1. Field of the Invention
The present invention relates multilayer thermoplastic resin pellets including a core and a sheath layer and to methods for producing the same.
Particularly, the invention relates to multilayer pellets excellent in fluidity, dispersiblity in metal or other polymers, and also in mechanical properties and paintability, and to a method for producing the same with good workability and production efficiency.
Further, the invention also relates to multilayer pellets excellent in adhesiveness to metal or other polymers and also in mechanical properties and paintability, and to a method for producing the same with good workability and production efficiency with less emission of odor.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2003-48991 discloses a multilayered pellets composed of a sheath including a component (A) and a core including a component (B) and/or a component (C), wherein
component (A): a crystalline polyolefin resin (A),
component (B): an olefin copolymer composed of two or more kinds of olefins selected from the group consisting of ethylene, propylene and a C4-20 α-olefin, the olefin copolymer having a total number of carbon atoms of the ethylene, propylene and C4-20 α-olefin of 6 or more and satisfying the inequity (1):[y/(x+y)]≧0.30  (1)wherein x is a content of the ethylene (mol %) and y is a content of the C4-20 α-olefin (mol %),component (C): (C-1) and/or (C-2)(C-1): a copolymer composed of a vinyl aromatic compound and a conjugated diene compound(C-2): a hydrogenated product of (C-1).
European Unexamined Patent Publication 1063070 A2 discloses a process for manufacturing multilayer pellets having a core-sheath structure with a molding material forming a sheath which covers around the outer circumference of another molding material forming a core, which process comprises:
(a): supplying the core material and the sheath material to a die equipment having a plurality of extrusion-forming parts arranged along a circumference,
(b): extruding a plurality of multilayer strands from the extrusion-forming parts by covering around the outer circumference of the core material concentrically with the sheath material, and
(c): cutting the extruded multilayer strands to manufacture multilayer pellets.
Japanese Unexamined Patent Publication No. 59-81121 discloses a method for producing a multilayer pellet, the method comprising melt-extruding a melt including at least one resin selected from the group consisting of olefin-vinyl alcohol copolymer, ion-crosslinked olefin copolymer and linear polyamide resin and a melt composed mainly of olefin-based resin to form a strand composed of a core of the former melt and a sheath of the latter melt, cooling the strand, and then cutting the strand to form pellets.