Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-06-13
2002-02-19
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
Reexamination Certificate
active
06348560
ABSTRACT:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS
The present patent application claims the right of priority under 35 U.S.C. 119 and 35 U.S.C. 365 of International Application No. PCT/EP99/09557, filed Dec. 7, 1999, which was published in German as International Patent Publication No. WO 00/37530 on Jun. 29, 2000, which is entitled to the right of priority of German Patent Application No. 198 58 774.0, filed Dec. 18, 1998.
FIELD OF THE INVENTION
This invention relates to the use of oligocarbonates having terminal groups containing iodine for moulded articles having high X-ray contrast, in particular for toys and medical accessories.
BACKGROUND OF THE INVENTION
Materials which have as high a transparency as possible and good mechanical properties and can be detected in the body in X-ray examinations are sought for the field of medicine and for children's toys. Unlike metallic articles, as a rule articles made of plastic are not, or only with difficulty, detectable in the X-ray image, particularly behind bones. X-ray contrast can be imparted to such moulding compositions by means of suitable additives.
Transparent plastics moulding compositions made from polycarbonates having terminal groups containing iodine are described in U.S. Pat. No. 3,469,704 and DE-A 17 20 812.
However, the expense of synthesis, especially in the case of polymers having a high molecular weight, can be extremely high and the iodine content attained in the moulding is in some cases low.
In commercially available iodine-containing compounds, problems can arise in connection with the compatibility, the colour fastness and the migration of molecules.
In prior art there is thus to date still no plastics composition available having an adequate X-ray contrast for use as transparent plastics articles, particularly toys and medical accessories.
Owing to its excellent mechanical properties, polycarbonate has long been used in particular for parts of toys which are transparent and subjected to high mechanical stress. It is now intended to develop a type of plastic which can be detected in a conventional X-ray image, with unaltered high transparency and as far as possible only slightly impaired mechanical properties. The layer thickness at which the plastic is still detectable should be as small as possible, but at most 1.2 mm.
SUMMARY OF THE INVENTION
The object was to develop moulding compositions which possess an adequate contrast in X-ray examinations, while having good mechanical properties and transparency. The addition of heavy metals was excluded on toxicological grounds, as materials for children's toys were being sought.
The present application accordingly provides the use of oligocarbonates having terminal groups containing iodine for moulded articles having high X-ray contrast, wherein the oligocarbonates contain more than one diol unit and have a weight average molecular weight Mw of less than 3,000.
DETAILED DESCRIPTION OF THE INVENTION
Mixtures of the iodine-containing compounds specified above with one another and with other iodine-containing substances are possible.
Particularly suitable oligocarbonates are those containing iodinated phenols, such as 2-iodophenol, 3-iodophenol, 4-iodophenol, 2,3-diiodophenol, 2,4-diiodophenol, 2,5-diiodophenol, 2,6-diiodophenol, 3,4-diiodophenol, 3,5-diiodophenol, 2,3,4-triiodophenol, 2,3,5-triiodophenol, 2,3,6-triiodophenol, 2,4,5-triiodophenol, 2,4,6-triiodophenol, 3,4,5-triiodophenol, as well as their alkyl-substituted compounds, as terminal groups. 2,4,6-triiodophenol is a particularly preferred terminal group. All diols mentioned in the present patent for use in polycarbonate are suitable as a diol unit for the iodinated oligocarbonates; 2,2-bis(4-hydroxyphenyl)propane is preferred.
The moulded articles, in particular toys and medical equipment, contain the oligomeric iodine compound in quantities such that the iodine content is from 0.2 to 19.9 wt. %, preferably 0.3 to 15 wt. %, particularly preferably 0.4 to 10 wt. %.
The oligocarbonates having terminal groups containing iodine are generally used in transparent plastics.
The transparent plastics used are preferably transparent thermoplastics, particularly preferably the polymers of ethylenically unsaturated monomers and/or polycondensates of bifunctional reactive compounds.
Particularly suitable plastics are polycarbonates or copolycarbonates based on diphenols. The oligomers according to the invention may also be used, however, with poly- or copolyacrylates and poly- or copolymethacrylates such as, for example, poly- or copolymethyl methacrylate, and also as copolymers with styrene such as, for example, transparent polystyrene-acrylonitrile (SAN).
They may also be incorporated into transparent cycloolefins, poly- or copolycondensates of terephthalic acid such as, for example, poly- or copolyethylene terephthalate (PET or CoPET) or glycol-modified PET (PETG).
The person skilled in the art will achieve excellent results with polycarbonates or copolycarbonates.
Thermoplastic aromatic polycarbonates for the purpose of the present invention are either homopolycarbonates or copolycarbonates; the polycarbonates may, in known manner, be linear or branched.
The oligocarbonates and polycarbonates or copolycarbonates are produced in known manner from diphenols, carbonic acid derivatives, optionally chain stoppers and optionally branching agents.
Details regarding the production of polycarbonates have been set down in many patent specifications for about 40 years. Here reference is made, by way of example, only to Schnell, “Chemistry and Physics of Polycarbonates”, Polymer Reviews, Vol. 9, Interscience Publishers, New York, London, Sydney, 1964, to D. Freitag, U. Grigo, P. R. Müller, H. Nouvertne', BAYER AG, “Polycarbonates” in Encyclopedia of Polymer Science and Engineering, Vol. 11, Second Edition, 1988, pages 648-718 and finally, to Dres. U. Grigo, K. Kirchner and P. R. Müller, “Polycarbonates” in Becker/Braun, Kunststoff-Handbuch, Volume 3/1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag, Munich, Vienna, 1992, pages 117-299.
Suitable diphenols for the production of polycarbonates are, for example, hydroquinone, resorcinol, dihydroxydiphenyls, bis(hydroxyphenyl)alkanes, bis(hydroxyphenyl)cycloalkanes, bis(hydroxyphenyl) sulfides, bis(hydroxyphenyl) ethers, bis(hydroxyphenyl) ketones, bis(hydroxyphenyl) sulfones, bis(hydroxyphenyl) sulfoxides, &agr;,&agr;′-bis(hydroxyphenyl)diisopropylbenzenes, as well as their ring-alkylated and ring-halogenated compounds.
Preferred diphenols are 4,4′-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 1,1 -bis(4-hydroxyphenyl)-p-diisopropyl-benzene, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3-chloro-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)methane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)sulfone, 2,4-bis(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1 -bis(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)-propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
Particularly preferred diphenols are 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 1,1 -bis(4-hydroxyphenyl)cyclohexane and 1,1 -bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
These and other suitable diphenols are described for example in U.S. Pat. Nos. 3,028,635, 2,999,835, 3,148,172, 2,991,273, 3,271,367, 4,982,014 and 2,999,846, in Deutsche Offenlegungsschriften 1 570 703, 2 063 050, 2 036 052, 2 211 956 and 3 832 396, in the French Patent 1 561 518, in the monograph by H. Schnell, “Chemistry and Physics of Polycarbonates”, Interscience Publishers, New York, 1964 and in the Japanese published patent applications 62039/1986, 62040/1986 and 105550/1986.
In the case of homopolycarbonates, only one diphenol is used. In the case of copolycarbonates, seve
Brenner Axel
Döbler Martin
Köhler Walter
Neumann Siegfried
Bayer Aktiengesellschaft
Boykin Terressa M.
Franks James R.
Gil Joseph C.
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