JPS58181686A - Thermal recording sheet - Google Patents

Abstract

PURPOSE:To obtain a recording sheet with a gradation property which is better in the rising of the color development density at the moment of heating by using one or more kinds of specified 2, 2'-methylene diphenyl compounds as developer for a thermal recording sheet. CONSTITUTION:2,2'-methylenediphenol compound as given by the formula (where, R represents hydrogen, alkyl group with C1-C12, cycloalkyl group with C3- C10, alalkyl group or phenyl group with C7-C10, which may be identical or different) and a coloring agent developing color by a melt reaction with the developer are separately dissolved or dispersed in water or a solvent and mixed together. An appropriate binder is added to the mixture and the mixed liquid thus obtained is applied on a supporting body such as paper and synthetic resin film and dried. The quantities of the components shall be 1-15pt.wt. for the coloring agent, 1-95pt.wt. for the developer of the formula and 1-40pt.wt. for the binder.

Description

[Detailed description of the invention] 4 ＼ Busy Mei is related to heat-sensitive 4-pilot notes.

Conventionally, color formers (hereinafter referred to as "color formers") consisting of deuterium-donating color-forming compounds such as triphenylmethane, fluoran, fetchazide, auramine, and subirohirano compounds, and viscosity-based color formers have been used. (activated clay, etc.), a phenol compound, an aromatic carboxylic acid, and a solid acid such as an aromatic head III gold maple salt. Utilizing the coloring reaction with a blood-tinting agent, the two color-forming substances are brought into contact with heat to create a colored image. The so-called dye-colored thermosensitive recording notebook is well known.

In general, thermal recording sorting has the following performance conditions:
It itself is colorless or light-colored, and not only does it have vague color performance that does not change directly after manufacturing or after long-term storage, but it also requires that the color image is robust and sufficiently stable against light and humidity. There must be something that can be manufactured. Already proposed blood-tinting agents for heat-sensitive recordings and notebooks coated with the same have advantages and disadvantages in terms of bioactivity. Because it is coated, the color develops and fogs before it is heated during copying, and the preservation of color painting methods such as light fastness and water resistance is disadvantageous. There are drawbacks to this, and furthermore, there is a disadvantage in that the iU2 record/-
I'm looking forward to it. Particularly in recent years, there has been a need for a new color developer with a short pulse width and gradation properties for use in this printer, with a good rise in color density upon heating.

The inventors of the present invention have endeavored to provide a heat-sensitive recording sheet with a good rise in color density upon heating.
As a result of our efforts, we succeeded in inventing a heat-sensitive I-printing sheet using the novel color developer described below, and solved this problem.

That is, 4〈thermal recording of the invention-1・r, general formula 1′
1) (wherein J< is hydrogen, C4 to C1, alkyl group,
represents a C6-C,,,/chloroalkyl group, an aralkyl group of C7-C1fJ, or a noenyl group, and η may be the same or different. ) is characterized by containing one or two or more of the gumeethylene diphenol compounds represented by As a result, the rise in color density is extremely sharp, and the color density is equivalent to or higher.

The curly colored image has excellent light fastness and water resistance, and has the advantage that a decrease in density over time is very small, and a heat-sensitive recording sheet that is very advantageous in terms of handling, bending, and storage stability can be obtained at a low cost.

The color developer represented by the general formula (1) in the present invention includes the following exemplified compounds, but is not limited thereto.

2,2'-7hydroxydiphenylmethane, 2,2'-
/hydroquine-5-methylphenylmethane, 2,2
'-dihydroxy-5-iso-probylciphenylmecune, 2,2'-dihydroquine-5-tert-butyl/phenylmeth7.2.2'=dihydroquine-5-1e
rt-octyldiphenylmethane, 2.2'-7hydroxy-5-α-methylbenzyl-diphenylmethane, 2
．． 2'-7hydroquine-5,5'-dimethyl/phenylmethane, 2,2'-dihydroquine-5,5'-ethyldiphenylmethane, 2,2'-dihydroxy-5,5'
-2-1so-propylumphenylmethane, 2, gauge hydroquine-5,5' -7-tert-butyl/
Phenylmethane, 2,2'-dihydroxy-5,5'-
Di-tert-octyldiphenylmethane, 2.
2'-7 Hydroquine-5,5'-ncyclohequinluciphenylmethane, 2.2'-7 Hydroquine-5,5'-C α, α-7 Methyl // Ruphenylmethane, 2.2
'-dihydroxy-5,'-diphenyldiphenylmethane, 2,2'-dihydrok-7-5-ethyl-5'-methyldiphenylmethane, 2,2'-nohydrok-7-
5-sec-phthyl-5'-methyl 7-phenylmethane,
2.2'-nhytroquine-5-1ert-phthyl-5'
-methylsinphenylmethane, 2,2'-dihydro-J
t-'y-5-1ert-octyl-51-methyl-diphenylmethane, 2.2'-dihydroxy-5-cyclohexyl-57=methylphenylmethane, 2.2'-
7hydroxy7'-5-/chlorohexyl-5'-5ec-
Butyldiphenyl meta/,2,2'-)hydroquine-5
-α,α--/methylbenzyl-5'-methyldiphenylmethane, 2,2'-dihydroxy-5-α,α-dimethylbenzyl-5'-tert-butyl/phenylmethane, 2,2'-dihydroxy-7- 5-phenyl-5'-
Examples include ethyldiphenylmethane.

A general method for producing the heat-sensitive recording sheet of the present invention will be described below. As the coloring agent, various types of coloring agents that develop color by melting reaction with the color developer represented by the general formula (1) can be used. For example, ro, 6'-bis(4-dimethylaminophenyl)
-6-dimethylaminophthalide (crystal violet lactone), 6-diethylamino-6-methyl-fuchlorofluorano, ro-diethylamine-7-chlorofluorane, ro-7-lyrohexylamino-6-chlorofluoran , 6-dinitylamin-7-bennoradnofluorane, 6-diethylamine-6-methyl-phenylamino-fluorane, 1,3,6-drimethylindolino 6'-chloro-8'-methoxy-spiropyran, 6-methyl-2 , 2'-spirobis (henzo 1[]chromene) and the like.

”-colorless or light-colored coloring agent, general formula (1)
A mixed solution is prepared by thoroughly mixing a color developer represented by the following with a solution or dispersion of a binder in water or an organic solvent. The list of binders used in the preparation of this mixture includes styrene butaphene polymer, holvinyl alcohol, carboxydimethyl cellulose, hydroquine ethyl cellulose, polystyrene, vinyl chloride-vinyl acetate copolymer, synthetic polymers such as gum arabic, and natural starch. or naturally modified polymers.

Examples of solvents that can be used include organic solvents such as benzene, toluene, acetone, methylene chloride, ethyl acetate, and cyclohexane, and water.

The resulting mixed solution is applied to a support such as paper, natural or synthetic resin film, and dried.

The liquid mixture may be poured into a support. The above mixing force method and coating method involve mixing the thermal recording material of the present invention with a binder solution, separately mixing the color developer with the binder solution, and then mixing the two mixed solutions and applying the mixture to the support. Alternatively, both mixed solutions can be divided into two parts and applied to the support. Both liquid mixtures can be applied to the same side of the support, or to separate or different supports.

There are various relative amounts of each component that makes up a thermal recording notebook.
A suitable range is 1 to 15 parts by weight of color former, color former (general formula (
D) 1 to 95 parts by weight, and 1 to 40 parts by weight of binder. This weight is in dry condition.

The heat-sensitive recording sheet of the present invention does not cause color fog even though the color forming agent and the color developer are in mutual contact with each other during manufacturing and from coating and drying to heating.
・It has good stability over time with no deterioration in coloring performance even when exposed to light, instantly develops color when heated, and the colored image is lightfast.
Extremely good water resistance.

The present invention will now be explained by way of examples.

The following methods were used to measure and evaluate various performances of the recording sheet.

1) Color density recording sheet with Thermotest Rhodiaceta (SETA)
Heating time using RAII4, Model 7401)
Heating element/recording sheet pressure when heated for 5 seconds 10? /cr
1.Heat to develop color under heating temperature range of 60 to 180°C. Reflectance (1) was measured using a TSS type Hunter colorimeter (manufactured by Toyo Seiki Co., Ltd.) using an amber filter for 10 minutes after color development by heating.

The lower the reflectance, the higher the color density.

2) Light resistance of colored image The sheet colored by the method in 1) was irradiated with light for 60 minutes to 4 hours using a carbon arc lamp, and the same as in 1)...
Measured with an inner colorimeter, ■0: Reflectance of uncolored notebook,
(2) S: Reflectance of colored sheet before irradiation; (2) n: Reflectance of colored sheet after n hours of irradiation.

The higher the residual rate, the better.

(b) Storage stability After leaving the uncolored and colored recording sheets at 25°C for 6 months, the reflectance of the uncolored and colored notes before being left was set as Ko and K, and the reflectance after being left was determined respectively. , ni'. The smaller the difference between K-Ko and B-KO', the better the storage stability.

4) Water resistance The colored recording sheet was stored in water for 2 hours, and changes in the density of the colored image were observed with the naked eye.

Example 1 Solution A: Crystal Violeno Trafton 77 water
167 B i: 2. f-dihydroquine: solemethane 7v1o wt% polyvinyl alcohol 30fI water 132 Dispersions of the above A and B solutions were separately prepared using a sand grinding mill, and A and B were mixed with 6 parts and 67 parts, respectively. The mixture is coated on high-quality paper at a dry coating amount of 25 to 5.5 f/rr and dried to obtain a heat-sensitive recording sheet.

The performance of the obtained thermosensitive recording sheet was evaluated.

The results are shown in Table-1.

Examples 2 to 11 and Comparative Example 1 A thermosensitive recording sheet was obtained in Example 1 except that only the color developer was replaced with another color developer. The performance of the obtained thermosensitive recording sheet was evaluated. Table 1 shows the color developer used and the results of performance evaluation.

Claims (1)

[Claims] 1) General formula (1) (wherein, R is hydrogen, 'alkyl of 01 to CI2, C3
2゜2'- represented by 3.) which represents a cycloalkyl group of ~01o, an aralkyl group or a noenyl group of c7''-C10, and may be the same or the heel of each other.
Thermal recording characterized by containing 1,000 or 200 mm of methylene/phenol compound as a color developer/-
1.