JPS62113590A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material showing little fading of images due to oils or fingerprints and having excellent thermal response characteristics, by using a monoester compound of bis(4-hydroxyphenyl)sulfone of a specified formula as a color developer. CONSTITUTION:A monoester compound of bis(4-hydroxyphenyl)sulfone of formula (I), wherein R1 is hydrogen or methyl, is used as a color developer, in a thermal recording material utilizing a color forming reaction between a leuco dye and the color developer. The compound ensures excellent stability of a developed color image part, and rarely generate image deterioration due to temperature or moisture or image fading due to a plasticizer, oil or the like. A color developer consisting of a known phenolic substance, inorganic or organic acidic substance or derivative thereof may be jointly used, if required. The color develops are preferably used in an amount of 2-6pts.wt. per 1pts.wt. of the leuco dye, and the color developer of formula (I) is not less than 20wt% based on the total amount of the color developers, preferably, not less than 50wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to improvements in heat-sensitive recording materials containing leuco dyes as color formers.

[Prior art]

Thermosensitive recording materials generally consist of a support such as paper, synthetic paper, or plastic film, on which a thermochromic FJ'j whose main component is a thermochromic composition is provided. By doing so, a colored image can be obtained. Compared to other recording materials, this type of recording material does not require complicated processing such as development and fixing, and records can be obtained in a short time using relatively simple equipment, and it generates less noise and pollutes the environment. Due to its advantages such as low cost and low cost, it is used not only for copying books and documents, but also as a recording material in a wide range of applications such as electronic computers, facsimile machines, ticket vending machines, labels, and recorders. Thermochromic compositions used in such heat-sensitive recording materials generally consist of a color former and a color developer that causes the color former to develop color when heated. As the color former, for example, a composition having a lactone, lactam or spiropyran ring Colorless or light-colored leuco dyes are used, and various acidic substances such as organic acids and phenolic substances are used as color developers. This recording material that combines a color forming agent and a color developer has the advantage that the color tone of the image is particularly clear, the whiteness of the background is high, and the weather resistance of the image is also excellent, so it is widely used. has been done.

Conventionally, bisphenol A and P-hydroxybenzoic acid esters have been used as color developers for leuco dyes, but these phenols have high color density but lack the stability of colored images, so they cannot be left alone. In addition to the problem that the concentration decreases when it comes into contact with oils and fats such as fingerprints, the concentration also decreases. These phenomena occur not only when using phenols but also when using general organic acids.

There is a strong need to overcome this problem. As seen in JP-A-59-38091, the use of metal compounds such as aluminum chloride has been proposed as a color developer that provides images with good stability, but when this is applied to heat-sensitive recording materials. Although one image is stabilized, it is currently difficult to apply it to heat-sensitive recording materials because of the initial background color development.

〔the purpose〕

The present invention overcomes the problems of the prior art, viz.

It is an object of the present invention to provide a heat-sensitive recording material which is highly sensitive, has excellent fingerprint coloring resistance and oil resistance, has almost no background coloring, and has improved reliability.

〔composition〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, bis(4-hydroxyphenyl) represented by the following general formula (1) is used as the color developer.
A heat-sensitive recording material characterized by using a sulfone monoester compound is obtained.

(In the formula, R1 represents a hydrogen atom or a methyl group.) Specific examples of the compound of the general formula (1) used as a color developer in the present invention include the following compounds.

(Bisphenol S monoacrylate) (Bisphenol S monomethacrylate) Compared to conventional color developers such as bisphenol A, the bis(4-hydroxyphenyl) sulfone monoester compound represented by the general formula (I) has The stability of the colored image area is excellent, and therefore there is almost no image deterioration due to temperature and humidity, or image decolorization due to plasticizers, oil, etc.

In addition to the compound represented by the general formula (1), the color developer used in the present invention may include conventionally known phenolic substances, inorganic/organic acidic substances, and their derivatives. A coloring agent can also be used in combination.

The color developer used in the present invention is generally 1 to 10 parts by weight, preferably 2 to 6 parts by weight, per 1 part by weight of the leuco dye.
The amount of the color developer of general formula (I) used in the present invention is 20% by weight or more, preferably 50% by weight or more of the total color developer.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. . Specific examples of such leuco dyes include those shown below.

3.3-bis(P-dimethylaminophenyl)-phthalide, 3.3-bis(ρ-dimethylaminophenyl)-6-cyphthylaminophthalide (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, 3-cyclohexylamino-6- Chlorfluorane, 3-dimethylamino-5,7-cyphthylfluorane, 3
-diethylamino-7-talolofluorane, 3-diethylamino-7-methylfluorane.

3-diethylamino-7,8-benzfluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-1~ly-N-ditylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-ani Linofluorane, 2- (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3,
6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(o-chloroanilino) ) fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane.

3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluorane.

Benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 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, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-( N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane.

3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-ρ-1-luidino)-7-(α-phenylethylamino)fluoran.

3-diethylamino-7-(0-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-2enylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane.

3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

3.6-dimethyl-xyfluorane, 3-(P-dimethylaminophenyl)-3-phenylphthalide.

3-di(l-ethyl-2-methylyldol)-3-yl-phthalide, 3-diethylamino-6-phenyl-7-azafluorane, 3.3-bis(p-diethylaminophenyl)-6-cyphthyla Minophthalit, 2-bis(p-dimethylaminophenyl)methyl-5-
Dimethylamino-benzoic acid, 3-(ρ-dimethylaminophenyl)-3-(p-dibenzylaminophenyl)phthalide, 3-(N-ethyl-Nn-amyl)amino-6-methyl-7-aniritfur Oran et al.

In the present invention, one of the compounds represented by the above general formula
A species or two or more species are used as a color developer, and this product can be used in combination with a conventional color developer. As such a color developer, various electron-accepting substances that react with the leuco dye and develop color when heated are applied,
Specific examples thereof include phenolic substances, organic or inorganic acidic substances, and esters and salts thereof as shown below.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-jer
t;-Butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene Screw (2,6
-dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4,4'-isopropylidene bis(2-methylphenol), 4,4'
-isopropylidene bis(2,6-cyphthylphenol), 4,4'-isopropylidene bis(2-cyphthylphenol),
butylphenol), 4.4'-5ec-butylidenediphenol, 4,4'-cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis(2-methylphenol), 4-tertnibutylphenol, 4-phenylphenol , 4-hydroxydiphenooxide, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2,2'-thiobis(4 , 6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycin, phloroglycin carboxylic acid, 4-tertnioctylcatechol, 2,
2'-methylenebis(4-chlorophenol), 2.2
'-Methylenebis(4-methyl-6-sierheaptylphenol), 2,2'-dihydroxydiphenyl, ρ
-Ethyl hydroxybenzoate, ρ-propyl bitroxybenzoate, butyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, P-hydroxybenzoate-P-
Chlorbenzyl, 〇-thalolbenzyl P-hydroxybenzoate, P-methylbenzyl P-hydroxybenzoate, n-octyl P-hydroxybenzoate, benzoic acid, zinc salicylate, ■-hydroxy-2-naphthoic acid , 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis(4-hydroxyethyl) sulfide, 2-
Hydroxy-P-1~ruylic acid, 3,5-jet
, -zinc butylsalicylate, 3,5-jcrt;-
tin butylsalicylate, tartaric acid, oxalic acid, maleic acid,
Citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, thiourea derivatives, 4-hydroxythiophenol derivatives, etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol,
Starch and its derivatives, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose,
Methylcellulose.

Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/
Acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/
In addition to water-soluble polymers such as maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymers, polyacrylic acid, polyacrylic acid esters, and chloride Vinyl/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer,
Latexes such as styrene/butadiene/acrylic copolymers can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, tr
Auxiliary additive components used, such as fillers, surfactants,
A thermofusible substance (or lubricant), etc. can be used in combination.

In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-
Organic fine powders such as formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned, and examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts, as well as various Waxes, condensates of aromatic carboxylic acids and amines, Anbu, aromatic acid phenyl esters, high-grade glycols, 3.・Dialkyl 1-epoxy-hexahydrophthalate, higher ketone,
Examples include other thermofusible organic compounds having a melting point of about 50 to 200°C.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper 1 synthetic paper or a plastic film, and drying it. It is used in the field of recording, especially as a heat-sensitive recording material for high-speed recording, which requires high image stability.

The heat-sensitive recording material of the present invention is used in various fields, but in particular, it takes advantage of the above-mentioned excellent color image stability,
It can be advantageously used as a heat-sensitive recording type label sheet or a heat-sensitive recording type magnetic ticket paper. In the case of a heat-sensitive recording type label sheet, a heat-sensitive coloring layer containing the above-mentioned fluoran compound and phenolic compound is provided on one side of the support,
A release mount may be provided on the other side of the support via an adhesive layer, and in the case of magnetic ticket paper, instead of this release mount,
A magnetic recording layer containing a ferromagnetic material and a binder as main components may be provided.

Further, in the present invention, the leuco dye, the color developer, and the auxiliary component used as necessary can be contained in the same coating layer or in separate coating layers.

Further, an undercoat or an overcoat can be provided if necessary, and materials that can be used here can be arbitrarily selected from the binders, fillers, waxes, etc. described above.

〔effect〕

The heat-sensitive recording material of the present invention has the general formula (r) as a color developer.
By using the bis(4-hydroxyphenyl) sulfone monoester compound represented by the formula, there is less image discoloration due to oil and fingerprints compared to conventional heat-sensitive recording materials, and it also has excellent thermal responsiveness. .

〔Example〕

The present invention will now be explained in more detail with reference to Examples.

Note that the following parts and percentages are all based on if.

Example 1 [Liquid A] 3-(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-anirite fluorane 10 parts 10% aqueous solution of hydroxyethylcellulose 10 parts water

80 parts [Liquid B] Bisphenol S monoacrylate 10 parts Calcium carbonate 20 parts 10% polyvinyl alcohol 10 parts Water
60 parts of each of the mixtures having the above composition were mixed using a sand glider.
[Liquid A] and [Liquid B] were prepared by pulverizing and dispersing for ~4 hours.

Next, [Liquid A] and [Liquid B] were mixed and stirred so that the weight ratio was 1=3 to prepare a heat-sensitive coating solution, and the dry coating amount was applied to 52 g/r# (volatized) commercially available high-quality paper. Labo Cochin Blonde was coated and dried so that the weight was approximately 5.0 g/rf.

This coated paper was calendered to a surface smoothness of 700 to 200 seconds to prepare a heat-sensitive recording material of the present invention.

Example 2 A heat-sensitive recording material of the present invention was prepared in the same manner as in Example 1 except that bisphenol S monoacrylate in [8 liquids] was replaced with bisphenol S monomethacrylate.

Comparative Example 1 A comparative heat-sensitive recording material was obtained in the same manner as in Example FF & Example 1, except that the bisphenol S monoacrylate in [Liquid B] was replaced with benzyl P-hydroxybenzoate.

Comparative Example 2 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1 except that bisphenol S monoacrylate in [liquid B] was replaced with bisphenol S.

The above heat-sensitive recording materials were tested for image density and decolorability with oil. The results are shown in Table-1. In addition, each test method was performed as follows.

■Image density tester electronic component■, printing experimental equipment with thin film head, head power 0.45W/dot, 1 line recording time 2
0IIIs/Q, scanning line density 8X3.85 door 1”/
Printing was performed with a pulse width of 2.2 ms under the conditions of
l:, en-106).

■Skin density: The uncolored area was similarly measured using a Macbeth densitometer.

(2) Oil resistance: Cottonseed oil was applied with absorbent cotton to the sample whose image density was measured in (1) above, and after being left for 24 hours, the image density and background area were measured.

Table 1 As is clear from the results in Table 1, the heat-sensitive recording material of the present invention has a higher density and excellent stability in the image area than conventional materials.

Claims (1)

[Claims] (1) A heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, characterized in that a monoester compound of bis(4-hydroxyphenyl)sulfone represented by the following general formula is used as the color developer. A heat-sensitive recording material. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 represents a hydrogen atom or a methyl group.)