CN114040848A

CN114040848A - Multilayer film

Info

Publication number: CN114040848A
Application number: CN202080046810.4A
Authority: CN
Inventors: 泽田雅史; 柳田正毅
Original assignee: Sanyo Chemical Industries Ltd
Current assignee: Sanyo Chemical Industries Ltd
Priority date: 2019-07-02
Filing date: 2020-06-30
Publication date: 2022-02-11
Also published as: WO2021002342A1; JPWO2021002342A1; JP7142167B2; KR20210144781A

Abstract

The invention provides a film which is excellent in scratch resistance and flexing resistance. The present invention relates to a multilayer film having a base layer and a surface layer formed on the base layer, wherein the surface layer contains a urethane resin (U1) composed of an active hydrogen component (A1) and an isocyanate component (B1), the active hydrogen component (A1) contains a compound (a1) having a polyorganosiloxane group and an active hydrogen group as essential components, and the urethane resin (U1) has an elastic recovery of 50 to 100% at 100% elongation; the base layer contains a urethane resin (U2) comprising an active hydrogen component (A2) and an isocyanate component (B2), the active hydrogen component (A2) is an active hydrogen component containing not the compound (a1) having the polyorganosiloxane group and the active hydrogen group but containing a polymer polyol (a2) as an essential component, and the urethane resin (U2) has an elastic recovery rate of 80 to 100% at 100% elongation.

Description

Multilayer film

Technical Field

The present invention relates to a multilayer film.

Background

Conventionally, a hard-coated film has been used as a surface protective film for an optical member such as a liquid crystal panel. However, although the film can be made less susceptible to damage by increasing the surface hardness of the film, once damaged, the damage cannot be recovered.

Therefore, studies have been made on materials having self-repairability, and for example, a film obtained by laminating a polyester urethane resin on a transparent substrate such as polyamide, polycarbonate, or polyimide has been proposed (for example, see patent document 1).

However, the conventional techniques including the multilayer film described in patent document 1 have a problem that the scratch recovery time is long and the scratch resistance is insufficient under conditions where fine scratches are easily formed. In addition, the conventional techniques have a problem of insufficient flexure resistance.

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication No. 2019-511386

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a film having excellent scratch resistance and excellent flexing resistance.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have reached the present invention.

That is, the present invention relates to a multilayer film having a base layer and a surface layer formed on the base layer, wherein the surface layer contains a urethane resin (U1) composed of an active hydrogen component (a1) and an isocyanate component (B1), the active hydrogen component (a1) contains a compound (a1) having a polyorganosiloxane group and an active hydrogen group as essential components, and the urethane resin (U1) has an elastic recovery of 50 to 100% at 100% elongation; the base layer contains a urethane resin (U2) comprising an active hydrogen component (A2) and an isocyanate component (B2), the active hydrogen component (A2) is an active hydrogen component containing not a compound (a1) having a polyorganosiloxane group and an active hydrogen group but containing a polymer polyol (a2) as an essential component, and the urethane resin (U2) has an elastic recovery rate of 80 to 100% at 100% elongation.

ADVANTAGEOUS EFFECTS OF INVENTION

The multilayer film of the present invention is excellent in scratch resistance and also excellent in flex resistance.

Detailed Description

The multilayer film of the present invention is a multilayer film having a base layer and a surface layer formed on the base layer.

The surface layer contains a polyurethane resin (U1) comprising an active hydrogen component (A1) and an isocyanate component (B1), the active hydrogen component (A1) contains a compound (a1) having a polyorganosiloxane group and an active hydrogen group as essential components, the polyurethane resin (U1) has an elastic recovery of 50 to 100% at 100% elongation, the base layer contains a polyurethane resin (U2) comprising an active hydrogen component (A2) and an isocyanate component (B2), the active hydrogen component (A2) is an active hydrogen component containing no compound (a1) having the polyorganosiloxane group and the active hydrogen group and containing a polymer polyol (a2) as essential components, and the polyurethane resin (U2) has an elastic recovery of 80 to 100% at 100% elongation.

The polyurethane resin (U1) composed of an active hydrogen component (A1) and an isocyanate component (B1) is contained in the surface layer, the active hydrogen component (A1) contains a compound (a1) having a polyorganosiloxane group and an active hydrogen group as an essential component, and the polyurethane resin (U1) has an elastic recovery of 50 to 100% at 100% elongation, thereby improving scratch resistance.

Further, by incorporating a urethane resin (U2) comprising an active hydrogen component (a2) and an isocyanate component (B2) into the base layer, wherein the active hydrogen component (a2) is an active hydrogen component containing not the compound (a1) having the polyorganosiloxane group and the active hydrogen group but a polymer polyol (a2) as an essential component, the urethane resin (U2) has an elastic recovery rate of 80 to 100% at 100% elongation, and thus a film having excellent scratch resistance and flexing resistance can be obtained.

In addition, although the urethane resin (U2) used for the base layer in the present invention is generally excellent in scratch resistance and flex resistance, the surface often becomes sticky, and the provision of the surface layer in the present invention can suppress the generation of stickiness on the surface of the multilayer film.

[ surface layer ]

The urethane resin (U1) which is the main constituent component of the surface layer is a urethane resin obtained by reacting an active hydrogen component (a1) with an isocyanate component (B1), and the active hydrogen component (a1) contains a compound (a1) having a polyorganosiloxane group and an active hydrogen group as an essential component.

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 essential components, and a polymer polyol (a2), a chain extender (A3), and a reaction terminator (a4) as optional components.

The compound (a1) having a polyorganosiloxane group and an active hydrogen group is preferably a compound having a polyorganosiloxane group represented by the general formula (1) in view of scratch resistance and haze.

[ solution 1]

R in the general formula (1)¹～R⁶Each independently represents a hydrocarbon group having 1 to 6 carbon atoms. As R¹～R⁶From the viewpoint of scratch resistance, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is more preferable.

N in the general formula (1) is an integer of 1 to 100, and is preferably 10 to 70, more preferably 15 to 50, from the viewpoint of scratch resistance and haze.

Examples of the active hydrogen group of the compound (a1) [ hereinafter abbreviated as (a1) ] having a polyorganosiloxane group and an active hydrogen group include a hydroxyl group, an amino group, and a carboxyl group.

(a1) The compatibility with other constituent monomers of the urethane resin (U1) is generally low, and from the viewpoint of uniformly introducing (a1) into the urethane resin (U1) and suppressing the increase in haze of (U1), it is preferable to use (a1) having a hydroxyl group and an amino group as the active hydrogen group. (a1) The number of the compounds may be 1 or more than 2.

(a1) Among the compounds having a hydroxyl group (a11), commercially available compounds can be used, and examples thereof include "KF-6001" (functional group equivalent 900g/mol), "KF-6002" (functional group equivalent 1600g/mol), "KF-6003" (functional group equivalent 2550g/mol) having a hydroxyl group at both terminals, "X-22-1821" (functional group equivalent 1470g/mol) (manufactured BY shin-Chemie Co., Ltd.), and "BY-16-752A" (functional group equivalent 1500g/mol) (manufactured BY Toray-Dow Corning Co., Ltd.), and "X-22-170 BX" (functional group equivalent 2800g/mol) and "X-22-DX 170" (functional group equivalent 4670g/mol) having a hydroxyl group at one terminal, "X-22-176 DX" (functional group equivalent 1600g/mol), "X-22-176F" (functional group equivalent 6300g/mol) (manufactured by shin-Etsu chemical Co., Ltd.), "X-22-4039" (functional group equivalent 970g/mol) having a hydroxyl group in a side chain, "X-22-4015" (functional group equivalent 1870g/mol) (manufactured by shin-Etsu chemical Co., Ltd.), and "SF 8427" (functional group equivalent 930g/mol, manufactured by Toray-Dow Corning Co., Ltd.) having a hydroxyl group in a polyether at both ends and "X-22-4952" (functional group equivalent 1100g/mol, manufactured by shin-Etsu chemical Co., Ltd.); "FZ-2162" (functional equivalent of 750) and "SH 3773M" (functional equivalent of 800g/mol) each having a hydroxyl group in a branched polyether (these are manufactured by Toray-Dow Corning Co., Ltd.).

(a1) Among the compounds having an amino group (a12), commercially available compounds can be used, and examples thereof include "KF-8010" (functional group equivalent 430g/mol), "X-22-161A" (functional group equivalent 800g/mol), "X-22-161B" (functional group equivalent 1500g/mol), "KF-8012" (functional group equivalent 2200g/mol), "KF-8008" (functional group equivalent 5700g/mol), "X-22-9409" (functional group equivalent 700g/mol), "X-22-1660B-3" (functional group equivalent 2200g/mol) (manufactured BY shin-Etsu chemical Co., Ltd.), "BY-16-853U" (functional group equivalent 460g/mol), "BY-16-853" (functional group equivalent 650g/mol), and the like, each having an amino group at both ends, "BY-16-853B" (2200 g/mol in functional group equivalent) (manufactured BY Toray-Dow Corning Co., Ltd.) and "KF-868" (8800 g/mol in functional group equivalent), KF-865 "(5000 g/mol in functional group equivalent), KF-864" (3800 in functional group equivalent), KF-880 "(1800 g/mol in functional group equivalent) and KF-8004" (1500 g/mol in functional group equivalent) (manufactured BY shin-Etsu chemical Co., Ltd.) have amino groups in their branched chains.

(a1) Among them, as the compound having a carboxyl group (a13), commercially available products can be used, and examples thereof include "X-22-162C" having carboxyl groups at both terminals (functional group equivalent 2300g/mol), "X-22-3710" having carboxyl groups at one terminal (functional group equivalent 1450g/mol), and "X-22-3701E" having carboxyl groups in a branch chain (functional group equivalent 4000g/mol) (manufactured by shin-Etsu chemical Co., Ltd.).

The weight 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, and more preferably 1 to 4% by weight, based on the weight of the polyurethane resin (U1), from the viewpoints of scratch resistance, tack-free property, and haze.

The polymer polyol (a2) is preferably a polymer polyol having a number average molecular weight (hereinafter abbreviated as Mn) of 500 or more, and specifically, polyester polyol (a21), polyether polyol (a22), polyether polyol (a23) and the like can be mentioned. The polymer polyol (a2) may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

Examples of the polyester polyol (a21) include a condensation type polyester polyol, a polylactone polyol, and a polycarbonate polyol.

Examples of the condensed polyester polyol include polyester polyols obtained by condensation of Mn or a polyhydric alcohol having a formula weight of less than 500 with a polycarboxylic acid having 2 to 20 carbon atoms or an ester-forming derivative thereof [ acid anhydride, lower (C1-C4) alkyl ester, acid halide, etc. ].

Examples of the polyol having Mn or a formula weight of less than 500 include polyols having 2 to 20 carbon atoms; alkylene oxide (hereinafter abbreviated as AO) adduct of 2 to 12 carbon atoms of a polyhydric alcohol having 2 to 20 carbon atoms and having Mn or a formula weight of less than 500; an AO adduct of bisphenol (bisphenol A, bisphenol S, bisphenol F, etc.) having 2 to 12 carbon atoms and having Mn or a formula weight of less than 500; bis (2-hydroxyethyl) terephthalate and an AO adduct thereof having 2 to 12 carbon atoms, wherein Mn or the formula weight is less than 500; and the like.

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

Examples of the polyhydric alcohol having 2 to 20 carbon atoms include linear or branched aliphatic diols having 2 to 12 carbon atoms [ e.g., linear alcohols such as ethylene glycol, 1, 3-propanediol, 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-butanediol, 1, 3-butanediol or 2, 3-butanediol, 2-methyl-1, 4-butanediol, neopentyl glycol, 2-diethyl-1, 3-propanediol, 2-methyl-1, 5-pentanediol, 3-methyl-1, 5-pentanediol, branched alcohols such as 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 diols having 6 to 20 carbon atoms [1, 4-cyclohexanediol, 1, 3-cyclohexanedimethanol, 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, 2-bis (4-hydroxycyclohexyl) propane, and the like ]; aromatic aliphatic diols having 8 to 20 carbon atoms [ e.g., m-xylene glycol, p-xylene glycol, bis (hydroxyethyl) benzene, and bis (hydroxyethoxy) benzene ]; trihydric alcohols having 3 to 20 carbon atoms [ aliphatic triols (such as glycerin and trimethylolpropane) ]; tetrahydric to octahydric alcohols having 5 to 20 carbon atoms [ aliphatic polyhydric alcohols (pentaerythritol, sorbitol, mannitol, sorbitan, diglycerol, dipentaerythritol, and the like); sugars (sucrose, glucose, mannose, fructose, methylglucoside and derivatives thereof) ]; and the like.

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' -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 (adipoyl chloride, etc.), low molecular weight alkyl esters thereof (dimethyl succinate, dimethyl phthalate, etc.), and combinations thereof.

Examples of the above-mentioned polylactone polyol include polylactone polyols obtained by ring-opening polymerization of lactone monomers having 3 to 12 carbon atoms (such as β -propiolactone, γ -butyrolactone, γ -valerolactone, e-caprolactone, η -caprolactone, 11-undecanolactone and 12-tridecane compounds) using the above-mentioned polyhydric alcohol having 2 to 20 carbon atoms as an initiator. The lactone monomers may be used alone in 1 kind, or in combination in 2 or more kinds.

The polycarbonate polyol is produced by condensing 1 or 2 or more (preferably 2 to 4) of the above-mentioned polyhydric alcohol having 2 to 20 carbon atoms (preferably an aliphatic diol having 3 to 9 carbon atoms, and more preferably 4 to 6 carbon atoms) with a low molecular carbonate compound (for example, a dialkyl carbonate having an alkyl group having 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 carrying out a dealcoholization reaction.

Examples of the polyether polyol (a22) include compounds obtained by adding AO having 2 to 12 carbon atoms to the above Mn or a polyol having a formula weight of less than 500. The AO may be used singly or in combination of 1 or more, and in the latter case, it may be a block addition (tip type), equilibrium type, active secondary type, or the like), a random addition, or a combination system thereof.

The addition of AO to the above Mn or polyol having a formula weight of less than 500 is carried out in one or more stages under normal pressure or under pressure, for example, in the absence of a catalyst or in the presence of a catalyst (a basic catalyst, an amine-based catalyst, an acid catalyst, or the like) (particularly, in the latter half of the addition of AO).

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

Examples of the polyetherester polyol (a23) include polyetherester polyols obtained by polycondensing 1 or more kinds of the above polyether polyols with 1 or more kinds of the above polycarboxylic acids having 2 to 20 carbon atoms or ester-forming derivatives thereof exemplified as the raw materials of the above condensed polyester polyols.

Among the high-molecular polyols (a2) in the polyurethane resin (U1), polycarbonate polyols are particularly preferred in terms of scratch resistance, non-tackiness, and chemical resistance.

From the viewpoint of scratch resistance, the Mn of the polymer polyol (a2) is preferably 500 or more, more preferably 500 to 5000, and particularly preferably 800 to 3000.

In the present invention, Mn of the polymer polyol (a2) can be measured by gel permeation chromatography under the following conditions, for example.

The device comprises the following steps: "Waters Alliance 2695" [ manufactured by Waters corporation ]

Column: "Guardcolumn SuperH-L" (1 root), "TSKgel SuperH2000, TSKgel SuperH3000, TSKgel SuperH4000 (all manufactured by Tosoh Corp.) each 1 column linked"

Sample solution: 0.25% by weight tetrahydrofuran solution

Solution injection amount: 10 μ l

Flow rate: 0.6 ml/min

Measuring temperature: 40 deg.C

The detection device comprises: refractive index detector

Reference substance: standard polyethylene glycol

From the viewpoint of scratch resistance and tack-free properties, the weight of the polymer 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.

Examples of the chain extender (a3) include water, the above-mentioned Mn or polyhydric alcohol having a formula weight of less than 500, and Mn or polyhydric amine compound having a formula weight of less than 500.

Examples of the polyol having Mn or a formula weight of less than 500 include those similar to those of the polyol having Mn or a formula weight of less than 500 constituting the condensed polyester polyol.

Examples of the polyamine compound having Mn or a formula weight of less than 500 include aliphatic polyamines having 2 to 36 carbon atoms [ alkylene diamines such as ethylenediamine and hexamethylenediamine; a poly (n-2-6) alkylene group (e.g., a 2-6 carbon poly (n-3-7) amine) such as diethylenetriamine, dipropylenetriamine, dihexylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine), an alicyclic polyamine having 6-20 carbon atoms (e.g., 1, 3-cyclohexanediamine or 1, 4-cyclohexanediamine, 4 '-dicyclohexylmethanediamine or 2, 4' -dicyclohexylmethanediamine, and isophoronediamine), an aromatic polyamine having 6-20 carbon atoms (e.g., 1, 3-phenylenediamine or 1, 4-phenylenediamine, 2, 4-toluenediamine or 2, 6-toluenediamine, 4 '-methylenedianiline or 2, 4' -methylenedianiline), an aromatic aliphatic polyamine having 8-20 carbon atoms [1, 3-xylylenediamine, 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 (a dibasic acid dihydrazide such as adipic acid dihydrazide, etc.), aminoalcohols having 2 to 20 carbon atoms (ethanolamine, diethanolamine, 2-amino-2-methylpropanol, triethanolamine, etc.), etc.

Among the chain extenders (a3), water, ethylene glycol, 1, 4-butanediol and trimethylolpropane are preferred from the viewpoint of scratch 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, from the viewpoints of scratch resistance and tack-free property.

Examples of the reaction terminator (a4) include monoalcohols having 1 to 20 carbon atoms (methanol, ethanol, butanol, octanol, decanol, dodecanol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and the like), monoamines having 1 to 20 carbon atoms (monoalkylamines or dialkylamines such as monomethylamine, monoethylamine, monobutylamine, dibutylamine, and monooctylamine, and monoalkanolamines or dialkanolamines such as monoethanolamine, diethanolamine, and diisopropanolamine, and the like).

Among the reaction terminators (a4), monoethanolamine and diethanolamine are preferred from the viewpoint of scratch resistance and tack-free property.

Examples of the polyisocyanate component (B1) include an aromatic polyisocyanate having 2 to 3 or more isocyanate groups and having 8 to 26 carbon atoms (B1), an aliphatic polyisocyanate having 4 to 22 carbon atoms (B2), an alicyclic polyisocyanate having 8 to 18 carbon atoms (B3), an araliphatic polyisocyanate having 10 to 18 carbon atoms (B4), and a modified product of these organic polyisocyanates (B5).

Examples of the aromatic polyisocyanate having 8 to 26 carbon atoms (b1) [ hereinafter abbreviated as (b1) ] include 1, 3-phenylene diisocyanate or 1, 4-phenylene diisocyanate, 2, 4-tolylene diisocyanate or 2, 6-tolylene diisocyanate (hereinafter abbreviated as TDI), crude TDI, 4 ' -diphenylmethane diisocyanate or 2,4 ' -diphenylmethane diisocyanate (hereinafter abbreviated as MDI), crude MDI, polyarylate polyisocyanate, 4 ' -diisocyanatobenzene, 3 ' -dimethyl-4, 4 ' -diisocyanatodiphenylmethane, and mixtures thereof, 1, 5-naphthalene diisocyanate, 4' -triphenylmethane triisocyanate and meta-or para-isocyanatobenzenesulfonyl isocyanate.

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

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

Examples of the aliphatic and aromatic polyisocyanate having 10 to 18 carbon atoms (b4) [ hereinafter abbreviated as (b4) ] include m-xylylene diisocyanate, p-xylylene diisocyanate and α, α, α ', α' -tetramethylxylylene diisocyanate.

Examples of the modified organic polyisocyanate (b5) of (b1) to (b4) include modified organic polyisocyanates having a urethane group, a carbodiimide group, an allophanate group, a urea group, a biuret group, a uretdione group, an uretonimine group, an isocyanurate group or an oxazolidone group [ for example, modified MDI (e.g., urethane-modified MDI, carbodiimide-modified MDI, trihydrocarbyl phosphate-modified MDI), urethane-modified TDI, biuret-modified HDI, isocyanurate-modified HDI and isocyanurate-modified IPDI ] of the above polyisocyanates.

Among the isocyanate components (B1) in the polyurethane resin (U1), the aromatic polyisocyanate (B1) having 8 to 26 carbon atoms is preferable, the aromatic diisocyanate having 8 to 26 carbon atoms is more preferable, and MDI is particularly preferable, from the viewpoint of scratch resistance.

The isocyanate component (B1) may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

From the viewpoint of scratch resistance and non-tackiness, the isocyanate component (B1) in the polyurethane resin (U1) is preferably 10 to 50% by weight, more preferably 20 to 40% by weight, based on the weight of the polyurethane resin (U1), as a constituent component.

The elastic recovery rate of the polyurethane resin (U1) can be set to a predetermined range by adjusting the glass transition point (Tg) of the polymer polyol (a2) used for the polyurethane resin (U1), the concentration of the crosslinking point in the polyurethane resin (U1), the concentration of the urethane group and the urea group in the polyurethane resin (U1), and the like.

The Tg of the polymer polyol (a2) used in the polyurethane resin (U1) is preferably-20 ℃ or lower, the concentration of the crosslinking point of the polyurethane resin (U1) is preferably 0.03 to 0.25mmol/g, and the concentration of the urethane group (the total concentration of the urethane group and the urea group when urea groups are present) in the polyurethane resin (U1) is preferably 1.5 to 2.5 mmol/g.

The concentration (unit: mmol/g) of the crosslinking point of the polyurethane resin (U1) in the present invention is a value calculated by calculating (F-2) × { millimoles of 3-or more-functional constituent monomers in 1g of the polyurethane resin (U2) for 3-or more-functional constituent monomers, respectively, and summing the calculated values, assuming that the number of functional groups of 3-or more-functional constituent monomers used in the polyurethane resin (U1) is F.

The method for producing the urethane resin (U1) in the present invention is not particularly limited, and examples thereof include: a method in which a urethane prepolymer is produced in advance using an active hydrogen component (a1), an isocyanate component (B1), and, if necessary, an organic solvent, and the urethane prepolymer is reacted with a chain extender; a method in which the active hydrogen component (a1), the isocyanate component (B1) and, if necessary, an organic solvent are charged into a batch reactor at once and heated to react; and the like.

The method for producing the urethane prepolymer is not particularly limited, and examples thereof include: a method in which the active hydrogen component (a1) and the isocyanate component (B1) are mixed in a kneader in the absence of a solvent and reacted by heating; a method in which an active hydrogen component (A1) and an isocyanate component (B1) are mixed in a batch reactor with a stirrer in the presence or absence of an organic solvent, and the mixture is heated to react.

In the method for producing the urethane resin (U1), an organic solvent may be used in any production step thereof. 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, diethylene glycol dimethyl ether, etc.), amide solvents having 3 to 10 carbon atoms (N, N-dimethylformamide, 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, isopropanol, octanol, etc.), hydrocarbon solvents having 4 to 10 carbon atoms (cyclohexane, methanol, ethanol, isopropanol, etc.), and the like, Toluene, xylene, etc.), and the like. The organic solvent may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

Among these, methyl ethyl ketone and toluene are preferable from the viewpoint of solubility.

When an organic solvent is used, the amount is preferably such that the concentration of the urethane resin (U1) is 10 to 70% by weight, and more preferably such that the concentration of the urethane resin (U1) is 15 to 50% by weight.

In addition, in the production of the urethane resin (U1), a catalyst may be contained as necessary in order to accelerate the reaction. Specific examples of the catalyst include organic metal compounds (dibutyltin dilaurate, dioctyltin dilaurate, bismuth carboxylates, bismuth alkoxides, chelate compounds of compounds having a dicarbonyl group and bismuth, and the like), inorganic metal compounds (bismuth oxide, bismuth hydroxide, bismuth halide, and the like); amines (triethylamine, triethylenediamine, 1, 8-diazabicyclo [5.4.0] -7-undecene, etc.) and combinations of 2 or more thereof.

The surface layer contains a urethane resin (U1) as an essential component, and may contain additives (D) such as an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, an adsorbent, a filler, a releasing agent, and a flame retardant, if necessary.

Examples of the antioxidant include hindered phenol compounds [ e.g., pentaerythrityl-tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], phosphorus compounds [ e.g., tris (2, 4-di-t-butylphenyl) phosphite ], sulfur compounds [ e.g., pentaerythrityl-tetrakis (3-laurylthiopropionate) and dilauryl-3, 3' -thiodipropionate ], and the like.

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

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

Examples of the plasticizer include phthalic acid esters (dibutyl phthalate, dioctyl phthalate, dibutyl benzyl phthalate, diisodecyl phthalate, etc.); aliphatic dibasic acid esters (di-2-ethylhexyl adipate, 2-ethylhexyl sebacate, etc.); trimellitates (tri-2-ethylhexyl trimellitate, trioctyl trimellitate, and the like); fatty acid esters (butyl oleate, etc.); aliphatic phosphoric acid esters (trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, tributoxyphosphate, etc.); aromatic phosphates [ e.g., triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, 2-ethylhexyl diphenyl phosphate, and tris (2, 6-dimethylphenyl) phosphate ]; halogenated aliphatic phosphate [ tris (chloroethyl) phosphate, tris (. beta. -chloropropyl) phosphate, tris (dichloropropyl) phosphate, tris (tribromoneopentyl) phosphate, etc. ]; and the like.

Examples of the adsorbent include alumina, silica gel, and a molecular sieve.

Examples of the filler include kaolin, talc, silica, titanium oxide, calcium carbonate, bentonite, mica, sericite, glass flake, glass fiber, graphite, magnesium hydroxide, aluminum hydroxide, antimony trioxide, barium sulfate, zinc borate, alumina, magnesium oxide, wollastonite, xonotlite, whisker, and metal powder.

As the releasing agent, known releasing agents can be used, and examples thereof include fluorine compound type releasing agents [ perfluoroalkyl (8 to 20 carbon atoms) phosphate (e.g., trifluoroperfluorooctyl phosphate and trifluoroperfluorododecyl phosphate) ]; silicone compound type release agents (dimethylpolysiloxane, amino-modified dimethylpolysiloxane, carboxyl-modified dimethylpolysiloxane, and the like); fatty acid ester type releasing agents [ e.g., a C10-24 fatty acid mono-or polyhydric alcohol ester (e.g., butyl stearate, hydrogenated castor oil, and ethylene glycol monostearate) ]; aliphatic amide-type releasing agents [ e.g., monoamides or bisamides of fatty acids having 8 to 24 carbon atoms (e.g., oleamide, palmitamide, and distearamide of ethylene diamine) ]; metal soaps (magnesium stearate, zinc stearate, etc.); natural or synthetic waxes (paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, and the like); and the like.

Examples of the flame retardant include halogen-containing flame retardants, phosphorus-containing flame retardants, antimony-containing flame retardants, metal hydroxide-containing flame retardants, and the like.

The polyurethane resin (U1) used for the surface layer has an elastic recovery rate of 50 to 100%, more preferably 60 to 100%, as measured by the method described later. When the elastic recovery of the polyurethane resin (U1) is less than 50%, the scratch resistance and the flexing resistance are poor.

By setting the configuration as described above, the urethane resin (U1) can be adjusted to a predetermined elastic recovery rate, and can be provided with scratch resistance and flexing resistance.

[ base layer ]

In the present invention, the base layer contains a urethane resin (U2) comprising an active hydrogen component (A2) and an isocyanate component (B2), the active hydrogen component (A2) is an active hydrogen component containing not a compound (a1) having a polyorganosiloxane group and an active hydrogen group but containing a polymer polyol (a2) as an essential component, and the urethane resin (U2) has an elastic recovery of 80 to 100% at 100% elongation.

The active hydrogen component (a2) in the polyurethane resin (U2) does not contain the compound (a1) having a polyorganosiloxane group and an active hydrogen group, and contains the polymer polyol (a2) as an essential component.

Since the urethane resin (U2) does not contain the compound (a1) having an active hydrogen group, it is excellent in transparency, and when the polymer polyol (a2) is contained as an essential component, it is possible to adjust a predetermined elastic recovery rate, and to impart scratch resistance and flexing resistance.

The compound (a1) having a polyorganosiloxane group and an active hydrogen group and the polymer polyol (a2) are the compound (a1) having a polyorganosiloxane group and an active hydrogen group and the polymer polyol (a2) described for the urethane resin (U1).

From the viewpoint of adjusting the elastic recovery to a predetermined range and appropriately imparting scratch resistance and flexing resistance, the polymer polyol (a2) preferably contains a polyether polyol (a22), more preferably contains polytetramethylene glycol, poly (oxy-3-methyltetramethylene) glycol and tetrahydrofuran/3-methyltetrahydrofuran copolymerized glycol, and particularly preferably contains polytetramethylene glycol.

From the viewpoint of scratch resistance, the Mn of the polymer polyol (a2) is preferably 500 or more, more preferably 500 to 5000, and particularly preferably 800 to 4000.

From the viewpoint of scratch resistance and flex resistance, the weight of the polymer polyol (a2) in the polyurethane resin (U2) is preferably 60 to 90% by weight, and more preferably 70 to 85% by weight, based on the weight of the polyurethane resin (U2), as a constituent component.

The active hydrogen component (a2) may contain a chain extender and a reaction terminator as optional components.

As the chain extender, the chain extender (a3) described in the urethane resin (U1) can be appropriately selected and used.

The reaction terminator (a4) described for the urethane resin (U1) can be appropriately selected and used.

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, from the viewpoints of scratch resistance and flex resistance.

As the polyisocyanate component (B2), the polyisocyanate component (B1) described in the urethane resin (U1) can be appropriately selected and used.

Among them, from the viewpoint of scratch resistance, an aromatic polyisocyanate (b1) having 8 to 26 carbon atoms is preferable, an aromatic diisocyanate having 8 to 26 carbon atoms is more preferable, and MDI is particularly preferable.

From the viewpoint of scratch resistance and flex resistance, the weight of the polyisocyanate 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.

The elastic recovery rate of the polyurethane resin (U2) can be set to a predetermined range by adjusting the glass transition point (Tg) of the polymer polyol (a2) used for the polyurethane resin (U2), the concentration of the crosslinking point in the polyurethane resin (U2), the concentration of the urethane group and the urea group in the polyurethane resin (U2), and the like.

The Tg of the polymer polyol (a2) used in the polyurethane resin (U2) is preferably-20 ℃ or lower, the concentration of the crosslinking point of the polyurethane resin (U2) is preferably 0.05 to 0.25mmol/g, and the concentration of the urethane group (the total concentration of the urethane group and the urea group when urea groups are present) in the polyurethane resin (U2) is preferably 1.0 to 2.0 mmol/g.

The concentration (unit: mmol/g) of the crosslinking point of the polyurethane resin (U2) in the present invention is a value calculated by calculating (F-2) × { millimoles number in 1g of the polyurethane resin (U2) of the constituent monomer having a functional group of 3 or more functions } for each of the constituent monomers having 3 or more functions, and summing up the results, where F is the number of functional groups of the constituent monomer having 3 or more functions used in the polyurethane resin (U2).

The method for producing the urethane resin (U2) in the present invention is not particularly limited, and the same method as the method for producing the urethane resin (U1) can be used except that the active hydrogen component (a2) and the isocyanate component (B2) are contained.

In addition, the catalyst used in the production method of the urethane resin (U1) may be contained as necessary in order to accelerate the reaction when the urethane resin (U2) is produced.

The base layer contains a urethane resin (U2) as an essential component, and may contain the above-mentioned additive (D) used in the production method of the urethane resin (U1) as needed.

The polyurethane resin (U2) used for the base layer has a function of quickly recovering the deformation of the multilayer film due to external pressure in the multilayer film of the present invention, and therefore the elastic recovery rate at 100% elongation needs to be 80 to 100%. The elastic recovery rate of the polyurethane resin (U2) is preferably 85 to 100%, more preferably 90 to 100%, and particularly preferably 95 to 100%. If the elastic recovery at 100% elongation is less than 80%, the scratch resistance and flexibility cannot be sufficiently imparted.

The elastic recovery at 100% elongation in the present invention is measured by the following method.

< method for measuring elastic recovery at 100% elongation >

(1) A long test piece having a length of 100 mm. times.5 mm was cut out from a sheet having a thickness of about 2mm, and a reticle was drawn so that the distance between the reticles was 50 mm.

(2) The test piece was set in a chuck of an INSTRON type tensile testing machine (Autograph manufactured by shimadzu corporation) and the following operations were performed: after elongation at a constant speed of 500 mm/min at 25 ℃ in an atmosphere to a distance between the marked lines of 100%, the distance between the chucks before elongation was immediately recovered at the same speed.

(3) The stress (M) at 50% elongation in the elongation at the time of this operation was measured₁) Stress at 50% elongation during recovery (M)₂) The elastic recovery rate was obtained from the following equation.

Elastic recovery (%) ═ M₂/M₁×100

[ multilayer film ]

The multilayer film of the present invention has a base layer and a skin layer formed on the base layer.

The film thickness of the surface layer is preferably 1 to 50 μm, more preferably 5 to 25, from the viewpoint of scratch resistance and suppression of tackiness.

The film thickness of the base layer is preferably 100 to 1000 μm, more preferably 300 to 600 μm, from the viewpoint of scratch resistance and flex resistance.

The multilayer film of the present invention is preferably used as a surface protective film for optical parts. In order to impart adhesiveness to the optical member, the base layer side may have an adhesive layer as necessary. As the adhesive layer, a known adhesive layer can be appropriately selected and used.

The method for producing the multilayer film of the present invention is not particularly limited, and the multilayer film can be produced by the following method, for example.

(1) Process for producing urethane prepolymer for polyurethane resin (U1) used for surface layer

A urethane prepolymer for a polyurethane resin (U1) having an isocyanate group at the end is produced by reacting a compound (a1) having a polyorganosiloxane group and an active hydrogen group, a high-molecular polyol (a2), and an isocyanate component (B1) in an organic solvent as required.

(2) Process for producing urethane prepolymer for polyurethane resin (U2) used for base layer

A urethane prepolymer for a polyurethane resin (U2) having an isocyanate group at the end is produced by reacting a high-molecular polyol (a2) and an isocyanate component (B2) in an organic solvent as required.

(3) Step of Forming surface layer

The urethane resin (U1) is mixed with the urethane prepolymer or its organic solvent solution, if necessary, with the polymer polyol (a2) and/or the chain extender (a3) and applied to the release film in a predetermined film thickness. When an organic solvent is used, the organic solvent is dried.

(4) Process for Forming base layer

The urethane resin (U2) is mixed with the chain extender (a3) using a urethane prepolymer or an organic solvent solution thereof, and the resulting surface layer is coated to a predetermined film thickness and cured by heating to form a base layer. In the case of using an organic solvent, the curing and the drying are performed simultaneously.

By the steps (1) to (4), a multilayer film having a surface layer and a base layer is formed on the release film.

The temperature of the urethane prepolymer reaction in the steps (1) and (2) is not particularly limited, but is preferably 50 to 140 ℃, more preferably 70 to 100 ℃, and the reaction time is not particularly limited, preferably 1 to 10 hours, more preferably 2 to 8 hours.

The drying temperature in the step (3) is not particularly limited, preferably 30 to 80 ℃, more preferably 40 to 60 ℃, and the drying time is not particularly limited, preferably 10 seconds to 5 minutes, more preferably 20 to 60 seconds.

The curing temperature in the step (4) is not particularly limited, preferably 60 to 150 ℃, more preferably 80 to 120 ℃, and the curing time is not particularly limited, preferably 1 to 8 hours, more preferably 2 to 6 hours. The organic solvent in the step (4) is dried simultaneously with the curing, if necessary.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following, parts mean parts by weight.

Production example 1 [ production of urethane prepolymer for polyurethane resin (U1-1) used for surface layer ]

The compound (a1) having a polyorganosiloxane group and an active hydrogen, the high-molecular polyol (a2), the aromatic polyisocyanate (b1), the modified organic polyisocyanate (b5) and the organic solvent, the kinds and amounts (parts by weight) of which are shown in table 1, were charged into a vessel equipped with a stirring device and a temperature control device, and reacted at 80 ℃ for 3 hours to obtain a urethane prepolymer for a polyurethane resin (U1-1). The NCO content of the obtained urethane prepolymer was 1.46%.

Production examples 2 to 6 and comparative production examples 1 to 2 [ production of urethane prepolymers for polyurethane resins (U1-2) to U1-5), (U1 '-1) to U1' -2) used for the surface layer ]

Urethane prepolymers for polyurethane resins (U1-2) to (U1-6) used for the skin layer and urethane prepolymers for comparative polyurethane resins (U1 '-1) to (U1' -2) were obtained in the same manner as in production example 1, except that the used raw materials and the used amounts (parts by weight) thereof were changed to those shown in table 1.

[ measurement of elastic recovery of polyurethane resin (U1-1) used for the surface layer ]

The urethane prepolymer (U1-1) obtained in production example 1 and the chain extender (a3) were compounded in a polypropylene beaker according to the formulation shown in table 1. The resulting mixed solution was poured into a polypropylene tray of 11X 17.5cm to a thickness of 200 μm after drying, and was dried at room temperature. After drying, the resulting mixture was cured at 120 ℃ for 2 hours to obtain a sheet of a polyurethane resin (U1-1) for use as a skin layer.

The elastic recovery was measured using the sheet based on the above-described method for measuring the elastic recovery at 100% elongation. The results are shown in table 1.

[ measurement of elastic recovery rates of the polyurethane resins (U1-2) to (U1-6) used for the surface layer and the comparative polyurethane resins (U1 '-1) to (U1' -2) ]

Sheets of the polyurethane resins (U1-2) to (U1-6) used for the surface layer and the comparative polyurethane resins (U1 '-1) to (U1' -2) were obtained in the same manner as in test example 1, except that the urethane prepolymer and the chain extender (a3) used and the amounts (parts by weight) thereof were changed to those shown in Table 1.

The contents of the respective raw materials shown in table 1 are as follows.

< materials of urethane prepolymers for polyurethane resins >

[ Compound (a1) having a polyorganosiloxane group and an active hydrogen group ]

X-22-161A: amino-modified silicone oil [ Mn 1600, R in general formula (1) ]manufactured by shin-Etsu chemical Co., Ltd¹～R⁶Methyl, n-22]

KF-6003: hydroxyl-modified silicone oil [ Mn 5100, R in general formula (1): manufactured by shin-Etsu chemical Co., Ltd¹～R⁶Methyl, n-68]

[ Polymer polyol (a2) ]

KURARAY Polyol C1090: polycarbonate polyol (Mn: 1000) manufactured by KURARAAY K.K

[ aromatic polyisocyanate (b1) ]

4, 4' -MDI: "MilliononteMT" manufactured by Tosoh corporation "

[ modified organic polyisocyanate (b5) ]

Cornate 2793: allophanate group-containing polyisocyanate (average number of functional groups: 5.1) manufactured by Tosoh corporation

[ organic solvent ]

Toluene

< materials for chain extension reaction of urethane prepolymer >

[ chain extender (a3) ]

1, 4-butanediol

Trimethylolpropane

[ organic solvent ]

Methyl Ethyl Ketone

In addition, in the column of "materials for chain extension reaction of urethane prepolymer" in table 1, materials used when each prepolymer used in examples described later was chain extended and the amounts thereof used are described.

[ Table 1]

Production example 7 production of urethane prepolymer for urethane resin (U2-1) used for base layer

The polymer polyol (a2) and the aromatic polyisocyanate (b1) in the types and amounts (parts by weight) shown in table 2 were charged into a vessel equipped with a stirrer and a temperature controller, and reacted at 80 ℃ for 3 hours to obtain a urethane prepolymer for a polyurethane resin (U2-1). The NCO content of the obtained urethane prepolymer was 3.36%.

[ production of urethane prepolymers for polyurethane resins (U2-2) to U2-8), (U2 '-1) to U2' -2) used for the base layer ]

Urethane prepolymers for polyurethane resins (U2-2) to (U2-8) used for the surface 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 amounts (parts by weight) of the urethane prepolymers used were changed to those shown in table 2.

The contents of the various raw materials indicated by symbols or trade names in table 2 are as follows.

< materials of urethane prepolymers for polyurethane resins >

[ Polymer polyol (a2) ]

PTMG-1000: polytetramethylene glycol (Mn 1000) manufactured by Mitsubishi chemical corporation

PTMG-2000: polytetramethylene glycol (Mn 2000) manufactured by Mitsubishi chemical corporation

PTMG-3000: polytetramethylene glycol (Mn 3000) manufactured by Mitsubishi chemical corporation

PRAXCELL 220: polycaprolactone diol (Mn 2000) manufactured by Daicel, Inc

[ polyol having Mn less than 500 ]

SanixPP-400: polypropylene glycol (Mn 400) manufactured by sanyo chemical industries ltd

[ aromatic polyisocyanate (b1) ]

4, 4' -MDI: "Millionate MT" manufactured by Tosoh corporation "

< materials for chain extension reaction of urethane prepolymer >

[ chain extender (a3) ]

1, 4-butanediol

Trimethylolpropane

In table 2, the column entitled "materials for chain extension reaction of urethane prepolymer" describes materials and amounts thereof used when chain extension of the prepolymers used in the test examples and examples described below is performed.

[ measurement of elastic recovery of polyurethane resin (U2-1) used for base layer ]

The polyurethane resin (U2) obtained in production example 7, which had been previously adjusted to 80 ℃, was compounded with the urethane prepolymer and the chain extender (a3) according to the formulation shown in table 2 in a polypropylene beaker, stirred and mixed with a stirrer for 1 minute, and then defoamed under reduced pressure for 2 minutes. The resulting mixture was cast into a SUS-made metal mold having a gap of 2mm, and cured at 120 ℃ for 2 hours to obtain a sheet of a urethane resin (U2-1) for use as a base layer.

The concentration of the crosslinking point and the concentration of the urethane group in the polyurethane resin (U2-1) are shown in Table 2.

The elastic recovery was measured using the sheet based on the above-described method for measuring the elastic recovery at 100% elongation. The results are shown in Table 2.

[ measurement of elastic recovery rates of the urethane resins (U2-2) to (U2-8) used for the base layer and the comparative urethane resins (U2 '-1) to (U2' -2) ]

Sheets of the urethane resins (U2-2) to (U2-8) used for the base layer and the comparative urethane resins (U2 '-1) to (U2' -2) were obtained in the same manner as in test example 7, except that the urethane prepolymer and the chain extender (a3) and the amounts (parts by weight) thereof used were changed to those shown in Table 2.

The concentrations of the crosslinking points and the urethane group concentrations of the polyurethane resins (U2-2) to (U2-8) and the comparative polyurethane resins (U2 '-1) to (U2' -2) are shown in Table 2.

The elastic recovery was measured using these sheets based on the above-described method for measuring the elastic recovery at 100% elongation. The results are shown in Table 2.

[ measurement of elastic recovery of comparative urethane resin (U2' -3) used for base layer ]

150 parts of polyether thermoplastic urethane elastomer "Elastollan 1180A" (manufactured by BASF Japan) was charged into a vessel equipped with a stirrer and a temperature controller, containing 350 parts of toluene, and the vessel was heated to 80 ℃ to dissolve the elastomer. The resulting mixed solution was poured into a polypropylene tray of 11X 17.5cm to a thickness of 400 μm after drying, and was dried at room temperature. Further, the resulting mixture was dried for 2 hours in a vacuum drier at 100 ℃ to obtain a comparative urethane resin (U2' -3) sheet used as a base layer.

< example 1> [ production of multilayer film ]

496.1 parts (total amount of urethane prepolymer material shown in table 1) of urethane prepolymer for the polyurethane resin for a surface layer (U1-1) obtained in production example 1, 7.6 parts of 1, 4-butanediol as a material for chain extension reaction of urethane prepolymer shown in table 1 and 496.3 parts of methyl ethyl ketone were mixed, and the mixture was applied to a release film so that the film thickness after drying was 10 μm, and dried with a circulating air dryer at 50 ℃ for 30 seconds to volatilize the solvent, thereby producing a polyurethane resin for a surface layer.

The urethane resin (U2-1) for polyurethane resin obtained in production example 7 was compounded with a chain extender (a3) according to the formulation shown in Table 2, applied to a urethane resin for surface layer to a film thickness of 400 μm, cured at 120 ℃ for 2 hours, and then the release film was peeled off to obtain a multilayer film having a urethane resin (U1-1) for surface layer and a urethane resin (U2-1) for base layer.

< examples 2 to 19 and comparative examples 1 to 4>

Multilayer films of examples 2 to 19 and comparative examples 1 to 4 were obtained in the same manner as in example 1, except that the combination of the urethane resin for the surface layer and the urethane resin for the base layer was changed to the combination shown in table 3.

< comparative example 5>

The polyurethane resin for a surface layer (U1-1) obtained in the same manner as in example 1 was coated with a urethane prepolymer onto a 400 μm thick polyurethane resin (U2' -3) sheet obtained in the same manner as in comparative test example 5, and the film thickness after drying was set to 10 μm, dried for 30 seconds by a circulating air dryer at 50 ℃ and further cured for 2 hours at 120 ℃ to obtain a multilayer film of comparative example 5.

The multilayer film obtained was evaluated for scratch resistance by the following evaluation method, and the results are shown in table 3.

[ method for evaluating scratch resistance ]

Steel wool (No.0000) manufactured by japan steel wool company was attached to a "TriboGear model manufactured by new eastern science corporation: 40' steel wool is fixed on a fixture, and each 1cm²The multilayer films obtained in examples and comparative examples were subjected to a load of 100g, and the occurrence of damage after repeated rubbing of the surface layer side was observed for a length of 5cm, and evaluated based on the following criteria. The results are shown in Table 3.

< evaluation criteria >

Very good: no damage is generated after more than 500 times of reciprocating.

O: damage is generated when the reciprocating motion is more than 300 times and less than 500 times.

X: damage occurs with less than 300 reciprocations.

[ method for evaluating Flex resistance ]

For the multilayer films obtained in examples and comparative examples, samples having dimensions of 50mm in the width direction (direction of the folded portion) × 100mm in the flow direction (bending direction) were prepared. A bending radius was set to 3mm using a no-load U-shaped stretching machine (DLDMLH-FS) and the tube was bent 5 ten thousand times at a speed of 1 time/second. At this time, the positions of both ends on the long side of the sample were fixed at 10mm, and the bent portions were set to 50mm × 80 mm. After the bending treatment was completed, the sample was placed on a flat surface with the bent inner side facing downward, and visual inspection was performed.

< evaluation criteria >

Very good: the sample was not deformed; alternatively, even with deformation, the maximum height of the bulge is less than 3mm when placed horizontally.

O: the sample was deformed and when placed horizontally, the maximum height of the bulge was 3mm or more and less than 5 mm.

X: the sample had creases; alternatively, the maximum height of the bulge is 5mm or more when the container is placed horizontally.

[ Table 3]

Industrial applicability

The polyurethane resin of the present invention is excellent in scratch resistance and also excellent in flexing resistance, and therefore is suitably used as a surface protective film for optical members, particularly for touch devices.

Claims

1. A multilayer film which is a multilayer film having a base layer and a skin layer formed on the base layer, wherein,

the surface layer contains a polyurethane resin (U1) comprising an active hydrogen component (A1) and an isocyanate component (B1), the active hydrogen component (A1) contains a compound (a1) having a polyorganosiloxane group and an active hydrogen group as essential components, the polyurethane resin (U1) has an elastic recovery rate of 50 to 100% at 100% elongation,

the base layer contains a urethane resin (U2) comprising an active hydrogen component (A2) and an isocyanate component (B2), the active hydrogen component (A2) is an active hydrogen component containing not the compound (a1) having the polyorganosiloxane group and the active hydrogen group but containing a polymer polyol (a2) as an essential component, and the urethane resin (U2) has an elastic recovery rate of 80% to 100% at 100% elongation.

2. The multilayer film according to claim 1, wherein the polyorganosiloxane group is a polyorganosiloxane group represented by the general formula (1),

[ solution 1]

In the formula, R¹～R⁶Each independently represents a hydrocarbon group having 1 to 6 carbon atoms, and n is an integer of 1 to 100.

3. The multilayer film according to claim 1 or 2, wherein the weight of the compound (a1) having a polyorganosiloxane group and an active hydrogen group as a constituent component is 0.5 to 5% by weight based on the weight of the urethane resin (U1).

4. The multilayer film according to any one of claims 1 to 3, wherein the polymer polyol (a2) is a polymer polyol containing polytetramethylene glycol.

5. The multilayer film according to any one of claims 1 to 4, wherein the concentration of the crosslinking points of the polyurethane resin (U2) is from 0.05 to 0.25mmol/g, the concentration of the urethane groups of the polyurethane resin (U2) is from 1.0 to 2.0mmol/g, and the concentration of the urethane groups is the total concentration of urethane groups and urea groups in the presence of urea groups.

6. The multilayer film according to any one of claims 1 to 5, wherein the surface layer has a film thickness of 1 to 50 μm, and the base layer has a film thickness of 100 to 1000 μm.

7. The multilayer film according to any one of claims 1 to 6, which is used as a surface protective film for optical parts.