U.S. patent application number 10/238865 was filed with the patent office on 2003-05-01 for fibrous sheet enhancement.
This patent application is currently assigned to Armstrong World Industries, Inc.. Invention is credited to Himmelberger, Karl B., Howle, Matthew.
Application Number | 20030079847 10/238865 |
Document ID | / |
Family ID | 22835700 |
Filed Date | 2003-05-01 |
United States Patent
Application |
20030079847 |
Kind Code |
A1 |
Howle, Matthew ; et
al. |
May 1, 2003 |
Fibrous sheet enhancement
Abstract
A method and composition are disclosed for providing a two-part
polymer binder additive for a fibrous sheet by improving both its
strength and durability. The polymer binder comprises both the
addition of a resin system and an anionic polymer which impart both
increased strength and resistance to moisture and sagging. The
resin system includes a polyamidoamine-epihalohydrin resin, a latex
and an anionic polymer.
Inventors: |
Howle, Matthew; (Hockessin,
DE) ; Himmelberger, Karl B.; (Millersville,
PA) |
Correspondence
Address: |
STEVEN L. SCHMID, ESQ.
WOMBLE CARLYLE SANDRIDGE & RICE
POST OFFICE BOX 7037
ATLANTA
GA
30357-0037
US
|
Assignee: |
Armstrong World Industries,
Inc.
|
Family ID: |
22835700 |
Appl. No.: |
10/238865 |
Filed: |
September 10, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10238865 |
Sep 10, 2002 |
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09916355 |
Jul 27, 2001 |
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60223251 |
Aug 4, 2000 |
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Current U.S.
Class: |
162/168.3 ;
162/168.1; 162/168.2 |
Current CPC
Class: |
D21H 17/375 20130101;
D21H 17/72 20130101; C08L 23/08 20130101; D21H 21/20 20130101; D21H
21/18 20130101; D21H 17/54 20130101; D21H 17/42 20130101; C08L
79/02 20130101; C08L 23/08 20130101; C08L 2666/20 20130101; C08L
79/02 20130101; C08L 77/00 20130101; C08L 79/02 20130101; C08L
2666/02 20130101; C08L 79/02 20130101; C08L 2666/04 20130101 |
Class at
Publication: |
162/168.3 ;
162/168.2; 162/168.1 |
International
Class: |
D21H 011/00 |
Claims
What is claimed is:
1. A polymer binder for a fibrous sheet comprising: a resin system
comprising a polyamidoamine-epihalohydrin resin and a polymer
having repeating units derived from an alkyl halide having at least
one double bond and an alkene; and an anionic polymer.
2. The binder of claim 1, wherein the ratio of resin system to
anionic polymer is between about 0.1:1 to 10:1 by weight.
3. The binder of claim 1, wherein the alkyl halide comprises a
vinyl halide.
4. The binder of claim 1, wherein the alkyl halide comprises a
vinyl halide and the alkene comprises an olefin.
5. The binder of claim 3, wherein the vinyl halide comprises vinyl
chloride and the alkene comprises ethylene.
6. The binder of claim 1, wherein the alkyl halide comprises a
vinyl halide and the alkene comprises ethylene.
7. The binder of claim 1, wherein the anionic polymer is a water
soluble copolymer.
8. A method of forming a fibrous sheet comprising: forming a
fibrous slurry; mixing into the fibrous slurry a resin system
comprised of a polyamidoamine-epihalohydrin resin and a polymer
having repeating units derived from an alkyl halide having at least
one double bond and an alkene; next mixing into the fibrous slurry
an anionic polymer; then forming the fibrous slurry into a fibrous
sheet; and drying the fibrous sheet.
9. The method of claim 8, wherein the ratio of added resin system
to anionic polymer is between about 0.1:1 to about 10:1 by
weight.
10. The method of claim 8, wherein the resin system is added to the
fibrous slurry in an amount between about 1 pound to about 200
pounds per ton dry weight of fibrous slurry.
11. The method of claim 8, wherein the resin system is added to the
fibrous slurry between about 5 pounds per ton to about 60 pounds
per ton dry weight of fibrous slurry.
12. The method of claim 8, wherein the anionic polymer is added to
the fibrous slurry in an amount between about 0.2 pound to about
100 pounds per ton dry weight of fibrous slurry.
13. The method of claim 8, wherein the anionic polymer is added to
the fibrous slurry in an amount between about 2.5 pounds per ton to
about 60 pounds per ton dry weight of fibrous slurry.
14. The method of claim 8, wherein the alkyl halide comprises a
vinyl halide.
15. The method of claim 8, wherein the alkyl halide comprises a
vinyl halide and the alkene comprises an olefin.
16. The method of claim 15, wherein the vinyl halide comprises
vinyl chloride and the alkene comprises ethylene.
17. The method of claim 8, wherein the alkyl halide comprises a
vinyl halide and the alkene comprises ethylene.
18. The method of claim 8, wherein the anionic polymer is a
polyacrylamide copolymer.
19. A fibrous sheet comprising: at least one type of fiber; a resin
system comprising a polyamidoamine-epihalohydrin resin and a
polymer having repeating units derived from an alkyl halide having
at least one double bond and an alkene; and an anionic polymer.
20. The fibrous sheet of claim 19, wherein the ratio of added resin
system to anionic polymer is between about 0.1:1 to about 10:1 by
weight.
21. The fibrous sheet of claim 19, wherein the fiber is selected
from the group consisting of cellulose, mineral fiber, fiberglass,
and combinations thereof.
22. The fibrous sheet of claim 19, further including an organic
binder comprising a starch.
23. The fibrous sheet of claim 19, further comprising a filler
selected from the group consisting of perlite, clay calcium
carbonate and combinations thereof.
24. The fibrous sheet of claim 19, wherein the alkyl halide
comprises a vinyl halide and the alkene comprises ethylene.
25. The fibrous sheet of claim 19, wherein the anionic polymer is a
water soluble copolymer.
Description
[0001] This application claims the priority of U.S. provisional
application Serial No. 60/223,251, filed Aug. 4, 2000.
FIELD OF INVENTION
[0002] The present invention generally relates to fibrous sheets
and more specifically to polymer additives for fibrous sheets.
BACKGROUND
[0003] Fibrous sheets are used for a variety of different purposes
and are comprised of an array of different fibers, binders and
fillers. For example, fibrous sheets can be used as acoustical
ceiling tiles, paper products and furniture board. Primarily,
fibrous sheets are comprised of mineral wool, perlite, cellulosic
fibers, fillers and binders.
[0004] Fibrous sheet production utilizes combinations of fibers,
fillers, bulking agents, binders, water, surfactants and other
additives mixed into a slurry and processed into a fibrous sheet.
Examples of fibers used may include mineral fiber, fiberglass, and
cellulosic material. Mineral wool is a lightweight, vitreous,
silica-based material spun into a fibrous structure similar to
fiberglass. Cellulosic material is typically in the form of
newsprint. Added fillers may include expanded perlite, clay,
titanium dioxide and calcium carbonate. Expanded perlite reduces
material density, and clay enhances fire resistance. Examples of
binders used in the production of fibrous sheets include starch,
latex and reconstituted paper products, which link together and
create a binding system, locking all ingredients into a structural
matrix.
[0005] Organic binders, such as starch, are often the primary
component providing structural adhesion for the fibrous sheet.
Starch is often the preferred organic binder because it is
relatively inexpensive. For example, fibrous sheets containing
newsprint, mineral wool and perlite are often bound together by
starch. Starch imparts both strength and durability to the fibrous
sheet structure.
[0006] Unfortunately, there is a limit to how much starch can be
added before the organic binder's properties begin to decline.
Starch is highly water-soluble and, when partially hydrolyzed,
loses a portion of its ability to bind the fibrous sheet
components. Additionally, water-felted and cast panels tend to
exhibit limited stability under high moisture loads given the
hydrophilic nature of the cellulosic fibers. Furthermore, fibrous
sheet strength and durability cannot simply be enhanced by using
increased quantities of starch and cellulose, since starch
increases a fibrous sheet's susceptibility to moisture and sag.
[0007] Thus, a high degree of starch and cellulose can lead to
sagging and weakening of the board. Also, fibrous sheets having
large quantities of starch require elevated drying rates to remove
excess water from the board. Therefore, there is a need for a
method for increasing both the strength and durability of a fibrous
sheet without the addition of increased quantities of starch.
Additionally, there is a need for a fibrous sheet that is not
susceptible to sagging under high moisture loads and does not
require increased drying times during processing.
SUMMARY
[0008] The present invention encompasses both a method and
composition for providing a two-part polymer binder additive for a
fibrous sheet for improving both its strength and durability. The
two-part polymer binder may be added to augment current organic
binders to increase such desirable board properties as strength and
durability, or the polymers may be added to reduce the amount of
organic binder required. Additionally, the polymers may be added in
place of conventional organic binders or added to improve sag
resistance in highly moist environments.
[0009] The two-part polymer binder comprises both the addition of a
resin system and an anionic polymer which impart both increased
strength and resistance to moisture and sagging. The resin system
comprises a polyamidoamine-epihalohydrin resin and a polymer having
repeating units derived from an alkyl halide having at least one
double bond and an alkene.
[0010] In greater detail, the two-part polymer binder may be in a
ratio of resin system to anionic polymer between about 0.1 to 1 and
about 10 to 1 by weight. Additionally, the alkyl halide may
comprise an alkyl halide and the alkene may comprise an olefin or
an ethylene. Furthermore, the anionic polymer may be a water
soluble copolymer.
[0011] The method of forming an enhanced fibrous sheet includes the
steps of forming a fibrous slurry and mixing into the fibrous
slurry a resin system. The resin system comprises a
polyamidoamine-epihalohydrin resin and a polymer having repeating
units derived from an alkyl halide having at least one double bond
and an alkene. Next, added into the mix is an anionic polymer to
form a flocculated mix, which is then formed into a fibrous sheet.
The fibrous sheet is then dried to form the finished product.
[0012] Furthermore, the ratio of added resin system to anionic
polymer may be between about 0.1 to 1 and 10 to 1 by weight. The
resin system may be added to the formed fibrous slurry in an amount
between about 2 pounds to about 200 pounds per ton of fibrous
slurry.
[0013] Additionally, a fibrous sheet is provided having at least
one type of fiber and an organic binder. The fibrous sheet also
contains a resin system having a polyamidoamine-epihalohydrin resin
and a polymer having repeating units derived from an alkyl halide
having at least one double bond and an alkene. Furthermore, an
anionic polymer is also contained within the fibrous sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In the drawings:
[0015] FIG. 1 is a graphical presentation of the plotted
indentation data of the control samples as compared to the samples
containing the additive polymers of the present invention;
[0016] FIG. 2 is a graphical presentation of the plotted
compressive yield strength data of the control samples as compared
to the samples containing the additive polymers of the present
invention;
[0017] FIG. 3 is a graphical presentation of the plotted modulus of
rupture (MOR) data of the control samples as compared to the
samples containing the additive polymers of the present
invention;
[0018] FIG. 4 is a graphical presentation of the plotted modulus of
elasticity (MOE) data of the control samples as compared to the
samples containing the additive polymers of the present
invention;
[0019] FIG. 5 is a graphical presentation of the plotted modulus of
rupture (MOR) data of a fiber board sample prepared using an inline
process run as opposed to a batch process containing the additive
polymers of the present invention; and
[0020] FIG. 6 is a graphical presentation of the plotted modulus of
elasticity (MOE) data of a fiber board sample prepared using an
inline process run as opposed to a batch process containing the
additive polymers of the present invention.
DETAILED DESCRIPTION
[0021] The present invention encompasses both a method and
composition for providing a two-part polymer binder additive for a
fibrous sheet by improving both its strength and durability. The
polymer binder comprises both the addition of a resin system and an
anionic polymer which impart both increased strength and resistance
to moisture and sagging. The resin system comprises a
polyamidoamine-epihalohydrin resin and a polymer having repeating
units derived from an alkyl halide having at least one double bond
and an alkene.
[0022] The resin system is essentially a
polyamidoamine-epihalohydrin resin combined with a latex whereby
the resin imparts a cationic charge to the resin system. The
fibrous slurry is commonly anionic and readily associates with the
cationic resin system. The resin system preferably precedes the
addition of the anionic polymer.
[0023] The anionic polymer is preferably added to the fibrous
slurry after the addition of the resin system. The polymer is
preferably a polyacrylamide copolymer, such as HERCOBOND 2000.RTM.
available from Hercules Incorporated of Wilmington, Del. The
addition of the polymer adds a negative charge to the fibrous
slurry and aids in the creation of a complex, which imparts both
durability and strength to the finished fibrous sheet.
[0024] The ratio of resin system to anionic polymer added to the
fibrous slurry by weight may be about 2:1. The ratio may be smaller
or larger than about 2:1, such as for example 0.1:1 or 10:1 by
weight. Additionally, in one embodiment, the resin system is added
to the fibrous slurry in an amount between about 2 pounds to about
200 pounds per ton of fibrous slurry. In an additional embodiment,
the resin system is added to the fibrous slurry in an amount
between about 10 pounds to about 60 pounds per ton of fibrous
slurry.
[0025] Furthermore, the anionic polymer may be added to the fibrous
slurry in an amount between about 0.2 pound to 100 pounds per ton
of fibrous slurry. In an additional embodiment, the anionic polymer
may be added to the fibrous slurry in an amount between about 1
pound to 8 pounds per ton of fibrous slurry. Of course, even
greater amounts may be added to the slurry if the organic binder is
to be replaced by or reduced by the added binders. Essentially, the
upper limit on the quantity of binder added to the fibrous slurry
is limited by economic factors since most organic binders such as
starch are relatively inexpensive as compared to the polymer
binders of the present invention.
[0026] The resin system comprises a mixture of a
polyamidoamine-epihalohyd- rin and a component which cooperates
with or moderates its properties and may be selected from
flexibilizing components. Without wishing to be bound by any one
theory, it is believed that the flexibilizing component functions
to hinder crosslinking of the polyamidoamine-epihalohydrin. Such a
resin system is described in more detail in U.S. patent application
Ser. No. ______ [Attorney Docket No. P19657.S07] and is
incorporated by reference as though set forth in full within this
application.
[0027] In greater detail, the polyamidoamine-epihalohydrin resin
may include polyamidoamine-epihalohydrin resins such as those
disclosed in U.S. Pat. Nos. 2,926,116 and 2,926,154 to KEIM,
incorporated by reference in their entirety herein.
Polyamidoamine-epihalohydrin resins can also be prepared in
accordance with the teachings of U.S. Pat. No. 5,614,597 to BOWER,
commonly assigned to Hercules Incorporated, which is incorporated
by reference in entirety herein. As discussed in U.S. Pat. No.
5,614,597 to BOWER, these processes typically involve reacting
aqueous polyamidoamine with an excess of epihalohydrin to
completely convert amine groups in the polyamidoamine to
epihalohydrin adducts. During the reaction, halohydrin groups are
added at the secondary amine groups of the polyamidoamine.
[0028] After the epihalohydrin has been added and when heat
evolution has subsided, the reaction mixture is heated to effect
crosslinking and viscosity increase. During this reaction,
azetidinium groups are formed. These functional groups are
typically employed to impart wet strength to paper by forming a
strong crosslinked network with the paper fibers.
[0029] Polyamidoamine-epihalohydrin resins for use include
polyamidoamine-epichlorohydrins such as those sold by Hercules
Incorporated of Wilmington, Del., under various trade names.
Preferred polyamidoamine-epihalohydrin resins available from
Hercules include the KYMENE.RTM. resins and the HERCOBOND.RTM.
resins; KYMENE 557H.RTM. resin; KYMENE 557LX.RTM. resin; KYMENE
557SLX.RTM. resin; KYMENE 557ULX.RTM. resin; KYMENE 557ULX2.RTM.
resin; KYMENE 709.RTM. resin; KYMENE 736.RTM. resin; and HERCOBOND
5100.RTM. resin. Of these, KYMENE 557H.RTM. resin and HERCOBOND
5100.RTM. may be used as polyamidoamines, available in the form of
aqueous solutions. It is expressly contemplated that equivalents to
each of the foregoing resins are within the scope of the present
invention.
[0030] Materials for the flexibilizing component may include
copolymers of alkyl halides and alkenes, such as copolymers of
vinyl or alkyl halides and alkenes. Any alkyl halide and any
alkene, which copolymerize to form copolymers with each other, may
be employed. Alkyl halides may include alkyl and/or vinyl halides
of from 2-12 C atoms, from 2-6 C atoms, from 2-4 C atoms and about
2 C atoms. Copolymers of vinyl halides (especially vinyl chloride)
and alkenes, of from 2-12 C atoms, from 2-6 C atoms, from 2-4 C
atoms and of about 2-3 C atoms. Propylene and/or ethylene may be
used.
[0031] Copolymers of vinyl chloride and ethylene may be employed as
the flexibilizing component. Exemplary copolymers of vinyl chloride
and ethylene are disclosed in U.S. Pat. No. 4,673,702 to
IACOVIELLO, and U.S. Pat. No. 4,962,141 to IACOVIELLO, et al.,
incorporated by reference in their entireties herein. These
copolymers (also referred to herein as "EVCl" copolymers) may be
prepared in using any known method. By way of example, they may be
prepared, for example in the form of an emulsion as described in
U.S. Pat. No. 4,962,141 to IACOVIELLO, et al.
[0032] Suitable EVCl copolymer emulsions may be prepared by
copolymerizing the monomers in the presence of suitable emulsifying
agents, such as protective colloids and surfactants, in an aqueous
medium under pressures generally not exceeding about 100 atm and in
the presence of a redox system which is added incrementally. The
copolymerization reaction is performed under an ethylene pressure
which is sufficient to provide the copolymer with about 5 to 35 wt
% ethylene content, preferably about 15 to 25 wt %. Pressures of
about 50 to 100 atm are generally used to afford such an ethylene
content.
[0033] The EVCl copolymer emulsions may additionally contain from
0.1 to 30 weight percent of an external crosslinking agent based
upon the total weight of the copolymer. Suitable external
crosslinking agents include melamine/formaldehyde resins,
polyisocyanates such as water dispersible polymeric methyl diphenyl
diisocyanates and water based phenolic resins.
[0034] In carrying out the polymerization, substantially all of the
polyvinyl alcohol and a portion of the vinyl chloride are initially
charged into the polymerization vessel which is then pressured with
ethylene. At least about 5 wt % and preferably at least about 15 wt
% of the total vinyl chloride to be polymerized is initially
charged into the reactor. The remainder of the vinyl chloride is
added after the initially charged vinyl chloride monomer content
has been substantially reduced. A controlled addition avoids over
pressurization of the reactor. No more than 60% of the vinyl
chloride should be charged initially since a prepolymer must be
generated in-situ in order to obtain the desired stable
emulsions.
[0035] The quantity of ethylene entering the copolymer is
influenced by pressure, mixing, addition rate and the amount of
free radical generating source. The ethylene content of the polymer
can be enhanced by increasing the ethylene pressure, increasing
agitation and increasing the free radical source rate.
[0036] The process of forming EVCl copolymer emulsions may comprise
preparing an aqueous solution containing a polyvinyl alcohol
dispersing agent. The aqueous solution and initial charge of vinyl
chloride may be added to the polymerization vessel, and ethylene
pressure may then be applied to the desired value. The mixture is
mixed thoroughly to dissolve ethylene in the vinyl chloride and
into the water phase. The charge can be conveniently elevated to
polymerization temperature during this mixing period. A
polymerization temperature of about 55.degree. C. and an ethylene
pressure in the range of 750 psig to 1000 psig may be employed to
provide a copolymer with about 20-30 wt % ethylene. Mixing can be
effected by means of an agitator or other known mechanism.
[0037] The polymerization is initiated by introducing initial
amounts of a free radical generating source into the reactor vessel
containing the monomer premix. When employing a redox system,
either the oxidant or reductant component can be added initially to
the aqueous medium containing the polyvinyl alcohol and vinyl
chloride with the other redox component added to initiate the
reaction. Upon initiating the polymerization, any desired monomer
such as the hydroxyalkyl- or carboxylic acid-containing functional
co-monomers disclosed herein may be added incrementally to the
reaction vessel.
[0038] The reaction may generally be continued until polymerization
is no longer self-sustaining and desirably until the residual vinyl
chloride content is below 0.5%. The completed reaction product is
removed from the presence of ethylene and maintained at a
temperature above the Tg of the copolymer while sealed from the
atmosphere. The reaction mixture can also be transferred to a
degasser for removal of unreacted ethylene.
[0039] One skilled in the art would appreciate that generically or
specifically defined reactants and conditions can be substituted by
equivalent reactants and conditions. Especially preferred
copolymers for the flexibilizing component include those marketed
by Air Products and Chemicals, Inc., of Allentown, Pa., under the
trade name AIRFLEX.RTM.; especially AIRFLEX 4530.RTM.. It is
expressly contemplated that equivalents to such vinyl
chloride/ethylene copolymers are within the scope of the present
invention.
[0040] Other materials for the flexibilizing component include
FLEXBOND 325.RTM. (vinyl acetate-acrylic copolymer latex), LUCIDENE
243.RTM. (styrene-acrylic polymer emulsion), HYCAR 26256.RTM.
(acrylic ester copolymer latex) and MORKOTE 1725.RTM. (acrylic
copolymer emulsion). Additionally, water compatible systems such as
copolymers can contain the following monomers: methyl methacrylate,
butyl acrylate, styrene, vinylidene chloride, acrylic acid, and
methacrylic acid. Suitable copolymers include acrylated urethanes
prepared by reacting a hydroxy acrylate or methacrylate; a diol,
polyester or diamine; and a diisocyanate can be used. Preferred
monomers are disclosed in U.S. Pat. No. 5,716,603, which is hereby
incorporated by reference as though set forth in full herein for
its teachings in this regard. Other copolymers that appear to be
useful include acrylic and vinyl acrylic-based materials.
[0041] The anionic component of the two-part polymer binder
additive is an anionic polymer preferably added by weight in the
ratio of one-part per two-parts resin system. The polymer can be
any linear, branched or crosslinked anionic polymer. The polymer
may be a natural or synthetic polymer. For example, the natural
polymer may be carboxymethylcellulose (CMC), and the synthetic
polymer may be a polymer or copolymer of acrylic acid.
[0042] The anionic polymer is preferably water soluble and, by way
of example, may be comprised of an acrylamide or acrylic polymer or
combinations thereof. The molecular weight of the anionic polymer
is not critical, but is preferred to be within a range of up to
about 1 million. Of course, the molecular weight can be greater
than the preferred range which is contemplated for use within the
present two-part polymer system. Polymers having a very low
molecular weight are essentially limited only by economics, since
more polymer must be added to give a desired result.
[0043] In an embodiment, the anionic polymer may be a water soluble
acrylamide terpolymer described in U.S. Pat. No. 5,543,446 and
incorporated by reference as though set forth in full within this
application. The terpolymer comprises a (meth)acrylamide, an
ethylenically saturated, aliphatic carboxylic acid or salt and a
water-soluble polyvinyl monomer. An example of such a terpolymer
can be acrylamide/acrylic acid/methylene-bis-acrylamide having a
molar ratio of about 92/8/0.018. As can be seen from this example,
the water-soluble polyvinyl monomer component of the terpolymer
comprises only a fraction of the terpolymer's total composition,
thus copolymers of acrylamide and acrylic acid may also be
used.
[0044] While not being bound to any one theory, it is believed that
the two-part polymer binder forms a complex, which is crosslinked
and forms a lattice work around the negatively charged fibers of
the slurry sheet forming the board. The resin system is cationic,
and the anionic polymer is anionic. The resin system may be added
first to the fibrous slurry since the slurry or fibrous component
is negatively charged and is attracted to the positively charged
resin system. The anionic polymer is preferably added after the
resin system as the negative charged dry binder can then bind and
crosslink with the positively charged resin system to form a
complex.
EXAMPLES
[0045] The invention will be more easily understood by referring to
the examples of the invention and the control examples that follow.
The following examples are given for illustrative purposes and are
not to be understood as limiting the present invention.
[0046] The modulus of rupture (MOR) of the board is measured by the
procedure given in ASTM D-1037. MOR is calculated as being equal to
3PL/2bd.sup.2 psi where:
[0047] P=peak force required to break the samples (lbs.)
[0048] L=span between the sample supports (inches)
[0049] b=width of the sample (inches)
[0050] d=thickness of the sample (inches)
[0051] MOR is corrected for density variations by multiplying by
D.sup.2 where D=desired density/actual density, wherein the desired
density is 1.40.
[0052] The modulus of elasticity (MOE) is essentially the measure
of flexibility and can be determined using the equation below: 1 M
O E = ( 1 4 ) ( L t ) 3 ( 1 w ) ( F d )
[0053] where:
[0054] MOE=Modulus of elasticity in flexure, [psi]
[0055] L=Length of test span, [in]
[0056] t=Thickness of the sample, [in]
[0057] w=Width of the sample, [in] 2 ( F d ) = Slope of the force -
deflection curve recorded by the Instron , [ l b f / in ]
[0058] The density of the board products set forth in the following
examples is expressed in pounds per board foot (pfd) and is
determined by weighing a sample board having dimensions of one-foot
square and a thickness of one inch. The density calculation for
thinner or thicker boards is computed by dividing the weight of a
one-foot square board sample by the thickness of the board sample
expressed in inches.
[0059] The resin system component, known herein as Example A, can
be prepared by adding 42.2 dry grams of KYMENE 557H wet strength
resin available from Hercules Incorporated of Wilmington, Del., to
25 dry grams of Airflex 4530 available from Air Products and
Chemicals, Inc. of Allentown, Pa., with mechanical stirring. Next
is added 62.5 grams of demineralized water to the mixture to yield
a slightly blue opaque white dispersion that is then stirred for
about 15 minutes at room temperature.
[0060] The resin system component, known herein as Example B, can
be prepared by adding 100 grams of Hercon.RTM. 70 sizing emulsion
available from Hercules Incorporated of Wilmington, Del., to 100
grams of Example A to yield an opaque white dispersion. The
dispersion is then stirred for about 15 minutes at room
temperature.
1TABLE 1 Sample 1 2 3 4 5 6 7 8 9 10 Example A 2 4 6 8 10 (lbs/ton)
Example B 2 4 6 8 10 (lbs/ton) Hercobond 2000 1 2 3 4 5 1 2 3 4 5
(lbs/ton)
[0061] Illustrated in Table 1 are ten sample handsheets prepared
using various formulations for representing fibrous sheet
formulations. Five samples were prepared using Example A as the
resin system component, and the other five were prepared using
Example B as the resin system component. Hercobond 2000.RTM., a
polyacrylamide copolymer, was added to each handsheet formulation
as the anionic polymer component. The resin system component and
the anionic polymer component were added in the weight ratio of
2:1.
[0062] The raw materials comprising each of the handsheets include
mineral wool, cellulose, broke (Scrap Board), clay (filler) and
perlite.
[0063] The raw materials were added into a reactor vessel in the
order listed above and mixed with water having a temperature
between about 95.degree. F. and about 110.degree. F. After the
addition of each material, the ingredients were mixed for
approximately one minute at a standard mixer speed setting of 6
spd. Once the raw materials were mixed, the resin system component
was added and mixed with the raw materials for about 1-3minutes.
After the addition of the resin system component, Hercobond
2000.RTM. was added and mixed for about 1-3 minutes. A retention
aid, Hercules 8102E, was also added and mixed for about 1-3 minutes
after the addition of the Hercobond 2000.RTM..
[0064] The formed fibrous mix of raw materials and component
polymers was formed and pressed into a fibrous sheet of about 14
inches wide by 26 inches in length. The fibrous sheet was first
drained for about 25 seconds and vacuum treated after about 15
seconds to a thickness of about 3/4 inch. The sheet was then
further pressed to a thickness of about 1/2 inch on a porous plate
with pressing conditions pressed to stops of greater than 7 tons
and gauge pressure of 30 seconds. The sheet was the wrapped in foil
and dried for about 1.25 hours at 375.degree. F. and then unwrapped
and dried for about 2.25 hours at 375.degree. F. The sheets were
wrapped in foil to aid in the gelling of the starch under test
conditions. Foil sheets are not required under typical production
runs in an operational plant. The density of the finished
handsheets ranged from between about 1.15 to about 1.25 pounds per
board foot.
2TABLE 2 Sample MOR (psi) MOE (ksi) Control 1 168.9 27.47 Control 2
173.4 28.33 1 189.0 31.36 2 189.0 32.88 3 204.3 33.71 4 208.0 34.13
5 195.8 35.35 6 185.6 30.85 7 180.8 30.94 8 187.9 31.38 9 188.3
31.90 10 190.3 33.94
[0065] Table 2 illustrates the modulus of elasticity (MOE) and the
modulus of rupture (MOR) of the test sample handsheets, plus two
control sheets formed from the same components, except for the
additive polymers of the present application. Table 2 highlights
that the handsheets formed with the additive polymers of the
present application have improved MOE and MOR qualities as opposed
to the control sheets formed without the additives.
3 TABLE 3 Wet Tensile/ Amount of Additive (%) Dry Wet Dry Experi-
Kymene Example Hercobond Tensile Tensile Tensile ment 557H A 2000
(lb/in) (lb/in) (%) 1 0 0 0 25.6 0.7 3 (Con- trol) 2 0.5 0 0 27.8
6.9 25 3 1.0 0 0 29.5 8.5 29 4 0 1.0 0 30.4 7.5 25 5 1.0 0 0.5 31.3
10.0 32 6 0 1.0 0.5 29.4 7.8 27 7 0 0 0 19.4 0.4 2 (Con- trol) 8
0.5 0 0 22.2 4.2 19 9 1.0 0 0 23.5 4.3 18 10 0 1.0 0 24.1 4.8 20 11
1.0 0 0.5 25.4 5.4 21 12 0 1.0 0.5 24.5 4.8 20 13 0 3 1.5 48 12.0
25.0 14 0 6 3.0 60.0 16.5 27.5 15 0 6 1.0 50.0 10.5 21.0
[0066] Illustrated above in Table 3 are the experimental test
results for various cellulosic sheets of paper. The sample sheets
were prepared by introducing one or more of the following polymer
components: Example A, KYMENE.RTM. 557H and HERCOBOND.RTM. 2000
into the pulp mix. Additionally, two control samples were produced
which did not include the addition of the above polymer
components.
[0067] Samples 1 through 6 were prepared using a mixture of
Townsend Paper unbleached kraft pulp and Stone Container
double-lined kraft pulp (which was washed after repulping) in a
ratio of about 3 to 1, respectively. Samples 7-12 were prepared
using a mixture in a ratio of about 1 to 1 of Georgia Pacific St.
Croix Northern Hardwood and Georgianier J Softwood pulp.
[0068] The paper samples were prepared on the JACKSONVILLE PAPER
MACHINE (a pilot paper machine) and refined to 408 cc CSF
("Canadian Standard Freeness") for sample sheets 1-6 and 485 cc CSF
for sample sheets 7-12. The dilution water had 25 pm alkalinity
(NaHCO.sub.3) and 50 pm hardness (CaCl.sub.2).
[0069] The test samples were either prepared with Example A or
KYMENE.RTM. 557H. Additionally, HERCOBOND.RTM. 2000 was added to
both the Example A and KYMENE.RTM. 557H containing samples. The
test data illustrates that the two-part polymer formulation can be
used to impart wet and dry strength to paper. For example, the test
data indicates that Example A, which is about 63% KYMENE.RTM. 557H
and 37% Airflex 4530, provides good wet strength, as measured by
the ratio of wet tensile to dry tensile in experiments 4 and 10
when compared with experiments 2, 3, 8 and 9. Additionally, when
HERCOBOND.RTM. 2000 is added, both wet and dry strength are
improved as illustrated in experiments 5, 6, 11 and 12.
[0070] While Applicants have set forth embodiments as illustrated
and described above, it is recognized that variations may be made
with respect to disclosed embodiments. Therefore, while the
invention has been disclosed in various forms only, it will be
obvious to those skilled in the art that many additions, deletions
and modifications can be made without departing from the spirit and
scope of this invention, and no undue limits should be imposed
except as set forth in the following claims.
* * * * *