JPS6046295A - Thermal recording material - Google Patents

Abstract

PURPOSE:To prevent sticking from occurring at the time of printing and contrive to enhance preservability of printed images, by providing a water-soluble resin layer comprising an alkylsulfosuccinic acid salt on a thermal recording layer comprising at least a color former and a color reaction agent. CONSTITUTION:A water-soluble resin coating liquid containing an alkylsulfosuccinic acid salt is sufficiently mixed and dispersed by a mixer or agitator, and then the coating liquid is applied to the thermal recording layer by a coater. The salt is preverably an alkali metal salt or ammonuim salt of an alkylsulfosuccinic acid of the formula, wherein each of R1 and R2 is an alkyl group, and M is an alkali metal or NH4. The amount of the salt used in the coating liquid is preferably 0.01-5wt% as solid. Polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose or the like may be used as a water-soluble resin for providing the water-soluble resin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that has excellent printing stability.

Conventionally, sensitive/thermal recording materials utilize a coloring reaction between a coloring agent and a coloring agent that develops color when they come into contact with the coloring agent, and bring both fully colored substances into contact with each other using heat to obtain a colored image. well known. Such heat-sensitive recording media are relatively inexpensive, and the recording devices are compact and relatively easy to maintain, so they are used not only as recording media for facsimiles and various computers, but also in a wide range of fields.

However, such heat-sensitive recording materials generally have water resistance, oil resistance,
Since it has poor plasticizer resistance, it has the disadvantage that, for example, if the print after coloring comes into contact with water, oil, or a plasticizer contained in a plastic film, the print density will drop significantly. Furthermore, it has a drawback in that it has poor resistance to organic solvents, and if organic solvents adhere to the background area where there is no printing, unnecessary coloring may occur.

As a method to eliminate such drawbacks, there is a method of coating an aqueous emulsion of a resin having film-forming ability and chemical resistance on the heat-sensitive recording layer (Japanese Patent Application Laid-open No. 128347-1982).
, a method of applying a water-soluble polymer compound such as polyvinyl alcohol (Utility Model Application Publication No. 56-125354), and the like have been proposed.

However, improvements come with new drawbacks;
At present, satisfactory results are not necessarily obtained. In other words, when applying a water-based resin coating on a heat-sensitive recording layer, these resin paints do not necessarily have sufficient affinity with the heat-sensitive recording layer, making it difficult to form a resin layer with a uniform thickness, and the proportion of water-based resin coatings in the coating solution increases. If it contains an oily component such as an antifoaming agent, a significant repellency phenomenon may occur on the smeared surface. If the resin layer is uneven and has repelling marks, it will not be possible to achieve the original purpose of providing the resin layer, and not only will the storage stability of the print be poor, but there is also a risk that the resin layer will stick with the thermal head. be.

As a method to eliminate such drawbacks, a proposal was made to incorporate a wetting agent with an HLB value of 4 to 20 into the resin paint (Japanese Patent Application Laid-Open No. 1983-1999).
-122892), although a relatively uniform resin layer is formed by adding a wetting agent, it is difficult to control the penetration of the resin coating liquid into the heat-sensitive recording layer, and the result is still insufficient. This results in a resin layer with uniformity.

In view of the current situation, the inventors of the present invention have conducted extensive research on the resin layer provided on the recording layer, and have found that when an alkyl sulfosuccinate is added to the resin coating liquid, the coating of the resin coating liquid on the heat-sensitive recording layer is reduced. The present inventors have found that the process becomes extremely easy, excessive penetration of the resin coating liquid into the heat-sensitive recording layer is suppressed, and a highly uniform resin layer is formed, leading to the achievement of the present invention.

The present invention is characterized in that a water-soluble resin layer containing an alkyl sulfosuccinate is provided on a heat-sensitive recording layer containing at least a color former and a color former that develops a color when in contact with the color former. It is a heat-sensitive recording medium.

In the present invention, there are no particular limitations on the combination of the coloring agent and the coloring agent contained in the recording layer, and any combination that causes a coloring reaction when the two come into contact with each other due to heat can be used. Examples include combinations of colorless or light-colored basic dyes and inorganic or organic acidic substances, and combinations of higher fatty acid metal salts such as ferric stearate and phenols such as gallic acid. Furthermore, it is also possible to apply the present invention to various heat-sensitive recording materials that obtain a developed color image (recorded image) by heat, such as a heat-sensitive recording material that combines a diazonium compound, a coupler, and a basic substance. It also includes recording media.

However, the specific resin layer of the present invention provided on the recording layer has an excellent effect of improving print storage stability, especially when applied to a combination of a basic dye and an acidic substance, and is therefore particularly preferably used for such a combination.

Various types of colorless to light-colored basic dyes are known, and examples include the following.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl')-3-(1, 2-dimethylindole-3-
yl)phthalide, 3-(p-dimethylaminophenyl)
-3-(2-methylindol-3-yl)phthalide,
3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,3-bis(1°2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3.3-bis(9-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3,3-
Triallylmethane such as bis(2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylvirol-3-yl)-6-dimethylaminophthalide, etc. dyes, 4.4
'-Bis-dimenal aminobenzhydryl benzyl ether, N-halophenyl-leucoolamine, N-2,
Diphenylmethane dyes such as 4,5-toIJ chlorophenyl leuco auramine, thiazine dyes such as benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue, 3-methyl-spiro-dinaphthopyran,
3-ethyl-spiro-dinaphthopyran, 3-phenyl-
Spiro dyes such as spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B-anilinolactam, rhodamine ( Lactam dyes such as p-nitroanilino)lactam and rhodamine(0-chloroanilino)lactam, 3'-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3
-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-(N -ethyl-p-toluidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7- Dibenzylaminofluorane, 3-diethylamino-7-N-methyl-
N-benzylaminofluorane, 3-diethylamino-
7-N-chloroethyl-N-methylaminofluorane,
3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-)luidino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-
p-Toluidino)-6-methyl-7-(p-toluidino)fluoran, 3-diethylamino-6-methyl-7=
Phenylaminofluorane, 3-diethylamino-7-
(2-carbomethoxy-phenylamino)fluorane,
3-(N-ethyl-N 1so-amylamino)-6-
Methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-
Phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-
6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane,
Fluoran series such as 3-diethylamino-7-(0-chlorophenylamino)fluoran, 3-dibutylamino-7-(0-chlorophenylamino)fluoran, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran Dyes etc. Various types of inorganic or organic acidic substances are also known that develop color upon contact with basic colorless dyes, for example, the following are exemplified.

Inorganic acidic substances such as activated clay, acid clay, acpulgite, bentonite, colloidal silica, aluminum silicate, 4-tert-butylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4 -tert-octylcatechol, 2,2'-dihydroxydiphenol, 2,2'-methylenebis(4-methyl-6-tert)
t-isobutylphenol), 4.4'-isopropylidene bis(2-tert-butylphenol), 4.
4'-5ec-butylidenediphenol, 4-phenylphenol, 4.4'-isopropylidenediphenol (bisphenol A), 2.2'-methylenebis(4
- chlorophenol), hydroquinone, 4,4'-cyclohexylidene diphenol, benzyl 4-hydroxybenzoate, dimethyl 4-hydroxyphthalate, hydroquinone monobenzyl ether, novolac type phenolic resin, phenolic polymer, etc. , benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid/3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4 -Hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-
tert-butylsalicylic acid, 3-benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3-chloro-5-(α-methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5 −
Aromatic carboxylic acids such as (α,α-dimethylbenzyl)salicylic acid, 3,5-di-α-methylbenzylsalicylic acid, and these phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, Organic acidic substances such as salts with polyvalent metals such as manganese, tin, and nickel.

In the heat-sensitive recording material of the present invention, the ratio of the color former and color former in the recording layer is appropriately selected depending on the type of color former and color former used, and is not particularly limited. For example, when using a basic colorless dye and an acidic substance,
Generally, 1 to 50 parts by weight, preferably 2 to 10 parts by weight of acidic substance are used per part by weight of basic colorless dye.

For steel coating solutions containing these substances, generally water is used as a dispersion medium, and a coloring agent and a coloring agent are dispersed together or separately using a ball mill, an attritor, a sand grinder, etc., using an agitation machine or a pulverizer. Prepared as a coating liquid. Such coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diisobutylene/anhydrous? Leic acid copolymer salt, styrene/maleic anhydride copolymer salt,
Ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc. are used in an amount of 10 to 70% by weight, preferably 15 to 50% by weight of the total solid content. Furthermore, various auxiliary agents can be added to the coating liquid.

For example, dispersants such as dioctyl sodium sulfosuccinate, dotesylhenzensulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, ultraviolet absorbers such as benzophenone and triazole, and other antifoaming agents. agents, fluorescent dyes, colored dyes, etc.

In addition, waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, Inorganic pigments such as activated clay, and sensitizers such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, matcha oleic acid amide, and coconut fatty acid amide can also be added.

In the heat-sensitive recording material of the present invention, there are no particular limitations on the method of forming the recording layer, and the recording layer can be formed according to conventionally known and commonly used techniques, such as air knife coating, blade coating, etc. It is formed by coating and drying methods. Further, the amount of coating liquid applied is not particularly limited, but it is usually 2 to 12 g/rd, preferably 3 to 1 g/rd in terms of dry weight.
It is in the range of 0 g/d.

As described above, the heat-sensitive recording material of the present invention has an important feature in that a water-soluble resin layer containing an alkyl sulfosuccinate is provided on the recording layer thus formed. As fosuccinate,
In particular, an alkali metal or ammonium salt of alkylsulfosuccinic acid represented by the following general formula is more preferably used.

CR2-COOR.

[In the formula, R,, R, represents an alkyl group, and M represents an alkali metal or NH4. ] In the present invention, the alkyl group of the alkyl sulfosuccinate is not particularly limited, and examples include squid, 03-C
04-c8 alkyl groups are more preferred, and specific examples include isobutyl, amyl, hexyl, cyclohexyl, octyl, and 2-ethyl-hexyl groups.

Among these, octyl group and 2-ethyl-hexyl group are the most preferred alkyl groups because they are excellent in achieving the desired effects of the present invention.

Furthermore, in the above general formula, a so-called symmetric alkyl sulfosuccinate in which R/ and R2 are the same dialkyl group is particularly preferably used because it is also excellent in achieving the desired effects of the present invention.

Note that when the proportion of the alkyl sulfosuccinate added to the water-soluble resin coating liquid is less than 0.01% by weight in terms of solid content, the suitability of the resin coating liquid for coating on the heat-sensitive recording layer is almost negligible. It is not possible to form a resin layer with high uniformity. However, if the addition ratio becomes too large, for example, if the solid content exceeds 5% by weight, the resin coating liquid will foam, resulting in an uneven resin layer. Therefore, the proportion of the alkyl sulfosuccinate added to the water-soluble resin coating liquid is adjusted in the range of 0.01 to 5% by weight, more preferably 0.2 to 2% by weight in terms of solid content. is desirable.

In the present invention, examples of the water-soluble resin used to form the water-soluble resin layer containing the alkyl sulfosuccinate on the recording layer include polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, forged powder, and the like. Examples include derivatives, casein, sodium alginate, polyvinylpyrrolidone, sodium polyacrylate, polyacrylamide, styrene-maleic acid copolymer salt, polyurethane resin, urea resin, melamine resin, and the like.

In the present invention, a pigment may be added to the specific water-soluble resin coating liquid containing the alkyl sulfosuccinate, if necessary, in order to improve the printability and sticking of the resin layer.

Specific examples of such pigments include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc,
Examples include inorganic pigments such as kaolin, clay, calcined clay, and colloidal silica, and organic pigments such as styrene microspheres, nylon powder, polyethylene powder, urea/formalin resin fillers, and raw starch granules. The amount used is generally desirably in the range of 5 to 500 parts by weight per 100 parts by weight of the resin component.

Furthermore, various auxiliary agents such as lubricants such as zinc stearate, calcium stearate, stearamide, polyethylene wax, carnauba wax, paraffin wax, and ester wax, dispersants, and antifoaming agents are added to the resin coating solution as necessary. It can also be added.

In the present invention, if a specific water-soluble resin coating solution containing alkyl sulfosuccinic salt is sufficiently mixed and dispersed using a mixing/stirring machine such as a mixer, attritor, ball mill, or roll mill as necessary, the coating solution may be coated using a known coating method. It is coated onto the heat-sensitive recording layer using a device.

The amount of resin coating liquid applied is not particularly limited, but
If it is less than 0.1 g/nf, the desired effect of the present invention cannot be sufficiently obtained, and if it exceeds 20 g/nf, the recording sensitivity of the heat-sensitive recording medium may be significantly reduced. 0.1-20g/I, preferably 1-IO
It is desirable to adjust it within the range of g/%.

Thus, in the present invention, by providing a specific water-soluble resin layer containing an alkyl sulfosuccinate on the heat-sensitive recording layer, a heat-sensitive record with excellent print storage stability without new problems such as sticking can be achieved. It's what the body gets.

Note that, if necessary, it is also possible to further improve the storage stability by providing such a resin layer on the back side of the heat-sensitive recording material. Furthermore, various known techniques in the field of heat-sensitive recording material production may be added as necessary, such as providing an undercoat layer on the support, applying an adhesive treatment to the back surface of the recording material, and processing it into an adhesive label.

The present invention will be described in more detail with reference to Examples below, but it is of course not limited thereto.

Note that parts and % in the examples indicate parts by weight and % by weight, respectively, unless otherwise specified.

Example 1 ■ Preparation of liquid A 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane 10 parts Methylcellulose 5% aqueous solution 5 parts Water 30 parts This composition was ground with a sand grinder to an average particle size of 3 μm.

(2) Preparation of Solution B 4.4'-Isopropylidenediphenol 20 parts Methylcellulose 5% aqueous solution 5 parts Water 55 parts This composition was ground with a sand grinder to an average particle size of 3 μm.

(2) Formation of Recording Layer 45 parts of liquid A, 80 parts of liquid B, 50 parts of a 20% oxidized starch aqueous solution, and 10 parts of water were mixed and stirred to prepare a coating liquid. The obtained coating liquid was coated and dried on a base paper of 50 g/rrr so that the coated amount after drying was 5 g/m to obtain a heat-sensitive recording paper.

On the recording layer of the obtained thermosensitive recording paper, a resin coating liquid having the following composition: 10% polyvinyl alcohol aqueous solution, 100 parts calcium carbonate, 20 parts sodium dioctyl sulfosuccinate (manufactured by Nippon Oil & Fats Co., Ltd., Nisosan Ravisol) B-80) 0.2 parts Foaming agent (manufactured by San Nobuco Co., Ltd., Nopco 1.407K) 0.1
A resin-coated thermosensitive recording paper was obtained by coating and drying 50 parts of water so that the coating amount after drying was 6 g/rd.

Comparative Example 1 Example 1 except that sodium dioctyl sulfosuccinate was not blended in the resin coating composition in Example 1.
Comparative Examples 2 to 4 of resin-coated thermosensitive recording paper were prepared in the same manner as in Example 1. In the resin coating composition of Example 1, the following compounds were used instead of sodium dioctyl sulfosuccinate. A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1 except that M lubricant was used.

・Comparative Example 2 Polyethylene glycol nonyl lauryl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neugen ET-120) ・Comparative Example 3 Polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neugen EA-120) ・Comparative Example 4 Alkylnaphthalene Sodium sulfonate (manufactured by Kao Atlas Co., Ltd., Neoperex NB Paste) The five types of resin-coated thermal recording paper thus obtained were applied to a thermal recording printer (Texas Instruments Co., Ltd., 51.
PC-100A) to evaluate the occurrence of sticking, and the results are shown in Table 1. Next, a thermal gradient tester (manufactured by Toyo Seiki Co., Ltd., 1 condition; 120°C, 2
kg/c4. 10 seconds) to develop the print color, and adjust the initial print color density using the Macbeth density needle (manufactured by Macbeth Co., Ltd., RD-1).
00R type.

(using an amber filter), and the results are shown in the first
Shown in the table. Further, the color density after each evaluation test of plasticizer resistance, oil resistance, and organic solvent resistance shown below was measured using a Macbeth density needle, and the results are listed in Table 1.

Plasticizer resistance: A vinyl chloride lamp film (manufactured by Mitsui Toatsu Co., Ltd.) is wrapped three times around a polypropylene pipe (40mmφ tube), and on top of that, thermal recording paper that has been colored with a thermal gradient tester is placed so that the colored side of the print is on. The paper was sandwiched so that it was facing outward, and then a vinyl chloride lamp film was wrapped five times over it, and the print density was measured after 72 hours.

(The larger the number, the better the plasticizer resistance.) Oil resistance: Add a few drops of edible soybean oil to the printed color area,
After 4 hours, the soybean oil was wiped off with gauze, and the density of the printed area was measured.

(The higher the number, the better the oil resistance) Organic solvent resistance: Add a few drops of ethyl acetate to the skin,
After 30 minutes, the color density of the background area was measured.

(The smaller the number, the better the organic solvent resistance) Table 1 1) Sticking evaluation criteria ◎: Not occurring at all.

○: Slight occurrence, but no practical problem.

△: Quite a few occurrences, and there is a quality problem.

×: Occurs violently and is not suitable for practical use.

As is clear from the results in Table 1, the heat-sensitive recording material according to the present invention was a recording material that did not cause sticking during printing and had extremely excellent print storage stability.

Patent applicant Kanzaki Paper Co., Ltd. 547-

Claims (1)

[Claims] +11 A water-soluble resin layer containing an alkyl sulfosuccinate is provided on a heat-sensitive recording layer containing at least a color former and a color former that develops a color when in contact with the color former. A heat-sensitive recording material characterized by: (2) The water-soluble resin layer contains 0.01 to 5% by weight (solid content) of alkyl sulfosuccinate (
1) The heat-sensitive recording medium described in item 1). (3) The heat-sensitive recording material according to claim 11 or (2), wherein the alkyl sulfosuccinate is an alkali metal salt or ammonium salt of alkyl sulfosuccinic acid.