U.S. patent application number 11/433365 was filed with the patent office on 2007-11-15 for use of polyvinylamine to improve oil and water sizing in cellulosic products.
Invention is credited to Dennis W. Barton, Thomas E. Taggart.
Application Number | 20070261807 11/433365 |
Document ID | / |
Family ID | 38659253 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070261807 |
Kind Code |
A1 |
Taggart; Thomas E. ; et
al. |
November 15, 2007 |
Use of polyvinylamine to improve oil and water sizing in cellulosic
products
Abstract
The presence of both a water sizing agent and an oil sizing
agent in a paper making furnish is detrimental in that each has an
adverse effect on the sizing property of the other. It has now been
found that this adverse effect can be counteracted or lessened by
the presence in the furnish of a polyvinylamine.
Inventors: |
Taggart; Thomas E.;
(Jacksonville, FL) ; Barton; Dennis W.;
(Jacksonville, FL) |
Correspondence
Address: |
Gary A. Samuels;Hercules Incorporated
Hercules Plaza
1313 North Market Street
Wilmington
DE
19894-0001
US
|
Family ID: |
38659253 |
Appl. No.: |
11/433365 |
Filed: |
May 12, 2006 |
Current U.S.
Class: |
162/158 ;
162/164.1; 162/168.2; 162/183 |
Current CPC
Class: |
D21H 17/56 20130101;
D21H 17/35 20130101; D21H 17/45 20130101; D21H 17/17 20130101; D21H
21/16 20130101; D21H 23/04 20130101 |
Class at
Publication: |
162/158 ;
162/168.2; 162/164.1; 162/183 |
International
Class: |
D21H 21/16 20060101
D21H021/16; D21H 17/00 20060101 D21H017/00 |
Claims
1. In a paper making process in which a furnish is used, which
furnish contains both an oil sizing agent and a water sizing agent
as a part of the materials in the furnish, the improvement in which
the furnish also contains a polyvinylamine.
2. The process of claim 1 in which the oil sizing agent is present
in the furnish in an amount of between 0.005% and 1% active
treatment solids based upon total furnish solids; the water sizing
agent is present in an amount of between 0.005% and 1% active
treatment solids based upon total furnish solids; and the
polyvinlamine is present in an amount of between 0.001% and 1%
active treatment solids based upon total furnish solids.
3. The process of claim 1 in which the oil sizing agent is a
fluorocarbon containing polymer, and the water sizing agent is an
alkyl ketene dimer.
4. The process of claim 2 in which the oil sizing agent is a
fluorocarbon containing polymer, and the water sizing agent is an
alkyl ketene dimer.
5. The process of claim 2 wherein the polyvinylamine has a
hydrolysis level of at least 35%.
6. The process of claim 1 in which the order of addition to the
furnish of oil sizing agent, water sizing agent and polyvinylamine,
is adding the water sizing agent, then adding the polyvinylamine
either before or after the water sizing agent followed by adding
the oil sizing agent.
7. The process of claim 3 in which the order of addition of
fluorocarbon containing polymer, the alkyl ketene dimer and the
polyvinylamine, is adding the alkyl ketene dimer, adding the
polyvinylamine either before or after adding the alkyl ketene
dimer, followed by adding the fluorocarbon containing polymer.
8. A paper furnish that contains an oil sizing agent, a water
sizing agent, and a polyvinylamine.
Description
FIELD OF THE INVENTION
[0001] This invention relates to an improvement in both oil/grease
and water sizing of cellulosic materials, especially paper
products, through the use of a polyvinylamine in combination with
both oil and water sizing agents.
BACKGROUND OF THE INVENTION
[0002] Sizing agents are used in papermaking processes to repel
water or grease; i.e., oils, from adhering or penetrating into the
paper, thus weakening and/or staining the paper. Sizing agents can
be classified into reactive agents or non-reactive agents. They can
also be classified into internal sizing agents or as surface sizing
agents. Reactive sizing agents bond with the paper fibers and are
usually used for internal sizing.
[0003] Sizing agents can be added to the paper furnish before the
furnish enters the wet end of the papermaking machine.
Alternatively, same sizing agents can be sprayed or nipped onto the
newly formed paper as the paper passes through. If the sizing agent
is added to the pulp slurry (i.e., the furnish) it must adhere to
the pulp or it will not be retained in the paper. This can be
achieved by using an agent that is oppositely charged from the
pulp. Sizing agents in paper prevent excess penetration of water or
grease into the paper. They are used where water or grease
resistance is needed in the paper end use. There are no sizing
agents that have adequate resistance properties of both. The most
efficient oil-sizing agents for cellulosics, such as paper, contain
long, linear fluorocarbons chains. Fluorocarbons in general have
low surface energies and are not wetted easily by oil-based
materials. Conversely, agents that contain non-fluorinated
hydrocarbon chains are good water sizing agents.
[0004] However, when a combination of a fluorocarbon-based agent
for oil resistance and a hydrocarbon based product for water
resistance are both employed in paper making processes, each has an
adverse affect on the other's performance. Accordingly, more
material or product must be used to compensate for the adverse loss
of resistant properties.
[0005] As described by Bottorff in U.S. Pat. No. 5,252,754, long
chained fluorocarbons are efficient oil sizing agents for
cellulosic materials such as paper due to their low surface energy.
However, these fluorocarbon-based sizing agents are generally
inefficient for water resistance, especially if they contain
hydrophilic salt groups. On the other hand, hydrocarbon-based size
products such as alkyl ketene dimer (AKD), are effective water
sizing agents but are inefficient for oil sizing purposes. When
combinations of both hydrocarbon and fluorocarbon-based materials
are used, they have a negative impact on each other's performance
in paper. This adverse relationship generally results in
inefficient treatment schemes because elevated product levels are
required to achieve both adequate oil and water resistance
properties in the same paper.
[0006] It has now been discovered that the presence of a
polyvinylamine in a paper or board furnish which furnish contains
both oil (or grease), and water-sizing agents, the adverse effect
is surprisingly counteracted.
SUMMARY OF THE INVENTION
[0007] In one aspect, the invention is a papermaking or board
making process in which a furnish contains both an oil sizing agent
and a water sizing agent. The improvement being that the furnish
also contains a polyvinylamine.
[0008] Another aspect of the invention is the order of addition of
the agents to the furnish. A water sizing agent is added to a paper
furnish. The polyvinylamine is then added to the paper furnish
either before or after the water sizing agent is added, followed by
adding the oil sizing agent.
[0009] In addition the invention provides a paper furnish which
contains at least one polyvinylamine, a water sizing agent and an
oil sizing agent.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Adding a water-soluble cationic polyvinylamine when both an
oil size and a water size are used in the papermaking process is an
important aspect of the invention.
[0011] The furnish (i.e., pulp) is passed through a paper machine
consisting of a head box, a sheet forming section and a drying
section, all in sequence.
[0012] Polyvinylamines useful in this invention include but are not
limited to ones produced through free radical solution
polymerization of n-vinylformamide. The resulting nonionic
polyvinylformamide can then be base-hydrolyzed, creating a primary
amine cationic functionality on the polymer and sodium formate as a
byproduct. Products effective for the purpose include, but are not
limited to, vinylamine polymers that have been reacted to a
hydrolysis level of 35-100% velocity 50-100% with molecular weight
ranging from 300,000-400,000 via size exclusion chromatography
(SEC) Copolymers of polyvinylamine can be used. Comonomers include
vinyl acetate or vinyl propionate monomers.
[0013] The polyvinylamine polymers can be incorporated into the
aqueous suspension of fibers used to form the web, i.e., the
furnish.
[0014] By furnish is meant the mixture of various materials that
are blended in the stock suspension from which paper or board is
made; the chief constituents are fibrous material (pulp), sizing or
strength materials, or other additives such as fillers and
dyes.
[0015] By pulp is meant fibrous materials prepared from wood,
cotton, grasses, etc, by chemical or mechanical processes for use
in making paper, board, or cellulose products.
[0016] By wire is meant a woven material made of plastic or metal
for use in forming the web of paper or board from the dilute pulp
slurry.
[0017] By headbox is meant a flow control chamber that receives the
dilute paper stock or furnish from the stock preparation system and
acts to spread the flow uniformly across the full width of the
forming wire.
[0018] By sheet forming is meant the process by which the dilute
fiber furnish is formed into a wet web through vacuum and gravity
drainage effects.
[0019] By drying section is meant the part of the papermaking
process that involves the removal of excess water from the wet web
of paper or board through direct contact with heated-drying
cylinders.
[0020] By web is meant the sheet of paper or board coming from a
paper machine in its full width.
[0021] Suitable water sizing agents include alkyl ketene dimers
(AKD) or alkenyl ketene dimer (AKD), alkenyl succinic anhydride
(ASA), rosin-based sizes such as rosin soap, dispersed rosin, and
the like.
[0022] Suitable oil sizing agents include fluorocarbon-containing
polymers such as those which have fluorinated alkyl groups.
[0023] In a preferred process aspect of the invention, the oil size
and water size can be added to the furnish in amounts of 0.005% to
1.0% (weight percent) active treatment solids based upon total
furnish solids, and the polyvinylamine can be present in an amount
of between 0.001% and 1% active treatment solids based on upon
total furnish solids.
[0024] The following Example A highlights the typical adverse
relationship between oil and water sizing agents in cellulose-based
systems requiring high levels of water and oil sizing.
EXAMPLE A
[0025] To make handsheets of paper, a Noble and Wood laboratory
former was used to prepare 20 cm.times.20 cm handsheets at a basis
weight of 160 grams/square meter.
[0026] A furnish containing bleached softwood Kraft pulp and
bleached chemi-thermomechanical pulp were obtained from a
commercial specialties manufacturer requiring significant water and
oil sizing properties. The pulps were blended at a 1:1 ratio and
refined in a laboratory cycle beater to 470 ml Canadian Standard
Freeness (CSF). As outlined in Table A, commercial water and oil
sizing agents were added sequentially to aliquots of the pulp.
Stock agitation was accomplished with an overhead mixer assembly
set at 1,400 rpm. The oil size treatment was added to the pulp
(furnish), 30 seconds after the addition of the water sizing agent.
Handsheet preparation commenced after an additional 30 seconds of
mix time following the oil size treatment. Handsheets were formed
on a 100 mesh screen, passed through a felted roll press set at 35
psi (single pass), and dried to 3-4% moisture using a drum
dryer.
[0027] Performance testing was conducted with both a Hot Water Cobb
test and a Hot Oil Cobb test to demonstrate water and oil
resistance properties in the finished paper. The procedures for
these tests are set forth below. The Hot Water Cobb test involves
paper samples cut to 12.5 cm.times.12.5 cm, weighed to the nearest
0.01 g, and subsequently clamped inside a 100 ml Cobb ring
apparatus. A 50 ml sample of water at 180.degree. F. is then poured
into the Cobb ring and on top of the paper. After exactly two (2)
minutes of contact time with the paper sample, the water is quickly
poured from the ring. The wetted paper sample is removed from the
apparatus and placed between two pieces of blotting paper (wetted
side up). The excess water is removed from the paper specimen by
moving a Cobb hand roller once back and forth over the sample
without exerting any additional force. The wetted paper sample is
immediately reweighed to the nearest 0.01 g. The weight of water
absorbed in grams per square meter is calculated by subtracting the
conditioned weight of the sample from its final weight and
multiplying by 100.
[0028] The Hot Oil Cobb test is identical to the Hot Water Cobb
Test except that oil (Wesson.RTM. Corn Oil) is used at 220.degree.
F. in place of the water. The only other difference in the oil
testing is that the Cobb hand roller is not used to remove the
excess oil but rather the wetted paper sample is pressed by hand
between blotter paper before the sample is gently wiped with a
clean Kimwipes.RTM. towel. The Hot Oil Cobb test quantifies the
weight of the hot oil absorbed in grams/square meter using the same
calculation described under the Hot Water Cobb test.
[0029] In both the Hot Water and the Hot Oil Cobb tests, a higher
test result indicates a greater degree of absorption by the paper
sample. Conversely, a lower Cobb test value is indicative of low
surface welting and penetration and better sizing properties. The
data in Table A shows the typical negative impact of a water sizing
agent on the performance of an oil sizing product. For example, as
the treatment level of the water size is increased, the water
sizing improved while the oil size property is reduced. The water
sizing agent is comprised of alkyl ketene dimer while the oil size
is a perfluoroalkyl-containing product. TABLE-US-00001 TABLE A
Water and Oil Sizing Results Commercial Water Commercial Oil Hot
Water Hot Oil Size Size Cobb Cobb (wt. %) (wt. %) (g/m.sup.2)
(g/m.sup.2) 0.132 0.225 162 89 0.155 0.225 71 118
[0030] The following definitions apply for Table A: [0031]
Commercial AKD Water Size: Hercon.RTM. 79--Hercules Incorporated
[0032] Commercial Oil Size: imPress.RTM. FP-100--Hercules
Incorporated [0033] Weight %: % Addition of Active Treatment Solids
Based Upon Total Furnish Solids
[0034] The following Examples are illustrative of the surprising
beneficial effect of polyvinylamine on both water and oil
resistance in cellulose-based systems requiring high levels of
water and oil sizing.
EXAMPLE 1
[0035] The data from Example 1 is summarized in Table 1. In this
study, handsheets were prepared using the same papermaking
procedure described in Example A with the exception that the
furnish was comprised of 60% southern bleached softwood Kraft and
40% northern bleached hardwood Kraft commercial market pulps
refined to 480 ml Canadian Standard Freeness (CSF). The target
basis weight was 248 grams/square meter. The chemical addition
sequence was as described in Example A except that when
polyvinylamine was included in the testing, it was added to the
mixing furnish 30 seconds prior to the addition of the water sizing
agent. Handsheet performance testing was conducted using the same
procedures as described in Example A except that a 2% Ambient
Saline Cobb test was conducted in place of the Hot Water Cobb test.
The saline used in the test is at ambient temperature and is
derived from deionized water treated with NaCl at 2% by weight.
Aside from these differences, the test procedure is identical to
the Hot Water Cobb test method described in Example A.
[0036] The data summarized in Table 1 shows the simultaneous
positive effect of polyvinylamine on both water and oil sizing test
results. The low Saline and Hot Water Cobb test values demonstrate
that an effective balance in water and oil resistance is achieved
through the addition of the polyvinylamine. The water sizing agent
is comprised of alkyl ketene dimer while the oil size is a
perfluoroalkyl-containing product. The polyvinylamine is a solution
polymer that has been reacted to a hydrolysis level of 50%.
TABLE-US-00002 TABLE 1 Water and Oil Sizing Results Commercial
Commercial Commercial 2% Ambient Hot Oil Polyvinylamine Water Size
Oil Size Saline Cobb Cobb (wt. %) (wt. %) (wt. %) (g/m.sup.2)
(g/m.sup.2) 0 0.075 0.15 51 134 0.013 0.075 0.15 35 116 0 0.075
0.20 111 111 0.013 0.075 0.20 31 33
[0037] The following definitions apply for Table 1: [0038]
Commercial Polyvinylamine: Hercules.RTM. PPD M-1189--Hercules
Incorporated [0039] Commercial AKD Water Size: Hercon.RTM.
80--Hercules Incorporated [0040] Commercial Oil Size: imPresse
FP-100--Hercules Incorporated [0041] Weight %: % Addition of Active
Treatment Solids Based Upon Total Furnish Solids
EXAMPLE 2
[0042] The data from Example 2 is summarized in Table 2. In this
work, handsheets were prepared to 160 grams/square meter using the
same papermaking procedure and furnish blend described in Example
A. The target Canadian Standard Freeness for pulp refining was 470
mls. The chemical addition sequence was consistent with the
description provided in Example A except that when an anionic
polymer was included in the testing, it was added to the mixing
furnish 30 seconds after to the addition of the water sizing agent
and 30 seconds prior to the addition of the oil size material. When
polyvinylamine was included in the testing, it was added to the
mixing furnish 30 seconds prior to the addition of the water sizing
agent. Handsheet performance testing was conducted using the same
procedures as described in Example A.
[0043] The data in Table 2 further demonstrates the beneficial
effect of polyvinylamine on both water and oil sizing properties as
low Cobb values are achieved with the addition of polyvinylamine to
the test furnish. The water sizing agent is comprised of alkyl
ketene dimer. The oil size is a perfluoroalkyl-containing product,
and the polyvinylamine is a solution polymer that has been reacted
to a hydrolysis level of 50%. The anionic polymer is a solution
copolymer of acrylamide and acrylic acid (Hercobond 2000). Anionic
polymer is used as a retention aid to enhance the retention of fine
solids in the web during the sheet forming process. TABLE-US-00003
TABLE 2 Water and Oil Sizing Results Commercial Commercial Commer-
Hot Hot Poly- Commercial Anionic cial Water Oil vinylamine Water
Size Polymer Oil Size Cobb Cobb (wt. %) (wt. %) (wt. %) (wt. %)
(g/m.sup.2) (g/m.sup.2) 0 0.35.sup.(1) 0 0.24 74 40 0 0.35.sup.(1)
0.2 0.24 99 51 0.1 0.35.sup.(1) 0.2 0.24 49 39 0.05 0.125.sup.(2) 0
0.24 255 53 0.1 0.125.sup.(2) 0 0.24 82 39 0.2 0.125.sup.(2) 0.1
0.24 43 35
[0044] The following definitions apply for Table 2: [0045]
Commercial Polyvinylamine: Hercules.RTM. PPD M-1189--Hercules
Incorporated [0046] Commercial Water Size (1): 60:40 Blend
ReTen.RTM. 204LS/Hercon.RTM. 70--Hercules Incorporated [0047]
Commercial Water Size (2): Hercon.RTM. 70--Hercules Incorporated
[0048] Commercial Anionic Polymer: Hercobond.RTM. 2000--Hercules
Incorporated [0049] Commercial Oil Size: imPress.RTM.
FP-100--Hercules Incorporated [0050] Weight %: % Addition of Active
Treatment Solids Based Upon Total Furnish Solids.
EXAMPLE 3
[0051] The data from Example 3 is summarized in Table 3. In this
study, handsheets were prepared using the same papermaking
procedure described in Example A with the exception that the
furnish was comprised of 70% southern bleached softwood Kraft and
30% northern bleached hardwood Kraft commercial market pulps
refined to 405 ml Canadian Standard Freeness. The target basis
weight was 149 grams/square meter. The chemical addition sequence
was consistent with the description provided in Example A except
that when either the polyvinylamine or branched polyamine were
included in the testing, it was added to the mixing furnish 30
seconds prior to the addition of the water sizing agent. In
addition, the anionic polymer and colloidal silica were added in
sequential order 30 seconds after the addition of the water size
and 30 seconds prior to the addition of the oil sizing agent with
30 seconds of mix time between each product addition. Handsheet
performance testing was conducted using the same procedures as
described in Example A
[0052] The data in Table 3 summarizes the positive effect of
polyvinylamine on water and oil sizing results. The trends
associated with the polyvinylamine further demonstrate that it is
possible to reduce the addition level of the water and oil sizing
agents while maintaining an effective low balance of Cobb test
values indicative of high water and oil resistance properties. The
test data associated with the branched polyamine indicate that it
is difficult to achieve the same effective balance in water and oil
sizing properties as compared to the test conditions involving
polyvinylamine.
[0053] In this example, the branched polyamine is a solution
polymer with quaternary amine functionality. The polyvinylamine is
a solution polymer that has been reacted to a hydrolysis level of
50% with a predominantly linear structure and primary amine
functionality. The water sizing agent is comprised of alkyl ketene
dimer, while the oil size is a perfluoroalkyl-containing product.
The anionic polymer is an emulsion copolymer of acrylamide and
acrylic acid. The silica component is an aqueous dispersion of
colloidal silica particles. The anionic polymer and colloidal
silica are added to the furnish with the purpose of increasing the
retention of fine solids in the paper web in the forming process.
TABLE-US-00004 TABLE 3 Water and Oil Sizing Results Commercial
Commercial Commercial Commercial Hot Hot Branched Poly- Commercial
Anionic Colloidal Commercial Water Oil Polyamine vinylamine Water
Size Polymer Silica Oil Size Cobb Cobb (wt. %) (wt. %) (wt. %) (wt.
%) (wt. %) (wt. %) (g/m.sup.2) (g/m.sup.2) 0.35 0 0.14 0.29 0.09
0.15 49 95 0.35 0 0.14 0.29 0.09 0.17 51 55 0.35 0 0.14 0.29 0.09
0.19 47 39 0.35 0 0.14 0.29 0.09 0.21 51 41 0.35 0 0.14 0.29 0.09
0.23 76 39 0.30 0 0.14 0.29 0.09 0.19 49 36 0.40 0 0.14 0.29 0.09
0.19 57 39 0 0.15 0.14 0.29 0.09 0.19 39 47 0 0.20 0.14 0.29 0.09
0.19 39 36 0 0.20 0.12 0.29 0.09 0.17 39 34 0 0.20 0.10 0.29 0.09
0.15 40 33
The following definitions apply for Table 3: [0054] Commercial
Branched Polyamine: Nalco 7607--Nalco [0055] Commercial
Polyvinylamine: Hercules.RTM. PPD M-1189--Hercules Incorporated
[0056] Commercial Water Size: Hercon.RTM. 79--Hercules Incorporated
[0057] Commercial Anionic Polymer: PerForm.RTM. PA8137--Hercules
Incorporated [0058] Commercial Colloidal Silica: Positek
8691--Nalco [0059] Commercial Oil Size: imPress.RTM.
FP-100--Hercules Incorporated [0060] Weight %: % Addition of Active
Treatment Solids Based Upon Total Furnish Solids
* * * * *