Note: Descriptions are shown in the official language in which they were submitted.
'7~5
~ 3L_und of the Invention
Field of the Invention
This invention relates to pressure sensitive
copying systems, and more particularly to a process for
the production of a manifold carbonless form and to the
carbonless form itself.
Prior Art
Manifold forms for commercial and private use
have been in common use for several years. Historically,
the standard business form has taken a variety of shapes.
The most common is a multiple part form with sheets of
carbon paper being insertable between the various sheets.
This concept is very cumbersome as the carbon paper had
to be both inserted, removed and disposed of in addition
to the deficiences commonly noted in the use of carbon
paper such as smudging. In response to the obvious prob-
lems a form was developed having the carbon paper already
inserted between the various sheets making up the form and
being available for easy removal and disposal. This re-
moval and disposal was made even more convenient by theattachment of the carbon paper together at one edge,
generally the bottom, so that by merely ripping out the
bottommost edge of the form all of the carbon paper would
be removed. This system has been and still is being used
by many retail department stores. All of these systems
have historically suffered from one common deficiency,
namely the use of carbon paper. Carbon paper, while
adequate for some image transfer purposes is not a prefer-
red product as it is very cumbersome to work with, it is
very messy and in general does not form the quality image
which is desired. In addition, as is commonly encountered
with the use of carbon paper the more sheets of carbon
paper that are used the fainter the image on the last sheets
-2-
`7~
of the form. This is especially true where more than
three to four sheets per form are used. Examples of
patents relating generally to the use and manufacture of
carbon paper and other image transfer systems containing
dyes and pigments are:
U.S. Patent 2,299,694 (1942) to Green
U.S. Patent 2,374,862 (1945) to Green
U.S. Patent 3,016,308 (1962) to Macauley
U.S. Patent 3,020,170 (1962) to Macauley
U.S. Patent 3,079,351 (I963) to Staneslow et al
In recognition of the deficiencies of carbon
paper as an image transfer media a variety of new products
have been introduced into the marketplace. One such pro-
duct is commonly referred to as carbonless paper. Carbon-
less paper, briefly stated, is a standard type of paper --
wherein during manufacture the backside of the paper sub-
strate is coated with what is referred to as a CB coating,
the CB coating containing one or more colour precursors
generally in capsular form. At the same time the front
side of the paper substrate is coated during manufacture
with what is referred to as a CF coating, which contains
one or more colour developers. Both ~he colour precursor
and the colour developer remain in the coating composi-
tions on the respective back and front surfaces of the
paper in colourless form. This istrue until the CB and
CF coatings are brought into abutting relationship and
sufficient pressure, as by a typewriter, is applied to
rupture the CB coating to release the colour precursor.
At this time the colour precursor contacts the CF coating
and reacts with the colour developer therein to form an
image. Thus the image from the top sheet is transferred
to the next sheet without the use of carbon paper. Car-
bonless paper has proved to be an exceptionally valuable
-3-
image transfer media for a variety of reasons only one of
which is the fact that until a CB coating is placed next
to a CF coatiny both the CB and the CF substrates are in
an inactive state as the co-reactive elements are not in
contact with one another. Patents relating to carbonless
paper products are:
U.S~ Patent 2,712,507 (1955) to Green
U.S. Patent 2,730,456 (1956~ to Green et al
A third generation product which is in an advan-
ced stage of development and commercialization at this timeand which is available in some business sectors is referred
to as self-contained paper. Very generally stated self-
contained paper refers to an image transfer system wherein
only one side of the paper needs to be coated and ~he one
coating contains both the colour precursor, generally in
- encapsulated form, and the colour developer. Thus when
pressure is applied, again as by a typewriter or other
writing instrument, the colour precursor capsule is ruptu-
red and reacts with the surrounding colour developer to
form an image. Both the carbonless paper image transfer
system and the self-contained transfer system have been
the subject of a great deal of patent activity. A typical
autogeneous record material system, earlier sometimes
referred to as "self-contained" because all elements for
making a mark are in a single sheet, is disclosed in U.S.
Patent 2,730,457 (1956) to Green.
In an especially preferred embodiment of this
invention the manifold paper product is produced continu-
ously without requiring roll storage or the like. As can
be appreciated from the above the continuous production of
a manifold paper product would require simultaneous coating,
simultaneous drying, simultaneous printing, and simultaneous
collating and finishing of a plurality of paper substrates.
7''~
Because of the complexities of the drying step this has
not been commercially possible to date. More particularly,
the drying step involving solvent evaporation and/or water
evaporation and the input of heat does not permit the simul-
taneous or continuous manufacture of manifold forms.
A disadvantage of coated paper products such as
carbonless and self-contained stems from the necessity of
applying a liquid coating composi~ion containing the colour
forming ingredients during the manufacturing process. In
the application of such coatings volatile solvents are
sometimes used which then in turn requires evaporation of
excess solvent to dry the coating thus producing volatile
solvent vapours. An alternate method of coating involves
the application of the colour forming ingredients in an aque-
ous slurry, againrequiringrémoval of excess waterby drying.
Both methods suffer from serious disadvantages. In parti-
cular the solvent coating method necessarily involves the
production of generally volatile solvent vapours creating
both a health and a fire hazard in the surrounding environ-
ment. In addition, when using an aqueous solvent systemthe water must be evaporated which involves the expenditure
of significant amounts of energy. Further, the necessity
of a drying step requires the use of complex and expensive
apparatus to continuously dry a substrate which has been
coated with an aqueous coating cQmpound. A separate but
related problem involves the disposal of polluted water.
The application of heat not only is expensive, making the
total paper manufacturing operation less cost effective,
but also is potentially damaging to the colour forming
ingredients which are generally coated onto the paper sub-
strate during manufacture. High degrees of temperature in
the drying step require specific formulation of wall-
forming compounds which permit the use of excess heat. The
-5-
lL~ 5
problems encountered in the actual coating step are gene-
rally attributable to the necessity for a heated drying
step following the coating operation.
The drying step involving solvent evaporation
and/or water evaporation and the input of heat does not
permit the most economic and efficient manufacture of mani-
fold forms. In addition to the drying step which hinders
manifold form production the necessity for the application
of heat for solvent evaporation is a serious disadvantage
since aqueous and other liquid coatings require that spe-
cial grades of generally more expensive paper be employed
and even these often result in buckling, distortion or
warping of the paper since water and other liquids tend to
strike through or penetrate the paper substrate~ Addi-
tionally, aqueous coatings and some solvent coatings are
generally not suitable for spot application or application
to limited areas of one side of a sheet of paper. They
are generally suitable only for application to the entire
surface area of a sheet to produce a continuous coating.
Patents considered relevant to this concept are:
Canadian Patent 945,443 (1974) to Busch
U.S. Patent 3,914,511 (1975) to Vassiliades
Another problem which has been commonly encoun-
tered in attempts to continuously manufacture manifold
forms has been the fact that a paper manufacturer must
design paper from a strength and durability standpoint to
be adequate for use in a large variety of printing and
finishing machines. This requires a paper manufacturer to
evaluate the coating apparatus of the forms manufacturers
he supplies in order that the paper can be designed to
accommodate the apparatus and process designed exhibiting
the most demanding conditions. Because of this, a higher
long wood fiber to short wood fiber ratio must be used by
j~r;,,
~L~ 7~
the paper manufacturer than is necessary for most coating,
printing or finishing machines in order to achieve a pro-
per high level of strength in his finished paper product.
This makes the final sheet product more expensive as the
long fiber is generally more e~pensive than a short fiber.
In essence, the separation of paper manufacturer from
forms manufacturer, which is now common, requires that the
paper manufacturer overdesign his final product for a
variety of machines, instead of specifically desiyning the
paper product for known machine conditions.
By combining the manufacturing, printing and
finishing operations into a single manufacturing facility
a number of advantages are achieved. First, the paper
can be made using ground wood and a lower long fiber to
short fiber ratio as was developed supra. This is a cost
and potentially a quality improvement in the final paper
;~ product. A second advantage which can be derived from a
combination of manufacturing, printing and finishing is
that waste or recycled paper hereinafter sometimes refer-
red to as "broke" can be used in the manufacture of the
paper since the quality of the paper is not of an over-
designed high standard. Third and most importantly,
several steps in the normal process of the manufacture of
forms can be completely eliminated. Specifically drying
steps can be eliminated by using a non-aqueous, solvent-
free coating system and in addition several warehousing
and shipping steps can be avoided thus resulting in a more
cost efficient product.
Additionally, by using appropriate coating me-
thods, namely non-aqueous, solvent-free coating composi-
tions and methods, and by combining the necessary manufac-
turing and printing steps, spot printing and spot coating
can be realized. Both of these represent a significant
--7--
X
7 . ~ ~ ~
cost savincJs but nevertheless one which is not generally
availabl~ when aqueous or solvent coatings are used or
where the manufacture, printing and finishing of paper
are performed at ~eographically separated manufacturing
facilities. An additional advantage of the use of solvent-
free, non-aqueous coating compositions and the combination
of paper manufacturer, printer and finisher is that when
the option of printing followed by coating is available
significant cost advantages occur. More particularly, by
printing prior to coating from about 10% to about 30% fewer
capsulated colour forming ingredients need to be used to
achieve the same satisfactory levels of image transferabi-
lity. This advantage is realized because when the paper
is transferred to a forms manufacturer in coated form the
paper of necessity will lose some of its capsulated colour
formers when printed because of the pressure rupturability
of the material. This disadvantage is eliminated when the
paper is printed first followed by coating.
Many of the particular advantages of the process
and product of this invention are derived from the fact
that a non-aqueous, solvent-free coating composition is
used to coat the paper substrate. This is in contrast to
the coatings used by the prior art which have generally
required an aqueous or solvent coating. For purposes of
this application the term "100~ solids coating" will some-
times be used to describe the coating operation and should
be understood to refer to the fact that a non-aqueous,
solvent-free coating composition is used and therefore the
normal drying step normally present in the manufacture of
paper and in coating has been eliminated.
The present invention provides a process for the
production of a manifold carbonless form having two or more
surfaces coated with chromogenic material comprising:
~;-
r 7 ~ 5
(a) providing a continuous web said continuousweb having a first and second surface;
tb) marking said second surface of said conti-
nuous web with a pattern;
(c) applying a first non-aqueous, solvent-free
coating of a first chromogenic material to at least a
portion of said first surface of said continuous web said
first non-aqueous, solvent-free coating comprising said
: firs chromogenic material dispersed in a hot melt suspen-
ding medium, said coating being heated to a temperature
above the melting point of said hot melt suspending medium
to permit fluid application of said first coating composi-
tion to said first surface;
(d) setting said first coating by means of
temperature decrease to form a marked, coated continuous
web;
~- (e) combining said printed, coated continuous
web with at least one additional continuous web to form a
, plurality of continous webs,
(i) each of said additional continuous webs
having a first and second surfacel
(ii) each of said additional continuous webs
~ being characterized by having at least a portion of the
- second surface thereof coated with a second chromogenic
material, said second chromogenic material being coreactive
with said first chromogenic material to form a colour,
(iii) all except one of said additional con-
tinous webs being further characterized by at least a por-
tion of the first surface thereof being coated with at
least one non-aqueous, solvent-free coating of said first
chromogenic material, said non-aqueous, solvent-free
coating on said first surface of all except one of said
additional continuous webs comprising said first
X
chromogenic material dispersed in a hot melt suspending
medium,
(iv) said coating on said first surface of
all except one of said additional continuous webs being
heated to a temperature above the melting point of said
hot melt suspending medium to permit fluid application
thereof,
(f) setting said coating on said first surface
on all except one of said additional continuous webs by
means of temperature decrease;
(g) collating said plurality of printed coated
continuous webs such that coreactive chromogenic materials
are in facing relationship; and
(h) placing said collated continuous webs in
contiguous relationship to one another to create a mani-
fold carbonless form.
Detailed Description of the Preferred Embodiment
. .
The process of this invention is directed to the
complete production of manifold carbonless forms at a single
processing or manufacturing facility. The term "carbonless"
as used herein shall be understood to be a generic term to
; encompass any t~pe of image transfer paper or paper system
not requiring the use of carbon paper. The carbonless
paper will be described herein as having a topmost and
bottommost surface corresponding to those surfaces as they
would appear to a person using the paper. One, both or
none of the surfaces of the carbonless paper can be coated
with a chromogenic material in the form of microcapsules,
droplets or other vehicle dispersed in a binder. Prefer-
ably the capsular material is microencapsulated. Included
in the chromogenic materials are colour precursors, colour
developers, colour inhibitors and like materials and oom-
binations thereof.
-10-
7 v .~ ~
The manifold carbonless forms of this invention
will usually comprise from about 2 to about 10 individual
sheets and preferably from about 2 to about 4 individual
sheets per form. The actual number of sheets or layers
making up the particular carbonless form is not limiting
to the practice of the process of this invention, but
rather can be manufactured to the convenience of the indi-
vidual customer.
The apparatus which can be used in the process
of this invention includes apparatus which is traditionall~
used in paper manufacturing and forms printing. During the
collating and/or finishing steps as the various continuous
webs are advanced towards their final finishing or packing
- station they must be advanced at substantially the same
speed and other process variables must be specifically
controlled. For example, if the individual paper webs are
various colours indicating second or third copies the col-
lating must be coordinated so that the colours of the forms
are properly arranged. Additionally, it is preferred al-
though not essential that the size of the individual con-
tinuous webs be substantially equal. It is necessary in
the manufacture of carbonless paper forms that the CB/CF
coatings be adjacent to one another; and finally it is
necessary that the distinction be made between carbonless
and self-contained so that two sides coated with a self-
contained coating composition are not adjacent to each
other. For purposes of this application the arranging of
the various sheets in the proper order shall be sometimes
referred to as collating the sheets, webs or substrates.
A particular advantage enjoyed by the process of
this invention is the fact that the printing or marking
step can be completed prior to the coating step. In this
fashion it can be seen that fewer encapsulated materials
-11-
~L~37~3~5
need be coated on the paper as from about 10% to about 30%
of the encapsulated material which is normally ruptured or
otherwise destroyed during the printing operation is not
necessary as the web has already been printed during the
coating operation.
The continuous webs, sometimes referred to here-
in as substrates, are any of those commonly used in the
manufacture of carbonless papers. Included in the prefer-
red continuous web materials are paper and plastic although
other substrates can be substituted. The continuous webs
can be supplied in any of a variety of shapes, sizes and
configurations. The preferred and most common shape is in
a roll form. While the particular dimensions of the roll
; are not critical a standard roll would be sized at approxi-
mately a width of from about 3 inches to about 72 inches
and a total length of approximately from about 500 feet to
about 10,000 yards. This particular size has been found
suitable to fit more printing and coating apparatus~ In
this fashion a substrate is printed and coated and then
stored for future use in combination with other compatible
printed and coated substrates to make a finished manifold
carbonless form. After the individual treated substrates
have been stored they are placed in collating and finishing
apparatus to complete the manufacturing process. In an
alternative embodiment the continuous web can be supplied
as an on-line substrate forming process. In this parti-
cular embodiment the manifold carbonless form ~lanufacturing
process is the final stage in the paper making process.
The preferred continuous web material is paper
and as developed supra the overall quality of the paper
can be somewhat lower than was previously considered accep-
table and as a result the paper can generally be made using ~`
some ground woods and additionally the paper has a lower
-12-
3'~C3~
long fibre to short fibre ratio. This cost saving advan-
tage of lower overall paper quality is realized because the
paper can be manufactured specifically for use in combina-
tion with known coating and printing apparatus.
A particular advantage enjoyed by the process of
this invention is the fact that the printing or marking
operation can be completed prior to the coating step. In
this fashion it can be seen that fewer encapsulated materi-
als need be coated on the paper as from about 10~ to about
30% of the encapsulated material which is normally ruptured
or otherwise destroyed during the printing operation is not
necessary as the web has already been printed during the
coating operation. This is in contrast to what was previ-
ously possible due to the fact that formerly after any
coating step a drying step was of necessity required, the
drying step generally requiring the application of substan-
tial heat and the expenditure of a significant amount of
energy. This represents a substantial cost and convenience
advantage over any methods shown or disclosed by the prior
;~ 20 art.
As described above in the preferred process of
this invention the individual substrates are subjected to
a printing or marking step prior to the coating step. While
this is preferred it is not critical. For purposes of this
application the term "marking" shall be used and shall be
understood to be generic to printing, writing, lining or
any other marking of a continuous web whether the marking
is visible or not. In the preferred process of this inven-
tion the topmost surface of each individual web of the
plurality of continuous webs is marked with a printing ink
to provide the printed information and blanks usually found
in a business form. However, it is sometimes the case that
only one surface, normally the topmost surface, of the
-13-
X
~ t~c~ 5
topmost continuous web will be so marked. The actual con-
tent of the marking and the number of webs which are marked
are dependent on the particular form being manufactured and
may be conveniently adjusted during the manufacturing opera-
tion.
In the preferred embodiment of this invention the
marking step is performed by the application of a marking
fluid, preferably a printing ink, by suitable printing appa-
ratus to one or more surfaces of the continuous webs. The
preferred printing method is offset although any of the
other well known printing methods are equally applicable.
The actual printing method is merely an apparatus limitation
and depends on the printer capabilities of the particular
manufacturer. The inks which can be used in this printing
step are any of the inks commonly used in the printing in-
dustry today. The ink must only be selected from a group
;~ or type which are compatible with the coating process and
composition.
For the production of manifold carbonless forms
according to the process of this invention it is necessary
that at least one coating composition be applied to at least
one surface of at least one continuous web prior to colla-
ting into a manifold form. In the preferred embodiment of
this invention each continuous web of the plurality of con-
tinuous webs, except the topmost web, will have a CF coating
containing a colour developer on the topmost surface and a
CB coating containing an encapsulated colour precursor on
the bottommost surface. As another preferred embodiment a
self-contained image transfer system can be used wherein
both the colour developer and colour precursor are coated
on a single surface, preferably the topmost surface, of
each continuous web again with the exception of the topmost
web which does not require any coating material regardless
-14-
-X
r7tl~
of what particular form o~ carbonless transfer system is
used.
Depending on the particular coating method and
composition the coating of a self-contained composition on-
to the continuous web can require either one or two separate
coating steps. While the coating step can be performed by
a variety of known methods the preferred coating methods
and coating compositions are hot melt suspension media and
radiation curable resins. One of the particularly signifi-
cant advantages found in both of these preferred coatingmethods is that no coating drying step is necessary. Rather,
a curing or setting step is substituted for the drying step
and no heat, elapsed time or elevated temperatures are
necessary. Thus the coating compositions for use ih the
process of this invention are best described as solvent~free,
non-aqueous coating compositions or expressed differently
"100% solids coatings'l.
HOT MELT SYSTEM
The preferred coating method of this invention
involves the use of a hot melt suspension medium, preferably
waxes, resins or the like in combination with microcapsules,
-~ the microcapsules containing a colour precursor or colour
precursor combination. The most preferred hot melt suspen-
ding media comprise the low molecular weight polar waxes.
The hot melt suspending medium procedure described herein -
will be hereinafter sometimes referred to as the hot melt
; activation system. The hot melt activation system has
been found most suitable for use as the CB coatin~ for car-
bonless paper although to a somewhat lesser extent it can
also function as the CF coating containing the colour deve-
loper or colour developer combination. This preferred pro-
cedure involves microencapsulating a colour precursor using
any of a variety of well-known microencapsulation techniques
X -15-
7~
most of which re~uire the use of a cross-linking agent with
a wall forming compound to initiate an interfacial reaction
resulting in the formation of microcapsules having charac-
teristics determined by the particular wall forming compound.
The chromogenic coating composition for use in
the hot melt embodiment of this invention is essentially a
dispersion of a chromogenic material in a hot melt system.
The chromogenic material can be either soluble or insoluble
in the hot melt system and the colour precursors are prefe-
rably in microencapsulated or dispersed form. Fillermaterials can also be added to the hot melt to modify the
properties of the final coated substrate. The use of sol-
vents, which require heat to remove them during the setting
of the coated film, is avoided.
The chromogenic colour precursors most useful in
the practise of the hot melt embodiment of this invention
are the electron-donors and include the lactone phthalides,
such as crystal violet lactone, and 3,3-bis~ ethyl-2-
methylindol-3'-yl) phthalide, the lactone fluorans, such
as 2-dibenzylamino-6-diethylaminofluoran and 6-diethylamino-
1,3-dimethylfluorans, the lactone xanthenes, the leucoaura-
mines, the 2-(omega substituted vinylene)-3,3-disubstituted- -~
3-H indoles and 1,3,3-trialkylindolinospirans. Mixtures of
these colour precursors can be used if desired. In the pre-
ferred hot melt process of this invention microencapsulated
oil solutions o~ colour precursors are used. The colour
precursors are preferably present in such oil solutions in
an amount of from about 0.5~ to about 20.0% based on the
weight of the oil solution, and the most preferred range
is from about 2~ to about 7%.
The hot melt suspending media generally useful in
the practise of this invention include waxes and resins.
The preferred group of compounds useful as hot melt suspending
-16-
media include: deresinatecl, oxidized mineral waxes such
as the montan waxes, amide waxes such as bis-stearamide
wa~, stearamide wax, behenamide wax, fatty acid waxes, hy-
droxylated fatty acid waxes, hydroxy stearate waxes, oxa-
zoline waxes, amine waxes and mixtures thereof. The hot
melt suspending medium is characterized by having a pene-
tration hardness of less than or equal to from about 0.1
to about 20.0, a melting point of from about 60C to about
140C, a narrow melting range, a low viscosity when molten,
a certain amount of polarity and a light colour. Any wax
or wax mixture with the foregoing properties can be used
successfully as suspending media in the practise of this
invention. These waxes are all suitable to act as a dis-
persing medium for the chromogenic material and other in-
gredients of the coating composition and at the same time
; are compatible with the chromogenic properties of the chro-
mogenic material. These materials are settable to a solid
when cooled.
Included in the preferred group of hot melt sus-
pending media are the following waxes: 2-n-heptadecyl-4,4-
bis-hydroxy-methyl-2-oxazoline, N,N'-ethylenebisstearamide,
N- (2-hydroxyethyl)-12-hydroxystearamide, glyceryl mono-
hydroxystearate and ethylene glycol monohydroxystearate.
Other waxes of this type which have generally
proved to be effective are generically described as modi-
fied mineral type, synthetic waxes or those of vegetable
origin or combinations thereof. These waxes must be
characterized by a high melting point and a great hardness
which eliminates wax transfer to the developing sheet,
thus improving image clarity, increasing blocking tempera-
ture and diminishing packing problems. One of the most
preferred waxes for use in the process and product of this
invention are the deresinated crude montan waxes. These
X -17-
-
7~5~
waxes are produced from a raw material of bitumen-rich lig-
nite which is extracted with organic solvents to form a
crude montan wax. The montan wax is deresinated by extrac-
tion with organic solvents followed by oxidation with chro-
mic acid to yield acid waxes.
Another type of preferred hot melt suspending
media is a non-polar hydrocarbon wax, such as Be Square*
170/175 (m.p. range 170-175F) from Bareco Division of
Petrolite Corporation which includes a small amount of
dispersing agent. The dispersing agent may, for instance,
be Turkey Red Oil.
The preferred waxes of this invention have a
penetration hardness of from about 0.1 to about 20 measured
by the needle penetration test given a ASTM designation of
D1321-61T. The range of 0.1 to 20.0 represents a practical
penetration hardness range. A more preferred ranged is
from about 0.1 to about 3 and the most preferred range is
from about 0.1 to about 1 on the same needle penetration
index. The needle penetration index covers a test proce-
dure for the empirical estimation of the consistency of
~; waxes derived from petroleum by measurement of the extent
of penetration of a standard needle. This method is appli-
cable to waxes having penetration of not greater than 250.
The penetration of petroleum wax is the depth, in tenths
of a millimeter, to which a standard needle penetrates into
the particular wax under defined conditions. The defined
conditions generally are that the sample is melted, heated
to 30F above its melting point, poured into a container,
and then air cooled under controlled conditions. The
sample is then conditioned at test temperature in a water
bath. Penetration is measured with a penetrometer, which
applies a standard needle to the sample for 5 seconds under
a load of 100 grams.
* Trade Mark
-18-
~"3'~35~i
A second characteristic of the desired hot melt
suspending media of this invention is a melting point of
from about 60C to about 140C. A more preferred melting
point for the waxes or resins of this invention is from
about 70C to about 100C. Also relative to the melting
point, it is necessary for the coating composition of this
invention to set rapidly after application to the particu-
lar substrate. More particularly, a practical melting
range limitation, or in other words range of temperature
in which the li~uid hot melt composition sets into a solid
composition, is from about 1.0C to about 15C. The pre-
ferred setting time is from about 0.5 seconds to about 5
seconds while the most preferred setting time is from
; about 0.5 seconds to about 2 seconds. While melting ranges
of more than 15C can be used the time necessary for such
a coating composition to set requires special apparatus
and handling and makes use of these hot melt compounds
commercially unattractive.
The hot melt waxes and resins of this invention
must also have a low ~iscosity when in a molten state in
order to facilitate ease of spreading on the substrate.
In general, it is desirable that the hot melt suspending
media have a viscosity of less than about 120 centiposes
at a temperature of approximately 5 above the melting
point of a particular hot melt suspending medium. In addi-
tion, it is preferred that the hot melt wax or hot melt
suspending media of this invention havea light colour in
order to be compatible with the final paper or plastic
product being produced~ This means that it is preferred
for the hot melt to be white or transparent after applica-
tion to the particular substrate being coated.
The preferred waxes, resins and other hot melt
suspending media of this invention preferably are polar.
-19-
5~i
By polar it is meant that a certain amount of polarity is
characteristic of the preferred waxes, the polar composi-
tions being characterized by the presence of functional
groups selected from the group consisting of: carboxyl,
carbonyl, hydroxyl, ester, amide, amine, heterocyclic
groups and combination thereof. An alternative but less
preferred embodiment of this invention includes the use of
non-polar hydrocarbon waxes which must be used in conjunc-
tion with a dispersing agent.
The additives which may be included in the hot
melt CB coating composition are typically an opacifying
agent such as titanium dioxide or clay, a stilting agent
such as Arrowroot starch and wax modifying agents such as
polycinyl acetate, isophthalic polyester, or any other
resin materials soluble or dispersible in the main wax
and which improves wax quality.
The method of dispersing the microcapsules in
the hot melt suspending media is also important since it
is, likewise, necessary to use a process which prevents
significant agglomeration of the microcapsules. In the
preferred process the microcapsules are formed into an
aqueous slurry containing approximately 40% solids and are
then spray dried to form a free-flowing powder. The free-
flowing microcapsules are stirred into a molten phase of
a suspension medium, such as a wax, a mixture of waxes, a
; resin or mixture thereof to form a smooth dispersion of
microcapsules in the continuous molten phase. This hot
melt can then be coated or printed, by gravure, blade coa-
ting, flexography or other means onto the continuous web.
The hot melt system sets substantially immediately after
application to the web and forms an excellent marking
sheet.
In the most preferred embodiment of this invention
-20-
.~.4~3~5
a dispersing agent is added to the microcapsules prior to
combining the microcapsules with the hot melt suspending
mediu~. A preferred group of dispersing agents are the an-
ionic dispersing agents, many of which are commercially
available. A preferred group of anionic dispersing agents
includes the sodium salts of condensed naphthalene sulfonic
acids, the sodium salt of polymeric carboxylic acids, the
free acids of complex organic phosphate ester, sulfated
castor oil, poly-(methylvinyl ether/maleic and hydride)
and combinations thereof. The most preferred dispersing
agent is sulfated castor oil. The dispersing agent is
added to the microcapsules in an amount of from about 0.1
to about 10% based on the dry weight of the microcapsules.
A preferred range of addition is from about 0.5% to about
5.0~ based on the dry weight of the microcapsules while a
most preferred range is from about 1.0% to about 3.0% based
on the dry weight of the microcapsules.
In the most preferred embodiment of this inven-
tion a dispersing agent is added to the microcapsules prior
to combining the microcapsules with the hot melt suspending
; medium. In some instances the dispersing agent and the
wall forming material are one in the same and the wall for-
ming material not actually used in the microcapsule wall
formation is present in hot melt coating dispersion as a
dispersing agent. Although as described above many of the
well-known, commercially available dispersing agents can
be used in the process and product of this invention a
group of secondary dispersing agents that may be present
as excess wall forming material includes: hydroxypropyl-
cellulose, gum arabic, gelatin, polyvinyl alcohol, carboxy-
methylcellulose, and mixtures of the above.
While the dispersing agent can be added at any
point in the process of this invention prior to the setting
-21-
7s`~
of the coating composition, to achieve the most desirable
results the dispersing agent should be added to the micro-
capsules prior to combining the microcapsules with the hot
melt suspending medium. The particular amount of disper-
sing agent used is dependent on several variables inclu-
ding the particular type of microcapsule used, the particu-
lar type of hot melt suspending medium, the concentration
of the aqueous microcapsular slurry, the viscosity of the
hot melt suspending medium and the desired final coated
product. For purposes of this application a practical
range of addition based on the weight of the microcapsules
is from about 0.1 part by weight to about 10.0 parts by
weight. A preferred range of addition would be from about
0.5 to about 5.0 parts by weight while the most preferred
range of addition would be from about l.0 to about 3.0
parts by weight.
The chromogenic coating composition can be applied
to a substrate, such as paper or a plastic film by any of
the common paper coating processes as developed above such
as roll, blade coating or by any of the common printing
processes, such as gravure, or flexographic printing. The
rheological properties, particularly the viscosity of the
coating composition, can be adjusted for each type of
application by proper selection of the type and relative
amounts of hot melt suspending media. While the actual
amount of the hot melt coating dispersion applied to the
substrate can vary depending on the particular final pro-
duct desired for purposes of coating paper substrates CB
coat weight of from about 1 pound to about 8 pounds per
3300 square feet of substrate have been found practical.
The preferred range of CB coat weight application is from
about 2.5 pounds to about 5.0 pounds per 3300;square feet
of substrate, while the most preferred range is from about
X ,.
~7~t5-~i
3 pounds to about 4 pounds per 3300 sqaure feet of substrate.
If the CF chromogenic materials and a colour developer (CF)
are combined into a single or self-contained chromogenic
coating composition practical coat weightsinclude from a-
bout 2.0 pounds to about 9.0 pounds per 3300 square feet of
substrate, the preferred coat weight is from about 3.0
pounds to about 6.0 pounds per 3300 square feet, and the
most preferred range is from about 4.0 pounds to about 5~0
pounds per 3300 square feet of substrate.
These hot melt coating dispersions or hot melt
coating compositions, the terms being used interchangeably,
can be set by any cooling means. Preferably a chill roll
is used on the coating apparatus which cools the hot melt
coating immediately after coating, but it is also quite com-
mon to simply allow the coating composition to cool natu-
rally by atmospheric exposure. As the temperature of the
~ coating composition is substantially higher than room tem-
; perature and in light of the fact that the coating thick-
ness is generally less than 50 microns it c~n be seen that
when spread out over a substrate the hot melt material cools
very rapidly. The actual exposure or chill time necessary
for setting of the chromogenic coating composition is depen-
dent on a number of variables, such as coat weight, the
particular hot melt suspending medium used, type of cooling
means, temperature of cooling means and others.
The choice of wall-forming material and hot melt
suspending media is important since certain microcapsules
;~ having walls of hydroxyethylcellulose when made by certain
patented process and certain polyamides tend to agglomerate
even in polar waxes. Agglomeration is undesirable since
this prevents uniform distribution of the chormogenic ma-
terial on the CF sheet. This may adversely affect transfer
and uniformity of the intensity of the formed image.
-23-
.~L~ 7s,t~S
The particular method of encapsulation or the
particular encapsuled chromogenic material are not asser-
ted to be an inventive feature herein. Rather, there are
described in the patent literature various capsular chro-
mogenic materials which may be used. Such chromogens have
been encapsulated in gelatin wall-forming materials (see
U. S. Patents Nos. 2,730,456 and 2,800,457) including gum
arabic, in polyvinyl alcohol, in carboxymethylcellulose,
in resorcinol-formaldehyde wall formers (see U. S. Patent
No. 3,755,190), isocyanate wall-formers (see U. S. Patent
No. 3,914,511) and hydroxypropylcellulose (see U. S. Patent
No. 4,025,455) in addition to mixtures of the above. Micro-
encapsulation has been accomplished by a variety of known
techniques including coacervation, interfacial polymeriza-
tion, polymerization of one or more monomers in an oil,
various melting, dispersing and cooliny methods, and spray
drying methods. Compounds which have been found preferable
for use as wall forming compounds in the various microen-
- capsulation techniques includes: hydroxypropylcellulose,
carboxymethylcellulose, gelatin, melamine-formaldehyde,
polyfunctional isocyanates and prepolymers thereof, poly-
functional acid chlorides, polyamines, polyols, epoxides
and mixtures thereof.
Particularly well suited to use in the present
invention are microcapsules of hydroxypropylcelluselose
(HPC) materials. This is because such microcapsules are
easily dispersed in most hot melt media. If necessary, a
small amount of dispersing agent as described above can
also be added to improve the disperson. In addition, the
HPC capsules have good permeability, strength, and tempe-
rature characteristics.
RADIATION CURABLE SYSTEM
The second preferred coating method of this
X -24-
{D7~
invention involves the use of radiation curable resins.
As with the hot melt activation svstem the radiation cu-
rable resins can be used as either a CF of a CB coating
but preferably are used as the CF coating system. The
basic concept of the radiation curable activation system
involves dissolving a developing agent such as a novolak
resin in a liquid radiation curable material which can be
solidified by exposure to radiation such as ultraviolet
or electron beam. The liquid mixture containing the deve-
loping agent and the liquid radiation curable material isthen applied to a thin film to the continuous web which
is exposed to ultraviolet light to cure the coating.
The radiation curable chromogenic coating compo-
sition useful in the process of this invesntion is essen-
tially a dispersion of a chromogenic material in a liquid
radiation curable substance. The chromogenic material can
be either soluble or insoluble in the liquid radiation
curable substance and the colour developers are preferably
in microencapsulated or dispersed form. Insoluble chromo-
genic colour developers, for use in preparing carbonlessrecord sheets such as the acid clays, are present in the
coating composition as a dispersed particul~te solid. Most
organic colour developers are soluble in the radiation cu-
rable substance of this invention.
The coating composition can contain additional
materials which function as photoinitiators. Addition of
these materials depends upon the particular method of cu-
ring the chromogenic coating. Filler materials can also
be added to modify the properties of the cured film. The
use of non-reactive solvents, which require heat to remove
them during the drying or curing of the coated film, is
avoided.
The chromogenic colour developers most useful in
-25-
~1
7~g5~ii
the radiation curable emhodiment of this invention are the
acidic electron-acceptors and include acid clays such as
attapulgus clay, and silton clay, phenolic materials such
as 2-ethylhexylgallate, 3,5-di-tert-butyl salicylic acid,
phenolic resins of the novolak type and metal modified
phenolic materials such as the zinc salt of 3,5-di-tert-
butyl salicylic acid and the zinc modified novolak type
resins. The most preferred chromogenic colour developers
are the novolaks of p-phenylphenol, p-octylphenol and p-
tert-butylphenol. Mixtures of these colour developers may
be used, if desired. They can be present in the liquid
chromogenic composition in an amount of from about 25% to
a~out 75~ by weight of the chromogenic composition. The
preferred ran~e is from about 35~ to about 65%, and the
most preferred range is from about 40% to about 55%.
The radiation curable substances useful in the
practise of this invention comprises the free radical
polymerizable ethylenically unsaturated organic compounds.
These compounds must contain at least one terminal ethyle-
nic group per molecule. They are liquid and act as dis-
pers~ng media for the chromogenic material and other in-
gredients of the coating composition. They are curable to
a solid resin when exposed to ionizing or ultraviolet radi-
ation. Curing is by polymerization.
A preferred group of radiation curable compounds
are the polyfunctional ethylenically unsaturated organic
compounds which have more than one (two or more) terminal
ethylenic groups per molecule. Due to the polyfunctional
nature of these compounds, they cure under the influence
of radiation by polymerization, including crosslinking, to
form a hard dry tack-free film.
Included in this preferred group of radiation
curable compounds are the polyesters of ethylenically
-26-
~'
~1~3~
unsaturated acids such as acrylic acid and methacrylicacids, and a polydydric alcohol. Examples of some of
these polyfunctional compounds are the polyacrylates or
methacrylates of trimethylolpropane, pentaerythritol, di-
pentaerythritol, ethylene glycol, triethylene glycol, pro-
pyleneglycol, glycerin, sorbitol, enopentylylycol and 1,6-
hexanediol, hydroxy-terminated polyesters, hydroxy-
terminated epoxy resins, and hydroxy-terminated polyure-
thanes and polyphenols such as bisphenol A. An example of
a polyacrylate of a hydroxy-terminated polyurethane found
to be useful in this invention is di(2'-acryloxyethyl)-4-
methylphenylenediurethane.
Also included in this group are polyall~l and
polyvinyl compounds such as diallyl phthalate and tetral-
lyloxyethane, and divinyl adipate, butane divinyl ether
and divinylbenzene. Mixtures of these polyfunctional com-
pounds and their oligomers and prepolymers may be used if
desired.
A second group of radiation curable compounds
are the monofunctional ethylenically unsatured organic
compounds which have one terminal ethylenic group per mole-
cule. Examples o~ such monofunctional compounds are the
C8 to C16 alcohol esters of acrylic and methacrylic acid,
and styrene, substituted styrenes, vinyl acetate, vinyl
ethers and allyl ethers and esters. In general, these
compounds are liquid and have a lower viscosity than the
polyfunctional compounds and thus may be used to reduce
the viscosity of the coating composition to facilitate
coating by any desired method. These compounds are radi-
ation curable and react with the ethylenically unsaturatedpolyfunctional organic compounds during radiation curing
to give a hard drying flexible film. Compounds having only
one terminal ethylenic group may be used alone as the
-27-
7'3~
radiation curable substance. ~Iowever, the resultant radi-
ation cured film may be rather soft and pliable and may be
somewhat too tacky for commercial use. The preferred radi-
ation curable substance is a mixture containing one or
more polyfunctional compounds and one or more monofunctio-
nal compounds. By proper selection of these compounds a
chromogenic coating composition having the desired coating
characteristics for any type of coating application can be
made, and a hard, flexible, tack-free radiation cured film
can be obtained. In general, the most desired films are
obtained by using a radiation curable substance comprising
from about 33~ to about 61~ of the polyfunctional compounds
to about 33~ to about 67% of the monofunctional compounds.
A photoinitiator is preferably added to the
coating compositions if the composition is to be cured by
ultraviolet radiation. A wide variety of photoinitiators
are available which serve well in the system described in
this invention. The preferred photoinitiators are the
benZoin alkyl ethers, such as, Vicure* 30 (a mixture of
alkyl~enzoin ethers manufactured and sold by Stauffer
Chemical Co., Westport, Connecticut), benzoin butyl ether
(Vicure* 10, Stauf~er), benzoin methyl ether, and a,a-
diethoxyacetophenone. Other photoinitiators which have
been used are ~enzophenone,4,4'-bis-(dimethylamino)benzo-
phenone, ferrocene, xanthone, thioxanthane, a,a-azobisiso-
butylnitrile, decabromodiphenyl oxide, pentabromomonchlo-
rocyclohexane, pentachlorobenzene, polychlorinated biphenyls
such as the Arochlor* 1200 series (manufactured and sold
by Monsanto Chemical Co., St. Louis, Missouri), benzoin
ethyl ether,2-ethyl-anthroquinone,l-(chloroethyl)naphtha-
lene, desyl chloride, chlorendic anhydride, naphthalene
sulfonyl chloride and 2-bromoethyl ethyl ether zinc oxide
* Trade Marks
-28-
7~S
combined with a small quantity of water also serves as a
good substitute photoinitiation system. The amount of
photoinitiator added can be from about 0.2% to about 10
by weight of the coating composition, with a preferred
range being from about 3~ to about 8~ by weight.
Photoinitiation synergists can also be added to
the ultraviolet curing coating compositions. Photoiniti-
ation synergists serve to enhance the initiation ef~iciency
of the photoinitiators. The preferred synergists are chain
transfer agents, such as the tertiary alcoholamines and
substituted morpholines, such as triethanolamine, N-methyl-
diethanolamine, N,N-dimethylethanolamine and N-methylmorpho-
line. The amount of photoinitiation synergist added can be
from about 0.2% to about 10~ by weight of the coating com-
position, with a preferred range being from about 3~ to
about 8~ by weight.
Filler materials can be added as flattening
agents, particularly to colour developing coating composi-
tions, to reduce the glossy appearance of the cured resin
films and preserve the appearance of the substrate prior to
coating. Thus a bond paper which has been coated with the
coating composition of this invention and which is then
cured to a solid film gives the impression of being an un-
coated bond paper.
The preferred filler materials are of the colloi-
dally precipitated or fumed silicas. Typical of the silicas
which can he used are the ones trade namedLoVel* 27 (a pre-
cipitated silica manufactured and sold by PPG Industries,
Inc., Pittsburgh, Pennsylvania), Syloid* 72 (a hydrogel
silica manufactured and sold by W.R. Grace & Co., Davisan
Chemical Division, Baltimore, Maryland) and Cab-o-sil* (a
fumed silica manufactured and sold by Cabot Corporation,
* Trade Marks
-29-
1~.37~3S~
Boston, Massachusetts). All of these silicas are known to
gi~e an initial bluish colour with colour precursors such
as crystal violet lactone. However, this colour fades
quickly on aging. Using the record sheet produced by the
process of this invention, the developed colour does not
fade easily. It is theorized that the filler material
through its large surface area provides for increase poro-
sity of the cured resin film, thereby promoting more rapid
and more complete transfer of an oily solution of colour
precursors from a transfer sheet to the record sheet sur-
face. The amount of filler materials can be up to about
15% by weight of the coating composition and the preferred
range is from about 10~ to about 15~ by weight.
Mixing of the ingredients of the coating composi-
tion is not critical. Ingredients can be added one at a
time or they can be added all at once and stirred until
they are uniformly mixed. Good results are obtained when
the ingredients making up the radiation curable substance
and the chromogenic material are heated with stirring to
facilitate blending of these ingredients. If used, the
photoinitiator, photoinitiation synergist and filler are
best added when the coating composition is at or slightly
above room temperature. It is also preferable to add micro-
capsules at room temperature.
The chromogenic compositions can be applied to a
substrate, such as paper or a plastic film by any of the
common paper coating processes such as roll, air knife, or
blade coating, or by any of the common printing processes,
such as offset, gravure, or flexographic printing. The
rheological properties, particularly the viscosity, of the
coating composition, can be adjusted for each type of appli-
cation by proper selection of the type and relative amounts
of liquid radiation curable compounds. While the actual
-30-
11~37~5S
amount of chromogenic coating composition applied to the
substrate can vary depending on the particular final pro-
duct desired, for purposes of coating paper substrates the
practical range of coat weights for the CF chromogenic
coating compositions of this invention are from about 0.2
pounds to about 8 pounds per 3300 square feet of substrate,
thepreferred rangebeing fromaboutO.5 pounds toabout4pounds
per 3300 square feet of substrate and the most preferred
range from about 1.0 pounds to about 3.0 pounds per 3300
1~ square feet of substrate. If the CF and CB chromogenic
materials are combined into a single or self-contained
chromogenic coating compositions practical coat weights
include from about 2.0 to about 9.0 pounds per 3300 square
feet of substrate, the preferred coat weight is from about
3.0 pounds to about 6.0 pounds per 3300 square feet, and
the most preferred range is from about 4.0 pounds to about
5.0 pounds per 3300 square feet of substrate.
These coating compositions can be cured by any
free radical initiated chain propagated addition polymeri-
~ 20 zation reaction of the terminal ethylenic groups of the
-~ radiation curable compounds. These free radicals can be
produced by several different chemical processes including
the thermal or ultraviolet induced degradation of a molecu-
lar species and any form of ionizing radiation utilizing
alpha-particles, beta-rays (high-energy electrons), gamma-
rays,-x-rays and neutrons. The actual exposure time neces-
sary for curing of the chromogenic coating composition is
dependent on a number of variables such as coat weight,
coat thickness, the particular radiation curable substance,
type of radiation, source of radiation, radiation intensity
and distance between the radiation source and the coated
substrate. In most instances curing is virtually instan-
taneous with actual curing times ranging from about 1
-31-
X
7~5
millisecond to about 2.0 seconds. The preferred curing
time is from about 0.1 seconds to about 1.0 seconds, while
the most preferred curing time is from about 0.3 seconds
to about 0.6 seconds.
The preferred curing process is by exposure of
the coating composition to ultraviolet radiation having a
wavelength of about 2000A to about 4000A. For ultra-
violet curing to occur the composition must contain sui-
table ultraviolet absorbing photoinitiators which will pro-
duce polymerization initiating free radicals upon exposureto the radiation source. A typical ultraviolet source
suitable for this type of curing process is a Hanovia 200
watt medium pressure mercury lamp. Curing efficiencies of
the coating composition are dependent on such parameters
as the nature of the radiation curable substance, atmos-
phere in contact with the coating, quantum efficiency of
-'he radiation absorbed, thickness of coating and inhibi-
tory effects of the various materials in the composition.
In the ionizing radiation inducedilcuring of these
coaiing compositions a specific radiation absorbing material
(photoinitiator) is not necessary. Exposure of the coating
composition to a source of high energy electrons results
in the spontaneous curing of the composition to a hard,
tack-free coating. Any of a number of commercially avail-
able high energy ele~tron beam or linear cathode type high
energy electron sources are suitable for curing these com-
positions. Parameters such as the atmospheric environment
and inhibitory effects of the various materials in the com-
position play an important role in the determination of `
the curing efficiency of these compositions.
A particular advantage of the coating step ofthe process of this invention is that it permits the use
of spot coating. Spot coating refers to the fact that less
-32-
~llf37~5
than 100~ of the surface area of the individual sheet
whether it is a CF, CB, self-contained or other sheet need
be coated. For instance, the area of the paper normally
associated with the margin on either side of the printed
side portion need not be coated. This, of course, repre-
sents a significant cost advantage in the savings of encap-
sulated material. The encapsulated material is one of the
most costly materials which goes into the forms manufac-
ture. Therefore by eliminating certain sections of the
web surface that need to be coated a significant cost sa-
vings can be appreciated. The use of spot printing can
vary from simply omitting coating of the margin portion of
the paper to the making of a form wherein only a single
line is actually coated. At the same time, forms such as
computer printouts can be made wherein only every other
line is coated. Thus it can be seen that from about 10% to
about 95% of the surface area of the paper need not be
-~ coated. In most instances it would be most convenient to
simply not print the marginal areas of the paper which
would save from about 10% to about 30~ of the total encap-
sulated material cost.
Upon completion of the coating operation and the
appropriate setting or curing operation the web or sub-
strate is wound onto a mandrel and placed in storage. The
individual roll is held in storage and then combined with
a predetermined number of additional coated or uncoated
webs during the collating operation. For purposes of
this application the term collating shall refer to a step
in the process of this invention whereby a plurality of
individual coated or uncoated webs are arranged in order,
i.e. CB coating next to a C~' coating, e~c. The term colla-
ting means shall be understood to refer to apparatus or
other means for accomplishing the desired arrangement of
-33-
X'
s
the plurality of individual webs.
An adhesive step is completed prior to, duringor after the collating operation. The adhesive material
is applied or the adhesive means are used generally only
after a plurality of the individual webs have been removed
from storage and are being processed, i.e. collated. The
adhesive is applied to one or more edges of the plurality
of individual webs or in the alternative an adhesive can
be applied over all or a portion of the surface of one or
more of the individual webs. Any of the well known glues
or adhesives normally used in the paper industry are usable
in the adhesion means of this invention. Alternate adhesion
methods include bonding members such as adhesive strips,
staples, V-shaped slits and other less commonly encountered
methods. While the adhesion step has been described as
generally occurring after the coating step or steps and
before the collating and finishing steps it can be completed
at any convenient point during the process of this inven-
tion. More particularly, in the most preferred embodiment
of the process of this investion a liquid adhesive is ap-
plied by adhesion means prior to the collating step and the
individual webs are combined during the finishing step.
Thus in the most preferred embodiment an adhesive is applied
prior to collating but the webs themselves are not actually -
placed in combination with one another until the finishing
step. In anothex embodiment of this invention the adhe-
sion means may be omitted altogether and the individual
webs are not necessarily joined to one another but may be
merely arranged in the appropriate sequence with one another.
In still another embodiment of this i~vention the adhesion
means may be located after the collating means in the ope-
rating sequence. In a further embodiment the collated and
finished sheets may be bound or adhered to one another after
-34-
S
the finishing step. The p~rticular sequence and apparatusused in the adhesion means, collating means and finishing
means is a matter of individual choice and is dependent
upon the final product desired. No special significance
is attached to the particular order or occurrence of these
steps.
After, during or prior to the adhesive operation
the continuous substrates are advanced to collating means.
The collating means arrange the various individual webs
into the proper relationship with one another. This can
involve the arrangement of colours if the customer copy or
if the original is white the customer copy is green and
the file copy is red or in the alternative this can involve
the arrangement of particular sheets so that the CB and CF
coated sheets will be in contact when the final form is
made. If self-contained type carbonless paper is used the
coated surface of the paper is the topmost surface of each
sheet. All of this is done by pre-arranged programming
of the collating apparatus.
After collating the forms are finished by any of
a variety of steps. The finishing operation can involve
the steps of attaching the sheets to one another, parti-
tioning the sheets into suitable sizes, stacking the sheets
into appropriate stacks and/or packaging the sheets in
addition to other steps which may be desired.
-35-
