Separation method of perfluoropolyether lubricating oil

Abstract

The invention belongs to the field of fluorine chemical industry, and particularly relates to a separation method of perfluoropolyether lubricating oil, supercritical extraction equipment is adopted for separation, an extraction agent is carbon dioxide, and an entrainer is one or a mixture of more of hydrofluoroether and a fluorocarbon solvent. According to the technical scheme, the supercritical extraction technology is adopted, the high-molecular-weight perfluoropolyether lubricating oil is extracted and separated in supercritical extraction equipment by taking supercritical carbon dioxide as an extraction agent, meanwhile, an entrainer is introduced, and the perfluoropolyether lubricating oil mixture is separated into products with different molecular weights by adjusting extraction process parameters. The method is simple to operate, high in separation rate and high in yield, the product is easy to separate from the extraction agent and the entrainer, and large-scale production is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of fluorine chemical industry, and in particular relates to a method for separating perfluoropolyether lubricating oil. Background Art

[0002] Perfluoropolyether lubricant is a polymer containing only three elements, C, F, and O, in its molecular chain. It is a colorless and transparent liquid at room temperature. Perfluoropolyether lubricant has excellent thermal stability, chemical inertness, low volatility and other excellent properties, and is widely used in the field of high-end lubricants and greases. In the production process of perfluoropolyether lubricants, a mixture with a wide molecular weight distribution is usually obtained first, and then separated to obtain products with different molecular weights.

[0003] Perfluoropolyether lubricating oil with a molecular weight of <1000 can be obtained by vacuum distillation. When the molecular weight is >1000, vacuum distillation cannot effectively separate the perfluoropolyether lubricating oil product. At this time, molecular distillation equipment can efficiently and conveniently separate perfluoropolyether lubricating oil with a molecular weight of <5000 (Organic Fluorine Industry, 2011 / 38 / 4). The molecular weight of the obtained perfluoropolyether lubricating oil is different depending on the temperature of molecular distillation; however, this method cannot effectively separate perfluoropolyether lubricating oil with a molecular weight of >5000. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for separating perfluoropolyether lubricating oil.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for separating perfluoropolyether lubricating oil adopts supercritical extraction equipment for separation, wherein the extractant is carbon dioxide and the entrainer is one or a mixture of hydrofluoroether and fluorocarbon solvents.

[0007] The average molecular weight of the perfluoropolyether lubricant is greater than 5000, preferably 5000-16000.

[0008] The hydrofluoroether is one of fluoroisobutyl methyl ether and perfluoroisobutyl ethyl ether, or a mixture of at least two of them.

[0009] The fluorocarbon solvent is one of perfluorohexane or perfluoroethyl propyl ether, or a mixture of at least two of them.

[0010] The entraining agent is a mixture of hydrofluoroether and fluorocarbon solvent; the mass ratio of the two is 1:10-2:1; preferably 1:3.

[0011] The flow rate ratio of the entrainer to the extractant is 1:30-1:1, preferably 1:20.

[0012] The supercritical state extraction equipment comprises an extraction tank and a separation tank; the temperature of the extraction tank is 60-70° C.; and the pressure of the extraction tank is set to 10-20 Mpa.

[0013] Preferably, the temperature of the extraction tank is 65° C.; the pressure of the extraction tank is set to 17 MPa.

[0014] The pressure temperature of the separation tank is 2-8Mpa; the temperature of the separation tank is 20-40°C.

[0015] Preferably, the pressure temperature of the separation tank is 5 MPa; the temperature of the separation tank is 30°C.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The technical solution of the present application adopts supercritical extraction technology. In a supercritical extraction device, supercritical carbon dioxide is used as an extractant to extract and separate high molecular weight perfluoropolyether lubricating oil, and an entrainer is introduced at the same time. By adjusting the extraction process parameters, the perfluoropolyether lubricating oil mixture is separated into products of different molecular weights. The method is simple to operate, has a fast separation rate, a high yield, and the product is easy to separate from the extractant and the entrainer, which is convenient for scaled-up production. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with embodiments.

[0019] Example 1

[0020] A method for separating high molecular weight perfluoropolyether lubricating oil comprises the following steps: adding 5 kg of perfluoropolyether lubricating oil with an average molecular weight of 7800 into an extraction tank of a supercritical extraction device, setting the temperature of the extraction tank to 65° C., the pressure of the extraction tank to 17 MPa, the temperature of the separation tank to 30° C., the pressure of the separation tank to 5 MPa, using perfluoroethyl propylene ether as an entrainer, and during the extraction process, the flow rate of the extractant is 20 L / h, and the flow rate of the entrainer is 1 L / h.

[0021] After 6 minutes, 0.25 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 5300; after 25 minutes, 1.00 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 6850; after 65 minutes, 2.75 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 7960; after 43 minutes, 0.85 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 9130; after 10 minutes, no material flowed out from the bottom of the separation tank, and a total of 0.15 kg of product was collected, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 10320.

[0022] Example 2

[0023] A method for separating high molecular weight perfluoropolyether lubricating oil comprises the following steps: adding 5 kg of perfluoropolyether lubricating oil with an average molecular weight of 7800 into an extraction tank of a supercritical extraction device, setting the temperature of the extraction tank to 65° C., setting the pressure of the extraction tank to 17 MPa, setting the temperature of the separation tank to 30° C., setting the pressure of the separation tank to 5 MPa, selecting perfluoroisobutyl ether as an entrainer, and during the extraction process, the flow rate of the extractant is 20 L / h, and the flow rate of the entrainer is 1 L / h.

[0024] After 6 minutes, 0.18 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 4680; after 25 minutes, 0.885 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 5940; after 65 minutes, 2.02 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 7420; after 43 minutes, 1.06 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 8970; after 30 minutes, no material flowed out from the bottom of the separation tank, and a total of 0.855 kg of product was collected, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 9930.

[0025] Example 3

[0026] A method for separating high molecular weight perfluoropolyether lubricating oil comprises the following steps: adding 5 kg of perfluoropolyether lubricating oil with an average molecular weight of 7800 into an extraction tank of a supercritical extraction device, setting the temperature of the extraction tank to 65° C., setting the pressure of the extraction tank to 17 MPa, setting the temperature of the separation tank to 30° C., setting the pressure of the separation tank to 5 MPa, selecting an entrainer as a mixture of perfluoroisobutyl ether ethyl ether and perfluoroethylpropyl ether in a volume ratio of 1:3, and selecting an extractant flow rate of 20 L / h and an entrainer flow rate of 1 L / h during the extraction process.

[0027] After 6 minutes, 0.21 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 4960; after 25 minutes, 0.935 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 6150; after 65 minutes, 2.43 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 7670; after 43 minutes, 0.885 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 9100; after 23 minutes, no material flowed out from the bottom of the separation tank, and a total of 0.54 kg of product was collected, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 10210.

[0028] Example 4

[0029] A method for separating high molecular weight perfluoropolyether lubricating oil comprises the following steps: adding 5 kg of perfluoropolyether lubricating oil with an average molecular weight of 7800 into an extraction tank of a supercritical extraction device, setting the temperature of the extraction tank to 65° C., the pressure of the extraction tank to 17 MPa, the temperature of the separation tank to 30° C., the pressure of the separation tank to 5 MPa, selecting perfluoroethyl propylene ether as an entrainer, and during the extraction process, the flow rate of the extractant is 20 L / h, and the flow rate of the entrainer is 4 L / h.

[0030] After 6 minutes, 0.53 kg of product was collected from the bottom of the separation tank, and after removing the extractant and entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 5860; after 25 minutes, 1.56 kg of product was collected from the bottom of the separation tank, and after removing the extractant and entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 7130; after 58 minutes, no material flowed out of the bottom of the separation tank, and a total of 2.91 kg of product was collected. After removing the extractant and entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 8512.

[0031] Comparative Example 1

[0032] A method for separating high molecular weight perfluoropolyether lubricating oil comprises the following steps: adding 5 kg of perfluoropolyether lubricating oil with an average molecular weight of 7800 into an extraction tank of a supercritical extraction device, setting the extraction tank temperature to 65° C., the extraction tank pressure to 17 MPa, the separation tank temperature to 30° C., the separation tank pressure to 5 MPa, and no entrainer is added. During the extraction process, the flow rate of the extractant is 20 L / h.

[0033] After 6 minutes, 0.135 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 4470; after 25 minutes, 0.66 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 5380; after 65 minutes, 1.58 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 6310; after 43 minutes, 0.84 kg of product was collected from the bottom of the separation tank, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 7520; after 223 minutes, no material flowed out from the bottom of the separation tank, and a total of 1.785 kg of product was collected, and after removing the extractant and the entrainer, nuclear magnetic resonance analysis was performed, and the average molecular weight of the obtained perfluoropolyether lubricant was 10390.

[0034] It can be seen from the results of the embodiment and the comparative example that during the supercritical extraction of perfluoropolyether lubricating oil, as the extraction time changes, the perfluoropolyether lubricating oil mixture can be separated from low to high molecular weight. The addition of an entrainer during the supercritical extraction process can effectively increase the extraction rate, because the addition of the entrainer can reduce the viscosity of the perfluoropolyether lubricating oil and increase its fluidity; however, it can be seen from the results of Example 1 and Example 4 that if too much entrainer is added, the perfluoropolyether lubricating oil mixture cannot be effectively separated; the influence of different types of entrainers on the extraction results mainly comes from the different solvent capacities of different extractants for perfluoropolyether lubricating oil. It can be seen from the comparison of the results of Example 1 and Example 2 that more perfluoropolyether lubricating oil can be separated in Example 1 at the same time interval, and the molecular weight of the separated perfluoropolyether lubricating oil is also higher, which is mainly because perfluoroethylpropyl ether has better solubility for high molecular weight perfluoropolyether lubricating oil than perfluoroisobutyl ether; it can be seen from the results of Example 1 and Example 3 that when a mixed solvent is selected as the entrainer, the separation results of perfluoropolyether lubricating oils of different molecular weights can be achieved without significantly reducing the extraction rate, which is also because the addition of hydrofluoroether in the mixed solvent affects the solubility of the entrainer for the perfluoropolyether lubricating oil.

[0035] In summary, the technical solution of the present application adopts supercritical extraction technology. In a supercritical extraction device, supercritical carbon dioxide is used as an extractant to extract and separate high molecular weight perfluoropolyether lubricating oil, and an entrainer is introduced at the same time. By adjusting the extraction process parameters, the perfluoropolyether lubricating oil mixture is separated into products of different molecular weights. The method is simple to operate, has a fast separation rate, a high yield, and the product is easily separated from the extractant and the entrainer, which is convenient for scaled-up production.

[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for separating perfluoropolyether lubricating oil, characterized in that: Supercritical extraction equipment is used for separation, the extractant is carbon dioxide, and the entrainer is one or a mixture of hydrofluoroether and fluorocarbon solvents.

2. The method for separating perfluoropolyether lubricating oil according to claim 1, characterized in that: The average molecular weight of the perfluoropolyether lubricant is greater than 5000, preferably 5000-16000.

3. The method for separating perfluoropolyether lubricating oil according to claim 1, characterized in that: The hydrofluoroether is one of fluoroisobutyl methyl ether and perfluoroisobutyl ethyl ether, or a mixture of at least two of them.

4. The method for separating perfluoropolyether lubricating oil according to claim 1, characterized in that: The fluorocarbon solvent is one of perfluorohexane or perfluoroethyl propyl ether, or a mixture of at least two of them.

5. The method for separating perfluoropolyether lubricating oil according to claim 1, characterized in that: The entraining agent is a mixture of hydrofluoroether and fluorocarbon solvent; the mass ratio of the two is 1:10-2:1; preferably 1:

3.

6. The method for separating perfluoropolyether lubricating oil according to claim 1, characterized in that: The flow rate ratio of the entrainer to the extractant is 1:30-1:1, preferably 1:

20.

7. The method for separating perfluoropolyether lubricating oil according to claim 1, characterized in that: The supercritical state extraction equipment comprises an extraction tank and a separation tank; the temperature of the extraction tank is 60-70° C.; and the pressure of the extraction tank is set to 10-20 MPa.

8. The method for separating perfluoropolyether lubricating oil according to claim 7, characterized in that: The temperature of the extraction tank is 65° C.; the pressure of the extraction tank is set to 17 MPa.

9. The method for separating perfluoropolyether lubricating oil according to claim 7, characterized in that: The pressure temperature of the separation tank is 2-8Mpa; the temperature of the separation tank is 20-40°C.

10. The method for separating perfluoropolyether lubricating oil according to claim 9, characterized in that: The pressure and temperature of the separation tank is 5 MPa; the temperature of the separation tank is 30°C.