JPH07109432A - Ink composition and equipment for ink jet recording by using the same - Google Patents

Abstract

PURPOSE:To obtain an ink composition which, after printing, is free from ink strike-through and increases in optical density by incorporating a specified substance into an ink composition which is used for hot-melt ink jet recording, consists of at least a vehicle and a pigment, and is solid at ordinary temperature. CONSTITUTION:A colorless filler (e.g. zinc oxide) preferably having a particle diameter of 0.1-10mum is incorporated into an ink composition which is solid at ordinary temperature, consists of at least a vehicle (e.g. a mixture of paraffin wax and an ethylene/vinyl acetate copolymer) and a pigment (e.g. carbon black), and is to be melted by heating from ordinary temperature to high temperature and delivered in a molten state through the head of ink jet recording equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition which is in a solid state at room temperature, in which ink is heated and melted for recording at a temperature higher than room temperature and an ink jet recording apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, as an ink jet recording system, for example, so-called electric field control system for ejecting ink by utilizing electrostatic attraction; so-called drop-on for ejecting ink by utilizing vibration pressure of a piezo element is used. Demand method (pressure pulse method); various methods such as so-called thermal ink jet method, in which ink is ejected by using pressure generated by forming and growing bubbles by high heat, have been proposed. Can be obtained.

In these ink jet recording systems, an aqueous ink using water as a main solvent and an oil ink using an organic solvent as a main solvent are generally used. Printed images using water-based inks are generally inferior in water resistance, whereas oil-based inks can provide printed images having excellent water resistance.

However, since these water-based and oil-based inks are liquids at room temperature, blurring is likely to occur when printed on recording paper, and sufficient printing density cannot be obtained. Furthermore, since they are liquids, they are liquids. However, it has a drawback that it is likely to cause the occurrence of such a precipitate, which causes a great decrease in the reliability of the inkjet recording system.

For the purpose of improving the drawbacks of these conventional solution-type inks, so-called hot-melt type oil-based inks for ink jet recording using solid inks at room temperature have been proposed. Specifically, US Patent No. 36
No. 5,393,32, an ink containing a dialkyl sebacate ester, US Pat. No. 4,390,369.
JP-A No. 58-108271 and JP-A No. 58-108271 disclose an ink containing a natural wax.
No. 973, an ink containing stearic acid, and in JP-A No. 61-83268, an ink or an acid having 20 to 24 carbon atoms is contained, and further, a ketone having a relatively high melting point is contained. The ink containing the ink described in JP-A-62-48774 includes an ink containing a thermosetting resin having a high hydroxyl value, a solid organic solvent having a melting point of more than 150 ° C., and a small amount of a dye substance. In Japanese Patent Laid-Open No.-112627, a coloring material, a first solvent which is solid at room temperature and liquefies when heated to a temperature higher than room temperature, and a second solvent which is liquid at room temperature and has high volatility to dissolve the first solvent. JP-A-62-295973 proposes an ink containing the solvent described above, and an ink containing a synthetic wax having a polar group and a dye soluble in the wax.

[0006]

However, since these hot-melt type oil-based inks for ink jet recording use components which are melted by heat, it is not known immediately after printing, but the back of the paper gradually increases with the passage of time. The so-called strike-through (print-through), which is the bleeding of the ink on the screen, occurred.

The present invention has been made in order to solve the above-mentioned problems, and is an ink composition in which there is little strike-through (print-through) of ink on a printed material after printing and the optical density is increased. And an inkjet recording apparatus using the same.

[0008]

In order to achieve this object, the ink composition of the present invention is heated to a temperature higher than room temperature and melted, and is ejected from the head of an ink jet recording apparatus in that state, at least as a vehicle. The ink composition is a solid state ink composed of a pigment at room temperature, and is characterized by further containing a colorless filler.

Further, the ink jet recording apparatus of the present invention is
It is characterized in that the ink composition is ejected downward from the head.

[0010]

According to the ink composition of the present invention having the above-mentioned constitution, after the ink is ejected from the head of the ink jet recording apparatus at a temperature higher than room temperature and fixed on the recording paper, the filler of the coloring material is a pigment. Controls penetration into paper. Due to this action, there is little ink strikethrough (print through) after printing, and the optical density also increases.

Further, according to the ink jet recording apparatus of the present invention, the ink composition is ejected downward from the head, so that the fixability of the filler on the recording paper is improved, whereby the coloring material is used. The penetration of a pigment into the paper is further suppressed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings.

The hot-melt ink, which is the ink composition of the present invention, is used in a hot-melt ink jet recording apparatus and constitutes the vehicle 34.
60 to 90% by weight of a wax having a melting point of 50 to 150 ° C., and 10 to 10% of a resin which also constitutes the vehicle 34.
30% by weight, 1 to 5% by weight of the pigment 32 as a coloring material, and 1 to 10% by weight of the colorless filler 30 are included.

The ejected heat-meltable ink droplets adhere to the recording paper 10 in a hemispherical raised state as shown in FIG. The filler 30 is fixed on the recording paper 10 by its own weight in a state where the inside of the ink droplet is settled. Pigment 32
The sedimentation is prevented by the filler 30 fixed on the recording paper 10 and the toner is fixed on the filler 30 in a layered manner, whereby the strike-through after printing is eliminated. The vehicle 34 passes through the space between the fillers 30 and soaks into the recording paper 10 to be fixed and solidified to increase the fixing strength of the heat-meltable ink on the recording paper 10.

The light beam 36 emitted from above the heat-meltable ink droplets adhering to the recording paper 10 is transferred to the vehicle 34.
Which has passed through the flow path and is fixed as a layer on the filler 30.
After reaching 2, the light ray 36 is reflected by the recording paper 10 with almost no absorption.
The optical density of the hot melt ink drops is increased.

The wax having a melting point of 50 to 150 ° C. used in the hot-melt ink of this embodiment constitutes the main component of the hot-melt ink and is stable to heat. For example,
Petroleum wax, preferably paraffin wax or microcrystalline wax, vegetable wax, candelilla wax, carnauba wax, rice wax, or jojoba solid wax, animal wax, preferably beeswax, lanolin or whale wax, Mineral wax, preferably montan wax, synthetic hydrocarbon, preferably Fischer-Tropsch wax or polyethylene wax, hydrogenated wax, preferably hydrogenated castor oil or hydrogenated castor oil derivative, modified wax, preferably montan wax derivative, paraffin Wax derivatives, microcrystalline wax derivatives or polyethylene wax derivatives, higher fatty acids,
Preferably behenic acid, stearic acid, palmitic acid, myristic acid or lauric acid, higher alcohols, preferably stearyl alcohol or behenyl alcohol, hydroxystearic acid, preferably 12-hydroxystearic acid or 12-hydroxystearic acid derivatives, , Ketone, preferably stearone or laurone, fatty acid amide, preferably lauric acid amide, stearic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, 12-hydroxystearic acid amide, special fatty acid amide or N-substituted fatty acid Amides, amines, preferably dodecylamine, tetradecylamine or octadecylamine, esters,
Desirably methyl stearate, octadecyl stearate, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, ethylene glycol fatty acid ester, or polyoxyethylene fatty acid ester, polymerization wax, preferably α-olefin maleic anhydride copolymer Any conventionally known wax such as wax can be used without particular limitation. These waxes can be used alone or in admixture of two or more, and are preferably contained in the above heat-meltable ink in the range of 60 to 90% by weight.

The resin used in this embodiment is the recording paper 10
It functions to impart adhesiveness to the ink, control the viscosity of the ink, hinder the crystallinity of the wax, further impart the transparency of the ink, and sterically hinder the pigment. Specifically, for example, any conventionally known resin such as polyester resin, amino resin, polyurethane resin, acrylic resin can be used without particular limitation. These resins can be used alone or as a mixture of two or more kinds, and it is desirable that the resin is contained in the above heat-meltable ink in the range of 10 to 30% by weight.

As the pigment 33, pigments commonly used in the technical field of printing can be used regardless of whether they are organic or inorganic.

Concretely, for example, carbon black, cadmium red, molybdenum red, chrome yellow,
Cadmium yellow, titanium yellow, chromium oxide, viridian, titanium cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, slene pigment Conventionally known pigments such as a perylene pigment, a perinone pigment, a thioindigo pigment, a quinophthalone pigment, and a metal complex pigment can be used without particular limitation.
These pigments can be used alone or in admixture of two or more, and are preferably contained in the above ink in the range of 1 to 5% by weight.

As the colorless filler 32, inorganic particles and organic particles can be used.

Specifically, for example, zinc oxide, titanium oxide,
Zirconia, glass beads and the like that do not melt up to 150 ° C or higher, preferably 200 ° C or higher are preferable. The particle size is preferably about 0.1 μm to 10 μm.

<Example 1> Vehicle 3 in Example 1
Normal temperature solid wax as 4 is paraffin wax (paraffin wax standard product 155, manufactured by Nippon Seiro Co., Ltd.),
The resin as the vehicle 34 is an ethylene vinyl acetate copolymer (Evaflex 450, manufactured by Mitsui Polychemicals), and the pigment 32 is carbon black (MA-100,
As the colorless filler 30, zinc oxide (manufactured by Kanto Chemical Co., Inc.) is used.

Ink formulation Paraffin wax standard product 155 65% by weight Evaflex 450 23% by weight MA-100 3% by weight Zinc oxide (particle size 10 μm or less) 9% by weight The above heat-meltable ink is good on the recording paper 10. It showed excellent fixability. Further, when a recording paper on which the above ink was printed was allowed to stand for 6 hours in an environment of 40 ° C., it was confirmed that there was no show-through on the printing paper.

<Embodiment 2> Vehicle 3 in Embodiment 2
The room temperature solid wax as 4 is a microcrystalline wax (Hi-Mic 2065, manufactured by Nippon Seiro Co., Ltd.), the resin as the vehicle 34 is a hydrogenated petroleum resin (Alcon P-90, manufactured by Arakawa Chemical Industry Co., Ltd.), and the pigment 32 is , Quinacridone pigment (HOSTAPERM PINK E02, manufactured by Hoechst),
The colorless filler 30 is glass beads (made by Iwaki glass).

Ink Formulation Hi-Mic 2065 60% by weight Alcon P-90 27% by weight HOSTAPERM PINK E02 3% by weight Glass beads (particle size 10 μm or less) 10% by weight The above heat-meltable ink is good on recording paper 10. It exhibited fixability. Further, when a recording paper on which the above ink was printed was allowed to stand in an environment of 50 ° C. for 6 hours, it was confirmed that there was no show-through on the printing paper.

As the method for producing the hot-melt ink of this embodiment, 70 to 350 of the above wax and resin are used.
It may be prepared by heating and melting at a temperature of about 100 ° C., preferably about 100 to 250 ° C., and appropriately mixing the pigment 32 and the filler 30. Further, if necessary, a solvent that softens them, a dispersant, or the like may be appropriately combined, and the compounding ratio of these may be appropriately adjusted to adjust the viscosity and melt viscosity at room temperature. When preparing the ink, it is preferable to improve the compatibility and dispersibility with the wax by kneading with a disperser such as a roll mill, a sand grinder, a ball mill and an attritor.

An embodiment of the ink jet recording apparatus of the present invention using the above-mentioned hot melt ink will be described below with reference to the drawings.

FIG. 2 is a perspective view of an ink jet recording apparatus showing an embodiment of the present invention. In the figure, recording paper 1
0 is wound around the platen 16 and fed to the feed roller 12,
It is pressed horizontally by 14. An inkjet head 26 is vertically mounted on a carriage 24 which is guided by the guide shafts 20 and 22 and is movable in a direction parallel to the platen shaft so that the protruding direction of the heat-meltable ink faces downward. The inkjet head 26 has a plurality of nozzles that can independently eject ink droplets vertically downward.

The ink jet head 26 is scanned in a direction indicated by an arrow 28 parallel to the platen axis, and in response to the operation, ink droplets are selectively ejected from the nozzles to form an ink image on the recording paper 10. The recording paper 10 is conveyed by the rotation of the platen 16 and the feed rollers 12 and 14 in the sub-scanning direction indicated by the arrow 18 orthogonal to the scanning direction,
Printing is performed on the recording paper surface.

At this time, in the present embodiment, the heat-meltable ink droplets discharged downward are the recording paper 1 as shown in FIG.
It adheres to the recording paper 10 on the recording paper 10 due to its own weight.
This makes it possible to more effectively prevent strikethrough of the pigment 32 after printing.

[0031]

As is clear from the above description, the ink composition of the present invention is ejected from an ink jet recording apparatus at a temperature higher than room temperature, and is properly fixed on plain paper and various printing papers, and a filler is used. By including it, the show-through of the ink after printing is small and the optical density is increased. Further, in the ink jet recording apparatus of the present invention, by making the jet ejection direction vertically downward, the filler of the above ink composition is well fixed on plain paper or the like to more effectively prevent the show-through of the ink after printing. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a form of recording dots on a recording paper of a heat-meltable ink according to the present invention.

FIG. 2 is a perspective view showing an inkjet recording apparatus embodying the present invention.

[Explanation of symbols]

 10, recording paper 26, inkjet head 30, filler 32, pigment

Claims (2)

[Claims] 1. An ink composition which is heated to a temperature higher than room temperature and melted, and is ejected from a head of an ink jet recording apparatus in that state and which is solid at room temperature and comprises at least a vehicle and a pigment. An ink composition comprising: 2. The ink jet recording apparatus using the ink composition according to claim 1, wherein the ink composition is ejected downward from the head. apparatus.