JPS60179290A - Heat sensitive recording sheet with raised chemical resistance - Google Patents

Abstract

PURPOSE:To achieve the rise of chemical resistance, by containing minute fibrous cellulose in the overcoat layer having film forming high molecular compound provided on the heat sensitive coloring layer as main component. CONSTITUTION:Minute fibrous cellulose is contained in the overcoat layer with the chemical resistant heat sensitive recording sheet for which the heat sensitive coloring layer having colorless or light colored dyestuff precursor and developer coloring the dyestuff precursor by reaction when heated as principal constitutional elements, is provided and further the overcoat layer having principally film forming high molecular compound is provided on this heat sensitive coloring layer. For this heat sensitive recording paper, the coating liquid is prepared by a method wherein phenol substance or organic acid and dyestuff precursor coloring with phenol substance or organic acid and separately, or otherwise at the same time ground to be dispersed in minute particulate, mixed with binder, pigment, etc. and added with various additives, if necessary. For the binder, starch or the like are used. For the material forming the overcoat layer, water-soluble high molecular compound is, as a rule, used. The added amount of minute fibrous cellulose into the overcoat layer shall be 0.3wt% min.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording sheet whose main components are a dye precursor and a color developer that develops color when the dye precursor is heated. The present invention provides a heat-sensitive recording sheet that prevents the above-mentioned heat.

Thermal recording method is non-impact and produces no noise during recording.
Because it has many features such as not requiring development and fixing and easy equipment maintenance, it is used in a wide variety of applications, including various printers, telephone facsimile IJ, barcode labels, and tickets.

The characteristics required for this type of heat-sensitive recording sheet include, of course, sensitivity suitable for various uses, as well as a white background, long-term stability of colored images that do not fade, and the ability to avoid scratches during recording. There are some problems, such as the fact that there is no sticking to the thermal head during recording, and so on.

Excellent products that meet many of these requirements can be manufactured, but in practical handling after recording, if they come into contact with erasers or vinyl chloride bags containing a large amount of plasticizer,
If you touch it with hands that have hand cream or hair styling oil on it, or if you overlap it with diazo photosensitive paper that has just been processed,
When an underline or the like is written with a highlighter, the image may disappear or the background may become colored, making it difficult to read the recorded image. This discoloration phenomenon is thought to be because the lactone ring of the color-forming lactone compound, which is ring-opened with an acidic color developer, is closed in the presence of a plasticizer such as dibutyl phthalate, dioctyl phthalate, or dioctyl adipate. There is. Further, the fogging phenomenon is thought to be caused by the developer of the diazo photosensitive paper and the solvent contained in the highlighter pen dissolving the color developer and bringing it into contact with the dye precursor, thereby stopping the color development reaction.

Therefore, it has been proposed that this phenomenon can be prevented by forming a film on the heat-sensitive recording sheet to prevent the penetration of the plasticizer. (Japanese Unexamined Patent Applications No. 54-128347, No. 54-3549) The present inventors also developed an overcoat agent having chemical resistance and filed a patent application No. 55-18255.
No. 7, patent application No. 56-981 has been filed.

However, conventionally, the overcoat layer @ film is prone to cissing, pinholes, unevenness, etc., and satisfactory chemical resistance cannot be obtained unless it is coated very thickly.
It takes a lot of drying time and the smearing speed cannot be increased, etc.
This not only caused problems in terms of production, but also caused a decrease in sensitivity, which was undesirable. Therefore, attempts have been made to add a variety of surfactants for the purpose of improving the leveling properties of the coating film, but this method significantly deteriorates the water and oil resistance of the coating film, and at the same time, it is difficult to preserve the blank areas and recorded areas over time. It also deteriorated my sexuality. Although the leveling property can be improved to some extent by adding pigments, this method is unsatisfactory at present because it inhibits film formation, reduces color development sensitivity, and causes wear of the facsimile (facsimile) thermal head.

The present inventor has created an overcoat layer that prevents the occurrence of cissing, pinholes, and unevenness, and that does not impede heat conduction as much as possible, and that does not cause deterioration of water resistance or oil resistance, and does not inhibit color development or decrease sensitivity. As a result of extensive research into a heat-sensitive recording sheet with improved chemical resistance and good print quality, the present invention was arrived at.

That is, the present invention provides a film-forming polymer compound provided on a heat-sensitive color-forming layer, the main components of which are a colorless to light-colored dye-resistant precursor and a color developer that reacts with the dye precursor upon heating to form a color. An object of the present invention is to provide a heat-sensitive recording sheet with improved chemical resistance, which is characterized by containing fine fibrous cellulose in an overcoat layer mainly composed of.

The main components used in the present invention will be explained in detail below, but the present invention is not limited to 15N unless it goes beyond the gist of the present invention.

Table 1 shows typical examples of dye precursors that develop color with phenolic substances or organic acids.

Table 1 (1) Crystal violet lactone (2) 3-indolino-3-1-dimethylaminophenyl-6-dimethylaminophthalide (3) 3-diethylamino-7-chloro 77-inch lactone (
4) 3-diethylamino-7-cyclohexylaminofluorane (5) 3-diethylamino-5-methyl-7-butylfluorane (6) 3-diethylamino-6-methyl-7-anilinofluorane (7) 3-diethylamino-6-methyl-7-p-butylanilinofluorane (8) 2-(N-phenyl-N-ethyl)aminofluorane (9) 3-diethylamino-7-dibenzylaminofluorane ( 10) 3-Cyclohexylamino-6-chlorofluorane (11) 3-diethylamino-6-methyl-7-xylidinofluorane + 12) 2-anilino-3-methyl-6-(N-ethyl-p-toluidino) Fluorane (13) 3-pyrrolidino-6-methyl-7-anilinofluorane (14) 3-pyrrolidino-7-cyclohexylaminofluorane (15) 3-piperidino-6-methyl-7-toluidinofluorane ( 16) 3-piperidino-6-methyl-7-anilinofluorane (17) 3-(N-methylcyclohexylamino)-6
-Methyl-7-anilinofluorane (18) 3-diethylamino-7-(m-trifluoromethylanilino)7-fluorane (19) 3-diethylamino-6-methyl-7-chlorofluorane Next, the present invention Table 2 shows typical examples of phenolic substances or organic acids (color developers) used in

Table-2 (1) 4.4'-isopropylidenediphenol (2
) 4.4'-isopropylidene bis(2-chlorophenol) (3) 4.4'-isopropylidene bis(2-tert-butylphenol) (4) 4.4'-Secondary-butylidene diphenol (5) 4 .4'-(1-Methyl-n-hexylidene)diphenol (6) 4-phenylphenol (7) 4-hydroxydiphenoxide (8) Methyl-4-hydroxybenzoate (9) Phenyl-4-
Hydroxybenzoate (10) 4-Human O-oxyacetophenone (11) Salicylic acid anilide (12) 4.4'-Cyclohexylidene diphenol (13) 4.4'-Cyclohexylidene bis(2-methylphenol) (14) 4 .4'-benzylidenediphenol (15
) 4.4'-thiobis(6-tert-butyl-3
= methylphenol) (16) 4.4'-isopropylidene bis(2-methylphenol) (17) 4.4'-ethylenebis(2-methylphenol) (18) 4.4'-cyclohexylidene bis(
2-isopropylphenol) (19) 2,2'-dihydroxydiphenyl (20)
2.2'-methylenebis(4-chlorophenol) (
21) 2.2'-methylenebis(4-methyl-6-t
-butylphenol) (22) 1.1'-bis(4-hydroxyphenol)-cyclohexane (23) 2.2-bis(4'-hydroxyphenyl)
Propane (24) Novolac type phenolic resin (25) Halogenated novolac type phenolic resin (2
6) a-naphthol (27) β-naphthol (28) 3.5-di-t-butylsalicylic acid (29)
3.5-di-α-methylbenzylsalicylic acid (30)
3-Methyl-5-t-butylsalicylic acid (31) Phthalic acid monoanilide barethoxybenzoic acid (32) Parabenzyloxybenzoic acid (33) Parahydroxybenzoic acid benzyl ester The thermal recording paper of the present invention can be prepared by the following method. Obtainable. That is, a phenolic substance or an organic acid, and a dye precursor that develops color with the phenolic substance or organic acid are ground and dispersed separately or simultaneously in a grinder into fine particles, mixed with a binder, pigment, etc. The coating liquid is prepared by adding additives.

Examples of binders include starches, hydroxyethyl cellulose, methyl cellulose, polyvinyl alcohol,
Water-soluble binders such as styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyacrylamide, carboxymethyl cellulose, gum arabic, casein, etc. Latexes such as styrene-butadiene latex can be used.

Examples of pigments include aluminum hydroxide, heavy and light calcium carbonate, zinc oxide, titanium oxide, barium sulfate, silica gel, activated clay, talc, clay, satin white, kaolinite, calcined kaolinite, diatomaceous earth, synthetic Examples include kaolinite, polyolefin particles, polystyrene particles, urea-formalin resin particles, and the like.

Next, regarding the material forming the overcoat layer in the present invention, water-soluble polymer compounds are generally preferred;
Among these, alginates alone or those in which alginate is essential and are used in combination with one or more polymeric compounds selected from hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol are preferable. (Special Application No. 152455, 1983)
In addition, efforts are being made to introduce film-forming polymer emulsions such as acrylic latex, vinyl acrylic resin, vinyl acetate/ethylene copolymer, silicone/acrylate resin, and styrene/butadiene latex.
It is proving effective.

The microfibrous cellulose that is a feature of the present invention is, for example,
A suspension of about 1 to 10% by weight of fibrous cellulose, obtained by chemically or physically valving using techniques known in the art, is passed through a small diameter orifice to form at least 63,000 p.
Provides high speed with a pressure difference of ai (bond/square inch),
It is possible to use the one described in JP-A-56-100801, which is obtained by a step of causing a cutting action by a physical impact force and a step of stabilizing the suspension by repeating the above steps.

The microscopic fibrous cellulose is thought to be uniformly dispersed in the overcoat coating solution, providing excellent leveling properties through effects such as appropriate thickening and capillary action, and preventing repellency, pinholes, and unevenness. .

Of course, the water resistance seen when adding surfactants,
There was no deterioration in oil resistance or deterioration in coloring sensitivity or printability when pigments were added.

Furthermore, the above effect was not observed in cellulose, which is not processed into fine fibers, such as so-called cellulose powder or microcrystalline cellulose.

In the present invention, the amount of microfibrous cellulose added to the overcoat layer is 0.3% or more, preferably,
0.5 to 30% by weight, particularly preferably 1 to 5% by weight, is good from the viewpoint of prevention effect of repelling/pinhole unevenness, color development sensitivity, and printability.

This is because if it is less than 0.3% by weight, the effect of preventing repellency, pinholes, and unevenness tends to be insufficient. Moreover, if the amount exceeds 30% by weight, heat conduction to the coloring layer is inhibited, which tends to have an adverse effect on coloring sensitivity and printability.

Furthermore, it is preferable to use one or more of a water resistance agent, an ultraviolet absorber, and a mold release agent in combination to impart water resistance and light resistance, and to prevent film separation (blocking) due to adhesion.

Further, in the present invention, the thickness of the dry film of the overcoat layer is preferably 0.5 μm or more, preferably 3 to 12 μm from the viewpoint of chemical resistance and coloring sensitivity. Film thickness is 0
．． If it is thinner than 5 μm, the chemical resistance will not be sufficient, and if it is thinner than 12
If it exceeds μm, coloring sensitivity tends to decrease.

The support to which the heat-sensitive coating liquid is applied is generally paper, but any material such as synthetic paper or synthetic resin film can also be used.

[Example 1] Liquid A and B were ground in separate ball mills for 24 hours, and the resulting liquid was coated on a base paper with a 48 P/m diameter to a coated amount of 5 S'/m after drying. ' and dried at 60''C for 1 minute to prepare heat-sensitive recording paper.

Coating solution C The prepared coating solution C was overcoated on the above heat-sensitive recording paper so that the dry film thickness was 5 μm, and the chemical-resistant heat-sensitive paper was coated with a super calender so that the Beck smoothness was about 400 seconds. Recording paper was made.

[Example 2] D solution D solution was used instead of C solution in Example 1, and the dried film thickness was 5 μm.
A chemical-resistant thermosensitive recording paper was prepared by overcoating the above heat-sensitive recording paper so that it had a Bekk smoothness of about 400 seconds using a super calender.

[Comparative Example 1] A chemical-resistant thermal paper was produced in the same manner as in Example 1 except that the microfibrous cellulose suspension was removed from Solution C.

[Comparative Example 2] A chemical-resistant thermal paper was produced in the same manner as in Solution D of Example 2 except that the microfibrous cellulose suspension was removed.

[Example 3] Diazo developer resistance test@: The chemical-resistant thermal papers obtained in Examples 1 and 2E and Comparative Examples 1 and 2 were tested in a heat-sensitive facsimile tester manufactured by Matsushita Electronic Parts ■.
Applied voltage 16. Color was developed to an optical density of 1.2 at OV and a printing pulse width of 3.3 ms. After overlaying this colored surface with a sheet of diazo photosensitive paper (developer Acti-Tap PD, manufactured by Bunshodo) immediately after processing, the colored surface was left at room temperature for 10 minutes to remove the colored surface due to the fogging phenomenon in the background area. The presence or absence of deterioration in reading was observed. Through the above test, the presence or absence of chemical resistance of the overcoat layer, that is, the degree of film completion can be ascertained.

In particular, when observing blank areas, the presence of repellency, pinholes, and unevenness can be determined from the fact that areas not protected by the film turn black with the diazo developer.

Durability, O, P, Test: The chemical-resistant thermal papers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were similarly colored under the above conditions.

Dioctylphthale-1-(D, 0.P) was attached to the colored area, and fading of the coloring area was observed.

The areas where the film was not formed disappear immediately after being coated, so the presence of repellents, pinholes, and unevenness can be determined.

As a result, in the comparative example, although no fogging phenomenon occurred in the background area caused by the developer for diazo photosensitive paper, black spots indicating the presence of cissing and pinhole unevenness were observed over the entire surface. In addition, it penetrates from I, Jiki, etc., and 0. P causes discoloration of the colored part, and the color completely disappears over time.
The print became illegible.

On the other hand, the product of the present invention not only has no deterioration in legibility caused by the developer for diazo photosensitive paper, but also has almost no black spots indicating the presence of holes, scratches, pinholes, or unevenness, and also has O, There was no fading of the colored part due to P, and the result was completely satisfactory.

Claims (1)

[Claims] A heat-sensitive coloring layer is provided whose main components are a colorless or light-colored dye precursor and a color developer that reacts with the dye precursor when heated, and a film-forming polymer compound is further provided on the heat-sensitive coloring layer. 1. A chemical-resistant heat-sensitive recording sheet having improved chemical resistance, characterized in that the overcoat layer contains microfibrous cellulose in the overcoat layer.