Composition for forming a coating film, coating film, gas sensor, and method for manufacturing a gas sensor.

Abstract

To provide a composition for coating film formation which enables formation of a micro coating film on an electronic base material.SOLUTION: A composition for coating film formation includes a monomer or a polymer, and satisfies at least one of the following conditions (A) to (C). (A) The composition for coating film formation includes a monomer and a polymerization initiator, does not include a solvent, and has a molecular weight of the whole monomer of 50 or more, a density of the whole monomer of 1.00 g / cm3 or more and a boiling point of the monomer of 105°C or higher, (B) the composition for coating film formation includes a monomer, a solvent and a polymerization initiator, and has a molecular weight of the whole of the monomer and the solvent of 50 or more, a density of the whole of the monomer and the solvent of 1.00 g / cm3 or more and each of the boiling point of the monomer and the solvent of 105°C or higher. and (C) the composition for coating film formation includes a monomer and a solvent, and has a weight average molecular weight of the whole polymer of 10,000 or more, and a density of the whole solvent of 0.80 g / cm3 or a boiling point of the solvent of 80°C or higher.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to a composition for forming a coating film, a coating film, a gas sensor, and a method for manufacturing a gas sensor. [Background technology]

[0002] Various printing methods such as spray coating, screen printing, gravure printing, and inkjet printing, as well as coating methods such as needle dispensers, are known for creating thin films and coatings using liquid and slurry materials in semiconductor and MEMS (Micro Electro Mechanical Systems) components. In particular, inkjet and dispenser methods for creating thin films are widely used as means of forming fine wiring patterns. While inkjet printing offers advantages in controlling coating thickness and high-speed printing, it has a narrow usable solution viscosity range, requiring careful consideration of composition for stable droplet formation and control of ink evaporation conditions (see, for example, Patent Documents 1 and 2). Dispenser printing offers a wide usable viscosity range and allows for the application of paste-like compositions, but it has challenges in high-speed application and control of application volume, making it unsuitable for application over large areas and more suitable for repairing broken wiring (see, for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-001479 [Patent Document 2] Japanese Patent Publication No. 2010-082562 [Patent Document 3] Japanese Patent Publication No. 2018-090434 [Overview of the project] [Problems that the invention aims to solve]

[0004] Monomers, polymers, or polymer composites used in semiconductors and MEMS are generally often used as resist materials, insulating films, conductive layers, etc. For example, in photolithography, the resist material is formed as a uniform thin film on a silicon substrate by spin coating or the like. On the other hand, when attempting to arrange wiring, sensitive films, etc., in arbitrary shapes, sizes, and positions within circuit boards or MEMS with complex shapes, the above methods may not be sufficient. Since there are limited methods for applying polymer solutions to minute areas (e.g., 10mm x 10mm), such as inkjet or needle dispenser methods, it is necessary to optimize the precision and suitable solutions. Furthermore, inkjet methods can only apply solutions with extremely low viscosity, thus limiting the types of solutions that can be used. For example, Patent Document 1 discloses a method for stably ejecting droplets by controlling not only the ejection speed and maximum ejection frequency, but also the solution viscosity, solution density, and droplet diameter. In the pattern formation method described in Patent Document 2, after the pattern forming material is dropped and dried by heating the substrate, the solution is further dispensed into areas with uneven film thickness caused by differences in the evaporation rate of the solution in the coated area to make the pattern uniform. Patent Document 3 proposes a material that is less prone to stringing and nozzle clogging when applying paste material with a dispenser.

[0005] As mentioned above, wiring in minute areas and sensor-sensitive films require specific sizes, thicknesses, and shapes depending on their respective applications and purposes. Therefore, the dispenser method is useful as a thin-film coating method, but there is still room for improvement in terms of solution properties that are less prone to stringing and nozzle clogging in terms of the solution and composition. In particular, when forming polymer solutions, the film is designed according to the substance that the sensor-sensitive film detects, and even if the solution does not volatilize easily with conventional coating methods such as coaters, it becomes prone to volatilization when it reaches picoliter-sized droplets, making stable droplet formation difficult in many cases, and thus thin-film formation is challenging.

[0006] Therefore, there is a need for a coating film-forming composition, a coating film, a gas sensor, and a method for manufacturing a gas sensor that can form a hardly volatile and stable droplet by an inkjet method or a dispenser method and form a minute coating film (e.g., 10,000 μm × 10,000 μm × 50 μm) on an electronic substrate.

[0007] In view of the above problems, an object of one embodiment of the present disclosure is to provide a coating film-forming composition, a coating film, a gas sensor, and a method for manufacturing a gas sensor that can form a minute coating film on an electronic substrate.

Means for Solving the Problems

[0008] Means for solving the above problems include the following embodiments. <1> A coating film-forming composition containing a monomer or a polymer and satisfying at least one of the following conditions (A) to (C). (A) The coating film-forming composition contains the monomer and a polymerization initiator, does not contain a solvent, the total molecular weight of the monomer is 50 or more, and the total density of the monomer at 20°C is 1.00 g / cm or more or the boiling point of the monomer is 105°C or more. 3 (B) The coating film-forming composition contains the monomer, a solvent, and a polymerization initiator, the total molecular weight of the monomer and the solvent is 50 or more, and the total density of the monomer and the solvent at 20°C is 1.00 g / cm or more or the boiling point of each of the monomer and the solvent is 105°C or more. 3 (C) The coating film-forming composition contains the polymer and a solvent, the total weight average molecular weight of the polymer is 10,000 or more, and the total density of the solvent at 20°C is 0.80 g / cm or more or the boiling point of the solvent is 80°C or more. 3 ​​​​​​​<2> The composition for forming a coating film according to <1>, wherein the solution viscosity at 20°C measured by a B-type viscometer is 0.5 mPa·sec to 2000 mPa·sec. <3> The composition for forming a coating film according to <1> or <2>, wherein the content of the polymer under the condition of (C) is 0.001 parts by mass to 25 parts by mass with respect to 100 parts by mass of the composition for forming a coating film. <4> The ΔE measured in terms of color difference system when formed into a cured film is 10 or less, The cured film is obtained by spin-coating the composition for forming a coating film on a cover glass of 18 mm × 18 mm and having a thickness of 0.14 mm to a thickness of about 400 μm and curing it, and is the composition for forming a coating film according to any one of <1> to <3>. <5> The composition for forming a coating film according to any one of <1> to <4>, which is applied to a micro-region having a side length or diameter of 10 mm or less. <6> The composition for forming a coating film according to <5>, which is applied to the micro-region by an inkjet method or a dispenser method. <7> The coating film formed by curing the composition for forming a coating film according to any one of <1> to <6> is used as a gas sensor sensitive film. <8> A coating film formed by curing the composition for forming a coating film according to any one of <1> to <7>. <9> The coating film according to <8>, having an average film thickness of 0.5 nm to 50 μm. <10> The coating film according to <8> or <9>, which is used as a gas sensor sensitive film. <11> A gas sensor including a sensing part, wherein the coating film according to any one of <8> to <10> is formed on the sensing part. <12> The gas sensor according to <11>, wherein the side length or diameter of one side of the coating film is 10 mm or less. <13> A method for manufacturing a gas sensor, comprising a step of forming the coating film according to any one of <8> to <10> on the sensing part of the gas sensor. <14> The coating film is applied to a minute area having a side length or diameter of 10 mm or less. <13> A method for manufacturing a gas sensor as described above. <15> The coating film is applied to a minute area having a side length or diameter of 10 mm or less by an inkjet method or a dispenser method. <13> or <14> A method for manufacturing a gas sensor as described above. [Effects of the Invention]

[0009] This disclosure provides a coating film forming composition, a coating film, a gas sensor, and a method for manufacturing a gas sensor, which can form a micro-coated film on an electronic substrate. [Modes for carrying out the invention]

[0010] The following describes in detail the forms for implementing this disclosure. However, this disclosure is not limited to the following embodiments. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit this disclosure.

[0011] In this disclosure, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages, or with the values ​​shown in the examples. In this disclosure, the amount of each component in the material means the total amount of multiple substances present in the material, unless otherwise specified, if there are multiple substances corresponding to each component in the material.

[0012] (1) Composition for coating film formation The coating film-forming compositions of this disclosure comprise monomers or polymers and satisfy at least one of the following conditions (A) to (C). Condition (A): The coating film-forming composition contains monomers and polymerization initiators, does not contain solvents, and the total molecular weight of the monomers is 50 or more, The overall density of the monomer at 20°C is 1.00 g / cm³. 3 The boiling point of the monomer must be 105°C or higher. Condition (B): The coating film-forming composition comprises a monomer, a solvent, and a polymerization initiator. The total weight-average molecular weight of the monomer and solvent is 50 or more, The total density of the monomer and solvent at 20°C is 1.00 g / cm³. 3 The boiling point of the monomer and solvent must be 105°C or higher. Condition (C): The coating film-forming composition comprises a polymer and a solvent, The overall weight-average molecular weight of the polymer is 10,000 or more, and The total density of the solvent at 20°C is 0.80 g / cm³. 3 The temperature must be above or above, or the boiling point of the solvent must be 80°C or higher.

[0013] In this disclosure, with respect to "total molecular weight of monomer," "total density of monomer at 20°C," and "boiling point of monomer" in condition (A), "monomer" refers to the monomer contained in the coating film-forming composition of condition (A). In this disclosure, the "total molecular weight of monomers" in condition (A) is the sum of the values ​​obtained by multiplying the molecular weight of each monomer contained in the coating film-forming composition by the mass fraction of each monomer. In this disclosure, the "total density of monomers at 20°C" in condition (A) is a value calculated based on the mass of each of the total monomers contained in the paint-forming composition. In this disclosure, the “boiling point of the monomer” in condition (A) refers to the boiling point of each of the monomers contained in the paint-forming composition at 1 atmosphere. In this disclosure, with respect to "total molecular weight of monomer and solvent," "total density of monomer and solvent at 20°C," and "boiling point of monomer and solvent" in condition (B), "monomer" refers to the monomer contained in the coating film-forming composition of condition (B), and "solvent" refers to the solvent contained in the coating film-forming composition of condition (B). In this disclosure, the "total molecular weight of monomers and solvents" in condition (B) is the sum of the results obtained by multiplying the molecular weight of each of the total monomers and total solvents contained in the coating film-forming composition by the respective mass fractions of the total monomers and total solvents. In this disclosure, the "total density of monomers at 20°C" in condition (B) is a value calculated based on the respective masses of all monomers and all solvents contained in the paint-forming composition. In this disclosure, “the boiling point of the monomer and the solvent” in condition (B) refers to the boiling points of all monomers and all solvents contained in the paint-forming composition at 1 atmosphere. In this disclosure, with respect to "total weight-average molecular weight of the polymer," "total density of the solvent at 20°C," and "boiling point of the solvent" in condition (C), "polymer" refers to the polymer contained in the coating film-forming composition of condition (C), and "solvent" refers to the solvent contained in the coating film-forming composition of condition (C). In this disclosure, the "overall weight-average molecular weight of the polymer" in condition (C) refers to the measured weight-average molecular weight of all polymers contained in the coating film-forming composition. In this disclosure, the "total density of the solvent at 20°C" in condition (C) is a value calculated based on the respective masses of the total polymer and the total solvent contained in the coating film-forming composition. In this disclosure, the “boiling point of the solvent” in condition (C) refers to the boiling point of each of the solvents contained in the coating film-forming composition at 1 atmosphere.

[0014] Since the coating film-forming composition of this disclosure has the above-described structure, it can form a micro-coating film (for example, 10,000 μm × 10,000 μm × 50 μmt) on an electronic substrate. More specifically, when the coating film-forming composition of this disclosure is applied to an electronic substrate by, for example, an inkjet method or a dispenser method, it forms droplets that are not easily volatile and are stable, thereby forming a micro-coating film on the electronic substrate.

[0015] The coating film-forming composition of this disclosure is a liquid composition comprising monomers, polymers, and polymer composites, and is used, for example, as a resist material, insulating film, conductive layer, protective layer, sensitive film, etc., in semiconductors and MEMS. Generally, organic materials and composite materials used in semiconductors and MEMS are limited to specific applications, such as polyimide-based resist materials and epoxy-based insulating films, because they may contaminate the semiconductor / MEMS manufacturing process or the device itself. On the other hand, if there is a method that can accurately form a coating film on specific microscopic areas of semiconductors and MEMS, the risk of device contamination will be reduced. It is presumed that a dispenser method that can dispense droplets of the coating film-forming composition of this disclosure in amounts ranging from picoliters to several microliters can form an excellent coating film. When forming a coating film on a minute area using the above coating method, the physical properties of the coating film-forming composition greatly affect whether droplets can be ejected and whether a uniform coating film can be produced. In the above method, the amount of droplets ejected from the nozzle or needle is very small, ranging from femtoliters to picoliters. Therefore, the boiling point and density of the solvent must be sufficiently high under actual usage conditions, and it must be ejected without volatilization or stringing when forming a coating film on an electronic substrate, and the droplets must remain without volatilization or stringing until they land on the electronic substrate. Even if the bulk is resistant to volatilization, in the case of mist or droplets with a large surface area, the coating film-forming composition may volatilize before the coating film is formed. As a result of this study, with the coating film-forming composition of this disclosure, stable droplets can be formed, enabling ejection and coating film formation, and a uniform coating film can be obtained even in a minute area.

[0016] In this disclosure, a micro-region is defined as a region within the coating area of ​​a coating film-forming composition on electronic devices such as semiconductors and MEMS, where one side or diameter is 10 mm or less, preferably 0.5 μm to 10 mm, more preferably 1 μm to 10 mm, even more preferably 3 μm to 8.0 mm, and most preferably 5 μm to 6.0 mm. If the micro-region is within the above range, it is easy and cost-effective to apply the coating film-forming composition of this disclosure by inkjet or dispenser method. The shape of the micro-region is preferably polygonal or circular. Examples of polygons include triangles, squares, rectangles, and pentagons.

[0017] In inkjet or dispenser methods, it is particularly easy to form droplets that are not easily volatile and are stable, thereby forming a micro-coated film on an electronic substrate. As described above, the coating film-forming composition of this disclosure can form droplets that are not easily volatile and are stable when applied to an electronic substrate, thereby forming a micro-coated film on the electronic substrate. For this reason, the coating film-forming composition of this disclosure is preferably applied to a micro-area by inkjet or dispenser method.

[0018] The coating film-forming compositions of this disclosure include monomers or polymers. Details about monomers or polymers will be described later.

[0019] (1.1) Condition (A) Under condition (A), the coating film-forming composition contains monomers and polymerization initiators, but no solvent, the overall weight-average molecular weight of the monomers is 50 or more, and the overall density of the monomers at 20°C is 1.00 g / cm³. 3 The boiling point of the monomer is 105°C or higher. When condition (A) is met, the coating film-forming composition of this disclosure can form a micro-coated film on an electronic substrate. Specifically, when the coating film-forming composition of this disclosure is applied to an electronic substrate by, for example, an inkjet method or a dispenser method, it can be easily ejected or applied, form stable droplets, and avoid bleeding after application to the electronic substrate.

[0020] (1.1.1) Physical properties Under condition (A), the total molecular weight of the monomer is 50 or more, preferably 60 or more, more preferably 70 or more, and most preferably 90 or more. The total molecular weight of the monomer may be 1000 or less, 750 or less, 500 or less, etc. The total molecular weight of the monomer is a value calculated arithmetically from its structural formula. Under condition (A), the total density of the monomer at 20 °C is preferably 1.00 g / cm 3 or more, more preferably 1.01 g / cm 3 or more, still more preferably 1.02 g / cm 3 or more, and most preferably 1.03 g / cm 3 or more. The total density of the monomer at 20 °C may be 1.50 g / cm 3 or less, 1.30 g / cm 3 or less, 1.10 g / cm 3 or less, etc. The total density of the monomer at 20 °C is a value calculated arithmetically from the mass and volume of the whole monomer. Under condition (A), the boiling point of the monomer is preferably 105 °C or more, more preferably 110 °C or more, still more preferably 115 °C or more, and most preferably 120 °C or more. The boiling point of the monomer may be 600 °C or less, 500 °C or less, 400 °C or less, etc. The boiling point of the monomer is a catalog value or a measured value by gas chromatograph distillation test method (JIS K 2254).

[0021] (1.1.2) Monomer Under condition (A), from the viewpoint of obtaining a stable droplet formation and a microcoating film with good dimensional accuracy after landing, the composition for forming a coating film of the present disclosure contains a monomer which is a polymer precursor. Examples of monomers in condition (A) include radically polymerizable monomers, more specifically vinyl compounds and vinylidene compounds. More specifically, examples include (meth)acrylate monomers, styrene monomers, acrylonitrile, (meth)acrylamide derivatives, vinyl chloride, vinyl acetate, vinylidene chloride, vinylidene fluoride, etc. Examples of (meth)acrylate monomers include monofunctional (meth)acrylates and difunctional (meth)acrylates. Examples of (meth)acrylate monomers include dimethylol tricyclodecane diacrylate, 3-(acryloyloxy)-2-hydroxypropyl methacrylate, mono(2-acryloyloxyethyl) succinate, etc. The monomers in condition (A) may be used individually or in combination of two or more. Under condition (A), the monomer content is not particularly limited. The upper limit of the monomer content is preferably 99.9 parts by mass or less per 100 parts by mass of the coating film-forming composition. The lower limit of the monomer content is preferably 90 parts by mass or more, more preferably 95 parts by mass or more, and even more preferably 98 parts by mass or more, per 100 parts by mass of the coating film-forming composition.

[0022] (1.1.3) Polymerization initiator Under condition (A), the coating film-forming composition of this disclosure contains a polymerization initiator. Examples of polymerization initiators under condition (A) include thermal polymerization initiators and photopolymerization initiators, but photopolymerization initiators are preferred to reduce thermal damage to the coating film. Examples of photopolymerization initiators include benzoin compounds, acetophenones, thioxatones, α-acyloxime esters, phenylglyoxylates, benzyls, azo compounds, diphenyl sulfide compounds, acylphosphine oxide compounds, organic dye compounds, iron-phthalocyanine compounds, benzoins, benzoin ethers, and anthraquinones. These photoradical polymerization initiators may be used individually or in combination. More specific examples of photopolymerization initiators include benzophenone, acetophenone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. The content of the polymerization initiator in condition (A) is not particularly limited. The upper limit of the polymerization initiator content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the coating film-forming composition. The lower limit of the polymerization initiator content is preferably 0.01 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the coating film-forming composition.

[0023] (1.2) Condition (B) Under condition (B), the coating film-forming composition comprises a monomer, a solvent, and a polymerization initiator, the combined molecular weight of the monomer and solvent is 50 or more, and the combined density of the monomer and solvent at 20°C is 1.00 g / cm³. 3 The boiling point of the monomer and solvent is 105°C or higher. When condition (B) is met, the coating film-forming composition of the present disclosure can form a micro-coated film on an electronic substrate. Specifically, when the coating film-forming composition of the present disclosure is applied to an electronic substrate by, for example, an inkjet method or a dispenser method, it can be easily ejected or applied, form stable droplets, and avoid bleeding after application to the electronic substrate.

[0024] (1.2.1) Physical properties Under condition (B), the total molecular weight of the monomer and solvent is 50 or more, preferably 60 or more, more preferably 70 or more, and most preferably 90 or more. The total molecular weight of the monomer and solvent may also be 1000 or less, 750 or less, 500 or less, etc. The total molecular weight of the monomer and solvent is the value calculated using structural formula arithmetic. Under condition (B), the total density of the monomer and solvent at 20°C is preferably 1.00 g / cm³. 3 The above is preferable, and more preferably 1.01 g / cm³. 3 More preferably 1.02 g / cm³ 3 In summary, the most preferred value is 1.03 g / cm³. 3 That concludes the report. The total density of the monomer and solvent at 20°C is 1.50 g / cm³. 3 Below, 1.30g / cm 3 Below 1.10g / cm 3 The following may also be used: The total density of the monomer and solvent at 20°C is calculated arithmetically from the total mass and volume of the monomer and solvent. Under condition (B), the boiling points of the monomer and solvent are preferably 105°C or higher, more preferably 110°C or higher, even more preferably 115°C or higher, and most preferably 120°C or higher. The boiling points of the monomer and solvent may also be 600°C or lower, 500°C or lower, 400°C or lower, etc. The boiling points of the monomer and solvent are catalog values ​​or measured values ​​obtained by gas chromatography distillation test (JIS K 2254).

[0025] (1.2.2) Monomers Under condition (B), the coating film-forming composition of this disclosure contains a monomer, which is a polymer precursor, from the viewpoint of obtaining stable droplet formation and a micro-coating film with good dimensional accuracy after impact. Examples of monomers under condition (B) include radically polymerizable monomers, such as vinyl compounds and vinylidene compounds. More specifically, examples include (meth)acrylate monomers, (α-methyl)styrene monomers, acrylonitrile, (meth)acrylamide derivatives, vinyl chloride, vinyl acetate, vinylidene chloride, and vinylidene fluoride. Examples of (meth)acrylate monomers include monofunctional (meth)acrylates and difunctional (meth)acrylates. Examples of (meth)acrylate monomers include dimethylol tricyclodecane diacrylate, 3-(acryloyloxy)-2-hydroxypropyl methacrylate, and mono(2-acryloyloxyethyl) succinate. Furthermore, under condition (B), by using a solvent with density, boiling point, and molecular weight significantly exceeding those of condition (B), monomers that do not satisfy condition (B) on their own can also be used. Under condition (B), monomers may be used individually or in combination of two or more. Under condition (B), the monomer content is not particularly limited. The upper limit of the monomer content is preferably 99.9 parts by mass or less, more preferably 99.0 parts by mass or less, and even more preferably 90.0 parts by mass or less, per 100 parts by mass of the coating film-forming composition. The lower limit of the monomer content is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the coating film-forming composition.

[0026] (1.2.3) Solvent Under condition (B), the coating film-forming composition contains a solvent. By including a solvent in the coating film-forming composition, the viscosity and density of the coating film-forming composition can be adjusted. Examples of solvents under condition (B) include water, alcohols such as methanol, ethanol, propanol, and butanol; hydrocarbon compounds such as n-heptane, n-octane, decane, tetradecane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene, and cyclohexylbenzene; ether compounds such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, and p-dioxane; and polar compounds such as propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, and cyclohexanone. Of these, water, alcohols, hydrocarbon compounds, carbonyl compounds, and amide compounds are preferred as solvents in condition (B) in terms of stable droplet formation and good coating film formation after impact. More preferred solvents include water, hydrocarbon compounds, amide compounds, and carbonyl compounds. Water, glycerol-added water, xylene, methylcyclohexane, cyclohexanone, dimethylformamide, and N-methyl-2-pyrrolidone are particularly preferred as solvents in condition (B). These solvents may be used individually or as mixtures of two or more. Under condition (B), the solvent content is not particularly limited. The upper limit of the solvent content is preferably 99 parts by mass or less, more preferably 95 parts by mass or less, and even more preferably 90 parts by mass or less, per 100 parts by mass of the coating film-forming composition. The lower limit of the solvent content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the coating film-forming composition.

[0027] (1.2.4) Polymerization initiator Under condition (B), the coating film-forming composition contains a polymerization initiator. Examples of polymerization initiators under condition (B) include those similar to those exemplified as polymerization initiators under condition (A). The content of the polymerization initiator in condition (B) is not particularly limited, but is preferably the same as the content exemplified as the content of the polymerization initiator in condition (A).

[0028] (1.3) Condition (C) Under condition (C), the coating film-forming composition contains a polymer and a solvent, the overall weight-average molecular weight of the polymer is 10,000 or more, and the overall density of the solvent at 20°C is 0.80 g / cm³. 3 The temperature is above or above, or the boiling point of the solvent is 80°C or higher. When condition (C) is met, the coating film-forming composition of this disclosure can form a micro-coating film on an electronic substrate. Specifically, when the coating film-forming composition of this disclosure is applied to an electronic substrate by, for example, an inkjet method or a dispenser method, it can be easily ejected or applied, form stable droplets, and avoid bleeding after application to the electronic substrate.

[0029] (1.3.1) Physical properties Under condition (C), the overall weight-average molecular weight (Mw) of the polymer is 10,000 or more, preferably 11,000 or more, more preferably 12,000 or more, and most preferably 13,000 or more. The overall weight-average molecular weight (Mw) of the polymer may also be 1,500,000 or less, 1,000,000 or less, 500,000 or less, etc. The method for measuring the overall weight-average molecular weight (Mw) of the polymer is the same as the measurement method described in the examples. Under condition (C), the total density of the solvent at 20°C is preferably 0.80 g / cm³. 3 The above is preferable, and preferably 0.82 g / cm³ 3 More preferably 0.83 g / cm³ 3 In summary, the most preferred value is 0.85 g / cm³. 3 That concludes the explanation. Furthermore, the total density of the solvent at 20°C is 1.50 g / cm³. 3 Below, 1.30g / cm 3 Below 1.10g / cm 3The following may also be used. The total density of the solvent at 20°C is calculated arithmetically from the mass and volume of the solvent. Under condition (C), the boiling point of the solvent is preferably 85°C or higher, more preferably 90°C or higher, even more preferably 95°C or higher, and most preferably 100°C or higher. The boiling point of the solvent may also be 500°C or lower, 400°C or lower, 300°C or lower, etc. The boiling point of the solvent is determined by catalog values ​​or measurements obtained by gas chromatography distillation (JIS K 2254).

[0030] (1.3.2) Polymers Under condition (C), the coating film-forming composition of this disclosure contains a polymer, from the viewpoint of obtaining stable droplet formation and a micro-coating film with good dimensional accuracy after impact. Examples of polymer types under condition (C) include synthetic resins such as thermoplastic resins, thermosetting resins, and photocurable resins, as well as naturally derived resins such as biopolymers. Examples of thermoplastic resins include polyolefin resins (e.g., polyethylene, polypropylene, polyisobutylene, polystyrene, polyvinyl chloride, etc.), polyolefin waxes (e.g., polyethylene oligomers, polypropylene oligomers, etc.), polysulfide resins, polyvinylidene fluoride resins, polyvinyl fluoride resins, polytetrafluoroethylene resins, acrylic resins, polycarbonate resins, thermoplastic polyester resins, polyamide resins, polyimide resins, ABS (Acrylonitrile Butadiene Styrene) resins, elastomers (e.g., polyolefin elastomers, hydrogenated styrene block copolymers, hydrogenated styrene random copolymers, etc.), super engineering plastics (e.g., polyphenylene sulfide, polyamide-imide, polyethersulfone, polyetheretherketone, etc.), and syndiotactic polystyrene. The thermoplastic resin may also be a copolymer compound composed of two or more comonomers, a graft polymerization compound, or a block polymerization compound synthesized by living radical polymerization or the like. Examples of thermosetting or photocurable resins include unsaturated polyester resins, phenolic resins, urea resins, polyurethane resins, melamine resins, acrylic resins, silicone resins, alkyd resins, and thermosetting polyimides. When the coating film-forming composition contains a thermosetting or photocurable resin, the monomer and initiator before curing may be mixed, the mixture may be immediately filled into a containment space, and the mixture may be cured by heat or light to form the coating film. Among these, polyolefin elastomers, polyvinylidene fluoride, polyethyleneimine, polymethyl methacrylate, or polystyrene are preferred polymers.

[0031] The polymer content is not particularly limited, but is preferably 0.001 to 25 parts by mass, more preferably 0.002 to 23 parts by mass, even more preferably 0.003 to 22.5 parts by mass, and most preferably 0.005 to 22 parts by mass, per 100 parts by mass of the coating film-forming composition. If the polymer content is within the above range, the coating film-forming composition of this disclosure readily forms a uniform coating film, and droplet generation, dispensing, and coating are facilitated.

[0032] (1.3.3) Solvent Under condition (C), the coating film-forming composition contains a solvent. The viscosity of the polymer can be adjusted by including a solvent in the coating film-forming composition. The solvents used in condition (C) are the same as those exemplified as the solvents used in condition (B). Of these, water, alcohols, hydrocarbon compounds, carbonyl compounds, and amide compounds are preferred as solvents in condition (C) in terms of stable droplet formation and good coating film formation after impact. More preferred solvents include water, hydrocarbon compounds, amide compounds, and carbonyl compounds. Particularly preferred solvents in condition (C) are water, glycerol-added water, xylene, methylcyclohexane, cyclohexanone, dimethylformamide, and N-methyl-2-pyrrolidone. These solvents may be used individually or as a mixture of two or more. Under condition (C), the solvent content is not particularly limited. The upper limit of the solvent content is preferably 99 parts by mass or less, more preferably 97 parts by mass or less, and even more preferably 95 parts by mass or less, per 100 parts by mass of the coating film-forming composition. The lower limit of the solvent content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, per 100 parts by mass of the coating film-forming composition.

[0033] (1.4) Physical properties of the coating film-forming composition (1.4.1) Solution viscosity The solution viscosity of the coating film-forming composition of this disclosure, when measured at 20°C using a Type B viscometer, is not particularly limited. The upper limit of the solution viscosity of the coating film-forming composition of this disclosure is preferably 2000 mPa·sec or less, more preferably 1000 mPa·sec or less, even more preferably 500 mPa·sec or less, and most preferably 350 mPa·sec or less. The lower limit of the solution viscosity of the coating film-forming composition of this disclosure is preferably 0.5 mPa·sec or higher, more preferably 1 mPa·sec or higher, even more preferably 5 mPa·sec or higher, and most preferably 10 mPa·sec or higher. If the solution viscosity of the coating film-forming composition of this disclosure is within the above range, the coating film-forming composition of this disclosure can be easily ejected or applied to an electronic substrate by, for example, an inkjet method or a dispenser method, forming more stable droplets and further avoiding bleeding after application to the electronic substrate. The method for measuring the solution viscosity of the coating film-forming composition of this disclosure is the same as that described in the examples.

[0034] (1.4.2) Equation difference (ΔE) The ΔE measured by a color difference system when the coating film-forming composition of this disclosure is formed into a cured film is not particularly limited. The cured film is obtained by spin-coating the coating film-forming composition onto an 18 mm × 18 mm, 0.14 mm thick cover glass to a thickness of approximately 400 μm and then curing it. The upper limit of ΔE is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less. The lower limit of ΔE may be, for example, 0. If ΔE falls within the above range, the resulting micro-coated film will have low transparency and be susceptible to the effects of light absorption. A ΔE of 10 or less means, for example, that the coating film-forming composition of this disclosure does not contain pigments contained in paints used in inkjet methods, etc. The method for measuring ΔE is the same as that described in the examples.

[0035] (1.4.3) Additives The coating film-forming compositions of this disclosure may contain additives such as metals, inorganic materials such as ceramics, carbon materials, and low molecular weight compounds (paraffin, glycerol, etc.). However, it is preferable that the coating film-forming compositions of this disclosure do not contain pigments as additives.

[0036] Examples of inorganic materials include glass fibers, single-crystal silicon, silicon nitride, silicon carbide, and inorganic fillers. Examples of inorganic fillers include amorphous fillers (e.g., calcium carbonate, silica, kaolin, clay, titanium dioxide, barium sulfate, zinc oxide, magnesium oxide, lanthanum oxide, cerium oxide, zirconium oxide, hydrotalcite, aluminum hydroxide, alumina, magnesium hydroxide, etc.), plate-shaped fillers (e.g., talc, mica, montmorillonite, glass flakes, etc.), needle-shaped fillers (e.g., wollastonite, potassium titanate, basic magnesium sulfate, sepiolite, xonotlite, aluminum borate, etc.), conductive fillers (e.g., metal powder, metal flakes, carbon black, carbon nanotubes, etc.), perovskite compounds (e.g., strontium titanate), glass beads, glass powder, apatite, hydroxyapatite, and zeolite. The inorganic fillers may have their surfaces coated with carbon or the like, and may be subjected to silane coupling treatment or the like.

[0037] Examples of carbon materials include carbon fibers, activated carbon, carbon nanotubes, carbon nanohorns, graphene, and graphite.

[0038] The coating film-forming compositions of this disclosure may include synthesized porous materials such as metal-organic frameworks (MOFs). The metal-organic frameworks may also be called porous coordination polymers. For example, the metal-organic frameworks may be Basolite® C300 (manufactured by BASF).

[0039] When the coating film-forming composition of this disclosure contains a small amount of resin as droplets, the conditions for droplet formation are influenced by physical properties such as solution density, boiling point, molecular weight and molecular weight distribution, viscosity, and surface tension, as well as the type of secondary components related to boiling point elevation. Therefore, it is preferable to select these factors in order to obtain the desired liquid properties.

[0040] A specific method for increasing the density or boiling point of the coating film-forming composition of this disclosure is, for example, to increase the density of the solvent, monomer, or polymer used to 1.00 g / cm³. 3 Methods include selecting a substance that is greater than and / or has a boiling point of 100°C or higher, and adding an additive (e.g., glycerol) that is compatible with the solution and increases its density or boiling point.

[0041] The method for forming the coating film composition of this disclosure on the surface of a support is preferable to use a dispenser method for film formation, as it involves uniformly coating a specific film thickness in a minute area. When forming a coating film on an element such as a MEMS, the minute area can be not only a flat surface but also complex shapes with steps, irregularities, and curved surfaces.

[0042] In the present disclosure, it is preferable that the coating film formed after curing is used as a gas sensor-sensitive film. The paint film will be discussed later. The gas sensor-sensitive film may be one that has properties such as being a transformer that changes in mass, volume, conductivity, etc., upon adsorption of a specific gas. The type of gas that the transformer adsorbs depends on the raw materials of the transformer. Examples of the modified bodies include the volume-changing bodies described in International Publication No. 2019-188164 or Japanese Patent Publication No. 2019-174331. Please provide a simple example of a gas sensor and sensing unit.

[0043] When the coating film-forming composition of this disclosure is used to form a coating film, the critical surface tension at the gas-contacting surface of the coating film is not particularly limited. The upper limit of the critical surface tension of the coating film is preferably 36 dynes / cm or less, more preferably 35 dynes / cm or less, and even more preferably 34 dynes / cm or less. The lower limit of the critical surface tension of the coating film is preferably 15 dynes / cm or more. In this disclosure, the critical surface tension of the coating film is measured by the Zismann plot method.

[0044] (1.5) Coating film The coating film of this disclosure is formed by curing the coating film-forming composition of this disclosure.

[0045] The average film thickness of the coating film of this disclosure is not particularly limited, but is preferably 0.5 nm to 50 μm, more preferably 1 nm to 25 μm, and even more preferably 2 nm to 10 μm. If the coating film of this disclosure falls within the above range, it is a more uniform thin film and can fully exhibit its effects as a gas sensor-sensitive film, separation film, or protective film. The method for measuring the average film thickness of the coated film according to this disclosure is the same as that described in the examples.

[0046] The coating film of this disclosure is preferably used as a gas sensor-sensitive film. For gas sensor-sensitive films, please refer to International Publication No. 2019-188164 and Japanese Patent Publication No. 2019-174331.

[0047] (1.6) Gas sensor The gas sensor of this disclosure is a gas sensor including a sensing portion, wherein the coating film of this disclosure is formed on the sensing portion. Examples of gas sensors include stress sensors and mass sensors. Alternatively, the gas sensor may be one of those described in International Publication No. 2019-188164 or Japanese Patent Publication No. 2019-174331.

[0048] In the gas sensor of this disclosure, it is preferable that the length or diameter of one side of the coated film is 10 mm or less. The shape of the coated film is preferably polygonal or circular. Examples of polygons include triangles, squares, rectangles, and pentagons.

[0049] (1.7) Method for manufacturing gas sensors The method for manufacturing the gas sensor of the present disclosure includes the step of forming the coating film of the present disclosure on the sensing portion of the gas sensor. For information on the method for manufacturing the gas sensor disclosed herein, please refer to International Publication No. 2019-188164 and Japanese Patent Publication No. 2019-174331.

[0050] In the method for manufacturing a gas sensor according to the present disclosure, it is preferable to apply a coating film to a minute area having a side length or diameter of 10 mm or less.

[0051] In the method for manufacturing a gas sensor according to the present disclosure, it is preferable to apply a coating film to the minute area by an inkjet method or a dispenser method. [Examples]

[0052] The present disclosure will be described below with reference to examples, but the present disclosure is not limited in any way by these examples.

[0053] <Preparation of the composition for forming the coating film> Monomer solutions A to F and polymer solutions A to G were prepared as compositions for forming coated films. For monomer solutions A to F, 1 part by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Ciba® IRGACURE® 819) was added to 100 parts by weight of each monomer solution.

[0054] Monomer solution A: Dimethylol tricyclodecane diacrylate ("Light Acrylate DCP-A", Kyoeisha Chemical Co., Ltd.) monomer solution Monomer solution B: 3-(Acryloyloxy)-2-Hydroxypropyl Methacrylate ("Light Ester G-201P", Kyoeisha Chemical Co., Ltd.) monomer solution Monomer solution C: Mono(2-acryloyloxyethyl) succinate ("Light Acrylate HOA-MS(N)", Kyoeisha Chemical Co., Ltd.) monomer solution Monomer solution D: Methyl methacrylate (MMA, Sigma-Aldrich) monomer solution Monomer solution E: Methylcyclohexane (Sigma-Aldrich) solvent Monomer solution F: Water (distilled water)

[0055] Polymer solution A: 3% by mass toluene solution of polyolefin elastomer (polymerized by the method described in International Publication No. 2004 / 087775, weight-average molecular weight 150,000) Polymer solution B: 10% by mass cyclohexanone solution of polyvinylidene fluoride (PVDF, Sigma-Aldrich, weight-average molecular weight 180,000) Polymer solution C: 25% by mass aqueous solution of polyethyleneimine (PEI, Fujifilm Wako Pure Chemical Industries, Ltd., weight-average molecular weight 70,000) Polymer solution D: 25% by mass (N-methyl-2-pyrrolidone) NMP solution of polymethyl methacrylate (PMMA, Fujifilm Wako Pure Chemical Industries, Ltd., weight-average molecular weight 15,000) Polymer solution E: 1 mass% N,N-dimethylformamide (DMF) solution of polystyrene (PS, Sigma-Aldrich, weight average molecular weight 35,000) Polymer solution F: 10 mass% hexane solution of polyvinyl chloride (PVC, Sigma-Aldrich, weight average molecular weight 43,000) Polymer solution G: 5 mass% xylene solution of polyolefin (polymerized by the method described in JP 2003-147010 A, weight average molecular weight 1,200)

[0056] <Measurement conditions etc. for each physical property of the composition for forming a coating film> The measurement conditions etc. for each physical property of the composition for forming a coating film are as follows.

[0057] For the molecular weight, boiling point, and density of the monomer and solvent of the composition for forming a coating film, catalog values were used.

[0058] The solution viscosity of the composition for forming a coating film was measured at 20 °C and a shear rate of 2.0 N / sec using a B-type viscometer (cone plate viscometer CPA-52Z, manufactured by Eiko Seiki Co., Ltd.).

[0059] The average film thickness of the coating film is the average value of the measured values obtained by measuring three points using a white light interference type non-contact film thickness measuring device (FILMETRICS(R)).

[0060] The weight average molecular weight (Mw) of the polymer contained in the composition for forming a coating film was measured by the following method. The weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC) under the following conditions. <GPC conditions> Apparatus: Gel permeation chromatograph Alliance GPC2000 type (manufactured by Waters) Solvent: o-dichlorobenzene Column: TSKgel column (manufactured by Tosoh Corporation) × 4 Flow rate: 1.0 mL / min Sample: 0.15 mg / mL o-dichlorobenzene solution Temperature: 140 °C Molecular weight conversion: PE conversion / General calibration method

[0061] For the general calibration calculation, the coefficients of the Mark-Houwink viscosity equation shown below were used. Coefficient for polystyrene (PS): KPS = 1.38 × 10 -4 aPS=0.70 Coefficient for polyethylene (PE): KPE = 5.06 × 10 -4 aPE=0.70

[0062] A larger molecular weight results in a greater solvation effect, leading to a larger boiling point elevation even with a low solvent boiling point, and reducing the impact of volatilization. Furthermore, a broad molecular weight distribution can lead to a greater viscosity increase even at low polymer concentrations, potentially causing the discharge conditions to fall outside the appropriate range.

[0063] The hue of the coating film-forming composition was measured as follows: The hue of the coating film, which was spin-coated to a thickness of approximately 400 μm on an 18 mm x 18 mm, 0.14 mm thick cover glass (Matsunami Cover Glass No. 1), was measured using the color difference (ΔE) in reflection mode with a Colour Cute i model CC-i (manufactured by Suga Test Instruments Co., Ltd.).

[0064] <Example 1> As a dispenser-type coating device, we used the NTN Corporation's desktop fine pasting system NRS-3018 and high-repetition coating needle HR-100 (coating needle diameter 100 μm). Monomer solution A was used as the composition for forming the coated film. As an example of an electronic substrate for evaluation, a cantilever (NPX1CTP004, Hitachi High-Tech Corporation, or OMCL-AC240-TN-C3, Olympus Corporation) was used. A coating film-forming composition was applied to the stage portion of the cantilever, and LED irradiation was performed using "Translux® 2Wave" (manufactured by Kulzer Japan Co., Ltd.) to form a micro-coated film (diameter 100 μm, thickness approximately 100 nm).

[0065] <Evaluation of coating film formation of coating film-forming compositions (dipenser method)> When a coating film-forming composition was applied to an electronic substrate using a dispenser-type coating device, the appearance of the applied coating film-forming composition was visually inspected. Based on the appearance of the applied coating film-forming composition, whether or not a micro-coating film could be formed was evaluated according to the following criteria. An acceptable evaluation is "A". A: A droplet was dispensed and a coating film was formed without evaporation. B: Either the droplet could not be dispensed, or although the droplet was dispensed, it evaporated and did not land as a droplet, thus failing to form a coating film.

[0066] <Evaluation of coating film formation of coating film-forming compositions (inkjet method)> When a coating film-forming composition was applied to an electronic substrate using a Dimatix material printer (FUJIFILM Dimatix "DMP-2831") (discharge conditions: 26V, 5kHz), the appearance of the applied coating film-forming composition was visually inspected. Based on the appearance of the applied coating film-forming composition, whether or not a micro-coating film was formed was evaluated according to the following criteria. An acceptable evaluation is "A". A: A droplet was dispensed and a coating film was formed without evaporation. B: Either the droplet could not be dispensed, or although the droplet was dispensed, it evaporated and did not land as a droplet, thus failing to form a coating film.

[0067] The evaluation results are shown in Table 1.

[0068] <Examples 2-8, Comparative Examples 1-5> The results were evaluated in the same manner as in Example 1, except that the monomer solution A was replaced with the monomer solution or polymer solution listed in Table 2 as the composition for forming the coating film. The evaluation results are shown in Tables 1 and 2.

[0069] [Table 1]

[0070] [Table 2]

[0071] In Table 1, "DTA" represents dimethylol tricyclodecanediaacrylate, "AHM" represents 3-(acryloyloxy)-2-hydroxypropyl methacrylate, "MAS" represents mono(2-acryloyloxyethyl) succinate, "MMA" represents methyl methacrylate, and "MCH" represents methylcyclohexane. In Table 2, "PO elastmer" refers to polyolefin elastomer, "PVDF" refers to polyvinylidene fluoride, "PEI" refers to polyethyleneimine, "PMMA" refers to polymethyl methacrylate, "NMP" refers to N-methyl-2-pyrrolidone, "DMF" refers to N,N-dimethylformamide, and "flexible PVC" refers to polyvinyl chloride.

[0072] As shown in the results in Table 1, the coating film-forming compositions of Examples 1 to 3, whose monomer molecular weight and boiling point or density satisfy claim 1, enabled the formation of a micro-coated film on an electronic substrate using a dispenser method. The coating film-forming compositions of Comparative Examples 1 to 3, whose monomer molecular weights and boiling points or densities did not meet the claims, were unable to form micro-coated films on electronic substrates using the dispenser method.

[0073] As shown in the results in Table 2, the coating film-forming compositions of Examples 4 to 8, in which the molecular weight of the polymer and the boiling point or density of the solvent satisfy claim 1, enabled the formation of a micro-coated film on an electronic substrate using the dispenser method. Comparative Examples 4 to 5, whose polymer molecular weight and solvent boiling point or density did not meet the claims, were unable to form micro-coated films on electronic substrates using the dispenser method.

[0074] From these findings, it was found that a coating film-forming composition can form a micro-coating film on an electronic substrate if it satisfies any one of the conditions (A) to (C) specified in claim 1.

Claims

1. Containing monomers or polymers, Satisfying at least one of the following conditions (A) to (C): A coating film forming composition wherein the coating film, when cured and formed into a coating film, is used as a gas sensor-sensitive film. (A) The coating film-forming composition contains the monomer and polymerization initiator, and does not contain a solvent. The total molecular weight of the monomer is 50 or more, The overall density of the monomer at 20°C is 1.00 g / cm³. ３ The boiling point of the monomer must be 105°C or higher. (B) The coating film-forming composition comprises the monomer, solvent and polymerization initiator, The total molecular weight of the monomer and solvent is 50 or more, The total density of the monomer and solvent at 20°C is 1.00 g / cm³. ３ The boiling point of the monomer and solvent must be 105°C or higher. (C) The coating film-forming composition comprises the polymer and the solvent, The polymer consists of one selected from the group consisting of polyolefin elastomer, polyvinylidene fluoride, polyethyleneimine, polymethyl methacrylate, and polystyrene. The overall weight-average molecular weight of the polymer is 10,000 or more, The total density of the solvent at 20°C is 0.80 g / cm³. ３ The temperature must be above or equal to that of the solvent, or the boiling point of the solvent must be 80°C or higher.

2. The coating film-forming composition according to claim 1, wherein the solution viscosity at 20°C, as measured by a B-type viscometer, is 0.5 mPa·sec to 2000 mPa·sec.

3. The coating film-forming composition according to claim 1 or claim 2, wherein the polymer content under the conditions of (C) is 0.001 parts by mass to 25 parts by mass per 100 parts by mass of the coating film-forming composition.

4. A coating film forming composition according to any one of claims 1 to 3, wherein the ΔE measured by a color difference system when formed into a cured film is 10 or less.

5. A coating film-forming composition according to any one of claims 1 to 4, which is applied to a minute region having a side length or diameter of 10 mm or less.

6. A coating film formed by curing the coating film-forming composition according to any one of claims 1 to 5.

7. The coated film according to claim 6, wherein the average film thickness is 0.5 nm to 50 μm.

8. A coating film according to claim 6 or claim 7, which is used as a gas sensor-sensitive film.

9. A gas sensor including a sensing section, wherein a coating film according to any one of claims 6 to 8 is formed on the sensing section.

10. The gas sensor according to claim 9, wherein the length or diameter of one side of the coating film is 10 mm or less.

11. A method for manufacturing a gas sensor, comprising the step of forming a coating film according to any one of claims 6 to 8 on the sensing portion of a gas sensor.

12. A method for manufacturing a gas sensor according to claim 11, wherein the coating film is applied to a minute region having a side length or diameter of 10 mm or less.

13. A method for manufacturing a gas sensor according to claim 11 or 12, wherein the coating film is applied to a minute area having a side length or diameter of 10 mm or less by an inkjet method or a dispenser method.

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