JP2006045250A - Base film for marking sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base film for marking sheets having very high practicality since it is excellent in curved surface followability and tearing strength, and particularly excellent in appearance and stiffness. <P>SOLUTION: The base film for marking sheets comprises a polyurethane resin obtained by subjecting an isocyanate group-containing urethane prepolymer obtained by reacting an acrylic polyol, a polycarbonate diol, a polyether polyol and an organic diisocyanate to chain-extending reaction using a chain extender, wherein a polyisocyanate curing agent is optionally further reacted therewith. The content of the acrylic polyol is 20-80 mass%, and the mass ratio of the polycarbonate diol to the polyether polyol is 20/80-80/20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has basic characteristics necessary for a marking sheet such as curved surface followability and strength, and further has excellent physical properties such as thermal dimensional stability and appearance, and is used for marking sheets used for decoration and display. Related to base film.

Conventionally, for advertisements such as signboards and show windows, vehicles (for example, automobiles, motorcycles), ships (for example, motor boats), household and industrial electrical appliances, traffic and road signs, information boards, etc. Marking sheets are widely used for display and the like.
Various types of marking sheets have been proposed so far depending on the purpose and application, but basically a structure in which an adhesive layer and a release agent layer are laminated in this order on a base film.
Specifically, for example, as this base film, a resin composition comprising at least one of acrylic polyol (A), polyether polyol, polyester polyol, polycarbonate polyol, and polybutadiene polyol (B), and polyisocyanate compound (C). Has been proposed (see, for example, Patent Document 1).
JP 2001-213932 A

  However, it is described that the sheet having a cured resin layer of the resin composition of Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-213932) is tough and excellent in extensibility, molding processability, weather resistance, and chemical resistance. However, it is still difficult to say that it satisfies the required characteristics of the recent and advanced marking sheets that are diverse and sophisticated.

  An object of the present invention is to provide a base film for a marking sheet that has a very good practicality and a strong appearance, in addition to curved surface followability and tear strength.

  In order to achieve the above object, the present invention provides an isocyanate group-containing urethane prepolymer obtained by reacting an acrylic polyol (A), a polycarbonate polyol (B), a polyether polyol (C), and an organic polyisocyanate (D). Is a base film for a marking sheet made of a polyurethane resin obtained by chain extension reaction with a chain extender, wherein the content of acrylic polyol (A) in the polyurethane resin is 20 to 80% by mass, and The base film for a marking sheet, wherein a mass ratio of the polycarbonate polyol (B) and the polyether polyol (C) is 20/80 to 80/20.

  In the present invention, an isocyanate group-containing urethane prepolymer obtained by reacting an acrylic polyol (A), a polycarbonate polyol (B), a polyether polyol (C), and an organic polyisocyanate (D) is chain extended with a chain extender. A marking sheet base film obtained by further reacting a polyisocyanate curing agent with the polyurethane resin obtained by the reaction, wherein the content of the acrylic polyol (A) in the polyurethane resin is 20 to 80% by mass, And it is the said base film for marking sheets characterized by the mass ratio of polycarbonate polyol (B) and polyether polyol (C) being 20 / 80-80 / 20.

  The polyurethane resin in the present invention has high bending resistance and tear strength, and not only has excellent curved surface followability according to various shapes of the object to be coated, but also has weather resistance, yield strength and thermal dimensional stability. Especially expensive. For this reason, the polyurethane resin film of the present invention, in addition to the basic properties essential to the film, has a particularly good appearance, strong waist and excellent workability. It has become possible to provide a base film for a marking sheet that sufficiently satisfies the demanded and advanced characteristics and is extremely practical.

Hereinafter, the present invention will be described in detail.
First, the raw material used for manufacture of the polyurethane resin in this invention is demonstrated.
The acrylic polyol (A) used in the present invention is suitably obtained by a copolymerization reaction between an active hydrogen group and unsaturated double bond-containing compound and an unsaturated double bond-containing compound not containing an active hydrogen group.
Examples of the compound containing an active hydrogen group and an unsaturated double bond include 2-hydroxyethyl acrylate, hydroxypropyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, ε-caprolactone adduct of 2-hydroxyethyl acrylate, 2-hydroxyethyl Β-methyl-γ-valerolactone adduct of acrylate, acrylates such as glycerol monoacrylate, glycerol diacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, 2-hydroxyethyl methacrylate Ε-caprolactone adduct of 2-hydroxyethyl methacrylate β-methyl- Examples include γ-valerolactone adducts, methacrylates such as glycerol monomethacrylate and glycerol dimethacrylate, and allyl compounds such as allyl alcohol, glycerol monoallyl ether, and glycerol diallyl ether.
Any of these may be used alone or in admixture of two or more.
Among these, 2-hydroxyethyl acrylate, ε-caprolactone adduct of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, ε-caprolactone adduct of 2-hydroxyethyl methacrylate, or a mixture of any two or more thereof. Furthermore, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate or a mixture thereof is more preferable.
Examples of unsaturated double bond-containing compounds that do not contain an active hydrogen group include alkyl acrylates, cycloalkyl acrylates, phenyl acrylates, benzyl acrylates, glycidyl acrylates and other acrylic esters, alkyl methacrylates, cyclomethacrylates Methacrylic esters such as alkyl, phenyl methacrylate, benzyl methacrylate and glycidyl methacrylate, vinyl ester compounds such as vinyl acetate and vinyl propionate, vinyl alkyl ethers such as vinyl methyl ether, vinyl cyclohexyl ether, vinyl phenyl ether , Vinyl ether compounds such as vinyl benzyl ether and vinyl glycidyl ether, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, styrene, vinyl toluene, α Aromatic compounds containing ethylenically unsaturated double bonds such as methylstyrene, vinyl halides such as vinyl chloride and vinyl bromide, vinylidene halides such as vinylidene chloride and vinylidene bromide, and maleic acid such as dialkyl maleate Diesters, fumaric acid diesters such as dialkyl fumarate, itaconic acid diesters such as dimethyl itaconate, dialkylacrylamides such as N, N-dimethylacrylamide, heterocyclic vinyl compounds such as N-vinylpyrrolidone and 2-vinylpyridine And the like.
Any of these may be used alone or in admixture of two or more.
Of these, methyl acrylate, methyl methacrylate or mixtures thereof are preferred.

The acrylic polyol (A) preferably has a hydroxyl value of 3 to 12 mgKOH / g, more preferably 3.5 to 11.5 mgKOH / g, and an average functional group number of 1 to 2, and more preferably 1.5 to 2. When the hydroxyl value exceeds the upper limit, the resulting polyurethane resin becomes too hard and the flexibility such as flexibility tends to be lowered. Moreover, when less than a minimum, the intensity | strength of the polyurethane resin obtained falls easily. When the average functional group number is less than the lower limit, the molecular weight of the resulting polyurethane resin tends to be small, and the strength tends to be insufficient. Moreover, when exceeding an upper limit, it will become easy to gelatinize at the time of manufacture of a polyurethane resin.
The number average molecular weight of the acrylic polyol (A) is preferably 500 to 30,000, more preferably 1,000 to 10,000, and particularly preferably 1,000 to 3,000.

  Content of an acrylic polyol (A) is 20-80 mass% in a polyurethane resin, 30-70 mass%, Furthermore, 40-60 mass% is preferable. When the content of the acrylic polyol (A) is less than the lower limit, the weather resistance of the resulting polyurethane resin is deteriorated, and the yield strength and thermal dimensional stability are also reduced. Moreover, when exceeding an upper limit, the tear strength and bending resistance of the polyurethane resin obtained will fall.

The polycarbonate polyol (B) used in the present invention is suitably obtained by a dehydrochlorination reaction between a short-chain polyol and phosgene or a transesterification condensation reaction with a low-molecular carbonate such as dialkyl carbonate, alkylene carbonate or diaryl carbonate. It is done.
Examples of the short-chain polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentane. Diol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, dimethylolheptane, diethylene glycol , Dipropylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A ethylene oxide and propylene oxide adducts, etc. Less than 500 Thing, and the like.
Examples of the dialkyl carbonate include dimethyl carbonate and diethyl carbonate.
Examples of the alkylene carbonate include ethylene carbonate and propylene carbonate.
Examples of the diaryl carbonate include diphenyl carbonate.
Any of these may be used alone or in admixture of two or more.
Among these, a polycarbonate polyol obtained from an aliphatic diol having 1 to 8 carbon atoms, particularly a polycarbonate polyol obtained from 3-methyl-1,5-pentanediol, 1,6-hexanediol or a mixture thereof is preferable.

The polycarbonate polyol (B) preferably has a hydroxyl value of 20 to 250 mgKOH / g, more preferably 25 to 225 mgKOH / g, and an average functional group number of 1 to 3, and more preferably 1.8 to 2.5. When the hydroxyl value exceeds the upper limit, the resulting polyurethane resin tends to be too hard. Moreover, when less than a minimum, the intensity | strength of the polyurethane resin obtained falls easily. When the average functional group number is less than the lower limit, the molecular weight of the resulting polyurethane resin tends to be small, and the strength tends to be insufficient. Moreover, when exceeding an upper limit, it will become easy to gelatinize at the time of manufacture of a polyurethane resin.
The number average molecular weight of the polycarbonate polyol (B) is preferably 500 to 5,000, more preferably 800 to 4,000.

Preferred examples of the polyether polyol (C) used in the present invention include those obtained by ring-opening addition polymerization of alkylene oxide, those obtained by ring-opening addition polymerization of alkylene oxide in an initiator, and the like.
As initiators, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, sorbitol, shoe Short chain polyols such as claus, glucose, lactose and sorbitan, low molecular weight polyphenols such as bisphenol A and bisphenol F, short chain diamines such as ethylenediamine and butylenediamine, low molecular amino alcohols such as monoethanolamine and diethanolamine, adipine Low molecular weight polycarboxylic acid such as acid, terephthalic acid, low molecular weight polyoxyalkylene polyol obtained by reacting at least one of these with alkylene oxide Etc. The.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran.
That is, as the polyether polyol (C), specifically, polyoxyethylene polyol, polyoxypropylene polyol, polytetramethylene ether polyol, poly (oxyethylene) -poly (oxypropylene) -random or block copolymer polyol , Poly (oxypropylene) -poly (oxybutylene) -random or block copolymer polyol.
Any of these may be used alone or in admixture of two or more.
Of these, polyoxypropylene polyol is preferred.

  The polyether polyol (C) preferably has a number average molecular weight of 500 to 100,000, more preferably 700 to 30,000, and particularly preferably 800 to 10,000 for reasons such as good workability. Two or more, more preferably 2 to 4, particularly 2 are preferred.

  In the present invention, the mass ratio of the polycarbonate polyol (B) and the polyether polyol (C) is (B) / (C) = 20/80 to 80/20, and (B) / (C) = 30 / 70-70 / 30 is preferable. When there is more polyether polyol (C) than the said ratio, the yield point strength and thermal dimensional stability of the polyurethane resin obtained will fall easily. When the amount of the polycarbonate polyol (B) is large, the glass transition point is increased more than necessary and becomes hard, the elongation is small, cracks are likely to occur at the curved portion, and the tear strength is deteriorated.

Examples of the organic polyisocyanate (D) used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2 '-Diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 1,4-naphthylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, tetra Methylxylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-di Aromatic diisocyanates such as socyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, 4,4′-diphenylpropane diisocyanate, 3,3′-dimethoxydiphenyl-4,4′-diisocyanate, tetramethylene diisocyanate, Hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate, aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated Tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, cyclo Alicyclic diisocyanates such as xyl diisocyanate, urethane modified products, allophanate modified products, urea modified products, biuret modified products, uretdione modified products, uretoimine modified products, isocyanurate modified products, carbodiimide modified products of these organic diisocyanates, etc. Can be mentioned.
Any of these may be used alone or in admixture of two or more.
Among these, from the viewpoints of physical properties and weather resistance of the obtained polyurethane resin, aliphatic diisocyanate, alicyclic diisocyanate or a mixture thereof, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate or A mixture of any two or more of these is preferable.

As the chain extender used in the present invention, those having a molecular weight of less than 500, such as a short-chain polyol, a short-chain diamine, and a low-molecular amino alcohol can be preferably exemplified, and a short-chain diamine having a molecular weight of less than 500 is more preferred. It is. Due to the cohesive strength derived from intramolecular and intermolecular hydrogen bonds of the urea bonds generated by chain extension reactions using short-chain diamines, as well as weather resistance and stain resistance, the waist of the film (bending point strength) Mechanical properties such as tear strength are improved. In addition, excellent mechanical properties can be secured while maintaining flexibility such as flex resistance and curved surface followability of the film by urea bonding.
As a short chain polyol, what is used for manufacture of the above-mentioned polycarbonate polyol (B) is mentioned.
Short chain diamines include ethylenediamine, propylenediamine, hexamethylenediamine, hydrazine, piperazine, cyclohexanediamine, isophoronediamine, 2,2,4-trimethylhexamethylenediamine, cyclohexanediamine, dicyclohexylmethane-4,4'-diamine, and the like. Can be mentioned.
Examples of the low molecular amino alcohol include monoethanolamine and diethanolamine.
Any of these may be used alone or in admixture of two or more.
Of these, isophoronediamine, monoethanolamine, or a mixture thereof is preferred because of its slow reaction with isocyanate groups.

Next, the production of the polyurethane resin in the present invention will be described.
The polyurethane resin in the present invention can be preferably produced by reacting the raw materials in an organic solution. Specifically, for example, first, acrylic polyol (A), polycarbonate polyol (B), and polyether polyol (C) are appropriately diluted with an organic solvent. After adding organic polyisocyanate (D) to this solution and adding a urethanization catalyst as needed, it is made to react at reaction temperature 30-100 degreeC and also 50-80 degreeC for several hours, and isocyanate group containing urethane prepolymer is carried out. A polymer can be suitably synthesized. In this case, the charged molar ratio (R value) of isocyanate group / hydroxyl group is preferably 1.1 to 2.5, and particularly preferably 1.5 to 2.5. When the R value is less than 1.1, the weather resistance and mechanical properties of the finally obtained polyurethane resin tend to be lowered. Moreover, when R value exceeds 2.5, it is easy to gelatinize at the time of manufacture of the polyurethane resin finally obtained.
Next, a chain extender or preferably a reaction terminator, which will be described later, is further added to the obtained isocyanate group-containing urethane prepolymer so that the isocyanate group disappears at a reaction temperature of 30 to 80 ° C., further 30 to 50 ° C. By subjecting it to chain extension reaction, the desired polyurethane resin can be suitably obtained. In this case, the charged molar ratio (R value) of isocyanate group / active hydrogen group is preferably 0.9 to 1.1, particularly preferably 0.95 to 1.05.

  In addition, the polyurethane resin in the present invention can also be produced by using a mixing and kneading apparatus such as a reaction kettle or kneader equipped with a stirring device, a uniaxial or multiaxial extrusion reaction apparatus, and the like.

  Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as pentane, hexane, and octane, alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, and methylcyclohexane, acetone , Ketone solvents such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, ether solvents such as diethyl ether, 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, Cellosolve solvents such as propylene glycol dimethyl ether and propylene glycol monomethyl ether acetate, ester solvents such as ethyl acetate and butyl acetate, dimethyl Formamide, dimethyl acetamide, etc. aprotic polar solvent such as N- methylpyrrolidone, not particularly limited as long as the isocyanate group inert. An alcohol solvent such as isopropanol can also be suitably used.

  Specific examples of the urethanization catalyst include organic metal compounds such as dibutyltin dilaurate and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof.

The reaction terminator can facilitate control of the (number average) molecular weight of the polyurethane resin in the production of the polyurethane resin, and can shorten the production time.
Examples of the reaction terminator include monoisocyanates such as phenyl isocyanate, monoalcohols such as methanol, ethanol and isopropanol, monoamines such as ethylamine, propylamine, diethylamine and dibutylamine, monoethanolamine, diethanolamine, N- Examples include amino alcohols such as methylethanolamine, monopropanolamine, and dipropanolamine.
Any of these may be used alone or in admixture of two or more.
Among these, one or any two or more selected from amino alcohol, monoethanolamine, dietaethanolamine, monopropanolamine, and dipropanolamine are preferable. This is because the hydroxyl group can be introduced into the terminal of the polyurethane resin because the reactivity with the isocyanate group is larger in the amino group than in the hydroxyl group.
The terminal hydroxyl group of the polyurethane resin is involved in the curing reaction when a polyisocyanate curing agent is further blended.

  The number average molecular weight of the polyurethane resin thus obtained is preferably 8,000 to 100,000, more preferably 10,000 to 50,000, as measured by gel permeation (GPC) using a polystyrene calibration curve. When the number average molecular weight is less than the lower limit, the weather resistance tends to decrease. When the number average molecular weight exceeds the upper limit, the pigment dispersibility and workability are likely to deteriorate.

  In addition, you may add antioxidant, a ultraviolet absorber, a ultraviolet stabilizer, etc. to the polyurethane resin in this invention before reaction after reaction, in order to maintain a weather resistance. In addition, pigments / dyes, dispersion stabilizers, silicon-based and amide-based tack inhibitors for reducing surface tack may be added.

The polyurethane resin in the present invention is preferably used in combination with a polyisocyanate curing agent in order to further improve weather resistance, thermal dimensional stability and the like. The addition amount is preferably 10 parts by mass or less, particularly 1 to 5 parts by mass with respect to 100 parts by mass of the polyurethane resin.
Examples of the polyisocyanate curing agent include Coronate (registered trademark) HX, Coronate HL, Coronate L, Coronate 2030, Coronate 2031 and the like manufactured by Nippon Polyurethane Industry Co., Ltd.
Any of these may be used alone or in admixture of two or more.
Of these, non-yellowing polyisocyanate curing agents such as Coronate HX and Coronate HL are preferable in consideration of weather resistance and the like.

Furthermore, manufacture of the marking sheet using the polyurethane resin in this invention is demonstrated.
First, the polyurethane resin in the present invention is applied on a release sheet, cured and formed into a film, thereby forming a base film. Examples of the release sheet include paper, plastic films such as polyester, polypropylene, polyethylene, and cellulose acetate, and metal foils such as aluminum and stainless steel, and those having a thickness of 10 to 250 μm are preferable.

Application of the polyurethane resin in the present invention is a conventionally known method, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade coating method, roll coating method, knife coating method, curtain coating method, A slot orifice method, a spray coating method, a bar coating method, or the like can be used. The polyurethane resin may be applied in several times or may be applied once. A plurality of different methods may be combined. The coating thickness of the polyurethane resin is usually 10 to 200 μm
However, it is not limited to this range, and it may be applied so as to have a film thickness suitable for the application and required performance. Curing of the polyurethane resin may be performed at a temperature and time according to the type of resin, the type of release sheet, the film thickness, and the use, and is usually performed at room temperature to 350 ° C. From the point of improvement, it is preferable to heat to 30 to 350 ° C.

A pressure-sensitive adhesive layer can be provided on one side or both sides of the marking sheet obtained in this manner, if necessary. At that time, the release sheet attached to the base film layer may be left as it is or may be peeled off. However, when the adhesive layer is provided on both sides, the release sheet is peeled off.
Examples of the adhesive include rubber-based adhesives mainly composed of general natural rubber, synthetic isoprene rubber, recycled rubber, styrene-butadiene rubber, polyisoprene rubber, styrene-isoprene-styrene rubber, and (meth) Acrylic pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive mainly composed of a polymer obtained by copolymerizing monomers such as acrylic acid, methacrylic acid, acrylamide, vinyl acetate, and styrene mainly composed of acrylic ester (C2 to C12) There may be mentioned, for example, an adhesive, and a material having an appropriate adhesive force according to the use and the material of the adherend can be selected.

  Depending on the type of adhesive and the coating suitability, the pressure-sensitive adhesive layer may be a conventionally known method such as a kiss coating method, a die coating method, a lip coating method, a comma coating method, a blade coating method, or a bar coating method. Utilizing it, it may be applied directly on the base film and laminated, or the adhesive once coated on the process paper may be laminated and laminated on the base film.

  Marking sheets obtained in this way are molded bodies and exterior panels for automobiles, motorcycles, motorboats, snowmobiles, home appliances, electronic devices, interior materials, building materials, various information boards, traffic signs, indoor / outdoor advertisements, signboards, Various decorations such as shutters and windows, coloring, display materials, as sheets that provide various surface functions such as weather resistance, antifouling properties, various resistances, etc. Or can be used as a packaging material for protecting each function. In particular, it is suitable for use in exterior applications that require high weather resistance.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not construed as being limited in any way by these examples. In each example, “%” is based on mass unless otherwise specified.

Example 1
[Production of polyurethane resin solution]
To a four-necked separable flask equipped with a stirrer with a torque meter, a thermometer, and a nitrogen gas inlet tube, a polycarbonate diol having a number average molecular weight of 1,000 (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name (registered trademark): NIPPOLAN 981) ) 58.3 g, polyoxypropylene diol having a number average molecular weight of 1,000 (manufactured by Sanyo Chemical Industries, Ltd., trade name (registered trademark): Sannics PP-1000), acrylic polyol (methyl methacrylate / 2- Hydroxyethyl methacrylate, hydroxyl value 5.6 mg KOH / g (in terms of solid content), toluene solution with a solid content of 40%, average functional group number 1.8) 437.2 g, hydrogenated xylylene diisocyanate (manufactured by Mitsui Takeda Chemical Co., Ltd.) Trade name: Takenate 600) 42.6 g, DBTDL 0.02 g, toluene 11. Charged g, to obtain an isocyanate group-containing acrylic urethane prepolymer solution and reacted for 6 hours under 75 ° C. nitrogen atmosphere.
After diluting this prepolymer solution with 226.6 g of toluene, an amine solution in which 150.0 g of IPA, 15.5 g of IPDA and 0.4 g of MEA were mixed was dropped into the stirring prepolymer solution to carry out a chain extension reaction. It was.
Thereafter, the reaction was continued at 50 ° C. until the peak of the isocyanate group by FT-IR disappeared to obtain a polyurethane resin solution PU-1 having a viscosity of 1200 mPa · s / 25 ° C. and a solid content of 35%.
[Manufacture of base film]
This polyurethane resin solution PU-1 was cast on a release paper with a bar coater so that the film thickness was 50 μm (dry), allowed to stand at room temperature for 10 minutes, and then dried and cured in a 120 ° C. oven for 60 minutes. A base film was obtained.
[Manufacture of marking sheets]
Using a comma coater, the coating thickness after drying the two-component cross-linking solvent-type acrylic resin-based adhesive on the release-treated surface of the release paper that has been release-treated with the silicone resin-based release agent is 40 μm Then, the laminate was coated and dried to prepare a laminate composed of an adhesive layer having a thickness of 40 μm and a release paper. Subsequently, it laminated | stacked and laminated | stacked using a part of base film obtained above on the adhesive layer side of this laminated body, and the marking sheet was obtained.
These results, base film and marking sheet property test results are shown in Table 1.

Examples 2-5, Comparative Examples 1-7
In the same procedure as in Example 1, polyurethane resin solutions PU-2 to 12 were obtained using the raw materials shown in Tables 1 and 2. Using these polyurethane resin solutions PU-2 to PU-12, a base film and a marking sheet were obtained in the same procedure as in Example 1.
These results and the base film and marking sheet property test results are shown in Tables 1 and 2.

In Examples 1-5, Comparative Examples 1-7 and Tables 1 and 2, Acrylic polyol: Methyl methacrylate / 2-hydroxyethyl acrylate acrylic polyol, hydroxyl value 5.6 mg KOH / g (solid content conversion), solid content 40% Toluene solution, average functional group number = 1.8
Polycarbonate diol: manufactured by Nippon Polyurethane Industry Co., Ltd., trade name (registered trademark): Nipponran 981, number average molecular weight 1,000
Polyoxypropylene diol: manufactured by Sanyo Chemical Industries, Ltd., trade name (registered trademark): SANNICS PP-1000, number average molecular weight 1,000
DBTDL: Dibutyltin dilaurate IPDA: Isophoronediamine MEA: Monoethanolamine IPA: Isopropanol

[Base film characteristics]
The performance of the base film was evaluated by the following method.
(1) Yield point strength Measured according to the method of JIS K6251.
Evaluation criteria: ○: Yield point strength 15 MPa or more
X: Yield point strength less than 15 MPa (2) Tear strength Measured and evaluated by JIS K7128-1 trouser tear method.
Evaluation criteria: ○: Tear strength 3.0 N / mm or more
X: Tear strength less than 3.0 N / mm (3) Weather resistance Measured according to the method of JIS K6266.
Evaluation criteria: ○: Good appearance
Δ: Some change in appearance
X: Remarkable appearance change (4) Bending resistance A base film was wound around a rod having a diameter of 1 mm, and the presence or absence of cracks was visually evaluated.
Evaluation criteria: ○: No cracks are observed
X: Cracks observed (5) Thermal dimensional stability Measured according to the method of JIS K7133, and the expansion / contraction rate (%) was calculated and evaluated according to the following formula.
S = (L ₁ −L ₀ ) / L ₀ × 100
However, S: Expansion rate (%)
L ₀ : Length before heat treatment (mm)
L ₁ : Length after heat treatment (mm)
Evaluation criteria; A: S = less than ± 1.0%
○: S = ± 1.0% or more and less than ± 2.0%
×: S = ± 2.0% or more

[Characteristics of marking sheet]
The performance of the marking sheet was evaluated by the following method.
(1) Cutting property Using a cutting machine (trade name “CG45”, manufactured by MIMAKI), the marking sheet was cut, and cut property was evaluated according to the following three-point evaluation criteria.
Evaluation criteria; 3 points: We were able to cut without problems
2 points: A part of the curl due to poor sheet cutting occurred at an acute angle.
1 point: There was a noticeable wrinkle due to sheet cutting failure at an acute angle (2) Workability The release sheet of the marking sheet was peeled off, and the adhesive sheet side of the marking sheet was placed on the peak of the corrugated plate having a cubic surface Adhere, and then press the corrugated plate into the trough of the corrugated plate using a special construction tool, leave it in an atmosphere of 23 ° C. for 3 days, and then visually observe the marking sheet floating state. The workability was evaluated according to the evaluation criteria.
Evaluation criteria: 5 points: No floating occurred in the valley
4 points: Marking sheet tears partially when pushed into valley
3 points: Some lift occurred in the valley
2 points: Marking sheet tearing occurred when pushed into valley
1 point: Remarkable floating occurred in the valley (3) Weather resistance After the marking sheet was exposed for 2000 hours with a carbon arc sunshine type weatherometer, before and after the accelerated exposure using a spectrocolorimeter “CM-3700d” The color difference of was measured.
Evaluation criteria: 3 points: Color difference is 6 or less (good)
2 points: Color difference of more than 6 to 8 or less (possible)
1 point: Color difference is 8 or more (impossible)

Examples 6-10
A base film and a marking sheet were obtained in the same procedure as in Example 1 using the polyurethane resin solutions PU-1 to PU-5 and the polyisocyanate curing agent shown in Table 3.
Table 3 shows these results and the base film and marking sheet property test results.

Claims (2)

An isocyanate group-containing urethane prepolymer obtained by reacting an acrylic polyol (A), a polycarbonate polyol (B), a polyether polyol (C), and an organic polyisocyanate (D) is subjected to a chain extension reaction with a chain extender. A marking sheet base film made of a polyurethane resin,
The content of the acrylic polyol (A) in the polyurethane resin is 20 to 80% by mass, and the mass ratio of the polycarbonate polyol (B) to the polyether polyol (C) is 20/80 to 80/20. The marking film base film. Obtained by subjecting an isocyanate group-containing urethane prepolymer obtained by reacting acrylic polyol (A), polycarbonate polyol (B), polyether polyol (C), and organic polyisocyanate (D) to a chain extension reaction with a chain extender. A base film for a marking sheet obtained by further reacting a polyurethane resin with a polyisocyanate curing agent,
The content of the acrylic polyol (A) in the polyurethane resin is 20 to 80% by mass, and the mass ratio of the polycarbonate polyol (B) to the polyether polyol (C) is 20/80 to 80/20. The marking film base film.