# US 10,500,777 B2 · Method and apparatus for forming an expandable foam pellet having a hard outer shell by underwater pelletizing, and expandable foam pellets formed thereby > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,500,777 B2 - Document ID: US10500777B2 - Status: Granted - Kind: B2 - Application number: 15/639,857 - Filed: 2017-06-30 - Published: 2018-01-04 - Granted: 2019-12-10 - Earliest claimed: 2016-07-01 - Assignees: Gala Industries, Inc. - Applicants: Gala Industries, Inc. - Inventors: Mark Anthony Lythgoe - Web page: https://patentgrep.com/patent/US10500777B2 ## CPC - B29C 48/0022: {combined with cutting} - B29B 9/065: {under-water, e.g. underwater pelletizers} - B29B 9/12: characterised by structure or composition - B29C 44/3461: {Making or treating expandable particles} - B29C 48/0012: {combined with shaping by internal pressure generated in the material, e.g. foaming} - B29C 48/04: Particle-shaped (making granules B29B9/00) - B29C 48/911: {Cooling} - B29K 2025/06: {PS, i.e. polystyrene} - B29K 2101/12: Thermoplastic materials - B29K 2105/0005: {containing compounding ingredients (releasing, lubricating or separating agents B29C33/56, fibers B29K2105/08, B29K2105/12; fillers B29K2105/16, recycled material B29K2105/26)} - B29K 2105/043: {Skinned foam} - B29K 2105/048: {Expandable particles, beads or granules} - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS ## Abstract A pre-expanded hard shell thermoplastic foam pellet is made by controlling the temperature of the melt exiting a die plate in an underfluid pelletizer, and by controlling the temperature and pressures of the cooling fluid as the pellet flows from the cutting chamber through the slurry line toward a centrifugal dryer. The process and apparatus used for controlling the above parameters is described in conjunction with making the pellets. The pellets thus formed may have a generally spherical shape, or they may have odd, irregular shapes with foam hemorrhages protruding therefrom, depending on the conditions during pre-expansion. ## Claims ### Claim 1 An extrusion process for producing pre-expanded foam pellets having a hard outer shell, the process comprising: metering a blowing agent into a polymer melt; forcing the polymer melt through an extrusion die and into a cutting chamber comprising a fluid inlet and a pellet slurry outlet and enclosing a cutter hub assembly comprising a plurality of cutter blades; cutting the extruded melt by rotating the plurality of cutter blades at a programmed rotation speed to produce one or more pellets; directing a flow of fluid in the fluid inlet, through the cutting chamber, and out the pellet slurry outlet to pull the one or more pellets away from the cutting chamber in a pellet slurry; and cooling the one or more pellets in the pellet slurry at a temperature and pressure effective to produce one or more foam pellets having a hard outer shell and a pre-expanded foam center. ### Claim 2 (depends on 1) The process of claim 1, wherein the blowing agent comprises a propane, butane, pentane, neopentane, isopentane, hexane, CO2, or combinations thereof. ### Claim 3 (depends on 1) The process of claim 1, wherein the blowing agent is added and mixed at a rate of between about 1 and about 7 percent weight. ### Claim 4 (depends on 1) The process of claim 1, wherein cutting the extruded melt further comprises varying the programmed rotation speed of the cutter blades. ### Claim 5 An extrusion process for producing pre-expanded foam pellets having a hard outer shell, the process comprising: feeding a polymer material into a material blending system to form a blended material; feeding the blended material into a throat of an extruder to form a polymer melt; metering a blowing agent into the melt; extruding the melt through an extrusion die and into a cutting chamber comprising a fluid inlet and a pellet slurry outlet and enclosing a cutter hub assembly comprising a plurality of cutter blades; cutting the extruded melt by rotating the plurality of cutter blades at a programmed rotation speed to produce one or more pellets; directing a flow of fluid in the fluid inlet, through the cutting chamber, and out the pellet slurry outlet to pull the one or more pellets away from the cutting chamber in a pellet slurry; and cooling the one or more pellets in the pellet slurry effective to produce one or more foam pellets having a hard outer shell and a pre-expanded foam center. ### Claim 6 (depends on 5) The process of claim 5, further comprising drying the one or more foam pellets. ### Claim 7 (depends on 6) The process of claim 6, further comprising further expanding the defluidized foam pellets via one or more of a heat and a steam treatment. ### Claim 8 (depends on 1) A pellet formed by the process of claim 1. ### Claim 9 (depends on 5) A pellet formed by the process of claim 5. ### Claim 10 (depends on 8) The pellet of claim 8, comprising a hard outer shell, and a pre-expanded foam center, wherein the hard outer shell encapsulates the pre-expanded foam center. ### Claim 11 (depends on 10) The pellet of claim 10, wherein the pre-expanded foam center is partially expanded such that it can be further expanded. ### Claim 12 (depends on 10) The pellet of claim 10, wherein the hard outer shell is generally spherical. ### Claim 13 (depends on 10) The pellet of claim 10, further comprising a hemorrhaged portion. ### Claim 14 (depends on 10) The pellet of claim 10, wherein the pre-expanded foam center has a hollow center region.