A curable polysiloxane composition with high thermal insulation performance at high temperatures.

Abstract

A curable polysiloxane composition is provided, comprising: (A) 100 parts by weight of at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule; (B) 0.5 to 20 parts by weight of at least one organopolysiloxane having at least two hydrogen atoms bonded to silicon per molecule; (C) a catalytic amount of a hydrosilylation catalyst; (D) 2 to 150 parts by weight of at least one flame-retardant filler; and (E) water, wherein component (E) water is dispersed as water droplets in a mixture of components (A), (B), (C), and (D), and the average droplet size is 100 μm or less. The curable polysiloxane composition exhibits significantly improved thermal insulation performance at high temperatures. A process for producing a polysiloxane composite from a curable polysiloxane composition, the use of the polysiloxane composite as a thermal insulation material, and an article containing the polysiloxane composite obtained from the curable polysiloxane composition for thermal insulation.

Description

[Technical Field]

[0001] The present invention relates to a curable polysiloxane composition having high thermal insulation performance at high temperatures. The present invention also relates to a process for producing a polysiloxane composite from a curable polysiloxane composition, and to an article comprising a polysiloxane composite obtained from a thermal insulation curable polysiloxane composition. [Background technology]

[0002] Polysiloxane foam exhibits superior performance compared to other organic polymer foams due to its stability over a wide range of operating temperatures. In particular, when the application temperature exceeds the temperature that induces Si-O-Si bond dissociation (above 350°C), silicone foam ceramicizes into an inorganic porous material, continuing to occupy its original space and thus providing a certain level of fire and thermal protection. At such high temperatures, other polymer foams, such as polyurethane, polypropylene, and polystyrene foams, decompose and can no longer provide any significant protection. The combination of high cushioning and flexibility at working temperatures (<250°C) and fire and thermal protection at higher temperatures (>350°C) makes silicone foam unique and indispensable.

[0003] Meanwhile, the demand for improved thermal insulation performance at high temperatures is increasing. The petroleum industry and energy storage applications require thermal insulation performance exceeding that of inorganic materials. One important challenge is how to reduce the cell size of silicone foam, because cell size is crucial for thermal insulation properties. In conventional technology, chemically foamed liquid silicone rubber (LSR) typically uses hydrogen gas for foaming, which is usually produced by reacting OH groups (usually in alcohol) with Si-H groups in polydimethylsiloxane (PDMS). For example, Patent Document 1 discloses a thermally insulating fireproof sheet having an elastomer layer. The elastomer layer is a cured silicone foam rubber containing alumina trihydrate. This layer is foamed by H2 generated from a foam layer containing a silicone matrix component, a flame-retardant filler component, and an insulating filler component. Patent Document 2 also discloses a composite material for producing closed-cell silicone foam. The claimed composite material comprises two parts. Part A contains 100 parts polysiloxane-containing vinyl, 2 to 8 parts hydrogen-containing silicone oil, 20 to 80 parts flame-retardant filler, and 2 to 10 parts reinforcing filler. Part B contains 114 parts polysiloxane-containing vinyl, 20 to 80 parts flame-retardant filler, 2 to 6 parts reinforcing filler, 0.2 to 1.2 parts catalyst, and 20 to 50 parts blowing agent. The blowing agent is an alcohol-type chemical that can react with Si-H groups to produce H2. In such a process, larger bubble sizes can be obtained with higher porosity and slower curing speed. Depending on the final porosity and the relationship between curing speed and blowing speed, the bubble size varies from 100 μm to several millimeters, but it is not possible to achieve smaller bubble sizes than 100 μm. Such large-sized silicone foams exhibit only insufficient thermal insulation.

[0004] When using high-consistency silicone rubber (HCR) as a foam matrix, a bubble size of 100 μm or less can be achieved by adding azo-type foaming agent powder. The foaming agent decomposes, generating nitrogen gas for foaming. However, there are safety concerns regarding the decomposition residue of the foaming agent, and its odor is irritating, limiting its application. Finding an environmentally friendly process to further enhance thermal insulation properties remains a major challenge for silicone foams, especially for applications at high temperatures.

[0005] There are known approaches, as documented in prior art, for preparing silicone foam using environmentally friendly processes. An exemplary approach, as disclosed in Patent Document 3, is a silicone foam prepared by a water-in-oil (W / O) emulsion. The emulsion composite contains alkenyl group-containing organopolysiloxane (I) (parts by weight) (100), surfactant (1-300), hydrogenated organopolysiloxane (II) (0.1-50), water (20-1500), and a platinum group catalyst. When this composite is heated, components (I) and (II) further react to form a wet foam, and when water is removed, bubbles remain in the cured silicone matrix. That is, in this approach, water is dispersed as droplets in the silicone matrix, and when heated, these water droplets are removed, leaving numerous small pores (bubbles) in the silicone matrix to form the silicone foam. Therefore, in this approach, water is used to form droplets in the silicone matrix instead of participating in chemical reactions to generate bubbles.

[0006] However, this process still has several problems. Because silicone oil is highly hydrophobic, a large amount of surfactant is required to emulsify water in the silicone oil to obtain a stable emulsion containing fine droplets and having a narrow droplet size distribution, as disclosed in Patent Document 3. Some surfactants can poison the platinum catalyst, and therefore the ceramicization efficiency decreases at temperatures above 350°C. For this reason, such a process has not been applied to high-temperature silicone composites in high-temperature ceramicization. [Prior art documents] [Patent Documents]

[0007] Patent Document 1: U.S. Patent Publication No. 4822659(A) Patent Document 2: Chinese Patent Publication No. 110591378(A) Patent Document 3: Japanese Unexamined Patent Publication No. 2004091569(A) [Overview of the project] [Problems that the invention aims to solve]

[0008] In the field of silicone foam technology, silicone foams with significantly improved thermal insulation performance are not well known. There are only a few prior art materials for silicone rubber (e.g., Patent Documents 1, 2, and 3), but all of them exhibit several problems, such as reduced thermal insulation properties due to larger cell sizes and / or lower closed-cell ratios, pungent odors due to the chemical foaming process, and degradation of ceramicization at high temperatures.

[0009] Therefore, an object of the present invention is to provide a curable polysiloxane composition with significantly improved thermal insulation performance at high temperatures. In particular, an object of the present invention is to provide a curable polysiloxane composition that can form a polysiloxane composite material having a higher closed-cell ratio and a reduced cell size of 100 μm or less by an emulsion process.

[0010] Furthermore, another object of the present invention is to provide a process for producing a polysiloxane composite from a curable polysiloxane composition, the use of the polysiloxane composite as a thermal insulation material, and an article comprising the polysiloxane composite obtained from the curable polysiloxane composition for thermal insulation. [Means for solving the problem]

[0011] As a result of diligent research, the inventors have discovered a novel composite material that significantly reduces the thermal conductivity of the resulting polysiloxane composite material at a temperature high enough to induce the dissociation of Si-O-Si bonds. This invention is the result of this discovery.

[0012] One aspect of the present invention is a curable polysiloxane composition, (A) 100 parts by weight of at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, (B) 0.2 to 20 parts by weight of at least one organopolysiloxane having at least two hydrogen atoms bonded to silicon per molecule, (C) A catalytic amount of hydrosilylation catalyst, (D) At least one flame-retardant filler in an amount of 2 to 250 parts by weight, (E) Water and, This is a curable polysiloxane composition comprising, in which component (E) water is dispersed as water droplets in a mixture of components (A), (B), (C), and (D), with an average droplet size of 100 μm or less.

[0013] In some embodiments, the curable polysiloxane composition contains (F) at least one thickener, and when component (F) the thickener is added to component (E) water, the resulting thickened water (M) is 0.1 s -1 50,000-400,000 cst, 10s -1 It further contains an amount having a viscosity in the range of 5,000 to 10,000 cst.

[0014] In some embodiments, the curable polysiloxane composition further comprises (G) at least one emulsifier in an amount sufficient to promote the dispersion of component (E), water or thickened water (M), into water droplets having an average droplet size of 100 μm or less.

[0015] In some embodiments, the curable polysiloxane composition further comprises (H) at least one hydrosilylation catalyst inhibitor in an amount sufficient to inhibit the hydrosilylation catalyst at a relatively low temperature.

[0016] In some embodiments, the curable polysiloxane composition further comprises (I) at least one opacifying agent.

[0017] In some embodiments, component (E), water, is included in an amount of 5 to 1,000 parts by weight based on 100 parts by weight of the total amount of components (A), (B), (C), (D), (H), and (I).

[0018] In some embodiments, the organopolysiloxane (A) preferably has the formula:

[0019]

Chemical formula

[0020] In some embodiments, the organopolysiloxane (B) preferably contains a copolymer of trimethylsiloxy and methylhydrogensilicon, or a copolymer of trimethylsiloxy, methylhydrogensilicon, and dimethylsilicon.

[0021] In some embodiments, the hydrosilylation catalyst (C) is preferably selected from the group consisting of platinum, palladium, rhodium, nickel, iridium, ruthenium catalysts, and mixtures thereof, but is not limited thereto.

[0022] In some embodiments, the flame-retardant filler (D) is preferably selected from the group consisting of aluminum hydroxide, magnesium hydroxide, hydromagnesite, ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, and mixtures thereof, but is not limited thereto.

[0023] In some embodiments, the thickener (F) is preferably selected from the group consisting of nanoclay, cellulose, polyacrylate, and mixtures thereof, but is not limited thereto.

[0024] In some embodiments, the emulsifier (G) is preferably selected from the group consisting of polysiloxane polyethers, alkyl-poly(ethylene oxides), and mixtures thereof, but is not limited thereto.

[0025] In some embodiments, the opacifying agent (I) is preferably selected from the group consisting of carbon black, Fe3O4, and mixtures thereof, but is not limited thereto.

[0026] A second aspect of the present invention is a process for producing a polysiloxane composite from the curable polysiloxane composition described in the first aspect, comprising the following steps, namely: Step (I): A mixing step in which component (A) is mixed with other components (B), (C), (D), and optional components (H) and (I) to form a silicone oil composite mixture (N), then component (E) water is added, and the water is dispersed into droplets in the silicone oil composite mixture (N) by sufficient shearing and time, thereby producing a water-in-oil emulsion. Step (II): A heating step in which the water-in-oil emulsion prepared in Step (I) above is heated at a specific temperature and time sufficient to cure the silicone oil composite mixture (N) into a silicone matrix by the reaction of alkylene groups in component (A) and Si-H groups in component (B), thereby producing a cured wet composite in which water droplets are dispersed. Step (III): A drying step in which water is removed from the cured wet composite material prepared in Step (II) by raising the heating temperature to a level higher than the boiling point of water under the operating conditions and removing water from the cured wet composite material over a sufficient period of time, thereby obtaining a dry polysiloxane composite material. It is a process that includes [this].

[0027] In some embodiments, a thickened water (M) is prepared in advance by adding a thickening agent (F) to water (E) before step (I), and then, in step (I), the thickened water (M) is added to the silicone oil composite mixture (N) instead of water (E) to produce a water-in-oil emulsion.

[0028] In some embodiments, the dried polysiloxane composite obtained in step (III) has an average cell size of 100 μm or less.

[0029] A third aspect of the present invention is the use of the polysiloxane composite material obtained in the second aspect as a thermal insulation material.

[0030] A fourth aspect of the present invention is an article comprising a polysiloxane composite material obtained in the second aspect.

[0031] Effects of the invention The present invention provides a curable polysiloxane composition that significantly improves thermal insulation performance at high temperatures, and can form a polysiloxane composite material having a higher closed-cell ratio and a reduced cell size of 100 μm or less through emulsification, curing, and drying processes. It also provides a process for producing a polysiloxane composite material from the curable polysiloxane composition, the use of the polysiloxane composite material as a thermal insulation material, and articles containing the polysiloxane composite material obtained from the thermal insulation curable polysiloxane composition.

[0032] Furthermore, this invention reveals a groundbreaking technology for silicone composites in thermal insulation applications. The realization of silicone composites with superior thermal insulation performance opens up new product areas for silicone rubber manufacturers to meet the need for high thermal insulation performance in various applications such as battery fire protection. [Brief explanation of the drawing]

[0033] [Figure 1] This diagram shows a comparative cut bar technique for testing the thermal conductivity of polysiloxane composites according to this disclosure. [Figure 2] This is an SEM image of Comparative Example 1 according to the present invention. [Figure 3] This is an SEM image of Comparative Example 2 according to the present invention. [Figure 4] This is an SEM image of Example 1 according to the present invention. [Figure 5] This is an SEM image of Example 2 according to the present invention. [Figure 6] This is an SEM image of Example 3 according to the present invention. [Figure 7] This is an SEM image of Example 4 according to the present invention. [Modes for carrying out the invention]

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art in which the invention pertains. Where disclosed herein, “and / or” means “and, or alternatively” or “in addition, or alternatively.” All scopes include endpoints unless otherwise indicated.

[0035] As used herein, the term “thickness” refers to the average of at least three measurements of a dry sheet (e.g., a sheet having a thickness of 0.2 to 10.0 mm) measured using an Ames Gage, Model 13C-B2600 (Ames Corporation Waltham Mass).

[0036] As used herein, the terms “polymer” or “macromolecule” selectively refer to polymers made from one or more different monomers, such as copolymers, terpolymers, tetrapolymers, pentapolymers, etc., and may be random, block, graft, continuous, or gradient polymers.

[0037] In this invention, the singular articles “a,” “an,” and “the” include plural references unless otherwise indicated. In this invention, the terms “comprise,” “comprising,” “contain,” “containing,” “include,” and “including,” and their variations, are the language of non-restrictive claims, i.e., allow for additional elements.

[0038] The present invention provides a curable polysiloxane composition with significantly improved thermal insulation performance at high temperatures. Here, the term "high temperature" has the same meaning as generally understood by those skilled in the art, and in particular, in the present invention, it preferably means a temperature high enough to induce the dissociation of Si-O-Si bonds.

[0039] Specifically, the curable polysiloxane composition of the present invention comprises, essentially consists of, or consists of, (A) 100 parts by weight of at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, (B) 0.5 to 20 parts by weight of at least one organopolysiloxane having at least two hydrogen atoms bonded to silicon per molecule, (C) a catalytic amount of a hydrosilylation catalyst, (D) 2 to 150 parts by weight of at least one flame-retardant filler, and (E) 5 to 1,000 parts of water, wherein component (E) water is dispersed as water droplets in a mixture of components (A), (B), (C), and (D), and the average droplet size is 100 μm or less.

[0040] In some preferred embodiments, the curable polysiloxane composition of the present invention optionally comprises (F) at least one thickening agent, (G) at least one emulsifier, (H) at least one hydrosilylation catalyst inhibitor, and / or (I) at least one opacifying agent.

[0041] Ingredient (A) In the present invention, component (A) is well known in the art, and an example thereof is formula:

[0042] [ka] (In the formula, R 3 and R 4 R is selected from the group consisting of alkyl groups, phenyl groups, and alkenyl groups, each having 1 to 6 carbon atoms per group. 4 The material contains an alkenyl-terminated blocked polyorganosiloxane (i.e., vinyl-terminated PDMS) in which at least 50% are methyl groups. Preferably, the viscosity of component (A) is 100 cst to 200,000 cst, 1,000 cst to 100,000 cst, 5,000 cst to 50,000 cst, 8,000 cst to 16,000 cst, 8,000 cst to 14,000 cst, 8,000 cst to 12,000 cst, or 8,000 cst to 10,000 cst at 25°C.

[0043] In some embodiments of the present disclosure, the alkenyl group contained in component (A) may contain 2 to 14 carbon atoms, 4 to 12 carbon atoms, or 6 to 10 carbon atoms, preferably the alkenyl group is selected from the group consisting of vinyl, allyl, hexenyl, decenyl, and tetradecenyl, most preferably the alkenyl group is a vinyl group.

[0044] In this disclosure, the amount of component (A) is defined as 100 parts by weight, and unless otherwise specified, the amounts of all other components are based on 100 parts by weight of component (A).

[0045] Ingredient (B) In the present invention, component (B) may be used to adjust the crosslinking density and may be any silicone having at least two silicon-bonded hydrogen atoms on average per molecule. The remaining valences of the silicon atoms are filled with divalent oxygen atoms or monovalent alkyl radicals having 1 to 6 carbon atoms per radical, such as methyl, ethyl, propyl, isopropyl, butyl, and hexyl groups, and phenyl groups. The organohydrogen silicone may be a homopolymer, copolymer, or mixture thereof. Preferably, the organohydrogen silicone includes, but is not limited to, a copolymer of trimethylsiloxy and methylhydrogen silicone, or a copolymer of trimethylsiloxy, methylhydrogen silicone, and dimethyl silicone. In embodiments of the present invention, the organohydrogen silicone has at least three silicon-bonded hydrogen atoms on average per molecule. In embodiments of the present invention, the viscosity of component (B) is 1 cst to 500 cst, 2 cst to 300 cst, 5 cst to 100 cst, 10 cst to 80 cst, 10 cst to 60 cst, 10 cst to 40 cst, or 10 cst to 20 cst at 25°C. In one embodiment of the present invention, component (B) contains 0.01 to 1.67% by weight, 0.02 to 1.5% by weight, 0.05 to 1.3% by weight, 0.1 to 1.1% by weight, 0.2 to 1.0% by weight, 0.4 to 0.8% by weight, or 0.5 to 0.6% by weight of SiH. In embodiments of the present invention, component (B) is a hydrogenated silicone oil having a viscosity of 20 cst at 25°C and about 1.6% by weight of SiH.

[0046] Particularly preferably, component (B) may have an amount of 0.2 to 20 parts by weight, 0.5 to 18 parts by weight, 1 to 16 parts by weight, 2 to 14 parts by weight, 5 to 10 parts by weight, or 7 to 9 parts by weight, based on 100 parts by weight of component (A).

[0047] Ingredients (C) In the present invention, component (C) can be selected from the group consisting of platinum, palladium, rhodium, nickel, iridium, ruthenium catalysts, and mixtures thereof, and is preferably a platinum catalyst, which can efficiently promote the reaction of the -SiH group with the vinyl group. Particularly preferred is a two-component curable silicone composition in which the catalyst is an organic platinum compound. Particularly preferred is a two-component curable silicone composition in which the catalyst is a functional organic platinum compound selected from (η-diolefin)(α-aryl)platinum complex, (η-diolefin)(γ-aryl)platinum complex, (η-diolefin)(γ-alkyl)platinum complex, and mixtures thereof. In the present invention, commercially available products can be used.

[0048] In the present invention, component (C) is used in a catalytic amount, i.e., an amount sufficient to catalyze the hydrosilylation reaction between components (A) and (B). Particularly preferably, component (C) may be present in amounts of 0.1 to 2 parts by weight, 0.5 to 1.5 parts by weight, 0.8 to 1.3 parts by weight, or 0.9 to 1.1 parts by weight, based on 100 parts by weight of component (A).

[0049] Ingredients (D) In the present invention, component (D) can further improve flame retardancy. Generally, based on 100 parts by weight of component (A), flame retardant fillers exist in amounts of 2-250% by weight, 5-200% by weight, 10-150% by weight, 15-120% by weight, 15-100% by weight, 20-80% by weight, or 30-50% by weight, depending on the flame retardancy requirements of the polysiloxane composite. If the amount of component (D) is too low, the thermal insulation performance may be insufficient. If the amount of component (D) is too high, the processability may deteriorate or the mechanical performance may decrease.

[0050] The flame retardant filler may include, but is not limited to, those commonly used in silicone foam, aluminum hydroxide, magnesium hydroxide, hydromagnesite, ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, and mixtures thereof.

[0051] Ingredients (E) In the present invention, component (E) is introduced into a silicone matrix under conditions of mixing, or preferably mixing and shearing, mixing and stirring, or a combination of mixing, shearing, and stirring, to give a water-in-oil emulsion, wherein the droplets have an average droplet size of 100 μm or less, 80 μm or less, 50 μm or less, 30 μm or less, 10 μm or less, or 5 μm or less. Preferably, the average droplet size is 100 nm, 300 nm, 500 nm, 800 nm, or 1 μm or more.

[0052] According to the present invention, mixing, shearing, and / or stirring may be carried out by any conventional means or simple mixing for forming mortar. For example, component (E) may be mixed by hand or using a low-shear mixer, e.g., a cement mixer, a static mixer, or a medium or high-shear mixer, e.g., a homogenizer, or other conventional foam mixing device.

[0053] Unlike the conventional art in which water is used as a chemical blowing agent in relatively small amounts, for example, 0.1% to 5% by weight based on the total amount of the curable silicone composition, component (E) in the present invention is present in a much larger amount based on the total amount of the silicone matrix. In some embodiments of the present invention, the amount of component (E) is 5 to 1000 parts by weight, 10 to 800 parts by weight, 10 to 500 parts by weight, 10 to 300 parts by weight, 10 to 150 parts by weight, 20 to 130 parts by weight, 30 to 110 parts by weight, 40 to 100 parts by weight, 50 to 90 parts by weight, or 60 to 70 parts by weight, based on 100 parts by weight of component (A).

[0054] Ingredients (F) To promote the dispersion of water droplets with a relatively small average bubble size and to apply a much larger amount of component (E) into the curable polysiloxane composition, thereby maintaining the viscosity and homogeneity of the water-in-oil emulsion, one or more thickeners may be included. The thickeners are components that thicken the water of the present invention to improve viscosity, homogeneity, workability, and storage stability. The thickeners according to the present invention comprise one or more types selected from water-soluble organic polymers, clay minerals, or mixtures thereof.

[0055] Examples of water-soluble organic polymers include high molecular weight polysaccharides and water-soluble acrylic resins. Specifically, the use of water-soluble organic polymers containing carboxylate groups is preferred, and preferred examples include polyacrylates, which are carboxyl-containing bonded polymers such as sodium polyacrylate and sodium polymethacrylate.

[0056] The clay mineral may be natural or synthetic, and examples include natural or synthetic smectite clays such as bentonite, montmorillonite, hectorite, saponite, souconite, bydelite, and nontronite, with magnesium aluminum silicate being an example. Smectite clays such as bentonite and montmorillonite are preferred. Such smectite clays are available, for example, as SUMECTON SA (manufactured by Kunimine Industries Co., Ltd.), a hydrothermally synthesized product, and BEN-GEL (manufactured by HOJUN., Co., Ltd.), a naturally refined product. These clay minerals may be synthetic smectite clays, and it should be noted that synthetic smectite clays generally have smaller particle sizes than natural smectite clays. For example, the average particle size is only 5 or 10% of the average particle size of natural smectite. Because synthetic smectite clays have such small particle sizes, they can be added in smaller amounts than natural smectite clays to produce highly viscous aqueous gel compositions. The pH of these clay minerals, such as smectite clay, is preferably in the pH range of 5.0 to 9.0.

[0057] Water-soluble organic polymers are components that can be modified by mixing with clay minerals to form hydrophilic composite materials with the clay minerals. In the present invention, only one type selected from water-soluble organic polymers or clay minerals may be used, but both may be used in a mixture, and this is preferred.

[0058] Clay minerals such as bentonite or montmorillonite may be modified by pre-mixing with a water-soluble organic polymer. For example, the clay mineral and the water-soluble organic polymer may be uniformly mixed in water, and the mixture may then be dried, for example, by spray drying. The resulting dry mixture may be pulverized to a desired particle size, which may be in the range of 1 to 20 μm, if necessary. The amount of water-soluble polymer in such a mixture may be in the range of, for example, 0.1% to 40% by weight.

[0059] Examples of thickeners of the present invention include, but are not limited to, nanoclay, cellulose, polyacrylate, hydrophobically modified anionic thickeners, hydrophobically modified alkali swellable emulsions (HASE), and hydrophobically modified acrylic acid copolymers such as ACRYSOL® TT935 (Dow). The hydrophobically modified acrylic acid copolymer contains two or more hydrophobic groups, such as an aryl group, a phenyl group, or a C4 or higher alkyl group.

[0060] In some embodiments of the present invention, a thickening agent is first added to component (E) to produce thickened water (M). The total amount of the thickening agent may be in the range of 0.2 to 5 parts by weight, 0.5 to 5 parts by weight, 1 to 4 parts by weight, or 2 to 3 parts by weight, based on 100 parts by weight of component (E). If the amount of the thickening agent exceeds the above upper limit, the viscosity of the thickened water (M) may become too high, making it difficult to disperse the water in the silicone oil composite mixture (N), and reducing processability.

[0061] The thickening performance of the thickener is not particularly limited. However, from the perspective of the technical effects of the present invention, the thickened water (M) has a viscosity in the range of 5,000 to 1,000,000 cst, 20,000 to 800,000 cst, 50,000 to 500,000 cst, 100,000 to 300,000 cst, or 150,000 to 250,000 cst at 25°C and 0.1 s -1 and a thickening property having a viscosity in the range of 1,000 to 10,000 cst, 3,000 to 9,000 cst, 5,000 to 8,000 cst, or 6,000 to 7,000 cst at 25°C and 10 s -1 is preferably provided.

[0062] Component (G) In addition, in order to promote the dispersion of water droplets at a relatively small average bubble size and thereby maintain the consistency and homogeneity of the water-in-oil emulsion, one or more emulsifiers may be included. Similar to the thickener, the emulsifier can also improve the consistency, homogeneity, workability, and storage stability.

[0063] In a preferred embodiment, the emulsifier is a non-ionic emulsifier. In a more preferred embodiment, the emulsifier can be selected from the group consisting of polysiloxane polyethers, alkyl-poly(ethylene oxide), polyoxyethylene-polyoxypropylene copolymers, and mixtures thereof.

[0064] For example, the polyoxyethylene-polyoxypropylene copolymer non-ionic emulsifier is usually a compound represented by the following general formula (1) or general formula (2). HO(CH2CH2O) a (CH(CH3)CH2O) b (CH2CH2O) c H (1) HO(CH(CH3)CH2O) d (CH2CH2O) e (CH(CH3)CH2O) f H (2)

[0065] In general formulas (1) and (2), a, b, c, d, e, and f are the average number of moles of ethylene oxide or propylene oxide added, each independently ranging from 1 to 350. The weight-average molecular weight of the polyoxyethylene-polyoxypropylene copolymer is preferably 1,000 to 18,000, more preferably 1,500 to 10,000. Component (G), when in solid form, can be used in aqueous solution.

[0066] More specific examples of compounds that function as component (G) include the Pluronic® L series, Pluronic® P series, Pluronic® F series, and Pluronic® TR series from ADEKA CORPORATION, Emulgen PP-290 from Kao Corporation, and Newcol 3240 from Nippon Nyukazai Co., Ltd., all of which are commercially available.

[0067] In some embodiments of the present invention, emulsifier (G) does not contain an ionic emulsifier. Generally, anionic surfactants, cationic surfactants, and / or amphoteric surfactants can be used as ionic emulsifiers. Therefore, in the present invention, the curable silicone composition may be substantially free of surfactants. Examples of anionic surfactants include alkylbenzene sulfonates, alkyl ether sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, alkyl naphthyl sulfonates, unsaturated aliphatic sulfonates, and aliphatic hydroxylated sulfonates. Examples of cationic surfactants include quaternary ammonium type salt surfactants, such as octadecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and other alkyltrimethylammonium salts; dioctadecyldimethylammonium chloride, dihexadecyldimethylammonium chloride, didecyldimethylammonium chloride, and other dialkyldimethylammonium salts. Examples of amphoteric surfactants include alkyl betaines and alkylimidazolines.

[0068] In some embodiments of the present invention, an emulsifier is first added to the silicone oil composite mixture (N). The total amount of emulsifier may be in the range of 0.2 to 5 parts by weight, 0.5 to 5 parts by weight, 1 to 4 parts by weight, or 2 to 3 parts by weight, based on 100 parts by weight of component (A). If the amount of emulsifier exceeds the above upper limit, the mechanical strength of the final cured polysiloxane composition will decrease.

[0069] Ingredients (H) In the present invention, the hydrosilylation catalyst inhibitor is an optional component that can slow down the reaction rate by inhibiting the hydrosilylation catalyst as needed, thereby allowing the mixing to be completed before the mixture begins the curing reaction. Therefore, it should be understood that if curing does not occur rapidly during or immediately after mixing, it may be necessary to add component (H), but if curing can occur immediately after mixing, it may not be necessary to add component (H). The determination of whether or not it is necessary to add component (H) to the curable polysiloxane composition is within the capabilities of those skilled in the art.

[0070] Examples of hydrosilylation catalyst inhibitors include methylvinylcyclosiloxane, tetravinyltetramethyl-cyclotetrasiloxane (vinyl D4), ethinylcyclohexanol (ECH), and mixtures thereof. Particularly preferably, the hydrosilylation catalyst inhibitor may be incorporated into the curable polysiloxane composition in an amount sufficient to inhibit the hydrosilylation catalyst, for example, 0% to 2% by weight, 0.05% to 1.5% by weight, or 0.5% to 1.2% by weight, for example, 0.1% by weight, based on the total amount of the curable polysiloxane composition, and this depends on the desired curing rate.

[0071] In some embodiments of the present invention, the amount of component (H) is 0.05 to 2 parts by weight, 0.1 to 1.5 parts by weight, 0.5 to 1.0 parts by weight, or 0.7 to 0.9 parts by weight, based on 100 parts by weight of component (A).

[0072] Component (I) In the present invention, component (I) is one or more opacifying agents capable of absorbing, scattering, and reflecting thermal radiation. The particle sizes of these opacifying agents may be in the range of 0.2 to 50 μm, 0.5 to 20 μm, 1 to 10 μm, or 2 to 5 μm. Examples of opacifying agents include titanium dioxide, zirconium oxide, ilmenite, iron titanate, iron oxide, zirconium silicate, silicon carbide, manganese oxide, and carbon black, or any combination thereof. In one embodiment, carbon black or Fe3O4 may be used as the opacifying agent. Component (I) is typically present in an amount of 0.2 to 20% by weight, or 1 to 15% by weight, or 2 to 12% by weight, based on the total amount of the curable silicone composition. Component (I) is commercially available.

[0073] Process for producing polysiloxane composites from curable polysiloxane compositions The present invention also provides a process for producing a polysiloxane composite from the above-mentioned curable polysiloxane composition. The production process consists of the following steps: Step (I): A mixing step in which component (A) is mixed with other components (B), (C), (D), and optional components (H) and (I) to form a silicone oil composite mixture (N), then component (E) water is added, and the water is dispersed into droplets in the silicone oil composite mixture (N) by sufficient shearing and time, thereby producing a water-in-oil emulsion. Step (II): A heating step in which the water-in-oil emulsion prepared in Step (I) above is heated at a specific temperature and time sufficient to cure the silicone oil composite mixture (N) into a silicone matrix by the reaction of alkylene groups in component (A) and Si-H groups in component (B), thereby producing a cured wet composite in which water droplets are dispersed. Step (III): A drying step in which water is removed from the cured wet composite material prepared in Step (II) by raising the heating temperature to a level higher than the boiling point of water under the operating conditions and removing water from the cured wet composite material over a sufficient period of time, thereby obtaining a dry polysiloxane composite material. Includes.

[0074] Step (I) is a step of preparing a water-in-oil emulsion by dispersing component (E) water in droplets in a silicone oil composite mixture (N) of components (A), (B), (C), (D), and optional components (H) and (I). In some embodiments, step (I) is a step of introducing component (E) water into the silicone oil composite mixture (N) under conditions of mixing, or preferably mixing and shearing, mixing and stirring, or a combination of mixing, shearing, and stirring, to give a water-in-oil emulsion, wherein the droplets have an average droplet size of 100 μm or less, 80 μm or less, 50 μm or less, 30 μm or less, 10 μm or less, or 5 μm or less. Preferably, the average droplet size is 100 nm, 300 nm, 500 nm, 800 nm, or 1 μm or more.

[0075] In some preferred embodiments, before step (I), a thickened water (M) is prepared by adding a thickening agent (F) to water (E), and then, in step (I), the thickened water (M) is added to the silicone oil composite mixture (N) instead of water (E) to produce a water-in-oil emulsion.

[0076] In some more preferred embodiments, the viscosity of the silicone oil composite mixture (N) is 0.1s. -1 100-200,000 cst, 0.1s -1 300-150,000 cst, 0.1s -1 500-100,000 cst, 0.1s -1 1,000-80,000 cst, 0.1s -1 3,000 to 50,000 cst, or preferably 0.1 s -1 The viscosity ranges from 5,000 to 30,000 cst. In some further preferred embodiments, the viscosity ratio of the thickening water (M) to the silicone oil composite mixture (N) is 0.1s. -1 1 to 60, preferably 0.1s -1The range is 5 to 30. If both the viscosity of the silicone oil composite mixture (N) and the ratio of the viscosity of the thickening water (M) (or component (E) water) to the silicone oil composite mixture (N) are within the above range, the thickening water (M) (or component (E) water) can be easily dispersed into water droplets in the silicone oil composite mixture (N), thereby improving processability.

[0077] Step (II) is a step of curing the water-in-oil emulsion by reaction of alkylene groups with Si-H groups. In some embodiments, step (II) is a step of heating the water-in-oil emulsion prepared in step (I) at a temperature in the range of 50°C to 200°C for a period of time, for example, 5 minutes to 24 hours. However, in the present invention, the temperature and time are not particularly limited to the above range and can be determined as needed, as long as it is sufficient to cure the silicone oil composite mixture (N) into a silicone matrix through the reaction between the alkylene groups in component (A) and the Si-H groups in component (B). By curing, the water-in-oil emulsion forms a cured wet composite in which water droplets are dispersed. During curing, any technique to avoid significant water evaporation, such as a high-pressure and / or sealed reactor, can be used.

[0078] Step (III) is a step to obtain a dry polysiloxane composite by removing water from the cured wet composite prepared in step (II). That is, when curing is complete, the water can be removed from the cured wet composite by raising the operating temperature to a level higher than the boiling point of water and removing the water from the cured wet composite over a sufficient period of time. According to the process of the present invention, the dry polysiloxane composite obtained in step (III) can have an average bubble size of 100 μm or less. Due to such a smaller bubble size, the dry polysiloxane composite of the present invention can exhibit greatly improved thermal insulation performance at high temperatures.

[0079] In some embodiments, the dry polysiloxane composite obtained in step (III) may have a higher closed-cell ratio, for example, a closed-cell ratio of 50% or more. This higher closed-cell ratio allows the dry polysiloxane composite of the present invention to exhibit significantly improved thermal insulation performance at high temperatures.

[0080] Furthermore, since the dried polysiloxane composite material of the present invention is prepared by emulsification, curing, and drying processes rather than a chemical foaming process, its manufacturing process has process advantages such as being odorless and operator-friendly, and being safe to operate as it does not generate hydrogen gas.

[0081] Use of polysiloxane composite materials As described above, the polysiloxane composite material of the present invention and / or the polysiloxane composite material obtained by the manufacturing process of the present invention can significantly improve thermal insulation performance at high temperatures. Therefore, it can preferably be used as a thermal insulation material. For example, by applying the polysiloxane composite material of the present invention, which exhibits significantly improved thermal insulation performance at high temperatures, as a protective layer, it is possible to significantly delay external heat transfer to a substrate that needs to be protected in the event of a fire or explosion in the petroleum industry or electric vehicles. [Examples]

[0082] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. All parts and percentages are by weight unless otherwise indicated.

[0083] [density] The density of the polysiloxane composite was measured according to ASTM D792.

[0084] [Average bubble size] SEM images of polysiloxane composites were segmented using a deep learning-based segmentation method. Figures 2-7 show SEM images of Comparative Examples 1-2 (also abbreviated as "CE1" and "CE2," respectively) and Examples 1-4 of the present invention according to the present invention (also abbreviated as "IE1," "IE2," "IE3," and "IE4," respectively). This technique can accurately segment pores from a diverse range of image formats without requiring model retraining or parameter adjustment. The neural network used in this process is based on the U-Net architecture, and the model is trained on a dataset of over 70,000 segmented objects from a wide variety of microscopic images. The resulting model can generate masks featuring multiple labeled image regions. The scikit-image toolkit is used to analyze the masks and generate characteristics of the labeled image regions. The toolbox is built using Python 3.8 and depends on dependencies such as pytorch, numpy, scipy, and scikit-image. Further details can be found on the website titled "U-Net: Convolutional Networks for Biomedical Image Segmentation" at "https: / / arxiv.org / abs / 1505.04597v1".

[0085] [Tensile strength] The tensile strength of the polysiloxane composite material was measured according to CTM 0137A.

[0086] [stretch] The elongation of the polysiloxane composite was measured according to CTM 0137A.

[0087] [Thermal conductivity test] The thermal conductivity of the polysiloxane composite was tested using the so-called "comparative cut bar technique." Figure 1 shows this comparative cut bar technique. Specifically, since the heat flux passing through both samples is the same, the thermal conductivity can be calculated using Equation 1 by measuring the surface temperature and thickness of both samples.

[0088]

number

[0089] Here, the surface areas of the heat source, test specimen, and reference specimen are the same. The thermal conductivity of the test specimen is calculated using an insulating pad with a known thermal conductivity as the reference specimen. The reference specimen was a TOMBO 6702 sheet with a thickness of approximately 2 mm, obtained from Nichias Corporation in Japan, which provides stable thermal conductivity of 0.1 w / (m·k) at 400°C and 0.11 w / (m·k) at 600°C.

[0090] The heating test is continued for 20 minutes on one test sample. The values ​​of T1, T2, T3 and X1, X2 at 20 minutes are recorded, and the thermal conductivity λ is calculated. 試験 Used to calculate [something].

[0091] The raw materials used in the examples are listed in Table 1 below.

[0092] [Table 1]

[0093] [Examples 1-4 (IE1-4) and Comparative Examples 1-2 (CE1-2) of the present invention] In Examples 1 to 4 and Comparative Example 2 of the present invention, polysiloxane composites were produced using the raw materials and their quantities listed in Table 2. Comparative Example 1 is provided here as a control.

[0094] [Table 2]

[0095] [Table 3]

[0096] [Table 4]

[0097] Preparation of silicone composite formulations: Part A: All ingredients were mixed in a SpeedMixer at 1500 rpm for 2 minutes using a vacuum.

[0098] Part B: All ingredients were mixed under vacuum in a SpeedMixer at 1500 rpm for 2 minutes.

[0099] Part C: All components were mixed using a stirrer at 1500 rpm for 10 minutes.

[0100] Fabrication of polysiloxane composites: H2-foamed foam (CE1~2): Parts A and B were mixed using a Speedmixer at 1500 rpm for 30 seconds. The mixture was then poured between two PET films to form a sheet of the desired thickness. The sheet was cured and foamed in a 70°C oven for 10 minutes. The foamed silicone sheet was peeled from the PET film and post-cured in a 170°C oven for 30 minutes. After post-curing, the properties and performance of the polysiloxane composite sheet were measured.

[0101] Water-based silicone composites (IE1-4): Parts A and B were mixed using a Speedmixer at 1500 rpm for 30 seconds. Part C was then mixed into this mixture by hand and rapidly mixed under vacuum at 1500 rpm for 30 seconds. The mixture was then molded into a sheet of the desired thickness between two PET films. The sheet was cured in an 80°C oven for 10 minutes. The cured silicone composite was peeled from the PET film and dried in a 180°C oven for 60 minutes to remove water. After water removal, the properties and performance of the silicone composite were measured. The measurement results are shown in Table 3.

[0102] [Table 5]

[0103] As shown in Table 3, CE1-2 are conventional H2 foamed silicone foams with a cell size of 300-400 μm. Compared to IE1-4, which have a much smaller cell size, they have higher thermal conductivity measured at 600°C and worse thermal insulation performance.

[0104] In contrast, IE1-4 have lower thermal conductivity and better thermal insulation performance. On the other hand, due to their microcellular structure, their tensile strength is much higher than that of CE1-2. IE1-4 have a similar composition to CE2, but CE2 has much lower elongation.

Claims

1. A curable polysiloxane composition, (A) 100 parts by weight of at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, (B) 0.2 to 20 parts by weight of at least one organopolysiloxane having at least two hydrogen atoms bonded to silicon per molecule, (C) A catalytic amount of hydrosilylation catalyst, (D) At least one flame-retardant filler in an amount of 2 to 250 parts by weight, (E) Water and, A curable polysiloxane composition comprising, wherein component (E) water is dispersed as water droplets in a mixture of components (A), (B), (C), and (D), and the average droplet size is 100 μm or less.

2. (F) When at least one thickening agent is added to component (F) water, the resulting thickened water (M) is 0.1 s －１ 50,000 to 400,000 cst, 10s －１ The curable polysiloxane composition according to claim 1, further comprising in an amount having a viscosity in the range of 5,000 to 10,000 cst.

3. The curable polysiloxane composition according to claim 1 or 2, further comprising (H) at least one hydrosilylation catalyst inhibitor in an amount sufficient to inhibit the hydrosilylation catalyst.

4. (I) A curable polysiloxane composition according to any one of claims 1 to 3, further comprising at least one opacifying agent.

5. The curable polysiloxane composition according to any one of claims 1 to 4, wherein component (E) water is contained in an amount of 5 to 1,000 parts by weight per 100 parts by weight of the total amount of components (A), (B), (C), (D), (H), and (I).

6. The organopolysiloxane (A) is given by formula: 【Chemistry 1】 (In the formula, R ３ and R ４ R is selected from the group consisting of alkyl groups, phenyl groups, and vinyl groups, each having 1 to 6 carbon atoms per group. ４ A curable polysiloxane composition according to any one of claims 1 to 5, comprising a vinyl-terminated block polyorganosiloxane (of which at least 50% are methyl groups).

7. The curable polysiloxane composition according to any one of claims 1 to 6, wherein the organopolysiloxane (B) comprises a copolymer of trimethylsiloxy and methylhydrogen silicone, or a copolymer of trimethylsiloxy, methylhydrogen silicone, and dimethyl silicone.

8. The curable polysiloxane composition according to any one of claims 1 to 7, wherein the hydrosilylation catalyst (C) is selected from the group consisting of platinum, palladium, rhodium, nickel, iridium, ruthenium catalysts, and mixtures thereof.

9. The curable polysiloxane composition according to any one of claims 1 to 8, wherein the flame retardant filler (D) is selected from the group consisting of aluminum hydroxide, magnesium hydroxide, hydromagnesite, ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, and mixtures thereof.

10. The curable polysiloxane composition according to any one of claims 1 to 9, wherein the thickening agent (F) is selected from the group consisting of nanoclay, cellulose, polyacrylate, and mixtures thereof.

11. The curable polysiloxane composition according to any one of claims 1 to 10, wherein the hydrosilylation catalyst inhibitor (H) is selected from the group consisting of methylvinylcyclosiloxane, tetravinyltetramethyl-cyclotetrasiloxane (vinyl D4), ethynylcyclohexanol (ECH), and mixtures thereof.

12. The milky agent (I) is carbon black, Fe ３ O ４ A curable polysiloxane composition according to any one of claims 1 to 11, selected from the group consisting of the following: and mixtures thereof.

13. A process for producing a polysiloxane composite from a curable polysiloxane composition according to any one of claims 1 to 12, comprising the following steps, namely: Step (I): A mixing step in which component (A) is mixed with other components (B), (C), (D), and optional components (H) and (I) to form a silicone oil composite mixture (N), then component (E) water is added, and the water is dispersed into water droplets in the silicone oil composite mixture (N) over sufficient shearing and time, thereby producing a water-in-oil emulsion. Step (II): A heating step in which the water-in-oil emulsion prepared in step (I) above is heated at a specific temperature and time sufficient to cure the silicone oil composite mixture (N) into a silicone matrix by the reaction of alkylene groups in component (A) and Si-H groups in component (B), thereby producing a cured wet composite in which water droplets are dispersed. Step (III): A drying step in which water is removed from the cured composite material produced in Step (II) by raising the heating temperature to a level higher than the boiling point of water under the operating conditions and removing water from the cured wet composite material over a sufficient period of time, thereby obtaining a dry polysiloxane composite material. A process that includes this.

14. The manufacturing process according to claim 13, wherein, before step (I), thickened water (M) is prepared in advance by adding component (F) a thickening agent to component (E) water, and then, in step (I), the thickened water (M) is added to the silicone oil composite mixture (N) instead of component (E) water to produce a water-in-oil emulsion.

15. The manufacturing process according to claim 13 or 14, wherein the silicone oil composite mixture (N) further comprises (H) at least one hydrosilylation catalyst inhibitor and / or (I) at least one opacifying agent.

16. The manufacturing process according to any one of claims 13 to 15, wherein the average bubble size of the dried polysiloxane composite obtained in step (III) is 100 μm or less.

17. Use of the polysiloxane composite material obtained by the manufacturing process described in any one of claims 13 to 16 as a thermal insulation material.

18. An article comprising the polysiloxane composite material obtained by the manufacturing process described in any one of claims 13 to 16.

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