JPS6259081A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material capable of forming a color in high density with low energy and having high oil resistance, high water delamination resistance, high reliability of recorded images and an excellent head matching property, by providing a thermal color forming layer comprising a leuco due and a color developer on a base, and providing thereon an overcoat layer comprising a binder and aluminum hydroxide as a filler. CONSTITUTION:The binder is used in an amount of 20-70wt% while aluminum hydroxide is used in an amount of 5-50wt% in an overcoat layer, and the dry-basis coating amount of the layer is set to be 1.0-6.0g/m<2>, whereby favorable results can be obtained. The overcoat layer functions to reduce lowering of color forming sensitivity, enhance oil resistance, water resistance and reliability of printed images and ensure a favorable head matching property.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material with improved thermal sensitivity and head matching properties.

[Prior art]

Demand for heat-sensitive recording materials is rapidly expanding as they are inexpensive and easy to maintain for recording machines.

However, recently, as the speed of facsimiles, printers, barcode labels, etc. has increased, it has become possible to record high-density, clear images even with a small amount of energy. eraser,
No discoloration or color development due to plasticizers contained in mending tape, PVC, etc., alcohol such as whiskey, sake, shochu, etc., or water, and head matching properties, such as no sticking, head dregs, or head wear. Such quality is required.

In order to achieve high sensitivity, it is of course important to select the coloring material used, but the amount of fillers, binders, etc. used in combination is also important.

It is necessary to minimize its use in the heat-sensitive coloring layer. However, as these decrease, the reliability of the image decreases.

Head matching performance deteriorates. In particular, there are problems such as decolorization of images due to oils and fats and plasticizers, and peeling and sticking of layers due to water and alcoholic beverages. In order to improve this drawback, it has been proposed to provide various overcoat layers on the heat-sensitive coloring layer. Since the thermal head comes into contact with the thermal head through the lens, there is a drawback that heat conduction is inhibited and coloring sensitivity is reduced.

Furthermore, in the conventionally known method of providing an overcoat layer,
In order to prevent oils and plasticizers from penetrating into the heat-sensitive coloring layer, it is necessary to increase the ratio of binder and filler.
As a result, sticking does not occur easily, and in order to prevent this sticking, fillers have been used in conventional methods, but depending on the type of filler, head wear may occur, and high temperature processing cannot be performed, so binders are used. The disadvantage is that it takes a long time for the adhesive to harden and improve the sticking problem.

〔the purpose〕

The present invention provides a heat-sensitive recording material that does not have the above-mentioned disadvantages, develops color at high density with low energy, has high oil resistance, water peeling resistance, and reliability of recorded images, and has excellent head matching properties. The purpose is to provide materials.

〔composition〕

According to the present invention, in a heat-sensitive recording material in which a heat-sensitive color forming layer containing a leuco dye and a color developer is provided on a support, and an overcoat layer is provided thereon, a binding layer is formed in the overcoat layer. Provided is a heat-sensitive recording material characterized in that it contains aluminum hydroxide as an agent and a filler. □ That is, in the present invention, an overcoat layer using aluminum hydroxide as a main component and a binder as a filler is provided on the heat-sensitive coloring layer, thereby maintaining high sensitivity and improving oil resistance, water resistance, and image resistance. It is characterized by improved reliability and head matching performance.

The overcoat layer of the present invention has little decrease in color development sensitivity,
It functions as a layer that improves oil resistance, water resistance, and reliability of printed images, and also improves head matching properties.

In the present invention, binders used in the overcoat layer include polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyethylcellulose,
Cellulose derivatives such as carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride Acid copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide,
Water-soluble polymers such as sodium alginate, gelatin, and casein are preferred, and if necessary, 1, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer It is also possible to use a water-resistant agent such as a latex or a water-soluble polymer such as polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer.

The amount of the overcoat layer constituents used is 20 to 70% by weight for the binder and 5% by weight for the aluminum hydroxide.
Favorable results are obtained by using an amount of 1.0 to 50% by weight, preferably 10 to 30% by weight, and a dry coating weight of the overcoat layer of 1.0 to 6.0 g/'m.

If the amount of binder used is less than 20% by weight and the amount of aluminum hydroxide is more than 50% by weight, the prevention of penetration by oils, fats, plasticizers, etc. will be insufficient, and the amount of binder used will be more than 70% by weight. Furthermore, if the aluminum hydroxide content is less than 5% by weight, it is not preferable because it takes a long time to function as an overcoat layer.

The thermosensitive color forming layer of the present invention mainly contains leuco dye and color developer.
It is one component, and the leuco dye is used alone or in combination with two components.
These leuco dyes can be applied in a mixture of more than one species, and any of the leuco dyes that have been applied to this type of heat-sensitive material can be used, such as triphenylmethane, fluoran, phenothiazine, auramine, etc. Specific examples of leuco dyes that are preferably used include leuco compounds of dyes such as , spiropyran, indolinophthalide, etc., as 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-dimethyl aminophenyl)-6-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorphthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorfur orane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane.

3-diethylamino-6-methyl-7'-chlorofluoran.

3-(N-p-tolyl-N-dithylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'- trifluoromethylphenyl)amino)-6-dinithylaminofluorane, 2-(3,
6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam).

3-diethylamino-6-methyl-7-(a+-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)fluoran, 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-(o-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)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

In addition, as the color developer used in the present invention, various electron-accepting substances that react with the above-mentioned color dye and develop color when heated are used, and specific examples thereof include the following: Examples include phenolic substances, organic or inorganic acidic substances, and esters and salts thereof.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-Cyclohexylsalicylic acid, 3,5-ter
t-Butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis (2,6-
dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4,4'-isopropylidene bis(2-methylphenol), 4,4'-
Isopropylidene bis(2,6-dimethylphenol)
, 4,4'-isopropylidene bis(2-tert-butylphenol), 4,4'-5ec-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2- methylphenol), 4-tart-butylphenol, 4
-Phenylphenol, 4-hydroxydiphenoxide, 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-tert-octylcatechol, 2.2'-
Methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6tert-butylphenol).

2.2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, P-
Butyl hydroxybenzoate, benzyl p-hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, p-
p-methylbenzyl hydroxybenzoate, n-octyl p-hydroxybenzoate, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-6-naphthoic acid Zinc acid, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, zinc 2-hydroxy-ρ-toluate, tin 3,5-di-tert-butylsalicylate ,
tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid,
Stearic acid, 4-hydroxyphthalic acid, boric acid, etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyl, etc. Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/ Maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt,
In addition to water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, and Latex such as butyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

Further, in the thermosensitive coloring layer of the present invention, the leuco dye,
In addition to color developers and fillers, auxiliary additives commonly used in this type of heat-sensitive recording materials, such as, for example.

A surfactant, a thermofusible substance (or lubricant), etc. can be used in combination. In this case, the thermofusible substances include, for example, higher fatty acids or their esters, amides, or metal salts, various waxes, clamps of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, etc. , 3,4-epoxy-dialkyl hexahydrophthalate, higher ketones, other thermofusible organic compounds, etc.
Examples include those having a melting point of about ~200°C.

The heat-sensitive recording material of the present invention can be produced by a generally known method. For example, first, the leuco dye and the color developer are separated, and then the polyvinyl alcohol and the color developer are separated.
Along with aqueous solutions of water-soluble polymers such as hydroxyethyl cellulose, methyl cellulose, alkali salts of styrene-maleic anhydride copolymers, and starch, ball mills and attritors.

After pulverizing and dispersing with a dispersing machine such as a sand mill until the dispersed particle size becomes 1 to 3μ, fillers, thermofusible material dispersions, antifoaming agents, etc. are added to a certain formulation as necessary to form a thermosensitive coloring layer. Prepare coating solution. Furthermore, the overcoat liquid is prepared by mixing or dispersing a binder, aluminum hydroxide, etc.Next, these coating liquids are sequentially applied and laminated on a support such as paper or synthetic paper. Creating an inventive heat-sensitive recording material.

〔effect〕

Because the heat-sensitive recording material of the present invention is provided with an overcoat layer containing a binder and aluminum hydroxide, it exhibits less deterioration in single-color development sensitivity, high oil resistance, water resistance, and image reliability; It is a heat-sensitive recording material with excellent tinging properties.

〔Example〕

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 Liquids (A) and (B) were prepared by pulverizing and dispersing mixtures having the following formulations using a ball mill and an attritor to give a volume average diameter of approximately 1.5 μm.

(A) Liquid 3-(N-cyclohexyl-N-methyl)amino-6-
Methyl-7-7nylinofluorane
20 parts by weight 10% polyvinyl alcohol aqueous solution 16 water
64 (B) Liquid benzyl p-oxybenzoate 10 parts by weight Calcium carbonate 10 parts by weight 10% polyvinyl alcohol aqueous solution 16 Water
54 Next, (A) liquid:
[B] The two were mixed and stirred at a weight ratio of 1:4 to obtain a heat-sensitive coloring layer coating solution.

Further, a mixture consisting of the following formulation was dispersed using a sand mill to obtain an overcoat layer coating solution.

Aluminum hydroxide 20 parts by weight Itaconic acid modified polyvinyl alcohol alkali salt 10% aqueous solution 40 Zinc stearate 10 N polyamide epichlorohydrin resin 10 Water
20〃Next, apply these coating liquids to 5
The dry adhesion amount on commercially available high-quality paper of 0g/rd is Δ, 0fi for the heat-sensitive coloring layer, and 3 for the overcoat layer.
．． Each was coated and dried to a concentration of 0 g/%, and then laminated to produce a heat-sensitive recording material of the present invention.

Example 2 (Liquid C) Bisphenol A 10 parts by weight Parabenzyldiphenyl 10 n Calcium carbonate 10 I! 10% polyvinyl alcohol aqueous solution 20 Water
50 I! is prepared in the same manner as Solution B in Example 1. Then (A) liquid: (C) liquid = 1:4
A heat-sensitive recording material of the present invention was prepared in the same manner as in Example 1 by mixing and stirring the two at a weight ratio of .

Comparative Examples 1 and 2 Comparative heat-sensitive recording materials were prepared in the same manner as in Examples 1 and 2 except that the overcoat layer was not provided.

Comparative Example 3 A heat-sensitive recording material of a comparative example was prepared in the same manner as in Example 1 except that calcium carbonate was used instead of aluminum hydroxide in the overcoat layer of Example 1.

Comparative Example 4 A heat-sensitive recording material of a comparative example was prepared in the same manner as in Example 1 except that silica was used instead of aluminum hydroxide in the overcoat layer of Example 1.

The above heat-sensitive recording materials are calendered to a Beck smoothness of 700 to 1000 seconds after being left at room temperature for 48 hours to determine dynamic color development sensitivity, image fading resistance, image whitening, oil resistance, water resistance, and sticking. A test was conducted. The results are shown in Table 16.The test method was performed as follows.

(1) Dynamic color development sensitivity: head power 0.451 using a thermal printing experimental device with a thin film head manufactured by Matsushita Electronics Parts ■
1/dot, 1 line recording time 2Orss/Q.

Print with a pulse width of 0.8.1.2.1.6.2.0 m5ec under the conditions of a scanning line density of 8 x 3.85 dots/mm,
The print density was measured using a Macbeth densitometer RD-514.

(2) Image fading rate...For the samples whose dynamic color development sensitivity was measured in (1), those with a print density of 1.0 to 1.2 (this is Do) were left at room temperature for 15 days. The subsequent concentration will be measured and will be referred to as D).

The image fading rate was determined in accordance with the following.

(3) Image whitening... Perform the same test as (2),
Judgment was made by visual inspection as follows.

0: Almost no white powder generation Δ: White powder generation, but no practical problem
The experiment was carried out in the same manner as in (2) except that the following was applied.

0: Image fading rate less than 30% Δ: Image color rate 30 to 50% ×: Image fading rate 50% or more (5) Water peeling resistance: Immerse the printed sample in water for 24 hours and check whether or not the layer peels off. The following tests were conducted and the results were determined as follows.

0: No layer peeling ×: Layer peeling (6) Sticking: Using the printing device used for dynamic coloring sensitivity, head power 0.61/dot.

The pulse width was changed to 2.9 ms, and a test for the presence or absence of sticking was conducted, and the judgment was made as follows.

0: No sticking ×: Sticking Table-1

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on a support, and an overcoat layer is provided thereon, the overcoat layer contains a binder, A heat-sensitive recording material characterized by containing aluminum hydroxide as a filler.