JPS5927718B2 - heat sensitive recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording sheet, and more specifically, the present invention relates to a heat-sensitive recording sheet, which contains as main components a normally colorless or slightly pale color-forming substance and an organic acidic substance capable of causing the color-forming substance to develop color when heated; The present invention relates to a heat-sensitive recording sheet in which a heat-sensitive layer containing a specific wax is provided on a support.

Recently, with social demands such as an increase in the amount of information, resource saving, labor saving, pollution-free, etc., various recording methods have been put to practical use and improved in the field of information recording.

Among them, the thermal recording method has the following advantages: (i) It uses primary color development, so there is no need for a developing process; (I) The device is easy to assemble and maintain; the thermal recording sheet has a feel similar to plain paper and is relatively inexpensive;
For this reason, it has been put to practical use in the fields of computer output, printers such as calculators, recorders of medical measuring machines, facsimiles, automatic ticket vending machines, thermal copying, etc. Heat-sensitive recording sheets used in such applications are, for example, disclosed in Japanese Patent Publication No. 43-4160.
However, these heat-sensitive recording sheets still have the following drawbacks.

That is, first, because the thermal responsiveness is low, sufficient recording density cannot be obtained as recording speed increases.

Second, during recording, the heat-sensitive composition melts and sticks to the thermal pen or thermal head (statesking), causing inconvenience in paper feeding, or the sticky substance is transferred to the recording paper, causing a trailing phenomenon. Furthermore, a phenomenon occurs in which sticky matter accumulates, lowering the recording density and making the recording unclear. These characteristics are called head matching, and are very important when considering heat-sensitive recording sheets.

However, attempts to improve these characteristics have been made, for example, in Japanese Patent Application Laid-open No. 48-19231 and Japanese Patent Publication No. 51-27599.
It is stated in the issue bulletin etc. In other words, Japanese Patent Application Laid-Open No. 1973-
Publication No. 19231 states that if a wax having a melting point of 40 to 100° C. is used as a carrier, the thermal response can be improved. Japanese Patent Publication No. 51-27599 describes that thermal responsiveness and thermal head adhesion can be improved by using a higher fatty acid amide and a petroleum wax in combination.

However, the current situation is that, with the attempts shown in these documents, it is not possible to obtain a sufficiently satisfactory heat-sensitive recording sheet.

In other words, recording fidelity during high-speed recording with thermal pen recorders, which have recently been changing from metal rod pens used in electrocardiographs to chipped pens made of thermal head type resistors, and gas Regarding the blurring of images due to the adhesion of particles, the actual situation is that the techniques described in such documents alone cannot provide sufficiently satisfactory results. In view of the current situation, the present inventors have repeatedly researched and considered heat-sensitive recording sheets that can be widely used in thermal printers, thermal pen recorders, etc., and have found that a color-forming substance and an organic material capable of coloring when heated. According to the heating layer, which has an acidic substance (color developer) as its main component and adds a specific wax to it,
It has been found that the above drawbacks can be overcome. The present invention has been completed based on this. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-sensitive recording sheet with excellent thermal responsiveness and high recording density.

Another object of the present invention is to provide a heat-sensitive recording sheet that can provide sufficiently clear images even during high-speed recording. Still another object of the present invention is to provide a heat-sensitive recording sheet that does not have the disadvantage that the heat-sensitive material melts and sticks to a thermal head during recording. Still another object of the present invention is to provide a heat-sensitive recording sheet that does not change even after long-term maintenance. That is, the present invention provides a heat-sensitive layer containing as main components a usually colorless or slightly light-colored color-forming substance and an organic acidic substance capable of coloring when heated, which is provided on a support. The heat-sensitive layer contains at least one kind selected from a condensate of a higher fatty acid amide and formaldehyde and a condensate of a higher fatty acid and ethylenediamine, and at least one kind chosen from a vegetable wax and a mineral wax. It is a heat-sensitive recording sheet.

The present invention will be explained in more detail below.

As described above, the heat-sensitive recording sheet according to the present invention is one in which a heat-sensitive layer having a specific composition is provided on a support (paper, synthetic paper, synthetic resin film, metal laminate paper, etc.). Here, the heat-sensitive layer contains at least one type of wax (component C) selected from the group consisting of a condensate of higher fatty acid amide and formaldehyde and a condensate of higher fatty acid and ethylenediamine, so that the heat-sensitive layer is This makes it possible to obtain high recording density with excellent performance.

However, if component C is simply blended with a color-forming substance (component A) and an organic acidic substance (component B) that can make this color-forming substance develop color when heated, it is difficult to sufficiently improve the adhesion to hot pens and thermal heads. I can't. However, when at least one type of wax (component D) selected from the group consisting of vegetable waxes and mineral waxes is added, the adhesion to the head and the abrasion of the thermal pen or thermal head are significantly improved. Become so.

In this case, the use of petroleum wax such as polyethylene, polypropylene, or paraffin wax is undesirable because it tends to stick to the head and, therefore, increases gas adhesion. Component C (wax selected from a condensate of higher fatty acid amide and formaldehyde and a condensate of higher fatty acid and ethylenediamine) includes condensation of stearic acid amide and formaldehyde -▼', and has a melting point of 80 to 150. It is not limited to these as long as it is at ℃.

Ingredient D (wax selected from vegetable waxes and mineral waxes) is extracted directly from plants, such as carnauba wax, sugarcane wax, and cotton wax, or from brown coal produced by decomposing plant substances. Examples include montan wax and their modified products. In the present invention, the normally colorless or slightly light-colored color-forming substances (component A) include leuco substances such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran. 3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide 3,
3-bis(p-dimethylaminophenyl)phthalide 3,
3-bis(p-dimethylaminophenyl)-6-diethylaminophthalide 3,3-bis(p-dimethylaminophenyl)-6-chlorophthalide 3-(N-p-tolyl-
N-ethylamino)-6-methyl-JYo-iN-phenylamino)fluoran 3-diethylamino-J-[chlorofluoranbenzoylleucomethylene 6''-chloro-8'-methoxy-benzoindo 1j nopyrylospirane 6 '-Bromo-8'-methoxybenzoindolinopyrillospiran 2-[3,6-bis(diethylamino)
Examples include, but are not limited to, -9-(0-chloroanilino)xanthyl]benzoic acid lactam 2-{N-(3'-trifluoromethylphenyl)amino}-6-diethylaminofluorane. .

Examples of organic acidic substances (component B) include α-naphthol, β-naphthol, 4-t-butylfuenol, 4
-t-octylphenol, 4-phenylphenol,
2,2-bis(p-hydroxyphenyl)propane, 2
, 2-bis(p-hydroxyphenyl)butane, 4,4
'-Cyclohexylidene diphenol, 2,2-bis(
Examples include 2,5-diprom-4-hydroxyphenyl)propane, 4,4'-isopropylidenebis(2-t-butylphenol), and 2,2-methylenebis(4-chlorophenol). It is not limited.

In order to actually produce the heat-sensitive recording sheet according to the present invention, component A, component B, component C, component D, and inorganic fillers (kaolin, calcium carbonate, etc.) may be used alone or in combination with components other than A, and polyvinyl A protective colloid substance such as alcohol, a surfactant, etc. are added, and the mixture is dispersed using a dispersing machine such as a pole mill, an attritor, or a sand mill, and if necessary, a binder is further added to prepare a heat-sensitive layer forming liquid.

Further, an antifoaming agent, a wetting agent, an organic pigment, a crosslinking agent, etc. may be added to this forming liquid in order to improve coating properties. In this case, the blending amount of component C and component D is 0.1 to 5.0 times the weight of component A, preferably 0.2.
3.0 times by weight, and component D is 0.2 to 6.0 times by weight, preferably 0.2 to 4.0 times by weight. In addition, component C is a condensate of higher fatty acid amide and formaldehyde,
One type of wax selected from condensates of higher fatty acids and ethylenediamine may be used, or two or more types may be used in combination. Similarly, component D may be one type of wax selected from vegetable waxes and mineral waxes, or two or more types may be used in combination. Next, this heat-sensitive layer forming liquid may be applied onto a support so that the solid content becomes 4 to 10 y/nl and dried.

As described above, the heat-sensitive recording sheet of the present invention is not simply an accumulation of the effects of the materials constituting the heat-sensitive layer;
A synergistic effect appears and the intended purpose is achieved.

Example 1 A mixture consisting of the following formulation was ground in a magnetic ball mill for one day to produce liquids [A] and [E].

[A] Liquid Composition A mixture consisting of the following formulations was ground in an experimental attritor for 2 hours to produce liquids [B], [C], and [D].

Next, these solutions [A] to [E] and a 20% polyvinyl alcohol aqueous solution (manufactured by Kuraray Co., Ltd., Poval 205) were mixed according to the following formulation to prepare a heat-sensitive layer forming liquid, and this was applied to commercially available high-quality paper ( 53r/a) FlCl dry solid content is 7-8
V/d, it was coated with a wire bar, dried, and then surface treated with a calender to give a base smoothness of 200 to 400 seconds to prepare a heat-sensitive recording sheet.

The test results of this heat-sensitive recording sheet are shown in Table-1.

As is clear from Table 1, this thermosensitive recording sheet has high thermal responsiveness and is free from states king, gas adhesion, and trailing phenomena.
It was recognized that it has excellent head matching properties with no ghosting. The test method was as follows.

(1) Thermal response was determined to be 2.0! using a thermal tilt tester (manufactured by Toyo Seiki Co., Ltd.) with a hot iron piece controlled at a constant temperature. /C
The color was developed by contacting with a pressure of
The temperature at which 0 was obtained is shown as the thermal response.

Therefore, those with lower temperatures have better thermal responsiveness. (2) For States King, solid printing was performed using the full width of the thermal head, and gas adhesion, trailing, ghosting, and recording clarity were compared and evaluated by running 20 sheets through the Institute of Image Electronics Engineers XL2 facsimile test chart.

(3) Recording density was measured using a Maghes densitometer for the solid portion of the recorded image on the above chart.

Example 2 A mixture consisting of the following formulation was placed in an experimental attritor.
A liquid [C-D] was prepared by grinding for a period of time.

This [CD] solution, [A] solution and [B] solution of Example 1,
[E] Solution and 20% polyvinyl alcohol aqueous solution were mixed according to the following recipe to prepare a heat-sensitive layer forming solution, and a heat-sensitive recording sheet was prepared in the same manner as before.The measurement results are shown in Table 1. It was found to be an excellent heat-sensitive recording sheet. Comparative Example A mixture consisting of the following formulation was pulverized for 2 hours using an experimental attritor to create [C] night.

[C] Liquid composition Using this CCC liquid, [A] liquid of Example 1, and [E], a heat-sensitive layer forming liquid was prepared using the following formulation [B] liquid, 20 (I) polyvinyl alcohol aqueous solution 115y. A thermosensitive recording sheet was prepared in the same manner as in Example 1.

The test results are shown in Table 1. Comparative Example 2-9 A heat-sensitive layer forming liquid was prepared in the same manner as in Example 1 except that the waxes (component C and/or component D) were changed, and seven types of comparative heat-sensitive recording sheets were created.

Claims (1)

[Claims] 1. A normally colorless or slightly light-colored color-forming substance on a support;
A heat-sensitive layer containing as a main component an organic acidic substance capable of coloring the color-forming substance when heated is provided, and the heat-sensitive layer contains a condensate of higher fatty acid amide and formaldehyde, and a condensate of higher fatty acid and ethylenediamine. 1. A heat-sensitive recording sheet comprising at least one kind selected from condensates of the following, and at least one kind chosen from vegetable waxes and mineral waxes. 2 The content of the wax selected from the condensate of higher fatty acid amide and formaldehyde and the condensate of higher fatty acid and ethylenediamine is 0.1 to 5 of the amount of the color-forming substance.
．． The heat-sensitive recording sheet according to claim 1, which has a weight of 0 times. 3. The content of wax selected from vegetable wax and mineral wax is 0.2 to 6.0 of the amount of color-forming substance.
The heat-sensitive recording sheet according to claim 1, which is double the weight.