JPH024242A - Light image forming material - Google Patents

Abstract

PURPOSE:To obtain a heat-fixable light image forming material having high water resistance of a light image forming layer by forming a covering layer contg. modified polyvinyl alcohol having Si atoms in a molecule and colloidal silica, on a coated layer. CONSTITUTION:A coated layer contg. microcapsules contg. a leuco dye which develops color by oxidation together with a photooxidizing agent, and a reducing agent, as essential components, is formed on a base body. And a covering layer contg. modified polyvinyl alcohol contg. Si atoms in a molecule and colloidal silica and/or amorphous silica is formed on said coated layer. Thus, a light image forming compsn. having high water resistance and preventing contamination of a heat fixing roll as well as yellowing of a texture is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to photoimage-forming materials, and particularly to heat-fixable leuco dye-based photoimage-forming materials.

More specifically, the present invention relates to a photoimage-forming material in which the photoimage-forming layer has excellent water resistance, little yellowing of the background, and little staining of the heat fixing roll.

"Prior Art" Conventionally, photoimageable materials that can be used for applications such as proofing paper, printout paper, and overlay films are:
Many photographic applications have been made for so-called free radical photography, in which photosensitive areas are visualized by imagewise exposure.

Particularly effective in this regard is the method of radical oxidative color development of various leuco dyes into their corresponding dyes using a photooxidizing agent.

However, because they are sensitive to light, even after exposure to dye images, color formation occurs when exposed to normal room light, bright sunlight, or white light; therefore, they are sensitive to such light. Imaging materials are difficult to handle.

- In order to retain the image once formed, it is necessary to avoid developing color in unexposed areas during image exposure. It is known to preserve the original image by applying a reducing agent solution, such as a free radical scavenger, to the imaged material, for example by spraying or impregnating. However, there remains a major problem in terms of workability and complexity associated with going through a wet bath. Furthermore, for example, Japanese Patent Laid-Open No. 47-12879 proposes a method in which image formation is performed using U-light and fixing is performed by activating a photoreducible substance using visible light. However, in this process, the light is used twice to monopolize the device for that time;
Also, major problems remain in that it is necessary to replace the spectral filter in order to use the two types of light properly. On the other hand, Japanese Patent Publication No. 43-29407 proposes a method in which a reducing heat fixing agent is contained in the photosensitive layer or coated on the photosensitive layer to carry out heat fixing after image exposure. However, this method has a major problem in that the photosensitivity component (leuco dye and photooxidizing agent) and fixing agent coexist in close proximity, resulting in a decrease in sensitivity over time. Furthermore,
Since the above-mentioned photoimage-forming materials are coated onto a support using an organic solvent, explosion-proof measures are required for manufacturing equipment, which is disadvantageous in terms of both safety and cost.

Therefore, in order to solve these problems, we have discovered a photoimage-forming material in which a leuco dye and a photooxidizing agent are encapsulated together in microcapsules, and a reducing agent is present outside the microcapsules. . (Special application No. 62-2591
No. 11) "Problems to be Solved by the Invention" However, even in this photoimage-forming material, the water resistance of the photoimage-forming layer is insufficient, the heat fixing roll gets dirty during heat fixing, and problems occur after heat fixing. It was found that there were problems such as the skin becoming yellow over time.

OBJECT OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-fixable photoimage-forming material whose photoimage-forming layer has excellent water resistance.

Another object of the present invention is to provide a photoimage-forming material which prevents heat fixing roll stains and yellowing of the background after heat fixation.

The above-mentioned object of the present invention is to provide a coating layer on a support, the essential components of which are microcapsules containing at least a leuco dye capable of forming oxidative color and a photo-oxidizing agent, and a reducing agent. A photoimage-forming material formed in a photoimage-forming material, characterized in that a coating layer containing modified polyvinyl alcohol containing silicon atoms in the molecule and colloidal silica and/or amorphous silica is provided on the coating layer. Achieved through materials.

The modified polyvinyl alcohol containing a silicon atom in the molecule used in the coating layer of the present invention is not particularly limited as long as it contains a silicon atom in the molecule, but usually the silicon atom contained in the molecule is an alkoxy group. , 7 siloxy group, a hydroxyl group obtained by hydrolysis, or a reactive substituent thereof such as an alkali metal base thereof are preferred.

Details of the method for producing such modified polyvinyl alcohol containing silicon atoms in the molecule are described in JP-A-58-193189. The modified polyvinyl alcohol containing silicon atoms in the molecule used in the present invention can be produced by these known methods, but it may also be produced by other methods.

Among these, a saponified product of a copolymer of vinyl acetate and an olefinically unsaturated monomer containing a silicon atom in the molecule represented by the following formula (1) is preferred;
Particularly preferred are saponified copolymers of vinyltrimethoxysilane and/or -vinyltributoxysilane and vinyl acetate.

General formula [1] CR2=CH-(CR2), -S i -(R2)3
-□(R'),,.

(However, n is an integer of 0 to 4, m is an integer of 0 to 2, R1 is an alkyl group having 1 to 5 carbon atoms, R2 is an alkoxy group or acyloxy group having 1 to 40 carbon atoms, and an alkoxy group or an acyloxy group is (may have a substituent containing oxygen) The silicon atom content in the modified polyvinyl alcohol containing silicon atoms in the molecule obtained by the above method etc. is selected as appropriate depending on the usage form. You can, but
Usually 0.01 to 10 mol%, preferably 0.1 mol% in terms of silicon atom-containing olefinically unsaturated monomer units
~2.5 mol%.

The degree of polymerization of the modified polyvinylfluorcol containing silicon atoms in the molecule is not particularly limited, but is usually 250 to 3000, preferably 300 to 2000, particularly preferably 500 to 2.
000, and the degree of saponification of the vinyl acetate unit is similarly not particularly limited, but it is preferable to use one in the range of 70 to 99 mol%.

In the present invention, the colloidal silica and/or amorphous silica used together with the silicon-containing modified polyvinyl alcohol is industrially produced, and the colloidal silica is made by using water as a dispersion medium and ultrafine particles of silicic anhydride. It is a colloidal solution dispersed in water. The particle size is 10-1
00 mμ and a specific gravity of 1.1 to 1.3 are preferred. In this case, the colloidal solution preferably has a p+ value of 4 to 10.

Further, amorphous silica is industrially produced by a wet method or a gas phase method. -Primary particle size 10-30nm, secondary particle size 0
．． 5~10μ, oil absorption (JISK5101) 150~3
00ml/1009, apparent specific gravity (JIS K
6223) 0.1 to 0.39/ml and pH (5% suspension) 6 to 10 are preferred.

The blending ratio of silicon-containing polyvinyl alcohol and colloidal silica and/or amorphous silica is such that the total amount of silica is 0.5 parts by weight per 1 part by weight of silicon-containing polyvinyl alcohol.
05 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 0.2 to 2 parts by weight.

The coating layer according to the present invention may contain kaolin, calcined kaolin, talc, calcium carbonate, amorphous silica, barium sulfate, aluminum hydroxide, urea-formalin resin fine powder, polyethylene resin fine powder, polystyrene fine powder, if necessary. Inorganic and organic pigments such as powders, waxes such as polyethylene wax, carnauba wax, paraffin wax, microcrystalline wax, and fatty acid amides, metal soaps such as zinc stearate, calcium stearate, and surfactants may be added.

The coating amount of the coating layer according to the present invention is 0.1 to 59/m2,
Preferably it is 0.5-39/m2.

If the coating amount is less than this, the effect will be small, and if it is more than this, the photochromic sensitivity and heat fixing sensitivity will be significantly lowered, which is not preferable.

Preferred capsules in the present invention are those that prevent contact between substances inside and outside the capsule at room temperature due to the substance isolation effect of the microcapsule walls, and that permeability of substances increases only when heated above a certain temperature.

The permeation start temperature of this phenomenon can be freely controlled by appropriately selecting the capsule wall material, capsule core material, and additives. In this case, the permeation start temperature is
This corresponds to the glass transition temperature of the capsule wall.

In order to control the glass transition temperature specific to the capsule wall, it is necessary to change the type of capsule wall forming agent. Wall materials that can be used in the present invention include polyurethane, polyurea, polyamide, polyester, polycarbonate, etc., among which polyurethane and polyurea are particularly preferred.

The microcapsules used in the present invention are made by emulsifying a core material containing a photoimage-forming substance such as a leuco dye and a photooxidizing agent, and then forming a wall of a polymeric material around the emulsified oil droplets. In this case, a wall-forming agent is added to the inside of the oil droplet and/or to the outside of the oil droplet.

A high boiling point oil is used as the organic solvent for dissolving the above-mentioned photoimage-forming substance, and specifically, phosphoric acid ester, phthalic acid ester, acrylic acid ester, methacrylic acid ester, other carboxylic acid esters, fatty acid esters, Examples include alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes, diarylethanes, and chlorinated paraffins.

In the present invention, a low boiling point auxiliary solvent can also be added to the above organic solvent. Specific examples of co-solvents include ethyl acetate, Improvil acetate, butyl acetate, methylene chloride, cyclohexanone, and the like.

In order to stably form emulsified oil droplets, protective colloids and surfactants can be added to the aqueous phase.

In the present invention, the size of the microcapsules is set at a volume average of 2
It is preferably 0μ or less, more preferably 4μ or less.

In turn, the leuco dyes which constitute a component of the photoimageable materials of the present invention are reduced forms of dyes having one or two hydrogen atoms, with the removal of the hydrogen atom and in some cases the addition of additional electrons. Upon addition, color develops to form a dye. Since such leuco dyes are substantially colorless or have a weak color, when they oxidize and develop color, they serve as a means for forming a pattern. This oxidation is achieved in the present invention by the presence of at least one photooxidizing agent. This photooxidant is activated by light irradiation and reacts with the leuco dye to produce a colored image against a background of unirradiated and therefore unchanged material.

Leuco dyes that can readily develop color by the above mechanism include, for example, those described in US Pat. No. 3,445,234, which is hereby incorporated by reference.

[1] 7-minotriarylmethane, [2] 7-minoxanthene, (3) aminothioxanthin, (4) amino-9,10-dihydroacridine, (
5) 7minofenoxazine, (6) 7minofenothi7dine, (7) aminodihydrophenazine, (8) aminodiphenylmethane, (9) leucomendamine, 00) aminohydrocinnamic acid (cyanoethane, leucomethine), (11) hydrazine , θυ leucoindigoid dye, OJ amino-2,3-dihydro7anthraquinone, 0
Gradient tetrahalo p, p-biphenol, 05)2
-(p-Hydroxyphenyl)-4,5-diphenylimidazole, 0 phenethyl 7-niline.

Among these leuco forms, (1) to (9) form a base dye by losing one hydrogen atom, and 00) to 0 form a base dye by losing two hydrogen atoms.

Specifically, leuco crystal violet, tris-
(4-diethylamino-0-tolyl)-methane, bis-
(4-diethylamino-〇-tolyl)-phenylmethane, bis-(4-diethylamino-〇-tolyl)-thienyl-2-methane, bis-(2-chloro-4-diethyl 7
minophenyl)-phenylmethane, 2-(2-chlorophenyl)7 minnow 6-N, N-dibutylamino-9-(
2-methoxycarbonyl)-phenylxanthine, 2-
N,N-dibenzyl 7minor 6-N,N-diethylamino-9-(2-methoxycarbonyl)-phenylxanthine, benzo(a)-6-N, N-diethylamino-9-(2-methoxycarbonyl)-phenyl Xanthine, 2-(2-chlorophenyl)-7 minnow 6-N,N
-dibutylamino-9-(2-methylphenylcarboxamide)-phenylxanthine, 3,6-simethoxy9-(2-methoxycarbonyl)-phenylxanthine, 3,6-dinitoxyethyl-9-(2-methoxycarbonyl) )-phenylxanthine, benzoylleucomethylene blue 3,7-bis-diethylaminophenoxazine, and the like.

On the other hand, preferred photooxidizing agents that can be used in the photoimaging materials of the present invention are generally inert, but when exposed to actinic radiation such as visible light, ultraviolet light, infrared radiation, or X-rays, they cause the leuco dye to develop its color. It produces chemical species that oxidize to mold.

Typical photo-oxidizing agents include lophine dimer compounds such as 2,4°5-triarylimidazole dimer described in Japanese Patent Publication No. 62-39728 and Japanese Patent Publication No. 63-2099, and 2- Azide compounds such as 7-didobenzoxazole, benzoyl azide, 2-7-didobenzimidazole, U.S. Pat. No. 3,615,568
Pyridinium compounds such as 3'-ethyl-1-methoxy-2-pyridothiacyanine verchlorate, 1-methoxy-2-methylpyridinium-p-toluenesulfonate, N-promosuccinimide, tribromomethylphenylsulfone described in the No. , 2-trichloromethyl-5-(
p-butoxystyryl') -1°3.4-oxadiazole, organic halogen compounds such as 2,6-dydolychloromethyl-4-(p-methoxyphenyl)-triazine,
Examples include the 7 didobolimer described on page 55 of the lecture summary of the 1968 Spring Research Conference of the Photographic Society of Japan. Among these, lophine dimer compounds and organic halogen compounds are preferred, and the combination of both is optimal because high sensitivity can be achieved.

In producing the photoimage-forming material of the present invention, the leuco dye and the photooxidizing agent are preferably mixed in a molar ratio of 10:1 to 1:10, and more preferably in a molar ratio of 2:1 to 1:2. be.

The photoimage-forming material of the present invention can reliably obtain a stable image by performing a heat treatment after image formation by exposure. That is, the fixing mechanism of the photoimage-forming material of the present invention is such that the photooxidizing agent and the reducing agent come into contact with each other through the capsule wall by heating, so that even if the photooxidizing agent is subsequently activated, the reducing agent no longer acts. This is done by deactivating the oxidizing agent.

Such a reducing agent acts as a so-called free radical scavenger that traps the free radicals of the activated photooxidant.

Specific examples of the reducing agent include hydroquinone compounds and aminophenol compounds that have a hydroxyl group on a benzene ring and at least another hydroxyl group or an amino group at another position on the benzene ring, as described in US Pat. No. 3,042,515;
Examples thereof include the cyclic phenylhydrazide compound described in No. 39728, and further compounds selected from guanidine derivatives, fullylene diamine derivatives, and hydroxyamine derivatives. They can be used alone or in combination of two or more, but are not limited to these as long as they are reducing substances that have the function of acting on so-called oxidizing agents.

In the photoimage-forming material of the present invention, the reducing agent is preferably used by solid dispersion using a sand mill or the like, or by dissolving it in oil and emulsifying it.

The preferred amount of reducing agent is from 1 to 1 on a mole basis of the photooxidant component.
00 times the molar amount, more preferably 5 to 20 times the molar amount.

Image fixation in the present invention can be effectively achieved by bringing the photooxidizing agent and reducing agent into contact through the capsule wall by heating as described above, but a synergistic effect is expected by performing heating and pressurization at the same time. You can also do that. It is preferable to use a melting point depressant such as p-benzyloxyphenol or p-toluenesulfone 7mide in combination with this reducing agent because low-temperature fixing becomes possible.

In the present invention, there is no problem in adding a known sensitizer or antioxidant into the capsule.

The photoimage-forming material of the present invention is coated on a support as a dispersion of microcapsules containing such a leuco dye and a photooxidizing agent and a reducing agent, and is further coated with a colloidal material containing modified polyvinyl alcohol containing silicon atoms in the molecule. It can be made with a coating layer containing silica and/or amorphous silica.

A binder, pigment, etc. may be added to the microcapsules containing the leuco dye and photooxidizing agent and the dispersion of the reducing agent, and the coating amount is 3 to 309/m2 in terms of solid content.
Particularly preferred is 5 to 209/m2.

Suitable materials for the support include papers ranging from tissue paper to thick pole paper, regenerated cellulose, cellulose acetate, cellulose nitrate, polyethylene terephthalate, polyethylene, polyvinyl acetate, polymethyl methacrylate, polyvinyl chloride, and the like.

Methods for coating the support include air knife coating, curtain coating, slide coating, roller coating, dip coating, wire barcoding, blade coating, gravure coating, spin coating, or extrusion coating. etc., but are not limited to these.

Any convenient light source can be used in the present invention for activating the photooxidant and forming the image of the leuco dye. Conventional light sources include fluorescent lamps, mercury lamps, metal halide lamps, xenon lamps, tungsten lamps, and the like.

The photoimage-forming material of the present invention has excellent water resistance and is used as a photoimage-forming composition that prevents heat fixing roll staining and yellowing of the background area after heat fixation. Examples are shown below, but the present invention is not limited thereto. Note that "parts" indicating the amount added indicate "parts by weight."

"Example" Example 1 0icrystal violet 3 parts, 2. 2'-bis-(0-chlorophenyl)-4,4', 3 parts of 5°5'-tetraphenylbiimidazole, 0.6 part of tribromomethylphenylsulfone, 0° of 2,5-di-tert-octylhydroquinone 4 parts and 75% by weight of xylylene diisocyanate/trimethylolpropane adduct
24 parts of ethyl acetate solution was added to and dissolved in a mixed solvent of 22 parts of methylene chloride and 24 parts of tricresyl phosphate.

This solution was mixed with 63% polyvinyl alcohol 8% aqueous solution by weight.
emulsified and dispersed at 20°C until the average particle size was 1 μm.
An emulsion was obtained. Add 100 parts of water to the obtained emulsion,
Stirring was continued for 3 hours at 40°C. Thereafter, the mixture was returned to room temperature and filtered to obtain a capsule dispersion.

Next, 30 parts of 1-phenylpyrazolidin-3-one (phenidone A) was added to 1 part of a 4% by weight aqueous solution of polyvinyl alcohol.
The mixture was added to 50 parts and dispersed in a horizontal sand mill to obtain a phenidone A dispersion having an average particle size of 1 μm.

9 parts of the above capsule liquid and 6 parts of the phenidone 8 dispersion were mixed and coated on high-quality paper (basis weight 769/m2) with a coating rod so that the solid coating amount was 109/m2.
It was dried at C.

On this photosensitive coloring layer, a coating liquid prepared as described below was applied to a coating amount of 2.5;+/m2 in terms of solid content, dried, and calendered. An imaging material was obtained.

Preparation of coating layer coating liquid 10% silicon-modified polyvinyl alcohol (copolymer of vinyltrimethoxysilane and vinyl acetate, containing 0.5 mol% silicon as vinyl silane units, degree of saponification of vinyl acetate units 98.3%, degree of polymerization 500) aqueous solution
70 parts 20% colloidal silica (Snowtex C
(manufactured by Nissan Chemical) 20 parts 50% kaolin dispersion 10 parts 21% paraffin wax (average carbon number 30) dispersion
2.5 parts 30% zinc stearate dispersion
1.5 parts 2% perfluoroalkyl carboxylate (Mega Futsuk F120 manufactured by Dainippon Ink) aqueous solution 2.5
1.2 parts or more of a 2% aqueous solution of 2-ethylhexyl sulfosuccinate were mixed to prepare a coating liquid.

Example 2 A photoimage forming material was obtained in the same manner as in Example 1 except that the formulation of the coating layer coating liquid was changed as follows.

5% silicon-modified polyvinyl alcohol (copolymer of vinyltrimethoxysilane and vinyl acetate, containing 0.5 mol% silicon as vinyl silane units, degree of saponification of vinyl acetate units 98.5%, degree of polymerization 1000) aqueous solution
50 parts 20% stearic acid 7amide dispersion 2.5
Part 25% polyamide resin aqueous solution 5 parts 20%
Calcium-treated amorphous silica (oil absorption 150m1/10
09) 10 parts 50% calcium carbonate dispersion 10 parts 30% zinc stearate dispersion
1.5 parts or more were mixed to prepare a coating layer coating liquid.

Comparative Example 1 A photoimage forming material was obtained in the same manner as in Example 1 except that the coating layer was not provided.

The photoimage forming materials obtained in Examples and Comparative Examples were tested as follows. The results are shown in Table 1.

(1) Image Density A fresh sample was irradiated with light through a line drawing original using a jet light (ultra-high pressure mercury lamp, manufactured by Oak ■), and the image density of the exposed area was measured with a Macbeth reflection densitometer.

(2) Heat fixing roll stain 120 sheets of 50 samples (A4 size) after the above image formation
The roll was passed through a heated roller at a temperature of 450 mm/min, and the state of roll staining was visually determined.

(3) Yellowing of the background After irradiating the above heat-fixed sample with a fluorescent lamp of 200 lux for 10 consecutive days, the yellow density of the background was measured using a Macbeth reflection densitometer. It was compared with the yellow density of the background.

(4) Water Resistance 5 ml of water was dropped onto the surface of the sample after the above heat fixing, and the sample was rubbed 10 times with a finger to determine how much of the photoimage forming layer was peeled off.

Table 1 "Effects of the Invention" The photoimage-forming materials of Examples 1 and 2 of the present invention had no change in image density compared to photoimage-forming materials that did not have a coating layer.
It can be seen that the water resistance is excellent, and there is little staining on the heat fixing roll and yellowing of the background after heat fixing.

Claims (1)

[Claims] In a photoimage-forming material in which a coating layer is formed on a support, the coating layer is formed on a support, and the coating layer includes microcapsules containing both a leuco dye capable of oxidative color development and a photooxidizing agent, and a reducing agent as essential components. A photoimage-forming material comprising a coating layer containing modified polyvinyl alcohol containing silicon atoms and colloidal silica and/or amorphous silica.