CN111902472A

CN111902472A - Hydrophobic organic aerogels based on epoxy-isocyanate polymer networks

Info

Publication number: CN111902472A
Application number: CN201980022179.1A
Authority: CN
Inventors: B·德尔萨兹-奥罗斯科罗德里格斯; I·德桑托; A·萨卡里特; E·托里斯卡诺; F·萨尔希
Original assignee: Henkel AG and Co KGaA; Henkel IP and Holding GmbH
Current assignee: Henkel AG and Co KGaA; Henkel IP and Holding GmbH
Priority date: 2018-03-28
Filing date: 2019-01-10
Publication date: 2020-11-06
Also published as: WO2019185207A1

Abstract

The present invention relates to a hydrophobic organic aerogel obtained by reacting an isocyanate compound with an epoxy compound in the presence of a solvent. The aerogels according to the invention are hydrophobic high performance materials (lightweight, with low thermal conductivity, low shrinkage and high mechanical properties).

Description

Hydrophobic organic aerogels based on epoxy-isocyanate polymer networks

Technical Field

Background

Aerogels are three-dimensional low-density assemblies of nanoparticles obtained by drying wet gels, usually with supercritical fluids, by replacing the pore-filling solvent with a gas. In these ways, the capillary forces exerted by the solvent due to evaporation are minimized and a structure with large internal void spaces is achieved. The high porosity and small pore size of these materials are the reason for their very low thermal conductivity, making aerogels an attractive material for thermal insulation applications.

Aerogel is a lightweight material with very low thermal conductivity compared to common thermal insulation on the market. Aerogels are therefore known as good insulating materials due to their nanostructure. Therefore, the thickness of the insulating layer can be reduced while obtaining similar insulating characteristics. Aerogels are environmentally friendly because they are air-filled and, in addition, they are not susceptible to aging.

Thermal insulation is important in many different applications in order to save energy and reduce costs. Examples of such applications are construction, transportation and industry. For some applications, thick insulating plates may be used to reduce heat transfer. However, other applications may require thinner insulating panels/layers due to size limitations. For thin insulating plates/layers, the thermal conductivity of the material must be very low in order to achieve the same insulating properties as thicker insulating plates/layers. In addition, in some cases and depending on the application, high mechanical properties may also be required.

Most known aerogels are inorganic aerogels based primarily on silica, although different organic aerogels have also been described in the literature.

Inorganic silica aerogel provides high thermal insulation properties; however, they are brittle and have poor mechanical properties. These low mechanical properties are generally attributed to well-defined narrow interparticle necks. The friability problem of silica can be solved by different methods: by crosslinking the aerogel with an organic polymer or by post-gelling a thin conformal polymer coating (post-gelation) cast over the entire internal porous surface of the preformed wet gel nanostructure.

Inorganic silica aerogels represent the most traditional type and provide the best thermal insulation properties. However, these materials are brittle, dusty and easily airborne and therefore cannot withstand mechanical stress. Because of this, they are sometimes classified as hazardous materials. In addition, because of their brittleness, they are not suitable for use in some applications where mechanical properties are required.

The first organic aerogels described in the literature are based on phenolic resins. Typically, organic aerogels are not brittle materials. They are based on different classes of polymer networks formed by crosslinking monomers in solution to produce a gel, which is subsequently dried to obtain a porous material. A considerable number of organic aerogels are based on materials prepared using polyfunctional isocyanates. Various isocyanate monomers can be used to prepare polyimide aerogels (by reaction with an anhydride), polyamide aerogels (by reaction with a carboxylic acid), polyurethane aerogels (by reaction with a hydroxylated compound), polycarbodiimide aerogels or polyurea aerogels (by reaction with an aminated compound or with water as a catalyst).

The polyurethane aerogel may be obtained by reacting a cyclic ether-based resin with a polyisocyanate, and then drying it by supercritical drying. These aerogels exhibit low thermal conductivity and good mechanical properties. However, these materials are generally not hydrophobic.

Both inorganic and organic aerogels are generally hydrophilic. To improve the hydrophobicity of the aerogel, the surface of the aerogel may be hydrophobized by using a modification solution, wherein the surface groups may be replaced by hydrophobic groups, typically Trimethylsilyl (TMS). The TMS group is most often introduced by a Trimethylchlorosilane (TMCS), Hexamethyldisilazane (HMDZ), or Hexamethyldisiloxane (HMDSO) hydrophobizing agent. A more direct alternative route to open-celled hydrophobic materials is to use precursors comprising chemically bonded hydrophobic groups, such as methyltrimethoxysilane/methyltriethoxysilane (MTMS/MTES) or dimethyldimethoxysilane (DMDMS). In addition, crosslinking is another method for improving the water resistance of aerogels through substitution of hydrophilic groups and formation of a three-dimensional network. However, the addition of a crosslinking agent increases the production cost. Surface coating by forming a rigid hydrophobic layer on the surface of the aerogel can also be used to improve the compressive strength and water resistance of the aerogel. However, all of these methods are disadvantageous due to the additional step after gel formation during the material preparation.

Thus, there remains a need for organic aerogels that are hydrophobic and have good stability to moisture while maintaining good mechanical properties as well as thermal conductivity.

Drawings

Figure 1 illustrates the improved hydrophobicity of aerogels according to the present invention.

Fig. 2 illustrates contact angle (θ) measurements.

Disclosure of Invention

The present invention relates to a hydrophobic organic aerogel obtained by reacting an isocyanate compound having a functionality of from 2 to 6 with an epoxy compound having a functionality of from 2 to 6 in the presence of a solvent, wherein the isocyanate compound is selected from:

wherein a is an integer from 1 to 30;

wherein b is an integer from 1 to 30;

wherein c is an integer from 1 to 30;

wherein X represents the same substituent (a) or different substituents and is independently selected from hydrogen, halogen and linear or branched C1-C6 alkyl and their corresponding isomers attached at the 2-, 3-or 4-position on their respective phenyl rings, and R¹Selected from the group consisting of singly bonded-O-, -S-, -C (O) -, -S (O)₂-、-S(PO₃) -, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted C7-C30 alkylaryl, substituted or unsubstituted C3-C30 heterocycloalkyl, and substituted or unsubstituted C1-C30 heteroalkyl, and combinations thereof;

wherein R is²Independently selected from alkyl, hydrogen and alkenyl, Y is selected from

And d is an integer from 0 to 3;

and mixtures thereof;

and wherein the epoxy compound is selected from:

wherein e¹、e²、e³The same or different and independently selected from 1 to 12; f. of¹、f²、f³Are the same or different and are independently selectedFrom 1 to 12; g¹、g²、g³The same or different and independently selected from 1 to 26; h is¹、h²、h³Are the same or different and are independently selected from 0 to 6, with the proviso that h¹+h²+h³At least 2; i.e. i¹、i²、i³The same or different and independently selected from 0 to 25; j is a function of¹、j²、j³The same or different and independently selected from 1 to 26; k is a radical of¹、k²、k³Are the same or different and are independently selected from 0 to 6, provided that k is¹+k²+k³At least 2; l¹、l²、l³The same or different and independently selected from 0 to 25;

wherein R is³Represent the same substituent or different substituents and are independently selected from hydrogen, halogen and linear or branched C1-C15 alkyl or alkenyl and their corresponding isomers attached at the 3-, 4-or 5-position on their respective phenyl rings, and m is an integer from 1 to 5; wherein n and o are the same or different and are independently selected from 1 to 10;

wherein p is an integer from 1 to 5;

and mixtures thereof.

The invention also relates to a process for preparing the hydrophobic organic aerogels according to the invention, comprising the following steps: 1) dissolving an epoxy compound in a solvent, adding an isocyanate compound and mixing; 2) adding catalyst, if present, and mixing; 3) allowing the mixture to stand to form a gel; 4) washing the gel with a solvent; and 5) drying the gel by supercritical or ambient drying.

The present invention encompasses thermal or acoustic insulation materials comprising the hydrophobic organic aerogel according to the present invention.

The invention also encompasses the use of the hydrophobic organic aerogels according to the invention as thermal or acoustic insulation material.

Detailed Description

In the following paragraphs, the present invention is described in more detail. Each aspect so described may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

In the context of the present invention, the terms used should be construed according to the following definitions, unless the context indicates otherwise.

As used herein, the singular forms "a", "an", "the" and "the" include both singular and plural referents unless the context clearly dictates otherwise.

As used herein, the terms "comprising" and "comprises," which are synonymous with "including" or "containing," are inclusive or open-ended and do not exclude additional unrecited members, elements, or method steps.

The recitation of numerical endpoints includes all numbers and fractions subsumed within the corresponding range and the recited endpoints.

All percentages, parts, ratios, etc., referred to herein are by weight unless otherwise indicated.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as upper and lower preferable values, it is to be understood that any range obtained by combining any upper value or preferred value with any lower value or preferred value is specifically disclosed, regardless of whether the obtained range is clearly referred to in the context.

All references cited in this specification are herein incorporated by reference in their entirety.

Unless defined otherwise, all terms (including technical and scientific terms) used in disclosing the invention have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. By way of further guidance, definitions of terms are included to better understand the teachings of the present invention.

The term "aerogel" refers herein to a synthetic porous low density material derived from a gel in which a gas has replaced the liquid component of the gel. These materials typically exhibit low thermal conductivity due to their porosity and density.

The term "gel" refers herein to a solid jelly-like soft material with a substantially (substitially) diluted cross-linked system that exhibits no flow when in a steady state.

The present invention relates to hydrophobic organic aerogels obtained by reacting isocyanate compounds with epoxy compounds. The reaction of the isocyanate with the epoxy groups makes it possible to prepare a polymer network having a high degree of crosslinking, due to the polymerization mechanism of the epoxy resin. A high degree of crosslinking results in lower pore size and better mechanical properties compared to materials with a lower degree of crosslinking. Given the reactivity of these functional groups, the resulting aerogels can have different connectivity.

The main reactions that can take place between isocyanates and epoxides are illustrated in scheme 1 as representative examples. Urea (a) is formed in the reaction between isocyanate and water. The carbamate (b) is obtained in the reaction between isocyanate and alkoxide after epoxide ring opening. Trimerization of isocyanates leads to the formation of isocyanurates (c). Oxazolidinone (d) is obtained in the reaction between isocyanate and epoxy resin at high temperature.

Scheme 1

The resulting nanoporous network may thus comprise polyurethane (b), polyisocyanurate (c) and polyoxazolidone (d), and to a lesser extent polyurea (a). The hydrophobic organic aerogels according to the invention have a high degree of crosslinking, a lower pore size and better mechanical properties compared to aerogels with a lower degree of crosslinking.

The present invention relates to a hydrophobic organic aerogel obtained by reacting an isocyanate compound having a functionality of 2 to 6 with an epoxy compound having a functionality of 2 to 6 in the presence of a solvent.

The hydrophobic organic aerogel according to the present invention has improved hydrophobicity and good water resistance characteristics. Furthermore, the hydrophobic organic aerogel according to the invention is lightweight, has low thermal conductivity, low shrinkage and good mechanical properties.

The hydrophobic organic aerogel is obtained by reacting an isocyanate compound with an epoxy compound.

Suitable isocyanate compounds for use in the present invention are aliphatic or aromatic isocyanates selected from the group consisting of:

wherein a is an integer from 1 to 30;

wherein b is an integer from 1 to 30;

wherein c is an integer from 1 to 30;

wherein X represents the same substituent or different substituents and is independently selected from hydrogen, halogen and linear or branched C1-C6 alkyl and their corresponding isomers attached at the 2-, 3-or 4-position on their respective phenyl rings, and R¹Selected from the group consisting of singly bonded-O-, -S-, -C (O) -, -S (O)₂-、-S(PO₃) -, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted C7-C30 alkylaryl, substituted or unsubstituted C3-C30 heterocycloalkyl, and substituted or unsubstituted C1-C30 heteroalkyl, and combinations thereof;

And

d is an integer of 0 to 3;

and mixtures thereof.

Preferably, the isocyanate compound is selected from the group consisting of 3,5-bis (6-isocyanatohexyl) -6- (6-isocyanatohexylimino) -1,3, 5-oxadiazine-2, 4-dione (3,5-bis (6-isocyanatohexynyl) -6- (6-isocyanatohexylimino) -1,3, 5-oxadiazine-2, 4-dione), 1,3-bis [ p- ({ p- [3,5-bis (3-isocyanatotolyl) -2,4,6-trioxo-1,3, 5-triazacyclohexan-1-yl ] phenyl } methyl) phenyl ] -5- (3-isocyanatotolyl) -1,3, 5-triazacyclohexan-2, 4,6-trione (1,3-bis [ p- ({ p- [3,5-bis (3-isocyanato tolyl) -2,4,6-trioxo-1,3,5-triazinan-1-yl ] phenyl } methyl) phenyl ] -5- (3-isocyanatoolol) -1,3, 5-triazinan-2, 4,6-trione), 4' -diphenylmethane diisocyanate, 1,3, 5-tris (6-isocyanatohexyl) -1,3, 5-triazacyclohexane-2, 4,6-trione, 1,3-bis (6-isocyanatohexyl) -1- (6-isocyanatohexylcarbamoyl) urea, 6- [3- (6-isocyanatohexyl) -2, 4-dioxo-1, 3-diazetidin-1-yl ] hexyl N- (6-isocyanatohexyl) carbamate, 1- [ bis (4-isocyanatophenyl) methyl ] -4-isocyanatobenzene and mixtures thereof.

The preferred isocyanate compounds listed above are preferred because they provide aerogels with optimal properties.

Examples of commercially available isocyanate compounds for use in the present invention include, but are not limited to: desmodur N3300, Desmodur N3400, Desmodur N3600, Desmodur N3900, Desmodur N3200, Desmodur44V, Desmodur RE, Desmodur IL from Covestro; wannate HT 100 from wanhua; diphenylmethane 4,4' -diisocyanate (MDI) from Merck; and VORASTAR HB 6042 from Dow Chemical Company.

The hydrophobic organic aerogel according to the present invention has an isocyanate compound content of 0.2 to 56% by weight, preferably 0.3 to 45% by weight and more preferably 0.5 to 35% by weight, based on the total weight of the reaction mixture (including the solvent).

If the content of the isocyanate compound is more than 56%, an aerogel having a high density and a high thermal conductivity will be obtained. These are not the desired characteristics of the aerogel according to the invention.

Suitable epoxy compounds for use in the present invention are long chain aliphatic epoxy compounds or aromatic epoxy compounds.

Suitable epoxy compounds for use in the present invention are selected from:

wherein e¹、e²、e³The same or different and independently selected from 1 to 12; f. of¹、f²、f³The same or different and independently selected from 1 to 12; g¹、g²、g³The same or different and independently selected from 1 to 26; h is¹、h²、h³Are the same or different and are independently selected from 0 to 6, with the proviso that h¹+h²+h³At least 2; i.e. i¹、i²、i³The same or different and independently selected from 0 to 25; j is a function of¹、j²、j³The same or different and independently selected from 1 to 26; k is a radical of¹、k²、k³Are the same or different and are independently selected from 0 to 6, provided that k is¹+k²+k³At least 2; l¹、l²、l³The same or different and independently selected from 0 to 25;

wherein p is an integer from 1 to 5;

and mixtures thereof.

Preferably, the epoxy compound is selected from the group consisting of 2- [ (3- { [ 2-hydroxy-3- ({2- [ (2-epoxyethyl) methoxy ] -4-pentadecylphenyl } methyl) -4-pentadecylphenyl ] methyl } -2- [ (2-epoxyethyl) methoxy ] -4-pentadecylphenyl) methyl ] -6- ({2- [ (2-epoxyethyl) methoxy ] -6-pentadecylphenyl } methyl) -3-pentadecylphenol, 2, 3-bis { (E) -11- [ (2-epoxyethyl) methoxy ] -8-heptadecenylcarbonyloxy } propyl (E) -12- [ (2-epoxyethyl) methoxy ] -9-octadecenoate, enoate, 2- { [ m- (8- { p- [ (2-epoxyethyl) methoxy ] phenyl } pentadecyl) phenoxy ] methyl } oxirane, tris (2, 3-epoxypropyl) isocyanurate, 2, 3-bis (2- {3- [2- (3-propyl-2-epoxyethyl) ethyl ] -2-epoxyethyl } propionyloxy) propyl 3- {3- [2- (3-propyl-2-epoxyethyl) ethyl ] -2-epoxyethyl } propanoate, a polymer with 2- ({3- [ (3-methoxy-1-naphthyl) methyl ] tolyloxy } methyl) oxirane, 7-oxabicyclo [4.1.0] hept-3-ylmethyl 7-oxabicyclo [4.1.0] heptane-3-carboxylate, a salt of a compound of formula I, Phenol polymers with 3a,4,7,7 a-tetrahydro-4, 7-methylene-1H-indene glycidyl ether and mixtures thereof.

The preferred epoxy compounds listed above are preferred because they provide hydrophobic aerogels.

Examples of commercially available epoxy compounds for use in the present invention include, but are not limited to: cardolite NC-547, Cardolite NC-514S and Cardolite NC-514 from Cardolite; erisys GE35 from CVC cultures; CER 4221 from DKSH; vikoflex 7170 and Vikoflex 7190 from Arkema; epiclon HP-5000, Epiclon HP-7200H and Epiclon HP-9500 from DIC Corporation; jagroxy-505 from Jayantgaro-Organics Ltd; and KR-470, X-12-981S, KR-517, KR-516, X-41-1059A and X-24-9590 from Shin Etsu.

The hydrophobic organic aerogels according to the invention have an epoxy compound content of from 0.7 to 60% by weight, preferably from 1 to 40% by weight and more preferably from 1.5 to 20% by weight, based on the total weight of the reaction mixture (including solvent).

If the amount of epoxy compound is above 60%, gelation is very slow, while an amount less than 0.7% will result in precipitation and heterogeneous gel.

In the hydrophobic organic aerogel according to the present invention, the ratio of epoxy groups to isocyanate groups is from 1:15 to 5:1, preferably from 1:8 to 3:1, and more preferably from 1:6 to 2: 1.

When the ratio of epoxy groups to isocyanate groups is less than 1:15, a significant amount of unreacted isocyanate monomer will be present in the reaction mixture. On the other hand, when the ratio of epoxy groups to isocyanate groups is higher than 5:1, gelation does not occur. The preferred ratio range of 1:6 to 2:1 provides aerogels with the best performance.

The hydrophobic organic aerogel is obtained by reacting an isocyanate compound with an epoxy compound in the presence of a solvent.

Suitable solvents to be used in the present invention are polar solvents, preferably polar aprotic solvents. Preferably, the solvent is selected from the group consisting of N, N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), acetonitrile, acetone, Methyl Ethyl Ketone (MEK), 4-methyl-2-pentanone (MIBK), and mixtures thereof.

The preferred solvents listed above are preferred because they provide aerogels with the best performance.

Examples of commercially available solvents for use in the present invention include, but are not limited to: n, N-dimethylacetamide from Merck Millipore, 1-methyl-2-pyrrolidone (NMP), Dimethylsulfoxide (DMSO), and acetonitrile; 4-methyl-2-pentanone (MIBK), Methyl Ethyl Ketone (MEK) from AlfaAesar; and acetone from VWR Chemicals.

In one embodiment according to the present invention, the hydrophobic organic aerogel may be obtained by reacting an isocyanate compound with an epoxy compound in the presence of a catalyst.

Suitable catalysts for use in the present invention are selected from alkylamines, aromatic amines, imidazole derivatives, aza compounds, guanidine derivatives and amidines, preferably selected from triethylamine, trimethylamine, N-dimethylbenzylamine, 1, 4-diazabicyclo [2.2.2] octane, 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU), 1,5, 7-triazabicyclo [4.4.0] dec-5-ene (TBD), dibutyltin dilaurate and mixtures thereof.

The preferred catalysts mentioned above are preferred because they provide faster gelling and require lower temperatures for this purpose.

Examples of commercially available catalysts for use in the present invention include, but are not limited to: triethylamine, trimethylamine, diazabicyclo [5.4.0] undec-7-ene (DBU), 1,5, 7-triazabicyclo [4.4.0] dec-5-ene (TBD), Dabco 33V and dibutyltin dilaurate (DBTDL) from Sigma Aldrich, N-dimethylbenzylamine from Merck Millipore, 1, 4-diazabicyclo [2.2.2] octane from Alfa Aesar.

The catalyst is added in an amount of 0 to 10 wt%, preferably 1 to 10 wt% and more preferably 1.5 to 10 wt%, based on the total weight of the reaction mixture (including the solvent).

The range of 1.5 to 10% is preferred because aerogel performance levels off near 10% catalyst and higher catalyst levels do not improve any properties beyond this point.

In one embodiment, the hydrophobic organic aerogel according to the present invention further comprises at least one reinforcing material or filler.

Suitable reinforcing materials or fillers for use in the present invention are selected from the group consisting of fibers, particles, fabrics and mats (mat), 3D structures and mixtures thereof.

Non-limiting examples of suitable fibers are cellulose, aramid, carbon, glass, and lignocellulosic fibers.

Non-limiting examples of suitable particles are carbon black, microcrystalline cellulose, silica, cork, lignin and aerogel particles.

Non-limiting examples of suitable fibrous fabrics and mats are non-woven and woven glass, aramid, carbon, and lignocellulosic fibrous fabrics.

Non-limiting examples of suitable 3D structures are aramid fiber-phenolic resin, glass fiber-phenolic resin, polycarbonate and polypropylene honeycomb structures, and 3D printed structures.

In a preferred embodiment, the at least one reinforcing material or filler is selected from: cellulosic fibers, aramid fibers, carbon fibers, glass fibers, lignocellulosic fibers, glass wool, carbon black, microcrystalline cellulose, silica particles, cork particles, lignin particles, aerogel particles, non-woven and woven glass fiber fabrics, aramid fiber fabrics, carbon fiber fabrics, jute fiber fabrics, flax fiber fabrics, aramid fiber-phenolic resin honeycomb structures, glass fiber-phenolic resin honeycomb structures, polycarbonate honeycomb structures, polypropylene honeycomb structures, and mixtures thereof; more preferably, the at least one reinforcing material or filler is selected from: cellulosic fibers, aramid fibers, carbon fibers, glass wool, carbon black, microcrystalline cellulose, nonwoven glass fiber fabrics, woven aramid fiber fabrics, woven jute fiber fabrics, woven flax fiber fabrics, aramid fiber-phenolic resin honeycomb structures, glass fiber-phenolic resins, cardboard honeycomb structures, polypropylene honeycomb structures, and mixtures thereof.

Examples of commercially available reinforcing materials for use in the present invention include, but are not limited toWithout limitation: acros Organics microcrystalline cellulose, alpha-cellulose Sigma Aldrich powder, MT1100, IC3120 and P300 silica aerogel particles from Cabot, CSX 691 carbon black from Cabot, Procotex aramid fiber, Procotex CF-MLD100-13010 carbon fiber, E-glass Vetrotex textile fiber EC 9134 z 28T 6M ECG 371/00.7 z,

U809

glass fibers, Composites Evolution Biotex jute plain weave, Composites Evolution Biotex flax 2/2 twill weave, Easycomposites aramid cloth satin weave, Euro-Composites ecg glass fiber-phenolic resin honeycomb, Euro-Composites ECAI aramid fiber-phenolic resin honeycomb, easycosites aramid fiber-phenolic resin honeycomb, Cel Composites algalolar PP8-80T 303D, Cel Composites alveolate 3.5-903D structure, polypropylene honeycomb from tubushbahu, fiberglass chopped strand mat from easycosites, Thermex PEI honeycomb from Econcore, Thermex PP honeycomb from thievesse, PU 3D printed structure from tuftingrse, cardboard honeycomb from Unifrax and glass microfiber.

Depending on the reinforcing material incorporated in the hydrophobic organic aerogel according to the invention, the percentage of reinforcing material or filler in the final material can vary from 0.01% to 80%, preferably from 0.5 to 70%, based on the total weight of the initial solvent.

The hydrophobic organic aerogels according to the invention have a solids content of from 4 to 40%, preferably from 5 to 30%, based on the initial solids content of the solution.

A solids content in the range of 4 to 40% is desirable as it provides a good compromise between thermal and mechanical properties. High solids content provides high mechanical properties; however, high solids content provides poor insulation properties. On the other hand, low solids content provides lower thermal conductivity, but the mechanical properties are not ideal.

The hydrophobic organic aerogels according to the invention have a thermal conductivity of less than 60 mW/m-K, preferably less than 55 mW/m-K, more preferably less than 50 mW/m-K, and even more preferably less than 45 mW/m-K. Thermal conductivity can be measured using either the diffusivity sensor method or the steady state condition system method, depending on whether the material being tested is on a laboratory scale or a larger scale.

Diffusivity sensor method

In this method, the thermal conductivity is measured by using a diffusivity sensor. In this method, the heat source is located on the same side of the device as the measurement sensor. The sensor measures heat diffused from the sensor throughout the material. The method is suitable for laboratory scale tests.

Steady state condition system method

In this method, thermal conductivity is measured using a steady state condition system. In this method, a sample is sandwiched between a heat source and a heat sink. Temperature rises on one side, heat flows through the material; once the temperature on the other side is constant, the heat flux versus temperature difference is known; the thermal conductivity can be measured.

The hydrophobic organic aerogels according to the invention have a young's modulus under compression, measured according to method ASTM D1621, of greater than 0.1MPa, preferably greater than 15MPa, and more preferably greater than 30 MPa.

The organic aerogel according to the invention preferably has a compressive strength greater than 0.01MPa, more preferably greater than 0.45MPa and even more preferably greater than 1 MPa. Compressive strength was measured according to standard ASTM D1621.

The organic aerogels according to the invention preferably have a thickness of between 5m²G to 400m²Specific surface area in the range of/g. Surface area was determined by N-196 ℃ in a specific surface analyzer Quantachrome-6B using the Brunauer-Emmett-Teller (BET) method₂Adsorption analysis.

High surface area values are preferred because they represent small pore sizes and they may represent low thermal conductivity values.

According toThe organic aerogel of the present invention preferably has an average pore diameter in the range of 5 to 80 nm. By applying to the signal from the pass N₂The adsorption analysis measured the Barret-Joyner-Halenda (BJH) model of the desorption branch of the isotherm to calculate the pore size distribution. The average pore diameter is determined by applying the following equation: average pore diameter ═ (4 × V/SA), where V is total pore volume and SA is the surface area calculated from BJH. The porosity of the sample can also be assessed by He pycnometry.

Aerogel pore diameters below the mean free path of the air molecules (which is 70nm) are desirable because this makes it possible to obtain high performance insulating aerogels with very low thermal conductivity values.

The hydrophobic organic aerogel according to the present invention has a low-density structure with a bulk density in the range of 0.01 to 0.8 g/cc. Bulk density is calculated from the weight of the dry aerogel and its volume.

The hydrophobic organic aerogel according to the present invention is resistant to low temperature exposure (-160 ℃). In addition, hydrophobic organic aerogels are resistant to liquid nitrogen impregnation (-196℃.) and subsequent volatilization.

Water penetrates the surface of the hydrophilic aerogel and the aerogel breaks. However, hydrophobic aerogels are resistant to water without breaking. The aerogels according to the invention have improved hydrophobicity and water resistance. This is illustrated in fig. 1. Water droplets are located on top of the aerogel-figure 1a illustrates an aerogel as described in WO2017016755a1, wherein bisphenol a-DGE is used as the epoxy compound; while fig. 1b and 1c illustrate hydrophobic aerogels according to the invention, using Erisys GE35(1b) and Cardolite NC-547(1c) as epoxy compounds. As is clear from fig. 1a and 1b/1c, the aerogels according to the invention repel water droplets, which apparently remain as micro-droplets on the surface of the aerogel. However, aerogels according to the prior art do not repel water droplets as strongly and some water penetrates the surface of the aerogel.

The hydrophobic organic aerogels according to the present invention preferably have a water contact angle higher than 90 °. Wettability is quantified by measuring the contact angle (θ) between the tangent line at the intersection of a water droplet with the surface and the surface itself. The contact angle (θ) measurements are illustrated in fig. 2. Fig. 2a is a theoretical illustration and fig. 2b is an illustration of an example according to the invention. Generally, a solid surface is considered hydrophobic if the water contact angle is above 90 °. Contact angle measurements can be made by using an EasyDrop contact Angle measuring instrument (Kruss GmbH) in static mode and 10. mu.l of a water drop.

In order to prepare the hydrophobic organic aerogels according to the present invention, several aspects must be considered. The functionality equivalent ratio, initial solids content, amount and type of catalyst (if present), type of solvent, gel time and temperature are critical factors that affect the final properties of the material.

In one embodiment, the hydrophobic organic aerogel according to the present invention can be prepared by using a method comprising the steps of:

1) dissolving an epoxy compound in a solvent, adding an isocyanate compound and mixing;

2) adding catalyst, if present, and mixing;

3) allowing the mixture to stand to form a gel;

4) washing the gel with a solvent; and

5) the gel is dried by supercritical or ambient drying.

The reaction mixture was prepared in a closed vessel.

The gelling step (3) is carried out in a closed mould to achieve a preset time and temperature. Preferably, the temperature is applied in step 3, more preferably, a temperature from room temperature to 160 ℃ is applied at the time of gel formation, and most preferably, a temperature from room temperature to 80 ℃.

Temperatures from room temperature to 160 ℃ are preferred because of the best performing aerogels.

The gel time is preferably 0.5 to 48 hours, more preferably 1 to 36 hours, and even more preferably 1 to 24 hours.

The washing time in step (4) is preferably 1 hour to 72 hours, preferably 18 hours to 72 hours, and more preferably 24 hours to 48 hours.

After gelling, changingAnd (3) dissolving the wet gel in one or more times. In some embodiments, the washing step is performed stepwise, and if necessary, stepwise to the preferred solvent for the drying process. Once the wet gel is maintained in a suitable solvent, it is supercritical (CO)₂) Or dried at ambient conditions to obtain the final aerogel material.

In one embodiment, the washing step is performed stepwise as follows: 1) acetone/DMAc 1: 3; 2) acetone/DMAc 1: 1; 3) acetone/DMAc 3: 1; and 4) acetone. In another embodiment, the washing step is performed with acetone. In another embodiment, all four washing steps are performed stepwise with hexane. Once the solvent was completely replaced by acetone, the gel was placed in supercritical (CO)₂) Or dried at ambient conditions to obtain the final aerogel material.

The supercritical state of a substance is reached once the liquid and gas phases of the substance become indistinguishable. The pressure and temperature at which the material enters this stage is called the critical point. In this phase, the fluid exhibits a low viscosity of the gas while maintaining a higher density of the liquid. It can flow out through a solid like a gas and dissolve material like a liquid. In view of the aerogel, once the liquid within the pores of the wet gel reaches the supercritical phase, its molecules do not possess sufficient intermolecular forces to develop the surface tension necessary to create capillary stress. Thus, the solvent can be dried while minimizing shrinkage and possible collapse of the gel network.

Drying under supercritical conditions by using CO in its supercritical state₂Or other suitable solvent to displace the solvent in the gel. Due to this, the capillary forces exerted by the solvent during evaporation in the nanopore are minimized and the shrinkage of the gel may be reduced.

In one embodiment, the method for preparing a hydrophobic organic aerogel comprises recovering CO from the supercritical drying step₂。

Alternatively, the wet gel may be dried at ambient conditions, wherein the solvent is allowed to evaporate at room temperature. However, as the liquid evaporates from the well, it can form a meniscus that recedes into the gel due to the difference between the interfacial energies. This can create capillary stress on the gel, which responds by shrinking. If these forces are high enough, they may even lead to collapse or fracture of the entire structure. However, there are different possibilities to minimize this phenomenon. One practical solution involves the use of solvents with low surface tension to minimize the interface energy between the liquid and the pores. Unfortunately, not all solvents lead to gelation, which means that some cases require solvent replacement between the initial solvent required for gel formation and the second solvent most suitable for the drying process. Hexane is generally used as a convenient solvent for ambient drying because its surface tension is the lowest of the conventional solvents.

The hydrophobic organic aerogel according to the present invention can be used as a thermal or acoustic insulation material.

In a highly preferred embodiment, the hydrophobic organic aerogels according to the present invention can be used as thermal insulation materials for the storage of refrigerants.

The hydrophobic organic aerogels according to the invention can be used in various applications such as building construction, electronic engineering or in the aerospace industry. The hydrophobic organic aerogel may be used as an insulating material for refrigerators, freezers, automobile engines, and electronic devices. Other potential applications of aerogels are as sound absorbers and catalyst supports.

The hydrophobic organic aerogels according to the invention can be used for thermal insulation in the following applications: in various applications such as aircraft, spacecraft, pipelines, tankers and marine vessels, in automotive battery housings and under-hood liners, in lamps, in cold-pack technology (including cans and boxes), jackets and shoes, and tents, instead of foam boards and other foam products currently used.

The hydrophobic organic aerogel according to the present invention can also be used in building materials due to its light weight, strength, ability to be formed into a desired shape, and excellent heat insulation characteristics.

The hydrophobic organic aerogels according to the present invention can also be used as thermal insulation for storage and transportation of refrigerants.

The hydrophobic organic aerogel according to the present invention can also be used as an adsorbent for oil spill cleanup due to its high oil absorption.

The hydrophobic organic aerogel according to the present invention can also be used as a shock-absorbing medium in safety and protection devices.

Examples

For all examples, the following test methods were used:

thermal conductivity was measured using C-Therm TCi.

The mechanical properties (compressive modulus) were determined according to ASTM D1621.

The density was determined as the mass of the aerogel divided by the geometric volume of the aerogel.

Linear shrinkage was determined as the difference between the gel and aerogel diameters divided by the gel diameter.

The water absorbed by the aerogel sample was determined using the following equation:

example 1

Aerogels obtained by Using Cardolite NC-547 and Desmodur N3300

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 5 wt%. To prepare 30mL of sample, 0.58g of Cardolite NC-547 was dissolved in 23.11g of MIBK and then 0.64g of Desmodur N3300 was added. The mixture was stirred manually and 0.06g of DABCO was added. The solution was left at room temperature overnight.

The resulting gel was washed three times every 24 hours with acetone, using three gel volumes of solvent in each wash cycle. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 1 shows the measured characteristics of the aerogels obtained.

TABLE 1

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.069	22	35

Example 2

Aerogels obtained using Cardolite NC-514 and Desmodur N3900

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 10 wt%. To prepare 30mL of sample, 0.46g of Cardolite NC-514 was dissolved in 23.57g of MIBK and then 0.84g of Desmodur N3900 was added. The mixture was stirred manually and 0.124g of DABCO was added. The solution was left at room temperature overnight.

The resulting gel was washed three times every 24 hours with acetone, using three gel volumes of solvent for each wash cycle. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 2 shows the measured characteristics of the aerogels obtained.

TABLE 2

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.046	8	33

Example 3

Aerogels obtained Using Cardolite NC-514 and Desmodur N3200

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 10 wt%. To prepare 30mL of sample, 0.43g of Cardolite NC-514 was dissolved in 23.11g of MIBK and then 0.78g of Desmodur N3200 was added. The mixture was stirred manually and 0.122g of DABCO was added. The solution was left at room temperature overnight.

The resulting gel was washed three times every 24 hours with acetone, using three gel volumes of solvent for each wash cycle. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 3 shows the measured characteristics of the aerogels obtained.

TABLE 3

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.072	19	35

Example 4

Aerogels obtained using Erisys GE35 and Desmodur N3300

The isocyanate/epoxy equivalent ratio was 6:1, the total solids content was 6 wt% and the catalyst accounted for 10 wt%. To prepare 30mL of sample, 0.50g Erisys GE35 was dissolved in 22.93g MIBK and then 0.96g Desmodur N3300 was added. The mixture was stirred manually and 0.146g of DABCO was added. The solution was left at room temperature overnight.

The resulting gel was washed three times every 24 hours with acetone, using three gel volumes of solvent for each wash cycle. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 4 shows the measured characteristics of the aerogels obtained.

TABLE 4

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.060	11	34

Example 5

Aerogels obtained using tris (2, 3-epoxypropyl) isocyanurate and Desmodur44V

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 10 wt% and the catalyst was 10 wt%. To prepare a 30mL sample, 0.38g of tris (2, 3-epoxypropyl) isocyanurate was dissolved in 21.90g of acetone and then 2.05g of Desmodur44V was added. The mixture was stirred manually and 0.243g of DABCO was added. The solution was left at room temperature for 6 hours.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 5 shows the measured properties of the aerogels obtained.

TABLE 5

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.135	6	40

Example 6

Aerogels obtained using Erisys GE35 and Desmodur44V

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 15 wt% and the catalyst was 10 wt%. To prepare 30mL of sample, 2.03g of Erisys GE35 was dissolved in 21.08g of MIBK and then 1.69g of Desmodur44V was added. The mixture was stirred manually and 0.37g of DABCO was added. The solution was placed in an oven at 80 ℃ for 1 hour and 30 minutes.

The resulting gel was washed three times every 24 hours with acetone, using three gel volumes of solvent for each wash cycle. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 6 shows the measured characteristics of the aerogels obtained.

TABLE 6

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)	Compressive modulus (MPa)	Compressive strength (MPa)
					0.215	24.7	41	5.38	0.40

Example 7

Aerogels obtained using Erisys GE35 and Desmodur RE in DMAC

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 10 wt% and the catalyst was 10 wt%. To prepare 30mL of sample, two solutions were used. A first solution was prepared by dissolving 1.57g Erisys GE35 in 11.07g DMAc and then adding 4.72g Desmodur RE. A second solution was prepared by dissolving 0.284g of TBD in 11.07g of DMAc. The first and second solutions were mixed together and a gel was formed after 5 minutes.

The resulting gel was washed stepwise in a mixture of acetone 1:3DMAc, acetone 1:1DMAc, acetone 3:1DMAc and acetone, with each wash cycle performed over a 24 hour period and three gel volumes of solvent used for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 7 shows the measured characteristics of the aerogels obtained.

TABLE 7

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)	Compressive modulus (MPa)	Compressive strength (MPa)
					0.133	20	36	0.35	0.0035

Example 8

Aerogels obtained using CER 4221 and Desmodur44V

The isocyanate/epoxy equivalent ratio was 1:2, the total solids content was 12% by weight and the catalyst was 10%. To prepare 30mL of sample, 1.99g of CER 4221 was dissolved in 21.55g of acetone, followed by the addition of 0.96g of Desmodur 44V. The mixture was stirred manually and then 0.239g of DABCO was added. The solution was left at room temperature overnight.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 8 shows the measured characteristics of the aerogels obtained.

TABLE 8

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.052	4	35

Example 9

Aerogels obtained using Vikoflex 7170 and Desmodur RE in MEK

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 10 wt%. To prepare a 30mL sample, 0.31g Vikoflex 7170 was dissolved in 20.93g MEK, followed by the addition of 3.40g Desmodur RE. The mixture was stirred manually and then 0.29g of DABCO was added. The solution was left at room temperature for 1 hour.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 9 shows the measured characteristics of the aerogels obtained.

TABLE 9

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.066	13.6	31

Example 10

Aerogels obtained using Cardolite NC-514S and mixtures of the isocyanates Desmodur IL and Desmodur N3300

The aromatic isocyanate/aliphatic isocyanate/epoxy equivalent ratio was 1:3:1, the total solids content was 6 wt% and the catalyst accounted for 1.5 wt%. To prepare 30mL of sample, 0.44g of Cardolite NC-514S was dissolved in 22.70g of acetone, then 0.69g of Desmodur N3300 was added, and finally 0.62g of Desmodur IL was added. The mixture was stirred manually and then 0.02g of DABCO was added. The solution was left at room temperature for 3 hours.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 10 shows the measured characteristics of the aerogels obtained.

Watch 10

Density (g/cm)³)	LinearityShrinkage (%)	Thermal conductivity (mW/m. K)
			0.054	5.8	32

Example 11

Aerogels obtained using Epiclon HP-7200H and a mixture of Desmodur RE and Desmodur N3300 reinforced with glass wool and chopped strand glass mat (-30% by weight based on the weight of the aerogel).

The aromatic isocyanate/aliphatic isocyanate/epoxy equivalent ratio was 1:3:1, the total solids content was 6 wt% and the catalyst accounted for 10 wt%. To prepare 30mL of sample, 0.42g of Epiclon HP-7200H was dissolved in 23.03g of acetone, then 0.68g of Desmodur N3300 was added, and finally 0.88g of Desmodur RE was added. The mixture was stirred manually and then 0.15g of DABCO was added. Then, a glass chopped strand mat (0.22g) and glass wool (0.14g) were incorporated. The solution was left at ambient temperature for 1 hour.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 11 shows the measured characteristics of the obtained aerogels.

TABLE 11

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)	Compressive modulus (MPa)	Compressive strength (MPa)
					0.070	1.0	38	0.13	0.02

Example 12

Aerogels obtained using Epiclon HP-5000 and Desmodur RE

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 10 wt%. To prepare a 30mL sample, 0.42g of Epiclon HP-5000 was dissolved in 21.21g of MIBK, followed by the addition of 3.01g of Desmodur RE. The mixture was stirred manually and then 0.12g of DABCO was added. The solution was placed in an oven at 80 ℃ for 30 minutes.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 12 shows the measured characteristics of the obtained aerogels.

TABLE 12

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.054	1.58	35

Example 13

Aerogels obtained using Epiclon HP-9500 and Desmodur RE

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 15 wt% and the catalyst was 10 wt%. To prepare a 30mL sample, 1.25g of Epiclon HP-9500 was dissolved in 14.90g of MIBK, followed by the addition of 9.79g of Desmodur RE. The mixture was stirred manually and then 0.39g of DABCO was added. The solution was placed in an oven at 80 ℃ for 30 minutes.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 13 shows the measured characteristics of the obtained aerogels.

Watch 13

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)	Compressive modulus (MPa)	Compressive strength (MPa)
					0.168	4.47	45	1.06	0.11

Example 14

Aerogels obtained using Erisys GE35 and Desmodur44V reinforced with glass wool and glass chopped strand mat (-30% by weight based on aerogel weight).

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 10%. To prepare a 30mL sample, 0.64g Erisys GE35 was dissolved in 23.09g MIBK, followed by the addition of 0.57g Desmodur 44V. The mixture was stirred manually and then 0.12g of DABCO was added. Then, a glass chopped strand mat (0.23g) and glass wool (0.15g) were incorporated. The solution was placed in an oven at 80 ℃ for 1 hour and 30 minutes.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 14 shows the measured characteristics of the obtained aerogels.

TABLE 14

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)	Compressive modulus (MPa)	Compressive strength (MPa)
					0.057	1.91	33	0.016	0.001

Example 15

Aerogels obtained using Erisys GE35 and Desmodur44V reinforced with a honeycomb structure based on aramid fibers and phenolic resins.

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 5 wt% and the catalyst was 10%. To prepare a 30mL sample, 0.64g Erisys GE35 was dissolved in 23.09g MIBK, followed by the addition of 0.57g Desmodur 44V. The mixture was stirred manually and then 0.12g of DABCO was added. Then, a honeycomb structure (cell size 3.2mm and density 48 kg/m) was incorporated³) And the solution was placed in an oven at 80 ℃ for 1 hour and 30 minutes.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel.

Watch 15

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)	Compressive modulus (MPa)	Compressive strength (MPa)
					0.092	4.42	37	48.7	2.93

Example 16

Aerogels obtained using KR-516 and Desmodur N3300.

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 6 wt% and the catalyst was 10 wt%. To prepare a 30mL sample, 0.16g KR-516 was dissolved in 5.9g DMAc mixed with 17.71g acetone as a solvent, followed by addition of 1.34g Desmodur N3300. The mixture was stirred manually and then 0.15g of DABCO was added. The solution was left to gel at room temperature.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 16 shows the measured characteristics of the obtained aerogels.

TABLE 16

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.059	8.95	35

Example 17

Aerogels obtained using X-12-981S and Desmodur N3300.

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 6 wt% and the catalyst was 10 wt%. To prepare 30mL of a sample, 0.13g X-12-981S was dissolved in 5.9g DMAc mixed with 17.71g acetone as a solvent, followed by the addition of 1.38g Desmodur N3300. The mixture was stirred manually and then 0.15g of DABCO was added. The solution was left to gel at room temperature.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 17 shows the measured characteristics of the obtained aerogels.

TABLE 17

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.066	11.84	35

Example 18

Aerogels obtained using KR-470 and Desmodur N3300.

The isocyanate/epoxy equivalent ratio was 4:1, the total solids content was 8 wt% and the catalyst accounted for 20 wt%. To prepare a 30mL sample, 0.08g KR-470 was dissolved in 11.98g DMAc mixed with 11.98g acetone as a solvent, followed by addition of 2.0g Desmodur N3300. The mixture was stirred manually and then 0.42g of DMBA was added. The solution was left to gel at room temperature.

The resulting gel was washed three times with acetone every 24 hours, using three gel volumes of solvent for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Table 18 shows the measured characteristics of the obtained aerogels.

Watch 18

Density (g/cm)³)	Linear shrinkage (%)	Thermal conductivity (mW/m. K)
			0.110	17.37	35

Example 19

Comparison between aerogels obtained using hydrophilic and hydrophobic resins.

All samples were prepared under the same conditions but using different resins. The epoxy resin used was ErisysGE35 (hydrophobic), Epiclon 7200 (hydrophobic), 1, 6-hexanediol diglycidyl ether (hydrophilic), polyethylene glycol diglycidyl ether (hydrophilic). The isocyanate used was Desmodur RE, the isocyanate/epoxy equivalent ratio was 4:1, the solids content was 10 wt% and DABCO as catalyst accounted for 10 phr. The amounts of the different ingredients are summarized in table 19. The monomers were dissolved in MIBK and then the catalyst was added. The resulting solution was placed in an oven at 80 ℃ for 1 hour. The resulting gel was washed three times with acetone every 24 hours, using an amount of solvent of three gel volumes for each step. Subsequently, by CO₂Supercritical drying (SCD) to dry the gel. Of the aerogels obtainedThe properties are summarized in table 20 and table 21.

TABLE 19 formulation of samples prepared with different epoxy resins and the same conditions

Table 20 results obtained for samples prepared with different epoxy resins.

Table 21 water absorption test results for samples prepared with different epoxy resins.

Claims

1. A hydrophobic organic aerogel obtained by reacting an isocyanate compound having a functionality of 2 to 6 with an epoxy compound having a functionality of 2 to 6 in the presence of a solvent, wherein the isocyanate compound is selected from the group consisting of:

wherein a is an integer from 1 to 30;

wherein b is an integer from 1 to 30;

wherein c is an integer from 1 to 30;

And

d is an integer of 0 to 3;

and mixtures thereof;

and wherein the epoxy compound is selected from:

wherein e¹、e²、e³The same or different and independently selected from 1 to 12; f. of¹、f²、f³The same or different and independently selected from 1 to 12; g¹、g²、g³The same or different and independently selected from 1 to 26; h is¹、h²、h³Are the same or different and are independently selected from 0 toWith the proviso that h¹+h²+h³At least 2; i.e. i¹、i²、i³The same or different and independently selected from 0 to 25; j is a function of¹、j²、j³The same or different and independently selected from 1 to 26; k is a radical of¹、k²、k³Are the same or different and are independently selected from 0 to 6, provided that k is¹+k²+k³At least 2; and l¹、l²、l³The same or different and independently selected from 0 to 25;

wherein p is an integer from 1 to 5;

and mixtures thereof.

2. The hydrophobic organic aerogel of claim 1, wherein the isocyanate compound is reacted with the epoxy compound in the presence of a catalyst.

3. Hydrophobic organic aerogel according to claim 1 or 2, wherein the isocyanate compound is selected from the group consisting of 3,5-bis (6-isocyanatohexyl) -6- (6-isocyanatohexylimino) -1,3, 5-oxadiazine-2, 4-dione, 1,3-bis [ p- ({ p- [3,5-bis (3-isocyanatotolyl) -2,4,6-trioxo-1,3, 5-triazacyclohexan-1-yl ] phenyl } methyl) phenyl ] -5- (3-isocyanatotolyl) -1,3, 5-triazacyclohexan-2, 4,6-trione, 4' -diphenylmethane diisocyanate, 1,3, 5-tris (6-isocyanatohexyl) -1,3, 5-triazacyclohexane-2, 4,6-trione, 1,3-bis (6-isocyanatohexyl) -1- (6-isocyanatohexylcarbamoyl) urea, 6- [3- (6-isocyanatohexyl) -2, 4-dioxo-1, 3-diazetidin-1-yl ] hexyl N- (6-isocyanatohexyl) carbamate, 1- [ bis (4-isocyanatophenyl) methyl ] -4-isocyanatobenzene and mixtures thereof.

4. Hydrophobic organic aerogel according to any of claims 1 to 3, wherein the epoxy compound is selected from the group consisting of 2- [ (3- { [ 2-hydroxy-3- ({2- [ (2-epoxyethyl) methoxy ] -4-pentadecylphenyl } methyl) -4-pentadecylphenyl ] methyl } -2- [ (2-epoxyethyl) methoxy ] -4-pentadecylphenyl) methyl ] -6- ({2- [ (2-epoxyethyl) methoxy ] -6-pentadecylphenyl } methyl) -3-pentadecylphenol, 2, 3-bis { (E) -11- [ (2-epoxyethyl) methoxy ] -8-heptadecenylcarbonyloxy } propyl (E) -12- [ (2-epoxyethyl) methyl Oxy ] -9-octadecenoic acid ester, 2- { [ m- (8- { p- [ (2-epoxyethyl) methoxy ] phenyl } pentadecyl) phenoxy ] methyl } oxirane, tris (2, 3-epoxypropyl) isocyanurate, 2, 3-bis (2- {3- [2- (3-propyl-2-epoxyethyl) ethyl ] -2-epoxyethyl } propionyloxy) propyl 3- {3- [2- (3-propyl-2-epoxyethyl) ethyl ] -2-epoxyethyl } propanoate, polymer with 2- ({3- [ (3-methoxy-1-naphthyl) methyl ] tolyloxy } methyl) oxirane, 7-oxabicyclo [4.1.0] hept-3-ylmethyl 7-oxabicyclo [4.1.0] Heptane-3-carboxylic acid ester, phenol polymer with 3a,4,7,7 a-tetrahydro-4, 7-methylene-1H-indene glycidyl ether and mixtures thereof.

5. Hydrophobic organic aerogel according to any of claims 1 to 4, wherein the ratio of epoxy groups to isocyanate groups is from 1:15 to 5:1, preferably from 1:8 to 3:1, and more preferably from 1:6 to 2: 1.

6. The hydrophobic organic aerogel according to any of claims 1 to 5, wherein the solvent is a polar solvent, preferably a polar aprotic solvent selected from the group consisting of dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), Dimethylsulfoxide (DMSO), acetonitrile, acetone, Methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK) and mixtures thereof.

7. The hydrophobic organic aerogel according to any of claims 2 to 6, wherein the catalyst is selected from alkylamines, aromatic amines, imidazole derivatives, aza compounds, guanidine derivatives and amidines, preferably selected from triethylamine, trimethylamine, N-dimethylbenzylamine, 1, 4-diazabicyclo [2.2.2] octane, 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU), 1,5, 7-triazabicyclo [4.4.0] dec-5-ene (TBD), dibutyltin dilaurate and mixtures thereof.

8. The hydrophobic organic aerogel according to any of claims 1 to 7, wherein the aerogel further comprises at least one reinforcing material, wherein the reinforcing material is selected from the group consisting of fibers, particles, fibrous fabrics and mats, 3D structures, and mixtures thereof.

9. Hydrophobic organic aerogel according to any of claims 1 to 8, wherein the hydrophobic organic aerogel has a solids content of 4 to 40%, preferably 5 to 30%, based on the initial solids content of the solution.

10. The hydrophobic organic aerogel of any of claims 1-9, wherein the hydrophobic organic aerogel has a thermal conductivity of less than 60 mW/m-K, preferably less than 55 mW/m-K, more preferably less than 50 mW/m-K, and even more preferably less than 45 mW/m-K.

11. Method for the preparation of hydrophobic organic aerogels according to any of claims 1 to 10, comprising the steps of:

2) adding catalyst, if present, and mixing;

3) allowing the mixture to stand to form a gel;

4) washing the gel with a solvent; and

5) the gel is dried by supercritical or ambient drying.

12. The method according to claim 11, wherein in step 3a temperature from room temperature to 160 ℃ is applied to form a gel, preferably a temperature from room temperature to 80 ℃.

13. Thermal or acoustic insulation material comprising the hydrophobic organic aerogel according to any of claims 1 to 10.

14. Use of the hydrophobic organic aerogel according to any of claims 1 to 10 as thermal or acoustic insulation material.

15. Use of the hydrophobic organic aerogel according to claim 14, wherein the hydrophobic organic aerogel is used as a thermal insulation material for coolant storage.