Crosslinked polymers containing urethane groups

Details Crosslinked polymers containing urethane groups Crosslinked polymers containing urethane groups

1997-09-12

1998-09-15

Lipman, Bernard

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

525 59, 525 60, 525 61, C08F 814

Patent

active

058079270

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a novel process for the production of mouldings, in particular contact lenses, in which a novel crosslinkable polymer comprising units containing a crosslinkable group and at least one further modifier is crosslinked in solution, and to mouldings, in particular contact lenses, which are obtainable by this process.
The present invention also relates to novel polymers based on polyvinyl alcohol which contain cyclic acetal or ketal groups, and to novel crosslinkable polymers which can be employed in the novel 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.
The invention furthermore relates to crosslinked polymers, either homopolymers or copolymers, made from these novel crosslinkable polymers which contain a crosslinkable group and at least one further modifier, to a process for the preparation of these novel crosslinkable polymers and the homopolymers and copolymers obtainable therefrom, to mouldings made from said homopolymers or copolymers, in particular contact lenses made from these homopolymers or copolymers, and to a process for the production of contact lenses using the said homopolymers or copolymers.
Contact lenses based on polyvinyl alcohol have already been disclosed. For example, EP 216 074 discloses contact lenses comprising polyvinyl alcohol containing (meth)acryloyl groups bonded via urethane groups. EP 189 375 describes contact lenses comprising polyvinyl alcohol crosslinked by means of polyepoxides.
Furthermore, some specific acetals containing crosslinkable groups have also already been disclosed. In this connection, we refer, for example, to EP 201 693, EP 215 245 and EP 211 432. EP 201 693 describes, inter alia, acetals of unbranched aldehydes having 2 to 11 carbon atoms carrying a terminal amino group which is substituted by a C.sub.3 -C.sub.24 olefinically unsaturated organic radical. This organic radical contains a functionality which withdraws electrons from the nitrogen atom, and furthermore the olefinically unsaturated functionality is polymerizable. EP 201 693 also claims products of the reaction of the acetals characterized above with a 1,2-diol, a 1,3-diol, a polyvinyl alcohol or a cellulose. However, such products are not described directly.
If one of the acetals of EP 201 693 is mentioned at all in connection with, for example, polyvinyl alcohol, as is the case, inter alia, in Example 17 of that patent application, the acetal which can be polymerized via its olefinic group is first copolymerized with, for example, vinyl acetate. The resultant copolymer is then reacted with polyvinyl alcohol, and an emulsion having a solids content of 37%, a pH of 5.43 and a viscosity of 11,640 cps is obtained.
However, these references do not reveal the novel combination of a crosslinkable urethane structure with a second modifier having an acetal or urethane structure.
By contrast, the present invention relates, inter alia, in particular to polymers having, inter alia, a 1,2- and/or 1,3-diol skeleton, in which a certain percentage of the 1,3-diol units has been modified to give a 1,3-dioxane and to give a urethane group, or in which a certain percentage of the 1,3-diol units has been modified to give two different urethane groups, where at least one group bonded via urethane contains a crosslinkable radical. The crosslinkable radical is, in particular, an acrylate or vinyl ether radical. The present invention likewise relates to crosslinked homopolymers and copolymers of said c

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