A kind of production α, the method for alpha, omega-dihydroxy polydimethyl siloxane
Technical field
The present invention relates to a kind of method of producing rubber, specifically, relate to a kind of production α, the method for alpha, omega-dihydroxy polydimethyl siloxane.
Background technology
α, alpha, omega-dihydroxy polydimethyl siloxane are mainly used in and produce condensed type silicon rubber, and its molecular weight size, molecular weight distribution will directly have influence on the performance of the condensed type silicon rubber of being produced.Using octamethylcyclotetrasiloxane (D
4) or dimethyl cyclosiloxane (DMC) production α, in the process of alpha, omega-dihydroxy polydimethyl siloxane, degradation technique plays a decisive role to molecular weight size and distribution.
Traditional mode of production α, the degradation technique of alpha, omega-dihydroxy polydimethyl siloxane: D
4Or DMC and copolymerization such as basic catalyst such as KOH; After the polymerization degree for the treatment of polymkeric substance reached to a certain degree, the stopped reaction still stirred, promptly disposable in reactor the manual liquid water that adds capacity, start then and stir; Behind the 30min, reaction kettle for vacuumizing heats up and removes low-boiling-point substance promptly.
This degradation technique adopts the liquid water of disposable adding capacity, because water just can not full and uniformly be distributed in the polymeric superpolymer, the polymer degradation degree varies causes, and causes resulting α, alpha, omega-dihydroxy polydimethyl siloxane molecular weight distribution broad; And after removing low-boiling-point substance under 170 ℃ of vacuum tightness 0.098Mpa, yield only is 80%~83%.
At the drawback of above technology, domestic have degradation water be heated into steam just directly feed then in polymeric superpolymer inside its technology of degrading, but this method needs vapour pipe is stretched into high viscosity superpolymer inside, vapour pipe easily stops up; And steam feeding amount is difficult for metering, causes the α that produces, alpha, omega-dihydroxy polydimethyl siloxane molecular weight size and distribute wayward, unstable product quality.
Summary of the invention
The purpose of this invention is to provide a kind of molecular weight of product size and the production α more even, high yield that distributes, the method for alpha, omega-dihydroxy polydimethyl siloxane.
In order to realize purpose of the present invention, a kind of production α of the present invention, the method for alpha, omega-dihydroxy polydimethyl siloxane is:
D
4Or DMC and basic catalyst generation copolyreaction, treat that the polymerization degree reaches to a certain degree after, the surface that atomized water is sprayed on polymer product makes it degraded, takes off low-boiling-point substance 2~3h promptly.
Concrete method is: octamethylcyclotetrasiloxane or dimethyl cyclosiloxane and basic catalyst generation copolyreaction, after treating that the polymerization degree reaches 500000~550000Mpas, atomized water all is sprayed on the surface of high viscosity superpolymer product in 8~15s, make it to take place DeR, take off low-boiling-point substance 2~3h.
Described atomized water is 0.1~0.2% of described octamethylcyclotetrasiloxane or a dimethyl cyclosiloxane weight.
Described atomized water is with liquid water gained after the spraying gun atomizing.
Described copolyreaction is at 110~150 ℃, negative pressure 0.03~0.05Mpa, 10~30min.
Described DeR is reacted 3~5min under stirring, preferably 3min.
Carry out under the condition that the described vacuum tightness that removes low-boiling-point substance is 0.090~0.096Mpa.
Described basic catalyst is this area catalyzer commonly used, as KOH, Tetramethylammonium hydroxide.
Production α of the present invention, the whole process of alpha, omega-dihydroxy polydimethyl siloxane all needs to stir, and mixing speed is not had special requirement, can be located at 80r/min.
Described reactor preferably inwall upper end is provided with the vertical response still of liquid water spraying gun.
Adopt a kind of production α of the present invention, the method of alpha, omega-dihydroxy polydimethyl siloxane, since atomized water can be more effective and wide as far as possible be distributed in the high viscosity Polymer Surface, and impel its degraded, solved the problem of liquid water, and made the α that molecular weight is too big or too little the polymer degradation inequality, alpha, omega-dihydroxy polydimethyl siloxane reduces, thereby obviously reduce low-boiling-point substance, improve yield, make ultimate yield reach 87%~90%.
Production α of the present invention, the method of alpha, omega-dihydroxy polydimethyl siloxane is sprayed on atomization water after the polymerisate surface makes it DeR, only need to continue to stir 3~5min, just can reach the purpose that makes the even degraded of high viscosity high polymers, shortened the reaction times.
Adopt the vertical response still,, stop up the situation generation that spraying gun portals thereby stopped polymerization process medium-high viscosity superpolymer product because spraying gun is installed on the inwall upper end of vertical response still.Thereby save production cost, enhance productivity.
Embodiment
Can further be expressly understood the present invention by specific embodiments of the invention given below, but following embodiment not a limitation of the invention.
Embodiment 1
The production method of room temperature vulcanized silicone rubber-107 (RTV-107)
With 300kg D
4Add to 500L vertical response still, open and stir, 170 ℃ of dehydration 1h, add the 0.09kg Tetramethylammonium hydroxide 110 ℃, vacuumize catalyzed polymerization 20min under-0.03Mpa, when treating that superpolymer viscosity reaches 530000Mpas, the vacuum valve of off-response still, the 300g liquid water is sprayed on Polymer Surface makes it degraded after the spraying gun atomizing in 8s, after continuing to stir 5min, be warming up to 170 ℃ rapidly and vacuumize 0.090Mpa, keep 2h, stop to stir, promptly get 267kg RTV-107 (α, alpha, omega-dihydroxy polydimethyl siloxane).
The product RTV-107 theoretical yield of present embodiment is 90%, actual recovery 89%.
Embodiment 2
The production method of room temperature vulcanized silicone rubber-107 (RTV-107)
With 300kg D
4Add to 500L vertical response still, open and stir, 170 ℃ of dehydration 1h, add the 0.11kg Tetramethylammonium hydroxide at 110 ℃, vacuumize catalyzed polymerization 15min under-0.04Mpa, when treating that superpolymer viscosity reaches 500000Mpas, the vacuum valve of off-response still, the 300g liquid water is sprayed on Polymer Surface makes it degraded after the spraying gun atomizing in 10s, after continuing to stir 3min, be warming up to 170 ℃ rapidly and vacuumize 0.093Mpa, keep 2h, stop to stir and promptly get 265kg RTV-107 (α, alpha, omega-dihydroxy polydimethyl siloxane), its theoretical yield is 90%, and actual recovery is 88%.
Embodiment 3
Except that degraded continues to stir the 30min, other condition gets the about 268kg of RTV-107 with embodiment 2, and yield 89% is very nearly the same with 88% yield that stirs 3min.
Take all factors into consideration factors such as yield, energy consumption, continue to stir 3min and have higher economic benefit.
Embodiment 4
The production method of room temperature vulcanized silicone rubber-133 (RTV-133).
With 300kg D
4Add to 500L vertical response still, open and stir, 170 ℃ of dehydration 1h, add 0.04kg KOH at 150 ℃, vacuumize catalyzed polymerization 20min under-0.05Mpa, when treating that superpolymer viscosity reaches 550000Mpas, the vacuum valve of off-response still is sprayed on Polymer Surface with the 350g liquid water and makes it degraded in 15s after the spraying gun atomizing, after continuing to stir 3min, add in an amount of white carbon black and KOH, be warming up to 170 ℃ rapidly and vacuumize 0.096Mpa, keep 2h, stop to stir, promptly get 272kg RTV-133 (α, alpha, omega-dihydroxy polydimethyl siloxane), its theoretical yield is 92%, and reality is yield 90%.
Embodiment 5
The production method of room temperature vulcanized silicone rubber-133 (RTV-133).
300kg DMC is added to 500L vertical response still, open and stir, stirring velocity is 80r/min, 170 ℃ of dehydration 1h, add 0.04kg KOH at 130 ℃, vacuumize catalyzed polymerization 25min under-0.05Mpa, when treating that superpolymer viscosity reaches 540000Mpas, the vacuum valve of off-response still, the 600g liquid water is sprayed on Polymer Surface makes it degraded after the spraying gun atomizing in 15s, after continuing to stir 4min, add in an amount of white carbon black and KOH, be warming up to 170 ℃ rapidly and vacuumize 0.096Mpa, keep 2h, stop to stir, promptly get 272kgRTV-133 (α, alpha, omega-dihydroxy polydimethyl siloxane), its theoretical yield is 91%, and actual recovery is 90%.
What embodiments of the invention adopted is the vertical response still that the inwall upper end is provided with the liquid water spraying gun.
Comparative Examples 1
Traditional technology is produced room temperature vulcanized silicone rubber-133 (RTV-133).
300kg D4 is added to 500L vertical response still, open and stir, 170 ℃ of dehydration 1h add KOH at 150 ℃ of following catalyzed polymerization 30min.When treating that superpolymer viscosity reaches 550000Mpas, the vacuum valve of off-response still.Open the reactor hand hole, the 850g liquid water is added in the reactor, close hand hole, after continuing to stir 30min, add in an amount of white carbon black and KOH, be warming up to 170 ℃ rapidly and vacuumize 0.095Mpa, keep 2h, stop to stir, promptly get 242kg RTV-133 (α, alpha, omega-dihydroxy polydimethyl siloxane), its yield is 80%.
Relatively can find with embodiment 4, adopt production method of the present invention can significantly improve product yield.
Comparative Examples 2
Other condition is with Comparative Examples 1, and the time that will add the continuation stirring of water degraded back is reduced to 5min, gets RTV-133 (α, alpha, omega-dihydroxy polydimethyl siloxane) 228kg, yield 76%.As seen in conventional production methods, take all factors into consideration the weight of yield, energy consumption etc., degraded back churning time 30min should not shorten.
Therefore, compare with traditional production method, when method of the present invention can shorten degradation reaction Between, and significantly improve the yield of product.