Multilayer film

Abstract

Provided is a multilayer film which has at least a base material layer and a surface layer. The dynamic friction coefficient of the surface layer is 0.4 to 1.2, and the surface layer contains a polyurethane resin (U1) that is obtained by reacting an active hydrogen component (A1) which contains, as an essential component, a compound (a1) having a polyorganosiloxane group and an active hydrogen group, and an isocyanate component (B1) with each other. The dynamic friction coefficient of the base material layer is higher than 1.2, and the base material layer contains a polyurethane resin (U2) that is obtained by reacting an active hydrogen component (A2) and an isocyanate component (B2) with each other.

Description

Multi-layer film

[0001] The present invention relates to a multi-layer film.

[0002] Films with excellent scratch resistance and bending resistance have been proposed as cover films for use in displays and the like (see, for example, Patent Document 1). However, in recent years, displays have come to be required to be more flexible, making it necessary to achieve both scratch resistance and surface slipperiness and flexibility. Currently, there is no cover film for displays that satisfies all of these performance requirements.

[0003] Patent No. 7142167

[0004] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a multilayer film that has excellent flexibility at low temperatures, excellent surface slipperiness, and also excellent scratch resistance and flex resistance.

[0005] The present inventors have conducted extensive research to achieve the above object, and have arrived at the present invention. That is, the present invention relates to a multilayer film having at least a base layer and a surface layer, wherein the surface layer has a dynamic friction coefficient of 0.4 to 1.2 measured under the following conditions, and the surface layer contains a polyurethane resin (U1) obtained by reacting an active hydrogen component (A1) containing, as an essential component, a compound (a1) having a polyorganosiloxane group and an active hydrogen group with an isocyanate component (B1), and the urethane group concentration of the polyurethane resin (U1) (when urea groups are present, the total concentration of urethane groups and urea groups) is 1.0 to 1.8. a multilayer film, the base layer having a dynamic friction coefficient of greater than 1.2 measured under the following conditions, the base layer containing a polyurethane resin (U2) obtained by reacting an active hydrogen component (A2) with an isocyanate component (B2), the polyurethane resin (U2) having a urethane group concentration (total concentration of urethane groups and urea groups when urea groups are present) of 1.0 to 2.0 mmol / g, and the polyurethane resin (U2) having a crosslinking point concentration of 0.1 to 0.50 mmol / g calculated by the following calculation formula (1): <Method for measuring the dynamic friction coefficient> (1) A multilayer film cut into a rectangle measuring 100 mm in length, 50 mm in width, and 400 μm in thickness is fixed on a glass plate with the layer to be measured facing up. (2) After leaving the multilayer film at 23°C for 24 hours, the dynamic friction coefficient is measured using a Tribomaster TL201s and a tactile contactor manufactured by Trinity Labs Co., Ltd. under the following conditions: temperature 23°C, load 30 gf, speed 50 mm / s, and travel distance 50 mm. <Method for calculating crosslinking point concentration> Crosslinking point concentration of polyurethane resin (mmol / g) = (F-2) × (number of millimoles of tri- or higher functional monomers in 1 g of polyurethane resin) (1)

[0006] The multilayer film of the present invention has excellent flexibility at low temperatures, excellent surface slipperiness, and also excellent scratch resistance and flex resistance.

[0007] The present invention will be described in detail below.

[0008] <Surface Layer> The surface layer in the present invention has a dynamic friction coefficient of 0.4 to 1.2 measured under the measurement conditions described below, and contains a polyurethane resin (U1). The polyurethane resin (U1) has a urethane group concentration (when urea groups are present, the total concentration of urethane groups and urea groups) of 1.0 to 1.8 mmol / g, and is a polyurethane resin obtained by reacting an active hydrogen component (A1) containing a compound (a1) having a polyorganosiloxane group and an active hydrogen group as an essential component with an isocyanate component (B1).

[0009] Examples of the active hydrogen component (A1) in the polyurethane resin (U1) include a compound (a1) having a polyorganosiloxane group and an active hydrogen group as an essential component, and a polymer polyol (a2), a chain extender (a3), and a reaction terminator (a4) as optional components.

[0010] <Compound (a1) Having a Polyorganosiloxane Group and an Active Hydrogen Group> As the compound (a1) having a polyorganosiloxane group and an active hydrogen group, a compound having a polyorganosiloxane group represented by the general formula (1) is preferred from the viewpoint of scratch resistance and haze.

[0011] [In the formula, R １ ~R ６ each independently represents a hydrocarbon group having 1 to 6 carbon atoms, and n is an integer of 1 to 100.

[0012] R in general formula (1) １ ~R ６ R each independently represents a hydrocarbon group having 1 to 6 carbon atoms. １ ~R ６ From the viewpoint of scratch resistance, alkyl groups having 1 to 3 carbon atoms are preferred, and methyl groups are more preferred.

[0013] In the general formula (1), n ​​is an integer of 1 to 100, and from the viewpoints of scratch resistance and haze, it is preferably 5 to 80, and more preferably 10 to 60.

[0014] Examples of the active hydrogen group possessed by the compound (a1) having a polyorganosiloxane group and an active hydrogen group include a hydroxyl group, an amino group, and a carboxyl group. The compound (a1) having a polyorganosiloxane group and an active hydrogen group generally has low compatibility with other constituent monomers of the polyurethane resin (U1). Therefore, from the viewpoint of suppressing the increase in haze of the polyurethane resin (U1) by homogeneously introducing the compound (a1) having a polyorganosiloxane group and an active hydrogen group into the polyurethane resin (U1), it is preferable to use a compound (a1) having a hydroxyl group or an amino group as the active hydrogen group. The compound (a1) having a polyorganosiloxane group and an active hydrogen group may be used alone or in combination of two or more.

[0015] Among the compounds (a1) having a polyorganosiloxane group and an active hydrogen group, the compound (a11) having a hydroxyl group can be commercially available, for example, "KF-6001" (functional group equivalent 900 g / mol), "KF-6002" (functional group equivalent 1,600 g / mol), and "KF-6003" (functional group equivalent 2,550 g / mol) having hydroxyl groups at both ends (all manufactured by Shin-Etsu Chemical Co., Ltd.). "X-22-1Y-16-752A" (functional group equivalent weight 1,500 g / mol) having phenolic hydroxyl groups at both ends (all manufactured by DuPont Toray Specialty Materials Co., Ltd.), "X-22-170BX" (functional group equivalent weight 2,800 g / mol), "X-22-170DX" (functional group equivalent weight 4,670 g / mol), and "X-22-176DX" (functional group equivalent weight 1, 600 g / mol), "X-22-176F" (functional group equivalent 6,300 g / mol) (all manufactured by Shin-Etsu Chemical Co., Ltd.), "X-22-4039" (functional group equivalent 970 g / mol) and "X-22-4015" (functional group equivalent 1,870 g / mol) having hydroxyl groups on the side chains (all manufactured by Shin-Etsu Chemical Co., Ltd.), "SF8427" (functional group equivalent 930 g / mol) having hydroxyl groups in polyether at both ends Examples of such a copolymer include "X-22-4952" (functional group equivalent 1,100 g / mol, manufactured by Shin-Etsu Chemical Co., Ltd.), "FZ-2162" (functional group equivalent 750 g / mol) and "SH3773M" (functional group equivalent 800 g / mol) having a hydroxyl group in the side chain polyether (all manufactured by DuPont Toray Specialty Materials Co., Ltd.).

[0016] Of the compounds (a1) having a polyorganosiloxane group and an active hydrogen group, the compound (a12) having an amino group can be a commercially available product. For example, "KF-8010" (functional group equivalent per amino group: 430 g / mol), "X-22-161A" (functional group equivalent per amino group: 800 g / mol), and "X-22-161B" (functional group equivalent per amino group: 100 g / mol) are available. functional group equivalent per amino group: 1,500 g / mol), "KF-8012" (functional group equivalent per amino group: 2,200 g / mol), "KF-8008" (functional group equivalent per amino group: 5,700 g / mol), "X-22-9409" (functional group equivalent per amino group: 700 g / mol), "X-22-1660B-3" (functional group equivalent per amino group: 2,200 g / mol) (all manufactured by Shin-Etsu Chemical Co., Ltd.) "BY-16-853" (functional group equivalent per amino group: 650 g / mol), "BY-16-853B" (functional group equivalent per amino group: 2,200 g / mol), "BY-16-853U" (functional group equivalent per amino group: 450 g / mol) (all manufactured by DuPont Toray Specialty Materials Co., Ltd.), "KF-868" (functional group equivalent per amino group: 1,000 g / mol) having an amino group in the side chain equivalent weight 8,800 g / mol), "KF-865" (functional group equivalent weight per amino group 5,000 g / mol), "KF-864" (functional group equivalent weight per amino group 3,800 g / mol), "KF-880" (functional group equivalent weight per amino group 1,800 g / mol), and "KF-8004" (functional group equivalent weight per amino group 1,500 g / mol) (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0017] Of the compounds (a1) having a polyorganosiloxane group and an active hydrogen group, the compound (a13) having a carboxyl group can be a commercially available product. For example, "X-22-162C" (functional group equivalent 2,300 g / mol) having a carboxyl group at both ends, "X-22-3710" (functional group equivalent 1,450 g / mol) having a carboxyl group at one end, and "X-22-3701E" (functional group equivalent 4,000 g / mol) having a carboxyl group on the side chain (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0018] Among the compounds (a1) having a polyorganosiloxane group and an active hydrogen group in the polyurethane resin (U1), from the viewpoint of haze and surface slipperiness, preferred are compounds having a hydroxyl group and an amino group, more preferred are compounds having an amino group, and particularly preferred are BY-16-853U and KF-8012.

[0019] The weight proportion of the compound (a1) having a polyorganosiloxane group and an active hydrogen group in the polyurethane resin (U1) is preferably 0.5 to 5% by weight, more preferably 1 to 4% by weight, based on the weight of the polyurethane resin (U1) as a constituent from the viewpoints of scratch resistance, tack-free properties and haze.

[0020] <High polymer polyol (a2)> The high polymer polyol (a2) is preferably a high polymer polyol having a number average molecular weight (hereinafter abbreviated as Mn) of 500 or more, and specific examples thereof include polyester polyol (a21), polyether polyol (a22), polyether ester polyol (a23), polycarbonate polyol (a24), polyester carbonate polyol (a25), etc. The high polymer polyol (a2) may be used alone or in combination of two or more.

[0021] Examples of the polyester polyol (a21) include condensation type polyester polyols and polylactone polyols.

[0022] Examples of the condensation type polyester polyol include those obtained by condensing a polyol having an Mn or a chemical formula weight of less than 500 with a polycarboxylic acid having 2 to 20 carbon atoms or an ester-forming derivative thereof [such as an acid anhydride, a lower (1 to 4 carbon atoms) alkyl ester, or an acid halide].

[0023] Examples of the polyol having an Mn or chemical formula weight of less than 500 include polyhydric alcohols having 2 to 20 carbon atoms; adducts of polyhydric alcohols having 2 to 20 carbon atoms with alkylene oxides (hereinafter abbreviated as AO) having 2 to 12 carbon atoms, with an Mn or chemical formula weight of less than 500; adducts of bisphenols (such as bisphenol A, bisphenol S, and bisphenol F) with AO having 2 to 12 carbon atoms, with an Mn or chemical formula weight of less than 500; and bis(2-hydroxyethyl) terephthalate and its adducts with AO having 2 to 12 carbon atoms, with an Mn or chemical formula weight of less than 500.

[0024] Examples of the AO having 2 to 12 carbon atoms include ethylene oxide, 1,2- or 1,3-propylene oxide, 1,2-, 1,3- or 2,3-butylene oxide, tetrahydrofuran, 3-methyltetrahydrofuran, styrene oxide, α-olefin oxide, and epichlorohydrin.

[0025] Examples of the polyhydric alcohol having 2 to 20 carbon atoms include linear or branched aliphatic dihydric alcohols having 2 to 12 carbon atoms [linear alcohols such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, diethylene glycol, triethylene glycol, and tetraethylene glycol; 1,2-, 1,3-, or 2,3-butanediol; 2-methyl-1,4-propanediol; branched alcohols such as 2-methyl-1,5-pentanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,6-hexanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, and 4-methyloctanediol; alicyclic dihydric alcohols having 6 to 20 prime numbers [1,4-cyclohexanediol, 1,3- or 1,4-cyclohexanedimethanol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 2,5-bis(hydroxymethyl)-1,4-dioxane, 2,7-norbornanediol, tetrahydrofuran dimethanol, 1,4-bis(hydroxyethoxy)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2-bis(4-hydroxycyclohexyl)propane, etc.]; aromatic aliphatic dihydric alcohols having 8 to 20 carbon atoms [1,4-cyclohexanediol, 1,3- or 1,4-cyclohexanedimethanol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 2,5-bis(hydroxymethyl)-1,4-dioxane, 2,7-norbornanediol, tetrahydrofuran dimethanol, 1,4-bis(hydroxyethoxy)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2-bis(4-hydroxycyclohexyl)propane, etc.]; Examples of suitable alcohols include hydric alcohols (e.g., m- or p-xylylenediol, bis(hydroxyethyl)benzene, and bis(hydroxyethoxy)benzene); trihydric alcohols having 3 to 20 carbon atoms (e.g., aliphatic triols (e.g., glycerin and trimethylolpropane)); tetrahydric to octahydric alcohols having 5 to 20 carbon atoms (e.g., aliphatic polyols (e.g., pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, and dipentaerythritol)); and sugars (e.g., sucrose, glucose, mannose, fructose, methyl glucoside, and derivatives thereof).

[0026] Examples of the polycarboxylic acid having 2 to 20 carbon atoms or an ester-forming derivative thereof include aliphatic dicarboxylic acids (succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, decylsuccinic acid, fumaric acid, maleic acid, etc.), alicyclic dicarboxylic acids (dimer acid, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, phthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, etc.), trivalent or higher polycarboxylic acids (trimellitic acid, pyromellitic acid, etc.), anhydrides thereof (succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, etc.), acid halides thereof (adipic acid dichloride, etc.), low-molecular-weight alkyl esters thereof (dimethyl succinate, dimethyl phthalate, etc.), and combinations of these.

[0027] Examples of the polylactone polyol include those obtained by ring-opening polymerization of lactone monomers having 3 to 12 carbon atoms (such as β-propiolactone, γ-butyrolactone, γ-valerolactone, ε-caprolactone, η-caprylolactone, 11-undecanolactone, and 12-tridecanoid) using the above-mentioned polyhydric alcohols having 2 to 20 carbon atoms as an initiator. One type of lactone monomer may be used alone, or two or more types may be used in combination.

[0028] Examples of the polyether polyol (a22) include compounds in which an AO having 2 to 12 carbon atoms is added to the above-mentioned polyol having an Mn or a chemical formula weight of less than 500. The AO may be used alone or in combination of two or more kinds, and in the latter case, may be block addition (such as a chip type, a balanced type, or an active secondary type), random addition, or a combination of these.

[0029] The addition of AO to the polyol having an Mn or a chemical formula weight of less than 500 is carried out, for example, in the absence of a catalyst or in the presence of a catalyst (an alkali catalyst, an amine catalyst, an acidic catalyst, or the like) (particularly in the latter stage of the AO addition) at normal or elevated pressure in one stage or multiple stages.

[0030] Specific examples of the polyether polyol (a22) include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly(oxy-3-methyltetramethylene) glycol, tetrahydrofuran / ethylene oxide copolymer diol, and tetrahydrofuran / 3-methyltetrahydrofuran copolymer diol.

[0031] Examples of the polyether ester polyol (a23) include those obtained by condensation polymerization of one or more of the above-mentioned polyether polyols with one or more of the polycarboxylic acids having 2 to 20 carbon atoms or ester-forming derivatives thereof exemplified as raw materials for the above-mentioned condensation-type polyester polyols.

[0032] Examples of the polycarbonate polyol (a24) include polycarbonate polyols produced by condensing one or more (preferably 2 to 4) polyhydric alcohols having 2 to 20 carbon atoms (preferably polyhydric alcohols having 3 to 9 carbon atoms, more preferably aliphatic dihydric alcohols having 4 to 6 carbon atoms) with a low molecular weight carbonate compound (for example, a dialkyl carbonate in which the alkyl group has 1 to 6 carbon atoms, an alkylene carbonate having an alkylene group having 2 to 6 carbon atoms, and a diaryl carbonate having an aryl group having 6 to 9 carbon atoms) while causing a dealcoholization reaction.

[0033] Specific examples of the polycarbonate polyol (a24) include Nipporan 980R [polyhexamethylene carbonate diol having Mn=2,000, manufactured by Tosoh Corporation], Kuraray Polyol C-1090 [poly(3-methyl-5-pentanediol / hexamethylene) carbonate diol having Mn=1,000, manufactured by Kuraray Co., Ltd.], Kuraray Polyol C-2090 [poly(3-methyl-5-pentanediol / hexamethylene) carbonate diol having Mn=2,000, manufactured by Kuraray Co., Ltd.], and Kuraray Polyol C-3090 [poly(3-methyl-5-pentanediol / hexamethylene) carbonate diol having Mn=3,000, manufactured by Kuraray Co., Ltd.]. and Duranol G4672 [poly(tetramethylene / hexamethylene) carbonate diol having Mn=2,000, manufactured by Asahi Kasei Corporation], Duranol T5652 [poly(pentamethylene / hexamethylene) carbonate diol having Mn=2,000, manufactured by Asahi Kasei Corporation], and Duranol T5651 [poly(pentamethylene / hexamethylene) carbonate diol having Mn=1,000, manufactured by Asahi Kasei Corporation].

[0034] Examples of the polyester carbonate polyol (a25) include those obtained by reacting the above polycarbonate polyol (a24) with a lactone monomer (β-propiolactone, γ-butyrolactone, γ-valerolactone, ε-caprolactone, η-caprylolactone, 11-undecanolactone, 12-tridecanoid, etc.).

[0035] Specific examples of polyester carbonate polyols (a25) include Desmophen (registered trademark) C 1200 (manufactured by Bayer Material Science), ETERNACOLL (registered trademark) UHC50-200 (polycaprolactone-modified hexamethylene carbonate diol having Mn=2,000, manufactured by UBE Co., Ltd.), and ETERNACOLL (registered trademark) UHC50-100 (polycaprolactone-modified hexamethylene carbonate diol having Mn=1,000, manufactured by UBE Co., Ltd.).

[0036] Among the polymer polyols (a2) in the polyurethane resin (U1), polycarbonate polyols (a24) and polyester carbonate polyols (a25) are particularly preferred from the viewpoints of scratch resistance, tack-free properties, chemical resistance, and flexibility at low temperatures.

[0037] From the viewpoint of scratch resistance, the Mn of the high molecular weight polyol (a2) is preferably 500 or more, more preferably 500 to 5,000, and particularly preferably 800 to 3,000.

[0038] The Mn of the polymer polyol (a2) in the present invention can be measured by gel permeation chromatography, for example, under the following conditions: Apparatus: "Waters Alliance 2695" [manufactured by Waters] Column: "Guard column Super H-L" (1 column), "TSKgel Super H2000, TSKgel Super H3000, TSKgel Super H4000 (all manufactured by Tosoh Corporation) - one column each connected together" Sample solution: 0.25 wt % tetrahydrofuran solution Solution injection amount: 10 μl Flow rate: 0.6 ml / min Measurement temperature: 40° C. Detector: refractive index detector Reference material: standard polyethylene glycol

[0039] From the viewpoint of abrasion resistance and tack-free properties, the weight of the high molecular weight polyol (a2) in the polyurethane resin (U1) is preferably 50 to 90% by weight, more preferably 60 to 80% by weight, based on the weight of the polyurethane resin (U1) as a constituent component.

[0040] <Chain Extender (a3)> Examples of the chain extender (a3) ​​include water, the above-mentioned polyols having an Mn or chemical formula weight of less than 500, and polyamine compounds having an Mn or chemical formula weight of less than 500.

[0041] Examples of the polyol having an Mn or a chemical formula weight of less than 500 include the same polyols having an Mn or a chemical formula weight of less than 500 that constitute the condensation type polyester polyols.

[0042] Examples of the polyamine compound having an Mn or a chemical formula weight of less than 500 include aliphatic polyamines having 2 to 36 carbon atoms (alkylenediamines such as ethylenediamine and hexamethylenediamine; poly(n=2 to 6) alkylene group (carbon number 2 to 6) poly(n=3 to 7) amines such as diethylenetriamine, dipropylenetriamine, dihexylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine), alicyclic polyamines having 6 to 20 carbon atoms (1,3- or 1,4-diaminocyclohexane, 4,4'- or 2,4'-dicyclohexylmethanediamine, and isophoronediamine), and aromatic polyamines having 6 to 20 carbon atoms (1,3- or 1,4-phenylenediamine). and aromatic aliphatic polyamines having 8 to 20 carbon atoms [1,3- or 1,4-xylylenediamine, bis(aminoethyl)benzene, bis(aminopropyl)benzene, bis(aminobutyl)benzene, etc.], heterocyclic polyamines having 3 to 20 carbon atoms [2,4-diamino-1,3,5-triazine, piperazine, N-(2-aminoethyl)piperazine, etc.], hydrazine or a derivative thereof (dibasic acid dihydrazide, for example, adipic acid dihydrazide, etc.), and amino alcohols having 2 to 20 carbon atoms (for example, ethanolamine, diethanolamine, 2-amino-2-methylpropanol, triethanolamine).

[0043] Of the chain extenders (a3), water, ethylene glycol, 1,4-butanediol, and trimethylolpropane are preferred from the viewpoint of scratch resistance and tack-free properties.

[0044] From the viewpoint of abrasion resistance and tack-free properties, the weight of the chain extender (a3) ​​in the polyurethane resin (U1) is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the weight of the polyurethane resin (U1) as a constituent component.

[0045] <Reaction Terminator (a4)> Examples of the reaction terminator (a4) include monoalcohols having 1 to 20 carbon atoms (methanol, ethanol, butanol, octanol, decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, etc.), and monoamines having 1 to 20 carbon atoms (mono- or di-alkylamines such as monomethylamine, monoethylamine, monobutylamine, dibutylamine, monooctylamine, etc., and mono- or di-alkanolamines such as monoethanolamine, diethanolamine, diisopropanolamine, etc.).

[0046] Of the reaction terminators (a4), monoethanolamine and diethanolamine are preferred from the viewpoint of scratch resistance and tack-free properties.

[0047] The weight of the reaction terminator (a4) in the polyurethane resin (U1) is preferably 0.05 to 0.1% by weight, more preferably 0.3 to 0.85% by weight, based on the weight of the polyurethane resin (U1) as a constituent, from the viewpoint of scratch resistance and tack-free properties.

[0048] <Isocyanate Component (B1)> Examples of the isocyanate component (B1) include aromatic isocyanates (b1) having 8 to 26 carbon atoms and having 2, 3 or more isocyanate groups, aliphatic isocyanates (b2) having 4 to 22 carbon atoms, alicyclic isocyanates (b3) having 8 to 18 carbon atoms, araliphatic isocyanates (b4) having 10 to 18 carbon atoms, and modified products (b5) of these organic isocyanates.

[0049] Examples of the aromatic isocyanate (b1) having 8 to 26 carbon atoms include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (hereinafter, tolylene diisocyanate will be abbreviated as TDI), crude TDI, 4,4'- or 2,4'-diphenylmethane diisocyanate (hereinafter, diphenylmethane diisocyanate will be abbreviated as MDI), crude MDI, polyaryl polyisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4',4'-triphenylmethane triisocyanate, and m- or p-isocyanatophenylsulfonyl isocyanate.

[0050] Examples of the aliphatic isocyanate (b2) having 4 to 22 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

[0051] Examples of the alicyclic isocyanate (b3) having 8 to 18 carbon atoms include isophorone diisocyanate (hereinafter abbreviated as IPDI), 4,4'-dicyclohexylmethane diisocyanate (hereinafter abbreviated as hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, and 2,5- or 2,6-norbornane diisocyanate.

[0052] Examples of the aralkyl isocyanate (b4) having 10 to 18 carbon atoms include m- or p-xylylene diisocyanate and α,α,α',α'-tetramethylxylylene diisocyanate.

[0053] Examples of the organic isocyanate modified products (b5) of aromatic isocyanates (b1) having 8 to 26 carbon atoms, aliphatic isocyanates (b2) having 4 to 22 carbon atoms, alicyclic isocyanates (b3) having 8 to 18 carbon atoms, and aromatic aliphatic polyisocyanates (b4) having 10 to 18 carbon atoms include modified products of the above polyisocyanates containing a urethane group, a carbodiimide group, an allophanate group, a urea group, a biuret group, a uretdione group, a uretoimine group, an isocyanurate group, or an oxazolidone group [for example, modified MDI (urethane-modified MDI, carbodiimide-modified MDI, trihydrocarbyl phosphate-modified MDI, etc.), urethane-modified TDI, biuret-modified HDI, isocyanurate-modified HDI, and isocyanurate-modified IPDI].

[0054] Of the isocyanate components (B1) in the polyurethane resin (U1), from the viewpoint of scratch resistance, preferred are alicyclic isocyanates (b3) having 8 to 18 carbon atoms and aromatic polyisocyanates (b1) having 8 to 26 carbon atoms, more preferred are aromatic diisocyanates having 8 to 26 carbon atoms and alicyclic diisocyanates having 8 to 18 carbon atoms, and particularly preferred are hydrogenated MDI and MDI. The isocyanate component (B1) may be used alone or in combination of two or more types.

[0055] From the viewpoint of abrasion resistance and tack-free properties, the weight of the isocyanate component (B1) in the polyurethane resin (U1) is preferably 5 to 40% by weight, more preferably 15 to 35% by weight, based on the weight of the polyurethane resin (U1) as a constituent component.

[0056] The crosslinking point concentration of the polyurethane resin (U1) is preferably 0.01 to 0.20 mmol / g from the viewpoint of abrasion resistance, and the urethane group concentration in the polyurethane resin (U1) (when urea groups are present, the total concentration of urethane groups and urea groups) is 1.0 to 1.8 mmol / g, and preferably 1.0 to 1.5 mmol / g from the viewpoint of abrasion resistance and surface slipperiness.

[0057] The urethane group concentration and urea group concentration of polyurethane resin are determined based on the N atom content determined by a nitrogen analyzer.１ It can be calculated from the ratio of urethane groups to urea groups, as well as the contents of allophanate groups and biuret groups, which are quantified by H-NMR. First, the total amount of N atoms derived from "urethane groups" and "urea groups" is calculated by subtracting the amount of N atoms derived from "allophanate groups" and "biuret groups" from the "N atom content." Next, the amounts of N atoms derived from "urethane groups" and "urea groups" are calculated from the ratio of urethane groups to urea groups. From these values, the urethane group concentration and the urea group concentration are calculated, respectively. In this embodiment, the urethane group concentration and the urea group concentration of the polyurethane resin can be measured as follows.

[0058] (Urethane group concentration and urea group concentration of polyurethane resin) The urethane group concentration and urea group concentration of polyurethane resin were determined by the N atom content quantified by a nitrogen analyzer [ANTEK7000 (manufactured by Antec Co., Ltd.)]. １ It is calculated from the ratio of urethane groups to urea groups determined by H-NMR, and the allophanate group and biuret group contents described below. １ The H-NMR measurement is carried out according to the method described in "Structural Study of Polyurethane Resins by NMR: Takeda Research Institute Bulletin 34(2), 224-323 (1975)". １ H-NMR is measured, and when an aliphatic isocyanate is used, the mass ratio of urea groups to urethane groups is measured from the ratio of the integrated amount of hydrogen derived from urea groups at a chemical shift of around 6 ppm to the integrated amount of hydrogen derived from urethane groups at a chemical shift of around 7 ppm, and the urethane group and urea group contents are calculated from this mass ratio, the above-mentioned N atom content, and the allophanate group and biuret group contents.When an aromatic isocyanate is used, the mass ratio of urea groups to urethane groups is calculated from the ratio of the integrated amount of hydrogen derived from urea groups at a chemical shift of around 8 ppm to the integrated amount of hydrogen derived from urethane groups at a chemical shift of around 9 ppm, and the urethane group and urea group contents are calculated from this mass ratio, the above-mentioned N atom content, and the allophanate group and biuret group contents.

[0059] (Allophanate Group and Biuret Group Content) The total allophanate group and biuret group content of a polyurethane resin is calculated using a gas chromatograph [Shimadzu GC-9A (Shimadzu Corporation)]. 50 g of a DMF solution containing 0.01% by mass of di-n-butylamine and 0.01% by mass of naphthalene (internal standard) is prepared. A sample of the polyurethane resin is weighed into a stoppered test tube, 2 g of the above DMF solution is added, and the test tube is heated in a constant temperature water bath at 90°C for 2 hours. After cooling to room temperature, 10 μL of acetic anhydride is added and the mixture is shaken and stirred for 10 minutes. 50 μL of di-n-propylamine is further added, and the mixture is shaken for 10 minutes. Gas chromatographic measurement is then performed under the following conditions. A blank measurement is also performed in parallel, and the amount of amine consumed is determined from the difference with the test value, and the total allophanate group and biuret group content is measured.

[0060] (Gas chromatograph conditions) Apparatus: Shimadzu GC-9A Column: 10% PEG-20M on Chromosorb WAW DMLS 60 / 80 mesh glass column 3 mmφ×2 m Column temperature: 160° C. Sample inlet temperature: 200° C. Carrier gas: nitrogen 40 mL / min Detector: FID Sample injection amount: 2 μL

[0061] (Calculation Formula for Sum of Allophanate Group and Biuret Group Contents) The sum of the allophanate group and biuret group contents can be calculated by the following formula: Sum of Allophanate Group and Biuret Group Contents (g) = {(B - A) / B} × 0.00155 / S, where A is the (peak area of ​​di-n-butylacetamide / peak area of ​​naphthalene) of the sample, B is the (peak area of ​​di-n-butylacetamide / peak area of ​​naphthalene) of the blank, and S is the amount (g) of polyurethane urea resin (U) collected.

[0062] The crosslinking point concentration (unit: mmol / g) of the polyurethane resin (U1) in the present invention is a value calculated by calculating (F-2) x {the number of millimoles of the tri- or higher functional constituent monomers in 1 g of the polyurethane resin (U1)} for each of the tri- or higher functional constituent monomers, where F is the number of functional groups of the tri- or higher functional constituent monomers used in the polyurethane resin (U1), and then taking the sum of the calculated values.

[0063] <Method for producing polyurethane resin (U1)> The method for producing the polyurethane resin (U1) in the present invention is not particularly limited, and examples thereof include a method of previously producing a urethane prepolymer using an active hydrogen component (A1), an isocyanate component (B1), and if necessary, an organic solvent, and then reacting the urethane prepolymer with a chain extender (a3), and a method of charging the active hydrogen component (A1), the isocyanate component (B1), and if necessary, an organic solvent all at once into a batch reaction vessel and heating to react. The method for producing the urethane prepolymer is not particularly limited, and examples thereof include a method of mixing the active hydrogen component (A1) and the isocyanate component (B1) in a kneader in the absence of a solvent, and then heating to react, and a method of mixing the active hydrogen component (A1) and the isocyanate component (B1) in a batch reaction vessel equipped with a stirrer in the presence or absence of an organic solvent, and then heating to react.

[0064] In the production method of polyurethane resin (U1), an organic solvent can be used in any of the production steps. The organic solvent is not particularly limited, and examples thereof include ketone solvents having 3 to 10 carbon atoms (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ester solvents having 2 to 10 carbon atoms (ethyl acetate, butyl acetate, γ-butyrolactone, etc.), ether solvents having 4 to 10 carbon atoms (dioxane, tetrahydrofuran, ethyl cellosolve, diene glycol dimethyl ether, etc.), amide solvents having 3 to 10 carbon atoms (N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, etc.), sulfoxide solvents having 2 to 10 carbon atoms (dimethyl sulfoxide, etc.), alcohol solvents having 1 to 8 carbon atoms (methanol, ethanol, isopropyl alcohol, octanol, etc.), and hydrocarbon solvents having 4 to 10 carbon atoms (cyclohexane, toluene, xylene, etc.). The organic solvents may be used alone or in combination of two or more.

[0065] Of these, N,N-dimethylformamide, methyl ethyl ketone and toluene are preferred from the viewpoint of solubility.

[0066] When an organic solvent is used, the amount used is preferably an amount that results in a concentration of the polyurethane resin (U1) of 10 to 70% by weight, more preferably an amount that results in a concentration of 15 to 50% by weight.

[0067] Furthermore, in producing the polyurethane resin (U1), a catalyst may be added, if necessary, to promote the reaction. Specific examples of the catalyst include organometallic compounds (dibutyltin dilaurate, dioctyltin dilaurate, bismuth carboxylate, bismuth alkoxide, and chelate compounds of bismuth with a compound having a dicarbonyl group, etc.), inorganic metal compounds (bismuth oxide, bismuth hydroxide, bismuth halides, etc.), amines (triethylamine, triethylenediamine, 1,8-diazabicyclo[5.4.0]-7-undecene, etc.), and combinations of two or more of these.

[0068] <Inorganic Particles (C)> The surface layer may contain inorganic particles (C) as needed. Examples of the inorganic particles (C) include inorganic oxides such as alumina, silica, zirconia, magnesia, ceria, yttria, zinc oxide, and iron oxide; inorganic nitrides such as silicon nitride, titanium nitride, and boron nitride; ceramics such as silicon carbide, calcium carbonate, magnesium sulfate, aluminum sulfate, aluminum hydroxide, aluminum oxide hydroxide, potassium titanate, talc, kaolinite, dickite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amesite, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate, diatomaceous earth, and silica sand; particles containing glass fibers, etc., and combinations of two or more of these.

[0069] Among these, from the viewpoint of surface slipperiness and scratch resistance, inorganic oxide particles are preferred, silica or zirconia are more preferred, and silica is particularly preferred.

[0070] The volume average particle size of the inorganic particles (C) is preferably 10 to 80 nm, more preferably 10 to 50 nm, from the viewpoint of haze.

[0071] When inorganic particles (C) are used, the amount used is preferably 5 to 50% by weight, more preferably 15 to 50% by weight, based on the weight of the surface layer, from the viewpoints of surface slipperiness and haze.

[0072] <Additives (D)> The surface layer may contain additives (D) such as antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, adsorbents, mold release agents, and flame retardants, as required.

[0073] Examples of antioxidants include hindered phenol compounds (pentaerythristyl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, etc.), phosphorus compounds (tris(2,4-di-t-butylphenyl)phosphite, etc.), and sulfur compounds (pentaerythristyl-tetrakis(3-laurylthiopropionate), dilauryl-3,3′-thiodipropionate, etc.).

[0074] Examples of the ultraviolet absorber include benzotriazole compounds [2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, etc.].

[0075] Examples of the light stabilizer include hindered amine compounds [(bis-2,2,6,6-tetramethyl-4-piperidyl) sebacate, etc.].

[0076] Examples of plasticizers include phthalate esters (dibutyl phthalate, dioctyl phthalate, dibutyl benzyl phthalate, diisodecyl phthalate, etc.); aliphatic dibasic acid esters (di-2-ethylhexyl adipate, 2-ethylhexyl sebacate, etc.); trimellitate esters (tri-2-ethylhexyl trimellitate, trioctyl trimellitate, etc.); fatty acid esters (butyl oleate, etc.); aliphatic phosphate esters (trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, tributary phosphate, etc.); aromatic phosphate esters [triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, tris(2,6-dimethylphenyl)phosphate, etc.]; halogen aliphatic phosphate esters [tris(chloroethyl)phosphate, tris(β-chloropropyl)phosphate, tris(dichloropropyl)phosphate, tris(tribromoneopentyl)phosphate, etc.]; and the like.

[0077] Examples of the adsorbent include alumina, silica gel, and molecular sieves.

[0078] As the release agent, known release agents can be used, and examples thereof include fluorine compound-type release agents [triperfluoroalkyl (having 8 to 20 carbon atoms) phosphate esters (triperfluorooctyl phosphate, triperfluorododecyl phosphate, etc.)]; silicone compound-type release agents (dimethylpolysiloxane, amino-modified dimethylpolysiloxane, carboxyl-modified dimethylpolysiloxane, etc.); fatty acid ester-type release agents [mono- or polyhydric alcohol esters of fatty acids having 10 to 24 carbon atoms (butyl stearate, hydrogenated castor oil, ethylene glycol monostearate, etc.)]; aliphatic acid amide-type release agents [mono- or bisamides of fatty acids having 8 to 24 carbon atoms (oleic acid amide, palmitic acid amide, stearic acid amide, distearic acid amides such as ethylenediamine, etc.)]; metal soaps (magnesium stearate, zinc stearate, etc.); natural or synthetic waxes (paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, etc.);

[0079] Examples of the flame retardant include a halogen-containing flame retardant, a phosphorus-containing flame retardant, an antimony-containing flame retardant, and a metal hydroxide-containing flame retardant.

[0080] When additive (D) is used, the amount used is preferably 0.5 to 5.0% by weight, more preferably 0.5 to 3.0% by weight, based on the weight of the surface layer.

[0081] <Dynamic Friction Coefficient of Surface Layer> The dynamic friction coefficient of the surface layer is 0.4 to 1.2, and from the viewpoint of surface slipperiness, it is preferably 0.4 to 0.85. The dynamic friction coefficient of the surface layer can be adjusted by the content of the inorganic particles (C) of the surface layer and the content of the compound (a1) having a polyorganosiloxane group and an active hydrogen group constituting the polyurethane resin (U1). <Method for Measuring the Dynamic Friction Coefficient> (1) A rectangular multilayer film cut into a length of 100 mm, a width of 50 mm, and a thickness of 400 μm is fixed on a glass plate with the surface layer facing up. (2) After leaving the multilayer film in a room temperature-controlled at 23 ° C for 24 hours, the dynamic friction coefficient is measured using a Tribomaster TL201s and a tactile contactor manufactured by Trinity Labs Co., Ltd. under the conditions of a temperature of 23 ° C, a load of 30 gf, a speed of 50 mm / s, and a travel distance of 50 mm.

[0082] <Substrate Layer> The substrate layer in the present invention contains a polyurethane resin (U2) and has a dynamic friction coefficient of more than 1.2, measured by the measurement method described below. The polyurethane resin (U2), which is a main constituent of the substrate layer, is a polyurethane resin having a urethane group concentration (when urea groups are present, the total concentration of urethane groups and urea groups) of 1.0 to 2.0 mmol / g and a crosslinking point concentration of 0.1 to 0.50 mmol / g, which is obtained by reacting an active hydrogen component (A2) with an isocyanate component (B2).

[0083] The active hydrogen component (A2) in the polyurethane resin (U2) preferably contains a polymer polyol (a2). The polymer polyol (a2) means the polymer polyol (a2) described in the polyurethane resin (U1).

[0084] From the viewpoints of adjusting the elastic recovery rate within a predetermined range and suitably imparting scratch resistance and flex resistance, the high molecular weight polyol (a2) preferably contains a polyester polyol (a21) or a polyether polyol (a22), more preferably contains a polylactone polyol, polytetramethylene glycol, poly(oxy-3-methyltetramethylene) glycol, or tetrahydrofuran / 3-methyltetrahydrofuran copolymer diol, and particularly preferably contains polytetramethylene glycol.

[0085] The Mn of the high molecular weight polyol (a2) in the polyurethane resin (U2) is preferably 500 or more, more preferably 500 to 5,000, and particularly preferably 800 to 4,000, from the viewpoint of scratch resistance.

[0086] From the viewpoint of abrasion resistance and flex resistance, the weight proportion of the high molecular weight polyol (a2) in the polyurethane resin (U2) is preferably 50 to 90% by weight, more preferably 60 to 85% by weight, based on the weight of the polyurethane resin (U2) as a constituent component.

[0087] The active hydrogen component (A2) may optionally contain a chain extender (a3) ​​and a reaction terminator (a4). The chain extender (a3) ​​may be selected from the chain extenders (a3) ​​described for the polyurethane resin (U1). The reaction terminator (a4) may be selected from the reaction terminators (a4) described for the polyurethane resin (U1).

[0088] From the viewpoint of abrasion resistance and flex resistance, the weight of the chain extender (a3) ​​in the polyurethane resin (U2) is preferably 0.5 to 20% by weight, more preferably 1 to 10% by weight, based on the weight of the polyurethane resin (U2) as a constituent component.

[0089] From the viewpoint of abrasion resistance and flex resistance, the weight of the chain extender (a4) in the polyurethane resin (U2) is preferably 0.05 to 0.1% by weight, more preferably 0.3 to 0.85% by weight, based on the weight of the polyurethane resin (U2) as a constituent component.

[0090] <Isocyanate component (B2)> As the isocyanate component (B2), the isocyanate component (B1) described in the polyurethane resin (U1) can be appropriately selected and used. Among them, from the viewpoint of scratch resistance, aromatic isocyanates (b1) having 8 to 26 carbon atoms and aliphatic isocyanates (b2) having 4 to 22 carbon atoms are preferred, and hexamethylene diisocyanate and MDI are particularly preferred.

[0091] From the viewpoint of abrasion resistance and flex resistance, the weight of the isocyanate component (B2) in the polyurethane resin (U2) is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, based on the weight of the polyurethane resin (U2) as a constituent component.

[0092] From the viewpoint of abrasion resistance, the crosslinking point concentration of the polyurethane resin (U2) is 0.1 to 0.50 mmol / g, and from the viewpoint of abrasion resistance, the urethane group concentration in the polyurethane resin (U2) (if urea groups are present, the total concentration of urethane groups and urea groups) is preferably 1.0 to 2.0 mmol / g. If the crosslinking point concentration of the polyurethane resin (U2) is less than 0.1 mmol / g, the abrasion resistance will be insufficient, and if it exceeds 0.50 mmol / g, the flexibility will be insufficient. Note that the crosslinking point concentration (unit: mmol / g) of the polyurethane resin (U2) in the present invention is a value calculated by multiplying (F-2) by {the number of millimoles of the trifunctional or higher functional monomer per 1 g of the polyurethane resin (U2)} for each trifunctional or higher functional monomer, where F is the number of functional groups of the trifunctional or higher functional monomer used in the polyurethane resin (U2), and then taking the sum of the calculated values.

[0093] The method for producing the polyurethane resin (U2) of the present invention is not particularly limited, and the same method as the method for producing the polyurethane resin (U1) can be used, except that the polyurethane resin (U2) contains the active hydrogen component (A2) and the isocyanate component (B2).

[0094] In addition, in producing the polyurethane resin (U2), the catalyst used in the production method of the polyurethane resin (U1) may be contained, if necessary, in order to promote the reaction.

[0095] The substrate layer contains the polyurethane resin (U2) as an essential component, and may contain the additive (D) used in the production method of the polyurethane resin (U1) as needed.

[0096] When additive (D) is used, the amount used is preferably 1.0 to 5.0% by weight, more preferably 1.0 to 3.0% by weight, based on the weight of the substrate layer.

[0097] The dynamic friction coefficient of the substrate layer is greater than 1.2, and preferably 1.5 or greater from the viewpoints of abrasion resistance and flexibility at low temperatures. The dynamic friction coefficient of the substrate layer may be, for example, 10 or less. The dynamic friction coefficient of the substrate layer can be adjusted by the urethane group concentration of the polyurethane resin (U2) of the substrate layer and the crosslinking point concentration of the polyurethane resin (U2) of the substrate layer.

[0098] <Multilayer Film> The multilayer film of the present invention has at least a base layer and a surface layer. The thickness of the surface layer is preferably 0.5 to 50 μm, more preferably 1 to 15 μm, from the viewpoints of haze, scratch resistance, and surface slipperiness. The thickness of the base layer is preferably 100 to 1,000 μm, more preferably 250 to 600 μm, from the viewpoints of scratch resistance and flex resistance.

[0099] From the viewpoint of flexibility at low temperatures, the multilayer film of the present invention preferably has a difference of 0.5 to 10% between the indentation creep rate (CIT) from the surface layer at 25°C and the indentation creep rate (CIT) from the surface layer at -10°C. The difference between the indentation creep rate (CIT) from the surface layer of the multilayer film at 25°C and the indentation creep rate (CIT) from the surface layer at -10°C is particularly preferably 0.5 to 7.5%, and most preferably 0.5 to 5%. The difference between the indentation creep rate (CIT) from the surface layer of the multilayer film at 25°C and the indentation creep rate (CIT) from the surface layer at -10°C can be adjusted by the urethane group concentration of the polyurethane resin (U1) (the total concentration of urethane groups and urea groups if urea groups are present), the urethane group concentration of the polyurethane resin (U2) (the total concentration of urethane groups and urea groups if urea groups are present), and the crosslinking point concentration of the polyurethane resin (U2).

[0100] In the present invention, the indentation creep rate from the surface layer (CIT) is measured by the following method. <Method for measuring indentation creep rate from the surface layer (CIT)> (1) Place the multilayer film on the temperature-controlled stage of the device and control the temperature at 25°C or -10°C for 5 minutes. (2) Use a Berkovich indenter to apply a load of 10 μN to the surface layer side of the multilayer film for 10 seconds, and define the displacement as h1. (3) Define the displacement after maintaining the 10 μN load for 10 seconds as h2, and use the following formula to determine the indentation creep rate from the surface layer (CIT). Indentation creep rate from the surface layer (CIT) (%) = {(h2 - h1) / h1} × 100

[0101] From the viewpoint of abrasion resistance, the multilayer film of the present invention preferably has an elastic recovery rate at 100% elongation of 80 to 100%, more preferably 85 to 100%. If the elastic recovery rate at 100% elongation of the multilayer film is less than 80%, the abrasion resistance will be deteriorated. The elastic recovery rate at 100% elongation of the multilayer film can be adjusted by the urethane group concentration of the polyurethane resin (U1) (if urea groups are present, the total concentration of urethane groups and urea groups), the urethane group concentration of the polyurethane resin (U2) (if urea groups are present, the total concentration of urethane groups and urea groups), and the crosslinking point concentration of the polyurethane resin (U2).

[0102] The elastic recovery rate in the present invention is measured by the following method. <Method for measuring elastic recovery rate> (1) A multilayer film is cut into a strip of 100 mm long x 5 mm wide x 400 μm thick, and a mark is made 25 mm from both ends of the long side to prepare a test piece. (2) After leaving this test piece at 23°C for 24 hours, the multilayer film is stretched using an Instron tensile tester with a chuck distance of 50 mm and a pulling rate of 300 mm / min until the gauge distance becomes 100 mm (stretching process), and then the chuck distance is returned to 50 mm (returning process). (3) The stress at 50% elongation in the elongation process is defined as M1, and the stress at 50% elongation in the return process is defined as M2, and the elastic recovery rate is calculated using the following formula: Elastic recovery rate (%) = (M2 / M1) x 100

[0103] <Method for producing a multilayer film> The method for producing the multilayer film of the present invention is not particularly limited, and can be produced, for example, by the following method. (1) Production process of a urethane prepolymer for a polyurethane resin (U1) used in the surface layer A compound (a1) having a polyorganosiloxane group and an active hydrogen group, a polymer polyol (a2), a chain extender (a3), and an isocyanate component (B1) are reacted in an organic solvent, if necessary, and then a reaction terminator (a4) is reacted to produce a urethane prepolymer for a polyurethane resin (U1) having a hydroxyl group at the terminal. (2) Production process of a urethane prepolymer for a polyurethane resin (U2) used in the base layer A polymer polyol (a2) and an isocyanate component (B2) are reacted in an organic solvent, if necessary, to produce a urethane prepolymer for a polyurethane resin (U2) having an isocyanate group at the terminal. (3) Surface Layer Formation Step A urethane prepolymer for polyurethane resin (U1) or an organic solvent solution thereof is mixed with a modified organic polyisocyanate (b5), and optionally inorganic particles (C) and additives (D), and the mixture is coated onto a release film to a predetermined film thickness. When an organic solvent is used, the organic solvent is dried. (4) Substrate Layer Formation Step A urethane prepolymer for polyurethane resin (U2) or an organic solvent solution thereof is mixed with a polymer polyol (a2) and / or a chain extender (a3), and the mixture is coated onto the surface layer obtained in (3) to a predetermined film thickness and cured by heating to form a substrate layer. When an organic solvent is used, drying is performed along with curing. By the above steps (1) to (4), a multilayer film having a surface layer and a substrate layer is formed on a release film.

[0104] The reaction temperature in the urethane prepolymer production process in steps (1) and (2) above is not particularly limited, but is preferably 50 to 140°C, more preferably 70 to 100°C. The reaction time is not particularly limited, but is preferably 1 to 10 hours, more preferably 2 to 8 hours.

[0105] The drying temperature in the above step (3) is not particularly limited, but is preferably 30 to 120°C, more preferably 40 to 100°C, and the drying time is not particularly limited, but is preferably 10 seconds to 5 minutes, more preferably 20 to 60 seconds. The curing temperature in the above step (4) is not particularly limited, but is preferably 60 to 150°C, more preferably 80 to 140°C, and the curing time is not particularly limited, but is preferably 1 to 8 hours, more preferably 2 to 6 hours. The drying of the organic solvent in the above step (4), which is performed as needed, is performed together with the above curing.

[0106] The multilayer film of the present invention is suitable as a surface protection film for optical members, and is particularly suitable as a surface protection film for flexible displays.

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, "parts" means "parts by weight."

[0108] <Production Example 1> [Production of urethane prepolymer for polyurethane resin (U1-1) used in surface layer] The types and amounts (parts by weight) of polyorganosiloxane groups and active hydrogen groups shown in Table 1 in a container equipped with a stirrer and a temperature controller were used. 1.4 parts of BY-16-853U as the compound (a1), 1.9 parts of KF-8012, 20.3 parts of UHC50-100 as the polymer polyol (a2), 50.8 parts of UHC40-200, 1.2 parts of 1,4-BG as the chain extender (a3) ​​and 0.16 parts of water, 18.3 parts of Millionate MT as the aromatic polyisocyanate (b1) having 8 to 26 carbon atoms, and 400.0 parts of toluene as an organic solvent were charged and reacted at 80 ° C. for 3 hours. Then, 0.39 parts of diethanolamine as the reaction terminator (a4) was charged and reacted at 80 ° C. for 1 hour to obtain a urethane prepolymer for the polyurethane resin (U1-1) used in the surface layer. The hydroxyl value of the obtained urethane prepolymer for polyurethane resin (U1-1) used for the surface layer was 0.78 KOHmg / g.

[0109] <Production Examples 2 to 6 and Comparative Production Examples 1 to 3> [Production of urethane prepolymers for polyurethane resins (U1-2) to (U1-6) used in surface layer and urethane prepolymers for comparative polyurethane resins (U1'-1) to (U1'-3)] Urethane prepolymers for polyurethane resins (U1-2) to (U1-6) used in the surface layer and urethane prepolymers for comparative polyurethane resins (U1'-1) to (U1'-3) were obtained in the same manner as in Production Example 1, except that the raw materials used and their amounts (parts by weight) were changed to those shown in Table 1. In Table 1, the compositions are rounded to one or two decimal places, so even if the values ​​in Table 1 are added up, the total of the (U1) constituent components may not add up to 100.0 parts.

[0110]

[0111] Production Example 7 Production of urethane prepolymer for polyurethane resin (U2-1) used in base layer A vessel equipped with a stirrer and temperature controller was charged with 48.9 parts of PTMG-2000 as the polymer polyol (a2), 25.4 parts of PTMG-1000 as the polymer polyol (a2), and 16.2 parts of Duranate 50M as the aliphatic isocyanate (b2) having 4 to 22 carbon atoms, in the types and amounts (parts by weight) shown in Table 2, and the mixture was reacted at 80°C for 3 hours to obtain a urethane prepolymer for polyurethane resin (U2-1). The NCO content of the obtained urethane prepolymer for polyurethane resin (U2-1) was 4.04%.

[0112] <Production Examples 8 to 12 and Comparative Production Examples 4 and 5> [Production of urethane prepolymers for polyurethane resins (U2-2) to (U2-6) used in base layer and urethane prepolymers for comparative polyurethane resins (U2'-1) to (U2'-2)] Urethane prepolymers for polyurethane resins (U2-2) to (U2-6) used in the base layer and urethane prepolymers for comparative polyurethane resins (U2'-1) to (U2'-2) were obtained in the same manner as in Production Example 7, except that the raw materials used and their amounts (parts by weight) were changed to those shown in Table 2.

[0113]

[0114] Example 1 Production of multilayer film 494.5 parts of the urethane prepolymer for polyurethane resin (U1-1) for the surface layer obtained in Production Example 1, 5.5 parts of CORONATE-2793 as the modified product (b5) of organic polyisocyanate described in Table 1 (a total of 500.0 parts of the urethane prepolymer for polyurethane resin (U1-1) and the modified product (b5) of organic polyisocyanate) and 250.2 parts of inorganic particle 1 dispersion as inorganic particles (C) described in Table 3, 0.25 parts of Irganox 245 as additive (D), 0.37 parts of Tinuvin 144, and 0.62 parts of Tinuvin 329 were mixed and coated on a release film so that the film thickness after drying was 2.5 μm, and the mixture was dried for 30 seconds in a circulating air dryer at 50 ° C. to volatilize the organic solvent to produce a polyurethane resin (U1-1) for the surface layer. 90.5 parts of the urethane prepolymer for polyurethane resin (U2-1) obtained in Production Example 7 and 8.9 parts of Sannix SP-750 as the polymer polyol (a2) described in Table 2, 0.60 parts of 1,4-BG as the chain extender (a3) ​​(a total of 100.0 parts of the urethane prepolymer for polyurethane resin (U2-1) and the polymer polyol (a2-2) and the chain extender (a3)), and 0.20 parts of Irganox 245 as the additive (D) described in Table 3, 0.30 parts of Tinuvin 144, and 0.50 parts of Tinuvin 329 were blended, and the film was coated on the polyurethane resin for the surface layer to a thickness of 400 μm, and cured at 120 ° C. for 2 hours, and the release film was peeled off to obtain a multilayer film in which the surface layer is polyurethane resin (U1-1) and the base layer is polyurethane resin (U2-1).

[0115] <Examples 2 to 21 and Comparative Examples 1 to 5> The multilayer films of Examples 2 to 21 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that the polyurethane resin (U1), inorganic particles (C), and additive (D) for the surface layer and the polyurethane resin (U2) and additive (D) for the base layer were changed to the combinations shown in Tables 3 and 4.

[0116] The details of the various raw materials listed in Tables 1 to 4 are as follows: [Compounds (a1) having a polyorganosiloxane group and an active hydrogen group] BY-16-853U: Amino-modified silicone oil manufactured by DuPont-Toray Specialty Materials Co., Ltd. [Mn = 900, R1 to R6 in general formula (1) = methyl groups, n = 10] KF-8012: Amino-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd. [Mn = 2,200, R1 to R6 in general formula (1) = methyl groups, n = 57] [High polymer polyols (a2)] UHC50-100: Polyester carbonate polyol manufactured by UBE Corporation, Mn = 1,000 UHC40-200: Polyester carbonate polyol manufactured by UBE Corporation, Mn = 2,000 T5651: Duranol T5651, polycarbonate polyol, Mn = 1,000, manufactured by Asahi Kasei Corporation. T5652: Duranol T5652, polycarbonate polyol, Mn = 2,000, manufactured by Asahi Kasei Corporation. PTMG-3000: polytetramethylene ether glycol, Mn = 3,000, manufactured by Mitsubishi Chemical Corporation. PTMG-2000: polytetramethylene ether glycol, Mn = 2,000, manufactured by Mitsubishi Chemical Corporation. PTMG-1000: polytetramethylene ether glycol, Mn = 1,000, manufactured by Mitsubishi Chemical Corporation. PLACCEL L220AL: polycaprolactone polyol, Mn = 2,000, manufactured by Daicel Corporation (PLACCEL is a registered trademark of Daicel Corporation). PLACCEL L212AL: Polycaprolactone polyol, Mn=2,000, manufactured by Daicel Corporation (PLACCEL is a registered trademark of Daicel Corporation) SANNICS SP-750: Polyoxypropylene sorbitol ether, Mn=700, manufactured by Sanyo Chemical Industries, Ltd. (SANNICS is a registered trademark of Sanyo Chemical Industries, Ltd.) [Chain extender (a3)] 1,4-BG: 1,4-BG manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.4-butanediol, trimethylolpropane: manufactured by Mitsubishi Gas Chemical Company, Inc. [reaction terminator (a4)], diethanolamine: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. [aromatic polyisocyanate (b1) having 8 to 26 carbon atoms], Millionate MT: MDI manufactured by Tosoh Corporation [aromatic polyisocyanate (b2) having 4 to 22 carbon atoms], Duranate 50M: HDI manufactured by Asahi Kasei Corporation (Duranate is a registered trademark of Asahi Kasei Corporation) [alicyclic isocyanate (b3) having 8 to 18 carbon atoms], Desmodur W: hydrogenated MDI manufactured by Sumika Covestro Urethane Co., Ltd. (Desmodur is a registered trademark of Covestro Intellectual Property GmbH) [modified organic polyisocyanate (b5)] CORONATE-2793: Allophanate group-containing polyisocyanate (average functionality = 5.1) manufactured by Tosoh Corporation [Inorganic particles (C)] Inorganic particle 1 dispersion: Organosilica sol, volume average particle diameter 12 nm, solid content 40 wt% ethyl methyl ketone dispersion Inorganic particle 2 dispersion: Organosilica sol, volume average particle diameter 45 nm, solid content 40 wt% ethyl methyl ketone dispersion Inorganic particle 3 dispersion: Organosilica sol, volume average particle diameter 80 nm, solid content 40 wt% ethyl methyl ketone dispersion Inorganic particle 4 dispersion: Zirconia, volume average particle diameter 10 nm, solid content 40 wt% ethyl methyl ketone dispersion [Additives (D)] Irganox 245: Hindered phenol-based antioxidant manufactured by BASF Japan Ltd. (Irganox is a registered trademark of BASF Societas Europea) Tinuvin 144: a hindered amine-based light stabilizer manufactured by BASF Japan Ltd. (Tinuvin is a registered trademark of BASF Societas Europea) Tinuvin 329: a benzotriazole-based ultraviolet absorber manufactured by BASF Japan Ltd. (Tinuvin is a registered trademark of BASF Societas Europea) [Organic solvents] Toluene,

[0117] [Method for evaluating the dynamic friction coefficient of the surface layer and the base layer] The dynamic friction coefficient of the surface layer and the base layer of the multilayer film was measured according to the procedure described above. The thickness of the multilayer film was adjusted to 400 μm by adjusting the thickness of the base layer. The results are shown in Tables 3 and 4. The slipperiness of the surface of the multilayer film was evaluated by the dynamic friction coefficient of the surface layer side.

[0118] [Method for evaluating the indentation creep rate (CIT) from the surface layer at 25°C] (1) The multilayer film was placed on the temperature-controlled stage of the measuring device and the temperature was controlled at 25°C for 5 minutes. (2) A load of 10 μN was applied to the surface layer of the multilayer film obtained in the Examples and Comparative Examples using a Berkovich indenter for 10 seconds, and the displacement after that was taken as h1. (3) The displacement after maintaining the 10 μN load for 10 seconds was taken as h2, and the indentation creep rate (CIT) was calculated using the following formula. The results are shown in Tables 3 and 4. Indentation creep rate (CIT) (%) = {(h2 - h1) / h1} x 100

[0119] [Method for evaluating the indentation creep rate (CIT) from the surface layer at -10°C] (1) The multilayer film was placed on the temperature-controlled stage of the measuring device and the temperature was controlled at -10°C for 5 minutes. (2) A load of 10 μN was applied to the surface layer of the multilayer film obtained in the Examples and Comparative Examples using a Berkovich indenter for 10 seconds, and the displacement after that was taken as h1. (3) The displacement after maintaining the 10 μN load for 10 seconds was taken as h2, and the indentation creep rate (CIT) was calculated using the following formula. The results are shown in Tables 3 and 4. Indentation creep rate (CIT) (%) = {(h2 - h1) / h1} x 100

[0120] [Method for evaluating elastic recovery rate] (1) The multilayer film obtained in the examples and comparative examples was cut into a strip measuring 100 mm in length, 5 mm in width, and 400 μm in thickness. A mark was placed 25 mm from both ends of the long side to prepare a test piece. (2) After leaving this test piece at 23 ° C. for 24 hours, the multilayer film was stretched using an Instron tensile tester with a chuck distance of 50 mm and a pulling speed of 300 mm / min until the gauge distance reached 100 mm (stretching process), and then the chuck distance was returned to 50 mm (returning process). (3) The stress at 50% elongation during the elongation process was defined as M1, and the stress at 50% elongation during the return process was defined as M2, and the following formula was used to calculate the elastic recovery rate. The results are shown in Tables 3 and 4. Elastic recovery rate (%) = (M2 / M1) × 100

[0121] [Method for evaluating scratch resistance] Steel wool (No. 0000) manufactured by Nippon Steel Wool Co., Ltd. was attached to a steel wool fixing jig of "Tribogear Type: 40 (Tribogear is a registered trademark of Shinto Scientific Co., Ltd.)" manufactured by Shinto Scientific Co., Ltd., and the steel wool was cut to a thickness of 1 cm. ２ The surface layer side of the multilayer films obtained in the Examples and Comparative Examples was rubbed repeatedly over a length of 5 cm with a load of 100 g per stroke, and the number of strokes required for scratches to occur was observed and evaluated based on the following criteria. The results are shown in Tables 3 and 4. <Evaluation criteria> ⊚: No scratches occurred after 500 strokes or more. ○: Scratches occurred after 300 to less than 500 strokes. ×: Scratches occurred after less than 300 strokes.

[0122] [Method for evaluating flex resistance] For the multilayer films obtained in the examples and comparative examples, samples measuring 50 mm in the width direction (direction of the folded portion) x 100 mm in the machine direction (bending direction) were prepared. Using a no-load U-shaped stretch tester (Yuasa System Co., Ltd., DLDMLH-FS), a bending radius of 3 mm was set and the sample was bent 50,000 times at a speed of 1 time / second. At this time, the sample was fixed at positions 10 mm from both ends of the long side, and the bending area was 50 mm x 80 mm. After the bending process was completed, the sample was placed on a flat surface with the inside of the bend facing down and visually inspected. The results are shown in Tables 3 and 4. <Evaluation criteria> ◎: No deformation of the sample, or even if there was deformation, the maximum lift height when placed horizontally was less than 3 mm. ○: There was deformation of the sample, and when placed horizontally, the maximum lift height was 3 mm or more but less than 5 mm. ×: There was a fold mark on the sample, or when placed horizontally, the maximum lift height was 5 mm or more.

[0123] [Method for evaluating total light transmittance and haze] The total light transmittance and haze values ​​of the multilayer films obtained in the examples and comparative examples were measured using a spectrophotometer (manufactured by Konica Minolta, Inc., product name "CM3600A"). The results are shown in Tables 3 and 4.

[0124] [Method for evaluating flexibility at low temperatures] (1) A multilayer film cut into a strip measuring 50 mm in length, 15 mm in width, and 400 μm in thickness was wrapped around a glass rod with a diameter of 10 mm and fixed. (2) This test piece was left to stand at -20°C for 24 hours. (3) After 24 hours, the multilayer film was removed from the glass rod, and while kept at -20°C, it was placed on a flat surface with the bent inside facing down and visually inspected. The results are shown in Tables 3 and 4. <Evaluation criteria> ⊚: No deformation of the sample, or even if there was deformation, the maximum lift height when placed horizontally was less than 3 mm. ○: There was deformation of the sample, and when placed horizontally, the maximum lift height was 3 mm or more but less than 5 mm. ×: There was deformation of the sample, and when placed horizontally, the maximum lift height was 5 mm or more.

[0125]

[0126]

[0127] The multilayer film of the present invention has excellent flexibility at low temperatures, excellent surface slipperiness, and excellent scratch resistance and flex resistance, and is therefore suitable as a surface protection film for optical components such as flexible displays.

Claims

1. A multilayer film having at least a base layer and a surface layer, wherein the surface layer has a dynamic friction coefficient of 0.4 to 1.2 measured under the following conditions, the surface layer contains a polyurethane resin (U1) obtained by reacting an active hydrogen component (A1) containing, as an essential component, a compound (a1) having a polyorganosiloxane group and an active hydrogen group with an isocyanate component (B1), and the polyurethane resin (U1) has a urethane group concentration (when urea groups are present, the total concentration of urethane groups and urea groups) of 1.0 to 1.8 mmol / g, the base layer has a dynamic friction coefficient of greater than 1.2 measured under the following conditions, the base layer contains a polyurethane resin (U2) obtained by reacting an active hydrogen component (A2) with an isocyanate component (B2), and the polyurethane resin (U2) has a urethane group concentration (when urea groups are present, the total concentration of urethane groups and urea groups) of 1.0 to 2.0 mmol / g, A multilayer film in which the crosslinking point concentration of the polyurethane resin (U2) is 0.1 to 0.50 mmol / g as calculated by the following formula (1): <Method for measuring the dynamic friction coefficient> (1) A multilayer film cut into a rectangle measuring 100 mm in length, 50 mm in width, and 400 μm in thickness is fixed on a glass plate with the layer to be measured facing up. (2) After leaving the multilayer film at 23°C for 24 hours, the dynamic friction coefficient is measured using a Tribomaster TL201s and a tactile contactor manufactured by Trinity Labs, Inc., under the following conditions: temperature 23°C, load 30 gf, speed 50 mm / s, and travel distance 50 mm. <Method for calculating the crosslinking point concentration> Crosslinking point concentration of polyurethane resin (mmol / g) = (F-2) × (number of millimoles of tri- or higher functional monomers in 1 g of polyurethane resin) (1) 2. The multilayer film according to claim 1, wherein the surface layer contains inorganic particles (C).

3. The multilayer film according to claim 1, wherein the elastic recovery at 100% elongation measured under the following conditions is 80 to 100%. <Method for measuring elastic recovery> (1) A test piece is prepared by cutting a multilayer film into a strip measuring 100 mm in length, 5 mm in width, and 400 μm in thickness, and marking a mark 25 mm from each end of the long side. (2) After leaving this test piece at 23°C for 24 hours, the multilayer film is stretched in an Instron tensile tester at a chuck distance of 50 mm and a pulling rate of 300 mm / min until the gauge distance reaches 100 mm (elongation process), and then the chuck distance is returned to 50 mm (return process). (3) The stress at 50% elongation in the elongation process is defined as M1, and the stress at 50% elongation in the return process is defined as M2, and the elastic recovery is calculated using the following formula: Elastic recovery (%) = (M2 / M1) x 100 4. The multilayer film according to claim 1, wherein the polyorganosiloxane group is a polyorganosiloxane group represented by the following general formula (1): [In the formula, R １ ~R ６ each independently represents a hydrocarbon group having 1 to 6 carbon atoms, and n is an integer of 1 to 100.

5. A multilayer film according to any one of claims 1 to 4, wherein the weight of the compound (a1) having a polyorganosiloxane group and an active hydrogen group is 0.5 to 5% by weight, based on the weight of the polyurethane resin (U1), as a constituent component.

6. The multilayer film according to any one of claims 1 to 4, wherein the crosslinking point concentration of the polyurethane resin (U1) calculated by the following formula (1) is 0.01 to 0.20 mmol / g: Crosslinking point concentration of polyurethane resin (mmol / g) = (F - 2) x (number of millimoles of tri- or higher functional constituent monomers per 1 g of polyurethane resin) (1) (In formula (1), F represents the number of functional groups of the tri- or higher functional constituent monomers.) 7. The multilayer film according to claim 5, wherein the crosslinking point concentration of the polyurethane resin (U1) calculated by the following formula (1) is 0.01 to 0.20 mmol / g: Crosslinking point concentration of polyurethane resin (mmol / g) = (F - 2) × (number of millimoles of tri- or higher functional monomers per 1 g of polyurethane resin) (1) (In formula (1), F represents the number of functional groups of the tri- or higher functional monomers.) 8. The multilayer film according to any one of claims 1 to 4, which is used as a surface protection film for optical components.

9. The multilayer film according to claim 5, which is used as a surface protection film for optical components.

10. The multilayer film according to claim 6, which is used as a surface protection film for optical components.

11. The multilayer film according to claim 7, which is used as a surface protection film for optical components.

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