Background
The single-component silicone sealant is a pasty high polymer material and can be cured into a tough rubber solid when contacting with moisture in the air. The silicone adhesive has the characteristics of strong bonding force, good sealing performance, weather resistance, vibration resistance, moisture resistance, odor resistance and large adaptability to cold and heat changes. In addition, the wide applicability can realize the sealing of most engineering mechanical parts and the bonding between building material products, so the application value is very high
The silicone sealant does not flow under its own weight and can be used over a seam in a roof or sidewall without sagging, slumping or running off. It is mainly used for bonding and sealing of dry and clean metal and glass, most of grease-free wood, silicone resin, vulcanized silicone rubber, ceramics, natural and synthetic fibers, and many painted plastic surfaces. The high-quality silicone adhesive can not be extruded and the physical properties can not be changed when used at the temperature below zero ℃. The fully cured silicone glass adhesive can maintain the strength continuously and effectively when used at 210 ℃.
The silicone adhesive is required to have initial strength and bear certain sealing pressure after being coated for about 30 minutes in the using process, particularly in the flow line operation process in some mechanical fields. Generally, silica gel cannot be rapidly cured in a short time after being coated with glue and has initial strength, and a mechanical assembly line needs to be continuously stopped and intermitted to wait for the curing process of the glue when in use. Therefore, the production continuity is seriously influenced, and the production assembly efficiency of mechanical parts is reduced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the silicone adhesive which can be quickly cured and can be immediately sealed and the preparation method thereof.
An instant sealing silicone adhesive is composed of the following components in percentage by weight: 28-32% of hydroxyl-terminated polydimethylsiloxane (viscosity 20000cp), 20-24% of hydroxyl-terminated polydimethylsiloxane (viscosity 3000cp), 35-40% of nano calcium carbonate, 4.0-6.0% of methyl tributyrinoxime silane, 1.0-2.0% of vinyl tributyrinoxime silane, 3.0-5.0% of fumed silica, 0.03-0.06% of hexamethyldisilazane, 0.03-0.06% of dibutyltin dilaurate and 0.03-0.06% of N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane.
Preferably, the instant sealing silicone adhesive consists of the following components in percentage by weight: 29.5% hydroxy-terminated polydimethylsiloxane (20000 cp viscosity), 21% hydroxy-terminated polydimethylsiloxane (3000cp viscosity), 38.5% nano calcium carbonate, 5.4% methyltributanonoximosilane, 1.0% vinyltributonoximosilane, 4.45% fumed silica, 0.05% hexamethyldisilazane, 0.05% dibutyltin dilaurate and 0.05% N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane.
Of these, hydroxyl terminated polydimethylsiloxanes are the most common polysiloxane structures. The main chain mainly comprises Si-O bonds and is linked with-CH in a chain measuring way3. The structure has excellent high and low temperature resistance, and can be used for a long time at-60 to +250 ℃. Excellent dielectric property, hydrophobic, moisture-proof, ageing-resistant and electric insulating property.
The nano calcium carbonate is a novel superfine solid powder material, and the granularity of the nano calcium carbonate is between 0.01 and 0.1 mu m. Because of the superfine nano calcium carbonate particles, the crystal structure and the surface electronic structure of the nano calcium carbonate particles are changed, and the quantum size effect, the small size effect, the surface effect and the macroscopic quantum effect which are not possessed by the common calcium carbonate are generated. The nano calcium carbonate is applied to the sealant material, has good affinity with a rubber material, can accelerate the crosslinking reaction of the rubber, greatly improves the thixotropy of a system, enhances the dimensional stability, improves the mechanical property of the rubber, and achieves the dual functions of filling and reinforcing. Meanwhile, the surface of the sizing material can be bright and fine.
Methyl tributyrinoxime silane and vinyl tributyrinoxime silane belong to ketoxime group coupling agents. When used as a crosslinking agent, they may be used in different mildness degrees in the reaction. The cross-linking reaction of the cross-linking agent is ensured to occur in time and the cross-linking agent is ensured to be effective and durable in use by matching.
Dibutyltin dilaurate has excellent light stability and transparency, and can be used as stabilizer for polyvinyl chloride, mainly for soft and semi-soft polyvinyl chloride products, such as transparent film, pipe, artificial leather, etc., and can be used as polyurethane catalyst.
The preparation method of the instant sealing silicone adhesive comprises the following steps of based on the total weight percentage of the instant sealing silicone adhesive to be prepared:
(1) adding 28-32% of hydroxyl-terminated polydimethylsiloxane (20000 cp) and 20-24% of hydroxyl-terminated polydimethylsiloxane (3000cp) into a reaction kettle, heating to 110 ℃, and stirring in vacuum for 3 hours;
(2) cooling to below 50 ℃, putting 35-40% of nano calcium carbonate into the reaction kettle, and stirring for 40min in vacuum;
(3) continuously cooling to below 35 ℃, adding 4.0-6.0% of methyl tributyrinoxime silane, 1.0-2.0% of vinyl tributyrinoxime silane and 3.0-5.0% of meteorological silica into the reaction kettle, and stirring for 10min in vacuum;
(4) and finally, adding 0.03-0.06% of hexamethyldisilazane, 0.03-0.06% of dibutyltin dilaurate and 0.03-0.06% of N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane into the reaction kettle, and fully stirring for 30min under a vacuum condition to obtain the instant sealing silicone adhesive.
The invention has the advantages and beneficial effects that:
1. the hydroxyl-terminated polydimethylsiloxane with 20000cp viscosity and 3000cp viscosity is mixed in the silicone adhesive system, so that the viscosity of the instant sealing silicone adhesive can be effectively controlled, the later construction performance is ensured, and the high strength of the cured silicone adhesive is ensured.
2. According to the invention, the tributylketoxime silane with vinyl and methyl groups is used in a matching manner, so that the silicone adhesive can have initial strength in a short time, and effective curing after sizing can be ensured in long-time storage.
3. The filler of the invention uses nano calcium carbonate, and the excellent affinity of the nano calcium carbonate and the rubber material can not only accelerate the crosslinking reaction of the rubber and greatly improve the thixotropy of the system, but also increase the bonding strength with the interface so as to achieve the dual functions of filling and reinforcing.
4. According to the invention, N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane is selected as a coupling agent, so that the bonding force of the silicone adhesive is improved, and no toxic raw material is introduced while the bonding force is improved, and the storage life of the adhesive is not influenced;
5. the instant sealing silicone adhesive prepared by the invention is a single-component, white, room-temperature moisture curing silicone adhesive, has high curing speed and high initial strength, and can meet the instant sealing requirement. The environment-friendly sealing agent has the characteristics of environmental protection, saving in working procedures, no solvent, good extrudability, high thixotropy, engine oil resistance, excellent chemical medium resistance and the like, and is widely applied to instant sealing of mechanical parts of rail vehicles, automobiles and the like, bonding and sealing of vehicle lamps and lanterns and the like.
Detailed Description
The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
Example 1
An instant sealing silicone adhesive is composed of the following components in percentage by weight: 29.5% hydroxy-terminated polydimethylsiloxane (20000 cp viscosity), 21% hydroxy-terminated polydimethylsiloxane (3000cp viscosity), 38.5% nano calcium carbonate, 5.4% methyltributanonoximosilane, 1.0% vinyltributonoximosilane, 4.45% fumed silica, 0.05% hexamethyldisilazane, 0.05% dibutyltin dilaurate and 0.05% N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane.
The preparation method comprises the following steps of based on the total weight percentage of the instant sealing silicone adhesive to be prepared:
(1) adding 29.5 percent of hydroxyl-terminated polydimethylsiloxane (20000 cp) and 21 percent of hydroxyl-terminated polydimethylsiloxane (3000cp) into a reaction kettle, heating to 110 ℃, and stirring in vacuum for 3 hours;
(2) cooling to below 50 ℃, putting 38.5% of nano calcium carbonate into the reaction kettle, and stirring for 40min in vacuum;
(3) continuously cooling to below 35 ℃, adding 5.4% of methyl tributyrinoxime silane, 1.0% of vinyl tributyrinoxime silane and 4.45% of meteorological silica into the reaction kettle, and stirring for 10min in vacuum;
(4) and finally, adding 0.05 percent of hexamethyldisilazane, 0.05 percent of dibutyltin dilaurate and 0.05 percent of N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane into the reaction kettle, and fully stirring for 30min under the vacuum condition to obtain the instant sealing silicone adhesive.
The performance index of the instant sealing silicone adhesive prepared in this example is shown in Table 1.
As can be seen from Table 1, the sealing pressure of the instant sealing silicone adhesive product produced according to the formula of the invention can reach more than 0.3MPa after 30min of gluing under the condition that other performances are better. Can meet the use requirements of mechanical assembly line work and is beneficial to simplifying the process of the gluing process.
Example 2
An instant sealing silicone adhesive is composed of the following components in percentage by weight: 31.5% hydroxy-terminated polydimethylsiloxane (20000 cp viscosity), 21% hydroxy-terminated polydimethylsiloxane (3000cp viscosity), 36.5% nano calcium carbonate, 4.6% methyltributanonoximosilane, 2.0% vinyltributonoximosilane, 4.25% fumed silica, 0.05% hexamethyldisilazane, 0.04% dibutyltin dilaurate, and 0.06% N- (β -aminoethyl) - γ -aminopropyltrimethoxysilane.
The preparation method comprises the following steps of based on the total weight percentage of the instant sealing silicone adhesive to be prepared:
(1) adding 31.5 percent of hydroxyl-terminated polydimethylsiloxane (20000 cp) and 21 percent of hydroxyl-terminated polydimethylsiloxane (3000cp) into a reaction kettle, heating to 110 ℃, and stirring in vacuum for 3 hours;
(2) cooling to below 50 ℃, putting 36.5% of nano calcium carbonate into the reaction kettle, and stirring for 40min in vacuum; ,
(3) continuously cooling to below 35 ℃, and adding 4.6% of methyl tributyrinoxime silane and 2.0% of vinyl tributyrinoxime silane into the reaction kettle; 4.25 percent of meteorological silica, and stirring for 10min in vacuum;
(4) and finally, adding 0.05 percent of hexamethyldisilazane, 0.04 percent of dibutyltin dilaurate and 0.06 percent of N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane into the reaction kettle, and fully stirring for 30min under the vacuum condition to obtain the instant sealing silicone adhesive.
Example 3
An instant sealing silicone adhesive is composed of the following components in percentage by weight: 28% hydroxy-terminated polydimethylsiloxane (20000 cp viscosity), 23.5% hydroxy-terminated polydimethylsiloxane (3000cp viscosity), 39.2% nano calcium carbonate, 4.5% methyltributanonoximosilane, 1.0% vinyltributonoximosilane, 3.65% fumed silica, 0.05% hexamethyldisilazane, 0.04% dibutyltin dilaurate, and 0.05% N- (β -aminoethyl) - γ -aminopropyltrimethoxysilane.
The preparation method comprises the following steps of based on the total weight percentage of the instant sealing silicone adhesive to be prepared:
(1) adding 32 percent of hydroxyl-terminated polydimethylsiloxane (20000 cp) and 23.5 percent of hydroxyl-terminated polydimethylsiloxane (3000cp) into a reaction kettle, heating to 110 ℃, and stirring in vacuum for 3 hours;
(2) cooling to below 50 ℃, putting 39.2% of nano calcium carbonate into the reaction kettle, and stirring for 40min in vacuum; ,
(3) continuously cooling to below 35 ℃, adding 4.5% of methyl tributyrinoxime silane, 1.0% of vinyl tributyrinoxime silane and 3.65% of gas phase silica into the reaction kettle, and stirring for 10min in vacuum;
(4) and finally, adding 0.05 percent of hexamethyldisilazane, 0.05 percent of dibutyltin dilaurate and 0.05 percent of N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane into the reaction kettle, and fully stirring for 30min under the vacuum condition to obtain the instant sealing silicone adhesive.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included therein.