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| United States Patent | 4939185 |
| Link to this page | http://www.wikipatents.com/4939185.html |
| Inventor(s) | Nelson; Linda H. (Evansville, IN);
Avakian; Roger W. (Brasschaat, BE);
Factor; Arnold (Scotia, NY) |
| Abstract | Compounds having defined thioether groups are described which color
stabilize aromatic carbonate polymers or blends therewith upon exposure to
sterilizing radiation. |
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Title Information  |
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| Publication Date |
July 3, 1990 |
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| Filing Date |
August 18, 1989 |
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| Parent Case |
This is a continuation of application Ser. No. 07/136,604 filed 12/22/87,
now abandoned which was a division of application Ser. No. 06/769,277
filed 08/26/85 abandoned, which was a continuation in part of application
Ser. No. 06/579,103 filed 02/10/84 abandoned.
This invention relates to aromatic carbonate polymers and blends containing
carbonate polymers rendered resistant to yellowing by sterilizing
irradiation. More particularly, this invention relates to aromatic
carbonate polymers containing certain additives having functional groups
effective to color stabilize such polymers upon exposure to sterilizing
radiation.
BACKGROUND OF THE INVENTION
Aromatic carbonate polymers are well known thermoplastic materials which,
due to their many advantageous properties, find use as thermoplastic
engineering materials. The aromatic carbonate polymers exhibit, for
example, excellent properties of toughness, impact resistance, heat
resistance and dimensional stability. Not only are molded parts prepared
from aromatic carbonate polymers, but films and sheet materials as well.
Because of its excellent property spectrum, aromatic carbonate polymers
such as aromatic polycarbonate have been proposed for various utilities
including those relating to medical packaging, for example the containers
in which syringes, surgical instruments, intravenous fluids, operating
room devices, and the like are maintained. Additionally polycarbonate has
been used in medical devices such as blood oxygenators, anesthesia
canisters, intravenous connectors and accessories, blood centrifuge bowls,
surgical instruments and operating room instruments. The toughness of the
polycarbonate as well as its clarity, high heat resistance, strength and
good blood compatibility make it a potential substance of choice in this
high technology medical device and packaging market. Sterilization of
these articles used in the medical arts and other technologies is often
times required.
However, one particular difficulty with certain sterilization techniques
has been discovered. A typical method of sterilizing various objects
useful in medical practice is through irradiation. The type of radiation
usually employed is low level gramma or electron beam radiation. It is
readily apparent that the level of such radiation which accomplishes the
sterilization is significantly above that of ordinary background
radiation. When exposed to radiation which is of sufficient strength and
duration to sterilize various objects, the aromatic carbonate polymeric
material is subject to yellowing. This yellowing of the aromatic carbonate
reduces its clarity and alters its appearance and thereby reduces its
utility. Not only packaging materials such as flexible aromatic carbonate
film and sheet products but also molded parts as well suffer from this
yellowing phenomonon.
New additives have been discovered which inhibit the yellowing of aromatic
carbonate polymers after exposure to sterilization irradiation. Thus,
particularly in the medical and food industries, the utility of
polycarbonate film, sheet, and molded parts may be increased. |
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Title Information |
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Description |
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DESCRIPTION OF THE INVENTION
Briefly, according to the present invention, there are provided sterilizing
radiation color stabilized aromatic carbonate polymers which contain an
effective amount of a stabilizing compound effective to inhibit yellowing
upon sterilizing radiation exposure, the compound is selected from the
group consisting of organic acids (--COOH), esters (--COOR.sup.3),
alcohols (--OH), thiols, thioethers and cyclic thioethers, anilides
(--NHC.sub.6 H.sub.5), amines (--NH.sub.2), oxamides (NHCOCONH.sub.2),
diketones (>CO), sulfones (--SO.sub.2 --), alkenes (>C.dbd.C<),
hydroaromatics, and pyranyl compounds.
Aromatic carbonate polymer generally includes both the polycarbonates and
the copolyestercarbonates. The aromatic polycarbonate resins for use
herein can be prepared by reacting a dihydric phenol with a carbonate
precursor, such as phosgene, a haloformate or a carbonate ester. Generally
speaking, such carbonate polymers may be typified as possessing recurring
structural units of the formula:
##STR1##
wherein A is a divalent aromatic radical of the dihydric phenol employed
in the polymer producing reaction. Preferably, the carbonate polymers used
to provide the resinous mixtures of the invention have an intrinsic
viscosity (as measured in methylene chloride at 25.degree. C.) ranging
from about 0.30 to about 1.00 dl/g. The dihydric phenols which may be
employed to provide such aromatic carbonate polymers are mononuclear or
polynuclear aromatic compounds, containing as functional groups two
hydroxy radicals, each of which is attached directly to a carbon atom of
an aromatic nucleus. Typical dihydric phenols are:
2,2-bis(4-hydroxyphenyl)propane;
hydroquinone;
resorcinol;
2,2-bis-(4-hydroxyphenyl)pentane;
2,4'-dihydroxydiphenylmethane;
bis-(2-hydroxyphenyl)methane;
bis-(4-hydroxyphenyl)methane;
bis-(4-hydroxy-5-nitrophenyl)methane;
1,1-bis(4-hydroxyphenyl)ethane;
3,3-bis(4-hydroxyphenyl)pentane;
2,2-dihydroxydiphenyl;
2,6-dihydroxynaphthalene;
bis-(4-hydroxydiphenyl)sulfone;
bis-(3,5-diethyl-4-hydroxyphenyl)sulfone;
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)propane;
2,4'-dihydroxydiphenyl sulfone;
5'-chloro-2,4'-dihydroxydiphenyl sulfone;
bis-(4-hydroxyphenyl)diphenyl sulfone;
4,4'-dihydroxydiphenyl ether;
4,4'-dihydroxy-3,3'-dichlorodiphenyl ether;
4,4'-dihydroxy-2,5-dihydroxydiphenyl ether; and
the like.
Other dihydric phenols which are also suitable for use in the preparation
of the above polycarbonates are disclosed in U.S. Pat. Nos. 2,999,835;
3,028,365; 3,334,154; and 4,131,575.
These aromatic polycarbonates can be manufactured by known processes, such
as, for example and as mentioned above, by reacting a dihydric phenol with
a carbonate precursor, such as phosgene, in accordance with methods set
forth in the above-cited literature and U.S. Pat. Nos. 4,018,750 and
4,123,436, or by transesterification processes such as are disclosed in
U.S. Pat. No. 3,153,008, as well as other processes known to those skilled
in the art.
It is possible to employ two or more different dihydric phenols or a
copolymer of a dihydric phenol with a glycol or with a hydroxy or acid
terminated polyester or with a dibasic acid in the event a carbonate
copolymer or interpolymer rather than a homopolymer is desired for use in
the preparation of the polycarbonate mixtures of the invention. Branched
polycarbonates are also useful, such as are described in U.S. Pat. No.
4,001,184, also there can be utilized blends of a linear polycarbonate and
a branched polycarbonate. Moreover, blends of any of the above materials
may be employed in the practice of this invention to provide the aromatic
polycarbonate. In any event, the preferred aromatic carbonate polymer for
use as component (a) (i) herein is a homopolymer derived from
2,2-bis(4-hydroxyphenyl)propane (bisphenol-A).
The copolyestercarbonate usually employed may generally be described as
polymers comprising recurring carbonate groups,
##STR2##
carboxylate groups,
##STR3##
and aromatic carbocyclic groups in the linear polymer chain, in which at
least some of the carboxylate groups and at least some of the carbonate
groups are bonded directly to ring carbon atoms of the aromatic carboxylic
groups. These copolyestercarbonate copolymers in general, are prepared by
reacting a difunctional carboxylic acid or ester forming derivative, a
dihydric phenol and a carbonate precursor.
The dihydric phenols useful in formulating the copolyestercarbonates for
use herein may be represented by the general formula:
##STR4##
in which A is an aromatic group such as phenylene, biphenylene,
naphthylene, anthrylene, etc. E may be an alkylene or alkylidene group
such as methylene, ethylene, propylene, propylidene, isopropylidene,
butylene, butylidene, isobutylidene, amylene, isoamylene, amylidene,
isoamylidine and generally from one to twelve carbon atoms, inclusive,
etc. Where E is an alkylene or alkylidene group, it may also consist of
two or more alkylene or alkylidene groups, connected by a nonalkylene or
non-alkylidene group such as an aromatic linkage, a tertiary amino
linkage, an ether linkage, a carbonyl linkage, a silicon-containing
linkage, or by a sulfur-containing linkage such as sulfide, sulfoxide,
sulfone, etc. In addition, E may be a cycloaliphatic group of five to
seven carbon atoms, inclusive (e.g. cyclopentyl, cyclohexyl), or a
cycloalkylidene of five to seven carbon atoms inclusive, such as
cyclohexylidene, a sulfur containing linkage, such as sulfide, sulfoxide
or sulfone; an ether linkage; a carbonyl group; a tertiary nitrogen group,
or a silicon containing linkage such as silane or siloxy. Other groups
which E may represent will occur to those skilled in the art. R is
hydrogen or a monovalent hydrocarbon group such as alkyl of one to eight
carbon atoms, inclusive (methyl, ethyl, propyl, etc.), aryl (phenyl,
naphthyl, etc.), aralkyl (benzyl, ethylphenyl, etc.) or cycloaliphatic of
five to seven carbon atoms, inclusive (cyclopentyl, cyclohexyl, etc.). Y
may be an inorganic atom such as chlorine, bromine, fluorine, etc.; an
organic group such as the nitro group, etc.; an organic group such as R
above, or an oxy group such as OR, it being only necessary that Y be inert
to and unaffected by the reactants and the reaction conditions. The letter
m is any whole number from and including zero through the number of
positions on A available for substitution; p is any whole number from and
including zero through the number of available positions on E; t is a
whole number equal to at least one, S is either zero or one, and u is any
whole number including zero.
In the dihydric phenol compound represented by Formula II above, when more
than one Y substituent is present, they may be the same or different. The
same is true for the R substituent. Where s is zero in Formula II and u is
not zero, the aromatic rings are directly joined with no intervening
alkylene or other bridge. The positions of the hydroxyl groups and Y on
the aromatic nuclear residues A can be varied in the ortho, meta, or para
positions and the groupings can be in a vicinal, asymmetrical or
symmetrical relationship, where two or more ring carbon atoms of the
aromatic hydrocarbon residue are substituted with Y and hydroxyl group.
Examples of dihydric phenol compounds that may be employed in the
copolyestercarbonate include:
2,2-bis-(4-hydroxyphenyl)propane (bisphenol-A);
2,4'-dihydroxydiphenylmethane;
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-hydroxyphenyl)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-hydroxynaphthyl)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)cyclohexylmethane;
1,2-bis-(4-hydroxyphenyl)-1,2-bis-(phenyl)propane;
2,2-bis-(4-hydroxyphenyl)-1-phenylpropane; and the
like. Also included are dihydroxybenzenes typified by hydroquinone and
resorcinol, dihydroxydiphenyls such as 4,4'-dihydroxydiphenyl;
2,2'-dihydroxydiphenyl; 2,4'-dihydroxydiphenyl; dihydroxy-naphthalenes
such as 2,6-dihydroxynaphthalene, etc.
Also useful are dihydric phenols wherein E is a sulfur containing radical
such as the dihydroxy aryl sulfones exemplified by:
bis-(4-hydroxyphenyl)sulfone; 2,4'-dihydroxydiphenyl sulfone;
5-chloro-2,4'-dihydroxy diphenyl sulfone; 3-chloro-bis-(4-hydroxyphenyl)
sulfone; and 4,4'-dihydroxytriphenyldisulfone; etc. The preparation of
these and other useful sulfones are described in U.S. Pat. No. 2,288,282.
Polysulfones as well as substituted sulfones using halogen, nitrogen,
alkyl radicals, etc. are also useful.
Dihydroxy aromatic ethers such as those described in U.S. Pat. No.
3,148,172 are useful as the dihydric phenol herein. The dihydroxy aromatic
ethers may be prepared as described in U.S. Pat. No. 2,739,171.
Illustrative of such compounds are the following:
4,4'-dihydroxydiphenyl ether;
4,4'-dihydroxytriphenyl ether;
the 4,3'-, 4,2'-, 4,1'2,2'-, 2,3'-, etc. dihydroxydiphenyl ethers;
4,4'-dihydroxy-2,6-dimethyldiphenyl ether;
4,4'-dihydroxy-2,5-dimethyldiphenyl ether;
4,4'-dihydroxy-3,3'-diisobutyldiphenyl ether;
4,4'-dihydroxy-3,3'-diisopropylidiphenyl ether;
4,4'-dihydroxy-3,3'-dinitrodiphenyl ether;
4,4'-dihydroxy-3,3'-dichlorodiphenyl ether;
4,4'-dihydroxy-3,3'-difluorodiphenyl ether;
4,4'-dihydroxy-2,3'-dibromodiphenyl ether;
4,4'-dihydroxydinaphthyl ether;
4,4'-dihydroxy-3,3'-dichlorodinaphthyl ether;
2,4-dihydroxytetraphenyl ether;
4,4'-dihydroxypentaphenyl ether;
4,4'-dihydroxy-2,6-dimethoxydiphenyl ether;
4,4'-dihydroxy-2,5-diethoxy-diphenyl ether, etc.
Mixtures of the dihydric phenols can also be employed and where d | | |
