JP2002019298A - Multi-color recording medium and pressure sensitive and heat sensitive color developing medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-color recording medium, which is so constituted as to obtain respective independent color developments on two primary colors and to allow to obtain the color development of a mixed color by the two primary colors. SOLUTION: This multi-color recording medium 10 consists of a support 12 and a color developing layer 14 formed on the surface of the support. The color developing layer includes at least one heat sensitive color developing component and a large number of pressure sensitive microcapsules, in each of which coloring material having a desired hue is sealed. Pressure and temperature color developing characteristics, which develops color by being destructed under the predetermined pressure and in a first temperature range, is given to the pressure sensitive microcapsule. Pressure color developing characteristics, which develop color with a hue different from that of the coloring material within a second temperature range lying between a first temperature included in the first temperature range and a second temperature exceeding the upper limit temperature in the first temperature range, is given to the heat sensitive color developing component.

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, and the present invention relates to a pressure-sensitive and heat-sensitive coloring medium applicable to the multi-color recording medium. Regarding the medium.

[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 additive-type multi-color thermosensitive recording medium, the low-temperature-side leuco dye of the first and second leuco dyes (that is, the leuco dye for magenta coloring in the above example) is formed. The temperature is generally 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 coloring temperature of the low-temperature side leuco dye is set to, for example, 80 ° C., if the multi-color thermal recording medium is inadvertently exposed to a temperature of 80 ° C. or more, false coloring such as background stains may occur there. This is because it will occur. On the other hand, when the color development temperature of the low-temperature side leuco dye is set to at least 100 ° C,
It is necessary to set the coloring temperature of the high-temperature side leuco dye (that is, the leuco dye for cyan coloring in the above example) to a high temperature sufficiently exceeding the coloring temperature of the low-temperature side leuco dye (at least 100 ° C.). . This is because 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 low-temperature leuco dye will have a low concentration when the low-temperature leuco dye is colored. This is because a phenomenon of coloring, that is, so-called fogging 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
No. 4, in the color-added multi-color thermal recording medium as described above, the temperature difference between the coloring temperature of the low-temperature coloring leuco dye and the coloring temperature of the high-temperature coloring leuco dye is relatively close. It is also disclosed that a high-temperature-side colored leuco dye is encapsulated in heat-sensitive microcapsules in order to prevent the occurrence of fog. That is, when the heat-sensitive microcapsules are heat-melted at a predetermined temperature (the color-forming temperature of the high-temperature coloring leuco dye), the high-temperature coloring leuco dye flows out and reacts with the color developer to form a color reaction. Until the capsules are melted by heat, the color formation of the high-temperature side leuco dye can be prevented, so that the fog during the color formation of the low-temperature side leuco dye is prevented.

[0007]

In the above-described additive multicolor recording medium, only one of the two basic colors can be independently formed, but the other basic colors are independently formed. It cannot be colored. 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 color-forming function and efficiency.

It is pointed out that another problem with the conventional multi-color thermal paper described above is that a desired color may not be obtained. For example, various types of magenta colors are also known, but the magenta colors are limited to those obtained with leuco dyes,
Furthermore, when the combination with leuco dyes of other colors is taken into consideration, the selection range of the magenta color can be further narrowed in consideration of the temperature conditions. Some users of the multi-color heat-sensitive recording medium desire to obtain a color having a desired hue for at least one color.
However, unless the desired hue can be obtained with only one type of leuco dye, it is impossible to meet the demands of such users. On the other hand, even if a magenta leuco dye is appropriately mixed and a magenta color of a desired color is obtained,
The desired hot melt temperature is not always obtained for the blended leuco dye. Further, in the case of obtaining three or more colors, the range of choice of leuco dye is further narrowed, and it may be said that it is almost impossible to obtain a desired color for a certain color.

Accordingly, an object of the present invention is to provide a multi-color recording medium configured to obtain independent colors for each of two basic colors and to obtain a mixed color by the two basic colors. is there.

Another object of the present invention is to provide a multi-color recording medium configured to obtain independent colors for each of the two basic colors and to obtain a mixed color by the two basic colors. Another object of the present invention is to provide a multi-color recording medium capable of realizing a hue of an arbitrary hue for one of the two basic colors.

It is a further object of the present invention to provide a pressure-sensitive and heat-sensitive coloring medium used for a multicolor recording medium as described above.

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 multi-color heat-sensitive recording medium disclosed in Japanese Patent Publication No. 4 (1999), even if the color-forming temperature of the high-temperature coloring leuco dye can be set to a relatively low temperature side, the low-temperature coloring leuco dye can be used as a base stain. In order to prevent erroneous coloring, the coloring temperature must still be set at a high temperature of at least 100 ° C.

Therefore, another object of the present invention is to provide a multi-color recording medium of the above-mentioned type, 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.

[0014]

According to one aspect of the present invention, there is provided a multicolor recording medium comprising a support and a color-forming layer formed on the surface of the support. The color-forming layer includes at least one heat-sensitive color-forming component and a number of pressure-sensitive microcapsules in which a colorant having a desired hue is encapsulated and uniformly distributed. The pressure-sensitive microcapsules are provided with a pressure-temperature coloring characteristic which is broken under a predetermined pressure and within a first temperature range to form a color, and the thermosensitive coloring component is included in the first temperature range. In a second temperature range between a first temperature and a second temperature exceeding an upper limit temperature of the first temperature range, a temperature color developing characteristic of developing a color different from the color material in a second color range is provided. Given.

As described above, in the multicolor recording medium, the color mixture of the coloring by the coloring material of the pressure-sensitive microcapsules and the coloring by the thermosensitive coloring component is between the first temperature and the upper limit temperature of the first temperature range. In addition, only the coloring by the thermosensitive coloring component is obtained between the upper limit temperature of the first temperature range and the second temperature.

The first temperature range is set with respect to the thickness of the coloring layer, the content of the filler in the coloring layer, the average particle size of the pressure-sensitive microcapsules, the pressure resistance of the pressure-sensitive microcapsules, the material and the support of the support. This can be done by changing at least one parameter selected from a group of parameters consisting of body surface roughness. The lower limit temperature of the first temperature range is preferably set to 100 ° C. or lower.

In the multicolor recording medium according to the present invention, the color-forming layer may further contain another heat-sensitive color-forming component in addition to the heat-sensitive color-forming component. In the temperature range of 3, a temperature color developing characteristic is provided which develops a color different from the two hues.

Preferably, the two thermosensitive coloring components comprise a leuco dye, wherein the color-forming layer includes a developer component of the leuco dye. In this case, the first temperature is the color development start temperature of the leuco dye having the thermosensitive coloring characteristic defined by the second temperature range, and the second temperature is the leuco dye having the thermosensitive coloring characteristic defined by the third temperature range. This is the color development start temperature of the dye. Preferably, the leuco dye having the thermosensitive coloring property defined by the third temperature range is a leuco dye for black coloring. The coloring material encapsulated in the pressure-sensitive microcapsules may be a coloring material based on a leuco dye, in which case the developer undergoes thermal melting at the lower limit of the first temperature range.

In the multicolor recording medium according to the present invention, the coloring layer has a two-layer structure comprising a pressure-sensitive thermosensitive coloring layer containing the pressure-sensitive microcapsules and a thermosensitive coloring layer containing a thermosensitive coloring component. be able to. When the color material encapsulated in the pressure-sensitive microcapsules is a color material based on a leuco dye, the pressure-sensitive thermosensitive coloring layer contains a developer component of the leuco dye, and the developer component is First
At the lower limit of the temperature range.

The heat-sensitive color-forming layer may contain another heat-sensitive color-forming component different from the heat-sensitive color-forming component contained in the heat-sensitive color-forming layer, and the other heat-sensitive color-forming component has a temperature higher than the second temperature. In the third temperature range, there is provided a temperature coloring characteristic in which coloring is performed in a hue different from the two hues. When the two thermosensitive coloring components comprise a leuco dye, each of the pressure-sensitive thermosensitive coloring layer and the thermosensitive coloring layer contains a developer component of the leuco dye. In this case, the first temperature is the color development start temperature of the leuco dye contained in the thermosensitive coloring layer, and the second temperature is the color development start temperature of the leuco dye contained in the pressure sensitive thermosensitive coloring layer. You. The leuco dye contained in the pressure-sensitive thermosensitive coloring layer can be a leuco dye for black coloring.

According to another aspect of the present invention, there is provided a pressure-sensitive thermosensitive coloring medium, comprising a support and a pressure-sensitive thermosensitive coloring layer formed on the support. The pressure-sensitive thermosensitive coloring layer is formed as a number of pressure-sensitive microcapsules evenly distributed in a binder material, and a color material having a desired hue is sealed in the pressure-sensitive microcapsules. The pressure-sensitive microcapsules are provided with a pressure-temperature coloring characteristic that is broken under a predetermined pressure and within a predetermined temperature range to develop a color, and the setting of the temperature range includes the thickness of the pressure-sensitive thermosensitive coloring layer, Filler content in the pressure-sensitive thermosensitive coloring layer,
This is performed by changing at least one parameter selected from the group consisting of the average particle size of the pressure-sensitive microcapsules, the pressure resistance of the pressure-sensitive microcapsules, the material of the support, and the surface roughness of the support.

In the pressure-sensitive thermosensitive coloring medium according to the present invention,
When the color material encapsulated in the pressure-sensitive microcapsules is a color material based on leuco dye, the binder material is a color developer of the color material, and the color developer is at a lower limit temperature in a predetermined temperature range. It will undergo thermal melting.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a multi-color 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 multicolor recording medium according to the present invention is indicated generally by the reference numeral 10, wherein the multicolor recording medium 10 comprises a suitable support such as polyethylene phthalate. It comprises a sheet 12 made of resin (PET) and a coloring layer 14 applied to one surface of the sheet 12. The coloring layer 14 includes a pressure-sensitive and heat-sensitive coloring layer 16P formed on the surface of the sheet 12 and a heat-sensitive and coloring layer 16P formed on the pressure-sensitive and heat-sensitive coloring layer 16P.
And T as a two-layer structure.

The pressure-sensitive and heat-sensitive coloring layer 16P is formed by uniformly distributing a large number of pressure-sensitive microcapsules 18 in a developer layer mainly composed of a leuco dye developer. Are conveniently indicated by the symbol "x" in FIG. Such a developer is available, for example, as K-5 manufactured by Asahi Denka Kogyo Co., Ltd.
Indicates 5 ° C. Although not shown in FIG. 1, acetoacetanilide is appropriately added as a sensitizer in the developer layer.

The pressure-sensitive microcapsules 18 are filled with, for example, a magenta coloring material.
A solution in which a leuco dye for magenta coloring is dissolved in an appropriate vehicle is used. In the present embodiment, a suitable transparent oil is used as a vehicle, and such a transparent oil is, for example, KKS manufactured by RKS (Rutgers Kureha Solvents GmbH).
It is available as MC-113 (2,7 diisopropyl naphthalene). As the magenta coloring leuco dye, for example, Red-3 manufactured by Yamamoto Kasei Co., Ltd. can be used.
That is, in the present embodiment, the pressure-sensitive microcapsules 18
Red for KMC-113 as a magenta color material to be enclosed in
-3 is used. In FIG. 1, the magenta-based coloring 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 suitable amino resin (thermosetting resin). Such a pressure-sensitive microcapsule 18 can be manufactured by a well-known microcapsule manufacturing method such as an in situ polymerization method.
μm to about 6 μm, and the thickness of the wall film is such that the pressure-sensitive microcapsules 18 can be broken under a pressure of 0.35 MPa or more accompanied by a shearing force, and furthermore, the heat resistance temperature is under no load condition. At about 300 ° C.

The pressure-sensitive microcapsules 18 which can be broken under a pressure of 0.35 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 Red-3 ... 3 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… 14 g Formalin… 36 g Purified water… 50 g (Note that formalin is a 2% sodium hydroxide aqueous solution and pH
37% formaldehyde prepared in 9 is used. 36 g of this formalin and 14 g of melamine are mixed and heated to 70 ° C.
After the melamine is dissolved, add 50 g of purified water and stir, (C)
(A melamine-formalin prepolymer aqueous solution was obtained)

2) Next, (A) a magenta color material solution and (B) an aqueous protective colloid 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 stirred slowly 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.

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 0.35 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.

The thermosensitive coloring layer 16T is composed of a leuco dye component and a developer component. In FIG. 1, the leuco dye component is represented by a symbol “□”, and the developer component is represented by a symbol “x”. As the leuco dye component “□”, a leuco dye for cyan coloring having a heat melting temperature (coloring temperature) of about 147 ° C. is used. Such a leuco dye for cyan coloring is available as, for example, Blue220 manufactured by Yamada Chemical Co., Ltd. It is. The developer component “×” is composed of a developer having a heat melting temperature of about 145 ° C.,
Such a developer is available as Asahi Denka Kogyo K-5. In addition, although not shown in FIG.
To 6T, stearic acid amide is appropriately added as a sensitizer.

Next, a production example of the sheet of the present invention will be described below. To form the pressure-sensitive and heat-sensitive coloring layer 16P, a composition liquid A having the composition shown in the following table is prepared. Composition parts by weight (1) Aqueous dispersion of 25 W% microcapsules… 1.0 (2) Aqueous dispersion of 20 W% K-5… 1.0 (3) Aqueous dispersion of 16 W% acetoacetanilide… 0.5 (4) 20 W% PVA ( 0.5 aqueous solution having a polymerization degree of 500) Here, the composition (1) is added
Was added and dispersed (suspended) by 25% by weight. The composition (2) is obtained by adding and dispersing (suspending) 20% by weight of K-5 (developing agent) in purified water, and this developing agent is a powder having an average particle diameter of 1 μm or less. Composition (3) is obtained by adding 16% by weight of acetoacetanilide (sensitizer) to purified water and dispersing (suspending) the same. This sensitizer is also a powder having an average particle size of 1 μm or less. Composition (4) is obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water and dissolving it.

The above composition A is applied to a sheet (PET) 12 with a Meyer bar No. 3 and dried to obtain a pressure-sensitive thermosensitive coloring layer 16P as shown in FIG. When the above composition liquid A is applied using the Meyer bar No. 3, an application amount of about 1 to 3 grams per square meter is obtained. In addition, as a sheet (PET) 12,
One with a thickness of 0.188 mm is used.

The thus obtained pressure-sensitive and heat-sensitive coloring layer 1
Since 6P contains acetoacetanilide as a sensitizer, the thermal melting temperature of the color developer (K-5) is from about 145 ° C to about 90 ° C.
To be lowered. The polyvinyl alcohol (PVA) having the composition (4) functions as a binder, whereby the pressure-sensitive and heat-sensitive coloring layer 16P is integrated and fixed to the sheet 12.

To form the thermosensitive coloring layer 16T, a composition B having the composition shown in the following table is prepared. Composition parts by weight (1) Aqueous dispersion of 17W% Blue220… 1.0 (2) Aqueous dispersion of 20W% K-5… 1.0 (3) Aqueous dispersion of 16W% stearamide… 0.5 (4) 20W% PVA ( Aqueous solution having a polymerization degree of 500)... 0.5 Here, composition (1) is obtained by adding and dispersing (suspending) Blue220 (leuco dye for cyan coloring) in purified water by 17% by weight. Blue220 itself has an average particle size. It is a powder of 1 μm or less. Composition (2) is obtained by adding 20% by weight of K-5 (a color developer) to purified water and dispersing (suspending). Composition (3) is obtained by adding 16% by weight of stearic acid amide (sensitizer) to purified water and dispersing (suspending) the same, and the sensitizer itself is a powder having an average particle size of 1 μm or less. Composition (4) is obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water and dissolving it.

The above-mentioned composition B is applied to the pressure-sensitive thermosensitive coloring layer 16P with the Meyer bar No. 3 and dried to obtain a thermosensitive coloring layer 16T as shown in FIG.
As in the case of forming the pressure-sensitive and heat-sensitive coloring layer 16P, when the composition liquid B is applied using the Meyer bar No. 3, an application amount of about 1 to 3 grams per square meter is obtained.

The thermosensitive coloring layer 16T thus obtained
Contains stearic acid amide as a sensitizer,
The color onset temperature of the cyan color leuco dye (Blue 220) is lowered to about 105 ° C. by the eutectic action.

Referring to FIG. 2, there is schematically shown an image recording apparatus for recording a color image on the multi-color recording medium 10 configured as described above, and this image recording apparatus is configured as a thermal line printer. You. According to such a thermal line printer, a multicolor recording medium 10 can be used to form a color image of two basic colors, magenta and cyan, and a mixed color of magenta and cyan, that is, a color image of blue. It is possible to record.

As shown in FIG. 2, 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. 2 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. A thermal head 30 is mounted on the thermal head support 28, and the thermal head 30
A number n of electric resistance elements, that is, heating elements, are arranged in a straight line along the direction traversing the zero movement path.

Referring to FIG. 3, some of the n heating elements included in the thermal head 30 are indicated by reference numerals R1, R2 and R3. As shown in the figure, n heating elements R1, R2, R3,... Rn are connected to a thermal head driving circuit 31, and the thermal head driving circuit 31 causes the n heating elements R1, R2, R3,. .. Rn 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 (R
1, R2, R3,... Rn) have an exothermic temperature of about 90 ° C.
When the color pixel data is pixel data containing both magenta and cyan, that is, blue pixel data, the heating temperature of the corresponding heating element (R1, R2, R3,... Rn) is set to about 120 ° C. Further, as a characteristic print control of the present invention, when the color pixel data is only the cyan pixel data, the corresponding heating elements (R1, R2, R3,.
The heat generation temperature of Rn) is set to about 180 ° C., and the color development is controlled. The coloring process will be described later in detail.

As shown in FIG. 2, a platen roller 32 is applied to the thermal head 30, and a pressure applying spring means 34 is combined with the platen roller 32. The pressure applying spring means 34 is configured to apply, for example, about 1.4 MPa to the platen roller 32, whereby the platen roller 32 is pressed against the thermal head 30 at a pressure of about 1.4 MPa.

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. 2, reference numeral 36 indicates a control circuit board for controlling the operation of the thermal head drive circuit 31 (FIG. 3), and reference numeral 38 indicates a power supply device.
The power supply 38 supplies power to the heating elements of the thermal head 30, the control circuit board 36, and the like.

As described above, when recording a color image, the multi-color recording medium 10 is introduced into the inlet 22. At this time, the orientation of the multi-color recording medium 10 is such that the color-forming layer 14 side generates heat of the thermal head 30. Element R1,
Rn, R3,... Rn.

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 using the above-described recording apparatus.

When the multi-color recording medium 10 is passed between the thermal head 30 and the platen roller 32, the coloring layer 14 of the multi-color recording medium 10 is heated by the heating element R of the thermal head 30 due to the pressure applying spring means 34.
1, R2, R3,... Rn receive a pressure of about 1.4 MPa accompanied by shearing force. When each heating element is not energized, that is, when each heating element is at room temperature, about 1.4 MPa is applied. The pressure of MPa is prevented from being directly applied to the microcapsules 18 by being blocked by the coloring layer 14 presenting a solid phase.

However, when one of the heating elements R1, R2, R3,... Rn of the thermal head 30 is energized based on the magenta pixel data, the energized heating element is heated to about 90 ° C. as described above. Let me do. At this time, the developer component "x" in the thermosensitive coloring layer 16T is heat-softened due to the eutectic action with the sensitizer (stearic acid amide), so that the heating element is provided as shown in FIG. Invade 14 Further, the heating temperature of the heating element of about 90 ° C. extends to the pressure-sensitive and heat-sensitive coloring layer 16P.
The developer component "x" in P is also melted due to the eutectic action with the sensitizer (acetoacetanilide). Thus,
A pressure of about 1.4 MPa, which greatly exceeds the breaking pressure of 0.35 MPa, is applied to the pressure-sensitive microcapsules 18 by a heating element, whereby the pressure-sensitive microcapsules 18 are broken, and a magenta-based coloring material is released therefrom. You.

As is clear from the above description, the pressure coloring property of the pressure-sensitive and heat-sensitive coloring layer 16P is obtained by the wall film of the pressure-sensitive microcapsule 18, and the temperature coloring property of the developer in the coloring layer 14 is It is obtained by the temperature characteristics of the components and the sensitizer components.

As described above, the magenta coloring leuco dye released from the pressure-sensitive microcapsules 18 is dissolved in the transparent oil (KMC-113), and thus immediately becomes the developer component "x". A magenta color is formed by a color-forming reaction, so that magenta-colored dots are formed on the color-forming layer 14. When the heating temperature of the heating element of the thermal head 30 is about 90 ° C., the temperature is the color development start temperature (1) of the cyan color leuco dye component “□” in the thermosensitive coloring layer 16T.
05 ° C.) or lower, so that cyan coloring does not occur.

The heating elements R1, R of the thermal head 30
When any one of 2, R3,... Rn is energized based on the blue pixel data, the energized heating element is heated to about 120 ° C. as described above. Both the developer components “x” of the color forming layer 16P are thermally fused. The heating temperature of the heating element is about 120 ° C. The color development temperature of the leuco dye component “□” for cyan color development is 10
In this case, the leuco dye component “□” for cyan coloring is heated and melted due to the eutectic action of the developer (K-5) and the sensitizer (stearic amide). Thus, cyan is developed by the color development reaction with the developer. On the other hand, a pressure of about 1.4 MPa, which greatly exceeds the breaking pressure of 0.35 MPa, is directly applied to the pressure-sensitive microcapsules 18 by the heating element, so that the pressure-sensitive microcapsules 18 are broken, and as a result, the magenta color Magenta coloring by the material is obtained. Thus, blue coloring dots are formed on the coloring layer 14 by mixing the colors of cyan and magenta.

When one of the heating elements R1, R2, R3,... Rn of the thermal head 30 is energized based on cyan pixel data as a characteristic color development control of the present invention, the energized heating element is described above. As described above, the developer component is heated to about 180 ° C., and at this time, the developer components “x” of both the thermosensitive coloring layer 16T and the pressure-sensitive thermosensitive coloring layer 16P are thermally fused. Since the heating temperature of the heating element at about 180 ° C is 105 ° C or higher of the leuco dye component for cyan coloring “□”, the leuco dye component for cyan coloring “□” is also a developer.
It is hot-melted due to the eutectic action of (K-5) and a sensitizer (stearic acid amide), and develops cyan by a color-forming reaction with the developer. On the other hand, the pressure-sensitive microcapsules 18 are to be destroyed because a pressure of about 1.4 MPa, which greatly exceeds the breaking pressure of 0.35 MPa, is applied by the heating element. However, surprisingly, when the heating element of the thermal head 30 is instantaneously heated to a temperature exceeding the predetermined temperature (here, 180 ° C.), the pressure-sensitive microcapsule 18 is subjected to a pressure of about 1.4 MPa. Despite this, the color of magenta is no longer confirmed. Thus, when the heating element of the thermal head 30 is heated to 180 ° C.,
In the coloring layer 14, only cyan coloring dots are formed.

When the heating element of the thermal head 30 is heated to 180 ° C., the pressure-sensitive microcapsules 18
The reason for whether or not it can escape from destruction under a pressure of 1.4 MPa is presumed as follows from experiments performed by the present inventors.
That is, when the heat generating element is at a relatively low temperature, heat to the color forming layer 14 is mainly transmitted by heat conduction, but a high temperature is instantaneously applied to the color forming layer 14 of the multi-color recording medium 10 by the heat generating element of the thermal head 30. Then, in the form of heat transmission to the coloring layer 14 by the heating element, the ratio of heat radiation is higher than that of heat conduction, and the sensitizer, the developer and the leuco dye for cyan coloring are instantaneously brought into a high heat melting state. Since the fluidity is increased around the pressure-sensitive microcapsules 18, sufficient pressure is not applied to the pressure-sensitive microcapsules 18 sandwiched between the sheet 12 and the heating element, and the microcapsules 1
It is probable that No. 8 slipped out of it without being destroyed, or sneaked into the fluidized color forming layer and did not work with sufficient breaking shear pressure.

FIG. 5 shows the results of experiments conducted by the inventor. In this experiment, the set pressure of the pressure applying spring means 34 of the recording device was set to 0.35 MPa and 2.8 MPa.
a and the respective heating temperatures of the heating elements R1, R2, R3,.
When the temperature was changed between 200 ° C. and 200 ° C., the color of the coloring dots obtained on the coloring layer 14 was examined.

In the graph shown in FIG. 5, a hatched area indicated by "MA" indicates a magenta coloring area, a hatched area indicated by "CY" indicates a cyan coloring area, and a magenta coloring area "MA" and a cyan coloring area. An intersection area “MA / CY” overlapping with “CY” indicates a blue coloring area. As is clear from the graph, when the set pressure of the pressure applying spring means 34 is 0.35 MPa,
When the pressure applied to the color-forming layer 14 of the multi-color recording medium 10 by the heating element is 0.35 MPa, the temperature range in which magenta-colored dots are obtained is defined as a temperature range between the temperature T1 and the temperature T2; The temperature range in which cyan coloring dots are obtained is defined as a temperature range equal to or higher than the temperature t1, and the temperature range in which blue coloring dots are obtained is defined as a temperature range between the temperature t1 and the temperature T2. Here, T1 and T2 correspond to 90 ° C. and 165 ° C., respectively, and t1 and t2 correspond to 105 ° C. and 200 ° C., respectively. The temperature t2 is a temperature for the convenience of defining the upper limit of the temperature range in which cyan color dots can be obtained.

As is clear from the graph of FIG. 5, when the heating temperature of the heating element of the thermal head 30 exceeds 165 ° C., even if the pressure applied to the coloring layer 14 is increased,
It can be seen that the pressure-sensitive microcapsules 18 are less likely to break. Thus, when the sensitizer, the developer and the leuco dye for cyan coloring each instantaneously become a high-temperature molten state and increase in fluidity, it acts like a lubricant,
As a result, if sufficient pressure is not applied to the pressure-sensitive microcapsules 18 sandwiched between the sheet 12 and the heating element, and the pressure-sensitive microcapsules 18 slide out or dive without being destroyed. I have to guess.

Various control parameters in the above-described printing apparatus are determined based on the graph of FIG. That is, the set pressure of the pressure applying spring means 34 is 1.4 MPa.
The set temperature of magenta color temperature 90 ° C. (t1), the set temperature of blue color temperature 120 ° C., and the set temperature of cyan color temperature 180 ° C. are based on the graph of FIG.

In order to confirm the slip-through phenomenon of the pressure-sensitive microcapsules 18 as described above, the inventor uses a multi-color recording medium in which the layer thickness of the coloring layer 14 is larger than that described above as a comparative example. An experiment similar to the above-described experiment was performed on the multicolor recording medium of the comparative example. That is, the pressure-sensitive and heat-sensitive coloring layer 16P and the heat-sensitive coloring layer 16T of the above-mentioned multi-color recording medium are each coated with the above-described composition liquid A and composition liquid B using a Meyer bar No. 3 at about 1 to 3 grams per square meter. The pressure-sensitive and heat-sensitive coloring layers and the heat-sensitive coloring layers of the multicolor recording medium of the comparative example were formed using the Mayer bar No. 6, and the above-described composition liquid A and composition liquid B were each formed in a single coating amount. It was formed with a coating weight of about 4 to 6 grams per square meter. Experimental results for the multicolor recording medium of the comparative example are shown in the graph of FIG.

In the graph of FIG. 6, as in the case of the graph of FIG. 5, "MA", "CY" and "MA / CY"
Indicates a magenta coloring region, a cyan coloring region, and a blue coloring region, respectively. As is apparent from FIG.
It can be seen that as the thickness of the layer 4 increases, the area where the pressure-sensitive microcapsules 18 can be broken, that is, the magenta coloring area “MA” is further reduced. This is because, when the color-forming layer 14 is thicker, the pressure-sensitive microcapsules 18 are more easily escaped from the space between the sheet 12 and the heating element together with the surrounding developer and the like that have flowed in a high-melting state before being sandwiched between the sheet 12 and the heating element. It is considered to be. Thus, the multi-color recording medium 10
The color developing characteristics of the three colors (magenta, blue and cyan) can be controlled by appropriately adjusting the layer thickness of the color forming layer 14.

The inventor further conducted an experiment on parameters for controlling the color development characteristics of the three colors of the multicolor recording medium described above. The results of the investigation are described below.

First, a liquid prepared by adding a filler component to the above-described composition liquid A was prepared. That is, 5W% Aerosil as a filler component
An aqueous dispersion of 200 (manufactured by Nippon Aerosil Co., Ltd.) was prepared, and 2.0 parts by weight of this filler dispersion was added to the above-described composition liquid A to obtain a composition liquid A1. The composition A1 was applied to a sheet (PET) 12 with a Meyer bar No. 6 at a rate of about 4 to 6 per square meter.
To form a pressure-sensitive and heat-sensitive coloring layer 16P, and then the composition B is applied to the pressure-sensitive and heat-sensitive microcapsule layer 16P with a Meyer bar No. 6 at a coating amount of about 4 to 6 grams per square meter. Heat-sensitive coloring layer 16
T was formed and a multicolor recording medium was created. An experiment similar to the above-described experiment was performed on such a multicolor recording medium. The experimental results are shown in the graph of FIG. This multi-color recording medium is the same as the above-described multi-color recording medium of the comparative example (FIG. 6) except that the coloring layer 14 contains a filler.

In the graph of FIG. 7, as in the case of the graph of FIG. 5, "MA", "CY" and "MA / CY"
Indicates a magenta coloring region, a cyan coloring region, and a blue coloring region, respectively. As is apparent from FIG.
It can be seen that when the filler is added to No. 4, the magenta coloring area “MA” becomes wider than the case shown in FIG. It is considered that the reason is that slippage of the pressure-sensitive microcapsules 18 between the sheet 12 and the heating element is suppressed by the filler in the coloring layer 14. Thus,
The coloring properties of the three colors (magenta, blue and cyan) of the multicolor recording medium 10 can be controlled by appropriately adjusting the content of the filler in the coloring layer 14.

Further, a composition liquid A2 was obtained by replacing the pressure-sensitive microcapsules 18 having an average particle diameter of 5 μm in the composition liquid A with an average particle diameter of 3 μm. The composition A2 is applied on a sheet (PET) 12 with a Meyer bar No. 6 at a coating amount of about 4 to 6 grams per square meter to produce a pressure-sensitive thermosensitive coloring layer 1.
6P, and then the above-mentioned composition B is applied with a Meyer bar No. 6 on the pressure-sensitive thermosensitive coloring layer 16P at a coating amount of about 4 to 6 grams per square meter to form a thermosensitive coloring layer 16T. Thus, a multi-color recording medium was created. An experiment similar to the above-described experiment was performed on such a multicolor recording medium. The experimental results are shown in the graph of FIG. The multi-color recording medium is the same as the multi-color recording medium of the above-described comparative example (FIG. 6) except for the difference in the average particle size of the used pressure-sensitive microcapsules.

In the graph of FIG. 8, "MA", "CY" and "MA / CY"
Indicates a magenta coloring region, a cyan coloring region, and a blue coloring region, respectively. As is apparent from FIG. 6, when the average particle size of the pressure-sensitive microcapsules 18 in the pressure-sensitive and heat-sensitive coloring layer 16P becomes smaller, the magenta coloring region “MA” may be further narrowed as compared with the case shown in FIG. I understand. The reason is that the smaller the average particle size of the pressure-sensitive microcapsules 18 becomes, the more easily the pressure-sensitive microcapsules 18 slide out from between the sheet 12 and the heat-generating element, and also the more the breaking pressure from the heat-generating element is reduced. It is thought that it is hard to receive. Thus, the color development characteristics of the three colors (magenta, blue and cyan) of the multicolor recording medium 10 can be controlled by appropriately adjusting the average particle size of the pressure-sensitive microcapsules 18.

Further, a multicolor recording medium was prepared by replacing the sheet (PET) 12 with a coated paper having a thickness of 0.072 mm (Beck smoothness of 1000 or more). That is, a Meyer bar on coated paper
The composition A described above with No. 6 was applied at a coating amount of about 4 to 6 grams per square meter to obtain a pressure-sensitive thermosensitive coloring layer 1
6P is formed, and the above-mentioned composition B is applied on the pressure-sensitive thermosensitive coloring layer 16P using a Meyer bar No. 6 at a coating amount of about 4 to 6 grams per square meter to form the thermosensitive coloring layer 16T. To form a multicolor recording medium. With respect to such a multi-color recording medium, an experiment similar to the above-described experiment was performed up to a pressure of 4.2 MPa. The experimental results are shown in the graph of FIG. The multicolor recording medium is the same as the multicolor recording medium of the above-described comparative example (FIG. 6) except that coated paper is used instead of the sheet (PET) 12 as a support.

In the graph of FIG. 9, "MA", "CY" and "MA / CY"
Indicates a magenta coloring region, a cyan coloring region, and a blue coloring region, respectively. As is clear from the figure, the sheet (P
When the coated paper is used instead of (ET) 12, the magenta coloring area “MA” is further narrowed as compared with the case shown in FIG. The reason is that the material of the coated paper is softer than that of the sheet (PET) 12 and the pressure-sensitive microcapsules 18 easily enter the fiber structure of the coated paper when subjected to pressure from the heating element and are easily protected from destruction. It is thought that there is not. Thus, the color development characteristics of the three colors (magenta, blue and cyan) of the multi-color recording medium 10 can be controlled by appropriately changing the material of the support.

Further, an investigation experiment was conducted on the case where the breaking strength of the pressure-sensitive microcapsules 18 was changed. More specifically, in the production example of the pressure-sensitive microcapsules 18 described above, the amount of the wall film material, that is, melamine in the melamine-formalin prepolymer aqueous solution was 14 g, but the amount of melamine was reduced by 20% to 11.2 g. Pressure sensitive microcapsules were produced. The wall film of this pressure-sensitive microcapsule is thinner than the pressure-sensitive microcapsule 18, and the pressure resistance is correspondingly weaker. The composition A3 was obtained by replacing the pressure-sensitive microcapsules 18 in the composition A described above with pressure-sensitive microcapsules having low strength. Composition solution A3 was applied on a 0.072 mm thick coated paper (Beck smoothness 1000) with Meyer bar No. 6.
A coating amount of about 4 to 6 grams per square meter is applied to form a pressure-sensitive and heat-sensitive coloring layer 16P, and then the above-mentioned composition B is applied onto the pressure-sensitive and heat-sensitive coloring layer 16P by using a Meyer bar No. 6. It was applied at a coverage of about 4 to 6 grams per square meter to form a thermosensitive coloring layer 16T, thereby producing a multicolor recording medium. An experiment similar to the above-described experiment was performed on such a multicolor recording medium. The experimental results are shown in the graph of FIG. In addition,
This multi-color recording medium is the same as the multi-color recording medium having color developing characteristics as shown in FIG. 9 except that a pressure-sensitive microcapsule having a low pressure-resistant strength is used for the pressure-sensitive and heat-sensitive coloring layer 16P.

In the graph of FIG. 10, as in the case of the graph of FIG. 5, "MA", "CY" and "MA / C
Y "indicates a magenta coloring region, a cyan coloring region, and a blue coloring region, respectively. As is clear from FIG. 9, when a pressure-sensitive microcapsule having a low pressure resistance is used, FIG.
It can be seen that the magenta coloring area “MA” spreads wider than the case shown in FIG. The reason for this is, of course, that if the pressure-resistant strength of the pressure-sensitive microcapsules decreases, the pressure-sensitive microcapsules are more likely to be broken. Thus, the multi-color recording medium 10
The color development characteristics of the three colors (magenta, blue and cyan) can be controlled by appropriately changing the pressure resistance of the pressure-sensitive microcapsules.

Further, an investigation experiment was conducted on the case where the surface roughness of the support 12 of the multicolor recording medium 10 was changed. More specifically, the above-described composition solution A is applied on a thermal transfer paper (0.072 mm thick) having a Beck smoothness of about 300 to 400 using a Meyer bar No. 6 at an application amount of about 4 to 6 grams per square meter. To form a pressure-sensitive thermosensitive coloring layer 16P, and then apply the above-mentioned composition B on the pressure-sensitive thermosensitive coloring layer 16P using a Meyer bar No. 6 at a coating amount of about 4 to 6 grams per square meter. Thermosensitive coloring layer 1
6T was formed, thereby producing a multicolor recording medium. An experiment similar to the above-described experiment was performed on such a multicolor recording medium. Figure 1 shows the experimental results.
1 is shown in the graph. This multi-color recording medium is the same as the multi-color recording medium having the coloring characteristics shown in FIG. 9 except that thermal transfer paper having a Beck smoothness of about 300 to 400 is used as the support 12. .

In the graph of FIG. 11, as in the case of the graph of FIG. 5, "MA", "CY" and "MA / C
Y "indicates a magenta coloring region, a cyan coloring region, and a blue coloring region, respectively. As is apparent from the figure, the surface of the support 12 (thermal transfer paper) having a rough surface is more magenta than the case shown in FIG. It can be seen that the “MA” spreads widely because the rougher the surface of the support 12 is, the more the pressure-sensitive microcapsules 18
2 and the heat-generating element. Thus, the color development characteristics of the three colors (magenta, blue and cyan) of the multicolor recording medium 10 can be controlled by appropriately changing the surface roughness of the support 12.

In short, by appropriately selecting the above-mentioned various control parameters, it is possible to give desired color-developing characteristics to the three colors (magenta, blue and cyan) of the multi-color recording medium 10, and thus it is possible to provide two colors. Not only the basic colors of magenta and cyan, but also
Even a color mixture of them, blue, can be developed.

Referring to FIG. 12, a second embodiment of a multi-color recording medium according to the present invention is indicated generally by the reference numeral 40, which multi-color recording medium 40 has a suitable support, for example a 0.072 mm thick substrate. Thermal transfer paper (Beck smoothness 400)
42, and a coloring layer 44 applied to one surface of the thermal transfer paper 42. The coloring layer 44 has a two-layer structure including a pressure-sensitive and heat-sensitive coloring layer 46P formed on the surface of the thermal transfer paper 42 and a heat-sensitive and coloring layer 46T formed on the pressure-sensitive and heat-sensitive coloring layer 46P.

The pressure-sensitive thermosensitive coloring layer 46P is formed by uniformly distributing a large number of pressure-sensitive microcapsules 48 in a thermosensitive coloring layer composed of a black leuco dye component and its developer component. In the above, the black leuco dye component is conveniently indicated by "△", and the developer component is conveniently indicated by "x". The black leuco dye is available, for example, as ETAC manufactured by Yamada Chemical Co., Ltd. The thermal melting temperature of this ETAC is about 208 ° C. The developer is available, for example, as K-5 manufactured by Asahi Denka Kogyo Co., Ltd. This K-5 has a heat melting temperature of about 145 ° C. Although not shown in FIG. 12, a low-melting-point stearamide having a relatively low purification degree is appropriately added as a sensitizer to the color developer layer.

The pressure-sensitive microcapsules 48 are the same as the pressure-sensitive microcapsules 18 used in the first embodiment. That is, Red-3 is added to the pressure-sensitive microcapsules 48KMC-113.
A magenta coloring material in which is dissolved is encapsulated, its average particle size is about 5 μm to 6 μm, and the thickness of its wall film is 0.35 MPa or more with pressure-sensitive microcapsules 48 accompanied by shearing force. It is such that it can be broken under pressure.

The thermosensitive coloring layer 46T is composed of a leuco dye component and a developer component. In FIG. 12, the symbol “○” indicates the leuco dye component and the symbol “x” indicates the developer component.
Indicated by About 243 ° C for the leuco dye component “○”
An emerald green color-forming leuco dye having a heat melting temperature of, for example, is used. Such an emerald green color-forming leuco dye is available as, for example, GREEN 118 manufactured by Yamamoto Kasei Co., Ltd. As the developer component "x", K-5 is used as in the case of the pressure-sensitive and heat-sensitive coloring layer 46P. In addition,
Although not shown in FIG. 1, as in the case of the pressure-sensitive thermosensitive coloring layer 46P, stearic acid amide is appropriately added to the thermosensitive coloring layer 46T as a sensitizer.

To form the pressure-sensitive and heat-sensitive coloring layer 46P, a composition C having the composition shown in the following table is prepared. Composition parts by weight (1) 25 W% aqueous dispersion of microcapsules… 1.0 (2) 17 W% aqueous dispersion of ETAC… 1.0 (3) 20 W% K-5 aqueous dispersion… 1.0 (4) 16 W% low melting point stearin Aqueous dispersion of acid amide: 0.5 (5) Aqueous solution of 20 W% PVA (polymerization degree: 500) ... 0.5 Here, composition (1) is added to purified water with pressure-sensitive microcapsules 18
Was added and dispersed (suspended) by 25% by weight. Composition (2) is obtained by adding and dispersing (suspending) 17% by weight of ETAC (leuco dye for black coloring) to purified water, and ETAC itself is a powder having an average particle diameter of 1 μm or less.
The composition (3) is obtained by adding and dispersing (suspending) K-5 (a color developer) in purified water by 20% by weight, and the color developer is a powder having an average particle diameter of 1 μm or less. Composition (4) is obtained by adding 16% by weight of low-melting-point stearamide (sensitizer) to purified water and dispersing (suspending) the same. This sensitizer is also a powder having an average particle size of 1 μm or less. . Composition (5) is obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water and dissolving it.

By applying the above composition liquid C on a coated paper 42 with a Meyer bar No. 6 and drying it,
A pressure-sensitive and heat-sensitive coloring layer 46P as shown in FIG. 12 is obtained.
When the above composition liquid C is applied using the Meyer bar No. 6, an application amount of about 4 to 6 grams per square meter is obtained.

The pressure-sensitive and heat-sensitive coloring layer 4 thus obtained
Since 6P contains low-melting-point stearamide as a sensitizer, the heat melting temperature of the developer (K-5) is from about 145 ° C to about 9 ° C.
The temperature is lowered to 0 ° C., and the color development start temperature of the black color leuco dye (ETAC) is further lowered to about 180 ° C. by the eutectic action. The polyvinyl alcohol (PVA) having the composition (5) functions as a binder, whereby the pressure-sensitive and heat-sensitive coloring layer 46P is integrated and fixed to the thermal transfer paper 42.

For forming the thermosensitive coloring layer 46T, a composition D having the composition shown in the following table is prepared. Composition Weight part (1) Aqueous dispersion of 17W% GREEN118… 1.0 (2) Aqueous dispersion of 20W% K-5… 1.0 (3) Aqueous dispersion of 16W% stearamide… 0.5 (4) 20W% PVA ( Aqueous solution with a polymerization degree of 500)… 0.5 Here, composition (1) is obtained by adding 17% by weight of GREEN 118 (leuco dye for emerald green coloring) to purified water and dispersing (suspending) the GREEN 118 itself. Diameter 1
It is a powder of μm or less. Composition (2) is obtained by adding 20% by weight of K-5 (a color developer) to purified water and dispersing (suspending). Composition (3) is obtained by adding 16% by weight of stearic acid amide (sensitizer) to purified water and dispersing (suspending) the same, and the sensitizer itself is a powder having an average particle size of 1 μm or less. Composition (4) is a solution obtained by adding 20% by weight of PVA (polyvinyl alcohol) to purified water.

The composition D is applied to the pressure-sensitive and heat-sensitive coloring layer 46P with a Meyer bar No. 6 and dried to obtain a heat-sensitive coloring layer 46T as shown in FIG. As in the case of the formation of the pressure-sensitive and heat-sensitive coloring layer 46P, when the composition D is applied using the Meyer bar No. 6, an application amount of about 4 to 6 grams per square meter is obtained.

The heat-sensitive coloring layer 46T thus obtained
Contains stearic acid amide as a sensitizer,
The color development onset temperature of the leuco dye for emerald green coloring (GREEN 118) is lowered to about 105 ° C by eutectic action.

The color development characteristics of the multicolor recording medium 40 shown in FIG. 12 were also examined by using a recording apparatus as shown in FIGS. That is, the set pressure of the pressure applying spring means 34 is changed between 0.35 MPa and 2.8 MPa, and the heat generating elements R1, R2,
The color of the coloring dots obtained on the coloring layer 44 when the respective exothermic temperatures of R3,... Rn were changed between 80 ° C. and 200 ° C. was examined. The results are shown in the graph of FIG.

In the graph shown in FIG.
The hatched area indicated by indicates a magenta coloring area, and "E
A hatched area indicated by “G” indicates an emerald green coloring area, and an intersection area “MA / E” where the magenta coloring area “MA” and the emerald green coloring area “EG” overlap.
“G” indicates a dark blue coloring region, and “BK” indicates a black coloring region.

As is clear from the graph of FIG. 13, when the pressure applied to the coloring layer 44 of the multicolor recording medium 40 by the heating element of the thermal head 30 is 0.5 MPa, the temperature range in which magenta coloring dots can be obtained is as follows. It is defined as a temperature range between the temperature TT1 and the temperature TT2. The temperature range in which emerald green coloring dots are obtained is defined as a temperature range equal to or higher than the temperature tt1, and the temperature range in which dark blue coloring dots are obtained is defined as a temperature range between the temperature tt1 and the temperature TT2. . Further, a temperature range in which black coloring dots can be obtained is defined as a temperature range equal to or higher than the temperature tt2. In the temperature range of the temperature tt2 or higher, emerald green coloring dots can be obtained, but the emerald green coloring dots are absorbed by the black coloring dots and cannot be visually recognized.

Thus, a multi-color image composed of four colors of magenta, emerald green, dark blue and black can be recorded on the multi-color recording medium 40 by using the above-described recording apparatus. That is, when the set pressure of the pressure applying spring means 34 is set to 1.4 MPa, for example, for each of the magenta coloring temperature and the dark blue coloring temperature, the temperature TT1 (95 ° C.) and the temperature TT2 (110 ° C.) It can be set, and for each of the emerald green coloring temperature and black coloring temperature, 165
C and 200 C can be set.

Next, the color forming process when a color image is recorded on the color forming layer 44 of the multi-color recording medium 40 will be described.

As in the case of the multi-color recording medium 10, when the multi-color recording medium 40 is passed between the thermal head 30 and the platen roller 32, the color-forming layer 44 of the multi-color recording medium 40 is 34, the heating elements R1, R
2, R3,... Rn receives a pressure of about 1.4 MPa accompanied by shearing force. When each heating element is not energized, that is, when each heating element is at room temperature, about 1.
The pressure of 4 MPa is impeded by the coloring layer 44 presenting a solid phase and is not directly applied to the microcapsules 48.

However, when one of the heating elements R1, R2, R3,... Rn of the thermal head 30 is energized based on the magenta pixel data, the energized heating element is heated to about 95 ° C. (TT1). Can be At this time, the developer component “x” in the thermosensitive coloring layer 46T is thermally softened due to the eutectic action with the sensitizer (stearic acid amide), so that the heating element enters the coloring layer 44. The heating temperature of the heating element of about 95 ° C. also reaches the pressure-sensitive and heat-sensitive coloring layer 46P, so that the developer component “x” in the pressure-sensitive and heat-sensitive coloring layer 46P is also a sensitizer (low melting point stearamide). Is melted due to the eutectic action with Thus, a pressure of about 1.4 MPa, which is much higher than the breaking pressure of 0.35 MPa, is applied to the pressure-sensitive microcapsules 48 by the heating element, whereby the pressure-sensitive microcapsules 48 are broken, from which the magenta-based color material is formed. Released.

As in the case of the first embodiment, the pressure coloring property of the pressure sensitive thermosensitive coloring layer 46P is obtained by the wall film of the pressure sensitive microcapsule 48, and the temperature coloring property of the pressure sensitive thermosensitive coloring layer 46P is the same as that of the coloring layer 44. Of the developer component and the sensitizer component.

As described above, the magenta coloring leuco dye released from the pressure-sensitive microcapsules 48 is dissolved in the transparent oil (KMC-113), so that the developer component immediately becomes “X”. A magenta color is formed by a color-forming reaction, so that magenta-colored dots are formed in the color-forming layer 44. When the heating temperature of the heating element of the thermal head 30 is about 95 ° C., the temperature is the thermal melting temperature of the leuco dye component “○” for emerald green coloring in the thermosensitive coloring layer 46T, that is, the color development starting temperature (105 ° C.). Emerald green coloring is not caused because:

Heating elements R1, R of thermal head 30
When any one of 2, R3,... Rn is energized based on the dark blue pixel data, the energized heating element becomes approximately 110 ° C.
(TT2), and the heat-sensitive coloring layer 46
T and the developer component “x” of both the pressure-sensitive thermosensitive coloring layer 46P
Is thermally melted. Since the heating temperature of the heating element at about 110 ° C. is equal to or higher than 105 ° C. of the leuco dye component for emerald green coloring “○”, in this case, the leuco dye component for emerald green coloring “○” is the developer (K -5) and a sensitizer (stearic acid amide) are heated and melted due to a eutectic action, and emerald green is formed by a color development reaction with the developer. On the other hand, pressure-sensitive microcapsules 48
In addition, since a pressure of about 1.4 MPa, which greatly exceeds the breaking pressure of 0.35 MPa, is directly applied by the heating element, the pressure-sensitive microcapsules 48 are broken, and as a result, magenta coloring by a magenta coloring material is obtained. . Thus, dark blue coloring dots are formed on the coloring layer 44 by mixing colors of emerald green and magenta.

Heating elements R1, R of thermal head 30
When any one of 2, R3,... Rn is energized based on the emerald green pixel data, the energized heating element is heated to about 165 ° C.
The developer components “x” of both the 6T and the pressure-sensitive and heat-sensitive coloring layer 46P are thermally fused. The exothermic temperature of the heating element is about 165 ° C. The leuco dye component for emerald green coloring “○”
In this case, the leuco dye component for emerald green coloring “グ リ ー ン” is a developer (K-
It is heated and melted due to the eutectic action of 5) and a sensitizer (stearic acid amide), and develops emerald green by a color development reaction with the developer. On the other hand, the pressure-sensitive microcapsules 48 also have a breaking pressure of about 1.4MP
Since the pressure of a is applied by the heating element, the pressure-sensitive microcapsules 48 should be destroyed, but the pressure-sensitive microcapsules 48 are protected from being destroyed for the reasons described above. Thus, the thermal head 3
When the heating element No. 0 is heated to 165 ° C., only emerald green coloring dots are formed on the coloring layer 44. When the heating temperature of the heating element of the thermal head 30 is about 165 ° C., the temperature is set to the pressure-sensitive thermosensitive coloring layer 46P.
Since the temperature is below the heat melting temperature of the leuco dye component “△” for black color formation, that is, the color formation start temperature (180 ° C.), black color formation does not occur.

Heating elements R1, R of thermal head 30
When any one of 2, R3,... Rn is energized based on the black pixel data, the energized heating element becomes approximately 200
° C, and at this time, the developer components “x” of both the thermosensitive coloring layer 46T and the pressure-sensitive thermosensitive coloring layer 46P are thermally fused. The heating temperature of the heating element at about 200 ° C is 180 ° C or higher for the leuco dye component for black coloring “△”, so the leuco dye component for black coloring “△” is sensitized with the developer (K-5). It is hot-melted due to the eutectic action with the agent (low-melting-point stearamide), and develops black by a color-forming reaction with the developer. On the other hand, about 200
Since the exothermic temperature of ℃ is 105 ° C or higher of the leuco dye component for emerald green coloring “○”, the leuco dye component for emerald green coloring “○” is also a developer (K-5) and a sensitizer (stearin). (E.g., acid amide), and is heat-melted due to the eutectic action, thereby forming an emerald green by a color development reaction with the color developer. However, since emerald green is absorbed by black, when the heating element of the thermal head 30 is heated to 200 ° C., black coloring dots are formed on the coloring layer 44.

Referring to FIG. 14, there is shown a modified embodiment of the second embodiment of the multi-color recording medium according to the present invention. 12, the same reference numerals are used for the same components as those shown in FIG.
The same reference numerals with dashes "" are used for the similar components corresponding to the components shown in FIG.

The multi-color recording medium 40 'shown in FIG.
However, a two-layered color-forming layer 44 'is formed on the thermal transfer paper 42. However, the color-forming layer 44' includes a heat-sensitive color-forming layer 46T 'formed directly on the thermal transfer paper 42 and a heat-sensitive color-forming layer 46'.
And a pressure-sensitive thermosensitive coloring layer 46P formed on T '.
Further, in the modified embodiment of FIG. 14, in the thermosensitive coloring layer 46T '.
The side contains a black leuco dye component “△”, and the pressure-sensitive and heat-sensitive coloring layer 46P ′ side contains a leuco dye component for emerald green coloring “○”. However, the color development characteristics of the three colors (magenta, emerald green, and black) of the multicolor recording medium 40 'according to this modified embodiment are almost the same as those shown in the graph of FIG.

In each of the first embodiment shown in FIG. 1, the second embodiment shown in FIG. 12, and the modified embodiment shown in FIG. 14, the color-forming layers 14, 44 and 44 'have a two-layer structure. However, each color forming layer (14, 44, 4
4 ') may have a single-layer structure. For example, when the coloring layer 14 has a single-layer structure in the second embodiment, the composition liquid C and the composition liquid D described above may be mixed at a ratio of 1: 1 and applied to the thermal transfer paper 42. The amount of application is about 5 to 7 per square meter.
It can be on the order of grams.

In the case of performing black coloring, it is also possible to form the coloring layer as a three-layer structure. In this case, for example, a modification of the second embodiment shown in FIG. The black thermosensitive coloring layer 46T ′ of the embodiment, the emerald green thermosensitive coloring layer 46T of the second embodiment shown in FIG. 12, and the pressure-sensitive thermosensitive magenta coloring layer 16P of the first embodiment shown in FIG. About 2 to 4 grams per application may be applied. By adopting such a three-layer structure, mixing of other colors into each color development, so-called fog, can be effectively reduced.

In the above-described embodiment, the color material based on the leuco dye is encapsulated in the pressure-sensitive microcapsules (18, 48). However, the leuco dye itself is encapsulated in the pressure-sensitive microcapsule as a solid. However, in that case, the color development temperature of the leuco dye can be adjusted as needed by adding a sensitizer or the like.

In addition, pressure-sensitive microcapsules (18, 4
8) It is also possible to make the color material in a molten state at room temperature and to immediately develop color when it is destroyed. In this case, it is possible to easily control the color mixture (color tone) of each color and the heat generation of the printer. Will be. That is, the temperature coloring property of the leuco dye is determined by the eutectic point of the developer and the sensitizer. However, if the leuco dye can be colored at room temperature, the choice of the leuco dye is arbitrary regardless of its melting point. Can be done.

Further, heat-sensitive microcapsules (18, 4
It is not always necessary to use a leuco dye for the coloring material to be encapsulated in 8), and it is possible to use various colored dyes and pigments, but in that case, the wall film of the pressure-sensitive microcapsule may be used. Need to be whitened. In this case, the pressure-sensitive thermosensitive coloring layer can be formed with a binder material such as wax having an appropriate heat melting temperature instead of the developer and sensitizer components contained therein.

Various embodiments of the multicolor recording medium according to the present invention include a pressure-sensitive and heat-sensitive coloring layer (16P, 46P, 46P ') formed on a suitable support (12, 42, 42). The medium can be realized by a medium, and such a pressure-sensitive and heat-sensitive coloring medium also constitutes one of the main features of the present invention.

[0103]

As is clear from the above description, the present invention is not only capable of producing a color by mixing two basic colors but also capable of independently producing each of the basic colors. The multi-color recording medium according to the present invention is more excellent in terms of color-forming function and efficiency than the conventional additive-type multi-color thermal paper. Further, according to the present invention, by using the pressure-sensitive microcapsules, it is possible to arbitrarily select at least one of the basic colors without being restricted by a coloring temperature or the like. Furthermore, in the multicolor recording medium according to the present invention, the color development temperature of the coloring material enclosed therein by using pressure-sensitive microcapsules is set to 100 ° C.
In the following, erroneous coloring caused by careless heating can be prevented, so that the overall printing energy can be reduced.

[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 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. 3 is a control block diagram of a thermal head included in the image recording apparatus of FIG.

FIG. 4 is a schematic cross-sectional view schematically showing a state in which a heating element of a thermal head of the printing apparatus shown in FIG. 3 causes a coloring layer of the multi-color recording medium of FIG.

FIG. 5 is a graph showing color development characteristics of the multicolor recording medium shown in FIG.

FIG. 6 is a graph showing the coloring characteristics when the thickness of the coloring layer of the multicolor recording medium shown in FIG. 1 is changed.

FIG. 7 is a graph showing color development characteristics when a filler in a color development layer is added to the multicolor recording medium shown in FIG.

8 is a graph showing color development characteristics when the average particle size of the pressure-sensitive microcapsules is changed in the multicolor recording medium shown in FIG.

9 is a graph showing color development characteristics when the material of a support is changed in the multicolor recording medium shown in FIG.

10 is a graph showing color development characteristics when the pressure-resistant strength of the pressure-sensitive microcapsule is changed in the multicolor recording medium shown in FIG.

11 is a graph showing color development characteristics when the surface roughness of a support of the multicolor recording medium shown in FIG. 1 is changed.

FIG. 12 is a schematic sectional view schematically showing a part of a second embodiment of the multicolor recording medium according to the present invention.

FIG. 13 is a graph showing color development characteristics of the multi-color recording medium shown in FIG.

FIG. 14 is a schematic sectional view schematically showing a part of a modified embodiment of the second embodiment shown in FIG. 12;

[Description of Signs] 10 Multicolor recording medium 12 Support (sheet) 14 Coloring layer 16P Pressure-sensitive thermosensitive coloring layer 16T Thermosensitive coloring layer 18 Pressure-sensitive microcapsule

Claims (18)

[Claims] 1. A multicolor recording medium comprising a support and a color-forming layer formed on the surface of the support, wherein the color-forming layer encloses at least one thermosensitive color-forming component and a color material having a desired hue. And a plurality of pressure-sensitive microcapsules uniformly distributed, wherein the pressure-sensitive microcapsules are broken under a predetermined pressure and within a first temperature range so as to develop a color temperature. Color-forming properties are provided, wherein the thermosensitive color-forming component has a second temperature between a first temperature included in the first temperature range and a second temperature exceeding an upper limit temperature of the first temperature range. A multi-color recording medium, which is provided with a temperature color developing characteristic in which a color is developed in a hue different from the color material within the range. 2. The multi-color recording medium according to claim 1, wherein a color formed by said color material and a color formed by said thermosensitive color component are formed between said first temperature and an upper limit temperature of said first temperature range. A multi-color recording medium capable of obtaining mixed colors. 3. The multi-color recording medium according to claim 1, wherein only the coloring by the thermosensitive coloring component is obtained between the upper limit temperature of the first temperature range and the second temperature. Multi-color recording medium. 4. The multi-color recording medium according to claim 1, wherein the setting of the first temperature range includes setting a layer thickness of the coloring layer, a filler content in the coloring layer, The process is performed by changing at least one parameter selected from the group consisting of an average particle diameter of the pressure-sensitive microcapsules, a pressure-resistant strength of the pressure-sensitive microcapsules, a material of the support, and a surface roughness of the support. A multi-color recording medium characterized by the above-mentioned. 5. The multi-color recording medium according to claim 1, wherein a lower limit temperature of said first temperature range is set to 100 ° C. or lower. Medium. 6. The multi-color recording medium according to claim 1, wherein the coloring layer further contains another thermosensitive coloring component in addition to the thermosensitive coloring component. Wherein the heat-sensitive coloring component is provided with a temperature coloring property that develops a color different from the two hues in a third temperature range equal to or higher than the second temperature. . 7. The multi-color recording medium according to claim 6, wherein said two thermosensitive coloring components comprise a leuco dye, and said color-forming layer contains a developer component of said leuco dye. Multi-color recording medium. 8. The multi-color recording medium according to claim 7, wherein the first temperature is a color development start temperature of a leuco dye having a thermosensitive color development characteristic defined by the second temperature range. Wherein the temperature is the color development start temperature of a leuco dye having a thermosensitive color development characteristic defined by the third temperature range. 9. The multi-color recording medium according to claim 7, wherein the leuco dye having a thermosensitive coloring property defined by the third temperature range is a leuco dye for black coloring. Medium. 10. The multi-color recording medium according to claim 7, wherein the color material encapsulated in the pressure-sensitive microcapsules is a color material based on a leuco dye, and A multicolor recording medium wherein the colorant undergoes thermal melting at a lower limit temperature of the first temperature range. 11. The multi-color recording medium according to claim 1, wherein said color-forming layer comprises a pressure-sensitive thermosensitive coloring layer containing said pressure-sensitive microcapsules and a thermosensitive coloring layer containing said thermosensitive coloring component. A multi-color recording medium having a structure. 12. The multicolor recording medium according to claim 11, wherein the color material encapsulated in the pressure-sensitive microcapsules is a color material based on a leuco dye, and the pressure-sensitive thermosensitive coloring layer includes a leuco dye. A multicolor recording medium, comprising a developer component of a dye, wherein the developer component undergoes thermal melting at a lower limit temperature of the first temperature range. 13. The multicolor recording medium according to claim 11, wherein the pressure-sensitive thermosensitive coloring layer contains another thermosensitive coloring component different from the thermosensitive coloring component contained in the thermosensitive coloring layer. The other heat-sensitive coloring component is provided with a temperature coloring characteristic that is colored in a hue different from the two hues in a third temperature range equal to or higher than the second temperature. Multi-color recording medium. 14. The multi-color recording medium according to claim 13, wherein the two thermosensitive coloring components comprise a leuco dye, and the pressure-sensitive thermosensitive coloring layer and the thermosensitive coloring layer each include a color developed by the leuco dye. A multi-color recording medium characterized by containing an agent component. 15. The multicolor recording medium according to claim 13, wherein the first temperature is a color development start temperature of the leuco dye contained in the thermosensitive coloring layer, and
Wherein the temperature is the color development start temperature of the leuco dye contained in the pressure-sensitive and heat-sensitive coloring layer. 16. The multicolor recording medium according to claim 14, wherein the leuco dye contained in the pressure-sensitive and heat-sensitive coloring layer is a leuco dye for black coloring. 17. A pressure-sensitive thermosensitive coloring medium comprising a support and a pressure-sensitive thermosensitive coloring layer formed on the support, wherein the pressure-sensitive thermosensitive coloring layer comprises a plurality of pressure-sensitive microcapsules in a binder material. Formed as evenly distributed,
A color material having a desired hue is encapsulated in the pressure-sensitive microcapsule, and the pressure-sensitive microcapsule is broken down under a predetermined pressure and within a predetermined temperature range to develop a pressure-temperature coloring characteristic. Is given, the setting of the temperature range is the thickness of the pressure-sensitive thermosensitive coloring layer, the filler content in the pressure-sensitive thermosensitive coloring layer, the average particle size of the pressure-sensitive microcapsules,
A pressure-sensitive thermosensitive coloring medium, which is performed by changing at least one parameter selected from a group consisting of a pressure resistance of the pressure-sensitive microcapsules, a material of the support, and a surface roughness of the support. 18. The pressure-sensitive thermosensitive coloring medium according to claim 17, wherein the coloring material encapsulated in the pressure-sensitive microcapsules is a coloring material based on a leuco dye, and the binder material is a coloring material of the coloring material. A pressure-sensitive and heat-sensitive coloring medium, comprising a colorant, wherein the developer undergoes thermal melting at a lower limit of the temperature range.