U.S. patent application number 14/167719 was filed with the patent office on 2014-07-17 for blow molding polystyrene nanocomposites.
This patent application is currently assigned to FINA TECHNOLOGY, INC.. The applicant listed for this patent is FINA TECHNOLOGY, INC.. Invention is credited to Juan Aguirre, Ted Harris, Mark Leland, Jose Sosa, Luyi Sun.
Application Number | 20140200293 14/167719 |
Document ID | / |
Family ID | 43497554 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140200293 |
Kind Code |
A1 |
Sun; Luyi ; et al. |
July 17, 2014 |
BLOW MOLDING POLYSTYRENE NANOCOMPOSITES
Abstract
Disclosed is a polystyrene based polymer/layered compound
nanocomposite for injection blow molding or injection stretch blow
molding of articles. The nanocomposite can reduce shrinkage and
warpage to the preform during the reheating process compared to
neat polystyrene. The incorporation of layered compounds can
increase the processability of PS preforms, help improve heating
efficiency, and improve bottle mechanical properties. The layered
compound can be treated with chemicals or compounds having an
affinity with the styrene monomer or polystyrene, thus producing a
treated layered compound having an affinity with the styrene
monomer or polystyrene. The monomer and the layered compound can be
combined prior to polymerization. The polymer and layered compound
can be combined by solution mixing in a solvent. The layered
compound can also be incorporated into the mixture by compounding a
polymer product with the layered compound, or the combination of
any of the above three approaches
Inventors: |
Sun; Luyi; (Pearland,
TX) ; Sosa; Jose; (Deer Park, TX) ; Aguirre;
Juan; (League City, TX) ; Leland; Mark;
(Houston, TX) ; Harris; Ted; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FINA TECHNOLOGY, INC. |
Houston |
TX |
US |
|
|
Assignee: |
FINA TECHNOLOGY, INC.
Houston
TX
|
Family ID: |
43497554 |
Appl. No.: |
14/167719 |
Filed: |
January 29, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12508598 |
Jul 24, 2009 |
8697208 |
|
|
14167719 |
|
|
|
|
Current U.S.
Class: |
524/111 ;
264/513; 428/35.7; 428/36.92; 524/261; 524/263; 524/264 |
Current CPC
Class: |
B29K 2025/00 20130101;
B29D 22/003 20130101; B29K 2105/162 20130101; C08K 9/04 20130101;
B29C 49/0005 20130101; Y10T 428/1397 20150115; B29C 49/06 20130101;
Y10T 428/1352 20150115 |
Class at
Publication: |
524/111 ;
264/513; 428/35.7; 428/36.92; 524/264; 524/261; 524/263 |
International
Class: |
C08K 9/04 20060101
C08K009/04; B29D 22/00 20060101 B29D022/00 |
Claims
1-13. (canceled)
14. A method of forming a blow molded article comprising: providing
a nanocomposite comprising a polystyrene based polymer and a
layered compound; wherein the layered compound is treated with an
organic compound to thereby form a material having an affinity with
styrene, wherein the organic compound comprises a ring structured
group or a methacrylate group selected from the group consisting of
butyl methacrylate, cyclohexane, methyl styrene, cyclopentane,
chlorotoluene, methyl methacrylate, xylene, toluene, vinyl toluene,
benzene, methylcyclohexanone, styrene, furan, chlorobenzene,
cyclohexanone, dichlorobenzene, nitrobenzene, iodobenzene,
cyclopentanone, cyclobutanedione, and combinations thereof; forming
a preform having at least one layer made from the nanocomposite;
heating the preform; and injection blow molding the preform into an
article.
15. The method of claim 14, wherein the injection blow molding
comprises injection stretch blow molding the preform into the
article.
16. The method of claim 14, wherein the layered compound comprises
natural clay, synthetic clay, sols, colloids, gels, or fumes.
17. (canceled)
18. The method of claim 14, wherein a difference between a
solubility parameter of the ring structured group or the
methacrylate group and a solubility parameter of styrene is no more
than 3.0 (MPa.sup.1/2).
19-21. (canceled)
22. The method of claim 14, wherein the heating of the preform
results in a shrinkage of less than 40% and a warpage of less than
8%.
23. The method of claim 14, wherein the layered compound improves
the preform heating efficiency and the preform reaches a
temperature at least 5.degree. F. higher than an identical preform
without the layered compound when heated under the same
conditions.
24. The method of claim 14, wherein the preform includes at least
one layer of the nanocomposite and at least one layer of
polystyrene based polymer that is not a nanocomposite.
25. An article formed by the method of claim 14.
26. A method for production of a blow molded article having
improved morphology, processability, heating efficiency, and
article properties comprising: mixing polystyrene based polymer
with a treated layered compound to form a polymeric nanocomposite;
forming a preform having at least one layer made from the polymeric
nanocomposite; heating the preform to a first temperature
sufficient for blow molding the preform; injection stretch blow
molding the preform into an article; wherein the treated layered
compound has been formed by treating a layered compound with an
organic compound to produce the treated layered compound having an
affinity with the polystyrene based polymer prior to mixing;
wherein the organic compound comprises a ring structured group or a
methacrylate group selected from the group consisting of butyl
methacrylate, cyclohexane, methyl styrene, cyclopentane,
chlorotoluene, methyl methacrylate, xylene, toluene, vinyl toluene,
benzene, methylcyclohexanone, styrene, furan, chlorobenzene,
cyclohexanone, dichlorobenzene, nitrobenzene, iodobenzene,
cyclopentanone, cyclobutanedione, and combinations thereof; wherein
the layered compound improves the preform heating efficiency and
the first temperature is at least 5.degree. F. higher than the
temperature of an identical preform without the layered compound
when heated under the same conditions; wherein the heating of the
preform results in a shrinkage of less than 40% and a warpage of
less than 8%.
27. The method of claim 26, wherein the mixing comprises at least
one of the processes of: compounding the polystyrene based polymer
and the treated layered compound; solution mixing the polystyrene
based polymer and the treated layered compound in a solvent; or
mixing the treated layered compound with a styrene based monomer
prior to polymerization.
28. The method of claim 14, wherein the organic compound comprises
a ring structured group or a methacrylate group selected from the
group consisting of: butyl methacrylate, cyclohexane, methyl
styrene, cyclopentane, chlorotoluene, xylene, toluene, vinyl
toluene, benzene, methylcyclohexanone, styrene, furan,
chlorobenzene, cyclohexanone, dichlorobenzene, nitrobenzene,
iodobenzene, cyclopentanone, cyclobutanedione, and combinations
thereof.
29. The method of claim 14, wherein the organic compound comprises
a ring structured group or a methacrylate group selected from the
group consisting of: cyclohexane, methyl styrene, cyclopentane,
chlorotoluene, methyl methacrylate, xylene, toluene, vinyl toluene,
benzene, methylcyclohexanone, styrene, furan, chlorobenzene,
cyclohexanone, dichlorobenzene, nitrobenzene, iodobenzene,
cyclopentanone, cyclobutanedione, and combinations thereof.
30. The method of claim 14, wherein the organic compound comprises
a ring structured group or a methacrylate group selected from the
group consisting of: cyclohexane, methyl styrene, cyclopentane,
chlorotoluene, xylene, toluene, vinyl toluene, benzene,
methylcyclohexanone, styrene, furan, chlorobenzene, cyclohexanone,
dichlorobenzene, nitrobenzene, iodobenzene, cyclopentanone,
cyclobutanedione, and combinations thereof.
31. The method of claim 14, wherein the layered compound comprises
an organoclay.
32. The method of claim 14, wherein the polystyrene based polymer
comprises a homopolymer or a styrenic polymer with one or more
comonomers, and wherein the polystyrene based polymer is present in
the nanocomposite in an amount of from 90 wt. % to 99.5 wt. % based
on the total weight of the nanocomposite.
33. The method of claim 14, wherein the polystyrene based polymer
further comprises an elastomeric phase that is embedded in a
polymer matrix, wherein the elastomeric phase is selected from one
or more of a conjugated diene monomer, an aliphatic conjugated
diene monomer, and blends or copolymers of the diene monomers, and
wherein the elastomeric phase is present in the polystyrene based
polymer in an amount ranging from 0.1 wt. % to 10 wt. %.
34. The method of claim 14, wherein the injection blow molding of
the preform into the article comprises a co-injection blow molding
process.
35. The method of claim 14, wherein the injection blow molding of
the preform into the article comprises a single or double stage
injection blow molding process.
36. A preform useful in blow molding processes comprising: a
nanocomposite comprising a polystyrene based polymer and a layered
compound; wherein the layered compound is treated with an organic
compound to thereby form a material having an affinity with
styrene; and wherein the organic compound comprises a ring
structured group or a methacrylate group selected from the group
consisting of butyl methacrylate, cyclohexane, methyl styrene,
cyclopentane, chlorotoluene, methyl methacrylate, xylene, toluene,
vinyl toluene, benzene, methylcyclohexanone, styrene, furan,
chlorobenzene, cyclohexanone, dichlorobenzene, nitrobenzene,
iodobenzene, cyclopentanone, cyclobutanedione, and combinations
thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of U.S. application Ser.
No. 12/508,598, filed on Jul. 24, 2009.
FIELD
[0002] Embodiments of the present invention generally relate to
blow molding of polystyrene. In particular, embodiments of the
invention relate to incorporating a layered compound such as clay
nanoplatelets into the polystyrene for injection stretch blow
molding and injection blow molding of styrene based polymers.
BACKGROUND
[0003] In general, a high quality packaging material is one that
creates a good oxygen and moisture barrier. Packaged goods are
intended to last longer typically by reducing their interaction
with oxygen and water, which usually can deteriorate the product
causing waste and other problems. Polymeric materials are often
used as packaging materials because they create a good
oxygen/moisture barrier and their appearance and shape can be
easily controlled. Plastic materials are also used in place of
glass for bottling because they are lighter, are more resistant to
breakage when dropped, and can be less expensive. Several common
polymeric materials used for packaging are polyethylene (PE),
polyethylene terephthalate (PET), polypropylene (PP), polycarbonate
(PC), and polystyrene (PS).
[0004] Polystyrene is one of the largest volume thermoplastic
resins in commercial production today. It is a hydrocarbon chain
containing a phenyl group on every other carbon atom. Polystyrene
is a durable polymer that is frequently encountered in daily life.
A few common examples of polystyrene are plastic toys, computer
housings, foam packaging, foam cups, etc.
[0005] Injection blow molding (IBM) and injection stretch blow
molding (ISBM) are well-developed techniques to produce plastic
containers that include the formation of a perform that is
subsequently heated and blow molded to produce a hollow container.
Preforms are generally condensed shapes, which may include
relatively thick-walled tube shaped articles having a threaded neck
to facilitate appropriate closure. The preforms can be blown into a
desired article shape by heating, stretching, and blowing the
preform with a compressed gas. The compressed gas expands the
preform into the shape of the mold.
[0006] Polymer nanocomposites comprise polymeric materials and
inorganic layered compounds, such as clay. When these inorganic
layered components are properly incorporated into a polymer matrix,
significant improvements in physical and mechanical properties can
be displayed. The extent of uniformity of the layered compound
incorporated into the polymer matrix influences the characteristics
of the nanocomposite.
[0007] A high degree of intercalation (the inserting of a molecule,
or group of molecules, between a layer of clays) and exfoliation
(the delamination of layered materials into disordered layers or
sheets) are desired in order to achieve proper incorporation of the
inorganic layered compounds into a polymer matrix. In order to
achieve a high degree of intercalation and exfoliation, the clays
can be treated by some organic chemicals to increase their surface
hydrophobicity and interlayer distances. These clays can be
referred to as organoclays.
[0008] An initial evaluation of polystyrene for blow molding
applications led to shrinkage and warpage issues. It is desirable
to have polystyrene compositions that can minimize shrinkage and
warpage during blow molding.
SUMMARY
[0009] Embodiments of the present invention include a preform for
use in blow molding processes of polystyrene based polymer. The
preform includes a neck having an internal neck diameter and an
external neck diameter, a body comprising an internal body diameter
and an external body diameter which together form a sidewall, and
is made of a nanocomposite including a polystyrene based polymer
and a layered compound.
[0010] The layered compound can be selected from the group
consisting of natural clay, synthetic clay, sols, colloids, gels,
and fumes. The layered compound can be a treated layered compound
formed by treating a layered compound with an organic compound to
produce a treated layered compound having an affinity with styrene.
The layered compound can be treated by a chemical that has an
organic group having a solubility parameter, wherein the difference
between the organic group solubility parameter and the solubility
parameter of styrene is no more than 3.0 (MPa.sup.1/2).
[0011] The layered compound can be treated by a chemical that
comprises at least one hydrocarbon ring group, or by a chemical
that comprises at least one methacrylate group. The layered
compound can be treated by a chemical that is represented by the
formula:
##STR00001##
where HT is Hydrogenated Tallow (.about.65% C.sub.18; .about.30%
C.sub.16; .about.5% C.sub.14).
[0012] The invention can include an article formed by the blow
molding of the preform described herein. The preform can have a
shrinkage of less than 38% when reheated during a blow molding
process. The preform can have a warpage of less than 8.5% when
reheated during a blow molding process.
[0013] The layered compound incorporated within the preforms can
help absorb energy, thus improving reheating efficiency. As a
result, embodiments of the invention can include preforms made of
nanocomposites that can reach a temperature of at least 5.degree.
F. higher than an identical preform without the layered compound
when reheated during a blow molding process under the same
conditions.
[0014] Embodiments of the present invention include a method of
forming a blow molded article by providing a nanocomposite
comprising a polystyrene based polymer and a layered compound,
forming a preform from the nanocomposite, heating the preform, and
injection blow molding the preform into an article. The preform has
at least one layer of the nanocomposite and can include one or more
layers of a polystyrene based polymer that is not a nanocomposite.
The injection blow molding can include injection stretch blow
molding the preform into an article. The layered compound can be
selected from the group consisting of natural clay, synthetic clay,
sols, colloids, gels, and fumes. The method can include the layered
compound being a treated layered compound formed by treating a
layered compound with an organic compound to produce a treated
layered compound having an affinity with styrene.
[0015] The layered compound can be treated by a chemical that has
an organic group having a solubility parameter, wherein the
difference between the organic group solubility parameter and the
solubility parameter of styrene is no more than 3.0 (MPa.sup.1/2).
The layered compound can be treated by a chemical that has at least
one hydrocarbon ring group. The layered compound can be treated by
a chemical that has at least one methacrylate group.
[0016] The layered compound can be treated by a chemical that is
represented by the formula:
##STR00002##
where HT is Hydrogenated Tallow (.about.65% C.sub.18; .about.30%
C.sub.16; .about.5% C.sub.14).
[0017] The method can include heating of the preform resulting in
shrinkage of less than 38% and warpage of less than 8.5%.
[0018] The layered compound incorporated within the preforms can
help absorb energy, thus improving reheating efficiency. As a
result, embodiments of the invention can include preforms made of
nanocomposites that can reach a temperature at least 5.degree. F.
higher than an identical preform without the layered compound when
heated under the same conditions. The invention can include an
article formed by the method described.
[0019] An embodiment of the present invention is a method for
production of a blow-molded article having improved morphology,
processability and heating efficiency. The method includes mixing
polystyrene based polymer with a treated layered compound to form a
polymeric nanocomposite and forming a preform from the polymeric
nanocomposite. The preform has at least one layer of the
nanocomposite and can include one or more layers of a polystyrene
based polymer that is not a nanocomposite. The preform is heated to
a first temperature sufficient for blow molding the preform and
injection stretch blow molding the preform into an article. The
treated layered compound can be formed by treating a layered
compound with an organic compound to produce a treated layered
compound having an affinity with the polystyrene based polymer
prior to mixing. The layered compound improves the preform heating
efficiency and therefore the first temperature is at least
5.degree. F. higher than the temperature of an identical preform
without the layered compound when heated under the same conditions.
The heating of the preform results in a shrinkage of less than 38%
and a warpage of less than 8.5%.
[0020] The mixing of the polymer and the treated layered compound
can include at least one of the processes of: compounding the
polymer and the treated layered compound; solution mixing the
polymer and the treated layered compound in a solvent; or mixing
the treated layered compound with a styrene based monomer prior to
polymerization.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 shows the bottom of two articles showing non-uniform
thickness and whitening (left) or blow-out (right).
[0022] FIG. 2 shows (A) a PS535/10A preform after heating to
optimum conditions for blow molding; (B) a PS535 preform after
heating under the same conditions as (A); (C) a PS535 preform after
heating to desired conditions for blow molding; and (D) a PS535
preform before heating.
[0023] FIGS. 3A and 3B shows a cross sections of a preform
illustrating shrinkage and warpage before and after heating,
respectively.
[0024] FIG. 4 represents a method of preparing a layered
compound/polymer composite involving extrusion compounding.
DETAILED DESCRIPTION
[0025] Injection blow molding (IBM) and injection stretch blow
molding (ISBM) are well-developed techniques to produce plastic
containers that include the formation of a perform that is
subsequently heated and blow molded to produce a hollow container.
Preforms are generally condensed shapes, which may include
relatively thick-walled tube shaped articles having a threaded neck
to facilitate appropriate closure. The preforms can be blown into a
desired article shape by heating, stretching, and blowing the
preform with a compressed gas. The compressed gas expands the
preform into the shape of the mold.
[0026] The injection stretch blow molding process can be either a
single or double stage process. The single stage process injects
the molten polymer into the preform mold creating the preform,
stretches the preform, and finally blows the preform into the
finished shape all in the same process. In a double stage process,
performs are injection molded at the first stage. After the
preforms are cooled down, they are reheated and subsequently
stretched/blow molded into bottles at the second stage.
[0027] Polystyrene is a material under development for blow molding
applications. An initial evaluation of polystyrene for ISBM
applications resulted in a high rejection rate and the molded
bottles exhibited inconsistent properties. Both crystal and high
impact polystyrene (HIPS) grades exhibited shrinkage and uneven
shrinkage. Moreover, the uneven shrinkage during reheating resulted
in warpage along the preform axial (off-center). Such off-centered
preforms can give rise to a non-uniform bottle bottom and poor
mechanical properties. In addition, the bottle bottom can show
signs of whitening, an undesirable characteristic for the finished
part as shown in FIG. 1. Thus, it is important to address the
shrinkage and warpage issues associated with PS ISBM process.
[0028] The incorporation of inorganic fillers, such as layered
fillers, may reduce PS chain relaxation upon reheating by
constraining the flexible chains within the stiff inorganic layers.
This effect may be enhanced if the filler is incorporated into the
matrix on a nanometer scale. Thus, clay based nanocomposites appear
to be potential candidates for improving the processing of PS in
IBM and ISBM processes.
[0029] As used herein "nanocomposites" refer to materials that are
created by introducing nanoparticles with at least one dimension
less than 100 nanometers (nm), also called filler materials (e.g.,
a layered compound) into a macroscopic material (e.g., polymeric
material), which is commonly referred to as the matrix. According
to embodiments of the invention the preform and resulting article
from blow molding the preform comprise a nanocomposite having a
layered filler material (also referred to as a nanofiller) and a
polystyrene matrix.
[0030] The layered compounds can include natural and synthetic
clay, sols, colloids, gels, fumes, and the like. In an embodiment,
the nanocomposite comprises clay. In accordance with this
disclosure, clays refer to aggregates of hydrous silicate particles
either naturally occurring or synthetically produced, and may
consist of a variety of minerals rich in silicon and aluminum
oxides and hydroxides which include variable amounts of other
components such as alkali earth metals and water. Naturally
occurring clays are usually formed by chemical weathering of
silicate-bearing rocks, although some are formed by hydrothermal
activity. These types of clays can be replicated in industrial
chemical processes. Many types of clay have sheet-like (layered)
structures and these layers are typically referred to as platelets.
These platelets have a degree of flexibility with a thickness on
the order of 1 nm and aspect ratios of 50 to 1500.
[0031] The clays used in an embodiment of the present invention can
be organophilic and such clays are typically referred to as
organoclay. Organoclay is an organically modified silicate compound
that is derived from natural or synthetic clay. Organoclay can be
produced from clays that are typically hydrophilic by ion exchange
with an organic cation. Some examples of layered materials suitable
as components in organoclays include without limitation natural or
synthetic bentonite, montmorillonite, hectorite, fluorohectorite,
saponite, stevensite, nontronite, sauconite, glauconite,
vermiculite, chlorite, mica, hydromica, muscovite, biotite,
phlogopite, illite, talc, pyrophillite, sepiolite, attapulgite,
palygorskite, berthierine, serpentine, kaolinite, dickite, nacrite,
halloysite, allophane, imogolite, hydrotalcite, pyroaurite,
calcite, wollastonite, or combinations thereof.
[0032] Examples of an organoclay suitable for use in this
disclosure include without limitation CLOISITE 10A, CLOISITE 15A,
and CLOISITE 20A, which are commercially available from Southern
Clay Products, Inc.
[0033] CLOISITE 10A has the composition that is represented by the
formula:
##STR00003##
where HT is Hydrogenated Tallow (.about.65% C.sub.18; .about.30%
C.sub.16; .about.5% C.sub.14); Anion: Chloride;
[0034] Cation exchange capacity (CEC): 125 meq/100 g clay.
[0035] CLOISITE 15A has the composition that is represented by the
formula:
##STR00004##
where HT is Hydrogenated Tallow (.about.65% C.sub.18; .about.30%
C.sub.16; .about.5% C.sub.14); Anion: Chloride; Cation exchange
capacity (CEC): 125 meq/100 g clay.
[0036] CLOISITE 20A has the composition that is represented by the
formula:
##STR00005##
where HT is Hydrogenated Tallow (.about.65% C.sub.18; .about.30%
C.sub.16; .about.5% C.sub.14); Anion: Chloride; Cation exchange
capacity (CEC): 95 meq/100 g clay.
[0037] In embodiments of the invention, the organoclay may be
present in an amount of from 0.1 weight percent (wt. %) to 50 wt.
%, alternatively from 0.5 wt. % to 25 wt. %, or from 1 wt. % to 10
wt. %.
[0038] In accordance with the invention, the nanocomposite
comprises a polystyrene based polymer. The polymer may be present
in the nanocomposite in an amount of from 50 wt. % to 99.9 wt. %,
or from 90 wt. % to 99.5 wt. %, or from 95 wt. % to 99 wt. % based
on the total weight of the nanocomposite.
[0039] In an embodiment, the polystyrene based polymer can be
formed from monomers having a phenyl group. More specifically, the
polymer can be formed from monomers having an aromatic moiety and
an unsaturated alkyl moiety. Such monomers may include
monovinylaromatic compounds such as styrene as well as alkylated
styrenes wherein the alkylated styrenes are alkylated in the
nucleus or side-chain. Alphamethyl styrene, t-butylstyrene,
p-methylstyrene, acrylic and methacrylic acids or substituted
esters of acrylic or methacrylic acid, and vinyl toluene are
suitable monomers that may be useful in forming a polystyrene based
polymer of the invention. These monomers are disclosed in U.S. Pat.
No. 7,179,873 to Reimers et al., which is incorporated by reference
in its entirety.
[0040] The polystyrene based polymer component in the nanocomposite
can be a styrenic polymer (e.g., polystyrene), wherein the styrenic
polymer may be a homopolymer or may optionally comprise one or more
comonomers. Styrene, also known as vinyl benzene, ethenylbenzene,
phenethylene and phenylethene is an aromatic organic compound
represented by the chemical formula C.sub.8H.sub.8. Styrene is
widely commercially available and as used herein the term styrene
includes a variety of substituted styrenes (e.g. alpha-methyl
styrene), ring substituted styrenes such as p-methylstyrene,
distributed styrenes such as p-t-butyl styrene as well as
unsubstituted styrenes.
[0041] In an embodiment, the styrenic polymer has a melt flow as
determined in accordance with ASTM D1238 of from 1.0 g/10 min to
30.0 g/10 min, alternatively from 1.5 g/10 min to 20.0 g/10 min,
alternatively from 2.0 g/10 min to 15.0 g/10 min; a density as
determined in accordance with ASTM D1505 of from 1.04 g/cc to 1.15
g/cm.sup.33, alternatively from 1.05 g/cm.sup.3 to 1.10 g/cc,
alternatively from 1.05 g/cm.sup.3 to 1.07 g/cm.sup.3, a Vicat
softening point as determined in accordance with ASTM D1525 of from
227.degree. F. to 180.degree. F., alternatively from 224.degree. F.
to 200.degree. F., alternatively from 220.degree. F. to 200.degree.
F.; and a tensile strength as determined in accordance with ASTM
D638 of from 5800 psi to 7800 psi. Examples of styrenic polymers
suitable for use in this disclosure include without limitation
CX5229 and PS535, which are polystyrenes available from Total
Petrochemicals USA, Inc. In an embodiment the styrenic polymer
(e.g., CX5229) has generally the properties set forth in Table
1.
TABLE-US-00001 TABLE 1 Typical Value Test Method Physical
Properties Melt Flow, 200/5.0 g/10 m 3.0 D1238 Tensile Properties
Strength, psi 7,300 D638 Modulus, psi (10.sup.5) 4.3 D638 Flexular
Properties Strength, psi 14,000 D790 Modulus, psi (10.sup.5) 4.7
D790 Thermal Properties Vicat Softening, deg. F. 223 D1525
[0042] In some embodiments, the styrenic polymer or polystyrene
based polymer further comprises a comonomer which when polymerized
with styrene forms a styrenic copolymer. Examples of such
copolymers may include for example and without limitation
.alpha.-methylstyrene; halogenated styrenes; alkylated styrenes;
acrylonitrile; esters of methacrylic acid with alcohols having 1 to
8 carbons; N-vinyl compounds such as vinylcarbazole and maleic
anhydride; compounds which contain two polymerizable double bonds
such as for example and without limitation divinylbenzene or
butanediol diacrylate; or combinations thereof. The comonomer may
be present in an amount effective to impart one or more
user-desired properties to the composition. Such effective amounts
may be determined by one of ordinary skill in the art with the aid
of this disclosure. For example, the comonomer may be present in
the styrenic polymer in an amount ranging from 0.1 wt. % to 99.9
wt. % by total weight of the nanocomposite, alternatively from 1
wt. % to 90 wt. %, and further alternatively from 1 wt. % to 50 wt.
%.
[0043] In an embodiment, the polymer or polystyrene based polymer
also comprises a thermoplastic material. Herein a thermoplastic
material refers to a plastic that melts to a liquid when heated and
freezes to form a brittle and glassy state when cooled
sufficiently. Examples of thermoplastic materials include without
limitation acrylonitrile butadiene styrene, celluloid, cellulose
acetate, ethylene vinyl acetate, ethylene vinyl alcohol,
fluoroplastics, ionomers, polyacetal, polyacrylates,
polyacrylonitrile, polyamide, polyamide-imide, polyaryletherketone,
polybutadiene, polybutylene, polybutylene terephthalate,
polychlorotrifluoroethylene, polyethylene terephthalate,
polycyclohexylene dimethylene terephthalate, polycarbonate,
polyetherimide, polyethersulfone, polyethylenechlorinate,
polyimide, polylactic acid, polymethylpentene, polyphenylene oxide,
polyphenylene sulfide, polyphthalamide, polypropylene, polysulfone,
polyvinyl chloride, polyvinylidene chloride, and combinations
thereof. For example, the thermoplastic material may be present in
the styrenic polymer in an amount ranging from 0.1 wt. % to 50 wt.
% by total weight of the nanocomposite.
[0044] In an embodiment, the polymer or polystyrene based polymer
comprises an elastomeric phase that is embedded in a polymer
matrix. For instance, the polymer may comprise a styrenic polymer
having a conjugated diene monomer as the elastomer. Examples of
suitable conjugated diene monomers include without limitation
1,3-butadiene, 2-methyl-1,3-butadiene, and 2-chloro-1,3-butadiene.
Alternatively, the thermoplastic may comprise a styrenic polymer
having an aliphatic conjugated diene monomer as the elastomer.
Without limitation, examples of suitable aliphatic conjugated diene
monomers include C.sub.4 to C.sub.9 dienes such as butadiene
monomers. Blends or copolymers of the diene monomers may also be
used. Examples of thermoplastic polymers include without limitation
acrylonitrile butadiene styrene (ABS), high impact polystyrene
(HIPS), methyl methacrylate butadiene (MBS), and the like. The
elastomer may be present in an amount effective to impart one or
more user-desired properties to the composition. Such effective
amounts may be determined by one of ordinary skill in the art with
the aid of this disclosure. For example, the elastomer may be
present in the styrenic polymer in an amount ranging from 0.1 wt. %
to 50 wt. % by total weight of the nanocomposite, or from 1 wt. %
to 25 wt. %, or from 1 wt. % to 10 wt. %.
[0045] In accordance with the invention, the nanocomposite also
optionally comprises additives, as deemed necessary to impart
desired physical properties. The additives used in the invention
may be additives having different polarities. Additives suitable
for use in the invention include without limitation zinc
dimethacrylate, hereinafter referred to as "ZnDMA", stearyl
methacrylate, hereinafter referred to as "StMMA", and
hydroxyethylmethacrylate, hereinafter referred to as "HEMA".
[0046] These additives may be included in amounts effective to
impart desired physical properties. In an embodiment, the
additive(s) are included in amounts of from 0.01 wt. % to 10 wt. %.
In another embodiment, when ZnDMA is the additive, it is present in
amounts of from 0.01 wt. % to 5 wt. %. In another embodiment, when
the additive is StMMA or HEMA, the additive is present in amounts
of from 1 wt. % to 10 wt. %.
[0047] The chemically treated clay, CLOISITE 10A, has an affinity
with styrene monomers and can exhibit a high degree of exfoliation
when added to styrene, as disclosed in U.S. patent application Ser.
No. 12/365,113, incorporated herein in its entirety. CLOISITE 10A,
having a benzyl group attached to it, exhibits high affinity with
the benzyl structure of styrene. CLOISITE 10A was found to have
more structures having a higher degree of exfoliation within a
sample of nanocomposite comprising styrene polymer than organoclays
not having a benzyl group. Other organoclays having hydrocarbon
ring structures can have an affinity to a styrenic based monomer
and can be desirable for use in the present invention. Organoclays
having methacrylate groups attached can also provide an affinity to
styrenic based monomers.
[0048] As used herein two materials have an affinity for each other
if there is no more than 3.0 (MPa.sup.1/2) difference between their
solubility parameters. CLOISITE 10A contains a benzyl group,
benzene having a solubility parameter of 18.8 (MPa.sup.1/2) while
styrene has a solubility parameter of 19.0 (MPa.sup.1/2). The
addition of the organic compound to the clay, in this instance the
benzyl group, provides an affinity between the clay and the
polymer, as the solubility parameter of the benzyl group is close
to that of the styrene. Other hydrocarbon ring structures have
solubility parameters that would impart an affinity for styrene,
such as cyclohexane with a solubility parameter of 16.8
(MPa.sup.1/2), cyclopentane with a solubility parameter of 17.8
(MPa.sup.1/2), and cyclopentanone with a solubility parameter of
21.3 (MPa.sup.1/2).
[0049] As non-limiting examples, Table 2 provides a list of various
ring structured groups and methacrylate groups that may be used to
modify a layered compound to provide an affinity between the
layered compound and the monomer or polymer that the layered
compound is being dispersed into. Data in Table 2 is taken from the
Polymer Handbook, 4th edition by J. Brandrup, E. H. Immergut, and
E. A Grulke, John Wiley & Sons, Inc., 1999. The solubility
parameter can be changed via copolymerization and solubility
parameters for different structures can be calculated via the
techniques given in the Polymer Handbook and published by P. A.
Small [J. Applied Chemistry, Vol. 3, p. 71 (1953)] by using
molar-attraction constants.
TABLE-US-00002 TABLE 2 Solvent Solubility Parameter (MPa.sup.1/2)
Butyl methacrylate 16.8 Cyclohexane 16.8 Ethyl methacrylate 17.0
Methyl styrene 17.4 Cyclopentane 17.8 Chlorotoluene 18.0
Ethylbenzene 18.0 Methyl methacrylate 18.0 Xylene (p-xylene) 18.0
Toluene 18.2 Vinyl toluene 18.6 Benzene 18.8 Methylcyclohexanone
19.0 Styrene 19.0 Furan 19.2 Chlorobenzene 19.4 Cyclohexanone 20.3
Dichlorobenzene 20.5 Nitrobenzene 20.5 Iodobenzene 20.7
Cyclopentanone 21.2 Cyclobutanedione 22.5
[0050] In an embodiment, a method for production of the styrenic
polymer comprises contacting styrene monomer and other components
under proper polymerization reaction conditions. The polymerization
process may be operated under batch or continuous process
conditions. In an embodiment, the polymerization reaction may be
carried out using a continuous production process in a
polymerization apparatus comprising a single reactor or a plurality
of reactors. In an embodiment of the invention, the polymeric
composition can be prepared for an upflow reactor. Reactors and
conditions for the production of a polymeric composition are
disclosed in U.S. Pat. No. 4,777,210, to Sosa et al., which is
incorporated by reference in its entirety.
[0051] The operating conditions, including temperature ranges, can
be selected in order to be consistent with the operational
characteristics of the equipment used in the polymerization
process. In an embodiment, polymerization temperatures range from
190.degree. F. to 460.degree. F. In another embodiment,
polymerization temperatures range from 200.degree. F. to
360.degree. F. In yet another embodiment, the polymerization
reaction may be carried out in a plurality of reactors, wherein
each reactor is operated under an optimum temperature range. For
example, the polymerization reaction may be carried out in a
reactor system employing first and second polymerization reactors
that are either both continuously stirred tank reactors (CSTR) or
both plug-flow reactors or one reactor a CSTR and the other a
plug-flow reactor. In an embodiment, a polymerization reactor for
the production of a styrenic copolymer of the type disclosed herein
may comprise a plurality of reactors wherein the first reactor
(e.g., a CSTR), also known as the prepolymerization reactor, is
operated in the temperature range of from 190.degree. F. to
275.degree. F. while the second reactor (e.g., CSTR or plug flow)
may be operated in the range of 200.degree. F. to 330.degree.
F.
[0052] The polymerized product effluent may be referred to herein
as the prepolymer. When the prepolymer reaches a desired
conversion, it may be passed through a heating device into a second
reactor to achieve further polymerization. The polymerized product
effluent from the second reactor may be further processed as
desired or needed. Upon completion of the polymerization reaction,
a styrenic polymer is recovered and subsequently processed, for
example devolatized, pelletized, etc.
[0053] In accordance with the invention, the layered compound may
be incorporated into the polymer/monomer at any stage of the
polymerization process, for example, including without limitation
before, during, or after the polymerization process. In an
embodiment, the layered compound is incorporated by mixing of a
monomer with the layered compound. For example, by the mixing of
styrene monomer with organoclay prior to in situ polymerization. In
another embodiment, the layered compound is incorporated by
compounding the polymerized product with a layered compound. For
example, compounding polystyrene with an organoclay. In yet another
embodiment, the layered compound is incorporated by solution mixing
with a polymer, such as polystyrene, in a proper solvent, such as
toluene or tetrahydrofuran. For example, solution mixing
polystyrene with an organoclay in toluene.
[0054] In an embodiment the layered compound is compounded with a
polymer. In such an embodiment, in reference to FIG. 5, the method
100 may initiate by contacting the polymer 110 and a layered
compound 120 to form a mixture via extrusion compounding 130.
Extrusion compounding 130 refers to the process of mixing a polymer
with one or more additional components wherein the mixing may be
carried out using a continuous mixer such as for example a mixer
consisting of a short non-intermeshing counter rotating twin screw
extruder or a gear pump for pumping.
[0055] In another embodiment, the polymerized product resulting
from in situ polymerization of a monomer with a layered compound is
subjected to extrusion compounding 130 to achieve further
exfoliation and dispersion of the layered compound. In yet another
embodiment, the nanocomposite product resulting from a mixed
solution comprising polystyrene and a layered compound, which is
dried after solution mixing, can be subjected to extrusion
compounding 130 to achieve further exfoliation and dispersion of
the layered compound.
[0056] Extrusion compounding 130 may produce a composition in which
some of the polymer has been intercalated into the layered compound
as depicted in structure 140a. In structure 140a, the polymer 110
is inserted between platelets of the layered compound 120 such that
the interlayer spacing of the layered compound 120 is expanded but
still possess a well-defined spatial relationship with respect to
each other. Extrusion compounding 130 may also result in some
degree of exfoliation as shown in 140b in which the platelets of
the layered compound 120 have been separated and the individual
layers are distributed throughout the polymer 110. The mixture of
layered compound and polymer after having been extrusion compounded
is hereinafter referred to as the extruded mixture 140a,b.
[0057] The method 100 can also include further processing 150 of
the extruded mixture 140a,b, such as by imparting shear stresses or
orientation forces. The further processing 150 can result in
increased exfoliation of the resulting product 160a,b, where the
platelets of the layered compound 120 have been further separated
and the individual layers are distributed throughout the polymer
110 providing an intercalated/exfoliated morphology. Although 140b
may have a higher degree of exfoliation than 140a, depending on the
extent and effectiveness of the further processing 150, 160b may or
may not have a higher degree of exfoliation than 160a.
[0058] As disclosed in U.S. patent application Ser. No. 12/365,113,
an article constructed from a nanocomposite containing a layered
compound with the polymer/monomer showed an improvement in both
flexural modulus and Young's modulus, compared to the polymer
lacking the layered compound. Young's modulus is a measure of the
stiffness of a material and is defined as the ratio of the rate of
change of stress with strain. Young's modulus can be determined
experimentally from the slope of a stress-strain curve created
during tensile tests conducted on a sample of a material, as
determined in accordance with ASTM D882. In an embodiment, the
article made from the nanocomposite may exhibit an increase in
Young's modulus at yield when compared to a similar article
constructed from a polymer lacking the layered compounds of from 5%
to 300%, alternatively from 10% to 100%, alternatively from 20% to
50%. The flexural modulus is another measure of the stiffness of a
material and is defined as the amount of applied force over the
amount of deflected distance. The flexural modulus is measured in
accordance with ASTM D790. In an embodiment, the article made from
the nanocomposite may exhibit an increase in flexural modulus when
compared to a similar article constructed from a polymer lacking
the layered compounds of from 5% to 300%, alternatively from 10% to
100%, alternatively from 20% to 50%. In another embodiment, the
article made from nanocomposite may exhibit an increase in tensile
strength at yield, as determined in accordance with ASTM D882, when
compared to a similar article constructed from a polymer that does
not contain the layered compounds of from 5% to 300%, alternatively
from 10% to 100%, alternatively from 20% to 50%.
[0059] The optical properties of the nanocomposite containing a
layered compound are dependent upon the degree of dispersion of the
layered compound. When the layered compound is well exfoliated and
uniformly dispersed, the negative optical effect of the layered
compound is minimal. Conversely, poor dispersion of the layered
compound in the nanocomposite leads to a significant drop in the
clarity of the nanocomposite and the articles made from the
nanocomposite. Nanocomposites containing organoclays having an
increased affinity with the styrenic polymer lead to greater
exfoliation and are more uniformly dispersed, thereby providing
better optical properties.
EXAMPLE
[0060] In order to evaluate the effects of the clay based
nanocomposites, a PS nanocomposite made from commercially available
polystyrene PS535 from Total Petrochemicals, Inc. was mixed with 5
wt % of CLOISITE 10A, an organoclay commercially available from
Southern Clay Products, Inc., herein referred to as 535/10A. The
535/10A mixture was compounded using a twin-screw extruder and was
molded into preforms on a Netstal injection molder. The preforms
were conditioned at room temperature for at least 24 hours before
they were stretch-blow-molded into bottles on an ADS G62 linear
injection stretch blow molder.
[0061] In the ISBM process, the 535/10A preforms exhibited lower
shrinkage, and limited warpage, as compared to preforms of neat
PS535. Thus, the preforms were successfully blow molded into
bottles at the four conditions shown below in Table 3.
TABLE-US-00003 TABLE 3 Summary of processing conditions of PS535
and 535/10A preforms. Oven 10 Oven 10 Temperature before and 20,
and 20, Oven 20 Oven 20 blow molding (Oven Preform 2000 b/h 3000
b/h only, 2000 b/h only, 3000 b/h 10 and 20, 2000 b/h) PS535 ~50%
rejection rate, significant Not 260.degree. F. whitening on the
bottom enough heat 535/10A <2% rejection rate, with few
whitening signs on 246.degree. F. (5 wt %) the bottom
[0062] FIG. 3A shows a cross section view of a preform before
heating, and FIG. 3B shows a cross section view of a preform after
heating. The first preform length (H.sub.1) and the first body
length (h.sub.1) are shown in FIG. 3A. The preform length after
heating (H.sub.2), body length after heating (h.sub.2) and amount
of deviation (d) are shown in FIG. 3B. Shrinkage is defined as
(h.sub.1-h.sub.2)/h.sub.1 and warpage is defined as d/h.sub.2.
[0063] FIG. 2 shows (A) a PS535/10A preform after heating to its
optimum conditions for blow molding; (B) a PS535 preform after
heating under the same conditions as (A); (C) a PS535 preform after
heating to its desired conditions for blow molding; and (D) a PS535
preform before heating. The shrinkage of the PS535/10A preform,
shown as A, is approximately 20% and the warpage is virtually zero
after heated at its optimized condition, while the shrinkage and
warpage of the PS535 preform, shown as C, is about 40% and 8%,
respectively, after heated at its optimized condition. The
nanocomposite (A) exhibited significantly reduced shrinkage and
warpage than the neat PS(C) at processing conditions. The
nanocomposite required less heating to achieve processing
conditions. The PS535 preform (B), subjected to the same heating
conditions as the nanocomposite (A), did not absorb the heat as
well as the nanocomposite and did not have sufficient heat to
achieve blow molding conditions.
TABLE-US-00004 TABLE 4 Preform A B C Temp (.degree. F.) 246 218 260
Shrinkage 20 8 40 (%) Warpage 0 0 8 (%)
[0064] In addition, it was observed that 535/10A preforms can be
blow molded into bottles with less heat compared to neat PS535
preforms. For comparison, both PS535, shown as C in FIG. 2, and
535/10A, shown as A in FIG. 2, preforms were reheated at their
optimized conditions and a measurement of the surface temperature
was made with an IR thermometer as they exited the oven. The
535/10A, shown as A had a temperature of 246.degree. F. while the
PS535 preform shown as C in FIG. 2 had a temperature of 260.degree.
F. The PS535 preform was also reheated at the optimized condition
for 535/10A and then tested for surface temperature and had a
temperature of 218.degree. F., which is shown as B. At the same
heating profile (optimized for 535/10A), the surface temperature of
535/10A preform is 28.degree. F. higher than the PS535 preform. At
the same time, in order to optimize the heating for the PS535
preforms, they had to be heated to 260.degree. F., which is
14.degree. F. higher than 535/10A preforms.
[0065] The 535/10A preforms were successfully blow molded into
bottles at a production rate of 3000 b/h. However, the same ADS G62
linear injection stretch blow molder failed to blow mold PS535
preforms at the same conditions owing to a limited heating
capacity. The incorporation of clay nanoplatelets into the
polystyrene matrix is shown to be able to improve both
processability and heating efficiency.
[0066] The incorporation of organically modified clay filler can
effectively reduce preform shrinkage and avoid warpage during the
reheating process, which can improve the processability of PS
preforms. In addition, it was also observed that the heating
efficiency and effectiveness was improved. The molded 535/10A
bottles also exhibit high stiffness. The addition of a small amount
of clay into PS preforms not only addresses the processing issue,
but can also improve heating efficiency and bottle, properties.
[0067] Embodiments of the present invention can include preforms
having reheat shrinkage of less than 40%, optionally less than 35%,
optionally less than 30%, or optionally less than 25%. Embodiments
of the present invention can include preforms having reheat warpage
of less than 8%, optionally less than 6%, optionally less than 4%,
optionally less than 3%, or optionally less than 2%.
[0068] Embodiments of the present invention can include preforms
having clay nanoplatelets in a PS matrix capable of absorbing IR
waves. The preforms of the present invention can reach a
temperature higher than that of a substantially similar preform
without clay nanoplatelets under the same conditions. The
temperature can be at least 5.degree. F. higher, optionally at
least 10.degree. F. higher, or at least 15.degree. F. higher than
that of a substantially similar preform without clay nanoplatelets
under the same conditions.
[0069] Embodiments of the present invention can include preforms
having a nanocomposite layer and a non-nanocomposite layer. A
preform may have an inner layer of nanocomposite material and an
outer layer of non-nanocomposite material. Alternately the preform
may have an inner layer of non-nanocomposite material and an outer
layer of nanocomposite material. Alternately the preform may have
multiple layers that include at least one layer of nanocomposite
material. An example is a preform that has an inner layer of
nanocomposite material with a skin layer on each side of a
non-nanocomposite material. A co-extrusion stretch blow molding
process is one way of producing a preform having multiple
layers.
[0070] Use of broader terms such as comprises, includes, having,
etc. should be understood to provide support for narrower terms
such as consisting of, consisting essentially of, comprised
substantially of, etc.
[0071] The term "affinity" as used herein shall refer to the
tendency of a first material to mix or combine with a second
material of unlike composition, such as a solvent and a solute. As
used herein two materials have an affinity for each other if there
is no more than 3.0 (MPa.sup.1/2) difference between their
solubility parameters.
[0072] The term "composite materials" refers to materials which are
made from two or more constituent materials (e.g., a layered
compound and a polymeric material) with significantly different
physical and/or chemical properties and which remain separate and
distinct on a macroscopic level within the finished structure.
[0073] The term "exfoliation" refers to delamination of a layered
material resulting in the formation of disordered layers or
sheets.
[0074] The term "nanocomposites" refers to materials that are
created by introducing nanoparticulates, also termed filler
materials (e.g., a layered compound) into a macroscopic material
(e.g., a polymeric material), which is typically referred to as the
matrix.
[0075] Use of the term "optionally" with respect to any element of
a claim is intended to mean that the subject element is required,
or alternatively, is not required. Both alternatives are intended
to be within the scope of the claim. Use of broader terms such as
comprises, includes, having, etc. should be understood to provide
support for narrower terms such as consisting of, consisting
essentially of, comprised substantially of, etc.
[0076] The term "processing" is not limiting and includes
agitating, mixing, milling, blending, etc. and combinations
thereof, all of which are used interchangeably herein. Unless
otherwise stated, the processing may occur in one or more vessels,
such vessels being known to one skilled in the art.
[0077] Depending on the context, all references herein to the
"invention" may in some cases refer to certain specific embodiments
only. In other cases it may refer to subject matter recited in one
or more, but not necessarily all, of the claims. While the
foregoing is directed to embodiments, versions and examples of the
present invention, which are included to enable a person of
ordinary skill in the art to make and use the inventions when the
information in this patent is combined with available information
and technology, the inventions are not limited to only these
particular embodiments, versions and examples. Other and further
embodiments, versions and examples of the invention may be devised
without departing from the basic scope thereof and the scope
thereof is determined by the claims that follow.
* * * * *