JP2000015932A - Thermal recording material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material having superior water resistance and anti-solvent property, and being hard-to-color or the like even when allowed to stand at a high temperature and high humidity atmosphere for a long period of time. SOLUTION: A cross-linking combination layer consisting of one kind or more selected from copolymeric saponified matter of diacetoneacrylamide-fatty acid vinylester, a hydrazine compound, and a diamine compound is included in an interlayer between a support basement and a thermal coloring component layer in thermal recording material with a thermal coloring component layer set on the support basement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording material suitable for POS labels, thermosensitive magnetic paper sheets and the like.

[0002]

2. Description of the Related Art Thermal recording materials include recording paper and recording sheets such as facsimile machines, computer terminals, measuring printers, medical measuring printers, and POS.
Widely used for applications such as labels. As a method for producing this heat-sensitive recording material, a method is known in which a colorless or pale-color lactone compound such as crystal violet lactone and an acidic compound such as a phenol compound are coated on a support together with a water-soluble binder. I have. Examples of the water-soluble binder include polyvinyl alcohol (hereinafter abbreviated as PVA), methyl cellulose,
Carboxymethylcellulose, polyacrylic acid, starch, and the like are used. Among them, PVA is widely used because of its excellent adhesive performance.

However, in a thermal recording material manufactured using a conventional water-soluble binder, a color image formed by the compatibility and reaction of a color-forming lactone compound and an acidic compound is unstable to moisture or an organic solvent. However, there is a drawback that the colored portion is easily discolored or disappears due to contact with water or a plasticizer in a synthetic resin used for wrapping or the like.

As a method for overcoming such disadvantages, Japanese Patent Publication No. 58-33117 discloses a method in which PVA is used as a water-soluble binder and a water-resistant agent such as an aldehyde compound or a metal salt is reacted. However, in this method, in order to make PVA sufficiently water resistant, 100 ° C.
Since it is necessary to promote the crosslinking reaction by adding the above-mentioned heat treatment or an acidic substance, there is a problem that coloration occurs due to compatibility and reaction between the chromogenic lactone compound and the acidic compound during the treatment. In addition, there is a problem that water resistance and solvent resistance under pretreatment conditions under which the heat-sensitive coloring agent does not develop a color even with a system of another crosslinking agent or modified PVA and a crosslinking agent are low.

[0005]

On the other hand, the present inventors have proposed a method for making a PVA-based resin water-resistant by reacting a hydrazine with a PVA-based resin containing a diacetone group (JP-A-8-151).
No. 412) and a paper coating agent comprising a resin composition further containing an amine compound (Japanese Patent Application No. 8-26657).
No. 7), and by using these methods as a binder for a heat-sensitive coloring component layer of a heat-sensitive recording material, water resistance and solvent resistance are improved. It does not satisfy the demands for higher functionality of the heat-sensitive recording material accompanying such as, especially high water resistance,
There has been a demand for a heat-sensitive recording material that is more excellent in water resistance and solvent resistance, such as a POS label or a heat-sensitive magnetic cardboard that requires solvent resistance.

An object of the present invention is to provide a heat-sensitive recording material which does not require severe heat treatment and has better water resistance, solvent resistance and color development than conventional heat-sensitive recording materials.

[0007]

According to the present invention, there is provided a thermosensitive recording material having a thermosensitive coloring component layer provided on a supporting substrate, wherein an interlayer between the supporting base and the thermosensitive coloring component layer is provided. And a thermosensitive color-forming component layer having a cross-linking layer comprising (A) a saponified diacetone acrylamide-fatty acid vinyl ester copolymer and (B) one or more selected from hydrazine-based compounds and diamine-based compounds. A thermosensitive recording material, and (A) a saponified product of diacetone acrylamide-fatty acid vinyl ester copolymer and (B) a hydrazine-based compound on a support substrate.
An undercoat layer comprising at least one selected from diamine compounds is formed and dried, and a heat-sensitive coloring component layer is formed thereon. Then, a copolymer of (A) diacetone acrylamide-fatty acid vinyl ester is formed thereon. A method for producing a thermosensitive recording material, comprising forming a top coat layer comprising a combined saponified product and (B) one or more selected from hydrazine-based compounds and diamine-based compounds, followed by drying.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The heat-sensitive recording material of the present invention is a heat-sensitive recording material provided with a heat-sensitive coloring component layer that develops a color by heat at the time of printing on a supporting substrate, and includes an interlayer between the supporting substrate and the heat-sensitive coloring component layer and a heat-sensitive coloring. On the component layer, there is provided a cross-linking layer comprising (A) a saponified product of diacetone acrylamide-fatty acid vinyl ester copolymer and (B) one or more selected from hydrazine-based compounds and diamine-based compounds. .

As the support substrate used in the heat-sensitive recording material of the present invention, paper such as high quality paper, medium paper, coated paper, synthetic paper, cloth, wood, metal plate, or polyester, polyamide, polystyrene, polychlorinated Examples include, but are not limited to, plastic films and sheets such as vinyl, polymethyl methacrylate, cellulose acetate, polycarbonate, and polyimide, film-laminated paper, and woven fabric sheets.

As the thermosensitive coloring component used in the thermosensitive recording material of the present invention, two components of a coloring material and a developing material which reacts with the coloring material when heated (at the time of printing) to form a color are representative. No. As the coloring substance among the thermosensitive coloring components, a coloring lactone compound is a typical example. The color-forming lactone compound may be any compound that can form a color by reacting with an acidic compound when heated, and includes, for example, various compounds such as triphenylmethane, triphenylmethanephthalide, fluoran, leuco auramine, and spiropyran. Leuco compounds.

The color developing substance of the thermosensitive coloring component may be an acidic compound having a property of liquefying or vaporizing at 70 ° C. or higher and reacting with the leuco compound to form a color. , 2-bis (4-oxyphenyl) propane (also known as bisphenol A), 4-phenylphenol, 4-hydroxyacetophenone,
2'-diacetoxyphenyl, 2,2'-methylenebis (4-chlorophenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4 '
-Isopropylidenebis (2-chlorophenol),
4,4'-isopropylidenebis (2-methylphenol), 4,4'-sec-butylidenephenol, 4,
Phenolic compounds such as 4'-ethylenediphenol and 4,4'-ethylenebis (2-methylphenol) are exemplified.

The saponified product of (A) diacetone acrylamide-fatty acid vinyl ester copolymer (hereinafter abbreviated as DAVES) used in the present invention is obtained by copolymerizing fatty acid vinyl ester and diacetone acrylamide. It can be produced by a known method such as saponification of a polymer.

Examples of the fatty acid vinyl ester used in the above copolymerization include vinyl formate, vinyl acetate, vinyl propionate, and vinyl pivalate. Of these, vinyl acetate is industrially preferred.

As the above-mentioned copolymerization method of the fatty acid vinyl ester and diacetone acrylamide, conventionally known various methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization can be employed, and among them, methanol is used as a solvent. Solution polymerization is industrially preferred. As a method for saponifying a polymer obtained by copolymerizing a fatty acid vinyl ester and diacetone acrylamide, conventionally known alkali saponification and acid saponification can be applied. Industrially preferred is a method in which an alkali hydroxide is added to a mixed solution of water, methyl acetate, benzene and the like to carry out alcoholysis.

The DAVES used in the present invention is an unsaturated monocarboxylic acid such as crotonic acid, acrylic acid, methacrylic acid and the like, which can be copolymerized with a fatty acid vinyl ester or diacetone acrylamide as long as the effects of the present invention are not impaired. Acids and their esters, salts, anhydrides, amides,
Nitriles, maleic acid, itaconic acid, unsaturated dicarboxylic acids such as fumaric acid and salts thereof, unsaturated dibasic acid monoalkyl esters such as monomethyl maleate and monomethyl itaconate, α-olefins having 2 to 30 carbon atoms ,
It may be copolymerized with alkyl vinyl ethers and vinyl pyrrolidone. In addition, the obtained D
AVES may be post-modified by a reaction such as acetalization, urethanization, etherification, grafting, phosphoric esterification, acetoacetylation or the like as long as the effects of the present invention are not impaired.

The content of diacetone acrylamide units in DAVES used in the present invention is preferably in the range of 0.1 to 15 mol%, more preferably 0.5 to 10 mol%. If the content of the diacetone acrylamide unit is too small, the water resistance and the solvent resistance may be reduced. DAVES is a water-soluble polymer,
If the content is too large, the water solubility may decrease and a problem may occur in workability. In addition, the DA used in the present invention
Although the polymerization degree and the saponification degree of VES are not particularly limited,
4% aqueous solution viscosity at 3 ° C. is 3 mPa. s or more and a degree of saponification of 85 mol% or more are preferable.

The hydrazine compound (B) used in the present invention includes, for example, hydrazine, hydrazine hydrate, monohydrate or salt of hydrazine, phenylhydrazine, methylhydrazine, ethylhydrazine,
Aromatic or aliphatic hydrazines such as n-propylhydrazine, n-butylhydrazine, ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazine and salts thereof, and carbohydrazide Benzoic acid hydrazide, formic acid hydrazide, acetate hydrazide, propionic acid hydrazide, n-butyric acid hydrazide, isobutyric acid hydrazide, n-valeric acid hydrazide, monocarboxylic acid hydrazide such as pivalic acid hydrazide, oxalic acid dihydrazide, and malonone. Dicarboxylic acid dihydrazide such as acid dihydrazide, succinic dihydrazide, glutaric dihydrazide, adipic dihydrazide, sebacic dihydrazide, maleic dihydrazide, fumaric dihydrazide, itaconic dihydrazide, etc. Polymer compounds having a hydrazino group such as azine and N-aminopolyacrylamide, and hydrazine compounds such as adipic acid dihydrazide acetonezone and adipic acid dihydrazide methyl ethyl ketonezone obtained by reacting these hydrazine compounds with acetone and methyl ethyl ketone having a ketone group. Derivatives of compounds and the like can be mentioned.

The (B) diamine compound includes
Ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,2-diaminopropane, 1,3-
Examples thereof include diaminopropane, 1,4-diaminobutane, and aminoethylated copolymer, and the hydrazine compound has a high effect in terms of water resistance and is preferred. These compounds can be used alone or in combination of two or more.

The water-proofing agent (B) used in the present invention
The amount of (one or more selected from hydrazine-based compounds and diamine-based compounds) is preferably 0.5 to 50 parts by weight, more preferably 1 to 100 parts by weight of DAVES.
It is selected from the range of 30 to 30 parts by weight. If the amount is less than 0.5 part by weight, the water resistance tends to be insufficient. If the amount is more than 50 parts by weight, the viscosity stability of the aqueous solution is poor and the viscosity may increase over time, which is not preferable.

The DAVES used in the present invention and the above-mentioned waterproofing agent can be used alone.
If necessary, other water-soluble resins, water-dispersible resins, inorganic fillers, waxes, melting point regulators, surfactants, plasticizers,
A pH adjuster or the like can be used in combination.

Other water-soluble or water-dispersible resins that can be used in combination are albumin, gelatin, casein,
Cellulose derivatives such as starch, gum arabic, methylcellulose, hydroxyethylcellulose, polyamide resins, melamine resins, PVA, vinylpyrrolidone-modified P
VA, N-substituted or unsubstituted (meth) acrylamide-modified PVA, poly (sodium (meth) acrylate), anion-modified PVA, sodium alginate, anionic water-soluble resin such as water-soluble polyester, polyethyleneimine, polyvinylamine, polyallylamine, A polyallylamine sulfone copolymer or an ammonium salt thereof, a cationized starch, a cationized poly (meth) acrylamide, a cation-modified PVA, a cationic water-soluble resin such as a cationized polyamide resin, an SBR latex,
Water-dispersible resins such as NBR latex, vinyl acetate resin emulsion, ethylene / vinyl acetate copolymer emulsion, (meth) acryl ester resin emulsion, and vinyl chloride resin emulsion.

These water-soluble or water-dispersible resins are
DAVES and a hydrazine compound used in the present invention,
When used in combination with one or more selected from diamine-based compounds, the ratio is at most 500 parts by weight, preferably at most 300 parts by weight, per 100 parts by weight of DAVES.

Inorganic fillers that can be used in the present invention include silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina, zinc oxide, and satin white. In this case, the ratio (DAVES / filler) is usually 1/100 to 100/1,
Preferably it is selected from the range of 5/100 to 100/5.

The method for producing the thermosensitive recording material of the present invention will be described below by taking as an example the case where a chromogenic lactone compound and a phenol compound are used as thermosensitive coloring components. An aqueous solution comprising DAVES and at least one selected from hydrazine-based compounds and diamine-based compounds is applied to a support substrate in advance and dried to form an undercoat layer. The color-forming lactone compound and the phenol compound are separately pulverized and atomized, and if necessary, an inorganic filler, waxes, a melting point modifier, a surfactant, etc. are added, and if necessary, DAVES and a hydrazine-based compound are further added. A heat-sensitive coating liquid is prepared by adding a composition comprising at least one selected from diamine-based compounds, or another water-soluble resin, and the resultant is coated on an undercoat layer and dried to form a heat-sensitive coloring component layer. Thereafter, an aqueous solution containing DAVES and at least one selected from hydrazine-based compounds and diamine-based compounds is applied on the thermosensitive coloring component layer and dried to form a top coat layer. DAVES and one or more selected from hydrazine-based compounds and diamine-based compounds form a crosslink during drying.

In the above method, one or more selected from hydrazine-based compounds and diamine-based compounds are added to the heat-sensitive coating solution to form a heat-sensitive coloring component layer. Post-reaction can also be performed on the heat-sensitive recording material during drying.

The use amount of DAVES and one or more selected from hydrazine-based compounds and diamine-based compounds as the undercoat layer and the topcoat layer of the heat-sensitive recording material of the present invention is not particularly limited. The coating amount as a minute is preferably 0.5 to 5 g / m ² ,
As a coating method, a mixed aqueous solution of the above composition is impregnated into a supporting substrate by a normal pressing method such as a size press, an air knife coater, a roll coater, a bar coater, and a blade coater, or the upper surface of the supporting substrate and A method such as forming a coat layer on both surfaces with the lower surface can be used, and after separately applying an aqueous solution of DAVES and one or more aqueous solutions selected from hydrazine-based compounds and diamine-based compounds, A method of reacting on a supporting substrate may be used.

When a mixed aqueous solution of DAVES and at least one selected from hydrazine-based compounds and diamine-based compounds is prepared in advance and applied on the thermosensitive coloring layer, they react during the application to increase the viscosity. To prevent
Water-soluble organic amines can be added. Examples of the water-soluble organic amine used herein include primary alkanolamines such as monoethanolamine, aminoethylethanolamine and monoisopropanolamine, primary alkylamines such as methylamine, ethylamine and n-propylamine, and alanine. And aminocarboxylic acids such as glycine and ammonia.

The heat-sensitive recording material of the present invention can be used as a recording paper for facsimile machines, computer terminals, measuring printers, POS labels, and the like. Affixed as a product label, address label, and the like, and also provided on the back of the support with a magnetic recording layer mainly composed of a ferromagnetic material and a binder, useful for a ticket, a commuter pass, etc. It can be used as a heat-sensitive recording magnetic paper, and also as a heat-sensitive recording material that can be printed by ultraviolet irradiation by including an ultraviolet-curable colored printing ink in the top coat layer. Not limited to

The heat-sensitive recording material of the present invention is excellent in water resistance, and the reason for having such excellent performance is presumed as follows. The DAVES used in the present invention forms a cross-linking by drying in the presence of at least one selected from hydrazine-based compounds and amine-based compounds without performing heat treatment, pH adjustment, and other pretreatments. By forming such a crosslinked polymer layer between the support base material and the thermosensitive coloring component layer and on the thermosensitive coloring component layer, it prevents water and plasticizer from entering from the outside, thereby providing high water resistance and solvent resistance. Is considered to be obtained.

[0030]

Next, the present invention will be described specifically with reference to examples. In the examples, "%" is used unless otherwise specified.
And "parts" are by weight. The methods for measuring various physical properties in the examples are shown below. (1). Evaluation of Water Resistance The produced heat-sensitive recording material was heated and colored, immersed in water at 40 ° C. for 24 hours, and the degree of elution was evaluated by rubbing the coated surface with a finger. ○: No elution, △: Slight elution, ×: Severe elution (2). Evaluation of solvent resistance The prepared heat-sensitive recording material was colored by heating, and the colored surface was compared with a commercially available soft vinyl chloride resin film. After contacting, applying a load, and allowing to stand in a 45 ° C. constant temperature bath for 2 days, the thigh color by a plasticizer was compared and evaluated visually. ○: no thigh color is observed, Δ: slight thigh color is observed,
×: Intense thigh color (3). Evaluation of coloring property The prepared heat-sensitive recording material was left in a constant temperature / humidity bath at 40 ° C. and 90% RH for 7 days, and the coloring properties before and after the leaving were compared and visually evaluated. . ○: No coloring, ×: Coloring occurred. (4). Overall evaluation: When the required performance as a heat-sensitive recording material is satisfied in all respects of water resistance, solvent resistance and coloring properties, When at least one was not satisfied, it was evaluated as ×.

Example 1 100 parts of a 5% aqueous solution of DAVES (degree of polymerization 1,700, degree of saponification 98.5) containing 6.0 mol% of diacetone acrylamide units and 10% of adipic dihydrazide
An aqueous coating solution was prepared by thoroughly mixing 3 parts of the aqueous solution, coated on a high-quality paper at 2 g / m ² with a bar coater, and dried at 40 ° C. for 3 hours to form an undercoat layer. Next, each of the following components was pulverized using a ball mill for 24 hours to prepare dispersions A and B, and 50 parts of each were mixed well to prepare a heat-sensitive coating liquid.
/ M ² with a bar coater and 24 at 40 ° C.
After drying for 2 hours, the above-mentioned coating solution was applied at 2 g / m ^2.
Was applied with a bar coater and dried at 40 ° C. for 3 hours to form a top coat layer to obtain a thermosensitive recording material. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, excellent performance was exhibited in water resistance, solvent resistance, and color development.

Dispersion A 20% aqueous solution of PVA having a polymerization degree of 1700 and a saponification degree of 98.5 mol% 5.0 parts Crystal violet lactone 1.5 parts Pure water 43.5 parts Dispersion liquid B Polymerization degree 1700, saponification degree 98.5 Molar% PVA 20% aqueous solution 10.0 parts Bisphenol A 6.0 parts Kaolin clay 4.5 parts Stearamide 2.0 parts Pure water 27.5 parts

Example 2 N-type was used instead of adipic dihydrazide used in Example 1.
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that aminopolyacrylamide was used. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. Table 1
As is clear, excellent performance was exhibited in water resistance, solvent resistance, and color development.

Example 3 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that dihydrazide diacetone adipate was used instead of dihydrazide adipic acid used in Example 1. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, excellent performance was exhibited in water resistance, solvent resistance, and color development.

Example 4 The procedure of Example 1 was repeated, except that ethylenediamine was used instead of adipic dihydrazide used in Example 1.
A thermosensitive recording material was obtained. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, excellent performance was exhibited in water resistance, solvent resistance, and color development.

Example 5 DAVES containing 6 mol% of diacetone acrylamide units used in Example 1 (polymerization degree 1700, saponification degree 9)
Heat-sensitive in the same manner as in Example 1 except that DAVES (polymerization degree: 600, saponification degree: 95.0 mol%) containing 3.5 mol% of diacetone acrylamide units was used instead of 8.5 mol%). A recording material was obtained. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, excellent performance was exhibited in water resistance, solvent resistance, and color development.

Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that no adipic dihydrazide was used. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. Table 1
As is clear, the water resistance and the coloring were poor.

Comparative Example 2 DAVES containing 6 mol% of diacetone acrylamide units used in Example 1 (degree of polymerization 1700, degree of saponification 9)
8.5 mol%) instead of polymerization degree 1700 and saponification degree 9
Example 1 except that 8.5 mol% of unmodified PVA was used.
In the same manner as in the above, a thermosensitive recording material was obtained. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, the target performance was not reached in all of the water resistance, the solvent resistance, and the color development.

Comparative Example 3 Adipic acid dihydrazide used in Example 1 was replaced with 40
% Heat-sensitive recording material was obtained in the same manner as in Example 1 except that 3 parts of glyoxal was used. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, the target performance was not reached in all of the water resistance, the solvent resistance, and the color development.

Comparative Example 4 DAVES containing 6 mol% of a diacetone acrylamide unit used in Example 1 (degree of polymerization 1700, degree of saponification 9)
(8.5 mol%), and a heat-sensitive recording material was obtained in the same manner as in Example 1 except that oxidized starch was used. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, the target performance was not reached in all of the water resistance, the solvent resistance, and the color development.

Comparative Example 5 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the thermosensitive coloring layer was formed without forming the undercoat layer and the topcoat layer. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1, the target performance was not reached in all of the water resistance, the solvent resistance, and the color development.

Comparative Example 6 In place of PVA having a polymerization degree of 1700 and a saponification degree of 98.5 mol% as a water-soluble resin used in the dispersions A and B of the heat-sensitive coating liquid, 6 mol% of diacetone acrylamide unit was contained. A thermosensitive recording material was obtained in the same manner as in Comparative Example 5, except that DAVES (degree of polymerization: 1700, degree of saponification: 98.5 mol%) was used. The performance of this heat-sensitive recording material was evaluated, and the results are shown in Table 1. As is clear from Table 1,
Although the coloring property was excellent, the target performance was not reached in terms of water resistance and solvent resistance.

[0043]

[Table 1]

[0044]

As is apparent from the above description, according to the present invention, no severe heat treatment is required, the water resistance and the solvent resistance are excellent, and the color development and the like can be obtained even when left for a long time under high temperature and high humidity. It is possible to provide a heat-sensitive recording material that hardly occurs and is suitable for POS labels, heat-sensitive magnetic ticket paper, and the like.

Claims (2)

[Claims] 1. A thermosensitive recording material having a heat-sensitive coloring component layer provided on a support substrate, wherein (A) diacetone acrylamide-fatty acid vinyl ester is formed between the support substrate and the heat-sensitive coloring component layer and on the heat-sensitive coloring component layer. A thermosensitive recording material comprising a crosslinked layer of a saponified copolymer and at least one selected from the group consisting of a hydrazine compound and a diamine compound (B). 2. A coating liquid comprising (A) a saponified diacetone acrylamide-fatty acid vinyl ester copolymer and (B) one or more selected from hydrazine-based compounds and diamine-based compounds on a supporting substrate. An undercoat layer is formed by coating and drying, and a thermosensitive coloring component layer is formed thereon. Then, (A) a saponified product of diacetone acrylamide-fatty acid vinyl ester copolymer and (B) hydrazine A method for producing a heat-sensitive recording material, comprising applying a coating liquid comprising at least one selected from a series compound and a diamine series compound and drying to form a top coat layer.