Curable compositions containing thiol compounds
Provided is a photocurable composition comprising: a) at least one monomer or/and oligomer bearing at least one functional group selected from the group consisting of (meth) acrylate-functional group, vinyl-functional and allyl-functional group or at least one monomer or/and oligomer bearing at least two of said functional groups with one of them being an allyl group, b) at least one polythiol bearing at least one secondary thiol group, and c) at least one photoinitiator. The said composition can be used in coatings, inks, adhesives and varnishes. A finished cured product made of the said composition is suitable for optical, electronic and opto-electronic applications.
1 . A photocurable thiol-ene composition comprising:
a) 10 to 80 wt % of at least one aliphatic or cycloaliphatic urethane oligomer bearing at least one allyl-functional group or at least one aliphatic or cycloaliphatic urethane oligomer bearing at least two functional groups selected from the group consisting of (meth)acrylate-functional group, vinyl-functional group and allyl-functional group with one of said at least two functional groups being an allyl group,
b) 10 to 50 wt % of at least one polythiol bearing at least one secondary thiol group,
c) at least one photoinitiator, and
e) at least one reactive diluent selected from the group consisting of monofunctional or multifunctional (meth)acrylates, wherein said reactive diluent is copolymerizable with.
2 . The photocurable composition of claim 1 further comprising d) other additives different from a) to c).
3 . The photocurable composition of claim 2 , comprising:
c) 0.1 to 10 wt % of said at least one photo-initiator c),
and wherein the composition further comprises
d) 0.1 to 50 wt % of said other additives,
with the sum of a)+b)+c)+d)+e) being 100%.
4 . The photocurable composition of claim 1 , wherein the composition further comprises at least one (meth)acrylate-functional oligomer.
5 . The photocurable composition of claim 1 , wherein said polythiol has a functionality in the secondary thiol group from 2 to 6.
6 . The photocurable composition of claim 1 , wherein said polythiol b) is selected from Pentaerythritol tetrakis (3-mercaptobutyrate) as shown in the formula (I) below:
7 . The photocurable composition of claim 1 , wherein said urethane oligomer bears at least one (meth)acrylate group and at least one allyl group.
8 . The photocurable composition claim 4 , wherein said (meth)acrylate-functional oligomer is a (meth)acrylated non-hydrogenated polydiene polyol oligomer, bearing internal cis/trans ethylenic unsaturation.
9 . The photocurable composition of claim 8 , wherein said (meth)acrylated polydiene polyol oligomer is selected from the group consisting of (meth)acrylated polyols of: polybutadiene, polyisoprene and random or block copolymers of butadiene or of isoprene with a comonomer.
10 . The photocurable composition of claim 1 , wherein said urethane oligomer according to a) has at least two allylic groups.
11 . The photocurable composition of claim 1 , wherein said urethane oligomer according to a) bears alkoxy units.
12 . The photocurable composition of claim 1 , further comprising f) 0.05 to 2% w/w with respect to the sum of a)+b)+c)+d)+e) of at least one stabilizer which is a free radical scavenger selected from hindered substituted phenolic or hindered substituted amine compounds.
13 . The photocurable composition of claim 1 , wherein the composition is curable by UV, LED, or visible light.
14 . A coating, ink, adhesive or varnish comprising at least one composition as defined according to claim 1 .
15 . The coating, ink, adhesive or varnish of claim 14 , for use in optical applications selected from optical lenses, optical adhesives and optical films.
16 . Finished cured product resulting from curing the composition as defined according to claim 1 .
17 . The photocurable composition of claim 8 , wherein said (meth)acrylated non-hydrogenated polydiene polyol oligomer comprises a (meth)acrylated non-hydrogenated polydiene diol oligomer.
18 . The photocurable composition of claim 1 , wherein the composition further comprises at least one monomer bearing at least one allyl-functional group.