Moisture and heat dual-cured silicone sealant and method of making the same

Abstract

The application discloses a heat and moisture dual-cured silicone sealant and a preparation method thereof. The silicone sealant is prepared from raw materials including a hydroxyl-terminated methyl vinyl polysiloxane, an alkoxy-terminated polydimethylsiloxane, active nano calcium carbonate, fumed silica, a crosslinking agent, a catalyst and an adhesion promoter. The silicone sealant has the advantages of both condensation and addition curing systems, can be quickly positioned and cured, has high strength and good adhesion after curing, has excellent temperature resistance and a long storage period, and can be used in various occasions requiring quick positioning and assembly.

Description

Technical Field

[0001] This invention belongs to the field of silicone sealant technology, and more specifically, this invention relates to a silicone sealant that undergoes dual curing by heat and moisture and its preparation method. Background Technology

[0002] Based on their curing mechanisms, silicone sealants can be broadly classified into two categories: condensation-type and addition-type, each with its own characteristics. Condensation-type silicone sealants are formulated from base polymers, crosslinking agents, catalysts, fillers, and additives. The sealant is sealed in a flexible tube or plastic tube; when used, the sealant is extruded and vulcanizes into an elastomer upon contact with moisture at room temperature. This makes them particularly convenient to use and they are widely used in home appliances, automobiles, electronics, machinery, and chemical industries. Addition-type silicone sealants are based on hydrosilylation reactions. Vinyl-containing polysiloxanes and hydrogen-containing polysiloxanes crosslink under the catalysis of platinum complexes to form elastomers. They feature no byproducts, environmental friendliness, high conversion rate, low shrinkage, and easy control of crosslinking density and speed.

[0003] In today's increasingly integrated industrial production with information technology and intelligent manufacturing, conventional single-component condensation-type silicone sealants face problems such as long curing times, low strength, and insufficient temperature resistance. Addition-type silicone sealants, on the other hand, have curing speeds and adhesive strengths limited by temperature, typically requiring higher temperatures and longer heating times to achieve good adhesion to the substrate. Furthermore, before the sealant cures, the workpiece requires additional mechanical holding and support, failing to meet the requirements for rapid positioning and assembly. Since the two curing systems use different base polymers, crosslinking agents, and catalysts, physically mixing them has several drawbacks. First, the primary or secondary aminosilanes added to the condensation-type system can poison the caster catalyst used in the addition-type system, preventing curing and thus hindering rapid positioning. Second, the polymers in the two systems will not undergo crosslinking reactions; the temperature resistance and strength of the mixture depend solely on the proportion of the addition-type system, while the temperature resistance and strength of the condensation-type system will not be improved by physical mixing.

[0004] Existing technologies have seen numerous attempts to combine two or more curing systems. For example, using acrylic and silicone polymers for composite modification can yield products with both UV and moisture curing capabilities, which can address the rapid positioning issue to some extent. However, UV irradiation can only affect exposed areas of the sealant surface. For areas inside the workpiece or in shadow areas that are difficult to cover with UV irradiation, curing can only be achieved gradually through contact with moisture in the air, limiting its application. Furthermore, products with both UV and moisture curing exhibit low adhesion strength and poor temperature resistance due to the lower temperature at which they bond with the substrate. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide an organosilicon sealant that can simultaneously satisfy rapid positioning and rapid curing, high strength, good adhesion, excellent temperature resistance and long shelf life.

[0006] The specific technical solutions for achieving the above-mentioned objectives are as follows.

[0007] In a first aspect, the present invention provides a heat and moisture dual-curing silicone sealant, comprising the following raw material components in parts by weight:

[0008]

[0009] The hydroxyl-terminated methyl vinyl polysiloxane is a polysiloxane whose molecular chain contains hydroxyl groups at both ends and contains [(CH2=CH)(CH3)Si-O] and [(CH3)2Si-O] links in the molecular chain, and the ratio of the number of [(CH2=CH)(CH3)Si-O] links to the number of [(CH3)2Si-O] links is 0.5 to 5:100;

[0010] The alkoxy-terminated polydimethylsiloxane has the structure shown in formula (1):

[0011] (R 1 O)2(R 2 )Si-O-[(CH3)2SiO] n -Si(OR 1 )2(R 3 (1)

[0012] Among them, R 1 R 2 and R 3 R is a monovalent hydrocarbon group that is either substituted or unsubstituted. 1 R 2 and R 3 Whether they are the same or different, n is an integer between 100 and 1500.

[0013] A second aspect of the present invention provides a method for preparing a heat and moisture dual-curing silicone sealant, comprising the following steps:

[0014] (1) Hydroxyl-terminated methyl vinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano calcium carbonate and fumed silica are vacuum dehydrated at 110℃~130℃ for 120 minutes~180 minutes and cooled under nitrogen protection to obtain the base material.

[0015] (2) At room temperature, the base material obtained in step (1) is stirred under vacuum with crosslinking agent, catalyst and thickener for 40 to 60 minutes.

[0016] In this invention, hydroxyl-terminated methylvinyl polysiloxane and alkoxy-terminated polydimethylsiloxane are used as base polymers, a mixture of alkoxysilane or its oligomers and hydrogen-containing polysiloxane is used as a crosslinking agent, a mixture of titanate complex and a specific type of platinum catalyst is used as a catalyst, and tackifiers and other components are added to prepare an organosilicon sealant with dual heat and moisture curing properties. When the organosilicon sealant is heated to a corresponding temperature (around 130°C), the vinyl groups in the hydroxyl-terminated methylvinyl polysiloxane and the hydrogen-containing polysiloxane in the crosslinking agent undergo an addition reaction under the action of a platinum catalyst, which allows the organosilicon sealant to pre-cur in a relatively short time (around 15 minutes), forming an elastomer with certain tensile strength, shear strength and initial tack, to meet the requirements of rapid positioning of the workpiece in the early stage; at the same time, the heat pre-curing can also promote better bonding between the alkoxy groups in the tackifier and the groups on the surface of the substrate, improving the bonding strength between the sealant and the substrate. After pre-curing by heat, the elastomer comes into contact with moisture in the air. The alkoxysilane or its oligomer in the crosslinking agent hydrolyzes under the catalysis of the titanate complex. It further condenses and crosslinks with the hydroxyl groups in the hydroxyl-terminated methyl vinyl polysiloxane and the alkoxy groups in the alkoxy-terminated polydimethylsiloxane, and completes the curing process. This increases the crosslinking density of the sealant, further improves its shear strength, and gives it excellent temperature resistance. After aging at 250℃ for 168h, the shear strength retention rate is over 80%. Under the combined action of all the raw material components of this invention, the silicone sealant of this invention organically combines the advantages of both condensation and addition curing systems. It can be quickly positioned and cured, and after curing, it has high strength, good adhesion, and excellent temperature resistance. It can be used in various occasions that require rapid positioning and assembly.

[0017] The silicone sealant of the present invention requires simple equipment for heat pre-curing and is easy to operate. The pre-curing speed of the sealant is only affected by temperature, avoiding the problem that UV irradiation cannot cover the inside of the workpiece or the shaded area.

[0018] Furthermore, by selecting the type of platinum catalyst and controlling its addition amount, and by adding an appropriate amount of tackifier, the polar groups in the tackifier coordinate with the platinum catalyst to a certain extent, inhibiting the catalytic activity of the platinum catalyst at room temperature. This allows the heat and moisture dual-curing silicone sealant of the present invention to be packaged in a single-component form, eliminating the need for metering and mixing, thus improving ease of use. It can also be stored stably at room temperature with a long shelf life, avoiding the problem that current single-component addition-type silicone sealants usually require refrigerated storage. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0021] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0022] In some embodiments of the present invention, a heat and moisture dual-curing silicone sealant is disclosed, comprising the following raw material components in parts by weight:

[0023]

[0024] The hydroxyl-terminated methyl vinyl polysiloxane is a polysiloxane whose molecular chain contains hydroxyl groups at both ends and contains [(CH2=CH)(CH3)Si-O] and [(CH3)2Si-O] links in the molecular chain, and the ratio of the number of [(CH2=CH)(CH3)Si-O] links to the number of [(CH3)2Si-O] links is 0.5 to 5:100;

[0025] The alkoxy-terminated polydimethylsiloxane has the structure shown in formula (1):

[0026] (R 1 O)2(R 2 )Si-O-[(CH3)2SiO] n -Si(OR 1 )2(R 3 (1)

[0027] Among them, R 1 R 2 and R 3 R is a monovalent hydrocarbon group that is either substituted or unsubstituted. 1 R 2 and R 3 Whether they are the same or different, n is an integer between 100 and 1500.

[0028] In some embodiments, the heat and moisture dual-curing silicone sealant comprises, by weight, the following raw material components:

[0029]

[0030] In some embodiments, the ratio of the number of [(CH2=CH)(CH3)Si-O] chain segments to the number of [(CH3)2Si-O] chain segments is 2 to 5:100.

[0031] In some embodiments, the ratio of the number of [(CH2=CH)(CH3)Si-O] chain segments to the number of [(CH3)2Si-O] chain segments is 2 to 4:100.

[0032] The ratio of the number of [(CH2=CH)(CH3)Si-O] chain segments to the number of [(CH3)2Si-O] chain segments is 2 to 3.6:100.

[0033] In some embodiments, R in equation (1) 1 R 2 and R 3 Each is independently selected from methyl or vinyl.

[0034] In some embodiments, R in equation (1) 1 It is methyl, R 2 and R 3 It is vinyl.

[0035] In some embodiments, n in equation (1) is selected from an integer between 400 and 1000.

[0036] In some embodiments, n in equation (1) is selected from an integer between 550 and 1000.

[0037] In some embodiments, the kinematic viscosity of the hydroxyl-terminated methyl vinyl polysiloxane at 25°C is 20 Pa·s to 80 Pa·s.

[0038] In some embodiments, the alkoxy-terminated polydimethylsiloxane has a kinematic viscosity of 1 Pa·s to 80 Pa·s at 25°C.

[0039] In some embodiments, the crosslinking agent is a mixture of alkoxysilane or its oligomer and hydrogen-containing polysiloxane, and the weight ratio of alkoxysilane or its oligomer to hydrogen-containing polysiloxane is 0.1 to 1:1.

[0040] In some embodiments, the weight ratio of the alkoxysilane or its oligomer to the hydrogen-containing polysiloxane is 0.4 to 0.7:1.

[0041] In some embodiments, the weight ratio of the alkoxysilane or its oligomer to the hydrogen-containing polysiloxane is 0.4 to 0.5:1.

[0042] In some embodiments, the alkoxysilane is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, dimethyldimethoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylvinyldimethoxysilane, 1,2-di(triethoxysilyl)ethane, and 1,2-di(trimethoxysilyl)ethane.

[0043] In some embodiments, the hydrogen-containing polysiloxane is a terminally hydrogen-containing polysiloxane or a side-containing hydrogen-containing polysiloxane, and the hydrogen content of the hydrogen-containing polysiloxane is 1 mmol / g to 10 mmol / g.

[0044] In some embodiments, the hydrogen content of the hydrogen-containing polysiloxane is 3 mmol / g to 6 mmol / g.

[0045] In some embodiments, the catalyst is a mixture of titanate complex and platinum catalyst, and the weight ratio of titanate complex to platinum catalyst is 1 to 6:1.

[0046] In some embodiments, the weight ratio of the titanate complex to the platinum catalyst is 4 to 6:1.

[0047] In some embodiments, the titanate complex is selected from at least one of the following: ethyl acetoacetate chelate of isopropyl titanate, acetylacetone chelate of isopropyl titanate, citrate chelate of isopropyl titanate, ethyl acetoacetate chelate of tert-butyl titanate, acetylacetone chelate of tert-butyl titanate, or citrate chelate of tert-butyl titanate.

[0048] In some embodiments, the platinum catalyst is at least one of the following: a complex of (1,5-cyclooctadiene)platinum chloride and 1-ethynylcyclohexanol; a complex of (1,5-cyclooctadiene)platinum chloride and phenylacetylene; a complex of (1,5-cyclooctadiene)platinum chloride and 3-phenyl-2-propyn-1-ol; a complex of bis(triphenylphosphine)platinum chloride and 1-ethynylcyclohexanol; a complex of bis(triphenylphosphine)platinum chloride and phenylacetylene; a complex of bis(triphenylphosphine)platinum chloride and 3-phenyl-2-propyn-1-ol; a complex of chloroplatinic acid and 1-ethynylcyclohexanol; and a complex of chloroplatinic acid and 3-phenyl-2-propyn-1-ol; the platinum content of the platinum catalyst is 500 ppm to 3000 ppm.

[0049] In some embodiments, the platinum catalyst has a platinum content of 800 ppm to 2500 ppm.

[0050] In some embodiments, the platinum catalyst has a platinum content of 800 ppm to 1000 ppm.

[0051] In some embodiments, the active nano-calcium carbonate has an average particle size of 20 nm to 80 nm and a BET specific surface area of ​​15 m². 2 / g~25m 2 / g.

[0052] In some embodiments, the fumed silica has a BET specific surface area of ​​100 m². 2 / g~400m 2 / g.

[0053] In some embodiments, the tackifier is vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinyltris(isopropyloxy)silane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methylpropoxypropyltrimethoxysilane, etc. One or more of the following: methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, hexamethyldisilazane, N,N-diethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltriethoxysilane, 3-(1,3-dimethylbutene)aminopropyltriethoxysilane, 3-carboxypropyltriethoxysilane, and 3-(3-carboxyallylamino)propyltriethoxysilane.

[0054] In other embodiments of the present invention, a method for preparing the above-mentioned heat and moisture dual-curing silicone sealant is disclosed, comprising the following steps:

[0055] (1) Hydroxyl-terminated methyl vinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano calcium carbonate and fumed silica are vacuum dehydrated at 110℃~130℃ for 120 minutes~180 minutes and cooled under nitrogen protection to obtain the base material.

[0056] (2) At room temperature, the base material obtained in step (1) is stirred under vacuum with crosslinking agent, catalyst and thickener for 40 to 60 minutes.

[0057] The present invention will be described in detail below with reference to specific embodiments.

[0058] Example 1

[0059] The heat and moisture dual-curing silicone sealant of this embodiment includes the following preparation materials (by weight) and steps:

[0060] 1. 100 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 20 Pa·s at 25°C, with a ratio of [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments of 2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 20 parts of alkoxy-terminated polydimethylsiloxane with the structure of formula (2) (kinematic viscosity of 20 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), and 144 parts of polydimethylsiloxane with an average particle size of 40 nm and a BET specific surface area of ​​approximately 20 m² were prepared. 2 / g of nano-calcium carbonate, and 8 parts of BET with a specific surface area of ​​180m² 2 / g of fumed silica was added to a vacuum kneader, heated to 115℃, and vacuum (-0.085MPa) for dehydration and mixing for 120 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0061] (CH3O)2(CH3)Si-O-[(CH3)2SiO] 1000 -Si(OCH3)2(CH3)(2)

[0062] 2. At room temperature, the base material obtained above is placed in a high-speed dispersing mixer, and 11 parts of crosslinking agent (including 4.2 parts of methyltrimethoxysilane and 6.8 parts of side-containing hydrogen polysiloxane with a hydrogen content of 3.6 mmol / g), 0.84 parts of catalyst (including 0.56 parts of ethyl acetoacetate chelate of isopropyl titanate and 0.28 parts of (1,5-cyclooctadiene)platinum chloride and 1-ethynylcyclohexanol complex with a platinum content of 3000 ppm) and 1.45 parts of tackifier (including 1 part of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.45 parts of isocyanate propyltriethoxysilane) are added. The mixture is stirred under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0063] Example 2

[0064] The heat and moisture dual-curing silicone sealant of this embodiment includes the following preparation materials (by weight) and steps:

[0065] 1. 100 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 50 Pa·s at 25°C, kinematic viscosity of 4.2:100, [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments in the molecular chain, purchased from Guangzhou Fuze New Materials Co., Ltd.), 50 parts of alkoxy-terminated polydimethylsiloxane with the structure of formula (2) (kinematic viscosity of 20 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), and 150 parts of an average particle size of 30 nm and a BET specific surface area of ​​approximately 22.5 m² were prepared. 2 / g of nano-calcium carbonate, and 5 parts of BET with a specific surface area of ​​220m² 2 / g of fumed silica was added to a vacuum kneader, heated to 125℃, and vacuum (-0.085MPa) for dehydration and mixing for 110 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0066] 2. At room temperature, place the base material obtained above into a high-speed dispersing mixer, add 16 parts of crosslinking agent (including 3 parts of vinyltrimethoxysilane, 3 parts of methyltrimethoxyalkylsilane and 10 parts of side-containing hydrogen polysiloxane with a hydrogen content of 5.5 mmol / g), 1.09 parts of catalyst (including 0.84 parts of acetylacetone chelate of isopropyl titanate and 0.25 parts of bis(triphenylphosphine)platinum chloride and 1-ethynylcyclohexanol complex with a platinum content of 2500 ppm), and 3.0 parts of tackifier (including 1.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 parts of 3-methacryloyloxypropyltrimethoxysilane), and stir under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0067] Example 3

[0068] The heat and moisture dual-curing silicone sealant of this embodiment includes the following preparation materials (by weight) and steps:

[0069] 1. 100 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 80 Pa·s at 25°C, kinematic viscosity of 4.8:100, [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments in the molecular chain, purchased from Guangzhou Fuze New Materials Co., Ltd.), 30 parts of alkoxy-terminated polydimethylsiloxane with the structure of formula (3) (kinematic viscosity of 1.5 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), and 118 parts of polydimethylsiloxane with an average particle size of 30 nm and a BET specific surface area of ​​approximately 22.5 m² were prepared. 2 / g of nano-calcium carbonate, and 12 parts of BET with a specific surface area of ​​150m² 2 / g of fumed silica was added to a vacuum kneader, heated to 120℃, and vacuum (-0.085MPa) for dehydration and mixing for 150 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0070] (CH3O)2(CH3)Si-O-[(CH3)2SiO] 350 -Si(OCH3)2(CH3)(3)

[0071] 2. At room temperature, the base material obtained above is placed in a high-speed dispersing mixer, and 18 parts of crosslinking agent (including 2 parts of vinyltrimethoxysilane, 3.2 parts of methyltrimethoxyalkylsilane and 12.8 parts of side-containing hydrogen polysiloxane with a hydrogen content of 1.8 mmol / g), 1.6 parts of catalyst (including 1.3 parts of citrate chelate of tert-butyl titanate and 0.3 parts of complex of (1,5-cyclooctadiene)platinum chloride and 3-phenyl-2-propyn-1-ol with a platinum content of 3000 ppm), and 2.0 parts of tackifier (including 1.05 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.45 parts of hexamethyldisilazane and 0.5 parts of 3-methacryloyloxypropyltrimethoxysilane) are added. The mixture is stirred under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0072] Example 4

[0073] The heat and moisture dual-curing silicone sealant of this embodiment includes the following preparation materials (by weight) and steps:

[0074] 1. 100 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 20 Pa·s at 25°C, kinematic viscosity of 3.6:100, [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments in the molecular chain, purchased from Guangzhou Fuze New Materials Co., Ltd.), 20 parts of alkoxy-terminated polydimethylsiloxane with the structure of formula (4) (kinematic viscosity of 5 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), and 120 parts of polydimethylsiloxane with an average particle size of 25 nm and a BET specific surface area of ​​approximately 25 m² were prepared. 2 / g of nano-calcium carbonate, and 10 parts of BET with a specific surface area of ​​180m² 2 / g of fumed silica was added to a vacuum kneader, heated to 125℃, and vacuum (-0.085MPa) for dehydration and mixing for 150 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0075] (CH3O)2(CH=CH2)SiO-[(CH3)2SiO] 550 -Si(OCH3)2(CH=CH2) (4)

[0076] 2. At room temperature, place the base material obtained above into a high-speed dispersing mixer, add 18 parts of crosslinking agent (including 1 part of vinyltrimethoxysilane, 3.35 parts of methyltrimethoxyalkylsilane, 1.65 parts of methylvinyldimethoxysilane, 6 parts of side-containing hydrogen polysiloxane with a hydrogen content of 3.6 mmol / g and 6 parts of side-containing hydrogen polysiloxane with a hydrogen content of 5.5 mmol / g), and 3.5 parts of catalyst (including 3 parts of citrate chelate of isopropyl titanate). The silicone sealant was prepared by mixing the following ingredients with 0.5 parts of a complex of (1,5-cyclooctadiene)platinum chloride and 1-ethynylcyclohexanol (1000 ppm platinum content) and 4.0 parts of a tackifier (including 2.5 parts of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 0.5 parts of isocyanate propyltriethoxysilane and 1 part of 3-methacryloyloxypropyltrimethoxysilane) under vacuum (-0.085 MPa) for 60 minutes.

[0077] Example 5

[0078] The heat and moisture dual-curing silicone sealant of this embodiment includes the following preparation materials (by weight) and steps:

[0079] 1. 100 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 50 Pa·s at 25°C, kinematic viscosity of 4.2:100, [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments, purchased from Guangzhou Fuze New Materials Co., Ltd.), 25 parts of alkoxy-terminated polydimethylsiloxane with the structure of formula (4) (kinematic viscosity of 5 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), and 50 parts of polydimethylsiloxane with an average particle size of 25 nm and a BET specific surface area of ​​approximately 25 m² were prepared. 2 / g of nano-calcium carbonate, and 20 parts of BET with a specific surface area of ​​300m² 2 / g of fumed silica was added to a vacuum kneader, heated to 120℃, and vacuum (-0.085MPa) for dehydration and mixing for 150 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0080] 2. At room temperature, place the base material obtained above into a high-speed dispersing mixer, add 12.68 parts of crosslinking agent (including 3.08 parts of oligomer of methyltrimethylsilane and 1.6 parts of propyltrimethoxysilane, 2 parts of side-hydrogen-containing polysiloxane with a hydrogen content of 1.8 mmol / g and 6 parts of end-hydrogen-containing polysiloxane with a hydrogen content of 3.5 mmol / g), 2.83 parts of catalyst (including 2.33 parts of ethyl acetoacetate chelate of titanate tert-butyl ester and 0.5 parts of complex of bis(triphenylphosphine)platinum chloride with a platinum content of 2500 ppm and 1-ethynylcyclohexanol), and 2.0 parts of tackifier (including 1.5 parts of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 0.5 parts of N,N-diethyl-3-aminopropyltrimethoxysilane), and stir under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0081] Example 6

[0082] The heat and moisture dual-curing silicone sealant of this embodiment includes the following preparation materials (by weight) and steps:

[0083] 1. 100 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 20 Pa·s at 25°C, with a ratio of [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments of 2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 25 parts of alkoxy-terminated polydimethylsiloxane with structure as shown in formula (2) (kinematic viscosity of 20 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), 25 parts of alkoxy-terminated polydimethylsiloxane with structure as shown in formula (4) (kinematic viscosity of 5 Pa·s at 25°C, purchased from Chengtian New Materials Guangzhou Co., Ltd.), and 120 parts of polydimethylsiloxane with an average particle size of 40 nm and a BET specific surface area of ​​approximately 20 m² were used. 2 / g of nano-calcium carbonate, and 15 parts of BET with a specific surface area of ​​200m² 2 / g of fumed silica was added to a vacuum kneader, heated to 120℃, and vacuum (-0.085MPa) for dehydration and mixing for 160 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0084] 2. At room temperature, place the base material obtained above into a high-speed dispersing mixer, add 10.96 parts of crosslinking agent (including 1.92 parts of methyltrimethoxysilane, 1.44 parts of methylvinyldimethoxysilane and 7.6 parts of hydrogen-terminated polysiloxane with a hydrogen content of 3.5 mmol / g), 3 parts of catalyst (including 1.82 parts of ethyl acetoacetate chelate of tert-butyl titanate and 1.18 parts of a complex of (1,5-cyclooctadiene)platinum chloride and 3-phenyl-2-propyn-1-ol with a platinum content of 800 ppm), and 2.2 parts of tackifier (including 1.2 parts of vinyltris(isoallyloxy)silane, 0.25 parts of 1,3,5-tris(trimethoxysilylpropyl)isocyanurate and 0.75 parts of 3-carboxypropyltriethoxysilane), and stir under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0085] Comparative Example 1

[0086] The preparation method of the silicone sealant in this comparative example is the same as that in Example 1, except that 100 parts of hydroxyl-terminated methyl vinyl polysiloxane are replaced with 100 parts of hydroxyl-terminated polydimethylsiloxane (kinematic viscosity of 20 Pa·s at 25°C).

[0087] Comparative Example 2

[0088] This comparative example of a heat and moisture dual-curing silicone sealant includes the following preparation materials (by weight) and steps:

[0089] 1. Same as Example 2;

[0090] 2. At room temperature, place the base material obtained above into a high-speed dispersing mixer, add 16 parts of crosslinking agent (including 8 parts of vinyltrimethoxysilane and 8 parts of methyltrimethoxyalkylsilane), 1.09 parts of catalyst (acetylacetone chelate of isopropyl titanate), and 3.0 parts of tackifier (including 1.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 parts of 3-methacryloyloxypropyltrimethoxysilane), and stir under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0091] Comparative Example 3

[0092] This comparative example of a heat and moisture dual-curing silicone sealant includes the following preparation materials (by weight) and steps:

[0093] 1. 150 parts of hydroxyl-terminated methyl vinyl polysiloxane (kinematic viscosity of 50 Pa·s at 25℃, ratio of [(CH2=CH)(CH3)Si-O] chain segments to [(CH3)2Si-O] chain segments in the molecular chain of 4.2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), with an average particle size of 30 nm and a BET specific surface area of ​​approximately 22.5 m², were used. 2 / g of nano-calcium carbonate, and 5 parts of BET with a specific surface area of ​​220m² 2 / g of fumed silica was added to a vacuum kneader, heated to 125℃, and vacuum (-0.085MPa) for dehydration and mixing for 140 minutes. The mixture was then cooled under nitrogen protection to obtain the base material.

[0094] 2. At room temperature, place the base material obtained above into a high-speed dispersing mixer, add 16 parts of crosslinking agent (hydrogen-containing polysiloxane with a hydrogen content of 5.5 mmol / g), 1.09 parts of catalyst (a complex of bis(triphenylphosphine)platinum chloride and 1-ethynylcyclohexanol with a content of 2500 ppm), and 3.0 parts of tackifier (including 1.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 parts of 3-methacryloyloxypropyltrimethoxysilane), and stir under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0095] Comparative Example 4

[0096] The preparation method of the silicone sealant in this comparative example is the same as that in Example 2, except that 0.25 parts of the complex of bis(triphenylphosphine)platinum chloride with a platinum content of 2500 ppm and 1-ethynylcyclohexanol are replaced with 0.25 parts of the platinum complex of 1,3-divinyltetramethyldisiloxane with a platinum content of 2500 ppm.

[0097] Comparative Example 5

[0098] The preparation method of the silicone sealant in this comparative example is the same as that in Example 2, except that 100 parts of hydroxyl-terminated methyl vinyl polysiloxane are replaced with 100 parts of vinyl-terminated polydimethylsiloxane (kinematic viscosity of 20 Pa·s at 25°C).

[0099] Comparative Example 6

[0100] The preparation method of the silicone sealant in this comparative example is the same as that in Example 2, except that no tackifier is added.

[0101] The silicone sealants prepared in Examples 1-6 and Comparative Examples 1-6 were used to prepare various samples according to the requirements in Table 1. The samples were tested for Shore hardness according to GB / T 531.1-2008, and for tensile strength and elongation at break according to GB / T 528-2009.

[0102] The initial tack, adhesion and adhesion after high temperature aging of the silicone sealant were evaluated by shear test specimens (the substrate being aluminum) in accordance with GB / T 7124-2008.

[0103] Storage period: The prepared silicone sealant was placed in a plastic bottle and sealed at room temperature. The sealant was squeezed out every 15 days, and the storage days when the sealant gelled were recorded.

[0104] Table 1 Curing and maintenance conditions for silicone sealant samples

[0105]

[0106] The performance test results of the silicone sealant are shown in Tables 2 and 3.

[0107] Table 2 Performance of silicone sealants in Examples 1-6

[0108]

[0109]

[0110] Table 3 shows the performance of the silicone sealants in Comparative Examples 1–6.

[0111]

[0112] The heat and moisture dual-curing silicone sealants prepared in Examples 1-6 exhibit dual-curing characteristics. Curing at 130°C for 15 minutes forms a pre-cured elastomer with certain strength and initial tack. The strength and initial tack of this elastomer meet the requirements for rapid positioning of the workpiece in the early stages. Placing the pre-cured sealant at 25°C / 55% humidity for 24 hours further cures it into a high-strength elastomer. After aging at 250°C / 168 hours, the shear strength retention rate of the silicone sealants in Examples 1-6 is all above 80%, indicating excellent temperature resistance. Furthermore, the silicone sealants in Examples 1-6 have a long shelf life at room temperature, exceeding 180 days. The silicone sealants in Examples 4 and 6 exhibit even better overall performance.

[0113] Comparative Example 1 used a hydroxyl-terminated polydimethylsiloxane with the same viscosity as in Example 1 as the base polymer. Because its molecular chain structure does not contain [(CH2=CH)(CH3)Si-O] segments, it cannot undergo an addition reaction with the hydrogen-containing polysiloxane in the system. After curing at 130°C for 15 minutes, it could not form a pre-cured elastomer with strength and initial tack, failing to meet the requirements for rapid positioning. After being placed at 25°C / 55% for 24 hours, it exhibited certain strength and adhesion through condensation crosslinking, but its tensile strength and shear strength were significantly lower than the silicone sealant of Example 1. Furthermore, the shear strength decreased significantly after high-temperature aging, indicating poor adhesion and temperature resistance.

[0114] Compared with Example 2, Comparative Example 2 did not add a crosslinking agent, hydrogen-containing polysiloxane, or a platinum catalyst. Due to the lack of crosslinkable hydrogen-containing components, the sealant could not be pre-cured through an addition reaction after curing at 130°C for 15 minutes. It also could not form a pre-cured elastomer with strength and initial tack. Furthermore, its tensile strength, shear strength, and shear strength after high-temperature aging after being placed at 25°C / 55% for 24 hours were significantly lower than those of Example 2.

[0115] Compared with Example 2, Comparative Example 3 did not add alkoxy-terminated polydimethylsiloxane with the structure of formula (2), nor did it add alkoxysilane crosslinking agent and titanate catalyst. After curing at 130°C for 15 min, it could form a pre-cured elastomer with strength and initial tack. After being placed at 25°C / 55% for 24 h, its shear strength was also improved to a certain extent. However, since it could not be further cured by the hydrolysis and condensation of alkoxysilane, its tensile strength and shear strength were significantly lower than those of Example 2, and its shear strength after high-temperature aging was also significantly lower than that of Example 2.

[0116] Compared to Example 2, Comparative Example 4, using the same platinum content of caster catalyst (1,3-divinyltetramethyldisiloxane platinum complex), could also be pre-cured into an elastomer with certain strength and initial tack after curing at 130°C for 15 minutes. However, because the catalytic activity of caster catalysts commonly used in addition-type systems at high temperatures is not as good as the special platinum catalyst used in this invention, the pre-curing degree of Comparative Example 4 was not high, and its initial tack was much lower than that of Example 2. The bonding failure mode also changed to mixed failure, and the shear strength after being placed at 25°C / 55% for 24 hours and after high-temperature aging was also significantly affected. In addition, the shelf life of the silicone sealant was greatly reduced, and gelation occurred after 30 days of storage at room temperature.

[0117] Comparative Example 5 did not use hydroxyl-terminated methyl vinyl polysiloxane, but instead used vinyl-terminated polydimethylsiloxane of the same viscosity as the base polymer. After curing at 130°C for 15 minutes, although it could be pre-cured via hydrosilylation, its initial tack was poor and could not meet the requirements for rapid positioning. Furthermore, because the vinyl-terminated polydimethylsiloxane molecular chain lacked silanol groups, it could not form further crosslinks with alkoxysilanes and alkoxy-terminated polydimethylsiloxanes through condensation reactions during 24 hours at 25°C / 55%. Therefore, its tensile strength, adhesion, and temperature resistance were significantly lower than those of Example 2. This indicates that simply combining the two curing systems cannot achieve the simultaneous requirements of rapid positioning and rapid curing, high strength, good adhesion, and excellent temperature resistance of this invention.

[0118] The adhesive compound obtained in Comparative Example 6 had similar physical properties to that of Example 2, but due to the absence of a tackifier, it could not form a good bond with the groups on the substrate surface through alkoxy groups, and therefore lacked adhesive strength. Furthermore, the activity of the platinum catalyst at room temperature could not be further suppressed due to the lack of a tackifier, resulting in a significant decrease in the shelf life of the adhesive compound.

[0119] Therefore, it is evident that only by combining hydroxyl-terminated methyl vinyl polysiloxane and alkoxy-terminated polydimethylsiloxane as the base polymer, and adding a mixture of alkoxysilane or its oligomers and hydrogen-containing polysiloxane as a crosslinking agent, a mixture of titanate complex and a specific type of platinum catalyst as a catalyst, and adding an appropriate amount of tackifier, can a single-component silicone sealant be produced through the synergistic effect of all components. This silicone sealant possesses the characteristics of dual curing by heat and moisture. Through short-time heating and pre-curing, a certain strength and initial tack are formed to meet the needs of rapid positioning. Subsequently, the sealant comes into contact with moisture in the air for further condensation, crosslinking, and curing, ultimately yielding an elastomer with high strength, good adhesion, excellent temperature resistance, and a long shelf life, which can be used in various occasions requiring rapid assembly.

[0120] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A silicone sealant that undergoes both heat and moisture curing, characterized in that, By weight, it includes the following raw material components: The hydroxyl-terminated methyl vinyl polysiloxane is a polysiloxane whose molecular chain contains hydroxyl groups at both ends and contains [(CH2=CH)(CH3)Si-O] and [(CH3)2Si-O] links in the molecular chain, and the ratio of the number of [(CH2=CH)(CH3)Si-O] links to the number of [(CH3)2Si-O] links is 0.5 to 5:100; The alkoxy-terminated polydimethylsiloxane has the structure shown in formula (1): (R 1 O)2(R 2 )Si-O-[(CH3)2SiO] n -Si(OR 1 )2(R 3 )(1) Among them, R 1 R 2 and R 3 R is a monovalent hydrocarbon group that is either substituted or unsubstituted. 1 R 2 and R 3 Same or different, n is selected from an integer between 100 and 1500; The crosslinking agent is a mixture of alkoxysilane or its oligomer and hydrogen-containing polysiloxane in a weight ratio of 0.1 to 1:

1. The catalyst is a mixture of titanate complex and platinum catalyst in a weight ratio of 1 to 6:1; the platinum catalyst is a complex of (1,5-cyclooctadiene)platinum chloride and 1-ethynylcyclohexanol, a complex of (1,5-cyclooctadiene)platinum chloride and 3-phenyl-2-propyn-1-ol, or a complex of bis(triphenylphosphine)platinum chloride and 1-ethynylcyclohexanol.

2. The organosilicon sealant with dual heat and moisture curing according to claim 1, characterized in that, Includes the following raw material components:

3. The organosilicon sealant with dual heat and moisture curing according to claim 1 or 2, characterized in that, The ratio of the number of [(CH2=CH)(CH3)Si-O] chain segments to the number of [(CH3)2Si-O] chain segments is 2 to 5:

100.

4. The organosilicon sealant with dual heat and moisture curing according to claim 3, characterized in that, The ratio of the number of [(CH2=CH)(CH3)Si-O] chain segments to the number of [(CH3)2Si-O] chain segments is 2 to 4:

100.

5. The organosilicon sealant with dual heat and moisture curing according to claim 4, characterized in that, The ratio of the number of [(CH2=CH)(CH3)Si-O] chain segments to the number of [(CH3)2Si-O] chain segments is 2 to 3.6:

100.

6. The organosilicon sealant with dual heat and moisture curing according to claim 1 or 2, characterized in that, In the formula (1), R 1 R 2 and R 3 Each is independently selected from methyl or vinyl.

7. The organosilicon sealant with dual heat and moisture curing according to claim 6, characterized in that, In the formula (1), R 1 R 2 and R 3 All are methyl, or R 1 It is methyl, R 2 and R 3 Both are vinyl.

8. The organosilicon sealant with dual heat and moisture curing according to claim 1 or 2, characterized in that, In the formula (1), n ​​is selected from integers between 400 and 1000.

9. The organosilicon sealant with dual heat and moisture curing according to claim 8, characterized in that, In the formula (1), n ​​is selected from integers between 550 and 1000.

10. The organosilicon sealant with dual heat and moisture curing according to claim 1 or 2, characterized in that, The kinematic viscosity of the hydroxyl-terminated methyl vinyl polysiloxane at 25°C is 20 Pa·s to 80 Pa·s. And / or, the kinematic viscosity of the alkoxy-terminated polydimethylsiloxane at 25°C is 1 Pa·s to 80 Pa·s.

11. The organosilicon sealant with dual heat and moisture curing according to claim 1 or 2, characterized in that, The weight ratio of the alkoxysilane or its oligomer to the hydrogen-containing polysiloxane is 0.4 to 0.7:1; And / or, the weight ratio of the titanate complex to the platinum catalyst is 4 to 6:1; And / or, the average particle size of the active nano-calcium carbonate is 20nm to 80nm, and its BET specific surface area is 15m². 2 / g~25m 2 / g; And / or, the BET specific surface area of ​​the fumed silica is 100 m². 2 / g~400m 2 / g; And / or, the tackifier is vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltri(isopropoxy)silane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxy One or more of the following: propylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, propyltrimethoxysilane isocyanate, propyltriethoxysilane isocyanate, 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, hexamethyldisilazane, N,N-diethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltriethoxysilane, 3-(1,3-dimethylbutene)aminopropyltriethoxysilane, 3-carboxypropyltriethoxysilane, and 3-(3-carboxyallylamino)propyltriethoxysilane.

12. The organosilicon sealant with dual heat and moisture curing according to claim 11, characterized in that, The weight ratio of the alkoxysilane or its oligomer to the hydrogen-containing polysiloxane is 0.4 to 0.5:1, and the alkoxysilane is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, dimethyldimethoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylvinyldimethoxysilane, 1,2-di(triethoxysilyl)ethane, and 1,2-di(trimethoxysilyl)ethane. And / or, the hydrogen-containing polysiloxane is a terminally hydrogen-containing polysiloxane or a side-containing hydrogen-containing polysiloxane, and the hydrogen content of the hydrogen-containing polysiloxane is 1 mmol / g to 10 mmol / g; And / or, the titanate complex is selected from at least one of the following: ethyl acetoacetate chelate of isopropyl titanate, acetylacetone chelate of isopropyl titanate, citrate chelate of isopropyl titanate, ethyl acetoacetate chelate of tert-butyl titanate, acetylacetone chelate of tert-butyl titanate, or citrate chelate of tert-butyl titanate. And / or, the platinum catalyst has a platinum content of 500ppm to 3000ppm.

13. The organosilicon sealant with dual heat and moisture curing according to claim 12, characterized in that, The hydrogen content of the hydrogen-containing polysiloxane is 3 mmol / g to 6 mmol / g; the platinum content of the platinum catalyst is 800 ppm to 2500 ppm.

14. The organosilicon sealant with dual heat and moisture curing according to claim 13, characterized in that, The platinum catalyst has a platinum content of 800 ppm to 1000 ppm.

15. A method for preparing a heat and moisture dual-curing silicone sealant according to any one of claims 1 to 14, characterized in that, Includes the following steps: (1) Hydroxyl-terminated methyl vinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano calcium carbonate and fumed silica are vacuum dehydrated at 110℃~130℃ for 120 minutes~180 minutes and cooled under nitrogen protection to obtain the base material. (2) At room temperature, the base material obtained in step (1) is stirred under vacuum with crosslinking agent, catalyst and thickener for 40 to 60 minutes.

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