JP2543702B2 - High-quality heat-sensitive recording sheet and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-quality heat-sensitive recording sheet which is remarkably improved in image quality and sensitivity and has an excellent uniform surface gloss or a matte surface.

(Prior Art) Generally, a thermosensitive recording sheet is one in which a thermosensitive coloring layer containing a thermochromic composition as a main component is provided on a support such as paper or film, which is heated by a thermal head, a thermal pen, a laser or the like. By doing so, a color image is recorded. Compared with other recording methods, the thermal recording method has the advantages that recording can be obtained in a short time with a relatively simple device, that there is little noise and environmental pollution, and that the cost is low.
It is widely used in many applications such as facsimiles, recorders, printers, ticket vending machines, and labels.

On the other hand, the demand for heat-sensitive recording sheets suitable for equipment is also increasing due to the variety of equipment and higher quality. For example, in a CRT screen copy printer that can output a gradation image, or a measurement printer or label printer that requires high contrast, excellent image quality (dot reproducibility) is required, and at the same time, the thermal recording sheet Homogeneous luster tends to be preferred. On the other hand, for devices such as facsimiles or general printers that mainly use character images, the legibility of the characters is the main focus, so a thermal recording sheet with low surface gloss and excellent image quality and sensitivity is required. To be done. In addition, the low power consumption and high resolution of devices are common to all devices, and high sensitivity and high image quality are required to support these devices. Furthermore, the appearance is uniform and glossy. It has been desired to select a material having a matte or matte surface depending on the intended use.

Such a heat-sensitive recording sheet is manufactured by applying a heat-sensitive color-forming layer on a support such as a conventional paper, and applying a smoothing treatment such as a super calender to improve surface smoothness and image quality and sensitivity after drying. ing.

(Problems to be Solved by the Invention) However, a thermal recording sheet having high image quality, high sensitivity and uniform surface gloss or a high image quality, high sensitivity and uniform matte depending on such a manufacturing method. It has been difficult to obtain a heat-sensitive recording sheet having an adjusted surface.

Improves surface smoothness and improves contact with the thermal head,
Various methods have been proposed as measures for improving image quality and sensitivity. For example, do Super Calendar processing and change Bekk smoothness.
200 seconds-1000 seconds (Japanese Patent Publication No. 52-20142), a thermal recording layer is provided on top of an undercoat layer containing wax, and surface roughness Rz is obtained by super calendering.
Of 2 μm or less (JP-A-59-204594), and supercalendering using a heated metal roll to make the optical surface roughness Rp of 3.5 μm or less (JP-A-61-2).
37683), or a thermal recording layer is applied by a blade coating method of a bend method and dried to have a surface roughness Ra of 1.2 μm.
There is a method described below (Japanese Patent Laid-Open No. 55-156086).

However, even if these measures are used, sufficient image quality and smoothness for giving sensitivity cannot be obtained yet, and the index for these smoothness still does not sufficiently correspond to image quality.

Many attempts have also been made to improve the appearance of thermal recording sheets. For example, the raw material formulation of the heat-sensitive recording layer for preventing background stains and uneven gloss during calendar processing (Japanese Patent Publication No. 50-14531, Japanese Patent Publication No. 51-5947, Japanese Patent Publication No. 56-46786, Japanese Patent Publication No. 60-64888, etc.) , Or calendar treatment conditions (Japanese Patent Publication No. 59-155094) have been proposed, but smoothing treatment such as calendar treatment eliminates unevenness of the texture of the support or uneven glossiness that may be caused by coating unevenness of the thermal recording layer. However, it was not possible to obtain a heat-sensitive recording sheet having an excellent uniform gloss. On the contrary, in order to obtain a uniform matte surface, a treatment such as calendering or not performing the smoothing treatment is used. However, the heat-sensitive recording sheet obtained by these treatments is used. On the contrary, the smoothness decreased, resulting in poor image quality and sensitivity.

(Means for Solving the Problem) The present inventors have excellent image quality and sensitivity, and
The present invention has been achieved as a result of intensive research to obtain a high-quality heat-sensitive recording sheet having a uniform glossy or matte surface.

The roughness curve and contact rate in the present invention are obtained by the following methods.

Roughness curve: Based on JIS-B-0601, using stylus tip curvature radius 5 μm, measuring needle pressure 4 mN (0.4 gf), scanning speed 0.3 mm /
Seconds, measuring length 2.5mm, cutoff value 0.8mm,
It was recorded on the chart, and Surfcom 1500A manufactured by Tokyo Seimitsu Co., Ltd. was used as a measuring device. An example of the measurement is shown in FIG.

Contact rate: The ratio of the length of a straight line parallel to the center line drawn on the roughness curve (a line such that the areas on both sides of the straight line are equal) to cross the roughness curve. , ...
.., Ln and L are expressed by the following equation.

BEST MODE FOR CARRYING OUT THE INVENTION 1. In one or more heat-sensitive recording layers that develop color on a support by heating, the surface smoothness of the heat-sensitive recording layer is JIS-
From the straight line parallel to the center line in the roughness curve based on the B-0601 method and intersecting the roughness curve at a contact rate of 10%, 1.
A high-quality thermosensitive recording sheet having a smooth surface having a contact rate of 80% or more between a straight line drawn parallel to the center line and a roughness curve on the inside of 5 μm.

2. The contact ratio between the roughness curve and the straight line drawn inside 1.5 μm parallel to the center line from the line that intersects the roughness curve at a contact rate of 10% is
The high-quality heat-sensitive recording sheet as described in 1 above, which has a smooth surface of 90% or more.

3. The high-quality heat-sensitive recording sheet as described in 1 above, wherein the surface of the obtained heat-sensitive recording sheet is matte with a glossiness of 30% or less.

4. When forming the outermost surface layer of a heat-sensitive recording sheet in which a heat-sensitive recording layer that develops color by heating is formed on a support, JIS-B-0
The contact rate with a straight line parallel to the center line of the roughness curve based on the 601 method and that is 90% of the contact rate with the roughness curve is 1.5% on the surface side and parallel to the center line. The outermost surface layer in a wet state (plastic state) was joined to a smooth body surface having the following smooth surface, and dried in the joined state to make the outermost surface layer a dry state (state without plasticity). After that, the outermost surface layer is peeled off from the surface of the smooth body, which is a method for producing a high-quality heat-sensitive recording sheet.

5. The method for producing a high-quality heat-sensitive recording sheet as described in 4 above, wherein the wet state of the outermost surface layer is a semi-dry state.

6. The method for producing a high-quality heat-sensitive recording sheet as described in 4 above, wherein the wet state of the outermost surface layer is a state in which a solvent is applied to a dry surface and re-wet.

7. The high-quality heat-sensitive recording sheet as described in 4 above, wherein the outermost surface layer is in a wet state in which the dry surface is further coated with a heat-sensitive recording layer coating solution or a protective layer coating solution and rewet. Production method.

8. The method for producing a high-quality heat-sensitive recording sheet as described in 4 above, wherein the support is an undercoat paper having an air permeability of 300 seconds or less.

9. The method for producing a high-quality heat-sensitive recording sheet as described in 4 above, wherein the heat-sensitive recording layer comprises a plurality of heat-sensitive recording layers that develop different hues.

Is.

Examples of the support used for the heat-sensitive recording sheet of the present invention include papers such as high-quality paper, single-sided glossy paper, coated paper and synthetic paper, and plastic films such as polyethylene terephthalate, polyethylene and polypropylene.

The thermochromic material used in the present invention includes (1) fluorane-based, triphenylmethane-based, spiropyran-based,
A combination of an auramine-based or phenothiazine-based leuco dye and a developer that reacts with these to develop a color when heated, (2) a combination of resorcin and a nitroso compound to form an oxazine dye, or an azo dye What is formed, (3) what forms an azo dye by a diazonium salt and a coupler, (4) what contains a component in which a compound having a secondary alcoholic hydroxyl group is combined with a metal inorganic salt or a metal acetate salt, (5) Combination of carbohydrate and dehydrating agent, (6) Combination of long-chain fatty acid metal salt and phenolic substance, (7) Combination of organic acid heavy metal salt and alkaline earth metal sulfide, (8) Organic acid Combination of heavy metal salt and organic chelating agent, (9) Combination of heavy metal oxalate and sulfur compound, (10) Fatty acid metal salt and aromatic polyhydroxylation (11) Organic acid noble metal salt and organic polyhydroxy compound, (12) Organic acid noble metal salt and aromatic organic reducing agent, (13) Higher fatty acid heavy metal salt and zinc dialkyldithiocarbamate However, the composition is not limited to these combinations, and any composition that develops color by heating may be used.

Examples of such leuco dyes include 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylphthalide and 3,3-bis (p -Dimethylaminophenyl) -6
-Aminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-nitrophthalide, 3,3-bis (p-dimethylaminophenyl) -4,5,6,7-tetrachlorophthalide, 3-dimethylamino -7-Methylfluorane, 3-
Diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane,
3-N-ethyl-N-pentylamino-6-methyl-7
-Phenylaminofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-phenylaminofluorane, 3-dibutylamino-7-o-chlorophenylaminofluorane, 3-diethylamino-7-o-
Chlorophenylaminofluorane, 3-N-ethyl-N
-P-tolyl-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-
p-n-butylphenylaminofluorane, 3-N-methyl-N-propylamino-6-methyl-7-phenylaminofluorane, 3-dibutylamino-7-o-fluorophenylaminofluorane, 3-diethylamino −
7-trifluoromethylphenylaminofluorane, 3
Examples include -N-ethyl-p-toluidino-7-methylphenylaminofluorane, rhodamine B lactam, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3-benzylspironaphthopyran and the like.

Examples of the developer include 4-phenylphenol, 4-hydroxyacetoquinone, 2,2'-dihydroxydiphenyl, n-butylbis (4-hydroxyphenyl) acetate, methylbis (4-hydroxyphenyl) acetate, iso-butylbis (4-hydroxyphenyl) acetate, 2,2'-methylenebis (4-
Chlorophenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-isopropylidenediphenol (also known as bisphenol A), 4,
4 ',-isopropylidenebis (2-chlorophenol), 4,4'-isopropylidenebis (2-methylphenol), 1,1-bis (4-hydroxyphenyl) -1
-Phenylethane, 1,3-di {2- (4-hydroxyphenyl) -2-propyl} benzene, 4,4'-ethylenebis (2-methylphenol), 4,4'-thiobis (6
-T-butyl-3-methylphenol), resorcyl monobenzoate, 1,1-bis (4-hydroxyphenyl) -cyclohexane, 2,2'-bis (4-hydroxyphenyl) -6-heptane, 4,4 ′ -Cyclohexylidenebis (2-isopropylphenol), 4,4′-dihydroxy-diphenyl sulfone, 4-hydroxy-4 ′
-Iso-propyloxy-diphenyl sulfone, 4,4'-
Dihydroxy-3,3'-diallyldiphenyl sulfone,
Anilide salicylate, novolak type phenol resin, benzoic acid, pt-butylbenzoic acid, o-chlorobenzoic acid,
p-chlorobenzoic acid, dichlorobenzoic acid, trichlorobenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, p-hydroxybenzoic acid benzyl ester, o-
Toluic acid, m-toluic acid, p-toluic acid, phthalic acid,
Isophthalic acid, terephthalic acid, gallic acid, trimellitic acid, salicylic acid, 3-ethylsalicylic acid, 4-ethylsalicylic acid, 3-phenylsalicylic acid, 5-phenylsalicylic acid, 3-hydroxysalicylic acid, 4-hydroxysalicylic acid, 5-hydroxysalicylic acid, 6-hydroxysalicylic acid, dimethyl 4-hydroxyphthalate, α-naphthoic acid, β-naphthoic acid and the like can be mentioned.

In addition to the thermochromic component as described above, a binder such as a natural composition binder such as starches, celluloses, proteins, etc. or a synthetic binder such as polyvinyl alcohol, acrylics, styrenes, etc. as a binder is water-soluble. Alternatively, resins soluble in an organic solvent may be used.

Calcium carbonate is used as a pigment to increase the whiteness and opacity, and to improve the running performance with respect to the thermal head.
Inorganic pigments such as magnesium carbonate, silicic acid, aluminum silicate, barium sulfate, titanium oxide and zinc oxide, or organic pigments such as acrylic and styrene are used.

Further, as an additive, a heat-fusible substance such as paraffin wax, stearic acid amide, ethylene bisstearamide, zinc stearate, calcium stearate, sulfonate such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, or phosphoric acid. A surfactant such as an ester, an ultraviolet absorber such as a benzophenone type or a triazole type or a fluorescent dye can be appropriately used in combination.

Further, a release agent such as a silicone type, a fluorine type, or a funnel oil for improving the release from the smooth body can be preferably used.

The thermosensitive recording layer coating liquid used in the present invention may be prepared by appropriately combining these thermochromic materials, binders, pigments and other additives. For example, the thermochromic material may be contained in an amount of 5 to 50%. , 3-40% binder, 5-60 pigment
%, And other additives are preferably 50% or less.

Further, as the wetting liquid used for the above wetting, water, toluene, mineral spirits, hexane or the like capable of dissolving or wetting the binder is appropriately selected.

The coating liquid used for further coating on the dried heat-sensitive recording layer may be the same composition as the above-mentioned heat-sensitive recording layer coating liquid.
To reduce the amount of thermochromic material and increase the amount of binder component,
Measures such as using a binder with strong storage resistance or adding an ultraviolet absorber are used. On the contrary, when the sensitivity is particularly important, the thermochromic material having high sensitivity is used to increase the ratio, and the adjustment is made as necessary.

The coating amount of the thermal recording layer is not particularly limited, but as a whole including the transfer layer or the rewetting layer,
The dry weight is ² to 25 g / m ² , preferably 4 to 15 g / m ² .

The protective layer containing no thermosensitive coloring material or the layer containing little thermosensitive coloring material preferably has a range of 10 g / m ² or less, particularly 5 g / m ² or less.

As a method for producing the surface of the thermal recording sheet of the present invention,
Although it is a general casting method (a method in which a coating liquid is brought into close contact with a smooth body in a plastic state and then peeled after the plasticity disappears), specifically, the following two methods can be suitably applied.

(Method A) In this method, a transfer layer is formed on the smooth body side, and then the transfer layer is transferred to the support side to obtain a heat-sensitive recording sheet.

More specifically, the transfer layer is applied on a smooth body, and after being semi-dried or dried, it is bonded to the surface of the support or the surface of the heat-sensitive recording layer via an adhesive substance, and then peeled from the surface of the smooth body after bonding. Is the way. At this time, the transfer layer does not necessarily need to contain a thermochromic component when the support is already provided with a thermosensitive layer. Finally, the thermochromic component may be contained in one layer or each layer. If it is necessary to dry the adhesive after joining the smooth surface and the support,
The support is preferably breathable with an air permeability of 300 seconds or less. In the case of an adhesive that does not require drying, a non-breathable film such as a film can be used.

(Method B) A thermosensitive recording layer is applied to a support and joined to a smooth body surface in a semi-dried state, in a state of being dried and then re-wet, or in a state of being applied with a thermosensitive recording layer coating liquid after drying or a protective layer coating liquid, and then joined. It is a method of obtaining a heat-sensitive recording sheet having a smooth surface by drying as it is, and then peeling from the smooth body after drying. Among these methods, from the viewpoint of production stability, it is preferable to coat the heat-sensitive recording layer on the support, dry it once, and then apply the coating solution again. At this time, the joint between the smooth body and the support is preferable. At the inlet, it is preferable to adjust the coating liquid so that the liquid continuously accumulates. In this method, the support is preferably a breathable paper, and the pigment,
An undercoat layer having a binder as a main component and a coating amount of about 3 to 15 g / m ^{2 and} optionally a backcoat layer may be provided.

A sheet is used as the smooth body used in the methods A and B,
Roll-shaped, endless belt-shaped surface JIS-B-0601
Based on the method, the contact rate with a straight line that is parallel to the center line of the roughness curve and that has a contact rate of 90% with the roughness curve and is parallel to the center line at a position of 1.5 μm on the surface side is 20% or less. Preferably, those having a smooth surface of 10% or less are used.

1.5 μm from the straight line where the contact rate is 90% to the surface side
If the straight line drawn in parallel with the center line at the position of the contact point with the roughness curve exceeds 20%, a high quality thermal recording sheet can be obtained even if it is joined to the surface of the smooth body and dried. I can't.

Further, when producing a thermal recording sheet using these smooth bodies, if a one having a glossy surface is desired, a smooth body having a glossy appearance is also used, and if a matte thermal recording sheet is desired. The surface of which is mattized by a chemical treatment or a treatment such as a sandblast method is used, but in any case, it must have the above-mentioned surface smoothness.

As such a material, a plastic film such as PET, PP, PE, a metal, or the like, a surface of which is metal-plated or a resin of which is Teflon or the like is preferably used. Further, in order to improve the releasability, it is preferably treated with silicone, fluorine, a surfactant, wax or the like. In the present invention, a roll-shaped smooth body having a chrome-plated surface is preferable in terms of operability, durability, peelability, and the like, and a chrome-plated surface treated with Teflon is also excellent in peelability.

(Function and effect) As described above, the surface of the thermosensitive recording sheet obtained by drying while being bonded to the smooth body in the wet state has a surface smoothness of the thermosensitive recording layer based on JIS-B-0601 method. Parallel to the center line of the height curve and the contact rate with the roughness curve is 10%
It is possible to make a smooth surface with a contact rate of 80% or more between the straight line drawn parallel to the center line 1.5 μm inward from the straight line intersecting with and the roughness curve. The smoothness to the head is good and the image quality is
It has excellent sensitivity. By using a smooth or glossy surface, it is possible to obtain a heat-sensitive recording sheet having a uniform glossy or matte surface appearance without degrading the image quality and sensitivity of the heat-sensitive recording sheet. .

(Examples) Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the description of these examples.

The measuring method in the examples of the present invention is as follows.

1. Gloss: Murakami Color Research Laboratory Co., Ltd. Glossmeter GM-3 Angle 75 ° 2. Image quality / sensitivity: Using a tester manufactured by Matsushita Electronic Components Co., Ltd. Applied voltage 16.0V Pulse width 1.0-3.4ms The image density was measured with a Macbeth reflection densitometer (RD-914) after the drawing. Further, the dot reproducibility of the image portion was evaluated by visual inspection and an enlarged photograph.

3. Smoothness: Oken type smoothness measuring instrument was used.

4. Appearance: Evaluated by visually observing uneven gloss and background stain.

5. Optical Surface Roughness Rp: A Microtopograph manufactured by Toyo Seiki Seisaku-sho, Ltd. was used.

Measurement conditions: Applied pressure 10kgf / cm ² Sampling time 1
00ms 6. Average wavelength Rλa, centerline average roughness Ra and 10-point average roughness RR
As the value of Z, the value output from the measuring device Surfcom 1500A was used.

Example 1 Liquid A: 10 parts of leuco dye (3-N-ethyl-N-pentylamino-6-methyl-7-phenylaminofluorane: S-205 manufactured by Yamada Chemical Co., Ltd.), P-hydroxybenzoic acid 20 parts of acid benzyl ester, 5 parts of dibenzyl terephthalic acid, 10 parts of zinc stearate, and 30 parts of calcium carbonate are dispersed in a sand grinder so that the average particle diameter is 2 μm or less, and a binder of 20 parts (oxidized starch).
15 parts, PVA 5 parts) was mixed with water to prepare a heat-sensitive layer coating solution having a solid content concentration of 23%.

Using a cast coater as shown in FIG. 1, the above-mentioned solution A was dried with an air knife 3 so that the dry weight was 3 g / m ² on the glossy surface of the flat glossy paper 1 having a weight of 47 g / m ² as a support. Applied. After that, it was passed through a hot air dryer 4 to be dried, and then it was bonded to the smooth surface of the cylinder roll 8 using a press roll 5 having a hardness of 90 °. At this time, the liquid A was supplied from the liquid supply nozzle 6 at the joining inlet of the press roll 5 and the cylinder roll 8 so that the liquid pool was continuously formed. The coating amount of rewetting liquid is 1 g / m as dry weight.
^The press pressure was adjusted to ² (4 g / m ² together with the lower layer). The heat-sensitive recording sheet thus measured and applied is dried by the hot air dryer 9 while being in contact with the smooth surface of the cylinder roll 8, and after drying, the heat-sensitive recording sheet 10 is peeled off from the surface of the cylinder roll 8. Was obtained.

The surface (smooth body surface) of the cylinder roll 8 in this embodiment has a mirror surface that is chrome-plated and buffed. The obtained thermal recording sheet had a contact rate of 90% with a straight line 1.5 μm inward from the straight line having a contact rate of 10% in the roughness curve and the above roughness curve, and was excellent in image quality and sensitivity. Further, the glossiness was 45%, and it had a uniform glossy surface without uneven gloss. Table 1 shows the evaluation results
Shown in

Example 2 A thermosensitive recording sheet was obtained in the same manner as in Example 1 except that a cylinder roll having a matte surface was used as the smooth body. The surface of this cylinder roll is chrome plated, then buffed, and then sandblasted to give a matte surface. The obtained thermosensitive recording sheet had a contact rate of 93% with a straight line within 1.5 μm from the straight line having a contact rate of 10% in the roughness curve and the above roughness curve, and was excellent in image quality and sensitivity. The glossiness was 17%, and it had a uniform matte surface with no uneven gloss. Table 1 shows the evaluation results.

Comparative Example 1 In the same manner as in Example 1, the solution A was dried on the support to give a dry weight of 6 g.
It was coated so as to be / m ² , dried with a hot air dryer, and wound up as it was. Liquid A is further dried on this heat-sensitive recording sheet.
And dried at 2 g / m ² was coated so as to (8 g / m ² in conjunction with lower) hot air dryer. Since the obtained heat-sensitive recording sheet had low smoothness, supercalendering treatment was performed to improve smoothness, but both image quality and sensitivity were insufficient. The gloss level was 28%, and there were background stains and uneven gloss that seemed to be caused by the calendar treatment. The thermal recording sheet had a contact rate of 53% with a straight line within 1.5 μm from the straight line having a contact rate of 10% in the roughness curve and the above roughness curve. Table 1 shows the evaluation results.

Example 3 Solution B (transfer layer coating solution) ... Leuco dye (S-205) 5
Parts, 20 parts of bisphenol A, and 25 parts of ethylene bis-stearamide were dispersed in an attritor so that the average particle size was 2 μm or less, and 30 parts of 10% aqueous PVA and 10% aqueous solution of PVA were used as binders. 70 parts of starch and 40 parts of styrene-maleic acid copolymer emulsion (35% strength) were added. To this mixed solution, 60 parts of a 20% silica dispersion was added as a pigment to prepare a coating liquid having a solid content of 22%.

The solution B was coated on a smooth body having a glossy surface (PET 75 μm thickness: Lumirror manufactured by Toray Industries, Inc.) cut into a B-4 size so as to be 10 g / m ² by WET using a wire bar. After coating, the substrate is made semi-dry with hot air (judged visually and touched), and coated with Liquid A on a glossy paper (47 g / m ^{2 of} tsubo) at a dry weight of 6 g / m ² Was bonded using a rubber roller and dried with the bonding. After drying, the thermal recording paper was obtained by peeling the transfer layer from the film. The resulting thermal recording paper had excellent surface properties and good image quality and sensitivity. The glossiness was 85% and was uniform.

Example 4 The smooth body used in Example 3 was sandblasted to use a smooth body having a matte surface. This smooth body is JIS-
Based on the B-0601 method, the contact rate with a straight line parallel to the center line of the roughness curve and having a contact rate with the roughness curve of 90% is 1.5 μm on the surface side parallel to the center line. It was 15%. Other conditions were the same as in Example 3 to produce a thermosensitive recording sheet. The obtained thermal recording sheet has a gloss of 15
%, The image quality and sensitivity were good.

Comparative Example 2 The smooth body used in Example 3 was sandblasted to use a smooth body having a matte surface. This smooth body is JIS
-Contact rate with a straight line parallel to the center line of the roughness curve based on the B-0601 method and with the roughness curve and a contact rate of 90%, drawn parallel to the center line at a position of 1.5 μm on the surface side Was 43%. Other conditions were the same as in Example 3 to produce a thermosensitive recording sheet. As can be seen from the performance evaluation results of the obtained heat-sensitive recording sheet, it had a uniform matte surface with a gloss of 13%, but there were spots in the transfer layer that seemed to be due to defective peeling, and the image quality and sensitivity Both were slightly inferior.

Example 5 Solution C: Leuco dye 10 parts (S-205), p-hydroxybenzoic acid benzyl ester 25 parts, dibenzyl terephthalate 5 parts, zinc stearate 15 parts, aluminum silicate
30 parts dispersed with a sand grinder so that the average particle size is 2 μm or less, and 20 parts binder (PVA10
And 10 parts of oxidized starch) are mixed with water to obtain a solid content of 22
% Heat-sensitive layer coating liquid was prepared.

This coating liquid C was applied to the glossy side of a single-sided glossy paper (47 g / m ^{2 of} tsubo) so that the dry weight was 7 g / m ² at the coater head 3 of the coater as shown in FIG. Is 50%
The coated surface of the heat-sensitive recording sheet obtained is dried by passing it through a hot air dryer 4 to a certain degree.
Was dried in a state of being bonded to the sheet, and after being dried, it was peeled from the roll to obtain a heat-sensitive recording sheet.

Here, the surface of the cylinder roll 7 is treated with a fluororesin in order to improve the peeling property. Further, the surface temperature of the roll is adjusted to 50 to 60 ° C., and a hot air blower 9 is installed outside the roll to promote drying.

Various evaluations were performed on the heat-sensitive recording sheet thus obtained, and the results are shown in Table 1. As can be seen from the results, the smoothness was 3000 seconds, there was no background fog, and the image quality and sensitivity were excellent.

Example 6 Solution D: (Preparation of coating solution for heat-sensitive recording layer) Leuco Dye PSD-150 (Shin Nisso Kako Co., Ltd.) 10 parts, bisphenol A 30 parts, ethylenebisstearyl amide 10
And calcium stearate 40 parts each have an average particle size of 2
A heat-sensitive recording layer coating liquid D was obtained by mixing 25 parts of a binder (polyvinyl alcohol) dispersed in a sand mill so as to have a thickness of not more than μm and water.

(Formation of thermosensitive recording layer) The coating liquid D thus obtained was coated on a base paper of 60 g / m ^{2 so} as to have a dry coating amount of 6 g / m ² and dried to obtain a thermosensitive recording sheet.

Solution E: (Preparation of coating solution for protective layer) 60 parts of acrylic coating agent (F-846 15% aqueous solution; Showa Denko) and 20 parts of oxidized starch (MS-3600 15% aqueous solution, made by Nippon Food) and 50% clay A protective layer coating liquid E was prepared by mixing 10 parts of the aqueous dispersion, 10 parts of a 30% zinc stearate aqueous dispersion and 1 part of dimethylol urea with water.

The protective layer coating liquid E having the above composition was applied on the recording layer of the heat-sensitive recording sheet obtained as described above so that the coating amount after drying was 3 g / m ^2, and the coated surface was chrome-plated. To the protective layer-covered thermosensitive recording sheet.

 The performance evaluation results of the obtained sheet are shown in Table 1 of the attached sheet.

The heat-sensitive recording sheet thus obtained had little change in optical density in the image area and non-image area with respect to water, alcohol, plasticizer, etc., and was excellent in storability. Moreover, both the image quality and the sensitivity were good.

Example 7 Solution F (black color-developing first layer thermosensitive recording layer component) 10 parts of leuco dye (3-N-methyl-N-cyclohexylamino-6-methyl-7-phenylaminofluorane: Shin Nisso Kako Co., Ltd.) PSD-150), bisphenol A3
Mix 0 parts and 20 parts of zinc stearate with a sand grinder so that the average particle size is 2 μm or less, then mix with 100% aluminum silicate dispersion of 30% concentration.
Part of PVA and 10% aqueous PVA as a binder.
Solution and 70 parts of a 10% aqueous solution of oxidized starch were added to prepare a solution F. The coating solution concentration was set to 20%.

Liquid G (blue color second layer heat-sensitive layer component) 10 parts leuco dye (crystal violet lactone (CV
L)) Bisphenol A 20 parts, 1-hydroxy-2-naphthoic acid phenyl ester (HS-10 manufactured by Dainippon Ink and Chemicals, Inc.)
94) 10 parts, 20 parts of zinc stearate, each having an average particle size of 2 μm
Liquid G was prepared by mixing the following dispersions with a sand grinder, then adding 100 parts of a 40% calcium carbonate dispersion, and further adding 200 parts of a 10% PVA aqueous solution as a binder. In addition, this coating liquid concentration
22%.

Liquid F was coated on a high-quality paper (53 g / m ^{2 of} tsubo) with an air knife coater so that the dry weight was 6 g / m ² , to obtain a black color-developing layer. Next, as the second layer, the liquid G is dried on the first layer by dry weight.
Coating with an air knife coater to 4 g / m ² ,
In the latter half of coating, it was bonded to a chrome-plated metal roll using a press roll in the dry state. This heat-sensitive layer was dried in a state of being bonded to a metal roll, and peeled from the metal roll after drying to obtain a multicolor color heat-sensitive recording paper. The resulting thermal recording paper had a smoothness of 350 seconds and no background fog was observed.

Next, as a blue colored image, applied voltage 12.0 V, pulse width 3.0
Applied voltage 16.0V, pulse width 2.5 as ms and black colored image
As a result of drawing with ms, the blue image density was 0.55, the black image density was 1.37, which was high density, the dot reproducibility was good, and no color mixture was observed.

Comparative Example 3 Liquid H: As a pigment, silicon oxide (Mizukasil P-832:
50 parts by Mizusawa Chemical Co., Ltd. average particle diameter 2.7 μm and organic hollow pigment (Ropaque OP-84J: Nippon Acrylic Chemical Co., Ltd.)
Made average particle size 0.55 μm) 50 parts, and styrene-butadiene copolymer latex as binder (solid content 48%) 30
The parts were mixed to prepare a coating liquid having a solid content concentration of 30% to prepare an undercoat layer coating liquid H liquid. Solution H was prepared under the same conditions as in Comparative Example 1 except that a substrate having a dry weight of 7 g / m ² coated on a high-quality paper of 45 g / m ² was used as a support.

Table 1 shows the performance evaluation results of the obtained sheet.
As can be seen from the result of Behyo 1, the average wavelength is 60
Those having a size of less than μm were excellent in image quality, sensitivity and appearance.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a heat-sensitive recording sheet manufacturing apparatus used in the embodiment of the present invention. FIG. 2 is an explanatory diagram of a roughness curve and a contact rate calculation method.

Claims (9)

(57) [Claims] 1. In one or two or more thermosensitive recording layers that develop color on a support by heating, the surface smoothness of the thermosensitive recording layer is parallel to the center line in the roughness curve based on JIS-B-0601 method. And a smooth surface having a contact rate of 80% or more between the straight line drawn in parallel with the center line 1.5 μm inward from the straight line intersecting the roughness curve with a contact rate of 10%, and High quality thermal recording sheet. 2. From a straight line that intersects the roughness curve at a contact rate of 10%
The high-quality heat-sensitive recording sheet according to claim 1, which is a smooth surface having a contact rate of 90% or more between a straight line drawn in parallel with the center line to the inside of 1.5 μm and the roughness curve. 3. The glossiness of the surface of the obtained thermal recording sheet is 30.
% High-quality thermosensitive recording sheet according to claim 1, wherein the high-quality heat-sensitive recording sheet has a matte shape of not more than%. 4. When forming an outermost surface layer of a heat-sensitive recording sheet having a heat-sensitive recording layer that develops color by heating on a support,
1.5 from the straight line parallel to the center line of the roughness curve based on JIS-B-0601 method and having a contact rate of 90% with the roughness curve to the surface side.
The contact rate with the straight line drawn parallel to the center line at the position of μm is 20
%, The outermost surface layer in a wet state (plastic state) is joined to the surface of a smooth body having a smooth surface of not more than%, and the outermost surface layer is dried in a joined state to give a dry state (state without plasticity). After that, the outermost surface layer is peeled off from the surface of the smooth body. 5. The method for producing a high-quality heat-sensitive recording sheet according to claim 4, wherein the outermost surface layer is in a semi-dry state in a wet state. 6. The method for producing a high-quality heat-sensitive recording sheet according to claim 4, wherein the outermost surface layer is in a wet state in which a solvent is applied to the dried surface and re-wet. . 7. The wet state of the outermost surface layer is a state in which a coating solution for a heat-sensitive recording layer or a coating solution for a protective layer is further applied to a dried surface and re-wetted. A method for producing the described high-quality thermosensitive recording sheet. 8. The method for producing a high-quality heat-sensitive recording sheet according to claim 4, wherein the support is an undercoat paper having an air permeability of 300 seconds or less. 9. The method for producing a high-quality heat-sensitive recording sheet according to claim 4, wherein the heat-sensitive recording layer comprises a plurality of heat-sensitive recording layers which develop different hues.