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Polyfluortetraethylene powder and method for producing the same

A technology of polytetrafluoroethylene and its manufacturing method, applied in the field of manufacture of polytetrafluoroethylene fine powder and polytetrafluoroethylene

Active Publication Date: 2011-10-05
DAIKIN IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there is no description of the production method of PTFE by emulsion polymerization, and the obtained polymer is a product that is significantly different from the polymer obtained by emulsion polymerization.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0069] In a 6L horizontal autoclave with a stirrer, 3.55L of pure water (aqueous medium), 54g of ammonium perfluorooctanoate (APFO) in a 10% by mass aqueous solution, 180g of paraffin wax (melting point 62°C), 0.108g of succinic acid ( 30 ppm relative to the aqueous medium), stirring was performed slowly. The inside of the tank was replaced with nitrogen gas while stirring, and then degassed, and the inside of the tank was replaced with TFE gas. The temperature was raised to 80° C., stirred at 200 rpm, the pressure was raised to 2.7 MPa with TFE, and 0.0072 g of ammonium persulfate (APS) (2 ppm relative to the aqueous medium) was added to initiate polymerization. Then, TFE was continuously supplied to keep the pressure inside the tank constant. The stirring speed was set at 135 rpm when 50 g of TFE was consumed, and the stirring speed was set at 120 rpm when 70 g of TFE was consumed. When 3.8 hours had elapsed after the start of the polymerization, the stirring was stopped, ...

Embodiment 2～5 and 7

[0070] Embodiment 2~5 and 7, comparative example 1~4

[0071] Fine powder of PTFE was produced in the same manner as in Example 1 except that the polymerization conditions were changed as shown in Tables 1 and 2. Table 1 shows the standard specific gravity (SSG) of the obtained fine powder and the amount of deposits in the reaction tank.

[0072] In Comparative Example 3, a dispersion was not obtained after the reaction was terminated, and the measurement of the adhesion amount, the solid content concentration as a dispersion, and SSG could not be performed.

Embodiment 6

[0074] Fine powder of PTFE was produced in the same manner as in Example 1 except that the polymerization conditions were changed as shown in Tables 1 and 2. In the polymerization conditions, as for the polymerization pressure, after the initiation of the polymerization, the polymerization was carried out at 0.5 MPa without supplying TFE gas, and the TFE gas was supplied and the pressure was increased to 2.7 MPa after 25 minutes, and then TFE was continuously supplied to thereby The pressure in the tank was kept constant in the same manner as in Example 1.

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Abstract

The invention provides a polytetrafluoroethylene fine powder and a manufacturing method thereof. The polytetrafluoroethylene of the invention can be extruded to shape even in the low extrusion pressure, and the percent thermal shrinkage is small when burning to get the shaping body with excellent strength and flatness. The polytetrafluoroethylene fine powder of the invention has the standard specific gravity (SSG) of lower than 2.160, and the percent thermal shrinkage is lower than 26.0%.

Description

technical field [0001] The invention relates to polytetrafluoroethylene fine powder and a method for producing polytetrafluoroethylene. Background technique [0002] From the viewpoint of excellent moldability, polytetrafluoroethylene (PTFE) preferably requires a low extrusion pressure during extrusion molding and a small heat shrinkage rate when firing the extruded molded product. In addition, strength and smoothness are required for molded products. [0003] As a method for producing PTFE, a method has been proposed in which dicarboxylic acid is added during emulsion polymerization to control or suppress the dimensional change during firing to a preferable value (for example, refer to Patent Document 1). However, in this method, the obtained polymer is a low molecular weight polymer, and the heat shrinkage rate cannot be sufficiently reduced. [0004] As a method for producing PTFE, there is also described a method of reducing the formation of deposits by using a substan...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F114/26C08F2/22B29C47/92B29C48/92
CPCB29C48/92B29C2948/92514B29C2948/92895
Inventor 佐藤洋之泽田又彦
Owner DAIKIN IND LTD