초록 ▼

This invention relates to a water-swellable material comprising water-swellable polymers that are coated with a coating agent that comprises a phase-separating elastomeric material, which allows swelling of the water-swellable polymers, without breakage of the coating. The invention also relates to

This invention relates to a water-swellable material comprising water-swellable polymers that are coated with a coating agent that comprises a phase-separating elastomeric material, which allows swelling of the water-swellable polymers, without breakage of the coating. The invention also relates to a process of making specific coated water-swellable polymers using a phase-separating elastomeric material, and materials obtainable by such a process.

대표청구항 ▼

What is claimed is: 1. A water-swellable material, comprising water-swellable polymers that are coated with a coating agent, which comprises an elastomeric material that is phase-separating, having at least a first phase with a first glass transition temperature Tg1 and a second phase with a second

What is claimed is: 1. A water-swellable material, comprising water-swellable polymers that are coated with a coating agent, which comprises an elastomeric material that is phase-separating, having at least a first phase with a first glass transition temperature Tg1 and a second phase with a second glass transition temperature Tg2, and wherein said elastomeric material is a block copolymeric material, having a molecular weight of at least 50 kDa and wherein said block copolymeric material further comprises at least one block copolymer selected from the group consisting of polyurethane-co-polyethers, polyurethane-co-polyesters, polyurethane/urea-co-polyethers, polyurethane/urea-co-polyesters, polystyrene block copolymers and blends thereof. 2. A water swellable material according to claim 1 wherein the difference between Tg1 and Tg2 is at least 30째 C. 3. A process for making a water-swellable material that comprises coated water-swellable polymer particles, said process comprising the steps of: a) obtaining water-swellable polymer particles; b) applying a coating agent, wherein said coating agent of step b) comprises an elastomeric phase-separating material that has at least a first phase with a first glass transition temperature Tg1 and a second phase with a second glass transition temperature Tg 2, to at least a part of said water-swellable polymer particles and wherein said elastomeric material is a block copolymeric material, having a molecular weight of at least 50 kDa and wherein said block copolymeric material further comprises at least one block copolymer selected from the group consisting of polyurethane-co-polyethers, polyurethane-co-polyesters, polyurethane/urea-co-polyethers, polyurethane/urea-co-polyesters, polystyrene block copolymers and blends thereof.; and optionally the step of c) annealing the resulting coated water-swellable polymer particles of step b), so as to obtain said water-swellable material. 4. A process according to claim 3 wherein the coating agent is applied subsequent to step (a). 5. A process according to claim 3 wherein said coating agent is wet-extensible and has a wet-elongation at break of at least 400% and a tensile stress at break in the wet state of at least 1 MPa. 6. A process according to claim 3, wherein the coating agent has, in the wet state, a wet secant elastic modulus at 400% (SM wet400%) elongation of at least 0.5 MPa. 7. A process according to claim 4, wherein the coating agent has, in the dry state, a dry secant modulus at 400% elongation (SM dry400%) and a wet secant modulus at 400% elongation (SM wet400%), wherein the ratio of SMwet400% to SMdry400% is between 1.4:1.0 to 0.6:1.0. 8. A process according to claim 3, wherein said coating agent has a Moisture Vapour Transmission Rate (MVTR) of at least 800 g/m 2/day. 9. A water-swellable material comprising coated water-swellable polymer particles produced according to the process of claim 3. 10. A process according to claim 3 wherein said elastomeric phase-separating material has a Tg1 of less than 20째 C. and a Tg2 of more than 50째 C. 11. A process according to claim 3 wherein at least a portion of said water-swellable polymer particle are individually coated by the coating agent in the form of a continuous shell around, said shell having an average caliper of 1 μm to 50 μm. 12. A water-swellable material of claim 1 wherein said shell is substantially uniform with a ratio of smallest to largest caliper from 1:1 to 1:3.