JPS5825987A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a heat sensitive recording material excellent in the head matching property free from color development due to pressing by arranging a coat layer containing a color eliminator on the surface thereof. CONSTITUTION:A coat layer containing 5-100wt%, preferably 20-50wt% eliminator is arranged on the surface of a heat sensitive color developing layer comprising a leuco dye, an acid substance, a binder and the like at a coating rate of 0.1-5g/m<2> at the dry period. The color eliminator herein used include an alkylene oxide adduct of bisphenols, methylol amide and bisamide with a melting point of more than 110 deg.C, long chain 1, 2-glycol. This prevents weak color development otherwise caused by a calender and rubbing with a finger or the like. In addition to the color eliminator, the coat layer may contain water- soluble high polymer such as polyvinyl alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, more specifically, a heat-sensitive coloring layer containing as a main component a usually colorless or light-colored leuco dye and an acidic substance capable of coloring the leuco dye when heated, on a support. The present invention relates to an improvement in a heat-sensitive recording material having a structure formed in the following manner.

Thermosensitive recording materials are recording materials that have a structure in which a so-called thermosensitive coloring layer that develops color when heated is formed on a support such as paper, synthetic paper, or resin film. etc. are used. In addition to being used for copying books, documents, etc., such recording materials are widely used in fields such as output records of electronic computers, facsimile machines, computers, etc., and labels.

In addition to heating, such heat-sensitive recording materials develop color when pressure is applied, for example, when calendering is performed during the production of the heat-sensitive recording material, or when the material is scratched or rubbed. It has the disadvantage of pressure color development),
This often causes serious problems in practical use. Also, when heating a thermosensitive recording notebook to record, the components in the thermosensitive coloring layer may melt and stick to the thermal head or thermal pen (resistance adhering), causing inconvenience in feeding the paper or causing a sticking phenomenon. , the sticky substance may be transferred to the recording sheet and cause trailing. These characteristics are called head matching, and are extremely important when considering the quality of heat-sensitive recording sheets.

As a result of repeated research in order to solve the above-mentioned problems, the present inventors have found that by providing a coating layer containing a decoloring agent on the surface of the heat-sensitive coloring layer, excellent sheeting and head matching properties and pressure-sensitive The present invention was completed by discovering that a heat-sensitive recording material without color development can be obtained.

That is, according to the present invention, in a heat-sensitive recording material having a structure in which a heat-sensitive color forming layer containing a leuco dye and an acidic substance that reacts with the leuco dye to form a color by heating is provided on a support, the heat-sensitive recording material contains a decoloring agent. A heat-sensitive recording material is provided, characterized in that a coating layer is provided on the surface of the heat-sensitive coloring layer.

In the present invention, the "decolorizing agent" refers to color development by a calender,
It refers to something that has the effect of preventing weak color development, such as pressure color development when pressing with a finger.Specifically, the following can be cited.

a) Alkylene oxide adduct of bisphenols -H where A is methylene or alkylidene, m and 1-1
An integer of 0.

b) Methylolamides and bisamides with a melting point of 110 C or more (Japanese Patent Application No. 80577/1983) C) Long chains 1.2-
Glycol (Japanese Patent Application No. 1983-99563) d) Ethylene oxide adduct of terephthalic acid (Patent Application No. 1987-99563)
96666) e) Solid alcohols such as stearyl alcohol, tripropylcarpinonyl, polyethylene glycol, polypropylene glycol, I,8-octanediol, dimethylpentaglycerin, L,2,3,4-tetraoxybutane (Japanese Patent Publication No. 1983- 17865) ``)Polymer of polyoxydecamethylene, polyoxymethylene, polyethylene oxide, trimethylene oxide,
Polyethers or polynibs such as l,3-dioxolane polymers, polyoxyethylene alkylamine, nrubitan monostearate, polyoxyethylene oleyl ether, polyethylene glycol monostearate, polyoxyethylene alkylamide, oxyethylene alkylamine, etc. Rangelicol derivatives (Special Publication 1970-
17867 and Special Publication No. 17868) g)
Aceto, amide, stearamide, phthalonitrile, m
-Nitroaniline, β-naphthylamine (Special Publication 1977-
19991) h) 1.3-') Cyclohexyl-2-phenylguanidine, 1,3-dicyclohexyl-2-naphthylguanidine, 2,3-cyfchlorohexyl-1-phenylguanidine, 1,2.3- ) Guanidine derivatives such as IJ phenylguanidine (Special Publication No. 1989-
29024) 1) Hexadecylamine, tribenzylamine, N, N
, N',N'-tetrabenzylethylenediamine, dolycyclohexylamine, dioctadecylamine, 2-
Amine or quaternary ammonium salt such as aminobenzoxazole, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride (Japanese Unexamined Patent Publication No. 18048/1983) In the present invention, the coating layer provided on the heat-sensitive coloring layer is , a water-soluble polymer may be included together with the above-mentioned decolorizing agent, and examples of the water-soluble polymer in this case include the following.

Polyvinyl alcohol, Calhokit methyl cellulose,
Starch, methylcellulose, styrene maleic anhydride copolymer, acrylic ester emulsion, etc.

The content of the decolorizing agent in the coating layer is preferably 5 to 100%, particularly 20 to 5%, based on the weight of the entire coating layer.
A range of 0% is effective. The coating amount of the coating layer is preferably 0.1 to 5 g/mj, particularly preferably 0.5 to 2 g/m, on a dry basis. 0.1g/7
7 (If the amount is less than 5 g/m, the desired effect of preventing pressure color development will decrease, and if it exceeds 5 g/m, the color image density will decrease. Various additives can be included as long as they do not impair the purpose.

Next, specific examples will be shown regarding the leuco dye, acidic substance, and binder as components for forming the heat-sensitive coloring layer of the present invention.

(4) Leuco dye As the leuco dye, leuco forms of the various colorless or light-colored dyes shown below are usually used.

(a) Leuco compound of triphenylmethane dye represented by the following general formula: Rz (wherein Rx, Ry and R2 are hydrogen or hydroxyl group)
・Rogen, alkyl group, nitro group, amine group, dialkylamino group, monoalkyl group, allyl group. ) Specific examples of the above leuco compounds are as follows.

3.3-bis(p-dimethylaminophenyl)-phthalide 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone) 3.3-bis(p-dimethylaminophenyl) )-6-diethylaminophthalide 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide 3.3-bis(p-dibutylaminophenyl)phthalide (b) Leuco fluoran dye represented by the following general formula Compound: Z In the formula, RX , Ry and Rz are the same as in (a) above. Specific examples of the above compound are as follows.

3-Cyclohexylamino-6-chlorofluorane 3-(N,,N-diethylamino)-5-methyl-7-
(N,N-dibenzylamino)fluoran 3-dimethylamino-5,7-dimethylfluoran 3-dimethylamino-7-methylfluoran 3-diethylamino-7,8-benzfluoran 0 Leuco fluoran dye Compound: 3-diethylamino-6-methyl-7-chlorofluoran 3-pyrrolidino-6-methyl-7-anilinofluoran 2-(N-(3'-)chloroomethylphenyl)amine)-6-diethylamino Fluorane 2-(3,6-bis(diethylamino)-9-(0-
chloranilino)xanthylbenzoic acid lactam) lactone compound represented by the following general formula: 3 R4 where R1 and R2 are hydrogen, a lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted phenyl group, It represents a cyanethyl group, a β-halogenated ethyl group, or R1 and R2 are bonded together and CH2,
, moCH2su, or soCH2arrow 20moCH2chi2, R3 and R4 represent hydrogen, a lower alkyl group, an alkyl group, an amino group or a phenyl group, and R3 and R4
Any one of is hydrogen, X, and X2 and X3
represents hydrogen, lower alkyl group, lower alkoxyl group, halogen atom, halogenated methyl group, nitro group, amine group, or substituted amine group, X4 represents hydrogen, halogen, lower alkyl group or lower alkokynol group,
n represents 0 or an integer of 1-4.

Specific examples of the above compounds are as follows.

3- (2'-hydroxy-4'-dimethylaminophenyl) -3-(2'-methoxy-5'-chlorophenyl) phthalide 3- (2'-hydroxy-4'-dimethylaminophenyl) -3-( 2'-Methoxy-5'-nitrophenyl)phthalide 3- (2'-hydroxy-4'-diethylaminophenyl) -3-(2'-methoxy-5-methylphenyl)phthalide 3- (2'-methoxy- 4'-dimethylaminophenyl) -3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide.

(g)) Acidic Substances The following various acidic substances can be used as the acidic substances that react with the above-mentioned leuco dye to develop color when heated.

(a) Organic and inorganic acids boric acid, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, benzoic acid, stearic acid, gallic acid, salicylic acid, l-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-
p-) Ruylic acid.

(b) Phenolic substances 3.5-xylenol, thymol, p-+erl-butylphenol, 4-hydroxyphenoxyto, methyl-
4-hydroxybesozoeshimado, -hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resolmethylenebis(4-methyl-61erj-butylphenol), 2,2-bis(4-hydroxyphenyl) Propane, 4,4-impropylidene-bis(2
-tert-butylphenol), 4.4-see
-phteridene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid.

(0) Binder As the binder for bonding and supporting the thermosensitive coloring layer on the support, various binders as shown below can be used.

water-soluble ones such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, etc.
Blue can be made of polystyrene, vinyl chloride-vinyl acetate copolymer.

In addition, if necessary, conventional auxiliary additives such as fine powders such as calcium carbonate, silica, alumina, magnesia, talc, titania, barium sulfate, and aluminum stearate may be added to the heat-sensitive coloring layer to develop color. Image clarity can be improved. In addition, a heat sensitivity increasing agent such as a rubber, a higher fatty acid amide, etc. can be included.

In order to obtain the heat-sensitive recording material of the present invention, it is necessary to add other commonly known additives alone or in combination with each other except for the color-forming substance into an aqueous medium together with a protective colloid such as polyvinyl alcohol, a surfactant, etc. In addition, it is pulverized and dispersed using a dispersing machine such as a ball mill, attritor, or sand mill. Next, the respective dispersions are mixed to prepare a heat-sensitive coloring layer coating solution, which is coated on a support such as paper, synthetic paper, or plastic film, and dried to form a heat-sensitive coloring layer.

Next, a coating liquid containing a decolorizing agent, a water-soluble polymer, etc. is prepared,
This is applied onto the heat-sensitive coloring layer and dried to form a coating layer.

The present invention can also be effectively applied to paper for weighing labels, coupon tickets, train tickets, and the like. When used as a label, an adhesive layer and a release mount may be laminated on the back side of the support, and when used as a ticket, a magnetic recording layer containing a ferromagnetic material as a main component is provided on the back side of the support.

Next, the present invention will be explained in more detail with reference to Examples.

Example Dispersion A having the following component composition was prepared using a ball mill.

B and C were prepared.

[Dispersion A]

3-cyclohexylamino-6-mether-7- 60 parts by weight Anilinofluoran hydroxyethyl cellulose (10% aqueous solution) 6 o Water 1
8o [Dispersion B] Bisphenol A 60 parts by weight Hydroxyethyl cellulose (5% aqueous solution) 6o Water
18
o [Dispersion C] Calcium carbonate 60 parts by weight Methyl cellulose (5% aqueous solution) 120 u
water 120
Parts by weight Next, 1 part by weight of dispersion A, 3 parts by weight of dispersion B, and 2 parts by weight of dispersion C were mixed to prepare a thermosensitive coloring layer forming liquid, and this was mixed with a standard basis weight of 60 g/ The mixture was coated on a commercially available high-quality paper with a dry coating weight of 6 g/m, and dried to form a heat-sensitive coloring layer. After drying, a coating layer forming dispersion liquid consisting of the following components was coated on the heat-sensitive coloring layer so that the dry coating amount was 1 to 2 g/m' and dried to obtain a heat-sensitive recording paper.

[Dispersion D]

OH330 parts by weight Methyl cellulose (5% aqueous solution) 60
tt water
2. 7゜The recording paper obtained as above was calendered to a smoothness of about 300 seconds, and the background density before calendering was 0.05, but after calendering it was 0. It changed to .07. Further, when black solid printing was performed on the recording paper after calendering using a thermal facsimile (0KIFAX7100), the color image density was 1.19. At this time, no occurrence of sticking or trailing was observed. Furthermore, when the recording paper was rubbed with a fingernail, no pressure coloring was observed. Note that the background density and color image density were measured using a Macbeth densitometer.

Comparative Example A quality test was conducted in the same manner as in the above example for the recording paper in which the dispersion liquid was not applied on the thermosensitive coloring layer in the above example, and it was found that the background density before calendering was 0.05, and the background density after calendering was 0.05. was 0.15, and the color image density of the print was 1.20, and no sticking or trailing was observed, but when rubbed with a fingernail, strong pressure coloring was observed.

Claims (1)

[Claims] (1) In a heat-sensitive recording material having a structure in which a heat-sensitive coloring layer containing a leuco dye and an acidic substance that reacts with the leuco dye to form a color by heating is provided on a support, a coating layer containing a decolorizing agent is attached to the heat-sensitive coloring layer. A heat-sensitive recording material characterized by having a coloring layer provided on the surface.