JPH0464485A - heat sensitive recording material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive recording material with excellent storage stability, and in particular to image recording paper, facsimile paper, train tickets,
The present invention relates to heat-sensitive recording materials that have improved storage properties such as moisture resistance, heat resistance, and plasticity (oil) resistance, and are used for commuter passes, labels for POS labels, prepaid cards, travel passes, and the like.

[Conventional technology]

Heat-sensitive recording materials are generally made of a color-developing substance such as an electron-donating dye, such as a leuco dye, and an organic acidic substance, such as an electron-accepting phenolic compound, on a support such as paper, synthetic paper, or plastic film. It is provided with a thermosensitive coloring layer whose main component is a chemical substance, and a recorded image can be obtained by reacting them with thermal energy. (For example, Special Publication No. 43-4160, Special Publication No. 45-14039
(Japanese Patent Publication No. 48-27736, etc.) Since the recording device is compact, inexpensive, and easy to maintain, heat-sensitive recording materials can be used for computer output,
Fax machines, automatic ticket vending machines, scientific measuring machine printers,
Alternatively, it is widely used in printers for CRT medical measuring instruments and the like.

However, conventional heat-sensitive recording materials in which only a heat-sensitive coloring layer containing a color-forming dye substance and a binder as active ingredients are coated on a support are resistant to light, water, temperature, plasticity, oil, etc. Due to its instability, changes over time during storage are always a problem. Therefore, when a desired print is made on such a heat-sensitive recording material, the recorded color develops very clearly, but the colored part may be in contact with water for a long time or be exposed to high temperatures (40°C).
-80 degrees Celsius) or high humidity for a long period of time, significant discoloration and background fogging usually occur.

These discolorations are particularly noticeable in color-forming type heat-sensitive recording materials that use dyes mainly composed of colorless or light-colored lactone compounds, that is, dye-coloring type heat-sensitive recording materials. Since this is a common problem that occurs, there has been a strong demand for its solution.

In order to improve such storage stability, it has been proposed to add a phenolic antioxidant to the heat-sensitive color forming layer or to provide a surface layer on the heat-sensitive color forming layer. For example, JP-A-5
9-167292, JP-A-59114096, JP-A-60-78782, and JP-A-59-93387, in which a phenolic antioxidant is blended into the heat-sensitive coloring layer; Or, JP-A-56-1467
96, in which a hydrophobic polymer compound emulsion is used as a protective layer, or JP-A-58
As seen in Publication No. 1.99189, a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer on a heat-sensitive coloring layer, and an oil-based paint containing a hydrophobic polymer compound as a resin component is applied thereon. One with a surface layer has been reported.

However, the combination of such phenolic antioxidants
In particular, it causes background stains (decreased whiteness) in the heat-sensitive coloring layer.
Density in non-image areas tends to increase during high temperature storage (60 degrees) (humidity resistance, heat resistance and plasticity resistance, iFl storage stability,
Not enough. In addition, in order to improve storage stability, it has been proposed to provide a water-soluble polymer compound overcoat layer on the heat-sensitive coloring layer, but storage under high temperature and high humidity is not perfect, and furthermore, Heat-sensitive recording materials manufactured by cutting, adhesive processing, etc. are applied to heat-sensitive recording materials coated with such an overcoat layer, because oil and other substances penetrate through the cut section and cause discoloration of the printed area. ,
Applying an overcoat layer cannot be called an essential solution.

(Problems to be Solved by the Invention) The present invention solves these problems and provides a heat-sensitive recording material with excellent long-term storage properties such as plasticizer resistance, moisture resistance, heat resistance, and oil resistance. The object of the present invention is to provide a heat-sensitive recording material that has significantly improved storage properties under severe conditions such as high temperatures.For example, when used as a heat-sensitive recording ticket for an automatic ticket vending machine, Of course, it can be used for coupon tickets, commuter passes, etc. that require shelf life,
PO8 barcode pricing is not only suitable for label paper that is attached to the packaging surface of fresh foods and oily meats packaged with polyvinyl chloride film, but also for long-term storage facsimile paper and CRT. It is an object of the present invention to provide a heat-sensitive recording material that can also be used as an image printer paper.

[Failure to solve the problem]

The present inventors have developed a heat-sensitive recording material that utilizes a color reaction between a colorless or light-colored electron-donating dye and a color developer consisting of an electron-accepting compound and has excellent storage properties. As a result of extensive research, we have completed the present invention.

The present invention relates to a heat-sensitive recording material comprising a heat-sensitive coloring layer provided on a support and comprising a colorless to light-colored electron-donating dye and a color developer consisting of an electron-accepting compound that reacts with the colorless to light-colored electron-donating dye and an electron-accepting compound that develops color. In the coloring layer, 2 [where M represents a metal selected from the group consisting of divalent to tetravalent metal ions, and n represents 2 to 4]
is characterized in that it contains at least one compound of acetylacetone metal salt having an integer of 4].

By incorporating an acetylacetone metal salt compound, which is a metal chelate compound, into the heat-sensitive coloring layer, image stability at high temperatures (40°C, 90% IIH), oil resistance, and plasticizer resistance is improved. In other words, it is possible to suppress fading of images and characters during storage.

Examples of preferable acetylacetone metal salt compounds include those having the following structure. Of course, it is not limited to this.

AZ(CsHJz)z, Cr(CsHtOz)3.
Co(CsH9Oz)z(HzO)z.

Co(Cs)l,Oz)+, Cu(CsH7oz)z
, Fe(CsHtOz)sNi(CsHJ□)Z(H
20)2. ν0(C9+4.0□)2Zn (C
sHl (h) (HJ), In (CsHl
Oz) 3+Ca(CsHvOz)z(HzO)z9M
g(Cs)lJz)z(HzO)z.

Mn(CsH7oz)z(HJ)z, Zr(Cs
HlOz)nSn(CsHlOz)z(H40Jz, T
i(OCJJz(CsHJz)z.

These compounds may be added in an amount of 1 to 10% of the total amount of the heat-sensitive coloring layer on a weight basis.
The content is preferably in the range of 3 to 7% by weight.

The color-forming dye used in the present invention is not particularly limited, and any dye used in general heat-sensitive recording paper, pressure-sensitive recording paper, etc. can be used.

Specific examples include (1) triarylmethane compounds, such as 3,3 bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal, high olent lactone), 3
-(p-dimethylaminophenyl 13-(C2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl) 1-(2-phenylindole-3)
-yl) ph9'J do, 3,3-bis-(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide,
3,3bis-(2-phenylindol-3-yl)5
-dimethylaminophthalide, etc.: (2) Diphenylmethane compounds, such as 4,4
Bis-dimethylaminobenzhydrin benzyl ether, N-halophenylleucoolamine, N2.4.5-
Trichlorophenylleukoolamine, etc.; (3) Xanthine compounds, such as rhodamine B-ayurinofuctam, 3-diethylamino-7-dihendylaminofluoran, 3-diethylamino-7-butylaminofluoran, 3-diethylamine-7- (2-chloroanilino)fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl 7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-anilino Fluoran, 3-cyclohexyl-methylamino-6-methyl 7-anilinofluorane, 3-diethylamino 6-chloro-7-(β-ethoxyethyl)aminofluorane, 3-diethylamino-
6-chloro7-(γ-chloropropyl)aminofluorane, 3-(N-ethyl-N-isoamyl)-6-methyl-7-phenylaminofluorane, 3-dibutylamino-6-methyl-7-ani Linofluorane, etc.: (4) Thiazine compounds, such as benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, etc.: (5) Spiro compounds, such as 3-methyl-spiro-
Examples include dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-hensylspiro-dinaphthopyran, and 3-methylnaphtho-(3-methoxyhenzo)-spiropyran. These may be used alone or as a mixture of two or more. The dye can be selected and used depending on the purpose and desired properties.

The color developer used in the present invention is composed of an electron-accepting organic acidic substance that can react with a color-forming dye under heating to cause it to develop color. Such a color developer liquefies or vaporizes at room temperature or higher, preferably 70° C. or higher, and reacts with the color-forming dye to develop color.

The color developer used in the present invention is, for example, 4,4'-isopropylidenediphenol [bisphenol A], 4.
4'-isopropylidene bis(2-chlorophenol)
, 4,4'-isopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2,6-t
ert-butylphenol), 4,4'-5ec-butylidene diphenol, 4,4'-cyclohexylidene diphenol, 4tart 7' tylphenol, 4
-Phenylphenol, 4-hydroxydiphenoxide, naphthol, β-naphthol, methyl-4-hydroxyhenzoate, 4-hydroxy-acetophenone, salicylic acid anilide, novolac-type phenolic resin, halogenated novolac-type phenolic resin, 44'-thiobis( 3-methyl-5-tert-butylphenol), P
- Proyl hydroxybenzoate, isopropyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, methylbenzyl p-hydroxybenzoate, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, stearin Aliphatic carboxylic acids such as 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-dioxahebutane, p-nitrobenzoic acid, these organic color developers and polyesters such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, etc. Salts with valent metals, 4,4'-dihydroxydiphenylsulfone, 2
．． 4'-dihydroxydiphenylsulfone, 3.4'-
Dihydroxydiphenylsulfone, 3,3'-diamino-4,4'-dihydroxy-diphenylsulfone, 33
'-diallyl 4,4'-dihydroxy-diphenyl sulfone, 3,3'dichloro-4,4'-dihydroxy diphenyl sulfone, 4-hydroxy-diphenyl sulfone, 4-hydroxy-4'-isopropyldiphenyl sulfone, 4-hydroxy-4 '-isopropyloxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 2,4-dihydroxy-diphenylsulfone, 24-dihydroxy-4'methyldiphenylsulfone, 3,4-dihydroxydiphenyl-P-)
It is made up of at least one member selected from risulfone and the like. This color developer is usually mixed and used in a ratio of 1 to 5 parts by weight, preferably 1.5 to 3 parts by weight, per 1 part by weight of the color-forming dye.

In order to form a thermosensitive coloring layer on the support, any known coating method such as air knife, blade, gravure, roll coater, spray, dipping, bar, extrusion, etc. can be used.

As the support, papers such as high-quality paper, medium-quality paper, art paper, cast-coated paper, paperboard, and tissue paper are used, and in addition, plastic film, synthetic paper, laminated paper, aluminum foil, etc. can also be used.

All known binders can be used as the binder for the thermosensitive coloring layer. However, it is preferable that the liquid does not develop color, aggregate, or become highly viscous when mixed with each dispersion of the color-forming dye and the color-developing substance, and it is preferable that the liquid does not develop color, aggregate, or become highly viscous. It is required that the film formed on the sheet be strong and have no sterilizing effect.

Typical aqueous binders include polyvinyl alcohol, modified starch, gum arabic, gelatin, methylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, polyvinylpyrrolidone, diisobutylene-maleic anhydride copolymer, carboxymethylcellulose, acrylic acid amide-acrylic ester acid. Copolymer, isibutylene-maleic anhydride copolymer, alginate, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer, acrylic acid Emulsions of ester, polyacrylate, polyacrylamide, ethylene-acrylic acid copolymer, polyurethane, polyvinyl acetate, styrene-butadiene latex, etc. can be used. In order to impart water resistance to the coating film, a combination of a water-soluble polymer compound containing a reactive group, such as an acetoacetyl group or an amide group, and a crosslinking agent is preferred.

Examples of crosslinking agents include dialdehydes such as glyoxal and polyaldehyde, polyamines such as polyethylene amine, epoxy systems, polyamide resins, diglycidyl systems such as glycerin diglycidyl ether, ammonium persulfates such as dimethylol urea, ferric chloride, and ammonium chloride. , magnesium chloride, and other known compounds are used.

Examples of pigments include calcium carbonate, magnesium carbonate, kaolin, clay, talc, fired clay, warp,
In addition to inorganic fine powders such as diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, and surface-treated calcium carbonate and silica,
Examples include organic fine powders such as urea-formalin resin powder, styrene-methacrylic acid copolymer powder, polystyrene resin powder, styrene powder, nylon powder, polyethylene powder, epoxy resin powder, henzoguanamine resin powder, and raw starch particles. be able to.

In addition, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances (or lubricants), etc., may be added to the heat-sensitive coloring layer, if necessary. There is no problem. Thermofusible substances include, for example, stearamide, stearate ethylene bisamide,
Fatty acid amides such as moncilic acid amide, oleic acid amide, palmitylic acid amide, coconut fatty acid amide, and hehenic acid amide, waxes such as zinc stearate, calcium stearate, montanic acid wax, polyethylene wax, carnauba wax, paraffin wax, and ester wax. , terephthalic acid dimethyl ester, terephthalic acid dibutyl ester, terephthalic acid dihenzyl ester, isophthalic acid dibutyl ester, 1-hydroxynaphthoic acid phenyl ester, 1,2-di(3-methylphenoxy)ethane, 12-diphenoxyethane, 1 -phenoxy-2-(4-methylphenoxy)ethane, diphenyl carbonate, p-benzylbiphenyl, 212-methylenebis(4-methyl-6-t-butylphenol), 4.
4-butylidenebis(6-t-butyl-3-methylphenol), 1,1,3-tris-(2-methyl4-hydroxy-5-t-butylphenyl)butane, 2,2-
Methylenebis(4-ethyl-6-1-butylphenol), 2,4-di-t-butyl-3-methylphenol,
4. Hindered phenols such as 4-thiobis (3-methyl-6-butylphenol), 2-(2'-hydroxy-5'-methylphenyl)hencytriazole, dihenzyl terephthalate, 1-hydroxy-2- Phenyl naphthoate, dihenzyl oxalate, adipic acid -〇-
Chlorhensyl, di-p-chlorhensyl oxalate, 2
Examples include various thermofusible substances such as sensitizers such as -hydroxy-4-hensyloxyhensiphenone, lubricants, antioxidants, and ultraviolet inhibitors. The amount of the thermofusible substance added is generally preferably 4 parts by weight or less per 1 part by weight of the color developer. For dispersing dyes, color developers, sensitizers, and other additives, a pulverizer such as a ball mill, attritor, or sand grinder dyno mill is used.

Further, if necessary, it is also possible to provide an undercoat layer under the heat-sensitive color forming layer, a protective layer on the heat-sensitive color forming layer, or a conductive layer on the back surface of the heat-sensitive recording material.

〔Example〕

The present invention will be explained in more detail below with reference to Examples, but the scope of the present invention is of course not limited thereto.

In each example, "1 part" indicates "part by weight."

Example 1 The following solutions were prepared with the following compositions.

(1) Preparation of liquid A (dye for thermosensitive coloring layer) 3-(N-ethyl-N-chlorohequine J diamino)-6
-Methyl-77nylinofluorane
60 parts 8χ Human σ xieton Lucertos water m solution 15 m water 60 parts (2) Preparation of solution B (color developer for heat-sensitive coloring layer) 2.4-Shihi F
Loquin Diphenylsulhon
100 parts 8XfuLf xylmethylseltos aqueous solution
25 parts water
125 parts (3) Preparation of C lacquer (storage stabilizer) Acetylacetone zinc lOx I lipinyl alcohol aqueous solution water The above solutions A, B and C were dispersed and ground to an average particle size of 1 with a sand grinder.

55 parts 25 parts 58 parts Each separately until below μ (4) Formation of thermosensitive coloring layer Solution A 50 parts Solution B
100 parts C liquid
20 parts 60% calcium carbonate aqueous dispersion
67 parts 20% zinc stearate aqueous dispersion e, 35 parts 10 parts polyvinyl alcohol aqueous solution 240 parts water
130 parts of this coating liquid was coated at 50 g/n (on the surface of a support made of high-quality paper so that the dry weight was 1 g/rd, and after drying,
Bek smoothness is 100 after super calendering
A thermosensitive coloring layer was formed for 0 seconds.

Example 2 The same components as in Example 1 were used except that the same amount of nickel acetylacetone was used instead of zinc acetylacetone in the C solution used in Example 1, and the same treatment was performed to achieve a Bekk smoothness of 120 seconds. A heat-sensitive recording material was obtained.

Example 3 10% polyvinyl alcohol aqueous solution (Kuraray PVA-117) was applied on the thermosensitive coloring layer formed based on Example 1.
0 parts by weight, 60% clay aqueous dispersion (Hyuber Co., Ltd.: Hyde Mouth Gloss-90) 15 parts by weight, 10 parts Organic boron compound (Toho Chemical, Emalbon GB) 6 parts by weight and 48 parts by weight of water as active ingredients. A heat-sensitive recording material having an edge smoothness of 1500 seconds was obtained.

Example 4 In preparing C lacquer used in Example 1, 4,4'-thiobis=(3-methyl-6tert-
55 parts of (butylphenol) were further added.

Other than this, Bekk smoothness was 1000 in the same manner as in Example 1.
A second heat-sensitive recording material was obtained.

Comparative Example 1 A heat-sensitive recording material was obtained by using the same components as in Example 1, except that the liquid C of Example 1 was not blended, and by carrying out the same treatment.

Comparative Example 2 In Solution C of Example 1, the same amount of 2,2'-methyl-bis-(4methyl-5
A heat-sensitive recording material was obtained in the same manner as in Example 1 using the same components except that tert-butylphenol) was used.

After each of the heat-sensitive recording materials obtained in the above Examples and Comparative Examples was left at room temperature for 3 days, color was developed using a black record using TP-8300) 1 (manufactured by Toshiba Medical). 514), a clear black colored image with a high density of 1.2 or higher was obtained. Next, a predetermined test piece was prepared from this material by a conventional method, and the heat resistance, moisture resistance, oil resistance, and plasticizer resistance of the colored part were measured by the following test method.

(1) Moisture resistance test: The test piece was left in a thermostatic chamber at 40° C. and 90% RH for 24 hours, and then the color density was measured using a Machess densitometer.

(2) Heat resistance test: Place the specimen in a constant temperature room at 50°C for 24 hours.
After standing for a period of time, the color density was measured using a Macbeth density needle.

(3) PVC film resistance test = (Plasticizer resistance test) A soft polyvinyl chloride film is superimposed on the specimen, and
The evaluation is based on each residual concentration when the two are brought into contact for 24 hours under a load of 300 g/ai at a temperature of °C.

(4) Oil resistance test: Apply cottonseed oil to the specimen using the usual method and heat at 20°C and 140°.
Evaluation is made based on each residual concentration after being left at each temperature of C for 24 hours.

The results are shown in Table 1. As is clear from this table, each example has heat resistance, moisture resistance, oil resistance,
Satisfactory results were obtained in all plasticizer resistance tests. However, in the comparative examples, heat resistance, moisture resistance,
Regarding the oil resistance and plasticizer resistance tests, no product showed satisfactory results in all of them.

[Effect of the invention] The present invention has excellent moisture resistance and heat resistance, and
In particular, it provides a heat-sensitive recording material with excellent oil resistance and plasticizer resistance, making it possible to create a heat-sensitive recording material with significantly improved shelf life, especially when stored under harsh conditions such as high temperature and high humidity. It is something to do.

(1 other person)

Claims (1)

[Scope of Claims] A heat-sensitive recording in which a heat-sensitive coloring layer is provided on a support, which utilizes a coloring reaction between a colorless or light-colored electron-donating dye and an electron-accepting compound that can be colored by contacting it with heat. In the material, the thermosensitive coloring layer has a formula ▲ mathematical formula, chemical formula, table, etc. ▼ (I) [In the formula, M represents one type of metal selected from the group consisting of divalent to tetravalent metal ions, and n represents an integer from 2 to 4. ] A heat-sensitive recording material characterized by containing at least one compound selected from acetylacetone metal salt compounds having the following.