Spray dried polyolefin elastomer powder for rotational molding processes
The present invention provides a method comprising rotational molding a powdered polyolefin elastomer composition to form a skin, the composition formed by spray drying an aqueous polyolefin dispersion composition which is itself formed by melt blending a polyolefin composition comprising an olefin block copolymer, a dispersing agent, and water, wherein said aqueous dispersion preferably has a pH less than 12.
1. A process for making a rotational molded skin comprising the steps of:
(i) forming an aqueous polyolefin dispersion by melt blending
(A) a polyolefin composition comprising an olefin block copolymer in the presence of
(B) at least one dispersing agent
and
(C) water,
(ii) spray drying said dispersion forming a powdered polyolefin composition having an average particle size equal to or less than 350 microns,
and
(iii) rotational molding said powdered polyolefin composition into a skin wherein the skin has a first surface and a second surface.
2. The process of claim 1 wherein (A) the polyolefin composition comprising the olefin block copolymer further comprises one or more of a random olefin copolymer, a polyethylene, a propylene, ethylene, α-olefin, a non-conjugated dienes based copolymers, an ethylene-vinyl acetate, an ethylene-vinyl alcohol, a chlorinated polyethylene, an alcohol functionalized polyolefin, an amine functional polyolefin, or a silane grafted polyolefin.
3. The process of claim 1 wherein (B) the dispersing agent is ethylene acrylic acid (EAA), ethylene-methacrylic acid (EMA), ethylene ethyl acrylate (EEA) copolymer, ethylene methyl methacrylate (EMMA), or ethylene butyl acrylate (EBA).
4. The process of claim 1 wherein (B) the dispersing agent is a long chain fatty acid having from 12 to 60 carbon atoms or a fatty acid salt having from 12 to 60 carbon atoms.
5. The process of claim 1 wherein the aqueous polyolefin dispersion is derived from the melt blending of (A) the olefin block copolymer, in the presence of (B) the dispersing agent which is a long chain fatty acid having from 12 to 60 carbon atoms or a fatty acid salt having from 12 to 60 carbon atoms, and (C) water.
6. The process of claim 1 wherein the polyolefin composition comprises one or more of a dye, a pigment, an organic filler, an inorganic filler, a plasticizer, a stabilizer, a surfactant, an anti-static agent, a tackifier, an oil extender, a crosslinking agent, a chemical blowing agent, an anti-microbial agent, a thickening agent, or an age resister.
7. The process of claim 1 further comprising the step of (v) applying a paint or lacquer layer to the first surface of the rotational molded skin.
8. The process of claim 1 further comprising the step of (iv) providing a foam backing to the second surface of the rotational molded skin.
9. The process of claim 1 further comprising the step of (iv) applying a paint or lacquer layer to the first surface of the skin and the step of (v) providing a foam backing to the second surface of the rotational molded skin.
10. The process of claim 1 wherein the aqueous polyolefin dispersion is blended with an aqueous colorant.
11. The process as claimed in claim 1 , wherein in the (i) forming the aqueous polyolefin dispersion by melt blending, the (A) polyolefin composition comprising the olefin block copolymer is an ethylene multi-block interpolymer having an ethylene content from 25 to 97 percent by weight.