Foaming die and method of use

Patent metadata

Field	Value
Publication number	US-2017246776-A1
Application number	US-201515517049-A
Country	US
Kind code	A1
Filing date	Oct 20, 2015
Priority date	Oct 23, 2014
Publication date	Aug 31, 2017
Grant date	—

Abstract

Foam slabs and methods and apparatus, including foaming dies, for making and using foam slabs.

First claim

1 . A foaming die for extruding a molten foamable composition, comprising,
a working face comprising a plurality of laterally-aligned die orifices spaced along a lateral axis of the foaming die so as to define a die width and a die height,
wherein the die orifices each exhibit an elongated shape with a long axis that is oriented at least substantially orthogonal to the lateral axis of the foaming die and that is at least substantially aligned with a height axis of the foaming die,
wherein the die orifices each exhibit an orifice height to orifice width aspect ratio of at least about 4:1.

2 . (canceled)

3 . The foaming die of claim 1 wherein the die orifices exhibit an orifice height to orifice width aspect ratio of at least about 8:1.

4 - 5 . (canceled)

6 . The foaming die of claim 1 the die orifices are co-linearly spaced in a single row along the lateral axis of the foaming die and wherein all of the die orifices comprise at least essentially identical heights, which heights define the die height of the foaming die.

7 . The foaming die of claim 1 wherein the foaming die is provided at least in part by a plurality of shims that are layered together under pressure to form a shim stack, each shim exhibiting a major plane that is at least substantially parallel to a thickness axis of the foaming die, the shims combining to collectively define the die orifices of the foaming die and to define at least one die cavity that is fluidly connected to the die orifices.

8 . The foaming die of claim 1 wherein the foaming die is fluidly coupled to an extrusion apparatus that comprises at least one extruder and that is configured to continuously supply a molten foamable flowstream to at least one die cavity of the foaming die.

9 . The foaming die of claim 8 wherein the extrusion apparatus comprises first and second extruders fluidly connected to each other in tandem.

10 . The foaming die of claim 1 wherein the foaming die is configured to continuously emit molten foamable extrudate flowstreams comprising at least the molten foamable composition, into an undefined space that is not an interior of an injection molding cavity.

11 . The foaming die of claim 1 wherein the plurality of die orifices includes a first set of die orifices that are fluidly connected to a first die cavity that is configured to receive a first molten flowstream from an extruder, and a second set of die orifices that are fluidly connected to a second die cavity that is configured to receive a second molten flowstream from an extruder.

12 . The foaming die of claim 11 wherein the first die cavity is configured to receive the first molten flowstream from a first extruder, and wherein the second die cavity is configured to receive the second molten flowstream from a second extruder that is different from the first extruder.

13 . (canceled)

14 . The foaming die of claim 1 wherein at least some die orifices of the plurality of die orifices are in fluid communication with a die cavity that is configured to receive a multilayer molten flowstream from a multilayer feedblock, which multilayer feedblock is configured to receive molten flowstreams from at least two different extruders and to combine the molten flowstreams into the multilayer molten flowstream.

15 . The foaming die of claim 1 wherein the at least some of the die orifices each comprise a dogbone shape in which a width of the orifice in a location proximate a first terminal end of the orifice, and a width of the orifice in a location proximate a second terminal end of the orifice that is generally opposite the first terminal end of the orifice, are each larger than a width of the orifice in a section of the orifice that is centrally located along the long axis of the orifice.

16 . The foaming die of claim 1 wherein a center-to-center spacing of the laterally-aligned die orifices is at most about 15 mm.

17 . The foaming die of claim 1 wherein a center-to-center spacing of the laterally-aligned die orifices is at most about 10 mm.

18 . The foaming die of claim 1 wherein a center-to-center spacing of the laterally-aligned die orifices is at most about 5 mm.

19 . A method of making a unitary foam slab, comprising:
continuously emitting molten foamable extrudate flowstreams through at least selected die orifices of a plurality of die orifices of a foaming die,
wherein the die orifices are laterally-aligned and are spaced along a lateral axis of the foaming die so as to define a die width and a die height,
wherein the die orifices each exhibit an elongated shape with a long axis that is oriented at least substantially orthogonal to the lateral axis of the foaming die and each exhibit an orifice height to orifice width aspect ratio of at least about 4:1;
and, allowing the molten foamable extrudate flowstreams to foam and to coalesce and solidify as a unitary mass so as to form a unitary foam slab with a slab width and a slab thickness.

20 . The method of claim 19 , wherein the foaming die comprises at least one die cavity that continuously receives a molten foamable flowstream from an extrusion apparatus and that divides the molten foamable flowstream into molten foamable flowstreams that are continuously delivered to the die orifices to be emitted therefrom as the molten foamable extrudate flowstreams.

21 . The method of claim 19 , wherein:
the plurality of die orifices includes a first set of die orifices and a second set of die orifices, wherein at least selected die orifices of the second set of die orifices are each individually laterally sandwiched between pairs of die orifices of the first set of die orifices; and, wherein the method comprises continuously emitting first molten foamable extrudate flowstreams through the first set of die orifices, continuously emitting second molten extrudate flowstreams through the second set of die orifices, allowing the first molten foamable extrudate flowstreams to foam, allowing the first and second molten extrudate flowstreams to laterally coalesce with each other, and allowing the coalesced first and second molten extrudate flowstreams to solidify as a unitary mass to form a unitary composite foam slab.

22 . The method of claim 21 wherein the second molten extrudate flowstreams comprise a densified molten composition.

23 . The method of claim 21 , wherein the second molten extrudate flowstreams consist essentially of a molten non-foamable composition.

24 . The method of claim 19 , wherein at least some of the molten foamable extrudate flowstreams are vertically-stacked multilayer flowstreams, each multilayer flowstream comprising a primary molten layer that comprises a molten foamable composition and that provides at least a vertically central layer of the multilayer flowstream, and a secondary molten layer that provides an outer layer of the multilayer flowstream, and wherein the method includes allowing the primary molten layers and the secondary molten layers of the multilayer flowstreams to solidify as a unitary mass to form a unitary composite foam slab;
wherein the unitary composite foam slab comprises a major, foam layer that is derived from the primary molten layer, and a minor, surface layer that is derived from the secondary molten layer of the multilayer flowstream and that is a sheet-like layer that provides a major outer surface of the composite foam slab, and wherein the major, foam layer and the minor, surface layer each extend continuously across the

Assignees

• 3M Innovative Properties Co

Inventors

• Kalish Jeffrey P
• Jonza James M
• Koster Brian L
• Feisel Bryan C

Classifications

• B29C48/49

  using two or more extruders to feed one die or nozzle · CPC title

• B29C48/30

  Extrusion nozzles or dies (extrusion characterised by the shape or cross-section of the extruded article B29C48/03) · CPC title

• B29K2995/0063

  Density · CPC title

• B29K2995/0002

  insulating · CPC title

• B29K2105/04

  cellular or porous · CPC title