U.S. patent application number 10/242571 was filed with the patent office on 2004-03-11 for method for using water insoluble chemical additives with pulp and products made by said method.
Invention is credited to Coe, Louise Cynthia Ellis, Goulet, Mike Thomas, Hu, Sheng-Hsin, Moline, David Andrew, Negri, Alberto Ricardo, Payne, Michael, Runge, Troy Michael, Shannon, Thomas Gerard, Wright, Alan Edward.
Application Number | 20040045687 10/242571 |
Document ID | / |
Family ID | 31991444 |
Filed Date | 2004-03-11 |
United States Patent
Application |
20040045687 |
Kind Code |
A1 |
Shannon, Thomas Gerard ; et
al. |
March 11, 2004 |
Method for using water insoluble chemical additives with pulp and
products made by said method
Abstract
Pulp fibers can be treated with water insoluble chemical
additives resulting in a minimal amount of unretained water
insoluble chemical additives present after exposing the treated
pulp fibers to process water, liquids, or solutions used in
products. One embodiment of the present invention is a method for
preparing chemically treated pulp fiber. A fiber slurry is created
comprising process water and pulp fibers. The fiber slurry is
transported to a web-forming apparatus of a pulp sheet machine
thereby forming a wet fibrous web. The wet fibrous web is dried to
a predetermined consistency thereby forming a dried fibrous web.
The dried fibrous web is treated with a water insoluble chemical
additive thereby forming a chemically treated dried fibrous web
containing chemically treated pulp fibers. The chemically treated
pulp fibers have an improved level of chemical retention of the
water insoluble chemical additive and retain from between about 25
to about 100 percent of the applied amount of the water insoluble
chemical additive when the chemically treated pulp fibers are
exposed to a liquid, such as water. The chemically treated pulp
fibers are used to form a fibrous non-woven material.
Inventors: |
Shannon, Thomas Gerard;
(Neenah, WI) ; Coe, Louise Cynthia Ellis;
(Appleton, WI) ; Goulet, Mike Thomas; (Neenah,
WI) ; Hu, Sheng-Hsin; (Appleton, WI) ; Moline,
David Andrew; (Appleton, WI) ; Negri, Alberto
Ricardo; (Appleton, WI) ; Payne, Michael;
(Roswell, GA) ; Runge, Troy Michael; (Neenah,
WI) ; Wright, Alan Edward; (Woodstock, GA) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
|
Family ID: |
31991444 |
Appl. No.: |
10/242571 |
Filed: |
September 11, 2002 |
Current U.S.
Class: |
162/158 ; 162/9;
424/402 |
Current CPC
Class: |
D21H 21/10 20130101;
D21H 23/28 20130101; D21C 9/002 20130101 |
Class at
Publication: |
162/158 ;
162/009; 424/402 |
International
Class: |
D21F 011/00; D21H
017/00; D21C 009/00 |
Claims
We claim:
1. A method for preparing chemically treated pulp fibers
comprising: a) creating a fiber slurry comprising process water and
virgin pulp fibers; b) transporting the fiber slurry to a
web-forming apparatus of a pulp sheet machine and forming a wet
fibrous web; c) drying the wet fibrous web to a predetermined
consistency thereby forming a dried fibrous web; d) treating the
dried fibrous web with a water insoluble chemical additive thereby
forming a chemically treated dried fibrous web containing
chemically treated pulp fibers, wherein the chemically treated pulp
fibers have an improved level of chemical retention of the water
insoluble chemical additive and retain from between about 25 to
about 100 percent of the applied amount of the water insoluble
chemical additive when the chemically treated pulp fibers are
exposed to a liquid; and, e) using the chemically treated pulp
fibers having the water insoluble chemical additive retained
thereon to form a fibrous non-woven material.
2. The method of claim 1, wherein the fibrous non-woven material is
coform.
3. The method of claim 1, wherein the dried chemically treated
fibrous web includes a gradient of the water insoluble chemical
additive.
4. The method of claim 1, further comprising dewatering the wet
fibrous web thereby forming a dewatered fibrous web.
5. The method of claim 4, further comprising drying the dewatered
fibrous web thereby forming the dried fibrous web.
6. The method of claim 5, wherein the fibrous non-woven material
comprises polypropylene.
7. The method of claim 2, further comprising producing a finished
product having enhanced quality due to the retention of the water
insoluble chemical additive by the chemically treated pulp
fibers.
8. The method of claim 1, wherein the water insoluble chemical
additive is selected from the group comprising softening agents,
dry strength agents, wet strength agents, opacifying agents, dyes,
debonding agents, absorbency agents, sizing agents, optical
brighteners, chemical tracers, and mixtures thereof.
9. The method of claim 1, wherein the water insoluble chemical
additive is selected from the group consisting of: mineral oil;
petrolatum; olefins; alcohols; fatty alcohols; ethoxylated fatty
alcohols; esters; high molecular weight carboxylic and
polycarboxylic acids and their salts; polydimethylsiloxane and
modified polydimethylsiloxane; and, mixtures thereof.
10. The method of claim 1, wherein the fibrous non-woven material
comprises at least 2 plies.
11. The method of claim 1, wherein the water insoluble chemical
additive is applied to the dried fibrous web in an amount of at
least about 0.1 kilograms per metric ton or greater.
12. The method of claim 1, wherein the fibrous non-woven material
comprises at least 2 layers.
13. The method of claim 1, wherein sufficient residence time is
provided after the water insoluble chemical additive is applied to
the dried fibrous web to allow for retention of the water insoluble
chemical additive by the chemically treated pulp fiber of the dried
fibrous web.
14. The method of claim 1, further comprising forming a wet-wipe
product from the chemically treated dried fibrous web.
15. A wet-wipe product made using the method of claim 1.
16. The wet-wipe product of claim 15, wherein the amount of the
water insoluble chemical additive applied to the dried fibrous web
is about 0.1 kilogram per metric ton or greater.
17. A method for applying a water insoluble chemical additive to a
fibrous non-woven material, the method comprising: a) mixing pulp
fibers with process water to form a pulp fiber slurry; b)
transporting the fiber slurry to a web-forming apparatus of a pulp
sheet machine and forming a wet fibrous web; c) dewatering the wet
fibrous web to a predetermined consistency thereby forming a
dewatered fibrous web; d) applying a water insoluble chemical
additive to the dewatered fibrous web thereby forming a chemically
treated dewatered fibrous web containing chemically treated pulp
fibers, wherein the chemically treated pulp fibers have an improved
level of chemical retention of the water insoluble chemical
additive and retain from between about 25 to about 100 percent of
the applied amount of the water insoluble chemical additive when
the chemically treated pulp fibers are exposed to a liquid; and, e)
using the chemically treated pulp fibers having the water insoluble
chemical additive retained thereon to form a fibrous non-woven
material.
18. The method of claim 17, further comprising transporting the
chemically treated dewatered fibrous web to a manufacturing machine
and mixing the chemically treated pulp fiber having the water
insoluble chemical additive retained thereon with a thermoplastic
polymeric material.
19. The method of claim 17, wherein the chemically treated
dewatered fibrous web includes a gradient of the non-watered
soluble chemical additive.
20. The method of claim 17, further comprising drying the
chemically treated dewatered fibrous web to a predetermined
consistency thereby forming a chemically treated dried fibrous
web.
21. The method of claim 20, wherein the chemically treated dried
fibrous web includes a gradient of the water insoluble chemical
additive.
22. The method of claim 20, wherein said fibrous non-woven material
comprises polypropylene.
23. The method of claim 22, further comprising forming a finished
product having enhanced quality due to the retention of the water
insoluble chemical additive by the chemically treated pulp
fibers.
24. The method of claim 22, wherein the amount of the water
insoluble chemical additive retained by the chemically treated pulp
fibers is about 0.1 kilogram per metric ton or greater, and the
amount of unretained the water insoluble chemical additive in the
water is between 0 and about 50 percent of the amount of the
applied water insoluble chemical additive retained by the
chemically treated dried fibrous web.
25. The method of claim 17, wherein the amount of the water
insoluble chemical additive applied to the dewatered fibrous web is
about 1 kilograms per metric ton or greater.
26. The method of claim 17, wherein the amount of the water
insoluble chemical additive applied to the dewatered fibrous web is
about 3 kilograms per metric ton or greater.
27. The method of claim 17, wherein the amount of the water
insoluble chemical additive applied to the dewatered fibrous web is
about 5 kilograms per metric ton or greater.
28. The method of claim 17, wherein the water insoluble chemical
additive is selected from the group comprising softening agents,
dry strength agents, wet strength agents, opacifying agents, dyes,
debonding agents, absorbency agents, sizing agents, optical
brighteners, chemical tracers, and mixtures thereof.
29. The method of claim 17, wherein the water insoluble chemical
additive is selected from the group consisting of: mineral oil;
petrolatum; olefins; alcohols; fatty alcohols; ethoxylated fatty
alcohols; esters; high molecular weight carboxylic and
polycarboxylic acids and their salts; polydimethylsiloxane and
modified polydimethylsiloxane; and, mixtures thereof.
30. A wet-wipe product made from the chemically treated pulp fiber
slurry of claim 17.
31. A method for adding at least a first chemical additive to pulp
fiber contained in a fibrous non-woven material, the method
comprising: a) mixing pulp fibers with process water thereby
forming a fiber slurry; b) transporting the fiber slurry to a
web-forming apparatus of a pulp sheet machine; c) dewatering the
fiber slurry thereby forming a crumb pulp; d) applying a water
insoluble chemical additive to the crumb pulp thereby forming a
chemically treated crumb pulp containing chemically treated pulp
fibers, wherein the chemically treated pulp fibers have an improved
level of chemical retention of the water insoluble chemical
additive and retain from between about 25 to about 100 percent of
the applied amount of the water insoluble chemical additive when
the chemically treated pulp fibers are exposed to a liquid; and, e)
using the chemically treated pulp fibers having the water insoluble
chemical additive retained thereon to form a fibrous non-woven
material.
32. The method of claim 31, further comprising transporting the
chemically treated crumb pulp to a manufacturing machine and mixing
the chemically treated pulp fibers having the water insoluble
chemical additive retained thereon with a thermoplastic polymeric
material.
33. The method of claim 32, further comprising transporting the
chemically treated pulp fiber through the manufacturing machine to
form a finished wet-wipe product having enhanced quality due to the
retention of at least a first chemical additive by the chemically
treated pulp fibers.
34. The method of claim 31, further comprising applying a second
chemical additive to the chemically treated crumb pulp.
35. A method for applying water insoluble chemical additives to
pulp fiber contained in a fibrous non-woven material, the method
comprising: a) creating a fiber slurry comprising process water and
pulp fibers; b) transporting the fiber slurry to a web-forming
apparatus of a pulp sheet machine and forming a wet fibrous web; c)
dewatering the wet fibrous web to a predetermined consistency
thereby forming a dewatered fibrous web; d) applying a first water
insoluble chemical additive to the dewatered fibrous web thereby
forming a chemically treated dewatered fibrous web of chemically
treated pulp fibers; e) applying a second water insoluble chemical
additive to the chemically treated dewatered fibrous web thereby
forming a dual chemically treated dewatered fibrous web containing
dual chemically treated pulp fibers, wherein the dual chemically
treated pulp fibers have an improved level of chemical retention of
the first water insoluble chemical additive and retain from between
about 25 to about 100 percent of the applied amount of the first
water insoluble chemical additive when the dual chemically treated
pulp fibers are exposed to a liquid and wherein the dual chemically
treated pulp fibers have an improved level of chemical retention of
the second water insoluble chemical additive and retain from
between about 25 to about 100 percent of the applied amount of the
second water insoluble chemical additive when the dual chemically
treated pulp fibers are exposed to a liquid; and, f) using the dual
chemically treated pulp fibers having the first and second water
insoluble chemical additives retained thereon to form a fibrous
non-woven material.
36. The method of claim 35, further comprising transporting the
dual chemically treated pulp fibers to a manufacturing machine and
mixing the dual chemically treated pulp fibers having the first and
second water insoluble chemical additives retained thereon with a
thermoplastic material.
37. The method of claim 35, further comprising drying the dual
chemically treated dewatered fibrous web to a predetermined
consistency thereby forming a dual chemically treated dried fibrous
web.
38. The method of claim 37, further comprising transporting the
dual chemically treated dried fibrous web to a manufacturing
machine and mixing the dual chemically treated pulp fibers having
the first and second water insoluble chemical additives retained
thereon with a thermoplastic polymeric material.
39. The method of claim 35, wherein the dual chemically treated
dewatered fibrous web includes a gradient of the first water
insoluble chemical additive.
40. The method of claim 35, wherein the dual chemically treated
dried fibrous web includes a gradient of the first water insoluble
chemical additive.
41. The method of claim 35, wherein the dual chemically treated
dewatered fibrous web includes a gradient of the second water
insoluble chemical additive.
42. The method of claim 35, wherein the dual chemically treated
dried fibrous web includes a gradient of the second water insoluble
chemical additive.
43. The method of claim 38, further comprising producing a wet-wipe
product having enhanced quality due to the retention of the first
and second water insoluble chemical additives by the dual
chemically treated pulp fibers.
44. The method of claim 35, wherein the first water insoluble
chemical additive is selected from the group comprising softening
agents, dry strength agents, wet strength agents, opacifying
agents, dyes, debonding agents, absorbency agents, sizing agents,
optical brighteners, chemical tracers, and mixtures thereof.
45. The method of claim 44, wherein the first water insoluble
chemical additive is selected from the group consisting of: mineral
oil; petrolatum; olefins; alcohols; fatty alcohols; ethoxylated
fatty alcohols; esters; high molecular weight carboxylic and
polycarboxylic acids and their salts; polydimethylsiloxane and
modified polydimethylsiloxane; and, mixtures thereof.
46. The method of claim 35, wherein the second water insoluble
chemical additive is selected from the group comprising softening
agents, dry strength agents, wet strength agents, opacifying
agents, dyes, debonding agents, absorbency agents, sizing agents,
optical brighteners, chemical tracers, and mixtures thereof.
47. The method of claim 46, wherein the second water insoluble
chemical additive is selected from the group consisting of: mineral
oil; petrolatum; olefins; alcohols; fatty alcohols; ethoxylated
fatty alcohols; esters; high molecular weight carboxylic and
polycarboxylic acids and their salts; polydimethylsiloxane and
modified polydimethylsiloxane; and, mixtures thereof.
48. The method of claim 35, wherein the first and second water
insoluble chemical additives are applied to the dewatered fibrous
web simultaneously.
49. The method of claim 35, wherein the first water insoluble
chemical additive is applied to the dewatered fibrous web in an
amount of about 0.1 kilograms per metric ton or greater.
50. The method of claim 35, wherein the second water insoluble
chemical additive is applied to the dewatered fibrous web in an
amount of about 0.1 kilogram per metric ton or greater.
51. The method of claim 35, wherein the dual chemically treated
dried fibrous web has a consistency ranging from about 65 percent
to about 100 percent.
52. The method of claim 35, wherein sufficient residence time is
provided after the first water insoluble chemical additive is
applied to the dewatered fibrous web to allow the first water
insoluble chemical additive to be retained by the dual chemically
treated pulp fiber.
53. The method of claim 35, wherein sufficient residence time is
provided after the second water insoluble chemical additive is
applied to the dewatered fibrous web to allow the second water
insoluble chemical additive to be retained by the dual chemically
treated pulp fiber.
54. A wet-wipe product made using the method of claim 35.
55. A method for applying water insoluble chemical additives to
pulp fiber contained in a fibrous non-woven material, the method
comprising: a) mixing pulp fibers with process water to form a
fiber slurry; b) transporting the fiber slurry to a web-forming
apparatus of a pulp sheet machine and forming a wet fibrous web; c)
dewatering the wet fibrous web to a predetermined consistency
thereby forming a dewatered fibrous web; d) drying the dewatered
fibrous web to a predetermined consistency thereby forming a dried
fibrous web; e) applying a first water insoluble chemical additive
to the dried fibrous web and applying a second water insoluble
chemical additive to the dried fibrous web thereby forming a dual
chemically treated dried fibrous web containing dual chemically
treated pulp fibers, wherein the dual chemically treated pulp
fibers have an improved level of chemical retention of the first
water insoluble chemical additive and retain from between about 25
to about 100 percent of the applied amount of the first water
insoluble chemical additive when the dual chemically treated pulp
fibers are exposed to a liquid and wherein the dual chemically
treated pulp fibers have an improved level of chemical retention of
the second water insoluble chemical additive and retain from
between about 25 to about 100 percent of the applied amount of the
second water insoluble chemical additive when the dual chemically
treated pulp fibers are exposed to a liquid; and, f) using the dual
chemically treated pulp fibers having the first and second water
insoluble chemical additives retained thereon to form a fibrous
non-woven material.
56. The method of claim 55, wherein the dual chemically treated
dried fibrous web includes a gradient of the first water insoluble
chemical additive.
57. The method of claim 55, wherein the dual chemically treated
dried fibrous web includes a gradient of the second water insoluble
chemical additive.
58. The method of claim 55, further comprising transporting the
dual chemically treated dried fibrous web to a manufacturing
machine and mixing the dual chemically treated pulp fibers having
at least the first and second water insoluble chemical additives
retained thereon with a thermoplastic material.
59. The method of claim 55, further comprising transporting the
dual chemically treated pulp fiber through the paper machine to
form a finished wet-wipe product having enhanced quality due to the
retention of at least the first and second water insoluble chemical
additives by the dual chemically treated pulp fibers.
60. The method of claim 58, wherein the amount of the first water
insoluble chemical additive retained by the dual chemically treated
pulp fibers is about 0.1 kilogram per metric ton or greater, and
the amount of unretained first water insoluble chemical additive in
the water is between 0 and about 75 percent of the applied amount
of the first water insoluble chemical additive when the dual
chemically treated pulp fibers are exposed to a liquid.
61. The method of claim 58, wherein the amount of the second water
insoluble chemical additive retained by the dual chemically treated
pulp fibers is about 0.1 kilogram per metric ton or greater, and
the amount of unretained second water insoluble chemical additive
in the water is between 0 and about 75 percent of the applied
amount of the second water insoluble chemical additive when the
dual chemically treated pulp fibers are exposed to a liquid.
62. The method of claim 58, wherein the amount of the first water
insoluble chemical additive retained by the dual chemically treated
pulp fibers is about 0.1 kilograms per metric ton or greater, and
the amount of unretained first water insoluble chemical additive in
the water is between 0 and about 75 percent of the applied amount
of the first water insoluble chemical additive when the dual
chemically treated pulp fibers are exposed in a liquid and wherein
the amount of the second water insoluble chemical additive retained
by the dual chemically treated pulp fibers is about 0.1 kilogram
per metric ton or greater, and the amount of unretained second
water insoluble chemical additive in the water is between 0 and
about 75 percent of the applied amount of the second water
insoluble chemical additive when the dual chemically treated pulp
fibers are exposed in a liquid.
63. A paper or tissue product made using the method of claim
55.
64. A method for applying water insoluble chemical additives to
pulp fiber contained in a fibrous non-woven material, the method
comprising: a) mixing pulp fibers with process water to form a
fiber slurry; b) transporting the fiber slurry to a web-forming
apparatus of a pulp sheet machine and forming a wet fibrous web; c)
dewatering the wet fibrous web to a predetermined consistency
thereby forming a dewatered fibrous web; d) applying a first water
insoluble chemical additive to the dewatered fibrous web to the
dewatered fibrous web thereby forming a chemically treated
dewatered fibrous web; e) drying the chemically treated dewatered
fibrous web to a predetermined consistency thereby forming a
chemically treated dried fibrous web; f) applying a second water
insoluble chemical additive to the chemically treated dried fibrous
web, thereby forming a dual chemically treated dried fibrous web
containing dual chemically treated pulp fibers, wherein the dual
chemically treated pulp fibers have an improved level of chemical
retention of the first water insoluble chemical additive wherein
the level of chemical retention of the first water insoluble
chemical additive is between about 25 to about 100 percent
retention of the applied amount of the first water insoluble
chemical additive when the dual chemically treated pulp fibers are
exposed to a liquid and the dual chemically treated pulp fibers
have an improved level of chemical retention of the second water
insoluble chemical additive wherein the level of chemical retention
of the second water insoluble chemical additive is between about 25
to about 100 percent retention of the applied amount of the second
water insoluble chemical additive when the dual chemically treated
pulp fibers are exposed to a liquid; and, g) using the dual
chemically treated pulp fibers having the first and second water
insoluble chemical additives retained thereon to form a fibrous
non-woven material.
65. The method of claim 64, wherein the chemically treated
dewatered fibrous web includes a gradient of the first water
insoluble chemical additive.
66. The method of claim 64, wherein the dual chemically treated
dried fibrous web includes a gradient of the first water insoluble
chemical additive.
67. The method of claim 64, wherein the dual chemically treated
dried fibrous web includes a gradient of the second water insoluble
chemical additive.
68. The method of claim 64, further comprising transporting the
dual chemically treated dried fibrous web to a manufacturing
machine and mixing the dual chemically treated pulp fibers having
at least the first and second water insoluble chemical additives
retained thereon with a thermoplastic polymeric material.
69. The method of claim 64, further comprising transporting the
chemically treated pulp fibers through the manufacturing machine to
form a finished wit-wipe product having enhanced quality due to the
retention of at least the first and second water insoluble chemical
additives by the dual chemically treated pulp fibers.
70. The method of claim 68, wherein the amount of the first water
insoluble chemical additive retained by the dual chemically treated
pulp fibers is about 0.1 kilogram per metric ton or greater, and
the amount of unretained first water insoluble chemical additive in
the water is between 0 and about 75 percent of the applied amount
of the first water insoluble chemical additive when the dual
chemically treated pulp fibers are exposed to a liquid.
71. The method of claim 68, wherein the amount of the second water
insoluble chemical additive retained by the dual chemically treated
pulp fibers is about 0.1 kilogram per metric ton or greater, and
the amount of unretained second water insoluble chemical additive
in the water is between 0 and about 75 percent of the applied
amount of the second water insoluble chemical additive when the
dual chemically treated pulp fibers are exposed to a liquid.
72. The method of claim 68, wherein the amount of the first water
insoluble chemical additive retained by the dual chemically treated
pulp fibers is about 0.1 kilograms per metric ton or greater, and
the amount of unretained first water insoluble chemical additive in
the water is between 0 and about 75 percent of the applied amount
of the first water insoluble chemical additive when the dual
chemically treated pulp fibers are exposed to a liquid and wherein
the amount of the second water insoluble chemical additive retained
by the dual chemically treated pulp fibers is about 0.1 kilogram
per metric ton or greater, and the amount of unretained second
water insoluble chemical additive in the water is between 0 and
about 75 percent of the applied amount of the second water
insoluble chemical additive when the dual chemically treated pulp
fibers are exposed to a liquid.
73. A wet-wipe product made using the method of claim 64.
Description
BACKGROUND OF THE INVENTION
[0001] Fibrous non-woven materials and fibrous non-woven composite
materials are widely used as products, or as components of
products, such as wet-wipes because they may be manufactured
inexpensively and made to have specific characteristics. These
products may be manufactured so inexpensively that they may be
viewed as disposable, as opposed to reusable.
[0002] One approach to making fibrous non-woven composite materials
for wet-wipes is the use of homogeneous mixtures of materials such
as air laid webs of fibers mixed with cellulosic fibers or another
absorbent material. Other wet-wipes have been prepared by joining
different types of non-woven materials in a laminate or formed as a
layered structure. These products may be prepared from plastic
materials such as plastic sheets, films and non-woven webs,
prepared by extrusion processes such as, for example, slot film
extrusion, blown bubble film extrusion, meltblowing of non-woven
webs and spin bonding.
[0003] The non-woven materials and laminated non-woven materials
that are useful for consumer products should meet minimum product
standards for strength, moisture level, size, flexibility,
thickness, softness and texture. However, if one of these
parameters is changed this may affect another of the parameters.
Thus, a goal for these materials is to produce a product that may
mimic a soft cloth-like feel or at least get closer to a soft
cloth-like feel than has been previously possible while still
maintaining acceptable strength and other characteristics.
[0004] Such a soft cloth-like feel is often characterized by, among
other things, one or more of the following: thickness, bulk
density, flexibility, texture, softness, density, and durability of
the non-woven materials. These materials are suitable for
disposable products such as, for example, disposable diapers,
disposable tissues and disposable wipes, for example, disposable
wet-wipes.
[0005] In the manufacture of products containing pulp fibers, it is
often desirable to enhance physical and/or optical properties of
the pulp fibers and/or fibrous nonwoven material by the addition of
chemical additives onto the pulp fibers and/or fibrous nonwoven
material. Typically, chemical additives such as softeners,
colorants, brighteners, strength agents, etc. are added to the
fiber slurry upstream of the headbox in a paper making machine
during the manufacturing or converting stages of production to
impart certain attributes to the finished product. These chemical
additives are usually mixed in a stock chest or stock line where
the fiber slurry has a fiber consistency of from between about 0.15
to about 5 percent or spraying the wet or dry paper or tissue
during production.
[0006] One disadvantage of adding a chemical additive at each
manufacturing, such as papermaking, machine is that the
manufacturer has to install equipment on each paper machine to
accomplish the chemical additive addition. This, in many cases, is
a costly proposition. In addition, the uniformity of the finished
product coming off of each manufacturing machine may vary depending
upon how the chemical additive was added, variations in chemical
additive uniformity and concentrations, the exact point of chemical
additive introduction, water chemistry differences among the
manufacturing machines as well as personnel and operational
differences of each manufacturing machine.
[0007] Another difficulty associated with wet end chemical additive
in a solution addition, such as to a pulp slurry, is that the water
soluble or water dispersible chemical additives are suspended in
water and are not completely adsorbed or retained onto the fibers
prior to formation of the wet mat. To improve adsorption of wet end
chemical additives, the chemical additives are often modified with
functional groups to impart an electrical charge when in water. The
electrokinetic attraction between charged chemical additives and
the anionically charged fiber surfaces aids in the deposition and
retention of chemical additives onto the fibers. Nevertheless, the
amount of the chemical additive that can be adsorbed or retained in
the manufacturing machine wet end generally follows an adsorption
curve exhibiting diminishing incremental adsorption with increasing
concentration, similar to that described by Langmuir. As a result,
the adsorption of water soluble or water dispersible chemical
additives may be significantly less than 100 percent, particularly
when trying to achieve high chemical additive loading levels. The
use of water insoluble chemical additives in the water systems of
manufacturing processes is even more problematic and typically
provides even poorer loading levels. Water insoluble chemical
additives or water nondispersible chemical additives cannot
typically be used in such water systems unless in the form of an
emulsion.
[0008] Consequently, at any chemical addition level, and
particularly at high addition levels, a fraction of the chemical
additive is retained on the fiber surface. The remaining fraction
of the chemical additive remains dissolved or dispersed in the
suspending water phase. These unadsorbed or unretained chemical
additives can cause a number of problems in the manufacturing
process. The exact nature of the chemical additive will determine
the specific problems that may arise, but a partial list of
problems that may result from unadsorbed or unretained chemical
additives includes: foam, deposits, contamination of other fiber
streams, poor fiber retention on the machine, compromised chemical
layer purity in multi-layer products, dissolved solids build-up in
the water system, interactions with other process chemicals, felt
or fabric plugging, excessive adhesion or release on dryer
surfaces, physical property variability in the finished
product.
[0009] Therefore, what is lacking and needed in the art is a
fibrous non-woven material or a fibrous non-woven composite
material containing pulp fibers wherein water insoluble chemical
additives are applied onto the pulp fibers, providing more
consistent water insoluble chemical additive additions to the pulp
fiber and a reduction or elimination of unretained water insoluble
chemical additives in the process water on a paper machine.
[0010] The present invention minimizes the associated manufacturing
and finished product quality problems that would otherwise occur
with conventional wet end chemical addition at the manufacturing
machine.
Definitions
[0011] For the purposes of the present application, the following
terms shall have the following meanings:
[0012] As used herein the term "chemical additive" refers to a
single treatment compound or to a mixture of treatment compounds.
It is also understood that a chemical additive used in the present
invention may be an adsorbable chemical additive.
[0013] As used herein the term "non-woven web" means a structure or
a web of material which has been formed without use of weaving
processes to produce a structure of individual fibers or threads
which are intermeshed, but not in an identifiable, repeating
manner. Non-woven webs have been, in the past, formed by a variety
of conventional processes such as, for example, meltblowing
processes, spinbonding processes, film aperturing processes and
staple fiber carding processes.
[0014] As used herein, the term "meltblown fibers" means fibers
formed by extruding a molten thermoplastic material through a
plurality of fine, usually circular, die capillaries as molten
threads or filaments into a high velocity gas (e.g. air) stream
which attenuates the filaments of molten thermoplastic material to
reduce their diameter, which maybe to microfiber diameter.
Thereafter, the meltblown fibers are carried by the high velocity
gas stream and are deposited on a collecting surface to form a web
of randomly disbursed meltblown fibers. Such a process is
disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin.
[0015] As used herein, the term "spunbonded fibers" refers to small
diameter fibers which are formed by extruding a molten
thermoplastic polymeric material as filaments from a plurality of
fine, usually circular, capillaries of a spinnerette with the
diameter of the extruded filaments then being rapidly reduced as
by, for example, eductive drawing or other well-known spun-bonding
mechanisms. The production of spun-bonded non-woven webs is
illustrated in patents such as, for example, in U.S. Pat. No.
4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner
et al.
[0016] As used herein, the term "coform" means a non-woven
composite material of air-formed matrix material comprising
thermoplastic polymeric meltblown fibers such as, for example,
microfibers having an average fiber diameter of less than about 10
microns, and a multiplicity of individualized absorbent fibers such
as, for example, wood pulp fibers disposed throughout the matrix of
polymer microfibers and engaging at least some of the microfibers
to space the microfibers apart from each other. The absorbent
fibers are interconnected by and held captive within the matrix of
microfibers by mechanical entanglement of the microfibers with the
absorbent fibers, the mechanical entanglement and interconnection
of the microfibers and absorbent fibers alone forming a coherent
integrated fibrous structure. These materials are prepared
according to the descriptions in U.S. Pat. No. 4,100,324 to
Anderson et al. U.S. Pat. No. 5,508,102 to Georger et al. and U.S.
Pat. No. 5,385,775 to Wright.
[0017] As used herein, the term "microfibers" means small diameter
fibers having an average diameter not greater than about 100
microns, for example, having an average diameter of from about 0.5
microns to about 50 microns, or more particularly, microfibers may
have an average diameter of from about 4 microns to about 40
microns.
[0018] As used herein, the term "autogenous bonding" means bonding
provided by fusion and/or self-adhesion of fibers and/or filaments
without an applied external adhesive or bonding agent. Autogenous
bonding may be provided by contact between fibers and/or filaments
while at least a portion of the fibers and/or filaments are
semi-molten or tacky. Autogenous bonding may also be provided by
blending a tackifying resin with the thermoplastic polymers used to
form the fibers and/or filaments. Fibers and/or filaments formed
from such a blend may be adapted to self-bond with or without the
application of pressure and/or heat. Solvents may also be used to
cause fusion of fibers and filaments which remains after the
solvent is removed.
[0019] As used herein, the term "machine direction (MD)" refers to
the direction of travel of the forming surface onto which fibers
are deposited during formation of a non-woven fibrous web.
[0020] As used herein, the term "cross-machine direction (CD)"
refers to the direction which is essentially perpendicular to the
machine direction defined above.
[0021] As used herein, the term "tensile strength" refers to the
maximum load or force (i.e., peak load) encountered while
elongating the sample to break. Measurements of peak load are made
in the machine and cross-machine directions using wet samples.
[0022] As used herein, the term "wet-wipe" refers to a fibrous
sheet which, during its manufacture, has a liquid applied thereto
so that the liquid may be retained on or within the fibrous sheet
until its utilization by a consumer. The liquid may include a
fragrance and/or an emollient and may serve to aid the fibrous
sheet in retention of materials which are to be wiped up during its
utilization.
[0023] As used herein, the terms "fibrous non-woven material" and
"fibrous non-woven composite material" refer to material that may
be used as the sheet or substrate for a consumer product, such as a
wet-wipe or wipe-type product, which has a liquid applied thereto
that may be retained on or within the fibrous sheet until it is
utilized by a consumer.
[0024] As used herein, the terms "stretch-bonded laminate" or
"composite elastic material" refers to a fabric material having at
least one ply of non-woven web being elastic and at least one ply
of the non-woven web being non-elastic, e.g., a gatherable ply. The
elastic non-woven web ply(s) are joined or bonded in at least two
locations to the non-elastic non-woven web ply(s). Preferably, the
bonding is at intermittent bonding points or areas while the
non-woven web ply (s) are in juxtaposed configuration and while the
elastic non-woven web ply(s) have a tensioning force applied
thereto in order to bring the elastic non-woven web to a stretched
condition. Upon removal of the tensioning force after joining of
the web plies, an elastic non-woven web ply will attempt to recover
to its unstretched condition and will thereby gather the
non-elastic non-woven web ply between the points or areas of
joining of the two plies. The composite material is elastic in the
direction of stretching of the elastic ply during joining of the
plies and may be stretched until the gathers of the non-elastic
non-woven web or film ply have been removed. A stretch-bonded
laminate may include more than two plies. For example, the elastic
non-woven web or film may have a non-elastic non-woven web ply
joined to both of its sides while it is in a stretched condition so
that a three ply non-woven web composite is formed having the
structure of gathered non-elastic (non-woven web or film)/elastic
(non-woven web or film)/gathered non-elastic (non-woven web or
film). Yet other combinations of elastic and non-elastic plies may
also be utilized. Such composite elastic materials are disclosed,
for example, by U.S. Pat. No. 4,720,415 to Vander Wielen et al.,
and U.S. Pat. No. 5,385,775 to Wright.
[0025] As used herein "thermal point bonding" involves passing a
material such as two or more webs of fibers to be bonded between a
heated calendar roll and an anvil roll. The calender roll is
usually, though not always, patterned in some way so that the
entire fabric is not bonded across its entire surface, and the
anvil roll is usually flat or crowned. As a result, various
patterns for calender rolls have been developed for functional as
well as aesthetic reasons. In one embodiment of this invention the
bond pattern allows void spaces in the machine direction to allow a
gatherable ply to gather when the web retracts.
[0026] As used herein the term "unretained" refers to any portion
of the chemical additive that is not retained by the pulp fiber and
thus remains suspended in the process water.
[0027] As used herein the term "web-forming apparatus" includes
fourdrinier former, twin wire former, cylinder machine, press
former, crescent former, and the like used in the pulp stage known
to those skilled in the art.
[0028] As used herein the term "water" refers to water or a
solution containing water and other treatment additives desired in
the manufacturing process or in the finished wet-wipe product.
[0029] As used herein the term "superabsorbent" refers to a water
swellable, substantially insoluble organic or inorganic material
capable of absorbing at least 10 times its weight of an aqueous
solution containing 0.9 wt % of sodium chloride.
[0030] As used herein the term "palindromic" means a multi-ply
laminate, for example a stretch-bonded laminate, which is
substantially symmetrical. Examples of palindromic laminates could
have ply configurations of A/B/A, A/B/B/A, A/A/B/B/A/A, A/B/C/B/A,
and the like. Examples of non-palindromic ply configurations would
include A/B/C, A/B/C/A, A/B/C/D, etc.
[0031] As used herein the term "polymer" generally includes, but is
not limited to, homopolymers, copolymers, such as, for example,
block, graft, random and alternating copolymers, terpolymers, etc.
and blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the material. These configurations
include, but are not limited to, isotactic, syndiotactic and random
symmetries.
[0032] As used herein the term "pulp fiber" is used herein to
broadly include fiber used in writing paper, printing paper,
wrapping paper, sanitary paper, and industrial papers, newsprint,
linerboard, tissue, bath tissue, facial tissue, napkins, wipers,
wet-wipes, towels, absorbent pads, intake webs in absorbent
articles such as diapers, bed pads, meat and poultry pads, feminine
care pads, and the like made in accordance with any conventional
process for the production of such products. With regard to the use
of the term "pulp fiber" as used herein includes any fibers used in
any fibrous web containing cellulosic fibers alone or in
combination with other fibers, natural or synthetic. It may be
plied or unplied, layered or unlayered, creped or uncreped, and may
consist of a single ply or multiple plies. In addition, the fibrous
web may contain reinforcing fibers for integrity and strength.
[0033] As used herein the term "softening agent" refers to any
chemical additive that may be incorporated into products such as
tissue to provide improved tactile feel and reduce stiffness of the
product. A softening agent may be selected from the group
consisting of quaternary ammonium compounds, quaternized protein
compounds, phospholipids, polysiloxane compounds, quaternized,
hydrolyzed wheat protein/dimethicone phosphocopolyol copolymer,
organoreactive polysilxanes, polyhydroxy compounds, and silicone
glycols. These chemical additives may also act to reduce the
stiffness of the product or may act solely to improve the surface
characteristics of product, such as by reducing the coefficient of
friction between the surface of the product and the hand.
[0034] As used herein the term "dye" refers to any chemical that
may be incorporated into fibrous non-woven materials or fibrous
non-woven composite material based products, such as wet-wipes,
bathroom tissue, facial tissue, paper towels, and napkins, to
impart a color. Depending on the nature of the chemical, dyes may
be classified as acid dyes, basic dyes, direct dyes, cellulose
reactive dyes, or pigments. All classifications are suitable for
use in conjunction with the present invention.
[0035] As used herein the term "polyhydroxy compounds" refers to
compounds selected from the group consisting of glycerol,
sorbitols, polyglycerols having a weight average molecular weight
of from about 150 to about 800, polyoxyethylene glycols and
polyoxypropylene glycols having a weight average molecular weight
from typically about 200 to about 10,000, more typically about 200
to about 4,000.
[0036] As used herein the term "water soluble" refers to solids or
liquids that will form a solution in water, and the term "water
dispersible" refers to solids or liquids of colloidal size or
larger that may be dispersed into an aqueous medium. As used herein
the term "water insoluble" refers to solids or liquids that will
not form a solution in water.
[0037] As used herein the term "bonding agent" refers to any
chemical that may be incorporated into tissue to increase or
enhance the level of interfiber or intrafiber bonding in the sheet.
The increased bonding may be either ionic, Hydrogen or covalent in
nature. It is understood that a bonding agent refers to both dry
and wet strength enhancing chemical additives.
SUMMARY OF THE INVENTION
[0038] The problem of a fibrous non-woven material lacking desired
characteristics or properties, such as softness or cloth-like feel
may be addressed by the application of water insoluble chemical
additives to pulp fibers at high and/or consistent levels with
little or no migration of the water insoluble chemical additive
into the process water or product solutions.
[0039] It has now been discovered that water insoluble chemical
additives can be applied to pulp fibers at high and/or consistent
levels with reduced amounts of unretained water insoluble chemical
additives present in the manufacturing process water, such as
papermaking, after the treated pulp fiber has been exposed to a
liquid, such as water. This is accomplished by treating a fibrous
web prior to the finishing operation at a pulp mill with a water
insoluble chemical additive, completing the finishing operation,
and using the finished chemically treated pulp in the production of
a fibrous non-woven material or fibrous non-woven composite
material. As used herein, the term "fibrous non-woven material" is
understood to include fibrous non-woven composite material(s).
[0040] Hence in one aspect, the invention resides in a method for
preparing chemically treated pulp fibers contained in a fibrous
non-woven material. The method comprises creating a fiber slurry
comprising process water and virgin pulp fibers. The fiber slurry
is transported to a web-forming apparatus of a pulp sheet machine
and formed into a wet fibrous web. The wet fibrous web is dried to
a predetermined consistency thereby forming a dried fibrous web.
The dried fibrous web is treated with a water insoluble chemical
additive thereby forming a chemically treated dried fibrous web
containing chemically treated pulp fibers wherein the chemically
treated pulp fibers have an increased or improved level of chemical
retention of the water insoluble chemical additive and have a level
of chemical retention of the water insoluble chemical additive is
between about 25 to about 100 percent retention of the applied
amount of the water insoluble chemical additive when the chemically
treated pulp fibers are exposed to a liquid, such as water or
product solution. The chemically treated pulp fibers are used to
form the fibrous non-woven material. The level of chemical
retention of the water insoluble chemical additive may range from
between about 60 to about 100 percent or between about 80 to about
100 percent retention of the water insoluble chemical additive. The
improved level of chemical retention of the water insoluble
chemical additive, measured as the change in the level of chemical
retention of adding by typical wet-end addition, may range from a
lower limit of about 5 percent, about 15 percent, about 25 percent,
about 35 percent, about 45 percent, about 55 percent, about 65
percent, and about 75 percent to a higher limit of about 25
percent, about 35 percent, about 45 percent, about 55 percent,
about 65 percent, about 75 percent, about 85 percent, about 95
percent, and about 100 percent retention of the water insoluble
chemical additive. It is understood that the value for the lower
limit is less than the value for the upper limit. The chemically
treated pulp fiber may be then used in a separate process to
produce paper products.
[0041] In another aspect, the invention resides in a method for
applying a water insoluble chemical additive to a fibrous non-woven
material. The method comprises mixing pulp fibers with process
water to form a fiber slurry. The fiber slurry is transported to a
web-forming apparatus of a pulp sheet machine and forming a wet
fibrous web. The wet fibrous web is dewatered to a predetermined
consistency thereby forming a dewatered fibrous web. A water
insoluble chemical additive is applied to the dewatered fibrous
web, thereby forming a chemically treated dewatered fibrous web
containing chemically treated pulp fibers wherein the chemically
treated pulp fibers have an increased or improved level of chemical
retention of the water insoluble chemical additive wherein the
level of chemical retention of the water insoluble chemical
additive is between about 25 to about 100 percent of the applied
amount of the water insoluble chemical additive when the chemically
treated pulp fibers are exposed to a liquid. The chemically treated
pulp fibers are used to form the fibrous non-woven material. The
level of chemical retention of the water insoluble chemical
additive may range from between about 60 to about 100 percent or
between about 80 to about 100 percent retention of the water
insoluble chemical additive. The improved level of chemical
retention of the water insoluble chemical additive, measured as the
change in the level of chemical retention of adding by typical
wet-end addition, may range from a lower limit of about 5 percent,
about 15 percent, about 25 percent, about 35 percent, about 45
percent, about 55 percent, about 65 percent, and about 75 percent
to a higher limit of about 25 percent, about 35 percent, about 45
percent, about 55 percent, about 65 percent, about 75 percent,
about 85 percent, about 95 percent, and about 100 percent retention
of the water insoluble chemical additive. It is understood that the
value for the lower limit is less than the value for the upper
limit.
[0042] According to another embodiment of the present invention is
a method for applying a water insoluble chemical additive to the
pulp fibers to be incorporated into a fibrous non-woven material
during the pulp processing stage. During the pulp processing stage,
upstream of a manufacturing machine, one can obtain chemically
treated pulp fiber. Furthermore, the chemically treated pulp fiber
can be transported to several different manufacturing machines that
may be located at various sites, and the quality of the finished
product from each manufacturing machine will be more consistent.
Also, by chemically treating the pulp fiber before the pulp fiber
is made available for use on multiple manufacturing machines or
multiple runs on a manufacturing machine, the need to install
equipment at each manufacturing machine for the water insoluble
chemical additive addition can be eliminated.
[0043] The method of the present invention allows for the
production or processing of pulp fibers also enables higher and
more uniform concentrations of the water insoluble chemical
additive to be retained by the pulp fibers while at the same time
maintaining significantly lower levels of unretained water
insoluble chemical additive in the water phase of a manufacturing
machine compared to paper machine wet end chemical additive
additions.
[0044] The consistency of the dried fibrous web is from about 65 to
about 100 percent. In other embodiments, the consistency of the
dried fibrous web is from about 80 to about 100 percent or from
about 85 to about 95 percent. The consistency of the dewatered
fibrous web is from about 20 to about 65 percent. In other
embodiments, the consistency of the dewatered fibrous web is from
about 40 to about 65 percent or from about 50 to about 65 percent.
The consistency of the crumb form is from about 20 to about 85
percent. In other embodiments, the consistency of the crumb form is
from about 30 to about 60 percent or from about 30 to about 45
percent.
[0045] The present method allows for the production of pulp fibers
to be incorporated into a fibrous non-woven material that is useful
for making products such as wet-wipe products. One aspect of the
present invention is a uniform supply of chemically treated pulp
fiber, replacing the need for costly and variable chemical
treatments at one or more manufacturing machines. Another aspect of
the invention resides in a pulp fiber that has a higher water
insoluble chemical additive loading than could otherwise be
achieved in combination with either no or a relatively low level of
unretained water insoluble chemical additive in the process water
on a manufacturing machine. This is because water insoluble
chemical additive loading via wet end addition is often limited by
the level of unadsorbed or unretained water insoluble chemical
additive and/or contact time, as well as its associated processing
difficulties such as foam, deposits, chemical interactions, felt
plugging, excessive dryer adhesion or release or a variety of
product physical property control issues caused by the presence of
unadsorbed or unretained water insoluble chemical additive in the
process water on the manufacturing machines. Another aspect of the
invention is the ability to deliver pulp fiber treated with water
insoluble chemical additives that would not otherwise be retained
when added in the wet end of a manufacturing operation or product
solutions.
[0046] According to one embodiment of the present invention, the
method comprises adding at least a first chemical additive to pulp
fiber. Pulp fibers are mixed with process water thereby forming a
fiber slurry. The fiber slurry is transported to a web-forming
apparatus of a pulp sheet machine. The fiber slurry is dewatered
thereby forming a crumb pulp. A water insoluble chemical additive
is applied to the crumb pulp thereby forming a chemically treated
crumb pulp containing chemically treated pulp fibers. The
chemically treated pulp fibers have an increased or improved level
of chemical retention of the water insoluble chemical additive and
have the level of chemical retention of the water insoluble
chemical additive that is between about 25 to about 100 percent
retention of the applied amount of the water insoluble chemical
additive when the chemically treated pulp fibers are exposed to a
liquid. The chemically treated pulp having the water insoluble
chemical additive retained thereon is used to form a fibrous
non-woven material. The level of chemical retention of the water
insoluble chemical additive may range from between about 60 to
about 100 percent or between about 80 to about 100 percent
retention of the water insoluble chemical additive. The improved
level of chemical retention of the water insoluble chemical
additive, measured as the change in the level of chemical retention
of adding by typical wet-end addition, may range from a lower limit
of about 5 percent, about 15 percent, about 25 percent, about 35
percent, about 45 percent, about 55 percent, about 65 percent, and
about 75 percent to a higher limit of about 25 percent, about 35
percent, about 45 percent, about 55 percent, about 65 percent,
about 75 percent, about 85 percent, about 95 percent, and about 100
percent retention of the water insoluble chemical additive. It is
understood that the value for the lower limit is less than the
value for the upper limit.
[0047] Another aspect of the present invention resides in a method
for applying water insoluble chemical additives to pulp fiber. The
method comprises creating a fiber slurry comprising process water
and pulp fibers. The fiber slurry is transported to a web-forming
apparatus of a pulp sheet machine and forming a wet fibrous web.
The wet fibrous web is dewatered to a predetermined consistency
thereby forming a dewatered fibrous web. A first water insoluble
chemical additive is applied to the dewatered fibrous web to form a
chemically treated dewatered fibrous web of chemically treated pulp
fibers. A second water insoluble chemical additive is applied to
the chemically treated dewatered fibrous web thereby forming a dual
chemically treated dewatered fibrous web containing dual chemically
treated pulp fibers wherein the dual chemically treated pulp fibers
have an improved level of chemical retention of the first water
insoluble chemical additive and have a level of chemical retention
of the first water insoluble chemical additive that is between
about 25 to about 100 percent retention of the applied amount of
the first water insoluble chemical additive when the dual
chemically treated pulp fibers are exposed to a liquid and wherein
the dual chemically treated pulp fibers have an improved level of
chemical retention of the second water insoluble chemical additive
and have a level of chemical retention of the second water
insoluble chemical additive that is between about 25 to about 100
percent retention of the applied amount of the second water
insoluble chemical additive when the dual chemically treated pulp
fibers are exposed to a liquid. The chemically treated pulp having
the first and second water insoluble chemical additives retained
thereon is used to form a fibrous non-woven material. The level of
chemical retention of the first and/or second water insoluble
chemical additive may range from between about 60 to about 100
percent or between about 80 to about 100 percent retention of the
applied amount of the first and/or second water insoluble chemical
additive. The improved level of chemical retention of the first
and/or second water insoluble chemical additive, measured as the
change in the level of chemical retention of adding by typical
wet-end addition, may range from a lower limit of about 5 percent,
about 15 percent, about 25 percent, about 35 percent, about 45
percent, about 55 percent, about 65 percent, and about 75 percent
to a higher limit of about 25 percent, about 35 percent, about 45
percent, about 55 percent, about 65 percent, about 75 percent,
about 85 percent, about 95 percent, and about 100 percent retention
of the first and/or second water insoluble chemical additive,
respectively. It is understood that the value for the lower limit
is less than the value for the upper limit.
[0048] Another aspect of the present invention resides in a method
for applying water insoluble chemical additives to pulp fiber. The
method comprises mixing pulp fibers with process water to form a
fiber slurry. The fiber slurry is transported to a web-forming
apparatus of a pulp sheet machine and forming a wet fibrous web.
The wet fibrous web is dewatered to a predetermined consistency
thereby forming a dewatered fibrous web. The dewatered fibrous web
is dried to a predetermined consistency thereby forming a dried
fibrous web. A first water insoluble chemical additive is applied
to the dried fibrous web and applying a second water insoluble
chemical additive to the dried fibrous web, thereby forming a dual
chemically treated dewatered fibrous web containing dual chemically
treated pulp fibers wherein the dual chemically treated pulp fibers
have an improved level of chemical retention of the first water
insoluble chemical additive and have a level of chemical retention
of the first water insoluble chemical additive is between about 25
to about 100 percent retention of the applied amount of the first
water insoluble chemical additive when the dual chemically treated
pulp fibers are exposed to a liquid and wherein the dual chemically
treated pulp fibers have an improved level of chemical retention of
the second water insoluble chemical additive and have a level of
chemical retention of the second water insoluble chemical additive
is between about 25 to about 100 percent retention of the applied
second water insoluble chemical additive when the dual chemically
treated pulp fibers are exposed to a liquid. The chemically treated
pulp having the first and second water insoluble chemical additives
retained thereon is used to form a fibrous non-woven material. The
level of chemical retention of the first and/or second water
insoluble chemical additive may range from between about 60 to
about 100 percent or between about 80 to about 100 percent
retention of the applied amount of the first and/or second water
insoluble chemical additive. The improved level of chemical
retention of the first and/or second water insoluble chemical
additive, measured as the change in the level of chemical retention
of adding by typical wet-end addition, may range from a lower limit
of about 5 percent, about 15 percent, about 25 percent, about 35
percent, about 45 percent, about 55 percent, about 65 percent, and
about 75 percent to a higher limit of about 25 percent, about 35
percent, about 45 percent, about 55 percent, about 65 percent,
about 75 percent, about 85 percent, about 95 percent, and about 100
percent retention of the first and/or second water insoluble
chemical additive, respectively. It is understood that the value
for the lower limit is less than the value for the upper limit. A
finished product having enhanced qualities due to the retention of
the chemical additive by the pulp fibers may be produced.
[0049] Another aspect of the present invention resides in a method
for applying water insoluble chemical additives to pulp fiber. The
method comprises mixing pulp fibers with process water to form a
fiber slurry. The fiber slurry is transported to a web-forming
apparatus of a pulp sheet machine and forming a wet fibrous web.
The wet fibrous web is dewatered to a predetermined consistency
thereby forming a dewatered fibrous web. Applying a first water
insoluble chemical additive to the dewatered fibrous web to the
dewatered fibrous web thereby forming a chemically treated
dewatered fibrous web. The chemically treated dewatered fibrous web
is dried to a predetermined consistency thereby forming a
chemically treated dried fibrous web. A second water insoluble
chemical additive is applied to the chemically treated dried
fibrous web, thereby forming a dual chemically treated dried
fibrous web containing dual chemically treated pulp fibers wherein
the dual chemically treated pulp fibers have an improved level of
chemical retention of the first water insoluble chemical additive
and have a level of chemical retention of the first water insoluble
chemical additive that is between about 25 to about 100 percent
retention of the applied amount of the first water insoluble
chemical additive when the dual chemically treated pulp fibers are
exposed to a liquid and wherein the dual chemically treated pulp
fibers have an improved level of chemical retention of the second
water insoluble chemical additive and have a level of chemical
retention of the second water insoluble chemical additive that is
between about 25 to about 100 percent retention of the applied
amount of the second water insoluble chemical additive when the
dual chemically treated pulp fibers are exposed to a liquid. The
chemically treated pulp having the first and second water insoluble
chemical additives retained thereon is used to form a fibrous
non-woven material. The level of chemical retention of the first
and/or second water insoluble chemical additive may range from
between about 60 to about 100 percent or between about 80 to about
100 percent retention of the applied amount of the first and/or
second water insoluble chemical additive. The improved level of
chemical retention of the first and/or second water insoluble
chemical additive, measured as the change in the level of chemical
retention of adding by typical wet-end addition, may range from a
lower limit of about 5 percent, about 15 percent, about 25 percent,
about 35 percent, about 45 percent, about 55 percent, about 65
percent, and about 75 percent to a higher limit of about 25
percent, about 35 percent, about 45 percent, about 55 percent,
about 65 percent, about 75 percent, about 85 percent, about 95
percent, and about 100 percent retention of the first and/or second
water insoluble chemical additive, respectively. It is understood
that the value for the lower limit is less than the value for the
upper limit. A finished product having enhanced qualities due to
the retention of the chemical additive by the pulp fibers may be
produced.
[0050] The present invention is particularly useful for adding
water insoluble chemical additives such as softening agents to the
pulp fibers, allowing for the less problematic and lower cost
production of finished products having enhanced qualities provided
by the retained water insoluble chemical additives by the pulp
fibers.
[0051] Hence, another aspect of the present invention resides in
fibrous non-woven materials and products made therefrom formed from
pulp fibers that have been chemically treated to minimize the
amount of residual, unretained water insoluble chemical additives
in the process water on a manufacturing machine or in the product
solutions.
[0052] The method for applying water insoluble chemical additives
to the pulp fibers may be used in a wide variety of pulp finishing
processing, including dry lap pulp, wet lap pulp, crumb pulp, and
flash dried pulp operations. By way of illustration, various pulp
finishing processes (also referred to as pulp processing) are
disclosed in Pulp and Paper Manufacture: The Pulping of Wood,
2.sup.nd Ed., Volume 1, Chapter 12. Ronald G. MacDonald, editor,
which is incorporated by reference. Various methods may be used to
apply the water insoluble chemical additives in the present
invention, including, but not limited to: spraying, dipping,
coating, foaming, printing, size pressing, or any other method
known in the art.
[0053] In addition, in situations where more than one water
insoluble chemical additive is to be employed, the water insoluble
chemical additives may be added to the fibrous web in sequence to
reduce interactions between the water insoluble chemical
additives.
[0054] Many pulp fiber types may be used for the present invention
including hardwood or softwoods, straw, flax, milkweed seed floss
fibers, abaca, hemp, kenaf, bagasse, cotton, reed, and the like.
All known papermaking fibers may be used, including bleached and
unbleached fibers, fibers of natural origin (including wood fiber
and other cellulose fibers, cellulose derivatives, and chemically
stiffened or crosslinked fibers), some component portion of
synthetic fiber (synthetic papermaking fibers include certain forms
of fibers made from polypropylene, acrylic, aramids, acetates, and
the like), virgin and recovered or recycled fibers, hardwood and
softwood, and fibers that have been mechanically pulped (e.g.,
groundwood), chemically pulped (including but not limited to the
kraft and sulfite pulp processings), thermomechanically pulped,
chemithermomechanically pulped, and the like. Mixtures of any
subset of the above mentioned or related fiber classes may be used.
The pulp fibers can be prepared in a multiplicity of ways known to
be advantageous in the art. Useful methods of preparing fibers
include dispersion to impart curl and improved drying properties,
such as disclosed in U.S. Pat. No. 5,348,620 issued Sep. 20, 1994
and U.S. Pat. No. 5,501,768 issued Mar. 26, 1996, both to M. A.
Hermans et al. and U.S. Pat. No. 5,656,132 issued Aug. 12, 1997 to
Farrington, Jr. et al.
[0055] According to the present invention, the chemical treatment
of the pulp fibers may occur prior to, during, or after the drying
phase of the pulp processing. The generally accepted methods of
drying include flash drying, can drying, flack drying, through air
drying, Infra-red drying, fluidized bed, or any method of drying
known in the art. The present invention may also be applied to wet
lap pulp processes without the use of dryers.
[0056] Numerous features and advantages of the present invention
will appear from the following description. In the description,
reference is made to the accompanying drawings which illustrate
preferred embodiments of the invention. Such embodiments do not
represent the full scope of the invention. Reference should
therefore be made to the claims herein for interpreting the full
scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 depicts a schematic process flow diagram of a method
according to the present invention for treating pulp fibers with a
single water insoluble chemical additive.
[0058] FIG. 2 depicts a schematic process flow diagram of a method
according to the present invention for treating pulp fibers with
multiple water insoluble chemical additives.
[0059] FIG. 3 depicts a schematic process flow diagram of a method
of making a fibrous non-woven material.
[0060] FIG. 4 depicts a fluidized bed apparatus for applying water
insoluble chemical additives to pulp fibers.
[0061] FIG. 5 depicts a fluidized bed apparatus for applying water
insoluble chemical additives to pulp fibers.
DETAILED DESCRIPTION
[0062] The present invention provides a fibrous non-woven material
or fibrous non-woven composite material adapted to provide improved
softness and cloth-like feel in a finished product, such as a
wet-wipe. The feel of a wet-wipe is often characterized by one or
more of the following attributes of the fibrous non-woven materials
that comprise them: thickness, bulk density, flexibility, texture,
softness, and durability. In preparing a wet-wipe having a soft
cloth-like feel, it is important to balance the properties of the
non-woven material or non-woven composite material, e.g., cup
crush, density, and tensile strength. However, this is a difficult
task because these properties may be interdependent, i.e., changing
one property may affect another property (and the overall feel of
the wet-wipe). Typically, when the basis weight is decreased, the
cup-crush is decreased, and tensile strength is decreased. When the
basis weight is increased then the reverse changes occur. Thus,
when a property is varied, to enhance the softness, careful
attention should be paid to the results obtained to avoid a
resultant product having less desirable overall properties. It is
understood that the fibrous non-woven material or fibrous non-woven
composite material may be layered and that discussions regarding a
ply or plies may also be applied to a layer or layers.
[0063] The wet-wipes of the present invention include at least one
ply of fibrous non-woven material or fibrous non-woven composite
material. The preferred CD tensile strength of the fibrous
non-woven material or the fibrous non-woven composite material of
the wet-wipe is of greater than about 0.70 lbs. A more preferred CD
tensile strength is of greater than about 0.75 lbs. A slightly more
preferred CD tensile strength is of greater than about 0.80 lbs. A
yet more preferred CD tensile strength is of greater than about
0.85 lbs. A much more preferred CD tensile strength is of greater
than about 0.90 lbs. A very much more preferred CD tensile strength
is of greater than about 0.95 lbs. The most preferred CD tensile
strength is of greater than about 1.0 lbs.
[0064] The basis weight (in grams per square meter, g/m.sup.2 or
gsm) of the fibrous non-woven material of the wet-wipe is
calculated by dividing the dry weight by the area (in square
meters). The density of the fibrous non-woven material or fibrous
non-woven composite material of the wet-wipe, as used herein, is a
"wet density" and is calculated as the basis weight (in grams per
square meter, g/m.sup.2 or gsm) divided by the thickness of the
wet-wipe after wetting with the solution.
[0065] The wet-wipes of the present invention comprise a fibrous
non-woven material or a fibrous non-woven composite material and a
liquid. The liquid may be any solution which may be absorbed into
the wet-wipe composite elastic material and may include any
suitable components which provide the desired wiping properties.
For example, the components may include water, emollients,
surfactants, fragrances, preservatives, chelating agents, pH
buffers or combinations thereof as are well known to those skilled
in the art. The liquid may also contain lotions and/or
medicaments.
[0066] The amount of liquid contained within each wet-wipe may vary
depending upon the type of material being used to provide the
wet-wipe, the type of liquid being used, the type of container
being used to store the wet-wipes, and the desired end use of the
wet-wipe. Generally, each wet-wipe may contain from about 150 to
about 600 weight percent and preferably from about 250 to about 450
weight percent liquid based on the dry weight of the wipe for
improved wiping. In a more preferred aspect, the amount of liquid
contained within the wet-wipe is from about 300 to about 400 weight
percent and desirably about 330 weight percent based on the dry
weight of the wet-wipe. If the amount of liquid is less than the
above-identified ranges, the wet-wipe may be too dry and may not
adequately perform. If the amount of liquid is greater than the
above-identified ranges, the wet-wipe may be oversaturated and
soggy and the liquid may pool in the bottom of the container.
[0067] Each wet-wipe is generally rectangular in shape and may have
any suitable unfolded width and length. For example, the wet-wipe
may have an unfolded length of from about 2.0 to about 80.0
centimeters and desirably from about 10.0 to about 25.0 centimeters
and an unfolded width of from about 2.0 to about 80.0 centimeters
and desirably from about 10.0 to about 25.0 centimeters.
Preferably, each individual wet-wipe is arranged in a folded
configuration and stacked one on top of the other to provide a
stack of wet-wipes or interfolded in a configuration suitable for
pop-up dispensing. Such folded configurations are well known to
those skilled in the art and include c-folded, z-folded,
quarter-folded configurations and the like. The stack of folded
wet-wipes may be placed in the interior of a container, such as a
plastic tub, to provide a package of wet-wipes for eventual sale to
the consumer. Alternatively, the wet-wipes may include a continuous
strip of material which has perforations between each wipe and
which may be arranged in a stack or wound into a roll for
dispensing.
[0068] The fibrous non-woven material or fibrous non-woven
composite material of the wet-wipes of the present invention may
include at least two plies of material having different physical
properties. The different physical properties which a ply may be
configured to provide by selecting the appropriate materials
include softness, resiliency, strength, flexibility, integrity,
toughness, absorbency, liquid retention, thickness, tear
resistance, surface texture, drapability, hand, wetability, wicking
ability and the like and combinations thereof. Preferably, the
fibrous non-woven materials and/or fibrous non-woven composite
materials used in a plied wet-wipe are configured to provide
softness and flexibility while maintaining adequate strength,
integrity and resiliency, particularly when wetted. For example,
the wet-wipes may include at least one ply of fibrous non-woven
material or fibrous non-woven composite material which is
configured to provide strength and resilience to the wet-wipe and
at least one other ply of a fibrous non-woven material or fibrous
non-woven composite material which is configured to provide a soft,
gentle wiping surface to the wet-wipe. Preferably, the wet-wipes
include a soft ply on each side of a strong and resilient ply such
that both exposed surfaces of the wipe provide a soft, gentle
surface for contact with the skin.
[0069] The fibrous non-woven material or fibrous non-woven
composite material may be formed by the microfibers and wood pulp
fibers without any adhesive, molecular or hydrogen bonds between
the two different types of fibers. The absorbent fibers are
preferably distributed uniformly throughout the matrix of
microfibers to provide a homogeneous material. The material is
formed by initially forming a primary air stream containing the
melt blown microfibers, forming a secondary air stream containing
the wood pulp fibers, merging the primary and secondary streams
under turbulent conditions to form an integrated air stream
containing a thorough mixture of the microfibers and wood pulp
fibers, and then directing the integrated air stream onto a forming
surface to air form the fabric-like material. The microfibers are
in a soft nascent condition at an elevated temperature when they
are turbulently mixed with the wood pulp fibers in air.
[0070] In one embodiment of the present invention, the ply(s) of
fibrous non-woven material or fibrous non-woven composite material
may have from about 20 to about 50 wt. % of the polymer fibers and
from about 80 to about 50 wt. % of the pulp fibers. A more specific
ratio of the polymer fibers to the pulp fibers may be from about 25
to about 40 wt. % of the polymer fibers and from about 75 to about
60 wt. % of the pulp fibers. A more specific ratio of the polymer
fibers to the pulp fibers may be from about 30 to about 40 wt. % of
the polymer fibers and from about 70 to about 60 wt. % of the pulp
fibers. The most specific ratio of the polymer fibers to the pulp
fibers may be about 35 wt. % of the polymer fibers and about 65 wt.
% of the pulp fibers.
[0071] Non-limiting examples of the polymers suitable for
practicing the invention are polyolefin materials such as, for
example, polyethylene, polypropylene and polybutylene, including
ethylene copolymers, propylene copolymers and butylene copolymers
thereof. A particularly useful polypropylene is Basell PF-105.
Additional polymers are disclosed in U.S. Pat. No. 5,385,775.
[0072] Pulp fibers of diverse natural origin are applicable in the
present invention. Digested cellulose fibers from softwood (derived
from coniferous trees), hardwood (derived from deciduous trees) or
cotton linters may be utilized. Pulp fibers from Esparto grass,
bagasse, kemp, flax, and other lignaceous and cellulose fiber
sources may also be utilized as raw material in the present
invention. For reasons of cost, ease of manufacture and
disposability, preferred fibers are those derived from wood pulp
(i.e., cellulose fibers). A commercial example of such a wood pulp
material is available from Weyerhaeuser as CF-405. Generally wood
pulp fibers may be utilized. Applicable wood pulps include chemical
pulps, such as Kraft (i.e., sulfate) and sulfite pulps, as well as
mechanical pulps including, for example, groundwood,
thermomechanical pulp (i.e., TMP) and chemithermomechanical pulp
(i.e., CTMP). Completely bleached, partially bleached and
unbleached fibers are useful herein. It may frequently be desired
to utilize bleached pulp for its superior brightness and consumer
appeal.
[0073] Also useful in the present invention are fibers derived from
recycled paper, which may contain any or all of the above
categories as well as other non-fibrous materials such as fillers
and adhesives used to facilitate the original paper making
process.
[0074] The ply(s) of fibrous non-woven material or fibrous
non-woven composite material may be non-woven materials such as,
for example, spunbonded webs, meltblown webs, air laid ply webs,
bonded carded webs, hydroentangled webs, wet-formed webs or any
combination thereof. In one embodiment of the present invention,
one or more plies of a multi-ply fibrous non-woven material and/or
fibrous non-woven composite material having, for example, at least
one ply of spunbonded web joined to at least one ply of meltblown
web, bonded carded web or other suitable material.
[0075] One or both of the plies of a multi-ply product may be a
composite material made of a mixture of two or more different
fibers or a mixture of fibers and particulates. Such mixtures may
be formed by adding fibers and/or particulates to the gas stream in
which meltblown fibers are carried so that an intimate entangled
commingling of meltblown fibers and other materials, e.g., wood
pulp, staple fibers and particulates such as, for example,
hydrocolloid (hydrogel) particulates commonly referred to as
superabsorbent materials, occurs prior to collection of the
meltblown fibers upon a collecting device to form a coherent web of
randomly dispersed meltblown fibers and other materials such as
disclosed in U.S. Pat. No. 4,100,324, to Anderson et al.
[0076] A suitable material for practicing the present invention is
a fibrous non-woven composite material commonly referred to as
"coform." Coform is an air-formed matrix material of thermoplastic
polymeric meltblown fibers such as, for example, microfibers having
an average fiber diameter of less than about 10 microns, and a
multiplicity of individualized absorbent pulp fibers such as, for
example, wood pulp fibers disposed throughout the matrix of polymer
microfibers and engaging at least some of the microfibers to space
the microfibers apart from each other. The absorbent pulp fibers
are interconnected by and held captive within the matrix of
microfibers by mechanical entanglement of the microfibers with the
absorbent pulp fibers, the mechanical entanglement and
interconnection of the microfibers and absorbent pulp fibers alone
forming a coherent integrated fibrous non-woven structure.
[0077] The coherent integrated fibrous structure may be formed by
the microfibers and absorbent pulp fibers without any adhesive,
molecular or hydrogen bonds between the two different types of
fibers. The absorbent pulp fibers are typcially distributed
uniformly throughout the matrix of microfibers to provide a
homogeneous material. The fibrous non-woven material is formed by
initially forming a primary air stream containing the melt blown
microfibers, forming a secondary air stream containing the wood
pulp fibers, merging the primary and secondary streams under
turbulent conditions to form an integrated air stream containing a
thorough mixture of the microfibers and wood pulp fibers, and then
directing the integrated air stream onto a forming surface to air
form the fabric-like material. The microfibers are in a soft
nascent condition at an elevated temperature when they are
turbulently mixed with the wood pulp fibers in air.
[0078] In one embodiment of the present invention, the plies of
fibrous non-woven material or fibrous non-woven composite material
are coform plies having from about 20 to about 50 wt. % of the
polymer fibers and from about 80 to about 50 wt. % of the pulp
fibers. A more specific ratio of the polymer fibers to the pulp
fibers may be from about 25 to about 40 wt. % of the polymer fibers
and from about 75 to about 60 wt. % of the pulp fibers. A more
specific ratio of the polymer fibers to the pulp fibers may be from
about 30 to about 40 wt. % of the polymer fibers and from about 70
to about 60 wt. % of the pulp fibers. The most specifically the
ratio of the polymer fibers to the pulp fibers is about 35 wt. % of
the polymer fibers and about 65 wt. % of the pulp fibers.
[0079] One of the plies of fibrous non-woven material may be made
of pulp fibers, including wood pulp fibers, to form a material such
as, for example, a tissue ply. Additionally, the plies of fibrous
non-woven material or fibrous non-woven composite material may be
plies of hydraulically entangled fibers such as, for example,
hydraulically entangled mixtures of wood pulp and staple fibers
such as disclosed in U.S. Pat. No. 4,781,966, to Taylor.
[0080] The plies of fibrous non-woven material or fibrous non-woven
composite material may be joined together or to other plies of
material in at least two places by any suitable means such as, for
example, thermal bonding or ultrasonic welding which softens at
least portions of at least one of the materials. The joining may be
produced by applying heat and/or pressure to the materials of the
plies by heating these portions to at least the softening
temperature of the material with the lowest softening temperature
to form a reasonably strong and permanent bond between the
re-solidified softened portions of the materials of the plies.
[0081] As may be appreciated, the bonding between the plies may be
a point bonding. Various bonding patterns may be used, depending
upon the desired tactile properties of the final composite laminate
of the plies. The bonding points are preferably evenly distributed
over the bonding area of the plies.
[0082] With regard to thermal bonding, one skilled in the art will
appreciate that the temperature to which the materials comprising
the plies, or at least the bond sites thereof, are heated for
heat-bonding will depend not only on the temperature of the heated
roller(s) or other heat sources but on the residence time of the
materials on the heated surfaces, the compositions of the materials
comprising the plies, the basis weights of the materials of the
plies and the specific heats and thermal conductivities of the
materials of the plies. Typically, the bonding may be conducted at
a temperature of from about 40.degree. to about 80.degree. C.
Specifically, the bonding may be conducted at a temperature of from
about 55.degree. to about 75.degree. C. More specifically, the
bonding may be conducted at a temperature of from about 60.degree.
to about 70.degree. C. The typical pressure range, on the rollers,
may be from about 18 to about 56.8 Kg per linear cm (KLC) The
specific pressure range, on the rollers, may be from about 18 to
about 24 Kg per linear cm (KLC). However, for a given combination
of materials of the plies, and in view of the herein contained
disclosure the processing conditions necessary to achieve
satisfactory bonding may be readily determined by one of skill in
the art.
[0083] The present invention will now be described in greater
detail with reference to the Figures. A variety of conventional
pulping apparatuses and operations can be used with respect to the
pulping phase, pulp processing, and drying of pulp fiber. It is
understood that the pulp fibers could be virgin pulp fiber or
recycled pulp fiber. Nevertheless, particular conventional
components are illustrated for purposes of providing the context in
which the various embodiments of the present invention can be used.
Improved retention of chemical additives by the pulp fibers may be
obtained by treating the pulp fibers according to the present
invention rather than treating the pulp fibers in wet end additions
at manufacturing machines. In addition, the present invention
allows for quick pulp fiber grade changes at the manufacturing
mills.
[0084] FIG. 1 depicts pulp processing preparation equipment used to
apply water insoluble chemical additives to pulp fibers according
to one embodiment of the present invention. A fiber slurry 10 is
prepared and thereafter transferred through suitable conduits (not
shown) to the headbox 28 where the fiber slurry 10 is injected or
deposited into a fourdrinier section 30 thereby forming a wet
fibrous web 32. The wet fibrous web 32 may be subjected to
mechanical pressure to remove process water. It is understood that
the process water may contain process chemicals used in treating
the fiber slurry 10 prior to a web formation step. In the
illustrated embodiment, the fourdrinier section 30 precedes a press
section 44, although alternative dewatering devices such as a nip
thickening device, or the like may be used in a pulp sheet machine.
The fiber slurry 10 is deposited onto a foraminous fabric 46 such
that the fourdrinier section filtrate 48 is removed from the wet
fibrous web 32. The fourdrinier section filtrate 48 comprises a
portion of the process water. The press section 44 or other
dewatering device known in the art suitably increases the fiber
consistency of the wet fibrous web 32 to about 30 percent or
greater, and particularly about 40 percent or greater thereby
creating a dewatered web 33. The process water removed as
fourdrinier section filtrate 48 during the web forming step may be
used as dilution water for dilution stages in the pulp processing
or discarded.
[0085] The dewatered fibrous web 33 may be further dewatered in
additional press sections or other dewatering devices known in the
art. The suitably dewatered fibrous web 33 may be transferred to a
dryer section 34 where evaporative drying is carried out on the
dewatered fibrous web 33 to an airdry consistency, thereby forming
a dried fibrous web 36. The dried fibrous web 36 is thereafter
wound on a reel 37 or slit, cut into sheets, and baled via a baler
(not shown) for delivery to manufacturing machines 38 (shown in
FIG. 3).
[0086] A water insoluble chemical additive 24 may be added or
applied to the dewatered fibrous web 33 or the dried fibrous web 36
at a variety of addition points 35a, 35b, 35c, and 35d as shown in
FIG. 1. It is understood that while only four addition points 35a,
35b, 35c, and 35d are shown in FIG. 1, the application of the water
insoluble chemical additive 24 may occur at any point between the
point of initial dewatering of the wet fibrous web 32 to the point
the dried fibrous web 36 is wound on the reel 37 or baled for
transport to the manufacturing machines 38. The addition point 35a
shows the addition of the water insoluble chemical additive 24
within press section 44. The addition point 35b shows the addition
of the water insoluble chemical additive 24 between the press
section 44 and the dryer section 34. The addition point 35c shows
the addition of the water insoluble chemical additive in the dryer
section 34. The addition point 35d shows the addition of the water
insoluble chemical additive 24 between the dryer section 34 and the
reel 37 or baler (not shown).
[0087] The amount of water insoluble chemical additive retained by
the chemically treated pulp fibers is about 0.1 kilogram per metric
ton or greater. In particularly desirable embodiments, the amount
of retained water insoluble chemical additive is about 0.5
kg/metric ton or greater, particularly about 1 kg/metric ton or
greater, and more particularly about 2 kg/metric ton or greater.
Once the chemically treated pulp fibers are exposed to a liquid,
the amount of unretained water insoluble chemical additive in the
process water phase or product solution is between 0 and about 50
percent, particularly between 0 and about 30 percent, and more
particularly between 0 and about 10 percent, of the amount of water
insoluble chemical additive retained by the chemically treated pulp
fibers.
[0088] Chemistries suitable for use in the present invention
include those not soluble in water. Particularly useful are those
water insoluble chemistries that provide a product enhancement
benefit when incorporated into a fibrous non-woven material and
products made therefrom. Even more useful are those water insoluble
chemistries that will not extract with water after having been
adsorbed onto cellulosic fiber surfaces. Chemical classifications
suitable for use in the invention include, but are not limited to,
mineral oil, petrolatum, olefins, alcohols, fatty alcohols,
ethoxylated fatty alcohols, esters, high molecular weight
carboxylic and polycarboxylic acids and their salts,
polydimethylsiloxane and modified polydimethylsiloxane. Modified
polydimethylsiloxanes can include amino-functional
polydimethylsiloxanes, alkylene oxide-modified
polydimethylsiloxane, organomodified polysiloxanes, mixtures of
cyclic and non-cyclic modified polydimethylsiloxanes and the like.
It should be recognized that water insoluble chemical additives can
be applied as dispersions or emulsions and still fall within the
scope of the present invention.
[0089] A list of water insoluble chemical additives that can be
used in conjunction with the present invention include: dry
strength agents, wet strength agents, softening agents, debonding
agents, adsorbency agents, sizing agents, dyes, optical
brighteners, chemical tracers, opacifiers, dryer adhesive
chemicals, and the like. Additional water insoluble chemical
additives may include: pigments, emollients, humectants, viricides,
bactericides, buffers, waxes, fluoropolymers, odor control
materials and deodorants, zeolites, perfumes, vegetable and mineral
oils, polysiloxane compounds, surfactants, moisturizers, UV
blockers, antibiotic agents, lotions, fungicides, preservatives,
aloe-vera extract, vitamin E, or the like.
[0090] Polysiloxanes encompass a very broad class of compounds.
They are characterized in having a backbone structure: 1
[0091] where R' and R" can be a broad range of organo and
non-organo groups including mixtures of such groups and where n is
an integer .gtoreq.2. These polysiloxanes may be linear, branched
or cyclic. They include a wide variety of polysiloxane copolymers
containing various compositions of functional groups, hence, R' and
R" actually may represent many different types of groups within the
same polymer molecule. The organo or non-organo groups may be
capable of reacting with cellulose to covalently, ionically or
hydrogen bond the polysiloxane to the cellulose. These functional
groups may also be capable of reacting with themselves to form
crosslinked matrixes with the cellulose. The scope of the invention
should not be construed as limited by a particular polysiloxane
structure so long as that polysiloxane structure delivers the
aforementioned product or process benefits.
[0092] While not wishing to be bound by theory, the softness
benefits that polysiloxanes deliver to cellulose containing
products is believed to be, in part, related to the molecular
weight of the polysiloxane. Viscosity is often used as an
indication of molecular weight of the polysiloxane as exact number
or weight average molecular weights are often difficult to
determine. The viscosity of the polysiloxanes of the present
invention is greater than about 25 centipoise, more typically
greater than 50 centipoise and most typcially greater than 100
centipoise. Viscosity as referred to herein refers to the viscosity
of the neat polysiloxane itself and not to the viscosity of an
emulsion if so delivered. It should also be understood that the
polysiloxanes of the current invention may be delivered as
solutions containing diluents. Such diluents may lower the
viscosity of the solution below the limitations set above, however,
the efficacious part of the polysiloxane should conform to the
viscosity ranges given above. Examples of such diluents include but
is not limited to oligomeric and cyclo-oligomeric polysiloxanes
such as octamethylcyclotetrasiloxane, octamethyltrisiloxane,
decamethylcyclopentasiloxane, decamethyltetrasiloxane and the like
including mixtures of said compounds.
[0093] A specific class of polysiloxanes suitable for the invention
has the general formula: 2
[0094] Wherein the R.sup.1-R.sup.8 moieties can be independently
any organofunctional group including C.sub.1 or higher alkyl
groups, ethers, polyethers, polyesters, amines, imines, amides, or
other functional groups including the alkyl and alkenyl analogues
of such groups and y is an integer >1. Preferably the
R.sup.1-R.sup.8 moieties are independently any C.sub.1or higher
alkyl group including mixtures of said alkyl groups. Exemplary
fluids are the DC-200 fluid series, manufactured and sold by Dow
Corning, Inc.
[0095] Another exemplary class of functionalized polysiloxanes
suitable for the present invention is the polyether polysiloxanes.
Such polysiloxanes are widely taught in the art and are usually
incorporated wholly or in part with other functional polysiloxanes
as a means of improving hydrophilicity of the silicone treated
product. Such polysiloxanes will generally have the following
structure: 3
[0096] Wherein, x and z are integers >0. y is an integer
.gtoreq.0. The mole ratio of x to (x+y+z) can be from about 0.05
percent to about 95 percent. The ratio of y to (x+y+z) can be from
about 0 percent to about 25%. The R.sup.0-R.sup.9 moieties can be
independently any organofunctional group including C.sub.1 or
higher alkyl groups, ethers, polyethers, polyesters, amines,
imines, amides, or other functional groups including the alkyl and
alkenyl analogues of such groups. The R.sup.10 moiety is an amino
functional moiety including but not limited to primary amine,
secondary amine, tertiary amines, quaternary amines, unsubstituted
amides and mixtures thereof. An exemplary R.sup.10 moiety contains
one amine group per constituent or two or more amine groups per
substituent, separated by a linear or branched alkyl chain of
C.sup.1 or greater. R.sup.11 is a polyether functional group having
the generic formula:
--R.sup.12--(R.sup.13--O).sub.a--(R.sup.14O).sub.b--R.sup.15,
wherein R.sup.12, R.sup.13, and R.sup.14 are independently
C.sub.1-4 alkyl groups, linear or branched; R.sup.15 can be H or a
C.sub.1-30 alkyl group; and, "a" and "b" are integers of from about
1 to about 100, more specifically from about 5 to about 30.
Exemplary fluids are the Wetsoft CTW family manufactured and sold
by Wacker, Inc. Other exemplary fluids can be found in U.S. Pat.
No. 6,432,270 issued to Liu, et. al. and incorporated by reference
herein.
[0097] Most typically, the polysiloxane is chosen from the group of
so called "amino functional" functional polysiloxanes of the
general formula: 4
[0098] Wherein, x and y are integers >0. The mole ratio of x to
(x+y) can be from about 0.005 percent to about 25 percent. The
R.sup.1-R.sup.9 moieties can be independently any organofunctional
group including C.sub.1 or higher alkyl groups, ethers, polyethers,
polyesters, amines, imines, amides, or other functional groups
including the alkyl and alkenyl analogues of such groups. The
R.sub.10 moiety is an amino functional moiety including but not
limited to primary amine, secondary amine, tertiary amines,
quaternary amines, unsubstituted amides and mixtures thereof. An
exemplary R.sup.10 moiety contains one amine group per constituent
or two or more amine groups per substituent, separated by a linear
or branched alkyl chain of C.sup.1 or greater. An exemplary
material includes but is not limited to 2-8220 fluid manufactured
and sold by Dow Corning.
[0099] It should also be recognized that often it is advantageous
to use a blend of various functional polysiloxanes. For example,
amino functional polysiloxanes may be blended with polyether
functional polysiloxanes and this blend applied to the product. The
polyether functional polysiloxane helps mitigate any undesirable
hydrophobicity within the product. It should be understood that
such blends fall within the scope of the present invention.
[0100] At the manufacturing machines 38, one example of such
machines 38 is shown in FIG. 3, a primary gas stream 66 containing
polymeric microfibers, formed by any known method, such as
meltblown techniques. The molten polymeric material is extruded
through a diehead 68 by converging flows of high velocity heated
gas (usually air) supplied from nozzles 70 and 72. The primary gas
stream 66 is merged with a secondary gas stream 74 containing
individualized chemically treated pulp fibers having the chemical
additive 24 so as to integrate the two different fibrous materials
into a single integrated stream 76 in a single step. The
manufacturing machine 38 typically includes a conventional picker
roll 78 having teeth for divellicating pulp sheets 80 into
individual chemically treated pulp fibers having the chemical
additive 24. The chemically treated pulp sheets 80 having the
chemical additive 24 are fed radially by means of rolls 82. The
individualized chemically treated pulp fibers having the chemical
additive 24 are conveyed downwardly toward the primary air stream
66 through a forming nozzle or duct 84. A housing 86 encloses the
picker roll 78 and provides a passage 88 between the housing 86 and
the surface of the picker roll 78. The secondary gas stream 74
supplied through duct 90 passes through the passage 88 while
carrying the individualized chemically treated pulp fibers having
the chemical additive 24 through the forming nozzle 84. To convert
the fibrous blend in the integrated stream 76 into an integral
fibrous non-woven material or fibrous non-woven composite material
92, the integrated stream 76 passes through a nip of a pair of
vacuum rolls 94 and 96 having foraminous surfaces that rotate
continuously over a pair of fixed vacuum nozzles 98 and 100. As the
integrated stream 76 is pulled into the vacuum nozzles 98 and 100,
the carrying gas is removed while the fibrous blend is supported
and slightly compressed by the opposed surfaces of the two rolls 94
and 96. The integral fibrous non-woven material or fibrous
non-woven composite material 92 removed from the vacuum roll nip
and conveyed to a wind-up roll 102. The integral fibrous non-woven
material or fibrous non-woven composite material 92 is passed
through an ultrasonic embossing station 108 comprising an
ultrasonic calendaring head 104 and a patterned anvil roll 106. The
finished product, such as a wet-wipe has enhanced qualities due to
the retention of the chemical additive 24 by the chemically treated
pulp fibers during the pulp processing. In other embodiments of the
present invention, additional chemical additive 24 may be added to
the chemically treated pulp fiber stock preparation at the
manufacturing machine 38.
[0101] FIG. 2 depicts an alternative embodiment of the present
invention in which sequential addition of the first and second
water insoluble chemical additives 24 and 25, respectively, are
added to the dewatered fibrous web slurry 33 and/or the dried
fibrous web 36. It is understood that the addition of the first
water insoluble chemical additive 24 may occur any where that the
second water insoluble chemical additive 25 may be applied. It is
also understood that the addition of the second water insoluble
chemical additive 25 may occur any where that the first water
insoluble chemical additive 24 may be applied. A fiber slurry 10 is
prepared and thereafter transferred through suitable conduits (not
shown) to the headbox 28 where the fiber slurry 10 is injected or
deposited into a fourdrinier section 30 thereby forming a wet
fibrous web 32. The wet fibrous web 32 may be subjected to
mechanical pressure to remove process water. In the illustrated
embodiment, the fourdrinier section 30 precedes a press section 44,
although alternative dewatering devices such as a nip thickening
device, or the like known in the art may be used in the pulp sheet
machine. The fiber slurry 10 is deposited onto a foraminous fabric
46 such that the fourdrinier section filtrate 48 is removed from
the wet fibrous web 32. The fourdrinier section filtrate 48
comprises a portion of the process water. The press section 44 or
other dewatering device suitably increases the fiber consistency of
the wet fibrous web 32 to about 30 percent or greater, and
particularly about 40 percent or greater thereby forming a
dewatered fibrous web 33. The process water removed as fourdrinier
section filtrate 48 during the web forming step may be used as
dilution water for dilution stages in the pulp processing or
discarded.
[0102] The dewatered fibrous web 33 may be further dewatered in
additional press sections 44 or other dewatering devices known in
the art. The suitably dewatered fibrous web 33 may be transferred
to a dryer section 34 where evaporative drying is carried out on
the dewatered fibrous web 33 to an airdry consistency, thereby
forming a dried fibrous web 36. The dried fibrous web 36 is
thereafter wound on a reel 37 or slit, cut into sheets, and baled
via a baler (not shown) for delivery to manufacturing machines 38
(shown in FIG. 3).
[0103] The first water insoluble chemical additive 24 may be added
or applied to the dewatered fibrous web 33 or the dried fibrous web
36 at a variety of addition points 35a, 35b, 35c, and 35d as shown
in FIG. 2. It is understood that while only four addition points
35a, 35b, 35c, and 35d are shown in FIG. 2, the application of the
first water insoluble chemical additive 24 may occur at any point
between the point of initial dewatering of the wet fibrous web 32
to the point the dried fibrous web 36 is wound on the reel 37 or
baled for transport to the manufacturing machines 38. The addition
point 35a shows the addition of the first water insoluble chemical
additive 24 within press section 44. The addition point 35b shows
the addition of the first chemical additive 24 between the press
section 44 and the dryer section 34. The addition point 35c shows
the addition of the first water insoluble chemical additive 24
within the dryer section 34. The addition point 35d shows the
addition of the first water insoluble chemical additive 24 between
the dryer section 34 and the reel 37 or baler.
[0104] The second water insoluble chemical additive 25 may be added
or applied to the dewatered fibrous web 33 or the dried fibrous web
36 at a variety of addition points 35a, 35b, 35c, and 35d as shown
in FIG. 2. It is understood that while only four addition points
35a, 35b, 35c, and 35d are shown in FIG. 2, the application of the
second water insoluble chemical additive 25 may occur at any point
between the point of initial dewatering of the wet fibrous web 32
to the point the dried fibrous web 36 is wound on the reel 37 or
baled for transport to the manufacturing machines 38 downstream of
at least the initial point of application of the first water
insoluble chemical additive 24. The addition point 35a shows the
addition of the second water insoluble chemical additive 25 within
press section 44. The addition point 35b shows the addition of the
second water insoluble chemical additive 25 between the press
section 44 and the dryer section 34. The addition point 35c shows
the addition of the second chemical additive within the dryer
section 34. The addition point 35d shows the addition of the second
water insoluble chemical additive 25 between the dryer section 34
and the reel 37 or baler.
[0105] At the manufacturing machines 38, one example of such
machines 38 is shown in FIG. 3, a primary gas stream 66 containing
polymeric microfibers, formed by any known method, such as
meltblown techniques. The molten polymeric material is extruded
through a diehead 68 by converging flows of high velocity heated
gas (usually air) supplied from nozzles 70 and 72. The primary gas
stream 66 is merged with a secondary gas stream 74 containing
individualized chemically treated pulp fibers having the chemical
additives 24 and 25 so as to integrate the two different fibrous
materials into a single integrated stream 76 in a single step. The
manufacturing machine 38 typically includes a conventional picker
roll 78 having teeth for divellicating pulp sheets 80 into
individual chemically treated pulp fibers having the chemical
additives 24 and 25. The chemically treated pulp sheets 80 having
the chemical additives 24 and 25 are fed radially by means of rolls
82. The individualized chemically treated pulp fibers having the
chemical additives 24 and 25 are conveyed downwardly toward the
primary air stream 66 through a forming nozzle or duct 84. A
housing 86 encloses the picker roll 78 and provides a passage 88
between the housing 86 and the surface of the picker roll 78. The
secondary gas stream 74 supplied through duct 90 passes through the
passage 88 while carrying the individualized chemically treated
pulp fibers having the chemical additives 24 and 25 through the
forming nozzle 84. To convert the fibrous blend in the integrated
stream 76 into an integral fibrous non-woven material or fibrous
non-woven composite material 92, the integrated stream 76 passes
through a nip of a pair of vacuum rolls 94 and 96 having foraminous
surfaces that rotate continuously over a pair of fixed vacuum
nozzles 98 and 100. As the integrated stream 76 is pulled into the
vacuum nozzles 98 and 100, the carrying gas is removed while the
fibrous blend is supported and slightly compressed by the opposed
surfaces of the two rolls 94 and 96. The integral fibrous non-woven
material or fibrous non-woven composite material 92 removed from
the vacuum roll nip and conveyed to a wind-up roll 102. The
integral fibrous non-woven material or fibrous non-woven composite
material 92 is passed through an ultrasonic embossing station 108
comprising an ultrasonic calendaring head 104 and a patterned anvil
roll 106. The finished product, such as a wet-wipe has enhanced
qualities due to the retention of the chemical additives 24 and 25
by the chemically treated pulp fibers during the pulp processing.
In other embodiments of the present invention, additional chemical
additives 24 and 25 may be added to the chemically treated pulp
fiber stock preparation at the manufacturing machine 38.
[0106] In other embodiments, it is understood that a third, fourth,
fifth, so forth, water insoluble chemical additives may be used to
treat the dewatered fibrous web 33 and/or dried fibrous web 36.
[0107] The amount of first water insoluble chemical additive 24 is
suitably about 0.1 kg./metric ton of pulp fiber or greater. In
particular embodiments, the first water insoluble chemical additive
24 is a polysiloxane and is added in an amount from about 0.1
kg./metric ton of pulp fiber or greater.
[0108] The amount of the second water insoluble chemical additive
25 is suitably about 0.1 kg./metric ton of pulp fiber or greater.
In particular embodiments, the second water insoluble chemical
additive 25 is a polysiloxane and is added in an amount from about
0.1 kg./metric ton of pulp fiber or greater.
[0109] In other embodiments of the present invention, each of the
first and second water insoluble chemical additives 24 and 25 may
be added to the fiber slurry 10 at a variety of positions in the
pulp processing apparatus.
[0110] In other embodiments of the present invention, one batch of
pulp fibers may be treated with a first water insoluble chemical
additive 24 according to the method of the present invention as
discussed above while a second batch of pulp fibers may be treated
with a second water insoluble chemical additive 25 according to the
present invention. During the manufacturing process, different pulp
fibers or pulp fibers having different treatments may be processed
into a layered or plied fibrous non-woven material or a layered or
plied product made therefrom.
[0111] In other embodiments of the present invention, a gradient of
the first and/or the second water insoluble chemical additives 24
and 25 along the z-direction of the dewatered fibrous web 33 and/or
the dried fibrous web 36 may be established by a directed
application of the first and/or the second water insoluble chemical
additives 24 and 25. In one embodiment, the first and/or the second
water insoluble chemical additives 24 and 25 are applied to one
side of the dewatered fibrous web 33 and/or the dried fibrous web
36. In another embodiment, one side of the dewatered fibrous web 33
and/or the dried fibrous web 36 is saturated with the first and/or
the second water insoluble chemical additives 24 and 25. In another
embodiment, a dual gradient may be established in the z-direction
of the dewatered fibrous web 33 and/or the dried fibrous web 36 by
applying the first water insoluble chemical additive 24 to one side
of the dewatered fibrous web 33 and/or the dried fibrous web 36 and
applying the second water insoluble chemical additive 25 to the
other (opposing) side of the dewatered fibrous web 33 and/or the
dried fibrous web 36. The term "z-direction" refers to the
direction through the thickness of the web material.
[0112] The first and/or the second water insoluble chemical
additives 24 and 25 may be applied so as to establish a gradient
wherein about 100 percent of each of the first and/or the second
water insoluble chemical additives 24 and 25 is located from the
side of the dewatered fibrous web 33 and/or the dried fibrous web
36 treated with the first and/or the second water insoluble
chemical additives 24 and 25 to the middle of the dewatered fibrous
web 33 and/or the dried fibrous web 36 along the z-direction of the
dewatered fibrous web 33 and/or the dried fibrous web 36 and
substantially none of each of the first and/or the second water
insoluble chemical additives 24 and 25 is located from the middle
of the dewatered fibrous web 33 and/or the dried fibrous web 36 to
the opposing side of the dewatered fibrous web 33 and/or the dried
fibrous web 36 along the z-direction of the dewatered fibrous web
33 and/or the dried fibrous web 36.
[0113] The first and/or the second water insoluble chemical
additives 24 and 25 may be applied so as to establish a gradient
wherein about 66 percent of each of the first and/or the second
water insoluble chemical additives 24 and 25 is located from the
side of the dewatered fibrous web 33 and/or the dried fibrous web
36 treated with the first and/or the second water insoluble
chemical additives 24 and 25 to the middle of the dewatered fibrous
web 33 and/or the dried fibrous web 36 along the z-direction of the
dewatered fibrous web 33 and/or the dried fibrous web 36 and about
33 percent of each of the first and/or the second water insoluble
chemical additives 24 and 25 is located from the middle of the
dewatered fibrous web 33 and/or the dried fibrous web 36 to the
opposing side of the dewatered fibrous web 33 and/or the dried
fibrous web 36 along the z-direction of the dewatered fibrous web
33 and/or the dried fibrous web 36. The gradient may also be
established wherein about 100 percent, about 75 percent, about 60
percent, about 50 percent, about 40 percent, about 25 percent, or
about 0 percent of each of the first and/or second water insoluble
chemical additives 24 and 25 is located from one side of the
dewatered fibrous web 33 and/or the dried fibrous web 36 and about
0 percent, about 25 percent, about 40 percent, about 50 percent,
about 60 percent, about 75 percent, or about 100 percent of each of
the first and/or second water insoluble chemical additives 24 and
25 is located from the opposing side of the dewatered fibrous web
33 and/or the dried fibrous web 36.
[0114] It is understood that in any of these embodiments, the first
and second water insoluble chemical additives 24 and 25 may be each
applied on opposing sides of the dewatered fibrous web 33 and/or
the dried fibrous web 36. Alternatively, the first and second water
insoluble chemical additives 24 and 25 could be applied to both
opposing sides of the dewatered fibrous web 33 and/or the dried
fibrous web 36. In still another variation, the first and second
water insoluble chemical additives 24 and 25 could be applied to
only one side of the dewatered fibrous web 33 and/or the dried
fibrous web 36. Where only a first water insoluble chemical
additive 24 is applied to the dewatered fibrous web 33 and/or the
dried fibrous web 36, the first water insoluble chemical additive
24 may be applied to one side or both opposing sides of the
dewatered fibrous web 33 and/or the dried fibrous web 36
[0115] In another embodiment of the present invention, the amounts
of the first and/or second water insoluble chemical additives 24
and 25 may be reduced from typical amounts while still imparting
unique product characteristics due to the distribution of the first
and/or second water insoluble chemical additives 24 and 25 on or
within the dewatered fibrous web 33 and/or the dried fibrous web 36
as opposed to an embodiment of the present invention wherein an
equilibrated distribution of the first and/or second water
insoluble chemical additives 24 and 25 of the dewatered fibrous web
33 and/or the dried fibrous web 36. The establishment of a gradient
of the application of the first and/or the second water insoluble
chemical additives 24 and 25 of the dewatered fibrous web 33 and/or
the dried fibrous web 36 is one way in which this may be
accomplished.
[0116] A directed application of a water insoluble chemical
additive to treat only a portion of the pulp fibers according to
the present invention may result in a product produced having
different characteristics than a product having uniformly
chemically treated fibers. Additionally, directed applications
typically require a lower amount of the water insoluble chemical
additive to achieve paper enhancement, thereby minimizing the
detrimental effects that result from unretained water insoluble
chemical additives in the manufacturing water systems or in the
solutions that may be used with finished products.
[0117] A wide variety of fluidized bed coating systems can be
adapted to coat or treat pulp fibers with a water insoluble
chemical additive that enhances the properties of the pulp fibers
or the properties of the pulp fibers during the process or methods
of making chemically treated fibrous non-woven materials or
finished products made therefrom. For example, one can use a
Wurster Fluid Bed Coater such as the Ascoat Unit Model 101 of Lasko
Co. (Leominster, Mass.), the Magnacoater.RTM.) by Fluid Air, Inc.
(Aurora, Ill.), or the modified Wurster coater described in U.S.
Pat. No. 5,625,015 issued Apr. 29, 1997 to Brinen et al., herein
incorporated by reference. The Wurster fluidized bed coating
technology, one of the most popular methods for particle coating,
was originally developed for the encapsulation of solid particulate
materials such as powders, granules, and crystals, but according to
the present invention, can be adapted to deliver a coating of at
least one water insoluble chemical additive to the pulp fibers.
[0118] The coater is typically configured as a cylindrical or
tapered vessel (larger diameter at the top than at the bottom) with
air injection at the bottom through air jets or a distributor plate
having multiple injection holes. The pulp fibers are fluidized in
the gaseous flow. One or more spray nozzles inject the water
insoluble chemical additive initially provided as a liquid, slurry,
or foam at a point where good contact with the moving pulp fibers
can be achieved. The pulp fibers move upwards and descend behind a
wall or barrier, from whence the pulp fibers can be guided to again
enter the fluidized bed and be coated (treated) again, treated with
a second water insoluble chemical additive, or can be removed and
further processed. The pulp fibers may also be treated
simultaneously with two or more water insoluble chemical additives
using one or more nozzles. Ambient dry air or elevated air
temperature or the application of other forms of energy
(microwaves, infrared radiation, electron beams, ultraviolet
radiation, steam, and the like) causes drying or curing of the
chemical additive on the pulp fibers. The retention time of the
pulp fibers in the fluidized bed a plurality of times to provides
the desired amount of treatment of one or more water insoluble
chemical additives on the pulp fibers.
[0119] The original Wurster fluid bed coaters are described in U.S.
Pat. No. 2,799,241 issued Jul. 16, 1957 to D. E. Wurster; U.S. Pat.
No. 3,089,824 issued May 14, 1963 to D. E. Wurster; U.S. Pat. No.
3,117,024 issued Jan. 7, 1964 to J. A. Lindlof et al.; U.S. Pat.
No. 3,196,827 issued Jul. 27, 1965 to D. E. Wurster and J. A.
Lindlof; U.S. Pat. No. 3,207,824 issued Sep. 21, 1965 to D. E.
Wurster et al.; U.S. Pat. No. 3,241,520 issued Mar. 21, 1966 to D.
E. Wurster and J. A. Lindlof; and, U.S. Pat. No. 3,253,944 issued
May 31, 1966 to D. E. Wurster; all of which are herein incorporated
by reference. More recent examples of the use of Wurster coaters
are given in U.S. Pat. No. 4,623,588 issued Nov. 18, 1986 to
Nuwayser et al., herein incorporated by reference. A related device
is the coater is disclosed in U.S. Pat. No. 5,254,168 issued Oct.
19, 1993 to Littman et al., herein incorporated by reference.
[0120] Other coating methods need not rely on particle fluidization
of the pulp fibers in a gas stream. The pulp fibers may be sprayed
or treated with one or more water insoluble chemical additives
while being mechanically agitated by a shaker or other pulsating
device during the manufacturing process, such as while the pulp
fibers are dropped from one container to another, while the pulp
fibers are tumbled in a moving vessel or a vessel with rotating
paddles such as a Forberg particle coater (Forberg AS, Larvik,
Norway) which can be operated without applied vacuum to keep the
water insoluble chemical additives on the surface of the pulp
fibers, or while the pulp fibers rest in a bed, after which the
pulp fibers may be separated or broken up. In one embodiment, pulp
fibers and a water insoluble chemical additive may be first
combined and then the pulp fibers are separated into individually
coated (treated) pulp fibers by centrifugal forces, as disclosed in
U.S. Pat. No. 4,675,140 issued Jun. 23, 1987 to Sparks et al.,
herein incorporated by reference.
[0121] Systems for coating dry particles can also be adapted for
pulp fibers according to the present invention. Examples of such
equipment include:
[0122] Magnetically Assisted Impaction Coating (MAIC) by Aveka
Corp. (Woodbury, Minn.), wherein magnetic particles in a chamber
are agitated by varying magnetic fields, causing target particles
and coating materials to repeatedly collide, resulting in the
coating of the target particles;
[0123] Mechanofusion by Hosokawa Micron Corp. (Hirakata, Osaka,
Japan), wherein particles and coating materials in a rotating drum
are periodically forced into a gap beneath an arm pad, causing the
materials to become heated and joined together to form coated
particles, a process that is particularly effective when a
thermoplastic material is involved;
[0124] the Theta Composer of Tokuju Corporation (Hiratsuka, Japan),
wherein particles and coating material are mechanically brought
together by a pair of rotating elliptical heads;
[0125] Henschel mixers from Thyssen Henschel Industritechnik
(Kassel, Germany), believed to be useful for combining particles
with polymeric materials;
[0126] the Hybridizer of Nara Machinery (Tokyo, Japan), which
employs blades rotating at high speed to impact a coating powder
onto particles carried by an air stream; and,
[0127] the Rotary Fluidized Bed Coater of the New Jersey Institute
of Technology, which comprises a porous rotating cylinder with
particles inside. Pressurized air enters the walls of the cylinder
and flows toward a central, internal exit port. Air flow through
the walls of the chamber can fluidize the particles, acting against
centrifugal force. As the particles are fluidized, a coating
material injected into the chamber can impinge upon the particles
and coat them.
[0128] With dry particle coating systems, the pulp fibers may first
be treated with a first water insoluble chemical additive by any
technique, and then subsequently treated with a second water
insoluble chemical additive in powder form. The pulp fibers may
also be treated with the first and second water insoluble chemical
additives simultaneously. Doing so creates a coating treatment in
which the second water insoluble chemical additive is selectively
distributed near the exterior surface of the coating treatment, and
in which the portion of the coating treatment next to the pulp
fibers may be substantially free of the second water insoluble
chemical additive.
[0129] By way of example, FIGS. 4 and 5 illustrate two versions of
a fluidized bed coating process that can be used to coat pulp
fibers 130 according to the present invention. In FIG. 4, the
depicted apparatus 120 comprises an inner cylindrical partition
122, an outer cylindrical partition 124, and a distributor plate
126 having a central porous or sintered region for injection of gas
to entrain pulp fibers 130. The majority of the fluidizing gas flow
is directed through the inner cylindrical partition 122. Thus, the
general flow pattern of the pulp fibers 130 is upward inside the
inner cylindrical partition 122, and downward outside the inner
cylindrical partition 122. Unlike several common versions of the
Wurster process, in the apparatus 120 of FIG. 4, the spray nozzle
128 is located at the bottom of the apparatus 120, just above the
distributor plate 126. The nozzle 128 sprays upward, providing a
cocurrent application of a spray 132 of a water insoluble chemical
additive to the pulp fibers 130. Any suitable spray nozzle and
delivery system known in the art can be used.
[0130] FIG. 5 is similar to FIG. 4 except that the inner
cylindrical partition 122 of FIG. 4 has been removed, and the
porous or sintered region of the distributor plate 126 now
substantially extends over the entire distributor plate 126.
[0131] Many aspects of the apparatus in FIG. 4 can be modified
within the scope of the present invention. For example, the inner
cylindrical partition 122 may be replaced with one or more baffles
or flow guides (not shown). The walls of either the outer
cylindrical partition 124 or inner cylindrical partition 122 may be
tapered and may be interrupted with ports or openings for removal
of the pulp fibers 130 or addition of a water insoluble chemical
additive from one or more spray nozzles (not shown). Either the
outer cylindrical partition 124 or the inner cylindrical partition
122 or both may rotate, vibrate, or oscillate. The distributor
plate 126 may also move during the treatment operation (e.g.,
vibrate, rotate, or oscillate). A variety of spray nozzles and
delivery systems can be applied to deliver the coating material,
including the Silicone Dispensing System of GS Manufacturing (Costa
Mesa, Calif.). The water insoluble chemical additives can be
applied by spraying from any position in the apparatus 120, or by
curtain coating or slot coating or other processes applied to a
moving stream of pulp fibers 130.
[0132] While the invention has been described in conjunction with
specific embodiments, it is to be understood that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the foregoing description.
Accordingly, this invention is intended to embrace all such
alternatives, modifications and variations, which fall within the
spirit and scope of the appended claims.
* * * * *