CN117107552A - Atmospheric pressure drying anisotropic silicon-based aerogel composite fiber paper and preparation method thereof - Google Patents
Atmospheric pressure drying anisotropic silicon-based aerogel composite fiber paper and preparation method thereof Download PDFInfo
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- CN117107552A CN117107552A CN202310827388.1A CN202310827388A CN117107552A CN 117107552 A CN117107552 A CN 117107552A CN 202310827388 A CN202310827388 A CN 202310827388A CN 117107552 A CN117107552 A CN 117107552A
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- fiber paper
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- aluminum silicate
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- 239000000835 fiber Substances 0.000 title claims abstract description 123
- 239000004964 aerogel Substances 0.000 title claims abstract description 82
- 239000002131 composite material Substances 0.000 title claims abstract description 52
- 238000001035 drying Methods 0.000 title claims abstract description 31
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title claims abstract description 25
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 25
- 239000010703 silicon Substances 0.000 title claims abstract description 25
- 239000002904 solvent Substances 0.000 claims abstract description 67
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical compound [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 claims abstract description 61
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims abstract description 53
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 53
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 50
- 239000007822 coupling agent Substances 0.000 claims abstract description 49
- 239000003960 organic solvent Substances 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 28
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 22
- 230000032683 aging Effects 0.000 claims abstract description 22
- 230000006837 decompression Effects 0.000 claims abstract description 8
- 238000009736 wetting Methods 0.000 claims abstract description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 18
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 12
- 238000011065 in-situ storage Methods 0.000 claims description 11
- 239000000126 substance Substances 0.000 claims description 10
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 claims description 8
- 229920001296 polysiloxane Polymers 0.000 claims description 8
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 6
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 6
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 claims description 6
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 claims description 6
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 6
- 239000000741 silica gel Substances 0.000 claims description 5
- 229910002027 silica gel Inorganic materials 0.000 claims description 5
- AMQJEAYHLZJPGS-UHFFFAOYSA-N N-Pentanol Chemical compound CCCCCO AMQJEAYHLZJPGS-UHFFFAOYSA-N 0.000 claims description 4
- VGWJKDPTLUDSJT-UHFFFAOYSA-N diethyl dimethyl silicate Chemical compound CCO[Si](OC)(OC)OCC VGWJKDPTLUDSJT-UHFFFAOYSA-N 0.000 claims description 3
- POPACFLNWGUDSR-UHFFFAOYSA-N methoxy(trimethyl)silane Chemical compound CO[Si](C)(C)C POPACFLNWGUDSR-UHFFFAOYSA-N 0.000 claims description 3
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 claims description 3
- JCVQKRGIASEUKR-UHFFFAOYSA-N triethoxy(phenyl)silane Chemical compound CCO[Si](OCC)(OCC)C1=CC=CC=C1 JCVQKRGIASEUKR-UHFFFAOYSA-N 0.000 claims description 3
- 238000012546 transfer Methods 0.000 abstract description 7
- 238000004132 cross linking Methods 0.000 abstract description 5
- 230000007547 defect Effects 0.000 abstract description 4
- 239000003779 heat-resistant material Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 17
- 239000000463 material Substances 0.000 description 9
- 239000000047 product Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 4
- 238000009413 insulation Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000004965 Silica aerogel Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000000877 morphologic effect Effects 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000006087 Silane Coupling Agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000000499 gel Substances 0.000 description 1
- 239000012784 inorganic fiber Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
- D21H27/18—Paper- or board-based structures for surface covering
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
- D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
- D21H23/22—Addition to the formed paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
- D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
- D21H23/22—Addition to the formed paper
- D21H23/46—Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
- D21H25/04—Physical treatment, e.g. heating, irradiating
- D21H25/06—Physical treatment, e.g. heating, irradiating of impregnated or coated paper
Landscapes
- Silicon Compounds (AREA)
Abstract
The invention provides a preparation method of normal-pressure drying anisotropic silicon-based aerogel composite fiber paper, and belongs to the technical field of heat-resistant materials. The preparation method of the composite fiber paper comprises the following steps: preparing at least two hydrophobic siloxane coupling agent solvents with different concentrations; preparing a hydrophobic siloxane coupling agent solvent with the minimum concentration, tetraethoxysilane and a first organic solvent to obtain aerogel silica sol; taking the rest hydrophobic siloxane coupling agent solvent as a gradient solvent; paving aluminum silicate fiber paper, and adding a first organic solvent to the upper surface of the aluminum silicate fiber paper for wetting; adding aerogel silica sol on the upper surface, and sequentially adding gradient solvents from small to large according to the concentration in a reduced pressure state to form a siloxane layer; and (5) performing aging drying and standing treatment to obtain the composite fiber paper. The invention reduces the crosslinking degree of the aerogel, improves the flexibility, simultaneously changes the concentration gradient, prepares the anisotropic aerogel by matching with a decompression method, can ensure the heat-resistant temperature of the fiber paper, and also avoids the defect of reducing the heat transfer efficiency.
Description
Technical Field
The invention belongs to the technical field of heat-resistant materials, and particularly relates to normal-pressure drying anisotropic silicon-based aerogel composite fiber paper and a preparation method thereof.
Background
The aluminum silicate fiber paper is a special inorganic fiber material, consists of aluminum silicate fibers, a high-temperature binder and an additive, and has excellent heat insulation performance and chemical stability. The aluminum silicate fiber paper is mainly used as a heat insulation and fire protection material for high temperature equipment. Advantages of aluminum silicate fiber paper include: high temperature stability, light weight, low density, good flexibility and excellent thermal insulation properties. In short, aluminum silicate fiber paper is an excellent high-temperature heat insulation material and is widely applied to high-temperature equipment in the industries of steel, petrochemical industry, electric power and the like.
In the ceramic preparation process, aluminum silicate fiber paper is used as a consumable material in a huge amount. However, after baking at high temperature, the mechanical properties of the aluminum silicate fiber paper are reduced, so that the aluminum silicate fiber paper cannot be reused.
In the traditional method, the silicon dioxide aerogel and the aluminum silicate fiber paper are compounded, and although the heat-resistant stability of the material can be enhanced to a certain extent, the brittleness of the fiber paper after baking can be increased due to the characteristic of larger brittleness of the aerogel and simple compounding treatment; meanwhile, the introduction of aerogel has the problem of obstructing heat transfer, so that the integral firing process of ceramic products can be greatly influenced.
In summary, the existing conventional treatment method has the defects that the brittleness of the finished composite fiber paper is increased, heat transfer is blocked, and the firing process of the ceramic product is further affected, so that inconvenience is caused to the preparation of the ceramic product.
Disclosure of Invention
In order to solve the problems, the invention provides a preparation method of normal-pressure drying anisotropic silicon-based aerogel composite fiber paper, which comprises the following steps:
s1, preparing at least two hydrophobic siloxane coupling agent solvents with different concentrations; preparing a hydrophobic siloxane coupling agent solvent with the minimum relative concentration, ethyl orthosilicate and a first organic solvent to obtain aerogel silica sol; and taking the rest concentration of the hydrophobic siloxane coupling agent solvent as a gradient solvent;
s2, laying aluminum silicate fiber paper, and adding the first organic solvent to the upper surface of the aluminum silicate fiber paper for wetting;
s3, adding the aerogel silica sol to the upper surface of the wetted aluminum silicate fiber paper under the condition of normal temperature and normal pressure, so that the aerogel silica sol grows in situ on the surface of the aluminum silicate fiber paper to form a silica sol layer;
s4, sequentially adding the gradient solvents on the silica sol layer from small to large according to the concentration under the condition of decompression to form siloxane layers with different concentrations;
and S5, performing aging and drying treatment and standing treatment to obtain the composite fiber paper.
Preferably, in the step of forming the siloxane layers with different concentrations by sequentially adding the gradient solvents from small to large on the silica gel layer based on the reduced pressure state, the pressure condition in the reduced pressure state is not more than 0.098Mpa.
Preferably, the hydrophobic siloxane coupling agent solvents of different concentrations are formulated based on the amount of the substance of the ethyl orthosilicate;
preferably, the ratio of the amounts of the ethyl orthosilicate and the hydrophobic silicone coupling agent substance ranges from 1 (0.1-1.0).
Preferably, the aerogel silica sol is prepared from the tetraethoxysilane, the hydrophobic siloxane coupling agent and the first organic solvent according to the mass ratio of 1 (0.1-1.0) to 10-50.
Preferably, the hydrophobic siloxane coupling agent is any one or more of methyltrimethoxysilane, methyltriethoxysilane, dimethoxydiethoxysilane, phenyltriethoxysilane and trimethylmethoxysilane.
Preferably, the first organic solvent is any one or more of methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, sec-butanol, amyl alcohol and isomers thereof, hexanol and isomers thereof, and acetone.
Preferably, the step of adding the aerogel silica sol to the upper surface of the wetted aluminum silicate fiber paper under the condition of normal temperature and normal pressure to enable the aerogel silica sol to grow on the surface of the aluminum silicate fiber paper in situ further comprises the step of standing;
preferably, the rest time is 0.5 hours to 3.0 hours.
Preferably, the step S4 is based on that the gradient solvents are sequentially added on the silica gel layer from small to large according to the concentration under the reduced pressure state, after the siloxane layers with different concentrations are formed, the hydrophobic siloxane coupling agent solvent with the next concentration is added after a preset interval time is separated;
preferably, the preset interval time is 0.5 hours to 1.0 hours.
Preferably, the aging drying treatment is:
taking a second organic solvent as an aging liquid, and aging and drying under normal pressure;
preferably, the aging drying treatment is carried out for 12 hours to 60 hours;
preferably, the normal pressure state of the aging drying treatment is one atmospheric pressure state;
preferably, the second organic solvent is one or more of methanol, ethanol, propanol and acetone.
Preferably, the standing time of the standing treatment is 6 hours to 60 hours.
Preferably, the length of the aluminum silicate fiber paper is 1cm-50cm, the width of the aluminum silicate fiber paper is 1cm-10cm, and the thickness of the aluminum silicate fiber paper is 1mm-4mm.
In addition, in order to solve the problems, the invention also provides composite fiber paper, which is prepared by the preparation method of the normal-pressure drying anisotropic silicon-based aerogel composite fiber paper.
The invention provides normal-pressure drying anisotropic silicon-based aerogel composite fiber paper and a preparation method thereof. Wherein the preparation method comprises the following steps: preparing at least two hydrophobic siloxane coupling agent solvents with different concentrations; preparing a hydrophobic siloxane coupling agent solvent with the minimum concentration, tetraethoxysilane and a first organic solvent to obtain aerogel silica sol; taking the rest hydrophobic siloxane coupling agent solvent as a gradient solvent; paving aluminum silicate fiber paper, and adding a first organic solvent to the upper surface of the aluminum silicate fiber paper for wetting; adding aerogel silica sol on the upper surface, and sequentially adding gradient solvents from small to large according to the concentration in a reduced pressure state to form a siloxane layer; and (5) performing aging drying and standing treatment to obtain the composite fiber paper. According to the invention, on the basis of aluminum silicate fiber paper, the in-situ growth is utilized to obtain the porous elastic interconnection network and the firm and flexible composite structure, and due to the addition of the hydrophobic siloxane coupling agent, the crosslinking degree of the aerogel is reduced, so that the flexibility is improved, meanwhile, the concentration gradient is changed, and the anisotropic aerogel is prepared by matching with a decompression method, so that the heat-resistant temperature of the fiber paper can be ensured, and the defect of reducing the heat transfer efficiency is avoided.
Drawings
FIG. 1 is a microscopic morphological electron microscope image of aluminum silicate fiber paper in example 1 of the method for preparing an anisotropic silicon-based aerogel composite fiber paper dried under normal pressure according to the present invention;
FIG. 2 is a microscopic morphological electron microscope image of the composite fiber paper prepared in example 1 of the method for preparing the anisotropic silicon-based aerogel composite fiber paper according to the present invention;
FIG. 3 is a microscopic morphological electron microscope image of the composite fiber paper prepared in comparative example 2 of the method for preparing the normal pressure dry anisotropic silica aerogel composite fiber paper according to the present invention;
FIG. 4 is a graph showing the comparison of the dimensional shrinkage of the highest stability points and the highest stability points of examples and comparative examples in a lateral comparison test of the method for preparing an anisotropic silicon-based aerogel composite fiber paper according to the present invention;
fig. 5 is a graph showing the relationship between the variation of thermal conductivity coefficient at 300 ℃ and the number of different concentration gradient formulations of aerogel silica sol in the transverse comparison test experiments of the preparation method of the normal pressure drying anisotropic silica aerogel composite fiber paper.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Unless defined otherwise hereinafter, all technical and scientific terms used in the detailed description of the invention are intended to be identical to what is commonly understood by one of ordinary skill in the art. While the following terms are believed to be well understood by those skilled in the art, the following definitions are set forth to better explain the present invention.
As used herein, the terms "comprising," "including," "having," "containing," or "involving" are inclusive or open-ended and do not exclude additional unrecited elements or method steps. The term "consisting of …" is considered to be a preferred embodiment of the term "comprising". If a certain group is defined below to contain at least a certain number of embodiments, this should also be understood to disclose a group that preferably consists of only these embodiments.
The indefinite or definite article "a" or "an" when used in reference to a singular noun includes a plural of that noun.
The term "about" in the present invention means a range of accuracy that one skilled in the art can understand while still guaranteeing the technical effect of the features in question. The term generally means a deviation of + -10%, preferably + -5%, from the indicated value.
Furthermore, the terms first, second, third, (a), (b), (c), and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.
Unless defined otherwise or clearly indicated by context, all technical and scientific terms in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
The technical solution of the present invention is further described in detail below with reference to specific embodiments, but the present invention is not limited thereto, and any modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.
The invention provides a preparation method of normal-pressure drying anisotropic silicon-based aerogel composite fiber paper, which comprises the following steps:
s1, preparing at least two hydrophobic siloxane coupling agent solvents with different concentrations; preparing a hydrophobic siloxane coupling agent solvent with the minimum relative concentration, ethyl orthosilicate and a first organic solvent to obtain aerogel silica sol; and taking the rest concentration of the hydrophobic siloxane coupling agent solvent as a gradient solvent;
s2, laying aluminum silicate fiber paper, and adding the first organic solvent to the upper surface of the aluminum silicate fiber paper for wetting;
s3, adding the aerogel silica sol to the upper surface of the wetted aluminum silicate fiber paper under the condition of normal temperature and normal pressure, so that the aerogel silica sol grows in situ on the surface of the aluminum silicate fiber paper to form a silica sol layer;
s4, sequentially adding the gradient solvents on the silica sol layer from small to large according to the concentration under the condition of decompression to form siloxane layers with different concentrations;
and S5, performing aging and drying treatment and standing treatment to obtain the composite fiber paper.
In step S1, at least two hydrophobic silicone coupling agent solvents with different concentrations need to be prepared, and the solvents can be divided into two parts according to the concentrations:
(1) A first part: for the hydrophobic siloxane coupling agent solvent with the minimum concentration, the hydrophobic siloxane coupling agent solvent needs to be further formulated, specifically, the part (the hydrophobic siloxane coupling agent solvent with the minimum concentration) is formulated with tetraethoxysilane and a first organic solvent to obtain aerogel silica sol;
(2) A second part: the remaining other concentration of hydrophobic silicone coupling agent solvent, in an amount of one or more, acts as a gradient solvent.
For example, S1 may be the following specific implementation steps:
(1) The first step, preparing at least 4 hydrophobic siloxane coupling agent solvents with different concentrations; a, B, C, D are respectively arranged in sequence from small to large according to the concentration;
(2) Step two, taking a hydrophobic siloxane coupling agent solvent A with the minimum concentration, and preparing the hydrophobic siloxane coupling agent solvent A with tetraethoxysilane and a first organic solvent to obtain aerogel silica sol;
(3) Thirdly, the remaining other concentrations of hydrophobic siloxane coupling agent solvents, B, C and D,3 different concentrations of hydrophobic siloxane coupling agent solvents, were used as gradient solvents.
The second step and the third step may be performed either before or simultaneously.
The specific examples are shown in the following table:
table 1, comparison table of the aerogel silica sol and gradient solvent composition pre-formulated in step S1
In the step S2, after the aluminum silicate fiber paper is laid, the first organic solvent is added to the upper surface of the aluminum silicate fiber paper to wet the paper.
Specifically, in the normal pressure state, a filter, a funnel device and the like, for example, a sand core filter can be adopted, wherein a suction filtration bottle is placed below the sand core filter, a vacuum pump is connected, a sand core funnel is placed at the upper end of the sand core filter, aluminum silicate fiber paper is paved at the sand core position, and in the normal pressure state, a small amount of first organic solvent is added from the upper surface of the aluminum silicate fiber paper, so that the first organic solvent gradually permeates, and the first organic solvent is wetted.
The aluminum silicate fiber paper is placed on a filter device and wetted with a small amount of solvent. This is done to form a uniform thin layer on the surface of the fibrous paper so that the aerogel silica sol in the subsequent step can be better bonded thereto.
In the step S3, the aerogel silica sol is added to the upper surface of the wetted aluminum silicate fiber paper under the normal pressure state, so that the aerogel silica sol grows in situ on the surface of the aluminum silicate fiber paper to form a silica sol layer;
in the step S3, the pressure condition is a normal pressure state, and the prepared aerogel silica sol is added to the upper surface of the wetted aluminum silicate fiber paper, so that the aerogel silica sol grows on the fiber surface of the upper surface of the aluminum silicate fiber paper in situ.
The prepared aerogel silica sol is slowly introduced into a filtering device, and grows in situ on the surface of the bottom fiber of the aluminum silicate fiber paper. This means that the aerogel silica sol is accurately positioned to the surface of the fibrous paper, rather than into its interior or other areas. During this process, the silica sol gradually gels on the surface of the fibrous paper and forms a three-dimensional network structure, thereby fixing the fibrous paper together and enhancing its mechanical properties.
Wherein, the chemical reaction can be as follows:
(1)Si(OEt) 4 +2H 2 O→Si(OH) 4 +4EtOH；
(2)Si(OH) 4 →SiO 2 +2H 2 O。
in step S4, a gradient solvent is introduced onto the alumina silicate fiber paper in the filtration device under reduced pressure so that it forms a multi-layered hydrophobic siloxane film after a moment of reaction on the silica sol surface. Such treatment can improve the hydrophobicity and water resistance of the composite fiber paper. Wherein, the gradient solvent is added sequentially from small to large according to the concentration of the gradient solvent.
In summary, this method utilizes the combination of aerogel silica sol and aluminum silicate fiber paper to prepare composite fiber paper, and can further improve its performance by controlling the introduction of gradient solvents with different concentration gradients.
And (4) sequentially adding the gradient solvents according to the concentration from small to large on the silica gel layer under the pressure reducing state to form the siloxane layers with different concentrations, wherein the pressure condition under the pressure reducing state is not more than 0.098Mpa.
In the step S4, the pressure condition under the reduced pressure state is not more than 0.098Mpa, namely, the pressure is more than 0Mpa and less than or equal to 0.098Mpa.
It should be noted that the definition of the pressure condition is closely related to the key factors of forming the anisotropic silica aerogel composite fiber paper. The depressurization is accomplished by reducing the pressure within the system, which causes dissolved substances in the gas or liquid to be released to form bubbles or holes. In preparing anisotropic aerogel composite fiber paper, the depressurization process is very important because it can control the structure and morphology of the aerogel.
By defining the pressure condition in the depressurized state to be not more than 0.098MPa in step S4, an appropriate depressurization effect can be ensured. The principle is as follows:
(1) Control the pore structure of the aerogel: a certain pressure may cause more gas or liquid to be released from the fibrous paper, forming more holes. Thus, more pore structures can be obtained, the specific surface area and the porosity of the aerogel are improved, and the adsorption capacity and the heat insulation performance of the aerogel are further enhanced.
(2) Ensure the heat resistance of the fiber paper: the certain pressure can reduce the crosslinking degree of the aerogel in the fiber paper, and maintain the flexibility and elasticity of the fiber paper, so that the heat resistance of the fiber paper is improved. Excessive pressure may cause excessive crosslinking of the aerogel, rendering the fibrous paper brittle, and reducing its heat resistance.
Based on the above principle, defining the pressure condition in the reduced pressure state to be not more than 0.098MPa can ensure the formation of anisotropic silica-based aerogel composite fiber paper having a suitable pore structure and excellent heat resistance.
Further, the hydrophobic siloxane coupling agent solvents with different concentrations are prepared according to the amount of the substance of the ethyl orthosilicate.
Further, the ratio of the amounts of the ethyl orthosilicate and the hydrophobic silicone coupling agent substance ranges from 1 (0.1-1.0). For example, it may be 1:0.1, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1.0, etc.
Further, the aerogel silica sol is prepared from the tetraethoxysilane, the hydrophobic siloxane coupling agent and the first organic solvent according to the mass ratio of 1 (0.1-1.0) to 10-50.
Further, the hydrophobic siloxane coupling agent is any one or more of methyltrimethoxysilane, methyltriethoxysilane, dimethoxydiethoxysilane, phenyltriethoxysilane and trimethylmethoxysilane.
Further, the first organic solvent is any one or more of methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, sec-butanol, amyl alcohol and isomers thereof, hexanol and isomers thereof, and acetone.
Further, the step of adding the aerogel silica sol to the upper surface of the wetted aluminum silicate fiber paper under the condition of normal temperature and normal pressure to enable the aerogel silica sol to grow on the surface of the aluminum silicate fiber paper in situ, and the step of standing is further included;
wherein, the standing time can be 0.5 hours to 3.0 hours. For example, it may be 0.5 hours, 1.0 hours, 1.5 hours, 2.0 hours, 2.5 hours, 3.5 hours, etc.
And (4) sequentially adding the gradient solvents to the silica gel layer according to the concentration from small to large in a decompression state, forming siloxane layers with different concentrations, and adding the hydrophobic siloxane coupling agent solvent with the next concentration after a preset interval time.
Further, the preset interval time is 0.5 hours to 1.0 hours. For example, it may be 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1.0 hours, etc.
Further, the aging and drying treatment is as follows:
taking a second organic solvent as an aging liquid, and aging and drying under normal pressure;
further, the aging and drying treatment time is 12 hours to 60 hours; for example, the time period may be 12 hours, 16 hours, 20 hours, 24 hours, 30 hours, 36 hours, 40 hours, 48 hours, 60 hours, or the like.
Further, the normal pressure state of the aging drying treatment is an atmospheric pressure state;
as described above, one atmosphere may be 1013.25Kpa.
Further, the second organic solvent is one or more of methanol, ethanol, propanol and acetone.
Further, the standing time of the standing treatment is 6 hours to 60 hours. For example, the time period may be 6 hours, 10 hours, 16 hours, 20 hours, 24 hours, 30 hours, 36 hours, 40 hours, 48 hours, 60 hours, or the like.
Further, the length of the aluminum silicate fiber paper is 1cm-50cm, the width of the aluminum silicate fiber paper is 1cm-10cm, and the thickness of the aluminum silicate fiber paper is 1mm-4mm. For example, the length of the aluminum silicate fiber paper can be 1cm, 5cm, 10cm, 15cm, 20cm, 25cm, 30cm, 35cm, 40cm, 45cm, 50cm, 55cm, 60cm, etc.; the width of the aluminum silicate fiber paper can be 1cm, 2cm, 4cm, 6cm, 8cm, 10cm and the like; the thickness of the aluminum silicate fiber paper can be 1mm, 2mm, 3mm, 4mm and the like.
In addition, the invention also provides composite fiber paper which is prepared by the preparation method of the normal-pressure drying anisotropic silicon-based aerogel composite fiber paper.
The invention is further illustrated by the following specific examples, but it should be understood that these examples are for the purpose of illustration only and are not to be construed as limiting the invention in any way.
Example 1
The preparation of the composite fiber paper is carried out by the following method:
step 1, taking aluminum silicate fiber paper with the length of 50cm, the width of 10cm and the thickness of 3mm, referring to an electron microscope image of the aluminum silicate fiber paper shown in FIG. 1, placing the aluminum silicate fiber paper into a sand core filter, and wetting the aluminum silicate fiber paper with a small amount of first organic solvent;
step 2, according to the proportion range of the amount of the hydrophobic siloxane coupling agent and the tetraethoxysilane (0.1-1.0): 1, 4 concentrations are configured, and the concentrations are respectively:
(1) Concentration 1:0.1:1;
(2) Concentration 2:0.3:1;
(3) Concentration 3:0.6:1;
(4) Concentration 4:1:1.
Wherein the concentration of the amount of the substance of the ethyl orthosilicate is 6mol/mL; accordingly, the concentration of the amount of the substance of the hydrophobic siloxane coupling agent solvent (methyltrimethoxysilane) is respectively: 0.6mol/mL (concentration 1), 1.8mol/mL (concentration 2), 3.6mol/mL (concentration 3) and 6mol/mL (concentration 4).
1mL of 0.6mol/mL methyltrimethoxysilane solvent (with the concentration of 1 being the minimum), 1mL of 6mol/mL tetraethoxysilane molar concentration and 20mol of first organic solvent (methanol) are taken and mixed to prepare a silicon mixed solution, and the silicon mixed solution is stirred for 30 minutes, and after the silicon mixed solution is hydrolyzed, aerogel silica sol is obtained.
The remaining 3 concentrations of hydrophobic siloxane coupling agent solvents, such as 1.8mol/mL, 3.6mol/mL, and 6mol/mL, were used as gradient solvents.
Step 3, maintaining a decompression state by using a vacuum pump, controlling the pressure within the range of 0MPa < P less than or equal to 0.098MPa, and sequentially introducing gradient solvents (residual hydrophobic siloxane coupling agents with different concentration gradients) into a filter according to the concentration from low to high; specifically, 0.24mL of 1.8mol/mL methyltrimethoxysilane solvent, 0.05mL of 3.6mol/mL methyltrimethoxysilane solvent, and 0.01mL of 6mol/mL methyltrimethoxysilane solvent were sequentially used, and the preset interval time between each concentration was 30 minutes.
And 4, standing for 1.0 hour, taking out the product after the product is basically shaped, flatly placing the product in a culture dish, adopting a proper volatile organic solvent as an aging liquid, aging and drying for 48 hours under normal pressure, and finally obtaining the anisotropic composite fiber paper, wherein the anisotropic composite fiber paper is an electron microscope image of the composite fiber paper with reference to FIG. 2.
Example 2
The preparation method used in this example was substantially the same as that used in example 1 except that 3 concentrations were set in step 2, and the ratios of the amounts of the hydrophobic silicone coupling agent and the tetraethyl orthosilicate were respectively:
(1) Concentration 1:0.1:1;
(2) Concentration 2:0.3:1;
(3) Concentration 3:0.6:1.
Wherein, the concentration 1 is the minimum concentration (0.6 mol/mL), and the configuration of the aerogel silica sol is carried out; the remaining concentration 2 (1.8 mol/mL) and concentration 3 (3.6 mol/mL) were used as gradient solvents.
Example 3
The preparation method used in this example was substantially the same as that used in example 1, except that the aerogel silica sol prepared in step 2 was 2 concentrations, calculated as the molar ratio of hydrophobic silicone coupling agent to ethyl orthosilicate, respectively:
(1) Concentration 1:0.1:1;
(2) Concentration 2:0.3:1.
Wherein, the concentration 1 is the minimum concentration (0.6 mol/mL), and the configuration of the aerogel silica sol is carried out; the remaining concentration 2 (1.8 mol/mL) was used as a gradient solvent.
Comparative example 1
The preparation method used in this comparative example was substantially the same as in example 1 except that the aerogel silica sol prepared in step 2 was 1 concentration, calculated as the ratio of the amounts of the hydrophobic silicone coupling agent and the tetraethyl orthosilicate: 1:1, concentration is 6mol/mL.
Comparative example 2
For comparison with the anisotropic structured composite fiber paper, the comparative example was conducted without the reduced pressure treatment in step 3, and the other preparation methods were substantially the same as in example 1.
Lateral comparative test experiment:
the composite fiber papers prepared in examples 1 to 3 and comparative examples 1 and 2 were respectively tested for high temperature resistance point, dimensional shrinkage of the highest high temperature resistance point and thermal conductivity at 300 c, and the test results were as follows:
table 2, results of heat resistance-level thermal conductivity test of the fibrous papers in examples and comparative examples
Remarks: in the group entries of the above table, real 1 is shorthand for example 1, real 2 is shorthand for example 2, real 3 is shorthand for example 3, 1 is shorthand for comparative example 1, and 2 is shorthand for comparative example 2.
Experimental results:
(1) As can be seen from the comparison of the data in table 2 and fig. 4 and 5, the lower the concentration gradient of aerogel silica sol used in the preparation of the composite fiber paper, the lower the highest heat resistance point reached. The maximum temperature resistance point of the composite fiber paper in the examples 1-3 obtained by the method provided by the invention is over 800 ℃, wherein the example 1 reaches 1020 ℃. Whereas comparative example 1 was only 750 ℃.
(2) The dimensional shrinkage of the highest temperature resistant point refers to the ratio of dimensional change of the material when the material thermally expands and thermally contracts at high temperatures. The higher this value, the greater the dimensional change of the material at high temperatures. From the experimental results, as the concentration gradient of the aerogel silica sol adopted is smaller, the dimensional shrinkage of the highest temperature resistant point is larger. Wherein comparative example 1 reached 24.2%.
(3) Thermal conductivity is a physical quantity describing the thermal conductivity of a material and represents the ability of a material to transfer heat under the influence of a temperature gradient per unit thickness per unit time. From the data in Table 2, and referring to FIG. 4, it can be seen that the more the gradient, the higher the thermal conductivity, with the addition of the silane coupling agent at different concentration gradients, wherein the percentages of example 1, example 2 and example 3, which employ the preparation method of the present invention, are 0.08 mW.m -1 ·K -1 、0.07mW·m -1 ·K -1 And 0.06 mW.m -1 ·K -1 In comparative example 1, in which the preparation method of the present invention was not adopted, the thermal conductivity at 300℃was only 0.04 mW.multidot.m due to the use of only one gradient -1 ·K -1 . This is because the fibrous paper is anisotropic from top to bottom, and this structure promotes better and more convenient heat transfer properties.
(4) Under the premise of other conditions and the same preparation method, in a transverse comparison test experiment, the surface structure and the morphology of the composite fiber paper prepared in the step 3 without pressure reduction treatment, namely under normal pressure are examined by a comparison example 2. In comparative example 2, the silane coupling agent (gradient solvent) was in a uniformly dispersed state due to no pressure reduction treatment during the reaction of the aerogel with the fiber paper, and thus functional and structural anisotropies could not be formed. Referring to the electron micrograph of fig. 3, comparative example 2 was not only structurally anisotropic but also greatly affected in thermal conductivity, and thus it was confirmed that the fibrous paper prepared at normal pressure in comparative example 2 was not anisotropic in both structure and function.
In a word, the preparation method provided by the invention utilizes in-situ growth of the silica sol layer with anisotropy on the basis of aluminum silicate fiber paper to obtain a porous elastic interconnection network and a firm and flexible composite structure, and the addition of the hydrophobic siloxane coupling agent reduces the crosslinking degree of the aerogel, so that the flexibility is improved, meanwhile, the aerogel silica sol with multiple concentration gradients is adopted, and the anisotropic aerogel is prepared by adopting the concentration gradient-based change in combination with a decompression method, so that the heat-resistant temperature of the fiber paper can be ensured, and the defect of reducing the heat transfer efficiency is avoided.
While the preferred embodiments and examples of the present invention have been described, it should be noted that those skilled in the art may make various modifications and improvements without departing from the inventive concept, including but not limited to, adjustments of proportions, procedures, and amounts, which fall within the scope of the present invention. While the preferred embodiments and examples of the present invention have been described, it should be noted that those skilled in the art may make various modifications and improvements without departing from the inventive concept, including but not limited to, adjustments of proportions, procedures, and amounts, which fall within the scope of the present invention.
Claims (10)
1. The preparation method of the normal-pressure drying anisotropic silicon-based aerogel composite fiber paper is characterized by comprising the following steps of:
s1, preparing at least two hydrophobic siloxane coupling agent solvents with different concentrations; preparing a hydrophobic siloxane coupling agent solvent with the minimum relative concentration, ethyl orthosilicate and a first organic solvent to obtain aerogel silica sol; and taking the rest concentration of the hydrophobic siloxane coupling agent solvent as a gradient solvent;
s2, laying aluminum silicate fiber paper, and adding the first organic solvent to the upper surface of the aluminum silicate fiber paper for wetting;
s3, adding the aerogel silica sol to the upper surface of the wetted aluminum silicate fiber paper under the conditions of normal temperature and normal pressure, so that the aerogel silica sol grows in situ on the surface of the aluminum silicate fiber paper to form a silica sol layer;
s4, sequentially adding the gradient solvents on the silica sol layer from small to large according to the concentration under the condition of decompression to form siloxane layers with different concentrations;
s5, performing aging and drying treatment and standing treatment to obtain the composite fiber paper;
preferably, in the step of sequentially adding the gradient solvents according to the concentration from small to large on the silica gel layer under the pressure-reduced state to form the siloxane layers with different concentrations, the pressure condition under the pressure-reduced state is not more than 0.098Mpa;
preferably, the hydrophobic siloxane coupling agent solvents of different concentrations are formulated based on the amount of the substance of the ethyl orthosilicate;
preferably, the ratio of the amounts of the ethyl orthosilicate and the hydrophobic silicone coupling agent substance ranges from 1 (0.1-1.0).
2. The method for preparing the normal pressure dry anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the aerogel silica sol is prepared from tetraethoxysilane, the hydrophobic siloxane coupling agent and the first organic solvent according to the mass ratio of 1 (0.1-1.0) to 10-50.
3. The method for preparing the normal pressure dry anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the hydrophobic siloxane coupling agent is any one or more of methyltrimethoxysilane, methyltriethoxysilane, dimethoxydiethoxysilane, phenyltriethoxysilane and trimethylmethoxysilane.
4. The method for preparing the normal pressure dry anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the first organic solvent is any one or more of methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, sec-butanol, pentanol and isomers thereof, hexanol and isomers thereof, and acetone.
5. The method for preparing the normal pressure dry anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the step of adding the aerogel silica sol to the upper surface of the wetted aluminum silicate fiber paper under the normal temperature and pressure conditions to enable the aerogel silica sol to grow on the surface of the aluminum silicate fiber paper in situ further comprises the step of standing;
preferably, the rest time is 0.5 hours to 3.0 hours.
6. The method for preparing the normal pressure dry anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the step S4 is characterized in that under the condition of reduced pressure, the gradient solvent is sequentially added on the silica sol layer from small to large according to the concentration, after the siloxane layers with different concentrations are formed, the hydrophobic siloxane coupling agent solvent with the next concentration is added after a preset interval time;
preferably, the preset interval time is 0.5 hours to 1.0 hours.
7. The method for preparing the normal pressure drying anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the aging drying treatment is as follows:
taking a second organic solvent as an aging liquid, and aging and drying under normal pressure;
preferably, the aging drying treatment is carried out for 12 hours to 60 hours;
preferably, the normal pressure state of the aging drying treatment is one atmospheric pressure state;
preferably, the second organic solvent is one or more of methanol, ethanol, propanol and acetone.
8. The method for preparing an anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the standing time of the standing treatment is 6 hours to 60 hours.
9. The method for preparing the normal pressure drying anisotropic silicon-based aerogel composite fiber paper according to claim 1, wherein the length of the aluminum silicate fiber paper is 1cm-50cm, the width of the aluminum silicate fiber paper is 1cm-10cm, and the thickness of the aluminum silicate fiber paper is 1mm-4mm.
10. A composite fiber paper prepared by the method for preparing the atmospheric pressure dry anisotropic silicon-based aerogel composite fiber paper according to any one of claims 1 to 9.
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