CN102329402B - Preparation method of low-temperature-resistant binary fluorine rubber - Google Patents
Preparation method of low-temperature-resistant binary fluorine rubber Download PDFInfo
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Abstract
The invention relates to a preparation method of low-temperature-resistant binary fluorine rubber, belonging to the technical field of fluorine chemical industry. The preparation method is characterized by comprising the following steps of: 1) mixing 1,1-difluoroethylene, hexafluoropropylene and perfluoro methyl vinyl ether in a molar ratio of (60-80):(15-30):(2-8) to obtain a monomer mixture forlater use; and 2) reacting the monomer mixture in an aqueous dispersion form under the action of an initiator, an emulsifier and a chain transfer agent in a reaction kettle, adjusting the temperatureto 60-95 DEG C, pressure to 1.0-3.0MPa and stirring rate to 400-700 r/min, and carrying out copolymerization reaction for 3-7 hours to obtain a finished product. The preparation method of the low-temperature-resistant binary fluorine rubber has the advantages that the preparation process is simple, the use amount of expensive perfluoro methyl vinyl ether in the reaction is low, and the productioncost is greatly lowered; and the glass transition temperature of the prepared fluorine rubber can be effectively reduced by 2-7 DEG C and the brittleness temperature is reduced by 10-18 DEG C, thereby being suitable for low-temperature sealing requirements.
Description
Technical field
The invention belongs to the fluorine chemical technical field, be specially the preparation method of low temperature resistant binary viton.
Background technology
Based on 1, the binary viton of 1-difluoroethylene (VDF), R 1216 (HFP) has outstanding high temperature resistant, oil resistant, resistance to chemical attack and performance such as ageing-resistant, but exist the relatively poor weakness of resistance to low temperature simultaneously, usually the second-order transition temperature (Tg) of binary viton is-17 ℃, and temperature limit of brittleness (Th) is-20 ℃.
Yet for a lot of engineerings were used, crucial threshold application was that Tg is no more than-19 ℃, and Th is no more than-30 ℃, and therefore, rubber engineering teacher have made huge effort for the low temperature flexibility that improves viton.Usually, the low-temperature performance of viton depends primarily on the molecular structure of rubber, because of backbone structure, and pendant groups, when polarity etc. change, Tg, Th also changes thereupon.Tg is along with the increase and decrease of the degree of branching is remarkable; The degree of branching hour, the free volume between polymer molecule is less, the reactive force between molecular chain is bigger, polymer molecule chain movement energy needed is also just bigger, so Tg is higher; On the contrary, the free volume between the bigger polymer molecule of the degree of branching is also bigger, and the interaction force between molecular chain is little, and what molecular chain movement needed is can energy also just less, and Tg is lower.From molecular structure, glass transition is a kind of relaxation phenomenon of superpolymer pars amorpha from the frozen state to the thawed state.Be in the glass crystalline state at the following superpolymer of Tg, molecular chain and segment all can not move, and the atom (or group) that just constitutes molecule vibrates in its equilibrium theory of tide; And when Tg is above the molecule segment setting in motion, show high-elastic character.For low temperature resistant viton, weigh its resistance to low temperature with Th and have more practical significance.
The method that the low temperature resistant viton of current production generally uses is to introduce the big new monomer-perfluoro methyl vinyl ether (PMVE) of a kind of steric hindrance on the basis of VDF, TFE monomer to carry out copolymerization.Perfluoro methyl vinyl ether can improve the low temperature flexibility of viton significantly, reduces Tg and Th effectively.Documents about the viton that contains the PMVE monomer can be mentioned patent CN85109162, CN1152583A, EP-A525685.In order to obtain the lower fluoroelastomer of Tg, need to add considerable polymerization single polymerization monomer PMVE, its consumption is usually in 20%～40%(molar fraction) between.This has just directly caused very expensive production cost, and on the other hand, PMVE content is more high, and the reactive behavior of comonomer is more low, and polymerization velocity is more slow, and yield is also just more low, is unfavorable for very much commercially producing in batches.
Summary of the invention
At the above-mentioned problems in the prior art, the objective of the invention is to design the preparation method's that a kind of low temperature resistant binary viton is provided technical scheme, its second-order transition temperature and temperature limit of brittleness obviously reduce, and technology is simple, and production cost is low.
The preparation method of described low temperature resistant binary viton is characterized in that may further comprise the steps:
1) with mol ratio be vinylidene fluoride, R 1216, the perfluoro methyl vinyl ether compositing monomer mixture of 60-80:15-30:2-8, standby;
2) with above-mentioned monomer mixture with the form of aqueous dispersion under the effect of initiator, emulsifying agent and chain-transfer agent in reaction kettle for reaction, adjust the temperature to 60～95 ℃, pressure to 1.0～3.0Mpa, stir speed (S.S.) to 400～700r/min makes the finished product through 3～7 hours copolyreaction.
The preparation method of described low temperature resistant binary viton is characterized in that: polymerization reaction kettle is then used nitrogen purging with the air in the water-filled method removal reactor; Then distilled water, initiator, emulsifying agent are introduced in the reactor; Again monomer mixture is added in the reactor by compressor, made the pressure in the reactor reach 0.3-0.4Mpa, reaction mixture is heated to 60-95 ℃; In the process of reaction, add monomer mixture in batches or continuously pressure is adjusted to 1.0-3.0Mpa; Keep the stir speed (S.S.) of 400-700r/min to keep speed of reaction simultaneously; Behind reaction 1.0-2.0h, add chain-transfer agent by volume pump; Continue behind the reaction 2-5h reaction mixture to be cooled off termination reaction; The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, extruding is made film by mill behind the drying and dehydrating.
The preparation method of described low temperature resistant binary viton is characterized in that: described initiator is persulphate, persulphate-hydrosulphite or di-isopropyl peroxydicarbonate; Described emulsifying agent is the lithium salts of the sodium salt of Perfluorocaprylic Acid or ammonium salt, perfluoro capryl sulfuric acid; Described chain-transfer agent is acetone, diethyl malonate, iso-pentane or vinyl acetic monomer; By 100 listed as parts by weight, all the other auxiliary agents are respectively the add-on of component: initiator 0.03-0.15, emulsifying agent 0.02-0.75, chain-transfer agent 0.07-1.5 with distilled water.
The preparation method of described low temperature resistant binary viton is characterized in that in the step 1): the mol ratio of vinylidene fluoride, R 1216, perfluoro methyl vinyl ether is 65-75:20-25:3.5-6.5, preferred 70-72:22-24:4-6.
The preparation method of described low temperature resistant binary viton is characterized in that step 2) in: temperature of reaction is 65～90 ℃, preferred 70～85 ℃, and more preferably 75～80 ℃.
The preparation method of described low temperature resistant binary viton is characterized in that step 2) in: reaction pressure is 1.5～2.5Mpa, preferred 1.6～2.4Mpa, more preferably 1.8～2.2Mpa.
The preparation method of described low temperature resistant binary viton is characterized in that step 2) in: stir speed (S.S.) is 450～650r/min, preferred 500～600r/min, more preferably 550～580r/min.
The preparation method of described low temperature resistant binary viton is characterized in that step 2) in: the reaction times is 4～6 hours, preferred 4.5～5.5 hours.
The preparation method of described low temperature resistant binary viton is characterized in that: distilled water is by 100 listed as parts by weight, and the weight part of all the other auxiliary agents is respectively: initiator 0.05-0.12, preferred 0.08-0.10; Emulsifying agent 0.04-0.70, preferred 0.05-0.60; Chain-transfer agent 0.1-1.2, preferred 0.5-1.0.
Comonomer is after being mixed by self-measuring device, adds into reactor by compressor, and polymerization is then injected reactor by volume pump with chemical reagent.
Initiator can be selected organic or inorganic superoxide such as persulphate, persulphate-hydrosulphite, di-isopropyl peroxydicarbonate for use.Emulsifying agent can be selected the lithium salts based on the sodium salt of the water-soluble salt of the perfluoro carboxylic acid of HFC-236fa oxide compound oligopolymer such as Perfluorocaprylic Acid or ammonium salt and perfluoro capryl sulfuric acid for use.Polymericular weight can be by regulating initiator amount and selecting for use chain-transfer agent to control simultaneously, and chain-transfer agent commonly used has acetone, diethyl malonate, iso-pentane and vinyl acetic monomer etc.Chain-transfer agent can join before polymerization begins in the solution, also can constantly add in polymerization process in batches.
The temperature of reaction of letex polymerization is between 60～95 ℃, and this depends on the reactivity of used comonomer and the needed performance index of viton of the present invention to be produced.The reaction pressure of letex polymerization is between 1.0～3.0MPa, and this depends on required polymkeric substance speed and each component content.
The stir speed (S.S.) of letex polymerization is between 400～700r/min, because for the emulsion polymerization of gas phase monomer, it is to realize by the process of gas phase monomer to liquid phase dissolved that the monomer in the polymerization process replenishes.If react under lower stir speed (S.S.), the dissolution process of monomer is slower, becomes the control step of speed of reaction, has only when stir speed (S.S.) to reach certain intensity, just can clear up the influence of dissolution process, and polymerization rate is just controlled by chemical reaction.
The preparation method of above-mentioned low temperature resistant binary viton, with 1, the monomer mixture that 1-difluoroethylene, R 1216, perfluoro methyl vinyl ether are formed reacts under the effect of initiator, emulsifying agent and chain-transfer agent and makes, its preparation technology is simple, expensive perfluoro methyl vinyl ether consumption is few in the reaction, has significantly reduced production cost; The viton that makes can effectively reduce by 2～7 ℃ of second-order transition temperatures, and 10～18 ℃ of temperature limit of brittleness are to adapt to the requirement of low temperature seal.
The percentage composition that relates among the present invention except other has explanation, other be weight percentage.
Embodiment
It is following that the invention will be further described by embodiment.
Embodiment 1
At 1m
3Polymerization reaction kettle in, remove air in the reactor with water-filled method, use nitrogen purging then, oxygen level is more low more good.With 450Kg distilled water, 0.65Kg Potassium Persulphate, 0.15Kg ammonium perfluorocaprylate are introduced in the reactor then, and VDF, HFP, PMVE are introduced in the medial launder with the monomer mixture that the mol ratio of 73:24:3 is formed, and the pressure that makes basin during introducing is 5MPa, normal temperature.The outlet of a certain amount of monomer mixture by tank bottom is transported in the reactor, makes the pressure in the reactor reach 0.35MPa.Reaction mixture is heated to 73 ℃.By introducing more above-mentioned monomer mixture pressure is adjusted to 2.0MPa.Reaction beginning back pressure descends, and by periodically introducing above-mentioned monomer mixture to keep pressure-stabilisation, keeps the stir speed (S.S.) of 550r/min to keep speed of reaction simultaneously.Behind reaction 1.0h, add 5.5Kg propanedioic acid diethyl fat by volume pump.Behind the 2h reaction mixture is cooled off termination reaction.The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, moisture are removed in 105 ℃ of down dry 8h in the extruding back, make product of the present invention finally by mill mixing.The second-order transition temperature of this viton is-19 ℃ after measured, and temperature limit of brittleness is-30 ℃.
Embodiment 2
At 1m
3Polymerization reaction kettle in, remove air in the reactor with water-filled method, use nitrogen purging then, oxygen level is more low more good.With 450Kg distilled water, 0.15Kg Potassium Persulphate, 0.10Kg ammonium perfluorocaprylate are introduced in the reactor then, and VDF, HFP, PMVE are introduced in the medial launder with the monomer mixture that the mol ratio of 70:24:6 is formed, and the pressure that makes basin during introducing is 5MPa, normal temperature.The outlet of a certain amount of monomer mixture by tank bottom is transported in the reactor, makes the pressure in the reactor reach 0.40MPa.Reaction mixture is heated to 85 ℃.By introducing more above-mentioned monomer mixture pressure is adjusted to 2.5MPa.Reaction beginning back pressure descends, and by periodically introducing above-mentioned monomer mixture to keep pressure-stabilisation, keeps the stir speed (S.S.) of 685r/min to keep speed of reaction simultaneously.Behind reaction 2.2h, add 1.4Kg propanedioic acid diethyl fat by volume pump.4.7h after reaction mixture is cooled off termination reaction.The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, moisture are removed in 105 ℃ of down dry 8h in the extruding back, make product of the present invention finally by mill mixing.The second-order transition temperature of this viton is-22 ℃ after measured, and temperature limit of brittleness is-36 ℃.
Embodiment 3
At 1m
3Polymerization reaction kettle in, remove air in the reactor with water-filled method, use nitrogen purging then, oxygen level is more low more good.With 450Kg distilled water, 0.35Kg ammonium persulphate, 3.3Kg Perfluorocaprylic Acid are introduced in the reactor then, and VDF, HFP, PMVE are introduced in the medial launder with the monomer mixture that the mol ratio of 64:28:8 is formed, and the pressure that makes basin during introducing is 5MPa, normal temperature.The outlet of a certain amount of monomer mixture by tank bottom is transported in the reactor, makes the pressure in the reactor reach 0.38MPa.Reaction mixture is heated to 78 ℃.By introducing more above-mentioned monomer mixture pressure is adjusted to 1.5MPa.Reaction beginning back pressure descends, and by periodically introducing above-mentioned monomer mixture to keep pressure-stabilisation, keeps the stir speed (S.S.) of 580r/min to keep speed of reaction simultaneously.Behind reaction 1.3h, add 6.6Kg propanedioic acid diethyl fat by volume pump.4.1h after reaction mixture is cooled off termination reaction.The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, moisture are removed in 105 ℃ of down dry 8h in the extruding back, make product of the present invention finally by mill mixing.The second-order transition temperature of this viton is-24 ℃ after measured, and temperature limit of brittleness is-38 ℃.
Embodiment 4
At 1m
3Polymerization reaction kettle in, remove air in the reactor with water-filled method, use nitrogen purging then, oxygen level is more low more good.With 450Kg distilled water, 0.57Kg ammonium persulphate, 2.4Kg Perfluorocaprylic Acid are introduced in the reactor then, and VDF, HFP, PMVE are introduced in the medial launder with the monomer mixture that the mol ratio of 77:17:6 is formed, and the pressure that makes basin during introducing is 5MPa, normal temperature.The outlet of a certain amount of monomer mixture by tank bottom is transported in the reactor, makes the pressure in the reactor reach 0.42MPa.Reaction mixture is heated to 90 ℃.By introducing more above-mentioned monomer mixture pressure is adjusted to 1.5MPa.Reaction beginning back pressure descends, and by periodically introducing above-mentioned monomer mixture to keep pressure-stabilisation, keeps the stir speed (S.S.) of 660r/min to keep speed of reaction simultaneously.Behind reaction 1.3h, add 4.9Kg propanedioic acid diethyl fat by volume pump.4.3h after reaction mixture is cooled off termination reaction.The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, moisture are removed in 105 ℃ of down dry 8h in the extruding back, make product of the present invention finally by mill mixing.The second-order transition temperature of this viton is-21 ℃ after measured, and temperature limit of brittleness is-34 ℃.
Embodiment 5
At 1m
3Polymerization reaction kettle in, remove air in the reactor with water-filled method, use nitrogen purging then, oxygen level is more low more good.With 450Kg distilled water, 0.60Kg ammonium persulphate, 1.1Kg Perfluorocaprylic Acid are introduced in the reactor then, and VDF, HFP, PMVE are introduced in the medial launder with the monomer mixture that the mol ratio of 75:21:4 is formed, and the pressure that makes basin during introducing is 5MPa, normal temperature.The outlet of a certain amount of monomer mixture by tank bottom is transported in the reactor, makes the pressure in the reactor reach 0.35MPa.Reaction mixture is heated to 63 ℃.By introducing more above-mentioned monomer mixture pressure is adjusted to 1.5MPa.Reaction beginning back pressure descends, and by periodically introducing above-mentioned monomer mixture to keep pressure-stabilisation, keeps the stir speed (S.S.) of 500r/min to keep speed of reaction simultaneously.Behind reaction 1.1h, add 0.35Kg propanedioic acid diethyl fat by volume pump.2.8h after reaction mixture is cooled off termination reaction.The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, moisture are removed in 105 ℃ of down dry 8h in the extruding back, make product of the present invention finally by mill mixing.The second-order transition temperature of this viton is-20 ℃ after measured, and temperature limit of brittleness is-33 ℃.
Embodiment 1-5 explanation, expensive PMVE can partly mix in the polymerization process of binary viton and prepare resistance to low temperature than more excellent viton, and, the usage quantity of PMVE is little, not having again increases operation sequence extraly, and the engineering application facet all is acceptable producing still.
Claims (9)
1. the preparation method of low temperature resistant binary viton is characterized in that may further comprise the steps:
1) with mol ratio be vinylidene fluoride, R 1216, the perfluoro methyl vinyl ether compositing monomer mixture of 60-80:15-30:2-8, standby;
2) polymerization reaction kettle is then used nitrogen purging with the air in the water-filled method removal reactor; Then distilled water, initiator, emulsifying agent are introduced in the reactor; Again monomer mixture is added in the reactor by compressor, made the pressure in the reactor reach 0.3-0.4MPa, reaction mixture is heated to 60-95 ℃; In the process of reaction, add monomer mixture in batches or continuously pressure is adjusted to 1.0-3.0MPa; Keep the stir speed (S.S.) of 400-700r/min to keep speed of reaction simultaneously; Behind reaction 1.0-2.0h, add chain-transfer agent by volume pump; Continue behind the reaction 2-5h reaction mixture to be cooled off termination reaction; The latex of polymerization gained condensed obtain the fragmental polymkeric substance, through washing, filter, extruding is made film by mill behind the drying and dehydrating;
Described initiator is persulphate, persulphate-hydrosulphite or di-isopropyl peroxydicarbonate; Described emulsifying agent is the lithium salts of the sodium salt of Perfluorocaprylic Acid or ammonium salt, perfluoro capryl sulfuric acid; Described chain-transfer agent is acetone, diethyl malonate, iso-pentane or vinyl acetic monomer; By 100 listed as parts by weight, all the other auxiliary agents are respectively the add-on of component: initiator 0.03-0.15, emulsifying agent 0.02-0.75, chain-transfer agent 0.07-1.5 with distilled water.
2. the preparation method of low temperature resistant binary viton as claimed in claim 1, it is characterized in that in the step 1): the mol ratio of vinylidene fluoride, R 1216, perfluoro methyl vinyl ether is 65-75:20-25:3.5-6.5.
3. the preparation method of low temperature resistant binary viton as claimed in claim 1, it is characterized in that in the step 1): the mol ratio of vinylidene fluoride, R 1216, perfluoro methyl vinyl ether is 70-72:22-24:4-6.
4. the preparation method of low temperature resistant binary viton as claimed in claim 1 is characterized in that step 2) in: temperature of reaction is 65～90 ℃.
5. the preparation method of low temperature resistant binary viton as claimed in claim 1 is characterized in that step 2) in: temperature of reaction is 70～85 ℃.
6. the preparation method of low temperature resistant binary viton as claimed in claim 1 is characterized in that step 2) in: reaction pressure is 1.5～2.5MPa.
7. the preparation method of low temperature resistant binary viton as claimed in claim 1 is characterized in that step 2) in: reaction pressure is 1.6～2.4MPa.
8. the preparation method of low temperature resistant binary viton as claimed in claim 1 is characterized in that step 2) in: stir speed (S.S.) is 450～650r/min.
9. the preparation method of low temperature resistant binary viton as claimed in claim 1 is characterized in that: distilled water is by 100 listed as parts by weight, and the weight part of all the other auxiliary agents is respectively: initiator 0.05-0.12, emulsifying agent 0.04-0.70, chain-transfer agent 0.1-1.2.
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| CN107814863A (en) * | 2017-10-19 | 2018-03-20 | 浙江巨圣氟化学有限公司 | A kind of preparation method of low temperature resistant fluorine-containing rubber |
| CN110038503B (en) * | 2018-01-17 | 2020-07-14 | 中昊晨光化工研究院有限公司 | Synthesis process system and method of fluororubber |
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