Polycarbonate-polysiloxane block copolymers

Details Polycarbonate-polysiloxane block copolymers Polycarbonate-polysiloxane block copolymers

2000-06-01

2003-12-02

Wu, David W. (Department: 1713)

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S104000, C525S09200D, C528S026000, C528S029000, C528S162000, C524S164000, C524S588000

Reexamination Certificate

active

06657018

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to thermoplastic condensation polymers which are polycarbonate-polysiloxane block copolymers with enhanced properties such as solvent resistance, low temperature impact strength, improved processing and flame retardance, useful as thermoplastic molding resins.
2. Brief Description of Related Art
Aromatic carbonate polymers have found wide use as engineering thermoplastics, having inherent toughness and clarity. However, these polymers have generally had deficiencies such as inadequate solvent resistance, showing a tendency to craze or crack when exposed to many common solvents. Low temperature impact strength of carbonate polymers has also been considered to be in need of improvement. At low temperatures, brittle fractures are often a problem. Many variants of carbonate polymers have been tried in attempts to overcome these deficiencies.
Copolymers having polysiloxane and polycarbonate blocks are known. Representative of such polymers are those disclosed by Vaughn, U.S. Pat. Nos. 3,189,662 (June 1965) and 3,419,635 (December 1968).
The known polycarbonate-polysiloxane copolymers, while useful, also have several deficiencies. First, the polymers disclosed by Vaughn in U.S. Pat. No. 3,189,662 have aryloxysilicon structures which are hydrolytically unstable., as would be deduced from the publication dealing with this structure, by Rosenberg et al., J. Polymer Science, Polymer Chemistry Edition, 1982, 29, 1ff. Vaughn in U.S. Pat. No. 3,419,635 remedies this shortcoming by teaching the use of the more stable C-Si linkages in place of the aryloxysilicon linkages in organopolysiloxane-polycarbonate copolymers. Vaughn teaches that his polymers are useful in elastomeric applications, suitable for flexible windows, roofing, adhesives, denture bases, and other applications where non-elastomeric thermoplastics are not ordinarily used. In fact, Vaughn teaches the use of vulcanization to process his polymers in a rubber-like manner.
We have now found that within the broad range of polysiloxane-polycarbonate block copolymers taught by Vaughn, there is a class of compositions, in regard to the mode of attachment of the silicon to the phenolic ring, and with regard to the silicone loading and silicone block length, which possess advantageous physical and chemical properties, including improved processing properties, improved low temperature properties and improved solvent resistance, such that these copolymers are highly useful as thermoplastic molding resins.
SUMMARY OF THE INVENTION
The invention comprises polysiloxane-polycarbonate block copolymers with advantageous thermoplastic molding resin properties consisting essentially of: (1) polycarbonate blocks having recurring units of the formula:
where R
3
and R
4
are each independently selected from hydrogen, hydrocarbyl or halogen-substituted hydrocarbyl, preferably. methyl; and (2) polysiloxane blocks of the structure:
where R
1
and R
2
are each independently hydrogen, hydrocarbyl or halogen-substituted hydrocarbyl (preferably R
1
is methyl and R
2
is methyl or phenyl) and where D is an integer of from about 10 to about 120, preferably about 40-60; and Y is hydrogen, hydrocarbyl, hydrocarbyloxy or halogen, (preferably methoxy); and p
1
where the weight percentage of blocks of structure (1) is from about 96 to about 92.0% of the copolymers and the weight percentage of siloxane from the blocks of structure (2) is from about 4 to 8%.
As illustrated in Table 1, the weight percentage of siloxane from the blocks of structure (
2
) is from about 4 to 8%.
The term “hydrocarbyl” as used herein means the monovalent moiety obtained upon removal of a hydrogen atom from a parent hydrocarbon. Representative of hydrocarbyl are alkyl of 1 to 25 carbon atoms, inclusive such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, undecyl, decyl, dodecyl, octadecyl, nonodecyl eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl and the isomeric forms thereof; aryl of 6 to 25 carbon atoms, inclusive, such as phenyl, tolyl, xylyl, napthyl, biphenyl, tetraphenyl and the like; aralkyl of 7 to 25 carbon atoms, inclusive, such as benzyl, phenethyl, phenpropyl, phenbutyl, phenhexyl, napthoctyl and the like; cycloalkyl of 3 to 8 carbon atoms, inclusive, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like.
The term “alkylene” means the divalent moiety obtained on removal of two hydrogen atoms, each from a non-adjacent carbon atom of a parent hydrocarbon and includes alkylene of 3 to 15 carbon atoms, inclusive, such as 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,8-octylene, 1,10-decylene and the like.
The term “halogen-substituted hydrocarbyl” as used herein means the hydrocarbyl moiety as previously defined wherein one or more hydrogen atoms have been replaced with halogen (chlorine, bromine, iodine, fluorine).
DETAILED DESCRIPTION OF THE INVENTION
The block copolymers of the invention are prepared by the reaction of a carbonate forming precursor, such as phosgene, with a bisphenol of the formula:
where R
3
and R
4
are as defined above; and a siloxane diol of the structure depicted by the formula:
where R
1
and R
2
Y and D are as defined above. A particularly preferred species of Formula (IV) is that in which R
1
and R
2
are methyl, Y is methoxy ortho to the phenolic hydroxyl, and D is about 45-55.
The bisphenol compounds of the formula (III) are represented by 2,2-bis-(4-hydroxyphenyl)propane (or bisphenol-A);
2,4′-dihydroxydiphenyl methane;
bis-(2-hydroxyphenyl) methane;
bis-(4-hydroxyphenyl) methane;
bis-(4-hydroxy-5-nitrophenyl) methane;
bis-(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)-methane;
1,1-bis-(4-hydroxyphenyl) ethane;
1,2-bis-(4-hydroxphenyl) ethane;
1,1-bis-(4-hydroxy-2-chlorophenyl) ethane;
1,1-bis-(2,5-dimethyl-4-hydroxyphenyl) ethane;
1,3-bis-(3-methyl-4-hydroxyphenyl) propane;
2,2-bis-(3-phenyl-4-hydroxyphenyl) propane;
2,2-bis-(3-isopropyl-4-hydroxyphenyl) propane;
2,2-bis-(4-hydroxyphenyl) propane;
2,2-bis-(4-hydroxyphenyl) pentane;
3,3-bis-(4-hydroxyphenyl) pentane;
2,2-bis-(4-hydroxyphenyl) heptane;
bis-(4-hydroxyphenyl) phenylmethane;
bis-(4-hydroxyphenyl) cyclohexymethane;
1,2-bis-(4-hydroxyphenyl)-1,2-bis-(phenyl) propane;
2,2-bis-(4-hydroxyphenyl)-1-phenylpropane; and the like.
The siloxane diols (IV) depicted above as precursors of the siloxane block may be characterized as bisphenolsiloxanes. The preparation of these bisphenolsiloxanes is accomplished by the addition of a polydiorganosiloxane (V) to a phenol (VI) containing an alkenyl substituent, according to the schematic formula:
wherein R
1
, R
2
, Y and D are as defined above.
The essential features of the process are described by Vaughn, U.S. Pat. No. 3,419,635 (December 1968), which is incorporated by reference. For instance, the process is exemplified in example 8 of this Vaughn patent which describes the addition of a hydrogen-terminated polydimethylsiloxane to an allylphenol in the presence of a catalytic amount of chloroplatinic acid-alcohol complex at 90-115° C.
Particularly preferred polysiloxane blocks (a) are made from bisphenolpolysiloxanes (IV) where R
1
and R
2
are methyl and where Y is methoxy located ortho to the phenolic substituent. These are readily prepared by addition of a hydrogen-terminated polysiloxane to two molar equivalents of eugenol (4-allyl-2-methoxyphenol) in a reaction advantageously catalyzed by platinum or its compounds.
The hydrogen-terminated polysiloxanes of formula (V) are well-known compositions, being described along with methods for their preparation, in Vaughn U.S. Pat. Nos. 3,419,634 and 3,419,635.
The allylphenols of formula VI are also well known compounds, described along with methods for their preparation, by Tarbell, Chemical Reviews 27, 495ff (1940).
A particularly preferred compound of Formula (VI) is eugenol, 4-allyl-2-nethoxyphenol, since it is readily available as a synthetic or as a natural product and affords a bisphenolpolysiloxane (IV) of favorable reactivity.
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