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
2004-03-02
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C502S009000, C528S198000
Reexamination Certificate
active
06699959
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to polycarbonate resins and more particularly to a process for the preparation of polycarbonate.
SUMMARY OF THE INVENTION
A melt-polymerized polycarbonate is disclosed. The polycarbonate has a shear thinning ratio (y) that is defined by the limiting values of the following equation
c+ax
b
>y>−c+ax
b
(Q)
wherein y≧1, c=0.3 to 0.1, b=14.831±0.05 to 0.02, a=0.1262±0.005 to 0.003 and x is the relative viscosity of the polycarbonate. The polycarbonate exhibits a flow behavior similar to that of a linear polycarbonate of comparable molecular weight obtained by the interface polymerization process.
BACKGROUND OF THE INVENTION
Polycarbonate is produced industrially by means of the interface process or by trans-esterification in the melt (melt polymerization process). The melt polymerization process is becoming increasingly important since it can be carried out without the use of phosgene or chlorinated solvents. Polycarbonates produced by the interface polymerization process that is mainly used at the present time are linear, and such polymers do not contain any multifunctional structural units. This type of linear polycarbonate, which lacks the multifunctional structural units capable of undergoing branching, has only a slight non-Newtonian flow behavior.
Polycarbonates produced using the melt polymerization process contain multi-functional structural units, are highly branched, and have an excellent non-Newtonian flow behavior. The unavoidable production of multifunctional branching structural units during the polymerization is known and is described for example in Angewandte Chemie 20, pp. 633-660, 1956. On account of their different flow properties it is difficult to use these two types of polycarbonates interchangeably in for example injection molding processes or extrusion processes.
Typical melt-polymerized polycarbonate contains branching units that lead to an excellent, non-Newtonian flow behavior that is usually characterized by the shear thinning ratio. The branching unfortunately also leads to an unacceptable yellow discoloration.
DE 42 38 123 A describes a process for the production of melt-polymerized polycarbonate having a low proportion of branching units, though no details of the flow behavior of the resultant polycarbonate are given.
U.S. Pat. No. 5,932,683 discloses a typical melt polymerization process in which a typical branched polycarbonate is produced having a pronounced non-Newtonian flow behavior. In addition special branching structural units that are necessary for the pronounced non-Newtonian flow behavior are disclosed, as well as a special relationship between the reaction time and reaction temperature, a sufficient number of branching being produced within these defined parameters so as to achieve the pronounced non-Newtonian flow behavior while retaining the other good properties of the polycarbonate.
The object of the present invention is to provide a melt-polymerized polycarbonate having rheological properties that are comparable to those of an interface-polymerized polycarbonate, wherein these polycarbonates exhibit excellent color and color stability.
DETAILED DESCRIPTION OF THE INVENTION
This object is achieved by a melt-polymerized polycarbonate with a shear thinning ratio (y) that is defined by the limiting values of the following equation
c+ax
b
>y>−c+ax
b
(Q)
for all y≧1,
wherein a, b and c are constants, and
c=0.3 to 0.1, preferably 0.2 to 0.1, and most preferably about 0.1,
b=14.83±0.05 to 0.02, preferably ±0.04 to 0.02, and most preferably ±about 0.02, and
a=0.1262±0.005 to 0.003, preferably ±0.004 to 0.003, and most preferably ±about 0.003, and
x is the relative viscosity of the polycarbonate.
The shear thinning ratio serves to quantify the flow behavior. The shear thinning ratio is defined as 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 50s
−1
to the viscosity at a shear rate of 5,000 s
−1
measured at 280° C.
It was surprisingly found that the polycarbonate produced according to the invention by melt polymerization (transesterification process) contains multifunctional structural units capable of branching but nevertheless exhibits a slight non-Newtonian flow behavior that is equivalent to that of linear polycarbonates produced by interface polymerization. This is surprising since all previously known melt-polymerized polycarbonates exhibit a very much more pronounced non-Newtonian flow behavior than linear polycarbonates. The polycarbonates according to the invention exhibit an excellent color stability during injection molding.
The melt-polymerized polycarbonates according to the invention correspond to the general formula (1)
wherein the square brackets denote repeating structural units,
M denotes Ar or a multifunctional compound A, B, C as well as compound D,
wherein Ar is represented by Formula (2)
or particularly preferably a compound that is represented by Formula (3)
wherein
Z denotes C
1
-C
8
alkylidene or C
5
-C
12
cycloalkylidene, S, SO
2
or a single bond, R denotes a substituted or unsubstituted phenyl, methyl, propyl, ethyl, butyl, Cl or Br, and n denotes 0, 1 or 2,
wherein the multifunctional compound A is a compound of the formula
and may be contained in an amount of less than 1,500 ppm, preferably less than 1,000 ppm, most particularly preferably less than about 500 ppm in the polycarbonate,
wherein the multifunctional compound B is a compound of the formula
and may be contained in an amount of less than 350 ppm, preferably less than 250 ppm, most particularly preferably less than about 100 ppm in the polycarbonate, wherein the multifunctional compound C is a compound of the formula
and may be contained in an amount of less than 200 ppm, preferably less than 150 ppm, most particularly preferably less than about 100 ppm in the polycarbonate, wherein compound D is a compound of the formula
and may be contained in an amount of less than 750 ppm, preferably less than 500 ppm, most particularly preferably less than about 300 ppm in the polycarbonate, wherein
Y is H or a compound of the formula (4)
wherein
R may be identical or different and denotes H, C
1
-C
20
alkyl, -alkylaryl, -cycloalkyl, -oxyalkyl, -oxyaryl, C
6
H
5
or C(CH
3
)
2
C
6
H
5
, and
n may be 0, 1, 2 or 3,
wherein X=Y or —(MOCOO)Y,
wherein M and Y have the meanings given above and these definitions also apply to the compounds mentioned hereinafter.
The polycarbonate according to the invention has a weight average molecular weight as determined by gel permeation chromatography of 5,000 to 80,000, preferably 10,000 to 60,000, and most particularly preferably 15,000 to 40,000.
Ar preferably has the following meaning:
Preferably the multifunctional compound A corresponds to the following formula:
Preferably the multifunctional compound B corresponds to the following formula:
Preferably the multifunctional compound C corresponds to the following formula:
Preferably the multifunctional compound D corresponds to the following formula:
The production of aromatic polycarbonates according to 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, in 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), in D. Freitag, U. Grigo, P. R. Müller, N. Nouvertne, Bayer AG, “Polycarbonates” in Encyclopedia of Polymer Science and Engineering, Vol. 11, Second Edition, 1988, pp. 648-718 and finally in U. Gri
Hucks Uwe
Kratschmer Silke
Mason James
Bayer Aktiengesellschaft
Boykin Terressa
Gil Joseph C.
Matz Gary F.
Preis Aron
LandOfFree
Polycarbonate having a low shear thinning behavior does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polycarbonate having a low shear thinning behavior, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polycarbonate having a low shear thinning behavior will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3193023