U.S. patent application number 13/033668 was filed with the patent office on 2012-08-30 for high melt strength polypropylene and methods of making same.
This patent application is currently assigned to Fina Technology, Inc.. Invention is credited to John Ashbaugh, Robert Dotter, Fengkui Li, David Rauscher.
Application Number | 20120220730 13/033668 |
Document ID | / |
Family ID | 46719435 |
Filed Date | 2012-08-30 |
United States Patent
Application |
20120220730 |
Kind Code |
A1 |
Li; Fengkui ; et
al. |
August 30, 2012 |
High Melt Strength Polypropylene and Methods of Making Same
Abstract
A high melt strength polypropylene is formed using maleated
polypropylene and a combination of coupling agents and acid
neutralizers. The maleated polypropylene can be formed using
multi-functional monomers. The high melt strength polypropylene can
be useful for foaming, sheet extrusion thermoforming, extrusion
blow molding, extrusion coating, fiber, film, and the like.
Inventors: |
Li; Fengkui; (Houston,
TX) ; Ashbaugh; John; (Houston, TX) ;
Rauscher; David; (Angleton, TX) ; Dotter; Robert;
(Fresno, TX) |
Assignee: |
Fina Technology, Inc.
Houston
TX
|
Family ID: |
46719435 |
Appl. No.: |
13/033668 |
Filed: |
February 24, 2011 |
Current U.S.
Class: |
525/304 ;
525/333.7; 525/333.8; 525/360; 525/369; 525/371; 525/379;
525/382 |
Current CPC
Class: |
C08J 9/00 20130101; C08L
23/26 20130101; C08F 10/06 20130101 |
Class at
Publication: |
525/304 ;
525/333.7; 525/333.8; 525/379; 525/382; 525/360; 525/369;
525/371 |
International
Class: |
C08L 23/26 20060101
C08L023/26; C08F 8/32 20060101 C08F008/32; C08F 8/14 20060101
C08F008/14 |
Claims
1. A high melt strength polypropylene comprising a functionalized
polypropylene and a coupling agent.
2. The high melt strength polypropylene of claim 1, wherein the
high melt strength polypropylene exhibits enhanced processability
and performance in the molten state, as compared to neat
polypropylene.
3. The high melt strength polypropylene of claim 1, wherein the
functionalized polypropylene is maleated polypropylene.
4. The high melt strength polypropylene of claim 1, wherein the
functionalized polypropylene is maleated polypropylene that is
formed by the reactive extrusion of polypropylene, a peroxide,
maleic anhydride, and 0.1 to 5% by weight of a multi-functional
monomer.
5. The high melt strength polypropylene of claim 4, wherein the
multi-functional monomer is chosen from the group consisting of di-
and tri-acrylates.
6. The high melt strength polypropylene of claim 1, wherein the
coupling agent is 1,3-phenylenediamine or other diamines.
7. The high melt strength polypropylene of claim 1 further
comprising an acid neutralizer.
8. The high melt strength polypropylene of claim 7, wherein the
acid neutralizer is a metal salt.
9. The high melt strength polypropylene of claim 7, wherein the
acid neutralizer is chosen from the group consisting of: potassium
hydroxide, zinc stearate, zinc acetate, sodium hydroxide, and
combinations thereof
10. The high melt strength polypropylene of claim 7 further
comprising a commercial ionic monomer.
11. An article made from the high melt strength polypropylene of
claim 1.
12. A high melt strength polypropylene comprising maleated
polypropylene that has been formed in the presence of an acrylate
multi-functional monomer, an amine coupling agent, and an acid
neutralizer.
13. The high melt strength polypropylene of claim 12, used as a
masterbatch for enhancing the melt strength of conventional
polypropylene resin.
14. The high melt strength polypropylene of claim 12, used in one
of the following applications: foaming, sheet extrusion
thermoforming, extrusion blow molding, extrusion coating, fiber,
and film.
15. A method of making a high melt strength polypropylene,
comprising: reactively blending a combination a functionalized
polypropylene and an amine coupling agent, and recovering a
polypropylene product of enhanced melt strength.
16. The method of claim 15, wherein the functionalized
polypropylene is maleated polypropylene, that is formed by the
reactive extrusion of a peroxide, maleic anhydride, and 0.1 to 5%
by weight of a multi-functional monomer.
17. The method of claim 16, wherein the multi-functional monomer is
chosen from the group consisting of di- and tri-acrylates.
18. The method of claim 15, wherein the coupling agent is
1,3-phenylenediamine.
19. The method of claim 15, wherein the step of reactive blending
includes an acid neutralizer.
20. The method of claim 19, wherein the acid neutralizer is a metal
salt.
21. The method of claim 19, wherein the acid neutralizer is chosen
from the group consisting of: potassium hydroxide, zinc stearate,
zinc acetate, sodium hydroxide, and combinations thereof
22. The method of claim 19, wherein the step of reactive blending
further includes a commercial ionic monomer.
23. A method of making a high melt strength polypropylene,
comprising: reactively blending a combination of maleated
polypropylene that has been formed in the presence of an acrylate
multi-functional monomer, an amine coupling agent, and an acid
neutralizer; and recovering a polypropylene product of enhanced
melt strength.
Description
FIELD
[0001] The present invention generally relates to methods of making
high melt strength polypropylene.
BACKGROUND
[0002] Polypropylene is a widely used plastic that has high
modulus, high tensile strength, good heat resistance, and other
favorable properties in the sold-state. However, due to its linear
molecular architecture, polypropylene generally has relatively poor
melt strength, which negatively affects its processability while in
the molten state. Low melt strength limits polypropylene resins in
a number of applications, such as foaming, sheet extrusion
thermoforming, extrusion blow molding, extrusion coating, and the
like.
[0003] The melt strength is generally increased by the addition of
long-chain branches to the polymer structure. On the other hand,
long chain branches bonded within the polymer structure can make
the polymer too rigid, compromising the polymer's thermoplastic
character. Thus, methods of making high melt strength polypropylene
(HMS-PP) are needed to promote long chain branching without
sacrificing the thermoplastic character.
SUMMARY
[0004] The present invention concerns methods of making high melt
strength polypropylene (HMS-PP). Embodiments include methods of
making HMS-PP that includes a functionalized polypropylene and some
combination of coupling agents and acid neutralizers. In an
embodiment, the functionalized polypropylene is maleated
polypropylene, optionally formed in the presence of 0.1 to 5% by
weight of a multi-functional monomer, chosen from the group
containing diacrylates, triacrylates, and other acrylates. The high
melt strength polypropylene can exhibit enhanced processability and
performance in the molten state, as compared to neat
polypropylene.
[0005] In an embodiment, the coupling reactions are achieved using
a coupling agent, such as a diamine, for instance,
1,3-phenyldiamine. The coupling agent can react with maleic
anhydride when maleated polypropylene is used to form the
HMS-PP.
[0006] In an embodiment, the HMS-PP is formed in the presence of an
acid neutralizer, and the resultant polymer is an ionomer. The acid
neutralizer is generally a metal salt, such as potassium hydroxide,
zinc stearate, or zinc acetate. In an embodiment a commercial ionic
monomer, such as SR732, from Sartomer can be included.
[0007] In an embodiment, the HMS-PP is formed in the presence of
both a coupling agent and an acid neutralizer that can
synergistically be used to enhance the melt strength of the polymer
product.
[0008] The HMS-PP can be useful for applications such as foaming,
sheet extrusion thermoforming, extrusion blow molding, extrusion
coating, fiber, film, molding, and the like. The HMS-PP can also be
used as masterbatches for enhancing the melt strength of
conventional polypropylene resins.
[0009] In an embodiment, the invention is a method for forming
HMS-PP that includes the steps of: reactively blending a maleated
PP, a coupling agent, and an acid neutralizer, and recovering a
polypropylene product of enhanced melt strength. The reactive
blending is generally a reactive extrusion, performed at
temperature of from 190 to 230.degree. C. The maleated PP is
desirably formed in the presence of an acrylate multi-functional
monomer.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIGS. 1a-c show torque as a function of time for
polypropylene compositions containing potassium hydroxide, zinc
acetate, and zinc stearate, respectively.
[0011] FIG. 2 shows torque as a function of time for maleated
polypropylene and maleated polypropylene that was formed with a
multifunctional monomer, respectively.
[0012] FIGS. 3a-b show torque as a function of time for
amine-coupled polypropylene compositions containing maleated
polypropylene and maleated polypropylene that was formed with a
multifunctional monomer, respectively.
DETAILED DESCRIPTION
[0013] The present invention involves high melt strength
polypropylene (HMS-PP) and methods of making it. The composition of
the HMS-PP includes a functionalized polypropylene and a coupling
agent, acid neutralizer, or both, the constituents of the HMS-PP
varying according to different embodiments.
[0014] In all embodiments, the HMS-PP includes a functionalized
polypropylene, which includes polypropylene, a free radical
initiator and a graftable monomer. The polypropylene can be a
homopolymer, or a copolymer containing at least 50% by weight of
polypropylene and a remaining portion of a C.sub.2-C.sub.20 olefin.
The polypropylene can have a crystallinity of at least 30%, and a
stereoregularity of at least 60%. The polypropylene can be
isotactic or syndiotactic, with a melt flow index (MFI) of from 0.1
to 100 g/10 min, optionally from 1.0 to 80 g/10 min, optionally
from 5.0 to 50 g/10 min. MFI being measured according to ASTM D
1238 standard at 230.degree. C. under a load of 2.16 kg. In
embodiments of the present invention the polypropylenes can have a
weight average molecular weight distribution (MWD), determined by
ASTM D5296-05, ranging from 150,000 to 850,000, optionally ranging
from 200,000 to 600,000, optionally ranging from 300,000 to
500,000, optionally ranging from 250,000 to 400,000, and optionally
ranging from 350,000 to 400,000.
[0015] Optionally, the polypropylene can be an impact copolymer
(ICP). The ICP may be one having a density range from 0.88 to 0.93
g/cm.sup.3, optionally from 0.89 to 0.92 g/cm.sup.3, and,
optionally from 0.9 to 0.91 g/cm.sup.3. In an embodiment, the ICP
may have a melting point ranging from 155 to 170.degree. C.,
optionally from 158 to 166.degree. C., optionally from 160 to
165.degree. C. ICP polypropylene may have a melt flow rate (MFR)
ranging from 0.1 to 40 g/10min. In an alternative embodiment, the
ICP polypropylene may have a MFR ranging from 1 to 30 g/10 min,
optionally from 3 to 20 g/10 min, optionally from 5 to 10 g/10 min.
The ICPs used herein can have a weight average molecular weight
distribution (MWD) ranging from 280,000 to 850,000, optionally
ranging from 320,000 to 780,000, optionally ranging from 420,000 to
700,000.
[0016] The initiator is generally a peroxide, optionally an organic
peroxide, and more particularly an alkyl peroxide, such as
ditertiary butyl peroxide, tertiary butyl hydroperoxide, cumene
hydroperoxide, p-menthane peroxide, p-menthane hydroperoxide (some
might be repeats) tert-butylcumyl peroxide,
1,3-di(2-tert-butylper-oxyisopropyl)benzene,
2,5-dimethyl-2,5-di(tert-butyl-peroxy)hexane,
di(tert-butyl)peroxide,
2,5-dimethyl2,5-di(tert-butylperoxy)-3-hexane, and
2,5-dimethyl-2,5-di-tert-butylperoxyhexane (DHBP). The peroxide can
range from 0.001 to 0.5% by weight, optionally from 0.01 to 0.3%,
optionally from 0.01 to 0.1%, with respect to the
polypropylene.
[0017] The graftable monomer generally contains a carbonyl,
carboxylic acid or acid anhydride functional group and can be
chosen from the following: acrylic acid, methacrylic acid, maleic
acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid,
maleic anhydride, itaconic anhydride, crotonic anhydride and
citraconic anhydride, maleic anhydride, and allyl methacrylate. The
graftable monomer can range from 0.01 to 10% by weight, optionally
from 0.1 to 10%, optionally from 1.0 to 5.0%, with respect to the
polypropylene.
[0018] In an embodiment, the graftable monomer is maleic anhydride,
and the functionalized polypropylene is maleated polypropylene. A
commercial maleated PP can be used for the functionalized
polypropylene, such as for example Polybond 3150 or Polybond 3200,
commercially available from Chemtura.
[0019] In an embodiment, the functionalized polypropylene includes
0.1 to 10% by weight, optionally from 0.1 to 5%, optionally from
0.1 to 3%, of a multi-functional monomer, such as di-acrylates,
triacrylates, etc. Multi-functional monomers can increase the
degree of grafting. The multi-functional monomer can be an acrylate
containing from 3 to 5 acrylate groups, such as trimethylolpropane
triacrylate, trimethylolpropane ethoxylate triacrylate, glycerol
propoxylate triacrylate, pentaerythritol triacrylate,
di(trimethylolpropane) tetraacrylate, pentaerythritol
tetraacrylate, pentaerythritol ethoxylate tetraacrylate,
trimethylolpropane trimethacrylate, pentaerythritol ethoxylate
triacrylate, and polyethylene glycol diacrylate.
[0020] In an embodiment, the functionalized polypropylene is
maleated polypropylene, formed in the presence of an acrylate
multi-functional monomer. Commercial maleated polypropylene resins
can be used to make HMS-PP; however, the reactive extrusion of
polypropylene with maleic anhydride and peroxide generally involves
a significant break-up of high molecular weight chains, or
vis-breaking Reducing polypropylene vis-breaking during maleated PP
production can increase the number of potential long chain branches
that can be formed when the HMS-PP of the invention includes
coupling reactions and can be beneficial for long term performance
of PP-based ionomers upon neutralization.
[0021] In an embodiment, the HMS-PP includes an acid neutralizer,
and the HMS-PP is a polypropylene ionomer. A graftable monomer
containing a carbonyl, carboxylic acid or acid anhydride functional
group can be neutralized by metal cations. For instance, maleated
polypropylene contains carboxylic acids in the polymer chain. The
addition of acid neutralizers yields a polypropylene ionomer. The
polar groups tend to congregate, creating crosslinks throughout the
polymer chain. At high temperatures, the attraction of the polar
groups is weakened. Thus, the crosslinks created by acid
neutralization are reversible, and it is possible to increase the
melt strength of polypropylene while retaining its thermoplastic
character.
[0022] Acid neutralizers used for the present invention can be
salts, optionally metallic salts. The cationic portion of the metal
salt can be an alkali cation, an alkaline-earth cation, or a
transition-metal cation, while the anionic potion of the metal salt
can be an alcoholate, carboxylate, hydroxide, oxide, alkyl,
carbonate, or hydrogen-carbonate. The acid neutralizer can be
chosen from the following: sodium hydroxide, calcium oxide, sodium
carbonate, sodium hydrogencarbonate, sodium methoxide, sodium
acetate, magnesium ethoxide, diethylzinc, aluminium butoxide,
zirconium butoxide, potassium hydroxide, zinc acetate, zinc
stearate, and the like. The acid neutralizer can be potassium
hydroxide, zinc acetate, or zinc stearate. The acid neutralizer can
be present in an amount from 0.1 to 10% by weight, optionally from
0.1 to 7.5% by weight, optionally 0.1 to 5% by weight. Small
amounts of water, such as from 0.5 to 1% by weight, can be used to
expedite the neutralization reaction. Acrylate ionic monomers, such
as SR 732, commercially available at Sartomer, can be added to aid
the neutralization reaction in an amount from 0.1 to 5% by weight,
optionally from 0.1 to 2.5% by weight, optionally from 0.5 to 1% by
weight.
[0023] In another embodiment, the HMS-PP includes an amine coupling
agent. The amine can be chosen from the group containing
C.sub.4-C.sub.12 alkylene diamines, hexamethylene diamine (HMDA),
polypropylene glycol)-bis-(2-propylamine) hexamethylenediamine,
dodecamethylenediamine, and 1,3-phenylenediamine. A desirable
coupling agent is 1,3-phenylenediamine. The amine can be present in
an amount from 0.1 to 5% by weight, optionally from 0.1 to 2.5% by
weight, optionally from 0.5 to 2% by weight.
[0024] In an embodiment, the HMS-PP includes maleated
polypropylene, formed in the presence of an acrylate
multi-functional monomer, a coupling agent, and an acid
neutralizer. According to this embodiment, the interactions of the
previously described embodiments are synergistically combined to
enhance the melt strength of the polymer and increase long chain
branching, without compromising its thermoplastic character.
[0025] In all embodiments, the HMS-PP can further include
conventional additives such as, for example, stabilizers,
antioxidants, lubricants, antistatic agents, nucleating agents,
foaming agents, glass fibers or any other fillers.
[0026] In all embodiments, the components of the HMS-PP can be
combined using reactive blending, such as reactive extrusion. The
formation of HMS-PP can include either one or two reactive
extrusions. In one embodiment, the polypropylene, free radical
initiator, graftable monomer, and optionally a multi-functional
monomer, are combined in a first reactive extrusion to form a
functionalized polypropylene, such as maleated polypropylene. The
functionalized polypropylene can then be combined with a
neutralizing agent, coupling agent, or some combination thereof in
a second reactive extrusion. In other embodiments, the components
of the functionalized polypropylene can be combined with the
neutralizing agent, coupling agent, and other additives in a single
extrusion. In any case, the order of introduction of the different
components into the mixers is not critical. Such a process can be
performed using any extruder type, such a twin-screw extruder, the
extruder can be a device that extrudes pellets as well as an
extruder which produces sheet, or any other known type. The
reactive extrusion can be performed at a temperature above the
melting point of the polypropylene, generally from 150.degree. to
300.degree. C., optionally from 160.degree. to 250.degree. C., or
optionally from 190.degree. to 230.degree. C.
[0027] HMS-PPs of the present invention can vary greatly in
mechanical and other properties, as there many possible embodiments
within the scope of the invention. Generally, the HMS-PP shows
enhanced melt strength relative to neat polypropylene, as indicated
by increased torque, viscosity, or melt flow rate, for example. For
instance, melt flow rates of HMS-PP can be from 0.001 to 60 g/10
min, optionally from 0.01 to 35 g/10 min, or optionally from 0.1 to
8 g/10 min.
[0028] The HMS-PP can be used alone or as masterbatches, for
blending with other polymer resins, such as, polypropylene
homopolymers, impact copolymers, and the like.
[0029] The HMS-PP can be suitable for many applications, including
all known applications of linear polypropylene. For instance, the
HMS-PP can be suitable for foaming, sheet extrusion thermoforming,
extrusion blow molding, extrusion coating, fiber, film, and similar
applications.
[0030] In one embodiment, the invention is a method of making
HMS-PP that includes reactively blending a combination a
functionalized polypropylene and an acid neutralizer and recovering
a polypropylene product of enhanced melt strength. The
functionalized polypropylene can be a maleated polypropylene,
formed in the presence of an acrylate multi-functional monomer. The
acid neutralizer can be one of potassium hydroxide, zinc stearate,
or zinc acetate.
[0031] In one embodiment, the invention is a method of making
HMS-PP that includes reactively blending a functionalized
polypropylene and an amine coupling agent and recovering a
polypropylene product of enhanced melt strength. The functionalized
polypropylene can be a maleated polypropylene, formed in the
presence of an acrylate multi-functional monomer. The amine
coupling agent can be 1,3-phenylenediamine.
[0032] In one embodiment, the invention is a method of making
HMS-PP that includes reactively blending a functionalized
polypropylene, an acid neutralizer, and an amine coupling agent and
recovering a polypropylene product of enhanced melt strength. The
functionalized polypropylene can be a maleated polypropylene,
formed in the presence of an acrylate multi-functional monomer. The
acid neutralizer can be one of potassium hydroxide, zinc stearate,
or zinc acetate, and the amine coupling agent can be
1,3-phenylenediamine.
[0033] In an embodiment, an article can be obtained by subjecting
the HMS-PP composition to a plastics shaping process such as
foaming, sheet extrusion thermoforming, extrusion blow molding,
extrusion coating, blow molding, injection blow molding, injection
stretch blow molding, thermoforming, and the like. The polymeric
composition may be formed into end use articles such as for
example, packaging, office supplies, structural supports, laminate
compositions, polymeric foam substrate, decorative surfaces,
outdoor furniture, point-of-purchase signs and displays, house
wares and consumer goods, building insulation, cosmetics packaging,
outdoor replacement materials, lids and food/beverage containers,
appliances, utensils, electronic components, automotive parts,
enclosures, medical supplies, toys, piping, and the like.
EXAMPLES
[0034] The following examples are meant to be merely illustrative
of particular embodiments of the present invention, and are by no
means limiting of the scope of the invention.
Example A
[0035] Several polypropylene ionomers were prepared and tested
using a Haake torque rheometer to characterize their melt
strengths. The ionomers were prepared via the reactive blending of
maleated polypropylene and an acid neutralizer. The maleated
polypropylene was Polybond 3150, commercially available from
Chemtura, that has a 70 melt flow rate. The acid neutralizers used
were potassium hydroxide (KOH), zinc acetate di-hydrate (ZnAc), and
zinc stearate (ZnSt). Table 1 is a listing of all the prepared
compositions and their melt flow rates.
TABLE-US-00001 TABLE 1 Ionomer compositions and resulting melt flow
rates (g/10 min) used in Example A. Melt flow rate Polypropylene
composition (g/10 min) Neat polybond 3150 70 3150 + 1% KOH 3.1 3150
+ 1% KOH + 0.5% H2O 3.6 3150 + 1% KOH + 1% H2O 2.4 3150 + 2% KOH +
1% H2O 3.3 3150 + 1% ZnAc 30 3150 + 1% ZnAc + 0.5% H2O 17.5 3150 +
1% ZnAc + 1% H2O 12.6 3150 + 2% ZnAc + 1% H2O 21.2 3150 + 1% ZnSt
54 3150 + 1% ZnSt + 0.5% H2O 59 3150 + 1% ZnSt + 1% H2O 53 3150 +
2% ZnSt + 1% H2O 47
[0036] As indicated by Table 1, the addition of metal salt
decreased the melt flow rate, which is indicative of higher melt
strength. Potassium hydroxide decreased the melt flow to the
greatest extent.
[0037] FIG. 1 a shows torque (%) as a function of processing time
for neat Polybond 3150 based ionomer compositions containing
potassium hydroxide. For all polymer compositions, a spike in
torque occurred in the very beginning, when the solid polymer was
added to the torque rheometer. As the solids started to melt, the
torque gradually decreased. Neat Polybond 3150 showed a gradual
torque decrease, indicating that no reaction occurred in the
material. The composition of 3150+1% KOH showed an increase in
torque at about 30 seconds of mixing time, which indicates an
increase in melt strength due to ionic interactions. The
compositions containing small amounts of water showed torque spikes
occurring sooner than that of 3150+1% KOH. Thus, addition of small
amounts of water can expedite the neutralization rate.
[0038] FIG. 1b shows torque (%) as a function of processing time
for neat Polybond 3150 based ionomer compositions containing zinc
acetate. Figure lc shows torque (%) as a function of processing
time for neat Polybond 3150 based ionomer compositions containing
zinc stearate. Both FIGS, 1b and 1c show smaller torque spikes
relative to FIG. 1a. This is consistent with the melt flow rates of
the potassium hydroxide ionomers being much lower than the melt
flow rates of the zinc stearate and zinc acetate ionomers.
Nevertheless, ionomers formed with all three metal salts showed an
overall decrease in melt flow rate and an increase in torque,
indicating an increase in melt strength via ionic interactions.
Example B
[0039] Several ionomers were prepared and tested for melt flow rate
to characterize their melt strengths. The ionomers included
maleated polypropylenes that were formed via the reactive extrusion
of polypropylene, peroxide, maleic anhydride (MAH), and a
multifunctional monomer. The polypropylene was Total Petrochemicals
3270, the peroxide was Lupersol-101, and the multifunctional
monomer was SR259 from Sartomer.
[0040] Table 2 shows the melt flow rates of the polymer
compositions. The addition of multifunctional monomer yields a
maleated polypropylene with a lower melt flow, indicating
vis-breaking was significantly reduced. Neutralization of the neat
and maleated polypropylene compositions were performed with
potassium hydroxide and zinc acetate on a 27mm twin screw extruder.
When maleated polypropylenes of different melt flow rates were
blended with 3% KOH, the resulting ionomers essentially exhibited a
zero melt flow rate. Lower amounts of potassium hydroxide yielded
1.2-6.5 g/10 min melt flow rates. The addition of zinc acetate
resulted in ionomers with moderately lower melt flow rates. Note
that the addition of zinc acetate to neat PP 3270 increased the
melt flow rate. Thus, the moderate decrease of melt flow rates in
the maleated PP materials was likely due to ionic interaction
formation resulting from neutralization.
TABLE-US-00002 TABLE 2 Melt flow rates (g/10 min) of compositions
from Example B. Maleated Maleated Maleated PP PP + PP + Sample
description alone 3% KOH 3% ZnAc Neat 3270 2.7 3.1 3.4 3270 + 2%
MAH + 0.3% L101 50.0 0 31.8 (no multifunctional monomer) 3270 + 2%
MAH + 1% 28.3 0 23.2 SR259 + 0.3% L101 3270 + 2% MAH + 1% 15.6 0
12.7 SR259 + 0.05% L101 3270 + 2% MAH + 1% 15.6 6.5 SR259 + 0.05%
L101 (1% KOH) 3270 + 2% MAH + 1% 15.6 1.2 SR259 + 0.05% L101 (2%
KOH)
[0041] Overall, the results indicate that the use of a
multifunctional monomer to make maleated PP and the use of metal
salts to make PP ionomers both result in lowered melt flow rates,
indicating increased melt strengths.
Example C
[0042] Several polypropylene compositions of maleated polypropylene
combined with a diamine coupling agent were prepared and tested
using a Haake torque rheometer to characterize their melt
strengths. Two different maleated polypropylenes were prepared on a
27mm twin screw extruder and shall be referred to as PP-A and PP-B.
PP-A was the mixture of polypropylene Total Petrochemicals 3271, 2%
maleic anhydride, and 0.05% Lupersol 101. PP-B included the same
constituents as PP-A, plus 1% SR259, a multifunctional monomer
(polyethylene glycol diacrylate) from Sartomer. FIG. 2 shows the
torque of PP-A and PP-B when reprocessed on a Haake torque
rheometer. PP-B shows higher torque, indicating that the use of
multifunctional monomer decreased vis-breaking during maleation and
that melt strength was increased.
[0043] PP-A and PP-B were blended with varying amounts of
1,3-phenylenediamine (Aldrich) on a Haake type mixer at 230.degree.
C. and 60 rpm for 4 minutes to obtain long chain branching. FIG. 3a
shows torque as a function of time for neat PP-A, PP-A+0.5%
diamine, and PP-A+2% diamine. The addition of 0.5% diamine
moderately increased torque, while 2% diamine increased torque to a
further degree. Increased torque can be indicative of branching or
crosslinking of maleated PP by the diamine coupling agent. FIG. 3b
shows torque as a function of time for neat PP-B, PP-B+0.5%
diamine, and PP-B+0.5% diamine+0.5% KOH. When maleated PP-B was
mixed with 0.5% diamine, the torque increase was relatively more
significant than that of PP-A+0.5% diamine, indicating more
efficient branching and crosslinking of PP-B than PP-A. The use of
multifunctional monomer can decrease PP vis-breaking in the
maleation process and can also result in higher grafting of maleic
anhydride and a more even distribution of maleic anhydride grafts.
The composition of PP-B+0.5% diamine+0.5% KOH combined coupling
reactions with ionic interactions (supplied by the neutralizer
potassium hydroxide). Further increase in torque for this
composition indicates that coupling reactions and ionic
interactions can combine synergistically to enhance melt
strength.
Example D
[0044] High melt strength polypropylenes were prepared and used as
masterbatches for enhancing the melt strength of a polypropylene
homopolymer and a polypropylene impact copolymer. The polymer
compositions were extruded through a Brabender single-screw lab
extruder and measured for sag resistance to characterize their melt
strength.
[0045] The polypropylene homopolymer base resin was Total
Petrochemical 3371, with a 2.8 g/10 min melt flow rate. The high
melt strength polypropylenes included either multifunctional
monomers or ionomers made of maleated polypropylene and
neutralizers, or in one case, both. Table 3 lists the polymer
compositions, shows melt flow rates (g/10 min) for the
masterbatches (MB) and 3371+5% MB, and shows whether sag resistance
was improved or worsened upon addition of 5% MB to 3371. Total
Petrochemicals 3270 is a polypropylene homopolymer. Total
Petrochemicals 4170 is a polypropylene impact copolymer. SR351
(trimethylolpropane triacrylate) and SR259 (polyethylene glycol
diacrylate) are multifunctional monomers from Sartomer.
TABLE-US-00003 TABLE 3 Masterbatch compositions and melt flow rates
and sag results when used with a polypropylene homopolymer. MFR
(g/10 min) Sag Masterbatch Composition Neat MB 3371/5% MB results
3270 + 0.5% SR351 1.2 3.6 0 4170 + 2.0% SR259 1.0 2.9 0 4170 + 0.5%
SR351 0.7 2.6 0 3270 + 3% KOH 3.1 3.2 -- (not really an ionomer)
3270 + 3% ZnAc 3.4 3.4 -- (not really an ionomer) 3270 + 1% MAH +
0.025% L- 0.0 3.1 ++ 101 + 2% KOH 3270 + 2% MAH + 0.05% L- 0.0 3.6
+++ 101 + 2% KOH 3270 + 1% MAH + 0.02% L- 0.2 3.2 +++++ 101 + 1%KOH
3270 + 1% MAH + 0.02% L- 8.3 3.3 -- 101 + 0.5% KOH 3270 + 1% MAH +
0.02% L- 0.6 3.0 ++ 101 + 0.85% KOH 3270 + 2% MAH + 1% SR259 + 1.2
3.3 ++ 0.05% L101 + 2% KOH
[0046] The polymer compositions containing multifunctional monomer
did not show an improvement in sag resistance compared to neat
3371. The ionomers, however, generally improved sag resistance, and
hence, improved melt strength.
[0047] The same masterbatches were also blended with a
polypropylene impact copolymer, Total Petrochemicals 4170, with a
fractional melt flow rate. Table 4 lists the polymer compositions,
shows melt flow rates (g/10 min) for the masterbatches (MB) and
4170+5% MB, and shows whether sag resistance was improved or
worsened upon addition of 5% MB to 4170.
TABLE-US-00004 TABLE 4 MFR (g/10 min) Sag Masterbatch Composition
Neat MB 4170/5% MB results 3270 + 0.5% SR351 1.2 0.88 0 4170 + 2.0%
SR259 1.0 0.80 0 4170 + 0.5% SR351 0.7 0.82 ++ 3270 + 3% KOH 3.1
1.01 0 3270 + 3% ZnAc 3.4 0.96 - 3270 + 1% MAH + 0.025% L- 0.0 0.84
0 101 + 2% KOH 270 + 2% MAH + 0.05% L- 0.0 0.78 0 101 + 2% KOH 3270
+ 1% MAH + 0.02% L- 0.2 0.83 ++ 101 + 1% KOH 3270 + 1% MAH + 0.02%
L- 8.3 0.83 - 101 + 0.5% KOH 3270 + 1% MAH + 0.02% L- 0.6 0.85 -
101 + 0.85% KOH 3270 + 2% MAH + 1% SR259 + 1.2 0.81 0 0.05% L101 +
2% KOH
[0048] As the base resin had a very low melt flow rate, the
masterbatches containing multifunctional monomer were easier to mix
with the base material, relative to mixing with 3371. As a result,
the composition 4170+0.5% SR351 with a fractional melt flow rate
was able to improve the melt strength of 4170. Most of the ionomers
had negligible or even negative effect on 4170 melt strength,
perhaps due to rubber phases in 4170 disrupting the ionic
interactions. Overall, the results show that, in certain cases,
high melt strength polypropylenes prepared with multifunctional
monomers and/or acid neutralizers can be successfully used as
masterbatches for enhancing melt strength of conventional
polypropylenes.
[0049] As used herein, the term "high melt strength polypropylene"
refers to a composition of polypropylene that exhibits enhanced
processability and performance in the molten state, as compared to
neat polypropylene. Mechanical properties of HMS-PP such as
modulus, drawability, and yield strength, for example, may be
higher as compared to neat polypropylene.
[0050] While illustrative embodiments have been depicted and
described, modifications thereof can be made by one skilled in the
art without departing from the spirit and scope of the disclosure.
Where numerical ranges or limitations are expressly stated, such
express ranges or limitations should be understood to include
iterative ranges or limitations of like magnitude falling within
the expressly stated ranges or limitations (e.g., from about 1 to
about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11,
0.12, 0.13, etc.).
[0051] 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.
* * * * *