U.S. patent application number 13/628536 was filed with the patent office on 2013-01-31 for methods and compositions for inhibiting vinyl aromatic monomer polymerization.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is GENERAL ELECTRIC COMPANY. Invention is credited to Sherif Eldin, H. Kelly Herrington, Mary King, John Link, Vinod Kumar Rai, Alagarsamy A. Subbiah.
Application Number | 20130030225 13/628536 |
Document ID | / |
Family ID | 44626629 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130030225 |
Kind Code |
A1 |
Rai; Vinod Kumar ; et
al. |
January 31, 2013 |
METHODS AND COMPOSITIONS FOR INHIBITING VINYL AROMATIC MONOMER
POLYMERIZATION
Abstract
Methods and compositions are provided for inhibiting the
polymerization of a vinyl aromatic monomer, such as styrene
monomer, during elevated temperature processing thereof or during
storage or shipment of polymer containing product. The compositions
comprise a combination of a quinone methide derivative A) and a
phenol compound B). The methods comprise adding from about 1-10,000
ppm of the combination to the monomer containing medium, per one
million parts of the monomer.
Inventors: |
Rai; Vinod Kumar;
(Bangalore, IN) ; Eldin; Sherif; (Bellaire,
TX) ; King; Mary; (Kingwood, TX) ; Link;
John; (Humble, TX) ; Subbiah; Alagarsamy A.;
(Bangalore, IN) ; Herrington; H. Kelly; (Thicket,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GENERAL ELECTRIC COMPANY; |
Schenectady |
NY |
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
44626629 |
Appl. No.: |
13/628536 |
Filed: |
September 27, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12793226 |
Jun 3, 2010 |
8298440 |
|
|
13628536 |
|
|
|
|
Current U.S.
Class: |
585/5 ; 252/404;
585/3 |
Current CPC
Class: |
C08F 12/08 20130101;
C07C 7/20 20130101; C07C 7/20 20130101; C07C 15/46 20130101; C08F
12/08 20130101; C08F 2/40 20130101 |
Class at
Publication: |
585/5 ; 585/3;
252/404 |
International
Class: |
C07C 7/20 20060101
C07C007/20; C09K 15/08 20060101 C09K015/08 |
Claims
1. A method for inhibiting the polymerization of vinyl aromatic
monomer comprising adding to said monomer an effective
polymerization inhibiting amount of a compound comprising (A) a
quinone methide derivative having the formula ##STR00003## wherein:
R.sub.1 and R.sub.2 are independently H, C.sub.4 to C.sub.18 alkyl;
C.sub.5 to C.sub.12 cycloaklyl; or C.sub.7 to C.sub.15 phenylalkyl,
and R.sub.3 is aryl, or aryl substituted with C.sub.1 to C.sub.6
alkyl, alkoxy, hydroxy, nitro, amino, carboxy, or mixtures thereof;
and (B) a phenol compound having the formula ##STR00004## wherein
R.sub.4 and R.sub.5 may be the same or different and are chosen
from C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.30 alkaryl and
substituted C.sub.1-C.sub.30 alkaryl; R.sub.6 is selected from
C.sub.1-C.sub.20 alkyl, thiophenol, substituted thiophenol,
C.sub.1-C.sub.40 alkanoic acid ester, C.sub.1-C.sub.30 alkaryl,
substituted C.sub.1-C.sub.30 alkaryl, C.sub.1-C.sub.6 alkylamino,
C.sub.1-C.sub.6 alkoxy, amine, polynuclear aryl and substituted
polynuclear aryl.
2. The method as recited in claim 1 wherein the weight ratio of A
to B is about 90:10 to about 10:90.
3. The method as recited in claim 2 wherein said quinone methide
derivative A) is
2,6-di-tert-butyl-4-benzylidene-cyclohexa-2,5-dienone.
4. The method as recited in claim 3 wherein said phenol compound B)
is 2,6-di-tert-butyl phenol.
5. The method as recited in claim 4 wherein from about 1,-10,000
ppm of A and B collectively is brought into contact with said vinyl
aromatic monomer, based on 1 million parts of said vinyl aromatic
monomer.
6. The method as recited in claim 5 wherein said vinyl aromatic
monomer comprises styrene monomer.
7. The method as recited in claim 5 wherein the weight ratio of A:B
is about 70:30.
8. The method as recited in claim 7 further comprising the step of
heating said styrene monomer.
9. The method as recited in claim 7 further comprising the step of
distilling said styrene monomer to remove impurities therefrom.
10. Vinyl aromatic monomer anti-polymerization composition
comprising a liquid carrier and dissolved or dispersed therein A) a
quinone methide derivative having the formula ##STR00005##
wherein:. R.sub.1 and R.sub.2 are independently H, C.sub.4 to
C.sub.18 alkyl; C.sub.5 to C.sub.12 cycloaklyl; or C.sub.7 to
C.sub.15 phenylalkyl, and R.sub.3 is aryl, or aryl substituted with
C.sub.1 to C.sub.6 alkyl, alkoxy, hydroxy, nitro, amino, carboxy,
or mixtures thereof; and (B) a phenol compound having the formula
##STR00006## wherein R.sub.4 and R.sub.5 may be the same or
different and are chosen from C.sub.1-C.sub.20 alkyl,
C.sub.1-C.sub.30 alkaryl and substituted C.sub.1-C.sub.30 alkaryl;
R.sub.6 is selected from C.sub.1-C.sub.20 alkyl, thiophenol,
substituted thiophenol, C.sub.1-C.sub.40 alkanoic acid ester,
C.sub.1-C.sub.30 alkaryl, substituted C.sub.1-C.sub.30 alkaryl,
C.sub.1-C.sub.6 alkylamino, C.sub.1-C.sub.6 alkoxy, amine,
polynuclear aryl and substituted polynuclear aryl.
11. Vinyl aromatic monomer anti-polymerization composition as
recited in claim 10 wherein A) and B) are present in a weight ratio
of about 90:10 to about 10:90.
12. Vinyl aromatic monomer anti-polymerization composition as
recited in claim 11 wherein said quinone methide derivative A) is
2,6-di-tert-butyl-4- benzylidene-cyclohexa-2,5-dienone.
13. Vinyl aromatic monomer anti-polymerization composition as
recited in claim 12 wherein said phenol compound B) is
2,6-di-tert-butyl phenol.
14. Vinyl aromatic monomer anti-polymerization composition as
recited in claim 12 wherein said liquid carrier comprises a
non-polar organic solvent and wherein A) and B) are both dissolved
in said solvent.
15. Vinyl aromatic monomer anti-polymerization composition as
recited in claim 14 wherein said non-polar organic solvent
comprises heavy aromatic naphtha or xylene.
16. Vinyl aromatic monomer anti-polymerization composition as
recited in claim 10 further comprising styrene monomer.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application is a divisional of allowed U.S.
patent application Ser. No. 12/793,226 filed Jun. 3, 2010.
FIELD OF THE INVENTION
[0002] The invention pertains to methods and compositions for
inhibiting the undesired polymerization of vinyl aromatic monomers,
such as styrene monomer, during processes such as monomer
preparation, and purification, and during storage and shipment of
products containing such monomers.
BACKGROUND OF THE INVENTION
[0003] Polystyrene is a thermoplastic with many desirable
characteristics. It is clear, transparent, readily colored and
easily fabricated. The family of styrene polymers includes
polystyrene itself, copolymers of styrene with other vinyl
monomers, polymers of derivatives of styrene and mixtures of
polystyrene and styrene-containing copolymers with elastomers.
[0004] ABS (acrylonitrile, butadiene-styrene) resins have enjoyed
tremendous commercial popularity for many years as durable,
temperature and solvent resistant elastomers. On the other hand,
styrene plastics are commonly used for packaging, including foams
and films, coatings, in appliance fabrication, for housewares and
toys, lighting fixtures and in construction materials.
[0005] It is well known that styrene monomer readily polymerizes
when heated or exposed to light. Heat polymerization is rapid. In
fact, polymerization increases with increasing temperature. This
polymerization is undesirable during many stages of the
manufacturing, processing, handling, storage and use of styrene
monomers.
[0006] Common industrial methods for producing styrene include a
variety of purification processes, including distillation, to
remove impurities. Unfortunately, purification operations carried
out at elevated temperatures result in an increased rate of
undesired polymerization. Polymerization, such as thermal
polymerization, during the monomer purification process, results
not only in loss of desired monomer end- product, but also in loss
of production efficiency caused by polymer formation or
agglomeration on process equipment. In heat requiring operations,
such agglomeration adversely affects heat transfer efficiency.
SUMMARY OF THE INVENTION
[0007] In accordance with aspect of the invention, a method is
provided for inhibiting the polymerization of a vinyl aromatic
monomer such as styrene monomer, i.e., ethylbenzene. The method
comprises adding an effective polymerization inhibiting amount of a
combined treatment to the monomer medium. The combined treatment
comprises (A) a quinone methide derivative and (B) a phenol
compound. From about 1-10,000 ppm of (A) and (B) collectively is
brought into contact with the requisite vinyl aromatic monomer
based on 1 million parts of the monomer. The method may, in other
aspects of the invention, comprise the step of heating the monomer
and, in another aspect of the invention, the monomer may be
distilled to remove impurities therefrom.
[0008] In another aspect of the invention, a vinyl aromatic monomer
anti-polymerization composition is provided which comprises a
liquid carrier and dissolved or dispersed therein (A) a quinone
methide derivative and (B) a phenol compound.
[0009] In another embodiment, the quinone methide derivative is
2,6-di-tert- butyl-4-benzylidene-cyclohexa-2,5-dienone.
[0010] In another aspect of the invention, the phenol compound (B)
is 2,6-di-t-butylphenol.
[0011] In another exemplary embodiment, a liquid carrier such as a
non-polar organic solvent is provided with the combined treatment
(A) and (B) dissolved or dispersed therein.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0012] In accordance with the invention, both a quinone methide
derivative A) and a phenol compound B) are conjointly utilized to
inhibit polymerization of a vinyl aromatic monomer such as
styrene.
[0013] The quinone methide derivatives generally have the
formula:
##STR00001##
wherein:
[0014] R.sub.1 and R.sub.2 are independently H, C.sub.4 to C.sub.18
alkyl; C.sub.5 to C.sub.12 cycloalkyl; or C.sub.7 to C.sub.15
phenylalkyl.
[0015] Preferably, R.sub.1 and R.sub.2 are tert-butyl, tert-amyl,
tert-octyl, cyclohexyl, .alpha.-methylbenzyl or
.alpha.,.alpha.-dimethylbenzyl; with tert-butyl, tert-amyl or
tert-octyl most preferred.
[0016] R.sub.3 is preferably aryl, or aryl substituted with C.sub.1
to C.sub.6 alkyl, alkoxy, hydroxy, nitro, amino, carboxy, or
mixtures thereof.
[0017] Means for preparing these compounds may be found in U.S.
Pat. No. 4,032,547, the contents of which are wholly incorporated
by reference to herein.
[0018] Preferably, the quinone methide derivative is
2,6-di-tert-butyl-4- benzylidene-cyclohexa-2,5-dienone.
[0019] The phenol compounds B) that may be utilized generally have
the formula:
##STR00002##
wherein R.sub.4 and R.sub.5 may be the same or different and are
chosen from C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.30 alkaryl and
substituted C.sub.1-C.sub.30 alkaryl, R.sub.6, when present, is
selected from C.sub.1-C.sub.20 alkyl, thiophenol, substituted
thiophenol, C.sub.1-C.sub.40 alkanoic acid ester, C.sub.1-C.sub.30
alkaryl, substituted C.sub.1-C.sub.30 alkaryl, C.sub.1-C.sub.6
alkylamino, C.sub.1-C.sub.6 alkoxy, amine, polynuclear aryl and
substituted polynuclear aryl.
[0020] At present, the preferred phenol B) compound is
2,6-di-t-butylphenol. Exemplary phenols include 2,6-dipropylphenol,
2,6-diethylphenol and 2,6-dimethylphenol. Also mentioned as
exemplary are the hindered phenols in accord with the above formula
wherein R.sub.4, R.sub.5 and R.sub.6 are all present. These
include: [0021] 2,6-di-t-butyl-4-methylphenol [0022]
4,4'-thiobis-(6-t-butyl-2-methylphenol) [0023] octadecyl
3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate [0024]
4,4'-methylenebis(2,6-di-t-butylphenol) [0025]
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene
[0026] 2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol [0027]
2,6-di-t-butyl-4-secbutylphenol [0028]
2,2'-methylenebis(4-ethyl-6-t-butylphenol) [0029]
2,2'-methylenebis(4-methyl-6-t-butylphenol) [0030]
2,2'-methylenebis(6-(1-methylcyclohexyl)-p-cresol; and [0031]
2,2'-methylenebis(4-methyl-6-cyclohexylphenol)
[0032] The compositions of the present invention are effective at
inhibiting polymerization of vinyl aromatic monomers under
processing conditions. These processing conditions include but are
not limited to preparation, purification, distillation and vacuum
distillation processes.
[0033] Styrene, for example, is typically processed at temperatures
between 95.degree. C. and 125.degree. C. The compositions of the
present invention are effective at inhibiting the polymerization of
styrene over this range of temperatures.
[0034] The vinyl aromatic monomers that are treated by the
compositions of the present invention include but are not limited
to styrene, bromostyrene, divinylbenzene, and
.alpha.-methylstyrene. The compositions of the present invention
are particularly efficacious at inhibiting the polymerization of
styrene monomer.
[0035] The total amount of quinone methide derivative A) and
phenolic compound B) used in the methods of the present invention
is that amount which is sufficient to inhibit polymerization of
vinyl aromatic monomers. This amount will vary according to the
conditions under which the vinyl aromatic monomer is being
processed, contaminants in the system and the temperature of the
system. At higher processing temperatures and higher monomer
contamination, larger amounts of the inhibiting composition are
required.
[0036] For purposes of the present invention, the term "effective
inhibiting amount" is that amount which is effective at inhibiting
vinyl aromatic monomer polymerization. Preferably, this amount
ranges from about 1 part to about 10,000 parts of quinone methide
derivative and phenolic compound, collectively, per 1 million parts
of monomer. Most preferably, this amount will range from about 1 to
1,000 parts per million parts monomer.
[0037] Accordingly, it is possible to produce a more effective
vinyl aromatic monomer polymerization inhibiting treatment than is
obtained by the use of either compound by itself when measured at
comparable treatment levels. This synergism or enhanced activity
between components allows for the concentration of each of the
components to be lowered and the total quantity of polymerization
inhibitor required, particularly at higher temperatures, may be
lowered while achieving a commensurate level of polymerization
inhibition.
[0038] As such, the weight ratio of quinone methide derivative to
phenolic compound will generally range from about 90:10 to about
10:90. Most preferred is a weight ratio of about 70:30.
[0039] The compositions of the present invention can be introduced
into the vinyl aromatic monomer by any conventional method at any
point of the processing system, either as separate and individual
ingredients or as a combination of ingredients.
[0040] The compositions of the present invention may be added to
the vinyl aromatic monomer as either a dispersion or as a solution
using a suitable liquid carrier or solvent. Any solvent that is
compatible with the individual ingredients of the composition and
the vinyl aromatic monomer to be treated may be employed. It is
often desirable to dissolve the inhibitors in the monomer to which
the inhibitor is being added to avoid introducing additional
impurities in the monomer. Exemplary liquid carriers include
non-polar organic solvents, such as heavy aromatic naphtha and
xylene.
[0041] The method of the present invention can control the fouling
of processing equipment, such as the equipment used in separation
and purification processes of styrene monomer, which is due to or
caused by the polymerization of the monomer. The instant invention
may be used as both a process inhibitor, which is employed during
preparation and processing (e.g., employing heat) of the styrene
monomer (i.e., ethylbenzene), and as a product inhibitor, which is
combined with the styrene monomer in order to inhibit
polymerization during storage and handling.
[0042] The invention will now be described in conjunction with the
following examples which should be viewed as being illustrative of
the invention and should not be deemed to limit the invention in
any manner
EXAMPLES
[0043] The effect of a combined treatment of QM (Quinone Methide)
and 2,6-di-tert butyl phenol on the thermal polymerization of
styrene at 115-120.degree. C. was evaluated by comparing polymer
formation utilizing the following procedure.
[0044] A 250 ml RB flask-equipped with an Ar gas inlet, water
cooled condenser and sample outlet was charged with 110 ml of
styrene and the candidate polymerization inhibitor(s). [600 ppm
(w/v)]. The flask was purged with Argon for 10 minutes. The flask
was then immersed into an oil-bath thermostatically controlled at
115-120.degree. C. and heated with purging Ar continuously. Once
the temperature reached 115.degree. C., the stop clock was started
and this time was considered as time zero. About 5 ml of the sample
was removed from the flask at varying time intervals for up to 4
hours and measured precisely before pouring into about 40 ml
methanol to precipitate out the styrene polymer. The precipitated
polystyrene was filtered with a gas membrane filter that was
pre-weighed before use. The polymer was dried at 100.degree. C. and
weighed.
[0045] Styrene Polymerization Results are Shown in Table 1.
TABLE-US-00001 TABLE I Amount of polystyrene formation at
115-120.degree. C. as a function of time for a resultant retarder
dosage of about 600 ppm with different ratios of 2,6-tertiary butyl
phenol (DTBP) and QM. Polymer wt. in mg QM + 2,6- QM + 2,6- QM +
2,6- QM + 2,6- QM + 2,6- QM + 2,6- QM DTBP DTBP DTBP DTBP DTBP DTBP
Time in (pure) (569.3 ppm: (479.98 ppm: (450.24 ppm: (420.22 ppm:
(387.3 ppm: (300.07 ppm: minutes 600 ppm 31.68 ppm) 119.07 ppm)
149.94 ppm) 180.45 ppm) 210.78 ppm) 298.71 ppm) 60 19.58 15.80
12.60 10.1 6.8 13.60 16.20 120 42.85 34.90 24.80 23.2 15.0 29.00
34.50 180 70.75 59.00 41.10 40.1 26.4 50.30 58.60 240 105.85 89.20
60.60 60.5 40.0 76.20 90.30 QM 100.00 94.73 80.12 75.02 69.96 64.76
50.11 (%) 2,6- 0.00 5.27 19.88 24.98 30.04 35.24 49.89 DTBP (%)
[0046] While we have shown and described herein certain embodiments
of the invention, it is intended that these be covered as well as
any change or modification therein which may be made without
departing from the spirit and scope of the invention as defined in
the appended claims.
* * * * *