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Method for preparing polyfluortetraethylene dispersion resin

A polytetrafluoroethylene and dispersion resin technology, which is applied in the field of preparation of polytetrafluoroethylene dispersion resin for extruded pipes, can solve the problems affecting product performance and appearance, unstable end group form, unstable polymerization system, etc., and save manpower and hydropower resources, good push extrusion performance, small molecular weight dispersion effect

Active Publication Date: 2011-07-20
ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] CN1986577A discloses adopting ammonium persulfate as initiator to prepare polytetrafluoroethylene dispersion resin for extruding pipes, and its end group form is perfluoro chain-CF 2 -CF 2 -The connected carboxyl end group, the end group form is unstable, and will be partially decomposed during processing, causing small molecules to overflow, and the molecular chain becomes shorter, affecting the performance and appearance of the product
Therefore, in the post-processing process, repeated washing is required to wash away various electrolytes and small molecular substances that may cause terminal group decomposition in the resin, which is labor-intensive and still cannot fully guarantee the appearance of the extruded tube.
[0005] Disclosed in CN10775105A is a kind of production method of high-impact polyacrylate grafted vinyl chloride emulsion copolymerization resin, the effect of composite initiator in this method is to solve the difficult problem that the polymerization system is unstable and the reaction is difficult to control, not for improving the product performance
[0006] CN1253955A discloses and adopts ceric ammonium nitrate / oxalic acid composite initiator to prepare polytetrafluoroethylene dispersion resin, and this product has higher fracture strength and lower creep rate, but does not describe this composite initiator to resin in this patent The impact of extrusion properties, the product resin is mainly used for drawing products, rather than extruded pipe products
However, when the compression ratio exceeds the limit of the resin properties, the extrudate tends to be uneven in appearance, cracks appear on the surface or inside, or the extrudate breaks during extrusion
In addition, from the perspective of equipment, the extrusion pressure cannot be increased excessively during the paste extrusion process, but a high pressure is required to extrude the fine powder under the condition of high compression ratio, which puts high demands on the extruder. requirements, which is not conducive to industrial production

Method used

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  • Method for preparing polyfluortetraethylene dispersion resin

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Effect test

Embodiment 1

[0026] 1. Clean the 50L stainless steel reactor, add 32L of deionized water, 300g of solid paraffin, and 100g of perfluorooctanoic acid ammonium. After sealing the reactor, evacuate it and replace it with nitrogen. If the oxygen content is ≤50ppm, it is qualified. Evacuate, replace it with TFE, and analyze the oxygen content. Content ≤ 30ppm is qualified;

[0027] 2. Then raise the temperature of the reaction kettle to 70±1°C, put in the mixed gas-phase monomer TFE and HFP until the pressure inside the kettle is 2.5MPa, then add 0.15g of ammonium persulfate and 5g of succinic acid peroxide (dissolved in deionized water) ;

[0028] 3. After the reaction starts, continuously add TFE to maintain the pressure in the kettle to be 2.5MPa; when the polymerization reaction is carried out until TFE consumes 20%, add 5g of succinic acid peroxide (dissolved in deionized water) to continue the reaction; Carry out to TFE consumption 40%, add 5g succinic acid peroxide (dissolved in deioniz...

Embodiment 2

[0033] Prepare polytetrafluoroethylene dispersion resin according to the formula of embodiment 1 and preparation steps, difference is: add 0.1g ammonium persulfate, 5g succinic acid peroxide before reaction starts; Add 4g peroxysuccinic acid for the first time; add 6g peroxysuccinic acid for the second time when the polymerization reaction is carried out to TFE consumption 60%.

[0034] The paste extrusion performance of the prepared polytetrafluoroethylene resin was measured, and the results are shown in Table 1.

Embodiment 3

[0036] According to the formula and reaction conditions of Example 2, the difference is: add 0.2g ammonium persulfate and 5g succinic acid peroxide before the reaction begins; add 3g butyl peroxide for the first time when the reaction is carried out until TFE consumes 30% Diacid, add 2g peroxysuccinic acid for the second time after monomer recovery.

[0037] The paste extrusion performance of the prepared polytetrafluoroethylene resin was measured, and the results are shown in Table 1.

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Abstract

The invention provides a method for preparing polyfluortetraethylene dispersion resin. In the method, ammonium persulfate-peroxysuccinic acid is taken as a composite initiator, and polymerized tetrafluoroethylene is dispersed in an aqueous medium; and the ratio of the ammonium persulfate to the peroxysuccinic acid in the composite initiator is 1:(10-200). By adopting the preparation method, under the synergic action of the ammonium persulfate-peroxysuccinic acid serving as the composite initiator, the decomposition rate of the initiator is effectively controlled and compensated, the number of produced free radicals is balanced, chain initiation speed and chain growth speed can be increased, a tetrafluoroethylene polymer with a high molecular weight and low molecular weight dispersity can be obtained, and the obtained resin has high pushing and extruding performance; the reaction speed is temperate, a small quantity of emulsion breaking materials is used in polymerization fluid, and the inner wall of a reaction kettle is clean after discharging at the end of a reaction; and a cleaning process is not required during aftertreatment, so that labor force and hydroelectric resources are saved, cost is saved, product performance is improved, and situations such as yellowing, cracking and the like of an extruding pipe do not exist.

Description

technical field [0001] The invention relates to a preparation method of a polytetrafluoroethylene dispersion resin, in particular to a preparation method of a polytetrafluoroethylene dispersion resin for pipe extrusion using an inorganic-organic composite initiator. Background technique [0002] There are two polymerization processes of polytetrafluoroethylene (PTFE): suspension polymerization and dispersion polymerization. Suspension polymerization resin is milled to obtain fine powder, which shows good fluidity. The main processing method is molding or plunger extrusion; dispersion polymerization emulsion is coagulated and dried to obtain fine powder, which cannot be melt-processed, but it is allowed to form fibers and process A liquid lubricant can be added and then extruded in a paste form. In addition, the dispersion polymerization solution can be stabilized by adding a surfactant, and then concentrated for coating or impregnation. [0003] The polymerization initiato...

Claims

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Application Information

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IPC IPC(8): C08F214/26C08F4/34C08F4/30C08F2/16
Inventor 张建新胡显权姚权卫张春静秦向明苏小龙罗湘华
Owner ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD
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