JP6962001B2 - Recording method and recording device - Google Patents

Description

The present invention relates to a recording method and a recording device.

An inkjet recording method for recording an image on a recording medium by ejecting minute ink droplets from a nozzle of a recording head of an inkjet recording device is known, and its use in the field of signature printing and high-speed label printing is also being considered. There is. Then, when recording an image on a recording medium having low ink absorption (for example, art paper or coated paper) or a recording medium having no ink absorption (for example, plastic film), an ink composition (hereinafter, "ink") is used. In addition to using non-aqueous solvent-based ink compositions, the use of aqueous ink compositions containing resin emulsions is being studied from the viewpoint of global environment and safety to the human body. ..

When printing with these inks, the recording medium is heated by the platen heater during recording (primary drying) for the purpose of improving the fixability and drying property of the ink, or the drying provided separately from the platen heater after recording. The recording medium is heated (secondary drying) in the furnace. Here, when the ink on the recording medium is dried, a recording method having excellent image quality and / or abrasion resistance is known by controlling the temperature according to the amount of ink applied and the temperature of the platen heater (). For example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2015-205476 Japanese Unexamined Patent Publication No. 2013-28093

However, in the above technique, the temperature until the recording medium enters the drying oven after recording is not controlled, and the temperature drops sharply in the transport path of the recording medium. Then, since the recording medium whose temperature has once dropped is rapidly heated in the drying furnace, the recording medium may be deformed due to a sudden temperature change. In addition, dew condensation may occur on the surface of the medium, resulting in inferior abrasion resistance of the recorded image. In particular, in the case of a recording medium formed of a plurality of layers such as an adhesive medium, a difference in volume expansion occurs between the layers, so that the amount of deformation becomes large and the recording medium may be twisted.

Therefore, some aspects of the present invention provide a recording method in which deformation of the recording medium can be prevented and image quality and / or abrasion resistance are excellent by solving at least a part of the above-mentioned problems.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following aspects or application examples.

[Application example 1]
One aspect of the recording method according to the present invention is
The ink composition adhesion step of adhering the ink composition to the recording medium and the process of adhering the ink composition to the recording medium.
A primary drying step of heating the surface temperature of the recording medium at the time of adhesion of the ink composition to the recording medium to a primary drying temperature, and
A transport step of transporting the recording medium subjected to the ink composition adhesion step to the secondary drying means, and a transport step.
The secondary drying means comprises a secondary drying step of heating the surface temperature of the recording medium to the secondary drying temperature.
From the completion of adhesion of the ink composition to the recording medium to the completion of the secondary drying step, the minimum temperature change of the surface temperature of the recording medium with respect to the primary drying temperature (° C.) is −40% or more. The maximum temperature change is 370% or less,
The average rate of temperature rise from the completion of adhesion of the ink composition to the recording medium until the surface temperature of the recording medium reaches the secondary drying temperature is 7 (° C./s) or less. do.

According to the recording method of Application Example 1, by controlling the surface temperature of the recording medium after the ink composition adhesion step so as to be within a predetermined temperature change, the dimensional change due to thermal expansion of the recording medium is prevented. Further, by controlling the surface temperature of the recording medium so as to be within a predetermined temperature change, the ink is sufficiently dried in the transport path, so that the obtained image quality and the scratch resistance of the image are also improved. Further, since the minimum temperature change of the surface temperature of the recording medium with respect to the primary drying temperature (° C.) is −40% or more and the maximum temperature change is 370% or less, heat is not wasted and energy is saved.

[Application example 2]
In the above application example
The medium width of the recording medium can be 350 mm or more.

In the present invention, the above effects can be obtained even in a recording medium in which the medium width of the recording medium is 350 mm or more.

[Application example 3]
In the above application example
The minimum temperature change can be −35% or more.

According to Application Example 3, when the minimum temperature change is −35% or more, heat is not wasted, deformation of the recording medium can be further prevented, and a recording method having excellent image quality and / or abrasion resistance is provided. Can be done.

[Application example 4]
In the above application example
The secondary drying temperature can be equal to or higher than the primary drying temperature.

According to Application Example 4, when the secondary drying temperature is equal to or higher than the primary drying temperature, the ink is dried, deformation of the recording medium can be further prevented, and a recording method having excellent image quality and / or abrasion resistance can be provided. can.

[Application example 5]
In the above application example
The time from the completion of adhesion of the ink composition to the recording medium to reaching the secondary drying temperature can be within 250 seconds.

According to Application Example 5, deformation of the recording medium can be further prevented by setting the time from the completion of adhesion of the ink composition to the recording medium to reaching the secondary drying temperature within 250 seconds, and the image quality and image quality can be improved. Alternatively, it is possible to provide a recording method having excellent scratch resistance.

[Application example 6]
In the above application example
The primary drying temperature can be 30 ° C. or higher and 60 ° C. or lower, and the secondary drying temperature can be 50 ° C. or higher and 160 ° C. or lower.

According to Application Example 6, the drying temperature suppresses ink bleeding, and the image quality is excellent, and the scratch resistance of the obtained image is also excellent.

[Application 7]
In the above application example
In the transfer step, at least one of a heating means and a heat retaining means can be provided in the transfer path to which the recording medium is conveyed.

According to Application Example 7, by providing at least one of the heating means and the heat retaining means in the transport path, it is possible to adjust the temperature so that the surface temperature of the recording medium does not drop in the transport path.

[Application Example 8]
In the above application example
The recording medium can be a recording medium with a release paper.

According to Application Example 8, even when the recording medium is a recording medium with a release paper, the occurrence of a volume expansion difference between the release paper and the recording medium can be suppressed to prevent deformation of the recording medium, and the image quality and image quality can be improved. Alternatively, it is possible to provide a recording method having excellent scratch resistance.

[Application example 9]
In the above application example
The time from the completion of adhesion of the ink composition to the recording medium until the recording medium is conveyed to the secondary drying means and reaches the secondary drying temperature can be 60 seconds or less.

According to Application Example 9, it is possible to provide a recording method capable of further preventing deformation of the recording medium and having excellent image quality and / or abrasion resistance.

[Application Example 10]
In the above application example
The length of the transport path from the point where the adhesion of the ink composition to the recording medium is completed until the secondary drying temperature is reached can be 500 mm or less.

According to Application Example 10, it is possible to provide a recording method capable of further preventing deformation of the recording medium and having excellent image quality and / or abrasion resistance.

[Application Example 11]
In the above application example
The ink composition may be a water-based ink composition containing a coloring material, water, a resin, and a water-soluble organic solvent, or a solvent-based ink composition containing a coloring material and an organic solvent.

According to Application Example 11, in the recording method using the ink composition as described above, it is possible to provide a recording method capable of preventing deformation of the recording medium and having excellent image quality and / or abrasion resistance.

[Application 12]
In the above application example
The ink composition can be an aqueous ink composition containing an organic solvent having a standard boiling point of more than 280 ° C. and an organic solvent having a standard boiling point of 150 ° C. or higher and 280 ° C. or lower in an amount of 3% by mass or less.

According to Application Example 12, in the recording method using the ink composition as described above, it is possible to provide a recording method capable of preventing deformation of the recording medium and having excellent image quality and / or abrasion resistance.

[Application 13]
In the above application example
The ink composition adhesion step can be performed by ejecting the ink composition from the inkjet head.

According to Application Example 13, when the ink composition adhesion step is performed by ejecting the ink composition from the inkjet head, deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or scratch resistance is provided. can do.

[Application 14]
In the above application example
Recording can be performed on either non-absorbent or low-absorbency recording media.

According to Application Example 14, even when recording is performed on either non-absorbent or low-absorbency recording medium, deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or scratch resistance is provided. be able to.

[Application Example 15]
In the above application example
A step of adhering a reaction solution containing a flocculant that aggregates the components of the ink composition to the recording medium can be provided.

According to Application Example 15, even in a recording method using a reaction solution, deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or abrasion resistance can be provided. In addition, a higher quality image can be formed by the agglutinating action of the aggregating agent.

[Application 16]
In the above application example
The maximum amount of the ink composition adhered to the adhering region of the recording medium can be 3 mg / inch ² or more.

According to Application Example 16, even when the adhesion amount of the ink composition is 3 mg / inch ² or more, deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or scratch resistance can be provided.

[Application example 17]
In the above application example
The primary drying temperature can be 40 ° C. or lower, and the minimum temperature change can be −10% or higher.

According to Application Example 17, when the primary drying temperature is 40 ° C. or lower and the minimum temperature change is -10% or more, deformation of the recording medium can be further prevented, and a recording method having excellent image quality and / or abrasion resistance can be obtained. Can be provided.

[Application Example 18]
One aspect of the recording device according to the present invention is
It is characterized in that recording is performed by the recording method described in any one of Application Example 1 to Application Example 17.

According to Application Example 18, by recording by the recording method described in the above application example, deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or abrasion resistance can be provided.

The side view which shows typically the inkjet printer used for the recording method which concerns on embodiment of this invention. The figure which shows the change of the surface temperature of a recording medium in the recording method which concerns on embodiment of this invention.

Some embodiments of the present invention will be described below. The embodiments described below describe an example of the present invention. The present invention is not limited to the following embodiments, and includes various modifications implemented without changing the gist of the present invention. It should be noted that not all of the configurations described below are essential configurations of the present invention.

In the recording method according to the present embodiment, the surface temperature of the recording medium at the time of adhering the ink composition to the recording medium and the step of adhering the ink composition to the recording medium is set to the primary drying temperature. The surface temperature of the recording medium is secondarily dried by the primary drying step of heating up to, the transport step of transporting the recording medium subjected to the ink composition adhesion step to the secondary drying means, and the secondary drying means. A secondary drying step of heating to a temperature is provided, and the primary drying temperature of the surface temperature of the recording medium from the completion of adhesion of the ink composition to the recording medium to the completion of the secondary drying step. The minimum temperature change with respect to (° C.) is −40% or more, the maximum temperature change is 370% or less, and the surface temperature of the recording medium becomes the secondary drying from the completion of adhesion of the ink composition to the recording medium. The average rate of temperature rise until the temperature is reached is 7 (° C./s) or less.

Hereinafter, the recording method according to the present embodiment will be described in the order of a recording device for recording by this recording method, an ink composition (hereinafter, also referred to as “ink”), a reaction solution, a recording medium, and a recording method.

1. 1. Recording device An example of a recording device in which the recording method according to the present embodiment is implemented will be described with reference to the drawings. The recording device that can be used in the recording method according to the present embodiment is not limited to the following aspects.

In addition, in each of the following figures, in order to make the explanation easier to understand, they may be described on a scale different from the actual one, and in the coordinates added to the drawings, the Z-axis direction is the vertical direction and the + Z direction is the upward direction. , The Y-axis direction is the front-back direction, and the + Y direction is the front direction. In the following description, even if expressions that are originally strictly understood such as orthogonal, parallel, and constant are used, they do not mean only strictly orthogonal, parallel, and constant, and in terms of device performance. It means that it includes an allowable error and an error that can occur when manufacturing the device.

Examples of the recording device used in the present embodiment include an inkjet printer (hereinafter, also simply referred to as “printer”) as shown in FIG.

FIG. 1 is a side view schematically showing a printer 100 as a “recording device” according to the present embodiment. The printer 100 can set a plurality of roll papers (recording media) 1 supplied in a rolled state as a "recording medium" in parallel, and record an image on the plurality of roll papers 1 (a plurality of roll papers 1). It is a multi-roll inkjet printer that can print).

The printer 100 includes a recording unit 10, a transport unit 20, a supply unit 30, a winding unit 40, a transport path (convey path) 50, a preheating section 60, a first heating section (primary drying means) 70, and a second heating. A unit (secondary drying means) 80, a control unit 90, and the like are provided. The recording unit 10, the preheating unit 60, and the first heating unit 70 of the printer 100 are configured to be provided in the housing 75, and the entire drive of the printer 100 is controlled by the control unit 90.

The roll paper 1 is supplied from the supply unit 30, passes through the recording unit 10 by the transport path 50 along with the recording, and is stored in the winding unit 40. As the roll paper 1, for example, high-quality paper, cast paper, art paper, coated paper, synthetic paper, and a film made of PET (polyethylene terephthalate), PP (polypolylone), or the like can be used as the roll paper 1. can. Further, as the roll paper 1, a label paper in which a plurality of labels are attached at intervals to a strip-shaped release paper (roll paper) can also be used.

The recording unit 10 includes a recording head 11, a carriage 12, a guide shaft (not shown), and the like. The recording head 11 is an inkjet head including a plurality of nozzles for ejecting ink droplets as "droplets" and reaction droplets. The area where the recording head 11 faces the roll paper 1 becomes the printing area.

As the recording head 11, a conventionally known method can be used. As an example of a known method, for example, a head that ejects droplets by utilizing the vibration of a piezoelectric element, that is, a head that forms ink droplets by mechanical deformation of an electrostrictive element can be mentioned. The guide shaft extends in the scanning direction intersecting the transport direction X in which the roll paper 1 moves. The carriage 12 is equipped with a recording head 11, and is reciprocated (scanned) along a guide axis by a carriage motor (not shown) driven and controlled by a control unit 90. In this way, while moving the carriage 12 in the scanning direction, the operation of ejecting ink droplets from the recording head 11 and the transport operation of moving the roll paper 1 in the transport direction X by the transport unit 20 are alternately repeated. A desired image is formed (recorded) on the roll paper 1.

In the present embodiment, the recording unit 10 is configured by a serial head that reciprocates in the scanning direction, but the roll paper 1 can be set in a direction in which the nozzle for ejecting ink intersects the transport direction X. The line heads may be arranged over a range. Further, the printer may have a recording unit other than the so-called inkjet recording head as described above.

The transport unit 20 is a transport mechanism that moves the roll paper 1 in the transport direction X in the recording section 10, and is configured to include two sets of a pair of rollers 21A and 21B. The rollers 21A and 21B are configured to be rotatable so that their outer circumferences are in contact with each other. The rollers 21A and 21B are rotationally driven by power from a motor (not shown) controlled by the control unit 90. Then, the roll paper 1 is conveyed along the conveying path 50 by rotationally driving the rollers 21A and 21B in a state where the roll paper 1 is sandwiched between the rollers 21A and 21B. The transport unit 20 is not limited to the configuration using these rollers, and may be configured by, for example, a transport belt or the like.

The supply unit 30 is an accommodating unit for accommodating the roll paper 1 before recording is performed, is located on the upstream side of the recording unit 10 in the transport path 50, and includes a feeding shaft 31 and the like. The feeding shaft 31 is rotated by a feeding motor (not shown) driven and controlled by the control unit 90, and the set roll paper 1 is fed toward the recording unit 10 arranged on the downstream side of the supply unit 30.

The winding unit 40 is a storage unit that winds up the roll paper 1 for which recording has been completed and stores it in a rolled state. It is located on the downstream side of the recording unit 10 in the transport path 50, and the winding shaft 41. And so on. The take-up shaft 41 is a rotary shaft that is rotated by a take-up motor (not shown) that is driven and controlled by the control unit 90, and winds the roll paper 1 sent through the recording unit 10 with the rotary shaft as the axis. take.

The transport path 50 is a transport path for transporting the roll paper 1 from the supply unit 30 to the winding unit 40 via the recording unit 10, and the medium support unit 62 and the platen that support the roll paper 1 in the recording unit 10. It is composed of 72, a medium support portion 82, and the like.

The preheating unit 60 is a portion that preheats (preheats) the surface of the roll paper 1 before recording is performed (that is, before ink droplets are applied), and is located downstream of the supply unit 30 in the transport path 50. It is located on the upstream side of the recording unit 10. By preheating the roll paper 1 before ejecting the ink composition, a high-quality image with less bleeding can be obtained, especially when the roll paper 1 as a recording medium is a non-absorbent and low-absorbency recording medium. Can be formed. In this case, the preheating temperature is preferably 30 to 60 ° C.

The preheating unit 60 has a preheating unit 61 for heating or heat retention, and the preheating unit 61 is arranged at a position facing the surface of the roll paper 1 supported and conveyed by the medium support unit 62. Has a heater. This heater may be configured by using, for example, a heat generating resistor, and may further include a reflector for efficiently irradiating the roll paper 1 with infrared rays radiated by the heater. Further, the medium support portion 62 may be provided with a heater. In FIG. 1, the preheating unit 61 and the medium support portion 62 have the same length in the Y-axis direction, and the entire region heated by the preheating unit 61 is the preheating region.

The first heating unit 70 is a portion that heats the surface temperature of the roll paper 1 when the ink droplets are applied to the primary drying temperature, and is a winding unit 40 on the downstream side of the preheating unit 60 in the transport path 50. It is located on the upstream side of. The first heating unit 70 may have a structure in which the platen 72 has a heater at a position facing the recording head 11 (for example, a platen heater), or a structure in which the recording head 11 has a heater (for example, an IR heater). May be good. These heaters preferably heat the roll paper 1 so that the surface temperature (primary heating temperature) of the roll paper 1 is 30 ° C. or higher when the ink composition is ejected to the roll paper 1 as a recording medium. As a result, the ink composition adhering to the roll paper 1 can be dried more quickly and bleeding can be suppressed.

The platen heater and the IR heater heat the surface of the roll paper 1 which is the recording medium when the ink composition is ejected from the recording head 11, and the IR heater heats the recording medium from the recording head 11 side. can do. As a result, the recording head 11 is likely to be heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium as compared with the case where the recording head 11 is heated from the back surface of the recording medium such as a platen heater. On the other hand, the platen heater can heat the recording medium from the side opposite to the recording head 11 side. As a result, the recording head 11 is relatively less likely to be heated, and the nozzles of the recording head 11 are less likely to be clogged. Then, the entire region heated by the platen heater or IR heater becomes the primary heating region.

The second heating unit 80 is a portion for heating and drying (secondary heating) the roll paper 1 on which recording has been performed (that is, to which ink droplets have been applied), and is downstream of the recording unit 10 in the transport path 50. It is located on the upstream side of the take-up portion 40 on the side. By this secondary heating, water and the like contained in the ink composition adhering to the surface of the recording medium on which the image is recorded evaporates and scatters more quickly, and a film is formed by the resin and the like contained in the ink composition. NS. In this way, the dried ink is firmly fixed (adhered) on the recording medium, and a high-quality image having excellent abrasion resistance can be obtained in a short time.

The second heating unit 80 has a heating unit 81 for heating or heat retention, and the heating unit 81 faces the surface of the roll paper 1 supported and conveyed by the medium support unit 82 to which the ink droplets are applied. It has a heater that is placed in a position where it can be used. This heater may be configured by using, for example, a heat generating resistor, and may further include a reflector for efficiently irradiating the roll paper 1 with infrared rays radiated by the heater. Further, the heater used here preferably heats the surface temperature of the recording medium to a temperature higher than the primary heating temperature in the first heating unit 70 (secondary heating temperature), preferably 50 ° C. or higher and 160 ° C. The recording medium is heated so as to be as follows. In FIG. 1, the heating unit 81 and the medium support portion 82 have the same length in the Y-axis direction, and the entire region heated by the heating unit 81 is the secondary heating region.

The above-mentioned "heating the recording medium" means raising the surface temperature of the recording medium to a desired temperature, and is not limited to directly heating the recording medium. The heating temperature of the recording medium is a temperature obtained by measuring the surface temperature of the recording medium.

In the printer 100, the length along the transport path 50 from the point where the adhesion of the ink composition to the roll paper 1 which is the recording medium is completed until the secondary drying temperature is reached is set to 500 mm or less. It is preferable to set it. This length is more preferably 400 mm or less, further preferably 300 mm or less, and particularly preferably 250 mm or less. The lower limit is not limited, but is preferably 30 mm or more, more preferably 50 mm or more, further preferably 100 mm or more, and particularly preferably 150 mm or more. By setting the length of the transport path in this way, it is possible to prevent deformation of the recording medium and provide a recording method having excellent image quality and / or abrasion resistance. It is also preferable in terms of ease of designing the transport path 50.

The length of the transport path 50 depends on the transport speed (mm / s) of the roll paper 1, but for example, the time from the completion of adhesion of the ink composition to the recording medium to the arrival of the secondary drying temperature. Can be set to a length such that can be 250 seconds or less, preferably 200 seconds or less, more preferably 150 seconds or less, still more preferably 100 seconds or less, still more preferably 60 seconds or less. It is a length that becomes.

In the printer 100, the housing 75 is configured not only to cover the entire preheating region and the primary heating region, but also to cover between the primary heating region and the secondary heating region. Therefore, it functions as a heat insulating means for keeping the surface temperature of the roll paper 1 conveyed from the primary heating region to the secondary heating region so as not to drop. Further, in order to keep the surface temperature of the roll paper 1 transported from the primary heating region to the secondary heating region constant, in addition to the heaters provided in each of the heating portions, an ink composition adhesion step is performed. The roll paper 1 which is the recording medium may be provided with a heating means for heating the roll paper 1 before the secondary drying. Further, the length of the heating unit 81 of the second heating unit 80 may be set to be long so that the distance between the primary heating region and the secondary heating region may be shortened, or the primary heating region and the secondary heating region may be shortened. A hood may be provided between the two.

Further, in the present embodiment, the printer 100 may be configured to further include a fan (not shown) downstream of the second heating unit 80, for example. This fan is for more efficiently drying the ink composition adhering to the roll paper 1 which is a recording medium after the ink composition is dried by the heater. Further, by cooling the ink composition with a fan, a film can be formed on the roll paper 1 which is a recording medium with good adhesion.

2. Ink Composition In the ink composition used in the recording method according to the present embodiment, the ink composition is a water-based ink composition containing a coloring material, water, a resin, and a water-soluble organic solvent, or is combined with a coloring material. It is a solvent-based ink composition containing an organic solvent. Hereinafter, the ink composition used in the recording method according to the present embodiment will be described.

2.1. Water-based ink composition The water-based ink composition used as the ink composition in the recording method according to the present embodiment contains a coloring material, water, a resin, and a water-soluble organic solvent. The water-based ink composition in the present embodiment is a composition containing water as a main solvent.

2.1.1. Coloring material Examples of the coloring material contained in the water-based ink composition according to the present embodiment include dyes and pigments, and pigments are used because they have a property of being resistant to fading to light, gas, etc. Is preferable. Therefore, an image formed on a recording medium such as plastic using a pigment is excellent in water resistance, gas resistance, light resistance, and the like, and has good storage stability.

The pigments that can be used in this embodiment are not particularly limited, and examples thereof include inorganic pigments and organic pigments. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. On the other hand, organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.) and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinofuralone pigments, etc.). , Nitro pigments, nitroso pigments, aniline black and the like can be used.

Among the specific examples of the pigments that can be used in the present embodiment, carbon black includes furnace black, lamp black, acetylene black, channel black, etc. (CI Pigment Black 7), and commercially available No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA77, MA100, No. 2200B etc. (all product names above, manufactured by Mitsubishi Chemical Co., Ltd.), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pretex 35, U, V, 140U, Special Black 6, 5, 4A 4,250, etc. (all product names, manufactured by Degussa), Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, etc. (all product names, manufactured by Columbia Carbon), Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12 and the like (all of the above are trade names, manufactured by Cabot Corporation).

Examples of the pigment used in the yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 180, 185, 213 and the like can be mentioned.

Examples of the pigment used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 12
3,168,184,202,209, C.I. I. Pigment Violet 19 and the like.

Examples of the pigment used for the cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15: 3, 15: 4, 16, 22, 60 and the like.

Examples of the pigment used in the green ink include C.I. I. Pigment Greens 7, 8, 36 and the like.

Examples of the pigment used for the orange ink include C.I. I. Pigment Orange 43, 51, 66 and the like.

Examples of pigments used for inks of colors other than the above, such as green ink and orange ink, include conventionally known pigments. The pigment may be used alone or in combination of two or more.

The content of the coloring material is preferably 1.0% by mass or more and 20% by mass or less, and 1.5% by mass or more and 10% by mass or less, based on the total mass (100% by mass) of the ink. More preferably, it is more preferably 2% by mass or more and 7% by mass or less.

When a pigment is used as a coloring material, it is preferable that the pigment can be stably dispersed and held in water. As the method, a method of dispersing with a resin dispersant such as a water-soluble resin and / or a water-dispersible resin (hereinafter, the pigment treated by this method may be referred to as a "resin-dispersed pigment"), a dispersant. (Hereinafter, the pigment treated by this method is sometimes referred to as "dispersant-dispersed pigment"), and a hydrophilic functional group is chemically and physically introduced into the surface of the pigment particles to form the above-mentioned resin. Alternatively, a method of making it dispersible and / or soluble in water without a dispersant (hereinafter, a pigment treated by this method may be referred to as a "surface-treated pigment") and the like can be mentioned.

In the present embodiment, any of the above-mentioned resin dispersion pigment, dispersant dispersion pigment, and surface treatment pigment can be used as the ink composition, and if necessary, a plurality of types can be mixed and used, but the resin dispersion can be used. It preferably contains a pigment.

Resin dispersants used in resin dispersion pigments include polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylic nitrile copolymers, vinyl acetate-acrylic acid ester copolymers, acrylic acid-acrylic acid ester copolymers, and 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 ester copolymer weight Examples thereof include coalescence, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer and the like, 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 composed of a monomer having both a hydrophobic functional group and a hydrophilic functional group are 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 above salts include bases such as ammonia, ethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolamine, triethanolamine, tri-iso-propanolamine, aminomethylpropanol and morpholine. Examples include salts with sex compounds. The amount of these basic compounds added is not particularly limited as long as it is equal to or greater than the neutralization equivalent of the resin dispersant.

The molecular weight of the resin dispersant is preferably in the range of 1,000 to 100,000, more preferably in the range of 3,000 to 10,000 as the weight average molecular weight. When the molecular weight is in the above range, stable dispersion of the colorant in water can be obtained, and it is easy to control the viscosity when applied to the ink composition.

Commercially available products can also be used as the resin dispersant described above. Specifically, John Krill 67 (weight average molecular weight: 12,500, acid value: 213), John Krill 678 (weight average molecular weight: 8,500, acid value: 215), John Krill 586 (weight average molecular weight: 4,600). , Acid value: 108), John krill 611 (weight average molecular weight: 8,100, acid value: 53), John krill 680 (weight average molecular weight: 4,900, acid value: 215), John krill 682 (weight average molecular weight) : 1,700, acid value: 238), John Krill 683 (weight average molecular weight: 8,000, acid value: 160), John Krill 690 (weight average molecular weight: 16,500, acid value: 240) (trade names above) , Made by BASF Japan Co., Ltd.) and the like.

The surfactants used in the surfactant dispersion pigments include alkane sulfonate, α-olefin sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, acylmethyltaurate, and dialkylsulfocarbonate. , Alkyl sulphate ester salt, sulfated olefin, polyoxyethylene alkyl ether sulphate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphoric acid ester salt, monoglycerite phosphate ester salt and other anionic surfactants, Amphoteric surfactants such as alkylpyridium salts, alkylamino acid salts, alkyldimethylbetaines, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl amides, glycerin alkyl esters, sorbitan alkyl Examples thereof include nonionic surfactants such as esters.

The amount of the resin dispersant or the surfactant added to the pigment is preferably 1 part by mass or more and 100 parts by mass or less, and more preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the pigment. .. Within this range, the dispersion stability of the pigment in water can be ensured.

The surface treatment pigments include -OM, -COOM, -CO- _{, -SO 3} M, -SO ₂ NH ₃ , -RSO ₃ M, -PO ₃ HM, and -PO ₃ M _{3 as hydrophilic functional groups.} , -SO ₃ NHCOR, -NH ₃ , -NR ₃ (where M in the formula represents a hydrogen atom, alkali metal, ammonium or organic ammonium, and R represents an alkyl group or substituent having 1 to 12 carbon atoms. (Indicates a phenyl group which may have a phenyl group or a naphthyl group which may have a substituent) and the like. These functional groups are physically and / or chemically introduced by being grafted directly and / or via other groups on the surface of the pigment particles. Examples of the polyvalent group include an alkylene group having 1 to 12 carbon atoms, a phenylene group which may have a substituent, a naphthylene group which may have a substituent, and the like.

_{Further, as the surface treatment pigment, -SO 3} M and / or -RSO ₃ M (M is a counter ion, hydrogen ion, alkali metal ion, ammonium ion) on the surface of the pigment particle by a treatment agent containing sulfur. , Or organic ammonium ions) are surface-treated so as to chemically bond, that is, the pigment does not have an active proton, does not have reactivity with sulfonic acid, and the pigment is insoluble or sparingly soluble. The pigment is dispersed in a solvent that is, and then _{surface-treated with amidosulfate or a complex of sulfur trioxide and a tertiary amine so that -SO 3} M and / or -RSO ₃ M are chemically bonded to the particle surface. It is preferable that the particles are capable of being dispersed and / or dissolved in water.

Various known surface treatment means can be applied as the surface treatment means for grafting the functional group or a salt thereof onto the surface of the pigment particles directly or via a polyvalent group. For example, a means for allowing ozone or a sodium hypochlorite solution to act on commercially available carbon oxide black to further oxidize the carbon black to make the surface more hydrophilic (for example, JP-A-7-258578, JP-A-P.). 8-3498, 10-120958, 10-195331, 10-237349), means for treating carbon black with 3-amino-N-alkyl-substituted pyridium bromide (Japanese Patent Laid-Open No. 8-3498, JP-A-10-195331, JP-A-10-237349) For example, Japanese Patent Application Laid-Open No. 10-195360, Japanese Patent Application Laid-Open No. 10-330665) disperse an organic pigment in a solvent in which the organic pigment is insoluble or sparingly soluble, and introduce a sulfone group onto the surface of the pigment particles by a sulfonizing agent. Means (for example, JP-A-8-283596, JP-A-10-110110, JP-A-10-110111), organic pigments are dispersed in a basic solvent that forms a complex with sulfur trioxide, and trioxidation is performed. Examples thereof include means for treating the surface of an organic pigment by adding sulfur to introduce a sulfone group or a sulfone amino group (for example, Japanese Patent Application Laid-Open No. 10-110114). The manufacturing means for this is not limited to these means.

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

As a method for dispersing the resin-dispersed pigment, the surfactant-dispersed pigment, and the surface-treated pigment in water as described above, the resin-dispersed pigment is a pigment and water and a resin dispersant, and the surfactant-dispersed pigment is a pigment and water and an interface. For activators and surface treatment pigments, add surface treatment pigments and water, and if necessary, water-soluble organic solvents and neutralizers, etc., to ball mills, sand mills, attritors, roll mills, agitator mills, henshell mixers, colloids. This can be performed with a conventionally used disperser such as a mill, an ultrasonic homogenizer, a jet mill, or an ong mill. In this case, the particle size of the pigment is dispersed until the average particle size is in the range of 20 nm to 500 nm, more preferably in the range of 50 nm to 200 nm, thereby ensuring the dispersion stability of the pigment in water. It is preferable in that respect.

2.1.2. Water In this embodiment, the water-based ink composition contains water. Water is the main medium of the ink composition and is a component that evaporates and scatters due to drying. The water is preferably water from which ionic impurities such as pure water or ultrapure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water have been removed as much as possible. Further, it is preferable to use water sterilized by ultraviolet irradiation or addition of hydrogen peroxide because the growth of mold and bacteria can be suppressed when the water-based ink composition is stored for a long period of time.

The content of water is 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more, based on the total amount of the water-based ink composition. When the water content is 40% by mass or more, the water-based ink composition can have a relatively low viscosity. The upper limit of the water content is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less with respect to the total amount of the water-based ink composition.

2.1.3. Resin In this embodiment, the water-based ink composition contains a water-soluble and / or water-insoluble resin component. The resin component has an effect of solidifying the ink and firmly fixing the solidified ink on the recording medium. The resin may be in either a state of being dissolved in the water-based ink composition or a state of being dispersed in the water-based ink composition. As the resin in the dissolved state, the above-mentioned resin dispersant used when the pigment of the water-based ink composition used in the present embodiment is dispersed can be used. Further, as the dispersed resin, a resin that is poorly soluble or insoluble in the liquid medium of the ink composition used in the present embodiment is dispersed in the form of fine particles (that is, in an emulsion state or a suspension state). Can be made.

Examples of the above-mentioned resin include, in addition to the resin used as the above-mentioned resin dispersant, polyacrylic acid ester or a copolymer thereof, polymethacrylic acid ester or a copolymer thereof, polyacrylonitrile or a copolymer thereof, polycyanoacrylate, and the like. Polyacrylamide, polyacrylic acid, polymethacrylic acid, polyethylene, polypropylene, polybutene, polyisobutylene, polystyrene or a polymer thereof, petroleum resin, chroman-inden resin, terpene resin, polyvinyl acetate or a copolymer thereof, polyvinyl alcohol , Polyvinyl acetal, polyvinyl ether, polyvinyl chloride or a copolymer thereof, polyvinylidene chloride, fluororesin, fluororubber, polyvinylcarbazole, polyvinylpyrrolidone or a copolymer thereof, polyvinylpyridine, polyvinylimidazole, polybutadiene or a copolymer thereof, Examples thereof include polychloroprene, polyisoprene, and natural resins. Among these, those having both a hydrophobic portion and a hydrophilic portion in the molecular structure are particularly preferable.

In order to obtain the above resin in a fine particle state, it can be obtained by the method shown below, any of the methods may be used, and a plurality of methods may be combined as necessary. The method includes a method of mixing a polymerization catalyst (polymerization initiator) and a dispersant in a monomer constituting a desired resin and polymerizing (that is, emulsion polymerization), and a resin having a hydrophilic portion is a water-soluble organic substance. Obtained by dissolving in a solvent, mixing the solution in water, and then removing the water-soluble organic solvent by distillation or the like, or dissolving the resin in a water-insoluble organic solvent and mixing the solution with a dispersant in an aqueous solution. The method and the like can be mentioned. The above method can be appropriately selected according to the type and characteristics of the resin to be used. The dispersant that can be used when dispersing the resin is not particularly limited, but is an anionic surfactant (for example, sodium dodecylbenzene sulfonic acid salt, sodium lauryl phosphate salt, polyoxyethylene alkyl ether sulfate ammonium salt). Etc.), nonionic surfactants (eg, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl phenyl ethers, etc.), and these may be used alone or in combination of two. The above can be mixed and used.

When the resin as described above is used in a fine particle state (emulsion form, suspension form), it is also possible to use a resin obtained by a known material and method. For example, those described in Japanese Patent Application Laid-Open No. 62-1426, Japanese Patent Application Laid-Open No. 3-56573, Japanese Patent Application Laid-Open No. 3-79678, Japanese Patent Application Laid-Open No. 3-160068, Japanese Patent Application Laid-Open No. 4-18462, etc. may be used. good. Commercially available products can also be used, for example, Microgel E-1002, Microgel E-5002 (trade name, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001, Boncoat 5454 (trade name, Dainippon Ink and Chemicals). SAE1014 (trade name, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (trade name, manufactured by Saiden Chemical Co., Ltd.), John Krill 7100, John Krill 390, John Krill 711, John Krill 511, John Krill 7001, John Krill 632, John Krill 741, John Krill 450, John Krill 840, John Krill 74J, John Krill HRC-1645J, John Krill 734, John Krill 852, John Krill 7600, John Krill 775, John Krill 537J, John Krill 1535, John Krill PDX-7630A, John Krill 352J, John Krill 352D, John Krill PDX-7145, John Krill 538J, John Krill 7640, John Krill 7641, John Krill 6
31, John Krill 790, John Krill 780, John Krill 7610 (trade name, manufactured by BASF Japan Ltd.) and the like can be mentioned.

When the resin is used in the fine particle state, the average particle size is preferably in the range of 5 nm to 400 nm, more preferably in the range of 50 nm to 200 nm, from the viewpoint of ensuring the storage stability and ejection stability of the ink composition.

The glass transition temperature (Tg) of the resin is, for example, preferably −20 ° C. or higher and 100 ° C. or lower, and more preferably −10 ° C. or higher and 80 ° C. or lower.

The content of the resin is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less in terms of solid content, based on the total amount of the ink composition. Within this range, the ink composition used in the inkjet recording method according to the present embodiment can be solidified and fixed even on plastic media.

2.1.4. Water-soluble organic solvent The water-based ink composition according to this embodiment contains a water-soluble organic solvent. The water-soluble organic solvent has functions such as improving the adhesion of the ink to the non-absorbent recording medium and suppressing the drying of the head of the inkjet recording device.

The water-soluble organic solvent is not particularly limited, and examples thereof include 1,2-alkanediols, polyhydric alcohols (excluding 1,2-alkanediols), pyrrolidone derivatives, glycol ethers and the like. Further, examples of the water-soluble organic solvent include alkanediols and polyols.

Examples of 1,2-alkanediols include 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol and the like. .. The 1,2-alkanediols are excellent in the action of enhancing the wettability of the water-based ink composition with respect to the recording medium and uniformly wetting the ink composition. When 1,2-alkanediols are contained, the content thereof can be 1% by mass or more and 20% by mass or less with respect to the total mass of the water-based ink composition.

Examples of polyhydric alcohols (excluding 1,2-alkanediols) include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6. -Hexanediol, trimethylolpropane, glycerin and the like can be mentioned. When it contains polyhydric alcohols, it can be 1% by mass or more and 20% by mass or less with respect to the total mass of the water-based ink composition.

Examples of the pyrrolidone derivative include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, and 5-methyl-2-pyrrolidone. And so on. Pyrrolidone derivatives act as good solubilizers for resins. When the pyrrolidone derivative is contained, it can be 1% by mass or more and 30% by mass or less with respect to the total mass of the water-based ink composition.

Examples of glycol ethers include ethylene glycol monoisobutyl ether, ethylene glycol monoisohexyl ether, ethylene glycol monoisohexyl ether, diethylene glycol monohexyl ether, triethylene glycol monohexyl ether, diethylene glycol monoisohexyl ether, and triethylene glycol monoiso. Hexyl ether, ethylene glycol monoisoheptyl ether, diethylene glycol monoisoheptyl ether, triethylene glycol monoisoheptyl ether, ethylene glycol monooctyl ether, ethylene glycol monoisooctyl ether, diethylene glycol monoisooctyl ether, triethylene glycol monoisooctyl ether , Ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, triethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono -2-Ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol mono-2-methylpentyl ether, diethylene glycol mono-2-methylpentyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, Examples thereof include propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, and tripropylene glycol monomethyl ether. These can be used alone or in admixture of two or more. Glycol ethers can control the wettability of the water-based ink composition with respect to the recording medium.

Examples of the alkane diols include alkane diols having 5 or more carbon atoms, and the number of carbon atoms of the alkane is not limited, but is preferably 10 or less, and more preferably 9 or less. Examples of the alkanediols include, for example, the above-mentioned 1,2-alkanediols, but are not limited to 1,2-substituted products. Alkanediols are excellent in the action of enhancing the wettability of the water-based ink composition with respect to the recording medium and uniformly wetting it. When the water-based ink composition contains alkanediols, the content thereof can be 1% by mass or more and 20% by mass or less with respect to the total mass of the water-based ink composition.

Examples of the polyols include diols of alkanes having 4 or less carbon atoms, condensates of diols of alkanes having 4 or less carbon atoms, and polyols having a trivalent or higher valence of alkanes. Examples of the polyols include the above-mentioned polyhydric alcohols, but may include 1,2-alkanediols that are alkanediols having 4 or less carbon atoms. The polyols are excellent in the action of preventing the ink in the nozzle from drying out. When the water-based ink composition contains polyols, it can be 1% by mass or more and 20% by mass or less with respect to the total mass of the water-based ink composition.

The content of the water-soluble organic solvent is not particularly limited, but can be, for example, 1% by mass or more and 40% by mass or less with respect to the total mass of the water-based ink composition, and the lower limit is 3% by mass. The above is preferable, 5% by mass or more is more preferable, 10% by mass or more is further preferable, 20% by mass or more is further preferable, 25% by mass or more is particularly preferable, and 30% by mass or more is even more preferable. The upper limit of the content of the water-soluble organic solvent is preferably 35% by mass or less.

The water-based ink composition preferably contains a water-soluble organic solvent having a standard boiling point of 150 ° C. or higher and 280 ° C. or lower as the water-soluble organic solvent. Further, the content of the water-soluble organic solvent having a standard boiling point of more than 280 ° C. is preferably 3% by mass or less. In this case, since the water-based ink composition has good drying property, the stickiness of the recorded material obtained in the recording step is reduced, and the obtained recorded material has excellent scratch resistance.

As the water-soluble organic solvent which is a water-soluble organic solvent having a standard boiling point of 150 ° C. or higher and 280 ° C. or lower, at least one water-soluble organic solvent of alkanediol and alkylene glycol monoether derivative is preferably used. The standard boiling point of the water-soluble organic solvent is preferably 250 ° C. or lower, more preferably 230 ° C. or lower. The content of the water-soluble organic solvent having a standard boiling point of 250 ° C. or lower is more preferably 20% by mass or more, further preferably 25% by mass or more, and further preferably 30% by mass or more. preferable.

An organic solvent having a standard boiling point of more than 280 ° C. may absorb water in the ink composition and thicken the ink composition in the vicinity of the inkjet head. This may reduce the ejection stability of the inkjet head.

Examples of the water-soluble organic solvent having a boiling point of more than 280 ° C. include glycerin. If the water-based ink composition is added with a high boiling point organic solvent having high hygroscopicity such as glycerin, it may cause clogging of the head or malfunction of the cap device. In addition, glycerin is preferably not contained in the ink composition because it has poor antiseptic properties and easily propagates molds and fungi.

Therefore, in the present embodiment, the content of the water-soluble organic solvent having a standard boiling point of more than 280 ° C. in the water-based ink composition is more preferably 2% by mass or less, further preferably 1% by mass or less. It is more preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less, and particularly preferably 0.05% by mass or less.

2.1.5. Surfactant In this embodiment, the water-based ink composition may contain a surfactant. The surfactant has a function of improving the wettability with a recording medium by reducing the surface tension of the ink. Among the surfactants, for example, acetylene glycol-based surfactants, silicon-based surfactants, fluorine-based surfactants and the like can be preferably used.

The acetylene glycol-based surfactant is not particularly limited, but for example, Surfinol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE- F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D, Orfin B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003 , PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all product names above, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all product names above, all product names, Kawaken Fine Chemical Co., Ltd.).

The silicon-based surfactant is not particularly limited, but a polysiloxane-based compound is preferably mentioned. The polysiloxane-based compound is not particularly limited, and examples thereof include polyether-modified organosiloxane. Examples of commercially available products of the polyether-modified organosiloxane include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, and BYK-348 (trade names, manufactured by BYK). , KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515 , KF-6011, KF-6012, KF-6015, KF-6017 (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples thereof include BYK-340 (manufactured by Big Chemie Japan).

When a surfactant is contained, the content thereof can be 0.1% by mass or more and 2.5% by mass or less with respect to the total mass of the water-based ink composition.

2.1.6. Other Ingredients In the present embodiment, the water-based ink composition may further contain a pH adjuster, a polyolefin wax, a preservative / antifungal agent, a rust preventive, a chelating agent, and the like. The addition of these materials can further improve the properties of the ink composition.

Examples of the pH adjuster include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, and sodium carbonate. Examples include sodium hydrogen carbonate and the like.

Examples of the polyolefin wax include waxes produced from olefins such as ethylene, propylene and butylene or derivatives thereof and copolymers thereof, specifically, polyethylene wax, polypropylene wax, polybutylene wax and the like. As the polyolefin wax, commercially available ones can be used. Specifically, Nopcoat PEM17 (trade name, manufactured by San Nopco Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals Co., Ltd.), AQUACER515, AQUACER593. (The above product name, manufactured by Big Chemie Japan Co., Ltd.) can be used.

The addition of the polyolefin wax is preferable from the viewpoint that the slipperiness of the image formed on the non-ink-absorbing or low-absorbing recording medium to physical contact can be improved and the scratch resistance of the image can be improved. The content of the polyolefin wax is preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.05% by mass or more and 1% by mass or less, based on the total mass of the ink composition. When the content of the polyolefin wax is in the above range, the above-mentioned effects are fully exhibited.

Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, and 1,2-dibenzisothiazolin-3-one. And so on. Examples of commercially available products include Proxel XL2 and Proxel GXL (trade name, manufactured by Abyssia), Deniside CSA, NS-500W (trade name, manufactured by Nagase ChemteX Corporation) and the like.

Examples of the rust preventive include benzotriazole and the like.

Examples of the chelating agent include ethylenediaminetetraacetic acid and salts thereof (ethylenediaminetetraacetic acid dihydrogen disodium salt and the like).

2.1.7. Physical Properties of Water-based Ink Composition The water-based ink composition used in this embodiment has a surface tension of 20 mN / m or more and 40 mN / m at 20 ° C. from the viewpoint of balancing image quality and reliability as an ink for inkjet recording. It is preferably 20 mN / m or more and 35 mN / m or less. The surface tension is measured by, for example, using an automatic tensiometer CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) to measure the surface tension when the platinum plate is wetted with ink in an environment of 20 ° C. It can be measured by checking.

From the same viewpoint, the viscosity of the water-based ink composition used in the present embodiment at 20 ° C. is preferably 3 mPa · s or more and 10 mPa · s or less, and preferably 3 mPa · s or more and 8 mPa · s or less. More preferred. The viscosity can be measured by using, for example, a viscoelasticity tester MCR-300 (trade name, manufactured by Pysica) in an environment of 20 ° C.

2.2. Solvent-based ink composition The solvent-based ink composition used in the recording method according to the present embodiment contains a coloring material and an organic solvent.

The solvent-based ink composition in the present embodiment is a composition in which an organic solvent or the like is used as a main solvent and water is not used as a main solvent. The content of water in the composition is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, based on 100% by mass of the composition. 5% by mass or less is particularly preferable. The content of the organic solvent or the like in the ink composition (100% by mass) is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. Further, although not limited, the composition may be an acceptable composition when water is not intentionally added as a main solvent component in the preparation of the composition and water is inevitably contained as an impurity.

2.2.1. Coloring Material The solvent-based ink composition used in this embodiment contains a coloring material. As the coloring material, pigments or dyes such as inorganic pigments or organic pigments usually used for conventional solvent-based inks can be used alone or in combination. Examples of organic pigments include azo pigments (for example, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxandine pigments, etc. Examples thereof include thioindigo pigments, isoindolinone pigments, quinophthaloni pigments, etc.), dye lakes (for example, basic dye type lakes, acidic dye type lakes, etc.), nitro pigments, nitroso pigments, aniline blacks, daylight fluorescent pigments, and the like. Examples of the inorganic pigment include carbon black, titanium dioxide, silica, and alumina. Examples of dyes include azo dyes, metal complex salt dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthin dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone millet, and phthalocyanine. Dyes or metallic phthalocyanine dyes can be used, with oil-soluble dyes being particularly preferred. These pigments or dyes can be used alone or in combination of two or more thereof, but pigments are preferable from the viewpoint of weather resistance. The volume average particle size of the pigment primary particles is 50 to 500 nm, preferably 50 to 200 nm.

The content of the coloring material can be appropriately set as desired and is not particularly limited, but is usually 0.1% by mass or more and 10% by mass or less with respect to the total mass of the ink composition, which is preferable. Is 0.5% by mass or more and 8% by mass or less, more preferably 1% by mass or more and 6% by mass or less. When the content of the coloring material is in the above range, the color developing property is excellent, and the image formed by this ink composition has good weather resistance.

When a pigment is used as the coloring material, a pigment dispersant may be contained, and an arbitrary dispersant used in ordinary solvent-based inks, particularly solvent-based inks for inkjet recording, should be used. Can be done.

As the dispersant, it is preferable to use a dispersant that works effectively when the solubility parameter of the organic solvent is 8 to 11. Commercially available products can be used as such dispersants, and specific examples thereof include Hinoact KF1-M, T-6000, T-7000, T-8000, T-8350P, and T-8000E (the above products). Name, polyester polymer compound such as Takefu Fine Chemical Co., Ltd.), Solspers 20000, 24000, 32000, 32500, 33500, 34000, 35200, 37500 (trade name, manufactured by LUBRIZOL), Disperbyk-161, 162, 163, 164, 166, 180, 190, 191, 192, 2091, 2095 (trade name, manufactured by Big Chemie Japan), Floren DOPA-17, 22, 33, G-700 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.) , Azisper PB821, PB711 (trade name, manufactured by Ajinomoto Co., Ltd.), LP4010, LP4050, LP4055, POLYMER400, 401, 402, 403, 450, 451 and 453 (trade name, manufactured by EFKA Chemicals Co., Ltd.) and the like. The content of the pigment dispersant when used can be appropriately selected depending on the pigment contained in the ink composition, but is preferably 5 parts by mass or more and 200 parts by mass with respect to 100 parts by mass of the pigment content in the ink composition. It is less than or equal to parts by mass, more preferably 30 parts by mass or more and 120 parts by mass or less.

2.2.2. Organic Solvent The solvent-based ink composition used in this embodiment contains an organic solvent. The organic solvent is not particularly limited, and examples thereof include an alkylene glycol monoether-based solvent, an alkylene glycol diether-based solvent, and a lactone (cyclic ester).

<alkylene glycol monoether solvent>
The alkylene glycol monoether-based solvent preferably contains a compound represented by the following general formula (1).
R ¹ O- (R ² O) _m- OH ... (1)
(In the general formula (1), R ¹ represents an alkyl group having 1 or more carbon atoms and 4 or less ^{carbon atoms. R 2} represents an alkylene group having 2 or more carbon atoms and 4 or less carbon atoms. M represents an integer of 1 to 7.)

Here, the "alkyl group having 1 to 4 carbon atoms" of R ^1, can be straight-chain or branched alkyl group, e.g., methyl group, ethyl group, n- propyl group, iso- Examples thereof include a propyl group, an n-butyl group, a sec-butyl group, an isobutyl group and a tert-butyl group.

Further, in the above general formula (1) ^{, examples of the "alkylene group having 2 or more and 4 or less carbon atoms" in R 2} include an ethylene group, an n-propylene group, an isopropylene group, a butylene group and the like. Further, in the above general formula (1), ^{it is preferable that R 1} has a large number of carbon atoms and m in terms of reducing damage to the member, and m is preferably an integer of 3 to 6.

Specific examples of the solvent which is the compound represented by the above general formula (1) include, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and diethylene glycol mono. Ethylene ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, pentaethylene glycol monomethyl ether , Pentaethylene glycol monoethyl ether, pentaethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether and the like. These compounds can be used alone or in admixture of two or more.

<alkylene glycol diether solvent>
Examples of the alkylene glycol diether-based solvent include compounds represented by the following general formula (2).
R ³ O- (R ⁴ O) _n- R ⁵ ... (2)
(In the general formula (2), R ³ and R ⁵ each independently represent an alkyl group having 1 or more carbon atoms and 4 or less ^{carbon atoms. R 4} represents an alkylene group having 2 or more carbon atoms and 4 or less carbon atoms. Represents an integer of 7.)

Here, the ^{"alkyl group having 1 or more and 4 or less carbon atoms" in R 3} and R ⁵ can be a linear or branched alkyl group, for example, a methyl group, an ethyl group, or an n-propyl group. , Iso-propyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group and the like.

In the general formula (2), as the "alkylene group having 2 to 4 carbon atoms" in R ^4, for example, ethylene, n- propylene, isopropylene or butylene group and the like. Further, in the above general formula (2), ^{it is preferable that R 3} and R ⁵ have a large number of carbon atoms and n in terms of reducing damage to the member, and n is preferably an integer of 3 to 6.

Specific examples of the solvent which is the compound represented by the above general formula (2) include, for example, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, and diethylene glycol di. Butyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol Examples thereof include dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether. The alkylene glycol diethers can be used alone or in admixture of two or more.

The content of the alkylene glycol ether-based solvent is preferably 80% by mass or less, more preferably 30% by mass or more and 75% by mass or less, still more preferably 40% by mass, based on the total mass of the solvent-based ink composition. It is mass% or more and 70 mass% or less.

<Lactone (cyclic ester)>
The solvent-based ink composition used in this embodiment may contain a lactone (cyclic ester) as an organic solvent. When the solvent-based ink composition contains lactone, a part of the recording surface of the recording medium (for example, the recording surface containing a vinyl chloride resin) can be dissolved and the ink composition can be permeated into the recording medium. .. By penetrating the ink into the recording medium in this way, the abrasion resistance (friction fastness) of the image recorded on the recording medium can be improved. In other words, since the lactone has a high affinity with the vinyl chloride resin, the components of the solvent-based ink composition are easily infiltrated into the recording surface (easily bitten). As a result of the lactone having such an action, it is considered that the ink composition containing the lactone can form an image having excellent abrasion resistance even under severe conditions such as an outdoor environment.

The lactone is a compound having a structure in which the hydroxyl group and the carboxyl group are dehydrated and condensed in one molecule having a hydroxyl group and a carboxyl group. The cyclic ester is a compound having a heterocycle containing two or more carbon atoms and one oxygen atom, and having a structure in which a carbonyl group is arranged adjacent to the oxygen atom forming the heterocycle.

Among the lactones, those having a simple structure include β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, ε-caprolactone and the like. Can be done. The number of ring members of the heterocycle of the lactone is not particularly limited, and for example, any side chain may be bonded to the ring member of the heterocycle. The lactone may be used alone or in combination of two or more.

From the viewpoint of further enhancing the scratch resistance of the image formed by the solvent-based ink composition used in the present embodiment, among the above-exemplified lactones, lactones having a 3-membered ring or more and a 7-membered ring or less are preferable, and a 5-membered ring. Alternatively, it is more preferable to use a 6-membered ring lactone, and in any case, it is more preferable to have no side chain. Specific examples of such lactones include β-butyrolactone, γ-butyrolactone, and γ-valerolactone. Further, since such a lactone has a particularly high affinity with polyvinyl chloride, the effect of enhancing the abrasion resistance can be extremely remarkably obtained when it is attached to a recording medium containing polyvinyl chloride. ..

When the lactone is blended, the content of the solvent-based ink composition with respect to the total amount (the total amount when a plurality of types are used) is 5% by mass or more and 50% by mass or less, preferably 7% by mass or more and 30%. It is 10% by mass or less, more preferably 10% by mass or more and 20% by mass or less.

<Other organic solvents>
The ink composition used in the present embodiment may further contain the organic solvent exemplified below in addition to the organic solvent exemplified above.

Such organic solvents are preferably polar organic solvents such as alcohols (methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, fluoroalcohol, etc.) and ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.). , Carboxylates (methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, etc.), ethers (diethyl ether, dipropyl ether, tetrahydrofuran, dioxane, etc.), polyhydric alcohols (ethylene) Glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane, etc.) Be done.

Moreover, (polyhydric) alcohols may be contained as an organic solvent. Examples of (polyvalent) alcohols include glycerin, propylene glycol, dipropylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptandiol, and 3-methyl-. 1,3-Butanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2, Examples thereof include 2-dimethyl-1,3-propanediol and 2-methylpentane-2,4-diol.

In addition, amines may be blended in the solvent-based ink composition, for example, triethanolamine, tripropanolamine, tributanolamine, N, N-dimethyl-2-aminoethanol, N, N-diethyl-2. -Hydramines such as aminoethanol can be mentioned, and one or more kinds can be used.

Further, as an organic solvent, higher fatty acid esters such as methyl laurate, isopropyl hexadecanoate (isopropyl palmitate), isopropyl myristate, methyl oleate, ethyl oleate, and dicarboxylic acids of aliphatic hydrocarbons having 2 to 8 carbon atoms (dicarboxylic acids). A dibasic acid diester obtained by diestering an alkyl group having 1 to 5 carbon atoms (excluding the carbon of the carboxyl group) and a monocarboxylic acid of an aliphatic hydrocarbon having 6 to 10 carbon atoms (the carbon number is a carboxyl group). Alkamide (N, N-dimethyldecaneamide, etc.) in which the amidated (excluding the carbon of) is an amidated (the substituents substituting the amide nitrogen atom are independently hydrogen atoms and alkyl groups having 1 to 4 carbon atoms). ) Etc. can be mentioned.

For the other organic solvents exemplified here, one or more kinds are added to the solvent-based ink composition in an appropriate blending amount, and the total content of the solvent is 80 mass by mass with respect to the total mass of the ink composition. It can be added so as to be% or more. For example, the content of these solvents is preferably 0.05% by mass or more and 5% by mass or less, and 0.1% by mass or more and 3% by mass or less, based on the total mass of the solvent-based ink composition. Is even more preferable.

As the other organic solvents exemplified here, one or more kinds can be added to the solvent-based ink composition in an appropriate blending amount.

2.2.3. Fixing Resin The solvent-based ink composition used in the present embodiment may contain a fixing resin for fixing the above-mentioned coloring material on a recording medium.

Examples of the fixing resin include acrylic resin, styrene acrylic resin, rosin-modified resin, phenol resin, terpene resin, polyester resin, polyamide resin, epoxy resin, vinyl acetate resin, vinyl chloride resin, fiber-based resin such as cellulose acetate butyrate, and vinyl. Examples thereof include toluene-α-methylstyrene copolymer resin. Among these, at least one resin selected from the group consisting of acrylic resin and vinyl chloride resin is preferable, and vinyl chloride resin is more preferable. By containing these fixing resins, the fixability to the recording medium can be improved, and the abrasion resistance is also improved.

The solid content of the fixing resin in the solvent-based ink composition used in the present embodiment is preferably 0.05% by mass or more and 15% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and further. It is preferably 1% by mass or more and 5% by mass or less. When the content of the fixing resin is within the above range, excellent fixability to the recording medium can be obtained.

<Acrylic resin>
Examples of the acrylic resin include poly (meth) acrylic acid, methyl poly (meth) acrylic acid, ethyl poly (meth) acrylic acid, (meth) acrylic acid- (meth) acrylic acid ester copolymer resin, and styrene- (meth). ) Acrylic copolymer resin, ethylene- (meth) acrylic acid copolymer resin, ethylenealkyl (meth) acrylate resin, ethylene- (meth) acrylic acid ester copolymer resin and other (meth) acrylic monomers, or others. Examples thereof include a copolymer resin with the above-mentioned monomer. These can be used alone or in combination of two or more.

As the above-mentioned acrylic resin, a commercially available product may be used, for example, Acrypet MF (trade name, manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin), Sumipex LG (trade name, manufactured by Sumitomo Chemical Co., Ltd., acrylic resin), Pararoid B. Examples include a series (trade name, manufactured by Rohm and Haas, acrylic resin), Parapet G-1000P (trade name, manufactured by Kuraray, acrylic resin) and the like. In the present invention, "(meth) acrylic acid" means both acrylic acid and methacrylic acid, and "(meth) acrylate" means both acrylate and methacrylate.

<Vinyl chloride resin>
Examples of the vinyl chloride resin include a copolymer of vinyl chloride and other monomers such as vinyl acetate, vinylidene chloride, acrylic acid, maleic acid, and vinyl alcohol.
Among these, a copolymer containing a structural unit derived from vinyl chloride and vinyl acetate (hereinafter, also referred to as “salt-vinegar vinyl copolymer”) is preferable, and vinyl chloride and vinyl acetate having a glass transition temperature of 60 to 80 ° C. are preferable. Polymers are more preferred.

The vinyl acetate copolymer can be obtained by a conventional method, for example, by suspension polymerization. Specifically, water, a dispersant, and a polymerization initiator are charged in a polymerizer, and after degassing, vinyl chloride and vinyl acetate are press-fitted for suspension polymerization, or a part of vinyl chloride and vinyl acetate are press-fitted. Then, the reaction can be started, and suspension polymerization can be carried out while press-fitting the remaining vinyl chloride during the reaction.

The vinyl acetate copolymer preferably contains 70 to 90% by mass of vinyl chloride units as its constitution. Within the above range, it is stably dissolved in the ink composition, so that it is excellent in long-term storage stability. Further, the ejection stability is excellent, and excellent fixability to the recording medium can be obtained.

Further, the vinyl chloride copolymer may include other structural units as necessary in addition to the vinyl chloride unit and the vinyl acetate unit, and examples thereof include a carboxylic acid unit, a vinyl alcohol unit, and a hydroxyalkyl acrylate unit. Of particular, vinyl alcohol units are preferred. It can be obtained by using the monomer corresponding to each of the above-mentioned units. Specific examples of the monomer giving a carboxylic acid unit include maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, acrylic acid, and methacrylic acid. Specific examples of the monomer giving the hydroxyalkyl acrylate unit include hydroxyethyl (meth) acrylate, hydroxyethyl vinyl ether and the like. The content of these monomers is not limited as long as the effects of the present invention are not impaired, but for example, copolymerization can be carried out in the range of 15% by mass or less of the total amount of the monomers.

Commercially available PVC copolymers may be used, for example, Solvine CN, Solvine CNL, Solvine C5R, Solvine TA5R, Solvine CL, Solvine CLL (all manufactured by Nisshin Chemical Industry Co., Ltd.). , Kaneka Vinyl HM515 (manufactured by Kaneka Corporation) and the like.

The average degree of polymerization of these resins is not particularly limited, but is preferably 150 to 1100, more preferably 200 to 750. When the average degree of polymerization of these resins is within the above range, they are stably dissolved in the solvent-based ink composition used in the present embodiment, so that they are excellent in long-term storage stability. Further, the ejection stability is excellent, and excellent fixability to the recording medium can be obtained. The average degree of polymerization of these resins is calculated by measuring the specific viscosity, and can be obtained according to the method for calculating the average degree of polymerization described in "JIS K6720-2".

The number average molecular weight of these resins is not particularly limited, but is preferably 1000 to 50000, and more preferably 12000 to 42000. The number average molecular weight can be measured by GPC and can be obtained as a relative value in terms of polystyrene.

2.2.4. Surfactant The solvent-based surfactant used in this embodiment contains a silicon-based surfactant, a fluorine-based surfactant, or a non-ionic surfactant from the viewpoint of reducing surface tension and improving wettability with a recording medium. A polyoxyethylene derivative which is a sex surfactant may be added.

As the silicon-based surfactant, it is preferable to use polyester-modified silicon or polyether-modified silicon. Specific examples include BYK-315, 315N, 347, 348, BYK-UV3500, 3510, 3530, 3570 (trade names, manufactured by Big Chemie Japan).

As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples thereof include BYK-340 (manufactured by Big Chemie Japan).

Further, as the polyoxyethylene derivative, it is preferable to use an acetylene glycol-based surfactant. Specific examples include Surfinol 82, 104, 465, 485, TG (trade name, manufactured by Air Products Japan Co., Ltd.), Orfin STG, E1010 (trade name, manufactured by Nissin Chemical Co., Ltd.), Nissan Nonion A-10R. , A-13R (trade name, manufactured by Nichiyu Co., Ltd.), Floren TG-740W, D-90 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), Neugen CX-100 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (Manufactured) and the like.

The content of the surfactant in the solvent-based ink composition used in the present embodiment is preferably 0.05% by mass or more and 3% by mass or less, more preferably 0.5% by mass or more and 2% by mass or less, still more preferably. Is 1% by mass or more and 1.5% by mass or less.

2.2.5. Other Ingredients The solvent-based ink composition used in the present embodiment includes a pH adjuster, a chelating agent such as ethylenediaminetetraacetic acid (EDTA), a preservative / antifungal agent, and a rust preventive, if necessary. Etc., a substance for imparting a predetermined performance can be added.

2.2.6. Method for Preparing Solvent-Based Ink Composition The solvent-based ink composition used in the present embodiment is obtained by mixing the above-mentioned components in an arbitrary order and, if necessary, filtering or the like to remove impurities. As a method of mixing each component, a method of sequentially adding materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring and mixing them is preferably used. As the filtration method, centrifugal filtration, filter filtration and the like can be performed as needed.

2.2.7. Physical Properties of Solvent-based Ink Composition The solvent-based ink composition used in this embodiment has a surface tension of 20 mN / m or more and 50 mN at 20 ° C. from the viewpoint of a balance between recording quality and reliability as an ink for inkjet recording. It is preferably / m, and more preferably 25 mN / m or more and 40 mN / m or less. The surface tension is measured by using an automatic tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) to check the surface tension when the platinum plate is wetted with ink in an environment of 20 ° C. can do.

From the same viewpoint, the viscosity of the solvent-based ink composition at 20 ° C. is preferably 2 mPa · s or more and 15 mPa · s or less, and more preferably 2 mPa · s or more and 10 mPa · s or less. The viscosity is measured by increasing the Shear Rate to 10 to 1000 in an environment of 20 ° C. using a viscoelasticity tester MCR-300 (manufactured by Pysica) and reading the viscosity at Shear Rate 200. Can be measured.

3. 3. Reaction solution Next, the reaction solution that can be used in the recording step described later will be described. The reaction solution used in the present embodiment contains a coagulant and other components that agglutinate the components of the water-based ink composition among the ink compositions, and forms a higher image quality image by the agglutinating action of the coagulant. can do.

3.1. Coagulant The reaction solution used in this embodiment contains a coagulant that coagulates the components of the ink composition. When the reaction solution contains a coagulant, the coagulant and the resin contained in the ink composition react rapidly in the recording step described later. Then, the dispersed state of the coloring material and the resin in the ink composition is destroyed, and the coloring material and the resin are aggregated. Then, since this agglutinating substance hinders the penetration of the coloring material into the recording medium, it is considered to be excellent in terms of improving the image quality of the recorded image.

Examples of the flocculant include polyvalent metal salts, cationic compounds (cationic resins, cationic surfactants, etc.), and organic acids. These coagulants may be used alone or in combination of two or more. Among these coagulants, it is preferable to use at least one coagulant selected from the group consisting of polyvalent metal salts and organic acids from the viewpoint of excellent reactivity with the resin contained in the ink composition.

The polyvalent metal salt is a compound that is composed of divalent or higher polyvalent metal ions and anions that bind to these polyvalent metal ions and is soluble in water. Specific examples of polyvalent metal ions include ^{divalent metal ions such as Ca 2+} , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , and Ba ²⁺ ; and trivalent metal ions such as Al ³⁺ , Fe ³⁺ , and Cr ^3+. Be done. Examples of anions include Cl ⁻ , I ⁻ , Br ⁻ , SO ₄ ^2- , ClO ^3- , NO ^3- , HCOO ⁻ , CH ₃ COO ^{− and the} like. Among these polyvalent metal salts, calcium salts and magnesium salts are preferable from the viewpoint of stability of the reaction solution and reactivity as a flocculant.

Examples of organic acids include sulfuric acid, hydrochloric acid, nitrate, phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid and tartrate acid. , Lactic acid, sulfonic acid, ortholic acid, pyrrolidone carboxylic acid, pyroncarboxylic acid, pyrrolcarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumarin acid, thiophenecarboxylic acid, nicotinic acid, or derivatives of these compounds, or salts thereof. Etc. are preferably mentioned. The organic acid may be used alone or in combination of two or more.

Examples of the cationic resin include a cationic urethane resin, a cationic olefin resin, and a cationic allylamine resin.

As the cationic urethane resin, known ones can be appropriately selected and used. As the cationic urethane resin, commercially available products can be used, for example, Hydran CP-7010, CP-7020, CP-7030, CP-7040, CP-7050, CP-7060, CP-7610 (trade names). , Dainippon Ink and Chemicals Co., Ltd.), Superflex 600, 610, 620, 630, 640, 650 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Urethane Emulsion WBR-2120C, WBR-2122C (above product name) , Taisei Fine Chemical Co., Ltd.) and the like can be used.

The cationic olefin resin has an olefin such as ethylene or propylene in its structural skeleton, and known ones can be appropriately selected and used. Further, the cationic olefin resin may be in an emulsion state in which it is dispersed in a solvent containing water, an organic solvent and the like. As the cationic olefin resin, a commercially available product can be used, and examples thereof include arrow base CB-1200 and CD-1200 (trade name, manufactured by Unitika Ltd.).

As the cationic allylamine resin, known ones can be appropriately selected and used, for example, polyallylamine hydrochloride, polyallylamineamide sulfate, allylamine hydrochloride / diallylamine hydrochloride copolymer, allylamine acetate / diallylamine acetate. Copolymers, allylamine acetate / diallylamine acetate copolymers, allylamine hydrochloride / dimethylallylamine hydrochloride copolymers, allylamine / dimethylallylamine copolymers, polydialylamine hydrochlorides, polymethyldiallylamine hydrochlorides, polymethyldialylamineamide sulfates, polymethyldiallylamine acetates , Polydialyldimethylammonium chloride, diallylamine acetate / sulfur dioxide copolymer, diallylmethylethylammonium ethylsulfate / sulfur dioxide copolymer, methyldialylamine hydrochloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / Examples thereof include acrylamide copolymers. As such a cationic allylamine-based resin, commercially available products can be used, for example, PAA-HCL-01, PAA-HCL-03, PAA-HCL-05, PAA-HCL-3L, PAA-HCL-. 10L, PAA-H-HCL, PAA-SA, PAA-01, PAA-03, PAA-05, PAA-08, PAA-15, PAA-15C, PAA-25, PAA-H-10C, PAA-D11- HCL, PAA-D41-HCL, PAA-D19-HCL, PAS-21CL, PAS-M-1L, PAS-M-1, PAS-22SA, PAS-M-1A, PAS-H-1L, PAS-H- 5L, PAS-H-10L, PAS-92, PAS-92A, PAS-J-81L, PAS-J-81 (trade name, manufactured by Nittobo Medical Co., Ltd.), Hymo Neo-600, Hymorok Q-101, Q-311 , Q-501, Himax SC-505, SC-505 (trade name, manufactured by Hymo Co., Ltd.) and the like can be used.

Examples of the cationic surfactant include primary, secondary and tertiary amine salt type compounds, alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalconium salts, and quaternary ammonium salts. Examples thereof include a quaternary alkylammonium salt, an alkylpyridinium salt, a sulfonium salt, a phosphonium salt, an onium salt, and an imidazolinium salt. Specific examples of the cationic surfactant include hydrochlorides such as laurylamine, palmamine and rosinamine, acetates and the like, lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, benzyltributylammonium chloride, benzalconium chloride and dimethylethyllaurylammonium. Ethyl sulfate, dimethylethyloctylammonium ethyl sulfate, trimethyllaurylammonium hydrochloride, cetylpyridinium chloride, cetylpyridinium bromide, dihydroxyethyllaurylamine, decyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium chloride, tetradecyldimethylammonium chloride, hexa Examples thereof include decyldimethylammonium chloride and octadecyldimethylammonium chloride.

The flocculant may have a solubility in water of 600 g / L or less. In the present embodiment, since the inkjet head is maintained using the maintenance liquid described later, the nozzle surface is discharged by the reaction liquid even when the solubility in water is low and the flocculant is likely to precipitate due to the nozzle surface drying. It is possible to eliminate defects. The effect of the present invention can be obtained even if the solubility in water is 500 g / L or less, and further, the effect of the present invention can be obtained even if the solubility in water is 400 g / L or less, further 300 g / L or less. can get.

The concentration of the flocculant in the reaction solution may be 0.03 mol / kg or more in 1 kg of the reaction solution. Further, it may be 0.1 mol / kg or more and 1.5 mol / kg or less, or 0.2 mol / kg or more and 0.9 mol / kg or less in 1 kg of the reaction solution. The content of the flocculant may be, for example, 0.1% by mass or more and 25% by mass or less, or 0.2% by mass or more and 20% by mass or less, based on the total mass of the reaction solution. It may be 0.3% by mass or more and 10% by mass or less.

The confirmation that the coagulant reacts with the resin contained in the ink composition can be confirmed by, for example, whether or not the resin coheses in the "resin cohesiveness test". In the "resin cohesiveness test", for example, a coagulant solution adjusted to a predetermined concentration is added dropwise to a resin liquid containing a resin at a predetermined concentration while mixing and stirring, and it is visually checked whether or not a precipitate is generated in the mixed liquid. Do it by confirming.

3.2. Water The reaction solution used in this embodiment preferably uses water as the main solvent. This water is a component that evaporates and scatters due to drying after adhering the reaction solution to the recording medium. The water is preferably water in which ionic impurities such as pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water or ultrapure water are removed as much as possible. Further, it is preferable to use water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide because the growth of mold and bacteria can be prevented when the reaction solution is stored for a long period of time. The content of water contained in the reaction solution can be, for example, 40% by mass or more, preferably 50% by mass or more, and more preferably 55% by mass or more, based on the total mass of the reaction solution. , More preferably 65% by mass or more.

3.3. Organic solvent An organic solvent may be added to the reaction solution used in the present embodiment. By adding an organic solvent, the wettability of the reaction solution with respect to the recording medium can be improved. As the organic solvent, the same organic solvent as those exemplified in the above-mentioned ink composition can be used. The content of the organic solvent is not particularly limited, but can be, for example, 1% by mass or more and 40% by mass or less, preferably 5% by mass or more and 30% by mass, based on the total mass of the reaction solution. It is as follows.

The reaction solution preferably contains a water-soluble organic solvent having a standard boiling point of 280 ° C. or lower as an organic solvent, and the content of the water-soluble organic solvent having a standard boiling point of more than 280 ° C. is 3% by mass or less. It is more preferably 1% by mass or less, and further preferably 0.5% by mass or less. In this case, since the reaction solution has good drying property, the reaction solution is quickly dried, and the recorded material obtained in the recording step is excellent in stickiness reduction and abrasion resistance.

As the water-soluble organic solvent having a standard boiling point of 280 ° C. or lower, at least one water-soluble organic solvent such as a pyrrolidone derivative, an alkanediol and an alkylene glycol monoether derivative is preferably used. The standard boiling point of the water-soluble organic solvent is preferably 250 ° C. or lower, more preferably 230 ° C. or lower, and even more preferably 210 ° C. or lower. The content of the water-soluble organic solvent having a standard boiling point of 280 ° C. or lower is more preferably 5% by mass or more, further preferably 10% by mass or more, and more preferably 15% by mass or more. preferable.

3.4. Surfactant A surfactant may be added to the reaction solution used in the present embodiment. By adding a surfactant, the surface tension of the reaction solution can be reduced and the wettability with the recording medium can be improved. Among the surfactants, for example, acetylene glycol-based surfactants, silicon-based surfactants, and fluorine-based surfactants can be preferably used. As specific examples of these surfactants, the same surfactants as those exemplified in the above-mentioned ink composition can be used. The content of the surfactant is not particularly limited, but can be 0.1% by mass or more and 1.5% by mass or less with respect to the total mass of the reaction solution.

3.5. Other Ingredients A pH adjuster, a preservative / antifungal agent, a rust preventive, a chelating agent and the like may be added to the reaction solution used in the present embodiment, if necessary.

3.6. Physical Properties of Reaction Solution The reaction solution used in this embodiment preferably has a surface tension of 20 mN / m or more and 40 mN / m at 20 ° C., and is 20 mN / m or more and 35 mN / m when discharged by an inkjet recording head. It is more preferably m or less. The surface tension is measured by, for example, using an automatic tensiometer CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) to wet the platinum plate with the reaction solution in an environment of 20 ° C. Can be measured by confirming.

From the same viewpoint, the viscosity of the reaction solution used in the present embodiment at 20 ° C. is preferably 3 mPa · s or more and 10 mPa · s or less, and more preferably 3 mPa · s or more and 8 mPa · s or less. .. The viscosity can be measured by using, for example, a viscoelasticity tester MCR-300 (trade name, manufactured by Pysica) in an environment of 20 ° C.

3.7. Method for preparing reaction solution The reaction solution used in this embodiment can be produced by dispersing and mixing each of the above components by an appropriate method. After sufficiently stirring each of the above components, filtration is performed to remove coarse particles and foreign substances that cause clogging, and a desired reaction solution can be obtained.

4. Recording medium In the present embodiment, the recording medium to be printed is not particularly limited, but a recording medium having low ink absorption or non-absorption of ink can be used. According to the recording method of the present embodiment described later, by controlling the surface temperature of the recording medium after the ink composition adhesion step so as to be within a predetermined temperature change, the dimensional change due to thermal expansion of the recording medium is prevented. Further, by controlling the surface temperature of the recording medium so as to be within a predetermined temperature change, the ink is sufficiently dried in the transport path, so that the obtained image quality and the scratch resistance of the image are also improved.

The term "ink low-absorbent or non-absorbent recording medium" as used herein refers to a recording medium having the property of not absorbing or hardly absorbing the ink composition. Quantitatively, the ink non-absorbent or low-absorbency recording medium is "a recording medium in which the ^{amount of water absorbed from the start of contact to 30 msec 1/2} in the Bristow method is 10 mL / m ² or less". Point to. 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 Technical Association of the Pulp and Paper (JAPAN TAPPI). For details of the test method, refer to the standard No. of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition". 51 "Paper and Paperboard-Liquid Absorption Test Method-Bristow Method". On the other hand, the ink-absorbent recording medium refers to a recording medium that does not correspond to an ink-non-absorbent or low-absorbency recording medium.

Examples of the non-ink-absorbing recording medium include a plastic film having no ink-absorbing layer, a material coated with plastic on a base material such as paper, and a medium to which a plastic film is adhered. .. Examples of the plastic referred to here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene and the like.

Examples of the recording medium having low ink absorption include a recording medium provided with a coating layer for receiving ink on the surface. For example, a recording medium whose base material is paper includes art paper, coated paper, and matte. Printing of paper, etc. When this paper is a plastic film, the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc. is coated with a hydrophilic polymer. , Silica, titanium and other particles are coated together with a binder. These recording media may be transparent recording media.

A recording medium with a release paper can also be used as the recording medium. As will be described later, in the present embodiment, by controlling the surface temperature of the recording medium after the ink composition adhesion step so as to be within a predetermined temperature change, the dimensional change due to thermal expansion of the recording medium is prevented. Even when the recording medium is a recording medium with a release paper, the occurrence of a volume expansion difference between the release paper and the recording medium can be suppressed to prevent deformation of the recording medium, and the image quality and / or abrasion resistance are excellent. A recording method can be provided.

Examples of such a recording medium with a release paper include a film made of polyvinyl chloride, which is an example of a resin material, and a release paper, which is an example of a paper material, laminated via an adhesive material. Such recording media are widely used for signing applications such as advertisements posted indoors and outdoors. In this case, various recordings are performed on the recording surface with the film side made of polyvinyl chloride as the recording surface, the release paper laminated on the back side of the recording surface is peeled off, and the film is attached to various base materials. , The film can be used as an advertisement.

Further, as a recording medium with a release paper, a label paper in which a plurality of labels are attached at intervals to a strip-shaped release paper (roll paper) can be mentioned. The back of the label is a sticker, and the label can be peeled off from the release paper along the frame. In such a strip-shaped release paper, the area corresponding to the label is the recording surface, which is an area on which an image can be printed.

The recording medium used in the present embodiment can have a medium width of 350 mm or more. In the recording method according to the present embodiment described later, even in a large recording medium having a medium width of 350 mm or more, the recording medium can be deformed by controlling the temperature without providing a large furnace or the like. It is possible to provide a recording method that can be prevented and has excellent image quality and / or scratch resistance. Further, the larger the medium width, the larger the thermal expansion and thermal deformation of the recording medium, the larger the transfer error of the recording medium due to the transfer, and the larger the twist of the recording medium. The recording method of the present embodiment is particularly useful in that it can be reduced.

In the present embodiment, the lower limit of the medium width of the recording medium is not limited, but is preferably 300 mm or more, more preferably 350 mm or more, further preferably 700 mm or more, further preferably 1000 mm or more, and particularly preferably 1300 mm or more. .. The upper limit of the medium width of the recording medium is not limited, but is preferably 4000 mm or less, more preferably 3000 mm or less, and even more preferably 2000 mm or less. When the medium width of the recording medium is within the above range, it is preferable in that it is possible to record a recorded object having a large area and that the amount of deformation of the recording medium can be reduced.

The recording medium used in the present embodiment preferably has a coefficient of linear expansion ( ^10-5 / ° C.) in the range of 5 to 30, more preferably in the range of 6 to 27, and even more preferably in the range of 7 to 7. It is in the range of 25. When the coefficient of linear expansion of the recording medium is within the above range, the amount of deformation of the recording medium can be reduced. The recording medium used in the present embodiment preferably has a Young's modulus (GPa) in the range of 0.1 to 5, more preferably in the range of 0.5 to 4, and even more preferably in the range of 1 to 3. Is the range of. When the Young's modulus of the recording medium is within the above range, the amount of deformation of the recording medium can be reduced.

5. Recording method The recording method according to the present embodiment uses the above-mentioned recording apparatus to record on a recording medium using ink, and includes an ink composition attaching step of adhering the ink composition to the recording medium. The primary drying step of heating the surface temperature of the recording medium to the primary drying temperature at the time of adhering the ink composition to the recording medium and the secondary drying of the recording medium subjected to the ink composition adhering step are performed. A transport step of transporting the ink composition to the means and a secondary drying step of heating the surface temperature of the recording medium to the secondary drying temperature by the secondary drying means are provided, and the ink composition adheres to the recording medium. From the completion to the completion of the secondary drying step, the minimum temperature change of the surface temperature of the recording medium with respect to the primary drying temperature (° C.) is -40% or more, the maximum temperature change is 370% or less, and the recording. The average temperature rise rate from the completion of adhesion of the ink composition to the medium until the surface temperature of the recording medium reaches the secondary drying temperature is 7 (° C./s) or less. Hereinafter, each step will be described. Note that FIG. 2 is a diagram showing changes in the surface temperature of the recording medium in the recording method according to the embodiment of the present invention.

5.1. Ink Composition Adhesion Step In the recording method according to the present embodiment, the ink composition adhesion step is a step of adhering the ink composition to the recording medium. That is, in FIG. 1, it is a step of ejecting and adhering the ink composition to the roll paper 1 which is a recording medium from the recording head 11. As a result, the ink composition is adhered to the roll paper 1 which is a recording medium, and an image is formed in the print area.

In the ink composition adhesion step, the lower limit of the maximum adhesion amount of the ink composition to the printing area of the recording medium ^{is preferably 3 mg / inch 2} or more, more preferably 5 mg / inch ² or more, and 10 mg. It is more preferable that / inch is ^{2 or more.} Further, the upper limit of the maximum amount of the ink composition adhered to the printing area of the recording medium ^{is preferably 20 mg / inch 2} or less, more preferably 15 mg / inch ² or less, and 13 mg / inch ² or less. It is more preferable to have. When the amount of the ink composition adhered is within the above range, the image quality is excellent. Further, even in a recording method in which the amount of the ink composition adhered is within the above range, deformation of the recording medium can be prevented by the following temperature control, and a recording method having excellent image quality and / or scratch resistance can be provided. ..

5.2. Primary Drying Step In the recording method according to the present embodiment, in the primary drying step, in the ink composition attaching step, the surface temperature of the recording medium at the time of attaching the ink composition to the recording medium is determined by the primary drying means (first). This is a step of heating to the primary drying temperature using the heating unit) 70. By this step, bleeding of the ink composition adhering to the roll paper 1 can be suppressed. Regarding the primary drying temperature in the primary drying step, the upper limit of the surface temperature of the recording medium is preferably 60 ° C. or lower, more preferably 50 ° C. or lower, still more preferably 45 ° C. or lower, still more preferably 40 ° C. or lower, particularly preferably 38. Heat to below ° C. Further, the recording medium is heated so that the lower limit of the surface temperature is preferably 30 ° C. or higher, more preferably 32 ° C. or higher, and particularly preferably 35 ° C. or higher. When the surface temperature of the recording medium is 60 ° C. or lower, heating of the inkjet head is suppressed, nozzle removal during printing is suppressed, and continuous ejection stability is further improved. Further, when the surface temperature of the recording medium is 30 ° C. or higher, the dot filling property of the ink composition on the recording medium, particularly the non-absorbent recording medium such as vinyl chloride, is further improved, and the image quality is further improved. .. Here, the primary drying temperature (° C.) means the maximum temperature of the surface of the recording medium when the ink adheres.

5.3. Transport Step In the recording method according to the present embodiment, the transport step is a step of transporting the recording medium on which the ink composition adhesion step has been performed to the second heating unit 80, which is a secondary drying means. As a result, the roll paper 1 which is a recording medium is conveyed to the secondary heating region. The transport speed (mm / s) in the transport process is a value obtained by dividing the PP length (mm) by the PP time (s), and the PP length (mm) is the ink of the recording medium. The distance from the completion of the adhesion of the ink to the secondary drying temperature, and the PP time (s) means the time from the completion of the adhesion of the ink to the secondary drying temperature at a certain point on the recording medium. do. This transport speed (mm / s) is preferably 1 mm / s or more, more preferably 5 mm / s or more, and 10 m, from the viewpoint of print productivity.
It is more preferably m / s or more.

5.4. Secondary drying step In the recording method according to the present embodiment, in the secondary drying step, the surface temperature of the recording medium on which the ink composition adhering step is performed is secondarily determined by the second heating unit 80, which is the secondary drying means. This is a process of heating to a drying temperature. By this step, the ink composition adhering to the roll paper 1 can be dried more quickly. The secondary drying temperature in the secondary drying step is preferably equal to or higher than the primary drying temperature, more preferably 10 ° C. or higher than the primary drying temperature, further preferably 20 ° C. or higher, and more preferably 30 ° C. or higher. It is more preferable, and it is even more preferable that the temperature is 40 ° C. or higher. The secondary drying temperature is preferably 100 ° C. or lower higher than the primary drying temperature. When the secondary drying temperature is within the above range, deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or abrasion resistance can be provided.

That is, as for the secondary drying temperature in the secondary drying step, the upper limit of the surface temperature of the recording medium is preferably 160 ° C. or lower, more preferably 150 ° C. or lower, still more preferably 145 ° C. or lower, still more preferably 140 ° C. or lower. Heat to become. Further, the recording medium is heated so that the lower limit of the surface temperature is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and particularly preferably 70 ° C. or higher. In the present embodiment, since the first heating unit 70 and the second heating unit 80 of the recording device, that is, the primary heating region and the secondary heating region are separately provided, the second heating unit 80 The recording head 11 in the primary heating region is less likely to be affected by the secondary drying temperature, and the discharge is less likely to be affected.

Further, in the recording method according to the present embodiment, the minimum temperature with respect to the primary drying temperature (° C.) of the surface temperature of the recording medium from the completion of adhesion of the ink composition to the recording medium to the completion of the secondary drying step. The change is -40% or more, the maximum temperature change is 370% or less, and the average temperature rise from the completion of adhesion of the ink composition to the recording medium until the surface temperature of the recording medium reaches the secondary drying temperature. The speed is 7 (° C./s) or less. In the present embodiment, by controlling the surface temperature of the recording medium after the ink composition adhesion step so as to be within such a temperature change, the dimensional change due to thermal expansion of the recording medium is prevented. Further, by controlling the surface temperature of the recording medium so as to be within a predetermined temperature change, the ink is sufficiently dried in the transport path, so that the obtained image quality and / or the scratch resistance of the image are also improved. Further, by setting the minimum temperature change of the surface temperature of the recording medium with respect to the primary drying temperature (° C.) to −40% or more and the maximum temperature change to 370% or less, heat is not wasted and energy is saved.

Here, the secondary drying temperature (° C.) is the maximum temperature of the recording medium surface in the secondary heating region, and the minimum temperature (° C.) is the minimum temperature of the recording medium surface in the recording method according to the present embodiment. means. Therefore, the minimum temperature change (%) means {(minimum temperature-primary drying temperature) / primary drying temperature} × 100. Further, the maximum temperature change (%) means {(secondary drying temperature-primary drying temperature) / primary drying temperature} × 100. The average heating rate (° C./s) means: {(secondary drying temperature-primary drying temperature) / PP time} × 100. For the minimum temperature change and the maximum temperature change, the value rounded to the first decimal place is used, and for the average temperature rise rate, the value rounded to the third decimal place is used.

In FIG. 2, arrow A indicates a temperature change until the surface temperature of the recording medium after the primary drying step reaches the minimum temperature, and the temperature change with respect to the primary drying temperature is the minimum temperature change. Further, arrow B indicates a temperature change until the surface temperature of the recording medium after the primary drying step reaches the maximum temperature, and the temperature change with respect to the primary drying temperature is the maximum temperature change.

In the recording method according to the present embodiment, the lower limit of the minimum temperature change is preferably −35% or more, more preferably −30% or more, still more preferably −20% or more.
More preferably, it is -10% or more, and particularly preferably -7% or more. On the other hand, the upper limit of the minimum temperature change is preferably 0% or less, more preferably -3% or less, still more preferably -5% or less, and even more preferably -10% or less. The minimum temperature change is preferably high from the viewpoint of suppressing the dimensional change. On the other hand, from the viewpoint of simplifying the heating mechanism and the heat retaining mechanism of the transport path, it is preferable that the minimum temperature change is low. The surface temperature of the recording medium when the minimum temperature changes is preferably higher than the surface temperature of the recording medium when the recording medium is left in the transport path with the recording device stopped. More specifically, when the minimum temperature change of the recording medium heated by the primary drying causes the transport path to be transported with the heating mechanism provided in the transport path stopped, or when the heat retention mechanism provided in the transport path is removed. It is preferable that the temperature change is higher than the minimum temperature change when the product is transported through the transport path (the decrease in temperature is small).

Further, in the recording method according to the present embodiment, the upper limit value of the maximum temperature change is preferably 350% or less, more preferably 300% or less, and the lower limit value is preferably 0% or more, more preferably. Is 20% or more, more preferably 30% or more, even more preferably 50% or more, even more preferably 70% or more, 100% or more, 150% or more, even 200% or more, most. It is preferably 250% or more. In terms of dimensional change, it is preferable that the maximum temperature change is low, but in terms of scratch resistance of the obtained image, it is preferable that the maximum temperature change is high.

Further, in the recording method according to the present embodiment, the upper limit of the average heating rate is preferably 6 (° C./s) or less, more preferably 5 (° C./s) or less, and 4 (° C./s). s) It is more preferable that it is less than or equal to s). Further, the lower limit of the average temperature rising rate is preferably 0.2 (° C./s) or more, more preferably 1 (° C./s) or more, and 2 (° C./s) or more. More preferred. When the average heating rate is within the above range, the dimensional change is prevented, and the obtained image quality and the scratch resistance of the image are also improved.

The time from the completion of adhesion of the ink composition to the recording medium to reaching the secondary drying temperature is preferably 250 seconds or less, more preferably 100 seconds or less, and 80 seconds or less. Is more preferable, and most preferably within 60 seconds. The lower limit is not limited, but 5 seconds or more is preferable, and 10 seconds or more is more preferable. By setting the time from the completion of adhesion of the ink composition to the recording medium to reaching the secondary drying temperature within 250 seconds, deformation of the recording medium can be further prevented, and a recording method having excellent image quality and / or abrasion resistance. Can be provided. It is also preferable because of the ease of designing the recording device.

Further, the time from the completion of adhesion of the ink composition to the recording medium until the recording medium is conveyed to the secondary drying means and reaches the secondary drying temperature can be the same as the time in the previous stage. It is preferably 60 seconds or less, more preferably 50 seconds or less, further preferably 40 seconds or less, and most preferably 30 seconds or less. The time from the completion of adhesion of the ink composition to the recording medium until the recording medium is conveyed to the secondary drying means and reaches the secondary drying temperature is 60 seconds or less, so that the deformation of the recording medium can be further prevented. It is possible to provide a recording method having excellent image quality and / or scratch resistance.

5.5. Other processes <Preheating process>
In the recording method according to the present embodiment, it is preferable to perform a preheating step of preheating the recording medium prior to the ink composition adhesion step. In the preheating step, the roll paper 1 which is a recording medium is preheated in the above-mentioned preheating unit 60. Since the surface of the recording medium is heated by this step, the temperature change in the ink composition adhesion step is small, the deformation of the recording medium can be prevented, and a recording method having excellent image quality and / or scratch resistance can be provided. .. The preheating temperature in the preheating step is preferably a temperature similar to the primary drying temperature in the primary drying step. For example, the upper limit of the surface temperature of the recording medium is preferably 60 ° C. or lower, more preferably 50 ° C. or lower. , More preferably 45 ° C. or lower, even more preferably 40 ° C. or lower, and particularly preferably 38 ° C. or lower. Further, the recording medium is heated so that the lower limit of the surface temperature is preferably 30 ° C. or higher, more preferably 32 ° C. or higher, and particularly preferably 35 ° C. or higher.

<Reaction liquid adhesion process>
In the recording method according to the present embodiment, prior to the ink composition adhering step, a reaction liquid adhering step may be performed in which the reaction liquid is preliminarily applied to the region where the image is formed on the recording medium. The reaction solution adhering step is preferable because the image quality can be further improved.

As a method for adhering the reaction solution, for example, any method such as spin coating, spray coating, gravure roll coating, reverse roll coating, bar coating, and inkjet method can be used. Among these, it is preferable to use the inkjet method (inkjet recording method). When the inkjet method is used, droplets of the reaction solution are ejected from the nozzle of the inkjet recording head and adhered to the recording medium. Since the surface tension of the above-mentioned reaction liquid can be easily set to a value suitable for the inkjet recording method by the organic solvent contained therein, the discharge stability when the reaction liquid is discharged from the nozzle is improved.

After the reaction liquid adhering step and before the ink composition adhering step, a step of drying the reaction liquid applied to the recording medium may be provided. In this case, for example, when the reaction solution adheres to the recording medium is touched, it is dried to the extent that stickiness is not felt. The drying step of the reaction solution may be carried out by natural drying, but from the viewpoint of improving the drying rate and the like, drying accompanied by heating is preferable.

As described above, in the recording method according to the present embodiment, the surface temperature of the recording medium after the ink composition adhesion step is controlled so as to be within a predetermined temperature change, so that the dimensional change due to thermal expansion of the recording medium is performed. Is prevented. In particular, by controlling the temperature of the primary heating region so as not to drop and controlling the temperature change between the primary heating region and the secondary heating region so as not to be large, the dimensional change due to thermal expansion of the recording medium is prevented. NS. Further, by controlling the surface temperature of the recording medium so as to be within a predetermined temperature change, the ink is sufficiently dried in the transport path, so that the obtained image quality and the scratch resistance of the image are also improved. Further, by setting the minimum temperature change of the surface temperature of the recording medium with respect to the primary drying temperature (° C.) to −40% or more and the maximum temperature change to 370% or less, heat is not wasted and energy is saved.

6. Examples and Comparative Examples Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

6.1. Preparation of Solvent-based Ink Composition Only the amount of organic solvent corresponding to the concentration shown in Table 1 was stirred for each ink in a container to obtain a mixed solvent. A part of the obtained mixed solvent is set aside, Solspace37500 (trade name, manufactured by LUBRIZOL) and a pigment are added in a predetermined amount, pre-dispersed using a homogenizer, and then zirconia beads having a diameter of 0.3 mm are obtained. By carrying out the dispersion treatment with a packed bead mill, a pigment dispersion having an average particle size of 130 nm was obtained. Then, a resin was added to a part of the mixed solvent and stirred to obtain a dissolved resin solution. Ink 1 is obtained by mixing the rest of the mixed solvent, the surfactant and the above resin solution into the above pigment dispersion, stirring for 1 hour, and then filtering using a 5 μm PTFE membrane filter. rice field. All the values in Table 1 indicate mass%.

The components used in Table 1 are as follows.
PB-15: 3 (CI Pigment Blue 15: 3, copper phthalocyanine pigment)
-Solspec 37500 (trade name, manufactured by LUBRIZOL, resin dispersant)
-Γ-Butyrolactone (standard boiling point 204 ° C)
-DEGBME (diethylene glycol butyl methyl ether, standard boiling point 212 ° C)
-DEGMEE (diethylene glycol methyl ethyl ether, standard boiling point 176 ° C)
・ BYK340 (trade name, manufactured by Big Chemie Japan Co., Ltd., fluorine-based surfactant)
HM515 (trade name "Kanevinyl HM515", manufactured by Kaneka Corporation, vinyl chloride-vinyl acetate copolymer)

6.2. Preparation of water-based ink composition Inks 2 and 3 were prepared by mixing and stirring each component so as to have the blending ratio shown in Table 2 and then filtering with a 10 μm membrane filter. All the values in Table 2 show mass%, and ion-exchanged water was added so that the total mass of the water-based ink composition was 100% by mass.

The components used in Table 2 are as follows.
・ BYK348 (trade name, manufactured by Big Chemie Japan Co., Ltd., silicone-based surfactant)
・ DF110D (trade name "Surfinol DF110D", manufactured by Nisshin Kagaku Kogyo Co., Ltd., acetylene-based surfactant)
・ John Krill 7610 (trade name, manufactured by BASF Japan Ltd., styrene acrylic resin)
・ AQUACER593 (trade name, manufactured by Big Chemie Japan Co., Ltd., polypropylene wax)
・ EDTA (sodium ethylenediaminetetraacetate)

6.3. Preparation of reaction solution Each reaction solution was prepared by mixing and stirring each component so as to have the blending ratio shown in Table 3 and then filtering the mixture with a 10 μm membrane filter. All the values in Table 3 showed mass%, and ion-exchanged water was added so that the total mass of the reaction solution was 100% by mass.

The surfactants (BYK348, DF110D) used in Table 3 have the same components as those in Table 2.

6.4. Evaluation method 6.4.1. Creation of recorded materials (for image quality evaluation)
Inkjet printer: The recording medium was carried into a modified machine of SC-S50650 (manufactured by Seiko Epson Corporation), and the color ink filled in one nozzle row of the head was inkjet coated with ^{a resolution of 720 x 1440 dpi and an adhesion amount of 10 mg / inch 2.} bottom. When a reaction solution is used, the reaction solution filled in one nozzle row of the reaction solution heads staggered on the upstream side in the recording medium transport direction of the ink head before adhering the color ink is charged with a resolution of 720 × 720 dpi, 1 Inkjet coating was performed at an adhesion amount of 0.0 mg / inch ^2. The temperature of the recording medium during the adhesion of the reaction solution was the same as the temperature at the time of ink printing in Table 4. The position of the secondary drying furnace can be moved, the length up to the secondary drying furnace can be adjusted, and a hood is provided in the transfer furnace.

Specifically, the modified machine of SC-S50650 is as follows. The printing unit hood was modified to cover the drying oven, and the drying oven length was set to be different for each example. The degree of release (release angle) of the hood was adjusted for each example, and the minimum temperature change was adjusted. In addition, the transport speed and the PP time were adjusted by providing an interval time between the main scan and the sub scan. The temperature was measured by attaching a thermocouple to the surface of the recording surface of the recording medium, and measuring the maximum temperature, the minimum temperature, and the respective times. The printing temperature of 25 ° C. was recorded at room temperature because the primary heating was turned off and the primary heating was not performed.

In addition, each item in Table 4 is as follows.
-Primary drying temperature (° C): The maximum temperature on the surface of the recording medium when ink adheres.
Transport speed (mm / s): A value obtained by dividing the PP length (mm) by the PP time (s).
-Secondary drying temperature (° C): The maximum temperature of the recording medium surface in the secondary drying furnace.
-PP time (s): The time from the completion of ink adhesion to the reaching the secondary drying temperature at a certain point on the recording medium.
-Minimum temperature (° C): The minimum temperature on the surface of the recording medium.
-Minimum temperature change (%): {(Minimum temperature-primary drying temperature) / primary drying temperature} x 100
-Maximum temperature change (%): {(secondary drying temperature-primary drying temperature) / primary drying temperature} x 100
-Average temperature rise rate (° C./s): {(secondary drying temperature-primary drying temperature) / PP time} x 100
-Recording medium type: The recording medium 1 is a polyvinyl chloride sheet (manufactured by ORAFOL Co., Ltd., product number ORAJET 3164XG-010 (1370 mm) glossy vinyl chloride glue; width 1370 mm). The recording medium 2 is processed so that the width of the recording medium 1 is narrowed to a width of 300 mm.
-PP length (mm): The distance from the completion of ink adhesion on the recording medium to the reaching the secondary drying temperature.
For the minimum temperature change and the maximum temperature change, the value rounded to the first decimal place was used, and for the average temperature rise rate, the value rounded to the third decimal place was used.

6.4.2. Dimensional stability evaluation A release paper of a recording medium in which an image of 1250 x 600 mm (270 x 600 mm for recording medium 2) was created for recording medium 1 and dried under the conditions shown in Table 4. The dimensional difference between the edges in the width direction was measured, and the amount of deformation in the width direction was calculated. Here, if the amount of deformation is less than 1%, it is within the range that can be actually used.

6.4.3. Evaluation of Image Quality As described above, a solid pattern of 10 mm × 10 mm was recorded, the presence or absence of printing unevenness was visually confirmed, and evaluation was performed according to the following criteria.
A: It is not observed that the ink density is uneven in the pattern.
B: The appearance of uneven ink density in the pattern is not visually observed, but is observed with a loupe.
C: Fine non-uniformity is visually observed.
D: Large non-uniformity is visually observed, but the outline of the pattern is clear.
E: The outline of the pattern is also blurred, and the outline is blurred.

6.4.4. Evaluation of abrasion resistance The abrasion resistance was evaluated using the Gakushin type friction fastness tester AB-301 (trade name, manufactured by Tester Sangyo Co., Ltd.). Specifically, the surface of the recording medium on which the image was recorded was rubbed with a friction element to which a white cotton cloth (JIS L 0803 compliant) was attached until the coating film was peeled off by applying a load of 300 g or 30 reciprocations. Then, the degree of peeling of the image (coating film) on the surface of the recording medium was visually observed. The evaluation criteria are as follows.
A: Peeling of the coating film was observed after 20 reciprocations or more and 29 reciprocations or less.
B: Peeling of the coating film was observed after 10 reciprocations or more and 19 reciprocations or less.
C: Peeling of the coating film was observed within 9 round trips.

6.4.5. Evaluation of printing speed Whether or not it is preferable in terms of printing productivity was evaluated according to the following criteria.
A: The transport speed is 10 mm / s or more.
B: The transport speed is 1 mm / s or more and less than 10 mm / s.
C: The transport speed is less than 1 mm / s.

6.4.6. Evaluation of Discharge Stability Recording was performed continuously for 1 hour under the conditions of "6.4.1. Creation of recorded material". After the recording was completed, the presence or absence of non-ejection of the ink nozzle row (360 nozzles) was confirmed and evaluated according to the following criteria.
A: No non-ejection nozzle.
B: 1-3 non-ejection nozzles.
C: 4 or more non-ejection nozzles.

6.4.7. Evaluation of Dimensional Stability (Visual) The part of the edge of the recording material used in the above dimensional stability evaluation in the width direction where there is a dimensional difference between the main body of the recording medium and the release paper is 50 cm from the recording medium. It was visually observed at a distance and evaluated according to the following criteria.
A: It cannot be recognized if the edge of the recording medium body and the edge of the release paper do not match.
B: It can be recognized that the edge of the recording medium body and the edge of the release paper do not match.

6.5. Evaluation Results In Examples 1 to 12, both the water-based ink and the solvent-based ink were used, and the dimensional stability was excellent and the abrasion resistance and / or the image quality was excellent as compared with the comparative example. On the other hand, in all the comparative examples, the dimensional stability was inferior, or the abrasion resistance and the image quality were inferior.

Specifically, in Examples 2 and 3, the amount of ink applied is larger than that in Example 1, but since the reaction solution is used for recording, the image quality does not deteriorate so much even if the amount of ink applied is large. rice field. However, since the amount of the solvent that permeates and swells the recording medium increases due to the large amount of ink applied, the recording medium tends to be easily deformed as the average temperature rise rate increases. In Example 4, the transport speed was slower than that in Example 1, and the secondary drying temperature was high, so that the image quality was improved, but the recording medium tended to be easily deformed. In Example 5, since the primary drying temperature was raised, the transport speed was slowed down, and the secondary drying temperature was lowered, the recording medium was more easily deformed than in Example 1, resulting in inferior discharge stability. In Example 6, since the ink contains glycerin, the image quality is inferior. In Example 7, since the reaction solution was not used, the image quality was inferior to that in Example 1. In Examples 8 and 9, since the primary drying temperature was in a preferable range, the image quality was improved as compared with Example 1, but the dimensional stability was slightly inferior. In Example 10, a solvent-based ink was used, and high results were obtained as in the case of the water-based ink. In Example 11, since the average heating rate was high, the image quality and scratch resistance were slightly inferior. In Example 12, since the amount of the reaction solution and the ink applied was larger than that in Example 1, the dimensional stability was slightly inferior.

On the other hand, in Comparative Example 1, the minimum temperature change was large and the primary drying temperature was raised, resulting in inferior dimensional stability and discharge stability. In Comparative Example 2, since the primary heating was not performed, the maximum temperature change was large, resulting in inferior image quality and dimensional stability. In Comparative Example 3, the average heating rate was too high, resulting in inferior dimensional stability. In Comparative Example 4, since the heating was not performed, the dimensions did not change, but the results were inferior in image quality and abrasion resistance. In Comparative Example 5, since the minimum temperature change was −42%, the result was inferior to the dimensional change. In Comparative Example 6, since the maximum temperature change was too large, the result was also inferior to the dimensional change.

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

1 ... Roll paper (recording medium), 10 ... Recording unit, 11 ... Recording head, 12 ... Carriage, 20 ... Conveying unit, 21A, 21B ... Roller, 30 ... Supply unit, 31 ... Feeding shaft, 40 ... Winding unit, 41 ... winding shaft, 50 ... transport path (conveyance path), 60 ... preheating section, 61 ... preheating unit, 62 ... medium support section, 70 ... first heating section (primary drying means), 72 ... platen, 75 ... housing, 80 ... second heating unit (secondary drying means), 81 ... heating unit, 82 ... medium support unit, 90 ... control unit, 100 ... printer (recording device), A ... minimum temperature change, B … Maximum temperature change, X… Transport direction

Claims (19)

The ink composition adhesion step of adhering the ink composition to the recording medium and the process of adhering the ink composition to the recording medium.
A primary drying step of heating the surface temperature of the recording medium at the time of adhesion of the ink composition to the recording medium to a primary drying temperature, and
A transport step of transporting the recording medium subjected to the ink composition adhesion step to the secondary drying means, and a transport step.
A secondary drying step of heating the surface temperature of the recording medium to the secondary drying temperature by the secondary drying means is provided.
The ink composition adhering step is performed by performing scanning a plurality of times by ejecting the ink composition from the inkjet head and adhering it to the recording medium while moving the inkjet head in the scanning direction.
The primary drying step is performed on the recording medium at a position facing the inkjet head.
The secondary drying means is located downstream of the inkjet head in the transport direction of the transport step.
The ink composition is a water-based ink composition containing a coloring material, water, a resin, and a water-soluble organic solvent.
The primary drying temperature is 30 ° C. or higher and 50 ° C. or lower, and the secondary drying temperature is 60 ° C. or higher and 160 ° C. or lower .
Wherein at the completion of deposition of the ink composition to the recording medium to the secondary drying step is complete, the lowest temperature change with respect to the primary drying temperature of the surface temperature of the recording medium (℃) is - at least 10% -3 % Or less , maximum temperature change is 20% or more and 370% or less,
The completion of deposition of the ink composition to the recording medium, the average heating rate up to the surface temperature of the recording medium reaches the secondary drying temperature state, and are 7 (℃ / s) or less,
The time from the completion of adhesion of the ink composition to the recording medium until the point at which the adhesion of the ink composition of the recording medium is completed is conveyed to the secondary drying means and reaches the secondary drying temperature is 10 Recording method that is more than a second. The recording method according to claim 1, wherein the medium width of the recording medium is 350 mm or more. The minimum temperature change, - 7% or more and -3% or less, the recording method according to claim 1 or claim 2. The recording method according to any one of claims 1 to 3, wherein the secondary drying temperature is 20 ° C. or higher higher than the primary drying temperature. The record according to any one of claims 1 to 4, wherein the time from the completion of adhesion of the ink composition to the recording medium to reaching the secondary drying temperature is 10 seconds or more and 250 seconds or less. Method. The recording method according to any one of claims 1 to 5, wherein the primary drying temperature is 30 ° C. or higher and 40 ° C. or lower. The recording method according to any one of claims 1 to 6, wherein the secondary drying temperature is 60 ° C. or higher and 140 ° C. or lower. The recording method according to any one of claims 1 to 7, wherein in the transport step, at least one of a heating means and a heat retaining means is provided in the transport path to which the recording medium is transported. The recording method according to any one of claims 1 to 8, wherein the recording medium is a recording medium with a release paper. 1. The time from the completion of adhesion of the ink composition to the recording medium until the recording medium is conveyed to the secondary drying means and reaches the secondary drying temperature is 10 seconds or more and 60 seconds or less. The recording method according to any one of claims 9. According to any one of claims 1 to 10, the length of the transport path from the point where the adhesion of the ink composition to the recording medium is completed to the time when the secondary drying temperature is reached is 500 mm or less. The recording method described. The time from the completion of adhesion of the ink composition to the recording medium until the point at which the adhesion of the ink composition of the recording medium is completed is conveyed to the secondary drying means and reaches the secondary drying temperature is 55. The recording method according to any one of claims 1 to 11 , which is seconds or more. 1. The ink composition is an aqueous ink composition containing an organic solvent having a standard boiling point of more than 280 ° C. and an organic solvent having a standard boiling point of 150 ° C. or higher and 280 ° C. or lower in an amount of 3% by mass or less. The recording method according to any one of claims 11. One of claims 1 to 13 , wherein the length of the transport path from the point where the adhesion of the ink composition to the recording medium is completed to the time when the secondary drying temperature is reached is 150 to 500 mm. The recording method described in. The recording method according to any one of claims 1 to 14, wherein recording is performed on either a non-absorbent or low-absorbent recording medium. The recording method according to any one of claims 1 to 15, further comprising a step of adhering a reaction solution containing a flocculant that agglutinates the components of the ink composition to the recording medium. The recording method according to any one of claims 1 to 16, wherein the maximum amount of the ink composition adhered to the adhesion region of the recording medium is 3 mg / inch ^{2 or more.} The recording method according to any one of claims 1 to 17, wherein the primary drying temperature is 40 ° C. or lower, and the minimum temperature change is −10% or more. A recording device for recording by the recording method according to any one of claims 1 to 18.

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