Hot and moisture dual-cured organic silicon sealant and preparation method thereof

Abstract

The invention discloses a hot and moisture dual-cured organic silicon sealant and a preparation method thereof. The organic silicon sealant is prepared from the following raw materials: hydroxyl-terminated methyl vinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano calcium carbonate, fumed silica, a cross-linking agent, a catalyst and a tackifier. The organic silicon sealant organically combines the advantages of a condensation type curing system and an addition type curing system, can be quickly positioned and cured, is high in strength, good in adhesion, excellent in temperature resistance and long in storage life after being cured, and can be used for various occasions needing quick positioning and assembling.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic silicon sealants, and more specifically, the present invention relates to a heat-moisture dual-curing organic silicon sealant and a preparation method thereof. Background Art

[0002] Organic silicon sealants can be divided into two categories according to the curing mechanism: condensation type and addition type, and each product has its own characteristics. Condensation type organic silicon sealants are formulated with base polymers, crosslinking agents, catalysts, fillers and additives. The rubber is sealed in a hose or plastic tube. When used, the rubber is extruded and can be vulcanized into an elastomer when it encounters moisture at room temperature. It is very convenient to use and has been widely used in home appliances, automobiles, electronic appliances, machinery and chemical industries. Addition type organic silicon sealants are a type of product based on the addition reaction of silicon and hydrogen. Vinyl-containing polysiloxanes and hydrogen-containing polysiloxanes are crosslinked under the catalysis of platinum complexes to form elastomers. It has the characteristics of no by-products, environmental friendliness, high conversion rate, low shrinkage rate, and easy control of crosslinking density and speed.

[0003] At a time when industrial production is increasingly integrated with informatization and intelligence, conventional one-component condensation-type silicone sealants are facing problems such as long curing time, low strength, and insufficient temperature resistance. The curing speed and adhesion of addition-type silicone sealants are limited by temperature, and usually require higher temperatures and longer heating times to form good adhesion to the substrate. Before the adhesive cures, the workpiece requires additional mechanical fixation and support, which cannot meet the requirements of rapid positioning and assembly. Since the two curing systems use different base polymers, crosslinkers, and catalysts, if the two curing systems are physically mixed, on the one hand, the primary aminosilane or secondary aminosilane added to the condensation system will cause the Custer catalyst used in the addition system to be poisoned and unable to cure, and the requirements of rapid positioning cannot be met; on the other hand, the polymers of the two systems will not undergo crosslinking reactions, and the temperature resistance and strength of the mixture only depend on the proportion of the addition system in the mixture, while the temperature resistance and strength of the condensation system will not be improved due to physical mixing.

[0004] There have been many attempts to combine two or more curing systems in the prior art. For example, the use of acrylic and silicone polymers for composite modification can obtain products with UV and moisture dual curing, which can solve the problem of rapid positioning to a certain extent. However, UV irradiation can only act on the exposed parts of the sealant surface. For the interior of the workpiece or the shadow area that is difficult to cover with UV irradiation, it can only rely on contact with moisture in the air to gradually complete the curing, which is subject to certain limitations in application. In addition, due to the low temperature when the UV moisture dual curing product forms a bond with the substrate, its bonding strength with the substrate is low and its temperature resistance is not high. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a silicone sealant that can simultaneously meet the requirements of rapid positioning and rapid curing, and has high strength, good bonding, excellent temperature resistance and a long storage period.

[0006] The specific technical solutions for achieving the above-mentioned invention objectives include the following.

[0007] In a first aspect of the present invention, a heat-moisture dual-curing silicone sealant is provided, which comprises the following raw material components in parts by weight:

[0008]

[0009] The hydroxyl-terminated methylvinyl polysiloxane has hydroxyl groups at both ends of the molecular chain, and the molecular chain contains [(CH 2 =CH)(CH 3 )Si-O] chain and [(CH 3 ) 2 Si-O] chain segments, and [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 The ratio of Si-O] chain number is 0.5 to 5:100;

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

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

[0012] Among them, R 1 , R 2 and R 3 is a substituted or unsubstituted monovalent hydrocarbon group, R 1 , R 2 and R 3 are the same or different, and n is an integer selected from 100 to 1500.

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

[0014] (1) dehydrating hydroxyl-terminated methylvinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano-calcium carbonate and fumed silica at 110° C. to 130° C. under vacuum for 120 to 180 minutes, and cooling under nitrogen protection to obtain a base material;

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

[0016] In the present invention, hydroxyl-terminated methylvinyl polysiloxane and alkoxy-terminated polydimethylsiloxane are used as base polymers, a mixture of alkoxysilane or its oligomer 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 a tackifier and other ingredients are added to prepare a silicone sealant with heat and moisture dual curing properties. When the silicone sealant is heated to a corresponding temperature (about 130°C), the vinyl group in the hydroxyl-terminated methylvinyl polysiloxane and the hydrogen-containing polysiloxane in the crosslinking agent react with the platinum catalyst to cause an addition reaction, so that the silicone sealant can be pre-cured in a relatively short time (about 15 minutes) to form an elastomer with certain tensile strength, shear strength and initial adhesion to meet the requirements of rapid positioning of the workpiece in the early stage; at the same time, heating pre-curing can also promote the alkoxy group in the tackifier to better combine with the group on the surface of the bonded substrate, thereby improving the bonding strength between the sealant and the substrate. After pre-curing by heating, the elastomer contacts with moisture in the air, and the alkoxysilane or oligomer thereof in the cross-linking agent is hydrolyzed under the catalysis of the titanate complex, and further condenses and cross-links with the hydroxyl groups in the hydroxyl-terminated methylvinyl polysiloxane and the alkoxy groups in the alkoxy-terminated polydimethylsiloxane to complete the curing, thereby increasing the cross-linking density of the sealant, further improving its shear strength, and having excellent heat resistance. After aging at 250°C / 168h, the shear strength retention rate is above 80%. Under the joint action of all the raw material components of the present invention, the organosilicon sealant of the present invention organically combines the advantages of the condensation type and addition type curing systems, can be quickly positioned and cured, and has high strength, good adhesion, and excellent heat resistance after curing, and can be used in various occasions requiring rapid positioning and assembly.

[0017] The equipment required for the heating pre-curing of the organic silicon sealant of the present invention is simple and easy to operate. The pre-curing speed of the sealant is only affected by the temperature, thereby avoiding the problem that UV irradiation cannot cover the interior of the workpiece or the shadow area.

[0018] In addition, the present invention selects the type of platinum catalyst and controls the addition amount thereof, and adds a proper amount of tackifier, so that the polar groups in the tackifier coordinate with the platinum catalyst to a certain extent, thereby inhibiting the catalytic activity of the platinum catalyst at room temperature, so that the heat-moisture dual-curing silicone sealant of the present invention can be packaged in a single-component form, without the need for metering and mixing, thereby improving the convenience of use; and can be stably stored at room temperature with a long storage period, thereby avoiding the problem that the current single-component addition-type silicone sealants usually need to be stored in a refrigerator. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0021] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used can be purchased from commercial channels unless otherwise specified.

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

[0023]

[0024] The hydroxyl-terminated methylvinyl polysiloxane has hydroxyl groups at both ends of the molecular chain, and the molecular chain contains [(CH 2 =CH)(CH 3 )Si-O] chain and [(CH 3 ) 2 Si-O] chain segments, and [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 The ratio of Si-O] chain number is 0.5 to 5:100;

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

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

[0027] Among them, R 1 , R 2 and R 3 is a substituted or unsubstituted monovalent hydrocarbon group, R 1 , R 2 and R 3 are the same or different, and n is an integer selected from 100 to 1500.

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

[0029]

[0030] In some embodiments, the [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 The ratio of the number of Si-O] chain links is 2 to 5:100.

[0031] In some embodiments, the [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 The ratio of the number of Si-O] chain links is 2 to 4:100.

[0032] The [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 The ratio of the number of Si-O] chain links is 2 to 3.6:100.

[0033] In some embodiments, R in the formula (1) 1 , R 2 and R 3 are independently selected from methyl or vinyl.

[0034] In some embodiments, R in the formula (1) 1 is methyl, R 2 and R 3 For vinyl.

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

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

[0037] In some embodiments, the kinematic viscosity of the hydroxyl-terminated methylvinyl 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 0.1-1:1.

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

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

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

[0043] In some embodiments, the hydrogen-containing polysiloxane is a terminal hydrogen-containing polysiloxane or a side 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 of the embodiments, the catalyst is a mixture of a titanate complex and a platinum catalyst, and the weight ratio of the titanate complex to the platinum catalyst is 1 to 6:1.

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

[0047] In some of the embodiments, the titanate complex is selected from at least one of 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 of the embodiments, the platinum catalyst is at least one of 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; and the platinum content of the platinum catalyst is 500ppm to 3000ppm.

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

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

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

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

[0053] In some embodiments, the tackifier is vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy)silane, vinyl tri(isoallyloxy)silane, γ-(2,3-epoxypropoxy)propyl trimethoxysilane, γ-(2,3-epoxypropoxy)propyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-methylacryloxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-methylacryloxypropyl trimethoxysilane, 3-methyl ... One or more of acryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, isocyanatepropyltrimethoxysilane, isocyanatepropyltriethoxysilane, 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, hexamethyldisilazane, N,N-diethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltriethoxysilane, 3-(1,3-dimethylbutylene)aminopropyltriethoxysilane, 3-carboxypropyltriethoxysilane, and 3-(3-carboxyallylamide)propyltriethoxysilane.

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

[0055] (1) dehydrating hydroxyl-terminated methylvinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano-calcium carbonate and fumed silica at 110° C. to 130° C. under vacuum for 120 to 180 minutes, and cooling under nitrogen protection to obtain a base material;

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

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

[0058] Example 1

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

[0060] 1. Add 100 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 20 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2Si-O] chain number ratio is 2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 20 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (2) (kinematic viscosity at 25°C is 20 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 144 parts of an average particle size of 40 nm and a BET specific surface area of ​​about 20 m 2 / g of nano calcium carbonate, and 8 parts of BET specific surface area of ​​180m 2 / g of fumed silica was added into a vacuum kneader, heated to 115°C, vacuum (-0.085MPa) for dehydration and blending for 120 minutes, and cooled under nitrogen protection to obtain a base material;

[0061] (CH 3 O) 2 (CH 3 )Si-O-[(CH 3 ) 2 SiO] 1000 -Si(OCH 3 ) 2 (CH 3 )(2)

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

[0063] Example 2

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

[0065] 1. Add 100 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 50 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2Si-O] chain number ratio is 4.2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 50 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (2) (kinematic viscosity at 25°C is 20 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 150 parts of an average particle size of 30 nm and a BET specific surface area of ​​approximately 22.5 m 2 / g of nano calcium carbonate, and 5 parts of BET specific surface area of ​​220m 2 / g of fumed silica was added into a vacuum kneader, heated to 125°C, vacuum (-0.085MPa) for dehydration and blending for 110 minutes, and cooled under nitrogen protection to obtain a base material;

[0066] 2. At room temperature, the base material obtained above was placed in a high-speed disperser, and 16 parts of a crosslinking agent (including 3 parts of vinyl trimethoxysilane, 3 parts of methyl trimethoxy silane and 10 parts of a side hydrogen-containing polysiloxane with a hydrogen content of 5.5 mmol / g), 1.09 parts of a catalyst (including 0.84 parts of acetylacetone chelate of isopropyl titanate and 0.25 parts of a complex of bis(triphenylphosphine) platinum chloride and 1-ethynylcyclohexanol with a platinum content of 2500 ppm), and 3.0 parts of a tackifier (including 1.5 parts of γ-(2,3-epoxypropoxy)propyl trimethoxy silane and 1.5 parts of 3-methacryloxypropyl trimethoxy silane) were added, and the mixture was stirred under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0067] Example 3

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

[0069] 1. Add 100 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 80 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 Si-O] chain number ratio is 4.8:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 30 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (3) (kinematic viscosity at 25°C is 1.5 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 118 parts of an average particle size of 30 nm and a BET specific surface area of ​​approximately 22.5 m 2 / g of nano calcium carbonate, and 12 parts of BET specific surface area of ​​150m 2 / g of fumed silica was added into a vacuum kneader, heated to 120°C, vacuum (-0.085MPa) for dehydration and blending for 150 minutes, and cooled under nitrogen protection to obtain a base material;

[0070] (CH 3 O) 2 (CH 3 )Si-O-[(CH 3 ) 2 SiO] 350 -Si(OCH 3 ) 2 (CH 3 )(3)

[0071] 2. At room temperature, the base material obtained above was placed in a high-speed disperser, and 18 parts of a crosslinking agent (including 2 parts of vinyl trimethoxysilane, 3.2 parts of methyl trimethoxy silane and 12.8 parts of a side hydrogen-containing polysiloxane with a hydrogen content of 1.8 mmol / g), 1.6 parts of a catalyst (including 1.3 parts of a citrate chelate of tert-butyl titanate and 0.3 parts of a 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 a tackifier (including 1.05 parts of γ-(2,3-epoxypropoxy)propyl trimethoxy silane, 0.45 parts of hexamethyldisilazane and 0.5 parts of 3-methacryloxypropyl trimethoxy silane) were added, and the mixture was stirred under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0072] Example 4

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

[0074] 1. Add 100 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 20 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 Si-O] chain number ratio is 3.6:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 20 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (4) (kinematic viscosity at 25°C is 5 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 120 parts of an average particle size of 25 nm and a BET specific surface area of ​​about 25 m 2 / g of nano calcium carbonate, and 10 parts of BET specific surface area of ​​180m 2 / g of fumed silica was added into a vacuum kneader, heated to 125°C, vacuum (-0.085MPa) for dehydration and blending for 150 minutes, and cooled under nitrogen protection to obtain a base material;

[0075] (CH 3 O) 2 (CH=CH2 )SiO-[(CH 3 ) 2 SiO] 550 -Si(OCH 3 ) 2 (CH=CH 2 ) (4)

[0076] 2. At room temperature, the base material obtained above was placed in a high-speed disperser, and 18 parts of a crosslinking agent (including 1 part of vinyl trimethoxysilane, 3.35 parts of methyl trimethoxy silane, 1.65 parts of methyl vinyl dimethoxy silane, 6 parts of a side hydrogenated polysiloxane with a hydrogen content of 3.6 mmol / g and 6 parts of a side hydrogenated polysiloxane with a hydrogen content of 5.5 mmol / g), 3.5 parts of a catalyst (including 3 parts of a citrate chelate of isopropyl titanate) were added. The organic silicone sealant was prepared by mixing the organic silicone sealant with 0.5 parts of a complex of (1,5-cyclooctadiene) platinum chloride and 1-ethynyl cyclohexanol having a platinum content of 1000 ppm), and 4.0 parts of a tackifier (including 2.5 parts of 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 0.5 parts of isocyanatepropyltriethoxysilane and 1 part of 3-methacryloxypropyltrimethoxysilane), and stirring for 60 minutes under vacuum (-0.085 MPa).

[0077] Example 5

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

[0079] 1. Add 100 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 50 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 Si-O] chain number ratio is 4.2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 25 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (4) (kinematic viscosity at 25°C is 5 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 50 parts of an average particle size of 25 nm and a BET specific surface area of ​​about 25 m 2 / g of nano calcium carbonate, and 20 parts of BET specific surface area of ​​300m 2 / g of fumed silica was added into a vacuum kneader, heated to 120°C, vacuum (-0.085MPa) for dehydration and blending for 150 minutes, and cooled under nitrogen protection to obtain a base material;

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

[0081] Example 6

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

[0083] 1. Add 100 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 20 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2 Si-O] chain ratio is 2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 25 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (2) (kinematic viscosity at 25°C is 20 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 25 parts of alkoxy-terminated polydimethylsiloxane with a structure such as formula (4) (kinematic viscosity at 25°C is 5 Pa·s, purchased from Guangzhou Chengtian New Materials Co., Ltd.), 120 parts of an average particle size of 40 nm and a BET specific surface area of ​​about 20 m 2 / g of nano calcium carbonate, and 15 parts of BET specific surface area of ​​200m 2 / g of fumed silica was added into a vacuum kneader, heated to 120°C, vacuum (-0.085MPa) for dehydration and blending for 160 minutes, and cooled under nitrogen protection to obtain a base material;

[0084] 2. At room temperature, the base material obtained above was placed in a high-speed disperser, and 10.96 parts of a crosslinking agent (including 1.92 parts of methyltrimethoxysilane, 1.44 parts of methylvinyldimethoxysilane and 7.6 parts of terminal hydrogen-containing polysiloxane with a hydrogen content of 3.5 mmol / g), 3 parts of a catalyst (including 1.82 parts of ethyl acetate 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 a tackifier (including 1.2 parts of vinyltri(isoallyloxy)silane, 0.25 parts of 1,3,5-tris(trimethoxysilylpropyl)isocyanurate and 0.75 parts of 3-carboxypropyltriethoxysilane) were added, and the mixture was stirred under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0085] Comparative Example 1

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

[0087] Comparative Example 2

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

[0089] 1. Same as Example 2;

[0090] 2. At room temperature, the base material obtained above was placed in a high-speed disperser, and 16 parts of a crosslinking agent (including 8 parts of vinyltrimethoxysilane and 8 parts of methyltrimethoxysilane), 1.09 parts of a catalyst (acetylacetone chelate of isopropyl titanate), and 3.0 parts of a tackifier (including 1.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 parts of 3-methacryloxypropyltrimethoxysilane) were added, and the mixture was stirred under vacuum (-0.085 MPa) for 60 minutes to obtain the silicone sealant.

[0091] Comparative Example 3

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

[0093] 1. Add 150 parts of hydroxyl-terminated methylvinyl polysiloxane (kinematic viscosity at 25°C is 50 Pa·s, [(CH 2 =CH)(CH 3 )Si-O] chain number and [(CH 3 ) 2The ratio of Si-O] chain number is 4.2:100, purchased from Guangzhou Fuze New Materials Co., Ltd.), 150 parts, the average particle size is 30nm, and the BET specific surface area is about 22.5m 2 / g of nano calcium carbonate, and 5 parts of BET specific surface area of ​​220m 2 / g of fumed silica was added into a vacuum kneader, heated to 125°C, vacuum (-0.085MPa) for dehydration and blending for 140 minutes, and cooled under nitrogen protection to obtain a base material;

[0094] 2. At room temperature, the base material obtained above was placed in a high-speed disperser, and 16 parts of a cross-linking agent (a side hydrogen-containing polysiloxane with a hydrogen content of 5.5 mmol / g), 1.09 parts of a catalyst (a complex of bis(triphenylphosphine)platinum chloride and 1-ethynylcyclohexanol with a content of 2500 ppm), and 3.0 parts of a tackifier (including 1.5 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 parts of 3-methacryloxypropyltrimethoxysilane) were added, and the mixture was stirred 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 and 1-ethynylcyclohexanol with a platinum content of 2500 ppm is replaced by 0.25 parts of 1,3-divinyltetramethyldisiloxane platinum complex 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 methylvinyl polysiloxane are replaced by 100 parts of vinyl-terminated polydimethylsiloxane (with a kinematic viscosity of 20 Pa·s at 25° C.).

[0099] Comparative Example 6

[0100] The preparation method of the organosilicon 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 to 6 and Comparative Examples 1 to 6 were made into various samples according to the requirements of 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 adhesion, adhesion and adhesion after high temperature aging of the silicone sealant were evaluated in the form of shear specimens (the bonding substrate was aluminum) and tested in accordance with GB / T 7124-2008.

[0103] Shelf life: Place the prepared silicone sealant in a plastic bottle and store it in a sealed container at room temperature. Squeeze out the sealant every 15 days and record the number of days it has been stored until gelling occurs.

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

[0105]

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

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

[0108]

[0109]

[0110] Table 3 Performance of silicone sealants of Comparative Examples 1 to 6

[0111]

[0112] The heat-moisture dual-cured silicone sealant prepared in Examples 1 to 6 has the characteristics of dual curing. After curing at 130°C for 15 minutes, a pre-cured elastomer with certain strength and initial adhesion is formed. The strength and initial adhesion of the elastomer can meet the requirements of rapid positioning of the workpiece in the early stage. The pre-cured sealant is placed at 25°C / 55% for 24 hours to further cure into an elastomer with high strength. After aging at 250°C / 168 hours, the shear strength retention rate of the silicone sealants of Examples 1 to 6 is more than 80%, indicating that it has excellent temperature resistance. And the silicone sealants of Examples 1 to 6 have a long storage period at room temperature, all exceeding 180 days. The silicone sealants of Examples 4 and 6 have better comprehensive performance.

[0113] Comparative Example 1 used hydroxyl-terminated polydimethylsiloxane with the same viscosity as Example 1 as the base polymer. Since its molecular chain structure does not contain [(CH 2 =CH)(CH 3)Si-O] chain segments, so it cannot react with the hydrogen-containing polysiloxane in the system. After curing at 130°C for 15 minutes, it cannot form a pre-cured elastomer with strength and initial adhesion, and cannot meet the requirements of rapid positioning. After being placed at 25°C / 55% for 24 hours, it has certain strength and adhesion through condensation cross-linking, but its tensile strength and shear strength are significantly lower than those of the silicone sealant in Example 1, and the shear strength decreases significantly after high-temperature aging, indicating that its adhesion and temperature resistance are poor.

[0114] Compared with Example 2, Comparative Example 2 does not add the crosslinking agent hydrogen-containing polysiloxane and the platinum catalyst. Due to the lack of crosslinkable hydrogen-containing components, after curing at 130°C for 15 minutes, the sealant cannot be pre-cured by addition reaction, and it is also unable to form a pre-cured elastomer with strength and initial adhesion. The tensile strength, shear strength and shear strength after high-temperature aging after being placed at 25°C / 55% for 24 hours are also significantly lower than those in Example 2.

[0115] Compared with Example 2, Comparative Example 3 does not add alkoxy-terminated polydimethylsiloxane of structure such as formula (2), nor does it add alkoxysilane crosslinking agent and titanate catalyst. After curing at 130°C for 15 minutes, a precured elastomer with strength and initial adhesion can be formed, and the shear strength is also improved to a certain extent after being placed at 25°C / 55% for 24 hours. However, since it cannot be further cured by hydrolysis condensation of alkoxysilane, its tensile strength and shear strength are significantly lower than those of Example 2, and the shear strength after high temperature aging is also significantly lower than that of Example 2.

[0116] Compared with Example 2, Comparative Example 4 uses a Custer catalyst (1,3-divinyltetramethyldisiloxane platinum complex) with the same platinum content, and can also be pre-cured into an elastomer with certain strength and initial adhesion after curing at 130°C for 15 minutes. However, since the catalytic activity of the Custer catalyst commonly used in the addition system at high temperature is not as good as the special platinum catalyst used in the present invention, the pre-curing degree of Comparative Example 4 is not high, and its initial adhesion is much lower than that of Example 2. The form of adhesive failure also changes to mixed failure, and the shear strength after being placed at 25°C / 55% for 24 hours and high-temperature aging is also significantly affected. In addition, the storage period of the silicone sealant is greatly reduced, and gel appears after 30 days of storage at room temperature.

[0117] Comparative Example 5 does not use hydroxyl-terminated methylvinyl polysiloxane, but uses vinyl-terminated polydimethylsiloxane with the same viscosity as the base polymer. After curing at 130°C for 15 minutes, although it can be pre-cured by hydrosilylation reaction, its initial adhesion is poor and cannot meet the requirements of rapid positioning. Moreover, due to the lack of silanol groups in the molecular chain of vinyl-terminated polydimethylsiloxane, it cannot be further cross-linked with alkoxysilane and alkoxy-terminated polydimethylsiloxane through condensation reaction during 24 hours at 25°C / 55%, so its tensile strength, adhesion and temperature resistance are significantly lower than those of Example 2. This shows that the two curing systems cannot achieve the requirements of the present invention that can simultaneously meet rapid positioning and rapid curing, high strength, good adhesion and excellent temperature resistance.

[0118] The physical properties of the rubber obtained in Comparative Example 6 are not much different from those in Example 2, but since no tackifier is added, the alkoxy groups cannot form a good bond with the groups on the surface of the substrate, and therefore do not have adhesion. Since there is no tackifier, the activity of the platinum catalyst at room temperature cannot be further inhibited, and therefore, the storage period of the rubber is significantly reduced.

[0119] It can be seen that only by using a combination of hydroxyl-terminated methylvinyl polysiloxane and alkoxy-terminated polydimethylsiloxane as the base polymer, adding a mixture of alkoxysilane or its oligomers and hydrogen-containing polysiloxane as a cross-linking agent, a mixture of titanate complex and a specific type of platinum catalyst as a catalyst, and adding an appropriate amount of tackifier, can the components work synergistically to make a single-component silicone sealant, and the silicone sealant has the characteristics of dual curing by heat and moisture. Through a short period of heating pre-curing, a certain strength and initial adhesion are formed to meet the needs of rapid positioning. Subsequently, the sealant is further condensed and cross-linked and cured in contact with moisture in the air to finally obtain an elastomer with high strength, good adhesion, excellent temperature resistance and long storage period, which can be used in various occasions requiring rapid assembly.

[0120] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A heat and moisture dual curing silicone sealant, characterized in that: In parts by weight, it includes the following raw material components: The hydroxyl-terminated methylvinyl polysiloxane is a polysiloxane having hydroxyl groups at both ends of the molecular chain, containing [(CH2=CH)(CH3)Si-O] segments and [(CH3)2Si-O] segments in the molecular chain, and the ratio of the number of [(CH2=CH)(CH3)Si-O] segments to the number of [(CH3)2Si-O] segments is 0.5 to 5:100; The alkoxy-terminated polydimethylsiloxane has a 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 is a substituted or unsubstituted monovalent hydrocarbon group, R 1 , R 2 and R 3 are the same or different, and n is an integer selected from 100 to 1500.

2. The heat and moisture dual-curing silicone sealant according to claim 1, characterized in that: The raw material components include:

3. The heat and moisture dual-curing silicone sealant 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, preferably 2 to 4:100, and more preferably 2 to 3.6:

100.

4. The heat and moisture dual-curing silicone sealant according to claim 1 or 2, characterized in that: In the formula (1), R 1 , R 2 and R 3 are independently selected from methyl or vinyl.

5. The heat and moisture dual-curing silicone sealant according to claim 4, characterized in that: In the formula (1), R 1 , R 2 and R 3 All are methyl, or R 1 is methyl, R 2 and R 3 All are vinyl.

6. The heat and moisture dual-curing silicone sealant according to claim 1 or 2, characterized in that: In the formula (1), n ​​is selected from an integer between 400 and 1000, and preferably selected from an integer between 550 and 1000.

7. The heat and moisture dual-curing silicone sealant according to claim 1 or 2, characterized in that: The kinematic viscosity of the hydroxyl-terminated methylvinyl polysiloxane at 25° C. is 20 Pa·s to 80 Pa·s; And / or, the alkoxy-terminated polydimethylsiloxane has a kinematic viscosity of 1 Pa·s to 80 Pa·s at 25°C.

8. The heat and moisture dual-curing silicone sealant according to claim 1 or 2, characterized in that: 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, preferably 0.4 to 0.7:1, and more preferably 0.4 to 0.5:1; And / or, the catalyst is a mixture of a titanate complex and a platinum catalyst, and the weight ratio of the titanate complex to the platinum catalyst is 1 to 6:1, preferably 4 to 6:1; And / or, the average particle size of the active nano calcium carbonate is 20nm to 80nm, and the BET specific surface area is 15m 2 / g~25m 2 / g; And / or, the BET specific surface area of ​​the fumed silica is 100 m 2 / g~400m 2 / g; And / or, the tackifier is vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy)silane, vinyl tri(isoallyloxy)silane, γ-(2,3-epoxypropyloxy)propyl trimethoxysilane, γ-(2,3-epoxypropyloxy)propyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, One or more of propylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, isocyanatepropyltrimethoxysilane, isocyanatepropyltriethoxysilane, 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, hexamethyldisilazane, N,N-diethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltriethoxysilane, 3-(1,3-dimethylbutylene)aminopropyltriethoxysilane, 3-carboxypropyltriethoxysilane, and 3-(3-carboxyallylamide)propyltriethoxysilane.

9. The heat and moisture dual-curing silicone sealant according to claim 8, characterized in that: The alkoxysilane is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, dimethyldimethoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylvinyldimethoxysilane, 1,2-bis(triethoxysilyl)ethane, and 1,2-bis(trimethoxysilyl)ethane; And / or, the hydrogen-containing polysiloxane is a terminal hydrogen-containing polysiloxane or a side hydrogen-containing polysiloxane, and the hydrogen content of the hydrogen-containing polysiloxane is 1 mmol / g to 10 mmol / g, preferably 3 mmol / g to 6 mmol / g. And / or, the titanate complex is selected from at least one of an ethyl acetoacetate chelate of isopropyl titanate, an acetylacetone chelate of isopropyl titanate, a citrate chelate of isopropyl titanate, an ethyl acetoacetate chelate of tert-butyl titanate, an acetylacetone chelate of tert-butyl titanate, or a citrate chelate of tert-butyl titanate; And / or, the platinum catalyst is at least one of 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 500ppm to 3000ppm, preferably 800ppm to 2500ppm, and more preferably 800ppm to 1000ppm.

10. A method for preparing the heat-moisture dual-curing silicone sealant according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) dehydrating hydroxyl-terminated methylvinyl polysiloxane, alkoxy-terminated polydimethylsiloxane, active nano-calcium carbonate and fumed silica at 110° C. to 130° C. under vacuum for 120 to 180 minutes, and cooling under nitrogen protection to obtain a base material; (2) At room temperature, the base material obtained in step (1) is stirred with a cross-linking agent, a catalyst and a tackifier under vacuum for 40 to 60 minutes.

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