JP2804293B2 - Recording agent - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material for an office word processor and a hard copy device for a personal computer, and more particularly to a recording material for a recording device capable of increasing the density of a recorded image and performing gradation recording.

[Prior art] Regarding the phenomenon of gel structure formation and structural destruction due to electrification of polyvinyl alcohol-borate gel "Study on electrodeposition mechanism of polyvinyl alcohol" Kolloi
dn, zh, 46 , 771 (1984). Japanese Patent Application Laid-Open No. Sho 63-3027 discloses a recording method utilizing the destruction of the crosslinked structure observed in the polyvinyl alcohol-boric acid gel at the anode due to energization.
It is disclosed in 9 mag. This is a flowable ink in which a coloring material is dispersed in a structure in which a hydrophilic polymer is crosslinked with borate ions. The crosslinked structure is destroyed at the anode by applying electricity, and this is transferred to an intermediate transfer medium or a transfer medium such as a film. Transferred to
The image is formed by further transferring the image onto plain paper, and is a recording method with low running cost and low energy. With this method, the running cost, which is a disadvantage of the conventional thermal transfer method, can be reduced, and color printing can be easily performed.

Further, in order to improve the temporal stability of the fluid ink,
Regarding image recording inks added with polyhydric alcohols, etc.
It is disclosed in JP-A-64-69679.

[Problems to be Solved by the Invention] However, the conventional fluid ink requires the use of an intermediate transfer medium or the like, and cannot be directly transferred to plain paper. In addition, there is a problem that background contamination is likely to occur even when an intermediate transfer medium is used. To solve this problem, the present inventors have previously filed an application for a substantially non-flowable recording agent and a recording method using the same. did.

However, even in such a non-fluid or high-viscosity recording agent, water is mainly used as a liquid medium,
The change in the characteristics of the recording agent due to the evaporation of water over time and the change in the characteristics of the recording agent due to the release of water in the transfer step become problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording agent that eliminates a characteristic change due to moisture evaporation when a recording apparatus is not operated, and that can control an adhesion characteristic by energization. It is another object of the present invention to provide a recording agent with less deterioration in image quality such as background stain and tailing.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that organic solvents having a high moisturizing property and a low vapor pressure, which are conventionally known as wetting agents for aqueous inks, are used. Attempt to add was recorded one organic solvent selected from the group of polyhydric alcohols and polyhydric alcohol alkyl ethers and at least one organic solvent selected from the group of nitrogen-containing heterocyclic compounds and alkanolamines 5 to 40 in total
By containing it by weight, it has become possible to provide a recording agent capable of controlling the change in adhesion due to energization without deteriorating the recording characteristics over time.

According to the study of the present inventors, a cross-linked structure composed of a hydrophilic polymer whose cross-linking structure changes upon electrification and the adhesion property to a transfer medium changes, interacts with water as a solvent in forming the cross-linking structure. The effect was presumed to be related, and it was confirmed that the crosslinked structure was changed by the addition of the organic solvent.

For example, when a crosslinked structure is obtained with borate ions using polyvinyl alcohol as a hydrophilic polymer, when a polyhydric alcohol such as ethylene glycol is added, the fluidity becomes higher than in the case of no addition, and the content is higher. If too much, it becomes difficult to form a crosslinked structure.

In contrast, 1,3-dimethylimidazolidinone, N-
When a nitrogen-containing heterocyclic compound such as methyl-2-pyrrolidone is added, the crosslinked structure is strengthened and the fluidity is lowered, and the non-flowable gel has high strength. However, there is a problem that the adhesion becomes difficult or the adhesion property deteriorates.

Therefore, a combined use of a wetting agent for weakening the cross-linking structure such as a polyhydric alcohol and a wetting agent for strengthening the cross-linking structure such as a nitrogen-containing heterocyclic compound is included in a total amount of 5 to 40% by weight of the recording agent. It is possible to obtain a recording agent having a crosslinked structure with a small amount of coloring material and sufficient holding power.

That is, the present invention relates to a recording agent whose cross-linking structure is destroyed by application of thermal energy and an electrochemical reaction, and which can control the adhesion characteristics to a transfer-receiving medium, wherein the cross-linking structure comprising a hydrophilic polymer is used. In a recording agent comprising a substance, a colorant, water and a wetting agent, the wetting agent is at least one organic solvent selected from the group of polyhydric alcohol alkyl ethers, and a nitrogen-containing heterocyclic compound, selected from the group of alkanolamines. A recording agent characterized by containing at least one organic solvent in a total amount of 5 to 40% by weight based on the recording agent.

As described above, the recording agent of the present invention is basically composed of a crosslinked structural material composed of a hydrophilic polymer, a coloring material, water and a wetting agent.

As the hydrophilic polymer used in the recording agent of the present invention,
Examples include polysaccharides such as locust bean gum, guar gum, and pectin; electrolyte polysaccharides such as carrageenan; and synthetic polymers having a hydroxyl group such as polyvinyl alcohol. The borate ions which crosslink these are obtained by dissolving borate such as boric acid and borax in water. The hydrophilic polymer is used alone or in combination of two or more. The content in the recording agent depends on the molecular weight and the solution viscosity, but it is usually preferable to use 1 to 20% by weight. The amount of borate ion to be cross-linked is used in an amount necessary to maintain at least the non-flowability of the recording agent, which does not reach the gel melting point at room temperature. Here, the peak corresponding to the gel melting in the differential thermal analysis of the recording agent that has not reached the gel melting point exists at least at 25 ° C. or higher. In particular,
It is preferable to add boric acid or borax as a borate ion source in an amount equal to or more than 1/4 equivalent of the number of crosslinkable hydroxyl groups of the hydrophilic polymer. The degree of crosslinking increases and the gel strength increases. In the case of boric acid, gelation can be effectively performed by simultaneously adding an alkali hydroxide.

As described above, the wetting agent used in the recording agent of the present invention comprises at least one selected from the group consisting of (A) a polyhydric alcohol and a polyhydric alcohol alkyl ether, and (B) a nitrogen-containing heterocyclic compound and an alkanol. It is used in combination with at least one selected from amines.

Among them, the addition of the polyhydric alcohol as the component (A) has an effect of weakening the formation of a crosslinked structure due to hydrogen bond formation,
Thereby, crystallization due to self-crosslinking due to hydrogen bond formation of the hydrophilic polymer can be prevented.

Examples of the polyhydric alcohol (A) which can be used in the present invention include ethylene glycol, triethylene glycol, diethylene glycol, triethylene glycol,
Tetraethylene glycol, polyethylene glycol 20
0,300,400,600, propylene glycol, glycerin and the like. Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and triethylene glycol monomethyl ether.

Examples of the nitrogen-containing heterocyclic compound (B) which can be used in the present invention include ethylene urea derivatives such as 1,3, dimethylimidazolidinone and ethylene urea, and pyrrolidone derivatives such as 2-pyrrolidone and N-methyl-2-pyrrolidone. And the like.

Examples of the alkanolamines include triethanolamine, tripropanolamine, and N-butylethanolamine.

In the present invention, the total amount of (A) and (B) needs to be 5 to 40% by weight based on the recording agent.

If it is less than 5% by weight, moisture evaporation cannot be sufficiently suppressed, and if it exceeds 40% by weight, there is a problem that printing cannot be performed unless the recording voltage is increased due to a decrease in conductivity.
The ratio of the component (A) to the component (B) needs to be appropriately selected depending on the total amount and type thereof and the composition of the recording agent. For example, in the case of polyhydric alcohols and N-methyl-2-pyrrolidone, it is preferable to use them in the range of 4: 1 to 1: 8, and in the case of polyhydric alcohols and triethanolamine,
It is preferable to use in the range of 10: 1 to 3: 2.

In addition, the following various additives can be used as needed in the recording agent of the present invention.

As the pH adjuster, any substance can be used as long as the pH can be controlled without adversely affecting the prepared recording agent. Examples thereof include diethanolamine, amines such as triethanolamine, lithium hydroxide, sodium hydroxide, alkali metal hydroxides such as potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, and quaternary phosphonium hydroxide. Examples thereof include alkali metal carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate.

Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrate, pentaerythritol tetranitrate, dicyclohexylammonium nitrate and the like.

Examples of the coloring material used include pigments used in aqueous inks, colored fine particles, oil-soluble dyes, and dispersible dyes. Any coloring material that is insoluble in water, which is the main medium of the recording agent, can be used. Can also be used. In particular, pigments or colored fine particles having a particle size of 0.1 μm to 20 μm include those which are unlikely to cause image fogging. When the particle size is 0.1 μm or less, the holding power of the recording agent becomes insufficient, and when the particle size is 20 μm or more, there is a problem that the resolution of an image is deteriorated. Various surfactants can be added to obtain the dispersion stability of the coloring material.

In addition, an antiseptic and a fungicide can be added to the recording agent as required.

FIG. 1 shows an example of an apparatus for forming an image using the recording agent of the present invention. With reference to FIG. 1, a basic configuration of the image recording apparatus will be described.

The recording agent 3 is coated on the recording agent carrying roll 8 by a recording agent supply roll 11 from a recording agent container 12 having a heater (not shown). The conductive substrate constituting the recording agent carrying roll 8 is made of, for example, iron, nickel, or an aluminum substrate on which corrosion-resistant gold, platinum, or the like is deposited.

The layer thickness of the recording agent is kept constant by the recording agent layer thickness control means 5 and is transferred to the recording section. The recording electrode 2 applies a DC voltage between the recording electrode 2 and the electrode substrate so as to function as an anode. Thereby, the recording material 3 becomes fluid. 5 is a recording paper, and a paper feed roller
The sheet is conveyed to the transfer section by 6a and 6b, and is discharged from discharge rollers 6c and 6d. During this time, the recording paper is inserted into the minute gap between the backup roll 7 and the recording agent layer, and comes into contact with the recording agent layer. This contact causes the fluidized recording agent portion to adhere to and be absorbed by the recording paper, thereby forming an image. The unevenness of the transferred part and the part that was not transferred after the transfer,
The pH distribution formed by energization is smoothed and made uniform by a smoothing roll 9 having a heater (not shown). Thus, printing can be performed many times by supplying the recording material once. FIG. 2 is an enlarged view of a recording electrode, and 14 is a member for holding a conductive member 13, which is made of a material having a low energy surface such as polytetrafluoroethylene, or whose surface is made of perfluorooctanol polymethacrylic acid. It is preferable to use an insulating member processed with a water repellent such as an ester. 17 is a conductor, nickel, copper,
Metals such as stainless steel, gold and platinum, carbon, SnO _{2 and the} like can also be used.

 Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 Polyvinyl alcohol solution (A) Polyvinyl alcohol (degree of polymerization: 1400 to 1700) 5% by weight Pure water Remaining The above composition was heated at 60 ° C., stirred and dissolved, and allowed to cool.
The solution was filtered through a μm Teflon filter to prepare an aqueous polyvinyl alcohol solution (A).

Pigment dispersion liquid (B) Carbon black (average particle size: 0.5 μm) 10% by weight Ethylene glycol 20% by weight N-methyl-2-pyrrolidone 20% by weight Polyethylene glycol alkyl ether 0.1% by weight Boric acid 0.8% by weight Sodium hydroxide 0.8% by weight % Pure water remaining amount The above composition was dispersed in a ball mill for 20 hours, and coarse particles were removed by a centrifugal separator and filtered by a 10 μm Teflon filter.
A pigment dispersion (B) was prepared.

Next, an equivalent amount of the solution (B) was added while the solution (A) was heated at 60 ° C., and the mixture was allowed to cool to obtain a gel recording agent.

Example 2 Disperse Dye Dispersion (C) CI Desperse Yellow 76 10% by weight Diethylene glycol 20% by weight 1.3-Dimethylimidazolidinone 20% by weight Anionic surfactant ionet D-2 (manufactured by Sanyo Chemical) 4% by weight Borax 2 Weight% Pure water Remaining amount The dispersion having the above composition was ultrasonically dispersed and filtered through a 1 μm Teflon filter to obtain a dispersed dye dispersion (C).

Next, while heating and stirring the solution (A) of Example 1 at 60 ° C., an equivalent amount of the solution (C) was added and the mixture was allowed to cool to obtain a gel recording agent.

Example 3 Pigment Dispersion (D) Lake Pigment (Average Particle Size 0.5 μm) 10% by weight Glycerin 15% by weight Triethanolamine 10% by weight Diethylene glycol monobutyl ether 4% by weight Boric acid 0.8% by weight Pure water Remaining amount Ball mill with the above composition For 20 hours, remove coarse particles with a centrifuge, and filter with a 10 μm Teflon filter.
A pigment dispersion (D) was prepared.

Next, while heating and stirring the solution (A) of Example 1 at 60 ° C., an equivalent amount of the solution (D) was added and the mixture was allowed to cool to obtain a gel recording agent.

Example 4 Pigment dispersion liquid (E) Phthalocyanine pigment (average particle size: 0.5 μm) 10% by weight Polyethylene glycol 200 20% by weight N-methyl-2-pyrrolidone 20% by weight Diethylene glycol monobutyl ether 4% by weight Borax 2% by weight Water residue The above composition was dispersed in a ball mill for 20 hours, the coarse particles were removed with a centrifuge, and the mixture was filtered with a 10 μm Teflon filter.
A pigment dispersion (E) was prepared.

Next, while heating and stirring the solution (A) of Example 1 at 60 ° C., an equivalent amount of the solution (E) was added and the mixture was allowed to cool to obtain a gel recording agent.

Comparative Example 1 A fluid recording agent was obtained by using the pigment dispersion (F) having the following composition in place of the pigment dispersion (B) in Example 1.

Pigment dispersion liquid (F) Carbon black (average particle size: 0.5 μm) 10% by weight Ethylene glycol 80% by weight Polyethylene glycol alkyl ether 0.1% by weight Boric acid 0.8% by weight Sodium hydroxide 0.8% by weight Pure water Remaining amount Comparative Example 2 Example In Example 1, a non-fluid recording agent was obtained by using a pigment dispersion (G) having the following composition instead of the pigment dispersion (B).

Carbon black (average particle size: 0.5 μm) 10% by weight N-methyl-2-pyrrolidone 50% by weight Polyethylene glycol alkyl ether 0.1% by weight Boric acid 0.8% by weight Sodium hydroxide 0.8% by weight Pure water Remaining Comparative Example 3 In Example 2 A non-fluid recording agent was obtained by using a disperse dye dispersion (H) having the following composition instead of the disperse dye dispersion (C).

Disperse dye dispersion (H) CI desperse yellow 76 10% by weight Anionic surfactant Ionnet D-2 (manufactured by Sanyo Chemical) 4% by weight Borax 2% by weight Pure water Remaining Examples 1 to 4 and Comparative Example 1 The recording apparatus shown in FIG. 1 was filled with the recording materials of Nos. 1 to 3, and a voltage was applied between the electrodes at 50 V and 1 msec in accordance with the image signal, and recording was performed.

After filling, the sample was allowed to stand in a room at 25 ° C. and 50% RH and a room at 0 ° C. in a low temperature for 3 days.

 The results of the above printing are shown below.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a recording agent that reduces the change over time of the crosslinked structure and does not change the recording characteristics. Further, since a change with time due to moisture evaporation can be sufficiently suppressed, a change in recording characteristics due to moisture evaporation when the printing apparatus is not operating can be suppressed.

As a result, the recording member is not disposable at one time as in the thermal transfer recording method, and plain paper can be used as the recording paper without deteriorating the advantages of the conventional non-impact method. It is possible to provide a recording agent having an advantage that a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of an image forming apparatus using the recording agent of the present invention, and FIG. 2 is an enlarged view of the recording electrode.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09D 11/00-11/14

Claims (1)

(57) [Claims] 1. A recording agent whose cross-linking structure is destroyed by application of thermal energy and / or an electrochemical reaction and capable of controlling the adhesion characteristics to a transfer-receiving medium, wherein the cross-linking agent comprises a hydrophilic polymer. In the recording agent comprising a structural material, a coloring material, water and a wetting agent, as the wetting agent, a polyhydric alcohol,
At least one organic solvent selected from the group of polyhydric alcohol alkyl ethers, and at least one organic solvent selected from the group of nitrogen-containing heterocyclic compounds and alkanolamines, as a total amount of the recording agent. A recording agent containing 5 to 40% by weight.