JPS61274988A - Thermal copy sheet - Google Patents

Abstract

PURPOSE:To prevent the background color formation of thermal paper or the formation of a color due to a hot solvent other than at the time of recording, by separately applying a dye precursor being a thermal color-forming component and a coupler thereof to recording paper being a receiving sheet and a transfer sheet. CONSTITUTION:When a dye precursor and a coupler are applied as indivisual and separate paints, the possibility of the color formation of the paints due to the org. solvents of the paint comprising the mixture of both paints is eliminated and a paint component selection range becomes wide and the paint suitable for spot coating can be obtained. Therefore, the generation of strain and wrinkles due to the application of the paint containing the org. solvent to a paper base material can be reduced or prevented. The transfer layer of the transfer sheet mount to a thermal printer is mutually contacted with the thermal layer of thermal recording paper in the printer and the transfer layer is thermally plasticized or melted by the heating of the thermal heat positioned in the back side of the transfer layer to be transferred to the thermal layer and the dye precursor in the thermal layer generates a color by the transferred coupler to make it possible thermal recording on the thermal recording paper.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a thermal copying sheet that transfers a color developer layer to a dye precursor layer by heating to form a colored hue on the surface of the dye precursor layer. .

(Prior art and its problems) The main thermal recording methods currently in practical use are (a) a method using thermal paper coated with an electron-donating dye precursor and a color developer as an aqueous dispersion paint; (a) A method of transferring and recording onto plain paper using a thermal transfer ribbon. In addition, for multicolor color development, (a) multicolor heat sensitives with different color hues depending on the temperature are used, and the thermal head heating temperature (heating amount) is controlled and adjusted. (a) Using a thermal ribbon on which a pattern of several different hues of thermal transfer ink, generally black and red, or subtractive three-primary colors cyan, magenta, and yellow, is applied at regular intervals; , a method is used in which the ribbon feeding mechanism is controlled to select the position of the transfer ribbon and the transfer hue is selected.

When using self-coloring thermal paper, thermal paper is a recording paper that is entirely coated with a water-based paint made by dispersing and mixing a dye precursor and a color developer in an aqueous system, and can be colored at any time by external factors such as heat or organic solvents. However, there is a risk that the quality may deteriorate due to color development over time. This becomes a problem especially when the thermal sensitivity is high, and the coloring ability remains even after recording, and the recorded content can be changed over several times. Multicolor thermal paper is a thermal paper that is coated with a layer of thermal paints with different coloring temperatures, and the coloring hue can be selected depending on the thermal coloring temperature.In order to select the coloring hue, a special thermal head heating temperature can be controlled and varied. Not only is this mechanism necessary for thermal printers, but if you select a hue that develops at a higher temperature, the color becomes muddy due to subtractive color mixing with the hue that develops at a lower temperature, and low-temperature colors appear around the high-temperature coloring area. There is. Even though it is called multicolor, the practical limit is about two colors.

When using a two-way thermal transfer ribbon, it is possible to use plain paper as the paper, and there is no unnecessary color development other than during recording, and there is an advantage that there is a great degree of freedom in selecting the hue of the ink of the transfer ribbon. . However, transfer ribbons are usually expensive and cannot be transferred many times, and depending on the printed pattern, many parts of the ribbon go unused and are used up, resulting in waste. Furthermore, when performing multicolor recording, inks of different hues are coated in a pattern at regular intervals with an area ratio that takes the frequency of use into consideration, but since the frequency of use is not necessarily determined, the ink remains unused and used up. In addition, in order to select the ink hue, a special transfer ribbon feeding mechanism is required that can control the feeding of the transfer ribbon and select the ribbon position.

Now, when applying thermal recording to a form, the position where recording is required and its hue are often determined at the form design stage, and thermal recording is required at any position on the paper with any hue. is rare. Therefore, specifications can be met by partially spot-coating a heat-sensitive paint that exhibits a predetermined thermal coloring hue to a predetermined position determined by the form design, but self-coloring heat-sensitive paints can only be adjusted as water-based paints. Therefore, it is difficult to spot-coat a water-based paint without causing wrinkles, and it has not been put into practical use.

(Means for Solving the Problems) An object of the present invention is to provide a thermal copying sheet that does not have the above-mentioned drawbacks associated with conventional thermal transfer color forming types.

According to the proposal of the present invention, the object is to record a heat-sensitive recording material using a colorless or light-colored electron-donating dye precursor and an electron-accepting color developer that reacts with the dye precursor to develop color when heated, as heat-sensitive coloring components. In the system, a recording paper is coated with a heat-sensitive color-receiving layer containing a dye precursor as a component on a predetermined portion of the surface that requires heat-sensitive recording, and a color developer layer that has heat-sensitive transfer or heat-transfer properties is separate from this. The color developer is prepared by coating the smooth surface of a sheet with a smooth surface, and then during recording, or after the two coated surfaces are brought into contact in advance, heat from a thermal head located on the non-coated surface of the transfer sheet is applied to the developer. This can be achieved by transferring to recording paper and causing a thermal reaction.
The transfer sheet can be in the form of a ribbon or a sheet.

(Structure and operation of the invention) The present invention is constituted by the following items.

(a) Unless the dye precursor and color developer, which are the basic components of thermal coloring, are applied separately to the thermal recording paper and the thermal transfer sheet, and the coated surfaces of the thermal recording paper and the thermal transfer sheet are not brought into contact with each other, thermal coloring is possible. It did not indicate gender.

This can be expected to improve background color development, essential interpretation of fog, and production efficiency through high-temperature drying of paint.

(b) Since the dye precursor and color developer are applied as separate paints, there is no fear of paint color development due to organic solvents in paints that are a mixture of the two, and the range of paint component selection is widened, making it suitable for spot coating. We were able to create a paint with a suitable formulation. As a result, it is possible to reduce or prevent the occurrence of distortions and wrinkles caused by the coating material containing the solvent on the paper base material.

(1) The dye precursor is applied to a predetermined area of the thermal recording paper, and the coloring hue can be specified on the thermal recording paper side by selecting the dye precursor in the coating area, reducing the area to be coated with expensive dye precursors. can.

(1) If the color developer is applied to the entire back surface of the transfer sheet, there is no need to align the form and the transfer sheet during thermal recording.

(E) Thermosensitive recording paper uses a paper base material or a plastic film base material such as synthetic paper, and one side of the paper is coated with a dye precursor and a filler that improves thermal coloring efficiency, and a binder to fix these on the paper. It is constructed by applying a heat-sensitive recording layer consisting of an agent to a predetermined portion. By appropriately selecting the dye depending on the area to which the recording layer is applied, it is possible to produce heat-sensitive form paper suitable for the intended use.

(Power) The transfer sheet uses a thin and highly smooth plastic film base material or paper base material such as polyester film or capacitor paper, and the smooth surface is coated with a color developer and a sensitizer to improve heat sensitivity. It is constructed by applying a heat-sensitive transfer layer that is fixed onto the paper and includes a binder made of a thermoplastic material that efficiently performs thermal transfer.

(g) The transfer layer of the transfer sheet attached to the thermal printer and the heat-sensitive layer of the heat-sensitive recording paper are brought into contact with each other in the printer, and the transfer layer is thermoplasticized on top of the heat-sensitive layer by heating from the thermal head located on the back side of the transfer layer. Alternatively, the dye precursor in the heat-sensitive layer is thermally fused and transferred or transferred, and the dye precursor in the heat-sensitive layer is thermally colored by the transferred color developer, thereby allowing thermal recording to be performed on a thermal recording paper.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a thermal transfer recording method using a conventionally known thermal printer, in which a thermal transfer ribbon 2 and a recording paper 3 are used as recording media, and the transfer ink layer of the thermal transfer ribbon 2 is heated by a thermal head 1. A general method of transferring or transferring onto recording paper 3 is shown.

FIG. 2 is a schematic diagram of the method of use in the thermal printer of the present invention, in which a commonly used thermal printer is used as is, and the thermal transfer ribbon 2 of the present invention is replaced with the thermal transfer ribbon 2 shown in FIG. The difference is that the sheet 20 is used, and a special recording paper 30 coated with a dye precursor is newly used in place of the plain paper of the recording paper 3.

FIG. 3 shows a schematic structural diagram of a thermal copying sheet of the present invention.

Figure 4 shows that the transfer sheet 2 is heated by the thermal head 1.
This shows a state in which the color developer No. 0 and the dye precursor of the recording paper 30 are melted and mixed. FIG. 5 shows the state in which the fused mixture has been transformed into a dye-forming body 9 by heating of the thermal head. FIG. 6 shows the state in which the transfer sheet 20 is peeled off after thermal recording, and due to the difference in adhesiveness (affinity) of the dye coloring material 9, the dye coloring material 9 remains on the recording paper 30, indicating that recording has been completed. It shows. As seen in FIGS. 3 to 6, the present invention uses a transfer sheet 20 and a recording paper 30.
A thermal copying sheet K is provided, which is constituted by transferring a color developer of 0 to a recording sheet 30, mixing with a dye precursor to develop color 8, and leaving a dye coloring material 9 on a receiving sheet.

The recording paper 30, which is a receiving sheet used in the present invention, is
As shown in FIGS. 3 to 6, a dye precursor receiving layer 6 is provided on a receiving sheet base 7.

The receiving sheet substrate 7 used in the present invention is paper substrates such as high-quality paper and processed paper such as art paper and coated paper in order to give the feel of plain paper as recording paper or to enhance the design effect of the heat-sensitive recording layer. A base material is preferred, and it is also possible to use a special base material such as synthetic paper depending on the purpose.

The dye precursor receiving layer 6 contains a dye precursor that reacts with a color developer to form a color when heated, and when thermal recording is performed in contact with the transfer layer of the transfer sheet 20, the dye precursor receiving layer 6 is thermally transferred or transferred from the transfer sheet 20. It must be able to receive a transfer layer containing a color developer that is thermally transferred, develop color by heat, and stably retain the color components developed by heat when the transfer sheet is peeled off. In order to increase the efficiency of thermal color development, it is necessary to increase the contact between the dye precursor and the color developer and the probability of thermal reaction, so that the dye precursor in the receiving layer is retained on the surface of the recording paper 30 without penetrating into the base material. It is preferable. Considering that a paper base material is used as the recording paper 30, a diameter of 0.5 is required to prevent penetration into the paper base material.
It is preferable to coat the surface of the base material 7 as particles of about 10/-, more preferably about 1-77. In addition, it is required to efficiently transfer and receive the color developer transfer layer 5, and an oil absorbing agent that increases color development efficiency by absorbing and adsorbing the color developer and the dye precursor/color developer melt mixture that melts during thermal recording. is used. Synthetic non-Ia pigments or mineral pigments can be used as oil-absorbing agents, including calcium carbonate, titanium dioxide, silica, clay, talc, kaolin, and the like. It is also effective to absorb and adsorb the dye precursor into an oil-absorbing agent in advance before applying the dye precursor. Therefore, the dye precursor receiving layer 6 consists of a dye precursor and an oil-absorbing agent, or an oil-absorbing agent that has absorbed and adsorbed the dye precursor, and a binder (a water-soluble polymer such as PVA) for binding these onto the paper base material. ), but additives such as sensitizers and storage stabilizers can be used in combination with this.

The heat-sensitive transfer layer 5 contains a color developer that causes the dye precursor to react and develop color when heated, and when thermal recording is performed, the heat-sensitive transfer layer 5 must efficiently develop color from the dye precursor.

It is also required to play a role as a heat transfer layer that transfers heat applied from the transfer sheet base material 4 side to the heat-sensitive receiving layer 6. For this purpose, both the transfer sheet base material 4 and the thermal transfer WJ5 need to have high smoothness and uniform thickness, and the transfer sheet base material 4 is a thin, uniform, and highly smooth polyester film. (thickness 3~107
) is optimal, and the heat-sensitive transfer layer 5 is composed of a homogeneous coating layer or a matrix layer in which components are uniformly dispersed in a homogeneous coating layer 11. It is preferable that the heat-sensitive transfer layer 5 is thermally melted during heat-sensitive recording and easily transferred/transferred to the heat-sensitive color-receiving layer 6. It is important that the heat-sensitive transfer layer 5 has a sharp melting point and a low melt viscosity. Bisphenol A as a color developer
If it is necessary to use substances with high melting points,
The thermal transfer sensitivity of the thermal transfer 1i5 can be adjusted by dissolving and mixing a known sensitizer or a low melting point substance that does not inhibit thermal color development. Although it is possible to omit the binder for fixing the heat-sensitive transfer layer 5, in applications where it is required, a thermoplastic binder having a transition point of the fortune-telling temperature from the melting point of the heat-sensitive transfer layer 5 may be underlayed on the base material 4. Coating is desirable.

As the dye precursor used in the present invention, leuco dyes such as triphenylmethane type, phenothiazine type, spiropyran type, spiropyran group, indolinospiropyran type, fluoran type, rhodamine lactam type, and leuco auramine type can be used. Bisphenol A as a color developer
Phenolic acidic compounds such as 1-alkylphenol, allylphenol, and novolac type phenol resin, organic acids, organic sulfonic acids, and polyvalent metal salts of organic carboxylic acids can be used.

(Effects of the Invention) In the heat-sensitive recording copying sheet of the present invention, as a result of separately applying a dye precursor, which is a heat-sensitive color forming component, and its color developer to a recording sheet, which is a receiving sheet, and a transfer sheet, a heat-sensitive recording state is obtained. The ability to develop color was essentially prevented, and it became possible to produce a sheet in which the background coloration seen in thermal paper or the coloration caused by hot solvents other than during recording was fundamentally improved.

In addition, as a result of applying the dye precursor to a predetermined area on the recording paper, which is a receiving sheet, the area to be coated with the expensive dye precursor can be reduced to the minimum necessary amount, which contributes to reducing production costs. You can choose the hue. Furthermore, the degree of freedom in form design has been expanded, and it has become possible to make thermal recording paper multifunctional by using it in combination with pressure-sensitive recording and other recording materials.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a thermal transfer recording method using a thermal printer. FIG. 2 is an explanatory diagram of the state of use of the thermal copying sheet of the present invention. FIG. 3 is an explanatory cross-sectional view of the thermal copying sheet of the present invention. 4, 5, and 6 are cross-sectional explanatory diagrams showing the state of thermal recording on the thermal copying sheet of the present invention. ...Recording paper, 4...Transfer sheet base material, 7
... Receiving sheet base material, 5... Thermal transfer layer (developer layer), 6... Thermal color development receiving layer (dye precursor receiving layer).

Claims (1)

[Claims] In a heat-sensitive recording system whose heat-sensitive color forming components include a colorless or light-colored electron-donating dye precursor and an electron-accepting color developer that reacts with the dye precursor to develop color when heated, the smooth surface of the sheet is heat-sensitive. A transfer sheet provided with a heat-sensitive transfer layer containing only a color developer as a color-forming component, and a heat-sensitive color-receiving layer containing only a dye precursor as a heat-sensitive color-forming component are coated on a predetermined portion of the surface where thermal recording is required. A thermal copying sheet made in combination with recording paper.