JPH0230540A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To enhance the water repellency and durability of a water repellent layer of a recording head by making a water repellent part around orifices of a material obtained by polymerizing and curing specific compositions. CONSTITUTION:The treatment is applied by using the following compositions to provide a water repellent layer 20 superior in water repellency and durability around orifices 14: a composition (a) containing a fluorine polymer having water- insolublity, solubility in organic solvent, and an average molecular weight of 2000 or more and a multifunctional monomer and/or multifunctional oligomer having two or more (meta)acryloyl groups in its molecule; and a composition (b) containing one or more compounds having silazine groups and one or more reaction groups selected from among groups of phloroalkyl, phloroallyl, phlorocycloalkyl, phloroalkalyl, and phloroalkylallyl. The obtained water repellent layer 20 has sufficient durability and superior adhesion to both of organic and inorganic materials.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording head whose orifice periphery is treated to be water repellent.

[Conventional technology]

2. Description of the Related Art Inkjet recording apparatuses, which perform recording by ejecting recording liquid (ink) from orifices (orifices) of a recording head, have been known as excellent recording apparatuses in terms of low noise and high-speed recording.

FIG. 2 is an exploded perspective view illustrating the configuration of a normal inkjet recording head.

In this recording head, a discharge pressure generating element 12 is installed on a substrate 11 made of glass, ceramics, etc., and the discharge pressure is generated by patterning a photosensitive resin cured film 13 by photolithography. A liquid flow path 15 and an orifice 14 corresponding to the element 12 as well as a liquid chamber 16 are formed. The photosensitive resin cured film 1
A top plate 17 made of, for example, glass, ceramics, metal, etc. is laminated and fixed on the top plate 3 with an adhesive 19. Further, a recording liquid supply port 18 is formed in the top plate 17 .

In a recording head having such a configuration, the orifice 14
surrounding the substrate 11, photosensitive resin cured film 13, and top plate 17
The physical properties of the surface of the recording liquid are extremely important for constantly and stably ejecting the recording liquid from the orifice 14. That is, if the recording liquid flows around the outer surface of the orifice 14 (the peripheral edge of the orifice) and a pool of liquid occurs in even a part of it, the recording liquid in the flow path 15 flows into the orifice 14.
When the liquid is discharged from the liquid, its flight direction deviates from the normal predetermined direction, and furthermore, due to the instability of the liquid pool, the flight direction is disturbed each time it is discharged, which is an inconvenience. Therefore, stable liquid ejection cannot be performed and good recording cannot be performed.

Furthermore, if the entire outer back surface of the orifice 14 is covered with a film of recording liquid, a so-called splash phenomenon occurs, causing scattering of the recording liquid, making it impossible to perform stable recording. Furthermore, if the liquid pool covering the outer surface of the orifice becomes large, the recording head may become unable to eject liquid.

In addition, in a normal recording head as shown in FIG. 2, the parts surrounding the orifice are made of silicon (substrate 1), glass (top plate 17), resin (cured photosensitive resin film 13), etc. Different materials are often used. The recording liquid leaks from the part of the material that is most likely to leak out of the three types at the periphery of the orifice. Among the three materials mentioned above, glass has the lowest interfacial tension with the ink for normal ink (recording liquid), so the ink leaks from that part. The glass portion is made of a commonly used material that is preferable from the viewpoint of manufacturing and performance of the head, and the use of another material for the purpose of preventing ink from leaking is undesirable from the viewpoint of manufacturing, performance, and cost.

As explained above, in the conventional recording head, if a pool of recording liquid occurs at the peripheral edge of the orifice, stable ejection becomes impossible. Moreover, this tendency becomes very noticeable when increasing the nozzle density to perform high-definition recording, or when driving at a high frequency, that is, aiming for high-speed recording, so it is important to improve the performance of the recording head. This has become a big problem.

Therefore, as shown in FIG.
Many proposals have been published in the past to solve the above-mentioned problems by forming a water-repellent layer 2o that repels ink by performing so-called water-repellent treatment on the peripheral edge of the print head 4. Various water repellent agents, such as silicone oil, are listed as water repellent agents used for this water repellent treatment.

[Problem B that the invention attempts to solve]

The water-repellent layer 20 formed on the inkjet recording head must not only have good water repellency but also have sufficient durability during normal inkjet recording to be practical. Not yet. The durability will be described below.

When performing inkjet recording, even if the orifice periphery is treated with water repellent treatment, the orifice periphery is always in contact with the recording liquid, so wipe the orifice surface with an absorbent material such as polyurethane foam. Normally, a recovery operation is performed to suck up the adhered ink. Therefore, the water-repellent layer is required to have adhesion to the extent that it will not peel off even when rubbed by an absorbent material, and wear resistance to the extent that the layer will not be destroyed. If these durability is insufficient, the water-repellent layer may gradually peel off or fall off while the head is being used, and the water-repellent layer will no longer exhibit a water-repellent effect, resulting in stable ejection. Printing becomes impossible.

In terms of the durability required for such an inkjet recording head, a water-repellent layer formed using a conventional water-repellent agent may not be sufficient.

Furthermore, when the member surrounding the orifice is made of multiple different materials, as in the inkjet head shown in Figure 2, a water-repellent layer must be formed that adheres well to all of the materials. . Water repellent layers formed using conventional water repellent agents are particularly insufficient in some cases.

The present applicant has previously applied for a water repellent treatment agent with the following properties (a) and (b) to solve such problems.

(a) Contains a substantially water-insoluble, organic solvent-soluble fluoropolymer with an average molecular weight of 2,000 or more, and a polyfunctional monomer or polyfunctional oligomer having two or more (meth)acryloyl groups in the molecule. An inkjet recording head treated with water repellent treatment using an ultraviolet curable composition.

(b) Inkjet recording treated with water repellency using a compound having a silazane group and one or more reactive groups selected from the group consisting of a fluoroalkyl group, a fluoroallyl group, a fluorocycloalkyl group, a fluoroalkaryl group, and a fluoroalkylaryl group. head.

For example, the water repellent layer of the above-mentioned normal head (substrate 11 is silicon, top plate 17 is glass, resin cured film 13) is (a
) or (b), it is possible to obtain a water-repellent layer with improved durability than when conventional water-repellent agents are used.

However, although the composition described in (a) shows particularly excellent adhesion to the photosensitive resin cured film, it has poor adhesion to inorganic materials such as glass and silicon. However, it is still not enough, and if used for a longer period of time, it may start to peel off and the water repellent effect may decrease.

On the other hand, the composition described in (b) is the opposite, and shows particularly excellent adhesion to glass and silicone, or has poor adhesion to organic materials such as resin. It wasn't enough.

The inkjet recording head having the configuration shown above is
It is composed of multiple types of organic and inorganic materials from the viewpoint of manufacturing, performance, cost, etc. Therefore, the above (a)
For (b), there was room for further improvement in the practical performance of adhesion to both organic and inorganic materials.

The present invention has been made to solve such problems, and its purpose is to provide an inkjet recording head having a water-repellent treatment layer with excellent water-repellency and durability.

[Means for Solving the Problems] The present invention provides an inkjet recording head in which at least the peripheral edge of the orifice has been subjected to water repellent treatment, in which the water repellent treated portion comprises a polymerized cured product of the following composition (a) and a composition (
An inkjet recording head characterized by having the polymerized cured product of b).

Composition (a): A water-insoluble, organic solvent-soluble fluoropolymer with an average molecular weight of 2.000 or more, and two or more (meth) molecules in the molecule.
A composition comprising a polyfunctional monomer and/or a polyfunctional oligomer having an acryloyl group.

Composition (b) contains one or more compounds having a silazane group and one or more reactive groups selected from the group consisting of a fluoroalkyl group, a fluoroallyl group, a fluorocycloalkyl group, a fluoroalkaryl group, and a fluoroalkylaryl group. Composition.

By performing both the treatments using the compositions (a) and (b), the recording head of the present invention can be used even when the peripheral portion of the olefin is composed of a plurality of organic and inorganic materials. Also, the durability of the water-repellent layer is sufficient, and therefore the recording head is capable of stable ejection printing.

In addition, the water-repellent treatment layer here refers to a part on the surface of the water-repellent part in the present invention where a cured product is formed, and when it is not layered, for example, the cured product is uniform or non-uniform. This also includes cases where they are scattered.

The treatments using the compositions (a) and (b) may be performed first. Then, (b) first, (a
) is preferably carried out later. Note that once a water repellent treatment is applied to a certain surface, that is, once a water repellent layer is formed, that surface becomes water repellent, so a second water repellent layer is applied to that surface. Even if you try to laminate them together, the layers usually don't adhere well. In the examples of the present invention described below, excellent adhesion (that is, the main effect of the present invention) has been demonstrated that is unexpectedly good from the common knowledge in the technical field related to such water repellent treatment.

Hereinafter, the compositions (a) and (b) of the present invention and treatments using the same will be explained in detail.

The composition (a) is not particularly limited as long as it contains the above-mentioned fluoropolymer or monomer, but it may have excellent water repellency, etc., which is necessary for the periphery of the orifice of the inkjet recording head as described above. It is preferable to use a material that can easily form a water-repellent layer, such as the photo-radical polymerizable resin composition DEFENSA7702 (trade name, manufactured by Dainichi Ink Chemical Industries, Ltd.).

The composition (b) is not particularly limited as long as it contains one or more of the compounds having the above-mentioned reactive groups;
It is desirable to have a material that can easily form a water-repellent layer with excellent water repellency, etc. required for the periphery of the orifice of an inkjet recording head, such as CF3 (
CF2)4S, l (Nl2)3, CF3 (CF2
) 4si (Nl2) 2NH5i (Nl2) 2
(GFz) 4CF3 etc. can be mentioned as a suitable example.

〔Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 1-1 As shown in FIG. 2, a heating element (discharge pressure generating element) 2 was provided on a silicon substrate 11.
Although not shown in FIG. 2, conductive wiring is provided at both ends of the heating element 12 for sending signals to the heating element. Next, a photosensitive dry film 13 (manufactured by Tokyo Ohka, DF Odile) is laminated on this substrate 1], and then a well-known photolithography processing method is used to process the photosensitive dry film 13.
An orifice 14, a flow path 15, and a liquid chamber 16 were formed.

Furthermore, a photosensitive resin cured film 13 is attached to a glass top plate 17 with a recording liquid supply port 18 through an adhesive 19.
+ was laminated and glued.

The inkjet recording head constructed as described above was placed in a UV103 cleaning bath, and the surface including the orifice 14 was cleaned.

Next, each flow path 15 is filled with distilled water to form CF3 (CFz)4Sj (Nl2) as the first water repellent agent.
3 and CF3 (CF2) 4S i (Nl2) 2
It was immersed in a 2% by weight Freon TF (Daiflon 5-3, manufactured by Daikin) solution of a mixture of NH5i (Nl2) 2 (CF2) 4CF3, pulled up, and air-dried.

Thereafter, distilled water was removed into each channel 15, and the reaction was cured at 100° C. for 30 minutes.

Next, a photo-radical polymerizable resin composition DEFENSA7702 (Dainippon Ink & Chemicals, trade name) as a second water-repellent treatment agent was immersed in a solution diluted 100 times with Freon TF, taken out, and air-dried. Thereafter, the resin composition was cured by irradiating UV light at IOJ/cm2 to complete an inkjet recording head of the present invention as shown in FIG.

Example 2 An ink jet recording head of the present invention was produced in the same manner as in Example 1 except that the first water repellent treatment and the second water repellent treatment were performed in reverse order.

Example 3 Kano s (CF2)4S+ (N
l2) Except for using 5 wt% Freon TF solution in 3.
An inkjet recording head of the present invention was produced in the same manner as in Example 1.

Example 4 An inkjet recording head of the present invention was produced in the same manner as in Example 3, except that the first water repellent treatment and the second water repellent treatment were performed in reverse order.

Comparative Example 1 An inkjet recording head was produced in the same manner as in Example 1 except that the first water repellent treatment was not performed.

Comparative Example 2 An inkjet recording head was produced in the same manner as in Example 1 except that the second water repellent treatment was not performed.

Evaluation of durability: A wear durability test was conducted on the inkjet recording heads produced in Examples 1 to 4 and Comparative Example 1.2 as follows.

FIGS. 3(a) and 3(b) are a perspective view and a plan view showing an outline of the abrasion durability test.

As shown in this figure, a silicone rubber plate 21 is held by a member 22, and the member 22 is held about a rotating shaft 23.
By rotating, the silicone rubber plate 21 weighs approximately 10g.
The water-repellent layer 20 of the inkjet recording head 1 is rubbed with a pressure of /cm2. Further, ink droplets 25 can be dropped from the ink dripping device 24 onto the rubbing portion so that the rubbing becomes close to the actual use condition.

Using this device, a durability test was conducted at an ink dropping rate of 1 drop/second. ．． It was performed 000 to 20,000 times.

At that time, 1,000 times, 5,000 times, 10,000 times,
After 20,000 times, each head was removed, printing was performed, and the condition was observed. The results are shown in Table-1.

In addition, each mark shown in Table 1 indicates the condition of the printing obtained. ○ indicates that the printing condition is good, △ indicates that the printing condition is normal, and × indicates that the printing condition is poor. The quality of the print was judged by both measuring the amount of deviation of the dot landing points and visually performing a sensory test.

Table 1 As is clear from the results shown in Table 1, the print quality of the recording head of the comparative example deteriorated after being rubbed 5,000 times. This is because the water repellent layer peels off. In comparison, the heads of Examples 1 to 4 had good or average print quality even after being rubbed 20,000 times.

〔Effect of the invention〕

As explained above, in the inkjet recording head of the present invention, a water-repellent treatment layer with excellent water-repellency and durability is formed around the orifice, so stable ejection printing is always possible and good printing is possible. can get.

In addition, compared to conventional water-repellent layers, the water-repellent layer has excellent adhesion to both organic and inorganic materials among the above-mentioned durability, and therefore has excellent adhesion to both organic and inorganic materials. It is particularly useful for use in conventional recording heads where the material is used as an orifice construction material.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating the appearance of an inkjet recording head, FIG. 2 is a developed perspective view illustrating the configuration of the inkjet recording head, and FIGS. FIG. 2 is a perspective view and a plan view showing an overview of a durability test conducted on an example inkjet recording head. 1... Inkjet recording head 11... Substrate 12... Discharge pressure generating element 13... Photosensitive resin cured film 15... Channel 17... Top plate 20... Water repellent treatment layer 22 ... Holding member 24 ... Ink dripping device 14 ... Orifice 16 ... Liquid chamber 19 ... Adhesive 21 ... Silicone rubber plate 23 ... Rotating shaft 25 ... Ink

Claims (1)

Scope of Claims: In an inkjet recording head in which at least the peripheral edge of the orifice has been subjected to water repellent treatment, the water repellent treatment portion may contain a polymerized cured product of the following composition (a) and a polymerized cured product of the composition (b). An inkjet recording head comprising: Composition (a): A water-insoluble, organic solvent-soluble fluoropolymer with an average molecular weight of 2,000 or more and two or more (meth) molecules in the molecule.
A composition comprising a polyfunctional monomer and/or a polyfunctional oligomer having an acryloyl group. Composition (b): one or more compounds having one or more reactive groups selected from the group consisting of a fluoroalkyl group, a fluoroallyl group, a fluorocycloalkyl group, a fluoroalkaryl group, and a fluoroalkylaryl group and a silazane group. A composition comprising.