Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-09-12
1999-08-17
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
523106, C08F 800
Patent
active
059394897
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a novel process for the production of mouldings, in particular contact lenses, in which a crosslinkable polymer or a crosslinkable polymer mixture commprising crosslinkable groups, acidic groups and/or basic groups is crosslinked in solution, and to mouldings, in particular contact lenses, which are obtainable by this process.
The present invention also relates to novel crosslinkable polymers which can be employed in the crosslinking process, in particular those based on starting polymers containing functional groups, for example hydroxyl groups, on the polymer chain or functional groups, for example imino groups, in the polymer chain or functional groups bonded to the polymer skeleton via a bridge, where these functional groups allow covalent bonds to compounds containing a crosslinkable modifier group or another modifier group. These starting polymers are, in particular, polyhydroxyl compounds having a 1,2- and/or 1,3-diol structure, such as polyvinyl alcohol, or hydrolysed copolymers of vinyl acetate, for example copolymers with vinyl chloride, N-vinylpyrrolidone, etc. These are, in particular, crosslinkable polymers comprising units containing a crosslinkable group in addition to units containing an acidic group, crosslinkable polymers comprising units containing a crosslinkable group in addition to units containing a basic group, and novel crosslinkable polymers comprising units containing a crosslinkable group in addition to units containing an acidic group and units containing a basic group, and furthermore crosslinked polymers, either homopolymers or copolymers, made from these novel crosslinkable polymers, a process for the preparation of the novel crosslinkable polymers and the homopolymers and copolymers obtainable therefrom, mouldings made from said homopolymers or copolymers, in particular contact lenses made from these homopolymers or copolymers, and a process for the production of contact lenses using the said homopolymers or copolymers.
The novel crosslinkable polymers must, as mentioned, comprise units containing crosslinkable groups. The term crosslinkable groups is taken to mean conventional crosslinkable groups which are well-known to the person skilled in the art, for example photocrosslinkable or thermally crosslinkable groups. Particularly suitable crosslinkable groups are those as have already been proposed for the preparation of contact-lens materials. These include, not exclusively, in particular groups containing a carbon-carbon double bond. However, in order to demonstrate the variety of crosslinkable groups which are suitable, crosslinking mechanisms which may be mentioned here merely by way of example, are free-radical polymerization, 2+2 cycloaddition, Diels-Alder reaction, ROMP (ring opening metathesis polymerization), vulcanization, cationic crosslinking and epoxy curing.
In addition to the units containing a crosslinkable group, the novel crosslinkable polymers must also comprise a group which has an acid functionality or additionally must comprise a group which has a basic functionality.
However, it is also possible for the crosslinkable polymer to comprise all three units, so that all three groups are present, namely a crosslinkable group, an acidic group and a basic group. In this case, the polymers are intramolecular salts.
Preference is given to crosslinkable polymers comprising units containing a crosslinkable group and an acidic group and units containing a crosslinkable group and a basic group. In this case, a mixture of these two crosslinkable polymers is preferably crosslinked.
The present invention relates, in particular, to crosslinkable polymers in which the linking of these units to the starting polymer backbone takes place covalently, so that these groups are bonded irreversibly.
Suitable starting polymers here are all polymers based on polyhydroxyl compounds, in particular those having a 1,3-diol backbone, especially polyvinyl alcohol.
In a polyvinyl alcohol of this type, a certain percentage of the 1,3-diol units has, in accordance
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Lee Michael U.
Michl Paul R.
Novartis AG
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