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Sept. 10, 1946. I
Filed March 11, 1943
é Sheets-Sheet 1
?'uz'ny Gurwick
Sept. 10, 1946.
Filed March 11, 1943
2 Sheets-Sheet 2
Irving G'ur wick
Patented Sept-10, 194s ._
Irving Gurwick, New York, N. Y.
Application Mai-en u. 194:. Serial No. mm
O'Claims. (01. 154-97)
This invention relates to the surface coating
the use of a resin which'may be used as a heat
-~of a porous paper such as tissue or ?lter paper
with a thermo-responsive resin such as vinyl co
sealing means, that is, one sealed by the applica
polymer for the making of food containers such
, tion of heat and‘pressure, the resulting union
stitched, although it is evident that they might
more conveniently and economically be cement
the foregoing desiderata are successfully at
tained. The resulting coating of the resin is 10
15 calized super?cially on the surface of the paper
being water-proof as well as heat-proof. Vari
as tea bags.
5 ous methods of applying resin to the paper have
The application or use of the method of the
been attempted, but so far as I am aware, none of
present invention for the making of tea bags is
these have been successful in meeting these re
one of the important exempli?cations of the
quirements, which are the desiderata for the
principles thereof. Tea bags were ?rst made of
making of an acceptable or successful product.
cloth, but more recently have been made of a 10
I have found that a theme-responsive, such
high grade of permeable paper of adequate wet
as a thermoplastic resin may be coated on the
strength. The edges of these paper tea bags are
surface of a tissue or ?lter paper so that all of
1 ed.
It has been attempted to apply to the sur
face of the paper a coating of a thermo-respom;
,sive, i. e., either a thermoplastic or a thermo
setting, resin for the purpose of providing a ce
mentitious sealing for the edges'of the tea bags
and for the purpose of increasing the wet
strength of the paper. \_\Such attempts, however,
despite the porous and highly absorbent nature
of the paper. This resin coating serves as the
required heat sealing medium for the edges of
the container product made from the paper.
The resin coating is applied by relatively simple
manufacturing steps whichmay be practiced so
that the integrity of the paper texture and ?bers
may be fully retained. The resulting resin ?lm
so far as I am aware, have not been successful.
There are a number of requisites for the mak
ing ofan acceptable ‘resin coated food container
or coating, while being in a fibre adherent con
which is to serve as an infusion or ?ltration prod 25 dition is, nevertheless, discontinuous so as to
uct such as a tea bag or a coffee bag. A major
form an open mesh which, therefore, at the same
difficulty arises in applying the resin to the thin
time increases the‘wet strength of the tissue pa
porous paper. The'resin, particularly when ap
per and permits or retains the desired ?ltration
plied as a resin solution, is readily absorbed into
'or infusion characteristic of the paper. The
and even through the paper, and this leads to 30 resin coating is in such a condition when applied
many diiiiculties. Impregnation of the resin so
that all of the solvent may be‘removed without
lution into and through the paper fibres results
difi‘lculty, producing an odorless or tasteless prod
in manufacturing di?iculties; the paper becomes
uct. The method of surface coating 9. tissue pa
sticky on the opposite surface and the paper
per with athermo-responsive, such as a thermo
tends to stick to the impression roller on the op 35 plastic, resin for accomplishing these results is
posite side of the coating roller, resulting in fre
_ the prime object of my present invention.
quent tearing or breakage of the tissue or ?lter
I have found that a most suitable thermo-re- '
paper, this in turn requiring the apparatus to be
sponsive resin for this purpose is a vinyl co
shut down, the various rolls to be thoroughly
polymer. In accordance with the method of the
cleaned, following which’ the paper must be 40 present invention, I ?rst coat a ?lm of a solution
threaded anew through the apparatus. Another
of a vinyl resin on a non-adherent carrier, that
major dimculty is that the coating ?lm produced
is to say, a‘ carrier of the class consisting of Cello
is too thick and is impervious or is in such a con
phane, glassine, or waxed paper. The carrier
dition that it is dimcult to render the same per
applied resin ?lm is then treated to effect par
vious, thus negativing the infusion or ?ltration 45. tial evaporation of the solvent, leaving the ?lm
characteristic desired for the product. A‘ still
partially dried and in a still tacky condition.
further dimculty is that a very long drying pro
The thus treated ?lm on the carrier is then con
tacted with the tissue or ?lter paper. The car
rier and the tissue paper are then separated, the
cedure utilizing undesirable high temperatures
must be used in an effort to drive off all of the
solvent in the resin solution, this being most dif 50 resin coating thereby transferring from'the car
?cult to do when the resin solution has soaked
'rier and becoming adheringly attached to the
into the paper. This latter di?lculty is aggra
contacted surface of the‘ tissue or ?lter paper.
vated by the need for removing all of the residu
The residual solvent is then removed from the
ary solvent to render the' product odorless and
resin coated tissue paper and the resulting prod-' -
tasteless. A further important desideratum is
not is thereby produced.
partial drying of the resin to a non-liquid. tacky
This‘5 application is a continuation in part of my
condition. Over this distance, the carrier applied
coating or ?lm is thus treated to effect partial
evaporation of the solvent leaving the ?lm par
tially dried and in a still tacky condition. (At
To the accomplishment of the foregoing ob- '
the same time, considerable of the solvent, all of
jects, and such other objects as may hereinafter
which must eventually be eliminated, is removed.)
appear, my invention consists in the porous paper
The time needed depends on the rate of evapora
containers and the process for making the same, tion of the solvent, which in turn is affected by
- and their relation one to the other,‘ as hereinafter
are 'more particularly described in the speci?ca 10 the weather. If desired, temperature and humid
ity control may be used to insure uniform drying
tion and sought to be de?ned in the claims. The
application Serial No. 445,414, ?led June 2, 1942, .
for “Coating of porous material for container or
the like." now abandoned.
time, or extra arti?cial drying means may be em
speci?cation is accompanied by drawings in
' pioyed, ranging from the simple use of an electric
fan, to more elaborate drying means including
Fig. 1 illustrates a paper blank for a tea bag;
Fig. 2 shows the same folded and sealed;
Fig. 3 illustrates the ?lled and completed tea
heaters. For all ordinary purposes the latter are
not necessary, because the coating is thin, and
the acetone solvent is volatile and dries rapidly.
The tissue or ?lter paper is also in the form
of a moving web. The web 22 of tissue paper is
Fig. 5 is a schematic vertical section showing 20 supplied from a roll 24, and at the region of
the roller 26 where the resin coated ?lm on the
how the resin is applied in stripes;
non-adherent carrier is- still tacky, it is lami
Fig. 6 shows schematically how the tissue paper
to the coated Cellophane web. No great
, is laminated to a non-absorbent Cellophane web;
laminating pressure is required, and special pres
Fig. 7 schematically illustrates the separation
of the lamlnations and‘ the heating and slitting of N (1 sure rollers are unnecessary. In the present ap
paratus the laminated material is run over guide
the tissue paper web; v
rollers 28, 30, 32 and 84, which are offset rela
Fig. 8 is a fragmentary view explanatory of the
Fig. 4 shows‘ a piece of striped web prior to
' tive to one another, so that the laminated mate
slitting mechanism;
Fig. 9 is a perspective view showing the slit
rial runs in a zig-zag path.
This will alone
Fig. 10*i is a similarview showing a web coated
coated carrier is solely by interfacial contact,
develop suillcient pressure for the present pur
ting of the striped web;
‘ 30 pose. Thus, in this step of the process the lam
Fig. 10 shows a piece of narrow or slit web
inating of the tissue paper to the resin ?lm
coated with a mesh of reinforcing stripes;
that is to say, by direct face to face contact
Fig. 11 is a schematic vertical section showing a 35 without any relative slide or wiping motion and
with only relatively light laminating pressure.
modi?ed method of applying a resin coating to
laminated material is then vwound up into
the tissue paper;
a reel, indicated at 38.
Fig. 12 is a schematic vertical section of a still
For high-speed, economical production pur
further modi?cation; and
Fig. 13 schematically shows a further step that 40 poses, the webs employed are preferably of com
mercially available width far greater than that
may be used in the method of the invention.
needed for a tea bag. Where it is only desired
Referring to the drawings, and more particu
to coat the paper with sealing edges, the web _
larly to Fig. 6, where I show one of the ways of
may be coated with a plurality of spaced,\paral
practicing the method of my present invention,
lel stripes, a limited number being illustrated
_I employ a bath I! of vinyl resin. This is in liq
at 40 in Fig. 4. Each stripe is twice the width
uid form, preferably dissolved in a highly volatile
desired for the marginal edge of the tea bag,
solvent such as acetone. - The resin may be those
and the stripes are spaced apart by the desired
known commercially as Vinylite copolymer resin
width of the tea bag, so that when the web is
made by Union Carbide &-Carbon Corporation of .
New York city. These resins consist of vinyl chlo 50 slit on the broken lines 42, a number of narrow
for an over-all or ?ne mesh;
webs are obtained. In this way the entire web
ride and vinyl acetate. A speci?c example is their ' VYHF resin, comprising 85% to 88% of vinyl chlo
is used except for marginal waste 44 at the edges
of the main wide web. Fig. 5 shows ,how the
ride, and the balance vinyl acetate. Another sim
gravure roller I4 is knurled or etched at the
ilar coating, already dissolved, which may be used,
is the coating compound G357C of the Gordon 55 points 46, so as to apply the desired stripes to
the Cellophane web 48 held etween roller I4
Lacey Chemical'Products Company, of Long Is
and pressure roller 20.
land City, New York. The above /are mentioned
‘After a suitable drying period, the roll 38 of
by way of exempli?cation, and not in limitation,
laminated material is-unwound and the lamina
of the invention.
tions are separated, as shown in Fig. '7. The
Cellophane web 50 is rewound at 52, and is avail
able for repeated use. The tissue paper web
54 is preferably passed over a heating unit,
solution, and is acted on by means of a doctor
schematically indicated at 58, in order to drive
blade schematically indicated at is. "represents
a carrier, herein the form of a moving web or 65 off any remaining solvent or volatile ingredients.
This is readily done at moderate temperature
roll of material to which the vinyl resin is non
because the resin coating is a super?cial coat
adherent. ‘A very satisfactory material is plain,
lng localized on the surface of the paper. There
transparent regenerated cellulose, such as that
The coating roller l4 shown in Fig. 6 is a gra
vure roller formed by knurling, etching, or other
suitable process. It runs in the bath of resin
sold commercially by the E. I. dulPont de Nemours '
Co., under the name Cellophane. However, glass 70
ine or wax paper may also be used. The web of
Cellophane is fed between the ‘roller i4 and a
backing or impression roller 20, which ordinarily
is made of rubber. The coated web is led around
guide rollers for a distance su?icient to insure
is no impregnation into the full body of the
The web then passes through appropriate slit
ting means, here illustrated as comprising simply
a grooved roller 58 cooperating with a series of
spaced cutting blades or razor blades 60. These
parts are also shown in Figs. 8 and 9. The a‘
resulting‘ narrow webs are reeled,‘it being con
venient to wind alternate webs on a shaft 02
while the intermediate webs are separately
ence thereof to the paper ?bres. ‘ Thereby the
wet strength of the paper is-greatly increased by
the resulting water-proo?ng of the .?bres of the
and thereby the desired infusion charac
clear from Fig. 9, showing how the webs BI s teristics of the paper are retained byjthe break
and 88 run of! horizontally, while the webs ‘I0. . ing down or perforating of the resin ?lm at the "
and 12 run downwardly.
wound on a spaced shaft 64. This will also be
paper pores. If the paper were fully impreg
It will be understood that each of the result!
with resin the waterproo?ng would pre
ing narrow reels is later used to supply an appro
vent disintegration and so. increase the wet
priate packaging machine, which in turn per 10 strength, but the desired open~mesh character
forms operations of the general nature illustrated
of the paper would be lost. With my process the
in Figs. 1, 2 and 3. Speci?cally, the narrow web
of resin available is so limited that on
is cut into lengths as shown in Fig. l, and is
heating and absorption the ?lm must break down
folded to bring the coated edges together, as _ at the pores of the paper, the gain in depth being
shown in Fig. 2. These edges are subjected to 15 lost in area.
heat and pressure in order to heat-seal the resin.
The bag is ?lled with a measured quantity of tea
excessive, and, therefore, does not damage the
or other food product, and is closed at the top.
paper. This situation is to be contrasted with
-In the case of a tea bag, it is unnecessary to
the condition which would exist if the original
seal the top, for it may be closed by the same 20 coating of resin were applied directly to the tis
string, which is anyway needed to suspend the
sue paper (or if a thicker ?lm or coating were
same in the tea pot. It will be understood that
applied), for insuch case. a much larger quan
when the bags are made and ?lled automati
of the resin solution would be required, and
cally, the measured quantity of tea may be de
would be absorbed into the paper, and a much 7
posited on the blank before the blank is folded 25 higher
temperature would be needed to both
and heat-sealed, instead of‘after. This depends
drive out the solvent and to‘shrink and break
on the nature of the particular bag-forming and
up the impregnated ?lm or resin, it it could be
?lling machine used.
broken up at all into a perforate condition. In
In the form of the invention just described,
such case the temperature required, if workable
the vinyl resin has been used solely as a-seal 30 at all, would be‘so high as to char and weaken
ing medium. It may, however, also be used to
the paper. There would also be the initial dif
increase the wet strength of an otherwise weak
?culty of the resin penetrating the paper and
tissue paper. This is illustrated in Fig. 10, in
sticking to the backing roll.
which it will be seen that the narrow web ‘I4 is
crossed by intersecting stripes 18, ‘I8, 80, etc. 35 it is important to employ the right thickness of
These form an open mesh, which does not pre
vent the desired ?ltration or diffusion, but which,
nevertheless, functions to strengthen the paper.
?lm for best results, when seeking to improve
the wet strength of the tissue as described above.
If the ?lm of vinyl resin deposited on the Cello
It will be understood that the piece of web
phane and then transferred to the tissue paper,
shown in Fig. 10 is a piece of the narrow or slit 40 is too heavy, the resin will tend to clog the in
web, and that a single side web may be coated - terstices between the ?bres of the tissue paper,
to form a considerable number of narrow webs.
thus obstructing ?ltration and diffusion. If, on
The only change needed'is in the gravure roller
the other hand, the resin ?lm used is too ‘light.
i d, which should be appropriately etched to print
it may not add suillciently to the wet strength of
the reinforcing lines or mesh, as well as the mar 45 the paper. Another variable factor is the nature
ginal sealing lines. The latter may be etched
of the tissue paper itself. For many types I have
to greater depth, if a thicker sealing ‘coat is"
found that the ?lm deposited by using agravure wanted. _It will also beunderstood that the num
roller etched to a depth of time Of an inch, is
ber of reinforcing lines maybe increased, thus
satisfactory. Different types of tissue paper may, a
making the mesh much ?ner than that illus 50 however, have a different degree of'openness
trated in Fig. 10. For example,‘ I may use a
between the intermatted ?bres oi’ the paper, and
roller having a mesh of 100 to the inch.
thus may require different amounts of the vinyl
In fact, the ?neness of the mesh may be in
creased until the elementsare practically in
Reference has been made to filtration as well
?nitesimal in size, but for this purpose the proc 55 as di?’usion. In a sense, a tea bag acts as a ?lter,
ess is preferably modi?ed. Speci?cally, the en
but the present invention is applicable to ?ltra
tire web is preliminarily coated with a very thin
tion in a more direct sense, as for example, in
super?cial coating of resin. Whenthis web is
drip-type coffee-makers. The wet strength of _
subjected to the ?nal heating step illustrated in
the ?lter paper used may be increased, as de
Fig.‘ 7, the temperature is elevated enough not
only to drive oil residual volatile solvent, but also
to actually melt or break down the resin coating.
'Ihe coating tends to melt into the absorptive
60 scribed above.‘
A modi?edv form of apparatus involving a
modi?cation of the method is shown in Fig. 11
of the drawings. The main difference is that the
laminated formation is not reeled up. In this
paper, thus breaking up the coating from a con
tinuous surface to a highly perforate surface. 65 form of the invention a Cellophane web carrier
The resin coating prior to this heat treatment
92 is taken from a roll Bland is coated at 86
is a very thin and super?cial but continuous
a ?lm of the resin solution from the bath
coating. The degree of heat necessary for this
38.‘ Between the coating roller 88 and the pres
operation is only such as to cause the resin at
sure rolls 90, the resin ?lm on the moving web
the pores or interstices of the paper to break up
is treated as before to effect partial evapora-‘
and ?ow into the paper. The resin coating which
tion of the solvent in the resin, leaving the ?lm
exists over the paper ?bres remains in a con
partially dried and in a still tacky condition
tinuous condition, the applied heat effecting
the region of the pressure rolls 90. Here the
however, a partial penetration of this part of
treated resin ?lm is contacted with the tis
?lm, and, therefore, causing a more ?rm adher 76 thus
sue paper web 92 taken from a roll 94 and the
two are run together as a laminated assembly
between the staggered rolls 90, 00, 00 and I00.
peratures and low pressures throughout the prac
tice of theprocessv in its various modi?cations
The two webs are then separated, the carrier
web 32 being reeled up at I02 and the tissue
is evident. "Tissue or porous paper is a relatively
blower I08 may be connected at the discharge end
of the tunnel and may be used to blow a stream
the particular products involved.
weak structure and onew-hich is not capable of
paper 'web being passed through a drying tunnel 5 being treated, without some damage to the paper
structure, at high temperatures or high pres
I04 and then reeled up at I08. In separating the sures. In the practice of the process, therefore,
carrier and- the tissue paper the resin coating
the transfer of the resin ?lm and the complete
transfers from the carrier and. becomes adher
elimination of the solvents is accomplished sim-.
ingly attached to the contacted surface of‘the
tissue paper. The residual solvent in the resin 10 ply and in a practical way with low pressures and
temperatures and also both quickly in point of
"?lm (or the'solvent which has become absorbed
time and rapidly in point of apparatus space.
in the ?bres of the tissue paper) is completely
A further important consideration'in being able
removed in the drying tunnel I04. In this dry
to do all this at the low temperatures is elimina
ing tunnel, air movement or heat, or both, may
be used to dry the paper web. For example, a 15 tion of ?re and explosive hazards in dealing with
of‘ air through the tunnel and out through the
In Fig. 12 of the drawings, 1 show how the
invention may be practiced with‘a non-adherent
character of a different form, namely, in the form
be disposed along the top of the tunnel. Either 20 of atransfer roll. Here the resin solution in the
bath H4 is coated by means of a steel engraved
or both ,of these expedients may be used, and
roll II! on to a large diameter transfer roll H0.
the air velocity and temperature required de
- This transfer roll may comprise a rubberlroll
pends almost wholly on the desired speed of
. open inlet H0. Electricalheating units II2 may
with a non-compatible or non-adherent facing
movement of the coated web. Where the entire '
surface of the tissue paper web has been transfer 25 II.B'b made of gelatine, wax, etc.,’the roll thus
having a cushioning base and the desired non
coated, the heat in the tunnel I04 is such as to
adherent facing. Between the point of applica
effect the dual result of perforating the coating
tion I I8 (of the resin coating to the transfer roll)
and causing the particles to melt and adhere to
and the region I20, the resin solution ?lm ap
the paper ?bres, thereby accomplishing the dual
‘function of increasing the wet strength of the 30 plied‘ to the transfer roll is treated to effect par
tial evaporation of the solvent, leaving the ?lm
paper and producing a perforate coating and,
therefore, a ?ltration and infusion resin’ coat
- at the region I20 partially dried and in a. still
tacky condition. At the region of point I20 the
thus treated ?lm on the transfer roll H0 is con
'In the form of the invention described in con
nection with Figs. 6 and 7, the laminated assem 35 tacted with a. web of tissue paper I22 taken from
the roll I24, the contact being between the trans
bly between the operations of Fig. 6 and Fig. 7
fer roll I I6 and a pressure roll I28. At the point
may be set aside to age. Such aging may take
of emergence I28 where the web of tissue paper,
anywhere from a few hours to two or three days.
separates from the transfer roll, the resin coating
The aging causes a certain amount of the solvent
in the resinous ?lm to be absorbed by the paper 40 on the transfer roll leaves the latter and becomes
adheringly attached to the contacted surface of
and become dissipated by the‘ ?lm itself, so that
the tissue paper, the tissue paper web being then
on the subsequent heating the solvent dissipates
wound up into the reel I30. If desired, ‘the re
very readily at a low temperature.
sidual solvent in the transferred resin coating
This aging step may also be practiced with the
method described in connection with Fig. 11 of 45 may be removed between the pressure roll I23
and the reel I30 in the manner aforedescribed,
the drawings. In doing so, the heating step de
or the reel I30 may be set aside to age and may
picted for Fig. 11 ‘is carried out at a relatively
ing- characteristic.
lower temperature, the heating being just su?i- ‘ _ thereafter be passed through a heating tunnel
or ‘over a heating‘ means in the manner afore
cient to cause a goodly portion of the residual
solvent‘ to be driven oh and to cause a firmer 50 described in connection with Fig. 11 or Fig. 7 of
the drawings for effecting the removal of the re
anchorage of the resin ?lm on to the paper ?bres.
solvent from either the resin coating or
The paper roll I08 is then set aside to age. This
the resin coated tissue paper and for effecting
aging causes the remainder of the solvent in the
the breaking up of the ?lm into a discontinuous
resinous .?lm to be absorbed by the paper ?bres
and to become otherwise dissipated by the ?lm 55 paper ?bre adherent perforate condition.
In Fig. 13 of the drawings, I show a further
itself. Thereafter, this roll may be unreeled and
operating step that is sometimes desirable in this
passed over one or more heating units according
last mentioned stage of the process. Here the
to the step depicted in Fig. '7 of the drawings.
reel I32 of tissue paper, after the aging opera
This ?nal heating stage functions to effect the
breaking up or perforating of the‘resin ?lm and 30 tion, is unreeled and passed over the heater I34
and re-reeled at I30. At the point of re-r'eeling,
the driving off of the remaining solvents present.
the paper is subjected to the application of a
By utilizing these two heating steps, the desired
water spray coming from the spray device I38. I
result may be effected with the employment of
have found that sometimes the ?ne tissue paper
low temperatures in each of the heating steps.
This aging step may also be employed to carry 65 may become embrittled by the last heating step
when moved over the heater I34. To re-intro
out the method of Fig. ll. by eliminating the
duce the desired flexibility of the paper and to
heating in carrying out the step of Fig. 11, de
remove the brittleness, I have found it efficacious
ferring the same until after the paper has been
to use a very ?ne spray of water on the reeling
reeled up and aged. In this latter event the
heating step after the aging is carried out at such 70 paper, just about at the point where it is being
?nally reeled up. The water becomes absorbed
temperatures (also moderate) as will effect the
throughout the paper ?bres and re-imparts the
dual function of driving of! all of the residuary
desired ?exibility to the paper.
solventand of breaking up the continuous resin
The practice of the method of the present in
?lm into the perforate ?lm described.
The importance of being able to use low tem 75 vention, the nature of the products‘ produced
thereby J and the advantages thereofiwill in the
3. The continuous method of surface coating 9.
main be fully apparent from the above detailed
web of tissue paper with a thermo-responsive res
description thereof. It will also be apparent that
while I have shown and described the invention
in, which consists in ?rst coating a thin ?lm of a‘
solution, of the resin on a moving non-adherent
Web carrier, in treating the applied ?lm on the
moving carrier to effect partial evaporation of the
solvent leaving the ?lm partially dried and in a
in a number of preferred forms, many changes
and modi?cations may be made, Without‘depart
ing from the spirit of the invention as sought to
‘be de?ned in the appended claims. While par
still tacky condition, in then laminating solely
ticular vinyl co-polymers have been found to be
by interfacial contact the moving web carrier with
most effective, other thermoplastic resin solutions 10 a moving web of tissue paper with the thus treat
or thermosetting resin solutions may be substi
ed ?lm on the carrier contacting the tissue paper,
> tuted therefor. The resin used may be pigmented,
in then aging the laminated assembly, thereafter
thereby coloring as well as coating the paper web.
separating the web carrier and the web of tissue
Cellophane and glassine' Webs have been found
paper, the resin ?lm thereby transferring from
quite e?icient; and waxed paper may be also ef
the web carrier and becoming adheringly attached
fectively used. Waxed paper when used should
a thin super?cial ?lm to the contacted surface
desirably not be subjected to heat; air drying
of the web of tissue paper, and in then heating
should be used before laminating the same with
the resin coated tissue paper, thereby driving off
the porous web; of course, heat may be applied
any residual solvent and thereby breaking down
to the porous web after it has been separated
the continuity of the resin ?lm to form an‘open
from the waxed paper web. A cloth fabric hav
mesh which increases the wet strength of the tis
ing the same characteristics and presenting the
sue paper without sealing it against ?ltration or
same problems as a tissue or ?lter paper may be
similarly coated; the invention is of particular
advantage and unique value with very soft, po
rous, or highly absorbent materials.
4. The method of applying to a tissue paper
‘web a porous thermo-responsive resin ?lm which
consists in ?rst applying on to the tissue paper
web a very thin super?cial ?lm of a thermo-re
’ ,
1. The method of surface coating a tissue paper
sponsive resin derived from a solution of the resin,
with a thermo-responsive resin, which consists in
and in then heating the tissue paper web and
?rst coating a thin ?lm of a solution of the resin 30 applied ?lm thereby breaking down the continu
on a non-adherent carrier, in‘ treating the car
ity of the resin ?lm at the pores of the tissue
rier ‘applied ?lm to effect partial evaporation of
paper web and thereby forming a porous or per
the solvent leaving the ?lm partially dried and in
forate resin ?lm on the tissue paper web.
5. The method of applying to a tissue paper
a still tacky condition, in then enga'ging solely
web a porous thermo-responsive resin ?lm which
by interfacial contact the thus treated ?lm on
I claim:
the carrier with the tissue paper, in then separat
consists in ?rst applying onto the tissue paper
web a very thin super?cial ?lm of a tlhermore
ing the carrier and the tissue paper, the resin
?lm thereby transferring from the carrier and
sponsive resin derived from a solution of the resin
becoming adheringly attached as a thin super
and which is still in a tacky condition, and in
?cial ?lm to the contacted surface of the tissue 40 then heating the tissue paper web and applied
?lm thereby removing residual solvent from the
paper, and in then heating the resin coated tissue
resin ?lm and. thereby breakingdown the con
paper and breaking down the continuity of the
tinuity of the resin ?lm at the pores of the tissue
resin ?lm to form an open mesh which increases
paper web and thereby causing the resin ?lm to
the wet strength of the tissue paper without seal
become more adheringly attached to the ?bres of
ing it against ?ltration or infusing.
the paper and producing a porous or perforate
2. The method of surface‘coating a tissue paper
resin ?lm on the tissue paper.
with a thermo-responsive resin, which consists in
?rst coating a thin ?lm of a solution-of the resin
on a non-adherent carrier. in‘ treating the carrier
applied ?lm to effect partial evaporation of the
solvent leaving the ?lm partially dried and in a
6. The method of applying to a tissue paper I
web a porous thermo-responsive resin ?lm which
consists in ?rst applying onto the tissue paper
still tacky condition," in then engaging solely by
web a verythin super?cial continuous :?lm of a
vinyl copolymer resin derived from a solution of
interfacial contact the thus treated ?lm on the
the‘resin, and in then heating the tissue paper
carrier with the tissue paper, in then separating
web and applied film- thereby breakingdown the
the carrier and the tissue paper, the resin ?lm
thereby transferring from the carrier and becom- ,
ing adheringly attached as a thin super?cial ?lm
to the contacted surface of the tissue paper, and
continuity of the resin ?lm at the pores of the
porous .web and thereby causing the resin ?lm to
become; more adheringly attached ‘.to the ?bres of
the paper and thereby forming an adherent po
runs or perforate resin film on the tissue paper,
in then heating the resin .coated‘tissue paper,
thereby driving off any, residual‘ solvent and 60,
breaking down the continuity ofthe resin film to 7
mvme onnwrcx.
form an open mesh ?lm which increases the wet
strength of the tissue paper. . , a
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