CA1115880A - Plasticized polycarbonate composition - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A plasticized polycarbonate composition comprising in admixture a high molecular weight aromatic carbonate polymer and a minor amount of a cyclic siloxane plasticizer.
The resulting compositions have reduced melt viscosities and are useful in the fabrication of molded articles.

Description

~ 8CH-2592 This invention is directed to a plasticized poly-carbonate composition comprising in admixture a high molecular weight aromatic carbonate polymer and a minor amount of a particular cyclic siloxane plasticizer.
Polycarbonate polymers are excellent molding materials as products made therefrom have high impact strength, tough-ness, high transparency, wide temperature limits (high impact resistance below -60C and a UL thermal endurance rating of 115C with impact), good dimensional stability, high creep resistance and electrical properties which qualify it as sole support for current carrying parts.
Polycarbonates are, however, very difficult to fabricate from melts for the reason that melts thereof have exceptionally high viscosities. Attempts to overcome this difficulty by the incorporation with the polycarbonate of materials known to reduce the viscosity of other resins have very generally been unsuccessful. Many standard viscosity control agents appear to have little or no effect on the viscosity of polycarbonate. Other compounds known to lower the viscosity of resins cause degradation of polycarbonate resins. Some compounds, conventionally employed to improve the work-ability of polymers, produce an embrittling effect on polycarbonates when they are mixed therewith and the resin is subjected to elevated temperatures as in molding. Still other materials, while satisfactory stiffness modifying agents for other plastics, are too volatile to be incorporated with polycarbonates since polycarbonates have much higher melting points than many other thermoplastics.
From U.S. Patent No. 3,751,519 dated August 7, 1973 it is known that certain phenyl substituted cyclosiloxane and alkyl substituted phenyl substituted cyclosiloxanes when added to aromatic polycarbonates provide a composition ~ ~.

which has mold release properties.
It has been surprisingly discovered that, by admixing a minor amount of a particular organic plasticizer with a high molecular weight aromatic carbonate polymer, the resultant polycarbonate composition has reduced melt viscosity and does not become brittle or degraded upon molding and thus retains its characteristic high impact strength.
In the practice of this invention, the cyclic siloxane plasticizer additive is characterized by the following formula:
R R

Si \ R
si / si/
R ~ O ~O R
Si /)0-7 R / \ R
wherein R is independently selected from the group consisting of Cl to C36 alkyl, C1 to C36 alkoxy, aryloxy of 6 to 14 carbon atoms, aralkoxy of 7 to 36 carbon atoms, halogen substituted aryl of 6 to 14 carbon atoms and C5 to C30 alkyl substituted aryl of 6 to 14 carbon atoms, wherein the substituted aryl is bonded to said silicon atom through an intervening oxygen atom.
These cyclic siloxane plasticizers are prepared by methods known in the art. For example, these plasticizers are prepared by the hydrolysis of the halogen precursor or by isomerization or disproportionation of the linear polymers.
These methods are set forth in Walter Noll, Chemis*ery and Technology of Silicones, Academic Press, 1969.
The amount of organic plasticizer employed in the practice of this invention may vary from 0.50 to about 5.0 parts per hundred parts of aromatic carbonate polymer.
Preferably, these organic plasticizers are employed in ~ ~1 S ~ ~ 8CH-2592 amounts of from 0.25 to 2.0 parts per hundred parts of aromatic carbonate polymer.
In the practice of this invention, the high molecular weight aromatic polycarbonates that can be employed herein are homopolymers and copolymers and mixtures thereof which have an I.V. of 0.40 to 1.0 dl./g. as measured in methylene chloride at 25C that are prepared by reacting a dihydric phenol with a carbonate precursor. Typical of some of the dihydric phenols that may be employed in the practice of this invention are bisphenol-A, (2,2-bis(4-hydroxyphenyl) propane), bis (4-hydroxyphenyl) methane, 2,2-bis(4-hydroxy-3-methylphenyl) propane, 4,4-bis(4-hydroxyphenyl) heptane,

2,2-(3,5,3', 5'-tetrachloro-4,4'-dihydroxydiphenyl) propane, 2,2-(3,5,3'-tetrabromo-4,4'-dihydroxydiphenyl) propane, (3,3'-dichloro-4,4'-dihydroxydiphenyl) methane. Other dihydric phenols of the bisphenol type are also available and are disclosed in U.S. Patents 2,999,835 dated September 12, 1961, 3,028,365 dated April 3, 1962 and 3,334,154 dated August 1, 1967.
It is, of course, possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with a dibasic acid in the event a carbonate copolymer or inter-polymer rather that a homopolymer is desired for use in the preparation of the aromatic car-bonate polymers of this invention. Also employed in the practice of the invention may be blends of any of the above materials to provide the aromatic carbonate polymer.
The carbonate precursor may be either a carbonyl halide, a carbonate ester or a haloformate. The carbonyl halides which can be employed herein are carbonyl bromide, carbonyl chloride and mixtures thereof. Typical of the 1~8~ 8CH-2592 carbonates esters which may be employed herein are diphenyl carbonate, di-(halophenyl) carbonates such as di-(chlorophenyl) carbonate, di-(bromophenyl) carbonate, di-(trichlorophenyl) carbonate, di-(tribromophenyl) carbonate, etc., di-(alkyl-phenyl) carbonates such as di(tolyl) carbonate, etc., di-(napthyl) carbonate, di-(chloronaphthyl) carbonate, phenyl tolyl carbonate, chlorophenyl chloronaphthyl carbonate, etc., or mixtures thereof. The haloformates suitable for use herein include bis-haloformates of dihydric phenols (bischlorofor-mates of hydroquinone, etc.) or glycols (bishaloformates of ethylene glycol, neopentyl glycol, polyethylene glycol, etc.).
While other carbonate precursors will occurs to those skilled in the art, carbonyl chloride, also known as phosgene, is preferred.
Also included are the polymeric derivatives of a dihydric phenol, a dicarboxylic acid and carbonic acid. These are disclosed in U.S. Patent 3,169,121 dated February 9, 1965.
The aromatic carbonate polymers of this invention may be prepared by employing a molecular weight regulator, an acid acceptor and a catalyst. The molecular weight re-gulators which can be employed in carrying out the process of this invention include monohydric phenols such as phenol, chroman-I, paratertiarybutylphenol, parabromophenol, primary and secondary amines, etc. Preferably, phenol is employed as the molecular weight regulator.
A suitable acid acceptor may be either an organic or an inorganic acid acceptor. A suitable organic acid acceptor is a tertiary amine and includes such materials as pyridine, triethylamine, dimethylaniline, tributylamine, etc. The inorganic acid acceptor may be one which can be either a hydroxide, a carbonate, a bicarbonate, or a phosphate of an alkali or alkaline earth metal.
The catalysts which are employed herein can be any of 1~15~8~ 8CH-2592 the suitable catalysts that aid the polymerization of bis-phenol-A with phosgene. Suitable catalysts include tertiary amines such as, for example, triethylamine, tripropylamine, N,N- dimethylaniline, quaternary ammonium compounds such as, for example, tetraethylammonium bromide, cetyl triethyl ammonium bromide, tetra-n-heptylammonium iodide, tetra-n-propyl ammonium bromide, tetra-methylammonium chloride, tetramethyl ammonium hydroxide, tetra-n-butyl ammonium iodide, benzyltrimethyl ammonium chloride and quaternary phosphonium compounds such as, for example, n-butyltriphenyl phosphonium bromide and methyltriphenyl phosphonium bromide.
Also, included herein are branched polycarbonates wherein a polyfunctional aromatic compound is reacted with the dihydric phenol and carbonate precursor to provide a thermoplastic randomly branched polycarbonate.
These polyfunctional aromatic compounds contain at least three functional groups which are carboxyl, carboxylic anhydride, haloformyl or mixtures thereof. Examples of these polyfunctional aromatic compounds which may be employed in the practice of this invention include: trimellitic anhydride, trimellitic acid, trimellityl trichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid, pyro-mellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetetracarboxylic acid, benzo-phenonetetracarboxylic anhydride and the like. The prefer-red polyfunctional aromatic compounds are trimellitic anyhdride or trimellitic acid or their haloformyl derivatives.
Also, included herein are blends of a linear poly-carbonate and a branched polycarbonate.
The composition of the instant invention is prepared by blending the high molecular weight aromatic polycarbonate with the additive by conventional methods.

l~lS~3 ~CH~2592 Obviously, other materials can also be employed with the aromatic carbonate polymer of this invention and in-clude such materials as anti-static agents, pigments, thermal stabilizers, ultraviolet stabilizers, reinforcing fillers and the like.
In order to more fully and clearly illustrate the present invention, the following specific examples are presented. It is intended that the examples be considered as illustrative rather than limiting the invention disclosed and claimed herein. In the examples, all parts and per-centages are on a weight basis unless otherwise specified.
One hundred (100) parts of an aromatic polycarbonate, prepared from 2,2-bis(4-hydroxyphenyl) propane and phosgene in the presence of an acid acceptor and a molecular weight regulator and having an intrinsic viscosity of about 0.57, is mixed with the additive listed in the Table by tumbling the ingredients together in a laboratory tumbler. The resulting mixture is then fed to an extruder which is operated at about 265C, and the extrudate is comminuted into pellets.
2Q The pellets are then fed into a plastometer and the flow rate of polymer is measured according to ASTM D1238-70, Condition O. The melt flow rate is set forth in the Table.
Additionally, the pellets are injection molded at about 315C into test specimens of about 5 by 1/2 by 1/8 inch thick. The impact strength of these specimens is then measured according to the Izod test, ASTM D256. The impact strength is set forth in the Table. The sample labeled CONTROL is the polycarbonate as prepared without additive.

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~15~0 It can be seen from the data in the Table that when the instant organic plasticizer is added to a high molecular weight aromatic polycarbonate, the resulting polycarbonate composition has reduce melt viscosity as shown by the higher melt flow rate while retaining impact strength.
It will thus be seen that the objects set forth above among those made apparent from the preceding description are efficiently attained and since certain changes may be made in carrying out the above process and in the composition set forth without departing from the scope of this invention, it is intended that all matters contained in the above des-cription shall be interpreted as illustrative and not in a limiting sense.

Claims (6)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A plasticized polycarbonate composition comprising in admixture a high molecular weight aromatic carbonate polymer and a minor amount of a cyclic siloxane plasticizer of the following formula:

wherein R is independently selected from the group consisting of C1 to C36 alkyl, aryloxy of 6 to 14 carbon atoms, aralkoxy of 7 to 36 carbon atoms, halogen substituted aryl of 6 to 14 carbon atoms and C5 to C30 alkyl substituted aryl of 6 to 14 carbon atoms, wherein said alkyl substituted aryl is bonded to said silicon atom through an intervening oxygen atom.

2. The composition of claim 1 wherein the organic plasticizer is present in an amount of from 0.05 to about 5.0 parts per hundred parts of aromatic carbonate polymer.

3. The composition of claim 1 wherein the aromatic carbonate polymer is derived from bisphenol-A.

4. The composition of claim 1 wherein the aromatic carbonate polymer is a copolymer derived from bisphenol-A and tetrabromo bisphenol-A.

5. The composition of claim 1 wherein the organic plasticizer has the following formula:

,

6. The composition of claim 1 wherein the organic plasticizer has the following formula:

,