JPS62176879A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having excellent light fastness and excellent in a head matching property, by adding a specific benzotriazole compound to an undercoat layer and a protective layer. CONSTITUTION:In a thermal recording material provided with a protective layer based on a water-soluble resin and a filler, a benzotriazole ultraviolet absorbent represented by formula (wherein R1, R2 and R3 are a hydrogen atom, a halogen atom, an alkyl group, an aryl group and a cycloalkyl group) is contained in an undercoat layer and the protective layer and a thermal color forming layer based on a leuco dye and a coupler is held between the ultraviolet absorbent-containing layers to make it possible to obtain the thermal recording material not generating fog or the lowering in a color forming property in its thermal color forming layer and having excellent light fastness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording sheet, and more specifically, the present invention relates to a heat-sensitive recording sheet, and more specifically, a color-forming component comprising a normally colorless or slightly light-colored leuco dye and a color developer that reacts with the leuco dye under heat to develop a color. This invention relates to an improvement in a heat-sensitive recording material in which a heat-sensitive coloring layer containing a heat-sensitive color forming layer is formed on a support.

[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. A colored image can be obtained by heating with, etc. Compared to other recording materials, this type of recording material has the advantage that recording can be obtained in a short time with a relatively simple device without the need for complicated processes such as development and fixing, and that it produces less noise and environmental problems.
Due to the advantages of low t-contamination and low cost, it is used not only for copying one book or one document, but also as a recording material in a wide range of applications such as computers, facsimiles, ticket vending machines, labels, and recorders. .

In recent years, product information, sales management, corresponding product systemization, PO5 (1'oint, of 5ale)
) system has advanced, and heat-sensitive recording materials are being used as recording materials.

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. Examples of the color former include lactones, lactams, Colorless or light-colored leuco dyes containing a spiropyran ring have been used, and alkaline acids, phenolic acids, and the like have been used as color developers.

However, this type of recording material has the disadvantage that the light resistance of the image area and the background area, that is, the density of the image area decreases significantly when exposed to fluorescent lamps or sunlight for a long time, and the color change of the background area is significant. for this shortcoming.

Improvements using ultraviolet absorbers have been attempted in the past, and it has been reported that, for example, the addition of ultraviolet absorbers into the protective layer on the heat-sensitive coloring layer is quite effective.

However, the back side of thermal paper used for tags in POS systems is often exposed to light, and in addition to changes on the back side of the support, ultraviolet rays transmitted through the support can discolor the background of the thermosensitive coloring layer and reduce the density of the image area. Since this could not be ignored, further improvements were desired.

〔the purpose〕

The purpose of the present invention is to provide excellent light resistance, that is, even when both the front and back surfaces are exposed to fluorescent light or sunlight for a long time, there will be very little change in the back side, image fading, or background discoloration, and there will be no head matching. An object of the present invention is to provide a heat-sensitive recording material that is excellent in performance and reliability.

[Structure] According to the present invention, as the first invention, an undercoat layer containing a water-soluble resin and a filler as main components is provided on a support,
A heat-sensitive recording material in which a heat-sensitive color forming layer containing a leuco dye and a color developer as main components is provided on the undercoat layer, and a protective layer containing a water-soluble resin and a filler as main components is further provided on the heat-sensitive recording material. In the layer and protective layer, the following general formula [1]
By adding a benzotriazole compound represented by.

A heat-sensitive recording material having extremely excellent light resistance is provided, and as a second invention, a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on a support, and a water-soluble resin and a filler are coated thereon. In a heat-sensitive recording material provided with a protective layer containing a water-soluble resin as a main component and a back coat layer containing a water-soluble resin as a main component on the back side of the support, the protective layer and the back layer are represented by the following general formula (1). By adding a UV-absorbing benzotriazole compound, a heat-sensitive recording material having extremely excellent light resistance can be provided.

(In the formula, R1, R2 and R3 represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cycloalkyl group, etc.) Specific examples of the benzotriazole compound represented by the general formula (11) include, for example. , 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-
(2'-hydroxy-3'-shebutyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-(2'-hydroxy-3').

5'-di-amylphenyl)benzo-l-lyazole, 2-(2'-hydroxy-3',5-di-L-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-7-butyl) -5'-methylphenyl)-5
-chlorobenzotriazole, 2-(2'-hydroxy-3', 5'-di-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-
3',5'-diphenylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'
-methylphenyl)benzotriazole and the like, but of course the present invention is not limited to these.

The above-described benzotriazole compound is used together with a water-soluble resin to form an intermediate layer.

As the leuco dye used in the present invention, those commonly used in this type of heat-sensitive recording material, such as triphenylmethane type, fluoran type, phenothiazine type, auramine type, and spiropyran type, are applicable. ,
As a particularly preferred leuco dye, a fluoran compound represented by the following general formula is used.

(In the formula, R,, R2 are an alkyl group or a cyclohexyl group, R3 is an alkyl group, a haloalkyl group, or a halogen atom, and R4 is a hydrogen atom or an alkyl group. The alkyl group is usually a carbon For example, 3-diethylamino-
7-.

-Chloro-anilinofluorane, 3-diethylamino-
7-m-chloro-anilinofluorane, 3-di-n-butylamino-7-o-chlorophnylinofluorane, 2-
(N-3'-trifluoromethylphenyl)amino-
6-Dinithylaminofluorane, 2-(N-3'-trifluoromethylphenyl-N-methyl)amino-6-
Dinitylaminofluorane, 3-diethylamino-7-
(3'-trifluoromethylphenyl)amino-4'
- Chlorfluorane and the like.

The color developer used in the present invention is a phenol type or sulfur-containing color developer that has been commonly used in the past.

Ester-based, carboxylic acid-based, gold salt-based, amine-based, and other commonly used color developers for this type of heat-sensitive recording material are applicable, but as a particularly preferred color developer, phenylthiourea represented by the following general formula is used. compounds are preferably used.

Specific examples of such phenylthiourea derivatives (in the formula, x and ■ are halogen, alkyl group, or haloalkyl group, and m and n are integers of θ to 3) include: 1 For example, diphenylthiourea, 4.4'-diethylphenylthiourea, 4.4'-dibutylphenylthiourea,
Examples include 4,4'-dichlorophenylthiourea, 3,3'-dichlorophenylthiourea, 3,3'-dimethylphenylthiourea, 3,3'-ditrichloromethylphenylthiourea, and of course, these It is not limited to.

The heat-sensitive coloring layer may contain a binder, a filler, a surfactant, a lubricant, and the like. In this case, binders include water-soluble resins such as polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, imbutylene/maleic anhydride copolymer alkali salts, as well as polyurethane, styrene/butadiene copolymers, polyacrylic esters, etc. latex can be used. In addition, as a filler,
In addition to inorganic substances such as calcium carbonate, silica, titanium oxide, aluminum hydroxide, clay, and talc, inorganic substances such as urea-formalin resin, titanium, aluminum hydroxide, clay, and talc, fine particles of urea-formalin resin, polystyrene, etc. Organic fillers can be used. As the lubricant, in addition to higher fatty acids or their esters, amides, and metal salts, various wax-like substances can be used.

In addition to polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, isobutylene/maleic anhydride copolymer alkali salt, etc., water-soluble resins used in the undercoat layer, protective layer, or backcoat layer include polyurethane, styrene/butadiene copolymer, polyester, etc. Latex such as acrylic ester can be used. Also,
As fillers, in addition to inorganic substances such as calcium carbonate, silica, titanium oxide, aluminum hydroxide, clay, and talc, organic fillers made of fine particles of urea-formalin resin, polystyrene, etc. can be used. As other lubricants, higher fatty acids or their esters, amides, metal salts, etc. can be used, and surfactants and the like can be included as appropriate.

To make the heat-sensitive recording material of the present invention, an aqueous solution containing a water-soluble resin, a filler, and a benzotriazole ultraviolet absorber as main components is coated on a support such as paper 1 synthetic paper, and dried. A coating layer is provided, and an aqueous solution containing a leuco dye, a color developer, and a binder as main components is applied thereon and dried to provide a heat-sensitive coloring layer.

Furthermore, an aqueous solution containing a water-soluble resin, a filler, and a benzotriazole-based ultraviolet absorber as main components is applied thereon and dried to form an aI retaining layer. Here, the amounts of the water-soluble resin, filler, and benzotriazole-based ultraviolet absorber used in the undercoat layer solution are 10 to 30% by weight, 50 to 80% by weight, and 5% to 50% by weight, respectively.
~30% by weight is suitable.

The appropriate amount of the undercoat layer to be formed is 1 to 10 g/proof. The amounts of 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.
Weight % is appropriate. The amount of the protective layer formed is 1~
It is about 10g1rd.

In addition, in order to produce the heat-sensitive recording material of the second invention of the present invention, an aqueous solution containing a leuco dye, a color developer, and a binder as main components is coated on a support such as paper or synthetic paper and dried to develop heat-sensitive coloring. Provide layers. Furthermore, an aqueous solution containing a water-soluble resin, a filler, and a benzotriazole ultraviolet absorber as main components is applied thereon and dried to form a protective layer. Further, an aqueous solution containing a water-soluble resin and a benzotriazole ultraviolet absorber as main components is applied to the back surface of the support and dried to form a back coat layer.

Here, the amount of leuco dye, color developer, and binder used is 5% each.
-30% by weight, 40-80% by weight, 2-20% by weight are suitable. The binding amount of the thermosensitive coloring layer to be formed is 2 to 10
Approximately g/rrr is appropriate. Moreover, the amount of adhesion used for forming the protective layer is suitably about 2 to log/rf.

The appropriate amounts of the water-soluble resin, filler, and benzotriazole ultraviolet absorber used to form the protective layer are 10 to 30% by weight, 50 to 80% by weight, and 5 to 30% by weight, respectively. A suitable amount of the protective layer to be formed is about 1 to 10 g/I.

Also, what are the amounts of the aqueous resin and benzotriazole ultraviolet absorber used to form the back coat layer?

Appropriate amounts are 10 to 30% by weight and 5 to 30% by weight, respectively.

〔effect〕

The heat-sensitive recording material of the first aspect of the present invention contains a benzotriazole ultraviolet absorber represented by the general formula (1) in the underknee 1 layer and the protective layer mainly composed of a water-soluble resin and a filler, By sandwiching a heat-sensitive coloring layer containing leuco dye and color developer as main components between ultraviolet absorber-containing layers, this heat-sensitive recording has extremely excellent light resistance without causing fogging or deterioration of color development in the heat-sensitive coloring layer. materials can be obtained.

Also, 2'9 of the present invention. Ming's heat-sensitive recording material contains a benzotriazole ultraviolet absorber represented by the general formula (1) in the protective layer and back coat layer, and contains a leuco dye and a color developer mainly in the ultraviolet absorber-containing layer. By sandwiching the heat-sensitive color forming layer as a component, it is possible to obtain a heat-sensitive recording material having extremely excellent light resistance without causing fogging or deterioration of color development in the heat-sensitive color forming layer, and without discoloring the back side of the support. .

In the first and second inventions, the effects can be further significantly enhanced by using a combination of a specific leuco dye and a color developer. The heat-sensitive recording material of the present invention is
Utilizing such characteristics, it can be advantageously applied to tags, CAD, labels, etc., which require high light resistance.

〔Example〕

Examples of the present invention are shown below. Note that all parts and percentages shown below are based on weight iq. In addition, each liquid was pulverized and dispersed using a ball mill so that the average particle size of the particles contained was 5 μm or less.

[A liquid]

Leuco dye (3-di-n-butylamino-7-〇-chloroanilinofluorane) 10 parts polyvinyl alcohol 1
O% aqueous solution 10 parts water
30 parts [Liquid B] Color developer (3,3'-dichlorophenylthiourea) 3.5 parts Calcium carbonate 4.0 parts Polyvidyl alcohol 10% aqueous solution 5.5 parts Water
17.0 copies [
Solution C] Thermofusible substance (octadecylcarbamoylbenzene) 10 parts Polyvinyl alcohol 10% aqueous solution 10 parts Water
30
Part [Liquid D] Benzotriazole ultraviolet absorber (2(2'-5'-methylphenyl)benzotriazole 310 parts Polyvinyl alcohol 10%
Aqueous solution 10 parts water
30 parts [Liquid E] Styrene filler 8 parts polyvinyl alcohol 3 parts water
10 parts
F Solution] Polyvinyl alcohol 10% aqueous solution 100 parts Silica 5 parts Lubricant
1 part water
54 copies [G
Liquid] 10% polyvinyl alcohol aqueous solution 100 parts silica 1 part water
59 parts Example 1 [Liquid E] and [Liquid D] obtained as above were uniformly stirred and mixed in a ratio of 4 parts to 1 part, and the weight per tsubo was 50 g/rr. The dry adhesion amount on high-quality paper is 5g/n? It was applied and dried to form an undercoat layer.

Next, the required amounts of [Liquid A], [Liquid B], and (Liquid C) are measured, stirred and mixed uniformly, and coated on the undercoat layer with a dye standard of 0.
5g/rr? 6 Next, [liquid G] and [liquid D] were uniformly stirred and mixed in a ratio of 3 parts to 1 part, and dried on the heat-sensitive coloring layer as described in step 11. Post adhesion amount is 4g
The sample of Example 1 was prepared by coating and drying the coating so as to provide a protective layer.

Example 2 In Example 1, the leuco dye in [Liquid A] was changed to 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-
A sample of Example 2 was prepared in the same manner except that anilifluorane was used and bisphenol A was used as the color developer of [Liquid B].

Example 3 Weigh out the required amount of the above [Liquid A] (Liquid N) (Liquid C), stir and mix uniformly, and dry it on the support so that it is 0.5 g/rrF based on the dye!! 2! Then, a thermosensitive coloring layer was formed.

Next, [Liquid F] and [Liquid D] were uniformly stirred and mixed in a ratio of 3 parts to 1 part, and the coating amount after drying was 48/r on the heat-sensitive coloring layer.
It was coated and dried to form a protective layer.

Furthermore, [liquid G] and [liquid D] were uniformly stirred and mixed in a ratio of 3 parts to 1 part on the back of the support, and the mixture was coated and dried so that the coating amount was 2 g/a after drying, and a back coat layer was formed. A sample of Example 3 was prepared.

Example 4 In Example 3, the leuco dye in [Liquid A] was converted to 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-
A sample of Example 4 was prepared in the same manner except that anilifluorane was used and bisphenol A was used as the color developer of [Liquid B].

Comparative Example 1 A sample of Comparative Example 1 was prepared in the same manner as in Example 1, except that only [liquid E] was provided, that is, an undercoat layer containing no benzotriazole ultraviolet absorber was provided.

Comparative Example 2 A sample of Comparative Example 2 was prepared in the same manner as in Example 1, except that only [liquid G] was provided, that is, a protective layer containing no benzotriazole ultraviolet absorber was provided.

Comparative Example 3 In Example 1, an undercoat layer containing only [Liquid E],
A sample of Comparative Example 3 was prepared in the same manner except that a protective layer containing only [liquid G] was provided.

Comparative Example 4 In Example 3, only [Liquid F], that is, benzo 1-
A sample of Comparative Example 4 was prepared in the same manner except that a protective layer containing no lyazole ultraviolet absorber was provided.

Comparative Example 5 A sample of Comparative Example 5 was prepared in the same manner as in Example 3, except that only [liquid G] was provided, that is, a back coat layer containing no benzotriazole ultraviolet absorber was provided.

Comparative Example 6 In Example 3, a protective layer containing only [Liquid F] and [Liquid G]
A sample of Comparative Example 6 was prepared in the same manner except that one layer of Barafco-1 was provided.

Next, the following tests were conducted on each of the heat-sensitive recording materials obtained above, and the results are shown in Table 1.

Coloring property: Using a printing simulator manufactured by Matsushita Electronic Components ■, the coloring area is measured with a Macbeth densitometer when coloring is caused by thermal energy of 0.85 mJ, and the value is calculated as Dmax.
It was shown as In addition, the density of the skin area in this case is Dmin
It was shown in

Lightfastness: The colored part and background part colored with a print simulator (0.71 mJ) are exposed to 20+1 sunlight for 1 day,
Furthermore, after the back side was exposed to sunlight for 5011 hours, changes in density in the image area and the background area were measured using a Macbeth densitometer. Further, for Examples 3 to 4 and Comparative Examples 4 to 6, the state of discoloration on the back surface of the support was compared.

As can be seen from the above results, the product of the present invention has extremely excellent light resistance, and is even more effective when combined with specific leuco dyes and color developers.

Claims (4)

[Claims] (1) An undercoat layer containing a water-soluble resin and filler as main components is provided on the support, a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on the undercoat layer, and a water-soluble A thermosensitive recording material provided with a protective layer mainly composed of a resin and a filler, characterized in that the undercoat layer and the protective layer contain an ultraviolet absorbing benzotriazole compound represented by the following general formula. Recording materials. General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, and R_3 represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cycloalkyl group, etc.) (2) Leuco dyes have a general formula ▲ mathematical formula, chemical formula, table, etc. or an alkyl group), and the color developer has a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (wherein, X and Y are a halogen atom, an alkyl group, or a haloalkyl group, The heat-sensitive recording material according to claim 1, which is a phenylthiourea compound represented by the following formula (m and n are integers of 0 to 3). (3) A thermosensitive color forming layer containing a leuco dye and a color developer is provided on the support, and a protective layer containing a water-soluble resin and a filler as main components is provided on the support, and on the back of the support, A heat-sensitive recording material provided with a back coat layer mainly composed of a water-soluble resin, characterized in that the protective layer and the back coat layer contain an ultraviolet absorbing benzotriazole compound represented by the following general formula. Heat-sensitive recording material. General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, and R_3 represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cycloalkyl group, etc.) (4) Leuco dyes have a general formula ▲ mathematical formula, chemical formula, table, etc. or an alkyl group), and the color developer has a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (wherein, X and Y are a halogen atom, an alkyl group, or a haloalkyl group, 4. The heat-sensitive recording material according to claim 3, which is a phenylthiourea compound represented by the following (m and n are integers of 0 to 3).