JPH11235826A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head having a low cost ink-repellent film which is superior in abrasion resistance and has a sufficient ink repellence stable for a long time. SOLUTION: A block polymer consisting of a pair of polymer including fluoroalkyl radical and polymer including non-cyclic hydrocarbon and a polymeric material are mixed to be dissolved in a solution or the block polymer is dispersed into the polymeric material, then it is coated on a nozzle face to be dried and subjected to a heating treatment so that an ink-repellent film is formed. When a content rate of the block polymer is in a range of 0.5-7 weight %, it is possible to obtain the ink-repellent film having a superior ink repellence of which contact angle to ink with a low surface tension is not less than 85 deg. and a superior abrasion resistance wherein the number of times of wiping for starting peeling is not less than 10,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink repellent film formed on a nozzle surface of an ink jet recording head used in an ink jet recording apparatus.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing an example of the structure of an ink jet recording head (hereinafter simply referred to as a recording head), and FIG. 3 is a partially enlarged view of FIG. The recording head is a flow path substrate 1 in which a groove for forming the ink conduit 3 is formed.
And a vibrating plate 2 joined to the groove-side surface to form an ink conduit 3. The ink supplied from the ink supply source 9 to the ink conduit 3 of such a recording head is rapidly pressurized in the ink pressurizing chamber 32, and
The ink is ejected from the nozzle opening 35 as an ink droplet, adheres to the recording medium, and performs recording. In the case of FIG.
Pressurizes the ink.

[0003] A glass plate or a metal plate as the diaphragm 2 is provided in a nozzle opening 35 of an ink nozzle 34 from which ink is discharged.
A silicon substrate, a metal substrate, a resin substrate, or the like is used as the flow path substrate 1. Ink adheres and spreads easily on the surface of these materials, and if ink adheres to the vicinity of the nozzle opening 35, the straightness of the ejected ink deteriorates, which causes deflection of the ink droplet flight and disturbs printing. As a result, the image quality is remarkably reduced, and in some cases, an ink non-discharge nozzle is generated. Therefore, it cannot be put to practical use as it is.

Further, when a recording head is used, it is necessary to wipe off dirt and ink on the surface of the nozzle surface 5 without fail.
The nozzle surface 5 is rubbed by a wiper provided in the ink jet recording apparatus in response to a periodic maintenance command or a print defect removal command based on print state monitoring data. Therefore, the ink repellent film 6 is also required to withstand the mechanical friction caused by the wiper. This rubbing resistance is required to withstand 10,000 (10K) to 40,000 (40K) wiping operations. The number of times varies depending on the adhesion state of the ink, and is small in the case of a surface that is not easily attached, and is large in the case of a surface that is easily attached.

In order to prevent the ink from adhering to the nozzle opening 35 and diffusing on the nozzle surface 5, an ink-repellent film as an ink-repellent treatment is provided around the nozzle opening 35 or on the entire nozzle surface 5. 6 are formed. 2 and 3, the ink-repellent film 6 is formed directly on the nozzle surface 5, but the ink-repellent film is formed on a separately prepared nozzle plate, and the nozzle plate is attached to the nozzle surface 5. Some recording heads are joined.

Various methods have been proposed for such ink repellent treatment. In general, even if a material having ink repellency, for example, a fluoride polymer, is directly applied to the nozzle surface 5, the adhesion strength is very weak, so that the ink repellent material is directly applied to the nozzle surface 5 or the nozzle surface. It is not formed on a plate (hereinafter, represented by the nozzle surface 5). A method for dispersing an ink-repellent material such as a fluoride polymer in a material having good adhesion to the nozzle surface 5 to secure the adhesion is disclosed in Japanese Patent Application Laid-Open No. 57-157765. A method using electrostatic coating, a method using eutectoid plating of a fluoride polymer and nickel disclosed in JP-A-60-183161, a method using a fluorine resin disclosed in JP-A-60-255441, There is a method using a resin in which fluorine resin particles are dispersed. In these methods, when the component is increased in order to improve the ink repellency, the rub resistance is lowered and becomes insufficient, and it is difficult to achieve both properties. Further, in the case of eutectoid plating, since a fluoride polymer is dispersed in nickel, there is a problem that nickel is corroded by components in the ink, particularly, alkaline components.

As another means for ensuring the adhesion between the ink-repellent film 6 and the nozzle surface 5, there are the following means. In the method disclosed in Japanese Patent Application Laid-Open No. 4-158046, a fluorine-based surfactant is mixed with a silicone resin in a predetermined ratio, applied and heat-treated to quickly transfer the fluorine-based surfactant to the resin surface. The resin-affinity portion is compatible with the resin side, and the ink-repellent portion is oriented toward the air, so that both ink repellency and abrasion resistance are to be achieved. Further, disclosed in JP-A-4-279358, an oxide film is formed on a nozzle plate, and an anchor coat layer having a coupling agent containing Si is provided on the oxide film,
Further, a thin film of a polymer containing a fluorine-containing heterocyclic structure in the main chain is formed thereon. According to the method disclosed in JP-A-6-328688, a thin zirconia layer is formed on the surface of the nozzle plate. A film is formed, and a layer made of a fluorine-containing silicon coupling agent is provided thereon.

On the other hand, in recent years, in the ink jet recording system, high resolution and high contrast for image quality have been required.
There are strong demands for colorization and high speed, etc., and improvements to inks that have high permeability to ink receiving media,
Improvements in dispersion stability have been implemented. As these improvement measures, alcohols, ethers, surfactants and the like are mainly added to the ink composition. However, these additives generally have low surface tension and reduce the surface tension of the ink. When the surface tension of the ink decreases, the contact angle of the ink on the nozzle surface 5 decreases, and the adhesion and diffusion of the ink to the nozzle surface 5 as described above more easily occur.

In such a situation, when the ink repellent film 6 according to the prior art as described above is examined again, it is found that the one disclosed in Japanese Patent Application Laid-Open No. 4-158046 is as follows.
The contact angle of the ink is 78 degrees at the maximum, and the ink repellency is not sufficient, and JP-A-4-279358 and JP-A-6-279358
In the method disclosed in Japanese Patent No. 328688, the number of manufacturing steps is large, and it is difficult to ensure sufficient abrasion resistance. in this way,
The conventional ink repellent film cannot provide sufficient ink repellency and abrasion resistance.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a low-cost, excellent abrasion resistance, stable and sufficient ink repellency for a long period of time. An object of the present invention is to provide a recording head having an ink-repellent film.

[0011]

According to the present invention, there is provided an ink jet printer having an ink conduit having an ink pressurizing chamber, an ink nozzle and the like, and having an ink repellent film on a nozzle surface which is an opening of the ink nozzle. In the recording head,
An ink-repellent film formed by mixing and dissolving a polymer and a block polymer comprising a pair of a fluoroalkyl group-containing polymer and an acyclic hydrocarbon polymer in a solvent, or the block polymer Is a film formed by dispersing in a polymer material (the invention of claim 1).

Since the ink-repellent film is formed of a pair of a block polymer composed of a pair of a fluoroalkyl group-containing polymer and an acyclic hydrocarbon polymer and a polymer material, sufficient bonding strength with the nozzle surface is obtained. The acyclic hydrocarbon polymer of the block polymer is firmly held as an anchor in the polymer material capable of ensuring the above, and the polymer having an alkyl fluoride group exposed on the surface exhibits sufficient ink repellency.

In the first aspect of the present invention, the acyclic hydrocarbon polymer is an acrylic polymer, and the polymer material is an ultraviolet-curable resin or a thermosetting resin (the second aspect of the invention). Acrylic polymer and UV curable resin or thermosetting resin have very good adhesion, and when polymer material is cured, acrylic polymer is more firmly held by polymer material, and anchor effect is exhibited more strongly Is done.

In the first aspect of the invention, the block polymer is contained in the polymer material in an amount of 0.5 to 7% by weight (the third aspect of the invention). 0.5 to 7% by weight of block polymer
According to the examination results, the range corresponds to a range in which a sufficient contact angle and a sufficient abrasion resistance can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a recording head according to the present invention will be described with reference to examples. Since the configuration of the recording head is the same as that of the prior art, FIGS.
The configuration will be described. Using a silicon wafer for the flow path substrate 1 and a glass plate for the vibration plate 2, a recording head having the structure shown in FIG. The diameter of the nozzle opening 35 of this recording head is several tens μm. The ink repellent film 6 is formed on the nozzle surface 5 of the recording head by the following method.
Was formed.

A cardo epoxy resin having excellent adhesion to silicon and glass is selected as a polymer material for securing the adhesive strength to the nozzle surface 5, and this resin is dissolved in diethylene glycol dimethyl ether at 10% by weight to form a resin solution. A block polymer comprising a fluororesin segment and an acrylic resin segment, which is a block polymer comprising a pair of a fluoroalkyl group-containing polymer and an acyclic hydrocarbon polymer, is prepared by mixing 1/1 of methyl ethyl ketone and methyl isobutyl ketone. Disperse 30% by weight in a mixture of
The resin solution and the dispersion are mixed and sufficiently stirred to prepare a dispersion in which the ratio of the solid content of the block polymer to the solid content of the cardo epoxy resin is changed within a range of 0 to 8% by weight. did.

Using a foamed polyurethane foam sheet having a thickness of about 20 mm, this dispersion is filled in the foam sheet so that the surface of the foam sheet and the dispersion liquid surface are the same, and air is blown out from the ink nozzles 34 of the recording head. Then, the foam sheet was gently brought into contact with the nozzle surface 5 to apply the dispersion liquid to the nozzle surface 5 (kiss coating method), and the solvent was dried for 3.5 minutes. Thereafter, the resin was heated at 200 ° C. for 1 hour to cure the resin, thereby forming an ink-repellent film 6 having a thickness of about 0.5 μm.

The cardo of the cardo epoxy resin is an anchor, and a resin in which the ends of the resin chain are curved in a hook shape is called a cardo epoxy resin. This resin is employed to hold the acrylic resin segment of the block polymer as strongly as possible. Of course, in the present invention, ordinary epoxy resin can be used. Also,
A block polymer comprising a pair of a fluorinated alkyl group-containing polymer and an acyclic hydrocarbon polymer is defined as AA when the fluorinated alkyl group is A and B is the acyclic hydrocarbon. A]-[B ... BB] is a block polymer having a structure represented by the following formula. In the examples used, [AA ... A] is a fluororesin segment, and [B ... BB] Is an acrylic resin segment.

The ink-repellent film 6 thus formed
In order to evaluate the ink repellency of the ink, the contact angle of the ink having a low surface tension of 35 mN / m was measured, and the recording head having the ink repellent film 6 was mounted on a recording apparatus. The printing characteristics and the abrasion resistance were evaluated. The wiping conditions for the abrasion resistance test were a weight of 80 g, a wiping speed of 100 mm / sec, a wiping material of 1 mm in thickness, and a silicone rubber having a hardness of 40 degrees.

FIG. 1 is a graph showing the contact angle of low surface tension ink and the results of abrasion resistance test with respect to the content of the block polymer in the ink repellent film 6 thus formed. The contact angle of the ink rapidly increases initially with an increase in the content of the block polymer, exceeds the required contact angle of 85 ° at a content of 0.5% by weight, and saturates at a little less than 110 °. On the other hand, the number of wipings at the start of peeling as the abrasion resistance test has a tendency opposite to the contact angle, and gradually decreases from the initial number of wipings of nearly 70,000 with an increase in the content of the block polymer. Exceeds 5% by weight, the value exceeds 40,000 times, which is the first target value of the abrasion resistance, and decreases to 10,000 times, the second target at 7% by weight.

The first target value of 40,000 times is equivalent to performing wiping nearly once for 50,000 prints. In a region where the contact angle exceeds 85 degrees, the ink is discharged from the nozzle surface. 5, which is equivalent to having sufficient abrasion resistance for printing 50,000 sheets. If the content exceeds 7% by weight, the formation of the ink repellent film 6 itself becomes difficult.

According to the above results, in the recording head on which the ink repellent film 6 having the contact angle of 85 degrees or more was formed, the ink did not adhere to the nozzle openings 35, the ejected ink droplets did not deflect, and the printing disorder occurred. There was no remarkable deterioration of the image quality and no occurrence of non-discharge nozzles. The contact angle of the ink-repellent film 6 with the above ink having a contact angle of 85 degrees with ion exchanged water was 110 degrees.

Therefore, it can be said that the desirable content of the block polymer is 0.5 to 7% by weight. Note that the wiping does not reduce the contact angle of the coating 6, and the peeling of the coating 6 reduces the contact angle. In the above embodiment, a thermosetting cardo epoxy resin is used as the resin, but it can be replaced with an ultraviolet curing resin. Similar results can be obtained by replacing diethylene glycol dimethyl ether with cyclohexanone, dioxane, methyl ethyl ketone or the like as a solvent for dissolving the resin,
The solvent in which the block polymer is dispersed is not limited to a 1/1 mixture of methyl ethyl ketone and methyl isobutyl ketone. Further, similar results were obtained even when the dispersion amount of the block polymer dispersion was changed to 3% by weight.

[0024]

According to the present invention, there is provided an ink jet recording head having an ink conduit comprising an ink pressurizing chamber, an ink nozzle, and the like, and having an ink repellent film on a nozzle surface which is an opening of the ink nozzle. , Ink repellent film,
A film formed by mixing and dissolving a block polymer consisting of a pair of a fluoroalkyl group-containing polymer and an acyclic hydrocarbon polymer and a polymer material in a solvent, or dispersing the block polymer in a polymer material Because it is a film formed by making it, a polymer material that can secure sufficient bonding strength with the nozzle surface,
The acyclic hydrocarbon polymer of the block polymer is firmly held as an anchor, and the alkyl fluoride group-containing polymer on the surface exhibits sufficient ink repellency. Therefore, it is possible to provide a recording head having an ink-repellent film which is inexpensive, has excellent rubbing resistance, and has stable and sufficient ink-repellent performance over a long period of time (the invention of claim 1).

In the first aspect of the present invention, the acyclic hydrocarbon polymer is an acrylic polymer, and the polymer material is an ultraviolet curable resin or a thermosetting resin. Acrylic polymer and UV curable resin or thermosetting resin have very good adhesion, and when polymer material is cured, acrylic polymer is more firmly held by polymer material, and anchor effect is exhibited more strongly Is done. Therefore, an acrylic polymer as an acyclic hydrocarbon polymer and an ultraviolet-curable resin or a thermosetting resin as a polymer material are an optimal combination of materials, and are inexpensive and have low abrasion resistance. It is possible to provide a recording head provided with an ink-repellent film having excellent, long-term stability and sufficient ink-repellent performance (the invention of claim 2).

In the first aspect, the block polymer is contained in the polymer material in an amount of 0.5 to 7% by weight. According to the examination results, the range of the block polymer in the range of 0.5 to 7% by weight corresponds to a range in which a sufficient contact angle and a sufficient rubbing resistance can be obtained. Therefore, an ideal ink-repellent film can be formed by incorporating 0.5 to 7% by weight of a block polymer in a polymer material.
Invention).

[Brief description of the drawings]

FIG. 1 is a diagram showing characteristics of an ink-repellent film of an embodiment of an ink jet recording head according to the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of an example of an inkjet recording head.

FIG. 3 is a partially enlarged view of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path board 2 Vibration plate 3 Ink conduit 31 Ink supply path 32 Ink pressurization chamber 33 Ink ejection path 34 Ink nozzle 35 Nozzle opening 4 Piezoelectric element 5 Nozzle surface 6 Ink repellent film 9 Ink supply source

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuyuki Osawa Fuji Electric Co., Ltd. 1-1 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa

Claims (3)

[Claims] 1. An ink jet recording head having an ink conduit formed of an ink pressurizing chamber, an ink nozzle, and the like, and having an ink repellent film on a nozzle surface which is an opening of the ink nozzle. A film formed by mixing and dissolving a block polymer comprising a pair of a fluoroalkyl group-containing polymer and an acyclic hydrocarbon polymer and a polymer material in a solvent, or forming the block polymer into a polymer material An ink jet recording head, which is a film formed by dispersion. 2. The ink jet recording head according to claim 1, wherein the acyclic hydrocarbon polymer is an acrylic polymer, and the polymer material is an ultraviolet curable resin or a thermosetting resin. 3. The polymer according to claim 1, wherein the block polymer is 0.5 to 7%.
2. The ink jet recording head according to claim 1, wherein said ink jet recording head is contained by weight%.