U.S. patent application number 11/002615 was filed with the patent office on 2006-06-08 for intercalated layered silicate.
Invention is credited to Jeremy Bartels, Gary W. Beall, Michael L. Becraft, Michael D. Grah, Drew V. Speer.
Application Number | 20060122309 11/002615 |
Document ID | / |
Family ID | 36228800 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060122309 |
Kind Code |
A1 |
Grah; Michael D. ; et
al. |
June 8, 2006 |
Intercalated layered silicate
Abstract
An intercalated layered silicate comprises a layered silicate
and an intercalating agent sorbed between the silicate layers of
the layered silicate. The amount of intercalating agent is
effective to provide an average interlayer spacing between the
silicate layers of at least about 20 .ANG.. The intercalating agent
has a formula selected from formulas I through VII described
herein. The intercalated layered silicate may be exfoliated by
mixing it with a matrix medium and adding sufficient energy to form
a dispersed-particle composition. A packaging film, such as a food
packaging film, may comprise the dispersed-particle
composition.
Inventors: |
Grah; Michael D.;
(Simpsonville, SC) ; Becraft; Michael L.; (Greer,
SC) ; Speer; Drew V.; (Simpsonville, SC) ;
Beall; Gary W.; (San Marcos, TX) ; Bartels;
Jeremy; (New Braunfels, TX) |
Correspondence
Address: |
Sealed Air Corporation
P.O. Box 464
Duncan
SC
29334
US
|
Family ID: |
36228800 |
Appl. No.: |
11/002615 |
Filed: |
December 2, 2004 |
Current U.S.
Class: |
524/445 ;
106/415 |
Current CPC
Class: |
C08K 9/04 20130101; C01B
33/44 20130101; Y10T 428/265 20150115; C08K 5/175 20130101; C08K
5/06 20130101; C08K 5/103 20130101; C08K 3/34 20130101 |
Class at
Publication: |
524/445 ;
106/415 |
International
Class: |
C09C 1/00 20060101
C09C001/00; C08K 9/04 20060101 C08K009/04 |
Claims
1. An intercalated layered silicate comprising: a layered silicate
comprising a plurality of silicate layers; and an intercalating
agent sorbed between the silicate layers in an amount effective to
provide an average interlayer spacing between the silicate layers
of at least about 20 .ANG., wherein the intercalating agent has a
formula selected from: ##STR5## wherein: R.sup.4 represents any of:
1) an acyl group having at least 8 carbon atoms; 2) an alkyl group
having at least 8 carbon atoms; 3) an alkenyl group having at least
8 carbon atoms; 4) an alkadienyl group having at least 8 carbon
atoms; and 5) a carbon chain group having at least 8 carbon atoms,
wherein the carbon chain group incorporates one or more pendant or
terminal groups selected from hydroxyl, carboxyl, epoxy,
isocyanate, aryl, and arylmethyl, wherein the arylmethyl group has
the formula ##STR6## wherein "Ar" represents an aryl group, and
R.sup.6 and R.sup.7 independently represent hydrogen, an acyl
group, an alkyl group, or an alkenyl group; R.sup.5represents H,
--CH.sub.3, --CH.sub.2CH.sub.3, or any of the groups represented by
R.sup.4; R.sup.8 represents an oxylated group having a formula
selected from: ##STR7## wherein "n" ranges from 2 to 12 and "x"
ranges from 4 to 14; and R.sup.1, R.sup.2, and R.sup.3 each
independently represents H, --CH.sub.3, --CH.sub.2CH.sub.3,
##STR8## or any of the groups represented by R.sup.4 and R.sup.8,
provided that at least two R.sup.1, R.sup.2, and R.sup.3 is H.
2. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula I.
3. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula II.
4. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula II.
5. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula IV.
6. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula V.
7. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula V and R.sup.8 represents an
oxylated group having a formula selected from: ##STR9##
8. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula VI.
9. The intercalated layered silicate of claim 1 wherein the
intercalating agent has the formula VII.
10. The intercalated layered silicate of claim 1 wherein R.sup.4 is
branched.
11. The intercalated layered silicate of claim 1 wherein R.sup.4 is
unbranched.
12. The intercalated layered silicate of claim 1 wherein R.sup.4 is
an acyl group.
13. The intercalated layered silicate of claim 1 wherein R.sup.4 is
an alkyl group.
14. The intercalated layered silicate of claim 1 wherein each of
R.sup.1, R.sup.2, and R.sup.3 is a hydrogen.
15. The intercalated layered silicate of claim 1 wherein the
intercalating agent comprises an ester of pentaerythritol.
16. The intercalated layered silicate of claim 1 wherein the
intercalating agent comprises a fatty acid ester of
pentaerythritol.
17. The intercalated layered silicate of claim 1 wherein the
intercalating agent comprises pentaerythritol monostearate.
18. The intercalated layered silicate of claim 1 wherein the
intercalating agent comprises an ester of citric acid.
19. The intercalated layered silicate of claim 1 wherein the
intercalating agent comprises a fatty acid ester of citric
acid.
20. The intercalated layered silicate of claim 1 wherein the
intercalating agent comprises stearyl citrate.
21. The intercalated layered silicate of claim 1 wherein the
intercalated layered silicate is essentially free of an
intercalating agent comprising an ammonium compound.
22. The intercalated layered silicate of claim 1 wherein the
intercalated layered silicate is essentially free of an
intercalating agent comprising onium functionality.
23. The intercalated layered silicate of claim 1 wherein the amount
of sorbed intercalating agent is at least about 5 weight parts per
100 weight parts layered silicate.
24. The intercalated layered silicate of claim 1 wherein the
average interlayer spacing between the silicate layers is at least
about 30 .ANG..
25. The intercalated layered silicate of claim 1 wherein the
layered silicate is a bentonite clay.
26. The intercalated layered silicate of claim 1 having a peak
degradation temperature of at least about 360.degree. C.
27. A method of exfoliating a layered silicate comprising: mixing
from about 0.1 to about 100 weight parts of the intercalated
layered silicate of claim 1 with 100 weight parts of a matrix
medium to form a mixture; and adding sufficient energy to the
mixture to form a dispersed-particle composition comprising at
least about 0.1 weight parts exfoliated particles per 100 weight
parts matrix medium.
28. The method of claim 27 wherein the exfoliated particles have an
average dimension in the shortest dimension of at most about 100
nm.
29. The method of claim 27 wherein the matrix medium comprises one
or more polymers selected from polyolefin, ethylene/vinyl alcohol
copolymer, ionomer, vinyl plastic, polyamide, polyester, and
polystyrene.
30. The method of claim 27 wherein the matrix medium comprises one
or more energy curable polymer precursors.
31. The method of claim 27 wherein the matrix medium comprises one
or more materials selected from coating solvents, coating binders,
and coating resins.
32. The method of claim 27 wherein the matrix medium comprises one
or more materials selected from ink solvents and ink resins.
33. The method of claim 27 wherein the matrix medium comprises one
or more materials selected from grease lubricating oils and grease
gelling agents.
34. The method of claim 27 wherein the matrix medium comprises one
or more materials selected from cosmetic lipids, cosmetic
emollients, cosmetic humectants, cosmetic film formers, cosmetic
binders, cosmetic surfactants, and cosmetic solvents.
35. The method of claim 27 wherein the matrix medium comprises one
or more pharmaceutical excipients.
36. The method of claim 27 wherein the matrix medium comprises an
emulsion selected from an oil-in-water emulsion and a water-in-oil
emulsion.
37. The method of claim 27 comprising mixing from about 1 to about
10 weight parts of the intercalated layered silicate of claim 1
with 100 weight parts of a matrix medium.
38. The method of claim 27 comprising adding sufficient energy to
the mixture to form a dispersed-particle composition comprising at
least about 1 weight parts exfoliated particles per 100 weight
parts matrix medium.
39. A dispersed-particle composition comprising: at least about 50
weight % of a matrix medium; and from at least about 0.1 to at most
about 50 weight % of particles dispersed in the matrix medium, the
particles having an average size in the shortest dimension of at
most about 100 nm, the particles comprising: silicate platelets;
and an intercalating agent sorbed to the silicate platelets, the
intercalating agent having a formula selected from formulas I
through VII of claim 1.
40. The dispersed-particle composition of claim 39 wherein the
matrix medium comprises one or more polymers selected from
polyolefin, ethylene/vinyl alcohol copolymer, ionomer, vinyl
plastic, polyamide, polyester, and polystyrene.
41. A packaged food comprising: a package comprising the
dispersed-particle composition of claim 39; and a food enclosed in
the package.
42. A packaging film comprising the dispersed-particle composition
of claim 39, wherein the matrix medium comprises one or more
polymers, wherein the one or more polymers are thermoplastic.
43. A method of packaging a food comprising: enclosing a food in a
package comprising the packaging film of claim 42.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to intercalated layered
silicates and to dispersed-particle compositions comprising
silicate platelets exfoliated from intercalated layered
silicates.
[0002] Intercalated clays may be made using a quaternary
ammonium-based intercalating agent. However, it may be difficult to
obtain government agency approval to utilize quaternary
ammonium-based intercalating agents in some end-use applications,
such as food-contacting materials. Further, quaternary
ammonium-based intercalating agents may show an unacceptably high
amount of decomposition at the processing resident times and
temperatures desired for processing a matrix medium incorporating
the quaternary ammonium-based intercalating agent.
SUMMARY OF THE INVENTION
[0003] One or more embodiments of the present invention may address
one or more of the aforementioned problems.
[0004] An intercalated layered silicate comprises a layered
silicate and an intercalating agent sorbed between the silicate
layers of the layered silicate. The amount of intercalating agent
is effective to provide an average interlayer spacing between the
silicate layers of at least about 20 .ANG.. The intercalating agent
has a formula selected from formulas I through VII as described
below.
[0005] The intercalated layered silicate may be exfoliated by
mixing it with a matrix medium and adding sufficient energy to form
a dispersed-particle composition. A packaging film, such as a food
packaging film, may comprise the dispersed-particle
composition.
[0006] These and other objects, advantages, and features of the
invention will be more readily understood and appreciated by
reference to the detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is an X-ray diffraction pattern for montmorillonite
clay intercalated with pentaerythritol monostearate, as discussed
in Example 1;
[0008] FIG. 2 is an X-ray diffraction pattern for non-intercalated
montmorillonite clay;
[0009] FIG. 3 is an X-ray diffraction pattern for montmorillonite
clay intercalated with dimethyl didehydrogenated tallow quaternary
ammonium intercalated montmorillonite, as discussed in Comparative
1;
[0010] FIG. 4 is an X-ray diffraction pattern for montmorillonite
clay intercalated with pentaerythritol monostearate dispersed in a
matrix medium of linear low density polyethylene, as discussed in
Example 3;
[0011] FIG. 5 is an X-ray diffraction pattern for montmorillonite
clay intercalated with pentaerythritol monostearate dispersed in a
matrix medium of isotactic polypropylene, as discussed in Example
4;
[0012] FIG. 6 is an X-ray diffraction pattern for montmorillonite
clay intercalated with pentaerythritol monostearate dispersed in a
matrix medium of ethylene/vinyl acetate copolymer, as discussed in
Example 5;
[0013] FIG. 7 is an X-ray diffraction pattern for montmorillonite
clay intercalated with pentaerythritol monostearate dispersed in a
matrix medium of nylon-6 polymer, as discussed in Example 6;
[0014] FIG. 8 is a thermogravimetric analysis (TGA) graph for the
Example 1 PEMS intercalated montmorillonite clay; and
[0015] FIG. 9 is a thermogravimetric analysis (TGA) graph obtained
for the Comparative Sample 1 Cloisite 20A intercalated clay.
DETAILED DESCRIPTION OF THE INVENTION
[0016] An intercalated layered silicate comprises a layered
silicate comprising a plurality of silicate layers. An
intercalating agent is sorbed between the silicate layers in an
amount effective to provide an average interlayer spacing between
the silicate layers of at least about 20 .ANG..
Layered Silicate
[0017] The intercalated layered silicate comprises a layered
silicate. The layered silicate (i.e., phyllosilicate) may be
naturally occurring or synthetically derived. Exemplary layered
silicates include:
[0018] 1. Natural clays such as smectite clays, for example,
bentonite clays (e.g., montmorillonite, hectorite), mica,
vermiculite, nontronite, beidellite, volkonskoite, and
saponite;
[0019] 2. Layered polysilicates (e.g., layered silicic acid), such
as kanemite, makatite, ilerite, octosilicate, magadiite, and
kenyaite; and
[0020] 3. Synthetic clays, such as, synthetic silicates, synthetic
mica, synthetic saponite, synthetic laponite, and synthetic
hectorite.
[0021] Layered silicates comprise a plurality of silicate layers,
that is, a laminar structure having a plurality of stacked silicate
sheets or layers with a variable interlayer distance between the
layers. For example, the layered silicate may have a 2:1 layer
structure typified by an octahedral layer, comprising aluminum or
magnesium, sandwiched between two tetrahedral silicate layers. The
layers of the layered silicate may be turbostratic relative to each
other, such that the layered silicate may be swellable, for
example, in water. The average thickness of the silicate layers may
be at least about any of the following: 3, 5, 8, 10, 15, 20, 30,
40, and 50 .ANG.; and at most about any of the following: 60, 50,
45, 35, 25, 20, 15, 12, 10, 8, and 5 .ANG.. For example, many
layered silicates have a silicate layer thickness ranging from 8 to
11 .ANG..
[0022] The average interlayer spacing of the layered silicate at
60% relative humidity before intercalation with the intercalating
agent may be at least about any of the following: 1, 2, 3, 4, 5, 6,
8, and 10 .ANG.; and may be at most about any of the following: 20,
15, 10, 8, 6, 5, 3, and 2 .ANG..
[0023] The average interlayer spacing (i.e., the gallery spacing)
of a layered silicate (including an intercalated layered silicate)
refers to the distance between the internal faces of the
non-exfoliated, adjacent layers of representative samples of the
layered silicate. The interlayer spacing may be calculated using
standard powder wide angle X-ray diffraction techniques generally
accepted in the art in combination with Bragg's law equation, as is
known in the art.
[0024] Useful layered silicates are available from various
companies including Nanocor, Inc., Southern Clay Products, Kunimine
Industries, Ltd., and Rheox.
Intercalating Agent
[0025] The intercalated layered silicate comprises an intercalating
agent sorbed between the silicate layers of the layered silicate.
The term "sorbed" in this context means inclusion within the
layered silicate (for example, by adsorption and/or absorption)
without covalent bonding. An intercalating agent that is sorbed
between silicate layers may be held to the interlayer surface of a
silicate layer by one or more of ionic complexing, electrostatic
complexing, chelation, hydrogen bonding, ion-dipole interaction,
dipole-dipole interaction, and van der Waals forces.
[0026] The intercalating agent may have any one or more of the
following formulas: ##STR1##
[0027] R.sup.4 may represent an acyl group, for example, an acyl
group having at least any of 8, 10, 12, 14, and 16 carbon atoms;
and/or at most any of 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and
10 carbon atoms. The acyl group may be branched or unbranched. The
acyl group may be saturated or unsaturated (for example, with any
of one, two, three, or at least four units of unsaturation);
[0028] R.sup.4 may represent an alkyl group, for example, an alkyl
group having at least any of 8, 10, 12, 14, and 16 carbon atoms;
and/or at most any of 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and
10 carbon atoms. The alkyl group may be branched or unbranched;
[0029] R.sup.4 may represent an alkenyl group, for example, an
alkenyl group having at least any of 8, 10, 12, 14, and 16 carbon
atoms; and/or at most any of 30, 28, 26, 24, 22, 20, 18, 16, 14,
12, and 10 carbon atoms. The alkenyl group may be branched or
unbranched;
[0030] R.sup.4 may represent an alkadienyl group, for example, an
alkadienyl group having at least any of 8, 10, 12, 14, and 16
carbon atoms; and/or at most any of 30, 28, 26, 24, 22, 20, 18, 16,
14, 12, and 10 carbon atoms. The alkadienyl group may be branched
or unbranched.
[0031] R.sup.4 may represent a carbon chain group (branched or
unbranched), for example having at least any of 8, 10, 12, 14, and
16 carbon atoms; and/or at most any of 30, 28, 26, 24, 22, 20, 18,
16, 14, 12, and 10 carbon atoms, where the carbon chain group
incorporates one or more pendant or terminal groups selected from
each of a hydroxyl group, a carboxyl group, an epoxy group, an
isocyanate group, an aryl group (e.g., a phenyl group or a tolyl
group), and an arylmethyl group having the formula ##STR2## "Ar"
represents an aryl group. R.sup.6 and R.sup.7 may each
independently represent a hydrogen, an acyl group, an alkyl group,
or an alkenyl group.
[0032] R.sup.5 may represent any of H, --CH.sub.3,
--CH.sub.2CH.sub.3, and any of the groups represented by
R.sup.4.
[0033] R.sup.8 may represent oxylated groups selected from any one
or more of the following formulas: ##STR3## In the above formulas,
"n" may be at least any of the following values: 2, 4, 5, 6, 8, 10
and/or at most any of the following values: 6, 8, 10, 12; for
example, "n" may range from 4 to 12. In the above formulas, "x" may
be at least any of the following values: 4, 5, 6, 8, 10 and/or at
most any of the following values: 6, 8, 10, 12, 13, 14; for
example, "x" may range from 5 to 13.
[0034] R.sup.1, R.sup.2 and R.sup.3 may each independently
represent any of H, --CH.sub.3, --CH.sub.2CH.sub.3, ##STR4## and
any of the groups represented by R.sup.4 and R.sup.8, provided that
any of two, at least two, or three of R.sup.1, R.sup.2, and R.sup.3
may be H.
[0035] A branch R.sup.4 group may lack any branches (i.e., pendent
groups) having more than two carbons (e.g., ethyl group) or more
than one carbon (e.g., methyl group).
[0036] The R.sup.4 group may be compatible with the matrix medium
of expected use. In this sense, the R.sup.4 group of the
intercalating agent may facilitate the dispersion in the matrix
medium of the silicate platelets having sorbed intercalating agent,
such that a colloidal dispersion may be formed where the platelets
do not settle out of the matrix medium.
[0037] Exemplary intercalating agents having the formula I above
include fatty acid esters of pentaerythritol (i.e., fatty acid
esters of 2,2-bis-hydroxymethyl-1,3-propanediol), for example,
pentaerythritol monostearate ("PEMS"), pentaerythritol
monobehenate, pentaerythritol monooleate, pentaerythritol
ricinoleate, and pentaerythritol monolaurate. Other exemplary
intercalating agents having the formula I above are pentaerythityl
stearol (i.e.,
2-(hydroxymethyl)-2-[(octadecyloxy)methyl]-1,3-propanediol);
2-(hydroxymethyl)-2-[(4-cyclo-hexanebutyrate)methyl]-1,3-propanediol;
and
2-(hydroxymethyl)-2-[(4-phenylbutyrate)methyl]-1,3-propanediol.
[0038] Exemplary intercalating agents having the formula II above
include 1-hydroxy-2,2-bis(hydroxymethyl)octadecane;
1-hydroxy-2,2-bis(hydroxymethyl)tetradecane; and
1-hydroxy-2,2-bis(hydroxymethyl)dodecane. Exemplary intercalating
agents having the formula III above include
2-(hydroxymethyl)-2-[(octadecylamino)methyl]-1,3-propanediol.
Exemplary intercalating agents having the formula IV above include
2-(hydroxymethyl)-2-[(octadecylthio)methyl]-1,3-propanediol.
Exemplary intercalating agents having the formula V above include
2-(hydroxymethyl)-2-[(14-hydroxy-3,6,9,12-tetraoxadeacanoyl)methyl]-1,3-p-
ropandiol.
[0039] Exemplary intercalating agents having the formula VI above
include steroyl citric acid,
2-(octadecanoxy)-1,2,3-propanetricaboxylic acid,
2-(4-phenylbutanoxy)-1,2,3-propanetricaboxylic acid, and stearyl
citrate.
[0040] Suitable methods for the synthesis of compounds having the
above formulas are known to those of skill in the art, and may be
found, for example, in Advanced Organic Chemistry, 3.sup.rd Ed.,
Jerry March, John Wiley & Sons, New York, 1985, which is
incorporated herein in its entirety by reference.
[0041] The intercalating agent may be a nonionic intercalating
agent, that is, an intercalating agent that does not tend to form
or exchange ions, for example, in intercalating a layered
silicate.
[0042] The average interlayer spacing between the silicate layers
of the intercalated layered silicate may be at least about any of
the following: 20, 30, 40, 50, 60, 70, 80, and 90 .ANG.; and/or may
be at most about any of the following: 100, 90, 80, 70, 60, 50, 40,
30, 25 .ANG.. The amount of intercalating agent sorbed between the
silicate layers may be effective to provide any of the forgoing
average interlayer spacing between the silicate layers. The
measurement of the average interlayer spacing of the intercalated
layered silicate may be made at a relative humidity of 60%.
[0043] The amount of intercalating agent sorbed in the intercalated
layered silicate per 100 weight parts layered silicate may be at
least about and/or at most about any of the following: 5, 10, 20,
30, 50, 70, 90, 110, 150, 200, and 300 weight parts.
[0044] The intercalated layered silicate may be essentially free of
intercalating agent comprising onium functionality. The
intercalated silicate may be essentially free of any one, or of
all, or of any combination of the following compounds: ammonium
compounds, quaternary ammonium compounds, tertiary ammonium
compounds, secondary ammonium compounds, primary ammonium
compounds, phosponium compounds, quaternary phosponium compounds,
tertiary phosponium compounds, secondary phosponium compounds,
primary phosponium compounds, arsonium compounds, stibonium
compounds, oxonium compounds, and sulfonium compounds.
[0045] Exemplary ammonium compounds from which the intercalated
layered silicate may be essentially free include any one or any
combination of the following: alkyl ammonium compounds, such as
tetramethyl ammonium compounds, hexyl ammonium compounds, butyl
ammonium compounds, bis(2-hydroxyethyl)dimethyl ammonium compounds,
bis(2-hydroxyethyl)octadecyl methyl ammonium compounds, octadecyl
trimethyl ammonium compounds, octadecyl benzyl dimethyl ammonium
compounds, hexyl benzyl dimethyl ammonium compounds, benzyl
trimethyl ammonium compounds, butyl benzyl dimethyl ammonium
compounds, tetrabutyl ammonium compounds, dodecyl ammonium
compounds, di(2-hydroxyethyl)ammonium compounds, and
polyalkoxylated ammonium compounds.
[0046] Exemplary phosphonium compounds from which the intercalated
layered silicate may be essentially free include any one or any
combination of the following: alkyl phosphonium compounds, such as
tetrabutyl phosphonium compounds, trioctyl octadecyl phosphonium
compounds, tetraoctyl phosphonium compounds, octadecyl triphenyl
phosphonium compounds.
[0047] The intercalated layered silicate may be essentially free of
any intercalating agent comprising a compound selected from any or
all of the compounds listed in the previous three paragraphs.
Manufacture of the Intercalated Layered Silicate
[0048] To make the intercalated layered silicate, a layered
silicate is mixed with the intercalating agent to effect the
inclusion (i.e., sorption) of the intercalating agent in the
interlayer space between the silicate layers of the layered
silicate. In doing so, the resulting intercalated layered silicate
may be rendered organophilic (i.e., hydrophobic) and show an
enhanced attraction to an organic matrix medium.
[0049] In making the intercalated layered silicate, the
intercalating agent may first be mixed with a carrier, for example,
a carrier comprising one or more solvents such as water and/or
organic solvents such as ethanol to disperse or solubilize the
intercalating agent in the carrier. The intercalating agent/carrier
blend may subsequently be mixed with the layered silicate.
Alternatively, the layered silicate may be mixed with the carrier
to form a slurry, to which the intercalating agent may be added.
Also, the intercalating agent may be mixed directly with the
layered silicate without the benefit of a carrier. Intercalation
may be enhanced by addition of one or more of heat, pressure, high
shear mixing, ultrasonic cavitation, and microwave radiation to any
of the above systems.
[0050] The inclusion of the intercalation agent within the
interlayer spaces between the silicate layers of the layered
silicate increases the interlayer spacing between adjacent silicate
layers. This may disrupt the tactoid structure of the layered
silicate to enhance the dispersibility of the intercalated layered
silicate in the matrix medium, as discussed below.
[0051] The intercalating agent sorbed between the silicate layers
may be an amount and/or type effective to increase the interlayer
spacing between the silicate layers--relative to the spacing before
the sorption of the intercalating agent--by at least about any of
the following: 5, 6, 7, 8, 10, 12, 14, 15, 18, 20, 30, 40, 50, 60,
70, 80, and 90 .ANG.; and/or by at most about any of the following:
100, 90, 80, 70, 60, 50, 40, 30, 25, 20, 18, 15, 12, 10, 8, and 7
.ANG..
[0052] The intercalated layered silicate may be further treated to
aid dispersion and/or exfoliation in a matrix medium and/or improve
the strength of a resulting polymer/silicate interface. For
example, the intercalated layered silicate may be treated with a
surfactant to enhance compatibility with the matrix medium. Also by
way of example, the intercalated layered silicate may be further
intercalated with a compatibilizer, such as a polyolefin oligomer
having polar groups. An example is maleic anhydride modified olefin
oligomer or maleic anhydride modified ethylene vinyl acetate
oligomer. An oligomer may be modified (e.g., grafted) with
unsaturated carboxylic acid anhydride (i.e., anhydride-modified
oligomer) to incorporate anhydride functionality, which promotes or
enhances the adhesion characteristics of the oligomer. Examples of
unsaturated carboxylic acid anhydrides include maleic anhydride,
fumaric anhydride, and unsaturated fused ring carboxylic acid
anhydrides. Anhydride-modified polymer may be made by grafting or
copolymerization, as is known in the art. Useful anhydride-modified
oligomers may contain anhydride group in an amount (based on the
weight of the modified polymer) of at least about any of the
following: 0.1%, 0.5%, 1%, and 2%; and/or at most about any of the
following: 10%, 7.5%, 5%, and 4%.
[0053] The intercalated layered silicate may have a peak
degradation temperature of at least about any of the following:
360, 380, 390, 395, 400, 405, 410, 420, 430, and 440.degree. C.;
and/or at most about any of the following: 380, 390, 395, 400, 405,
410, 420, 430, 440, and 450.degree. C. The intercalated layered
silicate may have an onset temperature of degradation of at least
about any of the following: 200, 210, 220, 230, 240, 250, and
280.degree. C.; and/or at most about any of the following: 220,
230, 240, 250, 280, and 300.degree. C. The peak degradation
temperature and onset temperature of degradation may be determined
by thermogravimetric analysis (TGA) of the sample operating at a
20.degree. C. per minute scan rate from room temperature to
800.degree. C. in an argon purged atmosphere, and utilizing first
derivative of weight loss analysis. A useful TGA machine for such
analysis is the TGA Q50 model available from TA Instruments,
Inc.
Dispersed-Particle Composition
[0054] The intercalated layered silicate may be exfoliated to form
a dispersed-particle composition comprising a plurality of
dispersed particles comprising exfoliated silicate platelets
dispersed within a matrix medium. The dispersed particles may
comprise silicate platelets having sorbed intercalating agent of
the type previously discussed.
[0055] The matrix medium may comprise one or more polymers, for
example, one or more thermoplastic polymers, such as one or more
polymers selected from polyolefin, ethylene/vinyl alcohol
copolymer, ionomer, vinyl plastic, polyamide, polyester, and
polystyrene.
[0056] The matrix medium may comprise one or more energy curable
polymer precursors, for example, one or more energy curable
precursors selected from multifunctional acrylates or
methacrylates, thiol-ene systems, epoxy/amine or epoxy polyol
systems, and polyurethane precursors such as isocyanates and
polyols.
[0057] The matrix medium may comprise one or more compounds useful
in the formulation of paints, coatings, varnishes, greases,
cosmetics, or pharmaceutical excipients (either topical or
internal).
Polyolefins
[0058] The matrix medium may comprise one or more polyolefins.
Exemplary polyolefins include ethylene homo- and co-polymers and
propylene homo- and co-polymers. The term "polyolefins" includes
copolymers that contain at least 50 mole % monomer units derived
from olefin. Ethylene homopolymers include high-density
polyethylene ("HDPE") and low density polyethylene ("LDPE").
Ethylene copolymers include ethylene/alpha-olefin copolymers
("EAOs"), ethylene/unsaturated ester copolymers, and
ethylene/(meth)acrylic acid. ("Copolymer" as used in this
application means a polymer derived from two or more types of
monomers, and includes terpolymers, etc.)
[0059] EAOs are copolymers of ethylene and one or more
alpha-olefins, the copolymer having ethylene as the majority
mole-percentage content. The comonomer may include one or more
C.sub.3-C.sub.20 .alpha.-olefins, one or more C.sub.4-C.sub.12
.alpha.-olefins, and one or more C.sub.4-C.sub.8 .alpha.-olefins.
Useful .alpha.-olefins include 1-butene, 1-hexene, 1-octene, and
mixtures thereof.
[0060] Exemplary EAOs include one or more of the following: 1)
medium density polyethylene ("MDPE"), for example having a density
of from 0.926 to 0.94 g/cm3; 2) linear medium density polyethylene
("LMDPE"), for example having a density of from 0.926 to 0.94
g/cm3; 3) linear low density polyethylene ("LLDPE"), for example
having a density of from 0.915 to 0.930 g/cm3; 4) very-low or
ultra-low density polyethylene ("VLDPE" and "ULDPE"), for example
having density below 0.915 g/cm3, and 5) homogeneous EAOs. Useful
EAOs include those having a density of less than about any of the
following: 0.925, 0.922, 0.92, 0.917, 0.915, 0.912, 0.91, 0.907,
0.905, 0.903, 0.9, and 0.898 grams/cubic centimeter. Unless
otherwise indicated, all densities herein are measured according to
ASTM DI 505.
[0061] The polyethylene polymers may be either heterogeneous or
homogeneous. As is known in the art, heterogeneous polymers have a
relatively wide variation in molecular weight and composition
distribution. Heterogeneous polymers may be prepared with, for
example, conventional Ziegler-Natta catalysts.
[0062] On the other hand, homogeneous polymers are typically
prepared using metallocene or other single-site catalysts. Such
single-site catalysts typically have only one type of catalytic
site, which is believed to be the basis for the homogeneity of the
polymers resulting from the polymerization. Homogeneous polymers
are structurally different from heterogeneous polymers in that
homogeneous polymers exhibit a relatively even sequencing of
comonomers within a chain, a mirroring of sequence distribution in
all chains, and a similarity of length of all chains. As a result,
homogeneous polymers have relatively narrow molecular weight and
composition distributions. Examples of homogeneous polymers include
the metallocene-catalyzed linear homogeneous ethylene/alpha-olefin
copolymer resins available from the Exxon Chemical Company
(Baytown, Tex.) under the EXACT trademark, linear homogeneous
ethylene/alpha-olefin copolymer resins available from the Mitsui
Petrochemical Corporation under the TAFMER trademark, and
long-chain branched, metallocene-catalyzed homogeneous
ethylene/alpha-olefin copolymer resins available from the Dow
Chemical Company under the AFFINITY trademark.
[0063] Another exemplary ethylene copolymer is ethylene/unsaturated
ester copolymer, which is the copolymer of ethylene and one or more
unsaturated ester monomers. Useful unsaturated esters include: 1)
vinyl esters of aliphatic carboxylic acids, where the esters have
from 4 to 12 carbon atoms, and 2) alkyl esters of acrylic or
methacrylic acid (collectively, "alkyl(meth)acrylate"), where the
esters have from 4 to 12 carbon atoms.
[0064] Representative examples of the first ("vinyl ester") group
of monomers include vinyl acetate, vinyl propionate, vinyl
hexanoate, and vinyl 2-ethylhexanoate. The vinyl ester monomer may
have from 4 to 8 carbon atoms, from 4 to 6 carbon atoms, from 4 to
5 carbon atoms, and preferably 4 carbon atoms.
[0065] Representative examples of the second
("alkyl(meth)acrylate") group of monomers include methyl acrylate,
ethyl acrylate, isobutyl acrylate, n-butyl acrylate, hexyl
acrylate, and 2-ethylhexyl acrylate, methyl methacrylate, ethyl
methacrylate, isobutyl methacrylate, n-butyl methacrylate, hexyl
methacrylate, and 2-ethylhexyl methacrylate. The
alkyl(meth)acrylate monomer may have from 4 to 8 carbon atoms, from
4 to 6 carbon atoms, and preferably from 4 to 5 carbon atoms.
[0066] The unsaturated ester (i.e., vinyl ester or alkyl
(meth)acrylate)comonomer content of the ethylene/unsaturated ester
copolymer may range from about 6 to about 18 weight %, and from
about 8 to about 12 weight %, based on the weight of the copolymer.
Useful ethylene contents of the ethylene/unsaturated ester
copolymer include the following amounts: at least about 82 weight
%, at least about 85 weight %, at least about 88 weight %, no
greater than about 94 weight %, no greater than about 93 weight %,
and no greater than about 92 weight %, based on the weight of the
copolymer.
[0067] Representative examples of ethylene/unsaturated ester
copolymers include ethylene/methyl acrylate, ethylene/methyl
methacrylate, ethylene/ethyl acrylate, ethylene/ethyl methacrylate,
ethylene/butyl acrylate, ethylene/2-ethylhexyl methacrylate, and
ethylene/vinyl acetate.
[0068] Another useful ethylene copolymer is ethylene/(meth)acrylic
acid, which is the copolymer of ethylene and acrylic acid,
methacrylic acid, or both.
[0069] Useful propylene copolymer includes: 1) propylene/ethylene
copolymers ("EPC"), which are copolymers of propylene and ethylene
having a majority weight % content of propylene, such as those
having an ethylene comonomer content of less than 15%, less than
6%, and at least about 2% by weight and 2) propylene/butene
copolymers having a majority weight % content of propylene.
EVOH
[0070] Ethylene/vinyl alcohol copolymer ("EVOH") is another useful
thermoplastic. EVOH may have an ethylene content of about 32 mole
%, or at least about any of the following values: 20 mole %, 25
mole %, and 30 mole %. EVOH may have an ethylene content of below
about any of the following values: 50 mole %, 40 mole %, and 33
mole %. As is know in the art, EVOH may be derived by saponifying
or hydrolyzing ethylene/vinyl acetate copolymers, for example, to a
degree of hydrolysis of at least about any of the following values:
50%, 85%, and 98%.
Ionomer
[0071] Another useful thermoplastic is ionomer, which is a
copolymer of ethylene and an ethylenically unsaturated
monocarboxylic acid having the carboxylic acid groups partially
neutralized by a metal ion, such as sodium or zinc. Useful ionomers
include those in which sufficient metal ion is present to
neutralize from about 10% to about 60% of the acid groups in the
ionomer. The carboxylic acid is preferably "(meth)acrylic
acid"--which means acrylic acid and/or methacrylic acid. Useful
ionomers include those having at least 50 weight % and preferably
at least 80 weight % ethylene units. Useful ionomers also include
those having from 1 to 20 weight percent acid units. Useful
ionomers are available, for example, from Dupont Corporation
(Wilmington, Del.) under the SURLYN trademark.
Vinyl Plastics
[0072] Useful vinyl plastics include polyvinyl chloride ("PVC"),
vinylidene chloride polymer ("PVdC"), and polyvinyl alcohol
("PVOH"). Polyvinyl chloride ("PVC") refers to a vinyl
chloride-containing polymer or copolymer--that is, a polymer that
includes at least 50 weight percent monomer units derived from
vinyl chloride (CH.sub.2.dbd.CHCl) and also, optionally, one or
more comonomer units, for example, derived from vinyl acetate. One
or more plasticizers may be compounded with PVC to soften the resin
and/or enhance flexibility and processibility. Useful plasticizers
for this purpose are known in the art.
[0073] Another exemplary vinyl plastic is vinylidene chloride
polymer ("PVdC"), which refers to a vinylidene chloride-containing
polymer or copolymer--that is, a polymer that includes monomer
units derived from vinylidene chloride (CH.sub.2.dbd.CCl.sub.2) and
also, optionally, monomer units derived from one or more of vinyl
chloride, styrene, vinyl acetate, acrylonitrile, and
C.sub.1-C.sub.12 alkyl esters of (meth)acrylic acid (e.g., methyl
acrylate, butyl acrylate, methyl methacrylate). As used herein,
"(meth)acrylic acid" refers to both acrylic acid and/or methacrylic
acid; and "(meth)acrylate" refers to both acrylate and
methacrylate. Examples of PVdC include one or more of the
following: vinylidene chloride homopolymer, vinylidene
chloride/vinyl chloride copolymer ("VDC/VC"), vinylidene
chloride/methyl acrylate copolymer ("VDC/MA"), vinylidene
chloride/ethyl acrylate copolymer, vinylidene chloride/ethyl
methacrylate copolymer, vinylidene chloride/methyl methacrylate
copolymer, vinylidene chloride/butyl acrylate copolymer, vinylidene
chloride/styrene copolymer, vinylidene chloride/acrylonitrile
copolymer, and vinylidene chloride/vinyl acetate copolymer.
[0074] Useful PVdC includes that having at least about 75, at most
about 95, and at most about 98 weight % vinylidene chloride
monomer. Useful PVdC (for example, as applied by latex emulsion
coating) includes that having at least about any of 5%, 10%, and
15%--and/or at most about any of 25%, 22%, 20%, and 15 weight
%--comonomer with the vinylidene chloride monomer.
[0075] A layer that includes PVdC may also include a thermal
stabilizer (e.g., a hydrogen chloride scavenger such as epoxidized
soybean oil) and a lubricating processing aid (e.g., one or more
acrylates).
Polyamide
[0076] Useful polyamides include those of the type that may be
formed by the polycondensation of one or more diamines with one or
more diacids and/or of the type that may be formed by the
polycondensation of one or more amino acids and/or of the type
formed by the ring opening of cyclic lactams. Useful polyamides
include aliphatic polyamides and aliphatic/aromatic polyamides.
[0077] Representative aliphatic diamines for making polyamides
include those having the formula: H.sub.2N(CH.sub.2).sub.nNH.sub.2
where n has an integer value of 1 to 16. Representative examples
include trimethylenediamine, tetramethylenediamine,
pentamethylenediamine, hexamethylenediamine, octamethylenediamine,
decamethylenediamine, dodecamethylenediamine,
hexadecamethylenediamine. Representative aromatic diamines include
p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'
diaminodiphenyl sulphone, 4,4'-diaminodiphenylethane.
Representative alkylated diamines include
2,2-dimethylpentamethylenediamine,
2,2,4-trimethylhexamethylenediamine, and 2,4,4
trimethylpentamethylenediamine. Representative cycloaliphatic
diamines include diaminodicyclohexylmethane. Other useful diamines
include heptamethylenediamine, nonamethylenediamine, and the
like.
[0078] Representative diacids for making polyamides include
dicarboxylic acids, which may be represented by the general
formula: HOOC-Z-COOH where Z is representative of a divalent
aliphatic or cyclic radical containing at least 2 carbon atoms.
Representative examples include aliphatic dicarboxylic acids, such
as adipic acid, sebacic acid, octadecanedioic acid, pimelic acid,
suberic acid, azelaic acid, dodecanedioic acid, and glutaric acid;
and aromatic dicarboxylic acids, such as such as isophthalic acid
and terephthalic acid.
[0079] The polycondensation reaction product of one or more or the
above diamines with one or more of the above diacids may form
useful polyamides. Representative polyamides of the type that may
be formed by the polycondensation of one or more diamines with one
or more diacids include aliphatic polyamides such as
poly(hexamethylene adipamide) ("nylon-6,6"), poly(hexamethylene
sebacamide) ("nylon-6,10"), poly(heptamethylene pimelamide)
("nylon-7,7"), poly(octamethylene suberamide) ("nylon-8,8"),
poly(hexamethylene azelamide) ("nylon-6,9"), poly(nonamethylene
azelamide) ("nylon-9,9"), poly(decamethylene azelamide)
("nylon-10,9"), poly(tetramethylenediamine-co-oxalic acid)
("nylon-4,2"), the polyamide of n-dodecanedioic acid and
hexamethylenediamine ("nylon-6,12"), the polyamide of
dodecamethylenediamine and n-dodecanedioic acid
("nylon-12,12").
[0080] Representative aliphatic/aromatic polyamides include
poly(tetramethylenediamine-co-isophthalic acid) ("nylon-4,1"),
polyhexamethylene isophthalamide ("nylon-6,1"), polyhexamethylene
terephthalamide ("nylon-6,T"), poly (2,2,2-trimethyl hexamethylene
terephthalamide), poly(m-xylylene adipamide) ("nylon-MXD,6"),
poly(p-xylylene adipamide), poly(hexamethylene terephthalamide),
poly(dodecamethylene terephthalamide), and polyamide-MXD,I.
[0081] Representative polyamides of the type that may be formed by
the polycondensation of one or more amino acids include
poly(4-aminobutyric acid) ("nylon-4"), poly(6-aminohexanoic acid)
("nylon-6" or "poly(caprolactam)"), poly(7-aminoheptanoic acid)
("nylon-7"), poly(8-aminooctanoic acid) ("nylon-8"),
poly(9-aminononanoic acid) ("nylon-9"), poly(10-aminodecanoic acid)
("nylon-10"), poly(11-aminoundecanoic acid) ("nylon-11"), and
poly(12-aminododecanoic acid) ("nylon-12" or
"poly(lauryllactam)").
[0082] Representative copolyamides include copolymers based on a
combination of the monomers used to make any of the foregoing
polyamides, such as, nylon-4/6, nylon-6/6, nylon-6/9, nylon-6/12,
caprolactam/hexamethylene adipamide copolymer ("nylon-6,6/6"),
hexamethylene adipamide/caprolactam copolymer ("nylon-6/6,6"),
trimethylene adipamide/hexamethylene azelaiamide copolymer
("nylon-trimethyl 6,2/6,2"), hexamethylene
adipamide-hexamethylene-azelaiamide caprolactam copolymer
("nylon-6,6/6,9/6"), hexamethylene
adipamide/hexamethylene-isophthalamide ("nylon-6,6/6,I"),
hexamethylene adipamide/hexamethyleneterephthalamide
("nylon-6,6/6,T"), nylon-6,T/6,I, nylon-6/MXD,T/MXD,I,
nylon-6,6/6,10, and nylon-6,1/6,T.
[0083] Conventional nomenclature typically lists the major
constituent of a copolymer before the slash ("/") in the name of a
copolymer; however, in this application the constituent listed
before the slash is not necessarily the major constituent unless
specifically identified as such. For example, unless the
application specifically notes to the contrary, "nylon-6/6,6" and
"nylon-6,6/6" may be considered as referring to the same type of
copolyamide.
[0084] Polyamide copolymers may include the most prevalent polymer
unit in the copolymer (e.g., hexamethylene adipamide as a polymer
unit in the copolymer nylon-6,6/6) in mole percentages ranging from
any of the following: at least about 50%, at least about 60%, at
least about 70%, at least about 80%, and at least about 90%, and
the ranges between any of the forgoing values (e.g., from about 60
to about 80%); and may include the second most prevalent polymer
unit in the copolymer (e.g., caprolactam as a polymer unit in the
copolymer nylon-6,6/6) in mole percentages ranging from any of the
following: less than about 50%, less than about 40%, less than
about 30%, less than about 20%, less than about 10%, and the ranges
between any of the forgoing values (e.g., from about 20 to about
40%).
[0085] Useful polyamides include those that are approved by the
controlling regulating agency (e.g., the U.S. Food and Drug Agency)
for either direct contact with food and/or for use in a food
packaging film, at the desired conditions of use.
Polyesters
[0086] Useful polyesters include those made by: 1) condensation of
polyfunctional carboxylic acids with polyfunctional alcohols, 2)
polycondensation of hydroxycarboxylic acid, and 3) polymerization
of cyclic esters (e.g., lactone).
[0087] Exemplary polyfunctional carboxylic acids (and their
derivatives such as anhydrides or simple esters like methyl esters)
include aromatic dicarboxylic acids and derivatives (e.g.,
terephthalic acid, isophthalic acid, dimethyl terephthalate,
dimethyl isophthalate) and aliphatic dicarboxylic acids and
derivatives (e.g., adipic acid, azelaic acid, sebacic acid, oxalic
acid, succinic acid, glutaric acid, dodecanoic diacid,
1,4-cyclohexane dicarboxylic acid, dimethyl-1,4-cyclohexane
dicarboxylate ester, dimethyl adipate). Useful dicarboxylic acids
also include those discussed above in the polyamide section. As is
known to those of skill in the art, polyesters may be produced
using anhydrides and esters of polyfunctional carboxylic acids.
[0088] Exemplary polyfunctional alcohols include dihydric alcohols
(and bisphenols) such as ethylene glycol, 1,2-propanediol,
1,3-propanediol, 1,3 butanediol, 1,4-butanediol,
1,4-cyclohexanedimethanol, 2,2-dimethyl-1,3-propanediol,
1,6-hexanediol, poly(tetrahydroxy-1,1'-biphenyl, 1,4-hydroquinone,
and bisphenol A.
[0089] Exemplary hydroxycarboxylic acids and lactones include
4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, pivalolactone,
and caprolactone.
[0090] Useful polyesters include homopolymers and copolymers. These
may be derived from one or more of the constituents discussed
above. Exemplary polyesters include poly(ethylene terephthalate)
("PET"), poly(butylene terephthalate) ("PBT"), and poly(ethylene
naphthalate) ("PEN"). If the polyester includes a mer unit derived
from terephthalic acid, then such mer content (mole %) of the
diacid component of the polyester may be at least about any the
following: 70, 75, 80, 85, 90, and 95%.
[0091] The polyester may be thermoplastic. The polyester (e.g.,
copolyester) of the film may be amorphous, or may be partially
crystalline (semi-crystalline), such as with a crystallinity of at
least about, or at most about, any of the following weight
percentages: 10, 15, 20, 25, 30, 35, 40,and 50%.
Polystyrene
[0092] The matrix medium may comprise polystyrene. Exemplary
polysytrene includes stryrene homo- and co-polymers. Polystyrene
may be substantially atactic, syndiotactic or isotactic. The term
"polysytrene" includes copolymer that contains at least 50 mole %
monomer units derived from styrene. Styrene may be copolymerized
with alkyl acrylates, maleic anhydride, isoprene, or butadiene.
Styrene copolymers with isoprene and butadiene may be further
hydrogenated.
Energy Curable Polymer Precursors
[0093] The matrix medium may comprise one or more energy curable
polymer precursors. An energy curable polymer precursor is a
compound (e.g., monomer or oligomer) that is intended for
transformation to a cured polymer by the application of energy in
the form of heat and/or radiation (e.g., light), and may also
involve an initiator and/or catalyst. The resulting energy cured
polymer may be a thermoset polymer or a thermoplastic polymer. A
single energy curable polymer precursor may react to form a
polymer, or two or more energy curable polymer precursors may react
together to form a polymer. The energy curable polymer precursor
may be multifunctional, that is, adapted to form crosslinked
polymer when cured. The energy curable chemical reaction may be
induced by heat, catalyst interaction, radiation (e.g., light), or
mixing of the energy curable polymer precursors.
[0094] Useful energy curable polymer precursors may include one or
more of the energy curable polymer precursors that are precursors
to one or more of the following polymers: polyester resins (e.g.,
alkyd resin), allyl resins (e.g., diallyl phthalate, diallyl
isophtahalate, diallyl maleate, and diallyl chlorendate), amino
resins (e.g., urea resins, melamine resins, and their copolymers
with formaldehyde), epoxy resins, furan resins, phenolic resins
(e.g., phenol-aralkyl resins, phenol-formaldehyde resins),
polyacrylic ester resins, polyamide resins, polyurethane resins,
polyacrylamide resins, polyimide resins, and acrylamide resins.
[0095] Exemplary energy curable polymer precursors may include
(meth)acrylates (i.e., methacrylates and/or acrylates),
multifunctional (meth)acrylates, thiol-ene systems, and
maleimides.
[0096] Exemplary energy curable polymer precursors, for example,
with respect to polyurethane polymer precursors, may include
polyols and polyisocyanates (e.g., toluene diisocyanate and
diphenyl-methanediisocyanate).
[0097] With respect to the polyurethane and epoxy resin precursors,
for example, the intercalated layered silicate may be mixed with
the polyol precursor component rather than the more reactive
component to help minimize premature reaction.
Additional Matrix Medium
[0098] The matrix medium may comprise one or more compounds useful
in the formulation of one or more of any of the following: coatings
(i.e., paints and/or varnishes), inks, greases, cosmetics, and
pharmaceutical dosage forms.
[0099] The matrix medium may comprise one or more materials
selected from coating (i.e., paint and/or varnish) solvents,
coating binders, and coating resins. Useful coating solvents,
coating binders, and coating resins are known to those of skill in
the art; see, for example, those discussed in Paints and Coatings,
Ullmann's Encyclopedia of Industrial Chemistry, Volume 24, pages
591-790 (2003 Wiley-VCH), of which pages 591-790 are incorporated
herein by reference. Examples include mineral spirits, toluene, and
linseed oil.
[0100] The matrix medium may comprise one or more materials
selected from ink solvents and ink resins (e.g., ink binders and/or
ink vehicles). Useful ink solvents and ink resins are known to
those of skill in the art; see, for example, those discussed in
Leach and Pierce, The Printing Ink Manual (5.sup.th edition 1993),
which is incorporated herein in its entirety.
[0101] The matrix medium may comprise one or more materials
selected from grease lubricating oils and grease gelling agents.
Useful grease lubricating oils and grease gelling agents are known
to those of skill in the art; see, for example, those discussed in
Kirk-Othmer Encyclopedia of Chemical Technology, Volume 15, pages
493-98 (4.sup.th edition 1995), of which pages 493-98 are
incorporated herein by reference.
[0102] The matrix medium may comprise one or more materials useful
in the formulation of cosmetics, for example, one or more materials
selected from lipids, emollients, humectants, film formers,
binders, surfactants, and solvents. Useful cosmetic lipids,
emollients, humectants, film formers, binders, surfactants, and
solvents are known to those of skill in the art; see, for example,
those discussed in Kirk-Othmer Encyclopedia of Chemical Technology,
Volume 7, pages 572-619 (4.sup.th edition 1993), of which pages
572-619 are incorporated herein by reference, and CTFA
International Cosmetic Ingredient Handbook, 2.sup.nd edition (CTFA
Washington D.C. 1992), which is incorporated herein in its entirety
by reference.
[0103] Compounds useful in the formulation of pharmaceutical dosage
forms include pharmaceutical (e.g., medical) excipients (e.g.,
carriers). The matrix medium may comprise one or more
pharmaceutical excipients, for example, one or more excipients
adapted for an internal pharmaceutical dosage form and/or adapted
for an external pharmaceutical dosage form. Useful pharmaceutical
excipients are known to those of skill in the art; see, for
example, those discussed in Pharmaceutical Dosage Forms, Ullmann's
Encyclopedia of Industrial Chemistry, Volume 25, pages 515-547
(2003 Wiley-VCH), of which pages 515-547 are incorporated herein by
reference.
[0104] The matrix medium may comprise one or more of water, an
oil-in-water emulsion, and a water-in-oil emulsion.
Dispersed Particles
[0105] The dispersed particles in the dispersed-particle
composition may have an average size of less than about 100 nm in
at least one dimension. The particles may have an average aspect
ratio (i.e., the ratio of the average largest dimension to the
average smallest dimension of the particles) of from about 10 to
about 30,000. Typically, the aspect ratio for particles comprising
silicate platelets exfoliated from an intercalated layered silicate
may be taken as the length (largest dimension) to the thickness
(smallest dimension) of the platelets. For a particle having a
fiber configuration, the aspect ratio may be taken as the length
(largest dimension) to the diameter (smallest dimension) of the
particle.
[0106] Useful aspect ratios for the dispersed particles include at
least about any of the following values: 10; 20; 25; 200; 250;
1,000; 2,000; 3,000; and 5,000; and at most about any of the
following values: 25,000; 20,000; 15,000; 10,000; 5,000; 3,000;
2,000; 1,000; 250; 200; 25; and 20.
[0107] The dispersed particles may have an average size in the
shortest dimension of at least about any of the following values:
0.5 nm, 0.8 nm, 1 nm, 2, nm, 3 nm, 4 nm, and 5 nm; and at most
about any of the following values: 100 nm, 60 nm, 30 nm, 20 nm, 10
nm, 8 nm, 5 nm, and 3 nm, as estimated from transmission electron
microscope ("TEM") images. The particles may have an average
dimension small enough to maintain optical transparency of the
matrix medium in which the particles are dispersed.
[0108] The amount of exfoliated particles dispersed in the
dispersed-particle composition may be at least about any of the
following values 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 10 weight
%; and/or may be at most about any of the following values: 50, 40,
30, 20, 15, 10, 8, 6, 5, 4, 3, 2, and 1 weight %, based on the
weight of the dispersed-particle composition. Also, the amount of
exfoliated particles dispersed in the dispersed-particle
composition may be at least about any of the following values: 0.1,
0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 10 weight parts; and/or may be at
most about any of the following values: 100, 80, 60, 50, 40, 30,
20, 15, 10, 8, 6, 5, 4, 3, 2, and 1 weight parts, based on 100
weight parts of matrix medium, for example, based on 100 weight
parts of the one or more polymers discussed above.
[0109] The dispersed-particle composition may comprise at least
about any of the following: 50, 60, 70, 80, 90, 95, and 98 weight
%; and at most about any of the following: 99, 98, 95, 90, 80, 70,
and 60 weight %, based on the weight of the dispersed-particle
composition of any of the following: 1) the matrix medium, or 2)
the one or more polymers, or 3) the energy curable polymer
precursors, or 4) the coating solvents, coating binders, or coating
resins, or 5) the ink solvents or ink resins, or 6) the grease
lubricating oils or grease gelling agents, or 7) the cosmetic
lipids, cosmetic emollients, cosmetic humectants, cosmetic film
formers, cosmetic binders, cosmetic surfactants, or cosmetic
solvents, or 8) pharmaceutical excipients.
[0110] The particles may comprise silicate platelets derived from
the intercalated layered silicate and an intercalating agent sorbed
to the silicate platelets. Exemplary intercalating agents are
discussed above. The dispersed-particle composition may be
essentially free of intercalating agent comprising onium
functionality, such as any one, or of all, or of any combination of
the onium compounds discussed above.
[0111] The amount of intercalating agent sorbed to the silicate
platelets may be at least about and/or at most about any of the
following: 1, 5, 10, 20, 30, 50, 70, 90, 110, 150, 200, and 300
weight parts per 100 weight parts silicate platelets.
[0112] It is believed that exfoliated particles result when
individual silicate layers of a layered silicate are no longer
close enough to interact significantly with the adjacent layers via
ionic or van der Waals attractions or to form strongly correlated
systems due to the large aspect ratios of the platelets. An
exfoliated layered silicate has lost its registry and may be
relatively uniformly and randomly dispersed in a continuous matrix
medium. It is believed that the dispersion in a matrix medium
occurs when the interlayer spacing of the layered silicate is at or
greater than the average radius of gyration of the molecules
comprising the matrix medium.
[0113] A dispersing aid may be used to enhance exfoliation of the
intercalated layered silicate into the matrix medium. Exemplary
dispersing aids may include one or more of water, alcohols,
ketones, aldehydes, chlorinated solvents, hydrocarbon solvents, and
aromatic solvents.
Manufacture of the Dispersed-Particle Composition
[0114] The intercalated layered silicate may be exfoliated in a
matrix medium to form the dispersed-particle composition. The
intercalated layered silicate may be added to the matrix medium
under conditions effective to exfoliate at least a portion of the
intercalated layered silicate into particles comprising silicate
platelets dispersed in the matrix medium. An amount of intercalated
layered silicate mixed with the matrix medium may be at least about
any of the following: 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 10
weight parts intercalated layered silicate; and/or may be at most
about any of the following values: 100, 80, 60, 50, 40, 30, 20, 15,
10, 8, 6, 5, 4, 3, 2, and 1 weight parts intercalated layered
silicate, based on 100 weight parts of matrix medium, for example,
based on 100 weight parts of the one or more polymers discussed
above.
[0115] At least about any of the following amounts of the
intercalated layered silicate added to the matrix medium may be
dispersed as exfoliated particles having an average size of less
than about 100 nm in at least one dimension: 50, 60, 70, 80, 90,
95, 98, and 99 weight parts exfoliated particles per 100 weight
parts added intercalated layered silicate. The exfoliated silicate
platelets may have the average thickness of the individual layers
of the layered silicate, or may have as an average thickness
multiples of less than about any of 10, 5, and 3 layers of the
layered silicate. TEM images may be used to estimate the amount and
size and characteristics of the exfoliated particles.
[0116] The effective exfoliation conditions may include the
addition of mixing and/or shearing energy to the mixture of the
intercalated layered silicate and the matrix medium. The process
variables for exfoliating the intercalated layered silicate in the
matrix medium include time, temperature, geometry of the mixing
apparatus, and the shear rate, and generally requires a balance of
these variables, as is known to those of skill in the art. The
balancing of these variables may take into account the desire to
minimize the physical degradation or decomposition of the matrix
medium and/or the intercalating agent, for example, by limiting the
upper temperature of the processing and/or the amount of time at a
selected temperature during processing.
[0117] An increase in temperature generally provides more thermal
energy to enhance exfoliation. A decrease in temperature may lower
the viscosity of the mixture while increasing the shear rate. An
increase in shear rate generally enhances exfoliation. Shear rates
of at least about any of the following may be applied to the
mixture of the intercalated layered silicate and the matrix medium:
1 sec.sup.-1, 10 sec.sup.-1, 50 sect1, 100 sec.sup.-1, and 300
sec.sup.-1.
[0118] Illustrative methods or systems for applying shear to effect
exfoliation of the intercalated layered silicate in the matrix
medium include mechanical systems, thermal shock, pressure
alternation, and ultrasonics. A flowable mixture may be sheared by
mechanical methods, such as the use of stirrers, blenders, Banbury
type mixers, Brabender type mixers, long continuous mixers,
injection molding machines, and extruders. Twin screw extruders may
be useful, for example, for mixing the intercalated layered
silicate with a thermoplastic matrix medium. A thermal shock method
achieves shearing by alternatively raising and lowering the
temperature of the mixture to cause thermal expansions and
contractions to induce internal stresses that cause shear. Sudden
and alternating pressure changes may also be used to apply shear to
the mixture. Ultrasonic methods induce shear by cavitation or
resonant vibrations, which cause varying portions of the mixture to
vibrate and become excited at different phases.
[0119] The effective exfoliation conditions may comprise raising
the temperature of the matrix medium, for example a matrix medium
comprising one or more thermoplastic polymers, so that the matrix
medium is thermally processible at a reasonable rate in the
mechanical system either before, while, or after adding the
intercalated layered silicate to the matrix medium. During
processing, the mixture of the intercalated layered silicate and
the matrix medium may be at a temperature, for example, of at least
about and/or at most about any of the following temperatures:
100.degree. C., 150.degree. C., 200.degree. C., 240.degree. C.,
280.degree. C., 300.degree. C., 320.degree. C., 350.degree. C.,
380.degree. C., and 400.degree. C. The amount of residence time
that the mixture of the intercalated layered silicate and the
matrix medium may reside at any of these temperatures may be at
least about and/or at most about any of the following times: 2, 4,
5, 8, 10, 12, 15, and 20 minutes.
[0120] Before effecting exfoliation, the layered silicate may be
reduced in size by methods known in the art, including, but not
limited to, grinding, pulverizing, hammer milling, jet milling, and
their combinations, so that the average particle diameter of the
layered silicate may be, for example, less than about any of 100,
50, and 20 microns.
Use of the Intercalated Layered Silicate and Dispersed-Particle
Composition
[0121] The dispersed particles may be used to enhance the physical
and/or performance properties of the matrix medium in which they
are dispersed. For example, the dispersed particles may improve one
or more of the modulus, strength, permeability, rheological, and
surface adhesion properties of the matrix medium incorporating the
particles relative to the matrix medium without the particles.
[0122] Several types of products may benefit from incorporation of
the dispersed-particle composition to improve, for example,
performance properties. Exemplary products that may comprise the
dispersed-particle composition include:
[0123] sheets and panels, which, for example, may be further shaped
by pressing, molding, and/or thermoforming to form useful
objects;
[0124] coatings (i.e., paints and/or varnishes);
[0125] lubricants, for example, food-grade lubricants;
[0126] greases;
[0127] personal care products, such as cosmetics (e.g.,
antiperspirants, deodorants, facial makeup, decorative makeup,
toothpastes, shampoos, soaps, skin conditioners, skin moisturizers,
and sunscreens);
[0128] pharmaceuticals, such as topical medicinal compositions
(e.g., anti-fungal compositions, anti-bacterial compositions,
anesthetics, anti-inflammatory compositions, pain-relief ointments,
and rash/itch/irritation ointments) and internal medicinal
compositions (e.g., pills, tablets, capsules, powders, and
solutions); and
[0129] packaging materials, such as packaging films (e.g., shrink
films, stretch films, and food packaging films), bottles, trays,
and containers.
[0130] A packaging film may comprise one or more layers comprising
any of the dispersed-particle compositions discussed above. The
film may have any total thickness as long as it provides the
desired properties (e.g., free shrink, shrink tension, flexibility,
Young's modulus, optics, strength, barrier) for the given
application of expected use. The film may have a thickness of less
than about any of the following: 20 mils, 10 mils, 5 mils, 4 mils,
3 mils, 2 mils, 1.5 mils, 1.2 mils, and 1 mil. The film may also
have a thickness of at least about any of the following: 0.25 mils,
0.3 mils, 0.35 mils, 0.4 mils, 0.45 mils, 0.5 mils, 0.6 mils, 0.75
mils, 0.8 mils, 0.9 mils, 1 mil, 1.2 mils, 1.4 mils, 1.5 mils, 2
mils, 3 mils, and 5 mils.
[0131] The film may be monolayer or multilayer. The film may
comprise at least any of the following number of layers: 1, 2, 3,
4, 5, 6, 7, 8, and 9. The film may comprise at most any of the
following number of layers: 20, 15, 10, 9, 7, 5, 3, 2, and 1. The
term "layer" refers to a discrete film component which is
coextensive with the film and has a substantially uniform
composition. Any of the layers of the film may have a thickness of
at least about any of the following: 0.05, 0.1, 0.2, 0.5, 1, 2, and
3 mil. Any of the layers of the film may have a thickness of at
most about any of the following:. 20, 10, 5, 2, 1, and 0.5 mils.
Any of the layers of the film may have a thickness as a percentage
of the total thickness of the film of at least about any of the
following values: 1, 3, 5, 7, 10, 15, 20, 30, 40, 50, 60, 70, 80,
and 90%. Any of the layers of the film may have a thickness as a
percentage of the total thickness of the film of at most about any
of the following values: 90, 80, 50, 40, 35, 30, 25, 20, 15, 10,
and 5%.
[0132] A layer of the film may comprise at least about and/or at
most about any of the following amounts of dispersed-particle
composition based on the layer weight: 0.1, 0.5, 1, 3, 5, 10, 20,
50, 60, 70, 80, 90, 95, 99, and 100 weight %. A layer of the film
comprising any of the foregoing amounts of dispersed-particle
composition may also have a thickness of at least about, and/or at
most about, any of the following percentages based on the total
thickness of the film: 90, 80, 70, 60, 50, 40, 30, 20, 15, 10, and
5%.
[0133] A layer comprising the dispersed-particle composition may be
an outer layer of the film. An outer layer may be an "outside
layer" of the film (i.e., an outer layer adapted or designed to
face to the outside of a package incorporating the film) or an
"inside layer" of the film (i.e., an outer layer adapted or
designed to face the inside of a package incorporating the film).
If the film comprises only one layer, then the one layer may be
considered an "outer layer." A layer comprising the
dispersed-particle composition may be an inner or interior layer of
the film. An inner or interior layer of the film is between two
outer layers of the film.
[0134] For example, an internal tie layer of a film, such as
disclosed in U.S. patent application Ser. No. 10/452892 filed Jun.
2, 2003 by Grah et al, which is incorporated herein in its entirety
by reference, may comprise the dispersed-particle composition
discussed above.
[0135] The film comprising the dispersed-particle composition may
be formed into a package (e.g., bag or casing) for packaging (e.g.,
enclosing) an object such as a food product (e.g., coffee, nuts,
snack foods, cheese, ground or processed meat products, fresh red
meat products, and more specifically, meats such as poultry, pork,
beef, sausage, lamb, goat, horse, and fish).
[0136] The package may be formed by sealing the film to itself, or
by sealing the film to a support member (e.g., a tray, cup, or
tub), which supports the product (e.g., a food product) that may be
disposed on or in the support member. Seals may be made by adhesive
or heat sealing, such as bar, impulse, radio frequency ("RF") or
dielectric sealing. Suitable package configurations include
end-seal bag, side-seal bag, L-seal bag, pouch, and seamed casing
(e.g., back-seamed tubes by forming an overlap or fin-type seal).
Such configurations are known to those of skill in the art. The
support member (e.g., tray) may also comprise any of the
dispersed-particle compositions discussed above. The support member
may also comprise a thermoformed web comprising a
thermoplastic.
[0137] The package may also be formed by laminating or sealing the
film comprising the dispersed-particle composition to another
substrate. Suitable substrates may comprise: 1) a film comprising
one or more of the following materials: polyester (e.g., PET),
metalized polyester (e.g., metalized PET), PVdC-coated PET,
polypropylene (e.g., biaxially oriented polypropylene or BOPP),
metalized BOPP, PVdC, and coated BOPP, 2) paper, 3) paperboard, and
4) metal foil. A composite packaging structure may also be formed
by extrusion coating of one or more polymer layers, any or all of
which may comprise the dispersed-particle composition, to any of
the above substrates.
[0138] Also by way of example, once a film comprising the
dispersed-particle composition has been placed in a tube or casing
configuration, one end of the tube may be closed by tying, clipping
(e.g., metal clips), or sealing. The tube may then be filled
through the remaining open end with an uncooked food product (e.g.,
a sausage emulsion or another flowable meat product). The remaining
open end may then be closed by tying, clipping, or sealing to form
a package enclosing a food product. This filling procedure may take
place, for example, by vertical form-fill-seal or horizontal
form-fill-seal processes known to those of skill in the art.
[0139] The packaged food product enclosed within the package
comprising the film comprising the dispersed-particle composition
may be processed (e.g., cooked, retorted, or pasteurized) for
example, by immersing the packaged food in a liquid hot water bath,
exposing the packaged food to steam, or exposing the packaged food
to hot air, for an effective amount of time and at an effective
temperature and pressure. This exposure may also shrink the package
tightly about the enclosed food product by heat shrinking the film.
The packaged food may also be exposed to an amount of radiation
such as microwave radiation effective to cook the packaged food.
After the food product has been processed (e.g., cooked or
retorted) to a desired level, the packaged food may be sold in the
packaged form, or the package may be stripped from the cooked food
so the food may be processed further or consumed.
[0140] A film comprising the dispersed-particle composition may be
manufactured by thermoplastic film-forming processes known in the
art. The film may be prepared by extrusion or coextrusion
utilizing, for example, a tubular trapped bubble film process or a
flat film (i.e., cast film or slit die) process. The film may also
be prepared by extrusion coating. Alternatively, the film may be
prepared by adhesively or extrusion laminating the various layers.
These processes are known to those of skill in the art. A
combination of these processes may also be employed.
[0141] A film comprising the dispersed-particle composition may be
non-oriented. Alternatively, a film comprising the
dispersed-particle composition may be oriented in either the
machine (i.e., longitudinal), the transverse direction, or in both
directions (i.e., biaxially oriented), in order to reduce the
permeability and/or to enhance the strength, optics, and durability
of the film. The orientation of the film may also enhance the
orientation of the silicate platelets of the dispersed-particle
composition, so that generally the major plane through the
platelets is substantially parallel to the major plane through the
film. The film may be oriented in at least one direction by at
least about any of the following ratios: 2.5:1, 3:1, 3.5:1, and
3.7:1; and/or by at most about 10:1.
[0142] A film comprising the dispersed-particle composition may be
non-heat shrinkable--for example, having a free shrink in any
direction at 185.degree. F. (85.degree. C.) of less than about any
of the following: 4%, 3%, 1%, and 0.5%. A film comprising the
dispersed-particle composition may be heat shrinkable (i.e., has a
shrink characteristic), which as used herein, means that the film
has a free shrink at 185.degree. F. (85.degree. C.) in at least one
direction of at least about 5% at 185.degree. F. For example, film
comprising the dispersed-particle composition may have a free
shrink at 185.degree. F. (85.degree. C.) in either of the machine
or transverse directions (or both directions) of at least about,
and/or at most about, any of the following: 7%, 10%, 15%, 25%, 30%,
40%, 45%, 50%, 55%, 60%, 70%, and 80%. Further, the film may have
any of the preceding free shrink values measured at a temperature
selected from any of 200.degree. F., 220.degree. F., 240.degree.
F., 260.degree. F., and 280.degree. F.
[0143] The film may have unequal free shrink in both directions,
that is differing free shrink in the machine and transverse
directions. For example, the film may have a free shrink
(185.degree. F.) in the machine direction of at least 40% and a
free shrink (185.degree. F.) in the transverse direction of at
least 25%. The film may not have a heat shrink characteristic in
both directions. For example, the film may have a free shrink at
185.degree. F. in one direction of less than about any of the
following: 5%, 4%, 3%, 2% and 1%; or the film may have 0% free
shrink at 185.degree. F. in one direction. The free shrink of the
film is determined by measuring the percent dimensional change in a
10 cm.times.10 cm film specimen when subjected to selected heat
(i.e., at a specified temperature exposure) according to ASTM D
2732, which is incorporated herein in its entirety by reference.
All references to free shrink in this application are measured
according to this standard.
[0144] As is known in the art, a heat-shrinkable film shrinks upon
the application of heat while the film is in an unrestrained state.
If the film is restrained from shrinking to some extent--for
example by a packaged product around which the film shrinks--then
the tension of the heat-shrinkable film increases upon the
application of heat. Accordingly, a heat-shrinkable film that has
been exposed to heat so that at least a portion of the film is
either reduced in size (unrestrained) or under increased tension
(restrained) is considered a heat-shrunk (i.e., heat-contracted)
film.
[0145] A film comprising the dispersed-particle composition may
exhibit a shrink tension at 185.degree. F. in at least one
direction of at least about, and/or at most about, any of the
following: 100 psi, 150 psi, 175 psi, 200 psi, 225 psi, 250 psi,
275 psi, 300 psi, 325 psi, 350 psi, 400 psi, 450 psi, 500 psi, 550
psi, and 600 psi. Further, the film may have any of the preceding
shrink tensions measured at a temperature selected from any of
200.degree. F., 220.degree. F., 240.degree. F., 260.degree. F., and
280.degree. F. The film may have unequal shrink tension in both
directions, that is differing shrink tension in the machine and
transverse directions. The film may not have a shrink tension in
one or both directions. Shrink tension is measured at a specified
temperature (e.g., 185.degree. F.) in accordance with ASTM D 2838
(Procedure A), which is incorporated herein in its entirety by
reference. All references to shrink tension in this application are
by this standard.
[0146] A film comprising the dispersed-particle composition may be
annealed or heat-set to reduce the free shrink slightly,
substantially, or completely; or the film may not be heat set or
annealed once the oriented film has been quenched in order that the
film will have a high level of heat shrinkability.
Appearance Characteristics
[0147] A film comprising the dispersed-particle composition may
have low haze characteristics. Haze is a measurement of the
transmitted light scattered more than 2.5.degree. from the axis of
the incident light. Haze is measured against the outside layer of
the film. As previously discussed, the "outside layer" is the outer
layer of the film that will be adjacent the area outside of the
package comprising the film. Haze is measured according to the
method of ASTM D 1003, which is incorporated herein in its entirety
by reference. All references to "haze" values in this application
are by this standard. The haze of the film may be no more than
about any of the following values: 30%, 25%, 20%, 15%, 10%, 8%, 5%,
and 3%.
[0148] A film comprising the dispersed-particle composition may
have a gloss, as measured against the outside layer of at least
about any of the following values: 40%, 50%, 60%, 63%, 65%, 70%,
75%, 80%, 85%, 90%, and 95%. These percentages represent the ratio
of light reflected from the sample to the original amount of light
striking the sample at the designated angle. All references to
"gloss" values in this application are in accordance with ASTM D
2457 (60.degree. angle), which is incorporated herein in its
entirety by reference.
[0149] A film comprising the dispersed-particle composition may be
transparent (at least in the non-printed regions) so that a
packaged article may be visible through the film. "Transparent"
means that the film transmits incident light with negligible
scattering and little absorption, enabling objects (e.g., the
packaged article or print) to be seen clearly through the film
under typical viewing conditions (i.e., the expected use conditions
of the material). The transparency (i.e., clarity) of the film may
be at least about any of the following values: 65%, 70%, 75%, 80%,
85%, and 90%, as measured in accordance with ASTM DI 746.
[0150] The measurement of optical properties of plastic films,
including the measurement of total transmission, haze, clarity, and
gloss, is discussed in detail in Pike, LeRoy, "Optical Properties
of Packaging Materials," Journal of Plastic Film & Sheeting,
vol. 9, no. 3, pp. 173-80 (July 1993), of which pages 173-80 is
incorporated herein by reference.
[0151] The following examples are presented for the purpose of
further illustrating and explaining the present invention and are
not to be taken as limiting in any regard. Unless otherwise
indicated, all parts and percentages are by weight.
EXAMPLE 1
[0152] 10.0 grams of montmorillonite (Cloisite Na+, Southern Clay
Products) was mixed with 10 grams of water in a standard Coors
mortar to form a clay/water slurry at room temperature. 3.83 grams
(95 meq/100 g clay) of the intercalating agent pentaerythritol
monostearate (PEMS) from Oleon Corporation under the Radiasurf 7174
trademark was heated to 100.degree. C. using a double boiler and
then added to the slurry. The resulting mixture was hand compounded
in the mortar for 10 minutes at room temperature to form an
intercalated layered silicate, namely, a PEMS intercalated
montmorillonite clay. The intercalated layered silicate was dried
in an 80.degree. C. oven overnight, ground, and sieved through a
325 mesh screen to a fine powder.
[0153] The average interlayer spacing (i.e., the basal d-spacing)
of the resulting intercalated layered silicate (i.e., PEMS
intercalated clay) was determined using a BEDE D1 X-ray
diffractometer. A representative sample of the PEMS intercalated
clay was set upon a fritted glass slide for scanning by the
diffractometer, which was operated in the powder diffraction mode
using a copper X-ray source (X-ray wave-length 0.154 nm) and a
sweep of 0.5 to 20 2Theta-Omega. The interlayer spacing was
calculated using Bragg's Law, n.lamda.=2*d sin .theta., where
"n"=the order of the diffraction peak, ".lamda."=the wavelength,
"d"=the interlayer spacing (i.e., the basal d-spacing), and
".theta."=the scattering angle. The diffraction pattern for the
PEMS intercalated clay is shown in FIG. 1. The pattern indicated a
diffraction peak or shoulder at a 2.theta. of from 1.22.degree. to
1.30.degree., which calculates to an average interlayer spacing of
the layered silicate (i.e., the primary basal d-spacing) of from 68
to 72 .ANG..
[0154] FIG. 2 shows the diffraction pattern for the
non-intercalated montmorillonite clay. The pattern indicated a
diffraction peak at a 2.theta. of 7.42.degree., which calculates to
an average interlayer spacing (i.e., the primary basal d-spacing)
for the montmorillonite clay before intercalation of 11.9 .ANG.,
measured and calculated as set forth above. Accordingly, the
inclusion of the PEMS intercalating agent between the silicate
layers of the montmorillonite increased the average interlayer
spacing of the silicate layers by from about 56.1 to about 60.1
.ANG..
[0155] Thermogravimetric analysis (TGA) was obtained for the
Example 1 PEMS intercalated montmorillonite clay and the Cloisite
20A intercalated clay describe below as Comparative Sample 1. The
TGA equipment used was a TGA Q50 model available from TA
Instruments, Inc. operating at a 20.degree. C. per minute scan rate
from room temperature to 800.degree. C. in an argon purged
atmosphere. FIG. 8 shows the TGA results for the primary and first
derivative of weight loss for the Example 1 PEMS intercalated
montmorillonite. FIG. 9 shows the TGA results for the primary and
first derivative weight loss for the Comparative Sample 1. The peak
degradation temperature of the Example 1 PEMS intercalated
montmorillonite was 399.94.degree. C., which is about 87.degree. C.
higher than the 312.92.degree. C. peak degradation temperature of
the Comparison Sample 1 intercalated montmorillonite. Further, the
onset temperature of degradation for the Example 1 PEMS
intercalated montmorillonite was approximately 50.degree. C. higher
than for the Comparison Sample 1.
EXAMPLE 2
[0156] 250 grams of montmorillonite (Cloisite Na+, Southern Clay
Products) was mixed with 100 grams of water in a Hobart mixing bowl
at room temperature to form a clay/water slurry. 95.75 grams of the
intercalating agent pentaerythritol monostearate (PEMS) was heated
to 40.degree. C. and then added to the slurry. The resulting
mixture was compounded using a Hobart auger extruder at room
temperature for 30 minutes and with a rotor rotation speed of 200
rpm to form an intercalated layered silicate, namely, a PEMS
intercalated montmorillonite clay. The intercalated clay was dried
in an 80.degree. C. oven overnight, ground, and sieved through a
325 mesh screen to yield a fine powder of the PEMS intercalated
montmorillonite.
Comparative Sample 1
[0157] A commercially available dimethyl didehydrogenated tallow
quaternary ammonium intercalated montmorillonite (Cloisite 20A) was
obtained from Southern Clay Products. The concentration of the
intercalating agent was 95 meq/100 g clay. The average interlayer
spacing of the intercalated clay was determined as described above
with respect to Example 1. The diffraction pattern for Cloisite 20A
is shown in FIG. 3. The pattern indicated a diffraction peak at a
2.theta. of 3.65.degree., which calculated to an average interlayer
spacing of the layered silicate of 24.2 .ANG..
EXAMPLE 3
[0158] The PEMS intercalated clay of Example 1 was mixed with a
matrix medium of linear low density polyethylene (LLDPE) from the
Dow Corporation under the Dowlex 2045 trade name. The ratio of the
mixture was 5 weight % PEMS intercalated clay to 95 weight % LLDPE
matrix medium. The mixture was compounded for 45 minutes at
145.degree. C. using a Haake Rheomix 600 Bowl Mixer operating at 55
rpm mixer speed to form the Example 3 dispersed-particle
composition. The resulting dispersed-particle composition was
pressed on a Carver press between two glass plates into a
transparent film having a thickness varying from 40 to 100
microns.
[0159] A wide angle X-ray diffraction pattern was obtained for the
Example 3 dispersed-particle composition using the method described
above with respect to Example 1 and is shown in FIG. 4. The results
indicated that the intercalated layered silicate was substantially
exfoliated because the peak or shoulder corresponding to the
d-spacing for clay intercalated with PEMS was absent, and the film
was substantially transparent.
EXAMPLE 4
[0160] The PEMS intercalated clay of Example 1 was mixed with a
matrix medium of isotactic polypropylene from ExxonMobil
Corporation under the Escorene PP-4292 tradename. The ratio of the
mixture was 5 weight % PEMS intercalated clay to 95 weight %
polypropylene matrix medium. The mixture was compounded for 45
minutes at 170.degree. C. using a Haake Rheomix 600 Bowl Mixer
operating at 50 rpm mixer speed to form the Example 4
dispersed-particle composition. The resulting dispersed-particle
composition was pressed on a Carver press between two glass plates
into a transparent film having a thickness varying from 40 to 100
microns.
[0161] A wide angle X-ray diffraction pattern was obtained for the
Example 4 dispersed-particle composition using the method described
above with respect to Example 1 and is shown in FIG. 5. The results
indicated that the intercalated layered silicate was substantially
exfoliated because the peak or shoulder at a 2.theta. of from
1.22.degree. to 1.30.degree. corresponding to the d-spacing for
clay intercalated with PEMS was absent, and the film was
substantially transparent.
EXAMPLE 5
[0162] The PEMS intercalated clay of Example 1 was mixed with a
matrix medium of ethylene/vinyl acetate copolymer (EVA) having 28
weight % vinyl acetate content from Exxon Chemical Corporation
under the Escorene LD-761 tradename. The ratio of the mixture was 5
weight % PEMS intercalated clay to 95 weight % EVA matrix medium.
The mixture was compounded for 45 minutes at 155.degree. C. using a
Haake Rheomix 600 Bowl Mixer-operating at 60 rpm mixer speed to
form the Example 5 dispersed-particle composition. The resulting
dispersed-particle composition was pressed on a Carver press
between two glass plates into a transparent film having a thickness
varying from 40 to 100 microns.
[0163] A wide angle X-ray diffraction pattern was obtained for the
Example 5 dispersed-particle composition using the method described
above with respect to Example 1 and is shown in FIG. 6. The results
indicated that the intercalated layered silicate was substantially
exfoliated because the peak or shoulder at a 2.theta. of from
1.22.degree. to 1.30.degree. corresponding to the d-spacing for
clay intercalated with PEMS was absent, and the film was
substantially transparent. It is hypothesized that the 2.theta.
peak at about 6.degree. may indicate that some non-intercalated
layered silicate might have been present, perhaps because the sheer
of the mixing and/or the reactivity of the matrix medium may have
degraded some of the PEMS intercalating agent to allow collapse of
some silicate layers together.
EXAMPLE 6
[0164] The PEMS intercalated clay of Example 1 was mixed with a
matrix medium of nylon-6 polymer (PA6) from BASF Corporation under
the Ultramid B35 tradename. The ratio of the mixture was 5 weight %
PEMS intercalated clay to 95 weight % PA6 matrix medium. The
mixture was compounded for 45 minutes at 210.degree. C. using a
Haake Rheomix 600 Bowl Mixer operating at 50 rpm mixer speed to
form the Example 6 dispersed-particle composition. The resulting
dispersed-particle composition was pressed on a Carver press
between two glass plates into a transparent film having a thickness
varying from 40 to 100 microns.
[0165] A wide angle X-ray diffraction pattern was obtained for the
Example 6 dispersed-particle composition using the method described
above with respect to Example 1 and is shown in FIG. 7. The results
indicated that the intercalated layered silicate was substantially
exfoliated because the peak or shoulder at a 2.theta. of from
1.22.degree. to 1.30.degree. corresponding to the d-spacing for
clay intercalated with PEMS was absent, and the film was
substantially transparent.
[0166] Any numerical value ranges recited herein include all values
from the lower value to the upper value in increments of one unit
provided that there is a separation of at least 2 units between any
lower value and any higher value. As an example, if it is stated
that the amount of a component or a value of a process variable
(e.g., temperature, pressure, time) may range from any of 1 to 90,
20 to 80, or 30 to 70, or be any of at least 1, 20, or 30 and/or at
most 90, 80, or 70, then it is intended that values such as 15 to
85, 22 to 68, 43 to 51, and 30 to 32, as well as at least 15, at
least 22, and at most 32, are expressly enumerated in this
specification. For values that are less than one, one unit is
considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These
are only examples of what is specifically intended and all possible
combinations of numerical values between the lowest value and the
highest value enumerated are to be considered to be expressly
stated in this application in a similar manner.
[0167] The above descriptions are those of preferred embodiments of
the invention. Various alterations and changes can be made without
departing from the spirit and broader aspects of the invention as
defined in the claims, which are to be interpreted in accordance
with the principles of patent law, including the doctrine of
equivalents. Except in the claims and the specific examples, or
where otherwise expressly indicated, all numerical quantities in
this description indicating amounts of material, reaction
conditions, use conditions, molecular weights, and/or number of
carbon atoms, and the like, are to be understood as modified by the
word "about" in describing the broadest scope of the invention. Any
reference to an item in the disclosure or to an element in the
claim in the singular using the articles "a," "an," "the," or
"said" is not to be construed as limiting the item or element to
the singular unless expressly so stated. The definitions and
disclosures set forth in the present Application control over any
inconsistent definitions and disclosures that may exist in an
incorporated reference. All references to ASTM tests are to the
most recent, currently approved, and published version of the ASTM
test identified, as of the priority filing date of this
application. Each such published ASTM test method is incorporated
herein in its entirety by this reference.
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