JP2887816B2 - Inkjet recording head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording head of an ink jet recording apparatus, and more particularly to an ink jet recording head which has been subjected to a liquid repellent treatment.

(Prior Art) In the ink jet recording method, ink on a recording medium is caused to fly as droplets, and the ink is adhered to a recording member such as paper to perform recording.

The physical properties of the surface of the ink ejection port of the recording head used in the ink jet recording method greatly affect the stable ejection of the recording ink.

That is, if ink accumulation due to the outflow of recording ink or the like occurs around the ink ejection port, the surface state of the ink ejection port surface becomes uneven, and when the ink is ejected from the ink ejection port, the ejection direction and ejection This causes a reduction in recording quality, such as a change in speed or a variation in the particle size of ink droplets.

Furthermore, if the entire surface of the periphery of the ink discharge port is covered with the recording ink, it may become impossible to discharge the ink droplet.

Therefore, as a method for solving these problems, many proposals have been made to perform a liquid repellent treatment on the ink ejection port surface.

A conventionally attempted liquid repellent treatment method is to form a liquid repellent film on an ink ejection surface. As the liquid-repellent coating, as described in JP-A-60-255441,
One using a fluororesin or a resin in which fluororesin particles are dispersed, one using a plasma polymerized film of a fluorine compound gas, as described in JP-A-60-178065,
Alternatively, as described in JP-A-59-194864, there is a method using a silicone resin.

However, these coatings are not necessarily sufficient in terms of properties such as liquid repellency, adhesion to a substrate, and abrasion resistance of the coating. When the composition ratio is small, the lyophobic effect is low, and when the composition ratio of fluorine is increased, problems such as poor adhesion and reduced wear resistance are caused.

Also, as described in JP-A-60-202743, it has been proposed to provide an intermediate layer in order to obtain adhesion between the liquid-repellent coating and the substrate, but the process becomes complicated. There is a problem that productivity is reduced.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-described problems, and has been achieved by using a liquid-repellent coating of a new material different from the conventional liquid-repellent coating. It is an object of the present invention to provide an ink jet recording head which has solved the above problems.

(Means for Solving the Problems) According to the present invention, in an ink jet recording head having an ink ejection port for ejecting ink, an end face having the ink ejection port is made of a resin having a large adhesive force to a material of the ink ejection port. In addition, a film made of a resin in which a fluorine-based surfactant is added is formed.

(Operation) The ink jet recording head of the present invention employs a resin in which a fluorine-based surfactant is internally added to a resin having a large adhesive strength to an ink ejection port material and a sufficient strength on an ink ejection surface thereof. A coating is formed by applying and curing. Since the resin has a large adhesive force with the ink ejection port material, this coating film has good adhesiveness, and a liquid repellent effect is provided by internally adding a fluorine-based surfactant.

(Embodiment) FIG. 1 is a schematic sectional view of an embodiment of the ink jet recording head of the present invention. In the figure, 1 is a heater substrate,
2 is a channel substrate, 3 is a heater, 4 is an ink supply port, 5 is an ink chamber, 6 is an ink discharge port, and 7 is a liquid repellent coating. In addition, illustration of an electrode, a protective film, etc. for supplying electricity to the heater is omitted. In this embodiment, the ink ejection ports 6 communicating with the ink chambers 5 are thermal ink jet recording heads in which 128 are arranged at a pitch (63.5 μm) corresponding to a resolution of 400 DPI.

The material of the heater substrate 1 and the channel substrate 2 constituting the thermal ink jet recording head is Si, and therefore, the surface around the ink discharge ports 6 is Si. A liquid-repellent coating 7 is formed on the surface around the ink ejection port 6.
Are formed.

The step of forming the liquid-repellent coating on the surface around the ink ejection port 6 will be described.

First, a 17% isopropyl alcohol solution of a silicon resin having good adhesion to Si (for example, X12-2206 manufactured by Shin-Etsu Chemical Co., Ltd.) is added to a fluorine-based surfactant (for example, Megafac F-manufactured by Dainippon Ink and Chemicals, Inc.). 177) 1%
It was added and the treatment liquid was adjusted.

The recording head, the N ₂ gas from the ink supply port 4, the flow rate 1 [1 / min] is ejected toward the discharge port 6 in extent, the ink discharge port surface in the processing solution described above in that state 20
Soaked for seconds. The recording head was pulled up from the treatment liquid, dried, and then the N ₂ gas was stopped. Next, this was heat-treated at 80 ° C. for 120 minutes to be cured.

By such a drying and curing step, the fluorine-based surfactant is promptly transferred to the resin surface, and the perfluoroalkyl group is compatible with the air side and the resin-affinity portion is compatible with the resin side and is oriented. A lyophobic coating having good adhesion to the outlet and high lyophobic effect was obtained. Further, since the fluorine-based surfactant oriented on the resin surface lowers the surface friction coefficient, a lyophobic film having improved abrasion resistance could be obtained.

The contact angle and receding contact angle formed between the treated liquid-repellent film and the recording ink were measured using a contact angle meter (CA-D type manufactured by Kyowa Interface Science Co., Ltd.).
It was 50 ゜.

Here, the receding contact angle is a dynamic contact angle formed when liquid is removed from a solid surface (replace liquid / solid with air / solid), and is obtained from a droplet forming orifice of a contact angle meter. This was measured by the angle formed when the ink on the lyophobic coating was pulled back.

The recording ink used in this example is an aqueous ink composed of 60% by weight of water, 38% by weight of diethylene glycol, and 2% by weight of a dye, and has a viscosity of 2 cp and a surface tension of 40 dyne / cm.
Was used.

An ejection test was performed using the recording head obtained as described above. As a result, the ejection directionality was stable, and no ink accumulation occurred on the outer surface of the ejection port 6 even when continuous ejection was performed for a long time.

Next, a load of 200 gw / cm ² was applied to this recording head,
The ink ejection port face was reciprocated at a distance of 5 cm using gauze to rub the liquid-repellent coating, and the relationship between the number of reciprocations and the receding contact angle was examined.

As can be seen from the curve a in FIG. 3, the value of the receding contact angle did not change even after rubbing 500 times, and good results were also obtained in the continuous discharge test.

For this example, a comparative example was tested using the same recording head. The recording head of this comparative example was prepared by adding N ₂ from the ink supply port 4 to a 17% isopropyl alcohol solution of a silicone resin (for example, X12-2206 manufactured by Shin-Etsu Chemical Co., Ltd.) without adding a fluorine-based surfactant. The recording head in which gas was ejected toward the ejection port 6 at a flow rate of about 1 [l / min] was immersed for 20 seconds, dried, and then N ₂ gas was stopped. Next, this was heat-treated at 80 ° C. for 120 minutes to be cured.

The contact angle and receding contact angle formed between the treated liquid-repellent coating and the recording ink were measured using a contact angle meter (CA-D type, manufactured by Kyowa Interface Science Co., Ltd.).
36 ゜.

An ejection test was performed using the recording head of the comparative example obtained as described above. As a result, the ejection directionality was stable, and no ink accumulation occurred on the outer surface of the ejection port 6 even when continuous ejection was performed for a long time.

Next, a rubbing test was performed in the same manner as in the example, and as shown by a curve b in FIG. 3, the receding contact angle occurred with an increase in the number of frictions. At 0 degrees, the lyophobic effect disappeared. Also, when a continuous ejection test was performed using this head,
Disturbance in the ejection direction, reduction in dot size fluctuation, and the like were observed, and when ejection was further performed, the periphery of the ink ejection port was covered with ink, making ejection impossible.

 Another embodiment of the present invention will be described.

As a liquid-repellent treatment agent, X41-9710H (manufactured by Shin-Etsu Chemical Co., Ltd.) which is a silicon-based resin and has an imidoamide group
A recording head treated on the ink ejection orifice surface using a solution obtained by adding 1% of a fluorine surfactant Megafac F-177 (manufactured by Dainippon Ink and Chemicals, Inc.) to a 1% methyl cellosolve solution was designated as A. The recording head treated on the ink ejection orifice surface using a 9710H 20% methyl cellosolve solution was designated as B.

In addition, SR2410 (Toray Dow
Using a 10% toluene solution of Corning Silicone Co., Ltd. to which 1% of a fluorine-based surfactant Megafax F-177 (manufactured by Dainippon Ink and Chemicals, Inc.) was added,
The recording head treated on the ink ejection port surface is designated as C, and the resin SR
The recording head treated on the ink ejection port surface using only a 10% toluene solution of 2410 was designated as D.

Further, as a liquid repellent treatment agent, a fluorosurfactant S-382 (manufactured by Asahi Glass Co., Ltd.) was added to a 17% isopropyl alcohol solution of X12-2206 (manufactured by Shin-Etsu Chemical Co., Ltd.).
The print head treated on the ink ejection port surface using the one added with% was designated as E, and the recording head treated on the ink ejection port surface with only a 17% isopropyl alcohol solution of resin X12-2206 was designated as F.

A rubbing test similar to that of the above-described embodiment was performed on the recording heads A, B, C, D, E, and F having a lyophobic coating formed with these lyophobic materials. The result is shown in FIG. According to the experimental results, the liquid-repellent treatment film obtained by applying and curing a resin containing a fluorine-based surfactant therein has a higher liquid-repellent effect and a higher liquid-repellent treatment than a resin-only treatment film. It was confirmed that the effect maintenance characteristics were also improved.

In this embodiment, the recording head as shown in FIG. 1 has been described. However, the present invention is not limited to such a recording head, and the present invention is applicable to any type of ink jet recording head. Is the one that applies effectively.

FIG. 2 shows an ink jet recording head according to another embodiment to which the present invention is applied. In the figure, the same parts as those in FIG. In this embodiment, a pit layer 8 is provided on the heater substrate side.
As described in JP-A-62-33648, the pit layer 8 is provided with pits (concave portions) provided for the purpose of limiting the growth region of bubbles and preventing air from being caught in the nozzles. The heating element 3 is disposed at the bottom of the pit. Also in this example,
With the liquid repellent coating 7, the same effect as in the above-described embodiment was obtained.

In the above description, an inkjet recording head using an aqueous ink has been described. However, the same effect can be obtained in an inkjet recording head using an oil-based ink.

The resin and the fluorine-based surfactant used for the liquid-repellent treatment are not limited to those described in this embodiment, and appropriate ones can be selected according to the type of ink and the material of the ink ejection port. is there.

For example, when the material of the head is Si, a Si-based resin is suitable as the resin, and when a polyimide of the material of the head is used, polyimide can be used similarly as the resin. Silicon modified amide imide is a resin suitable for any of the above cases.

(Effects of the Invention) As is clear from the above description, the present invention has the following effects.

A liquid-repellent coating of an ink jet recording head having a high liquid-repellent effect can be obtained.

A liquid-repellent film having good adhesion to the material of the ink ejection port surface of the ink jet recording head can be obtained.

A liquid-repellent treatment film having improved wear resistance can be obtained.

From the above effects, the directionality of the discharged recording ink,
The ejection speed and the particle size become constant, and high-quality recording can be performed for a long time.

Furthermore, since the ink discharge port surface is less contaminated with ink,
The number of times of cleaning the ink ejection port surface can be reduced, and the recording speed can be improved.

Even if the ejection frequency is increased, good printing quality can be obtained, so that the recording speed can be improved.

And so on.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of the ink jet recording head of the present invention, FIG. 2 is a cross sectional view schematically showing another embodiment of the ink jet recording head of the present invention, and FIG.
FIG. 4 and FIG. 4 are explanatory diagrams of the experimental results. 1 ... heater substrate, 2 ... channel substrate, 3 ... heater, 4 ... ink supply port, 5 ... ink chamber, 6 ...
Ink ejection port, 7: liquid repellent coating, 8: pit layer.

Claims (1)

(57) [Claims] 1. An ink jet recording head provided with an ink ejection port for ejecting ink, wherein the end surface having the ink ejection port is made of a resin having a large adhesive force to a material of the ink ejection port, and is a fluorine-based surfactant. An ink-jet recording head, wherein a film made of a resin internally added is formed.