JP2013018164A - Inkjet recording method, and recorded matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording method capable of recording an image superior in color developability.SOLUTION: This inkjet recording method includes: a first image recording step of recording an image by ejecting a droplet of an ink composition containing at least a sparingly water-soluble alkanediol from a nozzle and causing the droplet to adhere on one surface of the first recording medium; a lamination step of bringing the one surface of the first recording medium into contact with the other surface of the second recording medium to laminate them; and a second image recording step of recording an image by ejecting a droplet of the ink composition and causing the droplet to adhere on the other surface of the second recording medium, in this order. The method further includes, before the second image recording step, at least one of a coating step of coating the image recorded on the one surface of the first recording medium with a coating agent and a removal step of removing a portion of components included in the image recorded on the one surface of the first recording medium.

Description

  The present invention relates to an ink jet recording method and a recorded matter obtained thereby.

  Conventionally, an image recording method for recording images on both sides of a recording medium using various image recording apparatuses is known. For example, in Patent Document 1, after an image is recorded on one surface (front surface) of a recording medium, the recording medium is inverted while the recording medium is held inside the image recording apparatus, and the other surface (back surface) is recorded. ) Describes a method of recording an image.

  However, when performing double-sided printing of a large number of recording media as in the image recording method described in Patent Document 1 described above, if a method of performing double-sided printing for each recording medium is employed, all the recording media are used. On the other hand, it is necessary to spend a lot of time until the double-sided printing is completed. For this reason, there is a need for a method capable of performing duplex printing at a higher speed, particularly when images need to be duplex printed on a large number of sheets, such as in the industrial field (for example, advertising printing field).

  By the way, with the recent technological advancement of the ink jet recording system, the ink jet recording system has come to be used in fields that have not been used so far. For example, in order to create a printed material (for example, a flyer) distributed for advertisements, offset printing is used as a printing method, and a low-ink-absorbing recording medium is often used as a recording medium. It is not used much. One reason for this is that when general inkjet water-based ink is used for printing on a low-absorbing recording medium, ink repelling, image bleeding, shading unevenness, etc. occur, resulting in good image recording. Was difficult. Therefore, in order to solve such a problem, Patent Document 2 and Patent Document 3 describe that an ink composition contains a hardly water-soluble alkanediol or the like.

JP 2008-170695 A JP 2009-209338 A JP 2009-297924 A

  As a method for performing double-sided printing of a large number of recording media at high speed, for example, after images are continuously recorded on one side of a plurality of recording media, the recording medium is continuously recorded on the other side of the plurality of recording media. And a method of recording an image.

  In such a case, when an image is recorded on a low-ink-absorbing recording medium using the ink compositions described in Patent Document 2 and Patent Document 3 described above, the image is recorded on either surface of the recording medium. In some cases, the color developability of the image was lowered. Specifically, after recording an image on one side of the first recording medium and the second recording medium, when the first recording medium and the second recording medium are stacked, one side of the first recording medium And the other surface of the second recording medium come into contact with each other. Thereby, the component contained in the image of the first recording medium may adhere to the other surface of the second recording medium. Thereafter, when an image is recorded on the other surface of the second recording medium, the image recorded on one surface of the first recording medium out of the images recorded on the other surface of the second recording medium is contacted. In some cases, the color developability of the image of the portion that had been deteriorated was lowered.

  Some embodiments according to the present invention provide an ink jet recording method capable of recording an image having excellent color developability by solving at least a part of the above problems.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the inkjet recording method according to the present invention is:
An inkjet recording method for recording an image on the surface of a plurality of non-absorbing or low-absorbing recording media,
A droplet of an ink composition containing a hardly water-soluble alkanediol, a water-soluble alkanediol, a coloring material, and water is ejected from a nozzle, and the droplet is applied to one side of the first recording medium. A first image recording step of recording an image attached to the
A laminating step of laminating the first recording medium and the second recording medium by bringing one surface of the first recording medium into contact with the other surface of the second recording medium;
A second image recording step of recording an image by discharging droplets of the ink composition from the nozzle and attaching the droplets to the other surface of the second recording medium;
In this order,
Before the second image recording step,
An image recorded on one side of the first recording medium is coated with a coating agent that does not substantially contain a slightly water-soluble alkanediol, and recorded on one side of the first recording medium It includes at least one of removal steps for removing a part of the components included in the image.

  According to the aspect described in Application Example 1, an image having excellent color developability can be obtained.

[Application Example 2]
In application example 1,
By the laminating step, recording is performed on the other surface of the second recording medium on the first surface of the first recording medium and the first region in contact with the image recorded on the one surface of the first recording medium. A second region that does not contact the rendered image,
In the second image recording step, when an image is recorded by attaching the same amount of the ink composition to the first area and the second area, the OD values of the first area and the second area are The difference can be less than 0.05.

[Application Example 3]
In application example 1 or application example 2,
A third image recording step of recording an image by discharging droplets of the ink composition from the nozzle and attaching the droplets to one surface of the second recording medium;
And a fourth image recording step of recording an image by ejecting droplets of the ink composition from the nozzle and attaching the droplets to the other surface of the first recording medium.

[Application Example 4]
In any one of Application Examples 1 to 3,
After continuously recording images on one side of the plurality of non-ink-absorbing or low-absorbing recording media, continuously on the other side of the plurality of non-absorbing or low-absorbing recording media Images can be recorded.

[Application Example 5]
In any one of Application Examples 1 to 4,
The coating agent contains a resin and can be substantially free of a coloring material and a slightly water-soluble alkanediol.

[Application Example 6]
In application example 5,
The resin contained in the coating agent may be at least one selected from a sulfonate resin, a polyolefin resin, and a modified polyolefin resin.

[Application Example 7]
In any one of Application Examples 1 to 6,
The removal in the removing step can be performed by drying an image recorded on one surface of the first recording medium.

[Application Example 8]
One aspect of the recorded matter according to the present invention is:
It is recorded by the ink jet recording method described in any one of Application Examples 1 to 7.

FIG. 2 is a perspective view schematically illustrating a configuration of a printer according to the embodiment of the invention.

  Hereinafter, preferred embodiments of the present invention will be described. The embodiment described below describes an example of the present invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

1. Inkjet recording method According to an embodiment of the present invention, an inkjet recording method records an image continuously on one surface of a plurality of ink non-absorbing or low-absorbing recording media, and then the plurality of ink non-absorbing. Or, it is an ink jet recording method in which images are continuously recorded on the other surface of the low-absorbency recording medium.

  The ink jet recording method according to the present embodiment can be performed using, for example, an ink jet recording apparatus.

1.1. Inkjet Recording Apparatus First, an inkjet recording apparatus used in the inkjet recording method according to the present embodiment will be described.

  The ink jet recording apparatus according to this embodiment includes a nozzle that discharges a droplet of the ink composition. The ink jet recording apparatus according to this embodiment will be described below with reference to FIG. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size. In the present embodiment, an inkjet printer (hereinafter simply referred to as “printer”) is illustrated as an inkjet recording apparatus.

  FIG. 1 is a perspective view illustrating a configuration of a printer 1 according to the present embodiment. A printer 1 shown in FIG. 1 is a serial printer. A serial printer is a printer in which a head is mounted on a carriage that moves in a predetermined direction, and droplets are ejected onto a recording medium by moving the head as the carriage moves.

  1 illustrates a serial printer, the present invention is not limited to this, and the inkjet recording apparatus according to the present invention may be, for example, a line printer. A line printer refers to a printer in which a head is formed wider than the width of a recording medium and droplets are ejected onto the recording medium without moving the head.

  As shown in FIG. 1, the printer 1 includes a carriage 4 on which a head 2 is mounted and an ink cartridge 3 is detachably mounted, a platen 5 that is disposed below the head 2 and transports a recording medium P, and a carriage. 4 includes a carriage moving mechanism 7 that moves the recording medium P in the medium width direction of the recording medium P, and a medium feeding mechanism 8 that conveys the recording medium P in the medium feeding direction. The printer 1 also has a control device CONT that controls the operation of the entire printer 1. The medium width direction is the main scanning direction (head scanning direction). The medium feeding direction is a sub-scanning direction (a direction orthogonal to the main scanning direction).

  The ink cartridge 3 according to this embodiment includes four independent cartridges. These ink cartridges are filled with an ink composition to be described later. In the example of FIG. 1, the number of cartridges is four. However, the number of cartridges is not limited to this, and a desired number of cartridges can be mounted. The ink cartridge 3 is not limited to the one mounted on the carriage 4 as in the present embodiment. Instead, for example, the ink cartridge 3 is mounted on the housing side of the printer 1 and supplied to the head 2 via the ink supply tube. It may be a thing.

  The carriage 4 is attached in a state of being supported by a guide rod 9 which is a support member installed in the main scanning direction. The carriage 4 is moved in the main scanning direction along the guide rod 9 by the carriage moving mechanism 7. In the example of FIG. 1, the carriage 4 moves in the main scanning direction. However, the present invention is not limited to this, and the carriage 4 may move in the sub scanning direction in addition to the movement in the main scanning direction. .

  The head 2 includes a nozzle (not shown). The head 2 deposits the ink composition on the recording medium P by discharging the ink composition from a nozzle (not shown) into droplets having a minute particle diameter. The head 2 is not particularly limited as long as it has the above function, and any ink jet recording method may be used. As the ink jet recording system of the head 2, for example, a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, and droplet ink is continuously ejected from the nozzle to deflect the ink droplet. A method in which a printing information signal is applied to a polarizing electrode while flying between the electrodes and recording is performed, or a method in which ink droplets are ejected in accordance with the printing information signal without being deflected (electrostatic suction method). Pressure is applied to the liquid, and the nozzle is mechanically vibrated by a quartz oscillator or the like to forcibly eject ink droplets. The pressure and print information signal are simultaneously applied to the ink using a piezoelectric element. Examples include a method for ejecting and recording droplets (piezo method), a method for heating and foaming ink with a microelectrode in accordance with a print information signal, and a method for ejecting and recording ink droplets (thermal jet method). That.

  The linear encoder 10 detects the position of the carriage 4 in the main scanning direction with a signal. This detected signal is transmitted to the control device CONT as position information. The control device CONT recognizes the scanning position of the head 2 based on the position information from the linear encoder 10, and controls the recording operation (discharge operation) by the head 2. Further, the control device CONT is configured to be able to variably control the moving speed of the carriage 4.

1.2. Ink Composition Next, the ink composition used in the ink jet recording method according to this embodiment will be described.

  The ink composition used in the ink jet recording method according to the present embodiment contains a slightly water-soluble alkanediol, a water-soluble alkanediol, a coloring material, and water. Hereinafter, each component will be described.

  In the present invention, the alkanediol and the alkylene glycol may have either a linear or branched structure.

  In the present invention, water-soluble means that the solubility in water (the amount of solute with respect to 100 g of water) is 10 g or more, and the poorly water-soluble means the solubility in water (the amount of solute with respect to 100 g of water). Means less than 1 g.

1.2.1. Slightly water-soluble alkanediol The ink composition according to this embodiment contains a sparingly water-soluble alkanediol. One of the functions of the poorly water-soluble alkanediol is to significantly reduce the interfacial tension between the ink composition and the ink-absorbing recording medium. As a result, the ink composition according to this embodiment containing a hardly water-soluble alkanediol can be used for conventional inkjets that do not contain a hardly water-soluble alkanediol in recording an image on a recording medium having low ink absorption. Compared with this water-based ink, it is possible to extremely effectively suppress the occurrence of ink splashing, bleeding, density unevenness and the like.

  The slightly water-soluble alkanediol is preferably an alkanediol having 7 or more carbon atoms. For example, 1,2-heptanediol, 1,2-octanediol, 5-methyl-1,2-hexanediol, 4-methyl- 1,2-hexanediol, 4,4-dimethyl-1,2-pentanediol and the like. Among these, 1,2-octanediol can be used more preferably.

  The content of the slightly water-soluble alkanediol is preferably 1% by mass or more and 5% by mass or less, and more preferably 1.5% by mass or more and 4% by mass or less with respect to the total mass of the ink composition. preferable. When the content of the slightly water-soluble alkanediol is within the above range, a good image with little ink repelling or the like can be formed on a recording medium with low ink absorption. In addition to this, when it is within the above range, it is easy to make the viscosity of the ink composition within a range that can be satisfactorily discharged from the nozzles of the ink jet recording apparatus, or an oil layer in the ink composition (a poorly water-soluble alkane). Diol) separation can be effectively suppressed.

1.2.2. Water-soluble alkanediol The ink composition according to this embodiment contains a water-soluble alkanediol. One of the functions of the water-soluble alkanediol is to reduce bleeding of the recorded image and to stably disperse or dissolve the poorly water-soluble alkanediol in the ink composition. It is done.

  Water-soluble alkanediols are alkanediols having hydroxyl groups at both ends of the alkyl group main chain (both end type alkanediols) or alkanediols having hydroxyl groups at one end of the alkyl group main chain (one end type alkanes). Diol). Among these, the water-soluble alkanediol preferably has 6 or less carbon atoms, and more preferably has 3 to 6 carbon atoms. Specific examples of the water-soluble alkanediol include 1,2-hexanediol, 1,2-pentanediol, 1,2-butanediol, 4-methyl-1,2-pentanediol, and 3,3-dimethyl. -1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol and the like. Among these, 1,2-hexanediol is preferable from the viewpoint of odor during printing.

  The content of the water-soluble alkanediol is preferably 0.5% by mass or more and 6% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less with respect to the total mass of the ink composition. More preferred. When the content of the water-soluble alkanediol is within the above range, the slightly water-soluble alkanediol can be well dispersed or dissolved in the ink composition.

  In the ink composition, the content ratio of the slightly water-soluble alkanediol to the water-soluble alkanediol (content of the poorly water-soluble alkanediol / content of the water-soluble alkanediol) is 0.3. It is preferably 6 or more and more preferably 1 or more and 6 or less. When the content ratio is within the above range, the slightly water-soluble alkanediol can be stably dissolved or dispersed in the ink composition.

1.2.3. Colorant The ink composition according to this embodiment contains a colorant. Pigments and dyes can be used for the color material. Among these, a pigment can be preferably used from the viewpoint of excellent light resistance. The content of the color material is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, with respect to the total mass of the ink composition.

  Although it does not restrict | limit especially as a pigment which can be used in this embodiment, An inorganic pigment and an organic pigment are mentioned. As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used. Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone. Polycyclic pigments such as pigments, dye chelates (for example, basic dye type chelates, acidic dye type chelates), dyeing lakes (basic dye type lakes, acid dye type lakes), nitro pigments, nitroso pigments, aniline black, A daylight fluorescent pigment is mentioned. The said pigment may be used individually by 1 type, and may use 2 or more types together.

  More specifically, examples of the inorganic pigment used for black include the following carbon blacks, for example, No. manufactured by Mitsubishi Chemical. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; Cabot Regal 400R, Regal 330R, Regal 660L, Monal 660R 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Color Black FW2, Clk Black FW2C, Decksa's Color Black FW2 FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, and Special Black 5S.

  Examples of yellow organic pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, 180, 185, 213, pigments described in [Chemical Formula 1] of International Publication No. 2011/027842, and the like can be used alone or in combination of two or more. Among these, C.I. I. Pigment Yellow 74, 128, 129, 155, 180, 185, 213, and one or more selected from the group consisting of pigments described in [Chemical Formula 1] of International Publication No. 2011/027842 can be preferably used. .

  Examples of magenta organic pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, 254, 264 or C.I. I. And CI Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50 and the like, and one or more of them can be used. Among these, C.I. I. Pigment red 122, 202, 209, and C.I. I. One or more selected from the group consisting of CI Pigment Violet 19 can be preferably used, and it is more preferable to use these solid solutions.

  Examples of cyan organic pigments include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15:34, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat blue 4, 60, etc. are mentioned, and these can be used alone or in combination. Among these, C.I. I. Pigment Blue 15: 3, 15: 4 can be preferably used.

  Examples of organic pigments other than magenta, cyan and yellow include C.I. I. Pigment green 7, 10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, and the like.

  Various methods can be applied to the above pigment in order to make it more stably dispersed and held in the ink. As the method, for example, a dispersion method using a water-soluble resin or a water-insoluble resin, a dispersion method using a surfactant, a hydrophilic functional group is introduced into the pigment particle surface chemically and physically, and the dispersion is performed. And / or a method for making it soluble. Any of the above-described methods can be used for the ink composition in the present embodiment, and the methods can be used in a combined form as necessary. In particular, in a method in which a pigment is dispersed in an ink composition by a water-soluble resin, when the ink adheres to the recording medium, the adhesion between the recording medium and the ink composition and / or the solidified material in the ink composition is achieved. It may be possible to improve the properties. In addition, the method in which a hydrophilic functional group is chemically and physically introduced on the surface of pigment particles to disperse the pigment in the ink composition improves the dispersion stability of the pigment and improves the storage stability of the ink composition. This is preferable.

  Water-soluble resins that can be used for pigment dispersion include polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylic acid ester copolymers, acrylic acid-acrylic acid ester copolymers. Polymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene -Acrylic acid-acrylic acid ester copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, vinyl acetate-maleic acid Acid ester copolymer, vinyl acetate-crotonic acid copolymer , Vinyl acetate-acrylic acid copolymer, and salts thereof. Among these, a copolymer of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and a polymer comprising a monomer having both a hydrophobic functional group and a hydrophilic functional group are particularly preferable. As the form of the copolymer, any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer can be used.

  Examples of the salt include bases such as ammonia, ethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolamine, triethanolamine, tri-iso-propanolamine, aminomethylpropanol, and morpholine. And a salt with a functional compound. The addition amount of these basic compounds is not particularly limited as long as it is at least the neutralization equivalent of the water-soluble resin.

  The molecular weight of the water-soluble resin that can be used for dispersing the pigment is preferably in the range of 1,000 to 100,000, and more preferably in the range of 2,000 to 30,000 as the weight average molecular weight. When the molecular weight is in the above range, stable dispersion of the coloring material in water is obtained, and viscosity control when applied to the ink composition is easy. Moreover, it is preferable that it is the range of 50-300 as an acid value, and it is more preferable that it is the range of 70-250. When the acid value is within this range, the dispersibility of pigment particles in water can be stably secured, and the water resistance of an image recorded with an ink composition using the pigment particles may be improved.

  Commercially available products can also be used as the water-soluble resin that can be used for dispersing the pigment described above. Specifically, Joncryl 67 (weight average molecular weight: 12,500, acid value: 213), Joncryl 678 (weight average molecular weight: 8,500, acid value: 215), Joncryl 586 (weight average molecular weight: 4,600) , Acid value: 108), joncryl 611 (weight average molecular weight: 8,100, acid value: 53), joncryl 680 (weight average molecular weight: 4,900, acid value: 215), joncryl 682 (weight average molecular weight) : 1,700, acid value: 238), joncryl 683 (weight average molecular weight: 8,000, acid value: 160), joncryl 690 (weight average molecular weight: 16,500, acid value: 240) , Manufactured by BASF Japan Ltd.).

As a method of introducing a hydrophilic functional group into the pigment particle surface chemically and physically so that the pigment can be dispersed and / or dissolved, the hydrophilic functional group can be -OM, -COOM, -CO-, -SO as a hydrophilic functional group in the pigment. ₃ M, —SO ₂ NH ₂ , —RSO ₂ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NHCOR, —NH ₃ , —NR ₃ (wherein M is a hydrogen atom, an alkali Represents a metal, ammonium, or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group. The method to introduce is mentioned. These functional groups are physically and / or chemically introduced by grafting directly to the pigment particle surface and / or via other groups. Examples of the polyvalent group include an alkylene group having 1 to 12 carbon atoms, a phenylene group which may have a substituent, or a naphthylene group which may have a substituent.

Further, as the surface treatment method, the -SO 3 _M and / or -RSO 2 _M (M in the pigment particle surface by treatment agent containing sulfur a counter ion, a hydrogen ion, an alkali metal ion, an ammonium ion Or an organic ammonium ion)) that has been surface-treated so as to chemically bond, that is, the pigment does not have an active proton, has no reactivity with sulfonic acid, and the pigment is insoluble or hardly soluble. In the solvent, the pigment is dispersed, and then surface treatment is performed so that -SO ₃ M and / or -RSO ₂ M are chemically bonded to the particle surface by amidosulfuric acid or a complex of sulfur trioxide and tertiary amine. More preferably, it can be dispersed and / or dissolved in water.

  The functional group grafted on one pigment particle may be single or plural kinds. The type and degree of the functional group to be grafted may be appropriately determined in consideration of the dispersion stability in the ink, the color density, the drying property on the front surface of the inkjet head, and the like.

  The method for dispersing the pigment in water includes: pigment, water, and water-soluble resin for water-soluble resin; pigment, water, and surfactant for surfactant; and pigment and water for surface-treated pigment; Add water-soluble organic solvent / neutralizer, etc. as necessary to ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc. Can be carried out with a disperser. In this case, the average particle diameter of the pigment is dispersed until the average particle diameter is in the range of 20 nm to 500 nm, more preferably in the range of 50 nm to 200 nm, thereby ensuring dispersion stability of the pigment in water. This is preferable. Further, by using a pigment having an average particle diameter of 250 nm or less, clogging can be suppressed, and more sufficient ejection stability can be realized. In the present application, the average particle diameter is a volume-based average particle diameter unless otherwise specified.

1.2.4. Water The ink composition according to the present embodiment contains water. Water is a main medium of the ink composition and is a component that evaporates and scatters. The water is preferably water from which ionic impurities such as pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water or ultrapure water are removed as much as possible. In addition, it is preferable to use water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide because generation of mold and bacteria can be prevented when the ink composition is stored for a long time. The water contained in the ink composition according to this embodiment is preferably 50% by mass or more based on the total mass of the ink composition.

1.2.5. Other Components The ink composition according to this embodiment may further contain (poly) oxyalkylene glycol, resins, a surfactant, and other components.

(1) (Poly) oxyalkylene glycol (Poly) oxyalkylene glycol is a viewpoint that it is possible to further reduce bleeding and shading unevenness of an image recorded on a low-absorbing recording medium and to reduce ink nozzle clogging. Can be used.

  The (poly) oxyalkylene glycol is preferably a water-miscible oligomer obtained by addition polymerization of ethylene oxide and / or propylene oxide. Specifically, the (poly) oxyalkylene glycol is preferably one or more selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol. More preferably, it is one or more selected from the group consisting of triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol. Among these, (poly) oxyalkylene glycol is preferably water-miscible (poly) propylene glycol. The (poly) propylene glycol is not particularly limited, but dipropylene glycol is more preferable.

  When (poly) oxyalkylene glycol is contained, the content thereof is preferably 2% by mass or more and 18% by mass or less, and preferably 6% by mass or more and 18% by mass or less with respect to the total mass of the ink composition. More preferably. When the content of the (poly) oxyalkylene glycol is within the above range, the slightly water-soluble alkanediol can be kept in a mixed state without being separated when the ink droplet is dried. Furthermore, the initial viscosity of the ink does not become too high, and separation of the oil layer can be reduced in a normal ink storage state.

(2) Resins The ink composition according to this embodiment may contain resins. Examples of the resins include, in addition to the water-soluble resins that can be used for dispersing the pigments described above, for example, (i) polyolefin resins, (ii) modified polyolefin resins, (iii) sulfonic acid ester resins, (iv) fluorene resins, and the like. Can be mentioned. These resins may be used alone or in combination of two or more.

(I) Polyolefin resin The polyolefin resin can reduce scratches on the surface of the recording medium and can improve the fixability of the ink.

  As the polyolefin resin, it is preferable to use a particulate resin. The average particle diameter of the particulate polyolefin resin is preferably larger than the film thickness of the image recorded on the recording medium, specifically, more preferably 10 nm or more and 800 nm or less, and 200 nm or more and 800 nm or less. More preferably. When the particle diameter of the particulate polyolefin resin is larger than the film thickness of the image recorded on the recording medium, the image abrasion resistance can be improved. The average particle diameter of the polyolefin resin can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. As the particle size distribution measuring device, for example, a particle size distribution meter (for example, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle can be used.

  The polyolefin resin is not particularly limited as long as it can maintain a particle state of a predetermined particle diameter in an image recorded using the ink composition, and is an olefin such as ethylene, propylene, butylene, or a derivative thereof. And waxes produced from the above, and polyethylene wax, polypropylene wax, polybutylene wax and the like.

  As the polyolefin resin, a commercially available product can be used. “Chemical Pearl W4005” (manufactured by Mitsui Chemicals, Inc., polyethylene wax, particle size 200 to 800 nm, ring and ball method softening point 110 ° C., penetration method hardness 3, solid content 40%) and the like. These are commercially available in the form of an aqueous emulsion in which a polyolefin resin is dispersed in water by a conventional method. In the ink composition according to this embodiment, it can be directly added in the form of an aqueous emulsion. A polyolefin resin described in US Pat. No. 6,858,765 can also be suitably used.

(Ii) Modified polyolefin resin The modified polyolefin resin can reduce the transfer of an image to the back surface of the recording medium when the recording medium is overlaid, and can improve the abrasion resistance of the image. The reason why the abrasion resistance is improved is considered as follows. The modified polyolefin resin has an action of softening the ink coating film. Accordingly, it is considered that when pressure is applied to the image recording surface, the coating film itself is crushed, thereby increasing the binding force of the components in the ink and improving the abrasion resistance.

  Examples of the modified polyolefin resin include a modified polyethylene resin and a modified polypropylene resin. Examples of the modified polyethylene resin include oxidized polyethylene resin and (anhydrous) maleic acid modified polyethylene resin. Examples of the modified polypropylene resin include oxidized polypropylene resin and (anhydrous) maleic acid modified polypropylene resin. These resins can be used, for example, as an emulsion dispersed in a solvent such as water.

  Commercially available products can be used as the modified polyolefin resin, and AQUACER 515 (oxidized high-density polyethylene wax emulsion, particle size 100 to 200 nm, melting point 130 ° C., solid content 30%), AQUACER 507 (oxidized high-density polyethylene wax emulsion), AQUACER 526 (Modified ethylene vinyl acetate wax emulsion), AQUACER 593 (modified polypropylene wax emulsion) (manufactured by Big Chemie Japan Co., Ltd.), high wax 2203A (maleic anhydride modified polyethylene wax, manufactured by Mitsui Chemicals), Hitech E2213 ( Oxidized polyethylene wax emulsion, solid content 30%, manufactured by Toho Chemical Co., Ltd.) and the like.

(Iii) Sulfonic acid ester resin The sulfonic acid ester resin can suppress glossy spots generated when an image is rubbed. The sulfonic acid ester resin can be obtained, for example, by emulsion polymerization of an ethylenically unsaturated monomer in the presence of a reactive emulsifier (consisting of a hydrophilic group, a hydrophobic group, and a radical reactive group). The reactive emulsifier means an emulsifier having an emulsifying ability to the extent that emulsion polymerization is possible and capable of radical polymerization.

  The hydrophilic group of the reactive emulsifier may be at least a sulfate group, and is preferably both a sulfate group and a polyoxyethylene group.

  Examples of the hydrophobic group of the reactive emulsifier include an aliphatic alkyl group having 5 to 20 carbon atoms or an aromatic group. Among these, an aliphatic alkyl group having 8 to 15 carbon atoms can be preferably used. .

  Examples of the radical reactive group of the reactive emulsifier include an ethylenically unsaturated group such as an acryl group, a methacryl group, an allyloxy group, a methallyloxy group, and a propenyl group. Among these, an allyloxy group, A propenyl group is preferred.

  Commercially available products can be used as reactive emulsifiers, such as Latemuru S-180A (manufactured by Kao Corporation), Eleminol JS-2 (manufactured by Sanyo Chemical Co., Ltd.), Aqualon KH-10, Aqualon HS-10, Aqualon BC-10 ( Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SE-10N (Asahi Denka Kogyo Co., Ltd.), Aqualon RS-20 (Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap ER-20 (Asahi Denka Kogyo Co., Ltd.), etc. It can be suitably used. These reactive emulsifiers may be used alone or in combination of two or more.

  Although it does not specifically limit as an ethylenically unsaturated monomer, For example, 1,3-butadiene, isoprene, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, (meth ) (Meth) acrylic acid alkyl esters which are (meth) acrylic monomers such as 2-ethylhexyl acrylate, and among them, (meth) acrylic acid alkyl esters are preferred.

  The ethylenically unsaturated monomer may have a functional group such as an alkoxysilane group, an epoxy group, a hydroxyl group, or a polyethylene oxide group. By having such a functional group, the compatibility between the resin and each component in the ink composition can be improved. Among these, a monomer having an alkoxysilane group is particularly preferably used.

  As described above, the sulfonic acid ester resin can be obtained by emulsion polymerization of an ethylenically unsaturated monomer in the presence of a reactive emulsifier. For example, a method similar to that disclosed in US Patent Application Publication No. 2009/0304927. It is obtained with.

(Iv) Fluorene resin Fluorene resin can improve the fixability and abrasion resistance of recorded images. The fluorene resin is not particularly limited as long as it has a fluorene skeleton, and for example, a resin obtained by polymerizing the following monomers may be used.

5-Isocyanate-1- (isocyanatemethyl) -1,3,3-trimethylcyclohexane (CAS No. 4098-71-9)
2,2 ′-[9H-Fluorene-9-ylidenebis (4,1-phenyleneoxy)] bisethanol (CAS No. 117344-32-8)
3-Hydroxy-2- (hydroxymethyl) -2-methylpropionic acid (CAS No. 4767-03-7)
N, N-diethyl-ethanamine (CAS No. 121-44-8)
(3) Surfactant An anionic, nonionic or cationic surfactant is used as the surfactant, more preferably an acetylene glycol type, a fluorine type or an organopolysiloxane type, particularly an organopolysiloxane type surfactant. The agent can be preferably used, and when recording an image, the wettability to the surface of the recording medium can be increased to increase the ink permeability. The solubility of the organopolysiloxane surfactant in the ink composition is improved by the above-described poorly water-soluble alkanediol, water-soluble alkanediol, and the like. Thereby, since it can suppress that an insoluble matter etc. generate | occur | produce in an ink composition, the ink composition excellent in discharge stability can be obtained.

  As the organosiloxane surfactant as described above, commercially available ones may be used, for example, BKY-347, BKY-348, BYK-349 (above, manufactured by Big Chemie Japan Co., Ltd.) or the like. be able to.

  Moreover, you may use the compound represented by following General formula (1) as organopolysiloxane type surfactant.

  In the above formula (1), R is a hydrogen atom or a methyl group, a is an integer of 2 to 18, m is an integer of 0 to 70, and n is an integer of 1 to 8. R, a, m, and n preferably take the following combinations.

  R is a hydrogen atom or a methyl group, a is an integer of 2 to 13, m is an integer of 2 to 70, n is preferably an integer of 1 to 8, and R is a hydrogen atom or a methyl group. It is more preferable that a is an integer of 2 to 13, m is an integer of 2 to 50, and n is an integer of 1 to 8.

  R is a hydrogen atom or a methyl group, a is an integer of 2 to 13, m is an integer of 2 to 50, n is preferably an integer of 1 to 5, and R is a hydrogen atom or It is a methyl group, a is an integer of 2 to 11, m is an integer of 2 to 50, and n is more preferably an integer of 1 to 5.

  R is a methyl group, a is an integer of 6 to 18, m is an integer of 0 to 4, n is preferably 1 or 2, R is a methyl group, and a is 6 It is an integer of ˜18, m is 0, and n is more preferably 1.

  As surfactants other than those described above, acetylene glycol surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants and the like may be further added.

(4) Other components The ink composition of the present embodiment includes a nozzle clogging preventive agent, an antiseptic, an antioxidant, a conductivity adjusting agent, a pH adjusting agent, a viscosity adjusting agent, and a surface tension adjusting as necessary. An agent, an oxygen absorbent, etc. can be added.

1.2.6. Physical Properties The viscosity at 20 ° C. of the ink composition according to this embodiment is preferably 3 mPa · s or more and 10 mPa · s or less, and more preferably 3 mPa · s or more and 6 mPa · s or less. If the viscosity at 20 ° C. is within the above range, the ink can be suitably used for an ink jet recording apparatus because it can be discharged in an appropriate amount from the nozzle and can further reduce the occurrence of flight bending or scattering. The viscosity of the ink can be measured by keeping the temperature of the ink at 20 ° C. using a vibration viscometer VM-100AL (manufactured by Yamaichi Electronics Co., Ltd.).

  Further, the surface tension of the ink composition according to this embodiment at 20 ° C. is preferably 21 mN / m or more and 25 mN / m or less, and more preferably 22 mN / m or more and 24 mN / m or less. If the surface tension of the ink composition at 20 ° C. is within the above range, the ink composition attached to the ink low-absorbing recording medium is less likely to flow, and thus effectively suppresses image bleeding, density unevenness, and the like. be able to.

1.2.7. Method for Producing Ink Composition The ink composition according to the present embodiment is obtained by mixing the materials described above in an arbitrary order and removing impurities by filtering or the like as necessary.

  As a method for mixing the respective materials, a method in which the materials are sequentially added to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is preferably used. As a filtration method, centrifugal filtration, filter filtration, or the like can be performed as necessary.

1.3. Non-ink-absorbing or low-absorbing recording medium An ink-low-absorbing or non-absorbing recording medium is used in the ink jet recording method according to this embodiment. Examples of the ink low-absorbing or non-absorbing recording medium include printing paper such as art paper, coated paper, and matte paper. Here, the “ink non-absorbing or low-absorbing recording medium” in this specification means “the water absorption amount from the start of contact to 30 msec ^1/2 in the Bristow method is 10 mL / m ² or less. Recording medium ". This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method".

  In the ink jet recording method according to the present embodiment, since the above ink composition is used, an image with reduced ink repelling, image bleeding, shading unevenness, and the like is recorded on a non-ink-absorbing or low-absorbing recording medium. can get.

1.4. Inkjet Recording Method The inkjet recording method according to the present embodiment is performed using the ink composition described above. Further, the ink jet recording method according to the present embodiment can be carried out using the above-described ink jet recording apparatus.

  The ink jet recording method according to the present embodiment is not limited to this aspect, but in particular, after an image is continuously recorded on one surface of a plurality of ink non-absorbing or low-absorbing recording media, It is suitably used for an inkjet recording apparatus that records images continuously on the other surface of a plurality of non-ink-absorbing or low-absorbing recording media. The inkjet recording method according to the present embodiment includes at least a first image recording process, a stacking process, and a second image recording process, which will be described later, in this order, and before the second image recording process, a covering process and a removing process described later. At least one is provided. The ink jet recording method in the present embodiment will be described by taking an example in which two recording media (first recording medium and second recording medium) are used. However, the present invention is not limited to this, and three or more recording media are used. But you can do the same. Even when the ink jet recording method according to the present embodiment is performed using three or more recording media, the same effects as when two recording media are used are obtained. Hereinafter, each step will be described in detail.

1.4.1. First Image Recording Step The first image recording step is a step of recording an image by ejecting droplets of the ink composition from a nozzle and attaching the droplets to one surface of the first recording medium. The first image recording step can be performed as follows when the printer 1 described above is used.

  First, the first recording medium is moved by the medium feeding mechanism 8 and conveyed to a position where one surface of the first recording medium and a nozzle (not shown) provided in the head 2 face each other. Then, droplets of the ink composition are ejected from the nozzles of the head 2 to adhere the droplets to one surface of the first recording medium. In this way, an image is recorded on one surface of the first recording medium.

1.4.2. Coating process The coating process is a process in which an image recorded on one surface of the first recording medium is coated with a coating agent that does not substantially contain poorly water-soluble alkanediol. As will be described later, the coating agent preferably contains a resin and substantially does not contain a coloring material and a slightly water-soluble alkanediol.

  The timing at which the covering step is performed is performed before the second image recording step described later. Specifically, the covering step is preferably performed after the first image recording step and before the second image recording step, and more preferably after the first image recording and before the laminating step. .

  In the covering step, an image recorded on one surface of the first recording medium is coated with a coating agent, so that in the laminating step described later, the components contained in the image on one surface are recorded on the first recording medium in the second recording medium. It becomes difficult to adhere to the other surface of the medium. As a result, in the second image recording step described later, a good image with little reduction in color developability is recorded on the other surface of the second recording medium.

  In the ink jet recording method according to this embodiment, at least one of the covering step and the removing step described later may be performed, and both the covering step and the removing step described later may be performed.

  A method for coating an image using a coating agent is not particularly limited. For example, a method of discharging a coating agent from a nozzle of an inkjet recording apparatus (inkjet recording method) or an image using a coating apparatus such as a roll coater. The method of apply | coating a coating agent to the surface of this is mentioned.

  In the covering step, as long as an image recorded on at least one side of the first recording medium can be covered, the entire one side of the first recording medium may be covered. It is preferable to cover only the recording portion because the consumption of the coating agent can be reduced. In particular, when an ink jet recording method (a method in which a coating agent is ejected from a nozzle of an ink jet recording apparatus) is used, only the image recording portion can be easily covered, and the consumption of the coating agent can be reduced.

The amount of the coating agent to be one attached to the image recorded on the surface of the first recording medium is preferably at 1 mg / inch ² or more 4 mg / inch ² or less, 1.5 mg / inch ² or more 3.6 mg / Inch ² or less is more preferable. When the adhesion amount of the coating agent is within the above range, it is possible to record a good image with little reduction in color developability on the other surface of the second recording medium in the second image recording step described later.

  The coating agent does not substantially contain poorly water-soluble alkanediol. This is because an image recorded on the other surface of the second recording medium in the second image recording step described later tends to cause a decrease in color developability due to the above-mentioned poorly water-soluble alkanediol.

  Further, the coating agent does not substantially contain a color material. This is because when the coloring material is added to the coating agent, the hue of the image recorded on one surface of the first recording medium may change due to the adhesion of the coating agent.

  In the present invention, “substantially free of A” means that the meaning that A is not intentionally added when the ink composition is produced, or the significance of adding A is sufficiently achieved. It means that it is not added in excess of the amount. Specific examples of “substantially free” include, for example, 1.0% by mass or more, preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0% by mass. 0.05% by mass or less, particularly preferably 0.01% by mass or less, more preferably 0.001% by mass or less.

  The coating agent preferably contains a resin. When the coating agent contains a resin, an image recorded on one surface of the first recording medium can be satisfactorily covered, and volatilization of the slightly water-soluble alkanediol can be suppressed.

  As the resin to be added to the coating agent, the resins exemplified in the ink composition described above (“1.2.5. Other components (2) Resins”) can be used. Resin added to a coating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among the resins described above, it is preferable to use at least one of a sulfonic acid ester resin, a polyolefin resin, and a modified polyolefin resin as a resin to be added to the coating agent. The sulfonic acid ester resin, polyolefin resin and modified polyolefin resin can satisfactorily cover the image made of the ink composition and effectively suppress the appearance of poorly water-soluble alkanediol on the outermost surface of the image. Because.

  The content of the resin is preferably 1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 8% by mass or less with respect to the total mass of the coating agent. When the content of the resin is within the above range, the fixability to the image is good.

  The coating agent may contain components other than the above-mentioned components. For example, the coating agent may contain the components exemplified in the ink composition described above (except for the coloring material and the slightly water-soluble alkanediol). Good.

1.4.3. Removal Step The removal step is a step of removing a part of the components contained in the image recorded on one surface of the first recording medium. Since the timing at which the removal step is performed is the same as that in the covering step, the description thereof is omitted.

  In the removing step, by removing a part of the component included in the image recorded on one surface of the first recording medium, the component included in the image on one surface of the first recording medium is It becomes difficult to adhere to the other surface. As a result, in the second image recording step described later, a good image with little reduction in color developability is recorded on the other surface of the second recording medium.

  Examples of the component that reduces the color developability of the other surface of the second recording medium include the above-mentioned poorly water-soluble alkanediol.

  The method for removing the components contained in the image in the removing step is not particularly limited, and examples thereof include a method of drying the image and a method of directly removing the image by bringing it into contact with a removing member made of fabric, rubber or the like. Image drying can be done by a mechanism that heats the recording medium in contact with a heat source, a mechanism that irradiates infrared rays or microwaves (electromagnetic waves having a maximum wavelength of about 2,450 MHz), a mechanism that blows warm air, etc. It can be implemented using a drying mechanism.

  If the drying mechanism can be performed after the first image recording process and before the laminating process described later, the drying mechanism is provided at any position of the ink jet recording apparatus (for example, a paper discharge unit on which the recording media are stacked). However, it is preferably provided at a position where the droplets can be dried immediately after the droplets adhere to the recording medium. As described above, the position where the liquid droplet can be dried immediately after the liquid droplet is attached to the recording medium will be described in detail using the printer 1 described above. For example, the drying mechanism is located at a position facing the head 2. Is mentioned. As described above, when the drying mechanism is installed at a position facing the head 2, the droplets can be quickly dried at the same time as the first recording medium adheres, and the hardly water-soluble alkanediol can be volatilized immediately. As a result, it is possible to reduce adhesion of poorly water-soluble alkanediol to parts (such as a transporting roller) constituting the printer 1 by transporting the first recording medium. Therefore, the second recording medium is transported when the second recording medium is transported. The adhesion of poorly water-soluble alkanediol to the medium can be reduced. As a result, in the second image recording step, it is possible to record an image on which the color development deterioration is further reduced on the other surface of the second recording medium.

  The drying temperature and drying time by the drying mechanism can be appropriately set in consideration of the amount of droplets attached to the first recording medium, the transport speed of the first recording medium, etc., and are not particularly limited. .

1.4.4. Third Image Recording Step The ink jet recording method according to this embodiment preferably includes a third image recording step. The third image recording step is performed after the first image recording step, and a droplet of the ink composition is ejected from the nozzle, and the droplet is attached to one surface of the second recording medium to record an image. It is a process. Since the method for recording an image on the second recording medium is the same as the method for recording an image on the first recording medium, description thereof is omitted.

1.4.5. Lamination process The lamination process is performed after the first image recording process, and the first recording medium and the second recording medium are brought into contact with one surface of the first recording medium and the other surface of the second recording medium. This is a step of laminating media. The stacking step can be performed as follows when the printer 1 described above is used.

  First, after the first image recording step and the covering step, the first recording medium is conveyed to a medium placement area (not shown) by the medium feeding mechanism 8 and one of the first recording media is placed on the medium placement area. Placed face up. In addition, although the example which implements a coating process was shown here, it may replace with a coating process and a removal process may be performed, and both a coating process and a removal process may be performed.

  Next, after the third image recording step, the second recording medium is transported to the medium placement area in the same manner as the first recording medium, and is laminated on the first recording medium in the medium placement area (lamination step). As a result, one surface of the first recording medium comes into contact with the other surface of the second recording medium (a surface on which no image is recorded yet). In this way, on the other surface of the second recording medium, the first area in contact with the image recorded on one surface of the first recording medium and the image recorded on one surface of the first recording medium. And a second region that does not touch the surface.

  Here, in the image recorded on one surface of the first recording medium, the hardly water-soluble alkanediol included in the image is hardly generated on the surface of the image by the coating process (removal process). For this reason, in the laminating step, the hardly water-soluble alkanediol derived from the image of the first recording medium is unlikely to adhere to the first region of the second recording medium.

  In addition, although the case where the lamination process is performed after the third image recording process is shown, the lamination process may be performed before the third image recording process, or the third image recording process is not performed after the first image recording process. A stacking step may be performed.

1.4.6. Fourth Image Recording Step The ink jet recording method according to this embodiment preferably includes a fourth image recording step. The fourth image recording step is performed after the laminating step, and is a step of recording an image by ejecting droplets of the ink composition from the nozzle and attaching the droplets to the other surface of the first recording medium. is there. For example, when the printer 1 described above is used, the fourth image recording step can be performed as follows.

  The first recording medium and the second recording medium stacked in the stacking process are reversed manually or by a reversing device (not shown) and moved to the paper feed unit, or the first recording medium is reversed and reversed. Record again. If the former method is adopted, the first recording medium is laminated on the second recording medium, and the other side of the first recording medium and the second recording medium on which no image has been recorded is Look upwards.

  Next, the first recording medium and the second recording medium are conveyed to a paper feed unit (not shown), and recording of an image on the other surface of the first recording medium is started. Since the method for recording an image on the first recording medium is the same as that in the first image recording step, description thereof is omitted.

  By the first image recording step and the fourth image recording step, a recording medium (recorded material) on which images are recorded on both surfaces (one surface and the other surface) of the first recording medium can be obtained.

1.4.7. Second image recording step The second image recording step is performed after the laminating step, and the droplets of the ink composition are ejected from the nozzles, and the droplets are adhered to the other surface of the second recording medium. Is a step of recording. Since the method for recording an image on the second recording medium is the same as that in the fourth image recording step, the description thereof is omitted.

  The second image recording process may be performed after the lamination process, may be performed after the fourth image recording process described above, or may be performed before the fourth image recording process.

  By the second image recording step and the third image recording step, a recorded matter in which images are recorded on both surfaces (one surface and the other surface) of the second recording medium can be obtained.

1.5. Effects According to the ink jet recording method according to the present embodiment, an image having excellent color developability can be recorded by having the covering step or the removing step.

  Further, according to the ink jet recording method according to the present embodiment, the component (particularly poorly water-soluble alkanediol) derived from the image recorded on the first recording medium adheres to the first region of the second recording medium. Few. As a result, the recorded matter obtained by the ink jet recording method according to the present embodiment has little variation in color developability in the image when the same amount of the ink composition is adhered to the same surface of the recording medium. , With a good image.

  Specifically, in the second image recording step, an image recorded on the other surface of the second recording medium is recorded by attaching the same amount of the ink composition to the first area and the second area. In this case, it is preferable that the difference in the OD value between the first region and the second region is less than 0.05. Here, the OD value (Optical Density) indicates an index of color developability of an image, and can be measured using a spectrophotometer (for example, “GRETAG SPM50” manufactured by Gretag Macbeth).

  In the ink jet recording method according to the present embodiment, preferably, images are continuously recorded on one surface of a plurality of recording media, and then images are continuously recorded on the other surface of the plurality of recording media. If this method is adopted, when performing double-sided printing of a large number of recording media, if the recording method of this embodiment is adopted, a plurality of recording media can be used rather than double-sided printing of a plurality of recording media one by one. Can be printed at high speed.

2. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

2.1. Preparation of ink composition The components shown in Table 1 were mixed and stirred to obtain an ink composition. In addition, each component shown in Table 1 is as follows.

(Pigment)
・ Black pigment (Pigment Black 7)
(Dispersed resins)
・ Styrene acrylic resin (weight average molecular weight 8000, acid value 150)
Fluorene resin (containing about 50% by mass of a monomer having a fluorene skeleton represented by CAS No. 117344-32-8 in a monomer composition ratio, weight average molecular weight 3300)
(Slightly water-soluble alkanediol)
・ 1,2-octanediol (water-soluble alkanediol)
・ 1,2-Hexanediol ((Poly) oxyalkylene glycol)
・ Dipropylene glycol (surfactant)
-Polyorganosiloxane-based surfactant (in the above formula (1), R is a methyl group, a is an integer of 9 to 13, m is an integer of 2 to 4, and n is an integer of 1 to 2, In the above formula (1), R is a hydrogen atom, a is an integer of 7 to 11, m is an integer of 30 to 50, and n is an integer of 3 to 5, and a surfactant)

2.2. Preparation of coating agent Each component shown in Table 2 was mixed and stirred to obtain coating agents 1 to 3. Of the components shown in Table 2, components other than those used in the ink composition of Table 1 are shown below.

(Resin)
・ Modified polyolefin resin (trade name “AQUACER 515”, manufactured by Big Chemie Japan, oxidized high density polyethylene wax emulsion)
・ Polyolefin resin (trade name “CHEMIPARL W4005”, manufactured by Mitsui Chemicals, Inc.)
・ Sulfonate resin (see below)
The sulfonic acid ester resin was prepared by the following method.

The following components were charged into a 2 liter beaker and stirred at 100 rpm for 10 minutes to obtain a monomer emulsion.
(Ethylenically unsaturated monomer)
・ Methyl methacrylate 348 g (58 parts by mass), butyl acrylate 240 g (40 parts by mass), acrylic acid 12 g (2 parts by mass)
(Reactive emulsifier)
・ Aqualon KH-10 15% aqueous solution 30g (Daiichi Kogyo Seiyaku Co., Ltd., containing sulfate group and polyoxyethylene group)
(Chain transfer agent)
・ 6-ethylhexyl thioglycolate 6g
(water)
・ Pure water 450g
Next, 520 g of water and 90 g of a 15% aqueous solution of the same reactive emulsifier as above are put into a 2 L separable flask, heated to 60 ° C. while stirring at 180 rpm, charged with 2 g of ammonium persulfate and heated to 70 ° C. did.

  In this reactive emulsifier aqueous solution, the monomer emulsion obtained above was sequentially added for 3 hours while maintaining the polymerization temperature of 75 ° C. to carry out emulsion polymerization. Thereafter, the polymerization solution was heated to 80 ° C. and aged for 1 hour, and then cooled. Subsequently, 10% ammonia aqueous solution was added to the polymerization solution for neutralization, and the pH was adjusted to 7.3.

When the average particle diameter film forming temperature and the weight average molecular weight (Mw) of the obtained polymer fine particles were measured, the average particle diameter was 50 nm, the film forming temperature was 15 ° C., and Mw = 45,000. . The average particle diameter was measured using Photo PAR-III (manufactured by Otsuka Electronics Co., Ltd.), and the film forming temperature was measured using a film forming temperature tester (manufactured by Rigaku Corporation). The weight average molecular weight was measured using a GPC apparatus (SC8010 (GPC), manufactured by Tosoh Corporation) using standard polystyrene as a calibration curve. The measurement conditions were as follows.
Eluent: Tetrahydrofuran Column: G4000HXL (manufactured by Tosoh Corporation)
・ Flow rate: 1000 μL / min ・ Column temperature: 40 ° C.

2.3. Evaluation test 2.3.1. Example 1
(Preparation of evaluation sample of Example 1)
The ink composition and the coating agents 1 to 3 obtained as described above were filled in a dedicated cartridge of an ink jet printer (trade name PX-G930, manufactured by Seiko Epson Corporation) and mounted on the printer.

(First image recording step) Then, the ink composition is ejected from the nozzle of the printer, and on one side of the first recording medium (trade name “OK Top Coat Plus”, manufactured by Oji Paper Co., Ltd., printing paper) An 8 × 10 cm rectangular patch was printed. Note that the printing conditions at this time were an image resolution of 720 × 720 dpi, a dot weight of 7 ng (per dot), and an ink ejection amount of 3.6 mg / inch ² .

(Coating process) Next, the coating agent 1 was discharged from the nozzles of the printer to coat the rectangular patches printed on the first recording medium. The printing conditions at this time are as follows: image resolution 720 × 720 dpi, dot weight 7 ng (per dot), and the coating amount of coating agent 1 is 1.0 mg / inch ² , 1.5 mg / inch ² , 3.6 mg / inch ² .

(Lamination process) Then, one surface of the first recording medium having a rectangular patch coated with the coating agent 1 and the second recording medium (trade name “OK Top Coat Plus”, manufactured by Oji Paper Co., Ltd., printing paper) The other surface (unprinted surface) was overlaid and a load of 65 g / cm ² was applied for 10 minutes. As a result, on the other surface of the second recording medium, a first area that is in contact with the rectangular patch of the first recording medium and a second area that is not in contact with the rectangular patch of the first recording medium are formed. .

(Second image recording step) After 10 minutes, the ink composition was ejected from the nozzles of the printer onto the other surface of the second recording medium to print a solid pattern image. Thus, the evaluation sample of Example 1 was created. The printing conditions at this time were an image resolution of 720 × 720 dpi, a dot weight of 3 ng (per dot), and an ink ejection amount of 1.5 mg / inch ² .

(Measurement of in-plane difference of OD value)
The OD value of each of the first region and the second region of the evaluation sample (second recording medium) obtained in this way is measured, and the difference between these (the OD value in-plane difference) is obtained. It was. For the measurement of the OD value, a spectrophotometer (trade name “GRETAG SPM50”, manufactured by Gretag Macbeth) was used.

(Measurement of in-plane color difference)
Further, the color difference (ΔE) between the first area of the second recording medium and the second area of the second recording medium was measured, and this was defined as the in-plane color difference (ΔE). A spectrophotometer (trade name “GRETAG SPM50”, manufactured by Gretag Macbeth Co., Ltd.) was used for the measurement of the color difference.

2.3.2. Example 2
In the preparation of the evaluation sample of Example 2, the “(Evaluation sample of Example 1) was performed except that the following (removal step) was performed instead of the (lamination step) in the“ creation of the evaluation sample of Example 1 ”. ) ”). For the evaluation sample of Example 2 obtained in this way, the in-plane difference and in-plane color difference of the OD values were determined in the same manner as in Example 1.

(Removal process)
Apply a rectangular patch printed on the first recording medium by applying warm air of 80 ° C. for 10 seconds to the rectangular patch printed on the first recording medium obtained in the same manner as in the above (first image recording step). Heated and dried.

2.3.3. Example 3
In the preparation of the evaluation sample of Example 3, the above described “2.3.2. Example” except that the time for applying the warm air in the removal step in “2.3.2. Example 2” was set to 20 seconds. 2 ”. With respect to the evaluation sample of Example 3 obtained in this way, the in-plane difference and in-plane color difference of the OD values were determined in the same manner as in Example 1.

2.3.4. Example 4
In the preparation of the evaluation sample of Example 4, the “2.3.2. Example” described above except that, in the removal step in “2.3.2. Example 2”, the time for applying hot air was set to 30 seconds. 2 ”. With respect to the evaluation sample of Example 4 obtained in this way, the in-plane difference and in-plane color difference of the OD values were determined in the same manner as in Example 1.

2.3.5. Comparative Example 1
The preparation of the evaluation sample of Comparative Example 1 was performed in the same manner as “(Preparation of the evaluation sample of Example 1)” except that the coating agent 2 was used instead of the coating agent 1. With respect to the evaluation sample of Comparative Example 1 obtained in this manner, the in-plane difference and in-plane color difference of the OD values were determined in the same manner as in Example 1.

2.3.6. Comparative Example 2
Preparation of the evaluation sample of Comparative Example 2 was performed in the same manner as “(Preparation of evaluation sample of Example 1)” except that the coating agent 3 was used instead of the coating agent 1. With respect to the evaluation sample of Comparative Example 2 obtained in this manner, an in-plane difference and an in-plane color difference of OD values were obtained in the same manner as in Example 1.

2.3.7. Comparative Example 3
The preparation of the evaluation sample of Comparative Example 3 was performed in the same manner as the above “(Preparation of the evaluation sample of Example 1)” except that the coating step was not performed. With respect to the evaluation sample of Comparative Example 3 thus obtained, an in-plane difference and an in-plane color difference of OD values were determined in the same manner as in Example 1.

2.4. Evaluation Results The evaluation results of Example 1, Comparative Example 1, and Comparative Example 2 are shown in Table 3, and the evaluation results of Example 2, Example 3, Example 4, and Comparative Example 3 are shown in Table 4.

  As shown in Table 3 and Table 4, the images obtained by creating the evaluation samples of Examples 1 to 4 (images recorded on the other surface of the second recording medium) all have OD values. The in-plane difference was within 0.05, the in-plane color difference was small, and it was shown to be good.

  On the other hand, the coating agent 2 and the coating agent 3 used for preparing the evaluation samples of Comparative Example 1 and Comparative Example 2 both contained poorly water-soluble alkanediol (1,2-octanediol). Therefore, both the images obtained by creating the evaluation samples of Comparative Example 1 and Comparative Example 2 (images recorded on the other surface of the second recording medium) have an in-plane difference in OD value of 0.05. In addition, the in-plane color difference was very high.

  In addition, in the creation of the evaluation sample of Comparative Example 3, the covering step and the removing step described above are not performed. For this reason, adhesion of components due to the image recorded on the first recording medium was recognized in the first area of the second recording medium in the above-described lamination step. In addition, when the component adhering to the first region was analyzed by a gas chromatograph mass spectrometer (GC-MS) (manufactured by Shimadzu Corporation, trade name “GCMS-QP5000”), it was mainly 1,2-octanediol. As a result, all the images obtained by creating the evaluation samples of Comparative Example 3 (images recorded on the other surface of the second recording medium) have an in-plane difference of OD values exceeding 0.05. In addition, the in-plane color difference was very high.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Head, 3 ... Ink cartridge, 4 ... Carriage, 5 ... Platen, 7 ... Carriage moving mechanism, 8 ... Medium feed mechanism, 9 ... Guide rod, 10 ... Linear encoder, CONT ... Control device

Claims (8)

An inkjet recording method for recording an image on the surface of a plurality of non-absorbing or low-absorbing recording media,
A droplet of an ink composition containing a hardly water-soluble alkanediol, a water-soluble alkanediol, a coloring material, and water is ejected from a nozzle, and the droplet is applied to one side of the first recording medium. A first image recording step of recording an image attached to the
A laminating step of laminating the first recording medium and the second recording medium by bringing one surface of the first recording medium into contact with the other surface of the second recording medium;
A second image recording step of recording an image by discharging droplets of the ink composition from the nozzle and attaching the droplets to the other surface of the second recording medium;
In this order,
Before the second image recording step,
A coating step of coating an image recorded on one side of the first recording medium with a coating agent that does not substantially contain a slightly water-soluble alkanediol;
And an ink jet recording method comprising at least one of a removing step of removing a part of the component contained in the image recorded on one surface of the first recording medium. In claim 1,
By the laminating step, recording is performed on the other surface of the second recording medium on the first surface of the first recording medium and the first region in contact with the image recorded on the one surface of the first recording medium. A second region that does not contact the rendered image,
In the second image recording step, when an image is recorded by attaching the same amount of the ink composition to the first area and the second area, the OD values of the first area and the second area are An ink jet recording method, wherein the difference is less than 0.05. In claim 1 or claim 2,
A third image recording step of recording an image by discharging droplets of the ink composition from the nozzle and attaching the droplets to one surface of the second recording medium;
And a fourth image recording step of recording an image by ejecting droplets of the ink composition from the nozzle and attaching the droplets to the other surface of the first recording medium. In any one of Claims 1 thru | or 3,
After continuously recording images on one side of the plurality of non-ink-absorbing or low-absorbing recording media, continuously on the other side of the plurality of non-absorbing or low-absorbing recording media An ink jet recording method for recording an image. In any one of Claims 1 thru | or 4,
The ink jet recording method, wherein the coating agent contains a resin and does not substantially contain a coloring material and a hardly water-soluble alkanediol. In claim 5,
The inkjet recording method, wherein the resin contained in the coating agent is at least one selected from a sulfonate resin, a polyolefin resin, and a modified polyolefin resin. In any one of Claims 1 thru | or 6,
Removal in the removing step is an ink jet recording method in which an image recorded on one surface of the first recording medium is dried.   A recorded matter recorded by the ink jet recording method according to claim 1.

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