Embodiment
The method of the synthetic polyvinylidene difluoride (PVDF) of the present invention adopts carbonic acid gas as reaction medium.Described polymerization is at 10-35MPa, at 40-80 ℃, carries out under preferred 50-70 ℃ the temperature under the pressure of preferred 20-30MPa.
Under pressure and temperature condition of the present invention, carbonic acid gas is supercritical state.At this moment, its physical properties is between gas and liquid.Adopt carbonic acid gas to make solvent, can reduce environmental pollution, obtain more purified polymer, aftertreatment is simple.And the carbonic acid gas low price helps product performance and environmental protection.
Polymerization process of the present invention uses the peroxy dicarbonate dialkyl as initiator.Term " alkyl " is meant and has 1-12 carbon atom in the present invention, better the straight or branched saturated hydrocarbyl of 1-6 carbon atom.Its indefiniteness example has methyl, ethyl, n-propyl, sec.-propyl, normal-butyl, isobutyl-, the tertiary butyl, amyl group, hexyl etc.
The indefiniteness example that is applicable to initiator of the present invention has peroxy dicarbonate dimethyl ester, peroxy dicarbonate diethyl ester, di-isopropyl peroxydicarbonate, peroxy dicarbonate dibutylester, peroxy dicarbonate di tert butyl carbonate etc., is preferably di-isopropyl peroxydicarbonate ((CH
3)
2CH-O-CO-O-O-CO-OCH (CH
3)
2) (being called for short IPP) and peroxy dicarbonate diethyl ester.Be applicable to that initiator of the present invention is that a class transformation period is very short, can be at the peroxy dicarbonates initiator of initiated polymerization under the lower temperature.
Can adopt initiator solution during use.The solvent that is used to prepare initiator solution is without particular limitation, as long as it does not influence polyreaction.In a better example of the present invention, the described solvent that is used to prepare initiator solution is selected from Chlorofluorocarbons (CFCs) (as CCl
2FCClF
2(be called for short CFC-113)), Hydrochlorofluorocarbons and hydrogen fluorohydrocarbon (as 1,1,1,3, the 3-3-pentafluorobutane), better be Hydrochlorofluorocarbons and hydrogen fluorohydrocarbon, because this type of material can not damage the ozone layer.
In concentration expressed in percentage by weight, the concentration of initiator solution is generally 52wt%.Initiator solution generally places-10 ℃ to preserve down.And when polymerization, add in the reaction system with solvent cut as the case may be.
The reaction medium that is applicable to polyreaction of the present invention is the carbonic acid gas of food grade, and its purity reaches 99.995%.Generally do not need further processing.
Monomer can be available from Shanghai Sanaifu New Material Co., Ltd to be applicable to vinylidene of the present invention (being called for short VDF), and purity reaches 99.990%.
In a better example of the present invention, with molar concentration meter, the consumption of initiator is 0.0005-0.05mol/L, preferred 0.001-0.01mol/L.
In a better example of the present invention, the solvent of initiator solution (CFC-113) concentration is 0.04-0.8mol/L, preferred 0.08-0.4mol/L.
In a better example of the present invention.Monomer concentration is 2-12mol/L, preferred 4-8mol/L.
In a better example of the present invention, the consumption of carbonic acid gas is 6-22mol/L in the reaction system, preferred 12-18mol/L.
The inventive method can be taked once to feed intake and fed batch repeatedly, once advances initiator and repeatedly advances initiator in batches.
Polymerization process of the present invention only adopts above-mentioned raw material and solvent.Its primary solvent carbonic acid gas is nontoxic, does not explode, and is cheap, environmental protection, highly volatile.Contain the solvent of a small amount of initiator and dissolving initiator in the final product, can from product, extract these materials, improve the purity of product with carbonic acid gas.In addition, it is big to adopt the inventive method to obtain molecular weight, the bussiness class product that mechanical strength is good.
The present invention also provides a kind of polyvinylidene difluoride (PVDF), and its number-average molecular weight is 65,000-241, and 000, weight-average molecular weight is 91,000-400,000.The foreign matter content that it is characterized in that described polyvinylidene difluoride (PVDF) is less than 0.22% (mol/mol).
The present invention also provides a kind of polyvinylidene difluoride (PVDF) goods, and it comprises that content is higher than 99.78mol%, better is higher than the polyvinylidene difluoride (PVDF) of 99.81mol%.
In a better example of the present invention, the tensile strength of described polyvinylidene difluoride (PVDF) is 37-45MPa.
In another example of the present invention, the elongation at break of described polyvinylidene difluoride (PVDF) is 25-30%.
In another example of the present invention, the thermal weight loss critical temperature of described polyvinylidene difluoride (PVDF) is 470-472 ℃.
Below, further specify the present invention in conjunction with the embodiments.
Embodiment
Test method
The performance of the polyvinylidene difluoride (PVDF) that suitable following method test the inventive method makes:
Tensile strength and elongation at break test
Be suitable for Britain LLOYD INSTRUMENTS LR5K plus.According to GB: GB/T 1040-92 test.
The molecular weight test
[100 μ L sample introduction posts in Perkin Elmer Series-200 system, PL gel (10 μ m) 300mm * 7.5mm mixed-B chromatographic column, polystyrene is proofreaied and correct], measure polymericular weight by gel permeation chromatography (GPC), probe temperature is 70 ℃, DMF is a solvent, and flow velocity is 1.0mL/min.
The thermal weight loss test
Perkin Elmer TGA 7, nitrogen protection, heat-up rate is 20 ℃/min, scope is a room temperature to 800 ℃.
The foreign matter content test
With
1The content of H NMR test products impurity, nuclear magnetic resonance spectroscopy carries out on Bruker av400 nuclear magnetic resonance analyser, 50 ℃ of temperature, DMSO-d
6Be solvent.Chemical shift 2.8-3.3 is a PVDF sequential structure end to end, and contrary head-to-tail structure is represented at the peak at 2.4 places, and 4.5 and 5.0 is end group peaks, and 1.4 places are that end group is the end group peak of initiator group, and near the peak it is considered impurity peaks.With the integral area at peak herein sum total, obtain the molar content of impurity divided by all peaks.
Embodiment 1
Earlier reaction unit and feeding unit air are drained, then with after the VDF cooling, add 1 liter of reactor by fresh feed pump, inlet amount is about 350 grams, about 5.5 moles, add carbonic acid gas to certain pressure, be warming up to 55 ℃ then, continue to add carbonic acid gas, stagnation pressure is 27MPa to the still, open stirring, rotating speed is 450 rev/mins.Add 25 milliliters of CFC-113 solution that contain initiator, contain 0.0045 mole of initiator (IPP), reacted 2 hours.Stop after reaction finishes to stir, logical water coolant left standstill 20 minutes, and product is collected in venting.Productive rate 15%.Product is particulate state, and particle diameter is 0.5-1mm.(GPC) records number-average molecular weight 134000g/mol with gel permeation chromatography, and weight-average molecular weight is 317000g/mol.
Use aforesaid method to measure product performance, the results are shown in following table.
Embodiment 2
Earlier reaction unit and feeding unit air are drained, then with after the VDF cooling, add 1 liter of reactor by fresh feed pump, inlet amount is about 300 grams, about 4.7 moles, add carbonic acid gas to certain pressure, be warming up to 55 ℃ then, continue to add carbonic acid gas, stagnation pressure is 27MPa to the still, open stirring, rotating speed is 300 rev/mins.The real reaction temperature is controlled at 58 ℃.Add 8 milliliters of CFC-113 solution that contain initiator earlier, add 10 milliliters after 20 minutes, containing initiator (IPP) total amount is 0.003 mole, and reaction total time is 2 hours.Stop after reaction finishes to stir, logical water coolant left standstill 20 minutes, and product is collected in venting.Productive rate 12%.Product is particulate state, and particle diameter is 0.5-2mm.(GPC) records number-average molecular weight 241000g/mol with gel permeation chromatography, and weight-average molecular weight is 400000g/mol.
Use aforesaid method to measure product performance, the results are shown in following table 1.
Table 1
Embodiment | Number-average molecular weight Mn (g/mol) | Weight-average molecular weight Mw (g/mol) | Tensile strength MPa | Elongation at break % | Thermal weight loss critical temperature ℃ | Foreign matter content (mole %) |
1 | 134000 | 317000 | 37.8 | 25 | 471.88 | 0.2169 |
2 | 241000 | 400000 | 44.2 | 30 | 471.4 | 0.1857 |
Embodiment 3
Earlier reaction unit and feeding unit air are drained, with after the VDF cooling, add 1 liter of reactor then by fresh feed pump, inlet amount is about 200 grams, about 3.125 moles, adds carbonic acid gas to pressure 10MPa, be warming up to 60 ℃ then, open stirring, rotating speed is 600 rev/mins.Add 18 milliliters of CFC-113 solution that contain initiator, contain 0.003 mole of initiator (IPP), reacted 2 hours.Stop after reaction finishes to stir, logical water coolant left standstill 20 minutes, and product is collected in venting.Productive rate 15%.Product is a white powder.(GPC) records number-average molecular weight 65000g/mol with gel permeation chromatography, and weight-average molecular weight is 91000g/mol.
Embodiment 4
Earlier reaction unit and feeding unit air are drained, with after the VDF cooling, add 1 liter of reactor then by fresh feed pump, inlet amount is about 200 grams, about 3.125 moles, adds carbonic acid gas to pressure 30MPa, be warming up to 40 ℃ then, open stirring, rotating speed is 600 rev/mins.Add 20 milliliters of CFC-113 solution that contain initiator, contain 0.01 mole of initiator (peroxy dicarbonate diethyl ester), reacted 2 hours.Stop after reaction finishes to stir, logical water coolant left standstill 20 minutes, and product is collected in venting.Productive rate 15%.Product is a white powder.(GPC) records number-average molecular weight 66000g/mol with gel permeation chromatography, and weight-average molecular weight is 92000g/mol.
Embodiment 5
Earlier reaction unit and feeding unit air are drained, with after the VDF cooling, add 1 liter of reactor then by fresh feed pump, inlet amount is about 200 grams, about 3.125 moles, adds carbonic acid gas to pressure 35MPa, be warming up to 70 ℃ then, open stirring, rotating speed is 600 rev/mins.Add 18 milliliters of CFC-113 solution that contain initiator, contain 0.001 mole of initiator (peroxy dicarbonate dimethyl ester), reacted 2 hours.Stop after reaction finishes to stir, logical water coolant left standstill 20 minutes, and product is collected in venting.Productive rate 15%.Product is a white powder.(GPC) records number-average molecular weight 200500g/mol with gel permeation chromatography, and weight-average molecular weight is 350000g/mol.
Embodiment 6
Earlier reaction unit and feeding unit air are drained, with after the VDF cooling, add 1 liter of reactor then by fresh feed pump, inlet amount is about 200 grams, about 3.125 moles, adds carbonic acid gas to pressure 20MPa, be warming up to 80 ℃ then, open stirring, rotating speed is 600 rev/mins.Add 18 milliliters of CFC-113 solution that contain initiator, contain 0.0009 mole of initiator (peroxy dicarbonate di tert butyl carbonate), reacted 2 hours.Stop after reaction finishes to stir, logical water coolant left standstill 20 minutes, and product is collected in venting.Productive rate 15%.Product is a white powder.(GPC) records number-average molecular weight 65000g/mol with gel permeation chromatography, and weight-average molecular weight is 91000g/mol.