Patent Grant
10189253
The disclosure relates to a liquid ejection head and a method for producing the liquid ejection head.
Liquid ejection heads configured to eject liquid are applied to, for example, inkjet recording heads configured to eject ink onto a recording medium to thereby perform recording. In general, an inkjet recording head includes fine ejection orifices and channels, and plural energy generating elements configured to eject ink. In recent years, inkjet recording heads have come to be designed so as to have a large number of ejection orifices, and so as to eject ink droplets having a small size. As a result, some ink droplets that are ejected but do not contribute to printing have come to be no longer negligible. Specifically, for example, ink droplets that are to impact on recording media are each divided into plural droplets (a main droplet and satellite droplets), so that the formed images have poor quality; and ink droplets lose velocity and become floated before impact on recording media, and these floating ink droplets (hereafter mist) adhere to members of the recording apparatus and are transferred onto recording media. Japanese Patent Laid-Open No. 2011-207235 has disclosed that protrusions are formed within an ejection orifice and ink is held between the protrusions. This configuration enables a decrease in the length of tails of ink droplets upon ejection and a reduction in the amount of satellite droplets and mist.
The disclosure provides a liquid ejection head that enables a reduction in the amount of satellite droplets and mist to improve printing quality, and also enables an improvement in ejection stability at the time of restarting of liquid ejection.
A liquid ejection head according to an embodiment of the disclosure includes a substrate; and an ejection orifice-forming member formed on the substrate and including an ejection orifice configured to eject liquid and a liquid channel communicating with the ejection orifice, wherein the ejection orifice-forming member includes an ejection orifice-forming member layer A, an intermediate water-repellent layer, and an ejection orifice-forming member layer B in this order from a substrate-side of the member, the ejection orifice-forming member includes a protrusion protruding into the ejection orifice, and the ejection orifice-forming member includes a water-repellent projection portion that is at least a portion of the intermediate water-repellent layer and that projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B.
A method for producing a liquid ejection head according to an embodiment of the disclosure includes a step of forming, on a substrate, a shape member used for forming a liquid channel and formed of a channel-forming resin composition; a step of forming, on the shape member and the substrate, a layer that is formed of a photosensitive resin composition A and that is curable into an ejection orifice-forming member layer A; a step of forming, on the layer formed of the photosensitive resin composition A, a layer that is formed of a photosensitive resin composition C and that is curable into an intermediate water-repellent layer; a step of forming, on the layer formed of the photosensitive resin composition C, a layer that is formed of a photosensitive resin composition B and that is curable into an ejection orifice-forming member layer B; a step of exposing the layer formed of the photosensitive resin composition A, the layer formed of the photosensitive resin composition C, and the layer formed of the photosensitive resin composition B, to form a pattern of an ejection orifice for ejecting liquid, a protrusion protruding into the ejection orifice, and a water-repellent projection portion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition A, the layer formed of the photosensitive resin composition C, and the layer formed of the photosensitive resin composition B; and a step of removing the shape member, wherein the water-repellent projection portion is at least a portion of the intermediate water-repellent layer, and projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B.
Further features and aspects of the disclosure will become apparent from the following description of numerous example embodiments with reference to the attached drawings.
The protrusions within ejection orifices disclosed in Japanese Patent Laid-Open No. 2011-207235 enable a reduction in the amount of satellite droplets and mist. However, formation of such protrusions in an ejection orifice results in an increase in the length of the periphery of the ejection orifice, which results in an increase in the forward resistance within the ejection orifice.
There are some cases where, after termination (for some time) of printing using ink droplets ejected from an inkjet recording head, printing restarted is not appropriately performed because ink droplets are not ejected or ink droplets do not go straight and do not impact on the intended positions on printing media. Such defective ejection at the time of restarting of ejection is probably caused because, during termination of printing, ink within the ejection orifices has evaporated, which results in an increase in the ink viscosity.
Another factor that causes the defective ejection at the time of restarting of ejection is the above-described forward resistance within the ejection orifices. In other words, when the forward resistance within ejection orifices is excessively high, ink is less likely to be ejected and defective ejection is likely to occur. With ejection orifices having protrusions, in order to provide the effect of reducing the amount of satellite droplets and mist, liquid needs to be held with the protrusions at the time of ejection. For this reason, the protrusions are formed so as to have a large size sufficient for this purpose. In other words, when protrusions where ink is held provide a high resistance, the effect of reducing the amount of satellite droplets and mist is enhanced. However, such protrusions cause an increase in the forward resistance, so that defective ejection tends to occur at the time of restarting of ejection.
Thus, while ejection orifices having protrusions are employed to reduce the amount of satellite droplets and mist to thereby improve printing quality, ejection stability needs to be improved at the time of restarting of ejection.
A liquid ejection head according to an embodiment of the subject disclosure includes a substrate; and an ejection orifice-forming member formed on the substrate and including an ejection orifice configured to eject liquid and a liquid channel communicating with the ejection orifice. The ejection orifice-forming member includes an ejection orifice-forming member layer A, an intermediate water-repellent layer, and an ejection orifice-forming member layer B in this order from a substrate-side of the member. The ejection orifice-forming member includes a protrusion protruding into the ejection orifice. The ejection orifice-forming member includes a water-repellent projection portion that is at least a portion of the intermediate water-repellent layer and that projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B.
The liquid ejection head according to this embodiment includes, within the ejection orifice, a protrusion protruding into the ejection orifice, so that the protrusion holds liquid to thereby decrease the length of the tails of droplets at the time of ejection of droplets. This results in a reduction in the amount of satellite droplets and mist, to thereby improve printing quality. In addition, since the liquid ejection head according to this embodiment includes a water-repellent projection portion that is at least a portion of the intermediate water-repellent layer and that projects into the ejection orifice, the meniscus of the liquid can be positioned at the water-repellent projection portion within the ejection orifice. As a result, even in the presence of the protrusion, a decrease in the forward resistance within the ejection orifice can be achieved, so that, after termination of printing, ejection stability at the time of restarting of ejection of liquid can be improved. In addition, without decreasing the thickness of the ejection orifice-forming member, a decrease in the forward resistance within the ejection orifice can be achieved. As a result, the rigidity of the ejection orifice-forming member can be maintained.
Liquid Ejection Head
A liquid ejection head according to this embodiment includes a substrate; and an ejection orifice-forming member formed on the substrate and including an ejection orifice configured to eject liquid and a liquid channel communicating with the ejection orifice. The ejection orifice-forming member includes an ejection orifice-forming member layer A, an intermediate water-repellent layer, and an ejection orifice-forming member layer B in this order from a substrate-side of the member. The ejection orifice-forming member includes a protrusion protruding into the ejection orifice. The ejection orifice-forming member includes a water-repellent projection portion that is at least a portion of the intermediate water-repellent layer and that projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. The water-repellent projection portion is formed at least on an area of the inner wall of the ejection orifice, the area not being the surface of the protrusion.
The liquid ejection head according to this embodiment includes, within the ejection orifice, a protrusion protruding into the ejection orifice, so that the protrusion holds liquid to thereby decrease the length of the tails of droplets at the time of ejection of droplets. This results in a reduction in the amount of satellite droplets and mist, to thereby improve printing quality. In addition, since the liquid ejection head according to this embodiment includes a water-repellent projection portion that is formed at least on an area of the inner wall of the ejection orifice, the area not being the surface of the protrusion, that is at least an area of the intermediate water-repellent layer, and that projects into the ejection orifice, the meniscus of the liquid can be positioned at the water-repellent projection portion within the ejection orifice. As a result, even in the presence of the protrusion, a decrease in the forward resistance within the ejection orifice can be achieved, so that, after termination of printing, ejection stability at the time of restarting of ejection of liquid can be improved. In addition, without decreasing the thickness of the ejection orifice-forming member, a decrease in the forward resistance within the ejection orifice can be achieved. As a result, the rigidity of the ejection orifice-forming member can be maintained.
Hereinafter, this embodiment according to the disclosure will be described with reference to drawings. An example to which the disclosure is applicable will be described with reference to an inkjet recording head, which is one example of liquid ejection heads. However, the scope to which a liquid ejection head according to the disclosure is applicable is not limited to the inkjet recording head.
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In this embodiment, the protrusions 11 and the water-repellent projection portion 12 are formed within the ejection orifice. However, the protrusions 11 are protrusion portions that are not the same as and are different from the water-repellent projection portion 12. For example, the water-repellent projection portion 12 may be formed on the area (not the protrusions 11) of the inner wall of the ejection orifice 9, and may be further formed on the surfaces of the protrusions 11. For example, in FIGS. 2A to 2E, the water-repellent projection portion 12 is formed on the area (not the protrusions 11) of the inner wall of the ejection orifice 9.
Each protrusion 11 may be constituted by the intermediate water-repellent layer 7 and the ejection orifice-forming member layer B 8. Alternatively, the protrusion 11 may be constituted by the ejection orifice-forming member layer A 6 and the intermediate water-repellent layer 7. Alternatively, the protrusion 11 may be constituted by the ejection orifice-forming member layer A 6, the intermediate water-repellent layer 7, and the ejection orifice-forming member layer B 8. The length (in the depth direction of the ejection orifice 9) of the protrusion 11 is not particularly limited, and may be 4 to 30 μm.
A static contact angle θs of the water-repellent projection portion 12 for pure water, a static contact angle θA of the ejection orifice-forming member layer A 6 for pure water, and a static contact angle θB of the ejection orifice-forming member layer B 8 for pure water preferably satisfy θs>θA and θs>θB. This is because, when θs>θA and θs>θB are satisfied, the meniscus of the liquid is easily maintained at the position of the water-repellent projection portion 12. θs is preferably 10° or more larger than θA and θB, more preferably, 20° or more larger than θA and θB.
From the viewpoint of easily maintaining the meniscus of the liquid at the position of the water-repellent projection portion 12, θs preferably satisfies θs>70°, more preferably θs>80°, still more preferably θs>90°. The upper limit of θs is not particularly limited; however, for example, θs satisfies θs≤120°. The ranges of θA and θB are not particularly limited; for example, θA and θB can satisfy 5°≤θA≤70° and 10°≤θB≤70°. Incidentally, θs, θA, and θB are measured with a contact angle meter CA-X150 (trade name, manufactured by Kyowa Interface Science Co., Ltd.) by measuring the contact angle of a 10 μl pure water droplet.
The ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8 are required to have mechanical strength, resistance to liquid such as ink, and adhesion to underlying components, and also have resolution of photolithographic materials. In order to satisfy the conditions of these properties, at least one of the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8 can be formed of a cured product of a composition containing a cationically polymerizable resin having two or more epoxy groups, and a photoacid generating agent that generates acid upon absorption of light. When the cationically polymerizable resin having two or more epoxy groups is used, the resultant cured product has a three-dimensional cross-linking, so that the above-described properties tend to be provided. Examples of the cationically polymerizable resin having two or more epoxy groups include epoxy resins such as bisphenol epoxy resins, phenol-novolac epoxy resins, cresol-novolac epoxy resins, and polyfunctional epoxy resins having an oxycyclohexane skeleton. Examples of the corresponding commercially available products include “CELLOXIDE 2021” and “EHPE3150” (all are trade names, manufactured by Daicel Corporation); “157S70” and “jER1031S” (all are trade names, manufactured by Mitsubishi Chemical Corporation); and “EPICLON N-695”, “EPICLON N-865”, and “EPICLON HP-7200” (all are trade names, manufactured by DIC Corporation). These resins may be used alone or in combination of two or more thereof.
Examples of the photoacid generating agent include sulfonic acid compounds, diazomethane compounds, sulfonium salt compounds, iodonium salt compounds, and disulfone compounds. Examples of the corresponding commercially available products include “ADEKA OPTOMER SP-170”, “ADEKA OPTOMER SP-172”, and “ADEKA OPTOMER SP-150” (all are trade names, manufactured by ADEKA CORPORATION); “BBI-103” and “BBI-102” (all are trade names, manufactured by Midori Kagaku Co., Ltd.); “IBPF”, “IBCF”, “TS-01”, and “TS-91” (all are trade names, manufactured by SANWA Chemical Co., Ltd.); “CPI-210”, “CPI-300”, “CPI-410” and “CPI-410S” (all are trade names, manufactured by San-Apro Ltd.); and “Irgacure290” (trade name, manufactured by BASF). These agents may be used alone or in combination of two or more thereof.
For the purpose of improving properties such as photolithographic performance and adhesion performance, the above-described composition may further contain a silane coupling agent; a photosensitizer such as an anthracene derivative; a basic substance such as an amine; and an acid generating agent that generates toluenesulfonic acid, which is weakly acidic (pKa=−1.5 to 3.0). Examples of commercially available products of the acid generating agent that generates toluenesulfonic acid include “TPS-1000” (trade name, manufactured by Midori Kagaku Co., Ltd.) and “WPAG-367” (trade name, manufactured by Wako Pure Chemical Industries, Ltd.). These agents may be used alone or in combination of two or more thereof. Examples of the above-described composition include commercially available negative resists such as “SU-8 series” (trade name, manufactured by Nippon Kayaku Co., Ltd.); and “TMMR S2000” and “TMMFS2000” (all are trade names, manufactured by TOKYO OHKA KOGYO CO., LTD.). Incidentally, in general, the cured product of the composition has a static contact angle for pure water of about 60°.
The intermediate water-repellent layer 7 can be formed of a cured product of a composition containing a condensate of a hydrolyzable silane compound having an epoxy group and a hydrolyzable silane compound having a perfluoropolyether group or a perfluoroalkyl group, a cationically polymerizable resin having two or more epoxy groups, and a photoacid generating agent that generates acid upon absorption of light. When such a composition containing a condensate of a hydrolyzable silane compound having a perfluoropolyether group or a perfluoroalkyl group is used, baking treatment causes such fluorine-containing groups to segregate at the interface between the composition and the air. As a result, the cured product tends to have a static contact angle for pure water of 70° or more, and θs>θA and θs>θB can be easily satisfied. Examples of the hydrolyzable silane compound having an epoxy group include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. These compounds may be used alone or in combination of two or more thereof. Examples of the hydrolyzable silane compound having a perfluoropolyether group include compounds represented by the following Formulas (1) to (4).
In Formula (1) above, g is 1 to 30. In Formula (2) above, Rm represents a methyl group or a hydrogen atom; and h is 1 to 30. In Formula (3) above, i is 1 to 30, and j is 1 to 4. In Formula (4) above, k is 1 to 30. These compounds may be used alone or in combination of two or more thereof. The cationically polymerizable resin having two or more epoxy groups and the photoacid generating agent may be the same compounds as in the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8.
In the inkjet recording head according to this embodiment, as illustrated in
The channel 4 is not particularly limited in terms of height; however, the height can be 3 to 20 μm. The ejection orifice-forming member layer A 6 over the channel 4 may have a thickness h that is preferably ⅔ or less of, more preferably ⅓ or less of the thickness H of the ejection orifice-forming member 5 over the channel 4. The intermediate water-repellent layer 7 preferably has a thickness of 0.3 μm or more, more preferably 1 to 3 μm. The ejection orifice-forming member layer B 8 on the intermediate water-repellent layer 7 is not particularly limited in terms of thickness; however, the thickness can be 2 μm or more. The ejection orifice-forming member 5 over the channel 4 is not particularly limited in terms of thickness H; however, the thickness H can be 4 to 30 μm. When the ejection orifice 9 has a circular shape, the larger diameter Φ1 is not particularly limited and can be 10 to 30 μm. The shorter diameter Φ2 is not particularly limited and can be 10 to 30 μm. The width x of the protrusion 11 is not particularly limited, and can be 1.5 to 5 μm. The length y of the protrusion 11 is not particularly limited, and can be ⅙ or more of the shorter diameter Φ2. When plural protrusions 11 are formed, the gap width a of the protrusions 11 is not particularly limited, and can be 1 to 15 μm. The projection length d of the water-repellent projection portion 12 is preferably 0.1 to 3 μm, more preferably 0.5 to 1.5 μm.
Method for Producing Liquid Ejection Head
Some examples of a method for producing a liquid ejection head according to this embodiment, the following first to third production methods, will be described. Incidentally, inkjet recording heads, which are examples of liquid ejection heads, will be described as examples to which the disclosure is applicable. However, the scope to which a method for producing a liquid ejection head according to the disclosure is applicable is not limited to inkjet recording heads.
(1) First Production Method
A method for producing a liquid ejection head according to this embodiment includes a step of forming, on a substrate, a shape member used for forming a liquid channel and formed of a channel-forming resin composition; a step of forming, on the shape member and the substrate, a layer that is formed of a photosensitive resin composition A and that is curable into an ejection orifice-forming member layer A; a step of forming, on the layer formed of the photosensitive resin composition A, a layer that is formed of a photosensitive resin composition C and that is curable into an intermediate water-repellent layer; a step of forming, on the layer formed of the photosensitive resin composition C, a layer that is formed of a photosensitive resin composition B and that is curable into an ejection orifice-forming member layer B; a step of exposing the layer formed of the photosensitive resin composition A, the layer formed of the photosensitive resin composition C, and the layer formed of the photosensitive resin composition B, to form a pattern of an ejection orifice for ejecting liquid, a protrusion protruding into the ejection orifice, and a water-repellent projection portion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition A, the layer formed of the photosensitive resin composition C, and the layer formed of the photosensitive resin composition B; and a step of removing the shape member. The water-repellent projection portion is at least a portion of the intermediate water-repellent layer, and projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. According to this method, the liquid ejection head according to this embodiment can be efficiently produced with high accuracy.
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The method according to this embodiment can further include a step of performing heating at 90° C. or more and 250° C. or less after the step of removing the unexposed regions from the layer 14 formed of the photosensitive resin composition A, the layer 15 formed of the photosensitive resin composition C, the layer 16 formed of the photosensitive resin composition B, and optionally the layer 17 formed of the photosensitive resin composition D. The heating temperature is more preferably 120° C. or more and 240° C. or less, still more preferably 150° C. or more and 220° C. or less. When the heating temperature is 90° C. or more, the fluorine-containing groups of the water-repellent projection portion 12 can be made to sufficiently segregate at the interface between the water-repellent projection portion 12 and the air, to thereby sufficiently decrease the surface energy, compared with the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8. As a result, the meniscus of the liquid can be easily maintained at the position of the water-repellent projection portion 12. In addition, when the heating temperature is 250° C. or less, degradation of the durability of the ejection orifice-forming member due to decomposition of the resin can be sufficiently prevented. Incidentally, the heating step may be performed after the step of removing the shape member 13.
After that, electrical connections are established, and an ink supply unit is appropriately disposed to thereby provide an inkjet recording head.
(2) Second Production Method
A method for producing a liquid ejection head according to this embodiment includes a step of forming, on a substrate, a shape member used for forming a liquid channel and formed of a channel-forming resin composition; a step of forming, on the shape member and the substrate, a layer that is formed of a photosensitive resin composition A and that is curable into an ejection orifice-forming member layer A; a step of exposing the layer formed of the photosensitive resin composition A, to form a pattern of an ejection orifice for ejecting liquid; a step of forming, on the layer formed of the photosensitive resin composition A, a layer that is formed of a photosensitive resin composition C and that is curable into an intermediate water-repellent layer; a step of exposing the layer formed of the photosensitive resin composition C to form a pattern of the ejection orifice, a protrusion protruding into the ejection orifice, and a water-repellent projection portion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition A and the layer formed of the photosensitive resin composition C; a step of forming, on the intermediate water-repellent layer, a layer that is formed of a photosensitive resin composition B and that is curable into an ejection orifice-forming member layer B; a step of exposing the layer formed of the photosensitive resin composition B, to form a pattern of the ejection orifice and the protrusion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition B; and a step of removing the shape member. The water-repellent projection portion is at least a portion of the intermediate water-repellent layer, and projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. According to this method, the liquid ejection head according to this embodiment can be efficiently produced with high accuracy.
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As in the first embodiment, the method according to this embodiment can further include a step of performing heating at 90° C. or more and 250° C. or less after the step of removing the unexposed regions from the layer 16 formed of the photosensitive resin composition B. Incidentally, the heating step may be performed after the step of removing the shape member 13.
After that, electrical connections are established, and an ink supply unit is appropriately disposed to thereby provide an inkjet recording head.
(3) Third Production Method
A method for producing a liquid ejection head according to this embodiment includes a step of forming, on a substrate, a layer that is formed of a photosensitive resin composition E and that is curable into a channel-forming member; a step of forming, on the layer formed of the photosensitive resin composition E, a layer that is formed of a photosensitive resin composition A and that is curable into an ejection orifice-forming member layer A; a step of exposing the layer formed of the photosensitive resin composition E, to form a pattern of a liquid channel; a step of exposing the layer formed of the photosensitive resin composition A, to form a pattern of an ejection orifice for ejecting liquid; a step of removing unexposed regions from the layer formed of the photosensitive resin composition E and the layer formed of the photosensitive resin composition A; a step of forming, in the following order, on the ejection orifice-forming member layer A, a layer that is formed of a photosensitive resin composition C and that is curable into an intermediate water-repellent layer, and a layer that is formed of a photosensitive resin composition B and that is curable into an ejection orifice-forming member layer B; a step of exposing the layer formed of the photosensitive resin composition C and the layer formed of the photosensitive resin composition B, to form a pattern of the ejection orifice, a protrusion that protrudes into the ejection orifice, and a water-repellent projection portion; and a step of removing unexposed regions from the layer formed of the photosensitive resin composition C and the layer formed of the photosensitive resin composition B. The water-repellent projection portion is at least a portion of the intermediate water-repellent layer, and projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. According to this method, the liquid ejection head according to this embodiment can be efficiently produced with high accuracy.
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As in the first embodiment, the method according to this embodiment can further include a step of performing heating at 90° C. or more and 250° C. or less after the step of removing the unexposed regions from the layer formed of the photosensitive resin composition C and the layer formed of the photosensitive resin composition B.
After that, electrical connections are established, and an ink supply unit is appropriately disposed to thereby provide an inkjet recording head.
Liquid Ejection Head
A liquid ejection head according to the second embodiment includes a substrate; and an ejection orifice-forming member formed on the substrate and including an ejection orifice configured to eject liquid and a liquid channel communicating with the ejection orifice. The ejection orifice-forming member includes an ejection orifice-forming member layer A, an intermediate water-repellent layer, and an ejection orifice-forming member layer B in this order from a substrate-side of the member. The ejection orifice-forming member includes a protrusion protruding into the ejection orifice. The ejection orifice-forming member includes a water-repellent projection portion that is a portion of the intermediate water-repellent layer, the portion being on the surface of the tip of the protrusion, and that projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. The water-repellent projection portion is formed at least on a portion of the inner wall of the ejection orifice, the portion being the surface of the tip of the protrusion.
The liquid ejection head according to this embodiment includes, within the ejection orifice, a protrusion protruding into the ejection orifice, so that the protrusion holds liquid to thereby decrease the length of the tails of droplets at the time of ejection of droplets. This results in a reduction in the amount of satellite droplets and mist, to thereby improve printing quality. In addition, the liquid ejection head according to this embodiment includes, on the surface of the tip of the protrusion, a water-repellent projection portion, which is a portion of the intermediate water-repellent layer, the portion projecting into the ejection orifice, so that a liquid film formed on the protrusion is divided at an earlier timing and between the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. As a result, even with an increase in the protrusion gap width for the purpose of decreasing the forward resistance, the amount of satellite droplets and mist can be sufficiently decreased. Thus, the amount of satellite droplets and mist can be decreased to improve printing quality, and ejection stability at the time of restarting of ejection of liquid can be improved.
Hereinafter, this embodiment according to the disclosure will be described with reference to drawings. An example to which the disclosure is applicable will be described with an inkjet recording head, which is one of liquid ejection heads. However, the scope to which a liquid ejection head according to the disclosure is applicable is not limited to the inkjet recording head. In the following description, features different from those of the first embodiment will be mainly described, and redundant descriptions of some features having been described in the first embodiment are omitted.
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Each protrusion 11 may be constituted by the intermediate water-repellent layer 7 and the ejection orifice-forming member layer B 8. Alternatively, the protrusion 11 may be constituted by the ejection orifice-forming member layer A 6 and the intermediate water-repellent layer 7. Alternatively, the protrusion 11 may be constituted by the ejection orifice-forming member layer A 6, the intermediate water-repellent layer 7, and the ejection orifice-forming member layer B 8. The length (in the depth direction of the ejection orifice 9) of the protrusion 11 is not particularly limited, and may be 6 to 50 μm.
A static contact angle θs of the water-repellent projection portion 12 for pure water, a static contact angle θA of the ejection orifice-forming member layer A 6 for pure water, and a static contact angle θB of the ejection orifice-forming member layer B 8 for pure water preferably satisfy θs>θA and θs>θB. When θs>θA and θs>θB are satisfied, the liquid film having been turned from a liquid column and at the water-repellent projection portion 12, is divided at an earlier timing and between the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8, hence breakage of the liquid column occurs at an earlier timing. Thus, even with an increased gap width a between the protrusions 11 for the purpose of decreasing the forward resistance, the amount of satellite droplets and mist is sufficiently decreased. This is because the meniscus of the liquid is easily maintained at the position of the water-repellent projection portion 12. θs is preferably 10° or more larger than θA and θB, more preferably, 20° or more larger than θA and θB.
θs>70° is preferably satisfied from the viewpoint that the liquid film having been turned from a liquid column and at the water-repellent projection portion 12, is divided at an earlier timing and between the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8, hence breakage of the liquid column occurs at an earlier timing. θs more preferably satisfies θs>80°, still more preferably θs>90°. The upper limit of θs is not particularly limited; however, for example, θs satisfies θs≤120°. The ranges of θA and θB are not particularly limited; for example, θA and θB can satisfy 50°≤θA≤70° and 10°≤θB≤70°. Incidentally, θs, θA, and θB are measured with a contact angle meter CA-X150 (trade name, manufactured by Kyowa Interface Science Co., Ltd.) by measuring the contact angle of a 10 μl pure water droplet.
The channel 4 is not particularly limited in terms of height; however, the height can be 3 to 20 μm. The ejection orifice-forming member layer A 6 over the channel 4 may have a thickness h that is ⅙ or more of the thickness H of the ejection orifice-forming member 5 over the channel 4. The intermediate water-repellent layer 7 preferably has a thickness of 0.3 μm or more, more preferably 1 to 3 μm. The ejection orifice-forming member layer B 8 on the intermediate water-repellent layer 7 is not particularly limited in terms of thickness; however, the thickness can be ⅙ or more of the thickness H of the ejection orifice-forming member 5 over the channel 4. The ejection orifice-forming member 5 over the channel 4 is not particularly limited in terms of thickness H; however, the thickness H can be 6 to 50 μm. When the ejection orifice 9 has a circular shape, the larger diameter Φ1 is not particularly limited and can be 10 to 30 μm. The shorter diameter Φ2 is not particularly limited and can be 10 to 30 μm. The width x of the protrusion 11 is not particularly limited, and can be 1.5 to 5 μm. The length y of the protrusion 11 is not particularly limited, and can be ⅙ or more of the shorter diameter Φ2. When plural protrusions 11 are formed, the gap width a of the protrusions 11 is not particularly limited, and can be 1 to 15 μm. The projection length d of the water-repellent projection portion 12 is preferably 0.1 to 3 μm, more preferably 0.5 to 1.5 μm.
Method for Producing Liquid Ejection Head
Some examples of a method for producing a liquid ejection head according to the second embodiment, the following fourth and fifth production methods, will be described. Incidentally, inkjet recording heads, which are examples of liquid ejection heads, will be described as examples to which the disclosure is applicable. However, the scope to which a method for producing a liquid ejection head according to the disclosure is applicable is not limited to inkjet recording heads.
(4) Fourth Production Method
A method for producing a liquid ejection head according to this embodiment includes a step of forming, on a substrate, a shape member used for forming a liquid channel and formed of a channel-forming resin composition; a step of forming, on the shape member and the substrate, a layer that is formed of a photosensitive resin composition A and that is curable into an ejection orifice-forming member layer A; a step of forming, on the layer formed of the photosensitive resin composition A, a layer that is formed of a photosensitive resin composition C and that is curable into an intermediate water-repellent layer; a step of forming, on the layer formed of the photosensitive resin composition C, a layer that is formed of a photosensitive resin composition B and that is curable into an ejection orifice-forming member layer B; a step of exposing the layer formed of the photosensitive resin composition A, the layer formed of the photosensitive resin composition C, and the layer formed of the photosensitive resin composition B, to form a pattern of an ejection orifice for ejecting liquid, a protrusion protruding into the ejection orifice, and a water-repellent projection portion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition A, the layer formed of the photosensitive resin composition C, and the layer formed of the photosensitive resin composition B; and a step of removing the shape member. The water-repellent projection portion is a portion of the intermediate water-repellent layer on the tip of the protrusion, and projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. According to this method, the liquid ejection head according to this embodiment can be efficiently produced with high accuracy.
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The method according to this embodiment can further include a step of performing heating at 90° C. or more and 250° C. or less after the step of removing the unexposed regions from the layer 14 formed of the photosensitive resin composition A, the layer 15 formed of the photosensitive resin composition C, the layer 16 formed of the photosensitive resin composition B, and optionally the layer 17 formed of the photosensitive resin composition D. The heating temperature is more preferably 120° C. or more and 240° C. or less, still more preferably 150° C. or more and 220° C. or less. When the heating temperature is 90° C. or more, the fluorine-containing groups of the water-repellent projection portion 12 can be made to sufficiently segregate at the interface between the water-repellent projection portion 12 and the air, to thereby sufficiently decrease the surface energy, compared with the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8. As a result, the liquid film having been turned from a liquid column and at the water-repellent projection portions 12, is divided at an earlier timing and between the ejection orifice-forming member layer A 6 and the ejection orifice-forming member layer B 8, hence breakage of the liquid column occurs at an earlier timing. In addition, when the heating temperature is 250° C. or less, degradation of the durability of the ejection orifice-forming member due to decomposition of the resin can be sufficiently prevented. Incidentally, the heating step may be performed after the step of removing the shape member 13.
After that, electrical connections are established, and an ink supply unit is appropriately disposed to thereby provide an inkjet recording head.
(5) Fifth Production Method
A method for producing a liquid ejection head according to this embodiment includes a step of forming, on a substrate, a shape member used for forming a liquid channel and formed of a channel-forming resin composition; a step of forming, on the shape member and the substrate, a layer that is formed of a photosensitive resin composition A and that is curable into an ejection orifice-forming member layer A; a step of exposing the layer formed of the photosensitive resin composition A, to form a pattern of an ejection orifice for ejecting liquid and a protrusion protruding into the ejection orifice; a step of forming, on the layer formed of the photosensitive resin composition A, a layer that is formed of a photosensitive resin composition C and that is curable into an intermediate water-repellent layer; a step of exposing the layer formed of the photosensitive resin composition C, to form a pattern of the ejection orifice, the protrusion, and a water-repellent projection portion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition A and the layer formed of the photosensitive resin composition C; a step of forming, on the intermediate water-repellent layer, a layer that is formed of a photosensitive resin composition B and that is curable into an ejection orifice-forming member layer B; a step of exposing the layer formed of the photosensitive resin composition B, to form a pattern of the ejection orifice and the protrusion; a step of removing unexposed regions from the layer formed of the photosensitive resin composition B; and a step of removing the shape member. The water-repellent projection portion is a portion of the intermediate water-repellent layer on the tip of the protrusion, and projects farther into the ejection orifice than the ejection orifice-forming member layer A and the ejection orifice-forming member layer B. According to this method, the liquid ejection head according to this embodiment can be efficiently produced with high accuracy.
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As in the first embodiment, the method according to this embodiment can further include a step of performing heating at 90° C. or more and 250° C. or less after the step of removing the unexposed regions from the layer 16 formed of the photosensitive resin composition B. Incidentally, the heating step may be performed after the step of removing the shape member 13.
After that, electrical connections are established, and an ink supply unit is appropriately disposed to thereby provide an inkjet recording head.
In this Example, the steps illustrated in
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Incidentally, in Table 2, the silane condensate was prepared in the following manner. To a flask equipped with a condenser, the following compounds were added: 12.53 g (0.045 mol) of γ-glycidoxypropyltriethoxysilane, 8.02 g (0.0225 mol) of methyltriethoxysilane, 4.46 g (0.0225 mol) of phenyltrimethoxysilane, 0.96 g (0.726 mmol) of a compound represented by Formula (1) above, 5.93 g of water, 15.15 g of ethanol, and 3.83 g of hydrofluoroether (trade name: HFE7200, manufactured by Sumitomo 3M Limited). These compounds were stirred at room temperature for 5 minutes, and then heated to reflux for 24 hours. Thus, the silane condensate was prepared.
The photosensitive resin composition described in Table 1 was used to form a film on a silicon substrate. The film was exposed at 10000 J/m2, and heat treatment was performed at 90° C. for 5 minutes. The resultant cured product was found to have a static contact angle for pure water (θA, θB) of 59°. The photosensitive resin composition described in Table 2 was used to form a film on a silicon substrate. The film was exposed at 1000 J/m2, and heat treatment was performed at 90° C. for 5 minutes. The resultant cured product was found to have a static contact angle for pure water (θs) of 98°. Incidentally, the static contact angles were measured with a contact angle meter CA-X150 (trade name, manufactured by Kyowa Interface Science Co., Ltd.) and as contact angles for a 10 μl pure water droplet.
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Incidentally, the photosensitive resin composition described in Table 3 was used to form a film on a silicon substrate, and the film was exposed at 4000 J/m2 and subjected to heat treatment at 90° C. for 5 minutes. The resultant cured product was found to have a static contact angle for pure water (θB) of 60°.
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An inkjet recording head was produced as in Example 1 except that the pattern of the water-repellent projection portion pattern mask 19 was changed such that the water-repellent projection portions 12 had a projection length d of 0.5 μm. The dimensions of components of the obtained inkjet recording head are described in Table 5.
An inkjet recording head was produced as in Example 1 except that the thickness of the layer 14 formed of the photosensitive resin composition A was changed to 20 μm, the thickness of the layer 16 formed of the photosensitive resin composition B was changed to 4 μm, and the thickness h of the ejection orifice-forming member layer A 6 over the channel 4 was changed to 5 μm. The dimensions of components of the obtained inkjet recording head are described in Table 5.
In this Comparative Example, the steps illustrated in
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An inkjet recording head was produced as in Comparative Example 1 except that the thickness of the layer 14 formed of the photosensitive resin composition A was changed to 18 μm. The dimensions of components of the obtained inkjet recording head are described in Table 5.
An inkjet recording head was produced as in Comparative Example 1 except that, in the step illustrated in
Evaluations
An ink having a viscosity of 2.4 cps and a surface tension of 33 dyn/cm was charged into each of the inkjet recording heads produced in Examples 1 to 5 and Comparative Examples 1 to 3, and these inkjet recording heads were evaluated in the following manner.
Evaluation for Post-Termination Printing
Printing was terminated for a printing termination period of 0.9 seconds or 2.7 seconds, and then printing was performed again and evaluated as to whether or not the ink was normally ejected, on the basis of the following evaluation grades. The results are summarized in Table 6.
Good: Ink is normally ejected even after the printing termination period.
Poor: Ink cannot be normally ejected after the printing termination period.
Evaluation for Printing for 1000 Sheets
The printing quality after printing for 1000 sheets was evaluated on the basis of the following evaluation grades. The results are summarized in Table 6.
Good: the amount of satellite droplets generated is small, and the degree of misdirection of ink droplets is low, so that the image quality is not adversely affected.
Poor: in addition to main ink droplets, satellite droplets are generated and degrade the image quality.
Very poor: misfiring of ink droplets or misdirection of ink droplets occurs and considerably degrades the image quality.
As shown in Table 6, in the evaluation for post-termination printing, the inkjet recording heads of Examples 1 to 5 were evaluated as performing normal ejection of ink even after the printing termination period. In addition, the inkjet recording heads of Examples 1 to 5 were evaluated as providing high printing quality even after printing for 1000 sheets. On the other hand, in the inkjet recording head of Comparative Example 1, after a printing termination period of 2.7 seconds, misfiring of the ink occurred, or the ink was not normally ejected and misdirected. In the inkjet recording head of Comparative Example 2, in the evaluation for printing for 1000 sheets, the initial printing quality was good; however, the printing quality was gradually degraded. After the printing for 1000 sheets, observation of the ejection orifice-forming member of the inkjet recording head of Comparative Example 2 revealed cracking at several sites. This was probably caused because the ejection orifice-forming member was thin and had low rigidity, and the force applied by wiping caused the cracking. In the inkjet recording head of Comparative Example 3, after the printing for 1000 sheets, misdirection occurred for main droplets and satellite droplets.
In this Example, the steps illustrated in
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Incidentally, in Table 8, the silane condensate was prepared in the following manner. To a flask equipped with a condenser, the following compounds were added: 12.53 g (0.045 mol) of γ-glycidoxypropyltriethoxysilane, 8.02 g (0.0225 mol) of methyltriethoxysilane, 4.46 g (0.0225 mol) of phenyltrimethoxysilane, 0.96 g (0.726 mmol) of a compound represented by Formula (1) above, 5.93 g of water, 15.15 g of ethanol, and 3.83 g of hydrofluoroether (trade name: HFE7200, manufactured by Sumitomo 3M Limited). These compounds were stirred at room temperature for 5 minutes, and then heated to reflux for 24 hours. Thus, the silane condensate was prepared.
The photosensitive resin composition described in Table 7 was used to form a film on a silicon substrate. The film was exposed at 10000 J/m2, and heat treatment was performed at 90° C. for 5 minutes. The resultant cured product was found to have a static contact angle for pure water (θA, θB) of 59°. The photosensitive resin composition described in Table 8 was used to form a film on a silicon substrate. The film was exposed at 1000 J/m2, and heat treatment was performed at 90° C. for 5 minutes. The resultant cured product was found to have a static contact angle for pure water (θs) of 98°. Incidentally, the static contact angles were measured with a contact angle meter CA-X150 (trade name, manufactured by Kyowa Interface Science Co., Ltd.) and as contact angles for a 10 μl pure water droplet.
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Incidentally, the photosensitive resin composition described in Table 9 was used to form a film on a silicon substrate, and the film was exposed at 4000 J/m2 and subjected to heat treatment at 90° C. for 5 minutes. The resultant cured product was found to have a static contact angle for pure water (θB) of 60°.
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An inkjet recording head was produced as in Example 6 except that the pattern of the water-repellent projection portion pattern mask 19 was changed such that the water-repellent projection portions 12 had a projection length d of 1.0 μm. The dimensions of components of the obtained inkjet recording head are described in Table 10.
An inkjet recording head was produced as in Example 6 except that the pattern of the water-repellent projection portion pattern mask 19 was changed such that the water-repellent projection portions 12 had a projection length d of 1.5 μm. The dimensions of components of the obtained inkjet recording head are described in Table 10.
An inkjet recording head was produced as in Comparative Example 1 except that the thickness of the layer 14 formed of the photosensitive resin composition A was changed to 26 μm, and the length y of the protrusions 11 was changed to 3.3 μm. The dimensions of components of the obtained inkjet recording head are described in Table 10.
An inkjet recording head was produced as in Comparative Example 4 except that the length y of the protrusions 11 was changed to 3.9 μm. The dimensions of components of the obtained inkjet recording head are described in Table 10.
Evaluations
An ink having a viscosity of 2.4 cps and a surface tension of 33 dyn/cm was charged into each of the inkjet recording heads produced in Examples 6 to 9 and Comparative Examples 4 and 5, and these inkjet recording heads were evaluated in the following manner.
Evaluation for Post-Termination Printing
Printing was terminated for a printing termination period of 0.9 seconds, 1.8 seconds, or 2.7 seconds, and then printing was performed again and evaluated as to whether or not the ink was normally ejected, on the basis of the following evaluation grades. The results are summarized in Table 11.
Good: Ink is normally ejected even after the printing termination period.
Poor: Ink cannot be normally ejected after the printing termination period.
Evaluation for Printing for 1000 Sheets
The printing quality after printing for 1000 sheets was evaluated on the basis of the following evaluation grades. The results are summarized in Table 11.
Good: the image quality is good even after printing for 1000 sheets.
As shown in Table 11, in the evaluation for post-termination printing, the inkjet recording heads of Examples 6 to 9 were evaluated as performing normal ejection of ink even after the printing termination period. In addition, the inkjet recording heads of Examples 6 to 9 were evaluated as providing high printing quality even after printing for 1000 sheets. On the other hand, in the inkjet recording heads of Comparative Examples 4 and 5, after a printing termination period of 2.7 seconds in Comparative Example 4 and after a printing termination period of 1.8 seconds in Comparative Example 5, misfiring of the ink occurred, or the ink was not normally ejected and misdirected.
While the disclosure has been described with reference to example embodiments, it is to be understood that the invention is not limited to the disclosed example embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2016-189754 filed Sep. 28, 2016, and No. 2016-189755 filed Sep. 28, 2016, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-189754 | Sep 2016 | JP | national |
| 2016-189755 | Sep 2016 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8551351 | Nakamoto | Oct 2013 | B2 |
| Number | Date | Country |
|---|---|---|
| 2007518587 | Jul 2007 | JP |
| 2011207235 | Oct 2011 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20180086080 A1 | Mar 2018 | US |
