Insulating composition

Abstract

Provided is an insulating composition capable of improving coverage properties.　An insulating composition contains (A) a thermosetting resin, (B) a curing agent and (C) a fluidity control agent, and is characterized in that a viscosity VR120 obtained by measuring solid content in the insulating composition at 120°C and 100 rpm using a rheometer is 28 mPa·s or more. The insulating composition preferably further contains a solvent (D).　

Description

Insulating composition

[0001] The present invention relates to an insulating composition that can improve coverage.

[0002] Electronic components mounted on a substrate are coated with a composition for forming an insulating film to impart insulating properties to the metal parts. Materials for the insulating composition that forms the insulating film of electronic components include organic substances including epoxy resins and inorganic substances including ceramics. Methods for applying the insulating composition to an object include screen printing, electrodeposition coating, spray coating, etc. when the insulating composition is a liquid. Methods for applying the insulating composition to an object include physical vapor deposition (PVD), thermal spraying, etc. when the insulating composition is a powder.

[0003] Cited Document 1 discloses a curable composition for spray coating that contains 100 parts by mass of a polymer having a hydrolyzable silyl group, a plasticizer containing a polyalkylene oxide polymer, 30 to 500 parts by mass of a filler having an average particle size of 0.5 to 4 μm, and a catalyst, and that has a viscosity of 150 Pa s or less at 100 rpm at 25°C and a Ti value (viscosity at 1 rpm at 25°C / viscosity at 100 rpm at 25°C) of 10 to 50.

[0004] Japanese Patent Application Laid-Open No. 2023-7423

[0005] The curable composition for spray coating disclosed in Patent Document 1 is required to prevent clogging of the spray nozzle during spray coating. For example, a liquid insulating composition containing an organic substance that is applied by spraying can reduce costs such as material costs and equipment costs and achieve high productivity compared to an insulating composition containing an inorganic substance in powder form. On the other hand, the chemical solution used for spray coating, etc., must be adjusted to a low viscosity due to the application method using a spray. When heated, etc., to cure the composition, the applied portion may flow, exposing the edges or sides of the object to be coated, and the coating film may have low coverage.

[0006] Therefore, an object of the present invention is to provide an insulating composition that can improve coverage.

[0007] The means for solving the above problems are as follows, and the present invention includes the following aspects.

[0008] [1] An insulating composition comprising (A) a thermosetting resin, (B) a curing agent, and (C) a flow control agent, wherein the viscosity V of a solid of the insulating composition measured with a rheometer under conditions of 120 ° C. and 100 rpm is Ｒ１２０ [2] The insulating composition further contains (D) a solvent, and the insulating composition has a viscosity V measured with a Brookfield viscometer at 25°C and 100 rpm. Ｂ２５（１００） [3] The insulating composition according to [1], wherein the viscosity V measured with a Brookfield viscometer at 25°C and 100 rpm is 600 mPa·s or less. Ｂ２５（１００） Viscosity V measured with a Brookfield viscometer at 25°C and 10 rpm Ｂ２５（１０） The ratio (V Ｂ２５（１０） / V Ｂ２５（１００） [4] The insulating composition according to any one of [1] to [3], wherein the insulating composition is applied to a coating film having a thickness of 10 μm after curing, and the resulting cured film has an insulation resistance of 50 MΩ or more when a voltage of 100 V is applied to the cured film. [5] The insulating composition according to any one of [1] to [4], wherein the insulating composition is applied to a copper plate, and the resulting coating film is cured, and the resulting cured film has a surface that exhibits a cross-cut test result of 3B or more according to ASTM D3359-97. [6] The insulating composition according to any one of [1] to [4], wherein the viscosity V of the solid content of the insulating composition measured with a rheometer at 25°C and 100 rpm is 3.0 or more. Ｒ２５ Viscosity V measured with a rheometer at 120 ° C. and 100 rpm Ｒ１２０ The ratio (V Ｒ１２０ / V Ｒ２５x 100) is 10% or more. [7] The insulating composition according to any of [1] to [6] above, wherein the (A) thermosetting resin includes an epoxy resin. [8] The insulating composition according to any of [1] to [7] above, wherein the (C) flowability control agent includes at least one selected from the group consisting of a (C1) thermoplastic resin, (C2) inorganic particles, and (C3) nanofibers. [9] The insulating composition according to any of [1] to [8] above, wherein the (C) flowability control agent includes a (C1) thermoplastic resin having a weight-average molecular weight of 10,000 or more and 100,000 or less.

[10] The insulating composition according to any of [1] to [9] above, wherein the (C) flowability control agent includes a (C1) thermoplastic resin having a glass transition temperature (Tg) of 160°C or less.

[11] The insulating composition according to any one of [1] to

[10] , wherein the (C) flowability control agent includes (C2) inorganic particles having an average particle size of 1 μm or less.

[12] The insulating composition according to any one of [1] to

[11] , wherein the (C) flowability control agent includes (C3) nanofibers, the (C3) nanofibers being cellulose fibers.

[13] The insulating composition according to any one of [1] to

[12] , wherein the (C) flowability control agent is contained in an amount of 0.1 mass % to 20 mass % of the total amount.

[14] The insulating composition according to any one of [2] or [3] to

[13] , which cites [2], wherein the (D) solvent includes (D1) solvent having a boiling point of less than 100° C. and (D2) solvent having a boiling point of 100° C. or more.

[15] The insulating composition according to any one of [1] to

[14] , wherein the insulating composition is applied to a metal plate to form a coating film having a thickness of 10 μm after curing, and the cured film is cured to form a composite of the metal plate, wherein the ratio of the thermal conductivity of the cured film to the thermal conductivity of the metal plate (thermal conductivity of the composite / electrical conductivity of the metal plate × 100) is 60% or more.

[16] The insulating composition according to any one of [1] to

[15] , which is for spray application.

[17] The insulating composition according to any one of [1] to

[15] , which is for coating.

[0009] According to the present invention, an insulating composition capable of improving coverage is provided.

[0010] 1 is a graph showing the relationship between the temperature and viscosity of the solid content of each insulating composition used in each insulating composition of Examples and Comparative Examples.

[0011] The following description is based on the insulating composition according to the present disclosure. The following embodiments are merely examples for embodying the technical concept of the present invention, and the present invention is not limited to the insulating composition described below. In this specification, "to" means the upper and lower limits of the numerical values ​​or symbols containing numerical values ​​described before and after it, and represents the range from above to below. Note that the "insulating composition" in this invention refers to a composition appropriately containing (A) a thermosetting resin, (B) a curing agent, (C) a flowability control agent, and (D) other optional components such as a solvent, as described below. Furthermore, the "solid content of the insulating composition" in this invention refers to the components in the composition in a state in which volatile substances such as solvents have been removed from the insulating composition described above. The solid content includes liquid, starch syrup, and wax-like substances at room temperature around 25°C, and does not necessarily mean solid.

[0012] The insulating composition is an insulating composition containing (A) a thermosetting resin, (B) a curing agent, and (C) a flowability control agent, and the insulating composition has a viscosity V of 1000 kJ / 2000 kcal / 2000 rpm measured by a rheometer under conditions of 120°C and 100 rpm. Ｒ１２０ is 28 mPa·s or more.

[0013] The insulating composition preferably further contains a solvent (D). The insulating composition further contains a solvent (D), and has a viscosity V measured with a Brookfield viscometer at 25° C. and 100 rpm. Ｂ２５（１００） Furthermore, the insulating composition containing the solvent (D) preferably has the above-mentioned viscosity V Ｂ２５（１００） If the viscosity is 600 mPa s or less, even when the flowability control agent (C) is contained, the insulating composition can be evenly applied to the target portion of the object to be coated without clogging the nozzle when screen printing or spray coating is performed, particularly when spray coating is performed.

[0014] The insulating composition had a viscosity V measured at 25°C and 100 rpm using a Brookfield viscometer. Ｂ２５（１００）The insulating composition has a viscosity V measured with a Brookfield type viscometer at 25°C and 100 rpm, preferably 500 mPa·s or less, more preferably 400 mPa·s or less, even more preferably 300 mPa·s or less, and may be 200 mPa·s or less, 100 mPa·s or less, or even 50 mPa·s or less. Ｂ２５（１００） The lower limit of the viscosity is not particularly limited, but may be 1.0 mPa·s or 2.0 mPa·s or more. As the B-type viscometer, for example, a Brookfield rotational viscometer LVDV-II Pro can be used.

[0015] The insulating composition has a viscosity V when the solid content of the insulating composition is heated at 120°C, that is, a viscosity V when the solid content is measured with a rheometer under the conditions of 120°C and 100 rpm. Ｒ１２０ The solid content of the insulating composition has a viscosity V Ｒ１２０ If the viscosity V of the insulating composition is 28 mPa·s or more, the coating film has good coverage on the target object, and even if a volatile substance such as the (D) solvent volatilizes due to the temperature during drying, the coating film will be maintained without peeling or flowing off from the applied coating film even on the side surfaces and edges including corners of the metal part of the target object, and a cured film can be formed by curing the coating film with good coverage. Ｒ１２０ is the viscosity value measured by a rheometer at 120°C and 100 rpm for the components (solid content) of the insulating composition in a state where volatile substances such as solvents have been removed from the insulating composition.

[0016] The insulating composition has a viscosity V when the solid content of the insulating composition is measured using a rheometer under conditions of 120°C and 100 rpm. Ｒ１２０ If the viscosity is less than 28 mPa·s, after the insulating composition is applied to the object, the applied insulating composition may run off during drying before curing, which may result in the side surfaces and edges, including corners, of the object being easily exposed, resulting in a decrease in coverage. Ｒ１２０The viscosity V of the solid content of the insulating composition is more preferably 30 mPa·s or more, further preferably 40 mPa·s or more, and may be 100 mPa·s or more. Ｒ１２０ The upper limit of the viscosity V of the solid content of the insulating composition is preferably 500 mPa·s or less, and more preferably 400 mPa·s or less. Ｒ１２０ If the viscosity exceeds 500 mPa·s, when the insulating composition is applied to an object by, for example, spraying, it may not be leveled and the coating film may become non-uniform. ＴＭ MARS ＴＭ A rheometer (manufactured by Thermo Scientific) with a parallel cone having a diameter of 35 mm (35 mmφ) can be used.

[0017] The insulating composition had a viscosity V measured at 25°C and 10 rpm using a Brookfield viscometer. Ｂ２５（１０） and viscosity V at 100 rpm Ｂ２５（１００） The ratio (V Ｂ２５（１０） / V Ｂ２５（１００） It is preferable that the thixotropy index TI (V) of the insulating composition is 3.0 or less. If the TI of the insulating composition measured with a Brookfield viscometer under the above-mentioned conditions is 3.0 or less, the insulating composition is endowed with thixotropy, improving the applicability to the object, preventing the applied coating from flowing and exposing the side surfaces and edges, including corners, of the object, and improving coverage. The insulating composition has a thixotropy index TI (V Ｂ２５（１０） / V Ｂ２５（１００） In order to impart thixotropy that improves application properties to the insulating composition, the thixotropy index TI may be 0.1 or more, 0.3 or more, 0.5 or more, or 0.7 or more.

[0018] The insulating composition has a viscosity V measured by a rheometer at 25°C and 100 rpm. Ｒ２５ Viscosity V measured with a rheometer at 120 ° C. and 100 rpm Ｒ１２０ The ratio (V Ｒ１２０ / V Ｒ２５× 100) (hereinafter also referred to as "viscosity change rate") is preferably 10% or more, more preferably 11% or more, may be 15% or more, or may be 20% or more. Ｒ１２０ / V Ｒ２５ If the viscosity change rate (V × 100) is 10% or more, the coating film applied to the object will not run off from the side or end of the object even when volatile substances such as (D) solvent have evaporated from the coating film applied to the object during drying before curing, and the coating film will have good coverage and can be formed on the target part of the object. Ｒ１２０ / V Ｒ２５ The upper limit of the ratio (%) is not particularly set, but may be, for example, 80% or less, 50% or less, or 40% or less.

[0019] The insulating composition preferably has an insulation resistance value of 50 MΩ or more when a voltage of 100 V is applied to a cured film obtained by curing a coating film applied to a target object so that the coating film has a thickness of 10 μm after curing. The insulating composition has good coating coverage on the target object, and a cured film is formed by curing a coating film applied with the insulating composition without exposing the side surfaces and edges of the target object. If the insulating composition has an insulation resistance value of 50 MΩ or more when a voltage of 100 V is applied to a cured film obtained by curing a coating film applied to a target object so that the coating film has a thickness of 10 μm or more after curing, the cured film can serve as an excellent insulating film for electronic components. The cured film can be used as a highly safe insulating film that imparts insulation to specific portions of leads on which chips are arranged or metal plates that function as heat sinks in electronic components such as vertical cavity surface emitting lasers (VCSELs). The insulating composition is preferably a cured film obtained by applying a coating to a thickness of 10 μm after curing and curing the coating to have an insulation resistance value of 55 MΩ or more when a voltage of 100 V is applied, more preferably 60 MΩ or more, even more preferably 62 MΩ or more, and particularly preferably 65 MΩ or more.

[0020] When the insulating composition is applied to the surface of a copper plate and cured, the surface of the cured film obtained by curing the coating film is subjected to a cross-cut test according to ASTM D3359-97 Standard Method B, preferably the result is 3B or higher, more preferably 4B or higher, and even more preferably 5B or higher. A cross-cut test result of 3B or higher for a cured film obtained by curing a coating film applied to the surface of the insulating composition indicates good adhesion between the cured film and the copper plate. The cross-cut test involves cutting a sample surface of a cured film formed on a copper plate into a grid pattern at regular intervals, applying and peeling off adhesive tape, and then counting the number of lattice units where no flakes are generated. According to ASTM D3359-97 Standard (Method B), the surface of the lattice units where no flakes are generated is evaluated into five grades (0B to 5B) based on the percentage of the area of ​​the lattice units where no flakes are generated relative to the total area of ​​the lattice units, with the higher grade indicating better adhesion between the copper plate and the cured film. The percentage of the area of ​​lattice units where no flakes occurred is as follows: 5B, no lattice units peeled off, and the peeled area relative to the total area of ​​lattice units is 0%; 4B, the peeled area relative to the total area of ​​lattice units is 5% or less (≦5%); 3B, the peeled area relative to the total area of ​​lattice units is more than 5% but not more than 15%; 2B, the peeled area relative to the total area of ​​lattice units is more than 15% but not more than 35%; 1B, the peeled area relative to the total area of ​​lattice units is more than 35% but not more than 65%; and 0B, the peeled area relative to the total area of ​​lattice units is more than 65%.

[0021] The insulating composition is formed by applying the insulating composition to a metal plate to form a coating film having a thickness of 10 μm after curing, and curing the coating film. The ratio of the thermal conductivity of the composite of the insulating composition and the metal plate to the thermal conductivity of the metal plate (thermal conductivity of the composite / thermal conductivity of the metal plate × 100) is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. If the ratio of the thermal conductivity of the composite of the cured film and the metal plate to the thermal conductivity of the metal plate is 60% or more, a cured film having excellent insulating properties as an insulating film is formed while maintaining high thermal conductivity without significantly reducing the thermal conductivity of the metal plate. The metal plate may be any known metal plate, such as a copper plate or an aluminum substrate. In this specification, the ratio of the thermal conductivity of the composite to the thermal conductivity of the metal plate (thermal conductivity of the composite / thermal conductivity of the metal plate × 100) is also referred to as the thermal conductivity conversion ratio.

[0022] The thermosetting resin (A) contained in the insulating composition cures the coating film and preferably contains an epoxy resin. The thermosetting resin (A) may contain an acrylic resin. The epoxy resin is preferably liquid at room temperature, but may also be solid at room temperature. An epoxy resin that is solid at room temperature can be used as a liquid epoxy resin or diluted with a solvent or diluent to form a liquid. The epoxy resin refers to one having at least one epoxy group or glycidyl group in its molecule. An epoxy resin that is liquid at room temperature may be used, or may be solid at room temperature. An epoxy resin that is solid at room temperature may be used as a liquid by diluting it with a liquid epoxy resin. The epoxy resin preferably has a weight-average molecular weight in the range of 180 to 6,000, and may also be in the range of 200 to 6,000. In this specification, the weight-average molecular weight refers to a value obtained by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene. Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins and derivatives thereof (e.g., alkylene oxide adducts), hydrogenated bisphenol A type epoxy resins, hydrogenated bisphenol F type epoxy resins, brominated bisphenol A type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, alkylphenol type epoxy resins, glycidyl ether type epoxy resins such as alkyl glycidyl ethers having 6 to 36 carbon atoms, alkylphenyl glycidyl ethers, alkenyl glycidyl ethers, alkynyl glycidyl ethers, and phenyl glycidyl ethers, glycidyl ester type epoxy resins such as alkyl glycidyl esters, alkenyl glycidyl esters, and phenyl glycidyl esters having 6 to 36 carbon atoms, silicone epoxy resins, etc. These epoxy resins may be used alone or in combination of two or more.

[0023] The acrylic resin is preferably a (meth)acrylic resin, which refers to a compound having a (meth)acryloyl group in the molecule. Examples of the (meth)acrylic resin include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isoamyl (meth)acrylate, isostearyl (meth)acrylate, and behenyl (meth)acrylate. Examples of the acrylic resin include methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, other alkyl (meth)acrylates, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, etc. One of these acrylic resins may be used alone, or two or more may be used in combination.

[0024] Specific examples of the epoxy resin contained in the (A) thermosetting resin include commercially available products such as a mixture of bisphenol F epoxy resin and bisphenol A epoxy resin (EXA-835LV, manufactured by DIC Corporation), an alkylphenol epoxy resin (EXA-820D, manufactured by DIC Corporation), and a naphthalene epoxy resin (4032D, manufactured by DIC Corporation).

[0025] The (B) curing agent contained in the insulating composition is used to cure the thermosetting resin. The (B) curing agent in the present invention may also contain a curing accelerator. Examples of the (B) curing agent include amine-based curing agents, imidazole-based curing agents, acid anhydride-based curing agents, carboxylic acid dihydrazide curing agents, and phenol-based curing agents. A single curing agent may be used alone, or two or more may be used in combination. Two or more (B) curing agents may be used in combination, with one being used as the (B1) curing agent and the other one or more being used as (B2) curing accelerators. To improve coverage, it is preferable to use an amine-based curing agent, imidazole-based curing agent, or acid anhydride-based curing agent, which has a relatively fast curing rate. A phenol-based curing agent may also be used to adjust the curing rate.

[0026] Examples of the amine curing agent include chain aliphatic amines, cyclic aliphatic amines, aliphatic aromatic amines, aromatic amines, etc. For example, an example of the aliphatic aromatic amine is 4,4'-diamino-3,3'-diethyldiphenylmethane.

[0027] Examples of imidazole curing agents include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole.

[0028] Examples of acid anhydrides include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexenetetracarboxylic dianhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, ethylene glycol bisanhydrotrimellitate, glycerin bis(anhydrotrimellitate) monoacetate, dodecenyl succinic anhydride, aliphatic dibasic acid polyanhydrides, chlorendic anhydride, methylbutenyltetrahydrophthalic anhydride, alkylated tetrahydrophthalic anhydride, methylhimic anhydride, succinic anhydride substituted with an alkenyl group, and glutaric anhydride.

[0029] Examples of the carboxylic acid dihydrazide curing agent include adipic acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, and dodecanoic acid dihydrazide.

[0030] Examples of phenol-based curing agents include phenol novolac and cresol novolac.

[0031] Specific examples of the (B) curing agent include commercially available products such as 4,4'-diamino-3,3'-diethyldiphenylmethane (KAYAHARD HDAA, manufactured by Nippon Kayaku Co., Ltd.), amine adduct curing agent (PN-40J, manufactured by Ajinomoto Fine-Techno Co., Ltd.), 2-ethyl-4-methylimidazole (2E4MZ, manufactured by Shikoku Chemicals Corporation), microencapsulated imidazole compound curing agent (HX3722, HX3742, HX3932, HX3942HP, manufactured by Asahi Kasei E-materials Corporation), acid anhydride (grades: YH306, YH307, manufactured by Mitsubishi Chemical Corporation), adipic acid dihydrazide (ADH, manufactured by Nippon Finechem Co., Ltd.), etc. An amine-based curing agent may be used as the (B1) curing agent, and 2-ethyl-4-methylimidazole may be used as the (B2) curing accelerator.

[0032] The (C) flow control agent contained in the insulating composition preferably contains at least one selected from the group consisting of (C1) thermoplastic resin, (C2) inorganic particles, and (C3) nanofibers. The (C) flow control agent may be a combination of at least two or more selected from the group consisting of (C1) thermoplastic resin, (C2) inorganic particles, and (C3) nanofibers. By including the (C) flow control agent in the insulating composition, even if volatile substances such as (D) solvent volatilize due to the drying temperature, the applied coating film does not peel off or run off from the sides and edges, including corners, of the metal part of the target object, thereby improving the coverage of the coating film and the cured film formed by curing the coating film on the target object. Note that, for the purpose of improving the coverage of the coating film, known agents other than the (C1) thermoplastic resin, (C2) inorganic particles, and (C3) nanofibers described above can be used as the (C) flow control agent. Examples include pregelling agents containing organic fine particles and viscoelasticity modifiers containing specific polymer components.

[0033] When the (C) flow control agent contains a (C1) thermoplastic resin, the (C1) thermoplastic resin preferably contains a thermoplastic resin having a weight-average molecular weight of 10,000 to 100,000. When the (C1) flow control agent contains a (C1) thermoplastic resin having a weight-average molecular weight of 10,000 to 100,000, the coating film can achieve good coverage on the target object even if volatile substances such as the (D) solvent volatilize due to the drying temperature. When the (C) flow control agent is a (C1) thermoplastic resin, the (C1) thermoplastic resin may contain a thermoplastic resin having a weight-average molecular weight of 20,000 to 80,000 or a thermoplastic resin having a weight-average molecular weight of 25,000 to 70,000. The weight-average molecular weight can be measured by gel permeation chromatography (GPC).

[0034] When the (C) flowability control agent contains the (C1) thermoplastic resin, the (C1) thermoplastic resin preferably has a glass transition point (Tg) of 160° C. or lower, more preferably 50 to 155° C., and particularly preferably 80 to 120° C. When the (C1) thermoplastic resin used as the flowability control agent has a glass transition point (Tg) within the above range, the coating film made of the insulating composition can maintain its coverage on the target object even if volatile substances such as the (D) solvent volatilize during the coating film drying process.

[0035] When the flow control agent (C) contains a thermoplastic resin (C1), the thermoplastic resin (C1) preferably contains a phenoxy resin, which is a polymer of bisphenol A and epichlorohydrin, and examples of phenoxy resins that can be used include PKHB, PKHC, PKHH, PKHJ, and PKEF, manufactured by Gabriel Phenoxies.

[0036] When the (C) flowability control agent contains (C2) inorganic particles, the (C2) inorganic particles are preferably at least one selected from the group consisting of glass, silicon dioxide, aluminum oxide, titanium oxide, boron nitride, and silicon nitride. The (C) flowability control agent preferably contains (C2) inorganic particles having an average particle size of 1 μm or less. The (C2) inorganic particles preferably have an average particle size of less than 1 μm, more preferably in the range of 5 nm to 900 nm, and particularly preferably in the range of 8 nm to 500 nm. The (C2) inorganic particles may be, for example, at least one type of nanoparticle selected from the group consisting of silica nanoparticles, alumina nanoparticles, titanium oxide nanoparticles, boron nitride nanoparticles, and silicon nitride nanoparticles. When the (C2) inorganic particles are nanoparticles, the average particle size can be measured using a dynamic light scattering Nanotrac particle size analyzer. By including (C2) inorganic particles having an average particle size of 1 μm or less, the (C) flowability control agent can impart thixotropy. When the insulating composition contains (C2) inorganic particles having an average particle size of 1 μm or less, the viscosity when heated at 120° C., that is, the viscosity V when the solid content of the insulating composition is measured with a rheometer under the conditions of 120° C. and 100 rpm, is Ｒ１２０From the viewpoint of further improving the above, it is more preferable to use a (C) flowability control agent different from the (C2) inorganic particles in combination with the (C2) inorganic particles.

[0037] The (C2) inorganic particles may be used in a mixture or dispersion of inorganic particles mixed with other components, such as resins. Examples of the resin contained in the mixture or dispersion include thermosetting resins, photocurable resins, and thermoplastic resins. Examples of thermosetting resins include epoxy resins and acrylic resins, and examples of thermoplastic resins include phenoxy resins. Examples of the (C2) inorganic particles include silica nanoparticles with a particle size of 10 nm (YA010C, YA010C-JPGZ, manufactured by Admatechs Co., Ltd.), silica nanoparticles with a particle size of 50 nm (YA050C, manufactured by Admatechs Co., Ltd.), and silica nanoparticles with a particle size of 100 nm (YC100C, manufactured by Admatechs Co., Ltd.).

[0038] When the (C) flowability control agent contains (C3) nanofibers, the (C3) nanofibers are preferably cellulose fibers. The nanofibers preferably contain cellulose nanofibers (hereinafter also referred to as "CNFs") whose size has been reduced to the nanometer level. The cellulose fibers preferably have an average fiber diameter of 0.1 nm or more and preferably 50 nm or less. The average fiber length of the cellulose fibers is preferably 50 nm or more and preferably 1,000 nm or less. The average aspect ratio (average fiber length / average fiber diameter) of the cellulose fibers is preferably 1 to 150, more preferably 5 to 100, and even more preferably 10 to 50. The average fiber diameter, average fiber length, and average aspect ratio of the cellulose fibers may be catalog values. The CNF may be nanofibers in a mixture or dispersion in which the nanofibers are mixed with components other than nanofibers, such as a resin. Examples of the resin contained in the mixture or dispersion include a thermosetting resin, a photocurable resin, and a thermoplastic resin. Examples of thermosetting resins include epoxy resins and acrylic resins, while examples of thermoplastic resins include phenoxy resins. (C3) Nanofibers may be prepared by pre-mixing liquid epoxy resin and nanofibers (CNF) to form a dispersion or mixture, which is then added to the insulating composition. (C3) Nanofibers may be dry CNF or commercially available products. Examples of commercially available products include the bio-nanofiber "BiNFi-s" series from Sugino Machine Co., Ltd.

[0039] From the viewpoint of achieving the effects of the present application, the (C3) nanofibers preferably have an average fiber thickness of 1 nm to 1,000 nm, more preferably 5 nm to 700 nm, and even more preferably 10 nm to 500 nm. Furthermore, from the viewpoint of achieving the effects of the present application, the (C3) nanofibers preferably have an average fiber length of 0.05 μm to 10 μm, and more preferably 0.05 μm to 8 μm. The aforementioned average fiber thickness and average fiber length are the arithmetic average values ​​of 10 arbitrarily selected fibers observed with an electron microscope (e.g., a scanning electron microscope).

[0040] The cellulose used in CNF may be any cellulose that can be obtained into cellulose nanofibers by defibration, micronization, etc., and examples thereof include pulp, cotton, paper; regenerated cellulose fibers such as rayon, cupra, polynosic, and acetate; bacterially produced cellulose, animal-derived cellulose such as sea squirt, etc. Furthermore, these celluloses may be chemically surface-modified as needed, and the obtained cellulose nanofibers may be modified cellulose nanofibers in which some of the hydroxyl groups have been modified.

[0041] By including the nanofibers (C3) as the flowability control agent (C), the viscosity of the insulating composition does not change significantly from that at room temperature, even when the solid content of the insulating composition is heated to around 120° C. Therefore, when the insulating composition is applied to an object, the coating film has good coverage, and even if a volatile substance such as the solvent (D) volatilizes due to the drying temperature, the applied coating film is maintained without peeling or running off from the side surfaces and edges, including corners, of the metal part of the object, and a cured film can be formed by curing the coating film with good coverage.

[0042] The insulating composition preferably contains a solvent (D). By containing the solvent (D), the viscosity of the insulating composition can be adjusted to be low, and when the insulating composition is spray-applied, the insulating composition can be applied to an object without clogging a nozzle.

[0043] Examples of the solvent (D) that can be used include alcohol-based solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol; alcohol ether-based solvents such as ethylene glycol monomethyl ether, ethyl glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, 3-methoxy-1-butanol, and 3-methoxy-3-methyl-1-butanol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone (anone); ether-based solvents such as tetrahydrofuran and dioxane; ester-based solvents such as methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, and t-butyl acetate; aliphatic hydrocarbons such as n-propyl alcohol, hexane, heptane, and cyclohexane; aromatic solvents such as aromatic hydrocarbons such as benzene, toluene, and xylene; amide-based solvents such as formamide and dimethylformamide; and water.

[0044] The (D) solvent preferably contains a (D1) solvent having a boiling point of less than 100°C and a (D2) solvent having a boiling point of 100°C or higher. By containing a (D1) solvent having a boiling point of less than 100°C and a (D2) solvent having a boiling point of 100°C or higher, the insulating composition can be evenly applied to the target object, for example, when spray-applied, without clogging the nozzle. Even after applying the insulating composition to the target object, when drying the coating film coated with the insulating composition at a temperature of, for example, 90°C or higher but lower than 150°C, even if the (D1) solvent having a boiling point of less than 100°C volatilizes, the (D2) solvent having a boiling point of 100°C or higher remains, improving coverage even on the sides and edges of the target object without exposing the target object, and maintaining a smooth coating surface. Examples of the (D1) solvent having a boiling point of less than 100°C include ethanol and ethyl acetate. Examples of the (D2) solvent having a boiling point of 100°C or higher include water and cyclohexanone (anone). The boiling point of the (D1) solvent having a boiling point of less than 100°C is preferably 50°C or higher. The boiling point of the (D2) solvent having a boiling point of 100°C or higher is preferably 250°C or lower. When the (D) solvent contains a (D1) solvent having a boiling point of less than 100°C and a (D2) solvent having a boiling point of 100°C or higher, the (D1) solvent is preferably in the range of 70% by mass to 95% by mass, more preferably 75% by mass to 90% by mass, based on the total amount of the (D) solvents taken as 100% by mass. The (D2) solvent is preferably in the range of 5% by mass to 30% by mass, more preferably 10% by mass to 25% by mass, based on the total amount of the (D) solvents taken as 100% by mass.

[0045] The insulating composition may contain at least one additive (E) selected from the group consisting of a leveling agent, a dispersant, a dye, a coupling agent, an ion trapping agent, an antioxidant, and a flame retardant. (E) preferably contains at least one additive selected from the group consisting of a leveling agent (E1) and a dispersant (E2). Examples of the leveling agent (E1) include a silicone-based leveling agent (BYK-330, manufactured by BYK Japan Co., Ltd.). Examples of the dispersant (E2) include an organic dispersant containing silica or an organic phyllosilicate (RHEOBYK-606, manufactured by BYK Japan Co., Ltd.). Examples of the dye include a black dye (Sundan Black B, Solvent Black 3).

[0046] The insulating composition preferably has a (D) solvent content of 25% by mass or more, more preferably 50% by mass or more, even more preferably 65% ​​by mass or more, even more preferably 68% by mass or more, and preferably 80% by mass or less, and more preferably 75% by mass or less, relative to the total amount. When the insulating composition has a (D) solvent content of 25% by mass or more and 80% by mass or less, the insulating composition can be easily and uniformly applied to the target object, exhibiting good application properties and improved coverage of the target object. When the (D) solvent includes a (D1) solvent having a boiling point of less than 100°C and a (D2) solvent having a boiling point of 100°C or more, the total amount of the (D1) solvent having a boiling point of less than 100°C and the (D2) solvent having a boiling point of 100°C or more is defined as the content of the (D) solvent.

[0047] In the insulating composition, the total amount of the (A) thermosetting resin, (B) curing agent, and (C) flowability control agent is preferably in the range of 15% by mass to 35% by mass, more preferably in the range of 18% by mass to 32% by mass, and even more preferably in the range of 20% by mass to 30% by mass, based on the total amount of the insulating composition. When the total amount of the (A) thermosetting resin, (B) curing agent, and (C) flowability control agent is 15% by mass to 35% by mass based on the total amount of the insulating composition, the insulating composition can form an insulating film with good spray applicability, good coverage, and excellent insulating properties.

[0048] In order to form a coating film with good coverage and an insulating film by curing the coating film, the content of the (A) thermosetting resin in the insulating composition is preferably in the range of 0.5% by mass to 30% by mass, more preferably in the range of 1% by mass to 25% by mass, and even more preferably in the range of 1% by mass to 20% by mass, relative to the total amount of the insulating composition. When the (A) thermosetting resin contains multiple types of (A) thermosetting resins, the total amount is taken as the content of the (A) thermosetting resin.

[0049] The content of the (A) thermosetting resin relative to 100% by mass of the total solid content of the insulating composition is preferably in the range of 2% by mass to 78% by mass, more preferably in the range of 10% by mass to 75% by mass, and even more preferably in the range of 30% by mass to 73% by mass. If the content of the (A) thermosetting resin relative to 100% by mass of the solid content of the insulating composition is in the range of 2% by mass to 78% by mass, the insulating composition can form an insulating film having the required insulating properties while improving coverage.

[0050] In order to form a coating film with good coverage and a cured film obtained by curing the coating film, the content of the (B) curing agent is preferably in the range of 0.5% by mass to 10% by mass, more preferably in the range of 2% by mass to 8% by mass, and even more preferably in the range of 3% by mass to 7.5% by mass, relative to the total amount of the insulating composition. When the (B) curing agent contains multiple types of curing agents, for example, a (B1) curing agent and a (B2) curing accelerator, the total amount of the (B1) curing agent and the (B2) curing accelerator is defined as the content of the (B) curing agent.

[0051] The content of the (B) curing agent relative to 100% by mass of the total solid content of the insulating composition is preferably in the range of 20% by mass to 35% by mass, more preferably in the range of 22% by mass to 34% by mass. If the content of the (B) curing agent relative to 100% by mass of the solid content of the insulating composition is in the range of 20% by mass to 35% by mass, the insulating composition can form an insulating film having the required insulating properties while improving coverage.

[0052] In order to improve the coating properties and coverage of the insulating composition, the content of the (C) flowability control agent is preferably in the range of 0.1% by mass to 20% by mass, more preferably 0.2% by mass to 15% by mass, and even more preferably 0.2% by mass to 10% by mass, relative to the total amount of the insulating composition. When the (C) flowability control agent is a combination of at least two or more selected from the group consisting of (C1) thermoplastic resin, (C2) inorganic particles, and (C3) nanofibers, the total amount of the multiple (C) flowability control agents is defined as the content of the (C) flowability control agent. When the (C2) inorganic particles are in the form of a dispersion or mixture with other components other than the inorganic particles, the content of the (C2) inorganic particles is defined as the amount excluding the components other than the inorganic particles contained in the dispersion or mixture. When the (C3) nanofibers are in the form of a dispersion or mixture together with other components (e.g., epoxy resin) other than the nanofibers, the content of the (C3) nanofibers is the amount excluding the components other than the nanofibers contained in the dispersion or mixture. The total amount of the insulating composition also includes the amount of components other than the (C2) inorganic particles or the (C3) nanofibers contained in the dispersion or mixture. When the insulating composition contains the (C2) inorganic particles or the (C3) nanofibers in the mixture or dispersion, the thermosetting resin or thermoplastic resin contained in the mixture or dispersion is included in the total amount of the insulating composition. On the other hand, when the insulating composition contains (C2) inorganic particles or (C3) nanofibers in a mixture or dispersion, even if the mixture or dispersion contains a thermosetting resin or a thermoplastic resin, the amount of the thermosetting resin or thermoplastic resin contained in the mixture containing the (C2) inorganic particles or (C3) nanofibers that is not included in the content of the (A) thermosetting resin or the content of the (C1) thermoplastic resin in the insulating composition is defined as the content of the (A) thermosetting resin or the content of the (C1) thermoplastic resin.

[0053] The content of the (C) flowability control agent relative to 100% by mass of the total solid content of the insulating composition is preferably 50% by mass or less, more preferably 0.5% by mass to 40% by mass, even more preferably 1% by mass to 35% by mass, and even more preferably 1% by mass to 32% by mass. When the content of the (C) flowability control agent relative to 100% by mass of the solid content of the insulating composition is within the above range, the insulating composition can form an insulating film having the required insulating properties while improving coverage. When the (C2) inorganic particles or (C3) nanofibers are in a dispersion state with other components other than the inorganic particles or nanofibers, the content of the (C2) inorganic particles or (C3) nanofibers is the amount excluding components other than the inorganic particles or nanofibers contained in the dispersion. Note that the total amount of solid content also includes the amount of components other than the (C2) inorganic particles or (C3) nanofibers contained in the dispersion.

[0054] When the (C) flow control agent is a (C1) thermoplastic resin, the content of the (C1) thermoplastic resin relative to the total amount (100 mass %) of the solid content of the insulating composition is preferably in the range of 1 mass % or more and 30 mass % or less, more preferably in the range of 3 mass % or more and 20 mass % or less, and even more preferably in the range of 5 mass % or more and 15 mass % or less.

[0055] When the (C) flowability control agent is (C2) inorganic particles, the content of the (C2) inorganic particles relative to the total amount (100 mass %) of the solid content of the insulating composition is preferably in the range of 0.1 mass % to 10 mass %, more preferably in the range of 0.5 mass % to 5 mass %, and even more preferably in the range of 1 mass % to 3 mass %.

[0056] When the (C) flow control agent is (C3) nanofiber, the content of the (C3) nanofiber relative to the total amount (100 mass %) of the solid content of the insulating composition is preferably in the range of 0.1 mass % to 15 mass %, more preferably in the range of 0.3 mass % to 10 mass %, and even more preferably in the range of 0.5 mass % to 5 mass %.

[0057] When the insulating composition contains an additive (E), the content of the additive (E) is preferably 5% by mass or less, or may be 4% by mass or less, or may be 3.5% by mass or less, relative to the total amount of the insulating composition. The insulating composition does not need to contain an additive (E), and when it contains an additive (E), the content is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. The additive (E) contained in the insulating composition may be used alone, or two or more types may be used in combination. When the insulating composition (E) contains an additive and two or more types of additive (E) are used in combination, the total amount of the two or more additive (E) types is the content of the additive (E).

[0058] The content of the (E) additive is preferably 2% by mass or less relative to 100% by mass of the solid content of the insulating composition. It may also be 1.5% by mass or less. The solid content may not contain the (E) additive. The (E) additive may be contained in an amount of 0.1% by mass or more, or 0.2% by mass or more relative to 100% by mass of the total solid content.

[0059] The insulating composition can be produced by blending and stirring other components including (A) a thermosetting resin, (B) a curing agent, (C) a flow control agent, and optionally (D) a solvent, and optionally (E) an additive.

[0060] The solid content of the insulating composition may be produced by blending and stirring other components including (A) a thermosetting resin, (B) a curing agent, (C) a flow control agent, and (E) an additive as needed. The viscosity of the solid content of the produced insulating composition can be measured using a rheometer. The solid content of the produced insulating composition is measured by the rheometer under the conditions of 120°C and 100 rpm to obtain a viscosity V Ｒ１２０ The solid content of the insulating composition thus produced can be measured by a rheometer at 25°C and 100 rpm to determine the viscosity V Ｒ２５ The insulating composition can be produced by adding a solvent (D) to the solid content of the insulating composition.

[0061] To produce the solid content of the insulating composition or the insulating composition itself, for example, the components can be stirred and mixed using known devices. For example, mixing can be performed using known devices such as a hybrid mixer, a Henschel mixer, a roll mill, or a triple roll mill. The raw materials for each component may be added and mixed simultaneously, or some may be mixed first and the rest may be mixed later.

[0062] Examples of a method for applying the insulating composition to an object include spray application. For spray application, an ultrasonic spray device or the like can be used. In addition to spray application, the insulating composition may be applied to an object by any of the following application methods: dip application, bar coater application, gravure application, reverse gravure application, or spin coater application. Furthermore, the insulating composition may be applied to an object by any of the following printing methods: lithographic printing, carton printing, metal printing, offset printing, screen printing, gravure printing, flexographic printing, or inkjet printing. The insulating composition is preferably for spray application.

[0063] The insulating composition may be applied to an object that has been heated to a temperature in the range of, for example, 40° C. or higher and 120° C. or lower. The temperature of the object to which the insulating composition is applied or the atmosphere in which the insulating composition is applied to the object is preferably in the range of 50° C. or higher and 120° C. or lower, more preferably in the range of 60° C. or higher and 110° C. or lower, and even more preferably in the range of 70° C. or higher and 100° C. After being applied to the object, the insulating composition is preferably left to stand for 1 minute to 10 minutes, and more preferably for 1 minute to 5 minutes.

[0064] The coating film obtained by applying the insulating composition to the object is preferably cured by heating to a temperature in the range of 40° C. to 200° C. after application, or after application and leaving to stand. The temperature for curing the coating film is more preferably in the range of 50° C. to 190° C., and even more preferably in the range of 60° C. to 180° C. The time for curing the coating film is preferably 1 minute to 1 hour, may be 5 minutes to 50 minutes, or may be 10 minutes to 45 minutes.

[0065] A cured film obtained by applying an insulating composition as a coating composition to an object and curing the resulting coating is insulating and serves as an insulating film. A cured film obtained by applying an insulating composition for coating to an object and curing the resulting coating can be used as an insulating film for electronic components. The cured film can be used as a highly safe insulating film that imparts insulating properties to specific portions of a metal plate that functions as a lead or heat sink on which a chip of an electronic component such as a vertical cavity surface emitting laser (VCSEL) is arranged. The insulating composition is preferably for forming an insulating film. The insulating composition is preferably for coating.

[0066] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. In the following examples and comparative examples, the figures indicating the blending ratios of each component contained in the insulating composition or the solid content of the insulating composition represent mass % unless otherwise specified. When component (C) was previously dispersed in an epoxy resin dispersion and used in the form of a dispersion or mixture, the amount of component (C) excluding components other than component (C) contained in the dispersion or mixture is reported as the content of component (C), and the epoxy resin dispersion is reported as component (A) in Tables 1 and 2.

[0067] (A) Thermosetting Resins (A1) Alkylphenol-type epoxy resin (EXA-820D, epoxy equivalent 200 to 250 g / eq., manufactured by DIC Corporation) (A2) Mixture of bisphenol F-type epoxy resin and bisphenol A-type epoxy resin (EXA-835LV, epoxy equivalent 160 to 170 g / eq., weight-average molecular weight 210, manufactured by DIC Corporation) (A3) Naphthalene-type epoxy resin (4032D, epoxy equivalent 136 to 148 g / eq., weight-average molecular weight 280, manufactured by DIC Corporation)

[0068] (B) Curing Agent (B1) Amine-based curing agent (Kayahard HDAA, manufactured by Nippon Kayaku Co., Ltd.) (B2) Curing accelerator, 2-ethyl-4-methylimidazole (2E4MZ, manufactured by Shikoku Chemicals Corporation)

[0069] (C) Flowability control agent (C1) Thermoplastic resin, phenoxy resin (PKHH, weight average molecular weight 52,000, glass transition temperature (Tg) 110°C, manufactured by Gabriel Phenoxies) (C2) Inorganic particles (YA010C-JPGZ, average particle size: 10 nm, manufactured by Admatechs Co., Ltd.) (C3-1): Nanofiber, CNF (cellulose nanofiber) ("CNF fiber length: 100 nm to 1,000 nm", "CNF fiber thickness: 3 nm") (C3-2): Nanofiber, CNF (cellulose nanofiber) ("CNF fiber length: 2.5 μm", "CNF fiber thickness: 10 nm")

[0070] (D) Solvents (D1) Solvents with a boiling point of less than 100°C, ethyl acetate (boiling point 77.1°C) (D2) Solvents with a boiling point of 100°C or more, cyclohexanone (anone) (boiling point 155.6°C)

[0071] (E) Additives (E1) Leveling agent, a silicone-based leveling agent (BYK-330, manufactured by BYK Japan Co., Ltd.) (E2) Dispersant, an organic dispersant containing silica or organic phyllosilicate (RHEOBYK-606, manufactured by BYK Japan Co., Ltd.)

[0072] Solid Content of Insulating Composition Examples 1 to 10, Comparative Example 1 The solid content of each insulating composition of the Examples and Comparative Examples was produced by stirring (A) thermosetting resin, (B) curing agent, (C) flowability control agent, and, if necessary, (E) additives in the blending ratios shown in Table 1 at 1200 rpm for 60 seconds using a hybrid mixer (manufactured by Thinky Corporation, product name "Awatori Rentaro ARE-310"). The solid content of the insulating composition refers to a state in which no volatile substances such as solvents are contained.

[0073] Viscosity change rate of solid content of insulating composition HAKKE ＴＭ MARS ＴＭ Using a 35 mm diameter (35 mmφ) parallel cone rheometer (manufactured by Thermo Scientific), the viscosity is measured from 25°C to 150°C at a temperature rising rate of 5°C / min at a rotation speed of 100 rpm at each temperature. The viscosity of each solid measured at 25°C and 100 rpm is designated as V.Ｒ２５ The viscosity of each solid measured under the conditions of 120°C and 100 rpm is V Ｒ１２０ and the viscosity V Ｒ２５ Viscosity V Ｒ１２０ Viscosity change rate (V Ｒ１２０ / V Ｒ２５ × 100) are shown in Table 1. Figure 1 shows the change in viscosity measured from 25°C to 150°C for each solid content of Examples 1 to 5 and the solid content of Comparative Example 1. In Table 1 or Table 2, the symbol "-" indicates that there is no value or evaluation for the corresponding item.

[0074]

[0075] As shown in Table 1, the insulating compositions of Examples 1 to 10 had a viscosity V Ｒ１２０ As shown in Table 2 below, the coating film has good coverage on the target object, and the coating film is maintained without peeling or running off even on the side surfaces and edges including corners of the metal part to be coated, and a cured film can be formed by curing the coating film with good coverage. Furthermore, the solid content of the insulating compositions of Examples 1 to 10 has a viscosity change rate (V Ｒ１２０ / V Ｒ２５ × 100) is 10% or more and 50% or less.

[0076] The insulating composition of Comparative Example 1 had a viscosity V Ｒ１２０ As shown in Table 2 below, when an insulating composition containing the (D) solvent is applied to a copper plate, the thickness of the corners of the cured film is less than 1.0 μm, and the coverage is poor.

[0077] 1 is a graph showing the relationship between temperature and viscosity measured with a rheometer when the solid content of the insulating compositions of Examples 1, 2, 4, and 10 and the insulating composition of Comparative Example 1 was heated from 25° C. to 150° C. As shown in FIG. 1, the solid content of the insulating compositions of Examples containing the flowability control agent (C) showed a reduced decrease in viscosity when heated from 80° C. to 150° C. compared to the solid content of the insulating composition of Comparative Example 1 not containing the flowability control agent (C). Even when applied to an object and dried or heated, the viscosity did not decrease significantly, and the coverage of the side surfaces and edges, including corners, of the object was good.

[0078] Insulating Compositions Examples 1 to 10 and Comparative Example 1 Each insulating composition of the Examples and Comparative Examples was produced by mixing (A) thermosetting resin, (B) curing agent, (C) flow control agent, (D) solvent, and, if necessary, (E) additive in the blending ratios shown in Table 2 at 1200 rpm for 60 seconds using a hybrid mixer (manufactured by Thinky Corporation, product name "Awatori Rentaro ARE-310").

[0079] Viscosity of Insulating Composition For each insulating composition of the Examples and Comparative Examples, the viscosity V was measured at 25°C and 100 rpm using a Brookfield rotational viscometer LVDV-II Pro (manufactured by Brookfield) and SPC-41Z Spindle as a B-type viscometer. Ｂ２５（１００） Measure V at 25°C and 10 rpm Ｂ２５（１０） The viscosity V measured at 25°C and 100 rpm Ｂ２５（１００） and viscosity V at 10 rpm Ｂ２５（１０） and viscosity V at 100 rpm Ｂ２５（１００） The ratio (V Ｂ２５（１０） / V Ｂ２５（１００） The thixotropy index TI is given in Table 2.

[0080] Spray Coatability When each insulating composition of the Examples and Comparative Examples was sprayed onto a copper plate, which was a metal plate, using an ExactaCoat ultrasonic spray device (manufactured by Sono-TEK Corporation), it was visually confirmed whether there was any problem with nozzle clogging or liquid accumulation due to poor atomization. If no problem was found, it was rated as "Good." If a problem was found, it was rated as "Not Good." If spray coating was not possible, it was rated as "Bad." The results are shown in Table 2.

[0081] Coverage Each insulating composition in the Examples and Comparative Examples was applied to the surface of a copper plate, which was a metal plate, as follows, to form a coating film and a cured film by curing the coating film. A masking film having a hole measuring 3 mm in length and 2 mm in width was placed on a heating stage (heater collet), and a rectangular copper plate measuring 3 mm in length, 2 mm in width, and 1 mm thick was placed in the hole measuring 3 mm in length and 2 mm in width in the masking film, and the copper plate was heated so that its surface temperature reached 85°C. Using an ExactaCoat ultrasonic spray device (manufactured by Sono-TEK Corporation), the insulating composition was sprayed onto the copper plate twice, once from one side of the rectangle toward the opposite side, and once from the other side toward the opposite side. To dry, the copper plate was left to stand for 2 minutes while the surface temperature was kept at 85°C. Thereafter, the rectangular copper plate was sprayed twice, once from one side toward the opposite side, and once from the other side toward the opposite side. The spray coating was performed four times in total, before and after standing still. The copper plate was heated for 30 minutes so that the surface temperature reached 170°C, and the coating film coated with the insulating composition was cured to form a cured film. The copper plate on which the cured film was formed was used as a sample. The appearance and cross-section of the copper plate on which the cured film was formed were observed using a CCD image sensor, and the thickness of the cured film was measured. A film thickness at the corners of the cross section of 1.0 μm or more was evaluated as good (G: Good), a film thickness at the corners of the cross section of less than 1.0 μm was evaluated as fair (F: Fair), and a film thickness at the corners of the cross section of 0.5 μm or less was evaluated as poor (NG: No Good). The results are shown in Table 2.

[0082] Evaluation by Cross-Cut Test In the same manner as in the sample for evaluating coverage described above, the insulating composition was spray-coated onto a copper plate using an ExactaCoat ultrasonic spray device (manufactured by Sono-TEK Corporation) to form a coating film, which was then heated at 170°C for 30 minutes to cure the coating film and form a cured film with a thickness of 10 μm. The copper plate on which the cured film was formed was used as a sample. In accordance with ASTM D3359-97, a total area of ​​5 mm in length and 5 mm in width was used as the measurement target. Six vertical and six horizontal incisions were made in a checkerboard pattern at 1 mm intervals within the total area, and cellophane tape (manufactured by Nichiban Co., Ltd.) was then applied to the intersecting incisions. The applied cellophane tape was then peeled off, and the area of ​​the peeled cured film was measured and evaluated on a six-point scale from 0B to 5B as follows. The results are shown in Table 2. 5B: No peeling (0% peeled area) 4B: Peeling area was 5% or less of the total area. 3B: The peeled area is more than 5% and not more than 15% of the total area. 2B: The peeled area is more than 15% and not more than 35% of the total area. 1B: The peeled area is more than 35% and not more than 65% of the total area. 0B: The peeled area is more than 65% of the total area.

[0083] Insulation Resistance Value In the same manner as in the sample for which coverage was evaluated above, the insulating composition was spray-coated onto a copper plate using an ExactaCoat ultrasonic spray device (manufactured by Sono-TEK Corporation) to form a coating film, which was then heated at 170°C for 30 minutes to cure the coating film, forming a cured film with a film thickness of 10 μm. The copper plate on which the cured film was formed was used as a sample. One side of the copper plate and one side of the cured film were fixed with electrode probes, and the insulation resistance value was measured using a system source meter (manufactured by KEITHLEY Corporation, trade name Model 2611B) by applying a voltage of 100 V and a maximum current of 0.1 mA. The results are shown in Table 2.

[0084] Thermal Conductivity: In the same manner as in the sample for which coverage was evaluated above, the insulating composition was spray-coated onto a 0.3 mm thick copper plate using an ExactaCoat ultrasonic spray device (manufactured by Sono-TEK Corporation) to form a coating film with a thickness of 15 μm ± 5 μm (10 μm to 20 μm), which was then heated at 170°C for 30 minutes to cure the coating, forming a cured film with a thickness of 15 μm ± 5 μm (10 μm to 20 μm). The copper plate on which the cured film was formed was used as the sample. The thermal conductivity of the composite of the cured film and copper plate was measured using an LFA467 flash analyzer (manufactured by TZSC). The specific heat of the cured film required for calculating thermal conductivity was measured by the DSC method using a differential scanning calorimeter (DSC204F1, manufactured by NETZCS). The specific gravity of the cured film required for calculating the specific heat was measured by the Archimedes method. The thermal conductivity of the copper plate is 398 W / mK. The rate of change in thermal conductivity, which is the ratio of the thermal conductivity of the composite of the cured film and the metal plate to the thermal conductivity of the copper plate (the metal plate), is measured (thermal conductivity of the composite / thermal conductivity of the metal plate × 100). The ratio of the thermal conductivity of the composite to the thermal conductivity of the metal plate (thermal conductivity of the composite / thermal conductivity of the metal plate × 100) is shown in Table 2 as the rate of change in thermal conductivity (%).

[0085]

[0086] As shown in Tables 1 and 2, the insulating compositions of Examples 1 to 10 had a viscosity V measured with a Brookfield viscometer at 25° C. and 100 rpm. Ｂ２５（１００） More specifically, the insulating compositions of Examples 1 to 10 have a viscosity V Ｂ２５（１００） The insulating composition of Example 11 has a viscosity V Ｂ２５（１００） The insulating compositions of Examples 1 to 11 have a thixotropy index TI (V Ｂ２５（１０） / V Ｂ２５（１００） ) is 3.0 or less.

[0087] The insulating compositions of Examples 1 to 10 have good spray applicability and coverage (Good). Furthermore, the insulating compositions of Examples 1 to 10 all received a cross-cut test rating of 5B based on ASTM D3359-97, demonstrating excellent adhesion between the cured film made of the insulating composition and the copper plate. The cured films made of the insulating compositions of Examples 1 to 10 have an insulation resistance value of 50 MΩ or higher, demonstrating excellent insulating properties. The cured films made of the insulating compositions of Examples 1 to 10 have a composite of the cured film and the metal plate with a thermal conductivity of 260 W / mK or higher, and a thermal conductivity ratio (thermal conductivity of the composite / thermal conductivity of the metal plate × 100), which is the ratio of the thermal conductivity of the composite to the thermal conductivity of the copper plate, is 60% or higher, maintaining the high thermal conductivity of the copper plate. The cured films made of the insulating compositions of Examples 1 to 10 have excellent insulating properties while maintaining high thermal conductivity.

[0088] As shown in Tables 1 and 2, the insulating composition of Comparative Example 1, which did not contain the flow control agent (C), had a viscosity V measured with a Brookfield viscometer at 25° C. and 100 rpm. Ｂ２５（１００） The viscosity V of the solid content of the insulating composition of Comparative Example 1 is 600 mPa·s or less. Ｒ１２０ is less than 28 mPa·s, and the coverage is poor.

[0089] The insulating composition according to an embodiment of the present disclosure can be used as a coating composition (insulating composition for coating) for forming an insulating film to impart insulating properties to a metal part. The insulating composition can also be used as a spray coating composition (insulating composition for spray coating) for forming an insulating film by spray application. The coating composition can be used as an insulating coating composition for electronic components to be mounted on a substrate. Specifically, a cured film obtained by curing a coating film applied to an object can be used as a highly safe insulating film that imparts insulating properties to specific portions of a metal plate that functions as a lead for arranging a chip of an electronic component such as a vertical-cavity surface-emitting laser (VCSEL) or a metal plate that functions as a heat sink.

Claims

1. An insulating composition comprising (A) a thermosetting resin, (B) a curing agent, and (C) a flow control agent, wherein the solid content of the insulating composition has a viscosity V measured by a rheometer at 120°C and 100 rpm. Ｒ１２０ An insulating composition characterized in that the viscosity is 28 mPa·s or more.

2. The insulating composition further contains (D) a solvent, and the insulating composition has a viscosity V measured with a Brookfield viscometer at 25°C and 100 rpm. Ｂ２５（１００） The insulating composition according to claim 1 , wherein the viscosity is 600 mPa·s or less.

3. Viscosity V measured using a Brookfield viscometer at 25°C and 100 rpm Ｂ２５（１００） Viscosity V measured with a Brookfield viscometer at 25°C and 10 rpm Ｂ２５（１０） The ratio (V Ｂ２５（１０） / V Ｂ２５（１００） 3. The insulating composition according to claim 2, wherein the thixotropy index value TI is 3.0 or less.

4. An insulating composition according to any one of claims 1 to 3, wherein the insulating composition is applied to a coating film having a thickness of 10 μm after curing, and the cured film is cured, and when a voltage of 100 V is applied to the cured film, the insulating resistance value is 50 MΩ or more.

5. The insulating composition according to any one of claims 1 to 4, wherein the insulating composition is applied to the surface of a copper plate, the coating is cured, and the surface of the cured film is subjected to a cross-cut test in accordance with ASTM D3359-97 standard, and the result is 3B or higher.

6. The solid content of the insulating composition is measured using a rheometer at 25°C and 100 rpm to determine the viscosity V Ｒ２５ Viscosity V measured with a rheometer at 120 ° C. and 100 rpm Ｒ１２０ The ratio (V Ｒ１２０ / V Ｒ２５ 6. The insulating composition according to claim 1, wherein the value of (x100) is 10% or more.

7. The insulating composition according to any one of claims 1 to 6, wherein the thermosetting resin (A) includes an epoxy resin.

8. An insulating composition according to any one of claims 1 to 7, wherein the (C) flow control agent comprises at least one selected from the group consisting of (C1) a thermoplastic resin, (C2) inorganic particles, and (C3) nanofibers.

9. An insulating composition according to any one of claims 1 to 8, comprising, as the (C) flowability control agent, a (C1) thermoplastic resin having a weight average molecular weight of 10,000 or more and 100,000 or less.

10. An insulating composition according to any one of claims 1 to 9, wherein the (C) flow control agent contains (C1) a thermoplastic resin having a glass transition point (Tg) of 160°C or less.

11. The insulating composition according to any one of claims 1 to 10, wherein the (C) flowability control agent contains (C2) inorganic particles having an average particle size of 1 μm or less.

12. An insulating composition according to any one of claims 1 to 11, comprising (C3) nanofibers as the (C) flow control agent, the (C3) nanofibers being cellulose fibers.

13. An insulating composition according to any one of claims 1 to 12, containing the flow control agent (C) in an amount of 0.1 mass % or more and 20 mass % or less relative to the total amount.

14. An insulating composition according to claim 2 or any one of claims 3 to 13 that cite claim 2, wherein the (D) solvent includes a (D1) solvent having a boiling point of less than 100°C and a (D2) solvent having a boiling point of 100°C or higher.

15. An insulating composition according to any one of claims 1 to 14, wherein the insulating composition is applied to a metal plate to form a coating film having a thickness of 10 μm after curing, and the cured film is cured to form a composite of the metal plate and the cured film, and the ratio of the thermal conductivity of the composite to the thermal conductivity of the metal plate (thermal conductivity of the composite / thermal conductivity of the metal plate × 100) is 60% or more.

16. An insulating composition according to any one of claims 1 to 15, which is for spray application.

17. An insulating composition according to any one of claims 1 to 15, which is used for coating.

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