JPS5814317B2 - electrically sensitive recording paper - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to electrically sensitive recording paper that directly converts electrical signals into visible images, and improves recording quality by making the thickness of layers involved in recording uniform. be.

The electrically sensitive recording paper referred to herein is composed of at least a support, a conductive substance, a heat-sensitive coloring material, and a binder.

In this recording paper, when an electric signal is applied to the recording paper, heat generated in the vicinity of the recording needle causes the thermosensitive coloring material to obtain thermal energy and cause a coloring reaction, thereby producing a visible record.

Similar to this, JP-A-48-101935
There is a bulletin, and a record paper with a recording layer is disclosed on the fibrous sheet.

The recording principle of this is dry, direct recording, and it is characterized by the fact that it does not generate gas or recording dust during recording.

However, there is a drawback that the recording quality is not sufficient, and this is due to the structure of the recording paper.

That is, the support is mostly paper.

Since paper is made of intertwined fibers, its surface is very rough and uneven, so when a conductive substance is coated or deposited on the surface, the amount of the substance deposited is not uniform.

Therefore, when viewed microscopically, the conductivity varies, which has a large effect on recording quality.

Furthermore, if the amount of conductive material adhered to the paper is increased to an extent that does not affect the recording quality, the variation will be relatively reduced, but this will increase the cost and reduce the paper quality.

Therefore, the present invention aims to make the surface of the support made of fibrous material smooth, to make the thickness of the layers involved in recording uniform, to stabilize the recording quality of these recording papers, and to obtain recordings of even higher quality. The purpose is to provide recording paper that can be

That is, the present invention is an electrically sensitive recording paper in which a support is a fibrous sheet whose surface has been smoothed with a smoothing agent or a conductive layer is provided on the sheet, and a conductive recording layer is formed on this support. .

Here, for the fibrous sheet and L, paper or cloth is used.

In addition, as a smoothing agent, a resin binder such as polyvinyl alcohol, hydroxyethyl cellulose, carboxyethyl cellulose, styrene-maleic acid copolymer, or a polymer containing acrylamide, maleic acid, acrylic acid alone or a derivative thereof and water-dispersed emulsion resins such as styrene-butadiene copolymers and aqueous acrylic emulsions.

Also used are water-soluble polymer electrolytes such as sodium borivinyl sulfonate, quaternary ammonium salt of polyesterpyridine, and sodium salt of carboxymethylcellulose.

In addition to the above-mentioned resin binder 2, the smoothing materials include titanium oxide, zinc oxide, white lead, calcium carbonate,
It is preferable to use a white pigment such as zinc sulfide or activated clay in combination.

These pigments are useful not only for whitening the support, but also for preventing the resin binder from shrinking due to volatilization of its solvent, and for smoothing the surface.

When using only the L-paper or resin binder, it is transparent and has a high recording quality, so diazo copies can be made, and the binding between the base paper and the conductive layer or recording layer is improved. effective.

It is preferable that the surface roughness of the fiber or quality sheet smoothed by the above-mentioned smoothing agent be 3 μRz or less in ten-point average roughness according to JIS standard BO601 and 100 or more in Begg value according to JIS standard P8119.

All of the conductive materials used in the present invention have a specific resistance of 102
It is a white or light-colored compound semiconductor made of cuprous iodide, indium oxide, zinc oxide, tin oxide, cuprous thiocyanate, etc. with a resistance of Ωcm or less.

The above binders can be used as the resin binder used for the conductive recording layer and the conductive layer.

Next, heat-sensitive dye leuco compounds that react with coloring agents to form dyes include crystal violet lactone, which is a triphenylmethane dye leuco compound, and leucomalachite green, and 2-dimethylamino-6, which is a fluoran dye leuco compound. -Methylfluorane, 2-diethyl-6,7
-dimethylfluorane, 2-diethylamine-6-ethylaminofluorane, and the like.

In addition, organic acids such as phenolic compounds are suitable as coloring agents that react with the above dyes, specifically 4,4'-
Examples include inbropylidene diphenol, paraphenylphenol, paracresol, 2,5-xynol, paraethylphenol, paraoxybenzoic acid, gallic acid, and salicylic acid.

Next, examples of the present invention will be described.

Comparative Example IA Liquid Cuprous iodide (water content 28% by weight) 3kg Styrene-maleic acid copolymer (20% by weight aqueous solution) (Arakawa Forestry Co., Ltd. KN-333) 100 parts by weight 430g Ammonium carbonate (20% by weight) % aqueous solution) 26 parts by weight Sodium sulfite Trace amount of styrene-butadiene copolymer (SBR latex) (Danbond, Nippon Zeon Co., Ltd., solid content 50% by weight) 172 g Water 600 g With the above composition, attritor (manufactured by Mitsui Miike Manufacturing Co., Ltd.)
The mixture is pulverized and mixed for a minute, and then this liquid is dispersed using a sand grinder (manufactured by Igarashi Kikai Seizo Co., Ltd.) for a processing time of about 5 hr/l to prepare a cuprous iodide dispersion.

This dispersion is a light-colored suspension with cuprous iodide content ranging from 0.1 to
It is dispersed in the liquid as fine particles of 2μ.

B Solution Bisphenol-A 500g Styrene-maleic acid copolymer (20 weight aqueous solution) (Arakawa Forestry Co., Ltd. KN-333) 100g Water 1000g The above mixture was pulverized and mixed in an attritor for 1 hour, and this liquid was roughly mixed. is dispersed with a sand grinder for a processing time of about 1 hr/l to prepare a color former dispersion.

This dispersion is a white suspension with approximately 0.0% bisphenol A content. It is dispersed in the liquid as fine particles of 1μ.

C Solution Blue pressure-sensitive dye Crystal Violet Lactone c Nisso Shoji Co., Ltd. 140g Styrene-butadiene copolymer (20% by weight aqueous solution) (Arakawa Forestry Co., Ltd. KN-533) 140g Borivinyl alcohol (10% by weight solution) 100g Water 500g The above mixture is pulverized and mixed in an attritor for about 45 minutes to obtain a dye dispersion.

Be careful as dispersing this solution for a long time will cause coloring.

Using liquid A whose solid content was adjusted to 45 ± 5% by weight, it was coated onto the base paper using a wire bar adjusted to have an average thickness of 7 to 8μ after drying, and then coated with hot air and a hot roll. Dry to form a conductive layer.

The surface roughness of the base paper used for this was measured using a surface roughness meter (c stock).
Measured with Tokyo Seimitsu, Surfcom 5A), JIS standard B
When the value was calculated using the ten-point average roughness of 0601, it was approximately 10
The roughness was ~15 μRz.

Next, JIS was measured using a Beck smoothness measuring device (manufactured by Tozai Seiki Co., Ltd.).
The smoothness of the base paper was measured according to standard P8119, and the value was about 80 to 90.

The surface resistivity of the conductive layer formed in this way is 1.2 to 1.
．． The value was 5KΩ.

Next, liquids A and B whose solid content was adjusted to 45±5% by weight
A conductive coloring paint is made by mixing the liquid, C liquid, and a resin binder.

Solution A Cuprous iodide dispersion (solid content 42% by weight) 70g Solution B Color former dispersion (solid content 30% by weight) 100g Solution C Dye dispersion (solid content 16% by weight) 50g Styrene-butadiene copolymer (SBR latex) (
Nippon Zeon Co., Ltd. Danbond, solid content 50% by weight)
25g wax dispersion (Repol No. 50) (Daikyo Chemical Co., Ltd. solid content 38M%)
10g water
After drying 50g of this mixture, the average thickness is 2-3μ.
The coating was applied onto the white to light-colored conductive layer using a wire bar adjusted so as to give a recording layer, and dried with hot air and hot rolls to form a recording layer to obtain a recording paper.

The surface resistivity of this recording paper was 1.7 to 1.8 KΩ.

Using this recording paper, attach it to a Tosha fax (Tokyo Aircraft Instrument Co., Ltd.), apply an electric signal, and use a needle diameter of 0.25.
Using a tungsten recording needle of mm, the scanning speed was 0.
When solid recording was performed at 87 m/sec, linear density of 8 l/mm, and stylus pressure of 10 g, blue recording marks were obtained.

However, in this recording mark, there was a minute portion that was not printed in shading or white.

This is because the thickness of the conductive layer is smaller than the unevenness of the base paper, and in the convex parts of the base paper, the fibers are exposed to the surface, and in the concave parts, there is a lot of paint clogging, causing variations in conductivity. ,
Since recording was performed using a needle with a diameter of 0.25121 mm, the recording quality was degraded due to variations in the conductive layer.

Comparative example 2 Mylar film was used as the support.

The surface roughness of this film is expressed as the 10-point average roughness of JIS standard BO601. It was 0.1 μRz or less.

Each of the solutions used in Comparative Example 1 was applied onto this Mylar film.

First, a cuprous iodide dispersion of liquid A is applied using a wire bar adjusted to have an average thickness of 7 to 8 μm, and dried with hot air and hot rolls to form a conductive layer.

This surface resistivity was 1.0 KΩ, and a conductive layer with very stable conductivity was obtained.

Next, the conductive coloring paint used in Comparative Example 1 was applied onto the conductive layer using a wire bar adjusted to have an average thickness of 2 to 3 μm, and dried with hot air and heated rolls to form a recording layer. , a record sheet was obtained.

The surface resistivity of this recording sheet showed a stable value of 1.3 KΩ.

Using this recording sheet, solid recording was performed using a Tosha fax machine under the same conditions as in Comparative Example 1, and blue recording marks were obtained.

This image is extremely clear and of high recording quality, with no areas of shading or blurred print.

This is because the resistance of the conductive layer is very stable.

Example 1 A base paper was used as a support.

The surface roughness of this paper is determined by the average roughness of 10 points.
The value was 15 μRz, and the base value was 80-90.

A 20 weight polyvinyl alcohol aqueous solution as a smoothing agent was applied onto this support using a wire bar adjusted to have an average thickness of about 12μ, dried with hot air and hot rolls, and then applied with a nip pressure of 20kg/cm. Calendered.

The surface roughness of this paper was 2 to 3 μRz on a ten-point average roughness, and the base value was 100 to 120.

Each of the solutions used in Comparative Example 1 was applied onto a base paper made of this treated support and dried.

First, a cuprous iodide dispersion liquid (A liquid) is applied onto the treated base paper using a wire bar adjusted to an average thickness of 7 to 8 μm, and then dried with hot air and hot rolls to form a conductive layer. .

This surface resistivity showed a stable value of conductivity of 1.4KΩ.

Next, the conductive coloring paint used in Comparative Example 1 was applied onto the conductive layer using a wire bar adjusted to have an average thickness of 2 to 3 μm, and dried with hot air and heated rolls to form a recording layer. Formed.

The surface resistivity of this recording paper was a stable value of 1.6 KΩ.

Using this recording paper, solid recording was performed using a Tosha fax machine under the same conditions as in Comparative Example 1, and blue recording marks were obtained.

Although this image has a lower recording density than Comparative Example 2, the density increases as the voltage is increased.

In addition, there were no shading or unprinted areas, and a stable recording quality was obtained.

There was also less dust and sparks.

Example 2 The same paper as in Comparative Example 1 was used as the support.

On this support, 50 g of a 20% by weight styrene-maleic acid copolymer aqueous solution and SBR latex (
A mixed solution of 10 g (solid content 50% by weight) and 40 g of water was coated using a wire bar adjusted to have an average thickness of about 12μ, dried with hot air and hot rolls, and coated at 20ky/c.
Calendering was performed at a nib pressure of m.

The surface roughness of this paper was 3 μRz or less as a ten-point average roughness, and the base value was 250 to 300.

Each of the liquids used in Comparative Example 1 was applied and dried on the base paper, which was the treated support.

First, a cuprous iodide dispersion (solution A) is applied onto the treated high-quality paper using a wire bar adjusted to have an average thickness of 7 to 8μ, and dried with hot air and heated rolls to form a conductive layer. do.

The surface resistivity was a stable electrically conductive value of 1.2 KΩ.

Next, the conductive coloring paint used in Comparative Example 1 was applied onto the conductive layer using a wire bar adjusted to have an average thickness of 2 to 3 μm, and dried with hot air and heated rolls to form a recording layer. Formed.

The surface resistivity Gjl of this recording paper was a stable value of 4KΩ.

When this recording paper was used to record solid images using a Tosha fax machine under the same conditions as in Comparative Example 1, the recording quality was high, with very clear blue images, and almost no odor, dust, or sparks. Furthermore, even when recording was performed at low voltage, stable quality was obtained.

Example 3 The same paper as in Comparative Example 1 was used as the support.

On this support, etherified starch (
A mixed solution was prepared by dispersing 50 g of a 20 wt% aqueous solution of Nippon Star Chemical Co., Ltd. (PIOSTARCH), 100 g of titanium oxide, and 300 g of water using a sand grinder at a processing time of 1 hr/l, and the thickness was adjusted to an average thickness of about 12 μm. After coating with wire bar and drying with hot air and hot roll, 20k
Calendering was carried out using a nib pressure aperture of g/cm.

The surface roughness of this paper was 3 μRz or less in ten-point average roughness, and a support having a very smooth surface with a base value of 500 or more was obtained.

The cuprous iodide 1 dispersion used in the comparative example was coated onto this support using a wire bar adjusted to have an average thickness of 7 to 8μ, and dried with hot air and hot rolls to form a conductive layer. Form.

The surface resistivity of this conductive layer is O. It showed stable conductivity of 9KΩ.

Next, the composition of the conductive recording layer. Nickel myristate 1
0 parts by weight, 10 parts by weight of dimethylglyoxime, 5 parts by weight of fine stainless steel powder, 2 parts by weight of sodium polyvinyl sulfonate, and 8 parts by weight of polyacrylic acid ester, with an average thickness of 2 to 3 μm on the conductive layer. The coating was dried to form a recording layer.

The surface resistivity of this recording paper was a stable value of 1.2KΩ.

When this recording paper was used for solid recording with a Tosha fax machine under the same conditions as in Comparative Example 1, it showed bright pink recording marks and was of high quality with no odor or sparks.

Example 4 Solution D: 100 g of conductive zinc oxide fine powder doped with a small amount of aluminum (manufactured by Hakusui Chemical Co., Ltd.), 100 g of water, and the above mixture was dispersed in an attritor for 20 minutes.

Liquid E Bisphenol A 50g Borivinyl alcohol (10% by weight solution) 20g Water 100g The above formulation was dispersed in an attritor for 1 hour.

F solution Blue pressure sensitive dye, crystal violet lactone
35g Polyvinyl alcohol (10% by weight solution) 25g Water 125g The above formulation is dispersed in an attritor for 30 minutes.

The above-mentioned DI, E liquid, and F liquid are mixed at a weight ratio of 10:4:2, and 20 g of styrene-butadiene copolymer is added to 100 g of this mixed liquid to prepare a conductive coloring paint.

The base paper treated in Example 1 was used as the support, and aluminum was vapor-deposited to a thickness of 1000 Å on the base paper to form a conductive layer.

The surface resistivity of this conductive layer was 2 to 3 Ω.

Furthermore, the thickness of this conductive layer after drying the above paint is
It was coated with a wire bar adjusted to have a thickness of about 10 μm and dried to form a recording layer.

The surface resistivity of this recording paper was a stable value of 2.7 KΩ.

When this recording paper was subjected to solid recording at low voltage using Tone Yafax under the same conditions as in Comparative Example 1, a high-quality record with clear blue color and no odor or sparks was obtained.

Examples 5 to 6 In Example 4, zinc oxide powder was used as the conductive material for the recording layer, but instead of this zinc oxide fine powder, stannic oxide fine powder whose conductivity was increased by a trace amount of antimony dove was used. (Example 5), or using conductive indium oxide fine powder doped with a trace amount of tin (Example 6), Example 4
Recording paper was obtained in the same manner as in Example 4, and solid recording was performed using a Tosha fax machine. As in Example 4, excellent quality paper was obtained.

All of the recording papers produced in the comparative examples and examples described above had good quality in solid recording.

Next, the results of the experiments regarding dot printing are shown in the table.

The GE recording needle for this experiment was 0.25×O. Using a 25 mm shape, dot printing was performed at a voltage of 250 Vpp, and the average density and uniformity determined from the printed area were examined using Sakura Microdenside Make (Konishi Roku Photo Industry Co., Ltd. PDM-5). .

However, in Examples 5 and 6, dot printing was performed at a low voltage of 20 to 60 Vpp because the conductive layer had low resistance.

As is clear from the examples, the effect of the present invention is that the recording quality down to the microscopic range is improved.

The principle is thought to be that recording resistance is made uniform by making the thickness of the conductive recording layer or conductive layer uniform.

That is, microscopic uniformity of the recording resistance contributes to uniformity of generated thermal energy with respect to a constant voltage.

To explain in more detail, when a conductive layer with an average thickness of 7 to 8 μm is provided on a base paper with a ten-point average roughness of 10 to 15 μRz as in Comparative Example 1, an extremely thin portion and a thick portion are formed. When viewed microscopically, the resistance is also non-uniform.

In order to take a more detailed look, if we take a cross-sectional photograph of the comparative example, we can see significant non-uniformity in the thickness of the conductive layer.

The values are tmin 4μ and tmax 20μ, which is a ratio of about 5 times.

Therefore, since the composition of the conductive layer is uniform, the microscopic conductive layer resistance also varies by about five times.

This result appears as shading or white areas when solid printing is performed, and becomes noticeable as a decrease in density or non-uniformity of dots when dot printing is performed.

On the other hand, in the present invention, in order to make the thickness of the conductive layer uniform, as shown in the examples, first a smoothing material is applied onto a base paper having a surface roughness of 10 to 15 μRz on a ten-point average roughness. Then, a conductive layer is formed on top of it.

The surface roughness smoothed in this way becomes a treated base paper with a ten-point average roughness of 3 μRz or less.

If you take a cross-sectional photograph of the conductive layer formed on this, you will see that
The values were tmin 7μ and tmax 10μ, which was much more uniform than the conventional one such as Comparative Example 1.

By treating the surface of the base paper to make it uniform in this way, it has become possible to obtain high and stable recording quality that was previously unobtainable.

Note that using glassine paper, cellophane, plastic film, etc. that has been smoothed in advance as a support can provide uniform recording as in the present invention, but it is less natural as a recording paper, and glassine paper , cellophane has the disadvantage that the support undergoes rapid expansion and contraction during coating.

Next, the evaluation results regarding the uniformity of dot printing listed in the table above will be described.

This uniformity was expressed as a value calculated from minimum dot/maximum dot x 100 (%) by randomly sampling 20 dots from each recording paper on which dots were printed at the above voltage.

As shown in the table, the uniformity of the conventional recording paper shown in Comparative Example 1 was less than about 40%, but the uniformity of the recording paper according to the present invention was more than 80%. In the sensory evaluation, when the uniformity was 80% or more, almost no unevenness was felt.

When using base paper with a surface roughness of 4 to 5 μRz on a ten-point average roughness, it is possible to increase the thickness of the conductive layer or conductive coloring layer to provide uniformity, but the recording paper and L are expensive. Furthermore, when a conductive layer or a conductive color forming layer is formed to the same thickness as in the present invention, the uniformity is 65% and unevenness is also felt.

If a support smoothed to a ten-point average roughness of 3 μRz or less is used, the microscopic resistance value is much more stable than that of conventional recording paper.

It is also possible to obtain a recording paper in which the thickness of the conductive layer or the conductive coloring layer is smaller than that of conventional recording paper.

As described above, according to the present invention, high quality recording can be obtained.

Claims (1)

[Claims] 1. Consists of an inductive recording layer and a support, the conductive recording layer containing a conductive material, a coloring component, and a resin binder, and the support being a fibrous sheet or a conductive layer on the sheet. 1. An electrically sensitive recording paper comprising: the surface of the fibrous sheet is smoothed with a smoothing material to a surface roughness of 3 μRz or less in ten point average roughness. 2. The electrically sensitive recording paper according to claim 1, wherein the smoothing material is a resin binder. 3. The electrosensitive recording paper according to claim 2, wherein the smoothing material contains a white pigment. 4. The electrically sensitive recording paper according to claim 2, wherein the resin binder is selected from the group consisting of water-soluble resins and water-dispersed emulsion resins.