JP2015051553A - Image formation method and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation method and an image formation device each capable of inhibiting bleeding and the generation of a residual liquid appearance.SOLUTION: The provided image formation method includes a step of applying a first solvent S atop an elastic member E, a step of adhering ink drops D onto the first solvent S applied atop the elastic member E by jetting an inkjet ink, and a step of transferring, to a plain paper P, the ink drops D adhered to the first solvent S; the inkjet ink includes a second solvent and a resin and a coloring material dissolved into the second solvent; the first solvent S is capable of inducing the deposition of the resin when the inkjet ink is dropped thereon; the second solvent can be blended with the first solvent S; and the surface of the elastic member E on the side coated with the first solvent S is a rough surface.

Description

  The present invention relates to an image forming method and an image forming apparatus.

  Ink jet ink generally tends to bleed when attached to a recording medium. For example, when ink-jet ink adheres to plain paper, the ink-jet ink diffuses along the fiber lines of pulp, and bleeding tends to occur. When ink jet ink bleeding occurs, the image density decreases and the edge of the image is blurred, which causes image deterioration.

Patent Document 1 discloses an oil-based inkjet printing method in which printing is performed by applying a pretreatment liquid to a print medium and then discharging an oil-based ink containing at least a pigment and a solvent onto the print medium. At this time, the pretreatment liquid includes at least inorganic particles having an average particle diameter of 1 μm or more and 20 μm or less and a solvent, and the solubility parameter (SP value) of the solvent of the pretreatment liquid and the solubility parameter (SP value) of the solvent of the oil-based ink. ) Is 1.0 (cal / cm ³ ) ^1/2 or more.

  However, there is a problem that a feeling of residual liquid occurs.

  An object of one embodiment of the present invention is to provide an image forming method and an image forming apparatus capable of suppressing the occurrence of bleeding and a feeling of residual liquid in view of the problems of the related art.

  In one embodiment of the present invention, in the image forming method, a step of applying a first solvent to the intermediate transfer member, and a step of discharging an inkjet ink to adhere to the first solvent applied to the intermediate transfer member; A step of transferring the ink-jet ink attached to the first solvent to a recording medium, the ink-jet ink comprising a second solvent, a resin dissolved in the second solvent, and a coloring material, The first solvent is capable of precipitating the resin when the inkjet ink is dropped, and the second solvent is miscible with the first solvent. The surface on which the first solvent is applied is rough.

  According to one embodiment of the present invention, in an image forming apparatus, an intermediate transfer member, a coating unit that applies a first solvent to the intermediate transfer member, and a first ink that is applied to the intermediate transfer member by ejecting inkjet ink. And a transfer means for transferring the ink-jet ink attached to the first solvent to a recording medium. The ink-jet ink is dissolved in the second solvent and the second solvent. The first solvent is capable of precipitating the resin when the inkjet ink is dropped, and the second solvent is miscible with the first solvent. The intermediate transfer member has a rough surface on the side on which the first solvent is applied.

  According to one embodiment of the present invention, it is possible to provide an image forming method and an image forming apparatus capable of suppressing the occurrence of bleeding and residual liquid feeling.

It is a schematic diagram explaining an example of an image forming method. It is a schematic diagram which shows 1st embodiment of the elastic member of FIG. It is a schematic diagram which shows 2nd embodiment of the elastic member of FIG. It is a schematic diagram which shows the state immediately after the ink droplet which followed the 1st solvent apply | coated to the elastic member of FIG. 3 adhered. It is a schematic diagram which shows the ink droplet with which the viscosity produced | generated to the elastic member of FIG. 3 increased. It is a schematic diagram which shows the state immediately after the ink droplet which followed the 1st solvent apply | coated to the elastic member to which the surface is not provided with roughness adheres. It is a schematic diagram which shows the ink droplet with which the viscosity produced | generated to the elastic member to which the surface was not provided with the roughness increased. It is a schematic diagram which shows an example of the manufacturing method of the elastic member of FIG. It is a schematic diagram which shows the other example of the manufacturing method of the elastic member of FIG. 1 is a schematic diagram illustrating a first embodiment of an image forming apparatus. It is a schematic diagram which shows the modification of the image forming apparatus of FIG. It is a schematic diagram which shows 2nd embodiment of the image forming apparatus of this invention. FIG. 13 is a schematic diagram illustrating a modification of the image forming apparatus in FIG. 12. 4 is an optical micrograph of the surface of the intermediate transfer roller 2-1 on the side to which the first solvent is applied. 4 is an optical micrograph of the surface of the intermediate transfer roller 2-2 on the side to which the first solvent is applied. It is an optical microscope photograph of the image of Example 2-1. It is an optical microscope photograph of the image of Example 2-2. It is an optical microscope photograph of the image of Comparative Example 2-1.

  Next, the form for implementing this invention is demonstrated with drawing.

  An example of an image forming method will be described with reference to FIG.

  First, the coating member 12 in which the sponge 12b impregnated with the first solvent S is fixed to the support plate 12a is moved on the elastic member E as an intermediate transfer member, and the first solvent S is applied to the entire surface of the elastic member E. Is applied (see FIG. 1A).

  Next, inkjet ink is discharged, and the ink droplet D is made to adhere to the 1st solvent S apply | coated to the elastic member E (refer FIG.1 (b)). At this time, the inkjet ink includes a second solvent, a resin and a colorant dissolved in the second solvent, and the first solvent S can deposit the resin when the inkjet ink I is dropped. It is. The second solvent can be mixed with the first solvent S.

  As soon as the ink droplet D adheres to the first solvent S, the second solvent in the ink droplet D diffuses into the first solvent S, so that the first solvent and the second solvent are mixed. S ′, and ink droplets D ′ having increased viscosity are generated (see FIG. 1C). At that time, since the resin in the ink droplet D is not dissolved in the first solvent S, the resin and the coloring material are difficult to diffuse into the first solvent S. For this reason, it becomes difficult for the resin and the color material in the ink droplet D ′ having increased viscosity to diffuse.

  Further, the ink droplet D ′ having increased viscosity is transferred to the plain paper P as a recording medium (see FIG. 1D). The ink droplet D ′ having increased viscosity is easily transferred because the mixed solvent S ′ between the elastic member E and the elastic member E serves as a shielding layer. At this time, the ink droplets D ′ having increased viscosity transferred to the plain paper P are less likely to diffuse resin and color material, so that the occurrence of bleeding can be further suppressed. Thereafter, the mixed solvent S ′ remaining in the ink droplet D ′ having increased viscosity transferred to the plain paper P evaporates or diffuses into the plain paper P, and the resin and color in the ink droplet D ′ having increased viscosity Since the material remains on the surface of the plain paper P, the ink droplet D ′ having increased viscosity is solidified and fixed on the plain paper P. As a result, a higher image density and a sharper image can be formed. In addition, the configuration of the image forming apparatus can be simplified.

  The viscosity of the first solvent S at 25 ° C. is usually 30 mPa · s or less. As a result, the first solvent S can be applied so that the moving speed of the applying member 12 is a high speed of 500 mm / s or more and the unevenness of the thickness of the liquid film is uniform with an average thickness of ± 30% or less. .

  The viscosity of the inkjet ink and the second solvent at 25 ° C. is usually 30 mPa · s or less. Thereby, an inkjet ink can be discharged using an inkjet head.

  For this reason, the diffusion rate at which the second solvent diffuses into the first solvent S is sufficiently larger than the diffusion rate at which the resin and the coloring material diffuse into the first solvent S. As a result, the second solvent diffuses into the first solvent S before the resin and the color material diffuse into the first solvent S in the state of FIG. A region with increased viscosity is formed in the vicinity of the contact surface with the solvent S, and diffusion of the resin and the coloring material into the first solvent S can be suppressed.

The diffusion coefficient in the diffusion between liquids is usually about 1 × 10 ⁻⁹ m ² / s. Assuming that the diffusion coefficient in the diffusion of the second solvent into the first solvent S is also equivalent, the viscosity after the ink droplet D adheres to the first solvent S is calculated based on the diffusion equation. It can be seen that it takes 10 to 100 milliseconds for the concentration of the first solvent S in the ink droplet D ′ having increased to about half the concentration of the first solvent S in the ink droplet D. . Thereby, the viscosity of the ink droplet D can be increased at a high speed, and an image can be formed at a high speed in which the moving speed of the coating member 12 is 500 mm / s or more.

The greater the diffusion speed at which the second solvent diffuses into the first solvent S, the more the resin and coloring material are prevented from diffusing into the first solvent S when the ink droplets D adhere to the first solvent S. can do. That is, the diffusion coefficient in the diffusion of the second solvent into the first solvent S is 1 × 10 ⁻⁹ to 1 × 10 ⁻¹¹ m ² / s under the conditions for actually forming an image in the image forming apparatus. It is preferable that At this time, the diffusion coefficient depends on the temperature and the viscosity, and the viscosity depends on the temperature.

  The region where the first solvent S is applied to the elastic member E is preferably substantially the same as the region where the ink droplet D is adhered. Thereby, the usage-amount of the 1st solvent S can be reduced. Moreover, the transfer of the first solvent S to the plain paper P can be suppressed.

  The shape of the elastic member E is not particularly limited, and examples thereof include a sheet shape and a cylindrical shape.

  In FIG. 2, 1st embodiment of the elastic member E is shown.

  The elastic member E1 has a rough surface on the side to which the first solvent S is applied, and is formed with a recess C1. Thereby, it can suppress that a residual liquid feeling generate | occur | produces in the plain paper P. FIG.

  The ten-point average roughness Ra of the surface of the elastic member E1 on the side to which the first solvent S is applied is usually 0.1 μm to 3.0 μm, and preferably 0.5 μm to 2.0 μm. When the ten-point average roughness Ra of the surface of the elastic member E1 on the side where the first solvent S is applied is less than 0.1 μm, the elastic member E1 is applied to the elastic member E1 when the application member 12 is moved at high speed. The thickness of the first solvent S may partially increase, and a residual liquid feeling may occur on the plain paper P. On the other hand, when the ten-point average roughness Ra of the surface of the elastic member E1 on which the first solvent S is applied exceeds 3.0 μm, the thickness of the first solvent S applied to the elastic member E1 is large. Therefore, a residual liquid feeling may occur on the plain paper P. As a result, when the first solvent S is an aqueous solvent, the plain paper P curls, and when the first solvent S is an oily solvent, an oily feeling is generated on the plain paper P.

  When the first solvent S is applied to the entire surface of the elastic member E1, the first solvent S accumulates in the recess C1, and thus the thickness of the first solvent S can be controlled by the depth of the recess C1.

  The thickness of the first solvent S applied to the elastic member E1 depends on the diameter of the ink droplet D. At this time, the resolution is usually about 300 to 1200 dpi, and the diameter of the ink droplet D is usually about 15 to 40 μm. Further, when the concentration of the first solvent S in the ink droplet D ′ having increased viscosity is about half the concentration of the first solvent S in the ink droplet D, the occurrence of bleeding can be suppressed. Therefore, as a result of the calculation based on the solvent diffusion equation, the theoretical value of the thickness of the first solvent S applied to the elastic member E1 is 1 μm (when the resolution is 1200 dpi) to 3 μm (when the resolution is 300 dpi). Degree.

  On the other hand, the thickness of the first solvent S applied to the elastic member E1 is usually 3 μm or less. When the thickness of the first solvent S applied to the elastic member E1 exceeds 3 μm, a feeling of residual liquid may occur on the plain paper P.

  In FIG. 3, 2nd embodiment of the elastic member E is shown.

  The elastic member E2 has a rough surface on the side to which the first solvent S is applied, and a hemispherical depression C2 is formed. Thereby, it can suppress that a residual liquid feeling generate | occur | produces in the plain paper P. FIG.

  The wavelength of the roughness of the surface of the elastic member E2 on which the first solvent S is applied is usually 0.5 μm to 3.0 μm, and preferably 1.0 μm to 2.0 μm. If the wavelength of the roughness of the surface of the elastic member E1 on which the first solvent S is applied is less than 0.5 μm, ink droplets may be coalesced. On the other hand, if the wavelength of the roughness of the surface of the elastic member E1 on which the first solvent S is applied exceeds 3 μm, blurring may occur.

  FIG. 4 shows a state immediately after the continuous ink droplet D adheres to the first solvent S applied to the elastic member E2.

  When forming a character image or a solid image, the ink droplets D need to be continuously attached to the first solvent S applied to the elastic member E2. At this time, the first solvent S is accumulated in the depression C2, and the ink droplet D attached to the first solvent S slightly enters the depression C2 so as to exclude the first solvent S. For this reason, the ink droplet D becomes difficult to move on the surface of the elastic member E2, and coalescence of the ink droplet D can be suppressed.

  FIG. 5 shows an ink droplet D ′ having an increased viscosity generated on the elastic member E2.

  Since the ink drop D decreases in volume and increases in viscosity along the depression C2, the ink drop D ′ having increased viscosity is somewhat affected by the shape of the depression C2, but the depression C2 is sufficiently small. An image without image omission or image weight can be formed.

  On the other hand, when the elastic member E ′ having no surface roughness is used, the ink droplets D may move and unite on the surface of the elastic member E ′ (see FIG. 6). As a result, the ink droplet D ′ having increased viscosity is split (see FIG. 7), and image omission and image weighting occur.

  In addition, if the viscosity of the ink droplet D increases before the ink droplet D coalesces, the ink droplet D does not coalesce even if the elastic member E ′ having no surface roughness is used.

  On the other hand, when the image forming speed is increased and the interval at which the ink droplets D adhere to the first solvent S is shortened, the ink droplets D may coalesce.

  The ten-point average roughness Ra of the surface of the elastic member E2 on the side to which the first solvent S is applied is usually 0.1 μm to 3.0 μm, and preferably 0.5 μm to 3.0 μm. When the ten-point average roughness Ra of the surface of the elastic member E1 on which the first solvent S is applied is less than 0.1 μm, the thickness of the first solvent S applied to the elastic member E1 is partially The residual liquid feeling may occur on the plain paper P. On the other hand, when the ten-point average roughness Ra of the surface of the elastic member E1 on which the first solvent S is applied exceeds 3.0 μm, the thickness of the first solvent S applied to the elastic member E1 is large. Therefore, a residual liquid feeling may occur on the plain paper P. As a result, when the first solvent S is an aqueous solvent, the plain paper P curls, and when the first solvent S is an oily solvent, an oily feeling is generated on the plain paper P.

  Although it does not specifically limit as a manufacturing method of the elastic member E, The method etc. which grind | polish the elastic member by which the roughness is not provided on the surface using a polishing film are mentioned.

  In FIG. 8, an example of the manufacturing method of the elastic member E is shown.

  First, after forming the binding layer 2 on the film-like support 1, one layer of spherical beads 3 is formed to form a molding die 4. Next, a two-component mixed reaction type resin or rubber material as an elastic precursor EP is formed on the mold 4 (see FIG. 8A). Furthermore, after the precursor EP of the elastic body is cured and then the mold 4 is peeled off, an elastic member E in which a hemispherical depression is formed is obtained (see FIG. 8B).

  The thickness of the binding layer 2 is usually about 3 μm.

  The diameter of the spherical bead 3 is usually 0.5 μm to 6.0 μm.

  In FIG. 9, the other example of the manufacturing method of the elastic member E is shown.

  First, a two-component mixed reaction type resin or rubber material as an elastic precursor and a spherical bead 3 are kneaded and then cured to obtain a sheet-like cured body B (see FIG. 9A). Next, the surface of the cured body B is polished to expose the spherical beads 3, and the elastic member E on which hemispherical protrusions are formed is obtained.

  The plain paper P is not particularly limited, and examples thereof include medium quality paper, high quality paper, and PPC paper.

  Instead of the plain paper P, a transparent film such as a PET film or a polypropylene film, or a metal sheet such as an aluminum sheet or a stainless steel sheet may be used.

  The viscosity of the inkjet ink is usually about 1 to 20 mPa · s.

  The weight average molecular weight of the resin is usually 2000 to 50000. If the weight average molecular weight of the resin is less than 2000, the viscosity may be difficult to increase even if the content of the second solvent in the ink droplet is reduced. If it exceeds 50,000, the viscosity of the inkjet ink is high. May be.

  The resin for the oil-based ink is not particularly limited, and examples thereof include polystyrene, polyester, epoxy resin, acrylic resin, a copolymer containing these in the skeleton, rosin-modified phenol resin, and alkyd resin.

  The second solvent for the oil-based ink is not particularly limited, but dibasic acid esters such as dimethyl succinate, diethyl succinate, dibutyl adipate, isobutyl adipate, dibutyl sebacate, ethyl laurate, isopropyl myristate, Examples include fatty acid esters such as butyl palmitate.

  The coloring material for the oil-based ink may be either an oil-soluble dye or a pigment, but a pigment is preferable because it is difficult to diffuse into the first solvent S.

  The pigment is not particularly limited, but carbon black, phthalocyanine blue, monoazo yellow, disazo yellow, benzimidazole yellow, anthraquinone yellow, polyazo yellow, monoazo red, brilliant carmine 6B, anthraquinone red, dimethylquinacridone, etc. Can be mentioned.

  When a pigment is used as the color material for the oil-based ink, it is preferable to use a pigment dispersant in order to uniformly disperse it in the second solvent.

  The pigment dispersant is not particularly limited, and examples thereof include an alkyl ammonium type polymer dispersant, a block copolymer type polymer dispersant, and a phosphate ester salt dispersant.

  The first solvent S for oil-based ink is not particularly limited as long as it does not dissolve the resin for oil-based ink and can be mixed with the second solvent for oil-based ink, but tridecane, tetradecane, pentadecane. High-boiling paraffinic hydrocarbons such as hexadecane and heptadecane that are liquid at room temperature, high-boiling olefinic hydrocarbons such as pentadecene, hexadecene, and heptadecene, dimethyl silicone oil, and fatty acid ester-modified silicone oil. May be.

  The material constituting the elastic member E for oil-based ink is not particularly limited as long as the wettability with respect to the first solvent S for oil-based ink is good, but silicone rubber, NBR rubber, chloroprene rubber, urethane rubber, fluorine Rubber etc. are mentioned.

  The second solvent for the water-based ink is not particularly limited, and examples thereof include glycols such as glycerin and butylene glycol.

  Although it does not specifically limit as resin for water-based ink, Polyvinyl alcohol, polyvinylpyrrolidone, etc. are mentioned.

  The first solvent S for water-based ink is not particularly limited as long as it does not dissolve the resin for water-based ink and can be mixed with the second solvent for water-based ink, but ethanol, isopropyl alcohol, etc. Alcohols and the like.

  The material constituting the elastic member E for water-based ink is not particularly limited as long as the wettability with respect to the first solvent S for water-based ink is good. Silicone rubber, NBR rubber, chloroprene rubber, urethane rubber, fluorine Rubber etc. are mentioned.

  FIG. 10 shows a first embodiment of the image forming apparatus. 10, the same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  The image forming apparatus 10 includes an intermediate transfer roller 11 having an elastic layer 11b formed on a support 11a, an application member 12 that supplies a first solvent S to the entire surface of the intermediate transfer roller 11, and an image signal. Ink jet head 13 which ejects ink jet ink and causes ink droplet D to adhere to first solvent S applied to intermediate transfer roller 11; and ink droplet D adheres to first solvent S and increases the viscosity It has a pressure roller 14 that transfers ink droplets to plain paper P, and a cleaning pad 15 that removes ink droplets, miscible solvent, paper dust and the like remaining on the intermediate transfer roller 11 to which ink droplets having increased viscosity have been transferred.

  The surface roughness of the elastic layer 11b on the side to which the first solvent S is applied is the same as the surface roughness of the elastic member E1 or the elastic member E2 on the side to which the first solvent S is applied.

  After the ink droplet D adheres to the first solvent S, the concentration of the first solvent S in the ink droplet whose viscosity has increased is about half of the concentration of the first solvent S in the ink droplet D. It takes 10 to 100 milliseconds. Therefore, the time from when the ink droplet D is attached to the first solvent S applied to the intermediate transfer roller 11 to when the ink droplet having increased viscosity is transferred to the plain paper P is usually the ink droplet having increased viscosity. More than the time when the concentration of the first solvent S in the ink droplet D is about half the concentration of the first solvent S in the ink droplet D. The time from when the ink droplet D adheres to the first solvent S applied to the intermediate transfer roller 11 to when the ink droplet with increased viscosity is transferred to the plain paper P is the first in the ink droplet with increased viscosity. If the concentration of the solvent S is less than half of the concentration of the first solvent S in the ink droplet D, bleeding may occur.

  The width of the cleaning pad 15 is substantially the same as the width of the plain paper P.

  The inkjet head 13 may be either a shuttle type head that mechanically scans in the sub-scanning direction or a line type head in which all nozzles are arranged in the width direction of the plain paper P.

  An ink container (not shown) in which inkjet ink is stored is connected to the inkjet head 13 via a tube (not shown) and a pump (not shown).

The amount of the first solvent S applied to the intermediate transfer roller 11 is usually 0.02 to 0.3 mg / cm ² and preferably 0.03 to 0.2 mg / cm ² . If the application amount of the first solvent S to the intermediate transfer roller 11 is less than 0.02 mg / cm ² , the viscosity of the ink droplet D attached to the first solvent S may be difficult to increase, and 0.3 mg When it exceeds / cm ² , a residual liquid feeling may occur on the plain paper P.

  FIG. 11 shows a modification of the image forming apparatus 10.

  The image forming apparatus 20 is the same as the image forming apparatus 10 except that an ink jet head 21 that discharges the first solvent S in accordance with an image signal and applies it to the intermediate transfer roller 11 is used instead of the applying member 12. It is the composition.

  When a monochrome image is formed, the same image signal as that sent to the inkjet head 13 is sent to the inkjet head 21. When a color image is formed, an image signal obtained by converting the color image into a monochrome binary image is sent to the inkjet head 21.

  FIG. 12 shows a second embodiment of the image forming apparatus.

  The image forming apparatus 30 sequentially installs the inkjet heads 13Y, 13M, 13C, and 13B of yellow ink, magenta ink, cyan ink, and black ink instead of the inkjet head 13, and the intermediate transfer belt 11 instead of the intermediate transfer roller 11. The configuration is the same as that of the image forming apparatus 10 except that 31 is used.

  The roughness of the surface of the intermediate transfer belt 31 on which the first solvent S is applied is the same as the roughness of the surface of the elastic member E1 or elastic member E2 on the side where the first solvent S is applied. .

The amount of the first solvent S applied to the intermediate transfer belt 31 is usually 0.02 to 0.3 mg / cm ² and preferably 0.03 to 0.2 mg / cm ² . When the coating amount of the first solvent S on the intermediate transfer belt 31 is less than 0.02 mg / cm ² , the viscosity of the ink droplet D attached to the first solvent S may be difficult to increase, and 0.3 mg When it exceeds / cm ² , a residual liquid feeling may occur on the plain paper P.

  FIG. 13 shows a modification of the image forming apparatus 30.

  The image forming apparatus 40 is the same as the image forming apparatus 40 except that it uses the inkjet head 21 that discharges the first solvent S and applies it to the intermediate transfer roller 11 in accordance with the image signal instead of the application member 12. It is the composition.

  In the present embodiment, “part” means “part by mass”.

(Intermediate transfer roller 0)
An intermediate transfer roller in which an elastic layer made of a silicone rubber KE1353 (manufactured by Shin-Etsu Silicone) with a mirror thickness of 0.3 μm is formed on a cylindrical support made of an aluminum alloy having an outer diameter of 100 mm is used as an intermediate transfer roller Used as roller 0. The intermediate transfer roller 0 had a 10-point average roughness Ra of the surface on which the first solvent S was applied and a surface roughness wavelength of 0.05 μm.

(Preparation of intermediate transfer roller 1-1)
The intermediate transfer roller 0 was polished with a color wrap film sheet # 240 (manufactured by 3M) to obtain an intermediate transfer roller 1-1. The intermediate transfer roller 1-1 had a 10-point average roughness Ra of 0.7 μm on the surface on which the first solvent S was applied.

(Preparation of intermediate transfer roller 1-2)
The intermediate transfer roller 0 was polished with a color wrap film sheet # 2400 (manufactured by 3M) to obtain an intermediate transfer roller 1-2. The intermediate transfer roller 1-2 had a 10-point average roughness Ra of 1.2 μm on the surface on which the first solvent S was applied.

(Preparation of intermediate transfer roller 1-3)
The intermediate transfer roller 0 was polished with a color wrap film sheet # 800 (manufactured by 3M) to obtain an intermediate transfer roller 1-3. The intermediate transfer roller 1-3 had a ten-point average roughness Ra of 2.8 μm on the surface on which the first solvent S was applied.

(Preparation of intermediate transfer roller 1-4)
The intermediate transfer roller 0 was polished with a color wrap film sheet # 2000 (manufactured by 3M) to obtain an intermediate transfer roller 1-4. The intermediate transfer roller 1-4 had a 10-point average roughness Ra of 5.3 μm on the surface on which the first solvent S was applied.

(Preparation of intermediate transfer roller 1-5)
The intermediate transfer roller 0 was polished with a color wrap film sheet # 3000 (manufactured by 3M) to obtain an intermediate transfer roller 1-5. The intermediate transfer roller 1-5 had a 10-point average roughness Ra of 13.4 μm on the surface on which the first solvent S was applied.

(Example 1-1)
While stirring using a stirrer, 9 parts of low molecular weight polyester Byron 220 (manufactured by Toyobo Co., Ltd.) was dissolved in 82 parts of vinylizer 40 (diisobutyl adipate) (manufactured by Kao Corporation), and then the pigment dispersant DISPERBYK-2155 ( 2 parts (by Big Chemie Japan) were dissolved. Next, the obtained solution, 4 parts of carbon black # 2350 (manufactured by Mitsubishi Chemical Corporation) and zirconia beads having a diameter of 0.3 mm were placed in a container, and then dispersed for 1 hour while being vibrated and stirred using a ball mill. Furthermore, it filtered using the filter with a hole diameter of 0.45 micrometer, and obtained the inkjet ink.

  An image was formed using the image forming apparatus 10.

As an inkjet head, a pulse injector PIJ-15NSET (manufactured by Cluster Technology) was used. Moreover, Exepar iPM (isopropyl myristate) (made by Kao Corporation) was used as the first solvent S, and sponge (made by Toyo Polymer Co., Ltd.) was used as the sponge 12b. Further, the intermediate transfer roller 1-1 was used as the intermediate transfer roller 11, and A4 PPC paper Myper (manufactured by Ricoh) was used as the plain paper P. Further, the coating member 12 and the inkjet head 13 are set so that the time from the application of the first solvent S to the intermediate transfer roller 11 until the ink droplets D adhere to the first solvent S is 0.5 seconds. Arranged. Furthermore, the inkjet head 13 and the pressure roller 14 were arranged so that the time from when the ink droplet D was attached to the solvent S to when the ink droplet with increased viscosity was transferred was 0.5 seconds. Further, after applying the first solvent S so that the coating amount on the entire surface of the intermediate transfer roller 11 was 0.13 mg / cm ² , about 8 pL of the ink droplet D was adhered to the first solvent S. The linear speed of the intermediate transfer roller 11 was set to 150 mm / s or 500 mm / s.

(Example 1-2)
An image was formed in the same manner as in Example 1-1 except that the intermediate transfer roller 1-2 was used instead of the intermediate transfer roller 1-1.

(Example 1-3)
An image was formed in the same manner as in Example 1-1 except that the intermediate transfer roller 1-3 was used instead of the intermediate transfer roller 1-1.

(Comparative Example 1-1)
An image was formed in the same manner as in Example 1-1 except that the intermediate transfer roller 0 was used instead of the intermediate transfer roller 1-1.

(Comparative Example 1-2)
An image was formed in the same manner as in Example 1-1 except that the intermediate transfer roller 1-4 was used instead of the intermediate transfer roller 1-1.

(Comparative Example 1-3)
An image was formed in the same manner as in Example 1-1 except that the intermediate transfer roller 1-5 was used instead of the intermediate transfer roller 1-1.

  Next, bleeding and oil feeling were evaluated.

(Bleed)
The bleeding of the image formed on the plain paper P was evaluated using an optical microscope. In addition, the case where there was no blur was evaluated as ◯, the case where there was a slight blur as Δ, and the case where there was a significant blur as X.

(Oil feeling)
The oily feeling of plain paper P on which an image was formed was evaluated. In addition, when there is no sense of incongruity even when the plain paper P is touched, there is no sense of incongruity even when the plain paper P is touched, but when the oil remains on the plain paper P visually, the oil is felt by touching the plain paper P. The case where there was a feeling was judged as x.

  Table 1 shows the evaluation results of image blur and plain paper oil feeling.

From Table 1, it can be seen that Examples 1-1 to 1-3 can suppress the occurrence of bleeding and oily feeling when the linear transfer roller 11 has a linear velocity of 150 mm / s and 500 mm / s.

  On the other hand, in Comparative Example 1-1, the 10-point average roughness Ra of the surface of the intermediate transfer roller 0 on the side where the first solvent S is applied is 0.05 μm. An oily feeling occurs when the speed is set to 500 mm / s.

  In Comparative Examples 1-2 and 1-3, the 10-point average roughness Ra of the surface of the intermediate transfer rollers 1-4 and 1-5 to which the first solvent S is applied is 5.3 μm and 13.4 μm. Therefore, an oily feeling is generated when the linear speed of the intermediate transfer roller 11 is 150 mm / s or 500 mm / s.

(Preparation of intermediate transfer roller 2-1)
An adhesive is applied to the inner surface of a semi-cylindrical support made of aluminum alloy having a thickness of 3 mm, an outer diameter of 108 mm, and an inner diameter of 102 mm to form a binding layer having a thickness of 3 μm. One layer of spherical beads Tospearl 120 (Momentive Performance Materials Co., Ltd.) having a diameter of 2.0 μm was formed on the wearing layer to obtain a molding die. Next, after combining the two molds into a cylindrical mold, an aluminum alloy columnar support having an outer diameter of 100 mm was placed inside the cylindrical mold. Further, a room temperature curing type silicone rubber KE1353 (manufactured by Shin-Etsu Silicone Co., Ltd.) was poured between the cylindrical mold and the cylindrical support and then cured. Next, the semi-cylindrical mold was peeled off to obtain an intermediate transfer roller 2-1 having a hemispherical depression. The intermediate transfer roller 2-1 has a ten-point average roughness Ra of the surface on which the first solvent S is applied having a thickness of 1.0 μm, and the wavelength of the roughness on the surface on which the first solvent S is applied. It was 2.0 μm.

  FIG. 14 shows an optical micrograph of the surface of the intermediate transfer roller 2-1 on the side where the first solvent S is applied.

(Preparation of intermediate transfer roller 2-2)
Instead of using Tospearl 120 (made by Momentive Performance Materials) with spherical beads with a diameter of 2.0 μm, Tospearl 145 (made by Momentive Performance Materials) with spherical beads with a diameter of 4.5 μm was used. Obtained an intermediate transfer roller 2-2 in the same manner as the intermediate transfer roller 2-1. In the intermediate transfer roller 2-2, the ten-point average roughness Ra of the surface on which the first solvent S is applied is 2.0 μm, and the wavelength of the roughness on the surface on which the first solvent S is applied is It was 4.5 μm.

  FIG. 15 shows an optical micrograph of the surface of the intermediate transfer roller 2-2 on which the first solvent S is applied.

(Preparation of intermediate transfer roller 2-3)
Intermediate transfer roller 2 except that instead of Tospearl 120 (made by Momentive Performance Materials) having a spherical bead of 2.0 μm in diameter, Sicastar 1 μm (made by McModod) having a spherical bead having a diameter of 1.0 μm was used. In the same manner as -1, an intermediate transfer roller 2-3 was obtained. The intermediate transfer roller 2-3 has a 10-point average roughness Ra of 0.5 μm on the surface to which the first solvent S is applied and a wavelength of roughness on the surface on which the first solvent S is applied. It was 1.0 μm.

(Example 2-1)
Instead of the intermediate transfer roller 1-1, the intermediate transfer roller 2-1 is used, and about 8 pL of ink droplets D are continuously applied to the intermediate transfer roller 11 under an ink dot pitch of 30 μm. Except that the intermediate transfer roller 11 has a linear velocity of 150 mm / s and the coated paper OK Super Art (manufactured by Oji Paper Co., Ltd.) was used as the plain paper P, in the same manner as in Example 1-1. Formed.

  FIG. 16 shows an optical micrograph of the image. A white line indicates an ideal image pattern.

(Example 2-2)
An image was formed in the same manner as in Example 2-1, except that the intermediate transfer roller 2-2 was used instead of the intermediate transfer roller 2-1.

  FIG. 17 shows an optical micrograph of the image. A white line indicates an ideal image pattern.

(Example 2-3)
An image was formed in the same manner as in Example 2-1, except that the intermediate transfer roller 2-3 was used instead of the intermediate transfer roller 2-1.

(Comparative Example 2-1)
An image was formed in the same manner as in Example 2-1, except that the intermediate transfer roller 0 was used instead of the intermediate transfer roller 2-1.

  FIG. 18 shows an optical micrograph of the image. A white line indicates an ideal image pattern.

  Next, bleeding, oil feeling, coalescence of ink droplets and blurring were evaluated.

(Ink droplet combination)
The coalescence of the ink droplets D was evaluated from the image formed on the plain paper P using an optical microscope. Note that the case where the ink droplets D were not coalesced was evaluated as ◯, the case where some of the ink droplets D were coalesced, and the case where the ink droplets D were significantly coalesced as x.

(Smear)
The blur of the image formed on the plain paper P was evaluated using an optical microscope. In addition, the case where there was no fading was judged as ◯, the case where there was faint in part, Δ, and the case where there was faint as a whole as x.

  Table 2 shows the evaluation results of bleeding, oil feeling, coalescence of ink droplets and blur.

From Table 2, it can be seen that Examples 2-1 and 2-3 can suppress the occurrence of bleeding, oil feeling, coalescence of ink droplets and blurring.

  In Example 2-2, since the wavelength of the roughness of the surface of the intermediate transfer roller 2-2 on which the first solvent S is applied is 4.5 μm, blurring occurs.

  In Comparative Example 2-1, since the wavelength of the roughness of the surface of the intermediate transfer roller 0 on the side where the first solvent S is applied is 0.05 μm, ink coalescence occurs.

C1, C2 Dimple D Ink Drop D 'Ink Drop with Increased Viscosity E, E1, E2 Elastic Member P Plain Paper S First Solvent S' Mixed Solvent 10, 20, 30, 40 Image Forming Apparatus 11 Intermediate Transfer Roller 11a Support Body 11b Elastic layer 12 Application member 12a Support plate 12b Sponge 13, 21 Inkjet head 14 Pressure roller 15 Cleaning pad 31 Intermediate transfer belt

JP 2011-143705 A

Claims (8)

Applying a first solvent to the intermediate transfer member;
Discharging ink jet ink to adhere to the first solvent applied to the intermediate transfer member;
Transferring the ink-jet ink attached to the first solvent to a recording medium;
The inkjet ink includes a second solvent, a resin and a colorant dissolved in the second solvent,
The first solvent can deposit the resin when the inkjet ink is dropped.
The second solvent is miscible with the first solvent;
The image forming method, wherein the intermediate transfer member has a rough surface on the side to which the first solvent is applied.   2. The image forming method according to claim 1, wherein the intermediate transfer member has a 10-point average roughness Ra of 0.5 μm or more and 3.0 μm or less on the surface on which the first solvent is applied. .   The image forming method according to claim 2, wherein the intermediate transfer member has a surface roughness wavelength of 1.0 μm or more and 2.0 μm or less to which the first solvent is applied.   4. The image forming method according to claim 1, wherein a region to which the first solvent is applied is substantially the same as a region to which the inkjet ink is attached. An intermediate transfer member;
Application means for applying a first solvent to the intermediate transfer member;
An ejection unit that ejects inkjet ink and adheres to the first solvent applied to the intermediate transfer member;
A transfer means for transferring the inkjet ink attached to the first solvent to a recording medium;
The inkjet ink includes a second solvent, a resin and a colorant dissolved in the second solvent,
The first solvent can deposit the resin when the inkjet ink is dropped.
The second solvent is miscible with the first solvent;
The image forming apparatus, wherein the intermediate transfer member has a rough surface on the side to which the first solvent is applied.   6. The image forming apparatus according to claim 5, wherein the intermediate transfer member has a ten-point average roughness Ra of 0.5 μm or more and 3.0 μm or less on the surface on which the first solvent is applied. .   The image forming apparatus according to claim 6, wherein the intermediate transfer member has a surface roughness wavelength of 1.0 μm or more and 2.0 μm or less to which the first solvent is applied.   8. The image forming apparatus according to claim 5, wherein a region to which the first solvent is applied is substantially the same as a region to which the inkjet ink is attached.