JPH0568871A - Microcapsule and picture forming device - Google Patents

Abstract

PURPOSE:To obtain a microcapsule having sufficient mechanical strength to obviate the accidental breakage and capable of being easily broken with a low pressure in development by encapsulating a volatile expanding agent into a microcapsule contg. a coloring matter and with the mechanical strength changed by the reaction with light. CONSTITUTION:A microcapsule 1 consists of an outer wall 2 and an encapsulant 3. Polyamide resin, polyurethane resin, etc., are exemplified as the material for forming the outer wall 2, and the thickness of the outer wall 2 is ordinarily controlled to about 0.1 to 5mum. The encapsulant 3 to be encapsulated into the outer wall 2 contains at least a coloring matter and further a volatile expanding agent and a photosetting material. An org. solvent having 50 to 150 deg.C b.p. is used as the expanding agent, and hexane, heptane, dimethyl ether, etc., are exemplified as the org. solvent. The encapsulant 3 consists of about 1-20 pts.wt. of the coloring matter, about 20-80 pts.wt. of the photosetting material and about 20-80 pts.wt. of the expanding agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule preferably used for image formation and an image forming apparatus using a toner composed of the microcapsule.

[0002]

2. Description of the Related Art In recent years, microcapsules have come to be used in various fields. For example, in the field of image formation, research has been conducted on microcapsule toners. Specifically, a toner comprising microcapsules containing a pigment body such as a dye precursor and a photocurable substance and having a mechanical strength that changes in response to light is disclosed in JP-A-3-779.
No. 61, No. 3-80258 and the like.

On the other hand, an image is formed on an image receiving paper by a developing method in which a toner composed of such microcapsules is used, and after the toner composed of the microcapsules is exposed, only the toner composed of microcapsules having weak strength is destroyed by pressurization. An image forming apparatus for forming is disclosed in Japanese Patent Laid-Open No. 3-80258.
It is disclosed in Japanese Patent Publication No. 3-92856 and the like.
This image forming apparatus has a microcapsule toner applying unit that charges a toner composed of microcapsules and holds the toner on a carrier, and causes the toner on the carrier to adhere to the carrier by an electrostatic force.

[0004]

However, in the conventional toner composed of microcapsules, the mechanical strength of the outer wall encapsulating the pigment body such as the dye precursor is not always sufficient, and when used in the above-mentioned image forming apparatus, for example. However, there is a problem that the outer wall of the microcapsule toner applying means is easily broken, and inclusions such as a pigment body may flow out.

Therefore, in order to solve this problem, a toner composed of microcapsules in which the film thickness of the outer wall is increased to improve the mechanical strength is used.
When this toner is used, it is usually 500 to 10 during pressure development.
A high pressure of about 00 kg / cm ² is required, and as a result, a strong pressurizing means is required, which makes it difficult to reduce the size and cost of the image forming apparatus.

The present invention has been made under such circumstances, and the object of the present invention is that, if it is used for toner, for example, it will not be destroyed by the microcapsule toner coating mechanism, and at the time of development. An object of the present invention is to provide a microcapsule that is destroyed by a smaller pressure than before and a small-sized and inexpensive image forming apparatus that can use a toner using the microcapsule.

[0007]

In order to achieve the above-mentioned object, the microcapsule of the present invention contains at least a pigment body and has a volatile property in the microcapsule which changes mechanical strength in response to light. In addition, the image forming apparatus of the present invention comprises an exposing agent, a microcapsule toner applying section for applying a microcapsule toner to the image receiving paper, and a pressure developing section. The microcapsule heating means for heating the microcapsule toner exposed by the exposing section is provided.

[0008]

The microcapsule of the present invention contains at least a pigment body and has a volatile expanding agent in the microcapsule whose mechanical strength changes in response to light.
When the microcapsules are exposed to light, the photocurable substance contained therein is cured by a polymerization reaction, and the mechanical strength of the microcapsules increases. On the other hand, in the unexposed microcapsules, the mechanical strength does not change because the photocurable resin contained therein does not polymerize. When the microcapsules that have increased mechanical strength by exposure and the microcapsules that have no change in mechanical strength due to non-exposure are heated uniformly, in the microcapsules that are not exposed, the encapsulation volatilized The outer wall is expanded and expanded by the swelling agent. On the other hand, in the microcapsules cured by exposure, since the volatile expanding agent is contained by the cured photocurable substance, the microcapsules do not expand even when heated. Thus, when the outer wall is expanded by the expanding agent evaporated by heating and the expanding microcapsules and the photocurable substance that is hardened and the expanding agent is contained and the microcapsules that are not expanded by heating are pressed, The expanded microcapsules are more easily pressurized than the unexpanded microcapsules. In addition, the expanded microcapsules have a thinner outer wall film thickness than the unexpanded microcapsules and the internal pressure is high, so that the external walls are easily destroyed when pressed, and inclusions such as plastids are included. Is easy to release. Therefore, if this microcapsule is used for toner, for example, it will not be broken by the microcapsule toner application mechanism, and will be broken at the time of development with a smaller pressure than before.

Further, the image forming apparatus of the present invention is an image forming apparatus including an exposing section, a microcapsule toner applying section for applying microcapsule toner to an image receiving paper, and a pressure developing section, where the exposing section exposes the image. It also has a microcapsule heating means for heating the microcapsule toner. When a document placed on a document table made of a transparent member is irradiated with light from an exposure unit, the reflected light exposes the microcapsule toner. This microcapsule toner is applied to the image receiving paper in the microcapsule toner applying section, further heated by the microcapsule heating means, and then pressurized in the pressure developing section for development processing, and a color image is formed on the image receiving paper. .. Therefore,
In this image forming apparatus, the toner containing the microcapsules of the present invention can be preferably used, and by using the toner containing the microcapsules, a compact and low-cost image forming apparatus can be realized.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of the microcapsule of the present invention.

As shown in FIG. 1, the microcapsule 1 of the present invention comprises an outer wall 2 and an inclusion 3. Examples of the material for forming the outer wall 2 include resins such as polyamide resin, polyurethane resin, polyurea resin, and urea formalin resin.

The thickness of the outer wall 2 is usually 0.1 to 5 μm.
It is about m. The inclusion 3 enclosed inside the outer wall 2 is
It contains at least a pigment and a volatile expanding agent, and also contains a photo-curable substance.

Examples of pigments include inorganic pigments such as chrome yellow, ultramarine, Prussian blue, molybdenum red, titanium yellow, and iron trioxide; azo pigments, phthalocyanine blue, quinacridone, dioxazine violet, isoindolinone, perinone. Organic pigments such as pigments; various dyes such as xanthene dyes, coumarin dyes, merocyanine dyes, cyanine dyes, anthraquinone dyes, azo dyes, merocyanine dyes, leuco dyes; further acetoacetic anilide, anisidine,
p-aminoacetanilide, ethylaniline, 2,4-
Examples include dye precursors such as xylidine. These pigment bodies may be contained singly or in combination of two or more kinds.

The volatile expanding agent has a boiling point of 50.degree.
An organic solvent of 150 ° C., preferably 80 ° C. to 120 ° C. is preferably used. Examples of such an organic solvent include hexane, heptane, pentane, isobutane, cyclohexene, methyl ethyl ketone, methanol, ethanol, epichlorohydrin, acetic acid. Examples thereof include ethyl, diisopropyl ketone, dibutyl ether, dimethyl ether and the like.

The photocurable substance comprises a polymerizable compound and a photopolymerization initiator. Here, as the polymerizable compound, for example, N-vinyl-2-pyrrolidone, bisphenol A diacrylate, bisphenol A dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol methacrylate, pentaerythritol triacrylate, pentaerythritol methacrylate, polyethylene glycol. Diacrylate, polyethylene glycol methacrylate, dipentaerythritol hexaacrylate, dipentaerythritol methacrylate, trimethylolpropane triacrylate,
Examples include trimethylolpropane methacrylate, oligoester acrylate, oligoester methacrylate and the like. These polymerizable compounds may be used alone or in combination of two or more.

The photopolymerization initiator may be any one as long as it is sensitive to light and initiates the polymerization of the above-mentioned polymerizable compound. For example, benzophenone, benzoylalkyl ethers such as benzoylisopropyl ether, Michler's ketone, metal arene compounds, 2 , 4-diethylthioxanthone and the like.

The content ratio of these various components in the inclusion 3 is usually 100 parts by weight of the inclusion and
1 to 20 parts by weight, the photocurable substance is usually about 20 to 80 parts by weight, and the volatile expanding agent is usually 20 to 80 parts by weight, preferably 30 to 50 parts by weight. It is a degree.

The shape of the microcapsule 1 including such an inclusion 3 in the outer wall 2 is substantially spherical, and the diameter thereof is about 1 to 50 μm. The microcapsule 1 is manufactured, for example, as follows.

First, the pigment body, the photocurable substance, and the volatile expanding agent are uniformly mixed in a predetermined ratio to prepare an inclusion-forming mixture. The inclusion-forming mixture is then emulsified in water and subjected to, for example, an interfacial polymerization method, i.
It is encapsulated inside the outer wall 2 by a known microencapsulation method such as an n situ method or a spray granulation method, and the inclusion 3 is the outer wall 2.
The microcapsules 1 encapsulated inside are obtained.

If the microcapsules 1 thus obtained are dried by a drying method such as a spray drying method, a vacuum drying method or a freeze drying method, the microcapsules can be suitably used in an image forming apparatus. Capsule toner is obtained. Here, when the microcapsule toner is required to have fluidity and chargeability, for example, inorganic or organic fine powder or charge control agent powder may be externally added to the periphery of the microcapsule.

Next, the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 2 is an explanatory view showing the outline of an example of the image forming apparatus of the present invention. As shown in FIG. 2, inside the image forming apparatus M, an exposure section 10, a microcapsule toner application section 20 for applying microcapsule toner to an image receiving paper, a pressure development section 30, and an exposure section 10 are used for exposure. The microcapsule heating means 40 for heating the microcapsule toner thus formed is provided, and the endless belt-shaped support 4 for moving the microcapsule toner between the respective parts is provided.

The exposure unit 10 includes, for example, an exposure lamp 11.
And a document table 12 made of a transparent glass plate, and the document table 1
An original cover 14 for covering the original 13 placed on the sheet 2, a filter 14 for adjusting the color tone of an image, and a light shield plate 1
It is composed of 5 and.

The microcapsule toner applying section 20 supplies a toner case 21 for storing toner composed of microcapsules, a toner agitator 22, a toner carrier 23 carrying toner, and a toner carrier 23. And a microcapsule toner 25 stored in the toner case 21.

In the pressure developing section 30, a pair of pressure rollers 31a and 31b are arranged so as to sandwich the microcapsule toner support 4 and the image receiving paper 6 therebetween. The microcapsule toner support 4 is provided between a drive roller 29, a counter roller 27, a heat roller 45 that constitutes microcapsule heating means 40, and a pair of pressure rollers 31a and 31b.

The heating means 40 is means for heating and expanding the microcapsule toner 25. Specifically, for example, a heat roller 45 containing a heating resistor or a heating element such as a halogen lamp, and this heat. Backup roller 46 for closely contacting the roller 45 and the support 4
And have.

The power source 2 is applied to the opposing roller 27.
8 is connected, and an electric field is formed in a region between the opposing roller 27 and the carrier 23. Further, below the microcapsule toner applying section 20, a cleaning unit 50 is installed close to the support 4, and a cleaning blade 51, which is a constituent member of the cleaning unit 50.
Is in contact with the support 4.

Next, the operation of this image forming apparatus will be described. When a start-up switch (not shown) is turned on, the drive roller 29 of the support 4 rotates, and the support 4 is conveyed. In the microcapsule toner applying section 20, the microcapsule toner 25 is carried on the carrier 23 by the rotation of the agitator 22 and the supply body 24. The carried microcapsule toner 25 is transferred to the opposing roller 27 by an electric field formed between the carrier 23 and the opposing roller 27.
Receives electrostatic attraction in the direction of. As a result, the microcapsule toner 25 is applied onto the support 4.

The support 4 coated with the microcapsule toner 25 is conveyed to the lower part of the exposure section 10. Here, the exposure lamp 11 of the exposure unit 10 is turned on, and the document table 12 holding the document 13 moves. As a result, the exposure operation is performed according to the original 13. The light reflected from the original 13 passes through the filter 14 to adjust the color tone of the image and is imaged on the surface of the microcapsule toner 25 applied to the support 4. This allows microcapsule toner 2
No. 5 changes its mechanical strength.

The microcapsule toner 25 exposed as described above is sent between the heat roller 45 and the backup roller 46. Here, it is sent between the heat roller 45 and the backup roller 46. Here, the heat from the heat roller 45 also heats the microcapsule toner 25. Therefore, the mechanical strength does not change because it is not exposed, and the microcapsule toner 25 having weak mechanical strength expands.

Further, the microcapsule toner 25 is conveyed toward the pressure developing section 40. The image receiving paper 6, which is plain paper, is taken out from the paper feeding cassette 61, and the pressure developing unit 4
Sent to 0. In the pressure developing section 40, the support 4 carrying the microcapsule toner 25 and the image receiving paper 6 are passed between the pressure rollers 31a and 31b in a state of being superposed on each other. Among the microcapsule toners 25, the capsule toners 25 that have low mechanical strength and are expanded are selectively pressed and destroyed, and the inclusions 3 of the microcapsule toners 25 flow out. Therefore, an image is formed on the image receiving paper 6, and the image receiving paper 6 is output to the tray 64. The hardened microcapsules are not destroyed by the pressure and remain on the support 4. The support 4 is further conveyed toward the cleaning unit 50. Since the blade 51 of the cleaning unit 50 is in contact with the support 4, the microcapsule toner 25 remaining on the support 4 is scraped off by the blade 51. The microcapsule toner 25 is again applied to the support 4 that has passed through the cleaning unit 50. In addition, although the microcapsules are used as toners in this embodiment, the microcapsules are used as a base material such as a film. It is also possible to use the media obtained by coating.

Next, the behavior of the microcapsule toner 25 in the image forming apparatus M of the present invention will be described with reference to the drawings. FIG. 3 is an explanatory diagram sequentially showing the behavior of the microcapsule toner 25 in the image forming apparatus M of the present invention.

As shown in FIG. 3A, the microcapsule toner 25 composed of the microcapsules 1 in which the inclusion 3 is enclosed inside the outer wall 2 is uniformly held on the support 4 in the image forming apparatus M. Has been done. Here, the microcapsule toner 25 is imagewise exposed through the original or the mask 5.

By this image exposure, the inclusion 3 undergoes a polymerization reaction inside the microcapsules 1b forming the exposed microcapsule toner 25. Therefore, the microcapsules 1b are hardened and the mechanical strength is increased. On the other hand, no change occurs in the unexposed capsule 1a.

Next, as shown in FIG. 3B, the support 4
All microcapsule toners 25 held on
Is heated uniformly. When the temperature of the expander contained therein rises due to this heating, the expander evaporates. At this time, as shown in FIG. 3C, in the uncured microcapsules 1a, the walls are expanded and expanded by the expanded expander. On the other hand, there is no change in the microcapsules 1b that are hardened and have improved mechanical strength.

Next, as shown in FIG. 3D, the image receiving paper 6 is superposed on the surface of the microcapsule toner 25, and in this state, all the microcapsule toner 25 is applied by a pair of upper and lower rollers 7a, 7b. Press. At this time, the uncured, that is, expanded microcapsules 1a are more easily pressed than the cured microcapsules 1b. The expanded microcapsule 1a has an outer wall 2
Is thin and the internal pressure is high, the outer wall 2 is easily broken when the pressure is applied, and the inclusion 3 is easily released. From the destroyed microcapsules 1c, pigment bodies 3b such as pigments, dyes, and dye precursors are released, and the pigment bodies 3b are transferred to the image receiving paper 6. Therefore, according to the image forming apparatus M of the present invention and the microcapsule toner 25 using the microcapsules 1 of the present invention, an image is formed with a lower pressing force as compared with the conventional image forming apparatus.

[0036]

According to the present invention, since it has the above-mentioned structure, it has a sufficient mechanical strength so that it will not be accidentally destroyed when it is handled inside the coating mechanism when it is used for toner, for example. In addition, a microcapsule that is easily destroyed by a smaller pressure than before at the developing stage and a toner that uses the microcapsule can be used to achieve downsizing and weight reduction, and an inexpensive image forming apparatus. Can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the structure of a microcapsule of the present invention.

FIG. 2 is an explanatory diagram showing an example of an image forming apparatus of the present invention.

FIG. 3 is an explanatory view schematically showing the action when the microcapsules of the present invention are used as a toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microcapsule 2 ... Outer wall 3 ... Encapsulation 4 ... Support 6 ... Image receiving paper 10 ... Exposure part 20 ... Microcapsule toner application part 25 ... Microcapsule toner 30 ... Pressure developing part 40 ... Microcapsule heating means M ... Image Forming device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/004 514 7124-2H 7/26 521 7124-2H

Claims (2)

[Claims] 1. A microcapsule which encapsulates at least a pigment and whose mechanical strength changes in response to light, wherein a volatile expanding agent is encapsulated. 2. An image forming apparatus comprising an exposure section, a microcapsule toner application section for applying microcapsule toner to an image receiving paper, and a pressure development section for applying pressure to the microcapsule toner. An image forming apparatus comprising a microcapsule heating means for heating a microcapsule toner.