JP5499522B2 - Inkjet recording apparatus and inkjet recording method - Google Patents

Description

  The present invention relates to a radiation curable ink jet recording method using a radiation curable ink that is cured by irradiation with radiation such as ultraviolet rays.

  An ultraviolet curable ink is known as an ink used when ink-jet printing is performed on a non-absorbing medium (for example, coated paper, resin, metal, glass, etc.) that does not absorb ink. Unlike an ink using a volatile organic solvent, an ultraviolet curable ink that is cured and fixed by irradiation with ultraviolet rays does not require electric power for evaporating or volatilizing the solvent contained in the ink. For this reason, it has the characteristics that productivity of printed matter is high and power consumption can be kept low. In addition, the cured UV curable ink has a glossy surface, so even if it is printed on a glossy medium such as coated paper, it is possible to form an image with no discomfort between the printed part and the non-printed part. is there.

On the other hand, when UV curable ink is used when printing on glossy recording media such as plain paper, the difference in gloss between the printed part and the non-printed part is large, so that only the image feels floating from the background. There's a problem. Therefore, for non-glossy recording media, after forming an image, the entire or part of the surface of the recording medium is glossed by undercoating or overcoating, or the background is filled with white ink. It is necessary to reduce the gloss difference from the non-printed part. However, the above-described processing method has a problem that the amount of ink used increases and the production cost of printed matter increases.
Patent Document 1 is cited as a document describing an ink jet recording method for controlling the glossiness of the image surface. In Patent Document 1, ultraviolet irradiation with respect to the ultraviolet curable ink landed on the surface of the recording material (non-absorbing medium) is performed in two portions, and the recording medium (base material) is adjusted by adjusting the interval of ultraviolet irradiation. The glossiness of the image surface is controlled according to the image quality.

However, the inkjet recording method described in Patent Document 1 requires about 0.5 seconds to 3 minutes until the second irradiation, so that the productivity is poor, and it is not suitable for high-speed printing, and the printing apparatus is increased in size. There is a problem.
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to perform UV printing that does not give a sense of incongruity even when printing is performed using ultraviolet curable ink on plain paper at high speed and with high productivity.

In order to solve the above-described problems, the invention described in claim 1 includes a transport unit that transports a recording medium, a print head that discharges radiation-curable ink onto the recording medium transported by the transport unit, and a recording The first radiation irradiating means for curing the inside of the landing ink landed on the medium by radiation irradiation, the roughening member for transferring the shape of the rough surface to the surface of the landing ink cured inside, and the rough surface were transferred Second radiation irradiating means for curing the landing ink surface by radiation irradiation, the surface roughness of the roughening member is set to be larger than the surface roughness of the recording medium, and the second radiation irradiating means is The recording medium is configured to move forward and backward in the recording medium conveyance direction, and is based on the temporal change in the surface roughness of the rough surface transferred to the surface of the landing ink and the conveyance speed of the recording medium by the conveyance means. Te, and wherein the ink jet recording apparatus to set the distance between the the roughened member said second radiation means.
請 Motomeko invention described in 2, the recording medium discharged radiation-curable ink radiation given of the recording medium fused to a radiation curable ink jet recording an image on a conveyed at the conveying speed by irradiating the a method, a first radiation curing the internal landing ink landed on the recording medium by irradiating a radiation on the surface of the landing ink inside is cured in the first irradiation step, the recording A roughening step of transferring the rough surface by a roughening member having a surface roughness larger than the surface roughness of the medium, and a second surface of the landing ink to which the rough surface has been transferred is cured by a second radiation irradiation means . a radiation irradiating step, was closed, and further, the temporal change surface roughness of the rough surface of which has been transferred to the surface of the landing ink, based on the transport speed of the recording medium, wherein the roughened portion Characterized by having a step of setting a distance between said second radiation means.
The invention according to claim 3 is characterized in that the recording medium is ink-absorbing and the surface roughness of the roughening member is within + 30% of the surface roughness of the recording medium.

  According to the present invention, only the inside of the radiation curable ink discharged onto the recording medium is cured by the first radiation irradiating means, and the roughening member is pressed against the surface of the uncured radiation curable ink. Since the roughened surface is transferred and roughened, and the roughened radiation curable ink is cured by the second radiation irradiating means, the glossiness of the image can be controlled at high speed and with high productivity.

It is the schematic diagram which showed the principal part of the inkjet recording device. It is an expanded sectional view of a roughening member. It is an expanded sectional view of the landing ink before roughening. It is an expanded sectional view of the landing ink after roughening. It is a figure which shows with the graph which shows the example of the time change of the arithmetic mean roughness of the rough surface transcribe | transferred to the landing ink non-hardened part. FIG. 4 is a perspective explanatory view showing a state where an ink cartridge loading unit cover of the ink jet recording apparatus is opened. It is a schematic block diagram explaining the whole structure of an inkjet recording device. It is a schematic enlarged view which shows an example of an inkjet head (printing head).

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a schematic view showing a main part of an ink jet recording apparatus according to the present invention. FIG. 2 is an enlarged cross-sectional view of the roughening member. FIG. 3 is an enlarged cross-sectional view of the landing ink before roughening. FIG. 4 is an enlarged cross-sectional view of the landing ink after the roughening. In this specification, the term “radiation” is used in a broad sense, that is, various particle beams and radiation rays.
The inkjet recording apparatus 1 using the ultraviolet curing system includes a print head 10 that sequentially discharges ink dots 30 of ultraviolet curable ink toward the recording medium 20 being conveyed in order from the upstream side toward the downstream side in the conveyance direction of the recording medium 20. The first ultraviolet irradiation means 40 (first radiation irradiation means) for curing the ink inside 31a of the landing ink 31 by irradiating the landing ink 31 landed on the recording medium 20 with ultraviolet rays, and the ink inside 31a is cured. A roller-like roughening member 50 that presses the landed ink 31 to transfer the shape of the rough surface 51 to the ink surface 31b, and a roller that is disposed opposite the roughening member 50 across the conveyance path of the recording medium 20. The ink surface 31b of the landing ink 31 is irradiated with ultraviolet rays to the surface facing member 52 and the landing ink 31 roughened by the roughening member 50. A second ultraviolet light irradiation means 60 is cured (the second irradiation means) is disposed.

The ink used in the inkjet recording apparatus 1 is ultraviolet curable ink (radiation curable ink) that is cured by irradiation with radiation such as ultraviolet rays.
A piezo type, a thermal type, a bubble jet (registered trademark) type, an electromagnetic valve type, or the like can be used for the print head 10. The print head 10 ejects ink dots 30, and an aggregate of dot-like landing inks 31 that have landed on the recording medium 20 forms an image 32.
As the first ultraviolet irradiation means 40 and the second ultraviolet irradiation means 60, a mercury lamp, a metal halide lamp, an excimer lamp, an ultraviolet laser, an ultraviolet LED, or the like can be used. The second ultraviolet irradiation means 60 is configured to be movable back and forth in the recording medium conveyance direction.
The first ultraviolet irradiation means 40 and the second ultraviolet irradiation means 60 generate radicals (active species) from the polymerization initiator contained in the ultraviolet curable ink by ultraviolet energy. When radicals react with oxygen in the air, the radicals are reduced and the activity is lost, so that the polymerization rate is slowed down on the ink surface 31b. On the other hand, radicals are not reduced by oxygen in the air inside the ink 31a, and the ultraviolet intensity is sufficiently strong, so that the curability is better than that of the ink surface 31b. Therefore, in the present invention, the ink interior 31 a is cured by the first ultraviolet irradiation means 40, and the ink surface 31 b is cured by the second ultraviolet irradiation means 60.

The roughening member 50 is a roller-shaped member in which a silicon rubber layer is coated on the surface of a base material made of SUS. Not only the roller shape but also various shapes such as a belt shape and a flat plate shape can be used. The silicon rubber surface has a rough surface 51 having an arithmetic average roughness Ra (surface roughness) slightly larger than the arithmetic average roughness Ra (surface roughness) of the surface of the recording medium 20. Since the ink before curing has fluidity, it is considered that the rough surface shape transferred to the ink surface 31b is gradually restored to a flat surface. Here, when the recording medium 20 is a water-absorbing medium that absorbs ink, such as plain paper, the arithmetic average roughness of the roughening member is set to the arithmetic average of the recording medium in order to perform printing without shine and uncomfortable feeling. It is desirable to be within ± 30% of the roughness.
In this embodiment, the arithmetic average roughness (Ra) is used as the surface roughness parameter, but other parameters (maximum height: Ry, ten-point average roughness: Rz, etc.) may be used. Good.
The facing member 52 is a member made of roller-like SUS that presses the recording medium 20 with a predetermined pressure at a nip portion N formed between the facing member 50. In addition to the roller shape, various shapes such as a belt shape and a flat plate shape can be used.

A recording method using the recording apparatus 1 configured as described above will be described based on examples.
The recording apparatus 1 conveys the recording medium 20 at a speed of 210 m / min by a conveyance apparatus (not shown). As the recording medium 20, plain paper having an arithmetic average roughness of 4 μm was used.
The ultraviolet curable ink in this example is obtained by dispersing a black pigment in a colorless mixture of (meth) acrylate monomer (90 wt%) and a polymerization initiator (10 wt%) at a mixing ratio of 100: 8 (colorless mixture: black pigment). It was obtained by doing. The (meth) acrylate monomer may be a mixture of a plurality of monomers. The polymerization initiator may be a mixture of a plurality of polymerization initiators. The mixing ratio of the (meth) acrylate monomer and the polymerization initiator is an example, and is not limited thereto. Moreover, you may add a polymerization accelerator and a leveling agent to a colorless mixture suitably. The pigment of the ultraviolet curable ink is not limited to black, but may be yellow, magenta, cyan, or white. Further, the blending ratio of the colorless mixture and the pigment may not be 100: 8. You may add a dispersing agent suitably.

The print head 10 of the present embodiment is a piezo-type nozzle having a nozzle diameter of 30 μm, and metal halide lamps are used for the first ultraviolet irradiation means 40 and the second ultraviolet irradiation means 60.
Seven picoliters (pl) of ink dots 30 are ejected from the print head 10 toward the recording medium 20 to form an image 32 of an aggregate of landing inks 31 having a density of 600 dpi. , 50 mJ / cm ² of ultraviolet rays were irradiated, the ink interior 31a was cured, and only the ink surface 31b was uncured.
Further, a nip portion N formed by a roughening member 50 covered with a silicon rubber layer whose rough surface 51 is finished to an arithmetic average roughness (Ra) 5 μm slightly larger than the recording medium surface 21 and a counter member 52 made of SUS. , The shape of the rough surface 51 of the roughening member 50 is transferred to the ink surface 31b, and further, the second ultraviolet irradiation means 60 irradiates with 500 mJ / cm ² of ultraviolet rays, and the ink surface 31b is transferred to the recording medium. The arithmetic average roughness (Ra) equivalent to the surface 21 was set to 4 μm.

Here, the distance d between the roughening member 50 and the second ultraviolet irradiation means 60 will be described with reference to FIG. FIG. 5 is a graph showing an example of the change over time of the arithmetic average roughness of the rough surface transferred to the dot uncured portion. The arithmetic average roughness equal to the arithmetic average roughness of 4 μm of the recording member P is 23 ms after the pressing by the roughening member 50. Accordingly, the distance d is set so that the ultraviolet irradiation by the second ultraviolet irradiation means 60 is performed 23 ms after the recording medium 20 is pressed. Since the conveyance speed of this embodiment is 210 m / min, the distance d is set to 8 cm.
As described above, the second ultraviolet irradiation means 60 is configured to be movable back and forth in the recording medium conveyance direction. The fluidity of the ink varies depending on the temperature and the degree of curing, but an arbitrary glossiness can be obtained by appropriately adjusting the distance d. Further, when it is desired to lower the gloss level than the recording medium 20, the gloss level can be controlled by setting d short, and when increasing the gloss level, d can be set long. It is also possible to obtain a different glossiness.

Here, one aspect of carrying out the ink jet recording method of the present invention by the ink jet recording apparatus of the present invention will be described with reference to FIG. FIG. 6 is a schematic view showing an example of the ink jet recording apparatus of the present invention. The ink jet recording apparatus 1 shown in FIG. 6 includes an apparatus main body 101, a paper feed tray 102 for loading paper mounted on the apparatus main body 101, and paper on which an image is recorded (formed) mounted on the apparatus main body 101. A paper discharge tray 103 for stocking and an ink cartridge loading unit 104 are provided. On the upper surface of the ink cartridge loading unit 104, an operation unit 105 such as operation keys and a display is arranged. The ink cartridge loading unit 104 has a front cover 115 that can be opened and closed for attaching and detaching the ink cartridge 201.
In the apparatus main body 101, as shown in FIGS. 7 and 8, a carriage 133 is slid in the main scanning direction by a guide rod 131 and a stay 132, which are guide members horizontally mounted on left and right side plates (not shown). The main scanning motor (not shown) moves and scans in the direction indicated by the arrow in FIG.

The carriage 133 includes a plurality of inkjet heads 134 each composed of four inkjet inkjet heads (printing heads) that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The ink discharge ports are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet discharge direction facing downward.
As an inkjet inkjet head constituting the inkjet head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator using an electrostatic force, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.
Also, the carriage 133 is equipped with sub tanks 135 for each color for supplying ink of each color to the inkjet head 134. The sub tank 135 is supplied with each ink in the ink media set of the present invention from the ink cartridge 201 of the present invention loaded in the ink cartridge loading section 104 via an ink supply tube (not shown).

On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 102, a half-moon roller (feeding) that separates and feeds the paper 142 from the paper stacking unit 141 one by one. A separation pad 144 made of a material having a large coefficient of friction is provided facing the paper roller 143) and the paper feed roller 143, and the separation pad 144 is urged toward the paper feed roller 143 side.
As a transport unit for transporting the paper 142 fed from the paper feed unit below the inkjet head 134, a transport belt 151 for transporting the paper 142 by electrostatic adsorption and a guide 145 from the paper feed unit. The counter roller 152 for transporting the paper 142 fed via the transport belt 151 with the transport belt 151 and the paper 142 fed substantially vertically upward are changed by approximately 90 ° so as to follow the transport belt 151. A conveying guide 153 and a tip pressure roller 155 urged toward the conveying belt 151 by a pressing member 154, and a charging roller 156 as a charging means for charging the surface of the conveying belt 151. It has been.

The conveyance belt 151 is an endless belt, is stretched between the conveyance roller 157 and the tension roller 158, and can circulate in the belt conveyance direction. The transport belt 151 includes, for example, a surface layer serving as a sheet adsorption surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), and the same surface layer. It has a back layer (medium resistance layer, earth layer) that has been subjected to resistance control with carbon as a material.
On the back side of the conveyance belt 151, a guide member 161 is disposed corresponding to a printing area by the inkjet head 134. Note that a separation claw 171 for separating the paper 142 from the transport belt 151, a paper discharge roller 172, and a paper discharge roller 173 are provided as a paper discharge unit for discharging the paper 142 recorded by the inkjet head 134. The paper discharge tray 103 is disposed below the paper discharge roller 172.
A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101. The double-sided paper feeding unit 181 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 152 and the transport belt 151. A manual paper feed unit 182 is provided on the upper surface of the duplex paper feed unit 181.

In this ink jet recording apparatus, the paper 142 is separated and fed one by one from the paper feed unit, and the paper 142 fed substantially vertically upward is guided by the guide 145 and between the transport belt 151 and the counter roller 152. It is sandwiched and conveyed. Further, the leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure roller 155, and the conveying direction is changed by approximately 90 °.
At this time, the conveying belt 151 is charged by the charging roller 156, and the sheet 142 is electrostatically attracted to the conveying belt 151 and conveyed. Therefore, by driving the inkjet head 134 according to the image signal while moving the carriage 133, the ink droplets are ejected onto the stopped paper 142 to record one line, and after the paper 142 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 142 has reached the recording area, the recording operation is terminated and the sheet 142 is discharged onto the discharge tray 103.
When a near-end remaining amount of ink in the sub tank 135 is detected, a required amount of ink is supplied from the ink cartridge 201 to the sub tank 135.

In this ink jet recording apparatus, when the ink in the ink cartridge 201 of the present invention is used up, the casing of the ink cartridge 201 can be disassembled and only the ink bag inside can be replaced. Further, the ink cartridge 201 can supply ink stably even when the ink cartridge 201 is placed vertically and has a front loading configuration. Therefore, when the upper portion of the apparatus main body 101 is closed and installed, for example, even when the apparatus main body 101 is stored in a rack or an object is placed on the upper surface of the apparatus main body 101, the ink cartridge 201 is replaced. Can be easily performed.
Here, an example is described in which the present invention is applied to a serial (shuttle type) ink jet recording apparatus that is scanned by a carriage.

Further, in the ink jet recording apparatus and the ink jet recording method of the present invention, when printing is performed at a high printing speed, the recording apparatus is not stained with ink that may be generated due to insufficient drying of the ink after recording. In order to avoid offset contamination on the recording medium, drying accelerating means (also referred to as a drying device) can be used in the apparatus such as a printer or outside. Drying promotion means includes only a blowing means without a special heat generation source, only a heat generation source such as a halogen lamp or other heater, a combination of a heat generation source and a blowing means, a microwave drying device Etc. are preferably applicable.
The ink jet recording apparatus and the ink jet recording method of the present invention can be applied to various types of recording by the ink jet recording method, and are particularly suitable for, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, and a printer / fax / copier multifunction machine. Can be applied to.

  DESCRIPTION OF SYMBOLS 1 ... Recording device, 10 ... Print head, 20 ... Recording medium, 21 ... Recording medium surface, 30 ... Ink dot, 31 ... Landing ink, 31a ... Inside ink, 31b ... Ink surface, 32 ... Image, 40 ... First UV irradiation means, 50 ... roughening member, 51 ... rough surface, 52 ... opposing member, 60 ... second ultraviolet irradiation means, N ... nip part

JP 2003-211651 A

Claims (3)

A transport unit configured to transport a recording medium; a print head that discharges radiation-curable ink onto the recording medium transported by the transport unit; and a first radiation that cures the interior of the landed ink landed on the recording medium by radiation irradiation. Irradiation means, a roughening member that transfers the shape of the rough surface to the surface of the landing ink that has been cured inside, and a second radiation irradiation means that cures the landing ink surface to which the rough surface has been transferred by radiation irradiation. Prepared ,
The surface roughness of the roughening member is set larger than the surface roughness of the recording medium,
The second radiation irradiating means is configured to be movable back and forth in the recording medium transport direction,
Based on the temporal change in surface roughness of the rough surface transferred to the surface of the landing ink and the transport speed of the recording medium by the transport means, the roughening member and the second radiation irradiating means An ink jet recording apparatus that sets a distance between the two . A radiation curable ink jet recording method for fixing an image on the recording medium transported at a predetermined transport speed by irradiating radiation curable ink discharged on the recording medium with a radiation,
A first radiation irradiation step of curing the inside of the landing ink landed on the recording medium by irradiating with radiation;
A roughening step of transferring a rough surface to the surface of the landing ink whose inside has been cured in the first radiation irradiation step by a roughening member having a surface roughness larger than the surface roughness of the recording medium ;
The landing ink surface the rough surface is transferred, a second irradiation step of curing the second radiation emitting means, the possess,
Further, based on the temporal change in the surface roughness of the rough surface transferred to the surface of the landing ink and the conveyance speed of the recording medium, the surface between the roughening member and the second radiation irradiating means. An ink jet recording method comprising the step of: 3. The ink jet recording method according to claim 2, wherein the recording medium is water-absorbing and the surface roughness of the roughening member is within + 30% of the surface roughness of the recording medium.

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