JPH09265185A - Photosensitive microcapsule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive micrcapsule which can form a sharp image having enough high density, good tone and no blur by controlling the photosensitive wavelength of a photosensitive material included in a cyan-color developing photosensitive microcapsule (C capsule). SOLUTION: The microcapsule consists of a C capsule 1 having a hollow part inside and a photosensitive material 3 which has the max. sensitivity for hardening near 650nm wavelength and fills the inside hollow part of the capsule 1. The capsule wall material 2 contains an optical filter material having a spectral filtering function, namely, a material which absorbs or reflects light in <=600nm wavelength region.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photosensitive microcapsule used when a color image is formed by using light.

[0002]

2. Description of the Related Art Conventionally, as a microcapsule used in an image forming apparatus or the like, for example, a microcapsule containing a photosensitive substance which cures in response to light and a pigment is known. In order to form a color image, photosensitive microcapsules for yellow color development (hereinafter referred to as Y capsules)
And a photosensitive microcapsule for developing magenta (hereinafter referred to as M
Three different types of capsules are prepared, namely, a capsule) and a photosensitive microcapsule for cyan color formation (hereinafter referred to as C capsule). The Y capsule contains a photosensitive material having a maximum curing sensitivity near a wavelength of 450 nm and a yellow image forming material. Wavelength 550 for M capsules
A photosensitive material having maximum curing sensitivity to light near nm and a magenta image forming material are included. The C capsule contains a photosensitive substance having a maximum curing sensitivity to light having a wavelength of about 650 nm and a cyan image forming substance. In order to form an image using such a microcapsule, the following process is usually adopted.

That is, when the microcapsules are exposed to light based on image information, some portions of the photosensitive microcapsules are hardened and some are not.
After that, when external pressure is applied to the microcapsules by, for example, passing the microcapsules on plain paper and passing them through a pair of pressure rollers, the unhardened microcapsules are destroyed, but the hardened microcapsules are cured. Is not destroyed. From the destroyed microcapsules,
The inclusions containing the imaging substance are released. Then, the contents are transferred to the plain paper, so that an image is formed on the plain paper.

[0004]

However, the above-mentioned 3
See Fig. 1 for the photosensitive substance contained in the seed microcapsules.
As shown in, the photosensitivity characteristics overlap.
In particular, the photosensitive wavelength of the photosensitive substance contained in the C capsule extends to around 550 nm. Therefore, when the image is formed, the white part of the image is stained or the image has a poor color tone.

The present invention has been made in order to solve the above-mentioned problems, and the density is sufficiently high and the color tone is good by controlling the photosensitive wavelength of the photosensitive substance contained in the C capsule. Another object of the present invention is to provide a photosensitive microcapsule capable of forming a clear image without bleeding.

[0006]

In order to achieve this object, the photosensitive microcapsule according to claim 1 has a C capsule having a hollow portion inside, and a wavelength of about 650 nm filled in the hollow portion of the capsule. In a microcapsule having a photosensitive substance having maximum curing sensitivity, the capsule wall material contains an optical filter substance having a spectral filter function, that is, a substance capable of absorbing or reflecting light having a wavelength of about 600 nm or less. are doing.

According to the photosensitive microcapsule of the present invention having the above constitution, the photosensitive wavelength of the photosensitive substance contained in the C capsule can be controlled by the filter substance having the optical filter function, and as a result, the concentration Is sufficiently high, the color tone is good, and a clear image without bleeding is formed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view schematically showing a photosensitive microcapsule according to the embodiment of the present invention. The microcapsule 1 is configured to have a capsule wall material portion 2 as an outer shell portion having a hollow portion inside, and a liquid component 3 filled in the hollow portion. Then, the capsule wall material portion 2 of the present embodiment contains an optical filter substance 4 having a spectral filter function.

The liquid component 3 comprises at least a photosensitive substance and an image forming substance.

Here, in each capsule, the image forming substance is dissolved or dispersed in the photosensitive material. As the image forming substance, a dye or pigment which is itself colored is used. Dyes or pigments are commercially available, as well as books such as dye manuals and pigment manuals,
The one with an appropriate color may be selected from those described in the literature.

Particularly preferably, yellow is monoazo, disazo, azocalcium lake, azobarium lake, magenta is quinacridone or calcium lake, and cyan is phthalocyanine.

On the other hand, the photosensitive substance comprises at least a polymerizable substance and a photopolymerization initiator.

Examples of the polymerizable substance include unsaturated compounds such as compounds having an ethylenically unsaturated group and compounds having an epoxy group. However, compounds having an ethylenically unsaturated group having a relatively high photopolymerization rate are preferable. Especially desirable. Examples of the compound having an ethylenically unsaturated group include acrylic acid and salts thereof, acrylic acid esters, acrylamides,
Methacrylic acid and its salts, methacrylic acid esters, methacrylamides, maleic anhydride, maleic acid esters, itaconic acid esters, styrenes, vinyl ethers, vinyl esters, N-vinyl heterocycles, allyl ethers, Examples include allyl esters and their derivatives. More preferably, acrylic acid esters or methacrylic acid esters are used.

Specific examples of acrylic acid esters include:
Butyl acrylate, cyclohexyl acrylate, ethylhexyl acrylate, benzyl acrylate, furfuryl acrylate, ethoxyethyl acrylate,
Tricyclodecanyloxy acrylate, noniphenyloxyethyl acrylate, hexanediol acrylate, 1,3-dioxolane acrylate, hexanediol diacrylate, butanediol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, tricyclodecane dimethylol Diacrylate, tripropylene glycol diacrylate, bisphenol A diacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, hexaacrylate of caprolactone adduct of dipentaerythritol, trimethylolpropane triacrylate, propylene oxide adduct of trimethylolpropane Triacrylate, polyoxyethylene Diacrylate of bisphenol A, polyester acrylate, polyurethane acrylate.

Specific examples of the methacrylic acid esters include butyl methacrylate, cyclohexyl methacrylate, ethylhexyl methacrylate, benzyl methacrylate, furfuryl methacrylate, ethoxyethyl methacrylate, tricyclodecanyloxy methacrylate, noniphenyloxyethyl methacrylate, hexanediol methacrylate, 1,3-dioxolane methacrylate, hexanediol dimethacrylate, butanediol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, tricyclodecane dimethylol dimethacrylate, tripropylene glycol dimethacrylate, bisphenol A dimethacrylate, pentaerythritol trimethacrylate Methacrylate , Dipentaerythritol hexamethacrylate, hexamethacrylate of dipentaerythritol caprolactone adduct, trimethylolpropane trimethacrylate, trimethacrylate of propylene oxide adduct of trimethylolpropane, dimethacrylate of polyoxyethylenated bisphenol A, polyester methacrylate, polyurethane Methacrylate etc. are mentioned. Further, these polymerizable substances may be used alone or as a mixture of two or more kinds.

Particularly preferably, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, hexaacrylate of a caprolactone adduct of dipentaerythritol, and trimethylolpropane triacrylate having three or more acryloyl groups which are unsaturated groups in the molecule. It is preferable that at least one kind of triacrylate of propylene oxide adduct of trimethylolpropane is contained.

The photopolymerization initiator receives light energy to initiate or accelerate the polymerization reaction of the polymerizable substance. The photopolymerization initiator includes aromatic carbonyl compounds, acetophenones,
Organic peroxides, diphenylhalonium salts, organic halides, 2,4,6-substituted-S-triazines, 2,4
A 5-triarylimidazole dimer, an azo compound, a dye borate complex, a metal arene complex, a titanocene compound and the like are used.

Desirably, benzophenone, benzyl,
Xanthone, thioxanthone, anthraquinone, acetophenone, 2,2-dimethyl-2-morpholino-4 '
-Methylthioacetophenone, benzoyl peroxide, 3,3 ', 4,4'-tetrakis (t-butyldioxycarbonyl) benzophenone, diphenyliodonium bromide, diphenyliodonium chloride,
Carbon tetrachloride, carbon tetrabromide, 2,4,6-tristrichloromethyl-S-triazine, (η ⁵ -2,4-cyclopentadien-1-yl) [(1,2,3,4,5,5 6-
[eta]-(1-methylethyl) benzene] iron (1+) hexafluorophosphate (1-) and the like. Further, these photopolymerization initiators may be used alone or as a mixture of two or more kinds.

The photopolymerization initiator is 0.1 to 20% by weight, more preferably 1 to 10% by weight, based on the polymerizable substance.
Used in the ratio of. Usually, if it is 1% or less, the photopolymerization reaction hardly occurs, and if it is 10% or more, the sensitivity is not improved.

Further, in order to improve the photosensitivity of the above-mentioned photosensitive substance, particularly the photosensitivity to wavelength, a sensitizing dye may be used together. As sensitizing dyes, xanthene dyes, coumarin dyes, merocyanine dyes, thiazine dyes, azine dyes, methine dyes, oxazine dyes, phenylmethane dyes, cyanine dyes, azo dyes, anthraquinone dyes , Pyrazoline dyes, stilbene dyes, quinoline dyes and the like can be used.

The material for forming the wall material portion 2 of the microcapsule may be an inorganic substance or an organic substance as long as the wall material portion can be produced by the above-mentioned capsule manufacturing method, but a material that allows sufficient light transmission. Is preferred.

Specific examples include gelatin, gum arabic, starch, sodium alginate, polyvinyl alcohol, polyethylene, polyamide, polyester, polyurethane, polyurea, polyurethane, polystyrene, nitrocellulose, ethyl cellulose, methyl cellulose, melamine-formaldehyde resin, urea-formaldehyde. Examples thereof include resins and their copolymers.

In-supplying the raw material for the wall material only in water
A melamine-formaldehyde resin or a urea-formaldehyde resin, which is relatively easy to manufacture due to the in situ method, is particularly desirable.

When the microcapsules are produced in this manner, it is necessary to disperse or emulsify the composition to be the inclusion in an aqueous medium. At this time, it is desirable that the aqueous medium contains a nonionic or anionic water-soluble polymer.

Examples of the nonionic water-soluble polymer include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polymethyl vinyl ether, hydroxymethyl cellulose and hydroxyethyl cellulose. Examples of the anionic water-soluble polymer include polystyrene sulfinic acid, polystyrene sulfonate, styrene sulfonic acid copolymer, polyvinyl sulfate ester salt, polyvinyl sulfonate, maleic anhydride / styrene copolymer, maleic anhydride / isobutylene. Examples thereof include copolymers.

As the optical filter substance 4 contained in the capsule wall member 2, a substance that absorbs or reflects light having a wavelength of about 600 nm or less is used. For example, cyanine dye, xanthene dye, coumarin dye, merocyanine dye, thiazine dye, azine dye, methine dye, oxazine dye, phenylmethane dye, azo dye, anthraquinone dye, pyrazoline dye ,
Examples include stilbene dyes, quinoline dyes, squarylium dyes, and the like.

Such an optical filter substance 4 is contained in the capsule wall member 2 in a range of approximately 0.1% by weight or more and approximately 10% by weight or less. In the present embodiment, the case where the optical filter substance 4 is added at the time of manufacturing the wall material has been described as an example, but it may be added before that.

Materials used for the base material of the photosensitive recording medium include papers, high-quality papers, papers such as coated papers, polyester, polyethylene, polypropylene, acetyl cellulose, cellulose ester, polyvinyl acetal, polystyrene, polycarbonate, polyethylene terephthalate, There are films such as polyimide and resins, and synthetic paper made of paper and resins. Among these, a film of polyethylene terephthalate or the like is desirable because it is excellent in flatness smoothness, strength, and the like, has a thin thickness of 0.05 mm or less, and has a relatively small volume even in a roll state. Furthermore, a film in which a reflective layer is formed on at least one surface of these films by aluminum vapor deposition or the like has the effect of improving the photosensitivity of the photosensitive recording medium, and is particularly desirable.

In order to form a photosensitive layer by coating microcapsules on the above substrate, a hydrophilic binder is mixed with a dispersion liquid of microcapsules. As the hydrophilic binder, natural substances such as gelatin, cellulose, starch, gum arabic, etc., synthetic polymer substances such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl imidazole, polystyrene sulfonic acid, etc. Used.

[0031]

[Examples] Examples of producing C capsules will be described below.

An acrylic raw material was obtained by mixing pentaerythritol triacrylate and dipentaerythritol hexaacrylate, which are polymerizable substances, in a weight ratio of 1: 1 with a stirrer. A phthalocyanine-based cyan pigment was added to this acrylic raw material, mixed with a stirrer, and kneaded with a three-roll mill for 10 passes to prepare a mill base in which the pigment was dispersed in a polymerizable substance.

Next, the above acrylic raw material was added to this mill base and uniformly mixed by a disperser to prepare a cyan pigment dispersion.

In addition to the cyan pigment dispersion, a squarylium dye which is a wavelength sensitizing dye and a photopolymerization initiator (η ⁵
-2,4-cyclopentadiene-1-yl) [(1,
2,3,4,5,6-η)-(1-methylethyl) benzene] iron (1+) hexafluorophosphate (1
-) Was added, and the mixture was heated to about 50 ° C., mixed and dissolved to obtain a composition to be included in microcapsules.

The composition of the above composition is shown in parts by weight as follows.

100 parts by weight of acrylic raw material (polymerizable compound), 4 parts by weight of pigment, 3 parts by weight of photopolymerization initiator, 0.5 part by weight of wavelength sensitizing dye.

When the curing wavelength characteristic of this composition was measured, it had a maximum curing sensitivity in the visible light region around 650 nm, that is, in the red light region.

Next, a 1: 1 mixed solution of a 5% polystyrene sulfonic acid partial sodium salt aqueous solution as an emulsifier and a 5% styrene-maleic anhydride copolymer aqueous solution was prepared.
To 200 cc of this mixed solution, 100 g of the composition was added, and the mixture was stirred with a homogenizer at 6000 rpm for 5 minutes.
As a result, a so-called O / W emulsion in which the composition was dispersed in water as a continuous layer was obtained.

Separately from this, a commercially available melamine powder is added to a 37% aqueous formaldehyde solution, and a very small amount of a cyanine dye is further added. The pH was adjusted to 9.0 with sodium hydroxide solution and heated at a water temperature of 60 ° C. for 30 minutes to obtain a melamine-formaldehyde prepolymer.

The above-mentioned melamine / formaldehyde prepolymer was added to the O / W emulsion prepared above, and the mixture was kept at a temperature of 50 ° C. for 5 hours while stirring at 100 to 300 revolutions with an Ajihomomixer or the like. Then, it was adjusted to PH7 and cooled to room temperature. As a result, by the in-situ polymerization method, C capsules having the above composition as an inclusion and a melamine-formaldehyde resin as a wall material were obtained. Then, a cyanine dye, which is an optical filter material, is mixed inside the wall material. The addition of the dye forms the wall of the microcapsule made of a magenta transparent body. The magenta transparent body can absorb light of its complementary color, green, and allow only magenta light to reach the inside of the microcapsule. Therefore, when the green light hits the microcapsules, all the light is absorbed by the wall and does not reach the inside. As a result, the contents of the C capsule can flow out by pressure development, and the cyan color can be reproduced faithfully.

Therefore, at least a cyan color-developing microcapsule having a hollow portion inside, wherein the hollow portion of the microcapsule is filled with a photosensitive substance having a maximum curing sensitivity near a wavelength of 650 nm, A microcapsule containing an optical filter substance having a spectral filter function, that is, a substance capable of absorbing or reflecting light having a wavelength of about 600 nm or less, in the wall material portion has a sufficiently high concentration, good color tone, and bleed It can be said that it is possible to form a clear image.

[0042]

As is apparent from the above description, when the photosensitive microcapsule according to claim 1 is used, the photosensitive substance encapsulated in the C capsule can be treated by the filter substance having an optical filter function. The photosensitive wavelength can be controlled, and as a result, a clear image having a sufficiently high density, good color tone and no bleeding can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing the photosensitivity characteristics of various capsules in a conventional microcapsule.

FIG. 2 is a configuration cross-sectional view schematically showing a microcapsule according to an embodiment of the present invention.

[Explanation of symbols]

 1 Micro capsule 2 Capsule wall material 3 Liquid part 4 Optical filter substance

Claims (1)

[Claims] 1. A cyan color forming microcapsule having a hollow portion inside, wherein the hollow portion of the microcapsule is filled with a photosensitive substance having a maximum curing sensitivity in the vicinity of a wavelength of 650 nm. A photosensitive microcapsule characterized in that the part contains an optical filter substance having a spectral filter function, that is, a substance capable of absorbing or reflecting light having a wavelength of about 600 nm or less.