Note: Descriptions are shown in the official language in which they were submitted.
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
TITLE: REACTIVE CARRIERS FOR POLYMER MELT INJECTION
BACKGROUND OF THE INVENTION
1 ) FIELD OF THE INVENTION
The present invention concerns a reactive cannier that forms no by-products
during melt injection of polymer into articles such as sheets, films, fibers
and containers.
The reactive carrier is used to mix additives into the polymer resin. More
particularly,
the invention relates to the use of one or more cyclic anhydrides or
substituted cyclic
anhydrides as the reactive carrier. The polymer can be polyester or polyamide.
2) PRIOR ART
In many injection molded polymer articles additives are required to improve
the
functionality of the article. Typical additives are colorants, anti-slip
agents, flame
retardants, antioxidants, gas barrier agents, ultraviolet (UV) radiation
absorbers,
acetaldehyde reducing agents, crystallization control agents, fillers and the
like.
A "masterbatch" approach has been used to mix additives into injection molded
polymer articles. In the masterbatch process, the desired additive is
dispersed at a
relatively highly concentrated level within a carrier polymer. In a following
process step,
the masterbatch of highly concentrated additive polymer is blended with virgin
polymer
at the feed throat of the melt extruder. Depending on the quality of the
process control of
the drying and metering of the masterbatch, variations in additive levels and
the polymer
molecular weight can be unacceptable.
An alternative method is to use a liquid dispersion of the additive that is
pumped
at the extruder throat. The liquid carrier must be organic, non-aqueous,
soluble in the
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
polymer and have a boiling point greater than the extrusion temperature, i.e.
generally
above 300° C. Commercial liquid carriers can be obtained from
ColorMatrix
Corporation, Cleveland, Ohio and designated as ColorMatrix LCPY-1: 82-89
Series.
According to the material safety data sheet (MSDS) from ColorMatrix
Corporation, the
main named ingredient is refined hydrocarbon oil.
The problem with the use of liquid carriers is that they can effect the
processing
of the article and remain in the article. For instance they can cause the
extruder screw to
slip, plate out on the molds and can be extracted.
US Patent Nos. 6,569,991, 6,573,359, 6,590,069 and 6, 599, 596 to Nichols et
al.
disclose the use of a reactive carrier that reacts with the condensation
polymer, thereby
binding the reactive carrier in the polymer resin and preventing the emergence
of the
carrier from the polymer resin during subsequent thermal processing. These
patents
show in the Figures the effect of the reactive carrier molecular weight on the
theoretical
loss of molecular weight for condensation polymers as a function of the
concentration of
the reactive carrier (i.e. use of the specified reactive carrier causes a loss
of molecular
weight of the polymer). High molecular weight (less than 10,000 g/mol)
reactive carriers
are preferred, especially polyols and most preferred polyethylene glycols with
a
molecular weight between about 400 and 1000 g/mol.
U.S. Pat. No. 6,342,578 to Huang discloses a polyester with one or more of
phthalic anhydride, glutaric anhydride, benzoic anhydride, malefic anhydride
or succinic
anhydride in an amount sufficient to significantly reduce the caustic stress
cracking. The
anhydrides reacted with the hydroxyl end groups to fore carboxyl end groups
(CEG).
There is a need for reactive carriers that do not reduce the molecular weight
of
the polymer.
2
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
SUMMARY OF THE INVENTION
The inventors have found that cyclic anhydrides, and in particular substituted
cyclic anhydrides can be used as reactive carriers without forming by-products
that
reduce the molecular weight of the polymer.
In the broadest sense, the present invention relates to the use of a liquid
cyclic
anhydride at the time it is injected, as a carrier of additives in a polymer
that is melt
extruder into an article.
In the broadest sense, the invention also comprises a method of injecting a
liquid
cyclic anhydride containing additives into a melt extrusion process. The
anhydride is
liquid at the time of injection.
DETAILED DESCRIPTION OF THE PROCESS
Cyclic anhydrides will react with any nucleophilic group, including hydroxyl,
carboxyl, primary and secondary amines and amides. This means that they are
best
suited as reactive carriers in polyesters and polyamides.
Suitable cyclic anhydrides are those with a melt point of less than that of
the
polyester or polyamide. Preferable are cyclic anhydrides with a melt point
less than
about 160 °C, most preferable are cyclic anhydrides with a melt point
of less than 100
°C, and especially suitable are those that are liquid at room
temperature (25°C).
Polyethylene terephthalate (PET) is conventionally made by reacting either
dimethyl terephthalate or terephthalic acid with ethylene glycol, for example,
via an
esterification reaction, followed by a polycondensation reaction. When making
PET,
either in a batch or continuous process, the reactions can be driven to near
completion,
yielding PET having up to 3 weight percent of diethylene glycol and other
byproducts.
PET is meant to include small amounts of byproducts.
3
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
Conventional continuous production of PET is well known in the art and
comprises reacting terephthalic acid and ethylene glycol at a temperature of
approximately 200° to 250°C forming monomer and water. Because
the reaction is
reversible, the water is continuously removed, driving the reaction to the
production of
monomers and some oligomers. Next the monomers and oligomers undergo
polycondensation reaction in vacuum conditions at a temperature of
approximately 250°
to 290°C to form polyester having an IV of about 0.4 to 0.6. During the
esterification
reaction, no catalyst is needed. However, in the polycondensation reaction, a
catalyst
such as an antimony compound or titanium compound is necessary.
PET is also made in batch and continuous processes from the reaction of the
ester-dimethyl terephthalate and ethylene glycol, at a reaction temperature of
approximately 190° to 230°C forming alcohol (methanol) and
monomer. This
esterification reaction is reversible and the alcohol must be continuously
removed,
driving the reaction to the production of monomer and some oligomer. In the
reaction of
dimethyl terephthalate and ethylene glycol, catalysts such as manganese, zinc,
cobalt or
other conventional catalyst are employed. Next, the monomer and oligomer
undergo a
polycondensation reaction at the conditions stated above to fore polyester or
copolyester
having an IV of about 0.4 to 0.6. Making a copolyester of PET and a
dicarboxylic acid
merely requires the addition of the acid or its ester equivalent, for example,
to also
undergo an esterification (or transesterification) reaction. Making a
copolyester of PET
and a diol merely requires the addition of the diol during esterification (or
transesterification). For use as a bottle resin the polyester or copolyester
from this melt
phase reaction is solid state polymerized by conventional methods to increase
the resin
molecular weight (IV).
Resins containing up to 20 wt % of the dicarboxylic acid are useful in forning
bottles or jar containers as is known in the art. Suitable diacids may be
aliphatic,
alicyclic, or aromatic dicarboxylic acids such as isophthalic acid, 1,4-
cyclohexanedicarboxylic acid; 1,3-cyclohexanedicarboxylic acid, succinic acid,
glutaric
acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid; 2,6-
naphthalenedicarboxylic
acid, bibenzoic acid, oxalic acid, malonic acid, pirnelic acid, suberic acid,
azelaic acid,
malefic acid, fumaric acid, phthalic acid, hemimellitic acid, trimellitic
acid, trimesic acid,
4
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
or mixtures of these and their equivalents. It is often preferred to use a
functional acid
derivative equivalent such as dimethyl, diethyl, or dipropyl ester of the
dicarboxylic acid.
Alternatively, polyester resins may optionally be modified by up to 20 wt % of
one or more different diols than ethylene glycol. Such additional diols
include
cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols
preferably
having 3 to 20 carbon atoms. Examples of such diols to be included with
ethylene glycol
are: diethylene glycol, triethylene glycol, 1,2-cyclohexanedimethanol, 1,3-
cyclohexanedimethanol, 1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-
diol,
pentane-1,5-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4), 2-
methylpentanediol-(1,4),
2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-
diol-(1,3),
hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4-
hydroxycyclohexyl)-
propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-
hydroxyethoxyphenyl)-propane, and 2,2-bis-(4 hydroxypropoxyphenyl)-propane.
Polyamides means polyamides made from the condensation of aliphatic or
aromatic diamines with dicarboxylic acids, or the condensation of lactams. The
preferred
polyamides are nylon 66 and nylon 6.
Article means films, sheets for thermoforming, fibers, and injection molded
parts
in particular preforms for stretch blow molding into containers.
In a preferred embodiment the cyclic anhydride carrier containing additives is
injected into the melt extrusion process. The injection occurs in the melt
piping
conducting the molten polymer to the article forming device, such as film or
fiber
forming machines.
In another embodiment the cyclic anhydride carrier containing additives is
added
at the end of a continuous polymerization process in the transfer pipe between
the final
reactor and the die that forms the strands that are cooled and chipped.
Optionally this
resin can be solid-state polymerized to a higher molecular weight (IV).
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
In the preferred embodiment the cyclic anhydride liquid carrier containing
additives is added into a mixing box at the throat of the extruder of the
preform injection
molding or extrusion blow molding machine. For this process it is preferred
that the
liquid carrier has a melting point near or below ambient temperatures. This
simplifies
the addition of the anhydride into the extruder, as complicated heating
systems are not
required.
For stretch blow molding containers, the preform is heated to about 100 -
120°C
and blown-molded into contour bottle at a stretch ratio of about 12.5. The
stretch ratio is
the stretch in the radial direction times the stretch in the length (axial)
direction. Thus if
a preform is blown into a bottle, it may be stretched about two times its
length and
stretched about six times is diameter giving a stretch ratio of twelve (2 x
6). Since the
bottle size is fixed, different preforln sizes can be used for obtaining
different stretch
ratios.
The preferred carriers are cyclic anhydrides, selected from the following
classes:
a) succinic anhydrides
R
R
R
where R1, R2, R3 and R4 can be hydrogen, alkyl, alkenyl or aryl groups.
Included in this class of succinic anhydrides are cycloalkane and cycloalkene
substituents, giving such compounds as hexahydrophthalic anhydride and
substituted
hexahydrophthalic anhydride:
6
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
Rq
R'
RE
where Rl, R2, R3, R4, RS, R6, R' and R$ can be hydrogen, alkyl, alkenyl or
aryl groups.
Also included in this class are itaconic (2-methylene succinic anhydride) and
substituted itaconic anhydrides:
R'
H2C
O
where R1 and R2 can be hydrogen, alkyl, alkenyl or aryl groups.
From this class, the mono-alkenyl substituted succinic anhydrides are
preferred.
The most preferred are the Cg to C2o alkenyl groups.
a) malefic anhydride
R
R'
7
R, '
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
where Rl and R'' can be hydrogen, alkyl, alkenyl or aryl groups.
Also included in this class are cycloalkane and cycloalkene substituents,
giving
such compounds as 3,4,5,6-tetrahydrophthalic anhydride and substituted
tetrahydrophthalic anhydride groups:
R2
R~
R'
RE
where R1, R2, R3, R4, R5, Rg, R7 and Rg can be hydrogen, alkyl, alkenyl or
aryl groups;
and substituted 1-cyclopentene-1,2-dicarboxylic anhydride:
R4
where R', R', R3, R~, RS and R~ can be hydrogen, alkyl, alkenyl or aryl
groups.
From this class, malefic anhydride and 2-methyl malefic anhydride (citraconic
anhydride) are preferred.
a) glutaric anhydride
8
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
R3
6
where R1, R2, R3, R4, RS and R6 can be hydrogen, alkyl, alkenyl or aryl
groups.
From this class, glutaric anhydride and ~-ethyl-3-methyl glutaric anhydride
are
preferred.
a) diglycolic anhydride
R2
R3
R~
where R1, RZ, R3 and R4 can be hydrogen, alkyl, alkenyl or aryl groups.
a) phthalic anhydride
R'
R
R''
where RI, R'', R3 and R4 can be hydrogen, alkyl, alkenyl or aryl groups.
9
R~ _
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
a) diphenic anhydride
F
R~
Rs
R2
where R', R2, R3, R4, R5, R6, R7 and R$ can be hydrogen, alkyl, alkenyl or
aryl groups.
Table 1 summarizes melting point of selected cyclic anhydrides.
Table 1.
Cyclic anhydride Melting Point (°C)
Succinic anhydride 119-120
methyl succinic anhydride 33-35
2,2-dimethylsuccinic anhydride29-31
phenyl succinic anhydride 53-55
octadecenylsuccinic anhydrideliquid at
RT*
hexadecenyl succinic anhydrideliquid at
RT*
eicosodecenyl succinic anhydrideliquid at
RT*
2-methylene succinic anhydride66-68
n-octenyl succinic anhydride liquid at
RT*
nonenyl succinic anhydride 8-12
tetrapropenyl succinic anhydride14
dodecyl succinic anhydride 40
Glutaric anhydride 55-57
3-methylglutaric anhydride 43-47
phenyl glutaric anhydride 95-99
diglycolic anhydride 92-93
2-ethyl 3-methyl glutaric liquid at
anhydride RT*
3,3-dimethyl glutaric anhydride124-126
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
2,2-dimethyl glutaric anhydride 34-38
3,3-tetramethyleneglutaric anhydride 64-66
Phthalic anhydride 131-134
4-methyl phthalic anhydride 90-92
4-t-butyl phthalic anhydride 70-75
tetrahydrophthalic anhydride 70-74
hexahydrophthalic anhydride 34-38
Malefic anhydride 54-56
2-methyl malefic anhydride 7-8
3,4,5,6-tetrahydrophthalic anhydride 69-73
1-cyclopentene-1,2-dicarboxylic anhydride46-49
dimethyl malefic anhydride 93-96
Biphenyl malefic anhydride 159-162
~ RT means room temperature
For the process where the cyclic anhydride is added at the preform injection
molding stage, low melting points, preferably below 50°C are used. The
preferred cyclic
anhydrides are the alkenyl succinic anhydrides such as octadecenylsuccinic,
hexadecenyl
succinic and eicosodecenyl succinic anhydride, or mixtures thereof.
Additives according to the present invention are colorants, anti-slip agents,
flame
retardants, antioxidants, gas (oxygen and carbon dioxide) barner agents,
oxygen
scavengers, ultraviolet (UV) radiation absorbers, acetaldehyde reducing
agents,
crystallization control agents, impact modifiers, catalyst deactivators, melt
strength
enhancers, anti-static agents, lubricants, chain extenders, nucleating agents,
solvents,
fillers, and plasticizers.
The additives axe mixed with the reactive carrier at the required
concentration for
the functional purpose for which they are used. The preferred reactive carrier
level to be
injected or mixed with the polymer is about 1 wt-% or less (100 ppm -
10,000ppm).
Any additive used with a reactive carrier should not react with the liquid
carrier prior to
the addition to the polymer.
TESTING PROCEDURES
Meltin~P oint
11
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
The melting point of the cyclic anhydrides is measured with a hot stage
microscope. The hot stage is heated rapidly at first and then adjusted to
2°C/min. during
the last 10°C preceding the expected melting point. The melting point
is defined as the
range from the temperature that melting is first observed to that at which
melting is
complete.
IV
Intrinsic viscosity (IV) of the polymer is determined by mixing 0.2 grams of
an
amorphous polymer composition with twenty milliliters of dichloroacetic acid
at a
temperature of 25°C using an Ubbelhode viscometer to determine the
relative viscosity
(RV). RV is converted to IV using the ISO certificated equation:
IV = [(RV -1) x 0.6907] + 0.63096
Haze and Color
The haze of the preforms and bottles was measured with a Hunter Lab
ColorQuest II instrument. The haze is defined as the percent of diffused light
to total
transmitted light. The color of the bottle sidewalls was measured with the
same
instrument, and report in CIE units of L*, a* and b*.
Coefficient of friction
Coefficient of static friction testing using ASTM D1 X94-O1 was carried out on
the bottle sidewalk at room temperature.
Example 1
This example compares the preferred reactive liquid carrier of US 6,569,991,
polyethylene glycol (PEG), to that of the present invention.
12
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
A standard commercial polyester bottle resin (I~oSa 3302, Spartanburg, South
Carolina, USA) was used. PEG with a molecular weight of 400 was obtained from
Union Carbide, Danbury CT, USA. The cyclic anhydride was alkenyl succinic
anhydrides (ASA), a mixture of alkenyl succinic anhydrides from Albemarle
Corporation, Richmond, Virginia, U.S.A. that contains 54 % hexadecenyl, 34
octadecenyl and 10 °Jo eicosodecenyl succinic anhydride
The 3302 resin was dried under vacuum at 150° C for 12 hours. The
dried resin
was blended with the liquid carrier and injected molded into 48 gram prefonns
on an
Arburg injection molding machine.
The preform IV was measured and the results set forth in Table 2.
Table 2
Additive Amount, ppm IV ,
None None 0.743
ASA 2,000 0.748
ASA 4,000 0.741
PEG 2,000 0.680
PEG 4,000 0.625
These results illustrate that the ASA did not cause any IV loss, since it
reacted by
ring opening with no byproduct, compared to PEG which transesterifies with the
polyester resin giving water as a byproduct causing hydrolysis and a loss in
molecular
weight (IV).
The preform color and haze were measured and the results set forth in Table 3.
Table 3
Additive Amount, ppm L* a* B* Haze,
None None 70.5 -0.0 2.1 22
ASA 2,000 70.4 -0.1 2.8 22
ASA 4,000 70.3 -0.2 3.3 23
PEG 2,000 70.5 0.0 2.6 22
PEG ~ 4,000 63.3 0.9 9.6 30
13
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
The ASA liquid carrier had little effect on the color and haze of the prefonn,
in
contrast to PEG which at a level of 4000 ppm significantly increased the
yellowness (b*)
and haze_
Example 2
A mixture of ASA containing 5 wt.-% of a fumed silica, Cab-O-silo M7D (Cabot
Corporation, Boston MA, USA) was prepared by stirring the fumed silica with
the ASA
liquid. Dried 3302 polyester resin was coated with this mixture by mixing in a
bag, and
then injected molded into 48 gram preforms on an Arburg injection molding
machine.
The level of ASA was 4,000 ppm (giving a fumed silica loading of 200 ppm). The
coefficient of friction of the 3302 control was 9.3 compared to 0.2 with the
anti-slip
agent (Earned silica) incorporated into the resin with a cyclic anhydride.
Example 3
The procedure of Example 2 was followed with a mixture of 81.2 wt % ASA and
18.8 wt.-% of an UV absorber, Tinuvin 234 (Ciba Specialty Chemicals, Charlotte
NC,
USA). The level of ASA was 4,000 ppm giving an UV absorber loading of 900 ppm.
The 24 gram preforms were blown into bottles (0.59 liter) on a Cincinnati
Milacron stretch blow molding machine. The UV absorbance of the bottle side
walls
(0.38 mm) was measured. The % transmittance at 370 nm was less than 10% for
the UV
additive bottle compared to 80% for the 3302 control.
Example 4
The procedure of Example 3 was followed using a mixture of 97.5 wt-% ASA
and 2.5 wt.-°J° of a blue dye, Polysynthren Blue RBL (Clariant
Corporation, Charlotte
NC, USA). The mixture was used at a level of 500 ppm. The color and haze of
the
bottle sidewalls was compared with commercial bottles in which the same
concentration
of blue dye was added with a hydrocarbon oil carrier, the results are set
forth in Table 4.
14
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
Table 4
L* a* b* Haze,
3302, control 95.5 0.1 0.7 4.4
ASA carrier 95.2 -0.5 -0.1 4.6
Mineral oil carrier94.8 -0.6 -0.2 4.5
These results show that the cyclic anhydrides can be used to replace
hydrocarbon
oil carriers.
Example 5
A common additive that is used in polyester bottle resin compositions is a
reheat
agent. These reheat agents reduce the time it takes for the preform to heat to
the stretch
blow molding temperature. US Patent No. 5,925,710 discloses the use of
graphite as a
reheat agent.
The procedure of Example 1 was followed to prepare a mixture of 99 wt-% ASA
and 1 wt.-% graphite (Grafitbergbau Kaiserberg AG, I~aiserberg Austria). The
mixture
was used at a level of 1,000 ppm to give 10 ppm graphite in the resin.
In the preform reheat process a series of infra-red lamps are used to heat the
preform to the stretch blowing temperature. By changing the power to these
lamps the
final preform temperature will change. The effect of the lamp power on preform
temperature is set forth in Table 5.
Table 5
of full power Preform Tem erature
C
Graphite, ppm None 10
81 89.3 98.3
84 91.0 100.0
87 93.0 102.7
90 94.0 104.7
93 96.7 105.7
CA 02554228 2006-07-21
WO 2005/076947 PCT/US2005/003685
These results indicate that a cyclic anhydride reactive carrier is an
effective
carrier to add reheat additives to polyester.
Thus it is apparent that there has been provided, in accordance with the
invention,
a polyester or polyamide resin, with a cyclic anhydride and additive, a
process for
making such a resin, a process for making an injected article from such a
resin, and an
injected molded article from such a resin that fully satisfies the objects,
aims, and
advantages set forth above. While the invention has been described in
conjunction with
the specific embodiments thereof, it is evident that many alternatives,
modifications, and
variations will be apparent to those skilled in the art in light of the
foregoing description.
Accordingly, it is intended to embrace all such alternatives, modifications,
and variations
as fall within the spirit and broad scope of the present invention.
16
