JPH03166983A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To make a thermal recording medium suited for fast recording and make a recorded image stable under high temperature and high humidity conditions as well as control the unnecessary generation of fog on a blank space by adding a specific diglycidyl compound to a thermal recording layer. CONSTITUTION:A thermal recording medium comprising a leuco compound, an organic acid which colors through a reaction with the leuco compound and a binder contains a diglycidyl compound expressed by formula(I) as a shelf life modifier in the thermal recording layer of the medium. In the formula(I), Ar is a phenyl group, a diphenyl group or a naphthyl group. The preferable content of the compound(I) is 1 to 30% of the total solid portion of the thermal recording layer. A paint for the thermal recording layer is prepared by crushing the leuco compound, the organic acid, the compound(I) as a shelf life modifier and, if necessary, additives such as pigment, sensitivity conditioner, in an aqueous medium containing a binder of any appropriate concentration such as polyvinylalcohol, using a crusher such as a ball mill or a sand grinder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium that has excellent storage stability of recorded images and does not reduce the whiteness of blank paper areas.
This invention relates to a heat-sensitive recording material that does not cause sticking or adhesion of residue to the head.

(Prior art and problems to be solved) Heat-sensitive recording paper containing a leuco compound and an organic acid is known, for example, from Japanese Patent Publication No. 45-1
4039, etc., is already known. This recording paper is based on the principle that heat energy is applied to the recording layer to soften or melt the leuco compound, organic acid, and binder, and the two color-forming substances are brought into contact to cause a color-forming reaction. It is used in fields such as facsimile.

The recording characteristics of this recording paper vary depending on the application, but as its usage has become more widespread, it has not only become suitable for high-speed recording, but also has characteristics such as stability of recorded images under high-temperature conditions and the prevention of unnecessary fogging in blank areas. It is required to have the following.

Conventionally, various methods have been proposed for the purpose of improving the archivability of recorded images. For example, JP-A-49-45747 and JP-A-49-54040 propose the addition of various phenol derivatives.

However, in these conventional technologies, (i) the effect of preventing color fading is not sufficient, (ii) the background is covered, (iii) the color fades when a fingerprint is attached to the colored area, and (iv) no color develops. It has drawbacks such as coloring if fingerprints are attached to the surface, making it unsuitable for practical use. Also, JP-A-53-17346, JP-A-53-17347 and JP-A-5-5-3-4
In No. 901, the addition of various resins was proposed, and some of them were found to be effective, but when used as a thermal recording medium, new problems such as sticking and adhesion of residue to the thermal head occurred. Put it away.

Furthermore, diphenylsulfone derivatives have been proposed in JP-A-62-164579, but they cause a large background fog and cannot be used practically.

Therefore, there has been a strong demand for a heat-sensitive recording material that provides better preservation of recorded images than before, does not reduce the whiteness of the blank paper portion, and does not cause sticking or residue adhesion. As a result of extensive and deep consideration of the problems of these conventional storage improvers, the present inventors discovered that the above problems could be solved by using a specific storage improver, and based on this knowledge, Based on this, the present invention has been made.

(Means for Solving the Problems) The present invention was made based on the knowledge that a specific diglycidyl compound has extremely excellent performance as a preservability improving agent for heat-sensitive recording materials.

That is, the present invention provides a heat-sensitive recording material containing a leuco compound, an organic acid that develops a color by reacting with the leuco compound, and a binder, in which the following general formula (Process ):0 U (In the formula, ^r represents a phenyl group, a diphenyl group, or a naphthyl group.) A gloss-sensitive recording material containing a diglycidyl compound (hereinafter referred to as compound (1)) is provided.

In the above formula (I), the phenyl group, diphenyl group and naphthyl group may have a substituent, and the substituent is:
Examples include halogen and an alkyl group having 1 to 4 carbon atoms.

The heat-sensitive recording material of the present invention comprises a leuco compound, an organic acid as a color developer, a binder, and a compound (
It consists of a heat-sensitive recording layer containing 1) coated on a support.

The content of compound (I) is 1 to 1 based on the total solid content of the heat-sensitive recording layer.
A sufficient effect can be obtained if the content is 50% by weight (hereinafter abbreviated as %), but the content is preferably 1 to 30%.

The leuco compounds used in the present invention are colorless to light-colored substances that develop color by reacting with organic acids, such as triphenylmethane, triphenylmethane phthalide, fluoran, leuco auramine, diphenylmethane, Examples include various derivatives such as phenothiazine, phenoisazine, spiropyran, indoline, and indigo derivatives. Preferred leuco compounds include, for example, crystal violet lactone, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-ethyl-P-}
Luidino〉-6-methyl-7-anilinofluorane, 3
-diethylamino-6-methyl-7-(ortho, para-dimethylanilino)fluorane, 3-pyrrolidino-6-
Methyl-7-anilinofluorane, 3-biperidino-6
-Methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(orthochloroanilino)fluorane, 3 -diethylamino-7
−(Metatrifluoromethylanilino)fluorane,
3-diethylamino-6-methyl-chlorofluorane,
3-diethylamino-6-methyl-fluorane, 3-cyclohexylamino-6-chlorofluorane, 3-(
N-isoamyl-N-ethylamino)-6-methyl-7
-anilinofluorane and 3-dibutylamino-6=methyl-7-anilinofluorane.

These leuco compounds can be used alone or as a mixture of two or more. The leuco compound is preferably contained in an amount of 1 to 20%, preferably 5 to 15%, of the total solid content of the heat-sensitive recording layer.

The organic acid used in the present invention is a substance that is solid at room temperature, melts when heated, and becomes a color developer when it comes into contact with a leuco compound, and includes various phenolic substances, fatty acids, aromatic carboxylic acids, etc. . Examples include gallic acid, salicylic acid, 1-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-p-toluic acid, 3.5-xylenol, thymol, p- tert-butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4
-Hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4
-tert-octylcatechol, 4-4' 1 sec
-butylidenephenol, 2,2'-dihydroxydiphenyl, 2,2'-methylenebis(4-methyl-6-t
ert-butylphenol)2.2'-bis(4'-
Hydroxyphenyl〉propane (also known as bisphenol A), 4.4'isopropylidene bis(2-ter
t-butylphenol), pyrogallol, phloroglucin, pro-glucincarboxylic acid, p-methylphenol, p-phenylphenol, 4.4'-cyclohexylidene diphenol, 4.4'-(1-methyl-n-hexylidene) 〉Diphenol, 4.4'-isobropylidene dicatechol, 4.4'-benzylidene diphenol,
4. 4'-isopropylidene bis(2-chlorophenol), 3-phenylsalicylic acid, 3,5-di-te
rt-butylsalicylic acid, 1-oxy-2-naphthoic acid, gallic acid ester, salicylic acid ester, p-hydroxybenzoic acid ester, 4-hydroxyphthalic acid ester, 2-(4-hydroxyphenyl)-2-(3'- Hydroxyphenyl〉broban, 4,4'-dihydroxy-3,3'-diisobrobyldiphenyl-2,2'-
Examples include propane.

In the present invention, the amount of organic acid used is preferably 1 to 50%, preferably 10 to 40% of the total solid content of the heat-sensitive recording layer.

The binder used in the present invention is mainly a water-soluble binder, which separates and fixes the coloring agent dispersed in fine particles from each other, and includes polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, Examples include acrylic acid, casein, gelatin, starch and derivatives thereof.

The amount of binder used is 1 to 35% of the total solid content of the heat-sensitive recording layer.
, preferably a ratio of 10 to 30%.

The heat-sensitive recording layer of the present invention may optionally contain other additives such as clay, silica, calcium carbonate, etc.
Inorganic or organic pigments such as aluminum hydroxide, talc, titanium oxide, zinc oxide, waxes, antioxidants for storage stability, ultraviolet absorbers, various fatty acid metal salts to prevent stickiness, water resistance to improve water resistance. A curing agent, a phenol resin, a surfactant, etc. can be added.

The paint for a heat-sensitive recording layer of the present invention comprises the above-mentioned leuco compound,
An organic acid, compound (1) as a preservability improver, and additives such as pigments and sensitivity regulators as needed are mixed in an aqueous medium containing an appropriate concentration of a binder such as polyvinyl alcohol in a ball mill. It is generally prepared by grinding and dispersing using a grinder such as a sand grinder. It is advantageous in terms of color development efficiency to make each constituent material as fine as possible, and 0. It is preferable to atomize the particles to a particle size of 5 to 3 μm. The heat-sensitive coating material thus obtained is applied to a support described below and dried to obtain the heat-sensitive recording material of the present invention.

Application can be done using a regular blade coater, air knife coater,
This can be done using a bar coater, reverse roll coater, or the like.

The support used in the present invention generally includes high-quality paper,
Various types of paper are used, including medium-quality paper and coated paper, but glass fiber sheets, plastic sheets, film-laminated papers, and the like can also be used as the support.

(Effects of the Invention) According to the present invention, a heat-sensitive recording medium which has excellent storage stability and is free from sticking and adhesion of residue to the head is provided.

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

Example 1 The following solutions A and B were prepared by separately dispersing them in a paint shaker (manufactured by Toyo Seiki) for 10 hours.

8. Liquid: Zinc stearate 5g Polyvinyl alcohol 12% liquid 35g Water B liquid Bisphenol A 50g 15g Zinc stearate 3g Polyvinyl alcohol 12% liquid 35g Water
47g Next, 8 liquids 95
g, 110 g of liquid B, 50 g of 12% polyvinyl alcohol liquid, and 1 g of synthetic silica P-832 (manufactured by Mizusawa Chemical Co., Ltd.)
Add 5g and 60g of water, stir to make a coating liquid, and apply this coating liquid to the surface of 50g/m'' high-quality paper using a Mayer bar so that the coating amount after drying is 8g/m'. The mixture was coated and dried to obtain heat-sensitive recording paper.

Example 2 In the formulation of liquid B used in Example 1, 1 was added instead of compound A.
．． 5-diglycidyloxynaphthalene (melting point 166°C)
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that [Compound B] was used.

Example 3 In the formulation of liquid B used in Example 1, 1,4-diglycidyloxybenzene (melting point 110°C) was used instead of compound A.
A thermosensitive recording paper was obtained in the same manner except that [Compound C] was used.

Example 4 In the formulation of Solution B used in Example 1, 4.47-diglycidyloxydiphenyl (melting point 152) was used instead of Compound A.
℃) A thermosensitive recording paper was obtained in the same manner except that [Compound D] was used.

Comparative Example 1 A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that Compound 8 was omitted from the formulation of liquid B used in Example 1.

Comparative Example 2 In the formulation of liquid B used in Example 1, 4,4'-butylidene bis(3-methyl-5-tert) was used instead of compound A.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 1-butyl-m-cresol) was used.

Comparative Example 3 Thermal reaction was carried out in the same manner as in Example 1, except that 4,4'-thiobis (6-tert-butyl-m-cresol) was used in place of Compound 8 in the formulation of liquid B used in Example 1. I got the recording paper.

Comparative Example 4 In the formulation of liquid B used in Example 1, 2,2'-methylenebis(4-methyl-5-ter
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that t-butylphenol) was used.

Comparative Example 5 Same as Example 1 except that terpene-modified phenol resin was used instead of compound A in the formulation of liquid B used in Example 1.
A thermosensitive recording paper was obtained in the same manner as above.

Comparative Example 6 Example 1 except that roseoctylphenol resin was used instead of compound A in the formulation of liquid B used in Example 1.
A thermosensitive recording paper was obtained in the same manner as above.

Comparative Example 7 The same procedure as in Example 1 was used except that 4,4'-bisglycidyloxy)diphenylsulfone (melting point i: 60°C) was used instead of Compound A in the formulation of Solution B used in Example 1. A thermosensitive recording paper was obtained.

Example 5 A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that pendylvala hydroxybenzoate was used instead of bisphenol A in the formulation of liquid B used in Example 1.

Example 6 In the formulation of liquid B used in Example 1, n-butyrubis(4-hydroxyphenyl) was used instead of bisphenol A.
A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that acetate was used.

Example 7 Thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that 4-hydroxy-4'-isoproboxydiphenylsulfone was used in place of bisphenol A in the formulation of liquid B used in Example 1. .

Test of heat-sensitive recording material The sample thus obtained was evaluated by the test method described below.

1. High temperature/humidity storage test After printing with a commercially available thermal facsimile device UF-1000 (Matsushita Densen @), it is stored for 24 hours under two conditions: temperature 40℃ and humidity 90%RH, and temperature 60℃ and dry state (15%RH). Then, the skin concentration of the sample before and after storage was measured.

Separately, the density of the printed area of the sample before and after storage was measured, and the residual rate of the density of the printed area after storage was determined from the following formula.

2. Light resistance storage test After printing with UF-1000 and exposing to sunlight for one week, the background density of the sample was measured. The density of the printed area after separate exposure was measured, and the survival rate of the printed area was determined in the same manner as in the storage test.

3. Sticking Test Printing was performed using UF-1000 in an atmosphere of 0° C., and the presence or absence of sticking was examined at that time.

4. Dust adhesion test 3m printing was performed using UP-1000 in an atmosphere of 20°C, and dirt around the thermal head was visually determined.

All color density measurements were performed using Macbeth Densitometer RD-5.
I went with 14 type.

The results of the above tests are shown in Table-1.

It can be seen from Table 1 that by adding Compound (I), a thermosensitive recording material having excellent storage stability and no sticking and no residue adhering to the head can be obtained.

1. Display of incidents 1999 Patent Application No. 307398 2. name of invention Feeling heat Record record body 3. Person who makes amendments Relationship with the incident

Claims (1)

[Scope of Claims] A heat-sensitive recording material comprising, on a support, a heat-sensitive recording layer containing a leuco compound, an organic acid that reacts with the leuco compound to develop a color, and a binder, wherein the heat-sensitive recording layer contains: Contains a diglycidyl compound represented by the following general formula (I): ▲Mathematical formulas, chemical formulas, tables, etc.▼... (I) (In the formula, Ar represents a phenyl group, diphenyl group, or naphthyl group.) A heat-sensitive recording material characterized by the following properties.