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Polytetrafluoroethylene molded articles coated with fused fluoropolymer resin

a technology of fused fluoropolymer and polytetrafluoroethylene, which is applied in the direction of synthetic resin layered products, coatings, transportation and packaging, etc., can solve the problem of insufficient smooth surface of ptfe molded articles, and achieve the effect of reducing roughness

Inactive Publication Date: 2005-05-19
NISHIO TAKAO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a way to make a smoother surface on a molded article of polytetrafluoroethylene or modified polytetrafluoroethylene. This is done by coating the article with a heat-flowable fluoropolymer powder resin and heating it to form a fused resin coating. The surface of the coated article is much smoother than the uncoated article. This technique can be used to create a smooth surface on a variety of polytetrafluoroethylene-based materials."

Problems solved by technology

However, generally, the surface of PTFE molded articles is not sufficiently smooth.
This is a cause for concern when such articles are used as containers for high purity chemicals or linings for transport pipes, since contaminants tend to adhere to the surface and are difficult to remove even after attempts are made to clean the articles.

Method used

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  • Polytetrafluoroethylene molded articles coated with fused fluoropolymer resin
  • Polytetrafluoroethylene molded articles coated with fused fluoropolymer resin
  • Polytetrafluoroethylene molded articles coated with fused fluoropolymer resin

Examples

Experimental program
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Effect test

examples

[0025] The present invention is now more specifically described using the examples below. The compositions, physical properties, and manufacturing processes and the like, of the fluoropolymer resins used as substrates and as coatings in these examples and comparative examples are given below.

Fluoropolymer Resins

[0026] (1) PTFE Powder: [0027] Average Particle Size 301 μm [0028]“Teflon 170-J” (Registered trademark, Mitsui DuPont [0029] Fluorochemicals KK)

[0030] (2) PFA Powder: [0031] Average Particle Size 28 μm [0032] Manufactured by Mitsui DuPont Fluorochemicals KK [0033] Copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether) (PFA) [0034] [perfluoro(propyl vinyl ether) content 3.6 wt %]

[0035] (3) FEP Powder: [0036] Average Particle Size 32 μm [0037] Manufactured by Mitsui DuPont Fluorochemicals KK [0038] Copolymer of tetrafluoroethylene and hexafluoropropylene [0039] (FEP) [hexafluoropropylene content 12.0 wt %]

[0040] (4) Low Molecular Weight PTFE Powder [0041] Averag...

examples 1 and 2

[0050] A heat-flowable fluoropolymer resin of PFA (2) or FEP (3) powder, as indicated in Table 1, is electrostatically spray coated onto a molded PTFE sheet prepared as described above. The sheet is grounded, 25 cm away. Coating is conducted at an electrical voltage of 10 kV (negative) and a rate of discharge of 50 mg / min using an electrostatic powder coater (manufactured by Onoda Cement KK; GX-200T) and an electrostatic powder coating gun (Onoda Cement KK GX-107). The applied powder weight is uniformly 2.2 g, thereby generating a 100 μm coated thickness after sintering. The coating environment is at a temperature 25° C. and a moisture level of 60% RH. The coated PTFE sheet is sintered in a forced air circulation oven at 370° C. for 30 minutes and then cooled to room temperature producing a molded PTFE article coated with fused fluoropolymer resin of heat-flowable PFA or FEP.

[0051] The center line average roughness (Ra) of the surface of the resulting fused fluoropolymer coated PTF...

example 3

[0052] A molded PTFE sheet prepared as described above is electrostatically powder coated in a manner similar to that of Example 1. However, in this example the powder is a mixture of 99% by weight of the PFA powder (2) and 1% of a low molecular weight PTFE powder (4) having a temperature of crystallization of at least 305° C. and heat of crystallization of at least 50 J / g, thereby obtaining a fused fluoropolymer resin coated PTFE sheet.

[0053] Center line average roughness of the surface of the resultant PTFE sheet coated with a PFA containing a low molecular weight PTFE is measured using a laser type three dimensional surface roughness measurement instrument. The results are given in Table 1. A three-dimensional profile obtained using this apparatus is shown in FIG. 1.

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Abstract

The present invention relates to a molded article of polytetrafluoroethylene or modified polytetrafluoroethylene having a fluoropolymer resin coating, the coating comprising a heat-flowable tetrafluoroethylene copolymer wherein the surface of the coated article has a reduced roughness compared to the molded article prior to coating. The coating for the molded article is preferably a fused powder, most preferably formed by electrostatically applying a fluoropolymer powder resin to the molded PTFE article. In a preferred embodiment, the fluoropolymer powder resin comprises a mixture of heat-flowable tetrafluoroethylene copolymer powder and a polytetrafluoroethylene that has a temperature of crystallization of at least 305° C. and a heat of crystallization of at least 50 J / g. The surfaces of the articles are smoother than the original articles so that they resist adhesion of chemical contaminants and have applicability for chemical containers and transport pipes in the rigorously clean environment of the semiconductor industry.

Description

FIELD OF INVENTION [0001] The present invention relates to molded PTFE articles for use as containers for high purity chemicals, typically in the area of semiconductor manufacturing, or as a lining material for transport pipes. BACKGROUND OF THE INVENTION [0002] Because of the excellent heat and chemical resistance of polytetrafluoroethylene (hereafter PTFE) and modified polytetrafluoroethylene, articles formed from these polymers are extensively used in transport pipes that handle corrosive or high temperature fluids or as corrosion resistant lining material for tanks, machines, equipment, and the like. [0003] However, generally, the surface of PTFE molded articles is not sufficiently smooth. This is a cause for concern when such articles are used as containers for high purity chemicals or linings for transport pipes, since contaminants tend to adhere to the surface and are difficult to remove even after attempts are made to clean the articles. In particular, the removal of contami...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B05D1/04B32B27/30C08F214/26C08J7/044C08L27/18C09D127/18
CPCC08J7/047C08J2327/18C08J2427/00C08L27/18Y10T428/24355C09D127/18C08L2205/02C08L2666/04Y10T428/31544C08J7/0427C08J7/044
Inventor NISHIO, TAKAO
Owner NISHIO TAKAO