JPS60190386A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide the titled material ideal for high-speed recording which is highly excellent in the heat sensitivity and with a better image stability by combining ester hydroxyphthalate and a specified phenol compound as a developer to be used with a leuco dye. CONSTITUTION:A developer obtained by (A) a compound (e.g. 5-hydroxyphthalate demethylester) of formula I (R<1> and R<2> are each lower alkyl, halide alkyl or the like) and (B) a compound (e.g. 2-hydroxy-3-naphthoic amide) of the formula II (R<3> and R<4> are each H, lower alkyl, cycloalkyl or the like and X is -S-, -SO2- or the like), III (R'' is H, phenyl, alkyl or the like) or IV (R<8> is H, phenyl, alkyl or the like) is normally applied on a support such as paper together with a leuco dye to form a heat-sensitive color forming layer. Thus, the desired material is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer.

[Prior art]

Thermosensitive recording materials generally consist of a support such as paper, synthetic paper, or plastic film provided with a thermosensitive coloring layer containing a thermochromic composition as a main component, and can be heated with a thermal head, thermal pen, laser beam, etc. A colored image is obtained. Compared to other recording materials, this type of recording material does not require complicated processing such as development and fixing, can produce records in a short time using relatively simple equipment, and generates less noise and pollutes the environment. Due to its advantages such as 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. The thermochromic composition used in such heat-sensitive recording materials generally consists of a color former and a color developer that causes the color former to develop color thermally, and the color former includes, for example, a lactone, a lactam, or a spiropyran ring-containing composition. Colorless or light-colored leuco dyes are used, and various acidic substances such as organic acids and phenolic substances are used as color developers. A recording material that combines a color forming agent and a color developer has the advantage that the resulting image has a particularly clear color tone, has a high background whiteness, and has excellent weather resistance of the image (dye image). and is widely used.

However, in recent years, heat-sensitive recording methods have replaced other conventional recording methods, and as demand has increased, there has been an increasing demand for improved quality of heat-sensitive recording materials used in this method. faster recording speeds,
Improving the reliability of recorded images has become a major issue.

For example, when using bisphenol A as a color developer,
Although the images are relatively stable, they suffer from slow thermal sensitivity.

〔the purpose〕

As a result of examining various color developers, the present inventors found that hydroxyphthalic acid esters significantly improve thermal sensitivity compared to conventional color developers such as bispha-3=Nol A. However, there is a problem that the image stability over time and oil resistance are inferior to bisphenol A etc.
As a result of intensive studies to solve this problem, we have completed the present invention.

〔composition〕

According to the present invention, in a heat-sensitive recording material having a heat-sensitive color forming layer containing a leuco dye and a color developer, as the color developer,
A thermosensitive recording characterized by using a combination of at least one compound represented by the following general formula (I) and at least one selected from the following general formulas (II), (m), and (IV). Materials provided.

General formula (■): (In the formula, R1 and R2 represent lower alkyl, halogenated alkyl, or cycloalkyl) -4= General formula (■): (In the formula, R'a, R4 are hydrogen, lower alkyl, General formula (■): (wherein, R7 is phenyl, substituted phenyl, alkyl, halogen) The general formula (■) represents alkyl or allyl: (wherein, R8 represents hydrogen, phenyl, substituted phenyl, alkyl (including lower and higher alkyl), alkyl halide, or allyl) General formula (1) Specific examples of compounds represented by are as follows.

5-hydroxyphthalic acid dimethyl ester, 5-hydroxyphthalic acid dicyclohexyl ester, 5-hydroxyphthalic acid di(chloromethyl ester), 5-hydroxyphthalic acid di(bromomethyl ester), etc.

Specific examples of the compound represented by general formula (II) include the following.

4.4'-isopropylidene bis(2,6-dimethylphenol), 4,4'-isopropylidene bis(6
-tertbutylphenol), 2,2'-methylenebis(6-tertbutyl-3methylphenol),
4.4'-n-butylidene bis(6-tert, butyl-3-methylphenol), 4.4'-isopropylidene bis(2,6-dichlorophenol), 4.4'
-isopropylidene bis(2,6-dibromophenol), 4,4'-bis(2,6-dichlorophenol)
sulfone, 4,4'-bis(2,6-dibromophenol) sulfone, etc.

Specific examples of compounds represented by general formula (m) are 1
For example, the following can be mentioned.

2-hydroxy-3-naphthamide, 2-hydroxy-
3-naphthoanilide, 2-hydroxy-3-naphthoic acid-isopropylamide, 2-hydroxy-3-naphthoic acid-octylamide, 2-hydroxy-3-naphthoic acid-stearylamide, 2-hydroxy-3-naphthoic acid-0 -Methoxyanilide, 2-hydroxy-3-naphthoic acid-m-chloroanilide, 2-hydroxy-3-naphthoic acid-chlorobutyramide, salicylanilide, salicyl-〇'-chloroanilide, salicyl-m'-trifluoromethyl anilide, 5-chlorosalicylanilide, etc.

-7-. The present invention is characterized in that phenol compounds of general formulas (U) to (IV) are combined with the hydroxyphthalate ester of general formula (1), and in this case,
Other phenolic compounds, such as bisphenol A, bisphenol B, bisphenol S, benzyl p-hydroxybenzoate.

4.4'-cyclohexylidene bisphenol, 4.
Even if 4'-thiobis(6-tert-butyl-3-methylphenol), 2-hydroxy-3-naphthoic acid and its metal salts, salicylic acid and its metal salts, etc. were used, the intended purpose could not be achieved; In some cases, the background fog is strong, and the background fog is also strong during heat-resistant storage, making it impractical.

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:
Any dye that has been applied to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran dyes are preferably used. Specific examples of such leuco dyes include those shown below.

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-dinithylaminobutaride, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6 -chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane.

2- (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3,
6-bis(jethytvymi/)-9-(0-'yfluornilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7 -(0-chloroanilino)fluoran, 3-dibutylamino-7-(0-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-pyrillospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrillospirane, 3-(2 '-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'- Methoxy-51-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, 11-3-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-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(0 -methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)12
- -5.6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

In the present invention, a thermofusible substance may be further added as necessary, and specific examples of this substance include, for example,
Examples include dimethyl terephthalate, acenaphthene, dimethylnaphthalene, dibenzofuran, and 9-fluorene.

To produce the heat-sensitive recording material of the present invention, a coating solution containing a leuco dye, a color developer, and a binder as main components may be coated on a support such as paper or synthetic paper, and then dried.

Here, the appropriate amounts of the leuco dye, color developer and binder used are 5 to 30% by weight, 40 to 80% by weight, and 2 to 20% by weight, respectively.

Further, compounds of general formula (I) and general formulas (II) to (IV
) The usage ratio of the compound of general formula (n) to 1 part by weight of the compound of general formula (1) is 0.1 to 5 parts by weight of the compound of general formula (n) to (mV).
The proportion is preferably 0.2 to 2 parts by weight.

〔effect〕

The heat-sensitive recording material of the present invention has the above-mentioned structure and has the characteristics of "fast heat sensitivity" and good image stability.
It is suitable as a heat-sensitive recording material for high-speed recording.

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 [Liquid A] 3-(N-methyl-N-cyclohexyl 10 parts amino)-6-methyl-7-anilitufluoran 10% of hydroxyethyl cellulose 1o Aqueous solution 30 [Liquid B] 5-hydroxyphthal Dimethyl acid 30 parts Hydroxyethylcellulose 10% 3o/l aqueous solution 90 parts [Liquid C] Color developer shown in Table 1 10 parts Calcium carbonate 30 5% methylcellulose aqueous solution 40 Water 120/1 Proceed as above. The A, B, and C solutions obtained in
A heat-sensitive coloring layer was provided by coating and drying to obtain heat-sensitive recording paper. The evaluation results are shown in the table below.

Printing was done using a prototype facsimile machine with an applied energy of 2mj.
I did it. In addition, the oil resistance shown in the table was tested by measuring the concentration when cottonseed oil was applied, and the final stability was tested by measuring the concentration after being stored indoors for one week.

In addition, in the above-mentioned clothing, Comparative Example 1 is a case where dimethyl 5-hydroxyphthalate is used alone as a color developer, and Comparative Example 4 is a case where bisphenol A alone is used as a color developer.

As is clear from the following results, the heat-sensitive recording material of the present invention has high sensitivity, has a white background, and provides stable images.

Patent applicant Rico Co., Ltd. Representative Patent Attorney Toshiaki Ikeura 18-

Claims (1)

[Claims] (1) In a heat-sensitive recording material having a heat-sensitive color forming layer containing a leuco dye and a color developer, at least one compound represented by the following general formula (1) and the following general formula (n) are used as the color developer. , (III) and (IV). General formula (I): (In the formula, R1, R1 = represents lower alkyl, halogenated alkyl, or cycloalkyl) General formula (■): (In the formula, R3, R4 are hydrogen, lower alkyl, halogenated alkyl, cycloalkyl, halogen, aryl or aralkyl, or -5-1R' is hydrogen or a lower alkyl group) General formula (■): (In the formula, R7 is hydrogen, phenyl, substituted phenyl. Alkyl, halogenated alkyl or allyl) General formula (■): (In the formula, R8 represents hydrogen, phenyl, substituted phenyl, alkyl, halogenated alkyl, or allyl)