CN111793151A - Method for monitoring free radical polymerization reaction process on line - Google Patents
Method for monitoring free radical polymerization reaction process on line Download PDFInfo
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- CN111793151A CN111793151A CN202010679389.2A CN202010679389A CN111793151A CN 111793151 A CN111793151 A CN 111793151A CN 202010679389 A CN202010679389 A CN 202010679389A CN 111793151 A CN111793151 A CN 111793151A
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- radical polymerization
- polymerization reaction
- free radical
- molecular weight
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2400/00—Characteristics for processes of polymerization
- C08F2400/02—Control or adjustment of polymerization parameters
Abstract
The invention provides a method for monitoring a free radical polymerization reaction process on line, belonging to the technical field of polymerization reaction process monitoring. The method for monitoring the free radical polymerization reaction process on line provided by the invention comprises the following steps: the preparation method comprises the steps of placing a preparation raw material of a target polymer into a reactor for free radical polymerization reaction, connecting a sampling port of the reactor with a gel permeation chromatograph, sampling through the sampling port in the free radical polymerization reaction process, and detecting the molecular weight of a sample by using the gel permeation chromatograph so as to monitor the free radical polymerization reaction process. In the method provided by the invention, the gel permeation chromatograph can be used for accurately and quickly measuring the molecular weight of the sample, has strong continuity, can be widely applied to the production of polymers based on free radical polymerization, can well monitor the process of the free radical polymerization reaction, enables the reaction to stay at an ideal reaction degree, effectively reduces the occurrence of side reactions, and improves the yield of target polymers.
Description
Technical Field
The invention relates to the technical field of polymerization reaction process monitoring, in particular to a method for monitoring a free radical polymerization reaction process on line.
Background
The radical polymerization is a chemical reaction in which a monomer molecule is activated into an active radical by the action of light, heat, radiation, an initiator or the like, and then the active radical is polymerized in a chain with the monomer to form a high polymer. Free radical polymerization plays an extremely important role in polymer chemistry, is a polymerization reaction which is the earliest and the best research of human development, and more than 60 percent of polymers are obtained by free radical polymerization, such as low-density polyethylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and the like.
The free radical polymerization belongs to chain polymerization and is divided into four elementary reactions of chain initiation, chain growth, chain termination and chain transfer. However, the progress of many radical polymerization reactions is often difficult to control, which may lead to insufficient or excessive reaction, resulting in increased side reactions and a decrease in yield of the desired product. Therefore, it is important to monitor the progress of the radical polymerization reaction.
Disclosure of Invention
The invention aims to provide a method for monitoring the process of free radical polymerization reaction on line, which can be widely applied to the production of polymers based on free radical polymerization, can well monitor the process of the free radical polymerization reaction, enables the reaction to stay at an ideal reaction degree, effectively reduces the occurrence of side reactions and improves the yield of target polymers.
In order to achieve the above object, the present invention provides the following technical solutions:
a method for monitoring the progress of free radical polymerization reaction on line comprises the following steps:
the preparation method comprises the steps of placing a preparation raw material of a target polymer into a reactor for free radical polymerization reaction, connecting a sampling port of the reactor with a gel permeation chromatograph, sampling through the sampling port in the free radical polymerization reaction process, and detecting the molecular weight of a sampled product by using the gel permeation chromatograph so as to monitor the free radical polymerization reaction process.
Preferably, the target polymer comprises one of low density polyethylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, styrene butadiene rubber, nitrile butadiene rubber, and chloroprene rubber.
Preferably, the interval time between two adjacent samples in the process of the free radical polymerization reaction is more than or equal to 10 min.
Preferably, in the process of the free radical polymerization reaction, the interval time between two adjacent samples is 20-60 min.
Preferably, the time for initial sampling is 50% or more of the total reaction time, based on the start of the radical polymerization reaction.
Preferably, the time for the first sampling is 60 to 80% of the total reaction time, based on the start of the radical polymerization reaction.
Preferably, the method further comprises the following steps after the gel permeation chromatograph is used for detecting the molecular weight of the sample: if the molecular weight of the sample does not reach the molecular weight of the target polymer, continuing the free radical polymerization reaction; and stopping the free radical polymerization reaction if the molecular weight of the sample reaches the molecular weight of the target polymer.
The invention provides a method for monitoring the process of free radical polymerization reaction on line, which comprises the following steps: the preparation method comprises the steps of placing a preparation raw material of a target polymer into a reactor for free radical polymerization reaction, connecting a sampling port of the reactor with a gel permeation chromatograph, sampling through the sampling port in the free radical polymerization reaction process, and detecting the molecular weight of a sampled product by using the gel permeation chromatograph so as to monitor the free radical polymerization reaction process. In the method provided by the invention, the gel permeation chromatograph can be used for accurately and quickly measuring the molecular weight of the sample, has strong continuity, can be widely applied to the production of polymers based on free radical polymerization, can well monitor the process of the free radical polymerization reaction, enables the reaction to stay at an ideal reaction degree, effectively reduces the occurrence of side reactions, and improves the yield of target polymers.
Drawings
FIG. 1 is a schematic flow diagram of a method for on-line monitoring of a free radical polymerization process in accordance with the present invention;
FIG. 2 is a graph showing the molecular weight distribution of the target polymer in example 1;
FIG. 3 is a graph showing the molecular weight distribution of the target polymer in example 2.
Detailed Description
The invention provides a method for monitoring the process of free radical polymerization reaction on line, which comprises the following steps:
the preparation method comprises the steps of placing a preparation raw material of a target polymer into a reactor for free radical polymerization reaction, connecting a sampling port of the reactor with a gel permeation chromatograph, sampling through the sampling port in the free radical polymerization reaction process, and detecting the molecular weight of a sampled product by using the gel permeation chromatograph so as to monitor the free radical polymerization reaction process.
The specific type of the target polymer is not particularly limited in the present invention, and any polymer obtained by radical polymerization may be used. In the present invention, the target polymer preferably includes one of low density polyethylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, styrene-butadiene rubber, nitrile rubber, and chloroprene rubber.
The reactor and the gel permeation chromatograph are not particularly limited in the present invention, and a reactor known to those skilled in the art may be used. The invention has no special requirements on the specific connection mode of the sampling port of the reactor and the gel permeation chromatograph, and ensures that the sample taken out from the sampling port can be smoothly and quickly analyzed by the gel permeation chromatograph.
The raw materials for preparing the target polymer and the conditions for the free radical polymerization reaction are not particularly limited and can be selected according to actual needs.
The method preferably performs preliminary prediction on the reaction time of the free radical polymerization reaction according to a synthesis mechanism, and determines the time of primary sampling according to the predicted reaction time; specifically, the time for initial sampling is preferably 50% or more, more preferably 60 to 80% of the total reaction time, based on the start of the radical polymerization reaction.
In the invention, in the process of the free radical polymerization reaction, the interval time between two adjacent samplings is preferably not less than 10min, more preferably 20-60 min, the specific interval time is selected according to the intensity of the free radical polymerization reaction, and if the free radical polymerization reaction is predicted to be more intense and the reaction time is shorter according to the synthesis mechanism, the interval time is shorter; if the free radical polymerization reaction is slow and the reaction time is long, the interval time is long.
The invention has no special limitation on the detection condition when the gel permeation chromatograph is used for detecting the molecular weight of the sampled product, and the detection condition can be selected according to the actual requirement.
In the invention, after the gel permeation chromatograph is used for detecting the molecular weight of a sample, if the molecular weight of the sample does not reach the molecular weight of a target polymer, the free radical polymerization reaction is continued; and if the molecular weight of the sample reaches the molecular weight of the target polymer, stopping the free radical polymerization reaction, and discharging.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
According to the schematic flow chart shown in FIG. 1, the polymer A is produced by using the monomer a, and the molecular weight of the product in the production process is monitored, so that the reaction process is monitored, and the method comprises the following steps:
placing a reaction raw material containing a monomer a into a reactor for free radical polymerization reaction, wherein a sampling port of the reactor is connected with a gel permeation chromatograph, predicting the molecular weight of a target polymer to be 17000-18000 g/mol according to a synthesis mechanism, wherein the reaction time is 2-3 hours, and the reaction is violent, so that the sampling is carried out once every 20 minutes from 90 minutes, and the molecular weight of a sample is detected on line by using the gel permeation chromatograph; the progress of the radical polymerization reaction is deduced from the molecular weight of the sample.
The molecular weights of the samples for different reaction times during the preparation of polymer a are shown in fig. 2 and table 1.
TABLE 1 molecular weight of samples corresponding to different reaction times during the preparation of Polymer A
| Reaction time (min) | 90 | 110 | 130 | 150 | 170 | 190 |
| Molecular weight (g/mol) | 3123 | 3192 | 7289 | 11897 | 17230 | 17319 |
As is clear from Table 1, the radical polymerization reaction was stopped and the product was discharged at 170 to 190 minutes, since the degree of radical polymerization was almost satisfactory.
Example 2
According to the schematic flow chart shown in FIG. 1, the process of the reaction is monitored by using the monomer B to produce the polymer B and monitoring the molecular weight of the product in the production process, and the process comprises the following steps:
placing a reaction raw material containing a monomer b into a reactor for free radical polymerization reaction, wherein a sampling port of the reactor is connected with a gel permeation chromatograph, predicting the molecular weight of a target polymer to be 60000-62000 g/mol according to a synthesis mechanism, wherein the reaction time is longer than 15 hours, and the reaction is slow, so that sampling is performed once every 1 hour from 9 hours, and the molecular weight of a sample is detected on line by using the gel permeation chromatograph; the progress of the radical polymerization reaction is deduced from the molecular weight of the sample.
The molecular weights of the samples for different reaction times during the preparation of polymer B are shown in fig. 3 and table 2.
TABLE 2 molecular weights of samples corresponding to different reaction times in the preparation of Polymer B
| Reaction time (min) | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| Molecular weight (g/mol) | 15113 | 26370 | 37502 | 51896 | 52373 | 56912 | 61280 | 61673 |
As is clear from Table 2, the radical polymerization reaction was stopped and the product was discharged after 15 hours since the radical polymerization reaction almost reached the desired level.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A method for monitoring the progress of free radical polymerization reaction on line is characterized by comprising the following steps:
the preparation method comprises the steps of placing a preparation raw material of a target polymer into a reactor for free radical polymerization reaction, connecting a sampling port of the reactor with a gel permeation chromatograph, sampling through the sampling port in the free radical polymerization reaction process, and detecting the molecular weight of a sampled product by using the gel permeation chromatograph so as to monitor the free radical polymerization reaction process.
2. The method of claim 1, wherein the target polymer comprises one of low density polyethylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, styrene butadiene rubber, nitrile butadiene rubber, and neoprene.
3. The method as claimed in claim 1, wherein the interval between two adjacent samples during the free radical polymerization reaction is not less than 10 min.
4. The method according to claim 3, wherein the interval between two adjacent samples in the process of the free radical polymerization is 20-60 min.
5. The method according to claim 3 or 4, wherein the time for initial sampling is 50% or more of the total reaction time based on the start of the radical polymerization reaction.
6. The method according to claim 5, wherein the initial sampling time is 60 to 80% of the total reaction time based on the start of the radical polymerization reaction.
7. The method of any one of claims 1 to 6, wherein the step of detecting the molecular weight of the sample by the gel permeation chromatograph further comprises: if the molecular weight of the sample does not reach the molecular weight of the target polymer, continuing the free radical polymerization reaction; and stopping the free radical polymerization reaction if the molecular weight of the sample reaches the molecular weight of the target polymer.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1056882A (en) * | 1990-05-14 | 1991-12-11 | 国际壳牌研究有限公司 | Termination of anionic polymerization using hydrogen |
| CN101939031A (en) * | 2008-02-06 | 2011-01-05 | 威士伯采购公司 | Process for manufacturing medium and high molecular weight polyesters |
| WO2011054191A1 (en) * | 2009-11-09 | 2011-05-12 | 浙江杭州鑫富药业股份有限公司 | Aliphatic-aromatic copolyester, preparation method and applications thereof |
| CN107003220A (en) * | 2014-10-01 | 2017-08-01 | 先进的聚合物监测技术股份有限公司 | Control for polymer reaction and the system and method using the processing automatically continuously monitored on-line |
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- 2020-07-15 CN CN202010679389.2A patent/CN111793151A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1056882A (en) * | 1990-05-14 | 1991-12-11 | 国际壳牌研究有限公司 | Termination of anionic polymerization using hydrogen |
| CN101939031A (en) * | 2008-02-06 | 2011-01-05 | 威士伯采购公司 | Process for manufacturing medium and high molecular weight polyesters |
| WO2011054191A1 (en) * | 2009-11-09 | 2011-05-12 | 浙江杭州鑫富药业股份有限公司 | Aliphatic-aromatic copolyester, preparation method and applications thereof |
| CN107003220A (en) * | 2014-10-01 | 2017-08-01 | 先进的聚合物监测技术股份有限公司 | Control for polymer reaction and the system and method using the processing automatically continuously monitored on-line |
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Application publication date: 20201020 |