JP2000010485A - Thermosensitive recording label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosensitive recording label which has good adhesion property to a polyolefin wrapping film and which does not cause decrease in recording sensitivity or white voids in prints. SOLUTION: This thermosensitive recording label is produced by laminating a thermosensitive recording body, an adhesive layer and release paper. An adhesive which forms the adhesive layer is a water dispersion type adhesive containing 5-20 pts.wt. rosin-based tackifier having >=100 deg.C softening point per 100 pts.wt. base polymer essentially comprising (meth)acrylate copolymer. A color developer in the thermosensitive recording layer which forms a thermosensitive recording body is at least one or more compd. selected from 4,4'-bis(N-p-trisulfonylurea)diphenylmethane, N-p-trylsulfonyl-N'-phenylurea, 4-hydroxy-4'-isopropoxydiphenylsulfone and bis(3-aryl-4-hydroxyphenyl)sulfone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording label, and more particularly, to a heat-sensitive recording label which has good adhesion to a polyolefin wrap, has no reduction in recording sensitivity, and has no white spots in printing.

[0002]

2. Description of the Related Art Adhesive labels are widely used for commercial, office and home use, and are widely used for labels, seals, stickers, etc.
It is processed into patches and used. A general configuration of an adhesive label is formed by laminating a surface substrate, an adhesive layer, and a release paper. Paper, film, metal foil, recording media suitable for various recording methods, etc. are used for the surface substrate,
As the release paper, a high-density base paper such as glassine paper, clay coated paper, polyethylene laminated paper or the like coated with a release agent such as a silicone compound or a fluorine compound is used. As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, emulsion-type, solvent-type, and hot-melt-type pressure-sensitive adhesives such as rubber, acrylic, and vinyl ether are used. Among them, acrylic water-dispersed pressure-sensitive adhesives are widely used in terms of safety, quality, and cost.

A heat-sensitive recording material is known which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic colorant to form a recorded image by bringing both compounds into melt contact with heat. ing. Such a thermosensitive recording medium is relatively inexpensive, has a compact recording apparatus, and is easy to maintain, so that it is used not only as a recording medium such as a facsimile or various calculators but also in a wide range of fields. For example, as one of the application fields, POS (poi
With the expansion of systemization, the use of thermosensitive recording labels has been increasing.

[0004] In supermarkets, convenience stores, and the like, a thermosensitive recording label on which information such as a price and a bar code is printed is often attached to a wrap that encloses a tray containing foods and prepared dishes. In the past, vinyl chloride was often used in this wrap, but in recent years environmental protection has increased, and there has been a demand for reduction of vinyl chloride due to problems with dioxins. So-called polyolefins such as polyethylene and polypropylene that do not generate dioxins during incineration Switching to laps is in progress. Vinyl chloride wrap is polar and relatively easy to adhere, and although it shows sufficient adhesiveness even with conventional thermal recording labels,
Polyolefin wraps are non-polar and therefore difficult to adhere.In addition, anti-fogging agents such as polyhydric alcohol fatty acid esters are kneaded into the wraps to impart anti-fogging properties and self-adhesiveness. It has become difficult.

Further, heat-sensitive recording labels generally require storage stability of a recorded image. Therefore, a method of applying an aqueous emulsion of a resin having a film forming ability and chemical resistance on a heat-sensitive recording layer, polyvinyl alcohol, etc. A method of applying a water-soluble polymer compound has been proposed. Further, an adhesive layer is provided on the back surface of the heat-sensitive recording medium, and then a release paper is provided. Normally, rubber-based, acrylic-based, and the like are used for the adhesive, and an acrylic-based water-dispersed type is particularly used. Many are used. Therefore, even during long-term storage before being used as a label, the low-molecular-weight oligomers and surfactants contained in the pressure-sensitive adhesive layer migrate to the heat-sensitive recording layer to lower the recording sensitivity. Has a problem that white spots or the like occur in printing.

For this reason, a thermal recording medium having a back coat layer mainly composed of a water-soluble polymer has been proposed, but the water-soluble polymer penetrates into the support, and a sufficient barrier property cannot be obtained. Was inferior in storage stability. In addition, there were problems such as a decrease in whiteness of the recording layer during application and drying of the back coat layer, and an increase in cost due to an increase in the number of manufacturing steps.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording label comprising a heat-sensitive recording material, a pressure-sensitive adhesive layer, and a release paper laminated in this order. The present invention relates to a heat-sensitive recording label free from deterioration of printing and white spots on printing.

[0008]

Means for Solving the Problems The present inventors have made intensive studies in view of the present situation, and as a result, have found that in a heat-sensitive recording label in which a heat-sensitive recording material, an adhesive layer and a release paper are laminated, (1) an adhesive layer Is formed of a base polymer 100 mainly composed of a (meth) acrylate copolymer.
The water-dispersed pressure-sensitive adhesive contains 5 to 20 parts by weight of a rosin-based tackifier having a softening point of 100 ° C. or more based on parts by weight. (2) The colorant in the heat-sensitive recording layer forming the heat-sensitive recording medium is 4,4'-bis (Np-trisulfonylurea) diphenylmethane, Np-tolylsulfonyl-N'-phenylurea, 4-hydroxy At least one selected from -4'-isopropoxydiphenyl sulfone and bis (3-allyl-4-hydroxyphenyl) sulfone. It has been found that the object of the present invention is achieved by simultaneously satisfying

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive recording label of the present invention comprises a heat-sensitive recording material, a pressure-sensitive adhesive layer and a release paper laminated thereon, and the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is a (meth) acrylate copolymer. For 100 parts by weight of the base polymer as the main component,
Rosin tackifier with a softening point of 100 ° C or higher
20 parts by weight of a water-dispersible pressure-sensitive adhesive, and the coloring agent contained in the heat-sensitive recording layer forming the heat-sensitive recording medium was 4,
4′-bis (Np-tolylsulfonylurea) diphenylmethane, Np-tolylsulfonyl-N′-phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) A thermosensitive recording label, characterized in that it is at least one selected from sulfones.

[0010] In the present invention, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer has a softening point of 100 ° C with respect to 100 parts by weight of a base polymer mainly composed of a (meth) acrylate copolymer.
The water-dispersed pressure-sensitive adhesive contains 5 to 20 parts by weight of the above rosin-based tackifier, but contains a rosin-based tackifier in order to improve the adhesiveness to the polyolefin wrap. Examples of the tackifier include rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, hydrogenated petroleum resin, styrene resin, and alkylphenol resin. Is the best. The rosin-based tackifier of the present invention is a rosin resin, rosin,
It includes polymerized rosin, hydrogenated rosin, rosin ester, and hydrogenated rosin ester.

The pressure-sensitive adhesive employed in the present invention contains a rosin-based tackifier having a softening point of 100 ° C. or higher, and the rosin-based tackifier comprises a base polymer (meth) acrylate ester copolymer. Oligomer is smaller in molecular weight than coalesced and is about several hundred to several thousand oligomers, so if it is contained in an adhesive, it will migrate to the thermosensitive recording layer due to low molecular weight when stored for a long time, causing a decrease in recording sensitivity. However, there is a problem that white spots or the like in printing occur.

The softening point of a rosin tackifier is 10
When the temperature is lower than 0 ° C., the composition has a low molecular weight and is almost liquid at room temperature. Therefore, migration into the heat-sensitive recording layer becomes easy, the colorant in the heat-sensitive recording layer is affected, and white spots or the like occur in printing regardless of the type of colorant. When the softening point of the rosin-based tackifier is 100 ° C. or higher, migration to the heat-sensitive recording layer is small even if it is solid at room temperature and has a low molecular weight.

In the present invention, the rosin tackifier is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the base polymer mainly composed of a (meth) acrylate copolymer. If it is less than 20 parts by weight, the adhesiveness to the polyolefin wrap will be insufficient, the adhesiveness will be lost, the migration into the heat-sensitive recording layer will be remarkable, and the recording sensitivity will be reduced and white spots will occur.

The base polymer of the pressure-sensitive adhesive employed in the present invention is obtained by polymerizing a monomer containing at least one ester group-containing monomer selected from the group of (meth) acrylates. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acryl Cyclohexyl acid, meta (acrylic acid-2)
-Ethylhexyl, isononyl (meth) acrylate,
The main component is at least one selected from lauryl (meth) acrylate and stearyl (meth) acrylate, vinyl acetate, styrene, ethylene, vinyl chloride, vinylidene chloride, ethylenically unsaturated carboxylic acid, a crosslinkable monomer, A copolymer comprising at least one copolymerizable monomer selected from (α-methyl) styrene, N-alkyl (meth) acrylamide, and (meth) acrylonitrile is preferred.

Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, monoalkylmalate having an alkyl group having 1 to 12 carbon atoms, and hydroxyethyl ( Propyl) monomalate, phthalic acid, monoalkyl (C1-12) esters of itaconic acid, and the like. Examples of the crosslinkable monomer include 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid-2.
-Hydroxypropyl, 3-hydroxyethyl (meth) acrylate, hydroxyl group-containing monomers such as mono (meth) acrylate of polyethylene glycol or polypropylene glycol, epoxy group-containing monomers such as glycidyl (meth) acrylate, (meth) acrylamide,
Monomers having a -CONH2 group or a methylol group such as diacetone acrylamide, divinylbenzene, divinylsilane, diallyl phthalate, cyclopentadiene,
Monomers having two or more ethylenically unsaturated bonds, such as methylenebisacrylamide, diallyl maleate, and tetraallyloxyethane, can be mentioned.

The polymer of the present invention is preferably a polymer having a glass transition temperature (Tg) of -73 ° C to -43 ° C.
If the Tg is lower than -73 ° C, the cohesive strength is significantly reduced, while if the Tg is higher than -43 ° C, the adhesiveness to the adherend at a low temperature tends to be reduced. (Meta) in the present invention
The base polymer mainly composed of an acrylate copolymer preferably has a molecular weight distribution of 10,000 to 10,000,000. The low molecular weight portion imparts wettability to the polyolefin wrap and improves the adhesive strength. In addition, a cohesive force is provided at a high molecular weight portion. If the low molecular weight portion is large, the wettability can be imparted, but the cohesive force is insufficient, the pressure-sensitive adhesive sticks out and adheres to the back surface of the release paper in a label form, and the workability deteriorates. Further, when the amount of the high molecular weight portion is large, the cohesive force can be provided, but the wettability to the polyolefin wrap is insufficient, and the adhesiveness is deteriorated. The gel fraction of the copolymer of the present invention with respect to toluene is preferably 30 to 70% by weight. If it is less than 30% by weight, the cohesive strength is reduced, and the pressure-sensitive adhesive sticks out. Conversely, if it exceeds 70% by weight, the adhesiveness to the wrap will decrease.

The polymer is preferably produced by a known emulsion copolymerization method (eg, a primary charge polymerization method, a monomer addition polymerization method, a pre-emulsion addition polymerization method, etc.). Examples of the emulsifier used during polymerization include potassium oleate, sodium laurate, sodium todecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, and polyoxyethylene alkyl aryl ether. Anionic surfactants such as sodium sulfate, sodium polyoxyethylene dialkyl sulfate, polyoxyethylene alkyl ether phosphate, and polyoxyethylene alkyl allyl ether phosphate; furthermore, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether , Poly (oxyethylene-oxypropylene) block copolymer, polyethylene glycol fatty acid ester, polyoxy It can be exemplified a nonionic surfactant, such as sorbitan fatty acid esters. In addition, a relatively low molecular weight polymer compound having emulsifying and dispersing ability, for example, polyvinyl alcohol, and a modified product thereof,
Polyacrylamide, polyethylene glycol derivatives,
Neutralized polycarboxylic acid copolymers, casein and the like can be used alone or in combination with the above emulsifiers. In addition, if necessary, a thickener, a wetting agent, a leveling agent, an antifoaming agent and the like may be appropriately added.

The base paper of the heat-sensitive recording material may be wood pulp such as softwood or hardwood, non-wood pulp such as kenaf, bamboo or hemp, synthetic pulp such as polyester or polyolefin, or synthetic fiber, glass fiber or ceramic fiber. And the like obtained by using inorganic fibers and the like as raw materials.

In the stock, for example, talc, kaolin, clay, calcined kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, aluminum hydroxide, calcium hydroxide,
Magnesium hydroxide, zinc hydroxide, magnesium sulfate,
Calcium silicate, white carbon, aluminosilicate,
Silica, sericite, bentonite, smectite, polystyrene resin fine particles, urea formalin resin fine particles, fine hollow fine particles and other publicly known mineral fillers and organic synthetic fillers,
In addition, various anionic, nonionic, cationic or amphoteric retention improvers, drainage improvers, paper strength improvers and internal sizing agents that have been used so far do not impair the desired effects of the present invention. And the like are appropriately selected and used as needed.

For example, polyvalent metal compounds such as Al, Fe, Sn, Zn and the like (sulfuric acid bands, aluminum chloride, sodium aluminate, basic aluminum chloride, basic aluminum such as polyaluminum hydroxide, etc.) are easily dispersed in water. Water-soluble aluminum compounds such as alumina sol, or ferrous sulfate, ferric chloride, etc.) and various sizing agents (alkyl ketene dimer, alkenyl succinic anhydride, styrene-acrylic, higher fatty acid, petroleum resin) Sizing agent and rosin-based sizing agent) and various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide / polyamine resin, polyethyleneimine, polyamine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide , Hydrophilic crosslinked polymer particles Things and their derivatives, or colloidal silica, a variety of compounds of the bentonite and the like. In addition, an internal additive for papermaking such as a dye, a fluorescent brightener, a pH adjuster, an antifoaming agent, a pitch control agent, and a slime control agent can be appropriately added as needed.

The papermaking method is not particularly limited. For example, acidic papermaking having a papermaking pH of about 4.5, or an alkaline filler such as calcium carbonate as a main component, and a papermaking pH of about 6 to about 9 to about 9 are used. It can be applied to all papermaking methods such as the so-called neutral papermaking method to make it weakly alkaline,
As the paper machine, a fourdrinier paper machine, a twin wire paper machine, a round mesh paper machine, a Yankee paper machine, or the like can be appropriately applied.

The inventors of the present invention have conducted intensive studies on colorants, and have found that the use of a specific colorant does not cause a decrease in recording sensitivity or white spots. That is, even if the softening point of the rosin-based tackifier is 100 ° C. or higher, it still migrates slightly to the heat-sensitive recording layer due to its low molecular weight. I do. Therefore, the colorant in the heat-sensitive recording layer is converted to a 4,4
4′-bis (Np-tolylsulfonylurea) diphenylmethane, Np-tolylsulfonyl-N′-phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) The object of the present invention has been achieved by using one or more selected from sulfones.

On the other hand, as the basic dye contained in the heat-sensitive recording layer in the present invention, various known dyes can be mentioned, for example, the following ones. 3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
(4-diethylamino-2-methylphenyl) -3-
A blue-coloring dye such as (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [a] fluoran, 3- (N
Green-forming dyes such as -ethyl-N-p-tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilinofluoran and 3-diethylamino-7-dibenzylaminofluoran.

3,6-bis (diethylamino) fluoran-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluoran, 3-dibutylamino-6-methyl-7-bromofluoran, 3-diethylamino-7
-Methylfluoran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluoran, rhodamine (o-chloroanilino) lactam, rhodamine (p-chloroanilino) lactam,
3-diethylamino-7,8-benzofluoran, 3-
(N-ethyl-p-toluidino) -7-methylfluoran, 3-diethylamino-6,8-dimethylfluoran, 3- (N-ethyl-N-isoamyl) amino-benzo [a] fluoran, 3,3 '-Bis (1-n-butyl-2-methylindol-3-yl) phthalide, 2-
Red coloring dyes such as (4-dodecyloxy-3-methoxystyryl) quinoline;

3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-
Methyl-N-cyclohexyl) amino-6-methyl-7
-Anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 3-di (n-pentyl) Amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (o-chlorophenylamino) fluoran, 3-di (n-butyl) amino-7- (o-chlorophenylamino) fluoran, 3-
Diethylamino-7- (o-fluorophenylamino)
Fluoran, 3-di (n-butyl) amino-7- (o-
Fluorophenylamino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p- Toluzino) Fluoran, 3- (N-
Ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-
6-chloro-7-anilinofluoran, 3- (N-methyl-Nn-propylamino) -6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7
-Anilinofluoran, 3-dibutylamino-6-methyl-7-m-toluidinofluoran, 3- (Nn-hexyl-N-ethyl) amino-6-methyl-7-anilinofluoran , 3- (N-ethyl-N-isobutyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-p-ethoxyanilinofluoran, 3-pyrrolidino-6-methyl -7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [Phthalide-3,9'-xanthen-2'-ylamino] phenyl} propane, 3-diethylamino-7-
Black coloring dyes such as (3'-trifluoromethylphenyl) aminofluorane;

3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-
2-yl] -4,5,6,7-tetrachlorophthalide,
3,3-bis [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-
2-yl] -4,5,6,7-tetrabromophthalide,
3-p- (p-dimethylaminoanilino) anilino-6
-Methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluoran, 3,6-bis (dimethylamino) fluorene-9
Dyes having an absorption wavelength in the near infrared region, such as -spiro-3 '-(6'-dimethylamino) phthalide. Of course,
It is not limited to these, and two or more of them can be used in combination as needed.

The use ratio of the basic dye and the colorant is appropriately selected according to the type of the basic dye and the colorant used, and is not particularly limited. 1 to 50 parts by weight, preferably 2 to 5 parts by weight
About 10 parts by weight of a color former is used.

The heat-sensitive recording layer paint containing these substances is as follows:
Generally, water is used as a dispersion medium, and ball mills, attritors,
It is prepared by dispersing the dye and the colorant together or separately using a stirring / pulverizer such as a sand mill.

In the coating solution, starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, are usually used as binders.
Diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, At least one of a melamine resin, an amide resin, a polyurethane resin and the like is blended in an amount of about 5 to 30% by weight based on the total solid content of the recording layer.

Various auxiliaries can be added to the coating solution, if necessary. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts. Waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, etc.
An antifoaming agent, a coloring dye and the like are appropriately added.

It is also possible to use various pigments in the coating liquid, such as kaolin, clay, calcium carbonate, calcined clay (calcined kaolin), titanium oxide, diatomaceous earth, finely divided anhydrous silica, activated clay and the like. Examples include inorganic pigments, organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, raw starch particles, and the like.

Further, depending on the purpose, a sensitizer for lowering the coloring temperature of the heat-sensitive recording layer can be used in combination. Specific examples of the sensitizer include, for example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, methylenebisstearic acid amide N-methylol stearamide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthyl benzyl ether, m-terphenyl, shu Dibenzyl oxalate, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, p-benzylbiphenyl, p-tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-
Di (3-methylphenoxy) ethane, 1,2-di (4-
Methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-
Methoxyphenoxy) -2- (3-methylphenoxy)
Ethane, p-methylthiophenylbenzyl ether,
1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenethidide, N-acetoacetyl-
Examples thereof include p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like.

In the present invention, it is possible to add a recording density preservability improver to the heat-sensitive recording layer. Examples of such a preservability improver include the following. 2,2'-
Methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert
-Butylphenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 4,4'-
Thiobis (2-methyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-
m-cresol), 1- [α-methyl-α- (4′-hydroxyphenyl) ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, 1,
1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 ′ -Thiobis (3-methylphenol), 4,4'-dihydroxy-3,3 ', 5,5'
-Tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2 -Bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-
Hindered phenol compounds such as bis (4-hydroxy-3,5-dimethylphenyl) propane,

1,4-diglycidyloxybenzene,
4,4'-diglycidyloxydiphenyl sulfone, 4
-Benzyloxy-4 '-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate,
Epoxy compounds such as cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin, N, N'-di-2-naphthyl-
Examples include p-phenylenediamine, sodium or polyvalent metal salts of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate, and bis (4-ethyleneiminocarbonylaminophenyl) methane.
The amounts of these sensitizers and storability improvers are not particularly limited, but it is generally desirable to adjust them in the range of about 4 parts by weight or less based on 1 part by weight of the color former.

It is preferable to provide a protective layer on the heat-sensitive recording layer, because the storage stability of the recording is further improved. For the protective layer formed on the heat-sensitive recording layer, a water-soluble polymer or a water-dispersible resin having a film-forming property is used. Specific examples of such water-soluble polymers or water-dispersible resins include, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, fully saponified polyvinyl alcohol,
Partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer Water-soluble polymers such as coalescing salts, ethylene / acrylic acid copolymer salts, urea resins, melamine resins, amide resins, and styrene / butadiene copolymer latex, acrylic resin latex, polyester polyurethane ionomer, and polyether polyurethane ionomer And the like.

It is also possible to add a pigment to the protective layer, for example, kaolin, clay, calcium carbonate, calcined clay (calcined kaolin), titanium oxide, diatomaceous earth, urea / formalin resin filler, etc. . The amount used is 40 to 90% by weight with respect to the protective layer.

Further, various auxiliaries can be added to the protective layer if necessary. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate and fatty acid metal salts. Lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, defoamers, coloring dyes and the like are appropriately added. In particular, by using a lubricant and a waterproofing agent together in the protective layer, the blocking resistance is further improved.

The method for forming the heat-sensitive recording layer and the protective layer is not particularly limited, and includes, for example, air knife coating, barber blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, gravure coating and the like. After the coating liquid for the heat-sensitive recording layer is applied and dried on the support by a suitable coating method, the coating liquid for the protective layer is further applied and dried on the heat-sensitive recording layer.

As the release paper, high-density base paper such as glassine paper, clay-coated paper, kraft paper or woodfree paper, or the like may be used. Styrene-butadiene copolymer, ethylene-vinyl chloride copolymer, methyl methacrylate-butadiene copolymer, ethylene-vinyl acetate copolymer, (meth) acrylate copolymer natural or synthetic resin alone or kaolin , Clay, calcium carbonate, calcined clay (calcined kaolin), base material provided with a filler layer used in combination with inorganic pigments such as titanium oxide and silica, and organic pigments such as plastic pigment, or polyethylene on kraft paper or woodfree paper etc Etc. Porirami paper laminated with a synthetic resin, solvent type or after coating a solventless silicone resin, fluorine resin or the like so that the dry weight is about 0.05 to 3 g / m ^2, a thermosetting or an electron beam or ultraviolet What formed the release agent layer by hardening etc. is used suitably. The apparatus for applying the release agent is not particularly limited, but for example, a bar coater, a direct gravure coater, an offset gravure coater, an air knife coater, a multi-stage roll coater, or the like is appropriately used.

As a method for applying the adhesive, for example, a roll
Coater, knife coater, bar coater, slotter
An coater or the like is used, and the coating amount is 5 to 50 by dry weight.
g / m ^TwoIt is adjusted within a range. Adhesive is peeling of release paper
Even if it is coated on the release agent surface, the back side of the thermal recording medium (the thermal recording layer
On the other side).

[0041]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto. In the examples, parts and% indicate "parts by weight" and "% by weight" unless otherwise specified.

Example 1 "Production of Support" NBKP (CSF 550 ml) 25
Of kaolin was added to a pulp slurry containing 75 parts of LBKP (560 ml of CSF 560 ml) so that the paper ash content was 5.0%. 2.0% band was added. The pulp slurry was paper-made by a fourdrinier cylinder dryer paper machine and processed by a 4-stage super calender to obtain a 58 g / m ² support for a thermosensitive recording medium.

"Preparation of thermosensitive recording medium" Preparation of solution A 10 parts of 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-phenylaminofluoran 5 parts of a 5% aqueous methylcellulose solution and 40 parts of water Was pulverized with a sand mill until the average particle diameter became 3 μm. Solution B Preparation A composition comprising 30 parts of 4-hydroxy-4'7-isopropoxydiphenylsulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water has a mean particle size of 3 using a sand mill.
Milled to a μm. Solution C preparation 1,2-di (3-methylphenoxy) ethane 20 parts, 5
A composition comprising 5 parts of an aqueous methylcellulose solution and 55 parts of water was pulverized by a sand mill until the average particle size became 3 μm. Solution D Preparation of 10% acetoacetyl group-modified polyvinyl alcohol aqueous solution 200 parts, kaolin (trade name: UW-90, manufactured by EMC) 100 parts, 30% zinc cetearate dispersion liquid 30 parts,
And a composition comprising 100 parts of water were mixed and stirred to obtain a coating liquid.

"Formation of Thermosensitive Recording Layer" 55 parts of A solution and 115 parts of B solution were applied on the surface of the support obtained in the above "Production of support".
Part, liquid C 80 parts, 10% polyvinyl alcohol aqueous solution 8
A coating liquid obtained by mixing and stirring 0 parts and 35 parts of calcium carbonate was coated and dried so that the coating amount after drying was 6 g / m ² , to obtain a heat-sensitive recording layer. After applying and drying the solution D on the heat-sensitive recording layer so that the coating amount after drying was 5 g / m ² , a calender treatment was performed to obtain a heat-sensitive recording material.

"Production of adhesive" 93 parts of 2-ethylhexyl acrylate, 6.5 parts of vinyl acetate, 0.5 part of acrylic acid
Parts of the monomer mixture were added to an emulsifier aqueous solution containing 1.0 part of a surfactant and 30 parts of ion-exchanged water and stirred to form a pre-emulsion. In a reaction vessel equipped with a stirrer, a thermometer, and a condenser, 1.0 part of a surfactant, 0.3 part of sodium acetate, and 30 parts of ion-exchanged water were charged with an emulsifier aqueous solution, and stirred while passing nitrogen gas. The temperature of the solution was raised to 75 ° C., and 5/100 of the pre-emulsion was added to the solution.
Initial polymerization was performed for 1 minute, and the remaining amount was added dropwise over 4 hours, and the polymerization was performed while maintaining the temperature at 75 to 80C. After the completion of the dropwise addition, the mixture was kept at 80 ° C. to carry out late-stage polymerization to obtain a copolymer emulsion. Then, this copolymer emulsion was neutralized with aqueous ammonia (concentration: 25%), and then a thickener was added to adjust the viscosity to 5000 mpas to obtain an adhesive. To 100 parts of the obtained pressure-sensitive adhesive, 10 parts of an emulsion-type rosin-based tackifier having a resin softening point of 160 ° C (trade name: Superester E-650, manufactured by Arakawa Chemical) was blended to obtain a pressure-sensitive adhesive.

The "production of thermal label" basis weight 63 g / m ² of glassine paper (Oji Paper Nakatsu Plant Ltd.) to thermosetting solvent silicone (SRX345: Toray Dow Corning) in a dry weight 1.0 g / m ^Two coatings were performed to obtain a release paper. Then, the above-mentioned pressure-sensitive adhesive was applied to the silicone-coated surface of the release paper so as to have a dry weight of 30 g / m ² to form a pressure-sensitive adhesive layer. Then, the heat-sensitive recording material was adhered on the surface of the pressure-sensitive adhesive layer to obtain a heat-sensitive recording label.

Example 2 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Thermal recording was performed in the same manner as in Example 1 except that Super Ester E-650, manufactured by Arakawa Chemical Co., Ltd.) was changed to an emulsion-type rosin-based tackifier (trade name: Harrier Star SK130D, manufactured by Harima Chemicals) having a resin softening point of 130 ° C. Got the label.

Example 3 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Emulsion type rosin-based tackifier with a resin softening point of 100 ° C (trade name: Superester E-720, manufactured by Arakawa Chemical)
Was obtained in the same manner as in Example 1 except that the label was changed to.

Example 4 In the preparation of the thermal recording medium of Example 1, 4-hydroxy-4'-isopropoxydiphenyl sulfone was replaced with 4,4'-bis (Np-trisulfonylurea) diphenylmethane Except having changed to, the thermosensitive recording label was obtained in the same manner as in Example 1.

Example 5 In the preparation of the thermosensitive recording medium of Example 1, 4-hydroxy-4'-isopropoxydiphenylsulfone was changed to Np-tolylsulfonyl-N'-phenylurea when preparing solution B. Except for the above, a thermal recording label was obtained in the same manner as in Example 1.

Example 6 In the preparation of the heat-sensitive recording material of Example 1, 4-hydroxy-4'-isopropoxydiphenyl sulfone was changed to bis (3-allyl-4-hydroxyphenyl) sulfone when preparing solution B. Except for the above, a thermal recording label was obtained in the same manner as in Example 1.

Example 7 In the preparation of the heat-sensitive recording medium of Example 1, 4-hydroxy-4'-isopropoxydiphenyl sulfone was replaced with 4,4'-bis (Np-trisulfonylurea) diphenylmethane Example 1 except that the mixture was changed to a 7/3 mixture of Np-tolylsulfonyl-N'-phenylurea.
A thermosensitive recording label was obtained in the same manner as described above.

Comparative Example 1 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Emulsion type rosin-based tackifier with a resin softening point of 75 ° C (trade name: Super Ester E-650, manufactured by Arakawa Chemical)
Was obtained in the same manner as in Example 1 except that the label was changed to.

Comparative Example 2 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Emulsion type rosin tackifier (trade name: Harrier Star DS70E, manufactured by Harima Kasei Co., Ltd.) having a resin softening point of 70 ° C.
Was obtained in the same manner as in Example 1 except that the label was changed to.

Comparative Example 3 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Superester E-650, Arakawa Chemical) 10 parts 2
A thermosensitive recording label was obtained in the same manner as in Example 1 except that the part was changed.

Comparative Example 4 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Superester E-650, Arakawa Chemical) 10 parts 3
A heat-sensitive recording label was obtained in the same manner as in Example 1 except that the amount was changed to 0 part.

Comparative Example 5 In the preparation of the thermosensitive recording medium of Example 1, 4-hydroxy-4'-isopropoxydiphenyl sulfone was changed to 2,2-bis (4-hydroxyphenyl) propane when preparing the solution B. Except for the above, a thermal recording label was obtained in the same manner as in Example 1.

Comparative Example 6 The procedure of Example 1 was repeated, except that 4-hydroxy-4'-isopropoxydiphenylsulfone was changed to 2,4'dihydroxydiphenylsulfone during the preparation of Solution B. In the same manner as in Example 1, a thermosensitive recording label was obtained.

Comparative Example 7 In the production of the pressure-sensitive adhesive of Example 1, the resin softening point was 160 ° C.
Emulsion type rosin tackifier (Product name:
Thermal recording was carried out in the same manner as in Example 1 except that Super Ester E-650 (manufactured by Arakawa Chemical Co.) was changed to an emulsion type terpene-based tackifier having a resin softening point of 125 ° C (trade name: Nanolet G-1250, manufactured by Yashara Chemical Co., Ltd.). Got the label.

The thermosensitive recording labels thus obtained were evaluated as described below, and the results are shown in Table 1. The evaluation method for each item is as follows.

"Adhesion to Polyolefin Wrap" The adhesion of the heat-sensitive recording label to the Suntech film was evaluated. ：: very strong adhesion. Δ: The label can be peeled off, but at a level that is practically acceptable. ×: The label is peeled off very easily.

"Coloring property" Using a heat-sensitive evaluation device (TH-PMD, manufactured by Okura Electric Co., Ltd.), applied energy 0.4 mJ / do.
At t, the heat-sensitive recording label was colored, and the color density of the obtained recorded image was measured in a visual mode using a Macbeth densitometer (RD-914, manufactured by Macbeth).

"White spot resistance" After the heat-sensitive recording label was treated at 60 ° C. for 3 weeks, a hot plate was pressed at 120 ° C. for 5 seconds (4 k
g / cm ² ), and the white spots of the recorded image were visually judged. The evaluation criteria for the recording image quality were as follows. ：: No white spots are observed. C: White spots are slightly observed, but at a level that does not cause any practical problem. X: The white spot is remarkable.

[0064]

[Table 1]

[0065]

As is clear from the results shown in Table 1, the heat-sensitive recording label of the present invention is a heat-sensitive recording label which has good adhesion to polyolefin wrap and does not cause a problem of lowering of recording sensitivity and white spots in printing. .

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H026 AA07 BB24 BB25 BB28 FF29 4J004 AA04 AA10 AB01 CA02 CA04 CA06 CA07 CB02 CC02 CC04 CD01 DA02 DA04 DB02 FA01

Claims (1)

[Claims] 1. A heat-sensitive recording label comprising a heat-sensitive recording material, a pressure-sensitive adhesive layer, and a release paper laminated in this order, wherein the pressure-sensitive adhesive layer and the heat-sensitive recording material simultaneously satisfy the following conditions. . (1) The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is a base polymer 10 mainly composed of a (meth) acrylate copolymer.
A water-dispersed pressure-sensitive adhesive containing 5 to 20 parts by weight of a rosin-based tackifier having a softening point of 100 ° C. or more based on 0 parts by weight. (2) The colorant in the thermosensitive recording layer forming the thermosensitive recording medium is 4,4'-bis (Np-trisulfonylurea)
Diphenylmethane, Np-tolylsulfonyl-N'-
At least one selected from phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, and bis (3-allyl-4-hydroxyphenyl) sulfone.