Photosensitive structure, method for manufacturing the photosensitive structure, and inkjet recording head

Abstract

To provide a photosensitive structure which can achieve both adhesion between a substrate and a negative type photosensitive resin composition, and pattern shape reproducibility while suppressing increase in sensitivity to light of the negative type photosensitive resin composition.SOLUTION: A photosensitive structure has a substrate having a hydroxyl group on a first surface, and a cured product of a negative type photosensitive resin composition arranged on the substrate, wherein the negative type photosensitive resin composition contains an epoxy compound (A), a photobase generator (B), and an aromatic compound (C), and the aromatic compound (C) is a specific compound having two functional groups selected from an unsubstituted amino group (-NH2), a hydroxyl group (-OH) or a carboxyl group (-COOH).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photosensitive structure, a method for producing the photosensitive structure, and an ink jet recording head using the photosensitive structure. [Background technology]

[0002] In recent years, photolithography, a technique for producing structures of desired shapes by applying a negative-type photosensitive resin composition to a substrate, exposing the composition through a mask with a predetermined pattern, and then removing the unexposed portions, has attracted attention in industrial fields such as semiconductors and printing. High adhesion between the substrate and the negative-type photosensitive resin composition is required because improving adhesion between the substrate and the negative-type photosensitive resin composition can impart durability to external forces such as liquid components and rubbing. In particular, when the structure is applied to a recording head used in an inkjet printer, improving adhesion can prevent the resin from peeling from the substrate when the head surface is wiped. This is expected to increase the number of times the recording head can be used and expand ink flexibility, such as compatibility with a variety of inks.

[0003] Various methods are known for improving the adhesion between a substrate and a negative-type photosensitive resin composition. Among these, a commonly used method is to use a photoacid generator to increase the reactivity of the resin and strengthen the bond between the negative-type photosensitive resin composition and the substrate, thereby improving adhesion. However, in photocationic polymerization using a photoacid generator, acid remains after the fabrication of the structure, which can cause problems such as denaturation and corrosion of the substrate or resin due to basic liquids, such as ink (often adjusted to a pH of 7 to 11 to ensure the solubility stability of colorants). Therefore, in Patent Document 1, a structure is fabricated by photocationic polymerization using a photobase generator instead of a photoacid generator. This results in a structure that is less susceptible to dissolution or denaturation in basic liquids than conventional structures. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-341442 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-330270 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, conventional anionic polymerization has the following problems. First, it is known that anionic polymerization has a slow reaction rate, which makes it difficult for the reaction to form bonds between the negative photosensitive resin composition and the substrate to proceed, thereby weakening the bond between them. This poses the problem of the cured resin composition peeling off from the substrate upon contact with the liquid. Note that, in the case of a flow path-forming member in an inkjet head, for example, "upon contact with the liquid" refers to the timing after filling with ink and exposing for a certain period of time. On the other hand, a method for increasing the reaction rate and strengthening the above-mentioned bond is known to be the addition of a base amplifier that decomposes under the action of a base to generate a base. However, as the amount of base amplifier added increases, the sensitivity of the negative photosensitive resin composition to light increases, resulting in a problem of reduced pattern shape reproducibility upon exposure.

[0006] The present invention aims to provide a structure (hereinafter also referred to as a "photosensitive structure") that can suppress an increase in the sensitivity of a negative-type photosensitive resin composition to light while simultaneously achieving good adhesion between a substrate and the negative-type photosensitive resin composition and pattern shape reproducibility, and an inkjet recording head that uses the photosensitive structure. [Means for solving the problem]

[0007] One aspect of the present invention is a photosensitive structure having a substrate having a hydroxyl group on a first surface thereof and a cured product of a negative-type photosensitive resin composition disposed on the substrate, wherein the negative-type photosensitive resin composition contains an epoxy compound (A), a photobase generator (B), and an aromatic compound (C), and the aromatic compound (C) is a compound represented by the following general formula (1):

[0008] [ka]

[0009] (In general formula (1), four of R1 to R6 each independently represent a hydrogen atom or an alkyl group, and the remaining two each independently represent a functional group selected from an unsubstituted amino group (-NH2), a hydroxyl group (-OH), or a carboxyl group (-COOH). However, the two functional groups selected from an unsubstituted amino group, a hydroxyl group, or a carboxyl group are different from each other.) [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain a photosensitive structure that can suppress an increase in the sensitivity of a negative photosensitive resin composition to light, while simultaneously achieving good adhesion between a substrate and the negative photosensitive resin composition and good pattern shape reproducibility, and an inkjet recording head that uses the photosensitive structure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram showing an example of how an aromatic compound (C) forms a crosslinked structure between a substrate and an epoxy compound. [Figure 2] 5A to 5C are diagrams showing an example of a manufacturing flow of an inkjet recording head according to the present invention. [Figure 3] FIG. 1 is a diagram illustrating a method for measuring adhesion. DETAILED DESCRIPTION OF THE INVENTION

[0012] The photosensitive structure of the present invention comprises a substrate and a cured product of a negative-tone photosensitive resin composition disposed on the substrate. The structure is characterized in that hydroxyl groups are present on a first surface of the substrate, and the negative-tone photosensitive resin composition contains an epoxy compound (A), a photobase generator (B), and an aromatic compound (C), with the aromatic compound (C) having a structure represented by the general formula (1). By using a substrate having hydroxyl groups and including the aromatic compound (C) represented by the general formula (1), an increase in the amount of base generated in the resin composition can be suppressed. Furthermore, the unsubstituted amino group, hydroxyl group, or carboxyl group contained in the aromatic compound (C) forms a hydrogen bond with the hydroxyl group of the substrate. Furthermore, these functional groups have a high affinity for epoxy groups. Therefore, the aromatic compound (C) reacts with the hydroxyl group of the substrate and the epoxy compound (A) to form a crosslinked structure, improving adhesion between the substrate and the negative-tone photosensitive resin composition. This improves the adhesion between the substrate and the negative photosensitive resin composition while maintaining the sensitivity of the negative photosensitive resin composition to light. An example of the formation of a crosslinked structure between the aromatic compound (C) and the epoxy compound and the hydroxyl group of the substrate is shown in Figure 1. Next, an embodiment of the present invention will be described in detail.

[0013] <Photosensitive structure> [substrate] Substrates applicable to the fabrication of the photosensitive structure according to the present invention have hydroxyl groups on at least their first surface. The first surface of the substrate refers to the surface of the substrate on which the negative-type photosensitive resin composition according to the present invention is disposed. Substrates having hydroxyl groups are commonly used, for example, silicon substrates with hydroxyl groups introduced therein. Examples of methods for introducing hydroxyl groups into substrates include plasma treatment. Generally, plasma is an ionized gaseous state consisting of various active species, such as ions, electrons, and radicals. Plasma treatment can activate the surface of a silicon substrate and provide reactive active groups to the surface. Examples of plasma treatment include the low-pressure plasma treatment described in JP 2012-126107 A. In the low-pressure plasma treatment, a mixture of a non-reactive gas, such as argon gas, and oxygen gas is preferably used to hydrophilize the substrate surface. Furthermore, the oxygen gas content in the mixture is preferably 10% to 25%.

[0014] [Negative-type photosensitive resin composition] (Epoxy compound (A)) The epoxy compound (A) is an epoxy resin having at least two epoxy groups per molecule. Examples include, but are not limited to, a reaction product of bisphenol A with epichlorohydrin, a reaction product of bromobisphenol A with epichlorohydrin, a reaction product of phenol novolac or o-cresol novolac with epichlorohydrin, and a polyfunctional epoxy resin having an oxycyclohexane skeleton. Furthermore, using an epoxy compound that is solid at room temperature is preferred because it suppresses the diffusion of active polymerization species generated by light irradiation into the epoxy resin, allowing for excellent patterning precision and shape. The epoxy equivalent of the epoxy compound is preferably not more than 1000. When the epoxy equivalent is not more than 1000, a decrease in crosslink density during the curing reaction can be suppressed, and a decrease in adhesion and liquid resistance can be prevented.

[0015] (Photobase Generator (B)) The photobase generator (B) can be any substance that generates a base upon irradiation with light, without any particular limitation. Specific examples include ammonium carboxylate salts, α-aminoacetophenone derivatives, TPS-OH, NBC-101, and ANC-101 (all trade names) manufactured by Midori Chemical Co., Ltd., N-(2-nitrobenzyloxycarbonyl)imidazole, N-(3-nitrobenzyloxycarbonyl)imidazole, and N-(4-nitrobenzyloxycarbonyl)imidazole. The amount of the photobase generator (B) added is not particularly limited as long as it is an amount that can cure the epoxy compound (A). Specifically, the amount of the photobase generator (B) added can be 3% by mass or more relative to the epoxy compound (A).

[0016] Furthermore, a small amount of a base amplifier (D) may be added to the negative photosensitive resin composition as a compound that complements the role of the photobase generator (B). The base amplifier (D) can be any substance that decomposes under the action of a base to generate a basic substance, and is not particularly limited. Specific examples include the urethane compounds described in Patent Document 2. The urethane compound may have two or more urethane bonds. Among the urethane compounds described in Patent Document 2, urethane compounds represented by the following general formula (2) or (3) are preferably used.

[0017] [ka]

[0018] In general formula (2), R 11 and R 12 each independently represents a hydrogen atom, a substituent, or an electron-withdrawing group, at least one of which is an electron-withdrawing group; R 13 and R 14R each independently represents a hydrogen atom or a substituent. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms; a cycloalkyl group having 5 to 10 carbon atoms, preferably 6 to 8 carbon atoms; an aryl group having 6 to 14 carbon atoms, preferably 6 to 10 carbon atoms; and an arylalkyl group having 7 to 15 carbon atoms, preferably 7 to 11 carbon atoms. Examples of the electron-withdrawing group include a fluorenyl group, an organic sulfoxide group, a cyano group, a nitro group, an ester group, a carbonyl group, an amide group, and a pyridyl group. 11 and R 12 may be bonded to each other to form a ring, for example, R 11 and R 12 A may form a fluorenyl group. A represents an unsubstituted amino group, a mono-substituted amino group, or a di-substituted amino group, and in the di-substituted amino group, two substituents may be bonded to each other to form a nitrogen-containing ring. Examples of the substituent on the amino group include organic groups having 1 to 18 carbon atoms, such as alkyl groups, cycloalkyl groups, aryl groups, and arylalkyl groups.

[0019] In general formula (3), R 11 ~R 14 is R in the general formula (2). 11 ~R 14 It is synonymous with R. 11 ' and R 12 R ′ each independently represents a hydrogen atom, a substituent, or an electron-withdrawing group, at least one of which is an electron-withdrawing group; 13 ' and R 14 R' each independently represents a hydrogen atom or a substituent. Examples of the substituent and electron-withdrawing group include the same as those exemplified in general formula (2). 11 ' and R 12 ' may be bonded to each other to form a ring, for example, R 11 ' and R 12' may form a fluorenyl group. Y represents an alkylene group having 1 to 8 carbon atoms, preferably 2 to 6 carbon atoms. m and n each independently represent a number of 1 to 6, preferably 2 to 4, and m+n is 4 to 12, preferably 4 to 8. p and q each independently represent a number of 1 to 6, preferably 2 to 4, and p+q is 4 to 12, preferably 4 to 8. The urethane compound represented by the general formula (2) or (3) can be synthesized by the method described in Patent Document 2.

[0020] When the negative-tone photosensitive resin composition contains a base amplifier (D), the content thereof is preferably 1 mole or less per mole of the photobase generator (B). As described above, the base amplifier (D) promotes an increase in the sensitivity of the negative-tone photosensitive resin composition. However, if the amount of the base amplifier (D) added per mole of the photobase generator (B) is 1 mole or less, a decrease in pattern shape reproducibility can be suppressed.

[0021] (Aromatic compounds (C)) The aromatic compound (C) is a compound that can react with the hydroxyl groups of the substrate and the epoxy compound (A) to form a crosslinked structure, and specifically has a structure represented by the following general formula (1).

[0022] [ka]

[0023] The reason why a benzene-type aromatic compound was selected as the additive to be contained in the negative photosensitive resin composition is as follows. First, comparing linear compounds with aromatic compounds, the latter are preferred because they have rigidity and increase crosslinking strength. Furthermore, aromatic compounds generally include benzene, naphthalene, and anthracene types. However, naphthalene and anthracene structures undergo triplet energy transfer upon irradiation with light, resulting in a triplet state and exhibiting a sensitizing effect. As a result, the sensitivity of the negative-tone photosensitive resin composition increases, making them unsuitable as additives for use in the present invention. For these reasons, benzene-type aromatic compounds are suitable as additives to be incorporated into negative-tone photosensitive resin compositions.

[0024] Of R1 to R6 in general formula (1), four independently represent a hydrogen atom or an alkyl group, and the remaining two independently represent a functional group selected from an unsubstituted amino group (-NH2), a hydroxyl group (-OH), or a carboxyl group (-COOH). However, the two functional groups selected from an unsubstituted amino group, a hydroxyl group, or a carboxyl group are different from each other. The number of carbon atoms in the alkyl group is not particularly limited, but the fewer the number the better. Specifically, an alkyl group having 1 to 3 carbon atoms is preferred. Furthermore, the two functional groups selected from an unsubstituted amino group, a hydroxyl group, or a carboxyl group are preferably a combination of an unsubstituted amino group and a carboxyl group. The reason for this is explained below.

[0025] First, considering the reactivity of the epoxy group with the aromatic compound (C), the reaction occurs when the nucleophilic functional group (Nu) of the aromatic compound (C) attacks the carbon atom of the epoxy group, transferring an electron to the oxygen atom that previously constituted the epoxy (see reaction formula (I) below). Therefore, it is preferable that one of R1 to R6 in the aromatic compound (C) is a functional group with stronger nucleophilicity. Since the nucleophilicity of the unsubstituted amino group, hydroxyl group, and carboxyl group increases in this order, the unsubstituted amino group is the most preferable nucleophilic functional group in the aromatic compound (C).

[0026] [ka]

[0027] On the other hand, the bond between the hydroxyl groups on the substrate and the aromatic compound (C) is mainly a hydrogen bond. Hydrogen bonds are generated by the imbalance of electrons due to polarization within the molecule, so functional groups with large polarization are preferred. Comparing unsubstituted amino groups, hydroxyl groups, and carboxyl groups, the carboxyl group has the greatest polarization and is more likely to imbalance electrons, making it more likely to form hydrogen bonds. Therefore, a carboxyl group is desirable as the hydrogen-bonding functional group possessed by the aromatic compound (C). From the above, it is preferable that the aromatic compound (C) has an unsubstituted amino group and a carboxyl group. The substitution positions of the two functional groups selected from an unsubstituted amino group, a hydroxyl group, or a carboxyl group may be in any of the ortho, para, and meta configurations, but are preferably in the para configuration.

[0028] Furthermore, as a result of extensive investigation, it was found that the content of the aromatic compound (C) in the negative-type photosensitive resin composition is preferably 0.065 mol or more and 0.130 mol or less per mole of epoxy group contained in the epoxy compound (A). When the content of the aromatic compound (C) per mole of epoxy group is 0.065 mol or more, a sufficient crosslinking structure is formed between the hydroxyl groups and the epoxy groups of the substrate, further improving adhesion. The present inventors also investigated the effect on adhesion when the content of the aromatic compound (C) per mole of epoxy group is changed. As a result, it was found that the adhesion is maximized when the content of the aromatic compound (C) is in the range of 0.078 to 0.117 mol, and that there is no change in adhesion even if the aromatic compound (C) is added in a larger amount. Therefore, it is more preferable that the content of the aromatic compound (C) in the negative-type photosensitive resin composition is 0.078 to 0.117 mol per mole of epoxy group contained in the epoxy compound (A). This range is within ±10% of the range in which the adhesion becomes stable at its maximum value.

[0029] (Other ingredients) In addition to the above components, additives such as a silane coupling agent and a flexibility-imparting agent may be added to the negative photosensitive resin composition according to the present invention as needed. The silane coupling agent is added for the purpose of further enhancing the adhesion between the substrate and the negative photosensitive resin composition. The negative photosensitive resin composition according to the present invention may also contain a solvent for dissolving the above components.

[0030] <Method for manufacturing photosensitive structure> The photosensitive structure according to the present invention can be obtained by applying a negative photosensitive resin composition containing the above-described components to a first surface of a substrate having hydroxyl groups on the first surface to form a coating film of the negative photosensitive resin composition, and then curing the coating film. That is, the method for producing the photosensitive structure according to the present invention includes at least the following steps (i) to (iii): (i) providing a substrate having hydroxyl groups on a first surface; (ii) applying a negative-type photosensitive resin composition containing an epoxy compound (A), a photobase generator (B), and an aromatic compound (C) having a structure represented by general formula (1) onto a first surface of the substrate having a hydroxyl group to form a coating film; (iii) A step of curing the coating film. This provides a photosensitive structure according to the present invention having a substrate and a cured product of the negative photosensitive resin composition on the substrate.

[0031] In step (iii), the coating film of the negative photosensitive resin composition according to the present invention is preferably cured by anionic polymerization. In photocationic polymerization using a photoacid generator, the acid generation rate is generally fast and the amount of acid generated is large, so that acid is likely to remain after the curing reaction. Therefore, when the aromatic compound (C) contains an unsubstituted amino group, the acid remaining after the curing reaction reacts with the unsubstituted amino group in the aromatic compound (C) and causes deterioration. The conditions for the heat treatment in the anionic polymerization may be appropriately set depending on the exposure dose and the type of epoxy compound (A) used, etc. The exposure dose is, for example, 4000 J / m 2 ~7000J / m 2The heating temperature can be, for example, 80° C. to 110° C. The heating time can be, for example, 3 minutes to 6 minutes.

[0032] <Inkjet recording head> The photosensitive structure according to the present invention can be used as a part of an inkjet recording head. Specifically, the substrate having a hydroxyl group on the first surface of the photosensitive structure according to the present invention can be used as a substrate in the inkjet recording head, and the cured product of the negative photosensitive resin composition according to the present invention can be used as a flow path forming member in the inkjet recording head. FIG. 2 is a schematic cross-sectional view showing an example of a manufacturing flow of an inkjet recording head according to the present invention. As shown in FIG. 2(a), an energy generating element 1 such as an electrothermal conversion element or a piezoelectric element is formed on a first surface (the surface to which the hydroxyl groups are bonded) of a substrate 2 having hydroxyl groups. The substrate may be made of glass, ceramics, plastic, metal, or the like. Generally, various functional layers such as a protective layer are provided to improve the durability of the energy generating element, and such functional layers may also be provided in the present invention. A mold 3 of an ink flow path is formed on the substrate, preferably using a positive resist. Next, a resin layer 4 is formed on the ink flow path mold 3 using a negative photosensitive resin composition according to the present invention (FIG. 2(b)). In this case, the materials of the composition for forming the resin layer 4 may be dissolved in a solvent to prepare a solution, and the solution may be applied to the ink flow path mold 3 by a spin coating method, a roll coating method, or the like to form the resin layer 4. However, it is necessary to select a solvent that does not dissolve the resin that constitutes the ink flow path mold 3. When forming the resin layer 4 using a negative photosensitive resin composition, the film thickness of the resin layer 4 can be, for example, 16 μm to 25 μm. Next, as shown in FIG. 2(c), pattern exposure is performed through a photomask 6. The pattern exposure can be performed using ultraviolet light, deep-UV light, electron beams, X-rays, or the like, depending on the photosensitive region of the photobase generator used. After exposure, a heat treatment may be performed as appropriate. Next, development is performed to remove the unexposed portions 4A, thereby forming discharge ports 7 (FIG. 2(d)). Next, a mask (not shown) for forming an ink supply port 8 is appropriately placed on the second surface of the substrate (the surface opposite to the first surface), and after protecting the surface of the substrate with a rubber film, the ink supply port 8 is formed by anisotropic etching (FIG. 2(e)). The rubber film is then removed, and the entire surface of the substrate is irradiated with ultraviolet light to decompose and remove the positive resist, forming a flow path 9 (FIG. 2(f)). Furthermore, a heat treatment is performed to completely cure the negative photosensitive resin composition, and then electrical connection and ink supply means are appropriately arranged to obtain an inkjet recording head. The inkjet recording head shown in FIG. 2(f) uses a cured product of the negative photosensitive resin composition according to the present invention as the flow path-forming member 5. [Example]

[0033] Examples and comparative examples are shown below, but the present invention is not limited to these. For evaluation, photosensitive structures were fabricated using a silicon substrate having hydroxyl groups (except Comparative Example 3) and the negative photosensitive resin composition of each Example and Comparative Example, and pattern shape reproducibility and adhesion were evaluated. Furthermore, inkjet recording heads were fabricated using the negative photosensitive resin compositions of each Example and Comparative Example, and peel resistance between the substrate and the negative photosensitive resin composition was evaluated.

[0034] [Example 1] <Hydrophilic treatment of silicon substrate> In order to introduce hydroxyl groups into the silicon substrate, a low-pressure plasma treatment described in JP 2012-126107 A was performed. In the low-pressure plasma treatment, a mixed gas of argon gas and oxygen gas was used to hydrophilize the substrate surface. The ratio of oxygen gas in the mixed gas was set to 20%. This resulted in the production of a silicon substrate with hydroxyl groups.

[0035] <Preparation of negative-type photosensitive resin composition> First, 100 g of EHPE3150 (trade name, manufactured by Daicel Chemical Industries, Ltd.) as epoxy compound (A) was added to 70 g of xylene and dissolved by stirring for 3 days. Subsequently, 5 g of SILQUEST A-187 (trade name, manufactured by Momentive Performance Materials, Inc.) as a silane coupling agent, 5 g of dimethylammonium α-naphthylglyoxylate as photobase generator (B), 10 g of 4,4'-[bis[[(9-fluorenylmethyl)oxy]carbonyl]trimethylene]dipiperidine as base multiplier (D), and 3 g of anthranilic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) as aromatic compound (C) were added to the resulting solution and stirred for 5 hours to obtain a negative-tone photosensitive resin composition. In this negative-tone photosensitive resin composition, the content of aromatic compound (C) per mole of epoxy groups contained in epoxy compound (A) was 0.039 moles.

[0036] <Coating of negative photosensitive resin composition onto substrate> Next, the negative photosensitive resin composition was applied onto the substrate by the method described below. First, the negative photosensitive resin composition obtained was applied to the first surface of the silicon substrate having hydroxyl groups by spin coating to a film thickness of 20 μm, and then heat-treated at 60° C. for 3 minutes in a vacuum environment to form a coating film.

[0037] <Fabrication of photosensitive structure> Next, the coating film on the substrate was exposed to light at an exposure dose of 5000 J / m using an i-line exposure stepper (manufactured by Canon Inc.). 2The coated film was exposed to light at 1000 K, and then heated at 95°C for 4 minutes. After washing with a mixed solution of methyl isobutyl ketone and xylene, the coated film was heated at 140°C for 4 minutes. Finally, the coated film was cured by heating at 200°C for 1 hour, thereby obtaining a photosensitive structure having a structure in which a cured product of the negative photosensitive resin composition was disposed on the substrate.

[0038] <Fabrication of Inkjet Recording Head> Next, an inkjet recording head was fabricated by the following method, the fabrication flow of which is shown in Figure 2. On the first surface of the silicon substrate 2 having hydroxyl groups, on which the energy generating elements 1 were provided, a positive resist, polymethyl isopropenyl ketone (product name: ODUR-1010, manufactured by Tokyo Ohka Kogyo Co., Ltd.), was applied to a thickness of 14 μm to form the ink flow path mold 3, and the resist was heated at 120°C for 6 minutes. Next, an ink flow path pattern was exposed using an exposure device (product name: UX3000, manufactured by Ushio Inc.), and developed with MIBK (methyl isobutyl ketone), thereby forming the ink flow path mold 3 (FIG. 2(a)). Next, the negative photosensitive resin composition prepared above was applied by spin coating to the ink flow path mold 3 from the base (substrate 2) to a film thickness of 20 μm as the resin layer 4 that would become the flow path forming member 5 having the discharge ports. Thereafter, a heat treatment was performed at 60°C for 3 minutes in a vacuum environment (FIG. 2(b)). Next, an i-line exposure stepper (manufactured by Canon Inc.) was used to expose the photoresist through a photomask 6 to an exposure dose of 5000 J / m 2 so that the ejection port formation areas were non-exposed areas 4A. 2 (Fig. 2(c)), and then heat treatment was performed at 95°C for 4 minutes. Next, development was performed using a mixed solution of xylene / MIBK=6 / 4 to remove the unexposed portion 4A, thereby forming the discharge port 7 (Fig. 2(d)). Furthermore, a mask (not shown) for forming an ink supply port 8 was appropriately placed on the second surface of the substrate (the surface opposite to the first surface), and the surface of the substrate was protected with a rubber film. The silicon substrate was then anisotropically etched to form the ink supply port 8 (Figure 2(e)). After the anisotropic etching was completed, the rubber film was removed, and the entire surface of the substrate was again irradiated with ultraviolet light using an exposure device (product name: UX3000, manufactured by Ushio Inc.). This decomposed the positive resist. The decomposed positive resist was then dissolved and removed using methyl lactate, forming a flow path 9 (Figure 2(f)). Next, to completely cure the negative photosensitive resin composition and the ink-repellent film (not shown), a heat treatment was performed at 200°C for 1 hour. After that, electrical connection and ink supply means were appropriately arranged to complete the inkjet recording head. The ink-repellent film is a thin film formed by applying and curing an ink-repellent material to the surface of the layer constituting the flow path-forming member 5. The obtained inkjet recording head comprises, as a flow path forming member 5, a cured product of the negative photosensitive resin composition.

[0039] [Examples 2 and 3, Comparative Example 1] Negative photosensitive resin compositions were prepared in the same manner as in Example 1, except that the amount of anthranilic acid added as the aromatic compound (C) was changed as shown in Table 2. Furthermore, a photosensitive structure and an ink jet recording head were produced in the same manner as in Example 1 using the obtained negative photosensitive resin composition.

[0040] Comparative Example 2 Negative photosensitive resin compositions were prepared in the same manner as in Comparative Example 1, except that the amount of 4,4'-[bis[[(9-fluorenylmethyl)oxy]carbonyltrimethylene]dipiperidine added as the base multiplier (D) was changed as shown in Table 2. Furthermore, a photosensitive structure and an ink jet recording head were produced in the same manner as in Example 1 using the obtained negative photosensitive resin composition.

[0041] Comparative Example 3 The silicon substrate was subjected to a low-pressure plasma treatment using only argon gas. Using the obtained silicon substrate (containing no hydroxyl groups), a photosensitive structure and an inkjet recording head were fabricated in the same manner as in Example 2.

[0042] <Measurement and Evaluation> [Evaluation of photosensitive structures] (Pattern shape reproducibility) The area of the pattern (the pattern when forming the ejection orifices in the resin layer 4) formed on the photosensitive structures obtained in the process of producing the inkjet recording heads according to Examples 1 to 3 and Comparative Examples 1 to 3 was measured using Vertscan 2.0 (product name) manufactured by Ryoka Systems Co., Ltd. The area of the obtained pattern (μm 2 ) and mask area (μm 2 The pattern shape reproducibility for the mask was evaluated based on the ratio of the pattern shape reproducibility to the mask, according to the following criteria. The results are shown in Table 2 as "pattern shape reproducibility." Good: The pattern area / mask area is 0.9 or more and less than 1.1. Δ: The pattern area / mask area is 0.8 or more and less than 0.9, or 1.1 or more and less than 1.2. ×: The pattern area / mask area is less than 0.8 or is 1.2 or more.

[0043] (adhesion) For the photosensitive structures prepared in Examples 1 to 3 and Comparative Examples 1 to 3, the adhesion between the substrate and the negative photosensitive resin composition was measured using the following procedure. First, as shown in FIG. 3(A), a pattern of the negative photosensitive resin composition according to each Example or Comparative Example was formed on the substrate according to each Example or Comparative Example, and the pattern was pressed with a tool (FIG. 3(B)). The pressure applied with the tool was gradually increased, and the value of the pressing force when the pattern peeled off from the substrate was measured to evaluate the adhesion. The measurement was performed using a strength measuring device "Bonding Tester PTR-10" (product name) manufactured by Rhesca Corporation. The value of the pressing force when the pattern peeled off from the substrate is called shear strength, and a higher value indicates greater adhesion between the substrate and the negative photosensitive resin composition. The results are shown as "shear strength" in Table 2.

[0044] [Evaluation of inkjet recording heads] (peeling resistance) The inks containing the ingredients shown in Table 1 below were filled into the flow paths of the inkjet recording heads prepared in Examples 1 to 3 and Comparative Examples 1 to 3, and left in an oven at 70° C. for 90 days. Carbon black was used as the black pigment.

[0045] [Table 1]

[0046] After the inkjet recording head was left standing, the bonding state between the substrate and the negative photosensitive resin composition was observed using a metallurgical microscope (product name: MX63L, manufactured by Olympus Corporation) and evaluated according to the following criteria. The results are shown in Table 2 as "peel resistance." ◯: No peeling occurred between the substrate and the negative photosensitive resin composition. ×: Peeling occurred between the substrate and the negative photosensitive resin composition, which was not observed when the inkjet head was formed.

[0047] [Table 2] [Explanation of symbols]

[0048] 2 boards 4. Resin layer that becomes a flow path forming member having a discharge port

Claims

1. A photosensitive structure comprising a substrate having a hydroxyl group on a first surface thereof and a cured product of a negative photosensitive resin composition disposed on the substrate, wherein the negative photosensitive resin composition contains an epoxy compound (A), a photobase generator (B), and an aromatic compound (C), and the aromatic compound (C) is a compound represented by the following general formula (1): 【Chemical 1】 (In general formula (1), R １ ~R ６ Among these, four independently represent a hydrogen atom or an alkyl group, and the remaining two independently represent an unsubstituted amino group (—NH ２ represents a functional group selected from an unsubstituted amino group, a hydroxyl group (—OH), or a carboxyl group (—COOH), provided that the two functional groups selected from an unsubstituted amino group, a hydroxyl group, or a carboxyl group are different from each other.

2. 2. The photosensitive structure according to claim 1, wherein in the aromatic compound (C), the two functional groups selected from an unsubstituted amino group, a hydroxyl group, and a carboxyl group are an unsubstituted amino group and a carboxyl group.

3. 3. The photosensitive structure according to claim 1, wherein in the negative photosensitive resin composition, the content of the aromatic compound (C) is 0.065 mol or more and 0.130 mol or less per 1 mol of epoxy groups in the epoxy compound (A).

4. The photosensitive structure according to any one of claims 1 to 3, wherein the negative photosensitive resin composition further contains a base multiplier (D), and the content of the base multiplier (D) is 1 mol or less per 1 mol of the photobase generator (B).

5. A method for producing the photosensitive structure according to any one of claims 1 to 4, comprising the following steps (i) to (iii): (i) providing a substrate having hydroxyl groups on a first surface; (ii) applying a negative-type photosensitive resin composition containing an epoxy compound (A), a photobase generator (B), and an aromatic compound (C) having a structure represented by general formula (1) onto the first surface of the substrate having a hydroxyl group to form a coating film; (iii) A step of curing the coating film.

6. The method for producing a photosensitive structure according to claim 5 , wherein in the step (iii), the coating film is cured by anionic polymerization.

7. 5. An inkjet recording head having the photosensitive structure according to claim 1, wherein the substrate having a hydroxyl group is used as a substrate in the inkjet recording head, and a cured product of the negative photosensitive resin composition is used as a flow path forming member in the inkjet recording head.

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