Polycarbonate-siloxane copolymers

Details Polycarbonate-siloxane copolymers Polycarbonate-siloxane copolymers

2001-10-09

2003-10-07

Buttner, David J. (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C525S067000, C525S147000, C528S025000, C528S029000, C528S204000

Reexamination Certificate

active

06630525

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention belongs to the field of polycarbonates. In particular, it relates to polycarbonate-siloxane copolymers.
Historically, flame retardance systems for polycarbonate utilize low levels of additives to provide flame poisoning and anti-drip behavior. The most commonly employed flame poisons are organic bromine compounds, organophosphates, and salts of sulfonic acids. Drip inhibition is effectively provided by poly(tetrafluoroethylene), PTFE. Unfortunately, organic bromine derivatives are prohibited as eco-label additives; organophosphates are unsuitable because at the levels required for their effectiveness, they plasticize polycarbonate reducing both continuous use temperature and impact strength to impractical levels; and PTFE is unsuitable due to its crystallinity and refractive index mismatch with polycarbonate that preclude its use in transparent products. Salts of sulfonic acids provide flame retardant properties to polycarbonate in thick samples (3.2 millimeters) for normal or low flow polycarbonate, but for high flow products, they are ineffective without drip inhibitors.
Due to the restraints of flame retardant additives, it would be advantageous to have a polycarbonate with a minimum amount of flame retardant additives that also maintains transparent properties. Thus, a need exists for polycarbonates having flame retardancy and high flow while maintaining transparency.
SUMMARY OF THE INVENTION
The present invention provides a polycarbonate comprising residues of;
(a) at least one dihydric phenol; and
(b) at least one comonomer comprising a siloxane functional bis-phenol of the formula
 wherein R is an alkyl group, cycloalkyl group, aryl group, fluoroalkyl group, or combinations thereof and n is in a range between 0 and 20;
(c) optionally, a branching agent; and
(d) optionally, a flame retardant.
The further embodiment of the present invention includes a method for producing a flame retardant polycarbonate comprising providing:
(a) at least one dihydric phenol; and
(b) at least one comonomer comprising a siloxane functional bis-phenol of the formula
 wherein R is an alkyl group, cycloalkyl group, aryl group, fluoroalkyl group, or combinations thereof and n is in a range between 0 and 20;
(c) optionally, a branching agent; and
(d) optionally, a flame retardant wherein the resulting polycarbonate is transparent.
DETAILED DESCRIPTION OF THE INVENTION
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 circumstances 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-hydroxyphenyl)propane.
Unless otherwise stated, “weight percent” in reference to the composition of a polycarbonate in this specification is based upon 100 weight percent of the repeating units of the polycarbonate. For instance, “a polycarbonate comprising 90 weight percent of BPA” refers to a polycarbonate in which 90 weight percent of the repeating units are residues derived from Bisphenol A or its corresponding derivative(s). Corresponding derivatives include, but are not limited to, corresponding oligomers of the diphenols; corresponding esters of the diphenol and their oligomers; and the corresponding chloroformates of the diphenol and their oligomers.
The present invention provides a polycarbonate comprising residues of;
(a) a dihydric phenol; and
(b) at least one comonomer comprising a siloxane functional bisphenol of the formula
 wherein R is an alkyl group, cycloalkyl group, aryl group, fluoroalkyl group, or combinations thereof and n is in a range between 0 and 20;
(c) optionally, a branching agent; and
(d) optionally, a flame retardant. Typically, R is a methyl group or a phenyl group
The utilization of the above monomers provides a useful combination of flame retardancy and high flow to the polycarbonate compositions as well as transparency. As used hereinafter, the term “flame retardant” means reduced or eliminated in tendency to ignite when exposed to a low-energy flame. As used hereinafter, the term “transparent” means a maximum percent haze of 15 and a minimum percent transmission of 75. As used hereinafter, “high flow” means a melt flow index no less than about 15 grams per 10 minutes at 300° C. and 1.2 kilograms.
The siloxane functional bisphenol is typically utilized in proportions in a range between about 1 mole percent and about 10 mole percent relative to the amount of the dihydric phenol, and more typically, in a range between about 1 mole percent and about 5 mole percent of the dihydric phenol. In this regard, the use of the term “residue” denotes that portion of the molecule or moiety which remains after the polycondensation reaction has taken place.
The dihydric phenol typically used in the present invention is 2,2-bis(4-hydroxyphenyl) propane (BPA). Optionally, the polycarbonate may be further comprised of other dihydric phenol compound residues in an amount up to about 10 to 50 weight percent of the repeating units in the polycarbonate, thereby replacing the Bisphenol A, of the present invention in the total amount of dihydric phenol compounds utilized. Examples of such compounds include the following:
resorcinol
4-bromoresorcinol
hydroquinone
4,4′-dihydroxybiphenyl ether
4,4-thiodiphenol
1,6-dihydroxynaphthalene
2,6-dihydroxynaphthalene
bis(4-hydroxyphenyl)methane
bis(4-hydroxyphenyl)diphenylmethane
bis(4-hydroxyphenyl)-1-naphthylmethane
1,1-bis(4-hydroxyphenyl)ethane
1,1-bis(4-hydroxyphenyl)propane
1,2-bis(4-hydroxyphenyl)ethane
1,1-bis(4-hydroxyphenyl)-1-phenylethane
1,1-bis(3-methyl-4-hydroxyphenyl)-1-phenylethane
2-(4-hydroxyphenyl)-2-)3-hydroxyphenyl)propane
2,2-bis(4-hydroxyphenyl)butane
1,1-bis(4-hydroxyphenyl)isobutane
1,1-bis(4-hydroxyphenyl)decane
1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane
1,1-bis(3,5-dibromo-4-hydroxyphenyl)cyclohexane
1,1-bis(4-hydroxyphenyl)cyclohexane
1,1-bis(4-hydroxyphenyl)cyclododecane
1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane
trans-2,3-bis(4-hydroxyphenyl)-2-butene
4,4-dihydroxy-3,3-dichlorodiphenyl ether
4,4-dihydroxy-2,5-dihydroxy diphenyl ether
2,2-bis(4-hydroxyphenyl)adamantane
&agr;,&agr;′-bis(4-hydroxyphenyl)toluene
bis(4-hydroxyphenyl)acetonitrile
2,2-bis(3-methyl-4-hydroxyphenyl)propane
2,2-bis(3-ethyl-4-hydroxyphenyl)propane
2,2-bis(3-n-propyl-4-hydroxyphenyl)propane
2,2-bis(3-isopropyl-4-hydroxyphenyl)propane
2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane
2,2-bis(3-t-butyl-4-hydroxyphenyl)propane
2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane
2,2-bis(3-allyl-4-hydroxyphenyl)propane
2,2-bis(3-methoxy-4-hydroxyphenyl)propane
2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane
2,2-bis(2,3,5,6-tetramethyl-4-hydroxyphenyl)propane
2,2-bis(3-5-dichloro-4-hydroxyphenyl)propane
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane
2,2-bis(2,6-dibromo-3,5-dimethyl-4-hydroxyphenyl)propane
&agr;,&agr;-bis(4-hydroxyphenyl)toluene
&agr;,&agr;,&agr;′,&agr;′-Tetramethyl-&agr;,&agr;′-bis(4-hydroxyphenyl)-p-xylene
1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene
1,1-dibromo-2,2-bis(4-hydroxyphenyl)ethylene
1,1-dichloro-2,2-bis(5-phenoxy-4-hydroxyphenyl)ethylene
4,4′-dihydroxybenzophenone
3,3-bis(4-hydroxyphenyl)-2-butanone
1,6-bis(4-hydroxyphenyl)-1,6-hexanedione
ethylene glycol bis(4-hydroxyphenyl)ether
bis(4-hydroxyphenyl)ether
bis(4-hydroxyphenyl)sulfide
bis(4-hydroxyphenyl)sulfoxide
bis(4-hydroxyphenyl)sulfone
bis(3,5-dimethyl-4-hydroxyphenyl)sulfone
9,9-bis(4-hydroxyphenyl)fluorene
2,7-dihydroxypyrene
6,6′-dihydroxy-3,3,3′,3′-tetramethylspiro(bis)indane(“spirobiindane Bisphenol”)
3,3-bis(4-hydroxyphenyl)phthalide
2,6-dihydroxydibenzo-p-dioxin
2,6-dihydroxythianthrene
2,7-dihydroxyphenoxathiin
2,7-dihydroxy-9,10-dimethylphenazine
3,6-dihyd

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