Organosilicon-modified sealant with high water vapor barrier properties and its preparation method

Abstract

This invention relates to the field of high-performance sealant preparation technology, specifically to a silicone-modified sealant with high water vapor barrier properties and its synthesis method. The method involves a two-step addition reaction of vinyl-terminated polydimethylsiloxane, hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polyolefin to synthesize a vinyl-terminated polydimethylsiloxane and polyolefin block polymer. This block polymer is then reacted with branched hydrogen-containing silicone oil to obtain an elastomer. With the addition of fillers and careful adjustment of the component ratios, an elastic sealant is prepared. This sealant achieves the mechanical properties of conventional silicone sealants in a single application while simultaneously exhibiting excellent water vapor barrier properties. Testing shows that the water vapor barrier properties of this sealant can reach 3–8 g / m³. 2 It has water vapor barrier properties comparable to butyl rubber.

Description

Technical Field

[0001] This invention relates to the field of high-performance sealant preparation technology, specifically to an organosilicon-modified sealant with high water vapor barrier properties and its preparation method. Background Technology

[0002] Silicone sealants are a type of silicone product widely used in various industries. They have a wide operating temperature range, typically -60 to 260°C, which is unmatched by other elastomers. Their excellent weather resistance is one of their greatest advantages, and coupled with good electrical properties, high and low temperature resistance, and adhesion, they have become a widely used silicone material.

[0003] Silicone sealants come in two types: single-component and two-component. Single-component room temperature vulcanizing (room temperature vulcanizing) silicone rubber is packaged in a sealed cartridge. It is extruded from the packaging and cured by cross-linking upon contact with moisture in the air. The curing process proceeds from the surface inwards, and the curing speed is relatively slow. The final curing depth depends on the vulcanization system, temperature, and humidity. Two-component room temperature vulcanizing silicone rubber relies primarily on the moisture within the system for curing. It can cure both the surface and the interior simultaneously, eliminating the issue of deep curing.

[0004] Single-component silicone sealants offer excellent non-corrosive adhesion to metals, plastics, ceramics, and glass, and require no primer, making them highly favored by researchers. However, existing silicone sealants, prioritizing mechanical properties, often neglect the issue of water vapor permeation during formulation design. This necessitates a double-sealing process during application, requiring the initial application of butyl sealant to block moisture. For example, the most common photovoltaic module sealing initially used only butyl sealant. However, because butyl sealant is a hot-melt adhesive, it cannot withstand long-term outdoor high and low temperature conditions. Therefore, researchers have proposed a double-sealing concept, applying a layer of silicone sealant over the butyl sealant. The sealing of insulated glass also currently employs a double-sealing process using both butyl sealant and silicone sealant. Summary of the Invention

[0005] To overcome the above-mentioned technical problems, this invention provides an organosilicon-modified sealant with a high water vapor barrier rate. It can ensure the mechanical properties of the final product at high and low temperatures while achieving an excellent water vapor barrier rate. Only one seal is needed to achieve the same water vapor barrier effect as the double-sealing process in the prior art. It is suitable for sealing in the fields of insulating glass, photovoltaic modules and the like.

[0006] The technical solutions to the above technical problems are as follows:

[0007] A silicone-modified sealant with high water vapor barrier properties, exhibiting a water vapor barrier efficiency of 3–8 g / m². 2The SC polymer comprises, by mass fraction, 35-55% SC polymer, 1-5% side-chain hydrogen-containing silicone oil, 0.5-1% inhibitor, and the balance filler; the SC polymer is a block polymer of vinyl-terminated polydimethylsiloxane and polyolefin with a molecular weight of 200-40000, obtained by the addition reaction of vinyl-terminated polydimethylsiloxane, vinyl-terminated polyolefin, and silane-hydrogen-terminated polydimethylsiloxane.

[0008] Furthermore, the inhibitor is an alkynyl alcohol compound.

[0009] Furthermore, the alkynol compound is any one of 3-methyl-1-butyn-3-ol, methylvinylcyclotetrasiloxane, N,N-diallylformamide, or monoethyl maleate.

[0010] Furthermore, the filler is the type of filler used in conventional sealants, typically selected from calcium carbonate, amorphous silica, fumed silica, aluminum hydroxide, molecular sieves, etc.

[0011] Furthermore, the vinyl-terminated polydimethylsiloxane has a viscosity of 400–50000 cps and a vinyl content of 0.015–0.3 mmol / g.

[0012] Furthermore, vinyl-terminated polyolefins are vinyl-terminated polyC4-C6 olefins, including vinyl-terminated polyisobutylene, vinyl-terminated polybutadiene, vinyl-terminated polyisoprene, vinyl-terminated polyhexadiene, and so on.

[0013] Another object of the present invention is to provide a method for preparing such a silicone-modified sealant with high water vapor barrier properties, comprising the following steps:

[0014] 1) Synthesis of SC prepolymer:

[0015] Equimolar amounts of vinyl-terminated polydimethylsiloxane, silane-hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polyolefin were taken and synthesized in two steps. First, vinyl-terminated polydimethylsiloxane and silane-hydrogen-terminated polydimethylsiloxane were added to a reaction vessel, along with 5-10 ppm of chloroplatinic acid casster catalyst. Toluene or xylene was used as the reaction solvent, and the reaction was carried out in a one-pot manner. The reaction temperature was controlled at 80-120°C, and the addition reaction was carried out for 4-6 hours to obtain polydimethylsiloxane with one vinyl end and silane-hydrogen end. Then, vinyl-terminated polyolefin was added, and the addition reaction was continued at the same temperature for 4-6 hours. The solvent was then distilled off under reduced pressure to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polyolefin with a molecular weight of 200-40000, which is the SC prepolymer.

[0016] The specific reaction mechanism is as follows:

[0017]

[0018] 2) The SC prepolymer, side-chain hydrogen-containing silicone oil, and filler obtained in step 1) are placed in a kneader and kneaded at 35-40°C under a vacuum of 0.08-0.1MPa for 10-30 minutes. 5-10 ppm of chloroplatinic acid casster catalyst and alkynyl alcohol inhibitor are added. During the kneading process, an addition reaction occurs under the action of the catalyst to produce an organosilicon modified sealant elastomer with high water vapor barrier rate.

[0019] The specific reaction mechanism is as follows:

[0020]

[0021] The beneficial effects of this invention are:

[0022] This invention prepares a high-performance silicone-modified sealant. It synthesizes a vinyl-terminated polydimethylsiloxane and polyolefin block polymer through a two-step addition reaction of vinyl-terminated polydimethylsiloxane, hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polyolefin. This block polymer is then reacted with branched hydrogen-containing silicone oil to obtain an elastomer. With the addition of fillers and careful adjustment of the component ratios, an elastic sealant is prepared. This sealant achieves the mechanical properties of conventional silicone sealants in a single application, while also exhibiting excellent water vapor barrier properties. Testing shows that the water vapor barrier properties of this sealant can reach 3–8 g / m³. 2 It has water vapor barrier properties comparable to butyl rubber.

[0023] The block combination of organosilicon and polyolefin gives the synthesized elastomer material superior water vapor barrier properties while maintaining its mechanical properties at high and low temperatures, thus expanding the product's application range.

[0024] The present invention will now be described in further detail with reference to specific embodiments. Detailed Implementation

[0025] Example 1:

[0026] 1) Synthesis of SC prepolymer:

[0027] Equimolar amounts of vinyl-terminated polydimethylsiloxane, silane-hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polyisobutylene with a viscosity of 400 cps and a vinyl content of 0.015 mmol / g were taken and synthesized in a two-step process. First, vinyl-terminated and silane-hydrogen-terminated polydimethylsiloxane were added to a reaction vessel, along with 5 ppm of chloroplatinic acid cassellate catalyst. Toluene was used as the reaction solvent, and a one-pot reaction was conducted at 120°C. After 4 hours of addition reaction, polydimethylsiloxane with a vinyl end and a silane end was obtained. Then, vinyl-terminated polyisobutylene was added, and the addition reaction was continued at this temperature for 6 hours. The solvent was then distilled off under reduced pressure to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polyisobutylene with a molecular weight of 6000, which is the SC prepolymer.

[0028] 2) Preheat the kneader to 80°C. Take 35% of the SC prepolymer obtained in step 1), 1% of the side-chain hydrogen-containing silicone oil, 5 ppm of chloroplatinic acid casster catalyst, 0.5% of 3-methyl-1-butyn-3-ol, and the remainder calcium carbonate and put them into the kneader. Knead at 38°C and under a vacuum of 0.08 MPa for 30 minutes. During the kneading process, an addition reaction occurs under the action of the catalyst to produce an organosilicon modified sealant elastomer with high water vapor barrier rate.

[0029] Example 2:

[0030] 1) Synthesis of SC prepolymer:

[0031] Equimolar amounts of vinyl-terminated polydimethylsiloxane, silane-terminated polydimethylsiloxane, and vinyl-terminated polybutadiene, each with a viscosity of 5000 cps and a vinyl content of 0.02 mmol / g, were used for a two-step synthesis. First, vinyl-terminated and silane-terminated polydimethylsiloxanes were added to a reaction vessel along with 5 ppm of chloroplatinic acid cassell catalyst. Xylene was used as the reaction solvent, and a one-pot reaction was conducted at 80°C. After 6 hours of addition reaction, a polydimethylsiloxane with a vinyl end and a silane end was obtained. Vinyl-terminated polybutadiene was then added, and the reaction was continued at this temperature for another 5 hours. The solvent was then distilled off under reduced pressure to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polybutadiene with a molecular weight of 40000, which is the SC prepolymer.

[0032] 2) Preheat the kneader to 85°C. According to the mass fraction, take 40% of the SC prepolymer obtained in step 1), 3% of the side-chain hydrogen-containing silicone oil, 10 ppm of chloroplatinic acid cassiterite catalyst, 1% of methyl vinylcyclotetrasiloxane, and the remainder amorphous silica and put them into the kneader. Knead at 35°C and under a vacuum of 0.09 MPa for 20 minutes. During the kneading process, an addition reaction occurs under the action of the catalyst to produce an organosilicon modified sealant elastomer with high water vapor barrier rate.

[0033] Example 3:

[0034] 1) Synthesis of SC prepolymer:

[0035] Equimolar amounts of vinyl-terminated polydimethylsiloxane, silane-hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polyisoprene with a viscosity of 50,000 cps and a vinyl content of 0.3 mmol / g were taken and synthesized in a two-step process. First, vinyl-terminated and silane-hydrogen-terminated polydimethylsiloxane were added to a reaction vessel, along with 10 ppm of chloroplatinic acid cassell catalyst. Xylene was used as the reaction solvent, and a one-pot reaction was conducted at 100°C. After 6 hours of addition reaction, a polydimethylsiloxane with a vinyl end and a silane end was obtained. Then, vinyl-terminated polyisoprene was added, and the addition reaction was continued at this temperature for another 4 hours. The solvent was then distilled off under reduced pressure to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polyisoprene with a molecular weight of 30,000, which is the SC prepolymer.

[0036] 2) Preheat the kneader to 85°C. Take 55% of the SC prepolymer obtained in step 1), 5% of the side-chain hydrogen-containing silicone oil, 10 ppm of chloroplatinic acid cassiterite catalyst, 0.75% of N,N-diallyl formamide, and the remainder of fumed silica and put them into the kneader. Knead at 35°C and under a vacuum of 0.1 MPa for 10 minutes. During the kneading process, an addition reaction occurs under the action of the catalyst to produce an organosilicon modified sealant elastomer with high water vapor barrier properties.

[0037] Example 4:

[0038] 1) Synthesis of SC prepolymer:

[0039] Equimolar amounts of vinyl-terminated polydimethylsiloxane, silane-hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polyhexadiene, each with a viscosity of 20,000 cps and a vinyl content of 0.1 mmol / g, were used for a two-step synthesis. First, vinyl-terminated and silane-hydrogen-terminated polydimethylsiloxanes were added to a reaction vessel along with 5 ppm of chloroplatinic acid cassellate catalyst. Toluene was used as the reaction solvent, and a one-pot reaction was conducted at 110°C. After 5 hours of addition reaction, a polydimethylsiloxane with a vinyl end and a silane end was obtained. Then, vinyl-terminated polyhexadiene was added, and the reaction was continued at this temperature for another 6 hours. The solvent was then distilled off under reduced pressure to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polyhexadiene with a molecular weight of 20,000, which is the SC prepolymer.

[0040] 2) Preheat the kneader to 82°C. According to the mass fraction, take 45% of the SC prepolymer obtained in step 1), 3% of the side-chain hydrogen-containing silicone oil, 10 ppm of chloroplatinic acid casster catalyst, 0.85% of monoethyl maleate and the balance aluminum hydroxide and put them into the kneader. Knead at 35°C and under a vacuum of 0.1 MPa for 10 minutes. During the kneading process, an addition reaction occurs under the action of the catalyst to produce an organosilicon modified sealant elastomer with high water vapor barrier rate.

[0041] Example 5:

[0042] 1) Synthesis of SC prepolymer:

[0043] Equimolar amounts of vinyl-terminated polydimethylsiloxane, silane-hydrogen-terminated polydimethylsiloxane, and vinyl-terminated polybutadiene with a viscosity of 1000 cps and a vinyl content of 0.05 mmol / g were taken and synthesized in a two-step process. First, vinyl-terminated and silane-hydrogen-terminated polydimethylsiloxane were added to a reaction vessel, along with 5 ppm of chloroplatinic acid cassell catalyst. Toluene was used as the reaction solvent, and a one-pot reaction was conducted at 95°C. After 4 hours of addition reaction, a polydimethylsiloxane with a vinyl end and a silane end was obtained. Then, vinyl-terminated polybutadiene was added, and the addition reaction was continued at this temperature for another 5 hours. The solvent was then distilled off under reduced pressure to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polybutadiene with a molecular weight of 15000, which is the SC prepolymer.

[0044] 2) Preheat the kneader to 80°C. Take 50% of the SC prepolymer obtained in step 1), 3.5% of the side-chain hydrogen-containing silicone oil, 10 ppm of chloroplatinic acid cassiterite catalyst, 0.8% of 3-methyl-1-butyn-3-ol, and the remainder of the mixture of molecular sieve and calcium carbonate, and put it into the kneader. Knead at 37°C and under a vacuum of 0.85 MPa for 15 minutes. During the kneading process, an addition reaction occurs under the action of the catalyst to produce an organosilicon modified sealant elastomer with high water vapor barrier rate.

[0045] Comparative Example 1:

[0046] Hot-melt butyl sealant (PIB butyl sealant) for insulating glass is prepared according to the following method:

[0047] Step 1: Preheat the kneader to 80-90℃. Add 15 parts of butyl rubber and 35 parts of polyisobutylene with a number average molecular weight greater than 20,000 to the preheated kneader and knead. When the rubber temperature in the kneader reaches 110℃, add 15 parts of carbon black, 25 parts of heavy calcium carbonate with an average particle size of 10-25μm, and 10 parts of ethylene propylene diene monomer (EPDM) rubber. Continue kneading under a vacuum of 0.09 MPa for 2 hours.

[0048] Step 2: Extrude the uniform kneaded mixture obtained in Step 1 using a screw extruder, and install a 40-mesh steel wire mesh at the screw outlet to filter impurities and solid particles during extrusion. After packaging the extruded mixture with a silicone-coated packaging film, cool and solidify it in a cylindrical paper drum to obtain hot-melt butyl sealant.

[0049] Comparative Example 2:

[0050] Referring to the technical solution of Example 1 of the Chinese invention patent, authorized announcement number CN111004604B, entitled "Organic Silicone Sealant and its Preparation Method", an organosilicone sealant was prepared.

[0051] The final products of Examples 1-5 and Comparative Examples 1-2 were tested for mechanical properties and water vapor barrier properties. The water vapor barrier property was tested using an infrared water vapor transmission rate tester according to the ASTM F1249-05 international standard. Other performance measurement standards or methods are as follows:

[0052] Tensile strength: GB / T 528;

[0053] Elongation at break: GB / T 528.

[0054] The data is shown in Table 1 below:

[0055] Table 1

[0056]

[0057] As shown in Table 1 above, the silicone-modified sealant prepared by this invention achieves high and low temperature mechanical properties almost on par with silicone sealant, especially in low temperature elongation, which is significantly higher than butyl rubber. Furthermore, its 1mm water vapor barrier value is significantly better than that of silicone sealant. A well-formulated silicone-modified sealant can achieve a water vapor barrier value comparable to butyl rubber.

[0058] Compared to silicone sealants, the silicone-modified sealant synthesized by the method of this invention can ensure the mechanical properties of the final product at high and low temperatures while possessing excellent water vapor barrier efficiency. Only one seal is needed to achieve the same water vapor barrier effect as existing double-seal processes, making it suitable for sealing in fields such as insulated glass and photovoltaic modules.

[0059] In this invention, the hydride ions at the ends of the silane-terminated polydimethylsiloxane first attack the double bonds at the ends of the vinyl-terminated polydimethylsiloxane, achieving an electrophilic addition reaction to obtain a polydimethylsiloxane intermediate with a double bond at one end and silane ions at the other end. The silane ions at the ends of this intermediate provide hydride ions, which attack the double bonds of the vinyl-terminated polyolefin, further achieving an electrophilic addition reaction to obtain a block polymer of vinyl-terminated polydimethylsiloxane and polyolefin. Through the attack of hydride ions on the side chains of the branched hydrogen-containing silicone oil on the double bonds of this block prepolymer, an electrophilic addition reaction is achieved to obtain an elastomer with a regularly arranged structure. This elastomer is then formulated into a finished silicone sealant by adding a properly proportioned filler. Due to the characteristics of olefin electrophilic addition reactions, the product exhibits excellent polymerization activity, thereby accelerating the curing speed and crosslinking density of the final product.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a silicone-modified sealant with high water vapor barrier rate, characterized in that, comprising the following steps: The 1mm water vapor group isolation rate of the sealant is 3-8g / m 2 The sealant only needs one sealing process, and comprises, in terms of mass fraction, 35-55% of SC polymer, 1-5% of side chain hydrogen-containing silicone oil, 0.5-1% of inhibitor and the balance of filler; the SC polymer is a block polymer of vinyl-terminated polydimethylsiloxane and polyolefin with a molecular weight of 200-40000, which is obtained through two-step addition reaction of vinyl-terminated polydimethylsiloxane, silicon-hydrogen-terminated polydimethylsiloxane and vinyl-terminated polyolefin. 1) synthesis of SC prepolymer: taking equal moles of vinyl-terminated polydimethylsiloxane, silicon-hydrogen-terminated polydimethylsiloxane and vinyl-terminated polyolefin, using two-step synthesis, first, adding vinyl-terminated polydimethylsiloxane and silicon-hydrogen-terminated polydimethylsiloxane into a reaction container, adding 5-10 ppm of chloroplatinic acid catalyst, using toluene or xylene as the reaction solvent, using one-pot boiling method, controlling the reaction temperature at 80-120℃, after 4-6h of addition reaction, obtaining polydimethylsiloxane with one end of vinyl and the other end of silicon-hydrogen, then adding vinyl-terminated polyolefin, continuing to heat and add 4-6h, then distilling out the solvent under reduced pressure, obtaining a block polymer of vinyl-terminated polydimethylsiloxane and polyolefin with a molecular weight of 200-40000, which is the SC prepolymer; The specific reaction mechanism is as follows: 2) Preheat the kneader to 80-85℃, according to the formula of the sealant, put the SC prepolymer obtained in step 1), side-chain hydrogen-containing silicone oil and filler into the kneader, and add 5-10 ppm of chloroplatinic acid catalyst and alkyne alcohol inhibitor, knead at 35-40℃ under vacuum degree of 0.08-0.1 MPa for 10-30 min, during the kneading process, addition reaction occurs under the action of the catalyst, and the finished product is a silicone-modified sealant elastomer with high water vapor barrier rate; The specific reaction mechanism is as follows: ， The inhibitor is an alkyne alcohol compound. The alkyne alcohol compound is 3-methyl-1-butyn-3-ol. 。 2. The production method according to claim 1, characterized by, The filler is any one or several of calcium carbonate, amorphous silica, aluminum hydroxide and molecular sieve.

3. The preparation method according to claim 2, characterized in that, The viscosity of the vinyl-terminated polydimethylsiloxane is 400-50000 cps, and the vinyl content in the vinyl-terminated polydimethylsiloxane is 0.015-0.3 mmol / g.

4. The method of claim 1, wherein, The vinyl-terminated polyolefin is vinyl-terminated polyC4-C6 olefin, including but not limited to vinyl-terminated polyisobutylene, vinyl-terminated polybutadiene, vinyl-terminated polyisoprene and vinyl-terminated polyhexadiene.

5. The preparation method according to claim 1, characterized in that, ​ 6. The preparation method according to claim 1, characterized in that, ​

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