JP2003255595A - Decolorizable image forming material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decolorizable image forming material by which a sharp image can be formed and a high quality and favorable state can be obtained. <P>SOLUTION: The decolorizable image forming material comprises a coloring compound, a developing agent, a binder resin (1) and a non-polar resin (decolorizing agent resin) (3) existing in a phase separation state in the binder resin (1). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming material which can be used for printers, copiers, fax machines, thermal transfer recording, writing instruments, printing, etc. to form images and which can be erased by controlling heat history or contact with a solvent. Regarding

[0002]

2. Description of the Related Art Forest protection is an important condition for protecting the global environment and suppressing the greenhouse effect of CO ₂ . In order to maintain new forests to a minimum and to maintain a balance with reforestation including afforestation, it is important to efficiently use the paper resources that we already have. It has become a challenge. The current reuse of paper resources is "recycling" in which the paper fibers that have undergone the deinking process that peels off the image-forming material are used again for different purposes by filtering them back into poor quality paper, which causes problems such as high cost of the deinking process and waste liquid. It has been pointed out that there is a possibility of new environmental pollution due to the treatment.

Up to now, it has been practiced to use a poppy rubber for a pencil and a correction liquid for a writing ink to correct an image and reuse the paper. Further, recently, special paper rewritable paper for the purpose of reusing hard copy paper has been proposed. Here, “reuse”, in which deterioration of paper quality is prevented as much as possible and used multiple times for the same purpose, is a different concept from “recycling”, which is used for other purposes while reducing paper quality, and is seen from the perspective of protecting paper resources. It is a more important concept. If effective “reuse” is performed as a step before the final “recycling”, it is possible to minimize the waste of new paper resources.

The present inventors have already paid attention to the fact that when the interaction between the color developable compound and the color developing agent increases, the state becomes a colored state, and when the interaction decreases, the state becomes a color disappearing state. By adding a decolorizing agent that newly captures the color developing agent to the composition system containing the color developing agent, the color-developed state is stable at a temperature near room temperature, and by treatment with heat or a solvent,
An image forming material capable of fixing the decolored state for a long time at a practical temperature (for example, JP-A-10-88046, JP-A-11-212295, and JP-A-11-272133).
Image) and image erasing process (for example, Japanese Unexamined Patent Application Publication No. H11-11
No. 268409) is proposed. These image-forming materials have high stability in the colored / decolored state of the image, and also have high safety, and are compatible with all electrophotographic toners, liquid inks, ink ribbons, and writing instruments. Further, it has an advantage over the conventional technology that large-scale erasing processing is possible. Therefore, by using these image forming materials, it is possible to realize an effective paper reuse technology that replaces the current recycling technology, and it is possible to significantly reduce paper dust, which has a great effect on resource saving.

Further, in the process of studying the improvement of the characteristics of the image erasable image forming material, the present inventors have found that the image recording medium is a polar polymer such as paper and has the ability to capture the color developer and the image formation. When the binder of the material is a non-polar material having the property of increasing the dye capture amount by the temperature rise or the contact with the solvent, the developer capturing type decolorizer may be added a few times without adding it to the image forming material. Then, it was discovered that the image can be decolored, and an image forming material containing no decolorizing agent for capturing the color developing agent and a decoloring method thereof were also developed (Japanese Patent Laid-Open No. 2000-28).
4520). The image forming material of this composition is restricted by the image recording medium, but has a merit that the resin content can be increased and therefore the offset resistance of the toner can be improved.

However, as the development of this composition system proceeded, the problems to be further improved became clear. The first problem is the limit of contrast between coloring and erasing in thermal erasing. In the above composition system, both coloring and decoloring are determined by the equilibrium of the actions of the dye and the developer in the softened binder. Therefore, the contrast between coloring and erasing is affected by the temperature dependence of the equilibrium constant in the binder. Specifically, the limit value of contrast is determined by the manufacturing process temperature of the image forming material and the erasing process temperature. The second problem is the problem of "recurrent color". Re-coloring is a phenomenon in which an image that has once been decolorized develops again on or near the image, and is particularly likely to occur in the decolorization process using a solvent. This phenomenon is caused by the re-association of the separated dye and developer.
This occurs because the interaction between the two is restored, resulting in defective erasing such as "image flow".

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an erasable image forming material which can form a clear image and can obtain an erasable state with good quality.

[0008]

An image erasable image forming material according to one embodiment of the present invention comprises a color developing compound, a color developing agent, and
It contains a binder resin and a non-polar resin that coexists in the binder resin in a phase-separated state.

An image erasable image forming material according to another embodiment of the present invention contains a color developable compound, a color developer, and a polymer alloy having a phase separation structure.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a decolorizable toner according to an embodiment of the present invention. In FIG. 1, a binder resin 1 contains a color-forming material 2 in which a color-developing compound (leuco dye) and a color developer are associated with each other, and a decolorizer resin 3 (for example, an oligomer crystal) phase-separated from the binder resin 1. In addition, the release agent 4, the charge control agent 5 (CCA), and a small amount of a molecular color-developing compound and a developer are dispersed.

In the decolorizable image-forming material according to the exemplary embodiment of the present invention, the non-polar resin coexisting in the binder resin in a phase-separated state, or the non-polar resin constituting the minority phase of the phase-separated polymer alloy is It has a property of capturing (compatibility) with a color-forming compound (leuco dye). Hereinafter, such a non-polar resin is referred to as a decolorizer resin. In this specification,
"Compatible" means that the color-forming compound molecule can diffuse into the decolorizing agent resin which is in a heat-softened state or a solvent-swelled state. In addition, the term decolorizer resin is used because it causes steric hindrance or interaction with the color-forming compound molecule trapped inside it, making it difficult to diffuse and leave again, thereby improving the decoloring state. This is because it can be saved. In the decolorizable image forming material containing such decoloring agent resin, coloring and decoloring occur according to the following principles.

The decoloring agent resin is in a phase-separated state with the binder (or the main component of the polymer alloy) at the manufacturing process temperature of the image-forming material, and hardly captures (compatibility) the color-forming compound, so that the color-forming property is improved. Increases the interaction between the compound and the developer to develop color. On the other hand, the decolorizing agent resin is compatible with the binder (or the main component of the polymer alloy) at the decoloring process temperature and exhibits the property of capturing (compatibility) with the color developable compound. Decreases the interaction by reducing the interaction with colorants. At this time, the equilibrium between the color-developing compound and the color-developing agent is biased to a more separated state at the same time when the compatibility is started. As a result, the coloring / decoloring contrast is improved. In addition, the decolorizer resin has a merit that it is possible to selectively capture the color-developing compound and spatially separate it from the developer that moves into the image recording medium (paper). The specific material of the decolorizable resin will be described later.

Various components contained in the erasable image forming material according to the embodiment of the present invention will be described below.

The color-forming compound (leuco dye) used in the embodiment of the present invention includes leuco auramines, diaryl phthalides, polyaryl carbinols, acyl auramines, aryl auramines, rhodamine B. Lactams, indolines, spiropyrans,
Examples thereof include electron-donating organic substances such as fluoranes. Specifically, crystal violet lactone (CVL),
Malachite green lactone, 2-anilino-6- (N
-Cyclohexyl-N-methylamino) -3-methylfluorane, 2-anilino-3-methyl-6- (N-methyl-N-propylamino) fluorane, 3- [4- (4
-Phenylaminophenyl) aminophenyl] amino-
6-methyl-7-chlorofluorane, 2-anilino-6
-(N-methyl-N-isobutylamino) -3-methylfluorane, 2-anilino-6- (dibutylamino)-
3-methylfluorane, 3-chloro-6- (cyclohexylamino) fluorane, 2-chloro-6- (diethylamino) fluorane, 7- (N, N-dibenzylamino) -3- (N, N-diethylamino) Fluoran,
3,6-bis (diethylamino) fluorane-γ-
(4'-Nitro) anilinolactam, 3-diethylaminobenzo [a] -fluorane, 3-diethylamino-6
-Methyl-7-aminofluorane, 3-diethylamino-7-xylidinofluorane, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-
Methylindol-3-yl) -4-azaphthalide, 3
-(4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3-diethylamino-7-chloroanilinofluorane, 3-diethylamino-7,8-benzofluorane, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,6-dimethylethoxyfluorane,
3-diethylamino-6-methoxy-7-aminofluorane, DEPM, ATP, ETAC, 2- (2-chloroanilino) -6-dibutylaminofluorane, crystal violet carbinol, malachite green carbinol, N- (2, 3-dichlorophenyl) leuco auramine, N-benzoyl auramine, rhodamine B lactam, N-acetyl auramine, N-phenyl auramine, 2- (phenyliminoethanedilidene) -3,3
-Dimethylindoline, N-3,3-trimethylindolinobenzospiropyran, 8'-methoxy-N-3,3
-Trimethylindolinobenzospiropyran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
Diethylamino-7-methoxyfluorane, 3-diethylamino-6-benzyloxyfluorane, 1,2-benz-6-diethylaminofluorane, 3,6-di-p
-Toluidino-4,5-dimethylfluorane, phenylhydrazide-γ-lactam, 3-amino-5-methylfluorane and the like can be mentioned. These may be used alone or in combination of two or more. By appropriately selecting a color-forming compound, various colored states can be obtained, and thus color compatibility is easy. Among these, triphenylmethane type, fluorane type, and phenyl-indole-phthalide type are particularly preferable.

Examples of the color developer used in the embodiment of the present invention include phenols, phenol metal salts, carboxylic acid metal salts, benzophenones, sulfonic acids, sulfonates, phosphoric acids, phosphoric acid metal salts, and acidic phosphoric acid. Examples thereof include esters, acidic phosphoric acid ester metal salts, phosphorous acid, and phosphorous metal salts. Specifically, gallic acid, and gallic acid such as methyl gallate, ethyl gallate, n-propyl gallate, i-propyl gallate, and butyl gallate. Ester, dihydroxybenzoic acid such as 2,3-dihydroxybenzoic acid and methyl 3,5-dihydroxybenzoate and its ester, 2,4-dihydroxyacetophenone, 2,5-dihydroxyacetophenone, 2,6-dihydroxyacetophenone, 3, 5-
Hydroxyacetophenones such as dihydroxyacetophenone, 2,3,4-trihydroxyacetophenone, 2,4-dihydroxybenzophenone, 4,4′-
Dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone Hydroxybenzophenones such as
Biphenols such as 2,4′-biphenol and 4,4′-biphenol, 4-[(4-hydroxyphenyl)
Methyl] -1,2,3-benzenetriol, 4-
[(3,5-Dimethyl-4-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4,6-bis [(3,5-dimethyl-4-hydroxyphenyl) methyl] -1,2. 3-benzenetriol, 4,4'-
[1,4-phenylenebis (1-methylethylidene) bis (benzene-1,2,3-triol)], 4,4 '
-[1,4-phenylenebis (1-methylethylidene)
Bis (1,2-benzenediol)], 4,4 ', 4''
-Ethylidene trisphenol, 4,4 '-(1-methylethylidene) bisphenol, methylene tris-p-
Examples include polyphenols such as cresol. These can be used alone or in combination of two or more. Among these, those of gallic acid ester type, hydroxybenzophenone type and hydroxyacetophenone type are particularly preferable.

The binder resin used in the embodiment of the present invention will be described. As a binder resin,
Those containing a large amount of polar groups (acryl group, carbonyl group, ether group, ketone group, hydroxyl group, amide group, etc.) that contribute to hydrogen bonding are not suitable. The reason is that the resin containing a large amount of polar groups has high compatibility with the phenolic color developer, and the equilibrium between the color developable compound (leuco dye) and the color developer is separated (decolored) in the kneading process of the manufacturing process. This is because the color density of the image forming material is reduced because the color is biased toward the side. For example, when a decolorizable toner containing a fluorane-based leuco dye and a gallic acid ester is prepared by using a styrene butyl acrylate resin as a binder resin, the content of butyl acrylate in the binder resin is preferably 10 wt% or less. . Therefore, the binder resin is preferably a nonpolar resin or a resin having a small polarity.

The non-polar resin used as the binder resin is a styrene resin (specific examples of styrene monomers are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylsterene,
2,4-dimethylstyrene, pn-butylstyrene,
p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, Pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenyl styrene,
p-chlorostyrene, 3,4-dichlorostyrene, etc.) and olefin resins (specific examples of the olefin monomer are ethylene, propylene, methylpentene, butadiene, norbornene derivatives, etc.) and the like. These copolymers can also be used as the nonpolar resin.

As the resin having a small polarity used as the binder resin, a copolymer of the above non-polar monomer and a small amount of a polar monomer can be mentioned. As described above, the content of the polar monomer is preferably 10 wt%. As the polar monomer copolymerizable with the non-polar monomer, an acrylic monomer such as n-butyl methacrylate,
Isobutyl methacrylate, ethyl acrylate, n-
Butyl acrylate, methyl methacrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminopropyl acrylate, 2-ethylhexyl acrylate, butyl acrylate-N- (ethoxymethyl)
Acrylamide, ethylene glycol methacrylate,
4-hexafluorobutyl methacrylate and the like can be mentioned. One of these acrylic monomers may be used for copolymerization, or two or more of them may be used for copolymerization. Other polar monomers copolymerizable with the non-polar monomer include vinyl monomers such as vinyl acetate, vinyl propionate, methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether and isobutyl ether.

The dye-capture type decolorizer resin used in the embodiment of the present invention will be described. In the embodiment of the present invention, a triphenylmethane-based or fluoran-based coloring compound (leuco dye) and a gallic ester-based or hydroxybenzophenone-based developer are used. A non-polar material having a highly compatible benzene skeleton is suitable. Specifically, styrene or a styrene derivative (specific examples of styrene-based monomers are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4
-Dimethylstyrene etc.) homopolymers or copolymers of oligomers or polymers. Also, a copolymer of styrene or a styrene derivative and olefin can be used. More specifically, styrene / α-
Examples include methyl styrene oligomer. Examples of the phase-separated polymer alloy containing a minority phase nonpolar resin that functions as a decolorant resin include styrene / butadiene rubber.

However, it is preferable that the decoloring agent resin is appropriately selected by comparing thermal property values (particularly viscoelasticity) with the binder resin used. Specifically, it is preferable that the decoloring agent resin has thermal characteristics that it has a high glass transition point and a low softening point as compared with the binder resin. If the binder resin and the decoloring agent resin in such a combination are selected, the decoloring agent resin remains phase-separated in the binder resin during the kneading process of the manufacturing process, and both are completely compatible in the decoloring process. Can be made.

Table 1 shows polystyrene SB150 manufactured by Sanyo Kasei Co., Ltd., which is used as a binder resin, and three kinds of styrene-based oligomers (F, manufactured by Mitsui Chemicals, Inc.) which are candidate materials for the decolorizing agent resin.
The physical properties of TR0140, FTR2140, FMR0150) are shown collectively.

[0022]

[Table 1]

The above three types of styrene-based oligomers (FT
Among R0140, FTR2140, and FMR0150), FTR2140 has the largest difference in the glass transition point (plus 27 ° C) and the largest difference in the softening point (minus 7 ° C) as compared with the binder resin. Therefore, FTR21
40 is estimated to be the best decolorizer resin. As a result of actually evaluating the toner prepared by kneading these materials, FT
The best color development and decoloring performance was obtained when R2140 was used. The evaluation data is shown in the section of Examples.

Further, a preliminarily prepared multiphase polymer alloy, that is, a polymer alloy having a phase-separated structure can be used in place of the binder resin containing the phase-separated decolorizer resin. Typical polymer alloys include styrene-butadiene rubber having a structure in which a polystyrene phase and a butadiene rubber phase are separated, styrene-ethylene-propylene terpolymer, styrene- (ethylene-butylene) -styrene, propylene-ethylene-propylene. Rubber, propylene-butadiene rubber, propylene-styrene-butadiene rubber, α-methylstyrene
Examples thereof include styrene-butadiene rubber and styrene-phenylene ether. When an image forming material is manufactured using these polymer alloys having a multiphase structure, the conditions are set such that the phase separation state of the resin is maintained during kneading.

The charge control agent used in the decolorizable toner is preferably colorless so that no color remains when decolored. Among the commonly used charge control agents, as a negative charge control agent, Orient Chemical E-84 (zinc salicylate compound), Nippon Kayaku's N-1, N-2, N-3 (all phenolic compounds), Fujikura FCA-1001 from Kasei
N (styrene-sulfonic acid type resin) or the like is used as a positive charge control agent by TP-302 (CAS # 116 of Hodogaya Chemical Co., Ltd.).
810-46-9), TP-415 (Id. 117342-).
25-2), P-51 (quaternary amine compound) of Orient Chemistry, AFP-B (polyamine oligomer), FCA-201PB (styrene / acrylic quaternary ammonium salt-based resin) of Fujikura Kasei, and the like. Also, acrylic fine particles can be used as a charge control agent. For example, as the negative charge control agent, acrylic fine particles MP-1451, MP-2200, MP-1000 manufactured by Soken Kagaku,
Styrene / acrylic copolymer fine particles MP-2701 and the like can be used as positive charge control agents by Soken Chemical Co., Ltd. acrylic fine particle MP-2701 and styrene / acrylic copolymer fine particles M.
P-5500 etc. are mentioned.

The decolorizable toner may be mixed with waxes or the like for controlling the fixing property, if necessary.
The waxes preferably contain components such as higher alcohols, higher ketones and higher aliphatic esters. The waxes preferably have an acid value of 10 or less. The waxes preferably have a weight average molecular weight of 10 ² to 10 ⁴ . If the weight average molecular weight is within the above range, low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polybutylene, low molecular weight polyalkane and the like can be used. The amount of waxes added is preferably 0.5 to 10 parts by weight.

[0027]

EXAMPLES Example 1 3- (4-Dimethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 3.56 wt. Parts, 2 parts by weight of n-propyl gallate as a developer, 2 parts by weight of polypropylene wax as a wax component, and 1 part by weight of a charge control agent (LR-147, Japan Carlit Co., Ltd.) were prepared. Also, the molecular weight of the binder resin is 6500
No. 0 polystyrene (SB150 manufactured by Sanyo Kasei) and styrene / α-methylstyrene oligomer (FTR2140) were prepared as the decolorizing resin, and the total amount of the resin was 91.44.
It was weighed so as to be a weight part. The blending ratio of the binder resin and the decolorizer resin is 100: 0 (blending SB150 alone), 80:20, and 0: 100 (FTR2140).
Was formulated independently). These raw materials were sufficiently kneaded and dispersed using a closed kneader, and then the kneaded product was pulverized and classified to obtain a powder having an average particle diameter of about 10 μm.
Hydrophobic silica (1 wt%) was externally added to the obtained powder to prepare a blue electrophotographic toner.

Using these toners, copy paper (NEUSIEDL
An image evaluation pattern having a plurality of evaluation areas (solid images) with different image densities was transferred onto an ER neutral paper 500BLATT. Minolta color difference meter (CR300)
Was used to measure the initial reflection density (image density) of the image.

Next, the image was heat-erased using a constant temperature dryer. Decolorization temperature is 120 ℃, 130 ℃ or 140 ℃
And a stack of 200 sheets of paper was erased in 2 hours. 20
Of the stack of 0 sheets, the 10th, 100th and 1st from the top
The 90th sheet was taken out as a sample for measurement.
The reflection density (afterimage density) of the image after thermal erasing was measured again using a color difference meter (CR300) manufactured by Minolta.

The color development / decolorization contrast was evaluated as follows. Image density: Dp = [initial reflection density of solid image]-[blank paper reflection density] Afterimage density: Da = [reflection density of solid image after thermal erasing]-
[Blank part reflection density] Coloring / decoloring contrast: C = Dp / Da.

FIG. 2 shows the result of a thermal erasing test conducted at 130 ° C. for 2 hours. In FIG. 2, the horizontal axis represents the initial image density and the vertical axis represents the afterimage density after erasing. When a straight line passing through the origin and passing through each plot is created, the representative value of the coloring / decoloring contrast is represented by the reciprocal of the inclination of the straight line. Figure 2
From the binder resin (SB150) and the decolorizer resin (F
It can be seen that the toner in which the compounding ratio of TR2140) is 80:20 shows the best coloring / decoloring contrast.

In FIG. 3, the toner of each composition is used in the same manner as described above, and after transferring the image evaluation pattern on the paper, 120
When the color is erased at the set temperature of ℃, 130 ℃, 140 ℃,
Indicates the contrast value of coloring / decoloring. From FIG. 3 as well, SB1
It can be seen that the toner in which the compounding ratio of 50 and FTR2140 is 80:20 shows the best color development / decoloration contrast. By using the two kinds of resins together, it is possible to obtain good characteristic values that do not fall within the range between the color-developing / decoloring contrast characteristic values exhibited by each of the individual resins. From this result, it can be said that the two types of resins have a synergistic effect that affects the coloring / decoloring contrast characteristics.

Here, FTR2140 which is a decolorant resin
The reason why the color-developing / decoloring contrast becomes low when is used alone will be described. Coloring / decoloring contrast is
It is the ratio of the initial image density and the afterimage density after erasing. The former depends on the manufacturing process temperature of the image forming material, and the latter depends on the erasing process temperature. Since FTR2140 has a high glass transition point, the temperature of the toner manufacturing process becomes high.
For this reason, dissociation of the color-developing compound and the color-developing agent in the matrix of the binder resin progresses, and as a result, the color-developing density decreases. Even with the same transfer amount, since the toner color development rate is low, the initial image density is relatively low and the color development / decoloration contrast is low.

Next, the evaluation results of solvent decolorization will be shown. The erasing test is performed in I & J F
ISNER Inc. Stationery parts (FV-0200)
An erasing solvent was put in the solution to evaluate the afterimage after erasing. Acetone was used as the decolorizing solvent. The toner containing SB150 alone had a coloring / decoloring contrast of 27.
With the toner containing B150 and FTR2140 in a ratio of 80:20, the contrast of color development / decolorization was improved to 81.
However, with toner containing FTR2140 alone, SB1
Compared with the toner in which the compounding ratio of 50 and FTR2140 was 80:20, the color developing / erasing contrast was equal to or higher.

Example 2 3.5 (part by weight) of 3- (4-dimethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide as a color-developing compound Then, 2 parts by weight of n-propyl gallate as a developer, 2 parts by weight of polypropylene wax as a wax component, and 1 part by weight of a charge control material (LR-147, Japan Carlit Co., Ltd.) were prepared. In addition, the binder resin has a molecular weight of 6500.
No. 0 polystyrene (SB150 manufactured by Sanyo Kasei) is used as a decolorizing agent resin, and three types of styrene-based oligomers (F manufactured by Mitsui Chemicals, Inc.)
TR0140, FTR2140, or FMR015
0) was weighed so that the total amount of the resin was 91.44 parts by weight. The mixing ratio of binder resin and decolorizer resin is 8
It was fixed at 0:20. After thoroughly kneading and dispersing these raw materials using a closed kneader, the kneaded product is crushed and
The powder was classified to obtain a powder having an average particle size of about 10 μm. Hydrophobic silica (1 wt%) was externally added to the obtained powder to prepare a blue electrophotographic toner.

For comparison, a toner was prepared by using SB150 alone as a binder resin.

In the same manner as in Example 1, the coloring / decoloring contrast was evaluated. In Figure 4, 120 ℃, 130 ℃, 14
The coloring / decoloring contrast value of each toner that has been decolored at the set temperature of 0 ° C. is shown. Compared to the toner containing SB150 alone, the toner containing SB150 and FTR2140 at 80:20 has a higher color development / erasing contrast in the entire temperature range.
In contrast, SB150 and FTR0140 are 80: 2
The toner containing 0 has a high coloring / decoloring contrast on the low temperature side, but no significant difference is observed at 140 ° C. From this, it is understood that the addition effect of FTR0140 is inferior to that of FTR2140. In addition, SB150 and FMR01
The toner containing 50:80:20 showed no significant improvement. Therefore, it can be seen that FTR2140 has the best characteristics among the above three types of decoloring agent resins. This result supports the above-mentioned guideline for selecting the decolorizer resin.

Example 3 3.56 parts by weight of 3- (4-dimethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide as a color-developing compound , 2 parts by weight of n-propyl gallate as a developer, 2 parts by weight of polypropylene wax as a wax component, 1 part by weight of a charge control material (Japan Carlit Co., Ltd., LR-147),
Styrene-butadiene rubber resin (GOOD YEAR CHEMICAL, Pli
91.44 parts by weight of one resin: PTR-7716). These raw materials were sufficiently kneaded and dispersed using a closed kneader, and then the kneaded product was pulverized and classified to obtain a powder having an average particle diameter of about 10 μm. Hydrophobic silica (1 wt%) was externally added to the obtained powder to prepare a blue electrophotographic toner.

For comparison, a toner was prepared by using SB150 alone as a binder resin.

In the same manner as in Example 1, the coloring / decoloring contrast was evaluated. In Figure 5, 120 ℃, 130 ℃, 14
The coloring / decoloring contrast value of each toner that has been decolored at the set temperature of 0 ° C. is shown. Styrene-butadiene rubber resin (PT
The toner containing R-7716) develops color in a temperature range of 130 ° C. or higher as compared with the toner containing SB150 alone.
It can be seen that the decolorization contrast is significantly improved.

[0041]

INDUSTRIAL APPLICABILITY As described above, the image erasable image forming material according to the present invention can improve the image erasing property which is important for the reuse of paper, and therefore has great industrial value.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a decolorizable toner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a result of thermally erasing the toner in Example 1 at 130 ° C. for 2 hours.

FIG. 3 shows the toner used in Example 1 at 120 ° C. and 130 ° C.
The figure which shows the coloring / decoloring contrast value at the time of decoloring at the setting temperature of ℃, 140 ℃.

FIG. 4 shows the toner used in Example 2 at 120 ° C. and 130 ° C.
The figure which shows the coloring / decoloring contrast value at the time of decoloring at the setting temperature of ℃, 140 ℃.

FIG. 5 shows the toner in Example 3 at 120 ° C. and 130 ° C.
The figure which shows the coloring / decoloring contrast value at the time of decoloring at the setting temperature of ℃, 140 ℃.

[Explanation of symbols]

1 ... Binder resin 2 ... Coloring material 3 Decolorant resin 4 Release agent 5 ... Charge control agent (CCA)

Claims (5)

[Claims] 1. A color-erasable image-forming material comprising a color-developing compound, a color-developing agent, a binder resin, and a nonpolar resin that coexists in the binder resin in a phase-separated state. . 2. The nonpolar resin is selected from the group consisting of homopolymers of styrene or styrene derivatives and copolymers thereof, and copolymers of styrene or styrene derivatives and olefins. The decolorizable image forming material according to claim 1. 3. The non-polar resin is a styrene / α-methylstyrene oligomer.
Alternatively, the decolorizable image-forming material as described in 2 above. 4. A decolorizable image-forming material comprising a color developable compound, a color developer, and a polymer alloy having a phase separation structure. 5. The decolorizable image forming material according to claim 4, wherein the polymer alloy is styrene / butadiene rubber.