JPH04339656A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To provide an ink jet recording head preventing the adhesion of emitted ink to the vicinity of an ink emitting orifice, having good ink resistance and capable of performing stable recording of high quality over a long period of time. CONSTITUTION:An ink repelling layer 5 of fluoroplastic coprecipitation plating due to an electrolytic method is provided to a member 3 forming a surface having an ink emitting orifice 4 in an ink jet recording head. When an ion such as Li<+>, Na<+>, K<+>, Ca<2+>, Cl<->,SO4<2->, SO3<2->, NO3<-> or NO2<-> is mixed with ink 2 as impurity, the ink repelling layer 5 of the surface having the ink emitting orifice is not deteriorated by the ink and both of ink repellency and ink resistance are satisfied.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording head for an inkjet recording apparatus that forms an image on a recording medium by ejecting ink droplets.

0002

[Prior Art] Inkjet recording is a non-impact recording method that produces low noise during recording among the various recording methods currently known, and is also a high-speed method because it forms images on a recording medium by flying ink droplets. It is recognized as an extremely useful recording method in that it can record on plain paper without requiring any special fixing treatment. In an inkjet recording head as shown in FIG.
The member 3 forming the surface having ink ejection ports is, for example,
It is made of metal, ceramic, silicon, glass, plastic, etc. However, since the inkjet recording method forms an image on the recording medium by ejecting ink droplets, in the case of an inkjet recording head that does not wet the ink ejection surface, the ink repellency of the surface with the ink ejection ports ( Water-based ink requires water repellency; oil-based ink requires oil repellency). If the ink repellency is insufficient, when ink is ejected from the inkjet recording head, the ink will adhere to the vicinity of the ejection ports, resulting in uneven ink pooling (uneven wetting), as shown in Figure 2. Therefore, when ink is ejected again, a problem arises in that the flying direction is pulled toward the ink pool and deviates from the normal direction (flight bending), as shown in FIG. Furthermore, because the wetting unevenness is unstable, the flying direction of ink is disturbed each time it is ejected, making it impossible to stably eject ink and obtaining good recording.

[0003] Conventionally, therefore, various methods have been attempted to improve ink repellency by subjecting part or all of the surface having ink ejection ports to a surface treatment.

Among these, Ni/fluorocarbon polymer eutectoid plating by an electroless method disclosed in Japanese Patent Application Laid-open No. 2-55140 was particularly effective.

[0005]

However, when an ink containing a dye is used as an inkjet recording ink, Li+, Na+, K+, Ca2+,
Cl-, SO42-, SO32-, NO3-, NO2-
ions such as these are mixed in as impurities. Furthermore, since the ink flow path and ink ejection surface of an inkjet recording head are always in contact with ink, ink resistance is also required.
i/fluorocarbon polymer eutectoid plating has a problem in that when the inkjet recording ink contains a dye, the electroless Ni/fluorocarbon polymer eutectoid plating surface is corroded by the above ions. therefore,
When using electroless Ni/fluorocarbon polymer eutectoid plating to increase the ink repellency of the surface with the ink ejection port, if the plated surface is in contact with ink for a long period of time, the plated surface may peel or crack, resulting in the ink repellency of the ink ejection surface being increased. There was a problem with the loss of gender.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its purpose is to prevent ink from adhering to the vicinity of the ejection openings and to maintain durability when ink is ejected from an inkjet recording head. An object of the present invention is to provide an inkjet recording head that has good ink properties and can perform stable, high-quality recording for a long period of time.

[0007]

[Means for Solving the Problems] The present invention is characterized in that an inkjet recording head has an ink-repellent layer of fluorine-based polymer eutectoid plating formed by an electrolytic method on the outer surface of the surface having ink ejection ports.

Generally, the surface of an inkjet recording head having ink ejection ports is made of metal, ceramic, silicon, glass, plastic, or the like. Preferred materials include titanium, chromium, iron, cobalt, nickel,
Copper, zinc, tin, gold, etc., or alloys such as nickel-phosphorus alloy, tin-copper-phosphorus alloy (phosphor bronze), copper-zinc alloy (BS), stainless steel (SUS), polycarbonate, polysulfone, ABS Examples include resin (acrylonitrile/butadiene/styrene copolymer), polyethylene terephthalate, polyacetal, etc.

The present inventors used an ink that has good adhesion to the material of the surface having the ink ejection ports, has good ink repellency, and contains a dye as an inkjet recording ink. Li+, Na+, K+, Ca2
+, Cl-, SO42-, SO32-, NO3-, NO
As a result of examining surface treatments that minimize deterioration of the ink-repellent layer when ions such as 2- are mixed as impurities,
It has been found that both ink repellency and ink resistance can be satisfied by providing a surface treatment layer of fluorine-based polymer eutectoid plating by electrolytic method on the surface having ink ejection ports.

[0010] In the present invention, polytetrafluoroethylene (PTFE), polyperfluoroalkoxybutadiene (PFA), polyfluorovinylidene, polyfluorovinyl, etc. may be used alone or in combination as the fluorine-based polymer. can.

Further, the matrix of the plating layer is not particularly limited and may be selected from any suitable metal such as nickel, copper, silver, zinc, tin, etc., but preferably nickel (N
i), nickel-cobalt alloy (Ni-Co), nickel-phosphorus alloy (Ni-P), nickel-boron alloy (N
Nickel alloys such as i-B) are selected because they have excellent surface hardness and wear resistance.

Furthermore, the thickness of this fluorine-containing polymer eutectoid plating layer is suitably in the range of 1 to 10 μm. If the layer is thinner than this, the ink repellency of the surface having the ink ejection orifice will be insufficient, and if the layer is thicker than this, the accuracy of the diameter of the ink ejection orifice will be affected.

By providing the above-mentioned surface treatment layer, when ink is ejected from the inkjet recording head, the ink does not adhere to the vicinity of the ink ejection opening, and as shown in FIG.
Also, the ink ejection state as shown in FIG. 5 can be maintained. Furthermore, stable high-quality recording can be performed for a long period of time without deterioration due to ink.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of an inkjet recording head according to the present invention. Inkjet recording head materials of the present invention include metals, ceramics,
Examples include silicon, glass, plastic, etc., and the member 3 forming the surface having ink ejection ports and the ink flow path forming member 1 may be made of the same material, and for example, the material forming the surface having the ink ejection ports may be the same. The member 3 may be made of metal, and the ink flow path forming member 1 may be made of plastic.

In the ink jet recording head of the present invention, a fluorine-containing polymer eutectoid plating layer is formed by electrolytic method on the surface of the head having the ink ejection ports prepared in advance, and an ink-repellent surface treatment layer 5 is provided. Can be done. Also,
Separately create the surface with the ink ejection port and the ink flow path,
It is also possible to provide an ink-repellent surface treatment layer 5 of a fluorine-based polymer eutectoid plating layer on the outer surface of the surface having the ink ejection openings by an electrolytic method, and then bond it to the ink flow path forming member.

Furthermore, if the fluorine-containing polymer eutectoid plating layer 5 is too thin, the ink repellency of the surface having the ink ejection port will be insufficient, and if the plating layer is too thick, the ink ejection port will be damaged. 1 to 10μ as it affects the accuracy of the diameter.
A range of m is appropriate. At this time, the amount of fluorine-based polymer eutectoid plating in the plating layer is 5 to 60 vol with respect to the plating layer.
%, particularly preferably 10 to 50 vol%.

The present invention is not limited to the head shown in FIG. 1, but can be applied to any type of head that ejects liquid from an ink ejection port.

Next, the surface treatment methods of Examples and Comparative Examples of the present invention will be described in more detail.

Example 1 An ink-repellent layer was formed on the outer surface of a Ni plate on which ink discharge ports were formed by electrolysis using a plating solution having the following composition under the following conditions.

・Plating composition Nickel sulfate (NiSO4.6H
20) 240g/l
Nickel chloride (NiCl2.6H2O)
45g/l boric acid (H
3BO3)
35g/l PTFE

50g/l ・Condition pH
4.0-4.5
plating temperature
60℃
cathode current density
3A/dm2
stirring
The ink ejection plate obtained by gentle mechanical agitation was adhered to an ink channel formed of polycarbonate resin to form an inkjet recording head.

Example 2 The outer surface of a phosphor bronze (Sn-Cu-P) plate on which ink discharge ports were formed by drilling holes with a press was plated using a plating solution with the following composition under the following conditions.
An ink-repellent layer was formed.

・Plating composition Nickel sulfamate (Ni(
NH2SO3)2) 70g/l H3
BO3
30g/l
PTFE

55g/l ・Condition pH
4.0-4.5
plating temperature
50℃
Cathode current density
2A/dm2
stirring
Gentle mechanical stirring then 35
Place it in a 0℃ oven for 30 minutes to melt the PTFE particles exposed on the surface of the eutectoid plating layer, and transform the plating surface into PTFE.
covered completely.

[0024] The obtained ink ejection plate and an ink channel formed of polysulfone resin were adhered to form an inkjet recording head.

Example 3 After chemically etching a polycarbonate resin substrate,
An ink-repellent layer was formed by sputtering Ni and plating the Ni sputter layer of a polycarbonate substrate with the same plating solution and plating conditions as in Example 2. A penetrating hole was made in this substrate by excimer laser processing to form an ink ejection plate.

Next, the obtained ink ejection plate and ink channels formed of polycarbonate resin were adhered to form an inkjet recording head.

Comparative Example 1 Electroless Ni-P/PTFE composite plating was performed on the outer surface of a Ni plate on which ink discharge ports were formed by electrolytic method using a plating solution having the following composition and under the following conditions.
An ink repellent layer was formed.

・Plating composition NiSO4・6H2O
55
g/l Sodium hypophosphite (N
aPH2O2) 20g/l
Sodium citrate (Na3C6H
5O7) 10g/l
PTFE
3.5g/l
・Condition pH
5.0-5.5
plating temperature
90℃
stirring
Gentle mechanical stirring, then 3
Place it in a furnace at 80℃ for 30 minutes to melt the PTFE particles exposed on the surface of the eutectoid plating layer, and transform the plating surface into PTF.
Completely covered with E.

Next, the obtained ink ejection plate and ink channels formed of polycarbonate resin were adhered to form an inkjet recording head.

Comparative Example 2 After chemically etching a polycarbonate resin substrate,
Using the same plating solution and plating conditions as Comparative Example 1, electroless Ni-
An ink-repellent layer was formed by P/PTFE composite plating. A penetrating hole was made in this substrate by excimer laser processing to form an ink ejection plate.

Next, the obtained ink ejection plate and a flow path formed of polycarbonate resin were adhered to form an inkjet recording head.

Considering the case where the inkjet recording head is attached to the printer body or shipped and stored as a single head, the warranty period must be 2 to 10 years from the time of manufacture. Since it can be substituted by leaving it in a constant temperature bath for 5 days, it was used as a standard for evaluating ink resistance.

[0033] Therefore, the above Examples 1 to 3 and Comparative Example 1
Using the ink ejection plate and inkjet recording head of 2 to 2 and inks A, B, and C having the following compositions,
The following experiment was conducted to confirm the ink resistance of the ink repellent layer. Table 1 also shows the total ion concentrations of inks A, B, and C.

Note that % in the text is based on weight.

Composition of Ink A C. I. direct black 154
1%
glycerin
3%
ethanol
5%
water

91% Ink B composition Food Black 2
2%
glycerin

5% 1-propanol

5% water

88% Composition of Ink C C. I. directed black 19
2%
diethylene glycol
15% 2-propanol
10% water

73%

0036
]

[Table 1]

Test I: The contact angles of inks A, B, and C with respect to the ink ejection plates of Examples 1 to 3 and Comparative Examples 1 and 2 were measured, and then the contact angles were applied to inks A, B, and C, respectively. After being immersed and left in a constant temperature bath at 70° C. for 5 days, the state of the ink-repellent layer was visually confirmed, and the contact angles with Inks A, B, and C were measured again. The results are shown in Table 2.

[0038] The contact angle is F, manufactured by Kyowa Interface Science Co., Ltd.
Measurements were made using an ACE automatic contact angle meter PD-Z type at 25° C. 60 seconds after dropping the ink.

Test II: The ink channels of the inkjet recording heads of Examples 1 to 3 and Comparative Examples 1 and 2 were filled with the following hydrophilic treatment solution and left in a constant temperature bath at 70° C. for 24 hours. After performing a hydrophilic treatment to prevent air bubbles from forming, each of the inks A, B, and C was filled and left in a constant temperature bath at 70° C. for 5 days.

Hydrophilic treatment solution diethylene glycol
99%C. I. direct black 154
1% Next, it was installed in an inkjet recording apparatus in which the ink ejection element 6 shown in FIG. 1 is a piezoelectric element. After one page has been continuously printed, the printer waits for 30 seconds and prints again, and then the printing condition is checked, and the presence or absence of flight curves is checked, and judgment is made according to the following criteria.

[0041] Does not bend at all
◎It bends a little, but it does not affect the characters.
○Curving occurs and affects the characters △Severely curved characters cannot be read ×
The results are shown in Table 3.

[0042]

[Table 2]

[0043]

[Table 3]

As described above, when the ink-repellent layer (Comparative Examples 1 and 2) of fluorine-containing polymer eutectoid plated by electroless method on the surface having the ink ejection opening, the plated surface peeled off after being immersed in the ink.
Cracks, etc. are observed, the contact angle is low, and flight bending occurs. However, in the case of the present invention, in which an ink-repellent layer of eutectoid plating of fluorine-based polymer is provided on the surface having the ink ejection port by electrolytic method, no peeling or cracking of the plated surface was observed even after immersion in the ink, and no contact was observed. There were no problems with corners or flight bends.

[0045]

According to the present invention as described above, the ink resistance of the ink-repellent layer on the surface having ink ejection ports is improved, and the ink jet recording head is not deteriorated by ink. Therefore, it is possible to provide an inkjet recording head that has good ink resistance, can perform stable high-quality recording for a long period of time, and has excellent reliability.

[Brief explanation of drawings]

FIG. 1 A schematic cross-sectional view of an inkjet recording head of the present invention.

FIG. 2 is a diagram illustrating a conventional inkjet recording head.

FIG. 3 is a diagram illustrating a conventional inkjet recording head.

[Figure 4] Schematic diagram showing the effects of the present invention

[Fig. 5] Schematic diagram showing the effects of the present invention

[Explanation of symbols]

1: Ink flow path forming member 2: Ink flow path 3: Member forming a surface having ink ejection ports 4: Ink ejection port 5: Ink-repellent layer of fluorine-based polymer eutectoid plating by electrolytic method 6: For ink ejection Element 7: Drive line 8: Ink

Claims (1)

[Claims] Claim 1: In an inkjet recording head,
An inkjet recording head characterized by having an ink-repellent layer of fluorine-based polymer eutectoid plating formed by electrolytic method on the outer surface of the surface having ink ejection ports.