Flame retardant polymer blends, and method for making

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...

Reexamination Certificate

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C524S566000, C524S537000, C524S141000, C524S137000

Reexamination Certificate

active

06174942

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to blends of thermoplastic polymers, and more particularly to flame retardant blends having improved high temperature properties.
Improvement of the flame retardant properties of thermoplastic polymers such as polycarbonates has long been a goal of polymer compounders. Compounds containing phosphorus have been used in compositions with thermoplastic polymers to improve their flame resistance properties. Among the phosphorus compounds useful for this purpose are the bis(diaryl phosphate) esters of dihydroxyaromatic compounds, as illustrated by resorcinol bis(diphenyl phosphate), hydroquinone bis(diphenyl phosphate), and bisphenol A bis(diphenyl phosphate). Certain water soluble phosphoramides have also been used in the textile industry as flame retardant finishes for fabrics.
Phosphorus-containing compounds, however, often have undesirable effects on other physical properties of thermoplastic polymers. For example, phosphorus-containing compounds frequently have undesirable effects on the high temperature properties of polycarbonate and polycarbonate-containing blends, especially those blends also containing addition polymers such as acrylonitrile-butadiene-styrene copolymers (hereinafter referred to as “ABS copolymers”). Said undesirable effects may be demonstrated by a pronounced decrease in glass transition temperature (Tg) of one or more polymer phases. In addition, other physical properties of the blends, such as ductility, are sometimes adversely affected and may require improvement.
There are increasing demands from key industries, such as the electronics and computer industries, for polymer compositions possessing both flame retardant properties and higher heat resistance. Such compositions must also retain other key physical properties, such as adequate flow and impact strength, for applications such as computer housings, computer monitor housings, and printer housings. Another increasing demand is for materials that are rated in the Underwriter's Laboratory UL-94 test protocol as V-0, V-1, or V-2. It is therefore apparent that new resin compositions that meet these and other demands continue to be sought.
SUMMARY OF THE INVENTION
The present invention meets that above-described needs by providing resin compositions comprising the following and any reaction products thereof:
a) at least one polycarbonate comprising structural units of the formula I
wherein each R
1
is independently H, C
1-3
alkyl, or halogen, each R
2
, R
3
, R
4
, and R
5
is independently C
1-6
alkyl, each R
6
and R
7
is independently H or C
1-6
alkyl, and n is 0-2;
b) at least one addition polymer; and
c) at least one phosphoryl compound of the formula II:
wherein Q is oxygen or sulfur; and R
8
, R
9
, and R
10
are each independently an alkyloxy, alkylthio, aryloxy, or arylthio residue, or an aryloxy or arylthio residue containing at least one alkyl or halogen substitution, or mixture thereof; or an amine residue.
The present invention also provides articles made from the resin compositions. Furthermore, the present invention provides methods to make resin compositions having improved heat and/or processability over compositions known in the art.
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment, the composition of the present invention comprises a polycarbonate resin comprising spirobiindane structural units of formula I:
wherein each R
1
is independently selected from monovalent hydrocarbon radicals and halogen radicals; each R
2
, R
3
, R
4
, and R
5
is independently C
1-6
alkyl; each R
6
and R
7
is independently H or C
1-6
alkyl; and each n is independently selected from positive integers having a value of from 0 to 3 inclusive. These polycarbonates containing spirobiindane structural units are derived from at least one dihydric phenol selected from spiro dihydric phenols represented by the formula III:
The monovalent hydrocarbon radicals represented by R
1
include alkyl radicals, cycloalkyl radicals, aryl radicals, aralkyl radicals, and alkaryl radicals. Alkyl radicals represented by R
1
are preferably those containing from 1 to about 12 carbon atoms, and include branched alkyl radicals and straight chain alkyl radicals. Some illustrative non-limiting examples of these alkyl radicals include methyl, ethyl, propyl, isopropyl, butyl, tertiary-butyl, pentyl, neopentyl, and hexyl. Cycloalkyl radicals represented by R
1
are preferably those containing from 3 to about 12 ring carbon atoms. Some illustrative non-limiting examples of these cycloalkyl radicals include cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl. Aryl radicals represented by R
1
are preferably those containing from 6 to 12 ring carbon atoms. Some illustrative non-limiting examples of these aryl radicals include phenyl, biphenyl, naphthyl. Preferred aralkyl and alkaryl radicals represented by R
1
are those containing from 7 to about 14 carbon atoms. These include, but are not limited to, benzyl, ethylphenyl, phenylbutyl, phenylpropyl, propylphenyl, and phenylethyl. The preferred halogen radicals represented by R
1
are fluorine, chlorine and bromine.
In the dihydric phenol compound of formula III when more than one R
1
substituent is present they may be the same or different. The relative positions of the hydroxyl groups and R
1
on the aromatic nuclear residues may be varied in the ortho or meta positions. The position of each hydroxy group is independently at any unsubstituted site on each of the aromatic rings. More preferably each hydroxy group is independently in positions 5 or 6 and 5′ or 6′ of each aromatic ring. Most preferably each hydroxy group is in position 6 and 6′ of each aromatic ring.
Preferably, each R
1
is independently selected from chlorine, bromine, and lower alkyl radicals containing from 1 to about 5 carbon atoms, each R
2
, R
3
, R
4
, and R
5
is independently C
1-6
alkyl; each R
6
and R
7
is independently H or C
1-6
alkyl; and each n is independently 0 to 3. More preferably, each R
1
is independently selected from chlorine and lower alkyl radicals containing from 1 to about 3 carbon atoms, each R
2
, R
3
, R
4
, and R
5
is independently C
1-2
alkyl; each R
6
and R
7
is independently H or C
1-2
alkyl; and each n is independently 0 to 2. Still more preferably, each R
2
, R
3
, R
4
, and R
5
is methyl; each R
6
and R
7
is H; and each n is 0.
Some illustrative non-limiting examples of suitable spiro dihydric phenols of formula III include:
The spiro dihydric phenols of formula III are compounds that are known in the art and are commercially available or may be readily prepared by known methods. Methods of preparation include those described in U. S. Pat. No. 4,701,566; and by R. F. Curtis and K. O. Lewis in Journal of the Chemical Society (England), 1962, p. 420; and by R. F. Curtis in Journal of the Chemical Society (England), 1962, p. 417. In one illustrative, non-limiting example these spiro dihydric phenols may be conveniently prepared by (i) reacting two moles of a phenolic compound with one mole of a carbonyl-containing compound such as acetone, and (ii) thereafter coreacting 3 moles of the product of (i) under acidic conditions to form the spiro dihydric phenol and 4 moles of a phenolic compound. The acids which may be utilized in (ii) can include such acids as anhydrous methane sulfonic acid, anhydrous hydrochloric acid, and the like.
The most preferred spiro dihydric phenol for forming polycarbonates suitable for use in the present invention is 6,6′-dihydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobiindane (“SBI”), in which n is 0 and the linkages with the rest of the polymer molecule are in a specific position on the aromatic rings. For the sake of brevity, said units will frequently be designated SBI units hereinafter. However, it should be understood that polycarbonates with structural units derived from other spiro dihydric phenols of formula III are also contemplated.
Both homopolycarbonates and copolycarbonates are suitable for use in composition

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