JP2002011960A - Multi-color recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-color recording medium capable of guaranteeing color developing of a desired tinge at least in one color. SOLUTION: The multi-color recording media (10, 40, 50 and 60) comprise supports (12, 42, 52 and 62), and color developing layers (14, 44, 54 and 64) coating on surfaces of the supports. The each developing layer is formed by uniformly distributing many pressure sensitive microcapsules (18, 48, 58M and 68BK) in the heat sensitive color developing layers (16, 46, 56 and 66), and a color material of a first color is sealed in each microcapsule. Temperature/ pressure characteristics for breaking the microcapsule by a predetermined pressured at a first temperature are given to the microcapsule, and temperature color developing characteristics for color developing a second color at a second temperature at least higher than the first temperature are given to the color developing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-color (multi-color) recording medium configured to emit at least two colors.

[0002]

2. Description of the Related Art As a multi-color recording medium as described above, an add-on type multi-color thermal paper capable of developing two or more colors is already known. For example, when two colors are to be formed by using such a colored heat-sensitive paper, a heat-sensitive coloring layer is formed on a sheet of paper, and when the heat-sensitive coloring layer has a single-layer structure, two types of leuco dyes ( That is, the first
And the developer are uniformly distributed, and the heat-sensitive coloring layer has a multilayer structure (two-layer structure).
, One type of leuco dye and developer are uniformly distributed in each layer. The color developer is appropriately selected so that the color development temperature of the first leuco dye is lower than the color development temperature of the second leuco dye. Sensitizers are added to the layers as appropriate.

As is well known, the leuco dye itself is usually a milky white or translucent powder, and such a leuco dye develops a color by a chemical color-forming reaction with a color developer to exhibit a predetermined color. In order for the leuco dye and the developer to cause a chemical color reaction to produce a sufficient concentration of color, the condition is that both the leuco dye and the developer are in a heat-melted state. .

Accordingly, when the heat melting temperature of the first leuco dye is applied to the thermosensitive coloring layer, the first leuco dye develops a color and exhibits a first color, and the thermosensitive coloring layer heats the second leuco dye. When the melting temperature is applied, both the first and second leuco dyes each develop a color mixture of the first and second colors. In short, by selectively applying a low temperature and a high temperature to the thermosensitive coloring layer, it is possible to obtain a coloring by the first leuco dye and a color mixture by the coloring of the first and second leuco dyes. For example, if the first and second leuco dyes are selected to produce magenta and cyan, respectively, a magenta color is obtained on a low temperature side, and a mixed color of magenta and cyan, that is, a blue color is obtained on a high temperature side. .

Further, in the conventional color-added multicolor thermosensitive recording medium, the color-forming temperature of the low-temperature leuco dye of the first and second leuco dyes (ie, the leuco dye for magenta coloring in the above example). Is set to at least 100 ° C. or higher. This is because there is often a chance that a multicolor heat-sensitive recording medium will be exposed to a temperature of around 100 ° C. on a daily basis. That is, if the color development temperature of the low-temperature leuco dye is set to, for example, 80 ° C., if the multicolor thermal recording medium is inadvertently exposed to a temperature of 80 ° C. or more, erroneous coloration such as background stains may occur there. It is because it is. On the other hand, when the color temperature of the low-temperature leuco dye is set to at least 100 ° C., the color temperature of the high-temperature leuco dye (that is, the leuco dye for cyan coloring in the above example) is determined by the color temperature of the low-temperature leuco dye. (at least
It is necessary to set the temperature sufficiently higher than 100 ° C). If the temperature difference between the color temperature of the low-temperature leuco dye and the color temperature of the high-temperature leuco dye is not sufficiently separated, the color of the high-temperature leuco dye will develop at a low concentration when the low-temperature leuco dye develops. This is because a phenomenon, so-called fog, may occur. As a result, the overall required printing energy for a conventional multi-color thermal recording medium is quite large.

JP-A-08-282115 and JP-A-09-7663
Japanese Patent Application Laid-Open No. 4 (1999) -1999 discloses that, in the above-described additive-type multi-color thermal recording medium, even if the temperature difference between the coloring temperature of the low-temperature leuco dye and the coloring temperature of the high-temperature leuco dye is relatively close, It is disclosed that a high-temperature leuco dye is encapsulated in a heat-sensitive microcapsule in order to prevent the occurrence of the phenomenon. That is, when the heat-sensitive microcapsules are heat-melted at a predetermined temperature (color-forming temperature of the high-temperature leuco dye), the high-temperature leuco dye flows out and performs a color-forming reaction with the color developer, so that the heat-sensitive microcapsules are Until heat melting, color development of high temperature side leuco dye is completely prevented,
The fogging during the color development of the low-temperature leuco dye is prevented.

[0007]

It has been pointed out that, as a problem of the above-described color-added multi-color thermal recording medium, a desired color may not be obtained. For example, various types of magenta colors are known, but the magenta colors are limited to those obtained with leuco dyes, and when considering combinations with leuco dyes of other colors. Therefore, the selection range of the magenta color is further narrowed in consideration of the temperature condition. Some users of multi-color thermal recording media desire to obtain at least one color having a desired tint, but unless the desired tint is obtained only with one type of leuco dye. However, it is not possible to meet such a user request. On the other hand, even if a magenta leuco dye is appropriately mixed to obtain a desired magenta color, a desired heat melting temperature is not always obtained for the mixed leuco dye. Further, in the case of obtaining three or more colors, the range of selection of the leuco dye is further narrowed, and it can be said that it is almost impossible to obtain a desired color for a certain color.

In addition, in the above-described additive-type multi-color thermal recording medium, only one of the basic colors can be independently formed, but the other basic colors are not independently formed. Can not. For example, when magenta and cyan are selected as the basic colors as in the above-described example, if one of the colors, for example, magenta is independently colored, blue due to a mixed color of magenta and cyan is obtained. However, cyan cannot be independently colored. Thus, the conventional additive-type multicolor recording medium is inferior in terms of color-forming efficiency.

Accordingly, an object of the present invention is to provide a multi-color recording medium configured so that at least one of the basic colors can produce a desired tint.

[0010] Still another object of the present invention is to provide a structure in which at least one of the basic colors not only can guarantee the formation of a desired color but also independently obtain the color of another basic color. To provide a multi-color recording medium.

On the other hand, another problem is that the overall required printing energy for the conventional additive-type multi-color thermal recording medium is large. JP-A-08-282115 and JP-A-09-7663
In the color-added multicolor heat-sensitive recording medium disclosed in Japanese Patent Publication No. 4 (1999), even if the color development temperature of the high-temperature leuco dye could be set to a relatively low temperature side, erroneous coloring such as a base stain of the low-temperature leuco dye was performed. In order to prevent this, it is necessary to set the color development temperature to a high temperature of at least 100 ° C. as before.

Therefore, still another object of the present invention is to provide a multi-color recording medium of the type described above, wherein even if the color development temperature of one of the basic colors is set to 100 ° C. or less, the background smudge etc. An object of the present invention is to provide a multi-color recording medium capable of preventing erroneous color formation and effectively preventing fog with other colors.

[0013]

SUMMARY OF THE INVENTION A multicolor recording medium according to the present invention comprises a support and a color forming layer applied to the surface of the support. The color-forming layer is formed by distributing a large number of pressure-sensitive microcapsules in the heat-sensitive color-forming layer, and a color material of the first color is sealed in each pressure-sensitive microcapsule. The pressure-sensitive microcapsules are provided with a temperature / pressure color development characteristic which breaks down at a first temperature and under a predetermined pressure to form a color, while the thermosensitive color layer has at least a first color.
Temperature color developing characteristic that develops the second color at a second temperature higher than the temperature of the second color.

In a preferred embodiment of the present invention, the heat-sensitive coloring layer contains at least one type of leuco dye and a color developing agent, and the leuco dye has a color-forming property of forming a color at a second temperature. Is given. The heat-sensitive color-forming layer may further contain another type of leuco dye, in which case the other type of leuco dye is provided with color-forming properties such that the color is formed at a third temperature higher than the second temperature. .

[0015] In another preferred embodiment of the present invention,
The thermosensitive coloring layer includes a thermosensitive microcapsule enclosing at least one type of leuco dye and a developer for the leuco dye, wherein the thermosensitive microcapsule has a temperature at which the thermosensitive microcapsule is thermally destroyed under a second temperature. Destructive properties are imparted, and the leuco dye is imparted with a thermochromic property that is adapted to develop color at a second temperature. The heat-sensitive coloring layer may further comprise heat-sensitive microcapsules encapsulating another type of leuco dye, in which case the heat-sensitive microcapsules may be broken at a third temperature higher than the second temperature. And the leuco dye is provided with a color-forming property adapted to develop color at a third temperature.

In the multicolor recording medium according to the present invention, a sensitizer for adjusting the color-forming temperature of the leuco dye is added to the heat-sensitive color-forming layer as required, whereby the color-forming temperature is adjusted to the second temperature. You may make it substantially correspond.

In the multicolor recording medium according to the present invention, the temperature characteristics of the temperature / pressure coloring characteristics of the pressure-sensitive microcapsules are preferably obtained from the melting temperature characteristics of the thermosensitive coloring layer. The pressure characteristic of the color development characteristic is obtained from the thickness of the wall film of the pressure-sensitive microcapsule.

In a preferred embodiment of the multicolor recording medium according to the present invention, the first temperature is set to 100 ° C. or lower in order to reduce the overall printing energy.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a multicolor recording medium according to the present invention will be described with reference to the accompanying drawings.

Referring first to FIG. 1, a first embodiment of a multi-color recording medium according to the present invention is indicated generally by the reference numeral 10, wherein the multi-color recording medium 10 comprises a suitable support such as a sheet of paper 12. And a coloring layer 14 applied to one surface of the sheet paper 12. In the first embodiment, the coloring layer 14 is formed as a number of pressure-sensitive microcapsules 18 uniformly distributed in the thermosensitive coloring layer 16.

The thermosensitive coloring layer 16 comprises a first leuco dye component,
In FIG. 1, the first leuco dye component is represented by a symbol “□”, the second leuco dye component is represented by a symbol “、”, and the developer component is composed of a second leuco dye component and a developer component. Is conveniently indicated by the symbol “x”. In the first embodiment, the first leuco dye component “□” is composed of a cyan color leuco dye having a heat melting temperature of about 147 ° C., and such a cyan color leuco dye is, for example, Blue220 manufactured by Yamada Chemical Co., Ltd. Available. The second leuco dye component “○” is composed of a black color leuco dye having a heat melting temperature of about 192 ° C., and such a black color leuco dye is available, for example, as ODB manufactured by Yamamoto Kasei Co., Ltd.
As the developer component "X", K-5 manufactured by Asahi Denka Kogyo Co., Ltd. is used, and the K-5 has a heat melting temperature of about 145 ° C. Although not shown in FIG. 1, acetoacetanilide is appropriately added to the thermosensitive coloring layer 16 as a sensitizer component for controlling the respective coloring temperatures of the leuco dye for cyan coloring and the leuco dye for black coloring. .

The pressure-sensitive microcapsules 18 are filled with, for example, a magenta coloring material, and the magenta coloring material is formed by dissolving or dispersing a magenta dye in an appropriate vehicle. For the vehicle, a suitable transparent oil or a suitable low-melting wax (melting point of 90 ° C or less) which became liquid at room temperature
Can be used. As for the magenta dye, any magenta dye can be appropriately selected. In the present embodiment, the vehicle is RKS (Rutgers Kureha Sol
A transparent oil available as KMC-113 (2,7 diisopropyl naphthalene) from Vents GmbH is used, and as the magenta dye, Rhodamine Lake T (magenta dye) is used. In FIG. 1, the magenta color material enclosed in the pressure-sensitive microcapsule 18 is indicated by “M” representing magenta.

The wall film of the pressure-sensitive microcapsule 18 is formed of a melamine resin colored in the same color (usually white) as the sheet paper 12. Such a pressure-sensitive microcapsule 1
8 is a well-known microcapsule manufacturing method such as Insight (i
n situ) can be produced by a polymerization method or the like,
The average particle size is about 5μm ~ 6μm,
The thickness of the wall film is such that the pressure-sensitive microcapsules 18 can be broken under a pressure of 0.2 MPa or more accompanied by a shearing force.

The pressure-sensitive microcapsules 18 which can be broken under a pressure of 0.2 MPa or more accompanied by a shearing force will be described below.
An example for the production of (average particle size of about 5 μm to about 6 μm) is shown.

1) First, the following three solutions are prepared. (A) Magenta color material solution KMC-113 (2,7 diisopropyl naphthalene) ... 100 g Rhodamine lake T ... 4 g (B) Protective colloid aqueous solution Partial sodium salt of polyvinylbenzene sulfonic acid ... 5 g Purified water ... 95 g (C) Melamine- Formalin prepolymer aqueous solution Melamine ... 11.2 g Formalin ... 28.8 g Purified water ... 40 g (Note that formalin is 37% formaldehyde adjusted to pH 9 with 2% aqueous sodium hydroxide solution. 28.8 g of this formalin and 11.2 g of melamine And heated to 70 ° C., and after the melamine was dissolved, 40 g of purified water was added and stirred to obtain (C) a melamine-formalin prepolymer aqueous solution.)

2) Next, (A) a magenta color material solution and (B) a protective colloid aqueous solution are mixed, and this mixture is stirred with a homogenizer to prepare (D) an emulsified dispersion (O / W emulsion). . At this time, the emulsified dispersion was dispersed by adjusting the rotation speed and the stirring time of the homogenizer so that the magenta colorant solution (A) became droplets having an average particle size of about 4.5 μm.

3) Next, the melamine-formalin prepolymer aqueous solution (C) is added to the above emulsified dispersion and mixed, and the mixture is slowly stirred while maintaining the temperature at 30 ° C.
The mixture is adjusted to pH 3 to pH 6 by appropriately adding an aqueous acetic acid solution. Subsequently, the temperature of the mixed solution is kept at 60 in this state.
C. and the polycondensation reaction was allowed to proceed with stirring for about 1 hour to obtain pressure-sensitive microcapsules 18 having an average particle size of about 5 μm. 4) Finally, titanium oxide fine powder having an average particle size of about 0.1 μm was appropriately added to the pressure-sensitive microcapsule dispersion liquid produced above, and electrically adsorbed on the surface of the microcapsule to whiten the capsule.

The thickness of the wall film of the pressure-sensitive microcapsule 18 thus obtained is such that it can be broken under a pressure of 0.2 MPa or more accompanied by a shearing force. The thickness of the wall film of the pressure-sensitive microcapsule 18 mainly depends on the amount of melamine in the melamine-formalin prepolymer aqueous solution, and the greater the amount, the greater the thickness.

Next, a production example of the sheet of the present invention will be described below. The color forming layer 14 is obtained by applying a composition liquid having the composition shown in the following table to the sheet paper 12 and drying it. Composition parts by weight (1) Aqueous dispersion of 25 W% microcapsules… 1.0 (2) Aqueous dispersion of 17 W% Blue220… 0.2 (3) Aqueous dispersion of 17 W% ODB… 0.2 (4) 20 W% K-5 water Dispersion liquid ... 1.0 (5) Aqueous dispersion liquid of 17W% acetoacetanilide ... 0.5 (6) Aqueous solution of 20W% PVA (degree of polymerization 500) ... 0.5 Here, composition (1) is obtained by mixing 25 microcapsules 18 in purified water.
It is dispersed (suspended) by adding weight percent.
Composition (2) is Blue220 (leuco dye for cyan coloring) in purified water
Was added and dispersed (suspended) by 17% by weight. Blue 220 is a powder having an average particle size of 1 μm or less. composition
(3) is a solution obtained by adding 17% by weight of ODB (leuco dye for black coloring) to purified water and dispersing (suspending) the OD.
B is also a powder having an average particle size of 1 μm or less. Composition (4) is obtained by adding 20% by weight of K-5 (a color developer) to purified water and dispersing (suspending) the same. Composition (5) is obtained by adding 17% by weight of acetoacetanilide (sensitizer) to purified water and dispersing (suspending) the same.
m or less powder. Composition (6) is a solution obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water.

The multicolor recording medium 10 having the coloring layer 14 as shown in FIG. 1 is obtained by applying the above composition liquid on the sheet paper 12 in an amount of about 4 to 6 grams per square meter and drying. be able to. Since such a color forming layer 14 contains acetoacetanilide as a sensitizer, the heat melting temperature of the color developer (K-5) is lowered from about 145 ° C. to about 90 ° C., and the cyan color leuco dye ( B
lue220) is reduced from about 147 ° C to about 120 ° C, and the color developing temperature of black leuco dye (ODB) is about 1 ° C.
Reduced from 92 ° C to about 180 ° C. Of course, the amount of acetoacetanilide to be added is determined so that each leuco dye can obtain a desired color density at a controlled color temperature. The polyvinyl alcohol (PVA) functions as a binder, and has a function of fixing and integrating the compositions (1) to (5) with each other and fixing the coloring layer 14 to the sheet paper 12.

FIG. 2 is a graph showing the coloring characteristics of the coloring layer 14 of the multicolor recording medium 10 configured as described above. As shown in the graph, the magenta coloring region M, the blue coloring region BL, the first black coloring region BK1, and the cyan coloring region C depend on the pressure and the temperature to be applied to the coloring layer 14.
And a second black coloring region BK2. Color development on the color-forming layer 14 of the multi-color recording medium 10 can be performed using a conventional thermal head. By appropriately setting the pressing force of the thermal head on the color-forming layer 14 of the multi-color recording medium, Also, by appropriately setting the heating temperature of each heating element of the thermal head according to the color pixel data, the magenta color dot, the blue color dot, the cyan color dot, and the black color dot for the color development characteristics shown in FIG. Can be selectively obtained.

More specifically, the thermal head applies at least 0.2 MPa to the color forming layer 14 of the multicolor recording medium 10.
When the heating element of the thermal head is heated to a temperature between 90 ° C. and 120 ° C., for example, 100 ° C. while being pressed at the above pressure, for example, 0.3 MPa, the pressure and temperature conditions are included in the magenta coloring area M. It is. Under such a pressure and temperature condition, the developer component “x” is heated and melted due to the eutectic action with the sensitizer (acetoacetanilide). A pressure of 0.3 MPa is applied directly. Thus, the pressure-sensitive microcapsules 18 are broken, and the magenta coloring material is released therefrom, thereby forming magenta coloring dots on the coloring layer 14. In short, the pressure-sensitive microcapsules 18 distributed in the heat-sensitive coloring layer 16 are given a temperature / pressure coloring property that they are broken at a predetermined temperature and under a predetermined pressure to form a color.

When the thermal head is pressed against the coloring layer 14 of the multi-color recording medium 10 with a pressure of at least 0.2 MPa, for example, 0.3 MPa, the heating element of the thermal head is heated to 120 ° C. and 180 ° C. Temperature between eg 150
When heated to ° C., the pressure and temperature conditions are included in the blue coloring region BL. Under such pressure and temperature conditions, the cyan color leuco dye component “□” is hot-melted due to the eutectic action of the developer and the sensitizer (K-5). The dye component “□” develops cyan by a color development reaction with the developer component “x”. At this time, under the pressure and temperature conditions of the blue coloring region BL, magenta coloring by the microcapsules 18 is also obtained. Thus, blue coloring dots formed by mixing cyan and magenta are formed on the coloring layer 14.

Further, when the thermal head is pressed against the color forming layer 14 of the multi-color recording medium 10 at a pressure of at least 0.2 MPa or more, for example, 0.3 MPa, the heating element of the thermal head is heated to a temperature of 180 ° C. or more, for example, 200 ° C. When heated to ° C., the pressure and temperature conditions are included in the first black coloring region BK1. Under such pressure and temperature conditions,
The black coloring leuco dye component “○” is heated and melted due to the eutectic action of the color developer and the sensitizer. Therefore, the black coloring leuco dye component “○” is replaced with the developer component “x”. The black color is formed by the color forming reaction, and black color dots are formed on the color forming layer 14. In addition, under the pressure and temperature conditions of the first black coloring region BK1, the microcapsules 1
No. 8, magenta coloring and cyan coloring by the leuco dye component for cyan coloring are also obtained. However, since these magenta hues and cyan hues are both absorbed by black coloring, neither magenta coloring nor cyan coloring is recognized.

On the other hand, when the thermal head is pressed against the coloring layer 14 of the multi-color recording medium 10 at a pressure of at least 0.2 MPa or less, for example, 0.01 MPa, the heating elements of the thermal head are heated to 120 ° C. and 180 ° C. Temperature between, for example
When heated to 150 ° C., the pressure and temperature conditions are included in the cyan coloring region C. Under such pressure and temperature conditions, the cyan color leuco dye component “□” is hot-melted due to the eutectic action of the developer and the sensitizer, and thus the cyan color leuco dye component “□”. Develops cyan by a coloring reaction with the developer component “x”, and cyan coloring dots are formed on the coloring layer 14. Under the pressure and temperature conditions of the cyan coloring region C, magenta cannot be colored because the microcapsules 18 have strength not to be destroyed.

In a state where the thermal head is pressed against the color forming layer 14 of the multi-color recording medium 10 with a pressure of at least 0.2 MPa or less, for example, 0.01 MPa, the heating element of the thermal head is heated to a temperature of 180 ° C. or more, for example, 200 ° C. When heated to ° C., the pressure and temperature conditions are included in the second black coloring region BK2. Under such pressure and temperature conditions, the black color leuco dye component “○” is hot-melted due to the eutectic action of the color developer and the sensitizer, and thus the black color leuco dye component ““ ”. Is the developer component "x"
The black color is formed in the color-forming layer 14 by forming black by the color-forming reaction with Note that under the pressure and temperature conditions of the second black coloring region BK1, cyan coloring is also obtained by the leuco dye component for cyan coloring, but since this cyan hue is absorbed by black coloring, cyan coloring is not recognized.

Referring to FIG. 3, there is schematically shown a recording apparatus for recording an image on the multi-color recording medium 10 constructed as described above.
It is configured as a printer.

As shown in FIG. 3, the recording apparatus includes a housing 20 having a substantially rectangular shape, and an inlet 22 for introducing the multi-color recording medium 10 is formed on the upper wall of the housing 20. . An outlet 24 for discharging the multi-color recording medium 10 is formed on one of the side walls of the housing 20. FIG. 3 shows a multi-color recording medium 10.
The multi-color recording medium 10 is introduced into the inlet 22 when the image is recorded, is moved along the moving path 26, and is discharged from the outlet 24 during image recording.

A thermal head support 28 is provided at a predetermined position in the housing 20, and a part of the moving path 26 is defined by the thermal head support 28. The thermal head support 28 is first thermal head 30 ₁ and the second thermal head 30 ₂ sequentially toward the discharge port 24 mounted from the inlet 22, the thermal head movement path of multi-color recording medium 10 A large number of electric resistance elements, that is, heating elements are arranged in a straight line extending in the transverse direction and along the extending direction. In this embodiment,
The first thermal head 30 ₁ is used to obtain a magenta color dot and the blue color dot, the second thermal head 30 ₂ is used to obtain a cyan color dots and black color dots. The first and second thermal heads 30 ₁ and 30 ₂ of the respective mutually the same number of heating elements of (n) is included.

Referring to FIG. 4, a first thermal head
30₁A part of the n heating elements included in
A second thermal head, designated R1, R12 and R13
30 ₂A part of the n heating elements included in
1, R22 and R23. It is clear from FIG.
, R heating elements R11, R12, R13,.
n and n heating elements R21, R22, R23,... R2n
Are arranged in a matrix of 2 rows and n columns, and both n
Heating elements (R11, R12, R13,... R1n: R2
1, R22, R23,... R2n) are multicolor
-Are aligned with each other along the direction of movement of the recording medium 10
You.

The n number of heating elements R11 of the first thermal head 30 _1, R12, R13, ... R1n is connected to the first thermal head drive circuit 32 _1, the thermal head drive circuit 32 ₁ of the first, n heating elements R1
1, R12, R13,... R1n are selectively energized in accordance with one line of color pixel data to generate heat. For example, when the color pixel data is magenta pixel data, the corresponding heating element (R11, R12, R
, R1n) is about 100 ° C., and when the color pixel data is blue pixel data, the heating temperature of the corresponding heating element (R11, R12, R13,... R1n) is about 150 ° C. .

The second thermal head 30 ₂ of n heating elements R21, R22, R23, ... R2n are connected to the drive circuit 32 ₂ second thermal head, by the second thermal head drive circuit 32 _2, n heating elements R2
1, R22, R23,... R2n are selectively energized in accordance with one line of color pixel data to generate heat.
For example, when the color pixel data is cyan pixel data, the corresponding heating elements (R21, R22, R23,
.. R2n) is about 150 ° C., and when the color pixel data is black pixel data, the heating temperature of the corresponding heating element (R11, R12, R13,... R1n) is about 200 ° C.

As shown in FIG. 3, the first thermal head 30 ₁ is applied first roller platen 34 _1, pressure applying spring means 36 ₁ first to the first roller platen 34 ₁ Be combined. First pressure applying spring means 36 ₁ is configured to exert, for example, from about 0.3MPa greater than 0.2MPa relative to the first roller platen 34 _1, whereby the first roller platen 34 ₁ Part of about 0.3MPa It is pressed against the first thermal head 30 _2.

[0044] Further, as shown in FIG. 3, the second thermal head 30 ₂ applies the second roller platen 34 _2, this is the second roller platen 34 ₂ second pressure applying spring means 36 ₂ are combined. The second pressure applying spring means 36 ₂ 0 relative to the first roller platen 34 _2.
Is configured to exert less than for example about 0.01MPa to 2 MPa, thereby the second roller platen 34 ₂ about 0.01MP
It is pressed against the second thermal head 30 ₂ a.

When a color image is recorded on the color-forming layer 14 of the multi-color recording medium 10, each of the above-described heating elements has a size and shape corresponding to a pixel unit (ie, dot) of the color image. That is, as will be described later, a dot as a pixel unit is generated on the coloring layer 14 by the heat generated by each heating element. In the present embodiment, the dot size is about 50 μm to 100 μm. It is given to each heating element.

In FIG. 3, reference numeral 37 is the first reference numeral.
And shows a control circuit board for controlling the second thermal head 30 ₁ and 30 ₂ of the first and second driving operation of each of the drive circuit 32 ₂ and 32 _2, also reference numeral 38 indicates a power supply this the power supply device 38, power supply to the first and each of the heating elements and the control circuit board 37 and the like of the second thermal head 30 ₁ and 30 ₂ are carried out.

As described above, at the time of recording a color image, the multicolor recording medium 10 is introduced into the inlet 22. At this time, the orientation of the multicolor recording medium 10 is such that the color forming layer 14 side is the first and second layers. Thermal head 30 ₁
And 30 ₂ of the respective heating elements (R11, ... R1n;
R21,... R2n).

Next, a description will be given of a coloring process when a color image is recorded on the coloring layer 14 of the multi-color recording medium 10 by using the above-described recording apparatus.

[0049] Multi when the color recording medium 10 is passed between the first thermal head 30 ₁ and the first roller platen 34 _1, color layer 14 of the multi-color recording medium 10 first pressure applying spring means 36 first heating element R11 of the thermal head 30 ₁ for _1, R12, R1
3,... R1n receives a pressure accompanied by a shearing force of 0.3 MPa from R1n. When each heating element is not energized, that is, when each heating element is at normal temperature, the pressure 0.3 MPa is applied to the coloring layer 14. Since it exhibits a solid phase, it is not hindered and directly affects the microcapsules 18.

However, when _one of the heating elements R11, R12, R13,... R1n of the first thermal head 301 is energized based on one line of color pixel data, the energized heating element (R11 ,... R1n) are heated to at least about 100 ° C. That is, if the color pixel data is magenta pixel data, the corresponding heating element (R11,..., R1n) is heated to about 100 ° C. If the color pixel data is blue pixel data, the corresponding heating element (R11,. ... R1n) is heated to 150 ° C. In any case, the heating elements (R11,.
When the temperature of at least 100 ° C. is applied to the color forming layer 14 according to 1n), the developer component “x” is thermally melted due to the eutectic action with the sensitizer, and thus the heating elements (R11,.
R1n) penetrates the coloring layer 14 as shown in FIG. 5 and exerts a pressure of about 0.3 MPa on the microcapsules 18. Thus, the microcapsules 18 are broken under a pressure of about 0.3 MPa, and the magenta coloring material is released from the broken microcapsules. Heating element (R11,... R1
When the heating temperature of n) is about 100 ° C., the magenta coloring dot is formed on the coloring layer 14 since the leuco dye component “□” for cyan coloring has not been melted yet. When the heating temperature of the heating elements (R11,... R1n) is about 150 ° C., the leuco dye component “□” for cyan coloring is heat-melted due to the eutectic action of the developer and the sensitizer. A cyan color is formed by a color development reaction with the developer component “x”, and a blue color dot is formed on the color forming layer 14 at this time.

Next, when the multi-color recording medium 10 is passed between the second thermal head 30 ₂ and the second roller platen 34 _2, a multi-color recording medium 10
The second thermal head 30 ₂ of the heating elements R21 for color development layer 14 and the second pressure applying spring means 36 _2, R2
2, R23 ... R2n receives a pressure of 0.01 MPa. Second
Heating elements R21 of the thermal head 30 _2, R22, R
R2n are energized based on one line of color pixel data, the energized heating elements (R21,... R2n) are heated to at least 150 ° C. That is, if the color pixel data is cyan pixel data, the corresponding heating elements (R21,.
If the color pixel data is black pixel data, the corresponding heating elements (R21,... R2
n) is heated to about 200 ° C. In any case,
When a temperature of at least 150 ° C. is applied to the coloring layer 14 by the heating elements (R21,... R2n), the developer component “X”
Is hot-melted due to the eutectic action with the sensitizer,
The corresponding heating elements (R21,... R2n) penetrate into the coloring layer 14 as shown in FIG.
A pressure of MPa can be exerted, but the microcapsules 18 are not destroyed under a pressure of 0.01 MPa, so that magenta does not develop color.

When the heating temperature of the heating elements (R21,... R2n) is about 150.degree. C., the leuco dye component ".quadrature." For cyan coloring is heated and melted due to the eutectic action of the developer and the sensitizer. However, the black color leuco dye component ““ ”is not melted by heat. Thus, only the cyan-coloring leuco dye component “□” reacts with the color developer component “x” to develop cyan, and thus cyan coloring dots are formed in the color-forming layer 14. On the other hand, a heating element (R2
1,... R2n), when the heating temperature is about 200 ° C., the leuco dye component for cyan coloring “□” and the leuco dye component for black coloring “○” are heat-fused together, so that the developer component “× To produce cyan and black, respectively, but the cyan hue is absorbed by black. At this time, black coloring dots are formed in the coloring layer 14.

Thus, if the recording apparatus as shown in FIGS. 3 and 4 is used, a multicolor image composed of magenta, blue, cyan and black dots is recorded on the multicolor recording medium 10. It is possible. The point to note here is that
The hue of the blue color dot and the cyan color dot will be restricted depending on the type of leuco dye that can be used, but the color of the magenta color dot encapsulated in the microcapsule 18 is substantially restricted. That is, a magenta coloring material having an arbitrary color can be used freely without receiving the same. Of course, in the above embodiment, the magenta, cyan, and black color materials were combined, but other color combinations may be used.
In any case, the color of the coloring material to be sealed in the microcapsule 18 can be freely selected without being substantially restricted.

In the first embodiment, magenta, cyan and black are used as basic colors. According to the recording apparatus shown in FIGS. 3 and 4, among these three basic colors, The two basic colors, magenta and cyan, can be independently generated. If the leuco dye for yellow coloring is used instead of the leuco dye for black coloring, in the graph shown in FIG. 2, in the black coloring region BK1, black coloring is obtained as a mixed color of magenta, cyan and yellow, and In the black coloring region BK2, green coloring is obtained by mixing cyan and yellow. That is, five colors can be generated based on the three basic colors.

In the first embodiment described above, two types of leuco dyes are used in the color-forming layer 14. One of the leuco dyes, that is, the leuco dye components "□" and "発" for cyan coloring, is used. It is also possible to use only one of the leuco dye components for black coloring ““ ”.

In the above-described first embodiment, four colors of magenta, blue, cyan, and black are used.
Although the color is used, only the magenta, blue and black colors may be used. In this case, the recording apparatus shown in FIGS. 30 ₂ , second roller platen 34
Omitting the ₂ and the second pressure applying spring means 36 _2, the first thermal head 30 _1, the first roller platen 34 ₁ and the first using only pressure applying spring means 36 ₁ magenta color, blue color, and Black coloring can be performed. Of course, in such a case, the black coloring region BK
1 as (2) by using a black color is obtained, the structure of the driving circuit 32 ₁ thermal head 30 ₁ is changed. That is, when the color pixel data is black pixel data, the corresponding heating elements (R11,.
It is heated to 0 ° C., whereby black coloring dots are formed on the coloring layer 14.

Further, in the first embodiment described above, about 10% (weight percent) of rhodamine lake T (KMC-113 (transparent oil)) is used as a magenta-based coloring material enclosed in the pressure-sensitive microcapsules 18. Magenta dye) is used, but as a magenta coloring material, 1
Different kinds of magenta coloring leuco dyes or plural kinds of magenta coloring leuco dyes may be used. For example, as a magenta leuco dye, Red-3 manufactured by Yamamoto Kasei Co., Ltd. can be used, and a mixture of other leuco dyes based on the Red-3 to obtain a hue having a desired hue. May be used. Such a magenta coloring leuco dye is dissolved in KMC-113 (transparent oil) and encapsulated in the pressure-sensitive microcapsules 18. Red-3 is a powder at room temperature and its heat melting temperature is about 210 ° C,
However, the pressure-sensitive microcapsules 18 have a magenta coloring area M
When destroyed under the pressure temperature condition (0.3 MPa, about 100 ° C.), the magenta coloring leuco dye (Red-3) is already dissolved by the transparent oil, so the magenta coloring leuco dye is Immediately, a color development reaction occurs with the developer component "x" to give a desired hue. As described above, since the leuco dye is generally milky or translucent, when the leuco dye is encapsulated in the pressure-sensitive microcapsules 18, the wall film is colored with the sheet paper 12. It is not necessary to whiten to match.

Referring to FIG. 6, a second embodiment of a multicolor recording medium according to the present invention is indicated generally by the reference numeral 40. As in the case of the first embodiment, the multi-color recording medium 40 also has a suitable support such as a sheet paper 42.
And a coloring layer 44 applied to one surface of the sheet paper 42. The coloring layer 44 is formed as a number of pressure-sensitive microcapsules 48 uniformly distributed in the thermosensitive coloring layer 46.

Also in the second embodiment, the thermosensitive coloring layer 46 is composed of a first leuco dye component, a second leuco dye component and a developer component. In FIG. □ ”, the second leuco dye component is conveniently indicated by the symbol“ △ ”, and the developer component is conveniently indicated by the symbol“ x ”. As in the case of the above-described first embodiment, the first leuco dye component “□” has a heat melting temperature of about 147 ° C.
As a developer component "X", K-5 (heat melting temperature: about 145 ° C.) manufactured by Asahi Denka Kogyo Co., Ltd. is used. In the second embodiment, the second leuco dye component “△” is composed of a magenta-coloring leuco dye. As such a magenta-coloring leuco dye, the aforementioned Yamamoto Kasei Co., Ltd. Red-3 (having a heat melting temperature of about Two
10 ° C) is used. Although not shown in FIG. 1, acetoacetanilide is also appropriately added to the thermosensitive coloring layer 46 as a sensitizer component for controlling the respective coloring temperatures of the leuco dye for cyan coloring and the leuco dye for magenta coloring. .

A black coloring material is sealed in the pressure-sensitive microcapsules 48, and the black coloring material is formed by dissolving a black dye in a suitable vehicle. As a vehicle, a transparent oil such as KMC-113 (2,7 diisopropyl naphthalene) or a low melting point wax (melting point of 90 ° C. or less) is used. As a black dye, ODB (Yamamoto Kasei Co., Ltd.) That is, a black coloring leuco dye having a heat melting temperature of 192 ° C. is used. In short, in this embodiment, the black color material is KMC-113 (transparent oil)
About 4 W% (weight percent) of ODB (black dye) is used. In FIG. 6, the black color material enclosed in the pressure-sensitive microcapsules 48 is indicated by “BK” representing black.

As in the case of the first embodiment, the wall film of the pressure-sensitive microcapsules 48 is formed of melamine resin,
Such a pressure-sensitive microcapsule 48 can also be manufactured by the in situ polymerization method as described above. Also in the second embodiment, the average particle size of the microcapsules 48 is set to about 5 μm to 6 μm, and the thickness of the wall film of the microcapsules 48 is controlled by the pressure-sensitive microcapsules 48 under a pressure of 0.2 MPa or more accompanied by shearing force. It can be destroyed by.

The color forming layer 44 is obtained by applying a composition liquid having the composition shown in the following table to the sheet paper 12 and drying it. Composition parts by weight (1) Aqueous dispersion of 25W% microcapsules… 1.0 (2) Aqueous dispersion of 17W% Blue220… 0.2 (3) Aqueous dispersion of 17W% Red-3… 0.2 (4) 20W% K-5 Aqueous dispersion of 1.0 ... (5) Aqueous dispersion of 17 W% acetoacetanilide ... 0.5 (6) Aqueous solution of 20 W% PVA (polymerization degree 500) ... 0.5 Here, the composition (excluding composition (1) and composition (3)) 2), (4) or
(6) is the same as in the first embodiment, and composition (1) is obtained by adding 25% by weight of pressure-sensitive microcapsules 48 to purified water and dispersing (suspending) the composition (3). Is a dispersion in which 17% by weight of Red-3 (leuco dye for magenta coloring) is added to purified water and dispersed (suspended), and Red-3 itself is a powder having an average particle diameter of 1 μm or less.

The multicolor recording medium 10 having the coloring layer 44 as shown in FIG. 6 is obtained by applying the above composition liquid on the sheet paper 42 in an amount of about 4 to 6 grams per square meter and drying it. be able to. Since such a color forming layer 44 contains acetoacetanilide as a sensitizer, the heat melting temperature of the color developer (K-5) is reduced from about 145 ° C. to about 90 ° C., and the cyan color leuco dye ( B
lue 220) is reduced from about 147 ° C. to about 120 ° C., and the color developing temperature of the magenta leuco dye (Red-3) is reduced from about 210 ° C. to about 180 ° C.

FIG. 7 is a graph showing the coloring characteristics of the coloring layer 44 of the multi-color recording medium 40 configured as described above. As shown in the graph, depending on the pressure and temperature to be applied to the coloring layer 44, the coloring layer 44
Defines a black coloring region BK, a cyan coloring region C, and a blue coloring region BL. As in the case of the first embodiment, a color image can be recorded on the multi-color recording medium 40 by using a recording apparatus as shown in FIGS.

[0065] More specifically, the multi-color recording medium 40 is first thermal head 30 ₁ and the first roller platen 3
4 ₁ When forced through between the multicolor recording color-forming layer 14 is first heat generating element R11 of the thermal head 30 ₁ for the first pressure applying spring means 36 ₁ of the medium 10,
From R12, R13, ..., R1n, pressure with shear force of 0.3MPa
However, when each heating element is not energized, that is, when each heating element is at room temperature, the pressure of 0.3 MPa is blocked because the color-forming layer 14 is in a solid phase, and the pressure is 0.3 MPa. It does not directly affect the capsule 48.

However, when _one of the heating elements R11, R12, R13,... R1n of the first thermal head 301 is energized based on one line of black pixel data, the energized heating element (R11 ,... R1n) are heated to about 100 ° C.
1,... R1n) gives a temperature of about 100 ° C. to the color-forming layer 44, so that the developer component “x” is hot-melted due to the eutectic action with the sensitizer (acetoacetanilide). Therefore, the heating elements (R11,..., R1n) enter the coloring layer 44 in a manner similar to that shown in FIG. 5, and exert a pressure of about 0.3 MPa on the pressure-sensitive microcapsules 48. Thus, the pressure-sensitive microcapsules 48 are broken under a pressure of about 0.3 MPa to release the black coloring leuco dye, and the black coloring leuco dye is now dissolved in the transparent oil. For this reason, the color develops with the color developer component “x” to give a black color, whereby black color dots are formed on the color forming layer 44. In short, the pressure-sensitive microcapsules 48 distributed in the heat-sensitive coloring layer 46 are given a temperature / pressure coloring property that they are broken at a predetermined temperature and under a predetermined pressure to form a color.

Next, when the multi-color recording medium 40 is passed between the second thermal head 30 ₂ and the second roller platen 34 _2, a multi-color recording medium 40
The second thermal head 30 ₂ of the heating elements R21 for color development layer 44 second pressure applying spring means 36 _2, R2
2, a pressure of about 0.01 MPa is received from R23,. The second thermal head 30 ₂ of the heating elements R21, R2
When any of 2, R23,... R2n is energized based on one line of color pixel data, the energized heating elements (R21,... R2n) are heated to at least 150 ° C. That is, if the color pixel data is cyan pixel data, the corresponding heating element (R21,... R2n)
Is heated to about 150 ° C., and if the color pixel data is magenta pixel data, the corresponding heating element (R21,
... R2n) is heated to about 200 ° C. In any case, the coloring layer 44 is formed by the heating elements (R21,... R2n).
At a temperature of at least 150 ° C., and the developer component “x” is hot melted due to the eutectic action with the sensitizer. Accordingly, the corresponding heating elements (R21,... R2n) are shown in FIG.
Will enter the coloring layer 44 in the same manner as shown in FIG. 4 and exert a pressure of about 0.01 MPa on the pressure-sensitive microcapsules 48, but the pressure-sensitive microcapsules 48 will be destroyed under a pressure of 0.01 MPa. No black color is obtained.

When the heating temperature of the heating elements (R21,... R2n) is about 150 ° C., the leuco dye component “□” for cyan color development is a eutectic effect between the sensitizer and the developer (K-5). However, since the leuco dye component for magenta coloring “△” is not melted by heat, only the leuco dye component for cyan coloring “□” reacts with the color developer component “x” to form cyan. A color is formed, and cyan color dots are formed on the color forming layer 44. On the other hand, heating elements (R21,.
When the heating temperature of 2n) is about 200 ° C., both the leuco dye component for cyan coloring “□” and the leuco dye component for magenta coloring “△” are due to the eutectic action of the sensitizer and the developer. As a result, the two leuco dye components react with the color developer component "x" to form cyan and magenta, respectively, whereby the color forming layer 44 has a blue color composed of a mixture of cyan and magenta. Dots are formed.

In the second embodiment, no other color is mixed at the time of forming black coloring dots on the coloring layer 44 of the multi-color recording medium 40, whereas in the first embodiment, Both the magenta and cyan or cyan colors are mixed in the black coloring dots. As described above, black absorbs its hue even if other colors are mixed therein, but the color itself of black can be slightly influenced to give a dull black color.
However, in the second embodiment, since other colors (cyan and magenta) are not mixed into the black color dots at all, the black color dots exhibit pure black without dullness. Accordingly, the multi-color recording medium 40 of the second embodiment is particularly excellent as a business document recording medium that causes characters and the like to be colored in black and graphs and the like to be colored in colors other than black.

Referring to FIG. 8, a third embodiment of a multicolor recording medium according to the present invention is indicated generally by the reference numeral 50. As in the case of the first and second embodiments described above, the multicolor recording medium 50 also includes a suitable support such as a sheet of paper 52 and a coloring layer 54 applied to one surface of the sheet of paper 52. . In the third embodiment, the color-forming layer 54 is formed by uniformly distributing the pressure-sensitive microcapsules 58M in the heat-sensitive color-forming layer 56 composed of two types of heat-sensitive microcapsules 58C and 58BK and a developer component. It is formed. In FIG. 8, the developer component in the pressure-sensitive coloring layer 56 is indicated by a symbol “x” for convenience, and is not shown in FIG. Acetoacetanilide is also appropriately added as a sensitizer component.

The pressure-sensitive microcapsules 58M are substantially the same as the pressure-sensitive microcapsules 18 used in the first embodiment. That is, a magenta color material is encapsulated in the pressure-sensitive microcapsules 58M, and the magenta color material is formed by dissolving or dispersing a magenta dye in an appropriate vehicle. For example, the magenta color material described above is used. KM
About 4 W% (weight percent) of Rhodamine Lake T (magenta dye) dissolved in C-113 (clear oil) is used. The wall film of the pressure-sensitive microcapsules 58M is formed of a melamine resin colored in the same color as the sheet paper 52 (usually white).
The thickness of the wall film is about 5 μm to 6 μm.
It can be broken under the above pressure. In FIG. 8, the magenta coloring material enclosed in the pressure-sensitive microcapsules 58M is indicated by "M" representing magenta.

The above-mentioned leuco dye for cyan coloring (Blue 220) manufactured by Yamada Chemical Co., Ltd. is encapsulated in a powder in the heat-sensitive microcapsules 58C. Resin material such as polyurethane, polyurea, polyamide or a suitable wax material such as olefin wax.
It is said. In short, the thermosensitive microcapsules 58C are provided with a temperature coloring property that is thermally broken at a temperature of about 120 ° C. or more, for example, about 150 ° C., and develops a color regardless of the pressure applied thereto. In FIG. 8, the leuco dye for cyan coloring enclosed in the thermosensitive microcapsules 58C is indicated by “C” representing cyan.

The heat sensitive microcapsules 58BK are filled with the above-mentioned black color leuco dye (ODB) manufactured by Yamamoto Kasei Co., Ltd. in a powder form. It is formed of a suitable resin such as polyamide or polyurea, and its thermal breakdown temperature is, for example, about 180 ° C. In short, the heat-sensitive microcapsules 58BK are provided with a color development temperature characteristic that is thermally broken at a temperature of about 180 ° C. or more, for example, about 200 ° C., regardless of the pressure applied thereto, and develops a color. In FIG. 8, the leuco dye for black color encapsulation in the thermosensitive microcapsules 58BK is indicated by "BK" representing black.

Both the heat-sensitive microcapsules 58C and the heat-sensitive microcapsules 58BK can be manufactured by a well-known microcapsule manufacturing method, such as an interfacial polymerization method, a phase separation method, or an air suspension method. Is about 3 μm. The thickness of the wall film of the microcapsules 58C is assumed to be able to withstand a pressure exceeding 0.3 MPa at a thermal breakdown temperature of less than 120 ° C, and the thickness of the wall film of the microcapsules 58BK is 180 ° C. If it is less than 0.3 MPa, it can withstand a pressure exceeding 0.3 MPa.

The color forming layer 54 is obtained by applying a composition liquid having the composition shown in the following table to the sheet paper 52 and drying it. Composition parts by weight (1) Aqueous dispersion of 25 W% microcapsules (58M) ... 0.3 (2) Aqueous dispersion of 25 W% microcapsules (58C) ... 0.3 (3) Aqueous dispersion of 25 W% microcapsules (58BK) ... 0.3 (4) 20W% K-5 aqueous dispersion ... 1.0 (5) 17W% acetoacetanilide aqueous dispersion ... 0.5 (6) 20W% PVA (polymerization degree 500) aqueous solution ... 0.5 Here, composition (1) Is obtained by adding and dispersing (suspending) microcapsules 58M in purified water by adding 25% by weight in the same manner as in the first embodiment. Composition (2)
Is a dispersion obtained by adding 25% by weight of microcapsules 58C to purified water. Composition (3) is
It is obtained by adding 25% by weight of microcapsules 58BK to purified water and dispersing (suspending) them. The composition (4) is obtained by adding 20% by weight of K-5 (a color developer) to purified water and dispersing (suspending) the same as in the case of the first embodiment. The composition (5) is obtained by adding acetoacetanilide (sensitizer) to purified water in the same manner as in the first embodiment described above.
It is dispersed (suspended) by adding weight percent.
The composition (6) is obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water and dissolving the same as in the case of the first embodiment.

The multicolor recording medium 50 having the coloring layer 54 as shown in FIG. 8 is obtained by applying the above composition liquid on the sheet paper 52 in an amount of about 4 to 6 grams per square meter and drying. be able to. Since such a coloring layer 54 contains acetoacetanilide as a sensitizer, the heat melting temperature of the color developer (K-5) is reduced from about 145 ° C. to about 90 ° C., and the heat-sensitive microcapsules 58C
The heat melting temperature (coloring temperature) of the cyan leuco dye (Blue220) is lowered from about 147 ° C to about 120 ° C, and the black leuco dye of the thermosensitive microcapsules 58BK
(ODB) has a thermal melting temperature (coloring temperature) of about 192 ° C to about 180 ° C
To be lowered.

The color forming characteristics of the color forming layer 54 of the multi-color recording medium 50 configured as described above are substantially the same as those shown in FIG. A color image can be recorded using a recording device as shown in FIG.

[0078] More specifically, the multi-color recording medium 50 is first thermal head 30 ₁ and the first roller platen 3
4 ₁ When forced through between the first heating element R11 of the thermal head 30 ₁ for color development layer 54 is a first pressure applying spring means 36 ₁ of the multi-color recording medium 50,
From R12, R13, ..., R1n, pressure of about 0.3M with shear force
However, when each heating element is not energized, that is, when each heating element is at room temperature, the pressure is blocked because the color forming layer 54 is in a solid phase and is pressure sensitive. It does not directly affect the microcapsules 58M.

However, when _one of the heating elements R11, R12, R13,... R1n of the first thermal head 301 is energized based on one line of color pixel data, the energized heating element (R11 ,... R1n) are heated to at least about 100 ° C. That is, if the color pixel data is magenta pixel data, the corresponding heating element (R11,..., R1n) is heated to about 100 ° C. If the color pixel data is blue pixel data, the corresponding heating element is about 150 ° C. Heated to ° C. In any case, when a temperature of at least 100 ° C. is applied to the color forming layer 54 by the heating elements (R11,... R1n), the developer component “X” becomes eutectic with the sensitizer (acetoacetanilide). And the heating element (R1
1,... R1n) enter the coloring layer 54 and exert a pressure of about 0.3 MPa on the pressure-sensitive microcapsules 58M.
Thus, the pressure-sensitive microcapsules 58M are broken under a pressure of about 0.3 MPa, from which the magenta coloring material is released. In short, the pressure-sensitive microcapsules 58M distributed in the heat-sensitive coloring layer 56 are given a temperature / pressure coloring property that they are broken at a predetermined temperature and under a predetermined pressure to form a color.

When the heating temperature of the heating elements (R11,... R1n) is about 100 ° C., the heat-sensitive microcapsules 58C,
In this case, magenta coloring dots are formed on the coloring layer 54 because 58BK has not yet been thermally destroyed. On the other hand, the heating temperature of the heating elements (R11,... R1n) is 150 ° C.
In this case, the heat-sensitive microcapsules 58C are destroyed by heat, and the leuco dye for cyan color formation contains a sensitizer and a developer.
In this case, the cyanide-forming leuco dye reacts with the developer component “x” to form cyan, since it is heated and melted due to the eutectic action with (K-5). In the layer 54, blue coloring dots are formed in the coloring layer 14 for mixing colors of magenta and cyan.

Next, the multi-color recording medium 50 is
Thermal head 30₂And the second roller platen 34₂When
Between the multi-color recording media 50
Of the second pressure applying spring means 36₂for
The second thermal head 30 ₂Heating elements R21, R2
2, R23,... Receive a pressure of about 0.01 MPa from R2n.
Second thermal head 30₂Heating elements R21, R2
2, R23, ..., R2n is one line color
When energized based on pixel data, the energized
The heating elements (R21, ... R2n) are heated to at least 150 ° C.
Heated. That is, color pixel data is converted to cyan pixel data.
, The corresponding heating element (R21,... R2n)
Is heated to about 150 ° C and color pixel data is
In the case of the pixel data, the corresponding heating element (R21,
... R2n) is heated to about 200 ° C. In any case
However, the coloring layer 54 is formed by the heating elements (R21,... R2n).
At a temperature of at least 150 ° C,
The agent component “X” is hot-melted for eutectic action with the sensitizer.
, The corresponding heating elements (R21,... R2n) are colored.
After penetrating the layer 54, the pressure-sensitive microcapsules 58M have about 0.
01MPa pressure can be exerted, but pressure sensitive
Microcapsule 58M breaks under pressure of about 0.01MPa
Magenta is not developed.

When the heating temperature of the heating elements (R21,... R2n) is about 150 ° C., the heat-sensitive microcapsules 58C are destroyed by heat, and the leuco dye for cyan coloring develops a eutectic action between the sensitizer and the developer. However, since the heat-sensitive microcapsules 58BK are not thermally destroyed yet, only the leuco dye for cyan coloring reacts with the developer component “x” to form cyan, thereby forming cyan. In the layer 54, cyan coloring dots are formed. On the other hand, a heating element (R2
When the heating temperature of 1,... R2n) is about 200 ° C., both the microcapsules 58C and 58BK are thermally destroyed, and both the cyan and black leuco dyes are thermally fused together. For this reason, a color development reaction occurs with the color developer component “x” to produce cyan and black, respectively. However, since the cyan hue is absorbed by black, black coloring dots are formed in the coloring layer 54 in this case.

Thus, as in the case of the above-described first embodiment, it is possible to record a multicolor image composed of magenta coloring dots, blue coloring dots, cyan coloring dots and black coloring dots on the multicolor recording medium 50. It is possible.

In the third embodiment, the microcapsules 58C in which two types of leuco dyes are encapsulated in the color forming layer 54
And 38BK are used, but it is also possible to use only one of the microcapsules.

As in the case of the above-described first embodiment, also in the third embodiment, a magenta color, a blue color,
Although four colors of cyan and black are used, only magenta, blue and black may be used. In this case, a recording apparatus as shown in FIGS. 3 and 4 is used. from omitted second thermal head 30 _2, the second roller platen 34 ₂ and the second pressure applying spring means 36 _2, the first thermal head 3
0 _1, a first roller platen 34 ₁ and the first pressure applying spring means 36 ₁ only magenta color with, it is possible to perform a blue color and black color.

Further, as in the case of the first embodiment described above, in the third embodiment, about 4 W% of KMC-113 (transparent oil) is used as a magenta-based coloring material enclosed in the microcapsules 58M. (Weight percent) rhodamine lake T
(Magenta dye) is used, but one type of magenta coloring leuco dye or a plurality of types of magenta coloring leuco dye may be used as the magenta coloring material.

Referring to FIG. 9, a fourth embodiment of a multicolor recording medium according to the present invention is indicated generally by the reference numeral 60. As in the first to third embodiments described above, the multicolor recording medium 60 also includes a suitable support, for example, a sheet paper 62, and a coloring layer 64 applied to one surface of the sheet paper 62. . In the fourth embodiment, the coloring layer 64 is composed of two types of heat-sensitive microcapsules 6.
A large number of pressure-sensitive microcapsules 68BK are formed in the heat-sensitive coloring layer 66 composed of 8C, the heat-sensitive microcapsules 68M, and the color developer component. In FIG. 9 as well, the developer component in the developer layer 66 is indicated by a symbol “x” for convenience.

The pressure-sensitive microcapsules 68BK are substantially the same as the pressure-sensitive microcapsules 48 used in the second embodiment. That is, the pressure-sensitive microcapsules 68B
A black coloring material is enclosed in K, and the black coloring material is formed by dissolving a black dye in a suitable vehicle. As in the case of the above-described second embodiment, for example, KMC-113 (transparent oil) or a low-melting wax (melting point of 90 ° C. or less) is used as a vehicle, and the black dye is Yamamoto Kasei as described above. ODB (ie hot melt temperature)
192 ° C black leuco dye). In short, in this embodiment, about 4 W% (weight percent) is added to the above-mentioned KMC-113 (transparent oil) as a black color material.
A solution of ODB is used. Note that, in FIG. 9, the leuco dye for black coloring enclosed in the pressure-sensitive microcapsules 68BK is “BK” representing black.
Indicated by

As in the case of the second embodiment, the wall film of the pressure-sensitive microcapsules 68BK is formed from a melamine resin, and such pressure-sensitive microcapsules 68BK are also formed by the in situ polymerization method described above. It is possible to manufacture. Also in the fourth embodiment, the average particle size of the pressure-sensitive microcapsules 68BK is about 5 μm to about 6 μm, and the thickness of the wall film is about 0.2 MPa or more with the shear force of the pressure-sensitive microcapsules 68BK. That can be broken under pressure.

The heat-sensitive microcapsules 68C correspond to the third
This is substantially the same as the microcapsule 68C used in the embodiment. That is, the heat-sensitive microcapsules 68
C. The leuco dye for cyan coloring manufactured by Yamada Chemical Co.
(Blue220) is encapsulated in a powder, and the wall film is formed of a suitable resin material or a suitable wax material in order to provide the heat-sensitive microcapsules 68C with heat-sensitive destruction characteristics.
The thermal breakdown temperature is, for example, about 120 ° C. Accordingly, the thermosensitive microcapsules 68C are provided with a temperature coloring characteristic which is thermally destroyed at a temperature of about 120 ° C. or more, for example, 150 ° C. and develops color regardless of the pressure applied thereto. In FIG. 9, the leuco dye for cyan color encapsulated in the thermosensitive microcapsules 68C is indicated by “C” representing cyan.

The heat-sensitive microcapsules 68M are encapsulated in powder with the above-described magenta color forming leuco dye (Red-3) manufactured by Yamamoto Kasei Co., Ltd. Is formed of a suitable resin material, for example, a resin such as polyurea or polyamide, and has a thermal breakdown temperature of, for example, about 180 ° C. Accordingly, the thermosensitive microcapsules 68M are provided with a temperature coloring property that is thermally destroyed at a temperature of about 180 ° C. or more, for example, about 200 ° C., and develops a color regardless of the pressure applied thereto. In FIG. 9, the magenta coloring leuco dye encapsulated in the heat-sensitive microcapsules 68M is indicated by "M" representing magenta.

Both the heat-sensitive microcapsules 68C and the heat-sensitive microcapsules 68M are manufactured by a well-known microcapsule manufacturing method as described above, that is, an interfacial polymerization method, an in situ polymerization method, a phase separation method, an air suspension method, or the like. The average particle diameter is about 3 μm, as in the case of the third embodiment. The thickness of the wall film of the heat-sensitive microcapsule 68C is assumed to be able to withstand a pressure exceeding 0.3 MPa at a temperature below about 120 ° C. If the temperature is lower than about 180 ° C., it can withstand a pressure exceeding 0.3 MPa.

The color forming layer 64 is obtained by applying a composition liquid having the composition shown in the following table to the sheet paper 62 and drying it. Composition Weight part (1) 25 W% microcapsule aqueous dispersion (68BK) ... 0.3 (2) 25 W% microcapsule aqueous dispersion (68C) ... 0.3 (3) 25 W% microcapsule aqueous dispersion (68M) ... 0.3 (4) 20W% K-5 aqueous dispersion ... 1.0 (5) 17W% acetoacetanilide aqueous dispersion ... 0.5 (6) 20W% PVA (polymerization degree 500) aqueous solution ... 0.5 Here, composition (1) Is a microcapsule 68B in purified water
K is added (25% by weight) and dispersed (suspended). Composition (2) is obtained by adding microcapsules 68C to purified water.
5 weight percent added and dispersed (suspended). Composition (3) consists of 25 microcapsules in purified water.
It is dispersed (suspended) by adding weight percent.
Composition (4) is obtained by adding 20% by weight of K-5 (developing agent) to purified water and dispersing (suspending). Composition (5) is
17% by weight of acetoacetanilide (sensitizer) was added to purified water and dispersed (suspended). Composition (6)
Is a solution obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water.

The multicolor recording medium 60 having the coloring layer 64 as shown in FIG. 9 is obtained by applying the above composition liquid on the sheet paper 62 in an amount of about 4 to 6 grams per square meter and drying. be able to. Since such a color forming layer 64 contains acetoacetanilide as a sensitizer, the heat melting temperature of the color developer (K-5) is lowered from about 145 ° C. to about 90 ° C., and the cyan color leuco dye ( Blu
e220) has a heat melting temperature (coloring temperature) of about 147 ° C to about 120 ° C
Leuco dye for magenta coloring (Red-3)
Is reduced from about 210 ° C. to about 180 ° C.

The coloring characteristics of the coloring layer 64 of the multicolor recording medium 60 configured as described above are substantially the same as those shown in FIG. A color image can be recorded using a recording device as shown in FIG.

[0096] More specifically, multi-color recording medium 60 is first thermal head 30 ₁ and the first roller platen 3
4 ₁ When forced through between the color development layer 64 is first heat generating element R11 of the thermal head 30 ₁ for the first pressure applying spring means 36 ₁ of the multi-color recording medium 60,
From R12, R13, ..., R1n, pressure of about 0.3M with shear force
However, when each heating element is not energized, that is, when each heating element is at room temperature, the pressure is blocked because the coloring layer 64 exhibits a solid phase, and the pressure is reduced. It does not directly affect the microcapsules 68.

However, when _one of the heating elements R11, R12, R13,... R1n of the first thermal head 301 is energized based on one line of black pixel data, the energized heating element (R11 ,... R1n) are heated to about 100 ° C.
1,... R1n) exerts a temperature of about 100 ° C. on the color forming layer 64, so that the developer component “X” is hot-melted due to the eutectic action with the sensitizer (acetoacetanilide), For this reason, the heating elements (R11,... R1n)
4 into the pressure-sensitive microcapsules 68BK, about 0.3M
Pa pressure can be exerted. Thus, the pressure-sensitive microcapsules 68BK are destroyed under a pressure of about 0.3 MPa, and the leuco dye for black coloring is released. At this time, the leuco dye for black coloring is in a state of being dissolved in the transparent oil. The black color is formed by the color development reaction with the color developer component “x”, thereby forming black color dots on the color formation layer 54. In short, the pressure-sensitive microcapsules 68 distributed in the thermosensitive coloring layer 66
The BK is given a temperature / pressure color developing characteristic of being broken at a predetermined temperature and under a predetermined pressure to form a color.

Next, when the multi-color recording medium 60 is passed between the second thermal head 30 ₂ and the second roller platen 34 _2, a multi-color recording medium 60
The second thermal head 30 ₂ of the heating elements R21 for color development layer 64 second pressure applying spring means 36 _2, R2
2, a pressure of about 0.01 MPa is applied from R23,.
The second thermal head 30 ₂ of the heating elements R21, R2
When any of 2, R23,... R2n is energized based on one line of color pixel data, the energized heating elements (R21,... R2n) are heated to at least 150 ° C. That is, if the color pixel data is cyan pixel data, the corresponding heating element (R21,... R2n)
Is heated to about 150 ° C., and if the color pixel data is magenta pixel data, the corresponding heating element (R21,
... R2n) is heated to about 200 ° C. In any case, the coloring layer 64 is formed by the heating elements (R21,... R2n).
Is subjected to a temperature of at least 150 ° C., so that the developer component “X” is heat-melted due to the eutectic action with the sensitizer, so that the corresponding heating elements (R21,. Black would be able to penetrate layer 64 and exert a pressure of about 0.01 MPa on pressure sensitive microcapsules 68BK, but since pressure sensitive microcapsules 68BK would not be destroyed under a pressure of about 0.01 MPa. Does not develop color.

When the heating temperature of the heating elements (R21,... R2n) is about 150 ° C., the heat-sensitive microcapsules 68C are destroyed by heat, and the leuco dye for cyan color formation is a eutectic of a sensitizer and a developer. Heat-melted for action,
Since the heat-sensitive microcapsules 68M have not yet been subjected to thermal destruction, at this time, only the cyan-coloring leuco dye reacts with the developer component “x” to produce cyan, and thus the cyan coloring dot is formed in the coloring layer 64. Is formed. On the other hand, when the heating temperature of the heating elements (R21,... R2n) is about 200 ° C., both the heat-sensitive microcapsules 68C and 68M are destroyed by heat, and both the cyan-colored leuco dye and magenta-colored. Both the leuco dyes are hot-melted due to the eutectic action of the sensitizer and the developer, and at this time, both leuco dyes react with the developer component “x” to form cyan and cyan, respectively. Magenta is colored, whereby blue coloring dots composed of a mixture of cyan and magenta are formed on the coloring layer 64.

As in the case of the above-described second embodiment, in the fourth embodiment, when a black coloring dot is formed on the coloring layer 64 of the multicolor recording medium 60, other colors are completely mixed. There is no. Therefore, for the same reason as in the second embodiment, the multi-color recording medium 60 according to the fourth embodiment also causes a character to be colored in black and a business document such as a graph to be colored in a color other than black. This is particularly excellent as a recording medium.

In the third and fourth embodiments, the heat-sensitive microcapsules (58C, 58BK; 68C, 68
In order to give M) a thermosensitive coloring property, the wall film is formed of a suitable resin or wax having a predetermined heat-destruction temperature. It should be understood that any type can be used.

In the third and fourth embodiments, the heat-sensitive microcapsules (58C, 58BK;
C, 68M) encapsulates a powdered leuco dye. Such a leuco dye may be added to a suitable vehicle such as KMC-
What dissolved in 113 (transparent oil), low melting point wax, etc. may be enclosed in a thermosensitive microcapsule. In addition, heat-sensitive microcapsules (58C, 58BK; 68C, 68
When a powdered leuco dye is encapsulated in M), the color reaction of the leuco dye does not occur until the wall film is destroyed by heat melting, but the leuco dye dissolved in the liquid is not covered by the heat-sensitive microcapsules. When the wall film softens, a coloring reaction occurs.

[0103]

As is apparent from the above description, according to the multicolor recording medium of the present invention, at least one of the colors can be used in any color without being restricted by temperature conditions and the like. Thus, it is possible to realize a combination of shades that could not be obtained with the conventional additive-type multi-color thermal paper. Further, in the present invention, when a plurality of basic colors are used, two of the basic colors can be independently colored, and in particular, three colors other than black are used as the basic colors. In this case, five colors can be developed.
The multicolor recording medium according to the present invention is superior in terms of color development efficiency as compared with the conventional color-added multicolor thermal paper.

Further, in the multicolor recording medium according to the present invention, the color development temperature of one of the basic colors is 100 ° C.
Even if it is set below, erroneous coloring such as background stain due to temperature can be prevented, which can contribute to a reduction in the overall required printing energy, and also effectively prevents fogging with other colors and provides high quality. An image is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view schematically showing a part of a first embodiment of a multicolor recording medium according to the present invention.

FIG. 2 is a graph showing the coloring characteristics of a coloring layer of the multicolor recording medium shown in FIG.

FIG. 3 is a schematic cross-sectional view showing an example of an image recording apparatus for recording a color image on the multi-color recording medium shown in FIG.

FIG. 4 is a control block diagram of first and second thermal heads included in the image recording device of FIG. 3;

5 is a schematic cross-sectional view schematically showing a state in which a heating element of a thermal head of the recording apparatus shown in FIG. 3 causes a coloring layer of the multi-color recording medium of FIG.

FIG. 6 is a schematic sectional view schematically showing a part of a second embodiment of the multicolor recording medium according to the present invention.

FIG. 7 is a graph showing the coloring characteristics of a coloring layer of the multicolor recording medium shown in FIG.

FIG. 8 is a schematic sectional view schematically showing a part of a third embodiment of the multicolor recording medium according to the present invention.

FIG. 9 is a schematic sectional view schematically showing a part of a fourth embodiment of the multicolor recording medium according to the present invention.

[Explanation of symbols]

10.40.50.60 Multi-color recording medium 12.42.52.62 Support (sheet paper) 14.44.54.64 Coloring layer 18.48.58M.68BK Pressure-sensitive microcapsules 58C.58BK.68C. 68M heat sensitive microcapsule

Claims (8)

[Claims] 1. A multi-color recording medium comprising a support and a color-forming layer coated on the surface of the support, wherein the color-forming layer has a number of pressure-sensitive microcapsules uniformly distributed in the heat-sensitive color-forming layer. Each of the pressure-sensitive microcapsules is filled with a coloring material of a first color, and the pressure-sensitive microcapsules are broken at a first temperature and under a predetermined pressure so as to form a color. Temperature / pressure coloring characteristics, and the heat-sensitive coloring layer is provided with a temperature coloring characteristics capable of developing a second color at least at a second temperature higher than the first temperature. A multi-color recording medium characterized by the above-mentioned. 2. The multicolor recording medium according to claim 1, wherein the thermosensitive coloring layer contains at least one type of leuco dye and a color developing agent thereof, and the leuco dye is the second type of leuco dye.
A multicolor recording medium having a temperature coloring property of coloring at a temperature of 3. The multi-color recording medium according to claim 1, wherein the thermosensitive coloring layer includes a thermosensitive microcapsule encapsulating at least one type of leuco dye, and a developer for the leuco dye. A multicolor recording medium, wherein the capsule has a temperature-destructive property of being thermally destructed at the second temperature, and the leuco dye has a temperature-coloring property of being colored at the second temperature. 4. The multicolor recording medium according to claim 2, wherein the thermosensitive coloring layer contains a sensitizer for adjusting a coloring temperature of the leuco dye, whereby the coloring temperature is adjusted to the second color temperature. A multi-color recording medium substantially matched to the temperature of 5. The multi-color recording medium according to claim 2, wherein said thermosensitive coloring layer further comprises another kind of leuco dye, said another kind of leuco dye being higher than said second temperature. A multi-color recording medium having a temperature coloring property such that a color is formed at a predetermined temperature. 6. The multi-color recording medium according to claim 3, wherein said thermosensitive coloring layer includes thermosensitive microcapsules further enclosing another type of leuco dye, wherein said thermosensitive microcapsules are at a temperature of said second temperature. A multicolor recording medium having a temperature destruction property of being destroyed at a third temperature higher than that of the third color, and having a temperature coloring property of causing the leuco dye to develop color at the third temperature. 7. The multi-color recording medium according to claim 1, wherein a temperature characteristic of a temperature / pressure coloring characteristic of the pressure-sensitive microcapsule is obtained from the thermosensitive coloring layer. A multicolor recording medium, wherein a pressure characteristic of the temperature / pressure coloring characteristic is obtained from a thickness of a wall film of the pressure-sensitive microcapsule. 8. The multi-color recording medium according to claim 1, wherein the first temperature is less than the first temperature.
A multi-color recording medium set at a temperature of 100 ° C. or lower.