Note: Descriptions are shown in the official language in which they were submitted.
~ 3~8088
This invention relates to a method for modifying the
~urface of a synthetic fibrou~ sheet material by applying to
the surface of the ~heet material a coating composition that
accepts marking with pencil, ink pen, and printing equipment.
Sheet materials manufactured from fibers of synthetic
polymers, ~uch as polyethylene and polypropylene fiber, are
frequently used to replace paper in reusable mailing envelopes
and similar stationary articles that require a high degree of
resistance to wear. However, such wear-resistant paper re-
10 placements ha~ been limited by the fact that such synthetic -~
papers are not receptive to being written on with lead pencil~
or ink pen~ or printed on with conventional printing media,
apparently becau~e the~r ~urfaces tend to be slippery and
hydrophobic and lack any chemical functionality that would
tend to lnteract with inks and dyes used in writing and print-
ing.
One attempt to deal with that problem is disclo~ed in
U.S. Pat~nt No. 4,092,457, which describes a fibrous sheet
material for improved off-~et printing, which i8 composed at
least partly of polyolefin fibers in which a hydrophilic
component such as polyvinyl alcohol has been incorporated by
polymer blending or graft polymerization before the fibera
are ~pun. The sheet material i8 treated with a water-soluble
polymer, such as polyvinyl alcohol and polyacrylamide, as well
a~ with an aqueous emul~ion of a high molecular weight polymer
such as vinyl acetate. The coating composition iY then
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22124-1707
dried by heating. Treatment of the sheet material either with a
water-soluble polymer alone or an aqueous-polymer emulsion alone
does not achieve the effect contemplated by the patent.
It would be desirable to provide a method for modifying
the surface of a synthetic fi~rous sheet material by applying to
the sheet material a water-soluble coating composition that is
curable by irradiation alone to form a water-insoluble surface
coating that is more receptive to marking with ink pen and
printing equipment.
According to the invention, a method for modifying the
surface of a synthetic fibrous sheet material by applying to its
surface à water-based coating composltion comprislng a water-
~oluble polymer, is characterlzed in that the water-soluble
polymer ls photolnsolubllizable, has a molecular welght from about
10~000 to about 4,000,000, and 18 selected from the group
con~lstlng of polysaccharides and allphatlc derlvatives of
poly~accharldes, polyvlnyl alcohol, polyacryllc acld, pectln and
polyethylene oxlde and ln that the composltlon 18 applled, drled
and cured by lrradlatlon for a tlme sufficient to form a water-
ln~oluble coatlng that accepts marklng with ink pen and prlnting
equlpment.
Another aspect of the inventlon provides a synthetlc
flbrous sheet materlal that ha been coated wlth the composition
deflned above and lrradiated, thereby rendering the surface able
to accept marking wlth lnk pen and prlntlng equlpment.
Preferably the water-soluble polymer has a molecular
welght from about 500,000 to about 2,000,000, and 1~ a hydroxy-
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22124-1707
alkylcellulose, such as hydroxyethyl or hydroxypropylcellulose, an ..
aminoethyl derivative of hydroxyethyl or hydroxypropylcellulose, a :~
hydrophobically modified hydroxyethyl or hydroxypropylcellulose, ~:
or carboxymethylcellulose. Most preferred are
hydroxypropylcellulose, hydroxypropylcellulose modified with about
from 1 percent to about 10 percent by weight aminoethyl groups, -
and hydroxypropylcellulose modified with about from O.1 percent to ~:
about 2 percent by welght of a 16 carbon alkyl chain. :
Other suitable water-soluble polysaccharides include
natural and æynthetic polymers such as Guar Gum and their
aliphatlc derivatives such as carboxymethyl and hydroxypropyl
modified Guar Gum, Agar, Gum Carrageenan, Gum Arabic, Gum
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~ 3~808~
Ghatti, Gum Karaya, Gum Tragacanth, Locust Bean Gum, Xanthan
Gum and pectin, all o~ molecular weight from about 20,000 to
about 500,000, and preferably from about 80,000 to about
400,000. Other useful water-soluble polymers are polyvinyl
alcohol, polyacrylic acid and polyethylene oxide, all of
molecular weight from about 10,000 to about 2,000,000 and
preferably from about 100,000 to about 1,000,000.
Generally, the higher the molecular weight of a given
water-soluble polymer, the shorter the duration of curing
treatment needed to effect an aqueous insoluble coating. For
example, a coating composition comprising hydroxypropylcellu-
lose of average molecular weight 1,000,000 requires only about
15 percent of the photo exposure needed for ~uch a compo~ition
employing hydroxypropylcellulose of average molecular weight
60,000. Likewise, a coating composition employing polyacrylic
acid of average molecular weight 4,000,000 provide~ acceptable
aqueous-insoluble coatings; when such a composition employing
polyacrylic acid of average molecular weight 300,000 is ir-
radiated for the same amount of time and in the same manner an
unacceptable coating is provided that is not water-insoluble.
Curing of the photoinsolubilizable coating compositions
of this invention can be conventionally performed by ultra-
violet light, electron beam or corona discharge treatment.
Exposure time can vary from about 0.5 seconds to about 5
minutes. Ths preferred exposure time can vary considerably,
depending upon such parameters as the particular water-soluble
compound employed in the photoinsolubilizable coating composi-
tion, and the molecular weight of said water-soluble compound.
Other factors include method of curing and the amount and/or
type of ultraviolet-transparent abrasive material used.
Preferably, in the method according to the invention the
coating composition also comprises an ultraviolet-transparent
abrasive material of particle size of less than about 0.05 mm
(50 microns), which improves the ability to accept marking
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~ 3~808~ 22124-1707 ~
with ink pen, as opposed to printing with dyes. Any particulate
abrasive material of the required particle size and having at
least partial ultraviolet transparency is useful in the
photoini~iolubilizable coating compositions of this invention.
Silica is the preferred abrasive material due in part to its
hardness and excellent ultraviolet transparency properties. Other
suitable abrasive materials are partlcles of glass, calcium
carbonate, aluminum hydroxide, zinc oxlde, titanium dioxide,
calclum carbonate and magneslum oxide.
The amount of water-soluble compound employed herein and
the weight percent ratio of water-soluble compound to abrasive
material can both vary depending on such parameters as the
speciflc water-soluble compounds and abrasive substances employed,
the particùlar synthetic flber-containing textile surface to be
coated and further descrlbed below, the degree of ink pen,
prlntlng or dye image receptivlty desired of the textile surface,
and the speclfic end uses contemplated of the thus coated
synthetic fiber-containing textile material.
Preferably, coatlng compositions according to the
invention comprise from about 0.1 percent to about 5 percent by
welght of the water-soluble polymer, and up to about 1 percent by
weight of the abrasive material. More preferably, the coating
compositions contain about 0.3 percent to about 2 percent by
weight of the water-soluble polymer, and about 0.05 percent to
about 0.5 percent by weight of the abrasive material.
Water is the vehicle in the photoinsolubilizable coating
compositions of this inventlon, but surfact~nts or organlc
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~ 328088
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cosolvents, for example, acetone, may be employed as coating aids
depending upon such end results contemplated as degree and
thickness of coating.
Nonwoven and woven synthetic fiber-containing sheet
materials are suitable substrates for the coating compositions
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of this invention. Preferred are spunbonded nonwoven fabrics
comprising polyethylene or polypropylene fibers, such as are
~;~ commercially available from E. I. du Pont de Nemour~ as Tyvek~
f~ and Typar brands, respectively. Other exampleq of synthetic
fiber-containing materials suitable a~ substrate~ for the
coating compo~itions of this invention include woven or
nonwoven materials made of polyolefins, and halogenated
derivative~ of polyolefins, polyester, polyacetyl, polyamide,
polyacrylate or methacrylate, and ~ilicone fibers.
The following examples more fully illustrate the pre-
ferred embodiment~ of this invention.
Example 1
This example demonstrates a preferred coating composi-
tion of this invention, and in particular, its unique photo-
sensitive properties re~ponsible for providing syntheticfiber-containing textile materials with improved pencil and
ink pen image receptivity.
A photoin~olubilizable coating composition is prepared
by dispersing 0.25 grams (0.14 weight percent) a~orphous
silica of a particle size of less than approximately 0.01 mm
(10 microns), (Illinois Minerals IMSIL A-15), in a solution
of 1.0 gram (0.56 weight percent) of hydroxypropylcellulose
modified with 5 weight percent of aminoethyl groups (Hercules'
Klucel- 6) in 139 milliliters of water and 55 milliliters
of acetone.
A coupon of spunbonded polyethylene textile material (Du
Pont's Tyvek) is then dipped in the above-described coating
composition, dried for one hour at 60C in a forced air oven
and exposed for 2 seconds to the irradiation from a microwave-
fired, high pressure mercury lamp. The coupon is then washedfor one hour in a water/acetone mixture of weight percent
ratio 76/24 to determine the resistance of the coating com-
position to dissolution, and then for pencil and ink pen
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l 328088
image receptivity.
Writing on the photo exposed side of the coupon with a
No. 2 graphite pencil and ordinary ink pen resulted in image
quality comparable to that obtained on writing on a piece of
ordinary writing paper. A ~imilarly prepared coupon, not
expo~ed to irradiation, gave after washing approximately the
same pencil and ink pen image non-receptivitiy a~ ob~erved on
an untreated coupon.
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Example~ 2 to 4
Examples 2 to 4 further illustrate preferred embodiments
of this invention.
In Example 2, 0.5 grams (0.1 weight percent) o~ IMSIL
A-15 amorphous silica is dispersed iA a solution of 2.0 grams
(0.4 weight percent) hydroxypropylcellulose (Hercules'
KlucelO H) in 500 milliliters of water.
A coupon of spunbonded polyethylene textile material i~
then coated in the above composition, photo exposed as in
Example 1, with the exception that a 5-second exposure time
i~ usod, and further wa~hed a~ ~et forth in Example 1. As in
Example 1, pencil and ink pen image receptivity of the treated
coupon are comparable to that obtained on writing on ordinary
writing paper.
In Example 3, 0.15 gram~ (0.09 weight percent) of DMSIL
A-15 amorphous silica is dispersed in a solution of 0.6 gram~
(0.36 weight percent) of hydroxyethylcellulose having 0.55
weight percent modification with a 16-carbon chain (Hercules
Incorporated WSP D-330~ in 125 milliliters of water and 51
milliliters of acetone. - -
A ~punbonded polyethylene coupon is coated and treated --
as in Example 1. As before, pencil and ink pen image recep-
tivity i~ comparable to that obtained on writing on ordinary
writing paper.
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1 328088
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In Example 4, 0.5 grams (0.3 weight percent) of IMSIL
A-15 amorphous silica i8 dispersed in a solution of 2.0 gram
(1.2 weight percent) modified hydroxypropylcellulose (contain-
ing 0.3 weight percent of appended 16-carbon chains) in 125
milliliters of water and 51 milliliter~ of acetone.
A spunbonded polyethylene coupon is then treated as in
Example 1, with the exception that a 30-second photo expocure
is employed. Pencil and ink pen image receptivity of the
thus treated coupon are comparable to that obtained on writ-
ing on ordinary writing paper.
Example 5
This example further illustrates an embodiment of theinvention wherein a corona discharge source is employed,
instead of an ultraviolet light, to produce a photoinsolubil-
izable coating composition in accordance with this invention.
0.4 pounds (0.1 weight percent) of I~SIL A-15 amorphous
silica is dispersed in a solution of 1.6 pounds (0.4 weight
percent) hydroxypropylcellulose in 400 pounds of water.
A coupon of spunbonded polyethylene textile material i9
then coated with the above composition and dried for one hour
in a 70C forced air oven, and then passed under a 200 watt
corona treater at a rate of 70 feet/minute and at a distance
of 1/16 inch from the source. The coupon i~ further washed
for one hour in a mixture 176 milliliters of water and 76
milliliters of acetone then dried for one hour at 70C as
described in the above examples. Pencil and ink pen image
receptivity of the thus treated coupon is comparable to that
obtained on writing on ordinary writing paper.
Example 6
This example further illustrates an embodiment of this
invention wherein electron beam treatment, instead of ultra-
violet light on corona discharge, is employed to produce a
1 328088
photoinsolubilizable coating compo~ition in accordance with
this invention.
A coupon of spunbonded polyethylene i~ coated with the
composition used in Example 5 and dried in a forced air oven
for one hour at 75C, and then exposed to 0.5 megarads of 0.2
MEV electrons from a commercially available electron beam
unit. The coupon is then washed in 200 milliliters of water
for one hour followed by drying for one hour at 75C in a
forced air oven. Pencil and ink pen image receptivity of the
thus treated coupon is found to be comparable to that obtained
on writing on ordinary writing paper, such as described in
the above examples.
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ExamPle ?
Thi8 example is further illustrative of an aspect of
this invention wherein photoinsolubilizable coating composi-
tion~ herein improve dye receptivity of synthetic fiber-
containing textile materials.
A treated coupon of spunbonded polyethylene i8 prepared
and photo exposed as illuatrated in Example 2 above, and is
then stirred for 70 minutes at 67-C in a dye bath con3isting
~ of 12 grams of RIT brand tint and dye dissolved in 214 milli-
:- liters of water. After removal from the bath and rinsing in
water for 30 minutes, the coupon is found to have excellent
dye retention. A control coupon that is dyed without any
previous treatment shows esYentially no dye retention after
washing as above described.
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