JP2009178692A - Method for dispersing discharged liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for dispersing a discharged liquid which generates no precipitate during a storage period and eliminates capturing of bubbles by dispersion. <P>SOLUTION: The method for dispersing a discharged liquid which is used in an apparatus mounting a tank or a cartridge housing the discharged liquid having particles of micron order includes a first process of completely dispersing the particle precipitate part in the tank or the cartridge before using the discharged liquid in the apparatus and a second process of continuing the dispersion by lowering dispersion power during a period after the precipitate part has been removed and till the discharged liquid in the apparatus is used. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a discharge liquid dispersion method for dispersing discharge liquid (for example, ink) having micron-order particles in a tank or cartridge mounted on a droplet discharge apparatus or the like before use in the apparatus.

In general, as a discharge liquid used in a droplet discharge recording apparatus such as an ink jet recording apparatus, a liquid (ink) in which dispersed particles such as pigments are uniformly dispersed in a solvent may be used. Such ink has a property that when the printing is not performed for a long period of time or when the ink is not circulated in the ink storage unit, the dispersed particles settle due to the difference in specific gravity between the solvent and the dispersed particles. .
In such sedimentation of dispersed particles, it has been studied to provide a stirring device in order to keep the concentration constant. For example, in Patent Document 1, as a method for redispersing precipitated particles, a magnet stirrer is disposed at the bottom of the ink tank, and the stirrer in the ink tank is rotated by the rotation of the magnet stirrer to diffuse the precipitated particles. (For example, refer to Patent Document 1).
Further, an ink dispersion method by intermittent operation using a stirrer chip and a stirrer and an ink dispersion method by ultrasonic irradiation are disclosed (for example, see Patent Document 2).

Japanese Unexamined Patent Publication No. 60-110458 JP 2004-74625 A

The target of the particles in the discharge liquid to be dispersed in the above patent document is a pigment (particle size: 50 to 200 nm), but in the present invention, the target is micron order particles, and the effect can be obtained even if a dispersant is used. Therefore, in order to maintain a constant concentration, dispersion must always be performed. Discharge liquid that has micron-order particles before it is installed in a droplet discharge device of a tank or cartridge causes precipitation during the storage period. Must be distributed. However, if the storage period of the tank or the cartridge becomes long, the stirrer is buried in the discharged liquid particles, and the stirrer does not rotate even if the magnetic stirrer is rotated. Moreover, even if the stirring bar buried in the precipitation part appears from the precipitation part, there is a problem that normal stirring cannot be performed because the stirring bar stays in one place or the stirring bar jumps. Dispersion can be achieved by carrying out strong agitation in order to reliably disperse the sedimentation part, but bubbles are taken into the liquid. When the droplet ejection device is filled, trapped bubbles may become a non-ejection factor if they accumulate inside the ejection path, and further inside the head, so it is necessary to avoid rotation that traps bubbles or to quickly eliminate trapped bubbles. Don't be.
Air bubbles by completely dispersing the precipitate in the discharge liquid before filling the droplet discharge device into the tank or cartridge, and then dispersing the tank or cartridge with a weaker dispersion force than before filling the droplet discharge device We studied a dispersion method to prevent the uptake of water. However, in this method, when the tank or cartridge is mounted on the droplet discharge device, the dispersion force is changed to a weak dispersion force. However, due to the strong dispersion, many bubbles are taken into the ejection liquid. In order to eliminate the bubbles, the present invention disperses with a dispersion force lower than the dispersion force when dispersing the sedimentation section after the dispersion processing device completely disperses until the droplet discharge device is filled. The purpose is to let you.

In order to achieve the above object, the first means of the present invention is a dispersion method of discharge liquid used in an apparatus equipped with a tank or cartridge containing discharge liquid having micron-order particles. Before the use in the first step of completely dispersing the sedimentation portion with respect to the particle sedimentation portion in the tank or the cartridge, and after the sedimentation portion disappears until the discharge liquid is used in the apparatus. , And a second step of reducing the dispersion force and continuing the dispersion.
The second means of the present invention is characterized in that the dispersion processing is performed by changing the dispersion time depending on the storage period of the tank or the cartridge.
According to a third aspect of the present invention, there is provided a method for dispersing a discharge liquid, wherein the dispersion processing is performed by a device different from the dispersion processing device of the device.
A fourth means of the present invention is a method for dispersing a discharge liquid, wherein the dispersion treatment apparatus is an apparatus having a stirrer and a magnetic stirrer.
According to a fifth aspect of the present invention, there is provided a method for dispersing a discharge liquid, comprising the stirrer having a strong magnetic force and the magnetic stirrer.
A sixth means of the present invention is a method for dispersing a discharge liquid, wherein the operation of the magnetic stirrer is repeated rotation and stop.

In the first step of the present invention, the stirrer buried in the precipitated particles is forcibly moved and appears on the precipitation part by the dispersion using the strong magnetic stirrer and the magnetic stirrer. In the initial stage of rotation, it stays in one place, or the stirrer jumps and cannot perform normal stirring, but it is eliminated by intermittent operation. Precipitation and aggregation of particles in the discharge liquid are reliably dispersed and the discharge liquid concentration becomes uniform, thereby preventing clogging due to particle precipitation in the discharge liquid path in the droplet discharge device.
In addition, since the dispersion time of the discharged liquid that has settled depending on the state of the cartridge storage period can be shortened, dispersion can be performed efficiently.
Furthermore, in the second step, during the period from when the precipitate is completely dispersed to when it is mounted on the droplet discharge device, it is difficult to take in bubbles by reducing the dispersion force, and it is taken in when strongly dispersing. Air bubbles rise above the liquid surface to make it easier to eliminate. At the same time, it is possible to prevent sedimentation of dispersed particles.

As a dispersion treatment method, there are a method of shaking the discharge liquid put in a sealed container, a dispersion method using a stirrer, a dispersion method by ultrasonic irradiation, and a dispersion method using a stirrer and a magnetic stirrer, either One may be used, or two or more of these may be combined. Most preferred is a dispersion method using the stirrer and magnetic stirrer of the present invention.
In the dispersion method of the present invention, the dispersion is performed by the redispersion device before the cartridge is filled in the droplet discharge device. Dispersion is performed until there is no sedimentation of the discharge liquid (first step), and the dispersion is continued by reducing the dispersion force until the liquid droplet ejection device is filled with the discharge liquid after the sedimentation portion has disappeared (first step). Second step). The dispersion in the first step is changed according to the storage period of the cartridge. As shown in Example 1 to be described later, as the storage period becomes longer, dispersion time is required. Therefore, dispersion is performed by a dispersion device different from the droplet ejection device before filling the droplet ejection device. Accordingly, the dispersion time can be shortened, and the ink can be used efficiently.
Next, embodiments of the present invention will be described based on the drawings and examples.
FIG. 1 is a schematic view of a droplet discharge device 11 on which a cartridge 2 is mounted. A droplet discharge device 11 used in the present invention includes a head 2 for recording, a cartridge 2 having a tank 3 for storing a discharge liquid 5 having a particle diameter of 2 to 5 μm and a viscosity of about 10 to 15 mPa · s, and the discharge liquid. 5 has a redispersing device 1 for dispersing 5. The redispersion device 1 includes a magnetic stirrer having a magnetic force of about 0.6T. A cartridge 2 having a discharger 5 and a stirrer 4 whose magnetic material is samarium / cobalt is mounted in a tank 3, and the discharger 5 is dispersed by the rotation of the stirrer 4.
An example of a magnetic stirrer will be specifically described below. Made by ASONE; High-power stirrer REMIX, RP-1D, High-function high-power stirrer, ML-102, Ferromagnetic magnetic stirrer, HS-4SP, High-power stirrer, HS-100, manufactured by Nisshinka; Super-ferromagnetic stirrer SW -Use a magnetic stirrer such as RS077D.
Specific examples of the stirrer will be described below. Made by Isis; Teflon (registered trademark) HP rotor taper type CMH2930, Teflon (registered trademark) HP rotor taper type CMH2925, Teflon (registered trademark) HP rotor cylinder type CMH2930, Teflon (registered trademark) HP rotor cylinder type CMH2925 It is better to use a rotor such as
The redispersion device 1 in FIG. 2 is a dispersion processing device different from the magnetic stirrer 9 of the droplet discharge device 11. Preferably, before the cartridge 2 is mounted on the droplet discharge device 11, the discharge liquid 5 in the cartridge 2 is dispersed by the redispersion device 1 of FIG.
FIG. 3 is a flowchart for dispersing the discharge liquid.
The dispersion time varies depending on the storage state of the discharged liquid. In Kitahara's “Elucidation and Application Technology of Dispersion / Agglomeration” Technosystem (1996), the behavior represented by the following equation is known for the sedimentation time t of spherical dispersed particles in liquid (Equation 1) .

Here, η: viscosity, H: sedimentation distance, ρ: dispersed particle density, ρ0: dispersion medium density, D: dispersed particle diameter, and g: gravitational acceleration. In an actual system, there is a case that quantitatively deviates from the formula (1). However, as a general tendency, the settling time of the dispersed particles changes almost in proportion to the viscosity when other conditions are constant, The sedimentation rate tends to be almost inversely proportional to the viscosity.
The discharge liquid used in the present invention is η = 10 to 15 mPa · s, ρ = 1000 kg / m 3, ρ 0 = 1100 kg / m 3, and D = 2 to 5 μm.
Even if precipitation occurs during storage and the stirrer is buried in the particles, it can be dispersed by forcibly stirring at a rotational speed of 1000 rpm or more. In addition, when normal stirring cannot be performed due to jumping of the stirring bar, intermittent stirring is performed to return the stirring bar to the center when stopped, and normal stirring is performed at the center of the magnetic stirrer when stirring is started again. It is possible. The intermittent operation is preferably performed by, for example, stirring for 15 to 60 seconds, stopping for 5 to 15 seconds, or the like, and the intermittent time may be a combination in any range, and can be appropriately changed depending on the types of particles and the discharge liquid. The dispersion time varies depending on the ink type, viscosity, concentration, and storage state of the discharge liquid, but when the storage period is one month or less, a dispersion time of 15 to 40 minutes is required. When the storage period exceeds one month, a dispersion time of 40 to 120 minutes is required. In the second step, the dispersion time is until just before the cartridge 2 is filled, and the rotation speed is preferably about 300 rpm.
[Example 1]
The dispersion time depending on the storage period of the discharged liquid was confirmed.
Dispersion experiment of the discharge liquid having a viscosity of 13 mPa · s having a spacer fine particle with a particle diameter of 3 μm (manufactured by Toki Sangyo Co., Ltd., E-type viscometer, rotation speed 20 rpm, measurement temperature 23.0 ° C.) was conducted. A stirrer (manufactured by Isis Co., Ltd., Teflon (registered trademark) HP rotor taper type CMH2930) and 600 mL of discharge liquid are put into a 1 L container (container bottom diameter: 100 mm), and the storage period is 1 month, 2 months, 3 months, A sample of 4 months was stirred at 1400 rpm with a magnetic stirrer (Nisshin Rika Co., Ltd., super-strong magnetic stirrer SW-RS077D). Stirring was performed by intermittent operation of 60 seconds stirring and 5 seconds stop. Discharge liquid with a storage period of 1 month is 15 minutes, discharge liquid of 2 months is 15 to 30 minutes, discharge liquid of 3 months is 15 to 40 minutes, discharge liquid of 4 months is 30 to 40 minutes, and the storage period is long The tendency for the dispersion time to become longer was confirmed. The results are shown in FIG.
[Example 2]
Dispersion experiment of the discharge liquid having a viscosity of 13 mPa · s having a spacer fine particle with a particle diameter of 3 μm (manufactured by Toki Sangyo Co., Ltd., E-type viscometer, rotation speed 20 rpm, measurement temperature 23.0 ° C.) was conducted. In a 1 L container (container bottom diameter: 100 mm), a stirrer (manufactured by Isis Co., Ltd., Teflon (registered trademark) HP rotor taper type CMH2930) and 600 mL of the discharge liquid was put, and a magnetic stirrer (( The product was stirred at 1400 rpm using a Nisshin Rika Co., Ltd. super-strong magnetic stirrer SW-RS077D). Stirring was performed by intermittent operation of 60 seconds stirring and 5 seconds stop. The discharged liquid with a storage time of 1 month was completely free of sediment in 15 minutes.
After the precipitation part dispersion was completed, the rotational speed was reduced to 300 rpm while being mounted on the re-separation apparatus. The change in the amount of bubbles taken in was measured by reducing the number of rotations. The experimental results are shown in FIG. The amount of change in dissolved oxygen in the discharged liquid was measured using a personal dissolved oxygen meter TOX-90i manufactured by Toko Chemical Laboratory. After the dissolved oxygen amount obtained a constant value when the rotational speed was 1400 rpm, the rotational speed was lowered to 300 rpm. The amount of dissolved oxygen in the discharged liquid was reduced by nearly 10%, the intake of bubbles could be reduced, and the non-ejection occurrence rate was reduced from 50% when the rotational speed was not lowered to 30% when lowered.
Similarly, after the dispersion of the precipitation part was completed, the change in the concentration of the discharged liquid was measured after stirring at 300 rpm for 1 week. The experimental results are shown in FIG. The upper graph is a value obtained by measuring the concentration of the upper part of the discharge liquid in the tank, and the lower part is a value of the lower part of the discharge liquid in the tank. The concentration was measured using the laser scattering intensity of a particle size distribution meter LB-500 manufactured by Horiba, Ltd. There was no change in concentration in the initial state where stirring was performed at 1400 rpm and the state after 300 weeks at one week (336 hours), and the concentration was almost constant. It is possible to prevent sedimentation of particles even at a low speed of about 300 rpm.

The present invention relates to the production of electroluminescence, the production of printed wiring boards on which ink containing titanium oxide particles is printed, the production of multilayer ceramic electronic components and high-frequency electronics using high-concentration inks for electronic components that tend to settle and aggregate. The present invention can be applied in the field of dispersion technology such as manufacture of electronic parts such as parts and spacer particles of liquid crystal display devices.

It is the schematic of the droplet discharge apparatus which mounts the cartridge used by this invention after dispersion | distribution, and is filled with discharge liquid. FIG. 3 is a cross-sectional view of a cartridge and a redispersion device according to the present invention. It is a flowchart of the dispersion | distribution process of droplet discharge. It is a confirmation result of the dispersion time by the length of the storage period of the discharged liquid. This is a change in dissolved oxygen amount when the dispersion rotational speed is changed from 1400 rpm to 300 rpm. It is the result of having confirmed the density change of the discharge liquid and the presence or absence of a precipitation part in dispersion | distribution rotation speed 1400rpm and 300rpm.

Explanation of symbols

1: redispersion device, 2: cartridge, 3: tank, 4: stirrer, 5: discharge liquid, 6a to 6c: connection, 7: head, 8: droplet discharge circuit, 9: magnetic stirrer, 10 : Pump, 11: Droplet discharge device

Claims (6)

In a dispersion method of a discharge liquid used in an apparatus equipped with a tank or cartridge containing discharge liquid having micron-order particles, before the discharge liquid is used in the apparatus, it is applied to a particle sedimentation portion in the tank or the cartridge. On the other hand, it consists of a first step of completely dispersing the precipitation portion and a second step of continuing the dispersion by reducing the dispersion force until the discharge liquid is used in the apparatus after the precipitation portion disappears. A method of dispersing a discharge liquid characterized by the above. 2. The method for dispersing a discharge liquid according to claim 1, wherein the dispersion process is performed by changing a dispersion time depending on the storage period of the tank or the cartridge. 3. The method for dispersing a discharge liquid according to claim 1, wherein the dispersion processing is performed by an apparatus different from the dispersion processing apparatus of the apparatus. 4. The method for dispersing a discharge liquid according to claim 1, wherein the dispersion treatment device is a device having a stirrer and a magnetic stirrer. 5. A method for dispersing a discharge liquid according to claim 4, comprising the stirrer having a strong magnetic force and the magnetic stirrer. 6. The method of dispersing a discharge liquid according to claim 4, wherein the operation of the magnetic stirrer is repeated rotation and stop.

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