that: The content of the antistatic functional agent is 0.1% or more based on 100% by mass of the urethane adhesive composition.

12. The surface protection film according to claim 1, characterized in that: The urethane adhesive composition further includes a second polyol and a multifunctional isocyanate compound.

13. The surface protection film according to claim 1, characterized in that After the surface protection film is attached to glass, when the surface protection film is peeled off at a peeling speed of 15 m / min, the peeling charged voltage is less than 100V.

14. The surface protection film according to claim 1, characterized in that After the surface protection film was attached to the copper foil, the copper foil was tested at 20V for 15 minutes, and the copper foil showed no corrosion or yellowing.

15. An optical component, characterized in that: The surface protection film according to any one of claims 1 to 14 is attached to the surface of the optical member.

16. An electronic component, characterized in that: The surface protection film according to any one of claims 1 to 14 is attached to the surface of the electronic component.

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