JP3110314B2 - Hydrophilization treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a hydrophilic treatment method.

[0002]

2. Description of the Related Art A plurality of grooves are provided on the upper surface of a piezoelectric body, and a lid is adhered to the upper surface of the piezoelectric body. An ink jet head that performs printing by discharging ink droplets from a nozzle hole onto printing paper is described in, for example, JP-A-4-30725.

[0003] Most of such ink-based members such as lids of ink jet heads are made of plastics due to moldability, cost, and other required characteristics. It is an essential condition that the surface of the ink member of the ink jet head has high wettability for reasons of reliability such as print quality. However, plastics generally have low surface energy and thus have the property that liquids are difficult to wet, and the wettability is not sufficient.

[0004]

Means for improving the wettability of the plastic surface include surface modification by oxygen plasma treatment or short-wavelength ultraviolet irradiation treatment, but the process is complicated and the effect is persistent. Had a problem.

[0005] In addition, there is a serious problem that the wettability is significantly deteriorated due to surface contamination due to generation of gas in the curing step of the adhesive after the hydrophilic treatment.

SUMMARY OF THE INVENTION An object of the present invention is to improve the wettability of the surface of an ink-based member of an ink jet head by a simple method, thereby preventing a decrease in printing quality and ensuring higher reliability.

[0007]

In order to solve the above problems, an ink jet head according to the present invention employs the following configuration.

The surface of an inkjet head component is subjected to a hydrophilization treatment by performing a sulfur peroxide treatment, a treatment with a diethanolamine solution is performed after the treatment with the sulfur peroxide, and an acid treatment is performed after the hydrophilicity of the member surface is deteriorated. For performing a hydrophilization regeneration treatment.

In the present invention, the surface of the ink-based member is subjected to sulfuric acid-hydrogen peroxide treatment. Sulfuric acid is a strong acid and destroys the plastic of the ink-based member, so that a hydroxyl group or a carboxyl group, which is a hydrophilic group, is formed on the surface of the member.

Further, the surface of the ink member is treated with a diethanolamine solution. When treated with a diethanolamine solution, carboxyl groups and hydroxyl groups formed on the surface of the ink-based member and diethanolamine undergo hydrogen bonding via hydrogen atoms of the hydroxyl groups and carboxyl groups. Since diethanolamine is bonded to the hydroxyl group and carboxyl group on the surface of the ink-based member, the polarity increases, and the wettability also increases.

Thereafter, contaminants such as gas generated in the curing step of the adhesive are adsorbed or bonded to diethanolamine hydrogen-bonded to a hydrophilic group on the surface of the ink member, thereby contaminating the surface of the ink member. Hydrogen bonds are much weaker than covalent bonds, and can be easily broken with a weaker acid than sulfuric acid. When the surface of the ink member is treated with acid, diethanolamine and contaminants are cut off from the hydroxyl group and carboxyl group on the surface of the ink member, that is, removed from the surface of the ink member, and the hydroxyl group and carboxyl group, which are hydrophilic groups on the surface of the ink member again. Is restored and the wettability is regenerated.

Further, when treated with a diethanolamine solution, the polarity of the hydrophilic group increases and the wettability of the surface of the ink-based member becomes higher. In this way, the wettability is restored, and a decrease in print quality is prevented, and higher reliability can be secured.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing the structure of an ink jet head according to the embodiment.

The piezoelectric element 16 is bonded to the base 10. The vibration plate 10 is bonded to the base 10 and the piezoelectric element 16.

Ink chamber component 1 having ink chamber 15
Reference numeral 4 is formed of a plastic containing a filler (here, a thermosetting epoxy resin).

As the hydrophilic treatment, the ink chamber constituent member 14 is used.
Is immersed in sulfuric acid and water at room temperature (liquid obtained by mixing 96% of sulfuric acid and 30% of hydrogen peroxide at a volume ratio of 8: 1) for 15 minutes. The sulfuric acid water destroys the plastic on the surface of the ink chamber constituent member 14.

The ink chamber constituent member 14 is pulled up from the sulfuric acid solution and ultrasonically cleaned with pure water. Further, moisture on the surface is blown off by nitrogen blow and dried.

The surface of the plastic is destroyed by the sulfuric acid and water to form carboxyl groups and hydroxyl groups, which are hydrophilic groups. Therefore, the wettability of the surface of the ink chamber constituting member 14 is improved.

Further, when the ink chamber constituent member 14 is treated with a diethanolamine solution diluted to a concentration of 20% with pure water, the hydroxyl groups and carboxyl groups on the surface of the ink chamber constituent member 14 and diethanolamine are bonded by hydrogen bonds. The surface of the ink chamber constituting member 14 has an increased polarity and a higher wettability due to the binding of diethanolamine to the hydroxyl group and the carboxyl group.

The ink chamber constituting member 14 is adhered to the vibration plate 10 and a nozzle plate having a nozzle hole 13 (here, SUS3
04 is bonded to the ink chamber constituting member 14 and the base 10. Contaminants such as gas generated during the curing process of the adhesive are adsorbed or bonded to diethanolamine hydrogen-bonded to hydroxyl groups and carboxyl groups on the surface of the ink chamber 15.

After the step of curing the adhesive, the surface of the ink chamber 15 is subjected to an acid treatment to perform a hydrophilicity regenerating treatment. By acid-treating the surface of the ink chamber 15, the ink chamber 15
Hydrogen bonds between hydroxyl and carboxyl groups on the surface and diethanolamine are broken, and contaminants are removed from the surface of the ink chamber 15 together with diethanolamine.

Hydrogen bonds are much weaker than covalent bonds and can be easily cleaved with a weaker acid than sulfuric acid. As the acid, a diluted sulfuric acid solution, which is a solution obtained by diluting sulfuric acid solution with pure water (sulfuric acid 96%, hydrogen peroxide 30%, and pure water at a volume ratio of 10:
1:15).

Contaminants are removed from the surface of the ink chamber 15 together with diethanolamine, the hydroxyl groups and carboxyl groups are restored, and the wettability is regenerated. Further, the surface of the ink chamber 15 is treated with a diethanolamine solution diluted to 20% with pure water. Then, as described above, the hydroxyl group and the carboxyl group on the surface of the ink chamber 15 are hydrogen-bonded to the diethanolamine, so that the polarity of the surface of the ink chamber 15 is increased and the wettability is further improved.

After the hydroxyl groups and carboxyl groups on the surface of the ink chamber 15 have been restored, the ink chamber 1 is washed with a sodium hydroxide solution.
Five surfaces can also be treated. In that case, ink chamber 1
5 Hydrogen atoms of hydroxyl groups and carboxyl groups on the surface are replaced by sodium atoms of sodium hydroxide, and the ink chamber 15
The polarity of the surface is higher. As a result, the wettability of the surface of the ink chamber 15 is improved.

The following evaluation was performed to confirm the effect of improving the wettability.

<Evaluation> Using a flat plate of the same member as the ink chamber constituting member 14, a hydrophilic treatment was performed under the same conditions as in the embodiment.
Exposure to the atmosphere during the curing process of the modeled adhesive,
A hydrophilization regeneration treatment was performed under the same conditions as in the example, and the contact angle with pure water was measured as an evaluation example.

The atmosphere during the curing process of the adhesive is ink chamber 1
The ratio of the volume of the container 5 to the amount of the adhesive applied was determined, and the container formed of a flat plate of the same member as the ink chamber component 14 having a size capable of measuring the contact angle with pure water was used. The increased amount of adhesive to the same ratio as was cured and modeled.

The term "contact angle" refers to the case where pure water 21 is dropped on a horizontally fixed plate 22 shown in FIG. 2, and the diameter of the surface of the droplet in contact with the plate is set to (2 × R). Let the height of the droplet from the plate surface be H. At this time, tanα = H
As / R, θ when θ = 2 × α is defined as the contact angle.

The measurement results of the contact angle are shown below.

The contact angle after the treatment with the sulfur-peroxide solution was 10 ° or less, and the contact angle was not more than 10 ° after the treatment with the diethanolamine solution after the treatment with the sulfur-peroxide solution. The contact angle after exposure to the atmosphere during the curing of the adhesive was 61 degrees. The contact angle after the treatment with the diluted sulfuric acid was 26 degrees, and the contact angle after the treatment with diethanolamine performed after the treatment with the diluted sulfuric acid was 10 degrees or less.

[0032]

As is apparent from the above description, according to the present invention, the print quality is prevented from deteriorating and the reliability is improved by improving the wettability of the surface of the ink member of the ink jet head by a simple method. Is to ensure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of an inkjet head according to the present invention.

FIG. 2 is an explanatory diagram of a contact angle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Base 11 Vibration plate 12 Nozzle plate 13 Nozzle hole 14 Ink chamber constituent member 15 Ink chamber 16 Piezoelectric element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-63840 (JP, A) JP-A-5-85894 (JP, A) JP-A-7-206600 (JP, A) JP-A-7-206 266553 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/16 C08J 7/14

Claims (3)

(57) [Claims] 1. An ink jet head for recording characters and images using liquid ink, wherein a surface of a member constituting the ink jet head is treated with sulfuric acid and hydrogen peroxide, which is a mixed solution of sulfuric acid and hydrogen peroxide, to obtain a sulfuric acid. A hydrophilization treatment method, wherein a treatment with a diethanolamine solution is performed after a treatment with water permeation, and an acid treatment is performed after the hydrophilicity of the member surface is deteriorated. 2. The hydrophilization treatment method according to claim 1, wherein the acid treatment is a treatment with a diluted sulfuric acid solution, which is a solution obtained by diluting the sulfuric acid solution with pure water. 3. The method according to claim 1, wherein a treatment with a sodium hydroxide solution or a diethanolamine solution is performed after the acid treatment.