U.S. patent application number 09/903362 was filed with the patent office on 2002-04-04 for thermoplastic superabsorbent polymer blend compositions and their preparation.
Invention is credited to Achille, Felix.
Application Number | 20020039869 09/903362 |
Document ID | / |
Family ID | 22823899 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020039869 |
Kind Code |
A1 |
Achille, Felix |
April 4, 2002 |
Thermoplastic superabsorbent polymer blend compositions and their
preparation
Abstract
An extrudable thermoplastic superabsorbent polymer blend
composition is disclosed. The blend compositions are especially
well suited for preparation of extruded or molded articles such as
monolayer films, multilayer films, nonwoven webs, sheets, foams,
profiles, multilayer laminates, fibers, tubes, rods or pipes which
in turn are well suited for preparation of power and communication
cables or disposable absorbent articles such as diapers, sanitary
napkins, tampons, incontinence products, hospital gowns or bed
pads.
Inventors: |
Achille, Felix; (Midland,
MI) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Family ID: |
22823899 |
Appl. No.: |
09/903362 |
Filed: |
July 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60220529 |
Jul 24, 2000 |
|
|
|
Current U.S.
Class: |
442/417 ;
442/361; 442/394; 442/400; 442/401 |
Current CPC
Class: |
B01J 20/28023 20130101;
Y10T 442/699 20150401; C08J 2300/14 20130101; B01J 20/28033
20130101; Y10T 442/68 20150401; G02B 6/4494 20130101; B01J 20/26
20130101; A61L 15/60 20130101; B01J 2220/44 20130101; Y10T 442/674
20150401; C08J 3/246 20130101; C08L 101/14 20130101; Y10T 442/681
20150401; Y10T 442/637 20150401; A61L 15/48 20130101; A61L 15/225
20130101 |
Class at
Publication: |
442/417 ;
442/361; 442/394; 442/400; 442/401 |
International
Class: |
D04H 001/00; D04H
013/00; D04H 003/16 |
Claims
What is claimed is:
1. An extrudable thermoplastic superabsorbent polymer blend
composition comprising (a) one or more superabsorbent polymer and
(b) one or more thermoplastic resin comprising a functional group
which interacts ionically or covalently with (a).
2. The extrudable thermoplastic superabsorbent polymer blend
composition of claim 1 having a melt draw down rate between about 5
and about 100 feet per minute and a melt tension between about 0.1
and about 10 under temperature and applied load conditions that
give a melt flow rate of between about 0.1 and about 300 g/10
min.
3. The extrudable thermoplastic superabsorbent polymer blend
composition of claim 1 wherein the superabsorbent polymer is
prepared from water-soluble .alpha.,.beta.-ethylenically
unsaturated monomers.
4. The extrudable thermoplastic superabsorbent polymer of claim 3
wherein the .alpha.,.beta.-ethylenically unsaturated monomers is a
monocarboxylic acid, a vinyl polycarboxylic acid, an acrylamide or
mixtures thereof.
5. The extrudable thermoplastic superabsorbent polymer blend
composition of claim 1 wherein the superabsorbent polymer is a
cellulosic-graft copolymer, a starch-graft copolymer, a
starch-g-poly(acrylic acid), a polyacrylamide; a polyvinyl alcohol,
a poly(acrylic acid), a copolymer of sulfonic acid group containing
monomer, or mixtures thereof.
6. The superabsorbent polymer of claim 5 is crosslinked, partially
neutralized, surface treated or combinations thereof.
7. The extrudable thermoplastic superabsorbent polymer blend
composition of claim 1 wherein the thermoplastic resin is a
polyacrylic acid, ethylene and acrylic acid copolymer, ethylene,
t-butylacrylate and acrylic acid terpolymer, ethylene and
methacrylic acid copolymer, ionomers of ethylene and methacrylic
acid copolymers, ethylene, vinyl acetate and carbon monoxide
terpolymer, ethylene and carbon monoxide copolymer, ethylene,
acrylic acid and carbon monoxide terpolymers, ethylene,
n-butylacrylate and carbon monoxide terpolymer or blends
thereof.
8. The extrudable thermoplastic superabsorbent polymer blend
composition of claim 1 further comprising a surfactant.
9. The extrudable thermoplastic superabsorbent polymer blend
composition of claims 1, 3 or 8 further comprising a polyethylene,
a copolymer of polyethylene, a polypropylene, a copolymer of
polypropylene or a polystyrene.
10. A method for preparing an extrudable thermoplastic
superabsorbent polymer blend composition comprising the step of
combining: (a) one or more superabsorbent polymer and (b) one or
more thermoplastic resin comprising a functional group which
interacts ionically or covalently with (a).
11. The method of claim 10 further comprising the step of combining
(c) a surfactant.
12. A method for producing an extruded or molded article of an
extrudable thermoplastic superabsorbent polymer blend composition
comprising the steps of: 1) preparing an extrudable thermoplastic
superabsorbent polymer composition comprising (c) one or more
superabsorbent polymer and (b) one or more thermoplastic resin
comprising a functional group which interacts ionically or
covalently with (a) and 2) extruding or molding said thermoplastic
superabsorbent polymer composition into an extruded or molded
article.
13. The method of claim 12 wherein the superabsorbent polymer
composition further comprising (c) a surfactant.
14. The method of claims 12 or 13 wherein the extruded article is a
monolayer film, a multilayer film, a nonwoven web, a sheet, a foam,
a profile, a multilayer laminate, a fiber, a tube, a rod or a
pipe.
15. The method of claims 12 or 13 wherein the extruded article is a
monofilament fiber, a bicomponent monofilament fiber, a spun bond
nonwoven web, a melt blown nonwoven web, or a composite comprising
combinations thereof.
16. The method of claims 12 or 13 wherein the extruded article is a
nonwoven web comprising a spun bond nonwoven web comprising one or
more bicomponent fiber, a melt blown nonwoven web comprising one or
more bicomponent fiber, or a composite structure comprising at
least one layer of one or more spun bond nonwoven web and at least
one layer of one or more melt blown nonwoven web wherein one or
more layers of the composite comprise bicomponent fibers.
17. The composition of claims 1 or 8 in the form of an extruded or
molded article.
18. The extruded or molded article of claim 17 is a monolayer film,
a multilayer film, a nonwoven web, a sheet, a foam, a profile, a
multilayer laminate, a fiber, a tube, a rod or a pipe.
19. The extruded or molded article of claim 17 is a monofilament
fiber, a bicomponent monofilament fiber, a spun bond nonwoven web,
melt blown nonwoven web, or a composite comprising combinations
thereof.
20. The extruded or molded article of claim 17 is a nonwoven web
comprising a spun bond nonwoven web comprising one or more
bicomponent fiber, a melt blown nonwoven web comprising one or more
bicomponent fiber, or a composite structure comprising at least one
layer of one or more spun bond nonwoven web and at least one layer
of one or more melt blown nonwoven web wherein one or more layers
of the composite comprise bicomponent fibers.
21. The monolayer film or multilayer film of claim 18 laminated to
a metal.
22. A power cable comprising the metal laminate of claim 21.
23. A communications cable comprising the metal laminate of claim
21.
24. A power cable comprising the monolayer film or multilayer film
of claim 18.
25. A communications cable comprising the monolayer film or
multilayer film of claim 18.
26. A disposable absorbent device comprising an extruded or molded
article of claim 18.
27. The disposable absorbent device of claim 26 is a diaper, a
sanitary napkin, a tampon, an incontinence product, a hospital gown
or a bed pad.
28. A disposable absorbent device comprising an extruded or molded
article of claim 19.
29. The disposable absorbent device of claim 28 is a diaper, a
sanitary napkin, a tampon, an incontinence product, a hospital gown
or a bed pad.
30. A disposable absorbent device comprising an extruded or molded
article of claim 20.
31. The disposable absorbent device of claim 30 is a diaper, a
sanitary napkin, a tampon, an incontinence product, a hospital gown
or a bed pad.
Description
CROSS REFERENCE STATEMENT
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/220,529, filed Jul. 24, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates to a thermoplastic polymer
blend composition comprising a superabsorbent polymer and method of
preparation thereof.
BACKGROUND OF THE INVENTION
[0003] Superabsorbent polymers are well-known materials that are
used in a variety of applications ranging from personal care
articles such as diapers to water barrier applications in the
construction industry to water blocking agents in communications
cables to liquid absorbers in food packaging systems. These
polymers are known to absorb several times their weight of, for
example, moisture, water, saline solution, urine, blood, serous
body fluids and the like.
[0004] One of the challenges of using superabsorbent polymer
particles within an absorbent device is the containment or fixation
of the superabsorbent polymer particles. Depending on the
particular absorbent device, different approaches to contain or fix
the superabsorbent polymer particles have been taken. For example,
disposable absorbent products such as diapers, sanitary napkins,
tampons, incontinence products, and the like typically comprise a
matt or batt wrapped with a liner wherein the batt usually
comprises the superabsorbent polymer in particulate form, see U.S.
Pat. No. 3,670,731. However, loss of particles and/or
redistribution of the particles within the device, sometimes
referred to as shakeout, often occurs.
[0005] An attempt to reduce shakeout is taught in U.S. Pat. No.
4,806,598 which discloses nonwoven webs made from a thermoplastic
polymer composition comprising a polyoxyethylene superabsorbent
comprising a soft segment bonded to a hard segment through a
reaction with a third segment and a thermoplastic polymer. However,
there is little interaction between the polyoxyethylene
superabsorbent and the thermoplastic polymer and the blends are not
stable with regard to phase separation. Further, webs made from the
thermoplastic polymer composition do not demonstrate adequate wet
strength and attempts to improve the wet strength of the webs by
replacing some of the thermoplastic polymer composition with a low
density polyethylene results in substantially decreasing the water
absorbency of the web.
[0006] In power and communication cable applications different
approaches have been tried to bind or fix superabsorbent polymers
as water-blocking agents. For examples, see U.S. Pat. No. 4,966,809
which discloses water-blocking tapes made by mixing a
superabsorbent polymer and a polymeric binder and then spreading
the mixture on nonwoven fabrics, see U.S. Pat. No. 5,461,195 which
discloses a superabsorbent polymer mixed with a thixotropic agent
to form a gel which is used to fill the spaces between the wires of
the cable or see U.S. Pat. No. 5,925,461 which discloses
strengthening members or buffer tubes coated or impregnated with a
hot melt adhesive comprising a super absorbent.
[0007] Mixtures of superabsorbent polymers and binders are
characterized by a number of disadvantages and/or limitations, such
as manufacturing and operating temperature limitations, lack of
adhesion to the substrates to which the mixture is applied, and
delaminating when the article is pulled in the tensile direction,
that contribute to abrasion when the article is being fabricated
and the like. Further, tapes add additional components in the
construction of cables causing considerable unwanted increases in
their costs and diameters. Cables using filler gels are
characterized by a number of disadvantages and/or limitations such
as manufacturing and operating temperature limitations, formation
of voids which lead to paths of water migration, and difficulties
meeting industry standards.
[0008] Other methods to bind superabsorbent polymers are known. For
example see, U.S. Pat. No. 5,516,585 which discloses a method of
coating discontinuous fibers with a thermoset binder material which
binds particles of superabsorbent wherein the discontinuous fibers
are formed into a web. In a method described in U.S. Pat. No.
4,392,908 superabsorbent polymer particles are coated with a
thermoplastic resin and fixed to a water-absorbent substrate by
applying heat to soften the thermoplastic coating of the particles
and pressing the particles and substrate to cause the particles to
bind to the substrate. These methods are expensive requiring
specialized equipment and/or many steps and have limited commercial
applicability.
[0009] Further, films and laminates of superabsorbent polymers have
been made from solutions of superabsorbent polymers followed by
heating and/or removing the solvent. For examples of cross-linked
superabsorbent polymer films and laminates see U.S. Pat. Nos.
3,926,891, 4,076,673 and 4,117,184. For examples of
non-cross-linked superabsorbent polymer films see U.S. Pat. Nos.
3,935,099, 3,997,484 and 4,090,013. U.S. Pat. No. 3,669,103
describes a method to make thin foamed polyurethane thermoset sheet
comprising superabsorbent polymer particles. Unfortunately, these
methods of forming films, laminates and sheet are impractical for
large-scale commercial use.
[0010] It would be desirable to have a superabsorbent polymer
composition with improved containment of superabsorbent polymer
particles for use in absorbent devices such as personal-care
articles and cable wrap components while maintaining good
absorptive properties. Further, it would be desirable for such a
superabsorbent polymer composition to be easily and conveniently
shaped into a variety of useful forms, especially on a commercial
scale.
SUMMARY OF THE INVENTION
[0011] The present invention is such a composition. It is a
thermoplastic superabsorbent polymer blend composition comprising
(a) a superabsorbent polymer (b) a thermoplastic resin and
optionally (c) a surfactant wherein components (a) and (b) interact
with each other ionically or covalently and the blend composition
can be formed by extrusion, for example, into film, sheet,
laminates, foams, profiles and injection molded articles.
[0012] In another aspect, the present invention is a process for
preparing the abovementioned extrudable thermoplastic
superabsorbent polymer blend composition.
[0013] In a further aspect, the present invention involves a method
of extruding or molding the abovementioned extrudable thermoplastic
superabsorbent polymer blend composition.
[0014] In yet a further aspect, the invention involves extruded
(e.g., film, sheet, foam, laminates, and the like) or molded
articles of the abovementioned extrudable thermoplastic
superabsorbent polymer blend composition.
[0015] In yet a further aspect, the invention involves articles
comprising extruded or molded articles of the abovementioned
extrudable thermoplastic superabsorbent polymer blend
composition.
[0016] The blend compositions and extruded and molded articles of
the present invention may be employed in a wide variety of uses as
are known in the art, such as, for example, the assembly or
construction of cable wrap components and various disposable
absorbent articles, such as sanitary napkins, disposable diapers,
hospital gowns, bed pads and the like.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The superabsorbent water-swellable or lightly cross-linked
hydrophilic polymers suitably employable in the present invention
can be any of the known hydrophilic polymers that are capable of
absorbing large quantities of fluids. These polymers are well known
in the art and are widely commercially available.
[0018] Examples of some suitable polymers and processes, including
gel polymerization processes, for preparing superabsorbent polymers
are disclosed in U.S. Pat. Nos. 3,997,484; 3,926,891; 3,935,099;
4,090,013; 4,093,776; 4,340,706; 4,446,261; 4,683,274; 4,459,396;
4,708,997; 4,076,663; 4,190,562; 4,286,082; 4,857,610; 4,985,518;
and 5,145,906, which are incorporated herein by reference. In
addition, see Buchholz, F. L. and Graham, A. T., "Modern
Superabsorbent Polymer Technology," John Wiley & Sons (1998)
and Lisa Brannon-Peppas and Ronald S. Harland, "Absorbent Polymer
Technology" Elsevier (1990).
[0019] Preferred superabsorbent polymers are prepared from
water-soluble .alpha.,.beta.-ethylenically unsaturated monomers
such as monocarboxylic acids, vinyl polycarboxylic acids,
acrylamide and their derivatives. More preferred superabsorbent
polymers are cellulosic or starch-graft copolymers, such as
starch-g-poly(acrylonitrile), starch-g-poly(acrylic acid) and the
like; polyacrylamides; polyvinyl alcohols; poly(acrylic acids);
high molecular weight polymers, preferably cross-linked, of
ethyleneoxide (EO) and propyleneoxide (PO); copolymers of sulfonic
acid group containing monomers, such as vinyl sulfonic acid, sodium
sulfoethyl methacrylate, 2-Acrylamido-2-Methylpropane-sulfonic acid
or the sodium salt (AMPS) and the like.
[0020] Most preferred superabsorbent polymers are crosslinked,
partially neutralized and/or surface treated. Preferably, the level
of crosslinking is selected to give the desired swelling
characteristics for the particular application. Generally, the
degree of neutralization is from about 30 to about 100 percent,
more preferably from about 50 to about 80 percent. Neutralization
with a basic substance containing a Group I metal ion, such as
sodium, is preferred. A preferred surface treatment consists of a
post polymerization reaction to effect the surface crosslinking of
the superabsorbent polymer.
[0021] The amount of the superabsorbent polymer to be included in
the thermoplastic superabsorbent polymer blend composition
according to the present invention will vary depending, for
example, upon the type of superabsorbent polymer used, the type of
thermoplastic resin used, the desired extruded or molded product,
the extruded or molded product's end use application, the desired
level of blocking, absorbing or stopping the migration of water
and/or other fluids in the end use application, etc.
[0022] The superabsorbent polymer is present in an amount equal to
or greater than about 1 part per weight, preferably equal to or
greater than about 5 parts per weight, more preferably equal to or
greater than about 10 parts per weight, even more preferably equal
to or greater than about 15 parts per weight and most preferably
equal to or greater than about 20 parts per weight based on the
weight of the thermoplastic superabsorbent polymer blend
composition. The amount of superabsorbent polymer is present in an
amount equal to or less than about 70 part per weight, preferably
equal to or less than about 65 parts per weight, more preferably
equal to or less than about 60 parts per weight, even more
preferably equal to or less than about 55 parts per weight and most
preferably equal to or less than about 50 parts per weight based on
the weight of the thermoplastic superabsorbent polymer blend
composition.
[0023] In addition to a superabsorbent polymer, the blend
composition of the present invention contains at least one
thermoplastic resin that interacts (i.e., ionically, covalently,
etc.) with the superabsorbent polymer. For example, a thermoplastic
resin having an acyl groups which can undergo nucleophilic attack
resulting in a substitution reaction in which a leaving group, such
as --OH, --Cl, --OOCR, --NH2 or --OR, is replaced by another basic
group present in the superabsorbent polymer. Another example is a
thermoplastic resin containing carbonyl groups that can undergo a
nucleophilic attack gaining a proton and adding another basic group
present in the superabsorbent polymer. Under these conditions the
reaction product of the thermoplastic resin and superabsorbent
polymer may form a uniform and/or co-continuous non-separating
polymer blend.
[0024] Preferred thermoplastic resins have functional groups such
as acyl or carbonyl groups (e.g., .alpha.,.beta.-unsaturated
carbonyl compounds, hydroxy acids, dicarboxylic acids, keto acids,
anhydrides, carboxylic acids, aldehydes, ketones, acid halides,
esters, amides, etc.), sulfonyls, sulfonyls halides, ethers,
phenols, aryl halides, epoxides, carbohydrates, alcohols, azides,
amines and the like.
[0025] The preferred thermoplastic resins are acrylic polymers,
with polyacrylic acid (PAA), ethylene and acrylic acid copolymers
(EAA), ethylene, t-butylacrylate and acrylic acid terpolymer
(EtBAAA), ethylene and methacrylic acid copolymers (EMAA), ionomers
of ethylene and methacrylic acid copolymers especially the sodium
and zinc ionomers, ethylene, vinyl acetate and carbon monoxide
terpolymers (EVACO), ethylene and carbon monoxide copolymers (ECO),
ethylene, acrylic acid and carbon monoxide terpolymers (EAACO),
ethylene, n-butylacrylate and carbon monoxide terpolymers (EnBACO)
and blends thereof being most preferred.
[0026] The most preferred thermoplastic resins are 1) an EAA
copolymer, wherein the EAA copolymer may be a blend of two or more
EAA copolymers, preferably having a composition from about 10 to
about 20 weight percent acrylic acid based on the weight of the
copolymer and a melt flow rate (MFR) from about 100 to about 200
grams per 10 minutes (g/10 min.) under conditions of 190.degree. C.
and an applied load of 2.16 kg., 2) ionomers of EMAA, preferably
the zinc ionomer, 3) EVACO, preferably having a carbon monoxide
content of at least 9 percent based on the weight of the terpolymer
or 4) blends thereof.
[0027] The thermoplastic resin is present in an amount equal to or
greater than about 30 part per weight, preferably equal to or
greater than about 35 parts per weight, more preferably equal to or
greater than about 40 parts per weight, even more preferably equal
to or greater than about 45 parts per weight and most preferably
equal to or greater than about 50 parts per weight based on the
weight of the thermoplastic superabsorbent polymer blend
composition. The amount of thermoplastic resin is present in an
amount equal to or less than about 99 parts per weight, preferably
equal to or less than about 95 parts per weight, more preferably
equal to or less than about 90 parts per weight, even more
preferably equal to or less than about 85 parts per weight and most
preferably equal to or less than about 80 parts per weight based on
the weight of the thermoplastic superabsorbent polymer blend
composition.
[0028] It should be apparent to those having ordinary skill in the
art that the present invention contemplates blends containing two
or more superabsorbent polymers and/or blends of two or more
thermoplastic resins (e.g., EAA/EVACO, EMAA/EAA, a first EAA/a
second EAA and the like).
[0029] While the blend compositions of the present invention
contain at least one superabsorbent polymer, such blend
compositions may or may not be superabsorbent, depending upon the
level and absorbency of the superabsorbent polymer in the blend
composition and the availability of the superabsorbent polymer to
aqueous media.
[0030] The blend compositions of the present invention can be
further blended with other thermoplastic polymers, preferably low
density polyethylene (LDPE), linear low density polyethylene
(LLDPE), very low density polyethylene (VLDPE), polypropylene (PP),
polystyrene (PS), ethylene and methylacrylate copolymer (EMA),
ethylene and ethylacrylate copolymer (EEA), ethylene and
n-butylacrylate copolymer (EnBA), polyethylene grafted with maleic
anhydride grafted (PE g-MAH), ethylene and vinyl acetate copolymer
(EVA), ethylene and vinyl acetate copolymer grafted with maleic
anhydride grafted (EVA g-MAH), or combinations thereof.
[0031] The blend compositions of the present invention may further
comprise additional additives commonly used in compositions of this
type such as lubricants, extenders, compatibilizers, plasticizers,
low and high molecular weight waxes, surfactants, stabilizers,
pigments, carbon black and fillers such as talc, titanium dioxide
(TiO.sub.2), calcium carbonate (CaCO.sub.3), magnesium oxide (MgO),
mica and the like.
[0032] The blend compositions of the present invention may further
be blended with a solvent to form a dispersion or paste. One
skilled in the art can readily choose the type and amount of
solvent depending on the particular end use.
[0033] As used herein, the phrase "extrudable thermoplastic
superabsorbent polymer blend composition" means that: (1) the blend
composition is melt processable in an extrusion, injection molding
and/or blow molding process, (2) the extrudate is either commuted
to pellets or directly extruded or molded by extrusion fabrication
technique, (3) the pellets have a measurable melt flow rate, melt
draw rate and melt strength sometimes referred to as melt tension
and (4) the pellets can be re-extruded by an extrusion fabrication
techniques. Preferably, the blend compositions of the present
invention do not cause plugging, die-face build up, surging, melt
fracture, pinholes, tearing and/or poor extrudate properties (i.e.,
strand dropping, delamination, etc.) during the extrusion
process.
[0034] A melt indexer is used to determine melt flow rate (MFR),
melt tension and draw down rate. MFR is determined by ASTM D 1238;
the run conditions (i.e., temperature and applied load) depend upon
the thermoplastic resin used. Melt tension is determined from a
load cell attached at the bottom of the melt indexer which measures
the load required to pull the extrudate from the die of the melt
indexer to a take up reel at some given speed measured in feet per
minute (fpm). The draw down rate (fpm) is determined by how fast
the extrudate coming out of the melt indexer can be pulled before
it breaks. When MFR conditions are selected to give a MFR between
about 0.1 and about 300 g/10 min. the thermoplastic superabsorbent
polymer blend composition has a melt draw down rate between about 5
and about 100 fpm and a melt tension between about 0.1 and about
10.
[0035] The components of the extruded blend composition can be
co-continuous or separate phases (one being continuous and one or
more being dispersed therein) as long as phase separation does not
have a significant deleterious effect on the melt processability or
performance of the blend composition.
[0036] Preferred extrusion fabrication techniques include preparing
melt blown or cast films; extrusion coating; (co)extruding nonwoven
webs, including spun bond nonwoven webs, melt blown nonwoven webs,
or composites comprising combinations thereof, sheets, foams,
profiles, multilayer laminates, fibers including monofilament
fibers and bicomponent monofilament fibers, tubes, rods or pipes;
blow molding articles; injection molding articles (including solid,
co-injection, structural foam and gas assist injection molding).
Preferred nonwoven webs comprise spun bond nonwoven webs comprising
one or more bicomponent fiber, melt blown nonwoven webs comprising
one or more bicomponent fiber, and a composite structure comprising
at least one layer of one or more spun bond nonwoven web and at
least one layer of one or more melt blown nonwoven web wherein one
or more layers of the composite comprise bicomponent fibers.
[0037] The thermoplastic superabsorbent polymer blend compositions
of the present invention can be extruded into foam using a chemical
or physical blowing agent. Further, the thermoplastic
superabsorbent polymer can be blended with other miscible or
compatible thermoplastic polymers such as LDPE, LLDPE, VLDPE, PP,
PS, EEA, EMA, ENBA, PE g-MAH, EVA, EVA g-MAH or the like. One
skilled in the art can choose the type and amount of blowing agent
as well as other polymers to blend with the thermoplastic
superabsorbent polymer for the particular end use in order to
modify the cell size, structure, porosity, microcellular nature and
absorbency characteristics of the thermoplastic superabsorbent
polymer foam as desired.
[0038] The blend compositions to make foam may further comprise
additional additives commonly used in compositions of this type
such as lubricants, extenders, nucleators, compatibilizers,
plasticizers, low and high molecular weight waxes, surfactants,
stabilizers, pigments, carbon black and fillers such as talc,
TiO.sub.2, CaCO.sub.3, MgO, mica and the like.
[0039] Further, extruded pellets or sheet can be compression
molded; calendered; vacuum formed or thermoformed. Preparation of
the thermoplastic superabsorbent polymer blend compositions of this
invention can be accomplished by any suitable mixing means known in
the art. Typically the components and any additional additives are
blended in a tumbler or shaker in powder, particulate and/or pellet
form with sufficient agitation to obtain thorough distribution
thereof. The dry-blended formulation can further be subjected to
shearing stresses at a temperature sufficient to heat soften and
melt-mix the polymers, for example in an extruder, with or without
a vacuum, or other mixing apparatuses (e.g., a Banbury mixer,
roller mill, Henschel mixer, a ribbon blender, etc.). Further,
additional powder, particulate and/or liquid additives may be added
to the composition during the mixing process. Such melt-mixed
material can be extruded to make the finished article (i.e., film,
sheet, foam, profile, etc.) or recovered in the form of a pellet,
powder or flake, preferably a pellet. The extrudate may be commuted
to pellets by any conventional means such as a strand chopper or an
underwater die face cutter.
[0040] The extrudate from the melt-mixing may be cooled by any
method known in the art, such as air cooled, gas cooled, belt
cooled, liquid cooled by passing through a liquid bath, and the
like. Preferably a stainless steel belt cooler, for example
manufactured by Sandvik Process Systems, Sweden or a Compact Conti
Cooler manufactured by BBA AG, Switzerland, or an aqueous liquid
bath, preferably where the pH is less than 1.0 or an aqueous liquid
bath with a water hardness of greater than 25 French Degrees, more
preferably an aqueous liquid bath with a specific gravity greater
than about 1.05 as measured with a desitometer is used. The aqueous
bath preferably contains a saturated salt solution containing a
Group 1 metal ion, preferably sodium, such as sodium chloride
(NaCl), sodium sulfate (Na.sub.2SO.sub.4), sodium bicarbonate
(NaHCO.sub.3) and the like.
[0041] Further, to minimize the effect of the water on the
superabsorbent compound it has been discovered that maintaining the
temperature of the liquid bath less than about 23.degree. C. and
preferably less than about 20.degree. C. effectively cools the
pellets without grossly activating the superabsorbent polymer in
the blend composition.
[0042] It has farther been found that when using an underwater
pelletizer, optimizing the transfer pipe length from the underwater
pelletizer to the separating dryer minimizes the activation of the
superabsorbent polymer in the blend composition.
[0043] Blowing cool air in the pellet-collecting vessel, such as
the use of a fluidized bed cooler, to drive away the remaining
moisture on the pellets further improves the drying process.
[0044] It has been found using a process comprising an underwater
die face cutter, a saturated NaHCO.sub.3 solution having a specific
gravity greater than about 1.05 and a temperature less than
20.degree. C. and blowing cool air in the pellet-collecting vessel
yields an extrudable thermoplastic superabsorbent polymer blend
composition in a free flowing plastic pellet form having a moisture
content ranging from 0.2 to 4 weight percent depending on the
superabsorbent polymer, concentration of superabsorbent polymer in
the blend composition and the base thermoplastic resin, wherein
moisture weight percent is based on the weight of the blend
composition.
[0045] The melt-mixed material (powder, flake or pellet) can be
re-extruded or molded to make the finished article. Dry blends of
the blend compositions can also be directly injection molded or
metered into another melt fabrication process without
pre-melt-mixing.
[0046] The extrudable thermoplastic superabsorbent polymer blend
compositions of the present invention are useful in the pellet,
flake or powder form for use in cat litter, solidified
gases/fluids, gelled ice, soil conditioner, frost control,
agricultural delivery systems, gelled biohazards, spill control,
for the fabrication of articles such as foams, such as closed,
semi-porous or microcellular or open cell, bicomponent fibers and
waterproof or waterblocking coating systems, thick film or sheet
for such applications as disposable absorbent articles, such as
sanitary napkins, disposable diapers, hospital gowns, bed pads and
the like, films for such applications as moisture sensitive
systems, moisture, such as water, absorbing structures, for example
in packaging, transportation, construction applications and the
like, diaper backing, meat trays, carpet backing or power and
communication cable water-blocking tapes, film for laminate
structures such as laminated foam structures, laminated non-woven
structures, film for laminates for such applications as cable
shielding tapes for use in power cables or communication cables,
such as fiber optical cables, copper pair cables, coaxial cables
and the like as disclosed in U.S. Pat. Nos. 3,795,540, 4,449,014,
4,731,504 and 4,322,574, which are incorporated herein by
reference.
[0047] It is further desirable that when the present invention is
used in the construction of cables for example, power cables and
communication cables, such as fiber optical cables, copper pair
cables, coaxial cables and the like, the cables meet certain
requirements of water penetration. Most desirably, a cable
structure comprising an extrudable thermoplastic superabsorbent
polymer blend composition resists penetration, sometimes referred
to as water blocking, of water through the cable in the
longitudinal direction.
[0048] To illustrate the practice of this invention, examples are
set forth below.
EXAMPLES
Thermoplastic Superabsorbent Polymer Blend Compositions
[0049] In Comparative Examples A to ZZ and Examples 1 to 13
different thermoplastic resins are melt blended in a Brabender
Plasticoder with CABLOC.TM. 850-13 a sodium polyacrylate
superabsorbent polymer that is surface cross-linked having a
particle size distribution of about 1 to about 300 micrometers
available as a powder from Stockhausen and supplied by the Stewart
Superabsorbents LLC. Unless otherwise noted, the ratio of
superabsorbent polymer to thermoplastic resin is 40:60. The
Brabender Plasticoder conditions are: Barrel temperature ranging
from 275 to 420.degree. F. depending on the thermoplastic resin
being used; Mixing revolutions per minute (RPM) are 80; and Mixing
times range from 1.5 to 2 minutes. A melt indexer is used to
determine the melt flow rate, melt tension and melt draw down rate
of the polymer blends
[0050] Table 1 lists the compositions for Comparative Examples A to
ZZ and Examples 1 to 13 and their properties. In Table 1 blend
compositions which can be melt blended in some fashion and pressed
into a shape or molded into a sheet or an article, but do not meet
the criteria set forth herein as extrudable are designated not
extrudable.
[0051] Comparative Examples AB to AN and Examples 14 to 17 are
compounded on a WP ZK30 twin screw extruder. The SAP and the
polymer are fed separately into the feed section of the extruder,
the vent port of the extruder is open to the atmosphere and the
extrudate is air-cooled.
[0052] The compositions of Comparative Examples AB to AN and
Examples 14 to 17 and extruder temperatures are given in Table 2,
the superabsorbent polymer is present in parts by weight based on
the weight of the thermoplastic superabsorbent polymer blend
composition. In Table 2 compositions that demonstrate die face
build-up and/or plugging are designated "not" extrudable.
1 TABLE 1 Thermoplastic Superabsorbent Polymer Blend Composition
MFR, Melt Draw Exam- Com. Thermoplastic Resin MFR, g/10 Tension,
Rate, Extrud- ple Ex. Grade Supplier Type Condition min units fpm
able A ALATHON .TM. M6060 Equistar HDPE E 5.20 No B LDPE 4005 Dow
Chemical Co. LDPE E 1.98 No C LDPE 4012 Dow Chemical Co. LDPE E 4.5
0.8 <5 No D LDPE 681 Dow Chemical Co. LDPE E 0.72 No E DOWLEX
.TM. 2247A Dow Chemical Co. LLDPE E 1.33 No F ASPUN .TM. 6821 Dow
Chemical Co. LLDPE B 11.2 No G ATTANE .TM. 4201 Dow Chemical Co.
VLDPE E 0.417 No H ATTANE 4402 Dow Chemical Co. VLDPE E 1.16 No I
AFINITY .TM. 1880 Dow Chemical Co. INSITE .TM. PE E 0.594 No J
ENGAGE .TM. 8200 DuPont Dow INSITE PE E 3.26 No K PP 861 Montell PP
L 7.6 No L PS 680 Dow Chemical Co. PS G 5.8 No M Chevron 2252-T
Chevron EMA E 0.42 No N Chevron 2255 Chevron EMA E 1.30 No O
Chevron 1802 Chevron EnBA E 0.44 No P ENGAGE SM8400 Dow Chemical
Co. PE g-MAH/high MAH E 0.28 No Q FUSABOND .TM. 190D DuPont EVA
g-MAH/high MAH E 0.5 No R FUSABOND 197D DuPont EVA g-MAH/high MAH E
0.1 No S FUSABOND 226D DuPont LLDPE g-MAH/high MAH E 0.1 No T
FUSABOND 274D DuPont EPDM g-MAH/medium MAH E 0.1 No U FUSABOND 413D
DuPont PE g-MAH MAH E No V FUSABOND 423G DuPont EA terpolymer
g-MAH/high MAH E 1.43 No W FUSABOND 353D DuPont PP g-MAH/very high
MAH 160.degree. C./ 2.62 No 0.353 Kg X BYNEL .TM. E418 DuPont
Anhydride Modified EVA E 2.41 No Y CXA 3101 DuPont Acid/Acrylate
Modified EVA E 1.71 No Z CXA 4105 DuPont Anhydride Modified LLDPE E
0.84 No AA BYNEL 50E561 DuPont Anhydride Modified PP E 0.90 No BB
BYNEL 2174 DuPont Anhydride Modified EA E 0.75 No CC PLEXAR .TM. 3
Equistar Anhydride Modified EVA E 1.24 No DD PLEXAR 206 Equistar
Anhydride Modified HDPE E 2.77 No EE STEREON .TM. 841A Firestone
SBS block copolymer G 5.42 No FF VECTOR .TM. 4211 Dexco Polymers
SIS block copolymer G 11.58 No GG VECTOR 4461 Dexco Polymers SBS
block copolymer G 9.72 No HH KRATON .TM. G1657 Shell SEBS block
copolymer G 3.82 No II KRATON FG1901X Shell SEBS block copolymer G
0.25 No JJ VECTOR 4411 Dexco Polymers SIS block copolymer G 18.2 No
KK Phillips DK-11 Phillips SBS block copolymer G 3.62 No LL
Phillips K-10 Phillips SBS block copolymer G 4.6 No MM VECTOR 8508
Dexco Polymers SBS block copolymer G 3.1 No NN ESI DE 200 Dow
Chemical Co. Ethylene-Styrene Interpolymer G 4.75 No OO ESI DS 201
Dow Chemical Co. Ethylene-Styrene Interpolymer G 5.6 No PP ELVAX
.TM. 3180 DuPont EVA, 28% VA E 13.68 No QQ ELVAX VOW DuPont EVA,
49% VA B 1.5 No RR GRILTEX .TM. 9 EMS Am. Grilon, Inc CoPolyester
hot melt adhesive C 4.4 No SS GRILTEX D EMS Am. Grilon, Inc
CoPolyester hot melt adhesive C 2.3 No 1519EGF TT MACROMELT .TM.
Henkel Polyamide Resin C No 6238 UU MACROMELT 6206 Henkel Polyamide
Resin C 24.52 No VV PHAE Dow Chemical Co. Thermoplastic Phenoxy
Resin E 7.5 No WW LDPE 457 Dow Chemical Co. ECO, 1% CO E 0.33 No 1
ELVALOY .TM. HP441 DuPont EnBACO E 3.1 1.5 5 Yes 2 ELVALOY EP4924
DuPont EVACO E 7.28 0.5 20 Yes 3 A702 Chevron EEA E 2.8 1.0 5 Yes
XX PRIMACOR .TM. 3330 Dow Chemical Co. EAA, 6.5% AA E 2.2 No 4
PRIMACOR 1410 Dow Chemical Co. EAA, 9.7% AA E 0.72 Yes 5 PRIMACOR
1430 Dow Chemical Co. EAA,; 9.7% AA E 2.43 1.0 5 Yes 6 PRIMACOR
3460 Dow Chemical Co. EAA, 9.7% AA E 8.98 0.6 20 Yes 7 XUS70751.17
Dow Chemical Co. EAA, 20.5% AA B 0.84 1.5 10 Yes YY PRIMACOR 5980
Dow Chemical Co. EAA, 20.5% AA B 0.3 No 8 PRIMACOR blend (a) Dow
Chemical Co. EAA, 15.1% AA B 1.16 1.4 10 Yes 9 ESCOR .TM. ATX 325
Exxon EMAAA E 8.72 0.2 5 Yes 10 NUCREL .TM. 699 DuPont EMAA B 4.6
0.5 5 Yes 11 SURLYN .TM. 8660 DuPont Na-EMAA Ionomer 125.degree.
C./ 1.46 2.0 5 Yes 5.0 Kg 12 SURLYN 1702 DuPont Zn-EMAA Ionomer E
6.0 0.9 45 Yes 13 SURLYN 1702 (b) DuPont Zn-EMAA Ionomer E 4.13 0.5
20 Yes ZZ SURLYN 1702 (c) DuPont Zn-EMAA Ionomer E 2.58 No (a) a
50/50 blend of PRIMACOR 3460 and PRIMACOR 5980 (b) a 50/50 blend of
SURLYN 1702 and CABLOC 850-13 (c) a 40/60 blend of SURLYN 1702 and
CABLOC 850-13 LDPE = low density polyethylene LLDPE = linear low
density polyethylene VLDPE = very low density polyethylene PP =
polypropylene PS = polystyrene EMA = ethylene and methylacrylate
copolymer EnBA = ethylene and n-butylacrylate copolymer PE =
polyethylene g-MAH = grafted with maleic anhydride EVA = ethylene
and vinyl acetate copolymer EPDM = ethylene propylene diene monomer
EA = ethylene and acrylate copolymer SBS = styrene, butadiene and
styrene block copolymer SIS = styrene, isoprene and styrene block
copolymer SEBS = styrene, ethylene, butylene and styrene block
terpolymer ESI = ethylene and styrene interpolymer block copolymer
ECO = ethylene and carbon monoxide copolymer EnBACO = ethylene,
n-butylacrylate and carbon monoxide terpolymer EVACO = ethylene,
vinyl acetate and carbon monoxide terpolymer EEA = ethylene and
ethyl acrylate copolymer EAA = ethylene and acrylic acid copolymer
AA = acrylic acid EMAA = ethylene and methacrylic acid copolymer
EMAAA = ethylene and methyl acrylate and acrylic acid copolymer Na
= sodium Zn = zinc Condition B = 125.degree. C./2.16 kg Condition C
= 150.degree. C./2.16 kg Condition E = 190.degree. C./2.16 kg
Condition G = 200.degree. C./5.0 kg Condition L = 230.degree.
C./2.16 kg
[0053]
2 TABLE 2 Blend Compo- Extruder Exam- Com. Thermoplastic Resin
Superabsorbent sition, parts Temperatures ple Ex. Grade Supplier
Type Polymer Resin SAP .degree. F. Extrudable AB LDPE 681 Dow
Chemical Co. LDPE SAP-1 80 20 310-330 No AC LDPE 681 Dow Chemical
Co. LDPE SAP-1 75 25 310-330 No AD LDPE 681 Dow Chemical Co. LDPE
SAP-1 65 35 310-330 No AE LDPE 681 Dow Chemical Co. LDPE SAP-1 60
40 310-330 No AF ATTANE 4201 Dow Chemical Co. VLDPE SAP-2 80 20
335-370 No AG ATTANE 4203 Dow Chemical Co. VLDPE SAP-1 73 27
321-350 No AH ALATHON 6030 HPPE Equistar HDPE SAP-2 80 20 335-370
No AI DOWLEX 2045 Dow Chemical Co. LLDPE SAP-2 75 25 400-420 No AJ
ELVAX 3180 DuPont EVA, 28% VA SAP-1 60 40 250-260 No AK Aqua Calk
(a) Sumitomo Seika Polyethylene Oxide(a) SAP-1 60 40 250-260 No
Chemical Co., Ltd. AL PRIMACOR 3330 Dow Chemical Co. EAA, 6.5% AA
SAP-1 60 40 310-330 No 14 PRIMACOR 3460 Dow Chemical Co. EAA, 9.7%
AA SAP-1 60 40 250-260 Yes AM PRIMACOR 5980 Dow Chemical Co. EAA,
20.5% AA SAP-1 60 40 250-260 No 15 PRIMACOR blend (b) Dow Chemical
Co. EAA, 15% AA SAP-2 60 40 250-260 Yes AN PRIMACOR blend (b) Dow
Chemical Co. EAA, 15% AA SAP-2 50 50 250-260 No 16 PRIMACOR 3460
Dow Chemical Co. EAA, 6.5% AA SAP-3 60 40 250-260 Yes 17 ELVALOY
EP4924 DuPont EVACO SAP-4 60 40 250-260 Yes (a) Aqua Calk is a
thermoplastic, non-ionic, water-absorbent polymer, manufactured by
cross-linking polyethylene oxide (b) 50:50 blend of PRIMACOR 3460
and PRIMACOR 5980 SAP = superabsorbent polymer SAP-1 is a
polyacrylate based superabsorbent polymer available as CABLOC 1181
from Stockhausen having a particle size distribution from about 1
to about 50 micrometers SAP-2 is a polyacrylate based
superabsorbent polymer available as CABLOC 80HS from Stockhausen
having a particle size distribution from about 1 to about 100
micrometers SAP-3 is a polyacrylate based superabsorbent polymer
available as DRYTECH 2035 from Dow Chemical Company having a
particle size distribution from about 1 to about 500 micrometers
SAP-4 is a polyacrylate based superabsorbent polymer available as
CABLOC 88HS from Stockhausen having a particle size distribution
from about 1 to about 150
[0054] Comparative Examples AO to AW are different neat
thermoplastic resins, Comparative Example AU is neat superabsorbent
polymer CABLOC 850-13, AV is the neat superabsorbent polymer CABLOC
80HS, AW is the neat superabsorbent polymer CABLOC 88HS and
Examples 18 to 30 are different thermoplastic resins compounded
with a superabsorbent polymer. A ZSK 58 millimeter (mm) co-rotating
bi-lobe twin screw extruder having a low shear mixing screw and 10
temperature zones is used. The superabsorbent polymer is fed using
a side port powder screw feeder between zones 4 and 5. Mixing
occurs in zone 6. The transition point between zone 8 and 9 is the
vent port. There is a kneading mixing section prior to the vent
port. The temperature range for the first 3 zones is from 65 to
120.degree. F., for zones 4 and 5 it is from 240 to 255.degree. F.,
for zones 6 to 8 it is from 320 to 335.degree. F. and for zones 9
and 10 it is from 270 to 330.degree. F. The melt temperature is
maintained at 310.degree. F.
[0055] The blend compositions are extruded through a 24 hole
underwater die having hole diameters of 0.110 inch into a liquid
bath containing a NaHCO.sub.3 solution having a specific gravity of
greater than 1.05 as measured with a desitometer with a temperature
maintained below 20.degree. C. A Gala underwater pelletizer with 3
cutting blades is used to pelletize the extrudate. The distance
from the underwater pelletizer to the separating dryer is optimized
to minimize the adsorption of water. Further, cool air is blown on
the pellets in the pellet-collecting vessel driving away any
remaining moisture on the pellets.
[0056] The absorption capacity in pure water (WAC) of the neat
thermoplastic resins Comparative Examples AO to AT, the neat
superabsorbent polymers Comparative Examples AU to AW and the
thermoplastic superabsorbent polymer blend compositions Examples 18
to 30 is measured according to the following procedure: For the
thermoplastic superabsorbent polymer blend compositions a sample
determined to contain 1 gram of the superabsorbent polymer (based
on the percent superabsorbent polymer in the blend composition)
weighing W.sub.1 is placed in 1.5 liter of distilled water and is
shaken on a shaker for 2 hours. The water is filtered from the
swollen particles through a 75 micrometer sieve. The weight of the
swollen particles (W.sub.2) is then measured. The amount of water
absorbed, W.sub.a, is W.sub.2-W.sub.1. For the neat resins and neat
superabsorbent polymers a sample weighing 1 gram is subjected to
the same procedure described herein above.
[0057] The compositions and water absorbed for Comparative Examples
AO to AW and Examples 18 to 30 are shown in Table 3, the
superabsorbent polymer is present in parts by weight based on the
weight of the thermoplastic superabsorbent polymer blend
composition and water absorption is reported as grams of distilled
water absorbed per gram of superabsorbent polymer.
3TABLE 3 CABLOC CABLOC CABLOC Example Com. Ex. Thermoplastic Resin
850-13, parts 8OHS, parts 88HS, parts Water Absorption, g AO SURLYN
1702 0 18 SURLYN 1702 35 3 19 SURLYN 1702 45 212 20 PRIMACOR blend
(a) 40 214 21 ELVALOY EP4924 40 231 22 PRIMACOR 3460 40 239 23
SURLYN 1702 20 2 24 PRIMACOR blend (a) 20 1 25 PRIMACOR blend (a)
30 2 AP PRIMACOR blend (a) 0 26 PRIMACOR blend (b) 40 126 AQ
ELVALOY EP4924 0 27 ELVALOY EP4924 20 2 28 PRIMACOR 3460 40 118 AR
XUS60751.17 0 29 SURLYN 1702 35 1 AS PRIMACOR 1430 0 30 SURLYN 1702
45 96 AT PRIMACOR 5980 0 AU 100 172 AV 100 198 AW 100 153 (a) 50:50
blend of PRIMACOR 3460/PRIMACOR 5980 (b) 50:50 blend of PRIMACOR
1430 and XUS 60751.17 (EAA with 20.5% PAA)
Thermoplastic Superabsorbent Polymer Blended with Polyethylene
[0058] In Examples 31 to 38 thermoplastic superabsorbent polymer is
melt blended in a Brabender Plasticoder with a 70:30 LLDPE:LDPE
polymer blend. The thermoplastic superabsorbent polymer comprises
40 weight percent CABLOC T5066-F which is a sodium polyacrylate
superabsorbent polymer that is surface cross-linked having a
particle size distribution of about 1 to about 60 micrometers
available as a powder from Stockhausen and supplied by the Stewart
Superabsorbents LLC and 60 weight percent of a 50:50 PRIMACOR
5980:PRIMACOR 3460 polymer blend. The Brabender Plasticoder
conditions are: Barrel temperature is set at 275.degree. F.; Mixing
RPM is 80; and Mixing times range from 1.5 to 2 minutes. A melt
indexer is used to determine the melt flow rate, melt tension and
melt draw down rate of the polymer blends. The blend compositions
are considered extrudable. The compositions of Examples 31 to 38
and their MFR, melt tension and draw rates are given in Table
4.
4TABLE 4 LLDPE:LDPE Blend Thermoplastic Resin: polymer blend Ratio
MFR, MFR, Melt Tension, Draw Rate, Example Superabsorbent Polymer
"A" "B" A:B Condition g/10 min units fpm Extrudable 31 60:40 70:30
90:10 C 3.51 0.7 50 Yes PRIMACOR BLEND:CABLOC T5066F LLDPE:LDPE 32
60:40 70:30 80:20 C 4.43 0.8 48 Yes PRIMACOR BLEND:CABLOC T5066F
LLDPE:LDPE 33 60:40 70:30 60:40 C 6.01 0.9 48 Yes PRIMACOR
BLEND:CABLOC T5066F LLDPE:LDPE 34 60:40 70:30 20:80 C 6.17 1.0 34
Yes PRIMACOR BLEND:CABLOC T5066F LLDPE:LDPE 35 60:40 70:30 90:10 E
24.7 0.5 100 Yes PRIMACOR BLEND:CABLOC T5066F LLDPE:LDPE 36 60:40
70:30 80:20 E 25.7 0.6 100 Yes PRIMACOR BLEND:CABLOC T5066F
LLDPE:LDPE 37 60:40 70:30 60:40 E 28.1 0.7 100 Yes PRIMACOR
BLEND:CABLOC T5066F LLDPE:LDPE 38 60:40 70:30 20:80 E 21.9 0.8 100
Yes PRIMACOR BLEND:CABLOC T5066F LLDPE:LDPE PRIMACOR BLEND: 50:50
blend of PRIMACOR 3460/PRIMACOR 5980 LLDPE = linear low density
polyethylene LDPE = low density polyethylene Condition C =
150.degree. C./2.16 kg Condition E = 190.degree. C./2.16 kg
Monolayer Films
[0059] Examples 39 to 42 are monolayer films of thermoplastic
superabsorbent polymer blend compositions produced using a cast
line process. The thermoplastic superabsorbent polymer blend
compositions comprise a thermoplastic resin and CABLOC 850-13. The
temperature zones for the cast film process range from 250.degree.
F. to 320.degree. F. The feedblock and die temperatures range from
270.degree. F. to 320.degree. F. Smooth to textured uniformed film
having a thickness greater than 6.0 mils or web film having a
thickness less than 6.0 mils can be made depending on the take up
speed.
[0060] The compositions and properties of monolayer films Examples
39 to 42 are shown in Table 5, the superabsorbent polymer is
present in parts by weight based on the weight of the thermoplastic
superabsorbent polymer blend composition. Absorption capacity in
pure water was determined by as described hereinabove.
5TABLE 5 CABLOC Example Thermoplastic Resin 850-13, parts Water
Absorption, g 39 SURLYN 1702 35 25 40 SURLYN 1702 45 226 41
PRIMACOR blend (a) 40 219 42 ELVALOY EP4924 40 238 (a) 50:50 blend
of PRIMACOR 3460/PRIMACOR 5980
Monolayer Films Containing Surfactant
[0061] Examples 43 to 46 are mono layer films containing a
surfactant. The thermoplastic superabsorbent polymer is melt
blended in a Brabender Plasticoder with a commercially available
polyethylene containing surfactant compound. The polyethylene
containing surfactant is available from AMPACET as ANTIFOG PE MB
and contains 10 weight percent active surfactant, mono- and di-
glycerides, in a LLDPE/LDPE base polymer. The thermoplastic
superabsorbent polymer comprises 40 weight percent CABLOC T5066-F a
sodium polyacrylate superabsorbent polymer that is surface
cross-linked having a particle size distribution of about 1 to
about 60 micrometers available as a powder from Stockhausen and
supplied by the Stewart Superabsorbents LLC and 60 weight percent
of a 50:50 PRIMACOR 5980:PRIMACOR 3460 polymer blend. The Brabender
Plasticoder conditions are: Barrel temperature is set at
275.degree. F.; Mixing RPM is 80; and Mixing times range from 1.5
to 2 minutes. Water absorption and rate of absorption is measured
by placing a 2 inch disc sample of a 5 to 7 mil compression molded
film in a 2 inch diameter cylinder. At the bottom of the cylinder
is a fine mesh screen that is 75 micronmeter or less. A Teflon disk
is placed on top of the film sample to secure it in place during
the testing. The cylinder containing the sample is placed on top of
4 inch glass fret so that the film sample and screen faced the
glass fret. A filter paper is placed between the cylinder and the
glass fret. The glass fret, filter and the cylinder is placed in a
container that contains water so that the height of the water
reaches the height of the glass fret. The water continuously being
removed and replenished. The entire set up sits on a Mettler
PG3001-S balance. Once the cylinder containing the sample is placed
on the balance, the balance is tared and water absorption and water
absorption rate data is generated using a Mettler BalanceLink data
acqusition software package. Table 6 lists the compositions for
Examples 43 to 46 and their water adsorption amounts and rates.
6TABLE 6 Time to reach Time to reach Thermoplastic AMPACET 50% of
maximum superabsorbent polymer, Water absorption value, absorption
value, Example polymer, parts parts Absorption, g sec sec 43 100 0
1 55 225 44 90 10 2.2 40 80 45 80 20 2.6 60 120 46 20 80 1.4 45 80
Thermoplastic superabsorbent polymer = 60 weight percent 50:50
PRIMACOR 5980;PRIMACOR 3460 polymer blend + 40 weight percent
CABLOC T5066-F
Multilayer Films
[0062] Comparative Examples AX to AZ and Examples 47 to 49 are
multilayer films of thermoplastic superabsorbent polymer blend
compositions produced using a blown film process. The extruder
temperature zones for the thermoplastic superabsorbent polymer
blend composition (layer 1) range from 250.degree. F. to
300.degree. F. Depending on the polymer used, the extruder
temperature zones for layers 2 and 3 range from 250.degree. F. to
400.degree. F. and die temperatures range from 250.degree. F. to
400.degree. F. The compositions and descriptions of multilayer
blown film Comparative Examples AX to AZ and Examples 47 to 49 are
shown in Table 7.
[0063] Examples 50 to 53 are multilayer blown films prepared as
described herein above wherein the level of CABLOC 850-13 is varied
in a PRIMACOR blend resin while the composition and ratios of
layers 2 and 3 are kept constant. The absorption capacity as
described hereinabove and the time to gel block in pure water is
determined. The time for the superabsorbent polymer to gel the
water at its absorption capacity in pure water for the
superabsorbent films, referred to as gel block, is measured
according to the following procedure. A sample of the thermoplastic
superabsorbent film composition comprising 0.15 gram of
superabsorbent polymer in a vial containing 25.6 grams of distilled
water. The mixture was shaken by hand until it was gel blocked. The
swell initiation time is the time from when the water is added to
the first observable swelling of the superabsorbent polymer.
[0064] Table 8 lists the compositions and film gauge for multilayer
films Comparative Example AAA and Examples 50 to 53. Table 9 lists
the water absorption, swell initiation time and time to gel block
properties for multilayer films Comparative Examples AAA and
Examples 50 to 53 and neat CABLOC 850-13 (Comparative Example
AAB).
7TABLE 7 Exam- Com. Layer ratio Gauge ple Ex. Layer 1 composition
Layer 2 composition Layer 3 composition 1 2 3 mils Product
description AX 20 parts CABLOC 1181 100% ATTANE 4201 100% PRIMACOR
3330 20 60 20 4.0 Frequent pinholes in film, 80 parts LDPE 681 die
face build-up AY 30 parts CABLOC 1181 20% ATTANE 4201 100% PRIMACOR
3330 20 60 20 2.0 Frequent pinholes in film, 70 parts ELVAX 3180
80% LDPE 681 die face build-up AZ 30 parts CABLOC 80HS 100% ATTANE
4201 100% PRIMACOR 3330 20 60 20 4.5 Some pinholes in film, die 70
parts PRIMACOR 3330 face build-up 47 40 parts CABLOC 80HS 30%
ATTANE 4201 100% PRIMACOR 3330 30 50 20 1.0-2.3 Ran well, no
pinholes, no 60 parts PRIMACOR 3460 70% LDPE 681 die face build-up.
48 40 parts CABLOC 88HS 50% ENGAGE 8100 100% PRIMACOR 3330 30 50 20
2.3 Ran well, no pinholes, no 60 parts ELVALOY 4924 50% LDPE 681
die face build-up. 49 40 parts CABLOC 850-13 80% ATTANE 4402 100%
PRIMACOR 3330 30 50 20 2.3 Ran well, no pinholes, no 60 parts
PRIMACOR 20% LDPE 681 die face build-up. blend (a) (a) 50:50 blend
of PRIMACOR 3460/PRIMACOR 5980
[0065]
8 TABLE 8 Layer ratio Gauge Example Com. Ex. Layer 1 composition
Layer 2 composition Layer 3 composition 1 2 3 mils AAA 100%
PRIMACOR blend (a) 80% ATTANE 4201 100% PRIMACOR 3330 30 50 20 4.0
20% LDPE 681 50 10 parts CABLOC 850-13 80% ATTANE 4201 100%
PRIMACOR 3330 30 50 20 2.0 90 parts PRIMACOR blend (a) 20% LDPE 681
51 20 parts CABLOC 850-13 80% ATTANE 4201 100% PRIMACOR 3330 30 50
20 4.5 80 parts PRIMACOR blend (a) 20% LDPE 681 52 30 parts CABLOC
850-13 80% ATTANE 4201 100% PRIMACOR 3330 30 50 20 1.0-2.3 70 parts
PRIMACOR blend (a) 20% LDPE 681 53 40 parts CABLOC 850-13 80%
ATTANE 4201 100% PRIMACOR 3330 30 50 20 2.3 60 parts PRIMACOR blend
(a) 20% LDPE 681 (a) 50:50 blend of PRIMACOR 3460/PRIMACOR 5980
[0066]
9TABLE 9 Com. Water Swell Initiation Time to Gel Example Ex.
Absorption, g Time, sec Block, sec AAA 0 50 127.25 <15 Did not
gel block 51 203.3 <15 840-900 52 225.9 <10 360-420 53 257.65
<5 90-200 AAB 180.0 <5 60-90
Multilayer Films Coated with a Surfactant Solution
[0067] Examples 54 to 57 use a 2.0 mil multilayer blown film. The
multilayer film comprises as layer 1 a thermoplastic superabsorbent
polymer blend comprising 60 weight percent of a 50:50 blend of
PRIMACOR 3460/PRIMACOR 5980 and 40 weight percent CABLOC T5066 F,
as layer 2 a LDPE 4005 and as layer 3 PLEXAR 107 an EVA g-MAH from
Equistar. The extruder temperature zones for the thermoplastic
superabsorbent polymer blend composition (layer 1) range from
250.degree. F. to 300.degree. F., the zone temperatures for layer 2
range from 305.degree. F. to 310.degree. F. and the zone
temperatures for layer 3 range from 350.degree. F. to 370.degree.
F. The thickness ratio for layers 1:2:3 is 30:50:20. Layer 1, the
thermoplastic superabsorbent layer, of the multilayer film is
sprayed with a surfactant solution ranging from 0 to 8 percent
surfactant. The surfactant used for the study is an alcohol ether
sulfate. After the film is sprayed, it is placed in an air
circulating oven to dry at a temperature of 50.degree. C. for 1-2
minutes. Water absorption and rate of absorption is measured
according to procedures in the aforementioned section. Table 10
summarizes the water absorption amounts and rates for Examples 54
to 57.
10TABLE 10 Time to Time to Time to reach reach initial 50% of
maximum Surfactant Water absorp- absorption absorption solution,
Absorption, tion, value, value, Example % g sec sec sec 54 0 1.7 15
60 170 55 2 2.0 0 31 112 56 5 1.9 0 29 160 57 8 1.8 0 27 135
Superabsorbent Film and Metal Laminate
[0068] Example 58 is the multilayer film described in Example 53
laminated to 6.0 mils Electrically Chrome Coated Steel (ECCS) via a
heat lamination process. The adhesive layer of the film (layer 3)
is used to bond the film to the steel surface. The superabsorbent
film/metal laminate can find usefulness in power cable and
communication cable construction. The metallic substrate can
provide shielding and the thermoplastic superabsorbent polymer
layer can be used to bond to itself or another substrate and can
function to stop, block and absorb water in cables. Table 11 shows
the adhesion properties for Example 57 superabsorbent film and
metal laminate.
11TABLE 11 Peel Strength (a), Heat Seal (a) Jacket (b) Bond Example
Film Metal Type (lb/in) Strength, (lb/in) Strength, (lb/in) 58
Example 53 ECCS 5.0 13.1 31.8 (a) Peel strength and heat seal
strength are measured according to ASTM B 736 and heat seal
strength is the bond strength of the thermoplastic superabsorbent
polymer to itself. (b) Jacketing material is DFDD 6069 BK 9865 a
modified LLDPE which is a standard wire and cable jacketing resin
manufactured by Union Carbide. Jacket bond (composite of jacketing
material and laminate fabricated in a platen press) strength
measures the force to separate the jacket from the laminate, values
is measured according to ASTM D 4365-86 modified to hold the sample
at 180.degree. C. ECCS = electrically chrome coated steel
Armored Cable
[0069] Superabsorbent films were laminated to the ECCS and slit
into 2.25 inch wide steel tape. The tape is used to make armored
cables Examples 59 to 62. The steel tape is corrugated to 32
corrugations per inch (corrugation can be achieved with or without
oil). The corrugated tape is longitudinal formed through a series
of forming dies. A PVC jacketed insulated copper pair cable core
having an outside diameter of 0.60 inch is placed inside the formed
armored tape. A jacketing resin is then extruded onto the formed
armor tape to make a final cable having a final outside diameter of
0.742 inch. The final gap between the inner jacket and the armor
tape is calculated to be around 0.015 inch (0.381 mm).
[0070] The performance of cables comprising the thermoplastic
superabsorbent polymer laminate (Examples 59 to 62, Table 12) is
compared to cables comprising ZETABON CJBS262 armor tape available
from the Dow Chemical Company (Comparative Example AAC) and
additionally comprising a non-woven superabsorbent tape 3E252
produced by Lantor Inc. (Comparative Example AAD). Non-woven
superabsorbent tapes are the wire and cable industry standard for
use in dry cable designs. The non-woven superabsorbent tape
comprises superabsorbent particles sandwiched between two non-woven
materials. For this evaluation, the non-woven superabsorbent tape
is helically wrapped around the copper pair cable core before
placing the cable core inside the formed armor tape. In the wire
and cable industry, the non-woven superabsorbent tape is typically
longitudinal formed around the cable core.
[0071] Water blocking performance of the cables is determined by
the EIA/TIA-455-82A ("L-test"). The end of the cable core is taped
or sealed so that water can not migrate through the wires of the
cable core. The cable length is 1 meter, test duration is 24 hours,
the water column is 1 meter and time to penetration is
measured.
12 TABLE 12 Laminate composition Metallic Example Com. Ex. Film
Layer 1 Core Film Layer 2 Non-woven tape Time to penetration AAC
EAA film 6 mil ECCS EAA film No Within 1 minute AAD EAA film 6 mil
ECCS EAA film Yes (a) 59 EAA film 6 mil ECCS Film 1 No No
penetration 60 EAA film 6 mil ECCS Film 2 No No penetration 61 EAA
film 6 mil ECCS Film 3 No No penetration 62 EAA film 6 mil ECCS
Film 4 No No penetration (a) test results vary from no penetration
to penetration occurring between 15-24 hours EAA film = 90%
PRIMACOR 3330/10% PE Film 1 composition: Layer 1: 30%-40 parts
CABLOC 850-13/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980) Layer 2:
50%-80% ATTANE 4201/20% LDPE 681 Layer 3: 20%-PRIMACOR 3330 Film 2
composition: Layer 1: 30%-40 parts CABLOC 8OHS/60 parts (50/50
PRIMACOR 3460/PRIMACOR 5980) Layer 2: 50%-80% ATTANE 4201/20% LDPE
681 Layer 3: 20%-PRIMACOR 3330 Film 3 composition: Layer 1: 30%-40
parts CABLOC 1181/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980)
Layer 2: 50%-80% ATTANE 4201/20% LDPE 681 Layer 3 20%-PRIMACOR 3330
Film 4 composition: Layer 1 30%-40 parts CABLOC 8OHSB/60% (50/50
PRIMACOR 3460/PRIMACOR 5980) Layer 2 50%-80% ATTANE 4201/20% LDPE
681 Layer 3 20%-PRIMACOR 3330 CABLOC 8OHSB has a particle size
distribution from about 1 to about 20 micrometers Film Layer 1 is
the side of the laminate that is used to bond to the jacketing
resin Film Layer 2 is the side of the laminate that was facing the
core
Armor Cable with Thermoplastic Superabsorbent Polymer Coated with a
Surfactant
[0072] Superabsorbent films were laminated to the ECCS. The
superabsorbent layer of the film is either pre- or post-coated with
an alcohol ether sulfate surfactant solution. The concentration of
the surfactant solution ranges from 2 weight percent to 8 weight
percent. An antifoaming agent, Dow Coming Anti Foam 1520-US, is
also used. The amount of antifoam used is 2500 ppm. The coated
laminate is slit into 1.375 inch wide steel tape. The tape is used
to make armored cables Examples 63 to 68 (Table 13). The steel tape
is corrugated to 32 corrugations per inch (corrugation can be
achieved with or without oil). The corrugated tape is longitudinal
formed through a series of forming dies. An HDPE core tube,
available from United States Plastic Corporation, having an outside
diameter of 0.375 inch is placed inside the formed armored tape. A
jacketing resin is then extruded onto the formed armor tape to make
a final cable. The final gap between the inner jacket and the armor
tape is calculated to be around 0.020 inch (0.508 mm).
[0073] The performance of cables comprising the thermoplastic
superabsorbent polymer laminate (Examples 63 to 68) is compared to
cables comprising ZETABON CJBS262 armor tape available from the Dow
Chemical Company (Comparative Example AAC).
[0074] Water blocking performance of the cables is determined by
the EIA/TIA-455-82A ("L-test"). The end of the cable core is taped
or sealed so that water can not migrate through the wires of the
cable core. The cable length is 1 meter, test duration is 24 hours,
the water column is 1 meter and time to penetration is
measured.
13 TABLE 13 Laminate composition Example Com. Ex. Film Layer 1
Metallic Core Film Layer 2 Surfactant treatment Time to penetration
AAC EAA film 6 mil ECCS EAA film Within 1 minute 63 EAA film 6 mil
ECCS Film 1 Pre- Pass 64 EAA film 6 mil ECCS Film 2 Pre- Pass 65
EAA film 6 mil ECCS Film 2 Post- Pass 66 EAA film 6 mil ECCS Film 2
Post- Pass 67 EAA film 6 mil ECCS Film 3 Post- Pass 68 EAA film 6
mil ECCS Film 3 Post- Pass EAA film = 90% PRIMACOR 3330/10% PE Film
1 composition: Layer 1: 30%-40 parts CABLOC 850-13/60 parts (50/50
PRIMACOR 3460/PRIMACOR 5980) Layer 2: 50%-LDPE 4005 Layer 3:
20%-PIEXAR 107 Film 2 composition: Layer 1: 30%-40 parts CABLOC
T5066 F/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980) Layer 2:
50%-LDPE 4005 Layer 3: 20%-PIEXAR 107 Film 3 composition: Layer 1:
30%-40 parts Norsocryl XFS/60 parts (50/50 PRIMACOR 3460/PRIMACOR
5980) Layer 2: 50%-LDPE 4005 Layer 3 20%-PIEXAR 107 Norsocryl is a
crosslinked copolymers of acrylic acid and sodium acrylate supplied
by elf atochem ATO PLEXAR 107 is a grafted maleic anhydride EVA
copolymer supplied by Equistar Film Layer 1 is the side of the
laminate that is used to bond to the jacketing resin Film Layer 2
is the side of the laminate that was facing the core
Foam Thermoplastic Superabsorbent Polymer
[0075] Examples 69 to 77 are extruded foams of thermoplastic
superabsorbent polymer blend compositions. About 12 parts per
hundred (pph) HCFC 142B physical blowing agent is used. The
extruder temperature zones range from 110.degree. C. to 150.degree.
C. and the die temperature range from 85.degree. C. to 90.degree.
C. The compositions and description of the foam are shown in Table
14. The resulting foams are soft, flexible and non-friable. The
superabsorbent particulates are uniformly distributed on the skin
and throughout the cell structure of the foam.
14TABLE 14 Thermoplastic superabsorbent Example polymer type Foam
type 69 1 Semi-porous to closed cell foam 70 2 Semi-porous to
closed cell foam 71 3 Semi-porous to closed cell foam 72 4
Semi-porous to closed cell foam 73 5 Semi-porous to closed cell
foam 74 6 Semi-porous to closed cell foam 75 7 Semi-porous to
closed cell foam 76 8 Semi-porous to closed cell foam 77 9
Semi-porous to closed cell foam 1 composition: 10 parts CABLOC
T5066 F/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980) 2 composition:
20 parts CABLOC T5066 F/60 parts (50/50 PRIMACOR 3460/PRIMACOR
5980) 3 composition: 30 parts CABLOC T5066 F/60 parts (50/50
PRIMACOR 3460/PRIMACOR 5980) 4 composition: 30 parts CABLOC 80
HS/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980) 5 composition: 20
parts CABLOC HCF/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980) 6
composition: 20 parts Norsocryl XFS/60 parts (50/50 PRIMACOR
3460/PRIMACOR 5980) 7 composition: 20 parts Norsocryl S35/60 parts
(50/50 PRIMACOR 3460/PRIMACOR 5980) 8 composition: 30 parts
Norsocryl S35/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980) 9
composition: 35 parts Norsocryl S35/60 parts (50/50 PRIMACOR
3460/PRIMACOR 5980) Norsocryl is a crosslinked copolymers of
acrylic acid and sodium acrylate supplied by elf atochem ATO
Norsocryl XFS particle size distribution range from 1-67
micronmeter Norsocryl S25 particle size distribution range form
1-225 micronmeter
[0076] The absorption capacity in pure water (WAC) of thermoplastic
superabsorbent foam Examples 78 to 80 (Table 15) extruded by the
abovementioned extrusion foam process is shown in Table 16. The WAC
is measured according to the following procedure: the foam is cut
in 0.125 inch by 0.625 in by 0.1.25 to 0.25 inch and an amount of
the cut foam sample determined to contained 0.1 gram of the
superabsorbent polymer (based on the percent superabsorbent polymer
in the foam composition) weighing W1 is placed in 0.150 liter of
distilled water and is shaken on a shaker for 2 hours. The water is
filtered from the foam through a 75 micrometer sieve. The weight of
the swollen foam (W2) is then measured. The amount of water
absorbed, (Wa) is calculate by the following formula:
Wa=(W2-W1)*10
[0077]
15TABLE 15 Thermoplastic superabsorbent polymer Example type Foam
Water absorption, g 78 2 Yes 87 79 3 Yes 67 80 3 Yes 43 2
composition: 20 parts CABLOC T5066 F/60 parts (50/50 PRIMACOR
3460/PRIMACOR 5980) 3 composition: 30 parts CABLOC T5066 F/60 parts
(50/50 PRIMACOR 3460/PRIMACOR 5980) 9 composition: 35 parts
Norsocryl S35/60 parts (50/50 PRIMACOR 3460/PRIMACOR 5980)
[0078] From these data it can be concluded that the extrudable
thermoplastic superabsorbent polymer blends of the present
invention comprising one or more superabsorbent polymer and one or
more thermoplastic resin wherein the thermoplastic resin comprises
a functional group that interacts with the superabsorbent polymer
yields the best balance of superabsorbent polymer containment,
processability, formability and absorption properties.
[0079] It has been found that the present invention provides
improved thermoplastic superabsorbent polymer blend compositions
and processes for preparing, among other things, monolayer films,
multilayer films, nonwoven webs, sheets, foams, profiles,
multilayer laminates, fibers, tubes, rods, pipes and the like. It
can be seen that the resulting parts or structures according to the
present invention are surprisingly improved by the use of the
described extrudable thermoplastic superabsorbent polymer blend
compositions and that extruded, shaped or otherwise fabricated
articles will ease manufacture, improve performance and reduce
costs of absorbent articles constructed therefrom.
* * * * *