JP3094831B2 - Thermal recording medium - Google Patents

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 material utilizing a color-forming reaction between a color former and a color former, and more particularly to a recording image which is excellent in storage stability and light resistance against chemicals such as a plasticizer and has a surface gloss. The present invention relates to a heat-sensitive recording medium having a high stamping property and excellent stamping properties such as an aqueous stamp.

[0002]

2. Description of the Related Art Utilizing a color reaction between a color former and a color former,
A thermosensitive recording medium in which a recording image is obtained by contacting both color developing substances by heat is well known. Such a thermosensitive recording medium is relatively inexpensive, and its recording equipment is compact and easy to maintain, so that it is used not only as a recording medium for facsimile machines and various computers but also in a wide range of fields.

For example, as one of the fields of use, with the expansion of POS (point of sales) systems at retail stores and the like, the use of thermosensitive recording materials as labels for displaying products and the like is increasing. . Moreover, in recent years, there has been seen an example in which banners for advertisements, guidance, and the like are formed using a wide heat-sensitive plotter and are used for posting indoors or outdoors. The thermal recording material for labels and the thermal recording material for banners affixed to products are often exposed to room light or sunlight for a long period of time, and as a result, the background portion turns yellow. The product image may be significantly impaired. Therefore, there is a demand for a heat-sensitive recording medium in which the yellow color of the background portion is small when exposed to room light or sunlight.

Hitherto, a method has been proposed in which a finely pulverized ultraviolet absorber is added to the heat-sensitive recording layer or the protective layer in order to prevent yellowing of the background portion of the heat-sensitive recording medium due to light.
The use of a small amount of finely ground UV absorbers does not provide sufficient effects due to poor UV absorption efficiency, while the use of a large amount in the heat-sensitive recording layer causes background fog or decreases the recording density. There are new drawbacks.

[0005] In order to improve such background fog, a heat-sensitive recording medium in which a protective layer contains a microcapsule containing an ultraviolet absorber and having substantially no coloring ability is disclosed in JP-A-5-162442. As described in JP-A-5-177937, when the amount of microcapsules increases, the storage stability and surface gloss of a recorded image against chemicals such as a plasticizer decrease, and the protective layer containing microcapsules is formed of an aqueous stamp or the like. Have poor sealability.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording which is excellent in preservability and light fastness of a recorded image to chemicals such as a plasticizer, has a high surface gloss, and has excellent stamping properties such as an aqueous stamp. Is to provide the body.

[0007]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a semiconductor device comprising the steps of:
In a heat-sensitive recording layer comprising a colorless or pale-colored basic dye and a colorant capable of forming a color when contacted with the dye, and a heat-sensitive recording medium provided with a protective layer, the protective layer contains a liquid at room temperature.
Contains a benzotriazole-based UV absorber and has virtually no color-forming ability .
Total solids of the protective layer microcapsules having Ranaru wall film
20 to 60% by weight based on the amount , and epoxy-modified or
Uses amino- modified silicone oil for the total solids of the protective layer.
The above problem was solved and completed by adding 0.1 to 10% by weight .

[0008]

In the present invention, there is no particular limitation on the color forming system using the color former and the color former that constitute the heat-sensitive recording layer, and any combination that causes a color reaction by the heat energy from the thermal head is used. Is possible,
Examples thereof include a combination of a leuco dye and an acidic substance, a combination of a diazonium salt and a coupler, a combination of a chelate compound of a transition element such as iron and a coordination compound, and a combination of an aromatic isocyanate compound and an imino compound.

In particular, when the protective layer of the present invention is applied to a color forming system in which a leuco dye and an acidic substance are combined, the characteristics thereof are fully exhibited, and a heat-sensitive recording material having extremely excellent recording suitability can be obtained. Hereinafter, a color forming system using a leuco dye and an acidic substance will be described in detail. Various known leuco dyes are used for the heat-sensitive recording layer, and examples thereof include the following. 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
(N-ethyl-Np-tolyl) amino-7-N-methylanilinofluoran, 3,6-bis (diethylamino) fluoran-γ-anilinolactam, 3-diethylamino-6-methyl-7-chloro Fluorane, 3-diethylamino-7-chlorofluoran, 3- (N-ethyl-p-toluidino) -7-methylfluoran, 3-diethylamino-6,8-dimethylfluoran, 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-diethylamino-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-diethylamino-6-chloro-7-anilinofur Oran, 3-dibutylamino-6
Methyl-7-m-toluidinofluoran, 3-diethylamino-6-methyl-7-p-ethoxyanilinofluoran, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methyl Amino) -3′-methylspiro [phthalide-3,9′-xanthen-2′-ylamino] phenyl} propane, 3-diethylamino-7- (m-trifluoromethylphenyl) aminofluoran, 3,3-bis [ 1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5
6,7-tetrachlorophthalide and the like. Of course, the invention is not limited to these, and two or more of them can be used in combination as needed.

Various acidic substances used in combination with the leuco dyes described above are known, for example, 4,4'-isopropylidene diphenol, 1,1
-Bis (4-hydroxyphenyl) cyclohexane,
2,2-bis (4-hydroxyphenyl) -4-methylpentane, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy -4'-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxyphenyl-4'-benzyloxyphenyl sulfone, 3,4- Dihydroxyphenyl-4′-methylphenylsulfone, bis (4-hydroxyphenylthioethoxy) methane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane,
Phenolic compounds such as 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene and 1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene N- (p-toluenesulfonyl) carbamoyl-p-cumylphenyl ester, N
-(P-toluenesulfonyl) carbamoyl acid-p-benzyloxyphenyl ester, N- (o-toluoyl) -p-toluenesulfonamide, N- (p-toluenesulfonyl) -N '-(p-tolyl) urea Having a —SO ₂ NH— bond in its molecule, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate,
Zinc salts of salicylic acid derivatives such as-[3- (p-tolylsulfonyl) propyloxy] salicylate and 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate.

The ratio of the leuco dye to the acidic substance is appropriately selected depending on the type of the leuco dye or the acidic substance to be used, and is not particularly limited, but is generally 1 to 1 part by weight of the leuco dye. -10 parts by weight, preferably 2
About 5 parts by weight of an acidic substance is used. Paints for heat-sensitive recording layers containing these substances generally use water as a dispersion medium,
It is prepared by separately dispersing the leuco dye and the acidic substance using a stirring / pulverizer such as a ball mill, an attritor, and a sand mill.

In the coating solution, an aqueous resin is used as an adhesive, for example, starches, hydroxyethyl cellulose,
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 Combined salt, ethylene
At least one of an acrylic acid 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, based on the total solid content of the recording layer 5-3
It is blended in the range of about 0% by weight.

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, a pigment and the like are appropriately added.

Specific examples of the pigment include, for example, kaolin,
Clay, calcium carbonate, calcined clay, calcined kaolin,
Examples include inorganic pigments such as titanium oxide, diatomaceous earth, 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, ethylenebisstearic acid amide, behenic acid amide, methylenebisstearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate,
2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, 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,
Examples thereof include 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 in a range of about 4 parts by weight or less based on 1 part by weight of the leuco dye.

In the present invention, it is possible to add a storability improving agent to the heat-sensitive recording layer. Examples of such a preservability improver include the following. 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 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 ′ Hindered phenol compounds such as -thiobis (3-methylphenol), 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 4,4'-diglycidyloxydiphenyl sulfone, and 4-benzyloxy- 4 ′-(2-methylglycidyloxy) diphenyl sulfone, cresol novolak type epoxy resin, phenol novolak type epoxy resin, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis (4 Sodium or polyvalent metal salt of 6-di-tert-butylphenyl) phosphate, bis (4-ethyleneiminoca) Rubonylaminophenyl) methane and the like. Among them, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl)
Butane is preferably used because it has an excellent effect on water resistance and hardly causes background fog.

As described above, the present invention provides a microcapsule, a modified silicone oil, and a water-soluble microcapsule which contain an ultraviolet absorber and have substantially no color-forming ability on a heat-sensitive recording layer containing at least a color former and a color former. It has a significant feature in that a protective layer containing a conductive polymer is provided. Specific examples of the aqueous resin used for such a protective layer include the following substances.

Starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose,
Gelatin, casein, gum arabic, fully or partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-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, At least one of an amide resin and a polyurethane resin is blended in a range of about 10 to 90% by weight based on the total solid content of the protective layer. Among them, polyvinyl alcohol-based resins are preferred because of their excellent film-forming properties.

As the ultraviolet absorber encapsulated in the microcapsules, various known ones can be used. Among them, a benzotriazole ultraviolet absorber is preferable in view of the ultraviolet absorption efficiency. When synthesizing oil-in-water type microcapsules, it is not necessary to dissolve the ultraviolet absorber in the organic solvent, so it can be contained in the microcapsules at a high concentration, and the ultraviolet absorbing ability is also significantly improved. More preferably used. Specific examples of the ultraviolet absorber include, for example, the following.
2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-undecyl-5'-methylphenyl) benzotriazole, 2- [2'- Hydroxy-4'-
(1 ″ -propylhexyl) oxyphenyl] benzotriazole, ethylene glycol and methyl-3- [3-
(2H-benzotriazol-2-yl) -5-tert-
[Butyl-4-hydroxyphenyl] propionate, phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, 2,4-
Dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole, 2- (2'-
(Hydroxy-5'-tert-butylphenyl) benzotriazole, 2'-ethylhexyl-2-cyano-3,
3'-diphenyl acrylate, ethyl-2-cyano-
3,3'-diphenyl acrylate and the like.

The microcapsules used in the present invention can be prepared by various known methods. Generally, a solution (oil-based liquid) mainly containing an ultraviolet absorbent as described above is emulsified and dispersed in an aqueous medium to obtain an oil-based liquid. It is prepared by a method of forming a wall film made of a polymer substance around a droplet.

As a polymer substance to be a wall film of a microcapsule, a microcapsule having a wall film made of a polyurethane resin or a polyurea resin is excellent in heat resistance. Therefore, when used in a protective layer of a thermosensitive recording medium, In addition to the effect of inorganic pigment added to the protective layer to prevent sticking to the thermal head, it has an excellent collateral effect, and it is more refracted than microcapsules consisting of other wall films or ordinary pigments. Since the ratio is low and the shape is spherical, it is preferably used because even if it is incorporated in a large amount in the protective layer, there is no danger of causing a decrease in the density of a recorded image (so-called whitening phenomenon) due to irregular reflection of light. In addition, the microcapsules having a wall film made of an aminoaldehyde resin are easy to adjust the thickness of the wall film in addition to the above heat resistance,
It is preferably used particularly when strength is required.

The microcapsules having a polyurethane / polyurea resin wall film can be used in a core material to encapsulate a capsule wall film agent such as a polyvalent isocyanate and a polyol which reacts with the polyisocyanate, or an adduct of a polyvalent isocyanate and a polyol. , And emulsified and dispersed in an aqueous medium in which a protective colloid substance such as polyvinyl alcohol is dissolved, and the polymer temperature is raised to cause a polymer formation reaction at an oil droplet interface.

As the polyvalent isocyanate, for example, 1,
4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,3- or 1,4-diisocyanatecyclohexane, 1,3- or 1,4
-Bis (isocyanatomethyl) -cyclohexane, 3
-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), dicyclohexylmethane-4,4-diisocyanate, isopropylidene-bis (4-cyclohexyl)
Examples include isocyanate, 1,3- or 1,4-xylylene diisocyanate, tetramethyl xylylene diisocyanate, 4,4-bis (isocyanatomethyl) -diphenylmethane, and the like.

Examples of the polyol compound used in combination with the microcapsule wall film agent include ethylene glycol, 1,3-propanediol, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanone. Diol, 2,4-pentanediol, 1,1,1-trimethylolpropane, 1,4-di (2-hydroxyethoxy) benzene, 1,3-di (2-hydroxyethoxy)
Benzene, p-xylylene glycol, m-xylylene glycol, 4,4′-dihydroxydiphenylmethane, 4,4′-isopropylidenediphenol, 4,
4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-isopropylidene diphenol, and the like.

Of course, the polyvalent isocyanate compound and the polyol compound are not limited to the above compounds, and two or more kinds can be used in combination as needed.

The amount of the ultraviolet absorber used in the microencapsulation should be appropriately selected according to the type of the ultraviolet absorber and the organic solvent to be used, and is not particularly limited. In the case of a polyurethane / polyurea resin, it is preferably 3 to 80% by weight, and more preferably 10 to
It is desirable to blend the ultraviolet absorbent in an amount of about 80% by weight.

Microcapsules having an aminoaldehyde resin wall film are generally made of at least one of urea, thiourea, alkyl urea, ethylene urea, acetoguanamine, benzoguanamine, melamine, guanidine, buret, cyanamide, hexamethylenetetraamine and the like. And at least one aldehyde such as formaldehyde, acetaldehyde, paraformaldehyde, glutaraldehyde, glyoxal, and furfural, or an initial condensate obtained by condensing them. You. The amount of the capsule wall film agent of the microcapsule having the amino aldehyde resin wall film is 30 to 300 with respect to the capsule core material.
%, Preferably in the range of 35 to 200% by weight.

As an emulsifier (protective colloid agent) used for microencapsulation, various anions, nonions, cations or amphoteric water-soluble polymer compounds are used.

The average particle size of the microcapsules used in the present invention is 0.1 to 3 μm, preferably 0.3 to 2.5 μm in consideration of the absorption efficiency of ultraviolet rays and the quality of recorded images.
It is desirable to adjust so as to be within the range. Also,
The amount of the microcapsules to be incorporated into the protective layer is to be appropriately selected depending on the type of the ultraviolet absorber and the concentration in the capsule, and furthermore, the intended quality, etc., and is generally based on the total solid content of the protective layer. It is desirably adjusted in the range of about 5 to 80% by weight, preferably about 20 to 60% by weight.
When the content is less than 5% by weight, the recording traveling property is reduced, and the content is 80% by weight.
If it exceeds, the gloss of the surface decreases.

The amount of the ultraviolet absorber used in the present invention is not particularly limited, but it is preferable that the ultraviolet absorber is present in the protective layer of the thermosensitive recording medium in an amount of 0.1 to 3.0 g / m ^2. Preferably, more preferably 0.2 to 2.0
It is preferable to adjust within the range of g / m ² . 0.1 g of ultraviolet absorber contained in microcapsules in the protective layer
If it is less than / m ^2, the effect of preventing the background portion of the thermal recording medium from yellowing is reduced. If it exceeds 3.0 g / m ² , the protective layer is inevitably thick, so that the recording sensitivity is lowered. When the amount of the ultraviolet absorber is less than 10% by weight based on the total amount of the ultraviolet absorber, the microcapsule wall film agent, and the organic solvent that can be used in combination as required, the yellowing of the background portion of the heat-sensitive recording medium is prevented. In order to exert the effect, the coating amount of the microcapsule must be increased, so that the protective layer is inevitably thickened and the recording sensitivity is reduced.

The modified silicone oil used for the protective layer is, for example, a modified silicone in which an epoxy group, a carboxyl group, an amino group, a hydroxyl group, an acetoacetyl group or the like is introduced into a side chain or a terminal such as dimethylpolysiloxane or hydrogenpolysiloxane. Oil is used. Among them, epoxy-modified silicone oil or amino-modified silicone oil is preferable because a uniform coated surface can be obtained.
These hydrophobic silicone oils can be used after emulsification or by introducing a hydrophilic group such as a polyether group into a group other than the epoxy group, and making the group water-soluble. Specific examples of such a modified silicone oil include SM8715 manufactured by Toray Silicone Co., Ltd., PolonMF-11B manufactured by Shin-Etsu Chemical Co., Ltd., and Polon M
Epoxy-modified silicone oil emulsions such as F-18, Toray Silicone SF-8421, BY16-845, BX16
-863, BX16-864, BX16-865 and other epoxy polyether-modified silicone oils, SM-870 manufactured by Toray Silicone
2, SM-8709, Shin-Etsu Chemical Polon MF-14, Poln
Amino-modified silicone oil emulsions such as MF-14D and Poln MF-14E. The amount of the modified silicone oil to be used is not particularly limited, but is 0.1 to 10% by weight, preferably 0.1 to 10% by weight, based on the total solid content of the protective layer.
It is used in the range of 2 to 5% by weight. If the amount of these modified silicones is less than 0.1% by weight, the desired effects of the present invention cannot be obtained, and if the amount is 10% by weight.
Exceeding the range may cause pinholes in the protective layer called cissing when coating the protective layer, which may cause problems such as the inability to fulfill the intended purpose of the protective layer.

In the protective layer, a pigment can be added as needed 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. It is generally desirable to adjust the amount of use in the range of about 5 to 300% by weight based on the aqueous resin.

The method for preparing the coating liquid for forming the protective layer is not particularly limited. In general, water is used as a dispersion medium, and the above-mentioned specific microcapsules (dispersion liquid), aqueous resin, pigments added as necessary, and the like are used. Are mixed. 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.

In the present invention, the method of forming the heat-sensitive recording layer and the protective layer is not particularly limited, and can be formed according to a conventionally known and commonly used technique.
After applying and drying the coating liquid for the recording layer on the support by an appropriate coating method such as pure blade coating, rod blade coating, short dwell coating, curtain coating, and die coating, the coating liquid for the protective layer is further subjected to thermal recording. It is formed by a method of applying and drying on the layer. The support is appropriately selected from paper obtained by neutral papermaking or acidic papermaking, plastic film, synthetic paper, nonwoven fabric, metal deposit, and the like. The coating amount of the heat-sensitive recording layer coating liquid is ² to 12 g / m ² , preferably 3 to 10 g / m ^{2 on} a dry weight basis.
m ² approximately, the coating amount of the protective layer coating composition is 0.1 dry weight
20 g / m ^2, is preferably adjusted in the range of about 0.5 to 10 g / m ^2.

The heat-sensitive recording medium of the present invention has a back surface layer on the side opposite to the heat-sensitive recording layer, which protects the heat-sensitive recording layer from the influence of a plasticizer or the like from the back side, or corrects curl and re-wet adhesive. Can be provided. Further, in the heat-sensitive recording material manufacturing field, such as providing an undercoat layer on the support, applying a smoothing treatment such as super calendaring after coating each layer, or applying an adhesive treatment to the back surface of the recording material to process it into an adhesive label. Various known techniques can be added as needed.

[0036]

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. Parts and% in Examples are parts by weight and% by weight, respectively, unless otherwise specified. [Example 1] Preparation of solution A 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 1 μm.

Solution B Preparation of a composition comprising 30 parts of 4-hydroxy-4′-isopropoxydiphenylsulfone, 5 parts of a 5% aqueous solution of methylcellulose and 80 parts of water has a mean particle size of 1 using a sand mill.
Milled to a μm.

Solution C Preparation 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 by a sand mill until the average particle diameter became 1 μm.

Formation of heat-sensitive recording layer 55 parts of solution A, 115 parts of solution B, 80 parts of solution C, 80 parts of a 10% aqueous solution of polyvinyl alcohol, and calcium carbonate 3
Five parts were mixed and stirred, and the obtained coating solution was applied and dried on one surface 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.

Solution D Preparation 220 parts of a 12% aqueous solution of acetoacetyl group-modified partially saponified polyvinyl alcohol (trade name: Gosefimer Z-210, manufactured by Nippon Synthetic Chemical Co., Ltd.) is added to a stirring and mixing vessel equipped with a heating device. And an aqueous medium for capsule production. Separately, 2- (2'-hydroxy-3'-dodecyl-5'-
Methylphenyl) benzotriazole (trade name: Tinuvin 171, manufactured by Ciba-Geigy Corporation) 77 parts, hexamethylene diisocyanate trimer (isocyanurate type)
[Trade name: Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd.] A solution obtained by heating, mixing and stirring 33 parts up to 40 ° C. in the above aqueous medium for producing capsules was mixed with a TK homomixer [Model HV-M, special (Manufactured by Kika Kogyo Co., Ltd.) while emulsifying and dispersing while cooling so that the average particle diameter becomes 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.

Formation of protective layer 150 parts of D solution adjusted to a solid concentration of 25%, 250 parts of a 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol [trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Co., Ltd.] 3 parts of epoxy-modified silicone oil emulsion [trade name: Polon MF-11B, manufactured by Shin-Etsu Chemical Co., Ltd., solid content concentration 31%], kaolin [trade name: UW-90, EM
Company C] 15 parts, 2 parts of a 5% aqueous solution of glyoxal, 6 parts of a 30% dispersion of zinc stearate, and 30 parts of water are mixed and agitated to obtain a coating liquid obtained by the above-mentioned thermal recording. The coating was applied onto the layer so that the coating amount after drying was 3 g / m ² , dried, and then smoothed with a super calender to obtain a thermosensitive recording medium having a protective layer.

Example 2 In forming the protective layer of Example 1, an epoxy-modified silicone oil emulsion [trade name: Polon MF-11B, manufactured by Shin-Etsu Chemical Co., Ltd., having a solid content of 3]
Example 1 except that 3 parts of an amino-modified silicone oil emulsion [Polon MF-14D, manufactured by Shin-Etsu Chemical Co., Ltd., solid content concentration 30%] was used instead of 3 parts of [1%].
In the same manner as in the above, a thermosensitive recording medium was obtained.

Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that D liquid 250 was used instead of 150 parts of D liquid in forming the protective layer of Example 1.

Example 4 In forming the protective layer of Example 1, 250 parts of a 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol (trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Co., Ltd.) and glyoxal were used. 10% of fully saponified polyvinyl alcohol [trade name: PVA-117, manufactured by Kuraray Co., Ltd.] instead of 2 parts of a 5% aqueous solution of
A thermosensitive recording medium was obtained in the same manner as in Example 1, except that 250 parts of an aqueous solution and 2 parts of a 5% aqueous solution of boric acid were used.

Example 5 In the formation of the protective layer of Example 1, an epoxy-modified silicone oil emulsion [trade name: Polon MF-11B, manufactured by Shin-Etsu Chemical Co., Ltd., solid content 3
1%] 3 parts of epoxy-modified silicone oil emulsion [Polon MF-11B, manufactured by Shin-Etsu Chemical Co., Ltd., solid content concentration 31%] was used in the same manner as in Example 1 except that 15 parts were used. A thermosensitive recording medium was obtained.

[ Reference Comparative Example 1 ] In forming the protective layer of Example 1, instead of 3 parts of an epoxy-modified silicone oil emulsion [Polon MF-11B, manufactured by Shin-Etsu Chemical Co., Ltd., solid content: 31%] , Epoxy-modified silicone oil emulsion [Product name: Po
lon MF-11B, manufactured by Shin-Etsu Chemical Co., Ltd., solid content concentration 31%] 4
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 0 part was used.

Comparative Example 1 An epoxy-modified silicone oil emulsion [Polon MF-11B, Shin-Etsu Chemical Co., Ltd., solid content 3
1%], except that 3 parts of water were used instead of 3 parts.
In the same manner as in the above, a thermosensitive recording medium was obtained.

Comparative Example 2 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that 150 parts of a kaolin dispersion having a solid concentration of 25% was used instead of 150 parts of Solution D adjusted to a solid concentration of 25%. Obtained.

Comparative Example 3 Preparation of Solution H A composition comprising 10 parts of 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 5 parts of a 5% aqueous solution of methylcellulose, and 35 parts of water was averaged with a sand mill. It was pulverized until the particle diameter became 1.5 μm.

Formation of Protective Layer A heat-sensitive recording material was obtained in the same manner as in Example 1, except that 150 parts of the D liquid was used instead of 150 parts of the D liquid in the formation of the protective layer of the first embodiment.

The thermal recording medium thus obtained was subjected to the following quality evaluation tests, and the results are shown in Table 1. [Glossiness] The glossiness was measured with a variable angle photometer at an incident angle of 75 °. [Coloring Density] Each thermosensitive recording medium was colored with an applied energy of 0.45 mJ / dot using a thermal evaluation device (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), and the color density of the obtained recorded image was determined as Macbeth density. It was measured in visual mode with a total meter [RD-914, manufactured by Macbeth Co.].

[Light Resistance] The initial density of the background portion of the thermal recording medium after recording by the above method and the density of the background portion after exposure to direct sunlight for 5 days were measured with a Macbeth densitometer (using a blue filter). did. [High-temperature and high-humidity resistance] The thermosensitive recording medium after recording by the above method was heated at 50 ° C and 75% R.
Color density and background density after standing for 24 hours in H
It was measured with a Macbeth densitometer (visual mode) to evaluate the high temperature and high humidity resistance.

[Plasticizer resistance] A wrap film (trade name: KMA-W, manufactured by Mitsui Toatsu Chemicals, Inc.) is wound three times on a polycarbonate pipe (40 mmφ pipe), and the above-mentioned [coloring property] The thermosensitive recording medium recorded by the above method is placed, and a wrap film is further wound three times on the thermosensitive recording medium, and the color density after leaving at 40 ° C. for 24 hours is measured with a Macbeth densitometer (visual mode).
The plasticizer resistance was evaluated.

[Appropriateness of Stamp] A stamp was printed on the surface of the protective layer with an aqueous stamper aqueous stamp ink, and then allowed to stand for 2 hours. The degree of ink bleeding was visually evaluated. "Evaluation criteria" ：: There is no bleeding of the stamp ink, and it is extremely excellent. ：: There is almost no bleeding and there is no practical problem. Δ: Bleeding can be confirmed, and the stamped characters and the like are difficult to confirm. ×: The stamp ink bleeds and reading after evaluation is difficult.

[0055]

[Table 1]

[0056]

As is clear from the results shown in Table 1, the heat-sensitive recording media of the present invention are all excellent in light resistance, have very little discoloration of the background, and have high gloss. The heat-sensitive recording material was excellent in suitability such as an aqueous stamp.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-178804 (JP, A) JP-A-3-67888 (JP, A) JP-A-3-57693 (JP, A) JP-A-3-376 61077 (JP, A) JP-A-5-221135 (JP, A) JP-A-5-305230 (JP, A) JP-A-5-162442 (JP, A) JP-A-5-184909 (JP, A) JP-A-6-305254 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34 B01J 13/02

Claims (1)

(57) [Claims] To 1. A on a support, a thermosensitive recording layer containing a color former and color developer, and heat-sensitive recording material a protective layer sequentially provided containing an aqueous resin, in the protective layer, at ambient temperature of the liquid base
It contains an azotriazole-based UV absorber and has virtually no color-forming ability and is made of polyurethane / polyurea resin.
That 20 to 60% by weight of microcapsules with respect to the total solid content of the protective layer having a wall film, and is contained from 0.1 to 10 wt% based on the total solids content of the protective layer of an epoxy-modified or amino-modified silicone oil A heat-sensitive recording material characterized in that: