3 Chemical Treatment Methods
3.1 Introduction
Generally there are different ways that low energy surfaces can be applied to textiles. Perhaps the oldest
method is mechanical incorporation of the water-repellent products into or onto the fibre and fabric surface,
in the fibre pores and in the spacing between the fibres and the yarns. Examples of these are paraffin
emulsions. Another approach is the chemical reaction of the repellent material with the fibre surface.
Examples of these are fatty acid resins and silanes.
Another method is the formation of a repellent film on the fibre surface. Examples of these are silicone and
fluorocarbon products. The use of special fabric constructions as a method achieving low surface energy
has also been mentioned in the literature (Funktionelle Sporttextilien, 1989; Holme, 2003).
Perfluorinated chemicals have been produced and used since the 1950s since they are thermally stable,
and repellent to water, dirt and grease. Perfluorinated substances are a group of organic compounds
characterised by a carbon chain in which all hydrogen atoms have been replaced with fluorine atoms.
Historically, the major share of the repellent market was held by C8 perfluorinated substances. However, it
is now known that PFOS has very serious effects on health and the environment and consequently PFOS
and related substances are being phased out. To replace PFOS, several manufacturers have moved
towards other fluorinated compounds that have the same desirable technical properties. Unfortunately,
several of the replacement compounds have been shown to have similar negative effects on health and
environment.
Since their introduction in 1943, silicones have been applied in an exceptional variety of industries. In many
cases, silicones have gained acceptance and are used commercially either as coatings or as additives
because of their unique surface properties. Silicon-based technology emulsions could provide durable water
repellency and softness to textile substrates, particularly cellulosic and blends including cotton and
cotton/polyester blends.
Depending on the nature of silicone molecule, the water repellency imparted could be designed to be
durable to a high level essentially similar to that imparted by standard fluorocarbon water repellent finishing
systems in the market. Leading brand apparel companies are looking for innovative water repellency
technologies that can provide eco-friendly solutions for their garments without sacrificing comfort and
silicones would perfectly lend themselves to such applications.
Nanotechnology is an umbrella term covering a wide range of technologies concerned with structures and
processes on the nanometre scale. Because of its potential to change fundamentally whole fields of
technology, nanotechnology is regarded as a key technology, which could potentially influence technological
development with economic, social and ecological implications.
Nanotechnology deals with the science and technology at dimensions of roughly 1 to 100 nanometres and
has been used to engineer desired textile properties such as fabric softness, durability, breathability and in
developing advanced performance characteristics, namely, water, oil and soil repellency, fire retardancy,
antimicrobial resistance, etc in fibres, yarns and fabrics (EU Report, 2004).
3.2 Fluoropolymers
a. Overview
Historically, durable water repellents (DWR) containing long perfluoroalkyl chains have been the chemistry
of choice for textile applications. Perfluorinated chemicals are used to incorporate raw materials containing a
perfluoroalkyl chain into acrylic or urethane polymer that are used as DWR finishes. When applied to
fabrics, these finishes form a structure on the outer surface of fibre to provide maximum repellency. The
D1.2
Copyright © TEXSHIELD Project Consortium 2013
4
unique water and oil repellency properties of DWR finishes are derived from the perfluoroalkyl chain that is
attached to the acrylic or urethane polymer backbone.
DWR finishes containing long-chain perfluoroalkyl functionality are modified to have a wide range of
properties to fit the different demands of the users and the intended purpose. They allow reduction in
volume of the finishes that can be applied and consequently reducing associated costs and life-cycle
impacts for a treated garment (Davis, 2011; Texchem, 2012). They also have excellent chemical and
thermal stability which provides treated fabrics with good durability (eg during laundering and dry-cleaning
(Ceria, 2010). Most repellents based on this chemistry are applied by padding process and then dried and
cured (Schindler, 2004), see Figures 3 and 4.
Figure 3 Schematic diagram of padding equipment.
Figure 4 Image of stenter for drying padded fabric.
Long-chain perfluoroalkyl acids (PFAAs) as well as polymer and surfactants containing long-chain
perfluoroalkyl functionality (termed by some as “C8”) that may degrade to form long-chain PFAAs have been
widely used in numerous industrial and commercial applications since the 1950’s (Kissa, 2001; Buck et al,
2011). Long-chain PFAAs including PFOA and PFOS have been detected globally in the environment,
wildlife and humans.
Concerns about the potential environmental and human health impacts of these long-chain PFAAs have led
to actions by regulatory authorities and industry. Long-chain PFAAs have been defined as (i)
perfluorocarboxylic acid (PFCA) and perfluoroalkyl sulfonates (PFSA) with a minimum of 8 and 6 carbon
chain lengths, respectively and (ii) substances, such as fluorinated polymers that may break down to form
long-chain PFAAs (US EPA 2009, OECD portal). The PFCA subcategory of long-chain PFAAs includes
PFOA (Figure 5), higher homologues, and their salts and precursors. The PFSA subcategory includes
D1.2
Copyright © TEXSHIELD Project Consortium 2013
5
perfluorohexane sulfonic acid (PFHxS), PFOS, higher homologues, and their salts and precursors (see
Figure 6).
D1.2
Copyright © TEXSHIELD Project Consortium 2013
6
Figure 5 Perfluorooctane sulfonic acid (CAS No: 1763-23-1).
Long-chain
PFCA
PFOA
Higher
homologues
Precursors
Salts
Long-chain PFSA
PFOS
Higher
homologues
PFHxS
Salts
Precursors
Figure 6 Categories and subcategories of long-chain perfluoroalkyl acids (PFAAs)
Source: United States Environmental Protection Agency (U.S.EPA).
Over time, DWR finishes with the long-chain chemistries on textiles can wear off. Intensive washing of
textiles increases the amounts of the finishes that are lost to the environment (Heckster, 2002). In the
course of their intentional use in products or unintended loss, long-chain PFAAs are released into the
environment in significant quantities. PFOA and PFOS are the most widely known and studied of the longchain PFAAs (Danish EPA, 2005).
As a result of their strong carbon-fluorine bonds, PFOA and PFOS do not readily break down in the
environment. They have been shown to be persistent in the environment and have long elimination half-life
in wildlife and in humans. Numerous reports have documented the presence of long-chain PFAAs in aquatic
environments in Japan, United States, Germany and Italy, with PFOA and PFOS comprising the most
detected chemicals (US EPA, 2009; Lin 2009). It should be noted that PFOA and PFOS can also be
unintentionally produced. For example, PFOA can be produced by degradation of other fluorinated
chemicals (US EPA, 2009). It can be found in consumer products as an impurity and unintended by-product,
and not as a deliberately added ingredient. This is particularly the case in products treated with
D1.2
Copyright © TEXSHIELD Project Consortium 2013
7
perfluoroalkyl-containing chemicals. In ecosystems and in living organisms, chemicals such as
perfluorosulfonamide can be biotransformed to PFOS (Tomy GT, 2004).
Since PFOA and PFOS are everywhere in the environment, exposure to these chemicals is also
widespread. PFOS was the predominant perfluorinated chemical found among Durable Water and Soil
repellent chemistry in the textile industry (Heckster, 2002).
b. Mode of operation
Commercial fluorochemical repellents are based on vinyl or acrylic polymers. These polymers have
perfluoro side chains that can orientate to the fibre surface and give a reasonably close packed surface of CF2- and -CF3 groups.
For example, acrylic acid can be reacted with a perfluoro alcohol to form the corresponding acrylate ester.
The acrylate monomer will polymerise to form a high molecular weight polymer that can be converted to an
emulsion. The emulsion dries to a continuous film, covering the fibre surface. The perfluoro segment is there
as a side chain attached to the polymer backbone. Being nonpolar, it will orient away from polar forces, thus
forcing itself toward the air interface. Heat facilitates the orientation by increasing molecular motion, hence
the need to iron (hot press) treated textiles after laundering to re-orientate the fluorocarbon chains at
achieve optimum repellence, Figure 7.
Figure 7 Schematic diagram of a fluorocarbon attached to a substrate illustrating heat facilitated reorientation.
c. Commercially available products
In line with the requirements of PFOA Stewardship Programme, there has been an orchestrated effort by
the industry to reduce global factory emissions and product content of PFOA by 2010, and to work towards
eliminating emissions and product content by 2015. Indeed since June 2013, both PFOA and PFCA have
been added to the candidate list for authorisation by REACH (Candidate List, June 2013).
Different organisations have adopted different strategies to meet the challenge. Some organisations have
introduced lower chain fluorocarbons. Others have developed alliances, innovative materials and processes.
DuPont and Huntsman Alliance:
DuPont has developed a range of water repellent and soil release finishes for textile use under the trade
name of DuPont™ Capstone™ products (Appendix 1). Capstone™ products which were introduced to the
marketplace in March 2009 are based on short-chain chemistry involving six or fewer fluorinated carbons
and meet the requirements of the US Environmental Protection Agency's (EPA's) 2010/15 PFOA
Stewardship Programme.
According to DuPont, Capstone products offered a step-change reduction in trace impurities of PFOA below
the limit of detection (essentially without compromising fluorine efficiency). Indeed a recent Green Peace
study reported that no PFOS were detected in their study (Green Peace Report, 2012).
D1.2
Copyright © TEXSHIELD Project Consortium 2013
8
Capstone has been sold to mills under the Huntsman trade name Oleophobol®. Once a licensed mill meets
performance specifications, its products is marketed to the consumer as DuPont Teflon® fabric protector.
Following the introduction of DuPont™ Capstone™ products, Huntsman Textile Effects, a division of
Huntsman Corporation launched Oleophobol® CP-R and CP-S environmentally friendly textile finishes.
Oleophobol® CP-R stain-release finish for cotton, man-made fibres and blends facilitates easier removal of
water- and oil-based stains during the laundering process. Oleophobol® CP-S oil-, water- and stainrepellent finish for man-made fibres and blends enables spills to be blotted up quickly with a clean, dry,
absorbent cloth. Oleophobol® CP-U, an oil, water and stain repellent finish designed for automotive and
upholstery applications was launched in 2012. Oleophobol® CP-U is also based on short chain chemistry
and developed through Huntsman-DuPont alliance.
In March 2013, Huntsman launched PHOBOTEX® range of rain protection and stain management products.
No detailed information on the nature of the chemicals has been disclosed. However, Huntsman claims the
product range is fluorine free and complementary to Phobol CP short-chain C6 fluorocarbons, sold under
the Teflon trademark.
In addition, in May 2013, Huntsman-DuPont alliance launched the “New PHOBOL CP” products for dual
action stain management on apparel. Again no detailed information is available. However, both PHOBOL
CP-DP and PHOBOL CP-DL are based on short chain fluoropolymers.
3M:
3M is one of the major players in the repellent market and Scotchgard® Brand name has been a household
name recognised for protection over 50 years.
Scotchgard® Brand fluorocarbons were originally based on C8 chemistry and, as mentioned earlier, 3M
voluntarily stopped the manufacturing and supply of C8 chemistry in May 2000.
The current 3M fluorochemical protective treatment products are based on C4 chemistry (3M, 2013) and
comply with EPA 2010/15 PFOA Stewardship programme.
Scotchgard® Brand of protectors for textiles, amongst others, includes:
i.
ii.
iii.
Stain release.
Repellents.
Repel and release.
Table 1 shows typical products marketed by 3M (full product list is available from 3M).
D1.2
Copyright © TEXSHIELD Project Consortium 2013
9
Table 1 Typical products marketing by 3M
Product
Type of
Protection
End use
Used for
Application
method
Claims
PM-490
Stain
release,oil
repellency
and water
resistance
Stain
release,oil
repellency
and water
resistance
Durable
stain
release, oil
and water
repellency
Cellulosics
and blends
Home
fasion
Pad/dry/cure
Stain release,
Durable protection
Breathable fabric
Prolongs fabric life
Cellulosics,
synthetics
and blends
Home
fasion
Durable
stain
release, oil
and water
repellency
Cellulosics,
synthetics
and blends
Home
fasion
Durable
finish, oil
and
dynamic
water
repellency
Durable
stain
release
Oil and
water
repellency
Cellulosics,
synthetics
and blends
Home
fasion,
Outerwear,
upholstery
Pad/dry/cure
Cellulosics,
synthetics
and blends
Variety of
applications
Pad/dry/cure
PM-492
PM-900
PM-930
PM-3633
PM-938
Curing temp
150-180 deg C
Cellulosics
and blends
Home
fasion
Pad/dry/cure
Curing temp
150-180 deg C
Pad/dry/cure
Curing temp
140-190 deg C
Pad/dry/cure
Curing temp
130-190 deg C
Curing temp
130-190 deg C
Curing temp
150-180 deg C
Stain release,
Durable protection
Breathable fabric
Prolongs fabric life
Exceptional stain
protection
Stain release and
repellency
Durable protection
Breathable fabric
Exceptional stain
protection
Stain release and
repellency
Durable protection
Breathable fabric
Highly water
resistance
Wash durable
Breathable fabric
Water repellent
Resist stain
Durable stain
release
Oil and water
repellency
DAIKIN:
Daikin is a major manufacturer for fluorocarbons. Unidyne is the trade name for water and oil repellent
products marketed by Daikin. Appendix II shows the list of Unidyne C8 and C6 (six carbon atoms in the
fluorocarbon polymer chain) fluorocarbons marketed by Daikin.
Asahi:
Asahi has offered both fluorinated and silicone repellent finishes to the marketplace for the past 35 years
under the trademark Asahi Guard®. However, the fluorinated products were based on long chain chemistry
and released small quantities of PFOA to the environment.
Asahi has now introduced Asahi Guard® E-Series which are based on shorter chain fluorinated chemistry
and is claimed to offer the same performance level as the long chain chemistry but without the release of
PFOA and its precursors to the environment.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
10
Asahi Guard® E-Series for textiles market include AG-E092, AG-E082, AG-E061. These are all applied by
pad-dry-cure processing. The crosslinking could be done either by a melamine resin and a catalyst or by a
isocyanate cross-linking agent at 150-170 deg C.
BASF:
BASF introduced Lurotex® Duo Systems. These are based on C6 technology and marketed as Lurotex®
Protector RP ECO (for the repellent market) and Lurotex® Protector RL ECO fluorocarbon finishes( for the
release market).
Lurotex Systems are composed of two components, a C6 fluorocarbon finish and an unblocked isocyanate
booster called Perapret® Booster XLR. Obviously due to the reactive nature of the unblocked isocyanate,
Perapret® Booster XLR reacts at much lower temperatures with a variety of substrates (including cotton and
synthetics and their blends and the treated textiles show reduced yellowing without adverse effects on
physical characteristics of the fabric.
RUDOLF Group:
Rudolf Group offers a wide range of C8 and C6 fluorocarbons both as water dispersions and solvent based
systems. In addition, they offer silicone and alternative innovative repellent technologies which will be
discussed later.
The Brand name for Rudolf’s repellent products are Ruco-Guard, Rucostar, Ruco-dry, Ruco-coat, Ruco,
Ruco-protect and Rucotec. Table 2 below shows the range of Rudolf’s repellent products for the textile
market:
Table 2 Rudolf’s repellent products
Trade name
RUCOGUARD®
Products
Water or solvent-based fluorocarbon polymers, fluorocarbon resins or
boosters for water, oil and soil-repellent impregnations of surfaces
RUCOSTAR®
Water-based FC products for water, oil and soil-repellent impregnations of
surfaces with reduced fluorocarbon portion
RUCO-DRY®
Water-based FC-free products for water and soil-repellent impregnations,
no oil repellency, post-impregnation of surfaces
RUCOCOAT®
RUCO®
Water or solvent-based FC or FC-free products for water, oil and soilrepellent impregnations of surfaces
Water or solvent-based FC or FC-free products for post-impregnation,
waterproofing, textile care and other surfaces
RUCO-GUARD® and RUCOSTAR® are aqueous C6-based fluorocarbon polymeric dispersions. Aqueous
systems usually require additional curing after drying. This is to ensure maximum water, oil and soilrepellent effects. As mentioned before, during the heating process the initially unordered perfluorinated side
chains of FC products are oriented towards the air at the interface, and crosslinking processes are set off.
This activates and simultaneously fixes protective properties.
Clariant:
Clariant is a large manufacturer of speciality chemicals with well established C8 based durable fluorine
repellents marketed under Nuva® brand name. In order to comply with EPA PFOA 2010/2015 Stewardship
D1.2
Copyright © TEXSHIELD Project Consortium 2013
11
programme, Clariant has focused on the development of C6 chemistry which is marketed under Nuva-N
range of products since 2006.
Nuva-N range is based on C6 technology and is a durable finish which is applied by pad/dry/cure
processing.
More recently Clariant launched Nuva N1811. This is a C6-based micro-encapsulated technology believed
to be more efficient and improves some of the physical characteristics of the treated fabric e.g. fabric
handle, sewing-ability, abrasion and tear resistance with similar repellency performance as the existing C6
products.
Nuva 1811, Nuva N2114 and Nuva N2155 all meet the Bluesign1 criteria.
Clariant offerings include a fluorine-free water repellent durable finish called krophob FFR. This is claimed to
outperform other fluorine-free products (in terms of water repellence) and its performance is close to that of
C6 fluorine based finishes.
The active ingredient and the special formulation of krophob FFR is closely guarded and, when applied
correctly meets the bluesign criteria.
ZSCHIMMER & SCHWARZ:
Established in 1894, ZSCHIMMER & SCHWARZ is a family owned medium size chemical manufacturer
based in Germany. ZSCHIMMER & SCHWARZ fluorine based water and oil repellents are marketed under
the Anthydrin brand.
The bulk of their fluorocarbon resins are still based on conventional C8 chemistry. These include Anthydrin
TA, Anthydrin NHP, Anthydrin LAD and Anthydrin FOB conc.
ZSCHIMMER & SCHWARZ C6 fluorocarbon offerings include Anthydrin SC and Anthydrin SCE. These are
based on C6 chemistry and comply with the stewardship programme.
All the Anthydrin products are supplied in emulsion form and applied by pad/dry/cure process. Anthydrin is
cured at 150-170˚C and the treated fabric is resistant to washing and dry cleaning.
Protex Korea:
Protex is a relatively small manufacturer specialising in fine chemicals established in 1990. Protex offering
for water and oil repellent market is called DRYOL FOX Conc.
DRYOL FOX Conc is fluorocarbon supplied in an emulsion form which is applied by pad/dry/cure
processing.
No information is available on the nature of fluorocarbon.
Protex offer DRYOL XFL for water repellent market. This is a paraffin wax emulsion applied along with a
flourocarbon resin extender. Again no detailed information was found on the nature of the fluorocarbon used
and there is no mention of EPA PFOA 2010/2015 Stewardship programme.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
12
CHT:
CHT is a middle sized family owned chemical manufacturer established in 1953. CHT has a number of
water and oil repellent and soil release finishes marketed under the brand name Tubiguard®. Currently CHT
offers both C8 and C6 fluorocarbon finishes which can be applied by padding application, foam application
or spray application. Regardless of the method of application, the treated fabric is dried at 100-120 deg C
and cured at 150-170 deg C to achieve high durability.
Tubiguard® 21, 270, 68, 55, 44N, SR 2001, Apyrol FCR-2 and Beiphob NFP are all based on C8 chemistry.
CHT’s C6 fluorocarbons are market under Tubiguard® F-series. The F-Series product offerings include
Tubiguard® 90-F, 86-F, 10-F, FA-F and NFC.
Currently CHT is working to develop low temperature cure short-chain fluorocarbons. However this is still in
the development stage.
More recently CHT has introduced ZeroF 1. ZeroF 1 is marketed as a “fluorine-free” finish which can be
applied and cured in a similar manner as mentioned above. ZeroF 1 fulfills the bluesign criteria.
Texchem:
Texchem is a small company established in 1978 offering a number of products and services to the industry.
Texchem product offering includes Texfin® C6-D, Texfin® USRC.
Texfin® C6-D is a C6 based durable water repellent applied by pad/dry/cure processing. Curing is done at
160 deg C for 1-2 minutes.
Texfin® USRC is a C6 based soil release finishing applied in a similar manner. Both products have PFOA
below the detection level.
d. Performance/advantages
The most important advantage of fluorocarbons is that they can provide the substrate with the lowest
surface energies of all repellent finishes in the marketplace. They can be formulated to have a durable finish
and can be water and oil repellent.In addition, fabrics treated with fluorocarbons allow improved soil release
during household laundering and show more rapid drying characteristics (Buck, 1998).
e. Disadvantages
The most important disadvantage of fluorocarbons are their adverse affect on the environment. As a result
of their strong carbon-fluorine bonds, PFOA and PFOS do not break down in the environment. They have
been shown to be persistent in the environment and have long elimination half-life in wildlife and in humans.
Numerous reports have documented the presence of long-chain PFAAs in aquatic environments in Japan,
United States, Germany and Italy, with PFOA and PFOS comprising the most detected chemicals (US EPA,
2009; Lin 2009).
Other disadvantages of fluorocarbon repellents include high cost, need for special treatment of waste water
from application processes, and greying during laundering.
3.3 Silicones
Silicone water proofing agents generally come in two forms:
i.
Elastomeric poly dimethylsiloxane. In this case the polymer adheres to the substrate and cure to form a
flexible protective membrane.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
13
ii.
Penetrating water repellent chemicals. These are reactive silanes and siloxane resins with crosslinkable
side chains. These materials have smaller molecular structures, which enable them to penetrate deeply
into the substrate, where they chemically bond with it.
Either of these materials can be delivered via solvent or aqueous emulsions. Figure 8 shows how the polar
main chain is shielded by the methyl groups.
Figure 8 A three-dimensional view of Me3SiO-(SiMe2O)4-SiMe3.
Table 3 Typical functional groups
Group
Alkyl
Amino
Alkoxy
Hydroxyl
Hydrogen
Typical Functional Groups for Penetrating Water Repellents
Position
Reactive
Function
A* or B**
No
Water Repellency
A* or B**
No
Catalytic
A* or B**
Yes
Cross-linking
A*
Yes
Cross-linking
B**
Yes
Cross-linking
A*: Terminal position and B**: Side group
The above table shows some typical functionalities but the subject matter could be derivatised to have a
wide range of functionalities including acrylic, vinyl or epoxy functionalities for a wide range of applications.
a. Mode of operation
Silicones have low surface tension, which enables them to spread and soak easily into a substrate’s pores.
Their highly flexible and mobile siloxane backbone (see Figure 9 below) provides the ability to form
hydrogen bonds with fibres and enables the water repelling groups eg methyl or alkyl groups to orient
themselves towards the surface of the substrate creating water proof surface.
Figure 9 Schematic diagram of polydimethyl siloxane.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
14
Conventional silicone technologies rely on forming a thin film on the surface of the textile substrate which
prevent water droplets penetrating whilst allowing water vapour to permeate and so enabling the textile to
“breathe”. Early silicone treatments deposited relatively thick layers which reduced the breathability of the
textile making the treated textiles less comfortable to the wearer over prolonged periods.
Research in this field has resulted in the development of new reactive molecules and delivery methods that
allow the silicone to be deposited as an ultra-thin layer around individual fibres, filaments or yarns before
covalently bonding on the surface of the fibre at the reactive sites. Consequently these treatments do not
adversely affect the breathability of the finished product and maintain an enhanced level of comfort. EPIC
from Nextec is an example of such products in the marketplace.
Polydimethylsiloxanes (PDMS) are the most common silicone repellents. They form hydrogen bonds with
fibres and exhibit repellency effects on the outer surface of fibres. They have only moderate durability to
laundering and dry cleaning, and no oil and soil repellency.
Silicone repellents designed to be durable finishes generally consist of a silanol, a silane and a catalyst such
as tin octoate. The silanol and silane components react to form a three-dimensional cross-linked sheath
around fibres and the catalyst promotes alignment of the silicone film on the fibre surface, with the outward
positioned methyl groups of the silicone polymer generating the water repellency effects.
PDMS has also been used to make super-hydrophobic surfaces. Various methods have been used to make
super-hydrophobic surfaces with PDMS. Khorasani et al (2005) modified the surface of PDMS using a CO2
pulsed laser as an excitation source and introduced peroxide groups onto the PDMS surface. These
peroxides groups could then react with 2-hydroxyethylmethacrylate (HEMA) producing a graft copolymer
with PDMS. They reported water contact angle (WCA) of the treated PDMS was 175˚. The reason for such
an increase in WCA was reported to be due to the porosity and chain ordering on the surface of PDMS.
b. Commercially available products:
Dow Corning®:
Established in 1943, Dow Corning® is a £1.75 billion global company with nearly 9000 employees
worldwide. Focusing on silicone chemistry and with thousands of products, Dow Corning has a strong
presence in a wide range market segments including textile finishing and auxiliaries. Dow Corning repellent
product offerings also include fluoro-silicone (FS) and organic repellents (OR). Table 4 shows a number of
such products.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
15
Table 4 Available products from Dow Corning®
Product
Dow Corning® ET 4327
Emulsion
Dow Corning® LS 4325
Dow Corning® LS 4326
Dow Corning® GSD 7000 Soft
Protection Technology
Dow Corning® 732
Dow Corning® 734
Dow Corning® Q3-7246Textile
RTV
Dow Corning® 2634 Coating
XIAMETER® RBL-9252-250 P
Dow Corning® 3631 Part A&B
Dow Corning® 1-6184
Dow Corning® 84 additive
Dow Corning® 85 additive
Dow Corning® 772
Dow Corning® 777
Dow Corning® Z 2306 Silane
Dow Corning® Z 6341 Silane
Dow Corning® Z 6403 Silane
Dow Corning® Z 6585 Silane
Dow Corning® Z 6595 Silane
Dow Corning® Z 6665 Silane
Features/benefits
Emulsion based water repellent
Solvent based, condensation cure water repellent
Solvent based, condensation cure water repellent
Durable water repellent finish with excellent softness for
outdoor active wear offering more than 30 washes to cotton
blends
Silicone fabric coating
Silicone fabric coating
Silicon Fabric coating
Dow Corning Clean Surface Coatings alkoxysilane functional
perfluoropolyether (PFPE) hybrid polymers).See hybrids
Sportswear high grip coating eg glove coating
Narrow fabric coating high grip application
Water repellent, described as alkoxy silane and composed of
90%
methoxy
terminated
silsesquixanes
plus
5%
methyltrimethoxy silane
Water repellent/Water based
Water repellent/Water based
Water dilutable sodium methylsiliconate water repellent
Water dilutable potassium methylsiliconate water repellent
Isobutyltrimethoxy silane water repellent
Octylsilane water repellent
Water repellent
Hexyltriethoxysilane water repellent
Blend of n-octyltriethoxysilane and reactive silicone
Octyltrimethoxysilane-based hydrophobing agent
Shin-Etsu Chemicals:
Shin-Etsu Chemicals was established in 1926 and entered to silicones over 40 years.
Shin-Etsu is a major player in a wide range of silicone market including textiles. Appendix III shows their
product list for water repellents for textiles.
Wacker Water-Repellent and Breathable Textile Finishing:
Water-repellent treatment is a standard finishing process for modern textiles. WACKER’s water-repellent
agents exploit the high water repellency of silicones without impairing the textiles' ability to breathe. For
example Wacker HC 303 is a finely dispersed water based silicone emulsion based on aminofunctional
PDMS particles typically 25 nm in diameter. The The repellent finish can be applied by impregnation or by
spraying followed by drying and curing.
Repellent finishes are usually composed of a number of active substances and the exact nature of the
formulations are not usually disclosed. For example, Wacker HC 303 in addition to PDMS also contains the
following:
i. Poly[3-((2-aminoethyl)amino)propyl]meth l(dimethyl)siloxane, hydroxy-terminated.
ii. Diethyleneglycol monobutylether.
iii. Ethylene glycol monohexyl ether.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
16
iv. Octamethylcyclotetrasiloxane.
The finish is semi-durable and claimed to be less affected by washing and cleaning than the conventional
PDMS. Additionally, they confer a soft hand on textiles.
Wacker finish WS 60 E is a macro-emulsion which is applied in combination with a catalyst i.e. catalyst C38
by spraying or padding. The finish provide optimum water repellency.
Wacker Finish CT 51 L is a high polymer, silicone solution that crosslinks rapidly to form flexible silicone
films when activated by Curing Agent V 80 and Catalyst C 80 and heat. The finish produces a flexible, rubresistant and waterproof coatings on all kinds of textile fabrics.
c. Performance/advantages
Fabrics treated with silicones achieve a high level of water repellence and water proofing properties, see
Figure 10. Whilst durability of silicones is often low some have been formulated to give good wash durability
with some manufacturers reporting durability of 30 washes at 40˚C.
Figure 10 Fabric treated with silicone water-repellent finish.
Silicones have high spreading and wetting capability. This characteristic gives the silicone the ability to
thoroughly cover a surface or penetrate a porous substrate and could be formulated to have high wash
durability.
In addition fabrics treated with silicone demonstrate good permeability to gas and water vapour, resistant to
UV, heat and oxidative degradation.
Due to the flexible nature of the molecules, fabrics treated with silicone have good drape, fabric handle and
workability.
Silicone finishes are generally more environmentally friendly and cheaper than fluorocarbons.
d. Disadvantages
i. Environmental
A large number of studies have been conducted to evaluate the fate and effects of silicones in the
environment throughout their life cycle (EC Ecotoxicology report, 1994). Releases to the environment from
the manufacture of polydimethylsiloxane (PDMS) are strictly controlled and must comply with emission limits
specified by regulatory authorities. Subsequently, the environmental fate of silicones depends to a large
extent on the nature of the application, the physical form of the material and the method of disposal. Low
molecular weight PDMS polymers (< 1000 Da) are primarily used in personal and household care products.
High molecular weight PDMS polymers are important as antifoams and lubricants for domestic and
industrial use such as textile applications. However, a more important application is as a “solid” silicone
D1.2
Copyright © TEXSHIELD Project Consortium 2013
17
such as PDMS-based rubbers or sealants, both of which may be used either in the home or diverse
industrial applications such as textile coatings, electronics, silicone mouldings and rubber gaskets.
“Solid” silicones enter the environment as a component of domestic or industrial waste and will be either
land filled or incinerated. In the latter case, they are converted back to inorganic ingredients, amorphous
silica, carbon dioxide and water vapour. “Liquid” silicones, both high and low molecular weights, which are
used in rinse-off products such as shampoos, hair conditioners or silicone antifoams in detergents, become
part of municipal wastewater. The same is true for PDMS used as antiflatulents in pharmaceuticals. High
molecular weight silicones are virtually insoluble in water, thus, as a consequence of their high binding
potential for organic matter, they are effectively removed from municipal wastewater onto the sludge during
wastewater treatment. Extensive studies show that more than 95% of silicones are removed from effluents
in this way, and that the concentration in discharged effluents are in order of 5 µg/l (Watts, 1995; Fendinger,
1997).
ii. Functional
Silicones do not resist oil borne stains. Adsorption of hydrophilic substances found in dry cleaning and
laundry products could impair water repellency. In addition, silicone finishes are less durable than
fluorochemical finishes and more expensive than wax repellents.
3.4 Hybrids/nanoparticle approach
Daikin has developed UNIDYNE Multi-Series in an alliance with Dow Corning. The technology combines
and utilises the benefits and advantages of both the fluorine and silicone technologies to deliver a combined
oil, water and soil release finish for textiles. Although PFOA content of Unidyne Multi-Series is less than 5
ppb, it is claimed to be a fluorine free product. Figure 11 below shows a schematic depiction of the finish on
the fibre.
Jointly developed by Daikin and Dow Corning
Figure 11 Schematic depiction of a flurorosilicone finish on the fibre.
Table 5 shows a list of Unidyne Multi-series products which is applied by padding-drying-curing process.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
18
Table 5 Unidyne Multi-series products
Multi Series
Form
Ionicity
Features
TG-5601*
Water-based
emulsion
weak cation
Gives both extreme soft hand-feel and high
wash durability via silicon hybrid technology.
TG-5541*
Water-based
emulsion
weak cation
Gives soft hand-feel and extreme high water
repellency via silicon hybrid technology.
TG-5543*
Water-based
emulsion
weak cation
Gives extreme high wash durability and high
soft hand-feel via silicon hybrid technology.
TG-5502
Water-based
emulsion
nonion
High water bearing pressure and high alcohol
resistance. Especially good for polyolefin
nonwoven texture.
TG-8111
Water-based
emulsion
anion
Gives high oil and grease resistance to paper
products. Suitable for external melt (size
press) and coating. Also suitable for internal
melt (acquired FDA).
*UNIDYNE TG-5601 TG-5541 TG-5543 is a joint development product between Daikin and Dow Corning.
The active components of all the above products have been defined as “fluoroalkyl copolymer” in the
relevant MSDS’s.
Bionic finish from Rudolf Group: RUCOSTAR product range:
The Rudolf Group has developed a range of C6-modified fluorocarbon products by incorporating
hyperbranched dendrimers branded as BIONIC-FINISH® with RUCOSTAR®.
In addition to fluorocarbon polymers, RUCOSTAR® products contain RUCOSTAR® dendrimers. During the
treatment process, a self-organisation takes place, in which fluorocarbon polymers are actively enriched on
the surface by means of the dendrimers and forced to co-crystallise as shown in figure below. It is claimed
that the sandwich structures obtained are highly ordered resulting in equal or better effects with significantly
lower fluorocarbon quantities compared to a conventional FC-finish.
Figure 12 Schematic diagram of textile fibre treated with RUCOSTAR.
Nano technology
D1.2
Copyright © TEXSHIELD Project Consortium 2013
19
Nano technology has the potential to have a huge impact on the textile industry. Coating the surface of
textiles and clothing with nano-particles is an approach to the production of highly active surfaces to provide
UV blocking, antimicrobial, flame retardant, water repellent and self-cleaning properties, Figure 13.
Figure 13 Schematic images illustrating the potential for nanotechnology.
NanoSphere®
Schoeller Technology has developed a self-cleaning surface finish marketed as NanoSphere®. The
nanotech-based finishing imparts water, oil and soil repellency to fabric. This is achieved by creating a finely
structured topography on the surface as shown in Figure 14.
Schoeller Technology describe the treatment as providing water, oil and dirt repelling properties. They also
claim NanoSphere® treated textiles are better and the finish is more wash durable than the traditional textile
finshing processes and the comfort level is not affected by washing (Schoeller Technology, 2006).
Figure 14 Schoeller Technology images illustrating the difference in water droplet shape on a a classic
(planar) surface (left), and their Nanosphere® treated surface (right).
D1.2
Copyright © TEXSHIELD Project Consortium 2013
20
ecorepel®: an ecological approach to repel water and mud
ecorepel® finish from Schoeller Technology is also biomimetic in concept. The approach for this technology
is based on long paraffin chains that wrap themselves spirally around individual fibres, filaments or yarns in
a very fine film, Figure 15. This reduces surface tension so that water droplets and even mud with
significantly higher surface tension simply run off. The breathability is not affected and the feel is reported as
being soft.
Figure 15 Product illustration for ecorepel®.
Plasma Treatment
Low-temperature plasma technology - both glow discharge under reduced pressure as well as barrier
discharge under normal pressure - are well established in different industrial applications. Due to practical
difficulties the introduction of plasma technology in the textile industry was initially slow. However, the pace
of exploitation of this technology in the this industry has accelerated in recent years and the fields of
applications include desizing, functionalising, and design of surface properties of textile fibres.
Plasma technology can modify the chemical structure as well as the topography of the surface of the
material. The general reactions to be achieved by plasma treatment are the oxidation of the surface of a
material, the generation of radicals, and the edging of the surface; when using special gases a plasmainduced deposition polymerization may occur.
For the treatment of textiles this means that fabric surface could be made hydrophilic or hydrophobic as
required. Moreover, both the surface chemistry and the surface topography may be influenced to result in
improved adhesion or repellency properties as well as in the confinement of functional groups to the
surface.
Plasma treatment has to be controlled carefully to avoid detrimental action of the plasma onto the substrate,
the technique well utilised by Dow Corning in offering Plasma Solutions next.
Dow Corning Plasma Solutions
Dow Corning has developed a plasma treatment process which can be carefully controlled and can produce
nano-coating-based solutions to customers in many industry sectors including textile, nonwoven paper, foil,
medical, automotive, electronics, sensor and environmental.
The process is carried out under atmospheric pressure which can be used in a continuous in-line textile
production plant. This is a very efficient way to deliver a thin layer of various finishes including silicone or
fluorosilicone to a verity of substrates.
D1.2
Copyright © TEXSHIELD Project Consortium 2013
21