JP6728823B2 - Image forming method and image forming apparatus - Google Patents

Description

The present invention relates to an image forming how relates images forming device.

The inkjet recording method has advantages that the process is simpler, full-colorization is easier than other recording methods, and an image with high resolution can be obtained even with an apparatus having a simple structure. As a result, it has become widespread and is spreading from personal to office applications, commercial printing and industrial printing.

In the field of commercial printing and industrial printing, coated paper such as coated paper and art paper is used as a recording medium in addition to plain paper.Coated paper has high image gloss in addition to high image density. A high degree of fixability is required.

With the expansion of the inkjet recording system into the fields of commercial printing and industrial printing, productivity is required, and the printing speed is increasing year by year. In addition, water-based inks are often used because of their safety, ease of handling, and environmental considerations.

In general, when using a water-based ink to print at high speed by an inkjet method, the organic solvent containing water in the ink has a slow penetration speed into the paper, so the organic solvent containing water remains on the surface of the recording medium, The image was lost due to transfer or rubbing, and there was a problem in fixability. Further, in the case of paper having a small basis weight, there is a problem of paper deformation due to the difference in paper expansion/contraction ratio between the printing portion and the non-printing portion.

As an example of a method for solving such a problem, a resin-coated pigment in which at least a part of pigment particles are coated with a water-insoluble resin, resin particles, wax particles, 1,2-alkylenediol, polyhydric alcohol, and pyrrolidone derivative An ink applying step of applying an ink composition containing an acetylene glycol-based surfactant from an ejection head to a recording medium at a moving speed between the ejection head and the recording medium in the sub-scanning direction of 200 mm/sec or more; The drying step of drying the recording medium to which the ink has been applied and the recording medium after drying are integrated by providing a step of adhering a powdery substance having an average particle diameter of 1 to 100 μm to 1 to 1000 mg/m ² on the recording medium. An image forming method including a stacking step is disclosed (for example, refer to Patent Document 1).

However, the disclosed image forming method focuses only on scratch resistance (fixability), and there is room for improvement in blocking resistance.

An object of the present invention is to provide an image forming method having excellent fixability and blocking resistance.

The image forming method includes a step of applying a first liquid used for image formation to an ejection target by a liquid ejection head, and a surface of the ejection target on a side to which the first liquid is applied, The step of spraying a second liquid containing at least one of a water-soluble wax and a water-dispersible wax with air at 60 ° C. or higher and 140 ° C. or lower by a spraying device, and after the step of spraying by the spraying device, the discharge target object And the step of heating .

The disclosed technique can provide an image forming method having excellent fixing properties and blocking resistance.

FIG. 3 is a schematic diagram illustrating an image forming apparatus and an image forming method according to the present embodiment. It is a schematic diagram explaining the spraying apparatus which concerns on this Embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be denoted by the same reference numerals and redundant description may be omitted.

The image forming method according to the present embodiment includes a step of applying a first liquid used for image formation to an ejection target by a liquid ejection head, and a step of applying the first liquid of the ejection target on the side. Spraying the second liquid containing a non-volatile component on the surface with a gas of 50° C. or higher and 350° C. or lower by a spraying device.

Here, the first liquid used for image formation is, for example, an ink containing a coloring material and water. The second liquid is a coating liquid sprayed by a spray device. The ejection target is a recording medium such as coated paper.

Hereinafter, the first liquid will be described as an ink containing a coloring material and water, the second liquid as a coating liquid, and the ejection target as a recording medium such as coated paper. The first liquid is used for image formation. It may be a liquid and is not limited to an ink containing a coloring material and water. The ejection target is not limited to a recording medium such as coated paper as long as it is a target on which an image is formed.

The non-volatile component is applied to the surface of the recording medium on which the ink is applied together with a gas of 50° C. or higher and 350° C. or lower by a spraying device, so that the non-volatile component is adhered to the recording medium. Drying of the sprayed droplets of the coating liquid containing is progressed, and the non-volatile components are uniformly arranged on the surface layer of the surface of the recording medium on which the ink is applied.

In addition, the gas (warm air) of 50° C. or higher and 350° C. or lower ejected from the spraying device promotes the drying of the ink near the surface layer of the surface of the recording medium on which the ink is applied, and the non-volatile component causes the inside of the ink layer to disappear. Prevent entry.

An image formed by the ink can be protected by the non-volatile component uniformly arranged on the surface layer without entering the inside of the ink layer.

Furthermore, the coating liquid containing the non-volatile component also thinly and uniformly wets the non-printed portion, thereby reducing the difference in expansion and contraction between the printed portion and the non-printed portion. As a result, it is possible to form an image on the coated paper which is excellent in image density, image glossiness, fixability and blocking resistance, and which causes little paper deformation.

As described above, in the image forming method according to the present embodiment, it is possible to realize the image forming method capable of improving the protection performance (for example, fixing property, blocking resistance, etc.) with respect to the ink applied to the recording medium.

Hereinafter, the image forming method according to this embodiment will be described in detail.

<Nonvolatile component>
The non-volatile components include powdery substances and wax.

<Powder>
In the present embodiment, the powdery material means a powdery solid or a granular solid having an average particle diameter of about 0.01 μm to 1000 μm.

The material forming the powdery material is not particularly limited, but any of inorganic materials such as metals, metal oxides, ceramics and silica, and organic materials such as resins, cellulose and rubber can be used.

The powdery substance is not particularly limited, but it is preferable that it is dispersed in water without precipitation. As a method of dispersing the powdery substance in water, a method of binding an atomic group or resin containing at least one anionic hydrophilic group/nonionic hydrophilic group/cationic hydrophilic group to the surface of the powdery substance, at least one type A method of coating with a resin containing an anionic hydrophilic group/nonionic hydrophilic group/cationic hydrophilic group, and a method of dispersing with a dispersant containing at least one anionic hydrophilic group/nonionic hydrophilic group/cationic hydrophilic group. Can be mentioned.

It is preferable to use a resin as the powder, and by using the resin as the powder, it is possible to further improve the image density, the image glossiness, the fixing property and the blocking resistance of the image formed on the coated paper. You can

Note that the water-dispersible wax described later can be regarded as included in the powdery substance, but in the present embodiment, the water-dispersible wax is included in the wax, not the powdery substance, for convenience. Treat as a thing.

<Wax>
The wax is not particularly limited, but a wax exhibiting water solubility (hereinafter referred to as water soluble wax) or a wax exhibiting water dispersibility (hereinafter referred to as water dispersible wax) can be used.

As the water-soluble wax, a wax having a hydrophilic group such as a hydroxyl group, a carboxyl group, an ethylene oxide group and an amino group can be used. The water-dispersible wax can be used mainly as a wax emulsion.

Specific examples of the water-soluble wax or water-dispersible wax include plants such as carnauba wax, candelilla wax, beeswax, rice wax, and lanolin, animal wax, paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, oxidation. Polyethylene wax, petroleum wax such as petrolatum, montan wax, mineral wax such as ozokerite, carbon wax, Hoechst wax, polyethylene wax, synthetic waxes such as stearic acid amide, α-olefin/maleic anhydride copolymer, etc. The natural and synthetic wax emulsions and compounded waxes can be used alone or in combination of two or more. Further, as the water-soluble wax or the water-dispersible wax, latex, colloidal solution, suspension or the like can be used.

It is also possible to use a commercially available wax, and specific examples thereof include Cerosol 524 (carnauba wax having a melting point of 83° C. and a particle diameter of 200 nm) (manufactured by Chukyo Yushi Co., Ltd.), HYTEC E-6500 ( Polyethylene wax having a melting point of 140° C. and a particle size of 60 nm (manufactured by Toho Chemical Co., Ltd.), HYTEC E-8237 (polyethylene wax having a melting point of 106° C., a particle size of 80 nm) (manufactured by Toho Chemical Co., Ltd.), HYTEC P-9018 (manufactured by Toho Chemical Co., Ltd.). Polypropylene wax having a melting point of 156° C. and a particle size of 60 nm (manufactured by Toho Kagaku), Nopcoat PEM-177 (polyolefin wax having a melting point of 105° C. and a particle size of 10 nm) (manufactured by San Nopco), AQUACER® 498 (Paraffin wax having a melting point of 58° C.) (manufactured by BYK Chemie Japan), AQUACER (registered trademark) 535 (mixed wax having a melting point of 95° C.) (manufactured by BYK Chemie Japan), AQUACER (registered trademark) 531 (melting point) Of 130° C. and a particle size of 123 nm (made by Big Chemie Japan), AQUACER® 515 (polyethylene wax having a melting point of 135° C. and a particle size of 33 nm) (made by Big Chemie Japan), etc. To be

<Color material>
The colorant is not particularly limited, but pigments and dyes can be used. Among these, pigments are preferable from the viewpoints of image density and glossiness of images formed on coated paper.

The pigment is not particularly limited, but a pigment having at least one kind of anionic hydrophilic group on the surface and exhibiting water dispersibility or water solubility is preferable. As the pigment exhibiting water dispersibility or water solubility, a pigment (1) dispersed with a dispersant having at least one kind of anionic hydrophilic group, a pigment coated with a resin having at least one kind of anionic hydrophilic group ( 2), a pigment (3) to which a resin having at least one anionic hydrophilic group, an atomic group containing at least one anionic hydrophilic group, or at least one anionic hydrophilic group is bound.

The pigment (1) is generally called a surfactant-dispersed pigment or a resin-dispersed pigment, and the dispersant takes an interface between the pigment and water to disperse the pigment in water.

The pigment (2) is generally called a capsule pigment, which has an anionic hydrophilic group, is coated with a water-insoluble resin, and is made hydrophilic so that the pigment is dispersed in water. Is.

The pigment (3) is generally called a self-dispersion pigment, and is a material in which carbon black or the like is mainly surface-oxidized to be hydrophilic so that the pigment is dispersed in water.

The pigment is not particularly limited and may be appropriately selected depending on the purpose, and may be, for example, an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more.

Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, dark blue, cadmium red, chrome yellow, metal powder, carbon black and the like. Among these, carbon black is preferable. Examples of carbon black include those manufactured by known methods such as a contact method, a furnace method, and a thermal method.

Examples of organic pigments include azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are preferable.

Examples of the azo pigment include azo lake, insoluble azo pigment, condensed azo pigment, chelate azo pigment, and the like. Examples of the polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofuraron pigments, and rhodamine B lake pigments. Examples of dye chelates include basic dye chelates and acid dye chelates.

Examples of black pigments include carbon black (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, copper, iron (CI Pigment Black 11), titanium oxide. And the like, organic pigments such as aniline black (CI Pigment Black 1), and the like.

The carbon black, a furnace method, a carbon black produced by the channel method, primary particle diameter of 15Nm～40nm, BET specific surface area is ^{50m 2 / g~300m 2 / g,} DBP oil absorption amount 40 ml / 100 g to Those having 150 ml/100 g, a volatile content of 0.5% to 10% and a pH value of 2 to 9 are preferable.

A commercial item can be used as carbon black. Examples of commercially available products include No. 2300, No. 900, MCF-88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 52. 2200B (all manufactured by Mitsubishi Chemical Co.); Raven700, 5750, 5250, 5000, 3500, 1255 (all manufactured by Columbia); Regal400R, 330R, 660R, Mogul L, Monarch (registered) Trademarks) 700, 800, 880, 900, 1000, 1100, 1300, Monarch (registered trademark) 1400 (all manufactured by Cabot Corporation); color black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, 4 (all manufactured by Degussa) Can be mentioned.

The color pigment that can be used in the yellow ink is not particularly limited and may be appropriately selected depending on the intended purpose. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 120, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 174, C.I. I. Pigment Yellow 180 and the like.

The color pigment that can be used in the magenta ink is not particularly limited and may be appropriately selected depending on the intended purpose. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 57:1, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 146, C.I. I. Pigment Red 168, C.I. I. Pigment Red 176, C.I. I. Pigment Red 184, C.I. I. Pigment Red 185, C.I. I. Pigment Red 202, Pigment Violet 19, and the like.

There is no particular limitation on the pigment that can be used in the cyan ink for color and may be appropriately selected according to the purpose. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15:3, C.I. I. Pigment Blue 15:4, C.I. I. Pigment Blue 15:34, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60, C.I. I. Pigment Blue 63, C.I. I. Pigment Blue 66; C.I. I. Bat Blue 4, C.I. I. Bat blue 60 and the like can be mentioned.

By using Pigment Yellow 74 as the yellow pigment, Pigment Red 122 and Pigment Violet 19 as the magenta pigment, and Pigment Blue 15:3 as the cyan pigment, a well-balanced ink having excellent color tone and light resistance is obtained. be able to.

<water>
Examples of water include deionized water, ultrafiltered water, reverse osmosis water, pure water such as distilled water, high pure water, and ultrapure water. The content of water in the ink is preferably 20 to 60% by mass.

<Ink>
In addition to the coloring material and water, the ink may include an organic solvent, a surfactant, a resin, a pH adjusting agent, an antiseptic/antifungal agent, an anticorrosive agent, an antioxidant, an ultraviolet absorber, an oxygen absorber, if necessary. It may further contain a light stabilizer and the like.

When manufacturing an ink, it is preferable to filter coarse particles using a filter, a centrifuge, or the like, after mixing the components, and to deaerate. When the ink is applied to the recording medium by the liquid discharge head (applied by the inkjet method), an image forming apparatus described later can be used.

<Coating liquid>
The coating liquid contains a non-volatile component. As the coating liquid, an aqueous dispersion of powder or a wax emulsion can be used. The coating liquid preferably contains wax. When the coating liquid contains wax, the image density, image glossiness, fixability and blocking resistance of the image formed on the coated paper can be further improved.

The resin emulsion is not particularly limited, but an acrylic resin emulsion, a polyurethane emulsion, a styrene-acrylic resin emulsion, an acrylic-silicone resin emulsion, or a fluororesin emulsion can be used.

Commercially available polyurethane emulsions include SF460, SF460S, SF420, SF110, SF300, SF361 (manufactured by Unicar Japan), Bondic series (manufactured by DIC), Takelac W, WS series, W5025, W5661 (manufactured by Mitsui Chemicals). Etc.

As commercial products of styrene-acrylic resin emulsion, J-450, J-734, J-7600, J-352, J-390, J-7100, J-741, J74J, J-511, J-840, J-775, HRC-1645, HPD-71 (above, Johnson Polymer make) etc. are mentioned.

Examples of commercially available acrylic-silicone resin emulsions include UVA383MA (manufactured by BASF) and AP4710 (manufactured by Showa High Polymer Co., Ltd.).

Examples of commercially available fluororesin emulsions include FE4300, FE4500 and FE4400 (all manufactured by Asahi Glass Co., Ltd.).

As the coating liquid, a wax emulsion and a resin emulsion may be mixed and used.

If necessary, the coating liquid further contains an organic solvent, a surfactant, a pH adjuster, an antiseptic/antifungal agent, a rust preventive, an antioxidant, an ultraviolet absorber, an oxygen absorber, a light stabilizer and the like. But it's okay.

When applying the coating liquid to the recording medium, a spraying device described later can be used.

<Image forming apparatus and image forming method>
The image forming apparatus according to the present embodiment records a liquid ejection head that applies an ink containing a coloring material and water to a recording medium, and a coating liquid containing a non-volatile component together with a gas of 50° C. or higher and 350° C. or lower for recording. And a spraying device for applying to the surface of the medium on which the ink is applied. The image forming apparatus according to the present exemplary embodiment may further include appropriately selected other units such as a conveyance unit, a drying unit, and a control unit, if necessary.

FIG. 1 is a schematic diagram illustrating an image forming apparatus and an image forming method according to this embodiment. The image recording apparatus 1 illustrated in FIG. 1 is an inkjet recording apparatus, and includes a liquid ejection head 10 and a spraying device 20 as main components.

In the image forming apparatus 1, the liquid ejection head 10, the warm air device 120 and the heating roller 130, the spray device 20, the liquid supply device 30, and the warm air device 140 from the upstream side in the direction (arrow direction) in which the recording medium 300 is conveyed. Also, a heating roller 150 is arranged.

To form an image using the image forming apparatus 1, first, an ink containing a color material and water is recorded on a recording medium 300 such as coated paper that is unwound from the unwinding roller 110 and is conveyed in the arrow direction. Is applied (discharged) by the liquid discharge head 10 to form an image. Details of the liquid ejection head 10 will be described later.

Next, the formed image is dried by the contact between the warm air sent from the warm air device 120 and the heating roller 130. After that, a coating liquid containing a non-volatile component is sprayed together with a gas (warm air) having a predetermined temperature or higher by the spraying device 20, and is applied to the surface of the recording medium 300 on the ink coated side. The coating liquid is supplied from the liquid supply device 30 to the spray device 20. Details of the spray device 20 and the liquid supply device 30 will be described later.

After that, the image is dried again by the warm air sent from the warm air device 140 and the heating roller 150 (fixing step), the recording medium 300 is wound up by the winding roller 160, and the image formation is completed. The warm air devices 120 and 140 and the heating rollers 130 and 150 are not essential components.

In the example of FIG. 1, a step of spraying a coating liquid containing a non-volatile component together with a gas (warm air) having a predetermined temperature or higher by the spraying device 20 and coating the surface of the recording medium 300 on the ink coated side A heating process for heating the recording medium 300 is provided both before and after. However, the heating step may be provided only before or after the step of applying with the spray device 20.

By providing a heating step before or after the step of applying with the spraying device 20 or both, it is possible to further improve the fixability and blocking resistance of the image formed on the recording medium 300 such as coated paper. .. In particular, it is preferable to provide a heating step after the step of applying with the spraying device 20 because the fixing property and blocking resistance of the image can be further improved.

[Liquid ejection head]
The liquid ejection head 10 is a unit that applies a stimulus to ink to eject the ink. The stimulus is not particularly limited and may be appropriately selected depending on the intended purpose, and examples thereof include heat (temperature), pressure, vibration and light. These may be used alone or in combination of two or more. Among these, heat and pressure are preferable.

Specific examples include a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change due to film boiling of a liquid using an electrothermal conversion element such as a heating resistor, a shape memory alloy actuator that uses a metal phase change due to a temperature change, An electrostatic actuator or the like that uses electrostatic force can be used.

The mode of flight of the ink is not particularly limited and varies depending on the type of stimulus and the like. For example, as a mode of flight of the ink when the stimulus is heat, thermal energy corresponding to a recording signal is applied to the ink in the liquid ejection head 10 by using, for example, a thermal head, and There is a method in which bubbles are generated in the ink and the pressure of the bubbles causes the ink to be ejected and ejected as droplets from the nozzle holes of the liquid ejection head 10.

When the stimulus is pressure, as a mode of ink flight, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the liquid ejection head 10, Examples include a method of bending the piezoelectric element to reduce the volume of the pressure chamber and ejecting and ejecting ink as droplets from the nozzle holes of the liquid ejection head 10.

In the example of FIG. 1, the liquid ejection head 10 is a full line type head, and black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the transport direction of the recording medium 300. 4 heads K, C, M, and Y that are compatible with the above are arranged.

[Spraying device]
FIG. 2 is a schematic diagram illustrating the spraying device according to the present embodiment. As shown in FIG. 2, the spraying device 20 has a sprayer 21 and a warm air generator 22.

The sprayer 21 includes a liquid introduction passage 211 into which a coating liquid is introduced from a liquid supply device 30 provided outside the spraying device 20, and a gas introduction into which a gas (warm air) having a predetermined temperature is introduced from a warm air generator 22. A passage 212 and a nozzle 213 for mixing and spraying the coating liquid introduced into the liquid introduction passage 211 and the gas introduced into the gas introduction passage 212 are provided.

The warm air generator 22 is a device that generates a gas (warm air) having a predetermined temperature and introduces the generated gas into the gas introduction path 212. The gas introduced into the gas introduction path 212 can be, for example, air or nitrogen. The temperature of the gas introduced into the gas introduction path 212 is preferably 50° C. or higher and 350° C. or lower.

The temperature detecting means 23 may be provided outside the end of the gas introduction path 212 on the nozzle 213 side. In this case, the temperature detection means 23 detects the temperature of the gas introduced into the gas introduction path 212 immediately before being introduced into the nozzle 213, and outputs the detection result to the hot air generator 22. As the temperature detecting means 23, for example, a thermocouple can be used.

The hot air generator 22 controls the temperature of the gas introduced into the gas introduction path 212 based on the detection result of the temperature detection means 23. For example, the temperature of the gas introduced into the gas introduction path 212 is controlled so that the temperature of the gas detected by the temperature detection means 23 becomes 50° C. or higher and 350° C. or lower.

The temperature detected by the temperature detecting means 23 and the actual (ambient) temperature of the gas may differ depending on the system configuration. If there is an equilibrium state in the vicinity of the temperature detecting means 23 connected to the gas introduction path 212, the temperature detected by the temperature detecting means 23 will be the ambient temperature of the gas. However, depending on the installation location of the temperature detecting means 23 and the like, there may be a case where a temperature difference occurs between the temperature detected by the temperature detecting means 23 and the actual ambient temperature of the gas. In this case, needless to say, the temperature control is performed by the warm air generator 22 in consideration of the temperature difference.

When the temperature detecting means 23 is not provided, the temperature difference between the temperature of the gas generated by the hot air generator 22 and the temperature of the gas near the end of the gas introduction path 212 on the nozzle 213 side is obtained in advance, and the temperature The wind generator 22 may generate a gas having a temperature in consideration of the temperature difference. For example, when the temperature difference obtained in advance is 5° C. and the temperature of the gas in the vicinity of the end of the gas introduction path 212 on the nozzle 213 side is desired to be 50° C., the warm air generator 22 generates the gas at 55° C. It may be introduced into the gas introduction path 212.

The liquid supply device 30 introduces the coating liquid containing a volatile component into the liquid introduction passage 211 in a predetermined liquid feed amount. As a method of introducing (delivering) the coating liquid into the liquid introducing passage 211 by the liquid supply device 30, for example, a pressure method of feeding by a pump or a pressure tank, or a siphon method of feeding by utilizing a gas suction effect. Etc.

In addition, in the example of FIG. 2, the liquid supply device 30 is provided as a separate body from the spray device 20, but the liquid supply device 30 may be incorporated in the spray device 20. In this case, the spraying device 20 has a structure including a sprayer 21, a warm air generator 22, and a liquid supply device 30.

The material for the liquid introduction passage 211, the gas introduction passage 212, and the nozzle 213 is not particularly limited, but SUS304, SUS316, brass, iron, aluminum, polypropylene, ABS resin, fluororesin, hard polyvinyl chloride, or the like is used. You can

In FIG. 2, 300 is a recording medium, and 310 is the ink applied to the recording medium 300 by the liquid ejection head. The recording medium 300 is, for example, roll paper and can be conveyed in the arrow direction.

The spraying device 20 mixes the coating liquid containing the non-volatile component introduced into the liquid introduction passage 211 and the gas at the predetermined temperature introduced into the gas introduction passage 212 in the nozzle 213 and directs it from the nozzle 213 toward the ink 310. To spray. The distance between the tip of the nozzle 213 and the recording medium 300 is not particularly limited, but may be, for example, several tens of cm.

For example, a gas having a predetermined temperature is always introduced from the warm air generator 22 to the gas introduction path 212, and the coating liquid is introduced from the liquid supply device 30 at a predetermined timing, so that the nozzle 213 sprays at a desired timing. be able to. The spray pattern of the nozzle 213 is not particularly limited, but may be a flat pattern, a full cone pattern, a hollow cone pattern, a straight pattern, or the like.

(Example)
In this example, “part” means “part by mass”.

[Pigment Dispersion PD-1 (Black)]
160 parts of carbon black NIPEX160 (manufactured by Degussa) having a BET specific surface area of 150 m ² /g, an average primary particle size of 20 nm, a pH of 4.0, and a DBP oil absorption of 620 g/100 g, polyoxyethylene (POE) (m= 40)-β-naphthyl ether (manufactured by Takemoto Yushi Co., Ltd.) 400 parts and ion-exchanged water 440 parts were premixed to prepare a mixed slurry. Disk type media mill DMR type (manufactured by Ashizawa Finetech Co., Ltd.), using zirconia beads with a diameter of 0.05 mm (filling rate 55%), mixed slurry for 3 minutes at a peripheral speed of 10 m/s and a liquid temperature of 10°C. Was circulated and dispersed. Next, the coarse particles were centrifuged with a centrifuge Model-7700 (manufactured by Kubota Corporation) to obtain a pigment dispersion PD-1 having a pigment concentration of 16% by mass.

[Pigment Dispersion PD-2 (Cyan)]
Pigment Dispersion PD-2 having a pigment concentration of 16% by mass in the same manner as Pigment Dispersion PD-1 except that carbon black was changed to Pigment Blue 15:3 Chromofine Blue (manufactured by Dainichiseika Co., Ltd.). Got

[Pigment Dispersion PD-3 (Magenta)]
Pigment Dispersion PD-3 having a pigment concentration of 16% by mass was obtained in the same manner as Pigment Dispersion PD-1 except that the carbon black was changed to Pigment Red 122 toner Magenta EO02 (manufactured by Clariant).

[Pigment Dispersion PD-4 (Yellow)]
Pigment Dispersion PD-4 having a pigment concentration of 16% by mass was obtained in the same manner as Pigment Dispersion PD-1 except that the carbon black was changed to Pigment Yellow 74 First Yellow 531 (manufactured by Dainichiseika Co., Ltd.). It was

[Ink I-1]
25.00 parts of pigment dispersion PD-2, 40.00 parts of 3-ethyl-3-hydroxymethyloxetane, 2.00 parts of silicone surfactant TEGO Wet 270 (manufactured by Tomoe Kogyo Co., Ltd.) and 33.00. Part of ion-exchanged water was mixed, stirred for 1 hour, and then filtered through a membrane filter having a pore size of 1.2 μm to obtain ink I-1.

[Ink I-2]
4.00 parts of dye (cyan) Project Fast Cyan 2 (manufactured by Zeneca), 40.00 parts of 3-ethyl-3-hydroxymethyloxetane and 56.00 parts of ion-exchanged water were mixed and stirred for 1 hour. Then, it was filtered with a membrane filter having a pore size of 1.2 μm to obtain ink I-2.

[Ink I-3]
50.00 parts of pigment dispersion PD-1, 30.00 parts of 3-ethyl-3-hydroxymethyl oxetane, 2.00 parts of silicone surfactant TEGO Wet 270 (manufactured by Tomoe Kogyo Co., Ltd.) and 18.00. Part of ion-exchanged water was mixed, stirred for 1 hour, and then filtered through a membrane filter having a pore size of 1.2 μm to obtain ink I-3.

[Ink I-4]
Ink I-4 was obtained in the same manner as Ink I-3, except that Pigment Dispersion PD-1 was changed to Pigment Dispersion PD-3.

[Ink I-5]
25.00 parts of pigment dispersion PD-4, 25.00 parts of 3-ethyl-3-hydroxymethyloxetane, 20.00 parts of 1,3-butanediol, 2.00 parts of silicone surfactant TEGO Wet 270 (manufactured by Tomoe Kogyo Co., Ltd.) and 28.00 parts of ion-exchanged water were mixed, stirred for 1 hour, and then filtered through a membrane filter having a pore size of 1.2 μm to obtain Ink I-5.

Table 1 shows the types and colors of the coloring materials used in the ink.

[Resin emulsion P-1 (silicon modified acrylic resin)]
After thoroughly replacing the inside of the flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube and a dropping funnel with nitrogen gas, 100 g of pure water, 3 g of sodium dodecylbenzenesulfonate and 1 g of polyethylene glycol nonylphenyl ether were added. After charging, 1 g of ammonium persulfate and 0.2 g of sodium hydrogen sulfite were added, and the temperature was raised to 60°C. Then, a mixture of 30 g of butyl acrylate, 40 g of methyl methacrylate, 19 g of butyl methacrylate, 10 g of potassium salt of vinylsilanetriol and 1 g of 3-methacryloxypropylmethyldimethoxysilane was dropped into the flask over 3 hours to polymerize the resin. Emulsion P-1 was obtained. At this time, the pH of the polymerization reaction liquid was adjusted to 7 with an aqueous ammonia solution to carry out polymerization. The average particle diameter of the resin emulsion P-1 measured using Microtrac UPA was 160 nm. The solid content concentration of the resin emulsion P-1 was 30% by mass.

[Coating liquid A-1]
Polyethylene (PE) wax emulsion AQUACER (registered trademark) 531 (manufactured by BYK Chemie Japan) having a nonvolatile content of 45% by mass was used as a coating liquid A-1. Here, the melting point of PE wax is 130°C.

[Coating liquid A-2]
50.0 parts of modified polypropylene (PP) wax emulsion AQUACER (registered trademark) 593 (manufactured by Big Chemie Japan) having a nonvolatile content of 30% by mass and 50.0 parts of resin emulsion P-1 were mixed and stirred for 1 hour. Then, a coating liquid A-2 was obtained. Here, the modified PP wax has a melting point of 110°C.

[Coating liquid A-3]
The resin emulsion P-1 was used as the coating liquid A-3.

[Coating liquid A-4]
An aqueous dispersion of silica spherical fine particles having a solid content of 20% by mass, Seahoster (registered trademark) KE-W30 (manufactured by Nippon Shokubai Co., Ltd.) was used as a coating liquid A-4.

[Coating liquid A-5]
Highly pure water containing no powder was used as coating solution A-5.

Table 2 shows the formulation of the coating liquid.

(Example 1)
Ink I-1 was filled in an inkjet printer IPSiO GX5000 (manufactured by Ricoh Co., Ltd.) as an image forming apparatus in an environment of 23° C. and 50% RH. Next, by printing a chart in which the general symbols of JIS X 0208 (1997) and 2223 of 64 point and 128 point created by Microsoft Word 2000 (manufactured by Microsoft Corporation) are printed, the ink I- is formed on the recording medium by the liquid ejection head. 1 was applied.

At this time, change the print mode from "Glossy paper-Standard clean" mode to "No color correction" or "Glossy paper-Standard fast" mode from the user setting of glossy paper in the driver attached to the printer. The mode was changed to "no color correction".

As a recording medium, Lumiart Gloss 90 gsm (manufactured by MONDI Color Copy Co., Ltd.) (hereinafter, referred to as coated paper 1) or OK Top Coat having a basis weight of 73.3 g/cm ² + (manufactured by Oji Paper Co., Ltd.) Coated paper 2) was used. Further, the general symbol of JIS X 0208 (1997), 2223 is a symbol whose outer shape is square and whose entire surface is filled.

10 seconds after the printing is completed, the heated air and the coating liquid A-1 are sent to a mini atomizing nozzle MMA-10 (manufactured by Everloy Trading Co., Ltd.), which is a two-fluid nozzle as a spray nozzle (sprayer), and is vertically applied from the recording medium. The coating liquid A-1 was applied by spraying onto the printing surface of the recording medium from a position 30 cm away in the direction. At this time, the scanning speed of the spray nozzle (relative speed between the recording medium and the spray nozzle) was adjusted so that the coating amount of the coating liquid A-1 was 100 mg per A4 size.

The heated air is generated by a hot air generator HAP4020 (manufactured by Yako Denki Co., Ltd.), and the temperature just before being mixed with the coating liquid by the spray nozzle is the tip welding type, K-type thermoelectric with a wire diameter of 0.2 mm. It was measured with a pair (manufactured by Three High Co.). At this time, the set temperature of the hot air generator was adjusted so that the temperature of the air was 140°C. Further, the amount of the coating liquid sent to the spray nozzle was adjusted to 10 mL/min.

Further, 30 seconds after the application of the coating liquid was completed, warm air was blown onto the recording medium for 1 minute using a dryer to heat the recording medium. At this time, the wind speed of the dryer was set to 20 m/s. As a result, the temperature of the recording medium during heating was 100°C. The temperature of the recording medium during heating was measured by bringing a K-type thermocouple (manufactured by Three High Co., Ltd.) having a wire diameter of 0.2 mm into contact with the recording medium.

(Example 2)
An image was formed in the same manner as in Example 1 except that the ink I-3 was used in place of the ink I-1, and the coating liquid A-2 was used in place of the coating liquid A-1.

(Examples 3 and 4)
An image was formed in the same manner as in Example 1 except that Ink I-4 in Example 3 and Ink I-5 in Example 4 were used instead of Ink I-1.

(Example 5)
An image was formed in the same manner as in Example 1 except that Ink I-2 was used instead of Ink I-1.

(Example 6)
An image was formed in the same manner as in Example 1 except that the recording medium was not heated after the coating liquid A-1 was applied.

(Example 7)
An image was formed in the same manner as in Example 1 except that the gas sent to the spray nozzle when applying the coating liquid A-1 was changed from air to nitrogen.

(Example 8)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was lowered and the temperature of the air introduced into the spray nozzle was adjusted to 50°C.

(Example 9)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was lowered and the temperature of the air introduced into the spray nozzle was adjusted to 60°C.

(Example 10)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was raised and the temperature of the air introduced into the spray nozzle was adjusted to 200°C.

(Example 11)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was increased and the temperature of the air introduced into the spray nozzle was adjusted to 220°C.

(Examples 12 and 13)
An image was formed in the same manner as in Example 1 except that the coating liquid A-3 was used in Example 12 and the coating liquid A-4 was used in Example 13 instead of the coating liquid A-1.

(Example 14)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was increased and the temperature of the air introduced into the spray nozzle was adjusted to 350°C.

(Comparative Example 1)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was lowered and the temperature of the air introduced into the spray nozzle was adjusted to 40°C.

(Comparative example 2)
An image was formed in the same manner as in Example 1 except that the coating liquid A-5 was used instead of the coating liquid A-1.

(Comparative example 3)
An image was formed in the same manner as in Example 1 except that the coating liquid A-5 was used instead of the coating liquid A-1.

(Comparative Example 4)
An image was formed in the same manner as in Example 1 except that the heating set temperature of the warm air generator was increased and the temperature of the air introduced into the spray nozzle was adjusted to 400°C.

Table 3 shows the image forming conditions of Examples and Comparative Examples.

(Evaluation)
Next, the image density, image glossiness, fixability, blocking resistance, and paper expansion/contraction were evaluated. In any of the evaluations, AA, A, and B were passed, and C was not passed.

<Image density>
Using X-Rite 938 (manufactured by X-Rite Co., Ltd.), the image density of the area of the recording medium where the general symbol of 64 points was printed was measured. At this time, the print mode is set to a mode in which the "glossy paper-standard clean" mode is changed to "no color correction" from the user setting of glossy paper in the driver attached to the printer, and the coated paper 1 is used as the recording medium. Using.

The image density was judged according to the following evaluation criteria.

[Evaluation criteria]
Black ink AA: 2.00 or more A: 1.90 or more and less than 2.00 B: 1.80 or more and less than 1.90 C: less than 1.80 Cyan ink AA: 2.00 or more A: 1.90 or more 2. Less than 00 B: 1.80 to less than 1.90 C: less than 1.80 Magenta ink AA: 1.90 or more A: 1.80 to less than 1.90 B: 1.70 to less than 1.80 C: 1. Less than 70 Yellow ink AA: 1.00 or more A: 0.90 or more but less than 1.00 B: 0.80 or more but less than 0.90 C: less than 0.80 <Image glossiness>
Using a handy gloss meter PC-IIM type (manufactured by Nippon Denshoku Industries Co., Ltd.), the 60° glossiness of the area of the recording medium on which the 128-point general symbol is printed was measured. At this time, the print mode is set to a mode in which the "glossy paper-standard clean" mode is changed to "no color correction" from the user setting of glossy paper in the driver attached to the printer, and the coated paper 1 is used as the recording medium. Using.

The image glossiness was judged according to the following evaluation criteria.

〔Evaluation criteria〕
AA:30 or more A: 25 or more and less than 30 B: 20 or more and less than 25 C: less than 20 <Fixability 1>
The area of the recording medium on which the 128-point JIS X 0208 (1997), 2223 general symbol is printed is the same as the recording medium used for printing, and is rubbed 10 times with an unprinted recording medium and is not printed. The degree of transfer of the pigment to the recording medium was visually observed to evaluate the fixability. At this time, the print mode is set to a mode in which the "glossy paper-standard clean" mode is changed to "no color correction" from the user setting of glossy paper in the driver attached to the printer, and the coated paper 1 is used as the recording medium. Using.

The fixability was evaluated according to the following evaluation criteria.

〔Evaluation criteria〕
A: Almost no transfer of the pigment to the recording medium was observed. B: Slight transfer of the pigment to the recording medium was observed (area less than 10% of the whole).
C: The transfer of pigment to the recording medium is clearly seen (10% or more of the total area).
<Fixability 2>
Fixability 2 was evaluated in the same manner as Fixability 1 except that coated paper 2 was used as the recording medium.

<Fixability 3>
In the same manner as in Fixability 1, except that the printing mode is changed from "Glossy paper-standard fast" mode to "No color correction" from the user setting of glossy paper in the driver attached to the printer, Fixability 3 was evaluated.

<Blocking resistance 1>
An area in which a 128-point JIS X 0208 (1997), 2223 general symbol of the recording medium is printed is the same as the recording medium used for printing 3 minutes after the image is formed, and is not printed. (4 cm×4 cm) were stacked, and a rubber sheet having a length of 2 cm×a width of 2 cm×a thickness of 0.2 cm was placed on the center of the recording medium. Next, a weight was placed on the rubber sheet so that the pressure applied from the rubber sheet to the recording medium would be 0.5 kgf/cm ^2, and left for 12 hours in an environment of 23° C. and 50% RH. Further, the stacked recording media were peeled off, and the degree of transfer of the pigment to the non-printed recording media was visually observed to evaluate the blocking resistance. At this time, the print mode is set to a mode in which the "glossy paper-standard clean" mode is changed to "no color correction" from the user setting of glossy paper in the driver attached to the printer, and the coated paper 1 is used as the recording medium. Using.

The blocking resistance was judged according to the following evaluation criteria.

〔Evaluation criteria〕
A: Almost no transfer of the pigment to the recording medium is observed.

B: Slight transfer of pigment to recording medium is observed (less than 10% of the total area)
C: The transfer of pigment to the recording medium is clearly seen (10% or more of the total area).
<Blocking resistance 2>
Blocking resistance 2 was evaluated in the same manner as blocking resistance 1 except that coated paper 2 was used as the recording medium.

<Paper stretch>
After measuring the length of the short side of the A4 size recording medium, a 512 point JIS X 0208 (1997), 2223 general symbol was printed on the center of the recording medium to form an image. After printing, the length of the short side of the recording medium was measured again to evaluate the expansion and contraction of the paper. At this time, the print mode is set to a mode in which the "glossy paper-standard clean" mode is changed to "no color correction" from the user setting of glossy paper in the driver attached to the printer, and the coated paper 1 is used as the recording medium. Using.

The expansion and contraction of the paper was judged according to the following evaluation criteria.

〔Evaluation criteria〕
A: The amount of change in the length of the short side of the recording medium is -0.10 mm or more and 0.10 mm or less.

B: The amount of change in the length of the short side of the recording medium is less than −0.10 mm −0.50 mm or more, or more than 0.10 mm and 0.50 mm or less.

C: The amount of change in the length of the short side of the recording medium is less than −0.50 mm or more than 0.50 mm.

Table 4 shows the evaluation results of the image density, the image glossiness, the fixability, the blocking resistance, and the paper expansion and contraction.

From Table 4, Examples 1 to 14 are AA, A, or B in any evaluation, and an image excellent in image density, image glossiness, fixability and blocking resistance is formed on the coated paper, and the paper stretches. It turns out that can be suppressed.

On the other hand, in Comparative Example 1, since the temperature of the air supplied to the spray nozzle is low, the fixability and blocking resistance of the image formed on the coated paper are poor. Further, in Comparative Example 2, since the coating liquid does not contain powdery substances or wax, the fixability and blocking resistance of the image formed on the coated paper are poor. In Comparative Example 3, since the coating liquid A-1 was not applied, the image density, the image glossiness, the fixability and the blocking resistance of the image formed on the coated paper were poor, and the expansion and contraction of the paper was large. In Comparative Example 4, the temperature of the air introduced into the spray nozzle was too high to damage the coated paper, so that each evaluation could not be performed (indicated as "-" in Table 4).

Although the preferred embodiments and the like have been described above in detail, the present invention is not limited to the above-described embodiments and the like, and various embodiments and the like described above can be performed without departing from the scope described in the claims. Modifications and substitutions can be added.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Liquid ejection head 20 Spraying device 21 Sprayer 22 Warm air generator 23 Temperature detection means 211 Liquid introduction path 212 Gas introduction path 213 Nozzle

JP 2012-213906A

Claims (7)

Applying a first liquid used for image formation to an object to be ejected by a liquid ejection head;
A second liquid containing at least one of a water-soluble wax and a water-dispersible wax is sprayed on the surface of the ejection target object on the side where the first liquid is applied together with air at 60° C. or higher and 140° C. or lower by a spraying device The step of spraying,
And a step of heating the discharge target after the step of spraying with the spray device. The image forming method according to claim 1, wherein a pigment having at least one kind of anionic hydrophilic group is used as the coloring material of the first liquid. The pigment is a first pigment dispersed by a dispersant having at least one anionic hydrophilic group, a second pigment coated with a resin having at least one anionic hydrophilic group, and at least one anion. 3. The image forming method according to claim 2, further comprising an atomic group containing a hydrophilic hydrophilic group or a third pigment having a resin having at least one kind of anionic hydrophilic group bonded thereto. .. The image forming method according to claim 1, wherein the content of water in the first liquid is 20 to 60 mass %. A liquid ejection head for applying a first liquid used for image formation to an ejection target;
A spray for spraying a second liquid containing at least one of a water-soluble wax and a water-dispersible wax on the surface of the ejection target object on the side where the first liquid is applied together with air at 60° C. or higher and 140° C. or lower. And a device,
The spraying device is
A nozzle for spraying a liquid introduction passage, a gas introduction passage, and a second liquid containing at least one of a water-soluble wax and a water dispersible wax introduced into the liquid introduction passage together with air introduced into the gas introduction passage, An image forming apparatus having a sprayer provided with . The image forming apparatus according to claim 5, wherein the spray device includes a warm air generator that introduces air of 60° C. or higher and 140° C. or lower into the gas introduction path. The spraying device is
The image forming apparatus according to claim 6, further comprising a temperature detection unit that detects the temperature of the gas introduced into the gas introduction path and outputs the detection result to the warm air generator.