US-12624167-B2 - Curable compositions containing thiol compounds

Abstract

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.

Inventors

• Xinyu Zhou
• Mingxin Fan

Assignees

• ARKEMA FRANCE

Dates

Publication Date

20260512

Application Date

20171031

Claims (18)

1. 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. 2 . The photocurable composition of claim 1 further comprising d) other additives different from a) to c).
3. 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. 4 . The photocurable composition of claim 1 , wherein the composition further comprises at least one (meth)acrylate-functional oligomer.
5. 5 . The photocurable composition of claim 1 , wherein said polythiol has a functionality in the secondary thiol group from 2 to 6.
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. 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. 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. 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. 10 . The photocurable composition of claim 1 , wherein said urethane oligomer according to a) has at least two allylic groups.
11. 11 . The photocurable composition of claim 1 , wherein said urethane oligomer according to a) bears alkoxy units.
12. 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. 13 . The photocurable composition of claim 1 , wherein the composition is curable by UV, LED, or visible light.
14. 14 . A coating, ink, adhesive or varnish comprising at least one composition as defined according to claim 1 .
15. 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. 16 . Finished cured product resulting from curing the composition as defined according to claim 1 .
17. 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. 18 . The photocurable composition of claim 1 , wherein the composition further comprises at least one monomer bearing at least one allyl-functional group.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. national stage application under 35 U.S.C. § 371 of international application number PCT/CN2017/108523, filed Oct. 31, 2017. FIELD OF THE INVENTION The present invention relates to stable compositions of thiol-ene based UV curable polymer used in coatings, adhesives and inks. The composition exhibits good shelf stability, fast curing speed, less susceptible to oxygen inhibition with resulting cured films which exhibit excellent optical clarity, low shrinkage, flexibility, adhesion to a variety of substrates. They are especially suitable for optical and electronic applications, in particular optical lenses, optical adhesives or films or opto-electronic devices and sensors. BACKGROUND OF INVENTION The crosslinking of unsaturated polymers through the addition of elemental sulfur was discovered in 1839 by Goodyear. It is used extensively in the tire industry to this day. The application of the thiol-ene reaction are also far ranging, in both polymer and synthetic chemistry. Initiation occurs by radical formation upon UV excitation of a photoinitiator or the thiol itself. The resulting sulfenyl radical subsequently adds to the unsaturated alkene to form a new carbon radical. A reaction of thiol and a carbon-carbon double bond is known as a thiol-ene reaction. Typical ultraviolet radiation curable (meth)acrylate materials are known to experience oxygen inhibition when cured. The oxygen inhibition is limited to the surface of the materials. For ultra-thin coating and LED cured ink, the oxygen inhibition becomes a bulk problem as opposed to a surface issue. So the results about cured products exhibit insufficient adhesion to a substrate or insufficient hardness. As is well known, shrinkage can cause unpredictable defect in precise molding operations such as those required in manufacture of optical elements such as BEF (Brightness Enhancement Films). Shrinkage can also create residual stress in such optical film, which can subsequently lead to optical defects including high birefringence. SUMMARY OF THE INVENTION The present invention relates to a photopolymerizable 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, andc) at least one photoinitiator. The composition can be made free of solvent and can be rapidly photocured. When cured, the composition exhibits low shrinkage and excellent optical and electronic performances. It is suitable for many optical applications such as optical lenses, optical adhesive and optical film. BRIEF DESCRIPTION The present invention relates to a thiol-ene photocurable composition that is used in UV cured system with excellent flexibility, low shrinkage, adhesion, less susceptible to oxygen inhibition and hardness. A first subject of the invention relates to 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, andc) at least one photoinitiator. A second subject of the invention relates to the use of said photocurable composition in coatings, inks, adhesives and varnishes. Another subject of the present invention relates to a finished product resulting from the cure of at least one photocurable composition according to the present invention. Finally the invention does also cover the use of said finished product for optical or electronic or optoelectronic applications. DETAILED DESCRIPTION The first subject of the invention relates to a photocurable thiol-ene composition which comprises: 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 bearing at least two of said functional groups one of which is an allyl group, b) at least one polythiol bearing at least one secondary thiol group and c) at least one photoinitiator. The photocurable composition may further comprise d) other additives different from a) to c). Examples of suitable additives d) are pigments, polymer impact modifiers, liquid crystal materials, metal powders, wetting agents, slipping agents. More particularly said photocurable composition comprises: 10 to 80 wt % of said at least one monomer or/and oligomer a): 2 to 50 wt %, preferably from 10 to 50 wt % and more preferably from 10 to 30 wt % of