Wettable polymeric fabrics with durable surfactant treatment

A polymeric fabric having enhanced wettability, a method for producing such wettable polymeric fabric, and a composition for use in the method. The polymeric fabric is preferably a nonwoven. In one embodiment, the fabric includes a succinate surfactant substantially uniformly distributed on the surface of the fabric. The succinate surfactant is applied with a co-wetting aid which reduces the surface tension of the surfactant composition. In another embodiment, the polymeric fabric comprises multiple surfactants on the surface of the polymeric fabric. The first surfactant has a cloud point less than 50.degree. C. and a low solubility in water and is dispersible in water. The second surfactant comprises a succinate surfactant. The first and second surfactants are applied to the fabric in an aqueous solution preferably with a co-wetting aid such as a primary or secondary alcohol. The co-wetting aid wets the polymeric fabric with the composition during application of the composition to the polymeric fabric and then evaporates.

TECHNICAL FIELD 
This invention generally relates to polymeric fabrics, and more 
particularly, relates to surface treatments for improving the wettability 
of polymeric fabrics. 
BACKGROUND OF THE INVENTION 
Polymeric fabrics are used to make a variety of products, including 
water-absorbent articles. Such products include towels, wipes, and 
absorbent personal care products including infant care items such as 
diapers, child care items such as training pants, feminine care items such 
as sanitary napkins, and adult care items such as incontinence products. 
Polyolefin nonwoven fabrics are particularly suited for making these type 
products. 
Water-absorbent articles, especially personal care absorbent articles, 
desirably include a nonwoven polymeric fabric which provides rapid intake 
of fluid such as water or an aqueous solution, minimal spreading of fluid 
on the fabric surface before fluid penetration, and wettability which is 
durable enough to survive multiple fluid insults. However, polyolefin 
nonwoven fabrics and other types of polymeric fabrics are normally 
water-repellent. Thus, to effectively absorb water, the polymeric fabrics 
must be treated to become hydrophilic. 
One method of making polymeric fabrics more wettable is applying a 
surfactant to the surface of the fabric. Conventional surfactants for 
treating polymeric fabrics include non-ionic surfactants such as 
octylphenoxypolyethoxy ethanol. Although such conventional surface 
treatments are effective to make polymeric fabrics wettable, there are 
still some problems. For example, conventional surface treatment 
compositions such as the foregoing are relatively easily rubbed-off the 
fabric and are also easily washed-off the fabric when the fabric is 
wetted. Such surface treatments are often substantially completely removed 
from the polymeric fabric after only one liquid insult or washing. After 
the surface treatment is removed, the polymeric fabric again becomes 
water-repellent and less effective to absorb water. Moreover, to 
compensate the inability of conventional surface treatments to survive 
use, conventional surface treatments are often applied to primary fabrics 
in large quantities and thus the cost of the treated fabric is increased. 
U.S. Pat. No. 5,057,361 to Sayovitz et al. discloses a durable surface 
treatment for improving the wettability of polymeric fabrics. That patent 
discloses the treatment of polymeric fabric with a primary surfactant 
having a low solubility in water. The primary surfactant is applied to the 
fabric in an aqueous solution along with a fugitive co-surfactant or 
co-wetting aid which is functional to wet the polymeric fabric during 
application of the primary surfactant and provides for substantially 
uniform distribution of the primary surfactant onto the fabric. 
Although the surface treatment disclosed in U.S. Pat. No. 5,057,361 is an 
effective and durable surface treatment for improving the wettability of 
polymeric fabrics, there is still a need an even more durable surface 
treatment for improving the wettability of polymeric fabrics. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the present invention is to provide an improved 
polymeric fabric. 
Another object of the present invention is to provide a polymeric fabric 
having enhanced wettability. 
A further object of the present invention is to provide a polymeric fabric 
that rapidly absorbs fluid with minimal spreading of fluid on the surface 
of the fabric before the fluid penetrates into the fabric. 
Still another object of the present invention is to provide a surface 
treatment that enhances the wettability of polymeric fabrics and survives 
multiple wash cycles. 
Accordingly, the present invention provides a polymeric fabric with a 
succinate surfactant on the surface of the fabric. The present invention 
also comprehends processes for applying the succinate surfactant to the 
polymeric fabric in an aqueous solution and compositions which, when 
applied to the polymeric fabric, increase the wettability of the polymeric 
fabric. 
According to one embodiment of the present invention, a wettable polymeric 
fabric comprises a normally water repelling fabric and sorbitol succinate 
surfactant substantially uniformly distributed on the surface of the 
fabric. Suitable succinate surfactants include ethoxylated amino sorbitol 
succinate salt and alkenyl succinate anhydride ethoxylated fatty amine 
salt. The succinate surfactant is substantially uniformly distributed on 
the surface of the polymeric fabric by a process wherein the succinate 
surfactant is applied to the surface of the fabric in an aqueous 
composition comprising a co-wetting aid. The co-wetting aid reduces the 
surface tension of the aqueous composition and is present in an amount 
sufficient so that the surfactant is uniformly distributed on the surface 
of the polymeric fabric during application of the aqueous composition to 
the surface of the polymeric fabric. 
More particularly, the co-wetting aid has a surface tension within the 
range from about 20 to about 30 dynes/cm and the aqueous composition has a 
surface tension within the range from about 25 to about 50 dynes/cm. 
Suitable wetting aids include silicone polyethers and primary and 
secondary alcohols having 1 to 8 carbon atoms. 
Alternatively, instead of adding the co-wetting aid to the aqueous 
composition containing the succinate surfactant, the co-wetting aid can be 
added to the polymer from which the strands of the polymeric fabric are 
made. In this embodiment, the co-wetting aid is dispersed in the fabric 
polymer and surface segregates to the surface of the strands and thus the 
surface of the fabric. The co-wetting aid reduces the apparent surface 
free energy of the fabric and is present on the fabric surface in an 
amount sufficient so that the succinate surfactant is uniformly 
distributed on the surface of the fabric. In this embodiment, suitable 
co-wetting aids include silicone polyethers but not primary and secondary 
alcohols having 1 to 8 carbon atoms. 
According to another embodiment of the present invention, a polymeric 
fabric having enhanced wettability comprises a normally water repelling 
polymeric fabric having a surface, a first surfactant on the surface of 
the fabric having a cloud point less than about 50.degree. C. and a low 
solubility in water and being dispersible in water, and a second 
surfactant on the surface of the fabric comprising a sorbitol succinate 
surfactant. Although the foregoing first and second surfactants are 
effective when used alone to enhance the wettability of polymeric fabric, 
the combination of the first and second surfactants is a more durable 
treatment. In other words, the fabric treated with both the first and 
second surfactants in accordance with the present invention remains 
wettable after more washings than fabric treated with either the first or 
second surfactant alone. 
The first and second surfactants can be applied with a composition 
comprising the first surfactant, the second surfactant and water. More 
particularly, this composition of the present invention may include a 
co-wetting aid functional to wet the polymeric fabric with the composition 
during application of the composition to the polymeric fabric. The 
co-wetting aid is present in the composition in an amount sufficient to 
provide for substantially uniform distribution of the surfactants onto the 
polymeric fabric. 
Suitable first surfactants have a cloud point of less than about 50.degree. 
C. and include organosilicones, polyethylene oxides, and 
polyalkylene-oxide modified castor oil. More particularly, the suitable 
first surfactants include polyalkylene-oxide modified siloxanes. 
Preferably, the first surfactant comprises polyalkylene-oxide modified 
polydimethyl-siloxane. 
As with the first embodiment, suitable succinate surfactants include 
ethoxylated amino sorbitol succinate salt and alkenyl succinate anhydride 
ethoxylated fatty amine salt. 
Suitable co-wetting aids include, but are not limited to, primary alcohols 
and secondary alcohols. Hexanol is a particularly suitable co-wetting aid. 
In a preferred embodiment, the polymeric fabric of the present invention 
includes the first surfactant in an effective amount up to about 3% by 
weight of the fabric and the second surfactant in an effective amount up 
to about 3% by weight of the fabric. Preferably, the polymeric fabric of 
the present invention includes the first surfactant in an amount from 
about 0.1 to about 3% by weight of the fabric and the second surfactant in 
an amount from about 0.1 to about 3% by weight of the fabric. Most 
preferably, the polymeric fabric is a nonwoven polymeric fabric comprising 
polymeric strands such as fibers or filaments, or both. 
Still further objects and the broad scope of applicability of the present 
invention will become apparent to those of skill in the art from the 
details given hereinafter. However, it should be understood that the 
detailed description of the preferred embodiments of the present invention 
is only given by way of illustration because various changes and 
modifications well within the spirit and scope of the invention should 
become apparent to those of skill in the art in view of the following 
detailed description.

DETAILED DESCRIPTION OF THE DRAWINGS 
The present invention provides polymeric fabric having enhanced 
wettability, methods for producing such wettable polymeric fabric, 
compositions for use in the method, and articles made with the treated 
fabric. The polymeric fabrics of the present invention are suitable to 
make absorbent products such as towels, wipes and absorbent personal care 
products including infant care items such as diapers, child care items 
such as training pants, feminine care items such as sanitary napkins, and 
adult care items such as incontinence products. The treated fabric of the 
present invention is particularly suitable for making disposable diapers 
and is especially suitable for making the liner and surge or fluid 
handling layers of a disposable diaper. 
Types of polymeric fabrics which are particularly useful when surface 
treated according to the present invention include polyolefin nonwoven 
fabrics because such fabrics exhibit good absorbency characteristics and 
are relatively economically produced. Common polyolefin nonwoven fabrics 
include polypropylene and polyethylene spunbonded fabrics. Such fabrics 
are typically produced by processes disclosed in the following patents: 
U.S. Pat. No. 4,340,563 to Appel et al., U.S. Pat. No. 3,692,618 to 
Dorschner et al., U.S. Pat. No. 3,338,992 to Kinney, U.S. Pat. No. 
3,341,394 to Kinney, U.S. Pat. No. 3,502,538 to Levy, U.S. Pat. No. 
3,502,763 to Hartmann, U.S. Pat. No. 3,909,009 to Hartmann, U.S. Pat. No. 
3,542,615 to Dobo et al., and Canadian Patent Number 803,714 to Harmon. 
Nonwoven bicomponent polymeric fabrics are particularly useful when 
surface treated according to the present invention. Nonwoven bicomponent 
fabrics are typically produced by processes such as are disclosed in U.S. 
Pat. No. 3,423,266 to Davies et al. and U.S. Pat. No. 3,595,731 to Davies, 
et al. These polymeric nonwovens show substantially improved wettability 
when treated in accordance with the present invention as described below. 
The wettability of a normally water repelling polymeric fabric is enhanced 
according to the present invention by the application of succinate 
surfactant to the surface of the polymeric fabric. The surface of the 
fabric is actually formed by the surfaces of the polymeric strands from 
which the fabric is composed. Thus, the surfactant is applied to the 
surfaces of those strands which form the fabric surface. The term strands 
is meant to encompass fibers, which are cut or discontinuous strands 
having a definite length, and filaments, which are continuous strands of 
material. 
More particularly, according to one embodiment of the present invention, 
the succinate surfactant is applied to the surface of the fabric in an 
aqueous composition which includes a co-wetting aid. The co-wetting aid 
reduces the surface tension of the aqueous composition containing the 
succinate surfactant and is present in the composition in an amount so 
that the succinate surfactant can be uniformly distributed on the surface 
of the polymeric fabric. Preferably, the co-wetting aid is present in the 
aqueous composition in an amount of at least about 0.02% by weight of the 
composition to achieve substantially uniform distribution of the succinate 
surfactant on the surface of the polymeric fabric. The succinate 
surfactant is present in the aqueous composition in an amount effective to 
enhance the wettability of the polymeric fabric. Likewise, the succinate 
surfactant is present on the surface of the treated polymeric fabric in an 
amount effective to render the fabric wettable. The succinate surfactant 
is preferably present in an amount up to about 3.0% by weight of the 
fabric and more preferably in an amount from about 0.1 to about 3.0% by 
weight of the fabric. 
Suitable succinate surfactants include ethoxylated amino succinate salts 
and alkenyl succinate anhydride ethoxylated fatty amine salts. Preferably, 
the succinate surfactant has the following chemical formula: 
##STR1## 
wherein EO is ethylene oxide. 
Suitable co-wetting aids have a surface tension which is less than the 
apparent surface free energy of the polymeric fabric. For example, 
untreated polypropylene fabric typically has an apparent surface tree 
energy of about 36 dynes/cm. For application to most polymeric fabrics, 
the co-wetting aid is added to the composition in an amount sufficient to 
lower the surface tension of the composition to within the range from 
about 25 to about 50 dynes/cm. 
Suitable silicone polyethers for use as co-wetting aids include three basic 
types A, B, and C whose chemical formulas are shown below. 
Type A silicone polymers have the formula: 
##STR2## 
wherein R.sub.24 is a hydrogen or an alkyl group such as a methyl or 
n-butyl group, y is a number from about 3 to about 16, z is a number from 
about 3 to about 60. A commercially available silicone polyether of type A 
is PS-071 available from Union Carbide Corporation of Danbury, Conn. 
Type B silicone polymers have the formula: 
##STR3## 
wherein, R.sub.24 is a hydrogen atom or an alkyl group such as methyl or 
n-butyl, i is a number from about 0 to about 43, j is a number from about 
1 to 5, y is a number from about 3 to 22, and z is a number from about 0 
to 23. A commercially available silicone polyether of type B is Y-12230 
polyalkylene oxide modified polydimethyl siloxane available from Union 
Carbide Corporation of Danbury, Conn. 
Type C silicone polyether has the formula: 
##STR4## 
wherein, R.sub.21 and R.sub.24 are hydrogen atoms or an alkyl group such 
as methyl or n-butyl. Information on the range of values for g, y, and z 
was not available. A suitable silicone polyether of type C includes L-720 
silicone polyether available from Union Carbide Corporation of Danbury, 
Conn. 
Suitable alcohols for use as a co-wetting aid for sorbitol succinate 
surfactants include primary and secondary alcohols. A particularly 
suitable alcohol is hexanol. 
The wettability of polymeric fabric is enhanced according to another 
embodiment of the present invention by applying multiple surfactants to 
the surface of the polymeric fabric. The combination of surfactants is a 
more durable treatment than either of the surfactants used alone. 
Generally described, the wettable polymeric fabric of the present 
invention is surface treated with a first surfactant that has a cloud 
point less than about 50.degree. C. and a low solubility in water and is 
dispersible in water and a second surfactant comprising a sorbitol 
succinate surfactant. The cloud point is the temperature at which aqueous 
solutions of the surfactant become cloudy when cooled at a specific rate. 
The cloud point data provided herein was measured using a 1% solution of 
the surfactant in water. 
Suitable first surfactants include organosilicones, polyethylene oxides, 
and polyalkylene-oxide modified castor oil. Preferred organosilicones 
include polyalkylene-oxide modified siloxanes. Polyalkylene-oxide modified 
castor oil is a castor oil having one or more polyalkylene-oxide groups 
attached to the main carbon chain of the castor oil. Likewise, 
polyalkylene-oxide modified siloxanes are siloxanes having 
polyalkylene-oxide groups attached to the main carbon chain of the 
siloxanes. These polyalkylene-oxide modifications are well know to those 
skilled in the art. A particularly preferred first surfactant is Y-12230 
polyalkylene-oxide modified polydimethyl siloxane available from Union 
Carbide. Another suitable first surfactant is Mapeg CO-8 ethoxylated ester 
of castor oil from PPG of Gurnee, Ill. 
Suitable second (succinate) surfactants, as with the previously described 
embodiment, include ethoxylated amino sorbitol succinate salts and alkenyl 
succinate anhydride ethoxylated fatty amine salts preferably having the 
chemical formula shown above. 
The first and second surfactants are applied to polymeric fabric as a 
composition comprising the first surfactant, the second surfactant, and 
water. According to a preferred embodiment of the present invention, the 
first and second surfactants are applied to polymeric fabric as an aqueous 
composition including a co-wetting aid which is functional to wet the 
polymeric fabric with the composition during application of the 
composition to the polymeric fabric. The co-wetting aid is preferably 
present in the composition in an amount sufficient to provide for 
substantially uniform distribution of the first and second surfactants 
onto the polymeric fabric. Particularly suitable co-wetting aids include 
primary and secondary alcohols. Most primary and secondary alcohols and 
water azeotrope and evaporate relatively easily during the drying process 
so that the primary and secondary alcohols are substantially and 
completely evaporated from the treated polymeric fabric during drying. The 
surface treatment composition of the present invention preferably includes 
the co-wetting aid in an amount from about 0.05 to about 0.6% by weight of 
the composition. A particularly preferred co-wetting aid is hexanol. The 
first and second surfactants can be applied simultaneously in the same 
aqueous solution or can be applied separately, one after the other. 
The wettable polymeric fabric of the present invention preferably comprises 
the first surfactant in an effective amount up to about 3% by weight of 
the wettable polymeric fabric and the second surfactant in an effective 
amount up to about 3.0% by weight of the wettable polymeric fabric. More 
preferably, the wettable polymeric fabric of the present invention 
comprises the first surfactant in an amount from about 0.1 to about 3% by 
weight of the wettable polymeric fabric and the second surfactant in an 
amount of from 0.1 to about 3.0% by weight of the wettable polymeric 
fabric. 
Surface treatment processes within the scope of the present invention 
include printing and spraying methods and also a method whereby the 
co-wetting aid, or, in the second embodiment described above, the first 
surfactant (having a cloud point less than 50.degree. C.), is internally 
incorporated into the fabric polymers which form the polymeric strands of 
the fabric and then surface segregates through the polymer to the surfaces 
of the strands and thus the fabric surface. In the latter method, the 
succinate surfactant is applied by printing or spraying or the like. 
Suitable printing and spraying methods include those disclosed in U.S. 
Pat. No. 5,057,361, the disclosure of which is incorporated herein by 
reference. A suitable brush spray application is disclosed in a U.S. 
patent application filed on Oct. 30, 1992 and entitled "Method Of Applying 
A Coating At High Bath Concentration And Low Wet Pick-Up To Materials Such 
As Nonwovens Using A Brush Spray Applicator." The brush spray applicator 
is described in detail below with reference to FIG. 1 and FIG. 2. However, 
it should be understood that the practice of the present invention is not 
limited to the above-described methods. 
A brush spray applicator 100 used in the brush spray application method of 
the present invention is shown in FIGS. 1 and 2 and generally comprises a 
pick-up roll 103 disposed in a bath container 106 and a bristle roll 109 
positioned juxtapositional to the pick-up roll. 
The bath container 106 has an elongated trough shape and is open at the 
top. A weir 112 extends along the length the bath container 106 proximate 
the rearward side 113 of the container. The weir 112 is spaced slightly 
from the rearward side 113 of the bath container 106 and controls the 
height of the bath in the bath container. A fluid outlet 115 extends from 
the bottom of the bath container 106 between the weir 112 and the rearward 
side 113 of the container and a fluid inlet 116 extends from the bottom of 
the bath container between the weir 112 and the forward side 117 of the 
bath container. The level of the bath in the bath container 106 is kept 
constant by recirculating the bath in the container. Fluid enters the bath 
container through the fluid inlet 116, flows over the weir 112, and exits 
the bath container through the fluid outlet 115. The fluid inlet 116 and 
outlet 115 may be connected to a fluid source such as a storage tank (not 
shown). 
The pick-up roll 103 and bristle roll 109 extend between L-shaped support 
panels 118 and 121 which fit against interior sidewalls of the bath 
container 106. One of the support panels 118 is shown in phantom so that 
the pick-up roll 103 and bristle roll 109 are visible. The support panels 
118 and 121 extend below the upper edge of the weir 112 and above the 
bristle roll 109. The support panels 118 and 121 each have frontal 
portions 124 and 127 which extend inwardly along the forward side 117 of 
the bath container 106. The pick-up roll 103 and bristle roll 109 are 
rotatably mounted in hubs (not shown) in the support panels 117 and 118. 
In addition to supporting the pick-up roll 103 and bristle roll 109, the 
support panels 118 and 121 function as a spray shield to prevent fluid 
spray from escaping from the ends of the brush spray applicator 100. The 
support panels 118 and 121 also inhibit air circulation about the pick-up 
roll 103 and bristle roll 109. 
The pick-up roll 103 is positioned to extend partially above the bath 
container 106 and is partially submerged in the bath in the bath 
container. The pick-up roll 103 preferably has a shot-peened outer surface 
130 for improved liquid pick-up and is crowned to allow for deflection of 
the pick-up roll and bristle roll 109 along their lengths. 
The bristle roll 109 includes a core 133 which extends between the support 
panels 118 and 121 and an array of bristles 136 extending from the core. 
The bristles 136 are preferably from 1.2 to 1.75 inches (3.0-4.4 cm) long. 
The bristle roll 109 is positionable so that the ends of the bristles 136 
contact the outer surface 130 of the pick-up roll 103 as the bristle roll 
rotates. Preferably the bristle roll 109 is adjustable so that the length 
of the portion of the bristles 136 contacting the outer surface 130 of the 
pick-up roll 103 is variable. It is also desirable that the bristle roll 
109 be adjustable so that the bristle roll 109 can be disengaged from the 
pick-up roll 103. The dimensions of the bristles 136 and the materials 
from which the materials are made may vary, but the bristles should be 
capable of deflecting when contacting the pick-up roll 103 and then have 
enough resilience to spring to the original shape of the bristles and 
project fluid from the surface of the pick-up roll to form a spray of 
atomized fluid droplets. 
The degree of interference between the bristles 136 and the outer surface 
130 of the pick-up roll 103 is the length of the bristles which extends 
from the end of the bristles towards the core 133 of the bristle roll 109 
and contacts the outer surface of the pick-up roll as the bristles pass 
over the outer surface of the bristle roll. The degree of interference 
between the bristles 136 of the bristle roll 109 and the pick-up roll 103 
preferably ranges from about 0.01 to about 0.03 inches (0.025-0.076 cm). 
The strip of contact along the outer surface 130 of the pick-up roll 103 
between the outer surface and the bristles 136 of the bristle roll 109 
also may vary but is preferably about 1/2 inch wide. 
A spray shield 139 extends between the support panels 118 and 121 and over 
the bristle roll 109. A rearward shield 142 extends from the rearward edge 
of the spray shield 139 into the bath container 106 to a level below the 
upper edge of the weir 112 so that the lower edge of the rearward shield 
is below the level of the bath in the bath container. The rearward shield 
142 also extends between the support panels 118 and 121. An air stripping 
doctor 145 extends along the rearward side of the pick-up roll 103 and is 
connected to the rearward shield 142 by air baffles 148. The air stripping 
doctor 145, air baffles 148 and rearward shield 142 inhibit the 
circulation of air about the pick-up roll 103 and bristle roll 109. 
An upper fluid stripping doctor 151 extends from the forward edge of the 
spray shield 139 towards the nip between the pick-up roll 103 and bristle 
roll 109. A series of lower fluid stripping doctors 154, 155 and 156 are 
mounted on a platform 159 extending from proximate the nip between the 
pick-up roll 103 and the bristle roll 109 over and beyond the forward side 
117 of the bath container 106. The lower fluid stripping doctors 154, 155 
and 156 are V-shaped and extend between the frontal portions 124 and 127 
of the support panels 118 and 121. The lower fluid stripping doctor 
platform 159 has a vertical leg which extends from proximate the nip 
between the pick-up roll 103 and bristle roll 109 into the bath container 
106 to a lower edge below the upper edge of the weir 112 so that the 
platform 159 extends into the bath in the bath container. The upper fluid 
stripping doctor 151 and the lower fluid stripping doctors 154, 155, and 
156 control the path and angle of the fluid spray emitted from the nip 
between the pick-up roll 103 and bristle roll 109 and also aid in 
inhibiting the circulation of air about the pick-up roll and bristle roll. 
The upper fluid stripping doctor 151 and the lower fluid stripping doctors 
154, 155 and 156 may be set in various positions but preferably are 
positioned so that the coating solution spray emitted from the nip between 
the pick-up roll 103 and bristle roll 109 has a spray angle from about 
10.degree. to about 20.degree. and most preferably 15.degree.. As shown in 
FIG. 2, during operation of the brush spray applicator 100, the material 
to be treated, such as a nonwoven web 165, is passed over rollers 168 and 
171 and through the path of fluid spray emitted from the brush spray 
applicator. 
During operation of the brush spray applicator 100, a coating solution is 
introduced into the bath container 106 through the fluid inlet 116 and as 
explained above is continuously recirculated so that the weir 112 
maintains the bath at a constant level. The pick-up roll 103 and bristle 
roll 109 are rotated at different speeds by a motor which is not shown. 
The speeds of the pick-up roll 103 and bristle roll 109 may vary 
considerably depending on the factors such as the bath viscosity, the 
nature of the bristles 136 of the bristle roll 109, and the desired rate 
of application of the coating solution. However, the pick-up roll 103 is 
preferably operated at a speed from about 1.5 to about 15 rpm and the 
bristle roll is preferably rotated at a speed from about 480 to about 1200 
rpm. Preferably, the bristle roll is capable of operating at a velocity 
sufficient so that the coating solution can penetrate the material being 
treated, and more preferably, penetrates the material from the one side of 
the material facing the spray to the opposite side of the material. The 
line speed of the material being treated can also vary considerably but 
preferably varies between 135 and 1750 feet per minute (41-533 meters per 
minute). 
The nonwoven material 165 is preferably a hydrophobic, nonwoven spunbonded 
web having a basis weight from about 0.5 to about 1.5 ounces per square 
yard (16.8-50.4 grams per square meter) and higher. Such material is well 
known in the art and may be prepared in a conventional fashion in 
accordance with the patents identified above. 
As mentioned above, the co-wetting aid or the first surfactant (having a 
cloud point less than 50.degree. C.) can be internally incorporated into 
the polymer from which the polymeric strands forming the fabric are made. 
The co-wetting aid or first surfactant must be one that surface segregates 
from inside the polymeric strands to the outer surfaces of the strands and 
thus the surface of the fabric. One such material is trisiloxane polyether 
having the following formula: 
##STR5## 
wherein EO is ethylene oxide. 
Methods for internal incorporation of co-wetting aids and surfactants into 
the polymer from which a polymeric fabric is made are disclosed in U.S. 
Pat. Nos. 4,857,251; 5,057,262; 5,114,646; and 5,120,888, the disclosures 
of which are expressly incorporated herein by reference. 
The following Examples 1-10 are designed to illustrate particular 
embodiments of the present invention and teach one of ordinary skill in 
the art how to carry out the present invention. The following Comparative 
Examples 1-6 are designed to illustrate advantages of the present 
invention. 
EXAMPLE 1 
The ability of aqueous compositions comprising succinate surfactant to 
wet-out on nonwoven polypropylene fabric was evaluated by adding gradually 
increasing amounts of silicone polyether to aqueous compositions 
comprising succinate surfactant and then applying the composition to the 
surface of the fabric. The succinate surfactant (SS) was alkenyl succinate 
anhydride ethoxylated fatty amine salt having the following formula: 
##STR6## 
wherein EO is ethylene oxide. 
The silicone polyether was PS-071 silicone polyether available from Huls of 
Piscataway, N.J. The contents of the aqueous compositions are shown in 
Table 1 along with the surface tension of the compositions and an 
indication of the ability of the compositions to wet the fabric. The 
ability of the compositions to wet the fabric was obtained from a visual 
observation. The surface tensions were measured using a Tensiometer 
available from Fisher Scientific. The apparent surface free energy of the 
polypropylene fabric was about 36 dynes/cm. The ability of the 
compositions to wet the fabric is indicated as poor or good. From the 
results in Table 1, it can be seen that the minimum concentration of 
silicone polyether to achieve good wet-out on polypropylene fabric is 
between 14.5 and 29 mg per 100 ml or about 0.02% by weight. 
TABLE 1 
______________________________________ 
Sample 1 2 3 4 5 6 
______________________________________ 
water (ml) 
100 100 100 100 100 100 
SS (% weight) 
0.5 2 2 2 2 2 
PS-071 (mg) 
0 0 14.5 29 43.5 58 
surface tension 
33 33 32 30 29 28-29 
(dynes/cm) 
wet-out poor poor poor good good good 
______________________________________ 
EXAMPLE 2 
A 0.7 osy (24 gsm) polypropylene spunbond fabric was treated with a 
surfactant bath using a nozzle spray apparatus as disclosed in U.S. Pat. 
No. 5,057,311. The treatment bath comprised 2% by weight alkenyl succinate 
anhydride ethoxylated fatty amine salt and 0.03% by weight silicone 
polyether, with the remainder being water. The alkenyl succinate anhydride 
ethoxylated fatty amine salt had the chemical formula shown in Example 1 
and the silicone polyether had the following chemical formula: 
##STR7## 
wherein EO is ethylene oxide. The fabric was dried and the dry add-on 
weight as a result of the treatment was 0.94-0.96% by weight of the 
fabric. The resulting treated fabric was subjected to a water run-off test 
to evaluate the durability of the surfactant treatment. The run-off test 
was performed with the following procedure: 
A 6 inch by 6 inch (15.times.15 cm) piece of treated fabric was placed flat 
on top of an absorbent medium which was positioned at a 30.degree. incline 
plane. A funnel was placed above the fabric. 100 milliliters of distilled 
water at about 35.degree. C. was dispensed from the funnel onto the fabric 
over a time period of about 15 seconds. Any of the distilled water that 
was not absorbed by the fabric ran off the fabric and was collected. The 
volume of run-off was measured. The samples of the fabric were repeatedly 
subjected to the run-off test and then washed until the amount of run-off 
water from the run-off test exceeded 20 milliliters. 6 wash cycles were 
required for the run-off test to exceed 20 milliliters. The fabric samples 
were washed by stirring the fabric in 1000 ml of tap water for 3 hours. 
EXAMPLE 3 
Three samples A, B, and C, of 0.8 osy (27 gsm) spunbond polypropylene 
fabric were treated with surfactant compositions by dipping the samples in 
the compositions. Sample A was treated with an aqueous composition 
comprising Triton X-102 surfactant available from Rohm and Haas and the 
resulting dry add-on weight of the surfactant was 0.7% by weight of the 
fabric. Sample B was treated with an aqueous composition comprising 
trisiloxane polyether and the resulting dry add-on weight of the 
surfactant was 1% by weight of the fabric. Sample C contained 1.0% by 
weight trisiloxane polyether present on the polypropylene fabric fiber 
surface through surface segregation and was treated with an aqueous 
composition comprising alkenyl succinate anhydride ethoxylated fatty amine 
salt having the same chemical formula as shown in Example 1. The dry 
add-on of the alkenyl succinate anhydride ethoxylated fatty amine salt was 
0.7% by weight of the fabric. The three samples were repeatedly subjected 
to 60 ml water insults and with each insult the time for penetration of 
the water was measured. The results are graphically shown in FIG. 3. As 
can be seen, sample C treated with trisiloxane polyether and succinate 
surfactant remained wettable for significantly more insults than samples A 
and B. 
EXAMPLE 4 
A through-air bonded polypropylene/polyethylene bicomponent spunbond 
nonwoven fabric having a basis weight of 1.5 osy (50 gsm), a thickness of 
0.05 inches (0.13 cm), and filaments of 4 denier was treated with the 
brush spray applicator system 100 described above and shown in FIGS. 1 and 
2. The treatment bath comprised multiple surfactants, 10% by weight of a 
first surfactant, Y-12230 polyalkylene-oxide dimethyl siloxane available 
from Union Carbide, 25% by weight of a second surfactant, the alkenyl 
succinate anhydride ethoxylated fatty amine salt having the formula shown 
in Example 1, and 65% by weight water. The fabric was treated at a line 
speed of 135 feet per minute (41 meters per minute) and was through-air 
dried at a temperature of 240.degree. F. (115.degree. C.). 
The pick-up roll 103 was made of stainless steel with a 100 rms finish and 
had a 6.375 inch (16.2 cm) diameter. The pick-up roll 103 was rotated at 
3.2 rpm. The brush roll 109 had a total diameter of 107/16 inches (26.5 
cm) and white nylon bristles that were 13/8 inches (3.5 cm) long with a 
diameter of 0.012 inches (0.030 cm). The bristle roll 109 was rotated at 
850 rpm. The degree of interference between the bristles 136 of the 
bristle roll 109 and the outer surface 130 of the pick-up roll 103 was 
0.015 inches (0.038 cm) and the clearance between the bristle roll and the 
spray shield 139 was 1/16 inch (0.16 cm). The clearance between the upper 
fluid stripping doctor 151 and the bristle roll was 1/16 inch (0.16 cm) at 
the heel and 0.015 inches (0.038 cm) at the tip. The lower fluid stripping 
doctors 154, 155, and 156 were located 1/8 inch (0.32 cm) below the top of 
the pick-up roll 103. The air baffles 148 were spaced 6 inches (15 cm) 
apart and the clearance between the air baffles and the bristle roll was 
1/32 inch (0.08 cm). The bath in the bath container 106 was recirculated 
between the bath container and a recirculation tank at a rate of 5 gallons 
per minute (19 liters per minute). The level of the bath was maintained 
such that the pick-up roll 103 was submerged 2.25 inches into the bath. 
The strip of contact between the outer surface 130 of the pick-up roll 103 
and the bristles 136 of the bristle roll 109 was about 1/2 inch (1.3 cm) 
wide. The resulting spray from the bristle roll 109 was controlled to a 15 
degree pattern by the upper fluid stripping doctor 151 and the lower fluid 
stripping doctors 154, 155 and 156. The nonwoven web was directed 
vertically and upwardly with respect to the brush spray applicator system 
100 at a distance of 1/4 inches (0.64 cm) from the outermost portion of 
the lower fluid stripping doctor platform 159 and 81/4 inches (21 cm) from 
the nip between the pick-up roll 103 and the bristle roll 109. 
EXAMPLE 5 
A through-air bonded 50/50 side by side polypropylene/polyethylene 
bicomponent spunbond nonwoven fabric having a basis weight of 1.5 osy (50 
gsm) and filaments of 4 denier was treated with a surfactant bath using a 
nozzle spray apparatus as disclosed in U.S. Pat. No. 5,057,361. A 
treatment bath comprising 0.53% by weight of a first surfactant, Y-12230 
polyalkylene-oxide dimethyl siloxane available from Union Carbide, 1.33% 
by weight of a second surfactant, the alkenyl succinate anhydride 
ethoxylated fatty amine salt having the formula shown in Example 1, with 
the remainder being water. The fabric was treated at a line speed of 80 
feet per minute (24 meters per minute) and was through-air dried at a 
temperature of 250.degree. F. (121.degree. C.). 
Samples of the treated fabrics from Examples 4 and 5 were evaluated and 
results are shown in Table 2. The wet pick-up is shown in percent by 
weight of the web fabric and is the amount of bath added to the fabric 
before drying. The surfactant dry add-on is the amount of surfactant added 
to the dried treated fabric in percent by weight of the dry treated 
fabric. The run-off test was performed with the following procedure: 
A 5 inch by 15 inch (13.times.38 cm) piece of a treated fabric was placed 
flat on top of an absorbent medium which was positioned at a 30.degree. 
incline plane. A funnel was placed above the fabric. 100 millimeters of 
distilled water at about 35.degree. C. was dispensed from the funnel onto 
the fabric over a time period of about 15 seconds. Any of the distilled 
water that was not absorbed by the fabric ran off the fabric and was 
collected. The volume of run-off water was measured. 
The samples of fabric were repeatedly subjected to the run-off test and 
then washed until the amount of run-off water from the run-off test 
exceeded 20 milliliters. The number of cycles required for the run-off 
test to exceed 20 milliliters is shown in Table 2. The fabric samples were 
washed by submerging the samples in 500 milliliters of water at 25.degree. 
C. and than agitating the samples in the water for 1 minute. The washed 
samples were then dried in a oven at 200.degree. F. (93.degree. C.) for 8 
minutes. 
TABLE 2 
______________________________________ 
Example 4 
Example 5 
______________________________________ 
Basis Weight (osy) 
1.5 1.5 
Basis Weight (gsm) 
50 50 
First Surfactant 0.4 0.4 
Dry Add-On, % 
Second Surfactant 
1.0 1.0 
Dry Add-On, % 
Wet PickUp % 4.0 75 
Wash/Runoff Cycles 
6 7 
______________________________________ 
As can be seen from the data shown in Table 2, the fabric sample from 
Example 4 treated in accordance with the present invention remained 
hydrophilic for up to 6 wash cycles and had a wet pick-up of only 4% by 
weight. The fabric sample from Example 5 wherein the surfactant was 
applied with a nozzle spray remained hydrophilic for up to 7 wash cycles 
but had a wet pick-up of 75% by weight after treatment. The line speed for 
Example 4 was considerably faster than of Example 5 because the drying 
time for the sample from Example 4 was significantly less than that for 
compared to Example 5 due to the low wet pick-up of the fabric from 
Example 4. 
EXAMPLE 6 
A through-air bonded 50/50 side by side polypropylene/polyethylene 
bicomponent spunbond nonwoven fabric having a basis weight of 1.5 osy (50 
gsm) and filaments of 4 denier was treated with successive surfactant 
baths using a nozzle spray apparatus as disclosed in U.S. Pat. No. 
5,057,361. A first treatment bath comprising 1.33% by weight alkenyl 
succinate anhydride ethoxylated fatty amine salt having the formula shown 
in Example 1, with the remainder being water, was applied to the surface 
of the fabric at a line speed of 80 feet per minute (24 meters per 
minute). A second treatment bath comprising 0.53% by weight Y-12230 
polyalkylene-oxide dimethyl siloxane available from Union Carbide, and 
0.3% by weight hexanol, with the remainder being water, was then applied 
to the surface of the fabric at the same line speed. The treated fabric 
was through-air dried at a temperature of 250.degree. F. (121.degree. C.). 
EXAMPLE 7 
Example 6 was repeated except that the order of application of the first 
and second baths was reversed. 
EXAMPLE 8 
Example 6 was repeated except that the fabric being treated comprised 
homofilaments of polypropylene instead of bicomponent filaments. 
EXAMPLE 9 
Example 6 was repeated except that the second treatment bath comprised 
0.53% by weight Mapeg CO-8 ethoxylated ester of castor oil from PPG of 
Gurnee, Ill., instead of Y-12230. 
EXAMPLE 10 
Example 9 was repeated except that the order of application of the first 
and second treatment baths was reversed. 
COMATIVE EXAMPLE 1 
A through-air bonded 50/50 side by side polypropylene/polyethylene 
bicomponent spunbond nonwoven fabric having a basis weight of 1.5 osy (50 
gsm) and filaments of 4 denier was treated with a single surfactant bath 
using a nozzle spray apparatus as disclosed in U.S. Pat. No. 5,057,361. 
The treatment bath comprised 1.33% by weight alkenyl succinate anhydride 
ethoxylated fatty amine salt having the formula shown in Example 1, with 
the remainder being water, and was applied to the surface of the fabric at 
a line speed of 80 feet per minute (24 meters per minute). The treated 
fabric was through-air dried at a temperature of 250.degree. F. 
(121.degree. C.). 
COMATIVE EXAMPLE 2 
Comparative Example 1 was repeated except that the treatment bath comprised 
0.53% by weight Y-12230 polyalkylene-oxide dimethyl siloxane available 
from Union Carbide and 0.3% by weight hexanol, with the remainder being 
water. 
COMATIVE EXAMPLE 3 
Comparative Example 1 was repeated except that the treatment bath comprised 
0.53% by weight Mapeg CO-8 ethoxylated ester of castor oil available from 
PPG, of Gurnee, Ill., with the remainder being water. 
COMATIVE EXAMPLE 4 
Comparative Example 1 was repeated except that the treatment comprised 
1.87% by weight alkenyl succinate anhydride ethoxylated fatty amine salt 
having the formula shown in Example 1, with the remainder being water. 
COMATIVE EXAMPLE 5 
Comparative Example 1 was repeated except that the treatment comprised 
1.87% by weight Y-12230 and 0.3% by weight hexanol, with the remainder 
being water. 
COMATIVE EXAMPLE 6 
Comparative Example 1 was repeated except that the treatment comprised 
1.87% by weight Mapeg CO-8, with the remainder being water. 
Samples of the treated fabrics from Examples 6-10 and Comparative Examples 
1-6 were evaluated and results are shown in Table 3. The amounts of the 
surfactants in the baths are shown in percent weight and the succinate 
surfactant is identified as "SS". The dry add-on is the amount of 
surfactant added to the dried treated fabric in percent by weight of the 
dry treated fabric. The run-off test was performed with the same procedure 
described above with regard to Examples 4-10 and the results are shown in 
number of wash cycles survived. 
TABLE 3 
__________________________________________________________________________ 
First Surfactant Bath Second Surfactant Bath 
DRY DRY 
SURFACT- 
BATH ADD- 
SURFACT- 
BATH ADD- 
WASH 
EXAMPLE FANT CONCENTRATION % 
ON % 
ANT CONCENTRATION % 
ON 
CYCLES 
__________________________________________________________________________ 
6 SS 1.33 1.0 Y-12230 
0.53 0.4 9 
7 Y-12230 
0.53 0.4 SS 1.33 1.0 6 
8 SS 1.33 1.0 Y-12230 
0.53 0.4 10 
9 SSS 1.33 1.0 MAPEG 0.53 0.4 9 
10 MAPEG 0.53 1.0 SS 1.33 1.0 7 
COMATIVE 1 
SS 1.33 1.0 -- -- -- 2 
COMATIVE 2 
Y-12230 
0.53 0.4 -- -- -- 3 
COMATIVE 3 
MAPEG 0.53 0.4 -- -- -- 4 
COMATIVE 4 
SSS 1.87 1.4 -- -- -- 3 
COMATIVE 5 
Y-12230 
1.87 1.4 -- -- -- 3 
COMATIVE 6 
MAPEG 1.87 1.4 -- -- -- 5 
__________________________________________________________________________ 
As can be seen from the data in Table 3, the multiple surfactant treatments 
used in Examples 6-10 were more durable than the single surfactant 
treatments of Comparative Examples 1-6. This was true even for Comparative 
Examples 4-6 wherein the single surfactant treatments were applied to 
provide a surface concentration equal to the total surfactant surface 
concentration applied by the multiple surfactant treatments of Examples 
6-10. 
The foregoing descriptions relates to preferred embodiments of the present 
invention, and modifications or alterations may be made without the 
departing from the spirit and scope of the invention as defined in the 
following claims.