JP2001162944A - Heat sensitive microcapsule and recording medium utilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide novel heat sensitive microcapsules, which are stable against the exposure of light and consequently easy in handling and a heat sensitive recording medium utilizing the microcapsules, at the use of which no waste develops substantially and which is not only easy in handling but also can easily record a monochromatic image at low cost. SOLUTION: This heat sensitive recording medium 2 consists of a sheet of paper 4 and a microcapsule layer 6 coated on the surface of the sheet. The microcapsule layer is made of heat sensitive microcapsules 8, each of which consists of liquid coloring material having predetermined boiling point and a wall film, in which the liquid coloring material is sealed. The wall film has temperature destruction characteristics so that the film is broken by itself due to the rise of its inner pressure under the state heated beyond the boiling point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule enclosing a coloring material, and a recording medium using the microcapsule.

[0002]

2. Description of the Related Art Conventionally, a recording medium having a microcapsule layer formed by applying a microcapsule enclosing a colorant to a suitable support, for example, a sheet of paper, is well known. A recording medium using a photocurable resin for a wall film of a capsule is known. Exposure is performed on the microcapsule layer of the recording medium according to the recording image pattern, and thereafter, a predetermined pressure is applied to the recording medium. During such a pressing process, the unexposed or uncured microcapsules are destroyed,
However, the exposed microcapsules, that is, the cured microcapsules are not destroyed, and an image corresponding to the exposure of the image pattern to be recorded is recorded on the microcapsule layer of the recording sheet.

On the other hand, as another example of a recording medium having a microcapsule layer, a dye containing a diazo compound is sealed in microcapsules in the microcapsule layer, and the microcapsules are selectively heated to a specific temperature. There is also known a recording sheet which causes the coloring of the dye. A dye containing a diazo compound, which is colored on the microcapsule layer of such a recording medium, is fixed by irradiation with light of a specific wavelength such as ultraviolet light.

[0004]

The manufacturing process of the former recording medium must be performed in a light-shielding environment in which the microcapsules are not subjected to light curing. Must be kept in a state,
Moreover, image recording on this type of recording medium must be performed in a light-shielded environment. Of course, such a limitation is that when the microcapsule layer of the recording medium is exposed to light, the wall film of the microcapsule is hardened. Also,
Unexposed microcapsules (that is, uncured microcapsules) are easily broken, and care must be taken in handling the recording medium so that careless external force is not applied thereto. As described above, the former recording medium must be stored in a light-shielding package or the like at the time of storage, and therefore, there is a problem that the cost per recording medium is increased and the entire apparatus becomes larger. Further, there is a problem that after using the recording medium, the light-shielding package or the like must be treated as waste.

Further, in the latter recording medium, light irradiating means is required for fixing the coloring pigment, so that the light irradiating means is indispensable for the image recording apparatus of the latter recording medium. . For this reason, the latter recording medium has a problem that not only the size of the image recording apparatus is increased but also the power consumption is increased. Furthermore, when a color image is recorded on the latter recording medium, it is necessary to repeat heating / irradiation for each color, which causes another problem that a color image cannot be formed quickly.

Furthermore, in both the former and latter recording media, the control parameters include the use of light, and the exposure of the recording medium itself due to exposure to sunlight outdoors or long-term exposure indoors. There is also the problem that control characteristics can be lost.

Accordingly, a first object of the present invention is to provide a novel heat-sensitive microcapsule that is stable and easy to handle against exposure to light.

[0008] A second object of the present invention is a heat-sensitive recording medium configured to form a single-color image using the above-mentioned heat-sensitive microcapsules. It is an object of the present invention to provide a novel heat-sensitive recording medium which is not only easy to handle but also can easily record a monochrome image at low cost.

A third object of the present invention is a pressure-sensitive heat-sensitive recording medium configured to form a color image of two or more colors by using the above-mentioned heat-sensitive microcapsules. It is an object of the present invention to provide a novel pressure-sensitive heat-sensitive recording medium which does not substantially involve waste when used, is easy to handle, and can record a color image at low cost and easily.

[0010]

According to a first aspect of the present invention, there is provided a heat-sensitive microcapsule. The heat-sensitive microcapsule encloses a liquid coloring material having a predetermined boiling point and the liquid coloring material. And a wall membrane. Such a heat-sensitive microcapsule is characterized in that the wall film has a temperature destruction property such that the wall film is destroyed by the rise of its internal pressure under a heating condition of a boiling point or higher and releases the liquid color material.

Preferably, the liquid colorant is a liquid vehicle,
And a pigment dispersed or dissolved in the liquid vehicle. As the liquid vehicle, a transparent oil, particularly a transparent oil having a high boiling point, can be used. Such a clear oil may consist of at least two oil components having different boiling points to obtain a desired boiling point. on the other hand,
The wall film of the heat-sensitive microcapsule may be formed from a thermosetting resin, or may be formed from a high melting point thermoplastic resin.

According to a second aspect of the present invention, there is provided a heat-sensitive recording medium using the above-described heat-sensitive microcapsules, and the heat-sensitive recording medium is coated on a support and a surface of the support. And a microcapsule layer. Of course,
Such a thermosensitive recording medium is characterized in that the microcapsule layer is formed from the thermosensitive microcapsules as described above. That is, the heat-sensitive microcapsules are composed of a liquid coloring material having a predetermined boiling point, and a wall film enclosing the liquid coloring material, and the wall film is destroyed by its internal pressure rise under a heating state above the boiling point. And has a temperature destruction characteristic that releases the liquid color material.

According to a third aspect of the present invention, there is provided a pressure-sensitive heat-sensitive recording medium using the above-described heat-sensitive microcapsules, the pressure-sensitive heat-sensitive recording medium comprising a support, and a surface of the support. And a microcapsule layer applied to the substrate. The microcapsule layer is composed of first, second and third microcapsule layer portions, where the third microcapsule layer portion is first formed on the surface of the support, and then the second microcapsule layer portion is formed. A third microcapsule layer portion is formed, followed by a first microcapsule layer portion formed on a second microcapsule layer portion. The first microcapsule layer portion is composed of a plurality of first microcapsules uniformly distributed in a first binder material, and each of the first microcapsules is filled with a first coloring material. . The second microcapsule layer portion comprises a number of second microcapsules uniformly distributed in a second binder material, each of which encapsulates a second colorant. . The third microcapsule layer portion comprises a number of third and fourth microcapsules evenly distributed in a third binder material, each of which has a third colorant. The fourth microcapsule is sealed with a fourth coloring material. In such a pressure-sensitive heat-sensitive recording medium, the first binder material has a first heat melting temperature, and the first microcapsules in the first microcapsule layer portion are thermally softened of the first binder material. A second binder material having a second heat melting temperature higher than the first heat melting temperature, the second binder material having a pressure rupture property that is broken under a first pressure in a state or a heat melting state; The second microcapsule in the microcapsule layer portion has a pressure rupture property in which the second microcapsule is ruptured under a second pressure lower than the first pressure in a heat softened state or a hot melt state of the second binder material. And the third binder material has a third heat melting temperature higher than the second heat melting temperature, and the third microcapsules in the third microcapsule layer portion are thermally softened of the third binder material. Pressure in a state or hot melt The fourth colorant has a higher boiling point than the third heat melting temperature of the third binder material, and the fourth microcapsule has It is characterized in that it has a temperature destruction characteristic such that it is destroyed by itself at least under the heating state of the boiling point of the fourth color material and releases the fourth color material. In short, in the pressure-sensitive thermosensitive recording medium according to the third aspect of the present invention, the fourth microcapsule is configured as a heat-sensitive microcapsule as described above.

In the pressure-sensitive thermosensitive recording medium according to the third aspect of the present invention, preferably, the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules. Is smaller than the third average particle size. Preferably, first spacer particles larger than the average particle diameter of the first microcapsules are uniformly distributed in the first microcapsule layer portion, and the second spacer particles are formed in the second microcapsule layer portion. The second spacer particles larger than the average particle size of the microcapsules are evenly distributed. The first and second spacer particles may be formed from an inorganic material, or may be formed from a high melting point synthetic resin material.

In the pressure-sensitive and heat-sensitive recording medium according to the third aspect of the present invention, preferably, the first, second and third recording media are used.
Are formed as binder particles fused to each other, and each of the first, second, and third microcapsule layer portions is formed as a stone wall structure.

Further, in the pressure-sensitive thermosensitive recording medium according to the third aspect of the present invention, each of the first, second and third coloring materials is composed of a vehicle and a dye dispersed or dissolved in the vehicle. Can be. Preferably, a leuco dye is used as the pigment, in which case the first, second and third binder materials each include a leuco dye developer. For the first, second and third color materials, for example, three primary colors consisting of cyan, magenta and yellow may be constituted,
In this case, the fourth color material is black. Preferably, the average particle size of the fourth microcapsules configured as the heat-sensitive microcapsules as described above is smaller than the average particle size of the first, second, and third microcapsules.

According to a fourth aspect of the present invention, there is provided a pressure-sensitive thermosensitive recording medium using the heat-sensitive microcapsules as described above. The pressure-sensitive thermosensitive recording medium also includes a support and a surface of the support. And a microcapsule layer applied to the substrate. The microcapsule layer is composed of first and second microcapsule layer portions, where the second microcapsule layer portion is first formed on the surface of the support, and then the first microcapsule layer portion is formed of the second microcapsule layer portion. It is formed on the microcapsule layer portion. The first microcapsule layer portion is composed of a plurality of first microcapsules uniformly distributed in a first binder material, each of the first microcapsules being encapsulated with a first colorant, The second microcapsule layer portion comprises a number of second and third microcapsules evenly distributed in a second binder material, each of the second microcapsules having a second colorant. And a third coloring material is sealed in each of the third microcapsules. In such a pressure-sensitive thermosensitive recording medium, the first binder material has a first heat melting temperature, and the first microcapsules in the first microcapsule layer portion are in a state of thermal softening of the first binder material. A second binder material having a second heat melting temperature higher than the first heat melting temperature, the second binder material having a pressure rupture property to be broken under a first pressure in a heat melting state; The second microcapsules in the microcapsule layer portion have a pressure rupture property in which the second microcapsules are ruptured under a second pressure lower than the first pressure in a heat-softened state or a heat-melted state of the second binder material. The third colorant encapsulated in each of the third microcapsules has a boiling point higher than the second heat melting temperature of the second binder material, and the third microcapsules have at least the third color. Destroyed by itself under the heating condition of the boiling point of the material It is characterized to have a temperature fracture characteristics became cormorants. In short, in the pressure-sensitive thermosensitive recording medium according to the fourth aspect of the present invention, the third microcapsule is configured as a heat-sensitive microcapsule as described above.

In the pressure-sensitive thermosensitive recording medium according to the fourth aspect of the present invention, the average particle size of the first microcapsules is preferably smaller than the average particle size of the second microcapsules. Is smaller than the first and second average particle sizes. Also, preferably,
Spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the first microcapsule layer portion, and the space particles can also be formed from an inorganic material or a high melting point synthetic resin material.

In the pressure-sensitive and heat-sensitive recording medium according to the fourth aspect of the present invention, each of the first and second binder materials may be formed as binder particles fused to each other. The second microcapsule layer portion is formed as a stone wall structure.

Further, in the pressure-sensitive thermosensitive recording medium according to the fourth aspect of the present invention, each of the first, second and third coloring materials is composed of a vehicle and a dye dispersed or dissolved in the vehicle. It can be. Preferably, a leuco dye is used as the pigment, in which case the first, second and third binder materials each include a leuco dye developer. The first, second and third color materials constitute, for example, three primary colors of cyan, magenta and yellow. Preferably, the average particle size of the third microcapsules configured as the heat-sensitive microcapsules as described above is smaller than the average particle size of the first and second microcapsules.

According to a fifth aspect of the present invention, there is provided a pressure-sensitive thermosensitive recording medium using the heat-sensitive microcapsules as described above. The pressure-sensitive thermosensitive recording medium comprises a support, and a surface of the support. And a single microcapsule layer applied to the Such a single microcapsule layer comprises a number of first and second microcapsules uniformly distributed in a binder material, each of the first microcapsules having a first colorant encapsulated therein. A second coloring material is sealed in each of the second microcapsules. In such a pressure-sensitive thermosensitive recording medium, the binder material has a predetermined heat melting temperature, and the first microcapsules are in a heat-softened state or a heat-melted state of the binder material and higher than the heat-melting temperature of the binder material. The second colorant encapsulated in each of the second microcapsules has a boiling point higher than the first temperature, having a pressure rupture property that is broken under a first pressure at a first temperature. , The second microcapsule is at least the second
It is characterized in that it has a temperature-destructive property such that it is destroyed by itself under the heating condition of the boiling point of the coloring material. In short, in the pressure-sensitive thermosensitive recording medium according to the fifth aspect of the present invention, the second microcapsules are configured as the heat-sensitive microcapsules as described above.

In the pressure-sensitive thermosensitive recording medium according to the fifth aspect of the present invention, preferably, the average particle size of the second microcapsules is smaller than the average particle size of the first microcapsules. Preferably, spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the microcapsule layer, and the spacer particles can also be formed from an inorganic material or a high melting point synthetic resin material.

Also in the pressure-sensitive thermosensitive recording medium according to the fifth aspect of the present invention, preferably, the binder material is formed as binder particles fused to each other, and at this time, the microcapsule layer is formed as a stone wall structure. .

Further, in the pressure-sensitive and heat-sensitive recording medium according to the fifth aspect of the present invention, each of the first and second coloring materials can be composed of a vehicle and a dye dispersed or dissolved in the vehicle. Preferably, a leuco dye is used as a pigment, and a developer of the leuco dye is contained in the binder material. Preferably, the average particle size of the second microcapsules configured as the heat-sensitive microcapsules as described above is smaller than the average particle size of the first microcapsules.

According to a sixth aspect of the present invention, there is provided a pressure-sensitive thermosensitive recording medium using the above-described heat-sensitive microcapsules. The pressure-sensitive thermosensitive recording medium also includes a support and a surface of the support. A single microcapsule layer applied to the Such a single microcapsule layer comprises a number of first, second and third microcapsules uniformly distributed in a binder material, each of the first microcapsules having a first colorant. , A second coloring material is sealed in each of the second microcapsules, and a third coloring material is sealed in each of the third microcapsules.
In such a pressure-sensitive thermosensitive recording medium, the binder material has a predetermined heat melting temperature, and the first microcapsules are in a heat-softened state or a heat-melted state of the binder material and higher than the heat-melting temperature of the binder material. The first under the first temperature
Wherein the second microcapsules have a pressure-rupture property to be broken under pressure, and the second microcapsules are in a heat-softened state or a heat-melted state of the binder material and at a second temperature higher than the first temperature. A third colorant encapsulated in each of the third microcapsules has a boiling point higher than the second temperature, the pressure material having a pressure rupture property that is broken under a second pressure lower than the pressure;
The third microcapsules are characterized in that they have a temperature destruction property such that the third microcapsules are destroyed by themselves at least under the heating state of the boiling point of the third colorant. In short, in the pressure-sensitive thermosensitive recording medium according to the sixth aspect of the present invention, the third microcapsule is configured as a heat-sensitive microcapsule as described above.

In the pressure-sensitive thermosensitive recording medium according to the sixth aspect of the present invention, preferably, the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules, Is smaller than the first and second average particle sizes. Preferably, the second microcapsule has a double wall structure, and one of the inner wall film and the outer wall film has the second microcapsule described above.
Is given such a property as to melt or soften at a temperature of. Further, it is preferable that spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the single microcapsule layer, and the spacer particles can also be formed of an inorganic material or a high melting point synthetic resin material.

Also, in the pressure-sensitive thermosensitive recording medium according to the sixth aspect of the present invention, preferably, the binder material is formed as binder particles fused to each other, and at this time, the microcapsule layer is formed as a stone wall structure. .

Further, in the pressure-sensitive thermosensitive recording medium according to the sixth aspect of the present invention, each of the first, second and third coloring materials is a vehicle and a dye dispersed or dissolved in the vehicle. It can consist of Preferably, a leuco dye is used as a pigment, and a developer of the leuco dye is contained in the binder material. The first, second, and third color materials are, for example, cyan, magenta, and yellow.
Of the three primary colors.

[0029]

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

Referring first to FIG. 1, as a first embodiment of a recording medium according to the present invention, a thermosensitive recording medium 2 is shown, which comprises a suitable support such as a sheet of paper 4 and a sheet of paper. And a microcapsule layer 6 applied to one surface of the paper. A large number of heat-sensitive microcapsules 8 are evenly distributed in the microcapsule layer 6, and all the heat-sensitive microcapsules 8 are filled with a liquid color material of the same color, for example, black. Each heat-sensitive microcapsule 8 is heated to a predetermined temperature. When destroyed, it is configured to break down itself and emit a liquid black colorant therefrom.

More specifically, the wall film of the microcapsule 8 is formed of a suitable resin material colored in the same color (usually white) as the sheet paper 4, for example, a high melting point thermoplastic resin or a thermosetting resin. The black colorant encapsulated in is a suitable transparent oil mixed with about 10% (weight percent) of a black dye. As the transparent oil, KMC-113 manufactured by Kureha Chemical Co., Ltd., that is, 2,7 diisopropyl naphthalene (boiling point: about 300 ° C.) is added with n-heptane at a ratio of 10% to have a primary azeotropic point of about 190 ° C., for example. The carbon black or the like is used as the black pigment. For the microcapsules 8, a known microcapsule manufacturing method, for example,
It can be produced by an interfacial polymerization method or an in situ polymerization method as disclosed in JP-A-3492 and JP-A-58-82785, and has an average particle size of about 1 μm to about 3 μm. The thickness of the wall film is determined by the boiling point of the black coloring
When heated to a temperature of 190 ° C.) or more, it is easily broken by the increase of its internal pressure, so that the black color material can be released.

In order to obtain a desired boiling point for the black colorant oil, other boiling point adjusting substances such as xylene, benzene or naphthalene having a boiling point lower than that of KMC-113 may be used in place of n-heptane. Thus, a desired breaking temperature can be set for the microcapsules 8 in this manner. Although the microcapsules 8 have relatively high strength against an external pressure, they can be relatively easily broken against an internal pressure generated at a heating temperature exceeding the boiling point of the oil of the black coloring material.

With respect to the formation of the microcapsule layer 6,
A 3% aqueous solution of a suitable binder material, for example, polyvinyl alcohol (degree of polymerization 2,000) is prepared. For 100 g of this aqueous solution of polyvinyl alcohol, for example, 10 g of heat-sensitive microcapsules 8 and a small amount of a dispersant (todecylbenzenesulfonic acid) Sodium)) to prepare the suspension and then spray and dry the suspension on sheet paper 4 at about 5 grams per square meter.

In FIG. 1, the microcapsule layer 6 is schematically shown as a state in which individual microcapsules 8 are arranged one by one on the surface of the sheet paper 4 (ie, the microcapsule layer 6). Although the layer thickness of the microcapsules is shown to be approximately equal to the diameter of each microcapsule 8), in practice, a plurality of microcapsules overlap each other in the thickness direction of the microcapsule layer 6, and The layer thickness itself is larger than the diameter of the microcapsule 8.

The heat-sensitive recording medium 2 obtained as described above
Can record a monochrome image on the microcapsule layer 6 using a conventional thermal printer. In this case, the respective heating elements of the thermal head of the thermal printer can be heated to a temperature equal to or higher than the primary azeotropic point (190 ° C.) of the black color material, for example, 210 ° C., when energized. By selectively controlling the energization, black dots are colored on the microcapsule layer 6 to form a monochromatic image. In short, when a temperature of 210 ° C. is applied on the microcapsule layer 6 by each heating element, the black color material of the microcapsules 8 included in the temperature application region is heated to a temperature higher than its primary azeotropic point, and thus the microcapsules are heated. The internal pressure in 8 rises sharply, the black coloring material breaks through the wall film and is released, and black dots are colored on the microcapsules. The dot size obtained by each heating element of the conventional thermal head is about 50 μm to about
100 μm.

If the wall film of the microcapsule 8 is formed of a material that does not exhibit sufficient adhesiveness to polyvinyl alcohol as a binder material, for example, an amino resin, a wax powder more suitable for the above suspension is used. Is mixed with an appropriate amount, for example, 10 grams, and the suspension
After spraying about 5 grams per square meter and drying, the wax powder is heated to a temperature close to the hot melting temperature of the wax powder to partially or entirely heat soften or melt the wax powder to microcapsules 8 to microcapsules. It may be fixed in the layer 6. For example, if the heating temperature is maintained at a temperature somewhat lower than the heat melting temperature of the wax powder, the wax particles of the wax powder are heat fused to each other to obtain a stone wall structure by the wax particles, in which case the microcapsules 8 will be distributed in the stone wall structure. On the other hand, if the heating temperature is equal to or higher than the heat melting temperature of the wax powder, the wax powder is completely melted by heat, and in this case, the microcapsules 8 are distributed in the solid wax binder layer. The wax powder is of course colored the same color as the sheet paper 4 (usually white).

When the microcapsule layer 6 is formed using wax powder, the heat melting temperature of the wax powder is set to a temperature not higher than the primary azeotropic point of 190 ° C. of the black coloring material. As such a wax powder, for example, PPW-5 (polypropylene, wax,
Powder) and CWP-3 (microcrystalline wax powder) can be used, and these wax powders are also preferable from the viewpoint of heat conduction efficiency. The average particle size of PPW-5 is 3 to 5 μm, its heat melting temperature is about 150 ° C, and the average particle size of CWP-3 is 3 μm.
And its heat melting temperature is about 108 ° C.

In the above-described first embodiment, carbon black is used as a black pigment, but a leuco dye which develops black by a chemical reaction with a color developer may be used. As is well known,
The leuco dye itself is usually milky or translucent, and such a leuco dye emits a predetermined color by a chemical reaction with a developer. As the leuco dye for black coloring, for example, BlacK 15 manufactured by Yamamoto Kasei Co., Ltd. can be used. Of course, when a leuco dye is used, for example, a colorless zinc salicylate or activated clay is mixed as a color developer into the microcapsule layer 6, whereby a black color material (leuco dye) is produced from the microcapsule 6. When released, black will be developed by a chemical reaction with the color developer.

In the above-described first embodiment, various additives are added to the microcapsule layer 6 to improve the reliability of the thermal recording medium 2 and to improve the image quality of an image to be recorded thereon. Can be added. For example,
Examples of such additives include an adhesion inhibitor for preventing the emission color material and the molten wax from adhering to the heating element of the thermal head, a fixing agent (so-called filler) for quickly adsorbing and fixing the emission color material, and recording. Examples thereof include an ultraviolet ray inhibitor and an antioxidant for preventing fading of an image.

Referring to FIG. 2, as a second embodiment of the recording medium according to the present invention, a pressure-sensitive thermosensitive recording medium 10 is shown, which comprises a suitable support such as a sheet of paper 12; A microcapsule layer 14 applied to one surface of the sheet paper 12. In the present embodiment, the microcapsule layer 14 has a three-layer structure for recording a full-color image thereon. That is, the microcapsule layer 14 selectively includes a first microcapsule layer portion 16C for recording a cyan image, a second microcapsule layer portion 16M for recording a magenta image, and a yellow image and a black image. A third microcapsule layer portion 16Y / B for recording, wherein the third microcapsule layer portion 16Y / B is first formed on the surface of the sheet paper 12, and then the second microcapsule layer portion 16M is formed. Third microcapsule layer portion 16Y
/ B, and then the first microcapsule layer portion 16C is formed on the second microcapsule layer portion 16M.

As schematically shown in FIGS. 2 and 3, the third
The microcapsule layer portion 16Y / B has a stone wall structure, in which a number of microcapsules 18Y encapsulating a yellow color material and a number of microcapsules 18BK encapsulating a black color material include wax type binder particles 20.
Distributed evenly throughout.

The wall film of the microcapsule 18Y is formed of an amino resin (thermosetting resin) colored in the same color (usually white) as the sheet paper 12, and the yellow color material enclosed therein is made of a suitable transparent oil. About 10% (weight percent) of a yellow dye. In the present embodiment, 2,7 diisopropylnaphthalene (boiling point: about 300 ° C.) is used as the transparent oil, and this transparent oil is available as KMC-113 manufactured by Kureha Chemical Company. Benzine yellow-G or the like is used as the yellow dye. Such a microcapsule 18Y can also be manufactured by the conventional microcapsule manufacturing method as described above, and has an average particle size of about 9 μm to about 10 μm.
The thickness of the wall film is such that the microcapsules 18Y can be broken under a pressure of 0.02 MPa or more accompanied by a shearing force.

The microcapsules 18BK correspond to the first
It is of substantially the same type as the heat-sensitive microcapsules 8 used in the embodiment. That is, microcapsule 1
The 8BK wall film is formed of a suitable resin material, for example, an amino resin, which is colored in the same color (usually white) as the sheet paper 12, and the black color material enclosed therein is approximately 10% (weight by weight) in a suitable transparent oil. %) Of a black dye. As a transparent oil, KMC- manufactured by Kureha Chemical Co., Ltd.
113, that is, 2,7 diisopropyl naphthalene (boiling point of about
(300 ° C.) and n-heptane added at a ratio of 10% to prepare a primary azeotropic point of about 190 ° C., and carbon black or the like is used as a black pigment. Such microcapsules 18BK can also be manufactured by the conventional microcapsule manufacturing method as described above, and the average particle size thereof is about 1 μm.
m to about 3 μm, and the thickness of the wall film is such that the microcapsules 18BK can withstand a pressure of 3.0 MPa or more at a temperature lower than the primary azeotropic point (about 190 ° C.) of the black coloring material. However, when heated to a temperature equal to or higher than the primary azeotropic point of the black coloring material enclosed therein, the black coloring material breaks down the wall film of the microcapsule 18BK due to an increase in its internal pressure and is released. It is to be gained. As described above, in order to obtain a desired boiling point, KMC-113 was used instead of n-heptane.
Xylene, benzene, naphthalene, or the like having a lower boiling point can also be used.

On the other hand, the wax type binder particles 20
Polypropylene wax is used. Such binder particles 20 are available as PPW-5 (polypropylene wax powder) manufactured by Seishin Enterprise Co., Ltd., and have an average particle size of about 3 to 5 μm. And its hot melting temperature is about 150 ° C. The binder particles 2
0, that is, the polypropylene wax powder is white.

Third microcapsule layer portion 16Y / B
Can be obtained by the following method. (1) Prepare a 3% aqueous solution of polyvinyl alcohol (degree of polymerization 2,000), and add 10 grams of PPW-5 (polypropylene wax powder) to 100 grams of this adhesive aqueous solution.
And an appropriate amount, for example, 10 grams of microcapsules 18Y
And an appropriate amount, for example, 10 grams of microcapsules 18B
K and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) are mixed / stirred to prepare a suspension. ■ The above suspension is sprayed onto sheet paper 12 in an amount of about 5 grams per square meter and air-dried once, and then placed in a heating oven to obtain a heat melting temperature of PPW-5 (approx.
(145 ° C.), which is slightly lower than 150 ° C., and is maintained for about 15 minutes.
(Polypropylene wax powder), that is, the binder particles 20 are thermally fused to each other, thus obtaining a stone wall structure as shown in FIG. In addition, such a heat treatment is a treatment for increasing the strength of the stone wall structure, and if the strength of the stone wall structure is sufficient with the adhesive strength obtained with a polyvinyl alcohol aqueous solution or another adhesive aqueous solution,
Such a heat treatment can be omitted.

According to the method described above, since the binder particles 20 themselves are not melted by heat, a minute gap is left between the binder particles and the microcapsules 18Y, and the microcapsules 18Y and the microcapsules 18Y are not melted. Since the specific gravity of the capsule 18BK is greater than the specific gravity of the binder particles 20, the microcapsules 18Y and 18BK sink below the third microcapsule layer portion 16Y / B and are covered by the binder particles 20. .

Third microcapsule layer portion 16Y / B
In the above, when the binder particles 20 are in a solid phase state, that is, when the heating temperature for the third microcapsule layer portion 16Y / B is 150 ° C.
In the following case, even if a breaking pressure of 0.02 MPa or more accompanied by shearing force is applied to the third microcapsule layer portion 16Y / B, the breaking pressure is blocked by the stone wall structure of the binder particles 20 and the It does not extend directly to the capsules 18Y and 18BK, so that the microcapsules 18Y and 18BK are not destroyed.

However, when the heating temperature for the third microcapsule layer portion 16Y / B is 150 ° C. or more of the heat melting temperature of the binder particles 20 and the primary azeotropic point of the black color material of the microcapsules 18BK is about 190 ° C. or less. ,
Since the binder particles 20 are thermally softened or thermally melted, when a pressure of 0.02 MPa or more accompanied by a shearing force is applied thereto,
The microcapsules 18Y are directly subjected to the burst pressure and are destroyed, releasing the yellow colorant, but the microcapsules 18BK can withstand such burst pressures. On the other hand, the third microcapsule layer portion 16
When the heating temperature for Y / B reaches a temperature exceeding 150 ° C. of the thermal melting temperature of the binder particles 20 and about 190 ° C. of the primary azeotropic point of the black color material of the microcapsules 18BK, for example, 210 ° C., the pressure exerted thereon is 0.02 MPa. With the following pressure, for example, 0.01 MPa, the microcapsules 18Y can withstand without breaking, but the microcapsules 18BK
Due to the increase of the internal pressure, the black color material breaks the wall film and is released.

As schematically shown in FIGS. 2 and 4, the second
The microcapsule layer portion 16M also has a stone wall structure, in which a number of microcapsules 18M enclosing a magenta coloring material and a number of spacer particles 22 are uniformly distributed in the wax type binder particles 24.

As in the case of the microcapsules 18Y and 18BK, the wall film of the microcapsules 18M is also formed of an amino resin colored in the same color (usually white) as the sheet paper 12, and the magenta coloring material enclosed therein is used. Is about 10% (weight percent) magenta dye in a suitable clear oil. As the transparent oil, KMC-113 (2,7 diisopropylnaphthalene) manufactured by Kureha Chemical Co., Ltd. described above is used, and as a magenta dye, Rhodamine Lake T or the like is used. Such a microcapsule 18
M can also be manufactured by the conventional microcapsule manufacturing method described above, and its average particle size is about 6 μm to about 7 μm. 18M with shear
It is assumed that it can be broken under a pressure of 0.2 MPa or more. In the present embodiment, hydroxyapatite is used as the spacer particles 22, and the average particle size of the spacer particles 22 is about 8 μm, which is larger than the average particle size of the microcapsules 18M.
μm to about 9 μm.

On the other hand, the wax type binder particles 24
As, microcrystalline wax is used,
Such binder particles 24 are made of CWP- manufactured by Seishin Enterprise.
3 (Microcrystalline wax powder) with an average particle size of about 3 to about 5 μm
And its hot melt temperature is about 108 ° C. In addition,
The binder particles 24, i.e., microcrystalline wax powder, are white.

The stone wall structure of the second microcapsule layer portion 16M can be obtained by the same method as in the above case. (3) A 3% aqueous solution of polyvinyl alcohol (degree of polymerization 2,000) is prepared. For 100 grams of this adhesive aqueous solution, 5 grams of spacer particles 22 and 10 grams of CWP-3 (microcrystalline wax powder) Then, an appropriate amount, for example, 10 g of microcapsules 18M, and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) are mixed / stirred to prepare a suspension. (2) Spray the suspension in an amount of 2 to 4 grams per square meter on the third microcapsule layer portion 16Y / B and allow it to dry naturally, then put it in a heating oven and heat-melt CWP-3. Heat to a temperature of 103 ° C., somewhat lower than the temperature (about 108 ° C.), and maintain the heated state for about 15 minutes, so that CWP-3 (microcrystalline wax powder), ie, the binder particles 24, heats each other. Fused, thus obtaining a stone wall structure as shown in FIG. Note that, as in the case described above, if the strength of the stone wall structure is sufficient with the adhesive strength obtained with an aqueous solution of polyvinyl alcohol or another adhesive,
Such a heat treatment can be omitted.

Third microcapsule layer portion 16Y / B
As in the case of the second microcapsule layer portion 16M
Also, when the binder particles 24 maintain the solid phase state, that is, when the heating temperature for the second microcapsule layer portion 16M is equal to or lower than the thermal melting temperature of the binder particles 24 of 108 ° C., the second microcapsule layer Even when a breaking pressure of 0.2 MPa or more accompanied by shearing force is applied to the portion 16M, the breaking pressure is not hindered by the stone wall structure of the binder particles 24 and does not directly reach the microcapsules 18M. It is not done. However, when the heating temperature for the second microcapsule layer portion 16M becomes equal to or higher than the heat melting temperature of the binder particles 24 of 108 ° C., the binder particles 24 are thermally softened or melted. When the above pressure is applied, the microcapsules 18M are directly subjected to the breaking pressure and are broken. The function of the spacer particles 22 included in the second microcapsule layer portion 16M will be described later in detail.

As schematically shown in FIGS. 2 and 5, the first
The microcapsule layer portion 16C also has a stone wall structure, in which a large number of microcapsules 1 encapsulating a cyan color material are provided.
8C and many spacer particles 26 are evenly distributed in the wax type binder particles 28.

Microcapsules 18Y, 18BK and 1
As in the case of 8M, the wall film of the microcapsule 18C is also formed of an amino resin colored in the same color (usually white) as the sheet paper 12, and the cyan coloring material encapsulated therein is mixed with a suitable transparent oil. It contains 10% (weight percent) of a cyan dye. As the transparent oil, KMC-113 (2,7 diisopropylnaphthalene) manufactured by Kureha Chemical Co., Ltd. described above is used, and as the cyan dye, phthalocyanine blue or the like is used. Such a microcapsule 18C can also be manufactured by the conventional microcapsule manufacturing method as described above, and has an average particle size of about 3 μm to about 4 μm. Is such that the microcapsules 18C can be broken under a pressure of 2.0 MPa or more with shearing force. Also, as in the case of the above-described spacer particles 22, hydroxyapatite is used as the spacer particles 26, and the average particle size thereof is the microcapsule 18C.
About 5 to 9 μm, which is larger than the average particle size.

On the other hand, the wax type binder particles 28
A paraffin wax having a heat melting temperature of 73 ° C. is used, and such binder particles 28 are obtained by grinding such a paraffin wax material into particles having an average particle size of about 1 μm to about 3 μm by a jet mill. The binder particles 28, that is, the paraffin wax particles are white.

The stone wall structure of the first microcapsule layer portion 16C can be obtained by the same method as in the case described above. (3) A 3% aqueous solution of polyvinyl alcohol (degree of polymerization: 2,000) is prepared. For 100 grams of this adhesive aqueous solution, 5 grams of spacer particles 26, 10 grams of paraffin wax particles (binder particles 28) and appropriate A suspension is prepared by mixing / stirring microcapsules 18C in an amount of, for example, 10 grams, and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate). (2) The above suspension is sprayed on the second microcapsule layer portion 16M in an amount of 1 to 3 grams per square meter and air-dried once, and then placed in a heating oven to form paraffin wax particles (binder particles 28). Is heated to a temperature of 68.degree. C., which is somewhat lower than the hot melt temperature (about 73.degree. C.), and is maintained for about 15 minutes, whereby the paraffin wax particles, i.e., the binder particles 26, are thermally fused to one another, thus. A stone wall structure as shown in FIG. 4 is obtained. Note that, as in the case described above, if the strength of the stone wall structure is sufficient with the adhesive strength obtained with an aqueous solution of polyvinyl alcohol or another adhesive,
Such a heat treatment can be omitted.

Third and second microcapsule layer portions 1
Similarly to the case of 6Y / B and 16M, also in the first microcapsule layer portion 16C, when the binder particles 28 maintain the solid state, that is, the heating temperature for the first microcapsule layer portion 16C is changed to the binder temperature. When the melting temperature of the particles 28 is set to 73 ° C. or lower, even if a breaking pressure of 2.0 MPa or more accompanied by a shearing force is applied to the first microcapsule layer portion 16C, the breaking pressure is maintained at the binder particles 28C.
Does not directly reach the microcapsules 18C because of the stone wall structure of the microcapsules 18C.
Is not destroyed. However, when the heating temperature for the first microcapsule layer portion 16C is 73 ° C. or higher of the binder particles 28, the binder particles 28 are thermally softened or melted. When the above pressure is applied, the microcapsules 18C are directly subjected to the breaking pressure and are broken. The function of the spacer particles 26 included in the first microcapsule layer portion 16C will be described later.

In short, as a final result, the first, second, and third microcapsule layer portions 16C, 16M, and 1 of the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 are obtained.
Microcapsules 18 contained in each of 6Y / B
C, 18M, and 18Y18BK are given the temperature / pressure rupture characteristics as shown in the graph of FIG.

More specifically, as is clear from the graph of FIG. 6, the breaking pressure characteristic curve PC of the wall film of the microcapsule 18C in the first microcapsule layer portion 16C and the first microcapsule layer portion 16C The thermal melting temperature of the contained binder particles 28 is 73 ° C. and the thermal melting temperature of the binder particles 24 contained in the second microcapsule layer portion 16M
108 ° C. defines a cyan coloring region (shaded region) C. When the temperature T ₁ and the pressure P ₃ included in the cyan coloring region C are applied to the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, There are microcapsules 18
Only C is destroyed and the cyan material is released.

As is clear from the graph of FIG.
The burst pressure characteristic curve PC of the wall film of the microcapsules 18C in the first microcapsule layer portion 16C and the microcapsules 18 in the second microcapsule layer portion 16M
M, the burst pressure characteristic curve PM of the wall film, the heat melting temperature of the binder particles 24 contained in the second microcapsule layer portion 16M of 108 ° C., and the third microcapsule layer portion 16Y
/ By the thermal melting temperature 0.99 ° C. of the binder particles 20 contained in B, defined magenta color region (shaded area) M is, the temperature T ₂ and pressure P ₂ is sensitive pressure sensitive heat storage medium contained in the magenta color region M 10 microcapsule layers 1
4, when there are microcapsules 18M
Only the magenta colorant is released.

Similarly, as is apparent from the graph of FIG. 6, the burst pressure characteristic curve PM of the wall film of the microcapsule 18M in the second microcapsule layer portion 16M and the third pressure characteristic curve PM
Of the wall pressure of the microcapsule 18Y in the microcapsule layer portion 16Y / B, the thermal melting temperature of the binder particles 20 contained in the third microcapsule layer portion 16Y / B, 150 ° C. by the primary azeotropic point 190 ° C. black coloring material of the microcapsules 18BK in the microcapsules layer 16Y / B of, yellow - color regions (hatched regions) Y is defined, the yellow - temperature T ₃ included in the color area Y And the pressure P ₁ are the pressure-sensitive thermosensitive recording medium 10
Of the microcapsule layer 14, only the microcapsules 18Y are destroyed and the yellow colorant is released.

Further, as shown in the graph of FIG. 6, the breakdown pressure characteristic curve PY of the wall film of the microcapsule 18Y in the third microcapsule layer portion 16Y / B and the third microcapsule layer 16Y / B Microcapsule 18B
The primary azeotropic point of 190 ° C. of the black color material of K defines a black coloring region (hatched region) BK, and the temperature T ₄ and the pressure P ₀ contained in the black coloring region BK are reduced by When affected on the capsule layer 14, only the microcapsules 18BK are destroyed, releasing the black colorant. That is, when the heating temperature is equal to or higher than the primary azeotropic point (about 190 ° C.) of the black color material, the microcapsules 18BK break themselves and emit the black color material due to a rapid increase in the internal pressure.

In the graph of FIG. 6, the burst pressure characteristic curve of the wall film of the microcapsule 18BK is indicated by reference numeral PBK. The thickness is such that the microcapsules 18BK can withstand pressures of at least P ₃ , P ₂ and P ₁ at temperatures T ₁ , T ₂ and T ₃ , respectively.
Normally, the primary azeotropic point of black colorant oil (about 190
C), the microcapsules 18BK will not be destroyed.

In short, as is clear from the graph of FIG. 6, by appropriately selecting the temperature and pressure to be applied to the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, the microcapsules contained in the microcapsule layer 14 can be selected. 18C, 18M, 18Y and 18BK can be selectively destroyed. In the second embodiment, each of the temperatures T ₁ , T ₂ , T ₃ and T ₄ is set to, for example, 90 ° C., 130 ° C., 170 ° C. and 210 ° C., and the pressures P ₀ , P ₁ , P ₂ and for each of P _3, for example 0.01 MPa, 0.1 MPa, it is set to 1.0MPa and 3.0 MPa.

Referring to FIG. 7, there is shown a pressure-sensitive thermal recording apparatus for recording a color image on the pressure-sensitive thermal recording medium 10 described above, and this pressure-sensitive thermal recording apparatus is configured as a color line printer. .

As shown in FIG. 7, the pressure-sensitive thermosensitive recording apparatus includes a housing 20 having a substantially rectangular shape. 22 are formed. Also, housing 2
A discharge port 24 for discharging the pressure-sensitive and heat-sensitive recording medium 10 is formed in one of the side walls 0. In FIG. 7, the movement path of the pressure-sensitive thermosensitive recording medium 10 is indicated by a dashed-dotted line 26. Later outlet 2
It is discharged from 4.

In the housing 20, a thermal head support 28 is provided at a predetermined position, and a part of the moving path 26 is defined by the thermal head support 28. A first thermal head 30C, a second thermal head 30M, a third thermal head 30Y, and a fourth thermal head 30B are mounted on the thermal head support 28 from the inlet 22 to the outlet 24, and each thermal head 30B The head extends in a direction crossing the moving path of the pressure-sensitive thermosensitive recording medium 10, and a number of electric resistance elements, that is, heating elements are arranged in a straight line along the extending direction. Note that the first and second
Each of the third thermal heads 30C, 30M, 30Y and 30B includes n heating elements.

Referring to FIG. 8, some of the n heating elements included in the first thermal head 30C are indicated by reference numerals R _c1 , R _c2 and R _c3 , and the second thermal head 3
Some of the n heating elements included in 0M are denoted by reference symbols R _m1 ,
Some of the n heating elements indicated by R _m2 and R _m3 and included in the third thermal head 30Y are indicated by reference symbols R _y1 , R _y2 and R _y3 and are included in the fourth thermal head 30B. Some of the n heating elements are denoted by reference characters R _b1 , R _b2 and R _b3.
Indicated by As is clear from FIG. 8, n heating elements R _c1 , R _c2 , R _c3 ,... R _cn , n heating elements R _m1 ,
R _m2 , R _m3 ,... R _mn , n heating elements R _y1 , R _y2 ,
R _y3, ... R _yn and n number of heating elements _{R b1, R b2, R b3} , ...
R _bn are arranged in a matrix of 4 rows and n columns, and three corresponding heating elements (for example, R
_c2 , _Rm2 , _Ry2, and _Rb2 ) are aligned with each other along the moving direction of the pressure-sensitive thermosensitive recording medium 10.

The n heating elements R _c1 , R _c2 , R _c3 ,... R _cn of the first thermal head 30C are connected to a first thermal head drive circuit 31C. , N heating elements R _c1 , R _c2 , R
_c3 ,... _Rcn are selectively energized in accordance with one line of cyan pixel data to generate heat. The heat generation temperature is 73 ° C., which is the heat melting temperature of the binder particles 28 included in the first microcapsule layer portion 16C. Of the binder particles 24 contained in the microcapsule layer portion 16M of No. 2 at 108 ° C.
And T ₁ (90 ° C.).

The n heating elements R _m1 , R _m2 , R _m3 ,... R _mn of the second thermal head 30M are connected to a second thermal head drive circuit 31M. , N heating elements R _m1 , R _m2 , R
_m3 ,..., _Rmn are selectively energized in accordance with one line of magenta pixel data to generate heat.
The temperature T ₂ (130) between the hot melting temperature of the binder particles 24 contained in the microcapsule layer portion 16M of the _second embodiment and the hot melting temperature of the binder particles 20 contained in the third microcapsule layer portion 16Y / B is 150 ° C. ° C).

[0072] The third n-number of the thermal head 30Y of the heating elements _{R y1, R y2, R y3} , ... R yn is connected to the third thermal head drive circuit 31Y, the third thermal head drive circuit 31Y , N heating elements R _y1 , R _y2 , R
_y3 ,... _Ryn are selectively energized in accordance with one line of yellow pixel data to generate heat.
Of the binder particles 20 contained in the microcapsule layer portion 16Y / B of the microcapsule 18
Temperature T between the primary azeotropic point of black colorant of BK and 190 ° C
₃ (170 ° C).

The n heating elements R _b1 , R _b2 , R _b3 ,... R _bn of the fourth thermal head 30B are connected to a fourth thermal head drive circuit 31B. , N heating elements R _b1 , R _b2 , R
_b3 ,... R _bn are selectively energized in accordance with one line of black pixel data to generate heat.
Of the black color material of the microcapsules 18BK contained in the microcapsule layer portion 16Y / B of the first colorant 190 ° C.
T ₄ (210 ° C.) that exceeds

As shown in FIG. 7, a first roller platen 32C is applied to the first thermal head 30C, and a first pressure applying spring means 34C is combined with the first roller platen 32C. The first pressure applying spring means 34C is configured to exert a pressure P ₃ (3.0 MPa) of greater than 2.0MPa relative to the first roller platen 32C, whereby the first roller platen 32C is a pressure P ₃ (3.0 M
Pa), the first thermal head 30C is pressed against the first thermal head 30C.

A second roller platen 32M is applied to the second thermal head 30M, and a second pressure applying spring means 34M is combined with the second roller platen 32M. Second pressure applying spring means 34M is configured to exert pressure P ₂ (1.0 MPa) between the pressure 0.2MPa and pressure 2.0MPa relative to the second roller platen 32M, thereby the second roller platen 32M is pressure P ₂ (1.0MP
In a), the thermal head is pressed against the second thermal head 30M.

A third roller platen 32Y is applied to the third thermal head 30Y, and a third pressure applying spring means 34Y is combined with the third roller platen 32Y. The third pressure applying spring means 34Y is configured to apply a pressure P ₁ (0.1 MPa) between 0.02 MPa and 0.2 MPa to the third roller platen 32Y, thereby forming the third roller platen 32Y. Is the pressure P ₁ (0.1MPa)
Is pressed against the third thermal head 30Y.

A fourth roller platen 32B is applied to the fourth thermal head 30B, and a fourth pressure applying spring means 34B is combined with the fourth roller platen 32B. The fourth pressure applying spring means 34B applies a pressure of less than 0.02 MPa to the fourth roller platen 32B,
That is, the pressure P at which all microcapsules cannot be broken
₀ (0.01 MPa), whereby the fourth roller platen 32B is pressed against the fourth thermal head 30B at a pressure P ₀ (0.01 MPa).

At the time of recording a color image on the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, each of the above-described heating elements is a pixel unit (that is, a dot) of the color image.
It has a dimensional shape corresponding to. That is, as described below,
The heat generated by each heating element causes a dot as a pixel unit to be generated on the microcapsule layer 14. In the present embodiment, each heating element is given a size and shape such that the dot size is about 50 μm to about 100 μm. Can be

In FIG. 7, reference numeral 36 denotes the first, second, third and fourth thermal heads 30C and 30C.
A control circuit board for controlling the driving of M, 30Y, 30B, etc. is shown, and reference numeral 38 denotes a power supply device, and the power supply device 38 allows the first, second, third and fourth thermal heads 30C, Power is supplied to the respective heating elements 30M, 30Y, and 30B, the control circuit board 36, and the like.

As described above, when recording a color image, the pressure-sensitive thermosensitive recording medium 10 is introduced into the inlet 22. At this time, the direction of the pressure-sensitive thermosensitive recording medium 10 is such that the microcapsule layer 14 side is the first side. , Second, third, and fourth thermal heads 30C, 30M, 30Y, and 30B ( _Rc1 ,... _Rcn ; _Rm1 ,... _Rmn ; _Ry1,.
R _yn ; R _b1 ,... R _bn ).

Next, a description will be given of a coloring process when full-color coloring is performed on the pressure-sensitive thermosensitive recording medium 10 using the above-described pressure-sensitive thermosensitive recording apparatus.

When the pressure-sensitive thermosensitive recording medium 10 passes between the first thermal head 30C and the first roller platen 32C, the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 is moved by the first pressure applying spring means. The heating elements _Rc1 , _Rc2 , _Rc3 ,... R of the first thermal head 30C for 34C.
Although will undergo breaking pressure P ₃ with the shear force (3.0 MPa) from _cn, the breaking pressure P ₃ microcapsule layer 1
4 does not directly affect each of the microcapsules 18C, 18M, 18Y, and 18BK because of the stone wall structure of the binder particles (20, 24, 28).

However, when one of the heating elements R _c1 , R _c2 , R _c3 ,... R _cn of the first thermal head 30C is energized, the energized heating elements (R _{c1 ,.} Temperature T ₁ (90 ° C.) higher than the thermal melting temperature 73 ° C. of binder particles 28 contained in first microcapsule layer portion 16C.
, And the binder particles 28 contained in the application area of the heating element (R _c1 ,..., R _cn ) are thermally softened or thermally melted to form a stone wall structure (the first microcapsule layer portion 16C) of the application area. ) is destroyed, this time the heat generating element (R _c1, ... R _cn) pressure P ₃ with the shear force thereto microcapsules 18C with entering the first microcapsule layer portion 16C as shown in FIG. 9 (3.0MPa). Thus, the microcapsule 18C that has received the breaking pressure P ₃ (3.0 MPa) is broken, and the cyan coloring material is released from there, and the cyan dot is developed there.

Although FIG. 9 does not show a wax hot melt produced by hot melting of the binder particles 28 to avoid complicating the drawing, the first and second microcapsule layer portions 16C and 16M are not shown. Will penetrate into the voids of the stone wall structure.

When the pressure-sensitive thermosensitive recording medium 10 passes between the second thermal head 30M and the second roller platen 32M, the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 is moved by the second pressure applying spring means. The heating elements _Rm1 , _Rm2 , _Rm3 ,... R of the second thermal head 30M for 34M.
Although will undergo breaking pressure P ₂ with the shear force (1.0 MPa) from _mn, the breaking pressure P ₂ is a microcapsule layer 1
4 are blocked by the stone wall structure of the binder particles (20, 24, 28) in Microcapsules 18C, 18M, 18 and 1.
It does not directly affect each of the 8BKs.

[0086] However, the heating elements of the second thermal head _{30M R m1, R m2, R} m3, ... When any of R _mn is energized, the energized heating element (R _m1, ... R _mn) is First and second microcapsule layer portions 16C and 16M
Thermal melting temperature of binder particles 28 and 24 included in each (73 ° C. and 108 ° C.) higher than the temperature T ₂ (130
° C), so that the heating elements (R _m1 , ...
R _mn ) binder particles 28 and 24 included in the application area
Is thermally softened or melted to form a stone wall structure in the application area (the first and second microcapsule layer portions 16C and 1C).
6M) is destroyed, and the heating elements (R _m1 ,... R
_mn ) penetrates the first and second microcapsule layer portions 16C and 16M as shown in FIG. 10 and exerts a breaking pressure P ₂ (1.0 MPa) accompanied by a shearing force on the microcapsules 18C and 18M. Although microcapsules 18C as described above can withstand the burst pressure P ₂ (1.0 MPa), but the microcapsules 18M which receives the burst pressure P ₂ (1.0 MPa) is broken, magenta color material is released therefrom Then, magenta dots are colored there.

Although FIG. 10 does not show a wax hot melt produced by hot melting of the binder particles 28 and 24 to avoid complication of the drawing, the first, second and third microcapsules are not shown. Layer portions 16C, 16M and 16
It will penetrate into the voids of the Y / B stone wall structure.

When the pressure-sensitive thermosensitive recording medium 10 passes between the third thermal head 30Y and the third roller platen 32Y, the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 is moved by the third pressure applying spring means. The heating elements _Ry1 , _Ry2 , _Ry3 ,... R of the third thermal head 30Y for 34Y.
Although will undergo breaking pressure P ₁ with a shear force (0.1 MPa) from _yn, the breaking pressure P ₁ is a microcapsule layer 1
4 does not directly affect each of the microcapsules 18C, 18M, 18Y, and 18BK because of the stone wall structure of the binder particles (20, 24, 28).

[0089] However, the heating elements R _y1 of the third thermal head _{30Y, R y2, R y3,} ... When any of R _yn is energized, the energized heating elements (R _y1, ... R _yn) is The first, second and third microcapsule layer portions 16C, 1
The thermal melting temperatures of the binder particles 28, 24 and 20 contained in 6M and 16Y / B, respectively (73 ° C., 108 ° C., 150 ° C.)
° C.) is heated to a temperature T ₃ (170 ℃) than, Therefore the heat generating element (R _y1, ... binder particles 28, 24 and 20 included in the application area of the R _yn) is thermally softened or hot melt Stone wall structure of the application area (first, second and third microcapsule layer portions 16C, 16M and 16Y / B
Is destroyed, and the heating element (R _y1 ,... R _yn )
Penetrates into the first, second and third microcapsule layer portions 16C, 16M and 16Y / B as shown in FIG. 11 and the microcapsules 18C, 18M, 18Y therein.
And 18BK at a burst pressure P ₁ (0.1 MPa) accompanied by shearing force. As described above, the microcapsules 18C, 18
M and 18BK can withstand the burst pressure P ₁ (0.1 MPa), but the microcapsules 18Y that have received the burst pressure P ₁ (0.1 MPa) are broken, from which yellow colorant is released, There yellow dots are developed.

Although FIG. 11 does not show the wax hot melt produced by the heat melting of the binder particles 28, 24 and 20 in order to avoid complicating the drawing,
Second and third microcapsule layer portions 16C, 16M
And 16Y / B in the gaps of the stone wall structure and the structure of the sheet paper 12.

When the pressure-sensitive thermosensitive recording medium 10 passes between the fourth thermal head 30B and the fourth roller platen 32B, the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 is moved by the fourth pressure applying spring means. The heating elements _Rb1 , _Rb2 , _Rb3 ,... R of the fourth thermal head 30B for 34B.
_bn receives a breaking pressure P ₀ (0.01 MPa) accompanied by a shearing force. The breaking pressure P ₀ is blocked by the stone wall structure of the binder particles (20, 24, 28) in the microcapsule layer 14 and causes It does not directly affect each of the capsules 18C, 18M, 18Y and 18BK.

However, when one of the heating elements R _b1 , R _b2 , R _b3 ,... R _bn of the fourth thermal head 30B is energized, the energized heating elements (R _{b1 ,.} The first, second and third microcapsule layer portions 16C, 1
The temperature T ₄ (2) which is higher than the thermal melting temperature of the binder particles 28, 24 and 20 contained in 6M and 16Y / B, respectively.
10 ° C.), so that the heating elements (R _y1,.
The binder particles 28, 24, and 20 contained in the application region of R _yn are thermally softened or melted to form a stone wall structure (the first, second, and third microcapsule layer portions 1) in the application region.
6C, 16M and 16Y / B) are destroyed. At this time, the heating elements (R _b1 ,..., R _bn ) are connected to the first, second and third microcapsule layer portions 16C, 1B as shown in FIG.
It penetrates 6M and 16Y / B and exerts a burst pressure P ₀ (0.01 MPa) with shear force on the microcapsules 18C, 18M, 18Y and 18BK therein. As described above, the microcapsules 18C, 18M, and 18Y can withstand the breaking pressure P ₀ (0.01 MPa), so that the microcapsules are not broken. On the other hand, the microcapsules 18BK are heated to a temperature T ₄ (210 ° C.) which is higher than the primary azeotropic point (about 190 ° C.) of the black coloring material, so that the internal pressure of the microcapsules 18BK rapidly increases, and thus the microcapsules 18BK Under the pressure P ₀ (0.01 MPa), it breaks down due to a sudden rise in its internal pressure, and its black color material breaks its wall film and is released, whereupon black dots develop color.

In general, black dots can be obtained by superimposing three primary color dots, that is, a cyan dot, a magenta dot and a yellow dot, but as is well known, a true color is obtained by mixing the three primary colors. It is considered difficult to develop black color. Therefore, according to the second embodiment, the third microcapsule layer portion 16
Microcapsule 18 with Y / B filled with black colorant
A true black black dot can be obtained by distributing and selectively destroying BK.

Incidentally, the destruction of the microcapsule 18BK depends largely on its sudden increase in internal pressure. Even if the pressure P ₀ (0.01 MPa) is involved in the destruction, it is not an important factor itself. . In short, the pressure P ₀ is set to 0.01 MPa as an appropriate value, but when the pressure-sensitive thermosensitive recording medium 10 is interposed between the fourth thermal head 30B and the fourth roller platen 32B, The rotation of the fourth roller platen 32B allows the pressure-sensitive thermosensitive recording medium 10 to be surely moved along the moving path 26 and the fourth thermal head 30B.
The fourth roller platen 32B moves the fourth thermal head 30B so that the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 can be appropriately pressed against the heating elements (R _b1 ,..., R _bn ). It is enough if it is pressed.

Thus, a full-color image is formed on the microcapsule layer 14 of the pressure-sensitive and heat-sensitive recording medium 10 by three primary color dots, that is, cyan dots, magenta dots, yellow dots, and black dots, which are developed based on the color pixel signals. You will get it. Needless to say, in such a full-color image, a blue dot is obtained by superimposing a cyan dot and a magenta dot,
A green dot is obtained by superimposing a cyan dot and a yellow dot, and a red dot is obtained by superimposing a magenta dot and a yellow dot.

Here, the function of the spacer particles 26 and 22 included in the first and second microcapsule layer portions 16C and 16M will be described.

For example, the heating elements R _m1 , R _m2 , and R _{m of} the second thermal head 30M are provided so that only the magenta dots are colored on the microcapsule layer 14 of the pressure-sensitive thermal recording medium 10.
_When any of _m3 ,... _Rmn is energized, first, the binder particles 28 in the first microcapsule layer portion 16C are thermally softened or heated by the energized heating elements ( _Rm1 ,... _Rmn ). After being melted, the binder particles 24 in the second microcapsule layer portion 16M are thermally softened or melted. That is, the heating elements (R _m1 ,...)
R _mn) is the heater element until entering the second microcapsule layer portion 16M as shown in FIG. 10 (R _m1, ... R
_mn ) enters the first microcapsule layer portion 16C (ie, the state as shown in FIG. 9) transiently appears for a moment. At this time, the microcapsules 18C in the first microcapsule layer portion 16C are subjected to a breaking pressure P ₂ accompanied by a shearing force.
(1.0MPa), microcapsule 1
As described above, the wall film of 8C has a pressure P ₂ (1.
Since the film thickness can withstand 0 MPa), the microcapsules 18C cannot be broken in principle.

However, the average particle size of the microcapsules 18C is about 3 μm to 4 μm as described above.
However, the microcapsules 18C may include those having an exceptionally large particle size. In addition, in the attached drawings, the microcapsules (18C, 18M, 18Y) of each color are simply shown as a uniform particle size. The microcapsule layer portion 16C is a heating element (R _m1 ,..., R _mn ).
When a shear force due to the relative movement between the microcapsules 18C and the pressure-sensitive thermosensitive recording medium 10 is applied, pressure accompanying the shear force is intensively applied to the microcapsules 18C having an exceptionally large particle size. As a result, even though the set pressure is P ₂ (1.0 MPa), the microcapsules 18C having exceptionally large particle diameters are subjected to a higher pressure, and the microcapsules 18C are erroneously destroyed. Sometimes. Of course, the cyan coloring material emitted due to such erroneous destruction of the microcapsule 18C appears as noise in the magenta image.

In the present embodiment, in order to minimize the generation of such noise, the spacer particles 26 having a particle size slightly larger than the average particle size of the microcapsules 18C are used as the first microcapsule layer portions 16C. The heating elements (R _m1 ,... R _mn ) are distributed in the first microcapsule layer portion 1 due to the presence of such spacer particles 26.
The pressure concentration on the exceptionally large particle size microcapsules in the transient state that has penetrated 6C can be eliminated as much as possible. In short, the microcapsules 18C having an exceptionally large particle diameter can be minimized from receiving an inadvertent shear force due to the relative movement between the heating elements ( _Rm1 ,... _Rmn ) and the pressure-sensitive thermosensitive recording medium 10.

The same applies to the spacer particles 22 included in the second microcapsule layer portion 16M. That is, when only yellow dots are to be formed on the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10,
The microcapsules in the second microcapsule layer portion 16M are provided in order to prevent the magenta color material released due to the erroneous destruction of the microcapsules 18M having exceptionally large particle sizes from appearing as noise in the yellow image as much as possible. Capsule 18M
Spacer particles 2 having a particle size slightly larger than the average particle size of
2 are distributed.

Of course, if microcapsules 18C or 18M can be obtained with uniform particle size, that is, if microcapsules having exceptionally large particle sizes can be excluded from each type of microcapsules, The first microcapsule layer portion 16C or the second
The spacer particles (26, 22) can be omitted from each of the microcapsule layer portions 16M.

Further, as is apparent from the above description, the average burst diameters of the microcapsules 18C, 18M and 18Y are determined at the respective set burst pressures P ₁ , P ₂ and P _3.
The size of the microcapsules (18C, 18M, 18C) is gradually increased as the
The effect that the false color development of Y) can be positively prevented is also obtained. For example, when the microcapsule 18Y is destroyed,
The set burst pressure P ₁ is the maximum size of microcapsule 1
Since the microcapsules 18C and 18M having smaller particle diameters are received by 8Y, the microcapsules 18C and 18M are less susceptible to the pressure caused by the shearing force, and thus the microcapsules 18C and 18M are less likely to be erroneously destroyed.

In the above-described second embodiment, phthalocyanine blue is used as the cyan dye of the cyan color material, rhodamine lake T, yellow is used as the magenta dye of the magenta color material.
Benzine yellow-G is used as the yellow pigment of the color material, and carbon black is used as the black pigment. It is also possible to use a leuco dye having the following properties. As mentioned earlier,
The leuco dye itself is usually milky or translucent, and such a leuco dye emits each color by a chemical reaction with a developer. For example, leuco dyes for cyan coloring include benzoyl leuco methylene blue (BLMB) and crystal violet lactone (CVL), and leuco dyes for magenta coloring include R-500 and Yamada Chemical Co., Ltd. Red-3 made by Yamamoto Kasei,
As leuco dyes for yellow-coloring, IR-3 (Pergascript Yellow) manufactured by Ciba-Geigy and Fcolor Yellow 17 manufactured by Yamamoto Kasei are used. As leuco dyes for black coloring, BlacK manufactured by Yamamoto Kasei is used. 15 are mentioned. Of course, when a leuco dye is used, colorless zinc salicylate, activated clay or the like may be used as a color developer in the first, second and third colors.
Microcapsule layer portions 16C, 16M and 16Y /
B.

When a leuco dye is used,
The wall film material of the microcapsules (16C, 16M, 16Y) of each color is preferably transparent, and in this case, the microcapsules (16C, 16M, 16Y) of each color show what color the sheet paper 12 exhibits. However, it is not necessary to give any consideration to the coloring of the wall film material.

In the above-described second embodiment, KMC-113 manufactured by Kureha Chemical Co., Ltd. is used as a vehicle (transparent oil) for the cyan, magenta and yellow coloring materials. Of course, suitable high boiling clear oils can be used. Also, instead of transparent oil as a vehicle for cyan, magenta and yellow coloring materials,
May be used low-melting wax but, in that case as the low melting wax, which hot-melt is chosen with a color minimum temperatures T ₁ below.

Further, in the above-described second embodiment, polypropylene wax, microcrystalline wax and paraffin wax are used as the wax material of the binder particles 20, 24 and 28. If so, other wax materials such as montan wax, carbana wax and the like may be used. On the other hand, as a material of the binder particles (20, 24, 28), a low melting point thermoplastic resin, not a wax material,
For example, ethylene-vinyl-acetate copolymer (EVA
), Polyethylene, polyester, polymethyl methacrylate copolymer, etc.
However, in that case, it is a matter of course that the low melting point thermoplastic resin to be used has a desired heat melting temperature.

Microcapsules (18C, 18M, 18
As the wall film material of Y), it is possible to use a high melting point thermoplastic resin which is not thermoplasticized at least at 250 ° C., for example, a polyamide resin, a polyimide resin, etc., instead of the thermosetting resin. In this case, of course, the condition is that the high melting point thermoplastic resin to be used can exhibit a desired burst pressure characteristic curve (PC, PM, PY, PBK).

In the second embodiment described above, hydroxyapatite is used as the material of the spacer particles (22, 26). However, other inorganic materials, such as silica, calcium carbonate, and titanium dioxide, are used. Alternatively, a suitable resin material such as polyimide, polyamide, Teflon, and polycarbonate may be used.

Further, various additives are added to each microcapsule layer portion (1) in order to improve the reliability of the pressure-sensitive thermosensitive recording medium 10 and to improve the image quality of an image to be recorded thereon.
6C, 16M, 16Y / B).
For example, as such an additive, an adhesion inhibitor for preventing the adhesion of the molten wax and the emission color material to the heating element of each thermal head (30C, 30M, 30Y, 30B), and the emission color material are quickly adsorbed. Fixing agents (so-called fillers) to be fixed by the above-mentioned method, ultraviolet inhibitors and antioxidants for preventing fading of recorded images.

Furthermore, in the above-described second embodiment, the first, second, and third microcapsule layer portions 16C, 1C
Although each of 6M and 16Y / B has a stone wall structure, each microcapsule layer portion (16C, 16M, 16
Y / B), each corresponding microcapsule (18C, 18M, 18Y / B) and, if necessary, a spacer particle (26, 28)) may be formed as a solid wax binder layer uniformly distributed. Good.

For example, the third microcapsule layer portion 1
The case where 6Y / B is formed as a solid wax binder layer will be described. For 100 grams of an aqueous adhesive solution, 20 grams of PPW-5 (polypropylene wax powder) and a predetermined amount (eg, 10 grams) of micro A suspension obtained by mixing / stirring the capsule 18Y, a predetermined amount (for example, 10 grams) of the microcapsules 18BK, and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) is placed on the sheet paper 12 at about 5 grams per square meter. Spray it once and let it dry naturally, then put it in a heating oven and heat it up to at least the hot melting temperature of PPW-5 (polypropylene wax powder) (about 150 ° C). Is set. Thus, PPW-5 is completely melted by heat to form a solid wax binder layer (that is, a solid polypropylene wax layer), in which the microcapsules 18Y are uniformly distributed.

In a similar manner, the second and first microcapsule layer portions 16M and 16C can also be formed as solid wax binder layers. That is, in order to make the second microcapsule layer portion 16M a solid wax binder layer, the third microcapsule layer 16Y
After applying a suspension containing CWP-3 (microcrystalline wax powder) on the (solid polypropylene wax layer) and allowing it to dry naturally, the heat melting temperature of CWP-3 (about 10
8 [deg.] C.) or more, and the first microcapsule layer portion 16C is formed on the second microcapsule layer 16M (solid wax binder layer) in order to form a solid wax binder layer. The suspension containing the paraffin wax particles may be applied and air-dried, and then heated at a heating temperature equal to or higher than the heat melting temperature (about 73 ° C.) of the paraffin wax particles.

When each microcapsule layer portion (16C, 16M, 16Y) is formed as a solid wax binder layer as described above, the breaking pressure of the microcapsules contained in each solid wax binder layer is limited. It is necessary to set it slightly higher. That is, when a predetermined pressure is applied to the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, the pressure applied as a breaking pressure to the microcapsules in each solid wax binder layer and the pressure in each stone wall structure This is because the former is somewhat smaller than the pressure applied to the microcapsules as the breaking pressure.

As is clear from the above description, in the second embodiment, the average particle size (about
1 μm to about 3 μm) is the minimum value as compared with the average particle size of the other microcapsules 18C, 18M and 18Y.
The presence of K does not affect the burst pressure characteristics of the other microcapsules 18C, 18M and 18Y. This is because if the microcapsule 18BK is made larger than the average particle size of the other microcapsules 18C, 18M and 18Y,
The BK has the same function as the spacer particles 26 and 28, and the predetermined microcapsules (18C, 18M, 1
8Y) when microcapsules 18B are to be destroyed
This is because the existence of K may cause a situation that can be avoided from destruction.

Furthermore, in the second embodiment, the microcapsules 18 BK are provided in the third microcapsule layer portion 16.
Y / B, but microcapsules 18
The BK itself may be distributed in the first microcapsule layer portion 18C or the second microcapsule layer portion 18M, or may be distributed throughout the first, second and third microcapsule layer portions 18, 18M and 19Y. It may be distributed.

Referring to FIG. 12, a third embodiment of a pressure-sensitive thermosensitive recording medium according to the present invention is indicated generally by the reference numeral 40, wherein the pressure-sensitive thermosensitive recording medium 40 comprises a suitable support such as a sheet of paper 42. And a microcapsule layer 44 applied to one surface of the sheet paper 42. In the third embodiment, the microcapsule layer 44 has a two-layer structure for recording a full-color image thereon. That is,
The microcapsule layer 44 includes a first microcapsule layer portion 46C for recording a cyan image, and a second microcapsule layer portion 46M / Y for selectively recording a magenta image and a yellow image, A second microcapsule layer portion 46M / Y is first formed on the surface of the sheet paper 42, and then a first microcapsule layer portion 46C is formed on the second microcapsule layer portion 46M / Y.

As schematically shown in FIGS. 12 and 13,
The second microcapsule layer portion 46M / Y has a stone wall structure, in which a number of microcapsules 48M enclosing a magenta color material and a number of microcapsules 48Y enclosing a yellow color material are formed of a wax type binder. It is evenly distributed in the particles 50.

The microcapsules 48M have substantially the same configuration as the microcapsules 18M in the above-described second embodiment. That is, the wall film of the microcapsules 48M is formed of an amino resin colored in the same color (usually white) as the sheet paper 42, and the magenta coloring material enclosed therein is KMC-113 (2, manufactured by Kureha Chemical Co., Ltd.). 7 diisopropylnaphthalene) mixed with about 10% (weight percent) of a magenta dye such as rhodamine lake T. The average particle size of the microcapsules 48M is about 6 μm to about 7 μm.
The thickness of the wall film is such that the microcapsules 48Y can be broken under a pressure of 0.2 MPa.

The wall film of the microcapsule 48Y is also formed of an amino resin colored in the same color (usually white) as the sheet paper 12, and the yellow coloring material enclosed therein is about 10% (approx. (Percent by weight) of yellow dye. As the transparent oil, KMC-113 manufactured by Kureha Chemical Co., Ltd., that is, 2,7 diisopropyl naphthalene (boiling point: about 300 ° C.) is added with n-heptane at a ratio of 20% so that the primary azeotropic point becomes about 150 ° C. The yellow pigment is benzene yellow.
G or the like is used. The average particle size of the microcapsules 48Y is about 1 μm to about 3 μm, and the thickness of the wall film is such that the microcapsules 48Y can withstand a pressure of at least 0.2 MPa at a temperature of 150 ° C. or less. However, when heated to a temperature higher than the boiling point (about 150 ° C.) of the yellow colorant oil encapsulated therein, it can be easily broken by its internal pressure. In short, the microcapsules 48Y are of substantially the same type as the heat-sensitive microcapsules 8 used in the first embodiment, and have a primary azeotropic point of 150 ° C. for the yellow coloring material. Note that, in order to obtain a desired boiling point, xylene, benzene, naphthalene, or the like having a boiling point lower than that of KMC-113 can be used instead of n-heptane as in the case described above.

On the other hand, the wax type binder particles 50
As, microcrystalline wax is used,
Such binder particles 50 are CWP- manufactured by Seishin Enterprise Co., Ltd.
3 (Microcrystalline wax powder) with an average particle size of about 3 to about 5 μm
And its hot melt temperature is about 108 ° C. That is,
The binder particles 50 are the same as the binder particles 24 used in the second microcapsule layer 16M in the second embodiment.

The stone wall structure of the second microcapsule layer portion 46M can be obtained by the same method as in the case described above. (3) Prepare a 3% aqueous solution of polyvinyl alcohol (degree of polymerization 2,000), and add 10 grams of CWP-3 (microcrystalline
Wax powder), a predetermined amount (for example, 10 grams) of microcapsules 48M, a predetermined amount (about 10 grams) of microcapsules 48Y, and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) are mixed / stirred. To prepare a suspension. ■ Spray the above suspension on sheet paper 42 in an amount of about 5 grams per square meter and allow it to dry naturally, then put it in a heating oven and heat it to the heat melting temperature of CWP-3 (about
108 ° C) to a temperature somewhat lower than 103 ° C, and the heating is maintained for about 15 minutes, whereby CWP-3
(Microcrystalline wax powder), that is, the binder particles 50 are thermally fused to one another and thus FIG.
A stone wall structure as shown in FIG. 3 is obtained.

Second microcapsule layer portion 46M / Y
In the above, when the binder particles 50 maintain the solid state, that is, the second microcapsule layer portion 46M / Y
Is the heating temperature of the binder particles 50,
When the pressure is set to not more than 0.2 ° C., even if a pressure (with a shearing force) that greatly exceeds 0.2 MPa is applied to the second microcapsule layer portion 46M / Y, the pressure is maintained at the solid binder particles 5.
The microcapsules 48M are not broken because they are supported by zero. However, when the heating temperature for the second microcapsule layer portion 48M / Y is equal to or higher than the heat melting temperature of the binder particles 50 of 108 ° C., the primary azeotropic point (about 15
0 ° C.) or less, the binder particles 50 are thermally softened or melted.
When pressure of Pa or more is applied, the microcapsules 48M
Is directly destroyed by the breaking pressure.

On the other hand, even if the binder particles 50 are thermally melted, if the heating temperature is lower than the primary azeotropic point (about 150 ° C.) of the yellow color material of the microcapsules 48Y, the microcapsules 48Y can withstand a pressure of 0.2 MPa. So it won't be destroyed. Second microcapsule layer portion 46M
When the heating temperature for / Y is higher than the primary azeotropic point (about 150 ° C.) of the yellow colorant oil of the microcapsules 48Y and the pressure applied thereto is 0.2 MPa or less, the microcapsules 48M are not broken and Capsules 48
Only Y will be destroyed. That is, when the heating temperature exceeds the primary azeotropic point (about 150 ° C.) of the yellow colorant,
The microcapsules 48Y are destroyed by themselves due to a sudden increase in internal pressure.

As schematically shown in FIGS. 12 and 14,
The first microcapsule layer 46C also has a stone wall structure,
There, a large number of microcapsules 48C enclosing a cyan colorant and spacer particles 54 are uniformly distributed in the wax type binder particles 52.

As in the case of the microcapsules 48Y and 48M, the wall film of the microcapsule 48C is
Formed from an amino resin colored the same color (usually white) as 2, the encapsulated cyan material is a suitable transparent oil mixed with about 10% (weight percent) cyan dye. As a transparent oil, KM manufactured by Kureha Chemical Co., Ltd.
C-113 (2,7 diisopropylnaphthalene) is used, and phthalocyanine blue or the like is used as a cyan dye. The average particle size of the microcapsules 48C is about 3 μm to about 4 μm, and the thickness of the wall film of the microcapsules 48C is about
Can be broken under a pressure of 2.0 MPa or more with shear force. Hydroxyapatite is used as the spacer particles 52, and the average particle size thereof is about 5 μm to 6 μm, which is larger than the average particle size of the microcapsules 48C.
It is about μm. On the other hand, as the wax type binder particles 54, paraffin wax having an average particle size of about 1 μm to about 3 μm at a heat melting temperature of 73 ° C. is used.

In short, the first microcapsule layer portion 46C is substantially the same as the first microcapsule layer portion 16C in the second embodiment, and the first microcapsule layer portion as shown in FIG. The stone wall structure of the layer portion 46C can also be formed in the same manner as the first microcapsule layer portion 16C.

Also in the first microcapsule layer portion 46C, when the binder particles 52 maintain the solid state, that is, the heating temperature for the first microcapsule layer portion 46C is the heat melting temperature of the binder particles 54 of 73 ° C. When described below, the first microcapsule layer portion 46C
Even if a pressure (with a shearing force) exceeding 2.0 MPa is applied, the pressure is supported by the solid-phase binder particles 52, so that the microcapsules 48C are not broken. However, when the heating temperature of the first microcapsule layer portion 46C becomes equal to or higher than the heat melting temperature of the binder particles 52 of 73 ° C., the binder particles 52 are thermally softened or melted. When the above pressure is applied, the microcapsules 48C are directly subjected to the breaking pressure and are broken. In addition,
The function of the spacer particles 54 included in the first microcapsule layer portion 46C is substantially the same as the function of the spacer particles 26 included in the first microcapsule layer portion 16C in the first embodiment described above. .

In short, as a final result, the first and second layers of the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40 are obtained.
The microcapsules 48C, 48M, and 48Y included in the microcapsule layer portions 46C and 46M / Y of FIG. 15 have temperature / pressure rupture characteristics as shown in the graph of FIG.

More specifically, as is clear from the graph of FIG. 15, the burst pressure characteristic curve PC of the wall film of the microcapsule 48C of the first microcapsule layer portion 46C,
Of the binder particles 54 included in the microcapsule layer portion 46C of the second embodiment and the thermal melting temperature 108 ° C. of the binder particles 50 included in the second microcapsule layer portion 46M / Y. When the temperature T ₁ and the pressure P ₃ included in the cyan coloring region C are applied to the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40, the microcapsules 4
Only 8C is destroyed and the cyan material is released.

As is clear from the graph of FIG. 15, the breaking pressure characteristic curve PC of the wall film of the microcapsule 48C of the first microcapsule layer portion 46C and the microcapsule curve of the second microcapsule layer portion 46M / Y. The burst pressure characteristic curve PM of the wall film of the capsule 48M and the binder particles 5 contained in the second microcapsule layer portion 46M / Y
The magenta coloring region (shaded region) M is defined by the heat melting temperature of 108 ° C. of 0 and the primary azeotropic point of the yellow coloring material of the microcapsules 48Y included in the second microcapsule layer portion 46M / Y at 150 ° C. When the temperature T ₂ and the pressure P ₂ included in the magenta coloring region M are applied to the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40, only the microcapsules 48M are destroyed and the magenta coloring material is released. Let me do.

Similarly, as is clear from the graph of FIG. 15, the breaking pressure characteristic curve PM of the wall film of the microcapsules 48M of the second microcapsule layer portion 46M and the second microcapsule layer portion 46M / Y The yellow-coloring region (hatched region) Y is defined by the primary azeotropic point of 150 ° C. of the yellow coloring material of the contained microcapsules 48Y,
The temperature T ₃ and the pressure P included in this yellow-colored area Y
_{When 1} is exerted on the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40, only the microcapsules 48Y are destroyed by the increase of the internal pressure, from which the yellow color material is released.

In short, by appropriately selecting the temperature and pressure to be exerted on the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40, the microcapsules 48C, 48M and 48Y contained in the microcapsule layer 44 are selectively destroyed. It is possible to do. In the third embodiment, each of the temperatures T ₁ , T ₂ and T ₃ is set to, for example, 90 ° C., 130 ° C. and 170 ° C., and each of the temperatures P ₁ , P ₂ and P ₃ is set. For example, 0.
01MPa, 1.0MPa and 3.0MPa can be set.

In the graph of FIG. 15, the reference symbol PY 'indicates the burst pressure characteristic of the microcapsule 48Y. As is apparent from the burst pressure characteristic PY', the wall film of the microcapsule 48Y has the microcapsule 48Y. 48Y is at least 3.0 MPa (P
₃ ) It must be able to withstand the above pressure.

Next, a description will be given of a coloring process when full-color coloring is performed on the pressure-sensitive thermosensitive recording medium 40.

The microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40 of the third embodiment shown in FIG.
However, in this case, the third roller platen 3 can be recorded by the third pressure applying spring means 34Y.
The pressing force when the 2Y is pressed against the third thermal head 30Y is set to a pressure P ₁ (0.01 MPa), and the fourth thermal head 30B and the fourth roller platen 3
2B and the fourth pressure applying means 34B are omitted.

When the pressure-sensitive thermosensitive recording medium 40 passes between the first thermal head 30C and the first roller platen 32C, the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40 includes a first pressure applying spring means. The heating elements _Rc1 , _Rc2 , _Rc3 ,... R of the first thermal head 30C for 34C.
_cn receives a pressure P ₃ (3.0 MPa) accompanied by a shearing force, and such a pressure P ₃ is applied to the microcapsule layer 4.
4 are not directly affected by the microcapsules 48C, 48M and 48Y because they are supported by the respective stone wall structures.

However, the first thermal head 30C
Heating element R_c1, R_c2, R_c3, ... R_cnEither is energized
When the heating element (R_c1, ... R_cn) Is the
Binder included in microcapsule layer portion 46C of No. 1
Temperature T higher than 73 ° C.₁(90 ℃)
Until the heating element (R_c1, ... R_cn)of
The binder particles 52 contained in the application area are thermally softened or thermally
The stone wall structure (the first micro
Is destroyed, and the heating element
Child (R_c1, ... R_cn) Is the first microphone as shown in FIG.
Microphone penetrates into the capsule layer part 46C and the microphone there
Pressure with shear force on the capsule 48C _Three(3.0MPa)
Exert. Thus, the pressure P_Three(3.0MPa) microphone
The capsule 48C is destroyed, and cyan material is released from it.
And a cyan dot is developed there.

When the pressure-sensitive thermosensitive recording medium 40 passes between the second thermal head 30M and the second roller platen 32M, the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40 is moved by the second pressure applying spring means. The heating elements _Rm1 , _Rm2 , _Rm3 ,... R of the second thermal head 30M for 34M.
_mn receives a pressure P ₂ (1.0 MPa) accompanied by a shearing force, and such a pressure P ₂ is applied to the microcapsule layer 44.
It is not directly affected by the microcapsules 48C, 48M and 48Y because it is supported by the respective stone wall structures therein.

However, when one of the heating elements R _m1 , R _m2 , R _m3 ,... R _mn of the second thermal head 30M is energized, the energized heating elements (R _{m1 ,.} First and second microcapsule layer portions 46C and 46M
/ Y is heated to a temperature T ₂ (130 ° C.) higher than the thermal melting temperatures (73 ° C. and 108 ° C.) of the binder particles 52 and 50 contained in the binder particles 52 and 50, so that the heating elements (R _m1 ,... R _mn ) are applied. The binder particles 52 and 50 included in the region are thermally softened or melted to break the stone wall structure in the application region, and at this time, the heating elements (R _m1 ,..., R _mn ) are in the first and second positions as shown in FIG. Second microcapsule layer portions 46C and 4
6M / Y penetrates and there microcapsules 48
C, 48M and 48Y have a pressure P ₂ with shear force (1.0MP
a). As described above, the microcapsules 48
Although C and 48Y can both withstand the pressure P ₂ (1.0 MPa), but the microcapsules 48M under pressure P ₂ (1.0 MPa) is destroyed and from there released magenta color material, there magenta The dots are colored.

When the pressure-sensitive thermosensitive recording medium 40 passes between the third thermal head 30Y and the third roller platen 32Y, the microcapsule layer 44 of the pressure-sensitive thermosensitive recording medium 40 is subjected to the third pressure application. the third heating element (R _y1, ... R _yn) of the thermal head 30Y for the spring means 34Y but will undergo pressure P ₁ with a shear force (0.01 MPa) from such pressure P ₁ micro It is not directly affected by the microcapsules 48C, 48M and 48Y because it is supported by the respective stone wall structure of the capsule layer 44.

However, when one of the heating elements (R _y1 ,... _Ryn ) of the third thermal head 30Y is energized,
The energized heating element is heated to the heat melting temperature (73 ° C., 108 ° C.) of the binder particles 52 and 54 contained in the first and second microcapsule layer portions 46C and 46M / Y, respectively.
° C.) of high addition microcapsule 48Y than yellow - temperature higher than the primary azeotropic point 0.99 ° C. colorants T ₃ (170
° C). Thus, the binder particles 52 and 50 contained in the application region of the heating element are thermally softened or thermally melted to break the stone wall structure in the application region. At this time, the heating element is first and second as shown in FIG. And the microcapsules 48C, 48M and 48Y penetrate the microcapsule layer portions 46C and 46M / Y
To a pressure P ₁ (0.01 MPa) accompanied by a shearing force. The microcapsules 48C and 48M have such a pressure P ₁ (0.
01 MPa), so that the microcapsules 48C and 48M are not destroyed. On the other hand, yellow in the microcapsule 48Y - color material is heated until the primary azeotropic point (approximately 0.99 ° C.) temperatures above T ₃ (170 ° C.), the internal pressure of the order the microcapsules 48Y is rapidly increased, thus micro Capsule 48Y has pressure P
_{Under 1} (0.01 MPa), the internal pressure is suddenly increased due to the rapid rise of the internal pressure, from which the yellow coloring material is released, and the yellow dot is developed there.

[0142] Also for the third embodiment described above,
It should be understood that various changes or modifications described for the second embodiment can be applied.

As in the case of the microcapsules 18BK of the second embodiment shown in FIG. 2, in the third embodiment,
Destruction of the microcapsules 48Y is largely dependent on the rapid increase in internal pressure, and even if the pressure P ₁ (0.01 MPa) is involved in the destruction, it is not an important factor in itself. In short, in the third embodiment, but is set to 0.01MPa Suitable values for the pressure P _1, while the sensitive pressure sensitive heat storage medium 40 of the third thermal head 30C and the third roller platen 32Y , The pressure-sensitive recording medium 40 can be reliably moved along the movement path 26 by the rotation of the third roller platen 32Y, and the heating elements (R _y1 ,... R) of the third thermal head 30Y. _yn ) against the pressure-sensitive thermosensitive recording medium 40
It is sufficient that the third roller platen 32Y is pressed against the third thermal head 30Y to such an extent that the microcapsule layer 44 can be pressed appropriately.

Referring to FIG. 18, a fourth embodiment of a pressure-sensitive thermosensitive recording medium according to the present invention is indicated generally by the reference numeral 60, wherein the pressure-sensitive thermosensitive recording medium 60 comprises a suitable support such as a sheet of paper 62. And a single microcapsule layer 64 applied to one surface of the sheet paper 62. As in the various embodiments described above, this single microcapsule layer 64 also has a stone wall structure, in which a number of microcapsules 66C containing a cyan coloring material and a number of magenta containing a magenta coloring material are provided. Capsules 66M, a number of yellow capsules 66Y enclosing the yellow color material, and a number of spacer particles 68 are uniformly distributed in the wax type binder particles 70. Microcapsule 6
6C is used to record a cyan image, microcapsules 66M are used to record a magenta image, and microcapsules 66Y are used to record a yellow image.
4, a full-color image can be recorded.

The microcapsules 66C are substantially the same as the microcapsules 18C in the second embodiment. That is, the wall film of the microcapsule 66C is the sheet paper 6
It is formed from an amino resin colored in the same color (usually white) as that of No. 2, and the cyan colorant enclosed therein is about 10% in KMC-113 (2,7 diisopropyl naphthalene) manufactured by Kureha Chemical Co.
% (Percent by weight) of a cyan dye such as phthalocyanine blue, and has an average particle size of about
The thickness is about 3 μm to about 4 μm, and the thickness of the wall film is such that the microcapsules 66C can be broken under a pressure of 2.0 MPa accompanied by a shearing force.

In the fourth embodiment, the microcapsules 6
6M has a double wall membrane structure as shown in FIG.
The inner wall film IS is formed of, for example, an amino resin, and the outer wall film OS has the same color as the sheet paper 62 (usually white).
It is formed from a suitable wax material which has been colored. For such a microcapsule 66M, for example, a suitable wax material, for example, microcrystalline wax having a melting point of 108 ° C. (CWP-3 manufactured by Seishin Enterprise Co., Ltd.) is applied to the outer wall surface of the microcapsule 18M used in the second embodiment.
By forming the outer wall film OS by a well-known spray drying method or a phase separation method. In short, the microcapsules 66M obtained by removing the outer wall film OS are the second microcapsules.
The inner wall film IS is substantially the same as the microcapsule 18M used in the embodiment of the present invention.
Is formed from an amino resin colored in the same color as that of (usually white), and the magenta coloring material enclosed in the resin is KMC-113 (2,7 diisopropylnaphthalene) manufactured by Kureha Chemical Co., Ltd. And the average particle size is also about 6 μm to about 7 μm.

In the fourth embodiment, when the microcapsule 66M is heated to a melting point of 108 ° C. or higher of the outer wall film OS, that is, when the outer wall film O of the microcapsule 66M is heated.
S is thermally melted, and the wall film of the microcapsule 66M is formed as shown in FIG.
As shown in FIG. 0, when only the inner wall film IS is formed, its temperature / pressure rupture characteristics are substantially the same as those of the microcapsules 18M in the above-described second embodiment. However, in a heating state in which the melting point of the outer wall film OS is lower than 108 ° C., that is, in a state where the outer wall film OS is in a solid phase, the microcapsules 66M have the outer wall film OS.
The microcapsule 6 is formed by the cooperation of the
It can withstand a pressure (with shearing force) far exceeding a breaking pressure of 2.0 MPa of 6 C.

The microcapsule 66Y has the same configuration as the microcapsule 48Y in the third embodiment. That is, the wall film of the microcapsule 66 is
Is formed from an amino resin colored in the same color as that of (usually white), and the yellow colorant enclosed therein has a primary azeotropic point of about
About 10% (weight percent) in a suitable clear oil at 150 ° C
And an average particle diameter of about 1 μm to about 3 μm. As in the case of the microcapsules 48Y in the third embodiment, as such a transparent oil, KMC-113 manufactured by Kureha Chemical Co., that is, 2,7 diisopropyl naphthalene (boiling point: about 300 ° C.) is mixed with 20 parts of n-heptane. %, And the one adjusted so that the primary azeotropic point is about 150 ° C. is used. Of course, as described above, in order to obtain a desired boiling point, xylene, benzene, naphthalene or the like having a boiling point lower than KMC-113 may be used instead of n-heptane. The thickness of the wall film of the microcapsule 66Y is such that it can withstand a pressure exceeding the breaking pressure of the microcapsule 66C exceeding 3.0 MPa at a primary azeotropic point of about 150 ° C. or less.

Also in the fourth embodiment, the spacer particles 68 are formed of hydroxyapatite, and the average particle size thereof is about 5 μm larger than the average particle size of the microcapsules 66C.
It is about m to 6 μm. The spacer particles 68
Is the same as the function of the spacer particles 26 used in the second embodiment.

On the other hand, the wax type binder particles 70
Is the first microcapsule layer portion 1 in the second embodiment.
It is substantially the same as the binder particles 28 used in 6C. That is, as the binder particles 70, the heat melting temperature
A paraffin wax at 73 ° C. is used, and such binder particles 28 are obtained by grinding such a paraffin wax material into particles having an average particle size of about 1 μm to about 3 μm by a jet mill.

Also in the fourth embodiment, the stone wall structure of the single microcapsule layer 64 can be obtained by a method substantially similar to that described above. (3) A 3% aqueous solution of polyvinyl alcohol (degree of polymerization: 2,000) is prepared, and 2.5 grams of spacer particles 68 and 5 grams of paraffin wax particles (binder particles 70) are added to 100 grams of this aqueous polyvinyl alcohol solution. A fixed amount (for example, 5 grams) of microcapsules 66C;
A predetermined amount (for example, 5 grams) of microcapsules 66M
And a predetermined amount (7.5 grams) of microcapsules 66Y
And a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) are mixed / stirred to prepare a suspension. ■ The above suspension on sheet paper 62 per square meter
Spray in an amount of 8 to 10 grams and allow to air dry once, then put it in a heating oven and heat melting temperature of paraffin wax particles (binder particles 70) (about 73 ° C)
To a slightly lower temperature of 68 ° C,
Maintained for 15 minutes, whereby the paraffin wax particles, i.e. the binder particles 70, are thermally fused to one another, thus obtaining a stone wall structure as schematically shown in FIG.

In the fourth embodiment, when the binder particles 70 are in the solid state, that is, the heating temperature of the single microcapsule layer 64 is set to the melting temperature of the binder particles 70 of 73 ° C. or less. In this case, even if a pressure (with shearing force) exceeding 2.0 MPa is applied to the single microcapsule layer 64 </ b> C, the pressure is supported by the solid-phase binder particles 70, so that the microcapsules 66 </ b> C are supported.
C, 66 and 66Y are not destroyed. However, when the heating temperature for the single microcapsule layer portion 64 is 73 ° C. or higher and the melting point of the outer wall film OS of the microcapsules 66M is less than about 108 ° C., the binder particles 70 are thermally softened or heat-treated. Since it is melted, when a pressure of 2.0 MPa or more accompanied by a shearing force is applied thereto, the breaking pressure of the microcapsules 66C, 66M
And 66Y will be received directly. However, microcapsules 66M (with outer wall membrane OS) and 66M
Since Y can withstand the burst pressure, the microcapsules 66
Only C will be destroyed.

The heating temperature of the single microcapsule layer portion 64 is changed to the outer wall film O of the microcapsule 66M.
When the melting point of S is about 108 ° C. or more and the primary azeotropic point of the yellow color material (the oil) of the microcapsules 66Y is less than about 150 ° C., not only the binder particles 70 but also the outer wall film OS of the microcapsules 66M is thermally softened or Since it is thermally melted, when a pressure of more than 0.2 MPa and a pressure of less than 2.0 MPa (with a shearing force) is applied thereto, the breaking pressure is directly received by the microcapsules 66C, 66M and 66Y. However, microcapsules 66C and 66C
Since Y can withstand the burst pressure, the microcapsules 66
Only M will be destroyed.

Further, when the heating temperature of the single microcapsule layer portion 64 is higher than the primary azeotropic point of the yellow color material (the oil) of the microcapsules 66Y at about 150 ° C. or more, the binder particles 70 also form the outer wall of the microcapsules 66M. The film OS is also thermally softened or thermally melted. However, if the pressure applied thereto is less than 0.2 MPa, the microcapsules 66C and 66M are not broken, and only the microcapsules 66Y are broken. . That is, when the heating temperature is higher than the primary azeotropic point (about 150 ° C.) of the yellow color material, the microcapsules 66Y are destroyed by themselves due to a sharp increase in the internal pressure, and the contents (yellow color material) are destroyed. )
Is released.

Thus, the microcapsules 66 included in the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60
For C, 66M and 66Y, the temperature / pressure rupture characteristics as shown in the graph of FIG. 21 are obtained. It should be noted that the temperature / pressure rupture characteristics themselves shown in the figure correspond to the microcapsules 48C, 48M and 48 in the third embodiment described above.
The temperature / pressure rupture characteristics of Y are substantially the same.

More specifically, as is clear from the graph of FIG. 21, the breakdown pressure characteristic curve PC of the wall film of the microcapsule 66C, the heat melting temperature of the binder particles 70 of 73 ° C., and the outer wall film OS of the microcapsule 66M. Heat melting temperature 108 ℃
Defines a cyan coloring region (hatched region) C. When the temperature T ₁ and the pressure P ₃ included in the cyan coloring region C are applied to the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60, There are microcapsules 66
Only C is destroyed and the cyan material is released.

As is clear from the graph of FIG. 21, the breaking pressure characteristic curve PC of the wall film of the microcapsule 66C and the breaking pressure of the inner wall film IS during the thermal melting of the outer wall film OS of the microcapsule 66M. A magenta coloring area (shaded area) M is defined by the characteristic curve PM, the melting point of the outer wall film OS of 108 ° C., and the primary azeotropic point of the yellow coloring material (oil) 150 ° C. of the microcapsules 66Y. When the temperature T ₂ and the pressure P ₂ contained in the coloring area M are applied to the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60, only the microcapsules 48M are destroyed, and the magenta coloring material is released. Can be

Similarly, as is clear from the graph of FIG. 21, the breakdown pressure characteristic curve PM of the inner wall film IS at a temperature higher than the heat melting temperature of the outer wall film OS of the microcapsule 66M and the yellow color of the microcapsule 66Y. The primary azeotropic point 150 ° C. of the material (oil) defines a yellow color-developing region (hatched region) Y. The temperature T ₃ and the pressure P ₁ contained in this yellow-color-developing region Y are determined by the pressure-sensitive thermosensitive recording medium 60. When applied to a single microcapsule layer 64, only the microcapsules 66Y are destroyed by their own rise in internal pressure, releasing the yellow colorant.

In short, by appropriately selecting the temperature and pressure to be applied to the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60, the single microcapsule layer 6
Microcapsules 66C, 66M and 66 contained in 4
Y can be selectively destroyed. The third
In the embodiment, each of the temperatures T ₁ , T ₂ and T ₃ is set to, for example, 90 ° C., 130 ° C. and 170 ° C.,
Further, each of the temperatures P ₁ , P ₂ and P ₃ can be set to, for example, 0.01 MPa, 1.0 MPa and 3.0 MPa.

In the graph of FIG. 21, reference numeral PY 'indicates a burst pressure characteristic of the microcapsule 66Y. As is apparent from the burst pressure characteristic PY', the wall film of the microcapsule 66Y has the microcapsule 66Y. At a temperature of 150 ° C. or less of the primary azeotropic point of the yellow color material, it can withstand a pressure of at least 3.0 MPa (P ₃ ).

Next, a description will be given of a coloring process when full-color coloring is performed on the pressure-sensitive thermosensitive recording medium 60.

A color image can also be recorded on the single microcapsule layer 64 of the pressure-sensitive and heat-sensitive recording medium 60 of the fourth embodiment shown in FIG. 18 by using an image recording apparatus as shown in FIGS. Possible, but in that case the third
The pressing force when the third roller platen 32Y is pressed against the third thermal head 30Y by the pressure applying spring means 34Y is set to a pressure P ₁ (0.01 MPa).
Further, the fourth thermal head 30B, the fourth roller platen 32B, and the fourth pressure applying means 34B are omitted.

When the pressure-sensitive thermosensitive recording medium 60 passes between the first thermal head 30C and the first roller platen 32C, the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60 is subjected to the first pressure application. First for spring means 34C
, R _c1 , R _c2 , R _c3 ,
... receives a pressure P ₃ (3.0 MPa) accompanied by a shearing force from R _cn , and the pressure P ₃ is supported in the microcapsule layer 44 by the binder layers each configured as a stone wall structure. 66C, 66M
And 66Y are not directly affected.

However, when one of the heating elements R _c1 , R _c2 , R _c3 ,... R _cn of the first thermal head 30C is energized, the energized heating elements (R _{c1 ,.} The binder particles 70 contained in the single microcapsule layer 64 are heated to a temperature T ₁ (90 ° C.) higher than the heat melting temperature 73 ° C., and are therefore included in the application area of the heating elements (R _c1 ,..., R _cn ). The binder particles 70 are thermally softened or melted to break the stone wall structure in the application area, and at this time, the heating elements (R _c1 ,..., R _cn ) enter the single microcapsule layer 64 as shown in FIG. And the pressure P with shear force applied to the microcapsules 66C, 66M and 66Y therein.
₃ (3.0MPa). As described above, under such temperature / pressure conditions, only the microcapsules 66C are destroyed, and the cyan coloring material is released therefrom, and cyan dots are developed there.

When the pressure-sensitive thermosensitive recording medium 60 passes between the second thermal head 30M and the second roller platen 32M, the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60 becomes the second microcapsule layer. For the pressure applying spring means 34M, the heat generating elements _Rm1 , _Rm2 ,
A pressure P ₂ (1.0 MPa) accompanied by a shearing force is received from R _m3 ,... R _mn , and the pressure P ₂ is supported by a binder layer configured as a stone wall structure in the single microcapsule layer 64. For microcapsules 66
It does not directly affect C, 66M and 66Y.

[0166] However, the heating elements of the second thermal head _{30M R m1, R m2, R} m3, ... When any of R _mn is energized, the energized heating element (R _m1, ... R _mn) is Melting point of binder particles 70 (73 ° C.) and microcapsules 6
A temperature T ₂ (1) higher than the melting point (108 ° C.) of the outer wall film of 6M.
30 ° C.), so that the heating elements (R _m1 ,...)
The binder particles 70 contained in the application region of R _mn ) are thermally softened or thermally melted to break the stone wall structure in the application region, and the outer wall film OS of the microcapsule 66M is also thermally softened or thermally melted. Heating element (R _m1 , ... R
_mn ) is a single microcapsule layer 64 as shown in FIG.
And the microcapsules 66C, 66 there
A pressure P ₃ (1.0 MPa) accompanied by a shear force is applied to M and 66Y. As described above, under such temperature / pressure conditions, only the microcapsules 66M are destroyed, and the yellow color material is released therefrom, and the magenta dots are colored there.

Similarly, when the pressure-sensitive thermosensitive recording medium 60 passes between the third thermal head 30Y and the third roller platen 32Y, the single microcapsule layer 64 of the pressure-sensitive thermosensitive recording medium 60 becomes the third microcapsule layer. Of the third thermal head 30Y (R _y1 ,... R
Although will receive the pressure P ₁ with a shear force (0.01 MPa) from _yn), the pressure P ₁ is a single microcapsule layer 6
4 does not directly affect the microcapsules 66C, 66M and 66Y to be supported by the respective stone wall structures.

[0168] However, the heating elements R _y1 of the third thermal head _{30Y, R y2, R y3,} ... When any of R _yn is energized, the energized heating elements (R _y1, ... R _yn) is Melting point of binder particles 70 (73 ° C.), microcapsules 66
M melting point (108 ° C.) of the outer wall film and microcapsules 6
The 6Y yellow colorant is heated to a temperature T ₃ (170 ° C.) higher than the primary azeotropic point (150 ° C.), so that the binder particles 70 contained in the application area of the heating element are softened or melted by heat. The heating element (R _y1 ,..., R _yn ) penetrates into the single microcapsule layer 64 as shown in FIG. 22 and shears into the microcapsules 66C, 66M and 66Y. A pressure P ₃ (0.01 MPa) accompanied by a force is applied. As described above, under such a temperature / pressure condition, only the microcapsules 66Y are destroyed by a sharp rise in their internal pressure, and yellow color materials are released from there, and yellow dots develop there. Let me do.

It should be understood that various changes or modifications described in the second and third embodiments can be applied to the fourth embodiment described above.

Microcapsules 66 in Fourth Embodiment
As a modified example of M, the outer wall film OS may be formed not only of a wax material but also of a material having an appropriate melting point, for example, ethyl P-hydroxybenzoate (melting point of 115 ° C. to 118 ° C.). Disperses the microcapsules 18M used in the above-described second embodiment in a solution of ethyl P-hydroxybenzoate to precipitate ethyl P-hydroxybenzoate on the surface of the microcapsules 18M to form the outer wall film OS. can do.

Further, in the fourth embodiment, the characteristics of the inner wall film IS and the outer wall film OS of the double-wall film structure of the microcapsule 66M can be reversed. That is, the inner wall film IS may be formed from the above-described wax material, and the outer wall film OS may be formed from an amino resin.

[0172]

As is apparent from the above description, in the pressure-sensitive thermosensitive recording medium according to the present invention, the microcapsule layer is selectively applied to the microcapsule layer by applying a predetermined temperature / pressure to the microcapsule layer. As the image recording can be performed by selectively destroying the microcapsules inside,
Unlike conventional recording media using photocurable microcapsules, there is no need to store individual pressure-sensitive and heat-sensitive recording media in a light-shielding package, etc., so the packaging material for packaging and storage is greatly reduced. Can be. Further, in the pressure-sensitive and heat-sensitive recording medium according to the present invention, since a color image can be recorded only by selecting the temperature / pressure, the conventional color image recording apparatus requires a light irradiation unit. It is possible not only to significantly reduce the size, but also to reduce the manufacturing cost. In the pressure-sensitive thermosensitive recording medium according to the present invention,
Even if a certain external force is inadvertently applied to the microcapsule layer, each microcapsule itself will not be easily broken. Performance will be greatly improved.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view schematically showing a part of a pressure-sensitive thermosensitive recording medium as a second embodiment of the recording medium according to the present invention.

FIG. 3 is an enlarged view of a third microcapsule layer of the three-layer microcapsule layer of the pressure-sensitive thermosensitive recording medium shown in FIG. 2;

FIG. 4 is an enlarged view of a second microcapsule layer portion of the three-layer structure microcapsule layer of the pressure-sensitive thermosensitive recording medium shown in FIG.

FIG. 5 is an enlarged view of a first microcapsule layer of the three-layered microcapsule layer of the pressure-sensitive thermosensitive recording medium shown in FIG. 2;

FIG. 6 is a graph showing temperature / pressure rupture characteristics of four types of microcapsules included in the first, second, and third microcapsule layer portions of the pressure-sensitive thermosensitive recording medium shown in FIG. 2;

FIG. 7 is a schematic sectional view showing an example of an image recording apparatus for performing full-color image recording on the pressure-sensitive thermosensitive recording medium of FIG.

FIG. 8 shows first, second, and third images included in the image recording device of FIG. 7;
And a control block diagram of a fourth thermal head.

9 is a schematic cross-sectional view schematically showing a state in which cyan dots are formed on the first microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. 2 by the heating elements of the first thermal head of the image recording apparatus of FIG. FIG.

10 is a schematic cross-sectional view schematically showing a state in which a magenta dot is colored on a second microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. 2 by a heating element of a second thermal head of the image recording apparatus of FIG. FIG.

11 is a heating element of a third thermal head or a heating element of a fourth thermal head of the image recording apparatus of FIG. 7; FIG. 3 is a schematic cross-sectional view schematically showing a state in which black dots are colored.

FIG. 12 is a schematic sectional view schematically showing a part of a pressure-sensitive and heat-sensitive recording medium as a third embodiment of the recording medium according to the present invention.

13 is an enlarged view of a second microcapsule layer portion of the double-layered microcapsule layer of the pressure-sensitive thermosensitive recording medium shown in FIG.

14 is an enlarged view of a first microcapsule layer portion of the double-layered microcapsule layer of the pressure-sensitive thermosensitive recording medium shown in FIG.

FIG. 15 is a graph showing temperature / pressure rupture characteristics of three types of microcapsules included in the first and second microcapsule layer portions of the pressure-sensitive thermosensitive recording medium shown in FIG.

FIG. 16 is a schematic cross-sectional view schematically showing a state in which cyan dots are formed on the first microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. 12 by the heating elements of the first thermal head of the image recording apparatus of FIG. FIG.

FIG. 17 shows a heating element of the second thermal head or a heating element of the third thermal head of the image recording apparatus of FIG. 7, which is used to form a magenta dot or yellow dot on the second microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. FIG. 3 is a schematic cross-sectional view schematically showing a state in which dots are colored.

FIG. 18 is a schematic sectional view schematically showing a part of a pressure-sensitive thermosensitive recording medium as a fourth embodiment of the recording medium according to the present invention.

19 is an enlarged cross-sectional view schematically showing a microcapsule having a double wall film structure included in a single microcapsule layer of the pressure-sensitive thermosensitive recording medium shown in FIG.

20 is an enlarged cross-sectional view showing the microcapsule in a state where the outer wall film of the microcapsule having the double-wall film structure shown in FIG. 19 is thermally melted.

FIG. 21 is a graph showing temperature / pressure rupture characteristics of three types of microcapsules included in a single microcapsule of the pressure-sensitive thermosensitive recording medium shown in FIG.

FIG. 22 shows a heating element of any of the first, second and third thermal heads of the image recording apparatus of FIG. 7 for forming cyan dots on a single microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. 18;
FIG. 3 is a schematic cross-sectional view schematically showing a state in which one of a magenta dot and a yellow dot is colored.

[Explanation of symbols]

 2 Thermal recording medium 4.12 Support (sheet paper) 6.14 Microcapsule layer 8 Thermal microcapsule 10 Pressure sensitive thermal recording medium 16C First microcapsule layer portion 16M Second microcapsule layer portion 16Y / B Third Microcapsule layer part of 18C ・ 18M ・ 18Y ・ 18BK Microcapsule

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Shinbo Asahi Gaku Kogyo Co., Ltd. 2-36-9 Maeno-cho, Itabashi-ku, Tokyo (72) Inventor Hiroshi Inogari 6-7-1 Nakaokacho, Iwaki-shi, Fukushima Prefecture F-term (reference) 2H026 AA07 AA28 BB02 BB21 CC05 DD01 DD32 DD36 DD45 DD48 DD53 FF05 FF07 FF24 2H085 AA07 AA11 AA13 BB02 BB21 CC00 CD01 CD17 DD23 DD32 DD48 FE02 2H111 AA14 AA33 BAABA BA23 BA48

Claims (61)

[Claims] 1. A heat-sensitive microcapsule comprising a liquid coloring material having a predetermined boiling point and a wall film enclosing the liquid coloring material, wherein the wall film is destroyed by its internal pressure rise under a heating state above the boiling point. A heat-sensitive microcapsule characterized by having a temperature destruction property of releasing a liquid coloring material. 2. The heat-sensitive microcapsule according to claim 1, wherein the liquid coloring material comprises a liquid vehicle and a pigment dispersed or dissolved in the liquid vehicle. 3. The heat-sensitive microcapsule according to claim 2, wherein the liquid vehicle is made of a transparent oil. 4. The heat-sensitive microcapsule according to claim 3, wherein the transparent oil comprises at least a high-boiling oil. 5. The heat-sensitive microcapsule according to claim 4, wherein the high-boiling oil comprises at least two oil components having different boiling points to obtain a desired boiling point. 6. The heat-sensitive microcapsule according to claim 1, wherein the wall film is formed of a thermosetting resin. 7. The heat-sensitive microcapsule according to claim 1, wherein the wall film is formed of a high melting point thermoplastic resin. 8. A thermosensitive recording medium comprising a support and a microcapsule layer applied to the surface of the support, wherein the microcapsule layer is formed from heat-sensitive microcapsules, and the heat-sensitive microcapsules have a predetermined boiling point. And a wall film enclosing the liquid color material,
A heat-sensitive recording medium, characterized in that the wall film has a temperature destruction property such that the wall film is destroyed by an increase in its internal pressure under a heating state higher than the boiling point and releases the liquid color material. 9. The heat-sensitive recording medium according to claim 8, wherein the liquid coloring material comprises a liquid vehicle and a dye dispersed or dissolved in the liquid vehicle. 10. The heat-sensitive recording medium according to claim 9, wherein the liquid vehicle is made of a transparent oil. 11. The heat-sensitive recording medium according to claim 10, wherein said transparent oil comprises a high-boiling oil. 12. The heat-sensitive recording medium according to claim 11, wherein the high-boiling oil comprises at least two oil components having different boiling points to obtain a desired boiling point. 13. The thermosensitive recording medium according to claim 8, wherein the wall film is formed of a thermosetting resin. 14. The heat-sensitive recording medium according to claim 8, wherein the wall film is formed of a high melting point thermoplastic resin. 15. A pressure-sensitive thermosensitive recording medium comprising a support and a microcapsule layer applied to the surface of the support, wherein the microcapsule layer is a first, a second, and a third microcapsule layer. Wherein the third microcapsule layer portion is formed on the surface of the support, the second microcapsule layer portion is formed on the third microcapsule layer portion, and the first microcapsule layer portion is formed on the first microcapsule layer portion. A microcapsule layer portion formed on the second microcapsule layer portion, wherein the first microcapsule layer portion comprises a plurality of first microcapsules evenly distributed in a first binder material; Each of the first microcapsules has a first colorant encapsulated therein, and the second microcapsule layer portion has a plurality of second microcapsule layers uniformly distributed in a second binder material. A second coloring material is encapsulated in each of the second microcapsules, and the third microcapsule layer portion is uniformly distributed in a third binder material. A pressure-sensitive thermosensitive element comprising a third coloring material and a third coloring material, wherein each of the third microcapsules is filled with a third coloring material, and the fourth microcapsule is filled with a fourth coloring material. In the recording medium, the first binder material has a first heat melting temperature, and the first microcapsules in the first microcapsule layer portion are in a heat-softened state or a heat-melted state of the first binder material. The second binder material has a second heat melting temperature higher than the first heat melting temperature; No. in the microcapsule layer The microcapsules in the heat softened state or under hot-melt conditions of the second binder material of the first
The third binder material has a third heat melting temperature higher than the second heat melting temperature, and has a pressure rupture property that is broken under a second pressure lower than the pressure of The third microcapsule in the microcapsule layer portion of the third binder material is the second microcapsule in the heat softened state or the molten state of the third binder material.
The third coloring material has a boiling point higher than a third heat melting temperature of the third binder material, the fourth coloring material having a pressure rupture property of being broken under a third pressure lower than the pressure of A pressure-sensitive thermosensitive recording medium characterized in that the fourth microcapsule has a temperature destruction property such that the fourth microcapsule is destroyed by itself at least under the heating state of the boiling point of the fourth color material and releases the fourth color material. . 16. The pressure-sensitive thermosensitive recording medium according to claim 15, wherein the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules. A pressure-sensitive thermosensitive recording medium, wherein the average particle size is smaller than the third average particle size. 17. The pressure-sensitive and heat-sensitive recording medium according to claim 16, wherein a first spacer particle larger than an average particle diameter of the first microcapsule is uniformly formed in the first microcapsule layer portion. Wherein the second spacer particles larger than the average particle size of the second microcapsules are uniformly distributed in the second microcapsule layer portion. 18. The pressure-sensitive thermosensitive recording medium according to claim 17, wherein the first and second spacer particles are formed of an inorganic material. 19. The pressure-sensitive thermosensitive recording medium according to claim 17, wherein said first and second spacer particles are formed of a high melting point synthetic resin material. 20. Any one of claims 15 to 19
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And the third binder material are formed as binder particles fused to each other, whereby each of the first, second and third microcapsule layer portions is formed as a stone wall structure. Pressure sensitive thermosensitive recording medium. 21. Any one of claims 15 to 20
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third coloring material comprising a vehicle and a dye dispersed or dissolved in the vehicle. 22. The pressure-sensitive thermosensitive recording medium according to claim 21, wherein a leuco dye is used as the dye, and each of the first, second and third binder materials is a developer of the leuco dye. And a pressure-sensitive and heat-sensitive recording medium. 23. Any one of claims 15 to 22.
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third color material comprising three primary colors. 24. Any one of claims 15 to 23
Item 4. The pressure-sensitive thermosensitive recording medium according to Item 1, wherein the average particle size of the fourth microcapsules is smaller than the average particle size of the first, second, and third microcapsules. Medium. 25. Any one of claims 15 to 24
Item 4. The pressure-sensitive heat-sensitive recording medium according to Item 1, wherein the fourth colorant comprises a liquid vehicle and a dye dispersed or dissolved in the liquid vehicle. 26. The pressure-sensitive thermosensitive recording medium according to claim 25, wherein the liquid vehicle contains at least a substance for adjusting a boiling point of the liquid vehicle. 27. The pressure-sensitive thermosensitive recording medium according to claim 25, wherein a leuco dye is used as the dye, and the third binder material contains a developer of the leuco dye. Pressure and heat sensitive recording medium. 28. Any one of claims 15 to 27
4. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein the fourth color material is black. 29. A pressure-sensitive thermosensitive recording medium comprising a support and a microcapsule layer applied to the surface of the support, wherein the microcapsule layer comprises first and second microcapsule layer portions. The second microcapsule layer portion is formed on the surface of the support, the first microcapsule layer portion is formed on the second microcapsule layer portion, and the first microcapsule layer is formed. A portion comprising a plurality of first microcapsules uniformly distributed in a first binder material, wherein each of the first microcapsules is encapsulated with a first colorant; The layer portion comprises a number of second and third microcapsules evenly distributed in a second binder material, each of the second microcapsules having a second colorant. A pressure-sensitive thermosensitive recording medium in which a third coloring material is encapsulated in each of the third microcapsules, wherein the first binder material has a first heat melting temperature; Wherein the first microcapsules in the microcapsule layer portion of the second binder have a pressure rupture property of being broken under a first pressure in a heat-softened state or a heat-melted state of the first binder material; The material has a second heat melting temperature higher than the first heat melting temperature, and the second microcapsules in the second microcapsule layer portion are in a heat-softened state or a heat-softened state of the second binder material. The first in a molten state
Having a pressure rupture property to be broken under a second pressure lower than the pressure of the third microcapsule, the third coloring material encapsulated in each of the third microcapsules is formed by a second heat of the second binder material. Having a boiling point higher than the melting temperature, and having a temperature destruction characteristic such that the third microcapsules are destroyed by themselves under at least the heating state of the boiling point of the third coloring material. Pressure sensitive recording medium. 30. The pressure-sensitive thermosensitive recording medium according to claim 29, wherein the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules, and the average size of the third microcapsules. A pressure-sensitive thermosensitive recording medium characterized in that the particle size is smaller than the first and second average particle sizes. 31. The pressure-sensitive thermosensitive recording medium according to claim 29, wherein spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the first microcapsule layer portion. Pressure-sensitive heat-sensitive recording medium characterized by being capable of being used. 32. The pressure-sensitive thermosensitive recording medium according to claim 31, wherein the spacer particles are formed of an inorganic material. 33. The pressure-sensitive thermosensitive recording medium according to claim 31, wherein the spacer particles are formed of a high melting point synthetic resin material. 34. Any one of claims 29 to 33
3. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein each of the first and second binder materials is formed as binder particles fused to each other, so that the first and second microcapsule layer portions are respectively made of stone walls. A pressure-sensitive thermosensitive recording medium characterized by being formed as a structure. 35. Any one of claims 29 to 34
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third coloring material comprising a vehicle and a dye dispersed or dissolved in the vehicle. 36. The pressure-sensitive thermosensitive recording medium according to claim 35, wherein the vehicle of the third color material is a liquid. 37. The pressure-sensitive thermosensitive recording medium according to claim 36, wherein the liquid vehicle contains at least a substance for adjusting a boiling point of the liquid vehicle. 38. Any one of claims 35 to 37
3. The pressure-sensitive recording medium according to claim 1, wherein a leuco dye is used as the dye, and each of the first and second binder materials contains a developer of the leuco dye. Thermal recording medium. 39. Any one of claims 29 to 38
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third color material comprising three primary colors. 40. A pressure-sensitive thermosensitive recording medium comprising a support and a microcapsule layer applied to the surface of the support, wherein the microcapsule layer is composed of a plurality of microcapsule layers uniformly distributed in a binder material. The first microcapsule includes a first colorant encapsulated in each of the first microcapsules, and a second color capsule includes a second color capsule in each of the second microcapsules.
Wherein the binder material has a predetermined heat melting temperature, and
Has a pressure rupture property in which the microcapsules are broken under a first pressure at a first temperature higher than a heat melting temperature of the binder material in a heat softening state or a heat melting state of the binder material, The second coloring material encapsulated in each of the second microcapsules has a boiling point higher than the first temperature, and
Wherein the microcapsules have a temperature destruction property such that they are destroyed at least by heating at the boiling point of the second colorant. 41. The pressure-sensitive thermosensitive recording medium according to claim 40, wherein the average particle size of the second microcapsules is smaller than the average particle size of the first microcapsules. Medium. 42. The pressure-sensitive thermosensitive recording medium according to claim 40, wherein spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the microcapsule layer. Pressure and heat sensitive recording medium. 43. A pressure-sensitive thermosensitive recording medium according to claim 42, wherein said spacer particles are formed of an inorganic material. 44. The pressure-sensitive thermosensitive recording medium according to claim 42, wherein said spacer particles are formed of a high melting point synthetic resin material. 45. Any one of claims 40 to 44
4. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein the binder material is formed as binder particles fused to each other, whereby the microcapsule layer is formed as a stone wall structure. 46. Any one of claims 40 to 45
Item 4. The pressure-sensitive heat-sensitive recording medium according to Item 1, wherein each of the first and second coloring materials comprises a vehicle and a dye dispersed or dissolved in the vehicle. 47. The pressure-sensitive thermosensitive recording medium according to claim 46, wherein the vehicle of the second color material is a liquid. 48. The pressure-sensitive thermosensitive recording medium according to claim 47, wherein the liquid vehicle contains at least a substance for adjusting the boiling point of the liquid vehicle. 49. Any one of claims 46 to 48
The pressure-sensitive heat-sensitive recording medium according to item 1, wherein a leuco dye is used as the dye, and the binder material contains a developer of the leuco dye. 50. A pressure-sensitive thermosensitive recording medium comprising a support and a microcapsule layer applied to the surface of the support, wherein the microcapsule layer is composed of a plurality of microcapsule layers uniformly distributed in a binder material. A first, a second and a third microcapsule, each of the first microcapsules having a first microcapsule;
Pressure-sensitive thermosensitive recording, wherein each of the second microcapsules has a second colorant encapsulated therein, and each of the third microcapsules has a third colorant encapsulated therein. The medium, wherein the binder material has a predetermined heat melting temperature,
Has a pressure rupture property in which the microcapsules are broken under a first pressure at a first temperature higher than a heat melting temperature of the binder material in a heat softening state or a heat melting state of the binder material, The second microcapsules are broken under a heat softening state or a heat melting state of the binder material and under a second pressure lower than the first pressure at a second temperature higher than the first temperature. The third colorant encapsulated in each of the third microcapsules has a boiling point higher than the second temperature, and the third colorant has a boiling point higher than the second temperature.
Pressure-sensitive recording medium characterized in that the microcapsules have a temperature-destructive property such that they are destroyed by themselves under at least the heating state of the boiling point of the third colorant. 51. The pressure-sensitive thermosensitive recording medium according to claim 50, wherein the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules, and the average size of the third microcapsules. A pressure-sensitive thermosensitive recording medium characterized in that the particle size is smaller than the first and second average particle sizes. 52. The pressure-sensitive thermosensitive recording medium according to claim 50, wherein the second microcapsule has a double-walled film structure, and one of an inner wall film and an outer wall film is formed of the second microcapsule. 2. A pressure-sensitive heat-sensitive recording medium having a property of melting or softening at a temperature of 2. 53. Any one of claims 50 to 52
Item 4. The pressure-sensitive heat-sensitive recording medium according to Item 1, wherein spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the microcapsule layer. 54. The pressure-sensitive thermosensitive recording medium according to claim 53, wherein the spacer particles are formed of an inorganic material. 55. A pressure-sensitive thermosensitive recording medium according to claim 53, wherein said spacer particles are formed from a high melting point synthetic resin material. 56. Any one of claims 50 to 55
4. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein the binder material is formed as binder particles fused to each other, whereby the microcapsule layer is formed as a stone wall structure. 57. Any one of claims 50 to 56
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third coloring material comprising a vehicle and a dye dispersed or dissolved in the vehicle. 58. The pressure-sensitive thermosensitive recording medium according to claim 57, wherein the vehicle of the third color material is a liquid. 59. The pressure-sensitive thermosensitive recording medium according to claim 58, wherein the liquid vehicle contains at least a substance for adjusting a boiling point of the liquid vehicle. 60. Any one of claims 57 to 59
The pressure-sensitive heat-sensitive recording medium according to item 1, wherein a leuco dye is used as the dye, and the binder material contains a developer of the leuco dye. 61. Any one of claims 50 to 60
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third color material comprising three primary colors.