Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2002-03-22
2004-08-03
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C264S219000, C502S009000, C528S198000
Reexamination Certificate
active
06770731
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a novel branched melt-polymerized polycarbonate having pronounced non-Newtonian flow behavior, to compositions containing it and to molded articles produced therefrom. The invention relates also to a process for the preparation of such a polycarbonate.
SUMMARY OF THE INVENTION
A branched melt-polymerized polycarbonate having pronounced non-Newtonian flow behavior is disclosed. The polycarbonate is suitable for preparing molding compositions and the preparation of a variety of molded articles.
BACKGROUND OF THE INVENTION
Polycarbonate is produced industrially by means of the interface process or by transesterification in the melt (melt polymerization process). The melt polymerization process is becoming increasingly of interest because it can be carried out without the use of phosgene or chlorinated solvents. Polycarbonates produced by the interface process, which is mainly used nowadays, are linear, such polymers containing no multifunctional structural units. This type of linear polycarbonate, which lacks the multifunctional structural units capable of branching, has only slight non-Newtonian flow behavior. In order to achieve branching during the interface process, a branching agent must be added. Owing to the resulting branching with multifunctional structural units, the flowability of the polymer at a low shear rate is increased and at a high shear rate is reduced.
Polycarbonates produced by the melt polymerization process necessarily contain multifunctional structural units. The unavoidable production of multifunctional branching structural units during the polymerization is known and is described, for example, in Angewandte Chemie 20, p. 633-660, 1956.
U.S. Pat. No. 5,932,683 describes a melt process whereby a melt polycarbonate having three particular structural units is formed. A particular relationship between the reaction time and the reaction temperature is mentioned as a parameter for the preparation of that polycarbonate. The described polycarbonate exhibits particularly ready flow behavior at high shear rates. However, that flow behavior is usually coupled with poor flowability at low shear rates.
The object was, therefore, to develop a melt polycarbonate which, in addition to having good flowability at high shear rates, is not less flowable than unbranched polycarbonate at low shear rates.
DETAILED DESCRIPTION OF THE INVENTION
The object was achieved by a melt process, which does not correspond to the parameters mentioned in U.S. Pat. No. 5,932,683, which produces a melt polycarbonate containing a novel tetrafunctional structural unit. However, that particular branched polycarbonate nevertheless exhibits flow behavior at a low shear rate that is comparable to the flow behavior of unbranched polycarbonate from the interface, while the flow behavior at a high shear rate is improved. The polycarbonate according to the invention may therefore be used particularly successfully in injection molding, and it is, moreover, comparable to an unbranched polycarbonate when it is extruded.
The polycarbonate according to the invention has the general formula (1)
wherein the square brackets enclose repeating structural units of the polycarbonate,
M denotes Ar or a multifunctional compound A,
wherein
Ar conforms to formula (2)
or, particularly preferably, to formula (3)
wherein
Z is C
1
-C
8
-alkylidene or C
5
-C
12
-cycloalkylidene, S, SO
2
or a single bond,
R is a substituted or unsubstituted phenyl, methyl, propyl, ethyl, butyl, Cl or Br, and
n represents 0, 1 or 2,
wherein
Y is H or a group conforming to formula (4)
wherein
R′ denotes H, C
1
-C
20
-alkyl, C
6
H
5
or C(CH
3
)
2
C
6
H
5
and where there are several R groups they may be identical or different one from the others, and
n represents 0, 1 or 2,
wherein the multifunctional compound A is a compound of the formula
wherein
X denotes Y or —(MOCOO)Y,
wherein M+Y has the above-mentioned meaning,
that may be present in the polycarbonate in an amount of from 201 to 5000 ppm, preferably from 350 to 2000 ppm and most preferably from 300 to 1000 ppm. Compound A is particularly preferably a compound of the formula
The polycarbonate according to the invention may additionally contain compounds B, C and D.
Compound B is a multifunctional compound of the formula
and may be present in the polycarbonate in an amount of from 1501 to 10,000 ppm, preferably from 1550 to 3000 ppm, most preferably from 1600 to 2000 ppm. Compound B is particularly preferably a compound of the formula
Compound C is a multifunctional compound of the formula
and may be present in the polycarbonate in an amount of from 351 to 5000 ppm, preferably from 400 to 2000 ppm and most preferably from 450 to 1000 ppm.
Compound C is particularly preferably a compound of the formula
In compounds A1, B, B1, C and C1, X is as defined for compound A.
Compound D is a compound of the formula
and may be present in the polycarbonate in an amount of from 751 to 5000 ppm, preferably from 800 to 2000 ppm, most preferably from 850 to 1500 ppm.
Compound D is particularly preferably a compound of the formula
The polycarbonate according to the invention may have a weight-average molecular weight, determined by gel permeation chromatography, of from 5000 to 80,000, preferably from 10,000 to 60,000 and most preferably from 15,000 to 40,000.
The polycarbonate according to the invention may also be defined by the shear thinning ratio y in accordance with the equation
y>
0.30+0.1312
x
14.881
,
wherein x is the relative viscosity of the polycarbonate. The shear thinning ratio serves to quantify the flow behavior. The shear thinning ratio is the ratio of the viscosity at a low shear rate to the viscosity at a high shear rate. According to the invention, the shear thinning ratio is the ratio of the viscosity at a shear rate of 50 s
−1
to the viscosity at a shear rate of 5000 s
−1
measured at 280° C.
Despite the high number of branchings and the pronounced non-Newtonian flow behavior associated therewith, the polycarbonate according to the invention has excellent color and color stability during injection molding. It exhibits markedly less yellowing than do the known melt polycarbonates.
The preparation of aromatic polycarbonates by the melt transesterification process is known and is described, for example, in “Schnell”, Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. 9, Interscience Publishers, New York, London, Sydney 1964, reference is made to D. C. PREVORSEK, B. T. DEBONA and Y. KESTEN, Corporate Research Center, Allied Chemical Corporation, Moristown, N.J. 07960, “Synthesis of Poly(ester)carbonate Copolymers” in Journal of Polymer Science, Polymer Chemistry Edition, Vol. 19, 75-90 (1980), to D. Freitag, U. Grigo, P. R. Müller, N. Nouvertne, BAYER AG, “Polycarbonates” in Encyclopedia of Polymer Science and Engineering, Vol. 11, Second Edition, 1988, pages 648-718, and finally to Des. U. Grigo, K. Kircher and P. R. Müller “Polycarbonate” in Becker/Braun, Kunststoff-Handbuch, Volume 3/1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag Munich, Vienna 1992, pages 117-299, all incorporated by reference herein.
The polycarbonate according to the invention, which may also be a polyester carbonate, is prepared by the melt transesterification reaction of suitable diphenols and carbonic acid diaryl esters in the presence of a suitable catalyst. The polycarbonate may also be prepared by the condensation of carbonate oligomers, which contain hydroxy or carbonate terminal groups, and suitable diphenols as well as carbonic acid diaryl esters.
Suitable carbonic acid diaryl esters in connection with the invention are di-C
6
- to C
14
-aryl esters, preferably the diesters of phenol or of alkyl-substituted phenols, i.e. diphenyl carbonate, dicresyl carbonate and di-4-tert-butylphenyl carbonate. Diphenyl carbonate is most preferred.
Suitable carbonate oligomers are described by the above formula (1) with molecular weights of from 220 to 15,000.
The suitable di-C
6
-C
14
-
Hucks Uwe
Kratschmer Silke
Mason James
Boykin Terressa
Gil Joseph C.
Matz Gary F.
Preis Aron
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