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Patent 1121829 Summary

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(12) Patent: (11) CA 1121829
(21) Application Number: 330860
(54) English Title: CONTINUOUS MANUFACTURE OF ALLYL DIGLYCOL CARBONATE
(54) French Title: PRODUCTION EN CONTINU DE DIGLYCOLALLYLCARBONATE
Status: Expired
Bibliographic Data
(52) Canadian Patent Classification (CPC):
  • 260/466.8
(51) International Patent Classification (IPC):
  • C07C 69/96 (2006.01)
  • C07C 68/00 (2006.01)
  • C07C 68/02 (2006.01)
(72) Inventors :
  • ANGLE, JAMES R. (United States of America)
  • WAGLE, UDAY D. (United States of America)
  • REID, DONALD C. (United States of America)
(73) Owners :
  • ATOCHEM NORTH AMERICA, INC. (United States of America)
(71) Applicants :
(74) Agent: BORDEN LADNER GERVAIS LLP
(74) Associate agent:
(45) Issued: 1982-04-13
(22) Filed Date: 1979-06-29
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
920,759 United States of America 1978-06-30

Abstracts

English Abstract



-I-
ABSTRACT OF THE INVENTION
A continuous process for the manufacture of allyl
diglycol carbonate (ADC) from diethylene glycol bis-chloro-
formate (Bis CF), allyl alcohol (AA) and alkali metal hydroxide
produces a pure product of good quality, high yields and high
throughput per unit volume of the reactor, The invention
allows the recycle of an aqueous alcohol waste solution in
a concentration below the azeotropic point by simple dis-
tillation by employing a more concentrated alkali metal
hydroxide and an allyl allele aqueous solution. The process
comprises at least two reaction zones, a continuous physical
separation zone for separating the high purity product and a
distillation column for reclaiming the aqueous allyl alcohol
solution below the azeotropic concentration.


Claims

Note: Claims are shown in the official language in which they were submitted.



- 21 -
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An improved process for the continuous
manufacture of allyl diglycol carbonate of the general
formula:

Image

wherein:
(a) R1 is an aliphatic diradical;
(b) R2 is an unsaturated aliphatic radical; and
(c), n is an integer of 1 to 3;
which comprises:
(I) continuously reacting a bis-chloroformate having
the general structure

Image with an alcohol having the
formula R2OH in the presence of an aqueous alkali metal
hydroxide in at least two reaction zones of intense mixing
connected in series at a temperature range of about -5°C
to +60°C and a pH of greater than 7, wherein the first
reaction zone is maintained in the lower part of the



- 22 -
temperature range and the second and subsequent reaction
zones are progressively maintained in the upper part of the
temperature range;
(II) continuously recovering the allyl diglycol
carbonate product by
(i) continuously feeding the reaction mixture
directly from the last reaction zone through a
liquid-liquid separation zone;
(ii) continuously subjecting the product stream
from the liquid-liquid separation zone to a
countercurrent gas stripping zone maintained
at a temperature of from 50 to 150°C and a
pressure of 5 mm of Hg to atmospheric
pressure with the product being removed from
the bottom of the stripping zone;
(iii) continuously removing the gas stream from
the stripping zone, condensing and distilling
the condensate to reclaim the allyl alcohol;
and
(iv) continuously adding the bis-chloroformate,
aqueous alkali metal hydroxide and a portion
of the reclaimed allyl alcohol or pure allyl
alcohol to the first reaction zone to replace



that used up in the reaction effluent.
2. The process of Claim 1 wherein the throughput
per unit volume in the system is 30 to 80 parts by weight per
hour.
3. The process of Claim 1 wherein R2 is allyl.
4. The process of Claim 1 wherein R2 is methyl allyl.
5. The process of Claim 1 wherein R1 is ethylene.
6. The process of Claim 1 wherein R1 is propylene.
7. The process of Claim 1 wherein the reaction zones
have a liquid depth to reaction diameter ratio of 1 to 2 and
the intense mixing is provided by an impeller with tip speed of
at least 1,000 feet per minute and a power input in the range of
50 to 200 horsepower per 1,000 gallons.

23


Description

Note: Descriptions are shown in the official language in which they were submitted.


18~9




Continuous Manufacture of AIIY _iqlYCol Carbonate
(IR 2341)




Backqround of the Invention
Field of the Invention
s The present invention relates to a process and
apparatus for the continuous manufacture of allyl diglycol
carbonate ~ADC) in high purity and at high throughput per
unit reactor volume.

'

8~9
~,
- 2 -



State of the Prior Art
Allyl diglycol carbonate,



(CH2=CH-cH2-O-C-O-CH2-cH2 ) 2 ~


S has gained considerable importance as the preferred monomer
for use in preparation of hard safety lenses and plastic sheets
which are scratch resistant and tough. Certain important
requirements for these end uses are that the monomers be
obtained in high purity, consistent in quality and low in
10 chlorides and volatiles. Variations in quality, especially
viscosity, between lots can lead to a high rejection rate of
polymerized cast sheets and lenses. High chloride content
ln starting monomer will impart a tint to the finished article
on storage.
An example of the prior art is U, S. Patent No. 2, 370, 569
which describes a batch process for making allyl diglycol
carbonate This batch process, however, is subject to
variations from batch to batch. Since the preparation of
ADC is a highly exothermic reation, a number of difficulties
20 arise in the batch preparation thereof. The reaction mass is
often viscous which further decreases the efficiency of heat
transfer surfaces. To improve the heat loss from reaction



. .`

~ ;~18~
-- 3 --



mass to cooling fluid, the temperature of the cooling fluid
may be reduced. It may not be lowered, however, below the
freezing point of the bis-chloroformate and the allyl alcohol
solution (about -8~C) or that of the caustic; if the temperature
5 is lowered, a solid phase appears on the cooling surfaces
reducing the efficiency. If higher reaction temperatures are
used, the relative yield of side reactions are also increased.
' This too leads to impure product or lower yields. Higher
temperatures can also increase the rate of ionic polymeriza-
10 tion of the monomer. Hence, because of the above-men-
tioned problems, the optimum reaction designed for batch
operations involves the use of large heat tran~fer areas.
This is a good solution for small scale operations. However,
for large scale commercial reactors, i. e., about 1, 000
15 gallons, the available tank surface for heat removal increases
less rapidly than the heat load. The additional heat transfer
area is provided as coils that impede the flow of viscous
reaction mass over surface of other coils. The effectiveness
of the heat transfer surfaces decrease as the number of coils
20 is increased. Another possible alternatlve is to lengthen
the reaction period; this leads to a low monomer yield also.


i8;~9

-- 4 --



The present invention overcomes the problems with
batch processes of batch to batch variation, poor monomer
yield on large scale" cyclic var~ation and heat load and need
to handle larger quantities of obnoxious and potentially
5 harmful raw materials9 by providing a continuous flow of
reactants and product throughout the process. The invention
allows the recovery of the excess allyl alcohol in a concen-

' tration below the azeotrope of the alcohol water mixture,
72. 3% by weight alcohol, for recycle to the reaction zone
10 without a complicated alcohol recovery system such as anextractive or azeotropic distillation. A single simple dis-
tillation column is employed to recover most of the excess
allyl alcohol in an aqueous solution used in manufacture of
the ADC. The apparent disadvantage ln contlnuous processes
lS of diluting raw materials with the product which results in
lower reactant concentration should lead to lower reaction
rates and yield of product. In the instant lnvention,
however, this is not the case. On the contrary, it has been
found that in practice the yield of product per unit volume
20 of reactor is substantially higher in the continuous process
than in the batch process.
Another advantage of the present invention is the
recycle of the allyl alcohol in a diluted form. The reaction


~ lBZ'3




to the formation of ADC favors a molar excess of alcohol
that is later removed in the puriEication process. This
diluted alcohol stream from the purification process and
aqueous waste stream from the reaction procedure pose a
5 disposal problem since no simple method of alcohol recovery
exists In a batch process, recycle of recovered allyl alcohol
containing appreceable (30-60%) quantity of water would
lead to hydrolysls of bis-chloroformate, and, as a conse-
quence, higher impurity levels in the product and low yield.
10 In the continuous process, since water iB belng added with
alkali metal hydroxide all the pure recycle of this water-
alcohol stream is acceptable. The present ln~ention
utilizes a simple alcohol recovery technique which allows
recycle of the aqueous alcohol stream. By recovering the
15 alcohol for reuse, the environmental problems of disposal of
a toxic chemical is eliminated
Summary of the Invention
The present invention concerns an improved process
for the continuous manufacture of allyl diglycol carbonate

20 of the general formula:
O O
R~-O-c-~ORl)n-oc-o R2 '
.~ .
.



ii

wherein:
(a) Rl is an aliphatic diradieal such as ethylene or
propylene;
(b) R2 is an unsaturated aliphatic radical sueh as allyl
or methallyl; and
(c) n ls an integer of 1 to 3;
which comprises:
(I) eontinuously reaeting a bis-chloroformate having the
general structure:
0 0
.11 11
Cl-C - (OR1)n-O -C-Cl,

with an alcohol having the formula R2OH in the presence
of an alkali metal hydroxide in at least two reaction zones
of intense mixing conneeted in series at a temperature
range of about -5C to +60C and a pH of greater than 7,
wherein the first reaetion zone is maintained in the lower
part of the temperature range and the seeond and subse-
quent reaetion zones are slightly higher in temperature
than the progressively maintained first reaetion zone.
20 (II) continuously reeovering the allyl diglyeol carbonate
product by
(i) continuously feeding the reaction mixture directly

~ I





from the last reaction zone through a liquid-liquid
separation zone;
(ii~ continuously subjecting the product stream from the
liquid-liquid separation zone to a countercurrent gas
S stripping zone maintained at a temperature of from 50
to 150C and a pressure of 5 mm of Hg to atmospheric
pressure with the pure product being removed from the
bottom of the stripping zone;
(iii) continuously removing the gas stream from the
stripping zone, condensing and distilling the con-
densate to reclaim the allyl alcohol; and
(iv) continuously adding the bis-chloroformate, aqueous
alkali metal hydroxide and a portion of the reclaimed
allyl alcohol or pure allyl alcohol to the first reaction
zone to replace that used up in the reaction effluent.
The product obtained from the stripping column contains at
least 88% of the product monomer. The aqueous solution of
allyl alcohol that is recycled to the first reaction zone is
reclaimed by continuously subjecting the dilute alcohol
stream to a distillative unit maintained at a temperature
from 20 to 100C and a pressure of 25 mm of Hg to atmo-
spheric pressure. The recycle stream from the overhead of
the alcohol recovery column contains between 40% by weight

82'~



to just below the azeotropic concentration of alcohol.
Detailed DescriPtion of the Invention
It has now been discovered that allyl diglycol
carbonate can be continuously produced at a high throughput
5 per unit reactor volume, safeLy and in high purity in an
efficient process by employing at least two intensely mixed
reaction zones and physical separation units such as a
liquid-liquid centrifuge and stripping columns to isolate pure
product and allow the recycle of the excess allyl alcohol.
10 The ADC is generated by continuously reacting a bis-chloro-
formate, an alkali metal hydroxide and a pure or aqueous
solution of a mono-hydric unsaturated alcohoi in at least
two reaction zones of intense mixing in a temperature range
of -5 to +60C and a pH greater than 7,
The invention will be better understood by reference to
the drawing. The accompanying drawing is a schematic plan
view of one form of apparatus suitable for practicing this
invention.
The reactants are continuously added from storage
20 tanks (2, 4 and 6) at controlled fLow rates via metering
devices (8, 10 and 12) to first reactor (14j. The diagram
shows the recycled alcohol stream 59 belng added to the
pure alcohol in storage tank 4. However, it can be stored



_ 9 _




and added to the reactor separately, The concentration of
caustic and the start-up are modified to provide the same
concentrations of water in feed and in reactor as those where
no recycled alcohol is used. A major portion of the reaction
5 (normally 60 to 95%) conversion of the bis-chloroformate
takes place in reactor (14) with the temperature of the reaction
mixture being maintained within + 1C of that desired (normally
-5 to 15C). The reaction mixture from reactor (14) then
flows continuously to the second reactor (16) where a minor
10 portion of the reaction occurs and where the temperature is
between -5 to +15C, preferably maintained at about 5 to
15C, since slight heating occur~ during the intense agitation
and from reaction exotherm, Although two reactors are
sufficient to substantially complete the reaction, the embodi-

15 ment in the drawing is provided with three reactors to increaseresidence time or to reduce residual chlorides in the organic
phase below a specified maximum, Hence, the reaction
mixture from reactor 16 then flows continuously to the third
reactor 18 where the remainder of the reaction occurs at a
20 temperature between +5 and 30C, preferably in the range
of 10-20C. Each of the reactors (14, 16 and 18) is
provided with efficient agitation means (5J 9 and 11)
respectively to insure thorough mixing of the reactants and


11;~18'~9

-- 10 --

cooling means (15, 17 and 19) to remove the heat of reaction,
heat of the alkali metal hydroxide dilution and heat added due
to the intense agitation. The diagram shows the method of
heat removal as acketed cooling, although, any suitable
S method of heat removal may be employed such as coils,
external heat exchangers, etc. In order to distribute the
heat load more evenly, the alkali metal hydroxide may be fed
into two or more reactors such as from storage tank 7 through
metering device 13 to reactor 16. Reactor 16 is also equipped
10 with a pH meter (3) to regulate the pH of the reaction mixture
in the range of 8 to 14 and preferably ~10. Such a system
insures the complete conversion of the bis-chloroformate to
the desired carbonate product and is important since the
- mono-hydric unsaturated alcohol may contain water, thereby
15 improving the product quality and yield considerably. The
system also achieves excellent temperature control resulting
in consistent product quality and improved safety.
The reaction mixture from reactor 18 may contain salts
as a solid phase. In that instance, water is added to
20 dissolve the salts in dissolving means 20 that has agitating
means 21 therein, If, on the other hand, the starting caustic
is dilute, it is not necessary to add water; the reaction mass
can be sent directly to the liquid-liquid separation unit 22





This flow determinatlon is regulated by the two-way valve 12.
Hence, the reaction mixture from reactor 18 is sent either to
dissolving means 20 or directly to liquid-liquid separation
unit 22. Hence, the reaction mixture from reactor 18 is then
5 continuously fed through separation unit 22 such as a liquid-
liquid centrifuge or a gravity settling unit where the product
is separated as stream 40 as the organic phase; the aqueous
stream 41 transferred to holding vessel 44 for recovery. The
organic phase 40 is then treated countercurrently with steam
10 or an inert gas or vapor (e. g. nitrogen) under reduced pres-
sure in a stripping column 24. The column 24 is a conven-
tional column containing plates or packing with either
counter-current or crosscurrent movement of the stripping
medium 25 to the crude product stream 40. The volatile
15 components of the organic phase 40 which include excessive
reactant alcohol and reaction by-products are removed with
the carrier` gas or vapor via line 34 to a suitable condenser
26. When steam is used as the carrying gas it is also con-
densed in 26. The pressure in the column is maintained at
20 the desired low value by a vacuum pump 49 or other suitable
means such as steam ejectors. The overhead condensate
from 26 is sent to a liquid-liquid separation unit 45 where
a separation of the organic and aqueous phase is made.


z9

-- 12 --



The organic phase contains mainly diallyl carbonate (DAC)
formed during the ADC reaction along with allyl alcohol.
Employing steam during stripping leaves an aqueous phase
46 containing allyl alcohol which is transferred to holding
5 vessel 44 for recovery. The pure desired product ls removed
via 30 to a storage means that may be cooled. The tempera-
ture range in the stripping column is normally in the range of
50 to 150C. The operating pressure in the column is
maintained between 5 mm of Hg to atmospheric pressure,
preferably 20 to 150 mm of Hg absolute,
The organic stream 47 from the overhead is sent to a
recovery unit 4~ for recovery of the allyl alcohol and the
reaction by-product diallyl carbonate.
Recovery of the dilute solution of allyl alcohol and
15 water is undertaken in column ~2 from holding vessel 44.
The aqueous alcohol stream is heated to the desired tempera-
ture by heat exchanger 51 and fed to a conventional dis-
tillation column 52 containing plates or packing. ~ost of
the allyl alcohol is recovered as an aqueous solution in the
20 overhead of the distillation column 52 in the concentration
of 40% to slightly below the azeotropic concentration, The
constant boiling mixture is 72. 3% by weight allyl alcohol
at atmospheric pressure. The alcohol rich stream exits


~1~18~'~



through the top of the column and is condensed in heat
exchanger 54 and collected in holding vessel S6. Part of
the aqueous-alcohol stream is recycled to the column through
line 58 while the remainder of the liquid contained in 56 is
5 recycled in stream 59 back to holding tank 4 for reuse in the
manufacturing procedure. The diagram of the invention shows
the recycle stream being added to the pure alcohol stream,
however, this does not have to be the case. An individual
holding tank containing the aqueous alcohol stream along
10 with a meterins device may be desired to more accurately
control the amount of alcohol being added to reactor (14)
since during the initial process ~tart up the concentration of
the alcohol will be changing before equilibrium conditions
are established. A reboiler 60 is included at the base of
15 the alcohol recovery column to add heat to establish a vapor
flow through the stripping section of the column. Stream 64
is continuously withdrawn and discarded. Typically this
stream may contain from 0. 5 to 0. 005% by weight alcohol
depending on the number of theoretical stages contained in
20 the distillation column.
The bis-chloroformate used in the instant process
should have an assay of at least 98. 0% preferably at least
99%. ~ow assaying chloroformates may be used if an


~ 18291

-- 14 --

lnferior quality ADC is acceptable. Alkali metal hydroxide
or potassium hydroxide solutions assaying at about 10 to
50% and preferably 30-50% by weight are desired as the ,
starting materials. The allyl alcohol should have an assay
5 of 97% and preferably 99% pure in the undiluted concentra-
tion. Generally, the reactants are mixed in the ratio of 24
moles of alkall metal hydroxide to 25 moles of alcohol to
10 moles of bis-chloroformate. The molar ratio may be
slightly different for optimum operating conditions depend-

10 ing on the allyl diglycol carbonate being synthesized. Thestripping medium can be steam, nitrogen or other inert
gases, but it is preferable to use steam because steam
allows high capacity with a small vacuum pump and reduced
costs. Conventional centrifuges of either the basket, bowl
15 or disc type can be employed in the system. The centrifuge
used ln the examples infra ls the liquld-liquid centrifuge of
the desludging disc type.
In order to carry out the ADC reaction in an efficient
manner and to insure complete conversion of the chloro-

20 formate, lt is necessary to bring the aqueous and organicphase into intimate contact by intense agitation of the
reaction mixture in the reaction zones. This intense
egitatlon resul~s ID the modiEication oi the reaction mass.




-- 15 --

An added advantage of this intense mixing is the enhance-
ment of the heat transfer rate from the aqueous organic
system to the coolant in the coil and jacket, Hence,
efficient dissapation of the heat of reaction with conse-
quently improved temperature control and safety of operation
are provided for in this invention.
The types of impellers that can be used for the
intense agitation are a flat blade turbine, a pitch blade
turbine or a marlne type propeller. The size of the reactor
and the dimensions of the impeller determine the speed of
agitation. For example, in a ten gallon reactor of standard
configuration wherein liquid depth to reactor diameter ratio
equals 2 to 1, if the diameter of the impeller is 4 to 5
inches, 1, 000 to 1, 400 revolutions per minute (RPM) give
sufficient agitation. Conventional agitation would provide
for up to 5 horse power (HP) per 1, 000 gallons. In the
present invention, by using a reactor of standard config-
uration, it has been found that an impeller tip speed of at
least 1, 000 feet per minute and a power input in the range
of 50 to 200 horse power per 1, 000 gallons is necessary to
provide the intense mixing for high conversion and fast
reaction,

29

-- 16 --



The arrangement of the reactors and the feed system
enables independent control of the raw material flow rates
into the reactor Also, in the reactors, the products of
reaction themselves serve as a heat sink for the heat
5 generated by the reaction. By the efficient deployment of
heat transfer surfaces in the present system, heat is
immediately absorbed from the system. Such an arrange-
ment significantly improves the production capacity (through-
put per unit volume of reactor) of the reactor system over
lO the ones of the prior art. By the judicial choice of the
reactant concentrations in the first reaction zone, the con-
version of the chloroformate to the ADC can be promoted
while simultaneously minimizing chloroformate hydrolysis,
Ieading to high yield of product based on chloroformate
15 consumed; thus making the present process commercially
attractive.
The following examples are set forth to merely
illustrate the invention but are not intended to limit the
practice of this invention thereto. Flow rates are in parts
20 by weight per hour (pph) unless otherwise indicated.


-- 17 --

Example I
Diethylene glycol bis-chloroformate, allyl alcohol
and 40% aqueous caustic soda were continuously added to
reactor (14) at the rates of 136. 7 gm/min (18. 1 pph), 85. 8
gm/min (11. 3 pph) and 88. 6 gm/min (11. 7 pph), respectively.
Simultaneously 30% aqueous caustic soda was added to
reactor 16 at 71. 2 gm/min (9. 4 pph). The temperatures in
the reactors were maintained in the range of 0-5C and
only on an occasion were outside this range. Organic
10 stream (40) from separator flow at the rate of 166. 9 gm/min
(22. 1 pph) and contained 129. 6 gm/min (17. 1 pph) of ADC
monomer. This represents a 79. 8% yield based on the bis-
chloroformate. Chloride levels in the final product were
- 11-14 parts per million. Good product quality including
15 monomer content would be obtained after stripping,
ExamPle 2
For comparative purposes a batch operation of the
prior art was run. In this batch reaction, 40. 2 lbs. of
bis-chloroformate and 25. 3 Ibs. of allyl alcohol were
20 mixed in the reactor. To this 41. 8 Ibs. of 40% NaOH was
added maintaining the temperature in the range 0-5C.
The reaction mass was stirred for another 15 minutes for
the completion of reaction, After stirring, water was added

8~'9

- 18 -



to dissolve the salts and the or~anic phase was separated
and assayed from the aqueous phase after settling. The
yield was 79 8% basedon the bis-chloroformate. Total
time to complete the reaction was approximately 170
5 minutes. It was determined that each gallon of reactor
volume produced 0. 84 lbs. of ADC monomer per hour. The
worlc was conducted in a reactor with an effective volume
of 16 gallons. See Table A.
Example 3
This example was provided to show the feasibility of
recycle of an aqueous allyl alcohol solution to the contin-
uous process.
Diethylene glycol bis-chloroformate, 82. 9% allyl
alcohol in water, and 50% aqueous caustic soda were
metered to reactor (14) continuously at the rates of 135. 4
gm/min (17. 9 pph), 102. 1 gm/min (13. 5 pph) and 70. 6 gm/
min (9. 3 pph), respectively. 30% aqueous caustic soda
was metered to reactor (16), simultaneously, at the rate of
70. 0 gm/min (9. 3 pph). Temperatures were maintained at
20 0-5C in the reactors. Total molar ratios to each reactor
remained approximately the same as in Example 1 for com-
parison. Caustic concentration to reactor (14) was adjusted
to 50% to compensate for water entering with alcohol.


11~1829




-- 19 --

Organic product (stream 40) from separator ~lowed at 162. 5
gm/min (21. 5 pph) and contained 130, 9 gm/min (17. 3 pph)
ADC monomer representing an 80. 6% yield based on the
bis-chloroformate. Product was stripped to acceptable
5 chloride and ADC monomer levels.


'g

-- 20 --




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~ S Q co o o

q:~ Co CO

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V ~D ~o ~ ~o

¢ ~ 2i~ ~ ~

E~ ~ U7 u~
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a)
O ~ ~ o S
o tJ~
o o o

I
O

~ ~ Q
P: * * Q,


--l *


x x *
~ ~L3 ~ * *

Representative Drawing

Sorry, the representative drawing for patent document number 1121829 was not found.

Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 1982-04-13
(22) Filed 1979-06-29
(45) Issued 1982-04-13
Expired 1999-04-13

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1979-06-29
Registration of a document - section 124 $0.00 1999-05-05
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
ATOCHEM NORTH AMERICA, INC.
Past Owners on Record
PENNWALT CORPORATION
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Description 1994-02-03 20 535
Drawings 1994-02-03 1 18
Claims 1994-02-03 3 73
Abstract 1994-02-03 1 18
Cover Page 1994-02-03 1 10