JP2010095560A - Protective adhesive sheet - Google Patents

Abstract

The present invention provides a protective pressure-sensitive adhesive sheet having chipping resistance and weather resistance.
A protective pressure-sensitive adhesive sheet has a base material and a pressure-sensitive adhesive layer, and the base material is a composite film made of a mixture containing an acrylic polymer and a urethane polymer. The acrylic polymer is an acrylic acid-based film. Using an acrylic component comprising a monomer, a monofunctional acrylic monomer having a glass transition temperature (Tg) of a homopolymer of 273 K or more, and a monofunctional acrylic monomer having a glass transition temperature (Tg) of a homopolymer of less than 273 K Become. The acrylic monomer content is 1% by weight or more and 30% by weight or less in the acrylic component, the urethane polymer is composed of diol and diisocyanate, and the urethane polymer is NCO / OH (equivalent ratio) = 1. .1 to 2.0. The composite film contains DMF solubles.
[Selection figure] None

Description

  The present invention relates to a protective pressure-sensitive adhesive sheet, and particularly relates to a protective pressure-sensitive adhesive sheet used for protecting a coating film and the like.

  When an automobile or the like travels, dust, pebbles, etc. may be splashed up by wheels or the like and collide with the body painted surface, and this collision is likely to occur frequently particularly on a road surface with bad road conditions. Also, when driving on roads, etc. where rock salt, sand, gravel, etc. are sprayed to remove snow in cold regions, the painted surface is easily damaged by the impact of rock salt, sand, etc., and rust is generated from the damaged portion of the painted surface. There is a problem that occurs. In the automobile industry, colorless and transparent adhesive tapes (chipping tapes) are sometimes affixed to prevent damage to the painted surface of an automobile body, and a polyurethane substrate is used as the substrate of the transparent adhesive tape ( For example, refer to JP 59-41376 A and JP 2005-272558 A).

  However, polyurethane is known to generate a colored substance having a conjugated structure or a nitrogen-containing colored substance by a photoreaction. Accordingly, a film containing polyurethane is initially colorless and transparent. However, when the film is left outdoors, it may be yellowed by exposure to ultraviolet rays, and the gloss may be lost and the aesthetic appearance may be lowered.

JP 59-41376 JP 2005-272558 A

  The present invention has been made to solve the above problems, and the present invention is excellent in strength and chipping resistance, and does not turn yellow even when used outdoors for a long period of time. An object of the present invention is to provide a protective pressure-sensitive adhesive sheet having weather resistance that can be maintained.

  The protective pressure-sensitive adhesive sheet of the present invention is a composite film comprising a base material and a protective pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one side of the base material, the base material comprising a mixture containing an acrylic polymer and a urethane polymer. The acrylic polymer is an acrylic acid monomer, a monofunctional acrylic monomer having a glass transition temperature (Tg) of the homopolymer of 273 K or more, and a single polymer having a glass transition temperature (Tg) of the homopolymer of less than 273 K. It comprises an acrylic component containing a functional acrylic monomer, and the content of the acrylic acid monomer is 1% by weight or more and 30% by weight or less in the acrylic component, and the urethane polymer uses diol and diisocyanate. The urethane polymer is NCO / OH (equivalent ratio) = 1.1 to 2.0, and Film N, and having a N- dimethylformamide (DMF) soluble matter.

  Here, the composite film preferably has a gel fraction of 50% or more and 99.5% or less.

  In the present invention, the composite film uses the acrylic component as a solvent, forms a urethane polymer by thermally polymerizing the diol and the diisocyanate in the solvent, and forms a sheet by adding a photopolymerization initiator. Thereafter, it can be obtained by ultraviolet irradiation.

  In the present invention, the composite film preferably has a water absorption of 4% or less.

  In the present invention, the pressure-sensitive adhesive layer contains as a main component at least one selected from the group consisting of 2-ethylhexyl acrylate and isononyl acrylate and at least one selected from the group consisting of acrylic acid and methacrylic acid. It preferably consists of an adhesive.

  In the present invention, the substrate has a fluorine-containing polymer layer on one surface of the composite film, and the fluorine-containing polymer layer is on the surface opposite to the surface on which the pressure-sensitive adhesive layer is provided. Can be arranged.

  In the present invention, the protective pressure-sensitive adhesive sheet is preferably used by being adhered to at least one exterior coating film surface selected from the group consisting of automobiles and aircraft.

According to the present invention, it is possible to provide a protective pressure-sensitive adhesive sheet having high strength and weather resistance. For example, it can maintain glossiness without being yellowed even when used outdoors for a long period of time. The protective adhesive sheet which can be provided can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.
The protective pressure-sensitive adhesive sheet of the present invention has a base material and a pressure-sensitive adhesive layer, and the base material has a composite film. That is, the base material may be composed only of the composite film, or may have other layers in addition to the composite film.

The composite film according to the present invention comprises a mixture containing an acrylic polymer and a urethane polymer.
The acrylic polymer includes an acrylic acid monomer, a monofunctional acrylic monomer having a glass transition temperature (Tg) of a homopolymer of 273K or higher, and a monofunctional acrylic having a glass transition temperature (Tg) of the homopolymer of less than 273K. An acrylic component containing a monomer is used.

  In the present invention, the acrylic acid monomer is preferably, for example, acrylic acid, but may be methacrylic acid or a mixture of acrylic acid and methacrylic acid. In the present invention, a monomer having an acidic group may be mixed. Examples of monomers having an acidic group that can be mixed include carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, acrylic acid, methacrylic acid and the like. Group-containing monomers, sulfonic acid group-containing monomers such as 2-acrylamido-2-methylpropanesulfonic acid, phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate, 2-hydroxypropyl acryloyl phosphate, etc. Can be mentioned.

  In the present invention, monofunctional acrylic monomers having a homopolymer glass transition temperature of 0 ° C. or higher, or monofunctional acrylic monomers having a homopolymer glass transition temperature of less than 0 ° C. include, for example, methyl (meth) acrylate, Ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, Pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethyl Xyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl ( (Meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl ( And (meth) acrylate. One or more types of these monofunctional acrylic monomers having a Tg of 0 ° C. or more and monofunctional acrylic monomers having a Tg of less than 0 ° C. are used.

  In the present invention, as monofunctional acrylic monomers having a Tg of 0 ° C. or higher, isobornyl (meth) acrylate, methyl (meth) acrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate It is preferable to use n-butyl acrylate, propyl acrylate, 2-ethylhexyl (meth) acrylate, or the like as the monofunctional acrylic monomer having a Tg of less than 0 ° C.

  The content of the acrylic acid monomer in the acrylic component is 1% by weight or more and 30% by weight or less, and preferably 5% by weight or more and 20% by weight or less. When the content of the acrylic acid monomer is less than 1% by weight, it takes a long time for the reaction, making it very difficult to form a film, and the strength of the film is not sufficient. When the content of the acrylic acid monomer exceeds 30% by weight, the water absorption of the film increases and the water resistance decreases. In the present invention, the acrylic acid-based monomer greatly affects the compatibility with the urethane component and the acrylic component, and is an essential component having a very important function.

In the present invention, the term “film” includes a sheet, and the term “sheet” includes a film.
In the present invention, when “(meth) acryl” is displayed, such as (meth) acrylate and (meth) acrylic acid, it means acrylic and / or methacrylic. In addition, when the same expression is used in the present invention, it has the same meaning as described above unless otherwise specified. Furthermore, even when “acrylic” is simply displayed, there is no particular notice, and if there is no problem in general common sense, it will be understood to include methacryl.

  The content of the monofunctional acrylic monomer having a Tg of 0 ° C. or more in the homopolymer is preferably 20% by weight or more and 99% by weight or less in the acrylic component, and is 30% by weight or more and 98% by weight or less. Is more preferable. If the content of the monofunctional acrylic monomer is less than 20% by weight, there may be a problem that the strength of the film is not sufficient. If it exceeds 99% by weight, the rigidity of the film may be excessively increased and become brittle.

  The content of the monofunctional acrylic monomer having a Tg of less than 0 ° C. in the homopolymer is preferably 5% by weight or more and 50% by weight or less in the acrylic component, and is 10% by weight or more and 45% by weight or less. Is more preferable. When the content of the monofunctional acrylic monomer is 5% by weight or more and 50% by weight or less, sufficient chipping resistance can be obtained.

  The monofunctional acrylic monomer having a Tg of 0 ° C. or more and the monofunctional acrylic monomer having a Tg of less than 0 ° C. are compatible with urethane, polymerizable at the time of photocuring such as radiation, and a high molecular weight product to be obtained. The type, combination, amount used, etc. are appropriately determined in consideration of the above characteristics and the like.

In the present invention, the following monomers can be copolymerized together with a monofunctional acrylic monomer having a Tg of 0 ° C. or higher and a monofunctional acrylic monomer having a Tg of less than 0 ° C. of the homopolymer. Examples of such a monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, ( Hydroxyl group-containing monomers such as 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) -methyl acrylate; glycidyl (meth) Glycidyl group-containing monomers such as acrylate and methylglycidyl (meth) acrylate, cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, N-vinyl 2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-2-pyrrolidone, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5 -Nitrogen-containing monomers such as morpholinedione, N-cyclohexylmaleimide, N-phenylmaleimide, N-acryloylpyrrolidine, t-butylaminoethyl (meth) acrylate, vinyl acetate, styrene and the like.
In addition, the kind and usage-amount of these monomers are suitably determined in consideration of the characteristic etc. of a composite film.

  In addition, other polyfunctional monomers can be added within a range that does not impair the characteristics. Examples of the polyfunctional monomer include 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 2-n-butyl- 2-ethyl-1,3-propanediol diacrylate, tripropylenediol diacrylate, tetraethylenediol diacrylate, neopentyldiol diacrylate, neopentyldiol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, tris ( 2-acryloyloxyethyl) isocyanurate, pentaerythritol tetraacrylate and the like. Among these, trimethylolpropane tri (meth) acrylate is preferable.

  The polyfunctional monomer is added in an amount of 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the total amount of the monofunctional acrylic monomer having a Tg of 0 ° C. or more and the monofunctional acrylic monomer having a Tg of less than 0 ° C. be able to. If the content of the polyfunctional monomer is 1 part by weight or more, the strength of the composite film is sufficient, and if it is 20 parts by weight or less, the elastic modulus does not become too high and follows the unevenness of the adherend surface. can do.

The urethane polymer is obtained by reacting a diol with a diisocyanate.
Examples of the diol used in the present invention include ethylene diol, 1,4-butylene diol, 1,6-hexane diol, 1,12-dodecane diol, neopentyl diol, 3-methyl-1,5-pentane diol, Diethylene diol, poly (oxypropylene) diol, poly (oxytetramethylene) diol, aliphatic polyester polyol (condensate of aliphatic diol and aliphatic dibasic acid; for example, aliphatic diol includes ethylene diol, 1 , 4-Butylenediol, 1,6-hexanediol, neopentyldiol, 3-methyl-1,5-pentanediol, diethylenediol, and aliphatic dibasic acids include succinic acid, adipic acid, sebacic acid, Decamethylene dicarboxylic acid), polycaprolactone polio And polycarbonate polyols (adducts of aliphatic diol and ethylene carbonate, condensates of aliphatic diol and dimethyl carbonate, condensates of aliphatic diol and diethyl carbonate; for example, aliphatic diols include ethylene diol, 1,4- Butylene diol, 1,6-hexanediol, neopentyldiol, 3-methyl-1,5-pentanediol, diethylenediol) and the like. These diols can be used alone or in combination of two or more. Among these, for example, poly (oxytetramethylene) diol (hereinafter sometimes abbreviated as “PTMG”) and the like are preferably used. The type and amount of diol can be freely selected according to the use and purpose, and from the viewpoint of reactivity with isocyanate, compatibility with acrylic, and the like.

  In the present invention, the urethane polymer does not contain a crosslinked structure. The diol used for forming the urethane polymer is preferably a linear (linear) diol. However, the diol may be a side chain diol or a diol containing a branched structure as long as the condition that the urethane polymer does not form a crosslinked structure is satisfied.

Examples of the diisocyanate used in the present invention include hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and norbornene diisocyanate. It is done. These diisocyanates can be used alone or in combination of two or more. Use of an aromatic diisocyanate containing a benzene ring is not preferable because a colored substance having a conjugated structure is easily generated by a photoreaction. In the present invention, non-yellowing and non-yellowing aliphatic and alicyclic diisocyanates that do not contain a benzene ring are preferably used. In the present invention, it is preferable to use hydrogenated xylylene diisocyanate.
In addition, from the viewpoint of solubility in a monofunctional acrylic monomer, reactivity with a hydroxyl group, and the like, the type and combination of diisocyanates can be appropriately selected.

  In the present invention, the amount of the diol component and diisocyanate component used to form the urethane polymer is preferably NCO / OH (equivalent ratio) of 1.1 or more and 2.0 or less, preferably 1.12 or more, 1 Is more preferably 1.60 or less, and particularly preferably 1.15 or more and 1.35 or less. When the NCO / OH (equivalent ratio) is less than 1.1, the molecular weight of the urethane polymer becomes too large, the viscosity of the composite film precursor (syrup solution) becomes large, and the work becomes difficult in the subsequent sheeting process. In addition, the strength of the obtained base material tends to decrease. Moreover, if NCO / OH (equivalent ratio) is 2.0 or less, the elongation and flexibility of the obtained base material can be sufficiently ensured.

  In general, a catalyst is used for the reaction between the hydroxyl group of the diol and the isocyanate. However, according to the present invention, the reaction is promoted without using an environmental load catalyst such as dibutyltin dilaurate or tin octoate. Can be made.

  In the composite film constituting the substrate in the present invention, first, the glass transition temperature (Tg) of the acrylic monomer, the monofunctional acrylic monomer having a glass transition temperature (Tg) of the homopolymer of 0 ° C. or higher, and the homopolymer is 0. Using a monofunctional acrylic monomer at a temperature of less than 0 ° C., a diol and a diisocyanate are reacted and a urethane polymer is formed by thermal polymerization to produce a urethane polymer-acrylic monomer mixture (syrup). Thereafter, a photopolymerization initiator, an ultraviolet absorber and a light stabilizer are added, and ultraviolet rays and the like are irradiated to produce a composite film.

  In the reaction between the diol and the diisocyanate, the reaction temperature and reaction time can be appropriately set. For example, the inner bath temperature is preferably 20 ° C. or higher and 90 ° C. or lower, more preferably 40 ° C. Above, it is 80 degrees C or less, Especially preferably, it is 50 degrees C or more and 75 degrees C or less. The reaction time is preferably 1 hour or more and 48 hours or less, more preferably 3 hours or more and 24 hours or less, and particularly preferably 5 hours or more and 15 hours or less.

  Various photopolymerization initiators can be used as the photopolymerization initiator used here. For example, ketal photopolymerization initiators, α-hydroxyketone photopolymerization initiators, α-aminoketone photopolymerization initiators can be used. Polymerization initiator, acylphosphine oxide photopolymerization initiator, bezophenone photopolymerization initiator, thioxanthone photopolymerization initiator, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator Agents, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, and the like can be used.

  Examples of the ketal photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one (for example, “Irgacure 651” manufactured by Ciba Specialty Chemicals Co., Ltd.). Etc.).

  Examples of the α-hydroxyketone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (commercially available products such as “Irgacure 184” manufactured by Ciba Specialty Chemicals), 2-hydroxy- 2-methyl-1-phenylpropan-1-one (commercially available products such as “Darocur 1173” manufactured by Ciba Specialty Chemicals), 1- [4- (2-hydroxyethoxy)- Phenyl] -2-hydroxy-2-methyl-1-propan-1-one (commercially available products such as “Irgacure 2959” manufactured by Ciba Specialty Chemicals) and the like.

  As the α-aminoketone photopolymerization initiator, for example, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (commercially available is Ciba “Irgacure 907” manufactured by Specialty Chemicals Co., Ltd.), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (commercially available products include Ciba Specialty Chemicals "Irgacure 369" etc.).

  Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (commercially available products such as “Lucirin TPO” manufactured by BASF).

  Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole. And methyl ether.

  Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl). Examples include dichloroacetophenone.

  Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride, and examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (O-ethoxycarbonyl) -oxime and the like.

  Examples of the benzoin photopolymerization initiator include benzoin, and examples of the benzyl photopolymerization initiator include benzyl.

  Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like.

  Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

Examples of the ultraviolet absorber (UVA) used in the present invention include 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (commercially available) as a benzotriazole ultraviolet absorber. Examples include “TINUVIN PS” manufactured by Ciba Japan Ltd.), benzenepropanoic acid and 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C ester compounds with a side chain and straight chain alkyl) of ₇ -C ₉ (as the ones commercially available, manufactured by Ciba Japan K.K. "TINUVIN 384-2", etc.), octyl -3- [3-tert -Butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl A mixture with -3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (commercially available, Ciba Japan “TINUVIN 109”, etc.), 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (commercially available, “TINUVIN 900” manufactured by Japan Ltd.), 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethyl) Butyl) phenol (as commercially available products such as “TINUVIN 928” manufactured by Ciba Japan), methyl-3- (3- (2H-benzotriazole-2) -Yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product (as commercially available, “TINUVIN 1130” manufactured by Ciba Japan Co., Ltd.), 2- ( 2H-benzotriazol-2-yl) -p-cresol (as commercially available “TINUVIN P” manufactured by Ciba Japan), 2- [5-chloro (2H) -benzotriazole-2 -Yl] -4-methyl-6- (tert-butyl) phenol (commercially available, "TINUVIN 326" manufactured by Ciba Japan), 2- (2H-benzotriazol-2-yl ) -4,6-di-tert-pentylphenol (as a commercially available product, “TINU manufactured by Ciba Japan Ltd.) IN 328 "), 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (commercially available, manufactured by Ciba Japan Co., Ltd.) “TINUVIN 329”, etc.) of 2-2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (commercially available) As possible, “TINUVIN 360” manufactured by Ciba Japan Ltd.), methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene Reaction product with glycol 300 (such as “TINUVIN 213” manufactured by Ciba Japan as commercially available product), 2- (2H-benzoto Riazol-2-yl) -6-dodecyl-4-methylphenol (such as “TINUVIN 571” manufactured by Ciba Japan as commercially available), 2- [2-hydroxy-3- (3, 4,5,6-tetrahydrophthalimido-methyl) -5-methylphenyl] benzotriazole (as commercially available, “Sumisorb 250” manufactured by Sumitomo Chemical Co., Ltd.), 2,2′-methylenebis [6- (Benzotriazol-2-yl) -4-tert-octylphenol] (as commercially available products such as “ADKSTAB LA31” manufactured by ADEKA, etc.), hydroxyphenyltriazine (HPT) type benzotriazole (BTZ) type ultraviolet ray Absorbent (as commercially available, “TINUVIN 5236” manufactured by Ciba Japan Etc.), “TINUVIN 234 etc.” manufactured by Ciba Japan.

  Examples of commercially available hydroxyphenyl triazine-based ultraviolet absorbers include 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5- Reaction product of hydroxyphenyl and [(C10-C16, mainly C12-C13 alkyloxy) methyl] oxirane (as commercially available, “TINUVIN 400” manufactured by Ciba Japan), 2- Reactive organisms of (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester (commercially As available, “TINUVIN 405” manufactured by Ciba Japan Ltd.), 2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3,5-triazine (as commercially available, “TINUVIN 460” manufactured by Ciba Japan Co., Ltd.), 2- (4,6-diphenyl-1 , 3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol (such as commercially available “TINUVIN 1577” manufactured by Ciba Japan), 2- (2- Hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine (commercially available, manufactured by Ciba Japan “TINUVIN 479”) and the like.

Examples of commercially available benzophenone ultraviolet absorbers include “CHIMASSORB 81” manufactured by Ciba Japan. Examples of the benzoate UV absorber include “TINIVIN 120” manufactured by Ciba Japan as 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate. Can be mentioned.
In this invention, the said ultraviolet absorber can be used individually or in combination of 2 or more types.

  The light stabilizer used in the present invention is preferably a hindered amine light stabilizer (HALS).

As a commercially available hindered amine light stabilizer, for example, as a light stabilizer which is a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, TINUVIN 622 "(manufactured by Ciba Japan), a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and N, N ', N", N''' -Tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7- As a light stabilizer which is a one-to-one reaction product with diazadecane-1,10-diamine, “TINUVIN 119” (manufactured by Ciba Japan), dibutylamine, 1,3-triazine, N, N′-bis ( , 2,6,6-Tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine As the agent, “TINUVIN 2020” (manufactured by Ciba Japan), poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {2 , 2,6,6-Tetramethyl-4-piperidyl} imino] hexamethylene {(2,6,6-tetramethyl-4-piperidyl) imino}) as a light stabilizer, “TINUVIN 944” (Ciba Japan)), photostability that is a mixture of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate Agent and “TINUVIN 765” (manufactured by Ciba Japan), “TINUVIN 770” (manufactured by Ciba Japan), decane as a light stabilizer that is bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate As a light stabilizer which is a reaction product of diacid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester (1,1-dimethylethyl hydroperoxide) and octane “TINUVIN 123” (manufactured by Ciba Japan), bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl ] [TINUVIN 144] (manufactured by Ciba Japan) as light stabilizer which is methyl] butyl malonate, cyclohexane and N-butyl peroxide 2,2,6 “TINUVIN 152” is a light stabilizer that is a reaction product of 6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1,3,5-triazine and 2-aminoethanol. (Ciba Japan), mixture of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate As a light stabilizer, “TINUVIN 292” (manufactured by Ciba Japan), “TINUVIN 5100” (manufactured by Ciba Japan), and as a high molecular weight type hindered amine light stabilizer, “CHIMASSORB 119FL” (Ciba Japan) ), “CHIMASSORB 2020FDL” (manufactured by Ciba Japan), “CHIMASSORB 944 “DL” (manufactured by Ciba Japan), “TINUVIN 622LD” (manufactured by Ciba Japan), “TINUVIN 111FDL” (manufactured by Ciba Japan), “TINUVIN 783FDL” (Ciba) as blend type hindered amine light stabilizers・ Japan), “TINUVIN 791FB” (Ciba Japan), blend type of UV absorber and light stabilizer, “TINUVIN 5050” (Ciba Japan), “TINUVIN 5060” (Ciba Japan), “TINUVIN 5151” (manufactured by Ciba Japan), and the like.
In the present invention, the above hindered amine light stabilizers can be used alone or in combination of two or more.

  If necessary, the composite film is added with commonly used additives such as anti-aging agents, fillers, pigments, colorants, flame retardants, antistatic agents and the like within a range that does not impair the effects of the present invention. be able to. These additives are used in normal amounts depending on the type. These additives may be added in advance before the polymerization reaction between the diisocyanate and the diol, or may be added before the urethane polymer and the acrylic monomer are polymerized.

  In the present invention, a small amount of solvent may be added to adjust the viscosity of the coating. The solvent can be appropriately selected from commonly used solvents, and examples thereof include ethyl acetate, toluene, chloroform, dimethylformamide and the like.

  In the present invention, the composite film includes, for example, an acrylic monomer as a diluent, a reaction between diol and diisocyanate in the acrylic monomer to form a urethane polymer, and the acrylic monomer and the urethane polymer as main components. Apply the mixture onto a support (exfoliated if necessary), etc., and ionize α rays, β rays, γ rays, neutron rays, electron rays, etc., depending on the type of photopolymerization initiator A composite film can be formed by irradiating and curing radiation such as actinic radiation and ultraviolet rays, visible light, and the like, and then peeling and removing the support and the like. Or it can also obtain in the form by which the composite film was laminated | stacked on the support body etc., without peeling and removing a support body etc.

  Specifically, after dissolving the diol in the acrylic monomer, diisocyanate or the like is added and reacted with the diol to adjust the viscosity, and this is peeled off to the support or the like, or if necessary, the support or the like is peeled off After coating on the treated surface, the composite film can be obtained by curing using a low-pressure mercury lamp or the like. In this method, the acrylic monomer may be added all at once during the urethane synthesis, or may be added in several divided portions. Further, after the diisocyanate is dissolved in the acrylic monomer, the diol may be reacted. According to this method, the molecular weight is not limited and a high molecular weight polyurethane can be produced, so that the molecular weight of the finally obtained urethane can be designed to an arbitrary size.

  At this time, in order to avoid polymerization inhibition due to oxygen, a release sheet (separator, etc.) may be placed on the mixture coated on the substrate sheet, etc. to block oxygen, or filled with an inert gas. The oxygen concentration may be lowered by placing a substrate in the container.

  In the present invention, the type of radiation and the type of lamp used for irradiation can be selected as appropriate, such as a low-pressure lamp such as a fluorescent chemical lamp, a black light and a sterilization lamp, a high-pressure such as a metal halide lamp and a high-pressure mercury lamp. A lamp or the like can be used.

Irradiation amounts such as ultraviolet rays can be arbitrarily set according to required film characteristics. Generally, the dose of ultraviolet rays, 100~5,000mJ / cm ^2, preferably not 1,000~4,000mJ / cm ^2, more preferably a 2,000~3,000mJ / cm ^2. When the irradiation amount of ultraviolet rays is less than 100 mJ / cm ² , a sufficient polymerization rate may not be obtained, and when it is more than 5,000 mJ / cm ² , deterioration may be caused.

  In addition, the temperature at the time of irradiation with ultraviolet rays or the like is not particularly limited and can be arbitrarily set. However, if the temperature is too high, a termination reaction due to polymerization heat is likely to occur, which may cause deterioration of characteristics. The temperature is usually 70 ° C. or lower, preferably 50 ° C. or lower, more preferably 30 ° C. or lower.

  The thickness of the composite film according to the present invention can be appropriately selected according to the purpose and the like, for example, according to the type and location of the object to be covered and protected, and is not particularly limited, but is 50 μm or more and 1 mm or less. Is preferably 100 μm or more and 500 μm or more, and particularly preferably 150 μm or more and 400 μm or less.

  In the present invention, the weight ratio of the acrylic polymer to the urethane polymer in the composite film is preferably in the range of acrylic polymer / urethane polymer = 1/99 to 80/20. If the acrylic polymer content ratio is less than 1/99, the viscosity of the mixed solution for forming a composite film (urethane polymer-acrylic monomer syrup) may increase, and workability may deteriorate. In some cases, flexibility and strength as a film cannot be obtained.

The composite film according to the present invention has an N, N-dimethylformamide (DMF) soluble content. Here, having N, N-dimethylformamide (DMF) soluble content means having a component that dissolves by being immersed in N, N-dimethylformamide (DMF) at 40 ° C. for 7 days. The degree of this DMF soluble part can be shown by a gel fraction. The gel fraction can be determined as follows, for example. That is, about 0.1 g is weighed from the composite film to prepare a sample, and the sample is wrapped in a stainless steel 200 mesh wire net, immersed in N, N-dimethylformamide (DMF) and stored at 40 ° C. for 7 days. Thereafter, the wire mesh is taken out from the DMF and the sample is taken out from the wire mesh, and then the sample is dried at 130 ° C. for 2 hours and cooled. The weight of the dried sample is measured, and the gel fraction is determined by substituting it into the following formula. However, the weight of the sample before dipping in DMF is the weight of the sample after being dried at 130 ° C. for 1 hour.

Gel fraction (%) = (weight of sample after DMF immersion / weight of sample before DMF immersion) × 100

  In the present invention, the gel fraction of the composite film is preferably 50% or more and 99.5% or less, more preferably 60% or more and 99.5% or less, particularly preferably 75% or more and 99.5% or less. When the gel fraction is 50% or more and 99.5% or less, it is excellent in transparency and solvent resistance and can have high strength.

  In the present invention, the water absorption rate of the substrate is preferably 4% or less, more preferably 3.5% or less, and particularly preferably 3% or less. If the water absorption rate of the substrate exceeds 4%, the water resistance tends to decrease. Therefore, when water is contained in the substrate, the mechanical properties are likely to be lowered, the substrate is plasticized with water and becomes flexible, and the chipping resistance is likely to be lowered.

  The base material constituting the protective pressure-sensitive adhesive tape of the present invention preferably has an upper yield point stress in a tensile test of 1.0 MPa or more and 5.0 MPa or less. When the upper yield point stress is less than 1.0 MPa, the mechanical properties of the base material are likely to deteriorate, and the base material may become flexible and chipping resistance may decrease. On the other hand, if the upper yield point stress exceeds 5.0 MPa, the base material tends to become rigid at low temperatures, so that when pebbles or the like collide with the protective adhesive sheet, the surface is likely to be scratched and chipping resistance is reduced. There are things to do.

  The tensile test of the substrate was performed as follows. That is, after immersing the base material in warm water of 40 ° C. for 24 hours, the base material is taken out and lightly pressed with a paper waste on the surface to remove water droplets adhering to the base material surface. A test was conducted. Moreover, the conditions of the tensile test are that the width of the test piece is 10 mm, the distance between the grips is 50 mm, and the tensile speed is 200 mm / min.

  The base material constituting the protective pressure-sensitive adhesive sheet of the present invention preferably has a breaking strength in a tensile test of 10 MPa or more and 100 MPa or less, more preferably 15 MPa or more and 80 MPa or less, particularly 20 MPa or more and 60 MPa or less. It is preferable that However, the conditions of the tensile test are that the width of the test piece is 10 mm, the distance between the grips is 50 mm, and the tensile speed is 200 mm / min. When the breaking strength of the substrate is less than 10 MPa, the substrate is likely to be flexible, and chipping resistance may be reduced. Therefore, when pebbles or the like collide with the protective pressure-sensitive adhesive sheet, the surface of the sheet is damaged, and the aesthetic appearance of the coating film of an automobile or the like is easily impaired. On the other hand, when the breaking strength of the substrate exceeds 100 MPa, the substrate may become too rigid, and the curved surface followability of a coating film of an automobile or the like is lowered at the time of pasting, and floating tends to occur.

  The protective pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer on one surface of the substrate. The pressure-sensitive adhesive that forms this pressure-sensitive adhesive layer is not particularly limited, and general materials such as acrylic, rubber-based, silicon-based, etc. can be used, but adhesion at low temperatures and retention at high temperatures, In view of cost and the like, an acrylic adhesive is preferable.

  As an acrylic adhesive, an acrylic copolymer obtained by copolymerizing a monomer component mainly composed of an acrylate ester and a monomer component having a functional group such as a carboxyl group or a hydroxyl group (may be two or more types) An acrylic pressure-sensitive adhesive containing can be used.

  Examples of acrylic esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec- Butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) Acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, Sil (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl ( And (meth) acrylate, eicosyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, and the like. These alkyl (meth) acrylates can be used alone or in combination of two or more.

  The following monomer components can be copolymerized with the alkyl (meth) acrylate. Examples of copolymerizable monomer components include (meth) acrylic acid, itaconic acid, maleic acid, crotonic acid, isocrotonic acid, fumaric acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, and other carboxyl groups. Containing monomer: 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, (meth) acrylic acid Hydroxyl group-containing monomers such as 8-hydroxyoctyl, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) -methyl acrylate; glycidyl (meth) acrylate, methyl glycidyl Glycidyl group-containing monomers such as (meth) acrylate; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N- Dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, N-vinyl-2-piperidone, N-vinyl -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-2-pyrrolidone, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-cyclohexylmaleimide N-Phenylmer Imide, N- acryloyl pyrrolidine, nitrogen-containing monomers such as t- butyl aminoethyl (meth) acrylate, derivatives of styrene and styrene monomers such as vinyl acetate and the like. One or more of these monomers can be used by copolymerizing with (meth) acrylic acid ester as required.

  The pressure-sensitive adhesive used in the present invention comprises at least one selected from the group consisting of 2-ethylhexyl acrylate and isononyl acrylate, and at least one carboxyl group-containing monomer selected from the group consisting of acrylic acid and methacrylic acid. It is preferable to include. That is, the pressure-sensitive adhesive used in the present invention can use a copolymer obtained by copolymerizing 2-ethylhexyl acrylate, isononyl acrylate, or the like as a main monomer and a carboxyl group-containing monomer such as acrylic acid or methacrylic acid. .

  In the pressure-sensitive adhesive used in the present invention, a polyfunctional (meth) acrylic monomer can be used as a crosslinking agent. Examples of the polyfunctional (meth) acrylic monomer used here include 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, and the like. Is mentioned.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited and can be arbitrarily set. Usually, it is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 30 μm or more. Moreover, it is preferable that the thickness of an adhesive layer is 300 micrometers or less, More preferably, it is 200 micrometers or less, Especially preferably, it is 100 micrometers or less.

  In the present invention, the pressure-sensitive adhesive layer is formed by, for example, applying a solvent-based or emulsion-based pressure-sensitive adhesive directly to a substrate and drying it, and applying these pressure-sensitive adhesives to release paper to form a pressure-sensitive adhesive layer in advance. In addition, a method of attaching the pressure-sensitive adhesive layer to the composite film can be applied. As a coating method, a rolling method such as a calender roll method or a coating method such as a doctor blade method or a gravure roll coater method can be employed.

  The protective pressure-sensitive adhesive sheet of the present invention can have a fluorine-containing polymer layer (coat layer) on the other surface of the substrate, that is, the surface on the side where the pressure-sensitive adhesive layer is not provided. This fluorine-containing polymer layer is formed using, for example, vinylidene difluoride (PVDF), a fluoroethylene vinyl ether copolymer, or the like. Examples of commercially available fluoroethylene vinyl ether copolymers include “Lumiflon” manufactured by Asahi Glass Co., Ltd.

  The fluorine-containing polymer layer may be, for example, a solution obtained by dissolving a fluorine-containing polymer in an appropriate solvent may be directly applied on a substrate and dried, or a release treatment surface of a polyethylene terephthalate (PET) film subjected to a release treatment. Further, after the solution is applied and dried, a mixture containing a urethane polymer and an acrylic monomer is applied thereon as a base material layer, and cured by irradiation with ultraviolet rays or the like.

  It is preferable that the thickness of a fluorine-containing polymer layer is 2-50 micrometers, More preferably, it is 5-40 micrometers, More preferably, it is 8-30 micrometers. If the thickness of the fluorine-containing polymer layer is 2 μm or more and 50 μm or less, defect sites such as pinholes are not generated, and the characteristics of the coating layer can be sufficiently exhibited.

  The protective pressure-sensitive adhesive sheet of the present invention is required to be transparent in order to reflect the color or the like of the painted surface of the adherend to the appearance as it is, but the same color as the color of the painted surface using a pigment or the like. It may be used as a paint substitute adhesive sheet by coloring with a different color.

  In the protective adhesive sheet of the present invention, an application sheet can be used for, for example, sticking positioning in order to improve the operation of attaching the adhesive sheet for protecting a coating film.

  The manufacturing method of the protective adhesive sheet of this invention is described below. For example, first, a coating solution for a composite film is applied to the release-treated surface of a release-treated polyethylene terephthalate film (temporary support 1), a transparent separator or the like is placed thereon, and ultraviolet rays or the like are irradiated from above. Then, a cross-linking point is also formed while forming the composite film, and then the separator is removed. Separately, a pressure-sensitive adhesive layer coating solution is applied to the release-treated surface of the release-treated polyester film (temporary support 2) to form a pressure-sensitive adhesive layer. Thereafter, this pressure-sensitive adhesive layer can be superimposed on the composite film surface to obtain a protective pressure-sensitive adhesive sheet. In addition, although it is the layer structure of the polyethylene terephthalate film (temporary support body 1) / composite film / adhesive layer / release polyester film (temporary support body 2) by which the peeling process was carried out here, this temporary support Since the body 1 and the temporary support 2 are peeled and removed at the time of use, that is, when the pressure-sensitive adhesive sheet is applied and applied, they are not particularly included in the configuration of the pressure-sensitive adhesive sheet for protecting a coating film of the present invention. However, these temporary support 1, temporary support 2 and the like can be appropriately provided as necessary, and these configurations belong to the technical scope of the present invention.

The protective pressure-sensitive adhesive sheet of the present invention has high strength and the like, and is excellent in flexibility with respect to a curved surface. Furthermore, the protective pressure-sensitive adhesive sheet of the present invention is also excellent in weather resistance. Therefore, it is suitable for a protective adhesive sheet for protecting a painted surface of an automobile, an aircraft, etc., for example, it can be satisfactorily applied to an adherend such as a painted surface of an automobile or a building, and is excellent. Chipping resistance can be exhibited, and yellowing hardly occurs even when used outdoors for a long time.

  EXAMPLES The present invention will be described in detail below using examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, parts mean parts by weight and% means% by weight. The measurement methods and evaluation methods used in the following examples are shown below.

(Measurement method and evaluation method)
(1) Measurement of water absorption rate A test piece having a size of 3 cm × 3 cm is cut out from the base material (with temporary support 1). After removing the temporary support 1 from the test piece and drying at 130 ° C. for 2 hours, the weight of the substrate (initial substrate weight) was measured. Next, this was immersed in warm water of 40 ° C. for 24 hours, and then the weight of the base material (base material weight after immersion) was measured. The measured value was substituted into the following formula to determine the water absorption rate.

Water absorption rate (%) =
{(Base material weight after immersion in warm water−initial base material weight) / initial base material weight} × 100

(2) Upper yield point temperature and breaking strength The substrate (with temporary support 1) was immersed in warm water at 40 ° C. for 24 hours. Thereafter, the base material is taken out, a paper cloth is lightly pressed on the surface to remove water droplets adhering to the surface, and then cut into a size of 1 cm wide × 13 cm long (sample), and the temporary support 1 is removed. A tensile test was conducted. That is, a tensile test was performed in an atmosphere of air temperature (23 ° C.) and relative humidity (50%) at a tensile speed of 200 mm / min and a distance between chucks of 50 mm. The upper yield point stress was determined from the obtained stress-strain curve.
Further, the sample obtained in the same manner was allowed to stand for 24 hours in an atmosphere of air temperature (23 ° C.) and relative humidity (50%), and then the temporary support 1 was removed, and the tensile speed was 200 mm / min. A tensile test was performed at a distance of 50 mm, and the force when the substrate broke was determined.

(3) Evaluation of chipping resistance A size of 6 cm × 13 cm was cut out from the protective adhesive sheet, the temporary support 1 and the temporary support 2 were removed, and a white coated plate having a size of 7 cm × 15 cm (Nippon Test Panel) A 2 kg roller was reciprocated once and attached to a dull steel plate “JIS-G3141” manufactured by the company, and bonded. This was allowed to stand for 24 hours in an atmosphere having an air temperature of 23 ° C. and a relative humidity of 50%, and then the chipping resistance was evaluated. That is, using a stepping stone tester, basalt 6 (500 g) was collided at a distance of 30 cm and an injection pressure of 0.45 MPa in an atmosphere of −10 ° C., and the presence or absence of scratches on the surface of the coated plate was visually observed. The case where no scratches were observed on the surface of the painted plate was indicated by the symbol “◯”, and the case where scratches were observed was indicated by the symbol “X”.

(4) Evaluation of weather resistance (yellowing resistance) A size of 4 cm × 4 cm is cut out from the protective adhesive sheet, the temporary support 1 and the temporary support 2 are removed, and a white coated plate having a size of 7 cm × 15 cm. A 2 kg roller is reciprocated once and attached to Japan Test Panel Co., Ltd. (dull steel plate “JIS-G3141” white acrylic), and left to stand at 23 ° C. for 24 hours, followed by a sunshine carbon weather test. Irradiation with a machine (manufactured by Suga Test Instruments Co., Ltd.) for 1,000 hours based on JIS-D2050 This air temperature 23 ° C., in an atmosphere of 50% relative humidity, the color difference meter (X-Rite Co. multiangle spectrophotometer MA68II), light receiving angle of 15 °, viewing conditions ^D65 10 ^L * ^a * b ^* Measured in the color system. That is, b ^* (before) weather resistance promotion and b ^* (after) weather resistance promotion are measured, and Δb ^* (= b ^* (after) −b ^* ( Before)). The larger the value of b ^* is, the more yellow it is. The larger the value of Δb ^* is, the more yellow it is after weather resistance is promoted.

Example 1
<< Preparation of coating solution for composite film >>
A monofunctional acrylic monomer having 1 part of acrylic acid (AA) and a glass transition temperature (Tg) of a homopolymer of 0 ° C. or higher as a acrylic monomer in a reaction vessel equipped with a condenser, a thermometer, and a stirrer As a monofunctional acrylic monomer having 79 parts of isobornyl acrylate (IBXA) (Tg = 94 ° C.) and a glass transition temperature (Tg) of the homopolymer of less than 0 ° C., n-butyl acrylate (BA) (Tg = -54 ° C) and 20 parts of polyol, and 72.8 parts of polyoxytetramethylene glycol (PTMG) (number average molecular weight 650, manufactured by Mitsubishi Chemical Co., Ltd.) as a polyol were added while stirring. 27.2 parts of xylylene diisocyanate (HXDI) was dropped and reacted at 65 ° C. for 10 hours to obtain a urethane polymer-acrylic monomer mixture.

  Thereafter, 6 parts of trimethylolpropane triacrylate as a crosslinking agent and bis (2,4,6-trimethylbenzoyl) phenyl-phosphine oxide (“IRGACURE 819” manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator 0.3 part of an ultraviolet absorber, 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and oxirane [(C10 -C16, mainly C12-C13 alkyloxy) methyloxirane] and 1-methoxy-2-propanol UV absorber ("TINUVIN 400" manufactured by Ciba Specialty Chemicals Co., Ltd.) 2.5 parts, and bis (2,2,6,6-tetradecanedioic acid) as a light stabilizer 2.5 parts of methyl-1- (octyloxy) -4-piperidinyl) ester, reaction product of 1,1-dimethylethyl hydroperoxide and octane (“TINUVIN 123” manufactured by Ciba Specialty Chemicals) By addition, a mixture of urethane polymer and acrylic monomer (composite film coating solution) was obtained. However, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.25.

<Production of base material>
On the polyethylene terephthalate (PET) film (thickness 75 μm) obtained by removing the prepared urethane polymer-acrylic monomer mixture (coating liquid for composite film) as a temporary support 1, the thickness after curing is 300 μm. Applied. A PET film peel-treated as a separator is overlaid thereon, and the PET film surface is cured by irradiating with ultraviolet rays (illuminance 290 mW / cm ² , light amount 4,600 mJ / cm ² ) using a metal halide lamp, and temporarily supported. A composite film was formed on the body 1. Thereafter, the coated PET film (separator) was removed and dried at 140 ° C. for 3 minutes to remove the unreacted residual acrylic monomer to obtain a substrate (with temporary support 1).

<< Production of adhesive layer >>
To a mixture of 90 parts of 2-ethylhexyl acrylate and 10 parts of acrylic acid as a monomer component, 0.05 part of a trade name “Irgacure 651” (manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator, After blending 0.05 parts of the name “Irgacure 184” (manufactured by Ciba Specialty Chemicals), until the viscosity is about 15 Pa · s (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) An acrylic composition (UV syrup) partially polymerized by irradiation with ultraviolet rays was prepared.

  0.08 part of 1,6-hexanediol diacrylate with respect to 100 parts of the obtained UV syrup, a hindered phenol type antioxidant (trade name “Irganox 1010” manufactured by Ciba Specialty Chemicals) Was added to prepare a pressure-sensitive adhesive composition.

This pressure-sensitive adhesive composition was applied to the release-treated surface of a 38 μm-thick polyester film as the temporary support 2 so that the final product had a thickness of 50 μm.
On top of this, a peel-treated PET film as a separator is overlaid and coated, and then the surface of the PET film is cured by irradiating with ultraviolet rays (illuminance 290 mW / cm ² , light amount 4,600 mJ / cm ² ) using a metal halide lamp. Thus, an adhesive layer was formed on the temporary support 2 (layer structure: temporary support 2 / adhesive layer / separator). Then, it was made to dry at 140 degreeC for 3 minute (s), the unreacted residual acrylic monomer was dried, and the adhesive layer was produced.

<Production of adhesive sheet>
The separator was removed, and the pressure-sensitive adhesive sheet for protection (layer structure of temporary support 1 / composite film / pressure-sensitive adhesive layer / temporary support 2) was prepared by laminating the pressure-sensitive adhesive layer so as to overlap the obtained base material surface. .

<Measurement and evaluation>
About the obtained adhesive sheet, according to the evaluation and the measuring method shown above, the water absorption was measured, the upper yield point stress and the breaking strength were measured, the chipping resistance was evaluated, and the weather resistance was evaluated. The results are shown in Table 1.

(Examples 2-3 and Comparative Examples 1-2)
In preparation of a mixture of urethane polymer and acrylic monomer (coating solution for composite film), except for changing the number of blended parts of each component (acrylic acid, IBXA, n-BA, PTMG, HXDI) to those shown in Table 1. A protective adhesive sheet was produced in the same manner as in Example 1.
The obtained pressure-sensitive adhesive sheet was measured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
A non-yellowing type urethane film (thickness: 300 μm) was obtained from a commercial product. A protective adhesive sheet was prepared in the same manner as in Example 1 except that this urethane film was used instead of the composite film.
About the obtained adhesive sheet for protection, the same measurement and evaluation as Example 1 were performed. The results are shown in Table 1.

As is apparent from Table 1, the protective adhesive sheets of Examples 1 to 3 have an upper yield point stress after immersion in the range of 1.0 MPa to 5.0 MPa, and the breaking strength in the range of 10 MPa to 100 MPa. In the evaluation of chipping resistance, it was found to be “◯”. Moreover, the value of Δb ^* was small, and it was found that the weather resistance was excellent. Therefore, these protective adhesive sheets do not turn yellow even when exposed to ultraviolet rays for a long time, and can be used outdoors for a long time. In Comparative Example 3 using a commercially available urethane film, although yellowing is severe and weather resistance is poor, Examples 1 to 3 satisfying the constituent requirements of the present invention are markedly higher than conventional products. It was found that the weather resistance was improved.
Moreover, since Examples 1-3 are equipped with the composite film containing a urethane polymer and an acryl-type polymer, they are excellent also in intensity | strength, a softness | flexibility, etc., and fully follow a to-be-adhered body, for example, the body curved surface of a motor vehicle. be able to.

  On the other hand, the comparative example 1 which does not use an acrylic acid monomer is inferior in breaking strength and chipping resistance, and the comparative example 2 in which the amount of acrylic acid monomer used exceeds the range of the present invention has a water absorption of 5 %, Yield stress was low, and chipping resistance was inferior. That is, it has been found that those not having the configuration of the present invention cannot satisfy the practical level of at least one of the chipping resistance and the weather resistance.

  The protective pressure-sensitive adhesive sheet of the present invention can be suitably used as a pressure-sensitive adhesive sheet that requires flexibility to a curved surface or the like. In addition, the protective pressure-sensitive adhesive sheet of the present invention is excellent in weather resistance. For example, even if it is used outdoors for a long time, it will not be colored or lose its glossiness, so that it is exposed to the outdoor weather. It can be used as an adhesive sheet for protecting the coating film surface. Moreover, it is suitable also as an adhesive sheet for protecting the coating film of a motor vehicle.

Claims (7)

  In the protective adhesive tape having a base material and an adhesive layer on one side of the base material, the base material is a composite film made of a mixture containing an acrylic polymer and a urethane polymer, and the acrylic polymer is an acrylic film An acrylic component comprising an acid monomer, a monofunctional acrylic monomer having a homopolymer glass transition temperature (Tg) of 273 K or higher, and a monofunctional acrylic monomer having a homopolymer glass transition temperature (Tg) of less than 273 K The acrylic monomer content in the acrylic component is 1% by weight or more and 30% by weight or less, the urethane polymer is composed of diol and diisocyanate, and the urethane polymer is NCO / OH (equivalent ratio) = 1.1 to 2.0, and the composite film is N, N-dimethyl Formamide (DMF) protecting adhesive tape characterized by having a soluble matter.   The protective adhesive tape according to claim 1, wherein the composite film has a gel fraction of 50% or more and 99.5% or less.   The composite film uses the acrylic component as a solvent, forms a urethane polymer by thermally polymerizing the diol and the diisocyanate in the solvent, forms a sheet by adding a photopolymerization initiator, and then irradiates with ultraviolet rays. The protective pressure-sensitive adhesive sheet according to claim 1, wherein the protective pressure-sensitive adhesive sheet is obtained as described above.   The protective adhesive tape according to any one of claims 1 to 3, wherein the composite film has a water absorption of 4% or less.   The pressure-sensitive adhesive layer comprises an adhesive containing as a main component at least one selected from the group consisting of 2-ethylhexyl acrylate and isononyl acrylate and at least one selected from the group consisting of acrylic acid and methacrylic acid. The protective pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein the protective pressure-sensitive adhesive tape is provided.   The substrate has a fluorine-containing polymer layer on one surface of the composite film, and the fluorine-containing polymer layer is disposed on a surface opposite to the surface on which the pressure-sensitive adhesive layer is provided. The protective pressure-sensitive adhesive tape according to claim 1, wherein the protective pressure-sensitive adhesive tape is provided.   The protection according to any one of claims 1 to 6, wherein the protective pressure-sensitive adhesive sheet is used by being adhered to at least one exterior coating film surface selected from the group consisting of automobiles and aircraft. Adhesive sheet.