Note: Descriptions are shown in the official language in which they were submitted.
131977~ ~ ;
FIELD OF THE JNVENTION ~
. - .
This invention relates to providing clean sheet ~ -
felting equipment and the like for paper production
and, more particularly, to chemical treatment of
papermill felts and the like to control the deposit of
sticky material thereon.
.
BACKGROVND OF TH~ INVENTION
'
The manufacture of paper tvpically involves the
processing of a carefully prepared aqueous fiher
suspension to produce a highly uniform dry paper sheet.
Three steps included in the typical process are sheet
forming, where the suspension is directed over a porous
mesh or "wire" upon which fibers are deposited while
liquid filters throuqh the wire; sheet pressing, where
the formed sheet is passed through presses covered with
porous "felt" to éxtract retained water from the sheet,
to improve the sheet's uniformity, ~nd to impart
surface quality to sheet; and paper drying, where
residual water is evaporated from the sheet. The sheet
may then be further processed into the finished paper
product.
It is well known that evaporation of water is
energy intensive and thus relatively expensive.
Consequently, efficient papermaking is dependent upon
extracting water during the forming and pressing -
operations, and avoiding sheet defects which render the;~
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1~1977~
dried sheet unfit for use. Felts and wires are thus
particularly important because they affect not only water
removal but, because of their intimate contact with the
sheet, the quality of the sheet itself. Deposits allowed
to collect on the felt or wire can affect its water
removal efficiency, can cause holes in the sheet, and can
be transferred to the sheet material to create defects.
The quality of the aqueous fiber suspension used to
produce the sheet is dependent upon many factors,
including the wood and water used as raw materials, the
composition of any recycled material added to the process,
and the additives used during preparation of the
suspension. Thus a variety of dissolved or suspended
materials can be introduced into the manufacturing
process, including both inorganic materials such as salts
and clays, and materials which are organic in nature such ~ -
as resins or "pitch" from the wood, as well as inks, ~ -
latex, and adhesives from recycled paper products. A
build up of deposits containing inorganic and/or organic
materials on felts and other sheet forming equipment
during the manufacturing process is recognized as a
troublesome obstacle to efficient papermaking.
Particularly troublesome are the sticky materials such as
glues, resins, gums and the like which are associated with
recycled fibers. The terminology "sticky material" as ~ `
used herein, refers to the adherent deposits which form on
pulp and papermaking equipment surfaces and which are
derived or originate from the resinous materials contained
in the wood pulp, i.e. pitch, as well as any synthetic -~
materials derived from recycled fibers such as ink,
adhesives, sizing agents, retention aids, salts, clays and
the like. Sticky material does not include slime or other -
microbiological deposits which tend to form on the static, `
non-moving equipment surfaces in pulp and papermaking
processes.
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1319778
Methods of quickly and effectively removing deposits
from the papermill sheet forming equipment are of great
importance to the industry. The paper machines could be
shut down for cleaning, but ceasing operation for cleaning
is undesirable because of the consequential loss of
productivity. On-line cleaning
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1319778
is thus greatlv prefèrred where it can be effectively
practiced.
~he wir~ belt or cylinder used for sheet forming
cvcles continuously, as a belt, during production. The
sheet-contact portion of the cycle begins where
application of the fiber suspension to the wire belt or
cylinder is started and continues until the formed
sheet is separated from the wire surface; and the
return portlon of the cycle returns the wire from the
position where the formed sheet has been removed from
its surface to the beginning of the sheet-contact
portion. With wire belts such as Fourdrinier wires,
on-line wire cleaning has generally been performed
during the return stage (i.e. where the wire is not in
contact with the forming sheet) by treating the
returning wire with a cleaning liquid (typically
water); often by showering the wire with liquid under
pressure. The showers can be assisted by mechanical
surface cleaniny. Use of water showers, with or
without mechanical assistance, has not proved entirely
satisfactory in preventing a build-up of either organic ~-
compounds or inorganic deposits on the wires, and
additional materials have been used to provide cleaning
liquids which are more effective. Predominantly
fibrous or inorganic materials have been successfully
removed using water-based formulations containing
either acids or alkalis formulated with other chemicals - ~-
such as surfactants. Where organic deposits are ~-
prevalent, they have been removed with some success by
using organic solvents, including some formulations
containing aromatic compounds with low flash points or
chlorinated hydrocarbons. In some machines fine-pored ~ ;
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13~977~
fabric belts are no~ used instea~ of the more
traditional ~ires.
Papermill felts also commonly circulate
continuously in belt-like fashion between a sheet
contact stage and a return stage. During the sheet
contact stage water is drawn from the sheet usually
with the aid of presses and/or vacuum into the pores of
the felt. A clean felt, having fine pores which are
relatively open, is especially desirable for effective
paper manufacture since this allows efficient removal
of water from the paper sheet. A felt cleaning
procedure should remove both organic and inorganic
deposits of both a general and localized nature,
maintain felt porosity, and condition the fabric nap
without chemical or physical attack on the substrate.
Mechanical removal, typically by blade contact, has
been used to remove debris from the felt surface.
However, cleaning liquids are also utilized to remove ;
troublesome build-up of organic and inorganic deposits.
The fabric composition and conformation of many
papermill felts makes them susceptible to chemical
degradation. The cleaning chemicals should be easily ~`
removed by rinsing. Both continuous and shock cleaning ~ - -
is used in most papermills. The chemicals used include ~-
organic solvents, often chlorinated hydrocarbons. Acid
and alkali based systems are also used, but at lower ~-
concentrations than used in wire cleaning. High
concentrations of alkali metal hydroxides are often
unsuitable for felt cleaning as they "attack" the
fabric material.
Some of the more successful organic solvents have
been identified as health risks, such as carcinogens,
and thus require especially careful handling. Other
- 5 -
131 9778
solvent baced products can damage plastic or rubber
components used in the paper forming process. One
on-line treatment of felts which we know has been used
for several years with some success involves contacting
the felt with aqueous solution of cationic surfactants
such as alkyldimethyl benzyl ammonium chloride wherein
the alkvl aroup consists of a mixture of C12H25, C14H29
and C16H33 groups. However, experience has shown that
some sticky materials still tend to adhere to felts
despite treatment with these surfactants. Another felt
conditioning practice which has been advocated in the
past is application of aqueous solutions of cationic
polymers to the felts. However this type of treatment
can actually lead to a build-up of deposit of materials
derived from the cationic polymers themselves
Other sheet forming eauipment such as deckers,
filters, screens, and rolls can also become fouled.
The process problems and treatments are, as a general
rule, similar to the felt system, although certain
considerations such as maintaining porosity and -
avoiding chemical degradation of fabric, which are
important in felt cleaning and cleaning certain other
fine-pored equipment components, may not be so critical
for this other equipment. -
Natural resin or gum in fresh wood can vary,
depending on the species. Some types of pine wood, -
especially those containing 2 weight percent or more of
resin, are commonly used in only very low percentages
due to the gum and resin problems they cause. Paper-
makers alum or sodium aluminate have been traditionally :;
used to control natural wood resin deposits. These
products are added into the total pulp system with the
ob~ective of depositing the resin on the fiber. The
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1319778
effectiveness of thi~ approach is limited by such
factors as pH, the potential for corrosion, paper sheet
formation, and the need to control interaction with -~
other chemicals in the pulp system. Treatments which
would permit the unrestricted use of these problem pine
wood sources could have significant beneficial economic
impact on some pulp and paper producers.
The increasingly more common use of recycled fiber
has contributed to more serious build-ups of sticky
material during paper formation. The glues, resins,
gums, etc. which are found in recycled, secondary fiber
tend to adhere to various parts of the paper-forming -
machine and to resist on-line shower cleaning. The
materials which adhere to the felt can seriously affect
drainage and paper formation. The end result in the
product is holes, and ultimately, in some cases, breaks
in the sheet during paper processing. Frequent
shutdown may be necessary to solvent wash the felt to
remove the particularlv sticky material associated with
recycled fiber. The advantages of paper recycling can
thus be somewhat offset bv reduced productivity of the
papermaking machines.
Certain organic cleaners which were used
frequently in the past have become environmentally
undesirable. Thus, greater need has developed for
cleaners which remove organic deposits without
presenting an environmental hazard. Naturally,
formulations used should not be destructive of the
felts or other sheet forming equipment. While some
materials have been considered to perform
satisfactorily under certain conditions, there is still
a continuing need for more effective deposit control
agents for paper forming, particularly where recycled
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1319778
fiber is used as a raw material.
Another approach to deposit control has been the
use of pulp additi~es such as anionic aryl sulfonic
acid-formaldehyde condensates or cationic
dicyandiamide-formaldehyde condensates. The additives -~
may function for example as sequestrants, dispersing
agents or surface active agents. In particular the
cationic dicyandiamide-formaldehyde aminoplast resins
have been described as bringing about the attachment of
pitch (eg. resinous matter and gums), in the form of
discrete particles, to pulp fibers so that the pitch
particles are uniformly distributed on the fibers
themselves. Consequently, the amount of pitch which
accumulates on the papermaking machine is reportedly
reduced without causing dark spots or specks of pitch
in the paper product.
SUMMARY OF THE INVENTION
We have found that the deposit of sticky material
from papermakin~ pulp onto papermill felts and other
papermaking equipment used in processing a pulp slurry -
into sheets can be inhibited by applying to the ~ -
equipment an aqueous solution containing at least about -
2 ppm of a cationic polymer and applying to the -
equipment an aqueous solution containing compounds ~ -
selected from the group consisting of water-soluble
nonionic and cationic surfactants in an amount
effective to inhibit build-up of deposits derived from
the cationic polymer. Preferably, the aqueous solution
containing the cationic polymer and surfactant is
substantially free of anionic macromolecules.
Preferred cationic polymers include protonated or A
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- 8 - ~-
1319778
quaternary ammonium polymers such as polymers formed by
reacting epih~lohydrins with dimethylamine or
diethylamine. Preferred cationic surfactants include
alkyldimethyl benzyl ammonium chlorides having alkyl
groups with between about l2 and l6 carbon atoms. The
invention is particularly beneficial when used for - -
treating felts and like equipment components used in
processing pulp slurry into sheets.
An object of this invention is to provide a
process which can effectively control the deposit of
material on paper-forming equipment.
Another object of this invention is to provide a
papermill deposit control process which has improved
effectiveness for papermaking with recycled or high
resin pine pulp fiber.
Yet another object of this invention is to provide ~-
a papermill deposit control process which is environ-
mentally acceptable. -
Still another object of this invention is to
provide a means for increasing the productivity and
product quality in papermaking processes.
These and other objects and advantages of the
present invention will become apparent from the
following detailed description of the invention.
-
BRIEF DESCRIPTION OF THE DRAWING
In the drawings:
Fig. l is a schematic side elevation drawing of
felts in a papermaking machine which can be treated in
accordance with the present invention.
Fig. 2 is a schematic side elevation drawing of
felts in a vat forming papermaking machine which can be ;
,:
131~77~ ~ :
treated in accordance with the present invention.
DETAILED DESCRIPTION
'''
The present invention is directed to using aqueous
solutions of certain water-soluble cationic polymers
and certain water-soluble surfactants to substantially
inhibit the deposit of both organic and inorganic
deposits on felts or other sheet forming equipment,
especially other fine-pored components of such
equipment. Treatment, including a cationic polymer in -
combination with a cationic surfactant, provides
surprisingly effective control of deposits on the -
treated equipment, even where recycled fiber represents -
a substantial portion of the pulp formulation. The -
invention provides a particularly effective felt
cleaner and conditioner for paper machines.
The present invention is of general applicability -
as regards the precise nature of the polymer, and a - ~ -
considerable variety of different polymers can be used, ~`
provided that they are cationic. Use of ^
polyethylenimines is considered to be within this -
invention, as is use of various other polymeric
materials containing amino groups such as those
produced in accordance with the procedure disclosed in
U.S. Patent No. 3,250,664, U. S. Patent No. 3,642,572,
U. S. Patent No. 3,893,885 or U. S. Patent No.
4,250,299; but it is generally preferred to use
protonated or quaternary ammonium polymers. These
preferred polymers include polymers obtained by
reaction between an epihalohydrin and one or more
amines, and polymers derived from ethylenically
unsaturated monomers which contain a quaternary
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131977~
am~onium group. The cationic polymers of this invention
also include dicyandiamide-formaldehyde condensates.
Polymers of this type are disclosed in U.S. Patent No.
3,582,461.
Either formic acid or ammonium salts, and
most preferably both formic acid and ammonium chloride,
may also be included as polymerization reactants.
Howe~er, some dicyandiamide-formaldehyde condensates
have a tendency to agglomerate on felts and the like,
even in the presence of cationic surfactants. One
dicyandiamide-formaldehyde type polymer is commercially
available as Tinofix QF from Ciba Geigy Chemical Ltd.
of Ontario, Canada and contains as its active
inaredient about 50 weight percent of a polymer
believed to have a molecular weight between about
20,000 and 50,000.
Among the quaternary ammonium polymers which are
derived from epihalohydrins and various amines are
those obtained by reaction of epichlorohydrin with at
least one amine selected from the group consisting of ;~
dimethylamine, ethylene diamine, and polyalkylene
polyamine. Triethanolamine may also be included in the
reaction. Examples include those polymers obtained by
reaction between a polyalkylene polyamine and
epichlorohydrin, as well as those polymers obtained by
reaction between epichlorohydrin, dimethylamine, and -
either ethylene diamine or a polyalkylene polyamine. A
typical amine which can be employed is N,N,N',N'-tetra-
methylethylene-diamine as well as ethylene diamine used
together with dimethylamine and triethanolamine.
Polymers of this type include those having the formula:
* ~rade-mark -
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1319778
lHCH2C~ ~ IH3 1
HOCH ~CH~;N_CH2_CH_CEI2_--N+ CH2-TH CH2 t - :~
?C~-2 Cl OH _ CH3 OH / 2
where A is from 0-50Q, although, of course, other ~-
amines can be employed. ~ -
~he preferred cationic polymers of this invention
also include those made by reacting dimethylamine, `
diethylamine, or methylethylamine, preferably either ~
dimethylamine or diethvlamine, with an epihalohydrin, ^
preferably epichlorohydrin. Polymers of this type are
disclosed in U.S. Patent No. 3,738,945, and Canadian
Patent No. l,0g6,070.
Such polymers are commercially
available as Agefloc*A-50, Agefloc*A-50~V, and Agefloc*
~-50 from CPS Chemical Co., Inc. of New Jersey, U.S.A.
- These three products reportedly contain as their active -~
ingredients about 50 weight percent of polymers having
molecular weights of about 75,000 to 80,000, about
200,000 to 250,00~, and about 20,000 to 30,000,
respectively. Another commerically available product
of this type is Magnifloc*573C, which is marketed by
American Cyanamide Company of New Jersey, U.S.A. and is
believed to contain as its active ingredient about 50
weight percent of a pol~mer having a molecular weight
of abo~t 20,000 to 30,000.
Typical cationic polymers which can be used in the ~ ~ ~
present invention and which are derived from -
ethylenically unsaturated monomeræ include homo- and
co-polymers of vinyl compounds such as vinyl pyridine ~-
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1319778
and vinyl imidazole which may be quaternized with, say,
a Cl to C18 alkvl halide, a benzyl halide, especially a
chloride, or dimethyl or diethyl sulphate, or vinyl
benzyl chloride which may be quaternized with, say, a
tertiary amine of formula NRlR2R3 in which Rl, R2 and
R3 are independently lower alkyl, typically of 1 to 4
carbon atoms, such that one of Rl, R2, and R3 can be C
to C18 alkyl; allyl compounds such as diallyldimethyl
ammonium chloride; or acrylic derivatives such as
dialkyl aminomethyl(meth)acrylamide which may be
quaternized with, say, a Cl to C18 alkyl halide, a ..
benzyl halide or dimethyl or diethyl sulphate, a : :
melhacrvlamido propyl tri(Cl to C4 alkyl, especially
methyl) ammonium salt, or a (meth)acryloy-loxyethyl
tri(Cl to C~ alkyl, especially methyl) ammonium salt,
said salt being a halide, especially a chloride,
methosulphate, ethosulphate, or l/n of an n-valent
anion. These monomers may be copolymerized with a
(meth)acrylic derivative such a acrylamide, an acrylate ~ :.
or methacrylate Cl-Cl8 alkyl ester or acrylonitrile or
an alkyl vinyl ether, vinyl pyrrolidone, or vinyl
acetate. Typical such polymers contain 10-100 mol % of ~ .
recurring units of the formula~
P~l
I R3
CH2 - '' C
,
COO(CH2)2l ~+ R4
R5 .
- 13 -
1 3 ~ 9 7 7 8 -
and 0-90 mol ~ of recurring units of the formula~
CH2 C~
in which Rl represents hydrogen or a lower alkyl
radical, typically of 1-4 carbon atoms, R2 represents a -
long chain alkyl group, typically of 8 to 18 carbon
atoms, R3, R4, and R5 independently represent hydrogen : -
or a lower alkyl group while X represents an anion, 'A',' '
typically a halide ion, a methosulfate ion, an
ethosulfate ion. .:
Other quaternary ammonium polymers derived from an
unsaturated monomer include the homo-polymer of. ~
diallyldimethyl ammoniu~ chloride which possesses :
recurring units of the formula: ~ -
~ 2
-CH CH CH2 ~
C~2 CH2 ~ : '
N ~ - :
C~3 C 3 . - :
In this respect, it should be noted that this polymer :
should be regarded as "substantially linear" since .
although it contains cyclic groupings, these groupings
are connected along a linear chain and there is no
crosslinkin~. :
Other polymers which can be used and which are
derived from unsaturated monomers include those having :
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1319778
the formul~:
_ _ ~.
+ +
Y - - ZNR'R" - Z'NR'R" - - Z-Y'
X X n - :
where Z and Z' which may be the same or different is
-CH2CH=CHCH2- or -CH2-CHOHCH2-, Y and Y', which may be
the same or different, are either X or -NR'R", X is a
halogen of atomic weight greater that 30, n is an
integer of from 2 to 20, and R' and R" (i) may be the
same or different alkyl groups of from 1 to 18 carbon
atoms optionally substituted by l to 2 hydroxyl groups;
or (ii) when taken together with N represent a
saturated or unsaturated ring of from 5 to 7 atoms; or
(iii) when taken together with N and an oxygen atom ...
represent the N-morpholino group. A particularly
preferred such polymer is poly(dimethylbutenyl)
ammonium chloride bis-(triethanol ammonium chloride). :
Another class of polymer which can be used and .
which is derived from ethylenically unsaturated
monomers includes polybutadienes which have been ..
reacted with a lower alkyl amine and some of the .. :
resulting dialkyl amino groups are quaterniæed. In :
general, therefore, the polymer will possess recurring :
units of the formula: ~
a) -(CH2-CH)- b) -(CH2-CIH)- c) -(CH2-CH)- and d) -(CH2-CIH)- -
~H IH2 CH2 1 2
ll C~2 IH2 CH3 :
CH2 +CIH2 ~ 2
NR3 X NR2
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- 15 - :. ~
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1319778
in the molar proportions a:b1:b2:c, respectively, where R
represents a lower alkyl radica], typically a methyl or --
ethyl radica]. It should be understood that the lower
alkyl radicals need not all be the same. Typical
quaternizing agents include methyl chloride, dimethyl
sulfate, and diethyl sulfate. Varying ratios of
a:b1:b2:c may be used with the amine amounts (b1 + b2)
being generally from 10-90% with (a + c) being from
90%-10%. These polymers can be obtained by reacting -
polybutadiene with carbon monoxide and hydrogen in the
presence of an appropriate lower alkyl amine. ~-
Other cationic polymers which are capable of
interacting with anionic macromolecules and/or sticky
material in papermaking pulp may also be used within :
lS the scope of this invention. These are considered to
include cationic tannin derivatives, such as those -
obtained by a Mannich-type reaction of tannin (a
condensed polyphenolic body) with formaldehyde and an
amine, formed as a salt, eg. acetate, formate,
hydrochloride or quaternized, as well as polyamine
polymers which have been crosslinked, such as
polyamideamine/polyethylene polyamine copolymers
crosslinked with, say, epichlorohydrin. Natural gums
and starches which are modified to include cationic
groups are also considered useful.
The molecular weight of the most useful polymers
of this invention is generally between about 2,000 and
about 3,000,000, although polymers having molecular
weights below 2,000 and above 3,000,000 may also be used
with some success. Preferably the molecular weight of the
polymer used is at least about 10,000, and is most
preferably at least about 20,000. Preferably the
molecular weight of the polymer used is about 300,000 or
" . ,
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131~778
less, and is most preferably about 50,000 or less. The
polymers most preferably have a molecular weight within
the range of about 20,000 to about 50,000. Mixtures of
these polymers may also be used.
The present invention is also of general
applicability as regards the precise nature of nonionic
and cationic surfactants which may be used, and a
considerable variety of different surfactants can be used
in combination with the polymer component, provided that
they are water soluble. Suitable nonionic surfactants -
include condensation products of ethylene oxide with a
hydrophobic molecule such as, for example, higher fatty
alcohols, higher fatty acids, alkylphenols, polyethylene
glvcol, esters of long chain fatty acids, polyhydric
alcohols and their partial fatty acid esters, and long
chain polyglycol partially esterfied or etherified. A
combination of these condensation products may also be
used.
Cationic surfactants are generally preferred.
Particularly preferred cationic surfactants suitable
for use in this invention include water soluble
surfactants having molecular weights between about 200 --
and 800 and having the general formula
R ~ R
r~ x : :- ' '
R ~ ~ R
wherein each R is independently selected from the group
consisting of hydrogen, polyethylene oxide groups,
polypropylene oxide groups, alkyl groups having between
about 1 and 22 carbon atoms, aryl groups, and aralkyl
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131977~
groups, at least one of said R groups being an alkyl
group having at least about 8 carbon atoms and
preferably an n-alkyl group having between about 12 and
16 carbon atoms; and wherein X is an anion, typically
5_ a halide ion (e.g. chloride). Mixtures of these
compounds can also be used a~ the ~urfactant of this
invention.
Preferably two of the R groups of the cationic
~urfactants of the formula are selected from the group
consisting of methyl and ethy], and are most preferably
methyl; and preferably one R group is selected from the
aralkyl groups ~ -C~2- and
~ -CH2-CH2-, and is most preferably benzyl.
Particularly useful surfactants thus include alkyl
dimethy~ benzyl ammonium chlorides having alkyl groups ;
with between about 12 and 16 carbon atoms. One
commercially available product of this type includes a
mixture of alkyl dimethyl benzyl ammonium chlorides
wherein about ~n~i of the surfactant has a C14~29
n-alkyl group, a~out 40~ of the surfactant has a C12H25
n-alkyl group, and about 10~ of the surfactant has a ~-
C16H33 n-alkyl group. This product is known for its
microbicidal effectiveness.
The surfactants considered suitable for use in
this invention also include the group of
pseudo-cationic materials having a molecular weight
between about 1,000 and about 26,000 and having the
general formula NRlR2R3, wherein Rl and R2 are
polyethers such as polyethylene oxide, polypropylene
oxide or a combined chain of ethylene oxide and
propylene oxide, and wherein R3 is selected from the
group consisting of polyethers, alkyl groups, or -
- 18 -
1319778
hydrogen. Example~ of this type of surfactant are
disclosed in U. S. Patent No. 2,979,528.
We have found that when the cationic polymers of
this invention are applied together with the nonionic
and/or cationic surfactant to felts, the felts resist
the build-up of sticky deposits. In particular, the
adhesion of sticky material associated with recycled
fiber is effectively controlled. Thus, the invention
is particularly advantageous for papermaking systems
employing a substantial proportion, say, at least about
10%, recycled fiber. Moreover, outstanding results have
been obtained in svstems wherein recycled material accounts
for at least 70~ of the fibers, and even for systems when
the papermill pulp fibers are derived about 100~ from
recycled material. The invention is also considered
particularly advantageous for controlling resin deposit
from fiber, substantially derived (say, 5% or more) from
pine wood containing greater than two weight percent or ~-~
more resin.
While the mechanism of this phenomenon is ~ot
completely understood, it is well known that adhesive ~;
materials associated with recycled fiber are generally
hydrophobic, and it is believed that the products
formed after interaction of those hydrophobic materials -;
with the cationic components of this invention more
readily associate with water. The wetted adhesive
materials may thus substantially lose their tendency to
adhere to the underlying felt surface so that they can
be easily removed from the felts. It is also known
that papermaking pulp contains colloidal materials and ~ -
anionic macromolecules, including synthetic anionic
macromolecules which might be added as part of the
papermaking process as well as those natural anionic
-- 19 -- . ..
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1319778 :~
polymers, resins, soaps, surfactants and organic acids
(e.g. abietic acid) which ha~e become associated in the
industry with "anionic trash". It is believed that the
cationic components applied in accordance with this
invention may interact with the anionic macromolecules
and colloidal particles to form products which can be
easily removed from felts. In any case, the tendency
of adhesive material to pass by papermaking equipment
rather than adhering to it, is greatly increased by
treatment in accordance with this invention.
The cationic polymers and the surfactants of this
invention are applied in aqueous solution directly to the
equipment being treated. A treatment with the surfactant ~-~
alone has not provided the degree of deposit control which
can be obtained by the combinations of this invention. On
the other hand, over-application of polymer to papermill
felt, without sufficient surfactant will result in a
build-up of deposits derived from the polymer itself and
thus, in the case of felts, in reduced porosity which can
eventually retard water removal or otherwise effect
production (e.g. hy increasing tackiness). Thus, the
treatment dosage of polymer and surfactant should generally
be adjusted to the demands of the particular system being
treated. Preferably, the aqueous solution containing the
cationic polymer and the surfactant should be substantially
free of anionic macromolecules. These anionic materials
include natural materials such as wood lignins, byproducts
of chemical pulping such as sodium lignosulfonates, and
synthetic materials such as polyacrylates.
The polymers and surfactants of this invention are
typically supplied as liquid compositions comprising
aqueous solutions of the polymer and/or surfactant.
Polymer concentrations in the compGsitions may range
- 20 -
13~778
f~om the relativelv dilute solutions having polymer
concentrations suitable for continuous application, up
to the solubility or gelling limits of the polymer, but
generally the compositions are relatively concentrated
for practical shipping and handling purposes. Indeed,
the liquid compositions may comprise additional
materials which further the dissolution of the polymers
so as to allow more concentrated compositions. An
example of these materials are alkoxyethanols such as
butoxyethanol. Aqueous compositions suitable for shipping
and handling will generally contain between 5 and 50 weight
percent, active, of the cationic polymer of this invention. ~-
While the cationic surfactants of this invention may be ;~
supplied as compositions separate from the polymer
compositions and then either applied to the felts
separatelv (e.g. by using separate shower systems) or mixed
prior to application, it is preferred to provide aqueous
compositions comprising the cationic surfactant as well as
the cationic polymer. While other agents may also be
present in the compositions of this invention, useful
compositions may be provided in accordance with this
invention which contain a pitch control agent consisting
essentially of the above-described cationic surfactants and
cationic polymers. In general, aqueous compositions
suitable for shipping and handling will contain between 5
and 50 weight percent total of the polymer and surfactant
components. The weight ratio of surfactant to polymer in
such combined compositions is generally between about 50:1
and l:S0. Preferably the weight ratio of surfactant to
polymer in the aqueous composition is between about lO:l
and about l:l, especially where oils may potentially be
present; and is most preferably about l:l for general
application, although excess surfactant (e.g. a weight
: ': ' ,, '-
,':.., :
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-.
- 21 -
~ :,
1319778
ratio of 1.1:1, or more) may be considered most suitable in
the event oils might be present.
One aqueous formulation considered particularly
suitable for separate application of the polymer
component in con~unction with additional application of
the surfactant is available commercially from Dearborn
Chemical Co., Ltd. of Ontario, Canada and comprises
about 17 weight percent, active, of a polymeric
condensation product of formaldehyde, ammonium
chloride, dicyandiamide and formic acid which has a
molecular weight believed to be about 20,00Q to 50,000,
about 2 weight percent, active, of a polymer derived by
reacting epichlorohydrin with dimethylamine which has a
molecular weight believed to be about 20,000 to 30,000,
and ahout 8 weight percent of butoxyethanol. Lesser
amounts of other materials, including about 0.4% active
of an alkyldimetny~ benzyl ammonium cnloride surfactant
containing the mixture of C12, C14 and C16 n-alkyl
substituents described above are also present in said
product, but are not considered essential to its
utility for separate addition. In particular the
relative amount of alkyldimethyl benzyl ammonium chloride
surfactant in this product is considered insufficient
to activate the polymer deposit inhibiting effect of
this invention. Another aqueous formulation considered
particularly suitable for separate addition of the
polymer, also available commercially from Dearborn
Chemical Co., Ltd., comprises about 17 weight percent,
active, of a poly(hydroxyalkylene dimethyl ammonium
chloride) having a molecular weight of about 20,000.
An aqueous formulation considered particularly suitable
for separate addition of the surfactant to this
invention, also available commercially from Dearborn
..
;'' ;-~" ~:
- 22 -
1319778
Chemical Co., Ltd., comprises about 16~ active of the
alkyldimethyl benzyl ammonium chloride surfactant mixture
described above.
The most appropriate treatment dosage depends on ~-
such system factors as the nature of the adhesive
material, and whether cleaning is continuous or
periodic. Even liquid compositions comprising
relatively high concentrations of a polymer of the
invention (for example, 50%) may be employed at full
strength (100% as the liquid composition), for example
by spraying the undiluted ]iquid composition directly onto
the felts. However, particularly where continuous
treatment is practiced, the compositions may be
advantageously diluted at the treatment location with
clean fresh water or other aqueous liquid. Where
necessary for water economy, a good quality process
water may be adequate for dilution.
The advantages of this invention can be realized
at application concentrations as low as 2 ppm of the
polymer, especially where continuous treatment is
practiced, and, as explained further below, sufficient
surfactant to inhibit a build-up of deposits derived
from the applied cationic polymer component.
"Continuous treatment" of felt as used herein means
that the felt is routinely treated at least once during ;
the cycle between its sheet contact stage and its
return stage. This routine treatment is most
advantageously applied during the early portion of -
return stage. The felt can then be contacted with the
sheet such that even the sticky material, including ~-
that typically associated with recycled fibers, is
inhibited from adhereing to the felt, and that material
which does deposit is more readily washed away when
:~ '
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- 23 - ~
~, ,'' -
1319778
aqueous wash solution is applied during the return
stage. In some cases, continuous treatment is not
practical and treatment with the cationic polymers and -
surfactants of this invention may be periodic. For
example, aqueous solutions of the polymer and
surfactant may be sprayed on the felt until the felt is
satisfactorily conditioned and the spray may then be
discontinued until supplemental conditioning is needed
to further inhibit the build-up of deposits on the
felt.
Treatment procedures are more specifically
described by reference to the model papermaking felt
systems schematically represented in simplified form in
Figures 1 and 2. The press felt system represented
generally as (10) in Fig. 1 comprises a top press felt
(12), a bottom press felt (14) a final press bottom
felt (16) and final press top felt (18). Final press
bottom felt (16) is shown wound about a series of rolls
(20), (21), (22), (23), (24), (25), and (26) and press
roll (29); bottom press felt (14), is shown wound about
a series of rolls (30), (31), (32), (33), (34), (35)
and (36) and press rolls (37) and (38); top press felt
(12) is shown wound about a series of rolls (40), (41),
(42), (43), (44) and (45) and press roll (47) and -
final press top felt is shown wound about the press
roll 49 and a series of rolls (60), (61), (62) and
(63). Both top press felt (12) and bottom press felt
(14) pass between press rolls (37) and (47). Bottom
press felt (14) passes between press rolls (38) and ~:
~48); and both final bottom press felt (16) and final
press top felt (18) pass between press rolls (29) and
(49). Showers for washing the top press felt (12), the
bottom press felt (14), the final press bottom felt
- 24 -
','"~'.
1319778
(16) and the final press top felt (18) are respectively
shown at (50), (51), (52) and (53). A sheet support
roll is shown at (55). Press (57) comprises press
rolls (37) and (47); press (58) comprises press rolls ~ -
(38) and (48); and press (59) comprises press rolls
(29) and (49).
The press felt system (10) is shown in Fig. 1
positioned to receive sheet material from a Fourdrinier
wire-type machine represented only partially by (64) in
Fig. l, wherein a wire (65) is designed to receive an
aqueous paper stock from a head box (not shown).
Liquid then filters through openings in the wire as the
wire travels during its sheet contact stage to a lump
breaker roll (66) and a couch roll (67) which are generally
provided to physically compress the sheet material and
remove it from the wire (65). The wire (65) then passes
over the head roll (68) and returns to receive additional ~
paper stock. The return is typically directed past a ~-
series of showers (not shown), and wash rolls such as that
shown at (69). Other showers (not shown), may be provided -
for particular components of the system, such as the lump
broken roll (66) or the head roll (68).
During operation of the felt system shown in Fig.
1, sheet material removed from the wire (65) after
couch rol] (67) is directed between rolls (45) and (36)
and pressed between the top press felt (12) and the
bottom press felt (14) by press rolls (37) and (47) of `~
press (57). The sheet material then travels along with
bottom press felt (14) to press (58) where it is
pressed betwen the bottom press felt and press roll
(48) using press roll (38). The sheet material is then
removed from the bottom press felt (14) and travels
on to press (59) where it is pressed between the final
:, ~ --
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- 25 -
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~31~778
press bottom felt (16) and the final press top felt
(18) by press rolls (29) and (49) of press t59). The
sheet material is then removed from the final press
felt (16) and travels over support roll (55) and on to
further processing eguipment such as dryers (not
shown). In the press felt system (10) as shown in Fig.
1, the sheet contact stage of the top press felt (12)
lasts from roll (45) or some point between roll (45)
and press (57) until some point after press (57); the
sheet contact stage of the bottom press felt (14) lasts
from some point between roll (36) and press (57) until
some point after press (58); the sheet contact stage of
final press bottom felt (16) lasts from roll (26) until
some point after press (59); and the sheet contact stage of
final press top felt (18) lasts from some point between
roll (63~ and press (59) until some point after press (59).
It will be evident that additional equipment such
as various presses, rolls, showers, guides, vacuum
devices, and tension devices may be included within the -
felt system 10. In particular wringer presses for
pressing moisture from the felts themselves may be
provided. ~oreover some of the equipment shown such as -
press (58) and final press top felt (18) may be omitted
from a felt system. It will be further evident to one
of ordinary skill in the art that felt systems are -
highly variable both with regard to the number of felts
used and the design of the felt cycling systems.
Felt systems are also used in conjunction with
papermaking processes which do not employ Fourdrinier
wire formers. One such alternate system, which is
especially useful for producing heavier sheet material,
uses vat formers. The initial stages of a vat forming -
system are represented generally in Fig. 2. The system
- 26 -
-
131977~ ::
(7Q) comprises a series of wire cylinders (i.e. vats)
such as those shown at (72) and (73) which rotate so
that a portion of the cylinder is brought into contact
with the pulp slurry and is then rotated to deposit a
layer of paper web onto a bottom couch felt (75). In
addition to the bottom couch felt (75) the system (70)
comprises a first top couch felt (76) and a second top
couch felt (77). Couch rolls (78) and (79) are
provided to aid in the transfer of sheet material from
the vats (72) and (73) respectively onto the bottom
couch felt (75). The bottom couch felt (75) is shown
wound about couch rolls (78) and (79), roll (80), -~
suction drum (81) and press rolls (83), (84), (85) and
(86). The first top couch felt is shown wound about rolls
(88), (89) and (9Q) and suction drum couch roll (91); and
the second top couch felt is shown wound about press rolls
(93), (94), (95) and (96) and rolls (97), (98), (99) and -
(100). Both the bottom couch felt (75) and the first top ~ ~s
couch felt (76) pass between the suction drum (81) and the ~- -
suction drum couch roll (91) which vacuum water from the -
felts and fiber web. Both the bottom couch felt (75) and -
the second top couch felt (77) pass between press rolls
(83) and (93), between press rolls (84) and (94), between ~
press rolls (85) and (95), and between press rolls (86) and -
(96). Press (103) comprises press rolls (83) and (93); ~ -
press (104) comprises press rolls (84) and (94); press
(105) comprises press rolls (85) and (95); and press (106)
comprises press rolls (86) and (96).
Showers for washing the bottom couch felt (75),
the first top couch felt (76) and the second top couch -
felt (77) are respectively shown at (107), (108) and
( 1 09 ) . - -
During operation of the felts shown in Fig. 2, ~
' ' ' ''''
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- 27 - -
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1319778
sheet material r~moved from the vats (72) ana (73)
travels on th~ bottom couch felt (75) over the suction
drum and is pressed between the bottom couch felt and
the second top couch felt (77) by each of the presses
(]03), (104), (105) and (106). The sheet material is
then separated from the couch felts (75) and (77) and
is directed onto further processing equipment such as
the felt system (10) shown in Fig. 1. In the system
shown in Fig. 2 the sheet contact stage of the bottom
couch felt (75) lasts from the vat (72) until just -
after press roller (86); the sheet contact stage of the ~ -
first top couch felt is at the suction drum couch roll;
and the sheet contact state of the second top couch felt
lasts from about roll (100) to until just after press
roller (96). It will be evident that additional equipment
such as vats, presses, rolls, showers, guides, vacuum
*evices, and tension devices may be included within the
system (70). Moreover some of the equipment shown may be
omitted from a vat forming system. It will be fairly
evident to one of ordinary skill in the art that vat
forming systems are highly variable both with regard to the
number of felts used and the design of the felt cycling
systems.
Each felt (12), (14), (16), (18), (75), (76) and
(77) of the systems illustrated in Figs. 1 and 2 can be
continuously treated in accordance with this invention
by applying an aqueous solution of suitable cationic
polymer and surfactant to the felt anywhere along its
return stage (i.e. from the point the felt is separated
from contact with sheet material to the point it is
again brought into contact with sheet material). ~
Preferably the solution is sprayed onto the felt early -
in its return stage, so that adhesive material ~
"'.'" ' '.'
.
, ~,
- 28 -
:,
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.:,-' - -
1319778
transferred from the sheet material to the felt can be
auickly treated. However, the treatment location is
often restricted by felt system design. Thus, showers
such as shown at (501, (51), (52), (53), (107), (108) -
and (l09) in Figs. l and 2 may be used for treatment
purposes. In cases where the applied solution is of a
hiqher concentration than needed for continuous
treatment, the application can be interrupted and then
resumed as needed. For example, where a shower such as
those shown at (50), (51), (52), (53), (107), (108) and
(l09) is used to apply the solution, it may be
intermittently activated and turned off according to -
the demands of the system. Equipment other than felts may
be similarly treated in a manner compatible with their
process operation. ~
For typical papermaking processes, particularly ~- -
those using substantial amounts of recycled fiber, the -
cationic polymer is generally applied at a rate at
least about 0.002 grams per square meter of felt per
minute (g/m2-min), preferably about 0.0l g/m2-min or
more where continuous treatment is used, and preferably
about 0.02 g/m2-min or more during the application
period where application is intermittent. Preferably
polymer application rates of 0.5 grams per square meter -~ `
per minute or less are used to minimize the potential
for felt plugging. Thus, for standard papermaking
machines with felt widths of 2 to 7 meters and felt
lengths of ln to 40 meters, the application rate is
commonly between about 0.02 and 20 grams of polymer per :
minute per meter width (i.e. g/m-min), more commonly - -
between about 0.05 and 12.5 g/m-min. One technique
involves applying 1 g/m-min or more initially, until
the felt is conditioned. Once conditioning has been
', .:
- 29 - ~
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:: .
1319778
accomplished, maintenance polymer application rates may -
be lower, or as explained above, application may even
be discontinued periodically. The surfactant is
applied to felts at a rate effective to inhibit
build-up of deposits derived from the applied polymer
and thus, is important in controlling felt plugging.
Accordingly the weight ratio of surfactant to polymer
is generally kept between about 50:1 and 1:50.
Preferably, in order to provide sufficient surfactant
to control the build-up of deposits derived from the
polymer and to offer protection from incidental amounts
of dirt and oily materials from the pulp the weight -
ratio of surfactant to polymer is about 1:1 or more;
and in order to avoid applying excessive surfactant, the
weight ratio of surfactant to polymer is preferably about
10:1 or less. Most preferably the ratio of the two
components is about 1:1. In any case, we prefer to apply
the surfactant at a concentration of at least about 1 ppm.
Other equipment such as wires, screens, filters, rolls, and
suction boxes, and materials such as metals, granite,
rubber, and ceramics may also be advantageously treated in
accordance with this invention. However, the invention is
particularly useful in connection with treating felts and
like equipment components with pores suitable for having
water drawn therein (i.e. relatively fine pores) where the
build-up of substantial deposits derived from the polymer -
is undesirable; as opposed for example to other equipment ~ -
such as metal and plastic wires having relatively large
pores for draining water therethrough, where a certain
amount of deposit build-up is not considered to create
undesirable problems.
In any case, the concentration of cationic polymer
in the aqueous solution ultimately applied to the felt -
, '
- 30 -
1319778
or other papermaking e~uipment should be at least about
0.0002 weiaht pexcent. Preferably, in order to enhance
the uniformity of distribution of the polymer,
continuous treatment of felt through a felt shower
svstem in accordance with this invention will be
conducted with an aqueous shower solution having
between about 0.0002 weight percent and about 0.02
weight percent of cationic polymer.
Practice of the invention will become further
apparent from the following non-limiting examples. - ~-
:.
EXAMPLE I
: . .
The test of this example was made on a papermaking
machine having a Fourdrinier wire former. The machine -~
had a top first press felt, a bottom first press felt, ~- -
a top second press felt, and a bottom second press felt -
somewhat analagous to the top press felt (12), bottom press -~-
felt (14), final press top felt (18), and final press
bottom felt (16) shown in Fig. l respectively. Each of the
felts had showers. The first press felts received sheet -
material from a Fourdrinier wire situated somewhat
. . .:::.
analagously to the unit (64) shown in Fig. l, and produced ~ ;
corrugated media from stock having about 20% secondary
(recycle) fiber and about 80% hardwood virgin fiber.
The sheet material formed on the wire was
separated therefrom and directed to a first press -
somewhat analagous to the press (57) in Fig. l where it
was pressed between the top first press felt and the
bottom first press felt. The sheet was in turn ;
separated from the first press felts and directed to a -
second press somewhat analagous to the press (59) in -
Fig. l where it was pressed between the top second -
-, ~
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- 31 -
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1319778
~ress felt and the bottom second press felt.
The mlll had previously been experiencing deposit
~uild-up on press felts, particularly on the top second
press felt. The deposits were attributable to pitch
and sticky material originating from the pulp and
recvcled material and picked up from the fiber web
contacting the felts. Sheet breaks at the second press
had been a continuing problem, sometimes occurring as
frequently as once per eight-hour shift. Periodic
shutdown~ were thus necessary to reduce the number of
sheet breaks. The top second press felt was
approximately 20 feet wide and 61.5 feet long (i.e. the
top second press felt had a treatment area of about
114.3 m2).
The top second press felt was treated in
accordance with this invention hy mixing into the
shower water of an existing high pressure shower situated
somewhat analagously to shower (53) in Fig. 1 a test
product containing approximately 7.5~ by weight of the --,'
alkyldimethyl benzyl ammonium chloride mixture described
above which contains C12, C14 and C16 n-alkyl substituents,
and approximately 7.5% by weight of a polymer having a ,
molecular weight of about 20,000 and derived from
dimethylamine and epichlorohydrin, and about 85~ solvent
(the solvent consisted principally of water with minor
amounts of any incidental materials such as ethanol which
were intermixed in the commercial supply of the surfactant ;
and/or polymer). The initial dosage was about 0.06
g/min/m2 of each componenent, and the dosage was
subsequently reduced after four hours to about 0.02 to 0.03
g!min/m2 . ,,
The efficacy of the treatment was monitored by a
Huyck & Smith porosity tester and by the number of
- 32 - '
' ~',"
:'':,.'
1319778
breaks occurring in the second press section. The
porosity of the felt is considered a measure of its
capacity to absorb water from the sheet. A felt with ~-
high porosity (i.e. more open pores) is considered
desirable for sheet dewatering.
The relati~e porosity of the top second press felt was -
monitored over the 21-day trial by using the Huyck & Smith
procedure which provides relative porosity numbers (H.S. `-
Nos.) ranqing from a high of 100% for non-porous or plugged
felts to lower percentages for more porous felts. The H.S.
No. for the top second press felt was maintained at about -
35~i for the first several days of the test. Feed of the -
treatment product was inadvertently interrupted for over 24
hours. An increase of the H.S. No. to about 50~ was
observed and was attributed to this interruption in
treatment. The felt was cleaned and the test was
resumed. Following resumption of treatment the H.S.
No. decreased to about 45% where it was maintained for -
several days. The dosage of each treatment component was
then reduced by about half due to pump malfunction, and an
increase in H.S. No. to 53% was observed. The dosage was
returned to its prior level and the H.S. No. was maintained
at about 53% for the duration of the test.
The porosity measurements made during the test -
showed that where the polymer and surfactant were
applied in accordance with this invention, the
porosity of the felt could be maintained. When the -;
feed was interrupted, felt plugging increased by
approximately 15 to 40 percent. In addition, sheet
breaks caused by the top second press felt were
eliminated for the entire 30-day trial period.
Accordingly it was concluded that treatment in
accordance with this invention prevented breaks and
- 33 - ~ ~
~. ' :-.: -:
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.~. :
131977~
shut-downs attributable to deposits at the second
press; that the treatment prevented adherents
accumulation on the treated felt; and that felt
plugging by fibres was significantly reduced during
treatment.
EXAMPI,E II
The test of this example was made on a vat former
type (rather than Fourdrinier~ papermaking machine.
The machine had a primary bottom felt, a suction drum
couch felt and a primary top felt somewhat analagous to
the bottom couch felt (75), the first top couch felt
(76) and the second top couch felt (77) shown in Fig.
2, respectively. The machine also had a secondary top
felt, a secondary bottom felt and a final felt somewhat
analagous to the top press felt (12), bottom press felt
(14) and final press bottom felt (16) shown in Fig. 1, --
respectively. (i.e. there was no felt analagous to the
final press top felt (18).) Each of the felts had wash
showers. The machine had 7 wire cylinders (i.e. vats)
situated in series somewhat analagously to the two vats
(72) and (73) shown in Fig. 2, and produced board (e.g.
straw board, tube stock, chipboard or chipboard
partition) from 100% recycle furnish.
The paper web formed on the cylinders separated
from the cylinders and adhered to the underside of a
primary bottom felt. While on the primary bottom felt
the sheet was pressed between the primary bottom felt ;
and an suction drum couch felt and then was directed
through about four other presses between the primary
bottom felt and a primary top felt. The sheet was then
separated from the primary bottom felt and directed to
a secondary press, somewhat analagous to press (57) in
- 34 -
,"-'-.'
- -. . :-
1 3 1 9 7 7 8
Fig. 1, wh~re it was pressed between the secondary top
felt and the secondar~ bottom felt. The sheet was in -;
turn separated from the secondary press felts and - ~ -
directed to the final felt where it was pressed again
at a press somewhat analagous to press (59) in Fig. l
using a top press roll without a felt.
Prior to testing the combination of cationic
polymer and cationic surfactant of the instant
invention, the primary bottom felt, the suction drum ;~
couch felt, the primary top felt and the secondary
top felt were pretreated in a conventional manner with
alkyldimethyl benzyl ammonium chloride product
containing the mixture of C12 C14 and Cl6 n-alkyl
substituents described above, using showers situated
somewhat analagously to showers (107), (108), (109) and
(50) respectively in Figs 1 and 2. In the test, a test
product containing approximately 7.5% by weight of the
alkyldimethyl benzyl ammonium chloride mixture, 7.5% by
weight of a polymer having a molecular weight of about
20,000 and derived from dimethylamine and epichlorohydrin,
and about 85% by weight solvent (i.e. the same product that
was used in Example I) was diluted in the shower water to
an estimated concentration of about 2.6 ppm each of
surfactant and polymer and applied to the same four felts. :
After the felts had shown no plugging as a result of
polymer addition during the initial application period, the
concentrations of the surfactant and polymer were each
raised 50% (to an estimated level of about 4 ppm). The
treatment was continued at this level for the remainder
of the test run. Each of the components was applied to
each felt at a rate of about 1.5 gramstminute during
the initial portion of the test and about 2.25
grams/minute during the remainder of the test. The
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- 35 - - ~
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~319778
primar~ bottom fe]t, the suctlon drum couch felt, the
primarv top felt, and the secondary top felt were all
about 7.75 feet wide and were respectively about 104 - -
feet, 62 feet, 66 feet and 42 feet long (i.e. the
treatment areas were respectively about 74.9m2, 44.7m2,
47.5m2 and 30.3m2).
During the test relative porosities as measured by
vacuum (e.g. inches HgJ were monitored across the
widths of the treated felts as well as across the width
of the untreated secondary bottom felt. A substantial
increase in vacuum would represent deterioration of the
felt. The results are shown in Tables I through V.
TA~LE I
PRIMARY BOTTOM FELT POROSITY
Time Feed RatesP~elative Porosity (inches Hg)
~Min.~ (Approximat~)Front Front Center Back Back
After g/min/m End Center Center End
Start Polymer Surfactant
Following Pretreatment 9 8 10 11 8
0 Feed Started - - - - - -
0.02 0.02 9 8 10 11 8
0.02 0.02 11 9 8 8 8 -
0.02 0.02 10 8 8 8 8
100 0.03 0.03 10 10 9 9 10 ~`
25 135 0.03 0.03 11 10 10 10 9
215 0.03 0.03 10 10 9 9 10
245 Feed Stopped - - - - -
~65 0 0 10 10 10 10 10
'. . ":
- 36 - ~
1319778
.. ..
TABI.E II ~-
" '
SUCT~ON DRUM COUCH FELT POROSITY
Time Feed Rates Relative Porosity (inches Hg)
(~in.) (Approximat~) Front Front Center Back Back
After q/min/m End Center Center End -
Start Polymer Surfactant
Following Pretreatment 2 2 2 2 2
Feed Started - - - - - -
0,03 0.03 2 2 2 2 2 -
0.03 0.03 3 3 3 2 3
0.03 0.03 3 3 3 3 3
100 0.05 0.05 2 2 2 2 2
135 0.05 0.05 3 3 2 2 2
215 0.05 0.05 4 4 3 3 5
245 Feed Stopped - - - - - -
265 0 0 3 3 3 3 3
290 4 3 3 3 3
~ '
TABLF. III -
PRIMARY TOP FELT POROSITY
Time Feed Rates Relative Porosity (inches Hg)
(Min.) (Approximat~) Front Front Center Back Back -
After g/min/m End Center Center End
Start Polymer Surfactant ~
Following Pretreatment 3 4 4 4 4 -
Feed Started
0.03 0.03 3 4 4 4 4 :~
0.03 0.03 4 4 4 4 4
0.03 0.03 4 4 4 4 4
100 0.05 0.05 4 4 4 4 4
135 0.05 0.05 5 5 5 4 4
215 0.05 0.05 5 5 4 5 5
245 Feed Stopped
265 0 0 5 4 4 4 4
:
.
- 37 -
1319778
TABLE IV
SECONDARY TOP FELT POROSITY
Time Feed RatesRelative Porosity (inches Hg)
(Min.) (Approximat~)Front Front Center Back Back
S After g/min/m End Center Center End
Start Polymer Surfactant
Following Pretreatment 2 3 3 3 3
Feed Started - - - - -
0.05 0.05 2 3 3 3 3
0.05 0.05 2 1 1 0 1
0.05 0.05 2 2 3 3 3
100 0.07 0.07 2 3 2 2 2 ~:
135 0.07 0.07 3 3 2 2 2 ::
215 0.07 0.07 4 4 5 4 4
l5 245 Feed Stopped
265 0 0 4 4 5 4 4
- ' ~
TABLE V ::~
" ''~
SECONDARY BOTTOM FELT POROSITY (UNTREATED)
Time Feed Rates Relative Porosity (inches Hg) : ::
(Min.? (Approximat~) Front Front Center Back Back
After g/min/m End Center Center End
Start Polymer Surfactant
: . .
Following Pretreatment 3 3 5 4 5
Feed Started - - - - - .:: :;
0 0 3 3 5 4 5 :
0 0 5 4 4 5 4 ~ `
0 0 5 5 4 4 4 .
1 0 0 0 4 4 4 4 3 :::
135 0 0 5 5 5 4 5 .: :.
215 0 0 5 5 5 3 3 : :.
2 6 5 0 ~ 5 5 3 4 5
. _ '. '
-- 38 --
1319778
It will be evident from Tables I through V that
cationic polymer can be applied to papermill felts in
accordance with this invention without plugging the felts
and destro~ing their porosity. Press loadings (i.e. the
pressure applied by the press rolls of the six presses in
the papermaking machine) remained unchanged throughout the
test period; and vacuum pressures (i.e. the suction
applied to remove liquid from the felts) measured at 13
points amongst the primary bottom felt, the suction drum
couch felt, the primary top felt, the secondary top felt
and the secondary ~ottom felt, also remain unchanged
throughout the test period. The couch vacuum remained
unchanged durinq the test. Various sheet characteristics
were also monitored during the test and are summarized in
Table VI.
TABLE VI
SHEET CHARACTERISTICS
, , - - . ::
Time --
~Min.)
After Speed Moisture Basis ~eight Caliper*
Start ~m/min) (percent) ~g/m ) (microns)
.
After
Pretreatment 69.6 5.9 552.4 802.9
Machine Speed Reduced before Start of ~est -
15 66.9 4.6 557.3 820.4 -
50 66.9 3.2 538.9 813.9
Stock flow increased due to low moisture and caliper
100 Treatment Feed Rate Increased
215 69.6 4.5 550.2 823.8
245 Treatment Stopped
265 71.4 4.9 551.7 822.6
- - ' ~
*It was discovered that caliper was reading 25 microns
higher than actual due to computer error.
'
- 39 -
1319778
The pH of the paper stock was kept at about 6 and
the temperature of the vat was about 38C. The stock
consistency was about 0.37% for cylinders 1 and 7, and was
about 0.40% for cylinders 2, 3, 4, 5 and 6. The grade of
paper remained unchanged during the test. Optimum
moisture content had been considered to be about 5%, and ~-
the optimum caliper had been considered to be about 800.
It will be evident from Table VI that favorable sheet
moisture content could be maintained during treatment, and
that the high speed could be maintained during and after
conditioning of the felts in accordance with this ~ -
invention. ~
~ .
EXAMPLE I I I
1 5 - :
The testing of this example was made on a papermaking
machine having a single wire Fourdrinier with a pick-up
felt and a series of presses and felts leading to a Yankee ;
Drier. The machine normally processed furnish having a
suhstantial proportion (i.e. between about 40% to 100%~ of
de-inked recycle pulp. The paper stock was typically kept
at a pH of 6.0-6.5 and at a temperature of about 40C: and
the mill production rate was about 50 tons per day.
Prior to the testing, the felt required up to 15
washings per day with organic solvent and/or blends of
organic solvent with detergent. About 5 gallons of
solvent per wash (i.e. up to about 75 gallons of solvent
per day) were used. Sol~ent washes were
performed on the run as dictated by sheet quality.
Considerable quantities of paper could not be sold due
to poor sheet quality. The de-inked recycle pulp,
while relatively low cost and therefore desirable in
hi~h proportions, was considered to have contributed to
- 40 - `
:, ,- -:
1319778
runnability problems during processing which could in
turn result in sheet imperfections and/or breaks. As a
practical matter, the proportion of de-inked pulp which
could be used was typically limited to a maximum of
about 60~.
Prior to the testing, a new replacement pick-up felt,
about 2.7 meters wide and 16.2 meters long, was installed.
Two lube showers were provided for the pick-up felt.
Felts of this type had exhibited typical shelf lives of
about 50 days. A new low pressure fan shower was ~-~
installed for the testing on the sheet side of the felt
about 3 feet before the suction box. The shower utilized
fresh water and had 13 nozzles, each rated at 2 U.S.
gallons per minute.
In the testing, a test product containing
approximately 7.5% by weight of an alkyldimethyl benzyl
ammonium chloride mixture, about 7.5% of a polymer
having a molecular weight of about 20,000 and derived
from dimethylamine and epichlorohydrin, and about 85% -
by weight solvent (i.e. the same product that was used
in Examples I and II) was diluted in the fresh shower
water of the new low pressure shower to an estimated
concentration of about 34 ppm each of surfactant and
polymer, and applied to the felt at a rate of about
0.09 g/m2-min each of surfactant and polymer.
While felt porosity was not monitored at this
mill, within several hours of the start of the testing
it was evident that the solvent cleaning frequency for
the felt could be reduced. Moreover, the de-inked pulp
content in the furnish was increased to 100%. The
solvent wash frequency was reduced to 5 to 12 washings
per day for five days, and the solvent required per
wash was reduced to about 3 gallons per wash, resulting
- 41 - ~
: .~
"~',,'' '
~: ~3~977~ ~:
in a reduction of dailv solvent usage by about half
ti.e. up to about 36 gallons per day).
The low pressure shower was then relocated to a
new position after the suction box. The solvent wash
frequency dropped further to about 3 times per day.
The new shower position was thus considered to
represent an improvement.
The furnish content was then changed to 60%
de-inked pulp/40% virgin furnish. For this grade, the
solvent wash frequency decreased to approximately one
wash per day.
In sum, even from this preliminary testing which -
lasted about 18 days, it was evident that treatment of
the felt at this machine in accordance with the
invention described herein could provide considerable cost
savings by facilitating the use of furnish having high
de-inked pulp content without causing unacceptable
runnability problems, by reducing the number of solvent
washes required for efficient production and the volume -
of solvent used for washing, and by reducing the amount
of off-quality finished paper.
The examples describe various embodiments of the
invention. Other embodiments will be apparent to those -
skilled in the art from a consideration of the
specification or practice of the invention disclosed
- herein. It is understood that modifications and
variations may be practiced without departing from the
spirit and scope of the novel concepts of this
invention. It is further understood that the invention
is not confined to the particular formulations and
examples herein illustrated, but it embraces such
modified forms thereof as come within the scope of the
following claims. ~- ~
.~ . :', ,.
- 42 - ~
''".":
