Thermosetting resin compositions comprising cross-linked reactive microparticles with improved mechanical strength
The invention relates to thermosetting compositions, in particular coating or molding compositions, comprising crosslinked polymer microparticles with a size ranging from 10 to 300 nm and carrying at least one reactive functional group which can react with at least one of the reactive components of the thermosetting composition. Preferably, these microparticles carry at least one second reactive functional group distinct from the first which can react with at least one other functional group of the same type carried by another microparticle and/or by a reactive component of the thermosetting composition. These microparticles are at least partially soluble, miscible and/or dispersible in the starting thermosetting composition. The preferred thermosetting compositions are based on resins of epoxy/amine type or on unsaturated polyester resins and/or on vinyl ester resins. The coatings or molded items obtained exhibit very good mechanical, thermal and chemical strength resulting from the presence of these microparticles.
1. A thermosetting composition comprising crosslinked polymer microparticles with a size of between 10 and 200 nm, wherein the microparticles are at least partially soluble, miscible and/or dispersible in the starting thermosetting composition and carry at least one first reactive functional group which can react with at least one reactive functional group carried by at least one reactive component of the thermosetting composition
wherein the microparticles carry at least one functional group which reacts by a polycondensation reaction and at least one second functional group which is an α,β-ethylenic unsaturation which can polymerize by the radical route or by a specific Michael reaction and wherein the thermosetting composition comprises:
a) at least one unsaturated polyester and/or at least one unsaturated polyester modified by a poly-isocyanate and/or at least one vinyl ester,
b) at least one copolymerizable comonomer carrying at least one α,β-ethylenic unsaturation chosen from vinylaromatic and/or (meth)acrylic and/or allyl monomers,
c) optionally at least one second monomer carrying at least two reactive functional groups, one of which can polymerize by the radical route and the other by a condensation reaction,
d) 0.5-50% by weight of the said reactive crosslinked microparticles.
2. The composition as claimed in claim 1 , wherein said microparticlcs carry at least one (meth)acrylate or hydrogen maleate functional group.
3. The composition as claimed in claim 1 , wherein said microparticles can be obtained by a first polymerization stage starting from:
i) 10-40 mol % of Cardura E10 (meth)acrylate,
ii) 10-75 mol % of butyl and/or tert-butyl and/or 2-ethylhexyl and/or 2-(2-ethoxyethoxy)ethyl (meth)acrylate and of styrene, with a molar ratio of styrene to (meth)acrylic monomers varying from 0 to 0.2,
iii) 5-40 mol % of hydroxyethyl (meth)acrylate, maleic anhydride, (meth)acrylic acid or glycidyl methacrylate,
iv) 2-10 mol % of hexanediol and/or propylene glycol and/or neopentyl glycol and/or trimethylolpropane (meth)acrylate,
with the sum of the molar percentages of all these constituents i)+ii)+iii)+iv) being equal to 100, followed by a second stage of at least partial chemical modification of the starting reactive functional groups according to:
the starting hydroxyl functional groups to hydrogen maleates by reaction with maleic anhydride and/or to (meth)acrylates by reaction with (meth)acrylic acid,
the starting epoxy functional groups to (meth)acrylates by reaction with (meth)acrylic acid,
the acid functional groups to methacrylate by reaction with glycidyl methacrylate,
the anhydride functional groups to (meth)acrylates and residual acids by reaction with a hydroxyethyl or hydroxypropyl (meth) acrylate or with glycidyl methacrylate.
4. A coating comprising the composition of claim 1 .
5. The coating of claim 4 , wherein said coatings are protective coatings for electrical or electronic components, items or devices.
6. The thermosetting composition of claim 1 applied to molded items and of items made of composite materials.
7. A thermoset matrix obtained from the thermosetting composition of claim 1 .
8. A protective coating, molded item or item made of composite materials obtained from the thermosetting composition of claim 1 .