U.S. patent application number 11/464633 was filed with the patent office on 2008-02-21 for controlled flow polymer blends and products including the same.
Invention is credited to Gerald Timothy Keep.
Application Number | 20080045102 11/464633 |
Document ID | / |
Family ID | 38658712 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080045102 |
Kind Code |
A1 |
Keep; Gerald Timothy |
February 21, 2008 |
CONTROLLED FLOW POLYMER BLENDS AND PRODUCTS INCLUDING THE SAME
Abstract
The present invention is directed to polymer blends having
controlled flow properties. The polymer blends can be useful in
various applications including bonding systems and additive
delivery systems, which can provide durable binding and/or delivery
and/or affixing of additives. The polymer blends can include at
least two different components, at least one being a polymer
component having a higher molecular than the other of the
components. When heated to an activating temperature, the resultant
blend exhibits desirable flow or wet out properties without applied
pressure. Despite the controlled flow properties, the blends do not
exhibit blocking or fusing properties typically associated with
high flow polymer materials.
Inventors: |
Keep; Gerald Timothy;
(Kingsport, TN) |
Correspondence
Address: |
SUMMA, ALLAN & ADDITON, P.A.
11610 NORTH COMMUNITY HOUSE ROAD, SUITE 200
CHARLOTTE
NC
28277
US
|
Family ID: |
38658712 |
Appl. No.: |
11/464633 |
Filed: |
August 15, 2006 |
Current U.S.
Class: |
442/59 ; 156/60;
442/327; 442/361; 442/381; 525/50 |
Current CPC
Class: |
C08F 255/00 20130101;
C09D 7/70 20180101; D01F 6/46 20130101; D06M 23/08 20130101; D01F
8/06 20130101; D06M 15/227 20130101; Y10T 442/20 20150401; D06M
2101/28 20130101; C08K 3/016 20180101; C08K 9/10 20130101; D04H
3/00 20130101; D04H 1/42 20130101; D06M 2101/06 20130101; Y10T
156/10 20150115; C09D 7/65 20180101; C08L 51/06 20130101; Y10T
442/60 20150401; Y10T 442/637 20150401; Y10T 442/659 20150401; C08L
51/06 20130101; C08L 2666/02 20130101; C08L 51/06 20130101; C08L
2666/04 20130101 |
Class at
Publication: |
442/59 ; 442/327;
442/361; 442/381; 156/60; 525/50 |
International
Class: |
D04H 13/00 20060101
D04H013/00 |
Claims
1. A polymer blend capable of substantially wetting out a surface
at a flow activating temperature without requiring the application
of substantial pressure, said polymer blend further having blocking
resistance properties, said polymer blend comprising: at least
about 10 percent by weight, based on the total weight of the
polymer blend, of a first blend component comprising at least one
polymer having a first molecular weight; and at least about 10
percent by weight, based on the total weight of the polymer blend,
of a second blend component comprising at least one compound having
a second molecular weight that is less than the first molecular
weight of the at least one polymer of the first blend component,
wherein the first molecular weight of the at least one polymer of
said first blend component is sufficiently high to prevent the
substantial wet out without the application of substantial pressure
of the at least one polymer of the first blend component at said
activating temperature, and wherein the second molecular weight of
the at least one compound of said second blend component is
sufficiently low so that the at least one compound of the second
blend component exhibits sufficiently high molecular mobility to
substantially prevent processing of the at least one compound of
the second blend component alone.
2. The polymer blend of claim 1, wherein said blend comprises at
least about 20 percent by weight of the first blend component.
3. The polymer blend of claim 2, wherein said blend comprises at
least about 30 percent by weight of the first blend component.
4. The polymer blend of claim 1, wherein said blend comprises at
least about 20 percent by weight of the second blend component.
5. The polymer blend of claim 4, wherein said blend comprises at
least about 30 percent by weight of the second blend component.
6. The polymer blend of claim 1, wherein the polymer blend
substantially wets out a surface without requiring the application
of substantial pressure in about one hour or less at said
activating temperature.
7. The polymer blend of claim 6, wherein the polymer blend
substantially wets out a surface without requiring the application
of substantial pressure in about two minutes or less at said
activating temperature.
8. The polymer blend of claim 6, wherein said activating
temperature comprises a temperature of about 150.degree. C. or
less.
9. The polymer blend of claim 8, wherein said activating
temperature is comprises a temperature ranging from about
100.degree. C. to about 150.degree. C.
10. The polymer blend of claim 8, wherein said activating
temperature is comprises a temperature of about 100.degree. C.
11. The polymer blend of claim 8, wherein said activating
temperature is comprises a temperature of about 125.degree. C.
12. The polymer blend of claim 6, wherein said activating
temperature is comprises a temperature of about 150.degree. C. or
higher.
13. The polymer blend of claim 1, wherein the first blend component
comprises at least one polymer having a molecular weight at least
about three times higher than the molecular weight of the at least
one compound of the second blend component.
14. The polymer blend of claim 13, wherein the first blend
component comprises at least one polymer having a molecular weight
at least about five times higher than the molecular weight of the
at least one compound of the second blend component.
15. The polymer blend of claim 1, wherein the second component
comprises at least one compound having a number average molecular
weight of about 6000 or less.
16. The polymer blend of claim 1, wherein the first blend component
comprises at least one polymer having a first melt flow rate and
the second blend component comprises at least one compound having a
second melt flow rate that is greater than the melt flow rate of
the at least one polymer of the first blend component.
17. The polymer blend of claim 16, wherein the second blend
component comprises at least one compound having a melt flow rate
of at least about five times greater than the melt flow rate of the
at least one polymer of the first blend component.
18. The polymer blend of claim 17, wherein the second blend
component comprises at least one compound having a melt flow rate
of at least about ten times greater than the melt flow rate of the
at least one polymer of the first blend component.
19. The polymer blend of claim 18, wherein the first blend
component comprises at least one polymer having a melt flow rate of
about 1 or less and the second blend component comprises at least
one compound having a melt flow rate of about 100 or more.
20. The polymer blend of claim 1, wherein said polymer blend
comprises at least one polymer selected from the group consisting
of polyolefins, polyesters, acrylics, polyamides, elastomeric
polymers, polyacrylonitrile, acetals, fluoropolymers, epoxies,
phenoxies, vinyl alcohol polymers, polyesterimides, polyhydroxyl
alkanoates (PHA), polysulfone, polyetheretherketone, cellulose
acetate, rayons, biopolymers, polyurethanes, hot melt adhesives,
and copolymers, terpolymers and ionomers thereof, and combinations
thereof.
21. The polymer blend of claim 20, wherein said polymer blend
comprises at least one elastomeric polymer.
22. The polymer blend of claim 1, wherein the second blend
component comprises a substantially crystalline or semicrystalline
polymer.
23. The polymer blend of claim 22, wherein the first blend
component comprises at least one polymer having a glass transition
temperature (T.sub.g) and wherein the substantially crystalline or
semicrystalline polymer has a melting point that is greater than
the T.sub.g of the at least one polymer of the first blend
component.
24. The polymer blend of claim 20, wherein at least one of the
first and second blend components comprises a functionalized
polymer.
25. The polymer blend of claim 1, wherein at least one of the first
and second blend components comprises a polyolefin.
26. The polymer blend of claim 25, wherein both of the first and
the second blend components comprise a polyolefin.
27. The polymer blend of claim 25, wherein the polyolefin is
selected from the group consisting of polypropylene, polyethylene,
polybutylene, and copolymers, terpolymers, and combinations
thereof.
28. The polymer blend of claim 25, wherein the polyolefin is
functionalized.
29. The polymer blend of claim 25, wherein the polyolefin is
elastomeric.
30. The polymer blend of claim 28, wherein the polyolefin is
functionalized by reaction with at least one unsaturated anhydride,
unsaturated acid or unsaturated ester.
31. The polymer blend of claim 30, wherein the polyolefin is
modified by reaction with at least one unsaturated anhydride,
unsaturated acid or unsaturated ester selected from the group
consisting of maleic anhydride, citraconic anhydride, itaconic
anhydride, glutaconic anhydride, 2,3-dimethylmaleic anhydride,
maleic acid, fumaric acid, citraconic acid, itaconic acid,
mesaconic acid, glutaconic acid, acrylic acid, methacrylic acid,
crotonic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid,
dimethyl malcate, diethyl maleatc, di-n-propyl malcate, diisopropyl
maleate, dimethyl fumarate, diethyl fumarate, di-n-propyl fumarate,
di-isopropyl maleate, dimethyl itaconate, methyl acrylate, ethyl
acrylate, methyl methacrylate, ethyl methacrylate, methyl
crotonate, and ethyl crotonate.
32. The polymer blend of claim 31, wherein the polyolefin comprises
a maleic anhydride modified polyolefin.
33. The polymer blend of claim 27, wherein said polymer is
functionalized by oxidation.
34. The polymer blend of claim 1, further comprising at least one
additive.
35. The polymer blend of claim 34, wherein said at least one
additive comprises an additive selected from the group consisting
of antimicrobials, biocides, flame retardants, toxic absorbers,
conductive agents, abrasives, antioxidants, UV stabilizers,
optically active compounds, tracers, plating catalysts, fungicides,
mildewcides, phosphorescents, reflectants, smart fabric components,
polytetrafluoroethylene (PTFE), repellants, particulates,
reinforcing agents, fillers, pigments, talc, glass fibers, clays,
silicas, mineral silicates, mica, odor absorbers, nano-particles,
chemical deactivators, antistats, markers, counterfeit tracers,
fluorescents, ointments, and combinations thereof.
36. The polymer blend of claim 26, wherein at least one of said
first or second components comprises a maleic anhydride modified
polyolefin, said second component comprises a substantially
crystalline polyolefin, and said blend has a melting point within
20.degree. C. of the flow activation temperature of the blend.
37. A polymer blend capable of substantially wetting out a surface
at a flow activating temperature without requiring the application
of substantial pressure, said polymer blend further having blocking
resistance properties, said polymer blend comprising at least one
polymer having a first molecular weight and a glass transition
temperature T.sub.g, and a substantially crystalline compound
having a second molecular weight that is less than the first
molecular weight of the at least one polymer and having a melting
point that is greater than the T.sub.g of the at least one
polymer.
38. The polymer blend of claim 37, wherein said blend comprises a
functionalized polyolefin.
39. The polymer blend of claim 38, wherein the functionalized
polyolefin comprises a maleic anhydride modified polyolefin.
40. The polymer blend of claim 37, wherein said blend comprises an
elastomeric polyolefin.
41. A polymer blend capable of substantially wetting out a surface
at a flow activating temperature without requiring the application
of substantial pressure, said polymer blend further having blocking
resistance properties, said polymer blend comprising a phenoxy
having a first molecular weight and a glass transition temperature
T.sub.g; and a substantially crystalline plasticizer having a
second molecular weight that is less than the first molecular
weight of the phenoxy and having a melting point that is greater
than the T.sub.g of the phenoxy.
42. An article comprising the polymer blend of claim 41, wherein
said article is selected from the group consisting of fibers,
nonwoven fabrics, permeable films, impermeable films, foams, and
coatings.
43. A polymeric bonding system, comprising: an article comprising a
polymer blend capable of substantially wetting out a surface at a
flow activating temperature without requiring the application of
substantial pressure, said polymer blend further having blocking
resistance properties, said polymer blend comprising at least about
10 percent by weight, based on the total weight of the polymer
blend, of a first blend component comprising at least one polymer
having a first molecular weight and at least about 10 percent by
weight, based on the total weight of the polymer blend, of a second
blend component comprising at least one compound having a second
molecular weight that is less than the first molecular weight of
the at least one polymer of the first blend component, wherein the
first molecular weight of the at least one polymer of said first
blend component is sufficiently high to prevent the substantial wet
out without the application of substantial pressure of the at least
one polymer of the first blend component at said activating
temperature, and wherein the second molecular weight of the at
least one compound of said second blend component is sufficiently
low so that the at least one compound of the second blend component
exhibits sufficiently high molecular mobility to substantially
prevent processing the at least one compound of the second blend
component alone.
44. The polymeric bonding system of claim 43, wherein the polymeric
bonding system is in the form of an article selected from the group
consisting of fibrous materials, films, foams, coatings,
particulate materials, and combinations thereof.
45. A polymeric bonding system, comprising: an article comprising a
polymer blend capable of substantially wetting out a surface at a
flow activating temperature without requiring the application of
substantial pressure, said polymer blend further having blocking
resistance properties, said polymer blend comprising at least one
polymer having a first molecular weight and a glass transition
temperature T.sub.g, and at least one substantially crystalline
compound having a second molecular weight that is less than the
first molecular weight of the at least one polymer and having a
melting point that is greater than the T.sub.g of the at least one
polymer.
46. A polymeric delivery system, comprising: a polymer blend
capable of substantially wetting out a surface at a flow activating
temperature without requiring the application of substantial
pressure, said polymer blend further having blocking resistance
properties, said polymer blend comprising at least about 10 percent
by weight, based on the total weight of the polymer blend, of a
first blend component comprising at least one polymer having a
first molecular weight and at least about 10 percent by weight,
based on the total weight of the polymer blend, of a second blend
component comprising at least one compound having a second
molecular weight that is less than the first molecular weight of
the at least one polymer of the first blend component, wherein the
first molecular weight of the at least one polymer of said first
blend component is sufficiently high to prevent the substantial wet
out without the application of substantial pressure of the at least
one polymer of the first blend component at said activating
temperature, and wherein the second molecular weight of the at
least one compound of said second blend component is sufficiently
low so that the at least one compound of said second blend
component exhibits sufficiently high molecular mobility to
substantially prevent processing the at least one compound of said
second blend component alone; and at least one additive.
47. The polymeric delivery system of claim 46, wherein the
polymeric delivery system is in the form of an article selected
from the group consisting of fibrous materials, films, foams,
coatings, particulate materials, and combinations thereof.
48. The polymeric delivery system of claim 47, wherein the
polymeric delivery system comprises a fibrous material.
49. The polymeric delivery system of claim 48, wherein the fibrous
material is selected from the group consisting of continuous
filaments, staple fibers, yarns, tows, meltblown fibers, and
spunbonded filaments.
50. The polymeric delivery system of claim 47, wherein the
polymeric delivery system comprises a particulate material.
51. The polymeric delivery system of claim 50, wherein the
particulate material comprises a powder having an average diameter
of less than about 1 millimeter (mm).
52. The polymeric delivery system of claim 50, wherein the
particulate materials comprises a powder having an average diameter
of less than about 200 microns.
53. The polymeric delivery system of claim 46, wherein the at least
one additive comprises an additive selected from the group
consisting of antimicrobials, biocides, flame retardants, toxic
absorbers, conductive agents, abrasives, antioxidants, UV
stabilizers, optically active compounds, tracers, plating
catalysts, fungicides, mildewcides, phosphorescents, reflectants,
smart fabric components, polytetrafluoroethylene (PTFE),
repellants, particulates, reinforcing agents, fillers, pigments,
talc, glass fibers, clays, silicas, mineral silicates, mica, odor
absorbers, nano-particles, chemical deactivators, antistats,
markers, counterfeit tracers, fluorescents, ointments, and
combinations thereof.
54. A polymeric delivery system, comprising: a polymer blend
capable of substantially wetting out a surface at a flow activating
temperature without requiring the application of substantial
pressure, said polymer blend further having blocking resistance
properties, said polymer blend comprising at least one polymer
having a first molecular weight and a glass transition temperature
T.sub.g, and at least one substantially crystalline compound having
a second molecular weight that is less than the first molecular
weight of the at least one polymer and having a melting point that
is greater than the T.sub.g of the at least one polymer; and at
least one additive.
55. A composite article comprising: a matrix material; and a
polymer blend capable of substantially wetting out a surface of the
matrix material at a flow activating temperature without requiring
the application of substantial pressure, said polymer blend further
having blocking resistance properties, said polymer blend
comprising at least about 10 percent by weight, based on the total
weight of the polymer blend, of a first blend component comprising
at least one polymer having a first molecular weight and at least
about 10 percent by weight, based on the total weight of the
polymer blend, of a second blend component comprising at least one
compound having a second molecular weight that is less than the
first molecular weight of the at least one polymer of the first
blend component, wherein the first molecular weight of the at least
one polymer of said first blend component is sufficiently high to
prevent the substantial wet out without the application of
substantial pressure of the at least one polymer of the first blend
component at said activating temperature, and wherein the second
molecular weight of the at least one compound of said second blend
component is sufficiently low so that the at least one compound of
the second blend component exhibits sufficiently high molecular
mobility to substantially prevent processing the at least one
compound of the second blend component alone.
56. The composite article of claim 55, wherein the matrix material
is selected from the group consisting of fibrous materials,
cellulosic materials, and combinations thereof.
57. The composite article of claim 56, wherein the matrix material
comprises a fibrous material selected from the group consisting of
synthetic fibrous materials, natural fibrous materials, and
combinations thereof.
58. The composite article of claim 57, wherein the natural fibrous
material comprises cotton fibers.
59. The composite article of claim 58, further comprising an
antimicrobial agent.
60. The composite article of claim 56, wherein the matrix material
comprises a cellulosic material selected from the group consisting
of cellulosic fibrous materials, cellulosic particles, and
combinations thereof
61. The composite article of claim 55, wherein the polymer blend is
in the form of an article selected from the group consisting of
fibrous materials, films, foams, coatings, particulate materials,
and combinations thereof.
62. The composite article of claim 55, wherein the polymer blend
further comprises an additive.
63. A composite article comprising: a matrix material; and a
polymer blend capable of substantially wetting out a surface at a
flow activating temperature without requiring the application of
substantial pressure, said polymer blend further having blocking
resistance properties, said polymer blend comprising at least one
polymer having a first molecular weight and a glass transition
temperature T.sub.g, and at least one substantially crystalline
compound having a second molecular weight that is less than the
first molecular weight of the at least one polymer and having a
melting point that is greater than the T.sub.g of the at least one
polymer.
64. A chenille yarn comprising at least one core yarn and at least
one effect yarn, wherein said core yarn comprises a polymer blend
capable of substantially wetting out a surface at a flow activating
temperature without requiring the application of substantial
pressure, said polymer blend further having blocking resistance
properties, said polymer blend comprising a first blend component
comprising at least one polymer having a first molecular weight and
a second blend component comprising at least one compound having a
second molecular weight that is less than the first molecular
weight of the at least one polymer of the first blend component,
wherein the first molecular weight of the at least one polymer of
said first blend component is sufficiently high to prevent the
substantial wet out without the application of substantial pressure
of the at least one polymer of the first blend component at said
activating temperature, and wherein the second molecular weight of
said at least one compound of the second blend component is
sufficiently low so that the at least one compound of the second
blend component exhibits sufficiently high molecular mobility to
substantially prevent processing the at least one compound of the
second blend component alone, wherein said effect yarn is bound by
said polymer blend of said core yarn.
65. The chenille yarn of claim 64, wherein said polymer blend is
present in the form of one or more fibers blended with said core
yarn.
66. The chenille yarn of claim 64, wherein said core yarn comprises
a coating formed of said polymer blend.
67. The chenille yarn of claim 64, wherein said core yarn comprises
a multicomponent fiber comprising at least one component formed of
said polymer blend.
68. A polymer additive system comprising a water soluble additive
and a plurality of particles formed of a polymer blend capable of
substantially wetting out a surface at a flow activating
temperature without requiring the application of substantial
pressure, said polymer blend further having blocking resistance
properties, said polymer blend comprising a first blend component
comprising at least one polymer having a first molecular weight and
a second blend component comprising at least one compound having a
second molecular weight that is less than the first molecular
weight of the at least one polymer of the first blend component,
wherein the first molecular weight of the at least one polymer of
said first blend component is sufficiently high to prevent the
substantial wet out without the application of substantial pressure
of the at least one polymer of the first blend component at said
activating temperature, and wherein the second molecular weight of
the at least one compound of said second blend component is
sufficiently low so that the at least one compound of the second
blend component exhibits sufficiently high molecular mobility to
substantially prevent processing the at least one compound of the
second blend component alone.
69. The polymer additive system of claim 68, wherein said water
soluble additive comprises a flame retardant additive.
70. A waterborne coating system comprising a water soluble additive
encapsulated in a plurality of emulsified particles comprising a
polymer blend, wherein said polymer blend comprises a first blend
component comprising at least one polymer having a first molecular
weight and a second blend component comprising at least one
compound having a second molecular weight that is less than the
first molecular weight of the at least one polymer of the first
blend component, wherein the first molecular weight of the at least
one polymer of said first blend component is sufficiently high to
prevent the substantial wet out without the application of
substantial pressure of the at least one polymer of the first blend
component at said activating temperature, and wherein the second
molecular weight of the at least one compound of said second blend
component is sufficiently low so that the at least one compound of
the second blend component exhibits sufficiently high molecular
mobility to substantially prevent processing the at least one
compound of the second blend component alone.
71. A method of bonding an article, comprising activating a polymer
blend applied to an article to be bonded at a flow activating
temperature sufficient to substantially wet out a surface of the
article to be bonded with the polymer blend at said activating
temperature without the application of substantial pressure,
wherein said polymer blend has blocking resistance properties and
comprises at least about 10 percent by weight, based on the total
weight of the polymer blend, of a first blend component comprising
at least one polymer having a first molecular weight and at least
about 10 percent by weight, based on the total weight of the
polymer blend, of a second blend component comprising at least one
compound having a second molecular weight that is less than the
first molecular weight of the at least one polymer of the first
blend component, wherein the first molecular weight of the at least
one polymer of said first blend component is sufficiently high to
prevent the substantial wet out without the application of
substantial pressure of the at least one polymer of the first blend
component at said activating temperature, and wherein the second
molecular weight of the at least one compound of said second blend
component is sufficiently low so that the at least one compound of
the second blend component exhibits sufficiently high molecular
mobility to substantially prevent processing the at least one
compound of the second blend component alone.
72. A method of bonding an article, comprising activating a polymer
blend applied to an article to be bonded at a flow activating
temperature sufficient to substantially wet out a surface of the
article to be bonded with the polymer blend at said activating
temperature without the application of substantial pressure,
wherein said polymer blend comprises at least one polymer having a
first molecular weight and a glass transition temperature T.sub.g,
and at least one substantially crystalline compound having a second
molecular weight that is less than the first molecular weight of
the at least one polymer and having a melting point that is greater
than the T.sub.g of the at least one polymer.
73. A method of delivering an additive to an article, comprising
activating a polymer blend comprising an additive to be delivered
at a flow activating temperature sufficient to substantially wet
out a surface of an article to which the additive is to be
delivered at said activating temperature without requiring the
application of substantial pressure to effectively deliver the
additive to the article, wherein said polymer blend has blocking
resistance properties and comprises at least about 10 percent by
weight, based on the total weight of the polymer blend, of a first
blend component comprising at least one polymer having a first
molecular weight and at least about 10 percent by weight, based on
the total weight of the polymer blend, of a second blend component
comprising at least one compound having a second molecular weight
that is less than the first molecular weight of the at least one
polymer of the first blend component, wherein the first molecular
weight of the at least one polymer of said first blend component is
sufficiently high to prevent the substantial wet out without the
application of substantial pressure of the at least one polymer of
the first blend component at said activating temperature, and
wherein the second molecular weight of the at least one compound of
said second blend component is sufficiently low so that the at
least one compound of the second blend component exhibits
sufficiently high molecular mobility to substantially prevent
processing of the at least one compound of the second blend
component alone.
74. A method of delivering an additive to an article, comprising
activating a polymer blend comprising an additive to be delivered
at a flow activating temperature sufficient to substantially wet
out a surface of an article to which the additive is to be
delivered at said activating temperature without requiring the
application of substantial pressure to effectively deliver the
additive to the article, wherein said polymer blend comprises at
least one polymer having a first molecular weight and a glass
transition temperature T.sub.g, and at least one substantially
crystalline compound having a second molecular weight that is less
than the first molecular weight of the at least one polymer and
having a melting point that is greater than the T.sub.g of the at
least one polymer.
75. An activatable yarn comprising a plurality of fibrous material,
said fibrous material comprising a synthetic polymer having a first
molecular weight and a functionalized additive for promoting
adhesion of the synthetic polymer to another material and having a
second molecular weight that is less than the first molecular
weight of the synthetic polymer.
76. The activatable yarn of claim 75, wherein said synthetic
polymer comprising a polymer selected from the group consisting of
polyolefins, polyesters, polyamides, and combinations thereof.
77. The activatable yarn of claim 76, wherein said functionalized
additive comprises a maleic anhydride modified polyolefin.
78. The activatable yarn of claim 76, wherein said functionalized
additive comprises an amine functionalized additive.
79. The activatable yarn of claim 46, wherein said fibrous material
comprises at least one polymer having a first molecular weight and
a glass transition temperature T.sub.g, and a substantially
crystalline compound having a second molecular weight that is less
than the first molecular weight of the at least one polymer and
having a melting point that is greater than the T.sub.g of the at
least one polymer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to polymer blends and articles
including the same. More particularly, the present invention
relates to polymer blends having useful flow or wetting properties
without undesirable blocking properties and to products including
the same.
BACKGROUND OF THE INVENTION
[0002] Fibrous materials having various functionalities are useful
in many different applications. Often, it can be useful to treat a
fibrous material to impart or enhance a particular property
thereof, such as flame retardance, UV resistance, and the like.
[0003] The functionality of a fibrous material can be modified by
introducing a suitable additive into the fibrous structure. Many
natural fibers exhibit polar functionality (such as hydroxyl
functionality found in cotton fibers), due at least in part to the
biological origins of such materials. Nonetheless, functional
groups present in many natural fibrous materials can exhibit
limited reactivity, and accordingly, additive formulations can
simply sit in a bead and not wet out the substrate.
[0004] Natural (plant and animal) fibers can be blended with
synthetic fibers to formulate functionalized fibrous materials. The
differences in physical properties between synthetic and natural
fibers, however, can result in phenomena like pilling, which can
reduce the desirability and effectiveness of the blend. Other
treatments for imparting functionality to natural fibrous materials
may be limited to use with liquid vehicles. Yet, to penetrate a
fibrous material sufficiently to provide adequate bonding, the
fibrous materials are typically saturated with the liquid, which
results in a large volume of solution to be handled, removed from
the fabric, and disposed in compliance with environmental
regulations.
[0005] It can be difficult to introduce functional additives into
synthetic fibrous materials as well. For example, the crystallinity
of certain substrates, such as polypropylene fibrous articles, can
present a relatively hard, non-reactive surface to a would-be
binder. Many polyester copolymers such as are used as binders in
nonwoven fabrics also do not adhere well to polypropylene and/or do
not meet needed temperature-flow profiles. Further, the
effectiveness of an additive may depend on surface area
presentation. For example, silver antimicrobial agents operate via
release of silver ions. Yet such activity can be impeded if the
antimicrobial agent is buried deep within a treated synthetic fiber
or fabric. It can be difficult, however, to locate an active agent
on or near the surface of a synthetic fiber, and this difficulty
can be acerbated in applications dictating relatively minor amounts
of the active agent.
[0006] In addition to the issue of effectively introducing an
additive into a fibrous material, it can also be difficult to
impart permanency to the treated product. Topical treatments can
exhibit limited durability or can be readily reversed, particularly
when the fibrous material is exposed to washing, cleaning solvents,
and other environmental forces that the material itself may be able
to withstand, but a coating may not. Even for solvent based
additive systems, which can generally withstand numerous washings,
there is a desire to move away from solvent based systems due to
environmental concerns.
[0007] In addition, the additive carrier or binder should have
adequate thermal flow to allow it to be applied under commercially
feasible conditions and time frames, for example, at lower bonding
temperatures and/or residence times. Many polymer systems with high
molecular weights (which can be desirable for the requisite
physical properties) may lack flowability sufficient to penetrate
through a fibrous material. Accordingly, the use of high molecular
weight polymer systems may require the application of pressure,
such as by calendering. Further, high molecular weight polymer
systems may require relatively high bonding temperatures and/or
residence times, which can increase energy costs and bonding times
associated with using the same.
[0008] Polymers have been developed for use in applications
requiring relative good flow, such as hot melt adhesion and coating
applications. Such polymers can have relatively high melt flow
rates so as to impart desirable flow properties to the resultant
product. Such polymers, however, typically have lower molecular
weights, and thus can exhibit excessive molecular mobility and can
be generally tacky or block at normal warehousing and handling
conditions. Stated differently, products formed of polymers having
relatively high melt flow rates can become "sticky" or "tacky" and
thus tend to block, that is, to stick together, when subjected to
conditions of elevated temperatures and increased humidity, such as
associated with the commercial transportation and warehousing of
products. Such polymers can also stick to and bind up on processing
equipment, thereby decreasing manufacturing efficiencies.
[0009] Various techniques have been proposed to reduce the tendency
of high flow polymers to block. Anti-tack agents are offered
commercially to improve the block resistance of various polymers.
Although useful, many anti-tack agents are only marginally
effective, and further may be effective only with specific types of
polymers.
BRIEF SUMMARY OF THE INVENTION
[0010] The present invention is directed to polymer blends
exhibiting desirable flow properties without also exhibiting the
blocking properties typically associated with high flow polymers.
The polymer blends of the invention are capable of substantially
wetting out a surface at a flow activating temperature without
requiring the application of substantial pressure. Yet despite the
melt flow properties of the blends, the polymer blend after
applying and solidifying further exhibits blocking resistance
properties, thereby facilitating manufacturing and downstream
storage and transportation of products produced using the polymer
blends.
[0011] The polymer blends of the invention include at least two, or
more, components that differ from one another with regard to
molecular weight. The polymer blend includes a first blend
component including at least one polymer having a first molecular
weight and a second blend component including at least one compound
having a second molecular weight that is less than the first
molecular weight of the at least one polymer of the first blend
component. The molecular weight of the at least one polymer of the
first blend component is sufficiently high to prevent the
substantial wet out of the at least one polymer of the first blend
component without the application of pressure at the activating
temperature of the blend. The second molecular weight of the at
least one compound of the second component of the blend is
sufficiently low so that the at least one compound of the second
component of the blend exhibits a level of molecular mobility
sufficient to limit its usefulness by itself for the production of
an article such as a fiber or fabric. The at least one compound of
the second component of the blend may, for example, exhibit such a
high level of molecular mobility that when processed alone, its
usefulness is limited because it may be susceptible to blocking,
and/or because it may exhibit too much creep, and/or it may have
inadequate melt strength or viscosity to be processed. Yet together
the blend components can provide a combination of properties
including sufficient flow for fiber formation and/or wet-out of a
desired substrate without causing problems associated with blocking
or creep.
[0012] The polymer blends of the invention can be useful in the
production of products, such as binder fibers, that can be tailored
to exhibit a range of various properties, such flow rates,
activation temperatures, melt strengths, blocking temperatures, and
the like, depending on the desired application of the product. The
inventor has surprisingly found that polymer blends can be prepared
of at least two components having high and low molecular weights,
relative to one another, that can exhibit a melt strength that is
higher than expected given the resulting viscosity of the blend.
This is particularly surprising and useful in that it allows the
production of articles, such as fibers, from materials that can
have unusually low viscosity when remelted, as for instance when
used as a binder fiber. The invention accordingly can provide a
mechanism to fine tune polymer formulations for specific
applications.
[0013] In exemplary embodiments of the invention, at least one of
the components can include a substantially crystalline polymer,
which can promote a sharp flow profile. In other exemplary
embodiments of the invention, at least one of the components can
include a functionalized polymer component, such as a maleic
anhydride functionalized polyolefin, which can improve wetting
and/or adhesive properties of the blend. In yet other embodiments
of the invention, the polymer blend can include at least one
additive.
[0014] One exemplary polymer blend of the invention capable of
substantially wetting out a surface at a flow activating
temperature without requiring the application of substantial
pressure, the polymer blend further having blocking resistance
properties, can include at least about 10 percent by weight, based
on the total weight of the polymer blend, of a first blend
component including at least one polymer having a first molecular
weight and a glass transition temperature T.sub.g, and at least
about 10 percent by weight, based on the total weight of the
polymer blend, of a second blend component including at least one
substantially crystalline compound having a second molecular weight
that is less than the first molecular weight of the at least one
polymer of the first blend component and having a melting point
that is greater than the T.sub.g of the at least one polymer of the
first blend component. In this embodiment of the invention, at
least one of the first and second components can include a
functionalized polymer, such as a functionalized polyolefin,
including maleic anhydride modified polyolefins.
[0015] In other aspects, the present invention also provides a
polymeric bonding system and bonding methods using the same. The
polymeric bonding system of the invention can be in the form of an
article, such as a fibrous material, film, foam, coating, a
particulate material, and the like, formed of the polymer blend and
combinations thereof.
[0016] Other aspects of the invention are directed to a polymeric
delivery system and additive delivery methods using the same. The
polymeric delivery system of the invention can include the polymer
blend described herein in combination with an additive, and can
also be provided in the form of an article, such as a fibrous
material, film, foam, coating, a particulate material, and the
like. The polymer delivery system can be applied to a substrate and
treated (heated) to promote flow and form a coating. In this
embodiment of the invention, the coating can be relatively low add
on, can be substantially discontinuous (for example small islands)
or substantially continuous, and/or can be applied in a pattern by
various techniques. The coating may also be thin and/or flexible,
which can aid durability.
[0017] The polymer bonding system and the polymeric delivery system
of the invention and associated methods can be useful in the
production of various articles, including fibrous webs, yarns, and
the like and can secure additives to various substrates including
natural fibers having limited polar functionality.
[0018] Another aspect is directed to composite articles that
include a matrix material and the polymer blend of the invention.
The matrix material can be selected from fibrous materials, such as
synthetic and natural fibers, and cellulosic materials, such as
wood fibers and particles. The composite articles can further
include an additive. An exemplary embodiment of this aspect of the
invention includes an article formed of cotton fibers having an
additive, such as an antimicrobial additive, dispersed throughout
via fibers formed of a mixture of the polymer blend of the
invention and the antimicrobial additive.
[0019] Yet another aspect of the invention is directed to an
activatable yarn. The activatable yarn includes a plurality of
fibrous materials formed of a synthetic polymer having a first
molecular weight and a functionalized additive for promoting
adhesion of the synthetic polymer to another material and having a
second molecular weight that is less than the first molecular
weight of the synthetic polymer. Exemplary embodiments of this
aspect of the invention include polyolefin and polyester yarns
including a maleic anhydride modified polyolefin functionalized
additive or an amine functionalized additive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and in which:
[0021] FIG. 1 is a photomicrograph of particles of an exemplary
polymer blend material in accordance with the present
invention;
[0022] FIGS. 2A and 2B are photomicrographs illustrating
penetration of a polymer blend in accordance with the present
invention into a fibrous substrate;
[0023] FIGS. 3A and 3B are photomicrographs illustrating a fibrous
substrate following application of an exemplary polymer blend in
accordance with the present invention; and
[0024] FIGS. 4A, 4B and 4C are photomicrographs illustrating
droplet wicking of a polymer blend of the present invention along a
fiber surface.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention now will be described more fully
hereinafter in the following detailed description of the invention,
in which some, but not all embodiments of the invention are
described. Indeed, this invention may be embodied in many different
forms and should not be construed as limited to the embodiments set
forth herein; rather, these embodiments are provided so that this
disclosure will satisfy applicable legal requirements. As used in
the specification, and in the appended claims, the singular forms
"a", "an", and "the" include plural referents unless the context
clearly dictates otherwise.
[0026] The polymer blends of the present invention can have
desirable yet contradictory properties. The polymer blends can
exhibit wet out properties that can be useful in various
applications, yet surprisingly the inventor has also found that the
polymer blends of the invention can also exhibit desirable blocking
resistance (or anti-blocking) and durability properties as well.
The ability to formulate the polymer blends of the invention to
provide contradictory properties without significantly diminishing
the same is surprising in view of the tradeoffs typical in polymer
blending. That is, as will be recognized by the skilled artisan,
the properties of a polymer blend typically are not simply a linear
mixture of those of the constituent polymers, but rather the blend
properties that result are often inferior to that of a linear
prediction. For example, modifying the melt viscosity of a polymer
used in the production of hot melt adhesives by blending with
another polymer to reduce tackiness can negatively impact the
desired flow of the resultant product and render is useless for its
intended application. Conversely, blending a high melt strength
polymer with another polymer to improve flow properties can
similarly result in a product that no longer useful for its
intended purpose.
[0027] The polymer blends of the invention can substantially wet
out a surface at a given activating temperature without requiring
the application of substantial pressure. Stated differently, the
polymer blends of the invention are readily flowable under
activating temperature conditions without requiring the concurrent
application of pressure to promote or facilitate polymer flow. Yet,
despite the ready flow or wetting properties of the polymer blends
of the invention, in contrast to conventional flowable polymers,
the polymer blends of the invention do not exhibit substantial
blocking problems.
[0028] Reference herein to substantially "wetting out" a surface to
which the polymer blend is applied will be readily understood by
the skilled artisan and can be assessed using known techniques. In
exemplary embodiments of the invention, the polymer blend can
substantially wet out a surface to which is has been applied
without requiring the application of substantial pressure in about
one hour or less, and can be applied in as low as a few minutes
(for example, less than or about two minutes) at a selected
activating temperature, although the period for wetting a substrate
surface can fall outside of this range as well. As will be
appreciated by the skilled artisan, the term "wet-out" of a
substrate surface generally refers to contact angles of less than
about 90 degrees, or less than about 135 degrees, etc., which can
be evaluated, for example, using microscopy techniques. Sometimes
colorants are used in coating or binders to enhance the contrast.
The contact angle of an exemplary polymer blend of the invention is
illustrated, for example, in the droplet of FIG. 3.
[0029] The flow activating temperature can vary depending on
various factors but typically is a temperature ranging from about
100.degree. C. to about 150.degree. C., including flow activating
temperatures of about 125.degree. C., although polymer blends
exhibiting substantial wetting properties at activating
temperatures outside of this range can also be useful in accordance
with the present invention. As will be appreciated by the skilled
artisan, the term "activating temperature" as used herein refers to
the temperature at which the polymer blend will flow (for example,
the temperature at which the polymer blend in the form of a
coating, fabric or other article as discussed herein will flow) and
does not refer to the temperature of an oven, dye bath, etc.
through which the article may be passing.
[0030] In one exemplary embodiment of the invention, the polymer
blend can exhibit a flow activating temperature of about
100.degree. C. Such systems can be designed to exhibit very high
flow when the substrate to which the blend is applied, for example,
passes through a low temperature drying oven (i.e. enough heat to
drive off water), such as used with cotton or other natural fibers,
or is exposed to high temperature water or steam. The low
activating temperature can minimize discoloration (yellowing) that
can occur with cotton. The blends can flow substantially in high
temperature water conditions, such as that exhibited by many
conventional dye baths and/or at temperatures used in fabric drying
processes. The onset of softening can be well above 55.degree. C.
(131.degree. F.) so that the flow transition can be sharp to avoid
tackiness or blocking, for example, under hot summer conditions
normally encountered in warehousing and transportation. Thus,
despite the 100.degree. C. activating temperature, advantageously
in this embodiment of the invention, the resultant polymer blend is
not tacky and does not block above about 55.degree. C. This system
can have the highest flow relative to the two exemplary systems
described as follows and can be suitable for powdered delivery (for
example via foam, spray, slurry, and the like) to a substrate such
as a cotton fabric in applications for which flow under fabric
drying conditions and/or high temperature water conditions is
advantageous or required.
[0031] In another exemplary embodiment of the invention, the
polymer blend can exhibit a flow activating temperature of about
125.degree. C. Such systems can be substantially inert at boiling
water temperatures yet can flow well in an autoclave, for example.
Such systems can be suited for powdered delivery to a substrate,
such as a cotton fabric, in applications for which stability in hot
water, such as in washing, is advantageous or required.
[0032] In yet another exemplary embodiment of the invention, the
polymer blend can have an activating temperature of about
150.degree. C. Such systems can have higher melt strengths and
accordingly can be more readily melt spun to form a fibrous
article, such as a component of a multicomponent fiber or filament
(for example, a sheath component of a bicomponent sheath core
fiber). The resultant higher viscosity exhibited by the polymer
blends in accordance with this embodiment of the invention can
result in longer penetration times at temperatures of less than
150.degree. C. (for example about 125.degree. C.), but viscosity
can decrease at increasing temperatures, including temperatures
approaching 150.degree. C., and/or using finer dispersions of the
solid binder and/or more penetrating radiant energy for faster
heat-up. Such systems can be suited for delivery via bicomponent
fibers introduced into a substrate, for example, by blending the
bicomponent fibers with other fibers (natural fibers such as cotton
fibers and/or other synthetic fibers).
[0033] The polymer blends can be applied to any suitable substrate,
as discussed in more detail below. Suitable substrates can have
substantially smooth surfaces or can include a plurality of voids
or interstices (such as can be present along the surface of a
fibrous substrate) into which the polymer blend can flow and
substantially fill.
[0034] As used herein, the term "blocking" refers to the
"stickiness" or "tackiness" polymer products can exhibit when
exposed, either in the raw material state or after activation and
resolidification, to elevated temperatures and/or other
environmental conditions (such as humidity) during processing,
storage, and/or transportation. Blocking can be particularly
problematic in the storage and/or transportation of products formed
of readily flowable polymers that are subjected to extremes in
ambient temperature, humidity and other conditions that can result
in undesired adhesion of the products to one another, or to other
objects.
[0035] In contrast to many conventional flowable polymers, the
polymer blends of the invention exhibit block resistant (or
anti-blocking) properties, without requiring the addition of
substantial amounts of anti-blocking agents. The polymer blends of
the invention accordingly are not susceptible to developing a tacky
or sticky feel when cooled from elevated temperatures such as those
used in polymer processing or when packages or rolls are exposed to
expected extremes of temperature, humidity and other environmental
conditions to which a polymer product can be exposed during
transportation and storage.
[0036] As will be appreciated by the skilled artisan, blocking can
be evaluated using procedures known in the art. For example,
pellets or powder can be layered several deep in an aluminum pan,
which is then placed in a convection oven at a specified time for a
specified temperature. The skilled artisan will appreciate what
various test conditions, for example time, temperature, humidity,
and the like, to employ in analyzing blocking properties, based on
anticipated field use conditions that will be experienced. The
pellets are then removed from the oven and cooled. If the pellets
adhere to one another at all, they are judged to fail by
"blocking." Weight may be applied and blocking may appear only at
the bottom of a container. Long storage times and potential
humidity effects may also increase actual blocking behavior.
[0037] The uniform polymer blends of the invention can include at
least two, or more, different components, wherein at least two of
the components include one or more polymers or other compounds that
differ from one another with respect to the molecular weights of
the same. The polymer blends can include at least a first blend
component that includes at least one, or more, polymers having a
first molecular weight and at least a second blend component that
includes at least one, or more, compounds (which may or may not be
polymeric in nature) having a second molecular weight that is less
than the first molecular weight of the at least one polymer of the
first blend component. The respective blend components can also be
referred to as the higher molecular weight polymer component and
the lower molecular weight component. In exemplary embodiments of
the invention, the higher molecular weight blend component can
include at lease one or more polymers having a molecular weight
that is at least about three times, and up to about five times, or
more, higher than the molecular weight of at least one or more
compounds of the lower molecular weight blend component.
[0038] Although not wishing to be bound by any theory or
explanation of the invention, it is currently believed that the
blends take advantage of the fact that melt strength and melt
viscosity follow different functions of polymer molecular weight
distribution. The inventors have found combinations of high and low
molecular materials that can exhibit high melt strength or
elasticity as compared to the viscosity or resistance to flow also
exhibited by the blend. The resultant blends can flow well yet can
also be strong and can be spun into fibers.
[0039] The molecular weight of the one or more of the polymers of
the higher molecular weight blend component can be selected to
prevent the one or more polymers and/or the first blend component
from substantially wetting out a surface without the application of
substantial pressure under the same temperature conditions (flow
activating temperature) under which the polymer blend will
substantially wet out a surface, as discussed above. The higher
molecular weight polymer(s) can have a molecular weight ranging
from greater than about 6000 to about 50,000, and higher, number
average molecular weight, for example, from about 18,000 to about
30,000 number average molecular weight, although polymers having a
molecular weight outside of these ranges can also be useful in the
present invention so long as the higher molecular weight polymer
exhibits the wet out properties as discussed herein. The higher
molecular weight polymer component can be useful in imparting
desired melt strength to the polymer blends of the invention.
[0040] In various embodiments of the invention, the polymer(s) of
the higher molecular weight blend component is selected to have a
molecular weight that is sufficiently high to impart sufficient
melt strength to the blend to permit processing the polymer blend,
for example, to permit melt spinning, and quenching, the polymer
blend to form a desired product such as a fiber or fibrous
structure, including a component of a multicomponent fiber. As will
be appreciated by the skilled artisan, melt strength is commonly
measured by die-swell when a polymer is exuded from a capillary.
The practical manifestation is that molten streams in a spin
cabinet can be pulled without breaking, elongating to form
individual fibers.
[0041] The molecular weight of the one or more compounds of the
lower molecular weight component can be selected to be sufficiently
low so that the one or more compounds and/or the second blend
component exhibits a level of molecular mobility sufficiently high
so as to limit its usefulness for the production of an article such
as a fiber or fabric when processed alone and without combination
with another component. The one or more compounds and/or the second
blend component may, for example, exhibit too much molecular
mobility so that its usefulness alone is limited because it may be
susceptible to blocking, and/or because it may exhibit too much
creep, and/or it may have inadequate melt strength to be processed.
In various exemplary embodiments of the invention, the one or more
compounds of the lower molecular weight blend component can have a
number average molecular weight of about 6000 or less, for example
greater than 0 to about 6000 number average molecular weight, for
example greater than about 500 to about 6000 number average
molecular weight. Generally, the one or more compounds of the lower
molecular weight blend component cannot be spun onto a package
without blocking, using normal commercial fiber spinning
operations.
[0042] As will also be appreciated by the skilled artisan, creep or
cold flow of a polymer blend can be evaluated using an accelerated
test as follows. Pellets are loaded into a capillary rheometer such
is used for melt flow testing, and a specified weight is applied
(e.g. the standard 2.16 kg). The temperature is then ramped up in
gradual steps until the weighted piston begins to compress the
pellets. The temperature at which this happens is noted. Cold flow
can also be checked at ambient temperatures periodically, for
example, for 30 days, 60 days, etc.
[0043] In addition to the relative molecular weights of the
components of the blends of the invention, the blend components,
and one or more of the constituent polymers and/or compounds
thereof, can also differ with regard to melt flow rate (MFR), also
as determined using conventional test standards, such as ASTM
method D 1238B. In exemplary embodiments of the invention, the
higher molecular weight polymer component, and/or one or more of
its constituent polymer(s), can have a melt flow rate that is less
than the melt flow rate of the lower molecular weight component,
and/or one or more of its constituent compound(s). Stated
differently, the lower molecular weight component (and/or one or
more of its constituent polymers) of the polymer blend can have a
relatively high MFR as compared to the MFR of the higher molecular
weight polymer component (and/or one or more of its constituent
compounds).
[0044] As non-limiting examples, in exemplary embodiments of the
invention, the lower molecular weight component (and/or one or more
of its constituent compounds) can have a melt flow rate that is at
least about five times, and at least about ten times, or more,
higher than the melt flow rate of the higher molecular weight
polymer component (and/or one or more of its constituent polymers).
In other embodiments of the invention, the higher molecular weight
polymer component (and/or one or more of its constituent polymers)
can have a melt flow rate of about 1 decigrams per minute at a
temperature of about 125.degree. C. as determined in accordance
with ASTM method D 1238B, or less, and the lower molecular weight
component (and/or one or more of its constituent compounds) can
have a melt flow rate of about 100 decigrams per minute at a
temperature of about 125.degree. C. as determined in accordance
with ASTM method D 1238B, or more, although the invention is not so
limited and polymers having melt flow rates outside of these ranges
can be useful in accordance with the present invention.
[0045] The components, and/or one or more of the constituent
polymers and/or compounds thereof, of the blends of the invention
can also differ from one another with regard to melting point, as
determined using conventional test standards, such as differential
scanning calorimetry (DSC). In exemplary embodiments of the
invention, the higher molecular weight polymer component (and/or
one or more of its constituent polymers) can have a melting point
that is higher than the melting point of the lower molecular weight
component (and/or one or more of its constituent compounds). Stated
differently, the lower molecular weight component (and/or one or
more of its constituent compounds) of the polymer blend can have a
relatively low melting point as compared to the melting point of
the higher molecular weight polymer component (and/or one or more
of its constituent polymers). In exemplary embodiments of the
invention, the higher molecular weight polymer component (and/or
one or more of its constituent polymers) can have a melting point
of at least about 10.degree. C., for example, at least about
20.degree. C., and for example at least about 50.degree. C., or
more, higher than the melting point of the lower molecular weight
component (and/or one or more of its constituent compounds).
[0046] The melting point of the uniform polymer blend itself can
also vary, depending on various factors. In exemplary embodiments
of the invention, the melting point of the polymer blend can be
within about 20.degree. C. of the targeted blend application
temperature (i.e., the activating temperature). The inventor has
surprisingly found that the polymer blends exhibit the desired flow
properties described herein despite the presence of the higher
molecular weight component, which typically does not flow until
exposed to an "activating" temperature of at least about 50.degree.
C. or more above its melting point. Suitable polymer components
useful for providing a polymer blend with a melt temperature as
described herein can include substantially crystalline polymers, as
discussed in more detail below.
[0047] The molecular weight ranges of the blend components can vary
depending on a particular application or use of the blend and can
be readily determined by the skilled artisan. Various embodiments
of the invention can include blends of similar portions of two
materials with fairly extreme differences in flow (due to
crystallinity and/or molecular weight) yet are compatible and
provide synergistic properties in the blend. Such synergies can be
exhibited by sufficient melt strength/viscosity for fiber formation
and/or by a flow/tack sharp profile effect as discussed herein.
[0048] The polymer components of the polymer blends of the
invention can include any of the types of polymers suitable for the
formation of a particular article, i.e., can be any of the types of
polymer resins known in the art capable of being formed into
article such as fibrous materials (including without limitation
fibers, filaments, yarns, nonwoven articles, and the like, as
discussed herein), films (permeable and impermeable), foams,
sheets, coatings, particulate materials, and the like, as well as
combinations thereof. Examples of polymers useful in the practice
of the present invention include without limitation polyolefins,
including polypropylene, polyethylene, polybutene, and polymethyl
pentene; polyamides, including nylon 6 and nylon 6,6; polyesters,
including polyethylene terephthalate (PET), polyethylene
naphthalate (PEN), polytrimethylene terephthalate (PTT),
poly(1,4-cyclohexylene dimethylene terephthalate) (PCT),
glycol-modified polyethylene terephthalate (PETG), and aliphatic
polyesters such as polylactic acid (PLA); acrylics; thermoplastic
elastomers; polyacrylonitrile; acetals; fluoropolymers; epoxies;
phenoxies; vinyl alcohol polymers; polyesterimides; polyhydroxyl
alkanoates (PHA); polysulfone; polyetheretherketone; cellulose
acetate and rayons; polyurethanes; hot melt adhesives; and the
like, as well as co- and ter-polymers and ionomers of these and
other suitable polymers, and combinations thereof. Polyolefins can
be particularly advantageous in various embodiments of the
invention, although the invention is not limited to use of
polyolefins. Bio-based polymers which can be biodegradable made
from PLA and PHA can also be useful in various embodiments.
[0049] Hot melt adhesives can also be useful in various embodiments
of the invention. Hot melt adhesives are typically thermoplastic
polymers that are solid at room temperature and liquid at elevated
temperatures, for example, solid at temperatures below 180.degree.
F. and low viscosity fluids above 180.degree. F. Hot melt adhesives
set to a bond on cooling. Hot melt adhesives can include without
limitation paraffins, waxes, polyolefins, polyvinyl acetate
polyamides, ethylene vinyl acetate (EVA) copolymers,
styrene-isoprene-styrene (SIS) copolymers;
styrene-butadiene-styrene (SBS) copolymers; ethylene ethyl acrylate
copolymers (EEA); polyurethane reactive (PUR), and the like, and
combinations thereof.
[0050] Thermoplastic elastomers as known in the art can also be
useful in various embodiments of the invention. Exemplary
elastomers include without limitation polyurethane elastomeric
materials; polyamide elastomeric materials; polyester elastomers;
polyetherester elastomeric; polyetheramide elastomeric materials;
polyolefin elastomers; elastomeric styrene block copolmyers,
including diblock and triblock copolymers based on polystyrene (S)
and unsaturated or fully hydrogenated rubber blocks, which can
consist of butadiene (B), isoprene (I), or the hydrogenated
version, ethylene-butylene (EB); and the like and combinations
thereof.
[0051] Functionalized polymers can also be useful as one or more of
the components of the blends of the invention. The functionality
can be selected to provide a desired thermodynamic attractive force
between the polymer blend and the target substrate to which the
blend is applied, such as a natural fiber. This in turn can improve
wet out of the polymer blend.
[0052] The polymers can be functionalized as known in the art to
impart a desired property thereto, such as a functional group to
improve wet out and/or adhesion properties of the polymer component
and/or the resultant polymer blend. Exemplary functionally modified
polymers useful in various embodiments of the invention can
include, for example, various functionalized polyolefins, such as
but not limited to olefins modified by reaction with at least one
at least one unsaturated anhydride, unsaturated acid or unsaturated
ester. As non-limiting example, functionalized polyolefins useful
in the invention can include an olefin modified by reaction with at
least one unsaturated anhydride, unsaturated acid or unsaturated
ester selected from the group consisting of maleic anhydride,
citraconic anhydride, itaconic anhydride, glutaconic anhydride,
2,3-dimethylmaleic anhydride, maleic acid, fumaric acid, citraconic
acid, itaconic acid, mesaconic acid, glutaconic acid, acrylic acid,
methacrylic acid, crotonic acid, 2-pentenoic acid,
2-methyl-2-pentenoic acid, dimethyl malcate, diethyl maleatc,
di-n-propyl malcate, diisopropyl maleate, dimethyl fumarate,
diethyl fumarate, di-n-propyl fumarate, di-isopropyl maleate,
dimethyl itaconate, methyl acrylate, ethyl acrylate, methyl
methacrylate, ethyl methacrylate, methyl crotonate, and ethyl
crotonate. Polymer blends including one or more maleic anhydride
modified olefins, including without limitation maleic anhydride
modified polypropylene and maleic anhydride polyethylene, can be
particularly useful in various applications. As will be appreciate
by the skilled artisan, some of these functionalities can also be
created by oxidizing an olefin, and other exemplary polymers
include polymers functionalized by oxidizing the polymer, for
example, by oxidizing a polyolefin.
[0053] Non-limiting examples of functionalized polymers useful in
the present invention include maleated polyethylene commercially
available from Dow Chemical and maleated waxes such as the Epolene
waxes commercially available from Eastman Chemical Company. Also
useful are polymeric or non-polymeric compounds having one or more
carboxyl, hydroxyl, and/or amine functional groups. In this
embodiment, the lower molecular weight component can include one or
more substantially crystalline or semicrystalline functionalized
compounds, which can also be lower molecular weight compounds that
have a melting point that is higher than the T.sub.g of at least
one polymer of the higher molecular weight component of the blend.
Although not wishing to be bound by any theory or explanation of
the invention, it is currently believed that the increased
functionality imparted to the blends by incorporating such
functionalized polymers can increase wet-out and improve adhesion
to cellulosics, cotton, and other natural fibers, as well as
synthetic fibers spun from acrylic, nylon, and other polar
polymers.
[0054] At least one or more of the components of the polymer blends
of the invention can include a substantially crystalline or
semicrystalline polymer. Various embodiments of the invention can
include, for example, at least one or more substantially
crystalline low molecular weight polymer component(s). The term
"substantially crystalline or semicrystalline" is understood in the
polymer art and as used herein refers to a material's inherent
ability to crystallize when referring to material type, or
alternatively its current state of crystallinity when referring to
a particular product or object, as determined using conventional
techniques as known in the art. Methods for determining the degree
of crystallinity of a polymer are known in the art and include, for
example, DSC, density gradient tubes, and x-ray diffraction
techniques. Generally as used herein, the term crystalline or
semicrystalline refers to materials having a melt peak on DSC with
at least about 5 J/g of material, or more, for example, at least
about 10 J/g material or more. As non-limiting examples, polyesters
cay exhibit a melt peak on DSC of about 30 to about 50 J/g and
olefins can exhibit a melt peak on DSC of up to about 100 J/g.
[0055] The addition of a substantially crystalline polymer
component, including a low molecular weight substantially
crystalline polymer component, can promote the flow of the polymer
blend at low temperatures without blocking or fusing. The addition
of one or more substantially crystalline low molecular weight
polymers can, for example, result in a blend having a melting point
within about 20.degree. C. of the targeted blend application
temperature (i.e., the activating temperature, which can be, for
example, about 125.degree. C. or less).
[0056] In exemplary embodiments of the invention, the low molecular
weight component includes a substantially crystalline polymeric or
non-polymeric component (also referred to herein as a substantially
crystalline plasticizer). In this embodiment of the invention, the
substantially crystalline low molecular weight component can have a
melt point (T.sub.m) that is higher than the glass transition
temperature T.sub.g of the higher molecular weight polymer
component of the blend. Again, although not wishing to be bound by
any explanation of the invention, it is currently believed that the
use of such materials in the blend can result in sharp flow
profiles. The polymer blend of this embodiment of the invention can
be in any of the various forms discussed herein, including fibers,
nonwoven fabrics, coatings, and the like. An exemplary blend in
accordance with this embodiment of the invention can include
phenoxy having a T.sub.g as the high molecular weight component and
a substantially crystalline component (plasticizer) having a
T.sub.m that is higher than the T.sub.g of the phenoxy component,
and the like, including combinations thereof.
[0057] Each of the components can be present in the polymer blend
of the invention in an amount sufficient to impart the desired
wetting and blocking resistance properties thereto. In exemplary
embodiments of the invention, the blend can include at least about
10 percent by weight of one, or both, of the higher molecular
weight and the lower molecular weight components. For example, the
polymer blends of the invention can include at least about 20
percent by weight, at least about 30 percent by weight, at least
about 40 percent by weight, and at least about 45 percent by
weight, based on the total weight of the polymer blend, of one or
both of the higher and lower molecular weight components.
[0058] The skilled artisan will realize that the respective first
and second components of the polymer blends of the invention can
include at least one, or a blend or more than one, component
thereof. For example, the first component of the polymer blend can
include at least about 10 weight percent of one polymer or can
include at least about 10 weight percent of a blend of two or more
polymers, in accordance with the present invention (in which case,
the first blend component can include less than 10 weight percent
of a particular polymer of the polymer blend). Similarly, the
second component of the polymer blend can include at least about 10
weight percent of one compound or can include at least about 10
weight percent of a blend of two or more such compounds (in which
case, the second blend component can include less than 10 weight
percent of a particular compound or component thereof). As used
herein, the term "compound" in reference to the second blend
component can include polymeric and non-polymeric compounds.
[0059] In embodiments including a blend of polymers as the first
blend component, one or more of the polymers can meet one or more
of the criteria of molecular weight, T.sub.g, etc., as discussed
herein. Similarly, in embodiments including a blend of compounds as
the second blend component, one or more of the compounds can meet
one or more of the criteria of molecular weight, T.sub.m, etc., as
discussed herein.
[0060] In other embodiments of the invention, the polymer blend can
further include at least one additive, as discussed herein, in
about a 1:1:1 ratio high molecular weight polymer component:low
molecular weight component:additive, although as discussed herein
additives when present can be present in amounts outside of this
range.
[0061] The polymer components, and additives when present, can be
present in amounts outside of these ranges as well. Surprisingly,
however, the inventors have found that relatively high amounts (at
least about 10 percent by weight, and more, up to 50 percent) of
the low molecular weight component (which can have a melt flow rate
in the thousands) can be included in the polymer blends of the
invention without substantially decreasing the blocking resistance
of the polymer blend and also without significantly decreasing the
processability of the polymer blend. Similarly, the inventors have
surprisingly found that the polymer blends can include relatively
high amounts (at least about 10 percent by weight, and more) of the
high molecular weight polymer component without significantly
reducing the flow or wetting properties of the blend as described
herein.
[0062] The polymer components can blended with one another using
conventional mixing techniques. In exemplary embodiments, the
polymer components can be dry blended with one another prior to
melting the polymers in subsequent extrusion or other polymer
processing steps. In other exemplary embodiments, separate polymer
melts can be combined with one another, for example, as polymer
melts pass through an extruder.
[0063] The polymer blends of the invention can further include at
least one, or more, additives mixed or blended therewith. Such
embodiments of the invention can be useful, for example, as
additive delivery systems, as discussed in more detail herein.
Exemplary additives useful in the present invention can include
without limitation antimicrobials, biocides, flame retardants,
toxic absorbers, conductive agents, abrasives, antioxidants, UV
stabilizers, optically active compounds, tracers, plating
catalysts, particulates, reinforcing agents, fillers, pigments,
talc, glass fibers, clays, silicas, mineral silicates, mica, odor
absorbers, nano-particles, chemical deactivators such as activated
carbon, antistats, markers, counterfeit tracers, fluorescents,
fungicides, mildewcides, phosphorescents, reflectants, "smart
fabric" components, polytetrafluoroethylene (PTFE), repellants,
ointments, and the like, and combinations thereof. The invention
allows the ready application of a wide ranging amounts of additives
and can be particularly useful in the application of very low
amounts of additives. The invention can be useful for applying a
very small amount of additive substantially uniformly to a
substrate with durability. The resultant layer can in many
instances be just a few microns thick as well so that the particle
size of the additive can be very small. This can be useful in many
applications in which the additive particles might otherwise be
buried below the skin of a synthetic fiber.
[0064] For example, silver and/or copper based antimicrobials can
be introduced into a suitable substrate in accordance with the
present invention. Such antimicrobials can be particulate in nature
to promote controlled release of the active agent yet typically
must also be near the surface of a substrate (such as a fiber) to
function. Typically, a relatively low amount of the antimicrobial
agent can be effective. The present invention can allow the
introduction of relatively small quantities of such antimicrobial
agents into a suitable substrate, such as a surface of a fiber, for
use in numerous applications, including without limitation health
care products such as hospital sheets, gowns, draperies, and
mattresses to help control secondary infections; and sports or
athletic wear to help reduce odors from bacteria and mildew. More
uniform distributions can be achieved by dispersion using such a
vehicle when the additive level is low, such as but not limited to
the 0.01 to 0.1% range.
[0065] Odor absorbing agents such as activated carbon can also be
effectively introduced into a suitable substrate in accordance with
the present invention. Similar to silver and copper antimicrobial
agents, particulate odor absorbing agents can be more effective
when held at the surface of the substrate (such as a fiber
surface). The present invention can allow the introduction of
effective amounts of odor absorbing agents into a suitable
substrate, such as a fiber surface, to help in protecting freshness
in sportswear, among other applications.
[0066] Similarly, nano-particles and other additives useful, for
example, in the deactivation of chemical agents can also be
introduced into a suitable substrate in accordance with the present
invention. The resultant products can be useful in military,
industrial, and homeland security applications.
[0067] Flame retardant agents are another non-limiting example of
the types of active agents that can be introduced to a suitable
substrate in accordance with the present invention. For example,
particles that expand when heated to flame temperatures could be
used to bolster intumescent flame retardant systems and could be
affixed to fabrics in accordance with the present invention. The
flame retardant particles can also be a part of multicomponent
flame retardant systems such as discussed in copending and commonly
assigned U.S. application Ser. No. 11/369,252, filed Mar. 7, 2006,
the entire disclosure of which is hereby incorporated by reference.
Non-limiting examples of flame retardant additives suitable for use
in accordance with the present invention include, for example,
melamine cyanurate, boric acid and boron containing salts,
halogens, antimony compounds, ammonium polyphosphate, melamine
polyphosphate, phosphorous compounds, hydrates such as aluminum
trihydrate, expanded graphite, char-inducing catalysts, and the
like and combinations thereof.
[0068] As yet another non-limiting example, taggant or tracer
additives can be adhered to a suitable substrate in accordance with
the present invention. Such taggant or tracers for fabric, paper
and other products can be useful, for example, to audit the source
of fabrics, to help control counterfeiting, and the like. In other
non-limiting examples, many optical markers such as fluorescent or
phosphorescent agents typically function at relatively high
concentrations. Using the present invention, such agents can be
made visible at lower concentrations by the increased efficiencies
of concentrating the agents into localized regions of a suitable
substrate where they are delivered by a polymer blend of the
invention.
[0069] The present invention is not limited to these applications.
The formulated systems of the invention can have the additional
benefit of having inherently low color. This mask surface
imperfections of a substrate to which the polymer blend is applied,
such as that on a natural fiber, which in turn can reduce dullness
and create a "wetter," silkier look.
[0070] These and other additive(s) can be incorporated into the
polymer blends of the present invention using conventional
techniques. The additive(s) can independently blended with one or
more of the polymer components and/or can be added to the polymer
blend. In exemplary embodiments, the additive(s) can be dry blended
with one or more of the polymer components of, and/or with the
polymer blend itself, prior to melting the polymer components
and/or the resultant polymer blend in subsequent extrusion or other
polymer processing steps. The additive(s) can also be added to
melts of the polymer components and/or of the polymer blend, for
example, as the polymer component and/or polymer blend melt(s) pass
through an extruder. A masterbatch of one or more polymer
components and/or the polymer blend of the invention and the
additive(s) can also be prepared and added to the polymer
components and/or polymer blend in dry or melt form. The
additive(s) can be used in the invention in various forms,
including powder, liquid and melt forms, as appropriate for a given
application.
[0071] Other aspects of the invention include polymeric bonding
systems and polymeric additive delivery systems that include the
polymer blends of the invention as a component thereof, as well as
methods of using the same. In these and other aspects of the
invention, the polymer blends can be provided in any form useful
for a particular end application, including without limitation, in
the form of a fibrous material, film (including co-extruded films,
permeable films, impermeable films), foam, sheet, coating, a
particulate material, and the like, and combinations thereof.
[0072] The polymer blends of the invention can be particularly
useful as additive delivery systems to impart additive
functionality to a substrate, including cotton and other natural
fibers. The polymer blends can be suited for uniformly dispersing
and binding particulate additives to a substrate, durably anchoring
the additive to the substrate, for example via a thin flexible
coating, to optimize placement and maximize performance. As noted
herein, the polymer compositions of the invention can have sharp
flow profiles with improved flow at lower temperatures for bonding.
Yet the polymer blends are not tacky or prone to block at normal
extremes of temperature exposure during transporting and
warehousing. The polymer blends can be used to deliver
discontinuous deposits (for example small islands) or a
substantially continuous yet breathable network that coats and
bridges the surface layer of the substrate (such as the surface of
fibers) in a construction. In addition, the polymer blend additive
systems can exhibit the permanence of a thermoplastic but can be
applied to a substrate at very low levels with good penetration and
dispersion.
[0073] As used herein, the term "fibrous material" includes fibrous
articles such as but not limited to staple fibers, continuous
filaments, yarns, tows, fiber bundles, bulked continuous filament
(BCF), staple fiber spun yarns, twisted yarns (i.e., 2 or more
yarns twisted together), wrapped yarns, sewing thread, meltblown
fibers, spunbonded filaments, nowoven fabrics, woven fabrics, knit
fabrics, and the like, as well as combinations thereof. In general,
staple, multifilament, and spunbond fibers in accordance with the
present invention can have an equivalent diameter of about 0.5 to
about 100 denier. Meltblown filaments can have a diameter of about
1 to about 5 microns. The fibers can also be monofilaments, which
can have a fineness ranging from about 20 to about 5,000
denier.
[0074] For ease of discussion, the term "fiber" as used herein can
refer both to fibers of finite length, such as conventional staple
fiber, as well as substantially continuous fibrous structures, such
as continuous filaments, unless otherwise indicated. The term fiber
as used herein can also include crimped, uncrimped, and textured
fibers and filaments, including bulked continuous filaments (BCF)
and filament tows as well. The fibers of the invention can be
hollow or non-hollow fibers, and further can have a substantially
round or circular cross-section or non-circular cross-section (for
example, "shaped fibers" or fibers with shaped cross-sections, such
as but not limited to oval fibers, rectangular fibers, multi-lobed
or lobal fibers, delta cross-sections, and the like).
[0075] When the polymer blends of the invention are in the form of
a fiber, the fibers can be monocomponent fibers or multicomponent
fibers, in which at least one, or more, components thereof includes
the polymer blend of the invention. At least one or more components
can be dissolvable. The multicomponent fibers can have a variety of
fiber configurations as known in the art so long as the fiber
components are arranged so as to form distinct cross-sectional
segments along at least a portion of the length of the fiber. The
multicomponent fibers can include substantially non-occluded
segments, such as those present in pie/wedge fibers, side-by-side
fibers, segmented round fibers, segmented oval fibers, segmented
rectangular fibers, segmented multilobal fibers, and the like. The
present invention is not limited to non-occluded fiber
constructions, and accordingly other fiber configurations are
included within the scope of the present invention, including those
in which at least a portion of a one fiber segment is partially or
fully occluded by an adjacent segment, such as found in islands in
the sea fiber constructions, sheath core fibers, and the like. The
multicomponent fibers of the invention further can be splittable,
i.e., capable of separating into microfilaments upon appropriate
chemical and/or mechanical action. Alternatively, the
multicomponent fibers of the invention can be substantially
nondissociable.
[0076] Nonwoven fabrics useful as the fibrous materials of the
invention can be made according to any of the known commercial
processes for making nonwoven fabrics, including processes that use
mechanical, electrical, pneumatic, or hydrodynamic means for
forming or assembling fibers into a web, for example carding,
wetlaying, air laying, spunbonding, meltblowing, and the like. The
webs can be bonded using techniques as known in the art, such as
but not limited to mechanical bonding, such as hydroentanglement
and needle punching, adhesive bonding, thermal bonding, and the
like, to form a coherent and useful fabric structure. An example of
thermal bonding is through-air bonding, although other thermal
bonding techniques, such as calendering, microwave or other RF
treatments can be used. Other textile structures such as but not
limited to woven and knit fabrics and tufted carpets and yarns
prepared for use in forming such woven and knit fabrics and tufted
carpets are similarly included within the scope of the present
invention. Nonwoven-containing articles similarly include but are
not limited to hygiene, safety masks, filter media, footwear
components and furniture backing. In tufted carpets, the coatings
of the invention can be useful in applying antimicrobials and other
consumer pleasing functionalities, as well as improving tip
definition and wear properties.
[0077] As used herein, the term "particulate materials" can include
a plurality of particles formed of the polymer blends of the
invention. Exemplary embodiments of the invention include polymer
blends in the form of finely reduced powders having average
diameter of less than about one millimeter (mm), and finely divided
powder having an average diameter of less than about 200 microns,
for example from about 20 to about 200 microns, although the
present invention is not so limited and particulate material having
an average diameter outside of these ranges can also be useful in
the present invention.
[0078] The polymeric additive delivery systems of the invention can
further include one or more additives as a component thereof, as
described herein. The additives can be substantially uniformly
mixed with the polymer blend so that the additive is substantially
uniformly distributed throughout the delivery system (for example,
substantially uniformly distributed throughout a staple fiber
formed of an admixture of the polymer blend and one or more
additives). Alternatively, the additive can be substantially
non-uniformly distributed in the additive delivery system. As a
non-limiting example of this embodiment of the polymeric delivery
systems of the invention, the additive can be present along a
surface of a fiber formed of the polymer blend, which can result
from "blooming" of the additive to the article surface under
suitable conditions.
[0079] In this aspect of the invention, additives can be delivered
within a matrix, such as a fibrous system, even if the polymer
blend is not present in sufficient quantity to significantly bond
the matrix fibers together. In this manner, the present invention
can provide a mechanism for introducing an additive into a matrix
material by activating the blend and allowing the polymer blend
spread out and coat the matrix materials. The relatively low flow
temperature of the polymer blends of the invention may provide the
additional advantage of allowing the use of temperature-sensitive
additives that might not survive incorporation into higher melt
temperature synthetic fibers.
[0080] The polymeric bonding systems and polymeric additive
delivery systems in accordance with these aspects of the invention
can be useful in the production of various products, including
without limitation, fibrous articles, laminates, composites, and
the like, as well as combinations thereof. The articles of the
invention including the polymer blend as a component thereof can be
generally described as including a matrix material and the polymer
blend, per se or in the form of a polymeric bonding system,
polymeric additive delivery system, or the like, as described
herein.
[0081] As used herein, the term "matrix material" refers generally
to the material to which the polymer blend is applied or blended
with to achieve bonding, additive delivery or other functional
aspects of the present invention. In various exemplary embodiments
of this aspect of the invention, articles including the polymer
blends of the invention can be referred to generally as "composite
articles" to indicate that the articles include a combination of
two or more materials, including the polymer blend of the invention
and another material (i.e., the matrix material as defined herein),
that differ in form or composition. The constituent components of
the composite articles of the invention may, but are not required
to, retain their identities, be physically identified and exhibit
an interface between one another.
[0082] Non-limiting examples of the types of matrix materials that
may be useful in the production of the articles of the invention
include fibrous materials (including synthetic fibers and natural
fibers, such as plant fibers and animal fibers), cellulosic
materials, laminates, composites, polymeric resins, foams, and the
like, as well as combinations thereof. The matrix materials can
have different functions, including support, reinforcement, filler,
binder, and the like, as well as combinations of these
functions.
[0083] Exemplary fibrous materials useful as matrix materials of
the composite articles of the invention include any of the types of
fibrous materials described herein. As an example, the polymer
blend (for example in the form of staple fibers or particulate
material, optionally in combination with an additive) can be
applied to and/or intermixed with a plurality of staple fibers
formed of a different polymer composition to form a nonwoven web.
The staple fibers can include synthetic and/or man-made fibers,
natural fibers, and/or blends of the same. Exemplary synthetic
fibers include without limitation acrylic fibers, polyolefin
fibers, polyester fibers, polyamide fibers, and the like, as well
as blends thereof with one another and/or with natural fibers.
Exemplary natural fibers include without limitation cotton fibers,
wool fibers, and the like, as well as blends thereof with one
another and/or with synthetic fibers. Fibrous materials can be
utilized separately, further incorporated into multilayer
constructions such as laminates or composites, or be used as
coating substrates within the scope of the invention.
[0084] In this embodiment of this aspect of the invention, the
resultant web can be subjected to activation temperature conditions
sufficient to promote substantially wetting of the staple fibers or
particulate material formed of the polymer blend of the invention
within the web sufficient to bond the staple fibers to form a
substantially coherent structure and/or to distribute an additive
within the fabric structure. The present invention can provide an
advantageous mechanism for delivery of an additive, such as an
antimicrobial agent, to a fibrous structure, such as a web
including a plurality of cotton fibers.
[0085] As a non-limiting example, a fiber containing the polymer
blend of the invention in which are imbedded antimicrobial
particles (such as silver or copper compounds) is blended with
cotton fibers, for example, during a carding process. The resultant
mixture can be heat treated under conditions sufficient to activate
the polymer to wet out and coat the cotton fibers and thus deliver
the antimicrobial agent within the cotton article to provide a
cotton article with antimicrobial properties. The high flow of the
polymer blend can allow the use of a relatively small amount of
synthetic fiber to treat a larger volume of cotton. The relatively
low activation temperature of the polymer blends can further
advantageously minimize discoloration that can occur when heat
treating cotton fibers at relatively high temperatures.
[0086] The polymeric bonding systems and/or polymeric additive
delivery systems of the invention can also be useful in the
production of other fibrous articles, including products requiring
relatively deep penetration of an adhesive into the article, such
as may be the case for many tuft-locks on carpet, scatter rugs,
automotive flooring, and the like. The polymeric bonding systems
and/or polymeric additive delivery systems of the invention can
also be useful in various hot melt applications, such as anti-slip
coatings on carpets and other flooring materials, which can benefit
from improved flow and sharper flow profiles (and thus faster
operation in industrial application) as compared to traditional hot
melt adhesives. In still other applications, the polymeric bonding
systems and/or polymeric additive delivery systems can be useful as
coatings for yarns and other fibrous materials to reduce hairiness,
pilling, minimize yarn pullout, increase strength, and to improve
abrasion resistance.
[0087] The polymeric bonding systems and/or polymeric additive
delivery systems of the invention can also be useful in the
production of other fibrous articles such as chenille yarns, felt,
other wrapped yarns, and the like. In these types of products, the
adhesive delivery system must bond fibers many fiber diameters
removed from where the binder is applied, and accordingly flow
characteristics can be increasingly important for the performance
of the end product. The present invention can provide such bonding
and further can improve carpet yarn timp definition and wear
aesthetics. For example, in the manufacture of chenille yarn,
typically twisted pairs of a core yarn hold in place bundles of
"effect" yarn at an angle substantially perpendicular to the core
yarn. A binder applied via the core yarn advantageously has enough
flow to penetrate to a depth of dozens of fiber diameters, yet stop
short of wicking out the length of the effect yarn and so causing
it to stiffen. In one embodiment of the invention, the polymer
blends of the invention can be incorporated as a part of one or
more core yarns. The polymer blend may be incorporated into the
core yarn using any suitable techniques, such as blending fiber
formed of the polymer blend with the core yarn, coating the core
yarn with the polymer blend, and/or incorporating the polymer blend
as a component in a multicomponent core fiber.
[0088] As another non-limiting example, the matrix materials can
include any of the types of cellulosic materials known in the art,
such as but not limited to wood particles, wood fibers, fluff pulp
(such as can be used in disposable absorbent articles such as
diapers), cellulose acetate fibers, cotton, flax, and the like and
mixtures thereof, and can be useful in the production of paper
products, including wipes. In this embodiment of this aspect of the
invention, the polymer blend (for example in the form of staple
fibers or particulate material, optionally in combination with an
additive) can be applied to and/or intermixed with a plurality of
wood fibers or particles and the resultant mixture can be subjected
to activation temperature conditions sufficient to promote
substantially wetting of the staple fibers or particulates formed
of the polymer blend of the invention within the article sufficient
to bond the wood fibers or wood particles to form a substantially
coherent structure and/or to distribute an additive within the
coherent structure. In exemplary embodiments, the length scale of
bonding may be limited to that area around neighboring fibers and
the flow requirement may be low. The present invention can be
helpful in such application to control the bonding temperature to a
desired processing target, and insure good wet-out and bonding. The
present invention can also be useful for incorporating and/or
delivering various additives, including additives capable of
improving insect resistance and/or mildew resistance.
[0089] As yet another non-limiting example, the invention can
include an additive delivery system including a water soluble
additive, such as but not limited to a water soluble flame
retardant. The polymer additive system of this embodiment of the
invention can further include a polymer blend of the invention,
which can be in any suitable form, for example, as a plurality of
fine particles. The additive delivery system in accordance with
this embodiment of the invention can be useful in emulsion type
coatings, such as acrylic coatings. As a non-limiting example, the
additive delivery system can be a waterborne coating system
including include a water soluble additive, such as a water soluble
flame retardant, encapsulated in a plurality of emulsified
particles formed of the polymer blend of the invention. In various
embodiments including a water soluble flame retardant additive, the
additive delivery system may not see melt conditions until exposed
to flame conditions (as contrasted to the manufacturing process),
and the additive can thus be dispersed when an article on which the
coating is applied is exposed to flame conditions and burns.
Otherwise, the additive may still be "locked up" in the particles
embedded in the coating. The invention can also be useful as a part
of a A-B type dual layer coating (base and top coating) or A-B film
system, in which A includes at least one flame retardant component
and B includes another flame retardant component.
[0090] The blend of the invention can be present in the composite
articles in varying amounts, depending upon various factors, such
as the application of the resultant product, desired degree of
bonding, aesthetics, and the like and can be readily determined by
the skilled artisan. Generally, the polymer blend in the form of
fibers, particulates, etc. can be present in the composite article
in an amount ranging from about 1 to about 25 percent by weight,
although the polymer blend can be present in amounts outside of
this range as well.
[0091] In these and other embodiments of this aspect of the
invention, the blend in the form of staple fibers, particulate
material, and the like, can be applied to and/or mixed with a
desired matrix material, and the resultant mixture can be subjected
to a suitable activation temperature to activate wet out of the
binder fibers and/or particulate materials. Although the polymer
bonding system of the invention has been described herein with
reference to staple fibers and particulate materials, the present
invention is not so limited, and as indicated herein, the polymer
bonding systems can also be in other forms such as a coating (for
example one or more extrusion coated layers) applied to an article
to bonded, as a film, sheet material, and the like.
[0092] Yet another aspect, the present invention includes
activatable yarns. In this aspect of the invention, yarns formed of
a suitable polymer, typically with limited reactivity such as many
polyolefins and polyesters, can include a functionalized additive,
typically having a lower molecular weight that the polymer of the
yarn. The polymer and functionalized additive of the activatable
yarns can each be present in the yarn in amounts of at least about
10 percent by weight, at least about 20 percent by weight, at least
about 30 percent by weight, at least about 40 percent by weight,
and up to at least about 50 percent by weight, and higher, based on
the total weight of the yarn. The yarn can further include other
additives such as those discussed herein in amounts also as
discussed herein.
[0093] The functionalized additive can act as an "activating agent"
to promote adhesion of the yarn and can be selected based at least
in part upon the nature of an adhesive to be used with the yarn.
The functionalized additive can be incorporated into the polyolefin
or polyester yarn using any suitable technique, such as blending
fiber formed of the functionalized additive with the yarn, coating
the yarn with the functionalized additive, and/or incorporating the
functionalized additive as a component in a multicomponent fiber.
The functionalized additive can be incorporated into other
synthetic polymers, such polyamides and modified celluloses.
[0094] A non-limiting example of an activatable yarn in accordance
with this aspect of the invention includes a polyolefin or a
polyester yarn having a maleic anhydride modified polyolefin
incorporated therein. Activation of the maleic anhydride modified
polyolefin can promote bonding of the polyolefin and/or polyester
yarn using a nylon-based adhesive. Another non-limiting example of
an activatable yarn in accordance with this aspect of the invention
includes a polyolefin or polyester yarn having an amine
functionalized additive, such as stearamide, incorporated therein
as the functionalizing additive. Activation of the stearamide can
promote bonding of the yarn using an acid functional binder.
[0095] The present invention will be further illustrated by the
following non-limiting examples.
COMPARATIVE EXAMPLE
[0096] Several samples of ethylene methacrylate (EMAC) adhesive
polymers having different molecular weights are evaluated to try to
develop improved flow for better wet-out. The materials are tacky
and block badly, even at molecular weights that still are not low
enough to flow at a significantly reduced temperature.
COMPARATIVE EXAMPLE
[0097] A maleated polypropylene wax such as that commercially
available from Eastman Chemical as Epolene E-43 is blended in
amount of 5 to 10% into a polyethylene or polypropylene resin. This
material can be spun, the maleic acid functionality can provide
adhesive properties, and the blend can provide a binder for
applications requiring little flow. The bulk and rheological
properties of the blend, however, remain that of the dominant
polymer.
COMPARATIVE EXAMPLE
[0098] A high molecular weight maleated polyethylene such as that
commercially available from Eastman Chemical as Epolene G-2608 is
blended in approximately equal amounts with a common polyethylene
resin. This material retains the strength and flow characteristics
of its constituents, i.e., they fall within the range of what can
normally be found with differing grades of polyethylene. With these
blends, the formulator achieves intermediate levels of acid
functionality sufficient for bonding other polar fibers while
reducing cost. Nonetheless, high temperatures (>180.degree. C.)
and/or pressures (calendering) are still required for bonding to
take place.
EXAMPLE 1 (INVENTION)
[0099] 45% of a high molecular weight maleated polyethylene (such
as that commercially available from Eastman Chemical as Epolene
G-2608) is blended with 55% of a common paraffin (such as that
commercially available as IGI 1230). The resulting blend exhibits
sufficient melt strength for fiber spinning and further bonds
(without pressure) to acrylic at 120.degree. C., which is a
60.degree. C. drop from the temperature required of G-2608 alone.
The mixture does not exhibit blocking on the package even when held
at temperatures above the melting point of the paraffin.
EXAMPLE 2 (INVENTION)
[0100] 50% of a maleated polypropylene wax (such as Eastman's
Epolene C-18) is blended with 50% of a common paraffin (IGI 1230).
This material is coated onto acrylic yarn and incorporated into
chenille yarn. The blend bonds in boiling water baths typical of
dying processes, yet does not exhibit blocking problems upon
shipping. Improved wear resistance of the chenille is achieved at
normal use temperatures in such applications as automotive
upholstery. This example exemplifies a "100.degree. C. flow system"
as discussed herein and is illustrated in FIGS. 1, 3A-B and 4A-C.
In this example, the paraffin component alone exhibits blocking and
no functionality for wet-out. The Epolene wax exhibits too high a
melting point to flow at the desired temperatures. The blend can be
useful as a coating onto a yarn and as a core of a chenille yarn.
The blend can penetrate readily into an effect yarn (such as an
acrylic or cotton effect yarn) at about 100.degree. C. (a
temperature sufficient to drive off water) and can bind it in place
for improved wear resistance. When an additive is blended in the
polymer blend, the blend can be reduced to a powder. The powder can
be sprinkled onto cotton and made to flow at about 100.degree. C.,
creating an extremely thin coating over the cotton and binding the
additive to the cotton.
EXAMPLE 3 (INVENTION)
[0101] A low molecular weight maleated polyethylene or
polypropylene wax, such as those commercially available from
Eastman Chemical under the trade name Epolene, is blended with a
high molecular weight polyethylene or modified polypropylene to
gives results similar to that exhibited by the blend of Example 2.
The blend exhibits high flow yet good fiber-forming properties at
remarkably low temperatures, and at the same time good integrity in
uncontrolled storage conditions. This example exemplifies a
"150.degree. C. flow system" as discussed herein and is illustrated
in FIGS. 2A and 2B. In this example, the polyethylene alone
exhibits poor flow at this temperature and no functionality. The
Epolene wax has too low a viscosity/melt strength to be spun into
fibers. The blend may be useful spun as the sheath of a bicomponent
filaments yarn and the yarn can be used as the core of a chenille
yarn, When heated in an autoclave, the bonder can readily penetrate
into the effect yarn and hold it in place for improved wear
resistance.
EXAMPLE 4 (INVENTION)
[0102] A binder/additive delivery system of the invention can be
provided for delivery of a hard-coat to a sheet product, such as
polyester glazing. Suitable additives useful in this application
include without limitation rigid flake products, such as glass
flake, mica, and the like, and mixtures thereof. Mica flake can be
more economically feasible than glass and further its functionality
can contribute to good wet-out. In this example, a 1:1:1 mixture of
paraffin, maleated polypropylene (PP) wax, and mica flake is
prepared and applied to a sheet product, for example by sprinkling,
spraying, foaming or other suitable techniques. A mild
heat-treatment (steam or hot air gun) allows the blend to uniformly
cover the surface of the product, wet out for optical clarity, and
present the hard mica flake for wear and abrasion resistance.
Abraded surfaces can be repaired/reflowed by additional
heat-treatment, with or without the addition of more of the
mixture. To improve adhesion, the glazing can have polar
functionality to react with the acid in the wax. This can be
accomplished, for example in the case of polyester glazing, by
incorporating a tie layer of a bonding material such as a phenoxy
resin, or by including an additive in the polyester itself, again
such as phenoxy.
EXAMPLE 5 (INVENTION)
[0103] Phenoxy polymer (MW about 20,000) is an amorphous polymer
used as a binder in composite automotive structures such as
headliners. The Tg is about 90.degree. C. and is important to
preventing creep at elevated temperatures of an automotive
interior. The high molecular weight limits its ability to flow and
wet out a fibrous mat. The lack of crystallinity makes it difficult
to spin into a fiber form, since it does not strain-harden.
[0104] When blended with pentaerythritol tetrabenzoate (PETB, sold
as Uniplex 552 by Unitex Chemical Co.), non-polymeric MW=552,
Tm=104.degree. C. at 10-25%, the phenoxy blend flows much more
readily when molded in a headliner, giving superior wet-out. PETB
is an example of a substantially crystalline plasticizer, which in
the invention as discussed herein has a Tm that is greater than the
Tg of the phenoxy. The improved flowability also allows spinning
into a fiber form, either as a filament yarn or as a non-woven, in
part because the melt now increases in modulus more when oriented
(much like solution spinning). Normally one would expect that such
a plasticizer reduces Tg, which it does by as much as 25.degree. C.
However, because the PETB has a crystalline melt point higher than
the Tg of the phenoxy, the mixture in fact shows a cold-flow point
higher than the Tg of the unmodified phenoxy. Thus it continues to
be useful as a binder in elevated temperature environments, does
not creep excessively or become tacky as might be predicted by the
Tg.
[0105] Example 1 of the invention above is similar to Example 5 in
principle. The high molecular weight maleated polyethylene is a
desirable binder, yet will not flow well at temperatures cotton
will survive without discoloring. Adding (crystalline) paraffin
improves flow without making the blend tacky.
EXAMPLE 6 (INVENTION)
[0106] Polypropylene is spun into synthetic fibers using a low
level of polar functional additive, which comes to the surface. The
polar functional additive can be, for example, an ionomer, PVOH, or
the like. The maleic acid functional binders then wet the
polypropylene fiber spontaneously, where previously polypropylene
fiber is difficult to adhere to.
[0107] Various exemplary polymer blends of the invention are
prepared and applied to a fibrous substrate to evaluate the flow
properties thereof. FIGS. 1-4 are photomicrographs illustrating
various behavior characteristics of exemplary polymer blends of the
invention.
[0108] FIG. 1 is a photomicrograph of particles formed of an
exemplary polymer blend of the invention, which blend can have an
activating temperature of about 100.degree. C. (a"100.degree. C.
Flow" system). The photomicrograph illustrates that the polymer
blend material can be friable and treated to form a characteristic
grain size under suitable conditions. The material of FIG. 1, for
example, includes particles of about 50 microns (2 mils) and larger
particles show sharp features and internal cracking with this same
length scale. This indicates that the polymer blend materials of
the invention, such as the illustrated 100.degree. C. flow
material, can be reduced to a substantially stable powder,
including 50 um powder, using suitable treatments as known in the
art.
[0109] FIGS. 2A and 2B are photomicrographs illustrating the
ability of exemplary high flow temperature blends of the invention
to suitably penetrate a fibrous substrate, for example, the strong
thermodynamic drive for the polymer blend (binder) of the invention
to penetrate a cotton fabric. In particular, FIGS. 2A and 2B are
micrographs of a "150.degree. C. Flow" system applied to a cotton
substrate. FIG. 2A is a photomicrograph of the back of a cotton
fabric to which a polymer blend having an activating temperature of
about 150.degree. C. is applied after 11 minutes at 125.degree. C.,
and FIG. 2B is a photomicrograph of a cotton fabric to which a
polymer blend having an activating temperature of about 150.degree.
C. is applied after 50 minutes at 150.degree. C. In this example,
even an unreduced (3 mm) pellet of a polymer blend having an
activating temperature of about 150.degree. C. can flow into a
cotton fabric. The photomicrographs demonstrate that after just 11
minutes at 125.degree. C., the pellets have become droplets and wet
through to the back of the fabric. With higher heat and longer
exposure, the droplets can be absorbed completely. In contrast, the
polymer blend system of FIG. 1 (the "100.degree. C. Flow" system)
would be expected to look like the micrograph of FIG. 2B
substantially as soon as it was brought to temperature. A finer
dispersion of powder would be expected to provide thin, uniform
coverage.
[0110] FIGS. 3A and 3B are photomicrographs illustrating the
loading of roughly ground pellets formed of an exemplary polymer
blend of the invention having an activating temperature of about
100.degree. C. on a cotton fabric. The inserted text gives
dimensions of the largest droplets. Good contact angles are
observed yet large droplets approximating the original size range
of the polymer blend particles as applied to the substrate remain.
Far less mass was found under the microscope, however, than was
added, a phenomenon clarified in FIGS. 4A-C, discussed below.
[0111] FIGS. 4A, 4B and 4C are higher resolution photomicrographs
of the polymer blend of the invention of FIGS. 3A and B as applied
to a cotton substrate and demonstrate polymer droplet wicking
(rather than elongating) down a fiber surface to form thin flexible
coating layers. Following fiber saturation in a given area of the
fabric, wicking ceases and the droplets seen in FIGS. 3A and B
remain at a stable size. However, if the fabric is compressed and
unsaturated fibers come in contact with the droplets (or saturated
fibers) during heat exposure, the flow will continue until the
droplet reservoir is depleted.
[0112] The photomicrographs generally illustrate various behaviors
of exemplary polymer blends in accordance with the present
invention that make such systems useful vehicles for additive
delivery. As non-limiting examples, pellets of the polymer blends
can be reduced down to at least 50 micron particle size, with
smaller additive particles suspended in them. The polymer blends
can be dispersed onto the surface of a fabric by simple slurry or
foaming methods. Once heated to activation temperature, the polymer
blends can melt and flow along the fabric surfaces and through the
fabric interstices, thereby forming thin layers on the surface of
the fibers, and carrying the additive particles with them. These
particles can thereafter be thinly encapsulated and well adhered to
the natural fiber matrix.
[0113] Many modifications and other embodiments of the invention
will come to mind to one skilled in the art to which this invention
pertains having the benefit of the teachings presented in the
foregoing descriptions. Therefore, it is to be understood that the
invention is not to be limited to the specific embodiments
disclosed and that modifications and other embodiments are intended
to be included within the scope of the appended claims. Although
specific terms are employed herein, they are used in a generic and
descriptive sense only and not for purposes of limitation, the
scope of the invention being defined in the claims.
* * * * *