CN117384586A - Low-thixotropic dealcoholized organic silicon sealant and preparation method and application thereof - Google Patents
Low-thixotropic dealcoholized organic silicon sealant and preparation method and application thereof Download PDFInfo
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- CN117384586A CN117384586A CN202311483621.5A CN202311483621A CN117384586A CN 117384586 A CN117384586 A CN 117384586A CN 202311483621 A CN202311483621 A CN 202311483621A CN 117384586 A CN117384586 A CN 117384586A
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- 239000000565 sealant Substances 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title abstract description 20
- 229910052710 silicon Inorganic materials 0.000 title abstract description 20
- 239000010703 silicon Substances 0.000 title abstract description 20
- -1 polydimethylsiloxane Polymers 0.000 claims abstract description 41
- 239000004205 dimethyl polysiloxane Substances 0.000 claims abstract description 36
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims abstract description 36
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 26
- 230000009974 thixotropic effect Effects 0.000 claims abstract description 26
- 229910021485 fumed silica Inorganic materials 0.000 claims abstract description 23
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 15
- 239000003054 catalyst Substances 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 13
- 239000010936 titanium Substances 0.000 claims abstract description 12
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 12
- 239000006087 Silane Coupling Agent Substances 0.000 claims abstract description 11
- AMTWCFIAVKBGOD-UHFFFAOYSA-N dioxosilane;methoxy-dimethyl-trimethylsilyloxysilane Chemical compound O=[Si]=O.CO[Si](C)(C)O[Si](C)(C)C AMTWCFIAVKBGOD-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229940083037 simethicone Drugs 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims description 52
- 239000004590 silicone sealant Substances 0.000 claims description 34
- 239000000203 mixture Substances 0.000 claims description 28
- 239000013522 chelant Substances 0.000 claims description 21
- 238000002156 mixing Methods 0.000 claims description 20
- QWOVEJBDMKHZQK-UHFFFAOYSA-N 1,3,5-tris(3-trimethoxysilylpropyl)-1,3,5-triazinane-2,4,6-trione Chemical compound CO[Si](OC)(OC)CCCN1C(=O)N(CCC[Si](OC)(OC)OC)C(=O)N(CCC[Si](OC)(OC)OC)C1=O QWOVEJBDMKHZQK-UHFFFAOYSA-N 0.000 claims description 13
- NKSJNEHGWDZZQF-UHFFFAOYSA-N ethenyl(trimethoxy)silane Chemical compound CO[Si](OC)(OC)C=C NKSJNEHGWDZZQF-UHFFFAOYSA-N 0.000 claims description 12
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical group CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 claims description 6
- 125000003545 alkoxy group Chemical group 0.000 claims description 5
- NOGBEXBVDOCGDB-NRFIWDAESA-L (z)-4-ethoxy-4-oxobut-2-en-2-olate;propan-2-olate;titanium(4+) Chemical compound [Ti+4].CC(C)[O-].CC(C)[O-].CCOC(=O)\C=C(\C)[O-].CCOC(=O)\C=C(\C)[O-] NOGBEXBVDOCGDB-NRFIWDAESA-L 0.000 claims description 4
- HQYALQRYBUJWDH-UHFFFAOYSA-N trimethoxy(propyl)silane Chemical compound CCC[Si](OC)(OC)OC HQYALQRYBUJWDH-UHFFFAOYSA-N 0.000 claims description 4
- 238000004382 potting Methods 0.000 claims description 3
- XDLMVUHYZWKMMD-UHFFFAOYSA-N 3-trimethoxysilylpropyl 2-methylprop-2-enoate Chemical compound CO[Si](OC)(OC)CCCOC(=O)C(C)=C XDLMVUHYZWKMMD-UHFFFAOYSA-N 0.000 claims description 2
- JSYXMNQEKKZWHT-UHFFFAOYSA-L C(C)CC(=O)CC(=O)[O-].C(C)CC(=O)CC(=O)[O-].C(CC)O[Ti+2] Chemical compound C(C)CC(=O)CC(=O)[O-].C(C)CC(=O)CC(=O)[O-].C(CC)O[Ti+2] JSYXMNQEKKZWHT-UHFFFAOYSA-L 0.000 claims description 2
- FWDBOZPQNFPOLF-UHFFFAOYSA-N ethenyl(triethoxy)silane Chemical compound CCO[Si](OCC)(OCC)C=C FWDBOZPQNFPOLF-UHFFFAOYSA-N 0.000 claims description 2
- XYIBRDXRRQCHLP-UHFFFAOYSA-N ethyl acetoacetate Chemical compound CCOC(=O)CC(C)=O XYIBRDXRRQCHLP-UHFFFAOYSA-N 0.000 claims description 2
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 claims description 2
- JCGDCINCKDQXDX-UHFFFAOYSA-N trimethoxy(2-trimethoxysilylethyl)silane Chemical compound CO[Si](OC)(OC)CC[Si](OC)(OC)OC JCGDCINCKDQXDX-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 2
- NBXZNTLFQLUFES-UHFFFAOYSA-N triethoxy(propyl)silane Chemical compound CCC[Si](OCC)(OCC)OCC NBXZNTLFQLUFES-UHFFFAOYSA-N 0.000 claims 1
- 238000003860 storage Methods 0.000 abstract description 15
- 230000000052 comparative effect Effects 0.000 description 21
- 239000006229 carbon black Substances 0.000 description 13
- 125000001891 dimethoxy group Chemical group [H]C([H])([H])O* 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 125000000118 dimethyl group Chemical group [H]C([H])([H])* 0.000 description 9
- XNGIFLGASWRNHJ-UHFFFAOYSA-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 0.000 description 9
- 229920002545 silicone oil Polymers 0.000 description 9
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical class [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 8
- 238000001816 cooling Methods 0.000 description 8
- 238000007599 discharging Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 230000032683 aging Effects 0.000 description 5
- 238000009472 formulation Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 229910000019 calcium carbonate Inorganic materials 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- INFDPOAKFNIJBF-UHFFFAOYSA-N paraquat Chemical compound C1=C[N+](C)=CC=C1C1=CC=[N+](C)C=C1 INFDPOAKFNIJBF-UHFFFAOYSA-N 0.000 description 3
- HDPNBNXLBDFELL-UHFFFAOYSA-N 1,1,1-trimethoxyethane Chemical compound COC(C)(OC)OC HDPNBNXLBDFELL-UHFFFAOYSA-N 0.000 description 2
- 229910002808 Si–O–Si Inorganic materials 0.000 description 2
- 239000007822 coupling agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 229920001296 polysiloxane Polymers 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- BPSIOYPQMFLKFR-UHFFFAOYSA-N trimethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane Chemical compound CO[Si](OC)(OC)CCCOCC1CO1 BPSIOYPQMFLKFR-UHFFFAOYSA-N 0.000 description 2
- 239000002318 adhesion promoter Substances 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- GCSJLQSCSDMKTP-UHFFFAOYSA-N ethenyl(trimethyl)silane Chemical compound C[Si](C)(C)C=C GCSJLQSCSDMKTP-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000012763 reinforcing filler Substances 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- YUYCVXFAYWRXLS-UHFFFAOYSA-N trimethoxysilane Chemical compound CO[SiH](OC)OC YUYCVXFAYWRXLS-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J183/00—Adhesives based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Adhesives based on derivatives of such polymers
- C09J183/04—Polysiloxanes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/04—Non-macromolecular additives inorganic
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2203/00—Applications
- C08L2203/20—Applications use in electrical or conductive gadgets
- C08L2203/206—Applications use in electrical or conductive gadgets use in coating or encapsulating of electronic parts
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
- C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention relates to a low-thixotropic dealcoholized organic silicon sealant, a preparation method and application thereof, wherein the organic silicon sealant comprises the following components: 60 to 80 parts by weight of alkoxy-terminated polydimethylsiloxane, 15 to 30 parts by weight of simethicone, 2 to 8 parts by weight of fumed silica, 0 to 0.5 part by weight of color paste, 1 to 3 parts by weight of cross-linking agent, 0.2 to 1 part by weight of silane coupling agent and 1 to 3 parts by weight of organic titanium catalyst; wherein, the organosilicon sealant is treated by a method comprising the following steps: heat treatment is carried out for 1-3 h at the temperature of 45-65 ℃ and under negative pressure of minus 0.090 to minus 0.099 MPa. The low thixotropic dealcoholized organosilicon sealant has low thixotropic property and good storage stability.
Description
Technical Field
The invention belongs to the technical field of organic silicon sealants, and particularly relates to a low-thixotropic dealcoholized organic silicon sealant, and a preparation method and application thereof.
Background
The dealcoholized organosilicon sealant is neutral, has the advantages of environmental protection, no toxicity, no corrosiveness, good bonding performance and the like, is popular with industry attention and researchers in recent years, and is widely applied to various fields of buildings, electronics, automobiles, LEDs, household appliances, new energy sources and the like. When used for coating a Printed Circuit Board (PCB) and encapsulating components, the sealant needs to have low viscosity and low thixotropic property so as to ensure that the product spreads well on the surface of the PCB and fills in a narrow gap,
in the preparation process of the dealcoholized organosilicon sealant, hydroxyl-containing micromolecular substances, especially alcohols, are inevitably generated in the system, and the hydroxyl-containing substances are extremely easy to attack the Si-O-Si main chain of the siloxane polymer under the catalysis of a catalyst or the high-temperature baking, so that the Si-O-Si main chain is broken, and low-activity hydroxyl-terminated oligomer and almost-inactive monoalkoxy-terminated oligomer are generated, so that the curing speed of the sealant is obviously slowed down, even the sealant cannot be cured for a long time, and the storage stability of the dealcoholized organosilicon sealant is seriously affected.
Chinese patent CN112898948B discloses a single-component transparent organic silicon sealant and a preparation method thereof, and the single-component transparent organic silicon sealant adopts alkoxy end-capped silicon rubber, and is high in transparency, excellent in bonding strength and resistant to long-term boiling by matching with fumed silica, an alcohol cross-linking agent and an adhesion promoter, so that the single-component transparent organic silicon sealant can be widely applied to the field of electronic appliances.
Chinese patent CN114196371a discloses a dealcoholized silicone structural sealant, comprising the following components: alpha, omega-dihydroxy polydimethylsiloxane, nano activated calcium carbonate, two reinforcing fillers, a cross-linking agent, a coupling agent and a phthalate vulcanizing machine. The invention can solve the problem that the strength of the traditional dealcoholized silicone structural sealant is obviously reduced after long-term use at high temperature, has excellent weather resistance, can maintain excellent tensile bonding strength after long-term use at high temperature, and has no corrosion to most building materials.
Chinese patent CN111019593B discloses an equal proportion mixed organosilicon sealant for anti-fog vehicle lamp and its preparation method, wherein component a comprises: alpha, omega-dihydroxy polydimethylsiloxane, nano activated calcium carbonate, white carbon black and plasticizer; the component B comprises: base material, pigment, plasticizer, cross-linking agent, coupling agent and catalyst. Compared with the traditional double-component silicone sealant, the A, B component equal proportion mixed use has the advantages of low requirement on proportioning precision of gluing equipment, high curing speed and no influence on an anti-fog coating in an anti-fog car lamp.
The existing dealcoholized organosilicon sealant is not concerned about thixotropic property, only various advantages of the sealant after curing are mentioned, and the storage stability is not examined. For PCB coating and component potting, low thixotropic is an extremely important property, while good storage stability is an important prerequisite for commercial application of the product. Accordingly, there is a need to provide new dealcoholized silicone sealants with reduced thixotropic properties and improved storage stability of the sealant product.
Disclosure of Invention
In view of the above, the present invention aims to provide a low thixotropic dealcoholized silicone sealant, a preparation method and application thereof, which have low thixotropic property and good storage stability, aiming at the problems existing in the prior art.
The object of the present invention is achieved by the following technical problems.
In a first aspect, the present invention provides a low thixotropic dealcoholized silicone sealant, wherein the silicone sealant comprises: 60 to 80 parts by weight of alkoxy-terminated polydimethylsiloxane, 15 to 30 parts by weight of simethicone, 2 to 8 parts by weight of fumed silica, 0 to 0.5 part by weight of color paste, 1 to 3 parts by weight of cross-linking agent, 0.2 to 1 part by weight of silane coupling agent and 1 to 3 parts by weight of organic titanium catalyst; wherein, the organosilicon sealant is treated by a method comprising the following steps: heat treatment is carried out for 1-3 h at the temperature of 45-65 ℃ and under negative pressure of minus 0.090 to minus 0.099 MPa.
In the invention, alkoxy end-capped polydimethylsiloxane, simethicone, white carbon black, silane coupling agent and the like are matched with each other, and the organosilicon sealant has low thixotropic property and improved storage stability after being treated by a specific method. Without wishing to be bound by theory, it is believed that heat treatment at a specific temperature and high negative pressure, the silicone sealant components interact to form a stable system with low thixotropic properties; and after heat treatment, alcohol micromolecules (trace moisture is inevitably present in the product) generated by hydrolysis of the cross-linking agent, and small molecule substances such as siloxane ring bodies which possibly contain the alcohol micromolecules have little residue, so that damage of the residual micromolecules to an organosilicon sealant stabilizing system is reduced, and the organosilicon sealant has improved storage stability.
The organic silicon sealant provided by the invention, wherein the alkoxy end-capped polydimethylsiloxane is selected from one or more of dimethoxy end-capped polydimethylsiloxane, trimethoxy ethane end-capped polydimethylsiloxane and triethoxy end-capped polydimethylsiloxane, and preferably dimethoxy end-capped polydimethylsiloxane and trimethoxy ethane end-capped polydimethylsiloxane.
The silicone sealant provided by the invention has the viscosity of 100-3000 mPas, preferably 500-2000 mPas, more preferably 750-1500 mPas at 25 ℃.
The silicone sealant provided according to the present invention, wherein the amount of the alkoxy-terminated polydimethylsiloxane may be 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, or a range of its composition.
The silicone sealant provided by the invention has the viscosity of 50-350 mPas, preferably 50-100 mPas, at 25 ℃.
The organic silicon sealant provided by the invention can be unmodified or hydrophobically modified. In some embodiments, the fumed silica is a hydrophobically modified silica. For example, fumed silica, available from cabot corporation under the designation ST 55.
In the invention, the specific surface area of the fumed silica can be 80-200 m 2 And/g. For example, the specific surface area of the fumed silica can be 80m 2 /g、100m 2 /g、150m 2 /g、200m 2 /g or a range of its composition. It is thought that excessive specific surface area of fumed silica results in high thixotropic properties.
The silicone sealant provided by the invention can be used in an amount of 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight or a composition range thereof.
The organosilicon sealant provided by the invention, wherein the cross-linking agent is selected from methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, hexamethoxydisilylethane and hexaethoxydisilylethane, preferably from methyltrimethoxysilane and vinyltrimethoxysilane.
The silicone sealant provided by the invention can be used in an amount of 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight or a composition range thereof.
The organic silicon sealant provided by the invention, wherein the color paste can be added according to the requirements of the final use of the organic silicon sealant. Examples of color pastes suitable for use in the present invention include, but are not limited to: carbon black color paste.
When the color paste is used, the amount of the color paste can be 0.1 part by weight, 0.2 part by weight, 0.5 part by weight, 0.6 part by weight, 0.8 part by weight, 1 part by weight or a composition range thereof.
The organic silicon sealant provided by the invention, wherein the silane coupling agent is selected from one or more of gamma- (2, 3-epoxypropoxy) propyl trimethoxysilane, gamma- (2, 3-epoxypropoxy) propyl triethoxysilane, tris [3- (trimethoxysilyl) propyl ] isocyanurate, gamma-methacryloxypropyl trimethoxysilane and gamma-methacryloxymethyl trimethoxysilane, and is preferably selected from tris [3- (trimethoxysilyl) propyl ] isocyanurate and gamma- (2, 3-epoxypropoxy) propyl trimethoxysilane.
The silicone sealant according to the present invention, wherein the amount of the silane coupling agent may be 0.3 parts by weight, 0.5 parts by weight, 0.8 parts by weight, 1 part by weight, or a range of its composition.
The organic silicon sealant provided by the invention, wherein the organic titanium catalyst can be titanate chelate. The titanate chelate is selected from one or more of titanium chelate of ethyl acetoacetate, diisopropoxytitanium bis (ethyl acetoacetate) chelate and 1, 3-propoxytitanium bis (ethyl acetoacetate) chelate, preferably diisopropoxytitanium bis (ethyl acetoacetate) chelate.
The organic silicon sealant provided by the invention, wherein the amount of the organic titanium catalyst can be 1 part by weight, 1.2 parts by weight, 1.5 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.5 parts by weight, 3 parts by weight or a composition range thereof.
The organic silicon sealant provided by the invention is treated by a method comprising the following steps: heat-treating at a temperature of 50-60 ℃ and a negative pressure of-0.095 to-0.099 MPa for 1-2 hours, for example, 1-1.5 hours.
The organic silicon sealant provided by the invention is characterized in that the treatment is carried out under the stirring condition. The stirring speed is preferably 100 to 500 rpm, more preferably 250 to 350 rpm.
In a second aspect, the present invention provides a method for preparing the silicone sealant of the first aspect, wherein the preparation method comprises the following steps:
s100, mixing alkoxy end-capped polydimethylsiloxane, simethicone, fumed silica, optional color paste, a cross-linking agent, a silane coupling agent and an organic titanium catalyst to obtain a mixture;
s200, carrying out heat treatment on the mixture obtained in the step S100 at the temperature of 45-65 ℃ and under negative pressure of minus 0.090 to minus 0.099MPa for 1-3 h.
The preparation method provided by the invention, wherein the step S100 comprises the following steps:
s110, carrying out first vacuum mixing on alkoxy-terminated polydimethylsiloxane, fumed silica and optional color paste at 10-35 ℃, preferably 20-30 ℃ to obtain a first mixture;
s120, adding simethicone and a cross-linking agent into the first mixture, and carrying out second vacuum mixing at 10-35 ℃, preferably 20-30 ℃ to obtain a second mixture;
s130, adding a silane coupling agent and an organic titanium catalyst into the second mixture, and carrying out third vacuum mixing at 10-35 ℃, preferably 20-30 ℃ to obtain the mixture.
Preferably, the time of the first vacuum mixing is 20-40 min; and/or the time of the second vacuum mixing and the time of the third vacuum mixing are each independently 5 to 20min, preferably 10 to 15min.
Preferably, the first vacuum mixing, the second vacuum mixing and the third vacuum mixing are each independently performed under stirring conditions. The stirring speed is preferably 100 to 500 rpm, more preferably 250 to 350 rpm.
According to the preparation method provided by the invention, the conditions of the heat treatment in the step S200 include: the temperature is 50-60 ℃; and/or the pressure is-0.095 to-0.099 MPa; and/or for a time of 1 to 2 hours, for example, 1 to 1.5 hours.
In a third aspect, the present invention provides the use of the silicone sealant of the first aspect and the silicone sealant prepared by the preparation method of the second aspect in printed circuit board coating and component potting.
The invention has at least the following technical effects:
(1) The organic silicon sealant has small thixotropic property, and the thixotropic index can be as low as below 1.1;
(2) The organic silicon sealant disclosed by the invention has good storage stability, and the thixotropic index and the surface dry time change rate before and after aging are small; in addition, the organosilicon sealant of the invention adopts the gas phase white carbon black, has small dosage and low density (usually 1.05 g/cm) -1 The method is particularly suitable for coating a printed circuit board and encapsulating components;
(3) The preparation method of the invention has simple and convenient operation and is easy to popularize and apply.
Detailed Description
The invention is further illustrated below with reference to specific examples.
The raw materials used in the examples and comparative examples of the present invention are as follows:
dimethoxy end-capped polydimethylsiloxane, P50 series, D3-D10 ring content less than 0.1%, jiangxi blue Star fire organosilicon Co;
trimethoxy-silane-terminated polydimethylsiloxane, O-FT series, D3-D10 ring content < 0.1%, new orange Material (Guangzhou) Co., ltd;
alpha, omega-dihydroxy polydimethylsiloxane (107 glue), P48V750, viscosity 750 mPa.s, D3-D10 ring content < 0.1%, jiangxi blue Star fire organosilicon Co., ltd;
fumed silica, ST55, cabot corporation;
calcium carbonate, CCS-25, guangxi Huana New Material Co., ltd;
carbon black paste, incorporated new material limited of san (Shanghai);
simethicone, H47 series, jiangxi blue Starfire organosilicon Co., ltd;
methyltrimethoxysilane, vinyltrimethylsilane, gamma- (2, 3 glycidoxy) propyltrimethoxysilane, hubei New blue sky New Material Co., ltd;
titanate chelate Ti-726, tris [3- (trimethoxysilyl) propyl ] isocyanurate, guangzhou solid chemical industry Co.
The raw materials not shown are all common materials in the field and can be obtained commercially or self-made.
Example 1
Adding 70 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 750 mPas, 6 parts by weight of fumed silica and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then 0.2 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts of the phthalate chelate Ti-726 were added and stirring was continued for 10min. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 55deg.C for 1 hr, cooling to room temperature, and discharging. The stirring speed in example 1 was 300 rpm.
Example 2
The formulation and preparation method of the silicone sealant were substantially the same as in example 1, except that: the heat treatment temperature was 45 ℃.
Example 3
The formulation and preparation method of the silicone sealant were substantially the same as in example 1, except that: the heat treatment temperature was 60 ℃.
Example 4
The formulation and preparation method of the silicone sealant were substantially the same as in example 1, except that: the heat treatment temperature was 65 ℃.
Example 5
The formulation and preparation method of the silicone sealant were substantially the same as in example 1, except that: the heat treatment time was 3 hours.
Example 6
The formulation and preparation method of the silicone sealant were substantially the same as in example 1, except that: during the heat treatment, the stirring speed was 100 rpm.
Example 7
Adding 61 parts by weight of trimethoxy silane end-capped polydimethylsiloxane with the viscosity of 1500 mPa.s and 3 parts by weight of fumed silica into a reaction kettle, vacuumizing (the vacuum degree is < -0.095 MPa), and stirring for 30min at normal temperature; adding 30 parts by weight of dimethyl silicone oil with the viscosity of 100 mPas and 3 parts by weight of methyltrimethoxysilane, and continuously stirring for 10min; then, 1 part by weight of gamma- (2, 3-glycidoxy) propyltrimethoxysilane and 2 parts by weight of Ti726 were added and stirring was continued for 10 minutes. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 45deg.C for 1.5 hr, cooling to room temperature, and discharging. The stirring speed in example 6 was 300 rpm.
Example 8
Adding 75 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 800 mPas, 5 parts by weight of fumed silica and 0.5 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 15 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then 0.3 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 2.2 parts by weight of the phthalate chelate Ti-726 were added and stirring was continued for 10min. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 65deg.C for 1 hr, cooling to room temperature, and discharging. The stirring speed in example 7 was 300 rpm.
Comparative example 1
Adding 70 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 750 mPas, 6 parts by weight of fumed silica and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then, 0.2 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts by weight of Ti-726 as phthalate chelate were added, and the mixture was stirred for 70 minutes and discharged. The stirring speed in comparative example 1 was 300 rpm.
Comparative example 2
Adding 70 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 750 mPas, 6 parts by weight of fumed silica and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas, heating, maintaining vacuumizing (vacuum degree is < -0.095 MPa) in the whole course, stirring, and performing heat treatment at 95 ℃ for 1h; then cooling to room temperature, adding 2 parts of vinyl trimethoxy silane, and stirring for 10min in vacuum; finally, 0.2 part of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts of phthalate chelate Ti-726 are added, and the mixture is discharged after stirring for 10 minutes. The stirring speed in comparative example 2 was 300 rpm.
Comparative example 3
Adding 70 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 750 mPas, 6 parts by weight of fumed silica and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then 0.2 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts by weight of the phthalate chelate Ti-726 were added and stirring was continued for 10min. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 70deg.C for 1 hr, cooling to room temperature, and discharging. The stirring speed in comparative example 3 was 300 rpm.
Comparative example 4
Adding 70 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 750 mPas, 6 parts by weight of fumed silica and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then 0.2 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts of the phthalate chelate Ti-726 were added and stirring was continued for 10min. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 40deg.C for 2 hr, cooling to room temperature, and discharging. The stirring speed in comparative example 4 was 300 rpm.
Comparative example 5
Adding 70 parts by weight of P48V750 with the viscosity of 750 mPas, 6 parts by weight of fumed silica and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30min at normal temperature under vacuum degree of minus 0.095 MPa; adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then 0.2 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts of the phthalate chelate Ti-726 were added and stirring was continued for 10min. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 55deg.C for 1 hr, cooling to room temperature, and discharging. The stirring speed in comparative example 5 was 300 rpm.
Comparative example 6
Adding 70 parts by weight of dimethoxy end-capped polydimethylsiloxane with the viscosity of 750 mPas, 70 parts by weight of calcium carbonate CCS-25 (pre-dried until the moisture content is less than 0.1 percent) and 0.2 part by weight of carbon black color paste into a reaction kettle, and stirring for 30 minutes at normal temperature under vacuum (the vacuum degree is less than-0.095 MPa); adding 20 parts by weight of dimethyl silicone oil with the viscosity of 50 mPas and 2 parts by weight of vinyl trimethoxy silane, and continuously stirring for 10min; then 0.2 parts by weight of tris [3- (trimethoxysilyl) propyl ] isocyanurate and 1.8 parts of the phthalate chelate Ti-726 were added and stirring was continued for 10min. Then heating, maintaining vacuum (vacuum degree < -0.095 MPa), stirring, heat treating at 55deg.C for 1 hr, cooling to room temperature, and discharging.
The stirring speed in example 1 was 300 rpm.
The product of comparative example 6, which contains too much calcium carbonate, has a density of 1.31g/cm -1 It is not suitable for coating printed circuit board and encapsulating components, so the invention does not test the performance of the printed circuit board.
Performance testing
The silicone sealants of examples and comparative examples were subjected to the relevant tests as follows.
1. Thixotropic evaluation method
Thixotropic index is used for judging the thixotropic property. After the product is stood for at least 12 hours under standard conditions (25 ℃/50%RH), a rotational viscometer is used for testing the viscosity, and the ratio of the viscosity at the rotating speed X to the viscosity at the rotating speed 10X is the thixotropic index (the viscosity is measured according to the method described in GB/T2794-2013).
2. Method for evaluating storage stability
Placing the sealed tube filled with the organosilicon sealant into a baking oven at 70 ℃ for 7 days, taking out the sealed tube after expiration, standing for 24 hours at room temperature, and then testing viscosity and surface drying time; and comparing the test result with the initial value to calculate the variation amplitude. When the absolute value of the variation amplitude is less than 30%, it is indicated that the storage stability is good.
The surface dry time GB/T13477-2002 is measured by the method; tensile strength and elongation at break were measured according to the methods described in GB/T528-1998; shore hardness was measured according to the method described in GB/T531-1999.
Table 1 silicone sealant properties of examples and comparative examples
As can be seen from Table 1, the thixotropic index of examples 1 to 8 of the present application is very low, and the change amplitude is also small after aging for 7 days at 70 ℃ and is all below 20%; meanwhile, the change amplitude of the tack-free time of examples 1 to 8 before and after aging is also significantly smaller than that of comparative examples 1 to 5. Comparative example 1 does not have a heat treatment step, and the product has greater thixotropic properties and poor storage stability as compared with example 1; comparative example 2, which was subjected to a high-temperature heat treatment before adding the crosslinking agent, the thixotropic index of the product was large and the storage stability was poor; comparative example 3 was heat-treated at 70 c, the surface drying rate was high, and after aging at 70 c x 7 days, the product had been approximately cured and could not be tested, probably because the crosslinking agent was easily removed at 70 c under vacuum conditions, and the surface drying rate of the product became high; comparative example 4 was heat-treated at 40℃for 2 hours, the heat treatment temperature was too low, and after aging for 7 days at 70℃the thixotropic index of the product was large and the storage stability was remarkably poor; comparative example 5 replaced the dimethoxy-terminated polydimethylsiloxane with P48V750 of 750 mPas, which may be caused by hydrogen bonding with an organotitanium catalyst, the thixotropic index was large. The comparison of the data fully shows that the dealcoholized organosilicon sealant has low thixotropic property and good storage stability.
Claims (10)
1. A low thixotropic dealcoholized silicone sealant, wherein the silicone sealant comprises: 60 to 80 parts by weight of alkoxy-terminated polydimethylsiloxane, 15 to 30 parts by weight of simethicone, 2 to 8 parts by weight of fumed silica, 0 to 0.5 part by weight of color paste, 1 to 3 parts by weight of cross-linking agent, 0.2 to 1 part by weight of silane coupling agent and 1 to 3 parts by weight of organic titanium catalyst; wherein, the organosilicon sealant is treated by a method comprising the following steps: heat treatment is carried out for 1-3 h at the temperature of 45-65 ℃ and under negative pressure of minus 0.090 to minus 0.099 MPa.
2. The silicone sealant according to claim 1, wherein the alkoxy-terminated polydimethylsiloxane is selected from one or more of dimethoxy-terminated polydimethylsiloxane, trimethoxy-ethane-terminated polydimethylsiloxane, triethoxy-terminated polydimethylsiloxane, preferably dimethoxy-terminated polydimethylsiloxane and trimethoxy-ethane-terminated polydimethylsiloxane;
and/or the viscosity of the alkoxy-terminated polydimethylsiloxane is 100 to 3000 mPas, preferably 500 to 2000 mPas, more preferably 750 to 1500 mPas at 25 ℃.
3. The silicone sealant according to claim 1 or 2, wherein the viscosity of the simethicone is 50 to 350 mPa-s, preferably 50 to 100 mPa-s, at 25 ℃.
4. The silicone sealant according to any one of claims 1-3, wherein the fumed silica is hydrophobically modified silica.
5. The silicone sealant according to any one of claims 1-4, wherein the cross-linking agent is selected from methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, hexamethoxydisilylethane and hexaethoxydisilylethane, preferably from methyltrimethoxysilane and vinyltrimethoxysilane.
6. The silicone sealant according to any one of claims 1-5, wherein the silane coupling agent is selected from one or more of gamma- (2, 3 glycidoxy) propyltrimethoxysilane, gamma- (2, 3 glycidoxy) propyltriethoxysilane, tris [3- (trimethoxysilyl) propyl ] isocyanurate, gamma-methacryloxypropyl trimethoxysilane, gamma-methacryloxymethyl trimethoxysilane, preferably selected from tris [3- (trimethoxysilyl) propyl ] isocyanurate and gamma- (2, 3 glycidoxy) propyl trimethoxysilane;
and/or, the organic titanium catalyst is titanate chelate; the titanate chelate is preferably selected from one or more of titanium chelate of ethyl acetoacetate, diisopropoxytitanium bis (ethyl acetoacetate) chelate, 1, 3-propoxytitanium bis (ethyl acetoacetate) chelate, more preferably diisopropoxytitanium bis (ethyl acetoacetate) chelate.
7. The silicone sealant according to any one of claims 1-6, wherein the silicone sealant is treated by a method comprising: heat-treating at a temperature of 50-60 ℃ and a negative pressure of-0.095 to-0.099 MPa for 1-3 hours, for example, 1-2 hours;
and/or, the treatment is performed under stirring conditions; the stirring speed is preferably 100 to 500 rpm, more preferably 250 to 350 rpm.
8. The method for producing the silicone sealant according to any one of claims 1 to 7, wherein the method for producing comprises the steps of:
s100, mixing alkoxy end-capped polydimethylsiloxane, simethicone, fumed silica, optional color paste, a cross-linking agent, a silane coupling agent and an organic titanium catalyst to obtain a mixture;
s200, carrying out heat treatment on the mixture obtained in the step S100 at the temperature of 45-65 ℃ and under negative pressure of minus 0.090 to minus 0.099MPa for 1-3 h.
9. The preparation method according to claim 8, wherein the step S100 comprises the steps of:
s110, carrying out first vacuum mixing on alkoxy-terminated polydimethylsiloxane, fumed silica and optional color paste at 10-35 ℃, preferably 20-30 ℃ to obtain a first mixture;
s120, adding simethicone and a cross-linking agent into the first mixture, and carrying out second vacuum mixing at 10-35 ℃, preferably 20-30 ℃ to obtain a second mixture;
s130, adding a silane coupling agent and an organic titanium catalyst into the second mixture, and carrying out third vacuum mixing at 10-35 ℃, preferably 20-30 ℃ to obtain a mixture;
preferably, the time of the first vacuum mixing is 20-40 min; and/or the time of the second vacuum mixing and the time of the third vacuum mixing are each independently 5 to 20min, preferably 10 to 15min;
preferably, the first vacuum mixing, the second vacuum mixing, and the third vacuum mixing are each independently performed under stirring conditions; the stirring speed is preferably 100 to 500 rpm, more preferably 250 to 350 rpm;
and/or, the heat treatment conditions in the step S200 include: the temperature is 50-60 ℃; and/or the pressure is-0.095 to-0.099 MPa; and/or for a time of 1 to 3 hours, for example, 1 to 1.5 hours.
10. Use of the silicone sealant according to any one of claims 1 to 7 or the prepared silicone sealant according to claim 8 or 9 in printed circuit board coating and component potting.
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