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SILICONE SOFTENERS FOR STAIN REPELLENTAND

STAIN RELEASE FABRIC FINISHING

Fernando Vazquez

Dow Corning Corporation

Greensboro, N.C.

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ABSTRACTDuring the last few years the use of fluorochemicals to

provide stain repellency and/or stain release properties to

apparel goods has rapidly grown. The use of

fluorochemicals as well as durable press resins, however,

has a detrimental effect on the fabric softness. Providingpremium softness is key to satisfy the highly demanding

aesthetic requirements of many of today’s apparel

products. Although softeners based on conventional

aminofunctional silicones are well known to provide

excellent hand, they significantly impair both the stainrepellency and the stain release properties of

fluorochemical treated fabrics. This paper presents the

results from a recent study where current and new selected

organo-modified silicones provide very good softness with

minimum–to–no impact on the fluorochemical properties.

INTRODUCTIONDuring the last few years the “easy care” concept has

rapidly expanded to include “stain resistant” features in

many apparel applications. The easy care concept now

encompasses both minimization of ironing and easiness to

clean garments that might have become stained in

everyday use. The use of finishes that provide stain

release and stain repellency to apparel fabrics, particularly

cotton, has shown an amazing growth during these last

years. 1, 2

Fabric manufacturers and chemical manufacturers have

made advances in finishing processes to ease stain

removal and prevent stain penetration. Today, stain

release finishing for apparel cotton fabrics is mostly

imparted by the incorporation of low surface energyfluorochemicals. Stain release fluorochemical finishes

allow oil and water stains to penetrate the fabric; however,

when the fabric is laundered, the stains are easily

removed. 3 Fluorochemicals also dominate the stain

repellency textile apparel market. Out of all existing

textile chemicals, only fluorochemicals have shown the

unique property to provide fabrics a low surface energy

film with both high oil and water repellency properties to

resist penetration of oil and water-based stains (polar and

non polar liquids). The “repellent” products prevent the

textile substrate from wetting and soiling by repelling the

soiling substances and the adhesion of dry soil. 4 Fluorochemical hybrid finishes, also called “dual effect”,

which contain hydrophilic groups, have also been

developed and improved successfully over the most recent

years to impart both stain repellency and stain release

properties.

Most fabrics finished with durable press resins and

fluorochemicals have, however, an important drawback;

their handle is generally not acceptable and actually ca

be considerably harsh. Although selected conventiona

organic softeners can be used in these systems t

overcome this issue, the degree of softness they ca

provide has fallen short for many apparel applications

This is particularly true with today’s high performanc

and durability requirements where normally higher level

of finishing chemicals are used, which in turn, results in

higher detrimental effect on the fabric handle. Eve

higher levels of conventional organic softeners may no

give the softness level required or these levels may have

negative effect on the stain repellency or releas

properties, not evident when lower levels where used. I

addition to performance requirements, today’s highl

productive and complex finishing operations require th

use of “easy to use” and “trouble free” finishing product

that can offer stability over a broad range of proces

conditions and compatibility with most textile chemicals.

Thus, the selection of the right softener in order to achiev

both premium hand and optimum processability become

extremely important.

SILICONE SOFTENERS FOR FLUORO

CHEMICAL TEXTILE FINISHINGSilicones, particularly amino-modified silicones, are we

recognized as premium fabric finishing agents as they no

only provide unsurpassed softness but also improve man

fabric physical properties. 6, 7 However, conventiona

aminofunctional silicones have shown to impa

significantly both the stain repellency and the soil releas

properties of most fluorochemical treated fabri

substrates.

During the last several years, specialty organo-modifie

silicones have been used in stain release and stai

repellency textile finishing, imparting various degrees o

softness without degrading significantly the propertie

provided by fluorochemicals. These materials ar

generally silicone copolymers or terpolymers and hav

chemical structures where hydrophilic groups, such a

polyalkylene oxide polymers, are arranged in differen

ways onto the main siloxane backbone. These organo

modified silicone polymers may also contain additiona

reactive organic groups, such as amines, amides an

epoxides, which normally contribute to the softness and/odurability.

Most recently, modified versions of the above as well a

new silicone chemistries are being introduced which offe

improved softness coupled with the benefit of no

impacting the stain repellency and/or stain releas

properties. More interestingly, some of these silicone

have even shown synergistic effects, which result i

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improvements of the properties provided by the

fluorochemicals.

In addition, some of these selected organo-modified

silicones are water dispersible or soluble which make

them extremely stable in most extreme textile finishing

conditions and also compatible with most textile

chemicals.

EXPERIMENTALThe effect of several selected organo-modified silicones

on stain release and stain repellency properties were

evaluated. The silicone softeners included in the study

were: 1) Conventional aminosilicone (microemulsion),

2) Reactive silicone copolymer (currently used in the

application), 3) Silicone terpolymer and 4) New silicone

copolymer. Water based emulsions and/or dispersions

were prepared containing 20% actives of each of the

silicones listed above.

The finishing bath consisted of the silicone softener

emulsion, a fluorochemical emulsion, a durable press

reactant and its catalyst, and a non-rewetting wetting

agent. The bath formulation is shown in Table 1. The

systems were applied to khaki cotton twill (8 oz/sqyd) and

to bleached 65/35 polyester/cotton broadcloth. In

addition, a 100% interlock cotton knit was also included in

the stain repellency study.

The fabrics were treated by padding (65% Wet pick-up)

and dried/cured at 170oC for 90 seconds. A fluorinated

urethane polymer was used for the stain release finishing

whereas a fluoroacrylate copolymer was used for the stain

repellent finishing.

For the stain release testing, finishing formulations were

designed so that 1% silicone solids and 1% fluorochemical

solids were added on both fabrics. For the stain

repellency testing also 0.5% silicone add on was used.

The reasons behind using relatively high quantities of

silicone on fabric were that, first, the real impact of these

silicones on the fluorochemical properties wanted to be

determined and lower levels might have hidden their

potential impact, and second, the high amounts of

finishing chemicals such as durable press resins and

fluorochemicals being used in some applications may

require higher levels of silicone softener in order to satisfy

premium softness requirements.

Stain release performance was assessed using AATCC

method 130-2000. Fabrics were stained with three types

of oily soils, dirty motor oil, mineral oil and vegetable oil

(Wesson® corn oil) and rated after one home laundering

tumble-dry cycle (HLTD). On the other hand, stain

repellency performance was assessed by measurin

fabric’s oil and water repellency using AATCC method

118-2000 and 22-2000 respectively. Softness wa

evaluated through a hand panel where evaluators rated th

fabrics by giving 5 points to the softest and 1 point to th

least soft. The average rating was recorded.

Table 1. Finishing Bath FormulationProduct % Weight

Silicone Emulsion (20% actives) 7.7

Fluorochemical Emulsiona 5.0

Durable Press Reactantb 12.0

Durable Press Catalyst 3.0

Wetting Agentb 0.1

Water Balance Balancea. Both the stain release fluorochemical and the stain repelle

fluorochemical have 30% total solids.

b. Buffered glyoxal reactant, 40% solids.c. A non-rewetting surfactant type was used for the stain repellent finish

RESULTS:

STAIN RELEASE FINISHINGTable 2 shows the stain release ratings of untreated an

treated fabrics after 1 HLTD cycle. As expected, thconventional aminosilicone had a significant impact o

the stain release properties of both the cotton twill an

polycotton woven fabric.

On Cotton Twill, the stain release ratings dropped 1.2 1.4 points when this fabric was treated with th

aminosilicone as compared to the fluorinated urethan

treated fabric. In contrast, the cotton twill treated with th

selected organo-modified silicones showed minimum–to

no impact on the stain release properties provided by th

fluorinated urethane polymer. The differences in stai

release ratings between the selected organo-modifie

silicones and the fluorochemical only-treated fabrics g

from a decrease in 0.3 units (reactive copolymer/vegetabl

oil) to an improvement of 0.4 units (new copolymer

motor oil). The new silicone copolymer actually showthe best average performance as compared to th

fluorochemical only-treated cotton twill. As anticipated

all silicones improved the softness of th

resin/fluorochemical treated-only fabric. The new silicon

copolymer also provided very good softness, better tha

any of the other silicone polymers designed for th

application and not far from that provided by th

aminosilicone.

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Table 2. Stain Release Ratingsa of Fabrics Treated with

Organo-modified Silicones and Fluorinated Urethane

Product Dirty

Motor

Oil

Vegetable

Oil

Mineral

Oil

Softnessb

Khaki Cotton Twill

FC Only 2.2 4.5 3.8 1

FC +

Aminosilicone1.0 3.3 2.0 5

FC + Reactive

Silicone

Copolymer

2.2 4.2 3.7 3.7

FC + Silicone

Terpolymer2.3 4.5 3.7 3

FC + New

Silicone

Copolymer

2.6 4.3 3.7 4.4

65/35 Polycotton Broadcloth

FC Only 2.3 5 4.3 1

FC +

Aminosilicone1.0 3.6 3.5 5

FC + Reactive

Silicone 1.3 4.4 3.7 4.5

FC + Silicone

Terpolymer1.9 4.8 3.8 4.5

FC + New

Silicone

Copolymer

1.8 4.7 3.8 4.0

a. Ratings according to AATCC 130- 2000.

b. Average rating from hand panel evaluation where 5 = Softest, 1 = Leastsoft/harshest.

On the 65/35 polycotton fabric, the impact of the selected

organo-modified silicones on the stain release properties

was higher than that seen on the cotton twill but still

shows a very important improvement as compared to that

obtained when the fabric is treated with the aminosilicone.

The selected organo-modified silicones impacted the stain

release ratings 0.1-1 points. Both the terpolymer and the

new silicone copolymer also showed the best performance

with stain release ratings only about 0.4 points (on

average) higher, respectively, than those obtained with thefluorochemical only-treated fabric. As expected, softness

was again improved with the addition of all the silicones.

Although the best softness was obtained with the

aminosilicone, both the reactive silicone copolymer and

the terpolymer were very close. The new silicone

copolymer provided a good hand improvement as well,

however, this was perceived relatively inferior to that

provided by the other two silicones designed for the

application.

STAIN REPELLENT FINISHINGTable 3 shows the stain repellency performance of th

treated fabrics, measured as a function of oil and wate

repellency. As expected, the conventional aminosilicon

had a significant impact on oil repellency of both thfabrics. Overall, oil repellency rating differences for th

aminosilicone went from 3.5 (for polycotton) to as high a

6.5 points (for the cotton fabrics) when compared to th

fluorochemical only-treated fabrics.

On cotton twill, the selected organo-modified silicone

showed little-to–no impact on the oil repellent propertie

provided by the fluoroacrylate copolymer. Th

terpolymer gave the best performance as far as impact o

the oil repellency provided by the fluorochemical. Th

new silicone copolymer provided the second bes

performance impacting the oil ratings only 0.5-1 points.

As far as water repellency is concerned, the reactiv

silicone copolymer gave the best performance on cotto

twill and actually slightly improved the water repellencprovided by the fluoroacrylate copolymer alone. Whe

compared to the fluorochemical treated-only fabric, bot

the silicone terpolymer and the new silicone copolyme

show some impact on the water repellency. In both case

the water repellency performance drops as the silicon

added on increases. This is also true for th

aminofunctional silicone.

All the silicones improved the softness of th

resin/fluorochemical treated-only fabric. The reactiv

silicone copolymer provided the best softness among th

organo-modified silicones and the second best overaafter the aminosilicone. On this fabric, the new silicon

copolymer provided the second best softness at 1%

silicone add-on level and only 0.5 points away from th

aminosilicone. Overall, the reactive silicone copolyme

provided the best balance of properties on cotton twill.

On 65/35 polycotton, the results for all the three organo

modified silicones were very good. The impact on eithe

oil repellency or water repellency was practically non

existent. The silicone terpolymer seemed to performslightly better than the others in terms of the oil repellenc

impact on this fabric. It is interesting to notice that for thpolycotton and cotton knit fabrics, the higher the amoun

of the new silicone copolymer, the better the oil repellenc

rating.

The softness provided by the three organo-modifie

silicones was similar for the 0.5% silicone add-on levels

yet inferior as compared to that provided by th

aminosilicone. Overall, the reactive copolymer was th

closest to the aminosilicone. For the 1% add on levels, th

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softness gap between the amino silicone and the other

organo-modified silicones broadened showing rating

differences of as much as 2.5 points. In this particular

case, the new copolymer did not provide as good softness

as that obtained on the cotton twill.

Table 3. Stain Repellency Performance using

Organo-modified Silicones in a Fluoroacrylate Copolymer System

Oil Repellencya

Water Repellencyb

Softnessc

Product 0.5 %Silicone

1%Silicone

0.5 %Silicone

1 %Silicone

0.5 %Silicone

1 %Silicone

Khaki Cotton Twill

FC Only 7.0 7.0 97 97 1.3 1.3

FC +

Aminosilicone1.0 1.5 75 50 4.6 4.4

FC +

Reactive

Silicone

Copolymer

6.0 6.0 100 100 4.4 3.5

FC + Silicone

Terpolymer7.0 6.5 90 83 2.3 3.3

FC + New

Silicone

Copolymer

6.5 6.5 83 82 3.3 3.9

65/35 Polycotton Broadcloth

FC Only 7 7 100 100 1 1.2

FC +

Aminosilicone1.5 3.5 85 80 5 5

FC +

Reactive

Silicone

Copolymer

6.5 7 100 100 4.2 3.4

FC + Silicone

Terpolymer7 7 100 100 4.3 3.1

FC + NewSilicone

Copolymer

6.5 7 100 100 3.8 2.5

Cotton Interlock Knit

FC Only 6.5 6.5 90 90 1.7 1

FC +

Aminosilicone0 0 0 0 4.1 4.8

FC +

Reactive

Silicone

Copolymer

6.5 6.0 90 80 5 4.8

FC + Silicone

Terpolymer6.5 7 90 100 3.2 3.3

FC + New

Silicone

Copolymer

6.5 7 90 100 4.4 3.0

a. Oil repellency ratings according to AATCC 118-2000 Method.

b. Spray Ratings according to AATCC 22 –2000 for twill and polycotton.Ratings for knit were using the water/IPA drop absorbency test.

c. Average rating from hand panel evaluation where 5 = Softest, 1 = Least

soft/harshest.

On cotton knit, both the silicone terpolymer and the new

copolymer had perfect performance showing no impact o

either oil repellency or water repellency as compared t

the fluorochemical treated-only fabric. Interestingly,

can be seen that higher silicone add on levels on fabri

actually improve both the oil repellency and the wate

repellency ratings. The new silicone copolymer provide

the best balance of properties as it also provides a goo

improvement on the fabric softness. The reactive silicon

shows a slight impact on both water and oil repellency a1% silicone add on levels but shows to provide the bes

softness overall. Although the aminosilicone provides

very good hand on this type of fabric as well, it shows th

highest negative impact on both oil and water repellency.

CONCLUSION

Several organo-modified silicones are available for use a

premium softeners in stain repellent and stain releas

fabric finishing. These softeners provide very goo

softness with little–to–no impact on the propertie

provided by fluorochemicals. No single silicone systemseems to provide a complete or ideal solution for all fabri

substrates or fluorochemical system. This last fact and a

well as the awareness that fabric hand preferences var

with several factors such as fiber type, fabric constructio

and even geographical region, suggest that

comprehensive evaluation of the selected organo-modifie

silicones is needed in order to identify the optimum

solution for any given fluorochemical system and/or fabri

substrate.

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REFERENCES

1. Cote, G., “New Fluorochemical Technologies for Protective Textile Finishes”, Book of papers,2002, AATCC International Conference.

2. Bender, D. “Innovations in Fabric Protection”,

2004, Textile Technology International, p.66. 3. Franchina, G., “The Chemistry and Properties

Behind Designed Fluoroprotectants for Textiles”,Book of Papers, 2001, AATCC InternationalConference.

4. Nabi, W. “New Effects in Textile Finishing withInnovative Technologies and Application of Fluorochemicals”.

5. Vazquez, F., “Trouble Free Performance inFinishing Conditions”, 2004, Textile TechnologyInternational, p.58.

6. Vazquez, F., “Silicones: Beyond Softening in

Garment Finishing”, Book of Papers, 1999,AATCC Garment Finishing Symposium.

7. Cray, S., Budden, G. Edwards, J. “AgregandoFlexibilidad al Suavizado del Tejido”, 1997,Textiles Panamericanos.

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