JPS6169490A - Thermal recording method - Google Patents

Abstract

PURPOSE:To ensure a favorable heat-accepting effect and favorable response even to short heat pulses and enable high-speed thermal recording, by enhancing the surface smoothness of a base before smoothening the surface of a recording layer provided on the base. CONSTITUTION:The recording layer comprising thermal color forming components and a binder as primary components is provided on the base, and the surface of the recording layer is smoothened to a smoothness of not lower than 1,100sec (Bekk smoothness) to produce a thermal recording material, on which recording is conducted by impressing thermal signals in the form of short pulses of a pulse width of not larger than 1msec. The recording material may be produced either by providing the recording layer 2 directly on the base1 such as a paper and a resin film, or by providing an intermediate layer 9 of a resin or the like on a base 7 and providing a recording layer 8 thereon. In the case of the recording material comprising the intermediate layer 9, the smoothening treatment thereof can be performed more easily and to a higher extent, as compared with the case where the base consists solely of, for example, a paper.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal recording method, and particularly to a thermal recording method in which recording is performed by applying short pulse thermal signals to a thermal recording medium.

[Conventional technology]

In recent years, facsimile machines, printers, etc. have made remarkable progress, and a wide variety of recording systems have been proposed. Among these, thermal recording methods, so-called heat-sensitive methods, have recently been adopted as recording means in the above-mentioned facsimile machines, printers, etc., partly because the devices or mechanisms are relatively simple. are increasing.

Among such heat-sensitive (recording) methods, methods using a thermal head are attracting particular attention and are increasingly being put into practical use.

The thermal recording method using this thermal head consists of a support l made of paper, plastic, etc., and a thermal recording layer 2 formed by coating or impregnating the support as shown in FIG. Thermal information is applied to the recording paper 3 from the recording head 4 to form a colored image on the recording paper 3.

That is, first, a signal generated from the power supply unit 5 is transmitted to the thermal head 4 via an electric circuit (not shown).

Here, a resistor included in the thermal head 4 generates heat, and the heat is conducted to obtain an image 6 in the thermosensitive recording layer 2 in accordance with the signal.

The advantages of the heat-sensitive recording method explained above are that the primary color recording material is used (re-maintenance is free), that the small amount of recording material is inexpensive, and that it is easy to handle; (1) The device is smaller; (2) the recording operation is so-called non-impact, so noiseless recording is possible; (2) the recording system including the device can be obtained at low cost.

However, on the other hand, the following drawbacks have been pointed out in conventional heat-sensitive recording techniques of this type.

The biggest drawback of currently known thermal recording is that its printing speed is extremely slow compared to other recording methods. The heat pulses used are on the order of IO milliseconds to 20 milliseconds, and even the particularly fast ones are at most 5 to 6 milliseconds. As described above, conventional heat-sensitive recording technology is particularly slow in responding to high-speed recording.

Regarding this, two factors can be pointed out.

First, in the conventional method, heat was not efficiently conducted from the thermal head to the recording paper. In other words, due to the V between the thermal head surface and the surface of the recording paper with which it comes into contact, due to the poor layering properties, there is an air layer between them, which impedes heat transfer, and the heat (energy) is actually applied to the recording paper. The amount is less than a few percent of the amount of heat generated by the thermal head. Therefore, in order to apply the necessary and sufficient amount of heat to the recording paper, it is necessary to increase the time during which the thermal head generates heat (that is, the heat pulse width), or to increase the amount of heat generated by the thermal head itself.

Considering the conduction loss as mentioned above, it was necessary to further increase the amount.

However, this goes against the goal of high-speed recording, has limits in terms of the durability of the thermal head, and unnecessarily increases its power consumption, which is not a preferable measure.

A second problem is that no thermal head has been developed that can withstand on-off operations (rapid temperature changes) of short pulses of high heat. In other words, in order to conduct the necessary and sufficient amount of heat at high speed, it is necessary to generate as much heat as possible in a short time, but there was no thermal head that had sufficient durability for practical use. Due to. In the first place, in order to generate high heat in the thermal head, the power consumption will increase, so taking measures to increase it unnecessarily is
There are limits of course.

As a way to overcome some of the above-mentioned disadvantages, several proposals have been made to increase the smoothness of the surface of thermal recording paper to improve its adhesion to the thermal head.For example, Japanese Patent Publication No. 52-20142 The publication describes that the surface of heat-sensitive recording paper is treated to have a surface smoothness in the range of 200 to 1000 seconds in Bekk smoothness. In addition, the recording paper is 1. For example, in the conventional high speed, 0.05 E/second ~
It was found that the heat pulses (1 millisecond) were completely unresponsive.

In order for the surface of the recording layer of the recording paper to respond sufficiently practically (that is, to develop color accurately) to such high-speed heat pulses of about 1 millisecond or less, the surface of the recording layer of the recording paper must be
As a result of various studies by the present inventors, it has become clear that it is necessary to have a smoothness of 0 or more (Beck's flatness).As a conventional 1 surface smoothing treatment,
When recording paper is created through a step of applying a recording layer A coating material containing a heat-sensitive coloring component to its support and other members (for example, gills) and passing it through a pressure roller whose T11 side has been polished, the number of times it passes between the pressure rollers increases. As the number increases, the surface smoothness increases, but on the other hand, so-called pressure blurring occurs, the background density of the recording paper increases, the contrast with the recorded image formed there decreases, and the single color development sensitivity itself is extremely low. It turned out that this would cause some inconvenience. For the reasons mentioned above, it has also been found that the more highly smooth the surface is desired, the more severe the problem becomes. Therefore, with the conventional method, it is impossible to perform high pi and arresting heat recording without causing pressure burr (or ground force burr).

[Problem that the invention seeks to solve]

Accordingly, a primary object of the present invention is to provide a recording method that is well suited to an unprecedented high-speed thermal recording system.

[Means for solving problems]

The above object is achieved by the present invention as follows.

That is, in the present invention, a recording layer whose basic composition is a thermosensitive color forming component and a binder is provided on a support member, and the surface of the recording layer is further smoothed to a level of 1100 seconds (Beck smoothness) or more. This is a thermal recording method characterized in that recording is performed by applying a short pulse thermal signal of 1 millisecond or less to a thermal recording medium.

[For production]

As explained above, according to various studies conducted by the present inventors, it has been found that, for example, 1 millisecond or less (in particular, 10.05 milliseconds to 1 millisecond ), when using a thermal signal with a short pulse width of It is necessary to take measures to increase the adhesion to the body, and for this purpose, the surface of the recording medium is required to have a high level of smoothness of at least 1100 seconds (Beck smoothness) or higher. In addition, in order to increase the coloring sensitivity due to printing heat, it is known that the density of the coloring component contained in the recording layer needs to be increased.From one or more findings, a recording layer paint containing a coloring component at a high density is used. In order to increase the surface smoothness without causing pressure blur after coating on paper, it is necessary to check the smoothness of the support (e.g. paper) before performing the surface smoothing treatment of the recording layer. It is necessary to increase the

Here, the details of the structure of the recording medium used in the present invention will be explained with reference to the drawings.

In the recording medium used in the present invention, as shown in FIG. 1, a recording layer 2 is provided directly on a support 1 such as paper, resin, or film, or as shown in FIG. It is possible to adopt a configuration in which an intermediate layer 9 made of resin or the like is previously formed on the recording layer 7, and then the recording layer 8 is provided thereon. It should be noted that the structure of the recording medium whose recording layer is used in the present invention, including the intermediate layer 9 as shown in the second figure, can be smoothed more easily and more highly than when the recording layer is made of paper alone. This can be said to be a preferable configuration for the purpose of the invention.

The thermosensitive coloring component contained in the recording layer 2 or 8 described above is usually a combination of a colorless or light-colored coloring compound and a phenolic compound that develops color when it comes into contact with the compound6. Examples of the former include 3.3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone) and 3.3-bis(p-dimethylaminophenyl)phthalide (macalite green lactone). triphenylmethane derivatives, 3-cyclohexylamino-6
-chlorofluoran 3-diethylamino-6-methyl-7-p-nbutylphenylamino-fluoran 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6-methyl-7-7nilinofluoran 3.6- Fluoran derivatives such as bis-(N,N-diethylamino)fluoran, 3.3-bis-(p-diethylaminophenyl)natutalide 3-(3'-methyl-47-diethylaminophenyl)
-3-(3''-methyl-4-per-dimethylaminophenyl)-6(or 7)-nitronaphthalide and other natuthalide derivatives 3-(4'-diethylaminophenyl)-3-(2+-
chlor-4''-dimethylaminophenyl)-7-7zaphthalide 3-(4'-dibenzylamino-2'-methoxyphenyl)-3-(4-dimethylamino-2''-chlorophenyl)-7-7 7 Zaphthalides such as zaftalide, 3-(p-dimethylaminophenyl)-3-(l-methylpyrrol-2-yl)-6-diethylaminophthalide 3-(p-dimethylaminophenyl)-3- (1,2-
Heterocyclic allyldiphenylmethane derivatives cis-3,5-bis-(p-dimethylaminophenyl), such as dimethylindol-3-yl)-5-diethylaminophthalide, etc.
-3,5-bis-(1,2-dimethylindole-3-
) pyromellitic anhydride derivatives such as viromellitide; diphenylmethanemethane derivatives such as phenyl-0-carpoxyphenylhydroxymethane lactone;
A chromogenic lactam compound, exemplified by the lactam of derivative, 9-balanitroanilino-3,6-bis(diethylamino)-9-xanthenyl-orthobenzoic acid.

3.6-bis-(diethylamino)-9-hydroxy-
Chromogenic sultone compounds such as sultone of 9-xanthenoylbenzenesulfonic acid, 1.3.3-)dimethylindolino-8'-methoxybenzopyrylsubirane 1.3.3-)dimethyl-5- Gloroin Dorino-8'
- Color-forming spiropyran compounds such as ethoxyspiran, tris-(
Bis(p-dimethylaminophenyl)methane, a color-forming leukotriphenylmethane compound such as bis-(p-dimethylaminophenyl)p-dimethylamino-〇-carboxyphenylmethane.

Color-forming leukodiphenylmethane compounds such as tryptophan, leucoauramine, etc., 3,7-bis-dimethylamino-1O-7 cetylphenothiazine 2-methyl-3-7minor-7-dimethylamino-1O-
Examples include color-forming acylphenothiazine compounds such as p-methoxyhendiylphenothiazine. Phenolic compounds that react with the above compounds include bisphenol A, 2.2-bis(4-hydroxyphenyl)-
n-hebutane 1,1-bis(4-hydroxyphenyl)
Cyclohexane, α-naphthol, β-naphthol, 4
- Tertiary butylphenol, novolak type phenolic resin, etc. Among these, phenolic compounds having many hydroxyl groups in one molecule are desirable.

As a binder, starch, sodium alginate, gum arabic, dextrin, gelatin, casein, albumin, methylcellulose, ethylcellulose, hydroxyethylcellulose, acrylamide carboxymethylcellulose, cationic starch, dialdehyde starch, polyvinyl alcohol, sodium polyacrylate, polyethylene oxide In addition to water-soluble polymers such as , polyvinylpyrrolidone, polyvinyl methyl ether, and polyvinylethyl ether, single, binary, and triple polymers such as polyvinyl acetate, styrene-butadiene, vinyl chloride-vinylidene chloride, and styrene-acrylonitrile are used. Emulsions of the original photopolymerized polymers can also be used. Furthermore, emulsions of other water-insoluble resins can also be used, and these nibbled type binders and water-soluble resins can also be used in combination. In addition, waxes as a so-called anti-sticking agent to the head, or inorganic pigments as described below can be added for the purpose of improving writing properties and whitening.

For example, talc, natural and synthetic generalites (molecular sieves 3A, 4A, 5A, 13X, etc.), titanium oxide, zinc oxide, kaolin, montmorillonite, magnesium oxide, aluminum oxide, tin oxidized, V
L-drinking magnesium, calcium carbonate, sulfur calcium,
An example is barium sulfate.

Further, the intermediate layer 9, which is provided on the support as necessary, is formed using any of various resins.

The heat-sensitive recording material used in the present invention can be manufactured generally by the following method.

First, the method of surface smoothing treatment is a conventionally well-known method, such as a method of applying a machine calender, a super calender, a gloss calender, etc. When applying a machine calender, a load is applied between rigid rollers with mirror-finished surfaces, and the higher the smoothness required for the object, the greater the load or the more times the object is passed through. .

When the support is paper, it is preferable to perform a smoothing treatment on it in advance as necessary. For example, the initial
It is possible to improve the smoothness to the level of paper (Beck smoothness) of seconds (Beck smoothness). This operation can be performed more easily and to a higher degree when the surface of the paper is coated with resin. By the way, when passed between the same rolls as above, the surface smoothness can be easily improved to 900 seconds (Beck smoothness) after several times.
You can do more than that.

As will be explained in detail later in Examples, in the present invention, the surface smoothness of the support is preferably set to 500 seconds (Beck smoothness) or more in parallel with the treatment of the support. Then, prepare the recording layer paint as follows.

Thoroughly disperse and knead the above-mentioned color-forming compound, binder (additives such as dispersant, antifoaming agent, brightener, etc. may be added from the beginning or during the process), and the solvent. .

Similarly, the phenolic compound, binder, and solvent are sufficiently dispersed and kneaded.

Next, a recording layer paint containing a mixture of the color-forming compound liquid and the 7-propanol compound liquid is applied to the support surface by roll coating.
Bar application, spray application.

After drying one or more of the coatings to be applied by dipping or other techniques.

(Furthermore, a wax liquid or the like may be applied as a protective film.) In the present invention, the same smoothing treatment as described above is performed, but the extent of this smoothing is limited.

1100 seconds (Beck smoothness) or more is required.

Obtaining this level of surface smoothness is relatively easy in the present invention. That is, it is possible to achieve the high level of smoothness described above without applying a large load between the mirror-finished pressure rollers and by passing the rollers several times.

Therefore, in the present invention, the degree of pressure wrinkling of the recording layer due to the above operations is extremely low, and a recording medium that causes no practical problems can be used.

It should be noted here that all smoothness values used in the description of the present invention are expressed in Bekk smoothness.Such Bekk smoothness is based on the test method of Japanese Industrial Standard JIS-PGL19. This is the obtained value.

The recording method of the present invention described above will be explained in more detail with reference to Examples.

The effects of the present invention will be more clearly understood based on the following examples.

Manufacturing example 1 of recording body A color-forming compound liquid was prepared with the following composition.

Next, a phenolic compound was prepared with the following composition.

Each liquid was thoroughly kneaded using a ball mill.

Next, polyethyl acrylate was coated to a film thickness of IIL on a 70 l thick high-quality paper (smoothness: 90 seconds), and this
One pass between mirror-finished stainless steel rollers with a linear pressure of K g/cm resulted in a smooth surface of 1100 seconds. Using this as a support surface, apply the above coloring compound and phenolic compound solution using a coating rod for 5p.
After coating and drying to a film thickness of approximately 20Kg/Cm
The grass was passed a predetermined number of times between mirror-finished stainless steel rollers having a linear pressure of . The background density and surface smoothness (Beck smoothness) of the treated recording paper were as shown in Table 1.

Example 1 Smoothness 1so obtained by surface smoothing treatment obtained in Production Example 1
Printing was performed by applying a thermal head to three types of recording paper: o seconds, 2500 seconds, and 4000 seconds. Printing conditions: head size 0.2mm x 0.2mm, applied energy 30mJ
/mm2.100 psec pulse, 4 pulses/mm. As a result, a clear colored image was formed on each recording paper according to the size of the head without uneven printing (coloring).

Incidentally, the maximum color density was 0.80 at 1 spectral density.

For comparison, a printing test was conducted under the same conditions as described above on a recording paper with a smoothness of 850 seconds obtained in Production Example 1 without surface smoothing treatment.

There were many irregularities in printing (color development), and the spectral density was 0.55 even at the maximum color density region.

Manufacturing Examples 2 to 7 of Recording Materials Paper with a thickness of 65 ml and a weight of 84 g/m2 (smoothness near 5 seconds)
The various resins summarized in Table 2 below are coated to a predetermined thickness,
When these were passed once between mirror-finished stainless steel rollers having a linear pressure of about 20 kg/cm2, the smoothness was as shown in the table.

Next, the same recording layer paint as shown in Production Example 1 was applied to each of them to a thickness of 5 ml using a coating rod, and after drying, each was coated with a mirror-finished stainless steel roller having a linear pressure of about 10 kg/am. I passed it once in between. The surface smoothness (Beck smoothness) and background density (spectral density) of the recording paper after such treatment are as follows.

The results are summarized in Table 2 below.

Examples 2 to 7 Printing was performed by applying a thermal head to each of the recording papers obtained in Production Examples 2 to 7, which had been subjected to surface smoothing treatment.

The printing conditions are; spatula size: 0.2 mm x 0.2 mm.

Applied energy 30 mJ 7 mm 2.500 psec
The pulse was 4iFJmm. As a result, a clear colored image was formed on each recording paper that was consistent with the size of the head and had no uneven printing (color development).

Note that the density of one color image was in the range of O, aO to 0.75 (spectral density). The effects of the present invention described above can be summarized as follows.

■It has extremely good adhesion to the thermal head, so it has better heat reception efficiency than ever before, and responds well to short heat pulses.
High-speed thermal recording is possible.

■It shows practical responsiveness even to short heat pulses of about 1 millisecond or less, and has extremely good color development sensitivity.

(2) Even during high-speed recording, there is no need to significantly increase the amount of heat generated by the thermal head, so the durability of the thermal head can be dramatically improved and consumption and tolerance can be reduced.

■Since a recording medium with excellent surface smoothness is used, there is less wear on the surface that is in contact with the thermal head.

The service life of the thermal head can be extended.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an overview of the thermal recording method of the present invention using a thermal head and an example of the configuration of a thermal recording body used in the present invention, and FIG. FIG. 3 is a schematic cross-sectional view showing another example of the structure of a heat-sensitive recording medium. In the figure, 1, 7---support, 2.8=-recording calendar. 4 = ------- one heat head, 9 □ middle layer. Patent Applicant Canon Co., Ltd. 1st Ward 2nd Ward

Claims (1)

[Claims] For a heat-sensitive recording body formed by providing a recording layer whose basic composition is a heat-sensitive color forming component and a binder on a support member, and further smoothing the surface of the recording layer to a level of 1100 seconds (Beck smoothness) or more, A thermal recording method characterized by recording by applying a short pulse thermal signal of 1 millisecond or less.