JPS63168385A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To improve printing quality and sensitivity without texture fog and further to achieve the advancement of productivity and quality stability, by a method wherein an undercoat paper of not more than 300 seconds in air permeability of paper is coated with an overcoat layer and connected, in a wet state, to a surface of a smooth material to be dried. CONSTITUTION:A liquid prepared by mixing, for instance, leuco dye of lactone series or the like and binder of starch group or the like is mixed with ultrafine silisic anhydride as pigment to prepare a thermal recording layer coat liquid. A thermal recording undercoat paper of not more than 300 seconds in air permeability of paper is obtained by applying this undercoat layer coat liquid on a wood free paper to be dried. The overcoat layer coat liquid is excessively supplied onto this thermal recording layer with a nozzle state coat liquid supplier and a dry coat thickness at a part connected to a surface of a smooth material is so controlled as to become, for instance, 1mum by a press roll pressure. Then, the overcoat layer coat liquid is dried as it is connected with the smooth material and peeled off after drying. Thereby, a thermal recording paper can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording paper which is free from background capri, has significantly improved image quality and sensitivity, and has excellent productivity and quality stability.

(Prior Art) In general, thermosensitive recording paper requires a thermal head,
Colored images can be obtained by heating with a thermal pen, laser, etc. Compared to other recording methods, the thermal recording method has the advantages of being able to obtain records in a short time using relatively simple equipment, generating less noise and environmental pollution, and being inexpensive. ,printer,
It is widely used in many applications such as ticket vending machines and labels.

On the other hand, in order to meet market demands, equipment speeds up, energy consumption is reduced, and recording quality becomes higher.As a result, thermal recording paper with high image quality and high sensitivity characteristics, and also has no capri on the surface appearance, is in high demand. has been done.

Conventionally, such heat-sensitive recording paper is coated with a heat-sensitive coloring layer on a paper support, and after drying is subjected to smoothing treatment using a machine calender, a soot calender, etc. to increase surface smoothness and improve image quality and sensitivity. It is manufactured by straining.

(Problem that the invention seeks to solve) Due to this manufacturing method, there is no background capri.

Moreover, it has been difficult to obtain heat-sensitive recording paper with high image quality and high sensitivity. In order to achieve high sensitivity, a technique that is generally applied is to reduce the dispersed particle size of the components involved in color development and increase the ratio. In order to achieve even higher image quality, strongly process the image using machine calendars, super calendars, etc.
A method of high smoothness is used. However, if you strengthen the calendaring process, scalp capri will occur at the same time.

Also, the problem is that the higher the sensitivity, the more background capri occurs. In addition, as a measure to obtain a highly smooth surface with less capri, the following patent was published (Japanese Patent Laid-Open No. 59-155094), which specified the Shore hardness of the elasticity of the super calender. It is not sufficient to obtain a highly smooth surface free of background caps. Furthermore, various measures have been proposed to give characteristics to the heat-sensitive recording paper itself to reduce the background caps during calendering. For example, hooks are added to the heat-sensitive layer to increase the surface lubricity and suppress the generation of frictional heat (Special Publication No. 5 O-14
531), Adding a layer coated with fine powder of starch or a starch derivative to the heat-sensitive layer (Japanese Unexamined Patent Publication No. 56-46786), Adding ethylene-α-olefin copolymer particles to the heat-sensitive layer Contain (JP-A-60-64
888) There are things, etc.

However, these measures are accompanied by a decrease in sensitivity and shelf life, and the generation of surface capri is unavoidable when achieving a high level of smoothness using methods such as curving or super calendering.

As a method for solving this problem, the present inventors first applied a heat-sensitive layer coating liquid onto a support, as a manufacturing method that eliminates the background capri and significantly improves image quality and sensitivity. A method characterized by joining with (
(Patent Application No. 61-134830) and a method (Patent Application No. 61-254616) which is characterized by continuously causing a pool of coating fluid during bonding, but it is difficult to improve productivity and quality stability. There was a desire for something with even better properties.

(Means for Solving the Problem) The inventors of the present invention aimed to simultaneously solve the conflicting characteristics of such thermal recording paper, such as no background capri and high smoothness, and to smoothen the coating liquid in a wet state. In order to improve productivity and quality stability using a manufacturing method that uses This led to the completion of the present invention and the discovery of nine heat-sensitive recording papers.

That is, the present invention provides a heat-sensitive recording layer containing a heat-sensitive color-forming material, a pigment, and a binder as main components on a paper support. It is applied, bonded to another smooth surface while wet, and dried while bonded.

This invention relates to a heat-sensitive recording paper obtained by peeling a smooth material from an optical surface after drying.

The paper support used in the present invention is preferably a generally widely used high-quality paper, glossy paper, etc., which has high air permeability, for example, an air permeability of 100 seconds or less. In order to improve the coatability of the heat-sensitive recording layer, a base paper may be used which has previously been provided with an undercoat layer. In addition, as the heat-sensitive coloring material used in the present invention, a color developer component such as a lactone-based, fluoran-based, or spiropyran-based leuco dye, a phenol compound, an aromatic carboxylic acid, or a clay acid is added by a known method. Used in combination.

In addition, the binder used in the present invention includes natural composition binders such as denguns, celluloses, and proteins, polyvinyl alcohol, acrylic binders, etc.
Examples include synthetic binders such as styrene, but are not particularly limited to these.

The pigment used in the heat-sensitive recording layer has an oil absorption of 50 d/100 N (according to JIS K5101 method).

The same applies to the following) White or colored ones with an oil absorption capacity of 11 or more are preferably used.
0-210m7), fired Keynes earth (oil absorption 130-1
40d), baked clay (oil absorption 50-60m1), white carden (oil absorption 50-30QmA), fine particulate anhydrous silica (oil absorption 100-3007d), particulate anhydrous aluminum oxide (oil absorption 100-50mJ), Examples include fine particulate titanium oxide (oil absorption 50-120m), light calcium carbonate (oil absorption 50-80TrLl), magnesium carbonate (oil absorption 50-150ml), magnesium aluminate silicate (oil absorption 300-3401d), etc. , but not limited to these.

In addition, in the present invention, the air permeability of the heat-sensitive recording undercoated paper is 30.
If desired, the oil absorption amount can be increased to 50% within the range where it can be maintained for 0 seconds or less.
An inorganic or organic pigment of less than 11 Ll/10011 may be used in combination. Such inorganic pigments include kaolin, clay, calcium carbonate, magnesium carbonate, magnesium oxide, titanium oxide, zinc oxide, aluminum hydroxide, barium sulfate, talc, satin white, calcium sulfate, and silica.

Examples of organic pigments include polystyrene, urea formaldehyde resin 7717 grains, and the like.

The coating liquid used to form the heat-sensitive recording layer used in the present invention contains 3 to 20 vt% of the above-mentioned leuco dye and 5 to 40 vt% of the color developer.
wt%, pigment 10-60 wt%, binder 5-25
vt%, and further add sensitizers, waxes, ultraviolet absorbers, etc. as desired, to a total solid content concentration of 1 using a known method.
It is used as an aqueous dispersion of about 0 to 40 inches. If the leuco dye is less than 3 vt 46, the density of one color will be low, and the leuco dye will be less than 20 vt.
If the amount exceeds t%, the coloring density will not improve even if added, so neither is practical.

Furthermore, if the amount of pigment added is less than 10 wt To, which has an oil absorption amount of less than about 50+14/100Ii, the releasability will be insufficient, which is not preferable, and if it exceeds 60 vt To, dyes and color developers will be removed.

It is undesirable if the amount of binder used becomes too small and the original purpose cannot be achieved.

The dry weight of the coating liquid thus prepared is 2 to 1
01/m', preferably from 3 to 7117 m'', and is dried by a conventional method.The resulting heat-sensitive recording undercoated paper has an air permeability of 300 seconds or less.

The thermal recording paper of the present invention has an overcoat layer on the coating layer of the thermal recording undercoated paper. The coating solution for the overcoat layer is prepared by adding the above-mentioned binder and optionally the above-mentioned heat-sensitive coloring material, pigment, and other additives to a total solids concentration of 10 to 50 wtT.

It is preferably used as a 20 to 30 wt% aqueous solution or dispersion.

Also, the coating amount of the overcoat layer is 0.5 as dry weight.
~1017 m'', particularly 1~51/m'' is preferred.

If it is less than 0.51/m'', the coating process itself is difficult and the surface smoothing effect of the heat-sensitive recording layer is poor.

If it exceeds 1011/m", the distance between the heat source and the heat-sensitive recording layer will be too large when used as a heat-sensitive recording paper, and the color development will be reduced. It has a four-ring, sheet, or endless belt shape and is manufactured from materials with excellent surface smoothness such as metal or plastic film.Furthermore, in order to improve peelability, the joint surface is Heat-sensitive recording paper is obtained by peeling the metal, ceramic fluororesin, and the smooth material after drying. The back coat can be used as appropriate.

(Functions and Effects) The thermal recording paper of the present invention has a smooth overcoat layer on the thermal recording layer, but the air permeability is 300 at the stage of thermal recording undercoat paper before applying the overcoat layer. Since the drying time is less than a second, the water that evaporates when the overcoat layer is applied, the smooth surfaces are bonded together in a wet state, and then dried can be easily evaporated from the paper support side, so that the overcoat layer dries uniformly and the Since it forms a film, the surface of the overcoat peeled off from the surface of the smooth body after drying has an excellent smooth surface, and therefore has excellent sensitivity as a heat-sensitive recording paper.

Examples 1 to 3 Solution A (thermal coloring component): 10 parts of leuco dye (3-N-ethyl-N-intylamino-6-methy) v -7- 7 enylaminofluoran Niyamada Chemical Industry Co., Ltd. S-205), p-hydroxyamne, 20 parts of monozoic acid pennol ester, 5 parts of dibenzyl terephthalic acid, and 20 parts of Zn stearate were each dispersed with a sand grinder so that the average particle size was 2 mm or less, A mixture.

B liquid (binder): PVAlO part, oxidized starch 10
Each part is dissolved and mixed.

A liquid ftC liquid is prepared by mixing liquid A and Bi at a weight ratio of 3:1 after drying. Ultrafine particle anhydrous silica (trade name: Mizukashiru P-832, Mizusawa Chemical Co., Ltd.) is used as a pigment.
Co., Ltd. Oil absorption capacity 15 ON//100, S+) 20
50 was prepared. This undercoat layer coating liquid is 501! /rn'' high-quality paper using an air knife coater to obtain a heat-sensitive recording undercoated paper. The air permeability of the heat-sensitive recording undercoated paper obtained was 250 seconds for the pigment weight concentration of 101, 70 seconds for 301, and 40 seconds for 504.

Overcoat layer coating liquid (coating liquid prepared by mixing and dispersing 30 parts of liquid A, 50 parts of liquid B, and 20 parts of ultrafine anhydrous silica as a pigment in dry weight ratio) f:
An excessive amount of the coating liquid was supplied to a nozzle-shaped coating liquid supply tank, and the pressure of the press roll was applied so that the dry coating thickness was 1 μm at the portion to be bonded to the surface of the smooth body. Next, the overcoat layer coating liquid was dried while being bonded to the smooth body, and after drying, it was peeled off to obtain a heat-sensitive recording paper. The obtained heat-sensitive recording paper had good surface properties (because the releasability was good) and the drying speed was also good at 4 to 2.5 seconds.

Comparative Example 1.2 For the pigment and C liquid used in Examples 1 to 4, an undercoat layer coating liquid was prepared so that the weight ratio of the pigment and CG composition after drying was 5:95 and 70:30. Other conditions were the same as in Examples 1-4.

The air permeability of the heat-sensitive recording undercoated paper was 350 seconds with a pigment weight concentration of 5, and 35 seconds with a pigment weight concentration of 70.

The heat-sensitive recording paper obtained had a pigment weight concentration of 54 in the undercoat layer, and some dents were observed on the surface. This was thought to be because the recessed portion had poor peelability and was left behind on the smooth body side during peeling. Further, the drying speed was slow and required about 4.5 seconds. Furthermore, the heat-sensitive recording paper with an undercoat layer pigment weight concentration of 70 had peeling in some areas.

This is considered to be because the bonding force within the undercoat layer became weaker than the adhesive force between the overcoat layer and the smooth body during peeling.

Examples 4 to 6 A thermosensitive recording layer coating solution was prepared in the same manner as in Example 1, except that the liquid C used in Example 1 and the following pigments were used, and the pigment weight concentration was adjusted to t-40% to prepare a heat-sensitive recording layer coating solution. Obtained recording paper.

Example 4: Keisou± (Product name: Suit Kufrosnijil)
-Manufactured by Nsmanville Oil absorption capacity 125 m//1001)
, Example 5: Ultrafine particle anhydrous silica (trade name Thyroid 2
44: Fuji Deguison Chemical Co., Ltd. oil absorbent 300m//10
0,! i+), Example 6: Needle-shaped calcium carbonate (trade name Karurai) SA: Shiraishi Kogyo Co., Ltd. Board oil amount 60
m/Zoo #) The air permeability of the obtained heat-sensitive recording undercoated paper was 85 seconds in Example 4;
In Example 5, the time was 45 seconds, and in Example 6, it was 70 seconds. The thermal recording paper obtained with each of the pigments used had good releasability, and the results of actual drawings and evaluations by artists showed that the paper was very good, with no missing spots and excellent sensitivity contrast. .

Comparative example 3.4 I lost my thermal recording paper.

Comparative example 3: Kaolin (trade name Astratulite: manufactured by Georgia Kaolin Co., Ltd., oil absorption 40 m//Zoo, 9), Comparative example 4: JI calcium carbonate (trade name Koskaronna 15)
0〇Sankyo Ellipse Co., Ltd. Board oil amount 28y,,'toolI
) The air permeability of the thermal recording undercoated paper was 360 seconds in Comparative Example 3 and 400 seconds in Comparative Example 4, exceeding 300 seconds. .

Procedural amendment July 20, 1986

Claims (1)

[Scope of Claims] 1. An overcoat layer is applied to a heat-sensitive recording undercoated paper with an air permeability of 300 seconds or less, which has a heat-sensitive recording layer mainly composed of a heat-sensitive coloring material, a pigment, and a binder on a paper support. A thermosensitive recording paper obtained by applying a liquid, bonding it to the surface of another smooth material in a wet state, drying it while remaining bonded, and peeling it off from the surface of the smooth material after drying. 2. The oil absorption amount of the pigment contained in the heat-sensitive recording layer is 50ml.
The heat-sensitive recording paper according to claim 1, wherein the thermal recording paper has a weight concentration of 10 to 60%.