JP2001162943A - Pressure-sensitive thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new pressure-sensitive thermal recording medium which has a microcapsule layer containing a plurality of microcapsules sealing a coloring material and does not substantially produce waste during using the medium and further, easily records an image in the microcapsule layer at a low cost. SOLUTION: This pressure-sensitive thermal recording medium 10 is formed of a sheet 12 and a microcapsule layer 14 applied to the surface of the sheet 12. The microcapsule layer is made up of a plurality of microcapsules 18C, 18M, 18Y uniformly distributed in binder materials 28, 24, 20, each of, the microcapsules 18C, 18M, 18Y sealing the coloring material The binder materials 28, 24, 20 have a specified heat melt temperature and the microcapsules 18C, 18M, 18Y show such pressure breaking properties that they break under a specified pressure in the hot melt state of the binder materials 28, 24, 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium having a microcapsule layer including a number of microcapsules enclosing a coloring material, wherein the recording medium selectively destroys the microcapsules, and The present invention relates to a recording medium that forms an image on the microcapsule layer by releasing a coloring material to form a color.

[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 broken,
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]

In the former recording medium, when the microcapsule layer of the recording medium before use is exposed to light, the wall film of the microcapsule is hardened. Images must be stored in a light-shielded state, and image recording on this type of recording medium must be performed in a light-shielded environment. Also, unexposed microcapsules (ie, uncured microcapsules) are easily broken,
When handling a recording medium, care must be taken to prevent careless external force from being 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, an object of the present invention is to provide a recording medium having a microcapsule layer including a large number of microcapsules enclosing a coloring material, and the use of the recording medium involves substantially no waste. In addition, it is an object of the present invention to provide a novel recording medium which is not only easy to handle but also can record an image on the microcapsule layer at low cost and easily.

[0008]

According to a first aspect of the present invention, a thermosensitive recording medium comprises a support, and a microcapsule layer applied to the surface of the support. The layer consists of a number of microcapsules evenly distributed in the binder material, each of which encapsulates a colorant. In such a pressure-sensitive thermosensitive recording medium, the binder material has a predetermined heat melting temperature, and the microcapsules in the microcapsule layer are broken under a predetermined pressure under the heat softening state or the heat melting state of the binder material. It is characterized by having pressure rupture characteristics.

The binder material may comprise a wax material having a melting point substantially corresponding to the above-mentioned predetermined heat melting temperature or a low melting point thermoplastic resin material. Preferably, the binder material is formed as binder particles fused together,
At this time, the microcapsule layer has a stone wall structure.

[0010] The colorant may comprise a vehicle and a pigment dispersed or dissolved in the vehicle. Preferably, a leuco dye is used as the pigment, and a developer for the leuco dye is contained in the microcapsule layer.

The wall film of the microcapsule can be formed from a heat-resistant synthetic resin material. Such a heat-resistant synthetic resin material may be a thermosetting resin or a high melting point thermoplastic resin.

According to a second aspect of the present invention, a pressure-sensitive and heat-sensitive recording medium comprises a support and a microcapsule layer applied to the surface of the support. 2 and a third microcapsule layer portion, wherein the third microcapsule layer portion is first formed on the surface of the support, and then the second microcapsule layer portion is formed on the third microcapsule layer portion. Then, the first microcapsule layer portion is formed on the second microcapsule layer portion. The first microcapsule layer portion is composed of a number of first microcapsules uniformly distributed in a first binder material, each of the first microcapsules being encapsulated with a first coloring material, The second microcapsule layer portion is composed of a number of second microcapsules evenly distributed in the second binder material, and each of the second microcapsules is encapsulated with a second colorant, The third microcapsule layer portion comprises a number of third microcapsules evenly distributed in the third binder material, each of which encapsulates a third colorant. . 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. Alternatively, the second binder material has a pressure rupture property of being ruptured under a first pressure in a hot-melt state, and
Having a second heat melting temperature higher than the heat melting temperature of
The second microcapsule in the microcapsule layer portion has a pressure rupture property in which the second microcapsule is broken 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 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 in a thermally softened state of the third binder material. Alternatively, it is characterized by having a pressure rupture property of being broken under a third pressure lower than the second pressure in a hot-melt state.

In a preferred embodiment according to the second aspect of the present invention, the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules, and the average particle size of the second microcapsules is It is made smaller than the third average particle size. Preferably, first spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the first microcapsule layer portion, and the second microcapsule layers are provided in the second microcapsule layer portion. Are uniformly distributed, and the first and second spacer particles can be formed of an inorganic material or a high melting point synthetic resin material.

As in the first aspect of the present invention, in the second aspect of the present invention, each of the first, second and third binder materials is made of a wax material or a low melting point thermoplastic resin material. Preferably, the binder particles are fused together, with each of the first, second and third microcapsule layer portions being formed as a stone wall structure.

[0015] Also, like the first aspect of the present invention, in the second aspect of the present invention, each of the first, second and third color materials is dispersed in a vehicle and dispersed or dissolved in the vehicle. And a dye. Preferably, a leuco dye is used as each dye, and each of the first, second and third microcapsule layer portions contains a developer of the respective leuco dye. The first, second, and third color materials constitute, for example, three primary colors of cyan, magenta, and yellow.

According to a third aspect of the present invention, a pressure-sensitive thermosensitive recording medium comprises a support, a thermosensitive coloring layer applied to the surface of the support, and a microcapsule applied to the thermosensitive coloring layer. A microcapsule layer comprising first and second microcapsule layer portions, wherein the second microcapsule layer portion is formed on the surface of the thermosensitive coloring layer,
The first microcapsule layer portion is formed on the second microcapsule layer portion. The first microcapsule layer portion is composed of a number of first microcapsules uniformly distributed in a first binder material, each of the first microcapsules being encapsulated 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. . 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. Alternatively, the second binder material has a second heat melting temperature higher than the first heat melting temperature, and has a second pressure lowering property. A second microcapsule in the microcapsule layer portion has a pressure rupture property that is ruptured under a second pressure lower than the first pressure under a heat-softened state or a hot-melt state of the second binder material; The thermosensitive coloring layer is characterized in that the thermosensitive coloring layer develops a color different from the respective colors of the first and second coloring materials at a temperature higher than the second heat melting temperature of the second binder material.

In a preferred embodiment according to the third aspect of the present invention, the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules. Preferably, spacer particles larger than the average particle size of the first microcapsules are uniformly distributed in the first microcapsule layer portion, and these spacer particles can be formed from an inorganic material or a high melting point synthetic resin material.

As in the first and second aspects of the present invention, in the third aspect of the present invention, each of the first and second binder materials is made of a wax material or a low melting point thermoplastic resin material. Preferably, the binder particles are fused together,
At this time, each of the first and second microcapsule layer portions is formed as a stone wall structure.

Also, as in the first and second aspects of the present invention, in the third aspect of the present invention, each of the first and second color materials is dispersed in a vehicle and dispersed or dissolved in the vehicle. And a dye. Preferably, a leuco dye is used as each pigment, and each of the first and second microcapsule layer portions contains a developer of the respective leuco dye. The first and second color materials constitute two of the three primary colors, for example, cyan and magenta, and the color developed by the thermosensitive coloring layer constitutes the remaining of the three primary colors, for example, yellow.

[0020]

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

Referring first to FIG. 1, a first embodiment of a pressure-sensitive thermosensitive recording medium according to the present invention is indicated generally by the reference numeral 10, wherein the pressure-sensitive thermosensitive recording medium 10 comprises a suitable support such as a sheet. It comprises paper 12 and 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 includes a first microcapsule layer portion 16C for recording a cyan image and a second microcapsule layer portion 16M for recording a magenta image.
And a third microcapsule layer portion 16Y for recording a yellow image. The third microcapsule layer portion 16Y is first formed on the surface of the sheet paper 12,
Next, a second microcapsule layer portion 16M is formed on the third microcapsule layer portion 16Y, followed by the first microcapsule layer portion 16Y.
Is formed on the second microcapsule layer portion 16M.

As schematically shown in FIGS. 1 and 2, the third
The microcapsule layer portion 16Y has a stone wall structure, in which a number of microcapsules 18Y enclosing a yellow color material are uniformly distributed in the wax type binder particles 20.

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 this 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 be produced by a known microcapsule manufacturing method, for example, Japanese Patent Application Laid-Open No. 58-33492 and
The interfacial polymerization method disclosed in JP-A-58-82785 and i.
It can be produced by an n situ polymerization method or the like, and its average particle size is about 9 μm to 10 μm,
Regarding the thickness of the wall film, the microcapsule 18Y
Can be broken under a pressure of 0.02 MPa or more with shear force.

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.

The stone wall structure of the third microcapsule layer portion 16Y can be obtained by the following method. That is, (1) polyvinyl alcohol (polymerization degree 2,000)
% Of an aqueous adhesive solution, 100 grams of this adhesive aqueous solution, 10 grams of PPW-5 (polypropylene wax powder), an appropriate amount, for example, 10 grams of microcapsules 18Y, and a small amount of a dispersant (dodecylbenzene) Sodium sulfonate) to prepare a suspension. (2) The suspension is sprayed onto sheet paper 12 in an amount of 3 to 5 grams per square meter, air-dried once, and then placed in a heating oven to heat the PPW-5 to a heat melting temperature (about 150 ° C.). Is heated to a temperature somewhat lower than 145 ° C., and the heating is maintained for about 15 minutes, whereby the PPW-5 (polypropylene wax powder), ie, the binder particles 20, are thermally fused to one another, thus A stone wall structure as shown in FIG. 2 is obtained. In addition, such a heat treatment is a treatment for increasing the strength of the stone wall structure,
If the strength of the stone wall structure is sufficient with the adhesive strength obtained with an aqueous solution of polyvinyl alcohol or another aqueous solution of an adhesive, the heat treatment can be omitted.

According to the above-described method, the binder particles 20 themselves are not melted by heat, so that a fine gap is left between the binder particles and the microcapsules 18Y, and the specific gravity of the microcapsules 18Y. Is larger than the specific gravity of the binder particles 20, so that the microcapsules 18
Y sinks below the third microcapsule layer portion 16 </ b> Y and becomes covered with the binder particles 20.

In the third microcapsule layer portion 16Y, when the binder particles 20 are in a solid state, that is, the heating temperature of the third microcapsule layer portion 16Y is not higher than the thermal melting temperature of the binder particles 20 of 150 ° C. The third microcapsule layer portion 16Y
Even if a breaking pressure of 0.02 MPa or more due to shearing force is applied to the microcapsules 18Y, the breaking pressure is not hindered by the stone wall structure of the binder particles 20, and does not directly reach the microcapsules 18Y. It is not. However, the heating temperature for the third microcapsule layer portion 16Y is lower than the binder particles 20.
When the heat melting temperature of the binder becomes 150 ° C. or more, the binder particles 2
Since 0 is heat-melted, when a pressure of 0.02 MPa or more accompanied by a shearing force is applied thereto, the microcapsule 18Y is directly subjected to the breaking pressure and is broken.

As schematically shown in FIGS. 1 and 3, 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 microcapsule 18Y,
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,
The magenta coloring material enclosed there is about
It contains 10% (weight percent) of magenta dye. As the transparent oil, Kureha Chemical Co.
KMC-113 (2,7 diisopropyl naphthalene) is used, and Rhodamine Lake T or the like is used as a magenta dye. Such a microcapsule 18M is also manufactured by the above-mentioned well-known microcapsule manufacturing method such as an interfacial polymerization method or
It can be produced by a situ polymerization method or the like, and its average particle size is about 6 μm to 7 μm,
The thickness of the wall film is such that the microcapsules 18M can be broken under a pressure of 0.2 MPa or more accompanied by a shearing force. In the present embodiment, the spacer particles 22
Hydroxyapatite is used, and its average particle size is about 8 μm to 9 μm, which is larger than the average particle size of the microcapsules 18M.

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), its average particle size is about 3-5 μm, and its hot melt temperature is about 108 ° C. The binder particles 24, that is, the 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. That is, (1) polyvinyl alcohol (polymerization degree 2,000
) Is prepared, and 100 g of the adhesive aqueous solution is added to 5 g of the spacer particles 22, 10 g of CWP-3 (microcrystalline wax powder), and an appropriate amount of, for example, 10 g. Micro capsule 1
8M and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) are mixed / stirred to prepare a suspension.
(2) The suspension is sprayed on the third microcapsule layer portion 16Y in an amount of 2 to 4 grams per square meter and air-dried once, and then placed in a heating oven to thermally melt CWP-3. Heat to a temperature of 103.degree. C., somewhat lower than the temperature (about 108.degree. C.), and maintain the heating state for about 15 minutes, so that CWP-3 (microcrystalline wax powder), or binder particles 24, heats each other. It is 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.

As in the case of the third microcapsule layer portion 16Y, also in the second microcapsule layer portion 16M, when the binder particles 24 maintain a solid state, that is, in the second microcapsule layer portion. When the heating temperature with respect to 16M is equal to or lower than the thermal melting temperature of the binder particles 24 of 108 ° C., even if a burst pressure of 0.2 MPa or more accompanied by a shearing force is applied to the second microcapsule layer portion 16M, the burst pressure is maintained at the binder particle The microcapsules 18M are not directly hindered by the 24 stone wall structures and do not break down. However, the second microcapsule layer portion 16
The heating temperature with respect to M is the thermal melting temperature of the binder particles 24 of 10
When the temperature reaches 8 ° C. or higher, the binder particles 24 are melted by heat. When a pressure of 0.2 MPa or more accompanied by a shearing force is applied to the binder particles 24, the microcapsules 18 </ b> M are directly subjected to the breaking pressure and are broken. You. 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. 1 and 4, 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.

As in the case of the microcapsules 18Y and 18M, the wall film of the microcapsules 18C is also made of the sheet paper 1.
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 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. Of course, such a microcapsule 1
8C can also be produced by a well-known microcapsule production method as described above, for example, an interfacial polymerization method or an in situ polymerization method, and has an average particle size of about 3 μm or less.
The thickness of the wall film is such that the microcapsules 18C can be broken under a pressure of 2.0 MPa or more accompanied by a shearing force. Further, as in the case of the spacer particles 22 described above, the spacer particles 26 include:
Hydroxyapatite is used, and its average particle size is about 5 μm, which is larger than the average particle size of the microcapsules 18C.
Or about 6 μm.

On the other hand, 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 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. That is, (1) polyvinyl alcohol (polymerization degree 2,000
) Is prepared, and 100 g of this adhesive aqueous solution is mixed with 5 g of spacer particles 26, 10 g of paraffin wax particles (binder particles 28), and an appropriate amount, for example, 10 g of microcapsules 18C. , Small amount of dispersant (such as sodium dodecylbenzenesulfonate)
And stirring to prepare a suspension. (2) The 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 ° C., which is somewhat lower than the heat melting temperature (about 73 ° C.), and the heating state is maintained for about 15 minutes, whereby the paraffin wax particles, that is, the binder particles 26, are thermally fused to each other. Thus, a stone wall structure as shown in FIG. 4 is obtained. As in the case described above, if the strength of the stone wall structure is sufficient with the adhesive strength obtained with the aqueous solution of polyvinyl alcohol or other adhesive, such a heat treatment can be omitted.

Third and second microcapsule layer portions 1
As in the case of 6Y 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 reduced. When the heat melting temperature of the first microcapsule layer is 73 ° C. or less, even if a burst pressure of 2.0 MPa or more accompanied by shearing force is applied to the first microcapsule layer portion 16C, the burst pressure is prevented by the stone wall structure of the binder particles 28. In rare cases, it does not directly reach the microcapsules 18C, so that the microcapsules 18C are not destroyed. However, when the heating temperature for the first microcapsule layer portion 16C becomes 73 ° C. or more of the heat melting temperature of the binder particles 28, the binder particles 28 are melted by heat.
When pressure of more than Pa is applied, microcapsules 18C
Is directly destroyed by the breaking pressure.
The function of the spacer particles 26 included in the first microcapsule layer portion 16C will be described later.

In short, the net result is that 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
6Y contained in each of the microcapsules 18C, 1C
8M and 18Y will be given the temperature / pressure rupture characteristics as shown in the graph of FIG.

More specifically, as is apparent from the graph of FIG. 5, 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
The magenta coloring region (hatched region) M is defined by the thermal melting temperature 150 ° C. of the binder particles 20 contained in the binder particles 20. The temperature T ₂ and the pressure P ₂ contained in the magenta coloring region M are defined.
Is applied to the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, where only the microcapsules 18M are destroyed and the magenta coloring material is released.

Similarly, as is clear from the graph of FIG. 5, 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 film of the microcapsule 18Y in the microcapsule layer portion 16Y and the thermal melting temperature 150 ° C. of the binder particles 20 contained in the third microcapsule layer portion 16Y. shaded area) Y is defined, the yellow - when color regions temperature T ₃ and a pressure P ₁ contained in Y is exerted on the microcapsule layer 14 sensitive pressure sensitive heat the recording medium 10, where only the microcapsule 18Y is destruction Then, the yellow colorant is released.

In short, by appropriately selecting the temperature and pressure to be exerted on the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, the microcapsules 18C, 18M and 18Y contained in the microcapsule layer 14 are selectively destroyed. It is possible to do. In the first embodiment, the temperatures T ₁ , T _2, and T ₃ are set to, for example, 90 ° C., 130 ° C., and 170 ° C., and the pressures P ₁ , P _2, and P ₃ are set. For example, 0.
1MPa, 1.0MPa and 3.0MPa are set.

Referring to FIG. 6, 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. 6, the pressure-sensitive thermosensitive recording apparatus has a housing 20 having a substantially rectangular shape, and an inlet for introducing the pressure-sensitive thermosensitive recording medium 10 is provided on the upper side wall of the housing 20. 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. 6, the movement path of the pressure-sensitive thermosensitive recording medium 10 is indicated by a dashed line 26. During color image recording, the pressure-sensitive heat-sensitive recording medium 10 is introduced into the inlet 22 and moved along the movement path 26. Later outlet 2
It is discharged from 4.

A thermal head support 28 is provided at a predetermined position in the housing 20, and a part of the moving path 26 is defined by the thermal head support 28. A first thermal head 30C, a second thermal head 30M, and a third thermal head 30Y are sequentially mounted on the thermal head support 28 from the inlet 22 to the outlet 24, and each thermal head is pressure-sensitive and heat-sensitive recording. A large number of electric resistance elements, that is, heating elements, are arranged in a straight line along the direction in which the medium 10 moves. The first, second and third thermal heads 3
Each of OC, 30M, and 30Y includes n heating elements.

Referring to FIG. 7, the first thermal head
Some of the n heating elements included in 30C are denoted by reference numerals.
R_c1, R_c2And R_c3, The second thermal head 3
A part of n heating elements included in 0M is denoted by a reference symbol R._m1,
R_m2And R_m3And the third thermal head 30Y
Some of the n heating elements included are denoted by reference_y1, R_y2Passing
And R_y3Indicated by As is apparent from FIG.
Thermal element R_c1, R_c2, R_c3, ... R_cn, N heating elements
R_m1, R_m2, R_m3, ... R_mnAnd n heating elements R_y1, R
_y2, R_y3, ... R_ynAre arranged in a matrix of 3 rows and n columns
And three corresponding heating elements included in each of the three rows
(For example, R_c2, R_m2And R_y2) Is a pressure-sensitive thermosensitive recording medium 1
They are aligned with each other along the 0 movement direction.

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.).

Further, n second thermal heads 30M
Heating element R_m1, R_m2, R_m3, ... R _mnIs the second thermal
The second thermal circuit is connected to the head drive circuit 31M.
By the head driving circuit 31M, n heating elements R_m1, R
_m2, R_m3, ... R_mnIs the magenta pixel data for one line
Therefore, it is selectively energized to generate heat, and its heat generation temperature
Are the bilayers contained in the second microcapsule layer portion 16M.
And the third microcapsule.
Thermal melting of binder particles 20 contained in cell layer portion 16Y
Temperature T between 150 ° C_Two(130 ° C).

Similarly, n of the third thermal head 30Y
Number of 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 number of heating elements R _y1,
Ry2 , _Ry3 ,... _Ryn are selectively energized in accordance with one line of yellow pixel data to generate heat, and the heat generation temperature is determined by the thermal melting of the binder particles 20 contained in the third microcapsule layer portion 16Y. Temperature T over 150 ° C
₃ (170 ° C).

As shown in FIG. 6, 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 apply a pressure P ₃ (for example, 3.0 MPa) exceeding 2.0 MPa to the first roller platen 32C, so that the first roller platen 32C exerts the pressure P ₃
(For example, 3.0 MPa), and is brought into pressure contact with the first thermal head 30C.

Further, 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. The second pressure applying spring means 34M is
0.2Mpa and 2.0M for roller platen 32M
It is configured to exert pressure P ₂ (e.g., 1.0 MPa) between Pa, thereby the second roller platen 32M is brought into pressure contact against the second thermal head 30M at a pressure P ₂ (1.0 MPa).

Similarly, a third roller platen 32Y is applied to the third thermal head 30Y, and a third pressure applying spring means 34Y is applied to the third roller platen 32Y.
Are combined. The third pressure applying spring means 34Y is configured to apply a pressure P ₁ (for example, 0.1 MPa) exceeding 0.02 MPa to the third roller platen 32Y,
As a result, the third roller platen 32Y applies pressure P ₁ (0.
At 1 MPa), it is pressed against the third thermal head 30Y.

When a color image is recorded on the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10, each of the above-described heating elements is a pixel unit (ie, 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 100 μm. .

In FIG. 6, reference numeral 36 indicates a control circuit board for controlling driving of the first, second and third thermal heads 30C, 30M and 30Y, and reference numeral 38 indicates a power supply device. The first, second, and third thermal heads 30C, 30C are provided by the power supply device 38.
M and 30Y heating elements and control circuit board 36
And so on.

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 and third thermal heads 30C, each of the heating elements 30M and 30Y is _{(R c1, ... R cn;} R y1, ... R yn; R m1, ... R mn) so as to contact with .

Next, a description will be given of a color forming 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 and 18Y because of the stone wall structure of the binder particles (20, 24, 28).

[0058] However, the heating elements R _c1 of the first thermal head _{30C, R c2, R c3,} ... When any of R _cn is energized, the energized heating elements (R _c1, ... R _cn) is 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 melted, and the stone wall structure (of the first microcapsule layer portion 16C) in the application area is broken. At this time, the heating elements (R _c1 ,...)
R _cn ) penetrates into the first microcapsule layer portion 16C as shown in FIG.
A pressure P ₃ (3.0 MPa) accompanied by a shearing force is applied to C. 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. 8 does not show the wax hot melt produced by the 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 does not directly affect each of the microcapsules 18C, 18M and 18Y because of the stone wall structure of the binder particles (20, 24, 28).

[0061] 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 melted by heat and the stone wall structure (first and second
Of the microcapsule layer portions 16C and 16M are destroyed. At this time, the heating elements (R _m1 ,..., R _mn ) are connected to the first and second microcapsule layer portions 16C as shown in FIG.
And microcapsule 1 that penetrates 16M
Burst pressure P ₂ (1.0MPa) with shear force at 8C and 18M
Effect. Although microcapsules 18C as described above can withstand the burst pressure P ₂ (1.0 MPa), but the burst pressure P ₂ microcapsules 18 that received the (1.0 MPa)
M is destroyed, and the magenta color material is released from there, and the magenta dots are colored there.

Although FIG. 9 does not show the wax hot melt produced by the hot melting of the binder particles 28 and 24 in order to avoid complicating the drawing, the first, second and third micro melts are not shown. Capsule layer portions 16C, 16M and 16
Y will penetrate into the voids of the 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 has a 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 and 18Y because of the stone wall structure of the binder particles (20, 24, 28).

[0064] 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
Binder particles 2 contained in each of 6M and 16Y
8, 24 and 20 hot melting temperatures (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 melted its application area The stone wall structure (of the first, second and third microcapsule layer portions 16C, 16M and 16Y) is destroyed,
At this time, the heating elements (R _y1 ,... R _yn ) are connected to the first, second and third microcapsule layer portions 16 as shown in FIG.
C, 16M and 16Y, and exerts a breaking pressure P ₁ (0.1 MPa) accompanied by a shearing force on the microcapsules 18C, 18M and 18Y therein. As described above, microcapsules 18C and 18M can withstand burst pressure P ₁ (0.1 MPa), but burst pressure P ₁ (0.1 MPa).
The microcapsules 18Y that have received the ink are destroyed, and the yellow color material is released from the microcapsules 18Y, and yellow dots are developed there.

FIG. 10 does not show the wax hot melt produced by the hot 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 in the voids of the stone wall structure and in the structure of the sheet paper 12.

Thus, a full-color image can be formed on the microcapsule layer 14 of the pressure-sensitive thermosensitive recording medium 10 by three primary color dots, that is, cyan dots, magenta dots, and yellow dots, which are developed based on color pixel signals. Becomes Needless to say, in such a full-color image, a blue dot is obtained by superimposing a cyan dot and a magenta dot, and a green dot is obtained by superimposing a cyan dot and a yellow dot.
Red dots are obtained by superimposing magenta dots and yellow dots, and black dots are obtained by superimposing cyan dots, magenta dots, and yellow dots.

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 melted by the energized heating elements ( _Rm1 ,... _Rmn ). Next, the second microcapsule layer portion 16M
The binder particles 24 inside are thermally melted. That is, the heating elements (R _m1 ,..., R _mn )
The state in which the heating elements (R _m1 ,..., R _mn ) have entered the first microcapsule layer portion 16C (that is, the state as shown in FIG. 8) is a transient state before entering the microcapsule layer portion 16M. Appears for a moment. At this time, the microcapsules 18C in the first microcapsule layer portion 16C receive the breaking pressure P ₂ (1.0 MPa) accompanied by the shearing force, but the wall film of the microcapsules 18C has the shearing force as described above. Since the film thickness can withstand the pressure P ₂ (1.0 MPa), the microcapsules 18C cannot be broken in principle.

However, the average particle diameter 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 can be 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 formed by the first microcapsule layer portion 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 can be said for the spacer particles 22 contained 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 the microcapsules 18C or 18M can have a uniform particle size, that is, if the 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.

As is clear 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 first embodiment, phthalocyanine blue is used as the cyan dye of the cyan color material, and 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, but a leuco dye which develops each color (cyan, magenta, yellow) by a chemical reaction with a developer is used. Can also. As is well known, 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 that develop cyan include benzoyl leuco methylene blue (BLMB) and crystal violet lactone (CVL), and leuco dyes that develop magenta include R-Dye manufactured by Yamada Chemical Co., Ltd. 500 and Re made by Yamamoto Kasei
d-3. Examples of leuco dyes that form yellow include IR-3 (Pergascript Yellow) manufactured by Ciba-Geigy and Fcolor Yellow 17 manufactured by Yamamoto Kasei. 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 microcapsule layer portions 16C, 16M, and 1M.
6Y.

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 first embodiment, KMC-113 manufactured by Kureha Chemical Co., Ltd. is used as a vehicle (transparent oil) for the cyan, magenta and yellow color 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 first embodiment described above, 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), a high melting point thermoplastic resin which is not thermoplasticized at least at 250 ° C., for example, a polyamide resin, a polyimide resin, etc., can be used in place of the thermosetting resin. In that case, it is a matter of course that the high melting point thermoplastic resin to be used can exhibit a desired burst pressure characteristic curve (PC, PM, PY).

Furthermore, in the above-described first embodiment, hydroxyapatite is used as the material of the spacer particles (22, 26), but other inorganic materials, such as silica, calcium carbonate, and titanium dioxide, are used. Or a suitable resin material, such as polyimide,
Polyamide, Teflon, polycarbonate and the like may be used.

Further, various additives are added to each microcapsule layer portion (1) 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). For example, as such an additive, each thermal head (3
0C, 30M, 30Y), an adhesion inhibitor for preventing the adhesion of the molten wax and the release color material to the heating element, a fixing agent (so-called filler) for quickly adsorbing and fixing the release color material, and a fading of the recorded image. Examples thereof include an ultraviolet blocking agent and an antioxidant for prevention.

Further, in the first embodiment, the first, second and third microcapsule layer portions 16C, 1C
Each of 6M and 16Y has a stone wall structure,
Each microcapsule layer (16C, 16M, 16Y)
About each corresponding microcapsule (18
C, 18M, 18Y) and, if necessary, the spacer particles (26, 28)) may be formed as a solid wax binder layer in which the spacer particles are evenly distributed.

For example, the third microcapsule layer portion 1
The case where 6Y is formed as a solid wax binder layer will be described.
Gram of PPW-5 (polypropylene wax powder), microcapsule 1 of predetermined amount (for example, 10 g)
The suspension mixed with 8Y and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate) was sprayed onto the sheet paper 12 at a rate of about 5 grams per square meter, air-dried once, and then heated in an oven. When heating in PPW, the heating temperature should be at least PPW-
5 Set to a temperature equal to or higher than the thermal melting temperature (about 150 ° C) of (polypropylene wax powder). Thus, CWP-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.

Further, in the first embodiment, the microcapsule layer 14 is formed in order to form a full-color image.
Has a three-layer structure, but the microcapsule layer 14 may have a single-layer structure to form a monochromatic image.
In this case, a black colorant is generally encapsulated in the microcapsules in the microcapsule layer having a single-layer structure. Of course, when a two-color image is formed, the microcapsule layer 14 has a two-layer structure.

Referring to FIG. 11, a second embodiment of a pressure-sensitive and heat-sensitive recording medium according to the present invention is indicated generally by reference numeral 40, and has the same components as those of the above-described first embodiment. The same components are denoted by the same reference numerals. In the second embodiment shown in FIG. 11, the third microcapsule layer 16Y of the first embodiment is formed by a heat-sensitive yellow.
This corresponds to the one replaced by the coloring layer 16Y '.

In the second embodiment, first, the sheet paper 12
A heat-sensitive yellow coloring layer 16Y 'for recording a yellow image is formed on the heat-sensitive yellow coloring layer 16Y'.
Y 'usually has a white color, but is configured to develop a yellow color when heated to a temperature higher than its yellow coloring temperature. For example, in the second embodiment, a heat-sensitive yellow
The yellow coloring temperature of the coloring layer 16Y 'is set at about 150 ° C.

The heat-sensitive yellow-color-forming layer 16Y 'comprises a yellow-color-forming agent, a developer and a sensitizer. As the yellow-color-forming agent, a suitable yellow-color-forming leuco dye such as IR-3 manufactured by Ciba-Geigy is used. (Pergascript Yellow), for example, bisphenol A is used as a developer, and DPS (diphenyl sulfone) is used as a sensitizer.

The formation of the heat-sensitive yellow-color-forming layer 16Y 'can be performed by the following method. That is,
Prepare a 2% aqueous solution of polyvinyl alcohol (degree of polymerization 2,000), and add 10 grams of IR-3 (Pergascript Yellow) to 100 grams of this aqueous polyvinyl alcohol solution.
And 10 g of bisphenol A, an appropriate amount of DPS (diphenylsulfone), and a small amount of a dispersant (such as sodium dodecylbenzenesulfonate), and then mixed with a stirrer called a homogenizer (22,000 rpm). By stirring over time, a coating solution having an average particle size of 0.6 to 1 μm is prepared. Next, the coating solution is sprayed onto the sheet paper 42 in an amount of 3 to 5 grams per square meter and naturally dried to obtain a heat-sensitive yellow color 16Y '.
The sensitizer DPS is used in such an amount that a desired color density can be obtained at about 150 ° C., for example.

A microcapsule layer 14 'having a two-layer structure is formed on the heat-sensitive yellow-color-forming layer 16Y' obtained as described above. This microcapsule layer 14 'is used for recording a cyan image. 1 microcapsule layer portion 16C and a second microcapsule layer portion 16M for recording a magenta image, and the second microcapsule layer portion 16M is formed on the heat-sensitive yellow-color-forming layer 16Y 'of the sheet paper 12. Formed and then the first microcapsule layer portion 16C is
It is formed on M. Of course, the first and second microcapsule layer portions 16C and 16M are formed in the same manner as in the above-described first embodiment.

Thus, for the pressure-sensitive and heat-sensitive recording medium 40 of the second embodiment, a cyan coloring region C and a magenta coloring region M as shown in the graph of FIG. 12 are defined, and these coloring regions are shown in the graph of FIG. These are substantially the same as the cyan coloring region C and the magenta coloring region M shown. On the other hand, in the pressure-sensitive thermosensitive recording medium 40, the yellow-colored area Y is defined only by the temperature irrespective of the pressure. In this embodiment, the temperature area of about 150 ° C. or more is the yellow-colored area Y.
As in the case of the first embodiment, a color image is recorded on the microcapsule layer 14 'of the pressure-sensitive and heat-sensitive recording medium 40 shown in FIG. 11 by using an image recording apparatus as shown in FIGS. Is possible, but then the third
Setting of the pressing force of the pressure applying spring means 34Y, that is, the third thermal head 30 by the third roller platen 32Y.
For the setting of the pressing force (P ₁ ) exerted on Y, for example,
Such a pressure is necessary for reliably transporting the pressure-sensitive thermosensitive recording medium 40 during rotation of the third roller platen 32Y.
0Y is the microcapsule layer 1 of the pressure-sensitive thermosensitive recording medium 40
It is also necessary to bring the heat generation into close contact with the microcapsule layer 14 'by closely adhering to the microcapsule layer 14'. In short, the coloring of cyan dots and magenta dots on the microcapsule layer 14 'of the pressure-sensitive thermosensitive recording medium 40 shown in FIG. 11 is substantially the same as in the first embodiment, and in the second embodiment. Only the color of the yellow dot differs from that of the first embodiment.

The coloring of yellow dots on the pressure-sensitive thermosensitive recording medium 40 will be described in detail. The pressure-sensitive thermosensitive recording medium 40 is composed of a third sal head 30Y and a third roller platen 32Y.
When any one of the heating elements (R _y1 ,... _Ryn ) of the third thermal head is energized, the energized heating element is connected to the first and second microcapsule layer portions. A temperature T ₃ higher than the thermal melting temperature (73 ° C., 108 ° C.) of the binder particles 28 and 24 contained in 46C and 46M, respectively, and higher than the yellow color developing temperature (150 ° C.) of the thermosensitive yellow-color-forming layer 16Y ′. (170 ° C). In the heating area, the heat-sensitive yellow-color-forming layer 16Y '
The yellow color developing agent therein was heat-melted together with a color developer (bisphenol A) and a sensitizer (DPS), whereby yellow
The color former chemically reacts with the color developer to give yellow. On the other hand, the microcapsules 18C and 18M, the spacer particles 26 and 22 and the molten binder materials 28 and 24 are pressed into the hot-melted yellow color former and developer,
As a result, the heated area is colored as yellow dots.

The microcapsules 18C and 18M
Is pressed into the hot-melted yellow color former and developer, both microcapsules 18C and 18M are subjected to pressure (0.01 MPa), but the wall film of the microcapsules is as described above. Pressure (0.01
MPa), the microcapsule 1
8C and 18M are not destroyed.

In the second embodiment, if necessary, a powder (filler) such as a wax powder or silica is added to the above-mentioned coating solution for forming the heat-sensitive yellow-color-forming layer 16Y '. In this case, it is possible to prevent the yellow-coloring agent and the developer in the heat-melted state from adhering to the heating element of the third thermal head 30Y by the wax powder, and to prevent the yellow-coloring agent and the developer from being heated. The fixability of the yellow color former is improved by a powder (filler) such as silica. After the formation of the heat-sensitive yellow-color-forming layer 16Y ', the surface thereof may be subjected to an appropriate surface treatment, for example, a calendering treatment or an overcoat treatment, if necessary.

The second embodiment described above also has
It should be understood that various changes or modifications described for the first embodiment described above can be applied. In the second embodiment, the microcapsules 18C
When a leuco dye is used as a color material for each of the first and second microcapsules, the first and second microcapsule layer portions 16C and 16M contain a color developer, respectively. -Coloring layer 16
It can be used for yellow coloring at Y ', in which case the developer (bisphenol A) can be omitted from the thermosensitive yellow coloring layer 16Y'.

[0096]

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 sectional view schematically showing a part of a first embodiment of a pressure-sensitive thermosensitive recording medium according to the present invention.

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

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

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

FIG. 5 is a graph showing temperature / pressure rupture characteristics of three types of microcapsules included in the first, second, and third microcapsule layer portions of the pressure-sensitive thermosensitive recording medium shown in FIG.

FIG. 6 is a schematic sectional view showing an example of an image recording apparatus that performs color image recording on the pressure-sensitive heat-sensitive recording medium of FIG.

FIG. 7 is a control block diagram of first, second, and third thermal heads included in the image recording device of FIG. 6;

FIG. 8 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. 1 by the heating elements of the first thermal head of the image recording apparatus of FIG. FIG.

9 is a schematic cross-sectional view schematically showing a state in which magenta dots are colored on the second microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. 1 by the heating elements of the second thermal head of the image recording apparatus of FIG. FIG.

10 is a schematic diagram schematically showing a state in which yellow dots are formed on the third microcapsule layer of the pressure-sensitive thermosensitive recording medium of FIG. 1 by the heating element of the third thermal head of the image recording apparatus of FIG. 6; It is sectional drawing.

FIG. 11 is a schematic sectional view schematically showing a part of a second embodiment of the pressure-sensitive thermosensitive recording medium according to the present invention.

FIG. 12 shows temperature / pressure rupture characteristics of two types of microcapsules included in the first and second microcapsule layers of the pressure-sensitive thermosensitive recording medium shown in FIG. 3 is a graph showing the color development temperature characteristics of a thermosensitive color development layer.

[Explanation of symbols]

 10.40 pressure-sensitive thermosensitive recording medium 12 support (sheet paper) 14.14 'microcapsule layer 16C first microcapsule layer 16M second microcapsule layer 16Y third microcapsule layer 16Y' thermosensitive yellow -Coloring layer 18Y / 18M / 18Y Microcapsule 20 Pressure-sensitive thermal recording device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Shinbo 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. (72) Inventor Hiroshi Inogari 6-7-1 Nakaokacho, Iwaki-shi, Fukushima Prefecture F term (reference) 2H026 BB02 BB21 CC07 DD48 FF05 FF07 2H085 BB02 BB21 CC07 CD01 CD09 2H111 BA03 BA14 BA24 BA38 BA47 BA48 BA49 BA52 BA71

Claims (27)

[Claims] 1. A pressure-sensitive thermosensitive recording medium comprising a support and a microcapsule layer coated on the surface of the support, wherein the microcapsule layer is distributed in a plurality of binder materials evenly. A pressure-sensitive thermosensitive recording medium comprising microcapsules, each of which contains a coloring material, wherein the binder material has a predetermined heat melting temperature, and the microcapsules in the microcapsule layer are the binder. A pressure-sensitive and heat-sensitive recording medium characterized by having a pressure-rupture property of being destroyed under a predetermined pressure in a heat-softened state or a heat-melted state of a material. 2. A pressure-sensitive thermosensitive recording medium according to claim 1, wherein said binder material comprises a wax material having a melting point substantially corresponding to said predetermined heat melting temperature. Medium. 3. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein said binder material is made of a low melting point thermoplastic resin material having a melting point substantially corresponding to said predetermined heat melting temperature. Pressure sensitive thermosensitive recording medium. 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 has a stone wall structure. A pressure-sensitive thermosensitive recording medium characterized by being formed as: 5. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein said color material comprises a vehicle and a dye dispersed or dissolved in said vehicle. Pressure and heat sensitive recording medium. 6. The pressure-sensitive heat-sensitive recording medium according to claim 5, wherein a leuco dye is used as the dye, and a developer of the leuco dye is contained in the microcapsule layer. Thermal recording medium. 7. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein a wall film of the microcapsule is formed of a heat-resistant synthetic resin material. recoding media. 8. A pressure-sensitive thermosensitive recording medium according to claim 7, wherein said heat-resistant synthetic resin material is a thermosetting resin. 9. The pressure-sensitive thermosensitive recording medium according to claim 7, wherein said heat-resistant synthetic resin material is a high melting point thermoplastic resin. 10. A pressure-sensitive and heat-sensitive recording medium comprising a support and a microcapsule layer applied to the surface of the support, wherein the microcapsule layer is composed of first, second and third microcapsule layers. 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 is formed on the second microcapsule layer portion, wherein the first microcapsule layer portion comprises a plurality of first microcapsules uniformly 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 first microcapsules uniformly distributed in a second binder material. A plurality of microcapsules, each of the second microcapsules having a second colorant encapsulated therein, wherein the third microcapsule layer portion is evenly distributed in a third binder material. A pressure-sensitive thermosensitive recording medium comprising third microcapsules, each of which encapsulates a third coloring material, wherein the first binder material has a first heat melting temperature. And a first microcapsule in the first microcapsule layer portion has a pressure rupture property in which the first microcapsule is ruptured under a first pressure in a heat softening state or a heat melting state of the first binder material, The second binder material has a second heat melting temperature that is higher than the first heat melting temperature, and a second microcapsule in the second microcapsule layer portion includes a second microcapsule of the second binder material. Thermal softening state Others wherein under thermal melt 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.
Pressure-sensitive recording medium characterized by having a pressure rupture characteristic of being ruptured under a third pressure lower than the pressure. 11. The pressure-sensitive thermosensitive recording medium according to claim 10, 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 having a particle size smaller than the third average particle size. 12. The pressure-sensitive thermosensitive recording medium according to claim 10, 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. 13. The pressure-sensitive thermosensitive recording medium according to claim 12, wherein said first and second spacer particles are formed of an inorganic material. 14. The pressure-sensitive thermosensitive recording medium according to claim 12, wherein said first and second spacer particles are formed from a high melting point synthetic resin material. 15. The method according to claim 10, wherein:
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. 16. The method according to claim 10, wherein:
3. The pressure-sensitive thermosensitive recording medium according to item 1, wherein the first and second
And a third color material comprising a vehicle and a dye dispersed or dissolved in the vehicle. 17. The pressure-sensitive and heat-sensitive recording medium according to claim 16, wherein a leuco dye is used as the dye, and the first, second and third microcapsule layer portions are each formed of a leuco dye. A pressure-sensitive heat-sensitive recording medium characterized by containing a coloring agent. 18. The method according to claim 10, wherein:
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. 19. A pressure-sensitive thermosensitive recording medium comprising a support, a thermosensitive coloring layer applied on the surface of the support, and a microcapsule layer applied on the thermosensitive coloring layer, wherein the microcapsules A layer comprising first and second microcapsule layer portions, wherein the second microcapsule layer portion is formed on a surface of the thermosensitive coloring layer;
A microcapsule layer portion is formed on the second microcapsule layer portion, and the first microcapsule layer portion comprises a plurality of first microcapsules uniformly distributed in a first binder material. A first coloring material is encapsulated in each of the first microcapsules, and the second microcapsule layer portion is formed of a plurality of second microcapsules evenly distributed in a second binder material. Wherein in each of the second microcapsules, a pressure-sensitive thermosensitive recording medium in which a second coloring material is encapsulated, wherein the first binder material has a first heat melting temperature; A first microcapsule in a microcapsule layer portion having a pressure rupture property in which the first microcapsule is ruptured under a first pressure in a heat-softened state or a heat-melted state of the first binder material; The second microcapsule in the second microcapsule layer portion has a second soft melting temperature higher than the first hot melting temperature, and the second microcapsule in the second microcapsule layer portion has a heat-softened state of the second binder material; The first in a hot melt state
Having a pressure rupture property that is ruptured under a second pressure lower than the pressure of the second binder material, wherein the thermosensitive coloring layer has a pressure rupture property that is higher than a second heat melting temperature of the second binder material. 2. A pressure-sensitive thermosensitive recording medium which develops a color different from each of the two color materials. 20. The pressure-sensitive thermosensitive recording medium according to claim 19, wherein the average particle size of the first microcapsules is smaller than the average particle size of the second microcapsules. Medium. 21. The pressure-sensitive thermosensitive recording medium according to claim 19, 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. 22. The pressure-sensitive thermosensitive recording medium according to claim 21, wherein the spacer particles are formed of an inorganic material. 23. The pressure-sensitive thermosensitive recording medium according to claim 21, wherein said spacer particles are formed from a high melting point synthetic resin material. 24. Any one of claims 19 to 23
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. 25. Any one of claims 19 to 24.
4. The pressure-sensitive thermosensitive recording medium according to claim 1, wherein each of the first and second coloring materials comprises a vehicle and a dye dispersed or dissolved in the vehicle. 26. The pressure-sensitive thermosensitive recording medium according to claim 25, wherein a leuco dye is used as the dye, and a developer of the leuco dye is provided in each of the first and second microcapsule layer portions. A pressure-sensitive thermosensitive recording medium characterized by being included. 27. Any one of claims 19 to 26
In the pressure-sensitive thermosensitive recording medium described in the paragraph, the first and second coloring materials constitute two of the three primary colors, and the color developed by the thermosensitive coloring layer constitutes the remaining colors of the three primary colors. A pressure-sensitive heat-sensitive recording medium characterized by the above-mentioned.