JP2743703B2 - Microcapsules encapsulating ultraviolet absorber and thermal recording medium using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microcapsule filler excellent in UV absorption and storage properties, and Ma
The present invention relates to a thermosensitive recording medium using microcapsules .

[0002]

2. Description of the Related Art Conventionally, in order to improve the light resistance of various substrates, a method has been proposed in which a pigment such as zinc oxide having an ultraviolet shielding effect or an organic ultraviolet absorber is finely divided and applied to the surface of the substrate. However, on the contrary, the surface of the base material is also concealed, so that it has been difficult to apply it to printed materials, display boards, and other materials that do not impair the color of the material itself.

[0003] In particular, an ultraviolet absorbent coating solution using water as a medium can be easily applied to various substrates, but a water-insoluble ultraviolet absorber is used in the form of a finely pulverized aqueous dispersion, so that ultraviolet light is used. In addition to poor absorption efficiency, for example, when applied on a printed material or the like, a problem occurs in that the printed image is hidden. Further, a water-soluble ultraviolet absorber cannot be used for applications requiring water resistance. Therefore, by encapsulating the ultraviolet absorber, the concealing property with respect to the substrate surface, the ultraviolet absorption efficiency, and the like are improved.

As a wall material for a microcapsule containing an ultraviolet absorber, a diisocyanate compound is used because preparation of the microcapsule is relatively easy. However, aromatic materials such as tolylene diisocyanate derivative and diphenylmethane diisocyanate derivative are used. When a group III isocyanate compound is used, the wall film itself tends to turn yellow upon exposure to light, which is not preferable for applications in which whiteness is regarded as important. Further, xylylene diisocyanate derivatives having properties between aromatic isocyanates and aliphatic isocyanates generally require a diluting solvent because of high viscosity,
It is not preferable from the viewpoint of environment and disaster prevention. Furthermore, the hexamethylene diisocyanate derivative of an aliphatic isocyanate whose wall film itself does not turn yellow upon exposure to light deteriorates in compatibility with an ultraviolet absorber as its viscosity increases, and therefore, the wall film strength of the microcapsules becomes insufficient. It cannot be obtained, and problems such as precipitation of the ultraviolet absorber encapsulated in the microcapsules occur.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a microcapsule filler which is excellent in ultraviolet absorbing properties and which does not adversely affect an ultraviolet absorbent coated material, by solving the above-mentioned problems. Further, the present invention provides an ultraviolet absorber
No adverse effects due to the encapsulated microcapsules
To provide a thermosensitive recording medium with improved lightfastness.
You.

[0006]

According to the present invention, a microcapsule containing an ultraviolet absorbent has a viscosity of 1 at 25 ° C. as measured by a B-type viscometer as a microcapsule wall film material.
By providing a microcapsule encapsulating an ultraviolet absorber using a hexamethylene diisocyanate derivative of 000 cps or less, a microcapsule excellent in ultraviolet absorption and having no adverse effect on the ultraviolet absorber coated material was found and the present invention was completed. Reached. Also, such micro
Capsule in recording layer of thermal recording medium and / or protective layer
To obtain the desired heat-sensitive recording material.
That is, the present invention has been completed.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention, as a wall film material of microcapsules containing an ultraviolet absorbent state, and are not viscosity at 25 ° C. when measured by a B-type viscometer using the following hexamethylene diisocyanate derivatives 1000 cps, the Kabemakuzai Eye to decrease viscosity
No substantial dilution solvent is required. Incidentally, when obtained by adding an organic solvent to reduce the viscosity of hexamethylene diisocyanate derivatives, new problems such as the concentration of the UV absorber in odor and microcapsules decreases occurs. Furthermore , the viscosity of the hexamethylene diisocyanate derivative is increased to 1000 cps as the polymer becomes higher.
If the ratio exceeds the above range, the compatibility with the ultraviolet absorber deteriorates, so that sufficient wall strength of the microcapsules cannot be obtained, and the ultraviolet absorber encapsulated in the microcapsules precipitates. this
Therefore, in the present invention, the viscosity at 25 ° C. is 1 as described above.
Induction of hexamethylene diisocyanate of 000 cps or less
The conductor is used, and in particular, in order to make the average particle diameter of the microcapsules 3 μm or less, the viscosity of the hexamethylene diisocyanate derivative is preferably 800 cps or less. In addition, the viscosity defined in the present invention
Degree of concentration in the state without the diluent solvent (organic solvent)
Refers to the viscosity of xamethylene diisocyanate derivative
It is.

The viscosity at 25 ° C. used in the present invention is 100.
Examples of the hexamethylene diisocyanate derivative having 0 cps or less include isocyanurate type hexamethylene diisocyanate (trimer of hexamethylene diisocyanate), a mixture of hexamethylene diisocyanate trimer and pentamer or more, and buret type hexamethylene diisocyanate. However, isocyanurate-type hexamethylene diisocyanate is particularly preferred because of its excellent compatibility with the ultraviolet absorber. Further, adducts of these specific hexamethylene diisocyanate derivatives and polyols can also be used.

As long as the effects of the present invention are not impaired, the following polyvalent isocyanate compounds and polyol compounds can be used in combination. For example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6
-Tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate,
Diphenylmethane-4,4'-diisocyanate, 3,
3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate,
4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate,
Diisocyanates such as cyclohexylene-1,2-diisocyanate and cyclohexylene-1,4-diisocyanate; triisocyanates such as 4,4 ', 4 "-triphenylmethane triisocyanate and toluene-2,4,6-triisocyanate , Tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, propylene-1,
Diisocyanates such as 2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate, toluene- Triisocyanates such as 2,4,6-triisocyanate, 4,4'-
Tetraisocyanates such as dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate; adducts of hexamethylene diisocyanate with trimethylolpropane; adducts of 2,4-tolylenediisocyanate with trimethylolpropane; Isocyanate prepolymers such as adducts of diisocyanate and trimethylolpropane, and adducts of triresin isocyanate and hexanetriol are exemplified.

As the polyol compound, for example, ethylene glycol, 1,3-propanediol, 1,4
-Butanediol, 1,5-pentanediol, 1,6
-Hexanediol, 1,7-heptanediol, 1,
8-octanediol, propylene glycol, 2,3
-Dihydroxybutane, 1,2-dihydroxybutane,
1,3-dihydroxybutane, 2,2-dimethyl-1,
3-propanonediol, 2,4-pentanediol,
2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol,
Dihydroxycyclohexane, diethylene glycol,
1,2,6-trihydroxyhexane, phenylethylene glycol, 1,1,1-trimethylolpropane,
A mixture of an aliphatic polyol such as hexanetriol, pentaerythritol and glycerin, an aromatic polyhydric alcohol such as 1,4-di (2-hydroxyethoxy) benzene and 1,3-di (2-hydroxyethoxy) benzene, and an alkylene oxide; Condensation product, p-xylylene glycol, m-xylylene glycol, α, α'-dihydroxy-p-diisopropylbenzene, 4,4'-dihydroxydiphenylmethane, 2- (p, p'-dihydroxydiphenylmethyl) benzyl alcohol 4,4'-isopropylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, ethylene oxide adduct of 4,4'-isopropylidene diphenol, 4,4'-isopropyl Of redenediphenol And propylene oxide adducts. Needless to say, the polyvalent isocyanate compound and the polyol compound used together as required are not limited to the above compounds, and two or more kinds can be used in combination as needed.

The amount of the capsule wall material used is not particularly limited. For example, the ratio of the wall film material is 20 to 70% by weight based on the total amount of the ultraviolet absorbent and the microcapsule wall film material . It is desirable to select the amount so as to be preferably in the range of 25 to 50% by weight.

In the present invention, specific examples of the ultraviolet absorber contained in the microcapsules include the following. Phenyl salicylate, p-tert-butylphenyl salicylate, salicylic acid ultraviolet absorbers such as p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5
Benzophenone-based ultraviolet absorbers such as sulfobenzophenone, 2- (2'-hydroxy-5'-methylphenyl)
Benzotriazole, 2- (2'-hydroxy-5'-
tert-butylphenyl) benzotriazole, 2-
(2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5
Chlorobenzotriazole, 2- (2'-hydroxy-
3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3',
5'-di-tert-amylphenyl) benzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4",
5 ", 6" -tetrahydrophthalimide-methyl)-
5'-methylphenyl] -benzotriazole, 2-
(2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-undecyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy- 3'-tridecyl-5'-methylphenyl) benzotriazole, 2-
(2'-hydroxy-3'-tetradecyl-5'-methylphenyl) benzotriazole, 2- [2'-hydroxy-4 '-(2 "-ethylhexyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy −
4 '-(2 "-ethylheptyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4'-
(2 "-ethyloctyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4 '-(2" -propyloctyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4'-(2 "-Propylheptyl) oxyphenyl] benzotriazole, 2-
[2'-hydroxy-4 '-(2 "-propylhexyl) oxyphenyl] benzotriazole, 2- [2'
-Hydroxy-4 '-(1 "-ethylhexyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4'-(1" -ethylheptyl) oxyphenyl]
Benzotriazole, 2- [2'-hydroxy-4'-
(1 "-ethyloctyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4 '-(1" -propyloctyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4'-(1 "-Propylheptyl) oxyphenyl] benzotriazole, 2-
[2'-hydroxy-4 '-(1 "-propylhexyl) oxyphenyl] benzotriazole, 5-tert-
Octyl butyl-3- (5-chloro-2H-benzotriazol-2-yl) -4-hydroxybenzene-propionate, methyl-3- [3-tert-butyl-5- (2
H- condensate of benzotriazole-2-b) -4- hydroxyphenyl] propionate and polyethylene glycol (molecular weight: about 300). Of course, the invention is not limited to these, and two or more of them can be used in combination as needed. Among these ultraviolet absorbers, benzotriazole-based ultraviolet absorbers which are liquid at ordinary temperature are preferably used because they have high absorption efficiency for ultraviolet light and can be easily encapsulated at a high concentration because they are liquids. Specific examples include 2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole,
2- [2'-hydroxy-4 '-(2 "-ethylhexyl) oxyphenyl] benzotriazole, 5-tert-
Octyl butyl-3- (5-chloro-2H-benzotriazol-2-yl) -4-hydroxybenzene-propionate, methyl-3- [3-tert-butyl-5- (2
H- condensate of benzotriazole-2-b) -4- hydroxyphenyl] propionate and polyethylene glycol (molecular weight of about 300) can be mentioned. Of course, the present invention is not limited to these, and two or more of them can be used in combination. Note that the amount of the ultraviolet absorber is preferably to 0.1 to 3.0 g / m ² is present on the substrate, more preferably in the range of 0,2~2.0g / m ^2. When the amount of the ultraviolet absorbent is less than 0.1 g / m ² on the substrate, the ultraviolet absorbing effect is low. 3.0 g / m ²
If it exceeds, information and images of the base material are hidden. It is preferable that the microcapsules contain an ultraviolet absorber in an amount of 30 to 80% by weight based on the total of the ultraviolet absorber and the microcapsule wall material. When the amount of the ultraviolet absorber is less than 30% by weight, the amount of the microcapsules to be applied must be increased in order to prevent the deterioration of the base material due to light exposure. I will.

The microcapsules containing the ultraviolet absorbent according to the present invention are prepared by emulsifying and dispersing a solution (oil-based liquid) containing the above-mentioned specific hexamethylene dissocyanate derivative and the ultraviolet absorbent as main components in an aqueous medium. It is prepared by a method of forming a polymer material wall film around.

The microcapsules used in the present invention may contain a high-boiling solvent, if necessary, as long as the effects of the present invention are not impaired. The high-boiling solvent is not particularly limited, and can be appropriately selected from various high-boiling hydrophobic media used in the field of pressure-sensitive copying paper, and specifically, for example, tricresyl phosphate, Phosphates such as octyl diphenyl phosphate, phthalates such as dibutyl phthalate and dioctyl phthalate, carboxylic esters such as butyl oleate, various fatty acid amides, diethylene glycol dibenzoate, monoisopropyl naphthalene, diisopropyl naphthalene Alkylated naphthalenes such as
Alkylated benzenes such as 1-methyl-1-phenyl-1-tolylmethane, 1-methyl-1-phenyl-1-xylylmethane, 1-phenyl-1-tolylmethane, alkylated biphenyls such as isopropylbiphenyl, o-
Examples include xenoxyalkanes such as phenylphenol glycidyl ether, acrylic esters such as trimethylolpropane triacrylate, esters of polyhydric alcohol and unsaturated carboxylic acid, chlorinated paraffin, and kerosene. Needless to say, two or more of these can be used in combination.

In the present invention, various anions, nonions, cations, amphoteric surfactants and water-soluble polymers are used as the emulsifier, and acetoacetyl group-modified polyvinyl alcohol which provides a water-resistant effect by low-temperature curing. (including an acetoacetyl group-modified, partially saponified polyvinyl alcohol), carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol is preferable, especially (including an acetoacetyl group-modified, partially saponified polyvinyl alcohol) acetoacetyl group-modified polyvinyl alcohol aldehydes <br / > It is more preferably used because an excellent water resistance effect is obtained by the reaction with the compound. The amount of the surfactant or the water-soluble polymer as an emulsifier is not particularly limited, but is preferably 1 to 50% by weight, more preferably 3 to 50% by weight, based on the microcapsule core material and the wall film material. ~
It is desirable to adjust so as to be in the range of about 30% by weight.

In addition, an oil-soluble fluorescent dye, a colored dye, a release agent and the like can be added to the capsule.

The average particle size of the capsule used in the present invention is 0.1 to 3 in consideration of the ultraviolet absorption efficiency and the coating property of the coating solution.
It is desirable to adjust it in the range of about μm, and the obtained capsule dispersion is generally contained in a layer by a method of adding it to an aqueous or solvent-based paint. The content of the capsule in the paint is 5 to 80% by weight of the total solids, more preferably 2 to 80% by weight.
It is desirable to adjust within the range of about 0 to 70% by weight.

Examples of the water-soluble or water-dispersible polymer used in the water-based coating liquid containing microcapsules containing an ultraviolet absorber used in the present invention include starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, and the like. Gelatin, casein, gum arabic, 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, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene
Examples thereof include a butadiene copolymer emulsion, a urea resin, a melamine resin, an amide resin, and a polyurethane ionomer. Among them, acetoacetyl group-modified polyvinyl alcohol and carboxy-modified polyvinyl alcohol are particularly preferably used for forming a strong film.

It is also possible to use various pigments in combination, for example, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined Examples include inorganic pigments such as kaolin and colloidal silica, and organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch particles. It is generally desirable to adjust the amount of use in the range of about 5 to 500 parts by weight with respect to 100 parts by weight of the resin component.

Further, if necessary, a lubricant such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax or the like, or a surfactant such as sodium dioctyl sulfosuccinate (dispersant, wetting agent) may be contained in the coating liquid. ), An antifoaming agent, and various auxiliaries such as water-soluble polyvalent salts such as potassium alum and aluminum acetate. In order to further improve the water resistance, a curing agent such as glyoxal, boric acid, dialdehyde starch, or an epoxy compound can be added.

The coating liquid containing microcapsules containing an ultraviolet absorber is generally prepared using water as a dispersion medium, but when used in a solvent system, the coating liquid is prepared by various known methods such as a filtration method and a spray drying method. The capsule is dried and added to the solvent-based paint. The coating solution thus prepared is applied to a substrate by a suitable coating device, but the amount of coating is not particularly limited, but is generally 0.1 to 20 g / g.
m ² , preferably in the range of about 0.5 to 10 g / m ² .

The substrate on which the coating liquid obtained in the present invention is applied includes, for example, metals, plastic films,
Paper, cloth, non-woven fabric, vinyl, wood, lacquerware, porcelain, glass, etc.The application method is water-based paint, spray method, dipping method, and base material that can be applied continuously.
For example, it can be applied by an appropriate coating method such as an air knife coater, a blade coater, a bar coater, a roll coater, a gravure coater, and a curtain coater. In the case of a solvent-based coating, the above various methods can be applied, and the coating can be performed by various printing methods. You can also. In addition, depending on the substrate, microcapsules containing the ultraviolet absorbent of the present invention can be mixed with the substrate and used.

When the microcapsule of the present invention is applied to a heat-sensitive recording medium, the microcapsule containing an ultraviolet absorbent can be contained in the heat-sensitive recording layer. It is preferable to contain it in terms of the ultraviolet absorbing effect.

As the basic dye constituting the heat-sensitive recording layer, various known colorless or light-colored basic dyes can be used. Specifically, for example, 3,3-bis (p-dimethylaminophenyl) -6 -Dimethylaminophthalide, 3
-(4-diethylamino-2-methylphenyl) -3-
(4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [a] fluoran, 3- (N-ethyl-Np
-Tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilinofluoran, 3
-Diethylamino-7-dibenzylaminofluoran,
3,6-bis (diethylamino) fluoran-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluoran , 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-toluidino) fluoran, 3- (N-ethyl-N-fluor Furylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-
Anilinofluoran, 3- (N-methyl-NNn-propylamino) -6-methyl-7-anilinofluoran,
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, 2,2-bis {4- [6 '-(N
-Cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] phenyl} propane, 3,6,11-tri (dimethylamino) fluoran and the like. Of course, the present invention is not limited to these, and two or more of them can be used as needed.

Various materials are also known as colorants used in combination with the above basic dyes, for example, inorganic clays such as activated clay, attapulgite, colloidal silica and aluminum silicate; Isopropylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4 '
-Dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3-allyl-
4-hydroxyphenyl) sulfone, 4-hydroxy-
4'-methyldiphenylsulfone, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, butyl bis (p-hydroxyphenyl) acetate, bis (p- (Hydroxyphenyl) methyl acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3- Bis [α-methyl-α-
Phenolic compounds such as (4'-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfine, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- {3- ( p-
Tolylsulfonyl) propyloxy] salicylic acid, 5-
[P- (2-p-methoxyphenoxyethoxy) cumyl] aromatic carboxylic acids such as salicylic acid, and zinc, magnesium, aluminum of these aromatic carboxylic acids;
Examples thereof include salts with polyvalent metals such as calcium, titanium, manganese, tin, and nickel, and organic acid substances such as an antipyrine complex of zinc thiocyanate.

The ratio between 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. A coating material for a heat-sensitive recording layer containing these substances is generally prepared by dispersing a dye and a colorant together or separately with a stirring / pulverizing machine such as a ball mill, an attritor, and a sand mill using water as a dispersion medium. You.

In the heat-sensitive recording layer 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, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid At least one of a copolymer salt, a styrene / acrylic acid copolymer salt, a styrene / butadiene copolymer emulsion, a urea resin, a melamine resin, an amide resin, and a polyurethane resin is 5 to 5% of the total solid content of the recording layer. 30% by weight
It is blended in the range of the degree.

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 fluorescent dye, a coloring dye and the like are appropriately added. Moreover, Mai when blended microcapsules encapsulating this onset Ming ultraviolet absorber in the recording layer coating liquid, increasing the light resistance
About the addition amount of the black capsule, the ultraviolet absorber
What is necessary is just to add according to the usage amount (application amount on a base material) .

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

Further, a sensitizer can be used in combination depending on the purpose. Specific examples of the sensitizer include, for example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, methylenebisstearic acid amide N-methylolstearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalic acid-di- p-methylbenzyl, oxalic acid-di-p-
Chlorobenzyl, p-benzylbiphenyl, 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-acetotoluizide, p-acetophenethidide,
Examples thereof include N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like. The use amount of these sensitizers is not particularly limited, but it is generally desirable to adjust the sensitizer within a range of about 4 parts by weight or less based on 1 part by weight of the color former.

In order to enhance the preservability of the recorded image, a preservability improver may be added according to the purpose. Specific examples of such a preservability improver include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and 2,2'-ethylenebis (4-methyl-6-tert
-Butylphenol), 2,2'-methylenebis (4,
6-di-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol),
2,2'-ethylidenebis (4-methyl-6-tert-butylphenol), 2,2'-ethylidenebis (4-ethyl-6-tert-butylphenol), 2,2'-
(2,2-propylidene) bis (4,6-di-tert-butylphenol), 2,2'-methylenebis (4-methoxy-6-tert-butylphenol), 2,2'-methylenebis (6-tert-butylphenol) ), 4,4'-
Thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (5-methyl-
6-tert-butylphenol), 4,4'-thiobis (2-chloro-6-tert-butylphenol), 4,
4'-thiobis (2-methoxy-6-tert-butylphenol), 4,4'-thiobis (2-ethyl-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-bis (4-hydroxy-3,5
Hindered phenol compounds such as -dimethylphenyl) propane, 1,4-diglycidyloxybenzene,
Epoxy compounds such as 4'-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin, N, N '
-Di-2-naphthyl-p-phenylenediamine, 2,
Sodium 2'-methylenebis (4,6-di-tert-butylphenyl) phosphate and the like.

[0032] The microcapsules of the present invention when applied to heat-sensitive recording material, said as, who provided a protective layer containing microcapsules encapsulating an ultraviolet absorber, but is more effective, such a protective The layer is mainly composed of microcapsules and a binder made of a water-soluble or water-dispersible polymer compound. Specific examples of such binders include, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, 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, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, melamine resin, Amide resins, polyurethane resins and the like can be exemplified. Among them, acetoacetyl group-modified polyvinyl alcohol and carboxy-modified polyvinyl alcohol can form a strong film. Preferably used for. In addition, UV absorber
Microcapsule when compounding microcapsules in the protective layer
Regarding the amount of cell used, the amount of the ultraviolet absorber used
(The amount of application on the substrate) .

In the protective layer, a pigment can be added as needed in order to further improve printability and sticking. Specific examples thereof include calcium carbonate,
Inorganic pigments such as zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined kaolin, colloidal silica, styrene microballs, nylon powder, polyethylene powder, urea. Organic pigments such as formalin resin fillers and raw starch particles are exemplified. Generally, it is desirable to adjust the amount of use in the range of about 5 to 300 parts by weight with respect to 100 parts by weight of the binder component.

The method for preparing the coating liquid for forming the protective layer is not particularly limited. Generally, water is used as a dispersion medium, and the above-mentioned specific microcapsules (dispersion liquid), a binder, and a pigment to be added as necessary are used. It is prepared by mixing. Further, in the coating liquid for the protective layer, if necessary, zinc stearate, calcium stearate, polyethylene wax,
Lubricants such as carnauba wax, paraffin wax and ester wax; surfactants (dispersants and wetting agents) such as dioctyl sodium sulfosuccinate; antifoaming agents; and various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate. Can also be added as appropriate. In order to further improve the water resistance, a curing agent such as glyoxal, boric acid, dialdehyde starch, or an epoxy compound can be used in combination.

The method for forming the heat-sensitive recording layer and the protective layer is not particularly limited. For example, an appropriate method such as air knife coating, variver blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. After the coating liquid for the recording layer is applied and dried on the support by a coating method, the coating liquid for the protective layer is further applied and dried on the recording layer. The support is appropriately selected from paper, plastic film, synthetic paper, nonwoven fabric, metal deposit, and the like.
The coating amount of the recording layer coating liquid is 2 to 12 g / dry weight.
m ^2, is preferably adjusted 3 to 10 g / m ² approximately, the coating amount of the protective layer coating composition is 0.1 to 20 g / m ² by dry weight, preferably 0.5 to 10 g / m ² range of about You.

If necessary, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Furthermore, an undercoat layer is provided on the support, or a smoothing treatment such as super calendaring is performed after each layer is coated,
Alternatively, various known techniques in the field of heat-sensitive recording material production can be added as necessary, such as applying a pressure-sensitive adhesive treatment to the back surface of the recording material to process it into an adhesive label.

[0037]

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 to such specific Examples. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Example 1 Preparation of Solution A 12% of acetoacetyl group-modified partially saponified polyvinyl alcohol (trade name: Gosefimer Z-210, manufactured by Nippon Synthetic Chemical Co., Ltd.) was placed in a stirring and mixing vessel equipped with a heating device. 220 parts of an aqueous solution was added to obtain an aqueous medium for producing capsules. Separately, 2- (2'-hydroxy-3'-dodecyl-5'-
Methylphenyl) benzotriazole [trade name: Tinuvin 171, Ciba-Geigy Ltd.] 77 parts by 600cps viscosity at 25 ° C., the main component isocyanate wetting over preparative hexamethylene diisocyanate [trade name: Takenate D
-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.] 33 parts of the solution obtained by heating, mixing and stirring to 40 ° C. were mixed with the TK homomixer (model HV-M, manufactured by Tokushu Kika Kogyo Co., Ltd.) in the aqueous medium for capsule production. The emulsion was emulsified and dispersed while cooling so that the average particle diameter became 2 μm. Then, 175 parts of water was added to the emulsified dispersion, and the mixture was reacted at 90 ° C. for 5 hours with stirring to prepare a microcapsule dispersion having a wall film made of a polyurethane / polyurea resin containing an ultraviolet absorbent.

[Example 2] Preparation of solution B In preparation of solution A, the viscosity at 25 ° C was 600 cps.
Isocyanurate type hexamethylene diisocyanate (Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity of 800 at 25 ° C. instead of 33 parts.
cps, the main component of which is isocyanurate-type hexamethylene diisocyanate [trade name: Takenate D-175H]
N, manufactured by Takeda Pharmaceutical Company Limited] was used in the same manner as in Example 1 except that 33 parts were used.

[Example 3] Preparation of liquid C In preparation of liquid A, the viscosity at 25 ° C was 600 cps.
Isocyanurate-type hexamethylene diisocyanate (trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity of 260 at 25 ° C. instead of 33 parts.
In cps, the main component is isocyanurate type hexamethylene diisocyanate [trade name: Takenate D-177N,
Liquid C was prepared in the same manner as in Example 1 except that 33 parts of Takeda Pharmaceutical Company was used.

Example 4 Preparation of Solution D In the preparation of Solution A, the viscosity at 25 ° C. was 600 cps.
Isocyanurate-type hexamethylene diisocyanate (trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity of 240 at 25 ° C instead of 33 parts.
cps, whose main component is an isocyanurate-type hexamethylene diisocyanate compound [trade name: Desmodur TP
LS2550, manufactured by Sumitomo Bayer Urethane Co.] was used in the same manner as in Example 1 except that 33 parts were used.

Example 5 Preparation of Solution E In the preparation of Solution A, 2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole 7
2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole 55 instead of 7 parts
Parts, except that 22 parts of diisopropylnaphthalene were used.
Solution E was prepared in the same manner as in Example 1.

Comparative Example 1 Preparation of Solution F In the preparation of Solution A, the viscosity at 25 ° C. was 600 cps.
Isocyanurate type hexamethylene diisocyanate (trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity at 25 ° C of 2500 in place of 33 parts.
A mixture of cps isocyanurate-type hexamethylene diisocyanate and a polymer or polymer of hexamethylene diisocyanate [trade name: Takenate D-170]
N, manufactured by Takeda Pharmaceutical Company Limited] was used in the same manner as in Example 1 except that 33 parts were used.

Comparative Example 2 Preparation of Solution G In the preparation of Solution A, the viscosity at 25 ° C. was 600 cps.
Isocyanurate-type hexamethylene diisocyanate compound (trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity at 25 ° C. of 2
A mixture of 500 cps isocyanurate type hexamethylene diisocyanate and a polymer or polymer of hexamethylene diisocyanate [trade name: Takenate D-1]
70N, using manufactured by Takeda Chemical Industries, Ltd.] 33 parts, further 2
Instead of 77 parts of-(2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole , 2-
Solution G was prepared in the same manner as in Example 1, except that 55 parts of (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole and 22 parts of diisopropylnaphthalene were used.

[Comparative Example 3] Preparation of solution H In preparation of solution A, the viscosity at 25 ° C was 600 cps.
Isocyanurate-type hexamethylene diisocyanate compound (trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity at 25 ° C. of 2
A mixture of a 500 mps buret type hexamethylene diisocyanate and a polymer or polymer of hexamethylene diisocyanate (trade name: Sumidur N-32)
00, by using the Sumitomo Bayer Urethane Co., Ltd.], 33 parts, is
Furthermore , 2- (2'-hydroxy-3'-dodecyl-5'-
Instead of 77 parts of methylphenyl) benzotriazole , 2- (2'-hydroxy-3'-dodecyl-5'-
A liquid H was prepared in the same manner as in Example 1, except that 55 parts of methylphenyl) benzotriazole and 22 parts of tricresyl phosphate were used.

[Comparative Example 4] Preparation of liquid I In preparation of liquid A, the viscosity at 25 ° C was 600 cps.
Isocyanurate-type hexamethylene diisocyanate compound (trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.) having a viscosity of 1 at 25 ° C instead of 33 parts.
A mixture of 500 cps isocyanurate type hexamethylene diisocyanate and a polymer or polymer of hexamethylene diisocyanate [trade name: SBU-isocyanate 0861A, manufactured by Sumitomo Bayer Urethane Co.] 33
A capsule I was prepared in the same manner as in Example 1 except that the above parts were used.

220 parts of each of the above nine kinds of preparation solutions,
150 parts of a 10% aqueous solution of acetoacetyl group-modified fully saponified polyvinyl alcohol [trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Co., Ltd.], 40 parts of glyoxal
% Aqueous solution was mixed and stirred, and the coating liquid obtained was coated and dried on coated paper on which yellow ink had been offset-printed in advance so that the weight after drying was 3 g / m ^2, and the test paper was dried. I got

The following evaluation was carried out on 10 types of test papers including the 9 types of test papers thus obtained and the printing paper not coated with the coating liquid (Comparative Example 5), and the results are shown in [Table 1]. . [Light resistance] The initial optical density of the printed portion of each test paper and the optical density after exposure to direct sunlight for 20 days were determined by Macbeth RD-914.
(Blue filter) to evaluate the light fastness of each coating solution.

[Heat resistance] Each test paper was heated at 70 ° C for 2 hours.
After leaving for 4 hours, the bleeding of the ink in the printed portion was visually determined.

[0050]

[Table 1]

Next, a mask containing the ultraviolet absorbent of the present invention is included.
An example in which the microcapsule is applied to a thermosensitive recording medium will be described. Example 6 Preparation of Solution J 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 5% aqueous solution of methylcellulose 5
Parts and 40 parts of water were pulverized by a sand mill until the average particle diameter became 3 μm. Liquid K preparation A composition consisting of 30 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 5 parts of a 5% aqueous solution of methylcellulose and 80 parts of water was sand-milled to have an average particle size of 3 parts.
Milled to a μm. Preparation of Liquid L A composition comprising 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose and 55 parts of water was pulverized with a sand mill until the average particle diameter became 3 μm. Formation of recording layer 55 parts of J solution, 115 parts of K solution, 80 parts of L solution, 80 parts of a 10% aqueous solution of polyvinyl alcohol, and 3 parts of calcium carbonate
The coating solution obtained by mixing and stirring 5 parts was coated and dried on one side of a high-quality paper of 60 g / m ² so that the coating amount after drying was 6 g / m ² to form a heat-sensitive recording layer. Formation of protective layer 220 parts of solution A, 150 parts of a 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol, kaolin [trade name: UW
-90, manufactured by EMC] 15 parts, zinc stearate 30
% Of a dispersion comprising 6 parts of a dispersion and 30 parts of water were mixed and stirred, and the coating liquid for a protective layer was applied and dried on the recording layer so that the coating amount after drying was 6 g / m ^2. Then, a super calender treatment was performed to obtain a thermosensitive recording medium.

[Example 7] In Example 6, solution A 220 was used.
A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of the liquid B was used instead of the parts. Example 8 A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of Liquid A was used instead of 220 parts of Liquid A. Example 9 A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of Liquid A was used instead of 220 parts of Liquid A. Example 10 A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of Liquid A was used instead of 220 parts of Liquid A.

Example 11 Preparation of Liquid M and Preparation of Thermosensitive Recording Material 100 parts of calcined clay (trade name: Ansilex, manufactured by EMC, oil absorption 110 ml / 100 g), 100 parts of a 10% aqueous solution of polyvinyl alcohol and 200 parts of water Were mixed and stirred to obtain a coating liquid for an undercoat layer. 60g
/ M ² of high-quality paper on one side of the coating solution after drying the solution M is 7 g /
m ^2, and then the coating for the recording layer and the coating for the protective layer used in Example 6 were dried and supercalendered so that the coating amounts after drying would be 6 g / m ² respectively. A thermosensitive recording medium was obtained.

Example 12 In the preparation of Liquid K, 30 parts of bis (4-hydroxyphenylthioethoxy) methane was used in place of 30 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, and in the preparation of Liquid L, A heat-sensitive recording material was obtained in the same manner as in Example 6, except that 20 parts of bis (4-hydroxyphenylthioethoxy) methane was used instead of 20 parts of -di (3-methylphenoxy) ethane.

[Example 13] In the preparation of L solution, 2- part was replaced with 20 parts of 1,2-di (3-methylphenoxy) ethane.
A heat-sensitive recording material was obtained in the same manner as in Example 6, except that 20 parts of naphthylbenzyl ether was used. [Example 14] A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 20 parts of p-benzylbiphenyl was used instead of 20 parts of 1,2-di (3-methylphenoxy) ethane in the preparation of Liquid L. Was.

Example 15 In the preparation of solution K, instead of 30 parts of 4-hydroxy-4'-isopropylidenediphenylsulfone, 4,4'-isopropylidenediphenol 3 was used.
A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 0 part was used. [Example 16] In the preparation of solution K, 4-hydroxy-4'-
A thermosensitive recording material was obtained in the same manner as in Example 6, except that 30 parts of 1,1'-bis (4-hydroxyphenyl) cyclohexane was used instead of 30 parts of isopropoxydiphenyl sulfone.

Example 17 In the preparation of solution K, di (4-hydroxy-3-methylphenyl) was used instead of 30 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone.
A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 30 parts of sulfide was used. Example 18 In the preparation of a coating liquid for a protective layer, 10 parts of a 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol was replaced with 10 parts of carboxy-modified polyvinyl alcohol.
A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 150 parts of a 15% aqueous solution and 15 parts of calcium carbonate were used instead of 15 parts of kaolin.

[Comparative Example 6]
A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of the liquid F was used instead of the parts. Comparative Example 7 A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of Liquid A was used instead of 220 parts of Liquid A.

[Comparative Example 8]
A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of the H liquid was used instead of the parts. Comparative Example 9 A thermosensitive recording medium was obtained in the same manner as in Example 6, except that 220 parts of Liquid A was used instead of 220 parts of Liquid A.

The following evaluation tests were carried out on the 17 types of heat-sensitive recording media thus obtained, and the results are shown in Table 2. [Evaluation] [Coloring property] Applied energy 0.4 mJ / dot using a thermo-sensitive evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.)
Each of the thermosensitive recording media is colored by using a Macbeth densitometer [RD-914, manufactured by Macbeth Co.] with a color density of the obtained recorded image.
Was measured in visual mode. [Light resistance] The initial density of the background portion of the heat-sensitive recording medium after recording and the density of the background portion after exposure to direct sunlight for 10 days were measured with a Macbeth densitometer (using a blue filter). [Plasticizer resistance] Polycarbonate pipe (40mm
A wrap film (trade name: KMA-W, manufactured by Mitsui Toatsu Chemicals, Inc.) is wound three times on a (φ tube), the thermosensitive recording medium recorded by the above method is placed thereon, and the wrap film is further placed thereon. Was wound three times and left at 40 ° C. for 24 hours, and the color density was measured with a Macbeth densitometer (visual mode) to evaluate the plasticizer resistance. (High-temperature and high-humidity resistance)
The color development density and the background density after standing at 50 ° C. and 75% RH for 24 hours were measured with a Macbeth densitometer (visual mode) to evaluate the high temperature and high humidity resistance. [Solvent resistance] The surface of the recording paper was wiped with a gauze impregnated with ethanol, and the fog density was measured with a Macbeth densitometer (visual mode) to evaluate the solvent resistance.

[0061]

[Table 2]

[0062]

As is clear from the results of Tables 1 and 2, the ultraviolet absorbing microcapsules of the present invention can efficiently absorb ultraviolet rays, suppress the deterioration of the base material with respect to light, and furthermore, be sensitive to heat. When applied to a recording medium, it was a heat-sensitive recording medium with extremely little discoloration in the background and excellent color development and preservability.

Continuation of the front page (56) References JP-A-5-184909 (JP, A) JP-A-4-249256 (JP, A) JP-A-3-54276 (JP, A) JP-A-58-153947 (JP) , A)

Claims (6)

(57) [Claims] 1. A microcapsule containing an ultraviolet absorbent, wherein a hexamethylene diisocyanate derivative having a viscosity at 25 ° C. of 1000 cps or less measured by a B-type viscometer is used as a microcapsule wall film material. Agent-encapsulated microcapsules. 2. The ultraviolet absorbent-encapsulated microcapsules according to claim 1, wherein the hexamethylene diisocyanate derivative is an isocyanurate-type hexamethylene diisocyanate. 3. The method according to claim 1, wherein the ultraviolet absorbent is liquid at room temperature.
Or the microcapsule containing the ultraviolet absorbent according to claim 2. 4. The microcapsules having an average particle size of 0.1
The microcapsule according to claim 1, 2 or 3 , wherein the diameter of the microcapsule is up to 3 µm . 5. The ultraviolet absorber in microcapsules, claim containing 30 to 80% by weight relative to the total of the ultraviolet absorber and the microcapsule wall film material 1, 2, 3 or 4
The microcapsule as described. 6. The microcaps according to claim 1, wherein
The heat-sensitive recording layer and / or the heat-sensitive recording layer.
A heat-sensitive recording material characterized by being contained in a protective layer.