Carbonate blend polymer compositions comprising a high molecular weight branched carbonate polymer component and methods for their preparation

Novel carbonate polymer blend compositions and processes for their preparation are disclosed where an amount of a high molecular weight branched carbonate polymer component (HMWB PC) is combined with a second, lower molecular weight polycarbonate. A HMWB PC component is selected which is homogeneously dispersible in a blend with the second component. A preferred aspect of the invention is directed to intermediate compositions and processes for their use where the second PC is combined with a HMWB PC precursor having latent themally reactive moieties which can be activated to produce a desired and controlled level of high molecular weight, branched carbonate polymer component. Arylcyclobutene moleties are found to be preferred latent thermally reactive moleties. The carbonate polymer blends according to the present invention have surprisingly improved combinations of physical properties, thermal stability, color, melt strength, transparency and processability. When shaped or molded into various types of articles, the articles posses these very desirable properties and are additionally able to be provided with a low gloss or matte surface. These polymeric compositions are well suited for use in preparing molded articles, such as injection molded articles; composite or blend materials with further filler or blend components; extruded articles such as sheet, fiber or film; and blow molded or thermoformed articles.

FIELD OF THE INVENTION 
This invention relates to novel carbonate polymer blend compositions 
comprising two carbonate polymer components. As first component, the blend 
comprises an amount of a high molecular weight, branched carbonate polymer 
component ("HMWB PC"). As second component the blend comprises an amount 
of a lower molecular weight carbonate polymer. According to a preferred 
aspect of the invention, the high molecular weight component is 
homogeneously dispersible, preferably soluble or miscible therein. The 
invention also involves an improved intermediate blend composition for 
preparing such compositions which intermediate composition comprises a 
precursor for the first component. This precursor is a carbonate polymer 
having latent themally reactive moieties which can be thermally activated 
to produce a desired and controlled level of high molecular weight, 
branched carbonate polymer component. 
Improved carbonate polymer blend compositions are very easily prepared when 
the precursor for the first carbonate polymer component is combined with 
an amount of a second carbonate polymer and the latently reactive moieties 
are themally activated to produce a high molecular weight, branched 
carbonate polymer component. These polymeric compositions are well suited 
for use in preparing molded articles, such as injection molded articles; 
composite or blend materials with further filler or blend components; 
extruded articles such as sheet, fiber or film; and blow molded or 
thermoformed articles. 
BACKGROUND OF THE INVENTION 
It is known that articles prepared from a carbonate polymer ("PC") having a 
higher molecular weight (Mw) possess generally better physical properties 
than if molded from a lower molecular weight carbonate polymer. Unless 
otherwise indicated, the references to "molecular weight" herein refer to 
weight average molecular weights ("Mw") determined on the carbonate 
polymers using gel permeation chromatography with a bisphenol A 
polycarbonate standard. Otherwise, viscometry or light scattering can also 
be used to determine weight average molecular weight. It should be noted 
that various references, including several that are discussed below, refer 
to "viscosity average" molecular weight, which is not the same as weight 
average molecular weight but can be correlated or converted to Mw values. 
It is also known that the higher the molecular weight of the carbonate 
polymers, the more difficult they are to process due to their higher 
viscosity and corresponding lower melt flow rate. See for example Japanese 
Patent Publication 03-243,655 (1992) where amounts of a lower molecular 
weight carbonate polymer are incorporated into a high molecular carbonate 
polymer composition in attempting to improve the flow and processability 
properties of such carbonate polymers. However, it is known that the 
separately prepared higher and lower molecular weight components are 
difficult to homogeneously blend due to their difference in melt 
viscosities and do not produce the best possible combinations of polymer 
processability and molded part physical properties. 
It is well known that branched carbonate polymers are commercially 
available and are known to have greater melt strength and be more shear 
sensitive in the melt phase than linear polycarbonates. Therefore, the 
branched polycarbonates are known to be better suited for some uses such 
as blow molding or thermoforming. In Japanese Patent Publication 
60-215,051 (1985), it is shown that branched resins can be incorporated in 
varying amounts into blends with a high melt flow rate (low molecular 
weight) linear carbonate polymer to improve the melt strength of the low 
molecular weight resin. It is also known that additives, such as Teflon 
polytetrafluoroethylenes, can be added to polycarbonates to provide an 
increase in melt strength but have drawbacks such as loss in transparency 
and toughness. 
In U.S. Pat. No. 4,912,914 it is proposed that crosslinked or branched 
polycarbonates can be prepared by incorporating a diester diphenolic 
monomer into the carbonate polymer backbone, then heat activating the 
crosslinking reaction. However, since the crosslinking reaction causes the 
polymer backbone to be cut at the point of crosslinking, the polymers that 
are taught would be expected to have undesirable levels of low molecular 
weight polymer byproducts and high molecular weight or crosslinked gel 
byproducts due to the random and uncontrollable crosslinking. These 
polymers would also be expected to have higher color levels and reduced 
hydrolytic stability. 
In U.S. Pat. No. 3,770,697 and U.S. Pat. No. 3,652,715 carbonate polymers 
are provided with thermally activated, terminal or pendant unsaturated 
imido groups. These functionalized, curable polymers are then taught to be 
employed independently or in mixtures with other monomers or polymers, as 
molding compounds, films, laminates, and the like. A cast film that was 
prepared from a blend of an imido-sunctionalized carbonate polymer 
composition and an amount of standard, non-functionalized polycarbonate 
and reacted using an additional chemical initiator compound showed an 
increase in heat resistance. It has been found, however, that the 
molecular weight of these products is unstable and that the products have 
an undesirable discoloration. It has also been found, unfortunately, that 
such unsaturated imido-functionalized carbonate polymers are not readily 
produced in interfacial carbonate polymer production processes due to the 
nitrogen-containing imido groups that must be incorporated. In addition, 
the initiation and reaction process requires relatively long reaction 
times. 
It is therefore a goal of the present invention to provide improved 
carbonate polymer compositions which are easily prepared and possess good 
combinations of processability, stability and physical properties. 
Preferably such compositions are easily prepared from one or more 
components produced in an interfacial carbonate polymer process. It is 
also desired to prepare such compositions without having to incorporate an 
additional free radical initiating compound such as an organic peroxide or 
employ radiation techniques which can also lead to polymer decomposition. 
It is also desired to prepare such improved carbonate polymer blend 
compositions using a high molecular weight branched carbonate polymer 
component that can be readily mixed homogeneously into the second 
component while avoiding unacceptable levels of gel that detract from the 
balance of the desirable physical, theological and optical properties. 
SUMMARY OF THE INVENTION 
Therefore, in one aspect the invention is a carbonate polymer blend 
composition comprising a first high molecular weight branched carbonate 
polymer component and a second, different carbonate polymer component 
having a lower molecular weight than the first component, characterized in 
that the first high molecular weight branched carbonate polymer component 
is themally stable at a temperature at least 100.degree. C. above the Tg 
of the carbonate polymer blend composition. Preferably the first carbonate 
polymer component is prepared from a precursor component comprising a 
carbonate polymer having one or more latently reactive moieties capable of 
forming a high molecular weight branched carbonate polymer upon heat 
activation. 
In another aspect, the present invention is an intermediate carbonate 
polymer blend composition suitable for preparing a carbonate polymer blend 
composition as described above comprising a precursor component having one 
or more latently reactive moleties capable of forming a high molecular 
weight branched carbonate polymer upon heat activation and a second, 
different carbonate polymer component having a lower molecular weight than 
the high molecular weight branched component. In a preferred aspect, the 
precursor component comprises terminally located, latently reactive 
arylcyclobutene moieties. 
A particularly advantageous aspect of the present invention is the 
obtainment of the desirable physical property combinations in an easier 
fashion than those described in the art. A preferred aspect of the present 
invention is an improved process for preparing a blend of a first, high 
molecular weight branched carbonate polymer component and a second, lower 
molecular weight carbonate polymer component different from the first 
carbonate polymer component comprising the steps of (a) preparing a 
precursor component capable of forming the first high molecular weight 
branched carbonate polymer component, said precursor component comprising 
a carbonate polymer containing latent themally activated reactive 
moieties; (b) combining the precursor component with the second carbonate 
polymer; and (c) themally activating the latently reactive moleties of the 
precursor component to provide a generally homogeneous carbonate polymer 
blend composition. 
In a preferred process aspect, in step (b), the precursor component is 
combined with the second carbonate polymer component by (1) dry blending 
or dual feeding the precursor component with the second, lower molecular 
weight carbonate polymer component and then (2) melt blending the 
precursor and second components at a temperature and for a time less than 
sufficient to significantly thermally activate the latently thermally 
reactive moleties and (3) recovering an intermediate carbonate polymer 
blend composition comprising a precursor component having one or more 
latently reactive moleties. According to these processes, the precursor 
component comprising latent, thermally activated reactive moleties is 
intimately dispersed throughout the second carbonate polymer prior to or 
in conjunction with thermal activation of the latently reactive moiety and 
creates a high molecular weight branched carbonate polymer component in 
situ. In this way, carbonate polymer components of similar initial 
molecular weights can be more readily blended prior to the creation of the 
high molecular weight branched component. This will result in a better, 
more homogeneous mixture of the high molecular weight branched carbonate 
polymer component with the other carbonate polymer component. 
It has been surprisingly found that although the precursor carbonate 
polymer component with latent, thermally reactive moieties would have a 
tendency to form a highly crosslinked polycarbonate gel when reacted 
separately, when dispersed in a carbonate polymer composition prior to the 
activation of such moieties, undesirably large domains of highly 
crosslinked polymer gels are substantially reduced and preferably 
eliminated insofar as they produce undesirable effects in the physical, 
rheological, optical or surface aesthetic properties in molded articles. 
In other embodiments, the invention involves ignition resistant 
compositions which are optionally transparent and comprise: as a first 
component, a carbonate polymer drip reducing additive; as a second 
component, a second different carbonate polymer component; and, as a third 
component, other optional ignition resistance additives, wherein the 
ignition resistance of the blend composition, when tested according to UL 
94 attains at least a V-O rating at 1/8 inch or is more ignition 
resistant. Preferably, the carbonate polymer drip reducing additive is a 
high molecular weight branched carbonate polymer drip reducing additive 
which may be formed prior to or during ignition conditions. In other 
aspects, the invention involves improved processes for preparing fibers, 
blow molded or thermoformed parts, opaque parts having controlled gloss 
levels and transparent to translucent parts having controlled light 
diffusing properties. The parts and shaped articles that result are also 
aspects of this invention. 
As will be described in more detail below, the carbonate polymers according 
to the present invention have surprisingly improved combinations of 
physical properties, thermal stability, color, melt strength, transparency 
and processability. When shaped or molded into various types of articles 
the very desirable properties mentioned above are obtained. In addition, 
depending upon the molding or shaping method, light diffusing and/or 
surface altering effects may also be observed. In particular, the articles 
can be provided with a range of surface and light diffusing effects 
including transparency, translucence, high gloss, non-glare, low gloss, 
mottling, frosting or matte surface. 
DETAILED DESCRIPTION 
A key feature in preparing the compositions according to this invention is 
obtaining a suitable high molecular weight, branched carbonate polymer 
component ("HMWB PC") which is sufficiently stable and dispersible in the 
balance of the carbonate polymer composition. Preferably the HMWB PC is 
capable of providing a homogeneous mixture with the other carbonate 
polymer component in the claimed compositions without obtaining 
undesirable byproducts such as phase-separated very high molecular weight 
polymer, highly crosslinked gels or a very low molecular weight component 
and without the use of additional reactive additives such as free radical 
initiating compounds which can cause undesired degradation, color 
formation and/or uncontrolled crosslinking in the polymer composition or 
additives. Moreover, the use of free radical generating initiators is 
incompatible with the use of many of the known polymer stabilizing 
additives which are radical scavengers and are needed in carbonate 
polymers. 
As compared to similar types of materials that have been previously 
prepared or obtainable, it has been found to be important that the final 
high molecular weight branched component for use according to the present 
invention be themally stable at a temperature at least 100.degree. C., 
preferably at least 125.degree. C., more preferably at least 150.degree. 
C., above the Tg of the carbonate polymer blend composition. For the types 
of carbonate polymers that are most likely to be used as the lower 
molecular weight second component, such as the commercially available 
polycarbonate resins based on bisphenol A, the Tg is about 150.degree. C. 
Likewise, where the HMWB PC is based on bisphenol A, the Tg will be in the 
same range and the claimed blends based on such polymers will have a Tg in 
this range. Otherwise, where there is a difference between the Tg's of the 
two components that are combined and provided that the two components are 
sufficiently miscible to provide the homogeneous blends according to this 
invention, the resulting blend will have a single intermediate Tg. As used 
herein and well known to those skilled in the art, the term Tg refers to 
the glass transition temperature of the polymer or blend and is defined as 
the inflection point on the heat flow curve as determined by differential 
scanning calorimetry. 
It is therefore one of the novel and advantageous features of this 
invention to provide carbonate polymer blends of this type with a HMWB PC 
component that is themally stable during extended exposure to higher 
temperatures. This level of thermal stability can be determined by various 
known techniques such as by thermogravimetric analysis or by the 
measurement of color development or molecular weight change with 
increasing heat. Obviously, where the lower molecular weight second 
component (e.g., a commercially available polycarbonate resins based on 
bisphenol A) is determined or known to be sufficiently themally stable, 
thermal instability or stability of the HMWB PC can be determined based on 
thermal instability or stability of the blend. 
In particular, with regard to thermal stability, it is preferred that the 
compositions according to the present invention employ a high molecular 
weight branched component that maintains its molecular weight (after 
completion of any in situ forming reaction) upon heating in nitrogen to a 
temperature at least 100.degree. C., preferably at least 125.degree. C., 
more preferably at least 150.degree. C. above the Tg of the carbonate 
polymer blend composition. By the term maintains its molecular weight, it 
is meant that the HMWB PC does not contribute further significant 
molecular weight increases or decreases to the blend, preferably none of 
more than 10%, more preferably none of more 5% from its initial value. 
Preferably there is minimal color developed under these conditions, it 
being desirable to avoid the brown coloration that is observed when a 
carbonate polymer that is not thermally stable is heated to temperatures 
100 to 150.degree. C. above the Tg of the carbonate polymer. 
The high molecular weight branched carbonate polymers suitable for use as 
the first component in the compositions according to the present invention 
can be prepared by techniques known in the literature. In general, these 
carbonate polymers are prepared from one or more multihydric components by 
reacting the multihydric compound, such as a diphenol, with a carbonate 
precursor such as phosgene, a haloformate or a carbonate ester such as 
diphenyl- or dimethyl carbonate. Aromatic carbonate polymers are preferred 
and aromatic diphenols are preferred for use as at least part of the 
multihydric compound. Preferred diphenols include but are not limited to 
2,2-bis (4-hydroxyphenyl)-propane (i.e., bisphenol A), phenol, 
4,4'-(9-H-fluorene-9-ylidene)bis (i.e., bishydroxyphenylfluorene), 
4,4'-thiodiphenol (TDP), 1,1-bis (4-hydroxyphenyl)-1-phenyl ethane 
(bisphenol AP); phenolphthalein; bis (4-hydroxyphenyl) diphenyl methane; 
tetrabromobisphenol A (TBBA); and tetrachlorobisphenol A (TCBA). These 
carbonate polymers also include aromatic carbonate polymers prepared from 
two or more different dihydric phenols or a combination of a dihydric 
phenol and a glycol or a hydroxy- or acid-terminated polyester or a 
dicarboxylic acid in the event a carbonate copolymer or heteropolymer is 
desired. 
The high molecular weight branched carbonate polymers can be prepared from 
such materials by any of several known processes such as the known 
interfacial, solution or melt processes. Suitable types and amounts of 
chain terminators (typically monophenolic compounds) and or branching 
agents (typically phenols having three or more hydroxy groups) can be 
employed to obtain the desired molecular weight and branching degrees in 
the high molecular weight branched component. 
In general, by whatever production technique it is prepared, the high 
molecular weight, branched polymer should have a weight average molecular 
weight of at least about 3 times that of the second carbonate polymer, 
preferably at least about 5 times and more preferably at least about 10 
times. In order to obtain polymer blends with minimized levels of gels and 
other beneficial effects of the high molecular weight branched component, 
it has been found that the weight average molecular weight of the high 
molecular weight branched component should not be higher than about 200 
times that of the second carbonate polymer, preferably not higher than 
about 150 times, more preferably not higher than about 100 times, more 
preferably not higher than about 50 times. 
When using a linear carbonate polymer based on bisphenol A and having a 
weight average molecular weight in the range of 10,000 to 60,000, as the 
second, lower molecular weight carbonate component, it has been found that 
the weight average molecular weight of the high molecular weight branched 
component should be at least about 100,000, preferably at least about 
125,000, more preferably at least about 150,000. Correspondingly, in 
combination with second components of these types, the weight average 
molecular weight of the high molecular weight, branched component is 
generally less than about 2,000,000, preferably less than about 1,500,000, 
more preferably less than about 1,000,000. 
It has been found very advantageous to prepare suitable high molecular 
weight, branched carbonate polymer by using a precursor carbonate polymer 
component which has latently reactive moieties. These moleties should 
react with sites in the carbonate polymer or with one or more other 
latently reactive moieties to form the HMWB PC. These moleties can be 
incorporated into a carbonate polymer when that polymer is being initially 
polymerized or attached to the polymer in a later functionalization step. 
Preferably the precursor component latently reactive moieties, when they 
react primarily with one another, are capable of forming products having 
an average functionality greater than two. This means that for at least a 
portion of the moieties, more than two of the moleties react together and 
thus form branches from a polymer backbone chain. Latently reactive 
moleties forming products having an average functionality of two or less 
would produce only chain extension products without branches off the 
backbone. Preferably the selected latently reactive moieties can be 
rapidly activated, preferably themally, without the use of additional 
reactive compounds at a desired point (temperature/time history) in the 
blend preparation process and/or in the process for preparing shaped 
articles. Selection of a preferred latently reactive compound and 
avoidance of the additional reactive compounds produces a high molecular 
weight, branched carbonate polymer without producing undesired, low 
molecular weight byproducts or highly crosslinked polymer gels. Most 
preferably, such moiety can be incorporated into the carbonate polymer in 
an interfacial carbonate polymer polymerization process. 
As used herein, the term "interfacial carbonate polymer polymerization 
process" refers to a process where the multihydric reactants, including 
any multi- or mono-reactive compounds used to incorporate the latently 
reactive moiety, are dissolved in a water phase by forming an alkali metal 
adduct, then reacted with the carbonate polymer precursor forming a 
polymer which is dissolved in a separate organic phase. For example, 
dihydric phenols are dissolved as alkali metal phenates for reaction with 
the carbonate precursor forming an aromatic carbonate polymer which is 
dissolved in a separate organic phase. As those skilled in this area know, 
nitrogen-containing moieties, such as the unsaturated imido compounds of 
U.S. Pat. No. 3,652,715 and U.S. Pat. No. 3,770,697, cannot generally be 
present or incorporated in such a process and are therefore not suitable 
for use in this aspect of the present invention. 
According to a preferred aspect of the present invention, an intermediate 
composition is formed comprising a carbonate polymer precursor component 
having latently reactive moleties and a second carbonate polymer component 
having a lower molecular weight than the final high molecular weight 
branched component. Then, a high molecular weight, branched carbonate 
polymer is prepared without the use of added radical initiating compounds, 
or the like, merely by activation of the latently reactive moieties, 
preferably themally. As known in the art and shown in U.S. Pat. No. 
3,652,715 and U.S. Pat. No. 3,770,697, it is often necessary to 
incorporate reactive additives such as organic peroxides in order to 
initiate the reaction or addition polymerizing activity of functional 
moieties at sufficient rates. However, it is generally undesirable to 
incorporate chemicals of this type in molding resins due to the increased 
expense, possibility of volatile byproducts and deleterious residues. 
Therefore, the compositions according to the present invention, without 
such chemical initiator additives, offer an unexpected benefit in terms of 
being able to provide equivalent or better results in terms of ease of 
preparation, stability and performance of the resultant resins. 
As mentioned, in a preferred embodiment of the present invention, the 
latently reactive moieties are activated themally and at temperatures and 
other conditions below which any of the other carbonate polymers in the 
blend composition are degraded. By "thermally" or "heat" activated, it is 
meant that the reaction of the moiety with one or more other like moieties 
or reactive sites will occur at a reasonable rate upon bringing the 
composition to an elevated temperature but will not occur at a significant 
rate, preferably not at any measurable or rate, at ambient temperatures 
(i.e., below about 60.degree. C., preferably below about 50.degree. C.). 
With regard to the temperatures which are sufficient to initiate reaction 
at reasonable rates, these are preferably at least about the blend Tg, 
more preferably at least about 100.degree. C. above the blend Tg, most 
preferably at least about 150.degree. C. above the blend Tg. By 
"reasonable rate" it is meant that the reaction is essentially completed 
and the HMWB PC is themally stable within about 24 hours, preferably about 
10 hours, more preferably about 1 hour, most preferably about 0.25 hour 
after bringing the composition to the elevated temperature. 
It is also important to be able to themally activate such latent reactive 
moieties under conditions and particularly at temperatures below which any 
of the other carbonate polymers in the blend composition are degraded. The 
degradation conditions for a particular carbonate polymer, of course, 
depend somewhat on the exact composition of the carbonate polymer, 
including the particular multihydroxy compound(s) upon which it is based. 
For example, in the case of polycarbonates based on phosgene and bisphenol 
A, it has been found that unacceptable degradation begins to occur at 
temperatures on the order of about 400.degree. C. Therefore, themally 
activated latently reactive moieties for use with polycarbonates based on 
phosgene and bisphenol A should preferably be activated at temperatures 
below about 400.degree. C. 
A preferred technique to provide a precursor component with a suitable 
latent, themally reactive moiety is to utilize arylcyclobutene terminated 
carbonate polymers such as are shown in U.S. Pat. No. 5,198,527 and U.S. 
Pat. No. 5,171,824. It has been found that the arylcyclobutene terminated 
carbonate polymers are readily processable at standard carbonate polymer 
processing conditions and can be very readily combined with and thoroughly 
dispersed in a second carbonate polymer component across a range of 
molecular weights in the second component. As shown, the arylcyclobutene 
moieties can then be heat or thermally activated to combine via the 
arylcyclobutene moieties to produce the stable, high molecular weight, 
branched polymer component. These are especially preferred high molecular 
weight carbonate polymer components since the arylcyclobutene reaction 
does not require any free radical initiator or other activating compounds 
to initiate the addition reaction at reasonable temperatures and 
conditions for processing Bisphenol A-based polycarbonate. 
Moreover, the arylcyclobutene reaction is exceptionally clean in that it 
does not simultaneously produce any low molecular weight byproduct 
materials as are typically resulting from many of the carbonate polymer 
crosslinking reactions. The arylcyclobutene combination reaction is 
relatively quick and sufficiently selective to produce a high molecular 
weight, branched carbonate polymer during an extrusion or molding process 
employing the precursor polymer. In addition, it should be noted that 
substitution of the aryl ring of the arylcyclobutene compounds can be used 
to increase or decrease the reactivity of the cyclobutene group. 
In terms of the arylcyclobutene terminated carbonate polymers suited for 
use as the high molecular weight branched carbonate polymer component, it 
has been found desirable to incorporate the arylcyclobutene in amounts of 
at least about 0.01, preferably at least about 0.02, and most preferably 
at least about 0.03 mole arylcyclobutene moieties per mole diphenol 
monomer in the carbonate polymer to obtain suitable high molecular weight 
branched carbonate polymer components. Preferred arylcyclobutene 
terminated carbonate polymers suited for use as the high molecular weight 
branched carbonate polymer component would contain arylcyclobutene in 
amounts below that at which unacceptable levels of insoluble polymer gels 
are formed, desirably less than about 0.5, preferably less than about 0.4 
and more preferably less than about 0.3, and most preferably less than 
about 0.2 mole arylcyclobutene moieties per mole diphenol monomer in the 
carbonate polymer. 
Other latent, thermally reactive moieties suitable for use in preparing 
high molecular weight branched carbonate polymer components include, for 
example, cyanate, biphenylene, vinyl, propargyl, acrylic, methacrylic and 
allyl. 
It has been found that the desired combination of properties in the final 
blend composition together is affected by the three way combination of the 
molecular weight, the level of branching, and the amount of the high 
molecular weight, branched component. Therefore, these individual features 
depend upon the others and can vary across fairly broad ranges. In 
particular, the level of branching and the amount of the high molecular 
weight branched component are closely related, with higher levels of 
branching reducing the amounts of the component needed to provide a 
desired effect. 
In the case of latently reactive moieties in the precursor component, the 
amount of latently reactive moieties in the HMWB PC precursor can be 
expressed as the number of moles of reactive moiety per mole of diphenol 
in the precursor PC component. This is referred to as the mole per mole 
ratio or as "m/m". Then, the amount of latently reactive moieties in the 
mixture of the two PC components (prior to reaction of those moleties) can 
be calculated as the m/m ratio multiplied by the weight percent of the 
latently reactive precursor PC component in the mixture ("wt %"). In 
general, in the case of latently reactive moieties such as the 
arylcyclobutene moieties, it has been found that the latent reactive 
moiety concentration (which determines the amount of branching) and the 
amount of high molecular weight branched component should be selected such 
that the amount of latently reactive moieties in the mixture of the two PC 
components prior to their reaction (in units of m/m latent reactive moiety 
times wt % precursor component) should be greater than 0.05, preferably 
greater than 0.1, and most preferably greater than 0.15; and should be 
less than 2.0, preferably less than 1.75, and most preferably less than 
1.50. It is otherwise difficult to directly measure the degree of 
branching in the branched, high molecular weight component, especially 
when this component has been prepared in situ by activation of a latently 
reactive moiety. 
In general, however, it can be indirectly determined whether there is a 
sufficient degree of branching in the high molecular weight branched 
carbonate polymer by measuring the change in shear sensitivity due to the 
incorporation of the high molecular weight branched carbonate polymer in a 
carbonate polymer blend composition. It has been found that the high 
molecular weight branched component should have a degree of branching 
sufficient to provide an improvement or increase in the shear sensitivity 
of the resulting blend. In other words, the HMWB PC is sufficiently 
branched if it provides "shear thinning" in the final blend composition. 
This means that in the viscosities of the blend composition and the lower 
molecular weight carbonate polymer component alone are independently 
measured at increasing levels of shear, the measured viscosity of the 
claimed blend composition is observed to be reduced to a greater degree or 
at a greater rate than for the lower molecular weight carbonate polymer 
component without the high molecular weight branched component. It has 
been found that high molecular weight branched components with higher 
degrees of branching will provide shear sensitivity improvements at lower 
levels while lower degrees of branching will conversely require use of the 
component in larger amounts to provide shear sensitivity improvements. 
These measurements of shear sensitivity can be done by standard techniques 
with dynamic mechanical spectroscopy (DMS). 
In particular, a fairly standard measurement technique for shear 
sensitivity of carbonate polymers involves measuring the complex viscosity 
of a polymer (.eta.) under two different shear levels, 0.3 radians per 
second (lower shear) and 10 radians per second (higher shear) by dynamic 
mechanical spectroscopy at 280.degree. C. Then, the ratio of those two 
numbers is determined, .eta./.eta. (0.3/10). The value of the 
.eta./.eta. ratio for the linear polycarbonate control sample is taken as 
a baseline value of 1. Values of the .eta./.eta. ratio greater than 1.3, 
preferably greater than or equal to 1.5, more preferably greater than or 
equal to 2, show that there is an "improvement" or "increase" in shear 
sensitivity as that term is used herein. 
In general, the degree of branching can sometimes be directly determined in 
the high molecular weight branched carbonate polymer by measuring the 
concentration of reacted branching agent in an amount of the high 
molecular weight branched carbonate polymer prior to incorporation in the 
blend or that has been isolated from the carbonate polymer blend 
compositions according to the present invention. The concentration of 
reacted branching agent in the high molecular weight branched carbonate 
polymer can typically be determined by IR or NMR spectroscopy or by liquid 
chromatography, depending upon the nature of the branching agent. However, 
the lower levels of branching agent, although detectable by virtue of the 
shear sensitivity they impart, are very difficult to quantify by direct 
measurement techniques. 
As mentioned above, the desired combination of properties in the final 
blend composition together with the level of branching in the high 
molecular weight, branched component determine the level of high molecular 
weight, branched component in the carbonate polymers. According to the 
present invention a range of carbonate polymer blend compositions can be 
prepared to take advantage of the improved combinations of processability 
and improved properties obtainable in shaped articles. In general, it has 
been found suitable to employ the first high molecular weight branched 
component in the carbonate polymer blend compositions in amounts of at 
least about 0.1 weight percent, desirably at least about 1 weight percent, 
preferably at least about 2 weight percent and more preferably at least 
about 3 weight percent, said weight percentages being based upon total 
amount of the two carbonate polymer components in the blend compositions. 
In order to maintain processability and thermal plasticity, the high 
molecular weight, branched component is employed in amounts less than or 
equal to about 50 weight percent, preferably less than or equal to about 
35 weight percent, and more preferably less than or equal to about 25 
weight percent. 
When using arylcyclobutene terminated carbonate polymers as the precursor 
component for the high molecular weight branched carbonate polymer 
component, it has been found desirable to incorporate the 
arylcyclobutene-containing polymer in amounts sufficient to provide 
increased shear sensitivity in the resulting polymer. It is generally 
desired to employ such polymer in amounts of at least about 1, preferably 
at least about 2, more preferably at least about 3 and most preferably at 
least about 4 weight percent by weight arylcyclobutene-containing 
carbonate polymer in the preparation of composition according to the 
present invention. In general it has been found that the advantageous 
property combinations can be obtained using arylcyclobutene terminated 
carbonate polymers in amounts up to and including about 40, preferably up 
to and including about 30, more preferably up to and including about 25, 
and most preferably up to and including about 20 percent by weight based 
on the combined weight of the precursor and second carbonate polymer 
components. 
The carbonate polymers suitable for use as the second, lower molecular 
weight carbonate polymer component are generally well known in the 
literature and a large number are commercially available. In general, 
these are preferably carbonate polymers prepared from one or more dihydric 
components by reacting the dihydric compound, such as a diphenol, with a 
carbonate precursor such as phosgene, a haloformate or a carbonate ester 
such as diphenyl or dimethyl carbonate. Aromatic carbonate polymers are 
preferred and aromatic diphenols are preferred dihydric compounds with the 
preferred diphenols including but not limited to 
2,2-bis(4-hydroxyphenyl)-propane (i.e., bisphenol A); phenol, 
4,4'-(9-H-fluorene-9-ylidene)bis (i.e., bishydroxyphenylfluorene); 
4,4'-thiodiphenol (TDP); 1,1-bis (4-hydroxyphenyl)-1-phenyl ethane 
(bisphenol AP); phenolphthalein; bis (4-hydroxyphenyl) diphenyl methane; 
tetrabromobisphenol A (TBBA); and tetrachlorobisphenol A (TCBA). 
These lower molecular weight carbonate polymers can be prepared from such 
materials by any of several known processes such as the known interfacial, 
solution or melt processes. As is well known, suitable chain terminators 
(typically monophenolic compounds) can be employed to obtain the desired 
molecular weight in the lower molecular weight component. Optionally, 
branched carbonate polymers can be employed as the second, lower molecular 
weight carbonate polymer component. These products are known and are 
prepared using the typical branching agents such as multihydric compounds 
having three or more hydroxy groups, such as phenols having three or more 
hydroxy groups. Generally, however, the linear carbonate polymers are 
preferred for use as the second, lower molecular weight component where 
the improvement in shear sensitivity is more noticeable with addition of 
the high molecular weight branched component. 
The carbonate polymers suitable for use as the second, lower molecular 
weight carbonate polymer component in the present invention also include 
carbonate polymers prepared from two or more different multihydroxy 
compounds, preferably dihydroxy compounds, and preferably phenols, or a 
combination of a multihydroxy compound, such as a diphenol, and a glycol 
or a hydroxy- or acid-terminated polyester or a dicarboxylic acid in the 
event a carbonate copolymer or heteropolymer is desired. It is also 
possible to employ multifunctional carboxylic acids or derivatives, 
especially aromatic carboxylic acids including their acid chlorides, and 
prepare poly(ester-carbonate) resins such as the known aromatic 
poly(ester-carbonates) The known silicon-containing multihydric monomers 
can also be used to prepare silicon-containing carbonate polymers that are 
suitable for use in the blends according to the present invention. Also 
suitable for use as the second, lower molecular weight carbonate polymer 
components for practice of the invention are blends of two or more of the 
above-described lower molecular weight carbonate polymer components. 
For purposes of obtaining desired property combinations, it has been found 
that the second, lower molecular weight carbonate polymer component should 
have a weight average molecular weight of at least about 10,000, 
preferably at least about 13,000, more preferably at least about 15,000 
and most preferably at least about 17,000. In order to keep the desired 
level of polymer melt flow and processability it has been found that the 
second, lower molecular weight carbonate polymer component should 
preferably have a weight average molecular weight of no more than about 
60,000, preferably no more than about 55,000, more preferably no more than 
about 50,000, most preferably no more than about 40,000. 
It is understood that the second, lower molecular weight components 
suitable for use according to the present invention may be a single 
component carbonate polymer directly obtained from a polymerization 
process. On the other hand, commercially available carbonate polymers 
which will be suitable for use as the second, lower molecular weight 
component are often actually a combination of two or more different 
carbonate polymer components of differing molecular weights and melt flow 
rates. It is obviously necessary for carbonate polymer suppliers to 
provide the broad range of potential customers and applications with an 
equally broad range of different carbonate polymer products that vary in 
their balance of processability (i.e., melt flow rate) and performance 
properties. However, a polymerization facility can produce only a limited 
number of different polymers, typically near the higher and lower 
molecular weight extremes. These polymers are then blended to obtain the 
desired intermediate melt flow rate product. These types of products, will 
then have an average molecular weight which would then be determinative of 
their suitability for use as the lower molecular weight second carbonate 
polymer component in the blend compositions according to the present 
invention. It is also known that "branched polymers" such as the HMWB 
carbonate polymers used in the blends according to the present invention 
comprise only a portion of polymer molecules that are actually branched, 
the balance being essentially linear. However, as used herein, the term 
branched carbonate polymer refers to the entire polymer component and not 
just to the fraction of the molecules of that component that are actually 
branched. 
In preparing the blend compositions according to the invention it is 
important to employ mixing techniques that result in sufficient mixing of 
the two components, preferably obtaining a thorough, generally homogeneous 
mixing of the two components. Suitable processes are generally known to 
those skilled in this area, examples of techniques that can be used to 
homogeneously mix the first or precursor component with the second 
component include solution blending and melt blending in known melt mixing 
equipment such as single or twin screw extruders, molding equipment, 
Banbury mixers or the like. 
A further aspect of the invention, as mentioned above, is an improved 
process for preparing the disclosed carbonate polymer blends comprising 
the steps of (a) preparing a precursor component capable of forming the 
first high molecular weight branched carbonate polymer component, said 
precursor component comprising a carbonate polymer containing latent 
thermally activated reactive moieties; (b) combining the precursor 
component with the second carbonate polymer; and (c) themally activating 
the latently reactive moieties of the precursor component during or after 
their combination to provide a generally homogeneous carbonate polymer 
blend composition. 
The combination of the precursor and second components can be done by 
solution blending using known solvents and techniques. The first component 
precursor can also be combined with the second carbonate polymer by dry 
blending or dual feeding the precursor and second components. As known, 
dry blending involves combining and mixing the polymer in the form of 
powder, pellets, flakes or similar unmelted form. Dual feeding is 
performed using a K-tron brand feeder, a screw feeder, a weigh belt feeder 
or the like to separately convey the resins in an unmelted form to the 
inlet(s) or feed port(s) of a melt mixing device. Then, the dry mixture or 
dual feeds are supplied to an extruder or other melt mixing device. As 
noted, the combining step (b) can be done at a temperature and/or for a 
time sufficient for the latently themally reactive moieties to become 
significantly activated and reacted to form the HMWB PC component, 
providing the blend composition which can be used in appropriate 
applications. 
Another process aspect involves combining the precursor component in step 
(b) with the second carbonate polymer component at a temperature and for a 
time less than sufficient to significantly themally activate the latently 
thermally reactive moieties and (3) recovering an intermediate carbonate 
polymer blend composition. The intermediate resin blend would then contain 
both the the precursor component and the second carbonate polymer 
component. The intermediate could be further processed and/or shaped prior 
to, during or subsequent to the thermal activation of the latent reactive 
moieties. Another process aspect involves thermal activation of the 
latently reactive moieties of the precursor component in an extrusion or 
molding step to directly provide a shaped article prepared from the 
claimed carbonate polymer blend composition. 
In this way, this preferred process provides an intermediate carbonate 
polymer blend composition comprising a carbonate polymer precursor 
component having one or more latently reactive moleties which component is 
capable of forming a high molecular weight branched carbonate polymer upon 
heat activation and a second, different carbonate polymer component having 
a lower molecular weight than the high molecular weight branched 
component. A further preferred embodiment involves incorporating latently 
thermal reactive moieties in the first carbonate polymer component 
precursor in an interfacial polymerization process. 
In addition, when using a carbonate polymer precursor component that has 
latent reactive moieties and premixing the precursor with the second 
polymer component, it is important to perform the mixing under appropriate 
conditions to assure that there is good mixing of the polymers as the 
polymers melt. In particular, it is desirable if the molecular weights, 
and physical forms and sizes (i.e., pellets, flake, powder, etc.) of the 
polymers are selected to be within respective ranges so that both 
components begin to melt at about the same point in the melt mixing 
process. In this way, the precursor polymer will then be more 
homogeneously mixed to form a better intermediate. Otherwise, if preparing 
the high molecular weight branched component directly, the precursor 
polymer will then be more homogeneously mixed and dispersed by the time 
the themally activated latent reactive moieties began to inter-react. For 
example, if attempting to mix a powder form of precursor polymer with a 
pellet form of the second polymer component, the powder form precursor 
polymer may tend to melt more quickly and might begin inter-reaction prior 
to thorough melt mixing with the second component. Unless the process 
temperature is maintained sufficiently low, this may lead to undesirably 
large gels or domains of high molecular weight or crosslinked polymer. 
This can be prevented by using a second component which is similarly in 
powder form and/or has a lower molecular weight and/or lower glass 
transition temperature (Tg). 
The blend compositions according to the present invention are particularly 
well suited for applications that take advantage of the surprisingly good 
combinations of shear sensitivity, processability and melt strength. The 
blend compositions according to the invention exhibit a relatively high 
melt strength or high melt viscosity at low shear conditions and are 
unexpectedly easily processed at standard shear rates generated by typical 
melt processing equipment. This means that they are especially well suited 
for applications such as fiber forming, blow molding, thermoforming or 
profile sheet production where reasonably high melt strength is needed. 
In a related aspect, the present invention is also an improved process for 
preparing a fiber comprising the step of forming a fiber from a blend as 
described above, comprising the high molecular weight branched carbonate 
polymer component. Fiber forming process that can be applied to carbonate 
polymers are generally known to those skilled in the art and the use of 
the high melt strength carbonate polymer compositions according to the 
present invention provides an improvement in terms of melt strength, 
reduced necking and maintaining fiber diameter in very thin fibers. As 
also known to those skilled in the art, the term "fiber" when used in 
connection with carbonate polymers refers to strands that have a diameter 
of from about 0.1 to about 1.5 millimeter and a length of at least about 2 
millimeters. 
A further aspect of the blend compositions according to the present 
invention is the surprisingly good drip resistance under flame testing 
conditions, leading to the improved ignition resistance properties of 
these blends. One of the criteria in ignition resistance testing is 
resistance to the tendency to generate flaming drips of molten polymer 
under test conditions. In actual fire situations the molded plastic part 
is then believed to be less likely to spread a fire to other fuel sources. 
Polytetrafluoroethylene antidrip additives (Teflon) are known but their 
incorporation into carbonate polymers requires additional, complicated 
processing steps and has a detrimental effect on other polymer properties, 
particularly impact resistance and transparency. 
The polymer compositions according to the invention are surprisingly 
resistant to the dripping characteristic and can be advantageously used 
where ignition resistance properties are desired. Optionally, transparent, 
ignition resistant, carbonate polymer blend compositions can be obtained 
using a high molecular weight branched carbonate polymer drip reducing 
additive together with a second different carbonate polymer having a lower 
molecular weight than the high molecular weight branched component. It 
should be noted that other optional ignition resistance additives must be 
properly selected to maintain the desired levels of light transmission and 
haze if transparency is intended. These blends can be used to prepare 
improved shaped articles having good combinations of light transmission 
(transparency or translucency) and ignition resistance. Preferably, blends 
and articles can be prepared according to the invention wherein the 
ignition resistance of the blend, when tested according to UL 94 is rated 
at least V-O at 1/8 inch (3.175 mm) or is more ignition resistant (e.g., 
rated 5-V at 1/8 inch). In a another embodiment, the high molecular 
weight branched carbonate polymer drip reducing additive is formed under 
ignition conditions from a precursor component capable of forming a high 
molecular weight branched carbonate polymer upon heat activation. 
As mentioned, additional ignition resistance additives can be employed at 
appropriate levels where the desired levels of light transmission and low 
color are maintained. Such additives can include halogenated carbonate 
polymers and oligomers, such as brominated polycarbonates and 
oligocarbonates and inorganic and organic salts or alkali and alkali earth 
metals. 
A further aspect of the blends according to the present invention is that 
the high molecular weight branched component can be employed to provide 
light diffusing and gloss controlling effects, if such effects are desired 
and if appropriate processing conditions are employed. Many applications 
for opaque carbonate polymers, such as automotive parts, desire a 
controlled gloss or matte finish on the surface of the molded part. Other 
applications desire varying degrees of light transmission together with 
light diffusing effects. Such applications include frosted, mottled, 
semi-transparent or translucent parts like fluorescent lighting diffusers, 
shower doors and non-glare glazing for picture frames. 
It has surprisingly been found that the blends according to the present 
invention can produce such light diffusing or controlled gloss effects and 
maintain sufficient levels of light transmission. The amount of gloss 
reduction/light diffusion has been found to be a function of the amount of 
the high molecular weight branched component, particularly when a latent 
reactive arylcyclobutene moiety is being used to provide the branching. It 
has also been found that the use of high shear melt processing of the 
blend into molded parts, such as when injection molding, will provide the 
greatest reductions in the gloss and/or light diffusing effects in the 
parts. When a latent reactive arylcyclobutene moiety is being used to 
provide the branching, high shear melt processing of the blend into molded 
parts at or above temperatures required for thermal activation of the 
arylcyclobutene moiety provide the greatest reductions in the gloss and/or 
light diffusing effects in the parts. This reduces the need for special 
surface treatment of the molds or for subsequent surface treatment steps 
for the molded articles. 
As used herein, the term "reduced gloss" means that the incorporation of 
the high molecular weight branched component results in a molded article 
having lower gloss than an article molded under the same conditions from 
the same composition not containing the high molecular weight branched 
component. In general, "low gloss" polymer or resin, as used herein, 
refers to a polymer or resin, when molded into plaques and tested for 
gloss according to ASTM D-523-85 exhibits 60.degree. gloss values of less 
than about 70%, preferably less than about 60%. 
As used herein the term "transparent" means that molded articles have a 
measured total light transmission value according to ASTM D-1003 of at 
least about 40%, more preferably at least about 60%, more preferably at 
least 80% and a diffused light transmission value of less about 7%, 
preferably less than about 5%. As used herein the terms 
"semi-transparent", "frosted", "mottled" and "translucent" are generally 
synonymous and mean that molded articles have a measured diffused light 
transmission value according to ASTM D-1003 of at least about 7%, more 
preferably at least about 15% and most preferably at least about 20% and 
would have a total light transmission value of at least about 40%, more 
preferably at least about 50% and most preferably at least about 60%. 
Previously, in order to obtain light diffusion/reduced gloss effects in 
articles prepared from carbonate polymers that were transparent, 
semi-transparent or translucent it had been necessary to use additional 
process features or incorporate additives which had a detrimental effect. 
For example, when using a mold with roughened or embossed surface to 
provide such effects, the surface of the mold tends to wear out unevenly 
with time. Incorporating gloss reducing fillers normally causes the 
material to lose impact and light transmission properties. The present 
invention provides a composition and process that do not have these 
disadvantages and can produce these effects in shaped articles prepared by 
extrusion, blow molding, thermoforming or injection molding techniques 
with a smooth surface mold and without a subsequent gloss reducing surface 
treatment. Obviously further surface modifications can also be obtained 
using known surface treatments. 
In a further embodiment of the present invention, the controlled gloss, 
transparent, semi-transparent or translucent articles could also be 
obtained using another additive having sub-micrometer size particles at 
low levels such that the desired physical properties are not detrimentally 
affected while the desired light transmission and controlled gloss are 
obtained. 
A further aspect of the present invention is the ability to employ recycle, 
regrind, contaminated and/or scrap carbonate polymer as all or part of the 
second, carbonate polymer component and effectively upgrade those types of 
materials with the high molecular weight branched component. As known by 
the producers and users of thermoplastic carbonate polymers, the typical 
processes for preparing these polymers or resins and for preparing molded, 
extruded or otherwise shaped articles tend to produce varying amounts of 
recycle, regrind, contaminated and/or scrap carbonate polymer. As used 
herein, this refers to polymer or resin which has undergone a change or 
loss in the physical, rheological or optical properties versus the 
optimized properties typically possessed by the resin when it is initially 
extruded and pelletized. This degradation can be brought about by a number 
of conditions such as prolonged air exposure of the high temperature melt 
and repeated melt plastifications. 
As known, these conditions, particularly in the presence of contaminants or 
impurities such as pigments, paints, coatings and additives, can degrade 
the polymer molecular weight and cause change or loss of physical, 
rheological or optical properties. Typically, the recycle, regrind, 
contaminated and/or scrap carbonate polymer has been rejected for one or 
more of these reasons. The incorporation of the high molecular weight 
branched component, particularly by incorporation of a precursor 
component, either at the extruder or molding machine, can restore these 
properties and/or upgrade the resin to make it suitable for use in the 
same or different shaping processes. In general, it has been found that 
all or part of the second carbonate polymer in the compositions according 
to the present invention can be a recycle, regrind, contaminated and/or 
scrap carbonate polymer. In particular, the second carbonate polymer in 
the blends according to the present invention can employ at least about 5, 
preferably at least about 10 and more preferably at least about 30 weight 
percent recycle, regrind, contaminated and/or scrap carbonate polymer. 
In addition to the high and lower molecular weight components, and provided 
that the desired property combinations are maintained to a satisfactory 
degree, the carbonate polymer compositions according to the present 
invention can advantageously contain the standard types and amounts of the 
additive-type components frequently incorporated into carbonate polymers. 
These components can include ignition resistance additives, fillers (i.e., 
glass fibers, talc, clay, etc.), pigments, dyes, antioxidants, heat 
stabilizers, ultraviolet light absorbers, mold release agents, impact 
modifiers, antistatic additives, flow aids, lubricants, additive for 
reducing melt fracture and the other additives commonly employed in 
carbonate polymer compositions.

EXPERIMENTS 
The following Experiments are given to further illustrate the invention and 
should not be construed as limiting its scope. In the following 
Experiments, all parts and percentages are by weight unless otherwise 
indicated. 
Preparation of a Benzocyclobutene-terminated Polycarbonate ("BCB PC") 
Benzocyclobutene-terminated polycarbonates ("BCB PC"), precursor components 
having latently reactive arylcyclobutene moleties capable of forming a 
high molecular weight branched carbonate polymer upon heat activation, 
were initially produced by the following interfacial process. A glass 
reactor was fitted with a mechanical stirrer, a baffle, a thermometer, a 
pH electrode connected to a pH meter/controller, a liquid inlet tube, a 
gas inlet tube and a gas outlet tube connected to a phosgene scrubber, the 
scrubber containing an aqueous solution of 50 weight percent sodium 
hydroxide and about 1 percent by weight triethylamine. To the reactor was 
added 68.5 weight parts (0.3 mole parts) hisphenol A, 2.16 weight parts 
(0.018 mole parts) 4-hydroxybenzocyclobutene (BCB-OH), 360 weight parts 
water and about 240 weight parts dichloromethane. 
While stirring the reaction mixture there were added 48 weight parts (0.6 
mole parts) of sodium hydroxide in a 50 weight percent aqueous solution 
followed by the addition of 37 weight parts (0.375 mole parts) of gaseous 
phosgene at a rate of about 1 weight part per minute. The sodium hydroxide 
addition was maintained as needed to maintain a pH of about 12.5. 
Following the phosgene addition, 515 weight parts dichloromethane and 0.3 
weight parts (1 mole percent) triethylamine were added. The reaction 
mixture was agitated for 20 minutes to produce a hisphenol A polycarbonate 
resin terminated with benzocyclobutene moieties. The pH of the mixture was 
reduced to about 7 by the addition of 9 weight parts of phosgene. The 
polymer solution was washed with 1N HCl and with water and the polymer was 
then isolated. 
The polymer molecular weight was determined by gel permeation 
chromatographic (GPC) analysis, the weight average molecular weight (Mw) 
being 18,190. Liquid chromatographic analysis of the reaction mixture 
residue showed complete reaction of the 4-hydroxybenzocyclobutene. The 
resulting polycarbonate, before any crosslinking, was therefore determined 
to contain 0.06 moles benzocyclobutene per mole bisphenol A and have a 
degree of polymerization of about 27. 
The terminal location of the benzocyclobutene moleties was determined by 
reverse phase liquid chromatography using the conditions described by D. 
J. Brunelle et al., "Remarkable Selective Formation of Macrocyclic 
Aromatic Carbonates: Versatile New Intermediates for the Synthesis of 
Aromatic Polycarbonates", J. of Am. Chem. Soc. (1990) vol 112, p. 2399. A 
bonded silica column using tetrahydrofuran/water gradient was employed to 
separate oligomer components. Their retention times and UV spectra were 
compared to determine the types of oligomer end groups. 
Using the process as described above and adjusting the amounts of aqueous 
sodium hydroxide, water, phosgene and methylene chloride, two additional 
arylcyclobutene terminated aromatic carbonate polymers were prepared 
having the molecular weights and arylcyclobutene concentrations as shown 
in Table I. In Table I the ratio of the moles hydroxybenzocyclobutene to 
the moles of bisphenol A in the polymer is shown as "Mole Ratio." As shown 
in Table I, varying the amounts of BCB-OH results in the indicated range 
of polymer compositions and molecular weights. The table shows molecular 
weight (Mw) of the resulting BCB PC which is the precursor to the high 
molecular weight branched carbonate polymer (HMWB PC) as well as the 
molecular weight of the HMWB PC component that resulted from reaction of 
that BCB PC. 
The Mw of the resulting HMWB PC was determined by GPC analysis of the 
molecular weight distribution of blend compositions after the BCB PC had 
been fully reacted to form the HMWB PC. For the purposes of these tests, 
20 weight percent of the 0.03 m/m BCB PC was blended with 80 weight 
percent of a 20 MFR linear PC, while 7 and 3.5 weight percentages of the 
0.06 and 0.1 m/m BCB PC's, respectively, were blended with the balance of 
a 13 MFR PC resin. Then, the latently reactive BCB moleties of the 
precursor component were thermally activated to provide a homogeneous 
carbonate polymer blend composition containing the HMWB PC. The blend was 
analyzed by GPC and the high molecular weight portion of the molecular 
weight distribution curve was mathematically analyzed to determine the Mw 
of the HMWB PC component. 
TABLE I 
______________________________________ 
High Molecular Weight Branched 
Polycarbonates ("HMWB PC") 
Mw 
Branching Agent Before Reaction 
After Reaction 
No. Type (Mole Ratio) 
(Precursor) 
(HMWB PC) 
______________________________________ 
A BCB 0.03 31,894 99,100 
B BCB 0.06 18,190 676,500 
C BCB 0.1 11,634 234,000 
______________________________________ 
These or similar BCB PC polymers were used to prepare the HMWB PC 
components in the blends prepared below. 
Table II below summarizes the series of second, lower molecular weight 
polycarbonate resins that are used in preparing the example and comparison 
blend compositions. 
TABLE II 
______________________________________ 
Lower Molecular Weight Polycarbonates 
No. Type Mw MFR 
______________________________________ 
I Linear 36,000 3.5 
II Linear 32,000 6 
III Linear 26,500 13 
IV Linear 24,000 20 
V Linear 19,000 60 
VI Linear 18,000 80 
VII Branched 36,000 2.5 
______________________________________ 
The blend compositions that are shown in the following tables were prepared 
as indicated. The HMWB PC component precursors based on the BCB PC used in 
these and subsequent experimental compositions was observed to have 
blended homogeneously with the second component. Also, in the final 
products, the HMWB PC components based on the BCB PC were observed to form 
homogeneous blends with no visually observable phase separated components 
in the resulting blend compositions. Analysis of the mixtures for 
insoluble crosslinked polycarbonate gave 3 percent or less by weight. For 
all of the blends shown in the tables, the Tg was about 150.degree. C. 
Then, as shown, parts were successfully molded from the blend compositions 
and were tested according to the indicated methods with the results 
reported below. 
For measurement of the "Melt Strength" the following test was used, as 
described in U.S. Pat. No. 5,094,806. ASTM Type I tensile bars (see ASTM 
designation D 638-87b) are prepared by injection molding on a 70 ton 
Arburg molding machine. Mold temperatures in the range of 150.degree. 
F.-175.degree. F. (65.degree.-80.degree. C.), are used in molding the 
tensile bars from the various compositions. Various amounts of weight are 
attached to one of the ends of each of the predried tensile bars and the 
bars are hung vertically in a forced air oven for 5 minutes at a 
temperature of about 200.degree. C. or 175.degree. C. (as indicated in the 
respective table), which is about comparable to the melt temperature at 
which these compositions would be blow molded. The weight reported as the 
"melt strength" or "Equil. Load (Grams)" for each sample is the amount of 
weight which could be attached to the bar before it showed any detectable 
elongation under these conditions at the selected temperature. The 
dramatic increase in the amount of weight which a tensile bar can support 
without elongation at elevated temperatures, resulting from the presence 
of a high molecular weight branched polymer component, can be clearly seen 
from the following data. 
As used herein the term "DTUL" is the deflection temperature under a load 
of 264 psi as measured according to ASTM D 648-82. Flexural modulus is 
measured according to ASTM D 790-84a and the tensile strength and the 
elongation are measured according to ASTM D 638-84. Where reported, the 
notched Izod impact strength is measured on a test bar sample having 
dimensions of 1/2 inch by 2 1/2 inches (12.7 mm by 63.5 mm) and having a 
notch of 10 mil (0.0254 mm) according to ASTM D 256-84. The melt flow rate 
(MFR) values are measured according to ASTM D 1238-85, conditions of 
300.degree. C. and 1.2 kilograms mass and are reported in grams per 10 
minutes (gr/10 min). 
Melt Strength of Blend Compositions 
Blend compositions were prepared as indicated in Table III below containing 
a lower Mw base PC resin in powdered form and a BCB PC component (in flake 
form) to provide the HMWB PC. The indicated components were dry blended, 
then melt mixed on a 1 1/2 inch (38 mm) single screw Killion extruder at a 
temperature of about 430.degree. F. (220.degree. C.) and pelletized. At 
this point the BCB moleties were not yet significantly reacted and the 
HMWB PC was not yet formed. The intermediate blend composition obtained 
can be further processed, by injection molding, for example, into shaped 
articles. The HMWB PC component can then be obtained prior, during or 
subsequent to the processing into the desired shaped article. For the melt 
strength test samples, the BCB PC was then reacted to form the HMWB PC 
during the injection molding step when the blend composition was injection 
molded into test bars at a temperature of about 305.degree. C. 
TABLE III 
__________________________________________________________________________ 
Blend Composition Melt Strength 
HMWB PC Product Melt Strength 
Blend 
(BCB-TYPE) Lower Mw Base PC 
Equil. Load 
Comp. Mole Type 
PC (Grams) 
No. Wt % 
% BCB 
Mw** 
Wt % 
*** MFR Mw at 200.degree. C. 
__________________________________________________________________________ 
1* 0 -- -- 100 Lin 13 26,500 
2 
2* 0 -- -- 100 Lin 3.5 36,000 
12 
3* 0 -- -- 100 Br 2.5 36,000 
36 
4 5 0.06 18,000 
95 Lin 13 26,500 
56 
5 7 0.06 18,000 
93 Lin 13 26,500 
116 
6 9 0.06 18,000 
91 Lin 13 26,500 
200 
7 3.5 0.1 11,000 
96.5 
Lin 13 26,500 
50 
8 5 0.1 11,000 
95 Lin 13 26,500 
76 
__________________________________________________________________________ 
*Not an example of the present invention 
**As measured before reaction 
***Lin = linear, Br = branched 
As can be seen, the blend compositions according to the invention have 
improved melt strength properties over the linear PC base resin and over a 
branched PC resin not containing a high molecular weight branched 
carbonate polymer component. 
Ignition Resistance of Blend Compositions 
A blend composition was prepared comprising 5 percent by weight of a first, 
high molecular weight branched component based on flake BCB PC (0.1 m/m 
BCB, 10,000 mol wt) and 95% by weight of a second, lower molecular weight 
polycarbonate component of powdered polycarbonate having a molecular 
weight of 26,500. These components were initially dry blended as powders 
and extruded at 280.degree. C. on a 30 millimeter Werner and Pfleiderer 
(WP) twin screw extruder and pelletized. At this point the BCB PC was 
found by liquid chromatographic analysis to be partially reacted, forming 
a portion of the high molecular weight branched component by the heat 
treatment. 
To this blend composition were added the following ignition resistance 
additives: (0.1% by weight potassium N-(p-tolylsulfonyl)-p-toluene 
sulfimide (KPTSM), 0.1% by weight hydrogen N-(p-tolylsulfonyl)-p-toluene 
sulfimide (HPTSM) 1.0% by weight BC-52 brand brominated oligocarbonate. 
The additives were incorporated by blending and extruding at 311.degree. 
C. on a 30 mm WP twin screw extruder. At this point the BCB PC was found 
to be fully reacted to have formed the high molecular weight branched 
component by the heat treatment. This composition was molded into test bar 
samples at 340.degree. C. on a 70 ton Arburg molding machine at a mold 
temperature of 180.degree. F. (82.degree. C.). The HMWB PC component was 
observed to have blended homogeneously with the second component. These 
samples were then evaluated and the following properties were observed: 
TABLE IV 
______________________________________ 
Ignition Resistant Composition Properties 
______________________________________ 
Izod (10 mil notched) 15.2 ft lbs 
(800 J/m) 
Izod (unnotched, weldline) 
no break 
Tensile strength (at break) 
9071 psi 
(64MPa) 
Elongation (at break) 90% 
UL-94 rating at 1/16 inch 
V-0 
(1.6 mm) 
______________________________________ 
This composition is an improvement over compositions which utilize Teflon 
as an antidrip agent to obtain V-O rating since the use of Teflon produces 
an opaque blend and results in a loss of impact properties. 
Controlled Gloss Compositions 
The compositions shown in Table V were prepared by dry blending the 
indicated powdered linear PC and flake BCB PC components and melt mixing 
on a 30 mm co-rotating twin screw WP extruder at 230.degree. C. and 
recovering the pelletized intermediates with the HMWB PC not believed to 
be significantly formed. Test plaques were then molded on a 70 ton Arburg 
injection molding machine at 320.degree. C. with a mold temperature of 
150.degree. F. This process provided moderate to high shearing during the 
melt extrusion and flow into the mold. The gloss measurements are 
performed according to ASTM D-523-85 using a Dr. Lange Reflectometer RB3 
model test apparatus from Hunter Associates. 
TABLE V 
______________________________________ 
Controlled Gloss Properties Comparison 
Composition No. 9* 10 
______________________________________ 
PC (21,000 mol wt, 
2000 gm 1800 gm 
linear) 
BCB-PC (18,000 mol wt)** 
0 200 gm 
Carbon black 4 gm 4 gm 
Properties 
20.degree. gloss 85 6 
60.degree. gloss 101 20 
85.degree. gloss 99 53 
Izod (10 mil Notched) 
2.5 ft/lbs 10 ft/lbs 
(132 J/m) (535 J/m) 
______________________________________ 
*Not a sample of the present invention 
**Prior to reaction; 0.06 Mole/Mole BCB 
As can be seen, the added HMWB PC provided excellent gloss reduction while 
actually improving the product toughness. 
Translucent Compositions 
The following compositions were prepared and tested for translucence. In 
preparing the Blend No. 11 formulation, 72.2 weight percent of the 18,000 
Mw linear PC pellets and 27.8 weight percent of powdered 26,500 Mw linear 
PC were dry mixed, extruded on a Werner and Pfleiderer 30 mm co-rotating 
twin-screw extruder at 230.degree. C. and pelletized. In preparing the 
Blend No. 14 formulation, 65 weight percent of the 18,000 Mw PC pellets, 
25 weight percent of powdered 26,500 Mw linear PC and 10 weight percent of 
the 18,000 Mw (0.06 m/m) BCB-PC flake were mixed in the same fashion as 
was used to prepare Composition 11. In preparing blend formulations 
numbered 12 and 13 in the following Table VI, 75 and 50 weight percent, 
respectively, of the 18000 Mw linear PC were combined with a premix of 25 
and 50 weight percent respectively of Blend No. 14 by dry blending at the 
molding machine. 
Blend No. 15 was prepared in the same fashion as Blend 11 using 90 weight 
percent of the 21,600 Mw branched PC pellets and 10 weight percent of the 
18,000 Mw (0.06 m/m) BCB-PC flake. For the Blend No. 16 formulation, 60 
weight percent of the 18000 Mw linear PC pellets, 20 weight percent of 
powdered 26,500 Mw linear PC and 20 weight percent of the 18,000 Mw (0.06 
m/m) BCB-PC flake were blended using the same process as used with Blend 
11. 
The compositions were dried at 120.degree. C. for 4 hours prior to molding 
on a 70 ton Arburg molding machine set at 305.degree. C. A smooth surfaced 
ASTM mold set at 175.degree. F. (80.degree. C.) was used to mold 2.5 inch 
(63.5 mm) disks, tensile bars and DTUL bars which were evaluated as 
removed from the mold without any subsequent gloss reducing surface 
treatment. The following measurements were made on a Color Quest 
instrument from Hunter Associates Laboratory according to ASTM D-1003. As 
used in Table VI, these terms have the indicated meanings: 
Diffuse Transmission: Process by which incident light, while being 
transmitted through an object, is redirected or scattered over a range of 
angles. 
Regular Transmittance: Process by which incident light is transmitted 
through an object in a linear, straight through manner, without diffusion. 
Total Transmission: Diffuse Transmission+Regular Transmission 
##EQU1## 
TABLE VI 
__________________________________________________________________________ 
Translucent Properties 
HMWB 
PC Transmittance Properties 
Blend 
(BCB PC) 
Lower Mw Base PC 
Total 
Diffused 
Haze 
UL-94 
No. Wt % Wt % 
Type 
Mw (%) (%) (%) (1/8 inch 
__________________________________________________________________________ 
11* 
0 72.2 
Lin 18,000 
89.9 
0.8 0.9 Fail 
27.8 
Lin 26,500 
12 2.5 91.25 
Lin 18,000 
86.9 
27.9 31.9 
V-2 
6.25 
Lin 26,500 
13 5 82.5 
Lin 18,000 
88.3 
40.3 45.4 
V-0 
12.5 
Lin 26,500 
14 10 65 Lin 18,000 
86.5 
55.0 63.6 
V-0 
25 Lin 26,500 
15 10 90 Br 21,600 
86.7 
54.1 62.3 
V-0 
16 20 60 Lin 18,000 
77.3 
58.2 75.2 
Fail 
20 Lin 26,500 
__________________________________________________________________________ 
*Not an example of the present invention. 
As can be seen, the HMWB PC component results in large increases in the 
light diffusing properties of these compositions. Surprisingly, there is 
additionally a simultaneous improvement in ignition resistance for most of 
the compositions. In comparing the effects of a HMWB PC to a lower 
molecular weight branched PC with regard to light diffusing ability and 
melt strength, various compositions were evaluated as shown in Table VII. 
For Composition No. 18*, 95 weight percent of the 18,000 Mw linear PC 
pellets and 5 weight percent of 36,500 Mw branched PC were dry mixed and 
extruded on a Werner and Pfleiderer 30 mm co-rotating twin-screw extruder 
at 235.degree. C. and pelletized. In preparing Composition No. 19*, 90 
weight percent of the 18,000 Mw linear PC and 10 weight percent of 36,500 
Mw branched PC were dry mixed and extruded on a Werner and Pfleiderer 30 
mm co-rotating twin-screw extruder at 240.degree. C. and pelletized. In 
preparing Composition No. 20, 95 weight percent of the 18000 Mw linear PC 
and 5 weight percent of 18,000 Mw BCB-PC flake were dry mixed and extruded 
on a Werner and Pfleiderer 30 mm co-rotating twin-screw extruder at 
230.degree. C. and pelletized. In preparing Composition No. 21, 90 weight 
percent of 18000 Mw linear PC pellets and 10 weight percent of 18,000 Mw 
BCB-PC flake were combined according to same process as used for 
Composition No. 20. 
The compositions were all dried at 120.degree. C. for four hours prior to 
molding on a 70 ton Arburg molding machine at 310.degree. C. A smooth ASTM 
mold set at 175.degree. F. (80.degree. C.) was used to mold 2.5 (63.5 
mm)inch disks, tensile bars and DTUL bars. The light transmission tests 
were the same as performed for the preceding Table VI compositions. The 
melt strength tests were the same as performed above for the Table III 
compositions but at 175.degree. C., a slightly lower temperature. 
TABLE VII 
__________________________________________________________________________ 
Higher versus Lower Mw Branched PC 
Melt Strength 
Comp. 
Branched PC 
Light Transmission Properties 
Equil. Load (Grams) 
No. Wt % 
Type Total (%) 
Diffuse (%) 
Haze (%) 
at 175.degree. C. 
__________________________________________________________________________ 
17* 0 -- 88.5 0.4 0.4 0 
18* 5 Low Mw 
89.7 0.6 0.5 1 
19* 10 Low Mw 
90.5 1.0 1.1 5 
20 5 High Mw 
89.1 7.3 8.2 60 
21 10 High Mw 
86.4 49.9 57.8 &gt;635 
__________________________________________________________________________ 
*Not an example of the present invention. 
As can be seen, the HMWB PC provides much larger benefits than lower 
molecular weight branched PC with regard to both light diffusing 
properties and melt strength. 
Blend Composition Thermal Stability Evaluation Heat testing a blend of a 
HMWB PC (based on BCB PC) with a lower molecular weight polycarbonate 
shows that the BCB PC based materials provide HMWB PC components with 
excellent thermal stability as shown in Table VIII below. These tests were 
conducted on polymer films prepared from dichloromethane solutions of a 
blend comprising 20 wt. % 0.06 m/m BCB PC and 80 wt. % of an MFR linear 
PC. The blends were prepared by solution blending the components in the 
dichloromethane at room temperature with the HMWB PC being formed by the 
reaction of the BCB during a 6 minute heating period up to 300.degree. C. 
The blends all had Tg values of about 150.degree. C. 
The film samples of the alloys and PC controls were exposed to heating at 
300.degree. C. under nitrogen for the indicated times and analyzed by GPC 
for molecular weight (Mw or weight average, Mn or number average, and Mz 
or "z" average), by UV spectrophotometry for total absorbance at 288 nm 
("Abs. 288 nm"), and visually for color (see Table VIII). Heating the 
control PC for 40 min. at 300.degree. C. produced no significant change in 
molecular weight or color. The BCB PC/PC blend showed a rapid increase in 
molecular weight as the BCB PC fraction reacts to form the HMWB PC, after 
which the polymer molecular weight does not significantly change (less 
than 5% change in Mw). The color of the BCB PC/PC alloy remains low 
throughout the test, becoming slightly yellow, but not dark or brown in 
color. It can therefore be seen that these HMWB PC components and the 
resulting blend compositions according to the invention are themally 
stable at a temperature 100.degree. C. above the Tg of the carbonate 
polymer blend composition, which was about 150.degree. C. in this case. 
TABLE VIII 
__________________________________________________________________________ 
Carbonate Polymer Heat Stability Properties 
Min @ Abs. 
Polymer 300.degree. C. 
Mn Mw Mz disp 
288 nm 
Color 
__________________________________________________________________________ 
No. 22* 0 11392 
26217 
39891 
2.30 
100 clear 
13.5 MFR 
40 12414 
29270 
70477 
2.36 
175 clear 
Lin PC 
No. 23 0 8045 18749 
34974 
2.33 
106 clear 
80% Lin PC 
3 8453 20460 
52757 
2.42 
204 clear 
(80 MFR)/20% 
6 9144 31891 
130553 
3.49 
287 clear 
HMWB PC 10 9676 33039 
128080 
3.41 
250 clear 
20 8760 31587 
152227 
3.61 
431 light 
40 9243 30777 
125220 
3.33 
386 yellow 
__________________________________________________________________________ 
*Not an example of the present invention. 
Effects of Various Molecular Weights and Branching Degrees in the HMWB PC 
The compositions shown in Table IX were prepared by solution mixing of the 
indicated BCB PC with a 22 MFR linear PC in dichloromethane at room 
temperature followed by precipitation with hot water 
(90.degree.-100.degree. C.) followed by compression molding starting at 
200.degree. C. and heating to 300.degree. C. The BCB PC was reacted to 
form the HMWB PC during this molding. The HMWB PC components were prepared 
from the indicated BCB PC's (from Table I). 
As can be seen in Table IX below, the higher concentrations of the HMWB PC 
component (the greater degrees of branching) significantly increase the 
low shear viscosity (decrease the melt flow rate) of the compositions 
prepared. 
TABLE IX 
______________________________________ 
Effect of HMWB PC Molecular Weight on Blend MFR 
(22 MFR PC) 
Wt. % Wt. % % 
m/m BCB BCB PC BCB Total 
No. BCB in BCB PC in Blend (m/m .times. wt %) 
MFR 
______________________________________ 
24* -- -- 0 -- 22 
25 0.03 1.40 6.00 0.08 22.5 
26 0.03 1.40 14.00 0.20 13.4 
27 0.03 1.40 20.00 0.28 8.1 
28 0.06 2.75 3.00 0.08 21.6 
29 0.06 2.75 7.00 0.19 6.1 
30 0.06 2.75 10.00 0.28 2.7 
31 0.1 4.51 1.50 0.07 24.5 
32 0.1 4.51 3.00 0.14 4.4 
33 0.1 4.51 7.00 0.32 &gt;0.5 
34 0.1 4.51 10.00 0.45 &gt;0.5 
______________________________________ 
*Not an example of the present invention. 
In Table X it is is shown that blends based on HMWB PC improved in melt 
strength (Equil. Load) as shown by the increased loads that can be 
supported and Shear Sensitivity (processability) as shown by the lower 
.eta./.eta. ratio while they maintained their toughness. The blends of 
Table X were prepared by the process described above and used for 
preparing the blends of Table III. 
The shear sensitivity measurements for the polymers of Tables X and XI were 
done by dynamic mechanical spectroscopy (DMS), as mentioned above. The 
viscosity (.eta.) of the polymer was measured under two different shear 
levels, 0.3 radians per second (lower shear) and 10 radians per second 
(higher shear) by dynamic mechanical spectroscopy at 280.degree. C. Then, 
the ratio of those two numbers is determined, .eta./.eta. (0.3/10). The 
value of the .eta./.eta. ratio for the linear polycarbonate control sample 
was then taken as a baseline value of 1. The .eta./.eta. ratios for the 
other sample were converted to comparable values by dividing by the value 
of the .eta./.eta. ratio for the linear polycarbonate control sample. 
Values of these .eta./.eta. ratios greater than 1, preferably greater than 
or equal to 1.5, more preferably greater than or equal to 2, show that 
there is an "improvement" or "increase" in shear sensitivity as that term 
is used herein. The values for shear sensitivity, .eta./.eta. (0.3/10), 
are a unitless ratio of the viscosity measurements as determined by 
dynamic mechanical spectroscopy at 280.degree. C. 
TABLE X 
__________________________________________________________________________ 
Effect of HMWB PC Concentration on Rheological 
and Impact Properties 
HMWB PC Base PC Blend Properties 
Wt. Wt. % 
Wt. % Equil. 
Shear sensitivity 
Izod impact 
% in 
m/m Wt % 
BCB in Load at 
.eta./.eta. 
ft. lb./in. 
No. 
Blend 
BCB BCB in Blend 
Blend 
MFR MFR 200.degree. C. (g) 
(0.3/10) (J/m) 
__________________________________________________________________________ 
35* 
-- -- -- -- 100 13.0 
13 2 1.00 17 
(900) 
36 5.0 0.06 
2.75 
0.14 95 13.0 
4.4 56 1.56 16 
(850) 
37 7.0 0.06 
2.75 
0.19 93 13.0 
1.5 116 1.92 15 
(800) 
38 9.0 0.06 
2.75 
0.25 91 13.0 
1.1 200 2.22 16 
(850) 
__________________________________________________________________________ 
*Not an example of the present invention. 
The samples shown in Table XI were prepared by solution blending the 
components in dichloromethane precipitation in hot water. In Table XI it 
is is shown that blends based on 200,000 Mw linear PC were not 
significantly improved in processability as shown by the lower .eta./.eta. 
ratio (improved shear sensitivity). In Table XI, the high molecular weight 
PC is linear and has an Mw of 200,000 and the MFR was not measurable. 
TABLE XI 
______________________________________ 
Effect of High Molecular Weight PC on 
PC Shear Sensitivity 
High Molecular 
Shear 
Base PC Weight PC sensitivity 
No. Wt. % Mw MFR Wt. % Mw .eta./.eta. (0.3/10) 
______________________________________ 
39* 100 26,500 13 0 200,000 
1 
40* 95 26,500 13 5 200,000 
1.20 
41* 91 26,500 13 9 200,000 
1.27 
______________________________________ 
*Not an example of the present invention. 
As understood by those skilled in this art, there are many other 
embodiments of the invention in addition to these represented above. These 
examples, therefore, cannot be construed as limiting the scope of this 
invention in any way.