Abstract Glass fabric coated with polytetrafluoroethylene is made crackfree by applying a top coat of a melt fabricable tetrafluoroethylene copolymer which is heat bondable to said polytetrafluoroethylene, followed by heating the resultant fabric sufficiently to sinter the polytetrafluoroethylene; this heating also melts the copolymer top coat. A polytetrafluoroethylene over coat can be applied to the copolymer top coat if desired. The dip coating process for applying the polytetrafluoroethylene to the glass fabric is improved by flooding a surface of the fabric with an aqueous dispersion of polytetrafluoroethylene prior to dip coating so that wicking of the dispersion through the thickness of the fabric occurs prior to dip coating.
The glass fabric of claim 1 having an over coat of sintered polytetrafluoroethylene on said copolymer top coat.
Claim 2
Dependent Claim
11 words
The glass fabric of claim 1 weighing at least 8 oz./yd.2.
Claim 3
Dependent Claim
20 words
The glass fabric of claim 1 wherein the apertures between yarn of the fabric are at least 6 mils wide.
Claim 4
Dependent Claim
11 words
The glass fabric of claim 4 weighing at least 8 oz./yd.2.
Claim 5
Dependent Claim
69 words
A process for preparing a crack-free polytetrafluoroethylene coated glass fabric, comprising applying a base coat of unsintered polytetrafluoroethylene to said fabric, applying to said base coat a top coat of melt fabricable tetrafluoroethylene copolymer which is heat bondable to said polytetrafluoroethylene, heating the resultant fabric sufficiently to sinter said polytetrafluoroethylene, followed by cooling the resultant fabric, the heating and cooling thereby fusing the top coat to the base coat.
Claim 6
Dependent Claim
52 words
The process of claim 6 wherein the polytetrafluoroethylene is applied in the form of a dispersion having from 55 to 65 percent by weight polytetrafluoroethylene dispersed therein, said polytetrafluoroethylene having an average particle diameter of at least 0.3 micron, and at least 1 percent surfactant based on the weight of said polytetrafluoroethylene.