Plastic molding materials which can be detected by X-ray...

Details Plastic molding materials which can be detected by X-ray... Plastic molding materials which can be detected by X-ray...

2001-06-01

2003-01-21

Niland, Patrick D. (Department: 1714)

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

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S165000, C524S341000, C524S463000, C523S117000, C424S009411, C424S009450, C424S009451

Reexamination Certificate

active

06509406

ABSTRACT:

The invention provides X-ray contrastable plastics materials with low-molecular weight iodine compounds, a process for preparing X-ray contrastable moulding compositions with low molecular weight iodine compounds, the use of low molecular weight iodine compounds to improve the X-ray contrast in transparent plastics materials and toys with improved X-ray contrast containing low molecular weight iodine compounds.
Materials with the highest possible transparency and good mechanical characteristics which can be detected in the body by using X-rays are sought for the medical field and also for children's toys. In contrast to metallic items, toys made of plastics are generally not detectable on an X-ray image. These types of moulding compositions can be made X-ray contrastable by means of suitable additives.
These types of moulding compositions were described, for example, in DE-A 195 45 289. In that patent, X-ray contrastable thermoplastic moulding compositions made of ABS with a BaSO
4
additive were described.
X-ray detectable moulding compositions were also described in Silberman-Hazony, Encycl. Polym. Sci. Eng. (1988), 14, 1-8. Thermoplastic materials with various heavy metals as X-ray contrast agents were described. In addition, a halogen-containing terpolymer was mentioned.
Finally, FR 2223403 describes PVC and other vinyl polymers with iodine-containing salicylic acids, benzoic acids and their esters which resemble those in U.S. Pat. Nos. 3,361,700 and 3,645,955. However, PVC is not suitable for applications in which high transparency and good mechanical properties are required.
DE-A 197 26 191 and the patents U.S. Pat. No. 3,469,704 and DE-A 17 20 812 cited therein described transparent plastics moulding compositions made of polycarbonates with iodine-containing terminal groups. However, these can, under some circumstances, involve considerable additional synthesis costs because the polymer chains themselves have to be modified.
Finally, U.S. Pat. No. 3,382,207 discloses iodine-containing diphenyl carbonates as additives for polycarbonates.
Thus, the prior art does not currently provide any adequate X-ray contrastable plastics materials for use in transparent plastics parts. Due to its outstanding mechanical properties, polycarbonate has hitherto been used in particular for transparent toy parts which are subject to high mechanical stress. Now, it is intended to develop a type of plastics material that can be detected within the context of a conventional X-ray photograph while having unchanged high transparency and the smallest possible impairment to its mechanical properties. The thickness of layer in which the plastics material is still detectable should be as small as possible, but at most 1.2 mm.
The object was to develop moulding compositions using readily obtainable additives in standard thermoplastic materials which exhibit adequate contrast in X-ray images while also having good mechanical characteristics and transparency. The addition of heavy metals was to be avoided for toxicological reasons since materials for children's toys were being sought.
Accordingly, the present application provides X-ray contrastable plastics materials containing at least one low molecular weight iodine compound, characterised in that the odine compound is present in amounts of 0.1 wt. % to 25 wt. % and is chosen from the lasses D-thyroxin, L-thyroxin, metrizamide, N,N′-bis-(2,3-dihydroxypropyl)-5-[N-(2,3-dihydroxypropyl)-acetamido]-3,4,6-triiodoisophthalamide, &agr;-(2,4,6-triiodophenoxy)-butyric acid, beta-bromo-2,4,6-triiodophenetols, ethylene glycol-4-(iodophenyl)-methylether-methylether and aromatic compounds in accordance with the following general formulae (I), (II), (III)
wherein R, R′, R″, R′″=COOH, OH, NHCOR″″, CONHR″″, OR″″, Cl, Br, F, R″″, where R″″ may be H or a linear or branched alkyl group with 1-18 carbon atoms. Furthermore, l=0 to 5, m=0 to 5−l, n=0 to 3, o=0 to 3−n p=0 to 4, q=0 to 4−p, r=0 to 4, s=0 to 4−r, t=0 to 5, u=0 to 5−t.
To prepare metrizamide see J. Cell. Biol. 1991, 113, 45, to prepare Iohexol® (N,N′-bis-(2,3-dihydroxypropyl)-5-[N-(2,3-dihydroxypropyl)-acetamido]-3,4,6-triiodoisophthalamide) see Sigma-Aldrich Chemie GmbH, Steinheim, Germany, to prepare Baygnostil® (&agr;-(2,4,6-triodophenoxy)butyric acid) see Bayer AG, Leverkusen, Germany.
Mixtures of all the iodine-containing compounds mentioned above are also suitable.
The following are particularly suitable: 4,4′-diiodobiphenyl, 2,3,5-triiodobenzoic acid, 2,4,6-triiodophenol, 4-iodophenol, 3-iodophenol, 2-iodophenol, 3,5-diiodosalicylic acid, 3,5-diiodo-2-hydroxybenzoic acid, 4-iodobenzoic acid, 3-iodobenzoic acid, 2-iodobenzoic acid, 2,6-dimethyl-4-iodophenol, 2-iodo-4-phenylphenol, 3,3′-diiodo-2,2′,6,6′-tetramethyl-4,4′-biphenol, 2,6-diiodo-4-methylphenol, 3,5-diiodo-2-hydroxybenzoic acid, 2,4-dichloro-6-iodophenol, 1,4-dimethoxy-2,3-dimethyl-5-iodobenzene, 1,2-dimethoxy-4-iodobenzene, 2,2′-diiodo-4,4′,5,5′-tetramethoxybiphenyl, 4-iodo-3-phenylanisol, 1,2-dimethoxy-3,4-dimethyl-5-iodobenzene, 2,2′-diodo-3,3′-dimethyl-4,4′,5,5′-tetramethoxybiphenyl, 1,4-dimethoxy-2-iodo-5-methylbenzene, 1,2-dimethoxy-4-iodo-5-methylbenzene, 1,2-diiodo-4,5-dimethoxybenzene, 2,2′-diiodo-3,3′,4,4′,5,5′-hexamethoxybiphenyl, 2,2′-diiodo-4,4′-dimethoxy-3,3′,5,5′-tetramethylbiphenyl, very particularly 4,4′-diiodobiphenyl.
The X-ray contrastable plastics materials contain the low molecular weight iodine compound in amounts between 0.5 and 20 wt. %, preferably between 0.8 and 10 wt. % and particularly preferably between 1 and 5 wt. %.
Transparent thermoplastic materials are preferably used as transparent plastics, 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, polyacrylates or copolyacrylates and polymethacrylates or copolymethacrylates such as e.g. polymethylmethacrylate or copolymethylmethacrylate, or else copolymers with styrene such as e.g. transparent polystyrene/acrylonitrile (SAN), also transparent cycloolefins, polycondensates or copolycondensates of terephthalic acid, such as e.g. polyethylene terephthalate or copolyethylene terephthalate (PET or COPET) or glycol-modified PET.
A person skilled in the art produces exceptional results with polycarbonates or copolycarbonates.
Thermoplastic, aromatic polycarbonates in the context of the present invention are either homopolycarbonates or copolycarbonates; the polycarbonates may be linear or branched in a known manner.
These polycarbonates are prepared in a known manner from diphenols, carbonic acid derivatives, optional chain stoppers and optional branching agents.
Details of the preparation of polycarbonates have been presented in many patent documents over the last 40 years. By way of example, reference is made here only to Schnell, “Chemistry and Physics of Polycarbonates”, Polymer Reviews, volume 9, Interscience Publishers, New York, London, Sydney, 1964, to D. Freitag, U. Grigo, P. R. Müller, H. Nouvertné, BAYER AG, “Polycarbonates” in Encyclopedia of Polymer Science and Engineering, volume 11, 2nd edition, 1988, pages 648-718 and finally to Drs. U. Grigo, K. Kirchner and P. R. Müller “Polycarbonate” in Becker/Braun, Kunststoff-Handbuch, vol. 3/1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag, Munich, Vienna 1992, pages 117-299.
Suitable diphenols for preparing 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,

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