U.S. patent application number 10/027139 was filed with the patent office on 2002-09-19 for process for the production of polycarbonate.
Invention is credited to Brack, Hans Peter, Cella, James Anthony, Karlik, Dennis, Prada, Lina.
Application Number | 20020132957 10/027139 |
Document ID | / |
Family ID | 26702115 |
Filed Date | 2002-09-19 |
United States Patent
Application |
20020132957 |
Kind Code |
A1 |
Brack, Hans Peter ; et
al. |
September 19, 2002 |
Process for the production of polycarbonate
Abstract
A process for the production of polycarbonate having increased
end-cap levels, the process comprising adding a terminal blocking
agent of the formula: 1 wherein R.sub.1 is a propoxy or butoxy and
R.sub.2 is selected from the group consisting of C.sub.1-C.sub.30
alkyl, C.sub.1-C.sub.30 alkoxy, C.sub.6-C.sub.30 aryl,
C.sub.7-C.sub.30 aralkyl, and C.sub.6-C.sub.30 aryloxy.
Inventors: |
Brack, Hans Peter; (Bergen
op Zoom, NL) ; Cella, James Anthony; (Clifton Park,
NY) ; Karlik, Dennis; (Bergen op Zoom, NL) ;
Prada, Lina; (Murcia, ES) |
Correspondence
Address: |
Frank A. Smith
GE Plastics
One Plastics Avenue
Pittsfield
MA
01201
US
|
Family ID: |
26702115 |
Appl. No.: |
10/027139 |
Filed: |
December 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60258710 |
Dec 28, 2000 |
|
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|
Current U.S.
Class: |
528/196 |
Current CPC
Class: |
C08G 64/14 20130101;
C08G 64/307 20130101 |
Class at
Publication: |
528/196 |
International
Class: |
C08G 064/00 |
Claims
What is claimed is:
1. A process for the production of an aromatic polycarbonate, the
process comprising adding to a polycarbonate oligomer reaction
mixture under melt conditions an amount of a terminal blocking
agent of the following formula: 8to form a polycarbonate having an
increased level of capped or blocked hydroxy groups, wherein at
least 80% of the blocking agent is added after the oligomer has
reached a number-average molecular weight Mn of about 2,500 to
15,000 Dalton, and wherein R.sub.1 is a propoxy or butoxy and
R.sub.2 is selected from the group consisting of C.sub.1-C.sub.30
alkyl, C.sub.1-C.sub.30 alkoxy, C.sub.6-C.sub.30 aryl,
C.sub.7-C.sub.30 aralkyl, and C.sub.6-C.sub.30 aryloxy.
2. The process of claim 1, wherein R.sub.2 is substituted with a
member selected from the group consisting of propoxycarbonyl,
butoxycarbonyl, 2-(propoxycarbonyl)phenyloxycarbonyl,
2-(butoxycarbonyl)phenyloxycarbonyl- ,
2-(propoxycarbonyl)phenyloxycarbonyloxy, and
2-(butoxycarbonyl)phenyloxy- carbonyloxy groups or mixtures
thereof.
3. The process of claim 1, wherein R1 is n-propoxy or butoxy.
4. The process of claim 1, wherein R2 is selected from the group
consisting of stearyl, phenyl, para-t-butyl-phenyl, phenoxy,
para-tert-butylphenoxy, para-octylphenoxy, para-nonylphenoxy,
para-dodecylphenoxy, 3-pentadecylphenoxy, para-octadecylphenoxy,
para-cumylphenoxy, or mixtures thereof.
5. The process according to claim 1, wherein the terminal blocking
agent is added in an amount of about 0.1 to 1.5 mole based on 1
mole equivalent of the free terminal --OH groups of the
polycarbonate at the time of the addition.
6. The process according to claim 5, wherein the terminal blocking
agent is added in an amount of about 0.8 to 1.3 mole equivalent per
mole of the free terminal --OH groups of the polycarbonate at the
time of the addition.
7. The process according to claim 1, further comprising adding to
the polycarbonate under melt conditions a coupling agent select
from the group consisting of: bis-alkylsalicyl carbonate,
bis(2-benzoylphenyl) carbonate, BPA-bis-2-alkoxyphenylcarbonate,
BPA-bis-2-aryloxyphenylcarbon- ate,
BPA-bis-2-benzoylphenylcarbonate and mixtures thereof.
8. The process according to claim 1, wherein the formed
polycarbonate has a content of ortho-substituted phenols generated
in the terminal blocking reaction of 500 ppm or below.
9. The process according to claim 1, wherein the formed
polycarbonate has a content of ortho-substituted phenols generated
in the terminal blocking reaction of 100 ppm or below.
10. The process according to claim 1, wherein the formed
polycarbonate has a content of terminal blocking agent of 500 ppm
or below.
11. The process according to claim 1, wherein the formed
polycarbonate has a content of terminal blocking agent of 100 ppm
or below.
12. The process according to claim 1, wherein the formed
polycarbonate has a content of terminal 2-(alkoxycarbonyl)phenyl
groups of 2,500 ppm or below.
13. The process according to claim 1, wherein the formed
polycarbonate has a content of terminal 2-(propoxycarbonyl)phenyl
groups of 1,000 ppm or below.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Serial No. 60/258,710 filed on Dec. 28, 2000, which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for the
production of polycarbonate and the use of carbonate and ester
derivatives of propels and butyl salicylates as terminal blocking
agents for polycarbonate.
BACKGROUND OF THE INVENTION
[0003] Polycarbonate is a thermoplastic that has excellent
mechanical properties (e.g., impact resistance), heat resistance
and transparency. Polycarbonate is widely used in many engineering
applications. It is known that a high level of end-capping, (i.e.,
wherein most of the terminal phenolic hydroxyl groups in the
polycarbonate are reacted with monofunctional endcapping agents to
form relatively inert polymer chain ends) helps to reduce static,
improve heat aging, and reduce water absorption. Consequently,
various coupling agents and end-cappers have been used to enhance
the end-cap levels in the production of polycarbonate.
[0004] Unexamined Japanese Patent Application H6-157739 discloses
the use of certain non-activated carbonates (e.g., diphenyl
carbonate) and esters as end-capping agents.
[0005] Japanese Patent Application JP-A 7-90074 discloses a method
of producing a polycarbonate from a dihydric compound and a
carbonic acid diester by an ester exchange method. In this method,
a highly active diester, acid halide or acid anhydride with at
least two functional groups is added after the ester exchange ratio
exceeds 70% to obtain a polycarbonate having an enhanced degree of
polymerization. It should be noted that JP-A 7-90074 teaches the
use of de-activated molecules as coupling agents or polymerization
promoters, and not end-cappers.
[0006] U.S. Pat. No. 5,696,222 and European Application No. EP 0
985 696 A1 disclose a method of producing a polycarbonate having a
high-end cap levels by adding certain activated and bis-activated
carbonates as end-cappers. It is disclosed that the end-capping
agents are added to the process after the polycarbonate formed has
an intrinsic viscosity of at least 0.3 dl/g. The resulting
polycarbonate has increased end-cap levels with minimal changes in
molecular weight or intrinsic viscosity (i.e., it has an intrinsic
viscosity that is greater or smaller than the viscosity of the
polycarbonate formed before the addition of the end-cappers by at
most 0.1 dl/g). It is also disclosed that these end-cappers are
activated by a phenolic group having an ortho chlorine atom,
methoxycarbonyl or ethoxycarbonyl group. These end-cappers are high
melting point solids, and thus require complicated and energy
intensive apparatus comprising melting vessels and heated feeding
lines for accurate and controlled feeding of the end-capper to the
polycarbonate.
[0007] EP 0 980 861A1 discloses the use of certain salicylic acid
ester derivatives as terminal blocking agents in amounts of 0.1 to
10 times, and most preferably 0.5 to 2 times, mole per mole
equivalent of terminal hydroxyl groups of the polycarbonate formed
at a time of the addition. Such polycarbonates have good color tone
suitable for optical material use. It is disclosed that these
end-cappers are activated by a phenolic group having an ortho
methoxycarbonyl or ethoxycarbonyl group. It should be noted that
the Examples of EP 0 980 861A1 teach the use of
2-methoxycarbonylphenyl-phenylcarbonate as an end-capper in an
amount that is about 1 mole per mole equivalent of terminal
hydroxyl groups to form a polycarbonate with increased end-cap
levels.
[0008] There is still a need for an improved melt process using
easy to handle low melting end-cappers to produce polycarbonate
having capped terminals and controlled molecular weight.
SUMMARY OF THE INVENTION
[0009] The invention relates to a process for the production of
polycarbonate, the process comprising adding a terminal blocking
agent of the formula: 2
[0010] wherein R.sub.1 is a propoxy or butoxy and R.sub.2 is
selected from the group consisting of C.sub.1-C.sub.30 alkyl,
C.sub.1-C.sub.30 alkoxy, C.sub.6-C.sub.30 aryl, C.sub.7-C.sub.30
aralkyl, and C.sub.6-C.sub.30 aryloxy.
[0011] In one embodiment, R.sub.2 is substituted with a member
selected from the group consisting of a propoxycarbonyl,
butoxycarbonyl, 2-(propoxycarbonyl)phenyloxycarbonyl,
2-(butoxycarbonyl)phenyloxycarbonyl- ,
2-(propoxycarbonyl)phenyloxycarbonyloxy, and
2-(butoxycarbonyl)phenyloxy- carbonyloxy group.
[0012] In another embodiment, R1 is n-propoxy and R2 is selected
from the group consisting of stearyl, phenyl, para-t-butyl-phenyl,
phenoxy, para-tert-butylphenoxy, para-octylphenoxy,
para-nonylphenoxy, para-dodecylphenoxy, 3-pentadecylphenoxy,
para-octadecylphenoxy, para-cumylphenoxy, or mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Applicants have surprisingly found in the process of the
present invention that, by adding a relatively small amount of the
low melting end-cappers or terminal blocking agents of the
invention, the end-capper rapidly caps or blocks the terminal OH
groups of the melt polycarbonate.
[0014] End-capping agent/MW Builder: In the process of the present
invention, the compound of the following formula is added to a
polycarbonate oligomer as an end-capper or terminal blocking agent
and to control the molecular weight of the polycarbonate oligomer:
3
[0015] wherein R.sub.1 is a propoxy or butoxy and R.sub.2 is
selected from the group consisting of C.sub.1-C.sub.30 alkyl,
C.sub.1-C.sub.30 alkoxy, C.sub.6-C.sub.30 aryl, C.sub.7-C.sub.30
aralkyl, and C.sub.6-C.sub.30 aryloxy.
[0016] In one embodiment, R.sub.2 is substituted with a member
selected from the group consisting of a propoxycarbonyl,
butoxycarbonyl, 2-(propoxycarbonyl)phenyloxycarbonyl,
2-(butoxycarbonyl)phenyloxycarbonyl- ,
2-(propoxycarbonyl)phenyloxycarbonyloxy, and
2-(butoxycarbonyl)phenyloxy- carbonyloxy group.
[0017] In a second embodiment, R.sub.1 is n-propoxy or butoxy. In
yet a third embodiment, R.sub.1 is no-propoxy and R.sub.2 is
selected from the group consisting of stearyl, phenyl,
para-t-butyl-phenyl, phenoxy, para-tert-butylphenoxy,
para-octylphenoxy, para-nonylphenoxy, para-dodecylphenoxy,
3-pentadecylphenoxy, para-octadecylphenoxy, para-cumylphenoxy, or
mixtures thereof.
[0018] In another embodiment, endcappers based on derivatives of
n-propyl salicylate or butyl salicylate that have low melting
points such as n-propylsalicyl phenyl carbonate or butylsalicyl
phenyl carbonate are used.
[0019] It is preferred that at least 80%, and more preferably at
least 90% of the total endcapping agent added to the reaction
mixture be added when the number average molecular weight of the
oligomer is between 2,500 and 15,000 Dalton.
[0020] Preparation of the end-capper In one embodiment of the
invention, the end-capper is prepared by the reaction of
appropriate chloroformates (e.g., phenyl chloroformate or
p-cumylphenyl chloroformate) with one equivalent of an activated
phenol, such as propyl salicylate, in a solvent such as methylene
chloride and in the presence of a base to neutralize the liberated
HCl. Additional catalysts may be employed in this reaction to
facilitate the condensation reaction. After completion of the
condensation reaction, the product solution is washed with aqueous
acid and base then with water until the washings are neutral. The
organic solvent may be removed by distillation and the end-capper
is crystallized or distilled and recovered.
[0021] The condensation reaction to prepare the end-capper of the
present invention may be carried out under anhydrous conditions
known in the art using one or more equivalents of a tertiary amine
per equivalent of chloroformate as the base, or under interfacial
conditions also well-known in the art using aqueous sodium
hydroxide as the base in the presence of a condensation catalyst.
In one embodiment, the condensation catalyst is triethyl amine,
quaternary alkyl ammonium salt, or mixtures thereof.
[0022] Terminal Blocking Reaction in the Polycarbonate Production
Process: The terminal blocking agent of the present invention is
used to rapidly cap or block the terminal hydroxy group (OH) of the
polycarbonate to block the terminal of the polycarbonate as shown
below: 4
[0023] The ortho-substituted phenols generated in the reaction of
the formula shown below are less reactive than phenol in backbiting
reactions, which lead to molecular weight degradation of the
polycarbonate. Therefore, the by-product phenols are removed from
the terminal-blocked polycarbonate by distillation to the over-head
system using conventional means (i.e., freeze traps using chilled
water as a coolant) where they can be condensed to expedite the
terminal blocking at high yields.
[0024] It should be noted that the terminal-blocked polycarbonate
may still contain small amounts of any unrecovered phenols, any
unreacted terminal blocking agent along with by-products of any
side reactions to the terminal blocking reactions, e.g. terminal
2-(alkoxycarbonyl)phenyl groups and the like. In one embodiment,
the terminal-blocked polycarbonate contains about less than 500 ppm
of ortho-substituted phenols and about 500 ppm of unreacted
terminal blocking agent of the present invention. In another
embodiment, the terminal-blocked polycarbonate contains about 2,500
ppm or less of terminal 2-(alkoxycarbonyl)phenyl groups.
[0025] In one embodiment, the ortho-substituted phenol by-product
of the following formula is recovered from the overhead system and
reused to prepare new end-cappers or terminating agents. 5
[0026] Melt Polycarbonate Process The process of the present
invention is a melt or transesterification process. The production
of polycarbonates by transesterification is well-known in the art
and described, for example, in Organic Polymer Chemistry by K. J.
Saunders, 1973, Chapman and Hall Ltd., as well as in a number of
U.S. patents, including U.S. Pat. Nos. 3,442,854; 5,026,817;
5,097,002; 5,142,018; 5,151,491; and 5,340,905.
[0027] In the melt process, polycarbonate is produced by the melt
polycondensation of aromatic dihydroxy compounds (A) and carbonic
acid diesters (B). The reaction can be carried out by either a
batch mode or a continuous mode. The apparatus in which the
reaction is carried out can be any suitable type of tank, tube, or
column. The continuous processes usually involve the use of one or
more CSTR's and one or more finishing reactors.
[0028] Examples of the aromatic dihydroxy compounds (A) include
bis(hydroxyaryl) alkanes such as bis(4-hydroxyphenyl)methane; 1,1
-bis(4-tiydroxyphenyl)ethane; 2,2-bis(4-hydroxyphenyl)propane (also
known as bisphenol A); 2,2-bis(4-hydroxyphenyl)butane;
2,2-bis(4-hydroxyphenyl)- octane;
bis(4-hydroxyphenyl)phenylmethane; 2,2-bis(4-hydroxy-
1-methylphenyl)propane; 1,1-bis(4-hydroxy-t-butylphenyl) propane;
and 2,2-bis(4-hydroxy-3-bromophenyl)propane;
bis(hydroxyaryl)cycloalkanes such as
1,1-(4-hydroxyphenyl)cyclopentane and 1,1-bis(4-hydroxyphenyl)cyc-
lohexane; dihydroxyaryl ethers such as 4,4'-dihydroxydiphenyl ether
and 4,4'dihydroxy-3,3'-dimethylphenyl ether; dihydroxydiaryl
sulfides such as 4,4'-dihydroxydiphenyl sulfide and
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; dihydroxydiaryl
sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; and dihydroxydiaryl
sulfones such as 4,4'-dihydroxydiphenyl sulfone and
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone. In one embodiment,
the aromatic dihydroxy compound is bisphenol A (BPA).
[0029] Examples of the carbonic acid diesters (B) include diphenyl
carbonate; ditolyl carbonate; bis(chlorophenyl)carbonate; m-cresyl
carbonate; dinaphthyl carbonate; bis(diphenyl) carbonate; diethyl
carbonate; dimethyl carbonate; dibutyl carbonate; and dicyclohexyl
carbonate. In one embodiment of an industrial process, diphenyl
carbonate (DPC) is used.
[0030] In one embodiment of the invention, the terminal blocking
agent of the present invention is added together with DPC or
another diaryl carbonate.
[0031] The carbonic diester component may also contain a minor
amount, e.g., up to about 50 mole % of a dicarboxylic acid or its
ester, such as terephthalic acid or diphenyl isophthalate, to
prepare polyesterpolycarbonates.
[0032] In preparing the polycarbonates, usually about 1.0 mole to
about 1.30 moles of carbonic diester are utilized for every 1 mole
of the aromatic dihydroxy compound. In one embodiment, about 1.01
moles to about 1.20 moles of the carbonic diester is utilized.
[0033] Optional Terminators/End-capping Agents. In one embodiment
of the melt process, additional/optional terminators or end-capping
agents of the prior art may also be used. Examples of terminators
include phenol, p-tert-butylphenol, p-cumylphenol, octylphenol,
nonylphenol and other endcapping agents well-known in the art.
[0034] Optional Branching Agents. In one embodiment of the process
of the present invention, branching agents are used as needed.
Branching agents are well-known and may comprise polyfunctional
organic compounds containing at least three functional groups,
which may be hydroxyl, carboxyl, carboxylic anhydride, and mixtures
thereof. Specific examples include trimellitic acid, trimellitic
anhydride, trimellitic trichloride, tris-p-hydroxy phenyl ethane,
isatin-bis-phenol, tris-phenol TC
(1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene), tris-phenol PA
(4(4(1,1-bis(p-hydroxyphenyl)-ethyl) alpha,alpha-dimethyl
benzyl)phenol, trimesic acid and benzophenone tetracarboxylic
acid.
[0035] Optional Coupling Agent. In one embodiment of the process of
the present invention, a coupling agent such as a bis-alkylsalicyl
carbonate, e.g., bis-methyl or ethyl or propyl salicyl carbonate,
bis-phenyl or benzyl salicyl carbonate, bis(2-benzoylphenyl)
carbonate, BPA-bis-2-alkoxyphenylcarbonate,
BPA-bis-2-aryloxyphenylcarbonate, or
BPA-bis-2-benzoylphenylcarbonate is used in conjunction with the
end-capper in order to obtain a faster and/or greater build in
molecular weight in the polycarbonate oligomer.
[0036] Optional catalysts. The polycarbonate synthesis may be
conducted in the presence of a catalyst to promote the
transesterification reaction. Examples include alkali metals and
alkaline earth metals by themselves or as oxides, hydroxides, amide
compounds, alcoholates, and phenolates, basic metal oxides such as
ZnO, PbO, and Sb.sub.2O.sub.3, organotitanium compounds, soluble
manganese compounds, nitrogen-containing basic compounds and
acetates of calcium, magnesium, zinc, lead, tin, manganese,
cadmium, and cobalt, and compound catalyst systems such as a
nitrogen-containing basic compound and a boron compound, a
nitrogen-containing basic compound and an alkali (alkaline earth)
metal compound, and a nitrogen-containing basic compound, an alkali
(alkaline earth) metal compound, and a boron compound.
[0037] In one embodiment of the invention, the transesterification
catalyst is a quaternary ammonium compound or a quaternary
phosphonium compound. Non-limiting examples of these compounds
include tetramethyl ammonium hydroxide, tetramethyl ammonium
acetate, tetramethyl ammonium fluoride, tetramethyl ammonium
tetraphenyl borate, tetraphenyl phosphonium fluoride, tetraphenyl
phosphonium tetraphenyl borate, tetrabutyl phosphonium hydroxide,
and dimethyl diphenyl ammonium hydroxide.
[0038] The above-mentioned catalysts may each be used by themself,
or, depending on the intended use, two or more types may be used in
combination. When more than one catalyst is employed, each may be
incorporated into the melt at a different stage of the
reaction.
[0039] The appropriate level of catalyst will depend in part on how
many catalysts are being employed, e.g., one or two. In general,
the total amount of catalyst is usually in the range of about
1.times.10.sup.-8 to about 1.0 mole per mole of the dihydroxy
compound. In one embodiment, the level is in the range of about
1.times.10.sup.-5 to about 5.times.10.sup.-2 mole per mole of
dihydroxy compound. When more than one catalyst is employed, each
may be incorporated into the melt at a different stage of the
reaction.
[0040] Other optional components in the polycarbonate In the
present invention, the polycarbonate obtained may further contain
at least one of a heat stabilizer, an ultraviolet absorbent, a mold
releasing agent, a colorant, an anti-static agent, a lubricant, an
anti-fogging agent, a natural oil, a synthetic oil, a wax, an
organic filler and an inorganic filler, which are generally used in
the art.
[0041] Adding the terminal blocking agent to the melt process The
method of adding the end-capper of the present invention to
polycarbonate is not specially limited. For example, the end-capper
may be added to the polycarbonate as a reaction product in a batch
reactor or a continuous reactor system. In one embodiment, the
end-capper is added to the melt polycarbonate just before or after
a later reactor, i.e., a polymerizer, in a continuous reactor
system. In a second embodiment, the end-capper is by reactive
extrusion after the last polymerizer in the continuous reactor
system. In a third embodiment, it is added between the 1.sup.st and
2.sup.nd polymerizer in a continuous reactor system. In yet another
embodiment, the end-capper is added between the 2.sup.nd reactor
and the 1.sup.st polymerizer.
[0042] The end-capper or terminal blocking agent is added at a
stoichiometry of about between 0.3 and 2.0 relative to the free OH
content of the polycarbonate oligomer to which it is added. In one
embodiment, it is added at a stoichiometry of about 0.5 to 1.5. In
another embodiment, it is added at a stoichiometry of about of 0.8
to 1.3 relative to the free OH that would be obtained in the final
targeted molecular weight of the polycarbonate and no other
end-capper is used.
[0043] The apparatus/method for feeding the end-capper is not
specially limited. The end-capper may be added in the form of a
solid, a liquid, a melt or a solution thereof. Further, the
end-capper may be added in a predetermined amount once, or it may
be separated into predetermined amounts and added several times. In
one embodiment, it is added to the process as a powder by means of
a static mixer.
[0044] In embodiments wherein low melting point end-cappers are
used, it is not necessary to require melting drums and heated
addition lines for the end-capper addition system since the risk of
blockages in the addition system or lines due to solidification of
the end-capper in cold spots is minimal.
EXAMPLES
[0045] The present invention will be explained hereinafter with
reference to Examples, while the present invention shall not be
limited by Examples.
[0046] End-cappers. The end-cappers used in the examples were
prepared as follows:
[0047] Propyl salicyl phenyl carbonate To a solution of 29.7 g
(0.165 mol) propyl salicylate and triethylamine, 16.66 g (0.165
mol) in 200 ml of toluene was added dropwise over 30 minutes, a
solution of phenyl chloroformate, 25.24 g (0.164 mol) in 50 ml of
toluene. When addition was complete, the reaction mixture was
stirred for one hour at room temperature and filtered. The filtrate
was washed succesively with 200 ml of 2% aqueous NaOH, 2.times.200
ml of 10% HCl and 200 ml of saturated sodium chloride. After
passage through a cone of anhydrous CaSO.sub.4, the solvent was
removed on a rotary evaporator to afford a an oil which was
distilled to afford 39 g (79.3%) of a colorless oil (boiling point
or "bp" of 155-165.degree. C. @ 3.5 mm Hg). .sup.1H NMR
(CDCl.sub.3) .delta. 8.2-7.3 (m,9,ArH), 4.40
(t,2,OCH.sub.2CH.sub.2CH.sub.3), 2.00
(m,2,OCH.sub.2CH.sub.2CH.sub.3) and 1.15 ppm
(t,3,OCH.sub.2CH.sub.2CH.sub- .3).
[0048] i-Propyl salicyl phenyl carbonate In a manner similar to
that described in the above procedure, phenyl chloroformate, 21.6 g
(0.138 mol) in toluene was added dropwise to a solution of i-propyl
salicylate, 25.0 g (0.139 mol) and 14.0 g (0.139 mol) of
triethylamine in 200 ml of toluene. The usual work-up afforded an
oil which was distilled to afford 34.4 g (83.1%) of a colorless oil
(bp=155-165.degree. C. @ 0.3 mm Hg). .sup.1H NMR (CDCl.sub.3)
.delta. 8.2-7.3 (m,9, ArH) 5.4 (m,1,OCH(CH.sub.3).sub.2) and 1.4
ppm (d,6,OCH(CH.sub.3).sub.2).
[0049] Butyl salicyl phenyl carbonate In a manner similar to that
described in the above procedures, phenyl chloroformate, 20.66 g
(0.132 mol) in toluene was added dropwise to a solution of butyl
salicylate, 25.88 g (0.133 mol) and 13.4 g (0.133 mol) of
triethylamine in 200 ml of toluene. The usual work-up afforded an
oil which was distilled to afford 32.5 g (78.5%) of a colorless oil
(bp=190-200.degree. C. @ 0.2 mm Hg). .sup.1H NMR (CDCl.sub.3)
.delta. 8.2-7.3 (m,9, ArH) 4.4 (t,
2,OCH-.sub.2(CH.sub.2).sub.2CH.sub.3), 1.75 (m,2,
OCH.sub.2CH.sub.2CH.sub- .2CH.sub.3), 1.50 75 (m,2,
OCH.sub.2CH.sub.2CH.sub.2CH.sub.3)and 0.95 ppm (t,3,
OCH.sub.2CH.sub.2CH.sub.2CH.sub.3).
[0050] Propyl salicyl p-cumylphenyl carbonate A solution of propyl
salicylate, 25.0 g (0.139 mol) and p-cumylphenyl chloroformate,
38.0 g (0.138 mol) in 200 ml of CH.sub.2Cl.sub.2 was treated
dropwise over 10 minutes with a solution of sodium hydroxide, 6.0 g
(0.15 mol) and methyltributylammonium hydroxide (0.5 ml of a 70%
aqueous solution) in 100 ml of water. The two phase mixture was
stirred an additional 10 minutes and the organic layer was
separated and washed with 2.times.200 ml of 10% HCl and 1.times.200
ml of saturated sodium chloride. After passage of the solution
through a cone of anhydrous CaSO.sub.4, solvent and excess propyl
salicylate were removed under vacuum to afford 56.7 g (98.3%) of a
light amber oil consisting of the desired product. .sup.1H NMR
(CDC1.sub.3) .delta. 8.15-7.3 (m,13,ArH), 4.35
(t,2,OCH.sub.2CH.sub.2CH.sub.3), 1.8
(m,2,OCH.sub.2CH.sub.2CH.sub.3), 1.75 (s,6,ArC(CH.sub.3).sub.2) and
1.05 (t,3,OCH.sub.2CH.sub.2CH.sub.3).
[0051] Starting Material Polycarbonate In all examples, either
starting polycarbonate grade A or B was used. The starting
materials were prepared by a melt process in a continuous reactor
system with the following properties:
1 Polycarbonate A Polycarbonate B Weight-average molecular weight
Mw: 18.3 * 10.sup.3 g/mole 28.8 * 10.sup.3 g/mole Number-average
molecular weight Mn: 8.34 * 10.sup.3 g/mole 11.7 * 10.sup.3 g/mole
Free OH content: 670 ppm 967 ppm End-cap ratio 83.6% 66.7%
[0052] In the Examples, the following measurements were made.
[0053] a) Molecular weight: Mw and Mn were measured by GPC analysis
of 1 mg/ml polymer solutions in methylene chloride versus
polystyrene standards. The measured polycarbonate Mw and Mn values
were then corrected for the difference in retention volume between
polycarbonate and polystyrene standards.
[0054] b) Free-OH content was measured by UV/Visible analysis of
the complexes formed from the polymer with TiCl.sub.4 in methylene
chloride solution. In some cases the Free OH content was measured
by a direct UW method.
[0055] c) End-cap levels were calculated from the free OH content
and Mn values.
Examples 1-2
[0056] A batch reactor tube was charged under nitrogen with 25 g of
polycarbonate A and 1.084.times.10.sup.-3 mole of either end-capper
n-Propyl Salicyl Phenyl Carbonate (0.3254 g of "n-PSPC"--Example 1)
or end-capper Butyl Salicyl Phenyl Carbonate (0.3407 g of
"BSPC"--Example 2) of formulae (1) and (2). The mixture was heated
to a temperature of 300.degree. C. and stirred for 20 minutes.
After the melt mixing, stage vacuum was applied to the system to a
pressure of 0.5 mbar and the reaction continued for 20 minutes.
After the reaction stage, the polymer was sampled from the reaction
tube. The results are shown in table 1. 6
Comparative Examples 1-5
[0057] Example 1 was repeated but either no end-capper was used, or
various other end-cappers of the following formulae were used
instead. The results are also shown in table 1. 7
Example 3
[0058] The same conditions as in examples 1-2 except that
Polycarbonate B was used instead of A and that 0.4696 g (1.564 *
10.sup.-3 mole) of n-Propyl Salicyl Phenyl Carbonate (n-PSPC) was
used as an end-capper instead. The results are also shown in table
1.
Comparative Examples 6-7
[0059] Example 3 was repeated except that no end-capper was used
for comparative example 6, and 0.3350 g (1.564 * 10.sup.-3 mole) of
Diphenyl Carbonate was used as an end-capper for comparative
example 7. The results are in table 1.
2TABLE 1 Starting Amount Reaction Mw Mn End-cap Example Material
End-capper/Blocking Agent Used mole/--OH time min. g/mole g/mole %
Starting A -- -- -- 18.3 E+03 8.34 E+03 83.6 Material Starting B --
-- -- 28.8 E+03 11.7 E+03 66.7 Material 1 A n-Propyl Salicyl Phenyl
Carbonate 1.1 20 19841 8901 91.3 2 A Butyl Salicyl Phenyl Carbonate
1.1 20 18167 8074 90.7 Comp. 1 A -- -- 20 20992 11740 85.1 Comp. 2
A Diphenyl Carbonate 1.1 20 21058 11692 88.1 Comp. 3 A Methyl
Salicyl Phenyl Carbonate 1.1 20 19631 10623 90.2 Comp. 4 A Ethyl
Salicyl Phenyl Carbonate 1.1 20 18877 8298 89.7 Comp. 5 A
Iso-Propyl Salicyl Phenyl Carbonate 1.1 20 19480 8669 87.0 3 B
n-Propyl Salicyl Phenyl Carbonate 1.1 20 28605 11840 75.9 Comp. 6 B
-- -- 20 30470 12272 61.6 Comp. 7 B Diphenyl Carbonate 1.1 20 25634
11102 64.8
* * * * *