Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-09-10
2002-08-20
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S124600, C526S134000, C526S196000, C526S317100, C526S328500, C524S183000, C524S522000, C524S523000, C524S556000, C524S560000
Reexamination Certificate
active
06437065
ABSTRACT:
The present invention describes reactive systems which are composed of ethylenically unsaturated monomers on the one hand, and of oxygen-reactive organoboron compounds which are stabilized by means of carrier materials on the other hand. The monomer component additionally comprises small amounts of peroxides.
The novel reactive systems are suitable in principle for many applications, for example for the industrial or craft sector, but they have a particular and is preferred significance for use in medicine in human or animal tissue. They are suitable as binders or adhesives for bonding endogenous hard tissue and for bonding such tissue to synthetic material and/or metal and/or for in situ formation of synthetic material moldings in surgical work. They are used in particular in the area of reactive adhesive and cement systems for medical and/or dental applications and, in the last-mentioned area, also as filling materials.
Polymer-based synthetic materials, and reactive systems curable by initiation of reaction are becoming increasingly important both in human medicine and in the veterinary sector. Reference may be made to surgical and/or dental adhesives, cements, filling materials and the like which usually set after application and implantation into the living body and then remain in contact with the living body. The curable adhesives preferably employed in practice normally consist of the following components:
one or more free-radical polymerizable, ethylenically unsaturated monomers which are, where appropriate, mixed with inhibitors to prevent unwanted premature initiation of reaction;
a starter system to initiate polymerization;
polymers for improving cohesion and adjusting the viscosity and, where appropriate,
active fillers for improving the mechanical properties.
A starter system frequently used to initiate polymerization in reaction systems comprising ethylenic double bonds consists of oxygen-reactive organoboron compounds. There is a wide-ranging literature on this, and therefore the following publications may be cited as only a small selection: DE 30 41 843, DE 30 41 904, DE 31 43 945, DE 32 01 780, DE 32 04 504 or else DE 32 29 635.
DE 39 39 164 likewise describes starter systems based on oxygen-active organoboron compounds which are combined with a carrier material. The carriers employed are oligoesters of lower hydroxy carboxylic acids. These carriers improve the stability of the system towards oxygen. In order for such reactive boron compounds such as, for example, 9-borabicyclo[3.3.1]nonane (9-BBN) in fact to be processible and stable on storage, they are introduced into a matrix of an ester of a polyhydric alcohol, and of an oligomer of a hydroxy carboxylic acid.
However, even these systems are not optimal because it has been found that the storage stability is inversely proportional to the concentration of the boron compound. It would therefore be desirable to have starter systems or reactive systems in which the concentration of organoboron compounds was as low as possible, also because of the toxicity of the boron compounds, but without this reduction having a deleterious effect on the polymerization.
The object was therefore to find improved reactive or adhesive systems which have a content of organoboron compounds which is as low as possible, and wherein the criteria such as pot life, time to reach the final strength, and strength of the bonding, are likewise optimized.
It has now been found that the required results can be achieved by admixing a peroxide to the monomer component in the reaction system. Peroxides suitable for this purpose are in principle various structural elements, namely both peresters, hydroperoxides, perethers and peranhydrides. This is very surprising since it was absolutely unexpected that such monomer/peroxide mixtures can be manipulated and are stable on storage since it is often difficult even to store the monomer components stably on their own, i.e. to prevent unwanted polymerization.
The invention therefore relates to a two-component reactive system for polymerizing ethylenically unsaturated compounds, comprising as first component monomers capable of the polymerization(=reactive component), and as second component a starter or hardener system composed of organoboron compounds(=initiator component), which are stabilized with suitable oligomers, where these components are mixed for the application, characterized in that an organic peroxide is admixed to the monomers.
The invention further relates to the use of the reactive systems improved according to the invention in the area of joining hard body materials where appropriate together with synthetic material and/or metal in human or animal tissue, in particular also in the area of reactive adhesive or cement systems in the surgical and/or dental sector.
In this case, the peroxide is introduced into, that is to say suspended or dissolved in, the monomer components to be polymerized. The organic peroxides preferably used are those which dissolve in the monomer system.
The peroxide is thus in intimate contact with the reactive end groups of the substances to be polymerized, whereby the complete course of the polymerization is speeded up. The initiation of the polymerization thus takes place on the one hand by the action of the starter on the ethylenically unsaturated compounds, and on the other hand additionally due to the peroxide which is likewise induced to decompose by the starter and acts as polymerization accelerator.
However, a great advantage also derives from the fact that addition of the peroxide to the monomer allows the content of organoboron compound in the initiator component to be reduced, which is important in respect of toxicology.
It is possible in principle to use for this purpose all organic peroxides, that is to say peresters, hydroperoxides, perethers and peranhydrides. However, the selection is also determined by their distribution in the substances to be polymerized, a solution being preferred to suspensions. In addition, the peroxides or reaction catalysts which can be admixed must not be prone to decomposition at room temperatures or below 50° C. The peroxides preferably used have a half-life at 80° C. in the range from hours to days.
Particularly preferred peroxides have proved to be tert-butyl peroxybenzoate or di-tert-butyl peroxide.
The peroxides are admixed in an amount of from 0.005 to 10% by weight, preferably from 0.1 to 5% by weight, based on the monomer components.
The hardener or starter component employed in the reactive systems according to the invention are boron compounds having alkyl and/or aryl radicals, or bicyclic organoboron compounds, which are stabilized or retarded with suitable oligomers. Such a stabilization can preferably take place by the appropriate organic boron compounds being in the form of mixtures with oligomers or of adducts with unsaturated fats or oligomers resulting from a hydroboration reaction. These starter systems are well known to the skilled person and are, for example, described in detail in the documents DE 39 39 164, DE 32 07 263 or DE 32 07 264. This will therefore be dealt with only briefly below.
Thus, a preferred way of stabilizing the organoboron compounds is to prepare physical mixtures of these compounds with oligomers. One possibility for retardation is to mix the organic boron compounds homogeneously with an organic oligomer or polymer which is liquid or solid at room temperature and, where possible, compatible with the body. Suitable oligomeric or polymeric organic components in this case are preferably oligoesters, oligoamides and/or oligoethers which are liquids or spreadable pastes at room temperature.
A particularly preferred starter system consists of oxygen-reactive organoboron compounds in combination with a carrier material which is in the form of an oligoester of lower hydroxy carboxylic acids.
The essential ester-forming constituent of these carrier materials are thus hydroxy carboxylic acids of the preferred C number range from about 2 to 10.
Particularly importan
Pokinskyj Peter
Ritter Wolfgang
Wenz Robert
Merck Patent Gesellschaft mit beschrankter Haftung
Millen White Zelano & Branigan P.C.
Wu David W.
Zalukaeva Tatyana
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