JP2005206837A - Inkjet recording method and ink for inkjet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method which can improve the ink-discharging property of a head by controlling the bubbles which are formed in or mixed into the passage in the inkjet head of an inkjet system using thermal energy. <P>SOLUTION: The objective of this invention for an inkjet recording method by which a recording is carried out by giving the thermal energy to the ink to form the bubbles and discharge the ink is achieved by the inkjet recording method and an ink for inkjet where the cloud point (T) of a liquid obtained by removing pigments from the ink, the temperature T<SB>0</SB>before bubble formation at a place where the bubbles are formed and the temperature T<SB>1</SB>of the ink portion surrounding the bubbles and including the portion attaching to the bubbles satisfy the relationship, T<SB>0</SB><T<T<SB>1</SB>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording method and ink jet ink, and more particularly to an ink jet recording method capable of improving ejection response and ink droplet characteristics, ink jet ink, an ink tank having the ink jet ink, and a cartridge with a head.

  Conventionally, in ink jet recording, various studies have been made to obtain good ink ejection. In particular, various methods such as nozzle design and ink design have been proposed with respect to methods for preventing ejection defects caused by bubbles remaining in the head nozzle or mixed in. Japanese Patent Application Laid-Open No. 2002-80768 (Patent Document 1) discloses a method of improving the discharge property after stopping discharge for a certain time by including an antifoaming agent such as siloxane in the ink composition in the piezoelectric discharge method. ing.

  Various additives have been studied to improve and improve ink characteristics, and are highly stable at the temperature before and under the operating environment of the recording device when contained in an ink mainly composed of water. An additive having is selected. There is a surfactant as one of the additives, and various functions of the surfactant are used in ink jet ink. Typically, a nonionic surfactant is used as an ink component in order to ensure the desired penetrability of the ink into a recording medium such as paper. In this case, the cloud point is preferably 60 ° C. or higher so that a desired function can be exhibited in the operating environment of the ink jet recording apparatus (Japanese Patent Laid-Open No. 2001-354880: Patent Document 2). ).

On the other hand, ink jet heads that use thermal energy to cause film boiling and apply ink in the flow path to the recording medium from the discharge ports have also been put into practical use, and many inventions for improving the discharge performance Has been proposed and implemented.
JP 2002-80768 A JP 2001-354880 A JP-A-8-034124

  In an ink jet system in which film boiling is caused by using thermal energy and ink in a flow path is applied to a recording medium from a discharge port, the film boiling occurs on the surface where heat from a heating element (heater) acts on the ink. The process of bubble generation, growth and disappearance is repeated in the flow path every time a discharge signal is applied. Ink is applied to the recording medium in the form of liquid droplets from the discharge port under pressure accompanying the generation of bubbles. In this method, some of the bubbles generated by heating from the heater remain in the flow path, spontaneous generation of bubbles under the operating environment temperature of the device, and bubbles enter the flow path from the liquid chamber. If this occurs, it will affect the pressure transmission to the ink when bubbles are generated on the heater surface, resulting in a decrease in ejection signal responsiveness, deformation of the droplet shape, defective ejection of the droplet, and droplets on the recording medium. In some cases, it may cause a decrease in ink ejection characteristics, such as a decrease in landing accuracy. Regarding the spontaneous generation of bubbles under the operating environment temperature of the device, if the number of ejections per unit time increases and the temperature of the ink in the flow path rises, the solubility of dissolved gas in the ink will increase. By reducing, fine bubbles are generated, and when these bubbles grow or combine, they may become large bubbles that affect the ejection characteristics. Therefore, it is important to suppress the spontaneous generation of bubbles by suppressing the unnecessary increase in the ink temperature in the flow path by causing the bubble process to function functionally.

  As a method for preventing bubbles from remaining or mixed in the liquid chamber or the flow path, there is a method in which the defoaming agent mentioned above is contained in the ink. The antifoaming agent has at least one of the function of suppressing the generation of bubbles and the function of facilitating the disappearance of the bubbles that have already occurred, and various substances are studied as antifoaming agents and antifoaming agents for ink-jet inks. Has been. However, it is possible to eliminate the bubbles in the flow path to some extent by adding an antifoaming agent or an antifoaming agent to the ink, but the solubility of substances that are studied as an antifoaming agent or an antifoaming agent is often low. When contained in the ink at a content that produces an antifoaming effect, the antifoaming agent and antifoaming agent are separated from the ink, and adhere to the ink contact member and around the ink ejection port, which causes ink ejection failure. It may be a new cause. In particular, in the bubble jet method using thermal energy, the foaming agent or antifoaming agent may adhere to the heater surface, which may damage the drive system and cause ink droplet ejection failure.

  On the other hand, the cloud point of the additive contained in the ink is selected from the viewpoint of ensuring the solubility of the additive in the ink in the operating environment of the recording apparatus, and is set to be equal to or higher than the operating environment temperature of the recording apparatus. That is, the conventional technology considering such a cloud point is not only one that actively uses the cloud point of the additive to improve the ink discharge characteristics, but the conventional technology has a cloud point of a liquid medium containing the additive. There is no suggestion regarding the characteristics.

  Therefore, an object of the present invention is to improve the ink ejection characteristics of the head by controlling the state of bubbles generated in the flow path or mixed into the flow path in an ink jet head using an ink jet method that uses thermal energy. An object of the present invention is to provide a novel ink that can be used, and to provide an ink jet recording method using the same. Furthermore, the present invention provides an ink tank using such ink and a cartridge having an ink jet head portion.

In the ink jet recording in which ink is applied with thermal energy to generate bubbles and the ink is discharged from the discharge port, in order to improve the discharge property of the ink, the bubbles generated for the discharge are the cause. Focusing on the accumulation of the remaining bubbles in the discharge port, investigations were made to suppress the generation of the remaining bubbles and further to suppress the accumulation of remaining bubbles in the discharge port. In the process, when focusing on the gas-liquid interface between the bubbles generated in the discharge port and the ink in contact with the bubbles, the ink in which the color material is contained in the liquid medium having a cloud point is applied to the ink by applying thermal energy to the bubbles. When used in an inkjet recording method in which recording is performed by ejecting ink from a discharge port, the cloud point (T) of the liquid obtained by removing the color material from the ink, and formation of the bubble in the portion where the bubble is generated The relationship between the three temperature conditions of the previous temperature T ₀ and the temperature T ₁ of the portion of the ink that includes and surrounds the bubble is important, and adjusts these relationships Thus, it has been found that there is a phenomenon in which the remaining bubbles are suppressed and the accumulation of the remaining bubbles in the discharge port can also be suppressed. The present invention has been completed from such new findings.

That is, according to a first aspect of the ink jet recording method of the present invention, in the ink jet recording method in which recording is performed by applying thermal energy to the ink to generate bubbles and ejecting the ink from the ejection port, the coloring material is extracted from the ink. The cloud point (T) of the removed liquid, the temperature T ₀ before the formation of the bubble in the portion where the bubble is generated, the temperature T ₁ of the portion of the ink that includes the portion that is in contact with the bubble and surrounds the bubble, This relationship is T ₀ <T <T ₁ .

  According to a second aspect of the ink jet recording method of the present invention, in the ink jet recording method in which recording is performed by causing film boiling in the ink and discharging ink droplets from the discharge port, the liquid obtained by removing the color material from the ink is used. A cloud point (T) is in the range of 50 ° C. or more and 60 ° C. or less.

  The ink-jet ink of the present invention is an ink-jet ink that contains water, an aqueous medium, a color material, and a surfactant and is provided with thermal energy that causes film boiling, and the color material is removed from the ink. An ink-jet ink having a clouding point (T) of a liquid in a range of 50 ° C. or higher and 60 ° C. or lower.

  The ink tank of the present invention is an ink tank that contains water, an aqueous medium, a coloring material, and a surfactant, and that stores ink for inkjet that is given thermal energy that causes film boiling. The ink tank is characterized in that the cloud point (T) of the liquid excluding the material is in the range of 50 ° C. or more and 60 ° C. or less.

  The cartridge of the present invention includes a storage unit that stores ink containing water, an aqueous medium, a coloring material, and a surfactant, and an electrothermal conversion element for applying thermal energy that causes film boiling of the ink. An ink jet head section, wherein a cloud point (T) of a liquid obtained by removing a color material from the ink is in a range of 50 ° C. or higher and 60 ° C. or lower.

  According to the present invention, the cloud point of the liquid obtained by removing the color material from the ink is the temperature change region associated with the bubble generation, growth and disappearance bubble process in the flow path where the heat from the heater in the head acts. The temperature is set to be higher than the lower limit, and the portion in contact with the ink bubbles is locally heated to a temperature equal to or higher than the cloud point, and the characteristic change in the portion in contact with the ink bubbles [typically, As a whole, a mixed state of an aqueous part and an oily part (hydrophobic part) is generated from the aqueous state, and the process of bubble generation, growth and extinction can be advanced in a good state, and the discharge signal responsiveness is improved. It is possible to achieve improved ink ejection characteristics such as maintaining the droplet shape, preventing droplet ejection failure, and improving droplet landing accuracy on the recording medium.

  In addition, according to the present invention, the bubble process including the generation, growth, and disappearance process of the bubble started by applying the discharge signal to the heater is functionally advanced, and further, the interface between the bubble and the ink is formed. Due to the function that the change in the characteristics of the ink adjacent to the bubble reduces the temperature transferability in the adjacent bubble, an unnecessary increase in the ink temperature in the entire flow path can be suppressed. It is also possible to suppress the spontaneous generation of bubbles that may cause

  Furthermore, even when bubbles are mixed into the flow path from the liquid chamber, etc., the function of the bubble process by setting the cloud point of the liquid obtained by removing the color material from the ink to a temperature higher than the lower limit of the temperature change region during ink ejection The influence of the mixed bubbles can be reduced or eliminated by the general progress.

  In the case of the bubble jet method in which ink is discharged from the discharge port by generating thermal bubbles in the ink, the defoaming speed until the bubbles disappear and finally disappear is the ink in the flow path. It is often designed to be left to the natural diffusion of heat into or into the material making up the flow path. In order to increase the defoaming speed, it has also been proposed to rapidly cool the inside of the flow path. However, the device, system, and electric power for driving it are further required, and the cost for cooling increases. Therefore, it is difficult to apply to a head or a recording apparatus in which the price and running cost are suppressed. In contrast, in the system according to the present invention, the defoaming speed can be improved and the defoaming process can be progressed with a simple configuration of adjusting the cloud point of the liquid obtained by removing the color material from the ink. The above problems due to the use of the cooling device do not occur.

  The inventors of the present invention have achieved the mechanism of the present invention by reducing the interface forming ability of the liquid showing a cloud point when the liquid showing the cloud point forming the gas-liquid interface reaches a temperature exceeding the cloud point. The antifoaming property is expected to be exhibited, and therefore the cloud point of the liquid obtained by removing the color material from the ink is expected to exhibit the effect of solving the above problem.

  The ink used in the method of the present invention is the generation, growth and disappearance of bubbles due to heat generation on the surface in the flow path where the heat from the heater of the ink jet head (hereinafter referred to as the head when abbreviated) acts on the ink. It has a cloud point of the liquid obtained by removing the color material from the ink at a temperature higher than the lower limit of the temperature change region of the ink in the process. The reason why good ink ejection characteristics can be obtained when this ink is used is that the part of the ink that is in contact with the bubble through the process of bubble generation, growth and disappearance, especially the interface of the ink in contact with the bubble is While it is in progress, it is locally heated to a temperature above its cloud point, causing a change in the properties of the liquid that exhibits the cloud point near the interface, and the process of bubble growth to disappearance (defoaming) proceeds well. It is considered that this is because an effect such as formation of a good droplet from the discharge port and suppression of generation of remaining bubbles can be obtained. That is, according to the present invention, the cloud point of the liquid obtained by removing the color material from the ink is set to a temperature higher than the lower limit of the temperature change region of the ink in the flow path of the head, and the ink interface in contact with the bubbles is the cloud point or higher. Technology that uses the characteristic change caused by local heating to a certain temperature, and sets the cloud point of the additive above the operating environment temperature of the recording device to ensure the solubility of the additive in ink Is distinctly different.

  For example, in Patent Document 2, the nonionic surfactant having a cloud point of 60 ° C. or higher is selected as the nonionic surfactant dissolved in the ink at the temperature of the ink in the operating environment of the recording apparatus. This does not include the technical idea of setting the cloud point of the ink itself.

The ink used in the present invention includes at least an aqueous medium and a coloring material, and the cloud point (T) of the liquid obtained by removing the coloring material from the ink is until the generation, growth, and disappearance of bubbles when droplets are ejected in the head. The temperature is set to be higher than the lower limit of the local temperature change region of the ink in contact with the bubbles in the bubble process. The cloud point of the liquid after removing the color material from the ink is
(1) Temperature change of ink in the flow path of the head actually measured,
(2) Estimated value of temperature change obtained by correcting the measured value of temperature change by the structure of the head,
(3) T ₀ (temperature before bubble formation in a portion where bubbles are generated in the head flow path) and T ₁ (temperature in the head flow path) obtained from the value of the temperature change estimated from the head structure The temperature can be set based on the temperature of the portion of the ink that includes the portion in contact with the bubble and surrounds the bubble. The case of (2) includes, for example, a method of measuring the ink temperature at a specific position in the liquid chamber communicating with the flow path and estimating the temperature change at the time of foaming from the measured value. These measuring methods are described in JP-A-8-034124 (Patent Document 3) and the like.

  Ink designed on the basis of usage at room temperature, the ink in the flow path has a temperature of about 30 to 35 ° C. when no discharge signal is applied, and the heater has a discharge signal. When applied, the surface where the heat from the heater acts on the ink in the flow path (heater surface) instantaneously rises to a temperature of about 360-540 ° C. As the heater surface is heated, the ink in contact with the heater surface is heated to about 100 ° C., causing film boiling and bubbles. The pressure accompanying the instantaneous generation of the bubbles is applied to the ink as an initial inertial force, and the bubbles grow at an accelerated speed. In response to this, the ink is discharged as droplets from the discharge port communicating with the flow path. The temperature of the ink bubble surrounding portion (the portion including the gas-liquid interface) surrounding the bubble is raised to about 70 ° C. when the bubble is generated, and the temperature of the bubble adjacent portion of the ink is about 60 to 65 ° C. when the bubble grows. Further, the temperature drops to 60 ° C. or less along with defoaming, and drops to about 30 to 35 ° C. again by replenishing the ink on the heater surface. If the cloud point of the ink is set to a temperature higher than the lower limit of such a temperature change region of the ink, the functional progress of the bubble process and the stable maintenance of the bubble shape can be achieved, and the ink ejection characteristics are improved. It becomes possible.

  The progress of the bubble process and the temperature change of the ink are controlled by control on the recording device side such as adjustment of the pulse width and pulse interval of the electric signal applied to the heater, or adjustment of the scanning speed of the head on the recording medium. However, in the present invention, these controls are performed by changing the characteristics of the ink. By using the method of the present invention, the dependency on the control on the recording apparatus side is reduced, and the apparatus configuration and apparatus are reduced. The configuration of the control system on the side can be simplified.

  The cloud point of the liquid after removing the color material from the ink is below the temperature (for example, the maximum temperature) at which the ink in the bubble adjacent part reaches through the bubble process depending on the operating conditions of the device according to the structure of the head and the usage environment. However, when considering use in a general-purpose recording apparatus, it is preferable to set the temperature within the range of 50 ° C. or higher and 60 ° C. or lower.

The ink in the present invention is designed so that the temperature in the portion adjacent to the bubbles generated on the heater surface is equal to or higher than the cloud point of the liquid obtained by removing the color material from the ink. The temperature is lower than the cloud point in a part away from the bubble, for example, in the vicinity of the discharge port, and the droplet is discharged by setting the cloud point according to the definition (T ₀ <T <T ₁ ) according to the present invention. The influence on the characteristics and the recording characteristics on the recording medium is substantially eliminated.

  As the aqueous medium used in the ink of the present invention, water or a mixture of water and a water-soluble organic solvent can be used. Examples of water-soluble organic solvents that can be contained in the aqueous medium include amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; ethers such as tetrahydrofuran and dioxane; polyalkylenes such as polyethylene glycol and polypropylene glycol Glycols; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. alkylene glycol containing 2 to 6 carbon atoms Glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (also Lower alkyl ethers of polyhydric alcohols such as ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide, 2-pyrrolidone, Examples thereof include cyclic amide compounds such as ε-caprolactam and imide compounds such as succinimide. At least one of these can be used.

  As a method for setting the cloud point of the liquid obtained by removing the color material from the ink to a predetermined value, a method such as a method of adding a surfactant can be used.

  One type selected from known surfactants or a combination of two or more types can be used by adjusting the relationship with other components contained in the ink. Further, when the surfactant type used in the ink is nonionic, it is preferable not only because the cloud point is easily controlled, but also from the viewpoint of ink stability.

  The content of the surfactant in the ink is set so that the ink has a desired cloud point, and is selected according to the type and content of other components of the ink. Examples of the coloring material of the ink include dyes and pigments for inkjet, and the concentration in the ink is appropriately set according to the desired application.

  In addition to the above-described components, the ink includes, for example, a surfactant, a pH adjuster, a viscosity that uses functions other than urea, thiourea, or a urea derivative, and a cloud point adjusting function within a range that does not impair the effects of the present invention. You may mix | blend additives, such as a regulator, antiseptic | preservative, antioxidant, an evaporation accelerator, an evaporation inhibitor, a rust inhibitor, a fungicide, and a chelating agent.

  Further, the relationship of the present invention is established by measuring the cloud point of the liquid from which the color material has been removed from the ink containing the color material to a level at which the cloud point can be confirmed using means such as a centrifuge or filtration. In the ink jet recording method, the same effect was obtained.

  The content ratio of water in the aqueous medium in the ink used in the present invention can be selected from the range of, for example, 50 to 100% by mass, preferably 80 to 100% by mass with respect to the total amount of the aqueous medium. The content of the surfactant for adjusting the cloud point is set so as to obtain the target cloud point as described above, but is, for example, 0.1 to 10% by mass, preferably, based on the total amount of the aqueous medium. , From 0.5 to 5% by mass.

  As the color material, a dye or a pigment can be used, and particularly effective for a water-dispersed color material used by being dispersed in an aqueous medium such as a pigment. The cohesiveness of the pigment dispersed in the aqueous medium tends to be temperature-dependent. Therefore, by controlling the remaining bubbles in the ink according to the present invention, which suppresses the temperature increase in the head, the cohesiveness of the pigment dispersed in the aqueous medium is suppressed. This is because it is possible to ensure a good ejection property of ink droplets. The content of the color material in the ink can be selected from a range of 0.1 to 10% by mass, preferably 1 to 5% by mass with respect to the total amount of the ink.

  As the ink jet recording apparatus used in the present invention, a system in which thermal energy is applied to ink and ejected as droplets or the like from a discharge port, a so-called bubble jet type device is used, and a nozzle portion including a flow path and a discharge port is used. The present invention is particularly suitable for an apparatus using a multi-nozzle type head in which the size is miniaturized and arranged at high density, or a head that enables high-frequency driving.

  Specific examples of the apparatus are shown in FIGS. FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along line AB in FIG. The head 13 includes a glass, ceramic or plastic plate having a groove 14 that constitutes an ink flow path, and a heat generating substrate 15 that constitutes a heat generating element (heater) (in the drawing, a thin film laminated type configuration is shown. (It is not limited to this)). The heat generating substrate 15 is a substrate with good heat dissipation such as a protective film 16 formed of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heat generating resistor layer 18 formed of nichrome or the like, a heat storage layer 19, and alumina. 20. The ink 21 reaches the discharge port (discharge orifice) 22 and forms a meniscus 23 by the pressure P.

  When an electrical signal is applied to the aluminum electrodes 17-1 and 17-2, a region not covered with the electrode of the heating resistor layer indicated by n suddenly generates heat, and film boiling occurs in the ink 21 in contact therewith. Then, bubbles are generated and grow, and the meniscus 23 protrudes by the pressure, and the ink 21 is ejected to form ink droplets 24 from the ejection ports 22 and fly toward the recording material 25.

  FIG. 3 shows an external view of a multi-head in which a large number of heads shown in FIG. 1 are arranged. This multi-head is manufactured by adhering a glass plate 27 having multi-grooves 26 and a heat generating substrate 28 having the same configuration as that described in FIG.

  FIG. 4 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member. One end of the blade 61 is held by a blade holding member to become a fixed end, and forms a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the head 65, and in this example, is held in a form protruding in the movement path of the head 65.

  Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61 and has a configuration in which it moves in a direction perpendicular to the moving direction of the head, abuts against the ink discharge port surface, and performs capping. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding in the moving path of the head 65. The blade 61, the cap 62, and the ink absorber 63 constitute a discharge recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the ink discharge port surface.

  65 is a head that has heat generation means (for example, the heat generating substrate shown in FIG. 1) as discharge energy, and performs recording by discharging ink onto a recording material facing the discharge port surface on which the discharge ports are arranged. Reference numeral 66 denotes a carriage for mounting the head 65 and moving the head 65. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 (not shown) driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording area by the head 65 and its adjacent area can be moved.

  Reference numeral 51 denotes a paper feed unit for inserting a recording material, and 52 denotes a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the head 65, and is discharged to a paper discharge portion provided with a paper discharge roller 53 as recording progresses.

  In the above configuration, when the head 65 returns to the home position due to the end of recording or the like, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port surface of the head 65 is wiped. When capping is performed with the cap 62 contacting the ejection surface of the head 65, the cap 62 moves so as to protrude into the movement path of the head.

  When the head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the above-described wiping position. As a result, the ejection port surface of the head 65 is wiped even during this movement.

  The above movement of the head to the home position is not only at the end of recording or at the time of recovery of ejection, but also moved to a home position adjacent to the recording area at a predetermined interval while the head moves the recording area for recording, The wiping is performed with this movement.

  FIG. 5 is a diagram illustrating an example of a cartridge 45 as an ink tank that stores ink supplied to the head via an ink supply member, for example, a tube. Reference numeral 40 denotes an ink container, for example, an ink bag, which contains ink for supply, and a rubber plug 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives waste ink. The ink container preferably has an ink contact surface made of polyolefin, particularly polyethylene. The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, but is preferably used in an apparatus in which they are integrated as shown in FIG.

  In FIG. 6, reference numeral 70 denotes a recording unit (a cartridge having a head), in which an ink storage portion storing ink, for example, an ink absorber is stored, and a plurality of inks in the ink absorber are stored. It is configured to be ejected as ink droplets from a head portion 71 having an orifice. As the material of the ink absorber, it is preferable for the present invention to use polyurethane, cellulose, or polyvinyl acetal. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. The recording unit 70 is used in place of the head shown in FIG. 4 and is detachable from the carriage 66.

  Although FIG. 6 shows a configuration in which the ink storage unit (ink tank unit) and the head unit are integrated, the ink storage unit is an ink cartridge, and the ink cartridge is configured to be detachable from the head unit. It may be exchangeable for a new one.

Next, an Example and a comparative example are given and this invention is demonstrated concretely.
(Preparation of ink)
In the inks of the examples and comparative examples shown below, each component is mixed, dissolved and dispersed with sufficient stirring, and then a fluoropore filter having a pore size of 0.4 μm (trade name: manufactured by Sumitomo Electric Co., Ltd.) And pressure filtration.

Here, the ink temperature in the nozzle described in the evaluation item is a value measured by including a temperature sensor function in a heater that causes the ink to foam.
(Evaluation of ejectability 1)
Alphanumeric characters were printed using a commercially available inkjet printer BJC-4400 (trade name: manufactured by Canon Inc.) under the environment of 25 ° C. (T ₀ ) using each of the inks of the following examples and comparative examples. . In addition, an acetylene glycol-based ethylene oxide adduct was used as an additive for adjusting the cloud point in the inks of Examples and Comparative Examples. The ink temperature in the nozzle was slightly over 60 ° C. (60 ° C. <T ₁ ), and the temperature in the nozzle before starting printing was 25 ° C. (T ₀ ). In addition, the cloud point measurement of the liquid obtained by removing the color material from the ink prepared below is performed by placing the liquid obtained by removing the color material from the ink into a 100 cc beaker and heating and raising the temperature using a water bath. The temperature at which no liquid started to emulsify or become cloudy was taken as the cloud point.
(Ink of Example 1)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 30 ° C. (T) In addition, the ink of Example 1 was obtained.
(Ink of Example 2)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 60 ° C. (T). In addition, the ink of Example 2 was obtained.
(Ink of Example 3)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid not containing a colorant whose composition is adjusted so that the cloud point is 50 ° C. (T) In addition, the ink of Example 3 was obtained.
(Ink of Comparative Example 1)
20 Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) is used as a water-dispersed colorant in a liquid that does not contain a colorant whose composition has been adjusted so that the cloud point is 20 to 25 ° C. (T). The ink of Comparative Example 1 was obtained by adding mass%.
(Ink of Comparative Example 2)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition has been adjusted so that the cloud point is 65 ° C. (T). In addition, the ink of Comparative Example 2 was obtained.
(Comparison of print results)
The inks of Example 2 (T = 60 ° C.) and Example 3 (T = 50 ° C.) showed only printing and no bleeding. Ink of Example 1 (T = 30 ° C.) was slightly printed and drooled or smudged, but no dots were missing. In the ink of Comparative Example 1 (T = 20 to 25 ° C.) and Comparative Example 2 (T = 65 ° C.), only dripping or dot missing was observed. Moreover, when the same evaluation was performed using the ink obtained in Example 1 by using the color material with a centrifuge and removing the color material to a level at which the cloud point could be measured, the same evaluation as in Example 1 was performed. Also, the cloud point did not change, the print was drooled, and no blur was observed.

(Evaluation of ejection properties 2)
The inks obtained in the following Examples and Comparative Examples were used in a commercially available inkjet printer BJC-5500 (trade name: manufactured by Canon Inc.) in a 35 ° C. environment (T ₀ ), and A4 size was 100% Duty. Solid images were continuously printed and evaluated according to the following criteria. At this time, the ink temperature in the nozzle was slightly over 60 ° C. (60 ° C. <T ₁ ), and the temperature in the nozzle before starting printing was 35 ° C. (T ₀ ). Met. In addition, the cloud point measurement of the liquid obtained by removing the color material from the ink prepared below is performed by placing the ink not containing the color material in a 100 cc beaker and heating and raising the temperature using a water bath. The cloudy point was defined as the temperature at which the emulsion began to emulsify or become cloudy.
(Ink of Example 4)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition has been adjusted so that the cloud point is 40 ° C. (T). In addition, the ink of Example 4 was obtained.
(Ink of Example 5)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 60 ° C. (T). In addition, the ink of Example 5 was obtained.
(Ink of Example 6)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid not containing a colorant whose composition is adjusted so that the cloud point is 50 ° C. (T) In addition, the ink of Example 6 was obtained.
(Ink of Comparative Example 3)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 30 ° C. (T) In addition, the ink of Comparative Example 3 was obtained.
(Ink of Comparative Example 4)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 70 ° C. (T). In addition, the ink of Comparative Example 4 was obtained.
(Comparison of print results)
The inks of Example 5 (T = 60 ° C.) and Example 6 (T = 50 ° C.) can continuously print 40 sheets or more of 100% duty solid images in A4 size. I couldn't see it. The ink of Example 4 (T = 40 ° C.) could continuously print 40 sheets of 100% duty solid images in A4 size, but a non-ejection part was observed on a part of the printed matter and the ejection port was observed. Bubbles were seen. The inks of Comparative Example 3 (T = 30 ° C.) and Comparative Example 4 (T = 70 ° C.) could not continuously print 40 sheets of 100% duty solid images in A4 size. Furthermore, when the comparative example 3 and the comparative example 4 were confirmed, the discharge outlet was filled with foam.

(Evaluation of ejection properties 3)
The ink obtained in the following Examples and Comparative Examples was used in a commercially available inkjet printer P-400C (trade name: manufactured by Canon Inc.) under a 15 ° C. environment (T ₀ ), and the postcard size was 100% Duty. Solid images were continuously printed and evaluated according to the following criteria. At this time, the ink temperature in the nozzle was slightly over 60 ° C. (60 ° C. <T ₁ ), and the temperature in the nozzle before starting printing was 15 ° C. (T ₀ ). In addition, the cloud point measurement of the liquid obtained by removing the color material from the ink prepared below is performed by placing the ink not containing the color material in a 100 cc beaker and heating and raising the temperature using a water bath. The cloudy point was defined as the temperature at which the emulsion began to emulsify or become cloudy.
(Ink of Example 7)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition has been adjusted so that the cloud point is 20 ° C. (T) In addition, the ink of Example 7 was obtained.
(Ink of Example 8)
20% by weight of Cabojet300 (15% by weight aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition has been adjusted so that the cloud point is 60 ° C. (T) In addition, the ink of Example 8 was obtained.
(Ink of Example 9)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid not containing a colorant whose composition is adjusted so that the cloud point is 50 ° C. (T) In addition, the ink of Example 9 was obtained.
(Ink of Comparative Example 5)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 15 ° C. (T). In addition, the ink of Comparative Example 5 was obtained.
(Ink of Comparative Example 6)
20% by mass of Cabojet300 (15% by mass aqueous dispersion, trade name: manufactured by CABOT) as a water-dispersed colorant in a liquid that does not contain a colorant whose composition is adjusted so that the cloud point is 70 ° C. (T). In addition, the ink of Comparative Example 6 was obtained.
(Comparison of print results)
The ink of Example 8 (T = 60 ° C.) and Example 9 (T = 50 ° C.) can continuously print 40 sheets or more of 100% duty solid images in A4 size. I couldn't see it. Ink of Example 7 (T = 20 ° C.) could be printed continuously at 50 sheets or more and less than 100 sheets. In addition, the nozzles were filled with bubbles when observing the ejection openings when printing was not possible due to the total ejection failure of the nozzles. The inks of Comparative Example 5 (T = 15 ° C.) and Comparative Example 6 (T = 70 ° C.) were able to print less than 50 continuous A4 size 100% Duty solid images. At that time, when I looked at the outlet, it was full of bubbles.

It is a longitudinal cross-sectional view of the head part of an inkjet recording device. It is a cross-sectional view of the head part of an inkjet recording device. FIG. 2 is an external perspective view of a head in which the head shown in FIG. It is a perspective view which shows an example of an inkjet recording device. It is a longitudinal cross-sectional view of an ink cartridge. It is a perspective view of a recording unit.

Explanation of symbols

13 Head 14 Groove 15 Heating Substrate 16 Protective Film 17-1 Aluminum Electrode 17-2 Aluminum Electrode 18 Heating Resistor Layer 19 Heat Storage Layer 20 Substrate 21 Ink 22 Discharge Port 23 Meniscus 24 Ink Droplet 25 Recording Material 26 Multi-Groove 27 Glass Plate 28 Heat generating head 40 Ink storage part (ink bag)
42 Plug 44 Ink Absorber 45 Ink Cartridge 51 Paper Feeder 52 Paper Feed Roller 53 Paper Discharge Roller 61 Blade (Wiping Member)
62 Cap 63 Ink Absorber 64 Discharge Recovery Unit 65 Head 66 Carriage 67 Guide Shaft 68 Motor 69 Belt 70 Recording Unit 71 Head Unit

Claims (8)

In an ink jet recording method for performing recording by applying thermal energy to ink to generate bubbles and ejecting ink from ejection ports,
The cloud point (T) of the liquid obtained by removing the color material from the ink, the temperature T ₀ before the formation of the bubbles in the portion where the bubbles are generated, and the portion of the ink surrounding the bubbles including the portions in contact with the bubbles The relationship between the temperature T ₁ and the temperature T ₁ is T ₀ <T <T ₁ .   The inkjet recording method according to claim 1, wherein the ink includes water, an aqueous medium, a coloring material, and a surfactant.   The inkjet recording method according to claim 2, wherein the color material is a water-dispersed color material. The inkjet recording method according to claim ₁ , wherein T ₀ is 40 ° C. or lower and T ₁ is 60 ° C. or higher.   In an ink jet recording method for recording by causing film boiling in ink and discharging ink droplets from an ejection port, the cloud point (T) of the liquid excluding the color material from the ink is 50 ° C. or higher and 60 ° C. or lower. An inkjet recording method characterized by being in a range.   An inkjet ink containing water, an aqueous medium, a coloring material, and a surfactant, to which thermal energy that causes film boiling is applied, and having a cloud point (T) of a liquid obtained by removing the coloring material from the ink An inkjet ink characterized by being in the range of 50 ° C or higher and 60 ° C or lower.   An ink tank containing ink for ink-jet recording, which contains water, an aqueous medium, a coloring material, and a surfactant, and is provided with thermal energy that causes film boiling. The ink tank, wherein the point (T) is in a range of 50 ° C. or more and 60 ° C. or less.   A storage section for storing ink containing water, an aqueous medium, a coloring material, and a surfactant; and an inkjet head section including an electrothermal conversion element for applying thermal energy that causes film boiling of the ink. A cartridge having a cloud point (T) of a liquid obtained by removing a color material from the ink in a range of 50 ° C. or more and 60 ° C. or less.

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