JP2011240697A - Inkjet recording apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus for suppressing an expansion speed of a medium to be recorded after printing.SOLUTION: The inkjet recording apparatus 100 includes: a printing means 190 for printing an ink composition having an amphoteric compound and a 10-60 mass percent of water on the recorded medium 101; and transfer means 140 and 150 for transferring the medium while applying a tensile force to the printed part when the ink composition is printed on the recorded medium 101 by the printing means 190.

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method.

The ink jet recording method is a recording method in which printing is performed by ejecting ink droplets from an ink jet head and landing on a recording medium such as paper. Due to recent advances in ink jet recording technology, the ink jet recording method has come to be used for high-definition image recording (printing), which has been the field of photography and offset printing.
In an ink jet recording apparatus used for such an ink jet recording method, a printed recording medium, particularly a thin recording medium, is prone to wrinkles and also floats up during transportation, so that the ink from the ink jet head to the recording medium There is a problem that the distance is not always kept constant.
Thus, various studies have been made to solve such problems. For example, Patent Document 1 improves the inconvenience that wrinkles are likely to occur and the distance from the inkjet head to the recording medium is not always kept constant, so that even if the object of image formation is thinner, it is preferable to form an image. An ink jet printer that forms an image on a recording medium to be transported with a guide surface facing an ink jet head that ejects ink and transporting the recording medium along the recording head. The platen has a flat surface that is perpendicular to the discharge direction at least within the ink discharge range of the inkjet head, and the cross-sectional shape of the platen upstream and downstream in the conveyance direction is an arc. An ink jet printer characterized by having a peripheral surface shape has been proposed.

JP 2004-90484 A

  By the way, when a thin recording medium (for example, plain paper) is used as the recording medium, there is a problem that the recording medium expands after the ink has landed. When the recording medium expands, so-called head rubbing occurs, in which the recording medium and the inkjet head come into contact with each other during printing and the image is disturbed. A method of conveying the recording medium while applying tension to the recording medium as disclosed in Patent Document 1 or conveying the recording medium while sucking from the back side of the printing surface as disclosed in Patent Document 1. Conceivable.

  However, the method of sucking the recording medium from the back side of the printing surface has a problem in terms of cost and miniaturization because the apparatus is complicated. In addition, it is advantageous in terms of head rubbing to convey the recording medium while applying tension, but the recording medium expands suddenly with printing, so there are problems such as deviation of the ink landing position and ruled line deviation. appear. Therefore, as a result of various studies to solve these problems, the present inventors have found that the expansion speed of the recording medium after printing should be reduced.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide an ink jet recording apparatus and an ink jet recording method that suppress the expansion speed of a recording medium after printing.
In addition, the expansion speed of the recording medium is suppressed, and the recording medium is expanded by applying ink, so that a tension corresponding to the expansion is applied to the recording medium, thereby avoiding rapid expansion of the recording medium due to the application of tension. It is another object of the present invention to provide an ink jet recording apparatus and an ink jet recording method that prevent the recording medium being conveyed from being bent and wrinkled.

  As a result of intensive studies to solve the above problems, the inventors of the present invention need only contain a specific component in the ink composition used for printing in order to slow the expansion speed of the recording medium after printing. As a result, the present invention has been completed.

That is, the present invention is as follows.
[1] Printing means for printing an ink composition containing a zwitterionic compound and 10 to 60% by mass of water on a recording medium;
A transporting means for transporting the ink composition while applying tension to the printed portion when the ink composition is printed on the recording medium by the printing means;
An inkjet recording apparatus comprising:
[2] The ink jet recording apparatus according to [1], wherein the zwitterionic compound is a betaine compound having a molecular weight of 100 to 250.
[3] The ink jet recording apparatus according to [1] or [2], wherein the ink composition contains 10 to 40% by mass of the zwitterionic compound with respect to the total amount thereof.
[4] The inkjet according to any one of [1] to [3], wherein the transport unit changes the strength of the tension to be applied in accordance with a discharge amount of the ink composition by the printing unit. Recording method.
[5] A printing step of printing an ink composition containing a zwitterionic compound and 10 to 60% by mass of water on a recording medium;
When printing the ink composition on a recording medium by the printing step, a conveying step of conveying while applying tension to the printed portion;
An inkjet recording method comprising:

In addition to suppressing the expansion of the recording medium by the specific ink composition, the present inventors further determine the elongation (expansion) occurring in the recording medium and determine the tension corresponding to the elongation. The ink jet recording apparatus has been conceived to avoid the occurrence of slack and wrinkles during conveyance of the recording medium.
The present invention is as follows.
[6] The inkjet recording apparatus according to any one of [1] to [4],
Furthermore, a control means for controlling the transport means is provided,
The control means transmits an expansion / contraction parameter, which is information data related to at least one of expansion and contraction of the recording medium, and determines an expansion / contraction amount determination for determining an expansion / contraction amount of the recording medium based on the expansion / contraction parameter And a drive control unit that sets a tensile force corresponding to the expansion / contraction amount determined by the expansion / contraction amount determination unit to the transport unit.
[7] The inkjet device according to [6],
The expansion / contraction amount determination unit includes a storage unit, and the storage unit stores the expansion / contraction amount corresponding to the expansion / contraction parameter for each recording medium.
[8] The inkjet device according to [6] or [7],
The expansion / contraction parameter is an ink jet apparatus including at least one of a recording medium type, an environmental condition, printing information, an ink type, and cartridge information.
[9] The inkjet recording method according to [5],
The conveying step determines the expansion / contraction amount of the recording medium based on an expansion / contraction parameter which is information data related to expansion / contraction of at least one of expansion and contraction of the recording medium, and based on the determination result An ink jet recording method for setting the tensile force.
[10] The inkjet recording method according to [9],
The ink jet recording method, wherein the expansion / contraction parameter includes at least one of a recording medium type, an environmental condition, printing information, an ink type, and cartridge information.

1 is a schematic view schematically showing an ink jet recording apparatus according to an example of the present invention. 1 is a schematic view schematically showing a part of an ink jet recording apparatus according to an example of the present invention. It is explanatory drawing which illustrates typically the example of the discharge roller which acts so that a to-be-recorded medium may be spread in the direction (for example, orthogonal direction) which cross | intersects a conveyance direction. It is explanatory drawing explaining the control part 111 with a functional block diagram. It is a flowchart explaining the elongation adjustment by the control part 111. FIG. It is the schematic which shows typically the inkjet recording device which concerns on the 2nd example of this invention. It is explanatory drawing explaining the control part 111 of the 2nd example of this invention with a functional block diagram. It is the schematic which shows typically the inkjet recording device which concerns on the 3rd example of this invention of this invention. It is explanatory drawing explaining the control part 111 of the 3rd example of this invention with a functional block diagram.

Hereinafter, a form for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary.
In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  In the following embodiments, a case where the recording medium that is an object to be printed is paper will be described, but the recording medium is not limited to paper. The idea of the present invention can be applied to a recording medium that can expand and contract during ink jet recording. Examples of the recording medium include various cut papers and roll papers, peelable seal papers, perforated papers provided with cutting holes, processed papers such as surface-treated paper suitable for photo printing, paper Sheet materials, roll-shaped resin films, sheet-like printed circuit boards for electrical circuits, etc., which are materials other than (pulp), are widely included, and the recording medium related to the present invention is not limited to the examples. Absent.

  The ink jet recording apparatus of this embodiment has a structure shown in FIGS. 1 and 2, for example. FIG. 1 is a schematic diagram schematically showing a paper transport unit in the inkjet recording apparatus, and FIG. 2 is a partial schematic diagram for explaining a method of applying tension to a recording medium after printing.

  The ink jet recording apparatus 100 of the present embodiment is a pair of transport rollers that are means for transporting a recording medium 101 printed with an ink composition containing a zwitterionic compound while applying tension to the printed portion. 140 and a pair of discharge rollers 150.

  Further, the ink jet recording method of the present embodiment includes a transporting step of transporting the recording medium 101 printed with the ink composition containing the zwitterionic compound while applying tension to the printed portion. .

  Here, the “zwitterionic compound” in the present specification is a compound having the property of an ampholyte having an acidic group and a basic group in the molecule.

  First, a description will be given with reference to FIG. In general, the line-type inkjet recording apparatus 100 capable of high-speed and high-density printing ejects ink composition droplets (hereinafter also referred to as “ink droplets”) onto a recording medium 101 such as plain paper to form an image. An inkjet head unit 190 for recording, a platen unit 120 provided below and opposite to the inkjet head unit 190, a storage cassette 104 storing a recording medium 101 before printing, and recording from the storage cassette 104 A paper feed roller 105 for feeding the medium 101, a pair of transport rollers (gate rollers) 140 for transporting the recording medium 101, and a pair of discharge rollers 150 for transporting and discharging the recording medium 101; , A paper discharge cassette 106 for storing the printed recording medium 101, a control unit 111, and a recording medium 101 to be fed And a position detection sensor 109 for position detection.

  The recording medium 101 preferably has hygroscopicity and flexibility. For example, water-soluble ink containing plain paper such as electrophotographic copying paper, silica, alumina, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and the like. Inkjet paper provided with an absorption layer may be used. Further, art paper, coated paper, cast paper, and the like used for general offset printing can be given as a type of absorbent recording medium having a relatively low penetration rate of water-soluble ink. Among these, plain paper is preferable from the viewpoint of more effectively exerting the effects of the present invention.

In the present embodiment, “plain paper” generally refers to paper that uses pulp as a main raw material and is used in a printer or the like, and is defined by JIS P 0001 number 6139. Specific examples include high-quality paper, PPC copy paper, and non-coated printing paper. As the plain paper, those commercially available from various companies can be used. For example, various papers such as Xerox 4200 (manufactured by Xerox) and GeoCycle (manufactured by Gerogia-Pacific) can be used.
Further, it is preferable that the recording medium 101 has a basis weight of 60 to 120 g / m ^{2 because} the effect of the present invention can be more effectively exhibited.

  The inkjet head unit 190 is a printing unit, and includes a plurality of inkjet heads 110 corresponding to the type of ink and a carriage (not shown) for mounting them, and each inkjet head has a full width across the width direction of the recording medium 101. Are constituted by so-called line heads in which a large number of ink discharge nozzles corresponding to each are arranged.

  The platen unit 120 conveys the recording medium 101 along the conveyance surface 120A. The conveyance surface 120 </ b> A of the platen unit 120 is a flat surface perpendicular to the ink discharge direction of the inkjet head 190. If the conveyance surface 120A has such a width that can maintain a plane state perpendicular to the landing direction when the ink composition lands on the recording medium 101, it is sufficient for good image formation. It is.

  The paper feed roller 105 is a roller for sending the recording medium 101 inside the storage cassette 104 to the transport roller 140 and is driven by a motor 118 that is driven and controlled by the control unit 111.

  The conveyance roller 140 is a part of the conveyance means, and includes a driving roller 140A as a roller unit that is driven by a motor 116 that is driven and controlled by the control unit 111, and a driven roller 140B that is driven in contact with the driving roller 140A. ing. The discharge roller 150 is a part of the conveying unit, and a drive roller 150A driven by a motor 117 driven and controlled by the control unit 111 and a driven roller 150B driven in contact with the drive roller 150A constitute a discharge roller pair. ing.

  The control unit 111 stores print data (record data) input via a interface (IF) from a CPU (Central Processing Unit), a host computer, or the like that executes print processing (record processing) and various processes in a data storage area. A RAM (Random Access Memory) for storing or temporarily storing various data, a PROM for storing a control program for controlling each unit, an EEPROM (Electrically Erasable Programmable Read-Only Memory), and the like are provided.

  As the position detection sensor 109, for example, a reflection type photosensor in which an infrared light emitting diode as a light emitting element and a phototransistor as a light receiving element are combined is used. The position detection sensor 109 is disposed in a paper conveyance unit between the paper feed roller 105 and the conveyance roller 140, detects the leading end position of the recording medium 101 being conveyed (the presence or absence of the recording medium 101), and a detection signal thereof. Is input to the control unit 111. In the control unit 111, drive control processing of the transport roller 140 is performed based on the detection signal of the leading end position of the recording medium 101.

  The recording medium 101 reaches a conveying roller 140 that rotates when the motor 116 is driven by a drive signal from the control unit 111, and the leading end surface of the recording medium 101 comes into contact with the leading end of the recording medium 101. Then, the direction is adjusted, and the paper is fed between the driving roller 140A and the driven roller 140B and fed onto the platen unit 120. Then, the recording medium 101 conveyed to the printing area below the inkjet head unit 190 by the conveyance roller 140 reaches the discharge roller 150 while being held by the conveyance roller 140. At this time, the motor 117 is driven by the drive signal from the control unit 111 to rotate the drive roller 150A, and the recording medium 101 is sandwiched between the driven roller 150B and the driven roller 150B that are driven by contact with the drive roller 150A. Is done. In this manner, the recording medium 101 is transported and moved while being sandwiched between both the transport roller 140 and the discharge roller 150, and ink droplets are ejected from the nozzles of the inkjet head unit 190 while being applied with tension. Printing based on the print data is performed.

  For printing on the recording medium 101, the control unit 111 obtains from the host computer via the IF, the print data stored in the RAM is subjected to predetermined processing in the CPU, and the head is based on this processing data. A drive signal is output to the driver, the drive signal is input to the inkjet head unit 190 via the head driver, and the electrostatic actuator to which the drive signal is input drives the ink from the corresponding nozzle to the recording medium 101. Drops are ejected, and an image is printed (recorded) based on the print data.

  However, printing on the recording medium 101 is not limited to the electrostatic suction method using the above-described electrostatic actuator. That is, the ink jet recording method in the present embodiment may be any method as long as the ink composition is ejected as droplets (ink droplets) from a fine nozzle, and the droplets land and adhere to the recording medium. This will be specifically described below.

As a first method, there is an electrostatic suction method, which applies a strong electric field between the nozzle and the acceleration electrode placed in front of the nozzle, and continuously ejects ink from the nozzle in the form of droplets. In this method, a printing information signal is supplied to the deflection electrode while the droplet is flying between the deflection electrodes and recorded, or a droplet of ink is ejected in response to the printing information signal without being deflected.
The second method is a method in which ink droplets are forcibly ejected by applying pressure to the liquid ink composition with a small pump and mechanically vibrating the nozzle with a quartz vibrator or the like. The ejected droplets are charged simultaneously with the ejection, and a printing information signal is applied to the deflection electrodes and recorded while the droplets fly between the deflection electrodes.

The third method is a method using a piezoelectric element, in which a pressure and a print information signal are simultaneously applied to a liquid ink composition by a piezoelectric element to eject and record ink droplets.
The fourth method is a method in which the liquid ink composition is rapidly expanded in volume by the action of thermal energy, and the ink composition is heated and foamed with a microelectrode in accordance with a print information signal, and the droplets are ejected and recorded. is there.
Any of the above methods can be employed in the ink jet recording method of the present embodiment.

  The recording medium 101 on which printing has been performed is fed by the transport roller 140 and the discharge roller 150, and during that time, tension is applied to the printed portion. Further, after passing through the conveying roller 140, the paper is fed only by the discharge roller 150 and stored in the paper discharge cassette 106.

  The above-described tension is applied to the recording medium 101 by adjusting the peripheral speed when the transport roller 140 and the discharge roller 150 are rotated. That is, tension is applied to the recording medium 101 by making the peripheral speed of the discharge roller 150 faster than the peripheral speed of the transport roller 140.

  The method for applying tension to the recording medium 101 is not limited to the above. For example, instead of or in addition to the above-described method, as shown in FIG. 2, tension is applied to the recording medium 101 by adjusting the positional relationship among the platen unit 120, the transport roller 140, and the discharge roller 150. Can do. That is, as shown in FIG. 2A, the portion of the discharge roller 150 that holds the recording medium 101 may be disposed below the conveying surface 120 </ b> A of the platen unit 120. In this case, the recording medium 101 is conveyed along the upper edge of the platen unit 120 on the downstream side in the conveying direction and the driven roller 150B, whereby tension is applied to the recording medium 101.

  Further, as shown in FIG. 2B, the portion of the conveyance roller 140 that holds the recording medium 101 may be disposed below the conveyance surface 120 </ b> A of the platen unit 120. In this case, the recording medium 101 is conveyed along the upper edge of the platen unit 120 on the upstream side in the conveying direction and along the driven roller 140B, whereby tension is applied to the recording medium 101. Further, as shown in FIG. 2C, a portion that sandwiches the recording medium 101 of both the conveyance roller 140 and the discharge roller 150 may be disposed below the conveyance surface 120 </ b> A of the platen unit 120. . In this case, the recording medium 101 is conveyed along the upper edge of the platen unit 120 on the upstream and downstream sides in the conveyance direction and the driven rollers 140B and 150B, whereby tension is applied to the recording medium 101.

Further, as shown in FIG. 3, the driving direction of the discharge roller 150 </ b> A (or the roller disposed in the conveyance path after ink application) with respect to the recording medium 101 is slightly inclined with respect to the conveyance direction of the recording medium 101. By disposing the recording medium 101, a slight tensile force (tension) is applied so as to widen the recording medium 101 in the width direction (direction perpendicular to the transport direction), thereby removing slack and wrinkles of the recording medium 101. it can. Further, a roller mechanism in which the distance L between the pair of discharge rollers 150A and 150A can be changed corresponding to the size of the recording medium (for example, the size of the paper).
The angle θ between the rotation direction of the discharge roller 105A (perpendicular to the rotation axis) and the paper feed direction is also variable, and the paper feed of the discharge roller 105A by the expansion / contraction amount determination unit 111B according to the expansion of the recording medium 101. You may make it change angle (theta) with a direction. As the expansion of the recording medium 101 increases, the angle θ can be increased and the tensile force in the width direction can be increased.

  Furthermore, in addition to ink jet recording using an ink composition containing the zwitterionic compound, the higher the printing density (ink composition discharge amount) with respect to the recording medium, the greater the expansion of the recording medium. You may make it change the strength of tension according to a density. Specifically, the higher the printing density and the greater the expansion of the recording medium, the stronger the tension. In order to adjust the strength of the tension according to the printing density of the recording medium, for example, the circumferential speed of the discharge roller 150 and the circumferential speed of the conveying roller 140 are changed according to the printing density of the recording medium.

  FIG. 4 shows an example in which the tension on the recording medium to be transported can be changed and the control unit is configured to set the tension of the transport mechanism according to the conditions for expanding and contracting the recording medium. Is. This figure shows a control block 111 as a control means in a functional block diagram, which is realized by the computer system chip such as the CPU, ROM, RAM, interface described above. Paper is taken as an example of the recording medium.

  The control unit 111 includes an interface (or parameter holding setting unit) 111A, an expansion / contraction amount determination unit 111B, a database unit (storage unit) 111C, a motor drive control unit 111D, and the like. The interface 111A holds expansion / contraction parameters (or expansion parameters) supplied from setting switches, sensors, computers, etc. (not shown). The expansion / contraction parameters include, for example, the type of recording medium (manufacturer, product name, type name, paper size, weight (thickness), paper quality, vertical eye, horizontal eye, etc.), environmental conditions (temperature, humidity, etc.), printing information ( Printing density, density, ink discharge amount, etc.), ink type (ink composition, etc.), cartridge information (various data recorded in the ROM of the ink cartridge, etc.), and the like. In addition, regarding the environmental condition among the expansion / contraction parameters, the ink jet apparatus may directly detect and send data to the control unit 111.

  For example, in general, JIS A-series papers have vertical eyes, and JIS B-series papers have horizontal eyes. These sheets tend to easily extend in a direction perpendicular to the direction in which the fibers are arranged. If the fiber of the paper is dry at low humidity, the difference between the front and back is not likely to occur. At low temperatures and low humidity, paper curl becomes stronger. As the printing density, ink density, and ink discharge amount increase, the moisture content of the paper fiber increases and the expansion amount increases. It is not always necessary to use all of these expansion / contraction parameters, and the approximate expansion / contraction amount may be determined by using one or a plurality of expansion / contraction parameters that greatly affect the expansion / contraction of the recording medium. In the printing by the ink jet method, when the recording medium is paper, since the paper recording medium tends to stretch due to the application of ink, the “stretching parameter” may be the “stretching parameter”. For example, when printing on both surfaces of the recording medium 101, there is a possibility that the back surface shrinks during the process. The expansion / contraction parameter can also correspond to such a condition (element) that the recording medium (paper) contracts.

  In addition, the type of paper as the expansion / contraction parameter is determined based on the recording setting by the user. Specifically, the type (for example, manufacturer, product name, type name, paper size, weight (thickness), paper quality, etc. of the recording medium recorded by the user with a host device (for example, a personal computer) connected to the inkjet device. (Vertical eye, horizontal eye, etc.), print information, ink type, and the like are selected, sent to the interface 111A, and held (stored). In the ink jet apparatus, data corresponding to the type of recording medium, print information, ink type, and the like stored in advance is transmitted from the interface 111A to the expansion / contraction determination unit 111B. The recording setting by the user is not limited to the mode performed from the host device. For example, an operation panel for inputting recording settings to the inkjet apparatus may be provided directly on the interface 111A.

  The expansion / contraction amount determination unit 111B determines the expansion / contraction amount of the recording medium after ink jet printing based on the expansion / contraction parameter. The determination is made, for example, by a relational expression obtained in advance such as the amount of expansion / contraction of the recording medium = program function f (ink amount, paper weight, humidity,...). Here, the program function f is a function (subroutine) obtained in advance, and the ink amount, paper weight, humidity,... (Parameters) are arguments of the function f. The function f is obtained by experimental data or simulation. Further, regarding temperature and humidity, which are environmental conditions, a thermometer and a hygrometer are provided in the apparatus, the current environment is directly detected using them, and the expansion / contraction part determination unit 111B is obtained using the obtained information. May determine the amount of expansion and contraction.

  The database unit 111C stores a database relating to the program function f and the amount of expansion / contraction corresponding to the expansion / contraction parameters (single or a combination of a plurality of parameters) in a readable manner.

  The drive control unit 111D is a drive circuit that can drive the motors 116 to 118 described above at a variable speed. For example, the drive control unit 111D is configured by a PLL (phase locked loop) circuit, and the motors 116 to 118 are configured by stepping motors. The drive control unit 111D includes PLL control controlled by a computer, and supplies drive pulse signals V1 to V3 to the motors 116 to 118, respectively. The motors 116 to 118 are stepping motors, for example, and operate at a rotation amount corresponding to the number of pulses of the drive pulse signal and a rotation speed corresponding to the pulse frequency.

  FIG. 5 is a flowchart for explaining the operation of the control unit 111 (expansion / contraction amount determination unit 111B). In this figure, when the CPU recognizes that tension control should be performed in a main control program (not shown), this subroutine is executed. First, the determination unit (CPU) 111B reads the expansion / contraction parameter held in the interface unit 111A (S10). Next, the expansion / contraction amount of the recording medium is calculated by introducing the value of each expansion / contraction parameter into the program function f. The corresponding data may be read from the memory matrix or the like using the expansion / contraction parameter as a direct or indirect argument (S20). The speed difference ΔV is relatively set between the motors 116 and 117 by adjusting the PLL circuit of the drive control unit 111D so as to eliminate the bending due to the determined expansion / contraction amount ΔJ of the recording medium 101. A tensile force acts on the recording medium 101 due to the speed difference between the two rollers, thereby preventing the occurrence of bending (slack) and wrinkles (S30). After setting the motor operation, return to the main control program. In the ink jet apparatus, control other than the tension control by the CPU is also performed, but since it is not particularly related to the present invention, the description thereof is omitted.

  6 and 7 show another embodiment of the present invention. In both figures, parts corresponding to those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof will be omitted. In this example, a configuration as shown in FIG. 2A is provided, and the transport roller 150 (unit) is configured to be movable up and down by a roller lifting mechanism. For example, a step motor 119A for driving the feed screw mechanism is disposed in the elevating mechanism. By supplying a drive pulse signal V4 from the drive control unit 111D to the step motor 119A, the transport roller 150 moves in the vertical direction. Positioning is performed.

In such a configuration, when the discharge roller 150 is pressed down while the recording medium 101 is sandwiched between the transport roller 140 and the discharge roller 150, the recording medium 101 is pressed against the transport surface 120 </ b> A of the platen unit 120 and the tension is increased. appear. This tension can suppress bending and wrinkling that occurs immediately after printing on the recording medium 101. In addition to the position control of the discharge roller 150, a relative speed difference between the conveyance roller 140 and the discharge roller 150 described above may be set. Specifically, a tensile force may be applied to the recording medium 101 by making the rotation speed of the discharge roller 150 relatively faster than the rotation speed of the transport roller 140. Further, the feeding roller 140 may be rotated reversely with respect to the discharge roller 150 to apply a tensile force.
When roll paper (continuous recording medium) is used as the recording medium, the state in which the recording medium 101 is sandwiched between the transport roller 140 and the discharge roller 150 can be continued.

  Further, as shown in FIG. 3 described above, a mechanism for slightly applying a pulling force to expand the recording medium 101 in the width direction (direction orthogonal to the transport direction), or the expansion / contraction parameters from the expansion / contraction amount determination unit 111B. Based on this, the mechanism for changing the tensile force on the recording medium 101 by changing the arrangement angle of the rollers with respect to the transport direction may be combined with the above-described lifting mechanism.

  8 and 9 show still another embodiment of the present invention. In both figures, parts corresponding to those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof will be omitted. In this example, the configuration as shown in FIG. 2C, that is, the arrangement of the conveying roller 140 and the arrangement of the discharge roller motor 150 are configured to be moved up and down by the lifting mechanism. By supplying the drive pulse signal V5 from the drive control unit 111D to the step motor 119B that drives the feed screw of the lifting mechanism of the transport roller 140, the transport roller 140 is movable in the vertical direction. Further, by supplying a drive pulse signal V4 from the drive control unit 111D to the step motor 119A of the lifting mechanism of the transport roller 150, the transport roller 150 is movable in the vertical direction.

In such a configuration, when the recording roller 101 and the discharge roller 150 are pressed down while the recording medium 101 is sandwiched between the conveyance roller 140 and the discharge roller 150, the recording medium 101 is pressed against the conveyance surface 120 </ b> A of the platen unit 120. Tension is generated. This tension can suppress bending and wrinkling that occurs immediately after printing on the recording medium 101.
In addition to the position control of the transport roller 140 and the discharge roller 150, a relative speed difference between the transport roller 140 and the discharge roller 150 described above may be set. Furthermore, you may combine the mechanism shown in FIG. 3 which sets a tensile force by adjusting the angle of a roller.

  The configuration other than the above provided in the inkjet recording apparatus 100 may be a conventionally known configuration.

  Next, the ink composition used in the ink jet recording apparatus and the ink jet recording method of the present embodiment will be described in detail.

  The ink composition according to the present embodiment contains water from the viewpoints of safety, handleability, and performance (color development, suitability for back-through, and ink reliability). Thus, when the ink composition containing water contains a zwitterionic compound as in this embodiment, the effects of this embodiment can be effectively exhibited.

  Further, from the viewpoint of safety and handling, the ink composition is preferably an aqueous ink composition in which the main solvent of the ink is water, and the water is ion-exchanged water, ultrafiltered water, reverse osmosis water, It is preferable to use pure water such as distilled water or ultrapure water. In particular, it is preferable to use water sterilized by ultraviolet irradiation or addition of hydrogen peroxide in order to prevent the generation of mold and bacteria and to enable long-term storage of the ink. From the viewpoint of ensuring appropriate physical property values (viscosity, etc.) of the ink and ensuring the stability and reliability of the ink, the ink composition contains 10% by mass to 60% by mass of water with respect to the total amount.

  By defining the content of water contained in the ink composition within the above range, the amount of water absorbed by cellulose in plain paper is less than that of conventional ink compositions, which is considered to cause cockling curl. It is possible to suppress swelling of cellulose that has been produced. Hereinafter, properties suitable for suppressing cockling or curling are also referred to as “cockling suitability” and “curl suitability”, respectively.

  When the water content is less than 10% by mass, the fixability to the recording medium may be lowered. On the other hand, when the water content exceeds 60% by mass, like a conventional aqueous ink composition, when printing on a recording medium having an absorption layer of a paper support with poor ink absorbability, Curling is likely to occur.

  The zwitterionic compound is not particularly limited, and examples thereof include betaine compounds, amino acids, and derivatives thereof. More specifically, as betaine compounds, glycine betaine (molecular weight 117, also referred to as “trimethylglycine”), γ-butyrobetaine (145), homarin (137), trigonelin (137), carnitine (161) Homoserine betaine (161), valine betaine (159), lysine betaine (188), ornithine betaine (176), alanine betaine (117), stachydrin (185) and glutamate betaine (189). N-trialkyl substitution of an amino acid is mentioned. As amino acids, glycine (molecular weight 75), alanine (89), serine (105), threonine (119), valine (117), methionine (149), cysteine (121), proline (same) 115), lysine (same as 146), histidine (same as 155), arginine (same as 174) and derivatives thereof. Among these, betaine compounds are preferable, and trimethylglycine is more preferable from the viewpoint of more surely slowing the expansion speed of the recording medium after printing and preventing clogging of the ink discharge nozzles. A zwitterionic compound is used individually by 1 type or in combination of 2 or more types, may be synthesize | combined by a conventional method and may obtain a commercial item. As a commercially available product, for example, aminocoat (manufactured by Asahi Kasei Chemicals Corporation) can be used as trimethylglycine.

  The molecular weight of the zwitterionic compound is preferably 100 to 250. If the molecular weight is less than 100, the tendency to increase the viscosity difference at 10 ° C. to 40 ° C. is strong, and the recording medium after printing tends to be deformed and curled easily. . On the other hand, if the molecular weight exceeds 250, the viscosity of the ink composition tends to increase with respect to the amount of the compound added to the ink composition, and deformation such as curling occurs on the recording medium after printing. In this case, even if the recording medium is completely dried, the deformation tends to be difficult to be solved.

  From the viewpoint of suppressing the expansion speed of the recording medium after printing, and from the viewpoint of preventing clogging of the ink discharge nozzles in the inkjet head, the ink composition contains 10 to 40 mass of the zwitterionic compound with respect to the total amount. % Content is preferable, and 10 to 25% by mass is more preferable. When the content is less than 10% by mass, it is difficult to suppress the expansion rate, and when it exceeds 40% by mass, it is difficult to prevent the clogging.

  The viscosity of the ink in the temperature range of 10 ° C. to 40 ° C. is affected by the temperature characteristics of the colorant, humectant, solvent, etc. contained in the ink. Among these, the influence of the humectant is particularly great, and the viscosity at 10 ° C. is likely to increase and the viscosity at 40 ° C. is likely to decrease depending on the type, addition amount, and content ratio of the humectant. In the present specification, the fact that the difference in viscosity at 10 ° C. to 40 ° C. is smaller is described as being excellent in the viscosity characteristics depending on the temperature of the ink.

  The ink composition according to the present embodiment has the following moisturizing properties (A) and (B) from the viewpoint of maintaining an appropriate balance of curling, cockling suitability, back-through suitability, clogging suitability, and viscosity characteristics depending on ink temperature. It is preferable to include at least one moisturizing agent selected from the group consisting of agents. Here, the humectant of (A) is at least one compound selected from the group consisting of glycerin, 1,2,6-hexanetriol, diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol. ) Is at least one compound selected from the group consisting of trimethylolpropane and trimethylolethane.

The moisturizing agent (A) is particularly effective for suppressing clogging and also has an effect for suppressing curling and cockling. However, the material is inferior in penetrability due to its excellent permeability to a recording medium. Glycerin and triethylene glycol are preferred as the humectant of (A) from the viewpoint of more effectively and surely achieving the above effects.
The moisturizing agent (B) is particularly effective for suppressing clogging, and is a substance having excellent penetration-throughability since it has a permeation suppressing effect. From the viewpoint of more effectively and surely achieving these effects, trimethylolpropane is preferred as the humectant of (B).
The humectants of (A) and (B) have a large viscosity difference between 10 ° C. and 40 ° C. of the substance, so that as the content in the ink composition increases, the viscosity characteristics due to temperature are greatly affected. The ink composition also has a large viscosity difference at 10 ° C to 40 ° C.

When the ink composition according to the present embodiment contains the moisturizing agent (A) and / or (B) in addition to the zwitterionic compound, the curling suitability, cockling suitability, see-through suitability, and clogging suitability From the viewpoint, the total content of the zwitterionic compounds (A) and (B) is preferably 10% by mass to 40% by mass with respect to the total amount of the ink composition.
In addition, regarding the humectant and the zwitterionic compound (A) and (B), the mass ratio of the contents is (A) :( B) :( zwitterionic compound) from the viewpoint of exerting the above effects in a balanced manner. = (1.0) :( 0.1-1.0) :( 1.0-3.5) is preferable. When the mass ratio of the humectant of (B) to the humectant selected from the group of (A) (referred to as “(A) humectant” hereinafter the same) is larger than the above, curl suitability and cockling. The suitability decreases, and if it is decreased, the strike-through aptitude decreases. When the mass ratio of the zwitterionic compound to the humectant of (A) is larger than the above, the clogging suitability is lowered, and when it is reduced, the curling suitability and the cockling suitability are lowered.

  In addition, the ink composition according to the present embodiment is used for the purpose of preventing clogging in the vicinity of the nozzle of the inkjet head, appropriately controlling the permeability and bleeding of the ink to the recording medium, and imparting the drying property of the ink. It is preferable to contain a water-soluble organic solvent. From the above viewpoint, the water-soluble organic solvent preferably contains 1,2-alkanediol and / or glycol ether. Specific examples of 1,2-alkanediol include 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, and 4-methyl-1,2-pentanediol. Specific examples of the glycol ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether. Ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol mono-n-butyl ether, 1-methyl-1-methoxybutanol, propylene Recall monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, di Examples include propylene glycol mono-n-propyl ether and dipropylene glycol mono-iso-propyl ether. In addition to the above, 2-pyrrolidone, N-methyl-2-pyrrolidone and the like can also be used as the water-soluble organic solvent. These water-soluble organic solvents can be used singly or in combination of two or more, and 1 mass in the ink composition from the viewpoint of ensuring appropriate physical properties (such as viscosity) of the ink, ensuring print quality, and reliability. % To 50% by mass is preferable.

  Furthermore, the ink composition preferably contains a surface tension adjusting agent in order to control the wettability of the ink to the recording medium and to obtain the permeability to the recording medium and the printing stability in the ink jet recording method. As the surface tension adjusting agent, acetylene glycol surfactants and polyether-modified siloxanes are preferable. Examples of acetylene glycol-based surfactants include Surfynol 420, 440, 465, 485, 104, STG (above, Air Products, product name), Olfine PD-001, SPC, E1004, E1010 (above, day). Shinken Chemical Co., Ltd., product name), acetylenol E00, E40, E100, LH (above, Kawaken Fine Chemicals Co., Ltd., product name). Examples of the polyether-modified siloxanes include BYK-346, 347, 348, and UV3530 (Bic Chemie product). These may be used alone or in combination of two or more in the ink composition, and are included so that the surface tension of the ink composition is preferably adjusted to 20 mN / m to 40 mN / m, preferably 0 in the ink composition. .1% by mass to 3.0% by mass.

  If necessary, a pH adjuster, a complexing agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, an antiseptic / antifungal agent, and the like can be added to the ink composition. As the pH adjuster, for example, alkali hydroxides such as lithium hydroxide, potassium hydroxide, sodium hydroxide and / or alkanolamines such as ammonia, triethanolamine, tripropanolamine, diethanolamine, monoethanolamine are used. it can. In particular, it is preferably adjusted to pH 6 to 10 including at least one pH adjusting agent selected from alkali metal hydroxide, ammonia, triethanolamine, and tripropanolamine. When the pH is out of this range, there is an adverse effect on the material constituting the ink head printer, and the clogging recovery property tends to deteriorate. Examples of the complexing agent include aminopolycarboxylic acids such as ethylenediaminetetraacetic acid and salts thereof (for example, sodium salt and ammonium salt).

  The ink composition according to this embodiment preferably contains a pigment for the purpose of image formation and printing. As the pigment used in the ink composition according to this embodiment, any of known inorganic pigments and organic pigments can be used. Examples of such pigments include pigment yellow, pigment red, pigment violet, pigment blue, and pigment black described in the Color Index, as well as phthalocyanine, azo, anthraquinone, azomethine, and condensed rings. Examples thereof include pigments of the type. Further, organic pigments such as yellow No. 4, No. 5, 205, 401; orange No. 228, 405; blue No. 1, 404, carbon black, titanium oxide, zinc oxide, zirconium oxide, iron oxide, ultramarine , Inorganic pigments such as bitumen and chrome oxide. Examples of the color index of the pigment include C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42, 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 138, 150, 153, 155, 174, 180, 198, C.I. I. Pigment Red 1,3,5,8,9,16,17,19,22,38,57: 1,90,112,122,123,127,146,184,202, C.I. I. Pigment Bio Red 1,3,5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, C.I. I. Pigment Black 1 and 7 may be mentioned, and one or more pigments may be included in the ink composition.

  The pigment used in the present embodiment may be a resin dispersion type. The pigment of such an embodiment is a pigment dispersion liquid dispersed in an aqueous medium using a ball mill, a roll mill, a bead mill, a high-pressure homogenizer, a high-speed stirring disperser, and the like, together with a dispersant such as a polymer dispersant and a surfactant. Alternatively, a dispersibility-imparting group (hydrophilic functional group and / or salt thereof) is directly or indirectly bonded to the pigment surface via an alkyl group, an alkyl ether group, an aryl group, etc., and an aqueous medium without a dispersant The pigment composition is preferably blended in the ink composition as a pigment dispersion which is processed as a self-dispersing pigment dispersed and / or dissolved therein and dispersed in an aqueous medium.

  Examples of dispersants include polymer dispersants such as natural polymer compounds such as glue, gelatin and saponin, polyvinyl alcohols, polypyrrolidones, acrylic resins (polyacrylic acid, acrylic acid-acrylonitrile copolymer, Vinyl acetate-acrylic acid copolymer, vinyl acetate-acrylic acid ester copolymer, etc.), styrene-acrylic acid resins (styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid- Acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-alkyl acrylate copolymer, styrene-vinyl acetate-acrylic acid copolymer, etc. ), Styrene-maleic acid resins, vinyl acetate-fatty acid vinyl-ethylene Synthetic polymer compounds such as resins of tyrene copolymer and their salts, and the like, and the constitution of the copolymer may be any of random type, block type and graft type.

  Examples of surfactants used as dispersants include anionic surfactants such as fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfate esters, higher alkyl sulfonates, fatty acid amine salts, and fatty acid ammonium salts. Nonionic surfactants such as cationic surfactants, polyoxyalkyl ethers, polyoxyalkyl esters, sorbitan alkyl esters and the like can be mentioned.

  Of these dispersants, water-insoluble resins are particularly preferable. Specifically, the water-insoluble resin is composed of a block copolymer resin of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and contains at least a monomer having a salt-forming group. A resin having a solubility in 100 g of water at 25 ° C. of less than 1 g later is preferred. Examples of the monomer having a hydrophobic group include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl. Methacrylic acid esters such as methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, vinyl esters such as vinyl acetate, vinylcyan compounds such as acrylonitrile and methacrylonitrile, styrene, α- Methylstyrene, vinyltoluene, 4-t-butylstyrene Emissions, chlorostyrene, vinyl anisole, aromatic vinyl monomers such as vinyl naphthalene. These can be used individually by 1 type or in mixture of 2 or more types. Examples of the monomer having a hydrophilic group include polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, and ethylene glycol / propylene glycol monomethacrylate. These may be used alone or in combination of two or more. be able to. Examples of the monomer having a salt-forming group include acrylic acid, methacrylic acid, styrene carboxylic acid, and maleic acid, and these can be used alone or in combination of two or more. Furthermore, a macromonomer such as a styrene macromonomer or a silicone macromonomer having a polymerizable functional group at one end, or other monomers can be used in combination.

  This water-insoluble resin is preferably used as a salt neutralized with a tertiary amine such as ethylamine or trimethylamine, or an alkali neutralizer such as lithium hydroxide, sodium hydroxide, potassium hydroxide or ammonia, and has a weight average molecular weight of 10,000. About ˜150,000 is preferable from the viewpoint of stably dispersing the pigment.

  A self-dispersing pigment that can be dispersed and / or dissolved in water without a dispersant is, for example, an active species having a dispersibility-imparting group or a dispersibility-imparting group by applying a physical treatment or a chemical treatment to the pigment. It is produced by bonding (grafting) to the surface of the pigment. Examples of the physical treatment include vacuum plasma treatment. Examples of the chemical treatment include a wet oxidation method in which the pigment surface is oxidized with an oxidizing agent in water, and a method in which a carboxyl group is bonded via a phenyl group by bonding p-aminobenzoic acid to the pigment surface. it can. Since the ink composition containing the self-dispersing pigment does not need to contain the above-mentioned dispersant to be contained for dispersing a normal pigment, there is almost no foaming due to the reduction of the defoaming property caused by the dispersant. It is easy to prepare an ink having excellent ejection stability. In addition, since a significant increase in viscosity due to the dispersant can be suppressed, a larger amount of pigment can be contained, the printing density can be sufficiently increased, or handling becomes easy. Because of these advantages, the self-dispersing pigment is particularly effective for black ink compositions that require a high concentration, and the black ink composition used as the ink composition of the present embodiment has no dispersant. It is preferable that at least a self-dispersing pigment that can be dispersed and / or dissolved in water is contained.

  In the present embodiment, a self-dispersing pigment that is surface-treated by oxidation treatment with hypohalous acid and / or hypohalite or ozone is preferable from the viewpoint of high color development. Commercially available products can also be used as self-dispersing pigments. Examples of such commercially available products include Microjet CW-1 (trade name; manufactured by Orient Chemical Industry Co., Ltd.), CAB-O-JET200, CAB. -O-JET300 (the above-mentioned brand name; Cabot company make) can be illustrated.

  These pigments preferably have a volume average particle diameter in the range of 50 nm to 200 nm from the viewpoint of storage stability of the ink and prevention of nozzle clogging. These volume average particle diameters can be obtained by particle diameter measurement using a Microtrac UPA150 (manufactured by Microtrac) or a particle size distribution analyzer LPA3100 (manufactured by Otsuka Electronics Co., Ltd.).

  These pigments are preferably contained in the ink composition in a range of 6% by mass or more. If the content is less than 6% by mass, the print density (color developability) may be insufficient. Moreover, the upper limit of the content is not specifically limited, For example, content may be 25 mass% or less. When the content is larger than 25% by mass, there may be a problem in reliability such as nozzle clogging or unstable discharge.

The ink composition according to the present embodiment preferably contains a resin emulsion from the viewpoint of improving fixability to a recording medium. The resin emulsion preferably contains resin particles having a minimum film forming temperature of less than 20 ° C. By using a resin emulsion containing resin particles having a minimum film forming temperature of less than 20 ° C., the resin particles are formed into a film at an ambient temperature under a use environment that is usually 20 ° C. or higher. Improves fixing properties and abrasion resistance on recording media.
Here, the minimum film-forming temperature is measured as follows. First, a resin emulsion is applied to a thickness of 0.3 mm on a stainless steel plate of a temperature gradient test apparatus. Immediately after application, the basket containing silica gel is placed on a plate and covered with a transparent plastic lid. After the coating film has dried, the temperature at the boundary between the uniform continuous film portion and the cloudy portion is read to obtain the minimum film forming temperature.

  These resin emulsions contain one or more resin particles selected from the group consisting of acrylic resins, methacrylic resins, vinyl acetate resins, vinyl chloride resins, and styrene-acrylic resins. Is preferred. These resins may be used as a homopolymer or may be used as a copolymer, and any of a single-phase structure and a multiphase structure (core-shell type) can be used.

Furthermore, at least one of the resin emulsions contained in the ink composition used in the present embodiment is blended in the ink composition in the form of an emulsion of resin particles obtained by emulsion polymerization of unsaturated monomers. It is preferable. Even if the resin particles are added alone to the ink composition, the dispersion of the resin particles may be insufficient. Therefore, the emulsion form is preferable for the production of the ink composition. The emulsion is preferably an emulsion of acrylic resin particles, that is, an acrylic emulsion, from the viewpoint of the storage stability of the ink composition.
An emulsion of resin particles (such as an acrylic emulsion) can be obtained by a known emulsion polymerization method. For example, an unsaturated monomer (such as an unsaturated vinyl monomer) can be obtained by emulsion polymerization in water in which a polymerization initiator and a surfactant are present.

  Examples of unsaturated monomers include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyl cyanide monomer monomers that are generally used in emulsion polymerization. , Halogenated monomers, olefin monomers, and diene monomers.

  More specifically, as an unsaturated monomer, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate Acrylates such as octyl acrylate, decyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n -Amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate , Methacrylates such as 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate; vinyl esters such as vinyl acetate; vinyl such as acrylonitrile, methacrylonitrile Cyanide compounds; halogenated monomers such as vinylidene chloride and vinyl chloride; aromatic vinyl monomers such as styrene, α-til styrene, vinyl toluene, 4-t-butyl styrene, chlorostyrene, vinyl anisole, vinyl naphthalene; ethylene Olefins such as propylene; dienes such as butadiene and chloroprene; vinyls such as vinyl ether, vinyl ketone and vinyl pyrrolidone. Nyl monomer; unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; acrylamides such as acrylamide, methacrylamide and N, N′-dimethylacrylamide; 2-hydroxyethyl acrylate, 2 -Hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxyl group-containing monomers such as 2-hydroxypropyl methacrylate. These may be used alone or in combination of two or more.

  A crosslinkable monomer having two or more polymerizable double bonds can also be used as the unsaturated monomer. Examples of the crosslinkable monomer having two or more polymerizable double bonds include polyethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4-acryloxypropyloxyphenyl) propane, 2,2 ′ -Diacrylate compounds such as bis (4-acryloxydiethoxyphenyl) propane; Triacrylate compounds such as trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate Tetraacrylate compounds such as ditrimethylol tetraacrylate, tetramethylol methane tetraacrylate, pentaerythritol tetraacrylate; hexaacrylate compounds such as dipentaerythritol hexaacrylate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol di Methacrylate, 1,3-butylene glycol dimethacrylate, 1,4 butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate , 2, 2 Dimethacrylate compounds such as' -bis (4-methacryloxydiethoxyphenyl) propane; trimethacrylate compounds such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; methylenebisacrylamide; divinylbenzene. These may be used alone or in combination of two or more.

  In addition to the polymerization initiator and surfactant used in emulsion polymerization, a chain transfer agent, further a neutralizing agent, and the like may be used according to a conventional method. In particular, the neutralizing agent is preferably ammonia or an inorganic alkali hydroxide such as sodium hydroxide or potassium hydroxide.

  In the present embodiment, the resin emulsion contains 1 resin particle in the ink composition from the viewpoint of more effectively obtaining the ink-appropriate properties of the ink composition, reliability (clogging, ejection stability, etc.), fixability, and the like. It is preferable to contain so that it may become the range of 10 mass%-10 mass%.

  The volume average particle diameter of the resin emulsion contained in the ink composition is preferably 5 nm to 400 nm, and preferably 50 nm to 200 nm, from the viewpoints of dispersion stability and fixability of the resin particles in the ink composition. Is more preferable. The volume average particle diameter is measured using, for example, a Coulter counter N4 (trade name, manufactured by Coulter Inc.).

  According to the ink jet recording apparatus and the ink jet recording method of the present embodiment, it is possible to slow the expansion speed of the recording medium that may occur after printing while preventing the head from rubbing by applying tension. This is because when the ink composition contains a zwitterionic compound, the zwitterionic compound enters the part where the bond such as hydrogen bond between the fibers is broken by printing on the recording medium, and the bond between the fibers is reduced. This is thought to be to some extent.

That is, the recording medium such as plain paper maintains its shape because the fibers are bonded by hydrogen bonding or the like. When printing on the recording medium, water or the like contained in the ink composition breaks the bond between the fibers. If tension is applied to the recording medium in this state, it is considered that the recording medium is deformed (elongated or greatly deformed) in one direction. However, according to the present invention, the zwitterionic compound in the ink composition enters between the fibers and retains the bonds between the fibers in the recording medium to some extent. It is estimated that rapid expansion) can be suppressed. However, the factor that slows the expansion speed is not limited to this.
From this point of view, when the direction of applying the tension of the recording medium is set to a direction orthogonal to the arrangement direction of the fibers such as roulose, the effect of maintaining the bonding between the fibers can be more effectively exhibited. It is possible to reduce the difference in expansion rate from the case where tension is applied in the direction parallel to the fiber arrangement direction. Therefore, the ink jet recording apparatus and the ink jet recording method of the present embodiment become more useful by setting the direction in which the tension is applied to a direction orthogonal to the fiber arrangement direction.

Further, when the expansion speed of the recording medium is slowed, the extent to which the portion of the recording medium to be printed is shifted due to the expansion is also reduced. As a result, problems such as ink landing position misalignment and ruled line misalignment on the recording medium are alleviated, and print quality can be improved.
Further, conventionally, when the magnitude of the tension applied to the recording medium is reduced, the recording medium has a high expansion speed, so that the recording medium is bent, and the head is rubbed, and wrinkles, landing deviation, etc. are likely to occur. It was. However, according to the present embodiment, since the expansion speed of the recording medium is slow, even if the applied tension is small, bending is hardly caused.

In addition, when printing on a recording medium is printing of a pattern with local shading, conventionally, there is a possibility that uneven expansion occurs between a printed dark portion and a thin portion of the recording medium. When such unevenness of expansion occurs, the recording medium is clogged inside the recording apparatus (paper jam), or wrinkles occur on the recording medium, resulting in a decrease in print quality. However, according to the present embodiment, by reducing the expansion speed in the dark portion of printing, it is possible to suppress the uneven expansion between the thin portion of printing and thus preventing the occurrence of paper jam and wrinkles. The print quality can be improved from such a viewpoint.
Furthermore, in this embodiment, since printing is performed while applying tension to the recording medium, it is not necessary to suck the recording medium from the back side of the printing surface, which is advantageous from the viewpoint of cost and size reduction.

  The recorded matter according to the present embodiment is obtained by recording by the ink jet recording method. Since this recorded matter is obtained by the ink jet recording method according to the present embodiment, the expansion speed after printing is slowed down, so that head rubbing, ink landing position deviation, and ruled line deviation are suppressed. It is. In addition, since clogging is also suppressed, the ink composition lands on the recording medium as desired, resulting in a recorded matter on which an image with little missing dots is formed. In addition, this recorded matter is excellent in the safety and stability of the ink, and always achieves the same recording quality for various recording media regardless of the operating temperature. Has ring suitability, back-through suitability, and duplex printing suitability.

  According to the ink jet recording apparatus and the ink jet recording method of the present embodiment, by using an ink containing a zwitterionic compound, it is possible to slow the expansion speed of a recording medium that may occur after printing. Further, by applying a tension corresponding to the expansion of the recording medium that can occur even when the ink is used to the recording medium based on the expansion / contraction parameter, the recording medium may be excessively warped or wrinkled. This is convenient because it can be avoided without applying a sufficient tension. Since the expansion of the recording medium that occurs during printing is applied with a tension corresponding to the elongation, damage to the recording medium and abrupt expansion (due to the application of tension) can be avoided.

As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said this embodiment. The present invention can be variously modified without departing from the gist thereof. For example, the present embodiment relates to a line type ink jet recording apparatus, but the ink jet recording method and ink jet recording apparatus of the present invention may relate to a serial type ink jet recording apparatus that performs printing in a plurality of passes. In particular, those having a head arrangement in which ink discharge nozzles are arranged for each rotation distance of the driving roller to correct the periodic deviation of the rollers cause a time difference from the start to the completion of printing on the recording medium. For this reason, the recording medium is easily expanded. Therefore, it is preferable to employ the ink jet recording method and the ink jet recording apparatus of the present invention for those having such a configuration because the effect of suppressing the expansion speed according to the present invention can be utilized more effectively.
Further, the platen unit may be provided with a conveyance belt for assisting conveyance of the recording medium.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these Examples.

[Preparation of colorant]
(Pigment dispersion B1)
100 g of commercially available carbon black Color Black S170 (trade name: manufactured by Degussa Huls) was mixed with 1 kg of water and pulverized by a ball mill using zirconia beads. 1400 g of sodium hypochlorite (effective chlorine concentration 12%) was added dropwise to the pulverized stock solution, reacted for 5 hours while pulverizing with a ball mill, and further boiled for 4 hours with stirring to perform wet oxidation. The obtained dispersion stock solution was filtered with glass fiber filter paper GA-100 (trade name: manufactured by Advantech Toyo Co., Ltd.) and further washed with water. The obtained wet cake was redispersed in 5 kg of water, desalted and purified with a reverse osmosis membrane until the electric conductivity reached 2 mS / cm, and further concentrated until the pigment concentration reached 20% by mass to obtain pigment dispersion B1 Was prepared.
The volume average particle size of the pigment in this dispersion was measured by particle size distribution measurement using Microtrac UPA150 (manufactured by Microtrac), and found to be 110 nm.

(Pigment dispersion B2)
The pigment dispersion B1 obtained above was dried under reduced pressure at 40 ° C. for 3 days to remove moisture. The obtained paste was weighed into a round bottom flask, triethylene glycol-mono-n-butyl ether was added so that the solid content concentration was 20% by mass, and the mixture was stirred for 24 hours using a magnetic stirrer. Subsequently, a round bottom flask containing the triethylene glycol-mono-n-butyl ether dispersion was placed in the ultrasonic cleaning tank, and the dispersion was subjected to vacuum degassing for 8 hours with an aspirator while performing ultrasonic dispersion. The inside air was completely replaced with triethylene glycol mono-n-butyl ether to obtain a pigment dispersion B2.

(Pigment dispersion Y1)
In a reaction vessel sufficiently substituted with nitrogen gas using 20 parts by mass of an organic solvent (methyl ethyl ketone), 0.03 parts by mass of a polymerization chain transfer agent (2-mercaptoethanol), a polymerization initiator, and each monomer shown in Table 1. The mixture was polymerized under stirring at 75 ° C., 0.9 part by mass of 2,2′-azobis (2,4-dimethylvaleronitrile dissolved in 40 parts by mass of methyl ethyl ketone was added to 100 parts by mass of the monomer component, and 80 ° C. For 1 hour to obtain a polymer solution.

5 parts by mass of the polymer solution obtained by drying the obtained polymer solution under reduced pressure was dissolved in 15 parts by mass of methyl ethyl ketone, and the polymer was neutralized with an aqueous sodium hydroxide solution. Furthermore, C.I. I. 15 parts by weight of Pigment Yellow 74 was added, and further kneaded with a disperser while adding water. After adding 100 parts by mass of ion-exchanged water to the obtained kneaded product and stirring, the yellow ethyl pigment having a solid content concentration of 20% by mass is removed by removing methyl ethyl ketone at 60 ° C. under reduced pressure and further removing a part of the water. An aqueous dispersion (pigment dispersion Y1) was obtained.
The volume average particle size of the pigment in this dispersion was measured by measuring the particle size distribution of Microtrac UPA150 (manufactured by Microtrac) and found to be 100 nm.

(Pigment dispersion M1)
C. I. Instead of CI Pigment Yellow 74, C.I. I. A pigment dispersion M1 was obtained in the same manner as in the preparation of the pigment dispersion Y1 except that CI Pigment Red 122 was used.
The volume average particle diameter of the pigment of this dispersion was measured by particle size distribution measurement of Microtrac UPA150 (manufactured by Microtrac), and it was 140 nm.

(Pigment dispersion C1)
C. I. Instead of CI Pigment Yellow 74, C.I. I. A pigment dispersion C1 was obtained in the same manner as in the preparation of the pigment dispersion Y1, except that CI Pigment Blue 15: 4 was used.
The volume average particle size of the pigment in this dispersion was measured by measuring the particle size distribution of Microtrac UPA150 (manufactured by Microtrac), and found to be 80 nm.

[Preparation of resin emulsion]
A resin emulsion (polymer 1) having a minimum film forming temperature of less than 20 ° C. is produced by emulsion polymerization of 20 g of acrylamide with 600 g of methyl methacrylate, 125 g of n-butyl acrylate, 30 g of methacrylic acid, and 5 g of triethylene glycol diacrylate in water. did. The volume average particle diameter of the resin particles in the emulsion was 50 nm, and the minimum film forming temperature was 10 ° C. The volume average particle diameter of the resin particles was measured using a Coulter Counter N4 (trade name, manufactured by Coulter, Inc.), and the minimum film forming temperature was measured as described above.

[Preparation of ink composition]
Each component was mixed in the ratio shown in Table 2, stirred at room temperature for 2 hours, and then filtered through a membrane filter having a pore size of 5 μm to prepare each ink composition of Production Examples 1 to 12. However, the addition amounts shown in Table 2 are all expressed as mass% concentrations, the numbers in () of the pigment dispersion indicate the solid content concentration (mass%) of the pigment, and the numbers in () of the resin emulsion. Indicates the resin particle concentration (mass%). The “remaining amount” of ion-exchanged water means adding ion-exchanged water so that the total amount of the ink composition becomes 100% by mass.

<Various evaluations>
(Test 1) Expansion speed evaluation As a printer, a PX-5800 (manufactured by Seiko Epson) with a modified mechanism so that the external controller can control the driving amount, paper feed, and carriage movement of the inkjet head unit. Used and printed (printed) on the paper (product name “Xerox P”, manufactured by Fuji Xerox Co., Ltd.) with the above ink composition at an injection amount of 12 mg / inch ² . Thereafter, while the recording medium was fixed, the carriage continued to run idle at a speed of 12 inches / s, the time when head rubbing occurred was measured, and the cockling state was determined according to the following evaluation criteria.
A: Head rubbing did not occur for 10 seconds or more.
B: Head rubbing occurred in 5 to 10 seconds.
C: Head rubbing occurred in less than 5 seconds.
The results are shown in Table 3.

(Test 2) Clogging recovery property Using PX-B500 (manufactured by Seiko Epson) as a printer, printing was continuously performed for 10 minutes, and after confirming that the ink composition was normally discharged from all nozzles The ink cartridge was removed and the recording head was removed from the head cap and left in a 40 ° C. environment for one week. After leaving, the cleaning operation was repeated until all nozzles ejected at the same level as the initial stage, and the ease of recovery was evaluated according to the following criteria.
A: Recovery equivalent to the initial level after less than 6 cleaning operations B: Recovery equivalent to the initial level after 6 to 8 cleaning operations C: Recovery equivalent to the initial level after 9 or more cleaning operations is shown in Table 3.

  DESCRIPTION OF SYMBOLS 100 ... Inkjet recording apparatus, 101 ... Recording medium, 104 ... Storage cassette, 105 ... Paper feed roller, 106 ... Paper discharge tray, 109 ... Position detection sensor, 110 ... Inkjet head, 111 ... Control part, 116, 117, 118 DESCRIPTION OF SYMBOLS 119A, 119B ... Motor, 120 ... Platen part, 140 ... Conveyance roller, 150, 152, 154 ... Discharge roller, 190 ... Inkjet head unit.

Claims (10)

Printing means for printing an ink composition containing a zwitterionic compound and 10 to 60% by mass of water on a recording medium;
A transporting means for transporting the ink composition while applying tension to the printed portion when the ink composition is printed on the recording medium by the printing means;
An inkjet recording apparatus comprising:   The inkjet recording apparatus according to claim 1, wherein the zwitterionic compound is a betaine compound having a molecular weight of 100 to 250.   The ink jet recording apparatus according to claim 1, wherein the ink composition contains 10 to 40 mass% of the zwitterionic compound with respect to the total amount thereof.   The inkjet recording apparatus according to any one of claims 1 to 3, wherein the conveying unit changes the strength of the tension to be applied in accordance with a discharge amount of the ink composition by the printing unit. . A printing step of printing an ink composition containing a zwitterionic compound and 10 to 60% by mass of water on a recording medium;
When printing the ink composition on a recording medium by the printing step, a conveying step of conveying while applying tension to the printed portion;
An inkjet recording method comprising: The inkjet recording apparatus according to any one of claims 1 to 4,
Furthermore, a control means for controlling the transport means is provided,
The control means includes
An expansion / contraction parameter that is information data related to at least one of expansion and contraction of the recording medium is transmitted, and an expansion / contraction amount determination unit that determines an expansion / contraction amount of the recording medium based on the expansion / contraction parameter;
A drive control unit that sets a tensile force corresponding to the expansion / contraction amount determined by the expansion / contraction amount determination unit to the conveying unit;
An inkjet recording apparatus comprising: The inkjet apparatus according to claim 6,
The expansion / contraction amount determination unit includes a storage unit,
The ink-jet device, wherein the storage unit stores the expansion / contraction amount corresponding to the expansion / contraction parameter for each recording medium. The inkjet apparatus according to claim 6 or 7,
The expansion / contraction parameter is an ink jet apparatus including at least one of a recording medium type, an environmental condition, printing information, an ink type, and cartridge information. The inkjet recording method according to claim 5,
The conveying step is
The amount of expansion / contraction of the recording medium is determined based on an expansion / contraction parameter which is information data related to expansion / contraction of at least one of expansion and contraction of the recording medium, and the tensile force is set based on the determination result An ink jet recording method. The inkjet recording method according to claim 9, wherein
The ink jet recording method, wherein the expansion / contraction parameter includes at least one of a recording medium type, an environmental condition, printing information, an ink type, and cartridge information.