JPH05338353A - Thermal recording material - Google Patents

Abstract

PURPOSE:To prevent the deformation or damage of a thermal recording material due to bending by adding a compd. represented by a predetermined general formula and an acrylic acid/ethylene copolymer represented by a predetermined general formula to the thermal recording layer formed on a polyurethane support. CONSTITUTION:In a thermal recording material obtained by providing a thermal color forming layer based on a colorless or light-colored color forming compd. and a developer allowing the color forming compound to foot a color at the time of heating on a support such as a polyurethane sheet, 1-10 pts.wt. of a developer represented by formula I (wherein R1-R3 are hydrogen, a 5C or less alkyl group or an alkenyl group) and 1-80wt.% of an acrylic acid/ethylene copolymer represented by formula II (wherein n is 1000 or less and X is hydrogen, Na, K, NH4 or alkanolamine) being a binder are added to the thermal color forming layer. For example, as the color forming compd., a fluorane compd. is used and, as the developer, 4,4'-sulfonyldiphenol is used and, as the copolymer, one with a mol.wt. of 100000 or less and an acid value of about 150, for example, Zaiksen (phonetic)-A(NH4 salt) is used.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive recording material.
More specifically, the present invention relates to a heat-sensitive recording material which is not deformed or damaged by bending and has excellent color development and high storage stability.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is prepared by separately dispersing a leuco dye and a color developing agent such as a phenolic substance in the form of fine particles and mixing them together, and then adding a binder, a sensitizer, a filler, It is a coating liquid prepared by adding additives such as lubricants, and it is applied to paper, film, synthetic paper, etc., and it develops color by a chemical reaction that occurs when one or both of the leuco dye and the color developer melt and contact when heated. Get the record. A thermal printer or the like having a built-in thermal head is used for coloring the thermal recording sheet. Compared with other recording methods, this thermal recording method (1) produces no noise during recording,
Due to the features such as (2) no need for development and fixing, (3) maintenance-free, (4) relatively inexpensive machines, the field of facsimiles, computer output, printers such as calculators, medical It is widely used in the fields of measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

Conventionally, hard plastic films typified by paper, synthetic paper and polyester films have been used as a support for such materials. These are selected because it is easy to keep a flat surface and the surface is uniform, according to the conventional wisdom of handwriting.However, in the case of recording by contact with the thermal head surface like the thermal recording method, the recording sheet surface is It is preferable to follow the surface of the thermal head as much as possible. For this reason, in addition to the flatness and smoothness of the recording sheet, conditions such as softness and flexibility also have a great effect on the print quality. When ordinary papers are used as a support, when they are bent or folded, they often have creases or scratches due to their hardness and flatness, which impair normal printing or image recording.

There is an application of a polyurethane-based synthetic polymer as a material which does not have such inconvenience and can serve as a physically and chemically stable support. However, due to the chemical structure of polyurethane, which has a reducing urethane bond, the heat-sensitive color development method that uses a leuco dye has a problem that it impairs the color development function and causes printing defects and decolorization of the recording layer. There is.

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
It is to solve the drawbacks of the prior art. That is, it is to provide a heat-sensitive recording material which is not deformed or damaged by folding or bending, has excellent color developability, and has high storage stability.

[0006]

The inventors of the present invention have completed the present invention as a result of various studies to achieve the above object. That is, the present invention is a heat-sensitive color-forming layer comprising a polyurethane or a support processed with polyurethane, which is provided with a colorless or light-colored color-forming compound and a color-developing compound capable of developing a color when the color-forming compound is heated. A heat-sensitive recording material comprising a recording material containing a compound of the following formula (1) and a copolymer of acrylic acid and ethylene represented by the following formula (2).

[0007]

[Chemical 3]

(In the formula (1), R ₁ , R ₂ and R ₃ represent hydrogen or an alkyl group or an alkenyl group having 5 or less carbon atoms.)

[0009]

[Chemical 4]

(In the formula (2), n is 1,000 or less, X is hydrogen or Na, K, NH ₄ or alkanolamine.)

The present invention will be described in detail. The polyurethane or the support processed with polyurethane used in the present invention includes, as an example of a single form, a polyurethane sheet, a polyurethane film and the like. Examples of polyurethane processing include thermoplastic synthetic resins such as polypropylene, polyester, and polycarbonate films, and sheet-shaped polyurethane bonded to cloth, or as disclosed in JP-A-3-21487. Polyurethane / DM for sheet woven or non-woven fabric
It is possible to use a form obtained by applying an F (dimethylformamide) solution, immediately immersing it in water to coagulate the coating film, and then performing solvent extraction. The types of polyurethane include adipate, caprolactone, polycarbonate,
There are thermoplastic polyurethane (TPU) having a long chain polyol such as ether type and PTMG as a main chain, and other polyurethane type synthetic polymers.

Next, the heat-sensitive recording layer of the present invention contains the compound of formula (1) as a color-developing compound and the copolymer of acrylic acid and ethylene of formula (2) as a binder, and if necessary, The thermosensitive coloring layer is prepared by using the following fillers, heat-fusible compounds and surfactants in combination. The use ratio in the heat-sensitive color forming layer is 1 to 10 parts by weight, preferably 1 to 5 parts by weight, of the color-developing compound of the formula (1) per 1 part by weight of the color-forming compound. The copolymer of formula (2) is contained in the thermosensitive coloring layer in an amount of 1 to 80% by weight, preferably 10 to 30% by weight.
It is included. Further, other color-developing compound or binder may be used in combination in the color forming layer.

Examples of the color forming compound include the following. That is, a fluoran compound, a triarylmethane compound, a spirolylan compound, a diphenylmethane compound, a thiazine compound, a lactam compound, a fluorene compound and the like can be mentioned, and specific examples thereof include the following compounds. Fluoran compounds; 2-aniline-3-methyl-6-
Diethylaminofluorane, 2-anilino-3-methyl-6-dibutylaminofluorane, 2-anilino-3-
Methyl-6- (N-methyl-N-cyclohexylamino) fluorane, 2-anilino-3-methyl-6- (N
-Ethyl-N-isopentylamino) fluorane, 2-
Anilino-3-methyl-6-isobutylethylaminofluorane, 2-anilino-3-methyl-6- [N-ethyl-N- (3-ethoxypropyl) amino] fluorane, 2-anilino-3-methyl-6 -(N-ethyl-N
-Hexylamino) fluorane, 2-anilino-3-methyl-6-dipentylaminofluorane, 2- (p-chloroanilino) -3-methyl-6-diethylaminofluorane, 2- (p-fluoroanilino) -3 -Methyl-
6-diethylaminofluorane, 2-anilino-3-methyl-6- (p-toluidinoethylamino) fluorane, 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, 2- (o- Chloroanilino) -6
-Diethylaminofluorane, 2- (o-chloroanilino) -6-dibutylaminofluorane, 2- (o-fluoroanilino-6-diethylaminofluorane, 2-
(O-Fluoroanilino) -6-dibutylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-anilino-3-methyl-6-pyrrolidinofluorane, 2-ethoxyethyl Amino-3-chloro-6
-Diethylaminofluorane, 2-anilino-3-chloro-6-diethylfluorane, 2-chloro-6-diethylaminofluorane, 2-methyl-6-diethylaminofluorane, etc.

Triarylmethane compound; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-Dimethylaminoindole-3-) isophthalide and other spiropyran compounds; 3-methyl-3-spiro-dinaphthopyran, 1,3,3-trimethyl-6-
Nitro-8'-methoxyspiro (indoline-2,2 '
-Benzopyran) and the like; diphenylmethane-based compounds; -halophenyl-leukoauramine and other thiazine-based compounds;
Lactam compounds such as benzoyl leuco methylene blue; fluorene compounds such as rhodamine-B-anilinolactam; 3,6-bis (dimethylamino) fluorenspyrro (9,3 ′)-6′-dimethylaminophthalide, 3, 6-bis (dimethylamino) fluorene spiro (9,3 ′)-6′-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenspiro (9.
3 ')-6'-Pyrrolidinophthalide These color forming compounds may be used alone or in combination.

Examples of the color-developing compound include 4,4'-sulfonyldiphenol and 4,4'-sulfonyl-bis-
(2-allylphenol), 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4'-ethoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-
4'butoxydiphenyl sulfone and the like can be used.

Further, examples of the color-developing compound which can be used in combination are as follows. α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, p-t-butylphenol, p-phenylphenol, 1,1′-bis (p-hydroxyphenyl) propane, 2,2′-bis- (P-Hydroxyphenyl) propane, 2,2'-bis (p-hydroxyphenyl) butane, 1,1'-bis (p-hydroxyphenyl) cyclohexane, 4,4'-thiobisphenol, 4,4 '
-Cyclo-hexylidene diphenol, 2,2'-bis (2,5-dibromo-4-hydroxyphenyl) propane, 4,4'-isopropylidene bis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), methyl bis (4-hydroxyphenyl) acetate, bis (4-hydroxyphenyl) butyl acetate, phenolic compounds such as benzyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, p -Ethyl hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxydiphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, etc. Aromatic carboxylic acid derivatives, aromatic carboxylic acids or polyvalent metal salts thereof, etc. may be mentioned. That.

An example of a copolymer of acrylic acid and ethylene as a binder is a compound having a monomer component of acrylic acid and ethylene and having a molecular weight of about 100,000 or less and an acid value of about 150. It is marketed under the brand name (Sumitomo Seika Co., Ltd. product). Water-soluble types include Saixen-A (NH ₄ salt) and Saixen-AC (NH ₄ salt).
Salt), Saixen-L (alkanolamine salt), Saixen-N (Na salt) and the like, and resin types include Saixen-F and Saixen-FP.

Further, examples of the binder that can be used in combination include the following. Methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and derivatives thereof. , Casein, gelatin water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer Iso (or diiso) butylene / alkali salt of maleic anhydride copolymer, water-soluble one or polyvinyl acetate / vinyl acetate copolymer Polymer, polystyrene, polyacrylic acid ester, polyurethane, styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene ( B) copolymers,
Styrene / butadiene / acrylic acid type copolymers, water-soluble emulsions such as composite particles of colloidal silica and acrylic resin.

Examples of fillers that can be used are calcium carbonate, magnesium carbonate, magnesium oxide, silica,
There are white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, urea-formalin resin and the like.

Examples of the heat-fusible compound that can be used include waxes such as animal and vegetable wax, polyethylene wax, and synthetic wax, and higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, and aromatic ethers. Examples thereof include compounds and biphenyl derivatives which are solid at room temperature and have a melting point of about 80 ° C. or higher. In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, antifoaming agents and the like are added as necessary.

The heat-sensitive recording material of the present invention is prepared using the above-mentioned material by the following method, for example. That is, according to a conventional method, the color-developing compound and the color-developing compound represented by the above formula (1) are separately separately added together with a binder or, if necessary, other additives in a dispersing machine such as a ball mill, an attritor or a sand mill. After pulverizing and dispersing, the copolymer of the general formula (2) is added so as to have a dry solid content of 10 to 30% by weight to prepare a thermosensitive coloring layer coating solution. Then, the prepared liquid is applied onto a support processed with polyurethane by a bar coater so that the dry weight is usually 1 to 20 g / m ² .
Coating with a blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually 1: 1 to 1:10 by dry weight ratio) and drying to obtain the heat-sensitive recording material of the present invention.

If necessary, an intermediate layer may be provided between the support and the thermosensitive coloring layer, or an overcoat layer may be provided on the thermosensitive coloring layer. The above-mentioned compound of formula (1) and formula (2)
The heat-sensitive recording material of the present invention containing the above-mentioned copolymer is softer, has better matching with the thermal head surface, is excellent in color developability, and has a high storage stability as compared with the conventionally known materials. Further, it is a thermosensitive recording material which is hardly deformed by bending and is not scratched.

[0023]

EXAMPLES The present invention will be described more specifically by way of examples, but the present invention is not limited thereto. In the examples, "part" indicates part by weight.

Example 1 A mixture having the following composition was pulverized with a sand grinder for 30 minutes to prepare solutions [A] and [B], respectively. [A] liquid: 2-anilino-3-methyl-6-dibutylaminofluorane 40 parts 25% PVA aqueous solution 20 parts water 40 parts [B] liquid: 4,4′-sulfonyl-bis- (2-allylphenol) 20 parts p-benzylbiphenyl 20 parts 25% PVA aqueous solution 20 parts water 40 parts

Then, the thermosensitive color developing layer coating liquid was prepared by mixing in the following proportions. Liquid [A] 5 parts Liquid [B] 50 parts Saixen AC (30% acrylic acid / ethylene copolymer NH ₄ salt aqueous solution 20 parts 70% calcium carbonate aqueous dispersion 10 parts water 15 parts

The thermosensitive coloring layer coating solution was applied onto an adipate-type thermoplastic polyurethane elastomer (manufactured by Nippon Miractolan; trade name E-795) so that the dry weight was about 12 g / m ^2. After coating and drying, a heat-sensitive recording material of the present invention was obtained.

Example 2 The procedure of Example 1 was repeated except that 4,4′-sulfonyl-bis- (2-allylphenol) in Example 1 was replaced with 4,4′-sulfonyldiphenol. A heat-sensitive recording material of the invention was obtained.

Example 3 As Example 1 except that 4-hydroxy-4′-isopropoxydiphenyl sulfone) was used in place of 4,4′-sulfonyl-bis- (2-allylphenol) of Example 1. Similarly, a heat-sensitive recording material of the present invention was obtained.

Example 4 A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that an ether thermoplastic polyurethane elastomer was used in place of the adipate thermoplastic polyurethane elastomer of Example 1.

Fifth Embodiment Instead of the Saixen AC of the first embodiment, a Saixen-L is used.
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that (25% alkanolamine salt) was used.

Embodiment 6 Instead of the Saixen AC of the first embodiment, a Saixen-N is used.
A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that (25% Na salt) was used.

Comparative Example 1 A thermosensitive recording material for comparison was obtained in the same manner as in Example 1 except that carboxylated styrene / butadiene copolymer latex was used instead of Saixen-AC in Example 1.

Comparative Example 2 4,4'sulfonyl-bis-in the liquid [A] of Example 1
Bisphenol A instead of (2-allylphenol)
Also, instead of Saixen-AC, PVA (saponification degree =
86.5 to 89.0 mol%, degree of polymerization = 1,000 or less)
A thermal recording material for comparison was obtained in the same manner as in Example 1 except that was used.

COMPARATIVE EXAMPLE 3 A heat-sensitive material for comparison was prepared in the same manner as in Example 1 except that, instead of the thermoplastic polyurethane elastomer used in Example 1, woodfree paper having a basis weight of about 50 g / m ² was used as a support. A recording material was obtained.

Comparative Example 4 A thermal recording material for comparison was prepared in the same manner as in Example 1 except that a transparent polyester film having a thickness of 100 μm was used as a support instead of the thermoplastic polyurethane elastomer used in Example 1. Obtained. The following quality tests were carried out on the heat-sensitive recording materials of the present invention and comparative examples obtained as described above.

Table 1 Quality performance test Color density Moisture and heat resistance (%) Flex resistance Example 1 1. 50 90 ○ Example 2 1. 45 91 ○ Example 3 1. 52 89 ○ Example 4 1. 50 89 ○ Example 5 1. 51 90 ○ Example 6 1. 50 90 ○ Comparative Example 1 1. 44 59 ○ Comparative Example 2 1. 11 75 ○ Comparative example 3 1. 54 98 Δ to × Comparative Example 4 1. 56 99 x

1) Color density: A value measured by a Macbeth reflection densitometer RD-914 type on a sample printed by a thermal printer (D-508P) manufactured by Ishida Koki Co., Ltd. 2) Moisture and heat resistance: 40 samples of the color developed by the above printer
Remaining rate (%) of the image area after leaving for 24 hours in a thermo-hygrostat at a temperature of 90 ° C and a relative humidity of 90%. 3) Flex resistance: According to the flex test of JIS K 5400. The restored state of the sample when a mandrel having a diameter of 2 mm under the strongest condition of a bending tester (manufactured by Tester Sangyo Co., Ltd.) was used and the printing quality when printing was performed by the above printer were determined. ○ The appearance and print quality are the same as before the test △ Folding occurred, but the print quality was the same × Folding occurred and the print quality was poor

As is apparent from the table, the thermosensitive recording material of the present invention has excellent color density, storability and flexibility.

EFFECTS OF THE INVENTION It is hard to be deformed by bending and is not scratched. Therefore, a heat-sensitive recording material having good matching with the thermal head surface, excellent color development and good storage stability was obtained.

Claims (1)

[Claims] 1. A heat-sensitive coloring layer comprising a polyurethane or a support processed with polyurethane, and a thermosensitive coloring layer mainly composed of a colorless or light-colored coloring compound and a developer compound capable of coloring the coloring substance under heat. A heat-sensitive recording material comprising a compound of the following formula (1) and a copolymer of acrylic acid and ethylene represented by the following formula (2) in the recording material. [Chemical 1] (In the formula (1), R ₁ , R ₂ and R ₃ represent hydrogen or an alkyl group or an alkenyl group having 5 or less carbon atoms. (In the formula (2), n is 1,000 or less, X is hydrogen or N
a, K, NH ₄ , and alkanolamine. )