JPS5856890A - Heat sensitive recording body for infrared laser - Google Patents

Abstract

PURPOSE:To obtain the heat sensitive recording body having practical recording sensitivity when the infrared laser is used as a recording light source, by including a coloring agent, a coloration agent, and an organic compound including water of hydration in the recording layer of the heat sensitive body. CONSTITUTION:In water dispersion painting liquid including well known colorless or a hypochromic basic dye and an inorganic or an organic acidic material, the inorganic compound including water of hydration such as sodium sulfate, potassium sulfate, and magnesium sulfate is added. The amount of addition is 3wt% or more, desirably 10-50wt%, with respect to all the solid state components in the recording layer as an anhydrous component. In the painting liquid, a binder such as starches and hydroxyethyl cellulose is used at a ratio of 15-30wt% with respect to all the solid components. A dispersing agent or other additive agents are added as required. The painting liquid is applied to paper, synthetic fiber paper, and the like so that dry weight of 2-12g/m<2>, desirably 3-10g/m<2> is obtained, and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material for use with an infrared laser that has increased recording sensitivity.

Conventionally, heat-sensitive recording materials are well known, which 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 substances into contact with each other using heat to obtain a colored image. There is.

Further, as a recording method for such a heat-sensitive recording material, a method is generally used in which recording is performed by closely scanning a recording layer with a recording head (thermal head) having a heating element. However, with this type of system, problems such as head wear, debris adhesion to the head surface, and so-called sticking trouble in which the head and recording layer stick together are likely to occur.Furthermore, the recording speed depends on the heat dissipation time of the thermal head. This makes high-speed recording difficult, and there is also a limit to the resolution of colored images created by thermal diffusion. Therefore, instead of such a thermal head contact scanning method, various techniques have been proposed for non-contact recording by scanning with high energy density light such as a laser beam.

In the method of obtaining heat-sensitive recording by scanning such a laser beam, it is necessary to absorb the laser light into a light-to-heat conversion material provided on the recording medium or the device side and convert the energy contained in the laser light into thermal energy. be. In the method of supplying thermal energy to the recording medium after converting it into thermal energy using a light/thermal conversion material on the device side, diffusion and accumulation of thermal energy occur on the light/thermal conversion material, which is not practical. In the method of directly absorbing laser light into a recording medium, a general heat-sensitive recording medium has a wavelength of 400 to 2000 nm.
Because it hardly absorbs visible and near-infrared light, for example, a light-absorbing substance such as colored dye, carbon black, or metal powder may be contained in the recording layer or provided as a layer between the recording layer and the support. Countermeasures such as providing a vapor-deposited metal film on the surface that absorbs laser light are required. However, in either case, the recording layer is colored and the manufacturing process is complicated, so they are not practical.

Focusing on the fact that general heat-sensitive recording materials absorb infrared light, a method using an infrared laser has also been proposed, but this method has not yet achieved practical recording sensitivity.

In view of this current situation, the inventors of the present invention have decided to improve the coloring of the recording layer.
The present invention has been completed as a result of extensive research into recording materials that use infrared lasers as recording light sources in order to obtain laser thermosensitive recording materials that have practical recording sensitivity.

The present invention is a heat-sensitive recording material for an infrared laser, which contains at least a coloring agent, a coloring agent, and an inorganic compound containing crystal water in a recording layer.

Various substances are known as crystal water-containing inorganic compounds, but it is desirable to use substances that are colorless or white and do not cause problems such as increased viscosity during the preparation of heat-sensitive coating liquids.

Specific inorganic compounds include sulfates, carbonates, and silicate compounds of alkali metals and alkaline earth metals, such as sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, sodium carbonate, potassium carbonate, sodium silicate, and potassium silicate. is exemplified. Among these compounds, easily water-soluble neutral salts such as sodium sulfate, potassium sulfate, and magnesium sulfate have a large sensitivity improvement effect and do not deteriorate the quality of thermal recording paper even when used in large amounts. , is particularly preferably used.

These inorganic compounds are generally used as substances containing water of crystallization, but in aqueous coating liquids, they can also be used as anhydrides since they retain crystallized water during the coating and drying steps.

i. The amount of these inorganic compounds added cannot be determined unconditionally as it varies depending on the intensity of the infrared laser beam used, but generally they are added as anhydrides in an amount of 3 weight percent or more based on the total solid content of the recording layer. It may be added in an amount of preferably 3 to 70% by weight, most preferably 10 to 50% by weight.

Among infrared lasers, carbon dioxide lasers are particularly preferably used because high-output infrared laser light can be obtained with a relatively small device, and the recording medium of the present invention is used as a thermal recording medium for carbon dioxide lasers. In this case, wavelength 10
Water-of-crystal-containing inorganic compounds are used which have an absorption in the range ˜11 m.

In the present invention, the color forming agent and coloring agent contained in the recording layer include a combination of a colorless or light-colored basic dye and an inorganic or organic acidic substance, and a combination of a higher fatty acid metal salt such as ferric stearate and a gallic acid. Phenols such as acids,
Examples of such combinations include:

Among these, various types of colorless to light-colored basic dyes are known, and the following are exemplified.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (hereinafter referred to as crystal violet lactone), 13-bis(p-dimethylaminophenyl)phthalide, 3(p-dimethylamino triallylmethane dyes such as phenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 4.4'-
Bis-dimethylaminobenzhydrylbenzyl ether, N-/% lophenyl leucoolamine, N-2,
4,5-) Diphenylmethane dyes such as dichlorophenyl leuco auramine, thiazine dyes such as benzoyl leucomethylene blue and p-nitrobenzyl leucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-
Spiro dyes such as ethyl-spiro-dinaphthopyran, 3-furopyru-spiro-dibenzopyran, 2-anilino-
3-Methyl-6-(N-ethyl-p-toluidino)fluoran, 2T'-toluidino-3-methyl-6-
(N-ethyl-p-toluidino)fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3
-diethylamine-two(2-carbomethoxyanilino)fluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-meranilinofluorane, 3-
Pyrrolidino-6-methyl-7-anilinofluorane, 3
-piperidino-6-methyl-7-anilinofluorane,
3-diethylamino-6-methyl-twochlorofluorane, 3,3-bis(p-dimethylaminophenyl)-6
-Simethylamino 7-thallide, 3-diethylamino-6
-Methyl-7-xylidinofluorane, 3-diethylamino-twochloroanilinofluorane, 7-diethylamino-3-chlorofluorane, 7-diethylamine-3
-Chloro-2-methylfluorane, 3-methyl-6-(
N-p-tolyl-N-ethylamino)fluoran, 3-
Pyrrolidino-6-methyl-7-p-7” thylanilinofluorane, 2-phenylamino-3-methyl-6-(
Fluoran dyes such as N-ethyl-N-p-)lyl)aminofluorane, etc. Various types of inorganic and organic acidic substances are also known that change color when they come into contact with basic colorless dyes, such as the following.

Activated clay, acid clay, attapulgite, bentonite, colloidal silica, inorganic acidic substances such as aluminum maltate, 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'-isopropylidenebis(2-tert-butylphenol), 4
．． 4'-5ec-butylidenephenol, 4-phenylphenol, 4,4'-isopropylidene diphenol, 2,2'-methylenepis (4-chlorophenol), hydroquinone, 4,4'-cyclohexylidine diphenol, novolak Phenolic compounds such as type phenolic resins and phenolic polymers, benzoic acid, p-
tart-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, 3-10-5-(α-methyl Aromatic carboxylic acids such as benzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)tlJ cylic acid, 3t5-cα-methylbenzylsalicylic acid, and these phenols. chemical compounds, aromatic carboxylic acids and e.g. 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 coloring agent and coloring agent used in the recording layer is appropriately selected depending on the type of coloring agent and coloring agent 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, and preferably 4 to 10 parts by weight, of the acidic substance are used per 1 part by weight of the basic colorless dye.

To prepare a coating solution containing these substances, the coloring agent and the coloring agent are generally dispersed together or separately using water as a dispersion medium, stirring with a ball mill, attritor, sand grinder, etc., or using a pulverizer, and then coating. Although prepared as a liquid, the inorganic compound in the present invention may be dispersed simultaneously in these dispersion steps, or may be added to the coating liquid after being dispersed.

In addition, such coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein,
Arabic comb, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc. account for 10 to 40% by weight of the total solids, preferably 15 to 3% by weight.
0% by weight is used. Furthermore, various auxiliary agents can be added to the coating liquid as necessary. For example, dispersants such as sodium dioctyl sulfocononate, sodium dotecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, ultraviolet absorbers such as benzophenone and triazole, and other antifoaming agents. , fluorescent dyes, colored dyes, and the like.

In order to whiten the heat-sensitive recording layer, inorganic pigments such as kaolin, silica, silica talk, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay may be added. In addition, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, matcha oleic acid amide, coconut fatty acid amide, stearic acid, polyethylene, carnauba wax, paraffin wax, calcium stearate, ester wax, etc. Waxes such as dispersions or emulsions can also be added as sensitizers.

In the heat-sensitive recording material of the present invention, there are no particular limitations on the method of forming the coloring layer, and the coloring layer can be formed according to conventionally well-known techniques, such as applying a coating liquid by air knife coating, blade coating, etc. - Formed by drying methods, etc. The amount of coating liquid to be applied is also not particularly limited, but it is usually 2 to 12 y/m by dry weight - preferably 3 to 10 y/m.
y/? It is in the range of ``Fl''.

Although a fat film or the like can be used as appropriate, it is generally preferable to use paper.

EXAMPLES Examples and comparative examples are listed below in order to make the effects of the present invention even clearer, but the present invention is not limited thereto. Note that ``chi'' in the examples represents weight %.

Example 1 Water was added to 25 y of crystal violet lactone and 5 y of 10% polyvinyl alcohol aqueous solution to give a solid content concentration of 25 y.
and bisphenol A1ooI? ,
Stearic acid amide 7'5yS 10% polyvinyl alcohol aqueous solution 5y and water were added to make the dispersion liquid to a concentration of 25%, and each was treated in a porcelain ball mill for 8 hours.

Add 25y of calcium carbonate into the mixed dispersion after treatment.
and sodium sulfate (Na25O411:LoI(2
0) 347 y (equivalent to 153 y as Na2So) was added, and 1000 y of a 10% polyvinyl alcohol aqueous solution was added to obtain a coating liquid for heat-sensitive recording.The obtained coating liquid was coated on high-quality paper of 49 y/WLl'. Dry application amount is '#
/m'' and dried to obtain a blue-colored thermosensitive recording paper.

Example 2 Instead of the sodium sulfate used in Example 1, sodium carbonate (Na2CO3.10H2o) 413y[N a
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that gOO3 corresponds to 153y].

Comparative Example 1 Except for using calcium carbonate ((:!a(!03)153y) instead of sodium sulfate used in Example 1,
A thermosensitive recording paper was obtained in the same manner as in Example 1. Example 3 In place of the crystal violet lactone used in Example 1, 2-phenylamino-3-methyl-6-(N-
A black thermosensitive recording paper was obtained in the same manner as in Example 1 except that ethyl-N-p-)lyl)aminofluorane 25y was used. Comparative Example 2 In Example 3, sodium sulfate was replaced with A thermosensitive recording paper was obtained in the same manner as in Example 3 except that calcium carbonate 153y was used.

The five types of thermal recording papers obtained in Evaluation Test Examples 1 to 3 and Comparative Examples 1 and 2 were irradiated with a carbon dioxide laser with a beam spot diameter of 5 and an output of 1 watt for 8 seconds, and the color density after irradiation was measured using Macbeth. It was measured with a densitometer and the results are shown in Table 1. The Macbeth densitometer was measured using a red filter in Examples 1 and 2 and Comparative Example 1, and a yellow filter in Example 3 and Comparative Example 2.

As is clear from Table 1, the thermal recording paper obtained in the present invention had excellent recording sensitivity as a thermal recording medium for laser use.

Claims (1)

[Claims] (1) A thermal recording material for an infrared laser, which contains at least a coloring agent, a coloring agent, and an inorganic compound containing crystal water in the recording layer.