Patent Application
20160091789
1. Field of the Invention
The present invention relates to a production process for an optically shaped product and a production process for a liquid discharge head using this production process.
2. Description of the Related Art
As an example of an optically shaped product, a liquid discharge head discharging a liquid may be mentioned. The liquid discharge head is used for discharging an ink in an ink jet recording apparatus as, for example, an ink jet recording head. The liquid discharge head applied to the ink jet recording generally includes plural fine discharge ports, flow paths respectively communicating with the discharge ports and discharge energy generating elements each provided at a part of the flow path for generating energy for discharging a liquid within the flow path. As a production process for such a liquid discharge head, a process of laminating a low-sensitive photosensitive resin layer forming a flow path and a high-sensitive photosensitive resin layer which will become a discharge port by patterning on a substrate in which a discharge energy generating element has been provided in advance is known. The low-sensitive photosensitive resin layer and the high-sensitive photosensitive resin layer are respectively cured, and uncured portions thereof are then removed, thereby forming the flow path and the discharge port on the substrate.
In the production process for an ink jet recording head disclosed in Japanese Patent Application Laid-Open No. 2009-1003, a film of a low-sensitive photosensitive resin which is liquid is first formed on a substrate by a spin-coating method, and the film is exposed to be in a form of a flow path. After a dry film of a high-sensitive photosensitive resin is then laminated on the resultant low-sensitive photosensitive resin layer and exposed to be in a form of a discharge port, uncured portions of the low-sensitive photosensitive resin layer and the high-sensitive photosensitive resin layer are collectively removed to form the flow path and the discharge port. Thereafter, the substrate is etched from a surface on which none of the photosensitive resin layers was laminated to form a supply path for supplying a liquid to the flow path passing through the substrate.
According to the present invention, there is provided a production process for an optically shaped product, which comprises applying a photosensitive resin composition in a form of a dry film on to a substrate in which a hole opening to a surface thereof is formed so as to cover the hole and performing patterning to form an optically shaped product, wherein the photosensitive resin composition contains a resin comprising a tri- or higher functional epoxy resin and a bifunctional epoxy resin, the bifunctional epoxy resin has a weight-average molecular weight (Mw) of 5,500 to 60,000, the resin has a weight-average molecular weight (Mw) ranging from 4,500 to 11,000, and a mixing ratio by mass between the tri- or higher functional epoxy resin and the bifunctional epoxy resin satisfies (b)/(a)≦1.5, where (a) is a mass of the tri- or higher functional epoxy resin, and (b) is a mass of the bifunctional epoxy resin.
According to the present invention, there is also provided a production process for a liquid discharge head, which comprises applying a photosensitive resin composition in a form of a dry film on to a substrate in which a discharge energy generating element and a liquid supply path for liquid are formed, wherein the photosensitive resin composition contains a resin comprising a tri- or higher functional epoxy resin and a bifunctional epoxy resin, the bifunctional epoxy resin has a weight-average molecular weight (Mw) of 5,500 to 60,000, the resin has a weight-average molecular weight (Mw) ranging from 4,500 to 11,000, and a mixing ratio by mass between the tri- or higher functional epoxy resin and the bifunctional epoxy resin satisfies (b)/(a)≦1.5, where (a) is a mass of the tri- or higher functional epoxy resin, and (b) is a mass of the bifunctional epoxy resin.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.
In the production process for the ink jet recording head described in Japanese Patent Application Laid-Open No. 2009-1003, a low-sensitive photosensitive resin layer is formed on a substrate by a spin-coating method, so that the formation of a supply path is conducted only after the formation of the low-sensitive photosensitive resin layer. In addition, etching for forming the supply path in the substrate can be conducted only from the surface on which no photosensitive resin layer is formed, so that the step for forming the supply path is highly restricted. On the other hand, in order to form the low-sensitive photosensitive resin layer on a substrate in which a supply path which is a through-hole is formed in advance, there is a method of forming a dry film of a low-sensitive photosensitive resin and then transferring this dry film on to the substrate. According to this method, however, both dry films of the low-sensitive photosensitive resin and a high-sensitive photosensitive resin fall in the interior of the supply path at the opening of the supply path when the dry film of the high-sensitive photosensitive resin is further transferred, and so the heights of the respective photosensitive resin layers after curing may become uneven in some cases. When such height unevenness occurs, a flow path height and a discharge port height become uneven, so that discharge accuracy in the ink jet recording head produced is lowered. Here, the discharge port height means a distance from the surface of the substrate to a position of the discharge port. The problem in the production process for the ink jet recording head has been described here. However, this problem is common to a production process for an optically shaped product by transferring a photosensitive resin layer which is a dry film on to a substrate in which an opening or a recessed portion is provided in advance.
It is an object of the present invention to provide a production process for an optically shaped product, by which falling-in of a photosensitive resin layer into a recessed portion or a through-hole is small upon the formation of the optically shaped product by using a substrate having the recessed portion or the through-hole, and the height of the photosensitive resin layer after curing is controlled.
Another object of the present invention is to provide a production process for a liquid discharge head by laminating a photosensitive resin layer on a substrate in which a supply path is formed in advance, by which falling-in of the photosensitive resin layer into the supply path is small, and a flow path height and a discharge port height can be made even.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. A case where a production process for an optically shaped product based on the present invention is applied to the production of a liquid discharge head will hereinafter be described as an example. However, the production process for the optically shaped product according to the present invention is not limited to the application to the production of the liquid discharge head.
A production process for the liquid discharge head illustrated in
After the photosensitive resin composition (1) is first applied on to a film substrate composed of polyethylene terephthalate (PET) or polyimide, the photosensitive resin composition (1) is transferred on to a substrate 2 in which a discharge energy generating element is arranged by means of a laminating method, thereby forming a film. A first photosensitive resin composition layer 10 composed of an uncured photosensitive resin composition (1) is thereby formed on the substrate 2 as illustrated in
The first photosensitive resin composition layer is then subjected to pattern exposure through a flow path forming mask 11 having a flow path pattern, and the exposed portion is cured by additionally conducting a heat treatment (post exposure bake) to form a flow path forming member 4 as illustrated in
The photosensitive resin composition (2) is then applied on to a film substrate composed of PET or polyimide to form a film. Thereafter, the photosensitive resin composition (2) is transferred in a form of a dry film on to the first photosensitive resin composition layer 10 and the flow path forming member 4 by means of a laminating method to form a second photosensitive resin composition layer 12. Accordingly, the photosensitive resin composition (2) is laminated in a form of a dry film on the photosensitive resin composition (1). A water-repellent layer 9 is additionally formed on the second photosensitive resin composition layer 12 as needed as illustrated in
The water-repellent layer 9 is required to have repellency with respect to a liquid discharged from the liquid discharge head. A perfluoroalkyl composition or perfluoropolyether composition having cationic polymerizability is suitably used as the water-repellent layer 9. The perfluoroalkyl composition or perfluoropolyether composition is generally known to segregate a fluorinated alkyl chain at an interface between the composition and air by a bake treatment after the application thereof. The water-repellency of the surface of the composition can be enhanced by this segregated fluorinated alkyl chain.
The second photosensitive resin composition layer 12 and the water-repellent layer 9 are then subjected to pattern exposure through a discharge port forming mask 13 having a discharge port pattern, and the exposed portion is cured by additionally conducting a heat treatment (post exposure bake) to form a discharge port forming member 8 as illustrated in
The discharge port forming mask 13 is obtained by forming a light shielding film 13A such as a chromium film according to a pattern such as a discharge port on a substrate composed of a material such as glass or quartz transmitting light of an exposure wavelength. The same apparatus as that used in the exposure of the first photosensitive resin composition layer 10 may be used as an exposure apparatus. In addition, the discharge port pattern, i.e. the plane shape of the discharge port, may not always be circular and may be suitably determined in view of, for example, discharge characteristics, including the shapes illustrated in
Unexposed portions of the first photosensitive resin composition layer 10, the second photosensitive resin composition layer 12 and the water-repellent layer 9 are collectively removed with an organic solvent to form a flow path 5 and a discharge port 6 as illustrated in
In the production process for the liquid discharge head as described above, the second photosensitive resin composition layer 12 is laminated after the first photosensitive resin composition layer 10 is exposed. However, the second photosensitive resin composition layer 12 may be laminated before the first photosensitive resin composition layer 10 is exposed. Production steps in the case where the second photosensitive resin composition layer 12 is laminated before the first photosensitive resin composition layer 10 is exposed will now be described.
After the same photosensitive resin composition (1) as that described above is first applied on to a film substrate composed of PET or polyimide, the photosensitive resin composition (1) is transferred on to a substrate 2 in which a discharge energy generating element 1 is arranged by means of a laminating method, thereby forming a film. A supply path 3 forming a hole opening to surfaces of the substrate 2 is provided in the substrate 2, and this hole is covered with the first photosensitive resin composition (1). A first photosensitive resin composition layer 10 composed of an uncured photosensitive resin composition (1) is thereby formed on the substrate 2 as illustrated in
The first photosensitive resin composition layer 10 and the second photosensitive resin composition layer 12 are then subjected to pattern exposure through a flow path forming mask 11 having a flow path pattern, and a heat treatment is additionally conducted to cure exposed portions. As a result, as illustrated in
Uncured portions of the first photosensitive resin composition layer 10, the second photosensitive resin composition layer 12 and the water-repellent layer 9 are collectively removed with an organic solvent to form a flow path 5 and a discharge port 6 as illustrated in
Even in the production process illustrated in
The respective photosensitive resin compositions used in this embodiment will now be described.
The photosensitive resin composition (1) forming the first photosensitive resin composition layer 10 is a negative photosensitive epoxy resin composition containing a resin comprising a tri- or higher functional epoxy resin (a) and a bifunctional epoxy resin (b). In addition, this composition favorably contains a photoacid generator. A cured product of the photosensitive resin composition (1) is required to have mechanical strength and adhesion to a substrate. In addition, the photosensitive resin composition (1) needs to be selected in view of resolution as a photolithographic material. Since a layer formed of the photosensitive resin composition (1) is formed in a form of a dry film on a substrate having a recessed portion or through-hole which will become an opening at a surface, the photosensitive resin composition (1) requires to have such a film strength that the layer is not deformed even in an uncured state upon transfer or another heat step. This embodiment intends to obtain an optically shaped product in which the height of the photosensitive resin layer after curing is controlled by covering a hole with a photosensitive resin composition having such a film strength that the layer is not deformed even in an uncured state.
The photosensitive resin composition (1) contains a resin having a trivalent or higher polyvalent epoxy group as a trivalent or higher polyfunctional epoxy resin (a), whereby crosslinking is caused to three-dimensionally proceed to improve sensitivity as a photosensitive material. The tri- or higher functional epoxy resin (a) favorably has an epoxy equivalent less than 500 and a softening point of 60° C. or higher though no particular limitation is imposed on them. When the epoxy equivalent is 500 or higher, the sensitivity of the resulting resin composition becomes insufficient, so that the lowering of pattern resolution or the lowering of mechanical strength or adhesion of a cured product may be caused in some cases. In addition, when the softening point is less than 60° C., the photosensitive resin composition (1) applied on to the film substrate for forming a dry film may be softened in a production apparatus in some cases, which forms the cause of wrinkling upon formation of the first photosensitive resin composition layer by transferring the photosensitive resin composition (1) to the substrate. As examples of the tri- or higher functional epoxy resin having such favorable properties, there may be mentioned a phenol-novolak type epoxy resin, a cresol-novolak type epoxy resin, a bisphenol A-novolak type epoxy resin and a tri- or higher functional epoxy resin having an oxycyclohexane skeleton. As commercially available epoxy resins, there are mentioned “EHPE (trademark) 3150” (product of Daicel Corporation), “jER (trademark) 157S70” and “jER (trademark) 1031S” (products of Mitsubishi Chemical Corporation), and “EPICLON (trademark) N-865” and “EPICLON (trademark) N-690” (products of DIC Corporation).
Incidentally, the softening point in the present specification means a softening point measured by the ring and ball method specified in JIS K 7234.
The bifunctional epoxy resin (b) contained in the photosensitive resin composition (1) is used as a binder for improving the film strength of the photosensitive resin composition (1) and is desired to have a weight-average molecular weight higher than that of the tri- or higher functional epoxy resin. Specifically, the bifunctional epoxy resin (b) desirably has a weight-average molecular weight (Mw) of 5,500 to 60,000 and a softening point of 90° C. or more. If the weight-average molecular weight is less than 5,500, the film strength is not improved, and so the photosensitive resin composition (1) and the photosensitive resin composition (2) formed into respective films may greatly fall in the opening of the substrate in some cases upon the transfer of the photosensitive resin composition (2) on to the photosensitive resin composition (1) or upon another thermal process. When the photosensitive resin composition (1) and the photosensitive resin composition (2) greatly fall in the opening, the heights of the respective photosensitive resin composition layers become uneven. Even if the softening point is less than 90° C., the same falling-in problem may occur in some cases. If the weight-average molecular weight (Mw) is more than 60,000 on the other hand, the crosslinking density of the photosensitive resin composition (1) is lowered, and so the stability of its pattern shape is lowered. The bifunctional epoxy resin having desired properties as described above is favorably an epoxy resin having a bisphenol skeleton, particularly favorably an epoxy resin having a bisphenol A skeleton. Examples of commercially available epoxy resins include “jER (trademark) 1004”, “jER (trademark) 1007”, “jER (trademark) 1009”, “jER (trademark) 1010” and “jER (trademark) 1256” (products of Mitsubishi Chemical Corporation), and “EPICLON (trademark) 4050” and “EPICLON (trademark) 7050” (products of DIC Corporation). The weight-average molecular weights (Mw) of these resins can be calculated in terms of polystyrene by means of a gel permeation chromatograph (manufactured by, for example Shimadzu Corporation).
The mixing ratio between the tri- or higher functional epoxy resin (a) and the bifunctional epoxy resin (b) satisfies (b)/(a)≦1.5 in terms of mixing ratio by mass, and the weight-average molecular weight (Mw) of the photosensitive resin composition (1) falls within a range of 4,500 to 11,000. In the expression indicating the mixing ratio by mass in the present specification, “(a)” is the mass of the tri- or higher functional epoxy resin (a), and “(b)” is the mass of the bifunctional epoxy resin (b). The bifunctional epoxy resin (b) is high in epoxy equivalent and low in reactivity compared with the tri- or higher functional epoxy resin (a). Accordingly, if the mixing ratio by mass is higher than 1.5, i.e., (b)/(a)>1.5, the crosslinking density of the resulting photosensitive resin composition (1) is lowered, curing thereof becomes insufficient, and pattern accuracy is lowered. If the stability of the pattern shape is lowered, irregularity cay be caused on side walls of the pattern, and so the pattern may not be formed with desired accuracy in some cases. As a result, insufficient curing or lowering of the stability of the pattern shape may cause the lowering of adhesion between the photosensitive resin composition (1) and the substrate in some cases. On the other hand, if the weight-average molecular weight (Mw) of the photosensitive resin composition (1) is more than 11,000 even when the mixing ratio by mass (b)/(a) is 1.5 or less, the crosslinking density is lowered to cause the same problem. If the weight-average molecular weight (Mw) of the photosensitive resin composition (1) is less than 11,000 on the other hand, the film strength of the photosensitive resin composition (1) becomes insufficient, and the falling-in at the opening of the substrate occurs.
The photoacid generator is favorably a sulfonic acid compound, a solfonium salt compound, an iodonium salt compound, a disulfone-based compound or a phosphoric acid compound. Examples of commercially available products thereof include “ADEKA OPTOMER SP-170”, “ADEKA OPTOMER SP-172” and “ADEKA OPTOMER SP-150” (all, trade names, products of ADEKA CORPORATION), “BBI-103” and “BBI-102” (both, trade names, products of Midori Kagaku Co., Ltd.), “IBPF”, “IBCF”, “TS-01” and “TS-91” (all, trade names, products of SANWA CHEMICAL CO., LTD.), “CPI-210”, “CPI-300” and “CPI-410” (all, trade names, products of San-Apro Ltd.), and “Irgacure (trademark) 290” (product of BASF Japan Ltd.). These photoacid generators may also be used in any combination thereof. In addition, a silane coupling agent may also be added for the purpose of improving adhesion. Examples of commercially available silane coupling agents include “A-187” (trade name, product of Momentive Performance Materials Inc.). Further, a sensitizer such as an anthracene compound, a basic substance such as an amine or an acid generator generating toluenesulfonic acid which is weakly acidic (pKa=−1.5 to 3.0) may also be added for the purpose of improving pattern resolution and controlling sensitivity. Examples of commercially available acid generators which generate toluenesulfonic acid include “TPS-1000” (trade name, product of Midori Kagaku Co., Ltd.) and “WPAG-367” (trade name, product of Wako Pure Chemical industries, Ltd.).
The photosensitive resin composition (2) requires that its cured product has mechanical strength and further requires to take resolution as a photographic material into consideration. Therefore, a negative epoxy resin composition containing, as a main component, an epoxy resin such as a bisphenol A novolak type epoxy resin, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin or a tri- or higher functional epoxy resin having an oxycyclohexane skeleton is suitably used as the photosensitive resin composition (2). The use of the epoxy resin having a tri- or higher valent epoxy group enables three-dimensionally crosslinking of the cured product, and is suitable for obtaining desired properties. Examples of commercially available epoxy resins usable in the photosensitive resin composition (2) include “CELLOXIDE (trademark) 2021”, “GT-300 Series” and “GT-400 Series” (both, trade names) and “EHPE (trademark) 3150” (all, products of Daicel Corporation), “jER (trademark) 157S70” (product of Mitsubishi Chemical Corporation), and “EPICLON (trademark) N-690” and “EPICLON (trademark) N-865” (products of DIC Corporation). A photopolymerization initiator to be added into the above-described epoxy resin composition is favorably a sulfonic acid compound, a diazomethane compound, a solfonium salt compound, an iodonium salt compound or a disulfone-based compound. Examples of commercially available products thereof include “ADEKA OPTOMER SP-170”, “ADEKA OPTOMER SP-172” and “ADEKA OPTOMER SP-150” (all, trade names, products of ADEKA CORPORATION), “BBI-103” and “BBI-102” (both, trade names, products of Midori Kagaku Co., Ltd.), “IBPF”, “IBCF”, “TS-01” and “TS-91” (all, trade names, products of SANWA CHEMICAL CO., LTD.), “CPI-210”, “CPI-300” and “CPI-410” (all, trade names, products of San-Apro Ltd.), and “Irgacure (trademark) 290” (product of BASF Japan Ltd.). In addition, a silane coupling agent may also be added into the photosensitive resin composition (2) for the purpose of improving adhesion. Examples of commercially available silane coupling agents include “A-187” (trade name, product of Momentive Performance Materials Inc.). Further, a sensitizer such as an anthracene compound, a basic substance such as an amine and an acid generator which generates toluenesulfonic acid and is weakly acidic (pKa=−1.5 to 3.0) may also be added for the purpose of improving pattern resolution and controlling sensitivity. Examples of commercially available acid generators which generate toluenesulfonic acid include “TPS-1000” (trade name, product of Midori Kagaku Co., Ltd.) and “WPAG-367” (trade name, product of Wako Pure Chemical industries, Ltd.).
Further, “SU-8 Series” (trade name) and “KMPR (trademark) 1000” (products of MicroChem Corp.), and “TMMR (trademark) 52000” and “TMMF (trademark) 52000” (products of TOKYO OHKA KOGYO CO., LTD.) which are commercially available as negative resists may also be used for the photosensitive resin composition (2).
The present invention will hereinafter be described in more detail by the following Examples. However, the present invention is not limited to these Examples.
In respective Examples, photosensitive resin compositions (1) were prepared according to their corresponding compositions shown in Tables 1 and 2. Incidentally, in both Tables, the compositions are indicated by parts by mass, and the product names in both Tables conform to the trade names of the epoxy resins and chemicals mentioned above as favorably usable products. In addition, polyethylene glycol monomethacrylate (PEGMA) was used as a solvent dissolving the photosensitive resin composition. A photoacid generator (CPI-210S) was added at a proportion of 0.5% by mass to the total mass of a tri- or higher functional epoxy resin (a) and a bifunctional epoxy resin (b). In addition, a silane coupling agent was added at a proportion of 5% by mass to the same total mass. The weight-average molecular weights (Mw) shown in both Tables are values in terms of polystyrene as measured by means of a gel permeation chromatograph (manufactured by Shimadzu Corporation). A liquid discharge head using each of the photosensitive resin compositions of the above-described compositions was prepared according to the steps illustrated in
First, the photosensitive resin composition (1) was applied on to a PET film having a thickness of 100 μm and baked for 5 minutes at 90° C. to evaporate the PEGMA solvent and form a film having a thickness of 15 μm. Then, the film of the photosensitive resin composition (1) was transferred to a substrate 2 in which a discharge energy generating element 1 and a supply path 3 have been provided in advance in a form of a dry film while applying heat of 80° C. by means of a laminating method. The supply path 3 of the substrate 2 is a hole opening to surfaces of the substrate 2, and this hole was covered with the photosensitive resin composition (1). A first photosensitive resin composition layer 10 was formed as illustrated in
A photosensitive resin composition (2) shown in Table 3 was then applied on to a PET film having a thickness of 100 μm and baked for 5 minutes at 90° C. to form a film having a thickness of 10 μm. As illustrated in
In respective Examples, PEGMA was used as a solvent to prepare photosensitive resin compositions (1) according to their corresponding compositions shown in Table 4. Proper amounts of two kinds of photoacid generators which were different in sensitivity and an acid generator (TPS-1000) were added into the photosensitive resin compositions (1). In addition, a silane coupling agent (A-187) was added in an amount of 5% by mass to the total mass of a tri- or higher functional epoxy resin (a) and a bifunctional epoxy resin (b). The composition of a photosensitive resin composition (2) was as shown in Table 5. These photosensitive resin compositions (1) and the photosensitive resin composition (2) were used to obtain liquid discharge heads according to the same production process as in Example 1. At this time, the amount of exposure to the first photosensitive resin composition layer 10 formed of the photosensitive resin composition (1) was controlled as shown in Table 4, and the amount of exposure to the second photosensitive resin composition layer 12 formed of the photosensitive resin composition (2) was controlled to 1,200 J/m2.
In respective Examples, PEGMA was used as a solvent to prepare photosensitive resin compositions (1) according to their corresponding compositions shown in Table 6, and liquid discharge heads were obtained according to the same production process as in Example 1. The composition of the photosensitive resin composition (2) was the same as Example 1, and amounts of exposure to the respective photosensitive resin composition layers were also be the same as Example 1.
An ink composed of ethylene glycol/urea/isopropylalcohol/N-methylpyrrolidone/black dye/water at a mass ratio of 5/3/2/5/3/82 was filled into each of the liquid discharge heads prepared in Examples 1 to 29 and Comparative Examples 1 to 8 to conduct printing. In addition, a falling-in amount (L) which is a depth of falling-in of the photosensitive resin composition layer above the supply path 3 was measured after the lamination of the photosensitive resin composition layer 12 formed of the photosensitive resin composition (2) in the production process of each liquid discharge head. As illustrated in
The flow path 5 of each liquid discharge head prepared was observed at a magnification of 100 times through a light microscope (manufactured by Nikon Corporation) for the purpose of examining pattering accuracy upon the patterning of the photosensitive resin composition layers, so as to confirm whether the ink seeks into the flow path forming member 4 or not. In addition, unevenness of pattern side walls of the flow path forming member 4 was observed at a magnification of 5,000 times through a scanning electron microscope (SEM, manufactured by Hitachi, Ltd.). The pattern shape was evaluated according to the evaluation criterion shown in Table 8 from these confirmation and observation results. Evaluation results of the pattern shape are shown in Tables 1, 2, 4 and 6.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary 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. 2014-194701, filed Sep. 25, 2014 and Japanese Patent Application No. 2015-130967, filed Jun. 30, 2015 which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-194701 | Sep 2014 | JP | national |
| 2015-130967 | Jun 2015 | JP | national |
