40
Alice Davies PFC - STUDY Durable Water Repellency - TEST METHODS
Alice Davies
PFC - STUDY
Durable Water Repellency
- TEST METHODS
Alice Davies
De Montfort University
The Gateway
Leicester
LE1 9BH
United Kingdom
Thomas Schmid
Bundesverband der Deutschen
Sportartikel-Industrie (BSI) e.V.
Adenauerallee 134
D - 53113 Bonn
Germany
Author
Design
Disclaimer: Small updates and corrections to the source material were made in the process of creating this brochure.
Pictures: pixabay.com; © Halfpoint; Monkey Business; Giorgio Pulcini; Igor Mojzes; Maksym Protsenko; viktoriagavril; lazyllama; kuznetsov_konsta; ARochau; Maridav; Alexander Rochau - Fotolia.com
Dear Readers,
In October 2012 Greenpeace released a two part report called “Chemistry for any
Weather” which claimed that fabric finishes used on outdoor clothing contained
chemicals that are hazardous to the environment and human health. These substances
of concern are called perfluorinated chemicals (PFCs) and are traditionally found in
durable water repellent (DWR) fabric finishes because of their water, oil and soil
repellent properties.
The durable water repellents (DWR) currently available on the market can lead to
residues of perfluorinated chemicals (PFCs) in products themselves. Durable water
repellent based on C8 technology is the strongest chemical bond and is
considered a persistent, bio-accumulative and toxic (PBT) substance and has since been
detected around the world in the food chain, drinking water, animals and human blood.
In light of these resent scientific findings the Outdoor industry is working on new
environmental friendly durable water repellent solutions and a change of finishes for
their jackets. The Association of the German Sporting Goods Industry (BSI), the Outdoor
Industry Association (OIA) and the European Outdoor Group (EOG) are supporting the
Outdoor companies on this path and initiated the “Durable Water Repellent (DWR)
Project”. As part of this project, several scientific tests on a range of alternative
technologies to long-chain fluorochemical durable water repellents were conducted in
cooperation with the School of Fashion and Textiles De Montfort University, Leicester.
The results of these tests are presented to you in this magazine.
USE OF DURABLE WATER REPELLENTS IN THE OUTDOOR INDUSTRY
Durable Water Repellent (DWR) finishes are frequently used within the outdoor apparel
industry to provide fabrics with water and oil repellent properties. Fluorochemical-based
finishes have long been favoured for this purpose but have recently come under scrutiny for
their potentially hazardous properties and legislative and voluntary restrictions are now
being implemented across the industry. Secondary research revealed that alternative
technologies are increasing in availability and popularity but the performance levels, as well
as the environmental and health credentials, of these finishes are almost exclusively
communicated by the chemical suppliers themselves.
DWR finishes are used in many sectors of the textile industry to imbue fabrics with water and
occasionally oil repellent properties. The finish should prevent
drops of water from spreading on the fabric surface and wetting
the fabric; water drops should bead up on the surface, as shown
in Figure 1, and easily roll away. Liquid repellency is achieved
when the critical surface tension of a fabric surface is lower than
that of the liquid, so DWRs achieve their properties by reducing
the surface tension of the fabric to which they are applied .
DWRs are frequently used in the outdoor apparel industry
as they help to ensure protection against changing
weather conditions when engaging in outdoor activities.
They are often found on outer layer garments to provide
the first defence against the elements and may be used in
conjunction with other systems such as waterproof breath-
able fabrics. These finishes can also prolong the useful life
of a treated product, as the low energy surface created
Figure 1
4
prevents dry soil from adhering strongly to the fabric, so the product will not require
frequent washing and will remain looking newer for longer.
DWR finishes which contain long-chain perfluoroalkyl functionalities were introduced in
the 1950s and quickly became favoured by the textile industry: fluorochemical finishes
represented 90% of the DWR industry by 1990. They are still considered to provide the
best overall performance in terms of both water and oil repellency, making them
particularly favourable to the outdoor apparel industry.
The presence of fluorine, the most electronegative atom, allows PFC-based DWRs and
other fluorosurfactants to reduce the surface tension of the fabric to lower than that of
water and oil. The unique ability to repel oils as well as water has been a major
contributor to the popularity of PFC-based finishes. PFCs can create a surface tension
on a fabric as low as
10-20 mN mˉ¹ allowing
them to repel a variety
of oils with ease,
whereas PFC-free fin-
ishes, such as silicones
(24-30 mN mˉ¹) can
only reliably provide
water repellency.
These finishes are best imagined as “umbrellas on the surface of the fabric with the tips touching so that no water or oil can penetrate.” (P05 Project Team)
5
The telomerisation process used to synthesise PFCs often results in the fluorinated
polymers containing trace quantities of long-chain (often referred to as C8) perfluoroal-
kyl acids (PFAAs). PFAAs are not intentionally used in the manufacture of DWRs but are
present as impurities. PFAAs can be divided into two categories: perfluoroalkyl
sulfonates (PFSAs), most commonly associated with electrofluorination synthesis; and
perfluorocarboxylic acids (PFCAs) which result from telomerisation synthesis more
commonly used for repellents for clothing.
Long-chain PFAAs, specifically perfluorooctane sulfonate (PFOS) and perfluorooctanoic
acid (PFOA) have been the subject of heavy scrutiny because of their persistent and
bioaccumulative nature; they do not easily break down once they have entered the
environment or the bloodstream. PFOA is generally less bioaccumulative, and therefore
considered less hazardous, than PFOS.
PFSAs and PFCAs can reach the environment as impurities in other substances and from
the degradation of precursor substances as well as during their manufacture, use and
disposal. Liu and Avendaño suggest that PFOS and PFOA are among the most prominent
organic pollutants. Concentrations of these chemicals in water and soil are higher in
industrial areas, but they have also been detected in remote areas such as Lake Superior
in North America, the Hudson Bay in Canada and the Yangtze River in China. Similarly,
PFAAs have been found in blood samples of several fish, bird and mammal
species globally. That the presence of the chemicals is so widespread is proof of their
persistence and mobility in the environment.
Environmental and Health implications of PFC-based DWRs
6
The USEPA state that, although no adverse effects from PFAAs have been
identified in humans as of yet, given their effect on wildlife and laboratory tested
animals, coupled with their tendency to bioaccumulate, it is not unreasonable to deduce
that prolonged exposure in humans will eventually present negative impacts.
Several reports investigating the presence of PFOA in aquatic life, laboratory animals
and human blood samples support the USEPA statement, but data relating to the effect
of the substance on human health is still limited. A meta-analysis of available literature
concluded that the current data was insufficient to reliably suggest causality between
exposure to PFOA and adverse health effects in humans.
Greenpeace’s report “Chemistry for any weather” (2012) investigated the presence of
PFCs in outdoor apparel. A selection of products was tested from a range of leading
outdoor and sports brands. The report found no PFOS but found trace quantities of
PFOA in all samples and fluorotelomer alcohols (FTOH) (precursors) in most. Greenpeace
state that even these minor quantities should be considered hazardous and that the
outdoor apparel industry should “ban [PFCs] from its production processes and
immediately switch to safe functional alternatives”.
7
Impact on the outdoor industry
Many outdoor brands have responded to the issue, particularly since the Greenpeace
report was published, with most now including a statement regarding PFOA within their
environmental policies on the individual brand websites. However, it seems to be
unanimously acknowledged that there is currently no alternative repellent technology
which has been proven to be entirely safe as well as being able to meet the high
performance requirements expected by the industry. Generally speaking, brands have
responded to the issue by announcing that they will reduce and/or eliminate long-chain
(C8) PFCs and thus PFOA from their DWRs by a given deadline, with a number of brands
going one step further and committing to eventually eliminating all PFCs altogether. In a
survey conducted by De Montfort University and the EOG, many brands stated that they
are currently sourcing alternative technologies to replace PFC-based DWRs. While a few
brands are making this change independently, most have associated themselves with
voluntary environmental textile initiatives such as Bluesign, Oeko-tex and ZDHC. Table 2
gives a summary of the voluntary phase-outs that have been announced by outdoor
apparel brands.
Many brands stated that they are currently sourcing alternative technologies to replace PFC-based DWRs.
Brand name Voluntary association
PFC policies intentions Reference
Bergans Bluesign Using PFOA-free technologies (wax based
finishes)
Bergans (2014)
Descente Currently replacing C8 with C6
Descente (2014)
Didriksons Currently using PFC-free technologies in most products
Didriksons (2014)
8
Fjallraven Sustainable Apparel
Coalition
(SAC)
PFCs eliminated from all garments in 2012
PFCs to be eliminated from entire
product range by 2015
Fjallraven (2014)
W.L. Gore Bluesign Oeko-tex
Eliminated PFOA from all weatherproof functional fabrics in
2013
W.L. Gore (2014)
Haglofs Bluesign Provide a number of product lines which are free of PFCs
Haglofs (2014)
Jack Wolfskin ZDHC (signatory)
Elimination of PFOA by end of 2014
Elimination of all PFCs by end of
2020 (ZDHC)
Jack Wolfskin
(2012)
Klattermusen Bluesign Use of PFOA-free C6 in some shell garments
Otherwise PFC-free
Klattermusen (2014)
Maier Sports Fair Wear Foundation
(FWF)
Elimination of PFCs by end of 2020
Maier Sports (2014)
Mammut Bluesign PFOA free by 2015 Mammut (2014)
Marmot SAC C8 replaced with C6 in 65% of styles in 2013
Marmot (2012)
Ortovox ZDHC (supporter)
Eliminated C8 in 2011 Elimination of all PFCs by end of
2020 (ZDHC)
Ortovox (2014)
Patagonia Bluesign SAC
C6 used for the majority of DWR treated products
Patagonia (2013)
9
Table 2 Outdoor brands PFC policies and intentions
Schoeffel European
Outdoor
Conservation
Association
(EOCA)
PFOA-free C6 replacing all C8 in 2014
Schoeffel (2014)
Tatonka Aiming to eliminate PFCs Tatonka (2012)
The North Face
Bluesign Currently using Bluesign ‘best available technology’
The North Face (2014)
Vaude Bluesign Working to eliminate PFCs Currently using Bluesign ‘best
available technology’
Vaude (2014)
It can be expected that the alternative technologies being implemented are likely to require more frequent washing and re-proofing than PFC-
based repellents which are better able to resist soiling.
10
Potts suggests that consumers are largely unconcerned with sustainability issues relating
to textile products generally, in spite of much concern and effort within the industry.
Certainly, consumers seem to be largely unaware of the issues being raised over PFC-
based DWRs with as many as 77% of survey respondents answering that they were not
aware of any environmental or health implications of using these products (DWR-Study).
That is not to say that brands should not be concerned with consumer reactions, rather
they should take advantage of the opportunity to communicate the issue and realise the
benefits to brand credibility that could be gained by this, particularly if the individual
brand can be said to be actively working on solutions.
Consumer awareness
Legilsation
Greenpeace has not been the only source of pressure on the industry; a number of
government bodies, including the USEPA, Norwegian Pollution Control Authority, Danish
Environment Protection Agency and German Federal Environment Agency (UBA) have
all campaigned for PFOA as well as its pre-cursors to be restricted by law (use of PFOS is
already restricted to 1µg/m² (for textiles or other coated materials) within the European
Union as well as being regulated in Norway, Canada and Egypt (American Apparel and
Footwear Association (AAFA), 2013)). Due to a proposal put forward by German
authorities and supported by Norway, PFOA was recently added to the REACH
(Registration, Evaluation, Authorization and Restriction of Chemicals) candidate list of
Substances for Very High Concern (SVHC), meaning that the European Chemicals Agency
(ECHA) must be notified if:
The substance is present in those articles in quantities totalling over one
tonne per producer or per importer per year
The substance is present in those articles above a concentration of 0.1%
weight by weight (ECHA, 2013).
11
As PFOA is only present in unintentional trace quantities in DWR (<1ppm if detectable at all) this
particular regulation is unlikely to affect the outdoor industry, although it is worth considering
whether consumer awareness of such legislation could impact their purchasing decisions.
More notably, the Norwegian Environment Agency (2013) recently introduced a stringent
restriction on the manufacture, importation and exportation of PFOA: a limit of 1µg/m² for
PFOA in textiles will be effective from 1st June 2014. This is a much lower quantity than those
specified in the REACH legislation and with such a short timeline it is likely to pose significant
problems to many brands selling in to Norway: many of the samples tested by Greenpeace were
found to contain PFOA above this level. It is more likely than not that production of ranges for
Spring/Summer 2014 is already well under way, so even those brands that have made
commitments to reducing and/or eliminating PFOA may find that their deadline is not soon
enough to meet the new Norwegian restriction. Interestingly, despite Germany leading the
proposal for PFOA to be added to the SVHC list, it was Norway who first implemented more
stringent legislation.
IMPORTANT
PFOA was recently added to the REACH candidate list of Substances for Very High Concern
(SVHC).
IMPORTANT
The Norwegian Environment Agency recently introduced a stringent restriction on the
manufacture, importation and exportation of PFOA: a limit of 1µg/m² for PFOA in textiles
will be effective from 1st June 2014.
12
Voluntary environmental textile standards, Bluesign and Oeko-tex, have also specified limit
values for PFCs in their approved products: 0.05 mg/kg for Bluesign (2012) and 0.25 mg/kg for
Oeko-tex (2014). It is worth highlighting the discrepancy between the measurement units used
for these voluntary limits and those used in the legislative restrictions. Using mass based
measurements may be considered the best method for the industry to accurately monitor the
presence of PFOA in fabrics, but it will create confusion when assessing whether or not they are
within statutory limits.
Table 3 details all legislative and voluntary restrictions currently in place for PFOA and also
considers a number of potential restrictions expected to be introduced in the near future.
Organisation/ country
Limit for PFOA Reference
Legislative
REACH/ ECHA
SVHC Must notify ECHA if present in quantities
totaling over one tonne per producer or per
importer per year and above a concentration
of 0.1% weight by weight.
European Chemicals Agency
(2013)
Norway (Norwegian En-
vironment
Agency/ Norwe-
gian Product
Regulation)
1µg/m² - textiles and other coated materials
0.1 (product)
0.001% (liquid) (as of 1st June 2014).
American Apparel and Footwear Associa-
tion (2013); Norwegian
Environment Agency
(2013)
13
Voluntary
Bluesign 0.05 mg/kg textile. Bluesign (2012)
Oeko-tex 0.25 mg/kg. Oeko-tex (2014)
Potential
USEPA Considering use of the Toxic Substances Control Act (TSCA) section 6 to
manage long-chain PFAAs which would
authorise the USEPA to restrict or ban
manufacture and use of the chemicals.
Mowbray (2013b)
European Commission’s Sci-
entific Committee
on Health and
Environmental
Risks (SCHER)
Considering restriction of PFOA similar to current restrictions on PFOS – PFOS
is classified as very persistent, very
bioaccumulative and toxic and is restricted to
1µg/m² for textiles in the European Union.
American Apparel and Footwear Associa-
tion (2013); Mowbray
(2013b)
Table 3 Legislative, voluntary and potential restrictions for PFOA
14
Impacts and developments: chemical suppliers
As outdoor brands have been phasing out long-chain PFC technologies, demand has
been high for effective alternatives. Mowbray notes that while there are currently no
PFC-free technologies that can perform as well as C8 finishes, there are a number of
alternatives available that can provide acceptable water repellency and light stain
resistance. Most of the leading chemical suppliers to the outdoor industry now include
short-chain PFC as well as PFC-free repellents in their ranges and these have been
readily advertised as being safer and effective alternatives. It stands to reason that the
performance of such alternatives is improving as increased demand necessitates that
more time and funding be put into their development. However, all available
information regarding the performance of these new alternative technologies is being
communicated by the chemical suppliers themselves and as such is inherently biased.
Added to which, non-PFCs are not able to provide any oil repellency, so they are
already acknowledged to be inferior in performance to the previously favoured PFCs.
This supports the need for an evaluation of the test methods and performance
requirements specified for DWRs so that brands can more effectively establish the true
implications of making changes to their current technologies.
While it is encouraging that chemical suppliers are revising their formulas in order to
create safer products, little data is provided about the true environmental and health
impacts of the alternative finishes. The P05 Project Team note that some alternatives
are associated with other potentially hazardous chemicals and that limited available
data makes it difficult to make reliable claims of safety and this confuses the situation
for brands and consumers.
15
The USEPA established their PFOA Stewardship Program in 2006, in partnership with
eight leading chemical suppliers including DuPont, Clariant and 3M.
The programme is a voluntary effort by the suppliers to reduce process and product
content and emissions of PFOA, with an elimination date set as the end of 2015. This is
in line with some of the brand elimination commitments, and with these prominent
chemical companies engaged in creating replacements, it is likely that brands will face
difficulty in accessing long-chain repellents at all after this date. This supports the need
to assess the performance levels of alternative technologies so that brands and
consumers are fully aware of any drop in performance that may result from their
implementation.
While there are currently no PFC-free technologies that can perform as well as C8 finishes, there are a number of alternatives available that
can provide acceptable water repellency and light stain resistance.
16
The alternative technologies identified were found to fit within one of three broad
categories: short-chain fluorochemical, fluorine free or novel methods of application.
As discussed before, many outdoor brands are choosing to reduce PFOA in their
products by turning to short-chain PFC repellents and those who have committed to
elimination of all PFCs can be assumed to be making use of fluorine free technologies.
Novel application methods are perhaps less favourable as they are often still based on
long-chain PFCs, although much lower levels of fluorochemical are required to achieve
good repellency.
Short-chain fluorochemical-based
Short-chain PFACs are those containing either six or four fluorinated carbons (termed
C6 or C4 respectively) and are chemically similar to their long-chain homologues (such
as PFOA, C8). As chain length has a considerable impact on tendency to persist and
bioaccumulate, short-chain PFCs are expected to be less stable in the environment and
less bioaccumulative. Data for non-human primates has shown these shorter-chain
PFACs to have shorter half-lives and therefore to be less toxic than long-chain PFACs.
As they are fluorochemical based, short-chain repellents can provide some oil and stain
repellency, although there is currently no technology which can achieve the same
performance levels as C8 repellents; as can be seen in Table 4, chain length has a
significant impact on the oil and water repellency performance of PFC-based finishes.
Alternatives to long-chain fluorochemical-based Durable Water Repellents
17
Perfluorinated groups Measurement of oil repellency (AATCC 118)
Spray test (ISO 4920)
- CF₃ 0 1
- CF2 - CF3 3-4 2
- (CF2)2 - CF3 6-7 2
- (CF2)4 - CF3 7-8 2
- (CF2)6 - CF3 (Short- chain - C6)
7-8 2
- (CF2)8 - CF3 (Long- chain - C8 e.g. PFOA)
8 3
Reduced stability also means that short-chain repellents are less durable when applied
to a fabric, and it is suspected that application of up to 50% more chemical may be
necessary to limit any drop in performance. However, higher amounts of the finish may
negatively affect the fabric’s physical properties such as handle, drape and breathability.
Short- and long-chain fluorochemical finishes are compatible with dyes and auxiliary
agents and can be applied as a water-based dispersion by a padding method.
Alternatively, methods of minimum application including nip padding, lick-roll or
vacuum extrusion may be utilised .
Table 4 Effect of fluorochemical chain length on oil and water repellency
IMPORTANT
Short-chain repellents, as they are fluorochemical based, can provide some oil and stain repellency.
18
Fluorine-free
There are a range of fluorine-free technologies that can be used to imbue fabric with
water repellent properties, including but not limited to: wax/paraffin, silicone and
stearic-acid melamine. Fluorine-free finishes do represent a drop in performance but
can usually be considered acceptable in all but the harshest of conditions. The main
variant in performance between fluorochemical and fluorine-free repellents is that the
fluorine-free finishes do not provide any oil repellency. It is assumed that a level of oil
repellency is essential to keep DWR treated fabrics cleaner for longer, therefore
prolonging the water repellency between washes.
However, Figure 5 shows that oil, dirt and soil
repellency are not considered essential for sports/
outdoor fabrics in terms of fluorochemical require-
ments and that water repellency and fabric handle
are significantly more important features. Perhaps
it is the case that oil repellency is simply a bonus of
PFC-based finishes, but one that the outdoor
industry would not suffer without .
This is supported by the fact that respondents to brand and
consumer expectation surveys were found to be in
agreement that dirt/soil repellency was the least important
property in a DWR treated garment (DWR-Study).
However, reduced oil repellency may mean that the fabric
gets dirty more quickly which can effect water repellency in
the first instance and may also necessitate more frequent washing which again could
result in a reduction in repellency performance overall.
Figure 5
19
It is also worth noting that fluorine free finishes can reduce the adhesion of additional coatings
or laminates that may also be required on the fabric and so a change in processing conditions
may be necessary to alleviate such difficulties .
Wax
Paraffin/ wax based finishes were some of the earliest examples of water repellent finishes;
natural oils and resins were being used to create waxed fabrics as early as the 18th century. The
types of wax repellents still in wide use today were popularised throughout the 20th century.
They are typically formulated as emulsions incorporating aluminium or zirconium salts of fatty
acids which attach to the fibre, allowing the repellent groups within the chemical structure to
effectively orientate and achieve good levels of water repellency.
These finishes do not provide any oil repellency and they tend not to be durable to laundering
processes. This is likely to increase the frequency of re-proofing treatments required compared
to PFC finishes.
Paraffin/wax finishes are most commonly applied in aqueous form by a padding method
followed by hot calendaring to melt and evenly distribute the wax across the fabric surface.
IMPORTANT
Fluorine-free finishes do represent a drop in performance but can usually be considered
acceptable in all but the harshest of conditions. The main variant in performance between
fluorochemical and fluorine-free repellents is that the fluorine-free finishes do not provide
any oil repellency.
Oil, dirt and soil repellency are however not considered essential for sports/outdoor fabrics.
20
Silicone
Silicones based on polysiloxanes were first used as water repellents for textiles in the
1950s and have been a popular technology since. Polydimethylsiloxanes are the most
commonly used silicone repellents as their structure allows them to form hydrogen
bonds with fibres whilst displaying a hydrophobic outer surface. Silicone repellents
usually consist of a silanol, a silane and a catalyst such as tin octoate to ensure
durability; the catalyst enables good orientation of the silicone film on the fibre surface
with the outward facing methyl groups (of the silicone polymer) providing water
repellency, the silanol and silane then react during the drying process to create a three-
dimensional, cross-linked sheath around the fibre.
Although silicones are considered to be less harmful than PFCs, they are not without
concern as waste water from the application processes of silicone finishes can be toxic
to fish. Silicone finishes can provide good water repellency at relatively low
concentrations, but they cannot provide any oil repellency and tend not to be very
durable to laundering processes.
Most commonly, silicone finishes are applied as an aqueous polysiloxane emulsion by
padding, followed by drying and curing. Full repellency is observed after ‘ageing’ for 24
hours. Alternatively, some silicone finishes can also be applied by an exhaustion
process to reduce waste consumption.
Figure 6 Example of a polydimethylsiloxane silicone repellent: A,
hydrophobic surface; B, hydrogen bonds to polar surface; C, fibre surface
21
Stearic acid-melamine
Stearic acid-melamine repellents are formed by reacting stearic acid and formaldehyde
with melamine; the stearic acid groups demonstrate water repellency while the
N-methylol groups are able to either react with the fibres or with each other in order to
crosslink and create repellency.
The potential release of formaldehyde is a significant disadvantage of these repellents
and is a recurrent issue across the textile industry. Formaldehyde is toxic to human
health (European Inventory of Existing Commercial chemical Substances, 2014c) and is
classified as Group 1 - Carcinogenic to humans by the International Agency for Research
on Cancer (IARC).
Stearic acid-melamine repellents demonstrate good durability to laundering but can
affect some physical properties of the fabric, with decreased tear strength and abrasion
resistance being common disadvantages.
These repellents can be applied by a padding process before being stenter dried and
cured in a well-ventilated unit. It is often possible to combine stearic acid-melamine
repellents with other easy-care finishes in the pad bath providing they are chemically
compatible. Alternatively, some finishes of this type can be exhaust applied.
22
Treatments applied by novel methods may still contain PFCs (allowing them to retain
the high performance attributes such as excellent oil as well as water repellency), but
the application and synthesis methods usually present lower risk to the environment
and to human health than traditional treatments due to reduced amounts of solvents
required and reduced waste.
Nanotechnologies
The synthesis and application of nanotechnology finishes does not require the large
amounts of water and solvents usually associated with textile finishing which is
beneficial in terms of environmental impact. However, although potential health
implications have not been widely studied, preliminary evidence suggests that the
smaller particles utilised in nanotechnologies are potentially more of a risk because of
increased mobility due to their size; it is thought that they may be more readily
transported in blood and other cells.
Monomers containing long perfluoroalkyl chains linked to a polymerisable carbon-
carbon double bond can be polymerised by plasma nanotechnology methods, reducing
the need for solvents. There are two main application methods for plasma treatments:
vacuum application which is a small scale method usually performed on individual
items, and atmospheric application which can be used in larger scale, continuous
processing such as for rolls of fabric, making it more relevant to the textile industry.
Nanotechnologies are able to provide excellent water repellency (and oil repellency
when based on fluorochemicals) along with various other surface functionalities such
as UV protection, flame retardation, anti-static, anti-bacteria and wrinkle resistance.
Novel application methods
23
This could potentially be a viable solution for the outdoor industry to allow them to
retain the benefits of PFCs, assuming that the lower amounts of fluorochemicals
required in nanotechnology applications fall within legislative restrictions.
Dendrimer
Dendrimer repellents are characterised by highly branched monomers which create
monodisperse, tree-like structures on the fabric surface. The formation of these
monodisperse polymers requires the dendrimer to be built up one layer at a time in a
highly controlled process.
Dendrimer technology can provide good water repellency and can also be combined
with fluorocarbon polymers, forcing them into a more ordered and effective structure.
This method provides oil repellency as well as equal or better water repellency with
lower amounts of fluorochemicals than non-dendrimer finishes.
As previously discussed, many of the chemical suppliers to the outdoor industry are
reducing their use of PFCs and are actively working to formulate alternatives. As such, a
number of short-chain, fluorine-free and novel repellents are commercially available to
outdoor brands. A range of these repellents was identified from a number of sources
including brand websites, journals and personal contact through the EOG and BSI.
Table 7 details the suppliers and repellents identified by the search. All suppliers listed
were then contacted to request treated fabric samples for testing.
Commercially available Durable Water Repellents
24
Supplier Repellent
name
Repellent type Reference
Alexium Cleanshell C6 (PFOA free) Alexium (2013)
Asahi Kasei Asahi Guard
E-series
C6 (PFOA free) Hounslea
(2013e)
Clariant Nuva N1811 C6 fluorocarbon (PFOA free) Coates
(2013)
Clariant Arkophob FFR
Fluorine free repellent (Type not stated)
Hounslea (2013d)
DuPont Capstone Short-chain fluoro (cannot break down to PFOA)
DuPont (2013)
Europlasma Nanofics 110 Plasma based nano-coating Hounslea
(2013f)
HeiQ BarrierECO Hydrophobic, hyper-branched
polymers
HeiQ (2013)
Huntsman PHOBOL C6 fluorocarbon Lane (2013)
Huntsman PHOBOTEX Fluorine free hydrocarbon Lane (2013)
Nanotex Aquapel Molecularly attached
hydrophobic 'whiskers' attached to individual fibres. Uses a hydrocar-bon polymer.
Nanotex
(2013)
P2i ion-mask Plasma based nano-coating Mowbray
(2012)
Purtex Purtex WR Polyurethane emulsion. Greene (2013)
Rudolf Ruco Guard C6 fluorocarbon (PFOA free) Rudolf Group (2013a)
25
Rudolf Bionic-finish
ECO
Dendrimer Rudolf Group (2013b)
Schmits
Chemical Solutions
Bemiguard C6 fluorocarbon Butler
(2013)
Schoeller ecorepel Based on paraffin chains. Butler
(2012)
Tanatex HyrdECO range
Based on '3D' molecules Mowbray (2013e)
TexChem Texfin C6D C6 fluorocarbon (PFOA free) Robinson (2013)
TexChem Texfin HTF Modified wax dispersion Robinson (2013)
TexChem Texfin SWR- A/SWR-B
Silicone based PFC free Robinson
(2013)
Table 7 Commercially available Durable Water Repellents
The majority of suppliers assert that their finishes can offer adequate water repellency for
outdoor use, with some claiming to match the performance of PFCs for newly treated fabrics.
Few claims are made regarding the durability of alternative repellents and all available
information relates to laundering only. Methods for observing repellency performance in new
fabrics were rarely referred to and no other durability methods seemed to have been explored.
The majority of suppliers assert that their finishes can offer adequate water repellency for outdoor use, with some claiming to
match the performance of PFCs for newly treated fabrics.
26
The majority of suppliers contacted were willing to offer samples and Table 8 shows
the full selection of repellents that were received (supplier/brand names have been
removed to conserve anonymity). The selected observation, durability and restoration
methods (spray rating with percentage weight increase, immersion and tumble drying
respectively) were performed on the sourced repellents. As these fabrics varied in fibre
content, fabric construction and weight there was some variation in performance even
between repellents of the same type. It would be impossible to include every possible
combination of repellents, fabrics and processing conditions but a sufficient indication
of the current performance of commercially available repellents was gathered from
this selection. Another variable to consider is the processing conditions used to apply
the repellents to the fabric as this can have a considerable impact on the performance.
Similarly, the conditions used in a small lab environment when creating samples may
be completely different again to those used in bulk production. The majority of
suppliers contacted considered processing information to be confidential.
Repellents acquired for testing
Repellent type Fabric content
Plasma (C8) 100% Cotton (CO)
Plasma (C8) 100% Nylon/Polyamide (PA)
C8 100% PA
C8 100% PA
C8 100% Polyester (PES)
C8 100% PES
C8 100% PES
27
C6 100% CO
C6 100% PA
C6 100% PA
C6 100% PA
C6 100% PES
C6 100% PES
C6 100% PES
C6 100% PES
Dendrimer 100% PA
Dendrimer 100% PA
Wax 100% PA
Wax 100% PA
Wax 100% PES
Wax 100% PES
Wax 100% PES
Wax 94% PES, 6% EL
Silicone 100% CO
Silicone 100% CO
Silicone 100% PA
Silicone 100% PES
Polyurethane 100% PA
Polyurethane 100% PA
Table 8 Commercially available repellents sourced for testing
28
Observational test methods on new fabrics revealed that the PFC-based finishes
(plasma, C8 and C6) consistently performed better than those which were PFC-free.
Interestingly short-chain PFCs did not perform significantly worse than long-chain
finishes; all C6 and C8 repellents tested achieved comparable spray ratings, although
some of the C6 samples demonstrated slightly higher levels of water uptake. The plasma
based finishes outperformed all others which was to be expected as this application
method allows the entire fibre to be covered with repellent where as other traditional
application methods can only cover the surface of a fabric.
Both dendrimer finishes tested achieved spray ratings comparable to PFCs but exhibited
much higher weight increase due to water uptake. This can be seen in Figure 9 which
shows the visual difference in the amount of water sticking to the surface of a PFC
repellent compared to a dendrimer sample. Although neither of the fabrics pictured
exhibited any sign of wetting, the amount of water sticking seen on the dendrimer
treated sample may be considered undesirable for some brands and consumers. That
said there was a larger discrepancy between samples seen for this repellent type than
for any of the others and further testing would be required before assuming that these
results were indicative of all dendrimer repellents.
Initial observations
C8 Dendrimer
Figure 9 Spray rating of
PFC-based repellent
compared to dendrimer
repellent
29
All other PFC-free repellent types tested – wax, silicone and polyurethane – performed
similarly in terms of both spray rating and weight increase with no significant
differences between the three. All exhibited lower spray ratings than long-chain PFC
repellents (although most were still within the pass criteria specified by the industry:
spray rating 80 (ISO 3)) as well as noticeably higher water uptake.
Results of initial observational methods on all fabrics are represented in Figure 10.
Average spray rating is plotted against average percentage weight increase and the
standard deviation between samples within each type is represented by the size of each
‘bubble’. As such, data points falling in the top left on the plot area represent the best
possible repellency performance and smaller bubbles represent best possible
consistency between tested samples.
PFC-based finishes (plasma, C8 and C6) consistently performed better than those which were PFC-free. Interestingly short-chain PFCs
did not perform significantly worse than long-chain finishes.
Figure 10 Comparison of repellency performance for all new fabrics
30
Subjecting all sourced fabrics to the immersion test revealed that the performance of all
repellent types was negatively affected by this durability test, with lower spray ratings
and higher weight increases observed in all cases.
Long-chain PFCs were the most resistant to immersion, with slight reductions in spray
rating observed and very little difference to weight increase. The short-chain, C6 repel-
lents changed more significantly, resulting in a slight drop in average spray rating and
percentage weight increase entirely outside of the range seen prior to immersion. While
the repellency performance of C6 samples reduced noticeably after immersion, the wax
and silicone repellents tested were similarly resistant to long-chain PFCs, with very little
change in performance discerned after this durability test. Dendrimer and polyurethane
repellents demonstrated weight increases outside of the range seen before immersion,
suggesting that these repellent types were among the least resistance to immersion.
That said, unlike C6 and polyurethane, the dendrimer repellents did not show any
reduction in spray rating.
These changes in performance after immersion are demonstrated in Figure 11,
in comparison to results recorded from new .
Resistance to immersion
31
Figure 11 Comparison of repellent performance for all fabrics after immersion
After tumble drying for 30 minutes, repellency performance improved for all repellent
types. Interestingly, further tumble drying up to 60 minutes did not result in further
improvement to repellency in the case of most fabrics as is demonstrated in Figure 12. It
can also be seen from this that tumble drying did not necessarily fully restore
performance, as average weight increases were still slightly higher than those seen from
new.
Restoration after tumble drying
32
That said, once standard deviation between the samples is accounted for it can be seen
that performance for all repellent types returned to within the range initially recorded
before immersion after tumble drying for 30 minutes, as shown in Figure 13.
Interestingly, those repellents which were most effected by immersion, were similarly
most affected by tumble drying, although this could be put down to the fact that
repellent types which were quite resistant to immersion, did not actually require a
great deal of restoration. In any event, tumble drying was found to be an effective way
of recovering repellency performance after prolonged exposure to water for all
repellent types tested.
Figure 12 Comparison of weight increase for all fabrics after tumble drying
33
Figure 13 Comparison of repellent performance for all fabrics after 30 minutes tumble drying
IMPORTANT
After tumble drying for 30 minutes, repellency performance improved for all repellent types.
34
PFC-based finishes have become favourable for use as DWRs in the outdoor
industry due to their ability to effectively lower the surface tension of a fabric enough to
repel oils as well as water, a feature which alternative finishes cannot offer. Long-chain
PFC based repellents have been identified as the best possible technology in terms of
both water and oil repellency but the unintentional by-products, long-chain PFAAs,
particularly PFOA, associated with these chemicals have come under increasing scrutiny
due to their tendency to persist and bioaccumulate in the environment. That said, there
is a lack of clarity within the data currently available as to the exact implications of this
in terms of both environmental and health considerations and as to the true
contribution from DWRs to the total presence of long-chain PFAAs in the population.
The outdoor industry certainly stands to benefit from continued involvement in this
research.
As a prominent consumer of PFCs, the outdoor industry has been heavily implicated in
the debate regarding their questionable safety, particularly since the release of the
Greenpeace reports which brought the topic to a wider public audience. Also, this
debate has likely influenced a moral reaction within the industry as by its very definition
it is largely supportive of environmental preservation and, as was suggested in the
Greenpeace reports, consumers may find it hypocritical if outdoor brands did not take
seriously any measures to reduce their own environmental impact. As well as moral
pressures, the industry also faces a number of legislative restrictions to the production
and use of PFOA. Voluntary limits have also been suggested by both Bluesign and Oeko-
tex, although a discrepancy between the measurement units used by these voluntary
standards and the legislative restrictions is likely to create confusion; addressing this by
standardising the measurement units used for textile items would be beneficial to all
involved. All measures considered, it is not unreasonable to predict the eventual phase-
Conclusions: Durable Water Repellents in the outdoor industry
35
out of all long-chain PFC-based repellents on the part of both brands and chemical
suppliers within the outdoor industry. The performance credentials of alternative
technologies are largely communicated by chemical suppliers themselves, throwing
into question the objectivity and validity of the claims. In spite of this, the majority of
outdoor brands have committed to reduce and/or eliminate long-chain PFC-based
DWRs by a given deadline, with many stating that they are currently sourcing replace-
ment technologies. Those brands which have chosen to move to short-chain PFC-
based repellents may have to take particular notice of any changes in legislation as the
current limits might eventually be extended to also include shorter chain length
technologies. At present, consumers are largely unaware of the issue, with 77% of
respondents to the end user expectations survey answering that they were not aware
of any environmental implications of using PFC-based DWRs. In spite of this, any
changes in the performance of DWR treated garments will ultimately be felt by the
wearer, as will any increase in cost; it is unlikely that consumers would be willing to
accept a higher price-tag for poorer performance especially if the environmental and
health benefits are not validated or well communicated. While the matter may not
currently be considered a consumer facing issue, better communication will eventually
be required for brands to justify changes in technology.
Application of heat by tumble drying was found to be an effective method for
improving repellency performance after prolonged exposure to water. The best
results were observed after 30 minutes, with little or no further improvement
recorded after longer intervals (up to 60 minutes). Those repellents which were most
affected by immersion were also most responsive to tumble drying, suggesting that
while those repellent types may lose performance more quickly this could be
combated, at least in part, by more regular application of heat.
Approximately 70% of consumers stated that they do not tumble dry their DWR treat-
36
Performance of commercially available alternatives to long-chain fluorochemical Durable Water Repellents
ed garments, suggesting either that they simply do not have this facility available to
them or that they are unaware of the benefits it can represent. This is in contrast to 65%
of brands who recommend some form of tumble drying, suggesting that there is a lack
of communication on this matter. Although a marked improvement was observed,
application of heat in this way still did not fully restore the repellency performance for
most repellent types. This supports brands recommendations for re-proofing of DWR
treated products. Much further investigation could be carried out into the use and
effectiveness of commercially available re-proofing products.
A range of alternative technologies were identified and found to be readily available
from chemical suppliers to the outdoor industry. This commercial availability has likely
been influenced by increased demand from outdoor brands on top of the legislative and
voluntary restrictions previously discussed. Additionally, eight of the leading chemical
suppliers have engaged with the USEPA in a voluntary commitment to reduce and
eventually eliminate process and product content and emissions of PFOA.
Seven main repellent types were identified as being available to the outdoor industry:
plasma (long-chain PFC), C8 (long-chain PFC), C6 (short-chain PFC), dendrimer, wax,
silicone and polyurethane. Several suppliers stated that their finishes were free of
fluorochemicals but were not willing to disclose the specifics of the type of technology
used. A selection of fabrics representing the seven repellent types were sourced and
tested in line with the testing procedures already described.
37
Based on these methods long-chain PFCs demonstrated higher performance than all
alternatives in all observational and durability tests performed. Plasma treated fabrics
tested were C8-based and consistently demonstrated the best performance. This was
expected due to the plasma application method allowing for better fibre coverage
but, it should be noted that the samples sourced were treated by a vacuum method
and atmospheric plasma treatments (more likely to be used for large scale textiles
processing) may perform differently. It is also unclear whether the amounts of
fluorochemical used in plasma treatments fall within the legislative restrictions being
implemented; brands would need to investigate this further before deciding on this
technology as a commercially viable replacement for standard C8 repellents.
C6 repellents were found to be the next best in terms of repellency performance;
overall repellency performance was largely comparable to C8 from new but C6 was
less resistant to prolonged exposure to water. Similarly dendrimer based repellents
exhibited little difference in terms of spray rating however, the weight increase
measured was significantly higher than, not only long-chain PFCs but, all other
repellent types. That said, these weight increase results were not consistent between
samples of this repellent type and this could be due to any number of reasons
including differences in processing conditions used or the specific fabric
constructions.
Other alternative repellent types all performed similarly; wax, silicone and
polyurethane treated samples all achieved lower spray ratings than traditional long-
chain PFC repellents (although most were still within the pass criteria specified by the
industry: spray rating 80 (ISO 3)) as well demonstrating noticeably higher weight
increases.
38
Polyurethane samples tested were the least resistant to prolonged exposure to water
and all fell below the pass boundary (spray rating 80 (ISO 3)) required by the majority
of outdoor brands.
As previously discussed, all repellent types exhibited performance improvement after
tumble drying for 30 minutes with all returning to within a similar range as the
performance observed on each sample from new.
In conclusion, based on the methods used and the repellents tested within this
project, no alternative technologies were found to rival the performance level offered
by long-chain PFC-based DWRs although all exhibited acceptable performance levels
before durability testing. As implementing any alternative technologies would
represent a drop in performance, outdoor brands will have to consider how they are
going to justify this change to consumers, particularly as legislative measures and
greater awareness of the issue are contributing to a reduction in availability of the
traditionally favoured long-chain PFCs.
39
European Outdoor Group (EGO)
Gartenstrasse 2
6304 Zug
Switzerland
www.europeanoutdoorgroup.com
Bundesverband der Deutschen Sportartikel-Industrie (BSI) e.V.
Adenauerallee 134
D - 53113 Bonn
Germany
www.bsi-sport.de
Outdoor Industry Association
4909 Pearl East Circle, Suite 300
Boulder, CO 80301
United States of America
www.outdoorindustry.org
