CROSSLINKED ORGANIC POROUS PARTICLES
Crosslinked organic porous particles are non-swellable in propyl acetate and have a crosslinked organic solid phase and discrete pores dispersed within the crosslinked organic solid phase, which discrete pores are isolated from each other. The discrete pores have an average size greater than or equal to 0.1 μm and the crosslinked organic porous particles have a mode particle size of at least 3 μm and up to and including 100 μm. The discrete pores can contain a marker material.
1 . A crosslinked organic porous particle comprising a crosslinked organic polymer that provides a crosslinked organic solid phase including an external particle surface and discrete pores that are isolated from each other and dispersed within the crosslinked organic solid phase, the discrete pores having an average size greater than or equal to 0.1 μm, and the mode particle size of the crosslinked organic porous particles is at least 3 μm and up to and including 100 μm.
2 . The crosslinked organic porous particle of claim 1 wherein the crosslinked organic polymer is a chemically crosslinked thermoplastic resin.
3 . The crosslinked organic porous particle of claim 1 that is insoluble in propyl acetate for 24 hours at room temperature.
4 . The crosslinked organic porous particle of claim 1 further comprising a radiation absorber in one or more of the discrete pores.
5 . The crosslinked organic porous particle of claim 1 having a porosity of at least 1% and up to and including 80% of total crosslinked organic porous particle volume.
6 . The crosslinked organic porous particle of claim 1 that recovers at least 80% of its volume after being subjected to 200° C. and 1500 pounds (105.5 kg f /cm 2 ) pressure for 5 minutes.
7 . The crosslinked organic porous particle of claim 1 comprising first discrete pores comprising a first marker material, and second discrete pores that are either empty of marker materials or comprise a second marker material, which first and second marker materials are detectably different.
8 . The crosslinked organic porous particle of claim 7 wherein the first and second marker materials are selected from the group consisting of different colored pigments or dyes, different fluorescing materials, different radioisotopes, particles of different metal or metal-containing compounds having different magnetic moments, different luminescing compounds, and different bioactive materials.
9 . The crosslinked organic porous particle of claim 7 further comprising additional discrete pores besides the first and second discrete pores that optionally have a marker material different from the first and second marker materials.
10 . The crosslinked organic porous particle of claim 1 wherein at least some of the pores comprise a pore stabilizing hydrocolloid that is selected from the group consisting of carboxymethyl cellulose (CMC), a gelatin or gelatin derivative, a protein or protein derivative, a hydrophilic synthetic polymer, a water-soluble microgel, a polystyrene sulfonate, poly(2-acrylamido-2-methylpropanesulfonate), and a polyphosphate.
11 . The crosslinked organic porous particle of claim 1 wherein the pores have an average size of at least 0.1 μm and up to and including 4 μm.
12 . The crosslinked organic porous particle of claim 1 wherein the first and second discrete pores have different average sizes.
13 . The crosslinked organic porous particle of claim 1 that has a mode particle size of at least 5 μm and up to and including 70 μm.
14 . The crosslinked organic porous particle of claim 1 having an aspect ratio of at least 0.9.
15 . The crosslinked organic porous particle of claim 1 having an aspect ratio of at least 0.4 and up to but less than 0.95.
16 . The crosslinked organic porous particle of claim 1 wherein its external surface comprises small colloidal particles.
17 . The crosslinked organic porous particles of claim 1 wherein its external surface comprises small colloidal silica particles.
18 . A multiplicity of the crosslinked organic porous particles of claim 1 that is in either powder form, or an aqueous suspension.