TW202413562A - Low-dielectric-constant insulating coating composition, cured product of same, and display device - Google Patents

Abstract

The present invention is a low-dielectric-constant insulating coating composition containing: (A) a reaction adduct of an organic silicon compound represented by formula (1) and an organic silicon compound represented by formula (2), the reaction adduct having three or more SiH groups in a molecule; (B) an organosiloxane compound having two or more alkenyl groups in a molecule; and (C) a hydrosilylation reaction catalyst. A low-dielectric-constant insulating coating composition in which a cured product obtained by curing has a high mechanical strength and a low dielectric constant and dissipation tangent is thereby provided. (In the formulas, R1 is an independently substituted or unsubstituted divalent C1-12 hydrocarbon group, R2 is an independently substituted or unsubstituted monovalent C1-12 hydrocarbon group, and R3 is a single bond or an unsubstituted divalent C1-4 hydrocarbon group).

Description

Low dielectric constant insulating coating composition, cured product thereof and display device

The present invention relates to a low dielectric constant insulating coating composition, a cured product thereof and a display device.

In recent years, information and communication equipment has advanced rapidly. With the large-capacity communication of image information, the digitalization and high-frequency transmission of signals have continued to advance. Therefore, as a material with less transmission loss in the gigahertz high-frequency region, a resin material with better processability and handling than the fluororesins and ceramics that have been used until now is sought.

For example, a bismaleimide resin composition has been proposed, which has a low dielectric constant and a low dielectric loss tangent and can provide a cured product with excellent heat resistance, toughness and good workability (Patent Document 1). However, further improvements are still desired.

On the other hand, as a curable composition used as a sealing material for white LEDs that require heat resistance, a curable composition has been proposed, which contains the following components as essential components: a compound having three or more hydrogen atoms bonded to silicon atoms in one molecule; an organic siloxane having two or more alkenyl groups in one molecule; and a silylation catalyst (Patent Document 2). The curable composition is considered to be a cured product that has high hardness, mechanical strength, and crack resistance and can impart light transmittance in the short wavelength region and excellent gas barrier properties. However, the document does not mention the dielectric properties of the cured product at all. [Prior Technical Document] (Patent Document)

Patent document 1: Japanese Patent Publication No. 2021-181532. Patent document 2: Japanese Patent Publication No. 2020-026502.

[Problem to be solved by the invention] In the prior art, there is still a problem that it is impossible to obtain a hardened material that has both low dielectric properties (low dielectric constant and low dielectric loss tangent) and high mechanical strength. Therefore, the present invention is made in view of the above technical problems, and the purpose is to provide a low dielectric constant insulating coating composition, the hardened material obtained by hardening has high mechanical strength and low relative dielectric constant and dielectric loss tangent. [Technical means to solve the problem]

To solve the above problems, the present invention provides a low dielectric constant insulating coating composition, which comprises the following components (A), (B) and (C): (A) an addition reaction product, which is an addition reaction product of an organic silicon compound represented by the following general formula (1) and an organic silicon compound represented by the following general formula (2), and has three or more SiH groups in one molecule, (In the general formula (1), R ¹ is independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms), (In the general formula (2), ^R2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and ^R3 is a single bond or an unsubstituted divalent hydrocarbon group having 1 to 4 carbon atoms); (B) an organosiloxane compound having two or more alkenyl groups in one molecule; and, (C) a hydrosilylation catalyst.

The low dielectric constant insulating coating composition of the present invention can provide a low dielectric constant insulating coating composition that can provide a hardened material with high mechanical strength and low relative dielectric constant and dielectric loss tangent. Furthermore, in the present invention, the relative dielectric constant (the ratio of the dielectric constant relative to vacuum) is also referred to as "dielectric constant".

In the low dielectric constant insulating coating composition of the present invention, the above ^R1 can be a phenylene group, and the above ^R2 can be a methyl group or a phenyl group.

Such an organic silicon compound represented by the general formula (1) and an organic silicon compound represented by the general formula (2) are easily available, and the component (A) as the addition reaction product can be obtained efficiently.

In the low dielectric constant insulating coating composition of the present invention, it is further preferred that the component (B) is a compound represented by the following general formula (3): (In the general formula (3), ^R4 is independently an unsubstituted or substituted monovalent alkyl group, ^R5 is independently a methyl group or a phenyl group, a is an integer from 0 to 50, and b is an integer from 0 to 100; however, when a is 0, ^R5 is a phenyl group and b is 1 to 100; the arrangement of the siloxane units in parentheses is in any order).

Such component (B) can be easily obtained.

In addition, the present invention provides a hardened material, which is characterized by being formed by hardening the above-mentioned low dielectric constant insulating coating composition.

The hardened material of the present invention has excellent mechanical strength and low relative dielectric constant and dielectric loss tangent.

The cured product of the present invention preferably has a dielectric constant of 3.0 or less and a dielectric loss tangent of 0.01 or less at 10 GHz.

Any hardened material with such low dielectric constant insulation can be used to make insulating materials, coating materials, and sealing materials with low transmission loss in high-frequency regions.

Furthermore, the present invention provides a display device, characterized in that it has a layer composed of the above-mentioned hardened material.

As long as it is a display device of the present invention, in addition to the high mechanical strength of the hardened material used, and having a low relative dielectric constant and dielectric loss tangent, it also has transparency, so it will become a display device with high reliability. [Effect of the invention]

The low dielectric constant insulating coating composition of the present invention has a high mechanical strength of the hardened product and has a low relative dielectric constant and a low dielectric loss tangent, so it is helpful to make a coating material with low transmission loss in the high frequency region and used for electronic devices and electrical devices.

As mentioned above, it is desirable to develop a low dielectric constant insulating coating composition that can impart a hardened product with high mechanical strength and low relative dielectric constant and dielectric loss tangent.

The inventors have devoted themselves to studying the above technical problems and have found that a low dielectric constant insulating coating composition containing specific components can solve the above technical problems, thereby completing the present invention.

That is, the present invention is a low dielectric constant insulating coating composition, which comprises the following components (A), (B) and (C): (A) an addition reaction product, which is an addition reaction product of an organic silicon compound represented by the following general formula (1) and an organic silicon compound represented by the following general formula (2), and has three or more SiH groups in one molecule, (In the general formula (1), R ¹ is independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms), (In the general formula (2), ^R2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and ^R3 is a single bond or an unsubstituted divalent hydrocarbon group having 1 to 4 carbon atoms); (B) an organosiloxane compound having two or more alkenyl groups in one molecule; and, (C) a hydrosilylation catalyst.

The present invention is described in detail below, but the present invention is not limited thereto.

[Low dielectric constant insulating coating composition] The low dielectric constant insulating coating composition of the present invention is an addition-curing silicone composition, which contains the following components (A) to (C). The low dielectric constant insulating coating composition of the present invention can be prepared by mixing the following components (A) to (C) and other components as needed using a conventionally known method. The following describes each component in detail.

[Component (A)] Component (A) in the low dielectric constant insulating coating composition of the present invention functions as a crosslinking agent by inducing a silylation reaction with component (B) described later.

The component (A) is an addition reaction product of an organic silicon compound represented by the following general formula (1) and an organic silicon compound represented by the following general formula (2), and has three or more SiH groups (silicon hydrogen groups) in one molecule. (In the general formula (1), R ¹ is independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms), (In the general formula (2), ^R2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and ^R3 is a single bond or an unsubstituted divalent hydrocarbon group having 1 to 4 carbon atoms).

Furthermore, the organic silicon compound represented by the general formula (2) does not have a siloxane bond having three alkenyl groups in one molecule, and therefore can be clearly distinguished from the component (B) which is an organic silicon compound having two or more alkenyl groups in one molecule.

Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms represented by ^R1 include alkylene groups such as methylene, ethylene, n-propylene, n-butylene, n-pentyl, n-hexyl, cyclohexyl and n-octyl; aryl groups such as phenylene and naphthyl; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine and chlorine. Particularly preferred as ^R1 is phenylene.

Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms represented by ^R2 include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl and octyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl and propenyl; aryl groups such as phenyl, tolyl, xylyl and naphthyl; aralkyl groups such as benzyl, phenethyl and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine and chlorine. ^R2 is particularly preferably methyl or phenyl, and particularly preferably phenyl.

Examples of the unsubstituted divalent hydrocarbon group having 1 to 4 carbon atoms represented by R ³ include alkylene groups such as methylene, ethylene, n-propylene, and n-butylene. When R ³ is a single bond, it represents an organic silicon compound in which a vinyl group is directly bonded to a silicon atom. R ³ is particularly preferably a single bond, methylene, or ethylene.

Suitable specific examples of the organosilicon compound represented by the general formula (1) are shown below, but the present invention is not limited thereto. The organosilicon compound represented by the general formula (1) may be used alone or in combination of two or more.

Suitable specific examples of the compound represented by the general formula (2) are shown below, but the present invention is not limited thereto. The compound represented by the general formula (2) may be used alone or in combination of two or more.

Preferred examples of the component (A) of the addition reaction product of the organosilicon compound represented by the above general formula (1) and the organosilicon compound represented by the above general formula (2) include compounds represented by the following unit formula. (In the general formula, n is an integer from 1 to 10.)

As specific examples of the compound represented by the aforementioned unit general formula, compounds represented by the following formulas and the like can be cited, but the present invention is not limited thereto.

As the component (A), the compound represented by the above unit formula may be used alone or in combination of two or more. In this case, it is preferred that: among the compounds represented by the aforementioned unit formula, if n is 1 and is referred to as ^N1 , n is ² and is referred to as N2, n is ³ and is referred to as ^N3 , and similarly hereinafter, n is ^k and is referred to as ^Nk , the molar fraction of each compound in a mixture consisting of compounds ^N1 , ^N2 , ^N3 , ^N4 ... ^Nk (the mass of each compound when the total mass of ^N1 , ^N2 , N3, ^N4 ...Nk is taken as 1 mol) is set to the following range: _FN1 : _FN2 : _FN3 =50-60:20-30:5-15 (mol %) (wherein _FNk represents the molar fraction of compound ^Nk ) The remaining compounds are ^N4 or more ( ^N4 ~Nk ⁾ _. The total molar fraction of ) can be set to 5 to 15 (mol)%. If such an amount of (A) component is used, the mechanical strength of the cured product will be improved, so it is preferred.

[Preparation of component (A)] The component (A) in the low dielectric constant insulating coating composition of the present invention can be obtained by mixing the compound represented by the general formula (1) in an excess amount, preferably more than 3 mol and less than 30 mol, more preferably more than 4.5 mol and less than 15 mol, relative to 1 mol of the compound represented by the general formula (2), and subjecting the two to a silylation reaction in the presence of a catalyst.

As the catalyst used in the aforementioned hydrosilylation reaction, known materials can be used. Examples include: platinum-based catalysts such as carbon powder carrying platinum metal, platinum black, platinum chloride, chloroplatinic acid, reaction products of chloroplatinic acid and monohydric alcohol, complexes of chloroplatinic acid and olefins, and platinum diacetate; and platinum group metal-based catalysts such as palladium-based catalysts and rhodium-based catalysts. In addition, there are no particular limitations on addition reaction conditions, refining conditions, use of solvents, etc., and known methods can be used.

The component (A) in the low dielectric constant insulating coating composition of the present invention may be composed of one compound or a combination (mixture) of two or more compounds.

The presence of three or more SiH groups in one molecule of the compound constituting component (A) can be confirmed by selecting an appropriate measuring means. When there are two or more compounds constituting component (A), the presence of three or more SiH groups in one molecule of each compound can be confirmed by selecting a combination of appropriate measuring means (e.g., ¹ H-NMR and GPC, etc.).

[Component (B)] Component (B) in the low dielectric constant insulating coating composition of the present invention is an organic siloxane compound having two or more alkenyl groups in one molecule. Component (B) and component (A) undergo an addition reaction in the presence of a silylation catalyst (C) described later. As the organic siloxane compound, linear, branched, or cyclic organic polysiloxanes can be used.

Specific examples of the component (B) are not particularly limited, and include: dimethylsiloxane-methylvinylsiloxane copolymers having trimethylsiloxy groups terminated at both ends of the molecular chain, dimethylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymers having trimethylsiloxy groups terminated at both ends of the molecular chain, and dimethylsiloxane-diphenylsiloxane copolymers having dimethylvinylsiloxane groups terminated at both ends of the molecular chain. The component (B) may be used alone or in combination of two or more.

The component (B) preferably has 0.10 to 0.90 mol of vinyl or other alkenyl groups per 100 g, and more preferably has 0.20 to 0.50 mol. Such a component (B) has sufficient alkenyl groups that can undergo addition reaction (crosslinking), so the cured product imparted thereto will have high hardness and high strength. In addition, the component (B) preferably has a viscosity of 5 to 3000 mPa·s at 25°C, and more preferably 10 to 2000 mPa·s. Such a component (B) exhibits good fluidity at room temperature, is easy to prepare the composition, and has an appropriate viscosity when applied to a substrate, and has excellent operability. In the present invention, the viscosity at 25°C can be measured using a B-type rotational viscometer in accordance with Japanese Industrial Standard JIS-K7117-1:1999.

As the component (B), a compound represented by the following general formula (3), that is, a linear organic polysiloxane is preferred. (In the general formula (3), ^R4 is independently an unsubstituted or substituted monovalent alkyl group, ^R5 is independently a methyl group or a phenyl group, a is an integer from 0 to 50, and b is an integer from 0 to 100; however, when a is 0, ^R5 is a phenyl group and b is 1 to 100; the arrangement of the siloxane units in parentheses is in any order.)

As the unsubstituted or substituted monovalent hydrocarbon group represented by ^R4 , there can be listed aliphatic unsaturated groups and monovalent hydrocarbon groups other than aliphatic unsaturated groups, for example: alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tertiary butyl, etc.; halogenated alkyl groups having 1 to 4 carbon atoms such as chloromethyl, 3,3,3-trifluoropropyl, etc.; aryl groups having 6 to 10 carbon atoms such as phenyl, tolyl, etc.; alkenyl groups such as vinyl, allyl, etc. Among them, alkyl groups having 1 to 6 carbon atoms, phenyl, and vinyl are preferred, and methyl is particularly preferred.

In the above general formula (3), a is an integer of 0 to 50, preferably 1 to 10, more preferably 1 to 7, and further preferably 2 to 4. b is an integer of 0 to 100, preferably 0 to 50, more preferably 1 to 10, and further preferably 2 to 4. However, when a is 0, R ⁵ is a phenyl group and b is 1 to 100. The arrangement of the siloxane units in parentheses is in any order.

The organopolysiloxane represented by the general formula (3) can be obtained, for example, by hydrolyzing and condensing a difunctional silane such as dichlorodiphenylsilane or dialkoxydiphenylsilane, or by simultaneously hydrolyzing and condensing the difunctional silane and then capping the terminal with a siloxane unit containing an aliphatic unsaturated group.

The amount of component (B) can be adjusted so that the molar ratio of SiH groups to aliphatic unsaturated groups in the composition (SiH groups/aliphatic unsaturated groups) is 0.5 or more and 5 or less, and preferably 0.8 or more and 2 or less. When the molar ratio (SiH groups/aliphatic unsaturated groups) is 0.5 or more and 5 or less, the cured product of the present invention can be sufficiently cured.

[Component (C)] As the hydrosilicic catalyst of the component (C) of the present invention, the same component as that used in the preparation of the above-mentioned component (A) can be used.

The amount of component (C) of the low dielectric constant insulating coating composition of the present invention is preferably 1 to 500 ppm, more preferably about 1 to 100 ppm, and even more preferably 2 to 12 ppm in terms of platinum group metal atoms relative to the mass of the entire composition from the viewpoint of promoting the reaction and preventing coloring of the cured product.

[Other ingredients] In addition to the above-mentioned components (A) to (C), the low dielectric constant insulating coating composition may also contain antioxidants, inorganic fillers and other ingredients as needed.

[Antioxidant] In the cured product of the low dielectric constant insulating coating composition of the present invention, the addition-reactive carbon-carbon double bonds in the above-mentioned component (B) may remain in an unreacted state, which may be oxidized by oxygen in the atmosphere, thereby causing the cured product to be colored. Therefore, such coloration can be prevented by mixing an antioxidant with the low dielectric constant insulating coating composition of the present invention as needed.

As the antioxidant, known substances can be used, for example, 2,6-di-tert-butyl-4-methylphenol, 2,5-di-tert-amylhydroquinone, 2,5-di-tert-butylhydroquinone, 4,4'-butylenebis(3-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), etc. These components can be used alone or in combination of two or more.

Furthermore, when the antioxidant is used, the amount thereof is not particularly limited, and is generally 1 to 10,000 ppm relative to the total mass of the above-mentioned components (A) and (B), and is particularly preferably about 10 to 1,000 ppm. By setting the amount within the above-mentioned range, the antioxidant capacity can be fully exerted, and a cured product with excellent optical properties can be obtained without coloring, whitening, oxidation degradation, etc.

[Inorganic filler] In order to adjust the viscosity of the low dielectric constant insulating coating composition of the present invention and the hardness of the cured product obtained from the low dielectric constant insulating coating composition of the present invention, or to improve the strength, or to make the dispersion of the phosphor better, inorganic fillers such as nanosilica, fused silica, crystalline silica, titanium oxide, nanoalumina, and aluminum oxide may be added.

When an inorganic filler is used, the amount thereof is preferably 5 to 500 parts by mass, more preferably 10 to 200 parts by mass, relative to 100 parts by mass of the total of the above-mentioned components (A) and (B). If such an amount is used, the low dielectric constant insulating coating composition of the present invention will be easy to handle, and the hardness and strength of the cured product will be as desired.

[Adhesion enhancer] An adhesion enhancer can be formulated in the low dielectric constant insulating coating composition of the present invention. Examples of the adhesion enhancer include silane coupling agents or oligomers thereof, polysiloxanes having the same reactive groups as silane coupling agents, and the like.

The adhesion promoter is preferably a silane coupling agent having a compound represented by the following general formula (4) and an allyl isocyanurate structure as an organic functional group. (In general formula (4), s is an integer of 1 to 3, t is an integer of 0 to 3, and u is an integer of 0 to 3, but s+t+u is an integer of 4 to 5. The arrangement of the siloxane units in parentheses is in any order.)

As the silane coupling agent having an allyl isocyanurate structure as an organic functional group, there can be exemplified a compound represented by the following general formula (5). However, R and R' in the general formula (5) are only applicable to the following general formula. (In the general formula (5), at least one R' is an allyl group, and the others are hydrogen atoms, alkyl groups, cycloalkyl groups, aryl groups, heteroaryl groups, non-aromatic heterocyclic groups, ( _CH2 ) _3Si (OR) ₃ or allyl groups, and R is an alkyl group, cycloalkyl group, aryl group, heteroaryl group, non-aromatic heterocyclic group or allyl group.)

In the above general formula (5), R is preferably a C1-4 alkyl group, more preferably a methyl group or an ethyl group. R' is preferably (CH ₂ ) ₃ Si(OR) ₃ or an allyl group.

Specific examples of the silane coupling agent having an allyl isocyanurate structure include X-12-1290 (manufactured by Shin-Etsu Chemical Co., Ltd.) and a compound represented by the following formula.

Specific examples of the adhesion improver include those represented by the following formula, but are not limited thereto. The adhesion improver may be a commercially available product.

Adhesion enhancers are arbitrary components that are added to the composition in order to enhance the adhesion of the substrate of the low dielectric constant insulating coating composition of the present invention and its cured product. Here, the substrate refers to metal materials such as gold, silver, copper, and nickel, ceramic materials such as aluminum oxide, aluminum nitride, and titanium oxide, and polymer materials such as silicone resins and epoxy resins. Adhesion enhancers can be used alone or in combination of two or more.

When the adhesive enhancer is used, the amount thereof is preferably 1 to 30 parts by mass, more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the total of the above-mentioned components (A) and (B). If such an amount is used, the low dielectric constant insulating coating composition of the present invention and its cured product will effectively improve the adhesion to the substrate and will not easily cause coloring.

[Others] In addition, in order to ensure the applicable period, addition reaction control agents such as 1-ethynylcyclohexanol and 3,5-dimethyl-1-hexyn-3-ol can be prepared.

Furthermore, a light stabilizer can be used to impart resistance to light degradation caused by light energy such as sunlight and fluorescent lamps. As the light stabilizer, a hindered amine stabilizer that can capture free radicals generated in photooxidative degradation is suitable. By using it together with an antioxidant, the antioxidant effect will be further improved. Specific examples of light stabilizers include bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 4-benzoyl-2,2,6,6-tetramethylpiperidine, etc.

In the low dielectric constant insulating coating composition of the present invention, the total amount of components (A), (B) and (C) is preferably 50 to 100 mass%, more preferably 80 to 100 mass%, and further preferably 90 to 100 mass%. In addition, the low dielectric constant insulating coating composition of the present invention can be manufactured by mixing the above-mentioned components uniformly.

The low dielectric constant insulating coating composition of the present invention is one containing the above-mentioned components, but it is still unknown and unexpected that such a composition can give a cured product having both excellent mechanical strength and low dielectric properties (dielectric constant and dielectric loss tangent) as described below. For example, as mentioned above, Patent Document 2 describes a curable composition containing a compound having three or more hydrogen atoms bonded to silicon atoms in one molecule, an organic siloxane having two or more alkenyl groups in one molecule, and a silane hydrogenation catalyst, but its use is to be used as a curable composition for a sealing material for white LEDs that requires heat resistance. In the above literature, it is believed that the hardening composition has high hardness, mechanical hardness and crack resistance and can provide a hardened material with excellent light transmittance and gas barrier properties in the short wavelength region, but the literature does not mention the dielectric properties of the hardened material at all.

The following techniques are known for low dielectric constant silicone coating compositions. 1) Using the fact that fine pores are generated inside the layer, the fine pores are generated inside the layer by coating and heating the silicone composition, and the film is crosslinked by condensation of residual -OH groups of the silicone resin and by pyrolysis of the "sacrificial" silicone oil. The silicone resin is formed by dissolving a silicone resin having methyl and phenyl groups and polydimethylsiloxane having α,ω-hydroxylated ends in a solvent. Silsesquioxane having epoxy groups is provided by fine pores distributed throughout the entire volume of the film (Japanese Patent Publication No. 2009-505811). 2) A cured product with a low dielectric constant is obtained by curing a composition including a silsesquioxane having an epoxy group and a curing agent (Japanese Patent Publication No. 2007-332211). 3) A low dielectric constant material (having a structure in which a space is formed at the interface between the silicone polymer and the solid additive) is obtained by dispersing a solid additive in a silicone polymer, and the cured product can achieve a lower dielectric constant than conventional materials (Japanese Patent Publication No. 2010-003761).

In the past, in order to obtain a silicone coating with a low dielectric constant, pores (voids) were set in the coating or cage-shaped silsesquioxane was used, so the density of the coating itself was reduced, and a high hardness coating could not be obtained. In addition, its dielectric constant and dielectric loss tangent still cannot meet the characteristics required as a material with low transmission loss in the gigahertz high frequency region.

Generally speaking, it is known that in the GHz band, the dipole generated by polarization will respond to the electric field and induce dielectricity. Therefore, in order to achieve low dielectric properties in the GHz band, it is important to reduce polarization in the structure. The dielectric constant can be expressed by the following Clausius-Mossotti equation, with molar polarization and molar volume as its factors. Based on this, reducing polarization and increasing molar volume become the key points in low dielectric constant.

Dielectric constant = [1+2(ΣPm/ΣVm)]/[1-(ΣPm/ΣVm)] (Pm: molar polarizability of atomic group; Vm: molar volume of atomic group)

In addition, the dielectric loss tangent (tanδ) is the delay of the dielectric response to the AC electric field, and the relaxation of the dipole orientation in the GHz band becomes the main cause. Therefore, in order to reduce the dielectric loss tangent, it is considered that there is a method to make the dipole disappear (make it a nearly non-polar structure). Therefore, from the perspective of low dielectric properties, the coating seeks the following conditions: reduce polarization from its structure and minimize dipoles (make it a nearly non-polar structure).

In this regard, the addition-curing curing composition described in Patent Document 2 has residual silanol groups derived from SiH groups (which will cause polarization) and there is a concern that the dielectric loss tangent will be reduced, so it is completely unpredictable that it can obtain a low dielectric constant insulating coating composition. In addition, the above-mentioned curing composition can give a hardened material with high hardness, mechanical strength and crack resistance, so it is completely unpredictable that the density of the coating is high and the dielectric constant becomes low. The present invention is contrary to such a prediction. The inventors have found that the hardened material obtained by hardening can have both high mechanical strength and low relative dielectric constant and dielectric loss tangent, thereby achieving the above characteristics for the first time.

[Hardened product] The low dielectric constant insulating coating composition of the present invention is cured to obtain the cured product of the present invention. The cured product has excellent mechanical strength and low relative dielectric constant and dielectric loss tangent. There is no particular restriction on the curing conditions of the low dielectric constant insulating coating composition of the present invention, but preferably the conditions are set to 60 to 180°C and 5 to 180 minutes.

The cured product obtained by curing the low dielectric constant insulating coating composition of the present invention preferably has a relative dielectric constant of 3.0 or less and a dielectric loss tangent of 0.01 or less at 10 GHz. As long as it is within this range, the high-frequency dielectric properties are excellent. The lower limits of the relative dielectric constant and dielectric loss tangent of the cured product at 10 GHz are both better, and there is no special limitation. For example, the relative dielectric constant can be 1.5 or more, and the dielectric loss tangent can be 0.0002 or more. Furthermore, the relative dielectric constant and dielectric loss tangent of the cured product at 10 GHz can be measured by the cavity resonant cavity method in accordance with Japanese industrial standard JIS C2565. For example, you can use a cavity resonant cavity dielectric constant measuring device (manufactured by AET Co., Ltd.) to measure the relative dielectric constant and dielectric loss tangent of a 0.3 mm thick hardened material at 10 GHz.

The mechanical strength (hardness, cutting elongation) of the hardened material can be measured as follows. (Hardness) Using a hardened material of a specific thickness, measure the hardness (Shore D) at 23°C in accordance with ASTM D 2240. (Cutting elongation) Using a hardened material of a specific thickness, measure at 23°C in accordance with Japanese Industrial Standard JIS-K-6249.

The low dielectric constant insulating coating composition of the present invention is applied directly or via other layers to various substrates, components, etc., and then the composition is cured to form an insulating coating layer. In addition, the cured product obtained by curing the low dielectric constant insulating coating composition of the present invention has transparency and is therefore suitable for use as a display device. [Example]

The present invention is specifically described below by showing examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the symbols representing the siloxane unit are as follows. M ^Vi :(CH ₂ =CH)(CH ₃ ) ₂ SiO _1/2 M ^ViΦ :(CH ₂ =CH)(C ₆ H ₅ )(CH ₃ )SiO _1/2 D ^2Φ :(C ₆ H ₅ ) ₂ SiO _2/2

The viscosity at 25°C was measured using a B-type rotational viscometer in accordance with Japanese Industrial Standard JIS-K7117-1:1999.

[Synthesis Example 1] Preparation of (A) Components In a 1-liter four-necked flask equipped with a stirrer, a cooling tube, a dropping funnel, and a thermometer, 262.8 g (1.35 mol) of 1,4-bis(dimethylsilyl)benzene (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.12 g of 5% platinum carbide powder (manufactured by N.E.Chemcat Co., Ltd.) were added, and then heated to 85°C using an oil bath. 28.0 g (0.15 mol) of trivinylphenylsilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was dripped into it. After the dripping was completed, the mixture was stirred at 90-100°C for 5 hours. After the stirring was completed, the temperature was returned to 25°C, and 2.9 g of activated carbon was added and stirred for 1 hour. After stirring, the mixture was filtered and then concentrated under reduced pressure to obtain 99.7 g of the addition reaction product (colorless and transparent, yield 87%, concentration at 25°C: 30 Pa·s).

According to the results of analyzing the reaction product by ¹ H-NMR, GPC, etc., the product is a mixture of compounds having structures represented by the following formulas (a) to (c), (f), and the ratio of each compound is (a): (b): (c): (f) = 55: 25: 10: 10 (mol %). In addition, the aforementioned compounds are compounds having 3 or more SiH groups in one molecule, and the content ratio of SiH groups in the aforementioned mixture as a whole is 0.0035 mol/g.

[Example 1] The following components were mixed to obtain a composition: 75 parts by mass of (A) the reaction product obtained in Synthesis Example 1; 114 parts by mass of (B-1) an organopolysiloxane represented by an average unit formula M ^{Vi Φ} ₂ D ^2Φ ₃ , having 0.22 mol of vinyl groups per 100 g, and having a viscosity of 2000 mPa·s at 25°C; 9 parts by mass of (B-2) an organopolysiloxane represented by an average unit formula M ^Vi ₂ D ^2Φ , having 0.50 mol of vinyl groups per 100 g, and having a viscosity of 10 mPa·s at 25°C; (C) a platinum-vinylsiloxane complex in an amount of 3 ppm in terms of platinum metal atoms relative to the total mass of (A), (B-1) and (B-2); 2 parts by mass of a compound represented by the following formula (6) as an adhesion enhancer; and 0.07 parts by mass of 1-ethynylcyclohexanol as a reaction control agent. The composition was poured into a 2 mm and 0.3 mm thick gold frame and heated at 150°C for 4 hours to obtain a hardened material. The SiH/Vi ratio (SiH group/aliphatic unsaturated group) in the above composition was 0.89.

[Example 2] The following components are mixed to obtain a composition: 75 parts by mass of (A) the reaction product obtained in Synthesis Example 1; 123 parts by mass of (B-1) an organopolysiloxane represented by an average unit formula M ^ViΦ ₂ D ^2Φ ₃ and having 0.22 mol of vinyl groups per 100 g and a viscosity of 2000 mPa·s at 25°C; (C) a platinum-vinylsiloxane complex in an amount of 3 ppm in terms of platinum metal atoms relative to the total mass of (A) and (B-1); 2 parts by mass of a compound represented by the above formula (6) as an adhesion enhancer; and 0.07 parts by mass of 1-ethynylcyclohexanol as a reaction control agent. The composition was poured into a gold frame having a thickness of 2 mm and 0.3 mm, and heated at 150°C for 4 hours to obtain a hardened product. The SiH/Vi ratio in the above composition was 0.97.

[Comparative Example 1] As a silicone material with a methyl substituent, a methyl silicone resin curable composition (trade name: KER-2300, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (25°C): 5000 mPa・s) was poured into a 2 mm and 0.3 mm thick gold frame in the same manner as in Example 1, and heated at 150°C for 2 hours to obtain a cured product.

<Performance Evaluation Method> The performance of the hardened products obtained from the above-mentioned embodiments and comparative examples was evaluated according to the following method. The evaluation results are shown in Table 1.

(1) Appearance Visually observe the appearance of the 2 mm thick hardened product.

(2) Hardness Three 2 mm thick hardened sheets were stacked to form a 6 mm thick sheet, and the hardness (Shore D) was measured at 23°C in accordance with ASTM D 2240.

(3) Elongation (Cutting elongation) Using a 2 mm thick hardened material, the cutting elongation was measured at 23°C in accordance with Japanese Industrial Standard JIS-K-6249.

(4) Relative dielectric constant and (5) dielectric loss tangent Using a cavity-type resonant cavity dielectric constant measuring device (manufactured by AET Co., Ltd.), the relative dielectric constant and dielectric loss tangent of a 0.3 mm thick hardened material at 10 GHz were measured.

[Table 1] Embodiment 1 Embodiment 2 Comparison Example 1 Appearance Colorless and transparent Colorless and transparent Colorless and transparent hardness D55 D70 D50 Elongation(%) 200 140 50 Relative dielectric constant 2.70 2.70 2.75 Dielectric loss tangent (tanδ) 0.002 0.002 0.020

From the above results, it can be seen that the compositions of Examples 1 and 2 have appropriate viscosity and excellent workability when applied to a substrate. In addition, the cured products obtained from Examples 1 and 2 have high hardness and high strength, a relative dielectric constant of less than 3.0 and a dielectric loss tangent of less than 0.01 at 10 GHz, and excellent high-frequency dielectric properties.

On the other hand, it can be seen that the methyl silicone resin-based cured product of Comparative Example 1 has insufficient strength and a large dielectric loss tangent, and cannot satisfy high-frequency characteristics.

The present specification includes the following aspects. [1] A low dielectric constant insulating coating composition comprising the following components (A), (B) and (C): (A) an addition reaction product, which is an addition reaction product of an organic silicon compound represented by the following general formula (1) and an organic silicon compound represented by the following general formula (2), and has three or more SiH groups in one molecule, (In the general formula (1), R ¹ is independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms), (In general formula (2), ^R2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and ^R3 is a single bond or unsubstituted divalent hydrocarbon group having 1 to 4 carbon atoms); (B) an organic siloxane compound having two or more alkenyl groups in one molecule; and, (C) a hydrosilylation catalyst. [2] The low dielectric constant insulating coating composition as described in [1], wherein the aforementioned ^R1 is a phenyl group and the aforementioned ^R2 is a methyl group or a phenyl group. [3] The low dielectric constant insulating coating composition as described in [1] or [2], wherein the aforementioned component (B) is a compound represented by the following general formula (3), (In general formula (3), ^R4 is independently an unsubstituted or substituted monovalent alkyl group, ^R5 is independently a methyl group or a phenyl group, a is an integer from 0 to 50, and b is an integer from 0 to 100; however, when a is 0, ^R5 is a phenyl group and b is 1 to 100; the arrangement of the siloxane units in parentheses is in any order.) [4] A cured material characterized by being formed by curing the low dielectric constant insulating coating composition described in any one of [1] to [3]. [5] A cured material as described in [4], wherein the dielectric constant at 10 GHz is less than 3.0 and the dielectric loss tangent is less than 0.01. [6] A display device characterized by having a layer composed of the cured material described in [4] or [5].

Furthermore, the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are illustrative only, and all those having substantially the same configuration as the technical concept described in the scope of the patent application of the present invention and being able to exert the same function and effect are all included in the technical scope of the present invention.

without

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Claims (6)

A low dielectric constant insulating coating composition comprises the following components (A), (B) and (C): (A) an addition reaction product, which is an addition reaction product of an organic silicon compound represented by the following general formula (1) and an organic silicon compound represented by the following general formula (2), and has three or more SiH groups in one molecule, (In the general formula (1), R ¹ is independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms), (In the general formula (2), ^R2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and ^R3 is a single bond or an unsubstituted divalent hydrocarbon group having 1 to 4 carbon atoms); (B) an organosiloxane compound having two or more alkenyl groups in one molecule; and, (C) a hydrosilylation catalyst. The low dielectric constant insulating coating composition as described in claim 1, wherein the aforementioned R ¹ is a phenylene group, and the aforementioned R ² is a methyl group or a phenyl group. The low dielectric constant insulating coating composition as described in claim 1 or claim 2, wherein the component (B) is a compound represented by the following general formula (3): (In general formula (3), ^R4 is independently a substituted or unsubstituted monovalent alkyl group, ^R5 is independently a methyl group or a phenyl group, a is an integer from 0 to 50, and b is an integer from 0 to 100; however, when a is 0, ^R5 is a phenyl group and b is 1 to 100; the arrangement of the siloxane units in parentheses is in any order). A cured product is characterized by being formed by curing the low dielectric constant insulating coating composition described in any one of claims 1 to 3. The hardened material as claimed in claim 4, wherein the dielectric constant at 10 GHz is less than 3.0 and the dielectric loss tangent is less than 0.01. A display device is characterized by having a layer composed of the hardened material described in claim 4 or claim 5.