CN101125900A - Method for preparing suspension modified polytetrafluoroethylene - Google Patents
Method for preparing suspension modified polytetrafluoroethylene Download PDFInfo
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- CN101125900A CN101125900A CNA2007100468492A CN200710046849A CN101125900A CN 101125900 A CN101125900 A CN 101125900A CN A2007100468492 A CNA2007100468492 A CN A2007100468492A CN 200710046849 A CN200710046849 A CN 200710046849A CN 101125900 A CN101125900 A CN 101125900A
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- vinyl ether
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- persulphate
- tetrafluoroethylene
- propyl vinyl
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Abstract
The invention discloses a method for preparing floating modified polytetrafluror-ethylene (PTFE) by adding a secondary comonomer which is perfluro propyl vinyl ether. Activator used in the method can be persulfate of alkali metals or alkaline-earth metals and a redox initiation system. The reaction temperature changes within a range of 5 DEG C -90 DEG C and the pressure is between 0.5-2.0MPa based on different activating system. The perfluro propyl vinyl ether is added by a vacuum absorption way, so as to avoid using perfluro octoate.
Description
Technical field
The present invention relates to a kind of preparation method of suspension modified polytetrafluoroethylene.
Technical background
After between Roy doctor Plunkett of du pont company in 1938 is accidental, obtaining tetrafluoroethylene, tetrafluoroethylene is with its impayable chemical mediator-resitant property, excellent electrical insulation capability, low-k, extremely low frictional coefficient and can be in-180～260 ℃ of temperature ranges characteristics such as life-time service become a jewel of polymeric material field.
Polytetrafluoroethylene (PTFE) mainly contains two kinds of preparation methods, is respectively emulsion polymerization and suspension polymerization.The product of two kinds of method preparations has different performances, working method and Application Areas.
The particle that letex polymerization obtains is easy to fine, mainly adopts pasty state to push technology.Goods comprise the thin various pipes of the little and wall of diameter, raw material band, fiber, film etc.
The suspension polymerization product is difficult for becoming fine, and main process has plunger to extrude and compression molding.The goods that obtain mainly are to be used for fields such as sealing, insulation, anticorrosion, anti-attrition, and goods comprise pad, turning film, sheet material, bar, pipe etc.The polytetrafluoroethylproducts products that is used for field of sealing technology, for example hydraulic seal parts, O type circle, piston ring etc., usually under the state of bearing certain pressure, work, creep deformation takes place or is called the cold flow phenomenon and deformation quantity big (measuring generally about 9% according to ASTM D621) in the suspension injecting tetrafluoroethylene product of homopolymerization easily under stressing conditions, the definition of creep deformation here is expendable deformation behind the goods stress deformation.For sealing article, this creep deformation is very big to the influence of sealing property.The sealing property of the big more goods of deformation quantity is poor more.Though, by adding other filler, such as metal-powder, glass fibre, carbon fiber, asbestos etc., can improve the creep-resistant property of the polytetrafluoroethylproducts products tetrafluoroethylene of filling (below be called), but sealed in some cases medium may have corrosive nature or tetrafluoroethylene is had purity requirement the filler in the tetrafluoroethylene of filling, and this has just limited the use of the tetrafluoroethylene of filling.Therefore, need under the prerequisite that does not limit the tetrafluoroethylene use, improve the creep property of tetrafluoroethylene.Adding second comonomer is exactly very effective means.
The people that assigned in 1972 introduces the cold flow phenomenon that comonomer improves suspension injecting tetrafluoroethylene for the U.S. Pat 3,655,611 of U.S. Allied Chemical company discloses.According to this patent report, the comonomer that is used for modification of employing is a R 1216, and this patent documentation is limited in R 1216 content in 0.05～0.5mol% scope.From the example of this patent documentation as seen, when R 1216 content is between 0.05～0.5mol%, along with the increase of R 1216 content, the anti-cold flow properties of sample is also progressively improving, but the thermostability of material but becomes worse and worse with the increase of R 1216 content.Therefore, the R 1216 monomer is not that very ideal is used for improving the modification by copolymerization monomer of tetrafluoroethylene creep property.
The U.S. Pat 3,855,191 of artificial du pont company of assigning has been reported the method for perfluoro propyl vinyl ether (PPVE) the modified suspending tetrafluoroethylene that adopts 0.03～0.16% mass percent.Modified Teflon sample that the United States Patent (USP) of Du Pont (US 3,855,191) obtains and existing products (being US 3,655,611 sample) are compared, and have creep-resistant property and thermal stability preferably, but performance are inhomogeneous after sample was made the turning film.
For the US 3 that improves Du Pont, 855, the preparation method's who mentions in 191 defective, the people that assigns is the U.S. Pat 6 of AusimontS.p.A, 262,209 adopt in 15～90% of reaction beginning elder generation adding comonomer total mass, and remainder at the uniform velocity adds in reaction process, to guarantee the uniform distribution of comonomer in polymkeric substance, the polymkeric substance that obtains is formed evenly.
But the preparation method of above-mentioned two patent disclosures mentions and uses perfluorinated surfactant as its essential features.For example, US 6,262, and 209 mention a small amount of negatively charged ion perfluorinated surfactants that use 20-150ppm can make the product of acquisition have good characteristic (especially in turning film field) and improved productivity should to be arranged.
The most representative perfluorinated surfactant is exactly a perfluorooctanoic acid salt, for example ammonium perfluorocaprylate, Sodium perfluorooctanoate etc.The influence of Perfluorocaprylic Acid salt pair environment and the harm of HUMAN HEALTH is more and more caused the extensive concern of society.How to reduce the consumption of perfluorooctanoic acid salt or develop the research focus that its substitute has become fluoropolymer manufacturer.In addition,, but make aftertreatment technology complicated, the waste that has also brought raw material simultaneously though the amount of the perfluorooctanoic acid salt that adds in suspension polymerization system seldom.This be because, in the water medium after the polymerization except natant polytetrafluoroethylsuspending suspending particle, because the existence of perfluorooctanoic acid salt also can form the light emulsion of the very low tetrafluoroethylene of proportion.This light emulsion is got up pretty troublesome as liquid waste disposal, the small amount of polytetrafluoroethylmay that contains in the emulsion be condensed out and what obtain is waste material, and waste water needs conscientiously to handle because of containing perfluorooctanoic acid salt.
Therefore, need exploitation not use the suspension preparation method of the preparation modified Teflon of perfluorinated surfactant, the modified Teflon that makes with this method still has good should have characteristic (especially in turning film field) and improved productivity.
The content of invention
The purpose of this invention is to provide a kind of suspension preparation method of modified Teflon, it does not use perfluorinated surfactant, and the modified Teflon that makes with this method still has good should have characteristic (especially in turning film field) and improved productivity.
Therefore, the invention provides a kind of suspension preparation method of modified Teflon, it comprises the steps:
(1) in the reaction vessel that water is housed that vacuumizes, adds all or part of perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer, make it generating gasification in reaction vessel; The alkyl of described perfluoroalkyl vinyl ether has 1-5 carbon atom;
(2) add radical initiator;
(3) add tetrafluoroethylene monomer;
(4) initiated polymerization; When only adding part perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer in the step (1), then in polymerization process, add remaining perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer continuously.
Embodiment
The invention provides a kind of suspension preparation method of modified Teflon, it comprises the step that adds all or part of perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer in the reaction vessel that water is housed that vacuumizes.
The present invention makes the reaction medium of water as suspension polymerization.The inventive method is injected reaction vessel with water earlier.The add-on of water is without particular limitation, and it can be the consumption of this area routine, and for example, it can account for 1/3 to 2/3 of reaction vessel volume.In an example of the present invention, the volume of the water of adding accounts for 3/5 of reaction vessel volume.
For anti-block disturbs polyreaction, before reaction, need to be equipped with the reaction vessel of water with inert gas purge.Described step with the inert gas purge reaction vessel is this area routine.For example can be lower than 30ppm until wherein oxygen level with the nitrogen purging reaction vessel.
The inventive method is based on such principle, and promptly comonomer is understood generating gasification in reaction vessel under vacuum.The gasiform comonomer can continue to enter aqueous phase and tetrafluoroethylene monomer copolymerization, obtains forming uniform modified Teflon.Need not to use the Perfluorocaprylic Acid salt surfactant with this charging process, thereby advantageously improved the pressure of environment and reduced production cost.
Therefore, need be to vacuumizing through above-mentioned inert gas purge and the qualified reaction vessel of oxygen level.In the present invention, term " oxygen level is qualified " is meant that the volume content of the gas phase oxygen partly of the reaction vessel that water is housed is lower than 100ppm after inert gas purge, better be lower than 50ppm, better is lower than 30ppm.
The inert purge gases that is applicable to the inventive method is without particular limitation, and for example it can be nitrogen, argon gas, neon etc.
The vacuum tightness of reaction vessel is without particular limitation, as long as comonomer that can use keeps gaseous phase.In an example of the present invention, described vacuum tightness be 0.010MPa to 0.090MPa, be preferably 0.030MPa to 0.090MPa, more preferably 0.050MPa is to 0.090MPa.
In order to accelerate and/or guarantee the gasification of comonomer, also can the pressure reacting container that vacuumize be heated.The temperature of heating is without particular limitation, as long as can accelerate and/or guarantee the gasification of comonomer.In an example of the present invention, use perfluoro propyl vinyl ether as comonomer, inert gas purge to oxygen level qualified back vacuumizing the back or vacuumize before pressure reacting container is heated to 10-75 ℃ temperature, better be heated to 20-30 ℃ temperature.
The comonomer that is applicable to the preparation modified Teflon is without particular limitation, and it can be the common modified copolymer monomer in this area.In an example of the present invention, the indefiniteness example of described comonomer has for example perfluor C
1-5Alkyl vinyl ether is as perfluoro methyl vinyl ether, perfluoroethylvinyl ether, perfluoro propyl vinyl ether, perfluorobutyl ethylene base ether and perfluor amyl group vinyl ether; Replace or unsubstituted perfluor dioxole, as the perfluor dioxole, perfluor methoxyl group dioxole (MDO) and two or more mixture in them.
Total add-on of comonomer depends on the purposes of the finished product.Those of ordinary skill in the art can easily determine the total amount of the comonomer that needs add according to the content of comonomer in the finished product.For example, in an example of the present invention, require to contain in the modified Teflon quality percentage composition and be 0.01～0.3% perfluoro propyl vinyl ether.Those of ordinary skill in the art can easily determine the total amount of the perfluoro propyl vinyl ether that needs add in reaction vessel according to this content.
Polymerization process of the present invention does not use fluorochemical surfactant, but adopts the method that comonomer (as perfluoro propyl vinyl ether) is at first gasified in pressure reacting container, makes tetrafluoroethylene and minor amounts of comonomers copolymerization in water medium.
As the example of comonomer principle of the present invention is described with perfluoro propyl vinyl ether below: because tetrafluoroethylene is a kind of active monomer, be easy to homopolymerization, but the ratio of the reactivity ratio of perfluoro propyl vinyl ether monomer during with the tetrafluoroethylene copolymerization is approximately 0.06: 8.7, illustrates that the two active difference is bigger.This expression perfluoro propyl vinyl ether is difficult to receive on the tetrafluoroethylene main chain, we can say also that perhaps the polymerization of perfluoro propyl vinyl ether Paratetrafluoroethylene has inhibition.Therefore, can cause induction period in polymerization to prolong if add the required whole perfluoro propyl vinyl ethers of reaction in reaction forward direction system, the starting stage speed of reaction is formed than low and product may skewness.So prior art (as US 6,262,209) adopts at the reaction initial period and adds the perfluoro propyl vinyl ether monomer that accounts for total amount 30～75%, all the other perfluoro propyl vinyl ether monomers add continuously in reaction beginning back.But the shortcoming of this method is to need to use fluorochemical surfactant.It has improved production cost and has increased environmental stress simultaneously.
The present invention controls the copolymerization of perfluoro propyl vinyl ether and tetrafluoroethylene monomer according to perfluoro propyl vinyl ether boiling point characteristics low and that vaporize easily at normal temperatures.Specific practice is, the high-pressure reaction vessel that adds reaction medium water is repeatedly found time, and oxygen level is reached below the 30ppm, will react required perfluoro propyl vinyl ether sucting reaction container then under vacuum state.Because the perfluoro propyl vinyl ether that sucks can be gasified totally in reaction vessel, thereby form gas phase mixture with the tetrafluoroethylene monomer that adds, perfluoro propyl vinyl ether can enter reaction medium with tetrafluoroethylene in reaction process, and the perfluoro propyl vinyl ether monomer concentration in the gas phase mixture is reduced gradually with constantly replenishing of tetrafluoroethylene monomer, avoided having too much perfluoro propyl vinyl ether in the reaction medium and the problem that influences speed of response and product quality.
In order further to control the content of comonomer (as perfluoro propyl vinyl ether) in the reaction system, can be as prior art (as US 6,262,209) the described perfluoro propyl vinyl ether monomer that accounts for total amount 30～75% in the adding of reaction initial period, but described perfluoro propyl vinyl ether monomer is to add in the pressure reacting container with vacuum tightness, and remaining perfluoro propyl vinyl ether monomer can add along with the carrying out of reaction as prior art gradually.
Initiator of polyreaction system of the present invention is without particular limitation, it can adopt the persulphate of basic metal or alkaline-earth metal, such as Potassium Persulphate, Sodium Persulfate and ammonium persulphate etc., also can use redox initiation system, oxygenant is similarly the persulphate of basic metal or alkaline-earth metal, and such as Potassium Persulphate, ammonium persulphate, reductive agent is a sulphite, as S-WAT, sodium bisulfite, Sodium Metabisulfite etc.When using the redox initiation system initiated polymerization, can add cupric, monovalence silver plasma, polyreaction of the present invention is according to the difference of used initiator type, and temperature of reaction is at 5 ℃～90 ℃.
Be subjected to the corrosion situation for what reduce reactor, can add pH value conditioning agent in system, as ammoniacal liquor, yellow soda ash, SODIUM PHOSPHATE, MONOBASIC, Sodium phosphate dibasic, volatile salt, Sodium Tetraborate etc. make reaction system be neutrality or meta-alkalescence.
Bivalent cupric ion and monovalence silver ions relatively are easy to generate precipitation under alkaline condition, for fear of sedimentary generation, can add the complexing stablizer that can form title complex with them, such as EDTA (ethylenediamine tetraacetic acid (EDTA)).
Because the low reactive behavior of perfluoro propyl vinyl ether, the pressure that increases tetrafluoroethylene monomer in the reaction system is equivalent to increase the concentration of tetrafluoroethylene monomer, and this is unfavorable for the copolymerization of perfluoro propyl vinyl ether and tetrafluoroethylene in some cases.In a better example of the present invention, the pressure of tetrafluoroethylene monomer should be too not high, and it is proper being controlled at 0.5～2.0MPa.
Further specify the present invention below in conjunction with embodiment.
Embodiment
Testing method
1. the content of perfluoro propyl vinyl ether in the mensuration multipolymer
The content of perfluoro propyl vinyl ether is determined by infrared spectroscopy in the sample.Concrete grammar is: the testing sample particle is pressed into transparent film, film is put on the Fourier infrared spectrograph analyzes then, calculating wave number from the infrared spectrum that obtains is 2365cm
-1And 994cm
-1Absorption peak strength A, calculate the content of perfluoro propyl vinyl ether according to peak area ratio.
2. measure the standard relative density of multipolymer
The test of the standard relative density (SSG) of sample is carried out according to HG/T 2903-1997 standard.
3. measure the tensile strength and the breaking tenacity of multipolymer
The tensile strength of sample and the test of elongation at break are carried out according to HG/T 2903-1997 standard.
Embodiment 1
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 20 ℃, vacuum sucks the perfluoro propyl vinyl ether of 19 grams, adds the redox initiation system that Potassium Persulphate and S-WAT are formed, tetrafluoroethylene monomer pressure in the still is raised to 0.8MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 2
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 30 ℃, vacuum sucks the perfluoro propyl vinyl ether of 19 grams, adds the redox initiation system that Potassium Persulphate and S-WAT are formed, tetrafluoroethylene monomer pressure in the still is raised to 1.2MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 3
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 10 ℃, vacuum sucks the perfluoro propyl vinyl ether of 19 grams, adds the redox initiation system that Potassium Persulphate and sodium bisulfite are formed, tetrafluoroethylene monomer pressure in the still is raised to 1.5MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 4
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor be warming up to 30 ℃, vacuum sucks the perfluoro propyl vinyl ether of 19 grams, add the redox initiation system that Potassium Persulphate and S-WAT are formed, add the 5ml1% copper-bath, tetrafluoroethylene monomer pressure in the still is raised to 1.0MPa, start stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 5
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 30 ℃, vacuum sucks the perfluoro propyl vinyl ether of 19 grams, adds the redox initiation system that ammonium persulphate and S-WAT are formed, tetrafluoroethylene monomer pressure in the still is raised to 1.2MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 6
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 75 ℃, vacuum sucks the perfluoro propyl vinyl ether of 40 grams, adds Potassium Persulphate, TFE monomer pressure in the still is raised to 1.2MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 7
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 75 ℃, vacuum sucks the perfluoro propyl vinyl ether of 18.7 grams, adds Potassium Persulphate, tetrafluoroethylene monomer pressure in the still is raised to 1.2MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reach 3% transformation efficiency when tetrafluoroethylene after, add perfluoro propyl vinyl ether with the ratio of 0.05 gram/kg tetrafluoroethylene and finish until reaction.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Comparative example 1
With with United States Patent (USP) 6,262, the following sample that makes of method that the embodiment 3 of 109B1 is identical:
At a cumulative volume is to add 550 liters of water through the deionization and the degassing, 5.8 gram Potassium Persulphates, 2.2 gram (NH in 1100 liters the vertical response still
4)
2Fe (SO
4)
26H
2O and 45 gram Sodium perfluorooctanoates.Remove the oxygen of reactor head with nitrogen purging.Add 250 gram perfluoro propyl vinyl ethers.The tetrafluoroethylene that when 580rpm stirs, adds 17 crust.In pressurization, add 480 gram Na
4P
2O
710H
2O.This reactor is incubated in 75 ℃ of also continuous tetrafluoroethylene that add to keep reactor pressure constant.Ratio with the 1g/kg tetrafluoroethylene after reaching 3% tetrafluoroethylene transformation efficiency adds perfluoro propyl vinyl ether, finishes until reaction.
Reaction is reclaimed unreacted TFE monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 8
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 75 ℃, vacuum sucks the perfluor methoxyl group dioxole of 13 grams, adds Potassium Persulphate, tetrafluoroethylene monomer pressure in the still is raised to 1.2MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Embodiment 9
In 50 liters of reactors, inject 30 liters of deionized waters, use high pure nitrogen air at least 3 times in the replacement reaction kettle repeatedly, detect oxygen level in the still then, be lower than 30ppm up to oxygen level, after oxygen level is qualified reactor is warming up to 75 ℃, vacuum sucks the perfluor methoxyl group dioxole of 12.7 grams, adds Potassium Persulphate, tetrafluoroethylene monomer pressure in the still is raised to 1.2MPa, starts stirring and begin reaction.Keep temperature of reaction in ± 5 ℃ scope, to fluctuate in the reaction process.Reach 3% transformation efficiency when tetrafluoroethylene after, add perfluor methoxyl group dioxole with the ratio of 0.05 gram/kg tetrafluoroethylene and finish until reaction.Reaction is reclaimed unreacted tetrafluoroethylene monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Comparative example 2
With with United States Patent (USP) 6,262, the following sample that makes of method that the embodiment 4 of 209B1 is identical:
At a cumulative volume is to add 550 liters of water through the deionization and the degassing, 5.8 gram Potassium Persulphates, 2.2 gram (NH in 1100 liters the vertical response still
4)
2Fe (SO
4)
26H
2O and 45 gram Sodium perfluorooctanoates.Remove the oxygen of reactor head with nitrogen purging.Add 130 gram perfluor methoxyl group dioxoles.The tetrafluoroethylene that when 580rpm stirs, adds 17 crust.In pressurization, add 480 gram Na
4P
2O
710H
2O.This reactor is incubated in 75 ℃ of also continuous tetrafluoroethylene that add to keep reactor pressure constant.Ratio with the 1g/kg tetrafluoroethylene after reaching 3% tetrafluoroethylene transformation efficiency adds perfluor methoxyl group dioxole, finishes until reaction.
Reaction is reclaimed unreacted TFE monomer after finishing, and sheds the still internal pressure, obtains fibrous particle.Polymerisate is used deionization washing 3 times.Then washed polymkeric substance is placed in the baking oven 150 ℃ dry 24 hours down, be ground into particle diameter less than 50 microns particle.The particle that crushes can be used for doing various tests.
Table 1 has been listed the performance index of the sample that the foregoing description and comparative example obtain.
The performance index of sample in table 1 embodiment and the comparative example
| PPVE content (%) | MDO content (%) | Tensile strength (MPa) | Elongation at break (%) | SSG | |
| Embodiment 1 | 0.014 | - | 28.5 | 392 | 2.15 |
| Embodiment 2 | 0.108 | - | 31.3 | 364 | 2.16 |
| Embodiment 3 | 0.059 | - | 38.4 | 308 | 2.14 |
| Embodiment 4 | 0.103 | - | 33.1 | 414 | 2.16 |
| Embodiment 5 | 0.264 | - | 27.8 | 325 | 2.14 |
| Embodiment 6 | 0.123 | - | 33.2 | 371 | 2.15 |
| Embodiment 7 | 0.112 | - | 37.4 | 380 | 2.15 |
| Comparative example 1 | 0.132 | - | 36 | 480 | 2.18 |
| Embodiment 8 | - | 0.125 | 33.2 | 369 | 2.16 |
| Embodiment 9 | - | 0.130 | 31.2 | 402 | 2.15 |
| Comparative example 2 | - | 0.1 | 34 | 350 | 2.16 |
By top test-results as seen, need not to use environmentally harmful fluorochemical surfactant with the inventive method, the modified Teflon that obtains has and the prior art similar performance.
Describe the present invention in conjunction with the embodiments above.Should be appreciated that above-mentioned explanation only is exemplary, under the situation that does not depart from the claims spirit and scope, those of ordinary skill in the art can carry out various improvement and variation to the present invention.
Claims (10)
1. the suspension preparation method of a modified Teflon, it comprises the steps:
(1) in the reaction vessel that water is housed that vacuumizes, adds all or part of perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer, make it generating gasification in reaction vessel; The alkyl of described perfluoroalkyl vinyl ether has 1-5 carbon atom;
(2) add radical initiator;
(3) add tetrafluoroethylene monomer;
(4) initiated polymerization;
When only adding part perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer in the step (1), then in polymerization process, add remaining perfluoroalkyl vinyl ether and/or perfluor dioxole comonomer continuously.
2. the method for claim 1 is characterized in that described perfluoroalkyl vinyl ether is a perfluoro propyl vinyl ether.
3. the method for claim 1 is characterized in that described radical initiator is selected from the persulphate or the redox initiation system of basic metal or alkaline-earth metal.
4. method as claimed in claim 3 is characterized in that the persulphate of described basic metal or alkaline-earth metal is selected from Potassium Persulphate, Sodium Persulfate and ammonium persulphate; Oxygenant is the persulphate of basic metal or alkaline-earth metal in the described redox initiation system, and reductive agent is a sulphite.
5. method as claimed in claim 4 is characterized in that described oxygenant is selected from Potassium Persulphate, ammonium persulphate; Described reductive agent is selected from S-WAT, sodium bisulfite, Sodium Metabisulfite.
6. as each described method among the claim 1-5, it is characterized in that polymeric reaction temperature is 5 ℃～90 ℃, preferred 10 ℃～80 ℃; The reaction pressure of reaction system is 0.5～2.0MPa, preferred 0.5～1.5MPa.
7. as each described method among the claim 1-5, the quality percentage composition that it is characterized in that the perfluoro propyl vinyl ether in the suspension modified polytetrafluoroethylene is 0.01～0.3%, preferred 0.06～0.13%.
8. as each described method among the claim 1-5, it is characterized in that it comprises that also adding is selected from the step of bivalent cupric ion, monovalence silver ions or its mixture.
9. as each described method among the claim 1-5, it is characterized in that it comprises that also adding is selected from ammoniacal liquor, yellow soda ash, SODIUM PHOSPHATE, MONOBASIC, Sodium phosphate dibasic, the step of volatile salt, Sodium Tetraborate makes reaction system be neutrality or meta-alkalescence.
10. method as claimed in claim 8 is characterized in that it comprises that also adding can form the step of the complexing stablizer of title complex with bivalent cupric ion and monovalence silver ions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100468492A CN100554289C (en) | 2007-10-09 | 2007-10-09 | A kind of preparation method of suspension modified polytetrafluoroethylene |
Applications Claiming Priority (1)
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| CN101797786A (en) * | 2010-03-26 | 2010-08-11 | 四会市封王氟塑有限公司 | Novel intelligent invisible anti-theft network line and method for making insulating protective layer thereof |
| CN102086243A (en) * | 2010-12-01 | 2011-06-08 | 中昊晨光化工研究院 | Method for preparing high-gloss PTFE (Polytetrafluoroethylene) dispersion concentrated solution |
| CN101724117B (en) * | 2009-11-27 | 2013-03-06 | 中昊晨光化工研究院 | Preparation method for large molded sheet suspended PTFE resin |
| US8575287B2 (en) | 2008-05-21 | 2013-11-05 | Asahi Glass Company, Limited | Method for producing polytetrafluoroethylene fine powder |
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| CN102086243B (en) * | 2010-12-01 | 2012-08-08 | 中昊晨光化工研究院 | Method for preparing high-gloss PTFE (Polytetrafluoroethylene) dispersion concentrated solution |
| CN103864979A (en) * | 2014-03-06 | 2014-06-18 | 山东华夏神舟新材料有限公司 | Fluorine-containing polymer and preparation method thereof |
| CN105924561A (en) * | 2016-06-16 | 2016-09-07 | 浙江巨圣氟化学有限公司 | Preparation method of modified teflon resin |
| CN114085309A (en) * | 2021-11-22 | 2022-02-25 | 浙江巨化技术中心有限公司 | Solution polymerization preparation method of perfluorosulfonic acid resin |
| CN114213569A (en) * | 2021-11-22 | 2022-03-22 | 浙江巨化技术中心有限公司 | Suspension polymerization preparation method of perfluorosulfonic acid resin |
| CN114276482A (en) * | 2021-11-22 | 2022-04-05 | 浙江巨化技术中心有限公司 | Emulsion polymerization preparation method of perfluorosulfonic acid resin |
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