JPH0462185A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To prevent static electricity of a heat sensitive sheet at the time of a facsimile communication and to improve stackability by providing a back coating layer containing no conductive titanium oxide on the surface coated with no heat sensitive coloring layer of a support or incorporating the titanium oxide in the coloring layer. CONSTITUTION:This heat sensitive recording material is provided with a heat sensitive coloring layer containing colorless or pale electron donative dye precursor and electron acceptive substance for coloring in reaction with the precursor as main ingredients on a support. A back coating layer containing conductive titanium oxide is provided on the surface coated with no coloring layer of the support, or the titanium oxide is contained in the coloring layer. In order to improve coloring sensitivity, to prevent adherence of a thermal head, etc., to a thermal element, it is desirable to provide one or more intermediate layers between the support and the coloring layer. The titanium oxide is used to improve from characteristic of high conductivity to a defect due to static electricity of a heat sensitive recording material to be generated at the time of a facsimile communication.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a heat-sensitive recording material.

(Prior Art) Conventional general heat-sensitive recording materials consist of a colorless or light-colored electron-donating dye precursor (hereinafter abbreviated as "colorless dye") and an electron-accepting compound ( A two-component coloring system consisting of a color developer (hereinafter abbreviated as a "color developer") is further provided with a heat-sensitive coloring layer in which a binder, a sensitivity improver, a lubricant, a filler, and other auxiliaries are dispersed. Kosho 43-41
No. 60, Japanese Patent Publication No. 45-14039, etc.

This type of two-component color-forming heat-sensitive recording material allows a color image to be easily obtained by heating with a heating element (thermal head, thermal pen, etc.), and has the following characteristics.

(1) - Secondary color development, no need for development or fixing.

(2) There is no need to replenish toner, etc., and maintenance of the recording machine is easy.

(3) The paper quality is similar to ordinary paper, so there is no discomfort.

(4) High color density and clear images can be obtained.

(5) By changing the type of colorless dye, different color tones can be easily obtained.

Due to these advantages, two-component heat-sensitive recording materials are most commonly used among heat-sensitive recording materials, and their use in fields such as facsimiles, printers, measurement records, and labels has increased significantly in recent years.

(Problems to be Solved by the Invention) However, with conventional thermal paper, static electricity generated on the thermal paper during facsimile communication causes problems such as the thermal paper clinging to the facsimile body during communication, and the receiver falling off the shelf. However, it had the disadvantage of poor stackability.

[Means and Actions for Solving the Problems] Accordingly, an object of the present invention is to provide a thermal recording material which prevents static electricity on thermal paper during facsimile communication and improves stackability.

The heat-sensitive recording material that achieves the object of the present invention is characterized by having a heat-sensitive color-forming layer on a support containing a colorless dye and a color developer that reacts with the colorless dye as main components to form a color. In this method, a back coat layer containing conductive titanium oxide is provided on the surface of the support not coated with the heat-sensitive coloring layer, or conductive titanium oxide is contained in the heat-sensitive coloring layer.

It is preferable that the heat-sensitive recording material is provided with an intermediate layer on the support between the support and the heat-sensitive coloring layer in order to improve color development sensitivity and prevent dregs from adhering to a thermal element such as a thermal head. Further, in order to improve storage stability, one or more overcoat layers may be provided on the heat-sensitive coloring layer.

In a heat-sensitive recording material, the back coat layer, which is provided on the side of the support that is not coated with the heat-sensitive coloring layer, is prepared by adding conductive titanium oxide to a binder to prepare a slurry-like coating liquid, and applying this to the support. It can be formed by coating and drying the surface.

Examples of the binder include polyvinyl alcohol, starch, methylcellulose, styrene/butadiene copolymer, etc., but the binder is not limited to these, and they may be used in combination.

The reason why the heat-sensitive recording material of the present invention exhibits a remarkable stackability improvement effect is considered to be as follows.

That is, by using conductive titanium oxide, it is thought that problems caused by static electricity in heat-sensitive recording materials that occur during facsimile communication can be improved due to its particularly high conductivity.

The conductive titanium oxide in the present invention refers to a conductive material based on titanium oxide, whose surface is treated with a tin oxide-based conductive layer. 6001, Tybake ET-1000111, etc., but are not particularly limited to these.

The content of conductive titanium oxide in the back coat layer or the heat-sensitive coloring layer is preferably 0.01 to 2.0 g/m2, more preferably 0.3 to 1.2 g/m2.

The colorless dyes and color developers used in the present invention are not particularly limited as long as they are used in general pressure-sensitive recording materials, heat-sensitive recording materials, etc. Colorless dyes include triarylmethane compounds, diphenylmethane compounds, Examples include xanthine compounds, thiazine compounds, and spiropyran compounds. Specific examples of colorless dyes are shown below, but the invention is not limited thereto.

Some examples of colorless dyes include triarylmethane compounds such as 3.3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone), 3.3-bis( p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-
There are 3-(2-methylindol-3-yl) phthalide, etc., and diphenylmethane compounds include 4゜4'
-bis~dimethylaminobenzhydrin befuryl ether, N-herophenyl leukoolamine, N-2,4
, 5-1-lichlorophenyl leukoolamine, etc., and xanthine compounds include rhodamine-B-anisonolactam, rhodamine (p-nitrino)lactam,
-(dibenzylamino)fluoran, 2-phenylamino-6-dinithylaminofluoran, 2-(o-chloroanilino)-6-dinithylaminofluoran, 2-(
3,4dichloroanilino)-6-dinithylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-phenyl-6-dinithylaminofluorane, 2-anilino-3- Methyl-6-dimethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-
N-ethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-(isopropyl)aminofluorane, 2-anilino-3-methyl-6-N-methyl-
N-pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-dinithylaminofluorane, 2-anilino-3- Chloro-6-dimethylaminofluorane, 2-anilino-3-methyl-6-
N-ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-isoamylaminofluorane, 2-anilino-3-chloro-6-dinithylaminofluorane, 2- Anilino-3-chloro-
6-N-methyl-N-dithylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-anilino-3-chloro-
8-N-methyl-N-pentylaminofluorane, 2-
Anilino-3-chloro-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-
6-N-ethyl-N-pentylaminofluorane, 2-
Anilino-3-chloro-6-N-ethyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-
Methyl-6-dimethylaminofluorane, 2-(p-methylanilino)-3-methyl-6-dinithylaminofluorane, 2-(p-methylanilino)-3-methyl-6
-N-methyl-N-dithylaminofluorane, 2-(p
-methylanilino)-3-methyl-6-N-methyl-N
-(isopropyl)aminofluorane, 2-(p-methylanilino)3-methyl-6-N-methyl-N-pentylaminofluorane, 2-(p-methylanilino)-3
-Methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-(p-methylanilino)-3-methyl-6-N-ethyl-N-pentylaminofluorane, 2
-(p-methylanilino)-3-chloro-6-dimethylaminofluorane, 2-(p-methylanilino)-3-
Chloro-6-dinithylaminofluorane, 2-(p-methylanilino)-3-chloro-6-N-methyl-N-ethylaminofluorane, 2-(p-methylanilino)-
3-Chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-(ρ-methylanilino)-3-chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-(p-methylanilino)-3-chloro-6-N-methyl-N-(isopropyl)aminofluorane -methylanilino)-3-chloro-
6-N-methyl-N-cyclohexylaminofluorane, 2-(p-methylanilino)-3-chloro-6-N-
Methyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-chloro-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3-methyl-
6-N-methyl-N-furylmethylaminofluorane,
There are 2-anilino-3-ethyl-6-N-methyl-N-furylmethylaminofluorane, etc., thiazine compounds include benzoloucomethylene blue and p-nitrobenzylleucomethylene blue, and spiropyran compounds include: 3-ethyl-spiro-
dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3.3'-dichlorospiro-dinaphthopyran, 3
-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, 3-
Examples include propyl-spiro-dibenzobilane.

The content of colorless dye in the heat-sensitive recording layer is 0.2 to 1
．． 0 g/m' is preferred.

As a color developer for coloring a colorless dye, an organic acidic substance that is solid at room temperature and heat-melting can be used, such as phenolic compounds, aromatic carboxylic acid compounds, novolac type phenolic resins, etc. . Typical examples thereof include bisphenol conductors, hydroxybenzoic acid esters, and salicylic acid esters. Additionally, inorganic acids such as clay, activated clay, activated silica, boric acid, and zinc oxide can also be used. The content of this color developer in the heat-sensitive recording layer is preferably 0.2 to 4.0 g/ba.

Among these color developers, phenolic compounds and aromatic carboxylic acid compounds are particularly preferred, examples of which are 2.2.
-bis(4'-hydroxyphenyl)propane, 2.2
-bis(4”-hydroxyphenyl)pentane, 2.2
-bis(4′-hydroxy-3°,′5°-dichlorophenyl)propane, 1,1-bis(4°-hydroxyphenyl)cyclohexane, 2,2-bis(4°-hydroxyphenyl)hexane, 11-bis (4'-hydroxyphenyl)propane, 1,1-bis(4'-hydroxyphenyl)butane, 1,1-bis(4'-hydroxyphenyl)pentane, 1,1-bis(4'-hydroxyphenyl)hexane , 1,1-bis(4'-hydroxyphenyl)hebutane, 1,1-bis(4'-hydroxyphenyl)-2-methyl-pentane, 1,1-bis(4
“-Hydroxyphenyl)-2-ethyl-hexane, 1
．． 1-bis(4°-hydroxyphenyl)dodecane, 3
゜3-bis(4°-hydroxyphenyl)pentane, 1
．． 2-bis(4′-hydroxyphenyl)ethane, 1.
1-bis(4″-hydroxyphenyl)sulfite, 1
．． 1-bis(3′-allyl-4°-hydroxyphenyl)sulfone, 1.1-bis(4″-hydroxyphenyl)sulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, 1.1-bis(4 °-hydroxyphenyl) ether, 2,2-bis(4°-hydroxy-3゛5°-dichlorophninyl)butane, 2,4-dihydroxybenzoic acid phenyl, 2゜4-dihydrois 4
-Phenyl methyl-benzoate, phenyl 2,4-dihydroxy-4°-chlorobenzoate, phenyl 2,4-dihydroxy-6-methylbenzoate, phenyl 2,4,6-drihydroxybenzoate, 2.4- dihydroxy-6
, 4゛-dimethylbenzoic acid phenyl, 2゜4-dihydroxy-6-methyl-4゛-chlorobenzoic acid phenyl, 2
．． Benzyl 4-dihydroxybenzoate, benzyl 2.4-dihydroxy-4'-methylbenzoate, benzyl 2.4-dihydroxy-4'-chlorobenzoate, benzyl 2.4-dihydroxy-6-methylbenzoate, 24. 6-
Pencil dolihydroxybenzoate, benzyl 2,4-dihydroxy6.4''-dimethylbenzoate, benzyl 2,4-dihydroxy-6-methyl-4°-chlorobenzoate, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoate Acid propyl ester, 4-hydroxybenzoic acid isopropyl ester, 4-hydroxybenzoic acid benzyl ester, 4-hydroxy-4''-chlorobenzoic acid benzyl ester, 4-hydroxy-4°-methylbenzoic acid benzyl ester, 4-hydroxy- Examples include compounds such as benzyl 4'-ethylbenzoic acid ester, but are not particularly limited to these.

Note that the sensitizer (
A color development sensitivity improver) may also be used. Some examples of sensitizers include waxes such as stearamide, methylene bisamide stearate, oleic acid amide, valmitic acid amide, and coconut fatty acid amide, nitrogen-containing compounds, carboxylic acid esters, naphthol derivatives, and naphthoic discourse conductors. , benzoic acid ester derivatives, etc., but the present invention is not limited to these, and these may be used in combination, or various known compounds may also be used in combination.

The content of this sensitizer in the heat-sensitive recording material is 0.2 to 4.0
Preferably, fillers are used in the present invention. These fillers include calcium carbonate, clay, calcined clay silica,
Inorganic white pigments such as zinc oxide, titanium oxide, talc, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, barium sulfate, and surface-treated silica, as well as organic fine particles such as starch, polystyrene resin, urea-formalin resin, etc. can be mentioned.

Binding agents for binding colorless dyes, color developers, white organic pigments, etc. on the support include polyvinyl alcohol and its conductors, polyvinylpyrrolidone, starch and its derivatives, hydroxyethylcellulose, ethylcellulose, methylcellulose, carboxylic acid, etc. Water-soluble polymers such as cellulose derivatives such as methylcellulose, styrene maleic anhydride copolymer alkali salts, isobutylene maleic anhydride copolymer alkali salts, polyacrylic acid alkali salts, alginate alkali salts, polyacrylamide, casein, gelatin, etc. Various latexes such as , styrene/butadiene copolymer, polyurethane, polyvinyl acetate, and polyacrylic acid can be used.

Furthermore, depending on the application, waxes such as paraffin wax, carnauba wax, polyethylene wax, and methylol stearamide, and lubricants such as zinc stearate and calcium stearate can be added. , a crosslinking agent for crosslinking the binder, etc. can be blended. For applications requiring good recording stability, it is preferable to incorporate a preservation improver such as a phenolic antioxidant.

Conventional methods for applying heat-sensitive dyes produced using colorless dyes, color developers, pigments, binders, and other auxiliary agents on supports include blade coaters, air knife coaters, roll coaters, and rods. There are known methods such as a coater. Medications can be similarly adjusted using conventional methods.

As the support used to constitute the heat-sensitive recording material of the present invention, paper, synthetic paper, plastic film, nonwoven fabric, resin edible paper, etc. can be used. Further, in order to adjust the curl of the product after coating the heat-sensitive coloring layer, it is also preferable to coat a water-soluble polymer, latex, etc. on one or both sides of the support. Further, in order to improve the coloring sensitivity and prevent the adhesion of residue to a thermal element such as a thermal head, it is preferable to provide an intermediate layer containing the above-mentioned inorganic or organic filler between the support and the thermosensitive coloring layer.

In order to improve the storage stability of the heat-sensitive recording material of the present invention, an overcoat layer may be provided on the heat-sensitive coloring layer. No. 39078, Special Publication No. 1-174
The method described in No. 78 can be used.

〔Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

First, dispersions A and B in which the following colorless dye is dispersed, dispersions C and D in which a color developer is dispersed, and dispersions E and F in which a sensitizer is dispersed are sandwiched. Wet dispersion was performed using a grinder until the particle size became 1 to 2 μm to prepare a dispersion liquid. The modified polyvinyl alcohol used was Gosselan L-3288, a trade name manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.

In addition, the number of blended parts indicates the number of parts by weight.

3-n-dibutylamino-6-methylene 10 parts 7-anilic fluorane 10% modified polyvinyl alcohol 109 water
20 copies (
Solution B) 3-(N-ethyl-N-isoamyl) 10 parts amino-6
-Methyl-7-anirithufluorane 10% Modified polyvinyl alcohol 10 parts Water 20 parts On a plate 1.1°-Bis(p-hydroxyphenol 10 parts Nyl)propane (bisphenol A) 10 % modified polyvinyl alcohol 10 parts water 20 parts [Liquid D] 4-hydroxy-4'-isopropoxydiphenyl sulfone 10% modified polyvinyl alcohol water 10 parts 10 parts 20 parts Biphenyl 10% modified polyvinyl alcohol water 10 parts 10 parts 20 parts (F solution) m-terphenyl 10 parts 10% modified polyvinyl alcohol 10 parts water
20 parts and 2 and 322hi Yogi (X liquid) ET-500W 5 part 1
0% modified polyvinyl alcohol 5 parts water
15 parts Next, add 10 parts and 15 parts of the above colorless dye dispersions A and B, color developer dispersion CD, sensitizer dispersions E and F, and 30% calcium carbonate dispersion, respectively. Mixed at a blending ratio of 15 parts and 10 parts, and completely saponified polyvinyl alcohol (average degree of polymerization 1000) as the main binder 1
10 parts of 0% liquid was added to prepare thermal paints having the combinations shown in Table 1 below. Callite SA manufactured by Shiraishi Kogyo ■ was used as calcium carbonate.

Each heat-sensitive paint was used as a support at a rate of 45 g/re? A heat-sensitive recording material was obtained by coating the intermediate layer and the heat-sensitive paint on a high-quality paper with a dry weight of 9 to 10 g/rr+2 and 4 to 58/lT11, respectively. The above-mentioned intermediate layer used an inorganic filler layer mainly composed of fired clay, and the ratio of the inorganic filler to the binder was 100:10 (dry weight ratio). Styrene-butadiene latex was used as the binder.

Furthermore, in the heat-sensitive recording material, 5 parts of the fully saponified polyvinyl alcohol 10% solution was added to 25 parts of Liquid X to form a back coat layer on the side of the support on which the heat-sensitive coloring layer was not coated, and the dry weight was 0. .1~2.0 g/m”
A coated sample and a sample using water as the backcoat liquid were prepared, and are indicated as X and water, respectively, in Table 1. Regarding samples in which 10 parts of liquid X was blended in the heat-sensitive coloring layer, * was indicated in Table 1, and samples of Examples 1 to 12 and Comparative Examples 1 to 8 were obtained.

The heat-sensitive recording material on each side shown in Table 1 below, prepared as described above, was heated to a super calender with a Bekk smoothness of 4.
After adjusting the time to be 00 to 600 seconds, (2) Communication printing was performed using a new facsimile HIFAX47 manufactured by Hitachi, and the development of stackability was evaluated in three stages.

The communication chart was conducted using the facsimile test chart No. 013 of the Institute of Image Electronics Engineers of Japan, and the results shown in Table 1 were obtained.

The Examples had a better stacking property improvement effect than the Comparative Examples.

No. table However, in the table ◎・・・・・・Particularly excellent.

O...Excellent.

×・・・・・・Inferior.

As is clear from the results in this table, the heat-sensitive recording materials of each example having a specific configuration of the present invention exhibited good characteristics with extremely little stack development during facsimile communication compared to the comparative example.

Although the above embodiments have been described with reference to specific examples and numerical values of the present invention, it goes without saying that various changes and modifications can be made without departing from the broad spirit and scope of the present invention.

4 others

Claims (1)

[Scope of Claims] 1. A heat-sensitive coloring layer containing as main components a colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the dye precursor is provided on a support. A heat-sensitive recording material characterized in that a back coat layer containing conductive titanium oxide is provided on the side of the support not coated with the heat-sensitive coloring layer, or the heat-sensitive coloring layer contains conductive titanium oxide. A heat-sensitive recording material. 2. In claim 1, between the support and the thermosensitive coloring layer,
A heat-sensitive recording material characterized by having one or more intermediate layers.