JPH06328698A - Ink jet recording head and apparatus - Google Patents

Abstract

PURPOSE:To enable the boring processing of the ink emitting part of an ink jet recording head regardless of the thickness of a water repelling film and to increase the selection width of the coating thickness of a water repelling agent by adding an ultraviolet absorber to the water repelling agent to enhance the ultraviolet absorptivity of the water repelling agent. CONSTITUTION:In an ink jet recording head wherein a water repelling film composed of a water repelling agent being a fluorine-containing copolymer having a ring structure in its main chain is formed on a base material in the periphery of each emitting part, the water repelling agent contains an ultraviolet absorber or a compd. having the ultraviolet absorber chemically bonded thereto and the ultraviolet absorptivity shown at least in one wavelength out of the wavelengths of 193, 248 and 308nm of the water repelling film is made larger than that of a water repelling film composed only of the water repelling agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head for ejecting and flying a recording liquid, which is generally called ink, from a fine opening (orifice) as a small droplet.

[0002]

2. Description of the Related Art In an ink jet recording head,
It is known that stable ejection cannot be performed when the recording liquid is accumulated in the peripheral portion of the ejection port. In order to solve this problem, many proposals have hitherto been made to form a water-repellent treatment layer that repels ink by applying a water-repellent treatment to at least the peripheral portion of the ejection port.

In the case of carrying out the ink jet recording head method, the head is always in contact with the recording liquid even if the periphery of the discharge port is subjected to the water repellent treatment, so that an absorbent body such as polyurethane foam is used. Therefore, it is necessary to wipe the surface of the orifice and suck the ink that has adhered, or scrape it with a rubber blade. Therefore, the ink jet recording head is required to have durability against wiping, and for example, as disclosed in Japanese Patent Application No. 2-193686, a fluorine-containing copolymer having a cyclic structure (CYTOP; Asahi Glass Co., Ltd.) is water repellent. Used as an agent.

FIG. 1 shows an ink jet recording head which has been subjected to a water repellent treatment. In FIG. 1a, the water-repellent film 1 is formed on the grooved top plate 3 produced by integrally molding the liquid chamber, the flow path, and the discharge port surface by applying Cytop which is a water-repellent agent and subsequent thermosetting. There is. FIG. 1b is a top plate with a groove in which the ejection port 4 is formed by irradiating an excimer laser from the back side (flow path side) of the ejection port formation surface of FIG. 1a and the recording liquid is ejected from the ejection port. FIG. 6 is a diagram of a head manufactured by adhering a substrate 5 having a heating element, which is a means for performing the heating. Here, as a material of the grooved top plate 3, polysulfone or the like is used in consideration of moldability and ink resistance.

[0005]

However, CYTOP hardly absorbs light in the ultraviolet region having wavelengths of 193 nm, 248 nm and 308 nm and transmits 95% or more of the light. Therefore, the discharge port is formed by processing with an excimer laser. Not suitable for. Therefore, the actual drilling is performed by blowing off the CYTOP with the force when the polysulfone scatters. Therefore, when the layer thickness of CYTOP is large, there is a problem that hole processing cannot be performed, a problem that peeling occurs at the interface between CYTOP and the base material,
It is necessary to control the thickness of CYTOP to 2 μm or less.

[0006]

The present invention is an ink jet recording in which a water repellent film made of a water repellent which is a fluorine-containing copolymer having a cyclic structure in its main chain is formed on a substrate around a discharge portion. In the head, the water repellent contains (1) an ultraviolet absorber and / or (2) a compound in which the ultraviolet absorber is chemically bonded to the water repellent, and the water repellent film has a wavelength of 193 nm, 24.
Provided are an inkjet recording head and an inkjet recording apparatus equipped with the inkjet recording head, wherein the ultraviolet absorption rate of at least one of 8 nm and 308 nm is higher than the absorption rate of a water-repellent film composed only of the water-repellent agent. To do.

The present invention is particularly effective in an ink jet recording type recording head and a recording apparatus which form flying droplets by utilizing thermal energy among the ink jet recording methods.

Regarding the typical structure and principle thereof, for example, US Pat. Nos. 4,723,129 and 4740.
No. 796, the present invention is preferably carried out using these basic principles. This recording method is applicable to both the so-called on-demand type and the continuous type.

To briefly explain this recording method, an electrothermal converter is arranged corresponding to a sheet or liquid path holding a liquid (ink), and a liquid (ink) corresponding to recording information. Heat energy is generated by applying at least one drive signal for giving a rapid temperature rise that causes the film boiling phenomenon beyond the nucleate boiling phenomenon, and causes the film boiling on the heat acting surface of the recording head. . In this way, bubbles can be formed in one-to-one correspondence with the drive signal applied from the liquid (ink) to the electrothermal converter, which is particularly effective for the on-demand recording method. The liquid (ink) is ejected through the ejection holes by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make the driving signal into a pulse shape because bubbles can be grown and contracted immediately and appropriately, and thus a liquid (ink) with excellent responsiveness can be ejected. This pulse-shaped drive signal is described in US Pat. No. 4,463,359 and US Pat.
Those as described in 45262 are suitable. If the conditions described in US Pat. No. 4,313,124, which is an invention relating to the rate of temperature rise on the heat acting surface, are adopted, more excellent recording can be performed.

The structure of the recording head is a combination of a discharge hole, a liquid flow path, and an electrothermal converter as disclosed in the above-mentioned specifications (straight liquid flow path or right-angled liquid flow path). In addition, as disclosed in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, the present invention includes those having a configuration in which a heat acting portion is arranged in a bending region.

In addition, Japanese Laid-Open Patent Publication No. 123670/1984, which discloses a structure in which a common slit is used as a discharge hole of the electrothermal converter for a plurality of electrothermal converters, and a pressure wave of thermal energy is absorbed. The present invention is also effective in a structure based on Japanese Patent Laid-Open No. 138461/1984, which discloses a structure in which the corresponding opening corresponds to the discharge portion.

Further, as a recording head in which the present invention is effectively used, there is a full line type recording head having a length corresponding to the maximum width of the recording medium which can be recorded by the recording apparatus. The full line head may be a full line configuration formed by combining a plurality of print heads as disclosed in the above specification, or may be a single full line print head integrally formed.

In addition, by being mounted on the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. The present invention is also effective when a cartridge-type recording head that is specially provided is used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc. to the recording apparatus of the present invention because the recording apparatus of the present invention can be made more stable. If you list these specifically,
A capping unit, a cleaning unit, a pressure or suction unit, an electrothermal converter or a heating element other than this, or a preheating unit using a combination of these, and a preliminary ejection mode different from recording are provided for the recording head. Adding a means for performing is also effective for stable recording.

Further, the recording mode of the recording apparatus is not limited to the mode in which only the mainstream color such as black is recorded, and either the recording head may be integrally formed or a combination of plural recording heads may be used. However, the present invention is also extremely effective for an apparatus provided with at least one of a multicolor of different colors or a full color by color mixing.

Although the liquid ink has been described above, an ink that is solid at room temperature or an ink that is in a softened state at room temperature can be used in the present invention.
In the above-mentioned ink jet device, it is common to control the temperature of the ink itself within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. Any liquid may be used as long as the ink is liquid.

In addition, the excessive temperature rise of the head or ink due to thermal energy is positively prevented by using it as the energy for the state change of the ink from the solid state to the liquid state, or the evaporation of the ink is prevented. It is also possible to use an ink that solidifies when left as it is. In any case, liquefaction occurs only when heat energy is applied, such as when ink is liquefied by applying heat energy according to a recording signal and ejected as an ink liquid, or when it reaches the recording medium, it already begins to solidify. The use of an ink having such a property is also applicable to the present invention.

Such an ink is disclosed in JP-A-54-568.
No. 47 or JP-A No. 60-71260, facing the electrothermal converter in the state of being held as a liquid or solid in the recesses or through holes of the porous sheet. It may be in the form.

In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

FIG. 4 is an external perspective view showing an example of an inkjet recording apparatus (IJRA) in which the recording head obtained by the present invention is mounted as an inkjet head cartridge (IJC).

In FIG. 4, reference numeral 20 denotes an ink jet head cartridge (IJC) having a group of nozzles for ejecting ink so as to face the recording surface of the recording paper fed onto the platen 24. Reference numeral 16 is a carriage HC that holds the IJC 20, and is connected to a part of a drive belt 18 that transmits the driving force of the drive motor 17, and is slidable with two guide shafts 19A and 19B arranged in parallel with each other. By doing so, reciprocating movement over the entire width of the recording paper of the IJC 20 is possible.

Reference numeral 26 is a head recovery device, which is an IJC 20.
Is arranged at one end of the movement path of, for example, at a position facing the home position. The drive force of the motor 22 via the transmission mechanism 23 causes the head recovery device 26 to operate, and
Cap the JC20. In association with the capping of the IJC 20 by the cap portion 26A of the head recovery device 26, ink is sucked by an appropriate suction means provided in the head recovery device 26 or by an appropriate pressure means provided in an ink supply path to the IJC 20. The ejection recovery process is performed such that the ink is pressure-fed and the ink is forcibly discharged from the ejection port to remove the thickened ink in the nozzle. Further, the IJC is protected by capping at the end of recording.

Reference numeral 30 is a blade as a wiping member which is disposed on the side surface of the head recovery device 26 and is made of silicon rubber. The blade 30 is a blade holding member 30.
The head recovery device 26 is held by A in a cantilever form.
Similarly to the above, the motor 22 and the transmission mechanism 23 operate to enable engagement with the ejection surface of the IJC 20. As a result, the blade 30 is projected into the movement path of the IJC 20 at an appropriate timing in the recording operation of the IJC 20 or after the ejection recovery process using the head recovery device 26, and the ejection surface of the IJC 20 is moved along with the movement operation of the IJC 20. Wipe off condensation, wetness or dust.

[0024]

[Function] A wavelength of 193 nm, 248 nm and /
Alternatively, an ultraviolet absorber is used to have absorption in the ultraviolet region of 308 nm. At that time, the selection and the compounding ratio of the ultraviolet absorber to be used are determined by the kind of the water repellent. As a method of adding the ultraviolet absorber, the ultraviolet absorber may be dispersed in the water repellent (dispersion type) or may be chemically bonded (bond type) to the terminal of the water repellent molecule.

Further, which of the above three regions is used as the ultraviolet region for enhancing absorption is determined in consideration of the excimer laser gas to be used and the type of material to be processed.

[0026]

【Example】

(Example 1) Using KrF gas as a laser gas,
The processed product was polysalifone, and in consideration of the properties of the processed product, an ultraviolet absorber for increasing absorption at 248 nm was added. That is, the following two types of water repellents were produced by changing the ultraviolet absorber and the addition method thereof. (1) Compound 1 having the following structure dispersed in CYTOP (containing 10% of compound 1 based on solid content)

[0027]

[Chemical 1] (2) A Cytop derivative of Compound 2 and Compound 3 having the following structures by chemically bonding an ultraviolet absorber to the terminal of Cytop molecule by a condensation reaction.

[0028]

[Chemical 2]

[0029]

[Chemical 3] The UV transmittances of the two water repellents thus obtained were measured and are shown in the graph of FIG. 2 together with the results of the transmittances obtained for CYTOP containing no UV absorber.
From this figure, when the ultraviolet absorbent is chemically bonded to Cytop, the transmittance at 248 nm is reduced by about 5 to 10% as compared with the case of Cytop alone, and the absorption rate is improved. I understand.

Next, according to the following procedure, (A) a base material coated with a water repellent consisting only of CYTOP and (B) a base coated with a water repellent obtained by dispersing Compound 1 in CYTOP. The material and the (C) CYTOP were chemically reacted to evaluate the laser processability of the base material coated with the water repellents obtained as the compound 2 and the compound 3 which are CYTOP derivatives.

1) First, a water repellent having a thickness of 2 μm was applied to a polysulfone film having a thickness of 40 μm.

2) Thereafter, with respect to (A) and (C), heat curing was carried out under the condition of 150 ° C. for 1 hour, and (B).
Since it has a sublimation property, it was left at room temperature for 1 day.

3) Next, an excimer laser was irradiated from the polysulfone side to observe the state of drilling.

The results are shown schematically in FIG. As shown in this figure, the hole (A) could not be drilled, and the holes (B) and (C) could be drilled. However,
Comparing the processed states of (B) and (C), as shown in FIG. 3, the edge of the water-repellent film part is sharper and the state of the processed surface is better in (C), but in the case of (B) Peeling was observed at the interface between the substrate and the water repellent.

In this Example, a mixture of compound 2 and compound 3 was used as the bond-type water repellent, but other than that, for example, compound 2 alone, compound 3 alone, and a part of Cytop were obtained. It goes without saying that the same effect can be obtained in the case of a mixture of Cytop, compound 2 and compound 3 as well.

[0036]

As described above, by adding an ultraviolet absorber to the water repellent to improve the ultraviolet absorption rate,
Holes can be formed in the ink ejection portion of the inkjet recording head regardless of the thickness of the water repellent film. This broadens the selection range of the thickness of the water-repellent agent coating, and improves yield and operation rate. Furthermore, since the thickness of the water-repellent film can be increased, it is possible to improve the strength of the discharge port forming surface regardless of the material of the base material, and an inkjet that is effective against blade rubbing, paper jam, etc. A recording head can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of an inkjet recording head,
(A) is a grooved top plate obtained by integrally molding a liquid chamber, a flow path, and a discharge port surface, and (b) is a discharge port (a)
FIG. 6 is a diagram of a head manufactured by adhering the grooved top plate of FIG.

FIG. 2 is a graph of ultraviolet absorption curves of various water repellent films.

FIG. 3 is a diagram schematically showing the laser processability of a base material coated with various water repellents. A shows a case where only the water repellent is CYTOP, and B shows a case where the water repellent is added to CYTOP. In the case of the dispersion type in which 1 is dispersed, C is a diagram in the case where the water repellent is a combined type in which Cytop is combined with the ultraviolet absorber.

FIG. 4 is a perspective view showing an example of a recording apparatus equipped with the inkjet recording head of the present invention.

[Explanation of symbols]

 1 Water-repellent film 2 Ink supply port 3 Groove top plate 4 Discharge port 5 Substrate 6 Base material 7 Water-repellent film 16 Carriage 17 Drive motor 18 Drive belt 19A, 19B Guide shaft 20 Inkjet head cartridge 22 Cleaning motor 23 Transmission mechanism 24 Platen 26 Cap member 30 Blade 30A Blade holding member

Claims (7)

[Claims] 1. In an ink jet recording head in which a water repellent film made of a water repellent which is a fluorine-containing copolymer having a cyclic structure in its main chain is formed on a base material around a discharge portion, the water repellent is ( 1) a UV absorber and / or (2) a UV absorptivity which the water repellent film contains at least one wavelength of 193 nm, 248 nm and 308 nm, containing a compound in which a UV absorber is chemically bonded to the water repellent. Is higher than the absorption rate of a water-repellent film composed only of the water-repellent agent. 2. The ink jet recording head according to claim 1, wherein the water repellent film has a UV absorptivity of 10% or more at a wavelength of 248 nm. 3. The ink jet recording head according to claim 1, wherein the base material around the ejection portion is made of any one of polymer resin, glass, silicon and metal. 4. The ink jet recording head according to claim 1, wherein the discharge port is a discharge unit processed by an excimer laser. 5. The electro-thermal conversion element for causing the ink ejection energy generating element to generate heat by applying electric energy to cause the ink to change state and eject the ink. The inkjet recording head according to 1. 6. The inkjet recording head according to claim 1, wherein the inkjet recording head is a full-line type in which a plurality of ejection openings are provided over the entire width of the recording area of the recording medium. . 7. The ink ejection port for ejecting ink is provided facing a recording surface of a recording medium.
An ink jet recording apparatus comprising at least the recording head according to any one of 1 to 4 and a member for mounting the recording head.