JPH0767859B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a heat-sensitive recording material, which retains excellent qualities such as color developability, water resistance, plasticizer resistance, oil resistance, and the like, and also has glossiness on the printed surface. The present invention relates to a heat-sensitive recording material which is improved.

[Prior Art] Thermal recording materials are generally formed on a support such as paper, synthetic paper, or plastic film by using a color-forming substance such as an electron-donating leuco dye and an organic acid substance such as an electron-accepting phenolic compound. It is possible to obtain a recorded image by providing a thermosensitive coloring layer containing a color-developing substance as a main component and reacting them with thermal energy. Thermal recording materials are compact, inexpensive, and easy to maintain,
It is widely used in the output of electronic computers, facsimiles, automatic ticket vending machines, printers of scientific measuring machines, and printers for CRT medical measurement.

However, since the conventional heat-sensitive recording material is coated with only a heat-sensitive layer containing a color-forming dye substance, a color-developing substance and a binder as an active ingredient on a support, light, water, temperature, a plasticizer and an oil are used. Since it is unstable with respect to, etc., changes with time during storage are always a problem. Further, such a heat-sensitive recording material has the disadvantage that the glossiness of the image area and the non-image area is considerably low because the above-mentioned materials are the main components.

In order to improve such storability in the conventional thermosensitive recording material, it has been proposed to provide a surface layer on the thermosensitive coloring layer. For example, JP-A-56-146794 and 54-128347.
Japanese Patent Application Laid-Open No. 56-125354, 61-32
No. 790, 60-260382, etc. using a water-soluble polymer compound such as polyvinyl alcohol, or water-soluble on the thermosensitive coloring layer as seen in JP-A-58-199189. It has been reported that a polymer compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer, and a surface layer made of an oil-based paint containing a hydrophobic polymer compound as a resin component is provided thereon. However, since these use a water-soluble polymer compound or a hydrophobic polymer compound emulsion in the intermediate layer or the surface layer, they are not sufficiently satisfactory in water resistance and moisture storage stability,
In addition, the actual situation is that the image area and the non-image area do not have sufficient gloss.

[Problems to be Solved by the Invention] An object of the present invention is to solve these problems and to have long-term storage properties such as water resistance, plasticizer resistance, and oil resistance, and a gloss equivalent to that of silver salt printing paper. The object of the present invention is to provide a heat-sensitive recording material to which the degree is given. As a result, for example, when it is used as a thermal recording type printer paper for CRT images, of course, it is used for coupons and commuter tickets that require preservability, and perishable food products and oil types by POS bar code pricing system. Not only is it suitable for use as label paper that is attached to the packaging surface when it is wrapped in polyvinyl chloride film such as meat, which contains a lot of meat, but also provides thermal recording materials that can be used as fax paper or printer paper for long-term storage. Is what you are trying to do.

[Means for Solving the Problems] The inventors of the present invention provided a thermosensitive coloring layer having a coloring dye substance and a color-developing substance on a support such as paper, synthetic paper, and plastic film, on which a water-soluble coloring layer was formed. Photographic paper of silver salt by providing an intermediate layer containing a hydrophilic polymer substance, an inorganic pigment, a cross-linking agent, and a plastic pigment, and providing a gloss layer containing a glossy hydrophobic polymer compound as a main component through this intermediate layer. It has been found that a heat-sensitive recording material having the same degree of glossiness as can be obtained. The heat-sensitive recording material of the present invention comprises an intermediate layer and a gloss layer, which are sequentially formed on a heat-sensitive color-forming layer provided on a support.

The intermediate layer is formed of a water-soluble polymer substance, a cross-linking agent, an inorganic pigment and a pigment containing a plastic pigment as a main component, and improves surface gloss, water resistance, plasticizer resistance, and oil resistance. That is the purpose.
With the improvement of these properties, adverse effects of water, plasticizers, oils, etc., deterioration of surface glossiness, for example, fading of the color-developed portion can be reliably avoided, and the glossiness of the non-image area and the image area is improved. be able to.

As the water-soluble polymer substance, a polyvinyl alcohol resin or a substance having a barrier property such as casein can be used. As the polyvinyl alcohol resin, polyvinyl alcohol having any degree of polymerization and saponification can be used. Further, it is copolymerized with unsaturated carboxylic acid or its partial or complete ester, salt, anhydride, nitrile, amide, unsaturated sulfonic acid or its salt, α-olefin having 2 to 30 carbon atoms, vinyl ether, saturated branched fatty acid vinyl, etc. Modified polyvinyl alcohol and urethane, acetalization, etherification, grafting, phosphate esterification,
A modified polyvinyl alcohol that has been sulfated or the like can also be used. The degree of polymerization is preferably in the range of 300 to 1700, and particularly preferably in the range of 500 to 1000 from the viewpoint of coating viscosity and coating property. In addition, a cross-linking agent and an anti-stick agent, and a pigment for melt absorption of the gloss layer can be included. Regarding this, it is particularly suitable to use the same one as used in the thermosensitive coloring layer.

As the plastic pigment, use is made of polystyrene-based plastic pigment, styrene / butadiene-based plastic pigment, acrylic / styrene copolymer-based plastic pigment, urea / formalin-based plastic pigment, nylon powder, polyethylene powder, etc., which improve the glossiness. it can. Particle size
It is preferably 2.0 μm or less, and particularly preferably in the range of 0.1 to 1.0 μm from the viewpoint of surface gloss. The shape of the particles is not particularly limited, and conventionally known shapes can be used, and for example, spherical, donut-shaped, hollow sphere-shaped, or the like plastic pigments can be blended.

In the present invention, a gloss layer for imparting high gloss is formed on the intermediate layer thus formed. The gloss layer contains a glossy hydrophobic polymer compound and a lubricant as main components. The hydrophobic polymer compound can be used as an organic solvent solution, and may be in the form of emulsion. put it here,
In the case of "glossiness", when the glossiness is measured by coating on the intermediate layer, a glossiness of 70% or more gives excellent results.

Examples of such hydrophobic polymer compounds include copolymers of acrylic acid ester and / or methacrylic acid ester and styrene and / or vinyl acetate, other alkyd resins, urea resins, melamine resins, benzoguanamine resins, chroman resins, Epoxy resin, methyl vinyl ether-maleic anhydride copolymer, ketone resin,
A general organic solvent solution or emulsion of phenol resin, polystyrene, polyester, styrene-maleic anhydride copolymer, silicone resin, unsaturated polyester resin or the like can be used. By using an emulsion, it can be formed as an aqueous paint.

Lubricants are those added to improve sticking, head residue, and the like to provide thermal head compatibility, such as higher fatty acid metal salts, microcrystalline wax, and acid phosphate esters of polyoxyethylene alkyl ether. Phosphoester compounds (including alkyl phosphate ester), phospholipids such as fatty acid ester, lecithin, kephalin, riboinositol, sphingomyelin, and heat-soluble substances (lubricants) used in the thermosensitive coloring layer, and other release agents Is blended. In this case, the coating amount of the coating material for forming the glossy layer is preferably 10 g / m ² or less as a dry weight, and particularly preferably 0.05 to 10.0 g / m ² in terms of glossiness, sensitivity and stick suitability.

As the support for the thermal recording material, paper such as high-quality paper, medium-quality paper, art paper, cast coated paper, paperboard and thin paper is generally used, as well as plastic film, synthetic paper, laminated paper, aluminum foil, etc. Can be used.

Examples of the color-forming dye substance to be used in the thermosensitive color-forming layer formed on the surface of such a support include 2,2-bis {4-
[6 '-(N-cyclohexyl-N-methylamino)-
3'-methyl spiro [phthalide-3,9'-xanthene]
-2'-ylamido] phenyl} propane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-
Biperidino-6-methyl-7-anilinofluorane, 3
-(N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-
7-chloroanilinofluorane, 3- [N-ethyl-N
-(P-Methylphenyl) amino] -6-methyl-7-
Anilinofluorane, 3-diethylamino-7- (metatrifluoromethyl) anilinofluorane, 3- [N-
Ethyl-N-tetrahydrofurfuryl] amino-6-methyl-7-anilinofluorane, 3- [N-ethyl-N
-Isopentyl] amino-6-methyl-7-anilinofluorane, 3- [N, Ndibutyl] amino-6-methyl-
Typical examples are fluoran dyes such as 7-anilinofluorane.

The color-developing substance may be any as long as it is liquefied or vaporized at room temperature or higher, preferably 70 ° C. or higher, and reacts with the color-forming dye to develop a color, for example, 4,4′-isopropylidenediphenol ( Bisphenol A], 4,4'-
Isopropylidene bis (2-chlorophenol), 4,
4'-isopropylidene bis (2-methylphenol), 4,4'-isopropylidene bis (2,1-tert-butylphenol), 4,4'-sec-butylidene diphenol, 4,4'-cyclohexylidene Phenol, 4-tert
-Butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, naphthol, β-naphthol, methyl-4-hydroxybenzoate, 4-hydroxy-acetophenone, salicylate anilide, novolac type phenol resin, halogenated novolac type phenol resin, 4 , 4'-thiobis (3-methyl-6-tert-butylphenol), propyl p-hydroxybenzoate, isopropyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-hydroxybenzoic acid Aliphatic carboxylic acids such as methylbenzyl, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, stearic acid, benzoic acid, p-tert
-Butylbenzoic acid, phthalic acid, gallic acid, salicylic acid,
3-isopropylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, bis (4-hydroxyphenyl) sulfide, 1,7-di (4-hydroxyphenylthio)-
3,5-dioxaheptane, p-nitrobenzoic acid, salts of these organic developers with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel, 4,4′- Dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 3,
3'-dihydroxydiphenyl sulfone, 3,3'-diamino-4,4'-dihydroxy-diphenyl sulfone, 3,3 '
-Diallyl-4,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-diphenyl sulfone, 4-
Hydroxy-4'-isopropyldiphenyl sulfone,
4-hydroxy-4'isopropyloxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 2,4-dihydroxy-diphenyl sulfone, 2,4-dihydroxy-4'-methyldiphenyl sulfone, 3,4-dihydroxy Phenyl-p-trisulfone and the like can be mentioned. The color-developing substance is usually used in an amount of 1 to 5 parts by weight, preferably 1.5 to 3 parts by weight, based on 1 part by weight of the color forming dye substance.

As the binder for the thermosensitive coloring layer, all known binders can be used. However, when mixed with the respective dispersions of the color forming dye substance and the color developing substance, it is preferable that the liquid does not develop color, aggregate, or have a high viscosity, and the heat-sensitive recording sheet It is required that the formed film of No. 1 be strong, have no desensitizing action, and be appropriate with respect to the above-mentioned sticking.

Usual aqueous binders include polyvinyl alcohol, modified starch, gum arabic, gelatin, methylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, polyvinylpyrrolidone, polyacrylic acid salts, polyacrylic amide, styrene-maleic anhydride copolymer,
Methyl vinyl ether-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer, styrene-butadiene latex, acrylic acid ester copolymer emulsion and the like can be used. In order to impart water resistance to the coating film,
A combination of a water-soluble polymer substance containing a reactive group such as an acetoacetyl group, a carboxyl group, an amide group and the like and a crosslinking agent is preferable.

As the cross-linking agent, glyoxal, dialdehydes such as polyaldehyde, polyamines such as polyethyleneamine, epoxy, polyamide resin, diglycidyl dimethyl roll urea such as glycerin diglycidyl ether, other ammonium persulfate and ferric chloride, A known compound such as magnesium chloride is used. Examples of the pigment include calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, and surface-treated calcium carbonate, An inorganic fine powder such as silica can be used.

In addition to the above, if necessary, auxiliary additive components such as fillers, surfactants, heat-fusible substances (or lubricants), etc. that are commonly used in heat-sensitive recording materials of this type are further added to the heat-sensitive color forming layer. That doesn't matter. Examples of the heat-fusible substance include fatty acid amides such as stearic acid amide, stearic acid ethylenebisamide, oleic acid amide, palmitic acid amide, palm fatty acid amide, and behenic acid amide, zinc stearate, calcium stearate, polyethylene wax, and carnauba wax. , Waxes such as paraffin wax, ester wax, dimethyl terephthalate,
Terephthalic acid dibutyl ester, terephthalic acid dibenzyl ester, isophthalic acid dibutyl ester, 1-hydroxynaphthoic acid phenyl ester, 1,2-di (3-methylphenoxy) ethane, 1,2-diphenoxyethane,
1-phenoxy-2- (4-methylphenoxy) ethane, diphenyl carbonate, p-benzylbiphenyl, 2,2 '
-Methylenebis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (6-t-butyl-3-)
Methylphenol), 1,1,3-tris (2-methyl-4)
-Hydroxy-5-t-butylphenyl) butane, 2,
2'-methylenebis (4-ethyl-6-t-butylphenol), 2,4-di-t-butyl-3-methylphenol, 4,4'-thiobis (3-methyl-6-t-bitylphenol) Hindered phenols such as 2- (2'-
Examples thereof include sensitizers such as hydroxy-5'-methylphenyl) benzotriazole and 2-hydroxy-4-benzyloxybezophenone, and various heat-fusible substances such as lubricants, antioxidants, and UV inhibitors. In general, the amount of the heat-fusible substance added is preferably 4 parts by weight or less with respect to 1 part by weight of the color-developing substance.

[Examples] The present invention will be described in more detail with reference to examples below, but is not of course limited thereto. Parts in each example indicate parts by weight.

Example 1 (1) Preparation of solution A 3- (N-ethyl-N-cyclohexylamino) 6-methyl-7-anilinofluorane 8 parts 10% aqueous solution of polyvinyl alcohol 5 parts water 13 parts (2) Preparation of solution B 2 , 4'-Dihydroxy-diphenyl sulfone 17 parts 10% polyvinyl alcohol aqueous solution 10 parts water 20 parts (3) C solution preparation 10% polyvinyl alcohol aqueous solution 60 parts (Gothenal T-350: manufactured by Nippon Synthetic Industry Co., Ltd.) 30% polyamide resin 4 parts (Sumiraz Resin 633: Sumitomo Chemical Co., Ltd.) 50% calcium carbonate aqueous dispersion 10 parts (PC-700: Shiraishi Industrial) 45% acrylic / styrene plastic pigment aqueous dispersion (ROHM & HAAS JAPAN Co., Ltd.) : OP−42
M: 0.55μ sphere) 5 parts Water 30 parts (4) Preparation of solution D 40% Methyl methacrylate / styrene copolymer toluene solution 45 parts (Dencarac # 790: manufactured by Denki Kagaku Kogyo) 10% Lecithin-toluene solution 9 parts Toluene 27 parts The above liquids A and B are separately dispersed and ground by a sand glider until the average particle size becomes 1 μm or less, and C
The liquid, the liquid D, and the liquid E were stirred for 15 minutes with a solid-liquid stirrer.

(5) Formation of thermosensitive coloring layer A liquid 15 parts B liquid 52 parts 60% clay water dispersion liquid 24 parts (UW-90: manufactured by Ryosan Corporation) 10% polyvinyl alcohol aqueous solution 60 parts 25% zinc stearate 3 parts 10% Glyoxal 3 parts (Gauzezar P: manufactured by Nippon Synthetic Chemical Industry) Mix in the above proportions to prepare a coating solution. This coating solution was applied on a base paper of 50 g / m ^{2 so} that the dry weight was 8 g / m ² , and then super calendering treatment was performed to provide a thermosensitive coloring layer having a Bekk smoothness of 550 seconds.

(6) Formation of Intermediate Layer Liquid C was applied onto the color-developing layer so that the dry weight was 3 g / m ^2, to provide an intermediate layer.

(7) Formation of gloss layer Liquid D was coated on the above-mentioned intermediate layer so that the dry weight was 4 g / m ² , and a gloss layer was provided to produce a heat-sensitive recording material having a four-layer structure.

Example 2 Instead of the pigment calcium carbonate of the liquid C (intermediate layer paint) used in Example 1, 210 ml / 100 g of oil absorption, apparent specific volume of 3 ml /
A heat-sensitive recording material having a four-layer structure was produced in the same manner as in Example 1 except that the same amount of ultrafine silica powder (Mizukasil: manufactured by Mizusawa Chemical Co., Ltd.) having an average particle size of 1.2 μm was used.

Example 3 In the liquid C (intermediate layer paint) used in Example 1, a polystyrene plastic pigment (made by Asahi Kasei Kogyo: L-88) was used as an acrylic / styrene plastic pigment.
A thermosensitive recording material having a four-layer structure was produced in the same manner as in Example 1 except that the same amount of (01: 0.5 μ spherical) was used.

Example 4 In the liquid C (intermediate layer paint) prepared in Example 3, a further 0.1% was added.
A heat-sensitive recording material having a four-layer structure was produced in the same manner as in Example 3 except that 5 parts of 4μ spherical 50% styrene / butadiene plastic pigment aqueous dispersion (made by Nippon Zeon: 407BP) was added.

Example 5 In the C liquid (intermediate layer paint) prepared in Example 1, 0.55 μm was prepared as an acrylic / styrene plastic pigment.
Hollow sphere 42.5% acrylic / styrene plastic pigment (made by Rohm and Haas Japan: OP
-84J) was performed in the same manner as in Example 1 except that the same amount was used.
A heat-sensitive recording material having a layer structure was manufactured.

Comparative Example 1 Without adding the 45% acrylic / styrene plastic pigment aqueous dispersion to the C liquid (intermediate layer paint) used in Example 1, that is, 60 parts of 10% polyvinyl alcohol aqueous solution, 4 parts of 30% polyamide resin, A heat-sensitive recording material having a four-layer structure was obtained in the same manner as in Example 1 except that a liquid having a composition of 10 parts of 50% calcium carbonate aqueous dispersion and 30 parts of water was used.

Comparative Example 2 Instead of the C liquid (intermediate layer paint) used in Example 1, 10%
Polyvinyl alcohol aqueous solution (Gothenal T-350: manufactured by Nippon Gosei Co., Ltd.) 60 parts, 60% calcium carbonate (PC-700: manufactured by Shiraishi Industry) 10 parts aqueous dispersion, 45% acrylic / styrene plastic pigment (Rohm and Haas) A thermosensitive recording material having a four-layer structure was manufactured in the same manner as in Example 1 except that a liquid having a composition of 5 parts by weight (Japan-made: OP-42M: 0.55 μ spherical) and 30 parts by water was used.

Comparative Example 3 Instead of the C liquid (intermediate layer paint) used in Example 3, 10%
A four-layer constitution was carried out in the same manner as in Example 3 using a composition of 60 parts of polyurethane resin emulsion, 10 parts of 50% calcium carbonate aqueous dispersion, 5 parts of 0.5μ spherical 48% polystyrene plastic pigment, and 30 parts of water. Was prepared.

After leaving the heat-sensitive recording materials of the above-mentioned Examples and Comparative Examples at room temperature for 3 days, they were color-developed by solid black recording with TP-8300 (trade name, Toshiba Medical Thermal Printer), and Macbeth reflection densitometer (RD-514). A clear black color image was obtained at a high density of 1.5 or more. Then, a predetermined test piece was prepared from this by a conventional method, and the water resistance of the coloring part, the resistance to bifilm,
The gloss, oil resistance and sticking property were measured by the following tests. The results are shown in Table 1. As is clear from this table, in the heat-sensitive recording material of each example, water resistance,
It can be seen that it has excellent resistance to PVC film, oil resistance, and sticking properties, and its glossiness is 85% or more, which is similar to that of silver salt photographic paper. However, in each comparative example, an appropriate result is not obtained in some properties.

The measurement and evaluation of various properties shown in Table 1 were performed by the methods described below.

(1) Water resistance test: Specimens in water for 24 hours (at room temperature)
It is taken out after soaking, and evaluated by the elution state of the coating film and the residual concentration after drying.

(2) PVC film resistance test: A soft polyvinyl chloride film was overlaid on the test piece, and at each temperature of 20 ° C, 30
Evaluate from each residual concentration when both are contacted for 24 hours under the load of 0 g / cm ² .

(3) Oil resistance: Cottonseed oil is applied to the test piece by a conventional method,
Evaluate from each residual concentration after standing at 20 ℃ and 40 ℃ for 24 hours.

(4) Glossiness: Shows the glossiness when the incident angle = the light receiving angle = 75 °.

EFFECTS OF THE INVENTION The present invention makes it possible to provide excellent water resistance, plasticizer resistance, glossiness, oil resistance and the like by sequentially providing an intermediate layer and a gloss layer on a thermosensitive coloring layer in a thermosensitive recording material. The heat-sensitive recording material can be remarkably improved in storability and glossiness, and has stickability. As a result, the present invention can be used in a wider range of applications such as CRT medical printer paper, commuter pass, coupon ticket label paper and printer paper for various measuring instruments, which require full-scale long-term storability. It has the effect of enlarging.

Continuation of the front page (56) Reference JP-A-58-199189 (JP, A) JP-A-61-123582 (JP, A) JP-A-62-290579 (JP, A) JP-A-1-178486 (JP , A)

Claims (1)

[Claims] 1. A thermosensitive color-forming layer having a color-forming dye substance and a color-developing substance formed on the surface of a support, with an intermediate layer containing a water-soluble polymer substance, an inorganic pigment, a cross-linking agent and a plastic pigment interposed therebetween. A heat-sensitive recording material comprising a glossy layer containing a glossy hydrophobic polymer as a main component.