JPH06200204A - Hot-melt ink and ink jet recording apparatus using the same - Google Patents

Abstract

PURPOSE:To provide a normally solid jet recording ink which can melt at a relatively low temperature and can cure immediately when irradiated with ultraviolet rays by mixing a wax having a melting point of 40-70 deg.C with a resin having a melting point of 40-70 deg.C and an ultraviolet-curing resin. CONSTITUTION:The objective ink comprises a wax having a melting point of 40-70 deg.C, a resin having a melting point of 40-70 deg.C, a prepolymer, a monomer, a photopolymerization initiator, a dye and a pigment. This ink is normally solid because it contains the above-specified wax and wax. When the ultraviolet- curable resin is irradiated with ultraviolet rays from an ultraviolet lamp 21, the ink can fix immediately and satisfactorily on plain paper or printing paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt ink used in an ink jet recording apparatus and an ink jet recording apparatus using the same. More specifically, the present invention relates to a heat-meltable ink in which recording is performed by heating and melting the ink at a temperature higher than room temperature, and an inkjet 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 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 above solvent and an ink containing a synthetic wax having a polar group and a dye soluble in the wax. However, these hot-melt type inkjet recording oil-based inks have a high melting point, and it takes time to melt the ink, which adversely affects the start-up performance of the printer. JP-A-56-93776 discloses an ultraviolet curable resin type ink composition having good adhesion to a metal surface, JP-A-57-1
In 23272, there is proposed a printing ink composition which is excellent in ultraviolet ray fast curing property, emulsifying property, easy cleaning property, blanket swelling property and the like. These ink groups were liquid at room temperature.

Further, Japanese Patent Application Laid-Open No. 3-269069 proposes a hot-melt type recording material containing a metallic soap as a main component, which is in a liquid state at 45 ° C. and changes into a solid state at room temperature.

[0007]

However, the above-mentioned hot melt type oil-based ink for ink jet recording has a high melting point, and it takes time to melt the ink, which adversely affects the start-up performance of the printer.

In the ink disclosed in Japanese Patent Laid-Open No. 3-269069, it took a long time for the ink to cure after fixing.

The present invention has been made in order to solve the above-mentioned problems, and can shorten the start-up time of the printer and can rapidly cure the ink after fixing the heat-melting ink and the ink jet recording apparatus. The purpose is to provide.

[0010]

In order to achieve this object, the hot-melt ink of the present invention contains a wax and a resin having a melting point of 40 to 70 ° C. and an ultraviolet curable resin. Further, the ink jet recording apparatus of the present invention has an ultraviolet irradiation device for curing the above-mentioned hot melt ink.

[0011]

The heat-fusible ink of the present invention having the above-mentioned constitution melts at a temperature of 40 to 70 ° C., adheres to plain paper and various printing papers, is then cured by ultraviolet rays, and is properly fixed on the paper. Further, the ink jet recording paper can rapidly cure and fix the ink adhered on various printing papers by an ultraviolet irradiation device.

[0012]

EXAMPLES The hot-melt ink of the present invention has a melting point of 4
70 to 90% by weight of wax and resin at 0 to 70 ° C., 10 to 30% by weight of prepolymer and monomer, 0.1 to 3% of photopolymerization initiator, and 1 to 5% by weight of dye and pigment. It is contained as an ingredient.

The melting point used in the ink of this embodiment is from 40 to 40.
Examples of the wax and resin at 70 ° C. are paraffin wax, polyvinyl ether, stearyl alcohol, sorbitan monostearate, polyethylene oxide, candelilla wax, wood wax, beeswax, lanolin, spermaceti wax, paraffin wax derivative, microcrystalline wax derivative, Ceresin, stearic acid, palmitic acid, myristic acid, lauric acid, α-olefin maleic anhydride copolymer wax, coconut oil, palm kernel oil, herring oil / cod liver oil, whale oil, palm oil, cottonseed oil, olive oil /
Peanut oil, soybean oil, linseed oil and the like can be mentioned.
Specifically, regarding paraffin wax, paraffin wax standard product No. 115 (melting point 47, manufactured by Nippon Seiro Co., Ltd.)
C), paraffin wax special product SP-0110 (melting point 44 ° C.) polyvinyl ether, Hoechst wax v (melting point 48.8 ° C.) manufactured by Hoechst Co., Ltd .;
0 (melting point 58.9 ° C.), and sorbitan monostearate, Leodol SPS10 (melting point 5 manufactured by Kao Corporation)
Examples of the polyethylene oxide include PO wax (melting point: 68.0 ° C.) manufactured by Nippon Oil Co., Ltd. The above organic substances may be used alone, or
You may mix 1 or more types.

As the prepolymer, any of prepolymers such as polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligo acrylate, alkyd acrylate and polyol acrylate can be used without particular limitation.

Examples of the monomer include diethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, hydroxypiperic acid ester neopentyl glycol diacrylate, trimethylolpropane triacrylate,
Any of these monomers can be used without particular limitation. The above prepolymers and monomers may be used alone or in combination of two or more.

As the photopolymerization initiator, isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether, benzoin methyl ether, 1-
Phenyl-1,2-propadion-2-oxime, 2,
2-dimethoxy-2-phenylacetophenone, benzyl, hydroxycyclohexyl phenyl ketone, diethoxyacetophenone, 2-hydroxy-2-methyl-1
To specifically limit any of the photopolymerization initiators such as phenylpropan-1-one, benzophenone, chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methylthioxanthone, chlorine-substituted benzophenone, and halogen-substituted alkyl-allyl ketone. Can be used without.

As the dye and pigment, those generally used in the technical field of printing can be used.

Specifically, for example, carbon black, iron oxide, nigrosine dye, lamp black, Sudan black SM, alkali blue, first yellow G, benzine yellow, pigment yellow, indo first orange, irgadine red, para Nitroaniline Red, Toluidine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Resole Red 20, Lake Red C, Rhodamine FB,
Rhodamine B Lake, Methyl Violet B Lake,
Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zabong Farst Yellow CGG, Kayaset Y963, Kayaset YG, Sumiblast Yellow GG, Savone First Orange RR, Oleil Scarlet, Sumiblast Orange G, Orazol Brown B, Pomelo First Scarlet CG, Eisenspiron Red BEH, Oil Pink OP, Victoria Blue F4R, Fastgen Blue 5007, Sudan Blue, Oil Beecock Blue, etc. It can be used without limitation. These dyes and pigments can be used alone or in admixture of two or more.
It is desirable that the content is 5% by weight.

Experimental Examples Paraffin Wax Paraffin Wax Paraffin Wax Standard No. 115 manufactured by Nippon Seiro Co., Ltd. 80% by weight Polyester acrylate 18% by weight Isobutyl benzoin ether 1% by weight Carbon black (Mitsubishi Kasei) 1% by weight The ink had a melting point of 49 ° C. And it showed good fixing property on the recording paper.

As a method for producing the ink of this embodiment, the wax and resin as described above are heated and melted at a temperature of about 40 to 250 ° C., preferably about 50 to 150 ° C., and a prepolymer, a monomer, and a light are used. It may be prepared by appropriately mixing the polymerization initiator and the dye or pigment or a mixture thereof. 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 in which the hot-melt ink and the ink jet recording apparatus of this embodiment are embodied will be described below with reference to the drawings.

FIG. 1 is a perspective view of an ink jet recording apparatus showing an embodiment of the present invention. In the figure, recording paper 10
Is wound around the platen 16 and the feed rollers 12, 1
Pressed by 4. A carriage 2 that is guided by the guide shafts 20 and 22 and is movable in a direction parallel to the platen shaft.
4, an ink jet head 26 is mounted on the head 4. The inkjet head 26 has a plurality of nozzles capable of ejecting ink droplets independently and is scanned in a direction indicated by an arrow 28 parallel to the platen axis, and in accordance with the operation, ink droplets are selectively ejected from the nozzles. An ink image is formed 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 shown by the arrow 18 orthogonal to the scanning direction, and printing is performed on the recording paper surface. The ultraviolet irradiation lamp 21 is installed downstream in the sub-scanning direction, and irradiates the ink on the recording paper surface being conveyed with ultraviolet light.

FIG. 2 shows a cross section of the ink jet head. A frame 36 made of aluminum has a unimorph structure vibrator 30 made of a piezoelectric material and a thin metal layer. Further, a nozzle forming member 34 made of a nickel plate having a thickness of 100 μm is laminated and fixed between the two via a spacer 32 also made of a nickel plate. The vibrator is arranged so that the nozzle forming member and the thin metal layer face each other.
The nozzle forming member 34 has a plurality of nozzles 38 each having a minute opening with a diameter of 50 μm. A heater 40 for heating ink is provided on the bottom surface of the frame. As described above, the ink 42 is mainly composed of wax or the like, and has a dye or pigment dissolved therein. In this embodiment, the ink 42 in the head is heated by the heater 40 in order to keep the temperature at 40 to 70 ° C., which has an appropriate viscosity. The heater 40 is fed back by a temperature sensor (not shown) to keep the ink at a constant temperature.

Next, the operation will be described. The ink is supplied to the head in a solid state. The ink is heated to a predetermined temperature above the melting point by the heater 40 and liquefied, and the vibrator 30
Is supplied by the capillary force to the periphery of the
It enters into and is held in the gap between the vibrator 30 and the nozzle forming member 34, which are kept in a minute dimension of μm. At the time of ejection, a voltage is applied to the piezoelectric material of a desired vibrator among the plurality of vibrators 30 described above to cause the unimorph vibrator to warp. Length 2
The tip of the mm-shaped cantilever oscillator is displaced by 15 μm when a voltage of 150 V is applied. Next, when this voltage is released, the vibrator is displaced toward the nozzle forming member by the elastic restoring force, and is generated in the liquid ink 42 interposed between the tip free end portion of the vibrator 30 and the nozzle forming member 34. The ink is ejected from the nozzle 38 with the pressure applied.

The ejected ink droplets adhere to the recording paper 10 in a substantially hemispherical raised state as shown in FIG.
After that, by absorbing the ultraviolet rays of the ultraviolet irradiation lamp 21 provided in the ink jet recording apparatus, it is quickly cured and fixed. At this time, a part of the ink penetrates into the recording paper 10 at the portion contacting the recording paper 10, but the recording dots 4
The shape of 6 is kept almost hemispherical.

Although the ink droplets ejected by the ultraviolet irradiation lamp are cured and fixed in the above-mentioned embodiment, they may be cured by absorbing ultraviolet rays in the natural world.

[0027]

As is apparent from the above description, the ink of the present invention not only allows easy formation of a clear image on plain paper and various printing papers, but also is an ink composition component. If the ultraviolet ray curing resin is provided with an ultraviolet ray irradiating device in the ink jet recording apparatus after recording, it can be immediately cured by irradiating it with ultraviolet rays.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus that embodies an inkjet head according to an embodiment of the present invention.

FIG. 2 is a sectional view of the inkjet head.

FIG. 3 is a diagram showing a recording dot form on a recording paper of a heat-meltable ink according to the present invention.

[Explanation of symbols]

 10 recording paper 26 inkjet head 42 ink 46 recording dot

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area C09D 11/10 PTR 7415-4J

Claims (2)

[Claims] 1. A heat-meltable ink comprising a wax and a resin which are solid or semi-solid at room temperature and have a melting point at a temperature of 40 to 70 ° C., and an ultraviolet curable resin which is cured by irradiation with ultraviolet rays. 2. An ink jet recording apparatus comprising an ultraviolet irradiation device for curing the hot melt ink according to claim 1.