Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2002-10-02
2004-08-24
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S025000, C528S204000, C525S464000
Reexamination Certificate
active
06780956
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to silicone copolycarbonates suitable for use in molded articles such as optical articles, methods for making such silicone copolycarbonates and methods for controlling the physical properties of silicone copolycarbonates. Material properties of silicone copolycarbonates are found to be controlled both by composition and method of preparation. Control of product properties by method of preparation is provided by three methods which provide identically constituted materials having different physical properties. This invention further relates to optical articles, and methods for making optical articles from the silicone copolycarbonates.
BACKGROUND OF THE INVENTION
The past two decades have seen tremendous growth in the use of optical plastics in information storage and retrieval technology. Polycarbonates and other polymer materials are utilized widely in optical data storage media, such as compact disks. In optical data storage applications, it is desirable that the plastic material chosen have excellent performance characteristics such as high transparency, low water affinity, good molding characteristics, substantial heat resistance and low birefringence. Low water affinity is particularly desirable in optical data storage media applications in which disk flatness is affected by water absorption. In “read through” applications successful employment of a particular optical plastic requires that it be readily molded into disks embossed with a series of very fine grooves and pits which govern critical aspects of data storage and retrieval. Replication of these grooves and pits during molding must occur with high precision and a high level of disk to disk uniformity must be achieved. Moreover the material itself must not stick to or foul the mold surfaces. Water affinity, molding characteristics, thermal and optical properties are properties of the material itself and will ultimately depend upon the structure of the optical polymer. Efforts to maximize desirable properties and repress undesirable properties in optical polymers have been intense. The chief means of discovery in this area has been through chemical synthesis and testing of new materials. Many different polymer types and structures have been prepared and evaluated. However, because each new application may require a different balance of material characteristics not currently provided by known materials, efforts directed to the discovery of new polymers has continued.
Silicone copolycarbonates, while as a class exhibiting poor miscibility of the silicone and polycarbonate repeat units and a marked tendency toward segregation into predominantly silicone-containing and polycarbonate-containing phases, are prized for their low temperature ductility and moldability. It has been discovered that the physical properties of silicone copolycarbonates may be controlled by controlling the molecular architecture of said silicone copolycarbonates. This control of the physical properties by controlling molecular architecture supplements the control over physical properties which may be exercised by changing the composition of the silicone copolycarbonate.
SUMMARY OF THE INVENTION
The present invention relates to a method of preparing a silicone copolycarbonate having a molecular architecture which comprises a combination of random and blocky substructures. More particularly the method of the present invention relates to a method of preparing silicone copolycarbonates, said silicone copolycarbonates comprising both random and blocky substructures, said method comprising:
Step (A) preparing in a first step an intermediate silicone copolycarbonate, said intermediate silicone copolycarbonate having a random or a blocky structure; and
Step (B) reacting said intermediate silicone copolycarbonate in a second step which compliments the first step in that whichever structure, random or blocky, the silicone copolycarbonate intermediate has, a product formed in the second step will have both a random substructure and a blocky substructure.
This invention further relates to methods of controlling the physical properties of silicone copolycarbonate products made by the method of the present invention by controlling the relative amounts of random and blocky substructures present in said products. Thus, the physical properties of identically constituted silicone copolycarbonates may be controlled by choice of preparation method. Silicone copolycarbonates may be prepared by one of several methods which in turn provide products having varying amounts of random and blocky substructures. In “Method 1” interfacial polymerization of the starting monomers with phosgene affords a product having an entirely blocky structure and higher glass transition temperature than an identically constituted product produced by “Method 2” which produces a product silicone copolycarbonate having an entirely random structure. In Method 2, reaction of an oligomeric, non-silicone-containing bischloroformate with a silicone-containing bisphenol affords a product with a random structure and glass transition temperature lower than an identically constituted product produced by Method 1. Silicone copolycarbonates produced by Method 1 and Method 2 have molecular architectures which are entirely blocky or entirely random. Silicone copolycarbonates produced by Method 1 and Method 2 are considered to possess but a single substructure which is which is either random or blocky. One aspect of the present invention relates to the discovery of a third method, “Method 3”, of preparing silicone-containing copolycarbonates which affords a product silicone copolycarbonate possessing a molecular architecture comprising both random and blocky substructures. Method 3, as disclosed herein, is a hybrid of methods 1 and 2 and is referred to as a hybrid method. Moreover, the molecular architecture comprising both random and blocky substructures provided by the application of Method 3 is referred to as “hybrid” molecular architecture. Still further, this invention relates to optical articles and other molded articles made from the silicone copolycarbonates prepared according to the method of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily by reference to the following description of preferred embodiments of the invention and the Examples included herein.
It is to be understood that this invention is not limited to specific synthetic methods or to particular compositions falling within the class of silicone copolycarbonates. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings.
The singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that description includes instances where the event or circumstance occurs and instances where it does not.
“BPA” is herein defined as bisphenol A or 2,2-bis(4-hydroxy-phenyl)propane.
“BCC” is herein defined as 1,1-bis(4-hydroxy-3-methylphenyl) cyclohexane.
“BPI” is herein defined as 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
“BPZ” is herein defined as 1,1-bis-(4-hydroxyphenyl)cyclohexane.
“C
p
” represents the heat capacity of a material.
“Degree of oligomerization” as used herein refers to the value of r in structural formula IV.
“Identically constituted” as used herein refers to silicone copolycarbonates which have roughly the same molecular weight and which contain the same relative number of moles of repeat units I and II, said relative number of moles of repeat units I and II being determined by nuclear magnetic resonance spectroscopy (NMR). Two silicone copolycarbonates are defined herein as having roughly the same molecular weight when each exhibits an M
w
value which is within 10% of the M
w
value measured for the other composition by gel permeation chromatography (gpc) using polyst
Buttner David J.
Caruso Andrew J.
General Electric Company
Patnode Patrick K.
LandOfFree
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