Heat-insulating silicone composition and method for producing heat-insulating cured product using the composition

Abstract

This invention provides a heat-insulating silicone composition exhibiting low adhesion and improved flexibility at high temperatures. The composition comprises: (A) an organopolysiloxane containing, within one molecule, alkenyl groups bonded to at least two silicon atoms; (B) an organohydrogen polysiloxane containing 0.0001 to 0.005 moles / gram of hydrogen atoms bonded to silicon atoms; (C) an organic resin hollow filler; and (D) an addition reaction catalyst. The content of component (C) is 5 to 25 parts by mass relative to 100 parts by mass of the total amount of component (A) and component (B), the content of component (D) is 0.05 to 1.8 parts by mass, and the mole ratio [Si-H groups / alkenyl groups] of the total amount of Si-H groups in the entire heat-insulating silicone composition to the total amount of alkenyl groups bonded to silicon atoms in component (A) is 0.5 to 1.0.

Description

[Technical Field]

[0001] This invention relates to a heat-insulating silicone composition and a method for preparing a heat-insulating cured product using the composition. [Previous Technology]

[0002] Silicone rubber adhesive compositions are used as protective agents for bonding, fixing, heat resistance, weather resistance, electrical insulation, etc., in components such as various electrical and electronic components, automotive components, and various computer-related components in PCs and mobile devices.

[0003] PTL 1 discloses a low-density silicone rubber adhesive composition, which is a low-density adhesive with cushioning and heat insulation properties. This adhesive is obtained by adding an adhesive additive to a silicone rubber composition containing a hollow filler formed from an organic resin.

[0004] Citation List

[0005] Patent Documents

[0006] PTL 1: Japanese Patent No. 5115716 [Summary of the Invention]

[0007] For example, components such as battery casings may expand in high-temperature operating environments. The cured product of the silicone rubber adhesive composition of PTL 1 has high adhesion. Therefore, when this cured product is placed around an expandable component, the cured product may restrict the expansion force and damage the component.

[0008] The present invention provides a heat-insulating silicone composition having low adhesion and improved softness at high temperature, and a method for preparing a heat-insulating cured product using the heat-insulating silicone composition. Solution to Problem

[0009]

[0010] The heat-insulating silicone composition of the present invention comprises: component (A), which is an organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms within one molecule; component (B), which is an organohydrogen polysiloxane containing 0.0001 moles / g or more and 0.005 moles / g or less of hydrogen atoms bonded to silicon atoms; component (C), which is a hollow filler formed from an organic resin; and component (D), which is an addition reaction catalyst. When the total amount of components (A) and (B) is 100 parts by mass, the content of component (C) may be 5 parts by mass or more and 25 parts by mass or less, the content of component (D) may be 0.05 parts by mass or more and 1.8 parts by mass or less, and the molar ratio of the total amount of Si-H groups contained in the entire thermal insulation silicone composition to the total amount of alkenyl groups bonded to silicon atoms in component (A) [Si-H groups / alkenyl groups] may be 0.5 or more and 1.0 or less.

[0011] The molar ratio [Si-H group / alkenyl group] is preferably 0.5 or more and 0.9 or less.

[0012] Inorganic substances may adhere to at least a portion of the surface of component (C).

[0013] In component (C), the inorganic material may be subjected to surface treatment that imparts compatibility or surface treatment that imparts dispersibility.

[0014] Component (C) may have a true density of 0.2 g / cm³ or less.

[0015] Component (C) may have an average particle size of 150 micrometers or less, and more preferably 30 micrometers or more and 80 micrometers or less.

[0016] The heat-insulating silicone composition may further include a component (E), which is a silicone resin having at least one alkenyl group in the molecule and having an average molecular weight of 1,000 or more and 10,000 or less, preferably 1,400 or more and 4,000 or less, and more preferably 1,400 or more and 2,500 or less.

[0017] Preferably, the heat-insulating silicone composition does not include silica.

[0018] The heat-insulating silicone composition preferably does not include adhesive additives.

[0019] The viscosity of the uncured insulating silicone composition at 25°C may be 10,000 mPa·s or less, and more preferably 1,000 mPa·s or more and 4,000 mPa·s or less. In the case where the insulating silicone composition is a two-component mixture comprising a first liquid and a second liquid, the viscosity of each of the first and second liquids at 25°C may be 10,000 mPa·s or less, and more preferably 1,000 mPa·s or more and 4,000 mPa·s or less. When the first and second liquids are mixed, the viscosity at 25°C before curing begins or during the initial stage of curing may be 10,000 mPa·s or less, and more preferably 1,000 mPa·s or more and 4,000 mPa·s or less.

[0020] (Measurement Method)

[0021] The viscosity of the heat-insulating silicone composition at 25°C was measured according to JIS K 7117-2. For example, the uncured heat-insulating silicone composition was placed between a cone with a diameter of 25 mm and rotated at an angle of 1° or 2° and a fixed plate, and its viscosity was measured using a viscometer at a shear rate of 10 (1 / s) and a gap of 0.106 mm.

[0022] The heat-insulating cured product obtained by curing the heat-insulating silicone composition may have a thermal conductivity of 0.2 W / mK or less, preferably 0.1 W / mK or more and 0.18 W / mK or less, and more preferably 0.12 W / mK or more and 0.15 W / mK or less.

[0023] (Measurement Method)

[0024] The thermal conductivity of the heat-insulating cured product at 25°C was measured according to ISO 22007-2. For example, the heat-insulating silicone composition was cured at 100°C for 30 minutes to produce a test piece with a diameter of 40 mm and a height of 10 mm, and then a sensor was clamped between the two resulting test pieces to measure its thermal conductivity.

[0025] The heat-insulating cured product obtained by curing the heat-insulating silicone composition may have a hardness of 10 or more and 40 or less (penetration hardness).

[0026] (Measurement Method)

[0027] The penetration of the heat-insulating cured product at 23°C is measured according to ASTM D 2240. For example, the penetration of a heat-insulating cured product obtained by curing the heat-insulating composition at 100°C for 30 minutes is measured in a 60 ml container. "Penetration" is indicated by the length of the portion of the sample penetrated by a standard steel needle at a constant temperature. The penetration length is measured while holding a 100 g load for 5 seconds, and the measured penetration depth is expressed in increments of 1 / 10 mm.

[0028] The heat-insulating cured product obtained by curing the heat-insulating silicone composition may have a specific gravity of 0.7 or less.

[0029] The heat-insulating cured product obtained by curing the heat-insulating silicone composition may have a density of 0.5 g / mL or more and 0.68 g / mL or less, and preferably 0.52 g / mL or more and 0.67 g / mL or less.

[0030] (Measurement Method)

[0031] The density of the heat-insulating cured product at 23°C was measured according to JIS K 6249. For example, the density of a test specimen obtained by curing the heat-insulating silicone composition at 100°C for 30 minutes was measured by the underwater displacement method.

[0032] The heat-insulating cured product obtained by curing the heat-insulating silicone composition may have a tensile strength of 50 kPa or more and 400 kPa or less.

[0033] (Measurement Method)

[0034] The tensile strength of the heat-insulating cured product at 25°C was measured according to JIS K 6251. For example, a 2 mm thick sheet obtained by curing a heat-insulating silicone composition at 100°C for 30 minutes was stamped into a No. 3 dumbbell shape, and the breaking strength and elongation were measured using a tensile testing machine when stretched at a tensile speed of 500 mm / min.

[0035] In the heat-insulating silicone composition, the floatability of component (C) relative to other components may be 40% or more and 70% or less, and preferably 40% or more and 65% or less.

[0036] (Measurement Method)

[0037] The buoyancy of the filler is determined by the interfacial position between the liquid phase (silicone phase) and the filler phase (component (C) phase) after the uncured insulating silicone composition has been left to stand for a specific period of time. For example, the material (either the first liquid or the second liquid when the composition is divided into a first liquid and a second liquid) is poured into a 50 ml container with a diameter of 35 mm and a height of 78 mm to a filling height of 55 mm from the bottom, and stored under high temperature conditions for a specified period of time (e.g., one week at 50°C). Then, the interfacial position between the silicone phase and the filler phase is measured using tools such as a ruler. The buoyancy of the filler component is determined by the interfacial position and the filling amount of the filler component. The volume fraction of the blending amount of component (C) in the first liquid or the second liquid relative to the blending amount of other components is calculated. For example, it is assumed that the volume fraction (i.e., the liquid phase of component (C): other components) is 4:6. Then, the theoretical height H0 of the liquid phase is obtained by multiplying the volume fraction of the liquid phase (=6 / 10) by the filling height (=55 mm). The height H1 of the liquid phase is measured with a ruler after being stored at high temperature for a specified period of time. For example, suppose the measured height H1 (interface position) is 16.5 mm (the liquid phase composition of component (C): other components is 7:3). The buoyancy can be expressed as H1 / H0×100% (in the example above, H1 / H0×100%=16.5 / 33×100%=50%).

[0038] The strength of component (C) may be 2 N or less.

[0039] (Measurement Method)

[0040] The strength of the filler component (component (C)) floating on the sample surface after the buoyancy evaluation test is measured. For example, the maximum load value is measured using a compression testing machine when a spherical compression clamp with a diameter of 12.7 mm is pressed onto the sample at a compression rate of 240 mm / min to penetrate the sample.

[0041] Compared with before heating, when the heat-insulating cured product obtained by curing the heat-insulating silicone composition is heated at 190 to 210°C for 1 to 2.5 hours, the volume change rate after heating can be 15% or more and 34% or less of volume shrinkage (volume change rate of -34% or more and -15% or less).

[0042] (Measurement Method)

[0043] The volume change rate of a sample heated at a specified temperature (e.g., 200°C) for a specified time (e.g., 2 hours) using a heating device (e.g., an oven) was measured. For example, the weight and density of a test piece with a diameter of 40 mm and a height of 10 mm obtained by curing a heat-insulating silicone composition at 100°C for 30 minutes were measured to calculate the volume (before heat shrinkage). The weight and density of a test piece heated in an oven at 200°C for 2 hours and then cooled to room temperature were measured to calculate the volume (after heat shrinkage). The volume change rate was calculated from the difference between the volume before heating and the volume after heating.

[0044] Volume change rate = {(Volume after heat shrinkage) – (Volume before heat shrinkage)} / (Volume before heat shrinkage) × 100%

[0045] The method for preparing the heat-insulating cured product obtained by curing the above-mentioned heat-insulating silicone composition includes: potting the heat-insulating silicone composition onto a substrate (filling and coating steps) to form a potting layer; and curing the potting layer at a temperature of 5°C or higher and 100°C or lower, and more preferably 15°C or higher and 50°C or lower.

[0046] (Operation and Effects) (1) Although adhesion is generated by the interaction between Si-H groups and functional groups (-OH groups, etc.) on the surface of the adherend, the amount of organohydrogen polysiloxane in the composition of the present invention (i.e., the density of Si-H groups) is small, and therefore the adhesion is lower than that of the composition disclosed in PTL 1. (2) Although curing is achieved when Si-H groups and Si-olefin groups are bonded and crosslinked to each other by addition reaction, the amount of Si-H in the composition of the present invention is small, and therefore the crosslinking density is low, and the cured product obtained after curing has lower hardness and is softer. (3) Compared with the composition of PTL 1, the heat-insulating silicone composition has lower adhesion and improved good softness, and its cured product shrinks at a certain temperature or higher. (4) When blended with silicone resin, the heat-insulating cured product obtained by curing the heat-insulating silicone composition can have reduced brittleness. (5) When silica is not blended, the insulating silicone composition can have reduced viscosity. (6) Its lower viscosity can improve processability, operability, and potting properties. (7) The compositions of the present invention are used at least as potting compounds and have a certain degree of hardness and adhesion. The cured products of the compositions of the present invention can be satisfactorily peeled off at certain temperatures or higher, and therefore have excellent reprocessing and durability properties. (8) Known electric vehicle battery cells are covered with insulating materials with strong adhesion to prevent damage and fire spread in the event of an explosion. However, this strong adhesion complicates recycling and increases the environmental burden. According to the present invention, an insulating material can be provided that exerts controlled adhesion to the outer sheath of the battery cell in order to improve recycling properties. Reduced adhesion facilitates disassembly and improves resource recovery. The present invention, which helps reduce the environmental burden, is an innovative technology for improving the sustainability of electric vehicle batteries.

Implementation Method

[0047] The insulating silicone composition and the method for preparing an insulating cured product using the insulating silicone composition according to the invention will be described in detail below.

[0048] (Insulating silicone composition)

[0049] The heat-insulating silicone composition is a composition used to form a heat-insulating cured product. Examples of heat-insulating silicone compositions include formulations used as potting compounds for applications such as substrates for specific substrates (e.g., electrical or electronic equipment, circuit chips, automotive components, battery assemblies, etc.).

[0050] The temperature and process for curing the heat-insulating silicone composition are not particularly limited and can be appropriately selected depending on the intended use of the cured product, etc.

[0051] The following will describe in detail the corresponding components of the thermal insulation silicone composition when the curing method of the thermal insulation silicone composition according to the present invention is an addition reaction.

[0052] Component (A): Organopolysiloxane

[0053] Component (A) is the main reagent of the heat-insulating silicone composition and is an organic polysiloxane containing an alkenyl group bonded to at least two silicon atoms within one molecule.

[0054] The molar ratio of the total amount of Si-H groups contained in the entire thermal insulation silicone composition to the total amount of alkenyl groups bonded to silicon atoms in component (A) [Si-H groups / alkenyl groups] is 0.5 or more and 1.0 or less.

[0055] The viscosity and degree of polymerization of component (A) are not particularly limited and can be selected according to the required mixing viscosity of the insulating silicone composition, etc. For example, its viscosity at 25°C can be 10 mPa·s or more and 30,000 mPa·s or less.

[0056] As an organopolysiloxane, one type can be used alone, or two or more types can be used in combination appropriately. The organopolysiloxane is the main component of the heat-insulating silicone composition and has an average of at least two alkenyl groups bonded to silicon atoms within one molecule, preferably 2 to 50 alkenyl groups, and more preferably 2 to 20 alkenyl groups.

[0057] The molecular structure of component (A) is not specifically limited and may be, for example, a linear structure, a partially branched linear structure, a branched structure, a cyclic structure, or a branched cyclic structure. Preferably, component (A) is a substantially linear organopolysiloxane. Specifically, component (A) may be a linear diorganopolysiloxane, wherein the molecular chain is mainly composed of disiloxane repeating units and both ends of the molecular chain are capped with triorganosiloxy groups. Some or all of the ends of the molecular chain, or some of the side chains, may be silanol groups.

[0058] The position of the alkenyl group bonded to the silicon atom in component (A) is not particularly restricted, and component (A) may be an organopolysiloxane having alkenyl groups bonded to the silicon atom at the ends of both molecular chains.

[0059] The advantage of an organopolysiloxane having an alkenyl group at each end of the molecular chain is that the content of alkenyl groups that act as reaction sites for crosslinking reactions is small, and the softness of the cured product obtained by curing the heat-insulating silicone composition is improved.

[0060] In addition to having alkenyl groups at both ends, organopolysiloxanes that also have alkenyl groups in the side chains of the molecular chain can improve the crosslinking density and hardness of the cured product obtained by curing the heat-insulating silicone composition.

[0061] The number of alkenyl groups in one molecule of component (A) can be appropriately determined according to the hardness required for the cured product, the molecular weight of component (A), etc. The number of alkynyl groups in one molecule may be two or more, more preferably two or more and five or fewer, and most preferably two (one alkynyl group at each end of the molecular chain).

[0062] The alkenyl group can be bonded to silicon atoms at the end of the molecular chain, silicon atoms at non-terminal molecular chain sites (in the middle of the molecular chain), or both.

[0063] Component (A) may be a polymer composed of a single type of siloxane unit or a copolymer composed of two or more types of siloxane units.

[0064] The viscosity of component (A) at 25°C is 10 mPa·s or more and 30,000 mPa·s or less, preferably 50 mPa·s or more and 1,000 mPa·s or less, and more preferably 100 mPa·s or more and 500 mPa·s or less.

[0065] In order to adjust the viscosity (mixed viscosity) of the heat-insulating silicone composition before curing, two or more types of organic polysiloxanes with alkenyl groups and different viscosities may also be used in combination.

[0066] Specifically, component (A) is represented by the following general formula (1) in average composition: R1aSiO(4-a) / 2… (1) (in formula (1), R1 is the same or different from each other, and each is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, and a is 1.7 to 2.1, preferably 1.8 to 2.5, and more preferably 1.95 to 2.05).

[0067] In one embodiment, at least two or more of the monovalent hydrocarbon groups represented by R1 are selected from alkenyl groups, such as vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, isobutenyl groups, hexenyl groups, and cyclohexenyl groups. The groups other than these are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 18 carbon atoms. Specifically, the aforementioned R1 is selected from alkyl groups, such as methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tributyl groups, pentyl groups, neopentyl groups, hexyl groups, 2-ethylhexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, and dodecyl groups; cycloalkyl groups, such as cyclopentyl groups, cyclohexyl groups, and cycloheptyl groups; aryl groups, such as phenyl groups, tolyl groups, xylyl groups, biphenyl groups, and naphthyl groups; aralkyl groups, such as benzyl groups, phenethyl groups, phenylpropyl groups, and methylbenzyl groups; and alkyl groups that are halogenated or cyano-substituted, wherein some or all of the hydrogen atoms in the above-mentioned hydrocarbon groups are substituted with halogen atoms, cyano groups, etc., such as chloromethyl groups, 2-bromoethyl groups, 3,3,3-trifluoropropyl groups, 3-chloropropyl groups, and cyanoethyl groups.

[0068] Examples of preferred R1 groups, as the two or more alkenyl groups desired, include vinyl groups, allyl groups, propenyl groups, isopropenyl groups, 2-methyl-1-propenyl groups, 2-methylallyl groups, and 2-butenyl groups. Vinyl groups are particularly preferred. Preferred examples of R1 other than alkenyl groups include methyl groups and phenyl groups, with methyl being particularly preferred. Furthermore, considering the physical properties and economic efficiency of the cured product, it is preferable that 70 mol% or more of R1 is a methyl group, and typically, it is preferable that 80 mol% or more of R1 is a methyl group.

[0069] Specific examples of the molecular structure of component (A) include dimethyl polysiloxanes whose ends are both capped with dimethylvinylsiloxane groups, dimethylsiloxane-methylphenylsiloxane copolymers whose ends are both capped with dimethylvinylsiloxane groups, dimethylsiloxane-methylvinylsiloxane copolymers whose ends are both capped with dimethylvinylsiloxane groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers whose ends are both capped with dimethylvinylsiloxane groups, and dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers whose ends are both capped with trimethylsiloxane groups. Organopolysiloxanes comprising methylsiloxane-methylvinylsiloxane copolymers, siloxane units represented by the formula (CH3)2ViSiO1 / 2, siloxane units represented by the formula (CH3)3SiO1 / 2, and siloxane units represented by the formula SiO4 / 2 (where Vi represents a vinyl group), wherein some or all of the methyl groups in the aforementioned organopolysiloxanes are replaced by alkyl groups such as ethyl or propyl groups, aryl groups such as phenyl or tolyl groups, and haloalkyl groups such as those substituted with 3,3,3-trifluoropropyl groups, and mixtures of two or more of these organopolysiloxanes. From the viewpoint of increasing the elongation at break of the cured product due to the increased molecular chain length, linear diorganopolysiloxanes having a vinyl group at the end of each molecular chain are preferred.

[0070] These diorganopolysiloxanes are commercially available or prepared by methods known to those skilled in the art.

[0071] Component (B): Organohydrogen polysiloxane

[0072] Component (B) is an organohydrogen polysiloxane containing 0.0001 mol / g or more and 0.005 mol / g or less of hydrogen atoms bonded to silicon atoms.

[0073] Component (B) is an organohydrogen polysiloxane containing two or more hydrogen atoms bonded to silicon atoms within a molecule, and is a crosslinking component that forms a cured product through an addition curing reaction between Si-H groups and alkenyl groups.

[0074] The organohydrogen polysiloxane as component (B) is represented by the following average compositional formula (2): [Chemical Formula 2] (in formula (2), R2 is each independently a hydrogen atom, a hydroxyl group, or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that component (B) contains two or more hydrogen atoms bonded to silicon atoms in one molecule, a is an integer of 2 or more, b is an integer of 1 or more, c is an integer of 0 or more, and d is an integer of 0 or more, and the value of a+b+c+d is not particularly limited, provided that the viscosity of component (B) meets the viscosity range described later, and may be 5 or more and 600 or less, but may be 10 or more and 400 or less).

[0075] The viscosity of component (B) at 25°C may be 1 mPa·s or more and 3,000 mPa·s, and preferably 10 mPa·s or more and 1,000 mPa·s or less.

[0076] When R2 bonded to the silicon atom in component (B) is another monovalent hydrocarbon group, specific examples of monovalent hydrocarbon groups include alkyl groups, such as methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, pentyl groups, neopentyl groups, hexyl groups, 2-ethylhexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, and dodecyl groups; cycloalkyl groups, such as cyclopentyl groups, cyclohexyl groups, and cycloheptyl groups; aryl groups, such as phenyl groups, toluene groups, etc. The hydrocarbon group includes methyl, xyl, biphenyl, and naphthyl groups; aralkyl groups, such as benzyl, phenethyl, phenylpropyl, and methylbenzyl groups; and substituted hydrocarbon groups, wherein some or all of the hydrogen atoms in the above hydrocarbon groups are replaced by halogen atoms, cyano groups, etc., such as chloromethyl, 2-bromoethyl, 3,3,3-trifluoropropyl, 3-chloropropyl, chlorophenyl, dibromophenyl, tetrachlorophenyl, difluorophenyl, β-cyanoethyl, γ-cyanopropyl, and β-cyanopropyl groups. Particularly preferred monovalent hydrocarbon groups are methyl and phenyl groups.

[0077] Component (B) may also include those having -SiOH groups at a portion of the end of the molecular chain. In this case, the number of silicon atoms having OH groups is less than 5% and preferably less than 2% of the total number of terminal silicon atoms in the entire organohydrogen polysiloxane in component (B). When this ratio meets the conditions mentioned above, the addition reaction proceeds sufficiently and a cured film of sufficient quality can be obtained.

[0078] The hydrogen content (H content) of component (B) is 0.0001 mol / g or more and 0.005 mol / g or less, preferably 0.0002 mol / g or more and 0.005 mol / g or less, more preferably 0.0003 mol / g or more and 0.005 mol / g or less, and even more preferably 0.0004 mol / g or more and 0.005 mol / g or less.

[0079] Component (B) may be used as a crosslinking agent. The crosslinking agent is preferably an organohydrogen polysiloxane having five or more hydrosilyl groups, and may be an organohydrogen polysiloxane having ten or more and eighteen or fewer hydrosilyl groups. The organohydrogen polysiloxane as a crosslinking agent has at least two hydrosilyl groups present in its side chain. The number of hydrosilyl groups at the end of the molecular chain may be zero or more and two or fewer, and from an economic point of view, two is preferred. The molecular structure of the organohydrogen polysiloxane may be any of linear, cyclic, branched, and three-dimensional network structures. The position of the silicon atoms bonded by the hydrogen atoms is not particularly limited, and may be at the end of the molecular chain, at non-terminal molecular chain sites (in the middle of the molecular chain), or in the side chain. Other conditions in the organohydrogen polysiloxanes acting as crosslinking agents, the type of organic groups other than the hydrogenated silyl groups, the bond positions, the degree of polymerization, the structure, etc., are not particularly restricted. Two or more types of organohydrogen polysiloxanes can be used in combination.

[0080] The content of component (B) is, for example, 30 or more and 35 or less, relative to the total amount of 100 parts by mass of component (A) and component (B).

[0081] The hydrogenated silyl group in component (B) may be present at the ends of the molecular chain, may be present in the side chain, or may be present simultaneously at the ends of the molecular chain and in the side chain. Preferably, a mixture of an organohydrogen polysiloxane having only one hydrogenated silyl group at the ends of each molecular chain and an organohydrogen polysiloxane having hydrogenated silyl groups only in the side chains of the molecular chain is used.

[0082] From the viewpoint of improving heat resistance, component (B) may include an organohydrogen polysiloxane having at least one aromatic group within the molecule. For economic reasons, the aromatic group is preferably a phenyl group. Organohydrogen polysiloxanes containing aromatic groups and organohydrogen polysiloxanes without aromatic groups may be used in combination.

[0083] Component (C): Hollow filler formed from organic resin

[0084] Component (C) is a hollow filler formed from organic resin.

[0085] The organic resin used for the hollow filler formed from the organic resin can be selected from a variety of polymers, such as polymers of vinylidene chloride, polymers of acrylonitrile, polymers of methacrylonitrile, polymers of acrylates and polymers of methacrylates; and copolymers selected from two or more of these monomer units.

[0086] The average particle size of the hollow filler formed from organic resin may be 15 micrometers or more and 150 micrometers or less, preferably 20 micrometers or more and 100 micrometers or less, and even more preferably 20 micrometers or more and 80 micrometers or less. The average particle size is a value measured by laser diffraction using a fine distribution measuring device, which is the cumulative weight mean (D50) or median diameter.

[0087] Component (C) or component (C) with attached inorganic matter has a true specific gravity of 0.1 or more and 0.3 or less, preferably 0.11 or more and 0.25 or less, more preferably 0.12 or more and 0.20 or less, and even more preferably 0.12 or more and 0.18 or less. Controlling the specific gravity of the packing material can suppress the separation (floating) of the packing material in the composition (first liquid or second liquid).

[0088] The content of component (C) is 5 parts or more and 25 parts or less, or 7 parts or more and 22 parts or less, more preferably 8 parts or more and 20 parts or less, more preferably 8 parts or more and 16 parts or less, and even more preferably 8 parts or more and 14 parts or less, relative to 100 parts by mass of component (A) and the total amount of component (B).

[0089] Component (C) may have an inorganic substance attached to at least a portion of its surface. Examples of inorganic substances include calcium carbonate, zinc oxide, hydroxyapatite, and magnesium silicate hydrate.

[0090] In component (C), inorganic substances may be subjected to surface treatments that impart compatibility or dispersibility. The surface treatments that impart compatibility or dispersibility may be performed using organic substances such as fatty acids and resin acids.

[0091] Encapsulating hollow fillers made of organic resin with inorganic substances can suppress the separation (floating) of fillers in the insulating silicone composition (first liquid or second liquid). Since fillers may float during storage, the low-viscosity first liquid or second liquid of the insulating silicone composition suppresses filler floating by setting the specific gravity of the filler and performing surface treatment.

[0092] Component (D): Addition reaction catalyst

[0093] The addition reaction catalyst of component (D) is a catalyst that promotes the addition curing reaction between the alkenyl groups bonded to silicon atoms in component (A) and the hydrogen atoms bonded to silicon atoms in component (B), and is a catalyst known to those skilled in the art. Examples of component (D) include platinum group metals such as platinum, rhodium, palladium, osmium, iridium, and ruthenium, and catalysts in which any of the aforementioned metals are supported by particulate carrier materials (e.g., activated carbon, alumina, and silicon oxide).

[0094] In addition, specific examples of component (D) include platinum halide, platinum-olefin complex, platinum-alcohol complex, platinum-alkoxide complex, platinum-vinylsiloxane complex, dicyclopentadiene-platinum dichloride, cyclooctadiene-platinum dichloride and cyclopentadiene-platinum dichloride.

[0095] Furthermore, from an economic point of view, metal compound catalysts other than the platinum group metals mentioned above can also be used as component (D). Examples of iron catalysts for hydrogenation silanization include iron-carbonyl complex catalysts, iron catalysts having a cyclopentadienyl group as a ligand, iron catalysts having a terpyridyl ligand or a combination of a terpyridyl ligand and a bis(trimethyl)silylmethyl group, iron catalysts having a bisiminopyridine ligand, iron catalysts having a bisiminoquinoline ligand, iron catalysts having an aryl group as a ligand, iron catalysts having a cyclic or acyclic olefinic group with an unsaturated group, and iron catalysts having a cyclic or acyclic olefinic group with an unsaturated group. Other examples of catalysts for hydrogenation silanization include cobalt catalysts, vanadium catalysts, ruthenium catalysts, iridium catalysts, samarium catalysts, nickel catalysts, and manganese catalysts.

[0096] Regarding the concentration of the catalyst metal element, the blending amount of component (D) relative to the total mass of the insulating silicone composition is preferably in the range of 0.5 ppm or more and 1,000 ppm or less, more preferably 1 ppm or more and 500 ppm or less, and even more preferably 1 ppm or more and 100 ppm or less, but the effective amount is used according to the curing temperature and curing time desired for the application. If the blending amount is less than 0.5 ppm, the addition reaction becomes significantly slower. If the blending amount exceeds 1,000 ppm, it is economically unfavorable due to increased cost.

[0097] The content of component (D) may be 0.05 parts by mass or more and 1.8 parts by mass or less, relative to 100 parts by mass of component (A) and the total amount of component (B), preferably 0.08 parts by mass or more and 1.6 parts by mass or less.

[0098] Component (E): Silicone resin

[0099] Component (E) is a silicone resin having at least one alkenyl group in the molecule and having an average molecular weight of 1,000 or more.

[0100] The silicone resin may be a modified silicone resin, and may be a mixture of a resin without alkenyl groups and an organic polysiloxane containing alkenyl groups.

[0101] Examples of silicone resins include methyl silicone resins and methyl phenyl silicone resins. Examples of modified silicone resins include alkyd modified silicone resins, epoxy modified silicone resins, acrylic modified silicone resins, and polyester modified silicone resins.

[0102] Component (E) may be the same as the alkenyl group-containing organic polysiloxane of component (A).

[0103] Silica

[0104] The heat-insulating silicone composition preferably does not include silica (silicon dioxide).

[0105] Adhesive additives

[0106] The heat-insulating silicone composition preferably does not include adhesive additives.

[0107] Adhesive additives that should preferably not be excluded are organosilicone compounds or siloxanes having an organic functional group in their molecules, or those having a silyl group containing an alkoxy group bonded to a silicon atom. The organic functional group contained in adhesive additives that should preferably not be excluded is an alkoxy group bonded to a silicon atom. Examples of such alkoxy groups bonded to silicon atoms include methoxy groups, ethoxy groups, and propoxy groups. Examples of silyl groups containing an alkoxy group bonded to a silicon atom include alkyldialkoxysilyl groups, such as methyldimethoxysilyl groups, ethyldimethoxysilyl groups, methyldiethoxysilyl groups, and ethyldiethoxysilyl groups. In this case, the silyl group may be bonded to the silicon atom via another group, such as an alkylene group.

[0108] Examples of organic groups that may be included in addition to the groups mentioned above include alkenyl groups, such as vinyl groups, (meth)propenyl groups, hydrogenated silyl groups, isocyanate groups, epoxy groups, alkyl groups, and aryl groups. Preferably, organosilicone compounds or siloxanes do not include those having at least one organic group (e.g., epoxy group, alkyl group, aryl group, etc.) and an alkoxy group with at least two or more silicon atoms bonded.

[0109] When an epoxy group is included as another organic group, the epoxy group may be a straight-chain or branched alkyl group having 1 to 20 carbon atoms or an epoxy group having an aromatic ring, and those containing 2 to 3 epoxy groups in a molecule are mentioned as adhesive aids that should preferably not be excluded. Examples of groups containing epoxy groups include glycidyloxyalkyl groups, such as glycidyloxypropyl groups, and groups bonded to silicon atoms in the form of epoxy-containing cyclohexylalkyl groups, such as 2,3-epoxycyclohexylethyl groups and 3,4-epoxycyclohexylethyl groups.

[0110] Specific examples of adhesive additives that should preferably not be excluded include vinyltrimethoxysilane, tetraethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, oligomers of 3-glycidoxypropyltrimethoxysilane, oligomers of 3-glycidoxypropyltriethoxysilane, methacryloxysilane (such as 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane), 3-trimethoxysilylpropylsuccinic anhydride, and furan diones such as dihydro-3-(3-(triethoxysilyl)propyl)-2,5-furan dione.

[0111] In the heat-insulating silicone composition of the present invention, as an additional optional component in addition to the aforementioned components (A) to (E), generally known additives used in silicone rubbers or gels may be used, provided that the purpose of the present invention is not impaired. Examples of such additives include crosslinking agents, organosilicon compounds or siloxanes (also known as silane coupling agents) that produce silanols by hydrolysis, reaction rate regulators, condensation catalysts, pigments, dyes, curing inhibitors, heat resistance imparting agents, flame retardants, antistatic agents, conductivity imparting agents, airtightness improvers, radiation shielding agents, electromagnetic wave shielding agents, preservatives, stabilizers, organic solvents, plasticizers, fungicides, organopolysiloxanes containing a hydrogen atom or alkenyl group bonded to a silicon atom within one molecule and containing no other functional groups, and nonfunctional organopolysiloxanes containing neither a hydrogen atom bonded to a silicon atom nor an alkenyl group bonded to a silicon atom. These optional components can be used individually or in combination of two or more types as appropriate.

[0112] Component (F): Reaction rate regulator

[0113] The reaction rate regulator is, for example, a regulator capable of regulating the curing rate of an addition reaction, and examples include alkyne compounds, hydrazines, triazoles, phosphines, and thiols. Any curing inhibitor that is generally considered in the art to have a curing inhibition effect can be used as a reaction rate regulator. Examples of such compounds include phosphorus-containing compounds (such as triphenylphosphine), nitrogen-containing compounds (such as tributylamine, tetramethylethylenediamine, and benzotriazole), sulfur-containing compounds, alkyne compounds, compounds containing two or more alkenyl groups, hydroperoxide compounds, maleic acid derivatives, silanes having amino groups, and silicone compounds having amino groups.

[0114] In particular, in this invention, it is preferable to have a small effect on flowability and to cure at room temperature. In this case, examples of reaction rate modifiers include various "enyne" systems, such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne with low viscosity (e.g., 100 mPa·s or less); alkynols, such as 3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclohexanol and 2-phenyl-3-butyn-2-ol; known dialkyl-, dienyl-, and dialkoxyalkyl-fumarates and maleates; and those containing cyclovinylsiloxanes.

[0115] Component (G): Pigment

[0116] Examples of pigments include titanium dioxide, aluminum silicate acid, iron oxide, zinc oxide, calcium carbonate, carbon black, rare earth oxides, chromium oxide, cobalt pigments, ultramarine, cerium silanol, aluminum oxide, aluminum hydroxide, titanium yellow, barium sulfate, precipitated barium sulfate, and mixtures thereof.

[0117] Under normal circumstances, the amount of pigment blended relative to the total mass of the insulating silicone composition is preferably in the range of 0.001% to 5%. However, the effective amount is used depending on the desired curing temperature and curing time for the application. The amount of pigment is preferably in the range of 0.01% or more and 2% or less, and more preferably 0.05% or more and 1% or less. If the amount is less than 0.001%, the resulting composition will not be sufficiently colored, making it difficult to visually distinguish the first liquid from the second liquid. On the other hand, if the amount exceeds 5%, the cost will increase, which is economically undesirable.

[0118] Component (I): Dispersant

[0119] A dispersant may be used for the purpose of highly dispersing component (C) in the system and suppressing reaggregation. The dispersant is preferably an organopolysiloxane having an organic functional group in its molecule, or those having a silyl group containing an alkoxy group bonded to a silicon atom. Examples of organic functional groups include carboxyl groups, amino groups, alkyl groups, hydrogenated silyl groups, isocyanate groups, epoxy groups, aryl groups, polyether groups, polyglucosyl groups, methoxy groups, ethoxy groups, and propoxy groups. More preferred examples of dispersants include organopolysiloxanes having at least one organic group at its end or in its side chain, wherein the organic group is selected from carboxyl groups, amino groups, epoxy groups, polyether groups, and similar groups. Examples of silyl groups containing alkoxy groups bonded to silicon atoms include alkyldialkoxysilyl groups, such as methyldimethoxysilyl groups, ethyldimethoxysilyl groups, methyldiethoxysilyl groups, and ethyldiethoxysilyl groups. In this case, the silyl group may be bonded to the silicon atom via another group, such as an alkylene group. Furthermore, more specific examples of dispersants may include carboxyl-modified organopolysiloxanes, non-reactive amino-modified organopolysiloxanes, and epoxy-modified organopolysiloxanes. As a commercially available carboxyl-modified organopolysiloxane, WACKER M 642 manufactured by Wacker Chemie AG can be used. As a commercially available non-reactive amino-modified organopolysiloxane, WACKER FINISH WT 1270 manufactured by Wacker Chemie AG can be used. As a commercially available epoxy-modified organopolysiloxane, WACKER SILICON FLUID 22254 VP manufactured by Wacker Chemie AG can be used.

[0120] As a dispersant other than organosilicon compounds or organopolysiloxanes, titanate coupling agents having hydrophobic groups such as alkyl groups are also preferred, and for example, triisostearyloxyisopropoxytitanium is preferred.

[0121] Using a dispersant with organic functional groups can help disperse component (C) by the interaction between the organic functional groups and the hydrophilic groups on the surface of component (C), thereby reducing the viscosity of the uncured heat-insulating silicone composition and inhibiting the re-aggregation of component (C) during storage. Therefore, the floating of component (C) can be suppressed and the strength of the floating matter can be reduced, which is beneficial for re-stirring.

[0122] The content of the dispersant may be 0.05 parts by mass or more and 2 parts by mass or less, more preferably 0.08 parts by mass or more and 1.0 parts by mass or less, and more preferably 0.1 parts by mass or more and 0.5 parts by mass or less, relative to the total amount of 100 parts by mass of component (A) and component (B).

[0123] The heat-insulating silicone composition of the present invention may contain one or more of the following groups: octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecylcyclohexasiloxane (D6), tetradecylcycloheptasiloxane (D7) and hexadecylcyclooctasiloxane (D8).

[0124] The total content of (D4), (D5), (D6), (D7), and (D8) may be less than 0.1 parts by mass (i.e., less than 1,000 ppm) relative to the total amount of 100 parts by mass of component (A) and component (B).

[0125] When the total content of (D4) to (D8) contained in the heat-insulating silicone composition falls within the aforementioned range, the flash point of the entire composition can be increased, and the safety during storage can be improved. Furthermore, the cured product obtained by curing the composition can be provided in a manner in which the cured product is unlikely to cause contact failure with electronic components, etc.

[0126] A heat-insulating silicone composition containing less than 0.1 parts by mass of (D4) to (D8) (as the total content of (D4) to (D8)) can be produced by using component (A) (where the total content of (D4) to (D8) xA is less than 0.1 parts by mass) and component (B) (where the total content of (D4) to (D8) xB is less than 0.1 parts by mass, such that the total content xA+xB is less than 0.1 parts by mass) with a total content of less than 0.1 parts by mass of (D4) to (D8).

[0127] The corresponding contents of (D4) to (D8) were measured by gas chromatography. The measurement conditions of gas chromatography can be appropriately selected according to generally known methods.

[0128] Two-component type:

[0129] In an embodiment of the present invention, a two-component separated thermal silicone composition can be used, wherein the first liquid and the second liquid are mixed to begin curing.

[0130] The first liquid contains, for example, components (A), (C), and (D). The first liquid may also contain a reaction rate regulator, a pigment, and a dispersant. Components (A), (C), and (D), the reaction rate regulator, and the pigment in the first liquid may each be of a single type or two or more types.

[0131] The second liquid contains components (A), (B), (C), and (E). Each of the components (A), (B), (C), and (E) in the second liquid may be a single type or two or more types. The second liquid may also contain a dispersant.

[0132] Neither the first liquid nor the second liquid contains silica or adhesive additives.

[0133] First Liquid:

[0134] Relative to 100 parts by mass of their total mixture, the first liquid may contain: 80 or more and 96 or less of component (A), 5 or more and 15 or less of component (C), 0.1 or more and 0.5 or less of component (D), 0.1 or less of reaction rate regulator (F), 0.2 or less of pigment (G), and 0.5 or less of dispersant (I).

[0135] Second Liquid:

[0136] The second liquid may contain, relative to 100 parts by mass of their total mixture, 24 parts by mass or more and 36 parts by mass or less of component (A), 55 parts by mass or more and 65 parts by mass or less of component (B), 8 parts by mass or more and 10 parts by mass or less of component (C), 0 parts by mass or more and 2.5 parts by mass or less of component (E), and 0.5 parts by mass or less of dispersant (I).

[0137] The bipartite thermal silicone composition comprises, relative to 100 parts by mass, a first liquid in an amount of 40 parts by mass or more and 60 parts by mass or less, and a second liquid in an amount of 60 parts by mass or less and 40 parts by mass or more.

[0138] Method for preparing a heat-insulating cured product: The method for preparing a heat-insulating cured product obtained by curing the heat-insulating silicone composition of the present invention includes: a step of mixing a first liquid with a second liquid to prepare a heat-insulating silicone composition; a step of potting the heat-insulating silicone composition onto a substrate (filling and coating step) to form a potting layer; and a step of curing the potting layer at a temperature of 5°C or higher and 100°C or lower, and more preferably 15°C or higher and 50°C or lower, for a predetermined time period.

[0139] The preferred curing temperature is room temperature curing. Rapid curing can be performed at temperatures above room temperature. However, it is preferable to set a curing temperature that will not cause deformation (such as shrinkage) in component (C).

[0140] Curing time depends on curing temperature and can be shortened at higher curing temperatures.

[0141] Substrate:

[0142] Examples of substrates include various substrates used in various electrical and electronic components, automotive components, various computer-related components such as PCs and portable terminals, battery cells, electrical devices and electronic devices.

[0143] Electrical and electronic devices are not particularly limited, and examples include mobile phones, smartphones, tablet computers, smartwatches, computers, semiconductor packaging substrates, electronic circuit boards, LED packaging substrates, sensor substrates, imaging device substrates, liquid crystal substrates and organic EL substrates.

[0144] The heat-insulating silicone composition can be potted and cured in the gaps between multiple substrates.

[0145] The heat-insulating silicone composition can be poured and cured in the gaps between the components of the substrate.

[0146] Example:

[0147] In the following, examples of two-component mixtures will be described. However, the invention is not limited to the following examples. Table 1 shows various conditions for the corresponding components of the first liquid. Table 2 shows various conditions for the corresponding components of the second liquid.

[0148] [Table 1]

[0149] [Table 2]

[0150] Table 3 shows the blending ratio of the corresponding components of the first liquid in each of Examples 1 to 15, and Table 4 shows the blending ratio of the corresponding components of the second liquid. Table 5 shows the blending ratio of the corresponding components when the first and second liquids are mixed in each of Examples 1 to 15. Table 6 shows the evaluation results of Examples 1 to 15. The blending ratio values ​​are indicated in parts by mass. The hollow filler formed from the organic resin is a polymer mainly composed of acrylonitrile, methyl methacrylate, and methacrylonitrile.

[0151] [Table 3]

[0152] [Table 4]

[0153] [Table 5]

[0154] [Table 6] ("nd" indicates no data)

[0155] Comparative Example:

[0156] Table 7 shows the blending ratio of the corresponding components of the first liquid in each of Comparative Examples 1 to 6, and Table 8 shows the blending ratio of the corresponding components of the second liquid. Table 9 shows the blending ratio of the corresponding components when the first liquid and the second liquid are mixed in each of Comparative Examples 1 to 6. Table 10 shows the evaluation results of Comparative Examples 1 to 6. The blending ratio values ​​are indicated in parts by mass.

[0157] [Table 7] Comparative example Components / Functions 1 2 3 4 5 6 First Liquid A-1 Organic polysiloxane 91.12 40.00 40.00 40.00 90.42 A-2 50.42 50.42 45.46 81.62 A-3 5.00 C-1 filler 18.00 C-2 9.20 9.20 9.20 9.20 C-3 C-4 C-5 C-6 C-7 C-8 C-9 8.50 D Addition catalyst 0.24 0.24 0.24 0.24 0.24 0.24 F Reaction rate regulator 0.04 0.04 0.04 0.04 0.04 0.04 G pigment 0.10 0.10 0.10 0.10 0.10 0.10 I-1 dispersant I-2 100.0 100.0 100.0 100.0 100.0 100.0

[0158] [Table 8] Comparative example Components / Functions 1 2 3 4 5 6 Second liquid A-1 Organic polysiloxane 34.48 9.23 12.63 51.00 21.42 A-3 17.07 18.57 45.70 A-4 4.45 B-1 Organohydrogen polysiloxane 48.98 55.22 55.22 37.02 57.00 B-2 1.80 7.50 1.00 1.80 B-3 2.60 B-4 41.00 C-1 filler 18.00 C-2 9.20 9.20 9.20 9.20 C-3 C-4 C-5 C-6 C-7 C-8 C-9 8.50 E-1 Silicone resin 1.79 1.78 1.78 1.78 1.78 E-2 E-3 H-1 Adhesive additive 1.60 H-2 2.50 I-1 dispersant I-2 100.0 100.0 100.0 100.0 100.0 100.0

[0159] [Table 9] Comparative example Components Component Name 1 2 3 4 5 6 Quality A Organopolysiloxanes containing alkenyl groups 72 65 68 77 79 64 B Organohydrogen polysiloxane 28 35 32 twenty three twenty one 36 E-1 silicone resin 0.4 0.4 0.4 0.4 0.5 E-2 E-3 F Reaction rate regulator 0.02 0.02 0.02 0.05 0.02 0.02 D Addition reaction catalyst 0.13 0.13 0.13 0.09 0.13 0.15 G pigment 0.05 0.06 0.06 0.06 0.06 0.06 H Adhesive additives 2.3 I dispersant C-1 filler 27 C-2 10 10 10 10 C-3 C-4 C-5 C-6 C-7 C-8 C-9 9 Theoretical weight 0.66 0.66 0.66 0.66 0.66 0.66 SiH / Alkenyl Group 0.75 1.10 1.25 2.00 0.49 0.80

[0160] [Table 10] Comparative example Acceptance Standards 1 2 3 4 5 6 thermal conductivity Thermal conductivity analyzer <= 0.20 [W / mK] 0.15 0.13 0.13 0.13 0.13 0.14 hardness Penetration 10 to 40 [1 / 10 mm] 32 4 3 2 96 19 density underwater < 0.7 [g / cc] 0.69 0.65 0.65 0.65 0.64 0.67 Difference from theoretical proportion < 3 [%] 3.8% -0.9% -0.9% -1.7% -2.7% 1.0% viscosity First Liquid (D = 10) 1000 to 4000 [mPa.s] 1,570 1,416 1,416 1,340 1,900 8,840 Second liquid (D = 10) 1000 to 4000 [mPa.s] 1,180 1,351 1,251 1,680 713 1,980 Mixture (D = 10) 1000 to 4000 [mPa.s] 1,480 1,415 1,315 1,340 1,160 4,970 stretching strength >50 [kPa] 44 258 320 487 nd nd Displacement > 275 [%] 195 194 125 34 nd nd Float Liquid phase height: First liquid [mm] 24.5 nd nd nd 17.0 nd Difference from theoretical value of liquid phase height: First liquid < 65% 71% nd nd nd 50% nd Liquid phase height: Second liquid [mm] 29.3 nd nd nd 23.0 nd Difference from theoretical value of liquid phase height: Second liquid < 65% 85% nd nd nd 68% nd Strength of floating objects Test force: First liquid < 2 [N] 15.3 nd nd nd 0.1 nd Test force: Second liquid < 2 [N] 18.6 nd nd nd 1.5 nd Volume change rate 200°C / 2 hours < 0 [%] 1.00 nd nd 0.00 nd nd

[0161] Preparation method:

[0162] The heat-insulating silicone composition is produced by mixing the first liquid and the second liquid shown in each of the examples and comparative examples.

[0163] For example, 40% by weight equivalent of the liquid material in the composition (first liquid or second liquid) and the total amount of the packing are placed in a planetary centrifugal mixer and mixed for 2 minutes at a rotational speed of 660 rpm and a rotational speed of 220 rpm. Then, the remaining liquid material (60% by weight) is fed into it and mixed for 2 minutes at the same speed as above.

[0164] Subsequently, the first liquid and the second liquid are mixed at a mass ratio of 1:1.

[0165] Subsequently, various evaluations were performed on the mixture before curing (uncured state) and after curing. The evaluation methods (measurement methods) for each evaluation will be described below.

[0166] Theoretical proportion:

[0167] The theoretical specific gravity is calculated from the specific gravity of each component and their blending ratio.

[0168] Mollbi:

[0169] [Si-H group / alkenyl group] The molar ratio is the ratio of the total amount of Si-H groups contained in the entire insulating silicone composition to the total amount of alkenyl groups bonded to silicon atoms in component (A).

[0170] Thermal conductivity:

[0171] The thermal conductivity of the heat-insulating cured product at 25°C was measured according to ISO 22007-2. The heat-insulating silicone composition was cured at 100°C for 30 minutes to produce test specimens with a diameter of 40 mm and a height of 10 mm. The sensor was then clamped between the two resulting test specimens to measure the thermal conductivity (W / mK) using a TPS-500 measuring instrument (manufactured by Hot Disk).

[0172] Needle penetration:

[0173] The penetration of the heat-insulating cured product at 23°C was measured according to ASTM D 2240. The penetration of the heat-insulating cured product obtained by curing the heat-insulating silicone composition at 100°C for 30 minutes was measured in a 60 ml container using an automated penetration / consistency measuring instrument (PENETROMETER RPM-101). "Penetration" is indicated by the length of the portion of the sample penetrated by a standard steel needle at a constant temperature. The penetration length was measured while holding a 100 g load for 5 seconds, and the obtained penetration depth was expressed in increments of 1 / 10 mm.

[0174] Density:

[0175] The density of the heat-insulating cured product at 23°C was measured according to JIS K 6249. The density (g / mL) of the test specimen obtained by curing the heat-insulating silicone composition at 100°C for 30 minutes was measured by underwater displacement method using a densitometer (AUTOMATIC DENSIMETER, model DSG-1).

[0176] Calculate the difference (%) between the theoretical and actual weights.

[0177] Viscosity:

[0178] The viscosity of the insulating silicone composition at 25°C was measured according to JIS K 7117-2. The uncured insulating silicone composition was placed between a cone with a diameter of 25 mm and rotated at an angle of 1° or 2° and a fixed plate, and the viscosity was measured using a Physica MR 301 viscometer (manufactured by Anton Paar) at a shear rate of 10 (1 / s) and a gap of 0.106 mm.

[0179] In Table 6, "First liquid (D=10)" indicates the viscosity of the first liquid at a shear rate of 10 (1 / s), "Second liquid (D=10)" indicates the viscosity of the second liquid at a shear rate of 10 (1 / s), and "Mixture (D=10)" indicates the viscosity of the mixture of the first liquid and the second liquid at a shear rate of 10 (1 / s).

[0180] Tensile strength:

[0181] The tensile strength of the heat-insulating cured product at 25°C was measured according to JIS K 6251. A 2 mm thick sheet obtained by curing the heat-insulating silicone composition at 100°C for 30 minutes was stamped into a No. 3 dumbbell shape, and the breaking strength (kPa) and elongation (displacement %) were measured using a tensile testing machine (Autograph AGS-X, manufactured by Shimadzu Corporation) at a tensile speed of 500 mm / min.

[0182] Floating property:

[0183] 40% by weight equivalent of the liquid material in the first or second liquid and the total amount of packing were placed in a planetary centrifugal mixer and mixed for 2 minutes at a rotational speed of 660 rpm and a rotational speed of 220 rpm. Then, the remaining liquid material (60% by weight) was fed into the mixer and mixed for 2 minutes at the same speed as above.

[0184] Subsequently, the buoyancy of the filler was determined by the interfacial position between the liquid phase (silicone phase) and the filler phase (component (C) phase) after the uncured insulating silicone composition had been left to stand for a specific period of time. The material (first liquid or second liquid) was poured into a 50 mL container with a diameter of 35 mm and a height of 78 mm to a filling height of 55 mm from the bottom, and stored under high temperature conditions for a specified period of time (e.g., one week at 50°C). The interfacial position between the silicone phase and the filler phase was then measured using tools such as a ruler. The buoyancy of the filler component was determined by the interfacial position and the filling amount of the filler component.

[0185] Calculate the volume fraction of component (C) in the thermal insulation silicone composition (first liquid or second liquid) relative to the blending amount of other components.

[0186] Theoretical height of the liquid phase H0 = volume fraction of the liquid phase (e.g., 6 / 10) × filling height (=55 mm)

[0187] Measure the height H1 of the liquid phase after storing it at high temperature for a specified period of time using a ruler.

[0188] Floating property (%) = H1 / H0 × 100

[0189] In Table 6, "Liquid phase height: first liquid" and "Difference from theoretical value of liquid phase height: first liquid" indicate the evaluation results of the first liquid, and "Liquid phase height: second liquid" and "Difference from theoretical value of liquid phase height: second liquid" indicate the evaluation results of the second liquid.

[0190] Strength of floating objects:

[0191] The strength of the filler component (component (C)) floating on the sample surface after the buoyancy evaluation test was measured. The maximum load value (N) was measured using a compression testing machine (Autograph AGS-X, manufactured by Shimadzu Corporation) when a spherical compression clamp with a diameter of 12.7 mm was pressed onto the sample at a compression rate of 240 mm / min to penetrate the sample.

[0192] In Table 6, "Test Force: First Liquid" indicates the strength result in the first liquid, and "Test Force: Second Liquid" indicates the strength result in the second liquid.

[0193] Volume change rate:

[0194] The weight and density of a test specimen with a diameter of 40 mm and a height of 10 mm, obtained by curing the heat-insulating silicone composition at 100°C for 30 minutes, were measured to calculate the volume (before heat shrinkage). The weight and density of the test specimen after heating in an oven at 200°C for 2 hours and then cooling to room temperature were measured to calculate the volume (after heat shrinkage). The volume change rate (%) was calculated from the difference between the volume before heating and the volume after heating.

[0195] Volume change rate (%) = {(Volume after heat shrinkage) – (Volume before heat shrinkage)} / (Volume before heat shrinkage) × 100

[0196] Evaluation of the embodiment:

[0197] In Example 1, in which the polymer viscosity and molar ratio (Si-H group / olefin group) were adjusted, the hardness, viscosity, buoyancy and buoyancy strength were better than those in the comparative examples, and the volume change rate (shrinkage characteristics) was also greater.

[0198] In Example 2, where the amount of component (A) is increased instead of the silicone resin (component (E)) of Example 1, tensile strength and displacement are improved.

[0199] In Example 3, in which a different silicone resin than that used in Example 1 was used, tensile strength and displacement were improved.

[0200] In Example 4, in which a different silicone resin than that used in Example 1 was used, the tensile displacement was improved.

[0201] In Example 5, in which the amounts of components (B) and (C) are increased compared to those in Example 1 and the amount of component (A) is decreased compared to those in Example 1, the viscosity increases.

[0202] In Example 6, where the filler in Examples 1 to 5 is replaced by a filler (component (C)) having a comparable particle size and a comparable specific gravity but having undergone a treatment that imparts surface hydrophobicity (fatty acid treatment), the viscosity is reduced and thus the filler becomes possible to float.

[0203] In Example 7, in which the amount of component (B) and component (C) of Example 1 is increased and the amount of component (A) of Example 1 is decreased, the viscosity increases.

[0204] In Example 8, in which the filler of Examples 1 to 5 was replaced with a different filler (talc surface treatment), the thermal conductivity increased and the viscosity decreased.

[0205] In Example 9, in which the filler of Examples 1 to 5 was replaced by a resin filler having a larger particle size and a large amount of attached inorganic material, the thermal conductivity increased and the viscosity decreased.

[0206] In Example 10, where the filler of Example 1 was replaced with a resin filler having a smaller particle size and the same specific gravity, the tensile displacement was improved.

[0207] In Example 11, where the filler of Example 1 was replaced with a resin filler having a comparable particle size and lower specific gravity, the viscosity was reduced, and thus the filler became possible to float.

[0208] In Example 12, where the filler of Example 1 was replaced with a resin filler having a comparable particle size and a lower specific gravity, the viscosity was reduced.

[0209] In Example 13, where the amount of component (A) is increased instead of the silicone resin (component (E)) of Example 11, the strength of the float is reduced.

[0210] Except for the addition of carboxyl-modified silicone oil, Example 14 is the same as Example 13. Due to this addition, the viscosity is reduced, and the strength of the floating matter is reduced.

[0211] Except for the addition of non-reactive modified silicone oil, Example 15 is the same as Example 13. Due to this addition, the viscosity is reduced and the strength of the floating matter is reduced.

[0212] Evaluation of the comparative examples:

[0213] In Comparative Example 1, the difference from the theoretical specific gravity was as high as 3% or more. Tensile strength and displacement were low, and softness was also low. The strength of the floating matter after storage was high, and re-stirring was difficult.

[0214] In Comparative Example 2, in which the molar ratio (Si-H group / alkenyl group) was increased compared to Example 1, the penetration was lower.

[0215] In Comparative Example 3, in which the molar ratio (Si-H group / alkenyl group) was increased compared to Example 1, the penetration was lower.

[0216] In Comparative Example 4, in which component (B) of Example 1 was changed to an organohydrogen polysiloxane containing more than 0.005 moles / gram of hydrogen atoms bonded to silicon atoms and the mole ratio (Si-H group / alkenyl group) of hydrogen atoms bonded to silicon atoms to alkenyl groups bonded to silicon atoms was changed to 2 or more and an adhesive aid was added to the composition of Example 1, the hardness increased and the elongation decreased.

[0217] In Comparative Example 5, in which the molar ratio (Si-H group / alkenyl group) of Example 1 was reduced, the penetration was higher.

[0218] In Comparative Example 6, in which the filler of Example 1 was changed to a resin filler with high specific gravity and small particle size, the hardness and viscosity increased.

Claims

1. A heat-insulating silicone composition comprising: component (A), which is an organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms within one molecule; component (B), which is an organohydrogen polysiloxane containing 0.0001 mol / g or more and 0.005 mol / g or less of hydrogen atoms bonded to silicon atoms; component (C), which is a hollow filler formed from an organic resin; and component (D), which is an addition reaction catalyst, wherein: The content of component (C) is 5 parts by mass or more and 25 parts by mass or less relative to the total amount of 100 parts by mass of component (A) and component (B), the content of component (D) is 0.05 parts by mass or more and 1.8 parts by mass or less, and the molar ratio of the total amount of Si-H groups contained in the entire insulating silicone composition to the total amount of alkenyl groups bonded to silicon atoms in component (A) [Si-H groups / alkenyl groups] is 0.5 or more and 1.0 or less.

2. The heat-insulating silicone composition as claimed in claim 1, wherein: The component (C) has a true density of 0.2 g / cm³ or less, and / or the component (C) has an average particle size of 150 μm or less.

3. The insulating silicone composition as claimed in claim 1, having a viscosity of 10,000 mPa·s or less at 25°C as measured according to JIS K 7177-2.

4. The heat-insulating silicone composition as claimed in claim 1, wherein the heat-insulating cured product obtained by curing the heat-insulating silicone composition has a hardness in terms of needle penetration of 10 or more and 40 or less.

5. The insulating silicone composition as claimed in claim 1, wherein, when heated at 190°C to 210°C for 1 to 2.5 hours, the volume shrinkage of the insulating cured product obtained by curing the insulating silicone composition after heating is 15% or more and 34% or less, compared to before heating.

6. A method for preparing a heat-insulating cured product obtained by curing a heat-insulating silicone composition as described in any one of claims 1 to 5, comprising: The step of encapsulating the heat-insulating silicone composition onto a substrate to form an encapsulation layer; The step of curing the potting layer at a temperature of 5°C or higher and 100°C or lower.