U.S. patent application number 14/764876 was filed with the patent office on 2015-12-31 for grafted polyethylene.
This patent application is currently assigned to SACO POLYMERS, INC.. The applicant listed for this patent is SACO POLYMERS, INC.. Invention is credited to Jeffrey Jacob Cernohous, Neil R. Granlund, David Geraint Roberts.
Application Number | 20150376409 14/764876 |
Document ID | / |
Family ID | 51625299 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150376409 |
Kind Code |
A1 |
Cernohous; Jeffrey Jacob ;
et al. |
December 31, 2015 |
GRAFTED POLYETHYLENE
Abstract
Grafted polyethylene polymers and copolymers are reactively
extruded to achieve enhanced rheological properties. The
utilization of an oligomeric or polymeric wax in the reactive
extrusion process with functionalized agents, results in improved
rheological characteristics of the grafted polymer.
Inventors: |
Cernohous; Jeffrey Jacob;
(Hudson, WI) ; Roberts; David Geraint; (Sheboygan
Falls, WI) ; Granlund; Neil R.; (Columbia Heights,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SACO POLYMERS, INC. |
Sheboygan |
WI |
US |
|
|
Assignee: |
SACO POLYMERS, INC.
Sheboygan
WI
|
Family ID: |
51625299 |
Appl. No.: |
14/764876 |
Filed: |
March 13, 2014 |
PCT Filed: |
March 13, 2014 |
PCT NO: |
PCT/US14/25513 |
371 Date: |
July 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61783177 |
Mar 14, 2013 |
|
|
|
Current U.S.
Class: |
524/585 |
Current CPC
Class: |
C08L 51/06 20130101;
C08F 255/02 20130101; C08F 255/02 20130101; C08L 91/06 20130101;
C08L 51/06 20130101; C08L 91/06 20130101; C08F 222/06 20130101 |
International
Class: |
C08L 91/06 20060101
C08L091/06; C08L 51/06 20060101 C08L051/06 |
Claims
1. A composition comprising a melt processable grafted polymer
composition derived from the combination of: (i) a polyethylene or
polyethylene copolymer, (ii) an oligomeric or polymeric wax, (iii)
a functionalized agent, and (iv) a free radical initiator.
2. A composition according to claim 1, wherein the free radical
initiator includes organic peroxides or diazo compounds.
3. (canceled)
4. A composition according to claim 1 wherein the oligomeric or
polymeric wax is a polyethylene wax, polypropylene wax,
triglyceride wax, diglyceride wax, monoglyceride wax, fatty acid
wax, fatty amide wax, metal stearates or combinations thereof.
5. A composition according to claim 1, wherein the functionalized
agent includes ethylenically unsaturated monomers having a reactive
group.
6. A composition according to claim 1, wherein the functionalized
agent includes functionalized acrylates, functionalized
methacrylates, functionalized styrenics, functionalized dienes,
functionalized olefins, or combinations thereof.
7. A composition according to claim 1, wherein the functionalized
agent includes an electrophilic or nucleophilic reactive moiety
selected from amines, amides, esters, carboxylic acids, carboxylic
acid halides, anhydrides, imides, alcohols, isocyanates,
oxazolines, epoxides and silanes.
8. A composition according to claim 1, wherein the melt processable
polymeric composite has a melt flow index value according to ASTM
D1238 of at least a 100% greater value than a melt flow index of a
corresponding grafted polyethylene or polyethylene copolymer
produced in the absence of the oligomeric or polymeric wax.
9. The composition according to claim 1, wherein the melt
processable grafted polymer composition comprises a grafted
polyethylene or polyethylene copolymer.
10. (canceled)
11. A method of producing the composition according to claim 1
comprising melt processing a polyolefin or polyolefin copolymer
with an oligomeric or polymeric wax, maleic anhydride, and a free
radical initiator to form a grafted polyethylene polymer or
polyethylene copolymer.
12-13. (canceled)
14. A melt processable, grafted polymer composition formed by melt
processing a mixture comprising (a) polyethylene and/or
polyethylene copolymer; (b) oligomeric and/or polymeric wax having
a weight average molecular weight of less than 50,000 g/mol; (c)
functionalized agent, which includes an ethylenically unsaturated
monomer having a reactive group; and (d) free radical
initiator.
15. The composition of claim 14, wherein the reactive group is a
carboxylic acid and/or carboxylic anhydride.
16. The composition of claim 14, wherein the functionalized agent
includes maleic anhydride.
17. The composition of claim 14, wherein the mixture comprises high
density polyethylene, low density polyethylene and/or linear low
density polyethylene.
18. The composition of claim 14, wherein the oligomeric and/or
polymeric wax has a weight average molecular weight of less than
10,000 g/mol and comprises polyethylene wax, polypropylene wax,
triglyceride wax, diglyceride wax, monoglyceride wax, fatty acid
wax, and/or fatty amide wax.
19. The composition of claim 14, wherein the mixture comprises high
density polyethylene resin (HDPE), polyethylene wax, and maleic
anhydride.
20. The composition of claim 14, wherein the mixture comprises
about 20 to 90 wt. % of the polyethylene and/or polyethylene
copolymer; about 1 to 80 wt. % of the oligomeric or polymeric wax;
and about 1 to 10 wt. % of the functionalized agent.
21. The composition of claim 14, wherein the mixture comprises
about 20 to 90 wt. % high density polyethylene resin; about 1 to 80
wt. % polyethylene wax; and about 0.5 to 5 wt. % maleic
anhydride.
22. The composition of claim 21, wherein the melt processable,
grafted polymer composition has a melt flow index value according
to ASTM D1238 of at least a 100% greater value than a melt flow
index of a corresponding grafted polyethylene produced in an
absence of the oligomeric or polymeric wax.
23. A melt processable, grafted polymer composition formed by melt
processing a mixture comprising (a) polyethylene; (b) oligomeric
and/or polymeric wax having a weight average molecular weight of
less than 50,000 g/mol; (c) an ethylenically unsaturated monomer
having a reactive group; and (d) free radical initiator; wherein
the oligomeric and/or polymeric wax comprises polyethylene wax,
polypropylene wax, triglyceride wax, diglyceride wax, monoglyceride
wax, fatty acid wax, and/or fatty amide wax.
24. The composition of claim 23, wherein the mixture comprises
about 20 to 90 wt. % of the polyethylene, which includes high
density polyethylene; about 1 to 80 wt. % of the oligomeric and/or
polymeric wax, which includes the polyethylene wax; and about 0.5
to 5 wt. % of the ethylenically unsaturated monomer, which includes
maleic anhydride.
25. The composition of claim 1, wherein the combination comprises
about 20 to 90 wt. % of the polyethylene or polyethylene copolymer;
about 1 to 80 wt. % of the oligomeric and/or polymeric wax; and
about 0.5 to 5 wt. % of the functionalized agent; wherein the
polyethylene or polyethylene copolymer includes high density
polyethylene; the oligomeric or polymeric wax has a weight average
molecular weight of less than 10,000 g/mol and includes
polyethylene wax; the functionalized agent includes maleic
anhydride; and the melt processable grafted polymer composition has
a melt flow index value according to ASTM D1238 of at least a 100%
greater value than a melt flow index of a corresponding grafted
polyethylene or polyethylene copolymer produced in the absence of
the oligomeric or polymeric wax.
Description
TECHNICAL FIELD
[0001] This disclosure is related to the modification of the
rheological properties of polyethylene or polyethylene
copolymers.
BACKGROUND
[0002] Polyolefins are commonly modified by reactive extrusion. The
modification is often desirable in order to facilitate the blending
of the generally incompatible polyolefins with other polymers.
Reactive extrusion functionalizes the polyolefins and thus is a
method typically employed to overcome their incompatibility issue
with other polymers. Most polyolefins, such as polypropylene, upon
grafting have desirable functional rheological properties that
permit secondary manipulation or formation of a desired end
product. However, the rheological properties of polyethylene or
polyethylene copolymers generally change to a less desirable state.
One characteristic of grafted polyethylene polymers and copolymers
is that their melt flow index decreases upon grafting when compared
to the polymer in the ungrafted state.
SUMMARY
[0003] In the grafting of functional monomers with polyethylene
polymers and copolymers, it is generally recognized that the
rheological properties of the resulting grafted polymers will not
be in the most efficient or effective state for secondary
processing. This disclosure is directed at the use of oligomeric or
polymeric waxes incorporated into the reactive extrusion process
for forming grafted polyethylene polymers and copolymers with
enhanced rheological properties.
[0004] The utilization of an oligomeric or polymeric wax during the
reactive extrusion of polyethylene polymers or polyethylene
copolymers, functionalizing agents, and free radical initiators
during reactive extrusion practices results in grafted polyethylene
polymers or polyethylene copolymers that have enhanced rheological
properties. One particular convention for measuring rheological
properties of a polymeric melt is the melt flow index, as specified
under ASTM D1238. In certain embodiments, the grafted polyethylene
polymers or polyethylene copolymers, produced in accordance with
this disclosure, exhibit melt flow indices ("MFI") of at least 50%
greater when compared to the functionalized polyethylene copolymer
produced in the absence of an oligomeric or polymeric wax. Other
non-limiting examples of rheological properties that may also be
enhanced include melt viscosity, melt transition temperature
(T.sub.m), glass transition temperature (T.sub.g), and the storage
modulus (G') and/or loss modulus (G'') at a specified temperature
or shear rate.
[0005] The grafted polyethylene polymers and copolymers are
suitable for various applications such as compatibilizers, coupling
agents, viscosity modifiers, surface modifiers, lubricants, impact
modifiers and tie-layers. The grafted polyethylene polymers have
specific application as coupling agents for glass, mineral or
natural fiber filled polyolefins. By controlling or tailoring the
rheology of the grafted polyethylene, it is possible to improve the
effectiveness and performance in such composite systems. In one
embodiment, it is desirable to increase the melt flow index and
subsequent flow properties of the grafted polyethylene polymer to
improve the likelihood of successful interfacial bonding during
melt processing of the composite system. In another embodiment, it
is important to tailor the rheology of the grafted polyethylene
polymer in order to match the rheology of the polymer matrix the
additive is being blended into. In another embodiment, it is
important to tailor the rheology of the grafted polyethylene
polymer in a tie-layer application in order to match the rheology
of other polymers being simultaneously coextruded with the grafted
polyethylene polymer.
DETAILED DESCRIPTION
[0006] Enhanced or improved rheological properties of polyethylene
polymers or copolymers is contemplated by a melt processable
polymeric composite derived from the combination of a polyethylene
or polyethylene copolymer, an oligomeric or polymeric wax, a
functionalized agent, and a free radical initiator. Melt processing
the polyolefin or polyolefin copolymer with an oligomeric or
polymeric wax, maleic anhydride, and a functionalized agent forms a
grafted polyethlyene polymer or polyethylene copolymer with
desirable and improved rheological properties.
[0007] Polyethylene or polyethylene copolymers function as the host
polymer and are a component of the melt processable composition
subjected to the reactive extrusion process along with the other
components. A wide variety of polyethylene polymers and copolymers
conventionally available and suitable for melt processing are
useful. The polyethylene or polyethylene copolymers may comprise
from about 20% to about 90% by weight of the entire composition. A
non-limiting example of a commercially available polymer includes
Dowlex IP40, high density polyethylene from Dow Chemical
Corporation, Midland, Mich. Other conventional low density and
linear low density polyethylene polymers or copolymers are suitable
as well. The polyethylene or polyethylene copolymers may comprise
from about 20% to about 90% by weight of the entire
composition.
[0008] Oligomeric or polymeric waxes are generally those low
molecular weight waxes that have a weight average molecular weight
of less than 50,000 g/mol, and are compatible with the polyethylene
matrix during melt processing. In some embodiments, the low
molecular weight wax has a weight average molecular weight of less
than 20,000 g/mol. In most preferred embodiments, the low molecular
weight wax has a weight average molecular weight of less than
10,000 g/mol. Non-limiting examples of oligomeric and polymeric
waxes include, polyethylene waxes, polypropylene waxes,
triglyceride waxes, diglyceride waxes, monoglyceride waxes, fatty
acid waxes, fatty amide waxes, and metal stearates.
[0009] The amount of oligomeric or polymeric wax present in the
melt processable composition is dependent upon several variables,
such as for example, the polyethylene polymer or copolymer, the
type of functionalizing agent, the type of melt processing
equipment, the processing conditions, and others. Those of ordinary
skill in the art with knowledge of this disclosure are capable of
selecting an appropriate amount of oligomeric or polymeric wax to
achieve the desired result. In certain embodiments, the oligomeric
or polymeric wax is used at 0.01 to 80 wt % by weight of the melt
processable composition.
[0010] In other embodiments, the oligomeric or polymeric wax is
used at 1.0 to 50 wt % by weight of the melt processable
composition.
[0011] Functionalizing agents enable the incorporation of a
reactive moiety onto the backbone of the polyethylene polymers and
polyethylene copolymers. The resulting functionalized polyethylene
polymer or copolymer can have utility as an interfacial modifier
(e.g., compatibilizer, coupling agent, surface modifier,
tie-layer). The grafting process that takes place in the melt is
accomplished by free radical grafting of an unsaturated polar
monomer or functionalizing agent onto the polyethylene polymer or
copolymer. Non-limiting examples of functionalized agents include
ethylenically unsaturated monomers having a reactive group.
Examples include functionalized acrylates, methacrylates,
stryenics, dienes and olefins. The reactive group may be any
electrophilic or nucleophilic reactive moiety. Non-limiting
examples of reactive groups include: amines, amides, esters,
carboxylic acids, carboxylic acid halides, anhydrides, imides,
alcohols, isocyanates, oxazolines, epoxides and silanes. The
functionalizing agents may be included in the melt processable
composition in amounts ranging from about 0.1% to about 10% by
weight. In certain embodiments, the functionalized agent may be
included at about 0.5% to about 5% by weight.
[0012] A free radical initiator is a species that, when melt
processed, forms reactive free radical moieties that influence the
grafting process in the extruder. Free radical initiators useful in
the grafting process include organic peroxides and diazocompounds.
Non-limiting examples of specific free radical initiators include:
benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide and
azoisobutrylnitrile. The free radical initiator may be included in
the melt processable composition at amounts less than 1% by
weight.
[0013] The melt processable composition can be prepared by any of a
variety of ways. For example, the polyethylene polymers and
polyethylene copolymers, the oligomeric or polymeric wax, and the
functionalized agent can be combined together by any of the
blending means usually employed in the plastics industry.
[0014] Melt-processing typically is performed at a temperature from
120.degree. to 300.degree. C., although optimum operating
temperatures are selected depending upon the melting point, melt
viscosity, and thermal stability of the composition. Different
types of melt processing equipment, such as extruders, may be used
to process the melt processable compositions of this invention. In
one embodiment, an extruder is utilized to enable a reactive
extrusion of the components. Those of ordinary skill in the art in
polymer processing are able to select appropriate operating
conditions based upon the specific materials utilized for forming
the grafted polyethylene or polyethylene copolymer.
[0015] In some embodiments, the melt processing and reactive
extrusion is performed in a twin screw extruder. In another
embodiment, the reactive extrusion is performed in a co-rotating,
segmented twin screw extruder. In such instances, it is preferable
that the length:diameter of the twin screw extruder is at least
32:1. In yet another embodiment, the length:diameter of the twin
screw extruder is at least 40:1. Those who are skilled in the art
will recognize preferred screw designs and temperature profiles to
achieve optimal reactive extrusion to produce the grafted
polyethylene or polyethylene copolymers.
[0016] The resulting grafted polyethylene or polyethylene
copolymers possess desirable rheological characteristics. For
example, grafted polyethylene polymers and polyethylene copolymers
made in accordance with this disclosure can exhibit enhanced or
improved melt flow indices as measured in accordance with ASTM
D1238. The grafted polyolefin or polyethylene copolymer has a melt
flow index value according to ASTM D1238 of at least 50% greater
value than the melt flow index of a grafted polyethylene or
polyethylene copolymer produced in the absence of the oligomeric or
polymeric wax. In certain embodiments, the melt flow index is at
least 100% greater and may be at least 200% greater.
[0017] In other embodiments, rheological properties such as
flexural strength, flexural modulus, tensile strength, tensile
modulus, tensile elongation, moisture resistance and impact
properties may be enhanced.
[0018] The grafted polyethylene polymers and copolymers are
suitable for various applications such as compatibilizers, coupling
agents, viscosity modifiers, surface modifiers, lubricants, impact
modifiers and tie-layers.
EXAMPLES
TABLE-US-00001 [0019] Material Supplier PE1 Dowlex IP40, high
density polyethylene, commercially available from Dow Chemical
Corporation, Midland, MI. Wax 1 Bareco C4040 polymer, polyethylene
wax, commercially available from Baker Petrolite Corporation,
Sugarland, TX. Maleic Commercially available from Aldrich Chemical
Anhydride Co., Milwaukee, WI. DHBP 2,5-Dimethyl-2,5-di(tertbutyl
peroxy) hexane, commercially available from United Initiators,
Elyria, OH.
Compounding Procedure for CE1 and Examples 1-2
[0020] For Comparative Example CE1 and examples 1-2, polyethylene
resin, wax, maleic anhydride and DHBP were dry blended in a plastic
bag and fed using a gravimetric feeder into a 26 mm co-rotating
twin screw extruder (40:1, L:D) fitted with a four strand die
(commercially available from Lab Tech Engineering, Samutprakarn,
Thailand). All samples were processed at 250 rpm screw speed using
the following temperature profile: Zone 1-2=160.degree. C., Zone
3-4=190.degree. C., Zone 5-6=210.degree. C., Zone 7-8=190.degree.
C., 9-10=180.degree. C. Die=170.degree. C. The resulting strands
were subsequently continuously processed into a room temperature
water bath and pelletized into 0.64 cm pellets. The resulting
pellets were tested for melt flow index following ASTM D1238. The
test was performed at 190.degree. C. with a 2.2 Kg mass.
[0021] Table 1 gives the formulations for comparative example CE1
and Examples 1-2. Table 2 gives the properties for comparative
example CE1 and Examples 1-2.
TABLE-US-00002 TABLE 1 Formulation for CE1 and Examples 1-2 Maleic
Compatibilizer PE1 Wax Anhydride DHBP CE1 97.9 -- 2 0.1 1 72.9 25 2
0.1 2 47.9 50 2 0.1
TABLE-US-00003 TABLE 2 Properties of Formulation CE1 and Examples
1-2 Melt Flow Index Example (g/10 min) CE1 1.20 1 12.30 2
102.70
* * * * *