A kind of coagulation method of polytetrafluoroethylene dispersed resin

A technology of polytetrafluoroethylene and coagulation method, applied in the field of polymerization of polytetrafluoroethylene emulsion, can solve the problems of decreased cohesion strength, influence on processing process, wide particle size range, etc., to increase cohesion strength, reduce damage probability, The effect of improving production efficiency

Active Publication Date: 2018-09-11
ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the coagulation process, due to the difference between the emulsion temperature and the ambient temperature, the temperature of the emulsion often changes during the coagulation process, resulting in the agglomeration of particles in the resin, resulting in a large amount of micropowder composition, and the particle size range of the resin is wide, which affects the post-processing process.
[0004] Patent CN103124763A discloses a manufacturing method of polytetrafluoroethylene fine powder, which is characterized in that in the coagulation process, a surfactant is added, and a special agitator is used for the coagulation process, and the obtained resin is easy to form and process, which solves the problem of oversized particles. However, due to the special shape of the agitator used in the coagulation process, the coagulation strength decreases, the coagulation time is prolonged, the temperature of the emulsion changes during the process, the composition of the micropowder is large, and the particle size range of the resin is large. The stability of the product in the process has a great influence
[0005] Patent CN1942493A discloses a preparation method of modified polytetrafluoroethylene, which is characterized in that tetrafluoroethylene monomers are polymerized with olefinic comonomers, and the obtained copolymer emulsion is diluted to 15%, and dispersed by strong mechanical stirring. Resin, although the resin has been modified and the compression ratio has been increased, the coagulation temperature has not been effectively controlled during the coagulation process, and there is a micropowder composition in the resin with a wide particle size range, which has a great impact on the stability of the processed product
[0006] Patent CN101215347A discloses a polytetrafluoroethylene production method for processing wide-width oil-free low-density raw material tapes, which is characterized in that under certain process conditions, polytetrafluoroethylene dispersion resin emulsion is obtained by homopolymerization of tetrafluoroethylene, and after In the late coagulation and drying process, the product obtained has high elongation and is suitable for making raw material tapes. However, in the coagulation process, there is no mention of temperature control. The coagulation obtained resin is composed of fine powder, and the particle size range of the resin is wide. The stability of processed products has a great influence

Method used

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  • A kind of coagulation method of polytetrafluoroethylene dispersed resin
  • A kind of coagulation method of polytetrafluoroethylene dispersed resin

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] see figure 1 and figure 2 , the equipment used for coagulation has a cylindrical shell, and a cuboid-shaped coagulation barrel 2 is placed in the cylindrical shell, and the space between the cylindrical shell and the coagulation barrel is a jacket 1 for feeding a cooling medium; an agitator is arranged in the coagulation barrel 2 , the stirrer is provided with two layers of 3; the angle between the adjacent stirring blades 3 of each layer is 90 °, and the angle between the stirring blades 3 and the horizontal plane is 45 ° (see figure 2 ), the two layers of stirring blades are inclined in the same direction. The stirring shaft 4 is connected to a reducer, and the reducer is connected to a motor 5 . In this embodiment, the motor 5 is located under the coagulation bucket 2 .

[0030] The cross-sectional shape of the condensation bucket 2 is a square, and the ratio of the height of the condensation bucket to the side length of the square is 1.2:1. The four corners of ...

Embodiment 2

[0035] The equipment is the same as in Example 1, the difference in operation is: dilute to a solid content of 12%, and control the temperature to 17°C, control the volume of the emulsion to 850L, and use the jacket temperature control system to keep the temperature of the material in the coagulation tank at 17°C , add 1.35kg of ammonium carbonate, the agitator control speed is 140 rpm, when the coagulation time reaches 30 minutes, close the agitator to complete the coagulation process of the emulsion, and the obtained material is carried out in the drying stage.

[0036] The average particle size of the resin after drying is 501 μm, the minimum particle size is 220 μm, and the maximum particle size is 832 μm.

Embodiment 3

[0038] The equipment is the same as in Example 1, the difference in operation is: dilute to a solid content of 10%, and control the temperature to 19°C, control the volume of the emulsion to 750L, and use the jacket temperature control system to keep the temperature of the material in the coagulation tank at 19°C. ℃, add 1.35kg of ammonium carbonate, the agitator control speed is 180 rpm, when the coagulation time reaches 25 minutes, close the agitator to complete the coagulation process of the emulsion, and the obtained material goes to the drying stage.

[0039] The average particle size of the resin after drying is 572 μm, the minimum particle size is 290 μm, and the maximum particle size is 902 μm.

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Abstract

The invention belongs to the field of organic high molecular compounds and provides an agglomeration method of polytetrafluoroethylene dispersed resin. The method includes the steps of: diluting polytetrafluoroethylene polymerized emulsion by means of deionized water, and placing the diluted emulsion into an agglomeration barrel; controlling the agglomeration temperature at 15-20 DEG C and maintaining the temperature of the emulsion to be constant during agglomeration, adding an electrolyte being ammonium carbonate or ammonium bicarbonate, and performing the agglomeration under stirring status. Through the novel agglomeration device, the temperature is relatively maintained to be stable within agglomeration time, so that the influence on resin particle size and agglomeration phenomenon due to temperature change is reduced. Meanwhile, by changing the shape of the inner wall of the agglomeration barrel from a common round shape or quincunx shape having a baffle into a square-like shape, agglomeration intensity during agglomeration is improved and damage on the resin particles due to the baffle is reduced, thereby alleviating aggregation of the particles; through reasonable setting of agglomeration rotation speed and addition amount of the electrolyte, agglomeration time is reduced, production efficiency is improved and damage possibility of the resin particles is reduced.

Description

technical field [0001] The invention belongs to the field of organic polymer compounds, and in particular relates to a polytetrafluoroethylene emulsion polymerization method. Background technique [0002] Due to its excellent comprehensive properties, such as high and low temperature resistance, insulation performance, low friction coefficient, corrosion resistance, aging resistance, non-stickiness, etc., PTFE is widely used in aerospace, machinery manufacturing, chemical, medical, electronic appliances, etc. field. There are two kinds of tetrafluoroethylene polymerization processes: suspension polymerization and dispersion polymerization, and the obtained resins are suspension resin and dispersion resin respectively. Dispersed polytetrafluoroethylene resin undergoes a post-treatment process, with strong mechanical agitation for emulsion coagulation and demulsification, and drying to obtain a dispersed resin. [0003] In the post-treatment coagulation process, the commonly...

Claims

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Application Information

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Patent Type & AuthorityPatents(China)
IPC IPC(8): C08F6/22C08F14/26
Inventor姚权卫
OwnerZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD