Bob Ruckle and Tom Seung-Tong Cheung, Siltech Corp.
Introduction
Fluoroalkyl modified silicones have been available for many
years. Offering additional properties over simple polydimeth-ylsiloxanes, these have found utility in coatings for slip, COF,
mar resistance, stain resistance, lubricity, hydrophobicity and
oleophobicity.
Regulatory and safety concerns over perfluorooctyl’s persistence in the environment have put pressure in recent years
on these systems1. In general, chemical manufacturers have responded with shorter chains to obtain the unique properties of
fluoroalkyls while eliminating this environmental concern.
Fluoroalkyl silicones used in this study are based on a three-carbon chain and so are not affected by current regulatory actions.
In this paper, we have modified some coatings systems with
our fluoroalkyl silicones and examined the effect on the cured
film properties.
Experimental and Methodology
The overall design is to evaluate multiple fluoroalkyl silicones
in five coating systems; a two part solventborne heat cured ure-
thane system, a UV cured urethane acrylate system, a UV cured
epoxy acrylate, a cationic epoxy UV formula and a commercial
paint to examine the effects of these products in broad strokes.
To synthesize the fluoroalkyl silicone materials used herein, several silicone backbones were modified with fluoroalkyl
alone; fluoroalkyl and polyether; or fluoroalkyl and alkyl using
well known hydrosilylation procedures.
The fluoroalkyl silicones designated as FA 1, FA 2, FA 3, FSE
1 and FSE 2 are primary hydroxyl functional and can therefore
react with the PU system. The material designated as FA 3ACR
is an acrylate ester analogue of Sample FA 3 and can therefore
react into the UV cured acrylate system.
The FS 1 and FS 2 additives offer a high (44%) and a low
(14%) CF2 content material for comparison. Likewise the FA
1, FA 2, FA 3 series offers CF2 contents at low, medium and
high for comparison. FA 3 ACR will show the effect of reacting
when compared to FA 3.
The FPE 1 and FPE 2 have very low CF2 contents and going
into the study we expect them to offer little in terms of slip or
mar and stain resistance. Likewise the FA 4 can be compared
to FA 3 and FS 2 to see the impact of including CH2 content.
A series of non-PFOS fluoroalkyl silicones will be examined in UV cured coatings films
for their impact on coatings properties such as appearance, COF reduction, and mar,
stain and fingerprint release. Both reactive and non-reactive fluoroalkyl silicones
will be examined. Earlier results of reactive silicones in films have shown interesting
results on stain release and the hope is that the fluoroalkyl group will enhance these
properties in particular.
Incorporation of
Fluoro-Silicones in
Coatings Films and the
Resulting Properties
